All Edge: Inside the New Workplace Networks, Spinuzzi
"Instead of projects coming to established teams, teams are increasingly converging around projects. These “all-edge adhocracies” are highly collaborative and mostly temporary, their edge coming from the ability to form links both inside and outside an organization. These nimble groups come together around a specific task, recruiting personnel, assigning roles, and establishing objectives. When the work is done they disband their members and take their skills to the next project.
"Spinuzzi offers for the first time a comprehensive framework for understanding how these new groups function and thrive. ..."
to:NB  books:noted  networks  economics  sociology 
4 days ago
Freedom Beyond Sovereignty: Reconstructing Liberal Individualism, Krause
"... we must move beyond the common assumption, prevalent in political theory and American public life, that individual agency is best conceived as a kind of personal sovereignty, or as self-determination or control over one’s actions.
"In Freedom Beyond Sovereignty, Sharon R. Krause shows that individual agency is best conceived as a non-sovereign experience because our ability to act and affect the world depends on how other people interpret and respond to what we do. The intersubjective character of agency makes it vulnerable to the effects of social inequality, but it is never in a strict sense socially determined...."
books:noted  to:NB  political_philosophy  philosophy_of_mind 
4 days ago
Koltchinskii : Empirical geometry of multivariate data: a deconvolution approach
"Let {Yj:j=1,…,n} be independent observations in ℝm,m≥1 with common distribution Q. Suppose that Yj=Xj+ξj,j=1,…,n, where {Xj,ξj,j=1,…,n} are independent, Xj,j=1,…,n have common distribution P and ξj,j=1,…,n have common distribution μ, so that Q=P∗μ. The problem is to recover hidden geometric structure of the support of P based on the independent observations Yj. Assuming that the distribution of the errors μ is known, deconvolution statistical estimates of the fractal dimension and the hierarchical cluster tree of the support that converge with exponential rates are suggested. Moreover, the exponential rates of convergence hold for adaptive versions of the estimates even in the case of normal noise ξj with unknown covariance. In the case of the dimension estimation, though, the exponential rate holds only when the set of all possible values of the dimension is finite (e.g., when the dimension is known to be integer). If this set is infinite, the optimal convergence rate of the estimator becomes very slow (typically, logarithmic), even when there is no noise in the observations."
in_NB  manifold_learning  factor_analysis  deconvolution  re:g_paper  statistics 
4 days ago
interfluidity » Surge!
I can see a case for raising prices around times of predictably high demand, _because_ that could increase supply, but raising prices in emergencies doesn't have the same logic to it...
economics  market_failures_in_everything  uber  have_read 
4 days ago
The ecology of dragons : Nature
Wasn't it Haldane who said that the two things separating men from angels were moral imperfection, and a body plan unable to accommodate six limbs?
have_read  evolutionary_biology  dragons  may.robert_m.  funny:geeky  to:blog 
4 days ago
Zoology: Here be dragons : Nature : Nature Publishing Group
"Emerging evidence indicates that dragons can no longer be dismissed as creatures of legend and fantasy, and that anthropogenic effects on the world's climate may inadvertently be paving the way for the resurgence of these beasts."

--- Figure 2 is a thing of beauty.
to:NB  have_read  dragons  ecology  climate_change  may.robert_m.  funny:geeky  to:blog 
4 days ago
The Growth of Incarceration in the United States: Exploring Causes and Consequences | The National Academies Press
"After decades of stability from the 1920s to the early 1970s, the rate of imprisonment in the United States more than quadrupled during the last four decades. The U.S. penal population of 2.2 million adults is by far the largest in the world. Just under one-quarter of the world's prisoners are held in American prisons. The U.S. rate of incarceration, with nearly 1 out of every 100 adults in prison or jail, is 5 to 10 times higher than the rates in Western Europe and other democracies. The U.S. prison population is largely drawn from the most disadvantaged part of the nation's population: mostly men under age 40, disproportionately minority, and poorly educated. Prisoners often carry additional deficits of drug and alcohol addictions, mental and physical illnesses, and lack of work preparation or experience. The growth of incarceration in the United States during four decades has prompted numerous critiques and a growing body of scientific knowledge about what prompted the rise and what its consequences have been for the people imprisoned, their families and communities, and for U.S. society."
to:NB  books:noted  crime  law  prison  public_policy  sociology  whats_gone_wrong_with_america 
4 days ago
Network Analysis and Political Science - Annual Review of Political Science, 14(1):245
"Political science is fascinated with networks. This fascination builds on networks' descriptive appeal, and descriptions of networks play a prominent role in recent forays into network analysis. For some time, quantitative research has included node-level measures of network characteristics in standard regression models, thereby incorporating network concepts into familiar models. This approach represents an early advance for the literature but may (a) ignore fundamental theoretical contributions that can be found in a more structurally oriented network perspective, (b) focus attention on superficial aspects of networks as they feed into empirical work, and (c) present the network perspective as a slight tweak to standard models that assume complete independence of all relevant actors. We argue that network analysis is more than a tweak to the status quo ante; rather, it offers a means of addressing one of the holy grails of the social sciences: effectively analyzing the interdependence and flows of influence among individuals, groups, and institutions."

--- OK as far as what it says, and Stovel certainly does excellent work, but I'm not sure what kind of reader both knows so little that this would be helpful, and so much that they can follow it....
to:NB  network_data_analysis  political_science  political_networks  have_skimmed 
5 days ago
Everyday Technology: Machines and the Making of India's Modernity, Arnold
"Everyday Technology is a pioneering account of how small machines and consumer goods that originated in Europe and North America became objects of everyday use in India in the late nineteenth and early twentieth centuries. Rather than investigate “big” technologies such as railways and irrigation projects, Arnold examines the assimilation and appropriation of bicycles, rice mills, sewing machines, and typewriters in India, and follows their impact on the ways in which people worked and traveled, the clothes they wore, and the kind of food they ate. "
to:NB  books:noted  history_of_technology  20th_century_history  19th_century_history  india  cultural_exchange 
15 days ago
Statistics Done Wrong | No Starch Press
"Scientific progress depends on good research, and good research needs good statistics. But statistical analysis is tricky to get right, even for the best and brightest of us. You'd be surprised how many scientists are doing it wrong.
"Statistics Done Wrong is a pithy, essential guide to statistical blunders in modern science that will show you how to keep your research blunder-free. You'll examine embarrassing errors and omissions in recent research, learn about the misconceptions and scientific politics that allow these mistakes to happen, and begin your quest to reform the way you and your peers do statistics.
"You'll find advice on:
"Asking the right question, designing the right experiment, choosing the right statistical analysis, and sticking to the plan
"How to think about p values, significance, insignificance, confidence intervals, and regression
"Choosing the right sample size and avoiding false positives
"Reporting your analysis and publishing your data and source code
"Procedures to follow, precautions to take, and analytical software that can help
"Scientists: Read this concise, powerful guide to help you produce statistically sound research.
"Statisticians: Give this book to everyone you know."

--- By one of our graduate students (!).
books:noted  statistics 
18 days ago
Morris, I.; Macedo, S.,: Foragers, Farmers, and Fossil Fuels: How Human Values Evolve. (eBook and Hardcover)
"Most people in the world today think democracy and gender equality are good, and that violence and wealth inequality are bad. But most people who lived during the 10,000 years before the nineteenth century thought just the opposite. Drawing on archaeology, anthropology, biology, and history, Ian Morris, author of the best-selling Why the West Rules—for Now, explains why. The result is a compelling new argument about the evolution of human values, one that has far-reaching implications for how we understand the past—and for what might happen next.
"Fundamental long-term changes in values, Morris argues, are driven by the most basic force of all: energy. Humans have found three main ways to get the energy they need—from foraging, farming, and fossil fuels. Each energy source sets strict limits on what kinds of societies can succeed, and each kind of society rewards specific values. In tiny forager bands, people who value equality but are ready to settle problems violently do better than those who aren’t; in large farming societies, people who value hierarchy and are less willing to use violence do best; and in huge fossil-fuel societies, the pendulum has swung back toward equality but even further away from violence.
"But if our fossil-fuel world favors democratic, open societies, the ongoing revolution in energy capture means that our most cherished values are very likely to turn out—at some point fairly soon—not to be useful any more.
"Originating as the Tanner Lectures delivered at Princeton University, the book includes challenging responses by novelist Margaret Atwood, philosopher Christine Korsgaard, classicist Richard Seaford, and historian of China Jonathan Spence."

--- I am going to be _so_ disappointed if this isn't full of quotes from Marx and Trotsky.
--- Also: Ernest Gellner wrote somewhere that it was fitting that the West defeated the fascists militarily, and the communists economically. In other words, the currently-dominant societies have neither in the past nor even in the present been at all averse to resolving problems violently, and in fact they've been much better at it than competitors. Perhaps Morris's argument is compatible with this, but it will take some fancy footwork.
to:NB  books:noted  history_of_morals  ethics  historical_materialism  philosophy 
18 days ago
Frontiers | Measurement invariance within and between individuals: a distinct problem in testing the equivalence of intra- and inter-individual model structures | Quantitative Psychology and Measurement
"We address the question of equivalence between modeling results obtained on intra-individual and inter-individual levels of psychometric analysis. Our focus is on the concept of measurement invariance and the role it may play in this context. We discuss this in general against the background of the latent variable paradigm, complemented by an operational demonstration in terms of a linear state-space model, i.e., a time series model with latent variables. Implemented in a multiple-occasion and multiple-subject setting, the model simultaneously accounts for intra-individual and inter-individual differences. We consider the conditions—in terms of invariance constraints—under which modeling results are generalizable (a) over time within subjects, (b) over subjects within occasions, and (c) over time and subjects simultaneously thus implying an equivalence-relationship between both dimensions. Since we distinguish the measurement model from the structural model governing relations between the latent variables of interest, we decompose the invariance constraints into those that involve structural parameters and those that involve measurement parameters and relate to measurement invariance. Within the resulting taxonomy of models, we show that, under the condition of measurement invariance over time and subjects, there exists a form of structural equivalence between levels of analysis that is distinct from full structural equivalence, i.e., ergodicity. We demonstrate how measurement invariance between and within subjects can be tested in the context of high-frequency repeated measures in personality research. Finally, we relate problems of measurement variance to problems of non-ergodicity as currently discussed and approached in the literature."
to:NB  psychometrics  social_measurement  psychology  ergodicity  borsboom.denny  re:g_paper 
18 days ago
Welcome to the CRCNS data sharing website — CRCNS.org
Sharing neural data; some of the data sets require an (anonymous) login.

--- See about using one of the movement data sets for a multivariate-analysis problem set (or exam?).
neuroscience  data_sets  to_teach:undergrad-ADA 
18 days ago
Altered resting state complexity in schizophrenia. - PubMed - NCBI
"The complexity of the human brain's activity and connectivity varies over temporal scales and is altered in disease states such as schizophrenia. Using a multi-level analysis of spontaneous low-frequency fMRI data stretching from the activity of individual brain regions to the coordinated connectivity pattern of the whole brain, we investigate the role of brain signal complexity in schizophrenia. Specifically, we quantitatively characterize the univariate wavelet entropy of regional activity, the bivariate pairwise functional connectivity between regions, and the multivariate network organization of connectivity patterns. Our results indicate that univariate measures of complexity are less sensitive to disease state than higher level bivariate and multivariate measures. While wavelet entropy is unaffected by disease state, the magnitude of pairwise functional connectivity is significantly decreased in schizophrenia and the variance is increased. Furthermore, by considering the network structure as a function of correlation strength, we find that network organization specifically of weak connections is strongly correlated with attention, memory, and negative symptom scores and displays potential as a clinical biomarker, providing up to 75% classification accuracy and 85% sensitivity. We also develop a general statistical framework for the testing of group differences in network properties, which is broadly applicable to studies where changes in network organization are crucial to the understanding of brain function."
to:NB  complexity_measures  functional_connectivity  schizophrenia  neuroscience  network_data_analysis  fmri  re:network_differences  bassett.danielle 
19 days ago
Network Methods to Characterize Brain Structure and Function
"Network science provides tools that can be used to understand the structure and function of the hu- man brain in novel ways using simple concepts and mathematical representations. Network neuroscience is a rapidly growing field with implications for systems neuroscience, cognitive neuroscience, and clinical medicine. In this chapter, we describe the methodology of network science as applied to neuroimaging data. We cover topics in constructing networks, probing network structure, generating network ‘diagnos- tics’, and experimental design. We discuss several current frontiers and the associated methodological challenges and considerations. We aim to provide a practical introduction to the field: we supplement the explanations and examples with pointers to resources for students or researchers interested in using these methods to address their own questions in empirical and theoretical neuroscience."
to:NB  to_read  neuroscience  network_data_analysis  networks  bassett.danielle 
19 days ago
Form’s Function | The Los Angeles Review of Books
Wonder what Franco "we need a sociology of literary form" Moretti makes of this, and vice versa...
book_reviews  books:noted  literary_criticism  aesthetics  form 
19 days ago
Yang , Tokdar : Minimax-optimal nonparametric regression in high dimensions
"Minimax L2 risks for high-dimensional nonparametric regression are derived under two sparsity assumptions: (1) the true regression surface is a sparse function that depends only on d=O(logn) important predictors among a list of p predictors, with logp=o(n); (2) the true regression surface depends on O(n) predictors but is an additive function where each additive component is sparse but may contain two or more interacting predictors and may have a smoothness level different from other components. For either modeling assumption, a practicable extension of the widely used Bayesian Gaussian process regression method is shown to adaptively attain the optimal minimax rate (up to logn terms) asymptotically as both n,p→∞ with logp=o(n)."

--- Err, isn't this just saying that if we assume the problem isn't really high-dimensional at all, it's not that hard? (And of course Gaussian process regression would work then; splines would work then!) I say this with all due respect for someone with whom I co-taught a class...
to:NB  regression  nonparametrics  minimax  statistics  high-dimensional_statistics 
20 days ago
Vogt , Dette : Detecting gradual changes in locally stationary processes
"In a wide range of applications, the stochastic properties of the observed time series change over time. The changes often occur gradually rather than abruptly: the properties are (approximately) constant for some time and then slowly start to change. In many cases, it is of interest to locate the time point where the properties start to vary. In contrast to the analysis of abrupt changes, methods for detecting smooth or gradual change points are less developed and often require strong parametric assumptions. In this paper, we develop a fully nonparametric method to estimate a smooth change point in a locally stationary framework. We set up a general procedure which allows us to deal with a wide variety of stochastic properties including the mean, (auto)covariances and higher moments. The theoretical part of the paper establishes the convergence rate of the new estimator. In addition, we examine its finite sample performance by means of a simulation study and illustrate the methodology by two applications to financial return data."
to:NB  to_read  non-stationarity  re:growing_ensemble_project  time_series  statistics 
20 days ago
[no title]
The first review seems the most compelling to me: the methodology sounds really dodgy (50% drop-out!), and, crucially, unreviewable.
education  academia  standardized_testing  via:?  have_read 
20 days ago
The Books of the Century, 1900-1999
It's fascinating to look back 80 or even 40 years and have no idea what most of these were. Also, there seems to have been a period from just after WWII to the early 1970s when the fiction list was much more receptive of translations than I'd have imagined possible (de Beauvoir!)
american_history  literary_history  via:? 
20 days ago
McCullagh : What is a statistical model?
"This paper addresses two closely related questions, "What is a statistical model?" and "What is a parameter?" The notions that a model must "make sense," and that a parameter must "have a well-defined meaning" are deeply ingrained in applied statistical work, reasonably well understood at an instinctive level, but absent from most formal theories of modelling and inference. In this paper, these concepts are defined in algebraic terms, using morphisms, functors and natural transformations. It is argued that inference on the basis of a model is not possible unless the model admits a natural extension that includes the domain for which inference is required. For example, prediction requires that the domain include all future units, subjects or time points. Although it is usually not made explicit, every sensible statistical model admits such an extension. Examples are given to show why such an extension is necessary and why a formal theory is required. In the definition of a subparameter, it is shown that certain parameter functions are natural and others are not. Inference is meaningful only for natural parameters. This distinction has important consequences for the construction of prior distributions and also helps to resolve a controversy concerning the Box-Cox model."

--- I'm not sure how to think about this; some of the ideas about requiring invariance (or equivariance) under various transformations make sense, but I don't know that they lead to anything positive, or need such arcane category-theoretic expression. We should however have cited this in our paper on projectibility & consistency under sampling. (I blame our referees for not making the connection.)
--- The discussion and rejoinder are worth reading. Kalman's contribution is very special.
have_read  in_NB  foundations_of_statistics  abstract_algebra  mccullagh.peter  statistics 
20 days ago
Vaart : The statistical work of Lucien Le Cam
"We give an overview and appraisal of the scientific work in theoretical statistics, and its impact, by Lucien Le Cam."

--- Evidently a man with no concern for making an impact, or even for making himself understood.
in_NB  have_read  statistics  le_cam.lucien  van_der_vaart.aad 
20 days ago
Inequality Is Bad for Growth of the Poor (But Not for That of the Rich)
"The paper assesses the impact of overall inequality, as well as inequality among the poor and among the rich, on the growth rates along various percentiles of the income distri- bution. The analysis uses micro-census data from U.S. states covering the period from 1960 to 2010. The paper finds evidence that high levels of inequality reduce the income growth of the poor and, if anything, help the growth of the rich. When inequality is deconstructed into bottom and top inequality, the analysis finds that it is mostly top inequality that is holding back growth at the bottom."

--- This is based on the Census public-use microdata, but evidently with a lot of massaging. Is the cleaned data available?
to:NB  economics  inequality  class_struggles_in_america  economic_growth  milanovic.branko  regression 
20 days ago
Origins of narcissism in children
"Narcissism levels have been increasing among Western youth, and contribute to societal problems such as aggression and violence. The origins of narcissism, however, are not well understood. Here, we report, to our knowledge, the first prospective longitudinal evidence on the origins of narcissism in children. We compared two perspectives: social learning theory (positing that narcissism is cultivated by parental overvaluation) and psychoanalytic theory (positing that narcissism is cultivated by lack of parental warmth). We timed the study in late childhood (ages 7–12), when individual differences in narcissism first emerge. In four 6-mo waves, 565 children and their parents reported child narcissism, child self-esteem, parental overvaluation, and parental warmth. Four-wave cross-lagged panel models were conducted. Results support social learning theory and contradict psychoanalytic theory: Narcissism was predicted by parental overvaluation, not by lack of parental warmth. Thus, children seem to acquire narcissism, in part, by internalizing parents’ inflated views of them (e.g., “I am superior to others” and “I am entitled to privileges”). Attesting to the specificity of this finding, self-esteem was predicted by parental warmth, not by parental overvaluation. These findings uncover early socialization experiences that cultivate narcissism, and may inform interventions to curtail narcissistic development at an early age."

--- Psychometrics based on self-reports, rather than any sort of second-party evaluation of actual behavior. Look for replication data?
to:NB  psychology  narcissism  graphical_models  time_series  statistics  personality  mental_testing 
21 days ago
Latent structure in random sequences drives neural learning toward a rational bias
"People generally fail to produce random sequences by overusing alternating patterns and avoiding repeating ones—the gambler’s fallacy bias. We can explain the neural basis of this bias in terms of a biologically motivated neural model that learns from errors in predicting what will happen next. Through mere exposure to random sequences over time, the model naturally develops a representation that is biased toward alternation, because of its sensitivity to some surprisingly rich statistical structure that emerges in these random sequences. Furthermore, the model directly produces the best-fitting bias-gain parameter for an existing Bayesian model, by which we obtain an accurate fit to the human data in random sequence production. These results show that our seemingly irrational, biased view of randomness can be understood instead as the perfectly reasonable response of an effective learning mechanism to subtle statistical structure embedded in random sequences."

--- I'll be very surprised to see how "overusing alternating patterns and avoiding repeating ones" can be made to fall out from any sort of Bayesian model that doesn't have it built in from the start. (In particular, the natural Bayesian model is that an unknown sequence is exchangeable, which would tend to imply more repeating patterns.)
to:NB  probability  cognitive_science  bayesianism 
21 days ago
Equality bias impairs collective decision-making across cultures
"We tend to think that everyone deserves an equal say in a debate. This seemingly innocuous assumption can be damaging when we make decisions together as part of a group. To make optimal decisions, group members should weight their differing opinions according to how competent they are relative to one another; whenever they differ in competence, an equal weighting is suboptimal. Here, we asked how people deal with individual differences in competence in the context of a collective perceptual decision-making task. We developed a metric for estimating how participants weight their partner’s opinion relative to their own and compared this weighting to an optimal benchmark. Replicated across three countries (Denmark, Iran, and China), we show that participants assigned nearly equal weights to each other’s opinions regardless of true differences in their competence—even when informed by explicit feedback about their competence gap or under monetary incentives to maximize collective accuracy. This equality bias, whereby people behave as if they are as good or as bad as their partner, is particularly costly for a group when a competence gap separates its members."

--- My immediate doubt is that if people are actually making a binding group decision, they'll have to carry it out after they reach their agreement, and _that_ is more likely when everyone feels they've had their say...
in_NB  decision-making  experimental_psychology  experimental_sociology  social_life_of_the_mind  collective_cognition  re:democratic_cognition  to_read 
21 days ago
Breakdown of the brain’s functional network modularity with awareness
"Neurobiological theories of awareness propose divergent accounts of the spatial extent of brain changes that support conscious perception. Whereas focal theories posit mostly local regional changes, global theories propose that awareness emerges from the propagation of neural signals across a broad extent of sensory and association cortex. Here we tested the scalar extent of brain changes associated with awareness using graph theoretical analysis applied to functional connectivity data acquired at ultra-high field while subjects performed a simple masked target detection task. We found that awareness of a visual target is associated with a degradation of the modularity of the brain’s functional networks brought about by an increase in intermodular functional connectivity. These results provide compelling evidence that awareness is associated with truly global changes in the brain’s functional connectivity."
to:NB  to_read  neuroscience  functional_connectivity  consciousness  community_discovery 
21 days ago
[1412.6572] Explaining and Harnessing Adversarial Examples
"Several machine learning models, including neural networks, consistently misclassify adversarial examples---inputs formed by applying small but intentionally worst-case perturbations to examples from the dataset, such that the perturbed input results in the model outputting an incorrect answer with high confidence. Early attempts at explaining this phenomenon focused on nonlinearity and overfitting. We argue instead that the primary cause of neural networks' vulnerability to adversarial perturbation is their linear nature. This explanation is supported by new quantitative results while giving the first explanation of the most intriguing fact about them: their generalization across architectures and training sets. Moreover, this view yields a simple and fast method of generating adversarial examples. Using this approach to provide examples for adversarial training, we reduce the test set error of a maxout network on the MNIST dataset."
to:NB  machine_learning  neural_networks  classifiers  to:blog 
25 days ago
A simple comprehensive model for the analysis of covariance structures: Some remarks on applications - McDonald - 2011 - British Journal of Mathematical and Statistical Psychology - Wiley Online Library
"To facilitate applications of a model for the analysis of covariance structures, some useful matrix identities and reparametorizations are given. Examples are given to illustrate the applicability of the model to longitudinal data, to treatments of ordered variables and to fitting the Rasch model for binary data."

--- Possibly useful for the intersection of confirmatory factor analysis and the rotation problem.
in_NB  factor_analysis  statistics  inference_to_latent_objects  re:g_paper 
26 days ago
The Rise of Writing | Cambridge University Press
"Millions of Americans routinely spend half their working day or more with their hands on keyboards and their minds on audiences - writing so much, in fact, that they have less time and appetite for reading. In this highly anticipated sequel to her award-winning Literacy in American Lives, Deborah Brandt moves beyond laments about the decline of reading to focus on the rise of writing. What happens when writing overtakes reading as the basis of people's daily literate experience? How does a societal shift toward writing affect the ways that people develop their literacy and understand its value? Drawing on recent interviews with people who write every day, Brandt explores this major turn in the development of mass literacy and examines the serious challenges it poses for America's educational mission and civic health."
in_NB  networked_life  writing  literacy  sociology  books:noted 
4 weeks ago
CRAN - Package markovchain
"Functions and S4 methods to create and manage discrete time Markov chains (DTMC) more easily. In addition functions to perform statistical (fitting and drawing random variates) and probabilistic (analysis of DTMC proprieties) analysis are provided."
markov_models  R  to_teach:statcomp 
4 weeks ago
New Evidence on the Impact of Financial Crises in Advanced Countries
"This paper examines the aftermath of financial crises in advanced countries in the four decades before the Great Recession. We construct a new series on financial distress in 24 OECD countries for the period 1967–2007. The series is based on assessments of the health of countries’ financial systems from a consistent, real-time narrative source; and it classifies financial distress on a relatively fine scale, rather than treating it as a 0-1 variable. We find that output declines following financial crises in modern advanced countries are highly variable, on average only moderate, and often temporary. One important driver of the variation in outcomes across crises appears to be the severity and persistence of the financial distress itself."
to:NB  finance  financial_crises  macroeconomics  economics  via:jbdelong 
4 weeks ago
The second laws of quantum thermodynamics
"The second law of thermodynamics places constraints on state transformations. It applies to systems composed of many particles, however, we are seeing that one can formulate laws of thermodynamics when only a small number of particles are interacting with a heat bath. Is there a second law of thermodynamics in this regime? Here, we find that for processes which are approximately cyclic, the second law for microscopic systems takes on a different form compared to the macroscopic scale, imposing not just one constraint on state transformations, but an entire family of constraints. We find a family of free energies which generalize the traditional one, and show that they can never increase. The ordinary second law relates to one of these, with the remainder imposing additional constraints on thermodynamic transitions. We find three regimes which determine which family of second laws govern state transitions, depending on how cyclic the process is. In one regime one can cause an apparent violation of the usual second law, through a process of embezzling work from a large system which remains arbitrarily close to its original state. These second laws are relevant for small systems, and also apply to individual macroscopic systems interacting via long-range interactions. By making precise the definition of thermal operations, the laws of thermodynamics are unified in this framework, with the first law defining the class of operations, the zeroth law emerging as an equivalence relation between thermal states, and the remaining laws being monotonicity of our generalized free energies."
to:NB  thermodynamics  quantum_mechanics  physics 
4 weeks ago
Evidence for recent, population-specific evolution of the human mutation rate
"As humans dispersed out of Africa they adapted to new environmental challenges, including changes in exposure to mutagenic solar radiation. Humans in temperate latitudes have acquired light skin that is relatively transparent to UV light, and some evidence suggests that their DNA damage response pathways have also experienced local adaptation. This raises the possibility that different populations have experienced different selective pressures affecting genome integrity. Here, I present evidence that the rate of a particular mutation type has recently increased in the European population, rising in frequency by 50% during the 40,000–80,000 y since Europeans began diverging from Asians. A comparison of SNPs private to Africa, Asia, and Europe in the 1000 Genomes data reveals that private European variation is enriched for the transition 5′-TCC-3′ → 5′-TTC-3′. Although it is not clear whether UV played a causal role in changing the European mutational spectrum, 5′-TCC-3′ → 5′-TTC-3′ is known to be the most common somatic mutation present in melanoma skin cancers, as well as the mutation most frequently induced in vitro by UV. Regardless of its causality, this change indicates that DNA replication fidelity has not remained stable even since the origin of modern humans and might have changed numerous times during our recent evolutionary history."
to:NB  historical_genetics  human_genetics  genetics  human_evolution 
4 weeks ago
Coding principles of the canonical cortical microcircuit in the avian brain
"Mammalian neocortex is characterized by a layered architecture and a common or “canonical” microcircuit governing information flow among layers. This microcircuit is thought to underlie the computations required for complex behavior. Despite the absence of a six-layered cortex, birds are capable of complex cognition and behavior. In addition, the avian auditory pallium is composed of adjacent information-processing regions with genetically identified neuron types and projections among regions comparable with those found in the neocortex. Here, we show that the avian auditory pallium exhibits the same information-processing principles that define the canonical cortical microcircuit, long thought to have evolved only in mammals. These results suggest that the canonical cortical microcircuit evolved in a common ancestor of mammals and birds and provide a physiological explanation for the evolution of neural processes that give rise to complex behavior in the absence of cortical lamination."

--- Ummm, isn't the "canonical microcircuit" reasonably hypothetical in mammals?
to:NB  to_read  neuroscience  neural_computation  birds  neural_coding_and_decoding 
4 weeks ago
Aronow , Green , Lee : Sharp bounds on the variance in randomized experiments
"We propose a consistent estimator of sharp bounds on the variance of the difference-in-means estimator in completely randomized experiments. Generalizing Robins [Stat. Med. 7 (1988) 773–785], our results resolve a well-known identification problem in causal inference posed by Neyman [Statist. Sci. 5 (1990) 465–472. Reprint of the original 1923 paper]. A practical implication of our results is that the upper bound estimator facilitates the asymptotically narrowest conservative Wald-type confidence intervals, with applications in randomized controlled and clinical trials."
to:NB  variance_estimation  experimental_design  causal_inference  statistics 
4 weeks ago
Székely , Rizzo : Partial distance correlation with methods for dissimilarities
"Distance covariance and distance correlation are scalar coefficients that characterize independence of random vectors in arbitrary dimension. Properties, extensions and applications of distance correlation have been discussed in the recent literature, but the problem of defining the partial distance correlation has remained an open question of considerable interest. The problem of partial distance correlation is more complex than partial correlation partly because the squared distance covariance is not an inner product in the usual linear space. For the definition of partial distance correlation, we introduce a new Hilbert space where the squared distance covariance is the inner product. We define the partial distance correlation statistics with the help of this Hilbert space, and develop and implement a test for zero partial distance correlation. Our intermediate results provide an unbiased estimator of squared distance covariance, and a neat solution to the problem of distance correlation for dissimilarities rather than distances."
to:NB  dependence_measures  statistics  hilbert_space  conditional_independence_tests 
4 weeks ago
Terror Cells - The Baffler
--- For full context, this needs to be read in conjunction with the chapter in Ehrenreich's _Brightsided_ about the intense propaganda she got, after her diagnosis of breast cancer, to keep up a positive attitude because that would boost her immune system and so help fight the cancer; with a heavy subtext of blaming the victim. Ugly stuff, based on bad biology.
--- That said, when I was trying to educate myself about signal transduction in the late 1990s, I don't recall any hesitation in my references when talking about cellular decision-making. (Maybe they were eccentric.)
cancer  molecular_biology  immunology  ehrenreich.barbara 
4 weeks ago
Purple Reign - The Baffler
Yahoo's continued survival does somewhat amaze me. (And yet AOL still exists and makes more than $9e7/yr.)
journalism  yahoo  corporate_stupidity  why_oh_why_cant_we_have_a_better_press_corps 
4 weeks ago
The spontaneous emergence of conventions: An experimental study of cultural evolution
"How do shared conventions emerge in complex decentralized social systems? This question engages fields as diverse as linguistics, sociology, and cognitive science. Previous empirical attempts to solve this puzzle all presuppose that formal or informal institutions, such as incentives for global agreement, coordinated leadership, or aggregated information about the population, are needed to facilitate a solution. Evolutionary theories of social conventions, by contrast, hypothesize that such institutions are not necessary in order for social conventions to form. However, empirical tests of this hypothesis have been hindered by the difficulties of evaluating the real-time creation of new collective behaviors in large decentralized populations. Here, we present experimental results—replicated at several scales—that demonstrate the spontaneous creation of universally adopted social conventions and show how simple changes in a population’s network structure can direct the dynamics of norm formation, driving human populations with no ambition for large scale coordination to rapidly evolve shared social conventions."
to:NB  to_read  centola.damon  self-organization  institutions  social_networks  re:do-institutions-evolve 
4 weeks ago
Intelligence Emerging | The MIT Press
"Emergence—the formation of global patterns from solely local interactions—is a frequent and fascinating theme in the scientific literature both popular and academic. In this book, Keith Downing undertakes a systematic investigation of the widespread (if often vague) claim that intelligence is an emergent phenomenon. Downing focuses on neural networks, both natural and artificial, and how their adaptability in three time frames—phylogenetic (evolutionary), ontogenetic (developmental), and epigenetic (lifetime learning)—underlie the emergence of cognition. Integrating the perspectives of evolutionary biology, neuroscience, and artificial intelligence, Downing provides a series of concrete examples of neurocognitive emergence. Doing so, he offers a new motivation for the expanded use of bio-inspired concepts in artificial intelligence (AI), in the subfield known as Bio-AI.
"One of Downing’s central claims is that two key concepts from traditional AI, search and representation, are key to understanding emergent intelligence as well. He first offers introductory chapters on five core concepts: emergent phenomena, formal search processes, representational issues in Bio-AI, artificial neural networks (ANNs), and evolutionary algorithms (EAs). Intermediate chapters delve deeper into search, representation, and emergence in ANNs, EAs, and evolving brains. Finally, advanced chapters on evolving artificial neural networks and information-theoretic approaches to assessing emergence in neural systems synthesize earlier topics to provide some perspective, predictions, and pointers for the future of Bio-AI."
to:NB  books:noted  artificial_intelligence  neural_networks  genetic_algorithms  cognitive_science  emergence 
4 weeks ago
Why Democracy Is Oppositional — John Medearis | Harvard University Press
"Is infrequent voting the most we can expect from a free citizenry? Would democracy be more robust if our political discourse were more deliberative? John Medearis’s trenchant and trend-bucking work of political philosophy argues that democracies face significant challenges that go beyond civic lethargy and unreasonable debate. Democracy is inherently a fragile state of affairs, he reminds us. Revisiting fundamental questions about the system in theory and practice, Why Democracy Is Oppositional helps us see why preserving democracy has always been—and will always be—a struggle.
"As citizens of democracies seek political control over their destinies, they confront forces that threaten to dominate their lives. These forces may take the form of runaway financial markets, powerful special interests, expanding militaries, or dysfunctional legislatures. But citizens of democracies help create the very institutions that overwhelm them. Hostile threats do not generally come from the outside but are the product of citizens’ own collective activities. Medearis contends that democratic action perpetually arises to reclaim egalitarian control over social forces and institutions that have become alienated from large numbers of citizens. Democracy is therefore necessarily oppositional. Concerted, contentious political activities of all kinds are fundamental to it, while consensus and easy compromise are rarities."
in_NB  books:noted  political_philosophy  democracy  re:democratic_cognition 
5 weeks ago
Photography and the Art of Chance — Robin Kelsey | Harvard University Press
"Photography has a unique relationship to chance. Anyone who has wielded a camera has taken a picture ruined by an ill-timed blink or enhanced by an unexpected gesture or expression. Although this proneness to chance may amuse the casual photographer, Robin Kelsey points out that historically it has been a mixed blessing for those seeking to make photographic art. On the one hand, it has weakened the bond between maker and picture, calling into question what a photograph can be said to say. On the other hand, it has given photography an extraordinary capacity to represent the unpredictable dynamism of modern life. By delving into these matters, Photography and the Art of Chance transforms our understanding of photography and the work of some of its most brilliant practitioners.
"The effort to make photographic art has involved a call and response across generations. From the introduction of photography in 1839 to the end of the analog era, practitioners such as William Henry Fox Talbot, Julia Margaret Cameron, Alfred Stieglitz, Frederick Sommer, and John Baldessari built upon and critiqued one another’s work in their struggle to reconcile aesthetic aspiration and mechanical process. The root problem was the technology’s indifference, its insistence on giving a bucket the same attention as a bishop and capturing whatever wandered before the lens. Could such an automatic mechanism accommodate imagination? Could it make art? Photography and the Art of Chance reveals how daring innovators expanded the aesthetic limits of photography to create art for a modern world."
to:NB  books:noted  photography  art_history 
5 weeks ago
Imperialism and the Origins of Mexican Culture — Colin M. MacLachlan | Harvard University Press
"With an empire stretching across central Mexico, unmatched in military and cultural might, the Aztecs seemed poised on the brink of a golden age in the early sixteenth century. But the arrival of the Spanish changed everything. Imperialism and the Origins of Mexican Culture chronicles this violent clash of two empires and shows how modern Mestizo culture evolved over the centuries as a synthesis of Old and New World civilizations.
"Colin MacLachlan begins by tracing Spain and Mesoamerica’s parallel trajectories from tribal enclaves to complex feudal societies. When the Spanish laid siege to Tenochtitlán and destroyed it in 1521, the Aztecs could only interpret this catastrophe in cosmic terms. With their gods discredited and their population ravaged by epidemics, they succumbed quickly to Spanish control—which meant submitting to Christianity. Spain had just emerged from its centuries-long struggle against the Moors, and zealous Christianity was central to its imperial vision. But Spain’s conquistadores far outnumbered its missionaries, and the Church’s decision to exclude Indian converts from priesthood proved shortsighted. Native religious practices persisted, and a richly blended culture—part Indian, part Christian—began to emerge.
"The religious void left in the wake of Spain’s conquests had enduring consequences. MacLachlan’s careful analysis explains why Mexico is culturally a Mestizo country while ethnically Indian, and why modern Mexicans remain largely orphaned from their indigenous heritage—the adopted children of European history."
to:NB  books:noted  imperialism  early_modern_european_history  native_american_history  cultural_exchange 
5 weeks ago
[1503.02780] Replication, Communication, and the Population Dynamics of Scientific Discovery
"Many published research results are false (Ioannidis 2005), and controversy continues over the roles of replication and publication policy in improving the reliability of research. We develop a mathematical model of scientific discovery in the context of replication, publication bias, and variation in research quality. This model provides a formal framework for reasoning about the normative structure of science. We show that replication may serve as a ratchet that gradually separates true hypotheses from false, but the same factors that make initial findings unreliable also make replications unreliable. The most important factors in improving the reliability of research are the rate of false positives and the base rate of true hypotheses, and we offer suggestions for accomplishing these goals. Our results also clarify recent debates on the communication of replications. Surprisingly, publication bias is not always an obstacle, but instead may have positive impacts---suppression of negative novel findings is often beneficial. We also find that communication of negative replications serves the scientific community even when replicated studies have diminished power. Our model is only a start, but it speaks directly to ongoing debates about the design and conduct of science."

--- What happens in this model if they set the base rate of true hypotheses to 0?
to:NB  to_read  sociology_of_science  re:neutral_model_of_inquiry  science_as_a_social_process  sociology  re:democratic_cognition 
5 weeks ago
Naghshvar , Javidi : Active sequential hypothesis testing
"Consider a decision maker who is responsible to dynamically collect observations so as to enhance his information about an underlying phenomena of interest in a speedy manner while accounting for the penalty of wrong declaration. Due to the sequential nature of the problem, the decision maker relies on his current information state to adaptively select the most “informative” sensing action among the available ones.
"In this paper, using results in dynamic programming, lower bounds for the optimal total cost are established. The lower bounds characterize the fundamental limits on the maximum achievable information acquisition rate and the optimal reliability. Moreover, upper bounds are obtained via an analysis of two heuristic policies for dynamic selection of actions. It is shown that the first proposed heuristic achieves asymptotic optimality, where the notion of asymptotic optimality, due to Chernoff, implies that the relative difference between the total cost achieved by the proposed policy and the optimal total cost approaches zero as the penalty of wrong declaration (hence the number of collected samples) increases. The second heuristic is shown to achieve asymptotic optimality only in a limited setting such as the problem of a noisy dynamic search. However, by considering the dependency on the number of hypotheses, under a technical condition, this second heuristic is shown to achieve a nonzero information acquisition rate, establishing a lower bound for the maximum achievable rate and error exponent. In the case of a noisy dynamic search with size-independent noise, the obtained nonzero rate and error exponent are shown to be maximum."
to:NB  hypothesis_testing  learning_theory  statistics  javidi.tara 
5 weeks ago
Power Density | The MIT Press
"In this book, Vaclav Smil argues that power density is a key determinant of the nature and dynamics of energy systems. Any understanding of complex energy systems must rely on quantitative measures of many fundamental variables. Power density—the rate of energy flux per unit of area—is an important but largely overlooked measure. Smil provides the first systematic, quantitative appraisal of power density, offering detailed reviews of the power densities of renewable energy flows, fossil fuels, thermal electricity generation, and all common energy uses.
"Smil shows that careful quantification, critical appraisals, and revealing comparisons of power densities make possible a deeper understanding of the ways we harness, convert, and use energies. Conscientious assessment of power densities, he argues, proves particularly revealing when contrasting the fossil fuel–based energy system with renewable energy conversions.
"Smil explains that modern civilization has evolved as a direct expression of the high power densities of fossil fuel extraction. He argues that our inevitable (and desirable) move to new energy arrangements involving conversions of lower-density renewable energy sources will require our society—currently dominated by megacities and concentrated industrial production—to undergo a profound spatial restructuring of its energy system."

--- The last bit seems like a non sequitur; with electrical power transmission, power/area doesn't depend on the ultimate free energy source, though the latter might have to be more spread out. But Smil is an extremely smart guy, so he's probably thinking of something that's just not occurring to me at the moment.
Also, I feel like I've encountered this "energy density" before as a complexity measure, but just where is eluding me.
to:NB  books:noted  energy  physics  smil.vaclav 
5 weeks ago
The Least Likely Man: Marshall Nirenberg and the Discovery of the Genetic Code | The MIT Press
"The genetic code is the Rosetta Stone by which we interpret the 3.3 billion letters of human DNA, the alphabet of life, and the discovery of the code has had an immeasurable impact on science and society. In 1968, Marshall Nirenberg, an unassuming government scientist working at the National Institutes of Health, shared the Nobel Prize for cracking the genetic code. He was the least likely man to make such an earth-shaking discovery, and yet he had gotten there before such members of the scientific elite as James Watson and Francis Crick. How did Nirenberg do it, and why is he so little known? In The Least Likely Man, Franklin Portugal tells the fascinating life story of a famous scientist that most of us have never heard of.
"Nirenberg did not have a particularly brilliant undergraduate or graduate career. After being hired as a researcher at the NIH, he quietly explored how cells make proteins. Meanwhile, Watson, Crick, and eighteen other leading scientists had formed the “RNA Tie Club” (named after the distinctive ties they wore, each decorated with one of twenty amino acid designs), intending to claim credit for the discovery of the genetic code before they had even worked out the details. They were surprised, and displeased, when Nirenberg announced his preliminary findings of a genetic code at an international meeting in Moscow in 1961.
"Drawing on Nirenberg’s “lab diaries,” Portugal offers an engaging and accessible account of Nirenberg’s experimental approach, describes counterclaims by Crick, Watson, and Sidney Brenner, and traces Nirenberg’s later switch to an entirely new, even more challenging field. Having won the Nobel for his work on the genetic code, Nirenberg moved on to the next frontier of biological research: how the brain works."
to:NB  books:noted  molecular_biology  genetics  history_of_science 
5 weeks ago
Liberalism in Practice | The MIT Press
"At the core of liberal theory is the idea—found in thinkers from Hobbes to Rawls—that the consent of the governed is key to establishing political legitimacy. But in a diverse liberal polity like the United States, disagreement runs deep, and a segment of the population will simply regard the regime as illegitimate. In Liberalism in Practice, Olivia Newman argues that if citizens were to approach politics in the spirit of public reason, couching arguments in terms that others can reasonably accept, institutional and political legitimacy would be enhanced.
"Liberal theory has relied on the assumption of a unified self, that individuals are unified around a single set of goals, beliefs, attitudes, and aptitudes. Drawing on empirical findings in psychology, Newman argues instead that we are complex creatures whose dispositions and traits develop differently in different domains; we hold different moral commitments in different parts of our lives. She argues further that this domain differentiation allows us to be good liberal citizens in the public domain while remaining true to private commitments and beliefs in other domains. Newman proposes that educational and institutional arrangements can use this capacity for differentiation to teach public reason without overwhelming conflicting commitments. The psychology and pedagogy of public reason proposed by Newman move beyond John Rawls’s strictly political liberalism toward what Newman terms practical liberalism. Although we cannot resolve every philosophical problem bedeviling theories of liberalism, we can enjoy the myriad benefits of liberalism in practice."
in_NB  liberalism  social_life_of_the_mind  books:noted 
5 weeks ago
The Hungry Mind — Susan Engel | Harvard University Press
"Despite American education’s recent mania for standardized tests, testing misses what really matters about learning: the desire to learn in the first place. Curiosity is vital, but it remains a surprisingly understudied characteristic. The Hungry Mind is a deeply researched, highly readable exploration of what curiosity is, how it can be measured, how it develops in childhood, and how it can be fostered in school.
"Children naturally possess an active interest in knowing more about the world around them. But what begins as a robust trait becomes more fragile over time, and is shaped by experiences with parents, teachers, peers, and the learning environment. Susan Engel highlights the centrality of language and question-asking as crucial tools for expressing curiosity. She also uncovers overlooked forms of curiosity, such as gossip—an important way children satisfy their interest in other people. Although curiosity leads to knowledge, it can stir up trouble, and schools too often have an incentive to squelch it in favor of compliance and discipline.
"Balanced against the interventions of hands-on instructors and hovering parents, Engel stresses the importance of time spent alone, which gives children a chance to tinker, collect, read about the things that interest them, and explore their own thoughts. In addition to providing a theoretical framework for the psychology of curiosity, The Hungry Mind offers educators practical ways to put curiosity at the center of the classroom and encourage children’s natural eagerness to learn."
to:NB  books:noted  curiosity  education  psychology  mental_testing 
5 weeks ago
Living Originalism — Jack M. Balkin | Harvard University Press
"Originalism and living constitutionalism, so often understood to be diametrically opposing views of our nation’s founding document, are not in conflict—they are compatible. So argues Jack Balkin, one of the leading constitutional scholars of our time, in this long-awaited book. Step by step, Balkin gracefully outlines a constitutional theory that demonstrates why modern conceptions of civil rights and civil liberties, and the modern state’s protection of national security, health, safety, and the environment, are fully consistent with the Constitution’s original meaning. And he shows how both liberals and conservatives, working through political parties and social movements, play important roles in the ongoing project of constitutional construction.
"By making firm rules but also deliberately incorporating flexible standards and abstract principles, the Constitution’s authors constructed a framework for politics on which later generations could build. Americans have taken up this task, producing institutions and doctrines that flesh out the Constitution’s text and principles. Balkin’s analysis offers a way past the angry polemics of our era, a deepened understanding of the Constitution that is at once originalist and living constitutionalist, and a vision that allows all Americans to reclaim the Constitution as their own."

--- Isn't this just one of the basic paradoxes of original intent? ("We wanted _you_ to figure that part out.") But Balkin is a good writer, despite being a law professor and having consumed well over the LD50 of Yale lit-crit.
to:NB  books:noted  law  us_politics  balkin.jack_m. 
5 weeks ago
Underdogs — Aaron B. O'Connell | Harvard University Press
"The Marine Corps has always considered itself a breed apart. Since 1775, America’s smallest armed service has been suspicious of outsiders and deeply loyal to its traditions. Marines believe in nothing more strongly than the Corps’ uniqueness and superiority, and this undying faith in its own exceptionalism is what has made the Marines one of the sharpest, swiftest tools of American military power. Along with unapologetic self-promotion, a strong sense of identity has enabled the Corps to exert a powerful influence on American politics and culture.
"Aaron O’Connell focuses on the period from World War II to Vietnam, when the Marine Corps transformed itself from America’s least respected to its most elite armed force. He describes how the distinctive Marine culture played a role in this ascendancy. Venerating sacrifice and suffering, privileging the collective over the individual, Corps culture was saturated with romantic and religious overtones that had enormous marketing potential in a postwar America energized by new global responsibilities. Capitalizing on this, the Marines curried the favor of the nation’s best reporters, befriended publishers, courted Hollywood and Congress, and built a public relations infrastructure that would eventually brand it as the most prestigious military service in America.
"But the Corps’ triumphs did not come without costs, and O’Connell writes of those, too, including a culture of violence that sometimes spread beyond the battlefield. And as he considers how the Corps’ interventions in American politics have ushered in a more militarized approach to national security, O’Connell questions its sustainability."

--- Cf. Rick's _Making the Corps_?
to:NB  books:noted  american_history  us_military 
5 weeks ago
Cross-language differences in the brain network subserving intelligible speech
"How is language processed in the brain by native speakers of different languages? Is there one brain system for all languages or are different languages subserved by different brain systems? The first view emphasizes commonality, whereas the second emphasizes specificity. We investigated the cortical dynamics involved in processing two very diverse languages: a tonal language (Chinese) and a nontonal language (English). We used functional MRI and dynamic causal modeling analysis to compute and compare brain network models exhaustively with all possible connections among nodes of language regions in temporal and frontal cortex and found that the information flow from the posterior to anterior portions of the temporal cortex was commonly shared by Chinese and English speakers during speech comprehension, whereas the inferior frontal gyrus received neural signals from the left posterior portion of the temporal cortex in English speakers and from the bilateral anterior portion of the temporal cortex in Chinese speakers. Our results revealed that, although speech processing is largely carried out in the common left hemisphere classical language areas (Broca’s and Wernicke’s areas) and anterior temporal cortex, speech comprehension across different language groups depends on how these brain regions interact with each other. Moreover, the right anterior temporal cortex, which is crucial for tone processing, is equally important as its left homolog, the left anterior temporal cortex, in modulating the cortical dynamics in tone language comprehension. The current study pinpoints the importance of the bilateral anterior temporal cortex in language comprehension that is downplayed or even ignored by popular contemporary models of speech comprehension."

--- I think this would be a very tricky study to do properly. You'd ideally want to compare native-Chinese processing Chinese to native-English speakers processing English, but somehow ensure that the subjects were equally likely to be native speakers of either language. (Kids with exactly one ex-pat parent in Hong Kong?)
to:NB  fmri  graphical_models  causal_inference  neuroscience  linguistics 
5 weeks ago
Interplay of approximate planning strategies
"Humans routinely formulate plans in domains so complex that even the most powerful computers are taxed. To do so, they seem to avail themselves of many strategies and heuristics that efficiently simplify, approximate, and hierarchically decompose hard tasks into simpler subtasks. Theoretical and cognitive research has revealed several such strategies; however, little is known about their establishment, interaction, and efficiency. Here, we use model-based behavioral analysis to provide a detailed examination of the performance of human subjects in a moderately deep planning task. We find that subjects exploit the structure of the domain to establish subgoals in a way that achieves a nearly maximal reduction in the cost of computing values of choices, but then combine partial searches with greedy local steps to solve subtasks, and maladaptively prune the decision trees of subtasks in a reflexive manner upon encountering salient losses. Subjects come idiosyncratically to favor particular sequences of actions to achieve subgoals, creating novel complex actions or “options.”"
to:NB  cognitive_science  computational_complexity  planning  decision-making  heuristics  to_read  psychology  experimental_psychology  bounded_rationality 
5 weeks ago
On convex relaxation of graph isomorphism
"We consider the problem of exact and inexact matching of weighted undirected graphs, in which a bijective correspondence is sought to minimize a quadratic weight disagreement. This computationally challenging problem is often relaxed as a convex quadratic program, in which the space of permutations is replaced by the space of doubly stochastic matrices. However, the applicability of such a relaxation is poorly understood. We define a broad class of friendly graphs characterized by an easily verifiable spectral property. We prove that for friendly graphs, the convex relaxation is guaranteed to find the exact isomorphism or certify its inexistence. This result is further extended to approximately isomorphic graphs, for which we develop an explicit bound on the amount of weight disagreement under which the relaxation is guaranteed to find the globally optimal approximate isomorphism. We also show that in many cases, the graph matching problem can be further harmlessly relaxed to a convex quadratic program with only n separable linear equality constraints, which is substantially more efficient than the standard relaxation involving 2n equality and n2 inequality constraints. Finally, we show that our results are still valid for unfriendly graphs if additional information in the form of seeds or attributes is allowed, with the latter satisfying an easy to verify spectral characteristic."
to:NB  graph_theory  computational_complexity  optimization  convexity  network_data_analysis  re:network_differences 
5 weeks ago
Defining the Anthropocene : Nature : Nature Publishing Group
"Time is divided by geologists according to marked shifts in Earth’s state. Recent global environmental changes suggest that Earth may have entered a new human-dominated geological epoch, the Anthropocene. Here we review the historical genesis of the idea and assess anthropogenic signatures in the geological record against the formal requirements for the recognition of a new epoch. The evidence suggests that of the various proposed dates two do appear to conform to the criteria to mark the beginning of the Anthropocene: 1610 and 1964. The formal establishment of an Anthropocene Epoch would mark a fundamental change in the relationship between humans and the Earth system."

--- My never-to-be-written piece on Galileo was going to be titled "1610: The Year We Made Contact", so naturally I approve of the former date.
to:NB  geology  anthropocene  the_earth_as_transformed_by_human_action  we_are_as_gods_and_might_as_well_get_good_at_it 
5 weeks ago
Mechanosensory interactions drive collective behaviour in Drosophila : Nature : Nature Publishing Group
"Collective behaviour enhances environmental sensing and decision-making in groups of animals1, 2. Experimental and theoretical investigations of schooling fish, flocking birds and human crowds have demonstrated that simple interactions between individuals can explain emergent group dynamics3, 4. These findings indicate the existence of neural circuits that support distributed behaviours, but the molecular and cellular identities of relevant sensory pathways are unknown. Here we show that Drosophila melanogaster exhibits collective responses to an aversive odour: individual flies weakly avoid the stimulus, but groups show enhanced escape reactions. Using high-resolution behavioural tracking, computational simulations, genetic perturbations, neural silencing and optogenetic activation we demonstrate that this collective odour avoidance arises from cascades of appendage touch interactions between pairs of flies. Inter-fly touch sensing and collective behaviour require the activity of distal leg mechanosensory sensilla neurons and the mechanosensory channel NOMPC5, 6. Remarkably, through these inter-fly encounters, wild-type flies can elicit avoidance behaviour in mutant animals that cannot sense the odour—a basic form of communication. Our data highlight the unexpected importance of social context in the sensory responses of a solitary species and open the door to a neural-circuit-level understanding of collective behaviour in animal groups."

--- Metaphorical application of the finding that "wild-type flies can elicit avoidance behaviour in mutant animals that cannot sense the odour" is left as an exercise.
to:NB  experimental_biology  experimental_psychology  social_life_of_the_mind  collective_cognition  drosophila  neuroscience 
5 weeks ago
Ongoing hydrothermal activities within Enceladus : Nature : Nature Publishing Group
"Detection of sodium-salt-rich ice grains emitted from the plume of the Saturnian moon Enceladus suggests that the grains formed as frozen droplets from a liquid water reservoir that is, or has been, in contact with rock1, 2. Gravitational field measurements suggest a regional south polar subsurface ocean of about 10 kilometres thickness located beneath an ice crust 30 to 40 kilometres thick3. These findings imply rock–water interactions in regions surrounding the core of Enceladus. The resulting chemical ‘footprints’ are expected to be preserved in the liquid and subsequently transported upwards to the near-surface plume sources, where they eventually would be ejected and could be measured by a spacecraft4. Here we report an analysis of silicon-rich, nanometre-sized dust particles5, 6, 7, 8 (so-called stream particles) that stand out from the water-ice-dominated objects characteristic of Saturn. We interpret these grains as nanometre-sized SiO2 (silica) particles, initially embedded in icy grains emitted from Enceladus’ subsurface waters and released by sputter erosion in Saturn’s E ring. The composition and the limited size range (2 to 8 nanometres in radius) of stream particles indicate ongoing high-temperature (>90 °C) hydrothermal reactions associated with global-scale geothermal activity that quickly transports hydrothermal products from the ocean floor at a depth of at least 40 kilometres up to the plume of Enceladus."
to_read  astronomy  enceladus  saturn  physics 
5 weeks ago
Large-scale discovery of novel genetic causes of developmental disorders : Nature : Nature Publishing Group
"Despite three decades of successful, predominantly phenotype-driven discovery of the genetic causes of monogenic disorders1, up to half of children with severe developmental disorders of probable genetic origin remain without a genetic diagnosis. Particularly challenging are those disorders rare enough to have eluded recognition as a discrete clinical entity, those with highly variable clinical manifestations, and those that are difficult to distinguish from other, very similar, disorders. Here we demonstrate the power of using an unbiased genotype-driven approach2 to identify subsets of patients with similar disorders. By studying 1,133 children with severe, undiagnosed developmental disorders, and their parents, using a combination of exome sequencing3, 4, 5, 6, 7, 8, 9, 10, 11 and array-based detection of chromosomal rearrangements, we discovered 12 novel genes associated with developmental disorders. These newly implicated genes increase by 10% (from 28% to 31%) the proportion of children that could be diagnosed. Clustering of missense mutations in six of these newly implicated genes suggests that normal development is being perturbed by an activating or dominant-negative mechanism. Our findings demonstrate the value of adopting a comprehensive strategy, both genome-wide and nationwide, to elucidate the underlying causes of rare genetic disorders."
to:NB  genomics  human_genetics  neuroscience  medicine  genetics 
5 weeks ago
Evaluation of Probabilistic Forecasts: Proper Scoring Rules and Moments
"The paper provides an overview of probabilistic forecasting and discusses a the- oretical framework for evaluation of probabilistic forecasts which is based on proper scoring rules and moments. An artificial example of predicting second-order autore- gression and an example of predicting the RTSI stock index are used as illustrations."
to:NB  to_read  prediction  statistics  calibration 
5 weeks ago
The U.S. job skills mismatch and up-skilling - Washington Center for Equitable Growth
Why would employers raise the skills they require, as opposed to just offering lower wages? Two hypothesis spring to mind:
1. Caution on the part of those doing the actual hiring decisions. If a new hire doesn't work out, "How was I to know someone with their credentials wouldn't work out?" is a lot more defensible than "Well, they were willing to do the job for $5/hr less than anyone else with the minimum qualifications".
2. Bossing around those with more formal credentials and qualifications is itself a good for employers.
economics  financial_crisis_of_2007--  class_struggles_in_america 
5 weeks ago
Empire of Chance — Anders Engberg-Pedersen | Harvard University Press
"Napoleon’s campaigns were the most complex military undertakings in history before the nineteenth century. But the defining battles of Austerlitz, Borodino, and Waterloo changed more than the nature of warfare. Concepts of chance, contingency, and probability became permanent fixtures in the West’s understanding of how the world works. Empire of Chance examines anew the place of war in the history of Western thought, showing how the Napoleonic Wars inspired a new discourse on knowledge.
"Soldiers returning from the battlefields were forced to reconsider basic questions about what it is possible to know and how decisions are made in a fog of imperfect knowledge. Artists and intellectuals came to see war as embodying modernity itself. The theory of war espoused in Carl von Clausewitz’s classic treatise responded to contemporary developments in mathematics and philosophy, and the tools for solving military problems—maps, games, and simulations—became models for how to manage chance. On the other hand, the realist novels of Balzac, Stendhal, and Tolstoy questioned whether chance and contingency could ever be described or controlled."
to:NB  history_of_ideas  19th_century_history  war  probability  to_be_shot_after_a_fair_trial 
5 weeks ago
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