A single continuous function as a model for fast rise exponential decay gamma-ray bursts

A quantitative analysis was performed on a sample of Fast-Rise Exponential-Decay gamma-ray bursts using a continuous fitting function. The data were obtained from the Large Area detector catalogue of the Burst and Transient Source Experiment, which flew from 1991-2000 onboard the Compton Gamma-Ray Observatory. The purpose here is to tabulate from the fits quantities associated with gamma-ray bursts, emphasising peak intensity, duration, and characteristic rates of rising and falling. V/Vmax and duration analyses show that the sample of bursts is representative of the larger population of gamma-ray bursts. A modified asymmetric double sigmoidal was found to fit the background subtracted peaks for the majority of bursts. From the regressions the amplitude, duration and rising and falling characteristic times are defined for each burst, as well as a value describing the asymmetry of the peak. These values are compared with each other and with catalogued values of duration and V/Vmax

A Quantum-Bayesian Route to Quantum-State Space

In the quantum-Bayesian approach to quantum foundations, a quantum state is viewed as an expression of an agent's personalist Bayesian degrees of belief, or probabilities, concerning the results of measurements. These probabilities obey the usual probability rules as required by Dutch-book coherence, but quantum mechanics imposes additional constraints upon them. In this paper, we explore the question of deriving the structure of quantum-state space from a set of assumptions in the spirit of quantum Bayesianism. The starting point is the representation of quantum states induced by a symmetric informationally complete measurement or SIC. In this representation, the Born rule takes the form of a particularly simple modification of the law of total probability. We show how to derive key features of quantum-state space from (i) the requirement that the Born rule arises as a simple modification of the law of total probability and (ii) a limited number of additional assumptions of a strong Bayesian flavor.Comment: 7 pages, 1 figure, to appear in Foundations of Physics; this is a condensation of the argument in arXiv:0906.2187v1 [quant-ph], with special attention paid to making all assumptions explici

Spatio-temporal dynamics of quantum-well excitons

We investigate the lateral transport of excitons in ZnSe quantum wells by using time-resolved micro-photoluminescence enhanced by the introduction of a solid immersion lens. The spatial and temporal resolutions are 200 nm and 5 ps, respectively. Strong deviation from classical diffusion is observed up to 400 ps. This feature is attributed to the hot-exciton effects, consistent with previous experiments under cw excitation. The coupled transport-relaxation process of hot excitons is modelled by Monte Carlo simulation. We prove that two basic assumptions typically accepted in photoluminescence investigations on excitonic transport, namely (i) the classical diffusion model as well as (ii) the equivalence between the temporal and spatial evolution of the exciton population and of the measured photoluminescence, are not valid for low-temperature experiments.Comment: 8 pages, 6 figure

The Case for Banning (and Mandating) Ransomware Insurance

Ransomware attacks are becoming increasingly pervasive and disruptive, resulting in ransom demands becoming more exorbitant. Payments for ransom costs are increasingly being covered by insurance, which may offer coverage for a variety of cyber-related losses. Some commentators have expressed concern over this market phenomenon. Specifically, the concern is that the presence of insurance is making the ransomware problem worse based on the following theory: because there is ransomware insurance that covers ransom payments, and because paying the ransom is often far cheaper than paying the restoration and business interruption costs covered under the policy, there is an increased tendency to pay the ransom—and a willingness to pay higher amounts. This fact, known by the criminals, increases their incentive to engage in ransomware attacks, which increases the demand for insurance. And the cycle continues. This Article demonstrates that the picture is not as simple as this story would suggest. Insurance offers a variety of pre-breach and postbreach services that are aimed at reducing the likelihood and severity of a ransomware attack. Thus, over the long-term, cyber insurance has the potential to lower ransomware-related costs, even without government intervention. As recent research has shown, however, insurers have not yet fully embraced their potential role as ex ante and ex post regulators of cyber risk—a role for which they are especially well-suited. This Article discusses reasons why that might be the case and offers suggestions for how government intervention may help. Among these suggestions is a limited ban on indemnity for ransomware payments with exceptions for cases involving threats to life and limb, which would be an expanded version of what is already in place with the Office of Foreign Assets Control’s (“OFAC”) sanctions program. We also explain how a government regulator, such as the OFAC, could serve a coordinating function to help cyber insurers internalize the externalities associated with the insurers’ decisions to reimburse ransomware payments—a role that is played by reinsurers in the context of kidnap-and-ransom insurance. Finally, we consider the idea of a federal mandate requiring property and casualty insurers to provide coverage for the costs of ransomware attacks but exclude coverage for the ransomware payments

Genes as Tags: The Tax Implications of Widely Available Genetic Information

This paper examines how progress in genetics\u27 specifically, the proliferation of knowledge about the human genome\u27 may influence the feasibility and desirability of a tax that is based on individual human endowments or ability. The paper explores various forms that such a genetic endowment tax-and-transfer regime might take and identifies some of the benefits and costs of such a regime. The authors take no position on whether a genetic endowment tax would be desirable or not. However, one contribution of the paper is to observe that current law in the U.S., which restricts the use of genetic information by insurers and employers, is equivalent to a form of genetic endowment tax. The paper also notes that, in the absence of a government-mandated transfer policy with respect to genetic endowments, private insurance markets may arise to fill the gap, allowing individuals to purchase insurance against the possibility of a bad genetic draw

Of Coase, Calabresi, and Optimal Tax Liability

The Coase Theorem and the vast literature it inspired explore two basic questions: to whom should responsibility for external harms be assigned and how will that assignment matter. Building on the Coasean insight in the torts context, Guido Calabresi observed that the assignment of tort liability can indeed matter from an efficiency perspective and should, under certain assumptions, be assigned to the “cheapest cost avoider.” This article applies a similar Coasean/Calabresian framework to a related (though not identical) set of questions in the tax context: To whom should the responsibility for remitting taxes be assigned and when and how will that assignment matter? Following Calabresi’s canonical formulation for the design of an optimal tort system, we conclude that an optimal tax remittance regime requires that tax liabilities be assigned so as to minimize the overall social costs of compliance and administration for a given level of achievement of the tax law’s desired distributional and revenue goals. This will sometimes mean assigning tax remittance responsibility to the lowest-compliance-cost remitter, and other times not – if that party happens also to be the lowest-cost liability avoider (the party best able to evade the tax). This comparison of tax remittance responsibility and tort remittance responsibility produces a number of positive and normative insights. For example, it helps to explain why the remittance responsibility for the retail sales tax lies primarily with the sellers rather than the buyers, as well as why we have wage withholding for the income tax. And it helps to explain some existing types of non-wage withholding, such as withholding on payments to foreign taxpayers. This framework also supports a number of reforms in the current U.S. regime for tax enforcement such as expanding the withholding requirement to payments made to independent contractors, which are a type of payment that currently contributes significantly to the overall U.S. federal tax gap

The Case for Banning (and Mandating) Ransomware Insurance

Ransomware attacks are becoming increasingly pervasive and disruptive. Not only are they shutting down (or at least “holding up”) businesses and local governments all around the country, they are disrupting institutions in many sectors of the U.S. economy — from school systems, to medical facilities, to critical elements of the U.S. energy infrastructure as well as the food supply chain. Ransomware attacks are also growing more frequent and the ransom demands more exorbitant. Those ransom payments are increasingly being covered by insurance. That insurance offers coverage for a variety of cyber-related losses, including many of the costs arising out of ransomware attacks, such as the costs of hiring expert negotiators, the costs of recovering data from backups, the legal liabilities for exposing sensitive customer information, and the ransom payments themselves. Some commentators have expressed concern with this market phenomenon. Specifically, the concern is that the presence of insurance is making the ransomware problem worse, on the following theory: Because there is ransomware insurance that covers ransom payments, and because paying the ransom is often far cheaper than paying the restoration costs and business interruption costs also covered under the policy, there is an increased tendency to pay the ransom — and a willingness to pay higher amounts. This fact, known by the criminals, increases their incentive to engage in ransomware attacks in the first place. And the demand for insurance increases; and the cycle continues. This Article demonstrates that the picture is not as simple as thi story would suggest. Insurance offers a variety of pre-breach and post-breach services that are aimed at reducing the likelihood and severity of a ransomware attack. Thus, over the long-term, cyber insurance has the potential to lower ransomware-related costs. But we are not there yet. This Article discusses ways to help ensure that ransomware insurance is a force for good. Among our suggestions are a limited ban on indemnity for ransomware payments with exceptions for cases involving threats to life and limb, coupled with a mandate that property/casualty insurers provide coverage for the other costs of ransomware attacks. We also explain how a government regulator could serve a coordinating function to help cyber insurers internalize the externalities associated with the insurers’ decisions to reimburse ransomware payments, a role that is played by reinsurers in the context of Kidnap-and-ransom insurance

Genetic determinants of cortical structure (thickness, surface area and volumes) among disease free adults in the CHARGE Consortium

Cortical thickness, surface area and volumes (MRI cortical measures) vary with age and cognitive function, and in neurological and psychiatric diseases. We examined heritability, genetic correlations and genome-wide associations of cortical measures across the whole cortex, and in 34 anatomically predefined regions. Our discovery sample comprised 22,824 individuals from 20 cohorts within the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium and the United Kingdom Biobank. Significant associations were replicated in the Enhancing Neuroimaging Genetics through Meta-analysis (ENIGMA) consortium, and their biological implications explored using bioinformatic annotation and pathway analyses. We identified genetic heterogeneity between cortical measures and brain regions, and 160 genome-wide significant associations pointing to wnt/β-catenin, TGF-β and sonic hedgehog pathways. There was enrichment for genes involved in anthropometric traits, hindbrain development, vascular and neurodegenerative disease and psychiatric conditions. These data are a rich resource for studies of the biological mechanisms behind cortical development and aging

International meta-analysis of PTSD genome-wide association studies identifies sex- and ancestry-specific genetic risk loci.

The risk of posttraumatic stress disorder (PTSD) following trauma is heritable, but robust common variants have yet to be identified. In a multi-ethnic cohort including over 30,000 PTSD cases and 170,000 controls we conduct a genome-wide association study of PTSD. We demonstrate SNP-based heritability estimates of 5-20%, varying by sex. Three genome-wide significant loci are identified, 2 in European and 1 in African-ancestry analyses. Analyses stratified by sex implicate 3 additional loci in men. Along with other novel genes and non-coding RNAs, a Parkinson's disease gene involved in dopamine regulation, PARK2, is associated with PTSD. Finally, we demonstrate that polygenic risk for PTSD is significantly predictive of re-experiencing symptoms in the Million Veteran Program dataset, although specific loci did not replicate. These results demonstrate the role of genetic variation in the biology of risk for PTSD and highlight the necessity of conducting sex-stratified analyses and expanding GWAS beyond European ancestry populations

ENIGMA and global neuroscience: A decade of large-scale studies of the brain in health and disease across more than 40 countries

This review summarizes the last decade of work by the ENIGMA (Enhancing NeuroImaging Genetics through Meta Analysis) Consortium, a global alliance of over 1400 scientists across 43 countries, studying the human brain in health and disease. Building on large-scale genetic studies that discovered the first robustly replicated genetic loci associated with brain metrics, ENIGMA has diversified into over 50 working groups (WGs), pooling worldwide data and expertise to answer fundamental questions in neuroscience, psychiatry, neurology, and genetics. Most ENIGMA WGs focus on specific psychiatric and neurological conditions, other WGs study normal variation due to sex and gender differences, or development and aging; still other WGs develop methodological pipelines and tools to facilitate harmonized analyses of "big data" (i.e., genetic and epigenetic data, multimodal MRI, and electroencephalography data). These international efforts have yielded the largest neuroimaging studies to date in schizophrenia, bipolar disorder, major depressive disorder, post-traumatic stress disorder, substance use disorders, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, autism spectrum disorders, epilepsy, and 22q11.2 deletion syndrome. More recent ENIGMA WGs have formed to study anxiety disorders, suicidal thoughts and behavior, sleep and insomnia, eating disorders, irritability, brain injury, antisocial personality and conduct disorder, and dissociative identity disorder. Here, we summarize the first decade of ENIGMA's activities and ongoing projects, and describe the successes and challenges encountered along the way. We highlight the advantages of collaborative large-scale coordinated data analyses for testing reproducibility and robustness of findings, offering the opportunity to identify brain systems involved in clinical syndromes across diverse samples and associated genetic, environmental, demographic, cognitive, and psychosocial factors