Anharmonic multi-phonon nonradiative transition: An ab initio calculation approach

Nonradiative carrier recombinations at deep centers in semiconductors are of great importance for both fundamental physics and device engineering. In this article, we provide a revised analysis of Huang’s original nonradiative multi-phonon (NMP) theory with ab initio calculations. First, we confirmed at the first-principles level that Huang’s concise formula gives the same results as the matrix-based formula, and that Huang’s high-temperature formula provides an analytical expression for the coupling constant in Marcus theory. Secondly, we correct for anharmonic effects by taking into account local phonon-mode variations for different charge states of a defect. The corrected capture rates for defects in GaN and SiC agree well with experiments

On staying grounded and avoiding Quixotic dead ends

The 15 articles in this special issue on The Representation of Concepts illustrate the rich variety of theoretical positions and supporting research that characterize the area. Although much agreement exists among contributors, much disagreement exists as well, especially about the roles of grounding and abstraction in conceptual processing. I first review theoretical approaches raised in these articles that I believe are Quixotic dead ends, namely, approaches that are principled and inspired but likely to fail. In the process, I review various theories of amodal symbols, their distortions of grounded theories, and fallacies in the evidence used to support them. Incorporating further contributions across articles, I then sketch a theoretical approach that I believe is likely to be successful, which includes grounding, abstraction, flexibility, explaining classic conceptual phenomena, and making contact with real-world situations. This account further proposes that (1) a key element of grounding is neural reuse, (2) abstraction takes the forms of multimodal compression, distilled abstraction, and distributed linguistic representation (but not amodal symbols), and (3) flexible context-dependent representations are a hallmark of conceptual processing

The nonlinear Bernstein-Schr\"odinger equation in Economics

In this paper we relate the Equilibrium Assignment Problem (EAP), which is underlying in several economics models, to a system of nonlinear equations that we call the "nonlinear Bernstein-Schr\"odinger system", which is well-known in the linear case, but whose nonlinear extension does not seem to have been studied. We apply this connection to derive an existence result for the EAP, and an efficient computational method.Comment: 8 pages, submitted to Lecture Notes in Computer Scienc

Nanoimaging of Organic Charge Retention Effects: Implications for Nonvolatile Memory, Neuromorphic Computing, and High Dielectric Breakdown Devices

While a large variety of organic and molecular materials have been found to exhibit charge memory effects, the underlying mechanism is not well-understood, which hinders rational device design. Here, we study the charge retention mechanism of a nanoscale memory system, an organic monolayer on a silicon substrate, with Au nanoparticles on top serving as the electrical contact. Combining scanning probe imaging/manipulation and density functional simulations, we observe stable charge retention effects in the system and attributed it to polaron effects at the amine functional groups. Our findings can pave the way for applications in nonvolatile memory, neuromorphic computing, and high dielectric breakdown devices

Dating Nathan: The Oldest Stained Glass Window in England?

Relatively little is known about stained glass windows in England predating c. 1170; however, art-historical evaluation by Caviness (1987) argued that four figures from the “Ancestors series” of Canterbury Cathedral, usually dated to the late 12th and early 13th century, in fact date earlier (c. 1130–1160). This would place them amongst the earliest stained glass in England, and the world. Building on our previous work, we address Caviness’s hypothesis using a methodology based upon analysis of a few, well-measured heavy trace elements and a 3D-printed attachment for a pXRF spectrometer that facilitates in situ analysis. The results confirm two major periods of “recycling” or re-using medieval glass. The first is consistent with Caviness’s argument that figures predating the 1174 fire were reused in the early 13th century. The results suggest that in addition to figures, ornamental borders were reused, indicating the presence of more early glass than previously thought. In the second period of recycling (1790s), surviving figures from the Ancestors series were removed and adapted into rectangular panels for insertion into large Perpendicular-style windows elsewhere in the cathedral. The results show that the glasses used to adapt the panels to a rectangular shape were broadly contemporary with the glasses used to glaze the original Ancestors windows, again representing a more extensive presence of medieval glass in the windows

Targeting Escalation in Intimate Partner Violence: Evidence from 52,000 Offenders

Research Question Does the severity or frequency of intimate partner violence or abuse reported to police increase over time, once a unique perpetrator-victim couple has come into contact with police in Thames Valley UK? Data A total of 140,998 recent (non-historical) incidents of intimate partner violence or abuse reported to Thames Valley Police in 2010-2015 were identified, with 52,296 unique perpetrators for whom a standard 731-day observation period was possible after each perpetrator’s first incident was reported in the intake period from 1st January 2010 through 31st December. Duplicate entries were eliminated and standard eligibility criteria were assured by data-cleaning from the NICHE records management system of Thames Valley Police. Methods All non-crime incidents or reports of crime against intimate partners were coded by the Cambridge Crime Harm Index (CHI) with the sum of total days of recommended imprisonment for each offence (as the guideline starting point for sentencing) summed across all offences for each offender (Sherman, et al 2016), with CHI scores for each successive incident plotted in sequence. Prevalence and frequency of repeat police contacts were also computed for each perpetrator, as well as the conditional probability of each new offence given the number of prior offences. Findings Most perpetrators identified in the 52,296 initial reports (77.6%) had no report of crime after the initial report. A further 21.2% had crime harm totals of less than 10 days of recommended prison time, with only 893 (1.7%) of the total universe of four years’ worth of perpetrators who had a reported crime harm total over offences with a recommendation of over 10 days sentencing in the 731-day observation period. A slightly larger “power few” of 3% of perpetrators accounted for 90% of total intimate partner abuse crime harm inflicted by all perpetrators, while 97% of perpetrators produced only 10% of total crime harm. Overall, among the few who had numerous repeat incidents, there was increasing frequency but no evidence of increasing seriousness of harm caused to victims. The 100 most harmful offenders in 2010 maintained a high (but greatly decreased) level of harm in 2011, but on average were very-low harm offenders in 2012-15. Conclusions This analysis suggests that the intimate partner abuser population is highly segmented in Thames Valley, with a small power few inflicting most of the harm. While the most serious offenders may remain difficult to identify prospectively, any valid prediction model could help to prevent a substantial amount of crime harm against intimate partners. Investing in such prediction methods may do more to help victims than an undifferentiated strategy putting most resources into low-risk cases. Keywords Intimate partner violence – policing –Crime Harm Index—Forecasting High Har

Species-specific differences in the expression of the HNF1A, HNF1B and HNF4A genes

addresses: Institute of Biomedical and Clinical Sciences, Peninsula Medical School, University of Exeter, Exeter, United Kingdom. [email protected]: PMCID: PMC2773013types: Journal Article; Research Support, Non-U.S. Gov'tCopyright: © 2009 Harries et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.The HNF1A, HNF1B and HNF4A genes are part of an autoregulatory network in mammalian pancreas, liver, kidney and gut. The layout of this network appears to be similar in rodents and humans, but inactivation of HNF1A, HNF1B or HNF4A genes in animal models cause divergent phenotypes to those seen in man. We hypothesised that some differences may arise from variation in the expression profile of alternatively processed isoforms between species

Do Gang Injunctions Reduce Violent Crime? Four Tests in Merseyside, UK

Research Question: Did gang members and gangs named by police in four separate court-ordered 24-month injunctions, issued at different times, reduce the frequency and harm of crimes they committed, and suffer fewer crimes against themselves as well? Data: The study examined criminal histories of 36 members of four gangs for a 36-month period before and a 36-month period after their respective injunctions. Data also included records of crimes committed against the gang members in the same time periods. Criminal activity was measured by arrests, station interviews, fixed penalty notices and summonses. Days offenders spent in custody, which rose during the gang injunction periods, were removed from denominators calculating rates, so that the estimates of changes in offender behaviour and victimisations are all based on their days at liberty and out of prison or jail. Methods: The study compared the magnitude of change in both individual-level and gang-level measures of crime and victimisation from before to after the issuance of the injunction as ‘natural quasi-experiments’, with comparisons made to other gangs in Liverpool which had not been subjects of injunctions. Findings: Across all 36 gang members, their individual offending counts dropped by 70% in the 3 years after their gang injunctions, while the Cambridge Crime Harm Index weight of the seriousness of their total crimes dropped by 61%. Fewer criminal events were attributed to 92% of the individuals in the second 3-year period than in the first, while only 8% increased their detected activity. Taking the four gangs as the unit of analysis, their offences dropped by 74% in the 3 years after the injunctions, while their Crime Harm Index weight dropped by 70%. Victimisation of the gang members in their 3-year post-injunction period dropped by 60% compared to the pre-injunction period. Comparisons between gangs with injunctions and gangs without showed downward crime trends in the injunction gangs that were not observed in the comparisons during the same time periods, but regression to the mean could not be ruled out as an explanation for the findings. Conclusions: The evidence for the effectiveness of gang injunctions in reducing crime harm is stronger than the evidence for most police practices. There is no evidence in this study of these injunctions causing crime to increase. Police agencies may be encouraged to use such powers when available, as long as they track the trends with sufficient care to detect any potential backfire effects