1,381 research outputs found
Command-level Police Officersâ Perceptions of the âWar on Copsâ and De-policing
Policing has been the subject of intense public scrutiny for the better part of two years after several high-profile police killings of unarmed African Americans across the United States. The scrutiny has been so extreme that some contend there is currently a âwar on copsââwhereby citizens are emboldened by protests and negative media coverage of the police, and are lashing out by assaulting police officers more frequently. In response, it is argued that officers are de-policing (i.e. avoiding proactive stops). We surveyed command-level police officers from a southeastern state about their attitudes concerning the war on cops and de-policing. The majority of our sample believed there has been a war on cops over the last two years. Moreover, officers who felt strongly about the existence of a war on cops were more likely to believe that de-policing is common among officers in todayâs world of law enforcement
Affordable, Energy-Efficient Housing Design for Chile: Achieving Passivhaus Standard with the Chilean State Housing Subsidy
In Chile, it is estimated that the energy demand will continue to increase if substantial energy efficiency measures in housing are not taken. These measures are generally associated with technical and mainly economic difficulties. This paper aims to show the technical and economic feasibility of achieving Passivhaus standard house in Chile, considering the budget of the maximum state subsidy currently available (Chilean Unidad de Fomento (CLF) 2000 â 81,000 USD). The design was simulated in the Passive House Planning Package software to determine if the house could be certified with the selected standard. At the same time, the value of all the items was quantified in order not to exceed the stipulated maximum budget for a house considered as affordable. It was shown that in terms of design it is possible to implement the Passivhaus standard given the current housing subsidy. The designed housing ensures a reduction of 85% in heating demand and a 60% reduction in CO2 emissions during the operation, compared to an average typical Chilean house
Demeanor, Race, and Police Perceptions of Procedural Justice: Evidence from Two Randomized Experiments
President Obamaâs Task Force on 21st Century Policing recently endorsed procedural justice as a way to restore trust between police and communities. Yet policeâcitizen interactions vary immensely, and research has yet to give sufficient consideration to the factors that might affect the importance officers place on exercising procedural justice during interactions. Building on research examining âmoral worthinessâ judgments and racial stereotyping among police officers, we conducted two randomized experiments to test whether suspect race and demeanor affect officersâ perceptions of the threat of violence and importance of exercising procedural justice while interacting with suspicious persons. We find that suspect race fails to exert a statistically significant effect on either outcome. However, demeanor doesâsuch that officers perceive a greater threat of violence and indicate it is less important to exercise procedural justice with disrespectful suspects. These findings have implications for procedural justice training, specifically, and policeâcommunity relations more broadly
Reprogramming the Maternal Zebrafish Genome after Fertilization to Match the Paternal Methylation Pattern
SummaryEarly vertebrate embryos must achieve totipotency and prepare for zygotic genome activation (ZGA). To understand this process, we determined the DNA methylation (DNAme) profiles of zebrafish gametes, embryos at different stages, and somatic muscle and compared them to gene activity and histone modifications. Sperm chromatin patterns are virtually identical to those at ZGA. Unexpectedly, the DNA of many oocyte genes important for germline functions (i.e., piwil1) or early development (i.e., hox genes) is methylated, but the loci are demethylated during zygotic cleavage stages to precisely the state observed in sperm, even in parthenogenetic embryos lacking a replicating paternal genome. Furthermore, this cohort constitutes the genes and loci that acquire DNAme during development (i.e., ZGA to muscle). Finally, DNA methyltransferase inhibition experiments suggest that DNAme silences particular gene and chromatin cohorts at ZGA, preventing their precocious expression. Thus, zebrafish achieve a totipotent chromatin state at ZGA through paternal genome competency and maternal genome DNAme reprogramming
Final Report: Buffalo National River Ecosystems
The objective of this study was to sample the Buffalo River on a seasonal basis for a year, in order to determine whether any potential water quality problems existed
Statistical Model of Heavy-Ion Fusion-Fission Reactions
Cross-section and neutron-emission data from heavy-ion fusion-fission
reactions are consistent with the fission of fully equilibrated systems with
fission lifetime estimates obtained via a Kramers-modified statistical model
which takes into account the collective motion of the system about the ground
state, the temperature dependence of the location and height of fission
transition points, and the orientation degree of freedom. If the standard
techniques for calculating fission lifetimes are used, then the calculated
excitation-energy dependence of fission lifetimes is incorrect. We see no
evidence to suggest that the nuclear viscosity has a temperature dependence.
The strong increase in the nuclear viscosity above a temperature of
approximately 1.3 MeV deduced by others is an artifact generated by an
inadequate fission model.Comment: Full paper submitted to PRC to accompany our recently published Phys.
Rev. Lett. 101, 032702 (2008
Genetic algorithm dynamics on a rugged landscape
The genetic algorithm is an optimization procedure motivated by biological
evolution and is successfully applied to optimization problems in different
areas. A statistical mechanics model for its dynamics is proposed based on the
parent-child fitness correlation of the genetic operators, making it applicable
to general fitness landscapes. It is compared to a recent model based on a
maximum entropy ansatz. Finally it is applied to modeling the dynamics of a
genetic algorithm on the rugged fitness landscape of the NK model.Comment: 10 pages RevTeX, 4 figures PostScrip
Audio source separation using hierarchical phase-invariant models
2009 ISCA Tutorial and Research Workshop on Non-linear Speech Processing (NOLISP)International audienceAudio source separation consists of analyzing a given audio recording so as to estimate the signal produced by each sound source for listening or information retrieval purposes. In the last five years, algorithms based on hierarchical phase-invariant models such as single or multichannel hidden Markov models (HMMs) or nonnegative matrix factorization (NMF) have become popular. In this paper, we provide an overview of these models and discuss their advantages compared to established algorithms such as nongaussianity-based frequency-domain independent component analysis (FDICA) and sparse component analysis (SCA) for the separation of complex mixtures involving many sources or reverberation.We argue how hierarchical phase-invariant modeling could form the basis of future modular source separation systems
Memory effects on descent from nuclear fission barrier
Non-Markovian transport equations for nuclear large amplitude motion are
derived from the collisional kinetic equation. The memory effects are caused by
the Fermi surface distortions and depend on the relaxation time. It is shown
that the nuclear collective motion and the nuclear fission are influenced
strongly by the memory effects at the relaxation time . In particular, the descent of the nucleus from the fission
barrier is accompanied by characteristic shape oscillations. The eigenfrequency
and the damping of the shape oscillations depend on the contribution of the
memory integral in the equations of motion. The shape oscillations disappear at
the short relaxation time regime at , which corresponds to the
usual Markovian motion in the presence of friction forces. We show that the
elastic forces produced by the memory integral lead to a significant delay for
the descent of the nucleus from the barrier. Numerical calculations for the
nucleus U shows that due to the memory effect the saddle-to-scission
time grows by a factor of about 3 with respect to the corresponding
saddle-to-scission time obtained in liquid drop model calculations with
friction forces.Comment: 22 pages, 8 figures, submitted to Phys. Rev.
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