Compliance with Police: Does the Interaction of Race/Ethnicity and Sex Matter?

The often controversial nature of police use of force continues to cast law enforcement in a negative light, increasing an already historically tense relationship between law enforcement and the communities they serve. As cases of police brutality continue to surface, the legitimacy of police personnel continues to decrease, but community member behaviors toward officers are infrequently explored. Questions about the influence of situational, legal, and officer/community member characteristics arise in an attempt to further explore how these factors influence community member compliance. Thus, this study aims to understand police-community relations more clearly, focusing on the effects, if any, that the community member and officer’s sex, race, and ethnicity have regarding police requests. Using data from the 2015 Police Public Contact Survey (PPCS), respondents’ experiences with police officers are used to assess compliance behaviors. Findings suggest that situational and legal characteristics have larger significance regarding compliance than officer and community member characteristics. Therefore, increasing the legitimacy of police departments and the trust that community members have with officers is more essential in increasing voluntary compliance

Early Childhood Brain Development

Includes bibliographical references.We know that children need proper nutrition, safe homes, access to health care, and good parenting in order to thrive. With recent technological advances, we are also beginning to understand more about how a child's brain develops and what we can do to promote optimal brain development

EPR identification of defects responsible for thermoluminescence in Cu-doped lithium tetraborate (Li2B4O7) crystals

Electron paramagnetic resonance (EPR) is used to identify the electron and hole traps responsible for thermoluminescence (TL) peaks occurring near 100 and 200 ◦C in copper-doped lithium tetraborate (Li2B4O7) crystals. As-grown crystals have Cu+ and Cu2+ ions substituting for lithium and have Cu+ ions at interstitial sites. All of the substitutional Cu2+ ions in the as-grown crystals have an adjacent lithium vacancy and give rise to a distinct EPR spectrum. Exposure to ionizing radiation at room temperature produces a second and different Cu2+ EPR spectrum when a hole is trapped by substitutional Cu+ ions that have no nearby defects. These two Cu2+ trapped-hole centers are referred to as Cu2+-VLi and Cu2+active, respectively. Also during the irradiation, two trapped-electron centers in the form of interstitial Cu0 atoms are produced when interstitial Cu+ ions trap electrons. They are observed with EPR and are labeled Cu0A and Cu0B. When an irradiated crystal is warmed from 25 to 150 ◦C, the Cu2+active centers have a partial decay step that correlates with the TL peak near 100 ◦C. The concentrations of Cu0A and Cu0B centers, however, increase as the crystal is heated through this range. As the crystal is futher warmed between 150 and 250 ◦C, the EPR signals from the Cu2+active hole centers and Cu0A and Cu0B electron centers decay simultaneously. This decay step correlates with the intense TL peak near 200 ◦C

Photoconductivity Parameters In Lithium Niobate

Measurements on a variety of doped (magnesium and/or iron) and undoped lithium niobate crystals in the oxidized state demonstrate an Arrhenius dependence of dark conductivity on reciprocal temperature between 460 and 590 K. All of the crystals had roughly the same conductivity and activation energy (1.21 eV) over the temperature range, implying that all have about the same free-carrier concentration and mobility. The enhanced photoconductivity of magnesium-doped lithium niobate is attributed to a greatly reduced trapping cross section of Fe3+ for electrons, the smaller cross section being due to a changed substitutional site for Fe3+. The Fe3+ trapping cross section is calculated from photoconductivity data to be of order 10-18 m2 in undoped lithium niobate. This implies a photoelectron lifetime of order 6x10-11 s in a relatively pure (2-ppm Fe) oxidized crystal

Threshold Effect In Mg-doped Lithium Niobate

Optical absorption spectra were obtained after reducing (i.e., vacuum annealing) a series of LiNbO3 crystals grown from melts having various Mg concentrations and Li/Nb ratios. A band peaking at 500 nm, and assigned to oxygen vacancies containing two electrons, was the only absorption present in one set of crystals following reduction. In contrast, two overlapping bands peaking near 1200 and 760 nm were present in the other set of crystals immediately after the reduction. The 1200-nm band is assigned to a previously unreported electron trap and the 760-nm band to oxygen vacancies containing only one electron. These data are interpreted in terms of a threshold level for Mg doping; however, the threshold Mg doping level is not a constant but depends on the ratio of Mg ions to Li vacancies

Observation Of Singly Ionized Selenium Vacancies In Znse Grown By Molecular Beam Epitaxy

Electron paramagnetic resonance(EPR) has been used to investigate singly ionized selenium vacancy V Se + centers in ZnSe epilayers grown by molecular beam epitaxy(MBE). The study included undoped and nitrogen-doped films. Spectra taken at 8 K and 9.45 GHz, as the magnetic field was rotated in the plane from [100] to [010], showed an isotropic signal at g =2.0027±0.0004 with a linewidth of 5.8 G. In the two samples where this signal was observed, estimates of concentration were approximately 1.1×10 17 and 6.3×10 17 cm −3 . The appearance of the EPR signal correlated with an increase in the Zn/Se beam equivalent pressure ratio (during growth) in undoped films and with an increase in the nitrogen concentration in doped films. We conclude that the singly ionized selenium vacancy may be a dominant point defect in many MBE-grown ZnSe layers and that these defects may play a role in the compensation mechanisms in heavily nitrogen-doped ZnSe thin films

Electron paramagnetic resonance and optical absorption study of acceptors in CdSiP2 crystals

Cadmium silicon diphosphide (CdSiP2) is a nonlinear material often used in optical parametric oscillators (OPOs) to produce tunable laser output in the mid-infrared. Absorption bands associated with donors and acceptors may overlap the pump wave- length and adversely affect the performance of these OPOs. In the present investigation, electron paramagnetic resonance (EPR) is used to identify two unintentionally present acceptors in large CdSiP2 crystals. These are an intrinsic silicon-on-phosphorus anti- site and a copper impurity substituting for cadmium. When exposed to 633 nm laser light at temperatures near or below 80 K, they convert to their neutral paramagnetic charge states (Si0P and Cu0Cd) and can be monitored with EPR. The corresponding donor serving as the electron trap is the silicon-on-cadmium antisite (Si2+ before illumina- above 90 K quickly destroys the EPR signals from both acceptors and the associated donor. Broad optical absorption bands peaking near 0.8 and 1.4 μm are also pro- duced at low temperature by the 633 nm light. These absorption bands are associated with the Si0P and Cu0Cd acceptors. © 2018 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). https://doi.org/10.1063/1.504180

Transition-metal ions in β-Ga\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e crystals: Identification of Ni acceptors

Excerpt: Transition-metal ions (Ni, Cu, and Zn) in β-Ga2O3 crystals form deep acceptor levels in the lower half of the bandgap. In the present study, we characterize the Ni acceptors in a Czochralski-grown crystal and find that their (0/−) level is approximately 1.40 eV above the maximum of the valence band

EPR identification of defects responsible for thermoluminescence in Cu-doped lithium tetraborate (Li2B4O7) crystals

Electron paramagnetic resonance (EPR) is used to identify the electron and hole traps responsible for thermoluminescence (TL) peaks occurring near 100 and 200 ◦C in copper-doped lithium tetraborate (Li2B4O7) crystals. As-grown crystals have Cu+ and Cu2+ ions substituting for lithium and have Cu+ ions at interstitial sites. All of the substitutional Cu2+ ions in the as-grown crystals have an adjacent lithium vacancy and give rise to a distinct EPR spectrum. Exposure to ionizing radiation at room temperature produces a second and different Cu2+ EPR spectrum when a hole is trapped by substitutional Cu+ ions that have no nearby defects. These two Cu2+ trapped-hole centers are referred to as Cu2+-VLi and Cu2+active, respectively. Also during the irradiation, two trapped-electron centers in the form of interstitial Cu0 atoms are produced when interstitial Cu+ ions trap electrons. They are observed with EPR and are labeled Cu0A and Cu0B. When an irradiated crystal is warmed from 25 to 150 ◦C, the Cu2+active centers have a partial decay step that correlates with the TL peak near 100 ◦C. The concentrations of Cu0A and Cu0B centers, however, increase as the crystal is heated through this range. As the crystal is futher warmed between 150 and 250 ◦C, the EPR signals from the Cu2+active hole centers and Cu0A and Cu0B electron centers decay simultaneously. This decay step correlates with the intense TL peak near 200 ◦C