2,068 research outputs found
Language from Police Body Camera Footage Shows Racial Disparities in Officer Respect
Using footage from body-worn cameras, we analyze the respectfulness of police officer language toward white and black community members during routine traffic stops. We develop computational linguistic methods that extract levels of respect automatically from transcripts, informed by a thin-slicing study of participant ratings of officer utterances. We find that officers speak with consistently less respect toward black versus white community members, even after controlling for the race of the officer, the severity of the infraction, the location of the stop, and the outcome of the stop. Such disparities in common, everyday interactions between police and the communities they serve have important implications for procedural justice and the building of police–community trust
Preclinical PET and MR Evaluation of 89Zr- and 68Ga-Labeled Nanodiamonds in Mice over Different Time Scales
Nanodiamonds (NDs) have high potential as a drug carrier and in combination with nitrogen vacancies (NV centers) for highly sensitive MR-imaging after hyperpolarization. However, little remains known about their physiological properties in vivo. PET imaging allows further evaluation due to its quantitative properties and high sensitivity. Thus, we aimed to create a preclinical platform for PET and MR evaluation of surface-modified NDs by radiolabeling with both short- and long-lived radiotracers. Serum albumin coated NDs, functionalized with PEG groups and the chelator deferoxamine, were labeled either with zirconium-89 or gallium-68. Their biodistribution was assessed in two different mouse strains. PET scans were performed at various time points up to 7 d after i.v. injection. Anatomical correlation was provided by additional MRI in a subset of animals. PET results were validated by ex vivo quantification of the excised organs using a gamma counter. Radiolabeled NDs accumulated rapidly in the liver and spleen with a slight increase over time, while rapid washout from the blood pool was observed. Significant differences between the investigated radionuclides were only observed for the spleen (1 h). In summary, we successfully created a preclinical PET and MR imaging platform for the evaluation of the biodistribution of NDs over different time scales
About the strength of correlation effects in the electronic structure of iron
The strength of electronic correlation effects in the spin-dependent
electronic structure of ferromagnetic bcc Fe(110) has been investigated by
means of spin and angle-resolved photoemission spectroscopy. The experimental
results are compared to theoretical calculations within the three-body
scattering approximation and within the dynamical mean-field theory, together
with one-step model calculations of the photoemission process. This comparison
indicates that the present state of the art many-body calculations, although
improving the description of correlation effects in Fe, give too small mass
renormalizations and scattering rates thus demanding more refined many-body
theories including non-local fluctuations.Comment: 4 pages, 4 figure
Profile and quality of life of patients with esophageal and gastric cancers = Perfil e qualidade de vida de pacientes com câncer de esôfago e de estômago
Wetland Bird Abundance and Safety Implications for Military Aircraft Operations
Wetlands with associated avifauna can pose a substantial hazard to aviation safety, potentially increasing bird–aircraft collision (strike) risk when located near air operations areas.We modeled year-round use by wetland avifauna of Drummond Flats Wildlife Management Area (Drummond Flats), a wetland complex located within 10 km of Vance Air Force Base (AFB), Enid, Oklahoma, USA. Our objectives were to 1) quantify seasonal avifauna abundances at Drummond Flats; 2) test a priori models reflecting use by bird species recognized as hazardous to aviation safety relative to environmental factors including flooded wetland habitat and vegetation cover; 3) use these models to predict maximal expected abundances of wetland avifauna during flood conditions; and 4) compare our findings with reported bird strikes at Vance AFB. Drought conditions influenced avian use during our study. Of the species expected to respond predictably to flooded wetland habitat, only ducks (Anatinae) occurred in numbers conducive to modeling. Using zero inflated Poisson models, we found that duck abundance was positively associated with permanent wetland habitat type and, excluding winter, available habitat area (i.e., standing water); whereas, \u3e50% vegetation cover was negatively correlated with abundance. No model predicted \u3e97.2 ducks/ha for any habitat type, except during winter. Our models also identified potential peaks in abundance not evident from raw count data, emphasizing the benefits of this approach. Identifying factors driving abundances also enables targeted management of hazardous species. Further, we found double-sampling to be a practical method for assessing detection bias during avian surveys at wetlands. Restricting to obligate wetland species associated with Drummond Flats, we found 1 strike/184,212 flight-hours, which was an order of magnitude lower than the average for U.S. civil aircraft (1990–2014). Thus, under drought conditions, bird use of Drummond Flats likely did not elevate strike risk for Vance AFB aircraft operations
Probing the Early Stages of Low-Mass Star Formation in LDN 1689N: Dust and Water in IRAS 16293-2422A, B, and E
We present deep images of dust continuum emission at 450, 800, and 850 micron
of the dark cloud LDN 1689N which harbors the low-mass young stellar objects
(YSOs) IRAS 16293-2422A and B (I16293A and I16293B) and the cold prestellar
object I16293E. Toward the positions of I16293A and E we also obtained spectra
of CO-isotopomers and deep submillimeter observations of chemically related
molecules with high critical densities. To I16293A we report the detection of
the HDO 1_01 - 0_00 and H2O 1_10 - 1_01 ground-state transitions as broad
self-reversed emission profiles with narrow absorption, and a tentative
detection of H2D+ 1_10 - 1_11. To I16293E we detect weak emission of
subthermally excited HDO 1_01 - 0_00. Based on this set of submillimeter
continuum and line data we model the envelopes around I16293A and E. The
density and velocity structure of I16293A is fit by an inside-out collapse
model, yielding a sound speed of a=0.7 km/s, an age of t=(0.6--2.5)e4 yr, and a
mass of 6.1 Msun. The density in the envelope of I16293E is fit by a radial
power law with index -1.0+/-0.2, a mass of 4.4 Msun, and a constant temperature
of 16K. These respective models are used to study the chemistry of the
envelopes of these pre- and protostellar objects.
The [HDO]/[H2O] abundance ratio in the warm inner envelope of I16293A of a
few times 1e-4 is comparable to that measured in comets. This supports the idea
that the [HDO]/[H2O] ratio is determined in the cold prestellar core phase and
conserved throughout the formation process of low-mass stars and planets.Comment: 61 pages, 17 figures. Accepted for publication in ApJ. To get Fig.
13: send email to [email protected]
The Electron Capture Ho Experiment ECHo: an overview
The determination of the absolute scale of the neutrino masses is one of the
most challenging present questions in particle physics. The most stringent
limit, eV, was achieved for the electron
anti-neutrino mass \cite{numass}. Different approaches are followed to achieve
a sensitivity on neutrino masses in the sub-eV range. Among them, experiments
exploring the beta decay or electron capture of suitable nuclides can provide
information on the electron neutrino mass value. We present the Electron
Capture Ho experiment ECHo, which aims to investigate the electron
neutrino mass in the sub-eV range by means of the analysis of the
calorimetrically measured energy spectrum following electron capture of
Ho. A high precision and high statistics spectrum will be measured with
arrays of metallic magnetic calorimeters. We discuss some of the essential
aspects of ECHo to reach the proposed sensitivity: detector optimization and
performance, multiplexed readout, Ho source production and
purification, as well as a precise theoretical and experimental
parameterization of the calorimetric EC spectrum including in particular the
value of . We present preliminary results obtained with a
first prototype of single channel detectors as well as a first 64-pixel chip
with integrated micro-wave SQUID multiplexer, which will already allow to
investigate in the eV range.Comment: Contribution to the LTD15 Conference Proceeding
Quantum point contact on graphite surface
The conductance through a quantum point contact created by a sharp and hard
metal tip on the graphite surface has features which to our knowledge have not
been encountered so far in metal contacts or in nanowires. In this paper we
first investigate these features which emerge from the strongly directional
bonding and electronic structure of graphite, and provide a theoretical
understanding for the electronic conduction through quantum point contacts. Our
study involves the molecular-dynamics simulations to reveal the variation of
interlayer distances and atomic structure at the proximity of the contact that
evolves by the tip pressing toward the surface. The effects of the elastic
deformation on the electronic structure, state density at the Fermi level, and
crystal potential are analyzed by performing self-consistent-field
pseudopotential calculations within the local-density approximation. It is
found that the metallicity of graphite increases under the uniaxial compressive
strain perpendicular to the basal plane. The quantum point contact is modeled
by a constriction with a realistic potential. The conductance is calculated by
representing the current transporting states in Laue representation, and the
variation of conductance with the evolution of contact is explained by taking
the characteristic features of graphite into account. It is shown that the
sequential puncturing of the layers characterizes the conductance.Comment: LaTeX, 11 pages, 9 figures (included), to be published in Phys. Rev.
B, tentatively scheduled for 15 September 1998 (Volume 58, Number 12
The IceCube Neutrino Observatory - Contributions to ICRC 2015 Part II: Atmospheric and Astrophysical Diffuse Neutrino Searches of All Flavors
Papers on atmospheric and astrophysical diffuse neutrino searches of all
flavors submitted to the 34th International Cosmic Ray Conference (ICRC 2015,
The Hague) by the IceCube Collaboration.Comment: 66 pages, 36 figures, Papers submitted to the 34th International
Cosmic Ray Conference, The Hague 2015, v2 has a corrected author lis
Improved limits on dark matter annihilation in the Sun with the 79-string IceCube detector and implications for supersymmetry
We present an improved event-level likelihood formalism for including
neutrino telescope data in global fits to new physics. We derive limits on
spin-dependent dark matter-proton scattering by employing the new formalism in
a re-analysis of data from the 79-string IceCube search for dark matter
annihilation in the Sun, including explicit energy information for each event.
The new analysis excludes a number of models in the weak-scale minimal
supersymmetric standard model (MSSM) for the first time. This work is
accompanied by the public release of the 79-string IceCube data, as well as an
associated computer code for applying the new likelihood to arbitrary dark
matter models.Comment: 24 pages, 8 figs, 1 table. Contact authors: Pat Scott & Matthias
Danninger. Likelihood tool available at http://nulike.hepforge.org. v2: small
updates to address JCAP referee repor
- …