17,898 research outputs found
An investigation of the relationship between rumination styles, hope, and suicide ideation through the lens of the integrated motivational-volitional model of suicidal behavior
To investigate the roles specific ruminative styles (brooding and reflection) and hope play in the Integrated Motivational-Volitional (IMV) model of suicidal behavior. Participants were students from a large U.S. state university who were selectively sampled for the experience of recent suicide ideation. Results of a bootstrapped moderated mediation model indicated that defeat had a direct effect on suicide ideation but not an indirect effect on suicide ideation through entrapment. Brooding, but not reflection, strengthened the relationship between defeat and entrapment. Hope weakened the relationship between entrapment and suicide ideation. Implications for the assessment and treatment of suicide risk and future research directions are discussed
The Construction of Spinor Fields on Manifolds with Smooth Degenerate Metrics
We examine some of the subtleties inherent in formulating a theory of spinors
on a manifold with a smooth degenerate metric. We concentrate on the case where
the metric is singular on a hypersurface that partitions the manifold into
Lorentzian and Euclidean domains. We introduce the notion of a complex spinor
fibration to make precise the meaning of continuity of a spinor field and give
an expression for the components of a local spinor connection that is valid in
the absence of a frame of local orthonormal vectors. These considerations
enable one to construct a Dirac equation for the discussion of the behavior of
spinors in the vicinity of the metric degeneracy. We conclude that the theory
contains more freedom than the spacetime Dirac theory and we discuss some of
the implications of this for the continuity of conserved currents.Comment: 24 pages, LaTeX (RevTeX 3.0, no figures), To appear in J. Math. Phy
Technical innovation changes standard radiographic protocols in veterinary medicine: is it necessary to obtain two dorsoproximal-palmarodistal oblique views of the equine foot when using computerised radiography systems?
Since the 1950s, veterinary practitioners have included two separate dorsoproximal–palmarodistal oblique (DPr–PaDiO) radiographs as part of a standard series of the equine foot. One image is obtained to visualise the distal phalanx and the other to visualise the navicular bone. However, rapid development of computed radiography and digital radiography and their post-processing capabilities could mean that this practice is no longer required. The aim of this study was to determine differences in perceived image quality between DPr–PaDiO radiographs that were acquired with a computerised radiography system with exposures, centring and collimation recommended for the navicular bone versus images acquired for the distal phalanx but were subsequently manipulated post-acquisition to highlight the navicular bone. Thirty images were presented to four clinicians for quality assessment and graded using a 1–3 scale (1=textbook quality, 2=diagnostic quality, 3=non-diagnostic image). No significant difference in diagnostic quality was found between the original navicular bone images and the manipulated distal phalanx images. This finding suggests that a single DPr–PaDiO image of the distal phalanx is sufficient for an equine foot radiographic series, with appropriate post-processing and manipulation. This change in protocol will result in reduced radiographic study time and decreased patient/personnel radiation exposure
Associations between EP-like lesions and pleuritis and post trimming carcass weights of finishing pigs in England
Herd health slaughter checks regularly identify enzootic pneumonia-like (EP-like) lesions and pleuritis. The aim of this paper is to determine the associations between these lesions and post-trimming carcass weight. Data were collected on the presence/absence and severity of EP-like lesions and presence/absence of pleuritis from pigs at the abattoir. Linear mixed models identified a significant association between an increase in EP-like lesion severity and a decrease in post-trimming carcass weight (P = 0.006) at the individual level. Each categorical increase in EP-like lesion severity (5 points step) was associated with a 0.37 kg reduction in post-trimming carcass weight. The presence of EP-like lesions in individual pigs, irrespective of severity (P = 0.034) and the presence of pleuritis (P = 0.038) were significantly associated with a reduction in post-trimming carcass weight of 1.26 kg and 1.25 kg respectively. The results confirm that the presence of these lesions at slaughter are associated with a significant decrease in production performance which can result in substantial economic implications for producers
Continental land cover classification using meteorological satellite data
The use of the National Oceanic and Atmospheric Administration's advanced very high resolution radiometer satellite data for classifying land cover and monitoring of vegetation dynamics over an extremely large area is demonstrated for the continent of Africa. Data from 17 imaging periods of 21 consecutive days each were composited by a technique sensitive to the in situ green-leaf biomass to provide cloud-free imagery for the whole continent. Virtually cloud-free images were obtainable even for equatorial areas. Seasonal variation in the density and extent of green leaf vegetation corresponded to the patterns of rainfall associated with the inter-tropical convergence zone. Regional variations, such as the 1982 drought in east Africa, were also observed. Integration of the weekly satellite data with respect to time produced a remotely sensed assessment of biological activity based upon density and duration of green-leaf biomass. Two of the 21-day composited data sets were used to produce a general land cover classification. The resultant land cover distributions correspond well to those of existing maps
A computer operated mass spectrometer system
Digital computer system for processing mass spectrometer output dat
Computer control of mass analyzers
Digital computer control of mass spectrometer
Delayed commutation in quantum computer networks
In the same way that classical computer networks connect and enhance the
capabilities of classical computers, quantum networks can combine the
advantages of quantum information and communications. We propose a
non-classical network element, a delayed commutation switch, that can solve the
problem of switching time in packet switching networks. With the help of some
local ancillary qubits and superdense codes we can route the information after
part of it has left the network node.Comment: 4 pages. 4 figures. Preliminar versio
Concentration of atomic hydrogen diffused into silicon in the temperature range 900–1300 °C
Boron-doped Czochralski silicon samples with [B]~1017 cm−3 have been heated at various temperatures in the range 800–1300 °C in an atmosphere of hydrogen and then quenched. The concentration of [H-B] pairs was measured by infrared localized vibrational mode spectroscopy. It was concluded that the solubility of atomic hydrogen is greater than [Hs] = 5.6 × 1018 exp( − 0.95 eV/kT)cm−3 at the temperatures investigated
Quantum-Dot Cellular Automata using Buried Dopants
The use of buried dopants to construct quantum-dot cellular automata is
investigated as an alternative to conventional electronic devices for
information transport and elementary computation. This provides a limit in
terms of miniaturisation for this type of system as each potential well is
formed by a single dopant atom. As an example, phosphorous donors in silicon
are found to have good energy level separation with incoherent switching times
of the order of microseconds. However, we also illustrate the possibility of
ultra-fast quantum coherent switching via adiabatic evolution. The switching
speeds are numerically calculated and found to be 10's of picoseconds or less
for a single cell. The effect of decoherence is also simulated in the form of a
dephasing process and limits are estimated for operation with finite dephasing.
The advantages and limitations of this scheme over the more conventional
quantum-dot based scheme are discussed. The use of a buried donor cellular
automata system is also discussed as an architecture for testing several
aspects of buried donor based quantum computing schemes.Comment: Minor changes in response to referees comments. Improved section on
scaling and added plot of incoherent switching time
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