4,658 research outputs found
A critical Mach number for electron injection in collisionless shocks
Electron acceleration in collisionless shocks with arbitrary magnetic field
orientations is discussed. It is shown that the injection of thermal electrons
into diffusive shock acceleration process is achieved by an electron beam with
a loss-cone in velocity space that is reflected back upstream from the shock
through shock drift acceleration mechanism. The electron beam is able to excite
whistler waves which can scatter the energetic electrons themselves when the
Alfven Mach number of the shock is sufficiently high. A critical Mach number
for the electron injection is obtained as a function of upstream parameters.
The application to supernova remnant shocks is discussed.Comment: 4 pages, 2 figure, accepted for publication in Physical Review
Letter
Modes of the Sakai-Sugimoto soliton
The instanton in the Sakai-Sugimoto model corresponds to the Skyrmion on the
holographic boundary - which is asymptotically flat - and is fundamentally
different from the flat Minkowski space Yang-Mills instanton. We use the
Atiyah-Patodi-Singer index theorem and a series of transformations to show that
there are 6k zeromodes - or moduli - in the limit of infinite 't Hooft coupling
of the Sakai-Sugimoto model. The implications for the low-energy baryons - the
Skyrmions - on the holographic boundary, is a scale separation between 2k
"heavy" massive modes and 6k-9 "light" massive modes for k>1; the 9 global
transformations that correspond to translations, rotations and isorotations
remain as zeromodes. For k=1 there are 2 "heavy" modes and 6 zeromodes due to
degeneracy between rotations and isorotations.Comment: LaTeX: 14 pages, 3 figure
Partograph utilization and associated factors among obstetric care providers in North Shoa Zone, Central Ethiopia: a cross sectional study
Background: Globally, prolonged and obstructed labor contributed to 8% of maternal deaths which can be reduced by proper utilization of partograph during labor.Methods: An Institution based cross-sectional study was conducted in June, 2013 on 403 obstetric care providers. A pre-tested and structured questionnaire was used to collect data. Data was entered to EpiInfo version 3.5.1 statistical package and exported to SPSS version 20.0 for further analysis. Logistic regression analyses were used to see the association of different variables.Results: Out of 403 obstetric care providers, 40.2% utilized partograph during labor.Those who were midwives by profession were about 8 times more likely to have a consistent utilization of the partograph than general practitioners (AOR=8. 13, 95% CI: 2.67, 24.78). Similarly, getting on job training (AOR=2. 86, 95% CI: 1.69, 4.86), being knowledgeable on partograph (AOR=3. 79, 95% CI: 2.05, 7.03) and having favorable attitude towards partograph (AOR=2. 35, 95% CI: 1.14, 4.87) were positively associated with partograph utilization.Conclusion: Partograph utilization in labor monitoring was found to be low. Being a midwife by profession, on job training, knowledge and attitude of obstetric care providers were factors affecting partograph utilization. Providing on job training for providers would improve partograph utilization.Keywords: Ethiopia, obstetric care providers, partograp
Electronic structures of CeRu ( = Si, Ge) in the paramagnetic phase studied by soft X-ray ARPES and hard X-ray photoelectron spectroscopy
Soft and hard X-ray photoelectron spectroscopy (PES) has been performed for
one of the heavy fermion system CeRuSi and a -localized ferromagnet
CeRuGe in the paramagnetic phase. The three-dimensional band structures
and Fermi surface (FS) shapes of CeRuSi have been determined by soft
X-ray -dependent angle resolved photoelectron spectroscopy (ARPES). The
differences in the Fermi surface topology and the non- electronic
structures between CeRuSi and CeRuGe are qualitatively
explained by the band-structure calculation for both itinerant and
localized models, respectively. The Ce valences in CeRu ( = Si, Ge)
at 20 K are quantitatively estimated by the single impurity Anderson model
calculation, where the Ce 3d hard X-ray core-level PES and Ce 3d X-ray
absorption spectra have shown stronger hybridization and signature for the
partial contribution to the conduction electrons in CeRuSi.Comment: 8figure
Motion of glossy objects does not promote separation of lighting and surface colour
The surface properties of an object, such as texture, glossiness or colour, provide important cues to its identity. However, the actual visual stimulus received by the eye is determined by both the properties of the object and the illumination. We tested whether operational colour constancy for glossy objects (the ability to distinguish changes in spectral reflectance of the object, from changes in the spectrum of the illumination) was affected by rotational motion of either the object or the light source. The different chromatic and geometric properties of the specular and diffuse reflections provide the basis for this discrimination, and we systematically varied specularity to control the available information. Observers viewed animations of isolated objects undergoing either lighting or surface-based spectral transformations accompanied by motion. By varying the axis of rotation, and surface patterning or geometry, we manipulated: (i) motion-related information about the scene, (ii) relative motion between the surface patterning and the specular reflection of the lighting, and (iii) image disruption caused by this motion. Despite large individual differences in performance with static stimuli, motion manipulations neither improved nor degraded performance. As motion significantly disrupts frameby-frame low-level image statistics, we infer that operational constancy depends on a high-level scene interpretation, which is maintained in all condition
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Nature and Community Cohesion
Individuals may be losing touch with nature as their contact with it decreases worldwide. While the consequences for people’s personal well-being outcomes are becoming well documented, there is almost no research examining the social correlates of contact with nature. This paper used a large nationally representative sample to link objective (% greenspace) and subjective measurements of contact with nature, community cohesion, and local crime incidence. The perceived quality, views, and amount of time spent in nature were linked to more community cohesion, and in turn the perception of cohesive communities enhances individual well-being outcomes and contributions back to society through higher workplace productivity and environmentally responsible behaviors. Findings also indicated that local nature was linked to lower crime both directly and indirectly through its effects on community cohesion.This research was funded in part by the ESRC (project number RES-064-27-0019).This is the author accepted manuscript. The final version is available from Oxford University Press via http://dx.doi.org/10.1093/biosci/biv15
High-dose paroxetine treatment for an adolescent with obsessive-compulsive disorder comorbid with Asperger's disorder
The definitive version is available at www.blackwell-synergy.comArticlePSYCHIATRY AND CLINICAL NEUROSCIENCES. 63(2):251 (2009)journal articl
A Difference Version of Nori's Theorem
We consider (Frobenius) difference equations over (F_q(s,t), phi) where phi
fixes t and acts on F_q(s) as the Frobenius endomorphism. We prove that every
semisimple, simply-connected linear algebraic group G defined over F_q can be
realized as a difference Galois group over F_{q^i}(s,t) for some i in N. The
proof uses upper and lower bounds on the Galois group scheme of a Frobenius
difference equation that are developed in this paper. The result can be seen as
a difference analogue of Nori's Theorem which states that G(F_q) occurs as
(finite) Galois group over F_q(s).Comment: 29 page
Conservation practice could benefit from routine testing and publication of management outcomes
Effective conservation requires a step change in the way practitioners can contribute to science and
can have access to research outputs. The journal Conservation Evidence was established in 2004 to
help practitioners surmount several obstacles they face when attempting to document the effects of
their conservation actions scientifically. It is easily and freely accessible online. It is free to publish in
and it enables global communication of the effects of practical trials and experiments, which are
virtually impossible to get published in most scientific journals. The driving force behind
Conservation Evidence is the need to generate and share scientific information about the effects of
interventions
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