10,838 research outputs found
Informative and misinformative interactions in a school of fish
It is generally accepted that, when moving in groups, animals process
information to coordinate their motion. Recent studies have begun to apply
rigorous methods based on Information Theory to quantify such distributed
computation. Following this perspective, we use transfer entropy to quantify
dynamic information flows locally in space and time across a school of fish
during directional changes around a circular tank, i.e. U-turns. This analysis
reveals peaks in information flows during collective U-turns and identifies two
different flows: an informative flow (positive transfer entropy) based on fish
that have already turned about fish that are turning, and a misinformative flow
(negative transfer entropy) based on fish that have not turned yet about fish
that are turning. We also reveal that the information flows are related to
relative position and alignment between fish, and identify spatial patterns of
information and misinformation cascades. This study offers several
methodological contributions and we expect further application of these
methodologies to reveal intricacies of self-organisation in other animal groups
and active matter in general
Some Phenomenology of Intersecting D-Brane Models
We present some phenomenology of a new class of intersecting D-brane models.
Soft SUSY breaking terms for these models are calculated in the u - moduli
dominant SUSY breaking approach (in type IIA). In this case, the dependence of
the soft terms on the Yukawas and Wilson lines drops out. These soft terms have
a different pattern compared to the usual heterotic string models.
Phenomenological implications for dark matter are discussed.Comment: 29 pages, 1 figure, References adde
A fast preemptive scheduling algorithm with release times and inclusive processing set restrictions
AbstractWe consider the problem of preemptively scheduling n independent jobs on m parallel machines so as to minimize the makespan. Each job Jj has a release time rj and it can only be processed on a subset of machines Mj. The machines are linearly ordered. Each job Jj has a machine index aj such that Mj={Maj,Maj+1,…,Mm}. We first show that there is no 1-competitive online algorithm for this problem. We then give an offline algorithm with a running time of O(nklogP+mnk2+m3k), where k is the number of distinct release times and P is the total processing time of all jobs
Valence band offset of InN/AlN heterojunctions measured by X-ray photoelectron spectroscopy
The valence band offset of wurtzite-InN/AlN (0001) heterojunctions is determined by x-ray photoelectron spectroscopy to be 1.52±0.17 eV. Together with the resulting conduction band offset of 4.0±0.2 eV, a type-I heterojunction forms between InN and AlN in the straddling arrangement
Chinese immigrant parents' vaccination decision making for children: A qualitative analysis
Background: While immunization coverage rates for childhood routine vaccines in Hong Kong are almost 100%, the uptake rates of optional vaccines remain suboptimal. Understanding parental decision-making for children's vaccination is important, particularly among minority groups who are most vulnerable and underserved. This study explored how a subsample of new immigrant mothers from mainland China, a rapidly-growing subpopulation in Hong Kong, made decisions on various childhood and adolescent vaccines for their offspring, and identified key influences affecting their decision making. Methods. Semi-structured in-depth interviews were conducted with 23 Chinese new immigrant mothers recruited by purposive sampling. All interviews were audio-taped, transcribed and analyzed using a Grounded Theory approach. Results: Participants' conversation revealed five underlying themes which influenced parents' vaccination decision-making: (1) Institutional factors, (2) Insufficient vaccination knowledge and advice, (3) Affective impacts on motivation, (4) Vaccination barriers, and (5) Social influences. The role of social norms appeared overwhelmingly salient influencing parents' vaccination decision making. Institutional factors shaped parent's perceptions of vaccination necessity. Fear of vaccine-targeted diseases was a key motivating factor for parents adopting vaccination. Insufficient knowledge about vaccines and targeted diseases, lack of advice from health professionals and, if provided, suspicions regarding the motivations for such advice were common issues. Vaccination cost was a major barrier for many new immigrant parents. Conclusions: Social norms play a key role influencing parental vaccination decision-making. Insight gained from this study will help inform healthcare providers in vaccination communication and policymakers in future vaccination programme. © 2014 Wang et al.; licensee BioMed Central Ltd.Link_to_subscribed_fulltex
The Compact X-ray Source 1E 1547.0-5408 and the Radio Shell G327.24-0.13: A New Proposed Association between a Candidate Magnetar and a Candidate Supernova Remnant
We present X-ray, infrared and radio observations of the field centered on
X-ray source 1E 1547.0-5408 in the Galactic Plane. A new Chandra observation of
this source shows it is unresolved at arc-second resolution, and a new XMM
observation shows that its X-ray spectrum is best described by an absorbed
power-law and blackbody model. A comparison of the X-ray flux observed from
this source between 1980 and 2006 reveals that its absorbed 0.5-10 keV X-ray
flux decreased from ~2x10^-12 ergs cm-2 s-1 to ~3x10^-13 ergs cm-2 during this
period. The most recent XMM observation allows us to put a 5 sigma confidence
upper limit of 14% for the 0.5-10 keV peak-to-peak pulsed fraction. A
near-infrared observation of this field shows a source with magnitude Ks =
15.9+/-0.2 near the position of 1E 1547.0-5408, but the implied X-ray to
infrared flux ratio indicates the infrared emission is from an unrelated field
source, allowing us to limit the IR magnitude of 1E 1547.0-5408 to >17.5.
Archival radio observations reveal that 1E 1547.0-5408 sits at the center of a
faint, small (4' diameter) radio shell, G327.24-0.13, which is possibly a
previously unidentified supernova remnant. The X-ray properties of 1E
1547.0-5408 suggest that this source is a magnetar - a young neutron star whose
X-ray emission is powered by the decay of its extremely strong magnetic field.
The spatial coincidence between this source and G327.24-0.13 suggests that 1E
1547.0-5408 is associated with a young supernova remnant, supporting a neutron
star interpretation. Additional observations are needed to confirm the nature
of both 1E 1547.0-5408 and G327.24-0.13, and to determine if these sources are
associated. If so, this pair will be an important addition to the small number
of known associations between magnetars and supernova remnants.Comment: 11 pages, 5 figures, ApJ accepte
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