4,375 research outputs found
Transition region features observed with Hinode/EIS
Two types of active region feature prominent at transition region
temperatures are identified in Hinode/EIS data of AR 10938 taken on 2007
January 20. The footpoints of 1 MK TRACE loops are shown to emit strongly in
emission lines formed at log T=5.4-5.8, allowing the temperature increase along
the footpoints to be clearly seen. A density diagnostic of Mg VII yields the
density in the footpoints, with one loop showing a decrease from 3x10^9 cm^-3
at the base to 1.5x10^9 cm^-3 at a projected height of 20 Mm. The second
feature is a compact active region transition region brightening which is
particularly intense in O V emission (log T=5.4) but also has a signature at
temperatures up to log T=6.3. The Mg VII diagnostic gives a density of 4x10^10
cm^-3, and emission lines of Mg VI and Mg VII show line profiles broadened by
50 km/s and wings extending beyond 200 km/s. Continuum emission in the short
wavelength band is also found to be enhanced, and is suggested to be free-bound
emission from recombination onto He^+.Comment: 11 pages, 9 figures, submitted to PASJ Hinode first results issu
Incommensurate Charge and Spin Fluctuations in d-wave Superconductors
We show analytic results for the irreducible charge and spin
susceptibilities, , where is the momentum
transfer between the nodes in d-wave superconductors. Using the BCS theory and
a circular Fermi surface, we find that the singular behavior of the irreducible
charge susceptibility leads to the dynamic incommensurate charge collective
modes. The peaks in the charge structure factor occur at a set of wave vectors
which form an ellipse around and in
momentum space with momentum dependent spectral weight. It is also found that,
due to the non-singular irreducible spin susceptibility, an extremely strong
interaction via random phase approximation is required to support the magnetic
peaks near . Under certain conditions, the peaks in the magnetic
structure factor occur near and .Comment: 5 pages, 3 figure
The transformation of the business angel market: empirical evidence and research implications
Business angel investing – a key source of finance for entrepreneurial businesses – is rapidly evolving from a fragmented and largely anonymous activity dominated by individuals investing on their own to one that is increasingly characterised by groups of investors investing together through managed angel groups. The implications of this change have been largely ignored by scholars. The paper examines the investment activity and operation of angel groups in Scotland to highlight the implications of this change for the nature of angel investing. It goes on to argue that this transformation challenges both the ongoing relevance of prior research on business angels and current methodological practices, and raises a set of new research questions
Sound Propagation in Nematic Fermi Liquid
We study the longitudinal sound propagation in the electronic nematic Fermi
liquid where the Fermi surface is distorted due to the spontaneously broken
rotational symmetry. The behavior of the sound wave in the nematic ordered
state is dramatically different from that in the isotropic Fermi liquid. The
collective modes associated with the fluctuations of the Fermi surface
distortion in the nematic Fermi liquid leads to the strong and anisotropic
damping of the sound wave. The relevance of the nematic Fermi liquid in doped
Mott insulator is discussed.Comment: 4 pages, no figur
Potential impact of reactive vaccination in controlling cholera outbreaks: An exploratory analysis using a Zimbabwean experience
Background. To contain ongoing cholera outbreaks, the World Health Organization has suggested that reactive vaccination should be considered in addition to its previous control measures.
Objectives. To explore the potential impact of a hypothetical reactive oral cholera vaccination using the example of the recent large-scale cholera outbreak in Zimbabwe.
Methods. This was a retrospective cost-effectiveness analysis calculating the health and economic burden of the cholera outbreak in Zimbabwe with and without reactive vaccination. The primary outcome measure was incremental cost per disability-adjusted life year (DALY) averted.
Results. Under the base-case assumptions (assuming 50% coverage among individuals aged ≥2 years), reactive vaccination could have averted 1 320 deaths and 23 650 DALYs. Considering herd immunity, the corresponding values would have been 2 920 deaths and 52 360 DALYs averted. The total vaccination costs would have been ~21 million, respectively, with per-dose vaccine price of US1. The incremental costs per DALY averted of reactive vaccination were 370, respectively, for vaccine price set at 1. Assuming herd immunity, the corresponding cost was 5, and the programme was cost-saving with a vaccine price of $1. Results were most sensitive to case-fatality rate, per-dose vaccine price, and the size of the outbreak.
Conclusions. Reactive vaccination has the potential to be a cost-effective measure to contain cholera outbreaks in countries at high risk. However, the feasibility of implementation should be further evaluated, and caution is warranted in extrapolating the findings to different settings in the absence of other in-depth studies
Adsorption hysteresis and capillary condensation in disordered porous solids: a density functional study
We present a theoretical study of capillary condensation of fluids adsorbed
in mesoporous disordered media. Combining mean-field density functional theory
with a coarse-grained description in terms of a lattice-gas model allows us to
investigate both the out-of-equilibrium (hysteresis) and the equilibrium
behavior. We show that the main features of capillary condensation in
disordered solids result from the appearance of a complex free-energy landscape
with a large number of metastable states. We detail the numerical procedures
for finding these states, and the presence or absence of transitions in the
thermodynamic limit is determined by careful finite-size studies.Comment: 30 pages, 18 figures. To appear in J. Phys.: Condens. Matte
Who will use pre-exposure prophylaxis (PrEP) and why?: Understanding PrEP awareness and acceptability amongst men who have sex with men in the UK – a mixed methods study
Background:
Recent clinical trials suggest that pre-exposure prophylaxis (PrEP) may reduce HIV transmission by up to 86% for men who have sex with men (MSM), whilst relatively high levels of PrEP acceptability have been reported to date. This study examines PrEP awareness amongst sub-groups of MSM communities and acceptability amongst MSM in a low prevalence region (Scotland, UK), using a mixed methods design.
Methods:
Quantitative surveys of n = 690 MSM recruited online via social and sociosexual media were analysed using descriptive statistics and multivariate logistic regression. In addition, n = 10 in-depth qualitative interviews with MSM were analysed thematically.
Results:
Under one third (29.7%) of MSM had heard of PrEP, with awareness related to living in large cities, degree level education, commercial gay scene use and reporting an HIV test in the last year. Just under half of participants (47.8%) were likely to use PrEP if it were available but there was no relationship between PrEP acceptability and previous PrEP awareness. Younger men (18–25 years) and those who report higher risk UAI were significantly more likely to say they would use PrEP. Qualitative data described specific PrEP scenarios, illustrating how risk, patterns of sexual practice and social relationships could affect motivation for and nature of PrEP use.
Conclusion:
These findings suggest substantial interest PrEP amongst MSM reporting HIV risk behaviours in Scotland. Given the Proud results, there is a strong case to investigate PrEP implementation within the UK. However, it appears that disparities in awareness have already emerged along traditional indicators of inequality. Our research identifies the need for comprehensive support when PrEP is introduced, including a key online component, to ensure equity of awareness across diverse MSM communities (e.g. by geography, education, gay scene use and HIV proximity), as well as to responding to the diverse informational and sexual health needs of all MSM communities
Spectropolarimetry of the 3.4 micron absorption feature in NGC 1068
In order to test the silicate-core/organic-mantle model of galactic
interstellar dust, we have performed spectropolarimetry of the 3.4 micron C-H
bond stretch that is characteristic of aliphatic hydrocarbons, using the
nucleus of the Seyfert 2 galaxy, NGC 1068, as a bright, dusty background
source. Polarization calculations show that, if the grains in NGC 1068 had the
properties assigned by the core-mantle model to dust in the galactic diffuse
ISM, they would cause a detectable rise in polarization over the 3.4 micron
feature. No such increase is observed. We discuss modifications to the basic
core-mantle model, such as changes in grain size or the existence of additional
non-hydrocarbon aligned grain populations, which could better fit the
observational evidence. However, we emphasize that the absence of polarization
over the 3.4 micron band in NGC 1068 - and, indeed, in every line of sight
examined to date - can be readily explained by a population of small, unaligned
carbonaceous grains with no physical connection to the silicates.Comment: ApJ, accepte
EUV emission lines and diagnostics observed with Hinode/EIS
Quiet Sun and active region spectra from the Hinode/EIS instrument are
presented, and the strongest lines from different temperature regions
discussed. A list of emission lines recommended to be included in EIS
observation studies is presented based on analysis of blending and diagnostic
potential using the CHIANTI atomic database. In addition we identify the most
useful density diagnostics from the ions covered by EIS.Comment: 14 pages, 3 figures, submitted to PASJ Hinode first results issu
Cognitive Information Processing
Contains reports on six research projects.National Institutes of Health (Grant 1 PO1 GM-14940-01)National Institutes of Health (Grant 1 PO1 GM-15006-01)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E)Project MAC, an M. I. T. research programAdvanced Research Projects Agency, Department of Defense, under Office of Naval Research Contract Nonr-4102-(01
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