6,811 research outputs found

### Strange and charged particle elliptic flow in Pb+Au collisions at 158 AGeV/c

We present $\Lambda$ and $\pi$ elliptic flow measurements from Pb+Au
collisions at the highest SPS energy. The data, collected by the CERES
experiment which covers $\eta=2.05,2.70$ with full azimuthal coverage and wide
$p_{T}$ sensitivity up to 3.5 GeV/c, can be used to test hydrodynamical models
and show sensitivity to the EoS. The value of $v_{2}$ as a function of
centrality and $p_{T}$ is presented. Values of $v_{2}$ observed by STAR at RHIC
are larger by about 1/3. Our measurements are compared to results from other
SPS experiments and to hydrodynamical calculations. Huge statistics allows for
a precise measurement of the differential pion elliptic flow.Comment: Proceeding for Quark Matter 2005, parallel talk, 4 pages, 7 figure

### Evolution of multi-gap superconductivity in the atomically thin limit: Strain-enhanced three-gap superconductivity in monolayer MgB$_2$

Starting from first principles, we show the formation and evolution of
superconducting gaps in MgB$_2$ at its ultrathin limit. Atomically thin MgB$_2$
is distinctly different from bulk MgB$_2$ in that surface states become
comparable in electronic density to the bulk-like $\sigma$- and $\pi$-bands.
Combining the ab initio electron-phonon coupling with the anisotropic
Eliashberg equations, we show that monolayer MgB$_2$ develops three distinct
superconducting gaps, on completely separate parts of the Fermi surface due to
the emergent surface contribution. These gaps hybridize nontrivially with every
extra monolayer added to the film, owing to the opening of additional coupling
channels. Furthermore, we reveal that the three-gap superconductivity in
monolayer MgB$_2$ is robust over the entire temperature range that stretches up
to a considerably high critical temperature of 20 K. The latter can be boosted
to $>$50 K under biaxial tensile strain of $\sim$ 4\%, which is an enhancement
stronger than in any other graphene-related superconductor known to date.Comment: To appear in Phys. Re

### Inelastic collisions of relativistic electrons with atomic targets assisted by a laser field

We consider inelastic collisions between relativistic electrons and atomic
targets assisted by a low-frequency laser field in the case when this field is
still much weaker than the typical internal fields in the target. Concentrating
on target transitions we show that they can be substantially affected by the
presence of the laser field. This may occur either via strong modifications in
the motion of the relativistic electrons caused by the electron-laser
interaction or via the Compton effect when the incident electrons convert laser
photon(s) into photons with frequencies equal to target transition frequencies.Comment: 4 pages, 2 figure

### Sharp oscillation criteria for fourth order sub-half-linear and super-half-linear differential equations

This paper is concerned with the oscillatory behavior of the fourth-order nonlinear differential equation
$\bigl(p(t)|x^{\prime\prime}|^{\alpha-1}\,x^{\prime\prime}\bigr)^{\prime\prime}
+q(t)|x|^{\beta-1}x=0\,,\tag{E}$
where $\alpha>0$, $\beta>0$ are constants and $p,q:[a,\infty)\to(0,\infty)$ are continuous functions satisfying conditions
$\int_a^{\infty}\left( \frac{t}{p(t)}\right)^{\frac{1}{\alpha}}\,dt<\infty,
\int_a^{\infty}\frac{t}{\left(p(t)\right)^{\frac{1}{\alpha}}}\,dt<\infty .$
We will establish necessary and sufficient condition for oscillation of all solutions of the sub-half-linear equation (E) (for $\beta\alpha$)

### Substrate induced proximity effect in superconducting niobium nanofilms

Structural and superconducting properties of high quality Niobium nanofilms
with different thicknesses are investigated on silicon oxide and sapphire
substrates. The role played by the different substrates and the superconducting
properties of the Nb films are discussed based on the defectivity of the films
and on the presence of an interfacial oxide layer between the Nb film and the
substrate. The X-ray absorption spectroscopy is employed to uncover the
structure of the interfacial layer. We show that this interfacial layer leads
to a strong proximity effect, specially in films deposited on a SiO$_2$
substrate, altering the superconducting properties of the Nb films. Our results
establish that the critical temperature is determined by an interplay between
quantum-size effects, due to the reduction of the Nb film thicknesses, and
proximity effects

### Increased risk of HIV and other drug-related harms associated with injecting in public places: national bio-behavioural survey of people who inject drugs

Background:
Whilst injecting drugs in public places is considered a proxy for high risk behaviour among people who inject drugs (PWID), studies quantifying its relationship with multiple drug-related harms are lacking and none have examined this in the context of an ongoing HIV outbreak (located in Glasgow, Scotland). We aimed to: 1) estimate the prevalence of public injecting in Scotland and associated risk factors; and 2) estimate the association between public injecting and HIV, current HCV, overdose, and skin and soft tissue infections (SSTI).
Methods:
Cross-sectional, bio-behavioural survey (including dried blood spot testing to determine HIV and HCV infection) of 1469 current PWID (injected in last 6 months) recruited by independent interviewers from 139 harm reduction services across Scotland during 2017â€“18. Primary outcomes were: injecting in a public place (yes/no); HIV infection; current HCV infection; self-reported overdose in the last year (yes/no) and SSTI the last year (yes/no). Multi-variable logistic regression was used to determine factors associated with public injecting and to estimate the association between public injecting and drug-related harms (HIV, current HCV, overdose and SSTI).
Results:
Prevalence of public injecting was 16% overall in Scotland and 47% in Glasgow city centre. Factors associated with increased odds of public injecting were: recruitment in Glasgow city centre (aOR=5.45, 95% CI 3.48â€“8.54, p<0.001), homelessness (aOR=3.68, 95% CI 2.61â€“5.19, p<0.001), high alcohol consumption (aOR=2.42, 95% CI 1.69â€“3.44, p<0.001), high injection frequency (â‰¥4 per day) (aOR=3.16, 95% CI 1.93â€“5.18, p<0.001) and cocaine injecting (aOR=1.46, 95% CI 1.00 to 2.13, p = 0.046). Odds were lower for those receiving opiate substitution therapy (OST) (aOR=0.37, 95% CI 0.24 to 0.56, p<0.001) and older age (per year increase) (aOR=0.97, 95% CI 0.95 to 0.99, p = 0.013). Public injecting was associated with an increased risk of HIV infection (aOR=2.11, 95% CI 1.13â€“3.92, p = 0.019), current HCV infection (aOR=1.49, 95% CI 1.01â€“2.19, p = 0.043), overdose (aOR=1.59, 95% CI 1.27â€“2.01, p<0.001) and SSTI (aOR=1.42, 95% CI 1.17â€“1.73, p<0.001).
Conclusions:
These findings highlight the need to address the additional harms observed among people who inject in public places and provide evidence to inform proposals in the UK and elsewhere to introduce facilities that offer safer drug consumption environments

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