35,264 research outputs found
Dynamics of coreless vortices and rotation-induced dissipation peak in superfluid films on rotating porous substrates
We analyze dynamics of 3D coreless vortices in superfluid films covering
porous substrates. The 3D vortex dynamics is derived from the 2D dynamics of
the film. The motion of a 3D vortex is a sequence of jumps between neighboring
substrate cells, which can be described, nevertheless, in terms of
quasi-continuous motion with average vortex velocity. The vortex velocity is
derived from the dissociation rate of vortex-antivortex pairs in a 2D film,
which was developed in the past on the basis of the Kosterlitz-Thouless theory.
The theory explains the rotation-induced dissipation peak in torsion-oscillator
experiments on He films on rotating porous substrates and can be used in
the analysis of other phenomena related to vortex motion in films on porous
substrates.Comment: 8 pages, 3 figures submitted to Phys. Rev.
Improvements in Cd stable isotope analysis achieved through use of liquid–liquid extraction to remove organic residues from Cd separates obtained by extraction chromatography
Organic compounds released from resins that are commonly employed for trace element separations are known to have a detrimental impact on the quality of isotopic analyses by MC-ICP-MS. A recent study highlighted that such effects can be particularly problematic for Cd stable isotope measurements (M. Gault-Ringold and C. H. Stirling, J. Anal. At. Spectrom., 2012, 27, 449–459). In this case, the final stage of sample purification commonly applies extraction chromatography with Eichrom TRU resin, which employs particles coated with octylphenyl-N,N-di-isobutyl carbamoylphosphine oxide (CMPO) dissolved in tri-n-butyl phosphate (TBP). During chromatography, it appears that some of these compounds are eluted alongside Cd and cannot be removed by evaporation due to their high boiling points. When aliquots of the zero-ε reference material were processed through the purification procedure, refluxed in concentrated HNO(3) and analyzed at minimum dilution (in 1 ml 0.1 M HNO(3)), they yielded Cd isotopic compositions (ε(114/110)Cd = 4.6 ± 3.4, 2SD, n = 4) that differed significantly from the expected value, despite the use of a double spike technique to correct for instrumental mass fractionation. This result was accompanied by a 35% reduction in instrumental sensitivity for Cd. With increasing dilution of the organic resin residue, both of these effects are reduced and they are insignificant when the eluted Cd is dissolved in ≥3 ml 0.1 M HNO(3). Our results, furthermore, indicate that the isotopic artefacts are most likely related to anomalous mass bias behavior. Previous studies have shown that perchloric acid can be effective at avoiding such effects (Gault-Ringold and Stirling, 2012; K. C. Crocket, M. Lambelet, T. van de Flierdt, M. Rehkämper and L. F. Robinson, Chem. Geol., 2014, 374–375, 128–140), presumably by oxidizing the resin-derived organics, but there are numerous disadvantages to its use. Here we show that liquid–liquid extraction with n-heptane removes the organic compounds, dramatically improving quality of the Cd isotope data for samples that are analyzed at or close to minimum dilution factors. This technique is quick, simple and may be of use prior to analysis of other isotope systems where similar resins are employed
Rotational CARS application to simultaneous and multiple-point temperature and concentration determination in a turbulent flow
Coherent anti-Stokes Raman scattering (CARS) from the pure rotational Raman lines of N2 is employed to measure the instantaneous (approximately 10 ns) rotational temperature of N2 gas at room temperature and below with good spatial resolution (0.2 x 0.2 x 3.0 cu mm). A broad bandwidth dye laser is used to obtain the entire rotational spectrum from a single laser pulse; the CARS signal is then dispersed by a spectrograph and recorded on an optical multichannel analyzer. A best fit temperature is found in several seconds with the aid of a computer for each experimental spectrum by a least squares comparison with calculated spectra. The model used to calculate the theoretical spectra incorporates the temperature and pressure dependence of the pressure-broadened rotational Raman lines, includes the nonresonant background susceptibility, and assumes that the pump laser has a finite linewidth. Temperatures are fit to experimental spectra recorded over the temperature range of 135 to 296 K, and over the pressure range of .13 to 15.3 atm
Extensions of C*-dynamical systems to systems with complete transfer operators
Starting from an arbitrary endomorphism of a unital C*-algebra
we construct a bigger C*-algebra and extend onto in such a way
that the extended endomorphism has a unital kernel and a hereditary
range, i.e. there exists a unique non-degenerate transfer operator for
, called the complete transfer operator. The pair is
universal with respect to a suitable notion of a covariant representation and
depends on a choice of an ideal in . The construction enables a natural
definition of the crossed product for arbitrary .Comment: Compressed and submitted version, 9 page
“I Didn’t Feel I Was A Victim”: A Phenomenological Analysis of the Experiences of Male-on-male Survivors of Rape and Sexual Abuse
Research on men’s experiences of sexual victimization is limited and largely outdated. The present study seeks to remedy this issue by qualitatively examining the accounts of nine male-on-male survivors of rape and sexual abuse in the UK. It examines survivors’ experiences of psychological distress post-incident, the influence and manifestation of male rape myths, challenges in self-recognition and disclosure, and barriers to accessing therapeutic support and reporting to the Criminal Justice System (CJS). Participants took part in one-to-one, semi-structured video interviews, and an interpretative phenomenological analysis (IPA) was utilized to identify four superordinate themes of participants’ experiences: i) gendered narratives, ii) coping with the abuse, iii) masculinity, and iv) reporting to the police. These themes emphasized the stigma and hostility repeatedly encountered by survivors after their victimization. Participants provided an account of short and long-term psychological issues following the abuse, emphasizing the role of self-perceptions of masculinity in the development of unhealthy coping mechanisms. Findings also highlighted the prevalence of prejudice and rape mythology that characterized negative encounters within the public, voluntary agencies, and the CJS. Results are discussed in relation to current service provision in the UK, recommendations for future research, and avenues for improvements across multiple vital entry points
The connection between metallicity and metal-line kinematics in (sub-)damped Lyman-alpha systems
A correlation between the metallicity, [M/H], and rest-frame MgII equivalent
width, EW, is found from 49 DLAs and strong sub-DLAs drawn from the literature
over the redshift range 0.2<z_abs<2.6. The correlation is significant at 4.2
sigma and improves to 4.7 sigma when the mild evolution of [M/H] with redshift
is taken into account. Even when including only the 26 DLAs (i.e. excluding
sub-DLAs) which have Zn metallicities and EW>0.7A, the correlation remains at
>3 sigma significance. Since the MgII2796 transition is predominantly saturated
in DLAs (which always have EW greater than 0.3A), EW is far more sensitive to
the kinematic spread of the metal velocity components across the absorption
profile than it is to [M/H]. Thus, the observed [M/H]--EW correlation points to
a strong link between the absorber metallicity and the mechanism for producing
and dispersing the velocity components. We also note that approximately half of
the 13 known molecular hydrogen absorbers have very high EW and very broad
velocity structures which show characteristics usually associated with
outflows. Follow-up ultraviolet- and blue-sensitive high-resolution spectra of
high-EW systems, initially identified in low-resolution spectra, may therefore
yield a large number of new H_2 discoveries.Comment: 9 pages, 2 figures (3 EPS files). Accepted by MNRA
Doing Well and Happy About It? Explaining Variance in Entrepreneurs’ Stated Satisfaction with Performance
The importance of performance measurement is largely undisputed. There is debate, however, regarding the equivalency of objective and subjective performance measures. This debate has not considered a frequently used subjective measure, satisfaction with performance, to be an important measure independent of its equivalency with objective measures. Using a sample of 368 manufacturing firms, this study found that objective measures explained only a modest amount of variance in satisfaction with performance and that other variables added significantly to the explained variance.These factors included perceived environmental hostility, vulnerability, perceived competitive advantage, and commitment
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