1,746 research outputs found
A superconducting absolute spin valve
A superconductor with a spin-split excitation spectrum behaves as an ideal
ferromagnetic spin-injector in a tunneling junction. It was theoretical
predicted that the combination of two such spin-split superconductors with
independently tunable magnetizations, may be used as an ideal
spin-valve. Here we report on the first switchable superconducting spin-valve
based on two EuS/Al bilayers coupled through an aluminum oxide tunnel barrier.
The spin-valve shows a relative resistance change between the parallel and
antiparallel configuration of the EuS layers up to 900% that demonstrates a
highly spin-polarized currents through the junction. Our device may be pivotal
for realization of thermoelectric radiation detectors, logical element for a
memory cell in cryogenics superconductor-based computers and superconducting
spintronics in general.Comment: 6 pages, 4 color figures, 1 tabl
Revealing the magnetic proximity effect in EuS/Al bilayers through superconducting tunneling spectroscopy
A ferromagnetic insulator attached to a superconductor is known to induce an
exchange splitting of the Bardeen-Cooper-Schrieffer (BCS) singularity by a
magnitude proportional to the magnetization, and penetrating into the
superconductor to a depth comparable with the superconducting coherence length.
We study this long-range magnetic proximity effect in EuS/Al bilayers and find
that the exchange splitting of the BCS peaks is present already in the
unpolarized state of the ferromagnetic insulator (EuS), and is being further
enhanced when magnetizing the sample by a magnetic field. The measurement data
taken at the lowest temperatures feature a high contrast which has allowed us
to relate the line shape of the split BCS conductance peaks to the
characteristic magnetic domain structure of the EuS layer in the unpolarized
state. These results pave the way to engineering triplet superconducting
correlations at domain walls in EuS/Al bilayers. Furthermore, the hard gap and
clear splitting observed in our tunneling spectroscopy measurements indicate
that EuS/Al bilayers are excellent candidates for substituting strong magnetic
fields in experiments studying Majorana bound states.Comment: 9 pages, 4 color figure
Female Adolescentsâ Attitude towards Sexually Risky Behaviors
This cross-sectional survey examines the association between attitudes and female adolescentsâ sexually risky behaviors. A sample of 159 subjects, aged 14 â 20 from three high schools in West Virginia participated in the study. The results indicate that 60.3% (n = 96) reported having had sexual intercourse and, of this sexually active group, 60.4% (n = 58) stated that they had sex the first time at age 15 or younger. Fifty-five percent (n = 88) reported at least one of the following behaviors: (1) sexual initiation at age 15 or younger, (2) frequent sexual intercourse last month, (3) multiple sex partners, (4) unprotected sex during last sex, and (5) had sex with drug or alcohol. Multiple regression analysis indicates that those participants who favor premarital sex were more likely to engage in sexually risky behaviors. The items of âfavoring premarital sexâ and âliving arrangementsâ were the only two items that were independently found to be related to the sexually risky behaviors. Female adolescents who lived with both parents were less likely to engage in sexually risky behaviors
Optical supercavitation in soft-matter
We investigate theoretically, numerically and experimentally nonlinear
optical waves in an absorbing out-of-equilibrium colloidal material at the
gelification transition. At sufficiently high optical intensity, absorption is
frustrated and light propagates into the medium. The process is mediated by the
formation of a matter-shock wave due to optically induced thermodiffusion, and
largely resembles the mechanism of hydrodynamical supercavitation, as it is
accompanied by a dynamic phase-transition region between the beam and the
absorbing material.Comment: 4 pages, 5 figures, revised version: corrected typos and reference
Kill rate as a tool in efficiency evaluation of Neoseiulus californicus (Acari: Phytoseiidae) mass reared on factitious food
The predatory mites of the Phytoseiidae family are crucial biological control agents widely utilized in biological pest management targeting phytophagous mites and insects. Key factors in these control strategies are that phytoseiids must be able to find their main target prey and to maintain high populations and efficacy. To reduce expenses and time-consuming production methods of mass rearing of phytoseiids, pollen and other factitious (i.e., non-natural/nontarget) hosts need to be present as an alternative food for predatory mite populations. The mass-rearing possibilities of these predators on alternative food sources, such as astigmatid mites (i.e., house and stored mites) and pollen, must be evaluated not only by the cost of rearing settings but on the basis of their efficiency maintenance in killing prey. The pest kill rate (km) is the average daily lifetime killing of the pest by the natural enemy under consideration and can represent a useful indicator for phytoseiids efficacy to rank them as BCAs on the basis of their effective killing/predation on target prey. In this study, we evidenced that 2 astigmatid mites, Glycyphagus domesticus (De Geer) and Lepidoglyphus destructor (Schrank), and Quercus ilex L. pollen can be successfully adopted as substitute food sources for mass rearing of the phytoseiid Neoseiulus californicus (MgGregor); then, we determined that these populations of BCAs maintained a consistent km at new/first impact on the main target pest, Tetranychus urticae Koch
Elasto-viscoplastic modeling of subsidence above gas fields in the Adriatic Sea
Abstract. From the analysis of GPS monitoring data collected above gas
fields in the Adriatic Sea, in a few cases subsidence responses have been
observed not to directly correlate with the production trend. Such behavior,
already described in the literature, may be due to several physical
phenomena, ranging from simple delayed aquifer depletion to a much more
complex time-dependent mechanical response of subsurface geomaterials to
fluid withdrawal. In order to accurately reproduce it and therefore to be
able to provide reliable forecasts, in the last years Eni has enriched its
3D finite element geomechanical modeling workflow by adopting an advanced
constitutive model (Vermeer and Neher, 1999), which also considers the
viscous component of the deformation. While the numerical implementation of
such methodology has already been validated at laboratory scale and tested
on synthetic hydrocarbon fields, the work herein presents its first
application to a real gas field in the Adriatic Sea where the phenomenon has
been observed. The results show that the model is capable to reproduce very
accurately both GPS data and other available measurements. It is worth
remarking that initial runs, characterized by the use of model parameter
values directly obtained from the interpretation of mechanical laboratory
tests, already provided very good results and only minor tuning operations
have been required to perfect the model outcomes. Ongoing R&D projects
are focused on a regional scale characterization of the Adriatic Sea basin
in the framework of the Vermeer and Neher model approach
IMPACT OF AGRICULTURAL MANAGEMENT ON COMMUNITIES OF ORIBATIDA, GAMASINA AND COLLEMBOLA IN ITALIAN AND FRENCH VINEYARDS
Quantitative and qualitative analyses among the soil microarthropods can be used in biomonitoring as tools in multi-disciplinary approach to characterize soil quality. Three groups of microarthropods - Collembola and Oribatida as detrivores and Gamasina as predators - were selected to evaluate the impact of different management treatments adopted to recover degraded soil in organic. Differences in arthropod populations between French and Italian sites were registered. In Italy, after two years of recovering treatments, an increase of the abundances of all groups, particularly detritivores in degraded plots, was observed. The population of gamasids increased, in all sites, only in non degraded plots. Soil invertebrates of similar trophic groups, like collembolans and oribatids, seem to differently respond to treatments: the collembolans were more affected by some agronomic practices enhancing soil fertility
Testing the performance of an innovative markerless technique for quantitative and qualitative gait analysis
Gait abnormalities such as high stride and step frequency/cadence (SF-stride/second, CAD-step/second), stride variability (SV) and low harmony may increase the risk of injuries and be a sentinel of medical conditions. This research aims to present a new markerless video-based technology for quantitative and qualitative gait analysis. 86 healthy individuals (mead age 32 years) performed a 90 s test on treadmill at self-selected walking speed. We measured SF and CAD by a photoelectric sensors system; then, we calculated average \ub1 standard deviation (SD) and within-subject coefficient of variation (CV) of SF as an index of SV. We also recorded a 60 fps video of the patient. With a custom-designed web-based video analysis software, we performed a spectral analysis of the brightness over time for each pixel of the image, that reinstituted the frequency contents of the videos. The two main frequency contents (F1 and F2) from this analysis should reflect the forcing/dominant variables, i.e., SF and CAD. Then, a harmony index (HI) was calculated, that should reflect the proportion of the pixels of the image that move consistently with F1 or its supraharmonics. The higher the HI value, the less variable the gait. The correspondence SF-F1 and CAD-F2 was evaluated with both paired t-Test and correlation and the relationship between SV and HI with correlation. SF and CAD were not significantly different from and highly correlated with F1 (0.893 \ub1 0.080 Hz vs. 0.895 \ub1 0.084 Hz, p < 0.001, r2 = 0.99) and F2 (1.787 \ub1 0.163 Hz vs. 1.791 \ub1 0.165 Hz, p < 0.001, r2 = 0.97). The SV was 1.84% \ub1 0.66% and it was significantly and moderately correlated with HI (0.082 \ub1 0.028, p < 0.001, r2 = 0.13). The innovative video-based technique of global, markerless gait analysis proposed in our study accurately identifies the main frequency contents and the variability of gait in healthy individuals, thus providing a time-efficient, low-cost means to quantitatively and qualitatively study human locomotion
U3+/LiYF4, a promising IR laser
Under reducing conditions, single crystal of LiYF4 doped with 762 ppm of U3+ were obtained. Absorption and fluorescence spectra of this system are presented as well as the energy level scheme of the lasing transition. Oscillator strength and laser cross section between Stark levels of the [MATH] transition are calculated
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