15,287 research outputs found
Evidence for entanglement at high temperatures in an engineered molecular magnet
The molecular compound
[Fe(-oxo)(CHN)(CO)]
was designed and synthesized for the first time and its structure was
determined using single-crystal X-ray diffraction. The magnetic susceptibility
of this compound was measured from 2 to 300 K. The analysis of the
susceptibility data using protocols developed for other spin singlet
ground-state systems indicates that the quantum entanglement would remain at
temperatures up to 732 K, significantly above the highest entanglement
temperature reported to date. The large gap between the ground state and the
first-excited state (282 K) suggests that the spin system may be somewhat
immune to decohering mechanisms. Our measurements strongly suggest that
molecular magnets are promising candidate platforms for quantum information
processing
Evidence for a Variable Ultrafast Outflow in the Newly Discovered Ultraluminous Pulsar NGC 300 ULX-1
Ultraluminous pulsars are a definite proof that persistent super-Eddington
accretion occurs in nature. They support the scenario according to which most
Ultraluminous X-ray Sources (ULXs) are super-Eddington accretors of stellar
mass rather than sub-Eddington intermediate mass black holes. An important
prediction of theories of supercritical accretion is the existence of powerful
outflows of moderately ionized gas at mildly relativistic speeds. In practice,
the spectral resolution of X-ray gratings such as RGS onboard XMM-Newton is
required to resolve their observational signatures in ULXs. Using RGS, outflows
have been discovered in the spectra of 3 ULXs (none of which are currently
known to be pulsars). Most recently, the fourth ultraluminous pulsar was
discovered in NGC 300. Here we report detection of an ultrafast outflow (UFO)
in the X-ray spectrum of the object, with a significance of more than
3{\sigma}, during one of the two simultaneous observations of the source by
XMM-Newton and NuSTAR in December 2016. The outflow has a projected velocity of
65000 km/s (0.22c) and a high ionisation factor with a log value of 3.9. This
is the first direct evidence for a UFO in a neutron star ULX and also the first
time that this its evidence in a ULX spectrum is seen in both soft and hard
X-ray data simultaneously. We find no evidence of the UFO during the other
observation of the object, which could be explained by either clumpy nature of
the absorber or a slight change in our viewing angle of the accretion flow.Comment: 10 pages, 4 figures. Accepted to MNRA
Electron cloud buildup and impedance effects on beam dynamics in the future circular e+e− collider and experimental characterization of thin TiZrV vacuum chamber coatings
The Future Circular Collider FCC-ee is a study toward a high luminosity electron-positron collider with a centre-of-mass energy from 91 GeV to 365 GeV. Due to the beam parameters and pipe dimensions, collective effects and electron cloud can be very critical aspects for the machine and can represent the main limitations to its performance. An estimation of the electron cloud build up in the main machine components and an impedance model are required to analyze the induced instabilities and to find solutions for their mitigation. Special attention has been given to the resistive wall impedance associated with a layer of nonevaporable getter (NEG) coating on the vacuum chamber required for electron cloud mitigation. The studies presented in this paper will show that minimizing the thickness of this coating layer is mandatory to increase the single bunch instability thresholds in the proposed lepton collider at 45.6 GeV. For this reason, NEG thin films with thicknesses below 250 nm have been investigated by means of numerical simulations to minimize the resistive wall impedance. In parallel, an extensive measurement campaign was performed at CERN to characterize these thin films, with the purpose of finding the minimum effective thickness satisfying vacuum and electron cloud requirements
Retrogression and re-ageing of 7075 aluminium alloy : microstructural characterization
Industrial Summary: The 7075 aluminium alloy presents a low stress corrosion cracking strength when aged to achieve maximum
mechanical strength, T6 temper; high stress corrosion cracking strength is attained with overageing, T7 temper; but with loss of mechanical strength. Retrogression and re-ageing treatments improves the stress corrosion behaviour of the alloy whilst maintaining the mechanical resistance of the T6 temper. The microstructures produced by the retrogression and re-ageing treatments were characterized in this study by
transmission electron microscopy, electron diffraction and differential scanning calorimetry. The precipitation is extremely Æne and distributed homogeneously inside the grains, being slightly denser and more stable than that resulting from the T6 temper; whilst the grain boundary precipitation is quite different from that resulting from T6 treatment, the particles being coarser, and much closer to the precipitation resulting from T7 temper. The retrogression temperature is the main property controlling factor; a higher retrogression temperature, increasing the dissolution degree, promotes the formation of more stable precipitates on re-ageing
Fertility preservation in ovarian tumours
A considerable number of patients with a cancer diagnosis are of childbearing age and have not satisfied their desire for a family. Despite ovarian cancer (OC) usually occurring in older patients, 3%–14% are diagnosed at a fertile age with the overall 5-year survival rate being 91.2% in women ≤44 years of age when it is found at 1A–B stage. In this scenario, testing the safety and the efficacy of fertility sparing strategies in OC patients is very important overall in terms of quality of life. Unfortunately, the lack of randomised trials to validate conservative approaches does not guarantee the safety of fertility preservation strategies. However, evidence-based data from descriptive series suggest that in selected cases, the preservation of the uterus and at least one part of the ovary does not lead to a high risk of relapse. This conservative surgery helps to maintain organ function, giving patients of childbearing age the possibility to preserve their fertility. We hereby analysed the main evidence from the international literature on this topic in order to highlight the selected criteria for conservative management of OC patients, including healthy BRCA mutations carriers
Desempenho de linhagens obtidas na seleção recorrente fenotípica para porte ereto do feijoeiro.
Um programa de seleção recorrente (SR) fenotípica para plantas de porte ereto vem sendo conduzido na Universidade Federal de Lavras. Para isso, as plantas mais eretas da população segregante são intercruzadas. As sementes hibridas obtidas são multiplicadas em bulk na geração ?F1? e na próxima geração ?F2? o processo se repete. A cada três ciclos, a população segregante é avançada até a obtenção de linhagens, avaliando o porte, produtividade e tipo de grão. O presente trabalho teve como objetivo avaliar as cinco melhores linhagens do ciclo (CV) e do (CVIII) da SR
A new method for the solution of the Schrodinger equation
We present a new method for the solution of the Schrodinger equation
applicable to problems of non-perturbative nature. The method works by
identifying three different scales in the problem, which then are treated
independently: An asymptotic scale, which depends uniquely on the form of the
potential at large distances; an intermediate scale, still characterized by an
exponential decay of the wave function and, finally, a short distance scale, in
which the wave function is sizable. The key feature of our method is the
introduction of an arbitrary parameter in the last two scales, which is then
used to optimize a perturbative expansion in a suitable parameter. We apply the
method to the quantum anharmonic oscillator and find excellent results.Comment: 4 pages, 4 figures, RevTex
Effects of substituting ytterbium for scandium on corrosion behaviour of Al-Sc alloy
The localized corrosion and electrochemical behaviour of Al-0.28 wt.% Sc and Al-0.24 wt.% Sc-0.07 wt.% Yb alloys have been studied in 3.5 wt.% NaCl solution. The results showed that the impurity intermetallic phases containing Fe can act as cathodes and promote localized corrosion in the surrounding matrix. Yb had strong effect on the polarization behaviour in the anodic domain of Al-Sc alloy by improving the pitting corrosion resistance of this alloy. It has been deduced that a high number density of fully coherent nano-sized Al3Sc or Al-3(Sc, Yb) precipitates in heat treated alloys can enhance the passivation tendency of these alloys.This research was supported by The Project Bridging The Gap, funded by the Erasmus Mundus External Cooperation Window Program. Acknowledgements also to the University of Minho, for the provision of research facilitiesinfo:eu-repo/semantics/publishedVersio
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