2,176 research outputs found
A unified evaluation of iterative projection algorithms for phase retrieval
Iterative projection algorithms are successfully being used as a substitute
of lenses to recombine, numerically rather than optically, light scattered by
illuminated objects. Images obtained computationally allow aberration-free
diffraction-limited imaging and the possibility of using radiation for which no
lenses exist. The challenge of this imaging technique is transfered from the
lenses to the algorithms. We evaluate these new computational ``instruments''
developed for the phase retrieval problem, and discuss acceleration strategies.Comment: 12 pages, 9 figures, revte
Normal zone in -coated conductors
We consider the distribution of an electric field in YBCO-coated conductors
for a situation in which the DC transport current is forced into the copper
stabilizer due to a weak link -- a section of the superconducting film with a
critical current less than the transport current. The electric field in the
metal substrate is also discussed. The results are compared with recent
experiments on normal zone propagation in coated conductors for which the
substrate and stabilizer are insulated from each other. The potential
difference between the substrate and stabilizer, and the electric field in the
substrate outside the normal zone can be accounted for by a large screening
length in the substrate, comparable to the length of the sample. During a
quench, the electric field inside the interface between YBCO and stabilizer, as
well as in the buffer layer, can be several orders of magnitude greater than
the longitudinal macroscopic electric field inside the normal zone. We
speculate on the possibility of using possible microscopic electric discharges
caused by this large (kV/cm) electric field as a means to detect a
quench.Comment: 8 pages, 4 figure
The effects of superconductor-stabilizer interfacial resistance on quench of a pancake coil made out of coated conductor
We present the results of numerical analysis of normal zone propagation in a
stack of coated conductors which imitates a pancake coil.
Our main purpose is to determine whether the quench protection quality of such
coils can be substantially improved by increased contact resistance between the
superconducting film and the stabilizer. We show that with increased contact
resistance the speed of normal zone propagation increases, the detection of a
normal zone inside the coil becomes possible earlier, when the peak temperature
inside the normal zone is lower, and stability margins shrink. Thus, increasing
contact resistance may become a viable option for improving the prospects of
coated conductors for high magnets applications.Comment: 9 pages, 4 figure
The effects of superconductor-stabilizer interfacial resistance on quench of current-carrying coated conductor
We present the results of numerical analysis of a model of normal zone
propagation in coated conductors. The main emphasis is on the effects of
increased contact resistance between the superconducting film and the
stabilizer on the speed of normal zone propagation, the maximum temperature
rise inside the normal zone, and the stability margins. We show that with
increasing contact resistance the speed of normal zone propagation increases,
the maximum temperature inside the normal zone decreases, and stability margins
shrink. This may have an overall beneficial effect on quench protection quality
of coated conductors. We also briefly discuss the propagation of solitons and
development of the temperature modulation along the wire.Comment: To be published in Superconductor Science and Technology. This
preprint contains one animated figure (Fig. 6(a)). when asked whether you
want to play the content, click "Play". Acrobat Reader (Windows and Mac, but
not Linux) will play embedded flash movies. In the printed copy Fig. 6(b)
will show the temperature profile at gamma t=15
Evaluation of p53 protein expression as a marker for long-term prognosis in colorectal carcinoma.
Mutation of the p53 gene is reported to be of prognostic importance in colorectal carcinomas. Immunohistochemical staining of the accumulated p53 gene product may be a simple alternative for p53 mutation analysis. Previous studies addressing the prognostic importance of p53 expression, however, yielded contradictory results. Therefore, we evaluated the importance of p53 expression as a marker for long-term prognosis in a well-characterised study population of 109 colorectal carcinomas. After antigen retrieval with target unmasking fluid (TUF), immunostaining of p53 was performed with both monoclonal antibody DO7 and polyclonal antibody CM1. Objective quantification of the p53 signal was assessed by a computerised image analyser. p53 expression was higher in non-mucinous tumours than in mucinous tumours (p53 labelling index = 30% and 17% respectively, P = 0.05), and in metastatic tumours compared with non-metastatic tumours (p53 labelling index = 37% and 22% respectively, P = 0.05). Other histopathological features were not related to p53 expression. In multivariate analysis, Dukes' stage (P = 0.02) and histological grade (P = 0.05) stood out as independent markers for prognosis. p53 expression was not an independent marker for prognosis. At present, p53 expression is not a useful marker for long-term prognosis. Further insight into the relationship between p53 mutations and p53 expression is needed to elucidate more precisely the clinical relevance of p53 alterations
Force-matched embedded-atom method potential for niobium
Large-scale simulations of plastic deformation and phase transformations in
alloys require reliable classical interatomic potentials. We construct an
embedded-atom method potential for niobium as the first step in alloy potential
development. Optimization of the potential parameters to a well-converged set
of density-functional theory (DFT) forces, energies, and stresses produces a
reliable and transferable potential for molecular dynamics simulations. The
potential accurately describes properties related to the fitting data, and also
produces excellent results for quantities outside the fitting range. Structural
and elastic properties, defect energetics, and thermal behavior compare well
with DFT results and experimental data, e.g., DFT surface energies are
reproduced with less than 4% error, generalized stacking-fault energies differ
from DFT values by less than 15%, and the melting temperature is within 2% of
the experimental value.Comment: 17 pages, 13 figures, 7 table
The human ZC3H3 and RBM26/27 proteins are critical for PAXT-mediated nuclear RNA decay
Recruitment of the human ribonucleolytic RNA exosome to nuclear polyadenylated (pA(+)) RNA is facilitated by the Poly(A) Tail eXosome Targeting (PAXT) connection. Besides its core dimer, formed by the exosome co-factor MTR4 and the ZFC3H1 protein, the PAXT connection remains poorly defined. By characterizing nuclear pA(+)-RNA bound proteomes as well as MTR4-ZFC3H1 containing complexes in conditions favoring PAXT assembly, we here uncover three additional proteins required for PAXT function: ZC3H3, RBM26 and RBM27 along with the known PAXT-associated protein, PABPN1. The zinc-finger protein ZC3H3 interacts directly with MTR4-ZFC3H1 and loss of any of the newly identified PAXT components results in the accumulation of PAXT substrates. Collectively, our results establish new factors involved in the turnover of nuclear pA(+) RNA and suggest that these are limiting for PAXT activity
Widely-tunable mid-infrared ring cavity pump-enhanced OPO and application in photo-thermal interferometric trace ethane detection
Funding: Innovate UK (133076); Engineering and Physical Sciences Research Council (EP//L01596X/1, EP/M01326X/1, EP/M024385/1); European Research Council (ERC-2018-STG 803665).The development of a broadly and accurately tunable single-frequency mid-infrared laser source and its application to a sensitive laser absorption detection method are described. Photo-thermal interferometric spectroscopy is employed as a phase-sensitive method to detect the minute refractive index change caused by the heating of a gas under laser radiation. A separate probe beam allows for the spectrally-interesting mid-infrared region to be examined whilst utilizing low cost, high detectivity photodetectors in the visible/near-infrared region. We also describe the implementation of a Sagnac interferometer to minimize the effects of environmental perturbation and provide inherent passive stability. A continuous-wave ring-cavity pump-enhanced OPO has been developed to provide excitation light from 3–4 µm at 140 mW with the ability to mode-hop tune continuously over 90 cm−1 in 0.07 cm−1 steps. Complementary use of both detection apparatus and excitation source has allowed for presence of ethane to be detected down to 200 parts per billion.developed to provide excitation light from 3–4 µm at 140 mW with the ability to mode-hop tune continuously over 90 cm−1 in 0.07 cm−1 steps. Complementary use of both detection apparatus and excitation source has allowed for presence of ethane to be detected down to 200 parts per billion.Publisher PDFPeer reviewe
ATHLOS Healthy Aging Scale score as the predictor of all-cause mortality in Poland and Czechia
Background: The ATHLOS consortium (Aging Trajectories of Health-Longitudinal Opportunities and Synergies) used data from several aging cohorts to develop a novel scale measuring healthy aging comprehensively and globally (ATHLOS Healthy Aging Scale). In the present study, we assessed the predictive performance of the ATHLOS Healthy Aging Scale for all-cause mortality in middle-aged and older adults. Methods: Data from the Polish and Czech HAPIEE (Health Alcohol and Psychosocial factors In Eastern Europe) prospective cohorts were used. There were 10,728 Poles and 8,857 Czechs recruited. The ATHLOS Healthy Aging Scale score was calculated for all participants using data from the baseline examination carried out from 2002 to 2005. The follow-up for all-cause mortality was completed over 14 years. The associations between quintiles of the ATHLOS Healthy Aging Scale and all-cause mortality were estimated using Cox proportional hazards models. Results: A total of 9,922 Polish and 8,518 Czech participants contributed ATHLOS Healthy Aging Scale and mortality data with 1,828 and 1,700 deaths, respectively. After controlling for age, the ATHLOS Healthy Aging Scale score was strongly associated with mortality in a graded fashion for both genders and countries (hazard ratios for lowest vs. highest quintile were 2.98 and 1.96 for Czech and Polish women and 2.83 and 2.66 for Czech and Polish men, respectively). The associations were only modestly attenuated by controlling for education, economic activity, and smoking, and there was further modest attenuation after additional adjustment for self-rated health. Conclusion: The novel ATHLOS Healthy Aging Scale is a good predictor of all-cause mortality in Central European urban populations, suggesting that this comprehensive measure is a useful tool for the assessment of the future health trajectories of older persons
Resonance phenomena in asymmetric superconducting quantum interference devices
Theory of self induced resonances in asymmetric two-junction interferometer
device is presented. In real devices it is impossible to have an ideal
interferometer free of imperfections. Thus, we extended previous theoretical
approaches introducing a model which contains several asymmetries: Josephson
current , capacitances and dissipation presented in an
equivalent circuit. Moreover, non conventional symmetry of the order parameter
in high temperature superconducting quantum interference devices forced us to
include phase asymmetries. Therefore, the model has been extended to the case
of -shift interferometers, where a phase shift is present in one of the
junctions.Comment: accepted to PRB, low quality figure
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