7,310 research outputs found

    Experimental evidence of delocalized states in random dimer superlattices

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    We study the electronic properties of GaAs-AlGaAs superlattices with intentional correlated disorder by means of photoluminescence and vertical dc resistance. The results are compared to those obtained in ordered and uncorrelated disordered superlattices. We report the first experimental evidence that spatial correlations inhibit localization of states in disordered low-dimensional systems, as our previous theoretical calculations suggested, in contrast to the earlier belief that all eigenstates are localized.Comment: 4 pages, 5 figures. Physical Review Letters (in press

    Infratentorial hygroma secondary to decompressive craniectomy after cerebellar infarction

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    We present a case of expansive CSF collection in the cerebellar convexity. The patient was a 74 years old lady who one month before had suffered a cerebellar infarct complicated with acute hydrocephalus. She had good evolution after decompressive craniectomy without shunting. Fifteen days after surgery, the patient started with new positional vertigo, nausea and vomiting and a wound CSF fistula that needed ventriculoperitoneal shunt (medium pressure) because conservative treatment failed. After shunting, the fistula closed, but the patient symptoms worsened. The MRI showed normal ventricular size with a cerebellar hygroma, extending to the posterior interhemispheric fissure. The collection had no blood signal and expanded during observation. A catheter was implanted in the collection and connected to the shunt. The patient became asymptomatic after surgery, and the hygromas had disappeared in control CT at one month. This case shows an infrequent problem of CSF circulation at posterior fossa that resulted in vertigo of central origin. A higroma-ventricle-peritoneal shunt solved the symptoms of the patient

    On the Stability of Quasi-Equilibrium Self-Gravitating Configurations in a Tidal Field

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    The possibility that quasi-equilibrium self-gravitating galaxy-like configurations exist in a tidal field is analyzed in this paper. More specifically, we address the question of how to predict initial configurations modeling galaxies that are able to survive environmental effects in a dense environment for a Hubble time or so, provided thay dynamical friction is neglected. The initial quasi-equilibrium configurations have been built up taking into account the external tidal field produced by the halo. It modifies the escape velocity field of the configuration, compared with isolated configurations. The survival of the configurations as they orbit inside the halos has been studied through N-body simulations. As a general result, it has been found out that the bulk of the models is conserved along 12.5 Gyears of evolution, and that the low rates of mass losses they experience are consistent with those expected when the adiabatic protection hypothesis is at work. So, solutions for galaxy configurations in tidal quasi-equilibrium have been found, showing that tidal stripping in quiescent phases does not seem to be very important, unless that the density of the galaxy environment at its formation had been much lower than that of the galaxy environment at the point of its orbit where the tidal perturbation is maximum. (Abridged)Comment: 36 pages, 7 postscript figures, to be published in Ap

    Breast Cancer Mortality in Older and Younger Patients in California

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    BACKGROUND: Breast cancer in younger patients is reported to be more aggressive and associated with lower survival; however, factors associated with age-specific mortality differences have not been adequately assessed. METHODS: We used data from the population-based California Cancer Registry for 38,509 younger (18-49 years) and 121,573 older (50 years and older) women diagnosed with stage I to III breast cancer, 2005-2014. Multivariable Cox regression models were used to estimate breast cancer-specific mortality rate ratios (MRR) and 95% confidence intervals (CI), stratified by tumor subtype, guideline treatment, and care at an NCI-designated cancer center (NCICC). RESULTS: Older breast cancer patients at diagnosis experienced 17% higher disease-specific mortality than younger patients, after multivariable adjustment (MRR = 1.17; 95% CI, 1.11-1.23). Higher MRRs (95% CI) were observed for older versus younger patients with hormone receptor (HR)(+)/HER2(-) (1.24; 1.14-1.35) and HR(+)/HER2(+) (1.38; 1.17-1.62), but not for HR(-)/HER2(+) (HR = 0.94; 0.79-1.12) nor triple-negative breast cancers (1.01; 0.92-1.11). The higher mortality in older versus younger patients was diminished among patients who received guideline-concordant treatment (MRR = 1.06; 95% CI, 0.99-1.14) and reversed among those seen at an NCICC (MRR = 0.86; 95% CI, 0.73-1.01). CONCLUSIONS: Although younger women tend to be diagnosed with more aggressive breast cancers, adjusting for these aggressive features results in older patients having higher mortality than younger patients, with variations by age, tumor subtype, receipt of guideline treatment, and being cared for at an NCICC. IMPACT: Higher breast cancer mortality in older compared with younger women could partly be addressed by ensuring optimal treatment and comprehensive patient-centered care

    Electromagnetic vertex function of the pion at T > 0

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    The matrix element of the electromagnetic current between pion states is calculated in quenched lattice QCD at a temperature of T=0.93TcT = 0.93 T_c. The nonperturbatively improved Sheikholeslami-Wohlert action is used together with the corresponding O(a){\cal O}(a) improved vector current. The electromagnetic vertex function is extracted for pion masses down to 360MeV360 {\rm MeV} and momentum transfers Q2≀2.7GeV2Q^2 \le 2.7 {\rm GeV}^2.Comment: 17 pages, 8 figure

    DualSPHysics: from fluid dynamics to multiphysics problems

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    DualSPHysics is a weakly compressible smoothed particle hydrodynamics (SPH) Navier–Stokes solver initially conceived to deal with coastal engineering problems, especially those related to wave impact with coastal structures. Since the first release back in 2011, DualSPHysics has shown to be robust and accurate for simulating extreme wave events along with a continuous improvement in efficiency thanks to the exploitation of hardware such as graphics processing units for scientific computing or the coupling with wave propagating models such as SWASH and OceanWave3D. Numerous additional functionalities have also been included in the DualSPHysics package over the last few years which allow the simulation of fluid-driven objects. The use of the discrete element method has allowed the solver to simulate the interaction among different bodies (sliding rocks, for example), which provides a unique tool to analyse debris flows. In addition, the recent coupling with other solvers like Project Chrono or MoorDyn has been a milestone in the development of the solver. Project Chrono allows the simulation of articulated structures with joints, hinges, sliders and springs and MoorDyn allows simulating moored structures. Both functionalities make DualSPHysics especially suited for the simulation of offshore energy harvesting devices. Lately, the present state of maturity of the solver goes beyond single-phase simulations, allowing multi-phase simulations with gas–liquid and a combination of Newtonian and non-Newtonian models expanding further the capabilities and range of applications for the DualSPHysics solver. These advances and functionalities make DualSPHysics an advanced meshless solver with emphasis on free-surface flow modelling

    Sublayer- and cell-type-specific neurodegenerative transcriptional trajectories in hippocampal sclerosis

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    Altres ajuts: FundaciĂłn Tatiana PĂ©rez de Guzman el Bueno; SynCogDis Network (SAF2014-52624-REDT, SAF2017-90664-REDT); Human Frontiers Science Program (HFSP RGP0022/2013); Fondo Europeo de Desarrollo Regional (FEDER).Hippocampal sclerosis, the major neuropathological hallmark of temporal lobe epilepsy, is characterized by different patterns of neuronal loss. The mechanisms of cell-type-specific vulnerability and their progression and histopathological classification remain controversial. Using single-cell electrophysiology in vivo and immediate-early gene expression, we reveal that superficial CA1 pyramidal neurons are overactive in epileptic rodents. Bulk tissue and single-nucleus expression profiling disclose sublayer-specific transcriptomic signatures and robust microglial pro-inflammatory responses. Transcripts regulating neuronal processes such as voltage channels, synaptic signaling, and cell adhesion are deregulated differently by epilepsy across sublayers, whereas neurodegenerative signatures primarily involve superficial cells. Pseudotime analysis of gene expression in single nuclei and in situ validation reveal separated trajectories from health to epilepsy across cell types and identify a subset of superficial cells undergoing a later stage in neurodegeneration. Our findings indicate that sublayer- and cell-type-specific changes associated with selective CA1 neuronal damage contribute to progression of hippocampal sclerosis

    Role of proton pump inhibitors dosage and duration in Helicobacter pylori eradication treatment: Results from the European Registry on H. pylori management

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    Background: Management of Helicobacter pylori (H. pylori) infection requires co-treatment with proton pump inhibitors (PPIs) and the use of antibiotics to achieve successful eradication. Aim: To evaluate the role of dosage of PPIs and the duration of therapy in the effectiveness of H. pylori eradication treatments based on the ‘European Registry on Helicobacter pylori management’ (Hp-EuReg). Methods: Hp-EuReg is a multicentre, prospective, non-interventionist, international registry on the routine clinical practice of H. pylori management by European gastroenterologists. All infected adult patients were systematically registered from 2013 to 2022. Results: Overall, 36,579 patients from five countries with more than 1000 patients were analysed. Optimal (≄90%) first-line-modified intention-to-treat effectiveness was achieved with the following treatments: (1) 14-day therapies with clarithromycin-amoxicillin-bismuth and metronidazole-tetracycline-bismuth, both independently of the PPI dose prescribed; (2) All 10-day (except 10-day standard triple therapy) and 14-day therapies with high-dose PPIs; and (3) 10-day quadruple therapies with clarithromycin-amoxicillin-bismuth, metronidazole-tetracycline-bismuth, and clarithromycin-amoxicillin-metronidazole (sequential), all with standard-dose PPIs. In first-line treatment, optimal effectiveness was obtained with high-dose PPIs in all 14-day treatments, in 10- and 14-day bismuth quadruple therapies and in 10-day sequential with standard-dose PPIs. Optimal second-line effectiveness was achieved with (1) metronidazole-tetracycline-bismuth quadruple therapy for 14- and 10 days with standard and high-dose PPIs, respectively; and (2) levofloxacin-amoxicillin triple therapy for 14 days with high-dose PPIs. None of the 7-day therapies in both treatment lines achieved optimal effectiveness. Conclusions: We recommend, in first-line treatment, the use of high-dose PPIs in 14-day triple therapy and in 10-or 14-day quadruple concomitant therapy in first-line treatment, while standard-dose PPIs would be sufficient in 10-day bismuth quadruple therapies. On the other hand, in second-line treatment, high-dose PPIs would be more beneficial in 14-day triple therapy with levofloxacin and amoxicillin or in 10-day bismuth quadruple therapy either as a three-in-one single capsule or in the traditional scheme

    The role of statins on helicobacter pylori eradication: Results from the european registry on the management of h. pylori (hp-eureg)

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    Statins could increase the effectiveness of Helicobacter pylori eradication therapies due to their anti-inflammatory effect. The aim of this study was to analyze the impact of this therapeutic association in real life. This is a multicenter, prospective, non-interventional study aimed at evaluating the management of H. pylori by European gastroenterologists. Patients were registered in an e-CRF by AEG-REDCap from 2013 to 2020. The association between statin use and H. pylori eradication effectiveness was evaluated through multivariate analysis. Overall, 9988 and 705 patients received empirical and culture-guided treatment, respectively. Overall, statin use was associated with higher effectiveness in the empirical group (OR = 1.3; 95%CI = 1.1-1.5), but no association was found with first-line treatment effectiveness (N = 7738); as an exception, statin use was specifically associated with lower effectiveness of standard triple therapy (OR = 0.76; 95%CI = 0.59-0.99). In the rescue therapy empirical group (N = 2228), statins were associated with higher overall effectiveness (OR = 1.9; 95%CI = 1.4-2.6). However, sub-analyses by treatment schemes only confirmed this association for the single-capsule bismuth quadruple therapy (OR = 2.8; 95%CI = 1.3-5.7). No consistent association was found between statin use and H. pylori therapy effectiveness. Therefore, the addition of statins to the usual H. pylori treatment cannot be currently recommended to improve cure rates. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
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