177 research outputs found

    Epsilon iron oxide: Origin of the high coercivity stable low Curie temperature magnetic phase found in heated archeological materials

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    The identification of epsilon iron oxide (-Fe2O3) as the low Curie temperature high coercivity stable phase (HCSLT) carrying the remanence in heated archeological samples has been achieved in samples from two archeological sites that exhibited the clearest evidence of the presence of the HCSLT. This uncommon iron oxide has been detected by Confocal Raman Spectroscopy (CRS) and characterized by rock magnetic measurements. Large numbers of -Fe2O3 microaggregates (in CO) or isolated clusters (in HEL) could be recognized, distributed over the whole sample, and embedded within the ceramic matrix, along with hematite and pseudobrookite and with minor amounts of anatase, rutile, and maghemite. Curie temperature estimates of around 170 degrees C for CO and 190 degrees C for HEL are lower than for pure, synthetic -Fe2O3 (227 degrees C). This, together with structural differences between the Raman spectra of the archeologically derived and synthetic samples, is likely due to Ti substitution in the -Fe2O3 crystal lattice. The -Fe2O3--Fe2O3--Fe2O3 transformation series has been recognized in heated archeological samples, which may have implications in terms of their thermal history and in the factors that govern the formation of -Fe2O3

    Quantum Arrival Time Formula from Decoherent Histories

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    In the arrival time problem in quantum mechanics, a standard formula that frequently emerges as the probability for crossing the origin during a given time interval is the current integrated over that time interval. This is semiclassically correct but can be negative due to backflow. Here, we show that this formula naturally arises in a decoherent histories analysis of the arrival time problem. For a variety of initial states, we show that histories crossing during different time intervals are approximately decoherent. Probabilities may therefore be assigned and coincide with the standard formula (in a semiclassical approximation), which is therefore positive for these states. However, for initial states for which there is backflow, we show that there cannot be decoherence of histories, so probabilities may not be assigned.Comment: 11 page

    Breakup of 17^{17}F on 208^{208}Pb near the Coulomb barrier

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    Angular distributions of oxygen produced in the breakup of 17^{17}F incident on a 208^{208}Pb target have been measured around the grazing angle at beam energies of 98 and 120 MeV. The data are dominated by the proton stripping mechanism and are well reproduced by dynamical calculations. The measured breakup cross section is approximately a factor of 3 less than that of fusion at 98 MeV. The influence of breakup on fusion is discussed.Comment: 7 pages, 8 figure

    Collisional Velocities and Rates in Resonant Planetesimal Belts

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    We consider a belt of small bodies around a star, captured in one of the external or 1:1 mean-motion resonances with a massive perturber. The objects in the belt collide with each other. Combining methods of celestial mechanics and statistical physics, we calculate mean collisional velocities and collisional rates, averaged over the belt. The results are compared to collisional velocities and rates in a similar, but non-resonant belt, as predicted by the particle-in-a-box method. It is found that the effect of the resonant lock on the velocities is rather small, while on the rates more substantial. The collisional rates between objects in an external resonance are by about a factor of two higher than those in a similar belt of objects not locked in a resonance. For Trojans under the same conditions, the collisional rates may be enhanced by up to an order of magnitude. Our results imply, in particular, shorter collisional lifetimes of resonant Kuiper belt objects in the solar system and higher efficiency of dust production by resonant planetesimals in debris disks around other stars.Comment: 31 pages, 11 figures (some of them heavily compressed to fit into arxiv-maximum filesize), accepted for publication at "Celestial Mechanics and Dynamical Astronomy

    Núcleo de microbiota en el cáncer de pulmón central con enriquecimiento estreptocócico como posible marcador de diagnóstico

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    Background: Dysbiosis in lung cancer has been underexplored. The aim of this study was to define the bacterial and fungal microbiota of the bronchi in central lung cancer and to compare it with that of the oral and intestinal compartments. Methods: Twenty-five patients with central lung cancer and sixteen controls without antimicrobial intake during the previous month were recruited. Bacterial and fungal distribution was determined by massive sequencing of bronchial biopsies and saliva and faecal samples. Complex computational analysis was performed to define the core lung microbiota. Results: Affected and contralateral bronchi of patients have almost identical microbiota dominated by Streptococcus, whereas Pseudomonas was the dominant genera in controls. Oral and pulmonary ecosystems were significantly more similar in patients, probably due to microaspirations. Streptococcal abundance in the bronchi differentiated patients from controls according to a ROC curve analysis (90.9% sensitivity, 83.3% specificity, AUC = 0.897). The saliva of patients characteristically showed a greater abundance of Streptococcus, Rothia, Gemella and Lactobacillus. The mycobiome of controls (Candida) was significantly different from that of patients (Malassezia). Cancer patients’ bronchial mycobiome was similar to their saliva, but different from their contralateral bronchi. Conclusions: The central lung cancer microbiome shows high levels of Streptococcus, and differs significantly in its composition from that of control subjects. Changes are not restricted to tumour tissue, and seem to be the consequence of microaspirations from the oral cavity. These findings could be useful in the screening and even diagnosis of this disease

    Eficacia de una estrategia combinada para mejorar el control del colesterol unido a lipoproteínas de baja densidad en pacientes con hipercolesterolemia. Ensayo clínico aleatorizado

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    Introducción y objetivos: Intervenciones diferentes pueden mejorar el control del colesterol unido a lipoproteínas de baja densidad (cLDL). El objetivo principal era evaluar la eficacia de una intervención combinada para mejorar el control del cLDL de pacientes con hipercolesterolemia. También se evaluó su eficacia para mejorar el cumplimiento (farmacológico, dieta y ejercicio). Métodos: Ensayo clínico aleatorizado, de grupos paralelos y multicéntrico (atención primaria) que incluyó a 358 adultos diagnosticados de hipercolesterolemia con tratamiento previo farmacológico o no. Se comparó a 178 sujetos que recibieron intervención combinada (material escrito, tarjetas autocumplimentadas y mensajes al móvil) frente a 178 controles. La variable principal de resultado fue la proporción de sujetos con adecuado control del cLDL (valores recomendados en las guías europeas de dislipemias y riesgo cardiovascular) a los 24 meses. Resultados: El grupo de intervención mostró una reducción media del cLDL significativamente superior a los 24 meses respecto al control, 23, 8 mg/dl (IC95%, 17, 5-30, 1) y 14, 6 mg/dl (IC95%, 8, 9-20, 4), respectivamente (p = 0, 034). El promedio de la reducción del cLDL fue del 13, 1 ± 28, 6%. La proporción de sujetos con adecuado control al año fue significativamente superior en el grupo de intervención (43, 7 frente a 30, 1%; p = 0, 011; RR = 1, 46). En el grupo de intervención, el cumplimiento farmacológico fue significativamente superior (77, 2 frente a 64, 1%; p = 0, 029) y de la práctica de ejercicio (64, 9 frente a 35, 8%; p < 0, 001), aunque no de la dieta. Conclusiones: La intervención combinada consigue una reducción significativa de las cifras de cLDL (superior al 13% al cabo de 2 años) y mejora el grado de control de pacientes con hipercolesterolemia al año. Introduction and objectives: Several interventions can improve low-density lipoprotein cholesterol (LDL-C) control. Our main objective was to evaluate the efficacy of a combined intervention to improve LDL-C control in patients with hypercholesterolemia. The study also assessed the efficacy of the intervention in improving adherence (pharmacological, diet, and exercise). Methods: A multicenter, parallel group, randomized clinical trial (primary care) was conducted in 358 adults diagnosed with hypercholesterolemia, whether receiving prior drug therapy or not. We compared 178 participants who received the combined intervention (written material, self-completed registration cards, and messages to mobile telephones) with 178 controls. The main outcome variable was the proportion of participants with adequate LDL-C control (target levels of the European guidelines on dyslipidemia and cardiovascular risk) at 24 months. Results: At 24 months, the mean reduction in LDL-C was significantly higher in the intervention group (23.8 mg/dL [95%CI, 17.5-30.1]) than in the control group (14.6 mg/dL [95%CI, 8.9-20.4]; P = .034). The mean LDL-C decrease was 13.1% +/- 28.6%. At 1 year, the proportion of participants with adequate control was significantly higher in the intervention group than in the control group (43.7% vs 30.1%; P = .011; RR, 1.46). Adherence was significantly higher in the intervention group, both to drug therapy (77.2% vs 64.1%; P = .029) and exercise (64.9% vs 35.8; P < .001), but not to diet. Conclusions: The combined intervention significantly reduced LDL-C (by more than 13% at 2 years) and improved the degree of LDL-C control in patients with hypercholesterolemia at 1 year

    Molecular-assisted selection for resistance to cassava mosaic disease in Manihot esculenta Crantz

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    The geminivirus complex known as cassava mosaic disease (CMD) is one of the most devastating viruses for cassava (Manihot esculenta Crantz). The aim of this study was to use molecular-assisted selection (MAS) to identify CMD-resistant accessions and ascertain promising crosses with elite Brazilian varieties. One thousand two hundred twenty-four accessions were genotyped using five molecular markers (NS169, NS158, SSRY028, SSRY040 and RME1) that were associated with resistance to CMD, along with 402 SNPs (single-nucleotide polymorphism). The promising crosses were identified using a discriminant analysis of main component (DAPC), and the matrix of genomic relationship was estimated with SNP markers. The CMD1 gene, previously described in M. glaziovii, was not found in M. esculenta. In contrast, the CMD2 gene was found in 5, 4 and 5 % of cassava accessions, with flanking markers NS169+RME1, NS158+RME1 and SSRY28+RME1, respectively. Only seven accessions presented all markers linked to the CMD resistance. The DAPC of the seven accessions along with 17 elite cassava varieties led to the formation of three divergent clusters. Potential sources of resistance to CMD were divided into two groups, while the elite varieties were distributed into three groups. The low estimates of the genomic relationship (ranging from -0.167 to 0.681 with an average of 0.076) contributed to the success in identifying contrasting genotypes. The use of MAS in countries where CMD is a quarantine disease constitutes a successful strategy not only for identifying the resistant accessions but also for determining the promising crosses

    An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics

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    For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types

    X chromosome inactivation does not necessarily determine the severity of the phenotype in Rett syndrome patients

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    Rett syndrome (RTT) is a severe neurological disorder usually caused by mutations in the MECP2 gene. Since the MECP2 gene is located on the X chromosome, X chromosome inactivation (XCI) could play a role in the wide range of phenotypic variation of RTT patients; however, classical methylation-based protocols to evaluate XCI could not determine whether the preferentially inactivated X chromosome carried the mutant or the wild-type allele. Therefore, we developed an allele-specific methylation-based assay to evaluate methylation at the loci of several recurrent MECP2 mutations. We analyzed the XCI patterns in the blood of 174 RTT patients, but we did not find a clear correlation between XCI and the clinical presentation. We also compared XCI in blood and brain cortex samples of two patients and found differences between XCI patterns in these tissues. However, RTT mainly being a neurological disease complicates the establishment of a correlation between the XCI in blood and the clinical presentation of the patients. Furthermore, we analyzed MECP2 transcript levels and found differences from the expected levels according to XCI. Many factors other than XCI could affect the RTT phenotype, which in combination could influence the clinical presentation of RTT patients to a greater extent than slight variations in the XCI pattern

    Reperfusion treatment in acute ischaemic stroke due to cervical and cerebral artery dissection: results of a Spanish national multicentre study

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    Introducción: El ictus isquémico (II) por disección arterial cervicocerebral (DAC) es una entidad infrecuente y existen pocos datos sobre el uso de terapias de reperfusión como la fibrinólisis intravenosa y la trombectomía mecánica. Se analizó el uso de dichas terapias en pacientes con II por DAC y se comparó con aquellos pacientes reperfundidos con II por otras causas. Método: Estudio observacional retrospectivo multicéntrico de pacientes con II por DAC basado en el Registro Nacional de Ictus de la Sociedad Española de Neurología durante el periodo 2011-2019. Se realizaron análisis comparativos entre: a) pacientes con DAC tratados y no tratados con terapias de reperfusión y b) pacientes reperfundidos con II por DAC y pacientes reperfundidos con II por otras causas. Se incluyeron variables epidemiológicas, del ictus y resultados al alta y a los 3 meses. Resultados: Un total de 21.037 pacientes con II fueron incluidos; 223 (1%) fueron por DAC y 68 (30%) recibieron tratamiento de reperfusión. El uso de tratamientos de reperfusión fue menor en los casos de DAC de arteria vertebral y mayor en los casos de oclusión carotídea. Los pacientes con II por DAC reperfundidos respecto a aquellos con II reperfundidos por otras causas fueron más jóvenes, la trombectomía mecánica se utilizó más y la fibrinólisis intravenosa menos. Las complicaciones hemorrágicas, la mortalidad y la autonomía a los 3 meses fueron similares. Conclusiones: Las terapias de reperfusión se usan con frecuencia en los pacientes con II por DAC. Los resultados demuestran eficacia y seguridad y son equiparables a los pacientes tratados con terapias de reperfusión por II de otras causas.Introduction: Ischaemic stroke (IS) due to cervical and cerebral artery dissection (CAD) is a rare entity, and few data are available on the use of such reperfusion therapies as intravenous fibrinolysis and mechanical thrombectomy in these patients. We analysed the use of these treatments in patients with IS due to CAD and compared them against patients receiving reperfusion treatment for IS of other aetiologies. Method: We conducted an observational, retrospective, multicentre study of patients with IS due to CAD recorded in the National Stroke Registry of the Spanish Society of Neurology during the period 2011-2019. Comparative analyses were performed between: a) patients with CAD treated and not treated with reperfusion therapies and b) patients treated with reperfusion for IS due to CAD and patients treated with reperfusion for IS due to other causes. Epidemiological data, stroke variables, and outcomes at discharge and at 3 months were included in the analysis. Results: The study included 21,037 patients with IS: 223 (1%) had IS due to CAD, of whom 68 (30%) received reperfusion treatment. Reperfusion treatments were used less frequently in cases of vertebral artery dissection and more frequently in patients with carotid artery occlusion. Compared to patients with IS due to other causes, patients with CAD were younger, more frequently underwent mechanicalthrombectomy, and less frequently received intravenous fibri nolysis. Rates of haemorrhagic complications, mortality, and independence at 3 months were similar in both groups. Conclusions: Reperfusion therapy is frequently used in patients with IS due to CAD. The outcomes of these patients demonstrate the efficacy and safety of reperfusion treatments, and are comparable to the outcomes of patients with IS due to other aetiologie
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