5,853 research outputs found

    Multibody neutrino exchange in a neutron star: neutrino sea and border effects

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    The interaction due to the exchange of massless neutrinos between neutrons is a long-range force. Border effects on this multibody exchange inside a dense core are studied and computed analytically in 1 + 1 dimensions. We demonstrate in this work that a proper treatment of the star's border effect automatically incorporates the condensate contribution as a consequence of the appropriate boundary conditions for the neutrino Feynman propagator inside the star. The total multibody exchange contribution is infrared-safe and vanishes exactly in 1 + 1 dimensions. The general conclusion of this work is that the border effect does not modify the result that neutrino exchange is infrared-safe. This toy model prepares the ground and gives the tools for the study of the realistic 3 + 1 star.Comment: Latex file (Revtex), 11 pages, 2 figure

    Characterization of Mathematical Reasoning Skills in Children with ADHD

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    The objective of the present research was to characterize the mathematical reasoning skills in children with ADHD between 7 and 9 years old. The study begins with the conception of children with special needs and an anthropological research is carried out in perspectives of the actor on mathematical reasoning skills and interviews of their three teachers about their difficulties, alterations and disorders. The research method is an ethnographic fieldwork. The results show lack of mathematical skills specifically in numerical calculation; observing disorder, combination of simultaneous operation between addition and subtraction, attention deficit during the reading of a problem so they fail to systematize, identify data for algorithmic operationsEl objetivo de la presente investigación fue caracterizar las habilidades del razonamiento matemático en niños con TDAH entre 7 a 9 años, el estudio inicia de la concepción de niños con necesidades especiales y se realiza una indagación antropológica en perspectivas del actor sobre las habilidades del razonamiento matemático y las entrevista a sus tres docentes acerca de sus dificultades, alteraciones y trastornos. El método de la investigación es el trabajo de campo etnográfico. Los resultados muestran carencia de habilidades matemáticas específicamente en cálculo numérico; apreciándose desorden, combinación de operación simultáneamente entre adición y sustracción, déficit de atención durante la lectura de un problema por lo que no logran sistematizar, identificar los datos para las operaciones algorítmic

    Forward and hybrid path-integral methods in photoelectron holography: Sub-barrier corrections, initial sampling, and momentum mapping

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    We construct two strong-field path integral methods with full Coulomb distortion, in which the quantum pathways are mimicked by interfering electron orbits: the rate-based CQSFA (R-CQSFA) and the hybrid forward-boundary CQSFA (H-CQSFA). The methods have the same starting point as the standard Coulomb quantum-orbit strong-field approximation (CQSFA), but their implementation does not require preknowledge of the orbits' dynamics. These methods are applied to ultrafast photoelectron holography. In the rate-based method, electron orbits are forward propagated and we derive a nonadiabatic ionization rate from the CQSFA, which includes sub-barrier Coulomb corrections and is used to weight the initial orbit ensemble. In the H-CQSFA, the initial ensemble provides initial guesses for a subsequent boundary problem and serves to include or exclude specific momentum regions, but the ionization probabilities associated with individual trajectories are computed from sub-barrier complex integrals. We perform comparisons with the standard CQSFA and ab initio methods, which show that the standard, purely boundary-type implementation of the CQSFA leaves out whole sets of trajectories. We show that the sub-barrier Coulomb corrections broaden the resulting photoelectron momentum distributions (PMDs) and improve the agreement of the R-CQSFA with the H-CQSFA and other approaches. We probe different initial sampling distributions, uniform and otherwise, and their influence on the PMDs. We find that initial biased sampling emphasizes rescattering ridges and interference patterns in high-energy ranges, while an initial uniform sampling guarantees accurate modeling of the holographic patterns near the ionization threshold or polarization axis. Our results are explained using the initial to final momentum mapping for different types of interfering trajectories

    Schizotypy: The Way Ahead

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    Background: Empirical evidence suggests that schizotypy is a useful construct for analyzing and understanding psychotic disorders. However, several issues remain to be resolved. Method: This selective, critical review, addresses some questions and limitations, and discusses future directions of work. Results: First, we present a conceptual outline and discuss the evidence from translational and interdisciplinary studies on schizotypy. Next, we examine and discuss newer analytical and methodological approaches, including network and machine learning approaches. We also discuss newer psychometric identification approaches, such as those using biobehavioral and ambulatory assessment. Next, we review recent cross-cultural studies in schizotypy research. Finally, we identify new challenges and directions and draw conclusions. Conclusions: This selective, critical review suggests that new methods can contribute to the construction of a solid scientific model of schizotypy as a risk construct. // Esquizotipia: el Camino a Seguir. Antecedentes: la evidencia empírica ha demostrado que la esquizotipia es un constructo útil para analizar y comprender los trastornos psicóticos. Sin embargo, todavía quedan por resolver varias cuestiones. Método: en esta revisión selectiva y crítica se abordan algunas limitaciones, se discuten interrogantes y se comentan direcciones futuras de trabajo. Resultados: en primer lugar, se presenta una delimitación conceptual y se comenta la evidencia acumulada en diferentes estudios y niveles de análisis en el campo de la esquizotipia. A continuación, se examinan nuevos modelos psicopatológicos, como el modelo de red, y se presentan las diferentes herramientas desarrolladas y validadas para su evaluación. Seguidamente, se abordan algunas inquietudes metodológicas de fondo y se presentan nuevas técnicas y procedimientos psicométricos, como la evaluación ambulatoria y bioconductual. También se analizan algunos de los problemas inherentes en la investigación entre países y culturas. Finalmente, se establecen las conclusiones y se abordan nuevos desafíos y direcciones futuras de investigación. Conclusiones: esta revisión selectiva y crítica plantea que es necesario continuar trabajando en la construcción de un modelo científico sólido y refutable e incorporar nuevas pruebas científicas en el campo de la esquizotipia

    Target-Oriented Synthesis of Marine Coelenterazine Derivatives with Anticancer Activity by Applying the Heavy-Atom Effect

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    Photodynamic therapy (PDT) is an anticancer therapeutic modality with remarkable advantages over more conventional approaches. However, PDT is greatly limited by its dependence on external light sources. Given this, PDT would benefit from new systems capable of a light-free and intracellular photodynamic effect. Herein, we evaluated the heavy-atom effect as a strategy to provide anticancer activity to derivatives of coelenterazine, a chemiluminescent single-molecule widespread in marine organisms. Our results indicate that the use of the heavy-atom effect allows these molecules to generate readily available triplet states in a chemiluminescent reaction triggered by a cancer marker. Cytotoxicity assays in different cancer cell lines showed a heavy-atom-dependent anticancer activity, which increased in the substituent order of hydroxyl < chlorine < bromine. Furthermore, it was found that the magnitude of this anticancer activity is also dependent on the tumor type, being more relevant toward breast and prostate cancer. The compounds also showed moderate activity toward neuroblastoma, while showing limited activity toward colon cancer. In conclusion, the present results indicate that the application of the heavy-atom effect to marine coelenterazine could be a promising approach for the future development of new and optimized self-activating and tumor-selective sensitizers for light-free PDT

    Molecular identification of isolates of the Trichophyton mentagrophytes complex

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    Background: The Trichophyton mentagrophytes complex is the second most common causal agent of dermatophytosis. It comprises five species-T. mentagrophytes, T. interdigitale, T. erinacei, T quinckeanum, and T. benhamie, as well as nine different genotypes of T. mentagrophytes / T. interdigitale-which are morphologically similar; however, their susceptibility to antifungal agents may differ. For targeted therapy and better prognosis, it is important to identify these species at a molecular level. However, since many hospitals lack molecular methods, the actual aetiology of dermatophytosis caused by this complex remains unknown. Objective: To characterize 55 anthropophilic isolates of the T. mentagrophytes complex recovered from a dermatological centre in Yucatan, Mexico. Material and methods: Fifty-five isolates of the T. mentagrophytes complex were obtained from patients with tinea capitis, tinea pedis, tinea corporis, tinea barbae, and tinea unguium. They were characterized by their colonial and microscopic morphology on Sabouraud dextrose agar (SDA) and through the sequencing of a fragment from the region ITS1-5.8S-ITS2. Results: All colonies grown on SDA were white. Forty-six isolates formed colonies with a powdery texture, while nine isolates formed colonies with a velvety texture. The micromorphological features were typical of the T. mentagrophytes complex. The molecular analysis revealed that 55 isolates were microorganisms that belonged to the T. mentagrophytes complex, that 46 formed powdery colonies representing T. mentagrophytes, and that the other nine isolates that formed velvety colonies represented T. interdigitale. The latter nine isolates were obtained from patients with tinea pedis, tinea corporis, and tinea unguium. Conclusions: The colony morphology on SDA led to the identification of 46 isolates as T. mentagrophytes and nine isolates as T. interdigitale. At a molecular level, the species identified by their morphology were identified only as T. mentagrophytes complex

    Reasoning deficits among illicit drug users are associated with aspects of cannabis use

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    Background. Deficits in deductive reasoning have been observed among ecstasy/polydrug users. The present study seeks to investigate dose-related effects of specific drugs and whether these vary with the cognitive demands of the task. Methods. One hundred and five participants (mean age 21.33, S.D. 3.14; 77 females, 28 males) attempted to generate solutions for eight one-model syllogisms and one syllogism for which there was no valid conclusion (NVC). All of the one model syllogisms generated at least one valid conclusion and six generated two valid conclusions. In these six cases one of the conclusions was classified as common and the other as non-common. Results. The number of valid common inferences was negatively associated with aspects of short term cannabis use and with measures of IQ. The outcomes observed were more than simple post intoxication effects since cannabis use in the 10 days immediately before testing was unrelated to reasoning performance. Following adjustment for multiple comparisons, the number of non-common valid inferences was not significantly associated with any of the drug use measures. Conclusions. Recent cannabis use appears to impair the processes associated with generating valid common inferences while not affecting the production of non-common inferences. It is possible, therefore, that the two types of inference may recruit different executive resources which may differ in their susceptibility to cannabis-related effects

    Results of an Early Access Treatment Protocol of Daratumumab Monotherapy in Spanish Patients With Relapsed or Refractory Multiple Myeloma

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    Daratumumab is a human CD38-targeted monoclonal antibody approved as monotherapy for heavily pretreated relapsed and refractory multiple myeloma. We report findings for the Spanish cohort of an open-label treatment protocol that provided early access to daratumumab monotherapy and collected safety and patient-reported outcomes data for patients with relapsed or refractory multiple myeloma. At 15 centers across Spain, intravenous daratumumab (16 mg/kg) was administered to 73 patients who had >= 3 prior lines of therapy, including a proteasome inhibitor and an immunomodulatory drug, or who were double refractory to both. The median duration of daratumumab treatment was 3.3 (range: 0.03-13.17) months, with a median number of 12 (range: 1-25) infusions. Grade 3/4 treatment-emergent adverse events were reported in 74% of patients and included lymphopenia (28.8%), thrombocytopenia (27.4%), neutropenia (21.9%), leukopenia (19.2%), and anemia (15.1%). Common (>5%) serious treatmentemergent adverse events included respiratory tract infection (9.6%), general physical health deterioration (6.8%), and back pain (5.5%). Infusion-related reactions occurred in 45% of patients. The median change from baseline in all domains of the EQ-5D-5L and EORTC QLQ-C30 was mostly 0. A total of 18 (24.7%) patients achieved a partial response or better, with 10 (13.7%) patients achieving a very good partial response or better. Median progression-free survival was 3.98 months. The results of this early access treatment protocol are consistent with previously reported trials of daratumumab monotherapy and confirm its safety and antitumoral efficacy in Spanish patients with heavily treated relapsed or refractory multiple myeloma
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