289 research outputs found
Bancarizing with credit cards: Experimental evidence on interest rates and minimum payments elasticities for new clients
We study the bancarization of marginal borrowers using credit cards and document that this process is difficult: default risk is substantial, returns heterogeneous, and account closings common. We also take advantage of a randomized control trial that varied interest rates and minimum payments in a very wide range. Against our hypothesis, we find that default risk is very insensitive to (randomized) large changes in interest rates and minimum payments. This could imply that regulating these contract terms may not necessarily "protect" consumers against default and that moral hazard in this market is negligible on average
Patent Foramen Ovale in Cerebral Infarction
Recent studies support the hypothesis of a close aetiological and pathogenic association between the presence of patent foramen ovale (PFO) and cryptogenic stroke. The therapeutic options currently used in the treatment of these patients range from standard antiaggregation and standard-dose anticoagulation to the percutaneous occlusion of the PFO. The use or recommendation of treatment is based both on clinical risk factors associated with PFO, such as age, detection of states of hypercoagulability and previous history of stroke, and on the risks associated to right-to-left shunt (RLSh) and PFO, such as the size of PFO, magnitude of RLSh and the presence of atrial septal aneurysm (ASA). However, there is currently no consensus regarding the most suitable treatment and it is surprising to observe the widespread use of certain therapeutic approaches which are not supported by clinical evidence
Graft copolymers of ethyl methacrylate on waxy maize starch derivatives as novel excipients for matrix tablets: Drug release and fronts movement kinetics
A previous paper [1] deals with the physicochemical and technological characterization of novel graft copolymers of ethyl methacrylate (EMA) on waxy maize starch (MS) and hydroxypropylstarch (MHS). The results obtained suggested the potential application of these copolymers as excipients for compressed non-disintegrating matrix tablets. Therefore, the purpose of the present study was to investigate the mechanism governing drug release from matrix systems prepared with the new copolymers and anhydrous theophylline or diltiazem HCl as model drugs with different solubility. The influence of the carbohydrate nature, drying procedure and initial pore network on drug release kinetics was also evaluated. Drug release experiments were performed from free tablets. Radial drug release and fronts movement kinetics were also analysed, and several mathematical models were employed to ascertain the drug release mechanisms. The drug release markedly depends on the drug solubility and the carbohydrate nature but is practically not affected by the drying process and the initial matrix porosity. A faster drug release is observed for matrices containing diltiazem HCl compared with those containing anhydrous theophylline, in accordance with the higher drug solubility and the higher friability of diltiazem matrices. In fact, although diffusion is the prevailing drug release mechanism for all matrices, the erosion mechanism seems to have some contribution in several formulations containing diltiazem. A reduction in the surface exposed to the dissolution medium (radial release studies) leads to a decrease in the drug release rate, but the release mechanism is not essentially modified. The nearly constant erosion front movement confirms the behaviour of these systems as inert matrices where the drugs are released mainly by diffusion through the porous structure.Ministerio de Educación y Ciencia MAT2004-0159
Using radio astronomical receivers for molecular spectroscopic characterization in astrochemical laboratory simulations: A proof of concept
We present a proof of concept on the coupling of radio astronomical receivers
and spectrometers with chemical reactorsand the performances of the resulting
setup for spectroscopy and chemical simulations in laboratory astrophysics.
Several experiments including cold plasma generation and UV photochemistry were
performed in a 40\,cm long gas cell placed in the beam path of the Aries 40\,m
radio telescope receivers operating in the 41-49 GHz frequency range interfaced
with fast Fourier transform spectrometers providing 2 GHz bandwidth and 38 kHz
resolution.
The impedance matching of the cell windows has been studied using different
materials. The choice of the material and its thickness was critical to obtain
a sensitivity identical to that of standard radio astronomical observations.
Spectroscopic signals arising from very low partial pressures of CH3OH,
CH3CH2OH, HCOOH, OCS,CS, SO2 (<1E-03 mbar) were detected in a few seconds. Fast
data acquisition was achieved allowing for kinetic measurements in
fragmentation experiments using electron impact or UV irradiation. Time
evolution of chemical reactions involving OCS, O2 and CS2 was also observed
demonstrating that reactive species, such as CS, can be maintained with high
abundance in the gas phase during these experiments.Comment: Accepted for publication in Astronomy and Astrophysics in September
21, 2017. 16 pages, 18 figure
Activación conductual para el tratamiento de la depresión resistente al tratamiento: modelo teórico y protocolo de intervención (AC-DRT)
Background: Treatment-resistant depression (TRD) is a severe public health problem and a condition uncommonly addressed by psychological therapies. This paper presents a theoretical model, grounded in established learning principles and in the perspective of behavioral activation (BA), to explain its constitution and development. Method: A review of theoretical models and empirical research on TRD was conducted in major databases. Results: The model reflects how patients with TRD are more susceptible to becoming trapped in their condition by seeking to avoid discomfort through avoidance and escape behaviors, which increasingly drives them away from sources of positive reinforcement. Based on this model, a BA-based intervention protocol is suggested for the treatment of TRD. Through six phases (in a total of thirteen sessions), the protocol guides the intervention towards the reestablishment of personalized routines to increase the probability of reinforcement and reduce avoidance behaviors. Conclusions: Although the model holds significant potential to become an effective intervention in TRD, future research will allow the evaluation of the efficacy of the protocol as a standalone intervention.Antecedentes: La depresión resistente al tratamiento (DRT) constituye un severo problema de salud pública y es una condición poco abordada por las terapias psicológicas. En este artículo se presenta un modelo teórico, fundamentado en contrastados principios de aprendizaje y en el modelo de activación conductual (AC) para explicar su constitución y desarrollo. Método: Una revisión de los modelos teóricos y una investigación empírica de la depresión resistente al tratamiento se llevó a cabo a través de las principales bases de datos. Resultados: El modelo refleja cómo los pacientes con DRT son más propensos a quedar atrapados en su estado al procurar evitar el malestar por medio de comportamientos de evitación y escape, lo que les aleja cada vez más de las fuentes de reforzamiento positivo. A partir de este modelo se propone un protocolo de intervención basado en la AC para el tratamiento de la DRT. A través de seis fases (en un total de trece sesiones) el protocolo orienta la intervención hacia el restablecimiento de rutinas personalizadas para aumentar la probabilidad del refuerzo y reducir los comportamientos de evitación. Conclusiones: Aunque este modelo cuenta con un potencial significativo de llegar a ser una intervención eficaz en el tratamiento de la depresión resistente al tratamiento, la investigación futura permitirá medir la eficacia del protocolo como intervención única
Monitoring workload and performance response to taekwondo training
This study compared the association between Foster’s and Banister’s TRIMP methods for quantifying
internal training load and training stimuli responses. Methods: A group of twenty-two Taekwondo competitors were
divided by gender and level of expertise. The athletes practiced three different types of exercises to develop the
following skills: a) speed, b) power, and c) aerobic power. Results: A significant correlation was obtained between the
Foster’s and Banister’s TRIMP methods for developing aerobic capacity (r = 0.60, p = 0.004) and power (r = 0.52, p =
0.014). No significant correlation was suggested between training methods and speed training (r = 0.20, p = 0.377).
Conclusion: Lactate and heart rate responses to different types of exercises suggested the need for aerobic and
anaerobic-based training sessions. The use of rating of perceived exertion scale-based measurements to monitor
workload is recommended for Taekwondo competitors
Raman Fingerprint of Pressure-Induced Phase Transitions in TiS3Nanoribbons: Implications for Thermal Measurements under Extreme Stress Conditions
Two-dimensional layered trichalcogenide materials have recently attracted the attention of the scientific community because of their robust mechanical and thermal properties and applications in opto- and nanoelectronics devices. We report the pressure dependence of out-of-plane Ag Raman modes in high quality few-layer titanium trisulfide (TiS3) nanoribbons grown using a direct solid-gas reaction method and infer their cross-plane thermal expansion coefficient. Both mechanical stability and thermal properties of the TiS3 nanoribbons are elucidated by using phonon-spectrum analyses. Raman spectroscopic studies at high pressure (up to 34 GPa) using a diamond anvil cell identify four prominent Ag Raman bands; a band at 557 cm-1 softens under compression, and others at 175, 300, and 370 cm-1 show normal hardening. Anomalies in phonon mode frequencies and excessive broadening in line width of the soft phonon about 13 GPa are attributed to the possible onset of a reversible structural transition. A complete structural phase transition at 43 GPa is inferred from the Ag soft mode frequency (557 cm-1) versus pressure extrapolation curve, consistent with recently reported theoretical predictions. Using the experimental mode Grüneisen parameters γi of Raman modes, we estimated the cross-plane thermal expansion coefficient Cv of the TiS3 nanoribbons at ambient phase to be 1.321 × 10-6 K-1. The observed results are expected to be useful in calibration and performance of next-generation nanoelectronics and optical devices under extreme stress condition
Magnetobiochronology of lower Pliocene marine sediments from the lower Guadalquivir Basin: insights into the tectonic evolution of the Strait of Gibraltar area
The Gibraltar Arc is a complex tectonic region, and several competing models have been proposed to explain its evolution. We studied the sedimentary fill of the Guadalquivir Basin to identify tectonic processes that were occurring when the reopening of the Strait of Gibraltar led to the reestablishment of Mediterranean outflow. We present a chronostratigraphic framework for the Lower Pliocene sediments from the lower Guadalquivir Basin (SW Spain). The updated chronology is based on magnetobiostratigraphic data from several boreholes. Our results show that the studied interval in the La Matilla core is in the early Pliocene section, providing better constraints on the sedimentary evolution of the basin during that period. Migrating depositional facies led to a younger onset of sandy deposition basinward. At the northwestern passive margin, a 0.7 m.y. period of sedimentary bypass related to a sharp decrease in sedimentation rates and lower sea levels resulted from the tectonic uplift of the forebulge. In contrast, high sedimentation rates with continuous deep-marine sedimentation are recorded at the basin center due to continuous tectonic subsidence and west-southwestward progradation of axial depositional systems. The marginal forebulge uplift, continuous tectonic basinal subsidence, and southward progradation of clinoforms in the early Pliocene can be explained by the pull of a lithospheric slab beneath the Gibraltar Arc as the Strait of Gibraltar opened. These findings are, to our knowledge, the first reported sedimentary expression of slab pull beneath the Betics related to the opening of the Strait of Gibraltar after the Messinian salinity crisis
¿Va a cambiar la neurología tras la pandemia de COVID-19 en los próximos 5 años?: estudio de enfoque mediante informadores clave
Review[Abstract] Introduction. The COVID-19 pandemic will give rise to long-term changes in neurological care, which are not easily predictable.
Material and methods. A key informant survey was used to enquire about the changes expected in the specialty over the next 5 years. The survey was completed by heads of neurology departments with broad knowledge of the situation, having been active during the pandemic.
Results. Despite a low level of consensus between participants, there was strong (85%) and moderate consensus (70%) about certain subjects, mainly the increase in precautions to be taken, the use of telemedicine and teleconsultations, the reduction of care provided in in-person consultations to avoid the presence of large numbers of people in waiting rooms, the development of remote training solutions, and the changes in monitoring visits during clinical trials. There was consensus that there would be no changes to the indication of complementary testing or neurological examination.
Conclusion. The key informant survey identified the foreseeable changes in neurological care after the pandemic.[Resumen] Introducción. La pandemia de COVID-19 va a conllevar cambios en la asistencia neurológica, que no se pueden prever fácilmente a largo plazo.
Material y métodos. A través de un modelo de informadores clave se busca el consenso de cómo va a ser la especialidad en un plazo de 5 años, siendo los encuestados jefes de servicio de neurología con conocimiento amplio de la situación al haber actuado durante la pandemia.
Resultados. Aunque se obtiene un grado de acuerdo bajo entre los encuestados, sí se describen acuerdos por consenso a nivel mayor (85%) y menor (70%). Los principales acuerdos se refieren al incremento de precauciones, al uso de la telemedicina, al mantenimiento de las consultas telefónicas, a la reducción de asistencia a las consultas evitando que hayan salas de espera con un número alto de personas, al desarrollo de técnicas docentes no presenciales y a la adaptación en el desarrollo de ensayos clínicos en relación con la visita de los monitores. Sin embargo, no se acuerda que haya cambios en la indicación de exploraciones complementarias, ni en la propia exploración neurológica.
Conclusión. El método de informadores clave ha permitido conocer qué cambios se pueden prever tras la pandemia
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