Simón Bolívar University

About: Simón Bolívar University is a education organization based out in Caracas, Venezuela. It is known for research contribution in the topics: Population & Crystallization. The organization has 5912 authors who have published 8294 publications receiving 126152 citations.

Detection of seizure precursors from depth-EEG using a sign periodogram transform

Abstract: Brief bursts of focal, low amplitude rhythmic activity have been observed on depth electroencephalogram (EEG) in the minutes before electrographic onset of seizures in human mesial temporal lobe epilepsy. We have found these periods to contain discrete, individualized synchronized activity in patient-specific frequency bands ranging from 20 to 40 Hz. We present a method for detecting and displaying these events using a periodogram of the sign-limited temporal derivative of the EEG signal, denoted joint sign periodogram event characterization transform (JSPECT). When applied to continuous 2-6 day depth-EEG recordings from ten patients with temporal lobe epilepsy, JSPECT demonstrated that these patient-specific EEG events reliably occurred 5-80 s prior to electrical onset of seizures in five patients with focal, unilateral seizure onsets. JSPECT did not reveal this type of activity prior to seizures in five other patients with bilateral, extratemporal or more diffuse seizure onsets on EEG. Patient-specific, localized rhythmic events may play an important role in seizure generation in temporal lobe epilepsy. The JSPECT method efficiently detects these events, and may be useful as part of an automated system for predicting electrical seizure onset in appropriate patients.

Four-jet production at the Large Hadron Collider at next-to-leading order in QCD.

Abstract: We present the cross sections for production of up to four jets at the Large Hadron Collider, at next-to-leading order in the QCD coupling. We use the BlackHat library in conjunction with SHERPA and a recently developed algorithm for assembling primitive amplitudes into color-dressed amplitudes. We adopt the cuts used by ATLAS in their study of multijet events in $pp$ collisions at $\sqrt{s}=7\text{ }\text{ }\mathrm{TeV}$. We include estimates of nonperturbative corrections and compare to ATLAS data. We store intermediate results in a framework that allows the inexpensive computation of additional results for different choices of scale or parton distributions.

Kinetic analysis of the iron oxide reduction using hydrogen-carbon monoxide mixtures as reducing agent

Abstract: The kinetics of the reduction of hematite pellets using hydrogen-carbon monoxide mixtures as reducing agent was described by using the "grain model". This model involves the particle size and the porosity of the pellet asmain structural parameters which affect directly the kinetics of the hematite pellets during the reduction process. The predictions of the model were compared with the experimental results. Fired hematite pellets were reduced at 850°C using hydrogen, carbon monoxide and Midrex gas. The weight loss technique was used to follow the reduction process. The reduction of iron oxide pellets using hydrogen or carbon monoxide is a mixed controlled system, where chemical reaction and internal gas diffusion are competing processes during the first stage of the reduction, while internal gas diffusion becomes controlling step at the last stage of the process. The reduction of iron oxide pellets using Midrex gas is a mixed controlled system throughout the whole reduction process.

IceCube — the next generation neutrino telescope at the South Pole

Abstract: IceCube is a large neutrino telescope of the next generation to be constructed in the Antarctic Ice Sheet near theSouth Pole. We present the conceptual design and the sensitivity of the IceCube detector to predicted fluxes of neutrinos, both atmospheric and extra-terrestrial. A complete simulation of the detector design has been used to study the detector's capability to search for neutrinos from sources such as active galaxies, and gamma-ray bursts.

Pancreatic Beta Cell Death: Novel Potential Mechanisms in Diabetes Therapy.

Abstract: Purpose of Review. Describing the diverse molecular mechanisms (particularly immunological) involved in the death of the pancreatic beta cell in type 1 and type 2 diabetes mellitus. Recent Findings. Beta cell death is the final event in a series of mechanisms that, up to date, have not been entirely clarified; it represents the pathophysiological mechanism in the natural history of diabetes mellitus. These mechanisms are not limited to an apoptotic process only, which is characteristic of the immune-mediated insulitis in type 1 diabetes mellitus. They also include the action of proinflammatory cytokines, the production of reactive oxygen species, DNA fragmentation (typical of necroptosis in type 1 diabetic patients), excessive production of islet amyloid polypeptide with the consequent endoplasmic reticulum stress, disruption in autophagy mechanisms, and protein complex formation, such as the inflammasome, capable of increasing oxidative stress produced by mitochondrial damage. Summary. Necroptosis, autophagy, and pyroptosis are molecular mechanisms that modulate the survival of the pancreatic beta cell, demonstrating the importance of the immune system in glucolipotoxicity processes and the potential role for immunometabolism as another component of what once known as the “ominous octet.”