Transport in random quantum dot superlattices

We present a novel model to calculate single-electron states in random quantum dot superlattices made of wide-gap semiconductors. The source of disorder comes from the random arrangement of the quantum dots (configurational disorder) as well as spatial inhomogeneities of their shape (morphological disorder). Both types of disorder break translational symmetry and prevent the formation of minibands, as occurs in regimented arrays of quantum dots. The model correctly describes channel mixing and broadening of allowed energy bands due to elastic scattering by disorder

Oral heparin: status review

Unfractionated heparin and low molecular weight heparin are the most commonly used antithrombotic and thromboprophylactic agents in hospital practice. Extended out-of-hospital treatment is inconvenient in that these agents must be administered parenterally. Current research is directed at development of a safe and effective oral antithrombotic agent as an alternative for the effective, yet difficult to use vitamin K antagonists. A novel drug delivery technology that facilitates transport of drugs across the gastrointestinal epithelium has been harnessed to develop an oral dosage form of unfractionated heparin. Combining unfractionated heparin with the carrier molecule, sodium N-(8 [2-hydroxybenzoyl]amino) caprylate, or SNAC has markedly increased the gastrointestinal absorption of this drug. Preclinical and clinical studies to-date suggests that oral heparin-SNAC can confer a clinical efficacious effect; further confirmation is sought in planned clinical trials

X-ray emission from stellar jets by collision against high-density molecular clouds: an application to HH 248

We investigate the plausibility of detecting X-ray emission from a stellar jet that impacts against a dense molecular cloud. This scenario may be usual for classical T Tauri stars with jets in dense star-forming complexes. We first model the impact of a jet against a dense cloud by 2D axisymmetric hydrodynamic simulations, exploring different configurations of the ambient environment. Then, we compare our results with XMM-Newton observations of the Herbig-Haro object HH 248, where extended X-ray emission aligned with the optical knots is detected at the edge of the nearby IC 434 cloud. Our simulations show that a jet can produce plasma with temperatures up to 10 MK, consistent with production of X-ray emission, after impacting a dense cloud. We find that jets denser than the ambient medium but less dense than the cloud produce detectable X-ray emission only at the impact onto the cloud. From the exploration of the model parameter space, we constrain the physical conditions (jet density and velocity, cloud density) that reproduce well the intrinsic luminosity and emission measure of the X-ray source possibly associated with HH 248. Thus, we suggest that the extended X-ray source close to HH 248 corresponds to the jet impacting on a dense cloud.Comment: Accepted for publication in ApJ. (12 pages, 12 figures

Modificación de la composición de la flora en bordes de bosques fragmentados de Austrocedrus chilensis en Patagonia

Austrocedrus chilensis es una de las especies arbóreas nativas del bosque andino patagónico más afectadas por el proceso de fragmentación, originando bosquetes remanentes rodeados de pasturas. Estudiamos la vegetación en bordes de A. chilensis adyacentes a áreas cortadas 10 años atrás, con especial referencia a la regeneración de A. chilensis, diversidad, abundancia y distribución especifica. Se encontró que la composición original de la vegetación fue fuertemente modificada, con una alta proporción de especies herbáceas exóticas en la zona de borde. La diversidad y la abundancia de especies leñosas fueron mayores en el interior del bosque (p = 0.0289yp= 0.0149), lo mismo que la riqueza de especies nativas (p = 0.0053) y la regeneración de A. chilensis (p = 0.0408), en tanto que la abundancia de especies herbáceas fue mayor en el borde (p = 0.0197). Durante los primeros 10 años de la sucesión posterior al disturbio, la tendencia de los bosquetes de A. chilensis remanentes es la retracción.In the Patagonian Andes of Argentina, Austrocedrus chilensis is one of the native tree species most affected by forest fragmentation, resulting in remnants stands surrounded by grasslands. We studied vegetation in the edges of stands of dense A. chilensis adjoining areas that were cut 10 years earlier, with special reference to A. chilensis regeneration, diversity, abundance and specific species distribution. We found that the original composition of the vegetation had been strongly modified, there was a high proportion of exotic herbaceous species in the edge. Diversity and abundance of woody species was superior in the core forest (p = 0.0289 and p = 0.0149), and so was the richness of native species (p = 0.0053) and regeneration of A. chilensis (p = 0.0408). On the other hand the abundance of herbaceous species was greater in the edge (p = 0.0197). During the first years of the succession, the forest in the edge area tends to retract.Fil: Carabelli, Francisco Andrés Carabelli. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Centro de Investigación y Extensión Forestal Andino Patagónico; ArgentinaFil: Orellana Ibáñez, Ivonne Alejandra. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Centro de Investigación y Extensión Forestal Andino Patagónico; ArgentinaFil: Jaramillo, Marcelo M.. Centro de Investigación y Extensión Forestal Andino Patagónico; ArgentinaFil: Gomez, Mariano Facundo. Centro de Investigación y Extensión Forestal Andino Patagónico; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentin

A Small Non-Coding RNA Modulates Expression of Pilus-1 Type in Streptococcus pneumoniae

Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide, and about 30% of the pneumococcal clinical isolates show type I pili-like structures. These long proteinaceous polymers extending from the bacterial surface are encoded by pilus islet 1 and play major roles in adhesion and host colonization. Pili expression is bistable and is controlled by the transcriptional activator RlrA. In this work, we demonstrate that the previously identified small noncoding RNA srn135 also participates in pilus regulation. Our findings show that srn135 is generated upon processing of the 5'-UTR region of rrgA messenger and its deletion prevents the synthesis of RrgA, the main pili adhesin. Moreover, overexpression of srn135 increases the expression of all pili genes and rises the percentage of piliated bacteria within a clonal population. This regulation is mediated by the stabilization of rlrA mRNA since higher levels of srn135 increase its half-life to 165%. Our findings suggest that srn135 has a dual role in pilus expression acting both in cis- (on the RrgA levels) and in trans- (modulating the levels of RlrA) and contributes to the delicate balance between pili expressing and non-expressing bacteria.This research was funded by Fondo de Investigación Sanitaria (FIS), grant number PI11/00656, and Ministerio de Economía, Industria y Competitividad, grant number BIO2017-82951-R.” P.A. was the recipient of a contract funded by the FIS project PI11/00656 and A.G.-S. was the recipient of a contract funded by Instituto de Salud Carlos III (CA10/1103).S

Diaphragmatic paralysis, respiratory function, and postoperative pain after interscalene brachial plexus block with a reduced dose of 10 ml levobupivacaine 0.25% versus a 20 ml dose in patients undergoing arthroscopic shoulder surgery: study protocol for the randomized controlled double-blind Redole

Background: Arthroscopic shoulder surgery causes severe postoperative pain. An interscalene brachial plexus block provides adequate analgesia, but unintended spread of the local anesthetic administered may result in a phrenic nerve block, usually associated with a nonnegligible incidence of acute hemidiaphragmatic paralysis. The main purpose of this trial will be to analyze the incidence of hemidiaphragmatic paralysis ensuing after interscalene brachial plexus block in patients undergoing arthroscopic shoulder surgery administered a standard volume (20 ml) vs. a low volume (10 ml) of levobupivacaine 0.25%. Methods: This will be a prospective double-blind randomized controlled single-center two-arm comparative trial. Forty-eight patients will be included. The primary goal will be to ultrasonographically determine the incidence of hemidiaphragmatic paralysis by calculating the diaphragmatic thickness ratio in each group. The secondary goals will be to compare the two arms in terms of (1) decrease in forced vital capacity and (2) in forced expiratory volume at 1 s by spirometry; (3) decrease in diaphragmatic excursion by ultrasound; (4) 24-h total intravenous morphine consumption; (5) time to first opioid request of a patient-controlled analgesia pump; and (6) postoperative complications. Discussion: This trial will demonstrate that a low-volume interscalene brachial plexus block decreases hemidiaphragmatic paralysis following arthroscopic shoulder surgery according to spirometry and ultrasound measurements and does not provide inferior postoperative analgesia to the standard volume, as measured by opioid requirements. Trial registration: EudraCT and Spanish Trial Register (REec) registration number: 2019-003855-12 (registered on 7 January 2020). ClinicalTrials.gov identification number: NCT04385966 (retrospectively registered on 8 May 2020). Ethics Committee approval: EC19/093 (18 December 2019)

The essentials of online education and the use of digital tools

The implementation of tools in the educational system has inspired the teachinglearning methods of foreign languages to develop new ways of motivating pupils. This report determines the importance of Learning Management Systems, as well as the use of Moodle in the community of teachers and students at the University of El Salvador. Besides, the most essential tools for educational purposes in virtual environments are presented: Nearpod, Padlet, Kahoot, Flippity, Flipgrid, Edpuzzle, Powtoon, and Life Worksheet. Also, the following programs for the design of didactic materials for online classes are discussed: Audacity, Genially, Google presentations, Open Shot and Google Sites. The course entitled: The Administration of Virtual Environments for Teaching and Learning Foreign Languages is explained with its objectives, and some of the achievements, as well as recommendations, are included to be considered in the design of new courses. Keywords: Teaching-learning method ; Online tolos ; LMS, Moodle ; ICTs ; Online resources ; Interactive learning