University of Los Andes

About: University of Los Andes is a education organization based out in Bogotá, Colombia. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 17616 authors who have published 25555 publications receiving 413463 citations.

Search for low mass vector resonances decaying into quark-antiquark pairs in proton-proton collisions at $ \sqrt{s}=13 $ TeV

Abstract: A search for narrow vector resonances decaying into quark-antiquark pairs is presented The analysis is based on data collected in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 359 fb−1 The hypothetical resonance is produced with sufficiently high transverse momentum that its decay products are merged into a single jet with two-prong substructure A signal would be identified as a peak over a smoothly falling background in the distribution of the invariant mass of the jet, using novel jet substructure techniques No evidence for such a resonance is observed within the mass range of 50-300 GeV Upper limits at 95% confidence level are set on the production cross section, and presented in a mass-coupling parameter space The limits further constrain simplified models of dark matter production involving a mediator interacting between quarks and dark matter particles through a vector or axial-vector current In the framework of these models, the results are the most sensitive to date, extending for the first time the search region to masses below 100 GeV

Epidemiology and pathophysiology of neurogenic bladder after spinal cord injury

Abstract: Spinal cord injury (SCI) usually affects younger age groups with male preponderance. The most common traumatic cause is road traffic accident followed by sports accidents and gun-shot injuries. Infections and vascular events make up non-traumatic causes. There is regional variance in incidence and prevalence of SCI. Most systematic reviews have been undertaken from USA, Canada, and Australia with only few from Asia with resultant difficulty in estimation of worldwide figures. Overall, the incidence varies from 12 to more than 65 cases/million per year. The first peak is in young men between 15 and 29 years and second peak in older adults. The average age at injury is 40 years, with commonest injury being incomplete tetraplegia followed by complete paraplegia, complete tetraplegia, and incomplete paraplegia. The bladder function is reliant on both central and peripheral nervous systems for co-ordination of storage and voiding phases. The pathophysiology of bladder dysfunction can be described as an alteration in micturition reflex. It is postulated that a new spinal reflex circuit develops which is mediated by C fibers as response to reorganization of synaptic connections in spinal cord. This is responsible for the development of neurogenic detrusor overactivity (NDO). Various neurotrophic hormones like nerve growth factor affect the morphological and physiological changes of the bladder afferent neurons leading to neuropathic bladder dysfunction. A suprasacral SCI usually results in a voiding pattern consistent with NDO and sphincter dyssynergia. Injury to either the sacral cord or cauda equina results in detrusor hypoactivity/areflexia with sphincter weakness.

Evidence of b -jet quenching in PbPb collisions at sNN =2.76TeV

Abstract: The production of jets associated to bottom quarks is measured for the first time in PbPb collisions at a center-of-mass energy of 2.76 TeV per nucleon pair. Jet spectra are reported in the transverse momentum (pt) range of 80-250 GeV, and within pseudorapidity abs(eta < 2). The nuclear modification factor (R[AA]) calculated from these spectra shows a strong suppression in the b-jet yield in PbPb collisions relative to the yield observed in pp collisions at the same energy. The suppression persists to the largest values of pt studied, and is centrality dependent. The R[AA] is about 0.4 in the most central events, similar to previous observations for inclusive jets. This implies that jet quenching does not have a strong dependence on parton mass and flavor in the jet pt range studied.