Simulación Desarrollada En Simulink De Un Sistema Mecanico Masa-Resorte-Amortiguador Con Fuerza Externa Variable

This research is about the simulation of a mechanical system consisting of a mass, a spring, a shock absorber and the application of an external force, allows to understand the analytical and numerical behavior of the differential equation that governs said event. In this analysis the differential equation is obtained and solved analytically and numerically, for the numerical solution Simulink was used, since this allows the design and simulation of a system of textual and graphic form, which are fundamental elements for programming and operation of a system. This research is about the simulation of a mechanical system consisting of a mass, a spring, a shock absorber and the application of an external force, allows to understand the analytical and numerical behavior of the differential equation that governs said event. In this analysis the differential equation is obtained and solved analytically and numerically, for the numerical solution Simulink was used, since this allows the design and simulation of a system of textual and graphic form, which are fundamental elements for programming and operation of a system.

Anesthetic Management of Patients with Post COVID-19 Syndrome: A Quality Improvement Project

Background: Millions of people have been infected with the novel Coronavirus 2019, creating a global pandemic. Despite the high mortality rate of this viral infection, millions of people have recovered, and are now presenting for surgical procedures with a history of COVID-19 infection. Residual effects of COVID-19 infection have been observed for several after diagnosis and are referred to as post COVID-19 syndrome. Post COVID-19 sequela can alter multisystem physiological processes that may alter anesthetic care throughout the perioperative period. Objectives: The purpose of this quality improvement project is to improve anesthesia provider knowledge on the management of patients who have post COVID-19 syndrome. Methods: The primary methodology of the proposed quality improvement project is to administer an educational intervention to anesthesia providers which discusses the management of patients undergoing elective surgery and have a history of COVID-19 infection. Pre- and post- assessment surveys will be used to measure the effectiveness of the educational intervention. Results: Overall, there was an improvement in anesthesia provider knowledge following the educational intervention. Participants also answered they would “always” or “often” consider additional pre-operative testing compared to “sometimes” prior to the educational intervention

Editorial

"What we know is a drop; What we ignore is the ocean "Isaac NewtonThis time we open this edition of MATUA magazine with this one with this small but forceful phrase, from one of the greatest parents of all time, that reminds us that there is not much to find in this immense sea of knowledge that are the sciences This edition the magazine counts on authors of diverse countries like Venezuela, Ecuador and Colombia. Expert researchers in various branches of mathematics. Mathematical application, for example, Optimization of reference functions through optimization based on binary biogeography. Pure mathematics topics such as the construction of matrices of calculation of rank M, some inequalities of Hermite-Hadamard type for functions whose second derivative is convex generalized. Studies of great interest in educational mathematics such as the use of Geogebra as a tool as a dynamizing tool for the teaching-learning process of area and volume of regular polyhedra, as well as other technological resources in the teaching of mathematics.These are some of the topics that MATUA magazine has brought in this edition to delight them and to continue persevering in the path of research.We thank the editorial board and the scientist of the journal, the Vice-Rector for Research of the Universidad del Atlántico for their unconditional support, however, this publication has not been able to be carried out. Also to all the evaluating researchers who collaborate with their timely, efficient and quality reviews. We hope this publication of the taste of each of the people who day and day live this beautiful path called mathematics. 

Editorial

“La vida es buena por solo dos cosas, descubrir y enseñar las matemáticas.                                                                                                Simeon Poisson Esta frase es un pilar en el deber ser de la revista MATUA y de quienes viven el camino de las ciencias. Día a día hacemos realidad esta frase, con cada segundo que pasa, la vida misma nos muestra y nos enseña nuevos caminos, nuevas formas de hacer las cosas, nuevas cosas por hacer, es deber de cada científico enseñarle al resto las cosas descubiertas.En esta edición la revista MATUA cuenta con autores de diversos países como Venezuela, Costa rica y Colombia. Investigadores expertos en matemática educativa, aplicada y pura. En matemática aplicada, por ejemplo, Se analizan situaciones cotidianas como una medición de la pobreza. Temas de matemática educativa como la formación docente en Venezuela. Temas de matemática pura como el análisis de algunas soluciones de ecuaciones diferenciales de orden dos. Estos son algunos de los temas que la revista MATUA ha traído en esta edición para deleitarlos y seguir en este camino de descubrir y enseñar.Agradecemos al comité editorial y científico de la revista, la Vicerrectoría de investigaciones de la Universidad del Atlántico por su incondicional apoyo sin el cual no se hubiera podido llevar a cabo esta publicación. También a todos los investigadores evaluadores que nos colaboraron con sus revisiones oportunas, eficientes y de calidad. Esperamos disfruten esta publicación y que sirva para el fortalecimiento y crecimiento de este universo llamado matemática

Insulin resistance in lean and overweight non-diabetic Caucasian adults: Study of its relationship with liver triglyceride content, waist circumference and BMI

Insulin resistance is the pathophysiological precursor of type 2 diabetes mellitus (DM-2), and its relationship with non-alcoholic fatty liver disease (NAFLD) has been widely studied in patients with obesity or metabolic syndrome using not only ultrasound but also liver biopsies or proton magnetic resonance spectroscopy (H1-MRS) to assess liver fat content. In contrast, there are no studies on insulin resistance and NAFLD in lean or overweight Caucasian individuals using H1-MRS or liver biopsies for the quantification of hepatic triglyceride content. Our objectives were to study the presence of insulin resistance in lean and overweight Caucasian adults and investigate its possible relationship with liver triglyceride content, waist circumference (as proxy of visceral adiposity), BMI, and cardiometabolic risk factors.A cross-sectional study was conducted in 113 non-obese, non-diabetic individuals classified as overweight (BMI 25–29.9 kg/m2) or lean (BMI 19.5–24.9 kg/m2). Hepatic triglyceride content was quantified by 3T H1-MRS. NAFLD was defined as hepatic triglyceride content >5.56%. Insulin resistance (HOMA-IR), serum adiponectin, and tumor necrosis factor (TNF) were determined.HOMA-IR was significantly correlated with hepatic triglyceride content (r:0.76; p<0.0001). The lean-with-NAFLD group had significantly higher HOMA-IR (p<0.001) and lower serum adiponectin (p<0.05) than the overweight-without-NAFLD group. Insulin resistance was independently associated with NAFLD but not with waist circumference or BMI. Regression analysis showed hepatic triglyceride content to be the most important determinant of insulin resistance (p<0.01).Our findings suggest that NAFLD, once established, seems to be involved in insulin resistance and cardio-metabolic risk factors above and beyond waist circumference and BMI in non-obese, non-diabetic Caucasian individuals

Predictors of mortality in HIV-associated hospitalizations in Portugal: a hierarchical survival model

<p>Abstract</p> <p>Background</p> <p>The beneficial effects of highly active antiretroviral therapy, increasing survival and the prevention of AIDS defining illness development are well established. However, the annual Portuguese hospital mortality is still higher than expected. It is crucial to understand the hospitalization behaviour to better allocate resources. This study investigates the predictors of mortality in HIV associated hospitalizations in Portugal through a hierarchical survival model.</p> <p>Methods</p> <p>The study population consists of 12,078 adult discharges from patients with HIV infection diagnosis attended at Portuguese hospitals from 2005–2007 that were registered on the diagnosis-related groups' database.</p> <p>We used discharge and hospital level variables to develop a hierarchical model. The discharge level variables were: age, gender, type of admission, type of diagnoses-related group, related HIV complication, the region of the patient's residence, the number of diagnoses and procedures, the Euclidean distance from hospital to the centroid of the patient's ward, and if patient lived in the hospital's catchment area. The hospital characteristics include size and hospital classification according to the National Health System. Kaplan-Meier plots were used to examine differences in survival curves. Cox proportional hazard models with frailty were applied to identify independent predictors of hospital mortality and to calculate hazard ratios (HR).</p> <p>Results</p> <p>The Cox proportional model with frailty showed that male gender, older patient, great number of diagnoses and pneumonia increased the hazard of HIV related hospital mortality. On the other hand tuberculosis was associated with a reduced risk of death. Central hospital discharge also presents less risk of mortality.</p> <p>The frailty variance was small but statistically significant, indicating hazard ratio heterogeneity among hospitals that varied between 0.67 and 1.34, and resulted in two hospitals with HR different from the average risk.</p> <p>Conclusion</p> <p>The frailty model suggests that there are unmeasured factors affecting mortality in HIV associated hospitalizations. Consequently, for healthcare policy purposes, hospitals should not all be treated in an equal manner.</p

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV

The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of √s = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT≥20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60≤pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2≤{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration