Solitary waves in the Nonlinear Dirac Equation

In the present work, we consider the existence, stability, and dynamics of solitary waves in the nonlinear Dirac equation. We start by introducing the Soler model of self-interacting spinors, and discuss its localized waveforms in one, two, and three spatial dimensions and the equations they satisfy. We present the associated explicit solutions in one dimension and numerically obtain their analogues in higher dimensions. The stability is subsequently discussed from a theoretical perspective and then complemented with numerical computations. Finally, the dynamics of the solutions is explored and compared to its non-relativistic analogue, which is the nonlinear Schr{\"o}dinger equation. A few special topics are also explored, including the discrete variant of the nonlinear Dirac equation and its solitary wave properties, as well as the PT-symmetric variant of the model

Bienestar psicológico como factor protector ante el consumo de alcohol en estudiantes universitarios

Introduction: the psychological wellness is the personal experience that is built through the individual´s mental development and the ability to relate in a positive and integrated way with life experiences, considering the positive and negative aspects, if to the above, alcohol can cause a decompensation among those involved causing health problems such as mental and behavioral disorders. Objective: determine if the psychological wellness influences as a protective as a factor against alcohol consumption in university students. Method: quantitative, descriptive, correlational, prospective and cross sectional, applying the wellness psychological Scale by Ryff and the Test AUDIT applied to 307 students of the Nursing Degree from the Universidad Veracruzana. Results: according to the Kolmogorov and Smirnov test the variables did not show normality the Spearman test was applied, this relationship between psychological well-being and alcohol consumption showed (rs= 1.020, p >0.05), according to age (rs= .221, p <0.01) according to the people with who they live (rs= .159, p <0.01) and witch semester they are studying (rs= .182, p <0.01). Discussion: the results coincide with different investigations where the same variables were studied and identified approving the null hypothesis; the psychological well-being influences in a neutral way in the consumption of alcohol in college students as a protector factor. Conclusion: 52.8% with high psychological well-being, 20.5% do not consume alcohol, while 32.3%, yes, classifying as sensible (18.9%), 7.8% dependent or risk and 5.3% harmful, the above, rejects the belief that psychological well-being influences alcoholic behavior.Introducción: el bienestar psicológico es la experiencia personal que se va construyendo a través del desarrollo mental del individuo y capacidad para relacionarse de manera positiva e integrada con las experiencias de vida, considerando los aspectos positivos y negativos, si a lo anterior, se agrega el consumo de alcohol puede existir una descompensación entre ambos, causando problemas de salud como trastornos mentales y comportamentales. Objetivo: determinar si el bienestar psicológico influye como factor protector ante el consumo de alcohol en estudiantes universitarios. Método: cuantitativo, descriptivo, correlacional, prospectivo y corte trasversal, aplicando la Escala de Bienestar Psicológico de Ryff y el Test AUDIT, a 307 estudiantes de la Licenciatura de Enfermería de la Universidad Veracruzana. Resultados: según la prueba de Kolmogorov y Smirnov, las variables no mostraron normalidad, se aplicó la prueba de Spearman, dicha relación entre bienestar psicológico y consumo de alcohol mostró (rs= 1.020, p >0.05), pero por la Edad (rs= .221, p <0.01), Con quien viven (rs= .159, p <0.01) y Semestre que cursa actualmente (rs= .182, p <0.01). Discusión: Los resultados coinciden con diferentes investigaciones, donde se estudiaron e identificaron las mismas variables, aprobándose la hipótesis nula: el bienestar psicológico influye de manera neutra en el consumo de alcohol en estudiantes universitarios como factor protector. Conclusión: el 52.8% con un bienestar psicológico alto, el 20.5% no consume alcohol, mientras que el 32.3%, sí, clasificándose en sensato (18.9%), 7.8% dependiente o riesgo y el 5.3% perjudicial, lo anterior, rechaza la creencia que el bienestar psicológico influye en la conducta alcohólica

Deep-Inelastic Inclusive ep Scattering at Low x and a Determination of alpha_s

A precise measurement of the inclusive deep-inelastic e^+p scattering cross section is reported in the kinematic range 1.5<= Q^2 <=150 GeV^2 and 3*10^(-5)<= x <=0.2. The data were recorded with the H1 detector at HERA in 1996 and 1997, and correspond to an integrated luminosity of 20 pb^(-1). The double differential cross section, from which the proton structure function F_2(x,Q^2) and the longitudinal structure function F_L(x,Q^2) are extracted, is measured with typically 1% statistical and 3% systematic uncertainties. The measured partial derivative (dF_2(x,Q^2)/dln Q^2)_x is observed to rise continuously towards small x for fixed Q^2. The cross section data are combined with published H1 measurements at high Q^2 for a next-to-leading order DGLAP QCD analysis.The H1 data determine the gluon momentum distribution in the range 3*10^(-4)<= x <=0.1 to within an experimental accuracy of about 3% for Q^2 =20 GeV^2. A fit of the H1 measurements and the mu p data of the BCDMS collaboration allows the strong coupling constant alpha_s and the gluon distribution to be simultaneously determined. A value of alpha _s(M_Z^2)=0.1150+-0.0017 (exp) +0.0009-0.0005 (model) is obtained in NLO, with an additional theoretical uncertainty of about +-0.005, mainly due to the uncertainty of the renormalisation scale.Comment: 68 pages, 24 figures and 18 table

Academic stress in nursing undergraduates, a longitudinal cross-sectional study in covid-19 times

Introducción: el confinamiento vivido por el SARS-Cov2 ha modificado la forman en que el mundo funcionaba, sin embargo, el mayor impacto ha sido recibido en tres sectores, el sanitario, económico y educativo, siendo este último el punto de partida para la realización de la presente investigación. Objetivo: comparar la media de estrés académico en un grupo de alumnos de la licenciatura en enfermería en dos períodos durante la pandemia por Covid-19. Materiales y métodos: estudio cuantitativo, descriptivo, comparativo y longitudinal, aplicando el Inventario SISCO-24, con un muestreo no probabilístico consecutivo. Resultados y discusión: 75.0% de la población pertenece al sexo femenino, 38.8% estudia y trabajan simultáneamente, la edad promedio es de 19.72± DE 1.43, los dominios que resultaron más afectados son los síntomas físicos y psicológicos (ME: 14.63± DE 4.38; ME: 15.99± DE 4.44) y a través de la prueba t de Student para muestras relacionadas se identificó que no existen diferencias significativas entre las medias de estrés académico (t= 0.13; Sig. Bilateral: .990). Conclusión: los métodos de educación virtuales manifiestan una incompatibilidad con el proceso enseñanza-aprendizaje, señalando que el aumento de factores estresores académicos es persistente y mantiene niveles peligrosamente elevados que amenazan a la salud mentalIntroduction: the confinement experienced by SARS-Cov2 has modified the way in which the world functioned; however, the greatest impact has been received in three sectors, health, economic and educational, the latter being the starting point for this research. Objective: to compare the mean academic stress in a group of nursing students in two periods during the Covid-19 pandemic. Materials and methods: quantitative, descriptive, comparative, and longitudinal study, applying the SISCO-24 Inventory, with non-probabilistic consecutive sampling. Results and discussion: 75.0% of the population was female, 38.8% studied and worked simultaneously, the mean age was 19.72 SD 1.43, the most affected domains were physical and psychological symptoms (ME: 14.63 SD 4.38; ME: 15.99 SD 4.44) and through the student’s t-test for related samples it was identified that there were no significant differences between the means of academic stress (t= 0.13; Bilateral Sig.: .990). Conclusion: virtual education methods manifest an incompatibility with the teaching-learning process, indicating that the increase of academic stressors is persistent and maintains dangerously high levels that threaten mental healt

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

The azimuthal anisotropy of charged particles in PbPb collisions at nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS detector at the LHC over an extended transverse momentum (pt) range up to approximately 60 GeV. The data cover both the low-pt region associated with hydrodynamic flow phenomena and the high-pt region where the anisotropies may reflect the path-length dependence of parton energy loss in the created medium. The anisotropy parameter (v2) of the particles is extracted by correlating charged tracks with respect to the event-plane reconstructed by using the energy deposited in forward-angle calorimeters. For the six bins of collision centrality studied, spanning the range of 0-60% most-central events, the observed v2 values are found to first increase with pt, reaching a maximum around pt = 3 GeV, and then to gradually decrease to almost zero, with the decline persisting up to at least pt = 40 GeV over the full centrality range measured.Comment: Replaced with published version. Added journal reference and DO

Search for new physics with same-sign isolated dilepton events with jets and missing transverse energy

A search for new physics is performed in events with two same-sign isolated leptons, hadronic jets, and missing transverse energy in the final state. The analysis is based on a data sample corresponding to an integrated luminosity of 4.98 inverse femtobarns produced in pp collisions at a center-of-mass energy of 7 TeV collected by the CMS experiment at the LHC. This constitutes a factor of 140 increase in integrated luminosity over previously published results. The observed yields agree with the standard model predictions and thus no evidence for new physics is found. The observations are used to set upper limits on possible new physics contributions and to constrain supersymmetric models. To facilitate the interpretation of the data in a broader range of new physics scenarios, information on the event selection, detector response, and efficiencies is provided.Comment: Published in Physical Review Letter

Optic Nerve Head Change in Non-Arteritic Anterior Ischemic Optic Neuropathy and Its Influence on Visual Outcome

To evaluate changes in cup/disc (C/D) diameter ratios and parapapillary atrophy in patients with non-arteritic anterior ischemic optic neuropathy (NA-AION), using morphometric methods.The clinical non-interventional study included 157 patients with unilateral or bilateral NA-AION. Optic disc photographs taken from both eyes at the end of follow-up were morphometrically examined.Follow-up was 86.3±70.3 months. Horizontal and vertical disc diameters (P = 0.30;P = 0.61, respectively), horizontal and vertical C/D ratios (P = 0.47;P = 0.19,resp.), and size of alpha zone and beta zone of parapapillary atrophy (P = 0.27;P = 0.32,resp.) did not differ significantly between affected eyes and contralateral normal eyes in patients with unilateral NA-AION. Similarly, horizontal and vertical disc diameters, horizontal and vertical C/D ratios, and size of alpha zone and beta zone did not vary significantly (all P>0.05) between the unaffected eyes of patients with unilateral NA-AION and the eyes of patients with bilateral NA-AION. Optic disc diameters, C/D ratios, size of alpha zone or beta zone of parapapillary atrophy were not significantly associated with final visual outcome in the eyes affected with NA-AION (all P>0.20) nor with the difference in final visual acuity between affected eyes and unaffected eyes in patients with unilateral NA-AION (all P>0.25).NA-AION did not affect C/D ratios nor alpha zone and beta zone of parapapillary atrophy. Optic disc size was not related to the final visual acuity outcome in NA-AION

Measurement of jet fragmentation into charged particles in pp and PbPb collisions at sqrt(s[NN]) = 2.76 TeV

Jet fragmentation in pp and PbPb collisions at a centre-of-mass energy of 2.76 TeV per nucleon pair was studied using data collected with the CMS detector at the LHC. Fragmentation functions are constructed using charged-particle tracks with transverse momenta pt > 4 GeV for dijet events with a leading jet of pt > 100 GeV. The fragmentation functions in PbPb events are compared to those in pp data as a function of collision centrality, as well as dijet-pt imbalance. Special emphasis is placed on the most central PbPb events including dijets with unbalanced momentum, indicative of energy loss of the hard scattered parent partons. The fragmentation patterns for both the leading and subleading jets in PbPb collisions agree with those seen in pp data at 2.76 TeV. The results provide evidence that, despite the large parton energy loss observed in PbPb collisions, the partition of the remaining momentum within the jet cone into high-pt particles is not strongly modified in comparison to that observed for jets in vacuum.Comment: Submitted to the Journal of High Energy Physic