Langevin equation for the collective motions of a binary astrophysical system.

According to Thirring's condition, the thermodynamic equilibrium is not possible between two systems with negative heat capacities. Since the existence of negative heat capacity is a rule rather an exception in astrophysics, we would like to analyze the possibility of the thermodynamic equilibrium for a paradigmatic astrophysical situation: the binary system. The possible explanation arises after decomposing the dynamical variables into internal and collective degrees of freedom, which enables us to reinterpret binary systems as two systems A and B that interact between them through a third low dimensional system C. Our central result is the derivation of a Langevin equation to describe the dynamics of the collective degrees of freedom. Our preliminary analysis evidences that the proposed framework is able not only to describe the system stability, but also unstable processes, such as escape or collapse of the binary system. These processes crucially depend on the angular momentum, the quadrupole-orbit coupling among internal and collective degrees of freedom, as well as internal temperatures of each system.

Quantitative methods to determine the student workload: II. Statistical models for the microcurricular performance indicators.

Previously, we observed that the student workload follows an inverse relation with the learning rate (an application of the kinematic notion of speed contextualized to the learning process). Motivated by this finding, we propose a quantitative estimation of the learning rate using a different source of information: the historical records of final grades of a given course. According to empirical data analyzed in other similar studies, the distribution functions of final grades exhibit a regular pattern: a Gaussian behavior for the approval region and a homogeneous distribution for the failed one. This fact is combined with the incidence of student elimination-desertion rules for introducing two simple agent-based models. Our analysis is complemented by revisiting the performance indicators typically employed to characterize the student promotion and progression. We discuss some other performance indicators to characterize the learning advancement of students: the group learning rate and the learning curve. We compare the results of Monte Carlo simulations with empirical data, observing a good agreement in the behavior of performance indicators derived from these sources. This analysis suggests an adaptive method for the readjustment of the student workload (the number of academic credits) considering the group learning rates during a follow-up period, which resembles the readjustment of prices of goods (and services) in correspondence with the evolution of supply and demand.

Quantitative methods to determine the student workload. I. Empirical study based on digital platforms.

We present a quantitative study of an online course developed during COVID19 sanitary emergency in Chile. We reconstruct the teaching-learning process considering the activity logs on digital platforms in order to answer the question of How do our students study? The results from the analysis evidence the complex adaptive character of the academic environment, which exhibits regularities similar to those found in financial markets (e.g., distributions of the daily time devoted to learning activities follow patterns like Pareto's or Zipf's law). Our empirical results illustrate (i) the relevance of economic notions in the understanding of the teaching-learning processes and (ii) the reliability of quantitative methods based on digital platforms to conduct experimental studies in this framework. We introduce in the present work a series of indicators to characterize the performance of professors, students' follow-up of the course, and their learning progress by crossing information with the results of assessments. In this context, the learning rate appears as a key statistical descriptor for the allocation of the student workload.

Quantum Walks: Schur Functions Meet Symmetry Protected Topological Phases.

This paper uncovers and exploits a link between a central object in harmonic analysis, the so-called Schur functions, and the very hot topic of symmetry protected topological phases of quantum matter. This connection is found in the setting of quantum walks, i.e. quantum analogs of classical random walks. We prove that topological indices classifying symmetry protected topological phases of quantum walks are encoded by matrix Schur functions built out of the walk. This main result of the paper reduces the calculation of these topological indices to a linear algebra problem: calculating symmetry indices of finite-dimensional unitaries obtained by evaluating such matrix Schur functions at the symmetry protected points ± 1 . The Schur representation fully covers the complete set of symmetry indices for 1D quantum walks with a group of symmetries realizing any of the symmetry types of the tenfold way. The main advantage of the Schur approach is its validity in the absence of translation invariance, which allows us to go beyond standard Fourier methods, leading to the complete classification of non-translation invariant phases for typical examples.

Influence of clinical and psychological variables upon the oral health-related quality of life in patients with temporomandibular disorders.

BACKGROUND: To analyze the association between the OHIP-14 and the different subtypes making up the clinical and psychological axis obtained using the RDC/TMD. MATERIAL AND METHODS: 407 patients treated at the TMD unit of the Andalusian Healthcare Service were administered the Spanish version of the Research Diagnostic Criteria for Temporomandibular Disorders questionnaire (RDC/TMD), together with the Oral Health Impact Profile questionnaire (OHIP-14). The degree of association between the patients' score in the OHIP-14 and the clinical and biopsychosocial variables was analyzed through bivariate and multivariate analyses, specifically through linear regression. RESULTS: 89.4% of the treated patients were women, while 10.6% were men, with an average age of 42.08 ± 14.9 years. The mean score and standard deviation for the OHIP-14 was 20.57 ± 10.73. A significant association (p < 0.05) was observed with the following variables: Axis I, jaw disability checklist, depression, somatization, perceived pain duration, and pain interference with activities of daily living. CONCLUSIONS: The analysis of the relation between self-perceived health in patients with TMD, as measured by the OHIP-14, showed a R2 of 0.3979, with a higher Beta value for the association between the OHIP and patients with both myofascial pain and arthopathy, jaw disability, depression, a higher pain duration and a higher pain interference with activities of daily living.

HPV 16 and 18 viral loads are greater in patients with high-grade cervical epithelial lesions.

BACKGROUND: Cervical cancer is the second most common cancer in women worldwide. High-risk infection with HPV type 16 or type 18 is the most important risk factor associated with the development of cervical cancer. AIMS: To determine the viral load of HPV-16 and HPV-1 8 in samples from women with cervical epithelial lesion in the State of Colima, Mexico. MATERIALS AND METHODS: A cross-sectional analytic study was conducted that included 45 samples positive for HPV- 16 and 45 samples positive for HPV-1 8 from patients with cervical cancer or precursor lesion. Real time PCR was employed to determine the number of copies /101 cells. Viral load was determined in the two groups of patients and correlated with tumor grade. RESULTS: THe authors found that the HPV-1 6 viral load was greater than that of HPV-18 through a Mann-Whitney U analysis, resulting in ap = 0.000; as the malignancy of the cervical lesion progressed, the viral load increased, and HPV-16 showed a moderate positive association with an r = 0.509 and a p = 0.000, whereas HPV-18 showed a weak positive correlation with an r = 0.372 and a p = 0.0 12. CONCLUSIONS: The viral load of HPV-16 was greater than that of HPV-18. The HPV-16 viral load had a moderate positive association in relation to cervical lesion severity, whereas the viral load of HPV- 18 had a weak positive correlation with respect to the cervical lesion grade.

[The modified Brussels scale as a predictor of mortality in the Intensive Care Unit]. / La escala modificada de Bruselas como predictor de mortalidad en la Unidad de Terapia Intensiva.

PURPOSE: To compare discrimination and calibration of the modified Brussels score with the Simplified Acute Physiology Score version 3 (SAPS-3) in predicting mortality. DESIGN: A prospective cohort study was carried out. SETTING: The Respiratory Intensive Care Unit (RICU) of Mexico General Hospital. PATIENTS: A total of 251 patients out of 285 admissions to the RICU in 2012 were included. The mean age was 48.4±17.1 years, and 132 of the patients were men (52.8%). INTERVENTIONS: None. VARIABLES OF INTEREST: Demographic data, SAPS-3 score upon admission and the modified Brussels score on the day 1 of stay in the RICU. RESULTS: On day 1, the modified Brussels and SAPS-3 scores were 4.7 ± 3.8 and 54.7 ± 17.8, respectively. Areas under the ROC curve for the modified Brussels score on day 1 and the SAPS-3 were 0.837 ± 0.025 (95% CI 0.787-0.887) and 0.813 ± 0.027 (95% CI 0.761-0.865), respectively. Hosmer-Lemeshow goodness-of-fit values were 5,885 (P=.660) and 4,026 (P=.855), respectively. CONCLUSIONS: The modified Brussels score on day 1 offers excellent discrimination and calibration in predicting mortality in the RICU, comparable to that of the SAPS-3.

Application of an oral health-related quality of life questionnaire in primary care patients with orofacial pain and temporomandibular disorders.

OBJECTIVES: To examine whether patients who report orofacial pain (OP) and temporomandibular disorders (TMD) have a poorer perception of their oral health-related quality of life and, if so, to what extent, and to analyze the association between oral health perception, sociodemographic variables and reported pain duration. STUDY DESIGN: 407 patients treated at the OP and TMD units in the Healthcare District of Cordoba, Spain, diagnosed following the standard criteria accepted by the scientific community - the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) - were administered the Spanish version of the Oral Health Impact Profile questionnaire (OHIP-14). Bivariate and logistic regression analyses were performed to determine the degree of association between the patients' OHIP-14 score and pain duration, pain intensity, and various sociodemographic variables. RESULTS: The observed distribution was 89.4% women and 10.6% men. The mean OHIP-14 score was 20.57 ± 10.73 (mean ± standard deviation). A significant association (p<0.05) was found for gender, age, marital status, chronic pain grade, self-perceived oral health status and pain duration. CONCLUSIONS: The analysis of self-perceived oral health status in patients with OP and TMD, as measured by the OHIP-14, showed that oral health is perceived more negatively by women. Moreover, a one-point increase in the Chronic Pain Grade indicator increases the OHIP-14 indicator by 4.6 points, while chronic pain, defined as pain suffered by patients for one year or more, increases the OHIP-14 indicator by 3.2 points.

[Association of family support and knowledge about the disease with glycemic control in diabetic patients]. / Asociación del control glicémico con el apoyo familiar y el nivel de conocimientos en pacientes con diabetes tipo 2.

BACKGROUND: Family interventions may improve glycemic control among diabetic patients AIM: To evaluate the association of glycemic control with family support and level of knowledge in patients with type 2 diabetes. MATERIAL AND METHODS: Patients with type 2 diabetes completed a demographic survey. Glycosylated hemoglobin (HbA1c) was determined and glycemic control was defined as a value < 6,5%. Two validated instruments were applied to evaluate family support, stratifying it in three categories (low, medium and high) and the level of knowledge about diabetes. RESULTS: We studied 81 patients aged 32 to 65 years (53 females). Thirty six percent had an adequate glycemic control. Participants with a medium family support had three times greater risk of having an uncontrolled blood glucose than subjects with high family support. No significant association was found between the level of knowledge and glycemic control. CONCLUSIONS: Family support but not knowledge about the disease is associated with a better glycemic control of patients with type 2 diabetes.

[Thoracoscopic treatment of secondary pneumothorax to costal osteochondroma]. / Tratamiento toracoscópico del neumotórax secundario a osteocondroma costal.

Costal osteochondromas are benign, uncommon and usually asymptomatic tumors, but may be associated with severe intrathoracic complications such as pneumothorax, hemothorax, nerve or vascular injury and fractures. We report a 12 year old patient, who presented a right spontaneous pneumothorax, which did not improve with standard treatment. Thoracic CT showed a costal exostosis of 2.5 cm in length. Excision was performed by videothoracoscopy (VATS), with good postoperative course. We consider the thoracoscopic approach as the most appropriate initial way in this type of tumors.

Psychological repercussions on nursing staff due to the COVID-19 pandemic: A cross-sectional study.

INTRODUCTION: The coronavirus disease 2019 (COVID-19) pandemic has caused a high demand for health services, especially nursing. This workload can lead to emotional distress affecting their daily lives on a personal and professional basis. OBJECTIVE: To examine the prevalence of depression, anxiety, and stress in nurses and to analyze the factors associated with their presence during the COVID-19 pandemic. METHODS: An observational cross-sectional descriptive study was carried out in a second-level hospital in Mexico between September and October 2020. Within a population of 150 nurses invited to the study, 116 participated by answering a questionnaire regarding emotional aspects during their time caring for COVID-19 patients, as well as using the depression, anxiety, and stress scale (DASS-21). RESULTS: Among de 116 participants, 77.6% were females, and 22.4% were males. The 91.4% reported fear of spreading the disease to their families, and 59.5% reported that the death of their patients infected with COVID-19 affected them deeply. The factors associated with moderate to extremely severe levels of depression were the attitude of indifference from the community to their work during the pandemic (OR:2.66) and the increase consumption of addictive substances (OR:9.80). In the stress subscale, the variables that conferred a significant association was working inside the COVID-19 area (OR:17.05), being severely affected by the death of patients infected (OR:4.23), and fear of entering the red zone (OR:19.47). The need for psychological care was associated with moderate to severe depression and anxiety (OR:7.38, OR:9.50, respectively). For the anxiety subscale, no association with the studied variables was found. CONCLUSIONS: The study indicates a high prevalence of emotional distress among nurses, and that there were working, psychological and social factors associated with symptoms of depression and stress. Future research should focus on prevention measures and strategies to reduce psychological impact, as this could affect the quality of care provided to their patients.

Biochemical characterization and insecticidal activity of isolated peptides from the venom of the scorpion Centruroides tecomanus.

The venom of scorpions is a mixture of components that constitute a source of bioactive molecules. The venom of the scorpion Centruroides tecomanus contains peptides toxic to insects, however, to date no toxin responsible for this activity has yet been isolated and fully characterized. This communication describes two new peptides Ct-IT1 and Ct-IT2 purified from this scorpion. Both peptides contain 63 amino acids with molecular weight 6857.85 for Ct-IT1 and 6987.77 Da for Ct-IT2. The soluble venom was separated using chromatographic techniques of molecular size exclusion, cationic exchange, and reverse phase chromatography, allowing the identification of at least 99 components of which in 53 the insecticidal activity was evaluated. The LD50 determined for Ct-IT1 is 3.81 µg/100 mg of cricket weight, but low amounts of peptides (0.8 µg of peptide) already cause paralysis in crickets. The relative abundance of these two peptides in the venom is 2.1% for Ct-IT1 and 1% for Ct-IT2. The molecular masses and N-terminal sequences of both insecticidal toxins were determined by mass spectrometry and Edman degradation. The primary structure of both toxins was compared with other known peptides isolated from other scorpion venoms. The analysis of the sequence alignments revealed the position of a highly conserved amino acid residue, Gly39, exclusively present in anti-insect selective depressant ß-toxins (DBTXs), which in Ct-IT1 and Ct-IT2 is at position Gly40. Similarly, a three-dimensional structure of this toxins was obtained by homology modeling and compared to the structure of known insect toxins of scorpions. An important similarity of the cavity formed by the trapping apparatus region of the depressant toxin LqhIT2, isolated from the scorpion Leiurus quinquestriatus hebraeus, was found in the toxins described here. These results indicate that Ct-IT1 and Ct-IT2 toxins have a high potential to be evaluated on pests that affect economically important crops to eventually consider them as a potential biological control method.

Alternative model of the Antonov problem: generalization with the presence of a mass spectrum.

We extend the quasiergodic model proposed as an alternative version of the Antonov isothermal model [L. Velazquez and F. Guzman, Phys. Rev. E 68, 066116 (2003)] by including the incidence of a mass spectrum. We propose an iterative procedure inspired by the Newton-Raphson method to solve the resulting nonlinear structure equations. As an example of application, we assume the existence of a mass spectrum with a standard Salpeter form, dN=Cdmm;{alpha} . We analyze consequences of this realistic ingredient on the system thermodynamical behavior and perform a quantitative description of the mass segregation effect.

Faunal mortality associated with massive beaching and decomposition of pelagic Sargassum.

In 2018, the Mexican Caribbean coast received a massive influx of pelagic Sargassum spp. that accumulated and decayed on beaches producing organic decomposition products that made the water turbid and brown. Between May and September of the same year there were several reports of mass mortality of marine biota in this area. From these reports we estimate that organisms belonging to 78 faunal species died as result of this event, with demersal neritic fish and Crustacea being the most affected groups. The cause of mortality appears to be the combined effect of high ammonium and hydrogen sulfide concentrations, together with hypoxic conditions. If massive arrival of pelagic Sargassum spp. continues and algae is left to decay on the beach in large volumes then deterioration in water quality could affect coral reefs close to shore. Furthermore, barriers placed in lagoons to intercept the Sargassum spp. before it reaches the beach could impact reef fauna if the algae is left to die and sink on site.

Study of the Automatic Detection of Parkison's Disease Based on Speaker Recognition Technologies and Allophonic Distillation.

The use of new tools to detect Parkinson's Disease (PD) from speech articulatory movements can have a considerable impact in the diagnosis of patients. In this study, a novel approach involving speaker recognition techniques with allophonic distillation is proposed and tested separately in four parkinsonian speech databases (205 patients and 186 controls in total). This new scheme provides values between 72% and 94% of accuracy in the automatic detection of PD, depending on the database, and improvements up to 9% respect to baseline techniques. Results not only point towards the importance of the segmentation of the speech for the differentiation of parkinsonian and control speakers but confirm previous findings about the relevance of plosives and fricatives in the detection of parkinsonian dysarthria.

Asymptomatic Intestinal Colonization with Protist Blastocystis Is Strongly Associated with Distinct Microbiome Ecological Patterns.

Blastocystis is the most prevalent protist of the human intestine, colonizing approximately 20% of the North American population and up to 100% in some nonindustrialized settings. Blastocystis is associated with gastrointestinal and systemic disease but can also be an asymptomatic colonizer in large populations. While recent findings in humans have shown bacterial microbiota changes associated with this protist, it is unknown whether these occur due to the presence of Blastocystis or as a result of inflammation. To explore this, we evaluated the fecal bacterial and eukaryotic microbiota in 156 asymptomatic adult subjects from a rural population in Xoxocotla, Mexico. Colonization with Blastocystis was strongly associated with an increase in bacterial alpha diversity and broad changes in beta diversity and with more discrete changes to the microbial eukaryome. More than 230 operational taxonomic units (OTUs), including those of dominant species Prevotella copri and Ruminococcus bromii, were differentially abundant in Blastocystis-colonized individuals. Large functional changes accompanied these observations, with differential abundances of 202 (out of 266) predicted metabolic pathways (PICRUSt), as well as lower fecal concentrations of acetate, butyrate, and propionate in colonized individuals. Fecal calprotectin was markedly decreased in association with Blastocystis colonization, suggesting that this ecological shift induces subclinical immune consequences to the asymptomatic host. This work is the first to show a direct association between the presence of Blastocystis and shifts in the gut bacterial and eukaryotic microbiome in the absence of gastrointestinal disease or inflammation. These results prompt further investigation of the role Blastocystis and other eukaryotes play within the human microbiome. IMPORTANCE Given the results of our study and other reports of the effects of the most common human gut protist on the diversity and composition of the bacterial microbiome, Blastocystis and, possibly, other gut protists should be studied as ecosystem engineers that drive community diversity and composition.

Kindling increases aversion to saccharin in taste aversion learning.

Kindling is a model in which an initially subconvulsive electrical stimulation of certain brain areas eventually develops a generalized seizure that produces behavioral and long term neuronal changes. In the present study we evaluated if kindling can modify conditioning taste aversion (CTA). In this paradigm animals acquire aversion to saccharin when it is presented as the conditioned stimulus (CS) followed by an injection of lithium chloride (LiCl) that induces a gastric irritation as the unconditioned stimulus (US). Male Wistar rats were implanted with bipolar electrodes aimed at the right amygdala (AMG) or at the right insular cortex (IC). The animals were stimulated daily until they reached stages 2-4 (intermediate) or until kindling was fully established (three consecutive stage 5 seizures). At least two weeks after kindling stimulation had ceased the animals were deprived of water for 24 h and given 10-min drinking sessions twice a day for 4 days. On day 5 (morning session) tap water was replaced by saccharin solution (0.1%), 20 min later the animals were injected with LiCl (7.5 ml/kg i.p., 0.2 M) to induce gastric malaise or taste aversion. After three more days of baseline consumption, water was substituted by a fresh 0.1% saccharin solution to test the aversion. AMG-kindling delayed the extinction of CTA. Animals with kindling in the IC had a higher retention than the sham kindling group; that is, they drank significantly less saccharin solution than the other groups. The results of the present experiment show that local modification of brain function induced by kindling stimulation can prolong the aversive effects of CTA.

Isolation and characterization of Shiga toxin-producing Escherichia coli O157:H7 and non-O157 from beef carcasses at a slaughter plant in Mexico.

The contamination of beef carcasses with Shiga toxin-producing O157:H7 and non-O157 Escherichia coli (STEC) obtained from a slaughter plant in Guadalajara, Mexico was investigated. A total of 258 beef carcasses were sampled during a 12-month period. All samples were assayed for STEC by selective enrichment in modified tryptone soy broth supplemented with cefixime, cefsulodin and vancomycin, followed by plating on Sorbitol MacConkey Agar supplemented with cefixime and tellurite (CT-SMAC). Simultaneously, all samples were assayed by immunomagnetic separation (IMS) and plated on CT-SMAC and CHROMagar. The presence of the stx1, stx2, eaeA and hly933 genes, recognized as major virulence factors of STEC, was tested for O157:H7 and non-O157 E. coli isolates by multiplex polymerase chain reaction (PCR). STEC was detected in two (0.8%) samples. One of these STEC isolates corresponded to the serotype O157:H7 showing stx2, eaeA and hyl933 genes. The other isolate corresponded to non-O157 STEC and only had the stx1 gene. Thirteen carcasses (5%) were positive for nonmotile E. coli O157 and 7 (2.7%) were positive for E. coli O157:H7. The presence of O157:H7 and non-O157 STEC on beef carcasses in this slaughter plant in Guadalajara, Mexico, emphasizes the importance of implementing the Hazard Analysis and Critical Control Point (HACCP) system, as well as the need for implementing, evaluating, and validating antimicrobial interventions to reduce the presence of potential pathogenic microorganisms.

Choroid plexus carcinoma: a rare condition and its therapeutic management.

Choroid plexus carcinomas are rare tumours, found chiefly during childhood. The commonest pattern of progression is via the neural axis. We present the case of a patient with unusual metastatic dissemination, affecting lungs and bones two years after diagnosis, and the approach adopted towards him.