Constant of Motion for several one-dimensional systems and outlining the problem associated with getting their Hamiltonians

The constants of motion of the following systems are deduced: a relativistic particle with linear dissipation, a no-relativistic particle with a time explicitly depending force, a no-relativistic particle with a constant force and time depending mass, and a relativistic particle under a conservative force with position depending mass. The problem of getting the Hamiltonian for these systems is determined by getting the velocity as an explicit function of position and generalized linear momentum, and this problem can be solved a first approximation for the first above system.Comment: 15 pages, Te

Estilo de vida y estado de nutrición en niños escolares

ResumenObjetivoRelacionar el estilo de vida y el estado de nutrición en escolares.MétodoEstudio correlacional, participaron 260 niños adscritos a la Clínica ISSSTE, elegidos aleatoriamente. Se utilizó el cuestionario sobre estilos de vida en la niñez y se valoró el peso y talla. Se obtuvo la aprobación de la Jefatura de Investigación del ISSSTE. En el análisis de datos se aplicó estadística descriptiva e inferencial.ResultadosParticiparon 137 niños y 123 niñas, con edades entre 6-12 años. Respecto al estado de nutrición, 5 de cada 10 de los participantes se encuentran en peso normal, 2 de cada 10 en sobrepeso y uno de cada 10 en obesidad y peso bajo. Sobre el estilo de vida 7 de cada 10 de los participantes se encontraron en riesgo bajo y 2 de cada 10 en riesgo mediano. Por otra parte, no se encontró relación entre el estilo de vida de los niños y su estado de nutrición (rs=0.038, p>0.05). Adicionalmente, se encontró que los niños con peso normal o bajo peso tienen mejores hábitos de sueño que los niños con sobrepeso u obesidad (U=3.79, p<0.001).ConclusionesEste estudio muestra indicios de que los aspectos vinculados con la dimensión psicocorporal y con uso del tiempo libre deberían indagarse a mayor profundidad, ya que fueron los que arrojaron cifras que ubican a los escolares en riesgo medio y alto.AbstractObjectiveTo explore the association between lifestyle and nutritional status among school children.MethodCorrelational study involving 260 children registered at an ISSSTE clinic, who were randomly selected. A questionnaire on childhood lifestyles was used; weight and height were also assessed. A project approval from the ISSSTE research committee was obtained. Descriptive and inferential statistics were used.Results137 boys and 123 girls with ages between 6 and 12 years old participated. In relation to the nutrition status, five out every ten have a normal weight; two out every ten are over weighted, and one out of every ten is obese or under weighted respectively. In relation to lifestyle, seven out of every ten participants have low risk; and two out of every ten have medium risk. On the other hand a relation between the lifestyle and nutritional status of the children was not found (rs=.038, p>0.05). Moreover, it was found that children with normal or low weights have better sleep habits in comparison to the children who are over weighted or obese U=3.79, p <.001).ConclusionsThis study suggests that issues related to the psychological and corporal dimensions, as well as the use of free time, should be further explored because they showed figures which place children within mid and high risks

Hyper, a Hydrogen Peroxide Sensor, Indicates the Sensitivity of the Arabidopsis Root Elongation Zone to Aluminum Treatment

Emerging evidence indicates that some reactive oxygen species (ROS), such as the superoxide anion radical and hydrogen peroxide (H2O2), are central regulators of plant responses to biotic and abiotic stresses. Thus, the cellular levels of ROS are thought to be tightly regulated by an efficient and elaborate pro- and antioxidant system that modulates the production and scavenging of ROS. Until recently, studies of ROS in plant cells have been limited to biochemical assays and the use of fluorescent probes; however, the irreversible oxidation of these fluorescent probes makes it impossible to visualize dynamic changes in ROS levels. In this work, we describe the use of Hyper, a recently developed live cell probe for H2O2 measurements in living cells, to monitor oxidative stress in Arabidopsis roots subjected to aluminum treatment. Hyper consists of a circularly permuted YFP (cpYFP) inserted into the regulatory domain of the Escherichia coli hydrogen peroxide-binding protein (OxyR), and is a H2O2-specific ratiometric, and therefore quantitative, probe that can be expressed in plant and animal cells. Now we demonstrate that H2O2 levels drop sharply in the elongation zone of roots treated with aluminum. This response could contribute to root growth arrest and provides evidence that H2O2 is involved in early Al sensing

Reporte de Pecari tajacu y Procyon lotor con anomalías cromáticas en el Estado de Guerrero, México

Este trabajo documenta el primer registro de anomalías cromáticas en el pecarí de collar (Pecari tajacu) y el tercero en el mapache (Procyon lotor) para México. Los hallazgos se realizaron durante el monitoreo realizado entre el 2009 y el 2021, utilizando cámaras-trampa, principalmente en la ecorregión de la Sierra Madre del Sur del estado de Guerrero, México. Procyon lotor fue registrado entre el 5 de noviembre y el 1 de diciembre de 2019, en vegetación riparia de bosque tropical caducifolio (17°47’35”N, 98°39’59”W, 1134 m de altitud). Mientras que Pecari tajacu se registró el 7 de junio y el 22 de julio del 2021 en una brecha saca cosecha abandonada (17°38’12”N, 100°40’50”W; 1532 m de altitud)

Memorias : Coloquio Vida Cotidiana y Diseño

1 archivo PDF (259 páginas)Memorias del coloquio realizado en noviembre de 2007 en las instalaciones de la UAM Azcapotzalco en donde la temática, incluyó investigaciones variadas que iban desde utensilios para comer hasta las librerías y vecindades en el siglo XIX, pasando por el diseño japonés, empaques y embalajes, cooperativas y la España Musulmana, todo esto relacionado con la vida cotidiana ya que dicho concepto está modificando la manera en que los científicos sociales se acercan a la realidad

Time course study of oxidative and nitrosative stress and antioxidant enzymes in K(2)Cr(2)O(7)-induced nephrotoxicity

BACKGROUND: Potassium dichromate (K(2)Cr(2)O(7))-induced nephrotoxicity is associated with oxidative and nitrosative stress. In this study we investigated the relation between the time course of the oxidative and nitrosative stress with kidney damage and alterations in the following antioxidant enzymes: Cu, Zn superoxide dismutase (Cu, Zn-SOD), Mn-SOD, glutathione peroxidase (GPx), glutathione reductase (GR), and catalase (CAT). METHODS: Nephrotoxicity was induced in rats by a single injection of K(2)Cr(2)O(7). Groups of animals were sacrificed on days 1,2,3,4,6,8,10, and 12. Nephrotoxicity was evaluated by histological studies and by measuring creatinine clearance, serum creatinine, blood urea nitrogen (BUN), and urinary excretion of N-acetyl-β-D-glucosaminidase (NAG) and total protein. Oxidative and nitrosative stress were measured by immunohistochemical localization of protein carbonyls and 3-nitrotyrosine, respectively. Cu, Zn-SOD, Mn-SOD, and CAT were studied by immunohistochemical localization. The activity of total SOD, CAT, GPx, and GR was also measured as well as serum and kidney content of chromium and urinary excretion of NO(2 )(-)/NO(3)(-). Data were compared by two-way analysis of variance followed by a post hoc test. RESULTS: Serum and kidney chromium content increased reaching the highest value on day 1. Nephrotoxicity was made evident by the decrease in creatinine clearance (days 1–4) and by the increase in serum creatinine (days 1–4), BUN (days 1–6), urinary excretion of NAG (days 1–4), and total protein (day 1–6) and by the structural damage to the proximal tubules (days 1–6). Oxidative and nitrosative stress were clearly evident on days 1–8. Urinary excretion of NO(2)(-)/NO(3)(- )decreased on days 2–6. Mn-SOD and Cu, Zn-SOD, estimated by immunohistochemistry, and total SOD activity remained unchanged. Activity of GPx decreased on days 3–12 and those of GR and CAT on days 2–10. Similar findings were observed by immunohistochemistry of CAT. CONCLUSION: These data show the association between oxidative and nitrosative stress with functional and structural renal damage induced by K(2)Cr(2)O(7). Renal antioxidant enzymes were regulated differentially and were not closely associated with oxidative or nitrosative stress or with kidney damage. In addition, the decrease in the urinary excretion of NO(2)(-)/NO(3)(- )was associated with the renal nitrosative stress suggesting that nitric oxide was derived to the formation of reactive nitrogen species involved in protein nitration

The role of interfacial lipids in stabilizing membrane protein oligomers

Oligomerization of membrane proteins in response to lipid binding has a critical role in many cell-signalling pathways1 but is often difficult to define2 or predict3. Here we report the development of a mass spectrometry platform to determine simultaneously the presence of interfacial lipids and oligomeric stability and to uncover how lipids act as key regulators of membrane-protein association. Evaluation of oligomeric strength for a dataset of 125 α-helical oligomeric membrane proteins reveals an absence of interfacial lipids in the mass spectra of 12 membrane proteins with high oligomeric stability. For the bacterial homologue of the eukaryotic biogenic transporters (LeuT4, one of the proteins with the lowest oligomeric stability), we found a precise cohort of lipids within the dimer interface. Delipidation, mutation of lipid-binding sites or expression in cardiolipin-deficient Escherichia coli abrogated dimer formation. Molecular dynamics simulation revealed that cardiolipin acts as a bidentate ligand, bridging across subunits. Subsequently, we show that for the Vibrio splendidus sugar transporter SemiSWEET5, another protein with low oligomeric stability, cardiolipin shifts the equilibrium from monomer to functional dimer. We hypothesized that lipids are essential for dimerization of the Na+/H+ antiporter NhaA from E. coli, which has the lowest oligomeric strength, but not for the substantially more stable homologous Thermus thermophilus protein NapA. We found that lipid binding is obligatory for dimerization of NhaA, whereas NapA has adapted to form an interface that is stable without lipids. Overall, by correlating interfacial strength with the presence of interfacial lipids, we provide a rationale for understanding the role of lipids in both transient and stable interactions within a range of α-helical membrane proteins, including G-protein-coupled receptors

Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30

Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations