1,892 research outputs found
Limits of Predictability in Commuting Flows in the Absence of Data for Calibration
The estimation of commuting flows at different spatial scales is a fundamental problem for different areas of study. Many current methods rely on parameters requiring calibration from empirical trip volumes. Their values are often not generalizable to cases without calibration data. To solve this problem we develop a statistical expression to calculate commuting trips with a quantitative functional form to estimate the model parameter when empirical trip data is not available. We calculate commuting trip volumes at scales from within a city to an entire country, introducing a scaling parameter α to the recently proposed parameter free radiation model. The model requires only widely available population and facility density distributions. The parameter can be interpreted as the influence of the region scale and the degree of heterogeneity in the facility distribution. We explore in detail the scaling limitations of this problem, namely under which conditions the proposed model can be applied without trip data for calibration. On the other hand, when empirical trip data is available, we show that the proposed model's estimation accuracy is as good as other existing models. We validated the model in different regions in the U.S., then successfully applied it in three different countries
Joves adolescents i escolaritat obligatòria : sis contraarguments i una coda
En els temps que corren topem massa sovint amb interpretacions múltiples del fracàs escolar. L'extensió de l'escolarització obligatòria fins als setze anys, l'arribada constant d'immigrants a les escoles i els instituts de Catalunya, la creixent violència juvenil a les aules, la desaparició dels valors tradicionals de la "família", són, a tall d'exemple, alguns dels factors que són assenyalats des de fonts diverses (i sovint de validesa qüestionable) com a causes principals de la disrupció i el fracàs dels joves adolescents. Aquestes interpretacions, facilitades en bona mesura per algunes tendències mediàtiques obsessionades amb la demonització de la joventut, proporcionen lectures simples i simplistes de les posicions escolars dels joves. Redueixen els matisos i la complexitat de les relacions socials a interpretacions de "blanc o negre" alhora que cerquen causes úniques per explicar els problemes socials. Són interpretacions, però, que acompleixen una clara funció social: la d'oferir respostes a interrogants que inquieten socialment, no només els 'experts' de les ciències de l'educació, sinó la ciutadania en general, dins la qual s'inclouen evidentment pares i mares d'adolescents i el professorat mateix. Presentem en les pàgines següents un conjunt de reflexions que s'extreuen d'una recerca realitzada a dos instituts d'ensenyament secundari d'una ciutat mitjana de l'àrea metropolitana de Barcelona els anys 2000 i 2001
Pomace Olive Oil Concentrated in Triterpenic Acids Restores Vascular Function, Glucose Tolerance and Obesity Progression in Mice
Pomace olive oil, an olive oil sub-product, is a promising source of bioactive triterpenoids such as oleanolic acid and maslinic acid. Considering the vascular actions of pomace olive oil and the potential effects of the isolated oleanolic acid on metabolic complications of obesity, this study investigates for the first time the dietary intervention with a pomace olive oil with high concentrations of the triterpenic acids (POCTA), oleanolic and maslinic acid, during diet-induced obesity in mice. The results demonstrate that obese mice, when switched to a POCTA-diet for 10 weeks, show a substantial reduction of body weight, insulin resistance, adipose tissue inflammation, and particularly, improvement of vascular function despite high caloric intake. This study reveals the potential of a functional food based on pomace olive oil and its triterpenic fraction against obesity progression. Our data also contribute to understanding the health-promoting effects attributable to the Mediterranean dietSpanish Ministerio de Economía, Industria y Competitividad (MINECO), Agencia Estatal de Investigación (AEI), and Fondo Europeo de Desarrollo Regional (FEDER) (Grants SAF2017-82813-C3-3-R and PCI2018-092997/AEI to R.R.-R.
A Legal and Forensic Medicine Approach to Police Physical Intervention Techniques in High-Risk Situations
Background: The physical intervention techniques (PITs) typically used by the police in troublesome situations are examined in terms of injuring potential depending on whether they target a body zone of high, medium or low vulnerability. Based on legal and forensic considerations, and principles of congruence, opportunity and proportionality, a need exists to favor opponent locking and arrest techniques targeting non-vulnerable zones to minimize the risk of severe damage. Methods: A search of the training manuals for the different kind of law of enforcement officers was carried out. Revision of injuries was available from electronic databases of academic o medical journals. Results: Three different locking and arrest PITs based on operational tactical procedures (OTP) that avoid zones of high or medium vulnerability are proposed. The new techniques use blocking, diverting and grabbing of the upper and lower limbs, followed by dislocation and locking of the same targets. Conclusions: The damaging potential of such PITs was assessed in terms of anatomical region and most were found to have a high risk of severe damage. The alternative PITs proposed here, which rely on OTP, improve in legal and forensic medical terms on existing choices and dramatically reduce the risk of injuring arrestees
Empagliflozin reduces vascular damage and cognitive impairment in a mixed murine model of Alzheimer's disease and type 2 diabetes
Background Both Alzheimer's disease (AD) and type 2 diabetes (T2D) share common pathological features including inflammation, insulin signaling alterations, or vascular damage. AD has no successful treatment, and the close relationship between both diseases supports the study of antidiabetic drugs to limit or slow down brain pathology in AD. Empagliflozin (EMP) is a sodium-glucose co-transporter 2 inhibitor, the newest class of antidiabetic agents. EMP controls hyperglycemia and reduces cardiovascular comorbidities and deaths associated to T2D. Therefore, we have analyzed the role of EMP at the central level in a complex mouse model of AD-T2D. Methods We have treated AD-T2D mice (APP/PS1xdb/db mice) with EMP 10 mg/kg for 22 weeks. Glucose, insulin, and body weight were monthly assessed. We analyzed learning and memory in the Morris water maze and the new object discrimination test. Postmortem brain assessment was conducted to measure brain atrophy, senile plaques, and amyloid-beta levels. Tau phosphorylation, hemorrhage burden, and microglia were also measured in the brain after EMP treatment. Results EMP treatment helped to maintain insulin levels in diabetic mice. At the central level, EMP limited cortical thinning and reduced neuronal loss in treated mice. Hemorrhage and microglia burdens were also reduced in EMP-treated mice. Senile plaque burden was lower, and these effects were accompanied by an amelioration of cognitive deficits in APP/PS1xdb/db mice. Conclusions Altogether, our data support a feasible role for EMP to reduce brain complications associated to AD and T2D, including classical pathological features and vascular disease, and supporting further assessment of EMP at the central level
The elliptic model for communication fluxes
In this paper, a model (called the elliptic model) is proposed to estimate the number of social ties between two locations using population data in a similar manner to how transportation research deals with trips. To overcome the asymmetry of transportation models, the new model considers that the number of relationships between two locations is inversely proportional to the population in the ellipse whose foci are in these two locations. The elliptic model is evaluated by considering the anonymous communications patterns of 25 million users from three different countries, where a location has been assigned to each user based on their most used phone tower or billing zip code. With this information, spatial social networks are built at three levels of resolution: tower, city and region for each of the three countries. The elliptic model achieves a similar performance when predicting communication fluxes as transportation models do when predicting trips. This shows that human relationships are influenced at least as much by geography as is human mobility
Contrasting catastrophic eruptions predicted by different intrusion and collapse scenarios
Catastrophic volcanic eruptions triggered by landslide collapses can jet upwards or blast sideways. Magma intrusion is related to both landslide-triggered eruptive scenarios (lateral or vertical), but it is not clear how such different responses are produced, nor if any precursor can be used for forecasting them. We approach this problem with physical analogue modelling enhanced with X-ray Multiple Detector Computed Tomography scanning, used to track evolution of internal intrusion, and its related faulting and surface deformation. We find that intrusions produce three different volcano deformation patterns, one of them involving asymmetric intrusion and deformation, with the early development of a listric slump fault producing pronounced slippage of one sector. This previously undescribed early deep potential slip surface provides a unified explanation for the two different eruptive scenarios (lateral vs. vertical). Lateral blast only occurs in flank collapse when the intrusion has risen into the sliding block. Otherwise, vertical rather than lateral expansion of magma is promoted by summit dilatation and flank buttressing. The distinctive surface deformation evolution detected opens the possibility to forecast the possible eruptive scenarios: laterally directed blast should only be expected when surface deformation begins to develop oblique to the first major fault
Enantioselective C-P Bond Formation through C(sp3)-H Functionalization
An enantioselective C−P bond formation has been developed through a C(sp3)−H activation in an oxidation step followed by an organocatalyzed hydrophosphonylation protocol. The asymmetric organocatalytic Pudovik reaction has been achieved following a one‐pot strategy, starting from different benzylic and allylic alcohols and dibenzyl phosphite, using MnO2 as the oxidant and a chiral squaramide as organocatalyst. The scope of the reaction provides enantiomerically enriched α‐hydroxy phosphonates with yields from 40% to >95% and enantioselectivities from 64% to >99%. Furthermore, the use of this methodology has been demonstrated to form a tetrasubstituted carbon stereocenter, generating an acetophenone derivative in situ, using diphenyl phosphite. Therefore, this approach represents an asymmetric strategy for constructing chiral C−P bonds, which are of interest to the pharmaceutical industry
Remanence enhancement for stray field-based applications in arrays of crystalline nanomagnets
With the aim of achieving stable, substantial remanences adequate for exploitation in stray field-based applications, we report on the hysteresis behavior occurring in arrays of single-crystal Fe motifs, a-beam lithographed into prisms with triangular bases and different orientations of their magnetocrystalline axes with respect to the morphological symmetry axes. From both experimental and simulational analyses we recognize the fact that the magnetization reversal processes of our samples were mediated by motif-sized vortices. Their nucleation and annihilation fields and sites within the motifs, and their field-induced displacements, are discussed in terms of the magnetocrystalline and configurational anisotropies and inter-motif dipolar interactions. From our data, we conclude that reduced remanences as large as 0.85 (sufficient for the application requirements), protected by nucleation fields of several tens of Oe, can be produced in arrays where magnetocrystalline easy axes reinforce and partly compensate the easiest and hardest configurational ones, respectively. The angular dependence of the reduced remanence associated with interplay of these anisotropies corresponds to a symmetry reduction from the triaxial one linked to the triangular morphology down to an effective uniaxial one. We also identify, for the particular case of inter-nanoprism distances that are short in comparison with the dimensions of the motif base, a contribution to the remanence enhancement originating from the dipolar interactions
El trastorno neurótico de ansiedad, una mirada epidemiológica y afectiva actual
The present investigation was carried out with the aim of characterizing, from an epidemiological and emotional point of view, the patients with neurotic anxiety disorder in a sample formed by 50 patients between 25 to 55 years of age who attend the mental health community center of the Octavio de la Concepción y la Pedraja Teaching Polyclinic in Camajuani, Villa Clara province, during the period from January 2008 to February 2009. As main results of the study, it was determined that the highest incidence was found in the ages between 36 and 45 years with 58.0 percent; there was a prevalence of the female sex (68.0%), the marital status of divorced (54.0%), the pre-university educational level (40.0%), and the occupation of worker (48.0%). It was concluded that in the sample studied there were high levels of anxiety and stress which had as a common denominator the inadequacy between the expectations and the reality that the environment offers. That is why it is recommended to continue the current investigative line and expand the sampling design with the aim of finding psycho-educative strategies that could eliminate or lessen the negative emotional states and prolong the positive ones as predictors of psychological adjustment.La presente investigación se realizó con el objetivo de caracterizar desde el contexto epidemiológico y emocional a los pacientes con el trastorno neurótico de ansiedad en una muestra de 50 pacientes en el rango de edad entre los 25-55 años pertenecientes al Centro Comunitario de Salud Mental del Policlínico Docente “Octavio de la Concepción y la Pedraja” del Municipio Camajuaní, Provincia Villa Clara, en el período comprendido entre enero de 2008 a febrero de 2009. Como principales resultados en el estudio con relación al trastorno resultó la mayor cuantificación en el rango de edad de 36-45 años que registró el 58.0%, la prevalencia del sexo femenino (68.0%), el estado civil divorciado (54.0%), el nivel de escolaridad preuniversitario (40.0%) y la categoría ocupacional obrero (48.0%). Se concluye que en la muestra estudiada existieron niveles elevados de ansiedad y estrés, cuyo denominador común correspondió a la inadecuación entre las expectativas y la realidad que le ofrece el medio, por lo que recomendamos continuar la presente línea investigativa y ampliación de su diseño muestral encaminados a la búsqueda de estrategias psicoeducativas que permitan eliminar o atenuar los estados emocionales negativos y prolongar los positivos como predictores del ajuste psicológico
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