Torsion and Gravitation: A new view

According to the teleparallel equivalent of general relativity, curvature and torsion are two equivalent ways of describing the same gravitational field. Despite equivalent, however, they act differently: whereas curvature yields a geometric description, in which the concept of gravitational force is absent, torsion acts as a true gravitational force, quite similar to the Lorentz force of electrodynamics. As a consequence, the right-hand side of a spinless-particle equation of motion (which would represent a gravitational force) is always zero in the geometric description, but not in the teleparallel case. This means essentially that the gravitational coupling prescription can be minimal only in the geometric case. Relying on this property, a new gravitational coupling prescription in the presence of curvature and torsion is proposed. It is constructed in such a way to preserve the equivalence between curvature and torsion, and its basic property is to be equivalent with the usual coupling prescription of general relativity. According to this view, no new physics is connected with torsion, which appears as a mere alternative to curvature in the description of gravitation. An application of this formulation to the equations of motion of both a spinless and a spinning particle is madeComment: To appear on IJMP

A Herschel Study of 24 micron-Selected AGNs and Their Host Galaxies

We present a sample of 290 24-micron-selected active galactic nuclei (AGNs) mostly at z ~ 0.3 -- 2.5, within 5.2 square degrees distributed as 25' X 25' fields around each of 30 galaxy clusters in the Local Cluster Substructure Survey (LoCuSS). The sample is nearly complete to 1 mJy at 24 microns, and has a rich multi-wavelength set of ancillary data; 162 are detected by Herschel. We use spectral templates for AGNs, stellar populations, and infrared emission by star forming galaxies to decompose the spectral energy distributions (SEDs) of these AGNs and their host galaxies, and estimate their star formation rates (SFRs), AGN luminosities, and host galaxy stellar masses. The set of templates is relatively simple: a standard Type-1 quasar template; another for the photospheric output of the stellar population; and a far infrared star-forming template. For the Type-2 AGN SEDs, we substitute templates including internal obscuration, and some Type-1 objects require a warm component (T > 50 K). The individually Herschel- detected Type-1 AGNs and a subset of 17 Type-2 ones typically have luminosities > 10^{45} ergs/s, and supermassive black holes of ~ 3 X 10^8 Msun emitting at ~ 10% of the Eddington rate. We find them in about twice the numbers of AGN identified in SDSS data in the same fields, i.e., they represent typical high luminosity AGN, not an infrared-selected minority. These AGNs and their host galaxies are studied further in an accompanying paper

Thrombus aspiration in patients with ST-elevation myocardial infarction: results of a national registry of interventional cardiology.

BACKGROUND: We aimed to evaluate the impact of thrombus aspiration (TA) during primary percutaneous coronary intervention (P-PCI) in 'real-world' settings. METHODS: We performed a retrospective study, using data from the National Registry of Interventional Cardiology (RNCI 2006-2012, Portugal) with ST-elevation myocardial infarction (STEMI) patients treated with P-PCI. The primary outcome, in-hospital mortality, was analysed through adjusted odds ratio (aOR) and 95% confidence intervals (95%CI). RESULTS: We assessed data for 9458 STEMI patients that undergone P-PCI (35% treated with TA). The risk of in-hospital mortality with TA (aOR 0.93, 95%CI:0.54-1.60) was not significantly decreased. After matching patients through the propensity score, TA reduced significantly the risk of in-hospital mortality (OR 0.58, 95%CI:0.35-0.98; 3500 patients). CONCLUSIONS: The whole cohort data does not support the routine use of TA in P-PCI, but the results of the propensity-score matched cohort suggests that the use of selective TA may improve the short-term risks of STEMI.info:eu-repo/semantics/publishedVersio

Population expansion in the North African Late Pleistocene signalled by mitochondrial DNA haplogroup U6

Background <br/> The archaeology of North Africa remains enigmatic, with questions of population continuity versus discontinuity taking centre-stage. Debates have focused on population transitions between the bearers of the Middle Palaeolithic Aterian industry and the later Upper Palaeolithic populations of the Maghreb, as well as between the late Pleistocene and Holocene. <br/> Results Improved resolution of the mitochondrial DNA (mtDNA) haplogroup U6 phylogeny, by the screening of 39 new complete sequences, has enabled us to infer a signal of moderate population expansion using Bayesian coalescent methods. To ascertain the time for this expansion, we applied both a mutation rate accounting for purifying selection and one with an internal calibration based on four approximate archaeological dates: the settlement of the Canary Islands, the settlement of Sardinia and its internal population re-expansion, and the split between haplogroups U5 and U6 around the time of the first modern human settlement of the Near East. <br/> Conclusions <br/> A Bayesian skyline plot placed the main expansion in the time frame of the Late Pleistocene, around 20 ka, and spatial smoothing techniques suggested that the most probable geographic region for this demographic event was to the west of North Africa. A comparison with U6's European sister clade, U5, revealed a stronger population expansion at around this time in Europe. Also in contrast with U5, a weak signal of a recent population expansion in the last 5,000 years was observed in North Africa, pointing to a moderate impact of the late Neolithic on the local population size of the southern Mediterranean coast

The relationships between portuguese banks and their customers in a recessionary context

Financial institutions were in the genesis of the crisis that led to the current recession. This study aims to understand better the relationship Portuguese people have with their banks in a recessionary context, as well as to provide knowledge that may contribute to the consumer behavior field of research linking to the Banking industry. Having that purpose in mind, a quantitative study was conducted using data gathered by questionnaire using a sample of 488 respondents, which was further complemented by the information collected applying Netnography. The overall analysis suggests that the impact of the crisis on the household financial situation throughout the last couple of years influences attitudes towards money and expenses. The way customers’ purchase and consumption behaviors were affected by crisis are, to some extent, positively related to their satisfaction with the main bank.info:eu-repo/semantics/publishedVersio

Online purchase determinants of loyalty: the mediating effect of satisfaction in tourism

The purpose of this research is to investigate the impact of four online purchase determinants (website image, routine, website knowledge and innovativeness) on customer loyalty and the mediating effect of customer satisfaction within the context of e-commerce. The research model is tested using data collected from 3188 regular buyers of the national leader in the sector being studied. The statistical analyses were conducted within the Structural Equation Modeling framework. Results show that there is a complete mediating effect of e-customer satisfaction in the relationship between three online purchase determinants (website image, online routine and website knowledge) and e-customer loyalty. The research results provide an important insight into how e-companies can pursuit and use delight to highlight customers' loyalty. These results allow for a better understanding of customer specificities, with practical actions aimed at their real needs and expectations.info:eu-repo/semantics/acceptedVersio

Biomassa microbiana do solo sob sistemas de manejo com diferentes coberturas vegetais.

bitstream/item/66226/1/31294.pdfOrganizado por: Alberto Feiden, Milton Parron Padovan, Adalgiza Inês Campolim, Aurélio Vinícius Borsato, Ivo de Sá Motta, João Batista Catto, Tércio Jacques Fehlaue

Vortices in the presence of a nonmagnetic atom impurity in 2D XY ferromagnets

Using a model of nonmagnetic impurity potential, we have examined the behavior of planar vortex solutions in the classical two-dimensional XY ferromagnets in the presence of a spin vacancy localized out of the vortex core. Our results show that a spinless atom impurity gives rise to an effective potential that repels the vortex structure.Comment: 6 pages, 2 figures, RevTex

VENOUS THROMBOEMBOLISM IN CHILDREN

Introdução: O tromboembolismo venoso é uma entidade rara em idade pediátrica, de etiologia multi-fatorial, sendo importante estabelecer o seu diagnóstico e avaliar o prognóstico funcional. Caso clínico: Adolescente de 11 anos, habitualmente saudável, observada no Serviço de Urgência por clínica compatível com trombose venosa superficial do membro superior. Da investigação realizada, controlo analítico incluindo velocidade de sedimentação, coagulação, auto-imunidade e homocisteína com valores dentro da normalidade. Efetuado estudo genético de trombofilias, apresentando mutação do gene da protrombina (G20210A, em heterozigotia) e mutações do PAI-1 (4G e -844A), associadas a estado de hipercoagulabilidade, com indicação para profilaxia com heparina de baixo peso molecular em situações de maior risco. Discussão/Conclusão: A raridade do evento tromboembólico, associada à localização atípica do quadro inaugural, conduziu a uma investigação exaustiva. As alterações da trombofilia podem ter a sua manifestação inicial na adolescência, sendo importante a sua deteção pelas implicações no dia-a-dia do indivíduo e necessidade de atitudes profiláticas em situações particulares.Introduction: Venous thromboembolism is rare among children and has a multi-factorial aetiology. It’s important to establish the diagnosis and evaluate the functional prognosis. Case report: A previously healthy 11 year old adolescent was observed in the emergency room with clinical signs of superficial venous thrombosis of the upper limb. Laboratorial evaluation showed a sedimentation rate, coagulation study, autoimmune antibodies and homocysteine with normal values. Testing for heritable thrombophilia revealed prothrombin mutation (G20210A, heterozigosity) and mutation of PAI-1 (4G e -844A), both of which are associated with hypercoagulable state and indication to do prophylaxis with low molecular weight heparin in higher risk situations. Discussion/Conclusion: The rarity of thromboembolic events at this age and the atypical localization lead to an exhaustive laboratorial evaluation. Thrombophilia mutations may clinically become evident in adolescence, and its detection is important because of children’s lifestyle and the need of prophylactic treatment in some situations