Non-linear generalization of the sl(2) algebra

We present a generalization of the sl(2) algebra where the algebraic relations are constructed with the help of a general function of one of the generators. When this function is linear this algebra is a deformed sl(2) algebra. In the non-linear case, the finite dimensional representations are constructed in two different ways. In the first case, which provides finite dimensional representations only for the non-linear case, these representations come from solutions to a dynamical equation and we show how to construct explicitly these representations for a general quadratic non-linear function. The other type of finite dimensional representation comes from solutions to a cut condition equation. We give examples of solutions of this type in the non-linear case as well.Comment: 13 pages, 3 EPS figures, Late

Generalized quantum field theory: perturbative computation and perspectives

We analyze some consequences of two possible interpretations of the action of the ladder operators emerging from generalized Heisenberg algebras in the framework of the second quantized formalism. Within the first interpretation we construct a quantum field theory that creates at any space-time point particles described by a q-deformed Heisenberg algebra and we compute the propagator and a specific first order scattering process. Concerning the second one, we draw attention to the possibility of constructing this theory where each state of a generalized Heisenberg algebra is interpreted as a particle with different mass.Comment: 19 page

Cytotoxicity and antitumoral activity of dichloromethane extract and its fractions from Pothomorphe umbellata

The cytotoxicity of the dichloromethane crude extract (DCE), obtained from the aerial parts of Pothomorphe umbellata (L.) Miq (Piperaceae), was evaluated against nine human cancer cell lines (MCF-7, NCI-ADR/RES, OVCAR-3, PC-3, HT-29, NCI-H460, 786-O, UACC-62, K-562). The DCE presented antiproliferative activity with good potency against all cell lines at low concentrations (between 4.0 and 9.5 µg/mL) and with selectivity (1.55 µg/mL) for the leukemia cell line (K-652). DCE (100, 200, 300 and 400 mg/kg, ip) was also evaluated in the Ehrlich ascites tumor model. Both the survival number and the life span of the animals that died increased by at least 45 and 50%, respectively (8 animals per group), demonstrating P. umbellata extract potential anticancer activity. The results of the in vivo antitumor activity prompted the fractionation of the crude extract. The crude extract was submitted to dry column chromatography with dichloromethane-methanol (99:1). The column effluent fractions were extracted with methanol, dried under vacuum yielding fractions FR1 (less polar), FR2 (medium polarity), and FR3 (polar), which were analyzed for their growth inhibition or cytotoxic properties by a 48-h sulforhodamine B cell viability assay by measuring the total protein content. FR1 demonstrated high potency and cytotoxicity, a result compatible with the high toxicity of oxalic acid; FR2, containing 4-nerolidylcathecol, presented the lowest cytotoxic activity compared to the other two fractions but with selectivity for prostate cancer cell line; FR3, containing a mixture of steroids described in the literature as possessing various biological activities, also presented potent anticancer in vitro activity. These results suggest that P. umbellata DCE in vivo antitumor activity may be a consequence of the activity of different active principles.41141

Long-term effects of chronic cocaine exposure throughout adolescence on anxiety and stress responsivity in a wistar rat model

Adolescents display increased vulnerability to engage in drug experimentation. This is often considered a risk factor for later drug abuse. In this scenario, the permanent effects of cocaine exposure during adolescence on anxiety levels and stress responsivity, which may result in behavioral phenotypes prone to addiction, are now starting to be unveiled. Thus, the purpose of the present study was to evaluate the long-lasting effects of chronic cocaine administration during adolescence, on anxiety-like behavior and on stress response. Adolescent male Wistar rats were daily administered 45-mg cocaine/kg of body weight in three equal intraperitoneal doses with 1-h interval, from postnatal day (PND) 35 to 50. The effects of cocaine administration on anxiety levels, assessed in the Elevated Plus Maze (EPM), and on social stress response, assessed in the resident-intruder paradigm (R/I), were evaluated 10 days after withdrawal, when rats were reaching the adulthood. The underlying dopaminergic activity, and the corticosterone and testosterone levels were determined. Our results showed that cocaine induced long-lasting alterations in the hypothalamus-pituitary-adrenals (HPA) axis function and in testosterone levels. Such alterations resulted in significant and enduring changes in behavioral responses to environmental challenges, such as the EPM and R/I, including the evaluation of potential threats that may lead to high-risk behavior and low-benefit choices. This was further supported by an altered dopaminergic function in the amygdala and hippocampus. The present findings provide new insights into how the use of cocaine during adolescent development may modulate emotional behavior later in life. Compromised ability to recognize and deal with potential threats is an important risk factor to perpetuate compulsive drug seeking and relapse susceptibility.info:eu-repo/semantics/publishedVersio

Socioeconomic inequalities in dental health services in Sao Paulo, Brazil, 2003-2008

__Background:__ Access to, and use of, dental health services in Brazil have improved since 2003. The increase of private health care plans and the implementation of the "Smiling Brazil" Program, the largest public oral health care program in the world, could have influenced this increase in access. However, we do not yet know if inequalities in the use of dental health services persist after the improvement in access. The aims of this study are to analyze socioeconomic differences for dental health service use between 2003 and 2008 in São Paulo and to examine changes in these associations since the implementation of the Smiling Brazil program in 2003. __Method:__ Data was obtained via two household health surveys (ISA-Capital 2003 and ISA-Capital 2008) which investigated living conditions, lifestyle, health status and use of health care services. Logistic regression was used to analyze associations between socioeconomic factors and dental services use. Additionally, trends from 2003 to

Periodic orbit effects on conductance peak heights in a chaotic quantum dot

We study the effects of short-time classical dynamics on the distribution of Coulomb blockade peak heights in a chaotic quantum dot. The location of one or both leads relative to the short unstable orbits, as well as relative to the symmetry lines, can have large effects on the moments and on the head and tail of the conductance distribution. We study these effects analytically as a function of the stability exponent of the orbits involved, and also numerically using the stadium billiard as a model. The predicted behavior is robust, depending only on the short-time behavior of the many-body quantum system, and consequently insensitive to moderate-sized perturbations.Comment: 14 pages, including 6 figure

Risk factors for cluster seizures in canine idiopathic epilepsy

Cluster seizures (CS), two or more seizures within a 24-hour period, are reported in 38–77% of dogs with idiopathic epilepsy (IE). Negative outcomes associated with CS include a reduced likelihood of achieving seizure freedom, decreased survival time and increased likelihood of euthanasia. Previous studies have found factors including breed, sex and neuter status are associated with CS in dogs with IE; however, only one UK study in a multi-breed study of CS in IE patients exists to the author's knowledge, and thus further data is required to confirm these results. Data from 384 dogs treated at a multi-breed canine specific epilepsy clinic were retrospectively collected from electronic patient records. 384 dogs were included in the study, of which nearly half had a history of CS (49.1%). Dogs with a history of CS had a younger age at onset than those without (p = 0.033). In a multivariate model, three variables predicted risk of CS: a history of status epilepticus (p = 0.047), age at seizure onset (p = 0.066) and breed (German Shepherd Dog) (p < 0.001). Dogs with a history of status epilepticus and dogs with an older age at seizure onset were less likely to be affected by cluster seizures. German Shepherd Dogs (71% experiencing CS) were significantly more likely to suffer from CS compared to Labrador Retrievers (25%) (p < 0.001). There was no association between sex, neuter status, body size and CS. Further studies into the pathophysiology and genetics of CS are required to further understand this phenomenon

Use, access, and equity in health care services in São Paulo, Brazil

The study analyzed how socioeconomic factors are associated with seeking, access, use, and quality of health care services in São Paulo, Brazil. Data were obtained from two household health surveys in São Paulo. We used logistic regression to analyze associations between socioeconomic factors and seeking, access, use, and quality of health care services. Access to health care services was high among those who sought it (94.91% in 2003 and 94.98% in 2008). The proportion of access to and use of health care services did not change significantly from 2003 to 2008. Use of services in the public sector was more frequent in lower socioeconomic groups. There were some socioeconomic differences in seeking health care and resolution of health problems. The study showed almost universal access to health care services, but the results suggest problems in quality of services and differences in quality experienced by lower socioeconomic groups, who mostly use the Brazilian Unified National Health System (SUS)

Semiclassical Theory of Coulomb Blockade Peak Heights in Chaotic Quantum Dots

We develop a semiclassical theory of Coulomb blockade peak heights in chaotic quantum dots. Using Berry's conjecture, we calculate the peak height distributions and the correlation functions. We demonstrate that the corrections to the corresponding results of the standard statistical theory are non-universal and can be expressed in terms of the classical periodic orbits of the dot that are well coupled to the leads. The main effect is an oscillatory dependence of the peak heights on any parameter which is varied; it is substantial for both symmetric and asymmetric lead placement. Surprisingly, these dynamical effects do not influence the full distribution of peak heights, but are clearly seen in the correlation function or power spectrum. For non-zero temperature, the correlation function obtained theoretically is in good agreement with that measured experimentally.Comment: 5 color eps figure