111 research outputs found
Fisher Renormalization for Logarithmic Corrections
For continuous phase transitions characterized by power-law divergences,
Fisher renormalization prescribes how to obtain the critical exponents for a
system under constraint from their ideal counterparts. In statistical
mechanics, such ideal behaviour at phase transitions is frequently modified by
multiplicative logarithmic corrections. Here, Fisher renormalization for the
exponents of these logarithms is developed in a general manner. As for the
leading exponents, Fisher renormalization at the logarithmic level is seen to
be involutory and the renormalized exponents obey the same scaling relations as
their ideal analogs. The scheme is tested in lattice animals and the Yang-Lee
problem at their upper critical dimensions, where predictions for logarithmic
corrections are made.Comment: 10 pages, no figures. Version 2 has added reference
Time in Quantum Mechanics and Quantum Field Theory
W. Pauli pointed out that the existence of a self-adjoint time operator is
incompatible with the semibounded character of the Hamiltonian spectrum. As a
result, people have been arguing a lot about the time-energy uncertainty
relation and other related issues. In this article, we show in details that
Pauli's definition of time operator is erroneous in several respects.Comment: 20 page
Human pancreatic islet transplantation: an update and description of the establishment of a pancreatic islet isolation laboratory
Type 1 diabetes mellitus (T1DM) is associated with chronic complications that lead to high morbidity and mortality rates in young adults of productive age. Intensive insulin therapy has been able to reduce the likelihood of the development of chronic diabetes complications. However, this treatment is still associated with an increased incidence of hypoglycemia. In patients with "brittle T1DM", who have severe hypoglycemia without adrenergic symptoms (hypoglycemia unawareness), islet transplantation may be a therapeutic option to restore both insulin secretion and hypoglycemic perception. The Edmonton group demonstrated that most patients who received islet infusions from more than one donor and were treated with steroid-free immunosuppressive drugs displayed a considerable decline in the initial insulin independence rates at eight years following the transplantation, but showed permanent C-peptide secretion, which facilitated glycemic control and protected patients against hypoglycemic episodes. Recently, data published by the Collaborative Islet Transplant Registry (CITR) has revealed that approximately 50% of the patients who undergo islet transplantation are insulin independent after a 3-year follow-up. Therefore, islet transplantation is able to successfully decrease plasma glucose and HbA1c levels, the occurrence of severe hypoglycemia, and improve patient quality of life. The goal of this paper was to review the human islet isolation and transplantation processes, and to describe the establishment of a human islet isolation laboratory at the Endocrine Division of the Hospital de ClÃnicas de Porto Alegre - Rio Grande do Sul, Brazil
Gendered dimensions of obesity in childhood and adolescence
BACKGROUND:
The literature on childhood and adolescent obesity is vast. In addition to producing a general overview, this paper aims to highlight gender differences or similarities, an area which has tended not to be the principal focus of this literature.
METHODS:
Databases were searched using the terms 'obesity' and 'child', 'adolescent', 'teenager', 'youth', 'young people', 'sex', 'gender', 'masculine', 'feminine', 'male', 'female', 'boy' and 'girl' (or variations on these terms). In order to limit the potential literature, the main focus is on other reviews, both general and relating to specific aspects of obesity.
RESULTS:
The findings of genetic studies are similar for males and females, and differences in obesity rates as defined by body mass index are generally small and inconsistent. However, differences between males and females due to biology are evident in the patterning of body fat, the fat levels at which health risks become apparent, levels of resting energy expenditure and energy requirements, ability to engage in certain physical activities and the consequences of obesity for the female reproductive system. Differences due to society or culture include food choices and dietary concerns, overall physical activity levels, body satisfaction and the long-term psychosocial consequences of childhood and adolescent obesity.
CONCLUSION:
This review suggests differences between males and females in exposure and vulnerability to obesogenic environments, the consequences of child and adolescent obesity, and responses to interventions for the condition. A clearer focus on gender differences is required among both researchers and policy makers within this field
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