Pólos no gauge do cone de luz e o método de covariantização

Pós-graduação em Física - IFT

Mandelstam-leibbrandt: Not really a prescription in the light-cone gauge

Since the very beginning of it, perhaps the subtlest of all gauges is the light-cone gauge, for its implementation leads to characteristic singularities that require some kind of special prescription to handle them in a. proper and consistent manner. The best known of these prescriptions is the Mandelstam-Leibbrandt one. In this work we revisit it showing that its status as a mere prescription is not appropriate but rather that its origin can be traced back to fundamental physical properties such as causality and covariantization methods. © World Scientific Publishing Company.

A dynamical gluon mass solution in Mandelstam's approximation

We discuss the pure gauge Schwinger-Dyson equation for the gluon propagator in the Landau gauge within an approximation proposed by Mandelstam many years ago. We show that a dynamical gluon mass arises as a solution. This solution is obtained numerically in the full range of momenta that we have considered without the introduction of any ansatz or asymptotic expression in the infrared region. The vertex function that we use follows a prescription formulated by Cornwall to determine the existence of a dynamical gluon mass in the light cone gauge. The renormalization procedure differs from the one proposed by Mandelstam and allows for the possibility of a dynamical gluon mass. Some of the properties of this solution, such as its dependence on A(QCD) and its perturbative scaling behavior are also discussed.

Exercise-induced energy expenditure : implications for exercise prescription and obesity

Objective: Walking is commonly recommended to help with weight management. We measured total energy expenditure (TEE) and its components to quantify the impact of increasing exercise-induced energy expenditure (ExEE) on other components of TEE. Methods: Thirteen obese women underwent an 8-week walking group intervention. TEE was quantified using doubly labeled water, ExEE was quantified using heart rate monitors, daily movement was assessed by accelerometry and resting metabolic rate was measured using indirect calorimetry. Results: Four of the 13 participants achieved the target of 1500 kcal wk−1 of ExEE and all achieved 1000 kcal wk−1. The average ExEE achieved by the group across the 8 weeks was 1434 ± 237 kcal wk−1. Vigorous physical activity, as assessed by accelerometry, increased during the intervention by an average of 30 min per day. Non-exercise activity thermogenesis (NEAT) decreased, on average, by 175 kcal d−1 (−22%) from baseline to the intervention and baseline fitness was correlated with change in NEAT. Conclusions: Potential alterations in non-exercise activity should be considered when exercise is prescribed. The provision of appropriate education on how to self-monitor daily activity levels may improve intervention outcomes in groups who are new to exercise. Practice implications: Strategies to sustain incidental and light physical activity should be offered to help empower individuals as they develop and maintain healthy and long-lasting lifestyle habits.

Cardiac parasympathetic reactivation following exercise : implications for training prescription

The objective of exercise training is to initiate desirable physiological adaptations that ultimately enhance physical work capacity. Optimal training prescription requires an individualized approach, with an appropriate balance of training stimulus and recovery and optimal periodization. Recovery from exercise involves integrated physiological responses. The cardiovascular system plays a fundamental role in facilitating many of these responses, including thermoregulation and delivery/removal of nutrients and waste products. As a marker of cardiovascular recovery, cardiac parasympathetic reactivation following a training session is highly individualized. It appears to parallel the acute/intermediate recovery of the thermoregulatory and vascular systems, as described by the supercompensation theory. The physiological mechanisms underlying cardiac parasympathetic reactivation are not completely understood. However, changes in cardiac autonomic activity may provide a proxy measure of the changes in autonomic input into organs and (by default) the blood flow requirements to restore homeostasis. Metaboreflex stimulation (e.g. muscle and blood acidosis) is likely a key determinant of parasympathetic reactivation in the short term (0–90 min post-exercise), whereas baroreflex stimulation (e.g. exercise-induced changes in plasma volume) probably mediates parasympathetic reactivation in the intermediate term (1–48 h post-exercise). Cardiac parasympathetic reactivation does not appear to coincide with the recovery of all physiological systems (e.g. energy stores or the neuromuscular system). However, this may reflect the limited data currently available on parasympathetic reactivation following strength/resistance-based exercise of variable intensity. In this review, we quantitatively analyse post-exercise cardiac parasympathetic reactivation in athletes and healthy individuals following aerobic exercise, with respect to exercise intensity and duration, and fitness/training status. Our results demonstrate that the time required for complete cardiac autonomic recovery after a single aerobic-based training session is up to 24 h following low-intensity exercise, 24–48 h following threshold-intensity exercise and at least 48 h following high-intensity exercise. Based on limited data, exercise duration is unlikely to be the greatest determinant of cardiac parasympathetic reactivation. Cardiac autonomic recovery occurs more rapidly in individuals with greater aerobic fitness. Our data lend support to the concept that in conjunction with daily training logs, data on cardiac parasympathetic activity are useful for individualizing training programmes. In the final sections of this review, we provide recommendations for structuring training microcycles with reference to cardiac parasympathetic recovery kinetics. Ultimately, coaches should structure training programmes tailored to the unique recovery kinetics of each individual.

Nutrition prescription to achieve positive outcomes in Chronic Kidney Disease : a systematic review

In Chronic Kidney Disease (CKD), management of diet is important in prevention of disease progression and symptom management, however evidence on nutrition prescription is limited. Recent international CKD guidelines and literature was reviewed to address the following question “What is the appropriate nutrition prescription to achieve positive outcomes in adult patients with chronic kidney disease?” Databases included in the search were Medline and CINAHL using EBSCOhost search engine, Embase and the Cochrane Database of Systematic Reviews published from 2000 to 2009. International guidelines pertaining to nutrition prescription in CKD were also reviewed from 2000 to 2013. Three hundred and eleven papers and eight guidelines were reviewed by three reviewers. Evidence was graded as per the National Health and Medical Research Council of Australia criteria. The evidence from thirty six papers was tabulated under the following headings: protein, weight loss, enteral support, vitamin D, sodium, fat, fibre, oral nutrition supplements, nutrition counselling, including protein and phosphate, nutrients in peritoneal dialysis solution and intradialytic parenteral nutrition, and was compared to international guidelines. While more evidence based studies are warranted, the customary nutrition prescription remains satisfactory with the exception of Vitamin D and phosphate. In these two areas, additional research is urgently needed given the potential of adverse outcomes for the CKD patient.

Perception of prescription medicine sample packs among Australian professional, government, industry, and consumer organizations, based on automated textual analysis of one-on-one interviews

Background Prescription medicine samples provided by pharmaceutical companies are predominantly newer and more expensive products. The range of samples provided to practices may not represent the drugs that the doctors desire to have available. Few studies have used a qualitative design to explore the reasons behind sample use. Objective The aim of this study was to explore the opinions of a variety of Australian key informants about prescription medicine samples, using a qualitative methodology. Methods Twenty-three organizations involved in quality use of medicines in Australia were identified, based on the authors' previous knowledge. Each organization was invited to nominate 1 or 2 representatives to participate in semistructured interviews utilizing seeding questions. Each interview was recorded and transcribed verbatim. Leximancer v2.25 text analysis software (Leximancer Pty Ltd., Jindalee, Queensland, Australia) was used for textual analysis. The top 10 concepts from each analysis group were interrogated back to the original transcript text to determine the main emergent opinions. Results A total of 18 key interviewees representing 16 organizations participated. Samples, patient, doctor, and medicines were the major concepts among general opinions about samples. The concept drug became more frequent and the concept companies appeared when marketing issues were discussed. The Australian Pharmaceutical Benefits Scheme and cost were more prevalent in discussions about alternative sample distribution models, indicating interviewees were cognizant of budgetary implications. Key interviewee opinions added richness to the single-word concepts extracted by Leximancer. Conclusions Participants recognized that prescription medicine samples have an influence on quality use of medicines and play a role in the marketing of medicines. They also believed that alternative distribution systems for samples could provide benefits. The cost of a noncommercial system for distributing samples or starter packs was a concern. These data will be used to design further research investigating alternative models for distribution of samples.

Community pharmacy dispensing of prescription medicine sample packs: Changing the business of medicine initiation?

Prescription medicine samples (or starter packs) are provided by pharmaceutical manufacturers to prescribing doctors as one component in the suite of marketing products used to convince them to prescribe a particular medicine [1,2]. Samples are generally newer, more expensive treatment options still covered by patent [3,4]. Safe, effective, judicious and appropriate medicine use (quality use of medicines) [5] could be enhanced by involving community pharmacists in the dispensing of starter packs. Doctors who use samples show a trend towards prescribing more expensive medicines overall [6] and also prescribe more medicines [7]. Cardiovascular health and mental health are Australian National Health Priority Areas [8] and account for approximately 30% and 17%, respectively, of annual government Pharmaceutical Benefits System (PBS) in 2006 [9]. The PBS is Australia's universal prescription subsidy scheme [9]. Antihypertensives were a major contributor to the estimated 80 000 medicine-related hospital admissions in Australia in 1999 [10] and also internationally [11,12]. The aim of this study was to pilot an alternative model for supply of free sample or starter packs of prescription medicines and ascertain if it is a viable model in daily practice.

Secondary prevention of osteoporosis in Australia: Analysis of government-dispensed prescription data

Background Osteoporosis is a common cause of disability and death in elderly men and women. Until 2007, Australian Government-subsidized use of oral bisphosphonates, raloxifene and calcitriol (1α,25-dihydroxycholecalciferol) was limited to secondary prevention (requiring x-ray evidence of previous low-trauma fracture). The cost to the Pharmaceutical Benefits Scheme was substantial (164 million Australian dollars in 2005/6). Objective To examine the dispensed prescriptions for oral bisphosphonates, raloxifene, calcitriol and two calcium products for the secondary prevention of osteoporosis (after previous low-trauma fracture) in the Australian population. Methods We analysed government data on prescriptions for oral bisphosphonates, raloxifene, calcitriol and two calcium products from 1995 to 2006, and by sex and age from 2002 to 2006. Prescription counts were converted to defined daily doses (DDD)/1000 population/day. This standardized drug utilization method used census population data, and adjusts for the effects of aging in the Australian population. Results Total bisphosphonate use increased 460% from 2.19 to 12.26 DDD/1000 population/day between June 2000 and June 2006. The proportion of total bisphosphonate use in June 2006 was 75.1% alendronate, 24.6% risedronate and 0.3% etidronate. Raloxifene use in June 2006 was 1.32 DDD/1000 population/day. The weekly forms of alendronate and risedronate, introduced in 2001 and 2003, respectively, were quickly adopted. Bisphosphonate use peaked at age 80–89 years in females and 85–94 years in males, with 3-fold higher use in females than in males. Conclusions Pharmaceutical intervention for osteoporosis in Australia is increasing with most use in the elderly, the population at greatest risk of fracture. However, fracture prevalence in this population is considerably higher than prescribing of effective anti-osteoporosis medications, representing a missed opportunity for the quality use of medicines.

Antidepressant direct-to-consumer prescription drug advertising and public stigma of depression : the mediating role of perceived prevalence of depression

This study examines whether memory of antidepressant direct-to-consumer (DTC) prescription drug advertising is associated with the public stigma attached to depression. Results indicate that those who better remember antidepressant DTC ads tend to have a higher perceived prevalence of depression (i.e., more people suffer from depression). And, the perceived prevalence of depression is inversely associated with the public stigma toward depression. That is, those who have a higher perceived prevalence of depression report that they are more supportive of and comfortable with people who have depression. The results suggest that the perceived prevalence of depression is a mediating variable that accounts for the relationship between memory of antidepressant DTC ads and the public stigma toward depression. The implications and limitations of the study, as an exploratory investigation, are discussed.