Gravitational collapse with tachyon field and barotropic fluid

A particular class of space-time, with a tachyon field, \phi, and a barotropic fluid constituting the matter content, is considered herein as a model for gravitational collapse. For simplicity, the tachyon potential is assumed to be of inverse square form i.e., V(\phi) \sim \phi^{-2}. Our purpose, by making use of the specific kinematical features of the tachyon, which are rather different from a standard scalar field, is to establish the several types of asymptotic behavior that our matter content induces. Employing a dynamical system analysis, complemented by a thorough numerical study, we find classical solutions corresponding to a naked singularity or a black hole formation. In particular, there is a subset where the fluid and tachyon participate in an interesting tracking behaviour, depending sensitively on the initial conditions for the energy densities of the tachyon field and barotropic fluid. Two other classes of solutions are present, corresponding respectively, to either a tachyon or a barotropic fluid regime. Which of these emerges as dominant, will depend on the choice of the barotropic parameter, \gamma. Furthermore, these collapsing scenarios both have as final state the formation of a black hole.Comment: 18 pages, 7 figures. v3: minor changes. Final version to appear in GR

Comorbidity in patients with diabetes mellitus: impact on medical health care utilization

BACKGROUND: Comorbidity has been shown to intensify health care utilization and to increase medical care costs for patients with diabetes. However, most studies have been focused on one health care service, mainly hospital care, or limited their analyses to one additional comorbid disease, or the data were based on self-reported questionnaires instead of health care registration data. The purpose of this study is to estimate the effects a broad spectrum of of comorbidities on the type and volume of medical health care utilization of patients with diabetes. METHODS: By linking general practice and hospital based registrations in the Netherlands, data on comorbidity and health care utilization of patients with diabetes (n = 7,499) were obtained. Comorbidity was defined as diabetes-related comorbiiabetes-related comorbidity. Multilevel regression analyses were applied to estimate the effects of comorbidity on health care utilization. RESULTS: Our results show that both diabetes-related and non diabetes-related comorbidity increase the use of medical care substantially in patients with diabetes. Having both diabeterelated and non diabetes-related comorbidity incrases the demand for health care even more. Differences in health care utilization patterns were observed between the comorbidities. CONCLUSION: Non diabetes-related comorbidity increases the health care demand as much as diabetes-related comorbidity. Current single-disease approach of integrated diabetes care should be extended with additional care modules, which must be generic and include multiple diseases in order to meet the complex health care demands of patients with diabetes in the future

Effects of non-steroidal anti-inflammatory drugs on cancer sites other than the colon and rectum: a meta-analysis

BACKGROUND: Observational studies have consistently shown that aspirin and non-steroidal anti-inflammatory drug (NSAID) use is associated with a close to 50% reduced risk of colorectal cancer. Studies assessing the effects of NSAIDs on other cancers have shown conflicting results. Therefore, we conducted a meta-analysis to evaluate the relationship between NSAID use and cancer other than colorectal. METHODS: We performed a search in Medline (from 1966 to 2002) and identified a total of 47 articles (13 cohort and 34 case-control studies). Overall estimates of the relative risk (RR) were calculated for each cancer site using random effects models. RESULTS: Aspirin use was associated with a reduced risk of cancer of the esophagus and the stomach (RR, 0.51; 95%CI (0.38–0.69), and 0.73; 95%CI (0.63–0.84)). Use of NSAIDs was similarly associated with a lower risk of esophageal and gastric cancers (RR,0.65; 95% CI(0.46–0.92) and RR,0.54; 95%CI (0.39–0.75)). Among other cancers, only the results obtained for breast cancer were fairly consistent in showing a slight reduced risk among NSAID and aspirin users (RR, 0.77; 95%CI (0.66–0.88), and RR, 0.77; 95%CI (0.69–0.86) respectively)). CONCLUSIONS: The results of this meta-analysis show that the potential chemopreventive role of NSAIDs in colorectal cancer might be extended to other gastrointestinal cancers such as esophagus and stomach. Further research is required to evaluate the role of NSAIDs at other cancers sites

Combined analgesics in (headache) pain therapy: shotgun approach or precise multi-target therapeutics?

<p>Abstract</p> <p>Background</p> <p>Pain in general and headache in particular are characterized by a change in activity in brain areas involved in pain processing. The therapeutic challenge is to identify drugs with molecular targets that restore the healthy state, resulting in meaningful pain relief or even freedom from pain. Different aspects of pain perception, i.e. sensory and affective components, also explain why there is not just one single target structure for therapeutic approaches to pain. A network of brain areas ("pain matrix") are involved in pain perception and pain control. This diversification of the pain system explains why a wide range of molecularly different substances can be used in the treatment of different pain states and why in recent years more and more studies have described a superior efficacy of a precise multi-target combination therapy compared to therapy with monotherapeutics.</p> <p>Discussion</p> <p>In this article, we discuss the available literature on the effects of several fixed-dose combinations in the treatment of headaches and discuss the evidence in support of the role of combination therapy in the pharmacotherapy of pain, particularly of headaches. The scientific rationale behind multi-target combinations is the therapeutic benefit that could not be achieved by the individual constituents and that the single substances of the combinations act together additively or even multiplicatively and cooperate to achieve a completeness of the desired therapeutic effect.</p> <p>As an example the fixesd-dose combination of acetylsalicylic acid (ASA), paracetamol (acetaminophen) and caffeine is reviewed in detail. The major advantage of using such a fixed combination is that the active ingredients act on different but distinct molecular targets and thus are able to act on more signalling cascades involved in pain than most single analgesics without adding more side effects to the therapy.</p> <p>Summary</p> <p>Multitarget therapeutics like combined analgesics broaden the array of therapeutic options, enable the completeness of the therapeutic effect, and allow doctors (and, in self-medication with OTC medications, the patients themselves) to customize treatment to the patient's specific needs. There is substantial clinical evidence that such a multi-component therapy is more effective than mono-component therapies.</p

The distinct roles of spirituality and religiosity in physical and mental health after collective trauma: a national longitudinal study of responses to the 9/11 attacks

Researchers have identified health implications of religiosity and spirituality but have rarely addressed differences between these dimensions. The associations of religiosity and spirituality with physical and mental health were examined in a national sample (N = 890) after the September 11, 2001 terrorist attacks (9/11). Health information was collected before 9/11 and health, religiosity, and spirituality were assessed longitudinally during six waves of data collection over the next 3 years. Religiosity (i.e., participation in religious social structures) predicted higher positive affect (β = .12), fewer cognitive intrusions (β = -.07), and lower odds of new onset mental (incidence rate ratio [IRR] = .88) and musculoskeletal (IRR = .94) ailments. Spirituality (i.e., subjective commitment to spiritual or religious beliefs) predicted higher positive affect (β = .09), lower odds of new onset infectious ailments (IRR = 0.83), more intrusions (β = .10) and a more rapid decline in intrusions over time (β = -.10). Religiosity and spirituality independently predict health after a collective trauma, controlling for pre-event health status; they are not interchangeable indices of religion

A comparison of alternative asymptotic frameworks to analyse a structural change in a linear time trend

This paper considers various asymptotic approximations to the finite sample distribution of the estimate of the break date in a simple one-break model for a linear trend function that exhibits a change in slope, with or without a concurrent change in intercept. The noise component is either stationary or has an autoregressive unit root. Our main focus is on comparing the so-called "bounded-trend" and "unbounded-trend" asymptotic frameworks. Not surprisingly, the "bounded-trend" asymptotic framework is of little use when the noise component is integrated. When the noise component is stationary, we obtain the following results. If the intercept does not change and is not allowed to change in the estimation, both frameworks yield the same approximation. However, when the intercept is allowed to change, whether or not it actually changes in the data, the "bounded-trend" asymptotic framework completely misses important features of the finite sample distribution of the estimate of the break date, especially the pronounced bimodality that was uncovered by Perron and Zhu (2005) and shown to be well captured using the "unbounded-trend" asymptotic framework. Simulation experiments confirm our theoretical findings, which expose the drawbacks of using the " bounded-trend" asymptotic framework in the context of structural change models. Copyright Royal Economic Society 2006