1,105 research outputs found
Gravitational Radiation from Post-Newtonian Sources and Inspiralling Compact Binaries
The article reviews the current status of a theoretical approach to the
problem of the emission of gravitational waves by isolated systems in the
context of general relativity. Part A of the article deals with general
post-Newtonian sources. The exterior field of the source is investigated by
means of a combination of analytic post-Minkowskian and multipolar
approximations. The physical observables in the far-zone of the source are
described by a specific set of radiative multipole moments. By matching the
exterior solution to the metric of the post-Newtonian source in the near-zone
we obtain the explicit expressions of the source multipole moments. The
relationships between the radiative and source moments involve many non-linear
multipole interactions, among them those associated with the tails (and
tails-of-tails) of gravitational waves. Part B of the article is devoted to the
application to compact binary systems. We present the equations of binary
motion, and the associated Lagrangian and Hamiltonian, at the third
post-Newtonian (3PN) order beyond the Newtonian acceleration. The
gravitational-wave energy flux, taking consistently into account the
relativistic corrections in the binary moments as well as the various tail
effects, is derived through 3.5PN order with respect to the quadrupole
formalism. The binary's orbital phase, whose prior knowledge is crucial for
searching and analyzing the signals from inspiralling compact binaries, is
deduced from an energy balance argument.Comment: 109 pages, 1 figure; this version is an update of the Living Review
article originally published in 2002; available on-line at
http://www.livingreviews.org
Vitamin D supplementation and breast cancer prevention : a systematic review and meta-analysis of randomized clinical trials
In recent years, the scientific evidence linking vitamin D status or supplementation to breast cancer has grown notably. To investigate the role of vitamin D supplementation on breast cancer incidence, we conducted a systematic review and meta-analysis of randomized controlled trials comparing vitamin D with placebo or no treatment. We used OVID to search MEDLINE (R), EMBASE and CENTRAL until April 2012. We screened the reference lists of included studies and used the “Related Article” feature in PubMed to identify additional articles. No language restrictions were applied. Two reviewers independently extracted data on methodological quality, participants, intervention, comparison and outcomes. Risk Ratios and 95% Confident Intervals for breast cancer were pooled using a random-effects model. Heterogeneity was assessed using the I2 test. In sensitivity analysis, we assessed the impact of vitamin D dosage and mode of administration on treatment effects. Only two randomized controlled trials fulfilled the pre-set inclusion criteria. The pooled analysis included 5372 postmenopausal women. Overall, Risk Ratios and 95% Confident Intervals were 1.11 and 0.74–1.68. We found no evidence of heterogeneity. Neither vitamin D dosage nor mode of administration significantly affected breast cancer risk. However, treatment efficacy was somewhat greater when vitamin D was administered at the highest dosage and in combination with calcium (Risk Ratio 0.58, 95% Confident Interval 0.23–1.47 and Risk Ratio 0.93, 95% Confident Interval 0.54–1.60, respectively). In conclusions, vitamin D use seems not to be associated with a reduced risk of breast cancer development in postmenopausal women. However, the available evidence is still limited and inadequate to draw firm conclusions. Study protocol code: FARM8L2B5L
International Veterinary Epilepsy Task Force Consensus Proposal: Diagnostic approach to epilepsy in dogs
This article outlines the consensus proposal on diagnosis of epilepsy in dogs by the International Veterinary Epilepsy Task Force. The aim of this consensus proposal is to improve consistency in the diagnosis of epilepsy in the clinical and research settings. The diagnostic approach to the patient presenting with a history of suspected epileptic seizures incorporates two fundamental steps: to establish if the events the animal is demonstrating truly represent epileptic seizures and if so, to identify their underlying cause. Differentiation of epileptic seizures from other non-epileptic episodic paroxysmal events can be challenging. Criteria that can be used to make this differentiation are presented in detail and discussed. Criteria for the diagnosis of idiopathic epilepsy (IE) are described in a three-tier system. Tier I confidence level for the diagnosis of IE is based on a history of two or more unprovoked epileptic seizures occurring at least 24 h apart, age at epileptic seizure onset of between six months and six years, unremarkable inter-ictal physical and neurological examination, and no significant abnormalities on minimum data base blood tests and urinalysis. Tier II confidence level for the diagnosis of IE is based on the factors listed in tier I and unremarkable fasting and post-prandial bile acids, magnetic resonance imaging (MRI) of the brain (based on an epilepsy-specific brain MRI protocol) and cerebrospinal fluid (CSF) analysis. Tier III confidence level for the diagnosis of IE is based on the factors listed in tier I and II and identification of electroencephalographic abnormalities characteristic for seizure disorders. The authors recommend performing MRI of the brain and routine CSF analysis, after exclusion of reactive seizures, in dogs with age at epileptic seizure onset 6 years, inter-ictal neurological abnormalities consistent with intracranial neurolocalisation, status epilepticus or cluster seizure at epileptic seizure onset, or a previous presumptive diagnosis of IE and drug-resistance with a single antiepileptic drug titrated to the highest tolerable dose
Surface and Temporal Biosignatures
Recent discoveries of potentially habitable exoplanets have ignited the
prospect of spectroscopic investigations of exoplanet surfaces and atmospheres
for signs of life. This chapter provides an overview of potential surface and
temporal exoplanet biosignatures, reviewing Earth analogues and proposed
applications based on observations and models. The vegetation red-edge (VRE)
remains the most well-studied surface biosignature. Extensions of the VRE,
spectral "edges" produced in part by photosynthetic or nonphotosynthetic
pigments, may likewise present potential evidence of life. Polarization
signatures have the capacity to discriminate between biotic and abiotic "edge"
features in the face of false positives from band-gap generating material.
Temporal biosignatures -- modulations in measurable quantities such as gas
abundances (e.g., CO2), surface features, or emission of light (e.g.,
fluorescence, bioluminescence) that can be directly linked to the actions of a
biosphere -- are in general less well studied than surface or gaseous
biosignatures. However, remote observations of Earth's biosphere nonetheless
provide proofs of concept for these techniques and are reviewed here. Surface
and temporal biosignatures provide complementary information to gaseous
biosignatures, and while likely more challenging to observe, would contribute
information inaccessible from study of the time-averaged atmospheric
composition alone.Comment: 26 pages, 9 figures, review to appear in Handbook of Exoplanets.
Fixed figure conversion error
International Veterinary Epilepsy Task Force consensus proposal: Medical treatment of canine epilepsy in Europe
In Europe, the number of antiepileptic drugs (AEDs) licensed for dogs has grown considerably over the last years. Nevertheless, the same questions remain, which include, 1) when to start treatment, 2) which drug is best used initially, 3) which adjunctive AED can be advised if treatment with the initial drug is unsatisfactory, and 4) when treatment changes should be considered. In this consensus proposal, an overview is given on the aim of AED treatment, when to start long-term treatment in canine epilepsy and which veterinary AEDs are currently in use for dogs. The consensus proposal for drug treatment protocols, 1) is based on current published evidence-based literature, 2) considers the current legal framework of the cascade regulation for the prescription of veterinary drugs in Europe, and 3) reflects the authors’ experience. With this paper it is aimed to provide a consensus for the management of canine idiopathic epilepsy. Furthermore, for the management of structural epilepsy AEDs are inevitable in addition to treating the underlying cause, if possible
Simple Metals at High Pressure
In this lecture we review high-pressure phase transition sequences exhibited
by simple elements, looking at the examples of the main group I, II, IV, V, and
VI elements. General trends are established by analyzing the changes in
coordination number on compression. Experimentally found phase transitions and
crystal structures are discussed with a brief description of the present
theoretical picture.Comment: 22 pages, 4 figures, lecture notes for the lecture given at the Erice
course on High-Pressure Crystallography in June 2009, Sicily, Ital
Papillary thyroid cancer associated with syndrome of inappropriate antidiuresis: a case report
<p>Abstract</p> <p>Introduction</p> <p>The syndrome of inappropriate antidiuresis is the most common cause of euvolemic hypo-osmolality. This syndrome is associated with a wide variety of diseases. However, its most frequent causes are related to malignancies, especially lung cancer. In this case report, we describe an unknown association of the syndrome of inappropriate antidiuresis with papillary thyroid cancer.</p> <p>Case presentation</p> <p>We present the case of a 71-year-old Caucasian, German woman with marked hyponatremia and neurological symptoms. After a detailed clinical investigation, the common causes of syndrome of inappropriate antidiuresis and other malignancies were ruled out. A thyroid nodule was detected by ultrasound and magnetic resonance imaging. Although fine needle aspiration cytology showed negative results, our patient underwent surgery. Papillary thyroid cancer was later diagnosed. After total thyroidectomy, a complete remission of the clinical symptoms occurred and our patient subsequently had iodine-131 radioactive therapy. Hyponatremia was no longer observed during the follow-up investigations.</p> <p>Conclusion</p> <p>This is the first reported case of paraneoplastic syndrome of inappropriate antidiuresis caused by papillary thyroid carcinoma. Since its symptoms occurred before the development of local symptoms, total thyroidectomy may provide a timely and efficient treatment for the underlying malignancy.</p
Evaluation of arterial anatomy in congenital clubfoot with color doppler ultrasound
OBJECTIVE: This investigation intended to evaluate anterior and posterior tibial arteries at the ankle joint level in congenital clubfoot, by using color Doppler ultrasound (CDU). MATERIAL AND METHOD: Twenty patients with idiopathic clubfoot were selected, from which 18 had unilateral involvement and two had bilateral involvement. Of the 18 patients with unilateral clubfoot, 16 went through surgical treatment and the other two were submitted to conservative treatment with serial casting. Of the bilateral cases, one patient was treated surgically and the other was treated with serial casting. All patients were clinically and radiographically assessed. We used the functional rating as described by Lehman. Then, CDU was applied bilaterally at the ankle joint level, trying to identify both posterior and anterior tibial arteries. RESULTS: In our present series of 20 cases with idiopathic clubfoot, in just one patient we could not identify the anterior tibial artery at the ankle joint level. In 12 patients who have had their arterial flow speeds and diameters measured by UDC, a positive correlation was found between functional level and anterior tibial artery diameter. No statistically significant differences were found between both flow speed and diameter of anterior tibial artery of the normal side, when compared to the affected side (in patients with unilateral disease). CONCLUSION: In our sample, we could not find any significant differences in arterial morphology and flow speed between the normal and the affected side. Furthermore, we noticed that the better the clinical result of clubfoot correction, the larger the diameter of anterior tibial artery in affected feet.OBJETIVO: Avaliação ultrassonográfica das artérias tibial anterior e posterior no pé torto congênito (PTC). MATERIAL E MÉTODO: Foram incluídos 20 pacientes portadores de PTC idiopático compreendendo 18 casos unilaterais e dois bilaterais, sendo que 17 pacientes foram submetidos a tratamento cirúrgico e três a tratamento conservador. Todos os pacientes apresentavam pés plantígrados e foram submetidos à avaliação clínica e radiográfica, seguido pelo exame de ultrassom Doppler colorido (UDC), visando a identificação das artérias tibiais anterior e posterior na altura do tornozelo. O nível funcional foi classificado pelos critérios de Lehman. RESULTADOS: Nesta série de 20 pacientes, somente em um não foi identificada a artéria tibial anterior. Nos 12 pacientes submetidos à mensuração de fluxo e calibre pelo UDC, foi encontrada uma correlação positiva entre o grau funcional do PTC e o calibre da artéria tibial anterior. Não houve redução estatisticamente significante entre o fluxo e calibre da artéria tibial anterior do lado normal em comparação com o lado alterado (nos casos de doença unilateral). CONCLUSÕES: Não houve alteração significativa da morfologia e fluxo arterial quando comparamos os lados afetado e normal. Além disso, quanto melhor o resultado clínico da correção do PTC, maior foi o calibre da artéria tibial anterior.UNIFESP Departamento de Ortopedia e TraumatologiaUNIFESP, Depto. de Ortopedia e TraumatologiaSciEL
Context-sensitive autoassociative memories as expert systems in medical diagnosis
BACKGROUND: The complexity of our contemporary medical practice has impelled the development of different decision-support aids based on artificial intelligence and neural networks. Distributed associative memories are neural network models that fit perfectly well to the vision of cognition emerging from current neurosciences. METHODS: We present the context-dependent autoassociative memory model. The sets of diseases and symptoms are mapped onto a pair of basis of orthogonal vectors. A matrix memory stores the associations between the signs and symptoms, and their corresponding diseases. A minimal numerical example is presented to show how to instruct the memory and how the system works. In order to provide a quick appreciation of the validity of the model and its potential clinical relevance we implemented an application with real data. A memory was trained with published data of neonates with suspected late-onset sepsis in a neonatal intensive care unit (NICU). A set of personal clinical observations was used as a test set to evaluate the capacity of the model to discriminate between septic and non-septic neonates on the basis of clinical and laboratory findings. RESULTS: We show here that matrix memory models with associations modulated by context can perform automatic medical diagnosis. The sequential availability of new information over time makes the system progress in a narrowing process that reduces the range of diagnostic possibilities. At each step the system provides a probabilistic map of the different possible diagnoses to that moment. The system can incorporate the clinical experience, building in that way a representative database of historical data that captures geo-demographical differences between patient populations. The trained model succeeds in diagnosing late-onset sepsis within the test set of infants in the NICU: sensitivity 100%; specificity 80%; percentage of true positives 91%; percentage of true negatives 100%; accuracy (true positives plus true negatives over the totality of patients) 93,3%; and Cohen's kappa index 0,84. CONCLUSION: Context-dependent associative memories can operate as medical expert systems. The model is presented in a simple and tutorial way to encourage straightforward implementations by medical groups. An application with real data, presented as a primary evaluation of the validity and potentiality of the model in medical diagnosis, shows that the model is a highly promising alternative in the development of accuracy diagnostic tools
- …