916 resultados para Minimal path convexity
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A presymplectic structure for path-dependent Lagrangian systems is set up such that, when applied to ordinary Lagrangians, it yields the familiar Legendre transformation. It is then applied to derive a Hamiltonian formalism and the conserved quantities for those predictive invariant systems whose solutions also satisfy a Fokker-type action principle.
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A canonical formalism obtained for path-dependent Lagrangians is applied to Fokker-type Lagrangians. The results are specialized for coupling constant expansions and later on are applied to relativistic systems of particles interacting through symmetric scalar and vector mesodynamics and electrodynamics.
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The minimal replicon of the Pseudomonas plasmid pVS1 was genetically defined and combined with the Escherichia coli p15A replicon, to provide a series of new, oligocopy cloning vectors (5.3 to 8.3 kb). Recombinant plasmids derived from these vectors were stable in growing and nongrowing cells of root-colonizing P. fluorescens strains incubated under different environmental conditions for more than 1 month.
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The safe and responsible development of engineered nanomaterials (ENM), nanotechnology-based materials and products, together with the definition of regulatory measures and implementation of "nano"-legislation in Europe require a widely supported scientific basis and sufficient high quality data upon which to base decisions. At the very core of such a scientific basis is a general agreement on key issues related to risk assessment of ENMs which encompass the key parameters to characterise ENMs, appropriate methods of analysis and best approach to express the effect of ENMs in widely accepted dose response toxicity tests. The following major conclusions were drawn: Due to high batch variability of ENMs characteristics of commercially available and to a lesser degree laboratory made ENMs it is not possible to make general statements regarding the toxicity resulting from exposure to ENMs. 1) Concomitant with using the OECD priority list of ENMs, other criteria for selection of ENMs like relevance for mechanistic (scientific) studies or risk assessment-based studies, widespread availability (and thus high expected volumes of use) or consumer concern (route of consumer exposure depending on application) could be helpful. The OECD priority list is focussing on validity of OECD tests. Therefore source material will be first in scope for testing. However for risk assessment it is much more relevant to have toxicity data from material as present in products/matrices to which men and environment are be exposed. 2) For most, if not all characteristics of ENMs, standardized methods analytical methods, though not necessarily validated, are available. Generally these methods are only able to determine one single characteristic and some of them can be rather expensive. Practically, it is currently not feasible to fully characterise ENMs. Many techniques that are available to measure the same nanomaterial characteristic produce contrasting results (e.g. reported sizes of ENMs). It was recommended that at least two complementary techniques should be employed to determine a metric of ENMs. The first great challenge is to prioritise metrics which are relevant in the assessment of biological dose response relations and to develop analytical methods for characterising ENMs in biological matrices. It was generally agreed that one metric is not sufficient to describe fully ENMs. 3) Characterisation of ENMs in biological matrices starts with sample preparation. It was concluded that there currently is no standard approach/protocol for sample preparation to control agglomeration/aggregation and (re)dispersion. It was recommended harmonization should be initiated and that exchange of protocols should take place. The precise methods used to disperse ENMs should be specifically, yet succinctly described within the experimental section of a publication. 4) ENMs need to be characterised in the matrix as it is presented to the test system (in vitro/ in vivo). 5) Alternative approaches (e.g. biological or in silico systems) for the characterisation of ENMS are simply not possible with the current knowledge. Contributors: Iseult Lynch, Hans Marvin, Kenneth Dawson, Markus Berges, Diane Braguer, Hugh J. Byrne, Alan Casey, Gordon Chambers, Martin Clift, Giuliano Elia1, Teresa F. Fernandes, Lise Fjellsbø, Peter Hatto, Lucienne Juillerat, Christoph Klein, Wolfgang Kreyling, Carmen Nickel1, and Vicki Stone.
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BACKGROUND: We aimed to determine the smallest changes in health-related quality of life (HRQoL) scores in the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire core 30 and the Brain Cancer Module (QLQ-BN20), which could be considered as clinically meaningful in brain cancer patients. Materials and methods: World Health Organisation performance status (PS) and mini-mental state examination (MMSE) were used as clinical anchors appropriate to related subscales to determine the minimal clinically important differences (MCIDs) in HRQoL change scores (range 0-100) in the QLQ-C30 and QLQ-BN20. A threshold of 0.2 standard deviation (SD) (small effect) was used to exclude anchor-based MCID estimates considered too small to inform interpretation. RESULTS: Based on PS, our findings support the following integer estimates of the MCID for improvement and deterioration, respectively: physical (6, 9), role (14, 12), and cognitive functioning (8, 8); global health status (7, 4*), fatigue (12, 9), and motor dysfunction (4*, 5). Anchoring with MMSE, cognitive functioning MCID estimates for improvement and deterioration were (11, 2*) and for communication deficit were (9, 7). Estimates with asterisks were <0.2 SD and were excluded from our MCID range of 5-14. CONCLUSION: These estimates can help clinicians evaluate changes in HRQoL over time, assess the value of a health care intervention and can be useful in determining sample sizes in designing future clinical trials.
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We showed earlier how to predict the writhe of any rational knot or link in its ideal geometric configuration, or equivalently the average of the 3D writhe over statistical ensembles of random configurations of a given knot or link (Cerf and Stasiak 2000 Proc. Natl Acad. Sci. USA 97 3795). There is no general relation between the minimal crossing number of a knot and the writhe of its ideal geometric configuration. However, within individual families of knots linear relations between minimal crossing number and writhe were observed (Katritch et al 1996 Nature 384 142). Here we present a method that allows us to express the writhe as a linear function of the minimal crossing number within Conway families of knots and links in their ideal configuration. The slope of the lines and the shift between any two lines with the same
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Over the past decade a series of trials of the EORTC Brain Tumor Group (BTG) has substantially influenced and shaped the standard-of-care of primary brain tumors. All these trials were coupled with biological research that has allowed for better understanding of the biology of these tumors. In glioblastoma, EORTC trial 26981/22981 conducted jointly with the National Cancer Institute of Canada Clinical Trials Group showed superiority of concomitant radiochemotherapy with temozolomide over radiotherapy alone. It also identified the first predictive marker for benefit from alkylating agent chemotherapy in glioblastoma, the methylation of the O6-methyl-guanyl-methly-transferase (MGMT) gene promoter. In another large randomized trial, EORTC 26951, adjuvant chemotherapy in anaplastic oligodendroglial tumors was investigated. Despite an improvement in progression-free survival this did not translate into a survival benefit. The third example of a landmark trial is the EORTC 22845 trial. This trial led by the EORTC Radiation Oncology Group forms the basis for an expectative approach to patients with low-grade glioma, as early radiotherapy indeed prolongs time to tumor progression but with no benefit in overall survival. This trial is the key reference in deciding at what time in their disease adult patients with low-grade glioma should be irradiated. Future initiatives will continue to focus on the conduct of controlled trials, rational academic drug development as well as systematic evaluation of tumor tissue including biomarker development for personalized therapy. Important lessons learned in neurooncology are to dare to ask real questions rather than merely rapidly testing new compounds, and the value of well designed trials, including the presence of controls, central pathology review, strict radiology protocols and biobanking. Structurally, the EORTC BTG has evolved into a multidisciplinary group with strong transatlantic alliances. It has contributed to the maturation of neurooncology within the oncological sciences.
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The northeastern portion of the Mont Blanc massif in western Switzerland is predominantly comprised of the granitic rocks of the Mont Blanc intrusive suit, and the Mont Blanc basement gneisses. Within these metamorphic rocks are a variety of sub-economic Fe skarns. The mineral assemblages and fluid inclusions from these rocks have been used to derive age, pressure, temperature and fluid composition constraints for two Variscan events. Metamorphic hornblendes within the assemblages from the basement amphibolites and iron sk:lms have been dated using Ar-40/Ar-39, and indicate that these metamorphic events have a minimum age of approximately 334 Ma. Garnet-hornblende-plagioclase thermobarometry and stable isotope data obtained from the basement amphibolites are consistent with metamorphic temperatures in the range 515 to 580 degrees C, and pressures ranging from 5 to 8 kbar. Garnet-hornblende-magnetite thermobarometry and fluid inclusion studies indicate that the iron skarns formed at slightly lower temperatures, ranging from 400 to 500 degrees C in the presence of saline fluids at formational pressures similar to those experienced by the basement amphibolites. Late Paleozoic minimum uplift rates and geothermal gradients calculated using these data and the presence of Ladinien ichnofossils are on the order of 0.32 mm/year and 20 degrees C/km respectively. These uplift rates and geothermal gradients differ from those obtained from the neighbouring Aiguilles Rouges massif and indicate that these two massifs experienced different metamorphic conditions during the Carboniferous and Permian periods. During the early to late Carboniferous period the relative depths of the two massifs were reversed with the Aiguilles Rouges being initially unroofed at a much greater rate than the Mont Blanc, but experiencing relatively slower uplift rates near the termination of the Variscan orogeny.
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Total hip replacement has seen a tremendous development and has become one of the most successful surgical interventions in orthopaedics. While during the first decades of development of total hip arthroplasty the fixation of the implant into the bone was the main concern, the focus has shifted towards surgical technique and soft tissue handling. In order to avoid permanent soft tissue damage, muscular dysfunction and concerns in regards to cosmetics, minimal invasive and anatomic approaches have been developed. We here provide a short overview on various methods of total hip replacements and we describe our technique through a minimal invasive direct anterior approach. While muscle and nerve damage is minimal, this technique allows for a rapid rehabilitation and is associated with an excellent functional outcome and a minimal risk for dislocation.
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Abstract This paper presents the outcomes from a workshop of the European Network on the Health and Environmental Impact of Nanomaterials (NanoImpactNet). During the workshop, 45 experts in the field of safety assessment of engineered nanomaterials addressed the need to systematically study sets of engineered nanomaterials with specific metrics to generate a data set which would allow the establishment of dose-response relations. The group concluded that international cooperation and worldwide standardization of terminology, reference materials and protocols are needed to make progress in establishing lists of essential metrics. High quality data necessitates the development of harmonized study approaches and adequate reporting of data. Priority metrics can only be based on well-characterized dose-response relations derived from the systematic study of the bio-kinetics and bio-interactions of nanomaterials at both organism and (sub)-cellular levels. In addition, increased effort is needed to develop and validate analytical methods to determine these metrics in a complex matrix.