967 resultados para rigorous results in statistical mechanics


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The distribution limits of Crocidura russula (Hermann, 1780) and C. leucodon (Hermann, 1780) were investigated during an interval of 25 years in the bottom of the Rhone valley above Lake Geneva, Switzerland (total data set: 105 spatio-temporal occurrences, 1137 shrews). In 1975, the contact zone between the two species was situated in the region of Martigny. In 1999/2000, new sampling revealed three results: (1) The contact zone showed an upward shift of about 25 km. (2) In the expanded range of C. russula, the resident species has totally disappeared (confirmed by owl pellets analysis). (3) This demonstrates a dominance of C, russula over C. leucodon. Three hypotheses which may explain the range expansion of C. russula were evaluated: (1) habitat modification favouring linear dispersal due to the construction of a highway; (2) temporal event favoured by climate fluctuations, or (3) ongoing postglacial colonisation of Europe. Hypothesis 1 was rejected, because the progression of the shrews anticipated the construction. Hypothesis 3 received only weak support because range limits of C. russula in the region of Nice have been stable for thousands of years. Therefore hypothesis 2, admitting that ongoing climate change has facilitated range expansion, is the most probable.

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INTRODUCTION: This is a single, level 1 trauma centre, prospective consecutive patient series with intramedullary infection in the presence of unstable tibial fracture treated using the Kirschner wire-reinforced, antibiotic cement nail. PATIENTS AND METHODS: A total of 10 consecutive patients (eight males and two females) with a mean age of 42 years (range, 20-59) suffering from infection after intramedullary nailing for tibial fracture, admitted during a period of 4 years, were included. An antibiotic cement-coated nail, handmade at the time of surgery, was implanted in all patients. This was followed by a standardised 6-week treatment protocol, extraction of the nail and definitive fixation. RESULTS: At 6 years of follow-up, infection eradication and bony union were possible in all of the patients. No further infection treatment was necessary; however, all of our patients underwent additional procedures (mean: four additional procedures per patient) for cosmetic or other non-infectious reasons (bone grafting, muscle flaps, etc.). CONCLUSIONS: The antibiotic cement-coated nail seems to be an effective treatment for intramedullary infections of the fractured tibia.

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Based on data available in the Information System for Notifiable Diseases, predictive factors of favorable results were identified in the treatment of pulmonary tuberculosis, diagnosed between 2001 and 2004 and living in Recife-PE, Brazil. Uni- and multivariate logistic regression methods were used. In multivariate analysis, the following factors remained: Age (years), 0 to 9 (OR=4.27; p=0.001) and 10 to 19 (OR=1.78; p=0.011), greater chance of cure than over 60; Education (years), 8 to 11 (OR=1.52; p=0.049), greater chance of cure than no education; Type of entry, new cases (OR=3.31; p<0.001) and relapse (OR=3.32; p<0.001), greater chances of cure than restart after abandonment; Time (months) 2, 5-|6 (OR=9.15; p<0.001); 6-|9 (OR=27.28; p<0.001) and More than 9 (OR=24.78; p<0.001), greater chances of cure than less than 5; Health Unit District, DS I (OR=1.60; p=0.018) and DS IV (OR=2.87; p<0.001), greater chances of cure than DS VI.

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The aim of this thesis is to present a solution to the quantum phase problem of the single-mode optical field. The solution is based on the use of phase shift covariant normalized positive operator measures. These measures describe realistic direct coherent state phase measurements such as the phase measurement schemes based on eight-port homodyne detection or heterodyne detection. The structure of covariant operator measures and, more generally, covariant sesquilinear form measures is analyzed in this work. Four different characterizations for phase shift covariant normalized positive operator measures are presented. The canonical covariant operator measure is definded and its properties are studied. Finally, some other suggested phase theories are introduced to investigate their connections to the covariant sesquilinear form measures.

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Aim: The management of large lesions of the skull base, such as vestibular schwanommas (VS), meningiomas (MEN) or pituitary adenomas (PA), is challenging, with microsurgery remaining the main treatment option. Planned subtotal resection is now being increasingly considered to reduce the risk of neurological deficits following complete resection. The residual part of the tumor can then be treated with Gamma Knife Radiosurgery (GKR) to achieve long-term growth control. Methods: This case series documents early results with planned subtotal resection followed by GKR in Lausanne University Hospital, between July 2010 and March 2012. There were 24 patients who underwent surgery, with 22 having already undergone GKR and 2 waiting for GKR. We analyzed clinical symptoms for all patients, as well as audiograms, ophthalmological and endocrinological tests, when indicated. Results: Nine patients had VS surgery (mean diameter 35 mm; range 30-44.5) through a retrosigmoid approach. There were no post-operative facial nerve deficits. Of the 3 patients whom had useful hearing pre-operatively, this improved in 2 and remained stable in 1. Four patients with clinoid MEN (mean diameter 26.5 mm; range 17-42) underwent subtotal resection of the tumor, and the component in the cavernous sinus was later treated with GKR. The visual status remained stable in 3 patients and one had complete visual recovery. 4 patients underwent subtotal resection of petro-clival MEN (mean diameter 36 mm; range 32-42): 3 had House-Brackmann (HB) grade 2 facial function that recovered completely; one continues to have HB grade 4 facial deficit following surgery. Of the 7 patients with PA (mean diameter 34.5 mm; range 20-54.5), 2 had acromegaly, the others were non functional PA. Six patients underwent trans-sphenoidal surgery, while one patient had a transcavernous sinus resection of the tumor (with prior staged trans-sphenoidal surgery). Visual status improved in 3 patients while the others remained stable. Two patients had transient diabetes insipidus following surgery. Up to now, no additional deficit or worsening has been reported after GKR. Conclusions: Our data suggest that planned subtotal resection has an excellent clinical outcome with respect to preservation of cranial nerves, and other neurological functions, and a good possibility of recovery of many of the pre-operative cranial nerve dysfunctions. The results in terms of tumor control following GKR need further long-term evaluation.

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We are interested in the development, implementation and testing of an orthotropic model for cardiac contraction based on an active strain decomposition. Our model addresses the coupling of a transversely isotropic mechanical description at the cell level, with an orthotropic constitutive law for incompressible tissue at the macroscopic level. The main differences with the active stress model are addressed in detail, and a finite element discretization using Taylor-Hood and MINI elements is proposed and illustrated with numerical examples.

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Memo is a widely expressed 33-kDa protein required for heregulin (HRG)-, epidermal growth factor (EGF)-, and fibroblast growth factor (FGF)-induced cell motility. Studies in mouse embryonic fibroblasts, wild-type or knockout for Memo, were performed to further investigate the role of Memo downstream of FGFR. We demonstrated that Memo associates with the FGFR signalosome and is necessary for optimal activation of signaling. To uncover Memo's physiological role, Memo conditional-knockout mice were generated. These animals showed a reduced life span, increased insulin sensitivity, small stature, graying hair, alopecia, kyphosis, loss of subcutaneous fat, and loss of spermatozoa in the epididymis. Memo-knockout mice also have elevated serum levels of active vitamin D, 1,25-dihydroxyvitamin D3 (1,25(OH)2D), and calcium compared to control littermates expressing Memo. In summary, the results from in vivo and in vitro models support the hypothesis that Memo is a novel regulator of FGFR signaling with a role in controlling 1,25(OH)2D production and normal calcium homeostasis.

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AIMS: Retroviral-mediated gene therapy has been proposed as a primary or adjuvant treatment for advanced cancer, because retroviruses selectively infect dividing cells. Efficacy of retroviral-mediated gene transfer, however, is limited in vivo. Although packaging cell lines can produce viral vectors continuously, such allo- or xenogeneic cells are normally rejected when used in vivo. Encapsulation using microporous membranes can protect the packaging cells from rejection. In this study, we used an encapsulated murine packaging cell line to test the effects of in situ delivery of a retrovirus bearing the herpes simplex virus thymidine kinase suicide gene in a rat model of orthotopic glioblastoma. MATERIALS AND METHODS: To test gene transfer in vitro, encapsulated murine psi2-VIK packaging cells were co-cultured with baby hamster kidney (BHK) cells, and the percentage of transfected BHK cells was determined. For in vivo experiments, orthotopic C6 glioblastomas were established in Wistar rats. Capsules containing psi2-VIK cells were stereotaxically implanted into these tumours and the animals were treated with ganciclovir (GCV). Tumours were harvested 14 days after initiation of GCV therapy for morphometric analysis. RESULTS: Encapsulation of psi2-VIK cells increased transfection rates of BHK target cells significantly in vitro compared to psi2-VIK conditioned medium (3 x 10(6) vs 2.3 x 10(4) cells; P<0.001). In vivo treatment with encapsulated packaging cells resulted in 3% to 5% of C6 tumour cells transduced and 45% of tumour volume replaced by necrosis after GCV (P<0.01 compared to controls). CONCLUSION: In this experimental model of glioblastoma, encapsulation of a xenogeneic packaging cell line increased half-life and transduction efficacy of retrovirus-mediated gene transfer and caused significant tumour necrosis.

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Abstract The aim of this study was to investigate changes in running mechanics and spring-mass behaviour with fatigue induced by 5-hour hilly running (5HHR). Running mechanics were measured pre- and post-5HHR at 10, 12 and 14 km · h(-1) on an instrumented treadmill in eight ultramarathon runners, and sampled at 1000 Hz for 10 consecutive steps. Contact (t(c) ) and aerial (t(a) ) times were determined from ground reaction force (GRF) signals and used to compute step frequency (f). Maximal GRF, loading rate, downward displacement of the centre of mass (Δz), and leg length change (ΔL) during the support phase were determined and used to compute both vertical (K(vert) ) and leg (K(leg) ) stiffness. A significant decrease in t(c) was observed at 12 and 14 km · h(-1) resulting in an increase of f at all speeds. Duty factor and F(max) significantly decreased at 10 km · h(-1). A significant increase in K(vert) and K(leg) was observed at all running speeds with significant decreases in Δz and ΔL. Despite the shorter duration, the changes in running mechanics appeared to be in the same direction (increased f and K(vert) , decrease in Δz and F(max) ) but of lower amplitude compared with those obtained after an ultra-trail or an ultramarathon.

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Arbuscular mycorrhizal fungi (AMF) are obligate symbionts with most terrestrial plants. They improve plant nutrition, particularly phosphate acquisition, and thus are able to improve plant growth. In exchange, the fungi obtain photosynthetically fixed carbon. AMF are coenocytic, meaning that many nuclei coexist in a common cytoplasm. Genetic exchange recently has been demonstrated in the AMF Glomus intraradices, allowing nuclei of different Glomus intraradices strains to mix. Such genetic exchange was shown previously to have negative effects on plant growth and to alter fungal colonization. However, no attempt was made to detect whether genetic exchange in AMF can alter plant gene expression and if this effect was time dependent. Here, we show that genetic exchange in AMF also can be beneficial for rice growth, and that symbiosis-specific gene transcription is altered by genetic exchange. Moreover, our results show that genetic exchange can change the dynamics of the colonization of the fungus in the plant. Our results demonstrate that the simple manipulation of the genetics of AMF can have important consequences for their symbiotic effects on plants such as rice, which is considered the most important crop in the world. Exploiting natural AMF genetic variation by generating novel AMF genotypes through genetic exchange is a potentially useful tool in the development of AMF inocula that are more beneficial for crop growth.

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Mitochondrial dysfunction is one of the possible mechanisms by which azole resistance can occur in Candida glabrata. Cells with mitochondrial DNA deficiency (so-called "petite mutants") upregulate ATP binding cassette (ABC) transporter genes and thus display increased resistance to azoles. Isolation of such C. glabrata mutants from patients receiving antifungal therapy or prophylaxis has been rarely reported. In this study, we characterized two sequential and related C. glabrata isolates recovered from the same patient undergoing azole therapy. The first isolate (BPY40) was azole susceptible (fluconazole MIC, 4 μg/ml), and the second (BPY41) was azole resistant (fluconazole MIC, >256 μg/ml). BPY41 exhibited mitochondrial dysfunction and upregulation of the ABC transporter genes C. glabrata CDR1 (CgCDR1), CgCDR2, and CgSNQ2. We next assessed whether mitochondrial dysfunction conferred a selective advantage during host infection by testing the virulence of BPY40 and BPY41 in mice. Surprisingly, even with in vitro growth deficiency compared to BPY40, BPY41 was more virulent (as judged by mortality and fungal tissue burden) than BPY40 in both systemic and vaginal murine infection models. The increased virulence of the petite mutant correlated with a drastic gain of fitness in mice compared to that of its parental isolate. To understand this unexpected feature, genome-wide changes in gene expression driven by the petite mutation were analyzed by use of microarrays during in vitro growth. Enrichment of specific biological processes (oxido-reductive metabolism and the stress response) was observed in BPY41, all of which was consistent with mitochondrial dysfunction. Finally, some genes involved in cell wall remodelling were upregulated in BPY41 compared to BPY40, which may partially explain the enhanced virulence of BPY41. In conclusion, this study shows for the first time that mitochondrial dysfunction selected in vivo under azole therapy, even if strongly affecting in vitro growth characteristics, can confer a selective advantage under host conditions, allowing the C. glabrata mutant to be more virulent than wild-type isolates.

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The transcription factor serum response factor (SRF) plays a crucial role in the development of several organs. However, its role in the skin has not been explored. Here, we show that keratinocytes in normal human and mouse skin expressed high levels of SRF but that SRF expression was strongly downregulated in the hyperproliferative epidermis of wounded and psoriatic skin. Keratinocyte-specific deletion within the mouse SRF locus during embryonic development caused edema and skin blistering, and all animals died in utero. Postnatal loss of mouse SRF in keratinocytes resulted in the development of psoriasis-like skin lesions. These lesions were characterized by inflammation, hyperproliferation, and abnormal differentiation of keratinocytes as well as by disruption of the actin cytoskeleton. Ultrastructural analysis revealed markedly reduced cell-cell and cell-matrix contacts and loss of cell compaction in all epidermal layers. siRNA-mediated knockdown of SRF in primary human keratinocytes revealed that the cytoskeletal abnormalities and adhesion defects were a direct consequence of the loss of SRF. In contrast, the hyperproliferation observed in vivo was an indirect effect that was most likely a consequence of the inflammation. These results reveal that loss of SRF disrupts epidermal homeostasis and strongly suggest its involvement in the pathogenesis of hyperproliferative skin diseases, including psoriasis.

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Objectifs: To describe the technique and results of radiofrequency ablation (RFA) of small renal tumors.Matériels et méthodes: 28 patients with median age 79 years were treated with RFA for small renal exophytic tumor (median size 20 mm). Most patients were poor operative candidatesbecause of associated morbidity. Four patients were treated for biopsy proven papillary tumor, 7 for clear cell carcinoma, 2 for oncocytoma and one for renalhepatocellular metastasis. No biopsy sample was obtained for the others because of a typical radiological aspect of RCC.Résultats: All patients but one were treated successfully in one session under combined ultrasound and CT guidance using either Radionics 2000 cool-tip or Bostonscientific expandable needles, one was treated in two sessions. One Splenic, 3 colic and 1 pancreatic displacement with CO2 injection and one injection of G5%solution in the costo-phrenic recessus were done in order to protect adjacent organs. Two complications were observed, one splenic iatrogenic lesion treated byembolization and one renal pelvis stenosis treated with JJ stent. After a mean follow-up of 20 months, no patient developped local recurrence on MRI follow-up.Conclusion: RFA is a simple and efficient technique pending on strict selected criteria (small size < 3 cm and exophytic lesion). Long local control is obtained with minimalmorbidity.