47 resultados para Phase-stability
Resumo:
South Peak is a 7-Mm3 potentially unstable rock mass located adjacent to the 1903 Frank Slide on Turtle Mountain, Alberta. This paper presents three-dimensional numerical rock slope stability models and compares them with a previous conceptual slope instability model based on discontinuity surfaces identified using an airborne LiDAR digital elevation model (DEM). Rock mass conditions at South Peak are described using the Geological Strength Index and point load tests, whilst the mean discontinuity set orientations and characteristics are based on approximately 500 field measurements. A kinematic analysis was first conducted to evaluate probable simple discontinuity-controlled failure modes. The potential for wedge failure was further assessed by considering the orientation of wedge intersections over the airborne LiDAR DEM and through a limit equilibrium combination analysis. Block theory was used to evaluate the finiteness and removability of blocks in the rock mass. Finally, the complex interaction between discontinuity sets and the topography within South Peak was investigated through three-dimensional distinct element models using the code 3DEC. The influence of individual discontinuity sets, scale effects, friction angle and the persistence along the discontinuity surfaces on the slope stability conditions were all investigated using this code.
Resumo:
In this paper we unify, simplify, and extend previous work on the evolutionary dynamics of symmetric N-player matrix games with two pure strategies. In such games, gains from switching strategies depend, in general, on how many other individuals in the group play a given strategy. As a consequence, the gain function determining the gradient of selection can be a polynomial of degree N-1. In order to deal with the intricacy of the resulting evolutionary dynamics, we make use of the theory of polynomials in Bernstein form. This theory implies a tight link between the sign pattern of the gains from switching on the one hand and the number and stability of the rest points of the replicator dynamics on the other hand. While this relationship is a general one, it is most informative if gains from switching have at most two sign changes, as is the case for most multi-player matrix games considered in the literature. We demonstrate that previous results for public goods games are easily recovered and extended using this observation. Further examples illustrate how focusing on the sign pattern of the gains from switching obviates the need for a more involved analysis.
Resumo:
Background: Previous studies reported an increase of mean platelet volume (MPV) in patients with acute ischemic stroke. However, its correlation with stroke severity has not been investigated. Moreover, studies on the association of MPV with functional outcome yielded inconsistent results. Methods: We included all consecutive ischemic stroke patients admitted to CHUV (Centre Hospitalier Universitaire Vaudois) Neurology Service within 24 h after stroke onset who had MPV measured on admission. The association of MPV with stroke severity (NIHSS score at admission and at 24 h) and outcome (Rankin Scale score at 3 and 12 months) was analyzed in univariate analysis. The chi(2) test was performed to compare the frequency of minor strokes (NIHSS score </=4) and good functional outcome (Rankin Scale score </=2) across MPV quartiles. The ANOVA test was used to compare MPV between stroke subtypes according to the TOAST classification. Student's two-tailed unpaired t test was performed to compare MPV between lacunar and nonlacunar strokes. MPV was generated at admission by the Sysmex XE-2100 automated cell counter (Sysmex Corporation, Kobe, Japan) from EDTA blood samples. Results: There was no significant difference in the frequency of minor strokes (p = 0.46) and good functional outcome (p = 0.06) across MPV quartiles. MPV was not associated with stroke severity or outcome in univariate analysis. There was no significant difference in MPV between stroke subtypes according to the TOAST classification (p = 0.173) or between lacunar and nonlacunar strokes (10.50 +/- 0.91 vs. 10.40 +/- 0.81 fl, p = 0.322). Conclusions: MPV, assessed within 24 h after ischemic stroke onset, is not associated with stroke severity or functional outcome.
Resumo:
The benefit of bevacizumab (Bv) has been shown in different tumors including colorectal cancer, renal cancer, pulmonary non-small cell cancer and also breast cancer. However to date, there is no established test evaluating the angiogenic status of a patient and monitoring the effects of anti-angiogenic treatments. Tumor angiogenesis is the result of a balance between multiple pro- and anti¬angiogenic molecules. There is very little published clinical data exploring the impact of the anti-angiogenic therapy on the different angiogenesis-related molecules and the potential role of these molecules as prognostic or predictive factors.
Resumo:
BACKGROUND: Cilengitide is a selective integrin inhibitor that is well tolerated and has demonstrated biologic activity in patients with recurrent malignant glioma. The primary objectives of this randomized phase 2 trial were to determine the safety and efficacy of cilengitide when combined with radiation and temozolomide for patients with newly diagnosed glioblastoma multiforme and to select a dose for comparative clinical testing. METHODS: In total, 112 patients were accrued. Eighteen patients received standard radiation and temozolomide with cilengitide in a safety run-in phase followed by a randomized phase 2 trial with 94 patients assigned to either a 500 mg dose group or 2000 mg dose group. The trial was designed to estimate overall survival benefit compared with a New Approaches to Brain Tumor Therapy (NABTT) Consortium internal historic control and data from the published European Organization for Research and Treatment of Cancer (EORTC) trial EORTC 26981. RESULTS: Cilengitide at all doses studied was well tolerated with radiation and temozolomide. The median survival was 19.7 months for all patients, 17.4 months for the patients in the 500 mg dose group, 20.8 months for patients in the 2000 mg dose group, 30 months for patients who had methylated O6-methylguanine-DNA methyltransferase (MGMT) status, and 17.4 months for patients who had unmethylated MGMT status. For patients aged ≤70 years, the median survival and survival at 24 months was superior to what was observed in the EORTC trial (20.7 months vs 14.6 months and 41% vs 27%, respectively; P = .008). CONCLUSIONS: Cilengitide was well tolerated when combined with standard chemoradiation and may improve survival for patients newly diagnosed with glioblastoma multiforme regardless of MGMT methylation status. The authors concluded that, from an efficacy and safety standpoint, future trials of this agent in this population should use the 2000 mg dose. Cancer 2012. © 2012 American Cancer Society.
Resumo:
BACKGROUND: Sunitinib (SU) is a multitargeted tyrosine kinase inhibitor with antitumor and antiangiogenic activity. The objective of this trial was to demonstrate antitumor activity of continuous SU treatment in patients with hepatocellular carcinoma (HCC). PATIENTS AND METHODS: Key eligibility criteria included unresectable or metastatic HCC, no prior systemic anticancer treatment, measurable disease, and Child-Pugh class A or mild Child-Pugh class B liver dysfunction. Patients received 37.5 mg SU daily until progression or unacceptable toxicity. The primary endpoint was progression-free survival at 12 weeks (PFS12). RESULTS: Forty-five patients were enrolled. The median age was 63 years; 89% had Child-Pugh class A disease and 47% had distant metastases. PFS12 was rated successful in 15 patients (33%; 95% confidence interval, 20%-47%). Over the whole trial period, one complete response and a 40% rate of stable disease as the best response were achieved. The median PFS duration, disease stabilization duration, time to progression, and overall survival time were 1.5, 2.9, 1.5, and 9.3 months, respectively. Grade 3 and 4 adverse events were infrequent. None of the 33 deaths were considered drug related. CONCLUSION: Continuous SU treatment with 37.5 mg daily is feasible and has moderate activity in patients with advanced HCC and mild to moderately impaired liver dysfunction. Under this trial design (>13 PFS12 successes), the therapy is considered promising. This is the first trial describing the clinical effects of continuous dosing of SU in HCC patients on a schedule that is used in an ongoing, randomized, phase III trial in comparison with the current treatment standard, sorafenib (ClinicalTrials.gov identifier, NCT00699374).
Resumo:
On December 4th 2007, a 3-Mm3 landslide occurred along the northwestern shore of Chehalis Lake. The initiation zone is located at the intersection of the main valley slope and the northern sidewall of a prominent gully. The slope failure caused a displacement wave that ran up to 38 m on the opposite shore of the lake. The landslide is temporally associated with a rain-on-snow meteorological event which is thought to have triggered it. This paper describes the Chehalis Lake landslide and presents a comparison of discontinuity orientation datasets obtained using three techniques: field measurements, terrestrial photogrammetric 3D models and an airborne LiDAR digital elevation model to describe the orientation and characteristics of the five discontinuity sets present. The discontinuity orientation data are used to perform kinematic, surface wedge limit equilibrium and three-dimensional distinct element analyses. The kinematic and surface wedge analyses suggest that the location of the slope failure (intersection of the valley slope and a gully wall) has facilitated the development of the unstable rock mass which initiated as a planar sliding failure. Results from the three-dimensional distinct element analyses suggest that the presence, orientation and high persistence of a discontinuity set dipping obliquely to the slope were critical to the development of the landslide and led to a failure mechanism dominated by planar sliding. The three-dimensional distinct element modelling also suggests that the presence of a steeply dipping discontinuity set striking perpendicular to the slope and associated with a fault exerted a significant control on the volume and extent of the failed rock mass but not on the overall stability of the slope.
Resumo:
Despite the long tradition for asking about the negative social and health consequences of alcohol consumption in surveys, little is known about the dimensionality of these consequences. Analysing cross-sectional and longitudinal data from the Nordic Taxation Study collected for Sweden, Finland, and Denmark in two waves in 2003 and 2004 by means of an explorative principal component analysis for categorical data (CATPCA), it is tested whether consequences have a single underlying dimension across cultures. It further tests the reliability, replicability, concurrent and predictive validity of the consequence scales. A one-dimensional solution was commonly preferable. Whereas the two-dimensional solution was unable to distinguish clearly between different concepts of consequences, the one-dimensional solution resulted in interpretable, generally very stable scales within countries across different samples and time.
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Analysis of Schizosaccharomyces pombe mutants that are defective in septum formation and cytokinesis has identified the product of the cdc15 gene as a key element in formation of a division septum. S. pombe cells lacking cdc15p function cannot assemble a functional medial ring, and do not make a division septum. cdc15 mRNA accumulates periodically during the cell cycle, peaking after entry into mitosis, and increased expression of the gene in G2-arrested cells can promote F-actin ring formation. Here, we have investigated the effects of mutations that block cell division upon the expression of cdc15 in synchronised cell populations, and analysed the expression of cdc15 when septum formation is induced by ectopic activation of the septation signalling network. We concluded the following: (i) the septation signalling network genes are not required for periodic accumulation of cdc15 mRNA; (ii) induction of septum formation in G2-arrested cells by activation of the septation signalling network does not result in accumulation of cdc15 mRNA, which is therefore not a prerequisite for septum formation; (iii) failure to turn off septum formation at the end of mitosis results in continued expression of cdc15; and (iv) periodic accumulation of cdc15 mRNA is mediated by a 97 bp region 5' to the mRNA start site.
Resumo:
This article analyses stability and volatility of party preferences using data from the Swiss Household-Panel (SHP), which, for the first time, allow studying transitions and stability of voters over several years in Switzerland. Analyses cover the years 1999- 2007 and systematically distinguish changes between party blocks and changes within party blocks. The first part looks at different patterns of change, which show relatively high volatility. The second part tests several theories on causes of such changes applying a multinomial random-effects model. Results show that party preferences stabilise with their duration and with age and that the electoral cycle, political sophistication, socio-structural predispositions, the household-context as well as party size and the number of parties each explain part of electoral volatility. Different results for withinand between party-block changes underlie the importance of that differentiation.
Resumo:
PURPOSE: NovoTTF-100A is a portable device delivering low-intensity, intermediate frequency electric fields via non-invasive, transducer arrays. Tumour Treatment Fields (TTF), a completely new therapeutic modality in cancer treatment, physically interfere with cell division. METHODS: Phase III trial of chemotherapy-free treatment of NovoTTF (20-24h/day) versus active chemotherapy in the treatment of patients with recurrent glioblastoma. Primary end-point was improvement of overall survival. RESULTS: Patients (median age 54years (range 23-80), Karnofsky performance status 80% (range 50-100) were randomised to TTF alone (n=120) or active chemotherapy control (n=117). Number of prior treatments was two (range 1-6). Median survival was 6.6 versus 6.0months (hazard ratio 0.86 [95% CI 0.66-1.12]; p=0.27), 1-year survival rate was 20% and 20%, progression-free survival rate at 6months was 21.4% and 15.1% (p=0.13), respectively in TTF and active control patients. Responses were more common in the TTF arm (14% versus 9.6%, p=0.19). The TTF-related adverse events were mild (14%) to moderate (2%) skin rash beneath the transducer arrays. Severe adverse events occurred in 6% and 16% (p=0.022) of patients treated with TTF and chemotherapy, respectively. Quality of life analyses favoured TTF therapy in most domains. CONCLUSIONS: This is the first controlled trial evaluating an entirely novel cancer treatment modality delivering electric fields rather than chemotherapy. No improvement in overall survival was demonstrated, however efficacy and activity with this chemotherapy-free treatment device appears comparable to chemotherapy regimens that are commonly used for recurrent glioblastoma. Toxicity and quality of life clearly favoured TTF.
Resumo:
The evolution of a quantitative phenotype is often envisioned as a trait substitution sequence where mutant alleles repeatedly replace resident ones. In infinite populations, the invasion fitness of a mutant in this two-allele representation of the evolutionary process is used to characterize features about long-term phenotypic evolution, such as singular points, convergence stability (established from first-order effects of selection), branching points, and evolutionary stability (established from second-order effects of selection). Here, we try to characterize long-term phenotypic evolution in finite populations from this two-allele representation of the evolutionary process. We construct a stochastic model describing evolutionary dynamics at non-rare mutant allele frequency. We then derive stability conditions based on stationary average mutant frequencies in the presence of vanishing mutation rates. We find that the second-order stability condition obtained from second-order effects of selection is identical to convergence stability. Thus, in two-allele systems in finite populations, convergence stability is enough to characterize long-term evolution under the trait substitution sequence assumption. We perform individual-based simulations to confirm our analytic results.