89 resultados para Statistical hypothesis testing


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Obesity is associated with skeletal muscle insulin resistance, which is a crucial step in the development of type 2 diabetes. Among the mechanisms by which obesity may lead to insulin resistance, lipotoxicity is one of the hypotheses being explored; others include inflammation or the oxidative stress hypotheses. This review focuses on the role of diacylglycerols (DAG), a family of lipid metabolites implicated in the pathogenesis of lipotoxicity and insulin resistance. While recent studies report contradictory results in humans with regard to the importance of DAG-induced insulin resistance in skeletal muscle, other current literature highlight a potential role for DAG as signalling molecules. This review will discuss possible hypotheses explaining these contradictory results and the need to explore further the role of DAG in human metabolism.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Treponema pallidum PCR (Tp-PCR) has been noted as a valid method for diagnosing syphilis. We compared Tp-PCR to a combination of darkfield microscopy (DFM), the reference method, and serologic testing in a cohort of 273 patients from France and Switzerland and found the diagnostic accuracy of Tp-PCR was higher than that for DFM.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Limited information is available regarding the methodology required to characterize hashish seizures for assessing the presence or the absence of a chemical link between two seizures. This casework report presents the methodology applied for assessing that two different police seizures were coming from the same block before this latter one was split. The chemical signature was extracted using GC-MS analysis and the implemented methodology consists in a study of intra- and inter-variability distributions based on the measurement of the chemical profiles similarity using a number of hashish seizures and the calculation of the Pearson correlation coefficient. Different statistical scenarios (i.e., a combination of data pretreatment techniques and selection of target compounds) were tested to find the most discriminating one. Seven compounds showing high discrimination capabilities were selected on which a specific statistical data pretreatment was applied. Based on the results, the statistical model built for comparing the hashish seizures leads to low error rates. Therefore, the implemented methodology is suitable for the chemical profiling of hashish seizures.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Forensic scientists have long detected the presence of drugs and their metabolites in biological materials using body fluids such as urine, blood and/or other biological liquids or tissues. For doping analysis, only urine has so far been collected. In recent years, remarkable advances in sensitive analytical techniques have encouraged the analysis of drugs in unconventional biological samples such as hair, saliva and sweat. These samples are easily collected, although drug levels are often lower than the corresponding levels in urine or blood. This chapter reviews recent studies in the detection of doping agents in hair, saliva and sweat. Sampling, analytical procedures and interpretation of the results are discussed in comparison with those obtained from urine and blood samples.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

For several decades mechanical properties of shallow formations (soil) obtained by sonic to ultrasonic wave testing were reported to be greater than those based on mechanical tests. The present article relying on a statistical analysis of more than 300 tests shows that elastic moduli of the soil can indeed be obtained from (ultra)sonic tests and that they are identical to those resulting from mechanical tests.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Objective: Standard treatment of locally advanced (stages III and IV A-B) nasopharyngeal carcinoma (NPC) consists in chemoradiotherapy with 5-y survival rates of around 60%. However, acute toxicity prevents the administration of adequate adjuvant chemotherapy in nearly half of the patients. This situation has led to the hypothesis that induction chemotherapy followed by chemoradiotherapy may be a superior approach. Many ongoing studies are testing the role of induction chemotherapy in this setting. Newer radiotherapy techniques are becoming available (intensity modulated radiotherapy [IMRT] and tomotherapy). They can achieve a higher degree of accuracy in conforming the radiation to the planned target volume while sparing normal tissue resulting in less acute and long-term toxicity. Methods: We report here our local experience of 11 consecutive locally advanced NPC patients treated between June 2004 and October 2007. Median age was 46 years (range, 17-65). All but one were male patients. Initial stage was stage III in 5, and stage IVA-B in 6 patients. Treatment consisted of 3 cycles of induction TCF (Docetaxel 75 mg/m2- Cisplatin 75 mg/m2- 5-fluorouracil 750 mg/m2/d 5 days) chemotherapy followed by concomitant chemoradiotherapy with 3 cycles of cisplatin (100 mg/m2), or carboplatin (AUC 5) in case of renal impairment. Radiotherapy was delivered by either IMRT or tomotherapy. Macroscopic disease (tumor + involved lymph nodes) was treated with 70 Gy, 2 Gy/fraction (IMRT), or 69.6 Gy, 1.12 Gy/fraction (simultaneus integrated boost [SIB] technique). Elective nodal irradiation of 46-54 Gy lymph was performed in all patients, whereas elective irradiation of the entire nasopharynx (60 Gy) half of patients. Results: All but one tumor were EBV positive. Induction chemotherapy was done as planned for 8 patients (73%). Two patients had only 2 cycles, 1 patient had only1 cycle of TCF, and the other without docetaxel. Concomitant chemotherapy was given as planned in 7 patients (64%). Four patients had only 2 cycles. Radiotherapy could be delivered as planned in all patients. Eight weeks post treatment all patients proved to have a CR (CR or uCR). After a median follow-up of 11 months (range, 6-38 months) only one patient has relapsed. Details on acute and 1 year toxicities will be presented. Conclusion: Treatment of locally advancedNPC with induction and concomitant chemotherapy is feasible and well tolerated. The use of IMRT or tomotherapy technique seems to ameliorate the therapeutic index particularly in regard with xerostomia. All our patients presented a complete response. For the assessment of survival and long-term toxicity, a longer follow-up period is needed.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Twelve primers to amplify microsatellite markers from the chloroplast genome of Lolium perenne were designed and optimized using de novo sequencing and in silico sequences. With one exception, each locus was polymorphic with a range from two to nine alleles in L. perenne. The newly developed primer pairs cross-amplified in different species of Lolium and in 50 other grass species representing nine grass subfamilies.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

There has been a long debate since the introduction of blood analysis prior to major sports events, to find out whether blood samples should be analysed right away on the site of competition or whether they should be transported and analysed in an anti-doping laboratory. Therefore, it was necessary to measure blood samples and compare the results obtained right after the blood withdrawal with those obtained after a few hours delay. Furthermore, it was interesting to determine the effect of temperature on the possible deterioration of red blood cell analytes used for testing recombinant erythropoietin abuse. Healthy volunteers were asked to give two blood samples and one of these was kept at room temperature whereas the second one was put into a refrigerator. On a regular basis, the samples were rolled for homogenisation and temperature stabilisation and were analysed with the same haematological apparatus. The results confirmed that blood controls prior to competition should be performed as soon as possible with standardised pre-analytical conditions to avoid too many variations notably on the haematocrit and the reticulocyte count. These recommendations should ideally also be applied to the all the blood controls compulsory for the medical follow up, otherwise unexplainable values could be misinterpreted and could for instance lead to a period of incapacity.

Relevância:

20.00% 20.00%

Publicador:

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Per definition, alcohol expectancies (after alcohol I expect X), and drinking motives (I drink to achieve X) are conceptually distinct constructs. Theorists have argued that motives mediate the association between expectancies and drinking outcomes. Yet, given the use of different instruments, do these constructs remain distinct when assessment items are matched? The present study tested to what extent motives mediated the link between expectancies and alcohol outcomes when identical items were used, first as expectancies and then as motives. A linear structural equation model was estimated based on a national representative sample of 5,779 alcohol-using students in Switzerland (mean age = 15.2 years). The results showed that expectancies explained up to 38% of the variance in motives. Together with motives, they explained up to 48% of the variance in alcohol outcomes (volume, 5+ drinking, and problems). In 10 of 12 outcomes, there was a significant mediated effect that was often higher than the direct expectancy effect. For coping, the expectancy effect was close to zero, indicating the strongest form of mediation. In only one case (conformity and 5+ drinking), there was a direct expectancy effect but no mediation. To conclude, the study demonstrates that motives are distinct from expectancies even when identical items are used. Motives are more proximally related to different alcohol outcomes, often mediating the effects of expectancies. Consequently, the effectiveness of interventions, particularly those aimed at coping drinkers, should be improved through a shift in focus from expectancies to drinking motives.