9,182 research outputs found
Assessment of SVM Reliability for Microarray Data Analysis
The goal of our research is to provide techniques that can assess and validate the results of SVM-based analysis of microarray data. We present preliminary results of the effect of mislabeled training samples. We conducted several systematic experiments on artificial and real medical data using SVMs. We systematically flipped the labels of a fraction of the training data. We show that a relatively small number of mislabeled examples can dramatically decrease the performance as visualized on the ROC graphs. This phenomenon persists even if the dimensionality of the input space is drastically decreased, by using for example feature selection. Moreover we show that for SVM recursive feature elimination, even a small fraction of mislabeled samples can completely change the resulting set of genes. This work is an extended version of the previous paper [MBN04]
A Hike in the Phases of the 1-in-3 Satisfiability
We summarise our results for the random --1-in-3 satisfiability
problem, where is a probability of negation of the variable. We
employ both rigorous and heuristic methods to describe the SAT/UNSAT and
Hard/Easy transitions.Comment: 2 pages, introductory level, proceed. for the Les Houches Session
LXXXV 2006 on Complex System
Evaluating the Interest-Rate Risk of Adjustable-Rate Mortgage Loans
This paper evaluates the interest-rate risk inherent in an adjustable-rate mortgage (ARM) with sporadic rate adjustments and possibly binding periodic and life-of-loan rate change constraints. Simulation analysis forecasts ARM cash flows, determines the probability that constraints will hold, and partitions the loan into fixed and variable components. Simulation parameters are then altered to measure the impact of changes in contract terms and market conditions on the interest-rate risk of a typical ARM loan. Interest-rate sensitivity is found to be significantly less than that of fixed-rate loans and remarkably insensitive to changes in loan margins or initial loan rates after the first few years of an ARM's life. Therefore, it is not surprising that lenders have used these features to lure borrowers to ARMs. Periodic rate change limits and volatility in the underlying index are the only factors that influence the interest-rate risk of an existing ARM in a substantive way.
Role of Air in Granular Jet Formation
A steel ball impacting on a bed of very loose, fine sand results in a surprisingly vigorous jet which shoots up from the surface of the sand [D. Lohse et al., Phys. Rev. Lett. 93, 198003 (2004)]. When the ambient pressure p is reduced, the jet is found to be less vigorous [R. Royer et al., Nature Phys. 1, 164 (2005)]. In this Letter we show that p also affects the rate of penetration of the ball: Higher pressure increases the rate of penetration, which makes the cavity created by the ball close deeper into the sand bed, where the hydrostatic pressure is stronger, thereby producing a more energetic collapse and jetting. The origin of the deeper penetration under normal ambient pressure is found to lie in the extra sand fluidization caused by the air flow induced by the falling ball
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Euro-Americans vs. Latinos in U.S. Politics
The following issue brief will focus on the differences in voting patterns among Latinos and European-Americans -- whites, as they are indicated on the 2000 U.S. census form -- and the issues that are hallmark of the Latino population as opposed to the European-American population. In addition, the demographics of both ethno-racial populations will be discussed
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Peroxisome proliferator-activated receptor (PPAR)alpha expression in T cells mediates gender differences in development of T cell-mediated autoimmunity.
Peroxisome proliferator-activated receptor (PPAR)alpha is a nuclear receptor that mediates gender differences in lipid metabolism. PPARalpha also functions to control inflammatory responses by repressing the activity of nuclear factor kappaB (NF-kappaB) and c-jun in immune cells. Because PPARalpha is situated at the crossroads of gender and immune regulation, we hypothesized that this gene may mediate sex differences in the development of T cell-mediated autoimmune disease. We show that PPARalpha is more abundant in male as compared with female CD4(+) cells and that its expression is sensitive to androgen levels. Genetic ablation of this gene selectively removed the brake on NF-kappaB and c-jun activity in male T lymphocytes, resulting in higher production of interferon gamma and tumor necrosis factor (but not interleukin 17), and lower production of T helper (Th)2 cytokines. Upon induction of experimental autoimmune encephalomyelitis, male but not female PPARalpha(-/-) mice developed more severe clinical signs that were restricted to the acute phase of disease. These results suggest that males are less prone to develop Th1-mediated autoimmunity because they have higher T cell expression of PPARalpha
Motor and non-motor improvements following short-term multidisciplinary day-clinic care in Parkinson's disease
Background: Inpatient as well as outpatient care does often not meet PD-patients' individual needs.
Introduction: Day-clinic concepts encompassing a multidisciplinary team as well as therapy adjustments accompanying everyday demands aim at filling this gap.
Methods: This is a retrospective study on short-term effects of a 3 week multidisciplinary rehabilitation program in patients with Parkinson's disease (PD) embedded in a specialized movement disorder day-clinic. We analyzed short-term outcome of motor and non-motor symptoms (NMS) in 143 PD-patients (mean age 65.3 +/- 11.9 years; Hoehn-and-Yahr-score 2.6 +/- 0.7) after 3 weeks with 7.4 +/- 1.8 active days of interdisciplinary day-care treatment. Participants attended the day-clinic in groups of five patients at a time. Improvements were evaluated by comparison of standardized physical therapy assessments, disease specific scores for motor symptoms (MDS-UPDRS III), mood (BDI), quality of life (PDQ39, SF36), sleep (PDSS, ESS), impulsiveness (QUIP), apathy (SAS), cognition (MMST), as well as change in medication before and directly after the intervention.
Results: MDS-UPDRS motor score improved significantly by 22.9 +/- 21.5% (p < 0.001) and was accompanied by a significant reduction of imbalance, immobility, and weakness ranging between 6% and 17% in standardized physical therapy tests. In addition, all disease-specific non-motor scales improved significantly.
Conclusions: A multidisciplinary day-clinic approach can support benefit on motor, non-motor symptoms and QoL in PD-patients. Given the increase in PD incidence and prevalence as well as the significant treatment effects shown here, more day-clinic treatment opportunities ought to be implemented to improve PD treatment adapted to everyday challenges while still reducing costs to the health care system
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