A Bounded-Size Likelihood Test for Non- Nested Probabilistic Discrete Choice Models Estimated from Choice-Based Samples

Discrete-choice models of the hierarchical logit form enable the analyst to configure tree structures and to investigate the relative statistical and behavioural strengths of alternative hierarchies. The alternative tree structures can be nested or nonnested in a specification sense, and the underlying sample of observations can be exogenous or endogenous. When the sample is endogenous (i.e. choice based) and alternative tree structures are non-nested in a statistically comparative sense, the conventional likelihood ratio tests for comparisons of exogenously sampled nested hierarchical models are not appropriate. This paper presents a bounded-size likelihood ratio test for non-nested discrete choice models estimated from choice-based samples. The tests are presented with and without correction for sample size. We apply the test using a sample of four transport modes for long distance non-business travel in Australia

Statistical Entropy of Nonextremal Four-Dimensional Black Holes and U-Duality

We identify the states in string theory which are responsible for the entropy of near-extremal rotating four-dimensional black holes in $N=8$ supergravity. For black holes far from extremality (with no rotation), the Bekenstein-Hawking entropy is exactly matched by a mysterious duality invariant extension of the formulas derived for near-extremal black holes states.Comment: 9 pages, harvma

Timing Robustness in the Budding and Fission Yeast Cell Cycles

Robustness of biological models has emerged as an important principle in systems biology. Many past analyses of Boolean models update all pending changes in signals simultaneously (i.e., synchronously), making it impossible to consider robustness to variations in timing that result from noise and different environmental conditions. We checked previously published mathematical models of the cell cycles of budding and fission yeast for robustness to timing variations by constructing Boolean models and analyzing them using model-checking software for the property of speed independence. Surprisingly, the models are nearly, but not totally, speed-independent. In some cases, examination of timing problems discovered in the analysis exposes apparent inaccuracies in the model. Biologically justified revisions to the model eliminate the timing problems. Furthermore, in silico random mutations in the regulatory interactions of a speed-independent Boolean model are shown to be unlikely to preserve speed independence, even in models that are otherwise functional, providing evidence for selection pressure to maintain timing robustness. Multiple cell cycle models exhibit strong robustness to timing variation, apparently due to evolutionary pressure. Thus, timing robustness can be a basis for generating testable hypotheses and can focus attention on aspects of a model that may need refinement

Plane waves with weak singularities

We study a class of time dependent solutions of the vacuum Einstein equations which are plane waves with weak null singularities. This singularity is weak in the sense that though the tidal forces diverge at the singularity, the rate of divergence is such that the distortion suffered by a freely falling observer remains finite. Among such weak singular plane waves there is a sub-class which do not exhibit large back reaction in the presence of test scalar probes. String propagation in these backgrounds is smooth and there is a natural way to continue the metric beyond the singularity. This continued metric admits string propagation without the string becoming infinitely excited. We construct a one parameter family of smooth metrics which are at a finite distance in the space of metrics from the extended metric and a well defined operator in the string sigma model which resolves the singularity.Comment: 22 pages, Added references and clarifying comment

Statistical Origin of Black Hole Entropy in Matrix Theory

The statistical entropy of black holes in M-theory is considered. Assuming Matrix theory is the discretized light-cone quantization of a theory with eleven-dimensional Lorentz invariance, we map the counting problem onto the original Gibbons-Hawking calculation of the thermodynamic entropy.Comment: 9 pages, harvmac, (v2 References added, typo fixed), (v3 Some clarifying comments added.

Black Hole Hair Removal: Non-linear Analysis

BMPV black holes in flat transverse space and in Taub-NUT space have identical near horizon geometries but different microscopic degeneracies. It has been proposed that this difference can be accounted for by different contribution to the degeneracies of these black holes from hair modes, -- degrees of freedom living outside the horizon. In this paper we explicitly construct the hair modes of these two black holes as finite bosonic and fermionic deformations of the black hole solution satisfying the full non-linear equations of motion of supergravity and preserving the supersymmetry of the original solutions. Special care is taken to ensure that these solutions do not have any curvature singularity at the future horizon when viewed as the full ten dimensional geometry. We show that after removing the contribution due to the hair degrees of freedom from the microscopic partition function, the partition functions of the two black holes agree.Comment: 40 pages, LaTe

The duodenal mucosa in patients with renal failure: Response to 1,25(OH)2D3

The duodenal mucosa in patients with renal failure: Response to 1,25(OH)2D3. The structure of the duodenal mucosa was evaluated i n duodenal biopsy samples obtained from patients with moderate renal failure (MRF) and in dialysis patients (HD) in an effort to examine the possibility that changes in duodenal mucosa may contribute to the impaired calcium absorption in renal failure (RF). The effect of therapy with 1,25(OH)2D3 on the duodenal mucosa in the HD patients was also studied. The results show that both MRF and HD patients have reduction in calcium reabsorption and in the length of their intestinal villi and crypts of Lieberkuhn. In the HD patients, these structural changes were more severe. Treatment with 1,25(OH)2D3 produced significant improvement in calcium reabsorption (P < 0.01) as well as in length of villus and crypt (P < 0.02) and increased mitotic activity in the crypts (P < 0.02). Electron microscopy revealed the microvilli to be shorter, irregularly distributed, moth-eaten, and grainy, with these abnormalities disappearing after treatment. The data show that duodenal mucosa in RF exhibits structural abnormalities, which were normalized after 1,25(OH)2D3 therapy, and suggest that these derangements may play a role in the defective calcium reabsorption in RF.La muqueuse duodénale chez les malades en insuffisance rénale: Réponse au 1,25(OH)2D3. La structure de la muqueuse duodénale a été évaluée sur des biopsies duodénales de malades atteints d'insuffisance rénale modérée (MFR) et de malades en hémodialyse (HD) afin d'étudier l'hypothèse selon laquelle des modifications de la muqueuse duodénale pourraient contribuer à l'altération de l'absorption du calcium au cours de l'insuffisance rénale. L'effet du traitement par 1,25(OH)2D3 sur la muqueuse duodénale a été étudié chez les malades HD. Les résultats montrent que les malades MRF et HD ont une diminution de l'absorption du calcium et de la longueur de leurs villosités intestinales et de leurs cryptes de Lieberkuhn. Chez les malades HD ces modifications de structure sont encore plus sévères. Le traitement par 1,25(OH)2D3 détermine une amélioration significative de l'absorption du calcium (P < 0,01) de même qu'une augmentation de la longueur des villosités et des cryptes (P < 0,02) et une augmentation de l'activité mitotique dans les cryptes (P < 0,02). La microscopie électronique montre que les micro-villosités sont raccourcies, irrégulièrement distribuées et d'aspect mité et granuleux, anomalies qui disparaissent après le traitement. Les résultats montrent que la muqueuse duodénale des malades RF a des anomalies de structure qui sont normalisées au cours du traitement par 1,25(OH)2D3 et suggèrent que ces modifications peuvent jouer un rôle dans le déficit de au cours de RF

M.C.R.G. Study of Fixed-connectivity Surfaces

We apply Monte Carlo Renormalization group to the crumpling transition in random surface models of fixed connectivity. This transition is notoriously difficult to treat numerically. We employ here a Fourier accelerated Langevin algorithm in conjunction with a novel blocking procedure in momentum space which has proven extremely successful in $\lambda\phi^4$. We perform two successive renormalizations in lattices with up to $64^2$ sites. We obtain a result for the critical exponent $\nu$ in general agreement with previous estimates and similar error bars, but with much less computational effort. We also measure with great accuracy $\eta$. As a by-product we are able to determine the fractal dimension $d_H$ of random surfaces at the crumpling transition.Comment: 35 pages,Latex file, 6 Postscript figures uuencoded,uses psfig.sty 2 misspelled references corrected and one added. Paper unchange

NRG Oncology/RTOG 0921: A phase 2 study of postoperative intensity-modulated radiotherapy with concurrent cisplatin and bevacizumab followed by carboplatin and paclitaxel for patients with endometrial cancer.

BACKGROUND: The current study was conducted to assess acute and late adverse events (AEs), overall survival (OS), pelvic failure, regional failure, distant failure, and disease-free survival in a prospective phase 2 clinical trial of bevacizumab and pelvic intensity-modulated radiotherapy (IMRT) with chemotherapy in patients with high-risk endometrial cancer. METHODS: Patients underwent a hysterectomy and lymph node removal, and had ≥1 of the following high-risk factors: grade 3 carcinoma with \u3e50% myometrial invasion, grade 2 or 3 disease with any cervical stromal invasion, or known extrauterine extension confined to the pelvis. Treatment included pelvic IMRT and concurrent cisplatin on days 1 and 29 of radiation and bevacizumab (at a dose of 5 mg/kg on days 1, 15, and 29 of radiation) followed by adjuvant carboplatin and paclitaxel for 4 cycles. The primary endpoint was grade ≥3 AEs occurring within the first 90 days (toxicity was graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events [version 4.0]). RESULTS: A total of 34 patients were accrued from November 2009 through December 2011, 30 of whom were eligible and received study treatment. Seven of 30 patients (23.3%; 1-sided 95% confidence interval, 10.6%-36.0%) developed grade ≥3 treatment-related nonhematologic toxicities within 90 days; an additional 6 patients experienced grade ≥3 toxicities between 90 and 365 days after treatment. The 2-year OS rate was 96.7% and the disease-free survival rate was 79.1%. No patient developed a within-field pelvic failure and no patients with International Federation of Gynecology and Obstetrics stage I to IIIA disease developed disease recurrence after a median follow-up of 26 months. CONCLUSIONS: Postoperative bevacizumab added to chemotherapy and pelvic IMRT appears to be well tolerated and results in high OS rates at 2 years for patients with high-risk endometrial carcinoma

Stacking non-BPS D-Branes

We present a candidate supergravity solution for a stacked configuration of stable non-BPS D-branes in Type II string theory compactified on T^4/Z_2. This gives a supergravity description of nonabelian tachyon condensation on the brane worldvolume.Comment: 10 pages, revte