Compressible flow structures interaction with a two-dimensional ejector: a cold-flow study

An experimental study has been conducted to examine the interaction of compressible flow structures such as shocks and vortices with a two-dimensional ejector geometry using a shock-tube facility. Three diaphragm pressure ratios ofP4 =P1 = 4, 8, and 12 have been employed, whereP4 is the driver gas pressure andP1 is the pressure within the driven compartment of the shock tube. These lead to incident shock Mach numbers of Ms = 1:34, 1.54, and 1.66, respectively. The length of the driver section of the shock tube was 700 mm. Air was used for both the driver and driven gases. High-speed shadowgraphy was employed to visualize the induced flowfield. Pressure measurements were taken at different locations along the test section to study theflow quantitatively. The induced flow is unsteady and dependent on the degree of compressibility of the initial shock wave generated by the rupture of the diaphragm

Recursive Sparse Point Process Regression with Application to Spectrotemporal Receptive Field Plasticity Analysis

We consider the problem of estimating the sparse time-varying parameter vectors of a point process model in an online fashion, where the observations and inputs respectively consist of binary and continuous time series. We construct a novel objective function by incorporating a forgetting factor mechanism into the point process log-likelihood to enforce adaptivity and employ $\ell_1$-regularization to capture the sparsity. We provide a rigorous analysis of the maximizers of the objective function, which extends the guarantees of compressed sensing to our setting. We construct two recursive filters for online estimation of the parameter vectors based on proximal optimization techniques, as well as a novel filter for recursive computation of statistical confidence regions. Simulation studies reveal that our algorithms outperform several existing point process filters in terms of trackability, goodness-of-fit and mean square error. We finally apply our filtering algorithms to experimentally recorded spiking data from the ferret primary auditory cortex during attentive behavior in a click rate discrimination task. Our analysis provides new insights into the time-course of the spectrotemporal receptive field plasticity of the auditory neurons

Predictors of curve flexibility in adolescent idiopathic scoliosis: A retrospective study of 100 patients

Curve flexibility in adolescent idiopathic scoliosis (AIS) was one of the major concerns of spinal surgeons since the evolution of surgical correction techniques. In this respect, many tried to identify which criteria denote more rigid curve. In the present study, we aimed toward determining important factors influencing AIS curve flexibility on supine bending films. We assessed radiographs of 100 patients with AIS for direction of curves, number of involved vertebrae, apical vertebral translation and rotation, magnitude of main thoracic curve and T5-T12 kyphosis. Statistical analysis performed via stepwise linear regression model with these variables plus age and sex against flexibility index. According to regression analysis, there was a clear relationship between flexibility indexes (FI) and magnitude of main thoracic curve at all (P50) against rigid curves, apical vertebral rotation was a major determinant of curve flexibility also (P<0.001). Adolescent idiopathic scoliosis curves with larger Cobb�s angle and apical vertebral rotation show less flexibility on supine bending films. © 2015 Tehran University of Medical Sciences. All rights reserved

Quantum Hall Effect on the Grassmannians Gr2(CN)\mathbf{Gr}_2(\mathbb{C}^N)

Quantum Hall Effects (QHEs) on the complex Grassmann manifolds $\mathbf{Gr}_2(\mathbb{C}^N)$ are formulated. We set up the Landau problem in $\mathbf{Gr}_2(\mathbb{C}^N)$ and solve it using group theoretical techniques and provide the energy spectrum and the eigenstates in terms of the $SU(N)$ Wigner ${\cal D}$-functions for charged particles on $\mathbf{Gr}_2(\mathbb{C}^N)$ under the influence of abelian and non-abelian background magnetic monopoles or a combination of these thereof. In particular, for the simplest case of $\mathbf{Gr}_2(\mathbb{C}^4)$ we explicitly write down the $U(1)$ background gauge field as well as the single and many-particle eigenstates by introducing the Pl\"{u}cker coordinates and show by calculating the two-point correlation function that the Lowest Landau Level (LLL) at filling factor $\nu =1$ forms an incompressible fluid. Our results are in agreement with the previous results in the literature for QHE on ${\mathbb C}P^N$ and generalize them to all $\mathbf{Gr}_2(\mathbb{C}^N)$ in a suitable manner. Finally, we heuristically identify a relation between the $U(1)$ Hall effect on $\mathbf{Gr}_2(\mathbb{C}^4)$ and the Hall effect on the odd sphere $S^5$, which is yet to be investigated in detail, by appealing to the already known analogous relations between the Hall effects on ${\mathbb C}P^3$ and ${\mathbb C}P^7$ and those on the spheres $S^4$ and $S^8$, respectively.Comment: 34 pages, revtex 4-1, Minor Correction

The power of perturbation theory

We study quantum mechanical systems with a discrete spectrum. We show that the asymptotic series associated to certain paths of steepest-descent (Lefschetz thimbles) are Borel resummable to the full result. Using a geometrical approach based on the PicardLefschetz theory we characterize the conditions under which perturbative expansions lead to exact results. Even when such conditions are not met, we explain how to define a different perturbative expansion that reproduces the full answer without the need of transseries, i.e. non-perturbative effects, such as real (or complex) instantons. Applications to several quantum mechanical systems are presented

Dysgerminoma in three patients with Swyer syndrome

<p>Abstract</p> <p>Background</p> <p>Dysgerminoma is the most common malignant germ cell tumor of the ovary. This malignancy can be associated with pure gonadal dysgenesis or Swyer syndrome, mixed gonadal dysgenesis and partial gonadal dysgenesis.</p> <p>Case presentation</p> <p>Dysgerminoma developed in 3 phenotypic female patients with 46 XY pure gonadal dysgenesis. All patients presented first with abdominopelvic mass. Laparatomy was done. 46 XY karyotype was made by lymphocyte culture. Then these patients underwent gonadectomy that histopathology results were streak ovaries without evidence for malignancy. Two patients received postoperative adjuvant therapy.</p> <p>Conclusion</p> <p>In Patients with Swyer syndrome the risk of dysgerminoma is high and gonadectomy is recommended. Also 5% of dysgerminomas are discovered in phenotypic female and 46 XY karyotype, thus in adolescent with dysgerminoimas and amenorrhea, karyotype should be done.</p

Environmental morphing enables informed dispersal of the dandelion diaspore

Animal migration is highly sensitised to environmental cues, but plant dispersal is considered largely passive. The common dandelion, Taraxacum officinale, bears an intricate haired pappus facilitating flight. The pappus enables the formation of a separated vortex ring during flight; however, the pappus structure is not static but reversibly changes shape by closing in response to moisture. We hypothesised that this leads to changed dispersal properties in response to environmental conditions. Using wind tunnel experiments for flow visualisation, particle image velocimetry, and flight tests we characterised the fluid mechanics effects of the pappus morphing. We also modelled dispersal to understand the impact of pappus morphing on diaspore distribution. Pappus morphing dramatically alters the fluid mechanics of diaspore flight. We found that when the pappus closes in moist conditions, the drag coefficient decreases and thus the falling velocity is greatly increased. Detachment of diaspores from the parent plant also substantially decreases. The change in detachment when the pappus closes increases dispersal distances by reducing diaspore release when wind speeds are low. We propose that moisture-dependent pappus-morphing is a form of informed dispersal allowing rapid responses to changing conditions

Ovarian carcinoma associated with pregnancy: A clinicopathologic analysis of 23 cases and review of the literature

<p>Abstract</p> <p>Background</p> <p>The aim of this study was to analyze and describe cases of ovarian cancer in pregnant women treated at our center and to review the literature concerned, and to discuss the rationale for therapy.</p> <p>Methods</p> <p>Twenty-Three patients of ovarian malignancies during pregnancy were treated at Vali- Asr Hospital between 1991 and 2002. Data on treatment and follow-up were evaluated.</p> <p>Results</p> <p>The incidence of ovarian carcinoma associated with pregnancy in our series was 0.083/1000 deliveries. Eleven (47.8%) were found with ovarian malignant germ cell tumors, five (21.7%) with low malignant potential tumors, four (17.4%) with invasive epithelial tumors, and three (13%) with sex cord stromal tumors. Seventeen (73.9%) of the patients were diagnosed in stage I and had complete remission. Five of the six in advanced stage died. The mean follow-up was 36.3 months. The prognosis was significantly related with stage and histological type (<it>P </it>< 0.05). Sixteen healthy live babies were recorded in this group, and two premature newborn died of respiratory distress syndrome. Chemotherapy was administered to 44% of the patients, in two cases during pregnancy. Overall survival at 5 years was 61%. In most of case conservative surgical treatment could be performed with adequate staging and debulking.</p> <p>Conclusion</p> <p>Early finding of ascitis by ultrasound and persistent large ovarian mass during pregnancy may be related to malignancy and advanced stage. Pregnant women in advanced stage of ovarian cancer seem to have poor prognosis.</p