Fujita Exponent for Porous Medium Equation with Convection and Nonlinear Boundary Condition

This paper is concerned with the critical exponent of the porous medium equation with convection and nonlinear boundary condition. It is shown that the coefficient of the lower order term is an important factor that determines the critical exponent.

EXISTENCE OF INFINITELY MANY SOLUTIONS FOR ELLIPTIC PROBLEMS WITH CRITICAL EXPONENT

This paper is concerned with the following nonlinear Dirichlet problem:where △pu = div(| ▽u|p- 2 ▽u) is the p-Laplacian of u, Ω is a bounded domain in Rn (n > 3), 1 < p < n, p = -pn/n-p is the critical exponent for the Sobolev imbedding, λ > 0 and f(x, u) satisfies some conditions. It reaches the conclusion that this problem has infinitely many solutions. Some results as p = 2 or f(x,u) = |u|q-2u, where 1 < q < p, are generalized.

基于反演模型的焦炉无组织苯并[a]芘排放因子研究

由于焦炉无组织苯并[a]芘排放因子难以测量,导致了焦炉苯并[a]芘大气污染研究存在一定的不确定性.针对上述问题,本研究根据1999年~2003年上海某焦化厂的产量、空气质量监测等数据,建立了基于AERMOD(AMS/EPA REGULATORY MODEL)模型反演苯并[a]芘排放因子的方法.结果显示,企业周边3个监测点年平均浓度结果分别为0.033,0.0024,0.0031μg/m^3,均超过了2012年颁布的环境空气质量标准,通过AERMOD模型反演得到该焦化厂苯并[a]芘平均排放因子为14.71mg/t焦煤,苯并[a]芘预测浓度超标面积125km^2,超标区域主要集中在焦化厂周围,超标焦炉苯并[a]芘防护距离为6300m.

A Numerical Study of Second-Order Turbulent Moments in the Stably Stratified Nocturnal Boundary Layer

The structures and the vertical profiles of turbulent variance and covariance of the stably stratified boundary layer (SBL) are simulated with a second-order closure turbulence model. The results confirm that the vertical profiles of the dimensionless turbulence variance and covariance can be well represented by the form F = A(1 - Z / h)x. Here h is the height of SBL. and both exponent a and coefficient A are the functions of terrain, baroclinicity, radiation cooling and the state of temporal development of SBL. Comparing with Minnesota and Cabauw experiment data, we have analysed the value of a and expounded the main reasons that great difference in a exists among different literatures.

Shock tube design for high intensity blast waves for laboratory testing of armor and combat materiel

Shock tubes create simulated blast waves which can be directed and measured lo study blast wave effects under laboratory conditions.It is desirable to increase available peak pressure from ~1 MPa to ~5 MPa to simulate closer blast sources and facilitate development and testing of personal and vehicle armors.Three methods are experimentally investigated to increase peak simulated blast pressure produced by an oxyacetylene driven shock tube while maintaining suitability for laboratory studies.The first method is the addition of a Shchelkin spiral priming section which supports a deflagration to detonation transition.This approach increases the average peak pressure from 1.17 MPa to 5.33 MPa while maintaining a relevant pressure-time curve(near Friedlander waveform).The second method is a bottleneck between the driving and driven sections.Coupling a 79 mm diameter driving section to a 53 mm driven section increases the peak pressure from 1.17 MPa to 2.25 MPa.A 103 mm driving section is used to increase peak pressure to 2.64 MPa.The third method,adding solid fuel to the driving section with the oxyacetylene,results in a peak pressure increasing to 1.70 MPa.

Effects of cereal fiber on bowel function: A systematic review of intervention trials

AIM: To comprehensively review and quantitatively summarize results from intervention studies that examined the effects of intact cereal dietary fiber on parameters of bowel function. METHODS: A systematic literature search was conducted using Pub Med and EMBASE. Supplementary literature searches included screening reference lists from relevant studies and reviews. Eligible outcomes were stool wet and dry weight, percentage water in stools, stool frequency and consistency, and total transit time. Weighted regression analyses generated mean change(± SD) in these measures per g/d of dietary fiber. RESULTS: Sixty-five intervention studies among generally healthy populations were identified. A quantitative examination of the effects of non-wheat sources of intact cereal dietary fibers was not possible due to an insufficient number of studies. Weighted regression analyses demonstrated that each extra g/d of wheat fiber increased total stool weight by 3.7 ± 0.09 g/d(P < 0.0001; 95%CI: 3.50-3.84), dry stool weight by 0.75 ± 0.03 g/d(P < 0.0001; 95%CI: 0.69-0.82), and stool frequency by 0.004 ± 0.002 times/d(P = 0.0346; 95%CI: 0.0003-0.0078). Transittime decreased by 0.78 ± 0.13 h per additional g/d(P < 0.0001; 95%CI: 0.53-1.04) of wheat fiber among those with an initial transit time greater than 48 h.CONCLUSION: Wheat dietary fiber, and predominately wheat bran dietary fiber, improves measures of bowel function.

Nutritional and health benefits of semi-elemental diets: A comprehensive summary of the literature

AIM:To critically review and summarize the literature on nutritional and health outcomes of semi-elemental formulations on various nutritionally vulnerable patient populations who are unable to achieve adequate nutrition from standard oral diets.METHODS:We conducted a comprehensive literature search of Pubmed and Embase databases.We manually screened articles that examined nutritional and health outcomes(e.g.,growth,disease activity,gastrointestinal impairment,mortality,and economic impact)among various patient groups receiving semi-elemental diets.This review focused on full-text articles of randomized controlled clinical trials and other intervention studies,but pertinent abstracts and case studies were also included.Results pertaining primarily to tolerance,digestion,and absorption were summarized for each patient population in this systematic review.RESULTS:Results pertaining primarily to tolerance,digestion,and absorption were summarized for each patient population.The efficacy of semi-elemental whey hydrolyzed protein(WHP)diet have been reported in various nutritionally high risk patient populations including-Crohn’s disease,short bowel syndrome,acute and chronic pancreatitis,cerebral palsy,cystic fibrosis,cerebrovascular accidents,human immunodeficiency virus,critically ill,and geriatrics.Collectively,the evidence from the medical literature indicates that feeding with a semi-elemental diet performs as well or better than parenteral or amino acid based diets in terms of toler-ance,digestion,and nutrient assimilation measures across various disease conditions.CONCLUSION:Based on this comprehensive review of the literature,patient populations who have difficulty digesting or absorbing standard diets may be able to achieve improved health and nutritional outcomes through the use of semi-elemental WHP diets.

The Characteristics of Ground Flashes in Beijing and Lanzhou Regions

Over twenty thousand lightning location data obtained by using Lightning Location System(LLS) from Lanzhou and Beijing regions have been analysed to ascertain the characteristics of ground flashes in both regions. The strength of positive flashes is 5 times higher in Lanzhou than in Beijing. The strength of positive flashes is 3 times and 2.2 times as large as negative flashes in Beijing and in Lanzhou respectively. It has been found that the strength of positive and negative flashes is submitted to the normal distribution, and is independent of the characteristics of thunderstorm. So the lightning strength obtained by DF may be used to forecast the coming of thunderstorm. Although the stroke number in both regions decreases as exponent regulation, the maximum number of return stroke for one lightning in Beijing is more than that in Lanzhou. The peak flash rate occurs in late afternoon for both regions, but the maximum and minimum flash rate appeared an hour earlier in Beijing than in Lanzhou.The relationship between DF display and lightning radiation electric field, discharge current is obtained.

A Modified Mixing Rule for PSRK Model and Application for the Prediction of Vapor-Liquid Equilibria of Polymer Solutions

To extend the PSRK (predictive Soave-Redlich-Kwong equation of state) model to vapor-liquid equilibria of polymer solutions, a new EOS-gE mixing rule is applied in which the term ∑ xi ln(b/bi) in the PSRK mixing rule for the parameter a, and the combinatorial part in the original universal functional activity coefficient (UNIFAC) model are cancelled. To take into account the free volume contribution to the excess Gibbs energy in polymer solution, a quadratic mixing rule for the cross co-volume bij with an exponent equals to 1/2 is applied[bij1/2= 1/2(bi1/2+bj1/2)]. The literature reported Soave-Redlich-Kwong equation of state (SRK EOS) parameters ofpure polymer are employed. The PSRK model with the modified mixing rule is used to predict the vapor-liquid equilibrium (VLE) of 37 solvent-polymer systems over a large range of temperature and pressure with satisfactory results.

A new prognostic histopathologic classification of nasopharyngeal carcinoma

Background:The current World Health Organization(WHO) classification of nasopharyngeal carcinoma(NPC) con?veys little prognostic information.This study aimed to propose an NPC histopathologic classification that can poten?tially be used to predict prognosis and treatment response.Methods:We initially developed a histopathologic classification based on the morphologic traits and cell differentia?tion of tumors of 2716 NPC patients who were identified at Sun Yat?sen University Cancer Center(SYSUCC)(training cohort).Then,the proposed classification was applied to 1702 patients(retrospective validation cohort) from hospitals outside SYSUCC and 1613 patients(prospective validation cohort) from SYSUCC.The efficacy of radiochemotherapy and radiotherapy modalities was compared between the proposed subtypes.We used Cox proportional hazards models to estimate hazard ratios(HRs) with 95% confidence intervals(CI) for overall survival(OS).Results:The 5?year OS rates for all NPC patients who were diagnosed with epithelial carcinoma(EC;3708 patients),mixed sarcomatoid?epithelial carcinoma(MSEC;1247 patients),sarcomatoid carcinoma(SC;823 patients),and squamous cell carcinoma(SCC;253 patients) were 79.4%,70.5%,59.6%,and 42.6%,respectively(P < 0.001).In mul?tivariate models,patients with MSEC had a shorter OS than patients with EC(HR = 1.44,95% CI = 1.27–1.62),SC(HR = 2.00,95% CI = 1.76–2.28),or SCC(HR = 4.23,95% CI = 3.34–5.38).Radiochemotherapy significantly improved survival compared with radiotherapy alone for patients with EC(HR 49–0.75),and possibly for those with SCC(HR = 0.67,95% CI = 0.56–0.80),MSEC(HR = 0.58,95% CI = 0..74–1.28).= 0.63;95% CI = 0.40–0.98),but not for patients with SC(HR = 0.97,95% CI = 0Conclusions:The proposed classification offers more information for the prediction of NPC prognosis compared with the WHO classification and might be a valuable tool to guide treatment decisions for subtypes that are associ?ated with a poor prognosis.

Objective-level resilience assessment of circular roadway tunnels with reinforced concrete liners for vehicle fire hazards

A framework is presented to quantify the objective-level resilience of reinforced concrete liners of circular tunnels when exposed to enclosed vehicle fire hazards.By assessing the loss of functionality due to fire-induced damage,the framework enables a decision-basis evaluation of the efficiency of various fire mitigation methods for spe-cific tunnel conditions.In this study,the fire-induced damage of concrete tunnel liners due to strength loss and spalling is stochastically simulated and classified based on typical post-fire repair procedures and damage evalu-ation.The resilience assessment is conducted using Monte Carlo Simulation in combination with a fast-running tool for calculating the thermal impact from vehicle fires on the inside surface of the tunnel liner(developed by the authors in previous work).The proposed approach accounts for uncertainties associated with both the vehicle fire(particularly the combustion energy)and the tunnel conditions(i.e.,geometry,dimensions,and the presence of longitudinal ventilation and/or fixed fire-fighting systems(FFFS)).A parametric case study is used to quantitatively demonstrate the effectiveness of FFFS for reducing post-fire losses of tunnel functionality.Other parameters such as tunnel dimensions,traffic restrictions for vehicles with heavy fire hazard risk,and installation or upgrade of the tunnel ventilation system show somewhat less effectiveness for reducing fire-induced damage.

Stressor analysis approaches for endangered species assessments

The US Endangered Species Act is legislation with the power to limit human activities that may have deleterious effects on the viability of threatened and endangered species of fauna and flora. However, because most endangered species face multiple threats, it is often unclear whether limiting specific activities will improve the likelihood of long-term survival, particularly when the relative importance of different stressors is uncertain. Wildlife managers responsible for protecting these species face the challenge of determining the optimal allocation of limited funds and personnel among risk management and conservation priorities, in the absence of a good understanding of the relative importance of these stressors. We present an analytical framework that can serve as a technical basis for evaluating multiple risks to endangered species. Predictive and retrospective causal analysis applications are considered. The former address proposed projects where the potential exists for adverse interaction between the project and an endangered species. The latter involve existing projects or products for which a determination is being or has been made concerning the threats posed to an endangered species. The causal analysis method described herein is a well-established procedure that is widely used in other scientific fields and offers a practical and logical process through which threats to endangered species can be assessed and recovery actions prioritized.

A Study of the Mechanical Characteristics of a Mandibular Parasymphyseal Fracture with Internal Fixation Device Subject to Variable Bite Forces: Finite Element Analysis

In recent times, research into mandibular fracture has gained momentum from advances in scanning techniques, software/algorithm developments and improvements, and numerical structural modeling using the finite-element method (FEM). In this work, the FEM is used to model a mandibular fracture (using an inhomogeneous and orthotropic jaw model) simulating the effect of different bite tasks/forces on the stability of the fixated fracture. Specifically, bilateral and unilateral clenches (using muscle data) were studied using a low-profile 3D 4 × 2 hole mini-plate deployed for fracture fixation. Here, the mandible bone was treated as orthotropic and spatially inhomogeneous. Although the results of stress and displacement analyses, for this fixation hardware, indicate sufficient fixation under normal biting conditions, the results show that the unilateral and ipsilateral bites develop, in general, the highest stresses or displacements. Such results can guide post-surgery recommendation on bite behavior.

Left Atrial Appendage Occlusion Device: Evaluation of Surgical Implant Success and <i>in Vivo</i>Corrosion Performance

Objective: The purpose of this study was to compare the in vivo corrosion resistance of the implanted titanium, nitinol annular occlusion device to a control device, i.e. an implantable device containing nitinol, approved by the FDA and currently on the market. Methods: The annular occlusion device is a self-closing, implantable clip. Three canines underwent placement of devices on the left and right atrial appendages. Two Vnus U-clips were secured to either atrium. On post-operative day 95, animals underwent en-bloc cardiac resection via the previous left thoracotomy incision. The annular occlusion device and U-clips were dissected free from the atria. The polyester fabric and tissue ingrowth were removed from the devices and were sent for corrosion analysis. Results: Gross examination of resected hearts of two canines revealed no abnormalities. The compressed endocardial surfaces were completely fused and the appendages fully necrosed. All devices were located and harvested. The annular occlusion device clips and Medtronic Vnus U-clips were evaluated using scanning electron microscopy. Both low and high magnification examination of the nitinol springs and the site of insertion of the nitinol springs into the titanium tubes in the annular occlusion device showed no evidence of localized corrosion. In no case was any evidence of general or localized corrosion found in the form of metallic oxidation. Conclusion: The annular occlusion device provides safe and reliable exclusion of the left atrial ap-pendage without evidence of general or localized corrosion over the 95-day exposure period in canines and may therefore provide a reasonable therapeutic option for stroke risk reduction in patients with atrial fibrillation.

Development of an instrument to identify symptoms potentially indicative of ovarian cancer in a primary care clinic setting

Background: Several recently published studies suggest that screening for symptoms could improve the early diagnosis of ovarian cancer. This report describes the development of a simple and reliable method of collecting symptom information in a primary care clinic. Methods: 1200 women, ages 40 - 87, completed several versions of a draft symptom index (SI) assessment form during their visits to a primary care clinic. Factors associated with a positive SI result were examined. Providers were surveyed about acceptability of the symptom screening procedures. Findings: Variation in the instructions provided to women influenced the rate at which women indicated having symptoms indicative of a positive SI, 5% had positive results when written instructions emphasized listing only current symptoms. Women coming to the clinic because of a current medical concern or problem did have higher rates of positive SI results, as did non-white women (p < 0.05). Acceptability by providers was high. Patients could independently complete the SI in under 5 minutes. One patient with a positive SI was diagnosed with ovarian cancer and none with a negative SI developed cancer. Interpretation: A quick paper and pencil form can be used to identify women with symptoms potentially indicative of ovarian cancer. Use of such a form for ovarian cancer screening purposes is acceptable to most women and providers in a primary care clinic setting.

BIFURCATION AND CHAOS OF THE CIRCULAR PLATES ON THE NONLINEAR ELASTIC FOUNDATION

According to the large amplitude equation of the circular plate on nonlinear elastic foundation , elastic resisting force has linear item , cubic nonlinear item and resisting bend elastic item. A nonlinear vibration equation is obtained with the method of Galerkin under the condition of fixed boundary. Floquet exponent at equilibrium point is obtained without external excitation. Its stability and condition of possible bifurcation is analysed. Possible chaotic vibration is analysed and studied with the method of Melnikov with external excitation . The critical curves of the chaotic region and phase figure under some foundation parameters are obtained with the method of digital artificial.

Saudi Arabia＇s Growing Demand for Electricity： Some Strategic Recommendations

Demand for electricity in Saudi Arabia is growing at a significant annual rate of nearly 8%. It is expected that, by 2030, the demand will increase to about 120 GW per year, approximately three times the 2010 load. Satisfying this demand will require a significant investment in the power grid at an estimated cost, over the next 10 years, ofSAR （Saudi Arabia Riyal） 500 billion. Existing power plants rely on oil and natural gas, it is anticipated that meeting the demand in 2030 will consume 3 million barrels ofoil each day, which significantly impacting the economy by reducing the country＇s income from oil exports, which is a hot button for Saudi decision makers. This paper reviews the responses of various countries in meeting their loads, and therefore, draws recommendations for some resources that should, and should not, be considered best-candidate options for Saudi Arabia economically, technically and environmentally. The discussion primarily examines renewable and nuclear resources.

Seismic collapse assessment of archetype frames with ductile concrete beam hinges

Highly ductile cement-based materials have emerged as alternatives to conventional concrete materials to improve the seismic resistance of reinforced concrete(RC)structures.While experimental and numerical research on the behavior of individual components has provided significant knowledge on element-level response,relatively little is known about how ductile cement-based materials influence system-level behavior in seismic applications.This study uses recently developed lumped-plasticity models to simulate the unique failure characteristics and ductility of reinforced ductile-cement-based materials in beam hinges and applies them in the assessment of archetype frame structures.Numerous story heights(four,eight,and twelve),frame configurations(perimeter vs.space),materials(conventional vs.ductile concrete),and replacement mechanisms within the beam hinges are considered in the seismic analysis of the archetype structures.Results and comparisons are made in terms of the probability of collapse at 2%in 50-year ground motion,mean annual frequency of collapse,and adjusted collapse margin ratio(ACMR)across archetype structures.The results show that engineered HPFRCCs in beam plastic-hinge regions can improve the seismic safety of moment frame buildings with higher collapse margin ratios,lower probability of collapse,and the ability to withstand large deformations.Data is also reported on how ductile concrete materials can reduce concrete volume and longitudinal reinforcement tonnage across frame configurations and story heights while maintaining or improving seismic resistance of the structural system.Results demonstrate future research needs to assess life-cycle costs,predict column hinge behavior,and develop code-based design methods for structural systems using highly ductile concrete materials.

A PROPERTY OF STABLE LAWS

Let V_α denote a stable law by the characteristic exponent a (0<α≤2). It is well known that if the distribution function F(x) belongs to the domain of

美国全髋置换关节负重面应用的流行情况调研

背景：硬性对硬性材料的负重面有提高全髋关节置换假体植入物生存的潜力。然而，对于使用这些先进技术的特定适应证仍然存在争议。本研究的日的是从患者、医院、地域和支付人特点几方面对美国全髋关节置换中负重面应用情况进行流行病学研究。方法：应用全国住院病例数据库资料，对从2005年10月1日至2006年12月31日，在美国进行的112095例初次全髋关节置换病例的负重面类型及其人口统计学特征进行分析。病例按照年龄、性别、普查区域、付款人类别和医院的类型进行分组，计算每种类型髋关节负重面在各组中的使用率。