Integral Equations with Hypersingular Kernels -- Theory and Applications to Fracture Mechanics

Hypersingular integrals of the type I_{\alpha}(T_n,m,r) = \int_{-1}^{1} \hpsngAbs \frac{T_n(s)(1-s^2)^{m-{1/2}}}{(s-r)^\alpha}ds |r|<1 and I_{\alpha}(U_n,m,r) = \int_{-1}^{1} \hpsngAbs \frac{U_n(s)(1-s^2)^{m-{1/2}}}{(s-r)^\alpha}ds |r|<1 are investigated for general integers $\alpha$ (positive) and $m$ (non-negative), where $T_n(s)$ and $U_n(s)$ are the Tchebyshev polynomials of the 1st and 2nd kinds, respectively. Exact formulas are derived for the cases $\alpha = 1, 2, 3, 4$ and $m = 0, 1, 2, 3$; most of them corresponding to new solutions derived in this paper. Moreover, a systematic approach for evaluating these integrals when $\alpha > 4$ and $m>3$ is provided. The integrals are also evaluated as $|r|>1$ in order to calculate stress intensity factors (SIFs). Examples involving crack problems are given and discussed with emphasis on the linkage between mathematics and mechanics of fracture. The examples include classical linear elastic fracture mechanics (LEFM), functionally graded materials (FGM), and gradient elasticity theory. An appendix, with closed form solutions for a broad class of integrals, supplements the paper

An efficient and positivity-preserving layer method for modeling radiation belt diffusion processes

An efficient and positivity-preserving layer method is introduced to solve the radiation belt diffusion equation and is applied to study the bounce resonance interaction between relativistic electrons and magnetosonic waves. The layer method with linear interpolation, denoted by LM-L (layer method-linear), requires the use of a large number of grid points to ensure accurate solutions. We introduce a monotonicity- and positivity-preserving cubic interpolation method to be used with the Milstein-Tretyakov layer method. The resulting method, called LM-MC (layer method-monotone cubic), can be used to solve the radiation belt diffusion equation with a much smaller number of grid points than LM-L while still being able to preserve the positivity of the solution. We suggest that LM-MC can be used to study long-term dynamics of radiation belts. We then develop a 2-D LM-MC code and use it to investigate the bounce resonance diffusion of radiation belt electrons by magnetosonic waves. Using a previously published magnetosonic wave model, we demonstrate that bounce resonance with magnetosonic waves is as important as gyroresonance; both can cause several orders of magnitude increase of MeV electron fluxes within 1ﾠday. We conclude that bounce resonance with magnetosonic waves should be taken into consideration together with gyroresonance

Substantial improvements not seen in health behaviors following corner store conversions in two Latino food swamps.

BackgroundThe effectiveness of food retail interventions is largely undetermined, yet substantial investments have been made to improve access to healthy foods in food deserts and swamps via grocery and corner store interventions. This study evaluated the effects of corner store conversions in East Los Angeles and Boyle Heights, California on perceived accessibility of healthy foods, perceptions of corner stores, store patronage, food purchasing, and eating behaviors.MethodsHousehold data (n = 1686) were collected at baseline and 12- to 24-months post-intervention among residents surrounding eight stores, three of which implemented a multi-faceted intervention and five of which were comparisons. Bivariate analyses and logistic and linear regressions were employed to assess differences in time, treatment, and the interaction between time and treatment to determine the effectiveness of this intervention.ResultsImprovements were found in perceived healthy food accessibility and perceptions of corner stores. No changes were found, however, in store patronage, purchasing, or consumption of fruits and vegetables.ConclusionsResults suggest limited effectiveness of food retail interventions on improving health behaviors. Future research should focus on other strategies to reduce community-level obesity

Comparative study of governments’ reasons/motivations for adopting public-private partnership policy in developing and developed economies/countries

Over the last couple of decades, governments in developing and developed economies/countries have shown interest in the public-private partnership (PPP) policy. Different governments have different reasons for adopting the PPP concept. This paper aims to investigate the differences and similarities on the reasons for implementing PPP in develop-ing and developed economies/countries, represented by Ghana and Hong Kong. An empirical questionnaire survey was conducted with relevant experienced practitioners in both jurisdictions. One hundred and three completed questionnaires were returned for analysis. The results from the non-parametric test show five reasons with significant differences. Reasons related to the economic and social benefits of PPP are ranked higher in Ghana, whereas efficiency and quality service related reasons are ranked higher in Hong Kong. Further, two reasons for adopting PPP emerged as very important in both jurisdictions; these include: “promotes quick delivery of public infrastructure projects” and “allows for shared risks”. The outputs of this study contribute to the international best practice framework for PPP. International private investors would be informed of the expectations of governments when engaging in PPP arrangement particularly in Asia and Africa

Stereotactic ablative radiotherapy for medically inoperable early stage lung cancer: early outcomes

Objective To evaluate the clinical outcome and safety of stereotactic ablative radiotherapy for medically inoperable stage I non- small-cell lung carcinoma. Design Retrospective case series. Setting Pamela Youde Nethersole Eastern Hospital, Hong Kong. Patients All patients with medically inoperable stage I non-small-cell lung carcinoma receiving stereotactic ablative radiotherapy since its establishment in 2008. Main outcome measures Disease control rate, overall survival, and treatment toxicities. Results Sixteen stage I non-small-cell lung carcinoma patients underwent the procedure from June 2008 to November 2011. The median patient age was 82 years and the majority (81%) had moderate-tosevere co-morbidity based on the Adult Comorbidity Evaluation 27 index. With a median follow-up of 22 months, the 2-year primary tumour control rate, disease-free survival and overall survival rates were 91%, 71% and 87%, respectively. No grade 3 (National Cancer Institute Common Terminology Criteria for Adverse Events) or higher treatment-related complications were reported. Conclusion Stereotactic ablative radiotherapy can achieve a high degree of local control safely in medically inoperable patients with early lung cancer.published_or_final_versio

Survival Analysis of Re-resection Versus Radiofrequency Ablation for Intrahepatic Recurrence After Hepatectomy for Hepatocellular Carcinoma

Ó The Author(s) 2011. This article is published with open access at Springerlink.com Background Tumor recurrence after resection of hepatocellular carcinoma is a common phenomenon. Re-resection and radiofrequency ablation (RFA) are good options for treating recurrent HCC. This study compared the efficacy of these two modalities in the treatment of intrahepatic HCC recurrence after hepatectomy. Methods From January 2001 to December 2008, a total of 179 patients developed intrahepatic HCC recurrence after hepatectomy. To treat the recurrence, 29 patients underwent re-resection and 45 patients had RFA. Patient characteristics, clinicopathologic data, and survival outcomes were reviewed. Results Child-Pugh status, time to develop first recurrence (12.2 vs. 8.7 months), and recurrent tumor size (2.1 vs. 2.1 cm) were comparable for the two groups. Time to develop a second intrahepatic recurrence after re-resection and RFA was 5.9 and 4.0 months respectively. The 1-, 3-, and 5-year disease-free survival rates were 41.4%, 24.2%, and 24.2 % after re-resection and 32.2%, 12.4%, and 9.3% after RFA (p = 0.14). The 1-, 3-, and 5-year overall survival rates were 89.7%, 56.5%, and 35.2 % after re-resection and 83.7%, 43.1%, and 29.1 % after RFA (p = 0.48). For the second recurrence, 33.3 % of patients underwent a second round of RFA and 10.0 % underwent a third resection

Single-Electron Spectroscopy

Contains research goals and objectives, reports on four research projects and a list of publications.Joint Services Electronics Program Contract DAAL03-92-C-0001Joint Services Electronics Program Grant DAAH04-95-1-0038National Science Foundation Young Investigator AwardPackard FoundationU.S. Navy - Office of Naval Researc

Cavity Design and Optimization for Organic Microcavity OLEDs

We report on detailed simulations of the emission from microcavity OLEDs consisting of widely used organic materials, n,N'-di(naphthalene-1-yl)-N,N'-diphenyl-benzidine (NPB) as a hole transport layer and tris (8-hydroxyquinoline) (Alq3) as emitting and electron transporting layer. The thick silver film was considered as a top mirror, while silver or copper films on quartz substrate were considered as bottom mirrors. The electroluminescence emission spectra, electric field distribution inside the device, carrier density and recombination rate were calculated as a function of the position of the emission layer, i.e. interface between NPB and Alq3. In order to achieve optimum emission from a microcavity OLED, it is necessary to align the position of the recombination region with the antinode of the standing wave inside the cavity. Once the optimum structure has been determined, the microcavity OLED devices were fabricated and characterized. The experimental results have been compared to the simulations and the influence of the emission region width and position on the performance of microcavity OLEDs was discussed

Measuring cognitive assessment and intervention burden in patients with acquired brain injured: Development of the "How Much is Too Much" questionnaire

Objective: To design and preliminarily test a questionnaire intended to measure patient treatment burden resulting from participation in cognitive assessments and interventions. Methods: An expert consensus process was used to develop the concept of patient treatment burden and to determine the first set of questionnaire items and administration protocol. The pilot questionnaire was administered to 20 patients with mild to severe acquired brain injuries on completion of a 2-h or longer neuropsychological assessment. Following preliminary testing, the questionnaire was revised and re-evaluated by a second expert panel and content validity was assessed. Results: Burden was defined as psychologically and/or physically aversive symptoms in response to cognitive assessment or intervention. The first questionnaire contained 21 items assigned to 3 categories: physical, cognitive, and emotional. Eightyfive percent of patients endorsed symptom level increases, with "tired/fatigued" the most frequently endorsed item (80% of patients). Instructions and test items were easily understood, and the questionnaire was quick to administer. Content validity ratio (CVR) of the revised questionnaire yielded 23 acceptable items and a subset met the highest CVR threshold (>0.78). Conclusion: This patient-reported outcome will ultimately help patients give voice to aversive experiences, and help clinicians and researchers to monitor and adapt assessments/treatments appropriately. Future steps in development are described

Lifecycle performance measurement of public-private partnerships: a case study in China’s water sector

Numerous public-private partnership (PPP) infrastructure projects have been operating in China after nearly 30 years of development. Surprisingly, few lessons and experiences have been drawn from these existing cases, thereby creating an urgent demand for a comprehensive evaluation of their performance. Thus, this paper presents a timely contribution to the assessment of a representative PPP project in China’s water sector, the Chengdu No. 6 Water Plant B Project, from a lifecycle perspective. Through a triangulation method, the project is generally deemed a success providing instructive lessons on the future evolutionary development of PPPs in China despite several imperfections caused by particular historical factors. Moreover, this paper advances the performance measurement of PPPs offering empirical insights to promote the efficacy of conceptual performance measurement frameworks. The outcomes of this research are especially valuable to the current Chinese PPP community where huge opportunities and challenges simultaneously exist