We discuss elastic-brittle fracture theory for cracks along interfaces between elastically dissimilar solids. Crack tip fields in such cases are characterized by one real and one complex stress intensity factor, where the latter couples two of the classically separate crack tip modes. Solutions for complex stress intensity factors for a variety of cases, including geometries of interest for toughness testing, are cataloged and the theory is applied to the problem of dislocation nucleation from a crack tip along a dissimilar material interface, such as a metal/ceramic interface. The variation of the-local phase angle, indicating stress field mode coupling, at the near atomic scale of dislocation nucleation is an important aspect of the problem. The dislocation problem arises in evaluating the competition between atomically brittle decohesion and plastic blunting at interfacial crack tips. Results confirm that both the properties of the interface and the direction of attempted cracking along it are important to the outcome of that competition; the latter arises because of the different stressing of slip systems associated with different directions of cracking. We also briefly review effects of solute adsorption at ceramic and metal/ceramic interfaces on their embrittlement, or in some cases on their ductilizing. Finally, we outline the thermodynamic inter relations between adsorption and alterations of the ideal work of interfacial separation, and formulate the. thermodynamic theory in a manner consistent with the possibility of strong dissimilarity in adsorption properties of the tWo surfaces which joined at the interface before fracture.
OBJECTIVE— The aim of this study was to examine the relationship between type 1 and type 2 diabetes and risk of stroke subtypes in women. RESEARCH DESIGN AND METHODS— We followed 116,316 women aged 30–55 years in 1976 through 2002 for incidence of stroke. At baseline and through biennial follow-up, women were asked about their history and treatment of diabetes and other potential risk factors for stroke. RESULTS— During 2.87 million person-years of follow-up, 3,463 incident strokes occurred. In multivariate analyses, the incidence of total stroke was fourfold higher in women with type 1 diabetes (relative risk [RR] 4.7 [95% CI 3.3–6.6]) and twofold higher among women with type 2 diabetes (1.8 [1.7–2.0]) than for nondiabetic women. The multivariate RR of ischemic stroke was increased sixfold (6.3 [4.0–9.8]) in type 1 diabetes and twofold (2.3 [2.0–2.6]) in type 2 diabetes. Risks for large-artery infarction and lacunar stroke were similar. Type 1 diabetes was also significantly associated with the risk of hemorrhagic stroke (3.8 [1.2–11.8]), but type 2 diabetes was not (1.0 [0.7–1.4]). CONCLUSIONS— Both type 1 and type 2 diabetes are associated with substantially increased risks of total and most subtypes of stroke.
Obesity has become a global epidemic. This chapter provides an overview of major risk factors of obesity, including those that are specifically relevant to women of reproductive age. Available data support the roles of unhealthful food choices, a sedentary lifestyle, and inadequate sleep duration in the occurrence of weight gain and obesity. Child bearing related factors such as parity, lactation, breastfeeding, gestational weight gain, and postpartum weight retention also play an important role in long-term weight gain among women. The etiology of obesity also has a genetic component. Research is needed in the most effective ways to prevent weight gain through improving diet and lifestyle, and promoting breastfeeding among women of reproductive age, including individual behavioral changes and creation of a supportive social environment. Minimizing gestational weight gain and reducing weight retention after pregnancy appear to be attractive public health interventions to reduce weight gain or obesity for women.
An examination of semiconductor nanowires focused on their fundamental properties and applications in nanoelectronics is presented. First, the transport properties of silicon and germanium/silicon nanowires are described with an emphasis on coherent and ballistic transport. Second, strategies for integrating controlled nanoscale metal-semiconductor junctions, and the properties of single devices and large areas are reviewed. Third, applications of these nanowires device arrays, such as bioelectronic detectors, are described, and strategies for integrated systems are discussed.
No abstract is provided for this article.
Objectives. We investigated Black–White differences in the association between average alcohol drinking patterns and all-cause mortality. Methods. We pooled nationally representative samples of 152 180 adults in the National Health Interview Survey from 1997 to 2002 with mortality follow-up through 2006. Usual drinking days per week and level of alcohol consumed per day were based on self-report. We used race- and gender-specific Cox proportional hazards regression analyses to adjust for physical activity, smoking status, and other potential confounders. Results. Over 9 years, 13 366 deaths occurred from all causes. For men, the lowest multivariable-adjusted hazard ratio (HR) for total mortality among drinkers was 0.81 among White men who consumed 1 to 2 drinks 3 to 7 days per week (compared with abstainers) and Black men who abstained. For women, the lowest mortality risk was among White women (HR = 0.71) consuming 1 drink per day 3 to 7 days per week and Black women (HR = 0.72) consuming 1 drink on 2 or fewer days per week. Conclusions. Risks and benefits of alcohol consumption in relation to mortality risk were dependent on race- and gender-specific drinking patterns.
Nanoscience offers the promise of producing revolutionary advances in many areas of technology, ranging from electronics and computing to biology and medicine, and thus may impact in a substantial way our future lives. This presentation will provide an overview to the bottom-up paradigm for nanotechnology enabled using nanowire building blocks. First, the growth of nanowires, with composition controlled down to the atomic scale, their fundamental electronic properties, and the assembly of integrated structures will be described. Second, studies of nanowire based electronic circuits and nanocomputing systems will be critically examined. Third, nanowire devices configured as electrically-based biosensors will be discussed with an emphasis on disease detection and ultimate sensitivity limits of these nanodevices, as well as the potential linkage to biological information processing. Challenges and goals that must be met to realize these and other nanotechnologies in the future will be discussed.
n engl j med 370;14 nejm.org april 3, 2014 1364 association between BMI and mortality was similar in persons with a high level of physical activity and those with a low level (P = 0.19 for interaction in women and P = 0.37 for interaction in men). In a previous study, we found that BMI and physical activity were independently associated with the risk of death.1 In the Aerobics Center Longitudinal Study, a high BMI was the most important modifiable risk factor for low cardiorespiratory fitness, and obesity was found to offset the benefits of physical activity on fitness.2 Furthermore, weight loss through lifestyle interventions was highly effective in improving physical fitness.3 In response to Logue et al.: although our Nurses’ Health Study and Health Professionals Follow-up Study cohorts were enrolled in 1976 and 1986, respectively, our analyses included incident diabetes cases through January 1, 2010. Thus, our cohorts reflected contemporary populations of patients with diabetes. Because body weight is substantially influenced by disease severity and methods of treatment, it is important to use BMI before or at the time of a diabetes diagnosis. As shown in our data and those of others, weight loss is common in patients with diabetes, even shortly before the diagnosis. Therefore, use of the postdiagnosis weight increases the potential for reverse-causation biases. Dixon and Kral note that overweight and obesity might be protective against premature death in older populations by providing metabolic reserves, although this hypothesis has yet to be tested. However, among older participants (≥65 years of age) at diabetes diagnosis, we found no survival advantage associated with overweight or obesity. BMI is a less valid measure of excess body fat in elderly populations than in younger populations, owing to differential loss of muscle mass related to sarcopenia and increased frailty. Future studies involving elderly populations should pay particular attention to these methodologic issues, especially weight loss due to chronic diseases, and should also include measures of bodyfat distribution such as waist circumference.
