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This book contains the proceedings of a symposium sponsored by the Structural Materials, Physical Metallurgy, and Mechanical Metallurgy Committee of The Metallurgical Society. Some of the titles of the papers include: Fundamentals of Fracture and Fatigue: A Basis for Alloy Design, The Design of Tough Ferritic Steels for Cryogenic Use, Grain Boundary Segregation and Environmentally Induced Fracture Materials, and The Design of Low-Alloy Steels for Thick-Wall Pressure Vessels.
Diterpenes are a structurally diverse class of molecules common in plants, although they are very rarely found in bacteria. We report the identification in Mycobacterium tuberculosis ( Mtb ) of three diterpenes proposed to promote phagolysosome maturation arrest. MS analysis reveals that these diterpenes are novel compounds not previously identified in other organisms. The diterpene with highest abundance in Mtb has a mass fragmentation pattern identical to edaxadiene, which is produced in vitro from geranylgeranyl diphosphate by the enzymes Rv3377c and Rv3378c. A second diterpene found in Mtb has a similar mass spectrum, and is always observed in the same proportion relative to edaxadiene, indicating that it is a side product of the Rv3378c reaction in vivo . We name this second diterpene olefin edaxadiene B. The least abundant of the three diterpenes in Mtb extracts is tuberculosinol, a dephosphorylated side‐product of the edaxadiene pathway intermediate produced by Rv3377c . A frameshift in Rv3377c in Mtb completely eliminates diterpene production, whereas expression of Rv3377c and Rv3378c in the nonpathogenic M. smegmatis is sufficient to produce edaxadiene and edaxadiene B. These studies define the pathway of edaxadiene and edaxadiene B biosynthesis in vivo . Rv3377c and Rv3378c are unique to Mtb and M. bovis , making them candidates for selective therapeutics and diagnostics.
Abstract Fossil fuel alternatives, such as solar energy, are moving to the forefront in a variety of research fields. Polymer‐based organic photovoltaic systems hold the promise for a cost‐effective, lightweight solar energy conversion platform, which could benefit from simple solution processing of the active layer. The function of such excitonic solar cells is based on photoinduced electron transfer from a donor to an acceptor. Fullerenes have become the ubiquitous acceptors because of their high electron affinity and ability to transport charge effectively. The most effective solar cells have been made from bicontinuous polymer–fullerene composites, or so‐called bulk heterojunctions. The best solar cells currently achieve an efficiency of about 5 %, thus significant advances in the fundamental understanding of the complex interplay between the active layer morphology and electronic properties are required if this technology is to find viable application.
Abstract Review: 77 refs.
A.C. Buehler Distinguished Professor of Health Services Management, J. L. Kellogg Graduate School of Management, Northwestern University
Discussions within gerontology of family solidarity between generations have tended to focus on critical role of adult children, and particularly daughters and daughters-in-law, as informal caregivers to disabled elderly. Largely overlooked in such discussions, until recently, has been another group of cross-generational caregiversthe growing number of mid-life and older grandparents who are raising some of nation's most vulnerable children. Yet in many wa)s, such caregiving provides quintessential example of family transfers and family solidarity. Although grandparents often step in as surrogate parents as a consequence of breakdowns in a family's social compact (e.g., when their teenage or adult children prove unable or unwilling to provide to their own children), very fact that they do step in to keep family together is a classic example of family resilience in face of often substantial obstacles. Grandparents raising grandchildren is not new: Grandparents have always served as the family watchdogs (Troll, I985) and the second line of defense for children (Kornhaber, I985) in times of crisis. But what is new is rapid growth in this phenomenon, with close to a 4 percent increase in number of children living with grandparents and other relatives between I98o and I99o, and continued, albeit somewhat slower growth through I99os (Saluter, I992; Casper and Bryson, I998). By I997, close to 4 million children, or 5.5 percent of all children in United States, lived in a household headed by a grandparent (Lugaila, in press). In approximately one-third of homes, neither of child's biological parents is present, and number of these skipped generation families continues to grow at a rapid rate (Casper and Bryson, I998). More than one in ten grandparents (Io.9 percent) at some point raise a grandchild for at least six months, and typically for far longer periods of time (Fuller-Thomson, Minkler, and Driver, I997). This paper includes a brief profile of America's grandparent caregivers and a review of causes of increase in intergenerational households headed by grandparents as well as some of challenges it entails for grandparents and their families. The paper also describes development of supportive services for grandparent caregivers and their families, highlighting several model program efforts across country, and looks at need for supportive policies that assist-rather than penalize-the growing number of intergenerational families headed by grandparents. PROFILE OF GRANDPARENT CAREGIVERS Who are America's caregiving grandparents and what do we know about children in their care? Although media accounts have tended to focus on single, low-income African-American women raising their grandchildren, recent national studies suggest that typical grandparent raising a grandchild is a white married woman living above poverty line. Nationally, slightly more than half of grandparent caregivers are married (54 percent) and more than three quarters (77 percent) are women (FullerThomson, Minkler, and Driver, I997). However, being single, living in poverty, and being an African American do substantially increase odds of becoming a caregiver for one's grandchildren. For example, African-American children are four to five times more likely than non-Hispanic white children to be living in kinship care households-those in which children have been formally placed with their grandparents or other relatives (Harden, Clark, and Maguire, I997) -a fact reflecting both current socioeconomic realities and a long history of caregiving across generations in black families (Burton and Dilworth-Anderson, I99I). Although not as prevalent as in African American families, among Latinos, grandparent caregiving also appears more common, with 6.5 percent of Hispanic children (compared to 4.I percent of whites and I3.5 percent of African Americans) living with grandparents or other relatives (Lugaila, in press). …
Intrusive imagery was investigated in survivors of motor vehicle accidents with (a) posttraumatic stress disorder (PTSD) and accurate recall of the trauma, (b) PTSD and amnesia of the trauma, (c) no PTSD, or (d) control participants who simulated PTSD. Imagery was precipitated by presentation of an audiotape of a motor vehicle accident. Whereas the traumatic imagery of participants who had accurate recall of their trauma was consistent with third party accounts of the trauma, the imagery of amnesic participants was inconsistent with these accounts. Participants were then interviewed about cognitive and emotional aspects of their responses. All participants with PTSD and simulators reported similar levels of imagery detail, involuntariness, re-experiencing, and emotional response, and reported higher levels than participants with no PTSD. Findings are discussed in terms of cognitive and contextual factors that can mediate accurate and inaccurate traumatic imagery. © 1998 John Wiley & Sons, Ltd.
