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A resource reservation protocol (RSVP), a flexible and scalable receiver-oriented simplex protocol, is described. RSVP provides receiver-initiated reservations to accommodate heterogeneity among receivers as well as dynamic membership changes; separates the filters from the reservation, thus allowing channel changing behavior; supports a dynamic and robust multipoint-to-multipoint communication model by taking a soft-state approach in maintaining resource reservations; and decouples the reservation and routing functions. A simple network configuration with five hosts connected by seven point-to-point links and three switches is presented to illustrate how RSVP works. Related work and unresolved issues are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Reducible transition metal oxides (RTMOs) comprise an important class of catalytic materials that are used for the selective oxidation and electro- and photochemical splitting of water, and as supports for metal nanoparticles. It is, therefore, highly desirable to model the properties of these materials accurately using density functional theory (DFT) in order to understand how oxide structure and performance are related and to guide the search for materials exhibiting superior performance. Unfortunately, accurate description of the structural and electronic properties of RTMOs using DFT has proven particularly challenging. The M06-L density functional, which has been shown to be broadly accurate for calculations of gas phase clusters, has recently become available to researchers carrying out calculations in the solid state, but its performance in determining the properties RTMOs has been little investigated. The aim of this work was to assess the performance of the M06-L functional for describing the structural and electronic properties of a family of RTMOs: MoO<sub>2</sub>, MoO<sub>3</sub>, and Bi<sub>2</sub>Mo<sub>3</sub>O<sub>12</sub>. Lattice constants, band gaps, and densities of states calculated using the M06-L functional are compared to those obtained from DFT+U. We have also used the M06-L functional to determine the reaction barrier for propene activation over Bi<sub>2</sub>Mo<sub>3</sub>O<sub>12</sub>, the rate-limiting step in the oxidation of propene to acrolein. We find that while DFT calculations carried out with the M06-L functional are roughly five times more expensive computationally than those performed with DFT+U, the results obtained using the M06-L functional provide sensible results for all properties investigated, while avoiding the necessary trade-off between accurate electronic structure and accurate thermochemistry that occurs in DFT+U.
Spatial extents of food webs that support stream and river consumers are largely unknown, but such information is essential for basic understanding and management of lotic ecosystems. We used predictable variation in algal δ13C with water velocity, and measurements of consumer δ13C and δ15N to examine carbon flow and trophic structure in food webs of the South Fork Eel River in Northern California. Analyses of δ13C showed that the most abundant macroinvertebrate groups (collector-gatherers and scrapers) relied on algae from local sources within their riffle or shallow pool habitats. In contrast, filter-feeding invertebrates in riffles relied in part on algal production derived from upstream shallow pools. Riffle invertebrate predators also relied in part on consumers of pool-derived algal carbon. One abundant taxon drifting from shallow pools and riffles (baetid mayflies) relied on algal production derived from the habitats from which they dispersed. The trophic linkage from pool algae to riffle invertebrate predators was thus mediated through either predation on pool herbivores dispersing into riffles, or on filter feeders. Algal production in shallow pool habitats dominated the resource base of vertebrate predators in all habitats at the end of the summer. We could not distinguish between the trophic roles of riffle algae and terrestrial detritus, but both carbon sources appeared to play minor roles for vertebrate consumers. In shallow pools, small vertebrates, including three-spined stickleback (Gasterosteus aculeatus), roach (Hesperoleucas symmetricus), and rough-skinned newts (Taricha granulosa), relied on invertebrate prey derived from local pool habitats. During the most productive summer period, growth of all size classes of steelhead and resident rainbow trout (Oncorhynchus mykiss) in all habitats (shallow pools, riffles, and deep unproductive pools) was largely derived from algal production in shallow pools. Preliminary data suggest that the strong role of shallow pool algae in riffle steelhead growth during summer periods was due to drift of pool invertebrates to riffles, rather than movement of riffle trout. Data for δ15N showed that resident rainbow trout (25–33 cm standard length) in deep pools preyed upon small size classes of juvenile steelhead that were most often found in riffles or shallow pools. While many invertebrate consumers relied primarily on algal production derived from local habitats, our study shows that growth of top predators in the river is strongly linked to food webs in adjacent habitats. These results suggest a key role for emigration of aquatic prey in determining carbon flow to top predators.
This paper is dedicated to the memory of Aaron, Spanish manchild and gym buddy, whom the ring could not save from the street. This paper benefited from the reactions, critical comments and encouragement of a number of colleagues, among whom Pierre Bourdieu, Rogers Brubaker, Dan Chambliss, Lynn S. Chancer, Rick Fantasia, Harvey Molotch, Bill Wilson, and members of the Center for European Sociology in Paris. My gratitude also goes to my colleagues in the "sweet science" who taught me much more than how to throw a left jab, and to the friends and family who supported me morally during this strenuous project (with special mention to Elizabeth Bonamour du Tartre for a major on-site assist). This research was made possible in part by the financial support of the Maison des sciences de l'homme, a Lavoisier Fellowship from the French governement, and the Milton Fund of Harvard University.
No abstract is provided for this article.
Insomnia, nightmares, or nocturnal panic attacks are prominent features of sleep disturbance that spans across many anxiery disorders. In a meta-analysis of 177 studies, Benca and colleagues (1992) reported that individuals with an anxiery disorder take longer ro get to sleep at the beginning of the night, experience more awakenings during rhe night, obtain less sleep overall, and exhibit poorer sleep efficienry, relative to nonpatients. More recently, a review of dre literature by Papadimitriou and Linkowski 2005) suggesrs rhat the major findings reported bv Benca et al. have held over the ensuing decade. \,foreover, Papadimitriou and Linkowski (2005) tbund an especially strong association beween sleep disturbance and several anxiety disorders, including panic disorder, generalized anxiery disorder (GAD), obsessive-compulsive disorder, and posttraumatic stress disorder (PTSD). Afthough -ort of the evidence to date is based on samples of aduhs in their rriddle years, there is also evidence ofan association )erween sleep disturbance and anxiety disorders in ;hildren and adolescence (Forbes et al., 2006), as well as among older adults (Spira, Friedman, Flint, & Sheikh,2005). The first aim of this chapter is to highlight the potential importance of sleep problems in individuals with anxiery disorders. W'e argue that disturbed sleep not only impairs the qualiry of a patientt life but may also contribute to rhe maintenance of the anxiety disorder. Our second aim is to review the evidence base for rrearing parienrs who sufFer from comorbid sleep disturbance and anxiery disorder. As will become evident throughout the chapter, there is a dearth of evidence that specifically delineates the relationship berween sleep disturbance and anxiery disorder and thus several ofour proposals are based on evidence from healthy nonpatients or patienrs with other clinical disorders. 'We raise this caveat at the outset as an importanr limitarion to rhe conclusions that we draw. 'We rurn now to begin this chapter by offering an overview of concepts that are basic to understanding human sleep; this knowledge is important for clinicians rreating individuals who sufFer from sleep disturbance. Sleep disturbances in the form of insomnia, nightmares, or nocrurnal panic attack are prominenr features across the anxiety disorders.The first aim ofthis chapter is to highlight rhe potential importance of sleep in individuals with anxiety disorders. lt is argued ttrat steep is important not only because disturbed sleep impairs the quality of a patient's life, but also because it likely contributes to the maintenance of the anxiety disorder. The second aim is to review the evidence base for treating Patients who suffer from comorbid insomnia and an anxiety disorder. Research attention and clinical intervention for sleep disturbance among individuals with anxiety disorders is a critical domain for future research.
The prototype willingness model (PWM) was designed to extend expectancy-value models of health behaviour by also including a heuristic, or social reactive pathway, to better explain health-risk behaviours in adolescents and young adults. The pathway includes prototype, i.e., images of a typical person who engages in a behaviour, and willingness to engage in behaviour. The current study describes a meta-analysis of predictive research using the PWM and explores the role of the heuristic pathway and intentions in predicting behaviour. Eighty-one studies met inclusion criteria. Overall, the PWM was supported and explained 20.5% of the variance in behaviour. Willingness explained 4.9% of the variance in behaviour over and above intention, although intention tended to be more strongly related to behaviour than was willingness. The strength of the PWM relationships tended to vary according to the behaviour being tested, with alcohol consumption being the behaviour best explained. Age was also an important moderator, and, as expected, PWM behaviour was best accounted for within adolescent samples. Results were heterogeneous even after moderators were taken into consideration. This meta-analysis provides support for the PWM and may be used to inform future interventions that can be tailored for at-risk populations.
