The predominant relationship between sexual environment characteristics and HIV-serodiscordant condomless anal sex among HIV-positive men who have sex with men (MSM)

In some studies, situational factors have been shown to be stronger predictors of condomless sex than individual risk factors. Cross-sectional relationships between condomless anal sex (CAS) with HIV-serodiscordant partners and risk factors across ecological levels (individual, sexual environment) were examined using a sample (N = 60) of HIV-positive men who have sex with men (MSM) who reported multiple recent episodes of CAS. Negative binomial regressions were used to evaluate the association of contextual risk factors (e.g., substance use during sex, transactional sex, public sex, sex at a sex party) with recent condomless sex, controlling for demographics and mental health. Results demonstrated that sexual environment factors, particularly sex under the influence of drugs or alcohol (B = .019, p < .05), transactional sex (B = .035, p < .01), and public sex (B = .039, p < .01) explained a large proportion of the variance in CAS. Only sex at a sex party was not related to CAS (p = .39). For each additional sexual environment in which men engaged, their rates of CAS increased (B = .39, p < .01). Secondary prevention interventions that are tailored to the proximal sexual environment could be maximally effective, particularly if they address substance use and other challenging sexual situations.We are very grateful to the participants for their time and efforts in the study. Support for the current study came from a feasibility grant (PI: Conall O'Cleirigh) from the Harvard University Center for AIDS Research (Parent Grant: P30AI060354, PI: Bruce Walker, MD) awarded to Dr. Conall O'Cleirigh. Investigator support for Dr. Steven Safren also came from NIH Grant K24MH094214. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. (P30AI060354 - Harvard University Center for AIDS Research; K24MH094214 - NIH)Accepted manuscrip

Evaluating Consumer Response to GM Foods: Some Methodological Considerations

In 1998 the European Union placed a moratorium on the planting of transgenic crops within its borders. The resulting ban on biotech crops has led to the current trans-Atlantic trade dispute between the United States and the EU. At the heart of this dispute is the issue of consumer acceptance. The EU’s current position is predicated on perceived public concerns about biotech foods which found a voice in numerous opinion polls conducted during the late 1990s (e.g., European Commission, 1997, 2000). Such concerns have also been amplified by intense media coverage and resulting political activism. Given the pivotal role that consumer opinion has played in recent EU policy, an understanding of how consumers value biotech foods is critical to informed policymaking. To date three main approaches have been used to gauge how consumers might respond to genetically modified (GM) foods if they were labeled as such. Opinion or attitudinal surveys are one approach. Two other approaches that are also being used are choice experiments and experimental (auction) market methods. This paper provides a brief overview of each approach, their predictions regarding consumer willingness to pay(WTP) for biotech foods, and their potential advantages and pitfalls in predicting actual consumer behavior in the market place.Agricultural and Food Policy, Consumer/Household Economics, Research Methods/ Statistical Methods,

Monopolistic Competition with Two-Part Tariffs

Non-uniform pricing equilibria are shown to dominate uniform pricing equilibria in free entry, monopolistically competitive markets with identical consumers. The non-uniform pricing equilibrium is welfare optimal. Comparisons of Cournot and non-uniform pricing equilibria in terms of the equilibrium number of firms and sales per firm show that the positioning of Cournot equilibria relative to the welfare optimal configuration of firms and outputs depends on the relative curvatures of inverse demand and average cost functions, entry-induced rotation of inverse demand functions, and the relative price effects of changes in own and other firms outputs. The choice between the non-uniform and uniform pricing interpretations of equilibria in differentiated product markets may have important implications for policy analysis

Particle Astrophysics and Cosmology: Cosmic Laboratories for New Physics (Summary of the Snowmass 2001 P4 Working Group)

The past few years have seen dramatic breakthroughs and spectacular and puzzling discoveries in astrophysics and cosmology. In many cases, the new observations can only be explained with the introduction of new fundamental physics. Here we summarize some of these recent advances. We then describe several problem in astrophysics and cosmology, ripe for major advances, whose resolution will likely require new physics.Comment: 27 pages, 14 figure

Analyzing intramolecular vibrational energy redistribution via the overlap intensity-level velocity correlator

Numerous experimental and theoretical studies have established that intramolecular vibrational energy redistribution (IVR) in isolated molecules has a heirarchical tier structure. The tier structure implies strong correlations between the energy level motions of a quantum system and its intensity-weighted spectrum. A measure, which explicitly accounts for this correaltion, was first introduced by one of us as a sensitive probe of phase space localization. It correlates eigenlevel velocities with the overlap intensities between the eigenstates and some localized state of interest. A semiclassical theory for the correlation is developed for systems that are classically integrable and complements earlier work focusing exclusively on the chaotic case. Application to a model two dimensional effective spectroscopic Hamiltonian shows that the correlation measure can provide information about the terms in the molecular Hamiltonian which play an important role in an energy range of interest and the character of the dynamics. Moreover, the correlation function is capable of highlighting relevant phase space structures including the local resonance features associated with a specific bright state. In addition to being ideally suited for multidimensional systems with a large density of states, the measure can also be used to gain insights into the phase space transport and localization. It is argued that the overlap intensity-level velocity correlation function provides a novel way of studying vibrational energy redistribution in isolated molecules. The correlation function is ideally suited to analyzing the parametric spectra of molecules in external fields.Comment: 16 pages, 13 figures (low resolution

Ribosome Profiling Provides Evidence that Large Noncoding RNAs Do Not Encode Proteins

Large noncoding RNAs are emerging as an important component in cellular regulation. Considerable evidence indicates that these transcripts act directly as functional RNAs rather than through an encoded protein product. However, a recent study of ribosome occupancy reported that many large intergenic ncRNAs (lincRNAs) are bound by ribosomes, raising the possibility that they are translated into proteins. Here, we show that classical noncoding RNAs and 5′ UTRs show the same ribosome occupancy as lincRNAs, demonstrating that ribosome occupancy alone is not sufficient to classify transcripts as coding or noncoding. Instead, we define a metric based on the known property of translation whereby translating ribosomes are released upon encountering a bona fide stop codon. We show that this metric accurately discriminates between protein-coding transcripts and all classes of known noncoding transcripts, including lincRNAs. Taken together, these results argue that the large majority of lincRNAs do not function through encoded proteins