A point mass in an isotropic universe: III. The region R≤2mR\leq 2m

McVittie's solution of Einstein's field equations, representing a point mass embedded into an isotropic universe, possesses a scalar curvature singularity at proper radius $R=2m$. The singularity is space-like and precedes, in the expanding case, all other events in the space-time. It is shown here that this singularity is gravitationally weak, and the possible structure of the region $R\leq 2m$ is investigated. A characterization of this solution which does not involve asymptotics is given.Comment: Revtex, 11pp. To appear in Class.Quant.Grav. Paper II appeared as Class. Quant. Grav. 16 (1999) 122

Expansion-induced contribution to the precession of binary orbits

We point out the existence of new effects of global spacetime expansion on local binary systems. In addition to a possible change of orbital size, there is a contribution to the precession of elliptic orbits, to be added to the well-known general relativistic effect in static spacetimes, and the eccentricity can change. Our model calculations are done using geodesics in a McVittie metric, representing a localized system in an asymptotically Robertson-Walker spacetime; we give a few numerical estimates for that case, and indicate ways in which the model should be improved.Comment: revtex, 7 pages, no figures; revised for publication in Classical and Quantum Gravity, with minor changes in response to referees' comment

Spectral determinations for discrete sources with EGRET

The ability of the EGRET (Energetic Gamma-Ray Experimental Telescope) to determine the spectral parameters of point sources in 14-day exposures, as planned for the initial survey phase of the GRO (Gamma Ray Observatory) mission, is explored by numerical simulation. Results are given for both galactic and extragalactic objects as a function of source strength and for representative levels of diffuse background emission

Analysis of the Evolutaion of Scope Management and Needs Identification in Agile Methodologies

Identifying stakeholders, identifying metrics, and analyzing specific aspects of agile development. This has led to a variety of questions around scope management such as How do scope changes impact the velocity throughout the course of a project? , What factors help determine the overall viability of adopting different scope measures? , and What are the roles of project owners and managers in facilitating scope changes in project cycles? This research encompasses a review of previous literature, an analysis of structured project progression, and semi-structured interviews in order to investigate the evolution of scope management and needs identification in agile methodologies

All Maximally Entangled Four Qubits States

We find an operational interpretation for the 4-tangle as a type of residual entanglement, somewhat similar to the interpretation of the 3-tangle. Using this remarkable interpretation, we are able to find the class of maximally entangled four-qubits states which is characterized by four real parameters. The states in the class are maximally entangled in the sense that their average bipartite entanglement with respect to all possible bi-partite cuts is maximal. We show that while all the states in the class maximize the average tangle, there are only few states in the class that maximize the average Tsillas or Renyi $\alpha$-entropy of entanglement. Quite remarkably, we find that up to local unitaries, there exists two unique states, one maximizing the average $\alpha$-Tsallis entropy of entanglement for all $\alpha\geq 2$, while the other maximizing it for all $0<\alpha\leq 2$ (including the von-Neumann case of $\alpha=1$). Furthermore, among the maximally entangled four qubits states, there are only 3 maximally entangled states that have the property that for 2, out of the 3 bipartite cuts consisting of 2-qubits verses 2-qubits, the entanglement is 2 ebits and for the remaining bipartite cut the entanglement between the two groups of two qubits is 1ebit. The unique 3 maximally entangled states are the 3 cluster states that are related by a swap operator. We also show that the cluster states are the only states (up to local unitaries) that maximize the average $\alpha$-Renyi entropy of entanglement for all $\alpha\geq 2$.Comment: 15 pages, 2 figures, Revised Version: many references added, an appendix added with a statement of the Kempf-Ness theore

A review of the immunomodulating components of maternal breast milk and protection against necrotizing enterocolitis

Breast milk contains immunomodulating components that are beneficial to newborns during maturation of their immune system. Human breast milk composition is influenced by an infant\u27s gestational and chronological age, lactation stage, and the mother and infant\u27s health status. Major immunologic components in human milk, such as secretory immunoglobulin A (IgA) and growth factors, have a known role in regulating gut barrier integrity and microbial colonization, which therefore protect against the development of a life-threatening gastrointestinal illness affecting newborn infants called necrotizing enterocolitis (NEC). Breast milk is a known protective factor in the prevention of NEC when compared with feeding with commercial formula. Breast milk supplements infants with human milk oligosaccharides, leukocytes, cytokines, nitric oxide, and growth factors that attenuate inflammatory responses and provide immunological defenses to reduce the incidence of NEC. This article aims to review the variety of immunomodulating components in breast milk that protect the infant from the development of NEC

Condom Use among Young African American Men: Implications for Planning Interventions

Condom Use among Young African American Men: Implications for Planning Interventions Sexually transmitted diseases, including HIV, continue to present significant public health problems affecting young people in the United States, especially African Americans. While African Americans make up about 12% of the U.S. population, in 2010 they accounted for 44% of new HIV infections in 2010 and 48% of all persons living with AIDS in 2007. The 2010 data shows that of these new cases, 38% occurred among African American males ages 13-24 years old. Correct condom use remains a challenge in this population and efforts to increase condom use among minority males has been a formidable challenge. This paper reports the results of formative research conducted in order to guide the development of an intervention to increase consistent, effective condom use for young African American males. Methods: A snowball sampling approach was used to recruit participants. African American males, ages 18-24, who self-reported as sexually active were eligible to participate in one of four focus groups or one of six individual interviews. All study events were conducted at community locations. Each event was audiotaped and notes were taken. Analysis was performed using using NVivo-9. The coding strategy included emic and etic codes and a coding tree was developed which was used to identify themes. Results: A total of 36 African American males between the ages of 18-24 (mean 20.7 years) took part. In general, participants felt condom use was highly influenced by contextual factors including partner interest, partner communication, length of relationship and trust. Condom use was also influenced by a sense of invincibility and being caught up in the moment. Notably, most sexual activity occurred outside of a relationship, most often within the party scene or as quickly arranged hook-ups. Analysis: In order to ensure maximum impact on the development of the intervention, the results from this formative phase were viewed through the Transtheoretical Model of Behavior Change (TTM) and most participants would be described as being in the pre-contemplation or contemplation stages of behavioral change. While all participants expressed some understanding of the risks of unprotected sex, many did not connect risks to consequences. While the data did not indicate that condom use behavior was likely to change in the short-term (less than 6 months), several participants were contemplating making a change. Discussion: The snowball sampling approach allowed us to understand the participants’ social network and allowed us to consider social influences as well as about individual attitudes and beliefs. In the TTM frame, interventions designed for this population need to include contemplators and pre-contemplators and should focus on modification of cognition, affect and behaviors. Our research also shows that several of the underlying assumptions of TTM are at odds with the framework within which sex often occurs for this population and condom use decisions are highly influenced by the social context. In light of the results, the intervention placed condom use into a health promotion context. It combines group activities and one-on-one interaction. Group activities can impact shared values and beliefs and, thus, the intervention builds social support for behavior changes while addressing individual capacity