Galaxy formation by dust

It has been known since the early 1940's that radiation can cause an instability in the interstellar medium. Absorbing dust particles in an isotropic radiation field shadow each other by a solid angle which is inversely proportional to the square of the distance between the two particles, leading to an inverse-square attractive force - mock gravity. The effect is largest in an optically thin medium. Recently Hogan and White (HW, hereafter) proposed that if the pre-galactic universe contained suitable sources of radiation and dust, instability in the dust distribution caused by mock gravity may have led to the formation of galaxies and galaxy clusters. In their picture of a well-coupled dust-gas medium, HW show that mock gravity begins to dominate gravitational instability when the perturbation becomes optically thin, provided that the radiation field at the time is strong enough. The recent rocket observation of the microwave background at submillimeter wavelengths by Matsumoto et al. might be from pre-galactic stars, the consequence of the absorption of ultraviolet radiation by dust, and infrared reemission which is subsequently redshifted. HW's analysis omits radiative drag, incomplete collisional coupling of gas and dust, finite dust albedo, and finite matter pressure. These effects could be important. In a preliminary calculation including them, the authors have confirmed that mock gravitational instability is effective if there is a strong ultraviolet radiation at the time, but any galaxies that form would be substantially enriched in heavy elements because the contraction of the dust is more rapid than that of the gas. Moreover, since the dust moves with supersonic velocity through the gas soon after the perturbation becomes optically thin, the sputtering of dust particles by gas is significant, so the dust could disappear before the instability develops significantly. They conclude that the mock gravity by dust is not important in galaxy formations

Make Inlet Piping and PSV One-System

PresentationFor pressure safety valves and associated inlet piping, the API recommends the non-recoverable pressure loss should not exceed 3 % of the set pressure at rated capacity flow, with some exceptions, e.g., for remote sensing pilot operated pressure safety valves. The API further notes pressure losses above 3 % are allowable if an engineering analysis shows valve performance is not impacted during relief. The API provides little guidance on the recommended engineering analysis. Calculations show the inlet piping and pressure safety valve (PSV) should be considered one system. Analysis of the system improves the basis for judging pressure safety valve performance, especially when compared with treating inlet piping separately from the PSV and then somewhat arbitrarily judging performance adequacy. With increasing inlet piping pressure loss, the energy in the velocity head at the inlet to the PSV grows in significance. Analyzing the inlet piping pressure loss separate from the PSV neglects this energy and makes the experience and knowledge of the judging engineer paramount. Given current computational capability and today’s litigious regulatory environment, an analytical and consistent basis for judging PSV performance may be of interest

Changes in the nature and governance of public spaces in the historic city centre : the case of Damascus

Public space is a component of our physical environment which has an important role in city life. This thesis is primarily about investigating public space and public realm in the historic city centre of Damascus in order to understand the potential for its improvement, and secondarily about recommending specific actions towards this. The research takes a qualitative approach focusing on public space as a ‘product’ which is the result of a process. In terms of the product, the nature, morphological and functional aspects of public spaces in Damascus are examined. The governance process is analysed at local level to define main actors, the rules they interact with and the rationalities they use to intervene in public space. This analysis includes locality-specific literature review and interviews with key informants. Such case study analysis is undertaken against the background of a survey of public space regeneration in selected cities around the Mediterranean. Public spaces in Damascus historically developed under strong endogenous social and cultural rules creating a hierarchy of ‘traditional’ spaces which supported public, parochial and private realms. In the contemporary period, these spaces have gone through modernisation in their governance process through introducing new actors and more formal rules, which have led to more ‘publicness’ and tension between tradition and modernisation. This has affected their nature as well as morphological and functional aspects. Analysis showed that strong centralised political and public sector control is found over the governance process through a top-down representative approach. Capacities, interests and perception of public spaces among actors, in addition to poor management, strict legislation and lack of qualified cadres, have all contributed to the continuing deteriorating situation of public spaces. Moreover, interventions for improvement occurred on a short-term basis and mainly to restore historical monuments and improve traffic. An integrated approach to upgrading open spaces is still needed on a long term basis, subject to the available financial resources, with wider governance arrangements and further collaboration and integration between different governmental bodies

Reading on Grade Level in Third Grade: How Is It Related to High School Performance and College Enrollment?

Illustrates how third-grade reading level correlates with eighth-grade reading level, which, along with ninth-grade school traits, correlates with ninth-grade performance, which in turn correlates with high school graduation and college attendance rates

After-School Programs and Academic Impact: A Study of Chicago's After School Matters

What impact can after-school programs have on the educational achievement of high school students? A new study of Chicago's After School Matters (ASM) program -- which offers paid internships in the arts, technology, sports, and communications to teenagers in some of the city's most underserved schools -- finds a relationship between participating in after-school activities and higher class attendance, lower course failures and higher graduation rates.Even after taking into account student demographic characteristics and prior attendance records, students who participate in ASM miss fewer days of school than their classmates. Similarly, students who participated at the highest levels in the after-school program tended to fail fewer core academic courses (English, Math, Science, and Social Studies). Furthermore, over the course of their time in high school, students who were enrolled in ASM for three or more semesters and those who participated at the highest levels had higher rates of graduation and lower dropout rates than similar students who did not participate in the program.The findings in this report highlight the importance of further research into what leads students to participate in after-school programs and the factors that lead to higher engagement and retention once they are enrolled. A better understanding is crucial for improving enrollment in after-school programs such as ASM. Moreover, accounting for student factors that lead to a greater engagement in the program will lead to a clearer understanding of ASM's contribution to the positive outcomes -- independent of hard-to-observe student characteristics such as enthusiasm or dedication

ELECTROMAGNETIC FIELD SIGNATURES IN THE OPTICAL SPECTRUM

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72857/1/j.1749-6632.1966.tb50958.x.pd

The “Emotionally Relevant” Congregation

The case for emotional relevance is more easily made than for cultural relevance. Simply stated, the emotional lives of a great many pre-Christian people (and many Christian people) are dysfunctional, out of control, and crippling their lives. We meet people (and families) every day whose lives are hijacked by powerful emotions they do not understand, and may even deny