Palatini inflation in models with an R2R^2 term

The Starobinsky model, considered in the framework of the Palatini formalism, in contrast to the metric formulation, does not provide us with a model for inflation, due to the absence of a propagating scalar degree of freedom that can play the role of the inflaton. In the present article we study the Palatini formulation of the Starobinsky model coupled, in general nonminimally, to scalar fields and analyze its inflationary behavior. We consider scalars, minimally or nonminimally coupled to the Starobinsky model, such as a quadratic model, the induced gravity model or the standard Higgs-like inflation model and analyze the corresponding modifications favorable to inflation. In addition we examine the case of a classically scale-invariant model driven by the Coleman-Weinberg mechanism. In the slow-roll approximation, we analyze the inflationary predictions of these models and compare them to the latest constraints from the Planck collaboration. In all cases, we find that the effect of the $R^2$ term is to lower the value of the tensor-to-scalar ratio.Comment: 22 pages, 8 figures, JCAP accepted versio

Rescuing Quartic and Natural Inflation in the Palatini Formalism

When considered in the Palatini formalism, the Starobinsky model does not provide us with a mechanism for inflation due to the absence of a propagating scalar degree of freedom. By (non)--minimally coupling scalar fields to the Starobinsky model in the Palatini formalism we can in principle describe the inflationary epoch. In this article, we focus on the minimally coupled quartic and natural inflation models. Both theories are excluded in their simplest realization since they predict values for the inflationary observables that are outside the limits set by the Planck data. However, with the addition of the $R^2$ term and the use of the Palatini formalism, we show that these models can be rendered viable.Comment: JCAP accepted version, 16 pages, 7 figure

Dealers' incentives to reveal their names

This research investigates dealers' motivation to disclose their names when quoting on the NASDAQ over the years. NASDAQ enables dealers to quote limit orders either anonymously or with a feature that reveals their names. Results are consistent with dealers advertising by revealing their identities so as to develop and maintain their reputation for reliable pricing. Dealers strategically choose to reveal their identities when order flow is profitable. Post‐name disclosure analysis further suggests that named quotations are likely to be driven by informational considerations. This research contributes to our understanding of the use of non‐anonymity in electronic trading

Psychosocial Adjustment in Children of Immigrants

For immigrants, assimilation into mainstream society is complex, with numerous layers and experiences across multiple settings (e.g., employment, education, healthcare). In addition, immigrant populations are underserved and under-resourced compared to native populations, with major systemic barriers that influence socioeconomic status as well as immigrant ability to maximize education and employment potential. In turn, these difficulties have an adverse impact on psychosocial wellbeing in immigrants broadly. Immigrant youth are a particularly vulnerable population facing an even more complex set of barriers and challenges in addition to the typical challenges associated with identity development in adolescence. However, multiple factors have been explored as predictors of their psychosocial wellbeing for immigrant youth. These have included socioeconomic status, educational achievement, discrimination at school, acculturation orientation (English language development, familism), and relationships (family cohesion and close friendships). This study was interested in exploring the influence of these variables on feelings of sadness and depression in immigrant youth. In order to explore these variables, the Children of Immigrants longitudinal study (CILS; Portes & Rumbaut, 1991-2006) was used. The CILS data set offered the ability to explore the experiences of immigrant youths at two time periods (Time 1 in 1992 and Time 2 in 1995). It was hypothesized that the Time 1 predictors (socioeconomic status, educational aspiration versus perceived achievement ability, discrimination, primary language, parent/respondent acculturation discrepancy, parent/ respondent clash frequency, and number of close friendships) would predict feelings of sadness and depression at both Time 1 and Time 2. Secondly, it was hypothesized that the Time 2 predictors (educational aspiration versus perceived achievement ability, discrimination, parent/respondent acculturation discrepancy, parent/respondent clash frequency) would predict feelings of sadness and depression at Time 2. Regression results showed that the key factors which influenced youth immigrant’s reports of sadness and depression at times 1 and 2, include the immigrant’s experiences of discrimination, educational aspirations versus achievement, parent/child clash frequency, and number of close friendships. While working with this particularly vulnerable group, it is important for providers (educators, social workers, mental health providers, and medical providers) to be aware of key factors

Study of the medical-social aspects of gonorrhea in sixty-five male patients under twenty-six years of age admitted to the genito-urinary clinic of the Boston City Hospital, from October 1, 1937 to March 30, 1938

Thesis (M.S.)--Boston University, 1938. This item was digitized by the Internet Archive

Hop, The Heat Shock Link between Hsp90 and the Piwi-piRNA Pathway

The Piwi-piRNA pathway is an RNA interference pathway that is conserved across eukaryotes; it is involved with the maintenance of genomic stability through its actions on the germline. We have studied the relationship between a protein complex involving factors in the Piwi-piRNA pathway, Piwi and Aubergine, and the Hsp90-Hop-Hsp70 molecular chaperone machinery. Through a series of in vitro experiments and previous data, we have shown that an interaction between Piwi, Hop, and Hsp90 occurs, when all three proteins are present. Shedding light on this interaction could give us insight on how the PiwipiRNA pathway functions. Through in vivo experiments performed, we have shown that germline knockdowns of Hop, Hsc70-4, and Hsp83 have impacts on the Piwi-piRNA pathway’s ability to perform its function suppressing transposable elements. Through deep sequencing of the total small RNA population present under a Hop germline knockdown, as well as analysis of the population of piRNAs bound to Piwi when Hop is knocked down, we have shown the first evidence of molecular chaperone involvement in both the biogenesis and the loading of piRNAs onto Piwi. This work will help to elucidate the function of the Piwi-piRNA pathway in Drosophila melanogaster. We aim to continue this work by performing deep sequencing experiments on the Hsc70-4 and Hsp83 germline knockdown samples to fully assess their impacts on the loading and biogenesis of piRNAs

Use of Contingent Valuation Analysis in a Developing Country: Market Perceptions of Contamination on Johannesburg’s Mine Dumps

This study reports the results of a contingent valuation (CV) survey that was carried out in Johannesburg, South Africa. Students at Wits University conducted more than 300 face-to-face interviews with Africans living and/or working in Soweto, an African township located on the outskirts of Johannesburg, and nearby areas. The questions they asked were designed to determine the perceptions of risk regarding airborne mine dust and radon, a naturally occurring gas, and the effect that these perceptions had on the valuation of residential properties impacted by these substances. A probit model was used to evaluate the determinants of bidder behavior, using respondent demographics and other characteristics as independent variables. Residential property discounts for potentially contaminated housing sites by marginal bidders at the top of the market varied from -24% to -50%. Research issues in developing countries were addressed. Contingent valuation results in South Africa were compared to published results in the United States.