Exact Baryon, Strangeness and Charge Conservation in Hadronic Gas Models

Relativistic heavy ion collisions are studied assuming that particles can be described by a hadron gas in thermal and chemical equilibrium. The exact conservation of baryon number, strangeness and charge are explicitly taken into account. For heavy ions the effect arising from the neutron surplus becomes important and leads to a substantial increase in e.g. the $\pi^-/\pi^+$ ratio. A method is developed which is very well suited for the study of small systems.Comment: 5 pages, 5 Postscript figure

Fortress defense in social aphids

Dissertação de mestrado em Evolução e Biologia Humanas, apresentada ao Departamento de Ciências da Vida da Faculdade de Ciências e Tecnologia da Universidade de Coimbra.A idade à morte é um dos parâmetros a ser estimado pelo antropólogo forense, aquando da construção do perfil de um determinado indivíduo. O objectivo de tal análise é tentar estabelecer uma relação entre a idade cronológica e a idade biológica dos resquícios ósseos. São várias as metodologias utilizadas, sendo que a abordagem morfológica, se apresenta como mais recorrente, pois é, de certa forma, mais intuitiva. Contudo, os métodos microscópicos podem, em determinadas situações, revelar-se de extrema utilidade. A estimativa da idade em adultos baseia-se na observação da senescência intrínseca ao indivíduo. Este processo fisiológico tem bases celulares, logo não é de estranhar que a histologia tenha vindo a ser usada como ferramenta para aceder às microestruturas, que permitem estabelecer uma relação com a idade. O ponto fulcral deste projecto é testar a aplicabilidade da histomorfometria óssea na estimativa da idade, através do uso de metodologias práticas e de fácil execução. Esta investigação pretende, com base numa amostra forense de clavículas provenientes de 18 indivíduos, 10 do sexo feminino e 8 do sexo masculino, estabelecer uma relação entre a idade à morte e dois componentes histológicos, a percentagem de osso não remodelado e aérea cortical relativa. Os resultados obtidos foram altamente condicionados pelo número da amostra tendo um carácter preliminar. Não foi possível estabelecer uma relação entre a percentagem de osso não remodelado e a idade, devido a um conjunto de situações condicionantes. Em relação à área cortical relativa, foi possível observar que esta exibe uma tendência para diminuir em indivíduos mais velhos, já que segundo os resultados obtidos, as principais diferenças encontram-se nos dois extremos etários. Os indivíduos mais jovens apresentam uma área cortical relativa superior (63,66%) quando comparados aos indivíduos mais velhos (57,96%). Esta variável parece ser ainda influenciada pelo sexo, chegando mesmo a existir, no grupo etário dos 40 aos 49 anos, uma diferença de aproximadamente 16%. Sempre que possível, os resultados obtidos, ou a falta destes, foram analisados criticamente, sendo que o condicionamento da amostra revelou-se um grande impedimento ao presente estudo. Um balanço geral da metodologia usada, quer ao nível da preparação para a histologia, quer na análise microscópica e com recurso ao scâner. Esta última revelou-se de mais fácil aplicação, embora careça de resultados mais fidedignos. O desenvolvimento de investigações, que visem a aplicação da histologia na estimativa da idade, é um processo premente e basilar, dado existirem empiricamente menos estudos na área, comparativamente aos métodos morfológicos. Deste modo, pensa-se que apesar dos resultados obtidos, novos projectos poderão ser alcançados, com base na temática em estudo.Age at death is one of the key objectives that need to be estimated by the forensic anthropologist, when building the profile of an individual. The aim of this analysis is to establish a relationship between chronological age and the age observed in human skeletal remains. Several methods are used for this purpose, and the morphological approach seems to be the most recurrent, because somehow it is more intuitive. However, the microscopic methods can, under certain circumstances, be extremely useful. The age estimation in adults is based on the observation of the natural senescence, inherent to the individual. This physiological process has a cellular basis, so it is not unpredictable that histology has been used as a tool to access these microstructures, which ultimately may de related with age. The main goal of this project is to test the applicability of bone histomorphometry in the estimation of age at death, through the use of methods that are, at its core, practical and easy to perform. The current investigation is based on forensic samples of clavicles from 18 individuals (10 females and 8 males). It was intended to establish a relationship between age at death and two histological components, the percentage of unremodeled bone and the relative cortical area. The results were highly conditioned by the sample. Therefore emphasis is placed in the preliminary character of those. It was not possible to establish an association between the percentage of unremodeled bone and age at death, due to a set of circumstances that restricted all the analysis. Regarding the analysis of the cortical relative area, it was possible to verify that this component presents a downward trend in older individuals, since the main differences were found in extreme ages. Thereby younger individuals present a higher value of cortical area (63,66%) when compared with older individuals (57,96%). This variable seems to be sexrelated, since in the age group of 40 to 49 years, it was possible to verify about 16% of difference between sexes. Whenever possible, all the results, or the lack of them, were critically analyzed. It is important to state that the sample size was a major drawback to this study. Nevertheless it was still possible to come up with some hypotheses that may in theory explain the results. A general deliberation of the methodology used was performed both in terms of the preparation for histology as well as towards the analysis of the microstructures per se. The examination that used the scanner proved to be easier to implement, although it lacks of reliable results. The development of investigations concerning the application of histology in age at death estimation is an urgent and fundamental process, since there are empirically fewer studies in the area when compared to macroscopic approach. Thus, in spite of the results we think that a path was opened to the enlargement of future studies that use histology as a tool for age estimation in a Portuguese sample

First upper limit analysis and results from LIGO science data: stochastic background

I describe analysis of correlations in the outputs of the three LIGO interferometers from LIGO's first science run, held over 17 days in August and September of 2002, and the resulting upper limit set on a stochastic background of gravitational waves. By searching for cross-correlations between the LIGO detectors in Livingston, LA and Hanford, WA, we are able to set a 90% confidence level upper limit of h_{100}^2 Omega_0 < 23 +/- 4.6.Comment: 7 pages; 1 eps figures; proceeding from 2003 Edoardo Amaldi Meeting on Gravitational Wave

Astrometric observations of Saturn's satellites from McDonald Observatory, 1972

Observations of Saturn's satellites were reduced by means of secondary reference stars obtained by reduction of Palomar Sky Survey (PSS) plates. This involved the use of 39 SAO stars and plate overlap technique to determine the coordinates of 59 fainter stars in the satellite field. Fourteen plate constants were determined for each of the two PSS plates. Comparison of two plate measurement and reduction techniques on the satellite measurements demonstrate the existence of a serious background gradient effect and the utility of microdensitometry to eliminate this error source in positional determinations of close satellites

Naming is Power: Citation Practices in SoTL

Citing is a political act. It is a practice that can work both sides of the same coin: it can give voice, and it can silence. Through this research, we call for those contributing to the scholarship of teaching and learning (SoTL) to attend to this duality explicitly and intentionally. In this multidisciplinary field, SoTL knowledge-producers bring the citation norms of their home disciplines, a habit that calls for interrogation and negotiation of the citation practices used in this shared space. The aim of our study was to gather data about how citation is practiced within the SoTL community: who we cite, how we cite, and what values, priorities, and politics are conveyed in these practices. We were also interested in whether any self-selected categories of identity (e.g., gender, career stage) related to self-described citation practices and priorities. Findings suggest several statistically significant relationships did emerge, which we identify as important avenues for further research and writing. We conclude with 10 principles of citation practices in SoTL.

Ocean Dynamics and the Inner Edge of the Habitable Zone for Tidally Locked Terrestrial Planets

Recent studies have shown that ocean dynamics can have a significant warming effect on the permanent night sides of 1 to 1 tidally locked terrestrial exoplanets with Earth-like atmospheres and oceans in the middle of the habitable zone. However, the impact of ocean dynamics on the habitable zone's boundaries (inner edge and outer edge) is still unknown and represents a major gap in our understanding of this type of planets. Here we use a coupled atmosphere-ocean global climate model to show that planetary heat transport from the day to night side is dominated by the ocean at lower stellar fluxes and by the atmosphere near the inner edge of the habitable zone. This decrease in oceanic heat transport (OHT) at high stellar fluxes is mainly due to weakening of surface wind stress and a decrease in surface shortwave energy deposition. We further show that ocean dynamics have almost no effect on the observational thermal phase curves of planets near the inner edge of the habitable zone. For planets in the habitable zone's middle range, ocean dynamics moves the hottest spot on the surface eastward from the substellar point. These results suggest that future studies of the inner edge may devote computational resources to atmosphere-only processes such as clouds and radiation. For studies of the middle range and outer edge of the habitable zone, however, fully coupled ocean-atmosphere modeling will be necessary. Note that due to computational resource limitations, only one rotation period (60 Earth days) has been systematically examined in this study; future work varying rotation period as well as other parameters such as atmospheric mass and composition is required.Comment: 34 pages, 13 figures, and 1 tabl