Thesis (Ph.D.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / Recent experimental work has indicated that the thymus in late fetal and early neonatal life plays a major role in the development of mechanisms of immunity. To date, however, no study of the ultrastructure of the prenatal thymus has been reported in the literature, and histochemical and cytochemical studies of this early period are fragmentary. Therefore, in an effort to extend present knowledge of thymic differentiation and function during its early development, the thymus in the golden hamster (Mesocricetus auratus) was studied by selected histochemical methods and by electron microscopy from 9 1/2 days post coitum through 24 hours post partum. Histochemical techniques for the light microscopy included the periodic acid-Schiff technique with salivary digestion control for glycogen, the methyl green-pyronin technique as an indicator for protein synthesis, the sudan black B technique for determination of total unbound lipid, the Nile blue and oil r ed 0 techniques for deter mination of neutral lipid, and the Elftman t echnique for determination of phospholipid. Material was prepared for electron microscopy by fixation for one hour in l% osmium tetroxide (Millonig, 1963), dehydration in graded acetones followed by propylene oxide, and embedding in Maraglas epoxy resin (Freeman and Spurlock, 1962). Grids prepared from these specimens were stained either with 1% phosphotungstic acid in 95% alcohol, or with lead citrate (Reynolds, 1963). They were scanned with either an R.C.A. EMU 2-B electron microscope or a Siemens Elmiskop I. [TRUNCATED] / 2031-01-01

Submitted by Erika Demachki (erikademachki@gmail.com) on 2014-08-28T17:35:15Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) TCC_modelo_latex.pdf: 3051582 bytes, checksum: b61116ac48cf2249250d70dbc256ecc6 (MD5) / Made available in DSpace on 2014-08-28T17:35:15Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) TCC_modelo_latex.pdf: 3051582 bytes, checksum: b61116ac48cf2249250d70dbc256ecc6 (MD5) Previous issue date: 2014-03-01 / It is shown, in this work, a study about the golden number, represented by the greek character (pronounced as \Fi"), in tribute to the greek sculptor F dias, who used to use this number in his works. It is done an algebraic approach, which is shown how to reach the number , using reasons, proportions and equations of second grade. It is also used geometric constructions for its achievement. The used metodology is made of theory and practice, proposing activities where the concret assists the instruction of abstract geometry, in the construction, for example, of the golden rectangle and the logarithmic spiral. It is also shown the intrinsic relationship of the golden number and the Fibonacci sequence and, as well, it is shown that is an irrational and algebric number. The main goal is to promote the thinking of the importance of this number through a project to be developed at the same time as the classes, for students of secondary schools. / Apresenta-se, neste trabalho, um estudo relacionado ao número de ouro, representado pela letra grega Fi (lê-se: "Fi"), em homenagem ao escultor grego F dias, que fazia uso desse número em suas obras. E feita uma abordagem algébrica, onde e mostrado como chegar ao número , com o uso de razões, proporções e equações do 2o grau. Faz-se, também, uso de construções geométricas para a sua obtenção. A metodologia empregada e de natureza te orica e pr atica, propondo-se atividades onde o concreto auxilia o ensino da geometria abstrata na construção, por exemplo, do retângulo áureo e da espiral logar tmica. E mostrada, tamb em, a rela c~ao intr nseca que h a entre o n umero de ouro e a sequência de Fibonacci e, ainda, é demonstrado que Fi é um número irracional e algébrico. O objetivo principal e promover a reflexão da importância desse número através de um projeto a ser desenvolvido paralelamente as aulas, para alunos do ensino médio.

Treatise (D.M.A.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

This study examines the factors that influence the seasonal movements of Golden Eagles (Aquila chrysaetos), and can thus provide important information that helps to improve the protection of the species. There were two main purposes of this study. First, I wanted to analyze the difference between preferences of juvenile and adult Golden Eagles in their choice of southern or northern hibernation areas. Do younger eagles prefer moving longer distance to southern areas of Sweden? Second, I wanted to investigate how the climate influenced the choice of date of migration in the fall. In other words, does an early winter arrival influence the migration date of Golden Eagles? I also investigated if food availability influenced the migration date in combination with winter arrival? For the statistical analyses, 14 years (1998-2011) of data on snow conditions, temperatures, food availability and records on banded eagles from the counties Ångermanland and Västerbotten were used. I found that young eagles preferred to move further south, while adults tended to move much shorter distances or remained in the nesting area during the winter. How early or late in the fall the eagles moved was mainly affected by the first day when the temperature was -10°C or below combined with the first day when the snow depth reached at least 8 cm. Another factor that seemed to affect the date of migration was the amount of food (smaller prey), which influenced the effects of temperature and snow cover. For example, there were instances when good food availability led to eagles deciding to stay longer despite early snowfall. This important knowledge on how climatic factors and food availability influence the migration of Golden eagles can be useful when developing conservation programs for their future protection.

In this thesis, we design a robust concatenated code for the Multiple-Input Multiple-Output (MIMO) system in the presence of slow Rayleigh fading with no channel side information at the transmitter (no CSIT) and perfect channel side information at the receiver (perfect CSIR). Since we are interested in the slow fading channel, outage capacity is used as the measure of performance. Good space-time codes can be designed so as to maximize the so-called rank and the determinant criteria. However, a practical system will concatenate a space-time code with an outer code at the transmitter and perform iterative decoding at the receiver. It is necessary to design the space-time code together with the outer code in practice. We will call this kind of code a concatenated space-time code. At the transmitter, we will consider the bit-to-symbol mapping and space-time code together as a space-time modulator and thus, Bit Interleaved Coded Modulation (BICM) and Multilevel coding (ML) can be applied to design outer codes for the nonbinary constellation. However, the concatenated space-time codes designed by these two methods can only be decoded with arbitrarily small error probability for a fixed channel realization and such designs are not robust over the ensemble of fading channels. Our approach of designing concatenated space-time code is to design an outer code for a space-time modulator such that the concatenated space-time code can be decoded with arbitrarily small error probability in a set of fixed channels which have the same capacity. Through this approach, we discovered a new design criterion for spacetime codes: a good space-time code should stabilize its Extrinsic Information Transfer (EXIT) charts. In other words, the robustness of a space-time code in the slow fading channel and its performance in iterative decoding can be visualized by the EXIT charts. The rank and the determinant criterion do not evaluate the performance of a space-time code in iterative decoding, but the new criterion does. Therefore, the new criterion is applicable to design concatenated space-time codes. Applying our approach and new criterion, a rate 7.2 bits/s/Hz concatenated space-time code is designed. The performance is close to the outage capacity, and the rate lost is 0.2 bits/s/Hz.

Understanding species-habitat relationships is fundamental to the conservation of a species. This is especially important when the species is considered endangered. The Golden-cheeked Warbler is a habitat specialist that breeds only in oak-juniper woodlands (considered a climax forest) of central Texas. The warbler was listed as endangered under the federal Endangered Species Act primarily because of habitat loss and fragmentation. Conservation measures include the preservation of existing habitat and attempts to manage and enhance areas that once supported the warbler to return to the climax oak-juniper woodlands. My objectives were (1) to quantify the vegetation structure and species composition by vegetation volume of occupied warbler habitat across the breeding range in Texas and (2) to quantify the habitat use by the warbler in categories of behavior, substrate, height, and tree species. Instantaneous, focal animal behavioral observations were collected for three breeding seasons at six sites across the range of the warbler. Warbler behavior and microhabitat use were compared to availability of vegetation volume by height class and tree species. I found that Goldencheeked Warbler habitat varied by vegetation volume, canopy height and tree species among all sites. The warbler preferred twigs and foliage and the upper two height classes of the habitat structure for all behaviors. Tree species use did not match availability at any sites. The one consistent species result was the warbler used Ashe juniper significantly less than it occurred at all sites. Other major species were used disproportionately to the species occurrence at each site. Some tree species were used more often than they occur in the habitat while others species were used less than they occur in the habitat. Preferences for height class and tree species use were not significantly influenced by vegetation volume. Some other factor not measured such as prey availability may be the cause. Because warbler habitat characteristics and use vary across the range, any efforts to manipulate vegetation to become habitat must consider regional characteristics of Golden-cheeked warbler habitat.

Zugl.: Leipzig, Univ., Diss., 2009

The attributes of landscapes, abiotic and biotic, influence the behaviour of animals. Understanding the reciprocal effects between the landscape, habitats and the animals are an essential tool in sustainable management of natural resources as well as conservation. A source of information about how the environment shapes the behaviour of animals is movement data. The advent of cheap GPS devices has facilitated data collection. The fine scale spatio-temporal resolution allows the identification of complete home-ranges, even habitat that is only transiently used. Fine-scale movement data can also be used as proxy for behaviour-types; different behaviour states cause different movement tracks. I test, extend and apply the multi-change point analysis (MCPA), developed by Gurarie et al. (2009) for the identification of behavioural change points in irregular movement data. The method relies on conventional time-series analysis methods, rather than a Bayesian framework, such as the state space models. After thorough testing of the MCPA, we apply the method and its extension to the GPS data of four red deer and 27 golden eagles. The red deer data were analysed to detect behavioural changes at a seasonal scale and to serve as a test-bed for our extension of the MCPA. The comparison of movement bouts revealed that the expression of behaviour was on a gradient rather than the discreet states. The study of the golden eagle data highlighted the necessity to choose the appropriate sampling regime of movement. If the intervals between the location-fixes are too big, valuable information about important small scale behaviour will be missed.

ABSTRACT Durban's “Golden Mile” is the city’s most prominent tourist attraction and contributed ± R225 million towards much needed job creation and poverty alleviation in the region during the 2007 financial year, a trend which is set to increase dramatically during the FIFA (Fédération Internationale de Football Association) 2010 Soccer World Cup, which was awarded to the Republic of South Africa. The City of Durban will host eight World Cup matches, including a semi-final at the newly designed Moses Mabhiba World Cup 2010 Stadium. The high incidence of violent crimes committed against tourists, which is also reported on in the international media, has caused the concern that if tourists perceive the beachfront to be unsafe they will be hesitant to visit Durban again, while the likelihood also exists that they might discourage other potential visitors. This paper is an attempt to provide input to the discourse on the matter based on empirical research. Much of the research on crime and tourism is founded on economic models of criminal behaviour. The current study contributes to the expanding crime and tourism literature by providing facts and accurate statistics instead of anecdotal information on violent crime and tourism, more specifically with regard to the so-called “street robberies”. From the data collected and analysed, it will become evident that during 2006, 90% of the street robberies reported to Golden Mile hotel security was not documented in the form of a case docket with the SAPS. Through the use of qualitative data analysis techniques such as theming, coding and categorising, the study will also reveal that all the respondents who completed the open-ended questionnaire are of the opinion that preliminary crime scene investigation of street robberies committed against tourists on Durban’s Golden Mile was, for a variety of reasons, ineffective. Finally, based on the relevant literature as well as the findings of the study, a number of recommendations will be put forward.

published_or_final_version / Anatomy / Master / Master of Philosophy