Jane Austen: her family and early life, and the relationship between her juvenilia and mature novels

Thesis (M.A.)--Boston University, 1948. This item was digitized by the Internet Archive

How the brain constructs stable visual representations: Cortical and subcortical mechanims

Our eyes are constantly moving yet our perception remains stable. Neurons in lateral intraparietal cortex (LIP) update spatial representations by "remapping" visual information at the time of an eye movement. In order for remapping to occur over a wide range of eye movements, neurons must have access to visual information from the entire visual scene. The forebrain commissures appear to be the primary pathway for the transfer of visual information across hemispheres but they are not necessary. If the forebrain commissures are transected, behavior dependent on accurate spatial updating is impaired, but recovers. In three sets of experiments we examined different mechanisms of spatial updating in split brain monkeys. First, we studied the relationship between neural activity in LIP and the behavior of the monkey. We found across the population a small but significant relationship between the activity in LIP and the performance of the split brain monkey on the double-step task. This result showed that information about the opposite visual field still reaches LIP, and this activity contributes to the overall behavior of the monkey.Second, we determined if LIP neurons in the split brain monkeys have bilateral receptive fields. One explanation for the observed across-hemifield remapping is that information from both visual fields are represented in a single hemisphere. We found no neurons in the split brain monkeys with ipsilateral representations. We concluded that there must be a subcortical source for the across-hemifield remapping observed in the split brain monkeys.Third, we examined the difference in spatial updating between intact and split brain monkeys in the superior colliculus (SC). In both the intermediate layers of the SC and LIP, neural activity is selectively reduced for the across-hemifield condition in split brain compared to intact animals. This suggest that remapping activity is passed from LIP to the intermediate layers of the SC. In contrast, remapping activity in the superfical layers did not differ between the intact and split brain monkeys. It may be that the superfical neurons contribute to recovered remapping activity observed in LIP

Transcription of the human and rodent SPAM1 / PH-20 genes initiates within an ancient endogenous retrovirus

BACKGROUND: Sperm adhesion molecule 1 (SPAM1) is the major mammalian testicular hyaluronidase and is expressed at high levels in sperm cells. SPAM1 protein is important for penetration of the cumulus cell layer surrounding the ovum, and is also involved in zona pellucida binding and sperm intracellular signalling. A previous study had identified SPAM1 as one of the many human genes that initiate within a transposable element. RESULTS: Examination of the human, mouse and rat SPAM1 loci revealed that transcripts initiate within the pol gene of an endogenous retrovirus (ERV) element. This is highly unusual, as all previously identified ERV-initiated cellular gene transcripts initiate within the viral long terminal repeat promoter. The SPAM1 locus therefore represents an example of the evolution of a promoter from protein-coding sequence. We have identified novel alternative promoter and splicing variants of human and murine SPAM1. We show that all transcript variants are expressed primarily in the testis and are predicted to encode identical proteins. CONCLUSION: The testis-specific promoters of the human and mouse SPAM1 genes are derived from sequence that was originally part of an ERV pol gene. This represents the first known example of an ERV-derived promoter acting in a gender-specific manner

Discrete charges on a two dimensional conductor

We investigate the electrostatic equilibria of N discrete charges of size 1/N on a two dimensional conductor (domain). We study the distribution of the charges on symmetric domains including the ellipse, the hypotrochoid and various regular polygons, with an emphasis on understanding the distributions of the charges, as the shape of the underlying conductor becomes singular. We find that there are two regimes of behavior, a symmetric regime for smooth conductors, and a symmetry broken regime for ``singular'' domains. For smooth conductors, the locations of the charges can be determined up to a certain order by an integral equation due to Pommerenke (1969). We present a derivation of a related (but different) integral equation, which has the same solutions. We also solve the equation to obtain (asymptotic) solutions which show universal behavior in the distribution of the charges in conductors with somewhat smooth cusps. Conductors with sharp cusps and singularities show qualitatively different behavior, where the symmetry of the problem is broken, and the distribution of the discrete charges does not respect the symmetry of the underlying domain. We investigate the symmetry breaking both theoretically, and numerically, and find good agreement between our theory and the numerics. We also find that the universality in the distribution of the charges near the cusps persists in the symmetry broken regime, although this distribution is very different from the one given by the integral equation.Comment: 46 pages, 46 figures, submitted to J. Stat. Phy

Standardising Morphological Trait Schemes: Introducing the Global Ant Database

Dissertação de mestrado em Biologia, apresentada ao Departamento de Ciências da Vida.Dendrochronology is based on the study of tree-ring pattern variations in relation to time and is at present the only dating technique that provides dates with annual or sub-annual resolution. Due to the climatic signal contained in these patterns, it is also possible to determine the provenance of the wood through comparison of tree-ring series derived from the objects under study with appropriate master chronologies. By allowing such a precise dating of wooden materials, dendrochronology is a fundamental tool used in archaeological and historical investigations. In this work, dendrochronology was used to date and to determine the provenance of wooden finds derived from two archaeological excavations in the Netherlands: the Martinikerkhof (St. Martin’s churchyard) situated in Groningen and from Dorestad (present Wijk Bij Duurstede). With the same aim, we investigated samples from the structural timbers of historical buildings from the city of Venlo, also located in the Netherlands. The 26 researched coffins from the Martinikerkhof had been built from oak timbers (Quercus sp.) derived from trees grown in different regions of Germany and France. Furthermore, the dates determined indicated that the excavated section of the churchyard was used as a burial ground since the mid 16th century until at least, the second half of the 18th century. From the ancient town of Dorestad, 43 barrels found reused as water wells were investigated and determined to have been built either with silver fir (Abies alba Mill. ) or with oak wood (Quercus sp.). The oak wood was derived from trees grown in forests of western Germany. Both kinds of barrels were contemporary and dated around the 8th century, the exception being one of the oak barrels, which dated to the 12th century. Oak (Quercus sp.) was the only species found among the wood employed in the construction of the 12 researched buildings from the town of Venlo. The determined provenances suggest the timbers would have been harvested from Belgium forests, while in other cases it would have come from Germany, and south of The Netherlands. Only one of the buildings could not be dated. However, the dating results for the rest placed their construction in the Medieval and early Modern periods, meaning they had survived the second World War bombardments.A dendrocronologia baseia-se no estudo de variações nos padrões formados por anéis de crescimento de árvores ao longo do tempo e é a única técnica que, actualmente, permite a determinação de datas com resolução anual ou sub-anual. O sinal climático contido nestes padrões permite também, determinar a origem da madeira através da comparação das séries dendrocronológicas obtidas a partir dos objectos em estudo com cronologias de referência apropriadas. Por permitir tal detalhe no estudo de objectos de madeira, o método estabelece-se como uma ferramenta fundamental em investigações históricas e arqueológicas. No presente trabalho, o método dendrocronológico foi empregue na datação e determinação da origem da madeira empregue em achados recuperados de excavações arqueológicas, realizadas em dois locais nos Países Baixos: em Martinikerkhof (Cemitério de S. Martinho), situado em Groningen e na antiga cidade de Dorestad (actual Wijk Bij Duurstede). Com o mesmo fim, foram analisadas amostras derivadas das madeiras estruturais de edifícios históricos da cidade de Venlo, também nos Países Baixos. Da excavação no Cemitério de S. Martinho, 26 caixões contruídos a partir de madeira de carvalho (Quercus sp.) foram analisados e determinou-se que a madeira utilizada na sua construção foi obtida de árvores crescidas em diferentes regiões da Alemanha e França. Além disso, as datas determinadas indicaram que a secção das escavações foi utilizada como cemitério desde meados do século XVI até pelo menos, a segunda metade do século XVIII. Na antiga cidade de Dorestad, 43 barris encontrados reutilizados como suporte para poços de água foram investigados e verificou-se terem sido construídos ou com abeto (Abies alba Mill.) ou com madeira de carvalho (Quercus sp.). Determinou-se como proveniência da madeira de carvalho a região Oeste da Alemanha. Ambos os tipos de barris foram datados no século VIII, com excepção de um dos barris de carvalho, que datou no século XII. A única espécie encontrada entre as madeiras aplicadas na construção dos 12 edifícios pesquisados da cidade de Venlo foi carvalho (Quercus sp.). As proveniências determinadas sugerem que as árvores teriam crescido em florestas da Bélgica, enquanto que noutros casos, teria vindo da Alemanha e do sul da Holanda. Apenas um dos edifícios não pode ser datado. No entanto, as datas determinadas para os restantes coloca a sua construção, no período Medieval e inicio do Moderno, mostrando que sobreviveram aos bombardeamentos da Segunda Guerra Mundial

Transcriptional Regulation and Cell Transformation by v-Jun

v-Jun, a mutated derivative of the c-Jun transcription factor, is the transforming oncoprotein of an avian sarcoma virus. v-Jun is thought to cause cell transformation and tumorigenesis by the mis-regulation of certain target gene promoters. v-Jun can both activate and repress gene transcription compared to c-Jun, however little is known about the underlying mechanisms and the identity of the critical "effector" target gene(s) responsible for cell transformation and tumorigenesis by v-Jun. To investigate the mechanisms of transcriptional regulation by v-Jun, a comparative study was undertaken of two gene promoters, bkj and collagenase, which are respectively activated or repressed by v-Jun. Promoter mutagenesis experiments were performed to investigate the effects of Jun binding site position and core promoter element sequences on transcriptional regulation by v-Jun. The primary conclusion was that these factors alone did not determine whether target promoters were activated or repressed by v-Jun. However, alterations in the level of transcriptional activation and fold induction of the variant promoters by v-Jun implied that binding site position and core promoter sequences did influence transcriptional regulation by Jun proteins. This analysis also suggested that v-Jun regulated transcription by different mechanisms at different target promoters. Further work investigated the relationship between transcriptional activation of v-Jun target promoters and cell transformation using DeltavJ-hER, an amino-terminally truncated v-Jun protein fused to the hormone-binding domain of estrogen receptor-alpha. This chimaeric protein was previously shown to induce activation of v-Jun target genes and cell transformation in an estradiol-dependent manner, despite lacking the v-Jun transcriptional activation domain. The estrogen receptor activating function-2 (AF-2) domain was proposed to substitute for this v-Jun domain, implying that estradiol-dependent transcriptional activation of v-Jun target gene promoters by AvJ-hER was required for cell transformation. To test this hypothesis, an inactivating mutation was introduced into helix 12 of the AF-2 domain, which mediates estrogen receptor binding to co-activator proteins. The mutant AvJ-hER protein was inactive in transcription and cell transformation assays, confirming that these processes required AF-2 function. Many estrogen receptor co-activator proteins have histone acetyltransferase activity, however the p300 histone acetyltransferase domain was unable to substitute for the estrogen receptor AF-2 domain function to induce either transcriptional activation or cell transformation. In conclusion, while the mechanisms responsible for transcriptional activation and repression by v-Jun remain unclear, these results support the hypothesis that transcriptional activation of positive v-Jun target gene promoters is required for cell transformation

Erectile dysfunction: is it really that difficult to talk about? An interpretative phenomenological exploration

Background This thesis explores the disclosure of erectile dysfunction to healthcare professionals by asking men with erectile dysfunction, their partners and healthcare professionals to recall their experiences of such conversations. Erectile dysfunction can be a difficult subject to broach or disclose, and as a result, it is considered that the condition is under reported and therefore under diagnosed. In the light of erectile dysfunction being considered a possible marker of cardiovascular risk this thesis seeks to highlight the issues around disclosing the condition with a view to improving disclosure rates and therefore informing subsequent cardiovascular risk assessment. Literature There is a body of literature which demonstrates that erectile dysfunction is a common issue which is correlated with many physical and mental health conditions. Specifically within populations of men with known cardiovascular disease prevalence rates of erectile dysfunction can be as high as 70%. Literature which explores the experience of having erectile dysfunction and disclosing it to a healthcare professional demonstrates that this is a conversation which is complex and is often avoided by both men with erectile dysfunction and healthcare professionals alike. In light of literature which demonstrates that ED and cardiovascular disease are linked, and that which demonstrates that disclosing ED is difficult there is a gap in the literature which specifically explores the disclosing of ED when it is a known marker of cardiovascular disease risk. Research Process Following a cardiac event, men who identified themselves as having erectile dysfunction, their partners and healthcare professionals to whom a disclosure may be given, were approached and asked to describe their experiences. The study was designed using a phenomenological perspective so as to allow the thoughts and experiences of the participants’ and researcher to be used to provide an illustration of the disclosure of erectile dysfunction, particularly when considered as a precursor and marker of cardiovascular risk. The initial analysis used a thematic approach but this was found to be problematic in relation to the depth of the data that was captured and therefore a second analysis was undertaken, the results of which are presented as the findings of this study. The second analysis of data used a staged approach favoured in interpretative phenomenological analysis (Smith et al. 2009), which facilitated an analysis of the interview transcripts descriptively, interpretatively and linguistically. This latter analysis provided a unique perspective in relation to the topic which is acknowledged as difficult to discuss, and resulted in the linguistic tools which were used by the participants being identified as evidence for the embarrassment; this was identified as one of the themes which emerged from the descriptive analysis. Analysis and Findings Analysis of the interview data with men and their partners identified the themes of: the impact that erectile dysfunction has had on their lives, disclosure (or not) of erectile dysfunction and erectile dysfunction in contemporary society. The interviews with healthcare professionals generated themes which resonated with those from the men as well as focusing on professional issues of ownership in relation to ED disclosure, anxieties in relation to such discussions and experience of receiving disclosures. All of the themes have been extensively written about in relation to other health related issues but they have not been explored explicitly in relation to the disclosure of erectile dysfunction and therefore a unique position of the findings in relation to the existing literature is evidenced within Chapter Nine. The discussion located the findings specifically within existing literature related to embarrassment, stigma and medicalisation. The discussion of the analysed data within the context of the existing literature is then extrapolated to the current clinical environment and changes to clinical practice are suggested by linking the findings to practice. Suggested adaptations to clinical practice focus on improving the confidence of all involved in the disclosure of erectile dysfunction in having such conversations, by increasing the opportunities for them to occur and improving the confidence of all involved in managing such situations