VictorJuiz/thesis huggingface dataset:
Photometric properties of low-redshift galaxy clusters

A comprehensive multicolor CCD photometric study has been made for a sample of forty-five low-redshift (0.04 $\leq$ z $\leq$ 0.18) rich clusters of galaxies, in order to compare many of the properties associated with clusters. Accurate photometric measurements in R, B and I were generated, to sufficiently faint levels, allowing the contribution of dwarf galaxies to be considered. In thesis we have investigated the color magnitude relation for early type galaxies. Our results are consistent with population synthesis models that explain the CMR as an effect produced by varying metallicities and passive evolution. The universality of the CMR slope is established, and rules out any major star formation activity in cluster early-type galaxies during the last 11 Gyr. Color information is used as an additional constraint in generating the luminosity function (LF) of cluster galaxies. The analysis of the whole sample reveals that the characteristic magnitude of cD clusters varies with richness. Non-cD clusters present small variations that are consistent with the hypothesis of universality of their LF. 100% completeness is reached in the range of absolute magnitude between $M\sb{R}$ = $-$25 and $M\sb{R}$ = $-$17($H\sb{o}$ = 50 km s$\sp{-1}$Mpc$\sp{-1};q\sb{o}$ = 0) in a subsample of twenty-two clusters. Some evidence has been found to indicate that cD clusters have depleted a large number of dwarf galaxies. Based on these results, an alternative scenario for cD galaxy formation has been proposed.
Non-marine sequence stratigraphy of the Sego Sandstone and Upper Castlegate Sandstone, Upper Cretaceous, Book Cliffs, Utah, United States of America

The Sego Sandstone and Upper Castlegate Sandstone are laterally equivalent formations of the Upper Cretaceous Mesaverde Group which crop out along the Book Cliffs of eastern Utah and western Colorado and represent sediment shed into a foreland basin from the Sevier orogenic belt to the west. The studied interval contains three regional unconformities which bound stratigraphic sequences around 100m thick and of 1-3 m.y. duration, here termed high order sequences I-III. The high order sequence boundaries display increasing depth of erosion northwestward toward the Sevier orogenic belt and mark changes in sediment dispersal patterns and provenance, none of which can be explained by eustatic sea-level falls. Their formation is attributed to isostatic rebound and erosion of proximal parts of the foreland basin following thrust events in the adjacent Sevier orogenic belt. In the southeastern part of the study area, high order Sequence II ($\sim$Sego Sandstone) contains several ($>$4) nested stratigraphic sequences around 20m thick and of $\sim$100 k.y. duration, here termed low order sequences. The low order sequence boundaries are disconformities rather than angular unconformities and are not marked by changes in sediment dispersal patterns or provenance. Each of these low order sequences consists of: (a) a lowstand systems tract of incised valleys (up to 14 m thick) filled with tidally-dominated estuarine deposits and (b) a transgressive systems tract of marine shale. No highstand systems tracts are preserved. The origin of these sequences (eustatic/tectonic) cannot be determined. When traced to the northwest, the low order sequence boundaries become conformable and unrecognisable, and no low order stratigraphic sequences corresponding to those in the Sego Sandstone can be recognised within the alluvial Upper Castlegate Sandstone. The observed nested sequence architecture of the Mesaverde Group is considered to be controlled by variation in subsidence rate related to the emplacement and erosion of thrust sheets in the adjacent Sevier orogenic belt. During emplacement of thrust sheets, subsidence rates in proximal areas of the basin were sufficiently high to offset any low order baselevel falls, resulting in deposition of a conformable fluvial succession. In distal parts of the basin where long term subsidence rates were lower, low order baselevel falls produced relative falls in sea-level and generated spatially restricted low order sequences.
New heroes, gender, race, fans and comic book superheroes

This study offers an ethnographic account of one comic book publishing company's attempt to address divergent audiences through new heroes and how the readers of these texts come to understand them through interpretive strategies and subcultural practises specific to the comic book industry and comic book fandom. Specifically, this study focuses on the African American comic books published by Milestone Media and how fans relate to the stories and the new Black heroes according to six fundamentally interconnected principles and points of comparison. The interpretive strategies used by comic book fans revolve around (i) their recognition of Milestone's corporate and creative identity as the mainstream publisher of African American comics; (ii) their awareness of the debate between Milestone and other African American comic book creators regarding the authenticity of ethnic representation; (iii) their reliance on subcultural principles specific to comics fandom, such as the collecting principle whereby the reader's recognition of specific artists and/or writers allows the fan to accumulate cultural capital within the subculture; (iv) the fan's knowledge of genre history and of earlier attempts to create Black heroes; (v) the fan's familiarity with formalized genre conventions and Milestone's place as an innovative publisher which retains most or the "classic" elements of the superhero formula, and (vi) in comparison to the market-dominating comic books published by other companies which promote a popular trend of gender extremism. For many fans the Milestone superheroes function as a focal point for interpreting revisionist notions of African American characters in comparison to more mainstream comic book ideals, and further, they facilitate a progressive interpretation of Black masculinity which incorporates intelligence with physicality. This research is an attempt to contribute to the current debate in Cultural Studies between perceptions of media texts as agents of hegemony and of audiences as active resistors. Rather than either of these extremes, this study argues that the reading of comic books is interpreted according to the ideological encodings of the producers and the socially positioned, fandom-based, decodings of the audience.
Somatostatin-28 and somatostatin-14, secretion and function in the canine gastrointestinal tract

There are two circulating biologically active forms of somatostatin, somatostatin-28 (S-28) and somatostatin-14 (S-14). Previous studies examining somatostatin release after nutrient ingestion did not determine whether measurements of total somatostatin are representative of responses by individual S-28 and S-14 components. The differential regulation by muscarinic mechanisms and gastric acid of S-28 and S-14 responses after solid meal ingestion and after insulin hypoglycemia were examined. The roles of S-28 and S-14 in the regulation of gastric acid and gastrin secretion were investigated and the somatostatin receptor subtype(s) (SSTR) mediating these effects were characterized. Meal ingestion increased plasma SLI three-fold and elevations of S-28 and S-14 were equivalent. Postprandial gastric acid secretion accounted for $\sim$50% of the rise in both S-28 and S-14. Whereas increased intraluminal acidity directly stimulated the rise in S-14, the S-28 response to gastric acid required cholecystokinin as a cofactor. Similarly, nutrient-independent vagal activation of S-14, but not S-28 secretion, was directly dependent upon increased gastric acid secretion. After nutrient administration, muscarinic excitatory pathways regulate S-28 secretion whereas muscarinic inhibitory pathways regulate S-14 secretion. This inhibition was amplified at neutral pH and was associated with an increase of meal-stimulated gastrin release. Reciprocal functional coupling of gastrin and S-14 secretion linked by muscarinic pathways was suggested by the finding that at neutral pH, muscarinic inhibition of gastrin was reversed by administration of a somatostatin antagonist. S-14, but not S-28, was shown to inhibit gastrin-stimulated acid secretion via an endocrine mechanism and was found to participate in intestinal fat-mediated inhibition of acid secretion. S-14 was selectively released after fat to plasma elevations that inhibited gastrin-stimulated acid secretion and this inhibitory effect by S-14 was reversed with a somatostatin antagonist. These inhibitory actions of S-14 on gastrin-stimulated gastric acid secretion and gastrin release were mediated through SSTR2. In conscious dogs, gastric acid regulates S-28 and S-14 after nutrient ingestion by separate mechanisms; muscarinic pathways differentially regulate S-28 and S-14 secretion and this effect is linked to the state of gastric acidity; and S-14, via activation of SSTR2, inhibits gastric acid secretion and gastrin release.
Structural and functional divergence of the transcription factor Pit-1, analysis of the pou and transactivation domains

The structurally related polypeptide hormones prolactin (PRL) and growth hormone (GH) are produced by specific cell types in the pituitary. A third pituitary member of the GH/PRL family, somatolactin (SL), has been identified in fish species. In mammals, high level expression of the PRL and GH genes is dependent on the DNA binding transcription factor Pit-1. I have cloned a homologous Pit-1 cDNA from a distantly related vertebrate species Oncorhynchus tschawytscha (chinook salmon) and have examined whether divergence of Pit-1 structure during evolution might be constrained by a requirement for efficient activation of PRL, GH, and SL genes. The salmon Pit-1 POU and transactivation domains are 87% and 57% identical, respectively, with those of rat Pit-1. Our chimeric Pit-1 studies have demonstrated that the POU and transactivation domains are functionally interchangeable. In the rat, the transactivation domain of Pit-1 can be alternatively spliced to yield Pit-1$\alpha$ and Pit-1$\beta$ isoforms; the $\alpha$-isoform lacks a 26 amino acid insert present in the $\beta$ isoform. Either of these Pit-1 isoforms activates the rat GH gene but only the shorter $\alpha$-isoform activates the rat PRL gene. In salmon the Pit-1 transactivation domain constitutively includes two inserts: a $\beta$-insert homologous to the mammalian sequence, and a unique $\gamma$-insert (33 amino acids) encoded by an exon that is absent in rat Pit-1. Using site-directed mutagenesis I demonstrate that salmon Pit-1 activates the salmon PRL and SL genes efficiently only when both $\beta$ and $\gamma$ inserts are present. These data argue that retention of $\beta$ and $\gamma$-insert coding sequences in the salmon pit-1 gene was constrained by at least two target genes. An opposite pattern of splicing evolved in the rat pit-1 gene where efficient removal of the $\beta$-insert became a necessary step for potent activation of the PRL gene. Unlike the PRL genes, activation of both the salmon and rat GH genes is far less dependent on the presence or absence of the Pit-1 insert sequences. Rapid evolutionary divergence of prolactin gene function may have resulted in changes in Pit-1/protein interactions to accommodate new patterns of transcriptional control by developmental or physiological factors.
The naturalistic imperative in cognitive science

This thesis reviews current progress in cognitive science towards satisfying the naturalistic imperative. Careful attention is paid to distinguishing metaphysical naturalism from methodological naturalism. Following this, methodological naturalism is further clarified as the set of imperatives: analyse, formalise, and mechanise. It is argued that simulation on its own is insufficient for satisfying these imperatives. Instead it must be supplemented and constrained by existing psychological theory which will indicate the relevant features for comparison in any simulation that seeks to be an explanation of human cognition. Therefore, we turn to an examination of current work in cognitive psychology. Specifically, we examine areas where attempts are being made to analyse and formalise cognition in terms of more basic psychological processes. So, the thesis proceeds to examine current work on categorisation and the nature of concepts, memory, problem solving, and inference. It shows how each can be considered a basic process in terms of which the rest of cognition might be analysed and formalised. However, we also discover that in each of these areas the naturalistic imperative is being seriously frustrated by a combination of conceptual and methodological problems. It is further shown that these problems are not independent but stem from a deep problem concerning the relationship between the two central notions of representation and relevance. The thesis argues for a very tight interdependence between the two notions so that whenever one is being used theoretically the other is being presupposed. In turn, it argues that this interdependence is frustrating current attempts to naturalise cognition. What then follows is an examination of attempts to break out of this bind by independently naturalising representation or relevance. These two projects are shown to fail precisely because they cannot break the interdependence between representation and relevance. It is argued that what is behind this representation-relevance problem is a very serious problem in any attempt to naturalise the notion of relevance. Finally, there is a discussion of what follows for philosophy and cognitive science if relevance cannot be completely naturalised.
Syntactic dependencies in Mandarin Chinese

This thesis investigates two kinds of syntactic dependencies in Mandarin Chinese: uninterpretable feature checking of clause-level functional heads and dou quantificational binding. Three issues are discussed with respect to checking: object shift, yes/no questions, and the aspect particle le raising. Chinese object shift is argued to be triggered by a focus marker which adjoins to an object. This study also presents a unified treatment of various types of yes/no questions in Chinese. The uninterpretable (Q) of yes/no question C is checked either by the merged particle ma, by overt movement of bu/mei(you)-V from $\Sigma$ to C, or by covert movement of (Q) of shi-bu-shi and A-not-A words. In both object shift and questions the optionality between overt and covert checking occurs. The thesis argues that the strong value of the feature strength of a functional head can be triggered by a certain feature in its complement domain. Thus the choice of overt vs. covert checking can be determined in the computation. The thesis also explains the interactions between yes/no questions and negation by Relativized Minimality and feature compatibility. Furthermore, the thesis argues that sentence final le is base-generated in I and moves to C. As for dou quantification, it is shown that a licenser of dou can be an element which is capable of measuring the eventuality, a universal quantifier, an interrogative operator of a WH variable, or an element which has the word wulun 'no-matter' adjoined to it. A pronominal binding approach is adopted rather than a movement checking or unselective operator binding approach. Dou binding allows multiple licensers and the Ba/Bei-phrase blocking effect is explained by the notion of Complete Functional Complex. Like checking, dou binding also respects the Shortest Distance Principle. When dou's licenser has a dependent, whether it is a trace or an operator variable, the dependent must be base-generated in the same clause where dou occurs. Based on the case studies of both checking and binding, the thesis advocates a unified treatment to these two kinds of syntactic dependencies in the computation system.
Impact of liquid droplets on solid surfaces and its applications to carryover deposition in kraft recovery boilers

Carryover deposition can cause severe fouling of convective heat transfer surfaces in kraft recovery boilers. The tendency of molten carryover particles to be captured by tube surfaces strongly affects the fouling rate, but little information is available to predict this tendency. This work is the first to study the dynamic capture of liquid droplets upon impact on solid surfaces as applied to molten carryover deposition tendency in kraft recovery boilers. Liquid droplets analogous to molten carryover were used to investigate the droplet capture behavior. Deformation, spread, recoil, and/or rebound of a droplet upon impact on solid surfaces were quantitatively studied using a fast shutter-speed Charge Coupled Device (CCD) camera. The impact velocity and the liquid viscosity were found to have the strongest effect on maximum spread, while the static contact angle, viscosity and solidification significantly influence the tendency of a droplet either to deposit or to rebound. A semi-empirical model was developed to predict the maximum spread as a function of the Reynolds number, the Weber number and the static contact angle. The maximum spread increases with the Reynolds number and the Weber number: the effect of the contact angle is less important. Predicted results agree well with the experimental data from different sources. An isothermal rebound model was developed from experimental data to predict the tendency of a liquid droplet either to deposit or to rebound as a function of the maximum spread and the static contact angle. These results may be used to predict the tendency of molten carryover capture upon impact, if the carryover particle size, impact velocity, physical and thermal properties and substrate surface temperature are known. When the effect of solidification is insignificant, the tendency, of carryover to deposit or to rebound can be predicted using the rebound model. When rapid solidification occurs upon impact on a cold surface, all carryover droplets freeze and are captured. Experimental observations also suggest that the ejection of small splat droplets during the impact of molten droplets on a cold surface could be a mechanism for the production of the 10 to 100 $\mu$m intermediate particles found in precipitator dust.
Sex ratios of sea turtle hatchlings, direct and indirect estimates

To generate more data on sex ratios of sea turtle hatchlings, I developed a simple method of collecting daily mean sand temperatures on nesting beaches. Sand temperature can be used as an index of sex ratio. I then measured sand temperatures and sampled gonads of hatchlings of two sea turtle species on a nesting beach in Suriname during 1993. From histological analysis of the gonads, combined with information on the relative numbers of turtles nesting during the season, I generated overall estimates of sex ratio for green sea turtles (63.8% female) and for leatherback turtles (69.4% female). Relative numbers of male and female hatchlings varied throughout the season, and this corresponded to changes in sand temperatures and rainfall. From historical rainfall records and from past records of nesting frequency, I estimated overall sex ratios for another 13 seasons. Seasonal sex ratios fluctuated yearly. A revised estimate of the pivotal temperature (that constant incubation temperature which produces equal numbers of each sex) of green turtles in Suriname was 29.4$\sp\circ$C; this was slightly higher than past estimates. The transitional range of temperature (TRT), which is the range of incubation temperatures over which both sexes are produced, spanned several degrees. Metabolic warming was monitored in leatherback nests. It was found that eggs were about 0.8$\sp\circ$C warmer on average than the surrounding sand during the thermosensitive period of sexual differentiation. Because the leatherback has a narrow TRT, the influence of metabolic warming on sex ratio probably is restricted to a narrow range of incubation temperatures. Lastly, a new method of estimating sex ratios was devised, based on the rate of development of eggs and prevailing incubation temperatures. In general, nests with shorter incubation times produce mostly females and nests with longer incubation times produce mostly males. This relationship could be useful for generating predictions of sex ratio from natural nests for which only the incubation duration is known. In addition, by comparing this relationship from laboratory and field studies, it was possible to quantify the time it takes loggerhead hatchlings to dig up from the nest once they have hatched.
Reduced data requirements for phase-contrast MR angiography

A class of magnetic resonance angiography (MRA) methods, called time-of-flight (TOF), seems to be preferred over a second class of methods called phase-contrast (PC), even if the latter provides a greater suppression of static tissues surrounding blood vessels. A major reason for the lack of popularity of PC methods is the significantly longer imaging time required in PC angiography. In this thesis, it is recognized that a large portion of the information acquired in PC MRA is either redundant, or simply discarded. This suggests that faster PC methods could be designed if one can avoid acquiring unnecessary information. PC methods having reduced data requirements are developed in chapters 2 and 3; these methods achieve such a reduction by encoding velocity information in both the phase and the magnitude of a voxel, instead of using only the phase, as in conventional PC MRA. The basic idea that allows the encoding of velocity information in both phase and magnitude is very simple: if two complex numbers are added together, the phase of one of them affects both the phase and the magnitude of the sum. As in conventional PC MRA, velocity information is encoded into the phase of the magnetization (which is represented by a complex number). However, unlike conventional PC MRA, the methods introduced in chapters 2 and 3 generate a sum of complex numbers, forcing the velocity-induced phase shifts to be encoded in both phase and magnitude in the resulting image. In chapter 2, this sum occurs as ghosts of different orders are superposed in the object domain. In chapter 3, the sum occurs as echoes having different flow sensitizations overlap in the same acquisition window. It is recognized in this thesis that there are degeneracies in the acquisition process, in phase-contrast MR angiography. The methods presented in chapters 2 and 3 prove that these degeneracies are not a fundamental limitation of the phase-contrast approach, since they can be partly eliminated.