No description available.

This study compared traditional community analysis with stable-isotope trophic analysis to define process-based trophic elements of community structure in the eastern Gulf of Mexico, and developed a predictive capability regarding changes to fish community structure that would be expected from increasing eutrophication. Specifically, it used an existing trawl survey program (SEAMAP) to compare invertebrate herbivore (sponge and sea urchin) isotopes with groundfish isotopes, and then compared the resulting spatial patterns with spatial variation in community structure, as identified by cluster analysis. The comparison was applied to seven NMFS survey zones that extended offshore from the Caloosahatchee River, FL northwest to Mobile Bay, AL. Isotopic patterns were consistent with the presence of an oligotrophic-eutrophic spatial gradient in this region. δ15N values increased in the northwestward direction in herbivores and in each of the 17 fish species examined. In the southern NMFS survey zones, δ13C was elevated in shallow depths for individual fish species, but not in herbivores, indicating a higher proportion of benthically derived biomass contributed to the biomass of fish in the shallow parts of the southern NMFS zones. Fish community analysis using SIMPROF created a similar pattern, with distinct nearshore and offshore communities and also a northwesterly community transition. Among the 17 fish species, five appeared to have obligate dependence on either benthic or planktonic basal resources, while twelve species appeared to be have facultative relationships. Impairment of current water-quality (nutrients, turbidity, light transmission, chlorophyll a) is expected to lead to reductions in the abundance of both obligate and facultative benthic-dependent fishes.

Landsat imagery has been used successfully to assess burn severity and monitor post-fire forest structure in a variety of ecosystems, but to date there are few documented studies on its application in the eastern deciduous forests of the eastern United States. The occurrence of a wildfire in the Daniel Boone National Forest in2010 provided a rare opportunity for research into the use of Landsat data for assessing burn severity and its ecological effects. We used differenced normalized burn ratio (∆NBR) to quantify burn severity. The ∆NBR based burn severity classification had 70% agreement with a qualitative ground-based burn severity assessment. We also examined the relationship between the presence of an invasive species (Paulownia tomentosa), and our assessment of burn severity, where we found a weak but statistically significant relationship (adj R2 0.13, p<0.0001). We also examined the relationship between the normalized difference vegetation index (NDVI) and forest structure measurements. The relationship between NDVI and basal area was strongly and significantly related (adj R2 0.41, p<0.0001). The relationship of NDVI with stem density was weak but significant (adj R2 0.23. p=0.004). These results indicate that data from Landsat imagery have great potential for quantifying burn severity, identifying potential hotspots for invasive species, and assessing post fire forest structure in the eastern deciduous forest.

No description available.

Der Hedgehog (Hh)-Signalweg ist an der Entstehung verschiedener Tumorentitäten beteiligt. Es wird vermutet, dass die Signalwegskomponente Patched (Ptch) physiologischerweise als Oxysterolpumpe dient und ein Molekül - vermutlich ein Vitamin D3 Derivat - sezerniert, welches den Hh Signalweg durch Bindung an das Transmembranprotein Smoothened (Smo) hemmt. Durch inaktivierende Ptch Mutationen wird die Sekretion dieses Moleküls vermutlich gestört, was zu einer Aktivierung des Signalwegs führt. Vorarbeiten lassen vermuten, dass es sich bei dem sezernierten Vitamin D3-Derivat um 1α,25(OH)2D3 (Calcitriol) handeln könnte. Da Calcitriol seine antitumorale Wirkung neben der Hemmung der Hh-Signalkaskade auch über die Aktivierung des Vitamin-D-Rezepor (Vdr) -Signalwegs vermitteln kann, sollten in dieser Arbeit mögliche Schnittpunkte der Hh-Signalkaskade, des Vdr-Signalwegs und des Calcitriol Metabolismus untersucht werden. Zunächst ergaben die Untersuchungen, dass Ptch-defiziente Rhabdomyosarkom Zellen, verglichen mit Wildtyp-Ptch Zellen, eine verminderte Calcitriol-Synthese aufweisen, die vermutlich durch eine herabgesetzte Aktivität der 1α Hydroxylase bedingt ist. Die dadurch verminderte Calcitriol Konzentration ist wahrscheinlich die Ursache der gleichzeitig erhöhten Hh Signalwegsaktivität in den Zellen. Dies bestätigten weitere Untersuchungen mit dem 1α Hydroxylaseinhibitor Itraconazol an Ptch-/- Zellen. Weiterhin konnte gezeigt werden, dass Itraconazol mit Calcitriol hinsichtlich der Hemmung des Hh-Signalwegs kooperiert. Die verstärkte Hemmung ist aber unabhängig von einer Itraconazol-abhängigen Herabsetzung der 24 Hydroxylaseaktivität. Zudem zeigten die Untersuchungen, dass Calcitriol (neben der Aktivierung des Vdr Signalwegs) den Hh-Signalweg in Ptch / Zellen effizienter hemmt als Cyclopamin. Weiterhin konnte gezeigt werden, dass Calcitriol auch mit Cyclopamin bezüglich der Hemmung der Hh-Signalkaskade kooperiert. Weitere Untersuchungen bekräftigen die Hypothese, dass Calcitriol, ähnlich wie der bekannte Smo-Inhibitor Cyclopamin, an Smoothened (Smo) bindet. Daneben weisen die Untersuchungen darauf hin, dass 1α,25(OH)2D3 den Hh-Signalweg zusätzlich über einen nicht-kanonischen, Suppressor of fused-unabhängigen Weg hemmen könnte. Transfektionsuntersuchungen an Gli-Knock-Out-Zellen zeigten, dass Gli3 möglicherweise die Vdr-Expression und dadurch auch die Calcitriol/Vdr-vermittelte Proliferationshemmung von Calcitriol reguliert. Schließlich konnte im Tiermodell für BCC die antitumorale Wirkung von 100 ng/kg/d Calcitriol gezeigt werden. Die Studie zeigte die effektive Wirkung von Calcitriol, wenn die Substanz ab einem frühen Tumorstadium verabreicht wird. Daneben scheint die Dauer der Behandlung eine entscheidende Rolle für die antiproliferative in vivo Wirkung von Calcitriol zu spielen.

Southern Africa is characterised by an unpredictable environment with daily and seasonal temperature fluctuations. As a local or non-migratory endothermic species occurring over an altitudinal gradient from the Drakensberg to the coast of KwaZulu- Natal in southern Africa, Amethyst Sunbirds (Chalcomitra amethystina) experience challenging thermal conditions and increased energetic stress as a result of ambient temperature variation. Flexibility of metabolic rates within a species allows for the colonization of different habitats along an altitudinal and thus temperature gradient. It was predicted that over this altitudinal gradient Amethyst Sunbirds would exhibit variation in metabolic rates, particularly basal metabolic rates, pre- and postacclimation, as well as variation in hematocrit levels in winter and summer trials. It was also predicted that Amethyst Sunbirds would exhibit seasonal variation in metabolic parameters. Sunbirds were caught in a winter and summer season (2006-2007) using mist nets in three locations; Underberg (1553 m), Howick (1075 m) and Oribi Gorge (541 m). Upon capture, metabolic rate was measured indirectly by quantifying oxygen consumption (VO2) using flow through respirometry, at 5 and 25°C. Birds were then acclimated at 25°C for 6 weeks on a 12L:12D cycle. VO2 was measured postacclimation at 8 different temperatures (15, 5, 10, 20, 30, 28, 25 and 33°C). Hematocrit levels were taken pre-acclimation and pre-release. Winter and summer data were compared. In the winter trials it was found that there was little variation in VO2 between individuals from the same locality, whereas significant variation was observed at the same temperatures between localities and thus between altitudes. The subpopulation from the highest altitudinal site had the highest basal metabolic rate (BMR). Summer trials showed that metabolic rates did not differ significantly between altitudinal subpopulations of Amethyst Sunbirds, however, BMR was observed to decrease as altitude decreased. The comparison of seasonal data showed that Amethyst Sunbird subpopulations from Underberg and Howick showed higher post-acclimation VO2 values per temperature in winter than in summer trials. Post-acclimation resting metabolic rate (RMR) values for Howick subpopulations were generally higher in winter than in summer, Underberg Amethyst Sunbirds showed a significant difference between summer and winter RMR at 5 and 10°C and Howick sunbirds showed a significant difference in RMR between seasons at 5°C. The Oribi Gorge subpopulation, however, showed no significant differences in metabolic rate between any temperatures when comparing a summer and a winter season. Thermal neutral zones of all of the subpopulations of Amethyst Sunbirds shifted between the winter and summer trial period. This study thus emphasized the need to understand plasticity in metabolic rates and acknowledge altitudinal and seasonal differences within a species, in order to make accurate predictions about a species thermal physiology and responses to changes in ambient temperatures. In particular, the variation in BMR, which is usually used as a species specific value, should be acknowledged in comparative studies of avian metabolic rates or in climate change models. / Thesis (M.Sc.) - University of KwaZulu-Natal, Pietermaritzburg, 2007.

Les observations détaillés indiquent que la chaîne de Xuefengshan peut être divisé en deux parties, la zone Ouest, caractérisée par des plis-coffrés, et la zone Est à déformation ductile polyphasée. Elles sont séparées par le chevauchement principal vers l'Ouest. Dans la zone Est, les structures dominantes sont des plis à vergence NW associés à des schistosités pénétratives de plan axial et des linéations NW-SE. De l'ouest vers l'est, la schistosité montre un style en éventail. Les roches du socle affleurent seulement autour des plutons triasiques. Les roches de la chaîne de Xuefengshan sont généralement déformées ductilement mais faiblement métamorphisées, toutefois, sous la croûte supérieure, on met en évidence un décollement ductile et synmétamorphe qui accommode les différences de déformation entre les roches sédimentaires et le socle. L'architecture de la chaîne du Xuefengshan résulte de la déformation polyphasée: la première phase (D1) est caractérisée par un cisaillement ver le nord-ouest. Le deuxième phase (D2) correspond au rétro-plissement vers le SE. La dernière phase (D3) est un événement de raccourcissement NW-SE avec des plis doits et schistosités verticales. En combinant ces nouveaux résultats structuraux avec les données géochronologiques, la chaîne de Xuefengshan est interprété comme un orogène intracontinental formé au Trias moyen. Cette chaîne résulte du sous-charriage continental d'une partie du bloc de Chine du Sud, en réponse à l'effet lointain de la subduction de la plaque de Paleo-Pacifique vers le nord-ouest.

Basal cell carcinoma is a form of a non-melanoma skin tumour, that commonly forms over the sun exposed regions of the head and neck. Investigation of the rate of occurrence at different sites on face and neck shows considerable variation from site to site. The inner canthus has a disproportionate number when compared to more exposed sites. The eye brow ridge, cheek bone and nose limit the field of view of the inner canthus, thus it is expected to receive less radiation than other more exposed regions. To explain the disproportionate rate, it is hypothesised that a portion of radiation incident onto the eye is reflected to the inner canthus. The aim of this thesis is to investigate the contribution that the radiation reflected off the surface of the eye makes to the overall dose on the inner canthus. The inter reflections between the eye and inner canthus were studied through the use of the ray tracing program Zemax. Zemax was used to trace rays in a non sequential mode incident onto a model eye and periorbital region. To obtain the models of the eye and periorbital region, both magnetic resonance imaging and a casting process was investigated, with the later being superior for our uses. With the model obtained, it was used in a series of three dimensional ray tracing programs. On a macroscopic scale there is a small increase in the irradiance on the inner canthus (2 % over a 1 cm2 area). Peaks of high irradiance (19 % increase in irradiance above direct irradiance) were discovered over the surface when the detector was divided into 200 mm elements. It was concluded that these increases above the direct irradiance in these small regions, increases the possibility of the occurrence of a Basal cell carcinoma. Individual facial geometry, will greatly effect the location and size of these peaks and as a result an experimental method to measure the dose distribution across the inner canthus was proposed. Initially it was planned to use polysulphone film to measure the erythemal dose on the inner canthus. Results from the modelling indicated that any measurements made had to be at a high spatial resolution. Polysulphone film was found to be inadequate for this, due to its large uncertainties. An alternative method was investigated so that a population study could be performed in future studies using visible radiation and high dynamic range images gave a simple and effective clinical assessment tool. The high dynamic range images showed hot spots in the irradiance across the inner canthus agreeing with the model. The small spots of high relative irradiance may not be the only reason for the increased rate in this region. Greater skin sensitivity and absence of sun screen use at this site are other possibilities. It is believed however that the irradiance distribution across the inner canthus on a microscopic scale goes a long way to increasing the risk for certain people.

Thesis (Ph.D.)--Mississippi State University. College of Veterinary Medicine. / Title from title screen. Includes bibliographical references.

Thesis (Ed. D.)--Illinois State University, 2001. / Title from title page screen, viewed April 20, 2006. Dissertation Committee: Susan Davis-Lenski, Joseph Braun (co-chairs), Anthony Lorsbach. Includes bibliographical references (leaves 115-139) and abstract. Also available in print.