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Unpublished Observations (unpublished + observation)
Selected AbstractsLow algal carbon content and its effect on the C : P stoichiometry of periphytonFRESHWATER BIOLOGY, Issue 11 2005PAUL C. FROST Summary 1. We examined the contribution of algal cells to periphytic organic carbon and assessed the effects of variable biomass composition on the carbon : phosphorus (C : P) ratio of periphyton. We compiled more than 5000 published and unpublished observations of periphytic carbon : chlorophyll a (C : Chl) ratios, an index of algal prevalence, from a variety of substrata collected from lake and low-salinity coastal habitats. In addition, we converted estimates of algal biovolume into algal C to obtain an independent measure of cellular algal carbon in periphyton. This information was used in a model relating periphyton C : P ratio to algal cellular carbon, the algal C : P ratio, and the C : P ratio of non-algal organic matter in periphyton. 2. The mean C : Chl ratio of periphyton (405) was relatively high with values in >25% of the samples exceeding 500. On average, 8.4% of total periphyton C was accounted for by C in algal cells. Only 15% of samples were found to have more than 15% periphyton C in cellular algal carbon. Our model showed a nonlinear relationship between periphytic C : P ratios and the C : P ratio of algal cells in the periphyton when non-algal organic matter was present. However, even at relatively low cellular algal C (<10% of total C), algal C : P ratios can strongly affect the C : P ratio of periphyton as a whole (i.e. algal cells plus other organic matter). 3. The high C : Chl ratios and the low biovolume-derived algal C of periphyton samples in our data set indicate that algal cells are typically a minor component of organic carbon in periphyton, However, this minor contribution would not preclude algal cellular stoichiometry from notably influencing periphyton C : P ratios. [source] Neuropsychological correlates of hippocampal and rhinal cortex volumes in patients with mesial temporal sclerosisHIPPOCAMPUS, Issue 8 2003Catherine E. O'Brien Abstract Considerable progress has been made toward understanding the function of the primate rhinal cortex, comprising the entorhinal (ErC) and perirhinal (PrC) cortices. However, translating animal models to human memory has been limited by the technological problems associated with characterizing neural structures in vivo. Functional correlates of hippocampal and rhinal cortex volume changes were examined in a sample of 61 temporal lobe epilepsy patients with mesial temporal sclerosis (MTS; 33 left, 28 right). Patients were administered the Wechsler Adult Intelligence Scale (revised or third edition), the Wechsler Memory Scale (revised or third edition), and a spatial maze task. Neuropsychological data, together with rhinal cortex and hippocampal volumes, collected in our earlier study (O'Brien CE, Bowden SC, Whelan G, Cook MJ, unpublished observations), were analyzed using multiple regression. The only significant predictor of verbal memory function was the difference score between the volume of left hippocampus and the left PrC. Spatial maze scores were predicted by the bilateral sum of ErC volume. The difference score between the left hippocampus and left PrC volumes was the most powerful predictor of verbal episodic memory. Right hippocampal volume was not a significant predictor of nonverbal episodic memory. Verbal and nonverbal semantic memory were not significantly predicted by any combination of rhinal cortex structures. This quantitative study suggests a lateralized or material-specific memory function for the left hippocampus and left PrC, in contrast to the bilateral role of the ErC. The left hippocampus and left PrC appear to act on verbal memory function through an opposing relationship. Finally, differentiation between hippocampal and subhippocampal components in terms of episodic and semantic memory, respectively, could not be supported by the current data. © 2003 Wiley-Liss, Inc. [source] Heart inflow tract of the African lungfish Protopterus dolloiJOURNAL OF MORPHOLOGY, Issue 1 2005José M. Icardo Abstract We report a morphologic study of the heart inflow tract of the African lungfish Protopterus dolloi. Attention was paid to the atrium, the sinus venosus, the pulmonary vein, and the atrioventricular (AV) plug, and to the relationships between all these structures. The atrium is divided caudally into two lobes, has a common part above the sinus venosus, and appears attached to the dorsal wall of the ventricle and outflow tract through connective tissue covered by the visceral pericardium. The pulmonary vein enters the sinus venosus and runs longitudinally toward the AV plug. Then it fuses with the pulmonalis fold and disappears as an anatomic entity. However, the oxygenated blood is directly conveyed into the left atrium by the formation of a pulmonary channel. This channel is formed cranially by the pulmonalis fold, ventrally by the AV plug, and caudally and dorsally by the atrial wall. The pulmonalis fold appears as a wide membranous fold which arises from the left side of the AV plug and extends dorsally to form the roof of the pulmonary channel. The pulmonalis fold also forms the right side of the pulmonary channel and sequesters the upper left corner of the sinus venosus from the main circulatory return. The AV plug is a large structure, firmly attached to the ventricular septum, which contains a hyaline cartilaginous core surrounded by connective tissue. The atrium is partially divided into two chambers by the presence of numerous pectinate muscles extended between the dorsal wall of the atrium and the roof of the pulmonary channel. Thus, partial atrial division is both internal and external, precluding the more complete division seen in amphibians. The present report, our own unpublished observations on other Protopterus, and a survey of the literature indicate that not only the Protopterus, but also other lungfish share many morphologic traits. J. Morphol. 263:30,38, 2005. © 2004 Wiley-Liss, Inc. [source] Seasonal evolution of Titan's dark polar hood: midsummer disappearance observed by the Hubble Space TelescopeMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2006Ralph D. Lorenz ABSTRACT Titan, Saturn's largest moon, has a dense organic-laden atmosphere that displays dramatic seasonal variations in composition and appearance. Here we document the evolution of the dark polar hood, first seen in 1980 by Voyager 1 around the north pole, and report quantitative measurements of the hood's disappearance from the south pole in 2002,2003 using previously unpublished observations with the Hubble Space Telescope Advanced Camera for Surveys (HST/ACS). These data support a model of the hood as a transient structure associated with downwelling during polar winter. [source] Conservation and management of migratory fauna: dams in tropical streams of Puerto RicoAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 7 2006Effie A. Greathouse Abstract 1.Compared with most other tropical regions, Puerto Rico appears to have dammed its running waters decades earlier and to a greater degree. The island has more large dams per unit area than many countries in both tropical and temperate regions (e.g. three times that of the USA), and the peak rate of large dam construction occurred two or three decades before reported peak rates in Latin America, Asia and Africa. 2.Puerto Rico is a potential window into the future of freshwater migratory fauna in tropical regions, given the island's extent and magnitude of dam development and the available scientific information on ecology and management of the island's migratory fauna. 3.The paper reviews the ecology, management and conservation of migratory fauna in relation to dams in Puerto Rico. It includes a synthesis of recent and unpublished observations on upstream effects of large dams on migratory fauna and an analysis of patterns in free crest spillway discharge across Puerto Rican reservoirs. 4.Analyses suggest that large dams with rare spillway discharge cause near, not complete, extirpation of upstream populations of migratory fauna. They also suggest several management and conservation issues in need of further research and consideration, including research on the costs, benefits and effectiveness of simple fish and shrimp passage designs involving simulating spillway discharge. The appropriateness of establishing predatory fish in reservoirs of historically fishless drainages also needs to be considered. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||