Investigation of primary production in streams and rivers has lagged behind similar investigations in marine and lacustrine environments. Recently, however, Odum (1956) has demonstrated methods that allow the estimation of productivity of most moving waters. For reasons discussed later in this paper, Odum's method is not satisfactory for shallow, very rapid rivers as typified by Logan River. The present investigation then was primarily an exploration of a method possibly applicable to measurement of productivity in shallow rapid rivers. Investigation of phases of the ecology and distribution of the main contributors to primary production, the benthic algae, was a necessary corollary to intelligent measurement of primary production in Logan River. A recent review of the knowledge of ecology of river algae (Blum, 1956) summarizes this topic. Most quantitative investigations of river algae have been directly or indirectly concerned with indices of pollution rather than productivity (Jones, 1951) (Reese, 1937) (Patrick, 1949) (Butcher, 1932, 1940, 1945, and 1947). The growth of algae on slides has been a frequently used method of quantitative study, but it is difficult to relate values attained in this fashion to total productivity or standing crop. Statements concerning algal succession and seasonal variation based on counts of algae growing on glass slides in very rapid water appear questionable.

No description available.

No description available.

Thesis (M. Phil.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

A simple but effective evolutionary algorithm is proposed in this paper for solving complicated optimization problems. The new algorithm presents two hybridization operations incorporated with the conventional genetic algorithm. It takes only 4.1% ~ 4.7% number of function evaluations required by the conventional genetic algorithm to obtain global optima for the benchmark functions tested. Application example is also provided to demonstrate its effectiveness. / Singapore-MIT Alliance (SMA)

This study examined the distinguishing physiological characteristics of the disgust reaction across different domains. According to an evolutionary analysis, disgust is a heterogeneous emotion with features that are specific to three distinct domains: pathogens, sex, and morality. Each domain is predicted to take as input information specific to the adaptive problem it evolved to solve and regulate behavior accordingly. The goal of the present study was to investigate whether there are any adaptive physiological differences associated with the disgust response across domains. Participants were asked to imagine acts that elicit pathogen, sexual, and moral disgust. It was hypothesized that there would be both quantitative and qualitative differences in the physiological reactions based on the appropriate functional outputs for the social (moral and sexual) and nonsocial (pathogen) domains. Individual differences in self-report ratings of disgust as well as the role of religiosity in regulating social disgust were also explored. Results showed significant differences in parasympathetic influences on the heart in response to the sexual stimuli but not to the other domains. Also, the self-report ratings showed that females were more sensitive than males to the sexual stimuli but not to pathogens or moral acts. These results lend further support to the dissociation between the functional domains of disgust. Correlations between levels of religiosity and both subjective ratings of fear towards pathogens and levator labii activation when viewing pathogen stimuli were found. This study provides preliminary evidence of dissociations between different domains of disgust and provides a methodological guideline which can help inform future studies of disgust. Implications of the current findings are discussed, as well as limitations of the current methodology and avenues for further exploration.

Predators use a variety of tactics with which to obtain prey. Here, I describe lingual luring by the mangrove saltmarsh snake (Nerodia clarkii compressicauda), a somewhat unique behavior that involves the use of the tongue to attract fish prey close enough to permit their capture. The lure is characterized by considerable upward curling of the distal portion of the tongue as it protrudes from the mouth. In addition, luring tongue flicks are significantly greater in duration than chemosensory tongue flicks. Both visual and chemical cues are sufficient to stimulate lingual luring, the latter more so than the former. However, both types of cues together have a strong synergistic effect on elicitation of the behavior. Luring behavior presents primarily a visual stimulus, as its frequency was reduced in the dark. Although prey density had no effect on the exhibition of luring by these snakes, prey density did have an effect on their activity level and their choice of foraging sites. N. c. compressicauda was a fairly active forager under the conditions tested in these studies, but its use of a largely sit-and-wait tactic such as predatory luring indicates that this species uses more of a mixed foraging strategy. The foraging behavior of the snakes differed at different levels of habitat structural density, created by using simulated prop roots in a laboratory arena. When no prop-root structure was present, the snakes rarely ventured into open water. However, they spent significantly more time in the water if prop roots were present. Such habitat structure may serve as protection from larger predators that may be impeded by it.

Groundfish distributions were examined in spring 2006 and 2007 in the northern Bering Sea around St. Lawrence Island (SLI). Arctic cod (Boreogadus saida), Bering flounder (Hippoglossoides robustus), and snailfish (Liparidae) were the dominant species south of SLI, whereas Arctic alligatorfish (Ulcina olrikii) and Arctic staghorn sculpin (Gymnocanthus tricuspis), or shorthorn sculpin (Myoxocephalus scorpius) were dominant north of SLI. The results indicate that bottom water (or water column) chlorophyll a and sediment parameters had greater influence on fish distribution in 2006 (cold, pre-bloom conditions), whereas bottom water temperature and sediment grain size were more important in 2007 (warm, bloom conditions) among a total of 14 environmental variables that were analyzed. These findings suggest strong linkages between physical conditions (e.g. water temperature and hydrography as it affects sediment grain size) and biological conditions (e.g. bloom status) in structuring fish communities in the northern Bering Sea. The diet and feeding relationship of six dominant groundfish, specifically Arctic cod, Bering flounder, snailfish, Arctic staghorn sculpin, Arctic alligatorfish, and shorthorn sculpin in the northern Bering Sea were studied using stomach content data in spring 2006 and 2007. All of Bering flounder had empty stomachs. Amphipods were the primary prey in five fish species characterized by feeding narrow niches except snailfish, which consumed a diverse diet. Arctic cod was the only occasional pelagic feeder; all the other fish studied were benthic feeders. High diet overlap was found among some fish species; however, competition was likely reduced by differences in feeding strategies and available food resources. Stable carbon and nitrogen isotopes of groundfish and their potential prey items were measured for trophic relationships and energy flow in the northern Bering Sea in 2006 and 2007. Lipid content impacts on stable isotope analyses were reduced using a mathematical normalization technique using C/N ratios. Values of del13C in fish species showed significantly different between seasons. Trophic levels (TL) were estimated by del15N values of fish and prey species with primary consumer as a baseline indicator. Bivalves and amphipods had the lowest TL values, 2.4 – 3.4, followed by polychaetes (TL = 3.6 – 4.1), and fish (TL = 3.5 – 4.6).

Excess adipose tissue is a risk factor for developing colorectal cancer. However, the present studies demonstrate that lack of adipose-derived factor(s), such as adiponectin, due to the substantial loss of body fat on high dairy calcium diet could increase susceptibility to intestinal tumorigenesis. These studies suggest that a minimum amount or threshold level of adipose tissue may be required to significantly attenuate tumorigenesis. In ApcMin/+ mice, consumption of high dairy calcium diet exhibited markedly reduced adipose tissue and increased tumor number. Our results showed that the high calcium diet reduced fat pad mass by 65%-82% in ApcMin/+ (p<0.03) in comparison with low calcium diet. ApcMin/+ mice on the high calcium diet exhibited an increase in tumor number (76 vs. 29, p=0.009). Moreover, β-catenin gene and cyclin D1 gene expression were significantly induced in intestinal tumor tissue of ApcMin/+ mice on high calcium diet. These effects were not directly resulted from high dietary calcium feeding, but rather associated with loss of body fat mass. Tumor load was not affected by the calcium diet on obese A/yApcMin/+mice despite the fact that high dairy calcium diet produced a substantial loss of body fat, as there was still substantial residual adipose tissue remaining. Our results indicate that protective effects of calcium against colorectal cancer may be least apparent among lean individuals, suggesting that future studies of calcium and colorectal cancer should consider stratification of subjects according to adiposity. In an in vitro environment to determine the adipose-derived factor(s) responsible, we utilized a co-culture system to observe the influence of human adipocytes on the growth of Caco-2, a human colon cancer cell line. We found that human adipocytes substantially suppressed proliferation of Caco-2 by 62.8%. In addition, we reported that human adipocyte conditioned medium inhibited growth of Caco-2 cells by 28.0%-65.6% compare to DMEM. These findings suggest the protective effect of adipocytes on colonic tumorigenesis. To further investigate if adiponecin, a protein hormone secreted from mature adipocytes, is responsible for this inhibitory effect, anti-human adiponectin-neutralizing antibody was added into the human adipocyte conditioned medium (HACM) and to the co-culture system. The antibody blocked the growth-inhibiting effects in both human adipocytes (HA) and HACM. Consistent with this, siRNA-mediated decrease in adiponectin protein in human adipocytes prevented the inhibitory effect of human adipocytes on Caco-2 proliferation. These data demonstrated that human adipocytes inhibit Caco-2 proliferation and that adiponectin is responsible for this effect.

This dissertation investigates variability in the echolocation calls of Brazilian free-tailed bats, Tadarida brasiliensis (Chiroptera: Molossidae), and explores how bats adjust echolocation call structure in response to different behavioral and ecological conditions. Substantial geographic variation exists in the echolocation call structure of T. brasiliensis throughout the species range in the US, but this variation does not correlate with geographic or climatic patterns. Most variation in call structure is due to differences between and within the calls of individuals. When exposed to broadcasts of high frequency insect sounds, free-flying bats consistently responded by shifting call frequencies away from the broadcast frequencies. This response suggests that bats are sensitive to local acoustic interference that decreases the efficiency of echo reception. In another investigation of reactions to interfering sounds, bats responded to echolocation playbacks by rapidly shifting their call frequencies away from playback frequencies, indicating that a jamming avoidance response was occurring. Bats more frequently shifted their calls upwards to higher frequencies, which may be due to maximal jamming power of the lower frequency portion of echolocation calls. Flexibility in their echolocation calls also was evident in calls produced by T. brasiliensis while emerging from roosts in a tight column formation. Bats emitted two distinct call types during emergence, sweep and hook calls, which were substantially different from foraging calls. Call structure differed between roosts, which may be related to differences in the spacing of bats within emergence columns. In a final experiment, it was found that bat activity was substantially greater in response to echolocation playbacks that contained feeding buzz calls compared to broadcasts that did not contain these signals, indicating that bats eavesdrop on the echolocation calls of conspecifics. Overall, this study documents the highly flexible nature of echolocation in Brazilian free-tailed bats and demonstrates that bats respond acoustically to behavioral and ecological influences.