948 resultados para Brown, Ronald Harmon.


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Multiple recent studies provide evidence that both human and nonhuman primates possess motor planning abilities. I tested for the demonstration of motor planning in two previously untested primate species through two experiments. In the first experiment, I compared the extent to which squirrel monkeys (Saimiri sciureus) and brown capuchins (Cebus apella) plan their movements in a grasping task. Individuals were presented with an inverted cup that required being turned and held upright in order to extract a food reward from the inside of the cup. This task was most efficiently solved by using an initially awkward inverted grasp that affords a comfortable hand and arm orientation at the end of the movement (known as end-state comfort). While certain individuals from both species exhibited end-state comfort, many of the capuchins never demonstrated this type of motor planning. Furthermore, the squirrel monkeys used the efficient grasp significantly more than the capuchins. In the second experiment, I presented the capuchins with another grasping task to test if they would express motor planning abilities in a different context. Here, the capuchins were offered a dowel that was baited on either the left or right end. A radial grasp with the thumb pointing towards the baited end was considered to be the most efficient grasp because it afforded a comfortable final position. The capuchins switched hands and used an overhand radial grasp on the dowel significantly more often than not, thus demonstrating motor planning in this task. The grasps typically utilized by these two closely related species differ considerably in that capuchins are capable of exercising precision grips, whereas squirrel monkeys are limited to whole-handed power grips. Moreover, unlike capuchins, squirrel monkeys are not particularly dexterous nor are they capable of precise manipulative actions. It is therefore more beneficial for squirrel monkeys to plan their movements efficiently because they are less capable of compensating for inappropriate initial grasps. Due to the appreciable variability in the expression of motor planning skills across species, I proposed that morphological constraints might explain the observed discrepancies in movement planning among different primate species.

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Self-control allows an individual to obtain a more preferred outcome by forgoing an immediate interest. Self-control is an advanced cognitive process because it involves the ability to weigh the costs and benefits of impulsive versus restrained behavior, determine the consequences of such behavior, and make decisions based on the most advantageous course of action. Self-control has been thoroughly explored in Old World primates, but less so in New World monkeys. There are many ways to test self-control abilities in non-human primates, including exchange tasks in which an animal must forgo an immediate, less preferred reward to receive a delayed, more preferred reward. I examined the self-control abilities of six capuchin monkeys using a task in which a monkey was given a less preferred food and was required to wait a delay interval to trade the fully intact less preferred food for a qualitatively higher, more preferred food. Partially eaten pieces of the less preferred food were not rewarded, and delay intervals increased on an individual basis based on performance. All six monkeys were successful in inhibiting impulsivity and trading a less preferred food for a more preferred food at the end of a delay interval. The maximum duration each subject postponed gratification instead of responding impulsively was considered their delay tolerance. This study was the first to show that monkeys could inhibit impulsivity in a delay of gratification food exchange task in which the immediate and delayed food options differed qualitatively and a partially eaten less preferred food was not rewarded with the more preferred food at the end of a delay interval. These results show that New World monkeys possess advanced cognitive abilities similar to those of Old World primates.

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The emerging disease White-Nose Syndrome in hibernating bat populations across the United States has increased the need to understand the physiological benefits and consequences of hibernation and the effects on immunological responsiveness. Hibernation has been well-documented in many mammalian species, yet few studies have examined hibernation immunology in bats, particularly with respect to normal immunological patterns. In order to characterize the levels of circulating leukocytes and plasma immunoglobulins in euthermic and hibernating female big brown bats (Eptesicus fuscus), blood smear differential leukocyte counts and total immunoglobulin assays were performed for each group using blood samples from the active and hibernation seasons. Hibernation patterns – torpor and arousals from torpor – were determined by placing temperature-sensitive dataloggers on the backs of bats assigned to the hibernating group during the hibernation season. Data indicate that the ratio of circulating neutrophils to lymphocytes is lower in bats assigned to the euthermic group during the hibernation season than in bats assigned to the hibernation group during the hibernation period, but that relative immunoglobulin levels do not differ during the hibernation season, regardless of whether bats were active or hibernating. Neither bats assigned to the hibernation group nor bats assigned to the euthermic group demonstrate a significant change in the ratio of circulating neutrophils and lymphocytes between their active and hibernating seasons. Bats assigned to the hibernation group were also observed to arouse from torpor somewhat synchronously. These results suggest that innate and adaptive cell levels are maintained, at best, in hibernating bats that are not immunologically challenged and that bats that remain euthermic during the hibernation season are able to continually regulate their levels of neutrophils and lymphocytes and therefore their innate and adaptive immune system responses.

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The breeding program for beef cattle in Japan has changed dramatically over 4 decades. Visual judging was done initially, but progeny testing in test stations began in 1968. In the 1980s, the genetic evaluation program using field records, so-called on-farm progeny testing, was first adopted in Oita, Hyogo, and Kumamoto prefectures. In this study, genetic trends for carcass traits in these 3 Wagyu populations were estimated, and genetic gains per year were compared among the 3 different beef cattle breeding programs. The field carcass records used were collected between 1988 and 2003. The traits analyzed were carcass weight, LM area, rib thickness, s.c. fat thickness, and beef marbling standard number. The average breeding values of reproducing dams born the same year were used to estimate the genetic trends for the carcass traits. For comparison of the 3 breeding programs, birth years of the dams were divided into 3 periods reflecting each program. Positive genetic trends for beef marbling standard number were clearly shown in all populations. The genetic gains per year for all carcass traits were significantly enhanced by adopting the on-farm progeny testing program. These results indicate that the on-farm progeny testing program with BLUP is a very powerful approach for genetic improvement of carcass traits in Japanese Wagyu beef cattle.

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A heifer with developmental skeletal disorder was presented to the ruminant clinic of the University of Berne. Abnormal long bone growth and a wobbling gait were the main clinical signs. All long bones were examined radiologically, several parameters of body size were measured and the results were compared to the measurements of a healthy control animal. Haematology and blood chemistry were normal. Based on the poor prognosis the animal was slaughtered. The final diagnosis of hyena disease was based on the characteristic growth disturbances in the caudal parts of the body, giving the animal a hyena-like appearance. For the first time a case of hyena disease is reported in Switzerland.

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This field study examined the vitellogenin (VTG) biomarker response under conditions of low and fluctuating activities of environmental estrogenicity. The present study was performed on immature brown trout (Salmo trutta) exposed to the small river Luetzelmurg, which is located in the prealpine Swiss midland region and receives effluents from a single sewage treatment plant (STP). To understand better factors influencing the relationship between estrogenic exposure and VTG induction, we compared VTG levels in caged (stationary) and feral (free-ranging) fish, VTG levels in fish from up- and downstream of the STP, and two different methods for quantifying VTG (enzyme-linked immunosorbent assay vs real-time reverse transcription-polymerase chain reaction), and we used passive samplers (polar organic chemical integrative sampler [POCIS]) to integrate the variable, bioaccumulative estrogenic load in the river water over time. The POCIS from the downstream site contained approximately 20-fold higher levels of bioassay-derived estrogen equivalents than the POCIS from the upstream site. In feral fish, this site difference in estrogenic exposure was reflected in VTG protein levels but not in VTG mRNA. In contrast, in caged fish, the site difference was evident only for VTG mRNA but not for VTG protein. Thus, the outcome of VTG biomarker measurements varied with the analytical detection method (protein vs mRNA) and with the exposure modus (caged vs feral). Our findings suggest that for environmental situations with low and variable estrogenic contamination, a multiple-assessment approach may be necessary for the assessment of estrogenic exposure in fish.

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The Salt Chuck, Rush and Brown, and adjacent mines and claims form an area of approximately 15 square miles near the head of Kasaan Bay about 10 miles northwest of the village of Kasaan on Prince of Wales Island in southeastern Alaska. It is an area of moderate relief in which the hills rise from the water’s edge to heights of some 500 feet. Most of the area is covered with dense vegetation and muskeg.

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Arachnomelia in Brown Swiss cattle is a monogenic autosomal recessive inherited congenital disorder of the skeletal system giving affected calves a spidery look (OMIA ID 000059). Over a period of 20 years 15 cases were sampled in the Swiss and Italian Brown cattle population. Pedigree data revealed that all affected individuals trace back to a single acknowledged carrier founder sire. A genome scan using 240 microsatellites spanning the 29 bovine autosomes showed homozygosity at three adjacent microsatellite markers on bovine Chr 5 in all cases. Linkage analysis confirmed the localization of the arachnomelia mutation in the region of the marker ETH10. Fine-mapping and haplotype analysis using a total of 34 markers in this region refined the critical region of the arachnomelia locus to a 7.19-Mb interval on bovine Chr 5. The disease-associated IBD haplotype was shared by 36 proven carrier animals and allows marker-assisted selection. As the corresponding human and mouse chromosome segments do not contain any clear functional candidate genes for this disorder, the mutation causing arachnomelia in the Brown Swiss cattle might help to identify an unknown gene in bone development.