<p> The speed of a squirrel-cage induction motor is controlled by varying the supply frequency. The design of an SCH controlled inverter, using gating from a logic unit to give a variable-frequency power-level output, is described.</p> / Thesis / Master of Engineering (MEngr)

No description available.

No description available.

Captive gray squirrels were fed acorns or diets containing commercial tannins to determine the effects of tannins on digestion and detoxification (glucuronidation) activity. In the Acorn experiment, Northern red oak acorns (Quercus rubra), white oak acorns (Q. alba), or rat chow were fed to squirrels. Levels of phenols, condensed tannins, and hydrolyzable tannins were higher in red oak acorns than white oak acorns and were likely responsible for the lower dry matter intake, lower apparent protein digestibility, lower digestible protein and energy intakes, and higher glucuronidation activity observed in squirrels fed red oak acorns. Although apparent protein digestibility and digestible protein intakes were reduced on a white oak acorn diet, this diet did not continuously suppress dry matter intake or stimulate glucuronidation. It appears that gray squirrels may not be able to subsist on red oak acorns alone, but may require other foods to dilute tannin intake and provide additional nutrients. In the Tannin experiment, squirrels were fed rat chow containing no tannins, 4% or 8% tannic acid (hydrolyzable tannin), or 3% or 6% quebracho (condensed tannin). Apparent protein and energy digestibilities of tannic acid-containing diets were lower than the control. These reductions were likely due to the formation of strong complexes between protein and high molecular weight gallotannins. These complexes may have simultaneously protected these gallotannins from hydrolysis and allowed tannic acid to reduce digestive efficiency. Apparent protein and energy digestibilities of quebracho-containing diets were reduced, indicating protein complexing by these nonhydrolyzable tannins. Consistent with the hypothesis that hydrolyzable tannins are more likely to be broken down and absorbed internally than condensed tannins, only the 8% tannic acid diet tended to increase glucuronide excretion. / Master of Science

Master of Science

The principle objectives of the study were; (1) determine accurately the time of breeding, (2) lactation, (3) breeding age, (4) number per litter, and to obtain other miscellaneous data on this popular game animal. Three study areas of varying habitat were chosen. The President’s Hill (17.5 acres) is located on the V. P. I. college campus; Turkey Pen Woods (3.7 acres) is about one-half mile from the President’s Hill and adjacent to a paved highway, and North Crumpacker Woods (6.7 acres) is about 200 yards from Turkey Pen Woods. A special trap was designed, and 74 were constructed for use throughout the study. The Monel, size I, fish tag was used for tagging the ear of the squirrel. The original handling techniques were patterned from those used by previous investigators, however, shortly after the project was begun a squirrel funnel, made of tightly woven sack and one-fourth inch hardware cloth, was constructed and successfully used throughout the remainder of the study. / M.S.

Ένα από τα σύγχρονα προβλήματα που απασχολούν του την κοινωνία είναι το ενεργειακό πρόβλημα, απόρροια της σταδιακής εξάντλησης των συμβατικών πηγών ενέργειας. Μία ιδιαίτερα ελκυστική λύση, αποτελεί η αξιοποίηση των ανανεώσιμων πηγών ενέργειας και ειδικά του ανέμου που παρέχει την αιολική ενέργεια. Η παρούσα διπλωματική εργασία έχει ως θέμα τον έλεγχο ανεμογεννήτριας επαγωγικής μηχανής βραχυκυκλωμένου κλωβού(SCIG) με χρήση ασαφούς λογικής. Ο έλεγχος με ασαφή λογική είναι ταχέως αναπτυσσόμενος καθώς πλησιάζει πολύ στην ανθρώπινη λογική. Βασιστήκαμε πάνω σε ένα ήδη υπάρχον μοντέλο μη-γραμμικού ελέγχου για αυτό το είδος ανεμογεννήτριας και το μετατρέψαμε κατάλληλα για την σταδιακή εφαρμογή της ασαφούς λογικής. Το σύστημα προσομοιώθηκε με τη βοήθεια της εφαρμογής Simulink του λογισμικού Matlab. Τα αποτελέσματα παρουσιάζονται μέσω διαγραμμάτων και εξάγονται τα ανάλογα συμπεράσματα. / One of the current issues that concern the society is the energy problem of the gradual depletion of conventional energy sources. A particularly attractive solution is the exploitation of renewable energy sources, especially wind providing the wind. This thesis will deal with controlling wind turbine induction motor squirrel cage (SCIG) using fuzzy logic. The control with fuzzy logic is rapidly growing as it approaches the human sense. We relied on an existing model of nonlinear control for this type turbine and turned it suitable for the application of fuzzy logic. The system was simulated with the help of application Simulink software Matlab. The results are presented through diagrams and the relative conclusions are extracted.

One of the major environmental concerns in the world is the loss of biological diversity due to anthropogenic activities. Of special concern is the conservation of endemic species that are particularly vulnerable to extinction. The Mearns's squirrel (Tamiasciurus mearnsi) is endemic to the Sierra de San Pedro Mártir, Baja California. Federally listed as threatened in Mexico and as endangered by the International Union for Conservation of Nature (IUCN), little is known about the ecology of this southernmost Tamiasciurus. Interestingly, Mearns's squirrels exhibit deviations from common behaviors observed in other congeners such as lack of leaf nests (dreys) and larderhoards (middens), suggesting potentially unique adaptations. Herein, I reviewed the diversity and conservation status of the arboreal squirrels of Mexico. Using radio-telemetry and satellite imagery, I examined if the lack of dreys and middens may be associated with differences observed in nesting behavior, home-range dynamics, and life-history and behavioral tactics between Mearns's squirrels and other arboreal squirrels.Mexico harbors 14 species of arboreal squirrels, of which four are endemic, with the states of Chiapas and San Luis Potosí possessing the greatest diversity. Unfortunately, high deforestation rates in Mexico, and a dearth of information on their ecology, pose serious threats to the persistence of this squirrel diversity. Mearns's squirrels apparently are obligate secondary cavity-nesters with specific nesting requirements and their population possibly limited by the low occurrence of tree cavities in their habitat. The species seems to have lost the territorial behavior that is characteristic of the genus Tamiasciurus. Home-range dynamics of Mearns's squirrels are similar to nonterritorial Sciurus squirrels. Although reproduction and survival are similar to other Tamiasciurus, the species is heavier and apparently larger while exhibiting important variations in their behavior compared to other congeners. The lack of dreys and middens appears to be associated with the unique tactics adopted by Mearns's squirrels to persist in the Sierra de San Pedro Mártir. The species provides an important opportunity to learn more about geographic variation in nesting behavior and the evolution of territoriality. Large trees and snags that facilitate cavity formation are critical for the conservation of this species.

The grey squirrel (Sciurus carolinensis) has wildtype and melanic (dark) colour morphs. Melanism is associated with variations in the melanocortin-1 receptor (MC1R) gene in a number of species. The MC1R protein is a G-protein coupled receptor, predominantly expressed in melanocytes, where it is a key regulator of pigment production. To investigate the genetic and molecular basis of melanism, the MC1R genes of the wildtype and melanic grey squirrel were sequenced. The wildtype (MC1R-wt) and melanic (MC1RΔ24) variants of the MC1R were then functionally characterised in a cell-based assay. The MC1R gene of the grey squirrel was found to have a 24 base pair (bp) deletion associated with melanism. The MC1R is typically activated by its agonist, the alpha-melanocyte stimulating hormone (α-MSH), which stimulates dark pigment production by raising intracellular cAMP levels. Conversely, the MC1R is inactivated by its inverse agonist, the agouti signalling protein (ASIP), which stops dark pigment production by lowering intracellular cAMP levels. To investigate the effects that the 24 bp deletion have on receptor function, MC1R-wt and MC1RΔ24 genes were transfected into HEK293 cells. Cells expressing either MC1R-wt or MC1RΔ24 were stimulated with α-MSH or ASIP and intracellular cAMP levels were measured. Unstimulated MC1RΔ24 cells showed higher basal activity than the MC1R-wt cells. Both MC1R-wt and MC1RΔ24 cells responded to α-MSH with a concentration-dependent increase in intracellular cAMP. However, while the MC1Rwt cells responded to ASIP with a concentration-dependent decrease in intracellular cAMP, MC1RΔ24 cells responded with an increase in cAMP. Melanism in the grey squirrel is associated with a 24 bp deletion in the MC1R. Cells expressing MC1RΔ24 have higher basal levels of cAMP than MC1R-wt cells. ASIP acts as an inverse agonist to the MC1R-wt but as an agonist to the MC1RΔ24. As MC1RΔ24 cells have higher levels of cAMP, and higher levels of cAMP lead to dark pigment production, the 24 bp deletion is the likely molecular cause of melanism in the grey squirrel.

Immunity and reproduction are important and costly life-history traits and a large part of eco-immunology focuses on trade-offs between investing in reproduction versus immunity. Male Cape ground squirrels (Xerus inauris) are a good organism to test these trade-offs as they invest heavily in sperm competition, evidenced by their large testes, and exhibit alternative reproductive tactics. My research objective was to determine 1) if testosterone suppresses immunity, or if immunity suppresses testosterone, and 2) if alternative reproductive tactics differ in their investments in immunity and reproduction. I found evidence that testosterone was suppressed after an immune challenge, and that manipulatively increased testosterone had no effect on immunity, body condition or parasites. The dispersing tactic males were in worse condition, had higher parasite abundances, but showed no difference in their innate immune ability to non-dispersing males. Males incur increased costs with dispersal and may focus their energy into reproduction instead of immunity. / October 2015