![]() ![]() Their small size, high wing-beat frequencies, high metabolic rates and reliance upon simple sugars to supply most of their daily energy needs ( Norberg et al., 1993 Voigt and Speakman, 2007 Winter and von Helversen, 1998 Winter and von Helversen, 2001), led us to hypothesize that, like hummingbirds, they are able to directly fuel their exercising muscles using recently ingested sugar. Given their nectarivorous diet and phylogenetic status, it is of interest to determine the extent to which nectarivorous bats rely on recently ingested sugar to fuel their energetically expensive flight. In addition,capacities for the assimilation, transport and oxidation of dietary fuels are also limited in humans only about 25–30% of energy expenditure can be supported by sugar ingested shortly before (or during) exercise. This is thought to be due to their limited capacities to transport and metabolize exogenous fuels (glucose and fatty acids) from the blood ( Weber et al., 1996 Weber, 1988). In contrast, at moderate to high exercise intensities, humans and other mammals rely heavily on endogenous fuels (glycogen and triglyceride) stored in their locomotory muscles. Hover-feeding hummingbirds are almost exclusively able to fuel their highly aerobic flight muscles using recently ingested sugar( Welch et al., 2006 Welch and Suarez, 2007). During hovering, >90% of whole-body metabolic rate (rate of oxygen consumption, V̇ O 2)is due to exercising flight muscles( Suarez, 1992 Taylor, 1987). Hovering flight is energetically costly hovering hummingbirds achieve some of the highest known mass-specific metabolic rates among vertebrates ( Suarez, 1992). In evolving to be small and to hover while feeding on floral nectar,neotropical Glossophagine bats have undergone evolutionary convergence with hummingbirds. These results support the suggestion that convergent evolution of physiological and biochemical traits has occurred among hovering nectarivorous animals,rendering them capable of a process analogous to aerial refueling in aircraft. Similar experiments performed on Anna's ( Calypte anna) and rufous ( Selasphorus rufus) hummingbirds show that they use recently ingested sugars to support ∼95% of hovering metabolism. Among vertebrate animals, only hummingbirds exceed the capacity of these nectarivorous bats to fuel exercise with dietary sucrose. measurement of rates of O 2 consumption and CO 2 production, in combination with carbon stable isotope techniques, we found that nectarivorous bats Glossophaga soricina use recently ingested sugars to provide ∼78%of the fuel required for oxidative metabolism during their energetically expensive hovering flight. Humans,for example, can only fuel about 30%, at most, of exercise metabolism with dietary sugar. Usually commercial software or games are produced for sale or to serve a commercial purpose.It is thought that the capacity of mammals to directly supply the energetic needs of exercising muscles using recently ingested fuels is limited. Even though, most trial software products are only time-limited some also have feature limitations. ![]() After that trial period (usually 15 to 90 days) the user can decide whether to buy the software or not. Trial software allows the user to evaluate the software for a limited amount of time. Demos are usually not time-limited (like Trial software) but the functionality is limited. In some cases, all the functionality is disabled until the license is purchased. Demoĭemo programs have a limited functionality for free, but charge for an advanced set of features or for the removal of advertisements from the program's interfaces. In some cases, ads may be show to the users. ![]() Basically, a product is offered Free to Play (Freemium) and the user can decide if he wants to pay the money (Premium) for additional features, services, virtual or physical goods that expand the functionality of the game. This license is commonly used for video games and it allows users to download and play the game for free. There are many different open source licenses but they all must comply with the Open Source Definition - in brief: the software can be freely used, modified and shared. Programs released under this license can be used at no cost for both personal and commercial purposes. ![]() Open Source software is software with source code that anyone can inspect, modify or enhance. Freeware products can be used free of charge for both personal and professional (commercial use). Freeware programs can be downloaded used free of charge and without any time limitations. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |