23,628 research outputs found
Effect of Varying Dietary Selenium Levels on Tissue Composition, Blood Composition and Performance of Growing Swine Fed Seleniferous Grains
It is established that selenium is an essential micronutrient as well as a natural toxicant for domestic livestock. However, reports of selenium toxicosis in swine are limited and not well documented. The level at which selenium becomes toxic to swine is thought to be about 8 ppm. This value was derived from the initial selenium research of the 1930\u27s, with considerable extrapolation from other species used in this determination. Since that time, diet composition has become much more complex, nutrient level of diets has increased and feed additives are commonly used. It is not known what effect these factors or other nutritional interrelationships may have on the level at which selenium becomes toxic. Due to the variability of selenium content in feedstuffs and because selenium is now approved as a feed additive, it is important to better define the level at which selenium becomes toxic to swine. This research was conducted to determine the effect of varying dietary selenium levels on tissue and blood composition and performance of growing swine fed seleniferous grains
Reconceptualizing the Human Social Niche: How It Came to Exist and How It Is Changing
In this paper we present a reconceptualization of the social dimension of the human niche and the evolutionary process that brought it into existence. We agree with many other evolutionary approaches that a key aspect of the human niche is a social environment consisting primarily of cooperating and altruistic individuals, not a Hobbesian social environment of “war of all against all.” However, in contrast to the conception of this social environment as consisting of individuals who, in Boyd and Richerson’s words, “cooperate with large groups of unrelated individuals,” we propose that it is more accurately described as consisting of cooperating individuals who currently are often nonkin but who, until relatively recently in human existence, were primarily, and in many cases almost exclusively, kin. In contrast to the conception of this social environment coming into existence by way of a process of selection within and between groups, we propose that it is the result of selection operating on traditions originated by ancestors and transmitted to their descendants. We use our fieldwork in three areas of the world (New Guinea, Ecuador, and Canada) to illustrate this process and how current social environments can be roughly placed on a continuum from traditional to nontraditional
Precision metering of microliter volumes of biological fluids in micro-gravity
Concepts were demonstrated and investigated for transferring accurately known and reproducible microliter volumes of biological fluids from sample container onto dry chemistry slides in microgravity environment. Specific liquid transfer tip designs were compared. Information was obtained for design of a liquid sample handling system to enable clinical chemical analysis in microgravity. Disposable pipet tips and pipet devices that were designed to transfer microliter volumes of biological fluid from a (test tube) sample container in 1-G environment were used during microgravity periods of parabolic trajectories of the KC-135 aircraft. The transfer process was recorded using charge coupled device camera and video cassette equipment. Metering behavior of water, a synthetic aqueous protein solution, and anticoagulated human blood was compared. Transfer of these liquids to 2 substrate materials representative of rapidly wettable and slowly wettable dry chemistry slide surface was compared
The QUIC Fix for Optimal Video Streaming
Within a few years of its introduction, QUIC has gained traction: a significant chunk of traffic is now delivered over QUIC. The networking community is actively engaged in debating the fairness, performance, and applicability of QUIC for various use cases, but these debates are centered around a narrow, common theme: how does the new reliable transport built on top of UDP fare in different scenarios? Support for unreliable delivery in QUIC remains largely unexplored. The option for delivering content unreliably, as in a best-effort model, deserves the QUIC designers' and community's attention. We propose extending QUIC to support unreliable streams and present a simple approach for implementation. We discuss a simple use case of video streaming---an application that dominates the overall Internet traffic---that can leverage the unreliable streams and potentially bring immense benefits to network operators and content providers. To this end, we present a prototype implementation that, by using both the reliable and unreliable streams in QUIC, outperforms both TCP and QUIC in our evaluations
WEFES - Web explorer of forest ecosystems services under climate change
PosterClimate change will change the dynamics of forest environmental services. All the change complexity involved is difficult to visualize under an easy and accessible information tool capable to integrate several services that forests can provide.
A preliminary Web-Explorer of Forest Ecosystems Services was developed for New Zealand where forest managers and the general public can observe what are the predictions of the different forest environmental services under current and future climate for each location in the territory. Carbon storage, soil erosion, biodiversity, nitrate leaching, water balance are the preliminary forest environmental services envisaged.
The tool uses a mix of programming languages and techniques (HTML, Javascript, PHP, and Ajax) as well as the GoogleMaps© application programming interface to interact with New Zealand online-stored geographical information to supply different models´ needs. A score system is calculated for the user reference where tradeoffs can be observed by changing the climate variables in the models.
The tool (see link below) is under development and expecting “expressions of interest” for further improvement but already enabled a good interaction between different scientific background as well as interest from private forest organizations.
Tool link: http://home.isa.utl.pt/~joaopalma/projects/tranzfor/wefesTRANZFOR - SCION - ISA/UTL - MORST - FFR - FCT/MCTE
TGRS Observations of Positron Annihilation in Classical Novae
The TGRS experiment on board the Wind spacecraft has many advantages as a sky
monitor --- broad field of view (~2 pi) centered on the south ecliptic pole),
long life (1994-present), and stable low background and continuous coverage due
to Wind's high altitude high eccentricity orbit. The Ge detector has sufficient
energy resolution (3-4 keV at 511 keV) to resolve a cosmic positron
annihilation line from the strong background annihilation line from beta-decays
induced by cosmic ray impacts on the instrument, if the cosmic line is
Doppler-shifted by this amount. Such lines (blueshifted) are predicted from
nucleosynthesis in classical novae. We have searched the entire TGRS database
for 1995-1997 for this line, with negative results. In principle such a search
could yield an unbiased upper limit on the highly-uncertain Galactic nova rate.
We carefully examined the times around the known nova events during this
period, also with negative results. The upper limit on the nova line flux in a
6-hr interval is typically <3.8 E-3 photon/(cm2 s) at 4.6 sigma. We performed
the same analysis for times around the outburst of Nova Vel 1999, obtaining a
worse limit due to recent degradation of the detector response caused by cosmic
ray induced damage.Comment: 5 pp. inc. 3 figs. Proc. 5th Compton Symposium (AIP Conf. Series),
ed. M. McConnell, in pres
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