3,224 research outputs found
Technical note: Whole-pen assessments of nutrient excretion and digestibility from dairy replacement heifers housed in sand-bedded freestalls
Our objectives were to describe and test refined procedures for quantifying excreta produced from whole pens of dairy heifers. Previous research efforts attempting to make whole-pen measurements of excreta output have been complicated by the use of organic bedding, which requires cumbersome analytical techniques to quantify excreta apart from the bedding. Research pens equipped with sand-bedded freestalls offer a unique opportunity for refinement of whole-pen fecal collection methods, primarily because sand-bedded freestall systems contain no organic bedding; therefore, concentrations of ash within the manure, sand, and feces can be used to correct for contamination of manure by sand bedding. This study was conducted on a subset of heifers from a larger production-scale feeding trial evaluating ensiled eastern gamagrass [Tripsacum dactyloides (L.) L.] haylage (EGG) that was incorporated into a corn silage/alfalfa haylage-based blended diet at rates of 0, 9.1, 18.3, or 27.4% of total DM. The diet without EGG also was offered on a limited basis. Eighty Holstein dairy heifers were blocked (heavy weight, 424 ± 15.9 kg; light weight, 324 ± 22.4 kg) and then assigned to 10 individual pens containing 8 heifers/pen. One pen per block was assigned to each of the 5 research diets, and whole-pen fecal collections were conducted twice for each pen. Grab fecal samples also were gathered from individual heifers within each pen, and subsequent analysis of these whole-pen composites allowed reasonable estimates of OM and NDF excreta output. Under the conditions of our experimental design, pooled SEM for the excreta DM, OM, NDF, and NDF (ash corrected) output were 0.113, 0.085, 0.093, and 0.075 kg· heifer â1·dâ1, respectively. For DM excretion, this represented about one-third of the SEM reported for previous whole-pen collections from bedded- pack housing systems. Subsequent calculations of apparent DM and OM digestibilities indicated that the technique was sensitive, and linear trends (P †0.027) associated with the inclusion rates of EGG within the diet were detected. This technique allows estimation of apparent diet digestibilities on multiple animals simultaneously, thereby mitigating the need for isolating individual animals to obtain digestibility coefficients. The approach appears viable but requires hand labor for collections of multiple pens and thorough mixing of large volumes of manure as well as analytical corrections for sand ingested by lounging heifers
Resistance and resilience of socialâecological systems to recurrent typhoon disturbance on a subtropical island: Taiwan
Tropical cyclones (TCs) have major effects on ecological and social systems. However, studies integrating the effects of TCs on both social and ecological systems are rare, especially in the northwest Pacific, where the frequency of TCs (locally named typhoons) is the highest in the world. We synthesized studies of effects of recurrent typhoons on social and ecological systems in Taiwan over the last several decades. Many responses to TCs are comparable between social and ecological systems. High forest ecosystem resistance, evident from tree mortality below 2% even following multiple strong typhoons, is comparable with resistance of social systems, including the only 4% destruction of river embankments following a typhoon that brought nearly 3000 mm rainfall in three days. High resilience as reflected by quick returns of leaf area index, mostly in one year, and streamwater chemistry, one to several weeks to preâtyphoon levels of ecosystems, are comparable to quick repair of the power grid within one to several days and returns of vegetable price within several weeks to preâtyphoon levels of the social systems. Landslides associated with intense typhoons have buried mountain villages and transported large quantities of woody debris to the coast, affecting the coastal plains and reefs, illustrating a ridgeâtoâreef link between ecological and societal systems. Metrics of both social and ecological function showed large fluctuations in response to typhoons but quickly returned to preâdisturbance levels, except when multiple intense typhoons occurred within a single season. Our synthesis illustrates that the socialâecological systems in Taiwan are highly dynamic and responsive to frequent typhoon disturbance, with extraordinarily high resistance and resilience. For ecosystems, the efficient responsiveness results from the selective force of TCs on ecosystem structure and processes. For social systems, it is the result of the effects of TCs on planning and decision making by individuals (e.g., farmers), management sectors, and ultimately the government. In regions with frequent TCs, the socialâecological systems are inevitably highly dynamic and rapid responses are fundamental to system resistance and resilience which in turn is key to maintaining structure and function of the socialâecological systems
Course of pattern-reversed visual evoked cortical potentials in 30 eyes after bony orbital decompression in dysthyroid optic neuropathy
Cue-induced smoking urges deplete cigarette smokers' self-control resources
Background: Exposure to smoking-related cues leads to increased urge to smoke in regular cigarette smokers and resisting these urges requires considerable self-control. Purpose: Adopting a resource depletion model, two studies tested the hypothesis that resisting smoking urges depletes self-control resources. Methods: Adopting a within-participants randomized cross-over design, participants (study 1, Nâ=â19; study 2, Nâ=â32) were exposed to smoking-related (study 1: smoking images; study 2: cigarette cue-exposure task) and neutral (study 1: neutral images; study 2: drinking-straw task) cues with presentation order randomized. After each cue set, participants completed self-control tasks (study 1: handgrip task; study 2: handgrip and Stroop tasks), performance on which constituted dependent measures of self-control.Results: Self-control task performance was significantly impaired when exposed to smoking-related cues compared to neutral cues. No significant presentation-order effects, or interaction effects between stimulus and presentation order, were found. Conclusions: Findings corroborate our hypothesis that resisting smoking urges depletes cigarette smokersâ self-control resources and suggests that self-control capacity is governed by a limited resource
The origin of HIMU in the SW Pacific : evidence from intraplate volcanism in southern New Zealand and subantarctic islands
Author Posting. © The Author, 2006. This is the author's version of the work. It is posted here by permission of Oxford University Press for personal use, not for redistribution. The definitive version was published in Journal of Petrology 27 (2006): 1673-1704, doi:10.1093/petrology/egl024.This paper presents field, geochemical and isotopic (Sr, Nd, Pb) results on basalts from the Antipodes, Campbell and Chatham Islands, New Zealand. New 40Ar/39Ar age determinations along with previous K-Ar dates reveal three major episodes of volcanic activity on Chatham Island (85-82, 41-35, ~5 Ma). Chatham and Antipodes samples comprise basanite, alkali and transitional basalts that have HIMU-like isotopic (206Pb/204Pb >20.3-20.8, 87Sr/86Sr 0.5128) and trace element affinities (Ce/Pb 28-36, Nb/U 34-66, Ba/Nb 4-7). The geochemistry of transitional to Q-normative samples from Campbell Island is explained by interaction with continental crust. The volcanism is part of a long-lived (~100 Myr), low-volume, diffuse alkaline magmatic province that includes deposits on the North and South Islands as well as portions of West Antarctica and SE Australia. All of the continental areas were juxtaposed on the eastern margin of Gondwanaland at >83 Ma. A ubiquitous feature of mafic alkaline rocks from this region is their depletion in K and Pb relative to other highly incompatible elements when normalized to primitive mantle values. The inversion of trace element data indicates enriched mantle sources that contain variable proportions of hydrous minerals. We propose that the mantle sources represent continental lithosphere that host amphibole/phlogopite-rich veins formed by plume and/or subduction related metasomatism between 500 and 100 Ma. The strong HIMU signature (206Pb/204Pb >20.5) is considered to be an in-grown feature generated by partial-dehydration and loss of hydrophile elements (Pb, Rb, K) relative to more magmaphile elements (Th, U, Sr) during short-term storage at the base of the lithosphere.This study was supported by National Science Foundation Grants OPP-9419686 and OPP-0003702 awarded to KSP
Towards a realistic microscopic description of highway traffic
Simple cellular automata models are able to reproduce the basic properties of
highway traffic. The comparison with empirical data for microscopic quantities
requires a more detailed description of the elementary dynamics. Based on
existing cellular automata models we propose an improved discrete model
incorporating anticipation effects, reduced acceleration capabilities and an
enhanced interaction horizon for braking. The modified model is able to
reproduce the three phases (free-flow, synchronized, and stop-and-go) observed
in real traffic. Furthermore we find a good agreement with detailed empirical
single-vehicle data in all phases.Comment: 7 pages, 7 figure
Sex matters: retrospective data collection on the date of commencement of ART for HIV-positive women and men in the German KompNet cohort (1991-2009)
Renormalization Group Approach to Oscillator Synchronization
We develop a renormalization group method to investigate synchronization
clusters in a one-dimensional chain of nearest-neighbor coupled phase
oscillators. The method is best suited for chains with strong disorder in the
intrinsic frequencies and coupling strengths. The results are compared with
numerical simulations of the chain dynamics and good agreement in several
characteristics is found. We apply the renormalization group and simulations to
Lorentzian distributions of intrinsic frequencies and couplings and investigate
the statistics of the resultant cluster sizes and frequencies, as well as the
dependence of the characteristic cluster length upon parameters of these
Lorentzian distributions.Comment: 13 pages, 7 figures: 8 figure files in *.eps format and one *.tex
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