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Clustering properties and halo occupation of Lyman-break galaxies at z ~ 4

  • Park, Jaehong;Kim, Han-Seek;Wyithe, Stuart B.;Lacey, Cedric G.;Baugh, Carlton M.
    • 천문학회보
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    • 제40권1호
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    • pp.59.3-60
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    • 2015
  • We investigate the clustering properties of Lyman-break galaxies (LBGs) at z ~ 4. Using the hierarchical galaxy formation model GALFORM, we predict the angular correlation function (ACF) of LBGs and compare this with the measured ACF from combined survey fields consisting of the Hubble eXtreme Deep Field (XDF) and CANDELS. We find that the predicted ACF is in a good agreement with the measured ACFs. However, when we divide the model LBGs into bright and faint subset, the predicted ACFs are less consistent with observations. We quantify the dependence of clustering on luminosity and show that the fraction of satellite LBGs is important for determining the amplitude of ACF at small scales. We find that central LBGs predominantly reside in ${\sim}10^{11}h^{-1}M_{solar}$ haloes and satellites reside in haloes of mass ${\sim}10^{12}-10^{13}h^{-1}M_{solar}$. The model predicts fewer bright satellite LBGs than is inferred from the observation. LBGs in the tails of the redshift distribution contribute significant additional clustering signal, especially on small scales. This spurious clustering may affect the interpretation of the halo occupation distribution, including the minimum halo mass and abundance of satellite LBGs.

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UREA-MOLASSES AND COTTONSEED-MOLASSES SUPPLEMENTS FOR DAIRY GOATS

  • Sarwiyono, Sarwiyono;Mcllroy, B.K.M.H.;Dixon, R.M.;Holme, J.H.G.
    • Asian-Australasian Journal of Animal Sciences
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    • 제5권4호
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    • pp.653-658
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    • 1992
  • Crossbred dairy does were fed a roughage diet (IVOMD 56%, N 2.27%) ad libitum, and supplemented with urea-molasses (3% W : W) (UM) at levels on an air dry basis of 1.5% or 3% of liveweight or an iso-energetic, iso-nitrogenous mixture of cottonseed meal and molasses (25 : 75 w : w) (CM). Eight does, four lower-producers and four higher-producers (1.9 and 2.5 kg/day respectively in week 7 of lactation) arranged in two Latin Squares, received each of the four diets for three weeks. Dry matter, digestible organic matter and N intakes were higher for high-producers and high levels of supplement but did not differ between nitrogen sources. Milk production was higher by high-producers; interactions were significant between level of supplement and production group and between level of supplement and N-source, with maximum production by high producers on high levels of CM. The main effects of level of supplement were only significant for production or composition. and total solids; N-source did not have significant effects on liveweight, milk production or composition. We conclude that does of moderate capacity for milk production, receiving a diet of two-thirds moderate quality roughage, one third urea-molasses, will not respond to increased level of supplementation or to replacement of urea with cottonseed meal.

Lablab purpureus SEED AS A SUPPLEMENT FOR GOATS FED LOW QUALITY ROUGHAGE

  • Ismartoyo, I.;Dixon, R.M.;Slocombe, R.F.;Holmes, J.H.G.
    • Asian-Australasian Journal of Animal Sciences
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    • 제6권4호
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    • pp.515-519
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    • 1993
  • Young goats were fed low quality roughage ad libitum and supplements of insect-damaged Lablab purpureus (var. Highworth) seed fed at approximately 3, 6 or 12 g/kg liveweight (LW), or sweet lupin seed (Lupinus angustifolius var. Uniharvest) fed at 12 g/kg LW. Roughage intake was not changed by 3 or 6 g/kg LW levels of Lablab or by 12 g/kg LW lupin supplement, but was reduced (p<0.05) by 35% by 12 g/kg LW Lablab supplement. Organic matter (OM) digestibility was increased by all supplements, and digestible OM intake was increased by the 6 g/kg LW Lablab and 12 g/kg LW lupin supplements. LW gain and feed conversion ratio were not changed by 3 or 6 g/kg LW Lablab or the 12 g/kg LW lupin, but were reduced (p<0.05) by 12 g/kg LW Lablab supplement. It was concluded that young goats could efficiently utilize supplements of Lablab purpureus seed fed at levels of up to 6 g/kg LW. However, when 12 g/kg of the Lablab seed was fed, poor performance suggested that the goats were adversely affected by anti-nutritional factors which were not neutralized by rumen fermentation.

Earthquake ductility and overstrength in residential structures

  • Gad, E.F.;Chandler, A.M.;Duffield, C.F.;Hutchinson, G.L.
    • Structural Engineering and Mechanics
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    • 제8권4호
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    • pp.361-382
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    • 1999
  • This paper reviews aspects of current design procedures for seismic design of structures, and specifically examines their relevance to the design of light framed residential buildings under earthquake loading. The significance of the various structural contributions made by the components of cold formed steel framed residential structures subjected to earthquake induced loadings has been investigated. This is a common form of residential construction worldwide. Particular attention is given to aspects related to ductility and overstrength, the latter arising principally from the contributions of the designated "non-structural" components. Based on both analytical and experimental data obtained from research investigations on steel framed residential structures, typical ranges of the ductility reduction factor and overstrength ratios are determined. It is concluded that the latter parameter has a very significant influence on the seismic design of such structures. Although the numerical ranges for the inelastic seismic parameters given in this paper were obtained for Australian houses, the concepts and the highlighted aspects of seismic design methodology are more widely applicable.

The Effects of Water Deprivation on Cerebrospinal Fluid Constituents During Feeding in Sheep

  • Sunagawa, Katsunori;Weisinger, Richard S.;McKinley, Michael J.;Purcell, Brett S.;Thomson, Craig;Burns, Peta L.
    • Asian-Australasian Journal of Animal Sciences
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    • 제14권4호
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    • pp.467-473
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    • 2001
  • The internal humoral factors in the central regulation of dry feed intake during water deprivation in sheep were investigated by measurement of cerebrospinal fluid (CSF) constituents. Five animals were fed dried alfalfa chaff for 2 hours once a day. Sheep in the water deprivation treatment were deprived of water for 28 hours, while the sheep in the control treatment were given free access to water. During the first hour of the 2 hour feeding period, a rapid reduction in blood volume occured in both treatments (water deprivation and free access to water). The CSF concentrations of Na, Cl and osmolality during the second hour of the 2 hour feeding period in both treatments were greater (p<0.01) than those during the first hour. The drinking behaviors in sheep were concentrated during the second hour of the 2 hour feeding period in periods of free access to water. Water intake during feeding in periods of free access to water was 1110 ml/2 h. The levels of increase in CSF osmolality with feeding during water deprivation were greater (p<0.01) than during periods of free access to water. The changes in CSF osmolality with feeding during water deprivation produced more vigorous thirst sensations in the brain compared to during periods of free access to water. The eating rates for the first hour of the allotted 2 hour feeding period were the same under both treatments. However, the eating rates for the second hour during water deprivation periods decreased significantly (p<0.05) compared to those during periods of free access to water. The decreased eating rates for the second hour during water deprivation may be due to the vigorous thirst sensations produced in the brain. The results suggest that the increase in CSF osmolality with feeding during water deprivation acts as a thirst and satiety factor in brain mechanisms controlling feeding to decrease dry feed intake in water-deprived sheep.