717 research outputs found
Uterine Capacity and Ovulation Rate in Mice Selected 21 Generations on Alternative Criteria to Increase Litter Size
After 21 generations of selection for alternative criteria to change litter size in mice, responses in uterine capacity and ovulation rate were evaluated. Females from Generations 22 and 23 were sampled from 12 lines, representing three replicates of four selection criteria: LS = direct selection on litter size; M = selection on an index of ovulation rate and the proportion of ova shed that resulted in fully formed offspring; UT = selection on uterine capacity measured as litter size from females unilaterally ovariectomized at 4 wk of age; and LC = unselected control. All females in the present evaluation (a total of 1,932) were unilaterally ovariectomized (either left or right ovary excised) at 4 wk, mated at 9 wk, and killed at d 17 of gestation. The number of corpora lutea and number of fetuses were counted to measure ovulation rate and uterine capacity, respectively. Selection in IX, LS, and UT increased ( P \u3c .01) ovulation rate from unilaterally ovariectomized females but by a greater amount ( P \u3c .01) in IX and LS than in UT. Selection also increased (P \u3c . O l ) uterine capacity of IX, LS, and UT (average response relative to LC = 1.76 pups); response was at least as great in LS and IX as in UT. Direct selection in UT was successful at improving uterine capacity but was no more effective than IX or LS selection. Cases in which ovulation rate limited expression of uterine capacity in UT may have shifted some selection emphasis to ovulation rate and reduced response in uterine capacity
Rapid communication: Linkage mapping of the porcine Agouti gene
Genus and Species. Sus scrofa. Locus. Porcine agouti gene. Source and Description of Primers. The forward primer was designed from pig sequence (GenBank accession no. AF018166) and the reverse primer was developed from comparing the homologous regions of mouse and bovine agouti sequences (GenBank accession no. L06451 and X99691, respectively). The primers were used to amplify approximately 1.4 kb of the porcine agouti gene fragment spanning exons 2 and 3. Sequences of the PCR fragment revealed 83% and 89% exonic identities to the corresponding human and bovine agouti nucleotide sequences, respectively. The porcine agouti sequence has been submitted to GenBank, accession no. AF133261
Measurements of differential cross sections of Z/gamma*+jets+X events in proton anti-proton collisions at sqrt{s}=1.96 TeV
We present cross section measurements for Z/gamma*+jets+X production,
differential in the transverse momenta of the three leading jets. The data
sample was collected with the D0 detector at the Fermilab Tevatron proton
anti-proton collider at a center-of-mass energy of 1.96 TeV and corresponds to
an integrated luminosity of 1 fb-1. Leading and next-to-leading order
perturbative QCD predictions are compared with the measurements, and agreement
is found within the theoretical and experimental uncertainties. We also make
comparisons with the predictions of four event generators. Two
parton-shower-based generators show significant shape and normalization
differences with respect to the data. In contrast, two generators combining
tree-level matrix elements with a parton shower give a reasonable description
of the the shapes observed in data, but the predicted normalizations show
significant differences with respect to the data, reflecting large scale
uncertainties. For specific choices of scales, the normalizations for either
generator can be made to agree with the measurements.Comment: Published in PLB. 11 pages, 3 figure
Search for Large extra spatial dimensions in the dielectron and diphoton channels in collisions at 1.96 TeV
We report on a search for large extra spatial dimensions in the dielectron
and diphoton channels using a data sample of 1.05 \invfb of \ppb collisions at
a center-of-mass energy of 1.96 TeV collected by the D0 detector at the
Fermilab Tevatron Collider. The invariant mass spectrum of the data agrees well
with the prediction of the standard model. We find 95% C.L. lower limits on the
effective Planck scale between 2.1 and 1.3 TeV for 2 to 7 extra dimensions.Comment: 7 pages, 3 figures, 3 tables, submitted to Phys. Rev. Let
Direct measurement of the mass difference between top and antitop quarks
We present a direct measurement of the mass difference between top and
antitop quarks (dm) in lepton+jets top-antitop final states using the "matrix
element" method. The purity of the lepton+jets sample is enhanced for
top-antitop events by identifying at least one of the jet as originating from a
b quark. The analyzed data correspond to 3.6 fb-1 of proton-antiproton
collisions at 1.96 TeV acquired by D0 in Run II of the Fermilab Tevatron
Collider. The combination of the e+jets and mu+jets channels yields dm = 0.8
+/- 1.8 (stat) +/- 0.5 (syst) GeV, which is in agreement with the standard
model expectation of no mass difference.Comment: submitted to Phys. Rev.
Search for charged massive long-lived particles with the D0 detector
We search for charged massive long-lived particles using 1.1 fb of
data collected by the D0 detector at the Fermilab Tevatron Collider.
Time-of-flight information is used to search for pair produced long-lived tau
sleptons, gaugino-like charginos, and higgsino-like charginos. We find no
evidence of a signal and set 95% C.L. cross section upper limits for staus,
which vary from 0.31pb to 0.04pb for stau masses between 60 GeV and 300 GeV. We
also set lower mass limits of 206 GeV (171 GeV) for pair produced charged
gauginos (higgsinos).Comment: To be submitted to Phys. Rev. Letters, V2: updated the figures and
references, V3: final version submitted to PRL and changes in title and
abstracts from "stable" to "long-lived
Search for Zgamma events with large missing transverse energy in ppbar collisions at sqrt(s)=1.96 TeV
We present the first search for supersymmetry (SUSY) in Zgamma final states
with large missing transverse energy using data corresponding to an integrated
luminosity of 6.2 fb-1 collected with the D0 experiment in ppbar collisions at
sqrt(s)=1.96 TeV. This signature is predicted in gauge-mediated SUSY-breaking
models, where the lightest neutralino is the next-to-lightest supersymmetric
particle (NLSP) and is produced in pairs, possibly through decay from heavier
supersymmetric particles. The NLSP can decay either to a Z boson or a photon
and an associated gravitino that escapes detection. We exclude this model at
the 95% C.L. for SUSY breaking scales of Lambda < 87 TeV, corresponding to
neutralino masses of < 151 GeV.Comment: submitted to Phys. Rev. Let
Search for Decay
We have searched for the charmless hadronic decay of B0 mesons into two
neutral pions. Using 9.13fb^-1 taken at the Upsilon(4S) with the CLEO detector,
we obtain an improved upper limit for the branching fraction BR(B0-->pi0pi0) <
5.7*10^-6 at the 90% confidence level.Comment: pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Precise measurement of the top quark mass in the dilepton channel at D0
We measure the top quark mass (mt) in ppbar collisions at a center of mass
energy of 1.96 TeV using dilepton ttbar->W+bW-bbar->l+nubl-nubarbbar events,
where l denotes an electron, a muon, or a tau that decays leptonically. The
data correspond to an integrated luminosity of 5.4 fb-1 collected with the D0
detector at the Fermilab Tevatron Collider. We obtain mt = 174.0 +- 1.8(stat)
+- 2.4(syst) GeV, which is in agreement with the current world average mt =
173.3 +- 1.1 GeV. This is currently the most precise measurement of mt in the
dilepton channel.Comment: 7 pages, 4 figure
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