586 research outputs found
Earliest hominin cancer: 1.7-million-year- old osteosarcoma from Swartkrans Cave, South Africa
The reported incidence of neoplasia in the extinct human lineage is rare, with only a few confirmed
cases of Middle or Later Pleistocene dates reported. It has generally been assumed that premodern
incidence of neoplastic disease of any kind is rare and limited to benign conditions,
but new fossil evidence suggests otherwise. We here present the earliest identifiable case of
malignant neoplastic disease from an early human ancestor dated to 1.8–1.6 million years old.
The diagnosis has been made possible only by advances in 3D imaging methods as diagnostic
aids. We present a case report based on re-analysis of a hominin metatarsal specimen (SK 7923)
from the cave site of Swartkrans in the Cradle of Humankind, South Africa. The expression
of malignant osteosarcoma in the Swartkrans specimen indicates that whilst the upsurge in
malignancy incidence is correlated with modern lifestyles, there is no reason to suspect that
primary bone tumours would have been any less frequent in ancient specimens. Such tumours
are not related to lifestyle and often occur in younger individuals. As such, malignancy has a
considerable antiquity in the fossil record, as evidenced by this specimen.NCS201
Amixicile reduces severity of cryptosporidiosis but does not have in vitro activity against Cryptosporidium
Cryptosporidium species cause significant morbidity in malnourished children. Nitazoxanide (NTZ) is the only approved treatment for cryptosporidiosis, but NTZ has diminished effectiveness during malnutrition. Here, we show that amixicile, a highly selective water-soluble derivative of NTZ diminishes Cryptosporidium infection severity in a malnourished mouse model despite a lack of direct anticryptosporidial activity. We suggest that amixicile, by tamping down anaerobes associated with intestinal inflammation, reverses weight loss and indirectly mitigates infection-associated pathology
Large-Scale Power Spectrum and Structures From the ENEAR galaxy Peculiar Velocity Catalog
We estimate the mass density fluctuations power spectrum (PS) on large scales
by applying a maximum likelihood technique to the peculiarvelocity data of the
recently completed redshift-distance survey of early-type galaxies (ENEAR). The
general results are in agreement with the high amplitude power spectra found
from similar analysis of other independent all-sky catalogs of peculiar
velocity data such as MARK III and SFI. For Lambda & Open CDM COBE normalized
PS models, the best-fit parameters are confined by a contour approximately
defined by Omega h^{1.3}=0.377+-0.08 and Omega h^{0.88}=0.517+-0.083,
respectively. Gamma-shape models, free of COBE normalization, resultsin the
weak constraint of and in the rather stringent constraint of
sigma_8 Omega^{0.6}=1.0+-0.25. All quoted uncertainties refer to 3-sigma
confidence-level. The calculated PS is used as a prior for Wiener
reconstruction of the density field at different resolutions and the
three-dimensional velocity field within a volume of radius ~80 Mpc/h. All major
structures in the nearby universe are recovered and are well matched to those
predicted from all-sky redshift surveys.Comment: Submitted to MNRAS, 11 Pages, 9 figure
Associations between neutering and idiopathic epilepsy in Labrador retrievers and Border collies under primary veterinary care in the UK
There are sparse published scientific data on associations between neutering and the severity and survival of dogs with idiopathic epilepsy. This study aimed to explore the timing of neutering with respect to onset of seizures in dogs with idiopathic epilepsy. Associations between neutering and both age of onset of seizures and the occurrence of cluster seizures or status epilepticus were examined. Survival analysis investigated the effects of sex-neuter categories. The median survival time of Border collies was compared with data previously reported in literature.
The study included veterinary primary-care clinical data on 117 Labrador retrievers and 57 Border collies diagnosed with idiopathic epilepsy from the VetCompass project in the UK. The majority (74.2%; P ≤ 0.001) of neutered cases were neutered before the onset of seizures. Age (years) at onset of seizures did not differ between dogs intact at time of onset and dogs neutered before onset of seizures (males 3.6 vs. 3.7; P = 0.468 and females 3.4 vs. 4.1; P = 0.154). Neuter status was not associated with the occurrence of cluster seizures (males P = 0.947 and females P = 0.844). Dogs intact at onset of seizures had longer median survival times than dogs neutered before onset of seizures (males, 1436 days vs. 1234 days; P = 0.019; females, 1778.5 days vs. 1261 days; P = 0.027). Median survival time of 1393 days for Border collies was longer than previously reported (P ≤ 0.001). These results do not support recommendations to neuter dogs with idiopathic epilepsy within an evidence-based treatment plan
Ultra-High Energy Neutrino Fluxes and Their Constraints
Applying our recently developed propagation code we review extragalactic
neutrino fluxes above 10^{14} eV in various scenarios and how they are
constrained by current data. We specifically identify scenarios in which the
cosmogenic neutrino flux, produced by pion production of ultra high energy
cosmic rays outside their sources, is considerably higher than the
"Waxman-Bahcall bound". This is easy to achieve for sources with hard injection
spectra and luminosities that were higher in the past. Such fluxes would
significantly increase the chances to detect ultra-high energy neutrinos with
experiments currently under construction or in the proposal stage.Comment: 11 pages, 15 figures, version published in Phys.Rev.
Measurement of the partial widths of the Z into up- and down-type quarks
Using the entire OPAL LEP1 on-peak Z hadronic decay sample, Z -> qbarq gamma
decays were selected by tagging hadronic final states with isolated photon
candidates in the electromagnetic calorimeter. Combining the measured rates of
Z -> qbarq gamma decays with the total rate of hadronic Z decays permits the
simultaneous determination of the widths of the Z into up- and down-type
quarks. The values obtained, with total errors, were Gamma u = 300 ^{+19}_{-18}
MeV and Gamma d = 381 ^{+12}_{-12} MeV. The results are in good agreement with
the Standard Model expectation.Comment: 22 pages, 5 figures, Submitted to Phys. Letts.
Search for R-Parity Violating Decays of Scalar Fermions at LEP
A search for pair-produced scalar fermions under the assumption that R-parity
is not conserved has been performed using data collected with the OPAL detector
at LEP. The data samples analysed correspond to an integrated luminosity of
about 610 pb-1 collected at centre-of-mass energies of sqrt(s) 189-209 GeV. An
important consequence of R-parity violation is that the lightest supersymmetric
particle is expected to be unstable. Searches of R-parity violating decays of
charged sleptons, sneutrinos and squarks have been performed under the
assumptions that the lightest supersymmetric particle decays promptly and that
only one of the R-parity violating couplings is dominant for each of the decay
modes considered. Such processes would yield final states consisting of
leptons, jets, or both with or without missing energy. No significant
single-like excess of events has been observed with respect to the Standard
Model expectations. Limits on the production cross- section of scalar fermions
in R-parity violating scenarios are obtained. Constraints on the supersymmetric
particle masses are also presented in an R-parity violating framework analogous
to the Constrained Minimal Supersymmetric Standard Model.Comment: 51 pages, 24 figures, Submitted to Eur. Phys. J.
Measurement of the Hadronic Photon Structure Function F_2^gamma at LEP2
The hadronic structure function of the photon F_2^gamma is measured as a
function of Bjorken x and of the factorisation scale Q^2 using data taken by
the OPAL detector at LEP. Previous OPAL measurements of the x dependence of
F_2^gamma are extended to an average Q^2 of 767 GeV^2. The Q^2 evolution of
F_2^gamma is studied for average Q^2 between 11.9 and 1051 GeV^2. As predicted
by QCD, the data show positive scaling violations in F_2^gamma. Several
parameterisations of F_2^gamma are in agreement with the measurements whereas
the quark-parton model prediction fails to describe the data.Comment: 4 pages, 2 figures, to appear in the proceedings of Photon 2001,
Ascona, Switzerlan
A measurement of the tau mass and the first CPT test with tau leptons
We measure the mass of the tau lepton to be 1775.1+-1.6(stat)+-1.0(syst.) MeV
using tau pairs from Z0 decays. To test CPT invariance we compare the masses of
the positively and negatively charged tau leptons. The relative mass difference
is found to be smaller than 3.0 10^-3 at the 90% confidence level.Comment: 10 pages, 4 figures, Submitted to Phys. Letts.
Measurement of Rb in e+e- Collisions at 182 - 209 GeV
Measurements of Rb, the ratio of the bbbar cross-section to the qqbar cross-
section in e+e- collisions, are presented. The data were collected by the OPAL
experiment at LEP at centre-of-mass energies between 182 GeV and 209 GeV.
Lepton, lifetime and event shape information is used to tag events containing b
quarks with high efficiency. The data are compatible with the Standard Model
expectation. The mean ratio of the eight measurements reported here to the
Standard Model prediction is 1.055+-0.031+-0.037, where the first error is
statistical and the second systematic.Comment: 21 pages, 5 figures, Submitted to Phys. Letts
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