380 research outputs found
Redox conditions and authigenic mineralization related to cold seeps in central Guaymas Basin, Gulf of California
Authigenic carbonate crusts, surface muds and bivalve shell fragments have been recovered from inactive and active recently discovered cold seep sites in central Guaymas Basin. In this study, for first time, redox conditions and fluid sources involved in mineral precipitation were investigated by analyzing the mineralogy and textures of surface samples, along with skeletal contents, and C, O and S isotopes variations. The d13C values of aragonitic bivalve shells and non-skeletal carbonate from some surface muds (1Ⱐto -3.7ⰠV-PDB) suggest that carbonate precipitated from ambient dissolved inorganic carbon, whereas fibrous aragonite cement and non-skeletal carbonate from other sites are highly depleted in 13C (down to -47.6ⰠV-PDB), suggesting formation via anaerobic oxidation of methane, characteristic of methane seepage environments. d18O in most of the carbonates varies from +1.4Ⱐto +3.2ⰠV-PDB, indicating that they formed from slightly modified seawater. Some non-skeletal carbonate grains from surface muds have lower d18O values (-12.5Ⱐto -8.2ⰠV-PDB) reflecting the influence of 18O-depleted pore water. Size distribution of pyrite framboids (mean value: 3.1¿”m) scattered within diatomaceous sinter suggests formation from anoxic-sulfidic bottom waters. d34S in pyrite is of -0.3ⰠV-CDT compared to +46.6ⰠV-CDT in barite, thus implying a fluid sulfate-sulfide fractionation of 21.3Ⱐthat argues in favor of microbial sulfate reduction as the processes that mediated pyrite framboid formation, in a semi-closed system. Barite formation occurred through the mixing of reducing and Ba-rich seep fluids with a 34S-enriched sulfate pool that resulted from microbial sulfate reduction in a semi-closed system. The chemical composition of aragonite cement, barite and pyrite suggest mineral precipitation from modified seawater. Taken together, our data suggest that mineralization at the studied seep sites is controlled by the mixing of seawater with minor amounts of hydrothermal fluids, and oxygen-depleted conditions favoring anaerobic microbial processes.Peer ReviewedPostprint (author's final draft
Clinical features, diagnosis, and survival analysis of dogs with glioma
Background:
Gliomas in dogs remain poorly understood.
Objectives:
To characterize the clinicopathologic findings, diagnostic imaging features and survival of a large sample of dogs with glioma using the Comparative Brain Tumor Consortium diagnostic classification.
Animals:
Ninety-one dogs with histopathological diagnosis of glioma.
Methods:
Multicentric retrospective case series. Signalment, clinicopathologic findings, diagnostic imaging characteristics, treatment, and outcome were used. Tumors were reclassified according to the new canine glioma diagnostic scheme.
Results:
No associations were found between clinicopathologic findings or survival and tumor type or grade. However, definitive treatments provided significantly (P = .03) improved median survival time (84âdays; 95% confidence interval [CI], 45-190) compared to palliative treatment (26âdays; 95% CI, 11-54). On magnetic resonance imaging (MRI), oligodendrogliomas were associated with smooth margins and T1-weighted hypointensity compared to astrocytomas (odds ratio [OR], 42.5; 95% CI, 2.42-744.97; P = .04; OR, 45.5; 95% CI, 5.78-333.33; Pâ<â.001, respectively) and undefined gliomas (OR, 84; 95% CI, 3.43-999.99; P = .02; OR, 32.3; 95% CI, 2.51-500.00; P = .008, respectively) and were more commonly in contact with the ventricles than astrocytomas (OR, 7.47; 95% CI, 1.03-53.95; P = .049). Tumor spread to neighboring brain structures was associated with high-grade glioma (OR, 6.02; 95% CI, 1.06-34.48; P = .04).
Conclusions and Clinical Importance:
Dogs with gliomas have poor outcomes, but risk factors identified in survival analysis inform prognosis and the newly identified MRI characteristics could refine diagnosis of tumor type and grade
Comparative Study of the Effects of a 1-Year Dietary Intervention of a Low-Carbohydrate Diet Versus a Low-Fat Diet on Weight and Glycemic Control in Type 2 Diabetes
Arabidopsis COGWHEEL1 links light perception and gibberellins with seed tolerance to deterioration
[ES] Significance Statement Seed tolerance to deterioration depends on anti-aging defenses only partially understood. COG1 encodes a transcription factor previously described to attenuate phytochrome responses to light and we found that it is a positive regulator of seed tolerance to deterioration while light perception by phytochromes is negative. The proposed mechanism is that COG1 increases gibberellins levels, leading to a seed coat containing more suberin and less permeable to oxygen. Light is known to inhibit gibberellins action.This work was supported by grant BIO2014-52621-R from the Spanish 'Ministerio de Economia y Competitividad', Madrid. We thank the 'Servicio de Cuantificacion de Hormonas Vegetales' of our institute for the determination of GA, ABA and auxin.Bueso RĂłdenas, E.; Muñoz Bertomeu, J.; Campos, F.; MartĂnez-Ortuño, CJ.; Tello Lacal, C.; MartĂnez-Almonacid, I.; Ballester Fuentes, P.... (2016). 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Search for New Physics in e mu X Data at D0 Using Sleuth: A Quasi-Model-Independent Search Strategy for New Physics
We present a quasi-model-independent search for the physics responsible for
electroweak symmetry breaking. We define final states to be studied, and
construct a rule that identifies a set of relevant variables for any particular
final state. A new algorithm ("Sleuth") searches for regions of excess in those
variables and quantifies the significance of any detected excess. After
demonstrating the sensitivity of the method, we apply it to the semi-inclusive
channel e mu X collected in 108 pb^-1 of ppbar collisions at sqrt(s) = 1.8 TeV
at the D0 experiment during 1992-1996 at the Fermilab Tevatron. We find no
evidence of new high p_T physics in this sample.Comment: 23 pages, 12 figures. Submitted to Physical Review
Search For Heavy Pointlike Dirac Monopoles
We have searched for central production of a pair of photons with high
transverse energies in collisions at TeV using of data collected with the D\O detector at the Fermilab Tevatron in
1994--1996. If they exist, virtual heavy pointlike Dirac monopoles could
rescatter pairs of nearly real photons into this final state via a box diagram.
We observe no excess of events above background, and set lower 95% C.L. limits
of on the mass of a spin 0, 1/2, or 1 Dirac
monopole.Comment: 12 pages, 4 figure
The Dijet Mass Spectrum and a Search for Quark Compositeness in bar{p}p Collisions at sqrt{s} = 1.8 TeV
Using the DZero detector at the 1.8 TeV pbarp Fermilab Tevatron collider, we
have measured the inclusive dijet mass spectrum in the central pseudorapidity
region |eta_jet| < 1.0 for dijet masses greater than 200 Gev/c^2. We have also
measured the ratio of spectra sigma(|eta_jet| < 0.5)/sigma(0.5 < |eta_jet| <
1.0). The order alpha_s^3 QCD predictions are in good agreement with the data
and we rule out models of quark compositeness with a contact interaction scale
< 2.4 TeV at the 95% confidence level.Comment: 11 pages, 4 figures, 2 tables, submitted to Phys. Rev. Let
Search for High Mass Photon Pairs in p-pbar --> gamma-gamma-jet-jet Events at sqrt(s)=1.8 TeV
A search has been carried out for events in the channel p-barp --> gamma
gamma jet jet. Such a signature can characterize the production of a
non-standard Higgs boson together with a W or Z boson. We refer to this
non-standard Higgs, having standard model couplings to vector bosons but no
coupling to fermions, as a "bosonic Higgs." With the requirement of two high
transverse energy photons and two jets, the diphoton mass (m(gamma gamma))
distribution is consistent with expected background. A 90(95)% C.L. upper limit
on the cross section as a function of mass is calculated, ranging from
0.60(0.80) pb for m(gamma gamma) = 65 GeV/c^2 to 0.26(0.34) pb for m(gamma
gamma) = 150 GeV/c^2, corresponding to a 95% C.L. lower limit on the mass of a
bosonic Higgs of 78.5 GeV/c^2.Comment: 9 pages, 3 figures. Replacement has new H->gamma gamma branching
ratios and corresponding new mass limit
Ratio of the Isolated Photon Cross Sections at \sqrt{s} = 630 and 1800 GeV
The inclusive cross section for production of isolated photons has been
measured in \pbarp collisions at GeV with the \D0 detector at
the Fermilab Tevatron Collider. The photons span a transverse energy ()
range from 7-49 GeV and have pseudorapidity . This measurement is
combined with to previous \D0 result at GeV to form a ratio
of the cross sections. Comparison of next-to-leading order QCD with the
measured cross section at 630 GeV and ratio of cross sections show satisfactory
agreement in most of the range.Comment: 7 pages. Published in Phys. Rev. Lett. 87, 251805, (2001
Probing Hard Color-Singlet Exchange in ppbar Collisions at root-s=630 GeV and 1800 GeV
We present results on dijet production via hard color-singlet exchange in
proton-antiproton collisions at root-s = 630 GeV and 1800 GeV using the DZero
detector. The fraction of dijet events produced via color-singlet exchange is
measured as a function of jet transverse energy, separation in pseudorapidity
between the two highest transverse energy jets, and proton-antiproton
center-of-mass energy. The results are consistent with a color-singlet fraction
that increases with an increasing fraction of quark-initiated processes and
inconsistent with two-gluon models for the hard color-singlet.Comment: 16 pages, 6 figure
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