1,364 research outputs found
A poorly known case of watershed transposition between the São Francisco and upper Paraná river basins
Pairing symmetry of superconducting graphene
The possibility of intrinsic superconductivity in alkali-coated graphene
monolayers has been recently suggested theoretically. Here, we derive the
possible pairing symmetries of a carbon honeycomb lattice and discuss their
phase diagram. We also evaluate the superconducting local density of states
(LDOS) around an isolated impurity. This is directly related to scanning
tunneling microscopy experiments, and may evidence the occurrence of
unconventional superconductivity in graphene.Comment: Eur. Phys. J. B, to appea
Phonon-mediated anisotropic superconductivity in the Y and Lu nickel borocarbides
We present scanning tunneling spectroscopy and microscopy measurements at low
temperatures in the borocarbide materials RNi2B2C (R=Y, Lu). The characteristic
strong coupling structure due to the pairing interaction is unambiguously
resolved in the superconducting density of states. It is located at the
superconducting gap plus the energy corresponding to a phonon mode identified
in previous neutron scattering experiments. These measurements also show that
this mode is coupled to the electrons through a highly anisotropic
electron-phonon interaction originated by a nesting feature of the Fermi
surface. Our experiments, from which we can extract a large electron-phonon
coupling parameter lambda (between 0.5 and 0.8), demonstrate that this
anisotropic electron-phonon coupling has an essential contribution to the
pairing interaction. The tunneling spectra show an anisotropic s-wave
superconducting gap function.Comment: 5 pages, 3 figure
Homocysteine-betaine interactions in a murine model of 5,10-methylenetetrahydrofolate reductase deficiency.
Hyperhomocysteinemia, a proposed risk factor for cardiovascular disease, is also observed in other common disorders. The most frequent genetic cause of hyperhomocysteinemia is a mutated methylenetetrahydrofolate reductase (MTHFR), predominantly when folate status is impaired. MTHFR synthesizes a major methyl donor for homocysteine remethylation to methionine. We administered the alternate choline-derived methyl donor, betaine, to wild-type mice and to littermates with mild or severe hyperhomocysteinemia due to hetero- or homozygosity for a disruption of the Mthfr gene. On control diets, plasma homocysteine and liver choline metabolite levels were strongly dependent on the Mthfr genotype. Betaine supplementation decreased homocysteine in all three genotypes, restored liver betaine and phosphocholine pools, and prevented severe steatosis in Mthfr-deficient mice. Increasing betaine intake did not further decrease homocysteine. In humans with cardiovascular disease, we found a significant negative correlation between plasma betaine and homocysteine concentrations. Our results emphasize the strong interrelationship between homocysteine, folate, and choline metabolism. Hyperhomocysteinemic Mthfr-compromised mice appear to be much more sensitive to changes of choline/betaine intake than do wild-type animals. Hyperhomocysteinemia, in the range of that associated with folate deficiency or with homozygosity for the 677T MTHFR variant, may be associated with disturbed choline metabolism
Yield and mineral nutrition of soybean, maize, and Congo signal grass as affected by limestone and slag
Efeitos da aplicação de retardador (CCC) e acelerador (GA) de crescimento na morfologia e produtividade do feijoeiro (Phaseolus vulgaris L. cv. Carioca)
Verificou-se os efeitos de CCC e GA quando aplicados sob a forma de pulverização das plântulas, na morfologia, florescimento e produtividade do feijoeiro cultivar Carioca, em condições de casa de vegetação. Estudou-se as concentrações de 500, 2000 e 4000 ppm de CCC juntamente com 50 pprn de GA; sendo que CCC 500 + GA 50 ppm promoveu aceleração no crescimento da haste principal e CCC 4000 + GA 50 ppm retardou esse crescimento em relação ao controle. Aplicação de CCC 500 + GA 50 ppm aumentou o número de folhas do feijoeiro. Num período de 2 semanas após o tratamento com CCC 500 + GA 50 ppm ocorreu aumento no comprimento dos meritalos, sendo que 30 dias após a aplicação de CCC 4000 + GA 50 ppm verificou-se diminuição no comprimento dos mesmos. Observou-se aumento no comprimento do limbo foliar 5 dias após os tratamentos com CCC 500 + GA 50 ppm ou CCC 2000 + GA 50 ppm. Ocorreu aumento no número médio de flores com aplicação de CCC 500 + GA 50 ppm. Não ocorreram diferenças significativas entre a produtividade das plantas tratadas com relação ao controle.In this paper the autors tested the effects of (2 - chloroethyl) trimethylammonium chloride (CCC) and gibberellic acid (GA) on the cultivar Carioca of bean, in three different concentrations (500, 2000, and 4000 ppm) of CCC and one concentration of GA (50 ppm). Treatment with CCC 500 ppm + GA 50 ppm increased the height of bean plant and CCC 4000 ppm + GA 50 ppm reduced the height of Phaseolus vulgaris. Application of CCC 500 ppm + GA 50 ppm or CCC 2000 ppm + GA 50 ppm increased the leaf number of bean plant. CCC 500 ppm + GA 50 ppm promoted a increase in the internode length and CCC 4000 ppm + GA 50 ppm reduced the length of internodcs. Application of CCC 500 ppm + GA 50 ppm or CCC 2000 ppm + GA 50 ppm increased the leaf length 5 days after the treatment. CCC 500 ppm + GA 50 ppm promoted higher flowering in relation to the check.
Ação de reguladores vegetais no crescimento de tomateiro (Lycopersicon esculentum Mill. cv. «Miguel Pereira»)
This research deals with the effects of exogenous growth regulators on development of the tomato cultivar «Miguel Pereira». Observations of tomato plants treated with (2-chloroethyl) trimethylammonium chloride (2,000 ppm) and succinic acid -2,2-d:methyi-hydrazide (3,000 ppm) showed that growth regulators induced little variation in plant height. Gibberellic acid (100 ppm) caused greater variation in height.Estudaram-se em condições de casa de vegetação, os efeitos da aplicação de reguladores vegetais no crescimento do tomateiro cultivar "Miguel Pereira". Além do tratamento controle, aplicou-se, 44 dias após a semeadura, cloreto de (2-cloroetil) trimetilamônio 2.000 ppm, ácido succínico -2,2-dimetilhidrazida 3.000 ppm e ácido giberélico 100 ppm. Observou-se que o GA promoveu maior crescimento, em relação ao controle. O crescimento do tomateiro mostrou-se mais reduzido nas plantas tratadas com CCC e SADH, com relação àquelas pulverizadas com GA e plantas controle
Observation of Orbitally Excited B_s Mesons
We report the first observation of two narrow resonances consistent with
states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar
collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the
Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed
as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+,
\bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1})
= 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let
Measurement of the Charged Multiplicities in b, c and Light Quark Events from Z0 Decays
Average charged multiplicities have been measured separately in , and
light quark () events from decays measured in the SLD experiment.
Impact parameters of charged tracks were used to select enriched samples of
and light quark events, and reconstructed charmed mesons were used to select
quark events. We measured the charged multiplicities:
,
, from
which we derived the differences between the total average charged
multiplicities of or quark events and light quark events: and . We compared
these measurements with those at lower center-of-mass energies and with
perturbative QCD predictions. These combined results are in agreement with the
QCD expectations and disfavor the hypothesis of flavor-independent
fragmentation.Comment: 19 pages LaTex, 4 EPS figures, to appear in Physics Letters
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