2,428 research outputs found
The Bering Sea ice cover during March 1979: Comparison of surface and satellite data with the Nimbus-7 SMMR
During March 1979, field operations were carried out in the Marginal Ice Zone (MIZ) of the Bering Sea. The field measurements which included oceanographic, meteorological and sea ice observations were made nearly coincident with a number of Nimbus-7 and Tiros-N satellite observations. The results of a comparison between surface and aircraft observations, and images from the Tiros-N satellite, with ice concentrations derived from the microwave radiances of the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) are given. Following a brief discussion of the field operations, including a summary of the meteorological conditions during the experiment, the satellite data is described with emphasis on the Nimbus-7 SMMR and the physical basis of the algorithm used to retrieve ice concentrations
Comparison of the initial ovarian response, the synchrony of oestrus and ovulation and chronic stress response after administration of 100 or 250 μg of GnRH to randomly cycling Bos indicus cattle
Objective: This study investigated the effects of administering saline, 100 or 250 μg of gonadotrophin releasing hormone (GnRH) on ovarian response, synchrony of oestrus and ovulation and chronic stress response in Bos indicus cattle.
Design: Randomised control.
Methods: Animals were either left untreated (n = 20) or on day 0 treated with an intravaginal progesterone releasing device and either saline (n = 24), 100 μg (n = 35), or 250 (n = 35) μg of GnRH, intramuscular (IM). Blood was sampled 1.4 h after administration of treatment to monitor concentrations of luteinising hormone (LH) and P4 in serum and again 5 days later. On day 5 intravaginal P4 releasing device were removed, cloprostenol was administered IM and again 8 h later. Oestrus and ovulation were then monitored with ultrasonography for 6.5 days. Hair was clipped on day 55 for analysis of hair cortisol concentrations (HCC).
Results: No significant differences were found between Saline and GnRH treatments in the odds of inducing a new corpus luteum (CL) and the synchrony of oestrus or ovulation. HCC did not differ significantly between treatments. Mean concentrations of LH in serum on day 0 were less in the Saline compared to 100 and 250 μg GnRH treatments but did not differ between different doses of GnRH.
Conclusion: Mean concentrations of LH and the odds of inducing a new CL were not increased after administering 250 μg compared to 100 μg of GnRH. Animal handling events in the study did not influence HCC. Further research is needed to better optimise responses to GnRH in B. indicus cattle
Avaliação da seletividade inicial de herbicidas para o tomateiro por meio da análise de fluorescência da clorofila.
Objetivou-se com este trabalho analisar a fluorescência da clorofila por meio da avaliação da taxa de transporte de eletrons em tomateiro como forma de avaliar a seletividade inicial de hervicidas aplicados em pré-transplate
Statistical regimes of random laser fluctuations
Statistical fluctuations of the light emitted from amplifying random media
are studied theoretically and numerically. The characteristic scales of the
diffusive motion of light lead to Gaussian or power-law (Levy) distributed
fluctuations depending on external control parameters. In the Levy regime, the
output pulse is highly irregular leading to huge deviations from a mean--field
description. Monte Carlo simulations of a simplified model which includes the
population of the medium, demonstrate the two statistical regimes and provide a
comparison with dynamical rate equations. Different statistics of the
fluctuations helps to explain recent experimental observations reported in the
literature.Comment: Revised version, resubmitted to Physical Review
Phosphodiesterase isoforms and cAMP compartments in the development of new therapies for obstructive pulmonary diseases
The second messenger molecule 3′5′-cyclic adenosine monophosphate (cAMP) imparts several beneficial effects in lung diseases such as asthma, chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). While cAMP is bronchodilatory in asthma and COPD, it also displays anti-fibrotic properties that limit fibrosis. Phosphodiesterases (PDEs) metabolize cAMP and thus regulate cAMP signaling. While some existing therapies inhibit PDEs, there are only broad family specific inhibitors. The understanding of cAMP signaling compartments, some centered around lipid rafts/caveolae, has led to interest in defining how specific PDE isoforms maintain these signaling microdomains. The possible altered expression of PDEs, and thus abnormal cAMP signaling, in obstructive lung diseases has been poorly explored. We propose that inhibition of specific PDE isoforms can improve therapy of obstructive lung diseases by amplifying specific cAMP signals in discreet microdomains
Driving magnetic order in a manganite by ultrafast lattice excitation
Optical control of magnetism, of interest for high-speed data processing and
storage, has only been demonstrated with near-infrared excitation to date.
However, in absorbing materials, such high photon energies can lead to
significant dissipation, making switch back times long and miniaturization
challenging. In manganites, magnetism is directly coupled to the lattice, as
evidenced by the response to external and chemical pressure, or to
ferroelectric polarization. Here, femtosecond mid-infrared pulses are used to
excite the lattice in La0.5Sr1.5MnO4 and the dynamics of electronic order are
measured by femtosecond resonant soft x-ray scattering with an x-ray free
electron laser. We observe that magnetic and orbital orders are reduced by
excitation of the lattice. This process, which occurs within few picoseconds,
is interpreted as relaxation of the complex charge-orbital-spin structure
following a displacive exchange quench - a prompt shift in the equilibrium
value of the magnetic and orbital order parameters after the lattice has been
distorted. A microscopic picture of the underlying unidirectional lattice
displacement is proposed, based on nonlinear rectification of the
directly-excited vibrational field, as analyzed in the specific lattice
symmetry of La0.5Sr1.5MnO4. Control of magnetism through ultrafast lattice
excitation has important analogies to the multiferroic effect and may serve as
a new paradigm for high-speed optomagnetism.Comment: 10 pages manuscript, 4 figure
O efeito do arranjo espacial sobre conformação de frutos e teor de sólidos solúveis do hÃbrido BRS Sena.
Este trabalho tem por objetivo determinar a influência do arranjo espacial na conformação dos frutos e no teor de sólidos soluveis.Trabalho 7
Ajuste do espaçamento e da densidade populacional no cultivo rasteiro de tomate destinado ao processamento industrial.
O presente trabalho tevo como objetivo avaliar diferentes combinações de espaçamentos e densidade de platas no desenvolvimento da cultura de tomateiro(BRS Sena) rasteiro destinado à industria.Trabalho 18
Seletividade de herbicidas para o hÃbrido de tomate BRS Sena.
O objetivo deste experimento foi avaliar o nÃvel de fitointoxicação de plantas de tomate (BRS Sena) pela aplicação de herbicidas.Trabalho 19
Advances in Sea-Ice Research Based on Remotely Sensed Passive Microwave Data
The contributions made to our knowledge of polar sea ice since the early 1970s by passive microwave remote sensing are surveyed
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