359 research outputs found
A note on resistance to Hessian fly (Mayetiola destructor) [Diptera : Cecidomyidae] biotype L in tribe Triticeae
Quarante et une accessions de blés primitifs et indigènes (Triticum spp.), 16 accessions du genre Aegilops et 20 accessions ou cultivars du genre Agropyron ont été évaluées pour la première fois pour leur réaction au biotype L de la mouche de Hesse (Mayetiola destructor). Trois accessions du Triticum monococcum, 13 accessions du genre Aegilops et 13 accessions ou cultivars du genre Agropyron ont été trouvées résistantes de façon homogène. L'antibiose s'est manifestée dans certains cas mais dans certains autres, il est apparu une résistance physique attribuable à la présence de la pubescence foliaire ou de la ligule. La pubescence du Triticum boeoticum n'a pas été efficace afin de procurer de la résistance.Forty-one accessions of primitive and wild wheats (Triticum species), 16 accessions of Aegilops species, and 20 accessions or cultivars of Agropyron species were evaluated for the first time for reaction to biotype L of Hessian fly (Mayetiola destructor). Three accessions of Triticum monococcum, 13 accessions of Aegilops species, and 13 accessions or cultivars of Agropyron species were found homogeneously resistant. Antibiosis was operative in some cases but in others there appeared to be physical resistance due to the presence of leaf pubescence or ligule. Pubescence of Triticum boeoticum was not effective in providing resistance
Angiotensin-Converting Enzyme Inhibitor Therapy Affects Left Ventricular Mass in Patients With Ejection Fraction >40% After Acute Myocardial Infarction
AbstractObjectives. We tested the hypothesis that angiotensin-converting enzyme (ACE) inhibitor therapy decreases left ventricular (LV) mass in patients with a left ventricular ejection fraction (LVEF) >40% and no evidence of heart failure after their first acute Q wave myocardial infarction (MI).Background. Recently, ACE inhibitor therapy has been shown to have an early mortality benefit in unselected patients with acute MI, including patients without heart failure and a LVEF >35%. However, the effects on LV mass and volume in this patient population have not been studied.Methods. Thirty-five patients with a LVEF >40% after their first acute Q wave MI were randomized to titrated oral ramipril (n = 20) or conventional therapy (control, n = 15). Magnetic resonance imaging (MRI) performed an average of 7 days and 3 months after MI provided LV volumes and mass from summated serial short-axis slices.Results. Left ventricular end-diastolic volume index did not change in ramipril-treated patients (62 ± 16 [SD] to 66 ± 17 ml/m2) or in control patients (62 ± 16 to 68 ± 17 ml/m2), and stroke volume index increased significantly in both groups. However, LV mass index decreased in ramipril-treated patients (82 ± 18 to 73 ± 19 g/m2, p = 0.0002) but not in the control patients (77 ± 15 to 79 ± 23 g/m2). Systolic arterial pressure did not change in either group at 3-month follow-up.Conclusions. In patients with a LVEF >40% after acute MI, ramipril decreased LV mass, and blood pressure and LV function were unchanged after 3 months of therapy. Whether the decrease in mass represents a sustained effect that is associated with a decrease in morbid events requires further investigation.(J Am Coll Cardiol 1997;29:49–54)
Indirect Dark Matter Detection from Dwarf Satellites: Joint Expectations from Astrophysics and Supersymmetry
We present a general methodology for determining the gamma-ray flux from
annihilation of dark matter particles in Milky Way satellite galaxies, focusing
on two promising satellites as examples: Segue 1 and Draco. We use the
SuperBayeS code to explore the best-fitting regions of the Constrained Minimal
Supersymmetric Standard Model (CMSSM) parameter space, and an independent MCMC
analysis of the dark matter halo properties of the satellites using published
radial velocities. We present a formalism for determining the boost from halo
substructure in these galaxies and show that its value depends strongly on the
extrapolation of the concentration-mass (c(M)) relation for CDM subhalos down
to the minimum possible mass. We show that the preferred region for this
minimum halo mass within the CMSSM with neutralino dark matter is ~10^-9-10^-6
solar masses. For the boost model where the observed power-law c(M) relation is
extrapolated down to the minimum halo mass we find average boosts of about 20,
while the Bullock et al (2001) c(M) model results in boosts of order unity. We
estimate that for the power-law c(M) boost model and photon energies greater
than a GeV, the Fermi space-telescope has about 20% chance of detecting a dark
matter annihilation signal from Draco with signal-to-noise greater than 3 after
about 5 years of observation
A Study of the Roper Resonance as a Hybrid State from Decays
The structure of the Roper resonance as a hybrid baryon is investigated
through studying the transitional amplitudes in J/psi-> p\barN*, N*\barN*
decays. We begin with perturbative QCD to describe the dynamical process for
the J/psi-> 3\bar q+3q decay to the lowest order of \alpha_s, and by extending
the modified quark creation model to the J/psi energy region to describe the
J/psi-> 3\bar q+3q +g process. The non-perturbative effects are incorporated by
a simple quark model of baryons to evaluate the angular distribution parameters
and decay widths for the processes J/psi-> pbar N*,N*bar N*. From fitting the
decay width of J/psi->gamma p pbar to the experimental data, we extract the
quark-pair creation strength g_I=15.40 GeV. Our numerical results for
J/psi->pbar N*,N* bar N* decays show that the branching ratios for these decays
are quite different if the Roper resonance is assumed to be a common state
or a pure hybrid state. For testing its mixing properties, we present a scheme
to construct the Roper wave function by mixing |qqqg> state with a normal
|qqq,2s> state. Under this picture, the ratios of the decay widths to that of
the J/psi->p pbar decay are re-evaluated versus the mixing parameter. A test of
the hybrid nature of the Roper resonance in J/psi decays is discussed.Comment: 18 pages,3 figures, To appear in Nuclear Physics
Characterisation and calibration of low-cost PM sensors at high temporal resolution to reference-grade performance
Particulate Matter (PM) low-cost sensors (LCS) present a cost-effective opportunity to improve the spatiotemporal resolution of airborne PM data. Previous studies focused on PM-LCS-reported hourly data and identified, without fully addressing, their limitations. However, PM-LCS provide measurements at finer temporal resolutions. Furthermore, government bodies have developed certifications to accompany new uses of these sensors, but these certifications have shortcomings. To address these knowledge gaps, PM-LCS of two models, 8 Sensirion SPS30 and 8 Plantower PMS5003, were collocated for one year with a Fidas 200S, MCERTS-certified PM monitor and were characterised at 2 min resolution, enabling replication of certification processes, and highlighting their limitations and improvements. Robust linear models using sensor-reported particle number concentrations and relative humidity, coupled with 2-week biannual calibration campaigns, achieved reference-grade performance, at median PM2.5 background concentration of 5.5 μg/m3, demonstrating that, with careful calibration, PM-LCS may cost-effectively supplement reference equipment in multi-nodes networks with fine spatiotemporality
Anthropogenic Space Weather
Anthropogenic effects on the space environment started in the late 19th
century and reached their peak in the 1960s when high-altitude nuclear
explosions were carried out by the USA and the Soviet Union. These explosions
created artificial radiation belts near Earth that resulted in major damages to
several satellites. Another, unexpected impact of the high-altitude nuclear
tests was the electromagnetic pulse (EMP) that can have devastating effects
over a large geographic area (as large as the continental United States). Other
anthropogenic impacts on the space environment include chemical release ex-
periments, high-frequency wave heating of the ionosphere and the interaction of
VLF waves with the radiation belts. This paper reviews the fundamental physical
process behind these phenomena and discusses the observations of their impacts.Comment: 71 pages, 35 figure
Measurement of Leading Proton and Neutron Production in Deep Inelastic Scattering at HERA
Deep--inelastic scattering events with a leading baryon have been detected by
the H1 experiment at HERA using a forward proton spectrometer and a forward
neutron calorimeter. Semi--inclusive cross sections have been measured in the
kinematic region 2 <= Q^2 <= 50 GeV^2, 6.10^-5 <= x <= 6.10^-3 and baryon p_T
<= MeV, for events with a final state proton with energy 580 <= E' <= 740 GeV,
or a neutron with energy E' >= 160 GeV. The measurements are used to test
production models and factorization hypotheses. A Regge model of leading baryon
production which consists of pion, pomeron and secondary reggeon exchanges
gives an acceptable description of both semi-inclusive cross sections in the
region 0.7 <= E'/E_p <= 0.9, where E_p is the proton beam energy. The leading
neutron data are used to estimate for the first time the structure function of
the pion at small Bjorken--x.Comment: 30 pages, 9 figures, 2 tables, submitted to Eur. Phys.
The Earth: Plasma Sources, Losses, and Transport Processes
This paper reviews the state of knowledge concerning the source of magnetospheric plasma at Earth. Source of plasma, its acceleration and transport throughout the system, its consequences on system dynamics, and its loss are all discussed. Both observational and modeling advances since the last time this subject was covered in detail (Hultqvist et al., Magnetospheric Plasma Sources and Losses, 1999) are addressed
Charmonium Production in Deep Inelastic Scattering at HERA
The electroproduction of J/psi and psi(2S) mesons is studied in elastic, quasi-elastic and inclusive reactions for four momentum transfers 2 Q^2 80 GeV^2 and photon-proton centre of mass energies 25 W 180 GeV. The data were taken with the H1 detector at the electron proton collider HERA in the years 1995 to 1997. The total virtual photon-proton cross section for elastic J/psi production is measured as a function of Q^2 and W. The dependence of the production rates on the square of the momentum transfer from the proton (t) is extracted. Decay angular distributions are analysed and the ratio of the longitudinal and transverse cross sections is derived. The ratio of the cross sections for quasi-elastic psi(2S) and J/psi meson production is measured as a function of Q^2. The results are discussed in terms of theoretical models based upon perturbative QCD. Differential cross sections for inclusive and inelastic production of J/psi mesons are determined and predictions within two theoretical frameworks are compared with the data, the non-relativistic QCD factorization approach including colour octet and colour singlet contributions, and the model of Soft Colour Interactions
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