5,521 research outputs found
Concentracion e infeccion de esporangios de Phytophthora infestans (Mont.) de Bary en pre-emergencia de tuberculos de papa (Solanum tuberosum).
Impact of single nucleotide polymorphisms in leptin, leptin receptor, growth hormone receptor, and diacylglycerol acyltransferase (DGAT1) gene loci on milk production, feed, and body energy traits of UK dairy cows
Structural parameters for globular clusters in M31 and generalizations for the fundamental plane
The structures of globular clusters (GCs) reflect their dynamical states and
past histories. High-resolution imaging allows the exploration of morphologies
of clusters in other galaxies. Surface brightness profiles from new Hubble
Space Telescope observations of 34 globular clusters in M31 are presented,
together with fits of several different structural models to each cluster. M31
clusters appear to be adequately fit by standard King models, and do not
obviously require alternate descriptions with relatively stronger halos, such
as are needed to fit many GCs in other nearby galaxies. The derived structural
parameters are combined with corrected versions of those measured in an earlier
survey to construct a comprehensive catalog of structural and dynamical
parameters for M31 GCs with a sample size similar to that for the Milky Way.
Clusters in M31, the Milky Way, Magellanic Clouds, Fornax dwarf spheroidal and
NGC 5128 define a very tight fundamental plane with identical slopes. The
combined evidence for these widely different galaxies strongly reinforces the
view that old globular clusters have near-universal structural properties
regardless of host environment.Comment: AJ in press; 59 pages including 16 figure
HST Imaging of the Globular Clusters in the Fornax Cluster: NGC 1399 and NGC 1404
The Fornax cluster galaxies NGC 1399 and NGC 1404 are ideal for studying the
effects of a cluster environment on globular cluster systems. Here we present
new optical imaging of these two galaxies from both the Hubble Space
Telescope's Wide Field and Planetary Camera 2 and the Cerro Tololo
Inter-American Observatory's 1.5m telescope. The combination of both data sets
provides unique insight on the spatial and colour distribution of globular
clusters. From B-I colours, we find that both galaxies have a broad globular
cluster metallicity distribution that is inconsistent with a single population.
Two Gaussians provide a reasonable representation of the metallicity
distribution in each galaxy. The metal-rich subpopulation is more centrally
concentrated than the metal-poor one. We show that the radial metallicity
gradient can be explained by the changing relative mix of the two globular
cluster subpopulations. We derive globular cluster surface density profiles,
and find that they are flatter (i.e. more extended) than the underlying
starlight. The total number of globular clusters and specific frequency are
calculated to be N = 5700 +/- 500, S_N = 11.5 +/- 1.0 for NGC 1399 and N = 725
+/- 145, S_N = 2.0 +/- 0.5 for NGC 1404. Our results are compared to the
expectations of globular cluster formation scenarios.Comment: 21 pages, Latex, 13 figures, submitted to MNRA
Far-Infrared Emission From E and E/S0 Galaxies
Studies of cold material through IRAS 60um and 100um observations indicated
that half of ordinary E and E/S0 galaxies were detected above the 3 sigma
level, indicating that cold gas is common, although no correlation was found
between the optical and far- infrared fluxes. Most detections were near the
instrumental threshold, and given an improved understanding of detection
confidence, we reconsider the 60um and 100um detection rate. After excluding
active galactic nuclei, peculiar systems, and background contamination, only 15
non-peculiar E and E/S0 galaxies from the RSA catalog are detected above the
98% confidence level, about 12% of the sample. An unusually high percentage of
these 15 galaxies possess cold gas (HI, CO) and optical emission lines
(Halpha), supporting the presence of gas cooler than 10E4 K. The 60um to 100um
flux ratios imply a median dust temperature for the sample of 30 K, with a
range of 23-38 K.
These detections define the upper envelope of the optical to far-infrared
relationship, F_fir propto F_B^0.24+/-0.08, showing that optically bright
objects are also brighter in the infrared, although with considerable
dispersion. A luminosity correlation is present with L_fir propto
L_B^1.65+/-0.28, but the dust temperature is uncorrelated with luminosity.
Models that contain large dust grains composed of amorphous carbon plus
silicates come close to reproducing the typical 60um to 100um flux ratios, the
far-infrared luminosity, and the L_fir - L_B relationship.Comment: 10 postscript pages, 2 tables, and 2 figure
Non-existence of Skyrmion-Skyrmion and Skyrmion-anti-Skyrmion static equilibria
We consider classical static Skyrmion-anti-Skyrmion and Skyrmion-Skyrmion
configurations, symmetric with respect to a reflection plane, or symmetric up
to a -parity transformation respectively. We show that the stress tensor
component completely normal to the reflection plane, and hence its integral
over the plane, is negative definite or positive definite respectively.
Classical Skyrmions always repel classical Skyrmions and classical Skyrmions
always attract classical anti-Skyrmions and thus no static equilibrium, whether
stable or unstable, is possible in either case. No other symmetry assumption is
made and so our results also apply to multi-Skyrmion configurations. Our
results are consistent with existing analyses of Skyrmion forces at large
separation, and with numerical results on Skymion-anti-Skyrmion configurations
in the literature which admit a different reflection symmetry. They also hold
for the massive Skyrme model. We also point out that reflection symmetric
self-gravitating Skyrmions or black holes with Skyrmion hair cannot rest in
symmetric equilibrium with self-gravitating anti-Skyrmions.Comment: v2 Typos corrected, refs added. v3 Journal versio
Exercise interventions for preventing dementia or delaying cognitive decline in people with mild cognitive impairment
This is the protocol for a review and there is no abstract. The objectives are as follows: To evaluate the effects of exercise interventions for preventing dementia in people with mild cognitive impairment. We refer to Forbes 2015b and Forbes 2015c for the review protocols on exercise interventions for maintaining cognitive function in cognitively healthy people in mid and late life
Exercise interventions for maintaining cognitive function in cognitively healthy people in mid life
This is the protocol for a review and there is no abstract. The objectives are as follows: To evaluate the effects ofexercise interventions on cognitive function in cognitively healthy people in mid life. We refer to Forbes 2015b for the review protocol on Exercise interventions for maintaining cognitive function in cognitively healthy people in late life and to Forbes 2015c for the review protocol on Exercise interventions for prevention of dementia in people with mild cognitive impairment
Exercise interventions for maintaining cognitive function in cognitively healthy people in late life
This is the protocol for a review and there is no abstract. The objectives are as follows: To evaluate the effects ofexercise interventions on cognitive function in cognitively healthy people in late life. We refer to Forbes 2015b for the review on Exercise interventions for maintaining cognitive function in cognitively healthy people in mid life, and to Forbes 2015c for the review on Exercise interventions for prevention of dementia in people with mild cognitive impairment
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