6,998 research outputs found
Structural Changes in U.S. Agricultural Production and Productivity
Livestock Production/Industries,
Staphylococcus aureus Biofilm and Planktonic cultures differentially impact gene expression, mapk phosphorylation, and cytokine production in human keratinocytes
<p>Abstract</p> <p>Background</p> <p>Many chronic diseases, such as non-healing wounds are characterized by prolonged inflammation and respond poorly to conventional treatment. Bacterial biofilms are a major impediment to wound healing. Persistent infection of the skin allows the formation of complex bacterial communities termed biofilm. Bacteria living in biofilms are phenotypically distinct from their planktonic counterparts and are orders of magnitude more resistant to antibiotics, host immune response, and environmental stress. <it>Staphylococcus aureus </it>is prevalent in cutaneous infections such as chronic wounds and is an important human pathogen.</p> <p>Results</p> <p>The impact of <it>S. aureus </it>soluble products in biofilm-conditioned medium (BCM) or in planktonic-conditioned medium (PCM) on human keratinocytes was investigated. Proteomic analysis of BCM and PCM revealed differential protein compositions with PCM containing several enzymes involved in glycolysis. Global gene expression of keratinocytes exposed to biofilm and planktonic <it>S. aureus </it>was analyzed after four hours of exposure. Gene ontology terms associated with responses to bacteria, inflammation, apoptosis, chemotaxis, and signal transduction were enriched in BCM treated keratinocytes. Several transcripts encoding cytokines were also upregulated by BCM after four hours. ELISA analysis of cytokines confirmed microarray results at four hours and revealed that after 24 hours of exposure, <it>S. aureus </it>biofilm induced sustained low level cytokine production compared to near exponential increases of cytokines in planktonic treated keratinocytes. The reduction in cytokines produced by keratinocytes exposed to biofilm was accompanied by suppressed phosphorylation of MAPKs. Chemical inhibition of MAPKs did not drastically reduce cytokine production in BCM-treated keratinocytes suggesting that the majority of cytokine production is mediated through MAPK-independent mechanisms.</p> <p>Conclusions</p> <p>Collectively the results indicate that <it>S. aureus </it>biofilms induce a distinct inflammatory response compared to their planktonic counterparts. The differential gene expression and production of inflammatory cytokines by biofilm and planktonic cultures in keratinocytes could have implications for the formation and persistence of chronic wounds. The formation of a biofilm should be considered in any study investigating host response to bacteria.</p
The X-Ray Concentration-Virial Mass Relation
We present the concentration (c)-virial mass (M) relation of 39 galaxy
systems ranging in mass from individual early-type galaxies up to the most
massive galaxy clusters, (0.06-20) x 10^{14} M_sun. We selected for analysis
the most relaxed systems possessing the highest quality data currently
available in the Chandra and XMM public data archives. A power-law model fitted
to the X-ray c-M relation requires at high significance (6.6 sigma) that c
decreases with increasing M, which is a general feature of CDM models. The
median and scatter of the c-M relation produced by the flat, concordance LCDM
model (Omega_m=0.3, sigma_8=0.9) agrees with the X-ray data provided the sample
is comprised of the most relaxed, early forming systems, which is consistent
with our selection criteria. Holding the rest of the cosmological parameters
fixed to those in the concordance model the c-M relation requires 0.76< sigma_8
<1.07 (99% conf.), assuming a 10% upward bias in the concentrations for early
forming systems. The tilted, low-sigma_8 model suggested by a new WMAP analysis
is rejected at 99.99% confidence, but a model with the same tilt and
normalization can be reconciled with the X-ray data by increasing the dark
energy equation of state parameter to w ~ -0.8. When imposing the additional
constraint of the tight relation between sigma_8 and Omega_m from studies of
cluster abundances, the X-ray c-M relation excludes (>99% conf.) both open CDM
models and flat CDM models with Omega_m ~1. This result provides novel evidence
for a flat, low-Omega_m universe with dark energy using observations only in
the local (z << 1) universe. Possible systematic errors in the X-ray mass
measurements of a magnitude ~10% suggested by CDM simulations do not change our
conclusions.Comment: Accepted for Publication in ApJ; 13 pages, 4 figures; minor
clarifications and updates; correlation coefficients corrected in Table 1
(correct values were used in the analysis in previous versions); conclusions
unchange
Ground Water in the Kentucky River Basin
Most private wells in the Kentucky River Basin are in unconfined or semi-confined bedrock aquifers. Within these aquifers, high-yield zones are irregularly distributed. The most productive wells are drilled into fractured bedrock and alluvium along the Kentucky River floodplain. The data indicate that ground water acts as a buffer to peak and low flows in Kentucky River Basin streams. At current withdrawal rates, ground-water usage does not seem to have an adverse impact on the Kentucky River. Privately owned ground-water sources supply approximately 135,000 people living in the basin-approximately 19 percent of the total population and 36 percent of the rural population. More than 50 percent of residential water supplies in eastern Kentucky rely on ground water. If aquifers are protected from pollution by wellhead protection programs and old wells are retrofitted to prevent direct contamination, then ground water will continue to provide a reliable water supply in many rural areas of the basin. However, for most of the basin, few wells will have yields adequate to supply a large demand. Ground water from present wells will not provide an adequate supply for communities with a population of over a few thousand. Limited discharge data available for springs and large wells in the basin strongly suggest that the potential for ground water to supplement current supplies should not be ignored. Discharge from well fields and springs could be used to augment surface supplies during drought. A better understanding of the distribution and quality of ground-water resources is crucial for the citizens of the basin to fully benefit from ground water
Structural Changes in U.S. Agricultural Production and Productivity
The structure of U.S. agricultural production changed dramatically during the 20th Century. Major technological innovations transformed the relationship between agricultural inputs and outputs, and contributed to rapid increases in agricultural productivity. However, evidence is mounting that suggests we have entered a new era, with substantially lower rates of productivity growth. In this article, we examine trends and spatial patterns in agricultural input use, production of outputs, and productivity. We focus on productivity growth over the period 1949–2002, and find a statistically significant slowdown in productivity growth after 1990
The NGC 7129 Young Stellar Cluster: A Combined Spitzer, MMT, and 2MASS Census of Disks, Protostars, and Outflows
We present the analysis of seven band (1.2 to 8 micron) ground and
space-based imaging of the NGC 7129 young stellar cluster from FLAMINGOS on
MMT, 2MASS, and the Infrared Array Camera (IRAC) on the Spitzer Space
Telescope. An analysis of the H-[4.5] vs. J-H colors reveals 84 objects with
circumstellar disks. Of these, 42 are located within the cluster core, a 0.5 pc
(100'') radius region of enhanced stellar surface density. From a luminosity
and extinction limited sample of the stars within the cluster core boundary we
have determined that 54% +/- 14% have circumstellar disks. Finally, we report
the detection of several resolved outflows in the IRAC 4.5 micron mosaic.Comment: 13 pages, 4 figures. Accepted to the Spitzer special issue of ApJS.
The full-resolution preprint can be obtained from
http://astro.pas.rochester.edu/~rguter/preprints/gutermuth_ngc7129_a.tar.g
The Absence of Adiabatic Contraction of the Radial Dark Matter Profile in the Galaxy Cluster A2589
We present an X-ray analysis of the radial mass profile of the radio-quiet
galaxy cluster A2589 between 0.015-0.25 r_vir using an XMM-Newton observation.
Except for a ~16 kpc shift of the X-ray center of the R=45-60 kpc annulus,
A2589 possesses a remarkably symmetrical X-ray image and is therefore an
exceptional candidate for precision studies of its mass profile by applying
hydrostatic equilibrium. The total gravitating matter profile is well described
by the NFW model (fractional residuals <~10%) with c_vir=6.1 +/- 0.3 and M_vir
= 3.3 +/- 0.3 x 10^{14} M_sun (r_vir = 1.74 +/- 0.05 Mpc) in excellent
agreement with LCDM. When the mass of the hot ICM is subtracted from the
gravitating matter profile, the NFW model fitted to the resulting dark matter
(DM) profile produces essentially the same result. However, if a component
accounting for the stellar mass (M_*) of the cD galaxy is included, then the
NFW fit to the DM profile is substantially degraded in the central r ~50 kpc
for reasonable M_*/L_V. Modifying the NFW DM halo by adiabatic contraction
arising from the early condensation of stellar baryons in the cD galaxy further
degrades the fit. The fit is improved substantially with a Sersic-like model
recently suggested by high resolution N-body simulations but with an inverse
Sersic index, alpha ~0.5, a factor of ~3 higher than predicted. We argue that
neither random turbulent motions nor magnetic fields can provide sufficient
non-thermal pressure support to reconcile the XMM mass profile with adiabatic
contraction of a CDM halo assuming reasonable M_*/L_V. Our results support the
scenario where, at least for galaxy clusters, processes during halo formation
counteract adiabatic contraction so that the total gravitating mass in the core
approximately follows the NFW profile.Comment: 15 pages, 11 figures, accepted for publication in ApJ. Minor changes
to match published versio
Probing the Dark Matter and Gas Fraction in Relaxed Galaxy Groups with X-ray observations from Chandra and XMM
We present radial mass profiles within 0.3 r_vir for 16 relaxed galaxy
groups-poor clusters (kT range 1-3 keV) selected for optimal mass constraints
from the Chandra and XMM data archives. After accounting for the mass of hot
gas, the resulting mass profiles are described well by a two-component model
consisting of dark matter (DM), represented by an NFW model, and stars from the
central galaxy. The stellar component is required only for 8 systems, for which
reasonable stellar mass-to-light ratios (M/L_K) are obtained, assuming a Kroupa
IMF. Modifying the NFW dark matter halo by adiabatic contraction does not
improve the fit and yields systematically lower M/L_K. In contrast to previous
results for massive clusters, we find that the NFW concentration parameter
(c_vir) for groups decreases with increasing M_vir and is inconsistent with no
variation at the 3 sigma level. The normalization and slope of the c_vir-M_vir
relation are consistent with the standard LambdaCDM cosmological model with
sigma_8 = 0.9. The small intrinsic scatter measured about the c_vir-M_vir
relation implies the groups represent preferentially relaxed, early forming
systems. The mean gas fraction (f =0.05 +/- 0.01) of the groups measured within
an overdensity Delta=2500 is lower than for hot, massive clusters, but the
fractional scatter (sigma_f/f=0.2) for groups is larger, implying a greater
impact of feedback processes on groups, as expected.Comment: Accepted for Publication in ApJ; 30 pages, 9 figures. No changes from
previous versio
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