3,632 research outputs found
Recommended from our members
Global analysis of gene expression reveals mRNA superinduction is required for the inducible immune response to a bacterial pathogen.
The inducible innate immune response to infection requires a concerted process of gene expression that is regulated at multiple levels. Most global analyses of the innate immune response have focused on transcription induced by defined immunostimulatory ligands, such as lipopolysaccharide. However, the response to pathogens involves additional complexity, as pathogens interfere with virtually every step of gene expression. How cells respond to pathogen-mediated disruption of gene expression to nevertheless initiate protective responses remains unclear. We previously discovered that a pathogen-mediated blockade of host protein synthesis provokes the production of specific pro-inflammatory cytokines. It remains unclear how these cytokines are produced despite the global pathogen-induced block of translation. We addressed this question by using parallel RNAseq and ribosome profiling to characterize the response of macrophages to infection with the intracellular bacterial pathogen Legionella pneumophila. Our results reveal that mRNA superinduction is required for the inducible immune response to a bacterial pathogen
Expected seismicity and the seismic noise environment of Europa
Seismic data will be a vital geophysical constraint on internal structure of
Europa if we land instruments on the surface. Quantifying expected seismic
activity on Europa both in terms of large, recognizable signals and ambient
background noise is important for understanding dynamics of the moon, as well
as interpretation of potential future data. Seismic energy sources will likely
include cracking in the ice shell and turbulent motion in the oceans. We define
a range of models of seismic activity in Europa's ice shell by assuming each
model follows a Gutenberg-Richter relationship with varying parameters. A range
of cumulative seismic moment release between and Nm/yr is
defined by scaling tidal dissipation energy to tectonic events on the Earth's
moon. Random catalogs are generated and used to create synthetic continuous
noise records through numerical wave propagation in thermodynamically
self-consistent models of the interior structure of Europa. Spectral
characteristics of the noise are calculated by determining probabilistic power
spectral densities of the synthetic records. While the range of seismicity
models predicts noise levels that vary by 80 dB, we show that most noise
estimates are below the self-noise floor of high-frequency geophones, but may
be recorded by more sensitive instruments. The largest expected signals exceed
background noise by 50 dB. Noise records may allow for constraints on
interior structure through autocorrelation. Models of seismic noise generated
by pressure variations at the base of the ice shell due to turbulent motions in
the subsurface ocean may also generate observable seismic noise.Comment: 24 pages, 11 figures, Added in supplementary information from
revision submission, including 3 audio files with sonification of Europa
noise records. To view attachments, please download and extract the gzipped
tar source file listed under "Other formats
Modeling Disk Cracks in Rotors by Utilizing Speed Dependent Eccentricity
This paper discusses the feasibility of vibration-based structural health monitoring for detecting disk cracks in rotor systems. The approach of interest assumes that a crack located on a rotating disk causes a minute change in the system’s center of mass due to the centrifugal force induced opening of the crack. The center of mass shift is expected to reveal itself in the vibration vector (i.e., whirl response; plotted as amplitude and phase versus speed) gathered during a spin-up and/or spin-down test. Here, analysis is accomplished by modeling a Jeffcott rotor that is characterized by analytical, numerical, and experimental data. The model, which has speed dependent eccentricity, is employed in order to better understand the sensitivity of the approach. For the experimental set-up emulated here (i.e., a single disk located mid-span on a flexible shaft), it appears that a rather sizable flaw in the form of a through-thickness notch could be detected by monitoring the damage-induced shift in center of mass. Although, identifying actual disk cracks in complex “real world” environments, where noncritical crack lengths are small and excessive mechanical and/or electrical noise are present, would prove to be rather challenging. Further research is needed in this regard
Strange hyperon and antihyperon production from quark and string-rope matter
Hyperon and antihyperon production is investigated using two microscopical
models: {\bf (1)} the fast hadronization of quark matter as given by the ALCOR
model; {\bf (2)} string formation and fragmentation as in the HIJING/B model.
We calculate the particle numbers and momentum distributions for Pb+Pb
collisions at CERN SPS energies in order to compare the two models with each
other and with the available experimental data. We show that these two
theoretical approaches give similar yields for the hyperons, but strongly
differ for antihyperons.Comment: 11 pages, Latex, 3 EPS figures, contribution to the Proceedings of
the 4th International Conference on Strangeness in Quark Matter (SQM'98),
Padova, Italy, 20-24 July 199
The Effects of Acute Creatine Supplementation on Arterial Stiffness
Click the PDF icon to download the abstract
Anti-Hyperon Enhancement through Baryon Junction Loops
The baryon junction exchange mechanism recently proposed to explain valence
baryon number transport in nuclear collisions is extended to study midrapidity
anti-hyperon production. Baryon junction-anti-junction (J anti-J) loops are
shown to enhance anti-Lambda, anti-Xi, anti-Omega yields as well as lead to
long range rapidity correlations. Results are compared to recent WA97 Pb + Pb
-> Y + anti-Y + X data.Comment: 10 pages, 4 figure
Comparison of Fibroblast and Vascular Cell Adhesion to Nano-Structured Poly(lactic-co-glycolic acid) Films
Utilization of soil organic phosphorus as a strategic approach for sustainable agriculture
Soil organic phosphorus (P
org
) can significantly assist in minimizing the adverse effects of chemi-
cal phosphorus fertilizers on aquatic and marine resources. Success to achieve the desired last-
ing transformation is primarily reliant on the drastic reduction of wasteful applications of chemical
phosphorus fertilizers, thereby paving the way for proper investment of soil P
org
reserves. To this
end, organically-bound phosphorus can be viewed as a cornerstone for the future development
of agriculture. Thus, we consider it very timely to emphasize the suitability of soil P
org
to lead the
way
Recommended from our members
A 2000-year annual record of snow accumulation rates for Law Dome, East Antarctica
Accurate high-resolution records of snow accumulation rates in Antarctica are crucial for estimating ice sheet mass balance and subsequent sea level change. Snowfall rates at Law Dome, East Antarctica, have been linked with regional atmospheric circulation to the mid-latitudes as well as regional Antarctic snowfall. Here, we extend the length of the Law Dome accumulation record from 750 years to 2035 years, using recent annual layer dating that extends to 22 BCE. Accumulation rates were calculated as the ratio of measured to modelled layer thicknesses, multiplied by the long-term mean accumulation rate. The modelled layer thicknesses were based on a power-law vertical strain rate profile fitted to observed annual layer thickness. The periods 380–442, 727–783 and 1970–2009 CE have above-average snow accumulation rates, while 663–704, 933–975 and 1429–1468 CE were below average, and decadal-scale snow accumulation anomalies were found to be relatively common (74 events in the 2035-year record). The calculated snow accumulation rates show good correlation with atmospheric reanalysis estimates, and significant spatial correlation over a wide expanse of East Antarctica, demonstrating that the Law Dome record captures larger-scale variability across a large region of East Antarctica well beyond the immediate vicinity of the Law Dome summit. Spectral analysis reveals periodicities in the snow accumulation record which may be related to El Niño–Southern Oscillation (ENSO) and Interdecadal Pacific Oscillation (IPO) frequencies
Cryptic diversity of a widespread global pathogen reveals expanded threats to amphibian conservation
Biodiversity loss is one major outcome of human-mediated ecosystem disturbance. One way that humans have triggered wildlife declines is by transporting disease-causing agents to remote areas of the world. Amphibians have been hit particularly hard by disease due in part to a globally distributed pathogenic chytrid fungus (Batrachochytrium dendrobatidis [Bd]). Prior research has revealed important insights into the biology and distribution of Bd; however, there are still many outstanding questions in this system. Although we know that there are multiple divergent lineages of Bd that differ in pathogenicity, we know little about how these lineages are distributed around the world and where lineages may be coming into contact. Here, we implement a custom genotyping method for a global set of Bd samples. This method is optimized to amplify and sequence degraded DNA from noninvasive skin swab samples. We describe a divergent lineage of Bd, which we call BdASIA3, that appears to be widespread in Southeast Asia. This lineage co-occurs with the global panzootic lineage (BdGPL) in multiple localities. Additionally, we shed light on the global distribution of BdGPL and highlight the expanded range of another lineage, BdCAPE. Finally, we argue that more monitoring needs to take place where Bd lineages are coming into contact and where we know little about Bd lineage diversity. Monitoring need not use expensive or difficult field techniques but can use archived swab samples to further explore the history—and predict the future impacts—of this devastating pathogen
- …