11,879 research outputs found
Autism-associated SNPs in the clock genes _npas2_, _per1_ and the homeobox gene _en2_ alter DNA sequences that show characteristics of microRNA genes.
Intronic single nucleotide polymorphisms (SNPs) in the clock genes _npas2_ and _per1_ and the homeobox gene _en2_ are reported to be associated with autism. This bioinformatics analysis of the intronic regions which contain the autism-associated SNPs rs1861972 and rs1861973 in _en2_, rs1811399 in _npas2_, and rs885747 in _per1_, shows that these regions encode RNA transcripts with predicted structural characteristics of microRNAs. These microRNA-like structures are disrupted _in silico_ by the presence of the autism enriched alleles of rs1861972, rs1861973, rs1811399 and rs885747 specifically, as compared with the minor alleles of these SNPs. The predicted gene targets of these microRNA-like structures include genes reported to be implicated in autism (_gabrb3_, _shank3_) and genes causative of diseases co-morbid with autism (_mecp2_ and _rai1_). The inheritance of the AC haplotype of rs1861972 - rs1861973 in _en2_, the C allele of rs1811399 in _npas2_, and the C allele of rs1234747 in _per1_ may contribute to the causes of autism by affecting microRNA genes that are co-expressed along with the homeobox gene _en2_ and the circadian genes _npas2_ and _per1_
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Microgravimetric immunosensor for direct detection of aerosolized influenza A virus particles.
The development and characterization of a quartz crystal microbalance (QCM) sensor for the direct detection of aerosolized influenza A virions is reported. Self-assembled monolayers (SAMs) of mercaptoundecanoic acid (MUA) are formed on QCM gold electrodes to provide a surface amenable for the immobilization of anti-influenza A antibodies using NHS/EDC coupling chemistry. The surface-bound antibody provides a selective and specific sensing interface for the capture of influenza virions. A nebulizer is used to create aerosolized samples and is directly connected to a chamber housing the antibody-modified crystal ("immunochip"). Upon exposure to the aerosolized virus, the interaction between the antibody and virus leads to a dampening of the oscillation frequency of the quartz crystal. The magnitude of frequency change is directly related to virus concentration. Control experiments using aerosols from chicken egg allantoic fluid and an anti-murine antibody based immunosensor confirm that the observed signal originates from specific viral binding on the chip surface. Step-by-step surface modification of MUA assembly, antibody attachment, and antibody-virus interaction are characterized by atomic force microscopy (AFM) imaging analysis. Using the S/N = 3 principle, the limit of detection is estimated to be 4 virus particles/mL. The high sensitivity and real-time sensing scheme presented here can play an important role in the public health arena by offering a new analytical tool for identifying bio-contaminated areas and assisting in timely patient diagnosis
Disease Risks Associated with Increasing Feral Swine Numbers and Distribution in the United States
Feral hogs or âwild boarsâ come from several sources and include released or escaped domestic swine and the truly wild European boar. When free-roaming in North America, all are included in the term âferal swine,â as are hybrids of the two types. Although morphologically distinct, both the feral swine and European wild swine are recognized as Sus scrofa. The physical damage caused by feral swine has been well documented and includes damage to vehicles, vineyards, tree plantings, archaeological sites, agricultural crops, turf, soils, rare plant communities, and wildlife habitat (Seward et al. 2004). In addition they compete with livestock and native wildlife for food resources; prey on domestic animals and wildlife; and carry diseases that affect pets, livestock, wildlife and people (Seward et al. 2004). Texas, the state with the largest feral hog population, reports the annual damage to agriculture at 800 million annually (Pimentel et al. 2000). This estimate is approximate, and probably conservative, because environmental damage costs attributable to feral swine are not easily quantified nor are the costs of potential disease outbreaks
Rapid radiative clearing of protoplanetary discs
The lack of observed transition discs with inner gas holes of radii greater
than ~50AU implies that protoplanetary discs dispersed from the inside out must
remove gas from the outer regions rapidly. We investigate the role of
photoevaporation in the final clearing of gas from low mass discs with inner
holes. In particular, we study the so-called "thermal sweeping" mechanism which
results in rapid clearing of the disc. Thermal sweeping was originally thought
to arise when the radial and vertical pressure scale lengths at the X-ray
heated inner edge of the disc match. We demonstrate that this criterion is not
fundamental. Rather, thermal sweeping occurs when the pressure maximum at the
inner edge of the dust heated disc falls below the maximum possible pressure of
X-ray heated gas (which depends on the local X-ray flux). We derive new
critical peak volume and surface density estimates for rapid radiative clearing
which, in general, result in rapid dispersal happening less readily than in
previous estimates. This less efficient clearing of discs by X-ray driven
thermal sweeping leaves open the issue of what mechanism can clear gas from the
outer disc sufficiently quickly to explain the non-detection of cold gas around
weak line T Tauri stars.Comment: 13 pages, Accepted for publication in MNRA
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Harmonization of space-borne infra-red sensors measuring sea surface temperature
Sea surface temperature (SST) is observed by a constellation of sensors, and SST retrievals
are commonly combined into gridded SST analyses and climate data records (CDRs). Differential
biases between SSTs from different sensors cause errors in such products, including feature artefacts.
We introduce a new method for reducing differential biases across the SST constellation, by reconciling
the brightness temperature (BT) calibration and SST retrieval parameters between sensors. We use the
Advanced Along-Track Scanning Radiometer (AATSR) and the Sea and Land Surface Temperature
Radiometer (SLSTR) as reference sensors, and the Advanced Very High Resolution Radiometer
(AVHRR) of the MetOp-A mission to bridge the gap between these references. Observations across a
range of AVHRR zenith angles are matched with dual-view three-channel skin SST retrievals from
the AATSR and SLSTR. These skin SSTs act as the harmonization reference for AVHRR retrievals
by optimal estimation (OE). Parameters for the harmonized AVHRR OE are iteratively determined,
including BT bias corrections and observation error covariance matrices as functions of water-vapor
path. The OE SSTs obtained from AVHRR are shown to be closely consistent with the reference sensor
SSTs. Independent validation against drifting buoy SSTs shows that the AVHRR OE retrieval is stable
across the reference-sensor gap. We discuss that this method is suitable to improve consistency across
the whole constellation of SST sensors. The approach will help stabilize and reduce errors in future
SST CDRs, as well as having application to other domains of remote sensing
Lattice QCD Evidence that the Lambda(1405) Resonance is an Antikaon-Nucleon Molecule
For almost 50 years the structure of the Lambda(1405) resonance has been a
mystery. Even though it contains a heavy strange quark and has odd parity, its
mass is lower than any other excited spin-1/2 baryon. Dalitz and co-workers
speculated that it might be a molecular state of an antikaon bound to a
nucleon. However, a standard quark-model structure is also admissible. Although
the intervening years have seen considerable effort, there has been no
convincing resolution. Here we present a new lattice QCD simulation showing
that the strange magnetic form factor of the Lambda(1405) vanishes, signaling
the formation of an antikaon-nucleon molecule. Together with a Hamiltonian
effective-field-theory model analysis of the lattice QCD energy levels, this
strongly suggests that the structure is dominated by a bound antikaon-nucleon
component. This result clarifies that not all states occurring in nature can be
described within a simple quark model framework and points to the existence of
exotic molecular meson-nucleon bound states.Comment: Manuscript accepted for publication. 4 figures, 5 page
Recent and Long-Term Behavior of the Brawley Fault Zone, Imperial Valley, California: An Escalation in Slip Rate?
The Brawley fault zone (bfz) and the Brawley Seismic Zone constitute the principal transfer zone accommodating strain between the San Andreas and Imperial faults in southernmost California. The bfz ruptured along with the Imperial fault in the 1940 M_w 6.9 and the 1979 M_w 6.4 earthquakes, although in each case only minor slip apparently occurred on the bfz; several other episodes of slip and creep have been documented on the bfz historically. Until this study, it has been unclear whether the past few decades reflect average behavior of the fault. Two trenches were opened and a series of auger holes were bored across three strands of the bfz at Harris Road to compare the amount of slip observed historically with the displacements observed in the paleoseismic record. Evidence is presented, across the westernmost strand of the bfz and across the entire bfz at Harris Road, to show that both the average vertical slip rate observed in modern times (since 1970) and the vertical creep rate (excluding coseismic slip) observed during the 1970s are significantly higher than the long-term average. Across the westernmost strand, the long- term vertical rate is 1.2 (+1.5/â0.5) mm/yr, and the average rate since about a.d. 1710 is determined to be no greater than 2.0 mm/yr; in contrast, the average vertical rate between 1970 and 2004 across that strand was at least 4.3 mm/yr, and the 1970s vertical aseismic creep rate was 10 mm/yr. Likewise, across the entire bfz, the long- term vertical rate is 2.8 (+4.1/â1.4) mm/yr, whereas the rate between 1970 and 2004 was at least 7.2 mm/yr, and the 1970s aseismic creep rate was 10 mm/yr. The long-term strike-slip rate cannot be determined across any strands of the bfz but may be significant. In contrast to the commonly accepted higher sedimentation rates inferred for the entire Imperial Valley, we find that the average sedimentation rate on the downthrown side of the bfz adjacent to Mesquite Basin, in the millennium preceding the onset of agricultural influences, was at most 3.5 mm/yr. Finally, a creep event occurred on the bfz during our study in 2002 and is documented herein
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