429 research outputs found
To Avoid or Not to Avoid? Factors Influencing the Discrimination or Predator Diet Cues by a Terrestrial Salamander
Many prey species use chemical cues deposited by predators to assess predation risk, and some prey are capable of discriminating among predator chemical traces based on the predatorâs recent diet. Here we test the inïŹuence of genetic relatedness (degree of genetic similarity between prey) and ecological relatedness (degree of refuge and trophic overlap between syntopic prey) on the evolution of predator-diet discrimination by red-backed salamanders, Plethodon cinereus. In experiment 1, we examined whether red-backed salamanders from Binghamton University (Binghamton, New York, U.S.A.) would differentially respond to chemical traces from garter snakes (Thamnophis sirtalis) fed conspeciïŹc P. cinereus from four populations belonging to three phylogenetic groups: Group II from Mountain Lake, Virginia, Group III from Binghamton University, New York, Group III from Hawk Mountain, Pennsylvania, and Group IV from Cherry Springs, Pennsylvania, U.S.A. The test salamanders only avoided chemical traces from garter snakes fed salamanders from the two Group III sites, although the response to the Group III-Hawk Mountain treatment was intermediate to that for the Group III-Binghamton University treatment and the Group II and IV treatments. In experiment 2, we examined whether red-backed salamanders collected from two subpopulations, syntopic or allotopic with two-lined salamanders, Eurycea bislineata, vary in their response to chemical cues from garter snakes foraging on two-lined salamanders. Only red-backed salamanders syntopic with E. bislineata avoided chemical traces from garter snakes fed E. bislineata. These results suggest that both genetic and ecological relatedness play a role in the evolution of predator-diet discrimination in red-backed salamanders
Considerations with using unmanned aircraft systems in turfgrass
In recent years, small unmanned aircraft systems (sUAS) and advancements in remote sensing technology have provided alternative and more affordable means for monitoring crop health and stress than ground-based (hand-held or vehicle-mounted) or other aerial-based platforms (manned aircraft or satellites). However, few scientific studies have evaluated the application of sUAS in turfgrass systems. The use of sUAS in monitoring turfgrass requires an understanding of basic remote sensing principles; identifying the target of interest and the various sUAS platforms and sensors that provide the necessary resolution and frequencies to measure and monitor that target; calibration of sensors in the field; and data processing considerations. Those topics are discussed, followed by reviews of recent turfgrass field studies conducted to predict and manage drought stress and pest outbreaks, and improve phenotyping capabilities in turfgrass breeding programs. The use of sUAS remote sensing in turfgrass offers unique possibilities and challenges, which are addressed herein
Academic self-concept, gender and single-sex schooling
This paper assesses gender differences in academic self-concept for a cohort of children born in 1958 (the National Child Development Study). We address the question of whether attending single-sex or co-educational schools affected studentsâ perceptions of their own academic abilities (academic self-concept). Academic selfconcept was found to be highly gendered, even controlling for prior test scores. Boys had higher self-concepts in maths and science, and girls in English. Single-sex schooling reduced the gender gap in self-concept, while selective schooling was linked to lower academic self-concept overall
Phenotype and envelope gene diversity of nef-deleted HIV-1 isolated from long-term survivors infected from a single source
<p>Abstract</p> <p>Background</p> <p>The Sydney blood bank cohort (SBBC) of long-term survivors consists of multiple individuals infected with attenuated, <it>nef</it>-deleted variants of human immunodeficiency virus type 1 (HIV-1) acquired from a single source. Long-term prospective studies have demonstrated that the SBBC now comprises slow progressors (SP) as well as long-term nonprogressors (LTNP). Convergent evolution of <it>nef </it>sequences in SBBC SP and LTNP indicates the <it>in vivo </it>pathogenicity of HIV-1 in SBBC members is dictated by factors other than <it>nef</it>. To better understand mechanisms underlying the pathogenicity of <it>nef</it>-deleted HIV-1, we examined the phenotype and <it>env </it>sequence diversity of sequentially isolated viruses (n = 2) from 3 SBBC members.</p> <p>Results</p> <p>The viruses characterized here were isolated from two SP spanning a three or six year period during progressive HIV-1 infection (subjects D36 and C98, respectively) and from a LTNP spanning a two year period during asymptomatic, nonprogressive infection (subject C18). Both isolates from D36 were R5X4 phenotype and, compared to control HIV-1 strains, replicated to low levels in peripheral blood mononuclear cells (PBMC). In contrast, both isolates from C98 and C18 were CCR5-restricted. Both viruses isolated from C98 replicated to barely detectable levels in PBMC, whereas both viruses isolated from C18 replicated to low levels, similar to those isolated from D36. Analysis of <it>env </it>by V1V2 and V3 heteroduplex tracking assay, V1V2 length polymorphisms, sequencing and phylogenetic analysis showed distinct intra- and inter-patient <it>env </it>evolution.</p> <p>Conclusion</p> <p>Independent evolution of <it>env </it>despite convergent evolution of <it>nef </it>may contribute to the <it>in vivo </it>pathogenicity of <it>nef</it>-deleted HIV-1 in SBBC members, which may not necessarily be associated with changes in replication capacity or viral coreceptor specificity.</p
Pathogenicity and immunogenicity of attenuated, nef-deleted HIV-1 strains in vivo
In efforts to develop an effective vaccine, sterilizing immunity to primate lentiviruses has only been achieved by the use of live attenuated viruses carrying major deletions in nef and other accessory genes. Although live attenuated HIV vaccines are unlikely to be developed due to a myriad of safety concerns, opportunities exist to better understand the correlates of immune protection against HIV infection by studying rare cohorts of long-term survivors infected with attenuated, nef-deleted HIV strains such as the Sydney blood bank cohort (SBBC). Here, we review studies of viral evolution, pathogenicity, and immune responses to HIV infection in SBBC members. The studies show that potent, broadly neutralizing anti-HIV antibodies and robust CD8+ T-cell responses to HIV infection were not necessary for long-term control of HIV infection in a subset of SBBC members, and were not sufficient to prevent HIV sequence evolution, augmentation of pathogenicity and eventual progression of HIV infection in another subset. However, a persistent T-helper proliferative response to HIV p24 antigen was associated with long-term control of infection. Together, these results underscore the importance of the host in the eventual outcome of infection. Thus, whilst generating an effective antibody and CD8+ T-cell response are an essential component of vaccines aimed at preventing primary HIV infection, T-helper responses may be important in the generation of an effective therapeutic vaccine aimed at blunting chronic HIV infection
PTF10fqs: A Luminous Red Nova in the Spiral Galaxy Messier 99
The Palomar Transient Factory (PTF) is systematically charting the optical
transient and variable sky. A primary science driver of PTF is building a
complete inventory of transients in the local Universe (distance less than 200
Mpc). Here, we report the discovery of PTF10fqs, a transient in the luminosity
"gap" between novae and supernovae. Located on a spiral arm of Messier 99, PTF
10fqs has a peak luminosity of Mr = -12.3, red color (g-r = 1.0) and is slowly
evolving (decayed by 1 mag in 68 days). It has a spectrum dominated by
intermediate-width H (930 km/s) and narrow calcium emission lines. The
explosion signature (the light curve and spectra) is overall similar to thatof
M85OT2006-1, SN2008S, and NGC300OT. The origin of these events is shrouded in
mystery and controversy (and in some cases, in dust). PTF10fqs shows some
evidence of a broad feature (around 8600A) that may suggest very large
velocities (10,000 km/s) in this explosion. Ongoing surveys can be expected to
find a few such events per year. Sensitive spectroscopy, infrared monitoring
and statistics (e.g. disk versus bulge) will eventually make it possible for
astronomers to unravel the nature of these mysterious explosions.Comment: 12 pages, 12 figures, Replaced with published versio
The infrared supernova rate in starburst galaxies
We report the results of our ongoing search for extincted supernovae (SNe) at
near-infrared wavelengths. We have monitored at 2.2 micron a sample of 46
Luminous Infrared Galaxies and detected 4 SNe. The number of detections is
still small but sufficient to provide the first estimate of supernova rate at
near-infrared wavelengths. We measure a SN rate ofv 7.6+/-3.8 SNu which is an
order of magnitude larger than observed in quiescent galaxies. On the other
hand, the observed near-infrared rate is still a factor 3-10 smaller than that
estimated from the far-infrared luminosity of the galaxies. Among various
possibilities, the most likely scenario is that dust extinction is so high
(Av>30) to obscure most SNe even in the near-IR.
The role of type Ia SNe is also discussed within this context. We derive the
type Ia SN rate as a function of the stellar mass of the galaxy and find a
sharp increase toward galaxies with higher activity of star formation. This
suggests that a significant fraction of type Ia SNe are associated with young
stellar populations.
Finally, as a by-product, we give the average K-band light curve of
core-collapse SNe based on all the existing data, and review the relation
between SN rate and far-infrared luminosity.Comment: A&A, in press, 13 page
Genome-wide analyses for personality traits identify six genomic loci and show correlations with psychiatric disorders
Personality is influenced by genetic and environmental factors1
and associated with mental health. However, the underlying
genetic determinants are largely unknown. We identified six
genetic loci, including five novel loci2,3, significantly associated
with personality traits in a meta-analysis of genome-wide
association studies (N = 123,132â260,861). Of these genomewide
significant loci, extraversion was associated with variants
in WSCD2 and near PCDH15, and neuroticism with variants
on chromosome 8p23.1 and in L3MBTL2. We performed a
principal component analysis to extract major dimensions
underlying genetic variations among five personality traits
and six psychiatric disorders (N = 5,422â18,759). The first
genetic dimension separated personality traits and psychiatric
disorders, except that neuroticism and openness to experience
were clustered with the disorders. High genetic correlations
were found between extraversion and attention-deficitâ
hyperactivity disorder (ADHD) and between openness and
schizophrenia and bipolar disorder. The second genetic
dimension was closely aligned with extraversionâintroversion
and grouped neuroticism with internalizing psychopathology
(e.g., depression or anxiety)
Determining Star Formation Rates for Infrared Galaxies
We show that measures of star formation rates (SFRs) for infrared galaxies
using either single-band 24 um or extinction-corrected Paschen-alpha
luminosities are consistent in the total infrared luminosity = L(TIR) ~ 10^10
L_sun range. MIPS 24 micron photometry can yield star formation rates
accurately from this luminosity upward: SFR(M_sun/yr) = 7.8 x 10^-10 L(24 um,
L_sun) from L(TIR) = 5 x 10^9 L_sun to 10^11 L_sun, and SFR = 7.8 x 10^-10 L(24
um, L_sun) x (7.76 x 10^-11 L(24))^0.048 for higher L(TIR). For galaxies with
L(TIR) >= 10^10 L_sun, these new expressions should provide SFRs to within 0.2
dex. For L(TIR) >= 10^11 L_sun, we find that the SFR of infrared galaxies is
significantly underestimated using extinction-corrected Pa-alpha (and
presumably using any other optical or near infrared recombination lines). As a
part of this work, we constructed spectral energy distribution (SED) templates
for eleven luminous and ultraluminous purely star forming infrared galaxies
(LIRGs and ULIRGs) and over the spectral range 0.4 microns to 30 cm. We use
these templates and the SINGS data to construct average templates from 5
microns to 30 cm for infrared galaxies with L(TIR) = 5 x 10^9 to 10^13 L_sun.
All of these templates are made available on line.Comment: Accepted by ApJ. Revised in proof to strengthen caveats about the
extrapolation of these IR templates above L(TIR)>2e12, without suitable local
purely starforming template galaxies above this luminosity. Source includes
two machine-readable tables of template spectra SEDs, or download the tables
from http://mingus.as.arizona.edu/~bjw/ir_templates
A Deep Halpha Survey of Galaxies in the Two Nearby Clusters Abell1367 and Coma: The Halpha Luminosity Functions
We present a deep wide field Halpha imaging survey of the central regions of
the two nearby clusters of galaxies Coma and Abell1367, taken with the WFC at
the INT2.5m telescope. We determine for the first time the Schechter parameters
of the Halpha luminosity function (LF) of cluster galaxies. The Halpha LFs of
Abell1367 and Coma are compared with each other and with that of Virgo,
estimated using the B band LF by Sandage et al. (1985) and a L(Halpha) vs M_B
relation. Typical parameters of phi^* ~ 10^0.00+-0.07 Mpc^-3, L^* ~ 10^41.25+-
0.05 erg sec^-1 and alpha ~ -0.70+-0.10 are found for the three clusters. The
best fitting parameters of the cluster LFs differ from those found for field
galaxies, showing flatter slopes and lower scaling luminosities L^*. Since,
however, our Halpha survey is significantly deeper than those of field
galaxies, this result must be confirmed on similarly deep measurements of field
galaxies. By computing the total SFR per unit volume of cluster galaxies, and
taking into account the cluster density in the local Universe, we estimate that
the contribution of clusters like Coma and Abell1367 is approximately 0.25% of
the SFR per unit volume of the local Universe.Comment: 19 pages, 11 figures, accepted for publication in A&
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