34 research outputs found
Effects of kinetics of light-induced stomatal responses on photosynthesis and water-use efficiency
Both photosynthesis (A) and stomatal conductance (g s ) respond to changing irradiance, yet stomatal responses are an order of magnitude slower than photosynthesis, resulting in noncoordination between A and g s in dynamic light environments. Infrared gas exchange analysis was used to examine the temporal responses and coordination of A and g s to a step increase and decrease in light in a range of different species, and the impact on intrinsic water use efficiency was evaluated. The temporal responses revealed a large range of strategies to save water or maximize photosynthesis in the different species used in this study but also displayed an uncoupling of A and g s in most of the species. The shape of the guard cells influenced the rapidity of response and the overall g s values achieved, with different impacts on A and W i . The rapidity of g s in dumbbell-shaped guard cells could be attributed to size, whilst in elliptical-shaped guard cells features other than anatomy were more important for kinetics. Our findings suggest significant variation in the rapidity of stomatal responses amongst species, providing a novel target for improving photosynthesis and water use
A combined low-radio frequency/X-ray study of galaxy groups I. Giant Metrewave Radio Telescope observations at 235 MHz and 610 MHz
We present new Giant Metrewave Radio Telescope observations at 235 MHz and
610 MHz of 18 X-ray bright galaxy groups. These observations are part of an
extended project, presented here and in future papers, which combines
low-frequency radio and X-ray data to investigate the interaction between
central active galactic nuclei (AGN) and the intra-group medium (IGM). The
radio images show a very diverse population of group-central radio sources,
varying widely in size, power, morphology and spectral index. Comparison of the
radio images with Chandra and XMM-Newton X-ray images shows that groups with
significant substructure in the X-ray band and marginal radio emission at >= 1
GHz host low-frequency radio structures that correlate with substructures in
IGM. Radio-filled X-ray cavities, the most evident form of AGN/IGM interaction
in our sample, are found in half of the systems, and are typically associated
with small, low- or mid-power double radio sources. Two systems, NGC5044 and
NGC4636, possess multiple cavities, which are isotropically distributed around
the group center, possibly due to group weather. In other systems the
radio/X-ray correlations are less evident. However, the AGN/IGM interaction can
manifest itself through the effects of the high-pressure medium on the
morphology, spectral properties and evolution of the radio-emitting plasma. In
particular, the IGM can confine fading radio lobes in old/dying radio galaxies
and prevent them from dissipating quickly. Evidence for radio emission produced
by former outbursts that coexist with current activity is found in six groups
of the sample.Comment: Accepted for publication in the Astrophysical Journal Supplement
Series, 26 pages, 18 figures. A version with high-quality figures is
http://www.astro.umd.edu/~simona/giacintucci_hr.pd
The Baryon Oscillation Spectroscopic Survey of SDSS-III
The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the
scale of baryon acoustic oscillations (BAO) in the clustering of matter over a
larger volume than the combined efforts of all previous spectroscopic surveys
of large scale structure. BOSS uses 1.5 million luminous galaxies as faint as
i=19.9 over 10,000 square degrees to measure BAO to redshifts z<0.7.
Observations of neutral hydrogen in the Lyman alpha forest in more than 150,000
quasar spectra (g<22) will constrain BAO over the redshift range 2.15<z<3.5.
Early results from BOSS include the first detection of the large-scale
three-dimensional clustering of the Lyman alpha forest and a strong detection
from the Data Release 9 data set of the BAO in the clustering of massive
galaxies at an effective redshift z = 0.57. We project that BOSS will yield
measurements of the angular diameter distance D_A to an accuracy of 1.0% at
redshifts z=0.3 and z=0.57 and measurements of H(z) to 1.8% and 1.7% at the
same redshifts. Forecasts for Lyman alpha forest constraints predict a
measurement of an overall dilation factor that scales the highly degenerate
D_A(z) and H^{-1}(z) parameters to an accuracy of 1.9% at z~2.5 when the survey
is complete. Here, we provide an overview of the selection of spectroscopic
targets, planning of observations, and analysis of data and data quality of
BOSS.Comment: 49 pages, 16 figures, accepted by A
The Spitzer survey of interstellar clouds in the Gould Belt. II. The Cepheus Flare observed with IRAC and MIPS
We present Spitzer IRAC (~2 deg^2) and MIPS (~8 deg^2) observations of the
Cepheus Flare which is associated with the Gould Belt, at an approximate
distance of ~300 pc. Around 6500 sources are detected in all four IRAC bands,
of which ~900 have MIPS 24 micron detections. We identify 133 YSO candidates
using color-magnitude diagram techniques, a large number of the YSO candidates
are associated with the NGC 7023 reflection nebula. Cross identifications were
made with the Guide Star Catalog II and the IRAS Faint Source Catalog, and
spectral energy distributions (SED) were constructed. SED modeling was
conducted to estimate the degree of infrared excess. It was found that a large
majority of disks were optically thick accreting disks, suggesting that there
has been little disk evolution in these sources. Nearest-neighbor clustering
analysis identified four small protostellar groups (L1228, L1228N, L1251A, and
L1251B) with 5-15 members each and the larger NGC 7023 association with 32 YSO
members. The star formation efficiency for cores with clusters of protostars
and for those without clusters was found to be ~8% and ~1% respectively. The
cores L1155, L1241, and L1247 are confirmed to be starless down to our
luminosity limit of L_bol=0.06 L_sol.Comment: Submitted to ApJSS. 20 figures, 110 page
The Baryon Oscillation Spectroscopic Survey of SDSS-III
The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of large-scale structure. BOSS uses 1.5 million luminous galaxies as faint as i = 19.9 over 10,000 deg(2) to measure BAO to redshifts z < 0.7. Observations of neutral hydrogen in the Ly alpha forest in more than 150,000 quasar spectra (g < 22) will constrain BAO over the redshift range 2.15 < z < 3.5. Early results from BOSS include the first detection of the large-scale three-dimensional clustering of the Ly alpha forest and a strong detection from the Data Release 9 data set of the BAO in the clustering of massive galaxies at an effective redshift z = 0.57. We project that BOSS will yield measurements of the angular diameter distance d(A) to an accuracy of 1.0% at redshifts z = 0.3 and z = 0.57 and measurements of H(z) to 1.8% and 1.7% at the same redshifts. Forecasts for Ly alpha forest constraints predict a measurement of an overall dilation factor that scales the highly degenerate D-A(z) and H-1(z) parameters to an accuracy of 1.9% at z similar to 2.5 when the survey is complete. Here, we provide an overview of the selection of spectroscopic targets, planning of observations, and analysis of data and data quality of BOSS
Non-surgical Intratracheal Instillation of Mice with Analysis of Lungs and Lung Draining Lymph Nodes by Flow Cytometry
A study of embodiment of force schema: focusing on the hand gestures of participants in the TV debate program
Brain aromatase overexpression does not reduce ischaemic damage nor improve long term functional outcome after experimental stroke: A magnetic resonance imaging and behavioural study
The Immature Fiber Mutant Phenotype of Cotton (Gossypium hirsutum) Is Linked to a 22-bp Frame-Shift Deletion in a Mitochondria Targeted Pentatricopeptide Repeat Gene
Cotton seed trichomes are the most important source of natural fibers globally. The major fiber thickness properties influence the price of the raw material, and the quality of the finished product. The recessive immature fiber (im) gene reduces the degree of fiber cell wall thickening by a process that was previously shown to involve mitochondrial function in allotetraploid Gossypium hirsutum. Here, we present the fine genetic mapping of the im locus, gene expression analysis of annotated proteins near the locus, and association analysis of the linked markers. Mapping-by-sequencing identified a 22-bp deletion in a pentatricopeptide repeat (PPR) gene that is completely linked to the immature fiber phenotype in 2837 F2 plants, and is absent from all 163 cultivated varieties tested, although other closely linked marker polymorphisms are prevalent in the diversity panel. This frame-shift mutation results in a transcript with two long open reading frames: one containing the N-terminal transit peptide that targets mitochondria, the other containing only the RNA-binding PPR domains, suggesting that a functional PPR protein cannot be targeted to mitochondria in the im mutant. Taken together, these results suggest that PPR gene Gh_A03G0489 is involved in the cotton fiber wall thickening process, and is a promising candidate gene at the im locus. Our findings expand our understanding of the molecular mechanisms that modulate cotton fiber fineness and maturity, and may facilitate the development of cotton varieties with superior fiber attributes