273 research outputs found
Crop Insurance Changes in 2011
For a number of years the Risk Management Agency (RMA) of the United States Department of Agriculture (USDA) has been working with the crop insurance industry to streamline the crop insurance program for the major crops. The new Common Crop Insurance Policy, referred to as the COMBO Policy, is in effect beginning with crops harvested in 2011. Crops covered include corn, soybeans, grain sorghum, wheat, barley, cotton, rice, canola and sunflowers
Ca II triplet spectroscopy of small magellanic cloud red giants. II. abundances for a sample of field stars
We have obtained metallicities of ∼360 red giant stars distributed in 15 Small Magellanic Cloud (SMC) fields from near-infrared spectra covering the Ca II triplet lines using the VLT + FORS2. The errors of the derived [Fe/H] values range from 0.09 to 0.35 dex per star, with a mean of 0.17 dex. The metallicity distribution (MD) of the whole sample shows a mean value of [Fe/H] = -1.00 ± 0.02, with a dispersion of 0.32 0.01, in agreement with global mean [Fe/H] values found in previous studies. We find no evidence of a metallicity gradient in the SMC. In fact, on analyzing the MD of each field, we derived mean values of [Fe/H] = -0.99 ± 0.08 and [Fe/H] = -1.02 ± 0.07 for fields located closer and farther than 4° from the center of the galaxy, respectively. In addition, there is a clear tendency for the field stars to be more metal-poor than the corresponding cluster they surround, independent of their positions in the galaxy and of the clusters' age. We argue that this most likely stems from the field stars being somewhat older and therefore somewhat more metal-poor than most of our clusters. © 2010. The American Astronomical Society.Fil: Parisi, Maria Celeste. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Geisler, Doug. Universidad de Concepción; ChileFil: Grocholski, A. J.. University of Florida; Estados Unidos. Space Telescope Science Institute; Estados UnidosFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Sarajedini, A.. University of Florida; Estados Unido
Transmitochondrial embryonic stem cells containing pathogenic mtDNA mutations are compromised in neuronal differentiation
Objectives: Defects of the mitochondrial genome (mtDNA) cause a series of rare, mainly neurological disorders. In addition, they have been implicated in more common forms of movement disorders, dementia and the ageing process. In order to try to model neuronal dysfunction associated with mitochondrial disease, we have attempted to establish a series of transmitochondrial mouse embryonic stem cells harbouring pathogenic mtDNA mutations.
Materials and methods: Transmitochondrial embryonic stem cell cybrids were generated by fusion of cytoplasts carrying a variety of mtDNA mutations, into embryonic stem cells that had been pretreated with rhodamine 6G, to prevent transmission of endogenous mtDNA. Cybrids were differentiated into neurons and assessed for efficiency of differentiation and electrophysiological function.
Results: Neuronal differentiation could occur, as indicated by expression of neuronal markers. Differentiation was impaired in embryonic stem cells carrying mtDNA mutations that caused severe biochemical deficiency. Electrophysiological tests showed evidence of synaptic activity in differentiated neurons carrying non-pathogenic mtDNA mutations or in those that caused a mild defect of respiratory activity. Again, however, neurons carrying mtDNA mutations that resulted in severe biochemical deficiency had marked reduction in post-synaptic events.
Conclusions: Differentiated neurons carrying severely pathogenic mtDNA defects can provide a useful model for understanding how such mutations can cause neuronal dysfunction
Washington photometry of open cluster giants: two moderately metal-poor anticentre clusters
New photometric data in the Washington system are presented for red giant candidates in Q1 NGC 1817 and 2251, two open clusters located towards the Galactic anticentre direction. In the case of NGC 2251, the Washington data are supplemented with new UBV and David Dunlap Observatory (DDO) photoelectric photometry. Published radial velocities are used to separate field stars from cluster giants. The photometric data yield an effective temperature and metal abundance for each cluster member. Five independent Washington abundance indices
yield mean metallicities of Fe/H] = −0.33 ± 0.08 and 0.25 ± 0.04 for NGC 1817 and 2251, respectively. From combined BV and DDO data, we also derive E(B − V) = 0.21 ± 0.03 and [Fe/H]DDO = −0.14 ± 0.05 for NGC 2251. Both objects are then found to be on the metal-poor side of the distribution of open clusters, their metallicities being compatible with the existence of a radial abundance gradient in the disc. Using the WEBDA Open Cluster data base and the available literature, we re-examined the overall properties of a sample of 30 clusters located towards the Galactic anticentre with the distances, ages and metallicities available. This cluster sample presents no evidence of an abundance gradient perpendicular to the Galactic plane, nor is an age–metallicity relation found. However, a radial abundance gradient of −0.093 dex kpc−1 is derived over a Galactocentric distance of 14 kpc, a gradient which is in keeping with most recent determinations. This value practically does not change when all clusters with basic parameters known up to this date are considered.Fil: Parisi, Maria Celeste. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: GEISLER, Doug. Universidad de Concepción; Chil
Design of an Automatic System for the University of Missouri Research Reactor's (MURR) Small Diameter Pneumatic-Tube (P-Tube) System [abstract]
Abstract only availableThe nuclear research facility at the University of Missouri-Columbia (MURR) has proposed a redesign of the process for irradiating the samples with INAA (Instrumental Neutron Activation Analysis) in order to increase efficiency (sample throughput), to lower the costs of experiments and to minimized dosage radiation exposure for workers. INAA was discovered in 1936 when Hevesy and Levi found that samples containing certain unusual earth elements became highly radioactive after been in contact to a source of neutrons. From this observation, they rapidly acknowledged the potential of employing nuclear neutron bombardment of samples followed by measurement of the induced radioactivity to smooth the progress of both quantitative and qualitative detection of the elements present in the samples. This new design includes a circular sample storage tray, a pneumatic gripper (for both sealing and for sending and returning of the sample from the reactor), a rotary table motor and two slider motors--one for the gripper and one for moving the sample closer to the counter machine. After the new design was conceived, the Research Reactor needed an automatic control system for the motors that were going to move the samples so they could be sent to the reactor and to the radiation detection room. My responsibility was to design the control system for the operation of the motors. The design (programming) software that I chose to use was LABVIEW programmi
EMAILED 7/26/07!
Overall properties of open clusters projected towards the galactic anticenter direction: Washington photometry of NGC 1817 and NGC 2251
Presentamos fotometrıa de Washington de candidatas a gigantes rojas de los cumulos abiertos NGC 1817 y NGC 2251. Estrellas del campo y gigantes del cumulo se separan en base a velocidades radiales publicadas. Determinamos temperaturas efectivas y metalicidades para cada estrella en ambos cumulos. A partir de nuevos datos fotometricos UBV y DDO, determinamos tambien enrojecimiento y metalicidad de NGC 2251. Las abundancias medias resultantes son [Fe/H] = -0.33 ± 0.08 y -0.20 ± 0.05 para NGC 1817 y NGC 2251, respectivamente. Al examinar las propiedades globales de 30 cumulos proyectados hacia el anticentro galactico con distancias, edades y metalicidades conocidas, no encontramos evidencia sobre un gradiente perpendicular al plano ni sobre una relacion entre la edad y la metalicidad, aunque derivamos un gradiente radial de -0.093 kpc −1 dentro de 14 kpc de distancia galactocentrica. Este valor practicamente no cambia cuando se consideran todos los cumulos con parametros conocidos a la fecha.We present Washington photometry for red giant candidates in the open clusters NGC 1817 and NGC 2251. Published radial velocities are used to separate field stars from cluster giants. Effective temperatures and metal abundances are derived for each star. From new UBV and DDO photometric data, we also derive reddening and metal content for NGC 2251. The resulting mean metallicities are [Fe/H] = -0.33 ± 0.08 and -0.20 ± 0.05 for NGC 1817 and NGC 2251, respectively. We reexamine the overall properties of a sample of 30 clusters in the Galactic anticenter direction with distances, ages and metallicities available. This cluster sample presents no evidence of an abundance gradient perpendicular to the Galactic plane, nor is an age-metallicity relation found. However, a radial abundance gradient of -0.093 dex kpc −1 is derived over a Galactocentric distance of 14 kpc. This value practically does not change when all clusters with basic parameters known up to this date are considered.Fil: Parisi, Maria Celeste. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Geisler, Doug. Universidad de Concepción; Chil
Near-infrared photometry of globular clusters towards the Galactic bulge : observations and photometric metallicity indicators
We present wide-field JHKS photometry of 16 Galactic globular clusters located towards the Galactic bulge, calibrated on the Two Micron All-Sky Survey photometric system. Differential reddening corrections and statistical field star decontamination are employed for all of these clusters before fitting fiducial sequences to the cluster red giant branches (RGBs). Observed values and uncertainties are reported for several photometric features, including the magnitude of the RGB bump, tip, the horizontal branch (HB) and the slope of the upper RGB. The latest spectroscopically determined chemical abundances are used to build distance- and reddening-independent relations between observed photometric features and cluster metallicity, optimizing the sample size and metallicity baseline of these relations by supplementing our sample with results from the literature.We find that the magnitude difference between the HB and the RGB bump can be used to predict metallicities, in terms of both iron abundance [Fe/H] and global metallicity [M/H], with a precision of better than 0.1 dex in all three near-IR bandpasses for relatively metal-rich ([M/H] −1) clusters. Meanwhile, both the slope of the upper RGB and the magnitude difference between the RGB tip and bump are useful metallicity indicators over the entire sampled metallicity range (−2 [M/H] 0) with a precision of 0.2 dex or better, despite model predictions that the RGB slope may become unreliable at high (near-solar) metallicities. Our results agree with previous calibrations in light of the relevant uncertainties, and we discuss implications for clusters with controversial metallicities as well as directions for further investigation
The Space Interferometry Mission Astrometric Grid Giant-Star Survey. I. Stellar Parameters and Radial Velocity Variability
We present results from a campaign of multiple epoch echelle spectroscopy of
relatively faint (V = 9.5-13.5 mag) red giants observed as potential
astrometric grid stars for the Space Interferometry Mission (SIM PlanetQuest).
Data are analyzed for 775 stars selected from the Grid Giant Star Survey
spanning a wide range of effective temperatures (Teff), gravities and
metallicities. The spectra are used to determine these stellar parameters and
to monitor radial velocity (RV) variability at the 100 m/s level. The degree of
RV variation measured for 489 stars observed two or more times is explored as a
function of the inferred stellar parameters. The percentage of radial velocity
unstable stars is found to be very high -- about 2/3 of our sample. It is found
that the fraction of RV-stable red giants (at the 100 m/s level) is higher
among stars with Teff \sim 4500 K, corresponding to the calibration-independent
range of infrared colors 0.59 < (J-K_s)_0 < 0.73. A higher percentage of
RV-stable stars is found if the additional constraints of surface gravity and
metallicity ranges 2.3< log g < 3.2 and -0.5 < [Fe/H] < -0.1, respectively, are
applied. Selection of stars based on only photometric values of effective
temperature (4300 K < Teff < 4700 K) is a simple and effective way to increase
the fraction of RV-stable stars. The optimal selection of RV-stable stars,
especially in the case when the Washington photometry is unavailable, can rely
effectively on 2MASS colors constraint 0.59 < (J-K_s)_0 < 0.73. These results
have important ramifications for the use of giant stars as astrometric
references for the SIM PlanetQuest.Comment: Astronomical Journal, in press, 22 pages, 11 Postscript figures, uses
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A Smartphone-Based Tool for Rapid, Portable, and Automated Wide-Field Retinal Imaging.
Purpose:High-quality, wide-field retinal imaging is a valuable method for screening preventable, vision-threatening diseases of the retina. Smartphone-based retinal cameras hold promise for increasing access to retinal imaging, but variable image quality and restricted field of view can limit their utility. We developed and clinically tested a smartphone-based system that addresses these challenges with automation-assisted imaging. Methods:The system was designed to improve smartphone retinal imaging by combining automated fixation guidance, photomontage, and multicolored illumination with optimized optics, user-tested ergonomics, and touch-screen interface. System performance was evaluated from images of ophthalmic patients taken by nonophthalmic personnel. Two masked ophthalmologists evaluated images for abnormalities and disease severity. Results:The system automatically generated 100° retinal photomontages from five overlapping images in under 1 minute at full resolution (52.3 pixels per retinal degree) fully on-phone, revealing numerous retinal abnormalities. Feasibility of the system for diabetic retinopathy (DR) screening using the retinal photomontages was performed in 71 diabetics by masked graders. DR grade matched perfectly with dilated clinical examination in 55.1% of eyes and within 1 severity level for 85.2% of eyes. For referral-warranted DR, average sensitivity was 93.3% and specificity 56.8%. Conclusions:Automation-assisted imaging produced high-quality, wide-field retinal images that demonstrate the potential of smartphone-based retinal cameras to be used for retinal disease screening. Translational Relevance:Enhancement of smartphone-based retinal imaging through automation and software intelligence holds great promise for increasing the accessibility of retinal screening
An outburst and FU Ori-type disk of a former low luminosity protostar
Strong accretion outbursts onto protostars are associated with emission
dominated by a viscously heated disk, which is characterized by high
luminosities. We report the discovery and characterization of a strong mid-IR
(3.4, 4.6 m) outburst in the embedded protostar SSTgbs J21470601+4739394
(hereafter SSTgbsJ214706). SSTgbsJ214706 has steadily brightened in the
mid-infrared by magnitudes over the past decade, as observed by
NEOWISE. Follow-up investigations with the Gemini near-IR spectrograph reveal
that SSTgbsJ214706 is a binary system with a spatially extended outflow. The
outburst is occurring on the more embedded southeast (SE) component, which
dominates the mid- and far-infrared emission from the source. The outbursting
component exhibits a spectrum consistent with an FU Ori-type outburst,
including the presence of enhanced absorption observed in the molecular bands
of CO. The luminosity of the SE component is estimated to be
L before the outburst and L during the outburst,
which is 1 to 2 orders of magnitude fainter than bonafide FU Ori outbursts. We
interpret this eruption as an FU Ori-type outburst, although the possibility of
brightening following an extinction episode cannot be ruled out. We discuss the
implications and potential explanations for such a low-luminosity eruption
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