2,934 research outputs found
More pieces of the puzzle: Chemistry and substructures in the Galactic thick disk
We present a study of the chemical abundances of Solar neighbourhood stars
associated to dynamical structures in the Milky Way's (thick) disk. These stars
were identified as overdensity in the eccentricity range 0.3< ecc < 0.5 in the
Copenhagen-Geneva Survey by Helmi et al. (2006). We find that the stars with
these dynamical characteristics do not constitute a homogeneous population. A
relatively sharp transition in dynamical and chemical properties appears to
occur at a metallicity of [Fe/H] ~ -0.4. Stars with [Fe/H] > -0.4 have mostly
lower eccentricities, smaller vertical velocity dispersions, are alpha-enhanced
and define a rather narrow sequence in [alpha/Fe] vs [Fe/H], clearly distinct
from that of the thin disk. Stars with [Fe/H] < -0.4 have a range of
eccentricities, are hotter vertically, and depict a larger spread in
[alpha/Fe]. We have also found tentative evidence of substructure possibly
associated to the disruption of a metal-rich star cluster. The differences
between these populations of stars is also present in e.g. [Zn/Fe], [Ni/Fe] and
[SmII/Fe], suggesting a real physical distinction.Comment: Astrophysical Journal in press. 5 pages, 4 figure
Crop Pests, Control Measures and Potential Impacts in Kihansi Catchment Area
A baseline survey which covered 349 households in Bomang’ombe and Masisiwe (Kilolo district), Kibengu and Mapanda (Mufindi district) and Chita and Chisano (Kilombero district) was conducted to identify major pests, control measures and potential impacts in Kihansi catchment area. Maize was the most predominant crop being cultivated by 55% of the total respondents in all the study districts. Pests and diseases were the major constraints to crop production, whereby cereal stem borers were the most serious pests being reported by 88.2% of respondents. Application of synthetic pesticides was the major pest control measure, being applied by 66% of the respondents. Increase in pest populations, decline of biodiversity and human health effects were reported by 85%, 61% and 38% of the respondents, respectively, as negative impacts associated with pesticides use. Dissemination of Integrated Pest Management (IPM) packages targeting the key crops and public awareness on good agricultural practices is recommended to sustainably manage the pests and enhance crop production, human health and biodiversity in the catchment.Keywords: Pests; Pesticides; Good Agricultural Practices, Integrated Pest Management, Kihansi
Mapping the Galactic Halo. V. Sgr dSph Tidal Debris 60 degrees from the Main Body
As part of the Spaghetti Project Survey (SPS) we have detected a
concentration of giant stars well above expectations for a smooth halo model.
The position (l~350, b~50) and distance (~50 kpc) of this concentration match
those of the Northern over-density detected by SDSS (Yanny et al. 2000, Ivezic
et al. 2000). We find additional evidence for structure at ~80 kpc in the same
direction. We present radial velocities for many of these stars, including the
first published results from the 6.5m Magellan telescope. The radial velocities
for stars in these structures are in excellent agreement with models of the
dynamical evolution of the Sgr dwarf tidal debris, whose center is 60 degrees
away. The metallicity of stars in these streams is lower than that of the main
body of the Sgr dwarf, which may indicate a radial metallicity gradient prior
to disruption.Comment: 10 pages, 3 figures accepted in Astrophysical Journal Letter
Characterization and dynamics of the peculiar stream Jhelum, A tentative role for the Sagittarius dwarf galaxy
Stellar streams are a promising tool to study the Milky Way's dark matter
subhalo population, as interactions with subhalos could produce substructure in
streams. However, other possible causes for substructure first need to be well
understood. Here we studied the kinematics and the unusual morphology of the
stellar stream Jhelum. Using a combination of ground-based photometry and Gaia
EDR3 astrometry, we characterized the morphology of Jhelum. We combined this
new data with radial velocities from the literature to perform orbit
integrations of the stream in static Galactic potentials. We also carried out
N-body simulations in the presence of the Sagittarius dwarf galaxy. The new
data reveal a previously unreported tertiary component in the stream, as well
as several gaps and a kink-like feature in its narrow component. We find that
for a range of realistic Galactic potentials, no single orbit is able to
reproduce Jhelum's radial velocity data entirely. A generic property of the
orbital solutions is that they share a similar orbital plane to Sagittarius and
this leads to repeated encounters with the stream. Using N-body simulations
that include a massive Sagittarius, we explored its effect on Jhelum, and we
show that these encounters can qualitatively reproduce the narrow and broad
components in Jhelum, as well as create a tertiary component in some cases. We
also find evidence that such encounters can result in an apparent increase in
the velocity dispersion of the stream by a factor up to four due to overlapping
narrow and broad components. Our findings suggest that the Jhelum stream is
even more complex than once thought; however, its morphology and kinematics can
tentatively be explained via the interactions with Sagittarius. In this
scenario, the formation of Jhelum's narrow and broad components occurs
naturally, yet some of the smaller gap-like features remain to be explained.Comment: 17 pages, 17 figure
The Arcturus Moving Group: Its Place in the Galaxy
The Arcturus moving group is a well-populated example of phase space
substructure within the thick disk of our Galaxy. Traditionally regarded as the
remains of a dissolved open cluster, it has recently been suggested to be a
remnant of a satellite accreted by our Galaxy. To investigate the origin of the
group we undertook a high-resolution spectroscopic abundance study of Arcturus
group members and candidates. Examining abundance of Fe, Mg, Ca, Ti, Cr, Ni,
Zn, Ce, Nd, Sm and Gd for 134 stars we found that the group is chemically
similar to disk stars and does not exhibit a clear chemical homogeneity.
Furthermore, we confirm the existence of the Arcturus group using the
Nordstroem et al. (2004), Schuster et al. (2006) and RAdial Velocity Experiment
(RAVE) surveys (Steinmetz et al. 2006). The origin of the group still remains
unresolved: the chemical results are consistent with a dynamical origin but do
not entirely rule out a merger one. Certainly, the Arcturus group provides a
challenge to our understanding of the nature and origin of the Galaxy's thick
disk.Comment: 6 pages, 2 figures, to appear in the Proceedings of the IAU Symposium
254: The Galaxy Disk in Cosmological Contex
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Initial Development toward Non-Invasive Drug Monitoring via Untargeted Mass Spectrometric Analysis of Human Skin.
Drug monitoring is crucial for providing accurate and effective care; however, current methods (e.g., blood draws) are inconvenient and unpleasant. We aim to develop a non-invasive method for the detection and monitoring of drugs via human skin. The initial development toward this aim required information about which drugs, taken orally, can be detected via the skin. Untargeted liquid chromatography-mass spectrometry (LC-MS) was used as it was unclear if drugs, known drug metabolites, or other transformation products were detectable. In accomplishing our aim, we analyzed samples obtained by swabbing the skin of 15 kidney transplant recipients in five locations (forehead, nasolabial area, axillary, backhand, and palm), bilaterally, on two different clinical visits. Untargeted LC-MS data were processed using molecular networking via the Global Natural Products Social Molecular Networking platform. Herein, we report the qualitative detection and location of drugs and drug metabolites. For example, escitalopram/citalopram and diphenhydramine, taken orally, were detected in forehead, nasolabial, and hand samples, whereas N-acetyl-sulfamethoxazole, a drug metabolite, was detected in axillary samples. In addition, chemicals associated with environmental exposure were also detected from the skin, which provides insight into the multifaceted chemical influences on our health. The proof-of-concept results presented support the finding that the LC-MS and data analysis methodology is currently capable of the qualitative assessment of the presence of drugs directly via human skin
Management of undernutrition and failure to thrive in children with congenital heart disease in low- and middle-income countries
Poor growth with underweight for age, decreased length/height for age, and underweight-for-height are all relatively common in children with CHD. The underlying causes of this failure to thrive may be multifactorial, including innate growth potential, severity of cardiac disease, increased energy requirements, decreased nutritional intake, malabsorption, and poor utilisation of absorbed nutrition. These factors are particularly common and severe in low- and middle-income countries. Although nutrition should be carefully assessed in all patients, failure of growth is not a contraindication to surgical repair, and patients should receive surgical repair where indicated as soon as possible. Close attention should be paid to nutritional support - primarily enteral feeding, with particular use of breast milk in infancy - in the perioperative period and in the paediatric ICU. This nutritional support requires specific attention and allocation of resources, including appropriately skilled personnel. Thereafter, it is essential to monitor growth and development and to identify causes for failure to catch-up or grow appropriately
Developmental inventories using illiterate parents as informants:Communicative Development Inventory (CDI) adaptation for two Kenyan languages
Communicative Development Inventories (CDIs, parent-completed language development checklists) are a helpful tool to assess language in children who are unused to interaction with unfamiliar adults. Generally, CDIs are completed in written form, but in developing country settings parents may have insufficient literacy to complete them alone. We designed CDIs to assess language development in children aged 0;8 to 2;4 in two languages used in Coastal communities in Kenya. Measures of vocabulary, gestures, and grammatical constructions were developed using both interviews with parents from varying backgrounds, and vocabulary as well as grammatical constructions from recordings of children's spontaneous speech. The CDIs were then administered in interview format to over 300 families. Reliability and validity ranged from acceptable to excellent, supporting the use of CDIs when direct language testing is impractical, even when children have multiple caregivers and where respondents have low literacy levels
Anomalous crustal movements with low seismic efficiency - Campi Flegrei, Italy and some examples in Japan
Campi Flegrei is a unique volcanic region located near Naples, Italy. Anomalous crustal movements at Pozzuoli in Campi Flegrei have been documented since the Roman period. The movements were gradual and have continued to the present, occasionally accompanying swarms of local earthquakes and volcanic eruptions. Generally the movements proceed with low seismicity. After the 1538 eruption of Monte Nuovo, Pozzuoli had subsided monotonously, but it changed to uplift abruptly in 1969. The uplift accelerated in 1983 and 1984 reaching more than 2 m, and thereafter began to subside. Many discussions of this event have been published. In Japan, we have examples of deformations similar to those at Campi Flegrei, mainly in volcanic areas, and rarely in non-volcanic
areas. The former includes Iwojima, Miyakejima and Aira caldera while the latter is represented by Cape Omaezaki. Iwojima is a volcano island, and its secular uplifts since the 18th century are recognized as an unusual event. Miyakejima volcano and Aira caldera exhibited anomalous movements with low seismicity after their eruptions. Cape Omaezaki is not situated in volcanic zone but near a subduction zone, and gradually and continuously subsides as a precursor to a large earthquake. In such cases as Campi Flegrei and the Japanese localities, we would question whether the deformations are accompanied by normal seismicity or low seismicity. To examine quantitatively the relationship between seismicity and related deformation, seismic efficiency is generally useful. The crustal deformations in all the regions cited above are characterized by exceptionally low seismic efficiencies. In the present paper, the deformations at Pozzuoli and Iwojima are mainly described and a comparative discussion among these and other localities in Japan is supplemented. It is concluded that such anomalous phenomena in volcanic areas are attributable to peculiar rheological aspects of the material composing the local upper crust, and the deformation in a non-volcanic area is of tectonic origin
Halo Star Streams in the Solar Neighborhood
We have assembled a sample of halo stars in the solar neighborhood to look
for halo substructure in velocity and angular momentum space. Our sample
includes red giants, RR Lyrae, and red horizontal branch stars within 2.5 kpc
of the Sun with [Fe/H] less than -1.0. It was chosen to include stars with
accurate distances, space velocities, and metallicities as well as
well-quantified errors. We confirm the existence of the streams found by Helmi
and coworkers, which we refer to as the H99 streams. These streams have a
double-peaked velocity distribution in the z direction. We use the results of
modeling of the H99 streams by Helmi and collaborators to test how one might
use v_z velocity information and radial velocity information to detect
kinematic substructure in the halo. We find that detecting the H99 streams with
radial velocities alone would require a large sample. We use the velocity
distribution of the H99 streams to estimate their age. From our model of the
progenitor of the H99 streams, we determine that it was accreted between 6 and
9 Gyr ago. The H99 streams have [alpha/Fe] abundances similar to other halo
stars in the solar neighborhood, suggesting that the gas that formed these
stars were enriched mostly by Type II SNe. We have also discovered in angular
momentum space two other possible substructures, which we refer to as the
retrograde and prograde outliers. The retrograde outliers are likely to be halo
substructure, but the prograde outliers are most likely part of the smooth
halo. The retrograde outliers have significant structure in the v_phi direction
and show a range of [alpha/Fe]. The methods presented in this paper can be used
to exploit the kinematic information present in future large databases like
RAVE, SDSSII/SEGUE, and Gaia.Comment: 46 pages, 13 figures, and 9 tables. Minor changes to text to match
proofed version of the paper. Low resolution figures. High resolution version
at http://www.astro.wisc.edu/~kepley/solar_streams.p
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