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The asymptotic giant branch (AGB) stars with the reddest colors have the largest amounts of circumstellar dust. AGB stars vary in their brightness, and studies show that the reddest AGB stars tend to have longer periods than other AGB stars and are more likely to be fundamental mode pulsators than other AGB stars. Such stars are difficult to study, as they are often not detected at optical wavelengths. Therefore, they must be observed at infrared wavelengths. Using the Spitzer Space Telescope, we have observed a sample of very dusty AGB stars in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) over Cycles 9 through 12 during the Warm Spitzer mission. For each cycle’s program, we typically observed a set of AGB stars at both 3.6 and 4.5 μm wavelength approximately monthly for most of a year. We present results from our analysis of the data from these programs.
This article extends the research focusing on the early origins of psychopathology into the prenatal period, by exploring the association between maternal prenatal depression and offspring (fetal and infant) neurobehavior. The sample is recruited from a rural population in South India where women in the third trimester of pregnancy were assessed for depression and the heart rate responses of their fetuses to extrinsically applied vibroacoustic stimuli were studied. At 2 months postbirth, infant temperament and cortisol responsivity to immunization were assessed. The association between maternal prenatal depression and fetal responsivity to vibroacoustic stimulation, and infant responsivity to immunization, was U shaped with higher levels of responsivity noted in the offspring of mothers with very high and very low depression scores, and lower levels noted in the offspring of mothers with moderate depression scores. Maternal prenatal depression was not associated with infant temperament. The findings highlight the importance of environmental influences in the developmental origins of neurobehavior, suggesting that such differences, not evident at baseline, may emerge upon exposure to stressors. The study also emphasizes the need for further investigation in low- and middle-income contexts by providing preliminary evidence of the differing patterns of association observed between high- and low-income populations.
The resonance modes in Mach 0.94 turbulent flow over a cavity having a length-to-depth ratio of five were explored using time-resolved particle image velocimetry (TR-PIV) and time-resolved pressure sensitive paint (TR-PSP). Mode switching was quantified in the velocity field simultaneous with the pressure field. As the mode number increased from one through three, the resonance activity moved from a region downstream within the recirculation region to areas further upstream in the shear layer, an observation consistent with linear stability analysis. The second and third modes contained organized structures associated with shear layer vortices. Coherent structures occurring in the velocity field during modes two and three exhibited a clear modulation in size with streamwise distance. The streamwise periodicity was attributable to the interference of downstream-propagating vortical disturbances with upstream-travelling acoustic waves. The coherent structure oscillations were approximately
out of phase with the modal surface pressure fluctuations, analogous to a standing wave. Modal propagation (or phase) velocities, based on cross-correlations of bandpass-filtered velocity fields were found for each mode. The phase velocities also showed streamwise periodicity and were greatest at regions of maximum constructive interference where coherent structures were the largest. Overall, the phase velocities increased with modal frequency, which coincided with the modal activity residing at higher portions of the cavity where the local mean flow velocity was elevated. Together, the TR-PIV and TR-PSP provide unique details not only on the distribution of modal activity throughout the cavity, but also new understanding of the resonance mechanism as observed in the velocity field.
Onion thrips, Thrips tabaci (Lindeman), is a prominent species infesting onion and tomato in the northern highlands of Tanzania. It causes considerable leaf damage by direct feeding and also transmits the Iris yellow spot virus (IYSV). Hence, one of the objectives of this study was to identify the most resistant onion entries against T. tabaci. One highly resistant (VI038552) and two resistant onion entries (VI038512 and AVON 1067) were identified against T. tabaci. Besides thrips resistance, the bulb size of VI038512 was also equivalent to one of the commercial varieties, Texas. The highly resistant VI038552 recorded the highest yield, followed by the resistant entry, VI038512. However, the yield of AVON 1067 was significantly lower. Elucidation of the biophysical bases of resistance revealed that there was a significant negative correlation between leaf angle as well as leaf toughness and thrips damage. The total epicuticular wax content in the leaves had a weak and non-significant negative relationship with thrips damage. The scanning electron microscopic study confirmed that the wax crystals occurred as filaments, rods, platelets, tubes and complex dendritic structures, and that they were densely arranged in resistant or moderately resistant entries. Studies on the biochemical basis of resistance confirmed that there was a significant negative relationship between total phenol content and thrips damage. Similarly, the relationship between total foliar amino acids or total sugars and thrips damage was inversely correlated and non-significant. Hence, entries VI038552 and VI038512 could be promising candidates for breeding programmes aimed at developing onion varieties that are resistant to thrips and that are high yielding, which will help to enhance the productivity of onions in sub-Saharan Africa.
We analyze the dust emission features seen in Spitzer Space Telescope Infrared Spectrograph (IRS) spectra of red supergiant (RSG) and oxygen-rich asymptotic giant branch (AGB) stars in the Large Magellanic Cloud and Small Magellanic Cloud galaxies and in various Milky Way globular clusters. The spectra come from the Spitzer Legacy program SAGE-Spectroscopy (PI: F. Kemper), the Spitzer program SMC-Spec (PI: G. Sloan), and other archival Spitzer-IRS programs. The broad 10 and 20 micron emission features attributed to amorphous dust of silicate composition seen in the spectra show evidence for systematic differences in the centroid of both emission features between O-rich AGB and RSG populations. Radiative transfer modeling using the GRAMS grid of models of AGB and RSG stars suggests that the centroid differences are due to differences in dust properties. We investigate differences in dust composition, size, shape, etc that might be responsible for these spectral differences. We explore how these differences may arise from the different circumstellar environments around RSG and O-rich AGB stars and assess effects of varying metallicity (LMC versus SMC versus Milky Way globular cluster) and other properties (mass-loss rate, luminosity, etc.) on the dust originating from these stars. BAS acknowledges funding from NASA ADAP grant NNX13AD54G.
Maternal stress during pregnancy has pervasive effects on stress responsivity in children. This study is the first to test the hypothesis that maternal prenatal depression, as observed in South India, may be associated with how foetuses respond to a potentially stressful stimulus. We employed measures of foetal heart rate at baseline, during exposure to a vibroacoustic stimulus, and post-stimulation, to study patterns of response and recovery in 133 third trimester foetuses of depressed and non-depressed mothers. We show that the association between maternal depression and foetal stress responsivity is U-shaped with foetuses of mothers with high and low depression scores demonstrating elevated responses, and poorer recovery, than foetuses of mothers with moderate levels. The right amount of intra-uterine stimulation is important in conditioning foetuses towards optimal regulation of their stress response. Our results imply that, in certain environmental contexts, exposure to moderate amounts of intra-uterine stress may facilitate this process.
The problems of using performance parameters such as voltage, current and temperature measured with electrical sensors in today’s battery management systems (BMS) are well known. These parameters can be weakly informative about cell state, particularly as cells age, and contribute to over-conservative utilization and oversizing of a battery pack. Fiber optic (FO) sensors can offer an interesting alternative to conventional electrical sensors, with several advantages such as high selective sensitivity to various parameters, light weight, robustness to EMI, and multiplexing capabilities. In this study, a particular type of FO sensors, fiber Bragg grating (FBG) sensors were externally attached to lithium ion pouch cells for monitoring additional informative cell parameter such as strain and temperature. Multiple charge and discharge cycle were performed to examine the qualification of these signals for cell state estimation in BMS. In comparison to corresponding measurements using conventional electrical sensors, the FBG signals showed very promising results for utilization in effective BMS.
Cell aging and state-of-health (SOH) estimation is widely acknowledged as a challenge in state-of-the-art battery management systems deployed today. Towards addressing this issue, gas evolution monitoring from side reactions using embedded sensors was investigated as a parameter of interest for SOH. Li-ion battery cells with a Mn-rich chemistry were subjected to overcharge experiments. Two cells were repeatedly overcharged and the evolution of gaseous CO2 was measured using fiber optic colorimetric sensors, which were incorporated and sealed into the side pouch of the battery pouch cells. A ratiometric read-out principle has been employed for the optical measurements. Initial results indicate a non-reversible gas evolution inside the battery cells during overcharge, wherein the onset of gas evolution is delayed in time relative to the overcharge condition. An increase in the sensing signal can be observed over a time span of 40 – 50 minutes during each overcharge cycle. This investigation provides real-time information on the dynamics of gas evolution in Li-ion pouch cells during overcharge experiments and allows for an early detection of potentially hazardous cell states.
A novel and fundamental method was reported to judge states of lithium ion batteries (LIBs) using the capacitance and the voltage of the cells that were estimated from the real-time currents and voltage characteristics of the cells. We measured the differential capacitance, that is, dQ/dV or delta Q/ delta V that is equal to the currents (I) divided by differential voltages (dV/dt) calculated from the current and the voltage characteristics of the cell during the charging/ discharging, where Q is the charge that flows through the cell, V is the voltage of the cell and t is time. It is thought that the capacitance decrease with the degradation of the cell because the effective area of the electrodes is decreasing due to formation of undesirable compounds. The differential capacitance in some specific voltage range for the LIBs was approximately directly proportional to the state of the degradation of the cell. Therefore, it is concluded that the novel method is very useful to judge the state of the LIBs.
During a routine survey, the scalloped hammerhead shark, Sphyrna lewini was caught from Nagapattinam coastal waters, south-east coast of India. It is the second time this species has occurred after a long period along the Indian coast, and this substantiates the possibility of its entry from another place.
Streptococcus agalactiae is a genetically diverse organism; when typed by pulsed-field gel electrophoresis (PFGE), multiple types appear within a single serotype. We tested whether S. agalactiae PFGE types correspond to a specific serotype within individuals, and different individuals from the same geographic area. A total of 872 S. agalactiae isolates from 152 healthy individuals were classified by PFGE and capsular serotype. Serotype V was the most homogeneous (Simpson's diversity index 0·54); and types III, II and Ib were mostly heterogeneous (Simpson's diversity index ⩾0·90). Within an individual, isolates with the same PFGE patterns had identical capsular types, but across individuals the same PFGE types sometimes occurred in different serotypes. Capsular type alone is insufficient to define epidemiological relatedness. Although PFGE types appear to be a valid surrogate for capsular typing of isolates from the same individual, it is not a valid surrogate for serotype in isolates from different individuals.
The polyvinylidenefluoride (PVdF) based novel polymer electrolytes have been
prepared by solution casting technique for solid state rechargeable
magnesium batteries. Tetraglyme and tetrabutyl ammoniumchloride were used
respectively as plasticizer and filler. The Mg(ClO
was used as
conducting source. A.c. impedance spectroscopy results reveal that 5 wt%
TBACl containing electrolyte show the maximum conductivity of 4.32 × 10-4 S/cm at ambient temperature. This electrolyte was
electrochemically stable upto 1.5 V which was observed through linear sweep
voltammetry. X-ray diffractograms studies suggest that the electrolytes are
completely in amorphous phase. The improved entanglement like surface
morphology was well observed for 5 wt% TBACl containing electrolyte by
scanning electron microscope. The activation energy and coherence length
Early results from the SAGE-SMC (Surveying the Agents of Galaxy Evolution in the tidally-disrupted, low-metallicity Small Magellanic Cloud) Spitzer legacy program are presented. These early results concentrate on the SAGE-SMC MIPS observations of the SMC Tail region. This region is the high H i column density portion of the Magellanic Bridge adjacent to the SMC Wing. We detect infrared dust emission and measure the gas-to-dust ratio in the SMC Tail and find it similar to that of the SMC Body. In addition, we find two embedded cluster regions that are resolved into multiple sources at all MIPS wavelengths.
We are performing a uniform and unbiased imaging survey of the Large Magellanic Cloud (LMC), using the IRAC and MIPS instruments on board the Spitzer Space Telescope (Spitzer). Meixner et al. (2006) provides an overview of the project and initial results and their Table 1 (repeated here) outlines the survey's salient characteristics. In this project, we are surveying the agents of a galaxys evolution (SAGE), i.e. the interstellar medium (ISM) and stars, and their interaction on the galaxy wide scale of the LMC. Spitzer IRAC and MIPS images provide key insights into the life cycle of matter in a galaxy because the infrared emission from dust grains is an effective tracer of the ISM, star formation, and stellar mass-loss. Three key science goals determined the coverage and depth of the survey. The detection of diffuse ISM with column densities > 1.2×1021 H cm−2 permits detailed studies of dust processes in the ISM. SAGE's point source sensitivity enables a complete census of newly formed stars with masses >3 M⊙ that will determine the current star formation rate in the LMC. SAGE's detection of evolved stars with mass loss rates > 10−8 M⊙ yr−1 will quantify the rate at which evolved stars inject mass into the ISM of the LMC (Blum et al. 2006). The SAGE data are nonproprietary. The preliminary SAGE catalog of epoch 1 photometry, prepared by the SAGE Team and released to the public on January 3, 2006, contains over 4 million IRAC sources, band merged with 2MASS photometry and over 60,000 MIPS 24 micron sources. Preliminary estimates indicate that foreground Milky Way stars and background galaxies may comprise as much as 18% and 12%, respectively, of these catalogs. To learn more about the SAGE project: http://sage.stsci.edu/.
Single phase multifunctional materials such as Pb(Fe0.5 Nb0.5)O3 (PFN), where ferroelectric and magnetic order coexist, are very promising and have great interest from the academic and technological points of view. PFN ceramics have been prepared from different kinds of FeNbO4 precursors with either monoclinic or orthorhombic structures. Crystallographic, compositional and surface morphological studies and the temperature-frequency response carried out and reported in previous works are summarized. Ferroelectric hysteretic, magnetic and magnetoelectric behaviors were measured. The remanent polarization (Pr) and coercive field (EC) as functions of temperature and external electric fields (Eext) were determined. Measurements of magnetic susceptibility (χm) exhibited antiferromagnetic order and, above the Núel point near 122 °K, Curie–Weis behavior; whereas a weak ferromagnetic observed from electron paramagnetic resonance (EPR) is discussed. However, magnetoelectric effects were not observed. Ferroelectric and magnetic behaviors, as functions of the kind of precursor used in the preparation, are discussed and correlated with the previous dielectric characterization where microstructural and equivalent circuit models were established using the impedance spectroscopy technique.
Preamorphization implant (PAI) prior to dopant implantation, followed by solid phase epitaxial regrowth (SPER) is of great interest due to its ability to form highly-activated ultra-shallow junctions. Coupled with growing interest in the use of silicon-on-insulator (SOI) wafers, modeling and simulating the influence of SOI structure on damage evolution and ultra-shallow junction formation is required. In this work, we use a kinetic Monte Carlo (kMC) simulator to model the different mechanisms involved in the process of ultra-shallow junction formation, including amorphization, recrystallization, defect interaction and evolution, as well as dopant-defect interaction in both bulk silicon and SOI. Simulation results of dopant concentration profiles and dopant activation are in good agreement with experimental data and can provide important insight for optimizing the process in bulk silicon and SOI.
Investigations on microwave magneto-electric (ME) interactions at 1-10 GHz have been carried out on yttrium iron garnet (YIG)-lead zirconate titanate (PZT) and YIG-lead magnesium niobate lead titanate (PMN-PT) bilayers. Ferromagnetic resonance is a powerful tool for such studies. An electric field E applied to the composite produces a mechanical deformation in PZT or PMN-PT, resulting in a shift in the resonance field for YIG. Information on the nature of high frequency ME coupling has been obtained from data on resonance field shift vs E. A cavity resonator or stripline structure was used. The measured ME interactions are in the range 1-5 Oe cm/kV. The coupling strength has been found to be dependent on magnetic field orientation. The strongest interaction is measured in YIG-PZT systems. The design and characterization of ferromagnetic resonance based, electric field tunable ME resonators and filters are discussed.
Division XI was born by merging Commission 44 “Space and High Energy Astrophysics” and Commission 48 “High Energy Astrophysics” by the decision at the IAU General Assembly in The Hague (1994). As the naming of space astronomy is technique oriented, i.e. astronomy from space, it covers quite a wide range of astronomy, almost all branches of astronomy are included by the progress of space observations. Historically, it started from high energy astronomy, UV, X, and gamma rays astronomy, somewhat including cosmic ray physics. However, in these days, space observations have expanded to low energy astronomy, such as optical, infrared, submillimeter and even radio waves(Space VLBI).