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Direct numerical simulations of high-speed mixing layers are used to characterize the effects of compressibility on the basis of local streamline topology and vortical structure. Temporal simulations of the mixing layers are performed using a finite volume gas-kinetic scheme for convective Mach numbers ranging from
. The focus of the study is on the transient development and the main objectives are to (i) investigate and characterize the turbulence suppression mechanism conditioned upon local streamline topology; and (ii) examine changes in the vortex vector field – distribution, magnitude and orientation – as a function of Mach number. We first reaffirm that kinetic energy suppression with increasing Mach number is due to a decrease in pressure–strain redistribution. Then, we examine the suppression mechanism conditioned upon topology and vortex structure. Conditional statistics indicate that (i) at a given Mach number, shear-dominated topologies generally exhibit more effective pressure–strain redistribution than vortical topologies; and (ii) for a given topology, the level of pressure–strain correlation mostly decreases with increasing Mach number. At each topology, with increasing Mach number, there is a corresponding decrease in turbulent shear stress and production leading to reduced kinetic energy. Further, as
increases, the proportion of vortex-dominated regions in the flow increases, leading to further reduction in the turbulent kinetic energy of the flow. Then, the orientation of vortical structures and direction of fluid rotation are examined using the vortex vector approach of Tian et al. (J. Fluid Mech., vol. 849, 2018, pp. 312–339). At higher
, the vortex vectors tend to be more aligned in the streamwise direction in contrast to low
wherein larger angles with streamwise direction are preferred. The connection between vortex orientation and kinetic energy production is also investigated. The findings lead to improved insight into turbulence suppression dynamics in high Mach number turbulent flows.
Vegetable and grain amaranths represent a vital source of micronutrients and protein in Asia and Africa. However, various foliar lepidopteran pests and stem-mining weevils hinder amaranth production. Insect-resistant cultivars can enhance the productivity of this crop. Here, we report on the performances of amaranth varieties screened for their resistance to insect pests under the field conditions at The World Vegetable Center stations in Asia and sub-Saharan Africa. We conducted two preliminary screening trials with a total of 263 entries from around the world in Taiwan and a third preliminary screening trial with 49 African-indigenous entries in Tanzania. Promising entries from these preliminary trials were collectively evaluated in an advanced screening trial in Tanzania, to identify lines resistant to foliar and stem-boring pests in East Africa. Four entries exhibited moderate resistance to foliar pests: TZ51 and TZ53 (Amaranthus cruentus), TZ34 (A. dubius) and TZ39 (Amaranthus sp.). Five entries showed moderate resistance to stem weevils: TZ06 and TZ27 (A. cruentus), TZ52 (A. graecizans), TZ59 (A. palmeri) and TZ07 (Amaranthus sp.). Lepidopteran pests affecting leaves were reared to adulthood and identified as Spoladea recurvalis (Crambidae), Spodoptera exigua (Noctuidae) and Spodoptera littoralis (Noctuidae). Stem weevil larvae were also reared and identified as: Neocleonus sannio Herbst, Gasteroclisus pr. rhomboidalis Boheman, Hypolixus pr. haerens Boheman and Baradine sp. (Curculionidae). These results highlight key amaranth pests in East Africa and identify insect-resistant entries that will be useful in breeding programmes and resistance studies.
High frequency of low birth weight (LBW) is observed in rural compared with urban Indian women. Since maternal BMI is known to be associated with pregnancy outcomes, the present study aimed to investigate factors associated with BMI in early pregnancy of urban and rural South Indian women.
Prospective observational cohort.
A hospital-based study conducted at an urban and a rural health centre in Karnataka State.
Pregnant women (n 843) aged 18–40 years recruited in early pregnancy from whom detailed sociodemographic, environmental, anthropometric and dietary intake information was collected.
A high proportion of low BMI (32 v. 26 %, P<0·000) and anaemia (48 v. 23 %, P<0·000) was observed in the rural v. the urban cohort. Rural women were younger, had lower body weight, tended to be shorter and less educated. They lived in poor housing conditions, had less access to piped water and good sanitation, used unrefined fuel for cooking and had lower standard of living score. The age (β=0·21, 95 % CI 0·14, 0·29), education level of their spouse (β=1·36, 95 % CI 0·71, 2·71) and fat intake (β=1·24, 95 % CI 0·20, 2·28) were positively associated with BMI in urban women.
Our findings indicate that risk factors associated with BMI in early pregnancy are different in rural and urban settings. It is important to study population-specific risk factors in relation to perinatal health.
The high Himalayan mountains in the north of India are important sources for generating and maintaining the climate over the entire northern belt of the Indian subcontinent. They also influence extreme weather events, such as the western disturbances over the region during winter. The work presented here describes some current trends in weather and climate over the western Himalaya and suggests some possible explanations in the context of climate change. The work also shows how the special features of Indian orography in the western Himalaya affect climate change in the long term, changing the pattern of precipitation over the region. Data analysis of different ranges of the western Himalaya shows significant variations in temperature and snowfall trends in the past few decades. Possible explanations for the changing climate over the western Himalaya are proposed, in terms of variations in cloudiness. The possible effects of climate change on the number of snowfall days and the occurrences of western disturbances over the western Himalaya are also analysed.
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.
In the present study, the effect of heat treatment on microstructure and mechanical properties of gas tungsten arc (GTA) welded 15CDV6 high strength low alloy steel is discussed. Experiments were carried out based on Taguchi L9 orthogonal array to weld 15CDV6 plate of thickness 3.7 mm. The input parameters considered in this work were current, voltage, and welding speed. Tensile strength, microhardness, and impact strength were measured as performance characteristics. Post weld heat treatment was carried out on the weldments to study its effect on the properties of weldments and microstructures were characterized using optical microscope and the X-ray diffraction analysis revealed the presence of MO2C and VC precipitates in the weld. Post weld heat treatment of the GTA welded samples and base metal successfully produced properties required for aerospace applications.
Pneumonia due to either Streptococcus pneumoniae (Sp) or Staphylococcus aureus (Sa) accounts for most mortality after influenza and acute respiratory illness (ARI). Because carriage precedes infection, we estimated Sp and Sa carriage to examine the co-colonization dynamics between Sp, Sa and respiratory viruses in the presence of ARI in the oropharynx. We tested oropharyngeal specimens of community subjects (aged ⩾2 years) with ARI for the presence of influenza A and B, 11 other common respiratory viruses, Sp and Sa, using real-time PCR. A total of 338 participants reported 519 ARI episodes of which 119 (35%) carried Sp, 52 (13%) carried Sa and 25 (7%) carried both. Thirty-five subjects tested positive for influenza, of which 14 (40%) carried Sp and six (17%) carried Sa, significantly more than in the influenza-negative group (P = 0·03 and P = 0·04, respectively). In subjects infected by any virus compared to those with no virus, Sp carriage (39·2% vs. 27·9%, P = 0·03) but not Sa carriage (11·6% vs. 14%, P = 0·6) was more frequent. For children, when Sa was present, Sp carriage tended to be less frequent than expected given the presence of viral infection, but not significantly [observed relative risk 1·14, 95% confidence interval (CI) 0·4–3·1; with a relative excess risk due to interaction of –0·11]. Independent of age, Sp carriers were more likely to return that season with subsequent ARI (odds ratio 2·14, 95% CI 1·1–4·3, P = 0·03). Both Sp and Sa carriage rates in the oropharynx increase during influenza infection in children. However, no negative interaction between Sp and Sa was observed. Sp carriers are more likely to suffer subsequent ARI episodes than non-carriers.
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.
The aim of this study was to identify and develop entomopathogenic fungi as biopesticides for management of Maruca vitrata (Fabricius). Fourteen isolates of Metarhizium anisopliae (Metchnikoff) Sorokin and six of Beauveria bassiana (Bals.-Criv.) Vuill. were screened against first instar larvae of M. vitrata. The two most virulent isolates were selected and further tested for production in four liquid media. Different formulations of one isolate were evaluated against different developmental stages. Metarhizium anisopliae ICIPE 18 and ICIPE 69 caused highest larval mortality of 91 and 81%, with lethal time to 50% mortality (LT50) values of 1.8 and 1.7 days and LC50 of 1.07 × 107 and 3.01 × 106conidia/ml, respectively. ICIPE 69 yielded more biomass and propagules in two liquid media than ICIPE 18. All developmental stages and adult moths were susceptible to fungal infection and horizontal transmission caused a significant reduction in fecundity. Isolate ICIPE 69 was identified as the most potent isolate for managing M. vitrata based on demonstrated efficacy against different developmental stages and amenability to production in liquid media and could be utilized as an alternative to pesticides in cowpea IPM.
Earlier, we showed that rearing of newborn rats on a high-carbohydrate (HC) milk formula resulted in the onset of hyperinsulinemia, its persistence in the post-weaning period and adult-onset obesity. DNA methylation of CpG dinucleotides in the proximal promoter region and modifications in the N-terminal tail of histone 3 associated with the neuropeptide Y (Npy) and pro-opiomelanocortin (Pomc) genes were investigated to decipher the molecular mechanisms supporting the development of obesity in HC females. Although there were no differences in the methylation status of CpG dinucleotides in the proximal promoter region of the Pomc gene, altered methylation of specific CpG dinucleotides proximal to the transcription start site was observed for the Npy gene in the hypothalami of 16- and 100-day-old HC rats compared with their methylation status in mother-fed (MF) rats. Investigation of histone tail modifications on hypothalamic chromatin extracts from 16-day-old rats indicated decreased acetylation of lysine 9 in histone 3 (H3K9) for the Pomc gene and increased acetylation for the same residue for the Npy gene, without changes in histone methylation (H3K9) in both genes in HC rats. These findings are consistent with the changes in the levels of Npy and Pomc mRNAs in the hypothalami of HC rats compared with MF animals. Our results suggest that epigenetic modifications could contribute to the altered gene expression of the Npy and Pomc genes in the hypothalami of HC rats and could be a mechanism leading to hyperphagia and the development of obesity in adult female HC rats.
We surveyed acute care facilities in Florida to assess components of and barriers to sustained antimicrobial stewardship programs (ASPs). Most respondents with and without ASPs are doing some stewardship-related activities to improve antimicrobial use. Collaborative efforts between facilities and health departments are important to providing better resources for ASPs.
Hybrid silicon laser is a promising solution to enable high-performance light source on large-scale, silicon-based photonic integrated circuits (PICs). As a compact laser cavity design, hybrid microring lasers are attractive for their intrinsic advantages of small footprint, low power consumption and flexibility in wavelength division multiplexing (WDM), etc. Here we review recent progress in unidirectional microring lasers and device thermal management. Unidirectional emission is achieved by integrating a passive reflector that feeds laser emission back into laser cavity to introduce extra unidirectional gain. Up to 4X of device heating reduction is simulated by adding a metal thermal shunt to the laser to “short” heat to the silicon substrate through buried oxide layer (BOX) in the silicon-on-insulator (SOI) substrate. Obvious device heating reduction is also observed in experiment.
A low thermal budget process for back-end compatible PCMO based RRAM cell is essential for 3D stacked memory. In this paper, we investigate two strategies to engineer low thermal budget processing for bipolar switching - (i) deposition engineering i.e. based on deposition temperature and oxygen partial pressure, (ii) post deposition anneal i.e. based on inert anneal of room temperature deposited PCMO film.. We demonstrate that both deposition and anneal shows a transition temperature above which bipolar switching is realized. Oxygen partial pressure is a key deposition process parameter. As oxygen partial pressure is reduced memory window increases, however beyond an optimal O2 partial pressure, unipolar switching is observed. Inert anneal is more effective in thermal budget reduction as N2/550°C/2min anneal has same memory performance as 650°C/2hour deposition process.
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.