The human as a detector of changes in variance and bandwidth

The detection of changes in random process variance and bandwidth was studied. Psychophysical thresholds for these two parameters were determined using an adaptive staircase technique for second order random processes at two nominal periods (1 and 3 seconds) and damping ratios (0.2 and 0.707). Thresholds for bandwidth changes were approximately 9% of nominal except for the (3sec,0.2) process which yielded thresholds of 12%. Variance thresholds averaged 17% of nominal except for the (3sec,0.2) process in which they were 32%. Detection times for suprathreshold changes in the parameters may be roughly described by the changes in RMS velocity of the process. A more complex model is presented which consists of a Kalman filter designed for the nominal process using velocity as the input, and a modified Wald sequential test for changes in the variance of the residual. The model predictions agree moderately well with the experimental data. Models using heuristics, e.g. level crossing counters, were also examined and are found to be descriptive but do not afford the unification of the Kalman filter/sequential test model used for changes in mean

Molecular dynamics study of the point defects in bcc uranium

Thermodynamic properties of bcc uranium with point defects are studied using ab initio molecular dynamics (MD) simulations at 1100 K. The simulations were performed with canonical ensembles of U127M1,U128M1, and U 126 M1□1 for M = □, He, Ne, Ar, Kr, Xe, Sr, Zr, I, Cs, and Pu disposed on a bcc lattice lying within a 4×4×4 cubic supercell. This work provides formation energies of substitutional, self, and solute interstitial atom defects as well as binding energies of M-□ pair defects. This work demonstrates that our computational scheme based on MD simulations gives reliable formation and binding energies of atomic defects in bcc uranium compared to conventional density functional theory calculations. The equilibrium volume, bulk modulus, and thermal expansion coefficient of pure bcc uranium obtained from our MD simulations compare very well with corresponding experimental results. The vacancy formation energy is predicted to be 0.88 eV. The experimental vacancy formation energy remains uncertain. Experimental study of the formation and binding energies of other point defects as well as the bulk modulus and thermal expansion coefficients of uranium with these defects is also not found in the literature. This work shows that point defects tend to decrease the bulk modulus and increase the thermal expansion coefficient of bcc uranium. The solute formation energies of noble gas atoms show a bearing on their size. A large solute (Xe) has a high formation energy, and vice versa. This size effect is not quite evident for the chemically reactive solutes, namely, Sr, Zr, I, Cs, and Pu. Our MD simulations further show that vacancies are the favorable point defects in bcc uranium rather than both vacancies and self interstitials as predicted by earlier calculations. The formation energies of self interstitial atoms are found to be lower than those of solute interstitial atoms, each calculated in six different basic interstitial dumbbell configurations. That is, bcc U accommodates self interstitials more easily than decay or fission gas interstitials (He, Kr, and Xe). Further, He atoms are found to have comparable formation energies in the substitutional and interstitial locations. The fission product atoms Kr and Xe prefer to occupy vacant substitutional lattice sites rather than interstitial sites. Binding energies of divacancy and solute-vacancy pairs (0.31 vs −0.69 eV for the Xe-□ pair, for instance) from our MD simulation show that nucleation and growth of fission gas bubbles are supported by a thermodynamic driving force, whereas vacancies tend to stay apart. This is in agreement with literature reporting that bcc uranium softens and swells mainly by agglomeration of noble gas bubbles

Crop Protection to Outsmart Climate Change for Food Security & Environmental Conservation

Pearl millet is an important source of energy and nutrition for millions of people in the drylands of sub-Saharan Africa and South Asia. Recently, blast, also known as leaf spot, caused by Magnaporthe grisea (Anamorph: Pyricularia grisea) has emerged as a serious threat to pearl millet cultivation causing substantial yield loss. Seeds tend to contain several storage proteins, some have an inhibitory action against plant pathogens. The present study aimed to identify the defense proteins in seed extrudes of ten pearl millet blast differential lines and investigate their protective effect against growth of Pyricularia grisea (Pg 45, Patancheru isolate). The biochemical observations of seed extrudes revealed the presence of plant defense linked hydrolytic enzymes chitinases (12-18 units/ml), β-1,3 glucanases (16-48 units/mg protein) as well as cysteine protease inhibitors (57-123 PI units/mg protein) among the tested lines. The pre-treatment of P. grisea media with respective line seed extrudes resulted in significant reduction (22-40%; p<0.001) of fungal radial growth and fungal dry weight (20-77%; p<0.001). The effective concentration for the 50% fungal growth inhibition (EC50) was identified as 400 and 600 μg/ml for resistant lines IP 21187 and ICMR 06444, respectively. Further, the seed extrudes were able to significantly retard the spore germination (by 18 h) and initial growth (by 48 h) of Pg 45 by 24-83%. These findings suggest that the identified proteins are playing synergistic role in pearl millet defense against blast pathogen, Pg 45 and provide the basis to explore the novel biological control strategies in plant defense

Use of infrared thermography imaging for assessing heat tolerance in high and low iron pearl millet lines

In the arid regions of Asia and Africa, pearl millet serves as a staple source of dietary energy and mineral micronutrients for millions of people. These regions are more vulnerable to increased temperature. The availability of rapid and efficient screening tools based on the relevant non-destructive quantifiable traits would facilitate pearl millet improvement for heat tolerance. The objective of this study was to evaluate pearl millet lines with contrast micronutrients for heat tolerance using infrared thermal imaging, a rapid proxy-canopy (panicle and flag leaf) temperature measurement. Results showed the highly significant genotypic differences between high-Fe and low-Fe genotypes for grain Fe and Zn densities and agronomic traits. Both high-Fe and low-Fe group genotypes differed significantly for panicle temperature depression (PTD) during high- vapor deficit (VPD) at stigma stage (3.0 to 6.73°C). PTD values were positive across all genotypes during stigma stage and were very low or negative during the low-VPD. Cooler canopy temperature (high-PTD) was observed during stigma stage rather than seed-set stage at higher-VPD in both high-Fe and low-Fe genotypes. The cooler temperature achieved by panicle might be helpful in maintaining stigma receptivity for longer periods in the female parents, whereas in male parents it might be helpful in maintaining pollen viability for longer periods. Flag leaf temperature (FTD) was cooler than PTD at both high-VPD and low-VPD as well in both stigma (less by 2.1°C) and grain-filling stage (less by 2.7°C), again signifying that the reproductive parts are more prone to heat stress as compared to vegetative parts. Since, thermal imaging discriminates the heat stress and non-stress canopies, this can serve as a proxy canopy temperature tool for heat stress tolerance screening in pearl millet

Nanotubes and nanowires

Synthesis and characterization of nanotubes and nanowires constitute an important part of nanoscience since these materials are essential building units for several devices. We have prepared aligned carbon nanotube bundles and Y-junction nanotubes by the pyrolysis of appropriate organic precursors. The aligned bundles are useful for field emission display while the Y-junction nanotubes are likely to be useful as nanochips since they exhibit diode properties at the junction. By making use of carbon nanotubes, nanowires of metals, metal oxides and GaN have been obtained. Both the oxide and GaN nanowires are single crystalline. Gold nanowires exhibit plasmon bands varying markedly with the aspect ratio. GaN nanowires show excellent photoluminescence characteristics. It has been possible to synthesise nanotubes and nanowires of metal chalcogenides by employing different strategies

Quality of symptom elicitation in an epidemiological survey on tuberculosis

The quality of symptom elicited by health workers in an epidemiological survey on tuberculosis was assessed by again subjecting a 10% random sample of the persons interviewed, by the supervisory staff, independently. Three thousand four hundred and forty nine persons were thus interviewed twice. The overall estimates for overdiagnosis and under-diagnosis in the elicitation of symptoms by health workers were to the extent of 16% and 8% respectively, with minimal yield of sputum positivity from the discordant groups of persons. The additional load of 16% for sputum examination can thus be considerably reduced if health workers are well trained in symptom-elicitationscreening of the population and their work is monitored through spot supervisory checks

Crystal structure of ethyl (2S,2′ R)-1′-benzyl-3-oxo-3H-dispiro[1-benzothio-phene-2,3′-pyrrolidine-2′,11″-indeno-[1,2-b]quinoxaline]-4′-carboxylate

The authors thank the TBI X-ray facility, CAS in Crystallography and BioPhysics, University of Madras, Chennai, India, for the data collection.Peer reviewedPublisher PD