Experimental Test of the Inter-Layer Pairing Models for High-Tc Superconductivity Using Grazing Incidence Infrared Reflectometry

From measurements of the far-infrared reflectivity at grazing angles of incidence with p-polarized light we determined the c-axis Josephson plasma frequencies of the single layer high T_c cuprates Tl_2Ba_2CuO_6 and La_{2-x}Sr_xCuO_4. We detected a strong plasma resonance at 50 cm^{-1} for La_{2-x}Sr_xCuO_4 in excellent agreement with previously published results. For Tl_2Ba_2CuO_6 we were able to determine an upper limit of the unscreened c-axis Josephson plasma frequency 100 cm^{-1} or a c-axis penetration depth > 15 \mu m. The small value of $\omega_J$ stands in contrast to recent a prediction based on the inter-layer tunneling mechanism of superconductivity.Comment: 4 pages, Phys. Rev. B, in press, Revtex, 4 postscript figure

Sum rules and electrodynamics of high-Tc cuprates in the pseudogap state

We explore connections between the electronic density of states (DOS) in a conducting system and the frequency dependence of the scattering rate $1/\tau(\omega)$ inferred from infrared spectroscopy. We show that changes in the DOS upon the development of energy gaps can be reliably tracked through the examination of the $1/\tau(\omega)$ spectra using the sum rules discussed in the text. Applying this analysis to the charge dynamics in high-$T_c$ cuprates we found radically different trends in the evolution of the DOS in the pseudogap state and in the superconducting state.Comment: 4 pages, 3 figure

Restriction site polymorphism-based candidate gene mapping for seedling drought tolerance in cowpea [Vigna unguiculata (L.) Walp.]

Quantitative trait loci (QTL) studies provide insight into the complexity of drought tolerance mechanisms. Molecular markers used in these studies also allow for marker-assisted selection (MAS) in breeding programs, enabling transfer of genetic factors between breeding lines without complete knowledge of their exact nature. However, potential for recombination between markers and target genes limit the utility of MAS-based strategies. Candidate gene mapping offers an alternative solution to identify trait determinants underlying QTL of interest. Here, we used restriction site polymorphisms to investigate co-location of candidate genes with QTL for seedling drought stress-induced premature senescence identified previously in cowpea. Genomic DNA isolated from 113 F2:8 RILs of drought-tolerant IT93K503-1 and drought susceptible CB46 genotypes was digested with combinations of EcoR1 and HpaII, Mse1, or Msp1 restriction enzymes and amplified with primers designed from 13 drought-responsive cDNAs. JoinMap 3.0 and MapQTL 4.0 software were used to incorporate polymorphic markers onto the AFLP map and to analyze their association with the drought response QTL. Seven markers co-located with peaks of previously identified QTL. Isolation, sequencing, and blast analysis of these markers confirmed their significant homology with drought or other abiotic stress-induced expressed sequence tags (EST) from cowpea and other plant systems. Further, homology with coding sequences for a multidrug resistance protein 3 and a photosystem I assembly protein ycf3 was revealed in two of these candidates. These results provide a platform for the identification and characterization of genetic trait determinants underlying seedling drought tolerance in cowpea

Should COVID-19 patients \u3e75 years be Ventilated? An Outcome Study

Background: Elderly patients with COVID-19 disease are at increased risk for adverse outcomes. Current data regarding disease characteristics and outcomes in this population are limited. Aim: To delineate the adverse factors associated with outcomes of COVID-19 patients ≥ 75 years of age. Design: Retrospective cohort study. Methods: Patients were classified into mild/moderate, severe/very severe and critical disease (intubated) based on oxygen requirements. The primary outcome was in-hospital mortality. Results: A total of 355 patients aged ≥ 75 years hospitalized with COVID-19 between 19 March and 25 April 2020 were included.Mean age was 84.3 years. One-third of the patients developed critical disease. Mean length of stay was 7.10 days. Vasopressors were required in 27%, with the highest frequency in the critical disease group (74.1%). Overall mortality was 57.2%, with a significant difference between severity groups (mild/moderate disease: 17.4%, severe/very severe disease: 71.3%, critical disease: 94.9%, P \u3c 0.001).Increased age, dementia, and severe/very severe and critical disease groups were in- dependently associated with increased odds for mortality while diarrhea was associated with decreased odds for mortality (OR: 0.12, 95% CI: 0.02–0.60, P \u3c 0.05). None of the cardiovascular comorbidities were significantly associated with mortality. Conclusion: Age and dementia are associated with increased odds for mortality in patients ≥ 75 years of age hospitalized with COVID-19. Those who require intubation have the greatest odds for mortality. Diarrhea as a presenting symptom was associated with lower odds for mortality

Effect of IMF on the E- and F-region drifts over Patiala

142-147Effect of the eastward and northward components of IMF (By and Bz) on the daytime E-region and nighttime F-region drifts at Patiala, which is situated near the Sq focus , has been studied. Drift records pertaining to the year 1987-88 have been used. The E-region drift speed decreases with increase in B in winter while it increases during summer and equinoxes. It is opposite in the F-region. Significant increase of westward drift with Bz is seen in the E- and F-regions where the correlation coefficients are -0.90 and -0.70 respectively. The southward component of the E-region drift decreases significantly with increase in Bz or By. With increase in By the drift speed in the E-region decreases while it increases in the F-region. The westward components of both the E- and F-region drifts show an increase with an increase in By

Echo Sounding of the Lower Atmosphere: Preliminary Studies

131-136An echosonde system at 2.4 kHz has been developed and installed at the Punjabi University, Patiala. Preliminary results along with geomorphological and climatic conditions in the regions around Patiala are presented. The echograms show domination of inversions in winter and fronts in summer

Echo Sounding of the Lower Atmosphere: Preliminary Studies A Study of Thermal Plumes

137-143Thermal convection has been observed to be a daytime atomospheric phenomenon. The thermal plumes have been recorded with an echosonde over Punjabi University, Patiala. These plumes have been observed up to an altitude of one kilometer of the planetary boundary layer. Detailed studies of the growth and dissipation, occurrence, height, diameter and velocity of the plumes and their effecton microwave communication have been made. They have periods ranging from 1 to 20 min and the diameter varies from 0.2 to 2.40 km, while the vertical velocities vary from a fraction of a metre to 2 meters per second. It is recommended that the pollutants should be released into the atmosphere only under the plume conditions so as to minimize the environmental pollution

Temperature Inversions in the Planetary Boundary Layer

23-28Temperature inversions of several types have been observed over Patiala during initial phases of setting up of an acoustic echosonde in Aug 1980. Surface-based inversions and elevated layers have been observed to be predominantly nighttime phenomena. The thickness of the surface-based inversion is found to be around 100 m while the elevated layers have thickness varying from 20 to 180 m with a peak of occurrence between 30 and 60 m. The surface-based layer rises after sunrise. The total structure in the morning is found to be correlated with radiosonde observations. The water vapour in the atmosphere seems to play a role in controlling the thickness and intensity of the surface-based inversions