2,527 research outputs found

    Effects of temperature and ground-state coherence decay on enhancement and amplification in a Δ\Delta atomic system

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    We study phase-sensitive amplification of electromagnetically induced transparency in a warm 85{}^{85}Rb vapor wherein a microwave driving field couples the two lower-energy states of a {\Lambda} energy-level system thereby transforming into a {\Delta} system. Our theoretical description includes effects of ground-state coherence decay and temperature effects. In particular, we demonstrate that driving-field-enhanced electromagnetically induced transparency is robust against significant loss of coherence between ground states. We also show that for specific field intensities, a threshold rate of ground-state coherence decay exists at every temperature. This threshold separates the probe-transmittance behavior into two regimes: probe amplification vs probe attenuation. Thus, electromagnetically induced transparency plus amplification is possible at any temperature in a {\Delta} system

    The effect of substituted benzene dicarboxylic acid linkers on the optical band gap energy and magnetic coupling in manganese trimer metal organic frameworks

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    We have systematically studied a series of eight metal-organic frameworks (MOFs) in which the secondary building unit is a manganese trimer cluster, and the linkers are differently substituted benzene dicarboxylic acids (BDC). The optical band gap energy of the compounds vary from 2.62 eV to 3.57 eV, and theoretical studies find that different functional groups result in new states in the conduction band, which lie in the gap and lower the optical band gap energy. The optical absorption between the filled Mn 3d states and the ligands is weak due to minimal overlap of the states, and the measured optical band gap energy is due to transitions on the BDC linker. The Mn atoms in the MOFs have local moments of 5 mu B, and selected MOFs are found to be antiferromagnetic, with weak coupling between the cluster units, and paramagnetic above 10 K

    Complete genome sequence of BK polyomavirus subtype Ib-1 detected in a kidney transplant patient with BK viremia using shotgun sequencing

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    We report here the complete genome sequence of polyomavirus BK subtype Ib-1, isolate AR11, identified in urine from a human kidney transplant recipient with a clinical diagnosis of BK viremia. The AR11 isolate is closely related to reference strain human polyomavirus 1 isolate J2B-2 with 99% identity

    Toward a Network Model of MHC Class II-Restricted Antigen Processing.

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    The standard model of Major Histocompatibility Complex class II (MHCII)-restricted antigen processing depicts a straightforward, linear pathway: internalized antigens are converted into peptides that load in a chaperone dependent manner onto nascent MHCII in the late endosome, the complexes subsequently trafficking to the cell surface for recognition by CD4(+) T cells (TCD4+). Several variations on this theme, both moderate and radical, have come to light but these alternatives have remained peripheral, the conventional pathway generally presumed to be the primary driver of TCD4+ responses. Here we continue to press for the conceptual repositioning of these alternatives toward the center while proposing that MHCII processing be thought of less in terms of discrete pathways and more in terms of a network whose major and minor conduits are variable depending upon many factors, including the epitope, the nature of the antigen, the source of the antigen, and the identity of the antigen-presenting cell

    Effectiveness of Schema-Based Instruction for Improving Seventh-Grade Students’ Proportional Reasoning: A Randomized Experiment

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    This study examined the effect of schema-based instruction (SBI) on seventh-grade students’ mathematical problem solving performance. SBI is an instructional intervention that emphasizes the role of mathematical structure in word problems and also provides students with a heuristic to self-monitor and aid problem solving. Using a pretest-intervention-posttest-retention test design, the study compared the learning outcomes for 1,163 students in 42 classrooms who were randomly assigned to treatment (SBI) or control condition. After 6 weeks of instruction, results of multilevel modeling indicated significant differences favoring the SBI condition in proportion problem solving involving ratios/rates and percents on an immediate posttest (g = 1.24) and on a six-week retention test (g = 1.27). No significant difference between conditions was found for a test of transfer. These results demonstrate that SBI was more effective than students’ regular mathematics instruction

    Biological Control of F. Oxysporum F. Sp. Lycopersici Causing Wilt of Tomato by Pseudomonas Fluorescens

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    Abstract- Pseudomonas fluorescens is one of the major fungal biocontrol agents found in the soil and the rhizosphere of various crop systems. Ten isolates of P.fluorescens were isolated from rhizosphere soil samples collected from various tomato-growing fields and evaluated for their efficacy in increasing seed quality variables of tomato and in inhibiting the mycelial growth of Fusarium oxysporum. Pseudomonas isolate 2 produced effective results and was selected and mass multiplied. Talc and sodium alginate formulations of mass multiplied using different agents were prepared and evaluated for their effects against fusarium wilt under greenhouse conditions. Fresh cultures of Pf2 isolate was found to increase seedling emergence and reduce fusarium wilt disease incidence when compared to the control and the formulations

    Selection of effective bio-​antagonistic bacteria for biological control of tomato wilt caused by Fusarium oxysporum F. sp. lycopersici

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    Bacteria from the rhizoplane soil and surrounding soil of healthy and Fusarium oxysporum diseased tomato plants of district regions of Karnataka were collected. The best bacterial strains, based on their ability to control development of Fusarium oxysporum isolate, were identified as BS1, BS5 and BS18. All bacterial isolates resulted effective for the in vitro control of growth of Fusarium oxysporum, where the control mechanisms used by the bacteria do not involve the secretion of fungal cell wall hydrolytic enzymes. On the other hand, all bacteria grew well in conditions similar to those that can be found at the field level (considering pH, salinity, Fe3+ and temp.) and showed a good capacity of tomato root colonization. These results suggest that Pseudomonas fluorescens isolates studied have an excellent potential to be used as biocontrol agents of Fusarium oxysporum in tomato greenhouses at the field level

    Sea cucumber conservation in Palk Bay and Gulf of Mannar, India "An evaluation of the current conservation measures on sea cucumber stocks in Palk Bay and Gulf of Mannar of India"

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    Sea cucumber fishery and trade were one of the top non-finfish income streams for the coastal people of Palk Bay and Gulf of Mannar in the South East coast of India. As there was no regulation to control the fishery, there was a concern on decline in sea cucumber populations. In order to conserve the over-exploited stocks, the Ministry of Environment, Forestry and Climate Change, Government of India banned the fishery and trade of sea cucumbers by including them under Wild Life Protection Act 1972 since 2001. The enforcement of a blanket ban of sea cucumber fishing over the last 14 years might have helped in reviving their populations; at the same time, the ban would possibly had a social and economic impact on scores of people, who were dependent on the sea cucumber fishery. To understand the situation, the Bay of Bengal Large Marine Ecosystem (BOBLME) project approved a short term project to Central Marine Fisheries Research Institute (India). The project was intended to understand the sea cucumber stocks and implications of the ban on the livelihood of fishers in Palk Bay and Gulf of Mannar. The purpose of the project was also to suggest management options for conservation and sustainable use of sea cucumber resources
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