Helical ribbons with pitch angles of either 11 degrees or 54 degrees self-assemble in a wide variety of quaternary surfactant-phospholipid/fatty acid-sterol-water systems. By elastically deforming these helices, we examined their response to uniaxial forces. Under sufficient tension, a low pitch helix reversibly separates into a straight domain with a pitch angle of 90 degrees and a helical domain with a pitch angle of 16.5 degrees. Using a newly developed continuum elastic free energy model, we have shown that this phenomenon can be understood as a first order mechanical phase transition.
In spring 2001, symptoms similar to aphid-vectored peanut stunt disease caused by Peanut stunt virus (PSV) were observed on perennial peanut (Arachis glabrata) cv. Floragraze in Jackson and Gulf counties, FL and Lowndes County, GA. Symptoms observed in commercial hay fields and at the North Florida Research and Education Center in Marianna and Quincy included malformed leaves, plant chlorosis, leaf mottling, and stunted plants, which resulted in reduced foliage yield. Leaf symptoms were visible throughout the growing season. Stunting was more common in spring and early summer. No symptoms were seen on rhizomes. Diagnosis of PSV (genus Cucumovirus) from symptomatic leaves and rhizome materials of 12 plants was confirmed by a direct antigen-coated enzyme-linked immunosorbent assay (DAC-ELISA). ELISA tests were repeated three times. Antibodies specific to the Clemson isolate, serotype E, were obtained from Clemson University, Clemson, SC. DAC-ELISA (1) values of 0.1 A405 above the healthy control for perennial peanut were considered positive for foliage and rhizome material tested. ELISA values ranged from 0.4 to 2.1. The mean ELISA value of the positive controls was 2.65. Symptomatic plants were also tested with ELISA using available antibodies from Agdia Inc., Elkart, IN, for Tomato spotted wilt virus, from ATCC for Peanut stripe virus, and from Clemson University (Cowpea isolate) for Cucumber mosaic virus, but all results were negative. To our knowledge, this is the first report of PSV on perennial peanut in Florida and southern Georgia. At this time, it is not known what role perennial peanut may play as a reservoir of the virus in the vicinity of peanut fields. Little is known about the potential for forage production loss and stand longevity. Next season, molecular detection techniques and epidemiological studies on peanut and perennial peanut will be conducted to ascertain the incidence and possible impact of PSV in Georgia and Florida. Reference: (1) A. G. Gillaspie, Jr. et al. Plant Dis. 79:388, 1995.
Experiments were conducted to determine the influence of date of planting and solar radiatiou on yield of sweet sorghum stalks and sugar. Radiation received by the plants during the period between boot and early seed formation accounted for about 75% of the variation in yield. Maximum solar radiation in south Texas occurs during June, July, and August, consequently maximum yields were obtained from April, May, and June plantings.
Telomerase is a ribonucleoprotein enzyme complex that maintains telomeres at the ends of linear eukaryotic chromosomes. Telomerase minimally requires a telomerase reverse transcriptase (TERT) protein that uses a non‐coding telomerase RNA as a template to extend 3ʹ ends of lagging strands. In addition to binding TERT and providing a template, telomerase RNA plays additional roles in binding accessory proteins and contributing to catalysis. Telomerase RNAs are rapidly evolving in length, sequence and structure, making phylogenetic comparisons challenging and limiting our understanding of telomerase structure‐function relationships. Much of our current grasp of telomerase RNA function results from of loss‐of‐function mutations. In order to better understand telomerase RNA function, we devised a novel screening strategy to identify gain‐of‐function alleles in the budding yeast telomerase RNA. Briefly, our screen utilizes a counter‐selectable marker, URA3, in a subtelomeric region that is sensitive to telomere position effect. When telomeres are long, the URA3 gene will be silenced to a greater extent, allowing better growth of yeast on media containing the chemical 5‐fluoroorotic acid (5‐FOA). To identify novel mutations, we used error‐prone PCR to generate a library of random mutations in a miniaturized version of telomerase RNA, Mini‐T(460). A pilot screen of our mutant library has isolated 5 new gain‐of‐function alleles that allow increased growth of yeast in the presence of 5‐FOA. We are currently scaling up our screen to identify additional gain‐of‐function alleles. Simultaneously, we are investigating the mechanism by which these telomerase RNA alleles lead to longer telomeres. We hypothesize that these mutations could act through one or more mechanisms, including increasing RNA abundance, RNA stability, catalysis, repeat‐addition processivity, and/or protein binding. Together, our work will significantly increase understanding of the structure and function of telomerase RNA.
This paper presents new evidence supporting the development of a screening threshold to evaluate the impact aggregations of solar PV facilities in the northeastern United States can have on voltage deviations in the distribution grid (often called flicker). Using measurements from solar irradiance meters and customer-sited monitoring equipment for residential and light commercial solar systems in Central New York along with data from the Measurement and Instrumentation Data Centers at the Oak Ridge National Laboratory, Elizabeth City State University, and Bluefield College, we present multiple lines of support for the adoption of a flicker screening threshold equivalent to a 5% change in voltage resulting from a full-on to full-off transition of a solar facility. This approach is based on both the newer flicker perception limits in IEEE 1453-2015 and the previous limits derived from the flicker curves in IEEE 519-1992 and is consistent with recent draft recommendations from the Electric Power Research Institute (EPRI) for use in New York. Measurements of correlations between fluctuations at different sites along with a model for high densities of solar facilities are applied to allow the impact of multiple systems on a single feeder to be taken into account while maintaining the simplicity of a single screening threshold.
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