AN INVESTIGATION INTO THE ANALYTICAL UTILITY OF CHANGES IN POLARIZATION ACCOMPANYING ANALYTICAL DERIVATIZATION REACTIONS (FLUORESCENCE)

Derivatization reactions between amines, alcohols and carbonyl groups with various reagents were studied. The goal of the work discussed in this dissertation was to generate basic data to know whether and in what context changes in fluorescence polarization are useful for following analytical derivatization reactions. Reactions between primary amines and fluorescein isothiocyanate were initially studied. Changes in polarization were observed upon conjugation for many of the amines primarily due to changes in fluorescence lifetime. This reaction was also studied in varying amounts of glycerol to judge the effect of glycerol on the reaction rate. Optimum percentages of glycerol were determined. Rate data of reactions of fluorescein isothiocyanate with aniline and p-chloroaniline are reported. Reactions between amines and alcohols with dichlorotriazinyl fluorescein were studied next. Minimal changes in polarization were observed upon conjugation because the lifetimes were very similar to that of the reagent. Glycerol was a problem as it reacts rapidly with the reagent. In a set of kinetics experiments with polyethyleneimine, changes in polarization were observed but could not be distinguished from randomness brought about by the experimental conditions. Dansyl chloride was more difficult to work with than either of the fluorescein compounds due to its sensitivity to environment. This was illustrated by dramatic changes in lifetime as the amount of glycerol in the solution was varied for Perrin plots. The final study involved dansyl hydrazine and reactions with carbonyls. Polarizations again changed upon conjugation due to lifetime changes. Spectral shifts were also noted upon conjugation to two carbonyl compounds. Rate data for reactions with anisaldehyde are reported. A different TLC solvent system is suggested for separation of conjugate and free dansyl hydrazine

Investigating the susceptibility to change of coping and resiliency during COVID-19

On 11 March 2020 the World Health Organization (WHO) declared the outbreak of the novel coronavirus SARS-CoV-2 (COVID-19) a global pandemic. As a result, most of public life, including cultural, sporting, religious and political events, came to a standstill. The current study investigates potential changes in individual’s coping and resiliency during this phase of the pandemic. The present study investigated potential changes in individuals’ coping and resilience during the COVID-19 pandemic. Participants (N = 68), aged between 18 and 34 years old, completed an online survey including the Brief-COPE (Coping Orientation to Problems Experienced) and the SPF-24 (Scale of Protective Factors) at two distinct time points: May 2019 (T0) and May 2020 (T1). To investigate changes between T0 and T1, one-way within-subjects analysis of variances (ANOVAs)’s were conducted. For 11 of 14 the subscales for the Brief-COPE, no significant within-subject sum scores changes were revealed. However, for three subscales, that is, Active Coping (p = 0.005), Venting (p = 0.024) and Acceptance (p = 0.028), significant sum scores changes were revealed. For all four subscales for the SPF-24, no significant within-subjects sum score changes were revealed. For the Brief-COPE, the susceptibility to change for only three of the 14 coping strategies to be significantly influenced by COVID-19, reveals a strong trait-like character of one’s coping strategies. For the SPF-24, all four protective factors were not susceptible to significant changes due to individuals’ experiences of COVID-19.</p

Effects of fungicide application timing and cultivar resistance on Fusarium head blight and deoxynivalenol in winter wheat

Fusarium graminearum causes Fusarium head blight (FHB) in wheat. FHB reduces yield and quality and contaminates grain with the mycotoxin deoxynivalenol (DON). Effective management strategies are needed. The objectives of this research were to 1) Determine the effect of fungicide application timing at anthesis (the standard timing) and 6 and 12 days later on FHB and DON in the winter wheat cultivars Overley (susceptible) and Overland (moderately resistant) and 2) Compare the effects of a triazole and a strobilurin fungicide on FHB and DON in Overley and Overland. In 2015 two field trials (irrigated and rain-fed) were conducted in Nebraska, USA. The triazole Prosaro (prothioconazole + tebuconazole) and the strobilurin Headline (pyraclostrobin) were applied with a CO2-powered backpack sprayer at anthesis and 6 and 12 days later. A split plot design in randomized complete blocks with 4 replications was used. Main plots were cultivars and subplots were fungicide treatments. FHB index and DON were significantly (P \u3c 0.05) lower in Overland than in Overley. The window of fungicide application to control FHB and DON was widened from anthesis to 6 days later without loss of efficacy. Headline was less effective than Prosaro in controlling FHB and DON. Moderate resistance combined with a triazole fungicide most effectively reduced FHB and DON. The results indicate a wider fungicide application window and the effectiveness of combining resistance with a triazole fungicide

Anastral spindle assembly and γ-tubulin in Drosophila oocytes

<p>Abstract</p> <p>Background</p> <p>Anastral spindles assemble by a mechanism that involves microtubule nucleation and growth from chromatin. It is still uncertain whether γ-tubulin, a microtubule nucleator essential for mitotic spindle assembly and maintenance, plays a role. Not only is the requirement for γ-tubulin to form anastral <it>Drosophila </it>oocyte meiosis I spindles controversial, but its presence in oocyte meiosis I spindles has not been demonstrated and is uncertain.</p> <p>Results</p> <p>We show, for the first time, using a bright GFP fusion protein and live imaging, that the <it>Drosophila </it>maternally-expressed γTub37C is present at low levels in oocyte meiosis I spindles. Despite this, we find that formation of bipolar meiosis I spindles does not require functional γTub37C, extending previous findings by others. Fluorescence photobleaching assays show rapid recovery of γTub37C in the meiosis I spindle, similar to the cytoplasm, indicating weak binding by γTub37C to spindles, and fits of a new, potentially more accurate model for fluorescence recovery yield kinetic parameters consistent with transient, diffusional binding.</p> <p>Conclusions</p> <p>The FRAP results, together with its mutant effects late in meiosis I, indicate that γTub37C may perform a role subsequent to metaphase I, rather than nucleating microtubules for meiosis I spindle formation. Weak binding to the meiosis I spindle could stabilize pre-existing microtubules or position γ-tubulin for function during meiosis II spindle assembly, which follows rapidly upon oocyte activation and completion of the meiosis I division.</p

Methods for Compression of Feedback in Adaptive Multicarrier 4G Schemes

In this paper, several algorithms for compressing the feedback of channel quality information are presented and analyzed. These algorithms are developed for a proposed adaptive modulation scheme for future multi-carrier 4G mobile systems. These strategies compress the feedback data and, used together with opportunistic scheduling, drastically reduce the feedback data rate. Thus the adaptive modulation schemes become more suitable and efficient to be implemented in future mobile systems, increasing data throughput and overall system performance.This work has been partly funded by the Spanish government with projects MACAWI (TEC 2005-07477-c02-02), MAMBO2 (CCG06-UC3M-TIC-0698), and European COST Action 289 and is a result of work done within this European actio

Commensurate and Incommensurate Vortex States in Superconductors with Periodic Pinning Arrays

As a function of applied field, we find a rich variety of ordered and partially-ordered vortex lattice configurations in systems with square or triangular arrays of pinning sites. We present formulas that predict the matching fields at which commensurate vortex configurations occur and the vortex lattice orientation with respect to the pinning lattice. Our results are in excellent agreement with recent imaging experiments on square pinning arrays [K. Harada et al., Science 274, 1167 (1996)].Comment: 9 pages, 3 figures. Accepted to Physical Review

FGDB: revisiting the genome annotation of the plant pathogen Fusarium graminearum

The MIPS Fusarium graminearum Genome Database (FGDB) was established as a comprehensive genome database on one of the most devastating fungal plant pathogens of wheat, barley and maize. The current version of FGDB v3.1 provides information on the full manually revised gene set based on the Broad Institute assembly FG3 genome sequence. The results of gene prediction tools were integrated with the help of comparative data on related species to result in a set of 13.718 annotated protein coding genes. This rigorous approach involved adding or modifying gene models and represents a coding sequence gold standard for the genus Fusarium. The gene loci improvements results in 2461 genes which either are new or have different structures compared to the Broad Institute assembly 3 gene set. Moreover the database serves as a convenient entry point to explore expression data results and to obtain information on the Affymetrix GeneChip probe sets. The resource is accessible on http://mips.gsf.de/genre/proj/FGDB/

Melting and transverse depinning of driven vortex lattices in the periodic pinning of Josephson junction arrays

We study the non-equilibrium dynamical regimes of a moving vortex lattice in the periodic pinning of a Josephson junction array (JJA) for {\it finite temperatures} in the case of a fractional or submatching field. We obtain a phase diagram for the current driven JJA as a function of the driving current I and temperature T. We find that when the vortex lattice is driven by a current, the depinning transition at $T_p(I)$ and the melting transition at $T_M(I)$ become separated even for a field for which they coincide in equilibrium. We also distinguish between the depinning of the vortex lattice in the direction of the current drive, and the {\it transverse depinning} in the direction perpendicular to the drive. The transverse depinning corresponds to the onset of transverse resistance in a moving vortex lattice at a given temperature $T_{tr}$. For driving currents above the critical current we find that the moving vortex lattice has first a transverse depinning transition at low T, and later a melting transition at a higher temperature, $T_{M}>T_{tr}$.Comment: 17 pages, 19 figure

Spatio-temporal dynamics and plastic flow of vortices in superconductors with periodic arrays of pinning sites

We present simulations of flux-gradient-driven superconducting rigid vortices interacting with square and triangular arrays of columnar pinning sites in an increasing external magnetic field. These simulations allow us to quantitatively relate spatio-temporal microscopic information of the vortex lattice with typically measured macroscopic quantities, such as the magnetization $M(H)$. The flux lattice does not become completely commensurate with the pinning sites throughout the sample at the magnetization matching peaks, but forms a commensurate lattice in a region close to the edge of the sample. Matching fields related to unstable vortex configurations do not produce peaks in $M(H)$. We observe a variety of evolving complex flux profiles, including flat terraces or plateaus separated by winding current-carrying strings and, near the peaks in $M(H)$, plateaus only in certain regions, which move through the sample as the field increases

Critical Currents and Vortex States at Fractional Matching Fields in Superconductors with Periodic Pinning

We study vortex states and dynamics in 2D superconductors with periodic pinning at fractional sub-matching fields using numerical simulations. For square pinning arrays we show that ordered states form at 1/1, 1/2, and 1/4 filling fractions while only partially ordered states form at other filling fractions, such as 1/3 and 1/5, in agreement with recent imaging experiments. For triangular pinning arrays we observe matching effects at filling fractions of 1/1, 6/7, 2/3, 1/3, 1/4, 1/6, and 1/7. For both square and triangular pinning arrays we also find that, for certian sub-matching fillings, vortex configurations depend on pinning strength. For weak pinning, ordering in which a portion of the vortices are positioned between pinning sites can occur. Depinning of the vortices at the matching fields, where the vortices are ordered, is elastic while at the incommensurate fields the motion is plastic. At the incommensurate fields, as the applied driving force is increased, there can be a transition to elastic flow where the vortices move along the pinning sites in 1D channels and a reordering transition to a triangular or distorted triangular lattice. We also discuss the current-voltage curves and how they relate to the vortex ordering at commensurate and incommensurate fields.Comment: 14 figure