Agricultural University of Georgia

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Tbilisi, Georgia

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Strasburger H.,Ludwig Maximilians University of Munich | Malania M.,Agricultural University of Georgia
Journal of Vision | Year: 2013

The loss of positional information for whole letters is one of the most important factors contributing to impaired letter and word recognition. Here we study the quantitative characteristics of flanker confusions in a crowding paradigm and test whether transient spatial attention relieves the crowding effect by reducing flanker confusions. We examined the crowding effect at three eccentricities for a range of flanker distances and attentional cue sizes. The effects of flanker distance confirm earlier findings that errors of both content and position are highest with flankers close by. However, the cue has no effect on flanker confusions and affects content information only, by enhancing target contrast sensitivity independent of cue size.Confusions with the inward, but not the outward, flanker increase linearly with eccentricity.Inward-flanker confusions dominate unlike reported asymmetries for masking. Our results are a psychophysical counterpart to separate neural coding of what and where in pattern recognition.The dependencies of cue effect and confusions on flanker distance scale with eccentricity and can be described by a generalized Bouma critical-separation rule. That rule shows a formal analogy to M scaling, from which the critical crowding distances on a cortical map can be derive as a logarithmic function. The perceptual results are visualized in a "doughnut" model. © 2013 ARVO.


Fallahzadeh M.,Islamic Azad University at Jahrom | Japoshvili G.,Agricultural University of Georgia
Journal of the Entomological Research Society | Year: 2013

The present paper gives a corrected list of Iranian encyrtids published with some errors by different authors. We list 132 species belonging to 45 genera.


Kunchulia M.,Agricultural University of Georgia | Pilz K.S.,University of Aberdeen | Herzog M.H.,Ecole Polytechnique Federale de Lausanne
Scientific Reports | Year: 2014

Nicotine is an important stimulant that is involved in modulating many neuronal processes, including those related to vision. Nicotine is also thought to play a key role in schizophrenia: A genetic variation of the cholinergic nicotine receptor gene, alpha-7 subunit (CHRNA7) has been shown to be associated with stronger backward masking deficits in schizophrenic patients. In this study, we tested visual backward masking in healthy smokers and non-smokers to further understand the effects of nicotine on spatiotemporal vision. In the first study, we tested 48 participants, a group of non-smokers (n = 12) and three groups of regular smokers that were either nicotine deprived (n = 12), non-deprived (n = 12) or deprived but were allowed to smoke a cigarette directly before the start of the experiment (n = 12). Performance was similar across groups, except for some small negative effects in nicotine-deprived participants. In the second study, we compared backward masking performance between regular smokers and non-smokers for older (n = 37, 13 smokers) and younger (n = 67, 21 smokers) adults. Older adults performed generally worse than younger adults but there were no significant differences in performance between smokers and non-smokers. Taken together, these findings indicate that nicotine has no long-term negative effects on visual spatiotemporal processing as determined by visual backward masking.


Diaz A.,Polytechnic University of Catalonia | Katsarava R.,Agricultural University of Georgia | Puiggali J.,Polytechnic University of Catalonia
International Journal of Molecular Sciences | Year: 2014

Poly(alkylene dicarboxylate)s constitute a family of biodegradable polymers with increasing interest for both commodity and speciality applications. Most of these polymers can be prepared from biobased diols and dicarboxylic acids such as 1,4-butanediol, succinic acid and carbohydrates. This review provides a current status report concerning synthesis, biodegradation and applications of a series of polymers that cover a wide range of properties, namely, materials from elastomeric to rigid characteristics that are suitable for applications such as hydrogels, soft tissue engineering, drug delivery systems and liquid crystals. Finally, the incorporation of aromatic units and α-amino acids is considered since stiffness of molecular chains and intermolecular interactions can be drastically changed. In fact, poly(ester amide)s derived from naturally occurring amino acids offer great possibilities as biodegradable materials for biomedical applications which are also extensively discussed. © 2014 by the authors; licensee MDPI, Basel, Switzerland.


Vaughn J.N.,Agricultural University of Georgia | Nelson R.L.,Urbana University | Song Q.,U.S. Department of Agriculture | Cregan P.B.,Agricultural University of Georgia | Li Z.,Agricultural University of Georgia
G3 (Bethesda, Md.) | Year: 2014

Soybean oil and meal are major contributors to world-wide food production. Consequently, the genetic basis for soybean seed composition has been intensely studied using family-based mapping. Population-based mapping approaches, in the form of genome-wide association (GWA) scans, have been able to resolve loci controlling moderately complex quantitative traits (QTL) in numerous crop species. Yet, it is still unclear how soybean's unique population history will affect GWA scans. Using one of the populations in this study, we simulated phenotypes resulting from a range of genetic architectures. We found that with a heritability of 0.5, ∼100% and ∼33% of the 4 and 20 simulated QTL can be recovered, respectively, with a false-positive rate of less than ∼6×10(-5) per marker tested. Additionally, we demonstrated that combining information from multi-locus mixed models and compressed linear-mixed models improves QTL identification and interpretation. We applied these insights to exploring seed composition in soybean, refining the linkage group I (chromosome 20) protein QTL and identifying additional oil QTL that may allow some decoupling of highly correlated oil and protein phenotypes. Because the value of protein meal is closely related to its essential amino acid profile, we attempted to identify QTL underlying methionine, threonine, cysteine, and lysine content. Multiple QTL were found that have not been observed in family-based mapping studies, and each trait exhibited associations across multiple populations. Chromosomes 1 and 8 contain strong candidate alleles for essential amino acid increases. Overall, we present these and additional data that will be useful in determining breeding strategies for the continued improvement of soybean's nutrient portfolio. Copyright © 2014 Vaughn et al.


Ratajova A.,Agricultural University of Georgia
Environmental Science and Pollution Research | Year: 2014

Urban sprawl and increasing economical pressure on agricultural production raises new unprecedented environmental questions. The presented study proved that higher level of fertilization of the urban vegetation significantly increases the concentration of male microgametophytes in the air during the flowering season. The levels of fertilization had no significant effect on the pollen grain size, nor on the profile and content of the phenolic compounds, however, the content of tryptophan (protein with a key role in allergies) was significantly influenced. The metabolism of tryptophan and its role in human imunilogy is not yet completely understood, however, it is recommended to avoid unnecessary fertilization in urbanized areas. © 2014 Springer-Verlag Berlin Heidelberg.


Parasitoids of coccoids were surveyed using malaise traps at the Golcuk Natural Park (Isparta Province), Turkey, in 2009 and 2010. More than 40 species of parasitoids were collected, with twelve being new records for Turkey, of which five, Anagyrus descriptus sp. n., A. alienus sp. n., Aschitus golcukus sp. n., Charitopus bulentyasari sp. n., and Ch. ismailkaracai sp. n. (Hymenoptera: Encyrtidae), are described as new species. © Entomológica Fennica.


Betsiashvili M.,Boyce Thompson Institute for Plant Research | Betsiashvili M.,Agricultural University of Georgia | Ahern K.R.,Boyce Thompson Institute for Plant Research | Jander G.,Boyce Thompson Institute for Plant Research
Journal of Experimental Botany | Year: 2015

Plants show considerable within-species variation in their resistance to insect herbivores. In the case of Zea mays (cultivated maize), Rhopalosiphum maidis (corn leaf aphids) produce approximately twenty times more progeny on inbred line B73 than on inbred line Mo17. Genetic mapping of this difference in maize aphid resistance identified quantitative trait loci (QTL) on chromosomes 4 and 6, with the Mo17 allele reducing aphid reproduction in each case. The chromosome 4 QTL mapping interval includes several genes involved in the biosynthesis of DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one), a maize defensive metabolite that also is required for callose accumulation in response to aphid feeding. Consistent with the known association of callose with plant defence against aphids, R. maidis reproduction on B73×Mo17 recombinant inbred lines was negatively correlated with both DIMBOA content and callose formation. Further genetic mapping, as well as experiments with near-isogenic lines, confirmed that the Mo17 allele causes increased DIMBOA accumulation relative to the B73 allele. The chromosome 6 aphid resistance QTL functions independently of DIMBOA accumulation and has an effect that is additive to that of the chromosome 4 QTL. Thus, at least two separate defence mechanisms account for the higher level of R. maidis resistance in Mo17 compared with B73. © 2014 The Author.


Gamkrelidze M.,Agricultural University of Georgia | Dabrowska K.,Polish Academy of Sciences
Archives of Microbiology | Year: 2014

Analysis of molecular events in T4-infected Escherichia coli has revealed some of the most important principles of biology, including relationships between structures of genes and their products, virus-induced acquisition of metabolic function, and morphogenesis of complex structures through sequential gene product interaction rather than sequential gene activation. T4 bacteriophages and related strains were applied in the first formulations of many fundamental biological concepts. These include the unambiguous recognition of nucleic acids as the genetic material, the definition of the gene by fine-structure mutation, recombinational and functional analyses, the demonstration that the genetic code is triplet, the discovery of mRNA, the importance of recombination and DNA replications, light-dependent and light-independent DNA repair mechanisms, restriction and modification of DNA, self-splicing of intron/exon arrangement in prokaryotes, translation bypassing and others. Bacteriophage T4 possesses unique features that make it a good tool for a multicomponent vaccine platform. Hoc/Soc-fused antigens can be assembled on the T4 capsid in vitro and in vivo. T4-based phage display combined with affinity chromatography can be applied as a new method for bacteriophage purification. The T4 phage display system can also be used as an attractive approach for cancer therapy. The data show the efficient display of both single and multiple HIV antigens on the phage T4 capsid and offer insights for designing novel particulate HIV or other vaccines that have not been demonstrated by other vector systems. © 2014 The Author(s).


Dorfman J.H.,Agricultural University of Georgia | Mandich A.M.,Agricultural University of Georgia
Journal of Regional Science | Year: 2015

This paper extends the literature on amenity migration by focusing on healthcare access for later-life migrants. Previous studies have strongly suggested that natural amenities are strong pull factors for later-life migrants, but high natural amenity counties rarely possess the quality healthcare access optimal for elderly migrants. Utilizing a spatial Bayesian estimation strategy, we explicitly consider numerous drivers of later-life migration to examine the extent to which health access is a driver in location decisions. We find healthcare access measures, including hospital expenditures, hospital beds, and number of doctors, are positively associated with later-life migration decisions. © 2015 Wiley Periodicals, Inc.

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