105 research outputs found
Classification of the quantum deformation of the superalgebra
We present a classification of the possible quantum deformations of the
supergroup and its Lie superalgebra . In each case, the
(super)commutation relations and the Hopf structures are explicitly computed.
For each matrix, one finds two inequivalent coproducts whether one chooses
an unbraided or a braided framework while the corresponding structures are
isomorphic as algebras. In the braided case, one recovers the classical algebra
for suitable limits of the deformation parameters but this is no
longer true in the unbraided case.Comment: 23p LaTeX2e Document - packages amsfonts,subeqn - misprints and
errors corrected, one section adde
Three dimensional quantum algebras: a Cartan-like point of view
A perturbative quantization procedure for Lie bialgebras is introduced and
used to classify all three dimensional complex quantum algebras compatible with
a given coproduct. The role of elements of the quantum universal enveloping
algebra that, analogously to generators in Lie algebras, have a distinguished
type of coproduct is discussed, and the relevance of a symmetrical basis in the
universal enveloping algebra stressed. New quantizations of three dimensional
solvable algebras, relevant for possible physical applications for their
simplicity, are obtained and all already known related results recovered. Our
results give a quantization of all existing three dimensional Lie algebras and
reproduce, in the classical limit, the most relevant sector of the complete
classification for real three dimensional Lie bialgebra structures given by X.
Gomez in J. Math. Phys. Vol. 41. (2000) 4939.Comment: LaTeX, 15 page
Maps between Deformed and Ordinary Gauge Fields
In this paper, we introduce a map between the q-deformed gauge fields defined
on the GL-covariant quantum hyperplane and the ordinary gauge fields.
Perturbative analysis of the q-deformed QED at the classical level is presented
and gauge fixing la BRST is discussed. An other star product
defined on the hybrid % -plane is explicitly constructed .Comment: 10 page
Classification of bicovariant differential calculi on the Jordanian quantum groups GL_{g,h}(2) and SL_{h}(2) and quantum Lie algebras
We classify all 4-dimensional first order bicovariant calculi on the
Jordanian quantum group GL_{h,g}(2) and all 3-dimensional first order
bicovariant calculi on the Jordanian quantum group SL_{h}(2). In both cases we
assume that the bicovariant bimodules are generated as left modules by the
differentials of the quantum group generators. It is found that there are 3
1-parameter families of 4-dimensional bicovariant first order calculi on
GL_{h,g}(2) and that there is a single, unique, 3-dimensional bicovariant
calculus on SL_{h}(2). This 3-dimensional calculus may be obtained through a
classical-like reduction from any one of the three families of 4-dimensional
calculi on GL_{h,g}(2). Details of the higher order calculi and also the
quantum Lie algebras are presented for all calculi. The quantum Lie algebra
obtained from the bicovariant calculus on SL_{h}(2) is shown to be isomorphic
to the quantum Lie algebra we obtain as an ad-submodule within the Jordanian
universal enveloping algebra U_{h}(sl(2)) and also through a consideration of
the decomposition of the tensor product of two copies of the deformed adjoint
module. We also obtain the quantum Killing form for this quantum Lie algebra.Comment: 33 pages, AMSLaTeX, misleading remark remove
Quantum Symmetries and Marginal Deformations
We study the symmetries of the N=1 exactly marginal deformations of N=4 Super
Yang-Mills theory. For generic values of the parameters, these deformations are
known to break the SU(3) part of the R-symmetry group down to a discrete
subgroup. However, a closer look from the perspective of quantum groups reveals
that the Lagrangian is in fact invariant under a certain Hopf algebra which is
a non-standard quantum deformation of the algebra of functions on SU(3). Our
discussion is motivated by the desire to better understand why these theories
have significant differences from N=4 SYM regarding the planar integrability
(or rather lack thereof) of the spin chains encoding their spectrum. However,
our construction works at the level of the classical Lagrangian, without
relying on the language of spin chains. Our approach might eventually provide a
better understanding of the finiteness properties of these theories as well as
help in the construction of their AdS/CFT duals.Comment: 1+40 pages. v2: minor clarifications and references added. v3: Added
an appendix, fixed minor typo
Interaction between O-GlcNAc Modification and Tyrosine Phosphorylation of Prohibitin: Implication for a Novel Binary Switch
Prohibitin (PHB or PHB1) is an evolutionarily conserved, multifunctional protein which is present in various cellular compartments including the plasma membrane. However, mechanisms involved in various functions of PHB are not fully explored yet. Here we report for the first time that PHB interacts with O-linked Ξ²-N-acetylglucosamine transferase (O-GlcNAc transferase, OGT) and is O-GlcNAc modified; and also undergoes tyrosine phosphorylation in response to insulin. Tyrosine 114 (Tyr114) and tyrosine 259 (Tyr259) in PHB are in the close proximity of potential O-GlcNAc sites serine 121 (Ser121) and threonine 258 (Thr258) respectively. Substitution of Tyr114 and Tyr259 residues in PHB with phenylalanine by site-directed mutagenesis results in reduced tyrosine phosphorylation as well as reduced O-GlcNAc modification of PHB. Surprisingly, this also resulted in enhanced tyrosine phosphorylation and activity of OGT. This is attributed to the presence of similar tyrosine motifs in PHB and OGT. Substitution of Ser121 and Thr258 with alanine and isoleucine respectively resulted in attenuation of O-GlcNAc modification and increased tyrosine phosphorylation of PHB suggesting an association between these two dynamic modifications. Sequence analysis of O-GlcNAc modified proteins having known O-GlcNAc modification site(s) or known tyrosine phosphorylation site(s) revealed a strong potential association between these two posttranslational modifications in various proteins. We speculate that O-GlcNAc modification and tyrosine phosphorylation of PHB play an important role in tyrosine kinase signaling pathways including insulin, growth factors and immune receptors signaling. In addition, we propose that O-GlcNAc modification and tyrosine phosphorylation is a novel previously unidentified binary switch which may provide new mechanistic insights into cell signaling pathways and is open for direct experimental examination
Inhibitory Effects of Prior Low-dose X-irradiation on Ischemia-reperfusion Injury in Mouse Paw
We have reported that low-dose, unlike high-dose, irradiation enhanced antioxidation function and reduced oxidative damage. On the other hand, ischemia-reperfusion injury is induced by reactive oxygen species. In this study, we examined the inhibitory effects of prior low-dose X-irradiation on ischemia-reperfusion injury in mouse paw. BALB/c mice were irradiated by sham or 0.5 Gy of X-ray. At 4 hrs after irradiation, the left hind leg was bound 10 times with a rubber ring for 0.5, 1, or 2 hrs and the paw thickness was measured. Results show that the paw swelling thickness by ischemia for 0.5 hr was lower than that for 2 hrs. At 1 hr after reperfusion from ischemia for 1 hr, superoxide dismutase activity in serum was increased in those mice which received 0.5 Gy irradiation and in the case of the ischemia for 0.5 or 1 hr, the paw swelling thicknesses were inhibited by 0.5 Gy irradiation. In addition, interstitial edema in those mice which received 0.5 Gy irradiation was less than that in the mice which underwent by sham irradiation. These findings suggest that the ischemia-reperfusion injury is inhibited by the enhancement of antioxidation function by 0.5 Gy irradiation
Effects of Transcranial Direct Current Stimulation on Episodic Memory Related to Emotional Visual Stimuli
The present study investigated emotional memory following bilateral transcranial electrical stimulation (direct current of 1 mA, for 20 minutes) over fronto-temporal cortical areas of healthy participants during the encoding of images that differed in affective arousal and valence. The main result was a significant interaction between the side of anodal stimulation and image emotional valence. Specifically, right anodal/left cathodal stimulation selectively facilitated the recall of pleasant images with respect to both unpleasant and neutral images whereas left anodal/right cathodal stimulation selectively facilitated the recall of unpleasant images with respect to both pleasant and neutral images. From a theoretical perspective, this double dissociation between the side of anodal stimulation and the advantage in the memory performance for a specific type of stimulus depending on its pleasantness supported the specific-valence hypothesis of emotional processes, which assumes a specialization of the right hemisphere in processing unpleasant stimuli and a specialization of the left hemisphere in processing pleasant stimuli. From a methodological point of view, first we found tDCS effects strictly dependent on the stimulus category, and second a pattern of results in line with an interfering and inhibitory account of anodal stimulation on memory performance. These findings need to be carefully considered in applied contexts, such as the rehabilitation of altered emotional processing or eye-witness memory, and deserve to be further investigated in order to understand their underlying mechanisms of action
CHEMICAL CONTROL OF THE REDBAY AMBROSIA BEETLE, XYLEBORUS GLABRATUS, AND OTHER SCOLYTINAE (COLEOPTERA: CURCULIONIDAE)
A BSTRACT The redbay ambrosia beetle (RAB), Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae), is an adventive pest of Lauraceae in the southeastern U.S. This wood-boring insect vectors a lethal fungus, Raffaelea lauricola T. C. Harr., Fraedrich & Aghayeva , the causal agent of laurel wilt (LW) disease. The vector-pathogen complex is responsible for extensive mortality of native Persea trees in South Carolina, Georgia, and northern Florida, and now poses an imminent threat to the avocado ( Persea americana Mill.) industry in south Florida. While chemical control of the vector is not viewed as the primary solution, control tactics should be made available to Florida avocado growers. Field and laboratory tests were conducted using avocado bolts, potted avocado trees, and field grown swampbay trees ( Persea palustris (Raf.) Sarg.) treated with contact and systemic insecticides. Zeta-cypermethrin + bifenthrin and lambda-cyhalothrin + thiamethoxam provided the most consistent control of Scolytinae as contact insecticides, while methomyl, malathion, bifenthrin, and endosulfan were more variable in effectiveness. Avocado trees treated with fenpropathrin, cryolite Na Al fluoride, and lambda-cyhalothrin+thiametoxam had similar numbers of beetle entrance holes on treated trees as on the untreated control trees. No statistical differences were observed in disease severity on treated versus non-treated avocados or swampbay. Linear regressions between the number of RAB entrance holes per tree ( x) and LW disease severity ( y a ) and between RAB entrance holes per tree ( x) and recovery of R. lauricola ( y b ) were both significant. Key Words: Redbay ambrosia beetle, avocado, Persea , Xyleborus , Xylosandrus , Hypothenemus , chemical control R ESUMEN El cucarroncito de ambrosia del laurel, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae), es una plaga exΓ³tica de la familia Lauraceae que ha invadido el suroriente de los Estados Unidos. Este insecto barrenador es el vector del hongo, Raffaelea lauricola T.C. Harr., Fraedrich & Aghayeva, agente causal de la enfermedad del secamiento del laurel. El complejo vector-patΓ³geno es responsable de una extensa mortalidad de arboles nativos del genero Persea en Carolina del Sur, Georgia y en el norte de Florida y representa una amenaza inminente para la industria del aguacate ( Persea americana Mill.) de Florida. Aunque el control quΓmico no es la ΓΊnica soluciΓ³n a este problema, se estima que este tipo de opciΓ³n de tΓ‘c-ticas se debe ofrecer a los productores de aguacate. Se condujeron experimentos tanto en campo como en laboratorio utilizando troncos de aguacate, arboles de aguacate y arboles del laurel de la ciΓ©naga ( P. palustris (Raf.) Sarg.), los cuales se trataron con insecticidas de contacto y sistΓ©micos. En general, zetaciypermetrina + bifenthrina y lambda-cyalotrina + tiametoxam dieron un control consistente de los Scolytinae como insecticidas de contacto, mientras que metomΓl, malatiΓ³n y bifentrina y endosulfan dieron resultados variables. No hubo diferencias significativas en los orificios de entrada de los cucarroncitos cuando se trataron los arboles de aguacate con fenpropatrina, floruro de cryolita NA Al y lambda-cyalotrina-tiametoxam comparado con los arboles testigo. No se observaron diferencias estadΓsticas en cuanto a la severidad de la enfermedad entre Γ‘rboles tratados y aquellos no tratados. Sin embargo, modelos de regresiΓ³n lineal entre el nΓΊmero de orificios por Γ‘rbol ( x
Conserved Genes Act as Modifiers of Invertebrate SMN Loss of Function Defects
Spinal Muscular Atrophy (SMA) is caused by diminished function of the Survival of Motor Neuron (SMN) protein, but the molecular pathways critical for SMA pathology remain elusive. We have used genetic approaches in invertebrate models to identify conserved SMN loss of function modifier genes. Drosophila melanogaster and Caenorhabditis elegans each have a single gene encoding a protein orthologous to human SMN; diminished function of these invertebrate genes causes lethality and neuromuscular defects. To find genes that modulate SMN function defects across species, two approaches were used. First, a genome-wide RNAi screen for C. elegans SMN modifier genes was undertaken, yielding four genes. Second, we tested the conservation of modifier gene function across species; genes identified in one invertebrate model were tested for function in the other invertebrate model. Drosophila orthologs of two genes, which were identified originally in C. elegans, modified Drosophila SMN loss of function defects. C. elegans orthologs of twelve genes, which were originally identified in a previous Drosophila screen, modified C. elegans SMN loss of function defects. Bioinformatic analysis of the conserved, cross-species, modifier genes suggests that conserved cellular pathways, specifically endocytosis and mRNA regulation, act as critical genetic modifiers of SMN loss of function defects across species
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