2,915 research outputs found
Synthesis, spectral characterization and some biological studies of transition metal complexes with Schiff base ligand containing N,O and S as donor atoms
Transition metal complexes of Cu(II), Co(II), Ni(II), Zn(II), Cd(II) and Mn(II) have been synthesized with the Schiff base ligand 5-Sub-N-(2-mercaptophenyl)salicylideneimine. Elemental analysis of these complexes suggest that these metal ions forms complexes of type ML(H2O)stoichiometry for Cu(II), Co(II), Ni(II), Zn(II), Cd(II) and Mn(II). The ligand behaves as tridentate and forms coordinate bonds through O, S and N atoms. Magnetic susceptibility, IR, UV – Visible, Mass and ESR spectral studies suggest that Cu(II), Ni(II) complexes posses square planar geometry, whereas Co(II), Zn(II), Cd(II) and Mn(II) complexes posses tetrahedral geometry. The complexes were tested for their antimicrobial activity against the bacterial strains Staphylococcus aureus and Bacillus subtilis.The Schiff base metal complexes evaluated for their antifungal activity against the fungi A. niger and C. oxysporum. The DNA cleavage studies of Schiff base complexes werestudied using Calf – Thymus DNA by agarose gel electrophoresis method
Quantum-limited metrology and Bose-Einstein condensates
We discuss a quantum-metrology protocol designed to estimate a physical
parameter in a Bose-Einstein condensate of N atoms, and we show that the
measurement uncertainty can decrease faster than 1/N. The 1/N scaling is
usually thought to be the best possible in any measurement scheme. From the
perspective of quantum information theory, we outline the main idea that leads
to a measurement uncertainty that scales better than 1/N. We examine in detail
some potential problems and challenges that arise in implementing such a
measurement protocol using a Bose-Einstein condensate. We discuss how some of
these issues can be dealt with by using lower-dimensional condensates trapped
in nonharmonic potentials.Comment: 32 pages, 1 figure, updated reference
MATRICS cognitive consensus battery (MCCB) performance in children, adolescents, and young adults
Background: Neurodevelopmental models of schizophrenia suggest that cognitive deficits may be observed during childhood and adolescence, long before the onset of psychotic symptoms. Elucidating the trajectory of normal cognitive development during childhood and adolescence may therefore provide a basis for identifying specific abnormalities related to the development of schizophrenia. The MATRICS Consensus Cognitive Battery (MCCB), which was designed for use in clinical trials targeting cognitive deficits most common in schizophrenia, may provide a mechanism to understand this trajectory. To date, however, there is no performance data for the MCCB in healthy children and adolescents. The present study sought to establish performance data for the MCCB in healthy children, adolescents, and young adults. Methods: The MCCB was administered to a community sample of 190 healthy subjects between the ages of 8 and 23 years. All MCCB domain scores were converted to T-scores using sample means and standard deviations and were compared for significant performance differences between sex and age strata. Results: Analyses revealed age effects following quadratic trends in all MCCB domains, which is consistent with research showing a leveling off of childhood cognitive improvement upon approaching late adolescence. Sex effects after controlling for age only presented for one MCCB domain, with males exhibiting well-known spatial reasoning advantages. Conclusions: Utilizing this performance data may aid future research seeking to elucidate specific deficits that may be predictive of later development of SZ. (C) 2013 Elsevier B.V. All rights reserved
Maps for Lorentz transformations of spin
Lorentz transformations of spin density matrices for a particle with positive
mass and spin 1/2 are described by maps of the kind used in open quantum
dynamics. They show how the Lorentz transformations of the spin depend on the
momentum. Since the spin and momentum generally are entangled, the maps
generally are not completely positive and act in limited domains. States with
two momentum values are considered, so the maps are for the spin qubit
entangled with the qubit made from the two momentum values, and results from
the open quantum dynamics of two coupled qubits can be applied. Inverse maps
are used to show that every Lorentz transformation completely removes the spin
polarization, and so completely removes the information, from a number of spin
density matrices. The size of the spin polarization that is removed is
calculated for particular cases.Comment: 7 Pages, 3 Figure
Mapping the Schrodinger picture of open quantum dynamics
For systems described by finite matrices, an affine form is developed for the
maps that describe evolution of density matrices for a quantum system that
interacts with another. This is established directly from the Heisenberg
picture. It separates elements that depend only on the dynamics from those that
depend on the state of the two systems. While the equivalent linear map is
generally not completely positive, the homogeneous part of the affine maps is,
and is shown to be composed of multiplication operations that come simply from
the Hamiltonian for the larger system. The inhomogeneous part is shown to be
zero if and only if the map does not increase the trace of the square of any
density matrix. Properties are worked out in detail for two-qubit examples.Comment: 10 pages, 3 Figures, Accepted for publication in Phys. Rev.
Dynamics of stick-slip in peeling of an adhesive tape
We investigate the dynamics of peeling of an adhesive tape subjected to a
constant pull speed. We derive the equations of motion for the angular speed of
the roller tape, the peel angle and the pull force used in earlier
investigations using a Lagrangian. Due to the constraint between the pull
force, peel angle and the peel force, it falls into the category of
differential-algebraic equations requiring an appropriate algorithm for its
numerical solution. Using such a scheme, we show that stick-slip jumps emerge
in a purely dynamical manner. Our detailed numerical study shows that these set
of equations exhibit rich dynamics hitherto not reported. In particular, our
analysis shows that inertia has considerable influence on the nature of the
dynamics. Following studies in the Portevin-Le Chatelier effect, we suggest a
phenomenological peel force function which includes the influence of the pull
speed. This reproduces the decreasing nature of the rupture force with the pull
speed observed in experiments. This rich dynamics is made transparent by using
a set of approximations valid in different regimes of the parameter space. The
approximate solutions capture major features of the exact numerical solutions
and also produce reasonably accurate values for the various quantities of
interest.Comment: 12 pages, 9 figures. Minor modifications as suggested by refere
Evidence of fibrinogen as a target of citrullination in IgM rheumatoid factor-positive polyarticular juvenile idiopathic arthritis
<p>Abstract</p> <p>Background</p> <p>Several studies have noted the significance of measuring anti-cyclic citrullinated peptide (CCP) antibodies in juvenile idiopathic arthritis (JIA) as an important indicator for destructive disease, as is the case in rheumatoid arthritis (RA). While the role of anti-CCP antibodies in RA and JIA has become better understood, the identity of the target proteins of this modification has remained elusive. In this study, we evaluated serum from patients with various subtypes of JIA to investigate the presence of anti-deiminated (citrullinated) fibrinogen and anti-citrullinated α-enolase antibodies, and their association with RF and anti-CCP antibody isotypes.</p> <p>Methods</p> <p>Sera were obtained from 96 JIA patients, 19 systemic lupus erythematosus (SLE) patients, and 10 healthy children. All sera were measured for antibodies against citrullinated and native fibrinogen and α-enolase by an enzyme linked immunosorbent assay (ELISA). In addition, all sera were assayed for anti-CCP antibody isotypes and rheumatoid factor (RF) isotypes by ELISA. The relationship between anti-citrullinated fibrinogen and anti-α-enolase antibodies and disease activity and joint damage were also investigated. All results were correlated with clinical and laboratory parameters using Spearman's rho correlation coefficient. Multiple logistic regression analysis was utilized to identify which variables were associated with joint erosions and diagnosis of JIA.</p> <p>Results</p> <p>Thirty-one JIA patients (32%) demonstrated reactivity to citrullinated fibrinogen and 9 (9%) to citrullinated α-enolase. Reactivity to citrullinated fibrinogen and α-enolase was predominantly found in IgM RF-positive polyarthritis patients. Fourteen JIA patients reacted with native α-enolase and a higher percentage of SLE patients reacted with citrullinated α-enolase when compared to JIA patients. Anti-citrullinated fibrinogen antibodies correlated with the presence of IgG anti-CCP antibodies and IgA and IgM RF. The presence of anti-citrullinated α-enolase antibodies correlated with IgA anti-CCP antibodies. IgG anti-CCP antibodies were significantly associated with joint damage and anti-citrullinated fibrinogen antibodies were strongly associated with JIA when compared to control groups. Anti-citrullinated fibrinogen antibodies demonstrated high sensitivity (81%) for IgM RF-positive polyarticular JIA. IgG anti-CCP antibodies had the highest specificity (95%) for JIA, with anti-citrullinated fibrinogen antibodies, IgA anti-CCP antibodies and IgA RF all following at 84%.</p> <p>Conclusions</p> <p>JIA patient sera exhibited strong reactivity to anti-citrullinated fibrinogen antibodies and demonstrated high sensitivity and specificity for JIA, primarily in IgM RF-positive polyarthritis patients. Fibrinogen is one of several protein targets for citrullination in JIA.</p
Identification of R368H as a predominant CYP1B1 allele causing primary congenital glaucoma in Indian patients
Purpose: To investigate the predominant mutation in the CYP1B1 gene in patients in India with primary congenital glaucoma (PCG), using PCR-restriction fragment length polymorphism (RFLP) methods and to characterize the molecular defect in two generations of an affected family. Methods: DNA samples from 146 patients with PCG from 138 pedigrees were analyzed for several distinct mutations in CYP1B1 by PCR-RFLP. Results: PCR-RFLP screening revealed that 30.8% of patients were positive for any one of the six mutations (376insA, 528G→A, 923C→T, 959G→A, 1449G→A, and 1514C→A), and 17.8% of the patients were found to have the rarely reported mutation R368H (1449G→A). All mutations were confirmed by DNA sequencing. Conclusions: The results suggest extensive allelic heterogeneity in the Indian patients with PCG, with the predominant allele being R368H among the 146 Indian patients tested. It appears possible to use this approach for carrier detection in pedigrees with a positive family history and in population screening. The approach also offers a method for rapid screening of potential carriers and affected individuals
pH dependence of cyanide and imidazole binding to the heme domains of \u3cem\u3eSinorhizobium meliloti\u3c/em\u3e and \u3cem\u3eBradyrhizobium japonicum\u3c/em\u3e FixL
Equilibrium and kinetic properties of cyanide and imidazole binding to the heme domains of Sinorhizobium meliloti and Bradyrhizobium japonicum FixL (SmFixLH and BjFixLH) have been investigated between pH 5 and 11. KD determinations were made at integral pH values, with the strongest binding at pH 9 for both ligands. KD for the cyanide complexes of BjFixLH and SmFixLH is 0.15 ± 0.09 and 0.50 ± 0.20 μM, respectively, and 0.70 ± 0.01 mM for imido-BjFixLH. The association rate constants are pH dependent with maximum values of 443 ± 8 and 252 ± 61 M−1 s−1 for cyano complexes of BjFixLH and SmFixLH and (5.0 ± 0.3) × 104 and (7.0±1.4) × 104M−1 s−1 for the imidazole complexes. The dissociation rate constants are essentially independent of pH above pH 5; (1.2 ± 0.3) × 10−4 and (1.7 ± 0.3) × 10−4 s−1 for the cyano complexes of BjFixLH and SmFixLH, and (73±19) and (77±14) s−1 for the imidazole complexes. Two ionizable groups in FixLH affect the rate of ligand binding. The more acidic group, identified as the heme 6 propionic acid, has a pKa of 7.6 ± 0.2 in BjFixLH and 6.8 ± 0.2 in SmFixLH. The second ionization is due to formation of hydroxy-FixLH with pKa values of 9.64± 0.05 for BjFixLH and 9.61 ± 0.05 for SmFixLH. Imidazole binding is limited by the rate of heme pocket opening with maximum observed values of 680 and 1270 s−1 for BjFixLH and SmFixLH, respectively
Causal connectivity of evolved neural networks during behavior
To show how causal interactions in neural dynamics are modulated by behavior, it is valuable to analyze these interactions without perturbing or lesioning the neural mechanism. This paper proposes a method, based on a graph-theoretic extension of vector autoregressive modeling and 'Granger causality,' for characterizing causal interactions generated within intact neural mechanisms. This method, called 'causal connectivity analysis' is illustrated via model neural networks optimized for controlling target fixation in a simulated head-eye system, in which the structure of the environment can be experimentally varied. Causal connectivity analysis of this model yields novel insights into neural mechanisms underlying sensorimotor coordination. In contrast to networks supporting comparatively simple behavior, networks supporting rich adaptive behavior show a higher density of causal interactions, as well as a stronger causal flow from sensory inputs to motor outputs. They also show different arrangements of 'causal sources' and 'causal sinks': nodes that differentially affect, or are affected by, the remainder of the network. Finally, analysis of causal connectivity can predict the functional consequences of network lesions. These results suggest that causal connectivity analysis may have useful applications in the analysis of neural dynamics
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