Modeling of ion permeation in calcium and sodium channel selectivity filters

Structure-function studies have shown that it is possible to convert a sodium channel to a calcium-selective channel by a single amino acid substitution in the selectivity filter locus. Ion permeation through the "model selectivity filter" was modeled with a reduced set of functional groups representative of the constituent amino acid side chains. Force-field minimizations were conducted to obtain the energy profile of the cations as they get desolvated and bind to the "model selectivity filter." The calculations suggest that the ion selectivity in the calcium channel is due to preferential binding, whereas in the sodium channel it is due to exclusion. Energetics of displacement of a bound cation from the calcium "model selectivity filter" by another cation suggest that "multi-ion mechanism" reduces the activation barrier for ion permeation. Thus, the simple model captures qualitatively most of the conduction characteristics of sodium and calcium channels. However, the computed barriers for permeation are fairly large, suggesting that ion interaction with additional residues along the transport path may be essential to effect desolvation

To freeze or not to: Quantum correlations under local decoherence

We provide necessary and sufficient conditions for freezing of quantum correlations as measured by quantum discord and quantum work deficit in the case of bipartite as well as multipartite states subjected to local noisy channels. We recognize that inhomogeneity of the magnetizations of the shared quantum states plays an important role in the freezing phenomena. We show that the frozen value of the quantum correlation and the time interval for freezing follow a complementarity relation. For states which do not exhibit "exact" freezing, but can be frozen "effectively", by having a very slow decay rate with suitable tuning of the state parameters, we introduce an index -- the freezing index -- to quantify the goodness of freezing. We find that the freezing index can be used to detect quantum phase transitions and discuss the corresponding scaling behavior.Comment: 14 pages, 9 figures, close to published version, title changed by Phys. Rev. A. to 'Freezing of quantum correlations under local decoherence

Onset of deformation at N=112N = 112 in Bi nuclei

The high spin states in $^{195}$Bi has been studied by $\gamma$-ray spectroscopic method using the $^{181}$Ta($^{20}$Ne, 6n) fusion evaporation reaction at 130 MeV. The $\gamma\gamma$ coincidence data were taken using an array of 8 clover HPGe detectors. The spin and parity assignments of the excited states have been made from the measured directional correlation from oriented states (DCO) ratios and integrated polarization asymmetry (IPDCO) ratios. The results show, for the first time, the evidence of a rotational like band based on a 13/2$^+$ band head in this nucleus, indicating the onset of deformation at neutron number $N = 112$ for the Bismuth isotopes. The results obtained were found to be consistent with the prediction of the total Routhian surface calculations using Woods Saxon potential. The same calculations also predict a change in shape from oblate to triaxial in $^{195}$Bi at high rotational frequency

Influence of anti-epileptic drugs on hematological and biochemical parameters in patients with epilepsy

Background: Epilepsy is a chronic neurological condition which may require long-term treatment with antiepileptic drugs (AEDs). The challenge in AED management is to attain freedom from seizures, without side-effects and with good quality-of-life. However, AEDs are reported to induce potential adverse effects, which can remain unnoticed over long time. In this regard, earlier studies report inconsistent results in hematological and biochemical toxicity of AEDs. The objective of the present study was to evaluate the effects of AED monotherapy and polytherapy on hematological and biochemical parameters.Methods: This was a cross-sectional, observational study carried out among patients with epilepsy (PWE) receiving AEDs. The data on baseline demographic characteristics, treatment, adverse drug reactions, hematological, and biochemical investigations were collected. Statistical analysis was performed using the SPSS version 18 and descriptive statistics such as mean and median were used to summarize the data and inferential tests like Chi-square was used to compare categorical variables between groups.Results: There were 255 PWE in mean age range of 28.68±9.29 years, with 56.54% males. A total of 78.04% had focal, 18.04% had generalized seizures and remaining 3.92% were unclassified. Majority of (55.69%) PWE received polytherapy with AEDs. Females had significantly lower levels of hemoglobin (Hb) when compared with males (p=0.000), and patients on AED polytherapy showed significant difference in low Hb (p=0.006) and high alkaline phosphatase (ALP) levels (p=0.001).Conclusions: The results of this study showed significant alterations in the levels of Hb and ALP with the use of AED polytherapy in PWE. Routine hematological and biochemical investigations may be considered during AED treatment in those patients receiving AED polytherapy

Reducing Computational Complexity of Quantum Correlations

We address the issue of reducing the resource required to compute information-theoretic quantum correlation measures like quantum discord and quantum work deficit in two qubits and higher dimensional systems. We show that determination of the quantum correlation measure is possible even if we utilize a restricted set of local measurements. We find that the determination allows us to obtain a closed form of quantum discord and quantum work deficit for several classes of states, with a low error. We show that the computational error caused by the constraint over the complete set of local measurements reduces fast with an increase in the size of the restricted set, implying usefulness of constrained optimization, especially with the increase of dimensions. We perform quantitative analysis to investigate how the error scales with the system size, taking into account a set of plausible constructions of the constrained set. Carrying out a comparative study, we show that the resource required to optimize quantum work deficit is usually higher than that required for quantum discord. We also demonstrate that minimization of quantum discord and quantum work deficit is easier in the case of two-qubit mixed states of fixed ranks and with positive partial transpose in comparison to the corresponding states having non-positive partial transpose. Applying the methodology to quantum spin models, we show that the constrained optimization can be used with advantage in analyzing such systems in quantum information-theoretic language. For bound entangled states, we show that the error is significantly low when the measurements correspond to the spin observables along the three Cartesian coordinates, and thereby we obtain expressions of quantum discord and quantum work deficit for these bound entangled states.Comment: 19 pages, 14 figures, 3 table

Microbial transformation of xenobiotics for environmental bioremediation

The accumulation of recalcitrant xenobiotic compounds is due to continuous efflux from population and industrial inputs that have created a serious impact on the pristine nature of our environment. Apart from this, these compounds are mostly carcinogenic, posing health hazards which persist over a long period of time. Metabolic pathways and specific operon systems have been found in diverse but limited groups of microbes that are responsible for the transformation of xenobiotic compounds.Distinct catabolic genes are either present on mobile genetic elements, such as transposons and plasmids, or the chromosome itself that facilitates horizontal gene transfer and enhances the rapid microbial transformation of toxic xenobiotic compounds. Biotransformation of xenobiotic compounds in natural environment has been studied to understand the microbial ecology, physiology and evolution for their potential in bioremediation. Recent advance in the molecular techniques including DNA fingerprinting, microarrays and metagenomics is being used to augment the transformation of xenobiotic compounds. The present day understandings of aerobic, anaerobic and reductive biotransformation by co-metabolic processes and an overview of latest developments in monitoring the catabolic genes of xenobiotic-degrading bacteria are discussed elaborately in this work. Till date, several reviews have come up, highlighting the problem of xenobiotic pollution, yet a comprehensiveunderstanding of the microbial biodegradation of xenobiotics and its application is in nascent stage. Therefore, this is an attempt to understand the microbial role in biotransformation of xenobiotic compounds in context to the modern day biotechnology

Static and dynamical quantum correlations in phases of an alternating field XY model

We investigate the static and dynamical patterns of entanglement in an anisotropic XY model with an alternating transverse magnetic field, which is equivalent to a two-component one-dimensional Fermi gas on a lattice, a system realizable with current technology. Apart from the antiferromagnetic and paramagnetic phases, the model possesses a dimer phase which is not present in the transverse XY model. At zero temperature, we find that the first derivative of bipartite entanglement can detect all the three phases. We analytically show that the model has a "factorization line" on the plane of system parameters, in which the zero temperature state is separable. Along with investigating the effect of temperature on entanglement in a phase plane, we also report a non-monotonic behavior of entanglement with respect to temperature in the anti-ferromagnetic and paramagnetic phases, which is surprisingly absent in the dimer phase. Since the time dynamics of entanglement in a realizable physical system plays an important role in quantum information processing tasks, the evolutions of entanglement at small as well as large time are examined. Consideration of large time behavior of entanglement helps us to prove that in this model, entanglement is always ergodic. We observe that other quantum correlation measures can qualitatively show similar features in zero and finite temperatures. However, unlike nearest-neighbor entanglement, the nearest-neighbor information theoretic measures can be both ergodic as well as non-ergodic, depending on the system parameters.Comment: 20 Pages, 13 Figures, 2 Tables, Published versio