44 research outputs found
Mueller matrix polarimetry of plasmon resonant silver nano-rods: biomedical prospects
Fundamental understanding of the light-matter interaction in the context of
nano-particles is immensely bene- fited by the study of geometry dependent
tunable Localized Surface Plasmon Resonance (LSPR) and has been demonstrated to
have potential applications in various areas of science. The polarization
characteristics of LSPR in addition to spectroscopic tuning can be suitably
exploited in such systems as contrast enhancement mech- anisms and control
parameters. Such polarization characteristics like diattenuation and retardance
have been studied here using a novel combination of Muller-matrix polarimetry
with the T-matrix matrix approach for silver nano-rods to show unprecedented
control and sensitivity to local refractive index variations. The study carried
out over various aspect ratios for a constant equal volume sphere radius shows
the presence of longitu- dinal (dipolar and quadrupolar) and transverse
(dipolar) resonances; arising due to differential contribution of
polarizabilities in two directions. The overlap regions of these resonances and
the resonances themselves exhibit enhanced retardance and diattenuation
respectively. The spectral and amplitude tunability of these polarimetric
parameters through the aspect ratios to span from the minimum to maximum ([0,
1] in the case of diattenuation and [0, {\pi}] in the case of retardance)
presents a novel result that could be used to tailor systems for study of
biological media. On the other hand, the high sensitivity of diattenuation dip
(caused by equal contribution of polarizabilities) could be possibly used for
medium characterization and bio-sensing or bio-imaging studies.Comment: 8 pages, 6 figures, Proceedings of the Saratov Fall Meeting, 201
Medication use pattern and quality assessment of psychiatry outpatient department prescriptions of a tertiary care hospital
Background: Psychiatric illness is a major but often underreported health burden. The field of psychopharmacotherapy is continuously evolving therefore needs monitoring to prevent irrationality. In this setting, authors analyzed the prescribing pattern of psychotropic drugs while simultaneously monitoring prescription quality in a tertiary care teaching private hospital.Methods: A 6 month-prospective observational study was conducted in psychiatry out-patient department. Prescription pattern was analyzed using World Health Organization (WHO) drug use indicators. The quality of the prescriptions was assessed as per prescription writing guidelines issued by The Department of Health and Family Welfare, Government of West Bengal.Results: Of the 745 prescriptions analyzed, depression and psychosis constituted the bulk of diagnosed cases irrespective of any gender predominance. The average number of psychotropic drugs per prescription was 2.85±1.48. Antidepressants, sedative-hypnotic and anxiolytics are most commonly prescribed drugs. 37.58% of psychotropic drugs were given as fixed dose combination, most common being risperidone with trihexyphenidyl. Only 2.91% of the drugs were prescribed in generic name whereas 53.99% were enlisted in national essential medicine list 2015. Polypharmacy and therapeutic duplication were noted in 41% and 26.84 % of prescriptions and dose, duration and frequency were not mentioned in 2.68%, 53.02% and 19.00% of the prescription respectively.Conclusions: Use of psychotropic drugs follows closely with different treatment guideline, though routine uses of central anticholinergics with atypical antipsychotics are not recommended. Despite high utilization of NLEM, more generic prescribing, correct prescription dosing schedule, avoidance of polypharmacy and non-Judicious use of multivitamin FDCs may significantly improve treatment outcome
Non-linear electrical conduction and broadband noise in charge-ordered rare earth manganate Nd_0.5Ca_0.5MnO_3
Measurements of the dc transport properties and the low-frequency
conductivity noise in films of charge ordered Nd_0.5Ca_0.5MnO_3 grown on Si
subtrate reveal the existence of a threshold field in the charge ordered regime
beyond which strong non linear conduction sets in along with a large broad band
conductivity noise. Threshold-dependent conduction disappears as T -> T_{CO},
the charge ordering temperature. This observation suggests that the charge
ordered state gets depinned at the onset of the non-linear conduction.Comment: 3 pages of two-column text and 4 eps figure
Controlled transportation of mesoscopic particles by enhanced spin orbit interaction of light in an optical trap
We study the effects of the spin orbit interaction (SOI) of light in an
optical trap and show that the propagation of the tightly focused trapping beam
in a stratified medium can lead to significantly enhanced SOI. For a plane
polarized incident beam the SOI manifests itself by giving rise to a strong
anisotropic linear diattenuation effect which produces polarization-dependent
off-axis high intensity side lobes near the focal plane of the trap. Single
micron-sized asymmetric particles can be trapped in the side lobes, and
transported over circular paths by a rotation of the plane of input
polarization. We demonstrate such controlled motion on single pea-pod shaped
single soft oxometalate (SOM) particles of dimension around m
over lengths up to 15 m . The observed effects are supported by
calculations of the intensity profiles based on a variation of the Debye-Wolf
approach. The enhanced SOI could thus be used as a generic means of
transporting mesoscopic asymmetric particles in an optical trap without the use
of complex optical beams or changing the alignment of the beam into the trap.Comment: 9 pages, 7 figure
Laws of Black Hole Mechanics from Holst Action
The formulation of Weak Isolated Horizons (WIH) based on the Isolated Horizon
formulation of black hole horizons is reconsidered. The first part of the paper
deals with the derivation of laws of mechanics of a WIH. While the zeroth law
follows from the WIH boundary conditions, first law depends on the action
chosen. We construct the covariant phase space for a spacetime having an WIH as
inner boundary for the Holst action. This requires the introduction of new
potential functions so that the symplectic structure is foliation independent.
We show that a precise cancellation among various terms leads to the usual
first law for WIH. Subsequently, we show from the same covariant phase space
that for spherical horizons, the topological theory on the inner boundary is a
U(1) Chern-Simons theory.Comment: References added, Minor Corrections 25 pages 1 fi
Variations in the SDN Loop of Class A Beta-Lactamases: A Study of the Molecular Mechanism of BlaC (Mycobacterium tuberculosis) to Alter the Stability and Catalytic Activity Towards Antibiotic Resistance of MBIs
The emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis calls for an immediate search for novel treatment strategies. Recently, BlaC, the principal beta-lactamase of Mycobacterium tuberculosis, was recognized as a potential therapeutic target. BlaC belongs to Ambler class A, which is generally susceptible to the beta-lactamase inhibitors currently used in clinics: tazobactam, sulbactam, and clavulanate. Alterations at Ser130 in conserved SDN loop confer resistance to mechanism-based inhibitors (MBIs) commonly observed in various clinical isolates. The absence of clinical evidence of S130G conversion in M. tuberculosis draws our attention to build laboratory mutants of S130G and S130A of BlaC. The study involving steady state, inhibition kinetics, and fluorescence microscopy shows the emergence of resistance against MBIs to the mutants expressing S130G and S130A. To understand the molecular reasoning behind the unavailability of such mutation in real life, we have used circular dichroism (CD) spectroscopy, differential scanning calorimetry (DSC), molecular dynamics (MD) simulation, and stability-based enzyme activity to compare the stability and dynamic behaviors of native and S130G/A mutant form of BlaC. A significant decrease in melting temperature (BlaC T M 60°C, S130A T M 50°C, and S130G T M 45°C), kinetic instability at higher temperature, and comparative dynamic instability correlate the fact that resistance to beta-lactam/beta-lactamase inhibitor combinations will likely not arise from the structural alteration of BlaC, therefore establishing confidence that this therapeutic modality can be potentially applied as a part of a successful treatment regimen against M. tuberculosis
Evidence of a compensated semimetal with electronic correlations at the CNP of twisted double bilayer graphene
Recently, magic-angle twisted bilayer graphene (MATBLG) has shown the
emergence of various interaction-driven novel quantum phases at the
commensurate fillings of the moir'e superlattice, while the charge neutrality
point (CNP) remains mostly a vanilla insulator. Here, we show an emerging phase
of nearly compensated semimetallicity at the CNP of twisted double bilayer
graphene (TDBLG), a close cousin of MATBLG, with signatures of electronic
correlation. Using electrical and thermal transport, we find almost two orders
of magnitude enhancement of the thermopower in magnetic fields much smaller
than the extreme quantum limit, accompanied by a large magnetoresistance() at CNP. This provides indisputable experimental evidence that TDBLG
near CNP is a compensated semimetal. Moreover, at low temperatures, we observe
an unusual sublinear temperature dependence of resistance. A recent theory
predicts the formation of an excitonic metal near CNP, where small electron and
hole pockets coexist. We understand the sublinear temperature dependence in
terms of critical fluctuations in this theory