Maximum-likelihood estimation prevents unphysical Mueller matrices

We show that the method of maximum-likelihood estimation, recently introduced in the context of quantum process tomography, can be applied to the determination of Mueller matrices characterizing the polarization properties of classical optical systems. Contrary to linear reconstruction algorithms, the proposed method yields physically acceptable Mueller matrices even in presence of uncontrolled experimental errors. We illustrate the method on the case of an unphysical measured Mueller matrix taken from the literature.Comment: 3 pages, 1 figur

Polarization Elements-A Group Theoretical Study

The Classification of Polarization elements, the polarization affecting optical devices which have a Jones matrix representation, according to the types of eigenvectors they possess, is given a new visit through the Group-theoretical connection of polarization elements. The diattenuators and retarders are recognized as the elements corresponding to boosts and rotations respectively. The structure of homogeneous elements other than diattenuators and retarders are identified by giving the quaternion corresponding to these elements. The set of degenerate polarization elements is identified with the so called `null' elements of the Lorentz Group. Singular polarization elements are examined in their more illustrative Mueller matrix representation and finally the eigenstructure of a special class of singular Mueller matrices is studied.Comment: 7 pages, 2 tables, submitted to `Optics Communications

INFLUENCE OF HYDRATED SODIUM CALCIUM ALUMINOSILICATE AND ACTIVATED CHARCOAL ON THE PHARMACOKINETICS OF SINGLE PULSE DOSING OF ENROFLOXACIN IN BROILER CHICKEN

ABSTRACTObjective: The present study was undertaken to evaluate the interaction kinetics of enrofloxacin, the commonly used antibacterial in poultry withmycotoxin binders namely hydrated sodium calcium aluminosilicate (HSCAS) and activated charcoal (AC), which have become inevitable componentsof poultry feed.Methods: Control group received normal feed free of toxin binder, whereas HSCAS and AC group were supplemented with HSCAS and AC at 0.5% infeed, respectively. Enrofloxacin was administered as single pulse dose (at 10 mg/kg) through drinking water to all the groups. Blood samples werecollected at predetermined time intervals after drug administration, and plasma was separated and analyzed for enrofloxacin concentrations usinghigh-performance liquid chromatography.Results: Significant decrease in area under the plasma concentration-time curve (AUC0-∞)was noticed in AC group when compared to control group(13.90±1.15 vs. 19.67±1.68 mg.h/ml), whereas HSCAS group (16.42±1.24 mg.h/ml) neither differed significantly from AC nor control group. Thevolume of distribution and clearance were significantly high in AC group when compared to control group (8.31±0.89 vs. 6.39±0.13 l/kg; 0.77±0.07 vs.0.53±0.05 l/h/kg). HSCAS group was intermediate and did not differ significantly from the other two groups (8.13±0.45 l/kg; 0.63±0.04 l/h/kg).However, volume of distribution at steady state was significantly high in both AC (10.42±1.09 l/kg) and HSCAS group (9.45±0.48 l/kg) when comparedto control group (7.21±0.20 l/kg). Maximum plasma concentration was significantly low (0.99±0.04, 0.97±0.06, 1.38±0.04 mg/ml) and time to reachmaximum plasma concentration was significantly delayed (7.33±0.42, 6.67±0.67, 4.33±0.67 h) in AC and HSCAS group when compared to controlgroup, respectively. The relative bioavailability was significantly low in both AC and HSCAS group (74.95±10.70, 88.88±15.03%) when comparedto control group. Pharmacokinetic/pharmacodynamic integration revealed that the dose of enrofloxacin (10 mg/kg) was capable of treating onlymoderately sensitive organisms (minimum inhibitory concentration ≤0.125 mg/ml) both in the presence and absence of toxin binder and higherdosage is needed for the less sensitive organism.Conclusion: The study revealed that the administration of enrofloxacin to HSCAS and AC supplemented broilers would lead to decrease in clinicalefficacy and promote the development of antimicrobial resistance. AC was found to interact more with enrofloxacin than HSCAS as observed fromthe PK parameters. Hence, careful adjustment of dosage or withdrawal of the usage of toxin binder containing either HSCAS or AC in feed duringenrofloxacin treatment is recommended.Keywords: Enrofloxacin, Pulse dosing, Hydrated sodium calcium aluminosilicate, Activated charcoal, Interaction kinetics

FORMULATION DEVELOPMENT AND STATISTICAL OPTIMIZATION OF IVABRADINE HYDROCHLORIDE FLOATING PULSATILE PELLETS BY FLUIDIZED BED COATING TECHNIQUE

ABSTRACTObjective: The objective of the current work was to develop Ivabradine hydrochloride (HCl) floating pulsatile pellets containing drug loaded calciumalginate pellets coated with pH-dependent polymer Eudragit S100 oil dispersion.Methods: Fluidized bed coating technique was used to develop pellets. A 2factorial design was employed to study the effect of independent variables(inlet air temperature, spray rate), on dependent variables (% entrapment efficiency, % friability, and average particle size). Optimization was doneby fitting experimental data to the software program (Minitab). Obtained pellets were subjected to different evaluation parameters which are criticalin the development of the dosage form. An in vitro lag phase study was carried out for all batches in simulated gastric fluid (0.1N HCl) for 5 hrs andin vitro drug release study was carried out for optimized batch (B4) of two different sizes (10/12#, 12/16#) in simulated intestinal fluid (pH 7.4phosphate buffer).2 Results: The optimized batch (B4) showed satisfactory % entrapment efficiency of 92.66±1.52; % friability of 0.57±0.03; and average particle sizeof 1424±16 (µm). All batches maintained lag phase for 5 hrs in 0.1N HCl. An optimized batch of two different sizes exhibited a burst release within30 minutes in simulated intestinal fluid with no significant difference in release rate constant (*p>0.05) and followed first order kinetics.Conclusion: Thus, ivabradine HCl floating pulsatile pellets was successfully developed for treating angina pectoris which is an underlying cause ofheart attack by fluidized bed coating technique employing factorial design.Keywords: Ivabradine hydrochloride, Sodium alginate, Eudragit S100, Pellets, Fluidized bed coating, Optimization, Central composite desig

Detection of Bay of Bengal eddies from TOPEX and in situ observations

Oceanic eddies have warm or cold temperatures and high or low sea surface height (SSH) at the center depending upon the direction of rotation. However, since the Bay of Bengal waters are highly stratified, sea surface temperature (SST) gradients may not be detectable even though the subsurface temperature sections and the SSH show prominent eddy signatures. In this investigation, SSH observations from TOPEX altimeter data and the expendable bathy thermograph (XBT) temperature sections along the Madras-Andamans track have been analyzed to study the Bay of Bengal eddies. Several cyclonic and anticyclonic eddies are identified from the TOPEX altimeter observations. These eddies located along the ship\u27s tracks have significant variations in amplitudes and show good qualitative agreement with the subsurface isotherm features (troughs and ridges) of the in situ temperature profiles. However, this agreement does not extend to the surface and hence SST patterns are not good indicators of eddy positions in the Bay of Bengal where the waters are highly stratified. Therefore, a better approach to the study of eddies in regions like the Bay of Bengal is to use SSH observations. Due to the extensive spatial coverage of remote sensing observations, the exact position and shape of the eddies can be characterized from altimeter-derived SSH observations which is not possible using the limited in situ profiles. Interannual variations in both the positions and intensities of eddies are observed during the study period

Antioxidantes naturales de aceites de semillas de Moringa oleifera variedad Jaffna de origen indio en comparación con otros aceites vegetales

The Moringa oleifera crop is grown all over India for its nutritious pods, leaves and seeds. M. oleifera seeds are endowed with a high oil content (~39%) which resembles olive oil because of its high oleic acid content (~65-75%). The objective of the present study was to evaluate the natural antioxidants of crude seed kernel oil from the Jaffna variety of M. oleifera (MSO). Natural antioxidants like tocopherols and phenolics as well as minor compounds such as sterols and carotenoids present in MSO and its radical scavenging activity were measured in comparison to dried coconut kernel (copra) crude oil (CNO), crude sesame oil (SESO), crude niger seed oil (NSO), crude palm oil (CPO), crude rice bran oil (RBO) and commercially refined groundnut oil (GNO). MSO contained 88 ppm of total tocopherols with α- tocopherol (56.2 ppm) being the major tocopherol. MSO also contained 117.9 ppm of total phenolics with gallic acid (48.5 ppm) being the major phenolic. MSO contained fair amounts of sterols (1700.8 ppm) and carotenoids (17.9 ppm). MSO showed an IC50 value of 35.5 mg mL–1. This study indicates that MSO has antioxidant characteristics which are better than CNO and comparable to those of GNO.Las cosechas de Moringa oleifera se cultivan en toda la India por sus nutritivas vainas, sus hojas y sus semillas. Las semillas de M. oleifera están dotadas de un buen contenido de aceite (~39%) y se asemejan al aceite de oliva debido a su alto contenido de ácido oleico (~65-75%). El objetivo del estudio fue evaluar los antioxidantes naturales de aceites crudos de semillas de M. oleifera variedad de Jaffna (MSO). Los antioxidantes naturales como tocoferoles y fenoles así como esteroles, carotenoides presentes en MSO y su actividad de captación de radicales se midió en comparación con los de aceite crudos de coco desecado (copra) (CNO), de sésamo (SESO), de semilla de niger (NSO), de palma (CPO), de salvado de arroz (RBO) y de cacahuete refinado comercial (GNO). MSO contenía 88 ppm de tocoferoles totales, siendo α-tocoferol el mayoritario (56,2 ppm). MSO también contenía 117,9 ppm de fenoles totales siendo el ácido gálico (48,5 ppm) el mayoritario. MSO contenía también cantidades importantes de esteroles (1700,8 ppm) y carotenoides (17,9 ppm). MSO mostró un valor de CI50 de 35,5 mg mL–1. El estudio indica que MSO tiene características antioxidantes mejores que CNO y comparable con las de GNO