Dual-band, double-negative, polarization-independent metamaterial for the visible spectrum

We present the first dual-band negative index metamaterial that operates in the visible spectrum. The optimized four-functional-layer metamaterial structure exhibits the first double-negative (i.e., simultaneously negative permittivity and permeability) band in the red region of the visible spectrum with a figure of merit of 1.7 and the second double-negative band in the green region of the visible spectrum with a figure of merit of 3.2. The optical behavior of the proposed structure is independent of the polarization of the incident field. This low-loss metamaterial structure can be treated as a modified version of a fishnet metamaterial structure with an additional metal layer of different thickness in a single functional layer. The additional metal layer extends the diluted plasma frequency deep into the visible spectrum above the second order magnetic resonance of the structure, hence provides a dual band operation with simultaneously negative effective permittivity and permeability. Broadband metamaterials with multiple negative index bands may be possible with the same technique by employing higher order magnetic resonances. The structure can be fabricated with standard microfabrication techniques that have been used to fabricate fishnet metamaterial structures.Comment: 26 Pages, 6 Figures, 2 Tables, 2 Medi

Car bomb: from Belfast to Baghdad

Belfast on 21st July 1972 will always be remembered as a black day for those covering the history of the troubles in Northern Ireland, for it is the day that the Provisional Irish Republican Army (IRA) set a precedent which even today is the curse of all urban conflict: The deadly car bomb

Surface plasmon driven scalable low-loss negative-index metamaterials at visible spectrum

We demonstrate that surface plasmons of a thin metal film interacting with a periodic array of nano-structures around it can be utilized to make bulk negative index metamaterials at visible spectrum with simultaneously negative permittivity and permeability. These surface plasmon driven metamaterials have high figure of merit and can be tuned arbitrarily to operate at any wavelength in the visible spectrum and possibly at ultraviolet spectrum. We numerically demonstrate the idea by a metamaterial structure which exhibits a strong magnetic response resulting in a negative index of refraction in the green region of the electromagnetic spectrum at 536nm with a figure of merit of 3.67. We also demonstrate by simply changing the constituent material only, hence by modifying the underlying surface plasmon dispersion, that the operating wavelength of the structure can be blue-shifted to the violet region at 406nm with a figure of merit of 2.27. In contrast to the fishnet-structure based approaches for visible metamaterials, our proposed approach offers a more frequency scalable way of achieving negative index of refraction in the visible and possibly at ultraviolet wavelengths with high figure of merit.Comment: Accepted for publication in Physical Review B, 7 journal page, 6 figure

DISPOSITION KINETICS AND DOSAGE REGIMEN OF TAMOXIFEN IN ADULT HEALTHY FEMALE VOLUNTEERS

Breast cancer is the second most pervasive cause of mortalities in the world and Tamoxifen is the hormone therapy of choice in pre-menopausal estrogen receptor positive breast cancer women and sometimes in post-menopausal women. The pharmgeonetics factors widely affect the pharmacokinetic parameters. Information regarding this anti breast cancer drug shows that bio disposition of Tamoxifen has not been widely studied in local healthy adult female subjects. Disposition kinectics and dosage regimen were investigated in eight healthy adult females of a specific age group 35-55 years. Blood samples were collected at various intervals after oral administration 20mg Tamoxifen tablet. Plasma concentrations were determined with HPLC. Plasma concentration versus time curve was analyzed with one compartment pharmacokinetic model to calculate the kinetic parameters such as Cmax and volume of distribution etc. The pharmacokinetic analysis revealed Cmax of 28.11 ± 2.11 ng/mL at mean Tmax of 7.7 hours.The mean ± SE volume of distribution was 306.6 ± 3.681 L/kg ,respectively while extrapolated zero time drug concentration of elimination phase 0.037 ± 0.005ng/mL. Mean ± SE rate constant for elimination phase was 0.12 ± 0.002 hr-1. Due to decrease in Cmax attained after single oral dose, it is recommended that dosing interval of Tamoxifen should be decreased as to attain steady state levels for pharmacotherapeutic results in breast cancer females. However, 5-10ng/mL change is due to the changes of environment, epigenetic and genetic variation between Pakistan and drug manufacturing foreign countries

OSCA: a comprehensive open-access system of analysis of posterior capsular opacification

BACKGROUND: This paper presents and tests a comprehensive computerised system of analysis of digital images of posterior capsule opacification (PCO). It updates and expands significantly on a previous presentation to include facilities for selecting user defined central areas and for registering and subsequent merging of images for artefact removal. Also, the program is compiled and thus eliminates the need for specialised additional software. The system is referred to in this paper as the open-access systematic capsule assessment (OSCA). The system is designed to be evidence based, objective and openly available, improving on current systems of analysis. METHODS: Principal features of the OSCA system of analysis are discussed. Flash artefacts are automatically located in two PCO images and the images merged to produce a composite free from these artefacts. For this to be possible the second image has to be manipulated with a registration technique to bring it into alignment with the first. Further image processing and analysis steps use a location-sensitive entropy based texture analysis of PCO. Validity of measuring PCO progression of the whole new system is assessed along with visual significance of scores. Reliability of the system is assessed. RESULTS: Analysis of PCO by the system shows ability to detect early progression of PCO, as well as detection of more visually significant PCO. Images with no clinical PCO produce very low scores in the analysis. Reliability of the system of analysis is demonstrated. CONCLUSION: This system of PCO analysis is evidence-based, objective and clinically useful. It incorporates flash detection and removal as well as location sensitive texture analysis. It provides features and benefits not previously available to most researchers or clinicians. Substantial evidence is provided for this system's validity and reliability

RENAL CLEARANCE AND URINARY EXCRETION OF CIPROFLOXACIN IN GOATS

The renal clearance and urinary excretion of ciprofloxacin were investigated in eight healthy female goats. In each animal, ciprofloxacin was administered intramuscularly at the rate of 5 mg/kg body weight. Following drug administration, blood and urine samples were collected at different time intervals and analyzed for ciprofloxacin and creatinine. High performance liquid chromatography (HPLC) was used to determine the drug concentration in the plasma and urine. The value of diuresis after single administration of ciprofloxacin was 0.073 ± 0.014 ml/min/kg. Mean (± SE) values for renal clearance of creatinine and ciprofloxacin were 1.870 ± 0.385 and 0.982 ± 0.166 ml/min/kg, respectively. The ratio between the renal clearance of ciprofloxacin and that of creatinine remained less than one, which was indicative of back diffusion. The mean (± SE) value for the cumulative percent of ciprofloxacin dose excreted at 10 hours following its intramuscular administration was 13.03 ± 2.07. Based on these results, it was evident that besides glomerular filtration, renal handling of drug involved back diffusion also. It was concluded that in local goats glomerular filtration rate (GFR) was lower than that reported for their foreign counterparts

17-(Pyrimidin-2-yl)-8,16-dioxa-17-aza­tetra­cyclo­[7.7.1.02,7.010,15]hepta­deca-2,4,6,10,12,14-hexa­ene

In the title compound, C18H13N3O2, the benzene rings form a dihedral angle of 78.49 (9)°. The dihedral angles between the benzene rings and the pyrimidine ring are 76.53 (10) and 27.73 (11)°. The two cis-fused six-membered heterocyclic rings adopt half-chair confirmations. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, forming chains parallel to the b axis

Partly standing internal tides in a dendritic submarine canyon observed by an ocean glider

An autonomous ocean glider is used to make the first direct measurements of internal tides within Whittard Canyon, a large, dendritic submarine canyon system that incises the Celtic Sea continental slope and a site of high benthic biodiversity. This is the first time a glider has been used for targeted observations of internal tides in a submarine canyon. Vertical isopycnal displacement observations at different stations fit a one-dimensional model of partly standing semidiurnal internal tides – comprised of a major, incident wave propagating up the canyon limbs and a minor wave reflected back down-canyon by steep, supercritical bathymetry near the canyon heads. The up-canyon internal tide energy flux in the primary study limb decreases from 9.2 to 2.0 kW m−1 over 28 km (a dissipation rate of View the MathML source), comparable to elevated energy fluxes and internal tide driven mixing measured in other canyon systems. Within Whittard Canyon, enhanced mixing is inferred from collapsed temperature-salinity curves and weakened dissolved oxygen concentration gradients near the canyon heads. It has previously been hypothesised that internal tides impact benthic fauna through elevated near-bottom current velocities and particle resuspension. In support of this, we infer order 20 cm s−1 near-bottom current velocities in the canyon and observe high concentrations of suspended particulate matter. The glider observations are also used to estimate a 1 °C temperature range and 12 μmol kg−1 dissolved oxygen concentration range, experienced twice a day by organisms on the canyon walls, due to the presence of internal tides. This study highlights how a well-designed glider mission, incorporating a series of tide-resolving stations at key locations, can be used to understand internal tide dynamics in a region of complex topography, a sampling strategy that is applicable to continental shelves and slopes worldwide