Prevelence and causes of visual impairment and blindness in older adults in an area of India with a high cataract surgical rate.

BACKGROUND: The cataract surgical rate (CSR) in Gujarat, India is reported to be above 10,000 per million population. This study was conducted to investigate the prevalence and causes of vision impairment/blindness among older adults in a high CSR area. METHODS: Geographically defined cluster sampling was used in randomly selecting persons >or= 50 years of age in Navsari district. Subjects in 35 study clusters were enumerated and invited for measurement of presenting and best-corrected visual acuity and an ocular examination. The principal cause was identified for eyes with presenting visual acuity < 20/32. RESULTS: A total of 5158 eligible persons were enumerated and 4738 (91.9%) examined. Prevalence of presenting visual impairment < 20/63 to 20/200 in the better eye was 29.3% (95% confidence interval [CI]: 27.5-31.2) and 13.5% (95% CI: 12.0-14.9) with best correction. The prevalence of presenting bilateral blindness (< 20/200) was 6.9% (95% CI: 5.7-8.1), and 3.1% (95% CI: 2.5-3.7) with best correction. Presenting and best-corrected blindness were both associated with older age and illiteracy; gender and rural/urban residence were not significant. Cataract in one or both eyes was the main cause of bilateral blindness (82.6%), followed by retinal disorders (8.9%). Cataract (50.3%) and refractive error (35.4%) were the main causes in eyes with vision acuity < 20/63 to 20/200, and refractive error (86.6%) in eyes with acuity < 20/32 to 20/63. CONCLUSIONS: Visual impairment and blindness is a significant problem among the elderly in Gujarat. Despite a reportedly high CSR, cataract remains the predominant cause of blindness

Theoretical spectroscopic studies of the atomic transitions and lifetimes of low-lying states in Ti IV

The astrophysically important electric quadrupole (E2) and magnetic dipole (M1) transitions for the low-lying states of triply ionized titanium (Ti IV) are calculated very accurately using a state-of-art all-order many-body theory called Coupled Cluster (CC) theory in the relativistic frame-work. Different many-body correlations of the CC theory has been estimated by studying the core and valence electron excitations to the unoccupied states. The calculated excitation energies of different states are in very good agreement with the measurements. Also we compare our calculated electric dipole (E1) transition amplitudes of few transitions with recent many-body calculations by different groups. We have also carried out the calculations for the lifetimes of the low-lying states of Ti IV. A long lifetime is found for the first excited 3d$^{2}D_{5/2}$ state, which suggested that Ti IV may be one of the useful candidates for many important studies. Most of the results reported here are not available in the literature, to the best of our knowledge.Comment: 15 pages submitted to J. Phys.

Kodaikanal Digitized White-light Data Archive (1921-2011): Analysis of various solar cycle features

Long-term sunspot observations are key to understand and predict the solar activities and its effects on the space weather.Consistent observations which are crucial for long-term variations studies,are generally not available due to upgradation/modifications of observatories over the course of time. We present the data for a period of 90 years acquired from persistent observation at the Kodaikanal observatory in India. We use an advanced semi-automated algorithm to detect the sunspots form each calibrated white-light image. Area, longitude and latitude of each of the detected sunspots are derived. Implementation of a semi-automated method is very necessary in such studies as it minimizes the human bias in the detection procedure. Daily, monthly and yearly sunspot area variations obtained from the Kodaikanal, compared well with the Greenwich sunspot area data. We find an exponentially decaying distribution for the individual sunspot area for each of the solar cycles. Analyzing the histograms of the latitudinal distribution of the detected sunspots, we find Gaussian distributions, in both the hemispheres, with the centers at $\sim$15$^{\circ}$ latitude. The height of the Gaussian distributions are different for the two hemispheres for a particular cycle. Using our data, we show clear presence of Waldmeier effect which correlates the rise time with the cycle amplitude. Using the wavelet analysis, we explored different periodicities of different time scales present in the sunspot area times series.Comment: Accepted for Publication in A&

Holy Ganga and the mighty Amazon

River Ganga is the largest and most sacred river of India. As compared to the mighty Amazon, it is very small but exerts great influence on the socio-cultural life and economy of lndia. Though the basin of River Ganga has been the cradle of human civilisation for several millennia, the rapid growth of human population, coupled with urbanisation, intensive agriculture and industrialization, has resulted in rapid deterioration of water quality and loss of aquatic biodiversity during past few decades. Some salient features of River Ganga are presented here and compared with those of River Amazon, in tribute to Professor Sioli who pioneered studies along the "Rio Amazonas"

Evolution of crystalline electric field effects, superconductivity, and heavy fermion behavior in the specific heat of Pr(Os1−x_{1-x}Rux_x)4_4Sb12_{12}

Specific heat $C(T)$ measurements were made on single crystals of the superconducting filled skutterudite series Pr(Os$_{1-x}$Ru$_x$)$_4$Sb$_{12}$ down to 0.6 K. Crystalline electric field fits in the normal state produced parameters which were in agreement with previous measurements. Bulk superconductivity was observed for all values of the Ru concentration $x$ with transition temperatures consistent with previous experiments, confirming a minimum in $T_{c}$ at $x=0.6$. The $C(T)$ data below $T_{c}$ appear to be more consistent with power law behavior for $x=0$ (PrOs$_4$Sb$_{12}$), and with exponential behavior for $0.05 \leq x \leq 0.2$. An enhanced electronic specific heat coefficient $\gamma$ was observed for $x \leq 0.4$, further supporting $x \simeq 0.6$ as a critical concentration where the physical properties abruptly change. Significant enhancement of $\Delta C/T_{c}$ above the weak coupling value was only observed for $x=0$ and $x=0.05$.Comment: 16 pages, 5 figures, submitted to Physical Review B. v2: text added and figures modifie

The Origin of X-shaped Radio Galaxies: Clues from the Z-symmetric Secondary Lobes

Existing radio images of a few X-shaped radio galaxies reveal Z-symmetric morphologies in their weaker secondary lobes which cannot be naturally explained by either the galactic merger or radio-lobe backflow scenarios, the two dominant models for these X-shaped radio sources. We show that the merger picture can explain these morphologies provided one takes into account that, prior to the coalescence of their supermassive black holes, the smaller galaxy releases significant amounts of gas into the ISM of the dominant active galaxy. This rotating gas, whose angular momentum axis will typically not be aligned with the original jets, is likely to provide sufficient ram pressure at a distance ~10 kpc from the nucleus to bend the extant jets emerging from the central engine, thus producing a Z-symmetry in the pair of radio lobes. Once the two black holes have coalesced some 10^7 yr later, a rapid reorientation of the jets along a direction close to that of the orbital angular momentum of the swallowed galaxy relative to the primary galaxy would create the younger primary lobes of the X-shaped radio galaxy. This picture naturally explains why such sources typically have powers close to the FR I/II break. We suggest that purely Z-symmetric radio sources are often en route to coalescence and the concomitant emission of substantial gravitational radiation, while X-shaped ones have already merged and radiated.Comment: 12 pages, 1 compressed figure; accepted for publication in ApJ Letter