2,986 research outputs found

    The injured eye – practical management guidelines and referral criteria for the rural doctor

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    Ocular trauma encompasses a wide spectrum of mechanisms and presentations, affecting the orbit, globe of the eye, optic nerve and adnexae. The causative injuries range from the relatively superficial to those that threaten sight. The rural doctor plays a vital role in the initial management of patients with ocular trauma and his/her decisions and treatment can influence the patient's final visual outcome. This article serves to classify ocular trauma and to provide management guidelines for treating minor trauma and initiating proper care for injuries that require referral to specialist ophthalmologists.For full text, click here:SA Fam Pract 2006;48(7):39-4

    Vitamin C in human health and disease is still a mystery ? An overview

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    Ascorbic acid is one of the important water soluble vitamins. It is essential for collagen, carnitine and neurotransmitters biosynthesis. Most plants and animals synthesize ascorbic acid for their own requirement. However, apes and humans can not synthesize ascorbic acid due to lack of an enzyme gulonolactone oxidase. Hence, ascorbic acid has to be supplemented mainly through fruits, vegetables and tablets. The current US recommended daily allowance (RDA) for ascorbic acid ranges between 100–120 mg/per day for adults. Many health benefits have been attributed to ascorbic acid such as antioxidant, anti-atherogenic, anti-carcinogenic, immunomodulator and prevents cold etc. However, lately the health benefits of ascorbic acid has been the subject of debate and controversies viz., Danger of mega doses of ascorbic acid? Does ascorbic acid act as a antioxidant or pro-oxidant ? Does ascorbic acid cause cancer or may interfere with cancer therapy? However, the Panel on dietary antioxidants and related compounds stated that the in vivo data do not clearly show a relationship between excess ascorbic acid intake and kidney stone formation, pro-oxidant effects, excess iron absorption. A number of clinical and epidemiological studies on anti-carcinogenic effects of ascorbic acid in humans did not show any conclusive beneficial effects on various types of cancer except gastric cancer. Recently, a few derivatives of ascorbic acid were tested on cancer cells, among them ascorbic acid esters showed promising anticancer activity compared to ascorbic acid. Ascorbyl stearate was found to inhibit proliferation of human cancer cells by interfering with cell cycle progression, induced apoptosis by modulation of signal transduction pathways. However, more mechanistic and human in vivo studies are needed to understand and elucidate the molecular mechanism underlying the anti-carcinogenic property of ascorbic acid. Thus, though ascorbic acid was discovered in 17(th )century, the exact role of this vitamin/nutraceutical in human biology and health is still a mystery in view of many beneficial claims and controversies

    Simultaneous multi-frequency single pulse observations of pulsars

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    We performed simultaneous observations at 326.5 MHz with the Ooty Radio Telescope and at 326, 610 and 1308 MHz with the Giant Meterwave Radio Telescope for a sample of 12 pulsars, where frequency dependent single pulse behaviour was reported. The single pulse sequences were analysed with fluctuation analysis, sensitive to both the average fluctuation properties (using longitude resolved fluctuation spectrum and two-dimensional fluctuation spectrum) as well as temporal changes in these (using sliding two-dimensional fluctuation spectrum ) to establish concurrent changes in subpulse drifting over the multiple frequencies employed. We report subpulse drifting in PSR J0934−-5249 for the first time. We also report pulse nulling measurements in PSRs J0934−-5249, B1508+55, J1822−-2256, B1845−-19 and J1901−-0906 for the first time. Our measurements of subpulse drifting and pulse nulling for the rest of the pulsars are consistent with previously reported values. Contrary to previous belief, we find no evidence for a frequency dependent drift pattern in PSR B2016+28 implied by non-simultaneous observations by Oster et al. (1977). In PSRs B1237+25, J1822−-2256, J1901−-0906 and B2045−-16, our longer and more sensitive observations reveal multiple drift rates with distinct P3. We increase the sample of pulsars showing concurrent nulling across multiple frequencies by more than 100 percent, adding 4 more pulsars to this sample. Our results confirm and further strengthen the understanding that the subpulse drifting and pulse nulling are broadband consistent with previous studies (Gajjar et al. 2014a; Rankin 1986; Weltevrede et al. 2007) and are closely tied to physics of polar gap.Comment: 22 pages, 44 figures, Single pulse studies of pulsars, accepted by A&

    PONDER - A Real time software backend for pulsar and IPS observations at the Ooty Radio Telescope

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    This paper describes a new real-time versatile backend, the Pulsar Ooty Radio Telescope New Digital Efficient Receiver (PONDER), which has been designed to operate along with the legacy analog system of the Ooty Radio Telescope (ORT). PONDER makes use of the current state of the art computing hardware, a Graphical Processing Unit (GPU) and sufficiently large disk storage to support high time resolution real-time data of pulsar observations, obtained by coherent dedispersion over a bandpass of 16 MHz. Four different modes for pulsar observations are implemented in PONDER to provide standard reduced data products, such as time-stamped integrated profiles and dedispersed time series, allowing faster avenues to scientific results for a variety of pulsar studies. Additionally, PONDER also supports general modes of interplanetary scintillation (IPS) measurements and very long baseline interferometry data recording. The IPS mode yields a single polarisation correlated time series of solar wind scintillation over a bandwidth of about four times larger (16 MHz) than that of the legacy system as well as its fluctuation spectrum with high temporal and frequency resolutions. The key point is that all the above modes operate in real time. This paper presents the design aspects of PONDER and outlines the design methodology for future similar backends. It also explains the principal operations of PONDER, illustrates its capabilities for a variety of pulsar and IPS observations and demonstrates its usefulness for a variety of astrophysical studies using the high sensitivity of the ORT.Comment: 25 pages, 14 figures, Accepted by Experimental Astronom

    Detection of long nulls in PSR B1706−-16, a pulsar with large timing irregularities

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    Single pulse observations, characterizing in detail, the nulling behaviour of PSR B1706−-16 are being reported for the first time in this paper. Our regular long duration monitoring of this pulsar reveals long nulls of 2 to 5 hours with an overall nulling fraction of 31±\pm2\%. The pulsar shows two distinct phases of emission. It is usually in an active phase, characterized by pulsations interspersed with shorter nulls, with a nulling fraction of about 15 \%, but it also rarely switches to an inactive phase, consisting of long nulls. The nulls in this pulsar are concurrent between 326.5 and 610 MHz. Profile mode changes accompanied by changes in fluctuation properties are seen in this pulsar, which switches from mode A before a null to mode B after the null. The distribution of null durations in this pulsar is bimodal. With its occasional long nulls, PSR B1706−-16 joins the small group of intermediate nullers, which lie between the classical nullers and the intermittent pulsars. Similar to other intermediate nullers, PSR B1706−-16 shows high timing noise, which could be due to its rare long nulls if one assumes that the slowdown rate during such nulls is different from that during the bursts.Comment: Accepted for publication in MNRA

    Scatter broadening measurements of 124 pulsars at 327 MHz

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    We present the measurements of scatter broadening time-scales (τsc\tau_{sc}) for 124 pulsars at 327 MHz, using the upgraded Ooty Radio Telescope (ORT). These pulsars lie in the dispersion measure range of 37 −- 503 pc cm−3^{-3} and declination (δ\delta) range of −-57∘<δ<60∘^{\circ} < \delta< 60^{\circ}. New τsc\tau_{sc} estimates for 58 pulsars are presented, increasing the sample of all such measurements by about 40% at 327 MHz. Using all available τsc\tau_{sc} measurements in the literature, we investigate the dependence of τsc\tau_{sc} on dispersion measure. Our measurements, together with previously reported values for τsc\tau_{sc}, affirm that the ionized interstellar medium upto 3 kpc is consistent with Kolmogorov spectrum, while it deviates significantly beyond this distance.Comment: 19 pages, 4 figures, accepted for publication in Ap

    Evaluation of Turmeric (Curcuma longa L.) Varieties for Rainfed Cultivation

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    Field experiments were carried out for two years at Agricultural Research Station, Seethampeta, Srikakulam Dist., Andhra Pradesh, to identify suitable turmeric cultivars for tribal areas of North Coastal Andhra Pradesh for rainfed cultivation. Ten cultivars were screened for their performance for comparison with the most popular local cultivar, 'Seethampeta local'. All the cultivars tested outperformed the local cultivar. Cultivars PTS-24 and CLL-326 were better in terms of plant height (93.43cm and 92.70cm, respectively) and mean number of tillers / plant (2.16 and 2.21 respectively). Per cent curing was highest in PTS-38 (28.5), followed by PTS-24 (25.7) and CLL-326 (25.2). Cultivars PTS-24 and CLL-326 recorded highest mean yield of both fresh and cured rhizomes. Yield of fresh rhizomes was positively correlated to number of tillers and number of leaves, while, yield of cured rhizomes was significantly influenced by per cent curing and number of leaves. Cultivars PTS-24 and CLL-326 recorded highest mean yield (23.08 t ha-1&nbsp;and 22.93 t ha-1, respectively) and were identified as suitable varieties for rainfed cultivation in tribal areas of North Coastal Andhra Pradesh

    Detection of radio emission from the gamma-ray pulsar J1732-3131 at 327 MHz

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    Although originally discovered as a radio-quiet gamma-ray pulsar, J1732-3131 has exhibited intriguing detections at decameter wavelengths. We report an extensive follow-up of the pulsar at 327 MHz with the Ooty radio telescope. Using the previously observed radio characteristics, and with an effective integration time of 60 hrs, we present a detection of the pulsar at a confidence level of 99.82%. The 327 MHz mean flux density is estimated to be 0.5-0.8 mJy, which establishes the pulsar to be a steep spectrum source and one of the least-luminous pulsars known to date. We also phase-aligned the radio and gamma-ray profiles of the pulsar, and measured the phase-offset between the main peaks in the two profiles to be 0.24±\pm0.06. We discuss the observed phase-offset in the context of various trends exhibited by the radio-loud gamma-ray pulsar population, and suggest that the gamma-ray emission from J1732-3131 is best explained by outer magnetosphere models. Details of our analysis leading to the pulsar detection, and measurements of various parameters and their implications relevant to the pulsar's emission mechanism are presented.Comment: 8 pages, 6 figures; Accepted for publication in MNRA
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