High frequency study of FRB 20180916B using the 100-m Effelsberg radio telescope

FRB 20180916B is a repeating fast radio burst (FRB) with an activity period of 16.33 days. In previous observations ranging from $\sim 150-1400$ MHz, the activity window was found to be frequency dependent, with lower frequency bursts occurring later. In this work, we present the highest-frequency detections of bursts from this FRB, using the 100-m Effelsberg Radio Telescope at 4$-$8 GHz. We present the results from two observing campaigns. We performed the first campaign over an entire activity period which resulted in no detections. The second campaign was in an active window at 4$-$8 GHz which we predicted from our modelling of chromaticity, resulting in eight burst detections. The bursts were detected in a window of 1.35 days, 3.6 days preceding the activity peak seen by CHIME, suggesting the chromaticity extends to higher frequency. The detected bursts have narrower temporal widths and larger spectral widths compared to lower frequencies. All of them have flat polarization position angle sweeps and high polarization fractions. The bursts also exhibit diffractive scintillation due to the Milky Way, following a $f^{3.90\pm0.05}$ scaling, and vary significantly over time. We find that burst rate across frequency scales as $f^{-2.6\pm0.2}$. Lastly, we examine implications of the frequency dependency on the source models.Comment: 11 pages, 8 figures, comments welcome, submitted to MNRA

Modelling Annual Scintillation Velocity Variations of FRB 20201124A

Compact radio sources exhibit scintillation, an interference pattern arising from propagation through inhomogeneous plasma, where scintillation patterns encode the relative distances and velocities of the source, scattering material, and Earth. In Main et al. 2022, we showed that the scintillation velocity of the repeating fast radio burst FRB20201124A can be measured by correlating pairs of burst spectra, and suggested that the scattering was nearby the Earth at $\sim0.4\,$kpc from the low values of the scintillation velocity and scattering timescale. In this work, we have measured the scintillation velocity at 10 epochs spanning a year, observing an annual variation which strongly implies the screen is within the Milky Way. Modelling the annual variation with a 1D anisotropic or 2D isotropic screen results in a screen distance $d_{l} = 0.24\pm0.04\,$pc or $d_{l} = 0.37\pm0.07\,$pc from Earth respectively, possibly associated with the Local Bubble or the edge of the Orion-Eridanus Superbubble. Continued monitoring, and using measurements from other telescopes particularly at times of low effective velocity will help probe changes in screen properties, and distinguish between screen models. Where scintillation of an FRB originates in its host galaxy or local environment, these techniques could be used to detect orbital motion, and probe the FRB's local ionized environment.Comment: 5 pages, 5 Figures, submitted to MNRAS Letter

Median statistics estimates of Hubble and Newton's Constant

Robustness of any statistics depends upon the number of assumptions it makes about the measured data. We point out the advantages of median statistics using toy numerical experiments and demonstrate its robustness, when the number of assumptions we can make about the data are limited. We then apply the median statistics technique to obtain estimates of two constants of nature, Hubble Constant (H0) and Newton's Gravitational Constant(G), both of which show significant differences between different measurements. For H0, we update the analysis done by Chen and Ratra (2011) and Gott et al. (2001) using 576 measurements. We find after grouping the different results according to their primary type of measurement, the median estimates are given by H0=72.5+2.5−8 km/sec/Mpc with errors corresponding to 95% c.l. (2σ) and G=6.674702+0.0014−0.0009×10−11Nm2kg−2 corresponding to 68% c.l. (1σ)

Development of an experimental model of a decellularized kidney scaffold by perfusion mode and analyzing the three-dimensional extracellular matrix architecture by edge detection method

Renal transplant is treatment of choice for the patients with end stage renal disease. The kidney transplants are expensive and there are risks of immunological and infectious complications. We planned to develop an in vitro decellularized kidney scaffold model using sheep kidney. Kidney decellularization was carried out by perfusing chemical detergents such as sodium dodecyl sulfate (SDS), SDS and trypsin, and SDS and ethylenediaminetetraacetic acid solvent solution. Complete kidney was decellularized in 5 days by perfusing various chemical detergents in time-dependent intervals. Histological finding revealed the complete removal of cellular material in various regions of renal corpuscle, distal convoluted tubules, other cortex and medulla region. Details of interlobular veins and arteries were seen through naked eyes after trypan blue dye injection. We used edge detection technique for developing a three-dimensional (3-D) image (Image J software) for nephrological vasculature constructed of decellularized kidney scaffold specimen. This technique opens a gateway for the whole organ decellularization by perfusion technology and further imaging of its 3-D extracellular matrix texture by edge detection technique software

The London 2012 Summer Olympic Games - an analysis of usage of the Olympic Village ‘Polyclinic’ by competing athletes

AbstractBackground The London 2012 Summer Olympic Games involved 10 568 elite athletes representing 204 competing nations. To manage the varied healthcare needs of this diverse population, a Polyclinic was constructed in the athletes’ village.Aim This work aims to summarise the usage of the Polyclinic by competing athletes and the facilities available to them.Methods All Polyclinic encounters were entered into a database from which data were exported for the time frame 28 July–12 August 2012, inclusive to cover the first to last full day of competition. Only Polyclinic data involving accredited athletes were analysed. All types of encounters were collected for analysis, not just sports-related issues.Results There were a total of 3220 encounters within the Polyclinic. This figure combines medical consultations, radiology/pathology investigations and prescriptions dispensed. Of these 3220 encounters, there were 2105 medical consultations; musculoskeletal comprised the greatest number (52%), followed by dental (30%) and ophthalmic (9%). The most frequently used imaging modality was MRI and diagnostic CT was used the least. After correction for multiple entries, Africa provided the largest proportion of athletes attending the Polyclinic (44%) and Europe the least (9%). Peak usage of all facilities was seen around days 9 and 10 of competition, reflecting the busiest time of the competition and the largest number of athletes in the village.Conclusions The Polyclinic managed a wide variety of both sports-related and non-sports-related injuries and illnesses. The breadth of specialists available for consultation was appropriate as was the ease of access to them. The radiology department was able to satisfy the demand, as were the pharmacy and pathology services. We would recommend a similar structure of facilities and available expertise in one clinic when planning future mass participation sporting events

Mutagenicity and Acute Oral Toxicity Test for Herbal Poultry Feed Supplements

Herbal products are being used and trusted globally for thousands of years for their health benefits and limited side effects. Globally, a general belief amongst the consumers is that herbal supplements are always safe because they are “natural.” But later, research reveals that they may not be safe. This raises concern on their safety and implications for their use as feed supplement or medicine. Toxicity testing can reveal some of the risks that may be associated with use of herbs, therefore avoiding potential harmful effects. The present study was designed to investigate five poultry feed supplements (PFS), EGMAX® (to revitalize ovarian activity), FEED-X™ (feed efficiency enhancer), KOLIN PLUS™ (natural replacer of synthetic choline chloride), PHYTOCEE® (natural defence enhancer), and STODI® (to prevent and control loose droppings), for their possible mutagenicity and toxicity. Bacterial reverse mutation (BRMT) and acute oral toxicity tests were employed to assess the PFS for their possible mutagenicity and toxicity. Results indicated that the PFS were devoid of mutagenic effects in BRMT and showed higher safety profile in rodent acute oral toxicity test