First hours of the GRB 030329 optical afterglow

We present the first results of the observations of the extremely bright optical afterglow of gamma-ray burst (GRB) 030329 with the 1.5m Russian-Turkish telescope RTT150 (TUBITAK National Observatory, Bakyrlytepe, Turkey). RTT150 was one of the first 1.5m-class telescopes pointed to the afterglow. Observations were started approximately 6 hours after the burst. During the first 5 hours of our observations the afterglow faded exactly as a power law with index -1.19+-0.01 in each of the BVRI Bessel filters. After that, in all BVRI filters simultaneously we observe a steepening of the power law light curve. The power law decay index smoothly approaches the value ~= -1.9, observed by other observatories later. This power law break occurs at t-t_0 =0.57 days and lasts for +-0.1 days. We observe no variability above the gradual fading with the upper limits 10--1% on time scales 0.1--1000s. Spectral flux distribution in four BVRI filters corresponds to the power law spectrum with spectral index \alpha=0.66+-0.01. The change of the power law decay index in the end of our observations can be interpreted as a signature of collimated ultrarelativistic jet. The afterglow flux distribution in radio, optical and x-rays is consistent with synchrotron spectrum. We continue our observations of this unique object with RTT150.Comment: Astronomy Letters, Vol. 29, No. 9, p. 573; 6 pages, 5 figures; pagination corrected; the original Russian version can be found at http://hea.iki.rssi.ru/~br/030329/pfh030329.pd

Observations of GRB 060526 Optical Afterglow with Russian-Turkish 1.5-m Telescope

We present the results of the photometric multicolor observations of GRB 060526 optical afterglow obtained with Russian-Turkish 1.5-m Telescope (RTT150, Mt. Bakirlitepe, Turkey). The detailed measurements of afterglow light curve, starting from about 5 hours after the GRB and during 5 consecutive nights were done. In addition, upper limits on the fast variability of the afterglow during the first night of observations were obtained and the history of afterglow color variations was measured in detail. In the time interval from 6 to 16 hours after the burst, there is a gradual flux decay, which can be described approximately as a power law with an index of -1.14+-0.02. After that the variability on the time scale \delta t < t is observed and the afterglow started to decay faster. The color of the afterglow, V-R=~0.5, is approximately the same during all our observations. The variability is detected on time scales up to \delta t/t =~ 0.0055 at \Delta F_\nu/F_\nu =~ 0.3, which violates some constraints on the variability of the observed emission from ultrarelativistic jet obtained by Ioka et al. (2005). We suggest to explain this variability by the fact that the motion of the emitting shell is no longer ultrarelativistic at this time.Comment: 6 pages, 7 figures, Astronomy Letters, 2007, 33, 797, The on-line data tables and the original text in Russian can be found at http://hea.iki.rssi.ru/grb/060526/indexeng.htm

Nanomechanical characterization by double-pass force-distance mapping

Cataloged from PDF version of article.We demonstrate high speed force–distance mapping using a double-pass scheme. The topography is measured in tapping mode in the first pass and this information is used in the second pass to move the tip over the sample. In the second pass, the cantilever dither signal is turned off and the sample is vibrated. Rapid (few kHz frequency) force–distance curves can be recorded with small peak interaction force, and can be processed into an image. Such a double-pass measurement eliminates the need for feedback during force–distance measurements. The method is demonstrated on self-assembled peptidic nanofibers

"Medicine is still against Black people": Mapping and visualising intersections of social inequalities, community mistrust, and vaccine hesitancy in online and physical spaces in the UK and US

Funded by the British Academy, this report is part of a research project entitled “Mapping and visualising intersections of social inequalities, community mistrust, and vaccine hesitancy in online and physical spaces in the UK and US”. The report investigates social, cultural, and political factors underlying vaccine hesitant beliefs and ideas among minoritised communities in the United Kingdom (UK) and the United States of America (US). The data is collected through interviews and focus groups with vaccine-hesitant individuals within various religiously, ethnically, and racially minoritised communities, interviews with medical practitioners, and through thematic analysis of vaccine communication in Twitter and Telegram during the COVID-19 pandemic

Transcriptomic changes triggered by ouabain in rat cerebellum granule cells: Role of α3- and α1-Na+,K+-ATPase-mediated signaling

It was shown previously that inhibition of the ubiquitous α1 isoform of Na+,K+-ATPase by ouabain sharply affects gene expression profile via elevation of intracellular [Na+]i/[K+]i ratio. Unlike other cells, neurons are abundant in the α3 isoform of Na+,K+-ATPase, whose affinity in rodents to ouabain is 104-fold higher compared to the α1 isoform. With these sharp differences in mind, we compared transcriptomic changes in rat cerebellum granule cells triggered by inhibition of α1- and α3-Na+,K+-ATPase isoforms. Inhibition of α1- and α3-Na+,K+-ATPase isoforms by 1 mM ouabain resulted in dissipation of transmembrane Na+ and K+ gradients and differential expression of 994 transcripts, whereas selective inhibition of α3-Na+,K+-ATPase isoform by 100 nM ouabain affected expression of 144 transcripts without any impact on the [Na+]i/[K+]i ratio. The list of genes whose expression was affected by 1 mM ouabain by more than 2-fold was abundant in intermediates of intracellular signaling and transcription regulators, including augmented content of Npas4, Fos, Junb, Atf3, and Klf4 mRNAs, whose upregulated expression was demonstrated in neurons subjected to electrical and glutamatergic stimulation. The role [Na+]i/[K+]i-mediated signaling in transcriptomic changes involved in memory formation and storage should be examined further

ANALYZING THE RETRIEVAL ACCURACY OF OPTICALLY ACTIVE WATER COMPONENTS FROM SATELLITE DATA UNDER VARYING IMAGE RESOLUTIONS

Water quality monitoring has a key role in maintaining a sustainable ecosystem and environmental health. To ensure consistent monitoring, remote sensing provides regular data acquisition with varying spatial resolutions. However, more accurate, and effective solutions can be achieved by integrating remote sensing data with in-situ measurements. This study investigates the integration of in-situ measurements with satellite data, which have different spectral and spatial resolutions, using linear and exponential regression models for four optically active components in the Gulf of Izmit. In this context, Sentinel-2 (S2) and PlanetScope SuperDove (PS) multispectral images, which were acquired on the same date, were used for the comparative analysis of the accurate mapping of chlorophyll-a (Chl-a), turbidity, Secchi disk depth (SDD) and total suspended matter (TSM) water quality parameters combined with simultaneously collected in-situ measurements. The models were evaluated using validation data, along with visual comparison, to assess their accuracy. The results indicate that, overall, exponential models provide more accurate results than linear models, except for the SDD parameter. Furthermore, models created with S2 data demonstrate better performance in retrieving water quality parameters for Chl-a, turbidity, and TSM, with R2 values of 0.71, 0.84, and 0.91, respectively. The linear model created with PS data stands out in the accurately mapping of SDD parameter. Nevertheless, the spatial distribution of these parameters using both satellite dataset exhibits a similar pattern throughout the gulf, which is under threat from significant terrestrial pollution sources, particularly in the eastern part

The Crossing Statistic: Dealing with Unknown Errors in the Dispersion of Type Ia Supernovae

We propose a new statistic that has been designed to be used in situations where the intrinsic dispersion of a data set is not well known: The Crossing Statistic. This statistic is in general less sensitive than `chi^2' to the intrinsic dispersion of the data, and hence allows us to make progress in distinguishing between different models using goodness of fit to the data even when the errors involved are poorly understood. The proposed statistic makes use of the shape and trends of a model's predictions in a quantifiable manner. It is applicable to a variety of circumstances, although we consider it to be especially well suited to the task of distinguishing between different cosmological models using type Ia supernovae. We show that this statistic can easily distinguish between different models in cases where the `chi^2' statistic fails. We also show that the last mode of the Crossing Statistic is identical to `chi^2', so that it can be considered as a generalization of `chi^2'.Comment: 14 pages, 5 figures. Paper restructured and extended and new interpretation of the method presented. New results concerning model selection. Treatment and error-analysis made fully model independent. References added. Accepted for publication in JCA

Role of free radicals in peptic ulcer and gastritis

Background/aims: It has been suggested that the free radicals are closely related with peptic ulcer disease and gastritis. Although many studies have been undertaken to clarify the role of oxygen-derived free radicals, most of them were carried out in animal models. The aim of this study was to assess the reactive oxygen species activity and the damage in Helicobacter pyloriinfected gastric mucosa in humans. Methods: In a total group of 42, there were fifteen cases of peptic ulcer, 14 cases of gastritis and 12 control subjects. Measurement of gastric mucosal malondialdehyde concentrations, which is the end - product of lipid peroxidation, was used to assess oxidative damage to membranes in patients with peptic ulcer and gastritis. Mucosal reduced glutathione glutathione concentrations were also measured in order to study whether reactive oxygen species generation affects levels of the antioxidant peptide, malondialdehyde and glutathione content was then measured in biopsies taken from the gastric antrum. Results: Tissue levels of glutathione were significantly (p <0.001) and malondialdehyde was higher (p<0.001) in patients with peptic ulcer compared to controls. In patients with gastritis, glutathione was also lower (p<0.001) and malondialdehyde higher (p<0.01). Conclusions: Depletion of gastric mucosal glutathione in cases with H.pylori positive peptic ulcer and gastritis may be caused by accumulation of free radicals that can initiate membrane damage by lipid peroxidation

Dynamics of porous and amorphous magnesium borohydride to understand solid state Mg-ion-conductors

Rechargeable solid-state magnesium batteries are considered for high energy density storage and usage in mobile applications as well as to store energy from intermittent energy sources, triggering intense research for suitable electrode and electrolyte materials. Recently, magnesium borohydride, Mg(BH$_{4}$)$_{2}$, was found to be an effective precursor for solid-state Mg-ion conductors. During the mechanochemical synthesis of these Mg-ion conductors, amorphous Mg(BH$_{4}$)$_{2}$ is typically formed and it was postulated that this amorphous phase promotes the conductivity. Here, electrochemical impedance spectroscopy of as-received γ-Mg(BH$_{4}$)$_{2}$ and ball milled, amorphous Mg(BH$_{4}$)$_{2}$ confirmed that the conductivity of the latter is ~2 orders of magnitude higher than in as-received γ-Mg(BH$_{4}$)$_{2}$ at 353 K. Pair distribution function (PDF) analysis of the local structure shows striking similarities up to a length scale of 5.1 Å, suggesting similar conduction pathways in both the crystalline and amorphous sample. Up to 12.27 Å the PDF indicates that a 3D net of interpenetrating channels might still be present in the amorphous phase although less ordered compared to the as-received γ-phase. However, quasi elastic neutron scattering experiments (QENS) were used to study the rotational mobility of the [BH$_{4}$] units, revealing a much larger fraction of activated [BH$_{4}$] rotations in amorphous Mg(BH$_{4}$)$_{2}$. These findings suggest that the conduction process in amorphous Mg(BH$_{4}$)$_{2}$ is supported by stronger rotational mobility, which is proposed to be the so-called “paddle-wheel” mechanism

Analysis of optical light curves for the components of the gravitationally lensed quasar SBS 1520+530 based on observations with the 1.5-m RTT-150 telescope in 2001-2005

We present the R c-band light curves for components A and B of the gravitationally lensed quasar SBS 1520+530 obtained during 2001-2005 with the 1.5-m Russian-Turkish Telescope (RTT-150) at the TUBITAK National Observatory (Turkey). Based on an analysis of the data for the period 2001-2002, we have estimated the time delay of the brightness fluctuations between components A and B of the quasar to be 128 days. This time delay agrees with its previously published values for the periods 1999-2001 and 2003-2004. Using all of the published data on the brightnesses of components A and B of SBS 1520+530 for the 6-year period, we have found at least two microlensing events. One event has the pattern of a long-term linear trend; the duration of the other event is several hundred days. © Pleiades Publishing, Inc., 2006