Measurement of polarized light provides a direct probe of magnetic fields in collimated outflows (jets) of relativistic plasma from accreting stellar-mass black holes at cosmological distances. These ...outflows power brief and intense flashes of prompt gamma-rays known as Gamma Ray Bursts (GRBs), followed by longer-lived afterglow radiation detected across the electromagnetic spectrum. Rapid-response polarimetric observations of newly discovered GRBs have probed the initial afterglow phase. Linear polarization degrees as high as Π∼30% are detected minutes after the end of the prompt GRB emission, consistent with a stable, globally ordered magnetic field permeating the jet at large distances from the central source. In contrast, optical and gamma-ray observations during the prompt phase led to discordant and often controversial results, and no definitive conclusions on the origin of the prompt radiation or the configuration of the magnetic field could be derived. Here we report the detection of linear polarization of a prompt optical flash that accompanied the extremely energetic and long-lived prompt gamma-ray emission from GRB 160625B. Our measurements probe the structure of the magnetic field at an early stage of the GRB jet, closer to the central source, and show that the prompt GRB phase is produced via fast cooling synchrotron radiation in a large-scale magnetic field advected from the central black hole and distorted from dissipation processes within the jet.
We present optical and near-infrared (NIR) photometry of 28 gamma-ray bursts (GRBs) detected by the Swift satellite and rapidly observed by the Reionization and Transients Infrared/Optical (RATIR) ...camera. We compare the optical flux at fiducial times of 5.5 and 11 h after the high-energy trigger to that in the X-ray regime to quantify optical darkness. 46 ± 9 per cent (13/28) of all bursts in our sample and 55 ± 10 per cent (13/26) of long GRBs are optically dark, which is statistically consistently with previous studies. Fitting RATIR optical and NIR spectral energy distributions of 19 GRBs, most (6/7) optically dark GRBs either occur at high redshift (z > 4.5) or have a high dust content in their host galaxies (A
V > 0.3). Performing Kolmogorov–Smirnov tests, we compare the RATIR sample to those previously presented in the literature, finding our distributions of redshift, optical darkness, host dust extinction and X-ray-derived column density to be consistent. The one reported discrepancy is with host galaxy dust content in the BAT6 sample, which appears inconsistent with our sample and other previous literature. Comparing X-ray-derived host galaxy hydrogen column densities to host galaxy dust extinction, we find that GRBs tend to occur in host galaxies with a higher metal-to-dust ratio than our own Galaxy, more akin to the Large and Small Magellanic Clouds. Finally, to mitigate time evolution of optical darkness, we measure βOX, rest at a fixed rest-frame time, t
rest = 1.5 h and fixed rest-frame energies in the X-ray and optical regimes. Choosing to evaluate optical flux at λrest = 0.25 μm, we remove high redshift as a source of optical darkness, demonstrating that optical darkness must result from either high redshift, dust content in the host galaxy along the GRB sight line, or a combination of the two.
The transition from prompt to afterglow emission is one of the most exciting and least understood phases in gamma-ray bursts (GRBs). Correlations among optical, X-ray, and gamma-ray emission in GRBs ...have been explored, to attempt to answer whether the earliest optical emission comes from internal and/or external shocks. We present optical photometric observations of GRB 180325A collected with the TAROT and RATIR ground-based telescopes. These observations show two strong optical flashes with separate peaks at ∼50 and ∼120 s, followed by a temporally extended optical emission. We also present X-rays and gamma-ray observations of GRB 180325A, detected by the Burst Alert Telescope and X-ray Telescope, on the Neil Gehrels Swift observatory, which both observed a narrow flash at ∼80 s. We show that the prompt gamma-ray and X-ray early emission shares similar temporal and spectral features consistent with internal dissipation within the relativistic outflow (e.g., by internal shocks or magnetic reconnection), while the early optical flashes are likely generated by the reverse shock that decelerates the ejecta as it sweeps up the external medium.
•Nuclear abnormalities frequency was higher in diabetic patients than in controls.•No differences between type of diabetes, control, smoking, age or sex was observed.•Uncontrolled diabetic patients ...showed a greater frequency of micronuclei.•Nuclear abnormalities diminish after folic acid intake in diabetic patients.•Folate decreases frequencies of cells with MN, BN, PYK, KR, KR+CC, KL, and NBUD.
Diabetes mellitus (DM) is characterized by high blood glucose. Excessive production of free radicals may cause oxidative damage to DNA and other molecules, leading to complications of the disease. It may be possible to delay or reduce such damage by administration of antioxidants such as folic acid (FA). The objective of this study was to determine the effect of FA on nuclear abnormalities (NAs) in the oral mucosa of patients with DM. NAs (micronucleated cells, binucleated cells, pyknotic nuclei, karyorrhexis, karyolysis, abnormally condensed chromatin, and nuclear buds) were analyzed in 2000 cells from 45 healthy individuals (control group) and 55 patients with controlled or uncontrolled type I or II DM; 35 patients in the latter group were treated with FA. Samples were taken from the FA group before and after treatment. An increased rate of NAs was found in patients with DM in comparison with that of the control group (P<0.001). FA supplementation in patients with DM reduced the frequency of NAs (20.4±8.0 before treatment vs. 10.5±5.2 after treatment; P<0.001). The type I and type II DM and controlled and uncontrolled DM subgroups were analyzed in terms of sex, age, and smoking habit. The significantly reduced frequencies of buccal mucosa cells with micronuclei, binucleation, pyknosis, karyorrhexis, karyorrhexis+abnormally condensed chromatin, karyolysis, and nuclear buds produced by FA supplementation in DM patients (P<0.02) are consistent with the idea that free radicals are responsible for the increased frequency of NAs in DM patients.
The aim of this investigation was to determine the frequency and association of the variants rs4817415, rs2070424, and rs1041740 of the SOD1 gene in healthy women and breast cancer (BC) patients.
...Genomic DNA samples from 146 healthy women and 130 patients with BC were analyzed.
GG genotype (OR 2.54, 95% CI 1.31-4.91, p = 0.0073) and the G allele (OR 1.37, 95% CI 1.09-1.73, p = 0.007) of the rs2070424 variant and CC genotype (OR 1.67, 95% CI 1.04-0.2.70, p = 0.0444) and allele C (OR 1.58, 95% CI 1.09-2.29, p = 0.0183) of the rs1041740 variant of SOD1 gene were associated as risk factors for BC susceptibility relative to the control group. Study groups comparison of the stratification by menopausal status showed an association of susceptibility to BC risk with carriers of the GG genotype (OR 2.9, 95% CI 1.11-7.81, p = 0.042) of the rs2070424 variant and with the premenopausal status of the study group and the TT (OR 2.89, 95% CI 1.73-4.85, p = 0.001) genotype of the rs1041740 variant. Furthermore, differences were observed in the patients with BC who were carriers of the CC genotype of the rs4817415 variant with elevated Ki-67 (≥ 20%) and who presented lymph node metastasis and stage III-IV BC (p<0.05). Two common haplotypes were identified in the study groups: CAC (protective factor), and CGC (risk factor) (p<0.05).
The rs2070424 and rs1041740 variants of the SOD1 gene and the CGC haplotype were associated as risk susceptibility factors of BC in this sample analyzed.
Background and Objective
Periodontal disease is a chronic bacterial infection characterized by connective tissue breakdown and alveolar bone destruction because of inflammatory and immune response ...caused by periodontopathogens and long‐term release of reactive oxygen species. A high number of reactive oxygen species result in periodontal tissue damage through multiple mechanisms such as lipid peroxidation, protein denaturation and DNA damage. The aim of this study was to evaluate DNA and oxidative damage in subjects with chronic or aggressive periodontitis and healthy controls.
Material and Methods
Buccal mucosa cells and whole saliva were collected from 160 subjects, who were divided into three groups: subjects with chronic periodontitis (CP) (n = 58), subjects with aggressive periodontitis (AgP) (n = 42) and a control group (n = 60). DNA damage was determined by counting micronuclei (MN) and nuclear abnormalities (NAs) in exfoliated cells, including binucleated cells, cells with nuclear buds and karyolitic, karyorrhectic, condensed chromatin and pyknotic cells. The degree of oxidative stress was determined by quantifying 8‐hydroxy‐2′‐deoxyguanosine (8‐OHdG) in whole saliva.
Results
Subjects with CP or AgP presented significantly more ( p < 0.05) MN and NAs and higher levels of 8‐OHdG ( p < 0.05) compared with the control group.
Conclusion
Our results indicate that subjects with periodontitis (CP or AgP) exhibited an increase in the frequency of MN, NAs and 8‐OHdG, which is directly related to DNA damage. In addition, a positive correlation exists between oxidative stress produced by periodontitis disease and MN.
The early optical emission of gamma-ray bursts (GRBs) gives an opportunity to understand the central engine and first stages of these events. About 30% of GRBs present flares whose origin is still a ...subject of discussion. We present optical photometry of GRB 180620A with the COATLI telescope and RATIR instrument. COATLI started to observe from the end of prompt emission at T + 39.3 s and RATIR from T + 121.4 s. We supplement the optical data with the X-ray light curve from Swift/XRT. We observe an optical flare from T + 110 s to T + 550 s, with a temporal index decay O,decay = 1.32 0.01, and Δt/t = 1.63, which we interpret as the signature of a reverse shock component. After the initial normal decay the light curves show a long plateau from T + 500 s to T + 7800 s in both X-rays and the optical before decaying again after an achromatic jet break at T + 7800 s. Fluctuations are seen during the plateau phase in the optical. Adding to the complexity of GRB afterglows, the plateau phase (typically associated with the coasting phase of the jet) is seen in this object after the "normal" decay phase (associated with the deceleration phase of the jet), and the jet break phase occurs directly after the plateau. We suggest that this sequence of events can be explained by a rapid deceleration of the jet with td 40 s due to the high density of the environment ( 100 cm−3) followed by reactivation of the central engine, which causes the flare and powers the plateau phase.
This work investigates biodiesel production via transesterification of Mexican palm oil with methanol catalyzed by binary solid base core–shell catalysts with improved catalytic stability. A series ...of CaO–ZnO mixed solids were prepared using an inexpensive co–precipitation method by varying ZnO content from 5 to 20 mol%. Several factors, such as surface basicity, ZnO content, phase compositions, and thermal treatment of the catalysts, were all proven to be crucial for the production of biodiesel with good quality. Thermal treatment could effectively remove the surface adsorbed water and impurities and improved the catalytic activity. The addition of ZnO to CaO significantly enhanced the catalysts’ stability; however, it led to lower surface basicity and slightly diminished catalytic activity. ZnO doping inhibited the formation of surface Ca(OH)2 and promoted the formation of Ca–Zn–O or CaZn2(OH)6 phase as the core and a surface CaCO3 shell, which effectively decreased Ca2+ leaching by approximately 74% in methanol and 65% in a methanol–glycerol (4:1) mixture. A combined method of separation and purification for obtaining clean biodiesel with high quality was proposed. The biodiesel obtained under the control conditions exhibited properties which satisfied the corresponding standards well.
We observed the afterglow of GRB 130427A with the Reionization and Transients Infrared Camera (RATIR) instrument on the 1.5 m Harold L. Johnson telescope of the Observatorio Astronómico Nacional in ...Sierra San Pedro Mártir. Our homogenous griZY JH photometry extends from the night of the burst to three years later. We fit a model for the afterglow. There is a significant positive residual that matches the behavior of SN 1998bw in the griZ filters; we suggest that this is a photometric signature of the supernova SN 2013cq associated with the Gamma-ray burst. The peak absolute magnitude of the supernova is M r = − 18.43 0.11 .
The aim of the study was to analyze the association between the superoxide dismutase 2 (SOD2) gene variants rs2758346, rs5746094, and rs2758331 and breast cancer (BC) in the Mexican population as ...well as to perform in silico assessments of the variants' potential impact.
We performed in silico analysis and analyzed 489 healthy women and 467 BC patients using TaqMan assays and Real-Time PCR.
The TT genotype, the T allele of the rs2758346 variant, and the CC genotype of both rs5746094 and rs2758331 were identified as BC risk factors (p < 0.05). The TT and CTTT genotype of the rs2758346 variant stratified by the presence of ki-67 (> 20%), TCCC, and estrogen receptor (ER)-positive of the rs5746094 variant, and the CC and CT genotypes of rs2758331 stratified by menopause status and non-chemotherapy response were risk factors. The TTC and TTA haplotypes are risk factors for BC. In silico analysis revealed that the rs2758346, rs5746094, and rs2758331 variants could influence SOD2 gene regulation by transcription factors and circulating RNAs (circRNAs).
The rs2758346, rs5746094, and rs2758331 variants of the SOD2 gene were associated with BC risk and could influence SOD2 regulation by transcription factors and circRNAs.
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