Hawking radiation as tunneling from a Vaidya black hole in noncommutative gravity

In the context of a noncommutative model of coordinate coherent states, we present a Schwarzschild-like metric for a Vaidya solution instead of the standard Eddington-Finkelstein metric. This leads to the appearance of an exact $(t - r)$ dependent case of the metric. We analyze the resulting metric in three possible causal structures. In this setup, we find a zero remnant mass in the long-time limit, i.e. an instable black hole remnant. We also study the tunneling process across the quantum horizon of such a Vaidya black hole. The tunneling probability including the time-dependent part is obtained by using the tunneling method proposed by Parikh and Wilczek in terms of the noncommutative parameter $\sigma$. After that, we calculate the entropy associated to this noncommutative black hole solution. However the corrections are fundamentally trifling; one could respect this as a consequence of quantum inspection at the level of semiclassical quantum gravity.Comment: 19 pages, 5 figure

Mutation analysis of BRCA1 and BRCA2 genes in Iranian high risk breast cancer families

Background: Telomerase is a ribonucleoprotein enzyme that synthesises telomeres after cell division and maintains chromosomal stability leading to cellular immortalization. Telomerase has been associated with negative prognostic indicators in some studies. The present study aims to detect any association between telomerase sub-units: hTERT and hTR and the prognostic indicators including tumour's size and grade, nodal status and patient's age. Methods: Tumour samples from 46 patients with primary invasive breast cancer and 3 patients with benign tumours were collected. RT-PCR analysis was used for the detection of hTR, hTERT, and PGM1 (as a housekeeping) genes expression. Results: The expression of hTR and hTERT was found in 31(67.4%) and 38 (82.6%) samples respectively. We observed a significant association between hTR gene expression and younger age at diagnosis (p = 0.019) when comparing patients ≤ 40 years with those who are older than 40 years. None of the benign tumours expressed hTR gene. However, the expression of hTERT gene was revealed in 2 samples. No significant association between hTR and hTERT expression and tumour's grade, stage and nodal status was seen. Conclusion: The expression of hTR and hTERT seems to be independent of tumour's stage. hTR expression probably plays a greater role in mammary tumourogenesis in younger women (≤ 40 years) and this may have therapeutic implications in the context of hTR targeting strategies

Black Hole Evaporation in a Noncommutative Charged Vaidya Model

The aim of this paper is to study the black hole evaporation and Hawking radiation for a noncommutative charged Vaidya black hole. For this purpose, we determine spherically symmetric charged Vaidya model and then formulate a noncommutative Reissner-Nordstr$\ddot{o}$m-like solution of this model which leads to an exact $(t-r)$ dependent metric. The behavior of temporal component of this metric and the corresponding Hawking temperature is investigated. The results are shown in the form of graphs. Further, we examine the tunneling process of the charged massive particles through the quantum horizon. It is found that the tunneling amplitude is modified due to noncommutativity. Also, it turns out that black hole evaporates completely in the limits of large time and horizon radius. The effect of charge is to reduce the temperature from maximum value to zero. It is mentioned here that the final stage of black hole evaporation turns out to be a naked singularity.Comment: 25 pages, 36 figures, accepted for publication in J. Exp. Theor. Phy

The Swift-UVOT ultraviolet and visible grism calibration

We present the calibration of the Swift UVOT grisms, of which there are two, providing low-resolution field spectroscopy in the ultraviolet and optical bands respectively. The UV grism covers the range 1700-5000 Angstrom with a spectral resolution of 75 at 2600 Angstrom for source magnitudes of u=10-16 mag, while the visible grism covers the range 2850-6600 Angstrom with a spectral resolution of 100 at 4000 Angstrom for source magnitudes of b=12-17 mag. This calibration extends over all detector positions, for all modes used during operations. The wavelength accuracy (1-sigma) is 9 Angstrom in the UV grism clocked mode, 17 Angstrom in the UV grism nominal mode and 22 Angstrom in the visible grism. The range below 2740 Angstrom in the UV grism and 5200 Angstrom in the visible grism never suffers from overlapping by higher spectral orders. The flux calibration of the grisms includes a correction we developed for coincidence loss in the detector. The error in the coincidence loss correction is less than 20%. The position of the spectrum on the detector only affects the effective area (sensitivity) by a few percent in the nominal modes, but varies substantially in the clocked modes. The error in the effective area is from 9% in the UV grism clocked mode to 15% in the visible grism clocked mode .Comment: 27 pages, 31 figures; MNRAS accepted 23 February 201

Noncommutative Inspired Reissner-Nordstr\"om Black Holes in Large Extra Dimensions

Recently, a new noncommutative geometry inspired solution of the coupled Einstein-Maxwell field equations including black holes in 4-dimension is found. In this paper, we generalize some aspects of this model to the Reissner-Nordstr\"om (RN) like geometries with large extra dimensions. We discuss Hawking radiation process based on noncommutative inspired solutions. In this framework, existence of black hole remnant and possibility of its detection in LHC are investigated.Comment: 24 pages, 12 figures, revised version to appear in Commun. Theor. Phy

Performance of microstrip patch antenna on a reinforced carbon fiber composite ground plane

Using mass-produced multiwall carbon nanotubes (MWCNTs) from different providers, we have fabricated nanocomposites with high and nearly constant shielding effectiveness (SE) over a wide frequency range up to 26.5 GHz. The MWCNT weight fraction and sample thickness were lower than 10% and 2 mm, respectively. The fabrication process and percolation curves are described. A high dc conductivity of 239.1 S/m was achieved at an MWCNT loading of only 8% by weight. The effect of aspect ratio on shielding performance is addressed. By comparing the measured SE of the composite with predictions from a model of the measurement setup using Microwave Studio, the effective conductivity of the nanocomposite was determined. Since the thickness is very important for shielding analysis, the SE/unit thickness diagram was calculated by using the effective parameters of samples. The results were verified experimentally by measuring the SE of samples with different thicknesses

Multiwall Carbon Nanotube-Epoxy Composites With High Shielding Effectiveness for Aeronautic Applications

Using mass-produced multiwall carbon nanotubes (MWCNTs) from different providers, we have fabricated nanocomposites with high and nearly constant shielding effectiveness (SE) over a wide frequency range up to 26.5 GHz. The MWCNT weight fraction and sample thickness were lower than 10% and 2 mm, respectively. The fabrication process and percolation curves are described. A high dc conductivity of 239.1 S/m was achieved at an MWCNT loading of only 8% by weight. The effect of aspect ratio on shielding performance is addressed. By comparing the measured SE of the composite with predictions from a model of the measurement setup using Microwave Studio, the effective conductivity of the nanocomposite was determined. Since the thickness is very important for shielding analysis, the SE/unit thickness diagram was calculated by using the effective parameters of samples. The results were verified experimentally by measuring the SE of samples with different thicknesses

Carbon Nanotube Composites for Wideband Millimeter-Wave Antenna Applications

In this paper, we explore using carbon nanotube (CNT) composite material for wideband millimeter-wave antenna applications. An accurate electromagnetic model of the composite antenna is developed using Microwave Studio for numerical analysis. Good agreement between computed and measured results is shown for both copper and CNT antennas, and their performance is compared. The CNT antenna shows stable gain and radiation patterns over the 24 to 34 GHz frequency range. The dispersion characteristics of the CNT antenna show its suitability for wideband communication systems. Using a quarter-wave matched T-junction as feed network, a two-element CNT antenna array is realized and the performance is compared with a copper antenna. The housing effect on the performance of the CNT antenna is shown to be much lower than for the copper antenna

Accretion, ejection and reprocessing in supermassive black holes

This is a White Paper in support of the mission concept of the Large Observatory for X-ray Timing (LOFT), proposed as a medium-sized ESA mission. We discuss the potential of LOFT for the study of active galactic nuclei. For a summary, we refer to the paper.Comment: White Paper in Support of the Mission Concept of the Large Observatory for X-ray Timin

Multi-wavelength observations of the obscuring wind in the radio-quiet quasar MR 2251-178

Obscuring winds driven away from active supermassive black holes are rarely seen due to their transient nature. They have been observed with multi-wavelength observations in a few Seyfert 1 galaxies and one broad absorption line radio-quiet quasar so far. An X-ray obscuration event in MR 2251-178 was caught in late 2020, which triggered multi-wavelength (NIR to X-ray) observations targeting this radio-quiet quasar. In the X-ray band, the obscurer leads to a flux drop in the soft X-ray band from late 2020 to early 2021. X-ray obscuration events might have a quasi-period of two decades considering earlier events in 1980 and 1996. In the UV band, a forest of weak blueshifted absorption features emerged in the blue wing of Ly$\alpha$ $\lambda1216$ in late 2020. Our XMM-Newton, NuSTAR, and HST/COS observations are obtained simultaneously, hence, the transient X-ray obscuration event is expected to account for the UV outflow, although they are not necessarily caused by the same part of the wind. Both blueshifted and redshifted absorption features were found for He {\sc i} $\lambda10830$, but no previous NIR spectra are available for comparison. The X-ray observational features of MR 2251-178 shared similarities with some other type 1 AGNs with obscuring wind. However, observational features in the UV to NIR bands are distinctly different from those seen in other AGN with obscuring winds. A general understanding of the observational variety and the nature of obscuring wind is still lacking.Comment: ApJ accepte