This paper introduces a new analytical approach for the calculation of Quasi Normal Modes (QNMs) of black holes. The proposed method employs the Rosen-Morse function, in order to find the ...approximated quasi-normal frequencies of Schwarzschild black hole. The presented method, compared with the previous related method, demonstrates to be a more precise approximation. The corrected modes based on this research, are claimed to be a generalized form of QNMs found by Pösch-Teller function. The numerical results of the new approach are calculated and compared with the results obtained by Mashhoon method and numerical method.
In the present study, recovery of lithium as lithium aluminate from Urmia Lake was investigated. A coprecipitation method was utilized by using an aluminum salt
AlCl
3
.
6
H
2
O
. Lithium ions are ...adsorbed on aluminum hydroxide, which is prepared by adding
NaOH
and
AlCl
3
.
6
H
2
O
to the brines at
Al
3
+
Li
+
molar ratio ≈5. The results showed that the maximum
Li
+
ion adsorption was adsorbed at pH ~ 7. Also, by increasing the temperature from 30 °C to 40 °C, lithium ions adsorption was decreased. The maximum adsorption amount of
Al
OH
3
was at 30 °C, pH = 7 and density 1.31. The obtained results from adsorption of
Li
+
of Urmia Lake were compared with four isotherm models, Langmuir, Dubinin–Radushkevich, Freundlich and Temkin isotherms. In addition, sulfuric acid was used for
Li
+
desorption from aluminum hydroxide.
In this research, we find the quantum correction of the Schwarzschild black hole metric based on the generalized uncertainty principle (GUP). We assume a massless field scalar field, with an ...effective potential according to the GUP effect. After obtaining the effective potential numerically, we apply approximation on the effective potential to find the phase shift of the scattered wave function. Moreover, the GUP corrected reflection and transmission coefficient of scattered radial wave function are calculated with the Pösch-Teller method.
In this work, by a novel approach to studying the scattering of a Schwarzschild black hole, the non-commutativity is introduced as perturbation. We begin by reformulating the Klein–Gordon equation ...for the scalar field in a new form that takes into account the deformed non-commutative spacetime. Using this formulation, an effective potential for the scattering process is derived. To calculate the quasinormal modes, we employ the WKB method and also utilize fitting techniques to investigate the impact of non-commutativity on the scalar quasinormal modes. We thoroughly analyze the results obtained from these different methods. Moreover, the greybody factor and absorption cross section are investigated. Additionally, we explore the behavior of null geodesics in the presence of non-commutativity. Specifically, we examine the photonic, and shadow radius as well as the light trajectories for different non-commutative parameters. Therefore, by addressing these various aspects, we aim to provide a comprehensive understanding of the influence of non-commutativity on the scattering of a Schwarzschild-like black hole and its implications for the behavior of scalar fields and light trajectories.
Abstract
We study the spherical collapse model in the framework of spatially flat power law f(T) ∝ (− T)
b
gravity model. We find that the linear and non-linear growth of spherical overdensities of ...this particular f(T) model are affected by the power-law parameter b. Finally, we compute the predicted number counts of virialized haloes in order to distinguish the current f(T) model from the expectations of the concordance Λ cosmology. Specifically, the present analysis suggests that the f(T) gravity model with positive (negative) b predicts more (less) virialized objects with respect to those of Λ cold dark matter.
We present the discovery of two small planets transiting HD 93963A (TOI-1797), a GOV star (
M
*
= 1.109 ± 0.043
M
⊙
,
R
*
= 1.043 ± 0.009
R
⊙
) in a visual binary system. We combined TESS and CHEOPS ...space-borne photometry with MuSCAT 2 ground-based photometry, ‘Alopeke and PHARO high-resolution imaging, TRES and FIES reconnaissance spectroscopy, and SOPHIE radial velocity measurements. We validated and spectroscopically confirmed the outer transiting planet HD 93963 A c, a sub-Neptune with an orbital period of
P
c
≈ 3.65 d that was reported to be a TESS object of interest (TOI) shortly after the release of Sector 22 data. HD 93963 A c has amass of
M
c
= 19.2 ± 4.1
M
⊕
and a radius of
R
c
= 3.228 ± 0.059
R
⊕
, implying a mean density of
ρ
c
= 3.1 ± 0.7 g cm
-3
. The inner object, HD 93963 A b, is a validated 1.04 d ultra-short period (USP) transiting super-Earth that we discovered in the TESS light curve and that was not listed as a TOI, owing to the low significance of its signal (TESS signal-to-noise ratio ≈6.7, TESS + CHEOPS combined transit depth
D
b
= 141.5
−8.3
+8.5
ppm). We intensively monitored the star with CHEOPS by performing nine transit observations to confirm the presence of the inner planet and validate the system. HD 93963 A b is the first small (
R
b
= 1.35 ± 0.042
R
⊕
) USP planet discovered and validated by TESS and CHEOPS. Unlike planet c, HD 93963 Ab is not significantly detected in our radial velocities (
M
b
= 7.8 ± 3.2
M
⊕
). The two planets are on either side of the radius valley, implying that they could have undergone completely different evolution processes. We also discovered a linear trend in our Doppler measurements, suggesting the possible presence of a long-period outer planet. With a
V
-band magnitude of 9.2, HD 93963 A is among the brightest stars known to host a USP planet, making it one of the most favourable targets for precise mass measurement via Doppler spectroscopy and an important laboratory to test formation, evolution, and migration models of planetary systems hosting ultra-short period planets.
High-precision spectrographs can on occasion exhibit temporal variations in their reference velocity or nightly zero point (NZP). One way to monitor the NZP is to measure bright stars, whose ...intrinsic radial velocity variation is assumed to be much smaller than the instrument precision. The variations of these bright stars, which is primarily assumed to be instrumental, are then smoothed into a reference radial velocity time series (master constant) that is subtracted from the observed targets. While this method is effective in most cases, it does not fully propagate the uncertainty arising from NZP variations. We present a new method for correcting for NZP variations in radial velocity time series. This method uses Gaussian processes based on ancillary information to model these systematic effects. Moreover, it enables us to propagate the uncertainties of this correction into the overall error budget. Another advantage of this approach is that it relies on ancillary data that are collected simultaneously with the spectra and does not solely depend on dedicated observations of constant stars. We applied this method to the SOPHIE spectrograph at the Haute-Provence Observatory using a few instrument housekeeping data, such as the internal pressure and temperature variations. Our results demonstrate that this method effectively models the red noise of constant stars, even with a limited number of housekeeping data, while preserving the signals of exoplanets. Using simulations with mock planets and real data, we found that this method significantly improves the false-alarm probability of detections. It improves the probability by several orders of magnitude. Additionally, by simulating numerous planetary signals, we were able to detect up to 10% more planets with small-amplitude radial velocity signals. We used this new correction to reanalyse the planetary system around HD158259 and to improve the detection of the outermost planets. We propose this technique as a complementary approach to the classical master-constant correction of the instrumental red noise. We also suggest to decrease the observing cadence of the constant stars to optimise the telescope time for scientific targets.
Aims The management of a significant bony defect following excision of a diaphyseal atrophic femoral nonunion remains a challenge. We present the outcomes using a combined technique of acute femoral ...shortening, stabilized with a long retrograde intramedullary nail, accompanied by bifocal osteotomy compression and distraction osteogenesis with a temporary monolateral fixator. Patients and Methods Eight men and two women underwent the 'rail and nail' technique between 2008 and 2016. Proximal locking of the nail and removal of the external fixator was undertaken once the length of the femur had been restored and prior to full consolidation of the regenerate. Results The mean lengthening was 7 cm (3 to 11). The external fixator was removed at a mean of 127 days (57 to 220). The mean bone healing index was 28 days/cm and the mean external fixation index was 20 days/cm (11 to 18). There were no superficial or deep infections. Conclusion This small retrospective study shows encouraging results for a combined technique, enabling compression of the femoral osteotomy, alignment, and controlled lengthening. Removal of the fixator and proximal locking of the nail reduces the risk of complications and stabilizes the femur with the maximum working length of the nail. Cite this article: Bone Joint J 2018;100-B:634-9.
Activation of p53 by cellular stress may lead to either cell cycle arrest or apoptotic cell death. Restrictions in a cell's ability to halt the cell cycle might, in turn, cause mitotic catastrophe, a ...delayed type of cell death with distinct morphological features. Here, we have investigated the contribution of p53 and caspase-2 to apoptotic cell death and mitotic catastrophe in cisplatin-treated ovarian carcinoma cell lines. We report that both functional p53 and caspase-2 were required for the apoptotic response, which was preceded by translocation of nuclear caspase-2 to the cytoplasm. In the absence of functional p53, cisplatin treatment resulted in caspase-2-independent mitotic catastrophe followed by necrosis. In these cells, apoptotic functions could be restored by transient expression of wt p53. Hence, p53 appeared to act as a switch between apoptosis and mitotic catastrophe followed by necrosis-like lysis in this experimental model. Further, we show that inhibition of Chk2, and/or 14-3-3sigma deficiency, sensitized cells to undergo mitotic catastrophe upon treatment with DNA-damaging agents. However, apoptotic cell death seemed to be the final outcome of this process. Thus, we hypothesize that the final mode of cell death triggered by DNA damage in ovarian carcinoma cells is determined by the profile of proteins involved in the regulation of the cell cycle, such as p53- and Chk2-related proteins.
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