Effect of 12C+^{12}C+ 12C^{12}C Reaction & Convective Mixing on the Progenitor Mass of ONe White Dwarfs

Stars in the mass range ~8 - 12 $M_{\odot }$ are the most numerous massive stars. This mass range is critical because it may lead to supernova (SN) explosion, so it is important for the production of heavy elements and the chemical evolution of the galaxy. We investigate the critical transition mass ($M_{up}$), which is the minimum initial stellar mass that attains the conditions for hydrostatic carbon burning. Stars of masses < $M_{up}$ evolve to the Asymptotic Giant Branch and then develop CO White Dwarfs, while stars of masses $\geqslant$ $M_{up}$ ignite carbon in a partially degenerate CO core and form electron degenerate ONe cores. These stars evolve to the Super AGB (SAGB) phase and either become progenitors of ONe White Dwarfs or eventually explode as electron-capture SN (EC-SN). We study the sensitivity of $M_{up}$ to the C-burning reaction rate and to the treatment of convective mixing. In particular, we show the effect of a recent determination of the $^{12}C+$ $^{12}C$ fusion rate, as well as the extension of the convective core during hydrogen and helium burning on $M_{up}$ in solar metallicity stars. We choose the 9$M_{\odot }$ model to show the detailed characteristics of the evolution with the new C-burning rate.Comment: Submitted to AIP Conference proceedings of Carpathian Summer School of Physics-201

Synthesis of C-rich dust in CO nova ourbursts

Context. Classical novae are thermonuclear explosions that take place in the envelopes of accreting white dwarfs in stellar binary systems. The material transferred onto the white dwarf piles up under degenerate conditions, driving a thermonuclear runaway. In those outbursts, about 10-7 - 10-3 Msun, enriched in CNO and, sometimes, other intermediate-mass elements (e.g., Ne, Na, Mg, or Al, for ONe novae) are ejected into the interstellar medium. The large concentrations of metals spectroscopically inferred in the nova ejecta reveal that the (solar-like) material transferred from the secondary mixes with the outermost layers of the underlying white dwarf. Aims. Most theoretical models of nova outbursts reported to date yield, on average, outflows characterized by O > C, from which only oxidized condensates (e.g, O-rich grains) would be expected, in principle. Methods. To specifically address whether CO novae can actually produce C-rich dust, six different hydrodynamic nova models have been evolved, from accretion to the expansion and ejection stages, with different choices for the composition of the substrate with which the solar-like accreted material mixes. Updated chemical profiles inside the H-exhausted core have been used, based on stellar evolution calculations for a progenitor of 8 Msun through H and He-burning phases. Results. We show that these profiles lead to C-rich ejecta after the nova outburst. This extends the possible contribution of novae to the inventory of presolar grains identified in meteorites, particularly in a number of carbonaceous phases (i.e., nanodiamonds, silicon carbides and graphites).Comment: 5 pages, accepted for publication in Astronomy & Astrophysic

Primary lens extraction for glaucoma management: A review article

AbstractRecently, primary lens extraction alone gained more acceptance as an alternative surgical approach for glaucoma management. This view was supported by the advances in phacoemulsification and intraocular lenses with greater safety and visual recovery, in addition to a substantial reduction of intraocular pressure and deepening of the anterior chamber and filtration angle. The decrease in IOP after cataract surgery in primary open-angle glaucoma (POAG) is mild, less predictable, related to baseline levels, and may return to presurgical values after an initial period of reduction. Therefore, the IOP-lowering effect of primary cataract extraction in POAG may be insufficient to achieve adequate IOP control. The IOP reduction after lens extraction is consistently greater in eyes with primary angle closure glaucoma (PACG) than in eyes with POAG. Primary lens extraction in acute PACG eliminates, or at least, reduces the risk of recurrence of acute attacks and deepens the anterior chamber and widens the angle which reduces the risk of progression of peripheral anterior synechiae and development of chronic PACG. Primary lens extraction may be more preferable to glaucoma incisional surgery in mild to moderate PACG eyes with appositional angle closure. The decision to do lens extraction as a primary treatment for glaucoma should be individualized based upon several factors other than the effect on IOP. These factors include patients’ characteristics, surgeons’ skills and preferences, status of glaucoma control, type of cataract and intraocular lens implanted, and potential harm of laser treatment for late capsular opacification and fibrosis

The collapse of the Cypress Viaduct during the Loma Prieta earthquake of October 17, 1989

The Loma Prieta earthquake of October 17, 1989 in California was one of the most disastrous earthquakes in U.S history. It caused damage to commercial, residential, and industrial structures, transportation and utilities. This study includes investigations about the Cypress Viaduct collapse re?ported by: California Governor\u27s Board of Inquiry [4].National Institute of Standards and Technology (NEL) W.3The Author. Investigators in the first report concluded that the collapse was due to horizontal ground motion. In the second one, it was due to the vertical ground motion. In the author\u27s investigation, a detailed static and dynamic analyses are performed to determine the cause of the failure. Static analyses are performed to determine the moment and shear capacities of the critical sections. Also to predict the mode and sequence of failure. Dynamic analyses are performed employing the finite element software ADINA to investigate the effect of ground motion on the Viaduct

Financial Leverage and its Impact on Share Value in Commercial banks "Citigroup Bank as a Model for the Period 2000-2022"

Background: The financial leverage, which is called financing by indebtedness or financing by borrowing, which is done by borrowing or issuing indebtedness instruments such as bonds and other financial instruments, is complementary to financing by ownership, which consists of shareholders’ funds and the issuance of shares, so that the financial structure in companies consists of “ownership and indebtedness.” Materials and Methods: The bank's financial leverage was measured through the use of a number of financial ratios, including total liabilities to total assets and total liabilities to total equity, and its impact on the value of the share was measured by using the SPSS program. Conclusions: The results showed that there is a positive correlation between the financial leverage ratios and the value of the share. The value of the share was affected by the mortgage crisis of 2007-2008 AD, as it began to decline in 2007 AD from $359.60 to$29.79 in 2009 AD. From research and study, we find, in addition to the effect of financial leverage, the existence of More than one effect on the stock value

3 Tesla MRI surface coil: Is it sensitive for prostatic imaging??

Objective: This study aimed to check the sensitivity of phased array surface coli of 3T MRI, in pre-sampling diagnosis of prostate cancer, in an attempt to use it instead of endorectal coil.Patients and methods: This was a prospective comparative study, included 20 male patients, presented with suspected prostate cancer due to unexplained high PSA. The study protocol was approved by the ethics committee in Al-Mana General Hospital.Results: Prostate cancer was correctly diagnosed by T2w sequence within 9 patients, 10 by DW&amp;T2w, 13 by T2w – DW-DCE and 14 by of T2w-DW-DCE-MRS sequences.Conclusion: 3T MRI imaging using phased array surface coil is a useful diagnostic tool for detecting prostate cancer, trustworthy when compared to endorectal approach