The quest for blue supergiants: binary merger models for the evolution of the progenitor of SN 1987A

We present the results of a detailed, systematic stellar evolution study of binary mergers for blue supergiant (BSG) progenitors of Type II supernovae. In particular, these are the first evolutionary models that can simultaneously reproduce nearly all observational aspects of the progenitor of SN 1987A, \text{Sk}-69\,^{\circ}202, such as its position in the HR diagram, the enrichment of helium and nitrogen in the triple-ring nebula, and its lifetime before its explosion. The merger model, based on the one proposed by Podsiadlowski 1992 et al. and Podsiadlowski 2007 et al., consists of a main sequence secondary star that dissolves completely in the common envelope of the primary red supergiant at the end of their merger. We empirically explore a large initial parameter space, such as primary masses ($15\,\text{M}_{\odot}$, $16\,\text{M}_{\odot}$, and $17\,\text{M}_{\odot}$), secondary masses ($2\,\text{M}_{\odot}$, $3\,\text{M}_{\odot}$, ..., $8\,\text{M}_{\odot}$) and different depths up to which the secondary penetrates the He core of the primary during the merger. The evolution of the merged star is continued until just before iron-core collapse and the surface properties of the 84 pre-supernova models ($16\,\text{M}_{\odot}-23\,\mathrm{M}_{\odot}$) computed have been made available in this work. Within the parameter space studied, the majority of the pre-supernova models are compact, hot BSGs with effective temperature $>12\,\text{kK}$ and radii of $30\,\text{R}_{\odot}-70\,\mathrm{R}_{\odot}$ of which six match nearly all the observational properties of \text{Sk}-69\,^{\circ}202.Comment: Submitted to MNRAS. 21 pages, 11 figures, 7 table

New modification of the hestenes-stiefel with strong wolfe line search

. The method of the nonlinear conjugate gradient is widely used in solving large-scale unconstrained optimization since been proven in solving optimization problems without using large memory storage. In this paper, we proposed a new modification of the Hestenes-Stiefel conjugate gradient parameter that fulfils the condition of sufficient descent using a strong Wolfe-Powell line search. Besides, the conjugate gradient method with the proposed conjugate gradient also guarantees low computation of iteration and CPU time by comparing with other classical conjugate gradient parameters. Numerical results have shown that the conjugate gradient method with the proposed conjugate gradient parameter performed better than the conjugate gradient method with other classical conjugate gradient parameters

The Popular Tale : A Study on Retention and Deconstruction of Collective Memory in Duffer Brothers\u27 Stranger Things and Bisha Ali\u27s Miss Marvel

In On Media Memory; Collective Memory in New Media Age, cultural memory is described as “a version of past, defined and negotiated through changing socio-political power circumstances and agendas" (qtd. in Bosh TE 3). The popular entertainment of every age is obliged to incorporate elements of cultural memory in it to remain popular. The paper seeks to interrogate the role played by the integration of cultural memory in the popular American science fiction web series, Stranger Things, and the latest production of Marvel Cinematic Universe, Miss Marvel. The Stranger Things series, written and directed by the Duffer brothers is set in the mid-1980s. The age is recreated through certain elements that constitute cultural memory. They are placed within the context of the Ukraine crisis which urgently necessitates anti-Russian narratives in American popular entertainment. Miss Marvel appeared as a fresh wind in MCU, questioning the collective mistrust towards the Pakistani Muslim community and addressing the scars of partition as well as migration in third-generation Pakistani-Americans. The two web series featured on Netflix and Disney Hotstar are compared and contrasted to elucidate how popular entertainment can act as a soft power for the retention and deconstruction of cultural memory

Study on safety performance factors and sustainability in pipeline sleeper construction

Construction industry is an important growth indicator because it generates investment opportunities across multiple related sectors. The construction task or work environment is very risky and hazardous and its susceptibility to accident. The major cause of the accident is the employees' poor safety performance in construction sites. These root causes of accidents and factors influencing them need to be studied in order to improve safety results. In pipeline sleeper construction, safety is a dynamic decision issue close to normal construction cases. The study identifies the critical risk factors affecting the safety performance and ways to achieve sustainability in pipeline sleeper construction to counteract the risk of accident occurrence. Based on the evaluation of the questionnaire survey, the study explains twelve most important factors and sub factors, which were rated to have more than a moderate effect on safety performance. The six keys to sustainable success for integrating worker protection in the assessment of sustainable construction is also discussed. Keywords-Hazards, pipeline sleeper, safety performance, ris

GAMBARAN FUNGSI KOGNITIF PADA PASIEN DENGAN KADAR FERITIN SERUM RENDAH DI RUMAH SAKIT UMUM DAERAH DR. ZAINOEL ABIDIN BANDA ACEH

Pemeriksaan yang paling sensitif untuk menilai defisiensi besi adalah feritin serum. Kadar feritin serum yang rendah menggambarkan penurunan cadangan besi tubuh. Kadar feritin serum yang rendah berhubungan dengan menurunnya proses metabolik yang mempengaruhi fungsi otak sehingga dapat menyebabkan gangguan fungsi kognitif. Penelitian ini bertujuan untuk mengetahui gambaran fungsi kognitif pada pasien dengan kadar feritin serum rendah di Rumah Sakit Umum Daerah dr. Zainoel Abidin Banda Aceh. Jenis penelitian ini adalah deskriptif dengan rancangan cross sectional. Pengambilan sampel dari tanggal 19 Oktober sampai dengan 11 Desember 2017. Subjek penelitian dikumpulkan dengan metode accidental sampling. Kadar feritin serum didapatkan dari hasil pemeriksaan laboratorium dan fungsi kognitif dinilai menggunakan kuisioner Montreal Cognitive Assesment versi Indonesia (MoCA-Ina). Hasil penelitian didapatkan 30 subjek penelitian yang memenuhi kriteria inklusi. Berdasarkan penelitian ini didapatkan kasus kadar feritin rendah paling banyak pada usia ?56 tahun (30%), jenis kelamin wanita (60%), tingkat pendidikan terakhir tamat SMA (40%), dan IRT (26,6%). Kadar feritin paling banyak yaitu feritin serum sangat rendah ?12 ng/mL (86,67%). Pasien dengan kadar feritin rendah yang memiliki fungsi kognitif normal 13,34% sedangkan yang mengalami gangguan fungsi kognitif 86,66%. Gangguan kognitif pada pasien dengan kadar feritin serum rendah bertambah seiring dengan kadar feritin sangat rendah ?12 ng/mL (88,5%), bertambahnya usia (85,5%), jenis kelamin pria (91,7%), dan tingkat pendidikan yang lebih rendah (66,7%).Kata kunci: Kadar feritin serum rendah, fungsi kognitif, MoCA-In

The Effect Of Voltage To Welded Aluminum And Steel By Using Gas Metal Arc Welding (GMAW)

The purpose of this research is to assess the possibility of joining two different materials (aluminum and steel) by using one of the thermal joining that is gas metal arc welding (GMAW) which can be used in the industries such as in aviation and automotive. The joints will be obtained by GMAW process in which melts metal by heat supplying an electric arc established between a continuously fed filler wire electrode. Test will be conducted with constant welding parameter but with the different voltage. The results will be analyzed by means of hardness test, impact test, ultimate tensile test and microstructure at the welded joint. The strength of the joints varied with increasing of voltage when welding process is implied. The results will be proved after the tests are being done whether the technique of joining aluminum and steel by using GMAW is applicable