Can the rapid braking of the white dwarf in AE Aquarii be explained in terms of the gravitational wave emitter mechanism?

The spin-down power of the white dwarf in the close binary AE Aquarii significantly exceeds the bolometric luminosity of the system. The interpretation of this phenomenon in terms of the gravitational-wave emitter mechanism has been recently suggested by Choi & Yi. The basic assumption of their interpretation is that the spatially limited blobs or mounds of the mass \delta m ~ 10^{-3} M_sun, are present at the magnetic poles of the white dwarf. We show that the mounds of this mass can be confined by the magnetic field of the white dwarf only if the dipole magnetic moment of the star exceeds 4x10^{37} G cm^3. Under these conditions, however, the magnetodipole losses of the white dwarf would exceed the evaluated spin-down power 6 orders of magnitude. On this basis we discard a possibility that the observed rapid braking of the white dwarf in AE Aquarii can be explained in terms of the mechanism proposed by Choi & Yi.Comment: 6 pages, published in ApJ, 576, L5

On the accretion luminosity of isolated neutron stars

The accretion process onto a magnetized isolated neutron star, which captures material from the interstellar medium, is discussed. The evolutionary track of such a star can be presented as a sequence of four states: ejector, supersonic propeller, subsonic propeller, and steady accretor. I show that subsonic propeller - accretor transition does not occur as long as the magnetic field of the star is strong enough to control the accretion flow in the stellar vicinity. During the subsonic propeller state the accretion rate onto the stellar surface is limited to the rate of plasma diffusion into its magnetosphere. The diffusion rate is at least three orders of magnitude smaller than the maximum possible mass capture rate by the star. Therefore, the expected accretion luminosity of magnetized isolated neutron stars is at least three orders of magnitude smaller than that previously evaluated.Comment: 4 pages, accepted for publication in A&

Kajian Numerik Korelasi Perpindahan Panas Konveksi Alamiah Aliran Nanofluida Zro2-air pada Anulus Vertikal

KAJIAN NUMERIK KORELASI PERPINDAHAN PANAS KONVEKSI ALAMIAH ALIRAN NANOFLUIDA ZrO2-AIR PADA ANULUS VERTIKAL. Salah satu aspek penting dalam keselamatan reaktor nuklir adalah kemampuan fluida pendingin dalam mengambil panas dari sumber panas. Sejalan dengan hal tersebut telah berkembang banyak pemikiran untuk menggunakan nanofluida sebagai fluida pendingin alternatif menggantikan fluida air guna memaksimalkan pengambilan panas dari sumber panas di dalam teras reaktor. Hasil beberapa penelitian menunjukkan bahwa penggunaan nanofluida pada sistem pendingin reaktor nuklir dapat meningkatkan batas CHF (critical heat flux). Selain itu mengurangi penyerapan neutron, dan meningkatkan konduktivitas panas air pendingin. Belum banyak dilakukan penelitian yang berkaitan dengan karakteristik perpindahan panas nanofluida di dalam reaktor untuk menunjang analisis termohidrolik reaktor berpendingin nanofluida. Berkaitan dengan hal tersebut, pada penelitian ini dilakukan kajian numerik korelasi perpindahan panas aliran nanofluida ZrO2-air pada model berkas bahan bakar reaktor melalui pendekatan aliran fluida pada anulus vertikal, menggunakan metode Computational of Fluid Dynamic (CFD). Hasil penelitian menunjukkan bahwa penggunaan nanofluida ZrO2-air dengan konsentrasi 1% meningkatkan nilai bilangan Nusselt (NU) sekitar 8 - 15% dibandingkan menggunakan fluida dasar (air), dan diperoleh persamaan empirik korelasi perpindahan panas konveksi alamiah aliran nanofluida ZrO2-air pada pipa anulus vertikal sebagai dan

Efek Kebocoran Beamtube Dan Pipa Primer Penukar Panas Pada Suatu Model Reaktor Riset 1 Mw Berbahan Bakar Tipe Silinder

Telah dilakukan analisis transien menggunakan program komputer RELAP5/Mod3.2 terhadap model reaktor riset berbahan bakar tipe silinder daya 1 MW dan diasumsikan mengalami kebocoran pada beamtube, pipa cold leg, dan pipa hot leg. Berdasarkan hasil analisis diketahui reaktor mencapai kestabilan pada daya 1 MW adalah 1650 detik setelah kekritisan. Pada kondisi stabil suhu pusat dan suhu kelongsong bahan bakar pada kanal terpanas, serta suhu air pendingin primer keluar dari kanal terkait berturut-turut adalah 529,35 OC, 98,37 OC, 81,27 OC. Pada 7,3 detik setelah beamtube bocor, atau 5,1 detik setelah pipa cold leg bocor, atau 6,2 detik setelah pipa hot leg bocor reaktor scram karena level air tangki telah turun 0,5 m. Penurunan air tangki ini terhenti pada level 0,959 m ketika 97,7 detik setelah beamtube bocor, atau pada level 1,252 m ketika 76,4 detik setelah pipa cold leg bocor, atau pada level 1,252 m ketika 78,6 detik setelah pipa hot leg bocor. Pada kondisi ini suhu pusat dan suhu kelongsong bahan bakar pada kanal terpanas, serta suhu air pendingin primer keluar dari kanal terkait berturut-turut adalah 96,25 OC, 89,63 OC, 78,96 OC untuk kebocoran beamtube, atau 87,12 OC, 78,31 OC, 69,10 OC untuk kebocoran pipa cold leg, atau 87,32 OC, 78,54 OC, 69,43 OC untuk kebocoran pipa hot leg. Berbeda dengan kebocoran pada pipa cold leg dan pipa hot leg, suhu-suhu tersebut pada kebocoran beamtube cenderung terus naik karena sisa panas peluruhan, dan air tangki yang tersedia tidak mampu mengambil panas tersebut secara maksimal, sehingga diperlukan sistem pendinginan teras darurat (SPTD) untuk mendinginkannya

On a Site of X-ray Emission in AE Aquarii

An analysis of recently reported results of XMM-Newton observations of AE Aqr within a hypothesis that the detected X-ray source is located inside the Roche lobe of the white dwarf is presented. I show this hypothesis to be inconsistent with the currently adopted model of mass-transfer in the system. Possible solutions of this problem are briefly discussed.Comment: 4 pages, accepted for publication in ApJ Letter

Distribusi Foraminifera Bentik di Perairan Aceh

Perairan Aceh termasuk Pulau Weh, Pulau Breuh dan Pulau Penasi merupakan area terluar di sisi barat Kepulauan Indonesia yang menghadap ke Samudera Hindia. Wilayah ini sangat menarik bagi para peneliti terutama setelah kejadian tsunami pada tahun 2004. Tujuan dari penelitian adalah untuk mengetahui distribusi foraminifera sebagai organisme yang sensitif terhadap Perubahan lingkungan. Sebanyak 32 contoh sedimen diambil pada kedalaman 7- 170 meter dan terpilih 11 contoh untuk studi foraminifera. Hasil penelitian menunjukkan bahwa ada 45 spesies foraminifera bentik yang sangat berlimpah, terdiri atas 28 spesies anggota Subordo Rotaliina, Miliolina (7 spesies) dan Textulariina (10 spesies). Amphistegina papilosa dijumpai dalam jumlah sangat berlimpah dan tersebar merata yang memberi indikasi kondisi lingkungan terumbu karang baik. Ammonia tepida sangat dominan (47%) di sebelah utara Pulau Weh (S30) dibandingkan dengan spesies lain. Di bagian Timur Pulau Penasi, ditemukan cangkang foraminifera dalam kondisi rusak dalam jumlah berlimpah yang dapat dikaitkan dengan arus kuat di lokasi ini. Kata kunci : foraminifera bentik, distribusi, perairan Aceh The Aceh waters including Weh, Breuh and Penasi islands are the outer parts of northwestern Indonesia that facing the Indian Ocean. This area is interested for many scientists especially after tsunami in 2004. The purpose of this study is to establish the distribution of benthic foraminifera as a sensitive indicator of environmental changes. Thirty two (32) surface sediment samples were collected at the water depth of 7-170 m and eleven samples were selected for foraminiferal study. The results show 45 species of benthic foraminifera very abundantly and consists of 28 species belong to Suborder Rotaliina, Miliolina (7 species) and Textularia (10 species). Amphistegina papilosa is found abundantly and widely distribution that provide an indication of good reef environments. Ammonia tepida is very dominant(47%) in the northern part of Weh island compared with other species. Abnormal shells of foraminifera were found abundantly in the eastern part of Penasi Island that related to strong current in this area. Keywords: benthic foraminifera, distribution, Aceh water

Knowledge and achievement motivation of marine fishers : A case of alternate livelihood options in Tamilnadu

In recent past, farming of marine fishes is being encouraged among the marine fishers to supplement the household income from capture fisheries, because the fish catch is declining. The study on extent of knowledge and achievement motivation of marine fishers’ adopting alternate livelihood options like sea cage farming, seaweed farming and ornamental fish culture was conducted in Ramanathapuram district of Tamil Nadu since many marine fisheries related activities are being undertaken in larger scale in comparison to other coastal districts. Overall analyses on level of achievement motivation reveal that majority of respondents who are adopting the alternate livelihood options are having medium to high level of achievement motivation. All the farming options have to be undertaken in the sea, which is a common property and it demands a common consensus in a particular village or region for taking up an activity in a desirable and profitable way. Hence, the need for personal achievement was present in majority of fishers, followed by personal achievement oriented influence and need for social achievement. The study found that fishers were able to perform better in the knowledge test since they gained adequate knowledge on all the alternate livelihood options

Penerapan CSR Pada Presepsi Mahasiswa Sebagai Pendukung CSR (CSR SUPPORT) Di Seluruh PTS Di Bandar Lampung

CSR is a social activities been held by the as a form of the responsibility of the company for the society, and environment. CSR refer to all ties what happened between a company with all stakeholders. Students as a community educated, have an important role to play in a community social even them in gave a more objective and intact about how an entity run correctly and without intersects with social norms.Student predicted as a CSR support in giving hope to confidence in a person in support of whether or not certain a CSR in an entity. Alignment between hope students as a supporter of csr with the activities of CSR who was executed by the company would affect CSR company activities. Dimensions law, economic and ethical be hopeless area for a supporter of csr that the company being able to support development of the dimensions so that it becomes independent variable while support csr become the dependent variable for in this research. A method of this research use the model equation structural ( structural equation unified / SEM ) by using path analysis with smart software pls 2.0 .M3

E‐Book Tune‐Up: Maintaining, Sustaining, and Expanding Your Demand‐Driven E‐Book Program

Just like a car, an e‐book program needs continuous maintenance in order to run smoothly. What can we do to structure our e‐book collections to better meet institutional need? Many factors come into play in building a successful demand‐driven acquisition (DDA) program. Student preferences, actual use, collection development, and faculty/staff education and support are all important aspects of maintaining and sustaining a DDA program. This paper describes how the Furman University Library in South Carolina and the Metropolitan State University Library (Metro State) in Minnesota assessed and fine‐tuned their respective DDA programs, and the results of these changes

Evaluation of fatty acid profile with special reference to hypertension intake from marine edible fishes

The present study describes the changes in fatty acid profile in hypertension patients by up taking the marine edible fishes Elutherenema tetradactylum, Sphyraena obtusata and Siganus javus because these marine edible fishes are rich in ? –fatty acids.  In this study the total cholesterol, HDL and LDL were significantly decreased from 211.9 – 202.1 mg/dl, 177-159.6 mg/dl. The palmitic acid (C16:0) was found significantly higher in all of peoples compared with other SFAs. This study revealed that the most abundant in individual FAs 16:0,18:0,18:1 n9 and 20:2 n6 were present in blood in both before and after dietary intake. The minimal changes of SFAs levels were decreased averagely from 59.2 to 52.2%. In addition to above PUFAs also increased from 27.7-30.5%. The essential FAs like ALA (C18:3n3), EPA (C20:5n3) and DHA (C22:6n3) were accounting in the range of 2.64-2.92%, 3.67-3.94% and 3.65-4.38%. Omega – 6/3 ratio were recorded from 1.77-2.45%. This study proves the marine edible fishes reduce the hypertension of the patients. Keywords: Edible fishes, ? –fatty acids, SFAs, HDL and LD