Finding Young Stellar Populations in Elliptical Galaxies from Independent Components of Optical Spectra

Elliptical galaxies are believed to consist of a single population of old stars formed together at an early epoch in the Universe, yet recent analyses of galaxy spectra seem to indicate the presence of significant younger populations of stars in them. The detailed physical modelling of such populations is computationally expensive, inhibiting the detailed analysis of the several million galaxy spectra becoming available over the next few years. Here we present a data mining application aimed at decomposing the spectra of elliptical galaxies into several coeval stellar populations, without the use of detailed physical models. This is achieved by performing a linear independent basis transformation that essentially decouples the initial problem of joint processing of a set of correlated spectral measurements into that of the independent processing of a small set of prototypical spectra. Two methods are investigated: (1) A fast projection approach is derived by exploiting the correlation structure of neighboring wavelength bins within the spectral data. (2) A factorisation method that takes advantage of the positivity of the spectra is also investigated. The preliminary results show that typical features observed in stellar population spectra of different evolutionary histories can be convincingly disentangled by these methods, despite the absence of input physics. The success of this basis transformation analysis in recovering physically interpretable representations indicates that this technique is a potentially powerful tool for astronomical data mining.Comment: 12 Pages, 7 figures; accepted in SIAM 2005 International Conference on Data Mining, Newport Beach, CA, April 200

Efektivitas Jahe untuk Menurunkan Mual Muntah pada Kehamilan Trimester I di Kelurahan Suka Karya Kecamatan Kota Baru

Sekitar 50% wanita hamil mengalami mual-mual dan sampai muntah-muntah. Hal ini teradi 12 minggu pertama kehamilan, biasanya menghilang pada akhir waktu tersebut, tapi kadang muncul menjelang akhir kehamilan. Tujuan penelitian ini adalah untuk membandingkan frekuensi mual muntah sebelum dan sesudah diberikan jahe pada ibu hamil trimester I. Penelitian ini bersifat analitik dan tekhnik pengambilan sampel menggunakan Accidental Sampling dengan jumlah responden yang di dapat sebanyak 4 orang ibu hamil trimester I yang mengalami mual-muntah. Hasil penelitian diperoleh kehamilan trimester 1 sebagian besar yang mengalami mual ringan sebanyak 1 orang dengan frekuensi 1-3 x/hari dan yang mengalami mual-muntah sedang dengan frekuensi 4-7 x/hari sebanyak 3 orang. Berdasarkan hasil Paried Sample T-Test menunujkan nilai yang signifikan P-Value sebesra 0,03. Hal ini berartri P-Value < α (0,05) hal ini menunjukan bahwa jahe efektif untuk menurunkan mual muntah pada kehamilan trimester I.Kesimpulan penelitian yaitu berdasarkan hasil penelitian bahwa jahe efektif untuk menurunkan mual-muntah pada kehamilan trimester I di Kelurahan Suka Karya Kecamatan Kota Baru. Diharapkan bagi ibu agar lebih mengetahui dan memahami frekuensi mual-muntah selama kehamilan

OPTIMALISASI PENERIMAAN INTENSITAS CAHAYA MATAHARI PADA PERMUKAAN PANEL SURYA (SOLAR CELL) MENGGUNAKAN CERMIN

Abstrak Energi surya merupakan salah satu energi yang bias dikonversi menjadi energi listrik dengan menggunakan panel surya (photovoltaic solar). Pada penelitian ini, dirancang panel surya dengan cermin datar sebagai reflektor scanning dengan empat buah reflektor pada empat sisi panel surya. Tujuan yang ingin dicapai dalam penelitian ini yaitu untuk mendapatkan keluaran panel surya yang optimal menggunakan cemin sebagai media reflektornya dan mendapatkan konfigurasi penempatan cermin untuk meningkatkan keluaran arus dan tegangan panel surya. Metode yang digunakan dalam penelitian ini adalah metode eksperimen dengan melakukan percobaan terhadap objek bahan penelitian dengan kemiringan reflektor cermin 30o, 45o, dan 60o. Dengan penambahan reflector cermin pada panel surya menyebabkan peningkatan keluaran panel surya pada pukul 12.00 Wita. Panel tanpa reflektor mengahasilkan Arus 2,1 Ampere, Tegangan 6,52 Volt. Panel reflektor 30o menghasilkan Arus 1,89 Ampere, Tegangan 6,25 Volt, Panel reflektor 45o, Arus 2,33 Ampere, Tegangan 6,15 Volt dan Panel reflektor Arus 3,02 Ampere, dan Tegangan 6,41 Volt.Kata kunci: Energi; fotovoltaik; panel surya; cermin. Abstract Solar energy is one of the energies that can be converted into electrical energy using solar panels (photovoltaic solar). In this study, a solar panel with a flat mirror as a scanning reflector was designed with four reflectors on the four sides of the solar panel. The objectives to be achieved in this study are to obtain optimal solar panel output using the mirror as a reflector medium and obtain a mirror placement configuration to increase the current and voltage output of the solar panels. The method used in this research is an experimental method by conducting experiments on the object of the research material with a mirror reflector tilt of 30o, 45o, and 60o. With the addition of a mirror reflector on the solar panel, it causes an increase in the output of the solar panel at 12.00 GMT+08. The panel without a reflector produces a current of 2.1 Ampere, a voltage of 6.52 volts. The 30o-reflector panel produces a current of 1.89 Amperes, a Voltage of 6.25 Volts, a 450 Reflector Panel, a Current of 2.33 Amperes, a Voltage of 6.15 Volts and a Current 3.02 Amperes of Reflector Panel, and a Voltage of 6.41 Volts. Keywords: Energy; photovoltaic; solar panel; mirro

Young stellar populations in early-type galaxies in the Sloan Digital Sky Survey

We use a purely data-driven rectified factor analysis to identify early-type galaxies with recent star formation in DR4 of the SDSS Spectroscopic Catalogue. We compare the spectra and environment of these galaxies with `normal' early-types, and a sample of independently selected E+A galaxies. We calculate the projected local galaxy surface density (Sigma_5 and Sigma_10) for each galaxy in our sample, and find that the dependence, on projected local density, of the properties of E+As is not significantly different from that of early-types with young stellar populations, dropping off rapidly towards denser environments, and flattening off at densities < 0.1-0.3 Mpc^-2. The dearth of E+A galaxies in dense environments confirms that E+As are most likely the products of galaxy-galaxy merging or interactions, rather than star-forming galaxies whose star formation has been quenched by processes unique to dense environments. We see a tentative peak in the number of E+A galaxies at Sigma_10 \~ 0.1-0.3 Mpc^-2, which may represent the local galaxy density at which the rate of galaxy-galaxy merging or interaction rate peaks. Analysis of the spectra of our early-types with young stellar populations suggests that they have a stellar component dominated by F stars, ~ 1-4 Gyr old, together with a mature, metal-rich population characteristic of `typical' early-types. The young stars represent > 10% of the stellar mass in these galaxies. This, together with the similarity of the environments in which this `E+F' population and the E+A galaxy sample are found, suggests that E+F galaxies used to be E+A galaxies, but have evolved by a further ~ one to a few Gyr. Our factor analysis is sensitive enough to identify this hidden population. (Abridged)Comment: 7 pages, 5 figures, submitted to MNRAS, minor revisio

Membumikan Budaya Sumatera Utara “Batak Juga Punya Batik”

Indonesia culture plagiarism by other country used to be a hot issue caused the culture it self has been a long time left or dissocialized in general public. One of the cultures that almost claimed by other country is Batik, but finally it got UNESCO recognition as Indonesia culture heritage. Program Kreativitas Mahasiswa (PKM) powered by DIKTI is one of a simple way to contribute in development and keeping the cultures of Indonesia, by following this program we are able to empower local potency art of culture and tourism in North Sumatera especially in form of batik, T-Shirt, and other batik product. Beside that, the effort of batik batak product become one of potential business opportunities for students either in doing the lectures or after graduation

The effect of testing procedure on DSC measurements of Gd-Ti-Zr alloy using ZrO2 container

Differential Scanning Calorimetry (DSC) was applied to determine the critical temperatures of phase transformations in the Gd40Ti30Zr30 alloy (wt%). The comparative measurements were carried out using three types of measuring devices at a temperature RT- 1650°C in the same flowing gas (Ar, 99.9992%) but applying different testing procedures, which allowed obtaining dissimilar oxygen contents in the surrounding atmosphere. The high temperature interaction and reactivity taking place between molten alloy samples and ZrO2 container during DSC tests were evaluated by structural analysis of the resulting interfaces using alloy samples solidified inside the ZrO2 containers. The conducted research has demonstrated methodological difficulties accompanying measurements of the thermophysical properties of Gd-rich alloys by the container-assisted DSC method, particularly when the tests are performed in flowing argon atmosphere with significantly reduced oxygen content. Under non-oxidizing conditions, the degradation of ZrO2 container can take place during DSC testing because the selected Gd40Ti30Zr30 alloy reacts with the ZrO2 to form a continuous interfacial reaction product layer. Under slightly oxidizing conditions, the gadolinium oxide formed in situ on the alloy surface, plays the role of a barrier for direct contact between molten alloy and container and thus may suppress or even prevent the degradation of the container and its subsequent strong bonding with the holder

EUROMAT 2019 Symposia on Processing

This issue of JMEP contains invited, peer-reviewed papers presented at the European Congress and Exhibition on Advanced Materials and Processes (EUROMAT 2019), held on September 1–5, 2019, in Stockholm, Sweden, in two symposia from the Area C “Processing”: C6 “Joining,” organized by Anna Zervaki (University of Thessaly, Greece), Ivan Kaban (IFW Dresden, Germany), and C. Sommitsch (Technische Universität Graz, Austria) C8 “Interface Design and Modelling, Wetting, and High-Temperature Capillarity,” organized by Pavel Protsenko (M.V. Lomonosov Moscow State University, Russian Federation), Fabrizio Valenza (CNR—ICMATE, Genoa, Italy), and Simeon Agathopoulos (University of Ioannina, Greece) The research works in the field of joining technologies, presented at the C6 symposium, concerned soldering, brazing, diffusion bonding, resistance spot welding, friction stir welding, and riveting techniques. The symposium C8 covered research topics on grain boundary wetting, surface energy of liquid metals and interfacial phenomena, considering fundamental as well as applied issues related to materials joining, and interface design. We wish to thank the authors for the written contributions and acknowledge the reviewers for their careful reading and evaluation of the manuscripts and valuable suggestions to improve the quality of the papers. We are grateful to the editor-in-chief of JMEP, Dr. Rajiv Asthana, and the ASM journal staff, including Mary Anne Fleming, senior content developer; Kate Doman, content developer (journals); and Vincent Katona, production coordinator; for the opportunity to publish the symposia contributions in this issue and for their professional and friendly support during the entire reviewing and publication process. We hope this collection will stimulate fresh thinking and promote further research on joining and interfacial phenomena