Matching the dark matter profiles of dSph galaxies with those of simulated satellites: a two parameter comparison

We compare the dark matter halos' structural parameters derived for four Milky Way dwarf spheroidal galaxies to those of subhalos found in cosmological $N$-body simulations. We confirm that estimates of the mass at a single fixed radius are fully consistent with the observations. However, when a second structural parameter such as the logarithmic slope of the dark halo density profile measured close to the half-light radius is included in the comparison, we find little to no overlap between the satellites and the subhalos. Typically the right mass subhalos have steeper profiles at these radii than measurements of the dSph suggest. Using energy arguments we explore if it is possible to solve this discrepancy by invoking baryonic effects. Assuming that feedback from supernovae can lead to a reshaping of the halos, we compute the required efficiency and find entirely plausible values for a significant fraction of the subhalos and even as low as 0.1%. This implies that care must be taken not to exaggerate the effect of supernovae feedback as this could make the halos too shallow. These results could be used to calibrate and possibly constrain feedback recipes in hydrodynamical simulations.Comment: 6 pages, 3 figures, submitted to ApJ

PENGEMBANGAN INSTRUMEN MATERI FISIKA KELAS XI UNTUK MENGUKUR KETERAMPILAN BERPIKIR KRITIS PESERTA DIDIK SMA NEGERI 8 MAKASSAR

Penelitian ini bertujuan untuk mengetahui prosedur dan menganalisis kualitas pengembangan instrumen materi fisika kelas XI agar dapat digunakan untuk mengukur keterampilan berpikir kritis peserta didik SMA. Jenis penelitian ini adalah penelitian pengembangan (Research and Development) dengan model pengembangan yang dikemukakan oleh Allen (1979) yang melalui 6 tahap yaitu plan the test, write item for each of the areas in the plan, administer all the item to a reasonably, conduct an item analysis, administer the revised test the another representative sample of examinee dan test standardization. Untuk mengetahui tujuan tersebut diperoleh koefisien validitas isi, koefisien reliabilitas, tingkat kesukaran dan daya pembeda butir instrumen. Subjek uji coba pada penelitian ini adalah peserta didik kelas XII IPA SMAN 8 Makassar terdiri dari 106 peserta  didik. Jumlah butir yang dikembangkan sebanyak 52 butir soal pilihan ganda. Hasil penelitian ini yaitu instrumen materi fisika kelas XI yang dikembangkan memiliki kualitas dengan kategori sangat layak berdasarkan hasil uji validasi ahli sebesar 0,96. Jumlah butir soal yang diujicobakan sebanyak 40 butir. Ujicoba instrumen dilakukan sebanyak dua kali dan menghasilkan koefisien reliabilitas sebesar 0,87 untuk ujicoba pertama dan ujicoba kedua. Dengan hasil analisis yang telah diperoleh maka instrumen materi fisika kelas XI yang dikembangkan tergolog valid dan reliabel baik secara teoretik maupun seara empirik. Sehingga menghasilkan instrumen tes yang baik dengan jumlah butir tes soal pilihan ganda sebanyak  33 butir soal. Kata Kunci : Instrumen Materi Fisika, Keterampilan Berpikir Kritis, Validitas, Reliabilita

Analisis Faktor Faktor yang Mempengaruhi Kepuasan Konsumen pada PT. Pln Sangatta

Awang Helmi,factor that influence coNsumer behavior for customer satisfaction of PT.PLN at sangatta under guidance of Mrs.DR.Titin Ruliana,SE,MM and Mrs.Mardiana,SE.MM. Consideration used byPLN Bontang to open a new Rayon at Sangatta is because the amount of electric power requirement from society and also company,besides the amont of samarinda townee which continue to increase PLN Rayon Upstream samarinda which stand from 2005 with 23.037 customers becomes an atracction because sangatta has the largest amount of townee compared to another city an east berneo province to market this PT.PLN sangatta branch need to now the factors the influence consumer behavior and satisfaction. The problem are the factors of services,service of goods,and Administration service will have significant effect to PT.PLN sangatta Custumer satisfaction,meanwhile the purpose of this research are to know and analyse consumer behavior,which consisted by services,service of good,and Administration service of PT.PLN Sangatta custumer satisfaction.analysis tool used multiple linear regretion with the help by SPSS version 10.00 program.regretion equation obtained is Y= 2.801+0.153X1 +0.165 X 2 + 0,188 X3 e. Based on the F test (concurrent test) obtained calculated F= 14.042 > table F = 2.467 so all of free variable have a significant influence to PT.PLN Sangatta branch customer satisfaction supported by R Square coefficient of 0,305 means 30,5 % influenced by the three free variables,and the other 69,5% Influenced by another Factor which not included in this research method. with the t test Obtained the three free variables t calculate>table t means zero hypothesis rejected and probability value of free variables<from alfa 5 % or 0,05 means all free variables are significant.free variable relation (X) namely services variables,service of goods and Administration services to tied variable (Y) is good custumer satisfaction showed by R correlation=0,552 approaching near 1 meanwhile from the consumer behavior factors, administration service have the largest influence to PT.PLN sangatta branch proved by value t calculated=2,554 and the largest standarited cooeficient beta=0,259. Based on this research showed the services,service of goods,and Administration service have significant influence to customer satisfaction and Administration service factor have the largest influence so the hipothesis accepted

The low mass end of the neutral gas mass and velocity width functions of galaxies in Λ\LambdaCDM

We use the high-resolution Aquarius cosmological dark matter simulations coupled to the semi-analytic model by Starkenburg et al. (2013) to study the HI content and velocity width properties of field galaxies at the low mass end in the context of $\Lambda$CDM. We compare our predictions to the observed ALFALFA survey HI mass and velocity width functions, and find very good agreement without fine-tuning, when considering central galaxies. Furthermore, the properties of the dark matter halos hosting galaxies, characterised by their peak velocity and circular velocity at 2 radial disk scalelengths overlap perfectly with the inferred values from observations. This suggests that our galaxies are placed in the right dark matter halos, and consequently at face value, we do not find any discrepancy with the predictions from the $\Lambda$CDM model. Our analysis indicates that previous tensions, apparent when using abundance matching models, arise because this technique cannot be straightforwardly applied for objects with masses $M_{vir} < 10^{10} M_{\odot}$.Comment: Accepted for publication in MNRAS, 9 pages, 8 figure

Sustainable machining of Ti-6Al-4V using cryogenic cooling: an optimized approach

Abstract Cryogenic machining is an effective, sustainable cooling approach in machining hard-to-cut materials. In this work, two multi-objective optimization techniques, namely; non-dominated sorting genetic algorithm, and grey relational analysis, were used to optimize the cutting performance during turning Ti-6Al-4V alloys under flood and cryogenic cooling. The machining performance was optimized in terms of surface roughness, material removal rate, tool performance and cutting forces. The optimal solutions, including cutting conditions and cooling technique, were determined for different machining strategies (i.e. roughing, finishing, and productivity). It was found that cryogenic cooling offers better cutting performance with a higher optimization index than flood approach

Constraining the Milky Way potential using the dynamical kinematic substructures

We present a method to constrain the potential of the non-axisymmetric components of the Galaxy using the kinematics of stars in the solar neighborhood. The basic premise is that dynamical substructures in phase-space (i.e. due to the bar and/or spiral arms) are associated with families of periodic or irregular orbits, which may be easily identified in orbital frequency space. We use the "observed" positions and velocities of stars as initial conditions for orbital integrations in a variety of gravitational potentials. We then compute their characteristic frequencies, and study the structure present in the frequency maps. We find that the distribution of dynamical substructures in velocity- and frequency-space is best preserved when the integrations are performed in the "true" gravitational potential.Comment: 2 pages, 4 figures, to appear in the proceedings of "Assembling the Puzzle of the Milky Way", Le Grand Bornand (Apr. 17-22, 2011