Zero sound in a single component fermion - Bose Einstein Condensate mixture

The resonant dynamics of mediated interactions supports zero-sound in a cold atom degenerate mixture of a single component fermion gas and a Bose-Einstein condensate (BEC). We characterize the onset of instability in the phase separation of an unstable mixture and we find a rich collective mode structure for stable mixtures with one undamped mode that exhibits an avoided crossing and a Landau-damped mode that terminates.Comment: 4 pages, 2 figure

Membrane amplitude and triaxial stress in twisted bilayer graphene deciphered using first-principles directed elasticity theory and scanning tunneling microscopy

Twisted graphene layers produce a moir\'e pattern (MP) structure with a predetermined wavelength for given twist angle. However, predicting the membrane corrugation amplitude for any angle other than pure AB-stacked or AA-stacked graphene is impossible using first-principles density functional theory (DFT) due to the large supercell. Here, within elasticity theory we define the MP structure as the minimum energy configuration, thereby leaving the height amplitude as the only unknown parameter. The latter is determined from DFT calculations for AB and AA stacked bilayer graphene in order to eliminate all fitting parameters. Excellent agreement with scanning tunneling microscopy (STM) results across multiple substrates is reported as function of twist angle.Comment: to appear in Phys. Rev.

Penerapan Pendekatan Pembelajaran Visualization Auditory Kinestethic (Vak) untuk Meningkatkan Hasil Belajar IPA Siswa Kelas V Sdn 181 Pekanbaru

This research was held because of the low of science achievement offifth grade students of SDN 181 Pekanbaru. KKM (success criteria) assigned is 78 inthe school. The class consist of 37 students, who reached the KKM was just 14 students(37,84%). Whereas students who have not yet reached the KKM was 23 students(62.16%). Class average value was 58.91. To solve these problems then researcherimplement the learning approach of VAK. The purpose of this research is to improve thescience (IPA) learning achievement of fifth grade students of SDN 181 Pekanbaru withthe implementation of the learning approaches of VAK. The research results obtainedbasic score of average value was 58.91. Its increased 24.78% become 73.51 in cycle I.The average value of the students increased become 41.13% (83.14) In cycle II. On abase score of classical success learn IPA students is 37.84% (not succes) on cycle I.After the implement of VAK learning approach success studied classical students rosebecome 59.46% (not success) and success of classical learning of students increasedbecome 89.19% (success) in cycle II. The activity of the teacher in the first meeting ofthe cycle I was 62.50% by enough category. The second meeting was increased become75.00% by enough category. And at the third meeting of the cycle I rose become81.25% with good categories. At the first meeting of the cycle II teacher activityincreased to 87.50% by category. At the second meeting increased become 93.75% bycategory. The activity of the students at the first meeting of the cycle I was 56.25% byless category. In The second meeting increased become 62.50% with enough categories,and at the third meeting of the cycle I increased become 81.25% with good categories.At the first meeting of the cycle II activity of students increased become 87.50% by verygood category. At the second meeting increased become 93.75% by very good category.From this research it can be concluded that by the implementation of visualizationauditory kinestethic (vak) learning approach can improve science achievement of fifthgrade students of SDN 181 Pekanbaru

High Resolution BPM Upgrade for the ATF Damping Ring at KEK

A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring has been accomplished, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and processing, and also implements a new automatic gain error correction schema. The technical concept and realization as well as results of beam studies are presented.Comment: 3 pp. 10th European Workshop on Beam Diagnostics and Instrumentation for Particle Accelerators DIPAC 2011, 16-18 May 2011. Hamburg, German

Tinjauan Kekuatan Beton pada Usia Muda dengan Penambahan Polypropylene Fibre

Dewasa ini pemakaian beton sangat berkembang pesat pada kegiatan kontruksi, dikarenakan beton memiliki kelebihan mudah dibentuk sesuai keinginan, memiliki kuat tekan yang baik dan lain – lain. Tetapi beton memiliki kelemahan pada sifat yang getas dan kuat tarik yang rendah, sehingga kontruksi beton diberi tulangan untuk mengatasi pada bagian tarik. Maka diperlukan beton khusus untuk meningkatkan kuat tarik maupun kuat lentur yaitu beton serat. Beton serat adalah beton dengan bahan tambah serat. Dalam penelitian ini campuran beton menggunakan bahan tambah polypropylene fibre, sehingga diharapkan dapat meningkatkan kualitas beton pada umumnya dan khususnya pada kuat tarik belah dan kuat lentur. Polypropylene fibre menggunakan produk dari Sika dengan diameter 18 mikron dan panjang 12 mm. Pengujian ini meliputi pada kuat tekan, kuat tarik belah dan kuat lentur. Untuk pengujian kuat tekan dan kuat tarik belah menggunakan benda uji silinder dengan diameter 15 cm dan tinggi 30 cm, sedangkan kuat lentur menggunakan benda uji balok dengan panjang 60 cm, lebar 15 cm dan tinggi 15 cm. Benda uji terdiri dari tiga buah silinder dan tiga buah balok untuk masing - masing pengujian. Dari pengujian slump dapat disimpulkan tidak ada Perubahan berarti dalam penggunanan polypropylene fibre. Dan dari pengujian kuat tekan, kuat tarik belah dan kuat lentur di dapatkan nilai optimum pada beton normal ditambah polypropylene fibre. Pada kuat tekan terjadi peningkatan sebesar 4,44 % dibandingkan beton normal (N), sedangkan pada kuat tarik belah terjadi peningkatan sebesar 16,96% dibandingkan beton normal (N), dan pada kuat lentur terjadi peningkatan sebesar 16,47 % dibandingkan beton normal (N)

JSC-1: Lunar Simulant of Choice for Geotechnical Applications and Oxygen Production

Lunar simulant JSC-1 was produced as the result of a workshop held in 1991 to evaluate the status of simulated lunar material and to make recommendations on future requirements and production of such material (McKay et al., 1991). JSC-1 was prepared from a welded tuff that was mined, crushed, and sized from the Pleistocene San Francisco volcanic field, northern Arizona. As the initial production of approxiamtely 12,300kgs is nearly depleted, new production has commenced. The mineralogy and chemical properties of JSC-1 are described in McKay et al. (1994) and Hill et al. (this volume); description of its geotechnical properties appears in Klosky et al. (1996). Although other lunar-soil simulants have been produced (e.g., MLS-1: Weiblen et al., 1990; Desai et al., 1992; Chua et al., 1994), they have not been as well standardized as JSC-I; this makes it difficult to standardize results from tests performed on these simulants. Here, we provide an overview of the composition, mineralogy, strength and deformation properties, and potential uses of JSC-1 and outline why it is presently the 'lunar simulant of choice' for geotechnical applications and as a proxy for lunar-oxygen production

Formation of Nanophase Iron in Lunar Soil Simulant for Use in ISRU Studies

For the prospective return of humans to the Moon and the extensive amount of premonitory studies necessary, large quantities of lunar soil simulants are required, for a myriad of purposes from construction/engineering purposes all the way to medical testing of its effects from ingestion by humans. And there is only a limited and precious quantity of lunar soil available on Earth (i.e., Apollo soils) - therefore, the immediate need for lunar soil simulants. Since the Apollo era, there have been several simulants; of these JSC-1 (Johnson Space Center) and MLS-1 (Minnesota Lunar Simulant) have been the most widely used. JSC-1 was produced from glassy volcanic tuff in order to approximate lunar soil geotechnical properties; whereas, MLS-1 approximates the chemistry of Apollo 11 high-Ti soil, 10084. Stocks of both simulants are depleted, but JSC-1 has recently gone back into production. The lunar soil simulant workshop, held at Marshall Space Flight Center in January 2005, identified the need to make new simulants for the special properties of lunar soil, such as nanophase iron (np-Fe(sup 0). Hill et al. (2005, this volume) showed the important role of microscale Fe(sup 0) in microwave processing of the lunar soil simulants JSC-1 and MLS-1. Lunar soil is formed by space weathering of lunar rocks (e.g., micrometeorite impact, cosmic particle bombardment). Glass generated during micrometeorite impact cements rock and mineral fragments together to form aggregates called agglutinates, and also produces vapor that is deposited and coats soil grains. Taylor et al. (2001) showed that the relative amount of impact glass in lunar soil increases with decreasing grain size and is the most abundant component in lunar dust (less than 20 micrometer fraction). Notably, the magnetic susceptibility of lunar soil also increases with the decreasing grain size, as a function of the amount of nanophase-sized Fe(sup 0) in impact-melt generated glass. Keller et al. (1997, 1999) also discovered the presence of abundant np-Fe(sup 0) particles in the glass patinas coating most soil particles. Therefore, the correlation of glass content and magnetic susceptibility can be explained by the presence of the np-Feo particles in glass: small particles contain relatively more np-Fe(sup 0) as glass coatings because the surface area versus mass ratio of the grain size is so increased. The magnetic properties of lunar soil are important in dust mitigation on the Moon (Taylor et al. 2005). Thus material simulating this property is important for testing mitigation methods using electromagnetic field. This np- Fe(sup 0) also produces a unique energy coupling to normal microwaves, such as present in kitchen microwave ovens. Effectively, a portion of lunar soil placed in a normal 2.45 GHz oven will melt at greater than 1200 C before your tea will boil at 100 C, a startling and new discovery reported by Taylor and Meek (2004, 2005). Several methods have been investigated in attempts to make nanophase-sized Feo dispersed within silicate glass; like in the lunar glass. We have been successful in synthesizing such a product and continue to improve on our recipe. We have performed extensive experimentation on this subject to date. Ultimately it will probably be necessary to add this np-Fe(sup 0) bearing silicate glass to lunar soil stimulant, like JSC-1, to actually produce the desired magnetic and microwave coupling properties for use in appropriate ISRU experimentation

Degenerate fermion gas heating by hole creation

Loss processes that remove particles from an atom trap leave holes behind in the single particle distribution if the trapped gas is a degenerate fermion system. The appearance of holes increases the temperature and we show that the heating is (i) significant if the initial temperature is well below the Fermi temperature $T_{F}$, and (ii) increases the temperature to $T \geq T_{F}/4$ after half of the system's lifetime, regardless of the initial temperature. The hole heating has important consequences for the prospect of observing Cooper-pairing in atom traps.Comment: to be published in PR