Ground-state energy and stability limit of small 3He drops

Small and stable drops of 3He atoms can only exist above a minimum number of particles, due to the combination of the 3He atom Fermi statistics and its light mass. An accurate estimation of this minimum number using microscopic theory has been difficult due to the inhomogeneous and fermionic nature of these systems. We present a diffusion Monte Carlo calculation of 3He drops with sizes near the minimum in order to determine the stability threshold. The results show that the minimum self-bound drop is formed by N=30 atoms with preferred orbitals for open shells corresponding to maximum value of the spin.Comment: 5 pages, 4 figure

Longitudinal spin Seebeck coefficient: heat flux vs. temperature difference method

The determination of the longitudinal spin Seebeck effect (LSSE) coefficient is currently plagued by a large uncertainty due to the poor reproducibility of the experimental conditions used in its measurement. In this work we present a detailed analysis of two different methods used for the determination of the LSSE coefficient. We have performed LSSE experiments in different laboratories, by using different setups and employing both the temperature difference method and the heat flux method. We found that the lack of reproducibility can be mainly attributed to the thermal contact resistance between the sample and the thermal baths which generate the temperature gradient. Due to the variation of the thermal resistance, we found that the scaling of the LSSE voltage to the heat flux through the sample rather than to the temperature difference across the sample greatly reduces the uncertainty. The characteristics of a single YIG/Pt LSSE device obtained with two different setups was $(1.143\pm0.007)\cdot 10^{-7}$ Vm/W and $(1.101\pm0.015)\cdot 10^{-7}$ Vm/W with the heat flux method and $(2.313\pm0.017)\cdot 10^{-7}$ V/K and $(4.956\pm0.005)\cdot 10^{-7}$ V/K with the temperature difference method. This shows that systematic errors can be considerably reduced with the heat flux method.Comment: PDFLaTeX, 10 pages, 6 figure

Equation of state description of the dark energy transition between quintessence and phantom regimes

The dark energy crossing of the cosmological constant boundary (the transition between the quintessence and phantom regimes) is described in terms of the implicitly defined dark energy equation of state. The generalizations of the models explicitly constructed to exhibit the crossing provide the insight into the cancellation mechanism which makes the transition possible.Comment: 3 pages, talk given at TAUP200

PENGEMBANGAN PROGRAM INTERVENSI DINI BERSUMBERDAYA KELUARGA PADA ANAK CEREBRAL PALSY DENGAN HAMBATAN KOMUNIKASI

Penelitian ini dilatarbelakangi oleh kurangnya pemahaman, penerimaan, dan sikap orang tua terhadap hambatan yang dihadapi anak. Hal ini berdampak pada kemampuan keluarga dalam memberikan layanan intervensi dini di rumah. Tujuan dari penelitian ini adalah untuk merumuskan program intervensi dini bersumber daya keluarga yang akan menjadi pedoman orang tua dalam melaksanakan intervensi. Penelitian ini menggunakan pendekatan kualitatif dengan metode deskriptif. Subjek dalam penelitian ini adalah satu keluarga yang memiliki anak Cerebral Palsy dengan hambatan komunikasi di Ciamis. Teknik pengumpulan data yang digunakan adalah observasi, wawancara, dan studi dokumentasi. Hasil penelitian menunjukkan bahwa: 1) anak memiliki hambatan komunikasi yang pencapaian perkembangan komunikasi verbalnya setara dengan anak usia 2-3 tahun dan usia kalender saat ini 5 tahun. 2) rendahnya tingkat pemahaman orangtua terhadap hambatan anak. 3). Rumusan program intervensi dini bersumber daya keluarga ini berdasarkan kondisi objektif serta kebutuhan keluarga dan anak. 4). tingkat pemahaman orang tua mengenai hambatan anak meningkat serta terjadi perubahan sikap dan perilaku orang tua kepada anak;--- The study was motivated by the lack of understanding, acceptance as well as the attitude of the parents toward their child’s obstacles. It somehow has an impact on family’s capacity to give early intervention support at home. This study was aimed at formulating an early intervention program to the child. The study used descriptive qualitative method involving a single family having a child suffering from Cerebral Palsy causing communication barrier at Ciamis. The techniques used in collecting the data were observations, interviews, and document analysis. The study revealed several findings as follows: 1) the child had communication barrier which made her communication verbal developmental stage was equal to 2-3 years old children. 2) The lack of understanding, acceptance and attitude of the parents toward their child’s communication barrier as well as the support in delivering early intervention at home. 3) The early intervention family-based program’s formulation was based on the objective condition as well as the needs’ of both the child and the parents. 4) The level understanding parents of the barriers to child increase and a change in attitudes and behavior of parents to child

The Running of the Cosmological and the Newton Constant controlled by the Cosmological Event Horizon

We study the renormalisation group running of the cosmological and the Newton constant, where the renormalisation scale is given by the inverse of the radius of the cosmological event horizon. In this framework, we discuss the future evolution of the universe, where we find stable de Sitter solutions, but also "big crunch"-like and "big rip"-like events, depending on the choice of the parameters in the model.Comment: 14 pages, 7 figures, minor improvements, references adde

Microcanonical mean-field thermodynamics of self-gravitating and rotating systems

We derive the global phase diagram of a self-gravitating $N$-body system enclosed in a finite three-dimensional spherical volume $V$ as a function of total energy and angular momentum, employing a microcanonical mean-field approach. At low angular momenta (i.e. for slowly rotating systems) the known collapse from a gas cloud to a single dense cluster is recovered. At high angular momenta, instead, rotational symmetry can be spontaneously broken and rotationally asymmetric structures (double clusters) appear.Comment: 4 pages, 4 figures; to appear in Phys. Rev. Let

Can electro-magnetic field, anisotropic source and varying Λ\Lambda be sufficient to produce wormhole spacetime ?

It is well known that solutions of general relativity which allow for traversable wormholes require the existence of exotic matter (matter that violates weak or null energy conditions [WEC or NEC]). In this article, we provide a class of exact solution for Einstein-Maxwell field equations describing wormholes assuming the erstwhile cosmological term $\Lambda$ to be space variable, viz., $\Lambda = \Lambda (r)$. The source considered here not only a matter entirely but a sum of matters i.e. anisotropic matter distribution, electromagnetic field and cosmological constant whose effective parts obey all energy conditions out side the wormhole throat. Here violation of energy conditions can be compensated by varying cosmological constant. The important feature of this article is that one can get wormhole structure, at least theoretically, comprising with physically acceptable matters.Comment: Some changes have been mad

Absolute properties of the binary system BB Pegasi

We present a ground based photometry of the low-temperature contact binary BB Peg. We collected all times of mid-eclipses available in literature and combined them with those obtained in this study. Analyses of the data indicate a period increase of 3.0(1) x 10^{-8} days/yr. This period increase of BB Peg can be interpreted in terms of the mass transfer 2.4 x 10^{-8} Ms yr^{-1} from the less massive to the more massive component. The physical parameters have been determined as Mc = 1.42 Ms, Mh = 0.53 Ms, Rc = 1.29 Rs, Rh = 0.83 Rs, Lc = 1.86 Ls, and Lh = 0.94 Ls through simultaneous solution of light and of the radial velocity curves. The orbital parameters of the third body, that orbits the contact system in an eccentric orbit, were obtained from the period variation analysis. The system is compared to the similar binaries in the Hertzsprung-Russell and Mass-Radius diagram.Comment: 17 pages, 3 figures, accepted for Astronomical Journa

Possible Enhancement of High Frequency Gravitational Waves

We study the tensor perturbations in a class of non-local, purely gravitational models which naturally end inflation in a distinctive phase of oscillations with slight and short violations of the weak energy condition. We find the usual generic form for the tensor power spectrum. The presence of the oscillatory phase leads to an enhancement of gravitational waves with frequencies somewhat less than 10^{10} Hz.Comment: 27 pages, 11 figures, LaTeX.2

Cosmological Evolution Across Phantom Crossing and the Nature of the Horizon

In standard cosmology, with the evolution of the universe, the matter density and thermodynamic pressure gradually decreases. Also in course of evolution, the matter in the universe obeys (or violates) some restrictions or energy conditions. If the matter distribution obeys strong energy condition (SEC), the universe is in a decelerating phase while violation of SEC indicates an accelerated expansion of the universe. In the period of accelerated expansion the matter may be either of quintessence nature or of phantom nature depending on the fulfilment of the weak energy condition (WEC) or violation of it. As recent observational evidences demand that the universe is going through an accelerated expansion so mater should be either quintessence or phantom in nature. In the present work we study the evolution of the universe through the phantom barrier (i.e. the dividing line between the quintessence and phantom era) and examine how apparent and event horizon change across the barrier. Finally, we investigate the possibility of occurrence of any singularity in phantom era.Comment: 7 pages and 4 figure