Reconstruction of general scalar-field dark energy models

The reconstruction of scalar-field dark energy models is studied for a general Lagrangian density $p(\phi, X)$, where $X$ is a kinematic term of a scalar field $\phi$. We implement the coupling $Q$ between dark energy and dark matter and express reconstruction equations using two observables: the Hubble parameter $H$ and the matter density perturbation $\delta_m$. This allows us to determine the structure of corresponding theoretical Lagrangian together with the coupling $Q$ from observations. We apply our formula to several forms of Lagrangian and present concrete examples of reconstruction by using the recent Gold dataset of supernovae measurements. This analysis includes a generalized ghost condensate model as a way to cross a cosmological-constant boundary even for a single-field case.Comment: 8 pages, 2 figure

Age problem in holographic dark energy

We study the age problem of the universe with the holographic DE model introduced in [21], and test the model with some known old high redshift objects (OHRO). The parameters of the model have been constrained using the SNIa, CMB and BAO data set. We found that the age of the old quasar APM 08 279+5255 at z = 3.91 can be described by the model.Comment: 13 page

APSIS - an Artificial Planetary System in Space to probe extra-dimensional gravity and MOND

A proposal is made to test Newton's inverse-square law using the perihelion shift of test masses (planets) in free fall within a spacecraft located at the Earth-Sun L2 point. Such an Artificial Planetary System In Space (APSIS) will operate in a drag-free environment with controlled experimental conditions and minimal interference from terrestrial sources of contamination. We demonstrate that such a space experiment can probe the presence of a "hidden" fifth dimension on the scale of a micron, if the perihelion shift of a "planet" can be measured to sub-arc-second accuracy. Some suggestions for spacecraft design are made.Comment: 17 pages, revtex, references added. To appear in Special issue of IJMP

Pregnancy-associated Spontaneous Pneumomediastinum: A Contemporary Review

Spontaneous pneumomediastinum (SPM), also referred to as mediastinal emphysema, is defined as the presence of free air in the mediastinal cavity without a clear and identifiable cause. Spontaneous pneumomediastinum, in general, is a relatively rare condition, more so in the setting of pregnancy or labor. Clinically, SPM may present as dyspnea, chest pain, and subcutaneous swelling, which may be of serious concern in the setting of pregnancy. A comprehensive literature review revealed that the majority of patients are primiparas, of a younger age, and have term or longer durations of pregnancy. The second stage of labor was found to be most commonly associated with the development of SPM. The pathomechanism suggests that performing the Valsalva maneuver during the active stages of labor may play a role in the development of SPM. Once diagnosed, patients with SPM in pregnancy are admitted to the hospital, treated conservatively, and followed until resolution. SPM must be diagnosed and managed promptly due to rare but serious complications. In addition, dyspnea or chest pain with an unknown etiology should include SPM in the differential diagnosis, especially in the setting of pregnancy and labor

Reconstructing the potentials for the quintessence and tachyon dark energy, from the holographic principle

We propose an holographic quintessence and tachyon models of dark energy. The correspondence between the quintessence and tachyon energy densities with the holographic density, allows the reconstruction of the potentials and the dynamics for the quintessence and tachyon fields, in flat FRW background. The proposed infrared cut-off for the holographic energy density works for two cases of the constant $\alpha$: for $\alpha<1$ we reconstructed the holographic quintessence model in the region before the $\omega=-1$ crossing for the EoS parameter. The cosmological dynamics for $\alpha>1$ was also reconstructed for the holographic quintessence and tachyon models.Comment: 21 pages, 18 figures, 2 table

Quantum effects, soft singularities and the fate of the universe in a braneworld cosmology

We examine a class of braneworld models in which the expanding universe encounters a "quiescent" future singularity. At a quiescent singularity, the energy density and pressure of the cosmic fluid as well as the Hubble parameter remain finite while all derivatives of the Hubble parameter diverge (i.e., ${\dot H}$, ${\ddot H}$, etc. $\to \infty$). Since the Kretschmann invariant diverges ($R_{iklm}R^{iklm} \to \infty$) at the singularity, one expects quantum effects to play an important role as the quiescent singularity is approached. We explore the effects of vacuum polarization due to massless conformally coupled fields near the singularity and show that these can either cause the universe to recollapse or, else, lead to a softer singularity at which $H$, ${\dot H}$, and ${\ddot H}$ remain finite while {\dddot H} and higher derivatives of the Hubble parameter diverge. An important aspect of the quiescent singularity is that it is encountered in regions of low density, which has obvious implications for a universe consisting of a cosmic web of high and low density regions -- superclusters and voids. In addition to vacuum polarization, the effects of quantum particle production of non-conformal fields are also likely to be important. A preliminary examination shows that intense particle production can lead to an accelerating universe whose Hubble parameter shows oscillations about a constant value.Comment: 19 pages, 3 figures, text slightly improved and references added. Accepted for publication in Classical and Quantum Gravit

Quintessence and phantom cosmology with non-minimal derivative coupling

We investigate cosmological scenarios with a non-minimal derivative coupling between the scalar field and the curvature, examining both the quintessence and the phantom cases in zero and constant potentials. In general, we find that the universe transits from one de Sitter solution to another, determined by the coupling parameter. Furthermore, according to the parameter choices and without the need for matter, we can obtain a Big Bang, an expanding universe with no beginning, a cosmological turnaround, an eternally contracting universe, a Big Crunch, a Big Rip avoidance and a cosmological bounce. This variety of behaviors reveals the capabilities of the present scenario.Comment: 8 pages, 8 figure

Expert System for Development Diagnosing Disease with Hepatitis Using Wamp

Expert systems are computer-based system that usesknowledge, facts and reasoning techniques in solving problemsusually only be solved by an expert in a particular field. Systemexperts to provide added value in technology to assist in handlingera of increasingly sophisticated information.Expert System produces output in the form of disease possiblehepatitis based on symptoms suffered by the user. This system alsomanampilkan amount of trust against the possibility of disease symptomskidney suffered by the user. The value of these beliefs isresults of calculations using the method-Factor Certainly.This expert system is designed with the view that considering the ease inin pengoprasiannya.Bibliography : (xiv + 93 + 33 Appendix

Expert System Development for Diagnose Disease Hepatitis Using Wamp 2003

Sistem pakar adalah sistem berbasis komputer yang menggunakan pengetahuan,fakta, dan tehnik penalaran dalam memecahkan masalah yang biasanya hanyadapat dipecahkan oleh seorang pakar dalam bidang tertentu. Sistem pakarmemberikan nilai tambah pada teknologi untuk membantu dalam menangani erainformasi yang semakin canggih. Sistem Pakar ini menghasilkan keluaranberupa kemungkinan penyakit hepatitis yang diderita berdasarkan gejala yangdirasakan oleh user. Sistem ini juga manampilkan besarnya kepercayaan gejalatersebut terhadap kemungkinan penyakit ginjal yang diderita oleh user.Besarnya nilai kepercayaan tersebut merupakan hasil perhitungan denganmenggunakan metode Certainly-Factor. Sistem pakar ini dirancang dengantampilan yang memperhatikan kemudahan di dalam pengoprasiannya