Weak-Light Ultraslow Vector Optical Solitons via Electromagnetically Induced Transparency

We propose a scheme to generate temporal vector optical solitons in a lifetime broadened five-state atomic medium via electromagnetically induced transparency. We show that this scheme, which is fundamentally different from the passive one by using optical fibers, is capable of achieving distortion-free vector optical solitons with ultraslow propagating velocity under very weak drive conditions. We demonstrate both analytically and numerically that it is easy to realize Manakov temporal vector solitons by actively manipulating the dispersion and self- and cross-phase modulation effects of the system.Comment: 4 pages, 4 figure

Magnetotransport properties of a magnetically modulated two-dimensional electron gas with the spin-orbit interaction

We study the electrical transport properties of a two-dimensional electron gas with the Rashba spin-orbit interaction in presence of a constant perpendicular magnetic field $(B_0 \hat z)$ which is weakly modulated by ${\bf B_1} = B_1 \cos (q x) \hat z$, where $B_1 \ll B_0$ and $q = 2 \pi/a$ with $a$ is the modulation period. We obtain the analytical expressions of the diffusive conductivities for spin-up and spin-down electrons. The conductivities for spin-up and spin-down electrons oscillate with different frequencies and produce beating patterns in the amplitude of the Weiss and Shubnikov-de Haas oscillations. We show that the Rashba strength can be determined by analyzing the beating pattern in the Weiss oscillation. We find a simple equation which determines the Rashba spin-orbit interaction strength if the number of Weiss oscillations between any two successive nodes is known from the experiment. We compare our results with the electrically modulated 2DEG with the Rashba interaction. For completeness, we also study the beating pattern formation in the collisional and the Hall conductivities.Comment: 11 pages, 5 figures, re-written with new result

Investigating The Relationship Between Gross Domestic Product (GDP) and Household Consumption Expenditure (HCE) In Two SAARC Countries: Nepal and Pakistan

Abstract This study examines the matter of trends (level and slope), cycle and irregular components in the Gross Domestic Product (GDP) and Household Consumption Expenditure (HCE) of two SAARC (South Asian Association for Regional Cooperation) countries: Nepal and Pakistan. SAARC countries produce GDP (PPP) US$9.9 trillion and GDP (Nominal) US$ 2.9 trillion and constitute 9.12% of global economy as of 2015. The mentioned two countries from this region are selected due to their importance in the SAARC region and their challenges during last few decades i.e. Political crisis and natural disasters. In this study the multivariate unobserved components model is used to decompose the GDP and HCE and examine the relationships between these two variables of Nepal and Pakistan. The time period of this study is 1970-2014 and Kushnirs statistical data is employed. The maximum likelihood smoother is employed in the trend plus stochastic cycle methodology of Koopman et al. (2009) to estimate the model. It is found here that there have no deficiencies in the diagnostics of normality, auxiliary, prediction, and forecast. And residual diagnostics also present that it is nicely fitted with this model. Empirical results clearly show that there have strong correlations between the GDP and HCE in irregular components in both the countries of Nepal and Pakistan. Finally, in both slope and cycle, the correlations between GDP and HCE of Nepal and Pakistan are found perfectly positive in the short and long run

Ga+, In+ and Tl+ Impurities in Alkali Halide Crystals: Distortion Trends

A computational study of the doping of alkali halide crystals (AX: A = Na, K; X = Cl, Br) by ns2 cations (Ga+, In+ and Tl+) is presented. Active clusters of increasing size (from 33 to 177 ions) are considered in order to deal with the large scale distortions induced by the substitutional impurities. Those clusters are embedded in accurate quantum environments representing the surrounding crystalline lattice. The convergence of the distortion results with the size of the active cluster is analyced for some selected impurity systems. The most important conclusion from this study is that distortions along the (100) and (110) crystallographic directions are not independent. Once a reliable cluster model is found, distortion trends as a function of impurity, alkali cation and halide anion are identified and discussed. These trends may be useful when analycing other cation impurities in similar host lattices.Comment: LaTeX file. 7 pages and 2 pictures. Accepted for publication in J. Chem. Phy

Pemodelan Dan Estimasi Ketidakpastian Pengukuran Uji Kekuatan Sobek Kain Metoda Pendulum (Elmendorf)

Telah dilakukan penelitian tentang estimasi ketidakpastian pengukuran pada uji kekuatan sobek kain metoda pendulum (Elmendorf). Tujuan penelitian ini adalah untuk mendapatkan nilai dan parameter-parameter sumber ketidakpastian pengukuran pada uji kekuatan sobek kain metoda pendulum (Elmendorf). Dalam mengestimasi ketidakpastian pengukuran diperlukan model pengukuran yang merupakan fungsi yang menghubungkan besaran yang sedang diukur dengan besaran masukan. Pembuatan model pengukuran memerlukan pemahaman tentang proses utama dan hubungannya dengan besaran yang diukur. Proses utama uji sobek kain metoda pendulum (Elmendorf) yang berpengaruh pada besarnya gaya yang dibutuhkan untuk meneruskan sobekan adalah pemolaan dengan pola contoh uji (d), pemberian sobekan awal (s) hasil uji sobek kain (F) dan metoda uji (b). Dengan meneliti proses utama tersebut diperoleh formulasi perhitungan gaya sobek yang mengkaitkan faktor-faktor tersebut, yaitu : . Mengacu pada formulasi tersebut maka komponen-komponen ketidakpastian pengukuran dapat diidentifikasi, yaitu : repeatability hasil uji, penunjukan gaya pada alat uji sobek (alat elmendorf), panjang contoh uji, panjang sobekan yang diteruskan, panjang sobekan awal dan konstanta ketetapan ukuran pada metode uji (SNI ISO 13937-1:2010). Dari keenam komponen tersebut yang memberikan kontribusi yang cukup besar pada ketidakpastian pengukuran yang dihasilkan adalah ketidakpastian repetability hasil pengujian, ketidakpastian panjang sobekan yang diteruskan dan ketidakpastian konstanta. Dengan diketahuinya faktor-faktor ketidakpastian, maka ketidakpastian pengukuran uji kekuatan sobek kain metoda pendulum (Elmendorf) dapat diestimasi

Pressure-Induced Simultaneous Metal-Insulator and Structural-Phase Transitions in LiH: a Quasiparticle Study

A pressure-induced simultaneous metal-insulator transition (MIT) and structural-phase transformation in lithium hydride with about 1% volume collapse has been predicted by means of the local density approximation (LDA) in conjunction with an all-electron GW approximation method. The LDA wrongly predicts that the MIT occurs before the structural phase transition. As a byproduct, it is shown that only the use of the generalized-gradient approximation together with the zero-point vibration produces an equilibrium lattice parameter, bulk modulus, and an equation of state that are in excellent agreement with experimental results.Comment: 7 pages, 4 figures, submitted to Europhysics Letter

On asymmetry in inclusive pion production

On the basis of the mechanism proposed for one-spin asymmetries in inclusive hadron production we specify an $x$--dependence of asymmetries in inclusive processes of pion production. The main role in generation of this asymmetry belongs to the orbital angular momentum ofquark-antiquark cloud in internal structure of constituent quarks. The $x$--dependence of asymmetries in the charged pion production at large $x$ reflects the corresponding dependence of constituent quark polarization in the polarized proton.Comment: LaTeX, 8 pages, 3 figures. One figure added, as it appears in Phys. Rev.

Antinociceptive, Anti-Inflammatory, and Antipyretic Activity of Mangrove Plants: A Mini Review

Mangrove plants are specialised plants that grow in the tidal coasts of tropic and subtropic regions of the world. Their unique ecology and traditional medicinal uses of mangrove plants have attracted the attention of researchers over the years, and as a result, reports on biological activity of mangrove plants have increased significantly in recent years. This review has been set out to compile and appraise the results on antinociceptive, anti-inflammatory, and antipyretic activity of mangrove plants. While the Web of Knowledge, Google Scholar, and PubMed were the starting points to gather information, other pieces of relevant published literature were also adequately explored for this purpose. A total of 29 reports on 17 plant species have been found to report such activities. While 19 reports were on the biological activity of the crude extracts, 10 reports identified the active compound(s) of various chemical classes of natural products including terpenes, steroids, and flavonoids. This review finds that antinociceptive, anti-inflammatory, and antipyretic activity appears to be widespread in mangrove plants

Magnetic field induced orientation of superconducting MgB2_2 crystallites determined by X-ray diffraction

X-ray diffraction studies of fine polycrystalline samples of MgB$_2$ in the superconducting state reveal that crystals orient with their \emph{c}-axis in a plane normal to the direction of the applied magnetic field. The MgB$_2$ samples were thoroughly ground to obtain average grain size 5 - 10 $\mu$m in order to increase the population of free single crystal grains in the powder. By monitoring Bragg reflections in a plane normal to an applied magnetic field we find that the powder is textured with significantly stronger (\emph{0,0,l}) reflections in comparison to (\emph{h,k,0}), which remain essentially unchanged. The orientation of the crystals with the \emph{ab}-plane parallel to the magnetic field at all temperatures below $T_c$ demonstrates that the sign of the torque under magnetic field does not alter, in disagreement with current theoretical predictions