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

INVESTIGATION OF THE CAUSES OF MARITIME ACCIDENTS IN THE INLAND WATERWAYS OF BANGLADESH

Water transport is the proven cheapest and safest mode of transportation but it is the agent of catastrophe in Bangladesh. The overall scenario of Bangladesh inland water transport has been studied. The form of occurrences of maritime accidents in the inland waterways of Bangladesh may be categorized based on mode of failure. Data analysis of major accidents shows that prevention of passenger vessels’ accident will drastically reduce the number of casualties in Bangladesh Inland Waterways where the two repeatedly reported causes of accidents are overloading and inclement weather. Literature review shows that analyses were carried out mostly to investigate the mechanism of capsizing due to violation of “The Inland Shipping Laws and Rules”. To enlighten the roles of professionals like Naval Architects and Law Enforcing Agencies, the reasons behind the accidents in Bangladesh Inland Waterways have been simplified and the nature of actions required for preventing the accidents have been identified from practical point of view. The effect of consideration of overloading condition and higher wind pressure in design has been studied and found that it will have adverse effect on the socio-economical condition of Bangladesh. Role of proper design and construction has been identified by dividing the accidental phenomenon into two phases, capsizing and sinking of vessels

A simple heuristic for linear sequencing of machines in layout design

This paper presents a simple heuristic to determine a common linear machine sequence for multiple products with different operation sequences and a limited number of duplicate machine types available for the job. The heuristic is based on minimisation of the total flow distance travelled by a product on the linear machine sequence. It is assumed that the flows of products are allowed only in the forward direction, either in-sequence or by-pass. It is also assumed that backtrack movements are not allowed. The effectiveness of the proposed heuristic is demonstrated through the solutions of two typical layout design problems taken from the literature. Subsequently, a number of additional problems are solved and their results are compared with the results applying existing methods. The results indicate that the proposed method can be an effective tool in solving layout design problems

Quantum limits to center-of-mass measurements

We discuss the issue of measuring the mean position (center-of-mass) of a group of bosonic or fermionic quantum particles, including particle number fluctuations. We introduce a standard quantum limit for these measurements at ultra-low temperatures, and discuss this limit in the context of both photons and ultra-cold atoms. In the case of fermions, we present evidence that the Pauli exclusion principle has a strongly beneficial effect, giving rise to a 1/N scaling in the position standard-deviation -- as opposed to a $1/\sqrt{N}$ scaling for bosons. The difference between the actual mean-position fluctuation and this limit is evidence for quantum wave-packet spreading in the center-of-mass. This macroscopic quantum effect cannot be readily observed for non-interacting particles, due to classical pulse broadening. For this reason, we also study the evolution of photonic and matter-wave solitons, where classical dispersion is suppressed. In the photonic case, we show that the intrinsic quantum diffusion of the mean position can contribute significantly to uncertainties in soliton pulse arrival times. We also discuss ways in which the relatively long lifetimes of attractive bosons in matter-wave solitons may be used to demonstrate quantum interference between massive objects composed of thousands of particles.Comment: 12 pages, 6 figures. Submitted to PRA. Revised to include more references as well as a discussion of fermionic center-of-mas

Asymmetric Thermal Lineshape Broadening in a Gapped 3-Dimensional Antiferromagnet - Evidence for Strong Correlations at Finite Temperature

It is widely believed that magnetic excitations become increasingly incoherent as temperature is raised due to random collisions which limit their lifetime. This picture is based on spin-wave calculations for gapless magnets in 2 and 3 dimensions and is observed experimentally as a symmetric Lorentzian broadening in energy. Here, we investigate a three-dimensional dimer antiferromagnet and find unexpectedly that the broadening is asymmetric - indicating that far from thermal decoherence, the excitations behave collectively like a strongly correlated gas. This result suggests that a temperature activated coherent state of quasi-particles is not confined to special cases like the highly dimerized spin-1/2 chain but is found generally in dimerized antiferromagnets of all dimensionalities and perhaps gapped magnets in general

Barriers and Enablers for Industry 4.0 in SMEs: A Combined Integration Framework

Although Industry 4.0 was introduced a decade ago, many small and medium-sized enterprises (SMEs) still have not adopted several technologies. Therefore, integrating SMEs along horizontal, vertical, and end-to-end engineering dimensions remains challenging. Due to the importance of SMEs for industrial value chains, understanding SMEs' barriers and respective enablers for Industry 4.0 integration is vital. Applying a multiple case study approach, this paper investigates their experience in Industry 4.0 through technological, organizational, and environmental factors. We aggregate the barriers and respective enablers to Industry 4.0 into an integration framework, which helps to understand Industry 4.0 in SMEs from a broader viewpoint inside these firms, upstream and downstream supply chains, and beyond manufacturing. The findings show that the success of Industry 4.0 integration is more oriented toward operational benefits than strategic advantages and depends upon how these technologies are integrated with various stakeholders across the supply chain, such as original equipment manufacturers, R&D agencies, or sub-suppliers

Blood pressure and its associated factors: a comparative study among rural and urban adolescents in Bangladesh

Background: Hypertension in adolescents may lead to irreversible damages in vital organs, such as heart, brain, kidney and may cause death if treatments are not given despite early diagnosis. The aim of this study is to identify the status of blood pressure and its associated factors among adolescents.Methods: It was a cross-sectional study. 810 adolescents of 8 schools and colleges in Chittagong district were collected by stratified cluster sampling technique. Ages of the respondents were 14 to 19. Status of Blood pressure and its associated factors in urban and rural area were the main outcome of interest.Results: The study found the significant difference in physical activities and overweight statistics between urban and rural adolescents (P<0.001). Obesity was found only in the urban area that was 1.2%. The mean systolic blood pressure (114.53 mmHg, 110.61 mmHg) and mean diastolic blood pressure (69.87 mmHg, 68.58 mmHg) of boys and girls in urban respondents were more than rural (109.79 mmHg, 68.97 mmHg and 105.02 mmHg, 67.941 mmHg respectively) and was statistically significant (P<0.001). The mean SBP and DBP were 126 mmHg and 79 mmHg respectively among obese. In the study prevalence of hypertension was 1.5% in urban adolescents and 0.2% in rural adolescents. Consumption of fast food, living area, physical activity, paternal hypertension and BMI were found significantly associated (p<0.05) with hypertension among urban adolescents.Conclusions: The results suggest that hypertension and pre-hypertension is an important public health problem among adolescents in urban than rural. The main associated factors are fast food consumption, living area, physical activity, paternal hypertension and BMI

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.

Effects of micronutrient and spacing on growth and chlorophyll content of rice

An experiment was carried out at the research field of the Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU).There were four nutrient treatments i.e., E1= NPKS recommended dose; E2= NPKS + Zn 5 Kg ha-1; E3= NPKS + Zn (5 Kg ha-1) + B (3 Kg ha-1) E4= NPKS + Zn (5 Kg ha-1) + B (3 Kg ha-1) + Mo (2 Kg ha-1) and three spacing S1= 20 x 10 cm2; S2 = 20 x 15 cm2 and S3 = 20 x 20 cm2.Micronutrient and spacing combined had a distinct positive response in crop growth attributes and chlorophyll content of rice. The tallest plant height (147.0 cm) and root length (13.50 cm) highest panicle length (22.56 cm) was attained in the treatment E2S3 but the maximum tillers per hill (14.95) and effective panicle per hill (14.17) were recorded in treatment E2S2. Physiological parameter i.e., LAI, CGR, RGR, NAR, total chlorophyll content of rice also responded significantly and the appropriate combination was E4S2treatment. Based on vegetative growth, physiological parameters and yield attributes the treatment combination E4S2 showed the best performance

Spinon confinement in a quasi one dimensional anisotropic Heisenberg magnet

Confinement is a process by which particles with fractional quantum numbers bind together to form quasiparticles with integer quantum numbers. The constituent particles are confined by an attractive interaction whose strength increases with increasing particle separation and as a consequence, individual particles are not found in isolation. This phenomenon is well known in particle physics where quarks are confined in baryons and mesons. An analogous phenomenon occurs in certain magnetic insulators; weakly coupled chains of spins S=1/2. The collective excitations in these systems is spinons (S=1/2). At low temperatures weak coupling between chains can induce an attractive interaction between pairs of spinons that increases with their separation and thus leads to confinement. In this paper, we employ inelastic neutron scattering to investigate the spinon confinement in the quasi-1D S=1/2 XXZ antiferromagnet SrCo2V2O8. Spinon excitations are observed above TN in quantitative agreement with established theory. Below TN the pairs of spinons are confined and two sequences of meson-like bound states with longitudinal and transverse polarizations are observed. Several theoretical approaches are used to explain the data. A new theoretical technique based on Tangent-space Matrix Product States gives a very complete description of the data and provides good agreement not only with the energies of the bound modes but also with their intensities. We also successfully explained the effect of temperature on the excitations including the experimentally observed thermally induced resonance between longitudinal modes below TN ,and the transitions between thermally excited spinon states above TN. In summary, our work establishes SrCo2V2O8 as a beautiful paradigm for spinon confinement in a quasi-1D quantum magnet and provides a comprehensive picture of this process.Comment: 17 pages, 18 figures, submitted to PR