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

Self-gravitating clouds of generalized Chaplygin and modified anti-Chaplygin Gases

The Chaplygin gas has been proposed as a possible dark energy, dark matter candidate. As a working fluid in a Friedmann-Robertson-Walker universe, it exhibits early behavior reminiscent of dark matter, but at later times is more akin to a cosmological constant. In any such universe, however, one can expect local perturbations to form. Here we obtain the general equations for a self-gravitating relativistic Chaplygin gas. We solve these equations and obtain the mass-radius relationship for such structures, showing that only in the phantom regime is the mass-radius relationship large enough to be a serious candidate for highly compact massive objects at the galaxy core. In addition, we study the cosmology of a modified anti-Chaplygin gas. A self-gravitating cloud of this matter is an exact solution to Einstein's equations.Comment: 16 page

Modulating Notochordal Differentiation of Human Induced Pluripotent Stem Cells using Natural Nucleus Pulposus Tissue Matrix

Human induced pluripotent stem cells (hiPSCs) can differentiate into notochordal cell (NC)-like cells when cultured in the presence of natural porcine nucleus pulposus (NP) tissue matrix. The method promises massive production of high-quality, functional cells to treat degenerative intervertebral discs (IVDs). Based on our previous work, we further examined the effect of cell-NP matrix contact and culture medium on the differentiation, and further assessed the functional differentiation ability of the generated NC-like. The study showed that direct contact between hiPSCs and NP matrix can promote the differentiation yield, whilst both the contact and non-contact cultures can generate functional NC-like cells. The generated NC-like cells are highly homogenous regarding the expression of notochordal marker genes. A culture medium containing a cocktail of growth factors (FGF, EGF, VEGF and IGF-1) also supported the notochordal differentiation in the presence of NP matrix. The NC-like cells showed excellent functional differentiation ability to generate NP-like tissue which was rich in aggrecan and collagen type II; and particularly, the proteoglycan to collagen content ratio was as high as 12.5-17.5 which represents a phenotype close to NP rather than hyaline cartilage. Collectively, the present study confirmed the effectiveness and flexibility of using natural NP tissue matrix to direct notochordal differentiation of hiPSCs, and the potential of using the generated NC-like cells for treating IVD degeneration

Hydrothermal Deposition and Characterization of Heteroepitaxial BaTiO₃ Films on SrTiO₃ and LaAlO₃ Single Crystals

Heteroepitaxial BaTiO3 thin films were deposited in an aqueous solution under hydrothermal conditions on single crystal substrates of (100) SrTiO3 and (012) LaAlO3. The reactants consisted of fine TiO2 particles in a strongly alkaline solution of Ba(OH)2 at a temperature of 150°C. The growth of the films was studied by atomic force microscopy, high resolution scanning electron microscopy, and X-ray diffraction. The formation of the films occurred by nucleation of {001} faceted islands followed by three-dimensional growth of the islands to cover the substrate. Repeated hydrothermal treatment improved the film thickness and the surface coverage of the substrate at the expense of increased surface roughness. X-ray diffraction coupled with pole figure analysis showed that the films had the same in-plane and out-of-plane orientation as the substrate

Method for Fabricating Biocompatible Porous Titanium

A method for fabricating porous metal constructs (such as porous Ti constructs) which may be used as implants in bone repair is disclosed. The method employs a new saltbath sintering process coupled with conventional powder metallurgy technology which is capable of fabricating porous metal constructs with controlled porosity and pore size having a lower production cost than conventional powder metallurgy methods

Studij četiri- i više-dimenzijskih kozmoloških modela u Lyrovoj geometriji

Exact cosmological solutions for spherically symmetric models, both in four and higher dimensions are obtained within the framework of Lyra geometry. It is observed that there is no singularity at finite past in our four-dimensional model. For the five-dimensional model, the diminision of extra dimension with the evolution of the Universe is exhibited. The physical behaviour of the models is examined in vacuum (for the four-dimensional case) and in the presence of perfect fluids (for both four- and five-dimensional models).U okviru Lyrove geometrije izvodimo točna kozmološka rješenja za sferno-simetrične modele u četiri i više dimenzija. U našem 4-dimenzijskom modelu ne nalazi se singularnost u konačnoj prošlosti. U 5-dimenzijskom se modelu pokazuje nestanak dodatne dimenzije razvojem Svemira. Fizička se svojstva modela ispituju u vakuumu (4-dimenzijski model) i u prisustvu perfektne tekućine (za 4- i 5-dimenzijske modele)

Studij četiri- i više-dimenzijskih kozmoloških modela u Lyrovoj geometriji

Exact cosmological solutions for spherically symmetric models, both in four and higher dimensions are obtained within the framework of Lyra geometry. It is observed that there is no singularity at finite past in our four-dimensional model. For the five-dimensional model, the diminision of extra dimension with the evolution of the Universe is exhibited. The physical behaviour of the models is examined in vacuum (for the four-dimensional case) and in the presence of perfect fluids (for both four- and five-dimensional models).U okviru Lyrove geometrije izvodimo točna kozmološka rješenja za sferno-simetrične modele u četiri i više dimenzija. U našem 4-dimenzijskom modelu ne nalazi se singularnost u konačnoj prošlosti. U 5-dimenzijskom se modelu pokazuje nestanak dodatne dimenzije razvojem Svemira. Fizička se svojstva modela ispituju u vakuumu (4-dimenzijski model) i u prisustvu perfektne tekućine (za 4- i 5-dimenzijske modele)

Galactic rotation curves inspired by a noncommutative-geometry background

This paper discusses the observed at rotation curves of galaxies in the context of noncommutative geometry. The energy density of such a geometry is diffused throughout a region due to the uncertainty encoded in the coordinate commutator. This intrinsic property appears to be sufficient for producing stable circular orbits, as well as attractive gravity, without the need for dark matter.Comment: 12 pages, 3 figures. Published in Gen.Rel.Grav. 44 (2012) 905-91

Modeling galactic halos with predominantly quintessential matter

This paper discusses a new model for galactic dark matter by combining an anisotropic pressure field corresponding to normal matter and a quintessence dark energy field having a characteristic parameter $\omega_q$ such that $-1<\omega_q< -\frac{1}{3}$. Stable stellar orbits together with an attractive gravity exist only if $\omega_q$ is extremely close to $-\frac{1}{3}$, a result consistent with the special case studied by Guzman et al. (2003). Less exceptional forms of quintessence dark energy do not yield the desired stable orbits and are therefore unsuitable for modeling dark matter.Comment: 12 pages, 1 figur