Opposing actions of BMP3 and TGF beta 1 in human bone marrow stromal cell growth and differentiation

BMP3 and TGF beta 1 were found to induce opposite effects on human bone marrow stromal cells both in cell proliferation and cell differentiation and on calcium deposition onto the extracellular matrix. Moreover, BMP3 may exert, in part, the inhibitory effect of TGF beta 1 through decreasing the affinity of TGF-beta for its receptors which are now identified in these human bone cells.     

The role of lipoproteins in the delivery of tumour-targeting photosensitizers

1. Serum lipoproteins play an important role in the in vivo transport of several porphyrinoid derivatives having a moderate or high degree of hydrophobicity. 2. There appears to exist a correlation between the extent of photosensitizer association with low-density lipoproteins (LDL) and the efficiency of tumour targeting by some classes of photosensitizers, such as differently sulphonated porphyrins and phthalocyanines, haematoporphyrin dialkylethers and unsubstituted phthalocyanines and naphthalocyanines. 3. In all cases, LDL-carried photosensitizers are preferentially released to malignant cells; hence, direct cell damage appears to be the major determinant of tumour damage consequent to photodynamic therapy. 4. Present evidence suggests that the LDL-associated photosensitizer is accumulated by tumour cells largely via a receptor-mediated endocytotic process. 5. Thus, the use of delivery systems for orientating a systemically injected photosensitizer towards lipoproteins has been explored; promising results have been obtained by incorporation of the dye into liposomal vesicles, oil emulsions or inclusion complexes, as well as by precomplexation of the dye with LDL. 6. Moreover, a suitable choice of the chemical constituents of the delivery system and the experimental conditions allows one to modulate the photosensitizer distribution among the different lipoproteins. 7. The occurrence of tumour-targeting strategies other than the LDL pathway is briefly discussed.     

Growth kinetics of monofilamentary Nb3Sn and V3Ga synthesized by solid-state diffusion

Studies of growth kinetics of Nb₃Sn and V₃Ga formation have been carried for mono-filamentary composites of niobium and vandium filaments embedded in bronze wires containing varying concentrations of tin and gallium, respectively. The samples are diffusion reacted at different temperatures and for different lengths of time and the thickness and the microstructure of the resulting A-15 layer are investigated using optical and scanning electron microscopy techniques. The results are discussed in the light of the analytical model previously proposed by the present authors and it is shown that while the rate controlling step for the formation of Nb₃Sn is diffusion of tin through the bronze matrix, for V₃Ga it is the diffusion of gallium through the grain boundaries of the compound layer. The data are used to calculate the activation energies for Nb₃Sn and V₃Ga formation.     

Provable secure lightweight hyper elliptic curve‐based communication system for wireless sensor networks

It is widely believed that hyper elliptic curve cryptosystems (HECCs) are not attractive for wireless sensor network because of their complexity compared with systems based on lower genera, especially elliptic curves. Our contribution shows that for low cost security applications HECs cryptosystems can outperform elliptic curve cryptosystems. The aim of this paper is to propose a discrete logarithm problem‐based lightweight secure communication system using HEC. We propose this for different genus curves over varied prime fields performing a full scale study of their adaptability to various types of constrained networks. Also, we propose to evaluate the performance of the protocol for computational times with respect to different genus for main operations like Jacobian, Divisor identifications, key generation, signature generation/verification, message encryption, and decryption by changing the size of the field. A formal security model was established based on the hardness of HEC‐Decision Diffie‐Hellman (HEC‐DDH). Finally, a comparative analysis with ECC‐based cryptosystems was made, and satisfactory results were obtained.     

Hydrogen refueling station compression and storage optimization with tube-trailer deliveries

Hydrogen refueling stations require high capital investment, with compression and storage comprising more than half of the installed cost of refueling equipment. Refueling station configurations and operation strategies can reduce capital investment while improving equipment utilization. Argonne National Laboratory developed a refueling model to evaluate the impact of various refueling compression and storage configurations and tube trailer operating strategies on the cost of hydrogen refueling. The modeling results revealed that a number of strategies can be employed to reduce fueling costs. Proper sizing of the high-pressure buffer storage reduces the compression requirement considerably, thus reducing refueling costs. Employing a tube trailer to initially fill the vehicle's tank also reduces the compression and storage requirements, further reducing refueling costs. Reducing the cut-off pressure of the tube trailer for initial vehicle fills can also significantly reduce the refueling costs. Finally, increasing the trailer's return pressure can cut refueling costs, especially for delivery distances less than 100 km, and in early markets, when refueling stations will be grossly underutilized.     

First-order algorithm with three clusters of optical flow vectors

The first-order algorithm is an algorithm for recovering the motion parameters from a single optical flow field. It compares the spatial derivatives, to first order, of the optical flow field obtained from two different parts of the field of view and obtains a linear constraint on the direction of the translational velocity. We modify this algorithm to incorporate the spatial derivatives, to first order, of the optical flow field obtained from a third part of the field of view, and thereby obtain two further linear constraints on the direction of the translational velocity. Only two linear constraints are required to identify the direction of the translational velocity. Therefore, with three linear constraints, there are three ways of estimating the direction of the translational velocity. Although all three estimates are derived from the same set of information, we show that the three estimates are not, in general, equally stable. We assume that each cluster of flow vectors arises from a plane in the environment and show that a linear constraint is most stable when it emanates from a pair of parallel planes, with the camera between them. We also identify the relative orientations of the clusters of flow vectors that maximize and minimize the stability of the linear constraint that they give rise to. © 1996 John Wiley & Sons, Inc.     

Analysis of camera behavior during tracking

A camera is mounted on a moving robot and can rotate, relative to the robot, about two axes. We show how the optical flow field can be used to control the camera's motion to keep a target at the center of the camera's field of view, but that this is not always possible when the target lies close to the plane defined by the camera's two axes of rotation. When the target is held at the center of the camera's field of view, then the magnitude of the camera's angular velocity about one axis never exceeds the magnitude of the flow vector associated with the target, but the angular velocity about the other axis is dependent on the inverse distance of the target from this axis, and hence can become large as this distance becomes small. Situations, where the magnitudes of the camera's angular velocity and acceleration become large, are considered in the special case where the relative motion between the robot and its environment is purely translational. The tracking strategy is experimentally evaluated using computer-generated optical flow fields     

Fractal Representation of Soil Cohesion

Evaluation of soil cohesion is usually based on measurements made on laboratory-scale samples. Some previous studies point out a decreasing trend in cohesion as the test specimen size increases. Although this trend is, in general, attributed qualitatively to fractures and macropores associated with larger samples, no rational basis has been put forth thus far to upscale cohesion. In this study, the soil medium is idealized as a self-similar fractal system, which contains successive groups of pores that can be scaled in size with respect to each other. A simple relationship between cohesion and sample size is developed using fractal principles. The relationship is demonstrated using experimental data. The fractal dimension of the soil medium, which enters in this relationship, is of both theoretical and practical importance. It draws out the analogy between scale-dependency of cohesion and porosity and enables one to make judgments on the characteristic specimen size required in the assessment of soil cohesion.     

Synthesis of Fe-Si-B-Mn-based nanocrystalline magnetic alloys with large coercivity by high energy ball milling

Alloys of Fe-Si-B with varying compositions of Mn were prepared using high energy planetary ball mill for maximum duration of 120 h. X-ray diffraction (XRD) analysis suggests that Si gets mostly dissolved into Fe after 80 h of milling for all compositions. The residual Si was found to form an intermetallic Fe₃Si. The dissolution was further confirmed from the field emission scanning electron microscopy/energy dispersive X-ray analysis (FE-SEM/EDX). With increased milling time, the lattice parameter and lattice strain are found to increase. However, the crystallite size decreases from micrometer (75–95 μm) to nanometer (10–20 nm). Mössbauer spectra analysis suggests the presence of essentially ferromagnetic phases with small percentage of super paramagnetic phase in the system. The saturation magnetization (M _s), remanance (M _r) and coercivity (H _c) values for Fe-0Mn sample after 120 h of milling were 96.4 Am²/kg, 11.5 Am²/kg and 12.42 k Am^?1, respectively. However, for Fe-10Mn-5Cu sample the M _s, H _c and M _r values were found to be 101.9 Am²/kg, 10.98 kA/m and 12.4 Am²/kg, respectively. The higher value of magnetization could be attributed to the favourable coupling between Mn and Cu.