基于RS485的低压配电管理软件的设计

介绍了基于MAX49l的RS485接口和基于VB6．0的低压配电管理系统的设计。通过RS485通讯网络，主机可以对多个低压配电智能单冗进行远程控制、参数修改，有故障显示等功能。     

A simple algorithm for localized construction of non‐matching structural interfaces

A simple and effective algorithm for the modular construction of non‐matched interfaces is presented for the partitioned solution of large‐scale structural problems. The formulation is based on a recently developed four‐field variational principle, which introduces a connection frame between the interfaced partitions. A key result of the present study is a frame nodal placement criterion that uniquely determines the frame discretization into piecewise linear elements so that the interface patch test condition is satisfied a priori. The method is demonstrated with several 2D and 3D example problems. Copyright © 2002 John Wiley & Sons, Ltd.     

Cellular response to calcium phosphate ceramics implanted in rabbit bone

Two hydroxyapatite ceramics, synthesized by sintering from bovine bone and from a mixture of phosphate tricalcium and natural hydroxyapatite, were implanted in bone sites in rabbits. From day 7 after implantation, osteoblast-like cells were visible with thin layers of new bone on both biomaterials. Histomorphometry showed progressive increase in volume and surface of newly formed bone. Signs of cell-dependent resorption were visible at the surface of biomaterials and newly formed bone. There was a progressive decrease in relative volume and trabecular thickness of the biomaterials. Resorption of biomaterials appears to involve two cell types: multinucleated giant cells and osteoclast-like cells. The multinucleated giant cells observed had neither tartrate resistant acid phosphatase activity (TRAP) nor a ruffled border. Vesicles and vacuoles containing crystals observed in these cells suggest phagocytosis of biomaterials. The number of these cells decreased after day 14 following implantation. The osteoclast-like cells were TRAP positive. The structured modification and the TRAP activity demonstrated in the subjacent biomaterial suggest that the dissolution of the implant may be associated to an extracellular enzymatic activity of these cells. Electron microscopy revealed a clear zone and cytoplasmic membrane infolding in these cells, suggesting a ruffled border differentiation. The number of these cells increased with delay after implantation. It was concluded that the implantation of calcium phosphate ceramics in bone leads to new bone formation as well as to resorption of the biomaterials. The mechanism of resorption appears to associate crystal endocytosis by multinucleated giant cells and more classical resorption by osteoclast-like cells.     

Force direction and physical load in dynamic pushing and pulling

In pushing and pulling wheeled carts, the direction of force exertion may, beside the force magnitude, considerably affect musculoskeletal loading. This paper describes how force direction changes as handle height and force level change, and the effects this has on the loads on the shoulder and low back. Eight subjects pushed against or pulled on a stationary bar or movable cart at various handle heights and horizontal force levels while walking on a treadmill. The forces at the hands in the vertical and horizontal direction were measured by a force-transducer. The forces, body movements and anthropometric data were used to calculate the net joint torques in the sagittal plane in the shoulder and the lumbosacral joint. The magnitudes and directions of forces did not differ between the cart and the bar pushing and pulling. Force direction was affected by the horizontal force level and handle height. As handle height and horizontal force level increased, the pushing force direction changed from 45 degrees (SD 3.3 degrees) downward to near horizontal, while the pulling force direction changed from pulling upward by 14 degrees (SD 15.3 degrees) to near horizontal. As a result, it was found that across conditions the changes in force exertion were frequently reflected in changes in shoulder torque and low back torque although of a much smaller magnitude. Therefore, an accurate evaluation of musculoskeletal loads in pushing and pulling requires, besides a knowledge of the force magnitude, knowledge of the direction of force exertion with respect to the body.     

Study of circulating 25 hydroxyvitamin D

The levels of circulating 25 OH-D were determined by a direct radio-competition methods both in normal subjects and in subjects with various pathological conditions. In normal subjects, the average level of 25 OH-D was higher in summer (42.3 ng/ml) than in winter (29.1 ng/ml), P less than 0.005. Monthly variations in the 25 HO-D levels were found in relation to insolation The level of 25 OH-D was practically normal in osteoporosis (28.9 ng/ml), clearly lower in the mixed forms called "osteoporomalacia" (13.5 ng/ml, P less than 0.005) and very low in osteomalacia (5.8 ng/ml, P less than 0.001). In cases of cortisone osteopathy the average level was 22.8 ng/ml (NS). The level of 25 OH-D was also found to be lower in hepatic cirrhosis (11.7 ng/ml, P less than 0.01), in subjects treated with anticonvulsants (P less than 0.01), and in the course of hyperparathyroidism (P less than 0.002). There was no corelation between the level of 25 OH-D and calcaemia, phosphoraemia, circulating immunoreactive parathyroid hormone, or the relative osteoid volume. In contrast, there seemed to be a good correlation with the level of alkaline phosphatasaemia. The level of 25 OH-D was also determined in 4 subjects with vitamin-resistant osteomalacia: in 3 cases hepatic hydroxylation seemed normal, indicating the possibility of a subsequent disorder of vitamin D metabolism; in one case the absence of hepatic hydroxylation was noted.     

Effect of methylmercuric chloride on gangliosides of mouse neuroblastoma cells in culture

The effect of methylmercuric chloride (CH3HgCl) on the levels of gangliosides in mouse neuroblastoma cells (NBP2) in culture was studied. The treatment of NB cells with low concentrations (0.1 microM and 0.2 microM) of CH3HgCl, which did not affect the growth rate or morphology, caused an increase in the level of the GM3 ganglioside without changing the level of other gangliosides. The treatment of NB cells with higher concentrations (0.5 microM and 1 microM) of CH3HgCl, which inhibited the growth of NB cells, caused a decrease in the level of GM3 and an increase in the level of GM2. These results show that alterations in the levels of specific gangliosides can be observed in cells which do not exhibit any detectable change in growth rate or morphology. This change may be associated with subtle changes in brain functions, including behavioral and psychological changes, after exposure to low concentrations of organic mercury.     

Differential effect of ebselen on compound 48/80- and anti-IgE-induced histamine release from rat peritoneal mast cells

A 77-year-old artist having endocapsular phacoemulsification surgery and intraocular lens implantation illustrated her visual impressions of the procedure in 6 stages, from draping to lens implantation. Her illustrations and commentary indicate that she experienced clear visualization of instruments and colorful abstract imagery. These paintings were shown to 30 consecutive patients to assess their usefulness in preoperatively informing and preparing patients for surgery. With the widespread use of local and topical anesthesia, it is pertinent to the ophthalmic surgeon to understand what patients may seen when vision is retained during the procedure.     

Potential Relationship between Inadequate Response to DNA Damage and Development of Myelodysplastic Syndrome

Hematopoietic stem cells (HSCs) are responsible for the continuous regeneration of all types of blood cells, including themselves. To ensure the functional and genomic integrity of blood tissue, a network of regulatory pathways tightly controls the proliferative status of HSCs. Nevertheless, normal HSC aging is associated with a noticeable decline in regenerative potential and possible changes in other functions. Myelodysplastic syndrome (MDS) is an age-associated hematopoietic malignancy, characterized by abnormal blood cell maturation and a high propensity for leukemic transformation. It is furthermore thought to originate in a HSC and to be associated with the accrual of multiple genetic and epigenetic aberrations. This raises the question whether MDS is, in part, related to an inability to adequately cope with DNA damage. Here we discuss the various components of the cellular response to DNA damage. For each component, we evaluate related studies that may shed light on a potential relationship between MDS development and aberrant DNA damage response/repair.     

A contact formulation based on localized Lagrange multipliers: formulation and application to two‐dimensional problems

The non‐penetration condition in contact problems is traditionally based on the classical Lagrange multiplier method. This method makes extensive use of modelling details of the contacting bodies for contact enforcement as the contact surface meshes are in general non‐matching. To deal with this problem we introduce a novel element in the Lagrange multiplier approach of contact modelling, namely, a contact frame placed in between contacting bodies. It acts as a medium through which contact forces are transferred without violating equilibrium in the contact domain for discrete contact models. Only nodal information of the contacting bodies is required which makes the proposed contact enforcement generic. The contact frame has its own independent freedoms, which allows the formulation to pass contact patch tests by design. Copyright © 2002 John Wiley & Sons, Ltd.