Accelerated convergence for a normal state layered superconductor’s transverse resistance expression,measured with strip contacts

The expression of the transverse resistance for an ohmic parallelepipedic layered conductor, measured with strip contacts, extended along its width, is a slowly convergent series. This series is reworked and transformed to the sum of an analytical part and an exponentially convergent series, which reduces considerably the number of terms needed for the numerical evaluation. In addition, an asymptotic formula is obtained, valid for Γ < 2, Γ is the effective anisotropy. This formula is used to determine the room temperature resistivity anisotropy of two small Γ layered superconductors, which are 2H–NbSe₂ and 2H–TaSe₂.     

Vibrational stability in turning thin-walled pipe by multicutter heads

Russian Engineering Research -     

Substantiation of flow charts for reverse-osmosis desalting with the ion-exchange softening of sea water and permeate

The article has considered flow charts for the preparation of make-up water of boilers of low, medium, and high pressure (9.8 MPa) from the sea water based on reverse-osmosis desalination. We have proved the possibility of deep Na-cationic softening of permeate by their own concentrates of the desalination stage. Reliable prevention of calcium deposits on membranes is achieved by acidulation of the waters of the Black Sea and Na-(Mg-Na)-zeolite softening process of the Caspian Sea waters also with the use of the concentrate for regeneration of the cation-exchanger.     

Natural and human forcing in recent geomorphic change; case studies in the Rio de la Plata basin

An analysis of geomorphic system's response to change in human and natural drivers in some areas within the Río de la Plata basin is presented. The aim is to determine whether an acceleration of geomorphic processes has taken place in recent years and, if so, to what extent it is due to natural (climate) or human (land-use) drivers. Study areas of different size, socio-economic and geomorphic conditions have been selected: the Río de la Plata estuary and three sub-basins within its watershed. Sediment cores were extracted and dated (²¹⁰Pb) to determine sedimentation rates since the end of the 19th century. Rates were compared with time series on rainfall as well as human drivers such as population, GDP, livestock load, crop area, energy consumption or cement consumption, all of them related to human capacity to disturb land surface. Data on river discharge were also gathered. Results obtained indicate that sedimentation rates during the last century have remained essentially constant in a remote Andean basin, whereas they show important increases in the other two, particularly one located by the São Paulo metropolitan area. Rates in the estuary are somewhere in between. It appears that there is an intensification of denudation/sedimentation processes within the basin.Rainfall remained stable or varied very slightly during the period analysed and does not seem to explain increases of sedimentation rates observed. Human drivers, particularly those more directly related to capacity to disturb land surface (GDP, energy or cement consumption) show variations that suggest human forcing is a more likely explanation for the observed change in geomorphic processes. It appears that a marked increase in denudation, of a “technological” nature, is taking place in this basin and leading to an acceleration of sediment supply. This is coherent with similar increases observed in other regions.     

WHAT IS “URBAN STUDIES”? CONTEXT,INTERNAL STRUCTURE,AND CONTENT

ABSTRACT: The record of learned concern with cities is nearly as old as the city itself. In the past several decades, however, a distinct academic field of “Urban Studies” has emerged. This article characterizes the context, internal structure, and content of the field through interviews with leading scholars, probabilistic multidimensional scaling analyses of survey data, and a content analysis of a leading journal. The article concludes that although Urban Studies is in some respects not a bounded “academic discipline,” it is an intellectually coherent, distinctively structured, and promising field of inquiry steered by complex, ever‐changing, and often‐large‐scale realities and real‐world problems of evolving human settlements.     

Modern computerized automation systems for thermal power engineering and prospects for their future development

The possibility of using the Ethernet network as a network for the lower (controller) level of a computerized automation system is considered. A new term “distributed (multicore) control environment” is introduced. The architecture of an Ethernet-based distributed control environment is described and an example of its implementation in the Tornado-N computerized automation system is given.     

Relaxed multiple routing configurations: IP fast reroute for single and correlated failures

Multi-topology routing is an increasingly popular IP network management concept that allows transport of different traffic types over disjoint network paths. The concept is of particular interest for implementation of IP fast reroute (IP FRR). The authors have previously proposed an IP FRR scheme based on multi-topology routing called Multiple Routing Configurations (MRC). MRC supports guaranteed, instantaneous recovery from any single link or node failure in biconnected networks as well as from many combined failures, provided sufficient bandwidth on the surviving links. Furthermore, in MRC different failures result in routing over different network topologies, which gives a good control of the traffic distribution in the networks after a failure     

The start gene CDC28 and the genetic stability of yeast

The cdc28-srm mutation in Saccharomyces cerevisiae decreases spontaneous and induced mitochondrial rho- mutability and the mitotic stability of native chromosomes and recombinant circular minichromosomes. The effects of cdc28-srm on the genetic stability of cells support the hypothesis that links cell cycle regulation in yeast to changes in chromatin organization dependent on the start gene CDC28 (Hayles and Nurse, 1986).     

Ability of bovine mammary macrophages to enhance proliferation of autologous blood and mammary secretion lymphocytes

Cells were obtained by centrifuging the mammary secretion of healthy udders of 19 cows during the dry-period and during mid-lactation. The suspended cells were incubated in plastic wells. Those adhered cells classified as mammary macrophages were incubated with pokeweed mitogen (PWM). Autologous peripheral blood lymphocytes were added to wells containing untreated macrophage cultures or cultures pretreated with PWM. In seven cows autologous dry-period mammary lymphocytes were added instead of blood lymphocytes. The macrophages + lymphocyte cultures were subjected to the lymphocyte stimulation test (LST). For comparison, peripheral blood lymphocytes and dry-period secretion lymphocytes were also subjected to the LST in the presence of PWM. In all cases, mitogenic responses were higher in pretreated macrophage cultures than in background control cultures. The stimulation indices (SI) showed that PWM-pretreated dry-period mammary macrophages enhanced the proliferation of autologous peripheral blood lymphocytes to a greater extent than did blood lymphocytes plus PWM (49 +/- 10 v. 30 +/- 6; P less than or equal to 0.05). Mammary macrophages taken from the same cows but during midlactation also clearly induced proliferation of autologous peripheral blood lymphocytes but to a lesser extent than dry-period macrophages (16 +/- 2 v. 49 +/- 10; 16 +/- 2 v. 30 +/- 6; P less than or equal to 0.01 and P less than or equal to 0.05). The PWM pretreatment of mammary macrophages increased the proliferation of autologous dry-period mammary lymphocytes by at least a factor of three (28 +/- 8 v. 8 +/- 2 P less than or equal to 0.05). The present results indicate that bovine mammary macrophages pretreated with PWM enhance proliferation as well as modulation of mammary and peripheral blood lymphocytes. The modulation of lymphocyte stimulation as demonstrated here in vitro, has great significance regarding aspects of local immunostimulation related to modern treatment of mastitis.     

The vitamin D allowance of premature infants and their phosphorus-calcium metabolic status with different types of feeding and rickets prevention

The content of 25-hydroxycholecalciferol, calcium and phosphorus in blood serum was measured in 80 premature infants aged 12 to 120 days depending on the type of feeding and rickets prevention. Administration of vitamin D in a dose of 400 IU and increase of calcium consumption up to 110-120 mg and of phosphorus to 45-57 mg per kg body weight at the expense of calcinated cottage introduction into the diet provide for the optimal levels of 25-hydroxycholecalciferol and calcium in the blood of these children. Administration of calcium and phosphorus to children receiving breast feeding in doses of 80-90 and 33-37 mg/kg, respectively, is not sufficient for the maintenance of calcium homeostasis and endogenous supply with vitamin D even if the latter is given prophylactically. When children are fed with the mixture Maliutka, the maximal permissible dose of vitamin D may amount to 800 IU a day. Administration of vitamin D in a dose of 3750 IU is fraught with a danger of hypervitaminosis D in the presence of high alimentary supply with calcium and phosphorus and does not make calcium homeostasis return to normal in the presence of low supply with these mineral substances.