Immunoreactivity of Brazilian HIV isolates with different V3 motifs

The influence of noncompetitive (MK-801), competitive (AP-7) and the antagonist of polyamines site of NMDA receptor (arcaine) on the central activity of angiotensin II (A II) was studied. The open field test, conditioning of active avoidance responses (CARs) and passive avoidance situation was used to investigate learning and memory in rats. All used antagonists decreased beneficial action of A II on these processes.     

Attractive and inhibitory pheromones produced in the bark beetle,Dendroctonus brevicomis,during host colonization: Regulation of inter- and intraspecific competition

Quantities of attractive (exo-brevicomin and frontalin) and inhibitory (trans-verbenol, verbenone, and ipsdienol) pheromones were monitored in both sexes ofDendroctonus brevicomis during their colonization of a ponderosa pine. Verbenone was found in males in the greatest amounts at the time of landing, and it declined more rapidly than the other pheromones in either sex. The amounts of frontalin andexo-brevicomin in males and females, respectively, increased after initial boring within the host but began to decline after mating. The quantity oftrans-verbenol in both sexes (females had significantly more) declined more gradually thanexo-brevicomin, frontalin, and verbenone. Ipsdienol was found only in males during the initial stages of attack when encountering the resin. It is suggested that along with a general decline in all pheromonal components, a sufficient change in the ratio of the attractive pheromones to an inhibitory pheromone,trans-verbenol, may play a role in termination of aggregation.trans-Verbenol may also function along with verbenone and ipsdienol in limiting the density of attack and thus intraspecific competition. These inhibitory pheromones also appear to cause several competing species of bark beetle to avoid landing in areas infested withD. brevicomis, even when their own pheromone is present.Coleoptera:Scolytidae. These studies were supported in part by the Rockefeller Foundation, USDA Forest Service, Regional research project W-110, SEA/ USDA, and the National Science Foundation and Environmental Protection Agency through a grant (NSF GB-34719/BMS 75-04223) to the University of California.     

An economical synthesis of the major sex attractant of the oak leaf roller—cis-10-tetradecenyl acetate

The major sex attractant of the oak leaf roller (Archips semiferanus Walker),cis-10-tetradecenyl acetate (I), was synthesized in 55–62% overall yield by a highly economical route from inexpensive azelaic acid (II).Authorized as Paper No. 4779 in the Journal Series of the Pennsylvania Agricultural Experiment Station.     

Sustainable Disposal of Domestic Sanitary Waste

The study presented is an example of the assessment of the relative sustainability of either option for disposal of domestic sanitary waste, either via the toilet or via the solid waste route. This required an evaluation of the total (social, economic, environmental, and technical) benefit/cost of implementing and adopting the alternative routes and an assessment of public responsiveness to encouragement to change sanitary waste disposal practices. It illustrates how, even for an apparently straightforward either/or question, the assessment of relative sustainability is complex and the amount of data needed to quantify sustainability indicators is prodigious. The study also provides an appraisal of the effectiveness of public campaigns to reduce waterborne disposal. Important information regarding public attitude and behavior in relation to wastewater systems has been acquired and lessons for ways of encouraging behavioral change to more sustainable ways of living have been gleaned.     

Studies on spinel cobaltites,MCo2O4 (M = Mn,Zn, Fe,Ni and Co) and their functional properties

Optimization of electrodes for charge storage with appropriate processing conditions places significant challenges in the developments for high performance charge storage devices. In this article, metal cobaltite spinels of formula MCo₂O₄ (where M = Mn, Zn, Fe, Ni and Co) are synthesized by oxalate decomposition method followed by calcination at three typical temperatures, viz. 350, 550, and 750 °C and examined their performance variation when used as anodes in lithium ion batteries. Phase and structure of the materials are studied by powder x-ray diffraction (XRD) technique. Single phase MnCo2O4,ZnCo2O4 and Co3O4 are obtained for all different temperatures 350 °C, 550 °C and 750 °C; whereas FeCo₂O₄ and NiCo₂O₄ contained their constituent binary phases even after repeated calcination. Morphologies of the materials are studied via scanning electron microscopy (SEM): needle-shaped particles of MnCo₂O₄ and ZnCo₂O₄, submicron sized particles of FeCo₂O₄ and agglomerated submicron particle of NiCo₂O₄ are observed. Galvanostatic cycling has been conducted in the voltage range 0.005–3.0 V vs. Li at a current density of 60 mA g^?1 up to 50 cycles to study their Li storage capabilities. Highest observed charge capacities are: MnCo₂O₄ – 365 mA h g^?1 (750 °C); ZnCo₂O₄ – 516 mA h g^?1 (550 °C); FeCo₂O₄ – 480 mA h g^?1 (550 °C); NiCo₂O₄ – 384 mA h g^?1 (750 °C); and Co₃O₄ – 675 mA h g^?1 (350 °C). The Co₃O₄ showed the highest reversible capacity of 675 mA h g^?1; the NiO present in NiCo₂O₄ acts as a buffer layer that results in improved cycling stability; the ZnCo₂O₄ with long needle-like shows good cycling stability.     

Computationally intensive econometrics using a distributed matrix-programming language

This paper reviews the need for powerful computing facilities in econometrics, focusing on concrete problems which arise in financial economics and in macroeconomics. We argue that the profession is being held back by the lack of easy-to-use generic software which is able to exploit the availability of cheap clusters of distributed computers. Our response is to extend, in a number of directions, the well-known matrix-programming interpreted language Ox developed by the first author. We note three possible levels of extensions: (i) Ox with parallelization explicit in the Ox code; (ii) Ox with a parallelized run-time library; and (iii) Ox with a parallelized interpreter. This paper studies and implements the first case, emphasizing the need for deterministic computing in science. We give examples in the context of financial economics and time-series modelling.     

Synthesis and distribution of cytokeratins in healthy and ulcerated bovine claw epidermis

Keratinization of the epidermal cells of the bovine claw generates the horn that gives the tissue its mechanical strength. Disruption of keratinization is likely to have a detrimental effect on the strength and integrity of the horn, and could lead to solar lesions and lameness. As part of a wider investigation of the cell biological causes of lameness in dairy animals, we have compared keratin synthesis and distribution in healthy bovine claw tissue with those in hooves with solar ulcers. Protein synthesis was measured by [35S]-labelled amino acid incorporation in claw tissue explant cultures. [35S]-labelled protein synthesis was higher in tissue from diseased claws than in healthy claws, and highest at the ulcer site. The identity of proteins synthesised in vitro did not differ between healthy and diseased tissue. DNA synthesis indicative of cell proliferation was also elevated in diseased tissue. Immunoblotting after one- or two-dimensional electrophoresis showed cytokeratins (CK) 4, 5/6, 10 and 14 to be amongst those expressed in healthy claw tissue. The relative abundance of these keratins was not altered in healthy regions of ulcerated hooves, nor at the ulcer site, but CK16, not usually found in healthy tissue, was detected in the sole of diseased claws. CK5/6 and CK14 were shown by immunohistochemistry to be present in the basal epidermis of healthy tissue, whereas CK10 was found in supra-basal layers. In healthy tissue from ulcerated claws, this distribution was unaltered, but at the site of solar ulcers, CK5/6 and CK14 were each found in both basal and supra-basal epidermis. The study suggests that solar ulceration of the bovine claw is not associated with gross alteration in the keratin composition of the tissue, but causes abnormal distribution of cytokeratins, perhaps as a result of loss of positional cues from the basement membrane. Ulceration did, however, stimulate cell repair involving epidermal protein synthesis (including keratins), and keratinocyte proliferation.     

Expansion of Liquid 4He Through the Lambda Transition

Zurek suggestedNature 317 , 505; 1985) that the Kibble mechanism, through which topological defects such as cosmic strings are believed to have been created in the early Universe, can also result in the formation of topological defects in liquid ⁴ He, i.e. quantised vortices, during rapid quenches through the superfluid transition. Preliminary experiments (Hendry et al., Nature 368 , 315; 1994) seemed to support this idea in that the quenches produced the predicted high vortex-densities. The present paper describes a new experiment incorporating a redesigned expansion cell that minimises vortex creation arising from conventional hydrodynamic flow. The post-quench line-densities of vorticity produced by the new cell are no more than 10 ¹⁰ m ^–2 , a value that is at least two orders of magnitude less than the theoretical prediction. We conclude that most of the vortices detected in the original experiment must have been created through conventional flow processes.     

Quantum Turbulence in 4He, Oscillating Grids, and Where Do We Go Next?

Experimental approaches to the study of quantum turbulence (QT) in superfluid ⁴He in the low temperature limit, where the normal fluid density is effectively zero, are considered. A succinct general introduction covers liquid ⁴He, superfluidity, critical velocities for the onset of dissipation, quantized vortex lines and QT. The QT can be created mechanically by the oscillation of wires or grids above characteristic critical velocities. The interesting dynamics of the oscillating grid are discussed. It exhibits an enhanced effective mass due to backflow, as expected from classical hydrodynamics. It is found that the critical velocity attributable to the onset of QT production rises with increasing temperature. Oscillating objects like grids or wires create QT that is not well-characterized in terms of length scale, and the QT is not spatially homogeneous. The QT can be detected by the trapping of negative ions on vortex cores. Although the corresponding capture cross-section has not yet been measured, it is evidently very small, so that the technique cannot be expected to be a very sensitive one. In the future it is hoped to create well-characterized, homogeneous QT by means of a drawn grid. Improved sensitivity in the detection of QT is being sought through calorimetric techniques that monitor the temperature rise of the liquid caused by the decay of the vortex lines.