Venus lower atmospheric composition: preliminary results from pioneer venus

Initial examination of data from the neutral mass spectrometer on the Pioneer Venus sounder probe indicates that the abundances of argon-36, argon-38, and neon-20 in the Venus atmosphere are much higher than those of the corresponding gases in Earth's atmosphere, although the abundance of radiogenic argon-40 is apparently similar for both planets. The lower atmosphere of Venus includes significant concentrations of various gaseous sulfur compounds. The inlet leak to the mass spectrometer was temporarily blocked by an apparently liquid component of the Venus clouds during passage through the dense cloud layer. Analysis of gases released during the evaporation of the droplets shows the presence of water vapor to some compound or compounds of sulfur.     

Imaging quasiparticle interference in Bi2Sr2CaCu2O8+delta

Scanning tunneling spectroscopy of the high-Tc superconductor Bi2Sr2CaCu2O8+delta reveals weak, incommensurate, spatial modulations in the tunneling conductance. Images of these energy-dependent modulations are Fourier analyzed to yield the dispersion of their wavevectors. Comparison of the dispersions with photoemission spectroscopy data indicates that quasiparticle interference, due to elastic scattering between characteristic regions of momentum-space, provides a consistent explanation for the conductance modulations, without appeal to another order parameter. These results refocus attention on quasiparticle scattering processes as potential explanations for other incommensurate phenomena in the cuprates. The momentum-resolved tunneling spectroscopy demonstrated here also provides a new technique with which to study quasiparticles in correlated materials.     

Welfare dependence within and across generations

A central question in the debate about the effects of welfare programs is whether their intended positive results--providing needed resources to recipients and their children--outweigh any unintended negative results--for example, the breaking up of families, reduction in work effort, or the fostering of a welfare "culture" that is passed on from parent to child. Recent research shows that although work effort is affected adversely by the generosity of welfare programs, effects on family structure appear quite weak, most welfare experiences are relatively short, and the majority of women who grew up in homes heavily dependent on welfare do not rely on those programs when they are young adults.     

Chemical Feeding Deterrent Mobilized in Response to Insect Herbivory and Counteradaptation by Epilachna tredecimnotata

Experimentally damaged leaves of Cucurbita moschata mobilize substances to the damaged region within 40 minutes. These substances stimulate feeding by Acalymma vittata (Coleoptera: Chrysomelidae) and inhibit feeding by Epilacha tredecimnotata (Coleoptera: Coccinelidae). Under natural conditions, Epilachna cuts a circular trench in the leaf before feeding on the encircled leaf material, thus preventing mobilization of the deterrent substances to the feeding area.     

Naturally acquired antibodies to sporozoites do not prevent malaria: vaccine development implications

The first human vaccines against the malaria parasite have been designed to elicit antibodies to the circumsporozoite protein of Plasmodium falciparum. However, it is not known whether any level of naturally acquired antibodies to the circumsporozoite protein can predict resistance to Plasmodium falciparum malaria. In this study, 83 adults in a malaria-endemic region of Kenya were tested for circumsporozoite antibodies and then treated for malaria. They were monitored for the development of new malaria infections for 98 days. Antibody levels, as determined by four assays in vitro, were indistinguishable between the 60 individuals who did and the 23 who did not develop parasitemia during follow-up, and there was no apparent relation between day of onset of parasitemia and level of antibodies to circumsporozoite protein. Unless immunization with sporozoite vaccines induces antibodies that are quantitatively or qualitatively superior to the circumsporozoite antibodies in these adults, it is unlikely that such antibodies will prevent infection in areas with as intense malaria transmission as western Kenya.