The magnetic field of saturn: pioneer 11 observations

The intrinsic magnetic field of Saturn measured by the high-field fluxgate magnetometer is much weaker than expected. An analysis of preliminary data combined with the preliminary trajectory yield a model for the main planetary field which is a simple centered dipole of moment 0.20 +/- 0.01 gauss-Rs(3) = 4.3 +/- 0.2 x 10(28) gauss-cm(3) (1 Rs = 1 Saturn radius = 60,000 km). The polarity is opposite that of Earth, and, surprisingly, the tilt is small, within 2 degrees +/- 1 degrees of the rotation axis. The equatorial field intensity at the cloud tops is 0.2 gauss, and the polar intensity is 0.56 gauss. The unique moon Titan is expected to be located within the magnetosheath of Saturn or the interplanetary medium about 50 percent of the time because the average subsolar point distance to the magnetosphere is estimated to be 20 Rs, the orbital distance to Titan.     

N-Cadherin, a cell adhesion molecule involved in establishment of embryonic left-right asymmetry

Within the bilaterally symmetric vertebrate body plan, many organs develop asymmetrically. Here, it is demonstrated that a cell adhesion molecule, N-cadherin, is one of the earliest proteins to be asymmetrically expressed in the chicken embryo and that its activity is required during gastrulation for proper establishment of the left-right axis. Blocking N-cadherin function randomizes heart looping and alters the expression of Snail and Pitx2, later components of the molecular cascade that regulate left-right asymmetry. However, the expression of other components of this cascade (Nodal and Lefty) was unchanged after blocking N-cadherin function, suggesting the existence of parallel pathways in the establishment of left-right morphogenesis. Here, the results suggest that N-cadherin-mediated cell adhesion events are required for establishment of left-right asymmetry.     

Transmission of vesicular stomatitis virus from infected to noninfected black flies co-feeding on nonviremic deer mice

Vesicular stomatitis is an economically important arboviral disease of livestock. Viremia is absent in infected mammalian hosts, and the mechanism by which insects become infected with the causative agents, vesicular stomatitis viruses, remains unknown. Because infected and noninfected insects potentially feed on the same host in nature, infected and noninfected black flies were allowed to feed on the same host. Viremia was not detected in the host after infection by a black fly bite, but because noninfected black flies acquired the virus while co-feeding on the same host with infected black flies, it is concluded that a viremic host is not necessary for an insect to be infected with the virus. Thus co-feeding is a mechanism of infection for an insect-transmitted virus.     

Nature and domestic life in the Valle del Cuñapirú (Misiones, Argentina): Reflections on Mbyá-Guaraní ethnoecology

Through the ethnographic record of the subsistence activities partially or completely performed in the domestic sphere in two Mbyá-Guaraní settlements in Misiones (Argentina), we outline factors important in describing the local natural environment. Data was collected through systematic observation and also through semi-structured interviews. Analysis indicates that the natural environment of the area is characterized by the indigenous community in several different ways. Thus, local people view the environment as made up of different “micro-environments,” and they consequently think of the elements that compose these “micro-environments” as having different, distinct characteristics. In the context of their daily activities, both these “micro-environments” and the elements that compose them are regarded as resources, in that they are viewed in terms of what is in them relevant to the subsistence of these groups in the rainforest. It is the intention of this study to initiate the systematic recording and processing of information on how these indigenous communities know and manage the natural resources available to them in their daily life.     

Pertussis toxin S1 mutant with reduced enzyme activity and a conserved protective epitope

Pertussis toxin (PTX) is a major virulence factor in whooping cough and can elicit protective antibodies. Amino acid residues 8 to 15 of PTX subunit S1 are important for the adenosine diphosphate-ribosyltransferase activity associated with the pathobiological effects of PTX. Furthermore, this region contains at least a portion of an epitope that elicits both toxin-neutralizing and protective antibody responses in mice. The gene encoding the S1 subunit was subjected to site-specific mutagenesis in this critical region. A mutant containing a single amino acid substitution (Arg9----Lys) had reduced enzymatic activity (approximately 0.02% of control) while retaining the protective epitope. This analog S1 molecule may provide the basis for a genetically detoxified PTX with potential for use as a component of an acellular vaccine against whooping cough.     

提高梅花鹿再生茸产量的研究

于１９９０年３月－６月分别在黑龙江省海林县三部落鹿和吉林省松花湖鹿场进行试验。用止血，提高动物营养和人工降雨增加鹿舍相对湿度的三种方法对梅花鹿再生茸生产生长的影响和潜力进行了研究。研究结果表明：单纯进行锯茸止血或提高动物营养对再生茸的产量没有明显影响（Ｐ＞０．０５）；在止血和提高动物营养的基础上同时进行人工降雨，可明显中再生茸的产量１７５±２８ｇ（Ｐ＜０．０１），使锯口愈合时间提前４．６±０．４ｄ     

Myoglobin diffusion in bovine heart muscle

The rotational mobility of myoglobin in situ was determined by proton nuclear magnetic resonance line width measurements of a characteristic myoglobin resonance observed in bovine heart muscle spectra. The protein diffuses intracellularly at nearly half the rate observed in dilute solution. This high mobility allows the oxygenated form of myoglobin to contribute significantly to the overall diffusive flux of oxygen in respiring heart muscle.     

农机液压系统油温过热的多例故障原因分析

该文通过对农机压系统油温过热的多例故障实际调查，总结分析了引起液压系统油温过热的各种原因，并相应提出了排除故障的方法及预防措施。     

Persistent increase in brain serotonin turnover after chronic administration of LSD in the rat

Lysergic acid diethylamide at doses of 20 micrograms per kilogram per day was administered orally to rats for I month. Eighteen hours after the final dose a 25 to 30 percent increase in the synthesis and turnover of serotonin was noted, as well as a moderate but significant increase in the concentration of tryptophan (18 percent) and serotonin (13 percent) in the brain.