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141.
The biodiversity sciences represent the disciplines of whole-organism biology, including systematics, ecology, population biology, behaviour and the fields of comparative biology. The biodiversity sciences are critically important to society because it is knowledge of whole-organisms that is essential for managing and conserving the world's species. Because of an acceleration in environmental degradation and global biodiversity loss in recent decades, the need for the biodiversity sciences has never been more urgent. Yet, biodiversity science is not well supported relative to other fields of science, and thus the need for knowledge about organisms and their environment is far outstripping biologists' ability to provide it. National and international capacity for biodiversity science must therefore be increased substantially. Each nation should establish a national biodiversity research programme coordinated across all government agencies. An international biodiversity research programme should also be established, perhaps with an organizational structure that parallels the International Geosphere-Biosphere Programme. Biodiversity scientists must assume a leadership role in educating the public and bringing about policy changes that will enhance our understanding of the world's species and their ecosystems.  相似文献   
142.
A behavior or strategy which is evolutionarily stable must be both optimal and stable. The strategy must be optimal in that it maximizes the expected fitness of all the individuals using it. In addition, the strategy must be resistant to invasion by a mutant. The difference between the Nash solution of game theory and the ESS used in ecology is that the Nash solution only satisfies an optimality criterion and not an evolutionary stability criterion. We extend the ESS definition of Maynard Smith and Price so that it can be applied directly to two-strategy evolutionary games. The concept of a balanced game is introduced, and necessary conditions are derived which are similar to the Nash necessary conditions. The balanced game necessary conditions may be used for direct calculation of ESS candidates. These results are used to examine the optimal flowering time of an annual plant experiencing competition from neighboring plants. The plant competition model is general, and the results may be applied to a wide range of interference competition problems.  相似文献   
143.
Vertigo or disequilibrium occurring in patients after concussive and nonconcussive head trauma may be due to a pathologic perilymphatic fistula from the inner ear through the oval and round window areas of the middle ear. Of 33 patients who had successful grafting of the fistulous area at middle ear exploration, 32 had resolution of vertigo, and 12 of 23 who had an associated hearing loss had improved hearing. Perilymphatic fistulas associated with vertigo and hearing loss after head trauma can be diagnosed with great certainty and are surgically curable in the great majority of cases. Patients with post-concussive syndrome, whose symptoms include vertigo or disequilibrium, should have a thorough otologic evaluation for the possibility of a perilymphatic fistula.  相似文献   
144.
We administered 45 Nd-YAG laser treatments in 29 patients (18 men) aged 39 to 82 years who had lung malignancy; 26 patients had primary non-oat cell lung cancer and three had metastatic airway malignancy. In all, 25 of the patients had been previously treated with combination(s) of surgical procedure, radiation therapy and chemotherapy. Indications for laser treatment included endobronchial airway obstruction with uncontrolled cough, hemoptysis, dyspnea or unresolved atelectasis-pneumonia. Of 15 patients with partially occluded tracheobronchial airway tumors, immediate palliative relief was achieved in 13 patients and lasted one to six months after a single treatment. In this group there was one postoperative death related to respiratory failure and two patients subsequently died of massive pulmonary hemorrhage. However, of 14 patients with totally obstructed airways, immediate palliative relief was achieved in only five patients and this lasted three weeks to three months after a single treatment. In this group there were two postoperative deaths related to progressive respiratory failure; in one case it was associated with endobronchial combustion of the fiberoptic bronchoscope. All three patients in both groups who died of respiratory failure were in acute respiratory distress and terminally ill before the procedure. These findings suggest that Nd-YAG laser therapy may be most beneficial in patients with partially rather than totally occluded airways due to lung malignancy.  相似文献   
145.
Six strains of a new species, Legionella sainthelensi, were isolated from freshwater in areas affected by the volcanic eruptions of Mt. St. Helens in the state of Washington. Strains of L. sainthelensi are culturally and biochemically similar to other legionellae. They grow on buffered charcoal yeast agar but not on media that lack cysteine. They are gram-negative, nonsporeforming, motile rods that are positive in reactions for catalase, oxidase, gelatin liquefaction, and beta-lactamase. They are negative in reactions for urease, hydrolysis of hippurate, reduction of nitrates, fermentation of glucose, and blue-white autofluorescence. Their cell wall fatty acid composition is qualitatively similar to those of other legionellae, with 50 to 62% branched-chain fatty acids. They contain the isobranched-chain 14- and 16-carbon acids and anteisobranched-chain 15- and 17-carbon acids and relatively large amounts of straight-chain 16-carbon acid. All strains of L. sainthelensi contain approximately equal amounts of ubiquinones Q9, Q10, Q11, and Q12, a pattern similar to those of Legionella bozemanii, Legionella dumoffi, and Legionella longbeachae. Serological cross-reactions were observed between L. sainthelensi, both serogroups of L. longbeachae, and Legionella oakridgensis. Three strains of L. sainthelensi were greater than 90% related by DNA hybridization. The type strain of L. sainthelensi, Mt. St. Helens 4, was 36% related to the type strain of L. longbeachae and 3 to 14% related to the other nine described Legionella species.  相似文献   
146.
Streptomycin retards the phenotypic maturation of chick myogenic cells   总被引:2,自引:0,他引:2  
Summary As part of an effort to optimize conditions required for the complete maturation of muscle cells in vitro, we have investigated the effects of the antibiotics penicillin, streptomycin, and Fungizone (amphotericin B) on the development of cultured chick embryo skeletal muscle. It is shown that even low dosages of streptomycin, but not penicillin or Fungizone, retard protein synthesis and accumulation in these cultures. Myosin accumulation was also reduced and the appearance of striations in fused cells was delayed in myotubes formed in medium containing streptomycin. Additional data suggest that this overall retardation of myogenesis is due to the influence of streptomycin on maturing myotubes rather than early proliferation and cell fusion. These results are discussed with regard to recent efforts to promote the full maturation of muscle cells grown in culture. This research was supported by National Institutes of Health Grant NS 155882 and a Task Force on Drug Development Research Contract from The Muscular Dystrophy Association.  相似文献   
147.
Six children were provided with long-term biofeedback and academic treatment for attention deficit disorders. Their symptoms were primarily specific learning disabilities, and, in some cases, there were varying degrees of hyperkinesis. The training consisted of two sessions per week for 10 to 27 months, with a gradual phase-out. Feedback was provided for either increasing 12-to 15-Hz SMR or 16- to 20-Hz beta activity. Inhibit circuits were employed for blocking the SMR or beta when either gross movement, excessive EMG, or theta (4–8 Hz) activity was present. Treatment also consisted of combining the biofeedback with academic training, including reading, arithmetic, and spatial tasks to improve their attention. All children increased SMR or beta and decreased slow EEG and EMG activity. Changes could be seen in their power spectra after training in terms of increased beta and decreased slow activity. All six children demonstrated considerable improvement in their schoolwork in terms of grades or achievement test scores. None of the children are currently on any medications for hyperkinetic behavior. The results indicate that EEG biofeedback training, if applied comprehensively, can be highly effective in helping to remediate children who are experiencing attention deficit disorders.The authors would like to thank Mr. Kevin Bianchini for his assistance in this study.  相似文献   
148.
Ultrasonic characteristics of frozen liver   总被引:5,自引:0,他引:5  
The recent development of new ultrasound probes has made real-time intraoperative monitoring of cryosurgery, and thermocouple placement a possibility. It is shown that frozen tissue and thermocouple needles have acoustic characteristics that enable them to be easily visualized by ultrasound examination. Further in vivo animal studies are needed to examine temperature characteristics of visualized cryolesions, to develop scanning techniques, and to correlate ultrasonic findings with histologic changes in tissue.  相似文献   
149.
Summary Cross-compatibility of species in section Arachis Krap. et Greg. nom. nud., and chromosome pairing and pollen fertility in their interspecific F1 hybrids were studied to further understand the phylogenetic relationships among these species. Except those with A. batizocoi Krap. et Greg. nom. nud., hybrids between diploid species have near normal bivalent frequency (9.1–9.8) and moderate to high pollen fertility (60–91%). Hybrids between A. batizocoi and other species have low bivalent frequency (5.2–6.9) and very low pollen fertility (3–7%). These results confirm the earlier separation of these species into two groups based on karyomorphology and Mahalanobis D2 calculated on arm ratios. These studies also provide a picture of relative affinities between A. batizocoi, the lone member of one cluster, and the other species, and among the rest of the species. They also indicate that the basic chromosome complement in the two groups of species is the same. Chromosome pairing in triploid hybrids, (A. hypogaea L. X diploid wild species), suggests that A. batizocoi is the closest diploid relative of A. hypogaea. It is closer to A. hypogaea subspecies fastigiata Waldron than to A. hypogaea subspecies hypogaea Krap. et. Rig. Other diploid species of the section Arachis are equidistant from A. hypogaea, and have the same genome which has strong homology to one of the genomes of A. hypogaea. Based on the present results, the two tetraploid species, A. monticola Krap. et Rig. and A. hypogaea can be recognised as two forms of the same species. Breeding implications have been discussed in the light of chromosome behaviour observed in hybrids of A. hypogaea X diploid species, and on the presumptions that A. hypogaea has an AABB genomic constitution, and that among the diploid species, the B genome is present in A. batizocoi while the A genome is common to the other diploid species of section Arachis.Submitted as Journal Article No. 328 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)  相似文献   
150.
Hyperthermia at either 41.5 or 45 degrees C with variable heating times to reduce cell survival up to three orders of magnitude did not decrease significantly cellular ATP content when measured either immediately or up to 7 hr after a heat treatment. Similarly, cellular ATP content was not significantly reduced with step-down heating, precooling prior to hyperthermia, or thermotolerance induction. The data suggest that heat-induced depletion of intracellular ATP content is not a critical factor in the thermal death of cells heated under normal culture conditions.  相似文献   
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