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91.
Keith Shaw 《西北部美国博物学家》2011,41(3)
An unusual wear pattern in the cheek teeth of elk-wapiti, in which the third premolars and first molars of the upper jaw wear excessively into corresponding teeth in the lower jaw, was found in a Glacier National Park, Montana, elk skull. This unusual wear pattern was previously reported from elk of the Yellowstone-Jackson, Wyoming, herd. 相似文献
92.
Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Quadrat and propagule trapping studies were made on the moraine of the Schoolroom Glacier and in adjacent dry alpine meadow vegetation in the Teton Range in 1978–1979. Forty-six species of vascular plants were collected. Distributionally, three groups of species exist. One of these is concentrated primarily on the moraine, a second in the meadow, and the third in a narrow ecotonal band at the base of the distal slope of the moraine. The moraine slopes are steep and unstable, with vegetation cover ranging from 1 to 9 percent, dominated by Cirsium tweedyi (Rydb.) Petr. Along the more stable moraine crest the vegetation cover is heavier, and is similar to that in the meadow. The meadow vegetation cover is about 50 percent, dominated by Astragalus kentrophyta Gray. Using a combination of cover and frequency as a measure of importance, dominance-diversity curves were constructed for the moraine and meadow. Both approach geometric series, which are suggested as indicating harsh environments. Abiotically pollinated species are more successful on the moraine than biotically pollinated species, but the reverse is true for the meadow. Propagule trapping studies suggest that dispersal of anemochorous propagules onto the moraine is very low compared with dispersal in the meadow. 相似文献
93.
Familial dementia caused by polymerization of mutant neuroserpin. 总被引:13,自引:0,他引:13
R L Davis A E Shrimpton P D Holohan C Bradshaw D Feiglin G H Collins P Sonderegger J Kinter L M Becker F Lacbawan D Krasnewich M Muenke D A Lawrence M S Yerby C M Shaw B Gooptu P R Elliott J T Finch R W Carrell D A Lomas 《Nature》1999,401(6751):376-379
Aberrant protein processing with tissue deposition is associated with many common neurodegenerative disorders; however, the complex interplay of genetic and environmental factors has made it difficult to decipher the sequence of events linking protein aggregation with clinical disease. Substantial progress has been made toward understanding the pathophysiology of prototypical conformational diseases and protein polymerization in the superfamily of serine proteinase inhibitors (serpins). Here we describe a new disease, familial encephalopathy with neuroserpin inclusion bodies, characterized clinically as an autosomal dominantly inherited dementia, histologically by unique neuronal inclusion bodies and biochemically by polymers of the neuron-specific serpin, neuroserpin. We report the cosegregation of point mutations in the neuroserpin gene (PI12) with the disease in two families. The significance of one mutation, S49P, is evident from its homology to a previously described serpin mutations, whereas that of the other, S52R, is predicted by modelling of the serpin template. Our findings provide a molecular mechanism for a familial dementia and imply that inhibitors of protein polymerization may be effective therapies for this disorder and perhaps for other more common neurodegenerative diseases. 相似文献
94.
95.
Keith R. Shaw 《西北部美国博物学家》2011,38(1)
The plant previously reported from Alberta as Canada Plum ( Prunus nigra Ait. ) flowered and is now recognized European Buckthorn ( Rhamnus cathartica L.). 相似文献
96.
Coursework Masters degrees that are offered as block release programmes provide opportunities for access to postgraduate education for adult students while in full time employ. These students attend structured contact modules after which they return to home and work and a distance format of study. However, these courses are generally characterised by low completion rates and lengthy time to completion, particularly of the research dissertation. While various explanations for this problem have been offered, for example, students’ non-academic commitments and supervisor–student-relations, our particular concern in this paper is students’ reading and writing practices in the transition from professional work practice and Masters coursework to the research dissertation. This paper proposes a systemic design to improve student reading and writing in this transition, and the proposal is illustrated using a block release coursework Masters programme in Management at a South African university. The design draws on interpretive systems ideas to think about the different levels of institutional and disciplinary context that impact on the research dissertation. We also use an academic literacies perspective—the concepts of literacy practice, language identity and power in particular—to think about reading and writing. This design incorporates components that include system elements, relationships, purpose and feedback that facilitate interaction between the conventions of the research practice, what the student brings to the practice, and the agency of the student. 相似文献
97.
Many studies have assessed genetic changes in exotic plant species in their native and introduced ranges, but none have focused on genetic variation in native plant species in response to exotic invasion. We examine characteristics of native plant communities within and outside old (> 25 year) invasions of Acroptilon repens (Russian knapweed) and Cardaria draba (hoary cress). We also document genetic variability of 4 native grass populations ( Hesperostipa comata [needle and thread], Achnatherum hymenoides [Indian ricegrass], Sporobolus airoides [alkali sacaton], and Poa secunda [Sandberg bluegrass]) from 2 areas: adjacent to and within weed invasions. Native plant species richness and diversity did not differ between invaded and noninvaded areas. Inter-simple sequence repeat (ISSR) analysis of individual native perennial grasses of each of the 4 species suggests that populations exposed to long-term coexistence with exotics may differ from adjacent noninvaded populations. We suggest that future research efforts should focus on intraspecific diversity of native plant species to identify possible candidates for restoration following weed control. 相似文献
98.
Tildesley MJ Savill NJ Shaw DJ Deardon R Brooks SP Woolhouse ME Grenfell BT Keeling MJ 《Nature》2006,440(7080):83-86
Foot-and-mouth disease (FMD) in the UK provides an ideal opportunity to explore optimal control measures for an infectious disease. The presence of fine-scale spatio-temporal data for the 2001 epidemic has allowed the development of epidemiological models that are more accurate than those generally created for other epidemics and provide the opportunity to explore a variety of alternative control measures. Vaccination was not used during the 2001 epidemic; however, the recent DEFRA (Department for Environment Food and Rural Affairs) contingency plan details how reactive vaccination would be considered in future. Here, using the data from the 2001 epidemic, we consider the optimal deployment of limited vaccination capacity in a complex heterogeneous environment. We use a model of FMD spread to investigate the optimal deployment of reactive ring vaccination of cattle constrained by logistical resources. The predicted optimal ring size is highly dependent upon logistical constraints but is more robust to epidemiological parameters. Other ways of targeting reactive vaccination can significantly reduce the epidemic size; in particular, ignoring the order in which infections are reported and vaccinating those farms closest to any previously reported case can substantially reduce the epidemic. This strategy has the advantage that it rapidly targets new foci of infection and that determining an optimal ring size is unnecessary. 相似文献
99.
Shaw P Greenstein D Lerch J Clasen L Lenroot R Gogtay N Evans A Rapoport J Giedd J 《Nature》2006,440(7084):676-679
Children who are adept at any one of the three academic 'R's (reading, writing and arithmetic) tend to be good at the others, and grow into adults who are similarly skilled at diverse intellectually demanding activities. Determining the neuroanatomical correlates of this relatively stable individual trait of general intelligence has proved difficult, particularly in the rapidly developing brains of children and adolescents. Here we demonstrate that the trajectory of change in the thickness of the cerebral cortex, rather than cortical thickness itself, is most closely related to level of intelligence. Using a longitudinal design, we find a marked developmental shift from a predominantly negative correlation between intelligence and cortical thickness in early childhood to a positive correlation in late childhood and beyond. Additionally, level of intelligence is associated with the trajectory of cortical development, primarily in frontal regions implicated in the maturation of intelligent activity. More intelligent children demonstrate a particularly plastic cortex, with an initial accelerated and prolonged phase of cortical increase, which yields to equally vigorous cortical thinning by early adolescence. This study indicates that the neuroanatomical expression of intelligence in children is dynamic. 相似文献
100.