DSK1, a novel kinesin-related protein from the diatom Cylindrotheca fusiformis that is involved in anaphase spindle elongation.

We have identified an 80-kD protein that is involved in mitotic spindle elongation in the diatom Cylindrotheca fusiformis. DSK1 (Diatom Spindle Kinesin 1) was isolated using a peptide antibody raised against a conserved region in the motor domain of the kinesin superfamily. By sequence homology, DSK1 belongs to the central motor family of kinesin-related proteins. Immunoblots using an antibody raised against a non-conserved region of DSK1 show that DSK1 is greatly enriched in mitotic spindle preparations. Anti-DSK1 stains in diatom central spindle with a bias toward the midzone, and staining is retained in the spindle midzone during spindle elongation in vitro. Furthermore, preincubation with anti-DSK1 blocks function in an in vitro spindle elongation assay. This inhibition of spindle elongation can be rescued by preincubating concurrently with the fusion protein against which anti-DSK1 was raised. We conclude that DSK1 is involved in spindle elongation and is likely to be responsible for pushing hal-spindles apart in the spindle midzone

Frequency and Characteristics of Arctic Tundra Fires

Characteristics of over 50 tundra fires, located primarily in the western Arctic, are summarized. In general, only recent records were available and the numbers of fires were closely related to the accessibility of the area. Most of them covered areas of less than one square kilometre (in contrast to forest fires which are frequently larger) but three tundra fires on the Seward Peninsula of Alaska burned, in aggregate, 16,000 square kilometres of cottongrass tussocks. Though tundra fires can occur as early as May, most of them break out in July and early August. Biomass decreases, and so fires are more easily stopped by discontinuities in vegetation, with distance northward

Northern Research Legacies and the Future: A University Perspective

I am writing as a Canadian who was involved in northern research as a post-doctoral student in the 1970s and who, since then, has been involved as a researcher and educator in southern university-based northern studies. My goal is to bring together some comments on research databases and the lost generation of northern researchers, .... The North and Northerners have always faced major changes; in the 20th century, these included the air industry, the DEW Line, hydroelectric dams, mines and roads. Now Northerners are facing the greatest acceleration of changes on landscapes and in communities since the 1970s. On landscapes remote from communities is a diamond industry that could supply the world with 15% of its diamonds within three years; several thousand people will be employed. Petroleum exploration (seismic and drilling) is operating today at the highest level since the 1970s. Pipeline construction projects of a size greater than ever seen in North America are being proposed: the "Texas of the North" is the new vision. ... What are the research needs? Researchers are being urged to collect more and better data and to make better predictions. They are urged to adhere to ethics guidelines, to demonstrate the impacts of their research at the proposal stage, and to effectively transmit research results to the community. Those responsible for management policy and implementation in the North are now searching for solutions, and they are finding many gaps in our knowledge. They emphasize that data are obsolete and capacity building is needed. ... Questions are being asked about jobs for university researchers who work on northern topics: are there opportunities for long-term employment, or are these dead-end jobs? How do we maintain long-term northern research programs - at least one generation in length? How can we develop value-added industries with local benefits that are complementary to the programs of multinational giants? ... Who is responsible for research that will lead to understanding, solutions, and management strategies? A few decades ago, the federal government provided research support, management policies, and policing. Now political devolution has resulted in multi-layers of governance in the North. Can we assume that this new governance system will invest in research that leads to new approaches? For example, who will invest in the monitoring of cumulative effects? If the linkage between government regulators and industry is too close, who will provide the long-term perspective so that environmental damage will not accrue to future generations? ... Maybe we should re-think the traditional role of government in light of the new power of industry. Many feel that industry-sponsored university research tarnishes the image of universities as honest brokers. ... Without budgets that reflect the realities of expensive northern research, researchers must stay close to their home institutions - and that is what they did in the 1980s and 1990s. ... I believe we need more northern research endowments in Canada. I believe we need more research and think tank nongovernmental organizations in Canada, and I believe these are increasingly important as the role of government changes from watchdog to stimulator of industry. ... There is also a need to reinterpret the 1970s information and to convert it into more usable forms. Much of this information was collected and stored in libraries and databases as private and public research collections were consolidated in the 1980s and 1990s. ... We must not forget that these resources are now much more accessible than they were in the 1970s. Finally, there is a need to capture the experience of many northern and southern people involved in the petroleum industry and many other activities in the 1970s and 1980s. ..

Microenvironmental Effects of Erosion Control Treatments on Seedling Survival in a Southeastern Utah Salt Desert Area

A study of the microclimate of erosion control treatments was carried out in two habitat types in a semiarid southeastern Utah, salt desert shrub area. The soils are highly eroded Mancos shale and support a low density of salt desert shrub species which offers little protection against high intensity summer convectional rainstorms. Gully plugs and contour furrows had been installed by the Bureaus of Reclamation and Land Management to prevent runoff of soil laden water which results from these summer rainfalls. Formerly this sediment was carried to the Colorado River and deposited in Lake Powell. The purpose to t he study was to measure some parameters that influenced establishment and survival of seedlings which would stabilize the structures and increase the productivity of the area. Mature, indigenous species close to the structures had greater vigor and provided a larger, more constant seed source. This seed source was important since original seedlings of introduced grasses have failed to establish and stabilize the structures . Following favorable late winter and early spring precipitation, high numbers of seedlings emerged, but few survived into mid-summer. Those that did survive were found only at or near the high water line of the gully plugs and in the bottom of contour furrows. To aid in the explanation of the differential seedling survival, soil surface moisture following rainstorms, physical and chemical soil characteristics, net radiation, soil surface temperature, and evaporation were investigated. Sampling of the 15 centimeter soil surface in the environs of the structures showed that two days after either heavy or light rainfalls, essentially no available water remained on the sloping throw positions of the structures. The bottom of the gully plugs remained flooded for several days. As a result, the seedlings were drowned. Only at the high water line of the gully plugs and in the bottom of furrows was there enough water to support seedling growth in summer. Runoff water from summer storms carried fine material into the structures, which covered and destroyed seedlings, plus lowered infiltration and permitted much of the water to be lost through evaporation. The runoff water also carried salts brought to the surface by the desert shrubs or by the upward movement of water during evaporation from the soil surface. Sampling of soil in the environs of the structures showed no substantial build up of salt, indicating that leaching had occurred, or still was occurring. This does not mean that a build up will not result in the future. Seasonal salt distribution showed that lowest salinity levels did not always coincide with springtime when seedlings generally emerged. Established seedlings were also exposed to a harsh environment of high soil surface temperatures (over 60 C) and high soil water evaporation rates that were detrimental to their survival. In summary, the study showed that the erosion control structures have created a microenvironment much different from the undisturbed soil, which only permits the establishment of species with much different tolerances from the indigenous species

Reference concentrations for trace elements in urine for the Brazilian population based on q-ICP-MS with a simple dilute-and-shoot procedure

Biomonitoring of trace elements is of critical importance in human health assessment. However, trace element concentrations in biological fluids are affected by environmental and physiological parameters, and therefore considerable variations can occur between specific population subgroups. Brazil is a large country with large environmental diversity and with a limited knowledge of the reference values (baseline data) for trace elements in biological fluids. Atomic absorption spectrometry (AAS) and inductively coupled plasma emission spectrometry (ICP-OES) are still the dominant analytical techniques used for biomonitoring trace element analysis in clinical specimens. However, the use of ICP-MS is becoming more usual in clinical laboratory analysis. Then, we evaluated here a simple dilute-and-shoot method for sequential determination of Al, Ba, Be, Cd, Co, Cu, Cs, Mn, Ni, Pb, Pt, Sb, Se, Sn, Tl and U in urine by quadrupole inductively coupled plasma mass spectrometry (q-ICP-MS). Urine samples (500 µL) were accurately pipetted into conical tubes (15 mL) and diluted to 10 mL with a solution containing 0.5 % (v/v) HNO3 + 0.005% (v/v) Triton X-100. Diluted urine samples also contain rhodium, iridium and yttrium added as internal standards. After that, samples were directly analyzed by ICP-MS against matrix-matching calibration. Method detection limit (3s, n = 20) were in the ng L-1 range for all analytes. The method was applied to the analysis of 412 ordinary urine samples from Brazilian healthy and non-exposed subjects to establish reference values. Data validation was provided by the analysis of the standard reference material (SRM) 2670a toxic elements in urine (freeze-dried) (high and low levels) from the National Institute of Standards and Technology (NIST) and reference urine samples from the trace elements intercomparison program operated by the Institut National de Sante' Publique du Quebec, Canada.O biomonitoramento de elementos químicos é de extrema importância na avaliação da saúde humana. Entretanto, as concentrações dos elementos químicos nos fluidos biológicos são afetadas por parâmetros ambientais e fisiológicos e, consequentemente, consideráveis variações podem ocorrer entre subgrupos de populações específicas. O Brasil é um país com ampla diversidade ambiental e existe limitado conhecimento de valores de referência para elementos químicos em fluidos biológicos. A espectrometria de absorção atômica (AAS) e a espectrometria de emissão ótica com plasma acoplado indutivamente (ICP-OES) ainda são as técnicas analíticas mais comumente empregadas no biomonitoramento de elementos químicos em amostras clínicas. Entretanto, o uso da espectrometria de massas com plasma acoplado indutivamente (ICP-MS) está se tornando a cada dia mais comum nos laboratórios clínicos. Neste estudo, foi avaliado um método rápido envolvendo simples diluição da amostra para determinação de Al, Ba, Be, Cd, Co, Cu, Cs, Mn, Ni, Pb, Pt, Sb, Se, Sn, Tl e U em urina por ICP-MS. Amostras de urina (500 μL) foram pipetadas em frascos cônicos de 15 mL e diluídas para 10 mL com uma solução contendo 0,5 % (v/v) HNO3 + 0,005% (v/v) Triton X-100. Ródio, irídio e ítrio foram adicionados como padrões internos. Em seguida, as amostras foram diretamente analisadas por ICP-MS com calibração por ajuste de matriz. Os limites de detecção do método (3s, n = 20) foram da ordem de ng L-1 para todos os analitos em estudo. O método foi aplicado para a análise de 412 amostras de urina de brasileiros saudáveis e não expostos ambientalmente ou ocupacionalmente a metais para o estabelecimento de valores de referência na população brasileira. A validação dos resultados foi acompanhada pela análise de material de referência certificada de urina (SRM) 2670a proveniente do National Institute of Standards and Technology (NIST) e de materiais de referência provenientes do Institut National de Sante' Publique Du Quebec, no Canadá.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Preparation of (Pb,Ba)TiO3 powders and highly oriented thin films by a sol-gel process

Solid solution Pb1-xBaxTiO3, with particular emphasis on Pb0.5Ba0.5TiO3, was prepared using a sol-gel process incorporating lead acetate trihydrate, barium acetate, and titanium isopropoxide as precursors, acetylacetone (2,4 pentanedione) as a chelating agent, and ethylene glycol as a solvent. The synthesis procedure was optimized by systematically varying acetylacetone: Ti and H2O:Ti molar ratios and calcination temperature. The resulting effects on sol and powder properties were studied using thermogravimetric analysis/differential scanning calorimetry, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller analysis, and x-ray diffraction (XRD). Crystallization of the perovskite structure occurred at a temperature as low as 450 °C. Thin films were prepared by spin coating on (100) MgO. Pyrolysis temperature and heating rate were varied, and the resultant film properties investigated using field-emission scanning electron microscopy, atomic force microscopy, and XRD. Under optimized conditions, highly oriented films were obtained at a crystallization temperature of 600 °C

The Areal Pattern of Burned Tree Vegetation in the Subarctic Region of Northwestern Canada

Vegetation and terrain analyses of 1312 air photos spanning the subarctic, low arctic, and portions of the adjacent high boreal region of northwestern Canada permitted geographic characterization of the areal pattern of burned forest and forest-tundra vegetation. In terms of its lower areal extent of burns, and lower frequency of air photos showing burns, the forest-tundra is distinct from both open crown and closed crown forest regions. Burns show a general decrease in areal coverage from the northwest (Mackenzie River to Great Bear Lake: 0-50% of the terrain) to the southeast (Great Slave Lake to Hudson Bay: 0-10%). In the northwest, the flat till plains, high cover of continuous mature forest, and scarcity of lakes, coupled with dominance of slowly regenerating white spruce (in the forest-tundra) may help to account for the extensive burned vegetation. In the eastern half of the study region, the northern limit of burns normally does not extend beyond the line where tree cover equals upland tundra cover. In this eastern sub-region, tree cover decreases rapidly northward within the southern half of forest-tundra, constraining the areal extent of individual burns. Burns extend about 25-75 km into the forest-tundra, decreasing in areal coverage with distance east of Great Slave Lake. Burn cover in the forest-tundra north of Great Slave Lake generally exceeds that east of Great Slave Lake. Weather patterns and an abundance of lakes may help to account for the lower cover of burns east of Great Slave Lake. Burns north of Great Slave Lake peak in cover in the low Subarctic along a NW-SE axis that lies NE of high fire risk and occurrence zones. Strong correlations were observed between burn cover and upland tundra cover (-r) and between burn cover and the tree:upland tundra cover ratio (+r).Key words: boreal, climate, fire ecology, Northwest Territories, spruce, Subarctic, vegetation, weatherMots clés: boréale, climat, écologie du feu, Territoires du Nord-aa-Ouest, épinette, Subarctique, végétation, clima

Mini-Brayton heat source assembly development

The work accomplished on the Mini-Brayton Heat Source Assembly program is summarized. Required technologies to design, fabricate and assemble components for a high temperature Heat Source Assembly (HSA) which would generate and transfer the thermal energy for a spaceborne Brayton Isotope Power System (BIPS) were developed