Structure-based analysis of the ultraspiracle protein and docking studies of putative ligands

The ultraspiracle protein (USP) is the insect ortholog of the mammalian retinoid X receptor (RXR). Fundamental questions concern the functional role of USP as the heterodimerization partner of insect nuclear receptors such as the ecdysone receptor. The crystallographic structures of the ligand binding domain of USPs of Heliothis virescens and Drosophila melanogaster solved recently show that helix 12 is locked in an antagonist conformation raising the question whether USPs could adopt an agonist conformation as observed in RXRα. In order to investigate this hypothesis, a homology model for USP is proposed that allows a structural analysis of the agonist conformation of helix 12 based on the sequence comparison with RXR. For USP, one of the main issues concerns its function and in particular whether its activity is ligand independent or not. The x-ray structures strongly suggest that USP can bind ligands. Putative ligands have therefore been docked in the USP homology model. Juvenile hormones and juvenile hormone analogs were chosen as target ligands for the docking study. The interaction between the ligand and the receptor are examined in terms of the pocket shape as well as in terms of the chemical nature of the residues lining the ligand binding cavity

Protection And Conservation Of Marine Mammals In Canada: A Case For Legislative Reform

The twentieth century was the century of modem whaling, as new technologies allowed whalers to exploit enormous numbers of whales from all oceans for processing into various products for industry and trade. Seals and sirenians (manatees and dugongs) were also heavily exploited in the 1900s, adversely affecting the populations of certain species. On entering the twenty-first century, numerous governments and organizations, and much of the general public now regard marine mammals, especially cetaceans, as having aesthetic and economic importance as well as intrinsic value outside the realm of exploitation. During the past decade, general awareness of the need to study the natural world at the ecosystem level has heightened, and it is recognized that threats to the survival of marine mammals go beyond that of commercial exploitation. Potential threats include habitat degradation, noise and chemical pollution, accidental strikes by ships, and incidental catch by commercial fisheries. Strategies for resolving these problems include the creation of marine protected areas to protect critical habitat, international cooperation in the development of conservation programs, and an increase in biological research to enhance management. The formulation of strong conservation policies and legislation at the national level is necessary to provide guidance for the implementation of these potential solutions. There is precedence at the international level for the types of protection needed. One example is the global moratorium on commercial whaling initiated in 1982 and implemented in 1986 by the International Whaling Commission (1WC). Despite the moratorium, however, a number of large whale species, including the right, Eubalaena glacialis; bowhead, Balaena mysticetus; blue, Balaenoptera musculus; sperm, Physeter macrocephalus; and humpback, Megaptera novaeangliae, are still considered endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), the U.S. Division of Endangered Species, and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). International whale sanctuaries were declared by a large majority of IWC members; for example, in 1979, in the Indian Ocean to 550S latitude; and in 1994 in the waters of the Southern Hemisphere, south of 40°S latitude. The prohibition against commercial whaling activities in these waters illustrates strong international support for the protection of whales. Since the declaration of the International Convention for the Regulation of Whaling (ICRW) in 1946, other international environmental conventions have been established. Several of these conventions have had implications for marine mammals and have set the stage for global conservation activities, including the United Nations Convention on the Law of the Sea (UNCLOS), the United Nations Conference on Environment and Development Agenda 21 action plan, the Convention on the Conservation of Migratory Species of Wild Animals (Bonn Convention), CITES, and the Convention on Biological Diversity (CBD). While some nations have enacted legislation and taken policy stands on the protection and conservation of marine mammals, national legislative protection for marine mammals is far from universal. Canada, a nation normally recognized for its strong environmental and natural heritage initiatives, largely views marine mammals as a resource to be exploited. Canada was a signatory to the ICRW and a member of the International Whaling Commission (IWC), but in 1982 withdrew its membership stating it no longer had an interest in whaling. However, aboriginal whaling in Canada continues with annual takes of approximately seven hundred beluga, Delphinapterus leucas; and three hundred narwhal, Monodon monoceros, respectively. Since 1991, there has been a renewed interest in bowhead hunting in the western Arctic by native communities after some sixty years of not hunting this species. In 1996, after a twenty year pause, communities in the eastern Arctic also resumed bowhead whaling. The eastern bowhead stock is considered highly endangered-less than five hundred are thought to remain-and the international community has responded strongly to this problem. Walrus, Odobenus rosmarus, and up to ten species of seal can be taken by aboriginal peoples in Canada; harp, Pagophilus groenlandicus; and hooded seals, Cystophora cristata; are all hunted commercially by non-aboriginals. Canada has maintained a firm pro-commercial sealing policy, which has strengthened over the years despite public and international opposition. Currently, there are no comprehensive conservation programs or initiatives for marine mammals, and no deliberate legislative or policy commitments for their protection. Under the Canadian system, marine mammals and other marine animals are included in the definition of fish in the Fisheries Act. The definition of fish first appeared in the Fisheries Act in 1927. Despite numerous amendments of the Fisheries Act, this biologically invalid definition has been retained. Because of the lack of a comprehensive conservation framework, and the biologically inaccurate classification of marine mammals as fish, marine mammal management has suffered. Marine mammals should not be defined as fish, and arguments against this definition can be made on the basis of science, values, and management. The great biological differences between these two taxa, at both the physiological and behavioral levels, lead necessarily to different management requirements. Societal attitudes toward fish and marine mammals are different, and they are valued in different ways for different reasons. For example, fish is a primary food resource that represents a major basis of revenue, and a significant contribution to the economies of many communities. Marine mammals have intrinsic value, non-consumptive tourism value, and cultural/subsistence value for numerous Aboriginal communities, but limited commercial exploitation value. A program designed to manage the exploitation of one will not address the conservation issues of the other. In Canada, Fisheries and Oceans Canada, the administrative body for ocean and ocean resource issues, is focused primarily on conserving diverse fish stocks for industry. Thus, absent an economic rationale as the driving force for the conservation of marine mammals, such industry concerns will necessarily take precedence over domestic conservation concerns. International treaties often lack provisions for seals because it is assumed that their conservation is a domestic issue, even though many are highly migratory. Thus, domestic legislation is particularly important for the reason that seals normally reside within coastal waters and the Exclusive Economic Zone (EEZ) of a nation. For the above reasons, special legislation for marine mammals is warranted as the basis for enhanced management and protection. The United States, Australia, and New Zealand have enacted legislation for the protection of marine mammals that is separate from the legislation pertaining to fisheries, and each nation has deliberately avoided considering them as fish. For example, the now repealed 1952 Australian Fisheries Act explicitly excluded all cetaceans from the definition of fish, and by 1991, under the Australian Fisheries Management Act, all marine mammals were excluded from the definition. Canada\u27s continued adherence to this definition has been detrimental because it defines the way government, including fisheries and wildlife managers, perceive marine mammals, and influences the way humans use marine mammals in Canada. This article examines the limitations existing within Canada\u27s policy and legislative initiatives for the conservation and protection of marine mammals, as compared with other selected nations. The United States, Australia, and New Zealand are the jurisdictions chosen for comparison, because these nations possess the most advanced marine mammal legislation, regulations, and programs in the world, and because they are similar to Canada in terms of commitment to the environment and conservation. International conventions relating to marine mammals were reviewed, and special emphasis was placed on Canada\u27s obligations under these conventions. The main components integral to effective marine mammal conservation in those jurisdictions were used to mold a revised framework to increase marine mammal protection in Canada, and to further enhance the Canadian legislative and regulatory structure. Recommendations stemming from this framework fit both the current legislative structure and an ecosystem approach to marine conservation under Canada\u27s Oceans Act

Protection And Conservation Of Marine Mammals In Canada: A Case For Legislative Reform

The twentieth century was the century of modem whaling, as new technologies allowed whalers to exploit enormous numbers of whales from all oceans for processing into various products for industry and trade. Seals and sirenians (manatees and dugongs) were also heavily exploited in the 1900s, adversely affecting the populations of certain species. On entering the twenty-first century, numerous governments and organizations, and much of the general public now regard marine mammals, especially cetaceans, as having aesthetic and economic importance as well as intrinsic value outside the realm of exploitation. During the past decade, general awareness of the need to study the natural world at the ecosystem level has heightened, and it is recognized that threats to the survival of marine mammals go beyond that of commercial exploitation. Potential threats include habitat degradation, noise and chemical pollution, accidental strikes by ships, and incidental catch by commercial fisheries. Strategies for resolving these problems include the creation of marine protected areas to protect critical habitat, international cooperation in the development of conservation programs, and an increase in biological research to enhance management. The formulation of strong conservation policies and legislation at the national level is necessary to provide guidance for the implementation of these potential solutions. There is precedence at the international level for the types of protection needed. One example is the global moratorium on commercial whaling initiated in 1982 and implemented in 1986 by the International Whaling Commission (1WC). Despite the moratorium, however, a number of large whale species, including the right, Eubalaena glacialis; bowhead, Balaena mysticetus; blue, Balaenoptera musculus; sperm, Physeter macrocephalus; and humpback, Megaptera novaeangliae, are still considered endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), the U.S. Division of Endangered Species, and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). International whale sanctuaries were declared by a large majority of IWC members; for example, in 1979, in the Indian Ocean to 550S latitude; and in 1994 in the waters of the Southern Hemisphere, south of 40°S latitude. The prohibition against commercial whaling activities in these waters illustrates strong international support for the protection of whales. Since the declaration of the International Convention for the Regulation of Whaling (ICRW) in 1946, other international environmental conventions have been established. Several of these conventions have had implications for marine mammals and have set the stage for global conservation activities, including the United Nations Convention on the Law of the Sea (UNCLOS), the United Nations Conference on Environment and Development Agenda 21 action plan, the Convention on the Conservation of Migratory Species of Wild Animals (Bonn Convention), CITES, and the Convention on Biological Diversity (CBD). While some nations have enacted legislation and taken policy stands on the protection and conservation of marine mammals, national legislative protection for marine mammals is far from universal. Canada, a nation normally recognized for its strong environmental and natural heritage initiatives, largely views marine mammals as a resource to be exploited. Canada was a signatory to the ICRW and a member of the International Whaling Commission (IWC), but in 1982 withdrew its membership stating it no longer had an interest in whaling. However, aboriginal whaling in Canada continues with annual takes of approximately seven hundred beluga, Delphinapterus leucas; and three hundred narwhal, Monodon monoceros, respectively. Since 1991, there has been a renewed interest in bowhead hunting in the western Arctic by native communities after some sixty years of not hunting this species. In 1996, after a twenty year pause, communities in the eastern Arctic also resumed bowhead whaling. The eastern bowhead stock is considered highly endangered-less than five hundred are thought to remain-and the international community has responded strongly to this problem. Walrus, Odobenus rosmarus, and up to ten species of seal can be taken by aboriginal peoples in Canada; harp, Pagophilus groenlandicus; and hooded seals, Cystophora cristata; are all hunted commercially by non-aboriginals. Canada has maintained a firm pro-commercial sealing policy, which has strengthened over the years despite public and international opposition. Currently, there are no comprehensive conservation programs or initiatives for marine mammals, and no deliberate legislative or policy commitments for their protection. Under the Canadian system, marine mammals and other marine animals are included in the definition of fish in the Fisheries Act. The definition of fish first appeared in the Fisheries Act in 1927. Despite numerous amendments of the Fisheries Act, this biologically invalid definition has been retained. Because of the lack of a comprehensive conservation framework, and the biologically inaccurate classification of marine mammals as fish, marine mammal management has suffered. Marine mammals should not be defined as fish, and arguments against this definition can be made on the basis of science, values, and management. The great biological differences between these two taxa, at both the physiological and behavioral levels, lead necessarily to different management requirements. Societal attitudes toward fish and marine mammals are different, and they are valued in different ways for different reasons. For example, fish is a primary food resource that represents a major basis of revenue, and a significant contribution to the economies of many communities. Marine mammals have intrinsic value, non-consumptive tourism value, and cultural/subsistence value for numerous Aboriginal communities, but limited commercial exploitation value. A program designed to manage the exploitation of one will not address the conservation issues of the other. In Canada, Fisheries and Oceans Canada, the administrative body for ocean and ocean resource issues, is focused primarily on conserving diverse fish stocks for industry. Thus, absent an economic rationale as the driving force for the conservation of marine mammals, such industry concerns will necessarily take precedence over domestic conservation concerns. International treaties often lack provisions for seals because it is assumed that their conservation is a domestic issue, even though many are highly migratory. Thus, domestic legislation is particularly important for the reason that seals normally reside within coastal waters and the Exclusive Economic Zone (EEZ) of a nation. For the above reasons, special legislation for marine mammals is warranted as the basis for enhanced management and protection. The United States, Australia, and New Zealand have enacted legislation for the protection of marine mammals that is separate from the legislation pertaining to fisheries, and each nation has deliberately avoided considering them as fish. For example, the now repealed 1952 Australian Fisheries Act explicitly excluded all cetaceans from the definition of fish, and by 1991, under the Australian Fisheries Management Act, all marine mammals were excluded from the definition. Canada\u27s continued adherence to this definition has been detrimental because it defines the way government, including fisheries and wildlife managers, perceive marine mammals, and influences the way humans use marine mammals in Canada. This article examines the limitations existing within Canada\u27s policy and legislative initiatives for the conservation and protection of marine mammals, as compared with other selected nations. The United States, Australia, and New Zealand are the jurisdictions chosen for comparison, because these nations possess the most advanced marine mammal legislation, regulations, and programs in the world, and because they are similar to Canada in terms of commitment to the environment and conservation. International conventions relating to marine mammals were reviewed, and special emphasis was placed on Canada\u27s obligations under these conventions. The main components integral to effective marine mammal conservation in those jurisdictions were used to mold a revised framework to increase marine mammal protection in Canada, and to further enhance the Canadian legislative and regulatory structure. Recommendations stemming from this framework fit both the current legislative structure and an ecosystem approach to marine conservation under Canada\u27s Oceans Act

A Synoptic Climatology of Derecho Producing Mesoscale Convective Systems in the North-Central Plains

Synoptic-scale environments favourable for producing derechos, or widespread convectively induced windstorms, in the North-Central Plains are examined with the goal of providing pattern-recognition:diagnosis techniques. Fifteen derechos were identified across the North-Central Plains region during 1986–1995. The synoptic environment at the initiation, mid-point and decay of each derecho was then evaluated using surface, upper-air and National Center for Atmospheric Research (NCAR):National Center for Environmental Prediction (NCEP) reanalysis datasets. Results suggest that the synoptic environment is critical in maintaining derecho producing mesoscale convective systems (DMCSs). The synoptic environment in place downstream of the MCS initiation region determines the movement and potential strength of the system. Circulation around surface low pressure increased the instability gradient and maximized leading edge convergence in the initiation region of nearly all events regardless of DMCS location or movement. Other commonalities in the environments of these events include the presence of a weak thermal boundary, high convective instability and a layer of dry low-to-mid-tropospheric air. Of the two corridors sampled, northeastward moving derechos tend to initiate east of synoptic-scale troughs, while southeastward moving derechos form on the northeast periphery of a synoptic-scale ridge. Other differences between these two DMCS events are also discussed

Resource Recovery from Wastewater Treatment Sludge Containing Gypsum

The disposal of wastewater treatment sludge generated at the Radford Army Ammunition Plant (RAAP) is a serious problem. The sludge is produced by neutralizing spent acid contained in the wastewater with lime, and consists principally of very finely divided wet gypsum (calcium sulfate dihydrate). Although the sludge is presently being disposed of in a landfill, the sludge is difficult to handle and convert into a load-bearing material. Therefore an alternative method of disposal is being developed and evaluated. The alternative method involves drying and granulating the sludge, followed by high temperature calcination in a fluidized bed reactor to recover usable sulfur dioxide and lime. If the method is adopted, these products would be used within the plant with considerable cost savings. The sulfur dioxide would be added to the feed stream of an oleum manufacturing facility and the lime would be reused in wastewater treatment

Role of 5-HT receptor mechanisms in sub-chronic PCP-induced reversal learning deficits in the rat

YesRationale: 5-HT receptor mechanisms have been suggested to mediate improvements in cognition in schizophrenia. Aim: To investigate the involvement of 5-HT receptor mechanisms in sub-chronic PCP-induced reversal learning deficits in female rats, a task of relevance to schizophrenia. Methods: Adult female hooded-Lister rats were trained to perform an operant reversal learning task and then received sub-chronic PCP (2 mg/kg) or vehicle i.p. twice daily for seven days, followed by 7-days washout. Rats then received an acute dose of the 5-HT7 receptor antagonist SB-269970A (1.0, 3.0, 10.0 mg/kg; i.p.) or vehicle. In experiment 2, PCP-treated rats received the selective 5-HT2C receptor antagonist, SB-243213A acutely (1.0, 3.0, 10.0 mg/kg; i.p.) or vehicle. In experiment 3, PCP-treated rats received the 5-HT1A receptor partial agonist, buspirone (0.15625, 0.3125, 0.625 mg/kg, i.p.) in combination with the selective 5-HT1A receptor antagonist WAY-100635 (0.3, 1.0 mg/kg). Results: In all experiments sub-chronic PCP significantly impaired reversal phase performance (P<0.01-0.001), with no effect in the initial phase. SB-269970A at 3.0 and 10.0 mg/kg significantly improved the PCP-induced deficit (P<0.05). SB-243213A also significantly attenuated the deficit at 10 mg/kg (P<0.05). In experiment 3, buspirone attenuated the deficit with significant effects at 0.3125 mg/kg and 0.625 mg/kg (P<0.05). WAY-100635 at 0.3 and 1.0 mg/kg produced a partial attenuation of buspirone’s effect as buspirone (0.3125 mg/kg) in the presence of WAY-100635 did not significantly reverse the PCP-induced deficit. Conclusions: These studies implicate the role of 5-HT7, 5-HT2C and 5-HT1A receptors in the improvement of cognitive dysfunction of relevance to schizophrenia

On the Topology of Black Hole Event Horizons in Higher Dimensions

In four dimensions the topology of the event horizon of an asymptotically flat stationary black hole is uniquely determined to be the two-sphere $S^2$. We consider the topology of event horizons in higher dimensions. First, we reconsider Hawking's theorem and show that the integrated Ricci scalar curvature with respect to the induced metric on the event horizon is positive also in higher dimensions. Using this and Thurston's geometric types classification of three-manifolds, we find that the only possible geometric types of event horizons in five dimensions are $S^3$ and $S^2 \times S^1$. In six dimensions we use the requirement that the horizon is cobordant to a four-sphere (topological censorship), Friedman's classification of topological four-manifolds and Donaldson's results on smooth four-manifolds, and show that simply connected event horizons are homeomorphic to $S^4$ or $S^2\times S^2$. We find allowed non-simply connected event horizons $S^3\times S^1$ and $S^2\times \Sigma_g$, and event horizons with finite non-abelian first homotopy group, whose universal cover is $S^4$. Finally, following Smale's results we discuss the classification in dimensions higher than six.Comment: 12 pages, minor edits 27/09/0

A fast branch-and-prune algorithm for the position analysis of spherical mechanisms

The final publication is available at link.springer.comDifferent branch-and-prune schemes can be found in the literature for numerically solving the position analysis of spherical mechanisms. For the prune operation, they all rely on the propagation of motion intervals. They differ in the way the problem is algebraically formulated. This paper exploits the fact that spherical kinematic loop equations can be formulated as sets of 3 multi-affine polynomials. Multi-affinity has an important impact on how the propagation of motion intervals can be performed because a multi-affine polynomial is uniquely determined by its values at the vertices of a closed hyperbox defined in its domain.Peer ReviewedPostprint (author's final draft

New Longevity Record for Ivory Gulls (Pagophila eburnea) and Evidence of Natal Philopatry

Ivory gulls (Pagophila eburnea) have been listed as “endangered” in Canada and “near threatened” interna-tionally. In June 2010, we visited Seymour Island, Nunavut, Canada, where gulls were banded in the 1970s and 1980s. We recaptured and released two breeding gulls banded as chicks in 1983, confirming natal philopatry to this breeding colony. These gulls are more than 28 years old, making the ivory gull one of the longest-living marine bird species known in North America.La mouette blanche (Pagophila eburnea) figure sur la liste des espèces « en voie de disparition » sur la scène canadienne et des espèces « quasi menacées » sur la scène internationale. En juin 2010, nous sommes allés à l’île Seymour, au Nunavut, Canada, où des mouettes avaient été baguées dans le courant des années 1970 et 1980. Nous avons recapturé et relâché deux mouettes reproductrices qui étaient considérées comme des oisillons en 1983, ce qui nous a permis de confirmer la philopatrie natale de cette colonie de nidification. Ces mouettes blanches ont plus de 28 ans, ce qui en fait l’un des oiseaux aquatiques vivant le plus longtemps en Amérique du Nord

Occupational radiation exposure at commercial nuclear power reactors and other facilities 1995: Twenty-eighth annual report. Volume 17

This report summarizes the occupational exposure data that are maintained in the US Nuclear Regulatory Commission`s (NRC) Radiation Exposure Information and Reporting System (REIRS). The bulk of the information contained in the report was compiled from the 1995 annual reports submitted by six of the seven categories of NRC licensees subject to the reporting requirements of 10 CFR 20.2206. Since there are no geologic repositories for high-level waste currently licensed, only six categories will be considered in this report. In 1995, the annual collective dose per reactor for light water reactor licensees (LWRs) was 199 person-cSv (person-rem). This is the same value that was reported for 1994. The annual collective dose per reactor for boiling water reactors (BWRs) was 256 person-cSv (person-rem) and, for pressurized water reactors (PWRs), it was 170 person-cSv (person-rem). Analyses of transient worker data indicate that 17,153 individuals completed work assignments at two or more licensees during the monitoring year. The dose distributions are adjusted each year to account for the duplicate reporting of transient workers by multiple licensees. In 1995, the average measurable dose calculated from reported data was 0.26 cSv (rem). The corrected dose distribution resulted in an average measurable dose of 0.32 cSv (rem)