4,301 research outputs found

    Overview of Charm Physics at RHIC

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    Heavy-quark production provides a sensitive probe of the gluon structure of nucleons and its modication in nuclei. It is also a key probe of the hot-dense matter created in heavy-ion collisions. We will discuss the physics issues involved, as seen in quarkonia and open heavy-quark production, starting with those observed in proton-proton collisions. Then cold nuclear matter effects on heavy-quark production including shadowing, gluon saturation, energy loss and absorption will be reviewed in the context of recent proton-nucleus and deuteron-nucleus measurements. Next we survey the most recent measurements of open-charm and J/Psi's in heavy-ion collisions at RHIC and their interpretation. We discuss the high-pT suppression and flow of open charm in terms of energy loss and thermalization and, for J/Psi, contrast explanations in terms of screening in a deconfined medium vs. recombination models.Comment: 6 pages, 12 figures, proceedings for Quark Confinement and Hadron Spectrum VI

    Regional Socioeconomic Impact of the Devils Lake Fishery

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    Community/Rural/Urban Development, Resource /Energy Economics and Policy,

    Hair Bundles of a Jawless Vertebrate Employ Tetrapod-Like Tuned Mechanical Amplification

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    In the hearing and balance organs of tetrapod vertebrates, mechanical signals are transduced by an elegant organelle called the hair bundle. Deflections of this structure apply forces to mechanically gated ion channels. Hair bundles are not passive receivers of stimuli, but are instead active participants in the process of sensory transduction. They expend chemical energy to exert mechanical work, and can harness this active process to amplify their mechanical response to stimuli. Furthermore, the active process is tuned, allowing a given hair bundle to preferentially amplify a particular frequency; this feature is valuable in the analysis of complex sounds. Hair bundles can also enter an unstable regime in which their active process drives spontaneous oscillations. Studying this epiphenomenon can reveal mechanisms underlying the amplifying abilities of hair bundles. Despite the importance of amplification in hearing, little is known regarding the evolution of the active process; it is unclear if the active process is exclusive to tetrapods. It would be instructive, for instance, to know whether the active process predates the array of auditory specializations seen throughout vertebrates. Here, we approach this problem by investigating the mechanical activity of the hair bundles from the inner ears of two jawless vertebrates, the sea lamprey Petromyzon marinus and the American brook lamprey Lampetra appendix. We observe spontaneous oscillations in both of these animals. In the latter species, we also show evidence that their oscillations stem from mechanisms similar to those driving the spontaneous oscillations of tetrapod vertebrates. Furthermore, we found that hair bundles exhibiting these movements can entrain to and mechanically amplify particular stimulus frequencies. Taken together, our findings from a group distantly related to the tetrapods suggest that the active process of hair bundles is trait ancestral to all vertebrate ears

    Intravenous conscious sedation in patients under 16 years of age. Fact or fiction?

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    Recently published guidelines on the use of conscious sedation in dentistry have published varying recommendations on the lower age limit for the use of intravenous conscious sedation. There are a large number of dentists currently providing dental treatment for paediatric patients under intravenous conscious sedation. The 18 cases reported here (age range 11-15 years), were successfully managed with intravenous conscious sedation. The experience in this paper is not sufficient evidence to recommend the wholesale use of intravenous conscious sedation in patients who are under 16 years. The fact that a range of operators can use these techniques on paediatric patients would suggest that further study should be carried out in this population. The guidance should be modified to say there is insufficient evidence to support the use of intravenous conscious sedation in children, rather than arbitrarily selecting a cut off point at age 16 years

    AN ECONOMIC ASSESSMENT OF WETLAND MITIGATION IN NORTHWEST MINNESOTA

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    The economic efficiency of wetland mitigation in Minnesota's Red River Valley was examined using the Minnesota Routine Assessment Method on ten wetland case studies to rate the functions of impacted and replacement wetlands. Secondary sources were used to assign dollar values to wetland functions of impacted and replacement wetlands. Mitigation costs for projects ranged from 279to279 to 4,171 per acre. Estimated annual social values ranged from 207to207 to 1,027 per acre for impacted wetlands and from 268to268 to 927 per acre for replacement wetlands. Social values of replacement wetlands exceeded the social value of impacted wetlands in seven cases. Values of replacement wetlands were 1.8 to 4 times greater than the values of impacted wetlands due to 2-to-1 replacement ratios. When society gains benefits from mitigation, public cost-sharing may be appropriate. In one case the value of the impacted wetlands was higher than the value of the replacement wetland. There were insufficient data to evaluate two cases. Results are only indicators of efficiency, since not all social costs and benefits of the impact-mitigation activity are addressed by legislation. These results suggest wetland mitigation policy in Minnesota needs to be reevaluated if efficient use of society's resources is a legislative goal.Wetland(s), mitigation, economics, values, Minnesota, Red River, Wetland Conservation Act, Minnesota Routine Assessment Method, restoration, Land Economics/Use,

    AN INQUIRY INTO THE RELATIONSHIP OF WETLAND REGULATIONS AND PROPERTY VALUES IN MINNESOTA

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    Ownership in property can be thought of as ownership of the rights to the "incomes" associated with different uses of the property. Each potential use has a separate economic value, which can be ranked if put into money terms. The property's market value is usually held to be the highest income on that ranking. Wetland protection regulations might shift the ownership of some of these rights from private to public entities or restrict the exercise of some rights. This can result in a reduction of the property's market value, if the regulation precludes access to the income from the highest ranking use. A regulation can never increase the economic value of a property from the owner's perspective. Whether or not a reduction in property value is considered "fair" is a question usually left to the courts. If it is determined that a regulation has resulted in a "taking" of property, compensation must be paid. The appropriate level of compensation is the difference between estimated pre- and post-regulation market values. The task of the analyst is to estimate those two values, after first determining if the two uses are feasible given other physical, financial, and legal conditions. Because property prices are not determined until there is a transaction, all such valuations are necessarily estimates based on the professional judgments of the analyst. There are not easy ways to determine these values short of costly individual appraisals or extensive market studies. Wetland regulations in Minnesota do result in reduced values for some property owners--as do all land use regulations. Demonstrating that values went down on regulated properties has policy import, however, only if: (1) the examples are so egregious that the Legislature decides to change the enabling legislation to adjust the distribution of the law's benefits and costs; or (2) the sum of measured property losses exceeds any estimate of total benefits, in which case the Legislature might decide to change the law as not in the broader public interest. Should further property value analyses be conducted? Only if the Legislature is very clear about why it wants to do the study. If the concern is one of fairness, then the distribution of a regulation's costs should be examined by using parcel-by-parcel appraisals or by a careful calculation of the economic benefits and costs among different classes of people, classes of property, or regions of the state. If, on the other hand, the concern is that the aggregate costs of the regulation may exceed its total benefits, then broader economic valuation studies are called for. We are not prepared to recommend either approach at this time, because the Legislature has not yet declared what the problem really is.Land Economics/Use,

    Andrew Ranson: Seventeenth Century Pirate?

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    The later half of the seventeenth century saw the swashbuckling heyday of piracy in the West Indies. Here, English, French, and Dutch buccaneers, and audacious seafarers claiming no nation, roamed the seas almost at will, delighting particularly in preying on galleons flying the Spanish flag and in sacking and ransoming cities along the Spanish Main. It is true that the policy of European nations was changing from encouraging or winking at buccaneer activities to supporting legitimate trade with Spanish America, and some serious efforts were made to curb these seagoing marauders. Nevertheless, this was of little consolation to the inhabitants of Panama, which was ravished by the Englishman Henry Morgan in 1671, or to those of Maracaibo, which was destroyed by the Dutchman l’Olonnais in 1667, or to those of Vera Cruz, which was surprised by the Frenchman the Sieur de Grammont in 1683. In this same period similar fates befell many other cities, and their hapless residents endured unspeakable indignities

    Lord Dunmore\u27s Loyalist Asylum in the Floridas

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    To the astonishment of many, Lord John Murray, fourth Earl of Dunmore, member of the House of Lords, formerly controversial colonial governor of New York and Virginia, became governor of the Bahama Islands in 1787. Immediately eyebrows were lifted and questions raised as to why the Earl had accepted the apparently insignificant governorship of islands whose total population, black and white, was not appreciably greater than that of Williamsburg when the colonial assembly had been in session. Dunmore had returned to America late in 1781 and had expected to resume his role as the Virginia governor in the wake of Cornwallis’ victories; but the defeat at Yorktown was responsible for his arriving at British-occupied Charleston rather than the governor’s palace at Williamsburg. Examining Dunmore’s post-1781 career helps explain what eventually drew him to the Bahamas and also clarifies British policy toward the Floridas, Louisiana, and the entire Mississippi Valley in the 1782-1783 Paris peace negotiations
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