69,933 research outputs found

    Oyster Bed Mapping in the Great Bay Estuary, 2012-2013

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    Six major oyster beds (reefs) in New Hampshire are mapped periodically to assess wild oyster populations in the Great Bay Estuary. Data on the spatial extent of the beds are combined with density and other measures to estimate the abundances of live oysters. The first objective of the present project was to determine the spatial extent of these six oyster beds, and to compare the 2012/2013 data with previous mapping efforts. A second objective was twofold: to map the extent of live oyster bottom at selected recent oyster restoration sites, and to map areas where oyster beds have been known to occur historically but not recently. Towed underwater video methods, as used in previous oyster mapping efforts in New Hampshire, were used for this project. All recorded video was classified into three categories: ”reef” (\u3e20% shell cover and live oysters visible); ”sparse shell” ( Two of the natural beds (Nannie Island [2012: 32.4 ac] and Oyster River [2012: 1.6 ac]) had similar total bottom area coverage compared to most previous mapping efforts. Three beds (Adams Point [2012: 15.9 ac], Squamscott River [2012: 7.7 ac] and Woodman Point [2012: 15.4 ac]) had substantially greater area coverage compared to previous surveys. In all three cases, however, the increases were likely due to additional adjacent areas being surveyed. In contrast to the others, the Piscataqua River bed appears to have substantially decreased in bottom area coverage (2012: 7.0 ac) compared to previous surveys. Selected oyster restoration sites were also video surveyed in 2013 to determine bottom area coverage that could be considered “reef” and therefore considered as part of the overall oyster resource in New Hampshire. Restoration sites in the Lamprey River, Oyster River (3 sites), and at Fox Point in Little Bay were imaged. Due to poor image quality, full bottom area coverage could not be determined for any of the sites. Nonetheless, substantial areas of at least “sparse shell” bottom, and live oysters in some areas were recorded at all sites. These restoration sites as well as additional sites are scheduled for video surveying and quantitative sampling in 2013. The third focus of the project was to survey areas where oyster beds historically occurred. Of the four general areas surveyed, live oyster reefs were found in two areas: Lamprey River (0.9 ac) and mid-Great Bay (35.2 ac). In sum, these two areas represent a major addition to the known live oyster bottom in the state. Moreover, these findings strongly suggest that live oyster reefs may be in other areas where oysters have not been known to exist in recent years. Overall, this project has added substantially to our knowledge of where live oysters occur in New Hampshire as well as the total bottom area coverage. A total of 120 acres of bottom area classified as “reef” was mapped. Additionally, the extent (perhaps 100 ac or more) of bottom area that had sparse shell but apparently few or no live oysters in mid-Great Bay bed and in the Nannie Island/Woodman Point area is important because these areas represent excellent oyster restoration opportunities. However, they will need to be mapped in more detail to sufficiently design future projects

    Cozymase. A study of purification methods

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    Cozymase is one of the essential components of the complex enzyme mixture which effects alcoholic fermentation in the absence of living cells. The separation of the mixture into zymase and cozymase was first accomplished by Harden and Young [1] by means of ultrafiltration through a gelatin-impregnated Chamberland filter candle. The residue and filtrate as thus prepared possessed, separately, no fermentative action, but when mixed were found to produce a rapid fermentation. The active constituent of the residue was named zymase, while that constituent of the filtrate responsible for the reactivation of the residue was named cozymase. We studied the purification produced in our material by a variety of reagents. In the investigation we have repeated much of the work done by von Euler and Myrbäk [2], and several differences have been found, which appear difficult to explain solely upon the basis of the lower initial purity of our material. As certain of the experiments show distinct promise, we hope to be able to extend the work upon a material of considerably higher original purity, such as was employed by von Euler and Myrbäk

    Experimental Quantification of Nutrient Bioextracti on Potential of Oysters in Estuarine Waters of New Hampshire

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    This project was a short-term field experiment conducted in summer 2010 and designed to provide preliminary data on the bioextraction (removal) of carbon (C) and nitrogen (N) for two different size classes (both \u3c76mm shell height) of eastern oysters (Crassostrea virginica) at six sites in the Great Bay estuarine system in New Hampshire. Sites were chosen to represent a range of ambient nutrient concentrations, water flow conditions, and location within the estuary. Two of the sites were at oyster aquaculture farms: Granite State Shellfish at the mouth of the Oyster River, and Little Bay Oyster Company near Fox Point in Little Bay. At each site, oysters were deployed in 10mm mesh polyethylene bags typically used on oyster farms in New England. Approximately one thousand “seed” size (10?15 mm shell height), or two hundred (200) 1?year old (30?40 mm shell height) oysters were placed into each bag. Two bags (one for each size class) were suspended 10?20 cm off the bottom attached to plastic coated wire cages at each site from August 9 until November 4, 2010. The oysters were inspected and the bags were cleaned each month to reduce fouling. There were no significant differences in final size among the six sites, indicating similar growth rates. Soft tissue %C and %N values, however, varied substantially and significantly (ANOVA, P\u3c0.05) among the sites. Tukey tests indicated significantly higher %C and %N at the Squamscott River (SQ) site, and significantly lower at the Little Bay Oyster (LBO) farm site, compared to the other sites. The ranges of mean soft tissue %C and %N were, respectively, 26.9 to 47.2 and 4.7 to 10.6. Because shell material was not analyzed in the present study, literature values for shell were combined with soft tissue data from the present study to arrive at total whole animal C and N content. Oysters with mean shell height of 35.7 mm contained 0.6 g of C and 0.01 g of N; oysters with mean shell height of 55.6 mm contained 3.1 g of C and 0.07 g of N. Preliminary calculations indicated that if 20 0 acres of bottom area were in full farm production, the annual N removal from the estuary from oyster harvest alone would be 12.56 tons. It is emphasized that the present study represents only the first step in characterizing the nutrient (focusing on N) bioextraction potential for oyster farming in New Hampshire

    Selectable towline spin chute system

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    An emergency spin recovery parachute is presented that is housed within a centrally mounted housing on the aft end of an aircraft and connected to a ring fitting within the housing. Two selectively latching shackles connected to separate towlines are openly disposed adjacent the ring fitting. The towlines extend in opposite directions from the housing along the aircraft wing to attachment points adjacent the wing-tips where the other end of each towline is secured. Upon pilot command, one of the open shackles latches to the ring fitting to attach the towline connected thereto, and a second command signal deploys the parachute. Suitable break-away straps secure the towlines to the aircraft surface until the parachute is deployed and the resulting force on the towline attached to the parachute overcomes the straps and permits the towline to extend to the point of attachment to exert sufficient drag on the spinning aircraft to permit the pilot to regain control of the aircraft. To employ the parachute as a drag chute to reduce landing speeds, both shackles and their respective towlines are latched to the ring fitting

    Nitrous Oxide: Mechanism of Its Antinociceptive Action

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    Nitrous oxide (N2O) is an anesthetic gas known to produce an analgesic effect at sub-anesthetic concentrations. This analgesic property of N2O can be clinically exploited in a broad range of conditions where pain relief is indicated. The mechanism of this analgesic effect was long thought to be nonspecific in nature, but a landmark study by Berkowitz and others in 1976 first implicated an opioid mechanism of action, possibly via N2O-stimulated neuronal release of endogenous opioid peptides to activate opioid receptors. N2O-induced release of opioid peptide has been demonstrated in both in vivo and in vitro preparations. Reversal of N2O-induced antinociception in animals by narcotic antagonists has been reported by a number of laboratories. Subsequent studies have utilized more selective opioid antagonists to identify the opioid receptor subtypes involved in the antinociceptive effect of N2O. Extensive pharmacological testing in the mouse abdominal constriction and rat hot plate paradigms have established that N2O-induced antinociception is mediated by κ-opioid receptors in the former and by µ- and -opioid receptors in the latter. Current studies focus on two recent developments. The poor responsiveness of the DBA/2J mouse strain to N2O has led to pharmacogenetic studies that hope to identify the underlying genetic basis for antinociceptive responsiveness to N2O. Other research suggests an involvement of nitric oxide (NO) in mediating the antinociceptive effects of N2O in both rats and mice

    Optimal Hedging Strategies for the U.S. Cattle Feeder

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    Multiproduct optimal hedging is compared to alternative hedging strategies as applied to a Midwestern cattle feeder. One-period feeding margin hedge ratios are estimated using weekly cash and futures price data from a simulation of a custom feedlot for 1983 ??? 1995. Hedge ratios are estimated using the last 4 years, 6 years, or all prior data available at the moment of estimation; the ratios demonstrate less variability as the length of the underlying sample increases. Hypothesis of all hedge ratios being equal to each other, that leads to the proportional hedging model, is rejected. Means and variances of hedged feeding margins using the computed hedge ratios suggest that there is no consistent domination pattern among the alternative strategies. For the ratios computed based on all prior data available, all strategies are on the efficient frontier, leaving the hedging decision up to the agent???s degree of risk aversion. All hedging strategies are shown to significantly reduce the feeding margin???s means and variances compared to no hedging, with variance reduction always exceeding 50 percent. Whether a producer chooses multiproduct, single-commodity, or proportional hedge ratios is sensitive to the dataset and its size.published or submitted for publicationnot peer reviewe
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