Development of an Integrated Algal/Seed Clam Unit Using Recirculation, Computer-Control, and Fluidization Technologies.

Computer-control, recirculation, and fluidized-bed technologies were utilized in the integration of a land-based seed clam nursery system with an algae production system to improve northern quahog seed production (6-10 mm). The components of the integrated system included: a seawater treatment system; an algae production system; a seed clam nursery system; and a computer-control system. Treatment of the incoming seawater for the integrated system included filtration (20, 1, and 0.5 micron), chlorination, UV sterilization, and ozonation. During the summer months a chiller was used to maintain the treated seawater at approximately \rm 20\sp\circ C. The diatom, Chaetoceros muelleri, was cultured in an algae production system which consisted of two 550 L tanks, covered with clear lexan to prevent the entrance of airborne contaminants. An air pump aerated and mixed the cultures and \rm CO\sb2 was injected into the airline to maintain pH. The biomass of the algal cultures was estimated using a HACH 1720C turbidimeter. Cultures were harvested when the estimated biomass concentration was greater than the control program set point. Harvest volume was set at 90% tank volume (450 L). After harvesting, the tanks were refilled with the treated seawater and resupplied with nutrients. The harvested algae was the food source for the land-based nursery seed clam system. The nursery system consists of six clear cylindrical upweller units (5 cm diameter, 76 cm in height); a 400 L feed reservoir, a solids separator, a bead filter \rm (0.03\ m\sp3) and a chiller. A high water flow velocity was maintained in the upweller units to fluidize the seed mass. Fluidizing the seed mass allows for the high density culture of seed by providing a more uniform distribution of food, and transporting waste material away from the seed mass. Individual upweller units obtained a biomass density of approximately 5.5 g whole wet weight clam per \rm cm\sp2 and greatest growth rates were observed when provided an effective daily algal ration of approximately 2% g dry weight algae per g whole wet weight clam

Learning from safety events in healthcare: A sensemaking and mental model perspective

Organizational learning from safety relevant events is critical for improvement of healthcare practice. The identification of causes of safety events in hospitals and the design of improvements engage decision making processes that involve a high degree of interpretive activity by various professional groups (physicians, nurses, risk managers, pharmacists, etc.). From a sensemaking perspective (Weick, 1995, Weick, Sutcliffe, & Obstfeld, 2005), we conceptualize the event investigation and action planning processes as driven by cognitive structures that help individuals understand an event from their own perspective, based on their experience, anticipation of what could happen, professional education and situational perceptions. To better understand these processes, we propose an individual-level framework suggesting that the construction of causal scenarios and the design of improvements are influenced by habitual mental models that contain assumptions and knowledge about safety and accident causation as well as by the analysts’ perceived action repertoires in defining corrective actions. Various influences on the individual cognitive processes in event analysis are discussed, such as professional education, cognitive style, organizational tools, culture, and the use of safety theories. As the framework is intended to stimulate future research, potential research questions and methods are discussed

Learning from safety events in healthcare: A sensemaking and mental model perspective

Organizational learning from safety relevant events is critical for improvement of healthcare practice. The identification of causes of safety events in hospitals and the design of improvements engage decision making processes that involve a high degree of interpretive activity by various professional groups (physicians, nurses, risk managers, pharmacists, etc.). From a sensemaking perspective (Weick, 1995, Weick, Sutcliffe, & Obstfeld, 2005), we conceptualize the event investigation and action planning processes as driven by cognitive structures that help individuals understand an event from their own perspective, based on their experience, anticipation of what could happen, professional education and situational perceptions. To better understand these processes, we propose an individual-level framework suggesting that the construction of causal scenarios and the design of improvements are influenced by habitual mental models that contain assumptions and knowledge about safety and accident causation as well as by the analysts’ perceived action repertoires in defining corrective actions. Various influences on the individual cognitive processes in event analysis are discussed, such as professional education, cognitive style, organizational tools, culture, and the use of safety theories. As the framework is intended to stimulate future research, potential research questions and methods are discussed

How Does Bankruptcy Risk Affect Stock Values?

Research in corporate restructuring argues that the risk of bankruptcy reduces firm value by the present value of both the direct and indirect costs of bankruptcy.  Additionally, the potential for bankruptcy affects both the investment horizon of investors and the discount rate implicit in equity values.  This paper empirically examines the effect of cross-sectional differences in the probability of bankruptcy on the determinants of firm value.  We estimate bankruptcy probabilities for an extensive sample of more than 38,000 firm-year observations over a twelve-year period.  Using a valuation model that employs both book value and earnings, we provide empirical evidence that earnings multiples decrease as the estimated probability of bankruptcy increases.  These results imply that investors and analysts rely less on current earnings and more on book value (which proxies for the firm’s liquidation value) as a firm’s probability of bankruptcy increases

Prehistoric Adaptations on Fishers Island, New York: Progress Report

Archaeological and paleoenvironmental research since 1985 on Fishers Island, New York has delineated a partially radiocarbon-dated Native American cultural sequence beginning in the Late Archaic period c. 4200 B.P. and ending at the Contact period c. A.D. 1600. Investigated settlement types included shell middens, lithic workshops, and inland hunting-gathering camps. Subsistence remains, including nuts, mollusks, and the bones of mammals, fishes, and birds indicate sporadic occupation of the island from spring through fall. Pollen recovered from both fresh water bogs and salt marshes evidence a typical postglacial forest succession beginning with the spruce-fir zone at about 13,000 B.P. and ending with the modern mixed deciduous forest

The End Of Nucleosynthesis: Production Of Lead And Thorium In The Early Galaxy

We examine the Pb and Th abundances in 27 metal-poor stars (-3.1 56) enrichment was produced only by the rapid (r-) nucleosynthesis process. New abundances are derived from Hubble Space Telescope/Space Telescope Imaging Spectrograph, Keck/High Resolution Echelle Spectrograph, and Very Large Telescope/UV-Visual Echelle Spectrograph spectra and combined with other measurements from the literature to form a more complete picture of nucleosynthesis of the heaviest elements produced in the r-process. In all cases, the abundance ratios among the rare earth elements and the third r-process peak elements considered (La, Eu, Er, Hf, and Ir) are constant and equivalent to the scaled solar system r-process abundance distribution. We compare the stellar observations with r-process calculations within the classical "waiting-point" approximation. In these computations a superposition of 15 weighted neutron-density components in the range 23 <= log n(n) <= 30 is fit to the r-process abundance peaks to successfully reproduce both the stable solar system isotopic distribution and the stable heavy element abundance pattern between Ba and U in low-metallicity stars. Under these astrophysical conditions, which are typical of the "main" r-process, we find very good agreement between the stellar Pb r-process abundances and those predicted by our model. For stars with anomalously high Th/Eu ratios (the so-called actinide boost), our observations demonstrate that any nucleosynthetic deviations from the main r-process affect-at most-only the elements beyond the third r-process peak, namely Pb, Th, and U. Our theoretical calculations also indicate that possible r-process abundance "losses" by nuclear fission are negligible for isotopes along the r-process path between Pb and the long-lived radioactive isotopes of Th and U.Deutsche Forschungsgemeinschaft KR 806/13-1Helmholtz Gemeinschaft VH-VI-061U S National Science Foundation AST 07-07447, AST 06-07708Astronom