1,331 research outputs found
A Comparison of Diets and Water Agitation Methods for Larval Culture of the Edible Sea Urchin, Tripneustes ventricosus (Echinodermata: Echinoidea)
Tripneustes ventricosus (Lamarck, 1816) has been harvested for human consumption in the Caribbean for centuries, where harvest rates occasionally exceed sustainability. Historically a backreef and grass-bed urchin, the species has recently been observed on the forereef where it appears to control macroalgal growth in the absence of Diadema antillarum (Philippi, 1845) (Woodley and Gayle, 1999). Large-scale culturing has the potential to produce T. ventricosus in sufficient numbers for remediation of degraded coral reefs, restocking of nearshore habitats, and development of an aquaculture industry for one or more Caribbean islands. We report the first successful culturing of T. ventricosus from fertilization to exotrophic juvenile and the results of experiments to measure the effectiveness of agitation methods and diets applicable to large-scale larval culture. Airlift agitation was not effective in the 3.78-L (1-gal) jars used here. Cultures were successfully reared without mechanical agitation, but paddle agitation, used successfully in many small-scale experimental designs, produced the highest survival rates. Of the five algal diets tested, Rhodomonas sp., and a mixture of Rhodomonas Karsten and Isochrysis Parke, produced the most rapid development (23 d to metamorphosis). Isochrysis aff. galbana (Tahitian strain) supported slower development (36 d to metamorphosis) but produced the highest (48%) survival rate
THE ARMORED SCALE INSECTS (HEMIPTERA DIASPIDIDAE) OF ALABAMA, USA
A continuing survey of the armored scale insects of Alabama has resulted in recording 113 species in 47 genera, among the tribes Aspidiotini, Diaspidini, and Odonaspidini. Alabama now ranks second among states in the southeastern United States in number of species of armored scales, trailing only Florida with its 150+ species. Comments on some of the more notable diaspidids, not previously collected in Alabama, are made along with notes on their hosts and distribution in the State
A study of concept options for the evolution of Space Station Freedom
Two conceptual evolution configurations for Space Station Freedom, a research and development configuration, and a transportation node configuration are described and analyzed. Results of pertinent analyses of mass properties, attitude control, microgravity, orbit lifetime, and reboost requirements are provided along with a description of these analyses. Also provided are brief descriptions of the elements and systems that comprise these conceptual configurations
Proceedings, International Taxus Symposium, October 1, 1975
History and development of Taxus in the U.S. / Ray A. Keen -- The best of the Taxus cultivars / L. C. Chadwick -- Poisonous properties of Taxus / Jack L. Beal -- Production of Taxus / Arie J. Radder -- Effective use of Taxus in the landscape / Clarence E. Lewis -- Taxus species and hybrids / Harold G. Hillier -- Japanese yew (Taxus cuspidata) / Makoto Kawase -- Fertilizing Taxus for optimum growth / Elton M. Smith -- Taxus insects: problems and research in Ohio / David G. Nielsen -- Taxus locations in the Secrest Arboretu
Use of a pressure sensing sheath: comparison with standard means of blood pressure monitoring in catheterization procedures
PURPOSE: Monitoring of blood pressure (BP) during procedures is variable, depending on multiple factors. Common methods include sphygmomanometer (BP cuff), separate radial artery catheterization, and side port monitoring of an indwelling sheath. Each means of monitoring has disadvantages, including time consumption, added risk, and signal dampening due to multiple factors. We sought an alternative approach to monitoring during procedures in the catheterization laboratory.
METHODS: A new technology involving a 330 microm fiberoptic sensor embedded in the wall of a sheath structure was tested against both radial artery catheter and sphygmomanometer readings obtained simultaneous with readings recorded from the pressure sensing system (PSS). Correlations and Bland-Altman analysis were used to determine whether use of the PSS could substitute for these standard techniques.
RESULTS: The results indicated highly significant correlations in systolic, diastolic, and mean arterial pressures (MAP) when compared against radial artery catheterization (p \u3c 0.0001), and MAP means differed by \u3c 4%. Bland-Altman analysis of the data suggested that the sheath measurements can replace a separate radial artery catheter. While less striking, significant correlations were seen when PSS readings were compared against BP cuff readings.
CONCLUSIONS: The PSS has competitive functionality to that seen with a dedicated radial artery catheter for BP monitoring and is available immediately on sheath insertion without the added risk of radial catheterization. The sensor is structurally separated from the primary sheath lumen and readings are unaffected by device introduction through the primary lumen. Time delays and potential complications from radial artery catheterization are avoided
Pion-nucleus elastic scattering on 12C, 40Ca, 90Zr, and 208Pb at 400 and 500 MeV
Pion-nucleus elastic scattering at energies above the Delta(1232) resonance
is studied using both pi+ and pi- beams on 12C, 40Ca, 90Zr, and 208Pb. The
present data provide an opportunity to study the interaction of pions with
nuclei at energies where second-order corrections to impulse approximation
calculations should be small. The results are compared with other data sets at
similar energies, and with four different first-order impulse approximation
calculations. Significant disagreement exists between the calculations and the
data from this experiment
Why have asset price properties changed so little in 200 years
We first review empirical evidence that asset prices have had episodes of
large fluctuations and been inefficient for at least 200 years. We briefly
review recent theoretical results as well as the neurological basis of trend
following and finally argue that these asset price properties can be attributed
to two fundamental mechanisms that have not changed for many centuries: an
innate preference for trend following and the collective tendency to exploit as
much as possible detectable price arbitrage, which leads to destabilizing
feedback loops.Comment: 16 pages, 4 figure
Bright X-ray and Radio Pulses from a Recently Reactivated Magnetar
Magnetars are young, rotating neutron stars that possess larger magnetic fields (B ≈ 10¹³-10¹⁵G) and longer rotational periods (P ≈ 1-12 s) than ordinary pulsars. In contrast to rotation-powered pulsars, magnetar emission is thought to be fueled by the evolution and decay of their powerful magnetic fields. They display highly variable radio and X-ray emission, but the processes responsible for this behavior remain a mystery. We report the discovery of bright, persistent individual X-ray pulses from XTE J1810-197, a transient radio magnetar, using the Neutron star Interior Composition Explorer (NICER) following its recent radio reactivation. Similar behavior has only been previously observed from a magnetar during short time periods following a giant flare. However, the X-ray pulses presented here were detected outside of a flaring state. They are less energetic and display temporal structure that differs from the impulsive X-ray events previously observed from the magnetar class, such as giant flares and short X-ray bursts. Our high frequency radio observations of the magnetar, carried out simultaneously with the X-ray observations, demonstrate that the relative alignment between the X-ray and radio pulses varies on rotational timescales. No correlation was found between the amplitudes or temporal structure of the X-ray and radio pulses. The magnetar's 8.3 GHz radio pulses displayed frequency structure, which was not observed in the pulses detected simultaneously at 31.9 GHz. Many of the radio pulses were also not detected simultaneously at both frequencies, which indicates that the underlying emission mechanism producing these pulses is not broadband. We find that the radio pulses from XTE J1810-197 share similar characteristics to radio bursts detected from fast radio burst (FRB) sources, some of which are now thought to be produced by active magnetars
Bright X-ray and Radio Pulses from a Recently Reactivated Magnetar
Magnetars are young, rotating neutron stars that possess larger magnetic fields (B ≈ 10¹³-10¹⁵G) and longer rotational periods (P ≈ 1-12 s) than ordinary pulsars. In contrast to rotation-powered pulsars, magnetar emission is thought to be fueled by the evolution and decay of their powerful magnetic fields. They display highly variable radio and X-ray emission, but the processes responsible for this behavior remain a mystery. We report the discovery of bright, persistent individual X-ray pulses from XTE J1810-197, a transient radio magnetar, using the Neutron star Interior Composition Explorer (NICER) following its recent radio reactivation. Similar behavior has only been previously observed from a magnetar during short time periods following a giant flare. However, the X-ray pulses presented here were detected outside of a flaring state. They are less energetic and display temporal structure that differs from the impulsive X-ray events previously observed from the magnetar class, such as giant flares and short X-ray bursts. Our high frequency radio observations of the magnetar, carried out simultaneously with the X-ray observations, demonstrate that the relative alignment between the X-ray and radio pulses varies on rotational timescales. No correlation was found between the amplitudes or temporal structure of the X-ray and radio pulses. The magnetar's 8.3 GHz radio pulses displayed frequency structure, which was not observed in the pulses detected simultaneously at 31.9 GHz. Many of the radio pulses were also not detected simultaneously at both frequencies, which indicates that the underlying emission mechanism producing these pulses is not broadband. We find that the radio pulses from XTE J1810-197 share similar characteristics to radio bursts detected from fast radio burst (FRB) sources, some of which are now thought to be produced by active magnetars
- …