1,039 research outputs found
Alien Registration- Marcoux, Asias A. (Sanford, York County)
https://digitalmaine.com/alien_docs/2672/thumbnail.jp
Early Cretaceous biogeographic and oceanographic synthesis of Leg 123 (off Northwestern Australia)
Biogeographic observations made by Leg 123 shipboard paleontologists for Lower Cretaceous nannofossils, foraminifers,
radiolarians, belemnites, and inoceramids are combined in this chapter to evaluate the paleoceanographic history
of the northwestern Australian margin and adjacent basins. Each fossil group is characterized at specific intervals of
Cretaceous time and compared with data from Tethyan and Southern Hemisphere high-latitude localities. Special attention
is given to the biogeographic observations made for the Falkland Plateau (DSDP Legs 36 and 71) and the Weddell Sea
(ODP Leg 113). Both areas have yielded valuable Lower Cretaceous fossil records of the circumantarctic high latitudes.
In general, the Neocomian fossil record from DSDP and ODP sites off northwestern Australia has important southern
high-latitude affinities and weak Tethyan influence. The same is true for the pelagic lithofacies: radiolarian chert and/or
nannofossil limestone, dominant in the Tethyan Lower Cretaceous, are minor lithologies in the Exmouth-Argo sites.
These observations, together with the young age of the Argo crust and plate tectonic considerations, suggest that the Argo
Basin was not part of the Tethys Realm.
The biogeography of the Neocomian radiolarian and nannofossil assemblages suggests opening of a seaway during
the Berriasian that connected the circumantarctic area with the Argo Basin, which resulted in the influx of southern
high-latitude waters.
This conclusion constrains the initial fit and break-up history of Gondwana. Our results favor the loose fit of the
western Australian margin with southeast India by Ricou et al. (1990), which accounts for a deeper water connection with
the Weddell-Mozambique basins via drowned marginal plateaus as early as the Berriasian. In fits of the du Toit-type
(1937), India would remain attached to Antarctica, at least until the late Valanginian, making such a connection
impossible.
After the Barremian, increasing Tethyan influence is evident in all fossil groups, although southern high-latitude taxa
are still present. Biogeographic domains, such as the southern extension of Nannoconus and Ticinella suggest paleolatitudes
of about 50°S for the Exmouth-Argo area. Alternatively, if paleolatitudes of about 35° are accepted, these
biogeographic limits were displaced northward at least 15° along Australia in comparison to the southern Atlantic. In this
case, the proto-circumantarctic current was deflected northward into an eastern boundary current off Australia and carried
circumantarctic cold water into the middle latitudes.
Late Aptian/early Albian time is characterized by mixing of Tethyan and southern faunal elements and a significant
gradient in Albian surface-water temperatures over 10° latitude along the Australian margin, as indicated by planktonic
foraminifers. Both phenomena may be indicative of convergence of temperate and antarctic waters near the Australian
margin. High fertility conditions, reflected by radiolarian cherts, are suggestive of coastal upwelling during that time
Distance-Restricted Firefighting on Finite Graphs
In the classic version of the game of firefighter, on the first turn a fire
breaks out on a vertex in a graph and then firefighters protect
vertices. On each subsequent turn, the fire spreads to the collective unburnt
neighbourhood of all the burning vertices and the firefighters again protect
vertices. Once a vertex has been burnt or protected it remains that way for
the rest of the game. We previously introduced the concept of
where the firefighters' movement is
restricted so they can only move up to some fixed distance and they may or
may not be permitted to move through burning vertices. In this paper we
establish the NP-Completeness of the distance-restricted versions of the
problem and present an integer program for
solving these problems. In the penultimate section we also discuss some
interesting properties of the function
Does Digoxin Provide Additional Hemodynamic and Autonomic Benefit at Higher Doses in Patients With Mild to Moderate Heart Failure and Normal Sinus Rhythm?
AbstractObjectives. This study sought to examine the hemodynamic and autonomic dose response to digoxin.Background. Previous studies have demonstrated an increase in contractility and heart rate variability with digitalis preparations. However, little is known about the dose-response to digoxin, which has a narrow therapeutic window.Methods. Nineteen patients with moderate heart failure and a left ventricular ejection fraction <0.45 were studied hemodynamically using echocardiography and blood pressure at baseline and after 2 weeks of low dose (0.125 mg daily) and 2 weeks of moderate dose digoxin (0.25 mg daily). Loading conditions were altered with nitroprusside at each study. Autonomic function was studied by assessing heart rate variability on 24-h Holter monitoring and plasma norepinephrine levels during supine rest.Results. Low dose digoxin provided a significant increase in ventricular performance, but no further increase was seen with the moderate dose. Low dose digoxin reduced heart rate and increased heart rate variability. Moderate dose digoxin produced no additional increase in heart rate variability or reduction in sympathetic activity, as manifested by heart rate, plasma norepinephrine or low frequency/high frequency power ratio. In addition, we did not find that either low or moderate dose digoxin increased parasympathetic activity.Conclusions. We conclude that moderate dose digoxin provides no additional hemodynamic or autonomic benefit for patients with mild to moderate heart failure over low dose digoxin. Because higher doses of digoxin may predispose to arrhythmogenesis, lower dose digoxin should be considered in patients with mild to moderate heart failure.(J Am Coll Cardiol 1997;29:1206–13
Effect of metoprolol on myocardial function and energetics in patients with nonischemic dilated cardiomyopathy: A randomized, double-blind, placebo-controlled study
AbstractObjectives. This study examined the of metoprolol on left ventricular performance, efficiency, neurohormonal activation and myocardial respiratory quotient in patients with dilated cardiomyopathy.Background.The mechanism by which beta-adrenergie blockade improves ejection fraction in patients with dilated cardiomyopathy remains an enigma. Thus, we undertook an extensive hemodynamic evaluation of this mechanism. In addition, because animal models have shown that catecholamine exposure may increase relative fatty acid utilization, we hypothesized that antagonism of sympathetic stimulation may result in increased carbohydrate utilization.Methods. This was a randomized, double-blind, prospective trial in which 24 men with nonischemic dilated cardiomyopathy underwent cardiac catheterization before and after 3 months of therapy with metoprolol (n = 15) or placebo (n = 9) in addition to standard therapy. Pressure-volume relations were examined using a micromanometer catheter and digital ventriculography.Results. At baseline, the placebo-treated patients had somewhat more advanced left ventricular dysfunction. Ejection fraction and left ventricular performance improved only in the metoprolol-treated patients. Stroke and minute work increased without an increase in myocardial oxgen consumption, suggesting increased myocardial efficiency. Further increases in ejection fraction were seen between 3 and 6 months in the metoprolol group. The placebo group had a significant increase in ejection fraction only after crossover to metoprolol. A significant relation the change in coronary sinus norepinephrine and myocardial respiratory quotient was seen, suggesting a possible effect of adrenergic deactivation on substrate utilization.Conclusions. These data demonstrate that in patients with cardiomyopthy, metoprolol treatment improves myocardial performance and energetics, and favorably alters substrate utilization. Beta-adrenergic blocking agents, such as metoprolol, are hemodynamically and energetically beneficial in the treatment of myocardial failure
Migration, Dispersal, and Gene Flow of Harvested Aquatic Species in the Canadian Arctic
Migration occurs when key aspects of the life cycle such as growth, reproduction, or maintenance cannot all be completed in one location. The Arctic habitats are variable and Arctic species are often migratory. The predictable nature of migrations in both space and time allow Arctic people to harvest fishes and marine mammals. We describe migratory/dispersal behavior in four types of taxa from the Canadian Arctic: anadromous and freshwater fishes, marine fishes, marine invertebrates, and marine mammals. Patterns of migration are remarkably different between these groups, in particular between distances migrated, seasonal timing of migrations, and the degree of reproductive isolation. Migratory anadromous and freshwater fishes become adapted to specific locations resulting in complex life histories and intra- and inter-population variation. Marine mammals not only migrate longer distances but also appear to have distinct demographic populations over large scales. Marine fishes tend to be panmictic, probably due to the absence of barriers that would restrict gene flow. Migratory patterns also reflect feeding or rearing areas and/or winter refugia. Migratory patterns of harvested aquatic organisms in the Canadian north are extremely variable and have shaped the north in terms of harvest, communities, and culture
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