Aerometry instrumentation study Final report

Techniques and instruments for meteorological measurements in Mars and Venus atmosphere

Correlation of the Model and Prototype Tests of the Conchas Dam Service Spillway and Stilling Basin

Conchas Dam and Reservoir, one of the largest water resources projects in the Southwest, build under the supervision of Corps of Engineers, is located below the confluence of the Conchas River and South Canadian River, near Tucumcari, New Mexico. Although it is the source of water supply for the vast Tucumcari Irrigation Project of the U.S. Bureau of Reclamation, its main purpose is flood control. Conchas Dam exerts a tremendous influence on the economy of the northeastern portion of Texas. To a hydraulic engineer its large size and complex hydraulic features present a most challenging field for study and researc

Population and Economics in Ireland in the Recent Past and in the Near Future. ESRI Memorandum Series No. 148 1981

There is far more to population than economics. The existence of any person now is the result of one chance in countless billions of possibilities down the ages so, by this test, the value of a person is immeasurably great whatever her or his social status, though this may not appear about ourselves or to us about our fellow humans, there are so many of us. The existence of a person will usually create love and ether social relations of incomparable significance. We are aware that in law and in less worthy connections (including kidnapping) the question of valuation of a person can arise; figures are mentioned but they cannot be regarded seriously as statistics. At one time in Ireland* long ago the argument was rife in respectable circles that because it cost 1,000 to rear an emigrant the country lost 20 million a year if emigration amounted to 20,000 persons. R. C. Geary's (1941) refutation of this thesis is nowadays as likely to amuse as to instruct. You may hold that human existence is always better than non-existence, a philosophical question which shall not concern us. Our approach is almost exclusively statistical. We bear in mind, however, the peroration of Sean Lemass at the Centenary Banquet in 1947 of the SSISI. "The best things in life are not measurable by statistics and we pray that they will remain so". We mention non-statistical values lest they be forgotten. Population policy may be determined by such values, despite any statistical showing; this is for the people to determine. There may be no such conflict

Utilization of Saltmarsh Shorelines by Newly Settled Sciaenids in a Texas Estuary

Post-settlement patterns of habitat use along saltmarsh shorelines of Galveston Bay, Texas were examined for three sciaenids; spotted seatrout (Cynoscion nebulosus), red drum (Sciaenops ocellatus), and Atlantic croaker (Micropogonias undulatus). Collections were made summer through fall of 1997 and 1998 using a 1.5-m beam trawl hand-towed along the outside edge of salt marshes. Sciaenids were collected from tidal pass, bay, and remote tidal creek areas to assess large-scale (bay-wide) patterns of distribution and abundance. Cynoscion nebulosus were smaller and most numerous at bay stations, with densities peaking in June. Conversely, S. ocellatus were collected in higher numbers, and smaller sizes, at stations near the tidal pass, with peak densities in September. Micropogonias undulatus occurred in high numbers near both the tidal pass and remote tidal creeks, with undetectable size differences among areas and peak densities in November. Densities of C. nebulosus and S. ocellatus were greater at sites nearer the larval supply; patterns were less clear for M. undulatus. Small-scale patterns of habitat use were investigated within remote tidal creeks, with trends in density and size apparent for M. undulatus, while few C. nebulosus and S. ocellatus were collected. Interannual variability in densities occurred within and among stations, although total densities for each species were relatively similar between 1997 and 1998

Quantitative Deficits of Preschool Children at Risk for Mathematical Learning Disability

The study tested the hypothesis that acuity of the potentially inherent approximate number system (ANS) contributes to risk of mathematical learning disability (MLD). Sixty-eight (35 boys) preschoolers at risk for school failure were assessed on a battery of quantitative tasks, and on intelligence, executive control, preliteracy skills, and parental education. Mathematics achievement scores at the end of 1 year of preschool indicated that 34 of these children were at high risk for MLD. Relative to the 34 typically achieving children, the at risk children were less accurate on the ANS task, and a one standard deviation deficit on this task resulted in a 2.4-fold increase in the odds of MLD status. The at risk children also had a poor understanding of ordinal relations, and had slower learning of Arabic numerals, number words, and their cardinal values. Poor performance on these tasks resulted in 3.6- to 4.5-fold increases in the odds of MLD status. The results provide some support for the ANS hypothesis but also suggest these deficits are not the primary source of poor mathematics learning

Fatigue crack growth in iron silicon alloys.

A technique for accurately monitoring fatigue crack growth at near threshold growth rates has been established. The characteristics of near threshold fatigue crack growth of a number of iron-silicon alloys has been quantitatively and qualitatively investigated. Relationships have been established relating the stress intensity factor, AK, and the fatigue crack growth rate da/dN. At fatigue crack growth rates approaching threshold the material has shown some microstructural sensitivity and this has been related to the stress intensity factor and the yield stress.A relationship has been shown to exist between the value of the threshold stress intensity factor and the inverse root of the grain size, d~2, for each of the alloys investigated. A model for near threshold fatigue crack growth has been proposed and includes the contributions made by grain size and crack tip plasticity.This work has also shown that fatigue crack closure plays an important role in the micromechanisms of fatigue crack growth near the threshold at low R ratio s. A number of mechanisms have been identified: crack closure due tothe presence of oxidation products on fracture surfaces in tests conducted in air, and closure due to the presence of fatigue fretting, facet contact and a contribution of mixed mode opening

The fate of an endothelium layer after preconditioning

BackgroundA strategy in minimizing thrombotic events of vascular constructs is to seed the luminal surface with autologous endothelial cells (ECs). The task of seeding ECs can be achieved via bioreactors, which induce mechanical forces (shear stress, strain, pressure) onto the ECs. Although bioreactors can achieve a confluent layer of ECs in vitro, their acute response to blood remains unclear. Moreover, the necessary mechanical conditions that will increase EC adhesion and function remain unclear. We hypothesize that preconditioning seeded endothelium under physiological flow will enhance their retention and function.ObjectiveTo determine the role of varying preconditioning protocols on seeded ECs in vitro and in vivo.MethodsScaffolds derived from decelluarized arteries seeded with autologous ECs were preconditioned for 9 days. Three specific protocols, low steady shear stress (SS), high SS, and cyclic SS were investigated. After preconditioning, the seeded grafts were exposed to 15 minutes of blood via an ex vivo arteriovenous shunt model or alternately an in vivo arteriovenous bypass graft model.ResultsThe shunt model demonstrated ECs remained intact for all conditions. In the arteriovenous bypass model, only the cyclic preconditioned grafts remained intact, maintained morphology, and resisted the attachment of circulating blood elements such as platelets, red blood cells, and leukocytes. Western blotting analysis demonstrated an increase in the protein expression of eNOS and prostaglandin I synthase for the cyclic high shear stress-conditioned cells relative to cells conditioned with high shear stress alone.ConclusionCyclic preconditioning has been shown here to increase the ECs ability to resist blood flow-induced shear stress and the attachment of circulating blood elements, key attributes in minimizing thrombotic events. These studies may ultimately establish protocols for the formation of a more durable endothelial monolayer that may be useful in the context of small vessel arterial reconstruction.Clinical RelevanceThe importance of ECs toward patency has been demonstrated by the superior performance of endothelialized vein compared with prosthetic vascular graft materials. This article evaluates conditioning protocols for bioengineered vascular conduits to improve endothelial retention. This study describes approaches to improve bioengineered vessels as a potential alternative to conventional prosthetic vascular grafts