Investigation of the effects of NaOH dopant level on the physical and mechanical properties of carbon/phenolic composite material

The near-catastrophic erosion of the STS-8A solid rocket booster nozzle was the instigating factor in the recent, and on-going, intensive investigation of carbon/phenolic composite materials. Much of this effort has been focused on the effect of sodium contamination on the carbon fibers. It is known that sodium acts as a catalyst in the oxidation of the fibers at elevated temperatures. A study was undertaken to determine what changes were caused by variation in sodium content. Investigations were conducted in three areas: (1) phenolic resin; (2) carbon/phenolic prepreg; and (3) cured laminates. Due to the exploratory nature of the studies, a variety of tests in addition to those normally run in production facilities were considered. The experimental methodologies and results of these experiments are discussed, and recommendations for improving techniques and extending the research program are presented

A Survey Of IPv6 Address Usage In The Public Domain Name System

The IPv6 protocol has been slowly increasing in use on the Internet. The main reason for the development of the protocol is that the address space provided by IPv4 is nearing exhaustion. The pool of addresses provided by IPv6 is 296 times larger than IPv4, and should be sufficient to provide an address for every device for the foreseeable future. Another potential advantage of this significantly large address space is the use of randomly assigned addresses as a security barrier as part of a defence in depth strategy. This research examined the addresses allocated by those implementing IPv6 to determine what method or pattern of allocation was being used by adopters of the protocol. This examination was done through the use of DNS queries of the AAAA IPv6 host record using public DNS servers. It was observed that 55.84% of IPv6 addresses were in the range of 0 to (232 − 1). For those addresses with unique interface identifier (IID) portions, a nearly equal number of sequential and random IIDs were observed. Hong Kong and Germany were found to have the greatest number of IPv6 addresses. These results suggest that adopters are allocating most addresses sequentially, meaning that no security advantage is being obtained. It is unclear as to whether this is through design or the following of accepted practice. Future research will continue to survey the IPv6 address space to determine whether the patterns observed here remain constant

Dynamic Factor Price Equalization & International Convergence

We offer a duality-based methodology for incorporating multi-sector effects of international trade into open economy macroeconomic models, developing the concepts of the dynamic factor price equalization set and the integrated intertemporal equilibrium. Under this approach, the aggregate production function depends on output prices and factor endowment stocks. It preserves all of the structure of a standard GDP function from the trade theory literature. In a two-country version of the model considered below, we examine the properties of the dynamic factor price equalization set. If the global economy is initially outside of this set, the equations of motion will pull the economy back into this set. Inside the dynamic FPE set, factor prices are equalized internationally, and with identical tastes and technology, the economy can be regarded as a fully integrated world equilibrium in a dynamic sense (the integrated intertemporal equilibrium). In this equilibrium, all of the standard properties of a closed economy one-sector neoclassical growth model hold, ruling out cycles and chaos, and allowing us to characterize the evolution of international inequality and the persistence of productivity and endowment shocks. Working from the integrated intertemporal equilibrium, we identify properties of persistence linked to inequality and real economic shocks. Cross-country differences in per capita incomes and wealth, and the factor content of trading patterns, may persist over time and even into the new steady state. This provides yet another reason why we might observe lack of income convergence internationally. In addition, real shocks in one country may be transmitted to the other country through factor markets and product prices, and may have persistent effects into the steady-state as well. The model can also generate an endogenous Balassa-Samuelson effect.Neoclassical Models of Trade, Economic Growth of Open Economies, Cross- Country Output Convergence

Bias in U.S. Import Prices and Demand

The purpose of the paper is to measure the potential bias in the U.S. import price index due to the appearance of new product varieties, or new foreign suppliers, and determine the effect of this bias on the estimated income elasticity of import demand. Existing import price indexes are based on a sample of products from importing firms. We argue that if the share of import expenditure on the sampled products is falling over time, this will lead to an upward bias in the measured index. Using a correction based on the falling expenditure share on sampled countries, we find that the income elasticity of aggregate U.S. import demand is reduced from 2.5 to 1.7, or about halfway to unity. Our estimates suggest that the aggregate import price index is upward biased by about one and one-half percentage points annually.

Prison(er) auto/biography, 'true crime', and teaching, learning, and research in criminology

The main aim of this essay is to explore prisoner life writing within the specific, richly and multiply dependent context of teaching and learning undergraduate criminology at an English university, from the authorial viewpoint of a teacher and her students as budding criminologists and co-authors. This article seeks to redress a continuing resistance to life history approaches in the teaching of criminology, despite the discipline being formally devoted to the understanding of the meaning and experience of imprisonment in all its forms and consequences. What follows is a trucated narrative of what students had to say on the fascinating subjects of prisoner auto/biography and its place in popular and expert discourses on crime, criminality, and punishment, contextualised within the academic discipline of criminology

PROMOTIONAL EFFORTS VS. ECONOMIC FACTORS AS DRIVERS OF PRODUCERS' DECISIONS TO EXPAND OR START A DAIRY

Replaced with revised version of paper 07/13/04.Farm Management,

Dynamic Factor Price Equalization & International Convergence

We offer a duality-based methodology for incorporating multi-sector effects of international trade into open economy macroeconomic models, developing the concepts of the dynamic factor price equalization set and the integrated intertemporal equilibrium. Under this approach, the aggregate production function depends on output prices and factor endowment stocks. It preserves all of the structure of a standard GDP function from the trade theory literature. In a two-country version of the model considered below, we examine the properties of the dynamic factor price equalization set. If the global economy is initially outside of this set, the equations of motion will pull the economy back into this set. Inside the dynamic FPE set, factor prices are equalized internationally, and with identical tastes and technology, the economy can be regarded as a fully integrated world equilibrium in a dynamic sense (the integrated intertemporal equilibrium). In this equilibrium, all of the standard properties of a closed economy one-sector neoclassical growth model hold, ruling out cycles and chaos, and allowing us to characterize the evolution of international inequality and the persistence of productivity and endowment shocks. Working from the integrated intertemporal equilibrium, we identify properties of persistence linked to inequality and real economic shocks. Cross-country differences in per capita incomes and wealth, and the factor content of trading patterns, may persist over time and even into the new steady state. This provides yet another reason why we might observe lack of income convergence internationally. In addition, real shocks in one country may be transmitted to the other country through factor markets and product prices, and may have persistent effects into the steady-state as well. The model can also generate an endogenous Balassa-Samuelson effect

Radial glia in the proliferative ventricular zone of the embryonic and adult turtle, Trachemys scripta elegans.

To better understand the role of radial glial (RG) cells in the evolution of the mammalian cerebral cortex, we investigated the role of RG cells in the dorsal cortex and dorsal ventricular ridge of the turtle, Trachemys scripta elegans. Unlike mammals, the glial architecture of adult reptile consists mainly of ependymoradial glia, which share features with mammalian RG cells, and which may contribute to neurogenesis that continues throughout the lifespan of the turtle. To evaluate the morphology and proliferative capacity of ependymoradial glia (here referred to as RG cells) in the dorsal cortex of embryonic and adult turtle, we adapted the cortical electroporation technique, commonly used in rodents, to the turtle telencephalon. Here, we demonstrate the morphological and functional characteristics of RG cells in the developing turtle dorsal cortex. We show that cell division occurs both at the ventricle and away from the ventricle, that RG cells undergo division at the ventricle during neurogenic stages of development, and that mitotic Tbr2+ precursor cells, a hallmark of the mammalian SVZ, are present in the turtle cortex. In the adult turtle, we show that RG cells encompass a morphologically heterogeneous population, particularly in the subpallium where proliferation is most prevalent. One RG subtype is similar to RG cells in the developing mammalian cortex, while 2 other RG subtypes appear to be distinct from those seen in mammal. We propose that the different subtypes of RG cells in the adult turtle perform distinct functions

Overview of NASA Initiatives in 3D Printing and Additive Manufacturing

No abstract availabl