Rapid Prototyping at Zero Gravity for In-Flight Repairs and Fabrication on Space Station Freedom

The ability to perform in-flight rapid prototyping would be of great benefit to NASA in two ways. First, repair parts could be fabricated from CAD designs beamed up from earth based laboratories which might allow a failed experiment to proceed. The mission specialists themselves, under the creative influence of space flight, might design a new part or tool and fabricate it on board in a matter of hours. Second, with metal casting and ceramic sintering facilities on board, rapid prototyping would allow manufacturing in space. This paper presents some test criteria for evaluating two of the rapid prototyping techniques, stereolithography and fused deposition, in microgravity conditions. Effects of the variation of head speed and strip width for the fused deposition process on the resulting mechanical properties are presented. The mechanical strength of the polyamide test bars increased with both increasing head speed and strip width. Increasing head speed would be desirable in microgravity applications.Mechanical Engineerin

FOOD REGULATION AND TRADE: TOWARD A SAFE AND OPEN GLOBAL SYSTEM -- AN OVERVIEW AND SYNOPSIS

A synopsis is presented of challenges faced and WTO performance in disciplining national technical measures to achieve legitimate objectives in a least-trade-distorting manner. Importance of the measures and international disciplines are reviewed and evidence presented from multiple perspectives that suggests a limited constructive WTO role.International Relations/Trade,

TECHNICAL BARRIERS IN THE GLOBAL POULTRY MARKET: A SEARCH FOR 'MISSING TRADE'

This paper was presented at the INTERNATIONAL TRADE IN LIVESTOCK PRODUCTS SYMPOSIUM in Auckland, New Zealand, January 18-19, 2001. The Symposium was sponsored by: the International Agricultural Trade Research Consortium, the Venture Trust, Massey University, New Zealand, and the Centre for Applied Economics and Policy Studies, Massey University. Dietary changes, especially in developing countries, are driving a massive increase in demand for livestock products. The objective of this symposium was to examine the consequences of this phenomenon, which some have even called a "revolution." How are dietary patterns changing, and can increased demands for livestock products be satisfied from domestic resources? If so, at what cost? What will be the flow-on impacts, for example, in terms of increased demands for feedgrains and the pressures for change within marketing systems? A supply-side response has been the continued development of large-scale, urban-based industrial livestock production systems that in many cases give rise to environmental concerns. If additional imports seem required, where will they originate and what about food security in the importing regions? How might market access conditions be re-negotiated to make increased imports achievable? Other important issues discussed involved food safety, animal health and welfare and the adoption of biotechnology, and their interactions with the negotiation of reforms to domestic and trade policies. Individual papers from this conference are available on AgEcon Search. If you would like to see the complete agenda and set of papers from this conference, please visit the IATRC Symposium web page at: http://www1.umn.edu/iatrc.intro.htmInternational Relations/Trade,

A Framework for Analyzing Technical Trade Barriers in Agricultural Markets

Technical trade barriers are increasingly important in the international trade of agricultural products. Designing technical trade measures that can satisfy the growing demand for food safety, product differentiation, environmental amenities, and product information at the lowest cost to the consumer and to the international trading system requires an understanding of the complex economics of regulatory import barriers. This report proposes a definition and classification scheme to frame discussion and evaluation of such measures. Open-economy models that complement the classification scheme are developed graphically to highlight the basic elements that affect the economic impacts of changes in technical trade barriers.technical trade barriers, sanitary and phytosanitary, agricultural trade policy, environmental trade measures, International Relations/Trade,

Kinematic dynamo action in a sphere. I. Effects of differential rotation and meridional circulation on solutions with axial dipole symmetry

A sphere containing electrically conducting fluid can generate a magnetic field by dynamo action, provided the flow is sufficiently complicated and vigorous. The dynamo mechanism is thought to sustain magnetic fields in planets and stars. The kinematic dynamo problem tests steady flows for magnetic instability, but rather few dynamos have been found so far because of severe numerical difficulties. Dynamo action might, therefore, be quite unusual, at least for large-scale steady flows. We address this question by testing a two-parameter class of flows for dynamo generation of magnetic fields containing an axial dipole. The class of flows includes two completely different types of known dynamos, one dominated by differential rotation (D) and one with none. We find that 36% of the flows in seven distinct zones in parameter space act as dynamos, while the remaining 64% either fail to generate this type of magnetic field or generate fields that are too small in scale to be resolved by our numerical method. The two previously known dynamo types lie in the same zone, and it is therefore possible to change the flow continuously from one to the other without losing dynamo action. Differential rotation is found to promote large-scale axisymmetric toroidal magnetic fields, while meridional circulation (M) promotes large-scale axisymmetric poloidal fields concentrated at high latitudes near the axis. Magnetic fields resembling that of the Earth are generated by D > 0, corresponding to westward flow at the surface, and M of either sign but not zero. Very few oscillatory solutions are found

Stair-case in the north trancept, Cathedral of Burgos [Material gráfico]

Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-201

History of the Innovation of Damage Control for Management of Trauma Patients: 1902-2016

Objective: To review the history of the innovation of damage control (DC) for management of trauma patients. Background: DC is an important development in trauma care that provides a valuable case study in surgical innovation. Methods: We searched bibliographic databases (1950-2015), conference abstracts (2009-2013), Web sites, textbooks, and bibliographies for articles relating to trauma DC. The innovation of DC was then classified according to the Innovation, Development, Exploration, Assessment, and Long-term study model of surgical innovation. Results: The innovation\u27\u27 of DC originated from the use of therapeutic liver packing, a practice that had previously been abandoned after World War II because of adverse events. It then developed\u27\u27 into abbreviated laparotomy using rapid conservative operative techniques.\u27\u27 Subsequent exploration\u27\u27 resulted in the application of DC to increasingly complex abdominal injuries and thoracic, peripheral vascular, and orthopedic injuries. Increasing use of DC laparotomy was followed by growing reports of postinjury abdominal compartment syndrome and prophylactic use of the open abdomen to prevent intra-abdominal hypertension after DC laparotomy. By the year 2000, DC surgery had been widely adopted and was recommended for use in surgical journals, textbooks, and teaching courses ( assessment\u27\u27 stage of innovation). Long-term study\u27\u27 of DC is raising questions about whether the procedure should be used more selectively in the context of improving resuscitation practices. Conclusions: The history of the innovation of DC illustrates how a previously abandoned surgical technique was adapted and readopted in response to an increased understanding of trauma patient physiology and changing injury patterns and trauma resuscitation practices

Bringing Entrepreneurial Ideas to Life

Organizational design in the context of new venture development is particularly challenging due to initially severe resource constraints. Deepening our understanding of differential productivity in the startup resource assembly process is therefore important. We address the twin questions of what assets are important to venture performance, and under what conditions are those assets especially important? We do so by considering initial venture idea assets and founder contracting experience. The resource-based view of the firm stresses developing the right assets, which accords with idea assets. Firm boundary theories of the firm emphasize structuring relationships in the right way given a set of organizational assets, which accords with founder contracting experience. Using unique survey data, we find that neither view by itself is as important as both theories taken together. We therefore advance an integrated perspective by showing that new ventures perform better when they both identify valuable resources and also assemble human assets with expertise in structuring organizational arrangements to commercialize those ideas. An important implication is that organizational resources have a range of potential values, and that realizing the upper range of value capture involves the additional ability to structure organizational relationships.We gratefully acknowledge funding from the Ewing Marion Kauffman Foundation, the M.I.T. Entrepreneurship Center, and the Alfred P. Sloan Foundation under the Industry Studies Program

Glory Oscillations in the Index of Refraction for Matter-Waves

We have measured the index of refraction for sodium de Broglie waves in gases of Ar, Kr, Xe, and nitrogen over a wide range of sodium velocities. We observe glory oscillations -- a velocity-dependent oscillation in the forward scattering amplitude. An atom interferometer was used to observe glory oscillations in the phase shift caused by the collision, which are larger than glory oscillations observed in the cross section. The glory oscillations depend sensitively on the shape of the interatomic potential, allowing us to discriminate among various predictions for these potentials, none of which completely agrees with our measurements

Diffuse HI Disks in Isolated Galaxies

In order to investigate the contribution of diffuse components to their total HI emission, we have obtained high precision HI line flux densities with the 100m Green Bank Telescope for a sample of 100 isolated spiral and irregular galaxies which we have previously observed with the 43m telescope. A comparison of the observed HI line fluxes obtained with the two different telescopes, characterized by half-power beam widths of 9 arcmin and 21 arcmin respectively, exploits a ``beam matching'' technique to yield a statistical determination of the occurrence of diffuse HI components in their disks. A simple model of the HI distribution within a galaxy well describes ~75 % of the sample and accounts for all of the HI line flux density. The remaining galaxies are approximately evenly divided into two categories: ones which appear to possess a significantly more extensive HI distribution than the model predicts, and ones for which the HI distribution is more centrally concentrated than predicted. Examples of both extremes can be found in the literature but little attention has been paid to the centrally concentrated HI systems. Our sample has demonstrated that galaxies do not commonly possess extended regions of low surface brightness HI gas which is not accounted for by our current understanding of the structure of HI disks. Eight HI-rich companions to the target objects are identified, and a set of extragalactic HI line flux density calibrators is presented.Comment: 26 page