Unified Approach to the Biomechanics of Dental Implantology

The human need for safe and effective dental implants is well-recognized. Although many implant designs have been tested and are in use today, a large number have resulted in clinical failure. These failures appear to be due to biomechanical effects, as well as biocompatibility and surgical factors. A unified approach is proposed using multidisciplinary systems technology, for the study of the biomechanical interactions between dental implants and host tissues. The approach progresses from biomechanical modeling and analysis, supported by experimental investigations, through implant design development, clinical verification, and education of the dental practitioner. The result of the biomechanical modeling, analysis, and experimental phases would be the development of scientific design criteria for implants. Implant designs meeting these criteria would be generated, fabricated, and tested in animals. After design acceptance, these implants would be tested in humans, using efficient and safe surgical and restorative procedures. Finally, educational media and instructional courses would be developed for training dental practitioners in the use of the resulting implants

Radon: An Opportunity for Preventative Health

Radon is a colorless and odorless radioactive gas produced by the natural decay of uranium in rock and soil. Long term exposure to radon gas is the leading cause of lung cancer among non-smokers, and the second leading cause over all after smoking. Children exposed to unsafe levels of radon are particularly vulnerable because smaller lungs and faster respiratory rates are thought to result in higher radiation doses compared with adults. One in eight homes in Vermont contain unsafe levels of radon gas compared with one in fifteen homes nationally. Radon gas exposure is not currently addressed as a preventative health measure in primary care clinics. This intervention was aimed at creating a radon resource document embedded as a “smart phrase” in EPIC enabling clinicians to rapidly provide clear information for patients without encumbering time constrained appointments. The intent is to equip providers with a tool for introducing the topic of radon at pediatric well visits and give patients access to additional information included in their After Visit Summaries.https://scholarworks.uvm.edu/fmclerk/1469/thumbnail.jp

Communication Efficiency in Self-stabilizing Silent Protocols

Self-stabilization is a general paradigm to provide forward recovery capabilities to distributed systems and networks. Intuitively, a protocol is self-stabilizing if it is able to recover without external intervention from any catastrophic transient failure. In this paper, our focus is to lower the communication complexity of self-stabilizing protocols \emph{below} the need of checking every neighbor forever. In more details, the contribution of the paper is threefold: (i) We provide new complexity measures for communication efficiency of self-stabilizing protocols, especially in the stabilized phase or when there are no faults, (ii) On the negative side, we show that for non-trivial problems such as coloring, maximal matching, and maximal independent set, it is impossible to get (deterministic or probabilistic) self-stabilizing solutions where every participant communicates with less than every neighbor in the stabilized phase, and (iii) On the positive side, we present protocols for coloring, maximal matching, and maximal independent set such that a fraction of the participants communicates with exactly one neighbor in the stabilized phase

Mechanical Properties and Durability of a Composite Material at Cryogenic Temperatures

Several issues relevant to the use of a high-performance graphite-epoxy material in hydrogen storage tank applications have been examined. The tensile properties of IM7/977-2 were evaluated as a function of test temperature and thermal-mechanical load history. The temperature dependent coefficient of thermal expansion (CTE) of unidirectional specimens of the same material was measured between -200°C and 0°C. The effects of test temperature, mechanical loading, and damage state on the leak rate of hydrogen gas through IM7/977-2 laminates were evaluated using a novel test system. Finally, the mechanical properties of several commercially available polymer films, which might prove useful as leak-resistant liners for composite cryogenic fuel tanks, were evaluated at elevated and cryogenic temperatures. The mechanical property study of IM7/977-2 showed that the effects of exposure to a cryogenic fuel tank environment varied significantly with test temperature and laminate schedule. Matrix dominated properties were found to be the most strongly affected by cryogenic test temperature exposure. Fiber-dominated properties were found to be comparatively insensitive to cryogenic test temperature. The CTE measurements showed that the cryogenic conditioning did not have marked effects on the thermal expansion behavior of IM7/977-2. Transverse CTE was Coefficient of thermal expansion was calculated strongly temperature-dependent. The leak rate study revealed that both mechanical loading and decreasing test temperatures increase the leak rate of gaseous hydrogen through the microcrack network within a damaged composite laminate. The effect of temperature on permeability was shown to be stronger than that of tensile loading. At low damage levels, proportionality was demonstrated between the number of crack junctions present within the laminate and the hydrogen gas leak rate. At higher damage levels this proportionality was not as clear, perhaps due to the greater role played by delaminations in gas leakage. In the polymer film study, large differences were observed in tensile modulus and tensile strength at 23°C and 65°C. At -150°C, the differences were far smaller and the behavior of all of the films was uniformly brittle in nature

Automated Fiber Placement of Composite Wind Tunnel Blades: Process Planning and Manufacturing

The ability to accurately manufacture large complex shapes in a consistent and repeatable manner has led to Automated Fiber Placement (AFP) being the predominant mode of manufacturing for large composite aerospace structures today. Currently, AFP is being considered for medium- and small-scale parts. Composite wind tunnel blades have traditionally been fabricated by hand layup for pre-impregnated or dry fabrics with resin infusion. Though well proven, the traditional fabrication method is laborious and tedious, and hence expensive. The project described in this paper used the Integral Structural Assembly of Advanced Composites (ISAAC) facility at the NASA Langley Research Center to build a manufacturing demonstration unit (MDU) with a shape representative of a wind tunnel blade. This MDU is used to discuss tooling, process planning, and fabrication. Additionally, details of the generic manufacturing workflow are presented

Assessment of Automated Fiber Placement for the Fabrication of Composite Wind Tunnel Blades

Composite wind tunnel blades are frequently fabricated by hand layup of prepreg fabrics. Though well proven, this fabrication method is laborious and expensive. The study described in this paper used the Integrated Structural Assembly of Advanced Composites (ISAAC) facility at the NASA Langley Research Center to explore whether automated fiber placement (AFP) could reduce manufacturing time and cost for production of wind tunnel blades. Two blades, taken from two NASA wind tunnels, were investigated as representative geometries. Computer-aided design models of the blade surfaces were created, and AFP process planning and programming were employed to study the manufacturability of the shapes. A placement/cure tool was manufactured for the chosen blade surface from thermoplastic material using an additive manufacturing process. The present study revealed that the AFP head geometry, primarily the heater configuration of the ISAAC system, is the primary constraint that limits the ability to manufacture the selected wind tunnel fan blades using AFP

An Interdisciplinary Approach to Documenting Knowledge: Plants and Their Uses in Southern Greenland

Local Greenlanders assume that traditional knowledge of plant uses in Greenland has been lost due to extensive Danish contact and modernization. We used an interdisciplinary approach to reconstruct this lost knowledge: the biologist provided botanical identification, plant uses, methods of collection, preparation, and storage, while the linguist provided access to the linguistic identification of the plants, both in Greenland and in a pan-Inuit context, and access to the historical documentation. We conducted open-ended and semi-structured interviews at two sites in South Greenland to document plant names and uses. Our findings indicate that local knowledge of is greater than believed. We documented over 170 uses of plants, mosses, fungi, and seaweeds. Here we consider the meaning and etymologies of Kalaallisut plant names, how they correspond or differ to other Inuit terminology, and compare traditional uses with those from other Arctic peoples to identify traditional Inuit knowledge versus that influenced by Danish contact. Certain medicinal plants appear to be known across the Arctic but differ in preparation between peoples. Some uses are clearly derived from Danish culinary practices. From a linguistic standpoint plant names appear to be derived from the Inuit language family. These data demonstrate the fusion of traditional and colonialist knowledge

An Interdisciplinary Approach to Documenting Knowledge: Plants and Their Uses in Southern Greenland

The native language of west Greenland, Kalaallisut, is robust, with over 50 000 speakers among approximately 56 000 inhabitants. However, many people in Nuuk, the capital and largest city, believe traditional knowledge of plant uses has been lost as a result of extensive Danish contact. Our findings indicate that in southern Greenland local knowledge of plant uses is greater than believed. Interviews conducted with people in two southern communities, Nanortalik and Qassiarsuk, showed that people acquire knowledge about plants through a vast number of resources, not only Inuit knowledge from elders, but also published European sources and experimentation, raising questions about the extent to which such knowledge can be labeled traditional or ancestral. We documented more than 50 taxa and 205 plant uses in seven broad categories: medicine, beverages, food, herbs and spices, fuel, ritual, and material culture, the last category consisting primarily of decorative uses. Although medicinal uses account for the largest amount (~27%), the combination of the food, beverage, and herbs and spices/condiment categories make up nearly half of all uses. Some plants, in particular mushrooms and seaweed, were identified as edible but are not consumed. All consultants are fluent speakers of Kalaallisut, and identified the majority of plants. However, only 12 species were identified by everyone consulted, and some plants were identified by their Danish name. Some plant names and uses have remained consistent along the migration route of Inuit ancestors across the Arctic, while others have been lost or changed over time.La langue autochtone de l’ouest du Groenland, le kalaallisut, est une langue robuste. Elle est parlée par plus de 50 000 personnes relevant d’une population d’environ 56 000 habitants. Cependant, de nombreuses personnes de Nuuk, la capitale et également la plus grande ville du pays, croient que les connaissances traditionnelles des plantes se sont perdues en raison des contacts trop grands avec les Danois. Nos observations indiquent cependant que dans le sud du Groenland, la connaissance des plantes locales est meilleure que ce que les gens croient. Des entrevues réalisées auprès de gens faisant partie de deux collectivités du Sud, Nanortalik et Qassiarsuk, montrent que les gens acquièrent des connaissances au sujet des plantes au moyen de diverses sources, non seulement les aînés inuits, mais aussi à partir de sources européennes publiées et d’expérimentation, ce qui a pour effet de soulever des questions à savoir dans quelle mesure les connaissances peuvent être considérées comme traditionnelles ou ancestrales. Nous avons répertorié plus de 50 taxons et de 205 utilisations de plantes relevant de sept grandes catégories : médecine, boissons, aliments, herbes et épices, carburants, rituels et culture matérielle. Cette dernière catégorie prend principalement la forme d’usages décoratifs. Bien que les utilisations à caractère médicinal représentent la plus grande partie des utilisations (~27 %), l’ensemble des catégories des aliments, des boissons et des herbes et épices-condiments représente près de la moitié de tous les usages. Certaines plantes, plus particulièrement les champignons et les algues, étaient considérées comme comestibles, sans pour autant être consommées. Toutes les personnes consultées parlent le kalaallisut couramment, et elles ont réussi à identifier la majorité des plantes. Toutefois, seulement 12 espèces ont été identifiées par toutes les personnes consultées, et certaines plantes ont été identifiées au moyen de leur nom danois. Le nom et l’utilisation de certaines plantes sont restés les mêmes le long de la route de migration des ancêtres inuits à l’échelle de l’Arctique, tandis que d’autres se sont perdus ou ont été modifiés au fil du temps.Mots clés : Groenland, Arctique, ethnobotanique, linguistique, langue, Inuit, connaissance locale, plante