92 research outputs found

    Cuprous oxide rectification

    Get PDF
    It has been shown that cuprous oxide, when formed from a copper surface by suitable heat treatment, has remarkable rectifying properties towards alternating voltages applied through the oxide and copper. The purpose of our work was to investigate, the effect fully from all angles possible, and especially from those considerations affecting the constancy and permanence in the electric circuit. The work ranged from furnace operation to tests of completed units, and further to the development of a theory explaining as completely as possible this rectifying property. It soon became apparent, that here was ideal thesis material, and so, with proper permission, I have undertaken this rather complete report and now offer it as my thesis. The work was carried on jointly by Mr. Rutger B. Colt, of Stevens Institute, Mr. Charles H. Bartlett of Brooklyn Polytechnic Institute, and myself. In all a period of one year and three months was devoted to this investigation, and during that time we all were largely employed directly, although other matters claimed attention occasionally

    Functional tests of the competitive exclusion hypothesis for multituberculate extinction

    Get PDF
    Multituberculate mammals thrived during the Mesozoic, but their diversity declined from the mid-late Paleocene onwards, becoming extinct in the late Eocene. The radiation of superficially similar, eutherian rodents has been linked to multituberculate extinction through competitive exclusion. However, characteristics providing rodents with a supposed competitive advantage are currently unknown and comparative functional tests between the two groups are lacking. Here, a multifaceted approach to craniomandibular biomechanics was taken to test the hypothesis that superior skull function made rodents more effective competitors. Digital models of the skulls of four extant rodents and the Upper Cretaceous multituberculate Kryptobaatar were constructed and used (i) in finite-element analysis to study feeding-induced stresses, (ii) to calculate metrics of bite force production and (iii) to determine mechanical resistances to bending and torsional forces. Rodents exhibit higher craniomandibular stresses and lower resistances to bending and torsion than the multituberculate, apparently refuting the competitive exclusion hypothesis. However, rodents optimize bite force production at the expense of higher skull stress and we argue that this is likely to have been more functionally and selectively important. Our results therefore provide the first functional lines of evidence for potential reasons behind the decline of multituberculates in the changing environments of the Paleogene.Peer reviewe

    Explorations, Vol. 2, No. 1

    Get PDF
    Cover: The painting reproduced on the cover is a 22” by 30” acrylic on paper entitled Passage-10, by James Linehan, Assistant Professor of Art at the University of Maine at Orono, where he teaches painting. ©James Linehan, 1985. Articles include: Polyunsaturated Fats: are they killing us? by Linda J. Kling Where are the Dreamers: aspirations of Maine\u27s rural high school students, by Robert A. Cobb, Walter G. McIntire, and Philip A. Pratt Elsewhere in Education: a research sampler \u22Physical Education and Handicapped Children, Stephen A. Butterfield School Climate and Teacher Efficacy, Theodore Coadarci The Principal Principle, Gordon A. Donaldson, Jr. Assessing Leadership, Ronald L. Sparkes Malnutrition in Maine, by Richard A. Cook Hypertension: aging and intellect, by Merrill F. Elias and Michael Robbins From Campus to Public Schools A Ceiling on Shelter, by Peggy K. Schomaker From the Dispatch Case: Control of Cell Growth at the Level of the Genetic Code, by R.D. Blake In the Spring issue of EXPLORATIONS: The sure but silent force in American foreign policy in post World War II Japan—Harry F. Ker

    How to Get the Most out of Your Curation Effort

    Get PDF
    Large-scale annotation efforts typically involve several experts who may disagree with each other. We propose an approach for modeling disagreements among experts that allows providing each annotation with a confidence value (i.e., the posterior probability that it is correct). Our approach allows computing certainty-level for individual annotations, given annotator-specific parameters estimated from data. We developed two probabilistic models for performing this analysis, compared these models using computer simulation, and tested each model's actual performance, based on a large data set generated by human annotators specifically for this study. We show that even in the worst-case scenario, when all annotators disagree, our approach allows us to significantly increase the probability of choosing the correct annotation. Along with this publication we make publicly available a corpus of 10,000 sentences annotated according to several cardinal dimensions that we have introduced in earlier work. The 10,000 sentences were all 3-fold annotated by a group of eight experts, while a 1,000-sentence subset was further 5-fold annotated by five new experts. While the presented data represent a specialized curation task, our modeling approach is general; most data annotation studies could benefit from our methodology

    Developing nanotechnology in Latin America

    Get PDF
    This article investigates the development of nanotechnology in Latin America with a particular focus on Argentina, Brazil, Chile, and Uruguay. Based on data for nanotechnology research publications and patents and suggesting a framework for analyzing the development of R&D networks, we identify three potential strategies of nanotechnology research collaboration. Then, we seek to identify the balance of emphasis upon each of the three strategies by mapping the current research profile of those four countries. In general, we find that they are implementing policies and programs to develop nanotechnologies but differ in their collaboration strategies, institutional involvement, and level of development. On the other hand, we find that they coincide in having a modest industry participation in research and a low level of commercialization of nanotechnologies

    Social support and social structure

    Full text link
    The burgeoning study of social support in relation to social stress and health would benefit from increased attention to issues of social structure. Three aspects of social relationships, all often referred to as social support, must be more clearly distinguished—(1) their existence or quantity (i.e., social integration), (2) their formal structure (i.e., social networks), and (3) their functional or behavioral content (i.e., the most precise meaning of “social support”)—and the causal relationships between the structure of social relationships (social integration and networks) and their functional content (social support) must be more clearly understood. Research and theory are needed on the determinants of social integration, networks, and support as well as their consequences for stress and health. Among potential determinants, macrosocial structures and processes particularly merit attention.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45658/1/11206_2005_Article_BF01107897.pd

    BHPR research: qualitative1. Complex reasoning determines patients' perception of outcome following foot surgery in rheumatoid arhtritis

    Get PDF
    Background: Foot surgery is common in patients with RA but research into surgical outcomes is limited and conceptually flawed as current outcome measures lack face validity: to date no one has asked patients what is important to them. This study aimed to determine which factors are important to patients when evaluating the success of foot surgery in RA Methods: Semi structured interviews of RA patients who had undergone foot surgery were conducted and transcribed verbatim. Thematic analysis of interviews was conducted to explore issues that were important to patients. Results: 11 RA patients (9 ♂, mean age 59, dis dur = 22yrs, mean of 3 yrs post op) with mixed experiences of foot surgery were interviewed. Patients interpreted outcome in respect to a multitude of factors, frequently positive change in one aspect contrasted with negative opinions about another. Overall, four major themes emerged. Function: Functional ability & participation in valued activities were very important to patients. Walking ability was a key concern but patients interpreted levels of activity in light of other aspects of their disease, reflecting on change in functional ability more than overall level. Positive feelings of improved mobility were often moderated by negative self perception ("I mean, I still walk like a waddling duck”). Appearance: Appearance was important to almost all patients but perhaps the most complex theme of all. Physical appearance, foot shape, and footwear were closely interlinked, yet patients saw these as distinct separate concepts. Patients need to legitimize these feelings was clear and they frequently entered into a defensive repertoire ("it's not cosmetic surgery; it's something that's more important than that, you know?”). Clinician opinion: Surgeons' post operative evaluation of the procedure was very influential. The impact of this appraisal continued to affect patients' lasting impression irrespective of how the outcome compared to their initial goals ("when he'd done it ... he said that hasn't worked as good as he'd wanted to ... but the pain has gone”). Pain: Whilst pain was important to almost all patients, it appeared to be less important than the other themes. Pain was predominately raised when it influenced other themes, such as function; many still felt the need to legitimize their foot pain in order for health professionals to take it seriously ("in the end I went to my GP because it had happened a few times and I went to an orthopaedic surgeon who was quite dismissive of it, it was like what are you complaining about”). Conclusions: Patients interpret the outcome of foot surgery using a multitude of interrelated factors, particularly functional ability, appearance and surgeons' appraisal of the procedure. While pain was often noted, this appeared less important than other factors in the overall outcome of the surgery. Future research into foot surgery should incorporate the complexity of how patients determine their outcome Disclosure statement: All authors have declared no conflicts of interes
    corecore