Resolving the Issue of How Reliability is Related to Statistical Power: Adhering to Mathematical Definitions

Reliability in classical test theory is a population-dependent concept, defined as a ratio of true-score variance and observed-score variance, where observed-score variance is a sum of true and error components. On the other hand, the power of a statistical significance test is a function of the total variance, irrespective of its decomposition into true and error components. For that reason, the reliability of a dependent variable is a function of the ratio of true-score variance and observed-score variance, whereas statistical power is a function of the sum of the same two variances. Controversies about how reliability is related to statistical power often can be explained by authors’ use of the term “reliability” in a general way to mean “consistency,” “precision,” or “dependability,” which does not always correspond to its mathematical definition as a variance ratio. The present note shows how adherence to the mathematical definition can help resolve the issue and presents some derivations and illustrative examples that have further implications for significance testing and practical research

First Record and Habitat Notes for the Genus Lightiella (Crustacea, Cephalocarida, Hutchinsoniellidae) from the British Virgin Islands

The crustacean class Cephalocarida, as currently understood, is comprised of five genera and ten species (Hessler and Elofsson 1996, Hessler and Wakabara 2000). Although in some instances numerous specimens have been collected in a single locale (e.g., the nearly 120 specimens of Lightiella incisa Gooding, 1963 from Puerto Rico studied by Sanders and Hessler (1964), and the numerous specimens of Hutchinsoniella macracantha Sanders, 1955 now known from Buzzards Bay, Massachusetts, see Hessler and Sanders 1973:193), most reports are based on very few specimens. For example, the original description of the genus Hutchinsoniella Sanders, 1955 was based on only eight specimens from Long Island Sound, New York (Sanders 1955); the genus Sandersiella was originally described by Shiino (1965) on the basis of only one specimen from Japan; the genus Chiltoniella Knox and Fenwick, 1977 was based on two specimens from New Zealand (Knox and Fenwick 1977), and the genus Lightiella Jones, 1961 was based on seven specimens from San Francisco Bay (Jones 1961). Lightiella moniotae was described for a single individual from New Caledonia (Cals and Delamare-Deboutteville 1970); Sandersiella calmani for two specimens from Peru (Hessler and Sanders 1973); and Sandersiella bathyalis for two specimens from the deep ocean off southwest Africa (Hessler and Sanders 1973). The single eastern Caribbean record (Barbados) of a cephalocarid also was based on two specimens (Gooding 1963), although Gooding also discussed two specimens from Puerto Rico in that account. Cephalocarids are of such interest morphologically and phylogenetically, and are found so infrequently, that their presence anywhere is noteworthy. As part of an ongoing survey of the cryptic marine invertebrates of certain Caribbean islands, we obtained a single specimen of a cephalocarid from Guana Island, British Virgin Islands, that matches most closely the description by Gooding (1963) of L. incisa. The find is of interest not only because it is the first record for the far eastern Caribbean other than Gooding’s (1963) two type specimens from Barbados, but also because of the unusual habitat in which it was found

Project Cerberus: Flyby Mission to Pluto

The goal of the Cerberus Project was to design a feasible and cost-effective unmanned flyby mission to Pluto. The requirements in the request for proposal for an unmanned probe to Pluto are presented and were met. The design stresses proven technology that will avoid show stoppers which could halt mission progress. Cerberus also utilizes the latest advances in the spacecraft industry to meet the stringent demands of the mission. The topics covered include: (1) mission management, planning, and costing; (2) structures; (3) power and propulsion; (4) attitude, articulation, and control; (5) command, control, and communication; and (6) scientific instrumentation

Twinsol: A dual superconducting solenoid system for low-energy radioactive nuclear beam research

A unique type of apparatus is currently under construction as part of an upgrade to the radioactive ion beam facility at the University of Notre Dame Nuclear Structure Laboratory. The device will consist of a pair of large in-line superconducting solenoids (B0 = 6 tesla,B0=6tesla, bore=30 cmbore=30cm) which will be used to produce, collect, transport, focus and analyze both stable and radioactive nuclear beams. This apparatus in conjunction with the recently upgraded accelerators at Notre Dame is especially well suited for the production and utilization of intense (viz. >106/sec>106/sec), low-energy (1–10 MeV/u), stable and radioactive nuclear beams relevant to the study of reactions involved in astrophysical processes. These improvements will allow for the production of radioactive beams of greater intensity, higher purity and at both higher and lower energies than previously available at this facility. The first phase of construction and results of initial tests will be reported. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87534/2/397_1.pd

Molecular Dynamics Studies of Dislocations in CdTe Crystals from a New Bond Order Potential

Cd1-xZnxTe (CZT) crystals are the leading semiconductors for radiation detection, but their application is limited by the high cost of detector-grade materials. High crystal costs primarily result from property non-uniformity that causes low manufacturing yield. While tremendous efforts have been made in the past to reduce Te inclusions / precipitates in CZT, this has not resulted in an anticipated improvement in material property uniformity. Moreover, it is recognized that in addition to Te particles, dislocation cells can also cause electric field perturbation and the associated property non-uniformity. Further improvement of the material, therefore, requires that dislocations in CZT crystals be understood and controlled. Here we use a recently developed CZT bond order potential to perform representative molecular dynamics simulations to study configurations, energies, and mobilities of 29 different types of possible dislocations in CdTe (i.e., x = 1) crystals. An efficient method to derive activation free energies and activation volumes of thermally activated dislocation motion will be explored. Our focus gives insight into understanding important dislocations in the material, and gives guidance toward experimental efforts for improving dislocation network structures in CZT crystals

In-reach specialist nursing teams for residential care homes : uptake of services, impact on care provision and cost-effectiveness

Background: A joint NHS-Local Authority initiative in England designed to provide a dedicated nursing and physiotherapy in-reach team (IRT) to four residential care homes has been evaluated.The IRT supported 131 residents and maintained 15 'virtual' beds for specialist nursing in these care homes. Methods: Data captured prospectively (July 2005 to June 2007) included: numbers of referrals; reason for referral; outcome (e.g. admission to IRT bed, short-term IRT support); length of stay in IRT; prevented hospital admissions; early hospital discharges; avoided nursing home transfers; and detection of unrecognised illnesses. An economic analysis was undertaken. Results: 733 referrals were made during the 2 years (range 0.5 to 13.0 per resident per annum)resulting in a total of 6,528 visits. Two thirds of referrals aimed at maintaining the resident's independence in the care home. According to expert panel assessment, 197 hospital admissions were averted over the period; 20 early discharges facilitated; and 28 resident transfers to a nursing home prevented. Detection of previously unrecognised illnesses accounted for a high number of visits. Investment in IRT equalled £44.38 per resident per week. Savings through reduced hospital admissions, early discharges, delayed transfers to nursing homes, and identification of previously unrecognised illnesses are conservatively estimated to produce a final reduction in care cost of £6.33 per resident per week. A sensitivity analysis indicates this figure might range from a weekly overall saving of £36.90 per resident to a 'worst case' estimate of £2.70 extra expenditure per resident per week. Evaluation early in implementation may underestimate some cost-saving activities and greater savings may emerge over a longer time period. Similarly, IRT costs may reduce over time due to the potential for refinement of team without major loss in effectiveness. Conclusion: Introduction of a specialist nursing in-reach team for residential homes is at least cost neutral and, in all probability, cost saving. Further benefits include development of new skills in the care home workforce and enhanced quality of care. Residents are enabled to stay in familiar surroundings rather than unnecessarily spending time in hospital or being transferred to a higher dependency nursing home setting

Randomized Trial on the 5 a Day, the Rio Grande Way Website, A Web-based Program to Improve Fruit and Vegetable Consumption in Rural Communities

The Internet is a new technology for health communication in communities. The 5 a Day, the Rio Grande Way website intended to increase fruits and vegetables (FV) consumption was evaluated in a rural region enrolling 755 adults (65% Hispanic, 9% Native American, 88% female) in a randomized pretest–posttest controlled trial in 2002–2004. A total of 473 (63%) adults completed a 4-month follow-up. The change in daily intake on a food frequency questionnaire (control: mean = − 0.26 servings; intervention: mean = 0.38; estimated difference = 0.64, SD = 0.52, t(df = 416) = 1.22, p = 0.223) and single item (13.9% eating 5+ servings at pretest, 19.8% posttest for intervention; 17.4%, 13.8% for controls; odds ratio (OR) = 1.84, 95% CI = 1.07, 3.17) was in the expected direction but significant only for the single item. Website use was low and variable (logins: M = 3.3, range = 1 to 39.0; total time: M = 22.2 minutes, range = 0 to 322.7), but it was associated positively with fruit and vegetable intake (total time: Spearman r = 0.14, p = 0.004 for food frequency; Spearman r = 0.135, p = 0.004 for single item). A nutrition website may improve FV intake. The comparison on the food frequency measure may have been undermined by its high variability. Websites may be successful in community settings only when they are used enough by adults to influence them

O impacto, sobre estudantes brasileiros, de uma linguagem visual para aprender a aprender conjuntamente

Resumo Um dos temas mais importantes na aprendizagem colaborativa apoiada pelo computador é a autorregulação da aprendizagem sem o apoio de professores. A autorregulação da colaboração pode ser definida como o conjunto dos processos sociais que os alunos usam para coordenar o seu esforço conjunto em uma atividade. Este trabalho apresenta um estudo de caso brasileiro que examina o impacto da plataforma computacional Metafora para apoiar a regulação da colaboração entre os estudantes brasileiros. Nosso objetivo é investigar se o uso da linguagem visual Metafora ajuda os alunos a aprenderem a aprender em conjunto (learn to learn togueter – L2L2). L2L2 abrange o desenvolvimento da capacidade de coordenação da colaboração. Para perseguir esse objetivo, são fornecidas evidências de mecanismos de coordenação e as respostas emocionais subjacentes ao uso, pelos alunos, da ferramenta de planejamento Metafora. Os resultados deste estudo de caso demonstram que as interações dos alunos, ao usarem a ferramenta de planejamento Metafora, influenciaram o seu desenvolvimento de L2L2 de maneira natural e envolvente. A ferramenta de planejamento Metafora proporciona aos alunos um ambiente amigável para a regulação dos processos de grupo e tem potencial para modificar os pensamentos dos estudantes com respeito à coordenação de processos colaborativos

In quest of a systematic framework for unifying and defining nanoscience

This article proposes a systematic framework for unifying and defining nanoscience based on historic first principles and step logic that led to a “central paradigm” (i.e., unifying framework) for traditional elemental/small-molecule chemistry. As such, a Nanomaterials classification roadmap is proposed, which divides all nanomatter into Category I: discrete, well-defined and Category II: statistical, undefined nanoparticles. We consider only Category I, well-defined nanoparticles which are >90% monodisperse as a function of Critical Nanoscale Design Parameters (CNDPs) defined according to: (a) size, (b) shape, (c) surface chemistry, (d) flexibility, and (e) elemental composition. Classified as either hard (H) (i.e., inorganic-based) or soft (S) (i.e., organic-based) categories, these nanoparticles were found to manifest pervasive atom mimicry features that included: (1) a dominance of zero-dimensional (0D) core–shell nanoarchitectures, (2) the ability to self-assemble or chemically bond as discrete, quantized nanounits, and (3) exhibited well-defined nanoscale valencies and stoichiometries reminiscent of atom-based elements. These discrete nanoparticle categories are referred to as hard or soft particle nanoelements. Many examples describing chemical bonding/assembly of these nanoelements have been reported in the literature. We refer to these hard:hard (H-n:H-n), soft:soft (S-n:S-n), or hard:soft (H-n:S-n) nanoelement combinations as nanocompounds. Due to their quantized features, many nanoelement and nanocompound categories are reported to exhibit well-defined nanoperiodic property patterns. These periodic property patterns are dependent on their quantized nanofeatures (CNDPs) and dramatically influence intrinsic physicochemical properties (i.e., melting points, reactivity/self-assembly, sterics, and nanoencapsulation), as well as important functional/performance properties (i.e., magnetic, photonic, electronic, and toxicologic properties). We propose this perspective as a modest first step toward more clearly defining synthetic nanochemistry as well as providing a systematic framework for unifying nanoscience. With further progress, one should anticipate the evolution of future nanoperiodic table(s) suitable for predicting important risk/benefit boundaries in the field of nanoscience