A precision measurement of the lifetime of the positive muon

In an experiment performed at TRIUMF Laboratory, the time distribution of muon decay positrons arising from pions stopped in a water Cherenkov counter was measured with a high precision timing system. The pions served as a source of positive muons.;The data were used to determine a new value for the positive muon lifetime. This lifetime 2.19695 (+OR-) .00006 (sec) is slightly lower than previous measurements but still in fair agreement. The data were tested for the various systematic effects that typically occur in these measurements

Re-imagining Christian Education for Millennials in an African American Pentecostal Assemblies Context

It seems many Christian Pentecostal churches are struggling to disciple and retain a millennial population. According to a recent Gallup Poll, 57% of religious millennials have church membership, and this represents the lowest percentage among current generations as overall church membership and participation trends downward from 76% in 1948 to 52% in 2018 (Jones, 2019). The factors contributing to the poll must be explored both from outside and inside of the church. One may wonder if the church is providing the proper education and training to attract and retain millennials. The purpose of this qualitative exploratory case study research design will be to explore current pedagogical methodologies and ICT use in Christian education among pastors and teachers in the Gates of Heaven Assembly of Churches (GOHAOC) and to assess the current level of satisfaction with and participation in Christian education ministry activities of the GOHAOC among the millennial members of the church community. At this stage in the research, ICT is defined as a “diverse set of technological tools and resources used to communicate and to create, disseminate, store, and manage information. These technologies include computers, the Internet, broadcasting technologies (radio and television), and telephony” (Amin, 2018, p.2). Pastors, Christian educators, and millennials will be interviewed and surveyed to explore contributing factors to the target group\u27s discipleship practices. The qualitative methodology was chosen to analyze the practices surrounding the research problem. Research findings and recommendations from this research will contribute to the body of literature on discipling millennials

Taxes, Default Risk, and Yield Spreads

This paper represents an extension and integration of recent empirical and theoretical research on default risk and taxability. The purpose of the paper is to develop and test a model of interest rate spreads which incorporates both the effect of taxes and differences in default probabilities in a theoretically correct manner. There is an important fundamental difference between our approach to explaining yield spreads and the approach most commonly taken in literature. Unlike nearly all of the previous work, we do not begin with a yield spread model, i.e.,one which begins by examining differences in yields, but rather begin with an expected return or pricing model, which can then be expressed in the yield spread format. This is a fundamental difference in approaches which we feel leads to a superior theoretical formulation which can then be tested empirically without many of the problems inherent in the alter-native approach. The theoretical model is a simple extension of earlierwork on default by Bierman and Hass (1975) and Yawitz (1977), altered appropriately to take explicit account of tax effects. While there is a considerable literature that analyzes the effect of taxability on rate spreads, we are unaware of any previous study that considers tax consequences in the event of default, a rather surprising omission.

Evaluación in vitro del potencial neuroprotector de las células madre mesenquimales sobre los fotorreceptores

La degeneración de los fotorreceptores (FR) es un proceso en el cuál confluyen diversas enfermedades neurodegenerativas de la retina como son la degeneración macular asociada a edad o la retinitis pigmentosa. Enfermedades que representan unas de las principales causas de ceguera a nivel mundial ya que actualmente carecen de un tratamiento realmente efectivo. Las terapias avanzadas se muestran como una alternativa para el tratamiento de este tipo de patologías; entre ellas, la terapia celular mediada por factores paracrinos se perfila como la alternativa más viable. En este sentido, la utilización de células madre mesenquimales (MSCs) podría frenar la degeneración que sufren los FR retinianos en este tipo de patologías. Por ello éste trabajo se planteó el estudio inmunohistoquímico de los FR tras el cocultivo de la retina con las MSCs y el análisis del secretoma proteico tras el cocultivo. Los resultados del presente trabajo mostraron como las MSCs tenían la capacidad de frenar la neurodegeneración de la capa de FR de la retina. Lo que sugiere su posible futura aplicación en tratamientos de terapia celular destinados a pacientes que sufren distrofias retinianas que cursan con la degeneración de los FR. También se muestra como el efecto neuroprotector desarrollado por las MSCs se podría basar en la secreción de factores proteicos por parte de las MSCs, que estarían destinados a contrarrestar los procesos típicos de la degeneración retiniana. Todo ello sienta las bases para, en un futuro, elaborar terapias neuroprotectoras basadas en la combinación de factores neuroprotectores procedentes de las MSCs.Departamento de Cirugía, Oftalmología, Otorrinolaringología y FisioterapiaMáster en Investigación en Ciencias de la Visió

Deployment of a Curved Truss

Structures capable of deployment into complex, three-dimensional trusses have well known space technology applications such as the support of spacecraft payloads, communications antennas, radar reflectors, and solar concentrators. Such deployable trusses could also be useful in terrestrial applications such as the rapid establishment of structures in military and emergency service situations, in particular with regard to the deployment of enclosures for habitat or storage. To minimize the time required to deploy such an enclosure, a single arch-shaped truss is preferable to multiple straight trusses arranged vertically and horizontally. To further minimize the time required to deploy such an enclosure, a synchronous deployment with a single degree of freedom is also preferable. One method of synchronizing deployment of a truss is the use of a series of gears; this makes the deployment sequence predictable and testable, allows the truss to have a minimal stowage volume, and the deployed structure exhibits the excellent stiffness-to-mass and strength-to-mass ratios characteristic of a truss. A concept for using gears with varying ratios to deploy a truss into a curved shape has been developed and appears to be compatible with both space technology applications as well as potential use in terrestrial applications such as enclosure deployment. As is the case with other deployable trusses, this truss is formed using rigid elements (e.g., composite tubes) along the edges, one set of diagonal elements composed of either cables or folding/hinged rigid members, and the other set of diagonal elements formed by a continuous cable that is tightened by a motor or hand crank in order to deploy the truss. Gears of varying ratios are used to constrain the deployment to a single degree of freedom, making the deployment synchronous, predictable, and repeatable. The relative sizes of the gears and the relative dimensions of the diagonal elements determine the deployed geometry (e.g. curvature) of the truss

Dedicated Deployable Aerobraking Structure

A dedicated deployable aerobraking structure concept was developed that significantly increases the effective area of a spacecraft during aerobraking by up to a factor of 5 or more (depending on spacecraft size) without substantially increasing total spacecraft mass. Increasing the effective aerobraking area of a spacecraft (without significantly increasing spacecraft mass) results in a corresponding reduction in the time required for aerobraking. For example, if the effective area of a spacecraft is doubled, the time required for aerobraking is roughly reduced to half the previous value. The dedicated deployable aerobraking structure thus enables significantly shorter aerobraking phases, which results in reduced mission cost, risk, and allows science operations to begin earlier in the mission

Object-Oriented Modeling of Communication Systems

Conventional communication system simulation programs and packages are written using procedural programming languages. Newly developed, object-oriented languages offer the simulation designer significantly different options and structures. By exploiting these new techniques it is possible to significantly increase the flexibility and extensibility of the simulation package. This allows the system analyst to efficiently re-use complex simulation code and quickly and reliably reconfigure the simulation. In addition, a single object-oriented simulation can be used in all stages of the design process, from conceptual design through fabrication and testing. A final benefit of the object-oriented techniques is that the simulation code closely matches the graphical user interface used in most modern simulation packages. This work discusses the basic attributes of an object-oriented model and examines why this may be an attractive simulation architecture

A Bayesian approach for inferring the dynamics of partially observed endemic infectious diseases from space-time-genetic data

We describe a statistical framework for reconstructing the sequence of transmission events between observed cases of an endemic infectious disease using genetic, temporal and spatial information. Previous approaches to reconstructing transmission trees have assumed all infections in the study area originated from a single introduction and that a large fraction of cases were observed. There are as yet no approaches appropriate for endemic situations in which a disease is already well established in a host population and in which there may be multiple origins of infection, or that can enumerate unobserved infections missing from the sample. Our proposed framework addresses these shortcomings, enabling reconstruction of partially observed transmission trees and estimating the number of cases missing from the sample. Analyses of simulated datasets show the method to be accurate in identifying direct transmissions, while introductions and transmissions via one or more unsampled intermediate cases could be identified at high to moderate levels of case detection. When applied to partial genome sequences of rabies virus sampled from an endemic region of South Africa, our method reveals several distinct transmission cycles with little contact between them, and direct transmission over long distances suggesting significant anthropogenic influence in the movement of infected dogs

Vibrational fingerprint of the absorption properties of UiO-type MOF materials

The absorption properties of UiO-type metal-organic frameworks are computed using TD-DFT simulations on the organic linkers. A set of nine isoreticular structures, including the UiO-66 and UiO-67 materials and functionalized variants, are examined. The excitation energies from a static geometry optimization are compared with dynamic averages obtained from sampling the ground-state potential energy surface using molecular dynamics. The vibrational modes that impact the excitation energy are identified. This analysis is done using a recently proposed tool based on power spectra of the velocities and the excitation energies. The applied procedure allows including important factors influencing the absorption spectra, such as the periodic framework, linker variation and dynamical effects including harmonic and anharmonic nuclear motions. This methodology allows investigating in detail the vibrational fingerprint of the excitation energy of advanced materials such as MOFs and gives perspectives to tailor materials toward new light-based applications