5,702 research outputs found
Experiential knowledge as decision-making factor in international construction business
Abstract Operating on the foreign market poses a significant effort for construction firm that cannot be over sighted. During the preparation period, standard data collected prove to be insufficient leaving experiential reasoning to be a main factor for making a decision. Authors examine to question experiential knowledge according to institutional theory guidelines. Institutional theory is used as theoretical base which authors recognize as most comprehensive characterization of market context to date. On basis of a survey results authors bring conclusion that help uncover the nature of the experiential knowledge as a phenomeno
Supply chain strategy in post-earthquake Haiti
Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. [41]-[42]).Introduction: Partners In Health (PIH) is an international, non-profit healthcare organization with operations in several countries on multiple continents. PIH focuses on providing healthcare treatment to people living in some of the poorest places in the world, and has been operating in Haiti since 1985. At that time, PIH established a small community clinic in the central Haiti village of Cange. Today that facility has grown to become an entire medical complex, featuring a 104-bed, full-service hospital with two operating rooms, adult and pediatric wards, and clinics treating a variety of diseases and issues, from women's health to infectious diseases. In addition, Zamni Lasante ("Partners In Health" in Haitian Creyeol) has also expanded its operations to 11 other sites across Haiti's Central Plateau and beyond (Figure 1). Today, ZL ranks as one of the largest nongovernmental health care providers in Haiti - serving a catchment area of 1.2 million across the Central Plateau and the Lower Artibonite. ZL employs over 4,000 people, almost all of them Haitians, including doctors, nurses and community health workers (Zamni Lasante/ Haiti). From its beginnings 25 years ago, PIH/ZL has grown tremendously, and recent years have been no exception. Since 2004, patient encounters have increased almost threefold, from 0.9 million to 2.6 million, and the number of clinical sites has almost doubled. This growth has corresponded to an increase in drugs and supplies. In 2006, approximately 1000 m3 of drugs and supplies were moved through the system. Only two years later, in 2008, that number had more than doubled to 2200 m3 . This significant increase has greatly strained the underlying supply chain.by Scott C. Alexander.M.Eng.in Logistic
Characteristics of ferroelectric-ferroelastic domains in N{\'e}el-type skyrmion host GaVS
GaVS is a multiferroic semiconductor hosting N{\'e}el-type magnetic
skyrmions dressed with electric polarization. At T = 42K, the compound
undergoes a structural phase transition of weakly first-order, from a
non-centrosymmetric cubic phase at high temperatures to a polar rhombohedral
structure at low temperatures. Below T, ferroelectric domains are formed
with the electric polarization pointing along any of the four axes. Although in this material the size and the shape of the
ferroelectric-ferroelastic domains may act as important limiting factors in the
formation of the N{\'e}el-type skyrmion lattice emerging below T=13\:K, the
characteristics of polar domains in GaVS have not been studied yet.
Here, we report on the inspection of the local-scale ferroelectric domain
distribution in rhombohedral GaVS using low-temperature piezoresponse
force microscopy. We observed mechanically and electrically compatible lamellar
domain patterns, where the lamellae are aligned parallel to the (100)-type
planes with a typical spacing between 100 nm-1.2 m. We expect that the
control of ferroelectric domain size in polar skyrmion hosts can be exploited
for the spatial confinement and manupulation of N{\'e}el-type skyrmions
Valley degeneracy in biaxially strained aluminum arsenide quantum wells
This paper details a complete formalism for calculating electron subband
energy and degeneracy in strained multi-valley quantum wells grown along any
orientation with explicit results for the AlAs quantum well case. A
standardized rotation matrix is defined to transform from the conventional-
cubic-cell basis to the quantum-well-transport basis whereby effective mass
tensors, valley vectors, strain matrices, anisotropic strain ratios, and
scattering vectors are all defined in their respective bases. The specific
cases of (001)-, (110)-, and (111)-oriented aluminum arsenide (AlAs) quantum
wells are examined, as is the unconventional (411) facet, which is of
particular importance in AlAs literature. Calculations of electron confinement
and strain in the (001), (110), and (411) facets determine the critical well
width for crossover from double- to single-valley degeneracy in each system.
The notation is generalized to include miscut angles, and can be adapted to
other multi-valley systems. To help classify anisotropic inter-valley
scattering events, a new primitive unit cell is defined in momentum space which
allows one to distinguish purely in-plane inter-valley scattering events from
those that requires an out-of-plane momentum scattering component.Comment: 17 pages, 4 figures, 2 table
A Self-learning Nonlinear Variable Gain Proportional Derivative (PD) Controller in Robot Manipulators
This paper proposes a nonlinear variable gain Proportional-Derivative (PD) controller
that exhibits self-constructing and self-learning capabilities. In this method, the
conventional linear PD controller is augmented with a nonlinear variable PD gain control
signal using a dynamic structural network. The dynamic structural network known as
Growing Multi-Experts etwork grows in time by placing hidden nodes in regions of the
state space visited by the system during operation. This results in a network that is
"economic" in terms of network sileo The proposed approach enhances the adaptability
of conventional PD controller while preserving its' linear structure. Based on the
simulation study on variable load and friction compensation, the fast adaptation is shown
to be able to compensate the non-linearity and the uncertainty in the robotic system
Using e-mail recruitment and an online questionnaire to establish effect size: A worked example
Background\ud
Sample size calculations require effect size estimations. Sometimes, effect size estimations and standard deviation may not be readily available, particularly if efficacy is unknown because the intervention is new or developing, or the trial targets a new population. In such cases, one way to estimate the effect size is to gather expert opinion. This paper reports the use of a simple strategy to gather expert opinion to estimate a suitable effect size to use in a sample size calculation.\ud
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Methods\ud
Researchers involved in the design and analysis of clinical trials were identified at the University of Birmingham and via the MRC Hubs for Trials Methodology Research. An email invited them to participate.\ud
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An online questionnaire was developed using the free online tool 'Survey Monkey©'. The questionnaire described an intervention, an electronic participant information sheet (e-PIS), which may increase recruitment rates to a trial. Respondents were asked how much they would need to see recruitment rates increased by, based on 90%. 70%, 50% and 30% baseline rates, (in a hypothetical study) before they would consider using an e-PIS in their research.\ud
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Analyses comprised simple descriptive statistics.\ud
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Results\ud
The invitation to participate was sent to 122 people; 7 responded to say they were not involved in trial design and could not complete the questionnaire, 64 attempted it, 26 failed to complete it. Thirty-eight people completed the questionnaire and were included in the analysis (response rate 33%; 38/115). Of those who completed the questionnaire 44.7% (17/38) were at the academic grade of research fellow 26.3% (10/38) senior research fellow, and 28.9% (11/38) professor. Dependent upon the baseline recruitment rates presented in the questionnaire, participants wanted recruitment rate to increase from 6.9% to 28.9% before they would consider using the intervention.\ud
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Conclusions\ud
This paper has shown that in situations where effect size estimations cannot be collected from previous research, opinions from researchers and trialists can be quickly and easily collected by conducting a simple study using email recruitment and an online questionnaire. The results collected from the survey were successfully used in sample size calculations for a PhD research study protocol.\ud
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