2,034 research outputs found
Innovation and Business Strategy: Why Canada Falls Short
This article compares the development of labour productivity in the Swedish and the Finnish business sectors and the role of the information and communication technology (ICT) sector in this process. The results show that the Finnish productivity level has been converging towards the Swedish level, but that there is still a significant difference. This trend has coincided with the growing importance of the ICT sector, especially since the mid 1990s. Due to higher productivity and employment growth, the Finnish ICT sector has contributed to this convergence. This is explained by the electrical engineering industry. The Nokia effect has been stronger than the Ericsson effect.Innovation, productivity, business strategy, public policy, market structure, Competition, business climate, business ambition
Peer Effects in Medical School
Using data on the universe of students who graduated from U.S. medical schools between 1996 and 1998, we examine whether the abilities and specialty preferences of a medical school class affect a student's academic achievement in medical school and his choice of specialty. We mitigate the selection problem by including school-specific fixed effects, and show that this method yields an upper bound on peer effects for our data. We estimate positive peer effects that disappear when school-specific fixed effects are added to control for the endogeneity of a peer group. We find no evidence that peer effects are stronger for blacks, that peer groups are formed along racial lines, or that students with relatively low ability benefit more from their peers than students with relatively high ability. However, we do find some evidence that peer groups form along gender lines.
An ex vivo comparison of the tensile strengthening properties of protein derivatives on damaged hair
Conventional conditioning agents, cationic surfactants and polymers, are often limited in their ability to repair and strengthen the hair fibre, while protein-derived actives have been found to enhance the tensile strength of damaged hair. This study investigates the effects of keratin, wheat and collagen hydrolysates on the tensile strength of three types of damaged hair: bleached, permed and thermally treated
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Application of the conditioned network concept in high frequency power line carrier
The aim of the research described in this thesis was to investigate the possible use of underground Low Voltage Distribution Networks as a medium for the propagation of high frequency communication and data signals. Although the results and observations presented are based upon work carried out on a typical UK urban underground network, the same principles apply to most European underground Low Voltage Distribution Networks. The work was based around the use of frequencies greater than 1 MHz; these high frequencies provide enough bandwidth for a number of value added services to be offered in addition to the more usual Utility requirements for remote meter reading and load control. The research resulted in the development of an in-line filter element designed to limit the amount of Power Line Carrier noise egress from a distribution network whilst at the same time reducing the amount of high frequency noise entering the network. The effects of the Electricity Distribution Network on high frequency signals are discussed in some detail. All Power Line Carrier systems must be capable of operating in the presence of noise. Network topology and individual network elements have a significant effect on high frequency signals; a number of topologies are described and the effects of changes in characteristic impedance and discontinuities are discussed. The results and observations were largely obtained from a Low Voltage Electricity Distribution Network in Kendal, Cumbria. The limited availability of expensive high frequency test equipment resulted in the need to develop unique testing procedures; these are described in full. Sample results from the tests undertaken in Kendal are presented and discussed. The Conditioned Network concept is outlined and the design rules used to develop the in-line Conditioning Unit highlighted. A mathematical model for the filter element of the Conditioning Unit is developed and compared to empirical results obtained from laboratory experiments
Automation of garment assembly processes
Robotic automation in apparel manufacturing is reviewed and investigated. Gripper design for separation and de-stacking of batch cut fabric components is identified as an important factor in implementing such automation and a study of existing gripper mechanisms is presented. New de-stacking gripper designs and processes are described together with experimental results. Single fabric component handling, alignment and registration techniques are investigated. Some of these techniques are integrated within a demonstrator robotic garment assembly cell automating the common edge binding process. Performance results are reported
Tidal friction in early-type stars
The tidal torque on an early-type star is concentrated near the boundary between the convective core and radiative envelope and a train of gravity waves is excited there. The angular momentum which the torque removes from the fluid is transported outward by the gravity waves, which carry negative angular momentum. Before the surface layers are despun to synchronous rotation, the gravity waves propagate to just below the photosphere where they suffer radiative damping and are partially reflected. It is here that the negative angular momentum is deposited and the primary tidal despinning takes place. The surface layers cannot be
spun down below synchronous rotation because as a train of gravity waves approaches a corotation resonance its group velocity and wavelength tend to zero, its amplitude diverges, and it is completely absorbed. Thus, tidal despinning to synchronous rotation proceeds from the outside toward the inside of the star. Our picture provides a neat explanation for the otherwise puzzling discovery by Giuricin, Mardirossian, and Mezzetti that Zahn's theory for tidal evolution in early-type close binaries seems to be compatible with the observed rates of orbit circularization while significantly underestimating the observed rates of spin synchronization
Tides in rotating fluids
We consider the tidal disturbance forced in a differentially rotating fluid by a rigidly rotating external
potential. The fluid is assumed to be inviscid, insulated, and self-gravitating, and to have laminar unperturbed
and perturbed velocity fields. The external potential may exert a steady torque on the fluid which is of second
order in Its strength. However, to this order, we prove that there are no secular changes in the angular momenta of fluid particles, except possibly at corotation where the angular velocity, Ω(r,θ), is equal to the pattern speed of the potential, Ω_p. A corollary of our theorem is that, except at corotation, all of the angular momentum transferred to the fluid by the external potential must be transported away by internal stresses. In the applications of which we are aware, these stresses are associated with waves
Peer Effects, Learning, and Physician Specialty Choice
Sixty percent of medical students switch specialties between the first and fourth year of medical school. These changes have a profound impact on the students' future earnings because there are substantial income differences between specialties. In 1997, for example, the mean income ranged from 133,000 in psychiatry. In this paper we use a unique data set that contains the universe of students who graduated from a U.S. medical school between 1996 and 1998 to examine factors that influence specialty choices. There are possible several reasons why so many students switch specialties. One possibility is that switching occurs because residency positions in high-income specialties such as orthopedic surgery and dermatology are rationed, based in part on a student's performance during medical school. As students learn about their own performance during medical school and learn about the rationing rule -- students who perform well in medical school have a higher probability of entering competitive, high-income specialties -- they adjust their specialty choice accordingly. Another possibility is that the ability and specialty preferences of a student's peer group affects his own performance and specialty choice. Finally, schools might exert their own influence on a student s performance and specialty choice. Empirical Model We divide the specialty decision into two parts. A student arrives at medical school aware of his ability, as measured by the Medical College Admission Test (MCAT) score, and his preferred specialty. Medical students take the Step 1 National Board of Medical Examiners test after their second year of school. In the first part of the model, first-year medical students forecast their performance on the board exam based on their ability, the average ability of their medical school classmates (the ability peer effect), their current preferred specialty, and the school they attend. The first-year specialty preference is included to account for the possibility that students with similar levels of unobserved ability will select the same specialty, and students who plan to enter competitive specialties might work harder in order to increase the likelihood of entering the specialty. The error term from the regression of the board score on the forecasting variables is interpreted as a `performance shock' -- new information a student receives regarding his or her performance in school. In the second part of the model, the probability that a fourth-year student chooses a high-paying specialty is assumed to be a function of their predicted performance on the board exam, the performance shock, their first-year specialty preference, the first-year specialty preferences of their classmates (the specialty preference peer effect), and the school they attend. Data The sample consists of 37,000 medical students who graduated from one of the 127 U.S. medical schools in 1996, 1997, or 1998. We have information on students' ability prior to medical school, their performance during medical school, and their specialty preferences at the beginning and end of medical school. A student's pre-matriculation ability is represented by their test score on the biology, chemistry, and reading components of the MCAT, a uniform exam given to all medical school applicants. The Step 1 board score, also a uniform national exam, measures a student's performance in medical school. Students are surveyed by the Association of American Medical Colleges in their first and fourth years of medical school and asked to indicate their preferred specialty. Because we have the universe of U.S. medical students, we can measure ability and preference peer effects: the average pre-matriculation ability of each school's students and the proportion of each school's first-year students who prefer each specialty. Results Among first-year students, there are no substantial differences in MCAT scores between specialties. By the fourth year, however, students with high board scores are more likely to be in high-income specialties. Students who receive a positive performance shock -- a higher board score than they expected -- are much more likely to switch to a high-income specialty relative to other students. Women are more likely than men to choose a low-income specialty in the fourth year, conditional on their board score and initial specialty preference. Peer effects are an important determinant of board scores and specialty choices, but these effects disappear when we include school-specific fixed effects.
High Angular Resolution Stellar Imaging with Occultations from the Cassini Spacecraft II: Kronocyclic Tomography
We present an advance in the use of Cassini observations of stellar
occultations by the rings of Saturn for stellar studies. Stewart et al. (2013)
demonstrated the potential use of such observations for measuring stellar
angular diameters. Here, we use these same observations, and tomographic
imaging reconstruction techniques, to produce two dimensional images of complex
stellar systems. We detail the determination of the basic observational
reference frame. A technique for recovering model-independent brightness
profiles for data from each occulting edge is discussed, along with the
tomographic combination of these profiles to build an image of the source star.
Finally we demonstrate the technique with recovered images of the {\alpha}
Centauri binary system and the circumstellar environment of the evolved
late-type giant star, Mira.Comment: 8 pages, 8 figures, Accepted by MNRA
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