1,540 research outputs found
A COMPARISON OF USER PERFORMANCE BETWEEN THE RELATIONAL AND THE EXTENDED ENTITY RELATIONSHIP MODELS IN THE DISCOVERY PHASE OF DATABASE DESIGN
This paper reports on a laboratory study which compared conceptual data models developed by casual autonomous users using the relational and the extended entity relationship (EER) representation techniques. It was found that the EER model led to better user performance in modeling binary relationships, while the relational model was better in modeling unary relationships. Subjects found it difficult to model ternary relationships using either model, although the performance using the EER model was slightly better. In general, there was evidence that the EER model led to better user performance. Subjects using the EER model were more confident about their solutions and perceived the model as easier to use than their relational counterparts. The study\u27s results raise questions concerning user performance using the relational model for a discovery (conceptual modeling) task
The spherical probe electric field and wave experiment
The experiment is designed to measure the electric field and density fluctuations with sampling rates up to 40,000 samples/sec. The description includes Langmuir sweeps that can be made to determine the electron density and temperature, the study of nonlinear processes that result in acceleration of plasma, and the analysis of large scale phenomena where all four spacecraft are needed
Characteristics of Effective GSS Facilitators
As businesses increase their use of groups to solve problems, the importance of strong group facilitation skills has increased. This paper investigates the characteristics of high-performing group facilitators versus low-performing group facilitators. The characteristics investigated represent two broad areas of interest: general facilitator background and skills possessed by the facilitator. The facilitator background factors that proved to be good predictors of high performance included: overall experience and number of computer-supported meeting facilitated. The skills possessed by high performers included: plans and designs meetings, demonstrates flexibility, and listens to, clarifies, and integrates information. The analysis provides a rule for accurately predicting whether a facilitator is a high-performer or a low-performer more than 77% of the time
Beyond Speculative Robot Ethics
In this article we develop a dialogue model for robot technology experts and designated users to discuss visions on the future of robotics in long-term care. Our vision assessment study aims for more distinguished and more informed visions on future robots. Surprisingly, our experiment also lead to some promising co-designed robot concepts in which jointly articulated moral guidelines are embedded. With our model we think to have designed an interesting response on a recent call for a less speculative ethics of technology by encouraging discussions about the quality of positive and negative visions on the future of robotics.
Dalbavancin is thermally stable at clinically relevant temperatures against methicillin-sensitive <i>Staphylococcus Aureus</i>
Introduction: While the rate of orthopaedic infections has remained constant
over the years, the burden on healthcare systems continues to rise with an
aging population. Local antibiotic delivery via polymethyl methacrylate bone
cement is a common adjunct in treating bone and joint infections.
Dalbavancin is a novel lipoglycopeptide antibiotic in the same class as
vancomycin that has shown efficacy against Gram-positive organisms when used
systemically but has not been investigated as a local antibiotic. This study
aims to identify whether dalbavancin is thermally stable at the temperatures
expected during the polymerization of polymethyl methacrylate cement.
Methods: Stock solutions of dalbavancin were prepared and heated using a
polymerase chain reaction machine based upon previously defined models of
curing temperatures in two clinically relevant models: a 10 mm
polymethyl methacrylate bead and a polymethyl methacrylate articulating knee
spacer model. Aliquots of heated dalbavancin were then transferred to be
incubated at core body temperature (37 ∘C) and analyzed at various
time points up to 28 d. The minimum inhibitory concentration at which
90 % of colonies were inhibited (MIC90) for each heated sample was
determined against methicillin-sensitive Staphylococcus aureus (American Type Culture Collection, ATCC, 0173K) using a standard
microbroth dilution assay.
Results: The average MIC90 of dalbavancin was 1.63 µg mL−1
±0.49 against 0173K S. aureus. There were no significant differences in the
relative MIC90 values after heating dalbavancin in either model
compared to unheated control dalbavancin.
Conclusions: Dalbavancin is thermally stable at the curing temperatures of
polymethyl methacrylate cement and at human core body temperature over
28 d. Future in vitro and in vivo studies are warranted to further investigate the role
of dalbavancin as a local antibiotic prior to its clinical use.</p
Developing post-alert messaging for ShakeAlert, the earthquake early warning system for the west coast of the United States of America
As ShakeAlert, the earthquake early warning system for the West Coast of the U.S., begins its transition to operational public alerting, we explore how post-alert messaging might represent system performance. Planned post-alert messaging can provide timely, crucial information to both emergency managers and ShakeAlert operators as well as calibrate expectations among various publics or public user groups and inform their responses to future alerts. There is a concern among the scientists and emergency managers that false alerts may negatively impact trust in the system, so quickly disseminated post-alert messages are necessary. For a new early warning system, such as ShakeAlert, this is particularly relevant given that the potentially affected population is likely to be unfamiliar with this system. We address this concern in six steps: (1) assessment of ShakeAlert performance to date, (2) characterization of human behavior and response to earthquake alerts, (3) presentation of a decision tree for issuing post-alert messages, (4) design of a critical set of post-alert messaging scenarios, (5) elaboration of these scenarios with message templates for a variety of communication channels and (6) development of a typology of earthquake alerts. We further explore methods for monitoring and evaluating ShakeAlert post-alert messaging, for continuous improvement to the system
Developing post-alert messaging for ShakeAlert, the earthquake early warning system for the west coast of the United States of America
As ShakeAlert, the earthquake early warning system for the West Coast of the U.S., begins its transition to operational public alerting, we explore how post-alert messaging might represent system performance. Planned post-alert messaging can provide timely, crucial information to both emergency managers and ShakeAlert operators as well as calibrate expectations among various publics or public user groups and inform their responses to future alerts. There is a concern among the scientists and emergency managers that false alerts may negatively impact trust in the system, so quickly disseminated post-alert messages are necessary. For a new early warning system, such as ShakeAlert, this is particularly relevant given that the potentially affected population is likely to be unfamiliar with this system. We address this concern in six steps: (1) assessment of ShakeAlert performance to date, (2) characterization of human behavior and response to earthquake alerts, (3) presentation of a decision tree for issuing post-alert messages, (4) design of a critical set of post-alert messaging scenarios, (5) elaboration of these scenarios with message templates for a variety of communication channels and (6) development of a typology of earthquake alerts. We further explore methods for monitoring and evaluating ShakeAlert post-alert messaging, for continuous improvement to the system
The Mathematical Universe
I explore physics implications of the External Reality Hypothesis (ERH) that
there exists an external physical reality completely independent of us humans.
I argue that with a sufficiently broad definition of mathematics, it implies
the Mathematical Universe Hypothesis (MUH) that our physical world is an
abstract mathematical structure. I discuss various implications of the ERH and
MUH, ranging from standard physics topics like symmetries, irreducible
representations, units, free parameters, randomness and initial conditions to
broader issues like consciousness, parallel universes and Godel incompleteness.
I hypothesize that only computable and decidable (in Godel's sense) structures
exist, which alleviates the cosmological measure problem and help explain why
our physical laws appear so simple. I also comment on the intimate relation
between mathematical structures, computations, simulations and physical
systems.Comment: Replaced to match accepted Found. Phys. version, 31 pages, 5 figs;
more details at http://space.mit.edu/home/tegmark/toe.htm
The universe formation by a space reduction cascade with random initial parameters
In this paper we discuss the creation of our universe using the idea of extra
dimensions. The initial, multidimensional Lagrangian contains only metric
tensor. We have found many sets of the numerical values of the Lagrangian
parameters corresponding to the observed low-energy physics of our universe.
Different initial parameters can lead to the same values of fundamental
constants by the appropriate choice of a dimensional reduction cascade. This
result diminishes the significance of the search for the 'unique' initial
Lagrangian. We also have obtained a large number of low-energy vacua, which is
known as a 'landscape' in the string theory.Comment: 17 pages, 1 figur
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