6,657 research outputs found
A Survey Of Knowledge Management Skills Acquisition In An Online Team-Based Distributed Computing Course
This paper investigates students’ perceptions of their acquisition of knowledge management skills, namely thinking and team-building skills, resulting from the integration of various resources and technologies into an entirely team-based, online upper level distributed computing (DC) information systems (IS) course. Results seem to indicate that more support of the thinking skills was provided by the offline resources than by the online resources, while both the online and offline resources were perceived as providing a lot of support for the team-building skills
Modeling Creativity For The Multinational Firm
Much has been written about the proliferation of the modern multinational corporation (MNC) as a primary driver of globalization [Bhagwati, 2004; Rugman and Verbeke 2004; Wolf. 2004]. A common theme shared by all MNCs expanding into foreign markets is the notion of how best to manage the knowledge assets of the firm from all perspectives in order to achieve maximum performance while concomitantly increasing the ability of the firm to innovate while expanding. This paper examines the processes of idea creation within multinational corporations in parallel with the role that information and communication technology (ICT) plays as a driver of that innovation
Comparison of Routable Control System Security Approaches
This document is an supplement to the 'Secure and Efficient Routable Control Systems.' It addressed security in routable control system communication. The control system environment that monitors and manages the power grid historically has utilized serial communication mechanisms. Leased-line serial communication environments operating at 1200 to 9600 baud rates are common. However, recent trends show that communication media such as fiber, optical carrier 3 (OC-3) speeds, mesh-based high-speed wireless, and the Internet are becoming the media of choice. In addition, a dichotomy has developed between the electrical transmission and distribution environments, with more modern communication infrastructures deployed by transmission utilities. The preceding diagram represents a typical control system. The Communication Links cloud supports all of the communication mechanisms a utility might deploy between the control center and devices in the field. Current methodologies used for security implementations are primarily led by single vendors or standards bodies. However, these entities tend to focus on individual protocols. The result is an environment that contains a mixture of security solutions that may only address some communication protocols at an increasing operational burden for the utility. A single approach is needed that meets operational requirements, is simple to operate, and provides the necessary level of security for all control system communication. The solution should be application independent (e.g., Distributed Network Protocol/Internet Protocol [DNP/IP], International Electrotechnical Commission [IEC] C37.118, Object Linking and Embedding for Process Control [OPC], etc.) and focus on the transport layer. In an ideal setting, a well-designed suite of standards for control system communication will be used for vendor implementation and compliance testing. An expected outcome of this effort is an international standard
The MASSIVE Survey - X. Misalignment between Kinematic and Photometric Axes and Intrinsic Shapes of Massive Early-Type Galaxies
We use spatially resolved two-dimensional stellar velocity maps over a
field of view to investigate the kinematic features of 90
early-type galaxies above stellar mass in the MASSIVE
survey. We measure the misalignment angle between the kinematic and
photometric axes and identify local features such as velocity twists and
kinematically distinct components. We find 46% of the sample to be well aligned
(), 33% misaligned, and 21% without detectable rotation
(non-rotators). Only 24% of the sample are fast rotators, the majority of which
(91%) are aligned, whereas 57% of the slow rotators are misaligned with a
nearly flat distribution of from to . 11
galaxies have and thus exhibit minor-axis ("prolate")
rotation in which the rotation is preferentially around the photometric major
axis. Kinematic misalignments occur more frequently for lower galaxy spin or
denser galaxy environments. Using the observed misalignment and ellipticity
distributions, we infer the intrinsic shape distribution of our sample and find
that MASSIVE slow rotators are consistent with being mildly triaxial, with mean
axis ratios of and . In terms of local kinematic features,
51% of the sample exhibit kinematic twists of larger than , and 2
galaxies have kinematically distinct components. The frequency of misalignment
and the broad distribution of reported here suggest that the most
massive early-type galaxies are mildly triaxial, and that formation processes
resulting in kinematically misaligned slow rotators such as gas-poor mergers
occur frequently in this mass range.Comment: Accepted to MNRA
The Colors of Dwarf Elliptical Galaxy Globular Cluster Systems, Nuclei and Stellar Halos
We present the results of a Hubble Space Telescope WFPC2 F555W and F814W
survey of 69 dwarf elliptical galaxies (dEs) in the Virgo and Fornax Clusters
and Leo Group. The colors of the dE globular clusters, nuclei, and
underlying field star populations are used to trace the dE star-formation
histories. We find that the dE globular cluster candidates are as blue as the
metal-poor globular clusters of the Milky Way. The observed correlation of the
dE globular cluster systems' color with the luminosity of the host dE is
strong evidence that the globular clusters were formed within the the halos of
dEs and do not have a pre-galactic origin. Assuming the majority of dE clusters
are old, the mean globular cluster color- host galaxy luminosity correlation
implies a cluster metallicity galaxy luminosity relation of , which is significantly shallower than the field star
metallicity - host galaxy luminosity relationship observed in Local Group
dwarfs (). The dE stellar envelopes are
magnitudes redder in than their globular clusters and nuclei. This color
offset implies separate star-formation episodes within the dEs for the clusters
and field stars, while the very blue colors of two dE nuclei trace a third
star-formation event in those dEs less than a Gyr ago.Comment: 39 pages, including 5 tables and 10 figures; accepted by the
Astrophysical Journa
A Detailed Observational Analysis of V1324 Sco, the Most Gamma-Ray Luminous Classical Nova to Date
It has recently been discovered that some, if not all, classical novae emit
GeV gamma rays during outburst, but the mechanisms involved in the production
of the gamma rays are still not well understood. We present here a
comprehensive multi-wavelength dataset---from radio to X-rays---for the most
gamma-ray luminous classical nova to-date, V1324 Sco. Using this dataset, we
show that V1324 Sco is a canonical dusty Fe-II type nova, with a maximum ejecta
velocity of 2600 km s and an ejecta mass of few
M. There is also evidence for complex shock interactions, including a
double-peaked radio light curve which shows high brightness temperatures at
early times. To explore why V1324~Sco was so gamma-ray luminous, we present a
model of the nova ejecta featuring strong internal shocks, and find that higher
gamma-ray luminosities result from higher ejecta velocities and/or mass-loss
rates. Comparison of V1324~Sco with other gamma-ray detected novae does not
show clear signatures of either, and we conclude that a larger sample of
similarly well-observed novae is needed to understand the origin and variation
of gamma rays in novae.Comment: 26 pages, 13 figure
Distribution of postsynaptic density (PSD)-95 and Ca2+/calmodulin-dependent protein kinase II at the PSD
Author Posting. © Society for Neuroscience, 2003. This article is posted here by permission of Society for Neuroscience for personal use, not for redistribution. The definitive version was published in Journal of Neuroscience 23 (2003): 11270-11278.Postsynaptic densities (PSDs) contain proteins that regulate synaptic transmission. We determined the positions of calcium/calmodulin-dependent protein kinase II (CaMKII) and PSD-95 within the three-dimensional structure of isolated PSDs using immunogold labeling, rotary shadowing, and electron microscopic tomography. The results show that all PSDs contain a central mesh immediately underlying the postsynaptic membrane. Label for PSD-95 is found on both the cytoplasmic and cleft sides of this mesh, averaging 12 nm from the cleft side. All PSDs label for PSD-95. The properties of CaMKII labeling are quite different. Label is virtually absent on the cleft sides of PSDs, but can be heavy on the cytoplasmic side at a mean distance of 25 nm from the cleft. In tomograms, CaMKII holoenzymes can be visualized directly, appearing as labeled, tower-like structures reflecting the 20 nm diameter of the holoenzyme. These towers protrude from the cytoplasmic side of the central mesh. There appears to be a local organization of CaMKII, as judged by fact that the nearest-neighbor distances are nearly invariant over a wide range of labeling density for CaMKII. The average density of CaMKII holoenzymes is highly variable, ranging from zero to values approaching a tightly packed state. This variability is significantly higher than that for PSD-95 and is consistent with an information storage role for CaMKII.This work was supported by National Institute of Neurological Disorders and Stroke Grants RO1 NS-27337 and
RO1 NS-35083 (J.L.)
SN 2017ein and the Possible First Identification of a Type Ic Supernova Progenitor
We have identified a progenitor candidate in archival Hubble Space Telescope
(HST) images for the Type Ic SN 2017ein in NGC 3938, pinpointing the
candidate's location via HST Target-of-Opportunity imaging of the SN itself.
This would be the first identification of a stellar-like object as a progenitor
candidate for any Type Ic supernova to date. We also present observations of SN
2017ein during the first ~49 days since explosion. We find that SN 2017ein most
resembles the well-studied Type Ic SN 2007gr. We infer that SN 2017ein
experienced a total visual extinction of A_V~1.0--1.9 mag, predominantly
because of dust within the host galaxy. Although the distance is not well
known, if this object is the progenitor, it was likely of high initial mass,
~47--48 M_sun if a single star, or ~60--80 M_sun if in a binary system.
However, we also find that the progenitor candidate could be a very blue and
young compact cluster, further implying a very massive (>65 M_sun) progenitor.
Furthermore, the actual progenitor might not be associated with the candidate
at all and could be far less massive. From the immediate stellar environment,
we find possible evidence for three different populations; if the SN progenitor
was a member of the youngest population, this would be consistent with an
initial mass of ~57 M_sun. After it has faded, the SN should be reobserved at
high spatial resolution and sensitivity, to determine whether the candidate is
indeed the progenitor.Comment: Revised, following referee's comments, and accepted to ApJ; 21 pages,
10 figure
The Difficulty of Teaching Adults to Recognize Referential Ambiguity in Children’s Testimony: The Influence of Explicit Instruction and Sample Questions
Adults often fail to recognize the ambiguity of children's unelaborated responses to “Do you know/remember (DYK/R) if/whether” questions. Two studies examined whether sample questions and/or an explicit instruction would improve adults' ability to recognize referential ambiguity in children's testimony. In Study 1 (N = 383), participants rarely recognized referential ambiguity in the sample questions or in children's testimony, and answering sample questions had no influence on their ability to detect ambiguity in children's testimony. Study 2 (N = 363) attempted to clarify the meaning of ambiguity for participants with explicit instructions. Results revealed that although an explicit instruction improved performance on sample questions, this also led to an overcorrection, and instructions and sample questions only modestly improved adults' ability to recognize referential ambiguity in children's testimony. Ultimately, the absence of an effective strategy for alerting adults to the problem of referential ambiguity highlights the dangers of DYK/R if/whether questions
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