18,771 research outputs found
Ultra-high molecular sink vacuum chamber
Double-wall vacuum chamber can be separated from the remainder of the system and pumped by ultra-clean techniques. Ultrahigh vacuum is maintained by the cryogenic effect of a cold wall and titanium chemisorption
Political corporate social responsibility: reviewing theories and setting new agendas
There has been rising interest in political corporate social responsibility (political CSR), defined as activities where CSR has an intended or unintended political impact, or where intended or unintended political impacts on CSR exist. Based on a survey and content analysis of 146 peer-reviewed academic articles from 18 journals over the 14-year period 2000–2013, this paper systematically reviews the existing applications of general theories (such as legitimacy theory, the resource-based view and Habermasian political theory) within the political CSR literature.The survey indicates that the political CSR field is dominated by institutional theory and stakeholder theory, but future theory development needs to go beyond these theories in order to address a number of critical gaps. This review specifically points to several avenues for future political CSR research with regard to the individual level of analysis, domain integration and political CSR in multinational enterprises. The paper ends with a call for a new theory-informed and pluralist research agenda on political CSR to integrate different perspectives and re-examine the role of the state
Towards dense object tracking in a 2D honeybee hive
From human crowds to cells in tissue, the detection and efficient tracking of
multiple objects in dense configurations is an important and unsolved problem.
In the past, limitations of image analysis have restricted studies of dense
groups to tracking a single or subset of marked individuals, or to
coarse-grained group-level dynamics, all of which yield incomplete information.
Here, we combine convolutional neural networks (CNNs) with the model
environment of a honeybee hive to automatically recognize all individuals in a
dense group from raw image data. We create new, adapted individual labeling and
use the segmentation architecture U-Net with a loss function dependent on both
object identity and orientation. We additionally exploit temporal regularities
of the video recording in a recurrent manner and achieve near human-level
performance while reducing the network size by 94% compared to the original
U-Net architecture. Given our novel application of CNNs, we generate extensive
problem-specific image data in which labeled examples are produced through a
custom interface with Amazon Mechanical Turk. This dataset contains over
375,000 labeled bee instances across 720 video frames at 2 FPS, representing an
extensive resource for the development and testing of tracking methods. We
correctly detect 96% of individuals with a location error of ~7% of a typical
body dimension, and orientation error of 12 degrees, approximating the
variability of human raters. Our results provide an important step towards
efficient image-based dense object tracking by allowing for the accurate
determination of object location and orientation across time-series image data
efficiently within one network architecture.Comment: 15 pages, including supplementary figures. 1 supplemental movie
available as an ancillary fil
From modes to movement in the behavior of C. elegans
Organisms move through the world by changing their shape, and here we explore
the mapping from shape space to movements in the nematode C. elegans as it
crawls on a planar agar surface. We characterize the statistics of the
trajectories through the correlation functions of the orientation angular
velocity, orientation angle and the mean-squared displacement, and we find that
the loss of orientational memory has significant contributions from both
abrupt, large amplitude turning events and the continuous dynamics between
these events. Further, we demonstrate long-time persistence of orientational
memory in the intervals between abrupt turns. Building on recent work
demonstrating that C. elegans movements are restricted to a low-dimensional
shape space, we construct a map from the dynamics in this shape space to the
trajectory of the worm along the agar. We use this connection to illustrate
that changes in the continuous dynamics reveal subtle differences in movement
strategy that occur among mutants defective in two classes of dopamine
receptors
On the nature of the progenitors of three type II-P supernovae: 2004et, 2006my and 2006ov
The pre-explosion observations of the type II-P supernovae 2006my, 2006ov and
2004et, are re-analysed. In the cases of supernovae 2006my and 2006ov we argue
that the published candidate progenitors are not coincident with their
respective supernova sites in pre-explosion Hubble Space Telescope
observations. We therefore derive upper luminosity and mass limits for the
unseen progenitors of both these supernovae, assuming they are red supergiants:
2006my (log L/Lsun = 4.51; mass < 13Msun) and 2006ov (log L/Lsun = 4.29; mass <
10Msun). In the case of supernova 2004et we show that the yellow-supergiant
progenitor candidate, originally identified in Canada France Hawaii Telescope
images, is still visible ~3 years post-explosion in observations from the
William Herschel Telescope. High-resolution Hubble Space Telescope and Gemini
(North) adaptive optics late-time imagery reveal that this source is not a
single yellow supergiant star, but rather is resolved into at least three
distinct sources. We report the discovery of the unresolved progenitor as an
excess of flux in pre-explosion Isaac Newton Telescope i'-band imaging.
Accounting for the late-time contribution of the supernova using published
optical spectra, we calculate the progenitor photometry as the difference
between the pre- and post-explosion, ground-based observations. We find the
progenitor was most likely a late K to late M-type supergiant of 8 +5/-1 Msun.
In all cases we conclude that future, high-resolution observations of the
supernova sites will be required to confirm these results.Comment: 43 pages (pre-print format), 12 figures, 10 tables. Significant
revision following referee's comments. Accepted for publication in MNRA
Ride quality meter
A ride quality meter is disclosed that automatically transforms vibration and noise measurements into a single number index of passenger discomfort. The noise measurements are converted into a noise discomfort value. The vibrations are converted into single axis discomfort values which are then converted into a combined axis discomfort value. The combined axis discomfort value is corrected for time duration and then summed with the noise discomfort value to obtain a total discomfort value
Vibration characteristics of 1/8-scale dynamic models of the space-shuttle solid-rocket boosters
Vibration tests and analyses of six 1/8 scale models of the space shuttle solid rocket boosters are reported. Natural vibration frequencies and mode shapes were obtained for these aluminum shell models having internal solid fuel configurations corresponding to launch, midburn (maximum dynamic pressure), and near endburn (burnout) flight conditions. Test results for longitudinal, torsional, bending, and shell vibration frequencies are compared with analytical predictions derived from thin shell theory and from finite element plate and beam theory. The lowest analytical longitudinal, torsional, bending, and shell vibration frequencies were within + or - 10 percent of experimental values. The effects of damping and asymmetric end skirts on natural vibration frequency were also considered. The analytical frequencies of an idealized full scale space shuttle solid rocket boosted structure are computed with and without internal pressure and are compared with the 1/8 scale model results
- …