1,585 research outputs found
Probabilistic Perspectives on Collecting Human Uncertainty in Predictive Data Mining
In many areas of data mining, data is collected from humans beings. In this
contribution, we ask the question of how people actually respond to ordinal
scales. The main problem observed is that users tend to be volatile in their
choices, i.e. complex cognitions do not always lead to the same decisions, but
to distributions of possible decision outputs. This human uncertainty may
sometimes have quite an impact on common data mining approaches and thus, the
question of effective modelling this so called human uncertainty emerges
naturally.
Our contribution introduces two different approaches for modelling the human
uncertainty of user responses. In doing so, we develop techniques in order to
measure this uncertainty at the level of user inputs as well as the level of
user cognition. With support of comprehensive user experiments and large-scale
simulations, we systematically compare both methodologies along with their
implications for personalisation approaches. Our findings demonstrate that
significant amounts of users do submit something completely different (action)
than they really have in mind (cognition). Moreover, we demonstrate that
statistically sound evidence with respect to algorithm assessment becomes quite
hard to realise, especially when explicit rankings shall be built
Casimir force between sharp-shaped conductors
Casimir forces between conductors at the sub-micron scale cannot be ignored
in the design and operation of micro-electromechanical (MEM) devices. However,
these forces depend non-trivially on geometry, and existing formulae and
approximations cannot deal with realistic micro-machinery components with sharp
edges and tips. Here, we employ a novel approach to electromagnetic scattering,
appropriate to perfect conductors with sharp edges and tips, specifically to
wedges and cones. The interaction of these objects with a metal plate (and
among themselves) is then computed systematically by a multiple-scattering
series. For the wedge, we obtain analytical expressions for the interaction
with a plate, as functions of opening angle and tilt, which should provide a
particularly useful tool for the design of MEMs. Our result for the Casimir
interactions between conducting cones and plates applies directly to the force
on the tip of a scanning tunneling probe; the unexpectedly large temperature
dependence of the force in these configurations should attract immediate
experimental interest
Simulation of Low-density Nozzle Plumes in Non-zero Ambient Pressures
The direct simulation Monte-Carlo (DSMC) method was applied to the analysis of low-density nitrogen plumes exhausting from a small converging-diverging nozzle into finite ambient pressures. Two cases were considered that simulated actual test conditions in a vacuum facility. The numerical simulations readily captured the complicated flow structure of the overexpanded plumes adjusting to the finite ambient pressures, including Mach disks and barrel shaped shocks. The numerical simulations compared well to experimental data of Rothe
Antarctic Mapping Mission Planning Aids
On November 4, 1995, the Canadian RADARSAT was carried aloft by a NASA rocket launched from Vandenburg Air Force Base. Radarsat is equipped with a C-band Synthetic Aperture Radar (SAR) capable of acquiring high resolution (25 m) images of Earth's surface day or night and under all weather conditions. Along with the attributes familiar to researchers working with SAR data from the European Space Agency's Earth Remote Sensing Satellite and the Japanese Earth Resources Satellite, RADARSAT will have enhanced flexibility to collect data using a variety of swath widths, incidence angles and resolutions. Most importantly, for scientists interested in Antarctica, the agreement for a U.S. launch of RADARSAT includes a provision for rotating in orbit the normally right-looking SAR to a left-looking mode. This 'Antarctic Mode' will provide for the first time a nearly instantaneous, high resolution view of the entirety of Antarctica on each of two proposed mappings separated by 2 years. This is an unprecedented opportunity to finish mapping one of the few remaining uncharted regions of the Earth. The completed maps will also provide two important benchmarks for gauging changes of Antarctica's ice cover. The preparation of a digital mosaic of Antarctica is being conducted under a NASA Pathfinder Project awarded to the Byrd Polar Research Center of The Ohio State University. The primary goal of this proposal is to compile digital SAR mosaics of the entire Antarctic continent using a combination of standard and extended beams during the "Antarctic Mode" of the Radarsat Mission. Agreements with the Canadian Space Agency call for the first Antarctic Mapping Manuever to occur in September, 1997. A mission plan to coordinate that complex acquisition and downlinking of Antarctic data has been developed by NASA's Jet Propulsion Laboratory. The Alaska SAR Facility (ASF) will be used as the primary data collection site supported by collections at the Canadian Gatineau and Prince Albert Ground Stations. ASF will process data into images which will be sent to OSU for compositing into map products using state-of-the-art equipment to be designed by Vexcel Corporation of Boulder Colorado. Imaging geometry will be constrained over the Antarctic using active radar transponders constructed by the Environmental Research Institute of Michigan and by corner reflectors deployed by the British Antarctic Survey. Additional ground control is being supplied by the National Imagery and Mapping Agency. Final products will be distributed through the ASF and the National Snow and Ice Data Center which are both NASA Data Archive Centers. The mosaics and ancillary information will be prepared on CDROM and will be made available to the science community through NASA DAACs. Science opportunities envisioned for the program are summarized on the accompanying table. These include studying the dynamics and variability of the Antarctic Ice Sheet including studies of regions like the Wordie Ice Shelf and the Larsen Ice Shelf which have recently experienced unexplained and nearly catastropic retreat. Geologic applications include large scale mapping of faults, volcanic features, and mountain building processes (particularly the Transantarctic Mountains). Finally, there is simply the unprecedented opportunity to use these digital maps in studies of many previously unexplored areas of the Southern Continent.NASACanadian Space Agenc
H0LiCOW XII. Lens mass model of WFI2033-4723 and blind measurement of its time-delay distance and
We present the lens mass model of the quadruply-imaged gravitationally lensed
quasar WFI2033-4723, and perform a blind cosmographical analysis based on this
system. Our analysis combines (1) time-delay measurements from 14 years of data
obtained by the COSmological MOnitoring of GRAvItational Lenses (COSMOGRAIL)
collaboration, (2) high-resolution imaging,
(3) a measurement of the velocity dispersion of the lens galaxy based on
ESO-MUSE data, and (4) multi-band, wide-field imaging and spectroscopy
characterizing the lens environment. We account for all known sources of
systematics, including the influence of nearby perturbers and complex
line-of-sight structure, as well as the parametrization of the light and mass
profiles of the lensing galaxy. After unblinding, we determine the effective
time-delay distance to be , an average
precision of . This translates to a Hubble constant , assuming a flat CDM
cosmology with a uniform prior on in the range [0.05, 0.5].
This work is part of the Lenses in COSMOGRAIL's Wellspring (H0LiCOW)
collaboration, and the full time-delay cosmography results from a total of six
strongly lensed systems are presented in a companion paper (H0LiCOW XIII).Comment: Version accepted by MNRAS. 29 pages including appendix, 17 figures, 6
tables. arXiv admin note: text overlap with arXiv:1607.0140
Repulsive Casimir forces
We discuss repulsive Casimir forces between dielectric materials with non
trivial magnetic susceptibility. It is shown that considerations based on naive
pair-wise summation of Van der Waals and Casimir Polder forces may not only
give an incorrect estimate of the magnitude of the total Casimir force, but
even the wrong sign of the force when materials with high dielectric and
magnetic response are involved. Indeed repulsive Casimir forces may be found in
a large range of parameters, and we suggest that the effect may be realized in
known materials. The phenomenon of repulsive Casimir forces may be of
importance both for experimental study and for nanomachinery applications
Intraoperative fracture of phacoemulsification sleeve
<p>Abstract</p> <p>Background</p> <p>We describe a case of intraoperative fracture of phacoemulsification sleeve during phacoemulsification surgery.</p> <p>Case presentation</p> <p>Phacoemulsification surgery was performed in the left eye of a 58-year-old lady with grade II nuclear sclerosis & grade I cortical cataract. Towards the end of quadrant removal, there was anterior chamber instability with impaired followability of nuclear fragments. The distal part of the fractured sleeve remained inside the anterior chamber upon removal of the phacoemulsification probe. The retained sleeve was retrieved with a pair of forceps through the corneal incision site, which did not require widening. There was no missing fragments retained intraocularly and the patient had an uneventful recovery with vision of 20/25 at three months post-operatively.</p> <p>Conclusion</p> <p>Phacoemulsification sleeve fracture is an uncommon complication. With early identification of this condition and proper management, major complications can be avoided.</p
Repeat intracoronary radiation for in-stent restenosis in patients who failed radiation therapy: re-WRIST
Bistability in Apoptosis by Receptor Clustering
Apoptosis is a highly regulated cell death mechanism involved in many
physiological processes. A key component of extrinsically activated apoptosis
is the death receptor Fas, which, on binding to its cognate ligand FasL,
oligomerize to form the death-inducing signaling complex. Motivated by recent
experimental data, we propose a mathematical model of death ligand-receptor
dynamics where FasL acts as a clustering agent for Fas, which form locally
stable signaling platforms through proximity-induced receptor interactions.
Significantly, the model exhibits hysteresis, providing an upstream mechanism
for bistability and robustness. At low receptor concentrations, the bistability
is contingent on the trimerism of FasL. Moreover, irreversible bistability,
representing a committed cell death decision, emerges at high concentrations,
which may be achieved through receptor pre-association or localization onto
membrane lipid rafts. Thus, our model provides a novel theory for these
observed biological phenomena within the unified context of bistability.
Importantly, as Fas interactions initiate the extrinsic apoptotic pathway, our
model also suggests a mechanism by which cells may function as bistable
life/death switches independently of any such dynamics in their downstream
components. Our results highlight the role of death receptors in deciding cell
fate and add to the signal processing capabilities attributed to receptor
clustering.Comment: Accepted by PLoS Comput Bio
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