151 research outputs found
Nonholonomic Feedback Control Among Moving Obstacles
A feedback controller is developed for navigating a nonholonomic vehicle in an area with multiple stationary and possibly moving obstacles. Among other applications the developed algorithms can be used for automatic parking of a passenger car in a parking lot with complex configuration or a ground robot in cluttered environment. Several approaches are explored which combine nonholonomic systems control based on sliding modes and potential field methods
Recommended from our members
Physician Accuracy in Interpreting Potential STâSegment Elevation Myocardial Infarction Electrocardiograms
Background: With adoption of telemedicine, physicians are increasingly asked to diagnose STâsegment elevation myocardial infarctions (STEMIs) based on electrocardiograms (ECGs) with minimal associated clinical information. We sought to determine physicians' diagnostic agreement and accuracy when interpreting potential STEMI ECGs. Methods and Results: A crossâsectional survey was performed consisting of 36 deidentified ECGs that had previously resulted in putative STEMI diagnoses. Emergency physicians, cardiologists, and interventional cardiologists participated in the survey. For each ECG, physicians were asked, âbased on the ECG above, is there a blocked coronary artery present causing a STEMI?â The reference standard for ascertaining the STEMI diagnosis was subsequent emergent coronary arteriography. Responses were analyzed with generalized estimating equations to account for nested and repeated measures. One hundred twentyâfour physicians interpreted a total of 4392 ECGs. Among all physicians, interreader agreement (kappa) for ECG interpretation was 0.33, reflecting poor agreement. The sensitivity to identify âtrueâ STEMIs was 65% (95% CI: 63 to 67) and the specificity was 79% (95% CI: 77 to 81). There was a 6% increase in the odds of accurate ECG interpretation for every 5 years of experience since medical school graduation (OR 1.06, 95% CI: 1.02 to 1.10, P=0.01). After adjusting for experience, there was no significant difference in the odds of accurate interpretation by specialtyâEmergency Medicine (reference), General Cardiology (AOR 0.97, 95% CI: 0.79 to 1.2, P=0.80), or Interventional Cardiology physicians (AOR 1.24, 95% CI: 0.93 to 1.7, P=0.15). Conclusions: There is significant physician disagreement in interpreting ECGs with features concerning for STEMI. Such ECGs lack the necessary sensitivity and specificity to act as a suitable âstandâaloneâ diagnostic test
Report on the International Colloquium on Cardio-Oncology (Rome, 12â14 March 2014)
Cardio-oncology is a relatively new discipline that focuses on the cardiovascular sequelae of anti-tumour drugs. As any other young adolescent discipline, cardio-oncology struggles to define its scientific boundaries and to identify best standards of care for cancer patients or survivors at risk of cardiovascular events. The International Colloquium on Cardio-Oncology was held in Rome, Italy, 12â14 March 2014, with the aim of illuminating controversial issues and unmet needs in modern cardio-oncology. This colloquium embraced contributions from different kind of disciplines (oncology and cardiology but also paediatrics, geriatrics, genetics, and translational research); in fact, cardio-oncology goes way beyond the merging of cardiology with oncology. Moreover, the colloquium programme did not review cardiovascular toxicity from one drug or the other, rather it looked at patients as we see them in their fight against cancer and eventually returning to everyday life. This represents the melting pot in which anti-cancer therapies, genetic backgrounds, and risk factors conspire in producing cardiovascular sequelae, and this calls for screening programmes and well-designed platforms of collaboration between one key professional figure and another. The International Colloquium on Cardio-Oncology was promoted by the Menarini International Foundation and co-chaired by Giorgio Minotti (Rome), Joseph R Carver (Philadelphia, Pennsylvania, United States), and Steven E Lipshultz (Detroit, Michigan, United States). The programme was split into five sessions of broad investigational and clinical relevance (what is cardiotoxicity?, cardiotoxicity in children, adolescents, and young adults, cardiotoxicity in adults, cardiotoxicity in special populations, and the future of cardio-oncology). Here, the colloquium chairs and all the session chairs briefly summarised what was said at the colloquium. Topics and controversies were reported on behalf of all members of the working group of the International Colloquium on Cardio-Oncology
LSST: from Science Drivers to Reference Design and Anticipated Data Products
(Abridged) We describe here the most ambitious survey currently planned in
the optical, the Large Synoptic Survey Telescope (LSST). A vast array of
science will be enabled by a single wide-deep-fast sky survey, and LSST will
have unique survey capability in the faint time domain. The LSST design is
driven by four main science themes: probing dark energy and dark matter, taking
an inventory of the Solar System, exploring the transient optical sky, and
mapping the Milky Way. LSST will be a wide-field ground-based system sited at
Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m
effective) primary mirror, a 9.6 deg field of view, and a 3.2 Gigapixel
camera. The standard observing sequence will consist of pairs of 15-second
exposures in a given field, with two such visits in each pointing in a given
night. With these repeats, the LSST system is capable of imaging about 10,000
square degrees of sky in a single filter in three nights. The typical 5
point-source depth in a single visit in will be (AB). The
project is in the construction phase and will begin regular survey operations
by 2022. The survey area will be contained within 30,000 deg with
, and will be imaged multiple times in six bands, ,
covering the wavelength range 320--1050 nm. About 90\% of the observing time
will be devoted to a deep-wide-fast survey mode which will uniformly observe a
18,000 deg region about 800 times (summed over all six bands) during the
anticipated 10 years of operations, and yield a coadded map to . The
remaining 10\% of the observing time will be allocated to projects such as a
Very Deep and Fast time domain survey. The goal is to make LSST data products,
including a relational database of about 32 trillion observations of 40 billion
objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures
available from https://www.lsst.org/overvie
Pain-causing stinging nettle toxins target TMEM233 to modulate NaV1.7 function
Voltage-gated sodium (NaV) channels are critical regulators of neuronal excitability and are targeted by many toxins that directly interact with the pore-forming α subunit, typically via extracellular loops of the voltage-sensing domains, or residues forming part of the pore domain. Excelsatoxin A (ExTxA), a pain-causing knottin peptide from the Australian stinging tree Dendrocnide excelsa, is the first reported plant-derived NaV channel modulating peptide toxin. Here we show that TMEM233, a member of the dispanin family of transmembrane proteins expressed in sensory neurons, is essential for pharmacological activity of ExTxA at NaV channels, and that co-expression of TMEM233 modulates the gating properties of NaV1.7. These findings identify TMEM233 as a previously unknown NaV1.7-interacting protein, position TMEM233 and the dispanins as accessory proteins that are indispensable for toxin-mediated effects on NaV channel gating, and provide important insights into the function of NaV channels in sensory neurons
Solar System Objects Observed in the SDSS Commissioning Data
We discuss measurements of the properties of about 10,000 asteroids detected
in 500 deg2 of sky in the Sloan Digital Sky Survey (SDSS) commissioning data.
The moving objects are detected in the magnitude range 14 < r < 21.5, with a
baseline of 5 minutes. Extensive tests show that the sample is at least 98%
complete, with the contamination rate of less than 3%.
We find that the size distribution of asteroids resembles a broken power-law,
independent of the heliocentric distance: D^{-2.3} for 0.4 km < D < 5 km, and
D^{-4} for 5 km < D < 40 km. As a consequence of this break, the number of
asteroids with r < 21.5 is ten times smaller than predicted by extrapolating
the power-law relation observed for brighter asteroids (r < 18). The observed
counts imply that there are about 530,000 objects with D>1 km in the asteroid
belt, or about four times less than previous estimates.
The distribution of main belt asteroids in the 4-dimensional SDSS color space
is bimodal, and the two groups can be associated with S (rocky) and C
(carbonaceous) asteroids. A strong bimodality is also seen in the heliocentric
distribution of asteroids and suggests the existence of two distinct belts: the
inner rocky belt, about 1 AU wide (FWHM) and centered at R~2.8 AU, and the
outer carbonaceous belt, about 0.5 AU wide and centered at R~3.2 AU. The colors
of Hungarias, Mars crossers, and near-Earth objects are more similar to the
C-type than to S-type asteroids, suggesting that they originate in the outer
belt. (abridged).Comment: 89 pages, 31 figures, submitted to A
TESS Hunt for Young and Maturing Exoplanets (THYME) IX: a 27 Myr extended population of Lower-Centaurus Crux with a transiting two-planet system
We report the discovery and characterization of a nearby (~ 85 pc), older (27
+/- 3 Myr), distributed stellar population near Lower-Centaurus-Crux (LCC),
initially identified by searching for stars co-moving with a candidate
transiting planet from TESS (HD 109833; TOI 1097). We determine the association
membership using Gaia kinematics, color-magnitude information, and rotation
periods of candidate members. We measure it's age using isochrones,
gyrochronology, and Li depletion. While the association is near known
populations of LCC, we find that it is older than any previously found LCC
sub-group (10-16 Myr), and distinct in both position and velocity. In addition
to the candidate planets around HD 109833 the association contains four
directly-imaged planetary-mass companions around 3 stars, YSES-1, YSES-2, and
HD 95086, all of which were previously assigned membership in the younger LCC.
Using the Notch pipeline, we identify a second candidate transiting planet
around HD 109833. We use a suite of ground-based follow-up observations to
validate the two transit signals as planetary in nature. HD 109833 b and c join
the small but growing population of <100 Myr transiting planets from TESS. HD
109833 has a rotation period and Li abundance indicative of a young age (< 100
Myr), but a position and velocity on the outskirts of the new population, lower
Li levels than similar members, and a CMD position below model predictions for
27 Myr. So, we cannot reject the possibility that HD 109833 is a young field
star coincidentally nearby the population.Comment: 23 pages, 15 figures, Accepted for publication in A
- âŠ