1,741 research outputs found
Towards Real-Time Information Processing of Sensor Network Data using Computationally Efficient Multi-output Gaussian Processes
In this paper, we describe a novel, computationally efficient algorithm that facilitates the autonomous acquisition of readings from sensor networks (deciding when and which sensor to acquire readings from at any time), and which can, with minimal domain knowledge, perform a range of information processing tasks including modelling the accuracy of the sensor readings, predicting the value of missing sensor readings, and predicting how the monitored environmental variables will evolve into the future. Our motivating scenario is the need to provide situational awareness support to first responders at the scene of a large scale incident, and to this end, we describe a novel iterative formulation of a multi-output Gaussian process that can build and exploit a probabilistic model of the environmental variables being measured (including the correlations and delays that exist between them). We validate our approach using data collected from a network of weather sensors located on the south coast of England
Information Agents for Pervasive Sensor Networks
In this paper, we describe an information agent, that resides on a mobile computer or personal digital assistant (PDA), that can autonomously acquire sensor readings from pervasive sensor networks (deciding when and which sensor to acquire readings from at any time). Moreover, it can perform a range of information processing tasks including modelling the accuracy of the sensor readings, predicting the value of missing sensor readings, and predicting how the monitored environmental parameters will evolve into the future. Our motivating scenario is the need to provide situational awareness support to first responders at the scene of a large scale incident, and we describe how we use an iterative formulation of a multi-output Gaussian process to build a probabilistic model of the environmental parameters being measured by local sensors, and the correlations and delays that exist between them. We validate our approach using data collected from a network of weather sensors located on the south coast of England
Drosophila EB1 is important for proper assembly, dynamics, and positioning of the mitotic spindle
EB1 is an evolutionarily conserved protein that localizes to the plus ends of growing microtubules. In yeast, the EB1 homologue (BIM1) has been shown to modulate microtubule dynamics and link microtubules to the cortex, but the functions of metazoan EB1 proteins remain unknown. Using a novel preparation of the Drosophila S2 cell line that promotes cell attachment and spreading, we visualized dynamics of single microtubules in real time and found that depletion of EB1 by RNA-mediated inhibition (RNAi) in interphase cells causes a dramatic increase in nondynamic microtubules (neither growing nor shrinking), but does not alter overall microtubule organization. In contrast, several defects in microtubule organization are observed in RNAi-treated mitotic cells, including a drastic reduction in astral microtubules, malformed mitotic spindles, defocused spindle poles, and mispositioning of spindles away from the cell center. Similar phenotypes were observed in mitotic spindles of Drosophila embryos that were microinjected with anti-EB1 antibodies. In addition, live cell imaging of mitosis in Drosophila embryos reveals defective spindle elongation and chromosomal segregation during anaphase after antibody injection. Our results reveal crucial roles for EB1 in mitosis, which we postulate involves its ability to promote the growth and interactions of microtubules within the central spindle and at the cell cortex
Autocatalytic plume pinch-off
A localized source of buoyancy flux in a non-reactive fluid medium creates a
plume. The flux can be provided by either heat, a compositional difference
between the fluid comprising the plume and its surroundings, or a combination
of both. For autocatalytic plumes produced by the iodate-arsenous acid
reaction, however, buoyancy is produced along the entire reacting interface
between the plume and its surroundings. Buoyancy production at the moving
interface drives fluid motion, which in turn generates flow that advects the
reaction front. As a consequence of this interplay between fluid flow and
chemical reaction, autocatalytic plumes exhibit a rich dynamics during their
ascent through the reactant medium. One of the more interesting dynamical
features is the production of an accelerating vortical plume head that in
certain cases pinches-off and detaches from the upwelling conduit. After
pinch-off, a new plume head forms in the conduit below, and this can lead to
multiple generations of plume heads for a single plume initiation. We
investigated the pinch-off process using both experimentation and simulation.
Experiments were performed using various concentrations of glycerol, in which
it was found that repeated pinch-off occurs exclusively in a specific
concentration range. Autocatalytic plume simulations revealed that pinch-off is
triggered by the appearance of accelerating flow in the plume conduit.Comment: 10 figures. Accepted for publication in Phys Rev E. See also
http://www.physics.utoronto.ca/nonlinear/papers_chemwave.htm
Natural versus forced convection in laminar starting plumes
A starting plume or jet has a well-defined, evolving head that is driven
through the surrounding quiescent fluid by a localized flux of either buoyancy
or momentum, or both. We studied the scaling and morphology of starting plumes
produced by a constant flux of buoyant fluid from a small, submerged outlet.
The plumes were laminar and spanned a wide range of plume Richardson numbers
Ri. Ri is the dimensionless ratio of the buoyancy forces to inertial effects,
and is thus our measurements crossed over the transition between
buoyancy-driven plumes and momentum-driven jets. We found that the ascent
velocity of the plume, nondimensionalized by Ri, exhibits a power law
relationship with Re, the Reynolds number of the injected fluid in the outlet
pipe. We also found that as the threshold between buoyancy-driven and
momentum-driven flow was crossed, two distinct types of plume head mophologies
existed: confined heads, produced in the Ri > 1 regime, and dispersed heads,
which are found in the Ri < 1 regime. Head dispersal is caused by a breakdown
of overturning motion in the head, and a local Kelvin-Helmholtz instability on
the exterior of the plume.Comment: 8 pages, 8 figures, accepted for publication in Physics of Fluids
(final version with corrections
Spindle microtubules in flux
Accurate and timely chromosome segregation is a task performed within meiotic and mitotic cells by a specialized force-generating structure - the spindle. This micromachine is constructed from numerous proteins, most notably the filamentous microtubules that form a structural framework for the spindle and also transmit forces through it. Poleward flux is an evolutionarily conserved mechanism used by spindle microtubules both to move chromosomes and to regulate spindle length. Recent studies have identified a microtubule-depolymerizing kinesin as a key force-generating component required for flux. On the basis of these findings, we propose a new model for flux powered by a microtubule-disassembly mechanism positioned at the spindle pole. In addition, we use the flux model to explain the results of spindle manipulation experiments to illustrate the importance of flux for proper chromosome positioning
The Fog signaling pathway: Insights into signaling in morphogenesis
Epithelia form the building blocks of many tissue and organ types. Epithelial cells often form a contiguous 2-dimensional sheet that is held together by strong adhesions. The mechanical properties conferred by these adhesions allow the cells to undergo dramatic three-dimensional morphogenetic movements while maintaining cell–cell contacts during embryogenesis and post-embryonic development. The Drosophila Folded gastrulation pathway triggers epithelial cell shape changes that drive gastrulation and tissue folding and is one of the most extensively studied examples of epithelial morphogenesis. This pathway has yielded key insights into the signaling mechanisms and cellular machinery involved in epithelial remodeling. In this review, we discuss principles of morphogenesis and signaling that have been discovered through genetic and cell biological examination of this pathway. We also consider various regulatory mechanisms and the system's relevance to mammalian development. We propose future directions that will continue to broaden our knowledge of morphogenesis across taxa
Prevention of sexual transmission of Ebola in Liberia through a national semen testing and counselling programme for survivors: an analysis of Ebola virus RNA results and behavioural data
Background Ebola virus has been detected in semen of Ebola virus disease survivors after recovery. Liberia’s Men’s
Health Screening Program (MHSP) off ers Ebola virus disease survivors semen testing for Ebola virus. We present
preliminary results and behavioural outcomes from the fi rst national semen testing programme for Ebola virus.
Methods The MHSP operates out of three locations in Liberia: Redemption Hospital in Montserrado County, Phebe
Hospital in Bong County, and Tellewoyan Hospital in Lofa County. Men aged 15 years and older who had an Ebola
treatment unit discharge certifi cate are eligible for inclusion. Participants’ semen samples were tested for Ebola virus
RNA by real-time RT-PCR and participants received counselling on safe sexual practices. Participants graduated after
receiving two consecutive negative semen tests. Counsellors collected information on sociodemographics and sexual
behaviours using questionnaires administered at enrolment, follow up, and graduation visits. Because the programme
is ongoing, data analysis was restricted to data obtained from July 7, 2015, to May 6, 2016.
Findings As of May 6, 2016, 466 Ebola virus disease survivors had enrolled in the programme; real-time RT-PCR
results were available from 429 participants. 38 participants (9%) produced at least one semen specimen that tested
positive for Ebola virus RNA. Of these, 24 (63%) provided semen specimens that tested positive 12 months or longer
after Ebola virus disease recovery. The longest interval between discharge from an Ebola treatment unit and collection
of a positive semen sample was 565 days. Among participants who enrolled and provided specimens more than
90 days since their Ebola treatment unit discharge, men older than 40 years were more likely to have a semen sample
test positive than were men aged 40 years or younger (p=0·0004). 84 (74%) of 113 participants who reported not using
a condom at enrolment reported using condoms at their fi rst follow-up visit (p<0·0001). 176 (46%) of 385 participants
who reported being sexually active at enrolment reported abstinence at their follow-up visit (p<0·0001).
Interpretation Duration of detection of Ebola virus RNA by real-time RT-PCR varies by individual and might be
associated with age. By combining behavioural counselling and laboratory testing, the Men’s Health Screening
Program helps male Ebola virus disease survivors understand their individual risk and take appropriate measures to
protect their sexual partners
You\u27re Suing Me? Best Fair Use & Copyright Practices
Do you teach? Do you publish? Do you know how to exercise your fair use rights?
This panel discussion focuses on fair use and copyright practices.
Panels include:
The Basics – Get a general overview of fair use and methods for making fair use decisions, including the four factors and best practices.
Blackboard Behavior! - Learn about best practices when building course content and assignments in Blackboard. Find out about the TEACH Act and how it impacts teaching online.
Good Intentions: Fair Use, Images, and ETDs – Learn about the fair use guidelines pertaining to the use of images in research can be used to help determine if the use of the images would be appropriate.
Fair Use for Digitized Materials - Learn how to identify how fair use may apply to digitized materials and the way to utilize them in your work
Quantifying the UV-continuum slopes of galaxies to z ˜ 10 using deep Hubble+Spitzer/IRAC observations
Measurements of the UV-continuum slopes β provide valuable information on the physical properties of galaxies forming in the early universe, probing the dust reddening, age, metal content, and even the escape fraction. While constraints on these slopes generally become more challenging at higher redshifts as the UV-continuum shifts out of the Hubble Space Telescope bands (particularly at z > 7), such a characterization actually becomes abruptly easier for galaxies in the redshift window z = 9.5-10.5 due to the Spitzer/Infrared Array Camera 3.6 μm-band probing the rest-UV continuum and the long wavelength baseline between this Spitzer band and the Hubble Hf160w band. Higher S/N constraints on β are possible at z ˜ 10 than at z = 8. Here, we take advantage of this opportunity and five recently discovered bright z = 9.5-10.5 galaxies to present the first measurements of the mean β for a multi-object sample of galaxy candidates at z ˜ 10. We find the measured βobs's of these candidates are -2.1 ± 0.3 ± 0.2 (random and systematic), only slightly bluer than the measured β's (βobs ≈ -1.7) at 3.5 < z < 7.5 for galaxies of similar luminosities. Small increases in the stellar ages, metallicities, and dust content of the galaxy population from z ˜ 10 to z ˜ 7 could easily explain the apparent evolution in β
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