170,176 research outputs found
Self-organising an indoor location system using a paintable amorphous computer
No full textThis thesis investigates new methods for self-organising a precisely defined pattern of intertwined number sequences which may be used in the rapid deployment of a passive indoor positioning system's infrastructure.A future hypothetical scenario is used where computing particles are suspended in paint and covered over a ceiling. A spatial pattern is then formed over the covered ceiling. Any small portion of the spatial pattern may be decoded, by a simple camera equipped device, to provide a unique location to support location-aware pervasive computing applications.Such a pattern is established from the interactions of many thousands of locally connected computing particles that are disseminated randomly and densely over a surface, such as a ceiling. Each particle has initially no knowledge of its location
or network topology and shares no synchronous clock or memory with any other particle.The challenge addressed within this thesis is how such a network of computing particles that begin in such an initial state of disarray and ignorance can, without outside intervention or expensive equipment, collaborate to create a relative coordinate system. It shows how the coordinate system can be created to be coherent, even in the face of obstacles, and closely represent the actual shape of the networked surface itself. The precision errors incurred during the propagation of the coordinate system are identified and the distributed algorithms used to avoid this error are explained and demonstrated through simulation.A new perimeter detection algorithm is proposed that discovers network edges and other obstacles without the use of any existing location knowledge. A new distributed localisation algorithm is demonstrated to propagate a relative coordinate system throughout the network and remain free of the error introduced by the network perimeter that is normally seen in non-convex networks. This localisation algorithm operates without prior configuration or calibration, allowing the coordinate system to be deployed without expert manual intervention or on networks that are otherwise inaccessible.The painted ceiling's spatial pattern, when based on the proposed localisation algorithm, is discussed in the context of an indoor positioning system
Inorganic carbon physiology underpins macroalgal responses to elevated CO2
No full textBeneficial effects of CO2 on photosynthetic organisms will be a key driver of ecosystem change under ocean acidification. Predicting the responses of macroalgal species to ocean acidification is complex, but we demonstrate that the response of assemblages to elevated CO2 are correlated with inorganic carbon physiology. We assessed abundance patterns and a proxy for CO2:HCO3(-) use (δ(13)C values) of macroalgae along a gradient of CO2 at a volcanic seep, and examined how shifts in species abundance at other Mediterranean seeps are related to macroalgal inorganic carbon physiology. Five macroalgal species capable of using both HCO3(-) and CO2 had greater CO2 use as concentrations increased. These species (and one unable to use HCO3(-)) increased in abundance with elevated CO2 whereas obligate calcifying species, and non-calcareous macroalgae whose CO2 use did not increase consistently with concentration, declined in abundance. Physiological groupings provide a mechanistic understanding that will aid us in determining which species will benefit from ocean acidification and why.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Constraining the carbon budgets of croplands with Earth observation data
No full textCropland management practices have traditionally focused on maximising the production
of food, feed and fibre. However, croplands also provide valuable regulating ecosystem
services, including carbon (C) storage in soil and biomass. Consequently, management
impacts the extents to which croplands act as sources or sinks of atmospheric carbon
dioxide (CO2). And so, reliable information on cropland ecosystem C fluxes and yields
are essential for policy-makers concerned with climate change mitigation and food
security.
Eddy-covariance (EC) flux towers can provide observations of net ecosystem exchanges
(NEE) of CO2 within croplands, however the tower sites are temporally and spatially
sparse. Process-based crop models simulate the key biophysical mechanisms within
cropland ecosystems, including the management impacts, crop cultivar, soil and climate
on crop C dynamics. The models are therefore a powerful tool for diagnosing and
forecasting C fluxes and yield. However, crop model spatial upscaling is often limited by
input data (including meteorological drivers and management), parameter uncertainty and
model complexity. Earth observation (EO) sensors can provide regular estimates of crop
condition over large extents. Therefore, EO data can be used within data assimilation (DA)
schemes to parameterise and constrain models.
Research presented in this thesis explores the key challenges associated with crop model
upscaling. First, fine-scale (20-50 m) EO-derived data, from optical and radar sensors, is
assimilated into the Soil-Plant-Atmosphere crop (SPAc) model. Assimilating all EO data
enhanced the simulation of daily C exchanges at multiple European crop sites. However,
the individually assimilation of radar EO data (as opposed to combined with optical data)
resulted in larger improvements in the C fluxes simulation. Second, the impacts of reduced
model complexity and driver resolution on crop photosynthesis estimates are investigated.
The simplified Aggregated Canopy Model (ACM) – estimating daily photosynthesis using
coarse-scale (daily) drivers – was calibrated using the detailed SPAc model, which
simulates leaf to canopy processes at half-hourly time-steps. The calibrated ACM
photosynthesis had a high agreement with SPAc and local EC estimates. Third, a
model-data fusion framework was evaluated for multi-annual and regional-scale
estimation of UK wheat yields. Aggregated model yield estimates were negatively biased
when compared to official statistics. Coarse-scale (1 km) EO data was also used to
constrain the model simulation of canopy development, which was successful in reducing
the biases in the yield estimates. And fourth, EO spatial and temporal resolution
requirements for crop growth monitoring at UK field-scales was investigated. Errors due
to spatial resolution are quantified by sampling aggregated fine scale EO data on a
per-field basis; whereas temporal resolution error analysis involved re-sampling model
estimates to mimic the observational frequencies of current EO sensors and likely cloud
cover. A minimum EO spatial resolution of around 165 m is required to resolve the
field-scale detail. Monitoring crop growth using EO sensors with a 26-day temporal
resolution results in a mean error of 5%; however, accounting for likely cloud cover
increases this error to 63%
Dataset supporting the publication: "Structure and vibrational spectroscopy of lithium and potassium methanesulfonates" by Parker, Revill-Hivet, Nye and Gutmann, published in Royal Society Open Science 2020
No full textThe dataset comprises the experimental and computational studies that form the basis of the publication: "Structure and vibrational spectroscopy of lithium and potassium methanesulfonates" by Parker, Revill-Hivet, Nye and Gutmann, published in Royal Society Open Science (2020).
The dataset consists of three zip files: "A-Crystallographic_information.zip", "B-Experimental_spectra.zip", "C-CASTEP.zip", .
"A-Crystallographic_information.zip" contains cif files of the structures. These can be read by any text reader or loaded into any suitable program e.g. Jmol (available from: http://jmol.sourceforge.net/ ) to display the structure.
"B-Experimental_spectra.zip" contains the vibrational spectra: infrared, Raman and inelastic neutron scattering (INS), all have a .dat extension and can be viewed with any text reader or can be loaded into programs such as Excel or Origin to display the spectra. The filename is the name of the compound and ends in _IR for infrared, _Raman for Raman and _INS for INS data.
The infrared and Raman data consists of two columns of ASCII data. Column 1 is the energy transfer in wavenumber (cm-1), column 2 is the intensity (Absorbance for the infrared data, arbitrary units for the Raman data). The INS data consists of three columns: column 1 is the energy transfer in wavenumber (cm-1), column 2 is the intensity, S(Q,w) (arbitrary units), and column three is the error bar of the intensity given in column 2. There are three spectra listed sequentially in each file and separated by 0,1,2. The first "0" are the data from the backscattering detectors, "1" are the data from the forward scattering detectors and "2" is the arithmetic average of the forward and back scattering detectors. "2" is the spectrum that is normally displayed and is that shown in the Royal Society Open Science paper and on the INS database.
"C-CASTEP.zip" contains the input (.cell and .param) and output (.castep) from the geometry optimisation using the CASTEP (version 17.21) program. The output file includes the geometry optimised structure.
The CASTEP input files (.cell and .param) and the output files (.castep and .phonon) for the vibrational calculation have the same stem as for the geometry optimisation but have _Efield appended. The .phonon file includes both the transition energies and atomic displacements for all the atoms in each mode.
The .phonon files for the calculations of the isotopomers are also included. These include the mass of the isotopomer in the title
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
A 0.12mm<sup>2</sup> Wien-Bridge Temperature Sensor with 0.1°C (3σ) Inaccuracy from -40°C to 180°C
No full text Resistor-based temperature sensors can achieve much higher resolution and energy efficiency than conventional BJT-based sensors [1], but they typically occupy more area (> 0.25 mm 2 ) and have lower operating temperatures (le 125 {circ} {C}) [2]-[4]. This work describes a 0.12mm 2 resistor-based sensor that uses a Wien-bridge (WB) filter to achieve 0.1 {circ} {C} (3 sigma) inaccuracy from - 40 {circ} {C} to 180 {circ} {C}. Compared to a state-of-the-art WB sensor [4], it occupies 6 × less area and achieves comparable relative accuracy over a 76% wider operating range. Session 10.3 Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
A ±25A Versatile Shunt-Based Current Sensor with 10kHz Bandwidth and ±0.25% Gain Error from -40°C to 85°C Using 2-Current Calibration
No full textAccurate current sensing is critical in many industrial applications, such as battery management and motor control. Precise shunt-based current sensors have been reported with gain errors of less than 1% over the industrial temperature range (-40°C to 85°C) [1]–[4]. However, since they are intended for coulomb counting, their bandwidth is limited to a few tens of Hz, making them unsuitable for battery impedance or motor-current sensing. This paper presents a current sensor with a wide (10kHz) bandwidth and a tunable temperature compensation scheme (TCS), which allows it to be flexibly used with different types of shunts while maintaining high accuracy. A low-cost room-temperature calibration scheme is proposed to optimize gain flatness over temperature by exploiting the shunt's self-heating at large currents. Over the industrial temperature range and a ±25A current range, it achieves state-of-the-art gain error (±0.25%) with both low-cost PCB and stable metal-alloy shunts.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
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