Papers by Philip E Taylor
Ecological Applications, 2016
Distributions of foliar nutrients across forest canopies can give insight into their plant functi... more Distributions of foliar nutrients across forest canopies can give insight into their plant functional diversity and improve our understanding of biogeochemical cycling. We used airborne remote sensing and partial least squares regression to quantify canopy foliar nitrogen (foliar N) across ~164 km(2) of wet lowland tropical forest in the Osa Peninsula, Costa Rica. We determined the relative influence of climate and topography on the observed patterns of foliar N using a gradient boosting model technique. At a local scale, where climate and substrate were constant, we explored the influence of slope position on foliar N by quantifying foliar N on remnant terraces, their adjacent slopes, and knife-edged ridges. In addition, we climbed and sampled 540 trees and analyzed foliar N in order to quantify the role of species identity (phylogeny) and environmental factors in predicting foliar N. Observed foliar N heterogeneity reflected environmental factors working at multiple spatial scales. Across the larger landscape, elevation and precipitation had the highest relative influence on predicting foliar N (30% and 24%), followed by soils (15%), site exposure (9%), compound topographic index (8%), substrate (6%), and landscape dissection (6%). Phylogeny explained ~75% of the variation in the field collected foliar N data, suggesting that phylogeny largely underpins the response to the environmental factors. Taken together, these data suggest that a large fraction of the variance in foliar N across the landscape is proximately driven by species composition, though ultimately this is likely a response to abiotic factors such as climate and topography. Future work should focus on the mechanisms and feedbacks involved, and how shifts in climate may translate to changes in forest function.
For seasonal migrants, logistical constraints have often limited conservation efforts to improvin... more For seasonal migrants, logistical constraints have often limited conservation efforts to improving survival and reproduction during the breeding season only. Yet, mounting empirical evidence suggests that events occurring throughout the migratory life cycle can critically alter the demography of many migrant species. Herein, we build upon recent syntheses of avian migration research to review the role of non-breeding seasons in
Movement Ecology, 2016
Island breeding birds present an ideal system for studying migratory movements in passerines beca... more Island breeding birds present an ideal system for studying migratory movements in passerines because their populations are clearly demarcated, and individuals must depart on migration from a single location. The Ipswich Sparrow (Paserculus sandwichensis princeps) is a subspecies of the Savannah Sparrow that breeds exclusively on Sable Island, Nova Scotia, Canada and winters along the Atlantic coast of North America. We used a network of 34 automated VHF telemetry receivers to track radio-tagged adult and juvenile Ipswich Sparrows from their breeding island southward through the first half of their fall migratory journey. We compared adult to juvenile timing and routes. We show that juveniles leave the island approximately 24 days prior to adults and remain temporally separated from them during migration through Nova Scotia. Juveniles have different overwater orientations that result in migratory routes with shorter ocean crossings and a longer overall distance travelled compared to adults. Juveniles also have more frequent and longer stopovers, and displayed some reverse migration. We demonstrate that migratory routes differ between adults and juveniles, suggesting that routes change as individuals age, possibly through learning or social interactions. These differential routes also suggest that sparrows experience risk in different ways with juveniles selecting shorter overwater flights with less navigational risk at the cost of increased time spent in migration.
Biology letters, 2015
Using a broad-scale automated telemetry array, we explored post-fledging movements of blackpoll w... more Using a broad-scale automated telemetry array, we explored post-fledging movements of blackpoll warblers breeding in Atlantic Canada. We sought to determine the full spatial scale of post-fledging dispersal, to assess support for three hypotheses for regional-scale post-fledging movement, and to determine whether learning influenced movement during this period. We demonstrated that both young and adults moved over distances more than 200 km prior to initiating migration. Adults moved southwest, crossing the Gulf of Maine (GOM), consistent with the commencement of migration hypothesis. Hatch-year birds exhibited less directional movements constrained geographically by the GOM. Their movements were most consistent with exploration hypotheses-that young birds develop a regional-scale map to aid in habitat selection, natal dispersal and subsequent migrations.
18th International Conference and Exhibition on Electricity Distribution (CIRED 2005), 2005
Nanoscale, Jan 15, 2015
Atomic scale features of polyvinylidene fluoride molecules (PVDF) were observed with aberration c... more Atomic scale features of polyvinylidene fluoride molecules (PVDF) were observed with aberration corrected transmission electron microscopy. Thin, self-supporting PVDF nanofibers were used to create images that show conformations and relative locations of atoms in segments of polymer molecules, particularly segments near the surface of the nanofiber. Rows of CF2 atomic groups, at 0.25 nm intervals, which marked the paths of segments of the PVDF molecules, were seen. The fact that an electron microscope image of a segment of a PVDF molecule depended upon the particular azimuthal direction, along which the segment was viewed, enabled observation of twist around the molecular axis. The 0.2 nm side-by-side distance between the two fluorine atoms attached to the same carbon atom was clearly resolved. Morphological and chemical changes produced by energetic electrons, ranging from no change to fiber scission, over many orders of magnitude of electrons per unit area, promise quantitative ne...
International Journal of Mass Spectrometry and Ion Processes, 1995
The structure and contents of a raw data output file are proposed to provide isotope mass spectro... more The structure and contents of a raw data output file are proposed to provide isotope mass spectrometrists with a common basis for data exchange. This applies to thermal ionisation mass spectrometry and to gas source mass spectrometry. The definition of the contents of this file is based on the experience gained in three different laboratories under the constraints of the very different tasks these laboratories have to fulfil. The information contained in this file enables the analyst to evaluate critically and completely the measurement data, establishing the necessary flexibility by providing all the information needed for calculating the final result.
The First IEEE/RAS-EMBS International Conference on Biomedical Robotics and Biomechatronics, 2006. BioRob 2006., 2006
Head movement is one of the most effective hands-free control modes for powered wheelchairs. It p... more Head movement is one of the most effective hands-free control modes for powered wheelchairs. It provides the necessary mobility assistance to severely disabled people and can be used to replace the joystick directly. In this paper, we describe the development of Bayesian neural networks for the classification of head movement commands in a hands-free wheelchair control system. Bayesian neural networks allow strong generalisation of head movement classifications during the training phase and do not require a validation data set. Various advanced optimisation training algorithms are explored. Experimental results show that Bayesian neural networks can be developed to classify head movement commands by abled and disabled people accurately with limited training data.
The molecular architecture of polymer electrolyte membranes (PEM), which consist of hydrophobic a... more The molecular architecture of polymer electrolyte membranes (PEM), which consist of hydrophobic and hydrophilic segments, leads to its own self-assembled structure through a partial phase segregation. Controlling these structures is necessary for improving the performance of fuel cells. We have used computer simulation to analyze the relationship between the hydrophilic cluster structure and the parameters describing the pendant side chains in dry Nafion-like materials. We investigate the morphology of a dry PEM system within different coarse-grained models: a free-proton model, a dipolar model for side chains, and a branched-chain model. We conclude that the free-proton model, where the proton-proton correlations are decoupled from the sulfonate-sulfonate correlations, has the potential to explain the experimentally observed conformational structures of PEM. We find that the geometry of domains with a high concentration of sulfonate groups depends only weakly on the form of the dis...
International Journal of Mass Spectrometry and Ion Processes, 1997
The isotope abundance ratio of lithium in the Li isotopic reference material IRMM-016 was redeter... more The isotope abundance ratio of lithium in the Li isotopic reference material IRMM-016 was redetermined by thermal ionisation mass spectrometry by means of synthetic isotope mixtures. This resulted in an absolute ratio n(6Li)/n(TLi) of 0.08212 -+ 0.00028, and corresponding isotope abundances of 7.589 --+ 0.024 amount % 6Li, 92.411 -0.024 amount % 7Li and an atomic weight of lithium of 6.94005 + 0.00024. Uncertainties are expanded uncertainties using a coverage factor of two. © 1997 Elsevier Science B.V.
An approach to set up an appropriate and optimal national infrastructure for measurements related... more An approach to set up an appropriate and optimal national infrastructure for measurements related to quality of life in Slovenia is described. It is based on an analysis of the needs of the global society, of the national needs and priorities and on the national capabilities. The implementation of the conclusions into practice has started. As in general measurements in
Movement ecology, 2015
Given that winds encountered on migration could theoretically double or half the energy expenditu... more Given that winds encountered on migration could theoretically double or half the energy expenditure of aerial migrants, there should be strong selection on behaviour in relation to wind conditions aloft. However, evidence suggests that juvenile songbirds are less choosy about wind conditions at departure relative to adults, potentially increasing energy expenditure during flight. To date, there has yet to be a direct comparison of flight efficiency between free-living adult and juvenile songbirds during migration in relation to wind conditions aloft, likely because of the challenges of following known aged individual songbirds during flight. We used an automated digital telemetry array to compare the flight efficiency of adult and juvenile Savannah sparrows (Passerculus sandwichensis) as they flew nearly 100 km during two successive stages of their fall migration; a departure flight from their breeding grounds out over the ocean and then a migratory flight along a coast. Using a mul...
An ideal dielectric is one that reversibly stores a large amount of energy when exposed to a mode... more An ideal dielectric is one that reversibly stores a large amount of energy when exposed to a modest electric field. We have used theory and molecular dynamics simulation as an aid to the development of polymeric materials with favorable properties for energy storage with low dielectric losses. Because the stored energy in a capacitor resides mostly in the energy of distortion of the molecular bonds within the material, it is necessary to optimize the size of the deformable polar units. We achieve this by modeling some of the copolymers of polyvinylidene fluoride, and identifying the preferred density and nature of the cross-linking that pins certain regions of the polymer chains to prevent their rotation when exposed to fields. We then relate this to the electrostatic interactions within chains and between chains in order to take account of the depolarizing fields. We find the optimal length of chain between pinning points to be a function of the applied field strength, and to vary ...
Conference Digest Conference on Precision Electromagnetic Measurements, 2002
The structural and stoichiometric characterisations of silicon crystals are reported to find the ... more The structural and stoichiometric characterisations of silicon crystals are reported to find the origin of a molar volume discrepancy. The target of reproducing this anomaly was achieved and an hypothesis is proposed.
PloS one, 2015
The use of counts of unmarked migrating animals to monitor long term population trends assumes in... more The use of counts of unmarked migrating animals to monitor long term population trends assumes independence of daily counts and a constant rate of detection. However, migratory stopovers often last days or weeks, violating the assumption of count independence. Further, a systematic change in stopover duration will result in a change in the probability of detecting individuals once, but also in the probability of detecting individuals on more than one sampling occasion. We tested how variation in stopover duration influenced accuracy and precision of population trends by simulating migration count data with known constant rate of population change and by allowing daily probability of survival (an index of stopover duration) to remain constant, or to vary randomly, cyclically, or increase linearly over time by various levels. Using simulated datasets with a systematic increase in stopover duration, we also tested whether any resulting bias in population trend could be reduced by model...
Proceedings of 20th Biennial Conference on Precision Electromagnetic Measurements, 1996
Molar masses M and densities ρ of silicon in 1 kg Si almost perfect single crystals have been mea... more Molar masses M and densities ρ of silicon in 1 kg Si almost perfect single crystals have been measured over the last several years to very small uncertainties in order to improve our knowledge of the Avogadro constant. Combining both is an excellent way to determine the molar volume of silicon. Small variations in isotopic composition and hence in molar
1998 Conference on Precision Electromagnetic Measurements Digest (Cat. No.98CH36254), 1998
ABSTRACT The determination of the correction factors for isotope fractionations for measurements ... more ABSTRACT The determination of the correction factors for isotope fractionations for measurements of amount ratios of silicon-bearing ions has been undertaken in order to define correction equations for the isotope amount ratios measured on the SiF3+ ion beams used in the re-determinations of the Avogadro constant
International Journal of Mass Spectrometry and Ion Processes, 1997
Gas adsorption in the mass spectrometer inlet system (equipped with molecular leak) causes a devi... more Gas adsorption in the mass spectrometer inlet system (equipped with molecular leak) causes a deviation from linearity of the measured lnR i/1 data versus time, which affects the extrapolation to time t = 0 required to obtain the isotope amount ratios of a sample.
International Journal of Mass Spectrometry and Ion Processes, 1997
Mass spectrometric measurements were carried out on a CO2 sample prepared by mixing known amounts... more Mass spectrometric measurements were carried out on a CO2 sample prepared by mixing known amounts of 'natural' CO2 with CO2 enriched in 13C and, to a lesser extent, in 170 and 180. The sample was in isotopic disequilibrium, i.e. with the isotopic species distribution not obeying the statistical probability. The results indicate that isotope scrambling reactions occur during the measurement which tend to shift the gas isotopic composition towards the equilibrium. The isotope exchange reactions take place via gas adsorption in the mass spectrometer inlet system.
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Papers by Philip E Taylor