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... 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.
Research Interests:
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... 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
Research Interests:
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... 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.
Research Interests:
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... 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.
Research Interests:
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... 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...
Research Interests:
Research Interests:
Research Interests:
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... 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...
Research Interests:
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... 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
Research Interests:
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... 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...
Research Interests:
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... 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 ...
Research Interests:
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.
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... 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...
Research Interests:
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... 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
Research Interests:
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... 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
Research Interests:
Research Interests:
Research Interests:
Research Interests:
ABSTRACT PTB, IRMM, IMGC, NRLM and CSIRO have been cooperating on improving our knowledge of the Avogadro constant NA and therefore of the molar volume of silicon. This is done by performing measurements of the interatomic distance a0 (in... more
ABSTRACT PTB, IRMM, IMGC, NRLM and CSIRO have been cooperating on improving our knowledge of the Avogadro constant NA and therefore of the molar volume of silicon. This is done by performing measurements of the interatomic distance a0 (in metre) of the Si atoms in a near-perfect Si single crystal, of the density ρ (in kg/m3) of such a crystal and of the molar mass M (in kg/mol) of the Si in the crystal. This paper proposes that, rather than assume perfection of the artefacts (i.e. the single crystals which could include some with voids) and cast doubt on the reliability of the measurement procedures for a0, ρ and M (as a result of observed deviations), it seems to be the other way round: the measurement procedures seem to be more reliable at the stated (small) uncertainty than the variations observed for the molar volume. The measurement procedures with their small uncertainties, enabled to uncover real differences in the crystals
Research Interests:
Research Interests:
Tropical forests store large amounts of carbon in tree biomass, although the environmental controls on forest carbon stocks remain poorly resolved. Emerging airborne remote sensing techniques offer a powerful approach to understand how... more
Tropical forests store large amounts of carbon in tree biomass, although the environmental controls on forest carbon stocks remain poorly resolved. Emerging airborne remote sensing techniques offer a powerful approach to understand how aboveground carbon density (ACD) varies across tropical landscapes. In this study, we evaluate the accuracy of the Carnegie Airborne Observatory (CAO) Light Detection and Ranging (LiDAR) system to detect top-of-canopy tree height (TCH) and ACD across the Osa Peninsula, Costa Rica. LiDAR and field-estimated TCH and ACD were highly correlated across a wide range of forest ages and types. Top-of-canopy height (TCH) reached 67 m, and ACD surpassed 225 Mg C ha-1, indicating both that airborne CAO LiDAR-based estimates of ACD are accurate in tall, high-biomass forests and that the Osa Peninsula harbors some of the most carbon-rich forests in the Neotropics. We also examined the relative influence of lithologic, topoedaphic and climatic factors on regional p...
Research Interests:
Research Interests:
Research Interests:
Many fundamental aspects of migration remain a mystery, largely due to our inability to follow small animals over vast spatial areas. For more than 50 years, it has been hypothesized that, during autumn migration, blackpoll warblers... more
Many fundamental aspects of migration remain a mystery, largely due to our inability to follow small animals over vast spatial areas. For more than 50 years, it has been hypothesized that, during autumn migration, blackpoll warblers (Setophaga striata) depart northeastern North America and undertake a non-stop flight over the Atlantic Ocean to either the Greater Antilles or the northeastern coast of South America. Using miniaturized light-level geolocators, we provide the first irrefutable evidence that the blackpoll warbler, a 12 g boreal forest songbird, completes an autumn transoceanic migration ranging from 2270 to 2770 km (mean ± s.d.: 2540 ± 257) and requiring up to 3 days (62 h ± 10) of non-stop flight. This is one of the longest non-stop overwater flights recorded for a songbird and confirms what has long been believed to be one of the most extraordinary migratory feats on the planet.
Research Interests:
Research Interests:
Cytochrome P-450scc as isolated is a cholesterol-depleted low-spin haemoprotein; addition of cholesterol results in formation of a high-spin complex. Cytochrome P-450scc--cholesterol is a one-electron acceptor on titration with NADPH.... more
Cytochrome P-450scc as isolated is a cholesterol-depleted low-spin haemoprotein; addition of cholesterol results in formation of a high-spin complex. Cytochrome P-450scc--cholesterol is a one-electron acceptor on titration with NADPH. Cytochrome P-450scc--cholesterol can be anaerobically reduced to the ferrous state which, on oxygenation, forms an oxygenated cytochrome P-450scc--cholesterol complex. This oxygenated complex in the absence of adrenodoxin autoxidises to ferric cytochrome P-450scc--cholesterol without oxidation of cholesterol. The decay of the oxygenated complex is first-order, k = 9.3 X 10(-3) S-1 at 4 degrees C. The rate of autoxidation is influenced by pH, ionic strength and the chemical nature of bound sterol. The activation energy of autoxidation is 75 kJ mol-1. Addition of equimolar amounts of adrenodoxin to cytochrome P-450scc--cholesterol followed by stoichiometric reduction under anaerobic conditions and subsequent oxygenation, allows single catalytic turnover ...
Research Interests:
Research Interests:
Research Interests:
Research Papers, part of a Special Feature on Bird Conservation in the Boreal Forest: Is there a Case for Resilience? Survival of Adult Songbirds in Boreal Forest Landscapes Fragmented by Clearcuts and Natural Openings Taux de survie d'oiseaux adultes dans des paysages forestiers boréaux fragment...more
There exists little information on demographic responses of boreal songbirds to logging. We conducted a 4-yr (2003-2006) songbird mark-recapture study in western Newfoundland, where land cover is a naturally heterogeneous mosaic of... more
There exists little information on demographic responses of boreal songbirds to logging. We conducted a 4-yr (2003-2006) songbird mark-recapture study in western Newfoundland, where land cover is a naturally heterogeneous mosaic of productive spruce-fir forest, stunted taiga, and openings such as bogs, fens, and riparian zones. We compared apparent survival and rate of transience for adults of 14 species between
Research Interests:
New measurements of the molar volume and lattice parameter of Si, in near-perfect Si crystals, are reported and discussed. These measurements have been planned and performed within a worldwide collaboration coordinated by the CCM working... more
New measurements of the molar volume and lattice parameter of Si, in near-perfect Si crystals, are reported and discussed. These measurements have been planned and performed within a worldwide collaboration coordinated by the CCM working group on the Avogadro constant. The present determination of the molar volume, does confirm the value published previously within stated uncertainty.
Research Interests:
The determination of the Avogadro constant from two selected silicon crystals is described. The density, molar mass, and lattice spacing of the two crystals were measured at NMU, PTB, IRMM, IMGC, and NIST. When all the data are combined,... more
The determination of the Avogadro constant from two selected silicon crystals is described. The density, molar mass, and lattice spacing of the two crystals were measured at NMU, PTB, IRMM, IMGC, and NIST. When all the data are combined, it leads to the Avogadro constant of 6.022 1353 (21) times 1023 mol-1 with a relative combined standard uncertainty of 3.4
Abstract This paper describes an attempt to replace the present definition of the kilogram with the mass of a certain number of carbon atoms. This requires determination of the Avogadro constant, NA, with a relative uncertainty of 1 times... more
Abstract This paper describes an attempt to replace the present definition of the kilogram with the mass of a certain number of carbon atoms. This requires determination of the Avogadro constant, NA, with a relative uncertainty of 1 times 10-8. Silicon crystals are used in this determination. At present, a factor limiting factor is the measurement of the average molar mass of natural Si. Consequently, a worldwide collaboration has been set up, to produce, approximately, 5 kg of 28 Si single-crystal with an enrichment factor greater than ...
Research Interests:
... lon Proceeeea Determination of the isotopic composition and atomic weight of tungsten using gas source mass spectrometry: opening the route to the establishment of the traceability of tungsten amount measurements to the SI system? PDP... more
... lon Proceeeea Determination of the isotopic composition and atomic weight of tungsten using gas source mass spectrometry: opening the route to the establishment of the traceability of tungsten amount measurements to the SI system? PDP Taylor*, S. Valkiers, D. Vendelbo, P ...
Research Interests:
Thousands of oil and gas platforms are currently operating in offshore waters globally, and this industry is expected to expand in coming decades. Although the potential environmental impacts of offshore oil and gas activities are widely... more
Thousands of oil and gas platforms are currently operating in offshore waters globally, and this industry is expected to expand in coming decades. Although the potential environmental impacts of offshore oil and gas activities are widely recognized, there is limited understanding of their impacts on migratory and resident birds. A literature review identified 24 studies and reports of bird-platform interactions, most being qualitative and half having been peer-reviewed. The most frequently observed effect, for seabirds and landbirds, is attraction and sometimes collisions associated with lights and flares; episodic events have caused the deaths of hundreds or even thousands of birds. Though typically unpredictable, anecdotally, it is known that poor weather, such as fog, precipitation and low cloud cover, can exacerbate the effect of nocturnal attraction to lights, especially when coincidental with bird migrations. Other effects include provision of foraging and roosting opportuniti...
Research Interests:
Assistive technologies have recently emerged to improve the quality of life of severely disabled people by enhancing their independence in daily activities. Since many of those individuals have limited or non-existing control from the... more
Assistive technologies have recently emerged to improve the quality of life of severely disabled people by enhancing their independence in daily activities. Since many of those individuals have limited or non-existing control from the neck downward, alternative hands-free input modalities have become very important for these people to access assistive devices. In hands-free control, head movement has been proved to be a very effective user interface as it can provide a comfortable, reliable and natural way to access the device. Recently, neural networks have been shown to be useful not only for real-time pattern recognition but also for creating user-adaptive models. Since multi-layer perceptron neural networks trained using standard back-propagation may cause poor generalisation, the Bayesian technique has been proposed to improve the generalisation and robustness of these networks. This paper describes the use of Bayesian neural networks in developing a hands-free wheelchair contr...
Research Interests: Robotics, Algorithms, Artificial Intelligence, Pattern Recognition, Back Propagation, and 17 moreAssistive Technology, Quality of life, User Interface, Neural Network, Control system, Humans, Movement, Wheelchairs, Multi-layer Perceptron, Real Time, Computer User Interface Design, Head, Bayes Theorem, Equipment Design, Self-help devices, Man–machine Systems, and Assistive Device
Research Interests:
This reader-friendly introduction to the theory that underlies the many fascinating properties of solids assumes only an elementary knowledge of quantum mechanics. Taylor and Heinonen describe the methods for performing calculations and... more
This reader-friendly introduction to the theory that underlies the many fascinating properties of solids assumes only an elementary knowledge of quantum mechanics. Taylor and Heinonen describe the methods for performing calculations and making predictions of some of the many complex phenomena that occur in solids and quantum liquids. Their book, aimed at advanced undergraduates and beginning graduate students, leads the
Research Interests:
JOHN BOARDMAN et al., eds. The Cambridge Ancient History. Volume III, pt. 2: The Assyrian and Babylonian Empires and Other States of the Near East, from the Eighth to the Sixth Centuries BC. New York: Cambridge University Press, 1991. Pp.... more
JOHN BOARDMAN et al., eds. The Cambridge Ancient History. Volume III, pt. 2: The Assyrian and Babylonian Empires and Other States of the Near East, from the Eighth to the Sixth Centuries BC. New York: Cambridge University Press, 1991. Pp. xix, 906. $125.00 (us). Reviewed by William M. CalderH. T. WALLINGA. Ships and Sea-Power before the Great Persian War: The
Research Interests:
MICHAEL BENTLEY, ed. Companion to Historiography. London and New York: Roudedge, 1997. Pp. xvii,997. $150.00 (us). Reviewed by Simon HornblowerJEREMY BLACK. Maps and History: Constructing Images of the Past. New Haven and London: Yale... more
MICHAEL BENTLEY, ed. Companion to Historiography. London and New York: Roudedge, 1997. Pp. xvii,997. $150.00 (us). Reviewed by Simon HornblowerJEREMY BLACK. Maps and History: Constructing Images of the Past. New Haven and London: Yale University Press, 1997. Pp. 267. $35.00 (us). Reviewed by John A. AgnewGANG DENG. Chinese Maritime Activities and Socioeconomic Development, c. 2100 BC–1900AD. Westport: Greenwood Press, 1997.
Research Interests:
... Click on any of the links below to perform a new search. ERIC #: EJ501044. Title: Our "Adventure of Experiencing": Reflective Practice and Drama Research. Authors: Taylor, Philip M. Descriptors: Action Research; Classroom ...
Research Interests:
... Serendipity Theatre; Secretary: Gretta Berghammer, University of Northern Iowa; Treasurer: Candace Sorenson, Spirit in the Square Center for the Arts; Past President: Kim Wheetley, Southeast Institute for Education in Theatre; Network... more
... Serendipity Theatre; Secretary: Gretta Berghammer, University of Northern Iowa; Treasurer: Candace Sorenson, Spirit in the Square Center for the Arts; Past President: Kim Wheetley, Southeast Institute for Education in Theatre; Network Council Chair: Sue Wurster, The Calhoun ...
Research Interests:
Research Interests:
The Water Framework Directive (WFD) 2000/60/EC [1] is the legislative framework for protecting the quality of inland and coastal waters in the European Union (EU). It defines chemical substances for priority remediation in the daughter... more
The Water Framework Directive (WFD) 2000/60/EC [1] is the legislative framework for protecting the quality of inland and coastal waters in the European Union (EU). It defines chemical substances for priority remediation in the daughter Decision 2455/2001/EC [2] and their maximum ...