bluuebunny/crossref_metadata_2025 huggingface dataset:
Land use and income diversification: comparing traditional and colonist populations in the Brazilian Amazon
Authors: Caviglia‐Harris Jill L. , Sills Erin O.
Published: April 2005

This article compares and analyzes land use and income diversification among two distinct groups of farmers in the Brazilian Amazon: recent colonists in Ouro Preto do Oeste, Rondônia, and traditional long‐term residents along the Tapajós River, Pará. We investigate the hypothesis that farmers who diversify their cash income sources clear less forest on an annual basis, and we compare these livelihood choices across colonist and traditional populations. In particular, we develop a conceptual model based on the household production framework and use econometric models to identify determinants of diversification and forest clearing. We find that diversification of agricultural cash crops is negatively correlated with forest clearing by colonists, providing limited evidence for the hypothesis. Other significant covariates of diversification and forest clearing include cash income levels, stage in family life cycle, cattle ownership, and chemical inputs. Differences in these variables, and differences in household response to these variables, explain variation in diversification and forest clearing across the two populations.
In vivo and in vitro functional characterization of Andersen's syndrome mutations
Authors: Bendahhou Saïd , Fournier Emmanuel , Sternberg Damien , Bassez Guillaume , Furby Alain , Sereni Carole , Donaldson Matthew R. , Larroque Marie‐Madeleine , Fontaine Bertrand , Barhanin Jacques
Published: April 2005

The inward rectifier K+ channel Kir2.1 carries all Andersen's syndrome mutations identified to date. Patients exhibit symptoms of periodic paralysis, cardiac dysrhythmia and multiple dysmorphic features. Here, we report the clinical manifestations found in three families with Andersen's syndrome. Molecular genetics analysis identified two novel missense mutations in the KCNJ2 gene leading to amino acid changes C154F and T309I of the Kir2.1 open reading frame. Patch clamp experiments showed that the two mutations produced a loss of channel function. When co‐expressed with Kir2.1 wild‐type (WT) channels, both mutations exerted a dominant‐negative effect leading to a loss of the inward rectifying K+ current. Confocal microscopy imaging in HEK293 cells is consistent with a co‐assembly of the EGFP‐fused mutant proteins with WT channels and proper traffick to the plasma membrane to produce silent channels alone or as hetero‐tetramers with WT. Functional expression in C2C12 muscle cell line of newly as well as previously reported Andersen's syndrome mutations confirmed that these mutations act through a dominant‐negative effect by altering channel gating or trafficking. Finally, in vivo electromyographic evaluation showed a decrease in muscle excitability in Andersen's syndrome patients. We hypothesize that Andersen's syndrome‐associated mutations and hypokalaemic periodic paralysis‐associated calcium channel mutations may lead to muscle membrane hypoexcitability via a common mechanism.
Transient outward potassium current, ‘Ito’, phenotypes in the mammalian left ventricle: underlying molecular, cellular and biophysical mechanisms
Authors: Patel Sangita P. , Campbell Donald L.
Published: April 2005

At least two functionally distinct transient outward K+ current (Ito) phenotypes can exist across the free wall of the left ventricle (LV). Based upon their voltage‐dependent kinetics of recovery from inactivation, these two phenotypes are designated ‘Ito,fast’ (recovery time constants on the order of tens of milliseconds) and ‘Ito,slow’ (recovery time constants on the order of thousands of milliseconds). Depending upon species, either Ito,fast, Ito,slow or both current phenotypes may be expressed in the LV free wall. The expression gradients of these two Ito phenotypes across the LV free wall are typically heterogeneous and, depending upon species, may consist of functional phenotypic gradients of both Ito,fast and Ito,slow and/or density gradients of either phenotype. We review the present evidence (molecular, biophysical, electrophysiological and pharmacological) for Kv4.2/4.3 α subunits underlying LV Ito,fast and Kv1.4 α subunits underlying LV Ito,slow and speculate upon the potential roles of each of these currents in determining frequency‐dependent action potential characteristics of LV subepicardial versus subendocardial myocytes in different species. We also review the possible functional implications of (i) ancillary subunits that regulate Kv1.4 and Kv4.2/4.3 (Kvβ subunits, DPPs), (ii) KChIP2 isoforms, (iii) spider toxin‐mediated block of Kv4.2/4.3 (Heteropoda toxins, phrixotoxins), and (iv) potential mechanisms of modulation of Ito,fast and Ito,slow by cellular redox state, [Ca2+]i and kinase‐mediated phosphorylation. Ito phenotypic activation and state‐dependent gating models and molecular structure–function relationships are also discussed.
Diagnosis for Loose Blades in Gas Turbines Using Wavelet Analysis
Authors: Lim Meng Hee , Leong M. Salman
Published: April 2005

The application of wavelet analysis to diagnose loose blades condition in gas turbines is examined in this paper. Experimental studies were undertaken to simulate loose blades condition occurring in gas turbines in an attempt to understand vibration response associated with loose blades under different operating conditions. Results showed that loose blades were undetectable under steady state operating condition. During turbine coast down, a loose blade could be detected based on the impactic signals induced by the loose blades on the rotor and thus excited the natural frequencies of the rotor assembly. Results from the coast down condition showed that wavelet analysis was more sensitive and effective than Fourier analysis for loose blade diagnosis. The severity, the number, and the configuration of the loose blades could be potentially estimated based on the pattern of the coast down wavelet map.
Heat Transfer Measurements Using Liquid Crystals in a Preswirl Rotating-Disk System
Authors: Lock Gary D. , Yan Youyou , Newton Paul J. , Wilson Michael , Owen J. Michael
Published: April 2005

Preswirl nozzles are often used in gas turbines to deliver the cooling air to the turbine blades through receiver holes in a rotating disk. The distribution of the local Nusselt number, Nu, on the rotating disk is governed by three nondimensional fluid-dynamic parameters: preswirl ratio, βp, rotational Reynolds number, Reϕ, and turbulent flow parameter, λT. A scaled model of a gas turbine rotor–stator cavity, based on the geometry of current engine designs, has been used to create appropriate flow conditions. This paper describes how a thermochromic liquid crystal, in conjunction with a stroboscopic light and digital camera, is used in a transient experiment to obtain contour maps of Nu on the rotating disk. The thermal boundary conditions for the transient technique are such that an exponential-series solution to Fourier’s one-dimensional conduction equation is necessary. A method to assess the uncertainty in the measurements is discussed and these uncertainties are quantified. The experiments reveal that Nu on the rotating disk is axisymmetric except in the region of the receiver holes, where significant two-dimensional variations have been measured. At the higher coolant flow rates studied, there is a peak in heat transfer at the radius of the preswirl nozzles. The heat transfer is governed by two flow regimes: one dominated by inertial effects associated with the impinging jets from the preswirl nozzles, and another dominated by viscous effects at lower flow rates. The Nusselt number is observed to increase as either Reϕ or λT increases.
Feasibility Analysis for the Rotordynamic Performance of API617
Authors: Ahn Hyeong-Joon , Maslen Eric H. , Iwasaki Tetsuya
Published: April 2005

The rotordynamic performance of API 617 standards provides two primary requirements. First, the standard stipulates system damping near the expected operating speed range. Second, the standard requires a specific bound of the worst case unbalance response. The problem this poses for machine designers is (1) feasibility: can bearings be designed for a given rotor to meet API 617 and (2) if so, how can these bearings be designed? Our primary effort in this research is to convert the API requirements to a control design objective for a bearing. This permits direct assessment of the feasible design problem as well as providing a means to synthesize optimal bearing dynamics. In addition to providing synthesis of magnetic bearings, the resulting bearing transfer functions give direct guidance to selection of more conventional fluid film or rolling element bearings.
Experimental Investigation of the Interaction of Unsteady Flow With Combustion
Authors: Schildmacher K.-U. , Koch R.
Published: April 2005

In order to reduce the dimensions of the combustor, swirl stabilized flames are used in heavy duty gas turbines. In our recent investigation of the swirling flow at a single heavy duty gas turbine burner under nonreacting conditions typical instabilities like precessing vortex cores and vortex shedding have been found (Schildmacher et al., Proceedings of the 6th European Conference on Industrial Furnaces and Boilers). In the present paper the experimental investigations will be discussed. Combustion instabilities have been analyzed by phase-locked laser doppler anemometer measurements. For the reacting flow, also combustion instabilities could be detected. The amplitude increases strongly with the equivalence ratio. The frequency of the oscillations for reacting conditions has been found to be slightly shifted towards lower frequencies compared to those of the corresponding nonreacting flow. In addition, for the reacting flow a linear and nonlinear range of oscillations could be discriminated.
Crack Detection in a Rotor Dynamic System by Vibration Monitoring—Part I: Analysis
Authors: Green Itzhak , Casey Cody
Published: April 2005

Many practical rotor dynamic systems contain shaft/rotor elements that are highly susceptible to transverse cross-sectional cracks due to fatigue. The early detection of mechanical malfunction that can be provided by an effective vibration monitoring system is essential. Two theoretical analyses, global and local asymmetry crack models, are utilized to identify characteristics of the system response that may be directly attributed to the presence of a transverse crack in a rotating shaft. A model consisting of an overhung whirling rotor is utilized to match an experimental test rig. A 2X harmonic component of the system response is shown to be the primary response characteristic resulting from the introduction of a crack. Once the unique characteristics of the system response are identified, they serve then as target observations for the monitoring system.
Forced Low-Frequency Spray Characteristics of a Generic Airblast Swirl Diffusion Burner
Authors: Eckstein J. , Freitag E. , Hirsch C. , Sattelmayer T. , von der Bank R. , Schilling T.
Published: April 2005

The low-frequency response of the spray from a generic airblast diffusion burner with a design typical of an engine system has been investigated as part of an experimental study to describe the combustion oscillations of aeroengine combustors called rumble. The atomization process was separated from the complex instability mechanism of rumble by using sinusoidal forcing of the air mass flow rate without combustion. Pressure drop across the burner and the velocity on the burner exit were found to follow the steady Bernoulli equation. Phase-locked particle image velocimetry measurements of the forced velocity field of the burner show quasisteady behavior of the air flow field. The phase-locked spray characteristics were measured for different fuel flow rates. Here again quasi-steady behavior of the atomization process was observed. With combustion, the phase-locked Mie-scattering intensity of the spray cone was found to follow the spray behavior measured in the noncombusting tests. These findings lead to the conclusion that the unsteady droplet Sauter mean diameter mean and amplitude of the airblast atomizer can be calculated using the steady-state atomization correlations with the unsteady burner air velocity.
Conceptual Design and Cooling Blade Development of 1700°C Class High-Temperature Gas Turbine
Authors: Ito Shoko , Saeki Hiroshi , Inomata Asako , Ootomo Fumio , Yamashita Katsuya , Fukuyama Yoshitaka , Koda Elichi , Takehashi Toru , Sato Mikio , Koyama Miki , Ninomiya Toru
Published: April 2005

In this paper we describe the conceptual design and cooling blade development of a 1700°C-class high-temperature gas turbine in the ACRO-GT-2000 (Advanced Carbon Dioxide Recovery System of Closed-Cycle Gas Turbine Aiming 2000 K) project. In the ACRO-GT closed cycle power plant system, the thermal efficiency aimed at is more than 60% of the higher heating value of fuel (HHV). Because of the high thermal efficiency requirement, the 1700°C-class high-temperature gas turbine must be designed with the minimum amount of cooling and seal steam consumption. The hybrid cooling scheme, which is a combination of closed loop internal cooling and film ejection cooling, was chosen from among several cooling schemes. The elemental experiments and numerical studies, such as those on blade surface heat transfer, internal cooling channel heat transfer, and pressure loss and rotor coolant passage distribution flow phenomena, were conducted and the results were applied to the conceptual design advancement. As a result, the cooling steam consumption in the first stage nozzle and blade was reduced by about 40% compared with the previous design that was performed in the WE-NET (World Energy Network) Phase-I.
The Use of Helmholtz Resonators in a Practical Combustor
Authors: Dupe`re Iain D. J. , Dowling Ann P.
Published: April 2005

The drive to reduce emissions has led to the development of lean premixed combustors. However, lean premixed combustion is often associated with combustion oscillations which can be so severe that they can cause structural damage to the engine. Since the associated frequencies are typically of the order of hundreds of Hertz, there is a need for a compact device to absorb the noise which drives the oscillation. Helmholtz resonators are commonly used as absorbers of incident acoustic power. In addition they are relatively compact. However, their use in combustors creates practical issues, such as placement within the chamber, neck length, and cooling, which need to be addressed. In this paper we consider these practical problems and describe how to overcome them in a real combustor.
High Temperature Characterization of a Radial Magnetic Bearing for Turbomachinery
Authors: Provenza Andrew J. , Montague Gerald T. , Jansen Mark J. , Palazzolo Alan B. , Jansen Ralph H.
Published: April 2005

Open loop, experimental force and power measurements of a radial, redundant-axis, magnetic bearing at temperatures to 1000°F (538°C) and rotor speeds to 15,000 rpm along with theoretical temperature and force models are presented in this paper. The experimentally measured force produced by a single C-core circuit using 22A was 600 lb (2.67 kN) at room temperature and 380 lb (1.69 kN) at 538°C. These values were compared with force predictions based on a one-dimensional magnetic circuit analysis and a thermal analysis of gap growth as a function of temperature. The analysis showed that the reduction of force at high temperature is mostly due to an increase in radial gap due to test conditions, rather than to reduced core permeability. Tests under rotating conditions showed that rotor speed has a negligible effect on the bearing’s static force capacity. One C-core required approximately 340 W of power to generate 190 lb (845 N) of magnetic force at 538°C, however the magnetic air gap was much larger than at room temperature. The data presented are after bearing operation for eleven total hours at 538°C and six thermal cycles.
Measurement of Smoke Particle Size and Distribution Within a Gas Turbine Combustor
Authors: Brundish K. D. , Miller M. N. , Wilson C. W. , Jefferies M. , Hilton M. , Johnson M. P.
Published: April 2005

The objective of the work described in this paper was to identify a method of making measurements of the smoke particle size distribution within the sector of a gas turbine combustor, using a scanning mobility particle sizing (SMPS) analyzer. As well as gaining a better understanding of the combustion process, the principal reasons for gathering these data was so that they could be used as validation for computational fluid dynamic and chemical kinetic models. Smoke mass and gaseous emission measurements were also made simultaneously. A “water cooled,” gas sampling probe was utilized to perform the measurements at realistic operating conditions within a generic gas turbine combustor sector. Such measurements had not been previously performed and consequently initial work was undertaken to gain confidence in the experimental configuration. During this investigation, a limited amount of data were acquired from three axial planes within the combustor. The total number of test points measured were 45. Plots of the data are presented in two-dimensional contour format at specific axial locations in addition to axial plots to show trends from the primary zone to the exit of the combustor. Contour plots of smoke particle size show that regions of high smoke number concentration once formed in zones close to the fuel injector persist in a similar spatial location further downstream. Axial trends indicate that the average smoke particle size and number concentration diminishes as a function of distance from the fuel injector. From a technical perspective, the analytical techniques used proved to be robust. As expected, making measurements close to the fuel injector proved to be difficult. This was because the quantity of smoke in the region was greater than 1000mg/m3. It was found necessary to dilute the sample prior to the determination of the particle number concentration using SMPS. The issues associated with SMPS dilution are discussed.
Adaptive Myriad Filter for Improved Gas Turbine Condition Monitoring Using Transient Data
Authors: Surender Vellore P. , Ganguli Ranjan
Published: April 2005

The removal of noise and outliers from measurement signals is a major problem in jet engine health monitoring. In this study, we look at the myriad filter as a substitute for the moving average filter that is widely used in the gas turbine industry. The three ideal test signals used in this study are the step signal that simulates a single fault in the gas turbine, while ramp and quadratic signals simulate long term deterioration. Results show that the myriad filter performs better in noise reduction and outlier removal when compared to the moving average filter. Further, an adaptive weighted myriad filter algorithm that adapts to the quality of incoming data is studied. The filters are demonstrated on simulated clean and deteriorated engine data obtained from an acceleration process from idle to maximum thrust condition. This data was obtained from published literature and was simulated using a transient performance prediction code. The deteriorated engine had single component faults in the low pressure turbine and intermediate pressure compressor. The signals are obtained from T2 (IPC total outlet temperature) and T6 (LPT total outlet temperature) engine sensors with their nonrepeatability values that were used as noise levels. The weighted myriad filter shows even greater noise reduction and outlier removal when compared to the sample myriad and a FIR filter in the gas turbine diagnosis. Adaptive filters such as those considered in this study are also useful for online health monitoring, as they can adapt to changes in quality of incoming data.
Copper diffusion barrier properties of CVD boron carbo-nitride
Authors: Engbrecht E. R. , Sun Y.-M. , Junker K. H. , White J. M. , Ekerdt J. G.
Published: April 2005

The copper diffusion barrier properties of amorphous boron carbo-nitride (BCxNy) films were studied. The BCxNy films were deposited by chemical vapor deposition at 360°C and 1Torr using dimethylamine borane with no reaction gas (BC0.37N0.15), with NH3(BC0.19N0.44), or with C2H4(BC0.90N0.08); their dielectric constants were 4.1, 4.4, and 3.9, respectively. A SiC0.76N0.44 film was used to benchmark the study. Barrier films were deposited on 7nm thermal oxide∕n-type Si substrates. The leakage current for BC0.90N0.08, 1.1×10−8A∕cm2 at 0.5MV∕cm, is the lowest of the three but it is larger than that of the benchmark SiC0.76N0.44 film, 5.5×10−9A∕cm2. Time dependent dielectric breakdown is used to test barrier time-to-failure of Cu-gate capacitors at 150°C and +2to5MV∕cm. BC0.90N0.80 displayed barrier performance comparable to SiC0.76N0.44 and was noticeably better than BC0.37N0.15 and BC0.19N0.44. Overall, BCxNy barriers are promising and are improved with lower boron content, fewer B–B bonds, and increased B–C bonds.
Effects of Pd activation on the self annealing of electroless copper deposition using Co(II)–ethylenediamine as a reducing agent
Authors: Lee Chang Hwa , Kim Jae Jeong
Published: April 2005

We investigated the effect of Pd activation on self-annealing in electroless Cu deposits using Co(II)–ethylenediamine as a reducing agent. The size and population of Pd particles were controlled by Pd ion concentration and activation time, which resulted in changes in the sheet resistances. While the low population of Pd particles (<109cm−2) was unable to create completely continuous Cu film in subsequent electroless deposition and induced high film resistivity due to the voids, Pd particles that were over 20nm in diameter increased the resistivity by raising the surface roughness of the Cu film. The optimal Pd activation condition was with Pd particle density of 1.73×109cm−2 with 14nm diameters. The resistivity of the Cu film in the optimal activation condition decreased to 2.46μΩcm. The deposited Cu film showed a low resistivity and a strong Cu (111) texture with the decrease in size and increase in the number of the Pd particles.
Fabrication of 5nm gap pillar electrodes by electron-beam Pt deposition
Authors: Gazzadi Gian Carlo , Frabboni Stefano
Published: April 2005

Using a focused ion beam (FIB)-scanning electron microscope (SEM) workstation, free-standing nanoelectrodes were grown by SEM-assisted Pt deposition between FIB-patterned Au pads. Two pillar electrodes were first grown with opposite-tilted geometries up to a spacing of 120nm. By SEM scanning over the pillar tips, under a precursor gas flow, gap reduction down to 5nm was monitored in live imaging mode. As shown by transmission electron microscopy (TEM) analysis, the deposit consisted of Pt crystallites embedded in amorphous C. Local annealing by high-current TEM irradiation increased the size of the Pt grains, which produced clear diffraction rings. The annealing procedure did not affect the overall shape of the tips, indicating good mechanical stability of the pillars. We show how this FIB-SEM approach is suitable to fabricate multielectrode nanostructures by depositing a third pillar electrode below the gap of the tilted electrodes.
Investigation of a microtriode with a planar field emitter-extractor source fabricated by direct-write nanolithography using electron beam induced deposition
Authors: Sellmair Josef , Edinger Klaus , Koops Hans W. P.
Published: April 2005

A simple microtriode with planar field emission cathode is investigated. Electron optical performance and field distribution are simulated using numerical electron optics. A field emitter tip is fabricated by direct write nanolithography with electron beam induced deposition. The emission properties are studied in UHV and high vacuum. Measurements of currents from deposited emitters are recorded with milli-second resolution to monitor short-term variations in long-term measurements. Emission currents of a few nanoamperes are observed over several days without and with the use of an ion mirror. Depending on vacuum conditions the currents show a characteristic variation of up to 50%. The work is aimed to develop a planar micro-triode with very high current-carrying capability and low transconductance.
Investigation of a nanocrystalline silicon phase embedded in SiOx thin films grown by pulsed laser deposition
Authors: Fazio Enza , Barletta Enrico , Barreca Francesco , Neri Fortunato , Trusso Sebastiano
Published: April 2005

The formation of nanocrystalline silicon clusters in SiOx thin films has been investigated by means of micro-Raman and Fourier transform infrared spectroscopic techniques. The samples were deposited, by means of pulsed laser ablation of a silicon target in a controlled oxygen gas environment, on substrates heated up to 883 K. Experimental results show that, by appropriately varying the deposition parameters, it is possible to achieve a fully coordinated silicon dioxide phase with the contemporary development of a nanometer-sized crystalline silicon phase and/or an amorphous one. Comparison between the effect of a relatively high substrate temperature and of a post-deposition annealing treatment have been exploited. From the line-shape analysis of the silicon TO vibrational mode Raman band, crystalline silicon volume fractions up to 90% have been estimated, while the nanocrystalline cluster sizes remained almost constant around 3.5 nm. A good agreement between our results and the predictions of silicon nanoclusters formation by a silicon atom diffusion-controlled mechanism has been found.
The Ping-Pong Cannon: A Closer Look
Authors: Peterson Richard W. , Pulford Benjamin N. , Stein Keith R.
Published: April 2005

This paper describes the use of laser pulse photography, optical timing, and pulsed Schlieren to look more closely at the dynamics of a popular lecture demonstration—the so-called “Ping-Pong cannon” or “vacuum bazooka.”1,2 These optical diagnostic techniques are applied to two types of cannons and lead to greater knowledge of the kinematics of the accelerating ball, along with some details of the exit mechanism and subsequent target interactions.
Of Orbits, Conics, and Grammar
Authors: Henderson Hugh
Published: April 2005

In the half-dozen or so years leading up to the publication of the Principia, Isaac Newton observed the comets of 1680 and 1682 and wrestled with the extent to which his law of gravitation could be applied. In time, he would see the connections between the four possible orbits of a satellite (circular, elliptical, parabolic, and hyperbolic) and the four curves produced by the careful carving of a cone. But if we look a little further into the conic sections, we find some interesting connections among the natural orbit of a satellite, ancient mathematics, and the roots of familiar words. Illuminating these connections for introductory physics students may help them to better understand the role of language and mathematics in the descriptions of science.
Curriculum Reform and Professional Development in San Diego City Schools
Authors: Taylor Joseph A. , Powell Janet Carlson , Van Dusen David R. , Schindler Bonnie J. , Pearson Bill , Lavine Dan , Bess Kim
Published: April 2005

In the spring of 2001, the San Diego City Schools (SDCS) initiated a science reform program that involved several significant changes. The first was to resequence the science courses to have students take physics first (in ninth grade), followed by chemistry, then biology. Second was a change in the students' high school graduation requirement to specifically name physics, chemistry, and biology as being required. Physics is now required for all freshmen in 18 SDCS high schools. These new regulations align with the University of California's recommendation of three years of laboratory science for freshman admission. To accommodate the dramatic increase in physics enrollment that resulted from these changes, SDCS needed to augment its existing physics faculty. The only option was to ask approximately 40 “out-of-discipline” (credentialed in science but not in physics) teachers from the district to teach ninth-grade physics.
An Observation of PKJKP: Inferences on Inner Core Shear Properties
Authors: Cao Aimin , Romanowicz Barbara , Takeuchi Nozomu
Published: April 2005

The seismic phase PKJKP, which traverses the inner core as a shear wave and would provide direct evidence for its solidity, has been difficult to detect. Using stacked broadband records from the Gräfenberg array in Germany, we documented a high signal-to-noise phase, the arrival time and slowness of which agree with theoretical predictions for PKJKP. The back azimuth of this arrival is also consistent with predictions for PKJKP, as is the comparison with a pseudoliquid inner core model. Envelope modeling of the PKJKP waveform implies a shear velocity gradient with depth in the inner core that is slightly larger than that in the preliminary reference Earth model.
Resting Microglial Cells Are Highly Dynamic Surveillants of Brain Parenchyma in Vivo
Authors: Nimmerjahn Axel , Kirchhoff Frank , Helmchen Fritjof
Published: April 2005

Microglial cells represent the immune system of the mammalian brain and therefore are critically involved in various injuries and diseases. Little is known about their role in the healthy brain and their immediate reaction to brain damage. By using in vivo two-photon imaging in neocortex, we found that microglial cells are highly active in their presumed resting state, continually surveying their microenvironment with extremely motile processes and protrusions. Furthermore, blood-brain barrier disruption provoked immediate and focal activation of microglia, switching their behavior from patroling to shielding of the injured site. Microglia thus are busy and vigilant housekeepers in the adult brain.
Role of HtrA in Growth and Competence of
Streptococcus mutans
UA159
Authors: Ahn Sang-Joon , Lemos José A. C. , Burne Robert A.
Published: April 2005

We report here that HtrA plays a role in controlling growth and competence development for genetic transformation in
Streptococcus mutans
. Disruption of the gene for HtrA resulted in slow growth at 37°C, reduced thermal tolerance at 42°C, and altered sucrose-dependent biofilm formation on polystyrene surfaces. The
htrA
mutant also displayed a significantly reduced ability to undergo genetic transformation. A direct association between HtrA and genetic competence was demonstrated by the increased expression of the
htrA
gene upon exposure to competence-stimulating peptide. The induction of
htrA
gradually reached a maximum at around 20 min, suggesting that HtrA may be involved in a late competence response. Complementation of the
htrA
mutation in a single copy on the chromosome of the mutant could rescue the defective growth phenotypes but not transformability, apparently because a second gene,
spo0J
, immediately downstream of
htrA
, also affects transformation. The
htrA
and
spo0J
genes were shown to be both individually transcribed and cotranscribed and probably have a functional connection in competence development. HtrA regulation appears to be finely tuned in
S. mutans
, since strains containing multiple copies of
htrA
exhibited abnormal growth phenotypes. Collectively, the results reveal HtrA to be an integral component of the regulatory network connecting cellular growth, stress tolerance, biofilm formation, and competence development and reveal a novel role for the
spo0J
gene in genetic transformation.
Eocene paleo-physiography and drainage directions, southern Interior Plateau, British Columbia
Authors: Tribe Selina
Published: April 2005

A map of reconstructed Eocene physiography and drainage directions is presented for the southern Interior Plateau region, British Columbia south of 53°N. Eocene landforms are inferred from the distribution and depositional paleoenvironment of Eocene rocks and from crosscutting relationships between regional-scale geomorphology and bedrock geology of known age. Eocene drainage directions are inferred from physiography, relief, and base level elevations of the sub-Eocene unconformity and the documented distribution, provenance, and paleocurrents of early Cenozoic fluvial sediments. The Eocene landscape of the southern Interior Plateau resembled its modern counterpart, with highlands, plains, and deeply incised drainages, except regional drainage was to the north. An anabranching valley system trending west and northwest from Quesnel and Shuswap Highlands, across the Cariboo Plateau to the Fraser River valley, contained north-flowing streams from Eocene to early Quaternary time. Other valleys dating back at least to Middle Eocene time include the North Thompson valley south of Clearwater, Thompson valley from Kamloops to Spences Bridge, the valley containing Nicola Lake, Bridge River valley, and Okanagan Lake valley. During the early Cenozoic, highlands existed where the Coast Mountains are today. Southward drainage along the modern Fraser, Chilcotin, and Thompson River valleys was established after the Late Miocene.
The McAbee flora of British Columbia and its relation to the Early-Middle Eocene Okanagan Highlands flora of the Pacific Northwest
Authors: Dillhoff Richard M , Leopold Estella B , Manchester Steven R
Published: April 2005

Megafossils and pollen data are used to compare the flora found at the McAbee site, located near the town of Cache Creek, British Columbia, to six other well-collected Eocene lacustrine floras of Washington and western British Columbia. A diverse flora is found at McAbee consisting of at least 87 taxa. Gymnosperms are common, including sixteen separate species, 14 conifers and two ginkgos. A minimum of 67 angiosperm genera are represented in the flora, many yet to be described. The dominant dicotyledonous elements of the leaf assemblage at McAbee include Fagus (also represented by nuts and cupules) with Ulmus and representatives of the Betulaceae, especially Betula and Alnus. The confirmation of Fagus, also rarely found from sites at Princeton, British Columbia, and Republic, Washington, provides the oldest well-documented occurrence of the genus, predating the Early Oligocene records of Fagus previously reported for North America, Asia, and Europe. Data provided by pollen analysis broadens our knowledge of the McAbee flora. Angiosperm pollen typically predominates over gymnosperms with the Ulmoideae and Betulaceae being the most common angiosperm pollen types. Members of the Pinaceae dominate the gymnosperm pollen record. Paleoclimatic estimates for McAbee are slightly cooler than for the Republic and Princeton localities and thermophilic elements, such as Sabal found at Princeton or Ensete and Zamiaceae found at Republic are not known from McAbee.
Fossil biotas from the Okanagan Highlands, southern British Columbia and northeastern Washington State: climates and ecosystems across an Eocene landscape
Authors: Greenwood David R , Archibald S Bruce , Mathewes Rolf W , Moss Patrick T
Published: April 2005

The late Early to early Middle Eocene Okanagan Highlands fossil sites, spanning ~1000 km northsouth (northeastern Washington State, southern British Columbia) provide an opportunity to reconstruct biotic communities across a broad upland landscape during the warmest part of the Cenozoic. Plant taxa from these fossil sites are characteristic of the modern eastern North American deciduous forest zone, principally the mixed mesophytic forest, but also include extinct taxa, taxa known only from eastern Asian mesothermal forests, and a small number of taxa restricted to the present-day North American west coast coniferous biome. In this preliminary report, paleoclimates and forest types are reconstructed using collections from Republic in Washington State, USA., and Princeton, Quilchena, Falkland, McAbee, Hat Creek, Horsefly, and Driftwood Canyon in British Columbia, Canada. Both leaf margin analysis (LMA) and quantitative bioclimatic analysis of identified nearest living relatives of megaflora indicated upper microthermal to lower mesothermal moist environments (MAT ~1015 °C, CMMT > 0 °C, MAP > 100 cm/year). Some taxa common to most sites suggest cool conditions (e.g., Abies, other Pinaceae; Alnus, other Betulaceae). However, all floras contain a substantive broadleaf deciduous element (e.g., Fagaceae, Juglandaceae) and conifers (e.g., Metasequoia) with the bioclimatic analysis yielding slightly higher MAT than LMA. Thermophilic (principally mesothermal) taxa include various insects, the aquatic fern Azolla, palms, the banana relative Ensete, taxodiaceous conifers, Eucommia and Gordonia, taxa which may have occurred near their climatic limits. The mixture of thermophilic and temperate insect and plant taxa indicates low-temperature seasonality (i.e., highly equable climate).
Taphonomic variations in Eocene fish-bearing varves at Horsefly, British Columbia, reveal 10 000 years of environmental change
Authors: Barton Douglas G , Wilson Mark VH
Published: April 2005

The Eocene Horsefly locality in British Columbia has yielded many fossil fishes, insects, and plants. Its varved sediments make it ideal for study of temporal changes in environment and fish morphology. Several intervals of diatomaceous varves indicate a deep, stratified lake setting. Earlier studies focused on morphological and taphonomic change during the 700-year H2 interval and morphological change during the 10 000-year H3 interval. The present study uses taphonomy as an index for environmental change during the ten millennia represented by H3, comparing taphonomic changes with the morphologic changes found earlier. The H3 interval records deposition in deep water, indicated by dominance of the fish genera Amyzon and Eohiodon. Quiet water conditions are indicated by minimal fin disarticulation. Hypoxia at the time of fish death is confirmed by open mouths of most fish specimens, while cool water on the lake floor prevented full flotation of fish carcasses. Water depth, temperature, and oxygenation fluctuated during H3 deposition. Periods of cooler, deeper, more hypoxic water are indicated by greater numbers and size of Amyzon specimens and by less disarticulation of skull and abdominal bones. Periods of warmer, shallower, more oxygenated waters are indicated by more disarticulation, less fin tetany, smaller fish specimens, and greater diversity of species. Correlations between the taphonomic changes and morphological changes in A. aggregatum are weak. Therefore, the morphological changes are not easily explained as ecophenotypic or short-term evolutionary responses to changes in physical lake conditions.
The effect of time and site on incidence and spread of pruning-related decay in plantation-grown Eucalyptus nitens
Authors: Barry Karen M , Hall Malcolm F , Mohammed Caroline L
Published: April 2005

Quantitative information on stem decay in eucalypt plantations grown for solid wood products, with consideration of the effect of site, pruning, and spread of decay with time, is required for the prediction of harvest yield and quality. A trial at three Eucalyptus nitens (Dean & Maiden) Maiden plantations in Tasmania revealed that the effect of time on the number and size of decay columns was substantially greater than the effect of site or of whether trees were pruned or not. Length of decay columns was 3.4-fold greater on average for the trees assessed 5.5 years after pruning than at 1 year. All decay columns in pruned trees were restricted to the knotty core, and the amount of decay-free clearwood increased over time. A controlled wounding trial showed that decay in sapwood was not significantly different in length with site but was mainly determined by the fungal species used. Ongoing research to monitor the spread of decay in pruned plantation-grown E. nitens will be important to enable prediction of the future impact of decay on harvest yields of solid wood products.
An assessment of phosphorus limitations to soil nitrogen availability across forest ecosystems of north coastal British Columbia
Authors: Kranabetter J M , Banner A , Groot A de
Published: April 2005

The wet, slow-growing forests of western redcedar (Thuja plicata Donn ex D. Don) and salal (Gaultheria shallon Pursh) on the north coast of British Columbia are characteristically low in available phosphorus (P) compared with more productive forest ecosystems. It has been suggested that declining P availability can eventually limit soil biological activity and restrict nitrogen (N) cycling. We investigated this potential link between P availability and N cycling for three forest types (cedarsalal, hemlock  lanky moss and spruce  sword fern) covering a wide gradient in site productivity. Forest floors (upper 20 cm) and mineral soils (20 cm depth) were collected from five replicate sites of each forest type and incubated for 20 weeks at field moisture content with and without an amendment of NaH2PO4. We found that organic P concentrations of both forest floors and mineral soils were positively correlated to extractable inorganic N concentrations (unamended soils over 20 weeks). The addition of P to the low-productivity cedarsalal soils led to significant increases in extractable inorganic N in the forest floors and mineral soils. P amendments led to either a smaller or nonsignificant increase in extractable N for moderately and highly productive soils. Soil respiration of CO2 and respiration quotients were substantially reduced in forest floors with a P amendment, suggesting N mineralization was governed by exoenzyme allocation rather than decomposition rates. These results demonstrate a possible enhancement in N supplies with an application of P to low-productivity cedarsalal forests.
Comparison of four measures designed for assessing the fit between the demand and output distributions of logs
Authors: Kivinen Veli-Pekka , Uusitalo Jori , Nummi Tapio
Published: April 2005

In recent years, as customer-oriented production strategies have gained ground, especially in the sawmill industry, the fit between the demand and the actual output for logs of different sizes and qualities has become an important criterion for evaluating bucking outcomes. In this paper, we present four measures for determining the similarity between the demand and output log distributions: (1) the apportionment degree, (2) the χ2 statistic, (3) Laspeyres' quantity index, and (4) the price-weighted apportionment degree. The potential of each measure for determining similarity was analyzed in two ways. (1) In an experiment involving 10 artificial Norway spruce (Picea abies (L.) Karst.) stands and two demand matrices for spruce logs, each study stand was harvested using a bucking simulator and the resulting log distributions were then compared with the desired distribution in each of the four measures. (2) The advantages and disadvantages of the measures were analyzed in relation to the requirements for an ideal goodness-of-fit measure. Both analyses suggested that not one of the four measures tested is superior, but that all can be used in actual wood procurement.
Interactive effects of tree and herb cover on survivorship, physiology, and microclimate of conifer seedlings at the alpine tree-line ecotone
Authors: Maher Eliza L , Germino Matthew J , Hasselquist Niles J
Published: April 2005

Factors affecting the establishment of trees in subalpine meadows are important to population dynamics of trees in the alpine tree-line ecotone (ATE). Interactive effects of tree and herb cover on conifer seedlings were investigated in the ATE of the Snowy Range, Wyoming, USA. Microclimate, physiology, and survivorship of first-year conifer seedlings of Pinus albicaulis Engelm., Picea engelmannii Parry, and Abies lasiocarpa Hook. were measured in response to manipulations of surrounding herb and tree cover, as well as water availability. Tree and herb cover had nearly additive effects on survivorship and photosynthesis of conifer seedlings, except under alleviated water stress. In P. albicaulis, photosynthesis was greater near compared with away from trees and herbs, and photosynthetic efficiency (Fv/Fm) increased under herb cover. Tree cover led to greater nighttime temperatures, soil water contents, and, like herb cover, shade from solar radiation for seedlings. We did not detect any negative responses of conifer seedlings to surrounding vegetation. Furthermore, the effect of surrounding vegetation on conifer establishment appeared dependent on the type of surrounding vegetation, the species of conifer, and microsite stress level. These factors may lead to variation in the way conifer seedlings interact with surrounding vegetation and could explain changes in the relative abundances of tree species during forest succession in ATEs.
Growth of three oak species during establishment of an agroforestry practice for watershed protection
Authors: Udawatta Ranjith P , Nygren Pekka , Garrett Harold E
Published: April 2005

Tree species that provide early benefits for farmers can serve to increase the adoption of temperate agroforestry practices. Growth of pin (Quercus palustris Muenchh.), swamp white (Quercus bicolor Willd.), and bur oak (Quercus macrocarpa Michx.) saplings was evaluated in an agroforestry practice designed for watershed protection in northern Missouri, USA, to identify species that provide early productive and protective functions. Large, containerized oak seedlings were planted in the center of 4.5-m-wide contour grass-legume strips established at 22.8- to 36.5-m intervals on a 4.44-ha watershed with a corn (Zea mays L.)  soybean (Glycine max (L.) Merr.) rotation. Sapling survival, height, and diameter growth were annually recorded during five growing seasons. Branch and leaf mass were also recorded in the two last measuring years. Preliminary assessment of rooting pattern was made based on the relative abundance of horizontal and vertical main roots. Mean shoot growth rate of pin oak was the highest during the whole study period, while swamp white and bur oak grew at the same rate until the fourth growing season. During the fifth growing season, growth rate of bur oak was the lowest. The root system of pin oak appears to be concentrated close to the tree, thus strengthening the buffer strips and competing least with the crop. The shallow root system of swamp white oak may best scavenge leaching nutrients from subsurface flow, thus reducing nonpoint source pollution. Sapling survival, growth rate, and rooting pattern suggest that pin oak and swamp white oak have a better potential for agroforestry practices in the Midwest than bur oak.
Effects of serial propagation, donor age, and genotype onChamaecyparis nootkatensisphysiology and growth traits
Authors: Krakowski J , Benowicz A , Russell J H , El-Kassaby Y A
Published: April 2005

Clonal replicates of Chamaecyparis nootkatensis (D. Don) Spach rooted cuttings (ramets) originating from pruned donor hedges (ortets) were grown for 3 years in a completely randomized common garden in southwestern British Columbia. Ramets were cut when ortets were 3, 7, 11, and 15 years old; selected ramets were also serially propagated for one, two, or three cycles, 4 years apart. Serial propagation and physiological and chronological aging effects of ortets on ramets were evaluated for photosynthetic and gas exchange parameters, rooting, height, biomass, and cold hardiness. Genotypic variation typically exceeded treatment differences. Excepting several genotypes, serial propagation had no significant effect on aging for pruned plants. Some genotypes had crooked or plagiotropic growth. These differences strengthened with ortet age, but serial propagation effects varied with genotype. Rooting success was similar across treatments. Detrimental effects of ortet aging were detected only at age 15. Clonal rooting differences were obscured by age 7; 15-year-old material had the lowest rooting success and smallest individuals. Serially propagated ramets from 15-year-old ortets had smaller shoots. No consistent trends were caused by age or serial propagation for other traits. Serial propagation can successfully mass produce tested elite yellow-cedar planting stock up to age 15.