bluuebunny/crossref_metadata_2025 huggingface dataset:
The Road More Traveled
Authors: Carsten Laura
Published: August 2003

Eating less can extend life-span in some organisms, but no one knows how food limitation exerts its effect. New work
reported
in the 12 April issue of
Science
shows that a gene linked to longevity overlaps with a dietary pathway, at least in fruit flies. The results suggest that different routes to long life share components.
Genes, Culture, and Aging Flies--What the Lab Can and Cannot Tell Us About Natural Genetic Variation for Senescence
Authors: Spencer Christine C. , Promislow Daniel E. L.
Published: August 2003

Model organisms cultured in the lab provide a powerful way to explore basic biological processes. However, lab culture can select for high early fecundity and dramatically shorten the life-span of lab organisms. Studies that use these short-lived organisms to identify aging-related genes might identify genes that simply restore the organism's original life-span. These results might not be fully relevant to wild populations. Experiments that reduce selection for shorter life-span or seek genes in naturally long-lived cohorts should lead to a more accurate understanding of aging.
The Naked Mole Rat--A New Record for the Oldest Living Rodent
Authors: Buffenstein Rochelle , Jarvis Jennifer U. M.
Published: August 2003

We report a new record for the world's longest-lived rodent, a male naked mole rat (
Heterocephalus glaber
). On the basis of his weight at capture, this animal was approximately 1 year old when collected near Mtito Andei, Kenya in July/August 1974. He died in April 2002, indicating that he lived for more than 28 years. As such, his life-span surpassed the previous longevity record for a rodent, which was held by a porcupine (
Hystrix brachyura
) that lived for 27 years and 4 months.
Mitochondrial Bioenergetics, Aging, and Aging-Related Disease
Authors: Nicholls David
Published: August 2003

In this Perspective, the author discusses some of the bioenergetic consequences of the various alterations in mitochondrial function that have been hypothesized to be associated with human aging and aging-related disease. Special focus is afforded to neurodegenerative disease.
Head Rush
Authors: Chen Ingfei
Published: August 2003

For energetic and good-humored William Sonntag, attacking the dullness of everyday routine--and just plain having fun--is one key to happiness in life as well as science. As a psychologist who branched out into endocrinology, Sonntag also epitomizes the notion that it takes all kinds of minds to decipher the science of aging. The Wake Forest University neuroendocrinologist has pioneered insights into the hormonal networks that shape aging-associated behavioral and cognitive changes.
Having It All After All
Authors: Davenport R. John
Published: August 2003

Bumping up amounts of the antitumor protein p53 protects mice against cancer, but it also accelerates aging. Now scientists reveal that beefing up the p53 force in a controlled manner can thwart cancer without speeding the animals' demise. Additional work is needed to verify that the mice don't age more rapidly than normal and that
p53
--and not another gene--underlies the effect.
β Be Ready
Authors: Davenport R. John
Published: August 2003

Steroid overpowers Alzheimer's protein (Alzheimer's disease; Neurodegeneration; Cholesterol).
Paper Chase
Authors: Leslie Mitch
Published: August 2003

Novel database charts path through calorie-restriction literature (Calorie restriction; Research tool).
Lipid Peroxidation and the Aging Process
Authors: Praticò Domenico
Published: August 2003

Consistent evidence supports the hypothesis that a progressive accumulation of oxidative damage to important cellular molecules is a fundamental mechanism involved in most senescence-associated alterations. Oxidative damage occurs when free radicals produced within an organism are not completely destroyed by the appropriate endogenous defense systems. Because lipids are a major component of living organisms and probably the first easy target of free radicals once they are produced, lipid peroxidation might play an important role in initiating and/or mediating some aspects of the aging process. It has been widely demonstrated that there is an age-associated increase in the steady-state concentrations of lipid peroxidation products. However, establishing the involvement of this phenomenon in the pathogenesis of the aging process has not been an easy task. The recent development of more reliable techniques to measure lipid peroxidation, together with more well-defined animal models of aging, should be of great help in future studies in this field. The current evidence for the presence and importance of lipid peroxidation in the aging process is discussed in this review.
Hungry for Science
Authors: Chen Ingfei
Published: August 2003

Edward Masoro's well-rounded expertise is the product of a career path that initially roved from one research area to another before finally becoming immersed in the study of dietary restriction. As the field of gerontology developed in the 1970s, he joined up and has become one of its luminaries. Now 78, his appetite for the subject continues to be whetted.
Heartsick Chromosomes
Authors: Leslie Mitch
Published: August 2003

Dwindling telomeres might weaken the aging heart (Cardiology; Telomeres).
No ALTernative
Authors: Davenport R. John
Published: August 2003

For hard-core cancer cells, only telomerase will do (Telomeres; Cancer).
Extra CRISPy, Please
Authors: Seydel Caroline
Published: August 2003

Hormone candidate staves off stress and helps worms live longer (Insulin-related signaling; Oxidative stress).
Rescue Code
Authors: Davenport R. John
Published: August 2003

DNA repair might depend on patterns of histone modifications (DNA repair; Chromatin structure).
The Constantly Changing Face of Chromatin
Authors: Vaquero Alejandro , Loyola Alejandra , Reinberg Danny
Published: August 2003

Many recent findings have altered our vision of chromatin and its role in the regulation of cellular functions. Our perspective concerning chromatin has changed to a much more complex, but also more dynamic, view of chromatin as an entity that is intimately involved in the regulation of a variety of cellular functions. In this review, we describe the various types of proteins that alter the structure and, therefore, the function of chromatin and discuss the possible role of chromatin in cell aging. The elucidation of the mechanisms that link chromatin to aging will be one of the most exciting and striking advancements in the coming years
Meeting Report--44th Annual
Drosophila
Research Conference
Authors: Cypser Jim
Published: August 2003

The ability to compare the genetics of aging in multiple model organisms is a powerful tool to dissect the biology of aging. Although the fruit fly has only about half again as many genes as the nematode worm, its tissue organization is much more complex. The emerging importance of tissue specificity and endocrine signaling in aging makes the fly a natural choice for many researchers interested in unraveling the next level of complexity of the aging process. This Perspective provides an overview of research related to aging that was described at the annual
Drosophila
conference held in Chicago in March 2003.
Immunity Challenge
Authors: Davenport R. John
Published: August 2003

As people get older, their immune systems falter. The elderly are more susceptible to infections than youngsters are, and hyperactive inflammatory responses appear to contribute to some age-associated illnesses, including Alzheimer's disease and atherosclerosis. Investigating the effect of aging on the immune system was once a scientific stepchild, but card-carrying immunologists are now tackling the problem head-on. Despite the immune system's complexity, researchers have started to make sense of how its components change with age. As the research progresses, scientists hope to bolster elderly people's response to infectious diseases and quiet the inflammation that can make aging a painful experience.
Growing Old, Bacterial Style
Authors: Leslie Mitch
Published: August 2003

Like us, some bacteria age, although scientists long believed they couldn't. Theoretical studies suggest that unequal division is the prerequisite for aging, and a new study of an asymmetrically dividing bacterium backs the argument. Starvation also provokes aging in some bugs, causing them to start producing proteins that are vulnerable to oxidative damage. Deprived bacteria deploy defenses against oxidation that are similar to those in worms and higher organisms. Bacteria's ability to survive brutal conditions might clue scientist in to ways to make our own cells resist aging.
Adult Cardiac Stem Cells--Where Do We Go from Here?
Authors: Edelberg Jay M. , Xaymardan Munira , Rafii Shahin , Hong Mun K.
Published: August 2003

A potential treatment for cardiovascular disease involves the transplantation of a patient's bone marrow stem cells into the heart of that same patient. In order to maximize the potential benefits to select patient populations, the continued clinical development of this technology will require a comprehensive understanding of the role(s) of the transplanted cells in the repair of damaged heart tissue as well as an understanding of which types of cardiac injury can be repaired by this approach. The widespread application of cardiovascular stem cell therapies, however, will likely be based on pharmacological approaches to enhance the capacity of endogenous bone marrow stem cells to provide for the replacement of cardiac muscle and vascular cells after myocardial injury.
From Cheeseburgers to Chest Pains
Authors: Seydel Caroline
Published: August 2003

Receptor might help fat clog arteries (Nuclear Receptors; Atherosclerosis).
Listening to the Song of Senescence
Authors: Chen Ingfei
Published: August 2003

Advised while in college to make his mark by heading into little-trodden scientific territory, Caleb Finch chose the study of aging. Although the prevailing scientific opinion at the time was that aging was only about vascular disease and cancer, Finch was convinced that mammalian aging is a regulated process that scientists can tease apart at the molecular level. He's spent the past 3 decades seeking to understand the genomic control of senescence in the brain--and playing in a bluegrass band.
Structure-(Dys)function Relationships in Mitochondrial Electron Transport Chain Complex II?
Authors: Kristal Bruce S. , Krasnikov Boris F.
Published: August 2003

It has been postulated that mitochondrially derived reactive oxygen species (ROS) play a major causative role in aging processes. The primary sources of these oxidants are believed to be complexes I and III of the electron transport chain, with little evidence supporting oxidant formation at complex II (succinate dehydrogenase). Mutation of a complex II protein has, however, been shown to cause increased oxidative stress and decreased life expectancy in the
Caenorhabditis elegans
mutant
mev-1
. A recent study by Yankovskaya and colleagues, in which the structure of
Escherichia coli
succinate dehydrogenase was determined, provides an explanation for these observations. Furthermore, these results suggest possible mechanisms by which electron leakage might occur at this site in the aged organism.
Subfield History: Caloric Restriction, Slowing Aging, and Extending Life
Authors: Masoro Edward J.
Published: August 2003

Caloric restriction has resulted in a consistent robust increase in the maximal length of life in mammalian species. This article reviews significant advances over the long history of research on calorie restriction and longevity.
Something for Almost Nothing
Authors: Seydel Caroline
Published: August 2003

Longevity's price is negotiable (Evolution; Costs of reproduction).
Requirement of Hippocampal Neurogenesis for the Behavioral Effects of Antidepressants
Authors: Santarelli Luca , Saxe Michael , Gross Cornelius , Surget Alexandre , Battaglia Fortunato , Dulawa Stephanie , Weisstaub Noelia , Lee James , Duman Ronald , Arancio Ottavio , Belzung Catherine , Hen René
Published: August 2003

Various chronic antidepressant treatments increase adult hippocampal neurogenesis, but the functional importance of this phenomenon remains unclear. Here, using genetic and radiological methods, we show that disrupting antidepressant-induced neurogenesis blocks behavioral responses to antidepressants. Serotonin 1A receptor null mice were insensitive to the neurogenic and behavioral effects of fluoxetine, a serotonin selective reuptake inhibitor. X-irradiation of a restricted region of mouse brain containing the hippocampus prevented the neurogenic and behavioral effects of two classes of antidepressants. These findings suggest that the behavioral effects of chronic antidepressants may be mediated by the stimulation of neurogenesis in the hippocampus.
Single Molecule Profiling of Alternative Pre-mRNA Splicing
Authors: Zhu Jun , Shendure Jay , Mitra Robi D. , Church George M.
Published: August 2003

Alternative pre-messenger RNA splicing is an important mechanism for generating protein diversity and may explain in part how mammalian complexity arises from a surprisingly small complement of genes. Here, we describe “digital polony exon profiling,”a single molecule–based technology for studying complex alternative pre-messenger RNA splicing. This technology allows researchers to monitor the combinatorial diversity of exon inclusion in individual transcripts. A minisequencing strategy provides single nucleotide resolution, and the digital nature of the technology allows quantitation of individual splicing variants. Digital polony exon profiling can be used to investigate the physiological and pathological roles of alternately spliced messenger RNAs, as well as the mechanisms by which these messenger RNAs are produced.
Chromosome Choreography: The Meiotic Ballet
Authors: Page Scott L. , Hawley R. Scott
Published: August 2003

The separation of homologous chromosomes during meiosis in eukaryotes is the physical basis of Mendelian inheritance. The core of the meiotic process is a specialized nuclear division (meiosis I) in which homologs pair with each other, recombine, and then segregate from each other. The processes of chromosome alignment and pairing allow for homolog recognition. Reciprocal meiotic recombination ensures meiotic chromosome segregation by converting sister chromatid cohesion into mechanisms that hold homologous chromosomes together. Finally, the ability of sister kinetochores to orient to a single pole at metaphase I allows the separation of homologs to two different daughter cells. Failures to properly accomplish this elegant chromosome dance result in aneuploidy, a major cause of miscarriage and birth defects in human beings.
Nervous System Targets of RNA Editing Identified by Comparative Genomics
Authors: Hoopengardner Barry , Bhalla Tarun , Staber Cynthia , Reenan Robert
Published: August 2003

An unknown number of precursor messenger RNAs undergo genetic recoding by modification of adenosine to inosine, a reaction catalyzed by the adenosine deaminases acting on RNA (ADARs). Discovery of these edited transcripts has always been serendipitous. Using comparative genomics, we identified a phylogenetic signature of RNA editing. We report the identification and experimental verification of 16 previously unknown ADAR target genes in the fruit fly
Drosophila
and one in humans—more than the sum total previously reported. All of these genes are involved in rapid electrical and chemical neurotransmission, and many of the edited sites recode conserved and functionally important amino acids. These results point to a pivotal role for RNA editing in nervous system function.
Prokaryotic Chromosomes and Disease
Authors: Hacker Jörg , Hentschel Ute , Dobrindt Ulrich
Published: August 2003

Recent insights into bacterial genome organization and function have improved our understanding of the nature of pathogenic bacteria and their ability to cause disease. It is becoming increasingly clear that the bacterial chromosome constantly undergoes structural changes due to gene acquisition and loss, recombination, and mutational events that have an impact on the pathogenic potential of the bacterium. Even though the bacterial genome includes additional genetic elements, the chromosome represents the most important entity in this context. Here, we will show that various processes of genomic instability have an influence on the many manifestations of infectious disease.
Observation of Long Supershear Rupture During the Magnitude 8.1 Kunlunshan Earthquake
Authors: Bouchon Michel , Vallée Martin
Published: August 2003

The 2001 Kunlunshan earthquake was an extraordinary event that produced a 400-km-long surface rupture. Regional broadband recordings of this event provide an opportunity to accurately observe the speed at which a fault ruptures during an earthquake, which has important implications for seismic risk and for understanding earthquake physics. We determined that rupture propagated on the 400-km-long fault at an average speed of 3.7 to 3.9 km/s, which exceeds the shear velocity of the brittle part of the crust. Rupture started at sub–Rayleigh wave velocity and became supershear, probably approaching 5 km/s, after about 100 km of propagation.
Compensation of the Birefringence of a Polymer by a Birefringent Crystal
Authors: Tagaya Akihiro , Ohkita Hisanori , Mukoh Masaki , Sakaguchi Ryuichi , Koike Yasuhiro
Published: August 2003

We report a method for compensating the birefringence of optical polymers by doping them with inorganic birefringent crystals. In this method, an inorganic birefringent material is chosen that has the opposite birefringence to that of the polymer and has rod-shaped crystals that are oriented when the polymer chains are oriented. The birefringence of the polymer is thus compensated by the opposing birefringence of the crystal. Birefringence is minimized in various polymer optical devices by adjusting process conditions, because it degrades the performance of devices. This method minimizes it, independent of process conditions, which potentially improves the productivity of devices.
Anatomy of the primitive bird Sapeornis chaoyangensis from the Early Cretaceous of Liaoning, China
Authors: Zhou Zhonghe , Zhang Fucheng
Published: August 2003

Two new, nearly completely articulated skeletons of Sapeornis chaoyangensis provide much new information about the anatomy of this basal avian, particularly in the skull, pectoral girdle, forelimb, and hind limb. This new material shows that the hand of Sapeornis, with a phalangeal formula of "232," was more derived than previously reconstructed. The skeleton of Sapeornis has several unique features, such as a distinctively elongated fenestra on the proximal end of the humerus, a robust furcula with a distinctive hypocleidum, and an elongated forelimb. Sapeornis exhibits a combination of derived and primitive features, including a short, robust non-strut-like coracoid and a fibula reaching the distal end of the tarsal joint (as in Archaeopteryx), a pygostyle, reduced manual digits, and a well-fused carpometacarpus (as in more advanced birds). These features further indicate the mosaic pattern in the early evolution of birds and confirm the basal position of Sapeornis near Archaeopteryx and Jeholornic in the phylogeny of early birds. The preservation of gastroliths in one of the new specimens also represents the first Chinese Mesozoic bird with such evidence, indicating a herbivorous feeding habit and providing further evidence for our understanding of the diet diversification in early avian evolution.
Reconnaissance sediment budgets for Lynn Valley, British Columbia: Holocene and contemporary time scales
Authors: Campbell David , Church Michael
Published: August 2003

Volumes of erosional and depositional landforms were estimated by reconnaissance methods in a steep, forested drainage basin in the Coast Mountains, British Columbia, to examine what insight might be gained into the sediment budget in the absence of direct measurements of sediment transfer processes. Sediment transfers in postglacial and contemporary time were inferred on hillslopes, from hillslopes to stream channels, and within stream channels. Data were collected by aerial photographic analysis and field observation. Postglacial sediment sources are major gullies created by debris slides and flows, failures in glaciolacustrine terraces, and stream channel degradation. Depositional landforms consist of talus slopes and colluvial and alluvial fans. Contemporary sediment sources include debris slides and flows in established gullies and minor processes on hillslopes. Debris slide and debris flow volumes were calculated, and other processes were estimated from regional values. Erosion rate averaged over postglacial time is 276 t·km2·a1(0.15 mm·a1surface lowering), with gullies and stream channel degradation contributing 170 and 82 t·km2·a1, respectively. A terminal alluvial fan provides an independent check of the results. In contemporary time, erosion rates are calculated to be 350 t·km2·a1, with debris flows and slides contributing nearly all of this sediment. The contemporary rate is probably perturbed by recent land use history. Mass-movement processes appear to be the dominant mechanism of sediment transfer and, contributions from Pleistocene valley deposits have declined significantly during Holocene time.
Geochemistry and SrNd isotopic composition of Eocene lamphrophyre dykes, southeastern British Columbia
Authors: Sevigny J H , Thériault R J
Published: August 2003

Mineral compositions, geochemical analyses, and SrNd isotopic compositions are reported for alkaline and calc-alkaline lamprophyres collected along the southern margin of the Valhalla Complex, southeastern British Columbia. The lamprophyres were emplaced during Eocene extension and lithospheric thinning associated with tectonic denudation of the Valhalla Complex. SiO2 contents range from 44.451.6 wt.%, K2O from 1.33.7 wt.%, and volatile contents (H2O + CO2 + SO3) from 0.84.6 wt.%. MgO and Cr contents are 9.57.6 wt.% and 540130 ppm, respectively, for samples with Mg#s between 0.69 and 0.65. Chrondrite-normalized rare-earth element patterns are strongly fractionated with Cen = 120375 and Ybn = 8.412.7. Alkaline lamprophyres contain biotite ± kaersutite ± calcic plagioclase and exhibit a limited range in initial 87Sr/86Sr (0.70510.7057), initial εNd (3.7 to 4.3), and TDM (766796 Ma). Calc-alkaline lamprophyres contain F-rich phlogopite and sodic plagioclase, and exhibit a wider range in initial 87Sr/86Sr (0.70640.7090), initial εNd (6.3 to 11.9), and TDM (9171,614 Ma). Alkaline lamprophyres are interpreted as uncontaminated melts derived from a long-term, volatile, and incompatible element-enriched mantle reservoir. Mantle enrichment coincided with continental rifting of western North America (ca. 760 Ma). The enriched mantle reservoir remained isolated for ~700 Ma. Lamprophyres were generated by partial melting of the mantle reservoir in response to adiabatic decompression and lithospheric thinning during Eocene extension.
n-Tree distance sampling for per-tree estimates with application to unequal-sized cluster sampling of increment core data
Authors: Lynch Thomas B , Wittwer Robert F
Published: August 2003

Samples from the n trees nearest to a point or plot center are sometimes used to estimate per-tree values such as age or growth from increment cores. Clutter et al. (J.L. Clutter, J.C. Fortson, L.V. Pienaar, G.H. Brister, and R.L. Bailey. 1983. Timber management: a quantitative approach. John Wiley & Sons, New York) indicated that this procedure can be biased because it is more likely to sample large trees occupying large amounts of space. This sampling procedure falls into the category of n-tree distance sampling in which the nth closest tree to a point defines a plot radius that can be used to estimate number of trees or amount of volume per hectare. When a ratio of n-tree per-hectare estimates is used to estimate per-tree attributes, the resulting estimator is a weighted average in which weights are the inverse of the n-tree sampling plot size. Since this ratio estimator essentially weights observations inversely with plot size, it is not subject to the objections of Clutter et al. (1983). This estimator is used to estimate age by diameter at breast height class for eastern cottonwood (Populus deltoides Bartr. ex Marsh.) on the Cimarron National Grassland.
Effects of spacing on the early growth of planted Fraxinus excelsior L.
Authors: Kerr Gary
Published: August 2003

The recent practice of planting broad-leaved trees at wide spacing (3 × 3 m) in Britain has generated debate concerning the effects of initial spacing on early growth (up to 5 years old) and form. The experiments described investigated the effects of spacing on the early growth of common ash (Fraxinus excelsior L.) using two replicate Nelder experiments at two sites, with spacings in the range 0.774.86 m. In both experiments, height, stem diameter, and stem volume decreased with increasing spacing; at one site, shoot and root dry mass also showed the same trend. These results suggest that better growth at closer spacings may be a silvicultural characteristic of ash. Analysis of the data showed that there was no intraspecific competition, and a number of hypotheses were examined that may explain the observed results.
Comparison of fixed-area plot designs for estimating stand characteristics and western spruce budworm damage in southwestern U.S.A. forests
Authors: Lynch Ann M
Published: August 2003

Various sampling designs were evaluated using data on stand density, stocking, mortality, and top kill, as influenced by the western spruce budworm (Choristoneura occidentalis Freeman) in 17 stands in New Mexico and Colorado. Efficiency improved as plot size decreased from 0.04 to 0.02 ha for all variables and sampling designs, except for 0.01-ha plots, which required extremely large sample sizes and were subject to bias. Cluster designs were much more efficient than simple random sampling designs, allowing twice the reduction in sample size than was gained by relaxing the allowable error from 10 to 15%. Clusters of two plots were as precise as clusters of three plots. Of the four variables evaluated, density required the largest sample sizes, followed by stocking, percent mortality (for stands where mortality exceeded 10%), and top kill. Few plots were necessary to ascertain that mortality was less than 10%. On average, 10 pairs of 0.02-ha plots would estimate density, stocking, and mortality within a 10% allowable error. A field check of density and stocking variables is recommended, and additional samples are suggested in stands with large percent standard errors associated with those variables.
Growth of first-order branches in Betula platyphylla saplings as related to the age, position, size, angle, and light availability of branches
Authors: Umeki Kiyoshi , Seino Tatsuyuki
Published: August 2003

The growth of first-order branches was measured in 25 saplings of Betula platyphylla Sukatchev var. japonica Hara growing under various light conditions in northern Hokkaido, northern Japan, and the effect of age, tip height, length, and angle of branches and light availability at the branch tips on branch growth were examined. Branch growth was evaluated as the total biomass growth of current-year long shoots within a first-order branch (TBG), the number of long shoots currently produced by the first-order branch (CSN), and the mean biomass of current-year long shoots within the first-order branch (MSG). In general, TBG, CSN, and MSG were negatively dependent on branch age and positively dependent on height, length, angle (from the horizontal), and light availability of the branch. The relationships between each of TBG, CSN, and MSG and the independent variables were individual specific. The dependency of TBG, CSN, and MSG on the light availability at the branch tips was affected by the maximum light availability at the individual level, suggesting that branch growth is affected not only by branch-level resources but also by conditions at the individual level. Based on these results, two concepts for understanding branch growth, branch autonomy and correlative inhibition, were discussed, and prediction models for TBG, CSN, and MSG were presented.
Changes in needle morphology of shade-tolerant seedlings after partial overstory canopy removal
Authors: Youngblood Andrew , Ferguson Dennis E
Published: August 2003

Recent studies with early-successional conifers have shown a correlation between changes in light regimes and changes in needle morphology. The objective of this study was to test the hypothesis that needles of late-successional conifers also respond to increased irradiance. We compared needle morphology of three co-occurring conifers, grand fir (Abies grandis (Dougl. ex D. Don) Lindl.), subalpine fir (Abies lasiocarpa (Hook.) Nutt.), and Engelmann spruce (Picea engelmannii Parry ex Engelm.). Morphological characteristics were examined for 4 years across three light environments: (1) open-canopy stands with 64% transmittance, (2) stands with 63% transmittance after a partial overstory removal treatment, and (3) closed-canopy stands with 29% transmittance. Needle width and length differed by year, but not by light environment. Mean stomatal density differed across years for all three species and increased with increasing irradiance for subalpine fir and Engelmann spruce. The number of mesophyll layers and the size of individual palisade mesophyll cells did not differ among the different light environments. The number of epidermis cell layers in each species was insensitive to changes in light environment and time. Our results indicate that these three conifers were unable to morphologically adapt their needles to an increase in light transmission caused by the partial removal of overstory canopies.
Characteristics of subalpine fir susceptible to attack by western balsam bark beetle (Coleoptera: Scolytidae)
Authors: Bleiker Katherine P , Lindgren B Staffan , Maclauchlan Lorraine E
Published: August 2003

A diameter distribution survey at three sites in the interior of British Columbia revealed that the western balsam bark beetle (Dryocoetes confusus Swaine) predominately attacked trees from the three to four largest diameter classes at each site. However, the mean diameter of attacked trees was significantly different among sites, indicating that factors other than diameter contribute to the susceptibility of subalpine fir (Abies lasiocarpa (Hook.) Nutt.) to the western balsam bark beetle. A number of tree characteristics, including measures of growth, age, crown size, and phloem thickness, were compared among a total of 22 successfully attacked, 26 unsuccessfully attacked, and 28 unattacked trees at three sites. Of the 12 tree characteristics measured, five showed significant differences between successfully attacked and unattacked trees. Successfully attacked trees had a lower percentage of the bole covered with constant crown, lower crown volume, lower radial growth in the last 5 years, and were older than unattacked trees. Successfully attacked trees also produced less induced resinosis than unsuccessfully attacked trees. The results of this study suggest that western balsam bark beetle mortality may be limited by the presence and distribution of susceptible hosts. The study also identifies a number of variables that could be used in a susceptibility and risk rating model for western balsam bark beetle.
Chemical and mechanical site preparation: effects onPinus contortagrowth, physiology, and microsite quality on grassy, steep forest sites in British Columbia
Authors: Simard Suzanne W , Jones Melanie D , Durall Daniel M , Hope Graeme D , Stathers Robert J , Sorensen NaDene S , Zimonick Barbara J
Published: August 2003

Site preparation alleviates the effects of pinegrass (Calamagrostis rubescens Buckl.) interference on conifers in British Columbia, but little is known about interference mechanisms and appropriate site preparation methods for steep slopes. In this study, lodgepole pine (Pinus contorta Dougl. ex Loud.) was planted in pinegrass controls and small (90 × 90 cm) and large (180 × 90 cm) patches where (i) only pinegrass was removed using glyphosate or (ii) both pinegrass and the forest floor were removed using an excavator. Treatments were replicated three times in east- and west-facing clearcuts and effects were followed for 9 years. Two-year pine survival was 78% in the control and >97% in large patches. All patch treatments improved pine growth, but it was greatest in large chemical patches during the initial 6 years and in both large patch treatments thereafter. Removal of the forest floor reduced foliar and soil nutrients, increased bulk density and soil water availability, decreased porosity and aggregate stability, and reduced ectomycorrhizal diversity and richness. These changes were not observed in chemical patches. All patch treatments increased soil temperatures and reduced frost relative to controls, but more so in large patches. Pinegrass can suppress early pine performance, and large chemical patches that retain the forest floor are best for relieving the multiple environmental stressors.
Effects of Tsuga canadensis mortality on soil water chemistry and understory vegetation: possible consequences of an invasive insect herbivore
Authors: Yorks Thad E , Leopold Donald J , Raynal Dudley J
Published: August 2003

Soil water chemistry and vegetation were monitored for almost 1 year before and 4 years after treatment in two healthy Tsuga canadensis (L.) Carrière (eastern hemlock) stands and two T. canadensis stands subjected to a girdling treatment. The girdling treatment was applied to simulate infestation and mortality by the introduced pest Adelges tsugae Annand. The girdling of T. canadensis trees resulted in elevated concentrations of NO3 and most cations in soil water within 23 months, and concentrations of several ions remained high relative to control stands for the duration of the study (e.g., NO3, Ca2+, K+, Mg2+). Maximum mean monthly concentrations were generally observed 1218 months after girdling (e.g., 4732272 µequiv. NO3/L, 22126 µequiv. NH4+/L). Maximum mean annual weighted ion concentrations and fluxes (e.g., 236 µequiv. NO3/L and 18 kg NO3-N/ha, respectively) were observed 23 years after girdling and were comparable to values reported in the literature regarding clear-cutting effects on stream water ion concentrations and losses. Betula alleghaniensis Britt. seedling densities and percent cover of several herbaceous species (Dennstaedtia punctilobula (Michx.) Moore, Dryopteris intermedia (Muhl.) A. Gray, Oxalis acetosella L., Thelypteris noveboracensis (L.) Nieuwl.) increased in response to T. canadensis mortality. Total percent cover of understory vegetation more than doubled in the first 3 years after girdling.
Stream temperatures in two shaded reaches below cutblocks and logging roads: downstream cooling linked to subsurface hydrology
Authors: Story A , Moore R D , Macdonald J S
Published: August 2003

This study examined water temperature patterns and their physical controls for two small, clearing-heated streams in shaded reaches downstream of all forestry activity. Field observations were made during JulyAugust 2000 in the central interior of British Columbia, Canada. For both reaches, downstream cooling of up to 4°C had been observed during daytime over distances of ~200 m. Radiative and convective exchanges of energy at heavily shaded sites on both reaches represented a net input of heat during most afternoons and therefore could not explain the observed cooling. In one stream, the greatest downstream cooling occurred when streamflow at the upstream site dropped below about 5 L·s1. At those times, temperatures at the downstream site were controlled mainly by local inflow of groundwater, because the warmer water from upstream was lost by infiltration in the upper 150 m of the reach. Warming often occurred in the upper subreach, where cool groundwater did not interact with the channel. At the second stream, creek temperature patterns were comparatively stable. Energy balance estimates from one afternoon suggested that groundwater inflow caused about 40% of the ~3°C gross cooling effect in the daily maximum temperature, whereas bed heat conduction and hyporheic exchange caused about 60%.
Sources of large wood in the main stem of a fourth-order watershed in coastal Oregon
Authors: Reeves Gordon H , Burnett Kelly M , McGarry Edward V
Published: August 2003

We compared the contribution of large wood from different sources and wood distributions among channel zones of influence in a relatively pristine fourth-order watershed in the central Coast Range of Oregon. Wood in the main stem of Cummins Creek was identified as coming from either (i) streamside sources immediately adjacent to the channel or (ii) upslope sources delivered by landslides or debris flows more than 90 m from the channel. About 65% of the number of pieces and 46% of the estimated volume of wood were from upslope sources. Streamside sources contributed about 35% of the number of pieces and 54% of the estimated volume of wood. The estimated mean volume of upslope-derived pieces was about one-third that of streamside-derived pieces. Upslope-derived pieces were located primarily in the middle stream reaches and in the zones of influence that had the most contact with the low-flow channel. Streamside-derived pieces were more evenly distributed among the examined reaches and were predominately in the influence zones that had the least contact with the low-flow channel. Our findings suggest that previous studies that examined only streamside sources of wood have limited applications when designing and evaluating riparian management approaches in landslide-prone areas. The failure to recognize the potential sources of wood from upslope areas is a possible reason for the decline of large wood in streams in the Pacific Northwest.
A Taxonomy for Artificial Embryogeny
Authors: Stanley Kenneth O. , Miikkulainen Risto
Published: August 2003

A major challenge for evolutionary computation is to evolve phenotypes such as neural networks, sensory systems, or motor controllers at the same level of complexity as found in biological organisms. In order to meet this challenge, many researchers are proposing indirect encodings, that is, evolutionary mechanisms where the same genes are used multiple times in the process of building a phenotype. Such gene reuse allows compact representations of very complex phenotypes. Development is a natural choice for implementing indirect encodings, if only because nature itself uses this very process. Motivated by the development of embryos in nature, we define artificial embryogeny (AE) as the subdiscipline of evolutionary computation (EC) in which phenotypes undergo a developmental phase. An increasing number of AE systems are currently being developed, and a need has arisen for a principled approach to comparing and contrasting, and ultimately building, such systems. Thus, in this paper, we develop a principled taxonomy for AE. This taxonomy provides a unified context for long-term research in AE, so that implementation decisions can be compared and contrasted along known dimensions in the design space of embryogenic systems. It also allows predicting how the settings of various AE parameters affect the capacity to efficiently evolve complex phenotypes.
Intelligent Meaning Creation in a Clumpy World Helps Communication
Authors: Smith Andrew D. M.
Published: August 2003

This article investigates the problem of how language learners decipher what words mean. In many recent models of language evolution, agents are provided with innate meanings a priori and explicitly transfer them to each other as part of the communication process. By contrast, I investigate how successful communication systems can emerge without innate or transferable meanings, and show that this is dependent on the agents developing highly synchronized conceptual systems. I present experiments with various cognitive, communicative, and environmental factors which affect the likelihood of agents achieving meaning synchronization and demonstrate that an intelligent meaning creation strategy in a clumpy world leads to the highest level of meaning similarity between agents.
Introduction
Authors: Martin Alison
Published: August 2003

This article provides an introduction to Irigaray's work, dealing with the questions of cultural difference that a culture of sexual difference raises. It sets out the main elements of Irigaray's thought and work without assuming any prior knowledge of it. It discusses her status as a French thinker and her reception in Anglo-academia, emphasizing the influence of Heidegger and Hegel on her thinking, and questioning her categorization as a `French feminist' and exponent of `feminine writing'. It highlights Irigaray's work in the 1990s, particularly its more political aspects. Her proposals for a democracy based on the man-woman couple are discussed, as is her relation to Italian feminism and her work within the European Parliament to bring about a sexed definition of citizenship. Irigaray is presented as a political philosopher of change who is concerned with a future of justice for everyone.
The Deep Structure of Presidential Space
Authors: Andrew William L. , Cheek Sidney M. , McCreary Samuel M. , Goodsell Charles T.
Published: August 2003

The “deep structure” of presidential space refers to underlying, given characteristics of the physical setting of the U.S. presidency. The institutionalized presidency has expanded greatly in the past century. At the same time, the historical home of the presidency, the White House complex, has not expanded appreciably. As a result, the institution’s office space is extremely crowded, and added room has been obtained in a successive series of nearby Washington buildings. The consequence has been to create several differentiated spatial zones, where imputed power decreases as one gets farther from the oval office. Hence, great pressure exists to be as near as possible to this center of power, creating intense space rivalries, an exaggerated sense of spatial hierarchy, and dysfunctional separation of senior officials from their staffs.
Managerial Work and Management Reform in Senegal
Authors: Lubatkin Michael H. , Vengroff Richard , Ndiaye Momar , Veiga John F.
Published: August 2003

The application of Western management techniques to countries in the very early stages of economic development remains a subject of debate. Building on the works of Montgomery in the Southern African Development Coordination Conference countries and of Vengroff in the Central African Republic, the authors examine the skill requirements among Senegalese managers from nine different employment situations: upper, middle, and lower levels at public, private, and parastatal organizations. They then extend their work by examining the same managers as to their normative beliefs and attitudes about managerial work. They conclude with implications of these findings for the design and implementation of management-training programs and the possibilities for the success of management reform efforts.
Musical Performance: Crux or Curse of Music Education?
Authors: Mills Janet
Published: August 2003

This article examines whether musical performance is the crux or curse of music education. The author reviews research related to this debate and argues that it is problematic for teachers to attempt to address musical performance without taking a broader musical context into consideration.
Investigating Expressive Timing and Dynamics in Recorded Cello Performances
Authors: Hong Ju-Lee
Published: August 2003

During the past decade, the articulation of expressive devices in musical performance has received serious scholarly attention from researchers, who have examined performance empirically and/or systematically. In particular, there have been a number of researchers (e.g. Todd; Clarke and Windsor; Windsor and Clarke) who have investigated how artificial systems can simulate human expressive performance. In this research note, the author presents a re-examination of the motor process between expressive timing and dynamics first analysed by Todd in 1992. The initial investigation is based on a performance analysis of timing and dynamics in 20 selected commercial recordings of J.S. Bach's Sarabande from the C major Cello Suite BWV1009. The author suggests an alternative empirical approach to studying the model of performance by investigating how expert cellists in recordings have practised the motor process between expressive timing and dynamics.
Theory after the Postmodern Condition
Authors: Jones Campbell
Published: August 2003

In the context of an apparent crisis of grand narratives and continuing reference to the postmodern condition, this article considers aspects of the development of theory in organization studies over the past decade and offers some reflections on prospects for the future. These issues are presented via a reading of Jean-François Lyotard's The Postmodern Condition and the way that this book has been received in organization studies. This `paralogical' reading contests a number of widespread assumptions in organization studies about Lyotard and French theory, and provides the opening for a discussion of the future of theory in organization studies. This involves asking questions about (1) the consumption of theory in organization studies; (2) the concepts in currency in organization studies today; and (3) the shifting divisions of organization studies.
The World of Torture:
Authors: Crelinsten Ronald D.
Published: August 2003

This article argues that torture is made possible, despite almost universal condemnation in legal codes, by the construction of a closed world that permits the use of torture against specific members of society defined as enemies. The article examines how a torture-sustaining reality is constructed (causes), how it is maintained and institutionalized (consequences), how it can be dismantled or deconstructed (cures) and, ultimately, how it can be prevented from forming in the first place (prevention, early warning). For each phase, the article looks at those variables that are most pertinent for three types of actors: perpetrators, victims and bystanders. It also examines those variables that operate primarily at the domestic level and those that operate at the international level.
Beyond the Metaphor:
Authors: McEvoy Kieran
Published: August 2003

Using Northern Ireland as a case study, this article explores the relationship between human rights and criminological discourses concerning paramilitary abuses. The article begins with a critical introduction to peacemaking criminology. It then explores four overlapping styles of interventions designed to mitigate paramilitary violence. These include, attempts to hold paramilitaries accountable through humanitarian law; the use of human rights as a rhetorical base for claimsmaking; attempts to encourage the internalization of human rights discourses through a process of political osmosis; and interventions which have been guided primarily by criminological concerns. The article concludes by suggesting a schema for a `new' version of peacemaking criminology that intersects with and builds upon the human rights paradigm in transforming political or ethnic conflicts.