bluuebunny/crossref_metadata_2025 huggingface dataset:
Caloric Restriction in
trans
Authors: Kristal Bruce S. , Paolucci Ugo
Published: August 2003

Caloric (or dietary) restriction (CR) is the most potent, robust, and reproducible known means of extending longevity and decreasing morbidity in laboratory mammals. Two of the major questions faced by researchers in this field are the applicability to humans and the biochemical mechanism(s) involved in the actions of CR. Studies in nonhuman primates are beginning to address the former; studies in phylogenetically lower organisms such as yeast and
Drosophila
are beginning to address the latter. de Cabo and colleagues now provide evidence that some aspects of CR can be reproduced in mammalian tissue culture cells exposed to sera from rats and monkeys subjected to CR. This work presents the initial development of a new model with which to approach mechanistic studies of CR and provides a new form of direct evidence that CR exerts at least some of its effects in
trans
.
Funded Up and Raring to Go
Authors: Chen Ingfei
Published: August 2003

Founded in 1981, the nonprofit American Federation for Aging Research (AFAR) supports research into the basic mechanisms of aging and age-related diseases. It is working to bring new scientists into the discipline. This year, AFAR is giving away just more than $7 million to 130 scientists at varying career stages, from grad students to junior faculty. The winning grant proposals range from investigations of oxidative damage in long-lived bats to the role of a suspect protein, β-secretase, in Alzheimer's disease.
The Molecular Basis of Age-Related Kidney Disease
Authors: Zheng Feng , Plati Anna Rita , Banerjee Anita , Elliot Sharon , Striker Liliane J. , Striker Gary E.
Published: August 2003

Renal disease affects 11% of people in the United States over the age of 65, not including those with diabetes or hypertension. Although glomerular disease is the most common underlying etiology of age-related renal dysfunction, the cause of glomerular disease and whether it is the only contributor to renal failure are not known. Our studies in female mice show that renal disease in the postmenopausal period is associated with progressive glomerular enlargement and scarring, as well as abnormal renal function. To study the underlying causes of aging-related glomerular disease, we isolated and characterized glomerular smooth muscle (mesangial) cells from female mice of various ages. We found that the cells from older mice exhibit a variety of phenotypic changes, including increased concentrations of p27, a protein that serves to inhibit progression from the G
1
to the S phase of the cell cycle. Because the bone marrow (BM) contains mesangial cell progenitors that can transfer the donor glomerular phenotype (normal or diseased) to recipients, we exchanged BM between postmenopausal and premenopausal mice and found that aging-related glomerular enlargement and scarring are transferred to young recipient glomeruli. In addition, BM from normal, young donors led to the regression of aging-related glomerular disease in postmenopausal recipients; namely, both glomerular enlargement and scarring were reduced. Thus, aging-related glomerular disease is an entity distinct from all other causes of renal disease, is characterized by phenotypic changes in mesangial cell progenitors, and is reversible when the phenotype of the progenitors is returned to normal.
Endless Drive
Authors: Chen Ingfei
Published: August 2003

Geneticist Vicki Lundblad is a major force in the study of telomeres, the DNA-and-protein caps that guard chromosome tips. Her scientific life began at home in her preteen years with thin-layer chromatography assays; more recently it has included seminal contributions in deciphering how cells prevent their telomeres from dwindling away. Colleagues admire her "uncommon common sense" that guides her research as well as her mentoring.
Mouse and Human Cells Versus Oxygen
Authors: Hornsby Peter J.
Published: August 2003

Mice and humans are at opposite ends of the mammalian spectrum of longevity. A major question in biology is whether this difference can be accounted for by differences in the properties of cells from these two species. A new publication from Judith Campisi's lab reports that human cells in culture are more resistant than mouse cells to the damaging effects of 20% oxygen. The greater burden of DNA damage sustained by mouse cells causes them to rapidly enter a phase of culture in which most cells enter permanent growth arrest (replicative senescence). However, some mouse cells usually escape from senescence and then grow into an immortal cell line. This never happens in human fibroblast cell cultures. Human cells also eventually enter replicative senescence in culture, but this phenomenon is caused by shortening of telomeres and not by DNA damage of the type responsible for mouse cell senescence. Human fibroblasts never spontaneously escape from senescence. This Perspective reviews differences between mouse and human cells that could account for these differences in behavior. Some evidence indicates that human cells are generally more resistant than mouse cells to oxidative damage to DNA, but more needs to be done to confirm this finding and to understand the underlying mechanisms. Whether or not there are differences in the amount of DNA damage caused by oxygen or in the early phase of repair, there may be important differences in the later consequences of DNA damage. Mouse cells appear to be able to continue to divide with DNA damage that has not been repaired or has been misrepaired, and becomes fixed in the form of chromosomal abnormalities. The checkpoints that cause cells to stop dividing when chromosomes develop abnormalities (aberrations or shortened telomeres) appear to operate more efficiently in human cells. Much more work is needed to understand the basis for these differences and the implications for aging and cancer.
Diverse Dealings of the Werner Helicase/Nuclease
Authors: Cheng Wen-Hsing , Bohr Vilhelm A.
Published: August 2003

The human Werner syndrome is a model for the process of aging. The protein that is mutated in Werner syndrome, WRN, exhibits three catalytic activities: a 3′-to-5′ helicase, a 3′-to-5′ exonuclease, and an adenosine triphosphatase activity. WRN interacts with a variety of proteins and has been implicated in many aspects of DNA metabolism. A recent paper by Chen
et al.
published in the August 2003 issue of
Aging Cell
sheds some light on the multifunctional nature of WRN. It suggests that WRN may be considered as a structural protein, providing a plausible conceptual basis for the many WRN protein-protein interactions.
Healing Power
Authors: Seydel Caroline
Published: August 2003

Protein kick-starts skin's repair process (Wound healing; Growth factors; Therapeutics).
Down But Not Out
Authors: Beckman Mary
Published: August 2003

Stripping chemical ornaments can reactivate cancer-thwarting gene (Cancer; Chromatin).
The Contribution of Functional Brain Imaging to Our Understanding of Cognitive Aging
Authors: Gazzaley Adam , D'Esposito Mark
Published: August 2003

The study of cognitive aging seeks to determine the psychological and neural mechanisms underlying age-related decline in cognitive performance. New methods in functional brain imaging are beginning to provide possible answers to questions regarding age-related cognitive decline.
Course Outline
Authors: Willis Judy
Published: August 2003

For this course on the biology of aging, Judy Willis of the University of Georgia, Athens, supplements lectures with selected articles from SAGE KE in lieu of a textbook. View the course outline and click to read articles for each topic.

[Course Outline]
Keeping It Together
Authors: Ramsayer Kate
Published: August 2003

Small molecules mimic beneficial mutation and might protect against amyloid disease (Amyloid; Energetics; Cardiology).
Think Positive
Authors: Seydel Caroline
Published: August 2003

New genomewide search technique turns up genes that promote long life rather than curtail it (Conditional mutants; Protein transport; Metabolism).
Stress for Success
Authors: Leslie Mitch
Published: August 2003

Researchers in aging and other fields are warming to hormesis, the idea that moderate doses of heat, toxicants, radiation, or other stresses are helpful. The notion fell into disrepute because of early supporters' belief in homeopathy, but a plethora of data supports it. Experts on aging are now trying to dissect the molecular pathways behind hormesis to find out how they increase life-span and bestow other benefits. The small amount investigators have learned suggests that hormesis might erect some of the same defenses as do life-extending mutations, such as increased amounts of heat shock proteins that prevent other proteins from unfolding. Further research might allow doctors to use hormesis to aid aging patients.
Farewell to Fatherhood
Authors: Leslie Mitch
Published: August 2003

In men, sperm vitality goes the way of the hairline and the taut stomach (Infertility).
Acing the Stress Test
Authors: Ramsayer Kate
Published: August 2003

Life-extending genetic alteration prevents artery damage (Oxidative stress; Atherosclerosis).
Subfield History: Use of Model Organisms in the Search for Human Aging Genes
Authors: Warner Huber R.
Published: August 2003

The National Institute on Aging (NIA) started a program in 1993 to identify genes involved in the regulation of longevity in a variety of species, including yeast, nematodes, fruit flies, and mice. The initial success of this program has attracted the interest of many investigators working with these organisms. Of primary interest are single-gene mutants that have identified genes and processes involved in longevity regulation across species. These processes include the insulin-like signaling pathway, stress resistance, and most recently, chromosome and nuclear architecture. Mutations in genes that regulate these processes indirectly are also being identified in this program. The ultimate goal of this program is to extend these results to humans to identify the major biological risk factors for age-related decline of function in human physiological systems.
Wake-Up Call
Authors: Chen Ingfei
Published: August 2003

Theoretical biologist Aubrey de Grey thinks aging is an uncivilized phenomenon that neither he nor anyone else should have to put up with. A computer scientist by training, he got converted to the field of biology in part by asking his geneticist wife about her work. Although he doesn't do benchwork himself, by poring over the literature and formulating new--and often controversial--ideas, he is prodding gerontologists toward the development of medicines to reverse aging.
Resistance Is Futile
Authors: Leslie Mitch
Published: August 2003

Insulin resistance doesn't presage diabetes unless the illness runs in the family (Diabetes)
Get Wild
Authors: Davenport R. John
Published: August 2003

Numerous genetic alterations can profoundly extend the life-span of model organisms. But some researchers question whether the life-stretching effect is just a peculiarity of the lab and whether the same mutations influence survival in a natural environment. Scientists are beginning to test how long-lived animals fare in natural settings and whether life-extending mutations have a fighting chance in nature. The results suggest that the advantage depends on environment and other genes, and they could help guide the design of therapies for humans.
Dietary Drawbacks
Authors: Hopkin Karen
Published: August 2003

The benefits of dietary restriction are well documented: Creatures that consume one-third fewer calories are leaner, livelier, and longer lived than their fully fed kin. But such drastic dieting also has a dark side. Restricted animals get chilled and pick up infections unusually easily, and they're less fertile than their more portly compatriots are. Furthermore, cutting calories doesn't enhance longevity in all animals, according to several studies. These observations have many researchers wondering what dietary restriction--or a drug that mimics its effects--might do for people who are hoping to live longer and healthier lives.
Bridge Inside Troubled Cells
Authors: Beckman Mary
Published: August 2003

Stress unites protective proteins by forming atomic ties (Heat shock; Oxidative stress).
Into Thick Air
Authors: Davenport R. John
Published: August 2003

Polyamines help bacteria survive oxygen overload (Oxidative damage).
Gain on Pain
Authors: Beckman Mary
Published: August 2003

Scientists identify portion of molecule that relays pain from damaged nerves (Neuropathy; Pain).
Germline Genomes--A Biological Fountain of Youth?
Authors: Walter Christi A. , Walter Ronald B. , McCarrey John R.
Published: August 2003

The fusion of male- and female-derived gametes initiates the phenomenal process of producing a highly complex mammalian organism. Successful reproduction is so important that mammals invoke a battery of protective mechanisms for the germ cell lineages that function to maximize genetic integrity while still allowing genetic diversity and adaptation. Protective mechanisms likely include, but are not limited to, robust DNA repair to safeguard genetic integrity and apoptosis to remove cells with intolerable levels of DNA damage. Analyses of spontaneous mutant frequencies are generally consistent with germline DNA being stringently maintained relative to somatic tissues. Despite the rigorous protection afforded germ cells, genetic integrity is observed to decline with increased maternal and paternal age. It is not yet clear whether cells in the germ line truly age or whether other processes decline or become dysfunctional with age. For example, in a younger animal, the differentiation and/or utilization of germ cells with lower genetic integrity might be disallowed, whereas in an older animal, such cells might slip past these quality-control mechanisms.
Functions of Eukaryotic DNA Polymerases
Authors: Shcherbakova Polina V. , Bebenek Katarzyna , Kunkel Thomas A.
Published: August 2003

A major function of DNA polymerases is to accurately replicate the six billion nucleotides that constitute the human genome. This task is complicated by the fact that the genome is constantly challenged by a variety of endogenous and exogenous DNA-damaging agents. DNA damage can block DNA replication or alter base coding potential, resulting in mutations. In addition, the accumulation of damage in nonreplicating DNA can affect gene expression, which leads to the malfunction of many cellular processes. A number of DNA repair systems operate in cells to remove DNA lesions, and several DNA polymerases are known to be the key components of these repair systems. In the past few years, a number of novel DNA polymerases have been discovered that likely function in replicative bypass of DNA damage missed by DNA repair enzymes or in specialized forms of repair. Furthermore, DNA polymerases can act as sensors in cell cycle checkpoint pathways that prevent entry into mitosis until damaged DNA is repaired and replication is completed. The list of DNA template-dependent eukaryotic DNA polymerases now consists of 14 enzymes with amazingly different properties. In this review, we discuss the possible functions of these polymerases in DNA damage repair, the replication of intact and damaged chromosomes, and cell cycle checkpoints.
Protective Parents
Authors: Davenport R. John
Published: August 2003

Yeast moms bear brunt of protein damage (Oxidative damage; Replicative life span).
Live Long and Ferment
Authors: Leslie Mitch
Published: August 2003

Antioxidant enzyme helps yeast live to ripe old age (Oxidative stress; Genetics).
Clearance Cell
Authors: Davenport R. John
Published: August 2003

Astrocytes melt amyloid plaques (Alzheimer's disease; Neurodegeneration).
Unearthing Loci That Influence Life Span
Authors: Tatar Marc
Published: August 2003

It is known that certain hormones are involved in determining longevity (for example, insulin and insulin-like growth factor). Results presented in a paper published in this week's issue of
Science
allow us to add steroid hormones to this list. Anne Simon and colleagues show for the first time that a sterol hormone--ecdysone of the fly
Drosophila melanogaster
--regulates life span. In this Perspective, I discuss the implications of this result in the context of gene regulation and mechanisms of aging.
Giving Fish a Hand
Authors: Shubin Neil H.
Published: August 2003

Gaining Ground
The Origin and Evolution of Tetrapods. by Jennifer A. Clack. Indiana University Press, Bloomington, IN, 2002. 383 pp. $49.95, £37.95. ISBN 0-253-34054-3.

Through her discussion of when, where, and how vertebrates first came ashore, Clack offers an up-to-date account of our understanding of the fish to tetrapod transition, one of the classic evolutionary stories.
An Experimental Study of Search in Global Social Networks
Authors: Dodds Peter Sheridan , Muhamad Roby , Watts Duncan J.
Published: August 2003

We report on a global social-search experiment in which more than 60,000 e-mail users attempted to reach one of 18 target persons in 13 countries by forwarding messages to acquaintances. We find that successful social search is conducted primarily through intermediate to weak strength ties, does not require highly connected “hubs” to succeed, and, in contrast to unsuccessful social search, disproportionately relies on professional relationships. By accounting for the attrition of message chains, we estimate that social searches can reach their targets in a median of five to seven steps, depending on the separation of source and target, although small variations in chain lengths and participation rates generate large differences in target reachability. We conclude that although global social networks are, in principle, searchable, actual success depends sensitively on individual incentives.
Thermohaline Fine Structure in an Oceanographic Front from Seismic Reflection Profiling
Authors: Holbrook W. Steven , Páramo Pedro , Pearse Scott , Schmitt Raymond W.
Published: August 2003

We present acoustic images of oceanic thermohaline structure created from marine seismic reflection profiles across the major oceanographic front between the Labrador Current and the North Atlantic Current. The images show that distinct water masses can be mapped, and their internal structure imaged, using low-frequency acoustic reflections from sound speed contrasts at interfaces across which temperature changes. The warm/cold front is characterized by east-dipping reflections generated by thermohaline intrusions in the uppermost 1000 meters of the ocean. Our results imply that marine seismic reflection techniques can provide excellent spatial resolution of important oceanic phenomena, including thermohaline intrusions, internal waves, and eddies.
Bacterial Sex: Playing Voyeurs 50 Years Later
Authors: Kohiyama Masamichi , Hiraga Sota , Matic Ivan , Radman Miroslav
Published: August 2003

The concept of chromosomes with a ring structure was born during the early studies of bacterial sexuality, and the discovery of fertility factors— episomes or plasmids—provided much later the key tools for gene cloning and biotechnology. But the plasmid-mediated transfer of antibiotic and other resistances, as well as pathogenicity, has served bacteria well in their own adaptive evolution.
Inhibition of Neuroepithelial Patched-Induced Apoptosis by Sonic Hedgehog
Authors: Thibert Chantal , Teillet Marie-Aimée , Lapointe Françoise , Mazelin Laetitia , Le Douarin Nicole M. , Mehlen Patrick
Published: August 2003

During early development in vertebrates, Sonic hedgehog (Shh) is produced by the notochord and the floor plate. A ventrodorsal gradient of Shh directs ventrodorsal patterning of the neural tube. However, Shh is also required for the survival of neuroepithelial cells. We show that Patched (Ptc) induces apoptotic cell death unless its ligand Shh is present to block the signal. Moreover, the blockade of Ptc-induced cell death partly rescues the chick spinal cord defect provoked by Shh deprivation. Thus, the proapoptotic activity of unbound Ptc and the positive effect of Shh-bound Ptc on cell differentiation probably cooperate to achieve the appropriate spinal cord development.
Synthesis of Zeolite As Ordered Multicrystal Arrays
Authors: Lee Jin Seok , Lee Yun-Jo , Tae Eunju Lee , Park Yong Soo , Yoon Kyung Byung
Published: August 2003

Zeolites are crystalline nanoporous aluminosilicates widely used in industry. In order for zeolites to find applications as innovative materials, they need to be organized into large two- and three-dimensional (2D and 3D) arrays. We report that uniformly aligned polyurethane films can serve as templates for the synthesis of uniformly aligned 2D and possibly 3D arrays of silicalite-1 crystals, in which the orientations of the crystals are controlled by the nature of the polymers. We propose that the supramolecularly organized organic-inorganic composites that consist of the hydrolyzed organic products and the seed crystals are responsible for this phenomenon.
Geology and geochemistry of the Clear Creek intrusion-related gold occurrences, Tintina Gold Province, Yukon, Canada
Authors: Marsh Erin E , Goldfarb Richard J , Hart Craig J.R , Johnson Craig A
Published: August 2003

The Clear Creek gold occurrences lie within deformed lower greenschist-facies rocks of the western Selwyn basin. They consist of auriferous, sheeted quartz veins that cut six Cretaceous stocks and their hornfels. The veins contain 12% combined pyrite and arsenopyrite, with lesser pyrrhotite, bismuthinite, and scheelite, as well as 25 g/t Au. New 40Ar/39Ar geochronology of hydrothermal micas indicates that the veins formed within 12 million years of granitoid emplacement. Fluid inclusion microthermometry defines a parent ore fluid of ~81 mol.% H2O, 14 mol.% CO2, 4 mol.% NaCl ± KCl, and 1 mol.% CH4, which unmixed into a low- and high-salinity immiscible pair. This suggests a more saline parent fluid and a greater degree of fluid unmixing relative to the other occurrences in the eastern Tintina Gold Province. Inclusions trapped in As- and Bi-rich, high-gold grade veins have homogenization temperatures of 300350°C, whereas inclusions found in more Ag- and Pb-rich veins are characterized by temperatures of 250300°C. Fluid inclusion geobarometry suggests hydro-fracturing and gold deposition at 57 km depth. The δ18O values of quartz samples range from 1316 (per mil) and δ34S for sulfides are also consistent between 3.0 and 0, with the exception of some outliers from the Contact Zone of the Pukelman stock that indicate a lower temperature second phase of mineralization. It remains uncertain as to whether the Clear Creek ore fluids were exsolved from magmas at depth or from devolatilization reactions within the contact metamorphic aureoles of the intrusions.
Geochemistry of the Coastal Sonora batholith, Northwestern Mexico
Authors: Valencia-Moreno M , Ruiz J , Ochoa-Landín L , Martínez-Serrano R , Vargas-Navarro P
Published: August 2003

New major- and trace-element and radiogenic Sr and Nd data from granitic rocks help to characterize the geochemical composition of the Coastal Sonora batholith, which represents the westernmost portion of the Laramide Magmatic arc (~8040 Ma) in Mexico. Compared with more inland-located regions of the arc in central and eastern Sonora (Inner Granites), the plutons within the coastal batholith have higher MgO, FeO, and CaO and lower K2O contents, and tend to be more depleted in Nb, U, and to a lesser extent Rb, but relatively enriched in Sr. These rocks display flatter slopes of rare-earth elements, with La abundances around 80 to 200 times chondrite values and smaller but well-developed negative Eu anomalies. Initial 87Sr/86Sr ratios and εNd values from a few studied samples of the Coastal Sonora batholith range from 0.70586 to 0.70679 and from 2.3 to 4.7, respectively. These isotopic signatures allow recognition of a more mantle-related magma source for this batholith as compared with the Inner Granites, which have higher Sr and lower Nd ratios. In a more regional context, the compositions of the Coastal Sonora batholith rocks resemble those of the eastern portion of the Peninsular Ranges batholith to the northwest. Based on our observations, we propose that partial melting of a crust thickened by overlapping periods of Jurassic through Cretaceous arc magmatism along the southwestern edge of the North American continent may account for the geochemical and isotopic characteristics displayed by the Coastal Sonora batholith granitic rocks.
Amphibian assemblages in zero-order basins in the Oregon Coast Range
Authors: Sheridan Chris D , Olson Deanna H
Published: August 2003

Zero-order basins, extending from ridgelines to the initiation of first-order streams, were sampled in the Coast Range of Oregon to (i) characterize spatial distribution patterns of amphibian species and assemblages along longitudinal and lateral gradients, and relative to three geomorphic surfaces (valleys, headmost areas, and slopes); and (ii) develop empirical specieshabitat models. Unmanaged zero-order basins were hotspots for amphibian diversity, with significant differences across geomorphic gradients. Captures of riparian-associated amphibians were higher in valley areas, usually within 2 m of basin center. Upland-associated amphibians were captured two times farther from basin centers than riparian-associated species, but highest densities occurred only 25 m from basin center. The most useful empirical models related captures of individual amphibian species to geomorphic, disturbance, moisture, and overstory variables. Ordination and indicator species analysis characterized geomorphic and other environmental gradients in amphibian assemblages and suggested spatial compression of fluvial habitats and riparian-associated species in zero-order basins, in comparison with downstream areas. Our findings have implications for headwater areas managed to hedge risk to and uncertainty in amphibian persistence, namely in the delineation of zones with species management priority, and in the maintenance of natural fluvial and hillslope disturbance regimes, along with the microhabitat features created by these regimes.
Tree canopy displacement and neighborhood interactions
Authors: Muth Christine C , Bazzaz F A
Published: August 2003

Competitive interactions among plants are largely determined by spatial proximity. However, despite their sessile nature, plants have the ability to avoid neighbors by growing towards areas with high resource availability and reduced competition. Because of this flexibility, tree canopies are rarely centered directly above their stem bases and are often displaced. We sought to determine how a tree's competitive neighborhood influences its canopy position. In a 0.6-ha temperate forest plot, all trees greater than 10 cm DBH (n = 225) were measured for basal area, height, canopy depth, and trunk position. Canopy extent relative to trunk base was determined in eight subcardinal directions, and this information was used to reconstruct canopy size, shape, and position. We found that trees positioned their canopies away from large neighbors, close neighbors, and shade-tolerant neighbors. Neighbor size, expressed as basal area or canopy area, was the best indication of a neighbor's importance in determining target tree canopy position. As neighborhood asymmetry increased, the magnitude of canopy displacement increased, and the precision with which canopies avoided neighbors increased. Flexibility in canopy shape and position appears to reduce competition between neighbors, thereby influencing forest community dynamics.
A comparison of mycangial and phoretic fungi of individual mountain pine beetles
Authors: Six Diana L
Published: August 2003

Two ophiostomatoid fungi, Ophiostoma clavigerum (Robinson-Jeffrey & Davidson) Harrington and Ophiostoma montium (Rumbold) von Arx, are known to be associated with the mycangia of the mountain pine beetle, Dendroctonus ponderosae Hopkins. However, virtually nothing is known regarding the phoretic fungi carried on the external surface of the exoskeleton of this beetle. In this study, I compared the phoretic fungi of individual D. ponderosae with the fungi carried in their mycangia. As many beetles carried ophiostomatoid fungi on the exoskeleton as in the mycangia; however, the species of ophiostomatoid fungus carried phoretically on an individual beetle was not always the same as was carried in its mycangia. Ophiostoma montium was isolated more often from exoskeletal surfaces than from mycangia, while the reverse was true for O. clavigerum. It appears that O. clavigerum is highly adapted for mycangial dissemination, while O. montium is adapted to phoretic as well as mycangial dissemination. Ophiostoma ips (Rumbold) Nannf. was phoretic on two beetles, indicating that cross-contamination with fungi from cohabiting Ips spp. may sometimes occur. Several non-ophiostomatoid fungi were isolated from exoskeletal surfaces, but none consistently so. All non-ophiostomatoid fungi isolated were common saprophytes often found in beetle-killed trees. Yeasts were also common and were isolated more often from the exoskeleton than from mycangia.
Are mixed-species stands more productive than single-species stands: an empirical test of three forest types in British Columbia and Alberta
Authors: Chen H YH , Klinka K , Mathey A -H , Wang X , Varga P , Chourmouzis C
Published: August 2003

Stand volumes were determined for naturally established, even-aged, single- and mixed-species stands involving three combinations of shade-tolerant and shade-intolerant conifers on similar sites: (i) western redcedar  western hemlock (Thuja plicata Donn ex D. Don  Tsuga heterophylla (Raf.) Sarg.), (ii) lodgepole pine  western larch (Pinus contorta Dougl. ex Loud.  Larix occidentalis Nutt.), and (iii) lodgepole pine  black spruce (Pinus contorta  Picea mariana (Mill.) BSP). Stand volume was significantly increased with site index and breast-height age in all three studies. Stand volume was also related to relative stand density in the lodgepole pine  black spruce study. When both species were shade tolerant (hemlockredcedar), stand volume increased linearly with the proportion of hemlock; the mixed-species stands had intermediate volume compared with single-species stands. The combination of two shade-intolerant species (pinelarch) had lower stand volume than that anticipated from single-species stands, implying that one species may inhibiting the growth of the other. Mixtures of shade-intolerant and shade-tolerant species with different growth patterns (sprucepine) may be more productive than single-species stands in specific ecological contexts and developmental stages. The effect of one species on the productivity of another species is tree-species and site specific: at maturity, even-aged, mixed-species coniferous stands are not necessarily more productive than single-species stands.
Perpendicular distance sampling: an alternative method for sampling downed coarse woody debris
Authors: Williams M S , Gove J H
Published: August 2003

Coarse woody debris (CWD) plays an important role in many forest ecosystem processes. In recent years, a number of new methods have been proposed to sample CWD. These methods select individual logs into the sample using some form of unequal probability sampling. One concern with most of these methods is the difficulty in estimating the volume of each log. A new method of sampling CWD that addresses this issue is proposed. This method samples each log with probability proportional to the volume of each piece of CWD. While this method generally has a smaller variance than the existing methods, the primary advantage is that a design-unbiased estimator of CWD volume is achieved without ever actually measuring the volume of any logs. This method, referred to as perpendicular distance sampling (PDS), is compared with three existing sampling techniques for CWD using a simulation study on a series of artificial populations. In every case, the variance of the PDS estimator of CWD volume was smaller than the variance of the competing methods, but the difference in the variance was not large between PDS and two of the competing methods. When estimating the number of pieces of CWD, the variance of the PDS estimator was one of the largest amongst the tested methods. An equally important result is that the variant of line intersect sampling used in this study, where the orientation of the line is the same at all sample points, performed poorly in every situation. This and other problems suggest that the suitability of this sampling technique for estimating CWD is questionable.
Optimizing nitrogen loading ofPicea marianaseedlings during nursery culture
Authors: Salifu K F , Timmer V R
Published: August 2003

Plant growth and nutrient uptake response to increased fertilization can be conceptually described by cur vi linear relationships depicting phases of nutrient deficiency, sufficiency, luxury consumption, and toxicity to rationalize fertilizer prescriptions and improve nutrient diagnosis. We validated this model to determine optimum nitrogen storage of young black spruce (Picea mariana (Mill.) BSP). Container seedlings were supplied with a mixed nitrogenphosphoruspotassium (NPK) fertilizer at rates ranging from 0 to 80 mg N/seedling and reared in a greenhouse for one growing season. Plant growth and nutritional parameters of the plants exhibited classic responses of N deficiency, luxury consumption, and toxicity that were corroborated by vector diagnosis and appeared consistent with the conceptual model. Seedling biomass production was maximized at sufficiency (30 mg N/seedling), whereas N content of tissues peaked at the optimum loading rate (64 mg N/seedling). Toxicity occurred at the 80 mg N/seedling dose rate that increased plant N concentration (5%) but reduced growth (17%) and N content (14%) relative to the optimum level. Plant N content was raised 150% by optimum loading, exemplifying the effectiveness of this practice for building internal N reserves prior to planting. The newly validated model will help refine fertilizer recommendations and nutrient diagnosis for other species or cultural systems.
Relation of headwater macroinvertebrate communities to in-stream and adjacent stand characteristics in managed second-growth forests of the Oregon Coast Range mountains
Authors: Cole Michael B , Russell Kevin R , Mabee Todd J
Published: August 2003

Although headwater streams constitute a significant portion of stream length within watersheds, their aquatic fauna, contributions to regional biodiversity, and responses to forest management have been understudied. Ma cro in ver te brate communities, physical habitat, and water chemistry were sampled from 40 headwater streams in managed forests in the Oregon Coast Range mountains. We characterized functional and structural attributes of ma cro in ver te brate communities in relation to physical, chemical, and biological gradients. Substrate composition, specific conductance, and riparian forest age showed the strongest correlations with resultant ordination patterns in ma cro in ver te brate community composition. Among individual metrics of community structure and composition, total ma cro in ver te brate density and dominance by three taxa showed the strongest correlations with forest age. No community measures were related to densities of torrent salamanders (Rhyacotriton kezeri) or crayfish (Pacifastacus leniusculus), suggesting these potential predators had little influence on overall ma cro in ver te brate community structure. Rare taxa were sampled from several reaches, including Rhyacophila probably viquaea for which little information is available, and an Eobrachycentrus sp., previously known to occur only in the Cascade mountains. Headwater streams within these managed forests of northwestern Oregon appear to be taxa rich, continue to support taxa limited to headwater streams, and harbor taxa about which little is known.
Segmentation of individual tree crowns in colour aerial photographs using region growing supported by fuzzy rules
Authors: Erikson Mats
Published: August 2003

A method based on region growing for segmentation of tree crowns in aerial photographs is presented. By using a decision function, for including a pixel or not, in the spatial domain and in the colour domain simultaneously, the irregular contour of the tree crowns is kept in the segmentation result. Thus, contour information may be subsequently used for tree species classification. A set of possible candidate regions for each tree is evaluated, and the best region, according to a measure, is selected. The method is evaluated on a large sample of high spatial resolution aerial images in central Sweden. Almost 15 ha of natural regenerated boreal forests are included in the image material. On average, the identification of 73% of the tree crowns is in agreement with the corresponding results from the manual delineations. The estimation of the total number of stems from the 30 test images is 93% of the value obtained from the manual count.
Increases in tree growth and nutrient supply still apparent 10 to 13 years following fertilization and vegetation control of salal-dominated cedarhemlock stands on Vancouver Island
Authors: Bennett Jennifer N , Blevins Leandra L , Barker John E , Blevins David P , Prescott Cindy E
Published: August 2003

Cedarhemlock forests on Vancouver Island are primarily nitrogen limited and characterized by an under story dominated by the ericaceous shrub salal (Gaultheria shallon Pursh.). In 1984, an experiment was established on regenerating cedarhemlock forests to determine the effects of nitrogen and phosphorus (N + P) fertilization and vegetation control on conifer growth. It was hypothesized that these treatments would not only stimulate tree growth, but also improve nutrient supply, stand productivity, and site quality. To test this hypothesis, tree height growth, canopy closure, salal biomass, foliar and forest floor N and P concentrations, and seedling growth on forest floor were measured 1013 years after treatment. Both salal control and fertilization increased tree growth and canopy cover, and reduced salal biomass. However, only fertilized plots showed changes in site quality measurable 1013 years following N + P application. Hemlock foliar P concentrations, forest floor total N and P levels, and hemlock height increments were higher in these plots. Forest floors from the fertilized plots also supported greater growth of conifer seedlings. These results suggest that sustained changes to site quality may be achieved with N + P fertilization of cedarhemlock forests.
Paper birch and lodgepole pine root reinforcement in coarse-, medium-, and fine-textured soils
Authors: Campbell K A , Hawkins C DB
Published: August 2003

The increased soil cohesion or reinforcement provided by roots varies among plant species and soil types. This study compared the contribution of paper birch (Betula papyrifera Marsh.) and lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) roots to soil shear resistance in two controlled environment experiments. Roots of paper birch and lodgepole pine trees contributed to a significant increase in soil shear resistance, regardless of soil type. At a shear depth of 0.20 to 0.44 m, paper birch contributed greater reinforcement than lodgepole pine. Both birch and pine provided the most root reinforcement in coarse-textured soil and the least reinforcement in medium-textured silt soil. Soil texture, porosity, and shear strength may have affected root branching of the two species, which in turn may have affected root reinforcement. At less than 1 year of age, paper birch trees planted as plugs can substantially increase soil shear strength compared with lodgepole pine in all soil types.
Evolving Small Neurocontrollers with Self-Organized Compact Encoding
Authors: Boshy Shlomy , Ruppin Eytan
Published: August 2003

This article presents a novel method for the evolution of artificial autonomous agents with small neurocontrollers. It is based on adaptive, self-organized compact genotypic encoding (SOCE) generating the phenotypic synaptic weights of the agent's neurocontroller. SOCE implements a parallel evolutionary search for neurocontroller solutions in a dynamically varying and reduced subspace of the original synaptic space. It leads to the emergence of compact successful neurocontrollers starting from large networks. The method can serve to estimate the network size needed to perform a given task, and to delineate the relative importance of the neurons composing the agent's controller network.
Irigaray and the Culture of Narcissism
Authors: Whitford Margaret
Published: August 2003

This article recontextualizes Irigaray with reference to post-Freudian psychoanalytic theories of narcissism, and argues that a persistent theme in her work has been the diagnosis of the narcissism of Western culture. It indicates that one of the possible sources (other than Lacan) for her diagnosis of Western culture is the work of Béla Grunberger. It also argues that it is possible to make connections between Irigaray's critique of Western civilization and other related critiques. The second part of the article sketches a brief account of the Kleinian and post-Kleinian concept of projective identification, and argues that reinterpreting Irigaray in the light of this concept can help to shed more light on her account of the significance of the maternal container.
Redirection in Georgia
Authors: Douglas James W.
Published: August 2003

The budgeting reform literature is replete with examples of reforms such as performance budgeting, program budgeting, and zero-base budgeting that have failed to achieve their stated goals. This article analyzes a new budgetary reform that has been introduced in the state of Georgia, which appears to be accomplishing what its proponents have pronounced. This reform is known as redirection. The article defines redirection, explains how it works, and shows that redirection has enabled budget actors to reset budgetary priorities and reduce agency acquisitiveness, at least in its first 2 years in operation.
From the Search for Universal Correlations to the Institutional Structuring of Economic Organization and Change: The Development and Future of Organization Studies
Authors: Whitley Richard
Published: August 2003

Organization studies became institutionalized as a distinct research field in North America in the 1960s as leading universities expanded to include the new behavioural and management sciences. In keeping with the prevailing image of science, it adopted an empiricist epistemology and an atomistic ontology that portrayed formal organizations as isolated, reactive hierarchies adapting to market selection mechanisms. The further expansion of higher education in North America and Europe in the 1970s and 1980s, especially in business and management studies, together with the failure of the logical empiricist research programme in the Anglo-Saxon philosophy of science and the decline of Fordism, encouraged considerable fragmentation of organization studies around rival frameworks. Additionally, the success of East Asian firms in many international markets and continued divergence of many European forms of capitalism from the US norm led to increasing interest in the role of institutional frameworks in structuring and reproducing competing forms of economic organization. This involved a radical reconceptualization of both the nature of formal organizations and their environments, which complemented developments in evolutionary and institutional economics. As a result, organizations have come to be seen as key mediating collectivities between national and international political-economic institutions and economic outcomes in different kinds of market economy.
No Sense of an Ending:
Authors: Grounds Adrian , Jamieson Ruth
Published: August 2003

This article describes an interview-based study of the effects of long-term imprisonment upon 18 Republican ex-prisoners and their families. The interviews followed a biographical, narrative format, drawing from experience of psychiatric assessments of released long-term prisoners. Interpretation of the material was influenced by the sociological literature on imprisonment effects and war trauma. The ex-prisoners had spent an average of 11 years in custody. They described complex experiences of loss, psychological change and social adjustment difficulties, together with persistent barriers to social integration, particularly in the area of employment. A decade after release some still had vivid difficulties in coming to terms with the losses of the past and finding purpose for the future. There were parallels between the experiences of this group and those of war veterans returning home. There is insufficient recognition of these phenomena in previous research on the psychological effects of imprisonment.
Making Meaning
Authors: Krepapa Areti , Berthon Pierre
Published: August 2003

A major task for organizations is to make interpretations. Despite, however, the growing concern of the business and academic community over organizational weaknesses in interpreting and acting upon the contemporary market information tsunami, the process of interpretation has not yet been explicitly addressed in the marketing literature. To this end, this article identifies interpretation of information as the central phenomenon of the market learning process and explicates its nature. The authors address the issue of collective interpretation by introducing the concept of interpretive diversity and modelling four interpretive modes. These modes are then linked through formal propositions to the key market learning processes of information acquisition and marketing action. The implications for marketing thought and practice are discussed.
Combined seismic inversion and gravity modeling of a shallow anomaly in the southern Barents Sea
Authors: Ursin Bjørn , Bauer Christian , Zhao Huasheng , Fichler Christine
Published: August 2003

A combination of prestack elastic inversion with gravity modeling has been applied to a shallow seismic anomaly in the southern Barents Sea. The anomaly is crosscutting dipping layers of late Paleocene age. Earlier seismic interpretations indicate a possible origin in gas‐hydrated sediments trapping underlying free gas. Our interpretation includes seismic inversion of a seismic model which consists of a stack of isotropic, homogeneous, and anelastic layers. The unknown parameters are the P‐ and S‐wave velocities, density, and thickness for each layer. As densities are poorly determined by this method, we included gravity modeling, which improved the density estimates. The resulting parameters have been integrated by rock physics calculations and the knowledge of typical attributes of gas hydrate occurrences. The top of the seismic anomaly is interpreted as a reflection from the base of a gas‐hydrated sediment trapping underlying free gas. The base of the anomaly is the gas‐water contact, which deviates from a flat spot due to capillary pressure differences related to lithology and the generation process of gas hydrate. The estimated density has been interpreted together with well results and indicates a significant amount of gas filling the pore volume.