bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of silt and very fine sand dynamics in Atlantic salmon (Salmo salar) redds on embryo hatching success
Authors: Levasseur Mylène , Bergeron Normand E , Lapointe Michel F , Bérubé Francis
Published: July 2006

We conducted a 2-year field experiment examining the survival to hatching of Atlantic salmon (Salmo salar) in relation to the seasonal and spatial variations of silt and very fine sand (SVFS; <0.125 mm) content within a large set of artificial redds at two spawning sites of the Sainte-Marguerite River, Quebec, Canada. Each artificial redd consisted of an infiltration cube (30 cm × 30 cm × 20 cm) buried in a morpho-sedimentological unit resembling a salmon redd. One hundred fertilized Atlantic salmon eggs were inserted in a number of infiltration cubes during redd construction. The results indicate no significant relation between survival to hatching in spring and values of the sand index or total percent fine sediment <2 mm in redds at that time. However, the proportion of SVFS in the redds explained 83% of the variation in embryo survival, with a threshold at approximately 0.2% SVFS, above which survival dropped sharply below 50%. Infiltration of these very fine fractions mostly occurred under ice cover, during the low-flow winter period. However, during the spring flood period, infiltration-flushing patterns varied spatially and reflected spatial differences in local intensity of bed-load transport and fine sediment availability.
Does eel metamorphosis cause a breakdown in the tenets of otolith applications? A case study using the speckled worm eel (Myrophis punctatus, Ophichthidae)
Authors: Powles Perce M , Hare Jonathan A , Laban Elisabeth H , Warlen Stanley M
Published: July 2006

Several basic tenets of otolith research have been questioned recently with regard to eel metamorphosis. Specifically, some researchers have suggested that otolith increment formation is not daily, and otolith material may be resorped during metamorphosis. We conducted a rearing experiment to test the hypothesis that increment formation is daily and that the otolith continues to grow during eel metamorphosis. We marked the otoliths of wild-caught Myrophis punctatus leptocephali and reared these fish through metamorphosis. Metamorphosis was characterized by a decreasing standard length, pre-anal length, and body depth accompanied by an increase in pigmentation and a change in behavior. Increment formation was daily or near-daily through metamorphosis, and the otolith continued to grow during metamorphosis. Thus, the basic tenets of otolith application apply to eel metamorphosis, and non-daily ring deposition and resorption should not be used as explanations for otolith characteristics of eels (e.g., back-calculated hatch dates) unless demonstrated experimentally.
Mapping seabed assemblages using comparative top-down and bottom-up classification approaches
Authors: Eastwood Paul D , Souissi Sami , Rogers Stuart I , Coggan Roger A , Brown Craig J
Published: July 2006

Acoustic technologies yield many benefits for mapping the physical structure of seabed environments but are not ideally suited to classifying associated biological assemblages. We tested this assumption using benthic infauna data collected off the south coast of England by applying top-down (supervised) and bottom-up (unsupervised) classification approaches. The top-down approach was based on an a priori acoustic classification of the seabed followed by characterization of the acoustic regions using ground-truth biological samples. By contrast, measures of similarity between the ground-truth infaunal community data formed the basis of the bottom-up approach to assemblage classification. For both approaches, individual assemblages were mapped by first computing Bayesian conditional probabilities for ground-truth stations to estimate the probability of each station belonging to an assemblage. Assemblage distributions were then interpolated over a regular grid and characterized using an indicator value index. While the two methods of classification yielded assemblages and output maps that were broadly comparable, the bottom-up approach arrived at a slightly better defined set of biological assemblages. This suggests that acoustically derived seabed data are not ideally suited to class ifying biological assemblages over unconsolidated sediments, despite offering considerable advantages in providing rapid and low-cost assessments of seabed physical structure.
Changes in spring phytoplankton communities and nutrient dynamics in the eastern basin of Lake Erie since the invasion of Dreissena spp.
Authors: Barbiero Richard P , Rockwell David C , Warren Glenn J , Tuchman Marc L
Published: July 2006

Distinct changes have occurred in the size and composition of the spring phytoplankton community in the eastern basin of Lake Erie following the introduction of Dreissena. Since 1996, total phytoplankton biovolume has decreased to approximately 20% of pre-Dreissena levels, whereas postinvasion concentrations of spring soluble nutrients, particularly silica, have been substantially elevated compared with earlier years. Spring dominance has shifted from a mix of pennate and large centric diatoms and pyrrophytes to three centric diatoms with high silica requirements: Aulacoseira islandica, Stephanodiscus hantzschii, and Stephanodiscus parvus, and the overall diversity and species richness of the spring phytoplankton community has declined significantly. In addition, current April silica concentrations are approximately twice as high as historical (i.e., 1960s–1980s) winter maxima, indicating that the silica content of the lake has increased since the dreissenid invasion. These results suggest that the severe silica depletion caused by increased anthropogenic inputs of nutrients during the last century has been mitigated through a decrease in diatom production, most likely brought about by dreissenid grazing.
Impact-recovery patterns of water quality in temporary wetlands after fire retardant pollution
Authors: Angeler David G , Moreno José M
Published: July 2006

Fire retardants, which are used in wildland fire prevention and extinguishing operations, can cause eutrophi cation of surface waters. We measured water quality in artificially constructed outdoor ponds over three hydrological cycles to determine impact-recovery trajectories in retardant-contaminated, temporary wetlands. We used a multiple beforeafter controlimpact (MBACI) design to determine the effects of application rates that are used in grasslands (1 L·m2) and scrublands (3 L·m2). Retardant application caused a significant increase in the trophic status of the ponds in the postcontamination period (second and third hydrological cycle) relative to the precontamination period (first hydrological cycle). The retardant clearly affected nutrients and indirectly affected chlorophyll a, pH, dissolved oxygen, and Secchi transparency, resulting in a shift from clear water to turbid water stable states. Univariate analyses showed that water quality variables showed distinct recovery trajectories, as influenced by natural, seasonal changes (chiefly water level fluctuations). Nonmetric, multidimensional scaling analyses suggest that water quality did not return to precontamination levels after two hydrological cycles in the retardant-treated ponds. Water quality affected by retardant contamination appeared to maintain wetlands in hysteresis for at least two hydrological cycles and prevented them from returning to the clear water, submerged macrophyte-dominated state.
Migration of viscous non-aqueous phase liquids (NAPLs) in alluvium, Fraser River lowlands, British Columbia
Authors: Jackson Richard E , Dwarakanath Varadarajan , Ewing John E , Avis John
Published: July 2006

Coal tar, creosote, and similar viscous non-aqueous phase liquids (NAPLs) behave in alluvial soils in a manner significantly different from that of less viscous NAPLs, such as gasoline and chlorinated solvents. Their unique behavior is due to the interaction of their physicalchemical parameters: a density often greater than water, a viscosity significantly greater than water, and an interfacial tension that yields a positive initial spreading coefficient at airwaterNAPL interfaces. This results in slow, creeping flow that causes long-term contamination at former manufactured gas plants and wood-preserving sites and of their adjacent surface waters. Multiphase simulations of this creeping flow are shown for a site along the lower Fraser River near Vancouver, British Columbia, and the long-term consequences of the migration of viscous NAPLs in alluvium are discussed from the perspective of site characterization and brownfields redevelopment.Key words: creosote, coal tar, multiphase simulation, brownfields, NAPL.
Limitations of the theorem of corresponding states in active pressure problems
Authors: Silvestri Vincenzo
Published: July 2006

This paper analyzes the application of the theorem of corresponding states or the correspondence rule, as found in a number of advanced soil mechanics textbooks, and shows that it results in approximate solutions to limit-state problems. The limitations of the rule are made apparent by applying it to the determination of active pressures exerted on vertical retaining walls by cohesivefrictional backfills with inclined ground surfaces. A correct derivation of the correspondence rule is obtained for this case. An example is given that illustrates the inadequacy of this rule when boundary conditions are not properly accounted for in the analysis.Key words: theorem of corresponding states, active pressure, vertical retaining wall, inclined ground surface, cohesivefrictional backfill.
Shear strength characteristics of an unsaturated expansive clay
Authors: Zhan Tony LT , Ng Charles WW
Published: July 2006

The shear strength characteristics of an expansive clay from China were studied by performing suction-controlled direct shear tests on both natural and compacted specimens. The tested soil was a silty clay with intermediate plasticity and medium expansion potential. A modified direct shear apparatus with a newly developed water volume indicator was used for this laboratory study. The experimental results clearly show that the dilatancy of the expansive clay increases with an increase in the applied suction for both the natural and compacted specimens. Matric suction contributes to the shear strength of the expansive clay via two different mechanisms: the contribution of capillary force to interparticle normal stress, and the effect of suction on soil dilatancy. As a result of the second mechanism, the contribution of suction to peak shear strength for the clay is more significant than that to post-failure shear strength, particularly at a high suction range. The contribution of suction to post-failure shear strength for the natural specimen is basically consistent with that for the compacted specimen. The higher peak shear strength and dilatancy for the natural specimen are related to the cementation effect of the iron and manganese oxides. The contribution of suction to shear strength for the compacted expansive clay is more significant than that for a compacted kaolin at suctions less than 100 kPa.Key words: expansive clay, matric suction, shear strength, dilatancy, direct shear test, water content.
Comparison study of parameter estimation techniques for rock failure criterion models
Authors: Das Sarat Kumar , Basudhar Prabir Kumar
Published: July 2006

This paper presents a comparative study of parameter estimation of rock failure criteria using different statistical methods, such as the least squares, least median squares, and reweighted least squares. The Mises–Schleicher and Drucker–Prager unified (MSDPu) failure criterion, a nonlinear polyaxial failure criterion suitable for different rock strength data, has been considered for this study. The procedure for determining model parameters from scattered data using the least median squares method is presented, and the methods of identifying the scattered data are discussed. The use of the reweighted least squares method for improving statistical performance of model parameter estimation from scattered data is presented. Using the variable transformation technique, the parameter estimation problem has been formulated as an unconstrained minimization problem. Here, both traditional nonlinear programming techniques and recently developed evolutionary optimization algorithms have been employed, and a comparative study of their relative efficacy is presented. Of several traditional nonlinear unconstrained minimization techniques, only the Hooke–Jeeves method could be used to find the optimum value, but its robustness is much lower than that of evolutionary algorithms. Evolutionary algorithms can be applied to find the optimal solution for cases with a high degree of robustness.Key words: rock mechanics, failure criterion, parameter determination, least median squares, evolutionary optimization.
One-electron oxidation of methionine peptides — Stability of the three-electron S—N(amide) bond
Authors: Brunelle Patrick , Schöneich Christian , Rauk Arvi
Published: July 2006

The possibility of sulfur–nitrogen (S—N) three-electron bond formation in a one-electron oxidized methionine peptide model was investigated computationally following the detection of such species in pulse radiolysis experiments (C. Schöneich, D. Pogocki, G.L. Hug, and K. Bobrowski. J. Am. Chem. Soc. 125, 13700 (2003)). Geometry optimiza tions were carried out at the B3LYP/6-31G(d) level of theory. Relative free energies in aqueous solution at pH 7 were predicted for all intermediates with enthalpy evaluations at the CCSD(T)/6-31+G(d′) level and free energies of solvation predicted using a continuum model (CPCM). Both the initial oxidation product and the intermediate formed at higher pH were identified as cyclic S—N bonded species in which the intramolecular three-electron interaction is between the S atom and the π orbital of the amide group. TD-B3LYP calculations of the UV spectra support the assignments. A mechanism for the conversion to the most stable α-C-centered radical is proposed. The mechanism involves a novel deprotonation–reprotonation via an intermediate backbone-delocalized radical anion.Key words: methionine oxidation, three-electron bonding, S—N bonding, B3LYP.
Efficient stabilization of oligonucleotide duplexes through terpyridine metal complexes
Authors: Freville Fabrice , Pierre Nathalie , Moreau Serge
Published: July 2006

A large increase in the melting temperature of complementary oligonucleotides was obtained through the conjugation of terpyridine ligands at their nearby 5′ or 3′ ends and the addition of stoichiometric amounts of various transition metals. We describe here a short efficient synthetic route for the conjugation of terpyridine moieties and report new data on the stabilizing contribution of metal-assisted hybridization of oligonucleotides through UV-monitored melting temperature experiments.Key words: oligonucleotides, metal complexes, terpyridine.
Novel synthesis of 2-naphthol Mannich bases and their NMR behaviour
Authors: Jha Amitabh , Paul Nawal K , Trikha Smriti , Cameron T Stanley
Published: July 2006

A novel two-step procedure involving the formation of 1-arylidene-2-tetralones from 2-tetralone and subsequent Michael addition of a cyclic secondary amine on the alkenone followed by in situ aerial oxidation was developed to produce 2-naphthol Mannich bases. A simple microwave-assisted one-pot synthesis of 2-naphthol Mannich bases was also carried out under solvent-free conditions from 2-naphthol and corresponding aldehydes and amines in the presence of p-toluenesulfonic acid. The compounds of this series displayed interesting NMR behaviour. Extensive variable-temperature NMR investigations, including HSQC experiments, are herein reported. NMR results on the conformation in solution phase were found to be consistent with the X-ray crystal structure in the solid state.Key words: Mannich bases, microwave-assisted Mannich reaction, temperature-variable NMR spectroscopy, NMR dynamics, X-ray crystallography.
NMR study of hydrogen bonding in methanol  carbon tetrachloride solutions
Authors: Deng J Q , Lipson R H
Published: July 2006

The nuclear magnetic resonance (NMR) frequencies of the hydroxyl protons of methanol clusters in carbon tetrachloride were measured as a function of concentration between 245.4 and 320.2 K. The size of the methanol cluster (n) and the enthalpy and entropy of methanol self-association were obtained from nonlinear least-squares fittings to a model that assumed that only one dominant cluster was in equilibrium with the monomer at each temperature. The chemical shift measurements at 273 and 299.1 K fit best to theoretical curves calculated for a monomertetramer equilibrium. However, at higher and lower temperatures, the analyses indicate that the most dominant clusters are smaller and larger, respectively.Key words: alcohol liquid solutions, structure, hydrogen bonding, thermodynamics of self-association, nuclear magnetic resonance.
The synthesis of butene glycol ethers with aluminium triflate
Authors: Terblans Yvette M , Huyser Michelle , Young Desmond A , Green Michael J
Published: July 2006

The use of aluminium triflate as a ring-opening catalyst for butene oxide (BuO) was evaluated in the presence of different alcohols such as methanol, ethanol, n-propanol, n-butanol, 2-propanol, 2-methyl-1-propanol, and 2-methyl-2-propanol. The reaction with methanol was studied kinetically by varying the temperature, catalyst concentration, and methanol  butene oxide molar ratio. These reactions yielded two major products (2-methoxy-1-butanol and 1-methoxy-2-butanol) in a approximate ratio of 1:1. It was noted that at low catalyst concentrations (<5 ppm), low temperatures (<90 °C), and a MeOHBuO molar ratio of 8:1, the selectivity of the reaction could be kinetically manipulated to shift the product ratio towards 1-methoxy-2-butanol, the α-alkoxyalcohol. This result was confirmed by an experimental design program. Statistical calculations using the data from the experimental design identified a feasible region in which reactions with methanol could be carried out, which would lead to slightly higher selectivities to 1-methoxy-2-butanol. This region shows that the methanol  butene oxide ratio should be 8:1, the temperature between 80 and 85 °C, and the catalyst concentration between 3.9 and 5 ppm. These reaction conditions were used to carry out a test reaction with methanol and an extended series of alcohols. All the alcohols, except for 2-methyl-2-propanol, reacted with butene oxide under these conditions, with the selectivity to the α-alkoxyalcohol higher than to the β-alkoxyalcohol. To obtain a ring-opening reaction with 2-methyl-2-propanol, it was found that a higher catalyst concentration (approximately 10 ppm) and a lower alcohol  butene oxide ratio (6:1) at a temperature of 80 °C were necessary. This reaction led to a mixture of 1-tert-butoxy-2-butanol and 2-tert-butoxy-1-butanol with the selectivity to the α-alkoxyalcohol being somewhat higher because of the steric influence of the bulky tert-butoxy group.Key words: aluminium triflate, alcohols, butene oxide, ring opening, α-alkoxyalcohol, β-alkoxyalcohol.
Cucurbit[7]uril host-guest complexes with cationic bis(4,5-dihydro-1H-imidazol-2-yl) guests in aqueous solution
Authors: Hettiarachchi D Saroja N , Macartney Donal H
Published: July 2006

The host–guest interactions between cucurbit[7]uril and a series of novel cationic bis(4,5-dihydro-1H-imidazol-2-yl)arene and 1-(4,5-dihydro-1H-imidazol-2-yl)- and 1,3-bis(4,5-dihydro-1H-imidazol-2-yl)-adamantane guests have been investigated in aqueous solution using UV–vis and NMR spectroscopy, and electrospray mass spectrometry. With the exception of the 1,3-bis(4,5-dihydro-1H-imidazol-2-yl)adamantane (which binds externally to the CB[7]), these guests form very stable inclusion complexes with slow exchange on the 1H NMR timescale. The direction and magnitude of the complexation-induced shifts (CIS) in the proton resonances of the guests are indicative of the residence of the hydrophobic core of the guest within the CB[7] cavity and the charged 4,5-dihydro-1H-imidazol-2-yl units outside the cavity adjacent to the carbonyl-lined portals of the host. The CIS values and the inclusion stability constants have been correlated with the nature of the guest core and with the distance between the charges on the terminal 4,5-dihydro-1H-imidazol-2-yl rings.Key words: cucurbit[7]uril, host–guest complex, dihydroimidazolyl, inclusion stability constants.
A forest-level genetic algorithm based control system for generating stand-specific log demand distributions
Authors: Kivinen Veli-Pekka
Published: July 2006

This study was established to test whether the fit between the overall log demand distributions required by mills and the cumulative log output distributions could be improved by localizing the demand matrices controlling the bucking-to-order process on modern cut-to-length harvesters. Fifteen mature Norway spruce (Picea abies (L.) Karst.) stands were cut with a bucking simulator under the control of both the stand-specific and uncontrolled reference demand matrices. The test simulations involved three Norway spruce log products: sawlogs, veneer logs, and pulpwood logs. The stand-specific demand matrices for these products were generated in parallel using a genetic algorithm (GA) based search system initiated by the taper of each tree to be harvested and the overall demand and price matrices of each log product. The GA system was run with both the real stem data (i.e., stem profiles recorded by harvester) and the stem data compiled from preharvest forest inventory data. The reference matrices were the overall demand matrices adopted from two Finnish sawmilling companies. The test results showed that compared to the uncontrolled reference matrices the GA-controlled demand matrices produced a 22%103% higher total fit between the overall log demand distributions and the cumulative log output distributions at the forest level.
Edge-correction needs in estimating indices of spatial forest structure
Authors: Pommerening Arne , Stoyan Dietrich
Published: July 2006

Indices quantifying spatial forest structure are frequently used to monitor spatial aspects of tree attributes including biodiversity in research plots of limited size. The treatment of edge trees, which are close to the plot boundaries, can affect the estimation of such indices that include neighbour effects, since some of their neighbours are likely to fall outside the plot. This paper investigates whether and under what circumstances edge-correction methods are necessary and evaluates the performance of six different approaches: no edge correction, translation, reflection, buffer zone, and two new nearest-neighbour methods. The performance of edge-correction methods depends strongly on the algorithmic structure of the indices and the spatial pattern of tree positions involved. Some edge-correction methods introduce more error than ignoring edge bias altogether. For indices accounting for the diversity of tree positions and especially for those computing angles, translation or buffer zone methods reduce the estimation error regardless of the sample size. The use of the reflection method is associated with large bias values. One of the new nearest-neighbour edge-correction methods proves to be capable of reducing the bias considerably. The results confirm the need for sufficiently large monitoring plots to avoid bias from edge effects. Where this is impossible, neighbours beyond the plot boundary need to be included in the survey, thus providing unbiased estimates but at the cost of extra measurements. Sensitivity analysis is required for newly introduced indices prior to their first application.
Eliminating the effect of overlapping crowns from aerial inventory estimates
Authors: Mehtätalo Lauri
Published: July 2006

When a forest stand is inventoried from aerial photographs or with the use of laser scanners, only those trees that are not covered by a crown of a taller tree can be observed. This means that the probability of a tree being observable from the air depends on its relative height among the trees in the stand and on the crown areas of the taller trees. This study derives a mathematical formula for the probability of a tree being observable from the air according to certain assumptions about the censoring process in a forest stand where trees are randomly located without spatial autocorrelation in tree size. After presenting this formula, different approaches are proposed for the correction of the censoring effect upon the observed distribution of crown areas. The methods could change the aim of individual-tree recognition from finding all trees of the stand to finding a set of trees for which the stated assumptions about the censoring process are valid as far as possible. The methods performed well in a demonstration with simulated, error-free data sets, for which all stated assumptions were valid.
Geographic and seasonal variation in cold hardiness of whitebark pine
Authors: Bower Andrew D , Aitken Sally N
Published: July 2006

Artificial freeze-testing utilizing the electrolyte-leakage method was used to test the cold hardiness of 2-year-old whitebark pine (Pinus albicaulis Engelm.) seedlings growing in a common garden. Testing across all seasons was used to determine the annual pattern of cold hardiness, and more intensive sampling in the fall and spring was used to assess genetic variation in cold injury among geographic regions spanning the range of the species. Mean hardiness varied widely from –9 °C in early summer to below –70 °C in the winter. Trees from interior and northern regions were the most hardy in the fall, while trees from California were the least hardy. Geographic patterns of hardiness in the spring were reversed. Significant differences in cold injury among regions were detected on all dates except during the winter. Heritability was low to moderate for both the spring (h2 = 0.18) and the fall (h2 = 0.28), and genetic correlation was weak (rA = 0.18). Only spring cold injury was genetically correlated with date of needle flush (rA = 0.34). Mean cold injury in the fall was most closely correlated with mean temperature of the coldest month in the parental environment (r = 0.81). Whitebark pine is well adapted to the low temperatures of the harsh environments where it is found; however, regional variation indicates that moving seed for restoration purposes from areas with higher winter temperatures to colder environments may increase the chance of fall cold injury.
Multicentury history of western spruce budworm outbreaks in interior Douglas-fir forests near Kamloops, British Columbia
Authors: Campbell Rochelle , Smith Dan J , Arsenault André
Published: July 2006

Western spruce budworm (Choristoneura occidentalis Freeman) is a native defoliator of forests in the interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) forests of British Columbia, Canada. Dendrochronological techniques and the software program OUTBREAK were used to reconstruct a defoliation history of Douglas-fir for 19 forest sites near Kamloops in central British Columbia. By comparing the radial-growth response of ponderosa pine (Pinus ponderosa Dougl. ex P. Laws. & C. Laws.) with that of Douglas-fir growing in nearby but separate stands, eight western spruce budworm outbreaks over the past 300 years were distinguished. Although there is considerable variation in the timing and duration of these western spruce budworm events at the stand level, synchronous outbreaks have occurred in approximately 30- to 43-year cycles. Spectral analyses of a composite time series from all stands showed similar and consistent intervals between outbreaks. Climatic variation appears to have been important to budworm outbreaks in the 20th century. Notable outbreaks tended to occur during years with average spring air temperatures following winters with less than average precipitation. Based on this finding, it is proposed that with high over-winter survival rates and a longer growing season, the duration of outbreaks may increase in the future.
Regrowth of understory epiphytic bryophytes 10 years after simulated commercial moss harvest
Authors: Peck JeriLynn E
Published: July 2006

Commercial moss harvest is the predominant disturbance for understory epiphytic bryophyte mats in the Pacific Northwest, yet the rate and dynamics of regrowth of this nontimber forest product are unknown. The first long-term evaluation of cover and species richness regrowth following simulated commercial moss harvest from understory vine maple (Acer circinatum Pursh) shrub stems is reported. Stems harvested of moss on six sites in the Oregon Coast Range in 1994 were examined for species composition and relative abundance of regrowth over the course of a decade. Percent cover increased 5.1%/year, averaging only 51% cover in year 10. Forty percent of the total cover in year 10 was attributable to encroachment from adjacent undisturbed mats and 14% to reestablished litterfall. Shortly after harvest, many taxa established on the newly available habitat, such that species richness surpassed preharvest levels by year 3. In the absence of competitive exclusion even by year 10, species richness continued to exceed preharvest levels by two taxa. Vegetative cover regrowth may require 20 years and volume recovery even longer. Commercial moss harvest should be managed on rotations of several decades, and patchy harvest methods should be encouraged over complete strip harvesting to ensure moss regeneration and promote bryophyte diversity.
Measuring the decay resistance of Scots pine heartwood indirectly by the Folin-Ciocalteu assay
Authors: Harju Anni M , Venäläinen Martti
Published: July 2006

To exploit the variation in the natural durability of heartwood timber, screening of a large number of trees or timber is necessary. We suggest that the concentration of total phenolics, measured by the Folin–Ciocalteu (FC) assay, can be used to supplement or even replace in vitro decay tests for screening the variation in the resistance of Scots pine (Pinus sylvestris L.) heartwood timber against the brown-rot fungus Coniophora puteana (Schum. ex Fr.). We screened the juvenile heartwood of 520 Scots pine trees with the FC assay. Samples from 40 trees, with total phenolics concentrations ranging from 1.9 to 21.7 mg tannic acid equivalents (TAE)/g of heartwood, were subjected to an in vitro decay test. The correlation (r) between the total phenolics concentration and mass loss was –0.82 (p < 0.001) in the 7 week long decay test. The relationship was expressed with a linear regression equation: mass loss (mg/g) = 487 – 25 × concentration of total phenolics (mg TAE/g). This strong relationship could be exploited by replacing the decay test with the FC assay to more rapidly assess the durability of wood products.
Evolution of the Size and Functional Areas of the Human Brain
Authors: Schoenemann P. Thomas
Published: July 2006

The human brain is one of the most intricate, complicated, and impressive organs ever to have evolved. Understanding its evolution requires integrating knowledge from a variety of disciplines in the natural and social sciences. Four areas of research are particularly important to this endeavor. First, we need to understand basic principles of brain evolution that appear to operate across broad classes of organisms. Second, we need to understand the ways in which human brains differ from the brains of our closest living relatives. Third, clues from the fossil record may allow us to outline the manner in which these differences evolved. Finally, studies of brain structure/function relationships are critical for us to make behavioral sense of the evolutionary changes that occurred. This review highlights important questions and work in each of these areas.
Food and Globalization
Authors: Phillips Lynne
Published: July 2006

This review takes two key approaches for exploring the theme of food and globalization: first, how food has been mobilized as a commodity in global production and trade systems and governed through global institutions; and second, how the idea of globalization has been nourished through food, particularly with the mobility of people and of ideas about cuisine and nutrition. Stark global inequalities are also noted, and the review calls for attention to policy-based research and to the analytical connections between governance, food politics, and food citizenship in future studies.
Persistent Hunger: Perspectives on Vulnerability, Famine, and Food Security in Sub-Saharan Africa
Authors: Baro Mamadou , Deubel Tara F.
Published: July 2006

This review examines the persistence of chronic hunger in Sub-Saharan Africa in the twenty-first century and reviews dominant famine theories, concepts of vulnerability, and household livelihood security and responses to recent food crises in the region. The authors argue that famine occurrences are linked to historical and contemporary socioeconomic processes that have increased over time the vulnerability of African households to hunger and reduced their resilience to environmental and economic shocks, political conflict, and the rapid spread of HIV/AIDS. Approaches to famine need to move away from the “emergency relief” framework to better address the underlying conditions that make food shortages endemic. Future food security for Africa requires an integrated long-term response to household vulnerability on the part of African governments, civil society, and international partners by incorporating new technologies, local expertise, and active involvement of African communities living with the realities of recurrent famine.
Anthropology and International Law
Authors: Merry Sally Engle
Published: July 2006

International law, including human rights law, has expanded enormously in the past century. A growing body of anthropological research is investigating its principles and practices. Contemporary international law covers war and the treatment of combatants and noncombatants in wartime; international peace and security; the peaceful settlement of disputes; economic arrangements and trade agreements; the regulation of the global commons such as space, polar regions, and the oceans; environmental issues; the law of the sea; and human rights. This review demonstrates how anthropological theory helps social scientists, activists, and lawyers understand how international law is produced and how it works. It also shows the value of ethnographic studies of specific sites within the complex array of norms, principles, and institutions that constitute international law and legal regulation. These range from high-level commercial dispute settlement systems to grassroots human rights organizations around the world.
On the Resilience of Anthropological Archaeology
Authors: Flannery Kent V.
Published: July 2006

I have now lived through eras when anthropological archaeology was (a) mainly culture history; (b) part of four-field anthropology; (c) hypothetico-deductive science; (d) under attack from postmodernism, postcolonialism, and feminism; and (e) saved from extinction by its own resilience. In this never-before-published interview, I reveal its likely future direction. (Drum roll, please.)
The Maya Codices
Authors: Vail Gabrielle
Published: July 2006

Research over the past decade has significantly advanced our understanding of the prehispanic Maya codices, both in terms of their content (i.e., hieroglyphic texts, calendrical structure, and iconography) as well as the physical documents themselves (where and when they were painted, and by whom). Recent avenues of exploration include a new emphasis on linguistic and textual analyses; novel methodologies for interpreting calendrical structure; and comparisons with other manuscript traditions, in particular those from highland central Mexico. As a result of these studies, researchers have found that some codical almanacs functioned as real-time instruments to document important astronomical events; others were used to schedule rituals as part of the 52-year calendar that guided civic and religious life in Mesoamerica during the Late Postclassic period (circa A.D. 1250 to 1520). Evidence of connections with central Mexico, documented in terms of interchange among codical scribes, suggests the need for a more thorough exploration of Maya–highland Mexican interaction during this time period.
Ecological Effects of Invasive Arthropod Generalist Predators
Authors: Snyder William E. , Evans Edward W.
Published: July 2006

Arthropod generalist predators (AGP) are widespread and abundant in both aquatic and terrestrial ecosystems. They feed upon herbivores, detritivores, and predators, and also on plant material and detritus. In turn, AGP serve as prey for larger predators. Several prominent AGP have become invasive when moved by humans beyond their native range. With complex trophic roles, AGP have diverse effects on other species in their introduced ranges. The invaders displace similar native species, primarily through competition, intraguild predation, transmission of disease, and escape from predation and/or parasites. Invasive AGP often reach higher densities and/or biomass than the native predators they replace, sometimes strengthening herbivore regulation when invasive AGP feed on key herbivores, but sometimes weakening herbivore suppression when they eat key predators. The complexity and unpredictability of ecological effects of invasive AGP underscores the high risk of adverse consequences of intentional introductions of these species (e.g., for biological control or aquaculture).
Unifying and Testing Models of Sexual Selection
Authors: Kokko Hanna , Jennions Michael D. , Brooks Robert
Published: July 2006

Sexual reproduction is associated with the evolution of anisogamy and sperm-producing males and egg-laying females. The ensuing competition for mates has led to sexual selection and coevolution of the sexes. Mathematical models are extensively used to test the plausibility of different complicated scenarios for the evolution of sexual traits. Unfortunately, the diversity of models is now itself equally bewildering. Here we clarify some of the current debate by reviewing evolutionary explanations for the relationship between anisogamy, potential reproductive rates, parental care, sex roles, and mate choice. We review the benefits females might gain by mating with certain males rather than others. We also consider other forms of selection that can make females mate nonrandomly. One way empiricists can contribute to resolving theoretical disputes is to quantify the cost of expressing mating biases in the appropriate life-history currency.
Regulation of Imaginal Disc Growth by Tumor-Suppressor Genes in Drosophila
Authors: Hariharan Iswar K. , Bilder David
Published: July 2006

Inactivating mutations in the Drosophila tumor-suppressor genes result in tissue overgrowth. This can occur because the mutant tissue either grows faster than wild-type tissue and/or continues to grow beyond a time when wild-type tissue stops growing. There are three general classes of tumor-suppressor genes that regulate the growth of imaginal disc epithelia. Mutations in the hyperplastic tumor-suppressor genes result in increased cell proliferation but do not disrupt normal tissue architecture. These genes include pten, Tsc1, Tsc2, and components of the hippo/salvador/warts pathway. Mutations in a second class of genes, the neoplastic tumor-suppressor genes, disrupt proteins that function either as scaffolds at cell-cell junctions (scribble, discs large, lgl) or as components of the endocytic pathway (avalanche, rab5, ESCRT components). For the third group, the nonautonomous tumor-suppressor genes, mutant cells stimulate the proliferation of adjacent wild-type cells. Understanding the interactions between these three classes of genes will improve our understanding of how cell and tissue growth are coordinated during organismal development and perturbed in disease states such as cancer.
Mechanisms of Cyclic-di-GMP Signaling in Bacteria
Authors: Jenal Urs , Malone Jacob
Published: July 2006

Cyclic-di-GMP is a ubiquitous second messenger in bacteria. The recent discovery that c-di-GMP antagonistically controls motility and virulence of single, planktonic cells on one hand and cell adhesion and persistence of multicellular communities on the other has spurred interest in this regulatory compound. Cellular levels of c-di-GMP are controlled through the opposing activities of diguanylate cyclases and phosphodiesterases, which represent two large families of output domains found in bacterial one- and two-component systems. This review concentrates on structural and functional aspects of diguanylate cyclases and phosphodiesterases, and on their role in transmitting environmental stimuli into a range of different cellular functions. In addition, we examine several well-established model systems for c-di-GMP signaling, including Pseudomonas, Vibrio, Caulobacter, and Salmonella.
Cell Cycle Regulation in Plant Development
Authors: Inzé Dirk , De Veylder Lieven
Published: July 2006

Cell cycle regulation is of pivotal importance for plant growth and development. Although plant cell division shares basic mechanisms with all eukaryotes, plants have evolved novel molecules orchestrating the cell cycle. Some regulatory proteins, such as cyclins and inhibitors of cyclin-dependent kinases, are particularly numerous in plants, possibly reflecting the remarkable ability of plants to modulate their postembryonic development. Many plant cells also can continue DNA replication in the absence of mitosis, a process known as endoreduplication, causing polyploidy. Here, we review the molecular mechanisms that regulate cell division and endoreduplication and we discuss our understanding, albeit very limited, on how the cell cycle is integrated with plant development.
Bacterial Contingency Loci: The Role of Simple Sequence DNA Repeats in Bacterial Adaptation
Authors: Moxon Richard , Bayliss Chris , Hood Derek
Published: July 2006

Bacterial pathogens face stringent challenges to their survival because of the many unpredictable, often precipitate, and dynamic changes that occur in the host environment or in the process of transmission from one host to another. Bacterial adaptation to their hosts involves either a mechanism for sensing and responding to external changes or the selection of variants that arise through mutation. Here we review how bacterial pathogens exploit localized hypermutation, through polymerase slippage of simple sequence repeats (SSRs), to generate phenotypic variation and enhanced fitness. These SSRs are located within the reading frame or in the promoter of a subset of genes, often termed contingency loci, whose functions are usually involved in direct interactions with host structures.
The Law and Economics of Incomplete Contracts
Authors: Scott Robert E.
Published: July 2006

▪ Abstract  Individual actors want to make their promises enforceable in order to motivate mutually profitable investments. But parties cannot easily design contracts that maximize beneficial investments and also respond appropriately to changing conditions. Although economists have designed theoretical models that maximize joint welfare both ex ante and ex post, these mechanisms depend on a perfectly functioning and costless system of enforcement. In the real world, parties must expend substantial resources to enforce commitments legally, and, in many cases, courts lack information to assess the parties' actions. This review examines one of the main insights of the theory of incomplete contracts: that legal enforcement alone cannot ensure the full realization of jointly beneficial cooperative ventures. Legal enforcement, supported by the coercive power of the state, is only one mechanism for inducing cooperation, and in many relationships it typically has only a limited role to play. Complex contracts do lend themselves to effective formal enforcement. But parties often choose to write simple contracts that look to renegotiation once the future is known. Simple contracts require enforcement by informal mechanisms, such as reputation, repeated dealings, and norms of reciprocity in order to motivate both beneficial investment ex ante and adjustment ex post.
The Cosmic Microwave Background for Pedestrians: A Review for Particle and Nuclear Physicists
Authors: Samtleben Dorothea , Staggs Suzanne , Winstein Bruce
Published: July 2006

We intend to show how fundamental science is drawn from the patterns in the temperature and polarization fields of the cosmic microwave background (CMB) radiation, and thus to motivate the field of CMB research. We discuss the field's history, potential science and current status, contaminating foregrounds, detection and analysis techniques, and future prospects. Throughout the review we draw comparisons to particle physics, a field that has many of the same goals and that has gone through many of the same stages.
Results from the Relativistic Heavy Ion Collider
Authors: Müller Berndt , Nagle James L.
Published: July 2006

▪ Abstract  This review describes the current status of the heavy ion research program at the Relativistic Heavy Ion Collider (RHIC). The new suite of experiments and the collider energies have opened up new probes of the medium created in the collisions. Our review focuses on the experimental discoveries to date at RHIC and their interpretation in light of the field's present theoretical understanding of the dynamics of relativistic heavy ion collisions and of the structure of strongly interacting matter at high energy density.
High dexamethasone concentration prevents stimulatory effects of TNF-α and LPS on IL-6 secretion from the precursors of human muscle regeneration
Authors: Prelovsek Oja , Mars Tomaz , Jevsek Marko , Podbregar Matej , Grubic Zoran
Published: July 2006

A frequent finding in patients surviving critical illness myopathy is chronic muscle dysfunction. Its pathogenesis is mostly unknown; one explanation could be that muscle regeneration, which normally follows myopathy, is insufficient in these patients because of a high glucocorticoid level in their blood. Glucocorticoids can prevent stimulatory effects of proinflammatory factors on the interleukin (IL)-6 secretion, diminishing in this way the autocrine and paracrine IL-6 actions known to stimulate proliferation at the earliest, myoblast stage of muscle formation. To test this hypothesis, we compared the effects of major proinflammatory agents [tumor necrosis factor (TNF)-α and endotoxin lipopolysaccharide (LPS)] on the IL-6 secretion from the muscle precursors and then studied the influence of dexamethasone (Dex) on these effects. Mononuclear myoblasts, which still proliferate, were compared with myotubes in which this capacity is already lost. For correct interpretation of results, cultures were examined for putative apoptosis and necrosis. We found that constitutive secretion of IL-6 did not differ significantly between myoblasts and myotubes; however, the TNF-α- and LPS-stimulated IL-6 release was more pronounced ( P < 0.001) in myoblasts. Dex, applied at the 0.1–100 nM concentration range, prevented constitutive and TNF-α- and LPS-stimulated IL-6 release at both developmental stages but only at high concentration ( P < 0.01). Although there are still missing links to it, our results support the concept that high concentrations of glucocorticoids, met in critically ill patients, prevent TNF-α- and LPS-stimulated IL-6 secretion. This results in reduced IL-6-mediated myoblast proliferation, leading to the reduced final mass of the regenerated muscle.