bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrating indigenous ecological knowledge and customary sea tenure with marine and social science for conservation of bumphead parrotfish (Bolbometopon muricatum) in the Roviana Lagoon, Solomon Islands
Authors: ASWANI SHANKAR , HAMILTON RICHARD J.
Published: April 2004

Indigenous ecological knowledge and customary sea tenure may be integrated with marine and social science to conserve the bumphead parrotfish (Bolbometopon muricatum) in the Roviana Lagoon, Western Solomon Islands. Three aspects of indigenous ecological knowledge in Roviana were identified as most relevant for the management and conservation of bumphead parrotfish, and studied through a combination of marine science and anthropological methods. These were (1) local claims that fishing pressure has had a significant impact on bumphead parrotfish populations in the Roviana Lagoon; (2) the claim that only small bumphead parrotfish were ever seen or captured in the inner lagoon and that very small fish were restricted to specific shallow inner-lagoon nursery regions; and (3) assertions made by local divers that bumphead parrotfish predominantly aggregated at night around the new moon period and that catches were highest at that time. The research supported claims (1) and (2), but did not support proposition (3). Although the people of the Roviana Lagoon had similar conceptions about their entitlement rights to sea space, there were marked differences among regional villages in their opinions regarding governance and actual operational rules of management in the Lagoon. Contemporary differences in management strategies resulted from people's historical and spatial patterns of settlement across the landscape and adjoining seascapes, and the attendant impact of these patterns on property relations. This was crucial in distinguishing between those villages that held secure tenure over their contiguous sea estates from those that did not. Indigenous ecological knowledge served to (1) verify that the bumphead parrotfish was a species in urgent need of protection; (2) explain how different habitats structured the size distribution of bumphead parrotfish; (3) identify sensitive locations and habitats in need of protection; and (4) explain the effect of lunar periodicity on bumphead parrotfish behaviour and catch rates. Secure customary sea tenure identified locations best suited to bumphead parrotfish management programmes, with a greater likelihood for local participation and programme success. The information was used to establish two marine protected areas in the region for bumphead parrotfish conservation.
Changes in structure and cover of a common property pine forest in Guatemala, 1954–1996
Authors: HOLDER CURTIS D.
Published: April 2004

Concern about increasing rates of deforestation of tropical forests has resulted in investigations into the viability of local land-use practices and communal forms of governance. The majority of people in Guatemala live in regions where primary forests are absent. Several secondary forests in the highly populated highlands of Guatemala are communally managed forests, and people depend on forest products from these secondary forests for their livelihood. This study examines changes in forest structure and coverage of a native Pinus oocarpa Schiede communally managed forest in San Jose La Arada, Chiquimula in eastern Guatemala from 1954–1996. The pine forest is a municipal-communal property. The municipality has title to the land, however the forests are communal property. Neither forest committees in the villages nor municipal government regulations establish communal management of the pine forest; instead there are customary rules in the villages that guide forest extraction. People from the surrounding villages extract fuelwood, ocote (resin-rich wood harvested from the tree trunk and used for kindling) and timber from the pine forest. The P. oocarpa forest is situated in a seasonally dry region with nutrient-poor and highly eroded soils. Aerial photographs from 1954 and 1987 were compared to estimated changes in forest cover. Changes in forest structure are based on data collected from stand inventories conducted in 1987 and 1996. The pine forest was reduced in area by 14.4%, from 12.39 km2 in 1954 to 10.61 km2 in 1987. Additionally, stand density and basal area were reduced by 12% and 41%, respectively, from 1987–1996. Fuelwood and timber for domestic use were not extracted at a sustainable rate between 1954 and 1996 from the communally managed pine forest in this study. A sustainable-use management plan, in which all villages surrounding the forest participate, is recommended to provide future forest products for the villages.
Poverty and forest degradation: introduction to the special issue
Authors: SHIVELY GERALD E.
Published: April 2004

This special issue focuses on the poor and their role in forest degradation. The idea that the poor are both agents of forest degradation and victims of forest loss is not new. Neither is the observation that unsustainable rates of forest use by smallholder farmers arises as a result of a complex interplay of incentives, constraints, and institutional forces. For researchers and policy makers concerned with natural resource use in low-income settings, theory is often useful, but rarely adequate to explain behavioural patterns. Unambiguous theoretical findings tend to flow only from substantial sets of simplifying assumptions, and such assumptions, measured against the observed facts of smallholder agriculture, seem largely untenable. Unfortunately much empirical research on the topic suffers from an opposite problem. In settings where, at any point in time, everything matters and nothing is held constant, econometric findings are frequently weak. The combination of heterogeneity of circumstance, homogeneity of market signals, and limitations on smallholder response generally overwhelms the statistical power of small data sets, often collected with different purposes in mind.
Household welfare and forest dependence in Southern Malawi
Authors: FISHER MONICA
Published: April 2004

This paper examines the role forests play in alleviating poverty in rural Malawi. Data from three villages in southern Malawi indicate high levels of forest dependence. Gini decomposition shows that access to forest income reduced measured income inequality at the study sites. Tobit analysis of the determinants of reliance on low-return and high-return forest activities indicates that asset-poor households are more reliant on forest activities compared with the better off; reliance on high-return activities is conditioned also by availability of adult male labor and location. Taken together, the study's findings suggest that forests prevent poverty by supplementing income, and may also help to improve the living standards of households that are able to enter into high-return forest occupations. Policy implications are discussed.
Seeing the forest for the fuel
Authors: PATTANAYAK SUBHRENDU K. , SILLS ERIN O. , KRAMER RANDALL A.
Published: April 2004

We demonstrate a new approach to understanding the role of fuelwood in the rural household economy by applying insights from travel cost modeling to author-compiled household survey data and meso-scale environmental statistics from Ruteng Park in Flores, Indonesia. We characterize Manggarai farming households' fuelwood collection trips as inputs into household production of the utility yielding service of cooking and heating. The number of trips taken by households depends on the shadow price of fuelwood collection or the travel cost, which is endogenous. Econometric analyses using truncated negative binomial regression models and correcting for endogeneity show that the Manggarai are ‘economically rational’ about fuelwood collection and access to the forests for fuelwood makes substantial contributions to household welfare. Increasing cost of forest access, wealth, use of alternative fuels, ownership of kerosene stoves, trees on farm, park staff activity, primary schools and roads, and overall development could all reduce dependence on collecting fuelwood from forests.
Educating the MTV Generation: Legal Information Skills Online
Authors: Smith Nicki McLaurin , Presser Prue
Published: March 2004

This article is a summary of the paper presented at the 34th Annual Study Conference of BIALL held in Cardiff, June 2003 by Nicki McLaurin Smith and Prue Presser. The paper consisted of a demonstration of LIST (Legal Information Skills Tutorial), which has been developed at the University of Melbourne Law School for the purpose of teaching legal research skills. The paper covered background information, evaluation, successes and shortcomings as well as extending an invitation for involvement in future collaborative projects of this nature with the Legal Resource Centre.
Practical Legal Research Skills – The Law Firm Librarian's Viewpoint
Authors: Mosley Caroline
Published: March 2004

The effect of the Practical Legal Research (PLR) modules of the Legal Practice Course (LPC) course was the main focus of the discussions. The views within this article are general observations from the participants' experiences of working with trainee solicitors. The panel consisted of librarians from a range of different-sized law firms with representation from the academic sector. Comments were also received from our colleagues in barristers' chambers.
IT in the Law
Authors: Tomlinson Jo
Published: March 2004

Jo Tomlinson was responsible for this column, with support from Lindsey. Jo & Lindsey's contact details are given at the end and they will be very pleased to hear from any re-aders who have material to contribute to the column.
Current Awareness
Authors: Sands Gillian , Weston-Smith Sam
Published: March 2004

This Current Awareness column, and previous Current Awareness columns, are now fully searchable in the new caLIM database (Current Awareness for Legal Information Managers). The caLIM database is available on the Institute of Advanced Legal Studies website at: http://ials.sas.ac.uk/library/caware/caware.htm
THEORIZING AMERICA
Authors: RODGERS DANIEL T.
Published: April 2004

James E. Block, A Nation of Agents: The American Path to a Modern Self and Society (Cambridge, MA: Belknap Press of Harvard University Press, 2002)

Sheldon S. Wolin, Tocqueville Between Two Worlds: The Making of a Political and Theoretical Life (Princeton, NJ: Princeton University Press, 2001)
Solvent‐Free Enzymatic Synthesis of 1,3‐Diconjugated Linoleoyl Glycerol Optimized by Response Surface Methodology
Authors: Guo Zheng , Sun Yan
Published: April 2004

An operation mode with N2 bubbling under vacuum was employed for the solvent‐free synthesis of 1,3‐diconjugated linoleoyl glycerol (1,3‐dCLG) from conjugated linoleic acid (CLA) catalyzed by Novozym 435. The response surface methodology (RSM) was adopted for the optimization of the reaction conditions with five major factors (incubation time, temperature, enzyme load, substrate mole ratio, and system vacuum) and three responses (CLA conversion, 1,3‐dCLG yield, and acyl migration). Two sets of optimal conditions were recommended. Validation of the RSM model was verified by the good agreement between the experimental and the predicted values of 1,3‐dCLG yield. Under the optimal conditions, the yield of 1,3‐dCLG up to 93% was obtained. The reaction was scaled up to a production level of 100 g of 1,3‐dCLG at a yield of 90.7%, indicating a promising feature of the technology in industrial applications.
Effect of Streptavidin RGD Mutant on the Adhesion of Endothelial Cells
Authors: Chan Bernard P. , Reichert William M. , Truskey George A.
Published: April 2004

Adhesion of endothelial cells (EC) to surfaces can be enhanced by supplementing the integrin‐mediated adhesion with high‐affinity streptavidin (SA) that links a biotinylated EC to a biotinylated surface. Biotin pullout from the EC membrane limits the effectiveness of this treatment, leading to a predominance of EC detachment by cohesive failure. In this study we investigated whether a RGD‐SA mutant that links SA to EC integrin receptors, and eliminates EC biotinylation, improves EC adhesion. Suspended EC were incubated with the RGD‐SA mutant prior to cell seeding, primarily via attachment to the RGD binding site on αvβ3 integrin. RGD‐SA‐incubated EC were subsequently seeded onto a surface preadsorbed with a mixture of fibronectin (Fn) and biotinylated bovine serum albumin (b‐BSA). Results showed EC adhesion supplemented with the RGD‐SA‐biotin system significantly increased cell retention under flow, critical shear stresses for detachment, focal contact area, and force per bond relative to SA used with biotinylated EC. These increases were accompanied by significant reductions in membrane fragments left behind following EC detachment, which suggested cohesive failure via cell membrane rupture was significantly reduced, and enhanced phosphorylation of focal adhesion kinase, which suggested activation and clustering of integrin receptors. Together, these results show that the integrin‐independent augmentation of EC adhesion using SA‐biotin can be further improved through use of an RGD‐SA mutant.
Enzyme Encapsulation in Permeabilized Saccharomyces cerevisiae Cells
Authors: Chow Chi‐Kin , Palecek Sean P.
Published: April 2004

The Saccharomyces cerevisiae cell wall provides a semipermeable barrier that can retain intracellular proteins but still permits small molecules to pass through. When S. cerevisiae cells expressing E. coli lacZ are treated with detergent to extract the cell membrane, β‐galactosidase activity in the permeabilized cells is approximately 40% of the activity of the protein in cell extract. However, the permeabilized cells can easily be collected and reused over 15 times without appreciable loss in activity. Cell wall composition and thickness can be modified using different cell strains for enzyme expression or by mutating genes involved in cell wall biosynthesis or degradation. The Σ1278b strain cell wall is less permeable than the walls of BY4742 and W303 cells, and deleting EXG1, which encodes a 1,3‐β‐glucanase, can further reduce permeability. A short Zymolyase treatment can increase cell wall permeability without rupturing the cells. Encapsulating multiple enzymes in permeabilized cells can offer kinetic advantages over the same enzymes in solution. Regeneration of ATP from AMP by adenylate kinase and pyruvate kinase encapsulated in the same cell proceeded more rapidly than regeneration using a cell extract. Combining permeabilized cells containing adenylate kinase with permeabilized cells containing pyruvate kinase can also regenerate ATP from AMP, but the kinetics of this reaction are slower than regeneration using cell extract or permeabilized cells expressing both enzymes.
Reversible Immobilization of Glutaryl Acylase on Sepabeads Coated with Polyethyleneimine
Authors: Alonso‐Morales Noelia , López‐Gallego Fernando , Betancor Lorena , Hidalgo Aurelio , Mateo Cesar , Fernández‐Lafuente Roberto , Guisán Jose M.
Published: April 2004

The immobilizaton of the enzyme glutaryl‐7‐aminocephalosporanic acid acylase (GA) was performed via ionic adsorption onto several supports: a new anionic exchange resin, based on the coating of Sepabeads internal surfaces with polyethyleneimine (PEI) of different molecular weights, and conventional EC‐Q1A‐Sepabeads and DEAE‐agarose. Immobilization occurred very rapidly in all cases, but the adsorption strength was much higher in the case of PEI‐Sepabeads than in the other supports at pH 7 (e.g., at 150 mM NaCl, 90% of the enzyme was eluted from the DEAE agarose and 15% was eluted from the EC‐Q1A‐Sepabeads, whereas no desorption was detected with the best PEI‐Sepabeads). Interestingly, the adsorption strength of the GA was increased when it was immobilized on PEI‐Sepabeads with higher molecular weights. For instance, enzyme desorption was detected from 75 mM NaCl for the derivative prepared onto Sepabeads coated with PEI 700 Da, whereas in the derivative prepared with the highest molecular weight PEI (600 000 Da) no enzyme desorption was detected below 150 mM NaCl. Optimal PEI‐Sepabeads (prepared with PEI of 600 000 Da) was even much more thermostable than the covalent derivative prepared onto cyanogen bromide agarose. Moreover, this derivative presented a half‐life 26‐fold higher than that of the soluble enzyme at 45 °C, and the support could be reused 10 times after the full desorption of the enzyme without decreasing loading capacity.
A Dynamic Mathematical Model To Clarify Signaling Circuitry Underlying Programmed Cell Death Control in Arabidopsis Disease Resistance
Authors: Agrawal Vikas , Zhang Chu , Shapiro Allan D. , Dhurjati Prasad S.
Published: April 2004

Plant cells undergo programmed cell death in response to invading pathogens. This cell death limits the spread of the infection and triggers whole plant antimicrobial and immune responses. The signaling network connecting molecular recognition of pathogens to these responses is a prime target for manipulation in genetic engineering strategies designed to improve crop plant disease resistance. Moreover, as alterations to metabolism can be misinterpreted as pathogen infection, successful plant metabolic engineering will ultimately depend on controlling these signaling pathways to avoid inadvertent activation of cell death. Programmed cell death resulting from infection of Arabidopsis thaliana with Pseudomonas syringae bacterial pathogens was chosen as a model system. Signaling circuitry hypotheses in this model system were tested by construction of a differential‐equations‐based mathematical model. Model‐based simulations of time evolution of signaling components matched experimental measurements of programmed cell death and associated signaling components obtained in a companion study. Simulation of systems‐level consequences of mutations used in laboratory studies led to two major improvements in understanding of signaling circuitry: (1) Simulations supported experimental evidence that a negative feedback loop in salicylic acid biosynthesis postulated by others does not exist. (2) Simulations showed that a second negative regulatory circuit for which there was strong experimental support did not affect one of two pathways leading to programmed cell death. Simulations also generated testable predictions to guide future experiments. Additional testable hypotheses were generated by results of individually varying each model parameter over 2 orders of magnitude that predicted biologically important changes to system dynamics. These predictions will be tested in future laboratory studies designed to further elucidate the signaling network control structure.
Bioprocess Parameters and Oxygen Transfer Characteristics in β‐Lactamase Production by Bacillus Species
Authors: Çelik Eda , Çalık Pınar
Published: April 2004

After screening potential β‐lactamase producers in a medium containing penicillin G, an inducible ( Bacillus subtilis NRS 1125) and a constitutive ( Bacillus licheniformis 749/C ATCC 25972) β‐lactamase producer were selected. As the highest enzyme activity was obtained with B. licheniformis 749/C, the effects of the concentration of carbon sources, i.e., glucose, fructose, sucrose, citric acid, and glycerol, and nitrogen sources, i.e., (NH4)2HPO4, NH4Cl, yeast extract, casamino acids and peptone, pH, and temperature on β‐lactamase production were investigated with B. licheniformis 749/C in laboratory scale bioreactors. Among the investigated media, the highest volumetric activity was obtained as 270 U cm−3 in the medium containing 10.0 kg m−3 glucose, 1.18 kg m−3 (NH4)2HPO4, 8.0 kg m−3 yeast extract, and the salt solution at 32 °C and pH0 = 6.0. By using the designed medium, fermentation and oxygen transfer characteristics of the bioprocess were investigated at V = 3.0 dm3 bioreactor systems with a VR = 1.65 dm3 working volume at QO/ VR = 0.5 vvm and N = 500 min‐1. At the beginning of the process the Damköhler number was <1, indicating that the process was at biochemical reaction limited condition; at t = 2–5 h both mass‐transfer and biochemical reaction resistances were effective; and at t = 6–10 h ( Da ≫1) the bioprocess was at mass transfer limited condition. Overall oxygen transfer coefficients ( KLa) varied between 0.01 and 0.03 s−1, enhancement factor ( KLa/ KLaO) varied between 1.2 and 2.3, and volumetric oxygen uptake rate varied between 0.001 and 0.003 mol m−3 s−1 throughout the bioprocess. The specific oxygen uptake and the specific substrate consumption rates were the highest at t = 2 h and then decreased with the cultivation. The maximum yield of cells on substrate and the maximum yield of cells on oxygen values were obtained, respectively, as YX/S = 0.34 and YX/O = 1.40, at t = 5 h, whereas the highest yield of substrate on oxygen was obtained as YS/O = 6.94 at t = 3.5 h. The rate of oxygen consumption for maintenance and the rate of substrate consumption for maintenance values were found, respectively, as mO = 0.13 kg kg−1 h−1 and mS = 3.02 kg kg−1 h−1.
Oxidative Burst in Suspension Culture of Taxus cuspidataInduced by a Laminar Shear Stress in Short‐Term
Authors: Han Rong‐Bin , Yuan Ying‐Jin
Published: April 2004

Generation of active oxidative species induced by shear stress in suspension cultures of Taxus cuspidata was investigated in a Couette‐type shear reactor. It was found that T. cuspidata cells respond to a shear rate of 95 s−1 with oxidative bursts. Their triphasic characteristics in 6 h were similar in both intracellular H2O2 production and extracellular O2−• production. Additionally, inhibition studies with diphenylene iodonium and azide suggested that the key enzyme responsible for oxidative bursts under the shear rate of 95 s−1 is primarily NADPH oxidase and the contribution of peroxidase for oxidative bursts was less. Investigation of the relationship between active oxidative species and defense responses induced by the shear stress indicated that the O2−• burst may account for the change of membrane permeability, and the H2O2 burst plays an important role in inducing secondary metabolites such as the activation of phenylalanine ammonia lyase enzyme and phenolic accumulation. Furthermore, oxidative bursts elicited by the shear rate of 95 s−1 were suppressed by treatment with suramin, nifedipine, and neomycin prior to the shear stress treatment, suggesting that G‐protein, Ca2+ channel, and phospholipase C are involved in the signal pathway for oxidative bursts induced by the shear stress. A model is proposed to explain the oxidative burst in cultured T. cuspidata cells challenged with the shear stress.
Genetically Engineered Fluorescent Cell Marker for Labeling CD34+ Hematopoietic Stem Cells
Authors: Ye Kaiming , Jin Sha , Schultz Jerome S.
Published: April 2004

To address the challenge of labeling and tracking stem cells in vivo, we have engineered a fluorescent cell marker CD34EGFP by utilizing the mechanism of the cell‐specific activity of CD34 promoter in CD34+ stem cells. A retroviral vector derived from a murine stem cell virus was constructed to integrate the CD34EGFP gene into the genome of the cells for labeling. Our experiment demonstrates that the 454 bp segment upstream of the murine CD34 cDNA sequence has full function of promoter activity and can serve as a cell‐specific promoter for driving the expression of EGFP in CD34+ hematopoietic stem cells (HSC), providing a living color for labeling stem cells. The CD34EGFP marker was tested in various types of cells, including terminally differentiated cells, CD34+ mouse myeloid leukemia progenitor cells, CD34− hematopoietic cells, and CD34+ HSCs. We show that the engineered CD34EGFP cell marker is expressed in the CD34+ stem or progenitor cells but not in CD34− or terminally differentiated cells. RT‐PCR assay indicates that the transcription level of the CD34EGFP gene from CD34 promoter is almost the same as that from CMV promoter in CD34+ progenitor cells. The approach we present here offers a framework for genetic engineering of fluorescent cell markers for labeling and tracking stem cells in vivo. We anticipate that a variety of cell markers could be generated by coupling variants of fluorescent proteins with various cell‐specific promoters.
Combining Synthetic and Analytical Strategies for Preparative HPLC Enantioseparation of Monastrol Racemic Mixture
Authors: Cavazzini Alberto , Massi Alessandro , Bergamaschi Giovanni , Braga Stefano , Dondi Francesco , Dondoni Alessandro
Published: April 2004

Large‐scale resolution of racemic monastrol has been carried out by normal‐phase mode HPLC on an amylose‐based chiral stationary phase. Because monastrol solubility, in media of proper compositions for normal‐mode HPLC separations (in terms of retention factors and selectivity), was significantly low and impractical for preparative scopes, racemic monastrol was transformed into the corresponding O‐ tert‐butyldimethylsilyl derivative. The tert‐butyldimethylsilyl group was chosen as a suitable derivatizing agent because it induced approximatively a six‐times higher solubility and allowed for an almost quantitative recovery of pure monastrol from the derivatization‐deprotection sequence. The competitive isotherms of the O‐tert‐butyldimethylsilyl compounds, measured through frontal analysis, were fitted to competitive Langmuir and four‐parameter bi‐Langmuir models. The equilibrium dispersive model of chromatography was used for modeling the nonlinear separation of the racemate and to optimize the experimental conditions for collection of highly concentrated fractions of pure (R,S)‐O‐tert‐butyldimethylsilyl compounds, from which significant amounts of the corresponding enantiomers of monastrol (about 100 mg of each enantiomer with 30 runs on an analytical‐scale column) were obtained by quantitative back‐derivatization.
Modeling and Biokinetics in Anaerobic Acidogenesis of Starch‐Processing Wastewater to Acetic Acid
Authors: Ahn Johng‐Hwa , Lee Sangyoung , Hwang Seokhwan
Published: April 2004

Starch‐processing wastewater was anaerobically treated to produce acetic acid in laboratory‐scale, continuously stirred tank reactors. The optimal conditions, in which the maximum acetic acid production occurred, were 0.56 d hydraulic retention time, pH 5.9, and 36.1 °C. Acetic acid production at the optimum conditions was 672 ± 20 mg total organic carbonequivalent L−1, which indicated a 75% conversion efficiency of influent total organic carbon into acetic acid. A fourth order Runge‐Kutta approximation was used to determine the Monod kinetics of the acidogens by using unsteady‐state data from continuous unsteady‐state experiments at the optimum conditions. The model outputs and experimental data fit together satisfactorily, suggesting that the unsteady‐state approach was appropriate for the evaluation of acidogenic biokinetics. These included μm, Ks, Y, and kd, which were evaluated as being 0.13 h−1, 25 mg total carbohydrate (TC) L−1, 0.38 mg volatile suspended solid mg−1 TC, and 0.002 h−1, respectively.
Sensitivity of static stress calculations to the earthquake slip distribution
Authors: Steacy Sandy , Marsan David , Nalbant Suleyman S. , McCloskey John
Published: April 2004

The apparent strong correlation between Coulomb stress changes and the spatial distribution of aftershocks suggests the possibility of making near‐real‐time estimations of areas at risk of experiencing off‐fault aftershocks. In order to do this in practice a number of issues must first be addressed, including the extent to which the main shock slip must be known in detail before a meaningful stress map can be constructed. Here we investigate this issue by constructing a time‐ordered sequence of slip solutions for the Landers earthquake, computing Coulomb stress changes for each solution, and quantitatively comparing the stress field with the observed aftershocks by (1) resolving the Coulomb stress change onto the aftershock nodal planes and calculating the percentage of events consistent with triggering and (2) constructing a two‐dimensional map of Coulomb stress and computing the correlation coefficient between the positive and negative areas and the locations of the aftershocks. We find that slip solutions based on empirical relations and either focal mechanism or moment tensor data produce stress fields inconsistent with the observed spatial distribution of aftershocks, whereas slip solutions incorporating the correct rupture geometry but greatly simplified slip produce stress fields consistent with the aftershock distribution when very near‐fault events are excluded. We further find that resolving stress perturbations onto earthquake nodal planes and computing the percentage of events experiencing positive Coulomb stress provides a poor measure of success because of the limited range of structures on which events occur and the compatibility of the main shock stress field with these structures. Our results support the hypothesis that Coulomb stress changes affect the spatial distribution of aftershocks and suggest that meaningful calculations of Coulomb stress can be made as soon as an earthquake's rupture geometry is well constrained.
Transient simulations of Holocene atmospheric carbon dioxide and terrestrial carbon since the Last Glacial Maximum
Authors: Joos Fortunat , Gerber Stefan , Prentice I. C. , Otto‐Bliesner Bette L. , Valdes Paul J.
Published: April 2004

Conflicting hypotheses are investigated for the observed atmospheric CO2 increase of 20 ppm between 8 ka BP and pre‐industrial time. The carbon component of the Bern Carbon Cycle Climate (Bern CC) model, which couples the Lund‐Potsdam‐Jena Dynamic Global Vegetation Model to an atmosphere‐ocean‐sediment component, is driven by climate fields from time‐slice simulations of the past 21 ka with the Hadley Centre Unified Model or the NCAR Climate System Model. The entire Holocene ice core record of CO2 is matched within a few ppm for the standard model setup, and results are broadly consistent with proxy data of atmospheric 13CO2, mean ocean δ13C, and pollen data, within their uncertainties. Our analysis suggests that a range of mechanisms, including calcite compensation in response to earlier terrestrial uptake, terrestrial carbon uptake and release, SST changes, and coral reef buildup, contributed to the 20 ppm rise. The deep sea δ13C record constrains the contribution of the calcite compensation mechanism to 4–10 ppm. Terrestrial carbon inventory changes related to climate and CO2 forcing, the greening of the Sahara, peat buildup, and land use have probably influenced atmospheric CO2 by a few ppm only. The early Holocene CO2 decrease is quantitatively explained by terrestrial uptake and calcite compensation in response to terrestrial uptake during the glacial‐interglacial transition. The recent hypothesis by Ruddiman [2003] that anthropogenic land use caused a 40 ppm CO2 anomaly over the past 8 ka, preventing the climate system from entering a new glacial, would imply an anthropogenic emission of 700 GtC and a decrease in atmospheric δ13C of 0.6 permil. This is not compatible with the ice core δ13C record and would require an upward revision of land use emission estimates by a factor of 3 to 4.
Transition from rifted continental to oceanic crust at the southeastern Korean margin in the East Sea (Japan Sea)
Authors: Cho Hyun‐Moo , Kim Han‐Joon , Jou Hyeong‐Tae , Hong Jong‐Kuk , Baag Chang‐Eob
Published: April 2004

The southeastern Korean margin documents the processes of continental rifting and seafloor spreading that eventually led to the opening of the southern part of the East Sea (Japan Sea). Two‐dimensional crustal structure of the southeastern Korean margin was computed from ocean bottom seismometer data by tomographic inversion and iterative forward modeling. The crustal structure shows the emplacement of high‐velocity (>7 km/s) lower crust under the continental shelf and slope area associated with a rapid transition from rifted continental to oceanic crust. The high‐velocity lower crust is interpreted as magmatic underplating formed by voluminous igneous activity during rifting. Magnetic modeling confirms its primary correlation with a prominent magnetic anomaly along the edge of the Korean Peninsula. We suggest that the rifting and subsequent seafloor spreading at the Korean margin was significantly controlled by the supply of magma in a region of hotter than normal mantle temperature.
Time resolved study of simulated volcanic lightning by laser induced plasma in a plume of ablated basalt
Authors: Sobral Hugo , Sanginés de Castro Roberto , Villagrán‐Muniz Mayo , Navarro‐González Rafael
Published: March 2004

Lightning activity is typically generated by explosive volcanic activity. In this work we report an experimental simulation of a volcanic lightning by focusing into a basaltic rock the emission of a pulsed Nd: YAG laser in air at atmospheric pressure (laser ablation). The temporal evolution of air breakdown in an ash plume was studied by emission spectroscopy and shadowgraphy. The electron temperature exceeds 18 × 103 K and the electron density reaches about 1018 cm−3. The production yield of nitric oxide by simulated volcanic lightning was determined by gas chromatography coupled to a mass spectrometer and no substantial difference was found with that of simulated thunderstorm lightning by laser induced plasma.
Crustal thickness beneath the Andes and Sierras Pampeanas at 30°S inferred from Pn apparent phase velocities
Authors: Fromm R. , Zandt G. , Beck S. L.
Published: March 2004

We obtained a 2D crustal model beneath central Chile and western Argentina using apparent Pn phase velocities recorded along an EW trending transect at 30°S. This model is characterized by a thick (65 km) crustal root beneath the High Cordillera, a 60 km thick crust beneath the Precordillera, and a gradual shallowing of Moho depths beneath the Sierras Pampeanas from 55 km in the west to 40 km in the east. Beneath the Sierras Pampeanas, where very little crustal shortening is observed, the thick crust must be explained by means other than simple tectonic shortening. Isostatically balanced crustal thickness is consistently shallower than our model shows, suggesting the existence of dynamic forces possibly linked to the flat slab.
Coordinated optical and EISCAT observations of black aurora
Authors: Blixt E. M. , Kosch M. J.
Published: March 2004

An image intensified video camera was used in conjunction with the EISCAT radar in Tromsø, Norway, for detailed studies of non‐sheared black aurora on March 5, 2002. While it is known that a downward field‐aligned current will decrease the ionospheric plasma density, any measurable effect will depend on the noise‐level in the density measurements and the background density. The results show that the plasma density is not reduced in the regions of black aurora, which shows that if a downward current existed within the black aurora, it must be less than ∼0.6 μA/m2. Combining this result with recent findings that small scale currents are generally strong, that the downward currents are associated with intense diverging electric fields, and that the observed black arcs show no signs of shear motion, it is concluded that the non‐sheared black aurora is not associated with any significant downward field‐aligned current.
Geomagnetic and atmospheric effects upon the cosmogenic 10Be observed in polar ice
Authors: McCracken K. G.
Published: April 2004

Analytical tools are developed that allow the 10Be measured in ice cores to be inverted to yield quantitative information about the long term time dependence of the cosmic ray flux outside the Earth's magnetic field. It is concluded that the historic changes in both the magnitude, and direction of the geomagnetic dipole, and the inter‐ latitudinal mixing in the atmosphere, produce effects that can be large compared to the standard deviation of 22 year average 10Be data, and appropriate procedures are developed to compensate for them. The 10Be response function is shown to have peaked near 1.8 GeV/nucleon since 1950, while during the Maunder minimum it approximated 0.8 GeV/nucleon. This shows that the 10Be data are approximately a factor of two more sensitive to cosmic ray modulation than are high latitude sea level neutron monitors. The Z ≥ 2 cosmic radiation contributes 30% to 49% of the observed 10Be, introducing a substantial rigidity dependence into the temporal variations. A mathematical model is developed that computes the 10Be flux arriving at points in the polar cap, taking into account “polar wander”, changes in the geomagnetic moment, and various degrees of atmospheric mixing. It is shown that polar wander introduces variations into the observed flux that may be approximately three times the standard deviation of 22 year average 10Be data, and that there may be significant differences between the northern and southern hemispheres. The mathematical model, together with the temporal changes in the nitrate concentration observed in ice cores, indicate that the secular changes in 10Be due to climate driven changes in atmospheric circulation were <4% during the “little ice ages”. Two methods are outlined that allow independent determinations of the characteristics of the region of the atmosphere that contributes to the 10Be observed in the polar caps. For the Antarctic, this has approximated the region south of 40°S for the past millennium. Frequently, 10Be measurements are made using 4–8 year ice samples, and it is shown that the unresolved 11 year variations of the cosmic radiation are the dominant source of statistical variation in these data, and a procedure developed to largely eliminate them. Failure to eliminate these unresolved 11 year variation greatly diminishes the value of the 10Be data in the study of the long term changes in the galactic cosmic radiation.
Effects of photoionization on propagation and branching of positive and negative streamers in sprites
Authors: Liu Ningyu , Pasko Victor P.
Published: April 2004

Modeling studies indicate that double‐headed streamers originating from single electron avalanches in lightning‐driven quasi‐static electric fields at mesospheric altitudes accelerate and expand, reaching transverse scales from tens to a few hundreds of meters and propagation speeds up to one tenth of the speed of light, in good agreement with recent telescopic, high‐speed video and multichannel photometric observations of sprites. The preionization of the medium ahead of a streamer by the ionizing UV photons originating from a region of high electric field in the streamer head (i.e., photoionization) significantly modifies the streamer scaling properties as a function of air pressure in comparison with those predicted by similarity laws. The photoionization leads to lower peak electric fields in the streamer head, lower streamer electron densities, wider initial streamer structures, and lower acceleration and expansion rates of streamers at sprite altitudes 40–90 km, when compared to the ground level. The primary reason for the observed differences is that the effective quenching altitude of the excited states of the molecular nitrogen b1Πu, b′1, and c′41 that give photoionizing radiation is about 24 km. The quenching of these states is therefore negligible at sprite altitudes, leading to a substantial enhancement of the electron‐ion pair production ahead of the streamer tip because of the photoionization, when compared to the ground level. The maximum radius of the expanding streamers is predominantly controlled by the combination of the absorption cross section χmin = 3.5 × 10−2 cm−1 Torr−1 of the molecular oxygen (O2) at 1025 Å and the partial pressure of O2 in air, Streamers exhibit branching when their radius becomes greater than Model results indicate a lower branching threshold radius for positive streamers in comparison with negative streamers, under otherwise identical ambient conditions. These results are in good agreement with recent results of high‐speed photography of laboratory streamers in near‐atmospheric pressure N2/O2 mixtures and similar morphology documented during recent telescopic and high‐speed video observations of sprites.
On the temperature anisotropy of the core part of the proton velocity distribution function in the solar wind
Authors: Marsch E. , Ao X.‐Z. , Tu C.‐Y.
Published: April 2004

In this paper we analyze the temperature anisotropy of velocity distribution functions (VDFs) of protons measured by the Helios spacecraft in fast solar wind. We concentrate on data obtained during the primary mission, including the first perihelion passage, of Helios 2 in a distance range between 0.98 and 0.29 AU for the days 23 through 114 of the year 1976. The main goal is to provide solid statistical evidence on the relation between the anisotropy and the proton plasma beta, parameters that play a key role in the regulation of the shape of the core. It is believed to be formed by resonant interactions between ion cyclotron waves and protons, as described by the quasi‐linear theory of pitch angle diffusion. In the analysis of the VDF, particular attention is paid to the symmetry axis, which can be determined by the directions of either the magnetic field, the proton heat flux, or the alpha‐proton relative drift. We analyze in detail the core part of the proton VDF, carefully avoiding a possible influence of the proton beam component.
Effect of directivity on estimates of radiated seismic energy
Authors: Venkataraman Anupama , Kanamori Hiroo
Published: March 2004

To accurately estimate the seismic energy radiated in an earthquake, it is important to use appropriate corrections for path and source effects. Using slip models obtained by inversion of seismic data, we examine the effect of directivity on estimates of radiated energy and develop a method to correct for this source effect. From our calculations we suggest that the directivity correction for the earthquakes we studied is less than a factor of three; we also conclude that the directivity correction for dip‐slip earthquakes with rupture propagating along strike is less than a factor of two at teleseismic distances. Thus teleseismic energy estimates of large subduction zone earthquakes will not be significantly affected by directivity.
Contrasts in seismic wave speeds and density across the 660‐km discontinuity beneath the Philippine and the Japan Seas
Authors: Tseng Tai‐Lin , Chen Wang‐Ping
Published: March 2004

Using triplicate waveforms, we construct 34 seismic profiles east of Taiwan to investigate lateral variations of P and S wave speeds (VP and VS) near the mantle transition zone. Data from broadband and densely spaced, short‐period arrays are combined to achieve high resolution. We find correspondingly high VS in the back arc of Izu‐Bonin where the Northern Philippine Sea Anomaly (NPSA) was previously delineated in the lower portion of the transition zone by an average VP that is 1.5 ± 0.5% higher than the surrounding regions. High VS of the NPSA reduces the contrast in VS across the 660‐km discontinuity (ΔVS) to about 3.9%, consistent with the notion that NPSA reflects a subhorizontal remnant of cold Pacific slab, resting immediately above the lower mantle. The aseismic NPSA contrasts the Fiji‐Tonga region where many outboard earthquakes, low VP and VS and seismic anisotropy mark a large‐scale, petrologic anomaly. The contrasting pattern implies that the NPSA is no longer cold enough to preserve materials such as metastable olivine or volatiles that can trigger earthquakes, reduce VP and VS, and cause anisotropy. In regions surrounding the NPSA, ΔVS is well constrained to be 5.9 ± 0.5%. This precise result and known impedance contrast (∼7%) under the Japan Sea lead to a density contrast (Δρ) of about 8%, circumventing the trade‐off between Δρ and ΔVS. The magnitude of Δρ is higher than recent estimates (∼5%) without independent control on ΔVS, but close to longstanding global models, implying considerable resistance to slab penetration into the lower mantle north of the NPSA.
Mapping of tide and tidal flow fields along a tidal channel with vessel‐based observations
Authors: Li Chunyan , Blanton Jack , Chen Changsheng
Published: March 2004

We present the results of a study focused on the tidal regime of a shallow channel with a large intertidal area. Data from a vessel‐towed acoustic Doppler current profiler (ADCP) were used to infer tidal constituents for both tidal elevation and tidal current along an upstream portion of the Okatee River, South Carolina. The tidal elevation is estimated from the depth recorded by the moving ADCP. This tidal elevation is then used to correct the vertical coordinates of each depth bin below the ADCP for the velocity profiles. The ability to resolve both tidal elevation and velocity allows us to determine that the tide is a standing wave. A statistical analysis demonstrates that the along‐channel velocity has a stronger tidal signal (larger R2 values) than the across‐channel velocity. When only the M2 and mean components are included in the harmonic analysis, about 75% of the covered area along the ship track has a “good fit,” where at least 70% of the variability can be explained by the tidal and mean components. By adding the M4 component to the harmonic analysis, an additional 2% of the covered area has “good fit” for the elevation, depth‐averaged velocity, and mid‐depth velocity, but 12% for the near‐surface velocity. The observed spatial distribution of the residual flow is in reasonable agreement with that predicted by an unstructured grid, finite‐volume coastal ocean model (FVCOM).
Water masses and circulation pathways through the Iceland Basin during Vivaldi 1996
Authors: Pollard R. T. , Read J. F. , Holliday N. P. , Leach H.
Published: March 2004

Quasi‐synoptic data from late 1996 spanning the subpolar North Atlantic have been used to determine the major pathways of the North Atlantic Current (NAC) at that time. High spatial resolution allows fronts to be accurately positioned on each SeaSoar section. A clearly defined front of the NAC (the Southern Branch) turns north at around 25°W and continues through the middle of the Iceland Basin as far as 60°N, 20°W. A second branch (the Northern Branch or SubArctic Front) turns north around 30°W and retroflects westward north of 54°N to re‐enter the Irminger Basin and become part of the Irminger Current up the western side of the Reykjanes Ridge. A third, eastward branch turns sharply northwest at the mouth of the Rockall Trough to skirt the southwestern margin of Hatton Bank. This branch carries a tongue of saline eastern North Atlantic water (ENAW) over Hatton Bank and in consequence ENAW covers the whole of the Hatton and Rockall Banks as well as the Rockall Trough, bounded in the west by the Southern Branch. The most saline water, found in Rockall Trough, spills out into the northern Iceland Basin between Rockall and Lousy Banks. This saline, weakly stratified tongue can be traced westward to the south of Iceland continuing southwestward along the eastern flank of the Reykjanes Ridge. Subarctic Intermediate Water is carried into the Iceland Basin, creating a fresh tongue bounded east and west by the more saline ENAW over Hatton Bank and the eastern flank of the Reykjanes Ridge respectively.