bluuebunny/crossref_metadata_2025 huggingface dataset:
Centrifugal partition chromatography: A survey of its history, and our recent advances in the field
Authors: Marchal Luc , Legrand Jack , Foucault Alain
Published: July 2003

Centrifugal partition chromatography (CPC) was introduced in 1982 by Sanki Eng. And for almost 20 years this company remained the only one manufacturing such an apparatus. A CPC instrument or a CPC column is a series of channels linked in cascade by ducts and aligned in cartridges or disks in a circle around a rotor; setting the rotor in motion submits this assembly to a constant centrifugal field. The originality of CPC is that it uses any biphasic liquid‐liquid system as mobile and stationary phases. The United States branch of Sanki contributed greatly to the worldwide acceptance of the technique. Recent works performed in the Netherlands and in France have, by means of visualization of flow‐patterns in CPC channels, contributed to a better knowledge of hydrodynamics and mass transfer phenomena. Nowadays research in our laboratory focuses on speediness and scale‐up of the technique. © 2003 The Japan Chemical Journal Forum and Wiley Periodicals, Inc., Chem Rec 3: 133–143; 2003: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10057
Microbial genes and enzymes in the degradation of chlorinated compounds
Authors: Ogawa Naoto , Miyashita Kiyotaka , Chakrabarty A. M.
Published: July 2003

Microorganisms are well known for degrading numerous natural compounds. The synthesis of a multitude of chlorinated compounds by the chemical industry and their release into the natural environment have created major pollution problems. Part of the cause of such pollution is the inability of natural microorganisms to efficiently degrade synthetic chlorinated compounds. Microorganisms are, however, highly adaptable to changes in the environment and have consequently evolved the genes that specify the degradation of chlorinated compounds to varying degrees. Highly selective laboratory techniques have also enabled the isolation of microbial strains capable of utilizing normally recalcitrant highly chlorinated compounds as their sole source of carbon and energy. The evolution and role of microbial genes and enzymes, as well as their mode of regulation and genetic interrelationships, have therefore been the subjects of intense study. This review emphasizes the genetic organization and the regulation of gene expression, as well as evolutionary considerations, regarding the microbial degradation of chlorobenzoates, chlorocatechols, and chlorophenoxyacetic acids. © 2003 The Japan Chemical Journal Forum and Wiley Periodicals, Inc., Chem Rec 3: 158–171; 2003: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10059
Cluster, facets, and edges: Site‐dependent selective chemistry on model catalysts
Authors: Freund H.‐J. , Libuda J. , Bäumer M. , Risse T. , Carlsson A.
Published: July 2003

More than activity, selectivity of catalytic reactions is the focus of research in the 21st century. We review studies on model systems that address the issue of directing a catalytic reaction on disperse metal catalysts by controlling the specific surface site. Three examples are explored: methanol dehydrogenation over Pd/alumina, NO dissociation on Pd/alumina, and reaction studies for molecules relevant in a Fischer‐Tropsch scenario on a bimetallic Pd/Co/alumina model catalyst. We show how surface science can be used by combining a variety of experimental techniques to study the chemistry of model catalysts at the atomic level. © 2003 The Japan Chemical Journal Forum and Wiley Periodicals, Inc., Chem Rec 3: 181–200; 2003: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10060
New reactions of 1‐alkynes catalyzed by transition metal complexes
Authors: Wakatsuki Yasuo , Hou Zhaomin , Tokunaga Makoto
Published: July 2003

Recently discovered catalytic reactions with ruthenium and lanthanide metal complexes have extended the scope of 1‐alkynes as useful reagents. The specific formation of aryl‐substituted (Z)‐1,3‐enynes via the dimerization of HCCR1 (R1 = aryl) has been attained using dimeric lanthanide complexes, the catalytic activity of which appears to be unaffected by time. The dimerization of HCCR2 (R2 = t‐Bu, SiMe3) catalyzed by Ru(cod)(cot)/PR3 or RuH2(PPh3)3 produces a good yield of butatrienes (Z)‐R2CHCCCHR2 with a high degree of selectivity. Under certain conditions, HCCSiMe3 dimerizes to yield exclusively (Z)‐M3SiCCCHCHSiMe3. The hydration of HCCR3 (R3 = alkyl, aryl) catalyzed by RuCl2/PR′3 or CpRuCl(PR″3)2 has realized the first example of anti‐Markovnikov regioselectivity in an addition reaction of water that produces aldehydes R3CH2CHO. The application of this reaction to propargylic alcohols has lead to their formal isomerization to α,β‐unsaturated aldehydes. In contrast, the addition of amines R4NH2 (R4 = aryl) to HCCR5 (R5 = alkyl, aryl) conforms to Markovnikov's rule to produce ketimines R5(CNR4)CH3 when catalyzed by a Ru3(CO)12/additive. Since the reaction can be performed in air without the need for any solvents, it enables the practical synthesis of aromatic ketimines, which are difficult to prepare by conventional methods. The synthesis of indoles using deactivated anilines is one practical application of this reaction. The mechanisms of some of these reactions have been analyzed in detail with the aid of theoretical calculations. © 2003 The Japan Chemical Journal Forum and Wiley Periodicals, Inc., Chem Rec 3: 144–157; 2003: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10061
Pulmonary responses of acute exposure to ultrafine iron particles in healthy adult rats
Authors: Zhou Ya‐Mei , Zhong Cai‐Yun , Kennedy Ian M. , Pinkerton Kent E.
Published: July 2003

As critical constituents of ambient particulate matter, transition metals such as iron may play an important role in health outcomes associated with air pollution. The purpose of this study was to determine the respiratory effects of inhaled ultrafine iron particles in rats. Sprague Dawley rats 10–12 weeks of age were exposed by inhalation to iron particles (57 and 90 μg/m3, respectively) or filtered air (FA) for 6 h/day for 3 days. The median diameter of particles generated was 72 nm. Exposure to iron particles at a concentration of 90 μg/m3 resulted in a significant decrease in total antioxidant power along with a significant induction in ferritin expression, GST activity, and IL‐1β levels in lungs compared with lungs of the FA control or of animals exposed to iron particles at 57 μg/m3. NFκB–DNA binding activity was elevated 1.3‐fold compared with that of control animals following exposure to 90 μg/m3 of iron, but this change was not statistically significant. We concluded that inhalation of iron particles leads to oxidative stress associated with a proinflammatory response in a dose‐dependent manner. The activation of NFκB may be involved in iron‐induced respiratory responses, but further studies are merited. © 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 227–235, 2003.
Effect of Microcystis aeruginosa and Nodularia spumigena on survival of Eurytemora affinis and the embryonic and larval development of the Baltic herring Clupea harengus membras
Authors: Ojaveer Evald , Simm Mart , Balode Maija , Purina Ingrida , Suursaar Ülo
Published: July 2003

Laboratory experiments were carried out to investigate the effect of two strains of Microcystis aeruginosa and a strain of Nodularia spumigena on the survival of Eurytemora affinis (Copepoda) and on the embryonic and larval development of the Baltic spring‐spawning herring Clupea harengus membras. The trials were made in water taken from Pärnu Bay, at a salinity of 3.7–5.1 psu, a constant temperature (15°C ± 1°C in trials with Eurytemora and herring embryos; 18°C ± 2°C with herring larvae), and an oxygen concentration of 8.8–10.4 ppm. The strains tested had a negative impact on the survival of Eurytemora, as well as on the embryonic development and hatching regime of the Baltic herring. In Eurytemora the response depended on the sex of the animals: the survival was clearly higher in females. In the embryonic stages of herring, the influence resulted in an increase in deviations from the normal pattern of development and a higher mortality. The impact of the strains on the larval development of herring was rather moderate. © 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 236–242, 2003.
Domain architecture of the polyglutamine protein ataxin‐3: a globular domain followed by a flexible tail
Authors: Masino Laura , Musi Valeria , Menon Rajesh P. , Fusi Paola , Kelly Geoff , Frenkiel Thomas A. , Trottier Yvon , Pastore Annalisa
Published: July 2003

Anomalous expansion of a polyglutamine (polyQ) tract in the protein ataxin‐3 causes spinocerebellar ataxia type 3, an autosomal dominant neurodegenerative disease. Very little is known about the structure and the function of ataxin‐3, although this information would undoubtedly help to understand why the expanded protein forms insoluble nuclear aggregates and causes neuronal cell death. With the aim of establishing the domain architecture of ataxin‐3 and the role of the polyQ tract within the protein context, we have studied the human and murine orthologues using a combination of techniques, which range from limited proteolysis to circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopies. The two protein sequences share a highly conserved N‐terminus and differ only in the length of the glutamine repeats and in the C‐terminus. Our data conclusively indicate that ataxin‐3 is composed by a structured N‐terminal domain, followed by a flexible tail. Moreover, [15N]glutamine selectively labelled samples allowed us to have a direct insight by NMR into the structure of the polyQ region.
Macropexophagy in Hansenula polymorpha: facts and views
Authors: Kiel Jan A.K.W , Komduur Janet A , van der Klei Ida J , Veenhuis Marten
Published: July 2003

The hallmark of eukaryotic cells is compartmentalization of distinct cellular functions into specific organelles. This necessitates the cells to run energetically costly mechanisms to precisely control maintenance and function of these compartments. One of these continuously controls organelle activity and abundance, a process termed homeostasis. Yeast peroxisomes are favorable model systems for studies of organelle homeostasis because both the proliferation and degradation of these organelles can be readily manipulated. Here, we highlight recent achievements in regulation of peroxisome turnover in yeast, in particular Hansenula polymorpha, with a focus on directions of future research.
Influence of neopterin on the generation of reactive oxygen species in human neutrophils
Authors: Razumovitch Julia A , Semenkova Galina N , Fuchs Dietmar , Cherenkevich Sergey N
Published: July 2003

Neopterin is synthesized by human monocyte‐derived macrophages primarily upon stimulation with the cytokine interferon‐γ. We studied the influence of neopterin on the generation of reactive oxygen species (ROS) in human peripheral blood neutrophils. Radical formation was measured using a biochemiluminometer. Neutrophils were isolated from peripheral blood of healthy donors. The generation of ROS by neutrophils suspended in Earl's solution (pH=7.4) at 37°C was investigated by monitoring of chemiluminescence using luminol and lucigenin as light emitters. Neopterin induced chemiluminescence in suspensions of neutrophils in the presence of luminol, but not of lucigenin. Neopterin affected only adhesive cells. Addition of neopterin into the suspension of the cells involving D‐mannitol, L‐histidine and diazabicyclo[2.2.2]octane (DABCO) decreased luminol‐dependent chemiluminescence (LDCL) of the neutrophils. The action of superoxide dismutase (SOD) and 2‐phenyl‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide (PTIO) reduced neopterin‐induced LDCL of neutrophils. Data suggest that neutrophils respond on exposure to neopterin with additional generation of singlet oxygen, hydroxyl radical and nitric oxide by nicotinamide adenine dinucleotide phosphate (NADPH)‐independent pathways.
Regulation of hypoxia inducible factor‐1 by nitric oxide in contrast to hypoxia in microvascular endothelium
Authors: Natarajan Ramesh , Fisher Bernard J , Fowler Alpha A
Published: July 2003

Hypoxia activates the transcription factor, hypoxia inducible factor‐1 (HIF‐1). Besides hypoxia, HIF‐1 can be activated under normoxic conditions by nitric oxide. The signal transduction pathways involved in HIF‐1α stabilization, HIF‐1 DNA binding and transactivation by NO and hypoxia in microvascular endothelium remains unknown. We report that protein phosphorylation is involved in HIF‐1 activation during hypoxia and NO. The phosphatidylinositol 3‐kinase (PI‐3K)/Akt pathway has differential effects on HIF‐1 activation by hypoxia and NO. Our data indicate that the PI‐3K/Akt pathway is insufficient for HIF‐1α induction by hypoxia. The lipid and protein phosphatase activities of PTEN also appear to be involved in regulation of HIF‐1α by NO.
Fusion of family 2b carbohydrate‐binding module increases the catalytic activity of a xylanase from Thermotoga maritima to soluble xylan
Authors: Kittur Farooqahmed S. , Mangala Selanere L. , Rus’d Ahmed Abu , Kitaoka Motomitsu , Tsujibo Hiroshi , Hayashi Kiyoshi
Published: July 2003

A family 2b carbohydrate‐binding module from Streptomyces thermoviolaceus STX‐II was fused at the carboxyl‐terminus of XynB, a thermostable and single domain family 10 xylanase from Thermotoga maritima, to create a chimeric xylanase. The chimeric enzyme (XynB‐CBM2b) was purified and characterized. It displayed a pH–activity profile similar to that of XynB and was stable up to 90°C. XynB‐CBM2b bound to insoluble birchwood and oatspelt xylan. Whereas its hydrolytic activities toward insoluble xylan and p‐nitrophenyl‐β‐xylopyranoside were similar to those of XynB, its activity toward soluble xylan was moderately higher than that of XynB.
Structural studies on a twin‐arginine signal sequence
Authors: Kipping Marc , Lilie Hauke , Lindenstrauß Ute , Andreesen Jan R , Griesinger Christian , Carlomagno Teresa , Brüser Thomas
Published: July 2003

Translocation of folded proteins across biological membranes can be mediated by the so‐called ‘twin‐arginine translocation’ (Tat) system. To be translocated, Tat substrates require N‐terminal signal sequences which usually contain the eponymous twin‐arginine motif. Here we report the first structural analysis of a twin‐arginine signal sequence, the signal sequence of the high potential iron‐sulfur protein from Allochromatium vinosum. Nuclear magnetic resonance (NMR) analyses of amide proton resonances did not indicate a signal sequence structure. Accordingly, data from H/D exchange matrix‐assisted laser desorption/ionization‐time of flight (MALDI‐TOF) mass spectrometry showed that the amide protons of the signal sequence exchange rapidly, indicating the absence of secondary structure in the signal sequence up to L29. We conclude that the conserved twin‐arginine motif does not form a structure by itself or as a result of intramolecular interactions.
Mosaic particles formed by wild‐type hepatitis B virus core protein and its deletion variants consist of both homo‐ and heterodimers
Authors: Kazaks Andris , Dishlers Andris , Pumpens Paul , Ulrich Rainer , Krüger Detlev H. , Meisel Helga
Published: July 2003

Co‐expression in Escherichia coli of wild‐type (wt) hepatitis B virus core protein (HBc) and its naturally occurring variants with deletions at amino acid positions 77–93 or 86–93 leads to formation of mosaic particles, which consist of three dimer subunit compositions. These compositions are wt/variant HBc heterodimers and two types of homodimers, formed by wt HBc or the variant HBc themselves. Mosaic particles were found also when both HBc deletion variants 77–93 and 86–93 were co‐expressed in E. coli. These findings are discussed in terms of their significance for hepatitis B virus pathogenesis and prospective use of mosaic particles in vaccine development.
Neurotransmitter release: the dark side of the vacuolar‐H+ATPase
Authors: Morel N.
Published: July 2003

Vacuolar‐H+ATPase (V‐ATPase) is a complex enzyme with numerous subunits organized in two domains. The membrane domain V0 contains a proteolipid hexameric ring that translocates protons when ATP is hydrolysed by the catalytic cytoplasmic sector (V1). In nerve terminals, V‐ATPase generates an electrochemical proton gradient that is acid and positive inside synaptic vesicles. It is used by specific neurotransmitter‐proton antiporters to accumulate neurotransmitters inside their storage organelles. During synaptic activity, neurotransmitters are released from synaptic vesicles docked at specialized portions of the presynaptic plasma membrane, the active zones. A fusion pore opens that allows the neurotransmitter to be released from the synaptic vesicle lumen into the synaptic cleft. We briefly review experimental data suggesting that the membrane domain of V‐ATPase could be such a fusion pore. We also discuss the functional implications for quantal neurotransmitter release of the sequential use of the same V‐ATPase membrane domain in two different events, neurotransmitter accumulation in synaptic vesicles first, and then release from these organelles during synaptic activity.
Calmodulin‐dependent regulation of a lipid binding domain in the v‐SNARE synaptobrevin and its role in vesicular fusion
Authors: De Haro Luc , Quetglas Stéphanie , Iborra Cécile , Lévêque Christian , Seagar Michael
Published: July 2003

Trans SNARE complex assembly is an essential step in Ca2+‐dependant membrane fusion, although the SNARE proteins do not bind Ca2+ ions. Studies to evaluate how the Ca2+sensor protein calmodulin might regulate this process led to the identification of a consensus calmodulin binding motif in the v‐SNARE VAMP2. This sequence (residues 77–90) is situated precisely C‐terminal to the tetanus toxin (TeNT) and botulinum B toxin cleavage site (76Q‐F77) close to the transmembrane anchor. The same domain also binds acidic phospholipids and Ca2+/calmodulin or lipid binding are mutually exclusive. Directed mutagenesis of basic or hydrophobic residues within this motif reduced interactions with both Ca2+/calmodulin and phospholipids to a similar extent. The effects of these mutations on Ca2+‐dependent exocytosis was explored using an hGH release assay in permeabilized pheochromocytoma PC12 cells. Treatment of cells with tetanus toxin (TeNT), which cleaves endogenous VAMP, abolished secretion. Secretion could be re‐established by transfecting TeNT‐resistant VAMP with mutations (Q76V, F77W) in the cleavage site. However rescue of exocytosis was abolished when additional mutations (K83A, K87V or W89A, W90A) were introduced that inhibited calmodulin and phospholipid binding to VAMP. Thus calmodulin and/or phospholipid binding to the membrane proximal region of VAMP is required for Ca2+‐dependent exocytosis. We speculate that interactions between cis phospholipids at the vesicle surface and the membrane proximal region of VAMP inhibits SNARE complex assembly. Displacement of these interactions by Ca2+/calmodulin may promote SNARE complex assembly and lead to trans interactions between the membrane proximal region of VAMP and phospholipids in the plasma membrane.
The nature of anterior knee pain following injection of hypertonic saline into the infrapatellar fat pad
Authors: Bennell Kim , Hodges Paul , Mellor Rebecca , Bexander Catharina , Souvlis Tina
Published: July 2003

The infrapatellar fat pad has been implicated as a possible source of anterior knee pain. This study examined the nature, distribution and time‐course of experimentally induced pain in the infrapatellar fat pad. Hypertonic saline (5%) was injected into the medial fat pad of 11 healthy individuals with no history of knee pain. Severity of pain was assessed at rest and during activity using an 11 point numerical rating scale (NRS) at regular intervals over 15–30 min following injection. Participants described the size of the pain region from a series of different sized circles while the area and type of pain was established from a body chart and the McGill pain questionnaire. The effect of pain on temperature‐pain threshold and sensory thresholds of the anterior knee was assessed. Participants generally reported a deep aching pain that peaked in severity around 3 min and gradually declined over 15 min. Pain levels were not altered by clinical manoeuvres designed to impinge the fat pad. The size of the pain region was related to pain intensity. Pain was most commonly felt in the region of the fat pad medial to the patella, although some individuals reported proximal referred pain as far as the groin region. Thermal and sensory thresholds were not altered at a region close to the injection site during the experimental pain. These results suggest that nociceptive stimulation of the infrapatellar fat pad may cause anterior knee pain that is not necessarily confined locally particularly if pain is severe. This has implications for the investigation of pathological structures in patients presenting clinically with anterior knee pain and provides an experimental model of anterior knee pain. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Lead induced effects on acetylcholinesterase activity in cerebellum and hippocampus of developing rat
Authors: Reddy Gottipuolu R. , Basha Md.Riyaz , Devi C.Bhuvaneswari , Suresh Ambati , Baker John L. , Shafeek Abdul , Heinz Josephine , Chetty Chellu S.
Published: July 2003

Exposure to low‐levels of lead (Pb) during early development has been implicated in behavioral abnormalities and cognitive deficits in children. The present study is focused on developmental changes in hippocampus and cerebellum of rats following perinatal exposure to Pb. Pregnant rats were exposed to 0.2% Pb‐acetate from gestation day 6 (GD 6) through postnatal day (PND) 21 and the activity levels of acetylcholinesterase (AChE) were estimated in cerebellum and hippocampus of pups at specific time points for 5 weeks. In both the brain regions, Pb‐exposure decreased AChE activity with an increase in age. Histochemical observations conducted in 35 days old rat brain showed decreased AChE activity conspicuously in stratum oriens and dentate gyrus of hippocampus, and molecular and granule cell layers of cerebellum. In vitro studies conducted in 35 days old rat brain showed a considerable decrease in the specific activity of AChE at high concentrations (50–100 μM) of Pb in a concentration‐dependent manner. However, at low concentrations (5–20 μM), Pb failed to produce such changes. In the presence of eserine (physostigmine), the specific inhibitor of AChE, the inhibitory effect of Pb was potentiated and this was more pronounced at low‐concentrations of Pb. The behavioral responses in open‐field also showed a significant decrease in both Pb exposed as well as eserine administered rats. These data suggest that low‐level perinatal Pb‐exposure induces alterations in cholinergic system in the cerebellum and hippocampus of developing brain even after the withdrawal of Pb‐exposure, that may contribute to behavioral and learning deficits.
Evidence that oxidative stress is involved in the inhibitory effect of proline on Na+,K+‐ATPase activity in synaptic plasma membrane of rat hippocampus
Authors: Franzon Renata , Lamers Marcelo L. , Stefanello Francieli M. , Wannmacher Clóvis M.D. , Wajner Moacir , Wyse Angela T.S.
Published: July 2003

In the present study, we investigated the effect of Vitamins E and C on the inhibition of Na+,K+‐ATPase activity provoked by proline (Pro) administration in rat hippocampus. Five‐day‐old rats were pretreated for 1 week with daily i.p. administration of saline (control) or Vitamin E (40 mg/kg) and Vitamin C (100 mg/kg). Twelve hours after the last injection, animals received one single injection of Pro (12.8 μmol/g of body weight) or saline and were killed 1 h later. Results showed that Na+,K+‐ATPase activity was decreased in the Pro‐treated rats and that the pretreatment with Vitamins E and C prevented this effect. In another set of experiments, we investigated the in vitro effect of 1.0 mM Pro on Na+,K+‐ATPase activity from synaptic membranes of hippocampus of rats. Pro significantly inhibited (30%) Na+,K+‐ATPase activity. We also evaluated the effect of preincubating glutathione, trolox and Nϖ‐nitro‐l‐arginine methyl ester (l‐NAME) alone or combined with Pro on Na+,K+‐ATPase activity. Tested drugs did not alter Na+,K+‐ATPase activity, but glutathione prevented the inhibitory effect of Pro on this enzyme activity. These results suggest that the in vivo and in vitro inhibitory effect of Pro on Na+,K+‐ATPase activity is probably mediated by free radicals that may be involved in the neurological dysfunction found in hyperprolinemic patients.
Increment at molt for the Norway lobster (Nephrops norvegicus) from the south coast of Portugal
Authors: Castro M , Encarnação P , Henriques P
Published: July 2003

The increment at molt for Nephrops norvegicus was studied with the objective of obtaining a model for prediction of post-molt size based on pre-molt size for the population from the south coast of Portugal. Wild animals were maintained in a specially prepared laboratory facility until they molted. Individual values of increment at molt were obtained and used to evaluate alternative models and estimate their parameters. Six alternative models, used previously by several authors to relate pre- and post-molt size, were modified so that increment at molt was the dependent variable and pre-molt size the independent variable. These included the linear relationship of the growth factor (GF) on pre-molt size, the Hiatt equation, post-molt size a power function of pre-molt size, the hyperbolic function, GF exponential function of pre-molt size and the Misra equation.

The analysis of the data showed that none of the models could be used to predict increment at molt for either sex. The distribution of the increment at molt was a random normal variable, with mean values not significantly different between sexes, 2.78 mm for males and 2.26 mm for females, variances 0.47 and 0.59, respectively.

An analysis of the models suggests that using post-molt size or the GF as dependent variables may lead to a misinterpretation of the dependency of these variables on pre-molt size. It is suggested that the increment at molt should be the variable of interest for predicting post-molt size. The choice of a mathematical formulation should, besides having biological meaning, have the capacity of expressing a true relationship between increment at molt and pre-molt carapace length, namely, be able to model several options for the increment at molt after maturity, including a steady increase of the increment through life, the stabilization of the increment after maturity or the decrease of the increment for larger sizes.
Accounting for length- and depth-dependent diel variation in catchability of fish and invertebrates in an annual bottom-trawl survey
Authors: Benoít Hugues P , Swain Douglas P
Published: July 2003

Diel variation in the catchability of 51 species of fish and 13 invertebrate taxa from an annual bottom-trawl survey of the southern Gulf of St. Lawrence was examined using generalized linear (Poisson) models. Two approaches were used: comparative fishing based on spatially paired day and night tows, and statistical control of spatio-temporal effects in regular survey data. The two approaches provided remarkably similar results. Furthermore, species-specific results were consistent between survey time periods where different vessels were used, and were quite comparable to results from other studies conducted in separate geographic areas. Where sufficient data existed, we considered both length and depth dependencies in diel variation in catchability. We commonly found significant length dependency for groundfish species and the pervasive pattern was for higher nighttime catches of small fish, the magnitude of the effect generally decreasing with increasing length. In contrast, water depth had a much less important impact, except for a few species. When considered jointly, however, patterns in length/depth dependency were not always clear. Given length-dependent geographic and bathymetric patterns in species distribution, the potential for confounding length and depth dependencies exists and correction factors for diel variation in catchability need to be applied cautiously.
Age determination, validation and growth of Grand Bank yellowtail flounder (Limanda ferruginea)
Authors: Dwyer Karen S , Walsh Stephen J , Campana Steven E
Published: July 2003

Yellowtail flounder (Limanda ferruginea) (Storer, 1839) on the Grand Bank off Newfoundland were traditionally aged using surface-read whole otoliths. Age determination of otoliths from recaptures of fish tagged in the early 1990s indicated that the traditional ageing technique was underestimating the ages of yellowtail flounder when compared with the time at liberty. Age comparisons between whole and thin-sectioned otoliths showed agreement in age readings up to 7 years; thereafter whole otoliths tended to give much lower ages than those estimated by thin sections. Length–frequency analysis of pelagic and demersal juveniles, captive rearing of juveniles and marginal increment analysis all corroborated age determination based on thin sections. Tag-recaptures and bomb radiocarbon assays validated age interpretations based on thin sections in young and old yellowtail flounder, respectively. Ages were validated up to 25 years for females and 21 years for males. However, because of increased narrowing of annuli in thin-sectioned otoliths from old fish, even thin sections may underestimate the true age of the fish. von Bertalanffy growth curve parameters (combined sexes) were L∞ = 55.6 cm total length, K=0.16 and t0=−0.003. These results challenge the conventional view that yellowtail flounder on the Grand Banks are a relatively fast growing, short-lived species.
Extraterrestrial solar spectrum 360–1050 nm from Rotating Shadowband Spectroradiometer measurements at the Southern Great Plains (ARM) site
Authors: Harrison Lee , Kiedron Peter , Berndt Jerry , Schlemmer James
Published: July 2003

Two years of Langley extrapolations made from the Southern Great Plains (SGP) site of the Atmospheric Radiation Measurement (ARM) Program using two very different RSS instruments and a NIST‐derived irradiance scale show larger extraterrestrial solar irradiances in the 400 to 600 nm domain by as much as 4.5% compared to the Neckel and Labs [1984] data. Our results are more congruent with that of Thuillier et al. [1998a, 1998b] in this domain but do not show larger irradiances than the Neckel and Labs data at wavelengths less than 400 nm. In addition to the question of the true extraterrestrial solar spectrum, the data we present here are directly useful for the interpretation of spectral measurements calibrated with current National Institute of Standards and Technology (NIST) irradiance standards, for which we believe this represents the most extensive determination of the solar irradiance.
Density as a controlling factor for seasonal and altitudinal variations of the auroral particle acceleration region
Authors: Morooka M. , Mukai T.
Published: July 2003

This paper reports on the statistical properties of the field‐aligned particle acceleration region at high latitudes above the auroral region observed by the Akebono (EXOS‐D) satellite. Akebono often observes downward accelerated electrons and upward accelerated ions at the same time, indicating that the satellite is inside the parallel acceleration region. We found three major regions of particle acceleration, two located in the dayside in the prenoon and postnoon sectors and one in the premidnight sector. In the dayside regions the average total field‐aligned potential difference is about 600 V (800 V in the summer postnoon region), and the occurrence frequency of the particle acceleration events is larger in the summer. In the premidnight region the average total field aligned potential difference is about 4 kV, and the occurrence frequency of the particle acceleration events is two times larger in the winter. An important result in this study is showing the altitude profile of the parallel acceleration region. In the dayside regions, more than 80% of the ion acceleration is observed above 6000 km in the summer, and more than 70% of the electron acceleration is observed below 8000 km in the winter. In the premidnight region, 90% of the ion acceleration is above 6000 km and more than 90% of electron acceleration is below 6000 km in summer and winter, respectively. We discuss these seasonal changes of the acceleration altitude in terms of seasonal variations of the ambient plasma density at altitude of the acceleration region, with a lower density during the winter, causing acceleration at lower altitude. The importance of the density at the altitude of acceleration is supported by the fact that Akebono does not observe any change of the relationship between the density at the bottom of the potential drop and the potential difference with changing season and altitude. Also the occurrence frequency of auroral electron acceleration is likely to be controlled by the seasonal changes of the ambient plasma density on auroral field lines.
Evidence for deep melting of hydrous metasomatized mantle: Pliocene high‐potassium magmas from the Sierra Nevadas
Authors: Elkins‐Tanton Linda T. , Grove Timothy L.
Published: July 2003

Phase equilibrium experiments have been conducted on a primitive Pliocene olivine leucitite (WC‐1) from the central Sierra Nevada, California. The near‐liquidus phase relations were determined from 1.2 to 3.4 GPa and at temperatures from 1350° to 1460°C in a piston‐cylinder apparatus. The composition with ∼2% H2O is multiply saturated with olivine and clinopyroxene at approximately 3.1 GPa and 1460°C and with 6% water in the coexisting melt phlogopite is stable. These results indicate that the magma was derived from a hydrous source at greater than 100 km depth. Xenoliths carried by other young Pliocene lavas in the vicinity of WC‐1 have yielded temperatures of equilibrium from 700° to 900°C, with one outlier at 1060°C. These xenoliths are consistent with the hypothesis that the lower lithosphere under the Sierra Nevada delaminated just prior to the Pliocene, and fluid‐metasomatized mantle melted to produce the high‐potassium Pliocene lavas. We suggest that subduction‐derived fluids drive a reaction that consumes garnet + orthopyroxene to create clinopyroxene + phlogopite, and that the high‐potassium Sierran magmas are created by melting phlogopite‐clinopyroxene metasomatized peridotite.
Mixed layer heat balance in the western North Pacific
Authors: Qu Tangdong
Published: July 2003

The mixed layer heat balance in the western North Pacific is examined using historical temperature data and U.S. National Centers for Environmental Prediction reanalysis surface wind and heat flux. Although the data come from different sources, the mixed layer heat budget is balanced reasonably well in the region studied. For the annual average, the surface thermal forcing is significant mainly in three regions. One is in the Mindanao Dome, where the incoming surface heat flux is balanced in a large part by the vertical entrainment induced by Ekman pumping. The second occurs in the Kuroshio region, where much of the heat advected by the Kuroshio is released to the atmosphere. The third is located in the central subtropical gyre where the annually integrated surface thermal forcing is balanced primarily by vertical entrainment associated with the deepening of the mixed layer. Although seasonal variation in sea surface temperature (SST) is mainly due to surface thermal forcing, ocean dynamics also has an effect, particularly, during the developing stage of the summer monsoon. From late May to early July, there is a northeastward increase in SST (>29°C) in the region 120°–160°E, 10°–20°N, which coincides with the northeastward onset of the summer monsoon. As the summer monsoon develops, vertical entrainment becomes effective at cooling, leading to a decrease in SST against the incoming surface heat flux over a large part of the western North Pacific.
Observation of current variations off the New Guinea coast including the 1997–1998 El Niño period and their relationship with Sverdrup transport
Authors: Ueki Iwao , Kashino Yuji , Kuroda Yoshifumi
Published: July 2003

Seasonal and interannual variations of the New Guinea Coastal Current (NGCC) and New Guinea Coastal Undercurrent (NGCUC) were investigated by examining the 5 years' data from acoustic Doppler current profiler moorings at two sites (2°S 142°E, 2.5°S 142°E) off the New Guinea coast. The NGCC flowed northwestward as is usual and intensified during the boreal summer, then weakened or even reversed direction to southeastward during the boreal winter. This seasonal change correlated to the monsoonal wind variation. However, during the 1997–1998 El Niño, the southeastward NGCC during the boreal winter was not observed, and northwestward flow was dominant throughout the year. On the other hand, the NGCUC flowed steadily northwestward all year‐round and intensified during the boreal summer. During the growing phase of the El Niño, the NGCUC intensified, and its northwestward flow reached from the surface to a depth of 250 m. Comparison between the volume transport of these currents and the Sverdrup transport along 2°S in the ocean interior indicated a mean difference of 13 × 106 m3 s−1 northward. The relationship between variations of these two transports showed a negative correlation on seasonal timescales except during the El Niño. During the mature phase of the El Niño, northward Sverdrup transport was enhanced significantly, furthermore the transport of these currents was also northward. The result demonstrates a process by which anomalous water volumes can flow into the equatorial region due to an imbalance between the volume transport in the ocean interior and the western boundary.
Cloud impacts on UV spectral actinic flux observed during the International Photolysis Frequency Measurement and Model Intercomparison (IPMMI)
Authors: Crawford J. , Shetter R. E. , Lefer B. , Cantrell C. , Junkermann W. , Madronich S. , Calvert J.
Published: July 2003

Observations collected during the International Photolysis Frequency Measurement and Model Intercomparison (IPMMI) have enabled a semiquantitative assessment of cloud impacts on UV spectral actinic flux. Critical to this analysis is the availability of spectroradiometer data accompanied by sky camera images. Data reveal several interesting aspects of cloud influences. Enhancements in UV actinic flux of up to 40% over clear‐sky values are observed for cloudy conditions when the solar disk is unoccluded. When the solar disk is occluded, reductions in actinic flux appear to vary inversely with cloud fraction in some instances. A wavelength dependence is also observed with shorter wavelengths generally exhibiting lower variability for both enhancements and reductions (e.g., 20–30% less variability at 320 versus 420 nm). Enhancements in actinic flux show a stronger wavelength dependence with increasing cloud fraction. By contrast, wavelength dependence appears to weaken with increasing cloud fraction for actinic flux reduction. At low Sun, however, a wavelength dependence appears to occur even for overcast conditions. Despite these differences, integration over longer periods shows cloud impacts on actinic flux to be similar for all UV wavelengths, suggesting that differences in wavelength response are localized phenomena with impacts that are minimized when integrated over the surrounding area. Further studies at other latitudes and in other seasons are needed to verify this behavior.
Northern Hemisphere circumpolar vortex trends and climate change implications
Authors: Frauenfeld Oliver W. , Davis Robert E.
Published: July 2003

Trends in the Northern Hemisphere circumpolar vortex at 700, 500, and 300 hPa are examined to assess the relationship between circulation variability and air temperature. A vortex climatology is developed for the period 1949–2000. At each pressure level, three geopotential height contours are used to quantify the size and position of the vortex at 5° longitude resolution within and both north and south of the primary hemispheric baroclinic zone. This combination of spatial specificity and the long temporal record makes this the most comprehensive vortex climatology to date. The overall and seasonal vortex time series for the Northern Hemisphere are created for northern, middle, and southern contours at each of the three levels in the atmosphere. From the beginning of the record until 1970, the vortex exhibits a statistically significant expansion, but the vortex has been contracting significantly since then at all levels. The pre‐1970 expansion and subsequent contraction is strongest in the lower latitudes and weakest in the higher latitudes. The trends are also stronger in the upper troposphere than in the lower troposphere. Spatial examination of the vortex indicates that the pre‐1970 expansion and post‐1970 contraction were driven primarily by expansion/contraction over Asia, Europe, and North America with little change over the Northern Hemisphere oceans. Although significant climate change debate focuses on the discrepancy between positive trends in surface air temperature and little or no trends in Microwave Sounding Unit (MSU) satellite temperatures, contraction of the circumpolar vortex at every level of the atmosphere implies that the atmosphere is warming at depth since 1970. Comparisons with the MSU temperature history indicate that the Northern Hemisphere circulation as a whole, as represented by the circumpolar vortex, accounts for almost two thirds of the interannual variability in midlatitude MSU temperature, indicating that vortex size and position are coupled strongly to atmospheric temperature and could be a good indicator of climate change. On a latitude‐by‐latitude and level‐by‐level basis, the lower latitudes are associated most strongly with MSU temperature in the midtroposphere while the middle and higher latitudes are more closely associated with MSU temperature in the upper troposphere. The vortex trends are also similar to observed surface warming trends.
Multifractal anisotropic scaling of the hydraulic conductivity
Authors: Tennekoon Lilantha , Boufadel Michel C. , Lavallee Daniel , Weaver James
Published: July 2003

We analyzed the scaling properties of the hydraulic conductivity K at three sites in Northern America: MADE, Borden, and Cape Cod. We found that K at all sites exhibits multifractality (fractal and multiscaling) in both the vertical and horizontal directions, though the multiscaling was within a range smaller than that of the maximum distance between measurements. In the vertical direction, the K data for MADE, Borden, and Cape Cod were multiscaling from 0.15 to 1.35 m, 0.05 to 0.5 m, and 0.15 to 0.9 m, respectively. They were multiscaling in the horizontal direction from 9 to 45 m, 1 to 10 m, and 1 to 17 m, respectively. The multiscaling was also anisotropic. Evidence of scaling was poorest for the horizontal direction of the MADE site, and it spanned half an order of magnitude. Such results compel one to treat multifractality in the horizontal direction of MADE as supported by heuristic arguments, rather than by pure statistical evaluation. We fitted a multifractal model to the data and estimated its parameters. We found the underlying statistics of all data to be non‐Gaussian, and the model capable of reproducing the probability distribution of K data, especially the negative skewness of log K. We also generated two‐dimensional isotropic multifractal fields illustrating the role of the parameters of the selected multifractal model.
Runoff production in blanket peat covered catchments
Authors: Holden Joseph , Burt Tim P.
Published: July 2003

Blanket peat catchments exhibit flashy regimes, but little is known about the exact nature of runoff production processes within these catchments. Catchment, hillslope, and plot‐scale monitoring results are presented from the blanket peats of the northern Pennines, United Kingdom. Catchment efficiency for three study catchments with areas of 11.4 km2, 0.83 km2, and 0.44 km2 were 72%, 77%, and 82%, respectively. Mean rainfall peak to discharge peak lag times were 2.7 hours, 2.1 hours, and 3.2 hours, respectively. Runoff from hillslopes in the catchments was gauged using runoff troughs. Mean hillslope lag times ranged from 0.6 to 2.2 hours, and despite large differences in the scale of study, there was little difference in response time. This indicates that slopes and channels are strongly hydrologically coupled in these peat systems. Saturation excess overland flow dominates hillslope runoff, particularly on more gentle slopes, and on footslopes where overland flow occurs most frequently. Overall, 81.5% of the total overland flow and matrix through flow collected by runoff troughs occurred at the peat surface, with 17.7% between the surface and 5 cm depth, 0.7% between 5 and 10 cm depth, and less than 0.1% from below 10 cm depth, despite the thickness of the peat deposit. Most storm flow is produced as saturation excess overland flow, whereas most low flow is produced by through flow from 1 to 5 cm depth. Topography and preferential flow paths are important controls on the spatial pattern of runoff even on low‐gradient peat. On steeper midslope regions, more flow occurs within the upper 10 cm of peat rather than at the surface. Preferential flow paths are identified at both the hillslope and plot scale. Discharge deep within the peat is only produced from small macropore and pipe outlets that are well connected to the peat surface. Response to rainfall from these macropore networks is rapid, and they generate around 10% of streamflow.
Salinity impact on water flow and lake ice in Lake Vostok, Antarctica
Authors: Mayer C. , Grosfeld K. , Siegert M. J.
Published: July 2003

Lake Vostok, isolated from direct exchange with the atmosphere for millions of years, provides a unique, so far inaccessible habitat. By using a numerical model, and recent geometry information, the lake circulation was investigated for different salinites. For freshwater, thermally driven circulation occurs, resulting from pressure‐dependent melting point differences at the inclined ice ceiling. North to south ice pumping provides a steady supply of glacial water. The weak circulation is driven by very small density contrasts, but requires no unusual geothermal input. For low salinity conditions, however, circulation intensifies, occupying the entire lake. The maximum amplitudes of melting/freezing increase by about 50% and melting extends further south. For both conditions approximately 200 m of refrozen ice accumulates beneath Vostok Station. The lake habitat will be affected clearly by salinity. It is essential to establish the specific chemistry for comprehending this unique environment and planning in situ experiments.
Delayed onset of the 2002 Indian monsoon
Authors: Flatau M. K. , Flatau P. J. , Schmidt J. , Kiladis G. N.
Published: July 2003

We show that there is a set of dynamical predictors, which facilitate forecasting of a delayed monsoon onset. The main dynamical contributor is the early May propagation of the “bogus onset Intraseasonal Oscillation” which triggers a set of events precluding the climatological monsoon onset. We analyze in detail the 2002 monsoon onset and show that it followed a pattern described in our previous study. We notice that the 2003 monsoon onset followed very similar pattern and was delayed.
Long time memory in global warming simulations
Authors: Blender Richard , Fraedrich Klaus
Published: July 2003

Global power law scaling of near surface temperature spectra is determined in two scenario simulations and in NCEP re‐analyses. The simulations use the coupled atmosphere‐ocean models HadCM3 and ECHAM4/OPYC with greenhouse gas increase according to scenario IS92a in 1860–2099. Observations show a low‐frequency power spectrum S(f) ∼ 1/f over the oceans, a white spectrum in the inner continents, and S(f) ∼ f−0.3 in the coastal areas. The global distribution of the power law exponents is reproduced in the two simulations even in the 21st century with a pronounced temperature increase.