bluuebunny/crossref_metadata_2025 huggingface dataset:
Genomotyping of Pseudomonas putida strains using P. putida KT2440-based high-density DNA microarrays: implications for transcriptomics studies
Authors: Ballerstedt Hendrik , Volkers Rita J. M. , Mars Astrid E. , Hallsworth John E. , Santos Vitor A. Martins dos , Puchalka Jaçek , van Duuren Joost , Eggink Gerrit , Timmis Ken N. , de Bont Jan A. M. , Wery Jan
Published: March 2007

Pseudomonas putida KT2440 is the only fully sequenced P. putida strain. Thus, for transcriptomics and proteomics studies with other P. putida strains, the P. putida KT2440 genomic database serves as standard reference. The utility of KT2440 whole-genome, high-density oligonucleotide microarrays for transcriptomics studies of other Pseudomonas strains was investigated. To this end, microarray hybridizations were performed with genomic DNAs of subcultures of P. putida KT2440 (DSM6125), the type strain (DSM291T), plasmid pWW0-containing KT2440-derivative strain mt-2 (DSM3931), the solvent-tolerant P. putida S12, and several other Pseudomonas strains. Depending on the strain tested, 22 to 99% of all genetic elements were identified in the genomic DNAs. The efficacy of these microarrays to study cellular function was determined for all strains included in the study. The vast majority of DSM6125 genes encoding proteins of primary metabolism and genes involved in the catabolism of aromatic compounds were identified in the genomic DNA of strain S12: a prerequisite for reliable transcriptomics analyses. The genomotypic comparisons between Pseudomonas strains were used to construct highly discriminative phylogenetic relationships. DSM6125 and DSM3931 were indistinguishable and clustered together with strain S12 in a separate group, distinct from DSM291T. Pseudomonas monteilii (DSM14164) clustered well with P. putida strains.
Effects of fragmentation on parasite burden (nematodes) of generalist and specialist small mammal species in secondary forest fragments of the coastal Atlantic Forest, Brazil
Authors: Püttker Thomas , Meyer‐Lucht Yvonne , Sommer Simone
Published: March 2007

Parasites are considered to play an important role in the regulation of wild animal populations. We investigated parasite burden of gastrointestinal nematodes and body condition in specialist and generalist small mammal species in secondary forest fragments in the highly endangered coastal Atlantic Forest. We hypothesized that body condition decreases with increasing parasite load and that parasite burden increases with increasing fragmentation in specialist species but not in generalist species as a consequence of differing responses to fragmentation effects. Investigated species were Akodon montensis, Oligoryzomys nigripes, and Delomys sublineatus (rodents) and the marsupials Marmosops incanus and Gracilinanus microtarsus. Prevalence of parasites was high in all species except for the arboreal G. microtarsus, presumably because of decreased infection probability. No correlation was found between body condition and parasite load in any of the species. Contrary to our expectations, body condition of the specialists D. sublineatus and M. incanus increased in both species with increasing fragmentation. In D. sublineatus, parasite burden increased and body condition decreased in fragments with relatively high density probably due to increased contact rates and facilitation of infection with nematodes. In all generalist species, low or no correlation between parasite burden and fragmentation was detected, suggesting little effect of fragmentation on population health.
Different obscurin isoforms localize to distinct sites at sarcomeres
Authors: Bowman Amber L. , Kontrogianni-Konstantopoulos Aikaterini , Hirsch Sara S. , Geisler Sarah B. , Gonzalez-Serratos Hugo , Russell Mark W. , Bloch Robert J.
Published: March 2007

We used four antibodies to regions of obscurin isoforms A and B, encoded by the obscurin gene, to investigate the location of these proteins in skeletal myofibers at resting and stretched lengths. Obscurin A (∼800 kDa) which was recognized by antibodies generated to the N‐terminal, Rho‐GEF, and the non‐modular C‐terminal domain that lacks the kinase‐like domains, localizes at the level of the M‐band. Obscurin B (∼900 kDa) which has the N‐terminal, Rho‐GEF, and the C‐terminal kinase‐like domains, localizes at the level of the A/I junction. Additional isoforms, which lack one or more of these epitopes, are present at the Z‐disk and Z/I junction.
An electron paramagnetic resonance investigation of the electron transfer reactions in the chlorophyll d containing photosystem I of Acaryochloris marina
Authors: Santabarbara Stefano , Chen Min , Larkum Anthony W.D. , Evans Michael C.W.
Published: March 2007

Electron paramagnetic resonance (EPR) spectroscopy reveals functional and structural similarities between the reaction centres of the chlorophyll d‐binding photosystem I (PS I) and chlorophyll a‐binding PS I. Continuous wave EPR spectrometry at 12 K identifies iron–sulphur centres as terminal electron acceptors of chlorophyll d‐binding PS I. A transient light‐induced electron spin echo (ESE) signal indicates the presence of a quinone as the secondary electron acceptor (Q) between and the iron–sulphur centres. The distance between and Q− was estimated within point‐dipole approximation as 25.23 ± 0.05 Å, by the analysis of the electron spin echo envelope modulation.
The monosaccharide transporter(‐like) gene family in Arabidopsis
Authors: Büttner Michael
Published: March 2007

The availability of complete plant genomes has greatly influenced the identification and analysis of phylogenetically related gene clusters. In Arabidopsis, this has revealed the existence of a monosaccharide transporter(‐like) gene family with 53 members, which play a role in long‐distance sugar partitioning or sub‐cellular sugar distribution and catalyze the transport of hexoses, but also polyols and in one case also pentoses and tetroses. An update on the currently available information on these Arabidopsis monosaccharide transporters, on their sub‐cellular localization and physiological function will be given.
Conformational changes of coat proteins during vesicle formation
Authors: Langer Julian D. , Stoops Emily H. , Béthune Julien , Wieland Felix T.
Published: March 2007

In coated vesicle formation, coat protein recruitment needs to be spatially and temporally controlled. The coating process involves conformational changes of the coat protein complexes that activate them for interaction with cargo or machinery components and coat polymerization. Here we discuss mechanisms that have emerged recently from studies of the clathrin adaptor and the COPI systems.
Proteophosphoglycan is differentially expressed in sodium stibogluconate-sensitive and resistant Indian clinical isolates ofLeishmania donovani
Authors: SAMANT M. , SAHASRABUDDHE A. A. , SINGH N. , GUPTA S. K. , SUNDAR S. , DUBE A.
Published: March 2007

Leishmaniaproduce several types of mucin-like glycoproteins called proteophosphoglycans (PPGs) some of which are secreted while others are found on the surface of promastigotes and amastigotes. These proteins are thought to be important in the transmission, invasion and subsequent intracellular survival of parasites. The structure and function of PPGs are species and stage-specific in the case ofL.majorandL. mexicana, but no such information has hitherto been available forL. donovani. This study presents, for the first time, an initial characterization (localization) of PPG in sodium stibogluconate (SSG)-resistant and sensitive clinical isolates ofL. donovanifrom Bihar (India) by confocal microscopy, flow cytometry and Western blotting using antibodies toL. majorPPG. Confocal microscopy analysis revealed that both promastigotes and amastigotes possess PPG on their cell membrane and flagellar pocket membrane but its expression was variable in different isolates. The quantitative analysis by FACS and Western blotting showed that the expression and intensity of PPG bands was higher in SSG-resistant isolates. This study suggests the possibilities of involvement of PPG in drug-resistant mechanisms and of using PPG abundance as a marker for identifying drug-resistant clinical isolates in Indian kala azar.
A model to account for the consequences of host nutrition on the outcome of gastrointestinal parasitism in sheep: logic and concepts
Authors: VAGENAS D. , BISHOP S. C. , KYRIAZAKIS I.
Published: March 2007

A deterministic, dynamic simulation model is developed to account for the interactions between gastrointestinal parasitism and host nutrition, and predict their consequences on performance and level of parasitism of sheep. Larval intake and established adult worms are assumed to result in nutrient loss for the host. In order to reduce this loss the host will mount an immune response, which will affect the establishment rate of incoming larvae, mortality rate of adult worms, and fecundity of female worms, as well as nutrient loss caused by larval intakeper se. Host anorexia is modelled as a function of worm mass. Parasitism is also assumed to affect the allocation of ingested nutrients to the host's bodily functions, with maintenance getting absolute priority, and protein allocated to immunity and production proportionally to their requirements. Inputs to the model include the expected growth attributes of the animal, feed quality, various parasitological parameters and daily larval intake. Outputs include feed intake, growth rate and body composition, as well as worm burden and faecal egg counts. The model allows exploration of the consequences of gastrointestinal parasitism on sheep of different growth characteristics, kept under environments that vary in the provision of nutrients and exposure to parasites.
Bureaucracy Meets the Environment: Elite Perceptions in Six Chinese Cities
Authors: Tong Yanqi
Published: March 2007

A survey of local government officials and enterprise managers in six Chinese cities demonstrates relatively high environmental awareness. However, this awareness remains primarily an abstraction and does not always shape specific policy preferences. This article shows that the development-driven model works well overall, indicating the reluctance of policy makers to implement environmental protection policies at the cost of sacrificing the rate of economic growth. The pollution-driven model applies only to more developed areas, in which elites in more polluted cities are more concerned about environmental protection than those in less polluted cities. A non-linear model that takes into account the interaction between pollution and development works the best in explaining elites' policy preferences. It suggests that pollution becomes a significant factor affecting policy preferences only when a certain development level is reached.
Vapour is the principal source of water imbibed by seeds in unsaturated soils
Authors: Wuest Stewart
Published: March 2007

The assumption that seeds imbibe most of the water required for germination as liquid through seed-to-soil contact has been a dominant theme in germination research and seeding technology. Under most conditions, seeds are also exposed to water vapour during imbibition, but the relative contributions of liquid and vapour are difficult to assess. In water uptake models that include vapour, procedures used to estimate potential vapour imbibition have underappreciated the effect of distance on diffusion rate. At the same time, the amount of seed-to-soil contact and the liquid bridge from soil water to the seed tend to be greatly overestimated, considering the soil water contents often found in the field. Most researchers have recorded an approximately equal time to germination at soil water contents ranging from field capacity to nearly permanent wilting point, and little response to bulk density, soil type or seed–soil contact. While hydraulic conductivity decreases by several orders of magnitude as soil water content, bulk density and seed-contact decrease, relative humidity remains near 100%. There are several experiments demonstrating timely germination in water vapour alone. The combined evidence contradicts the assumption that seed–soil contact is important for imbibition of water by seeds. Water vapour should be considered the primary source of water for seeds in unsaturated soils.
A revision of Martin's seed classification system, with particular reference to his dwarf-seed type
Authors: Baskin Carol C. , Baskin Jerry M.
Published: March 2007

Martin's (1946) seed classification system has 10 types based on embryo and endosperm characteristics and two additional types based on seed size: dwarf (0.3–2.0 mm) and micro ( ≤ 0.2 mm). He listed 17 families and 12 genera (in five other families) as having dwarf seeds. Our recent discovery of morphophysiological dormancy in dwarf seeds of several taxa ofCampanulaceaeand one ofGentianaceaeprompted an evaluation of dwarf seeds. Martin's paper contains 37 families with one to several small (0.3–2.0 mm) seeded species that he did not list as being dwarf. Comparison of Martin's dwarf families and the 37 small-seeded non-dwarf families revealed no consistent differences between the two groups in endosperm texture, seed-coat anatomy, embryo morphology, class of seed dormancy or phylogenetic position. Also, Martin's dwarf seeds include a variety of embryo morphologies. Consequently, we have revised Martin's key to seed types. The dwarf category has been removed and the micro category replaced by ‘undifferentiated’ to reflect the state of the embryo in fresh seeds. Further, the key now includes linear fully developed, linear underdeveloped, spatulate fully developed and spatulate underdeveloped seed types, which Martin illustrated but did not include in his key. In the revised key, all seeds are distinguished on the basis of embryo and endosperm characteristics.
A new procedure for making observations of embryo morphology in dust-like seeds with rigid coats
Authors: de Vega Clara , de Oliveira Renata Carmo
Published: March 2007

Observing the embryo in dust-like seeds with a rigid coat presents a particular challenge, because it is not possible to use conventional techniques applied to normal-sized seeds. A new combination of softening and clearing techniques, which is remarkably effective for direct observations of embryos in minute seeds, is reported here. Moreover, no special seed treatment is required prior to application of this combination of techniques, and good results are obtained from living and preserved material. Dust-like seeds ofCytinus hypocistisandCytinus ruberwith a rigid coat were treated successively with Franklin's and with Jeffrey's softening fluids, and then with Herr's clearing fluid. The combined action of the two softening fluids caused sufficient seed coat rupture to allow Herr's fluid to clear seed tissues, permitting effective observation of the embryo. This technique should be applicable to a wide range of species with dust-like seeds, and its possibilities for biological studies are numerous.
Age-related biochemical changes during storage of beech (Fagus sylvatica L.) seeds
Authors: Pukacka Stanislawa , Ratajczak Ewelina
Published: March 2007

Substances that could play a role in maintaining seed viability (phenolic compounds, α-tocopherol, sterols, ascorbic acid, glutathione and soluble proteins) were estimated in beech (Fagus sylvatica L.) seed lots that had been stored for 2, 5, 7 and 10 years at − 10°C. Germination capacity was strongly and positively correlated with amounts of total phenolic compounds, ultraviolet (UV)-absorbing phenols and soluble proteins. Moderately strong relationships appeared between germination capacity and α-tocopherol and ascorbic acid contents. Total sterol and glutathione contents were not correlated with germination capacity. A strong, negative correlation was found between germination capacity and reactive oxygen species (ROS), such as superoxide radical (O _{2}^{\cdot - }) and hydrogen peroxide (H2O2), as well as with lipid hydroxyperoxides (LHPOs). The putative role of these compounds in the maintenance of beech seed viability during long-term storage is discussed.
Ältere Suchtkranke im psychiatrischen Krankenhaus
Authors: Wetterling Tilman , Kugler Christof
Published: March 2007

Zusammenfassung: Suchterkrankungen gehören mit zu den häufigsten chronischen Erkrankungen in Deutschland. Aufgrund der steigenden Lebenserwartung stellt sich die Frage, wie häufig Suchterkrankungen bei älteren Patienten sind. Zu diesem Themenbereich existieren bisher kaum Studien aus Deutschland. In dieser Studie wurden die Krankenhausdaten 2003-2005 von den sieben psychiatrischen Kliniken der Vivantes GmbH, Berlin (Versorgungsgebiet: etwa 1.6 Millionen Einw.) ausgewertet. Bei 50.7 % der insgesamt 46911 erfassten Fällen wurde eine substanzbedingte Störung (ICD-10: F1) als Haupt- oder Nebendiagnose gestellt. Nur 22.3 % der Aufnahmen über 65 Jahre, aber 52.7 % der Unter-65-Jährigen hatten eine substanzbedingte Störung. Ganz überwiegend handelte es sich um einen Alkoholmissbrauch bzw. eine Alkoholabhängigkeit. Der Anteil der Fälle mit neuropsychiatrischen Komplikationen stieg mit dem Alter an. Die Ergebnisse zeigen, dass auch unter den älteren psychiatrischen Patienten ein relevanter Anteil eine Suchtproblematik hat und neuropsychiatrische Komplikationen häufig sind.
Diagnostik von alkoholbezogenen Störungen im Alter
Authors: Rumpf Hans-Jürgen
Published: March 2007

Zusammenfassung: Der Beitrag gibt einen Überblick zur Diagnostik von problematischem Alkoholkonsum im Alter. Dabei wird unterschieden zwischen riskantem Konsum, Alkoholabhängigkeit und -missbrauch. Es werden Screeningverfahren auf ihre Anwendbarkeit in der Gruppe der älteren Menschen überprüft und spezifische Verfahren vorgestellt. Zum Teil sind Modifikationen möglich und notwendig. Das gilt z. B. für den häufig eingesetzten CAGE, bei dem das Herabsetzten des Cut-off notwendig ist. Zur Erfassung der Trinkmengen kann auf bewährte Verfahren wie Q/F-Index oder Timeline-Follow-Back zurück gegriffen werden, es können jedoch spezifische Hilfen sinnvoll sein. Bei den Kriterien für Abhängigkeit und Missbrauch gelten zum Teil Besonderheiten, das gilt u. a. bei der Beurteilung von Toleranzentwicklung und Entzugserscheinungen. Dieses ist beim Einsatz von strukturierten oder standardisierten Interviewverfahren zu berücksichtigen.
Alkohol-assoziierte kognitive Beeinträchtigungen
Authors: Wolter Dirk K.
Published: March 2007

Zusammenfassung: Alkoholmissbrauch kann in vielfältiger Weise zu kognitiven Defiziten beitragen, die von diskreten Beeinträchtigungen bis zu schweren demenziellen Syndromen reichen und zumindest partiell reversibel aber auch dauerhaft sein können. Dauerhafte kognitive Defizite allein aufgrund einer unmittelbaren neurotoxischen Wirkung des thanol sind sehr selten; sie sind meist mit neurologischen oder internistischen Alkoholfolgekrankheiten assoziiert bzw. der Alkohol wirkt als Kofaktor. Die neurobiologischen Korrelate sind nicht sehr spezifisch. Verschiedene pathogenetische Mechanismen werden diskutiert, die aus der Perspektive der Neurogenese besser verständlich werden. Eine besondere Rolle spielt das Korsakoff-Syndrom, wobei überkommene Vorstellungen zum Wernicke-Korsakoff-Komplex wahrscheinlich revidiert werden müssen. Nur Alkoholmissbrauch erhöht das Demenzrisiko, während moderater Alkoholkonsum mit einem gegenüber Abstinenz verminderten Risiko einhergeht. Der Terminus “Alkohol-assoziierte kognitive Beeinträchtigungen” (“alcohol-related cognitive impairment”) erscheint als übergeordnete Bezeichnung zweckmäßig. Gesicherte Erkenntnisse über symptomatische Therapiemöglichkeiten liegen nicht vor.
Abhängigkeitserkrankungen im Alter
Authors: Voßmann Ulrich , Geyer Dieter
Published: March 2007

Zusammenfassung: Sucht im Alter verläuft in der Regel mehr im Verborgenen, wird häufig nicht wahrgenommen oder verharmlost. Psychosoziale Faktoren wie Altersstress, Hilflosigkeit, Depressionen, Vereinsamung und Verlusterlebnisse begünstigen eine Suchtentwicklung im höheren Lebensalter. Bei entsprechender Motivation und Behandlung in altersentsprechenden Seniorengruppen sind die Erfolgsaussichten wesentlich günstiger als allgemein angenommen. Anhand des Therapiekonzeptes der Fachklinik Fredeburg werden die therapeutisch-praktischen Erfahrungen und Behandlungsergebnisse dargestellt.
Alkoholmissbrauch und -abhängigkeit bei Bewohnern und Bewohnerinnen in Altenpflegeheimen
Authors: Weyerer Siegfried , Schäufele Martina , Hendlmeier Ingrid
Published: March 2007

Zusammenfassung: Im Vergleich zu älteren Menschen in Privathaushalten ist der Anteil Alkoholkranker in Altenpflegeheimen überdurchschnittlich hoch. 1995/96, 1997/98 und 2002/03 in 13 Mannheimer Altenpflegeheimen (bei jeweils über 1200 Bewohnern und Bewohnerinnen) durchgeführte Querschnittsstudien ergaben, dass zu allen drei Zeitpunkten etwa 10 % der Bewohnerschaft eine ärztliche Alkoholdiagnose nach ICD 10 aufwiesen. Dabei waren - ebenfalls stabil über die Zeit - ein Viertel der Männer und 5 % der Frauen betroffen. Zu allen drei Querschnitten zeigten die Bewohner, die bei Heimeintritt eine Alkoholdiagnose hatten, im Vergleich zu den Bewohnern und Bewohnerinnen ohne Alkoholdiagnose signifikante Unterschiede bei einer Reihe von Merkmalen: Das Alter zum Zeitpunkt des Heimeintritts war bei Alkoholkranken mit 62 Jahren wesentlich niedriger im Vergleich zu Nichtalkoholkranken (78 Jahre). Über die Hälfte der Alkoholkranken, aber nur jeder vierte Nichtalkoholkranke war ledig oder geschieden. Vermutlich auch aufgrund des kleineren sozialen Netzes erhielten Alkoholkranke signifikant seltener Besuch von Verwandten und Angehörigen. Verglichen mit den ärztlichen Alkoholdiagnosen bei Heimeintritt ist die Prävalenz des aktuell von den Pflegekräften eingeschätzten Alkoholmissbrauchs mit 4,2 % (1995/96), 5.2 % (1997/98) und 2.2 % (2002/03) wesentlich niedriger. Alkoholkranke stellen eine besondere Herausforderung für die Pflegekräfte dar: Die Hälfte der Bewohner und Bewohnerinnen mit aktuellem Alkoholmissbrauch zeigte ein aggressives Verhalten und unkooperatives Verhalten gegenüber dem Pflegepersonal; bei der Gruppe ohne Alkoholmissbrauch traten diese Probleme dagegen nur bei etwa 25 % auf. Auf die Anforderungen von Alkoholkranken sind die Pflegekräfte nur unzureichend vorbereitet. Eine Schulung des Pflegepersonals im Umgang mit Alkoholkranken, eine adäquate personelle Ausstattung sowie eine konsiliarische Beratung durch qualifizierte Mitarbeiter und Mitarbeiterinnen von Suchtberatungsstellen sind dringend erforderlich.
A joint atmosphere‐ocean inversion for surface fluxes of carbon dioxide: 1. Methods and global‐scale fluxes
Authors: Jacobson Andrew R. , Mikaloff Fletcher Sara E. , Gruber Nicolas , Sarmiento Jorge L. , Gloor Manuel
Published: March 2007

We have constructed an inverse estimate of surface fluxes of carbon dioxide using both atmospheric and oceanic observational constraints. This global estimate is spatially resolved into 11 land regions and 11 ocean regions, and is calculated as a temporal mean for the period 1992–1996. The method interprets in situ observations of carbon dioxide concentration in the ocean and atmosphere with transport estimates from global circulation models. Uncertainty in the modeled circulation is explicitly considered in this inversion by using a suite of 16 atmospheric and 10 oceanic transport simulations. The inversion analysis, coupled with estimates of river carbon delivery, indicates that the open ocean had a net carbon uptake from the atmosphere during the period 1992–96 of 1.7 PgC yr−1, consisting of an uptake of 2.1 PgC yr−1 of anthropogenic carbon and a natural outgassing of about 0.5 PgC yr−1 of carbon fixed on land and transported through rivers to the open ocean. The formal uncertainty on this oceanic uptake, despite a comprehensive effort to quantify sources of error due to modeling biases, uncertain riverine carbon load, and biogeochemical assumptions, is driven down to 0.2 PgC yr−1 by the large number and relatively even spatial distribution of oceanic observations used. Other sources of error, for which quantifiable estimates are not currently available, such as unresolved transport and large region inversion bias, may increase this uncertainty.
A joint atmosphere‐ocean inversion for surface fluxes of carbon dioxide: 2. Regional results
Authors: Jacobson Andrew R. , Mikaloff Fletcher Sara E. , Gruber Nicolas , Sarmiento Jorge L. , Gloor Manuel
Published: March 2007

We report here the results from a coupled ocean‐atmosphere inversion, in which atmospheric CO2 gradients and transport simulations are combined with observations of ocean interior carbon concentrations and ocean transport simulations to provide a jointly constrained estimate of air‐sea and air‐land carbon fluxes. While atmospheric data have little impact on regional air‐sea flux estimates, the inclusion of ocean data drives a substantial change in terrestrial flux estimates. Our results indicate that the tropical and southern land regions together are a large source of carbon, with a 77% probability that their aggregate source size exceeds 1 PgC yr−1. This value is of similar magnitude to estimates of fluxes in the tropics due to land‐use change alone, making the existence of a large tropical CO2 fertilization sink unlikely. This terrestrial result is strongly driven by oceanic inversion results that differ from flux estimates based on ΔpCO2 climatologies, including a relatively small Southern Ocean sink (south of 44°S) and a relatively large sink in the southern temperate latitudes (44°S–18°S). These conclusions are based on a formal error analysis of the results, which includes uncertainties due to observational error transport and other modeling errors, and biogeochemical assumptions. A suite of sensitivity tests shows that these results are generally robust, but they remain subject to potential sources of unquantified error stemming from the use of large inversion regions and transport biases common to the suite of available transport models.
Air‐sea exchange in the global mercury cycle
Authors: Strode Sarah A. , Jaeglé Lyatt , Selin Noelle E. , Jacob Daniel J. , Park Rokjin J. , Yantosca Robert M. , Mason Robert P. , Slemr Franz
Published: March 2007

We present results from a new global atmospheric mercury model coupled with a mixed layer slab ocean. The ocean model describes the interactions of the mixed layer with the atmosphere and deep ocean, as well as conversion between elemental, divalent, and nonreactive mercury species. Our global mean aqueous concentrations of 0.07 pM elemental, 0.80 pM reactive, and 1.51 pM total mercury agree with observations. The ocean provides a 14.1 Mmol yr−1 source of mercury to the atmosphere, at the upper end of previous estimates. Re‐emission of previously deposited mercury constitutes 89% of this flux. Ocean emissions are largest in the tropics and downwind of industrial regions. Midlatitude ocean emissions display a large seasonal cycle induced by biological productivity. Oceans contribute 54% (36%) of surface atmospheric mercury in the Southern (Northern) Hemisphere. We find a large net loss of mercury to the deep ocean (8.7 Mmol yr−1), implying a ∼0.7%/year increase in deep ocean concentrations.
High‐voltage antenna‐plasma interaction in whistler wave transmission: Plasma sheath effects
Authors: Song P. , Reinisch B. W. , Paznukhov V. , Sales G. , Cooke D. , Tu J.‐N. , Huang X. , Bibl K. , Galkin I.
Published: March 2007

We study the plasma sheath surrounding an antenna that transmits whistler mode waves in the inner magnetosphere in order to investigate the feasibility of conducting controlled experiments on the role of wave‐particle interactions in the pitch angle diffusion of relativistic radiation belt electrons. We propose a model for an electrically short antenna‐sheath‐plasma system with transmission frequencies below the electron characteristic frequencies and much higher than the ion characteristic frequencies. The ion current is neglected. We analytically solve a time‐dependent one‐dimensional situation by neglecting the effects of the wave's magnetic field. In our model, the antenna is charged to a large negative potential during a steady transmission. Positive charge occurs in the sheath and the sheath is free of electrons and conduction current. The net charge on the antenna and in the sheath is zero. The volume, or the radius in a cylindrical case, of the sheath varies in response to the charge/voltage variation on the antenna. The oscillating radius of the sheath translates to a current in the plasma, which radiates waves into the plasma. A whistler wave transmission experiment conducted by the RPI‐IMAGE has shown that the model may describe the most important physical processes occurring in the system. The system response is predominately reactive, showing no evidence for significant sheath current or sheath resistance. The negligibly small sheath conduction electron current can be understood if the antenna is charged to a substantial negative potential, as described by the model. Quantitatively, the model may underestimate the sheath capacitance by about 20%.
Geodetic, teleseismic, and strong motion constraints on slip from recent southern Peru subduction zone earthquakes
Authors: Pritchard M. E. , Norabuena E. O. , Ji C. , Boroschek R. , Comte D. , Simons M. , Dixon T. H. , Rosen P. A.
Published: March 2007

We use seismic and geodetic data both jointly and separately to constrain coseismic slip from the 12 November 1996 Mw 7.7 and 23 June 2001 Mw 8.5 southern Peru subduction zone earthquakes, as well as two large aftershocks following the 2001 earthquake on 26 June and 7 July 2001. We use all available data in our inversions: GPS, interferometric synthetic aperture radar (InSAR) from the ERS‐1, ERS‐2, JERS, and RADARSAT‐1 satellites, and seismic data from teleseismic and strong motion stations. Our two‐dimensional slip models derived from only teleseismic body waves from South American subduction zone earthquakes with Mw > 7.5 do not reliably predict available geodetic data. In particular, we find significant differences in the distribution of slip for the 2001 earthquake from models that use only seismic (teleseismic and two strong motion stations) or geodetic (InSAR and GPS) data. The differences might be related to postseismic deformation or, more likely, the different sensitivities of the teleseismic and geodetic data to coseismic rupture properties. The earthquakes studied here follow the pattern of earthquake directivity along the coast of western South America, north of 5°S, earthquakes rupture to the north; south of about 12°S, directivity is southerly; and in between, earthquakes are bilateral. The predicted deformation at the Arequipa GPS station from the seismic‐only slip model for the 7 July 2001 aftershock is not consistent with significant preseismic motion.
Seismicity rate immediately before and after main shock rupture from high‐frequency waveforms in Japan
Authors: Peng Zhigang , Vidale John E. , Ishii Miaki , Helmstetter Agnes
Published: March 2007

We analyze seismicity rate immediately before and after 82 main shocks with the magnitudes ranging from 3 to 5 using waveforms recorded by the Hi‐net borehole array in Japan. By scrutinizing high‐frequency signals, we detect ∼5 times as many aftershocks in the first 200 s as in the Japan Meteorological Agency catalogue. After correcting for the changing completeness level immediately after the main shock, the aftershock rate shows a crossover from a slower decay with an Omori's law exponent p = 0.58 ± 0.08 between 20 and 900 s after the main shock to a faster decay with p = 0.92 ± 0.04 after 900 s. The foreshock seismicity rate follows an inverse Omori's law with p = 0.73 ± 0.08 from several tens of days up to several hundred seconds before the main shock. The seismicity rate in the 200 s immediately before the main shock appears steady with p = 0.35 ± 0.50. These observations can be explained by the epidemic‐type aftershock sequence (ETAS) model, and the rate‐and‐state model for a heterogeneous stress field on the main shock rupture plane. Alternatively, nonseismic stress changes near the source region, such as episodic aseismic slip, or pore fluid pressure fluctuations, may be invoked to explain the observation of small p values immediately before and after the main shock.
An evaluation of submarine groundwater discharge along the continental shelf of Louisiana using a multiple tracer approach
Authors: McCoy Clayton A. , Corbett D. Reide , McKee Brent A. , Top Zafer
Published: March 2007

Natural geochemical tracers (222Rn, 3H, 3He, and 4He) were used to assess submarine groundwater discharge (SGD) along the continental shelf west of the Mississippi River. In order to assess SGD, groundwater, surface water, and sediment samples were collected on land and during six 4‐day cruises aboard the R/V Pelican between March 2003 and May 2004. A box model approach was used to quantify sources and sinks of 222Rn in the study area and to calculate SGD rates. SGD estimates were we based on two end member values for the potential advecting fluids: (1) that supported by 226Ra in the sediments; and (2) groundwater activities measured in monitoring wells. Calculated 222Rn SGD rates based on sediment supported activities ranged from 0.04 to 0.14 cm d−1, and estimates based on monitoring well activities ranged from 0.01 to 0.07 cm d−1 and corresponds to 1.41 km3 yr−1 of discharged water over our study area, equivalent to <1% of the Mississippi River during the same time frame. 3He and 4He, longer‐lived tracers, exhibited significantly greater anomalies in the eastern portion of the study area which corresponds with greater oil and gas extraction and the release of formation water into the water column in this region. While the total SGD was relatively minor, potential sources of SGD are many and we suggest formation water associated with oil and gas extraction, geothermal convection, and seawater recirculation are the primary sources with a minimal contribution from terrestrially derived topography driven flow.
Hydrogeological modeling of submarine groundwater discharge on the continental shelf of Louisiana
Authors: Thompson Craig , Smith Leslie , Maji Roudrajit
Published: March 2007

A regional scale hydrogeologic model has been developed to estimate the magnitude of submarine groundwater discharge to the coastal waters of southeastern Louisiana. The model domain incorporates both the onshore recharge area of terrestrially derived freshwater, and fluid circulation within the sediments on the continental shelf. The hydrogeologic properties of these sediments, which form part of the Coastal Lowlands Aquifer System, have been well‐characterized in earlier studies. The low topographic relief of the coastal plain and an extensive zone of seawater intrusion are key features of the groundwater flow system. Model calculations suggest that no water containing a substantial component of terrestrial origin discharges on the continental shelf. Rather the near‐shore coastal zone serves as a groundwater recharge area of saline water that then forms the seawater recirculation system beneath the coastal plain. The modeling results are consistent with interpretations of the rates of submarine groundwater discharge derived from geochemical tracers, presented in a companion paper by McCoy et al. (2007).
Decadal variations and trends in tropical Pacific sea surface salinity since 1970
Authors: Delcroix Thierry , Cravatte Sophie , McPhaden Michael J.
Published: March 2007

The dominant mode of variability in the tropical Pacific is the interannual El Niño–Southern Oscillation phenomenon. More subtle variations are also evident on decadal timescales reminiscent of the Pacific Decadal Oscillation (PDO). These variations are superimposed on trends that are possibly linked to global climate change. A major impediment for assessing this decadal and longer timescale variability is the shortness of instrumental records. Near‐surface salinity has not yet been systematically analyzed for this reason. This article documents and interprets 1970–2003 observed tropical Pacific sea surface salinity (SSS) changes. Given the time/space SSS data availability, the analysis focuses on changes in three key regions, the western Pacific Warm Pool (WP), the South Pacific Convergence Zone (SPCZ), and the Equatorial Cold Tongue (ECT). A PDO‐like signal shows up in these three regions, with some shifts in SSS appearing around the mid‐1970s, mid‐1990s, and to a lesser extent in 1989–1990. In addition, a clear freshening trend of the order of 0.1 to 0.3 psu per 30 years appears in the WP, SPCZ, and ECT, together with an extension of the low‐salinity water surface in the WP and SPCZ. On the basis of available precipitation (P) and evaporation (E) products, and on a survey of the published literature, the PDO‐like SSS changes are found to be qualitatively consistent with P and E and/or horizontal and vertical salt advection in the WP and the SPCZ. The repercussions and unsolved issues regarding the SSS decadal changes and freshening trends are discussed.
An assessment of Multiangle Imaging Spectroradiometer (MISR) stereo‐derived cloud top heights and cloud top winds using ground‐based radar, lidar, and microwave radiometers
Authors: Marchand Roger T. , Ackerman Thomas P. , Moroney Catherine
Published: March 2007

In this article stereoscopically derived cloud top heights and cloud winds estimated from the Multiangle Imaging Spectroradiometer (MISR) are assessed. MISR is one of five instruments on board the NASA Terra satellite. The cloud top height assessment is based on a comparison of more than 4 years of MISR retrievals with that derived from ground‐based radar and lidar systems operated by the U.S. Department of Energy Atmospheric Radiation Measurement program. The assessment includes a comparison of the MISR cloud top heights and ground‐based data sets as a function of cloud optical depth and a simple cloud classification. Overall, we find that the MISR retrieval is working well with little bias for most cloud types, when the cloud is sufficiently optically thick to be detected. The detection limit is found to be around optical depth 0.3 to 0.5, except over snow and ice surfaces where it is larger. The standard deviation across all clouds is less than about 1000 m for the MISR best winds retrievals at all ARM sites, and the standard deviation for the MISR without winds retrieval varied between about 1000 to 1300 m, depending on the site. The performance for various cloud types is explored.
Statistics of plasma fluxes at geosynchronous orbit over more than a full solar cycle
Authors: Thomsen M. F. , Denton M. H. , Lavraud B. , Bodeau M.
Published: March 2007

The extensive database of plasma measurements from Los Alamos geosynchronous satellites is used to derive a statistical characterization of the geosynchronous fluxes of ions and electrons between the energies of ∼40 eV and ∼45 keV. The database covers more than an entire solar cycle and all levels of geomagnetic activity. The derived flux averages and various percentile levels thus describe the environment to which geosynchronous satellites are exposed over their lifetimes and should provide a useful tool to guide satellite design and testing. The mission‐averaged fluxes agree very well with other recent analyses in the energy ranges of overlap.
Evaluation of a laser technique to isolate the inner cell mass of murine blastocysts
Authors: Cortés José Luis , Cobo Fernando , Catalina Purificación , Nieto Ana , Cabrera Carmen , Montes Rosa , Concha Ángel , Menendez Pablo
Published: March 2007

hESCs (human embryonic stem cells) are pluripotent cells derived from the ICM (inner cell mass) of blastocysts that can be used to derive several kinds of cells of the human body for the treatment of some previously untreated diseases. In considering the future use of hESCs in regenerative medicine and cell‐therapy programmes, several research centres have begun projects involving the derivation of hESC lines using spare human embryos from IVF (in vitro fertilization) cycles. In some stem‐cell banks, such as ours, the law also permits us to obtain these cell lines. The low availability of spare IVF human embryos, and the low rate of success in the derivation of hESC lines, give these embryos a great research value that limits experiments with new techniques. The use of murine embryos would be a good model with which to do research to discover the best methodologies to use in order to derive new hESC lines. The aim of the present study was to evaluate a new method of isolation of the ICM and derivation of ESC lines in a murine blastocyst model using laser drilling to eliminate the trophectoderm cells and compare it with the usual control method consisting of culturing the whole murine blastocyst. We also tested the adhesion and growth of primary colonies of mESCs (murine ESCs) over two different growth surfaces, namely an MEF (inactive murine fibroblastic feeder layer) or gelatin‐coated dishes, in order to achieve the best culture conditions for future derivation of human stem‐cell lines for application in human transplantation.
Enhancement of tanshinone production in Salvia miltiorrhiza Bunge (red or Chinese sage) hairy‐root culture by hyperosmotic stress and yeast elicitor
Authors: Shi Ming , Kwok K. W. , Wu Jian Yong
Published: March 2007

The present study evaluates the use of hyperosmotic stress and a biotic elicitor YE (yeast elicitor; polysaccharide fraction of yeast extract) to stimulate diterpenoid tanshinone production in hairy‐root culture of Salvia miltiorrhiza Bunge (Lamiaceae). Sorbitol was applied as an osmoticum at various concentrations (30–100 g/l) to the hairy‐root culture in MS (Murashige and Skoog) medium [Murashige and Skoog (1962) Physiol. Plant. 15, 473–497] containing 30 g/l sucrose, and it increased the TT (total tanshinone) content of roots most dramatically at 50–70 g/l (medium osmolality 410–500 mmol/kg; 1 mol/kg≈1 osmol/kg), to 4.5‐fold of that in the control. The hairy roots showed strong tolerance to hyperosmotic stress, retaining a stable or higher dry weight of roots at osmolality up to 500 mmol/kg. Most remarkably, the combined use of sorbitol (50 g/l) and YE (100 mg/l) increased the TT content 10‐fold (1481.6 versus 146.4 μg/g dry root) and the volumetric tanshinone yield 9‐fold (16.3 versus 1.77 mg/l) compared with the control. The results suggest that the combined use of hyperosmotic stress and a biotic elicitor can effectively enhance secondary metabolite production in hairy‐root cultures.
A novel PEGylation of chitosan nanoparticles for gene delivery
Authors: Zhang Yanqiong , Chen Jiji , Zhang Yangde , Pan Yifeng , Zhao Jingfeng , Ren Lifeng , Liao Mingmei , Hu Zhiyuan , Kong Lu , Wang Jiwei
Published: March 2007

CS (chitosan) has emerged as a promising non‐viral vector for gene delivery because of its ability to form complexes with pDNA (plasmid DNA) and enhance its transport across cellular membranes through endocytosis. Complexes of CS and pDNA may improve transfection efficiency; however, they are not capable of sustained DNA release and prolonging gene transfer. In order to achieve prolonged delivery of CS–DNA complexes, we prepared CS NP (nanoparticle) and CS–DNA complexes. α‐Methoxy‐ω‐succinimidylpoly(ethylene glycol) was then conjugated to the surface of CS–DNA complexes using an active ester scheme; finally, the potential of PEGylation [poly(ethylene glycol)ylation] of CS NP as a non‐viral gene‐delivery vector to transfer exogenous genes in vitro and in vivo were examined. Electrophoretic analysis suggested that CS NPs could protect the DNA from nuclease degradation. The pDNA carried by CS NPs could enter and be expressed in HepG2 cells. However, the transfection efficiency was very low and the highest dose of DNA transferred was 1.6 μg. The transfection activities of CS–DNA–PEG were preserved and a higher dose (2.4 μg) of pDNA was transferred. This indicated that the transfection efficiency of the PEGylated complexes had been improved. In vivo experiments also showed that CS–DNA–PEG complexes mediated higher gene expression in tissues than did CS–DNA complexes, and that gene expression in tumours induced by CS–DNA–PEG complexes was the highest of all. These results suggested that PEGylation of CS–DNA complexes improves non‐viral gene delivery in vitro or in vivo and has the potential to deliver therapeutic genes directly into hepatoma tissues.
Interaction between colloids with grafted diblock polyampholytes
Authors: Linse Per
Published: March 2007

The interaction between composite colloidal particles composed of a spherical core and grafted AB-diblock polyampholytes (diblock copolymers with oppositely charged blocks) are investigated by using a coarse-grained model solved with Monte Carlo simulations. The B block is end-grafted onto the core of the colloid and its linear charge density is varied, whereas the linear charge density of the A block is fixed. The brush structure of a single colloid, the mean force between two colloids, and the structure of solutions of such colloids have been determined for different linear charge densities of the B blocks and block lengths. Many features of the present system are controlled by the charge of the B blocks. In the limit of uncharged B blocks, (i) the grafted chains are stretched and form an extended polyelectrolyte brush, (ii) a strong repulsive force is operating between two colloids, (iii) and the solution is thermodynamic stable and displays strong spatial correlation among the colloids. In the limit where the charges of the two types of blocks exactly compensate each other, (i) the chains are collapsed and form a polyelectrolyte complex surrounding the cores, (ii) an attractive force appears between two colloids, and (iii) strong colloid clustering appears in the solution. These features become more pronounced as the length of the polymer blocks is increased, and a phase instability occurs at sufficiently long chains. A comparison with properties for other related colloidal particles is also provided.
Skeletal Si–O–Si network connectivity of self-assembled porous silica for low-k dielectrics depending on organoalkoxysilane concentration in precursor solutions
Authors: Takada Syozo , Hata Nobuhiro , Hayamizu Kikuko , Murakami Miwa , Deguchi Kenzo , Ohki Shinobu , Tansho Masataka , Shimizu Tadashi
Published: March 2007

Self-assembled porous silica films prepared from the tetraethoxysilane (TEOS)-based precursor solutions containing dimethyldiethoxysilane (DMDEOS) are known to have higher mechanical strength than the films prepared from TEOS precursor solution not containing DMDEOS. To clarify the origin of their higher mechanical strength, Si29 magic-angle-spinning nuclear magnetic resonance (MAS NMR) spectroscopy was carried out for a series of self-assembled porous silica samples prepared by varying the DMDEOS concentration in the precursor solution. The MAS NMR spectra obtained were analyzed to deduce concentrations of the methyl and hydroxyl functional groups and Si–O–Si bonds, from which the connectivity number m, or the average coordination number, was calculated to assess the skeletal mechanical strength. A maximum of m appeared at the concentration of DMDEOS∕(TEOS+DMDEOS)=0.17. It is concluded that the enhancement of Si–O–Si network formation by the added DMDEOS into the TEOS-based precursor solution is the origin of the improvement of the skeletal mechanical strength.