bluuebunny/crossref_metadata_2025 huggingface dataset:
Dopamine Induces IL-6–Dependent IL-17 Production via D1-Like Receptor on CD4 Naive T Cells and D1-Like Receptor Antagonist SCH-23390 Inhibits Cartilage Destruction in a Human Rheumatoid Arthritis/SCID Mouse Chimera Model
Authors: Nakano Kazuhisa , Yamaoka Kunihiro , Hanami Kentaro , Saito Kazuyoshi , Sasaguri Yasuyuki , Yanagihara Nobuyuki , Tanaka Shinya , Katsuki Ichiro , Matsushita Sho , Tanaka Yoshiya
Published: February 2011

A major neurotransmitter dopamine transmits signals via five different seven-transmembrane G protein-coupled receptors termed D1–D5. Several studies have shown that dopamine not only mediates interactions into the nervous system, but can contribute to the modulation of immunity via receptors expressed on immune cells. We have previously shown an autocrine/paracrine release of dopamine by dendritic cells (DCs) during Ag presentation to naive CD4+ T cells and found efficacious results of a D1-like receptor antagonist SCH-23390 in the experimental autoimmune encephalomyelitis mouse model of multiple sclerosis and in the NOD mouse model of type I diabetes, with inhibition of Th17 response. This study aimed to assess the role of dopaminergic signaling in Th17-mediated immune responses and in the pathogenesis of rheumatoid arthritis (RA). In human naive CD4+ T cells, dopamine increased IL-6–dependent IL-17 production via D1-like receptors, in response to anti-CD3 plus anti-CD28 mAb. Furthermore, dopamine was localized with DCs in the synovial tissue of RA patients and significantly increased in RA synovial fluid. In the RA synovial/SCID mouse chimera model, although a selective D2-like receptor antagonist haloperidol significantly induced accumulation of IL-6+ and IL-17+ T cells with exacerbated cartilage destruction, SCH-23390 strongly suppressed these responses. Taken together, these findings indicate that dopamine released by DCs induces IL-6–Th17 axis and causes aggravation of synovial inflammation of RA, which is the first time, to our knowledge, that actual evidence has shown the pathological relevance of dopaminergic signaling with RA.
Primary Human CD4+ T Cells Have Diverse Levels of Membrane Lipid Order That Correlate with Their Function
Authors: Miguel Laura , Owen Dylan M. , Lim Chrissie , Liebig Christian , Evans Jamie , Magee Anthony I. , Jury Elizabeth C.
Published: February 2011

Membrane lipid microdomains (lipid rafts) play an important role in T cell function by forming areas of high lipid order that facilitate activation. However, their role in regulating T cell differentiation and function remains controversial. In this study, by applying a new approach involving microscopy and flow cytometry, we characterize membrane lipid order in ex vivo primary human CD4+ T cells. We reveal that differential membrane lipid order dictates the response to TCR stimulation. T cells with high membrane order formed stable immune synapses and proliferated robustly, intermediate order cells had reduced proliferative ability accompanied by unstable immune synapse formation, whereas low order T cells were profoundly unresponsive to TCR activation. We also observed that T cells from patients with autoimmune rheumatic disease had expanded intermediate order populations compared with healthy volunteers. This may be important in dictating the nature of the immune response since most IFN-γ+CD4+ T cells were confined within intermediate membrane order populations, whereas IL-4+CD4+ T cells were contained within the high order populations. Importantly, we were able to alter T cell function by pharmacologically manipulating membrane order. Thus, the results presented from this study identify that ex vivo CD4+ T cells sustain a gradient of plasma membrane lipid order that influences their function in terms of proliferation and cytokine production. This could represent a new mechanism to control T cell functional plasticity, raising the possibility that therapeutic targeting of membrane lipid order could direct altered immune cell activation in pathology.
Epigenetic Changes at Il12rb2 and Tbx21 in Relation to Plasticity Behavior of Th17 Cells
Authors: Bending David , Newland Stephen , Krejčí Alena , Phillips Jenny M. , Bray Sarah , Cooke Anne
Published: February 2011

Plasticity within Th cell populations may play a role in enabling site-specific immune responses to infections while limiting tissue destruction. Epigenetic processes are fundamental to such plasticity; however, to date, most investigations have focused on in vitro-generated T cells. In this study, we have examined the molecular mechanisms underpinning murine Th17 plasticity in vivo by assessing H3K4 and H3K27 trimethylation marks at Tbx21, Rorc, Il17a, Ifng, and Il12rb2 loci in purified ex vivo-isolated and in vitro-generated Th17 cells. Although both populations had largely comparable epigenetic signatures, including bivalent marks at Tbx21, freshly isolated ex vivo Th17 cells displayed restricted expression from Il12rb2 due to the presence of repressive chromatin modifications. This receptor, however, could be upregulated on isolated ex vivo Th17 cells after in vitro activation or by in vivo immunization and was augmented by the presence of IFN-γ. Such activated cells could then be deviated toward a Th1-like profile. We show that IL-12 stimulation removes H3K27 trimethylation modifications at Tbx21/T-bet leading to enhanced T-bet expression with in vitro Th17 cells. Our study reveals important potential phenotypic differences between ex vivo- and in vitro-generated Th17 cells and provides mechanistic insight into Th17 cell plasticity.
Cutting Edge: CD8+ T Cell Priming in the Absence of NK Cells Leads to Enhanced Memory Responses
Authors: Soderquest Katrina , Walzer Thierry , Zafirova Biljana , Klavinskis Linda S. , Polić Bojan , Vivier Eric , Lord Graham M. , Martín-Fontecha Alfonso
Published: February 2011

It is uncertain whether NK cells modulate T cell memory differentiation. By using a genetic model that allows the selective depletion of NK cells, we show in this study that NK cells shape CD8+ T cell fate by killing recently activated CD8+ T cells in an NKG2D- and perforin-dependent manner. In the absence of NK cells, the differentiation of CD8+ T cells is strongly biased toward a central memory T cell phenotype. Although, on a per-cell basis, memory CD8+ T cells generated in the presence or the absence of NK cells have similar functional features and recall capabilities, NK cell deletion resulted in a significantly higher number of memory Ag-specific CD8+ T cells, leading to more effective control of tumors carrying model Ags. The enhanced memory responses induced by the transient deletion of NK cells may provide a rational basis for the design of new vaccination strategies.
Coexpression of PPE 34.9 Antigen ofMycobacterium aviumsubsp.Paratuberculosiswith Murine Interferon Gamma in HeLa Cell Line and Study of Their Immunogenicity in Murine Model
Authors: Deb Rajib , Goswami P. P.
Published: February 2011

Mycobacterium aviumsubsp.paratuberculosis(Map) is the causative agent of johne's disease whose immunopathology mainly depends on cell mediated immuneresponse. Genome sequencing revealed various PPE (Proline-Proline-Glutamic acid) protein family of Map which are immunologically importance candidate genes In present study we have developed a bicistrionic construct pIR PPE/IFN containing a 34.9 kDa PPE protein (PPE 34.9) of Map along with a cytokine gene encoding murine gamma Interferon gene (IFNγ) and a monocistrionic construct pIR PPE using a mammalian vector system pIRES 6.1. The construct were transfected in HeLa cell line and expression were studied by Western blot as well as Immunefluroscent assay using recombinant sera. Further we have compared the immunereactivity of these two constructs in murine model by means of DTH study, LTT, NO assay and ELISA. DTH response was higher in pIR PPE/IFN than pIR PPE group of mice, similar finding also observed in case of LTT and NO production assay . ELISA titer of the pIR PPE/IFN was less than that with PPE only. These preliminary finding can revealed a CMI response of this PPE protein of Map and IFNγhaving synergistic effect on this PPE protein to elicit a T cell based immunity in mice.
The effect of ENSO activity on lower stratospheric water vapor
Authors: Xie F. , Tian W. , Austin J. , Li J. , Tian H. , Shu J. , Chen C.
Published: February 2011

Abstract. Using the ECMWF/NCEP reanalysis data, satellite observations from AURA MLS and UARS HALOE, and Oceanic Niño Index (ONI) data, the effects of El Niño and La Niña events on the stratospheric water vapor changes are investigated. Overall, El Niño events tend to moisten the lower stratosphere but dry the middle stratosphere. La Niña events are likely to dry the lower stratosphere over a narrow band of tropics (5° S–5° N) but have a moistening effect on the whole stratosphere when averaged over a broader region of tropics between 25° S–25° N. The moistening effect of La Niña events mainly occurs in lower stratosphere in the Southern Hemisphere tropics where a significant 20% increase in the tropical upwelling is caused by La Niña events. El Niño events have a more significant effect on the tropical upwelling in the Northern Hemisphere extratropics than in Southern Hemisphere extratropics. The net effect of ENSO activities on the lower stratospheric water vapor is stronger in the Southern Hemisphere tropics than in the Northern Hemisphere tropics.
Trace gas fluxes of CO2, CH4 and N2O in a permanent grassland soil exposed to elevated CO2 in the Giessen FACE study
Authors: Abbasi M. K. , Müller C.
Published: February 2011

Abstract. Long-term field observations showed that N2O fluxes were not significantly affected by elevated CO2 shortly after N application in the Giessen Free Air Carbon dioxide Enrichment (FACE) study. To further investigate this unexpected result a 15N tracer study was carried out under controlled conditions where in parallel treatments either the NH4+ pool (15NH4NO3) or the NO3− pool (NH415NO3) was enriched with 15N. Fluxes of CO2, CH4, and N2O as well as the 15N enrichment of the N2O were measured. Denitrifying Enzyme Activity (DEA), total denitrification (N2 + N2O) and N2−to−N2O ratios were quantified in separate experiments. Over the 57 day incubation, N2O fluxes averaged 0.090 ng N2O–N g−1 h−1 under ambient and 0.083 ng N2O–N g−1 h−1 under elevated CO2 (not significantly different). Based on the 15N enrichments of the N2O the N2O production processes were identified by a two-source model. Results showed that N2O must have also been produced by a third source – possibly related to organic N transformation – which was stimulated by elevated CO2. Soil CO2 fluxes were approximately 20% higher under elevated CO2 than soil from ambient but the differences were not significant. CH4 oxidation rates were on average −1.75 ng CH4−C g−1 h−1 in the elevated and −1.17 ng CH4−C g−1 h−1 in the ambient indicating that elevated CO2 increased the CH4 oxidation by 49% compared to ambient CO2. N fertilization increased CH4 oxidation by 3-fold in both CO2 treatments CO2 did not have any significant effect on DEA while total denitrification and N2–to–N2O ratios increased by 36 and 33%, respectively. The results indicate that shortly after N application elevated CO2 must have stimulated both the N2O production and reduction to N2 to explain the increased N2–to–N2O ratio and at the same time explain the non-responsiveness of the N2O emissions. Thus, the observed variation of the CO2 effect on N2O emissions throughout the year is possibly related to the dynamics of the N2O reductase activity.
Global multi-year O3-CO correlation patterns from models and TES satellite observations
Authors: Voulgarakis A. , Telford P. J. , Aghedo A. M. , Braesicke P. , Faluvegi G. , Abraham N. L. , Bowman K. W. , Pyle J. A. , Shindell D. T.
Published: February 2011

Abstract. The correlation between measured tropospheric ozone (O3) and carbon monoxide (CO) has been used extensively in tropospheric chemistry studies to explore the photochemical characteristics of different regions and to evaluate the ability of models to capture these characteristics. Here, we present the first study that uses multi-year, global, vertically resolved, simultaneous and collocated O3 and CO satellite (Tropospheric Emission Spectrometer) measurements, to determine this correlation in the middle/lower free troposphere for two different seasons, and to evaluate two chemistry-climate models. We find results that are fairly robust across different years, altitudes and timescales considered, which indicates that the correlation maps presented here could be used as benchmarks in future studies. The highest positive correlations (around 0.8) are found in the Northern Pacific during summer, which is a common feature in the observations and the G-PUCCINI model. We make quantitative comparisons between the models using a single-figure metric (C), which we define as the correlation coefficient between the modeled and the observed O3-CO correlations for different regions of the globe. On a global scale, the G-PUCCINI model shows a good performance in the summer (C=0.71) and a satisfactory performance in the winter (C=0.52). It captures midlatitude features very well, especially in the summer, whereas the performance in regions like South America or Central Africa is weaker. The UKCA model (C=0.46/0.15 for July–August/December–January on a global scale) performs better in certain regions, such as the tropics in winter, and it captures some of the broad characteristics of summer extratropical correlations, but it systematically underestimates the O3-CO correlations over much of the globe. It is noteworthy that the correlations look very different in the two models, even though the ozone distributions are similar. This demonstrates that this technique provides a powerful global constraint for understanding modeled tropospheric chemical processes. We investigated the sources of the correlations by performing a series of sensitivity experiments. In these, the sign of the correlation is, in most cases, insensitive to removing different individual emissions, but its magnitude changes downwind of emission regions when applying such perturbations. Interestingly, we find that the O3-CO correlation does not solely reflect the strength of O3 photochemical production, as often assumed by earlier studies, but is more complicated and reflects a mixture of different processes such as transport.
Detailed heterogeneous oxidation of soot surfaces in a particle-resolved aerosol model
Authors: Kaiser J. C. , Riemer N. , Knopf D. A.
Published: February 2011

Abstract. We simulate the heterogeneous oxidation of condensed phase polycyclic aromatic hydrocarbons (PAHs) on soot particles in an urban atmosphere using the particle-resolved aerosol model PartMC-MOSAIC. We focus on the interaction of the major atmospheric oxidants (O3, NO2, OH, and NO3) with PAHs and include competitive co-adsorption of water vapour for a range of atmospheric conditions. For the first time detailed heterogeneous chemistry based on the Pöschl-Rudich-Ammann (PRA) framework is modelled on soot particles with a realistic size distribution and a continuous range of chemical ages. We find PAH half-lives τ1/2 on the order of seconds during the night, when the PAHs are rapidly oxidized by the gas-surface reaction with NO3. During the day, τ1/2 is on the order of minutes and determined mostly by the surface layer reaction of PAHs with adsorbed O3. Such short PAH half-lives may lead to efficient conversion of hydrophobic soot into more hygroscopic particles, thus increasing the particles' aerosol-cloud interaction potential. Despite its high reactivity appears to have a negligible effect on PAH degradation which can be explained by its very low concentration in the atmosphere. An increase of relative humidity from 30% to 80% increases PAH half-lives by up to 50% for daytime degradation and by up to 100% or more for nighttime degradation. Uptake coefficients, averaged over the particle population, are found to be relatively constant over time for O3 (~2×10−7 to ~2×10−6) and NO2 (~5×10−6 to ~10−5) at the different levels of NOx emissions and RH considered in this study. In contrast, those for OH and NO3 depend strongly on the surface concentration of PAhs. We do not find a significant influence of heterogeneous reactions on soot particles on the gas phase composition. The PAH half-lives presented in this paper can be used as parameterisations for the treatment of heterogeneous chemistry in large-scale atmospheric chemistry models.
An aircraft-borne chemical ionization – ion trap mass spectrometer (CI-ITMS) for fast PAN and PPN measurements
Authors: Roiger A. , Aufmhoff H. , Stock P. , Arnold F. , Schlager H.
Published: February 2011

Abstract. An airborne chemical ionization ion trap mass spectrometer instrument (CI-ITMS) has been developed for tropospheric and stratospheric fast in-situ measurements of PAN (peroxyacetyl nitrate) and PPN (peroxypropionyl nitrate). The first scientific deployment of the FASTPEX instrument (FASTPEX = Fast Measurement of Peroxyacyl nitrates) took place in the Arctic during 18 missions aboard the DLR research aircraft Falcon, within the framework of the POLARCAT-GRACE campaign in the summer of 2008. The FASTPEX instrument is described and characteristic properties of the employed ion trap mass spectrometer are discussed. Atmospheric data obtained at altitudes of up to ~12 km are presented, from the boundary layer to the lowermost stratosphere. Data were sampled with a time resolution of 2 s and a 2σ detection limit of 25 pmol mol−1. An isotopically labelled standard was used for a permanent on-line calibration. For this reason the accuracy of the PAN measurements is better than ±10% for mixing ratios greater than 200 pmol mol−1. PAN mixing ratios in the summer Arctic troposphere were in the order of a few hundred pmol mol−1 and generally correlated well with CO. In the Arctic boundary layer and lowermost stratosphere smaller PAN mixing ratios were observed due to a combination of missing local sources of PAN precursor gases and efficient removal processes (thermolysis/photolysis). PPN, the second most abundant PAN homologue, was measured simultaneously. Observed PPN/PAN ratios range between ~0.03 and 0.3.
Interannual variability of air-sea CO2 fluxes and carbonate system parameters in the East Siberian Sea
Authors: Pipko I. I. , Semiletov I. P. , Pugach S. P. , Wåhlström I. , Anderson L. G.
Published: February 2011

Abstract. Over the past couple of decades it has become apparent that air-land-sea interactions in the Arctic have a substantial impact on the composition of the overlying atmosphere (ACIA, 2004). The Arctic Ocean is small (only ~4% of the total World Ocean), but it is surrounded by offshore and onshore permafrost which thaws at increasing rates under warming conditions releasing carbon dioxide (CO2) into the water and atmosphere. This work summarizes data collected from three expeditions in the coastal-shelf zone of the East Siberian Sea (ESS) in September 2003, 2004 and late August–September 2008. It is proposed that the western part of the ESS represents a river- and coastal erosion-dominated ocean margin that is a source for atmospheric CO2. It receives substantial river discharge that also adds organic matter, both dissolved and particulate. This in combination with significant input of organic matter from coastal erosion makes this region being of dominantly heterotrophic character. The eastern part of the ESS is a Pacific water-dominated autotrophic area. It's a high-productive zone, which acts as a sink for atmospheric CO2. The year to year dynamics of partial pressure of CO2 in the surface water as well as the sea-air flux of CO2 varied substantially. In some years the ESS shelf can be mainly heterotrophic and serve as strong source of CO2 (year 2004). Another year significant part of the ESS, where gross primary production exceeds community respiration, acts as a sink for the atmospheric CO2 and the net CO2 flux into the atmosphere is weak (year 2008). High variability of carbon system parameters observed in the ESS shelf is determined by many factors such as riverine runoff, advection of waters from adjacent seas, coastal erosion, primary production/respiration etc. The dynamics of the CO2 sea-air exchange is determined by ocean processes but also by atmospheric circulation which hence has a significant impact on the CO2 sea-air exchange. In this contribution the sea-air CO2 fluxes were evaluated in the ESS based on measured carbonate system (CS) parameters data and annual sea-to-air CO2 fluxes were estimated. It was shown that the total ESS shelf is a net source of CO2 for the atmosphere at a range from 0.5×1012 to 3.3×1012 g C.
Microbial food web dynamics along a soil chronosequence of a glacier forefield
Authors: Esperschütz J. , Pérez-de-Mora A. , Schreiner K. , Welzl G. , Buegger F. , Zeyer J. , Hagedorn F. , Munch J. C. , Schloter M.
Published: February 2011

Abstract. Microbial food webs are critical for efficient nutrient turnover providing the basis for functional and stable ecosystems. However, the successional development of such microbial food webs and their role in "young" ecosystems is unclear. Due to a continuous glacier retreat since the middle of the 19th century, glacier forefields have expanded offering an excellent opportunity to study food web development at differently developed soils. In the present study, litter degradation and the corresponding C fluxes into microbial communities were investigated along the forefield of the Damma glacier (Switzerland). 13C-enriched litter of the pioneering plant Leucanthemopsis alpina (L.) Heywood was incorporated into the soil at sites that have been free from ice for approximately 10, 60, 100 and more than 700 years. The structure and function of microbial communities were identified by 13C analysis of phospholipid fatty acids (PLFA) and phospholipid ether lipids (PLEL). Results showed increasing microbial diversity and biomass, and enhanced proliferation of bacterial groups as ecosystem development progressed. Initially, litter decomposition proceeded faster at the more developed sites, but at the end of the experiment loss of litter mass was similar at all sites, once the more easily-degradable litter fraction was processed. As a result incorporation of 13C into microbial biomass was more evident during the first weeks of litter decomposition. 13C enrichments of both PLEL and PUFA biomarkers following litter incorporation were observed at all sites, suggesting similar microbial foodwebs at all stages of soil development. Nonetheless, the contribution of bacteria and actinomycetes to litter turnover became more pronounced as soil age increased in detriment of archaea, fungi and protozoa, more prominent in recently deglaciated terrain.
Biogeochemistry of sediments from restricted exchange environments of Kandalaksha Bay, White Sea, Russian Arctic
Authors: Koukina S. , Vetrov A. , Belyaev N.
Published: February 2011

Abstract. The White Sea of Russian Arctic is characterized by extreme diversity of enclosed estuarine systems that are often sites of unique biota. The present study focuses on surface sediments from representative restricted exchange environments of the inner part of Kandalaksha Bay, adjacent to the Karelian shore of the White Sea. The TOC and n-alkanes distribution study revealed the major input of terrestrial organic matter into the sediments from higher plants and minor presence of autochthonous microbial sources. Metal (Fe, Mn, Cu, Zn, Cr and Pb) forms study showed that metals in sediments occur mainly in a biogeochemically stable mineral-incorporated form, which comprises up to 98% of total metal content, while labile (acid soluble) and organically bound (alkali soluble) forms make up to 3–11% and 2–12% of total metal content, respectively. Presumably, the major part of both acid soluble and alkali soluble forms is comprised of metals associated with easily soluble amorphous Fe-oxides and bound to sediment organic matter. According to sediment quality guidelines, all trace-metal contents were below the threshold levels. Among sites studied, the heightened contents of bioavailable metal forms are related to sediments enriched in organic matter and/or located within the sea-fresh water barrier zones. The elements studied may be arranged in the following decreasing sequence according to their potential bioavailability: Cu > Zn > Mn > Fe > Cr > Pb. The present study can serve as a basis for comprehensive environmental assessment of the region and objective anoxia prognosis in Arctic ecosystems, while the role of microbial community in element speciation in sediments needs special attention.
Carbon balance of surfaces vs. ecosystems: advantages of measuring eddy covariance and soil respiration simultaneously in dry grassland ecosystems
Authors: Nagy Z. , Pintér K. , Pavelka M. , Darenová E. , Balogh J.
Published: February 2011

Abstract. An automated open system for measurement of soil CO2 efflux (Rsc) was developed and calibrated against known fluxes and tested in the field, while measuring soil respiration also by the gradient method (Rsg) at a dry sandy grassland (Bugac, Hungary). Ecosystem respiration (Reco) was measured by the eddy covariance technique. Small chamber size (5 cm in diameter) of the chamber system made it possible to use the chambers also in vegetation gaps, thereby avoiding the necessity of removing shoots, the disturbance of the spatial structure of vegetation and the upper soil layer. Low air flow rates associated with small chamber volume and chamber design allowed the overpressure range to stabilize between 0.05–0.12 Pa. While the correlation between ecosystem and soil CO2 efflux rates as measured by the independent methods was significant, Reco rates were similar or even lower than Rsc in the low flux (up to 2 μmol CO2 m−2 s−1) range, probably due to the larger than assumed storage flux. The gradient method showed both up and downward CO2 fluxes originating from the main rooting zone after rains. Downward fluxes within the soil profile amounted to 15% of the simultaneous upward fluxes and to ~ 7.6% of the total (upward) effluxes during the 3 months study. The upper 5 cm soil layer contributed to ~ 50% of the total soil CO2 efflux. The continuously operated automatic open chamber system and the gradient system makes possible the detection of situations when the eddy system underestimates Reco, gives the lower limit of underestimation (chamber system) and helps in quantifying the downward flux component of soil respiration (gradient method) between the soil layers. These latter (downward) fluxes are expected to seriously affect (1) the Reco vs. temperature response functions and (2) the net ecosystem exchange of CO2 (NEE) vs. photon flux density response functions, therefore potentially affecting also the gap filling procedures and to led to a situation (3) when the measured surface and the real time ecosystem fluxes will necessarily differ in the short term. Simultaneous measurements of Reco and soil CO2 effluxes may reveal the time and degree of the above decoupling, thereby contributing to decrease uncertainty, associated with eddy flux measurements over flat terrains. While the correlation between chamber fluxes and gradient fluxes was strong, gradient fluxes were generally larger than the flux from chambers. Calibration of gradient flux system by chamber effluxes is proposed.
Climate change and mountain water resources: overview and recommendations for research, management and policy
Authors: Viviroli D. , Archer D. R. , Buytaert W. , Fowler H. J. , Greenwood G. B. , Hamlet A. F. , Huang Y. , Koboltschnig G. , Litaor M. I. , López-Moreno J. I. , Lorentz S. , Schädler B. , Schreier H. , Schwaiger K. , Vuille M. , Woods R.
Published: February 2011

Abstract. Mountains are essential sources of freshwater for our world, but their role in global water resources could well be significantly altered by climate change. How well do we understand these potential changes today, and what are implications for water resources management, climate change adaptation, and evolving water policy? To answer above questions, we have examined 11 case study regions with the goal of providing a global overview, identifying research gaps and formulating recommendations for research, management and policy. After setting the scene regarding water stress, water management capacity and scientific capacity in our case study regions, we examine the state of knowledge in water resources from a highland-lowland viewpoint, focusing on mountain areas on the one hand and the adjacent lowland areas on the other hand. Based on this review, research priorities are identified, including precipitation, snow water equivalent, soil parameters, evapotranspiration and sublimation, groundwater as well as enhanced warming and feedback mechanisms. In addition, the importance of environmental monitoring at high altitudes is highlighted. We then make recommendations how advancements in the management of mountain water resources under climate change could be achieved in the fields of research, water resources management and policy as well as through better interaction between these fields. We conclude that effective management of mountain water resources urgently requires more detailed regional studies and more reliable scenario projections, and that research on mountain water resources must become more integrative by linking relevant disciplines. In addition, the knowledge exchange between managers and researchers must be improved and oriented towards long-term continuous interaction.
Stream recession curves and storage variability in small watersheds
Authors: Krakauer N. Y. , Temimi M.
Published: February 2011

Abstract. The pattern of streamflow recession after rain events offers clues about the relationship between watershed runoff (observable as river discharge) and water storage (not directly observable) and can help in water resource assessment and prediction. However, it has not been systematically analyzed across flow rates or related to independent assessments of terrestrial water storage. We characterized the streamflow recession pattern in 61 relatively undisturbed small watersheds (1–100 km2) across the coterminous United States with multiyear records of hourly streamflow from automated gauges. We used the North American Regional Reanalysis (NARR) to help identify periods where precipitation, snowmelt, and evaporation were small compared to streamflow. The order of magnitude of the recession timescale increases from 1 day at high flow rates (~1 mm/h) to 10 days at low flow rates (~0.01 mm/h), leveling off at low flow rates. There is significant variability in the recession timescale at a given flow rate between basins, correlated with climate and geomorphic variables such as the ratio of mean streamflow to precipitation and soil water infiltration capacity. Stepwise multiple regression was used to construct a six-variable predictive model that explained some 80% of the variance in recession timescale at high flow rates and 30–50% at low flow rates. Seasonal and interannual variability in storage shows similar time evolution to but is up to a factor of 10 smaller than regional-scale water storage variability estimated from GRACE satellite gravity data and from land surface modeling forced by observed meteorology. The discrepancy may point to a "disconnection" between the conceptual pool that supplies streamflow during dry periods and other dynamic pools such as soil moisture and deep groundwater.
Modeling the temperature evolution of Svalbard permafrost during the 20th and 21st century
Authors: Etzelmüller B. , Schuler T. V. , Isaksen K. , Christiansen H. H. , Farbrot H. , Benestad R.
Published: February 2011

Abstract. Variations in ground thermal conditions in Svalbard were studied based on measurements and modelling. Ground temperature data from boreholes were used to calibrate a transient heat flow model describing depth and time variations in temperatures. The model was subsequently forced with historical surface air temperature records and possible future temperatures downscaled from multiple global climate models. We discuss ground temperature development since the early 20th century, and the thermal responses in relation to ground characteristics and snow cover. The modelled ground temperatures show a gradual increase between 1912 and 2010, by about 1.5 °C to 2 °C at 20 m depth. The active layer thickness (ALT) is modelled to have increased slightly, with the rate of increase depending on water content of the near-surface layers. The used scenario runs predict a significant increase in ground temperatures and an increase of ALT depending on soil characteristics.
Oxidation of Vulcanized Rubber. Effect of Temperature, State of Cure, and Thickness
Authors: Kemp A. R. , Ingmanson J. H. , Mueller G. S.
Published: February 2011

1. A previous investigation of the rate of oxidation of rubber over the temperature range of 60° to 80° C. has been extended to 90°, 100° and 110° C. 2. The rate of oxidation over the range which accounts for substantial deterioration of tensile strength appears to be a straight-line function of the time of aging from 60° up to an including 90° C. The rate of oxidation at 100° C. appears to diverge somewhat from a straight-line function of time decreasing as oxidation proceeds. 3. The rate of oxidation increases with increased temperature. Over the range of 60° to 110° C, the rate is doubled for each 7.5° increase in temperature, corresponding to a temperature coefficient of oxidation of 2.5. 4. Tensile strength decreases as a straight-line function of the time of aging and of the quantity of oxygen absorbed. 5. The quantity of absorbed oxygen, determined by weight gain corresponding to a 50 per cent decrease in tensile strength, varies with the temperature of oxidation. At 60° C. the oxygen requirement for 50 per cent deterioration is about 1.30 per cent, and at 110° C. about 0.65 per cent on the rubber hydrocarbon content. 6. Tensile strength increases, probably due to a mild curing effect, when specimens of the compound are heated in an atmosphere where the oxygen is replaced with carbon dioxide for the same periods of time at 80° and 110° C, were required to cause a 50 per cent deterioration in tensile strength in an oxygen atmosphere. 7. With increased time of vulcanization, the rate of oxidation increases. Oxidation appears to be autocatalytic in the case of overvulcanized rubber. 8. As time of vulcanization increases, there is a decrease in the quantity of oxygen required to cause a given decrease in tensile strength. 9. Thickness variations of 0.43 to 1.90 mm. in test-specimens of a compound containing an antioxidant do not affect quantity of oxygen absorbed or degree of tensile strength deterioration when aging is conducted at 80° C. and 3.5 kg. per sq. cm. oxygen pressure. 10. When tetramethylthiuram disulfide is used for vulcanization in place of sulfur, there appears to be no change in the mechanism of oxidation, but the rate of oxidation is reduced.
Experiments on the Determination of the Activity of Carbon Black by Its Power of Adsorbing Carbon Tetrachloride Vapor
Authors: Patryn T.
Published: February 2011

On the basis that a material like carbon black must, because of its very high ratio of surface area to volume, possess very high adsorptive capacity, several investigators have attempted to establish the relationship between the adsorptive capacity of carbon black and its activity in rubber. Spear and Moore used aqueous solutions of malachite green, Victoria blue and hexamethylenetetramine; Beaver and Keller used iodine in aqueous potassium iodide; Goodwin and Park used iodine in carbon tetrachloride and also an aqueous solution of methylene blue; Carson and Sebrell used iodine, benzoic acid, mercaptobenzothiazole and diphenylguanidine. All these workers tested various types of carbon black. If one examines critically the data of these several investigators from the point of view of the relation between the adsorptive capacity of a carbon black and its activity in rubber, it will be evident that the investigations do not lead to any reliable method whereby the behavior of carbon black in rubber can be judged by its adsorptive capacity.
Dilatometer Studies of Pigment-Rubber Systems
Authors: Jones H. C. , Yiengst H. A.
Published: February 2011

A number of years ago Schippel observed that, when certain pigmented rubber stocks were stretched, there was a reduction in specific gravity of the compound. This he attributed to the separation of the rubber from the pigment, resulting in vacuole formation. Green confirmed Schippel's explanation with the aid of a microscope. He prepared photomicrographs of stretched rubber films showing the formation of vacuoles at coarse pigment particles and undispersed pigment acting as single large particles. These vacuoles were conical in shape, and extended from one or both sides of the particles in the direction of elongation. Depew and Easley reported microscopic results relating particle surface and particle size and shape to the formation of vacuoles in stretched rubber. Several years ago Holt and McPherson designed a dilatometer to measure the volume change of rubber compounds under tension. In stretching gum-rubber bands, they noted a decrease in volume, which they ascribed to the fibering of the rubber, and an increase in volume of pigmented rubber bands, which they explained by the formation of vacuoles around the pigment particles. Furthermore these investigators pointed out that the decrease in volume of rubber on stretching is influenced by the same considerations as the x-ray diffraction, since it is observed only above a certain critical elongation and is greater the higher the elongation, the lower the temperature, and the longer the time the sample is kept stretched. Holt and McPherson dealt almost entirely with gum stocks except that they included measurements on a whiting and a carbon black stock. The object of this investigation was to extend the work of Holt and McPherson to a more complete study of pigmented stocks, with particular reference to those compounded with zinc oxide.
Investigation of the Fine Structure of High-Molecular Substances with the Universal Electron Microscope. Part II. The Morphology of Rubber and Buna
Authors: Von Ardenne M. , Beischer D.
Published: February 2011

In the last twenty years scientific methods and research have contributed to an ever increasing extent to the improvement of technical processes and to better control of these processes. In the production of crude rubber, for example, the personal skill of experienced experts, which formerly was the only controlling factor, has now been supplemented by a knowledge of how to carry out the process with rigid physico-chemical control. In addition to this, the development of rubber-like materials, such as Buna, has brought to the field of highly elastic materials new accomplishments and methods of investigation of fundamental importance. Since the structural units of rubber and of rubber-like materials lie within the range of colloidal dimensions, the various methods of colloid research have been the chief means of investigation of these materials in the past. Recently the electron microscope has become a new aid to colloid research, and has made possible the direct determination and measurement of the form and size of structural units and their mutual spatial arrangement. In view of this, it was but natural to undertake an electron microscopic investigation of the morphology of rubber and Buna. Even the first broad approach to this problem, which is described in the present communication, makes it evident that the electron microscope technique offers an easy means of gaining an insight into the structure of these systems in various fields of rubber technology.
Transparent Rubber Compounds. The Effect of Chemical Composition of Magnesium Carbonate Fillers
Authors: Bixby Willard F. , Cramer Howard I.
Published: February 2011

From this investigation the following conclusions may be drawn. 1. The x-ray results of Bixby and Hauser have been substantiated by chemical analysis and by microscopic examination. The magnesium carbonate productive of highest light transmitting properties is of the type: 5MgO.4CO2.xH2O. The normal carbonate, MgCO3, gives very low transmissions. 2. The best Japanese carbonate studied (sample No. 3) is pure 5MgO.4CO2.xH2O. 3. A domestic carbonate (sample No. 20), which is also pure 5MgO.4CO2.xH2O, is commercially available and produces transparency in rubber compounds equal to that obtained with the Japanese product. 4. Domestic carbonates in general contain more carbon dioxide than is required by a 5MgO.4CO2.xH2O carbonate, and are probably mixtures of this material and of the normal carbonate, MgCO3. 5. Light transmitting properties fall rapidly as the proportion of normal carbonate, MgCO3, rises. 6. Carbonates containing less than enough carbon dioxide to provide a 5MgO.4CO2.xH2O carbonate are probably mixtures of this material and hydrated magnesium oxide, MgO.H2O. 7. In preparing basic carbonates for use in producing high light-transmitting rubber, it is better to produce a material with slightly less carbon dioxide than necessary for a 5MgO.4CO2.xH2O carbonate, rather than more. 8. Particle size is an important factor influencing light transmission, especially when the normal carbonate, MgCO3, is present. Generally speaking, especially in the size ranges encountered in these carbonates, a finely divided MgCO3 will offer greater hindrance to the passage of light than will a larger size material.
Factors Influencing the T-50 Value
Authors: Gardner E. R.
Published: February 2011

The paramount importance of producing the correct state of cure in a rubber article is too well known to need further emphasis. In the light of this, statement, the necessity of possessing a convenient and accurate method of assessing the state of cure is obvious. Before the advent of the T-50 test, the state of cure was measured mainly by a determination of the quantity of sulfur combined with the rubber, of stress-strain properties, or of optimum resistance to aging. The determination of combined sulfur has a disadvantage which is immediately apparent; it is laborious. Also, the figure obtained includes the amount of sulfur combined with metallic oxides used as activators, and to get an accurate measure of the quantity of sulfur combined with the rubber, a second analysis must be undertaken. There is yet another disadvantage, namely, that sulfur-containing substances added to the rubber mix interfere with the determination. The determination of tensile strength, modulus, or resistance to aging cannot be regarded as suitable for giving an accurate measure of cure, and are probably best looked on as complementary to the sulfur determination. With this state of affairs existing, it was only to be expected that, on the introduction of an entirely new and independent method of testing the state of cure, far-reaching claims should have been made, and also that the discovery should have been hailed as the elixir for all cure-testing ills. The present work was undertaken with a view to testing the validity of the claims put forward and to investigating, prior to the introduction of the T-50 as a routine test, the effect of variables likely to be encountered.
Infra-Red Spectra of Rubber and High Polymers
Authors: Sears W. C.
Published: February 2011

The rubber industry is interested in all methods for studying the structure of highly polymerized substances. Infra-red spectroscopy has been recognized by recent workers as a possible means for determining the valence forces in long chain molecules. Accordingly, the infra-red spectra of rubber and related compounds have been measured by several workers. An investigation of rubber, gutta percha, indene, polyindene, styrene, polystyrene, polyvinylacetate and polyvinylchloracetate has been carried out by Stair and Coblentz. Later Williams measured natural and vulcanized rubber, rubber hydrochloride, isoprene, styrene and polymerized butadiene in the region between 2.5µ and 9µ, but his spectra of rubber did not agree with that of Stair and Coblentz. Williams and Taschek reported that the bands in rubber become broader with increasing stretch. Recently a rough survey of the infra-red transmission of rubber, Pliofilm, Vinylite XYSG, Shawinigan V-15, polystyrene, methyl methacrylate polymer and Cellophane has been made by Wells. The Raman data of rubber obtained by Gehman and Osterhof are in fair agreement with the infra-red results of Stair and Coblentz.
Elastic and Thermoelastic Properties of Rubberlike Materials. A Statistical Theory
Authors: Guth Eugene , James Hubert M.
Published: February 2011

A statistical theory of the elasticity of rubber and similar high-molecular compounds was proposed by one of the authors several years ago, and an extended form of the theory was presented recently. The theory is applied here to vulcanizates, and shows the dependence of stress on both temperature and deformation for both extension and compression. The foundations of the theory will be stated precisely, inasmuch as some recent articles dealing with it are likely to lead to misunderstandings concerning the assumption of free rotation and structure of long-chain compounds, such as vulcanized rubber. The possible ro^le of kinetic effects for the rubber type of elasticity has been discussed qualitatively by Wöhlisch, Busse, Karrer, Meyer, Susich and Valkó, and Shacklock. The first quantitative theory was developed by one of the authors in 1934 and published later, partly in collaboration with Mark. In the statistical theory, the main assumption is that of quasi-free rotation in a rubber molecule around a single carbon-carbon bond. An important consequence of this free rotation is that the molecules are coiled in the unstretched state. The contraction of stretched rubber is due mainly to the tendency of the stretched chain to change from a less probable stretched form back to the most probable coiled form. This happens in accordance with the statistical interpretation of the second law of thermodynamics, and is not caused by forces. Our theory, then, is that the kinetic motion of freely rotating groups in the rubber molecule is the main cause of contraction.
Report of the Crude Rubber Committee. Presented at the Semi-Annual Meeting of the Division of Rubber Chemistry—April 11, 1941 Concluding Remarks
Authors: Sackett G. A. , McColm E. M. , Nellen A. H. , Oldham E. W. , Parrish W. D. , Schatzel R. A. , Walton J. C.
Published: February 2011

The Crude Rubber Committee has not given up the possibility of working out a test for determining the age-resistance properties of crude rubber. Much laboratory work remains to be done on this problem before reaching any decision, and such an investigation will be considerably delayed by the present need for work for national defense. The Committee is giving serious consideration to the problem of sampling crude rubber. The drawing of a representative sample presents more of a practical statistical problem than one of rubber technology, and the adoption of a standard method must be based on a statistical study. It is hoped that a paper on this subject can be presented before the Division of Rubber Chemistry at an early date.