bluuebunny/crossref_metadata_2025 huggingface dataset:
Biological Therapy for Psoriatic Arthritis in Clinical Practice: Outcomes Up to 2 Years
Authors: VIRKKI LIISA M. , SUMATHIKUTTY BINDU C. , AARNIO MERJA , VALLEALA HEIKKI , HEIKKILÄ RIITTA , KAUPPI MARKKU , KARSTILA KRISTA , PIRILÄ LAURA , EKMAN PÄIVI , SALOMAA SIRPA , ROMU MATTI , SEPPÄLÄ JOUKO , NIINISALO HELENA , KONTTINEN YRJÖ T. , NORDSTRÖM DAN C.
Published: August 2010

Objective.

To evaluate the performance of biological drugs in psoriatic arthritis (PsA) in a routine care setting, using the Finnish national register of biological treatment (ROB-FIN).

Methods.

Patients with PsA who started therapy with infliximab or etanercept between June 2000 and February 2006 (n = 127) were followed for up to 24 months. Response was evaluated using American College of Rheumatology response criteria including individual measures.

Results.

Significantly diminished values for swollen and tender joints, patient’s global and pain assessments, doctor’s global assessment of disease activity, erythrocyte sedimentation rate, C-reactive protein, and Health Assessment Questionnaire score were observed within 3 months after commencement of both infliximab and etanercept. Values remained significantly lower throughout the 24 months of followup. ACR20 response at 3 months was 79% (n = 22/28) for infliximab and 76% (n = 34/45) for etanercept. The first biological drug was discontinued in 16% due to lack of effectiveness and in 6% due to adverse events.

Conclusion.

Anti-tumor necrosis factor-α therapy, often combined with conventional disease-modifying antirheumatic drugs, appeared to have limited toxicity and persistent effectiveness for up to 2 years in a cohort of Finnish patients with severe peripheral PsA.
Cost of Illness from the Public Payers’ Perspective in Patients with Ankylosing Spondylitis in Rheumatological Care
Authors: STRÖMBECK BRITTA , ENGLUND MARTIN , BREMANDER ANN , JACOBSSON LENNART T.H. , KEDZA LJUBA , KOBELT GISELA , PETERSSON INGEMAR F.
Published: August 2010

Objective.

To estimate the incremental costs to public payers for patients with ankylosing spondylitis (AS) of working age compared with reference subjects from the general population.

Methods.

We investigated total costs for 3 years (2005–2007) in 116 outpatients under 66 years of age with AS attending rheumatological care in Malmö, Sweden. Mean (SD) age was 46 (11) years and mean (SD) disease duration was 24 (11) years. Two subjects per AS patient matched for age, sex, and residential area were selected from the Population Register to serve as a reference group. We retrieved data concerning sick leave, prescription drugs, and healthcare consumption from Swedish health-cost registers by the unique personal identification numbers.

Results.

The mean total cost for the 3-year period 2005–2007 was US $37,095 (SD $30,091) for patients with AS, and $11,071 (SD $22,340) for the reference group. The mean indirect cost was $19,618 and $5905, respectively. Mean cost for healthcare was $8998 for the AS patients and $4187 for the reference subjects, and mean cost for drugs was $8479 and $979, respectively. The patients with AS treated with biological therapy constituted 80% of the total drug cost, but just 40% of the cost for disability pension.

Conclusion.

Patients with AS had 3-fold increase in costs compared to reference subjects from the general population, and the drug costs were almost 10 times as high. Production losses (indirect cost) represented more than half of total cost (53%).
La course aux « belles affaires », la congruence d'intérêts professionnels et organisationnels dans la police judiciaire
Authors: Dedieu François
Published: August 2010

L’article porte sur l’étude du travail quotidien d’une sûreté départementale de la région parisienne, unité de police judiciaire appartenant à la Direction Départementale de la Sécurité Publique (DDSP). Au moyen d’une étude organisationnelle, l’article montre que la mobilisation professionnelle au sein des unités de police judiciaire s’explique non pas seulement par la congruence existante entre le mandat institutionnel et les missions de ces unités – la lutte contre le crime – comme le démontre la littérature spécialisée, mais également par une course aux belles affaires qui permet de faire converger les intérêts intrinsèques de la profession policière avec les objectifs de résultats de cette unité. Nous montrons plus particulièrement que deux caractéristiques organisationnelles – un mode d’évaluation basé sur la qualité des affaires et un système de recrutement par cooptation – favorisent cette course aux belles affaires qui donne lieu à un équilibre systémique vertueux pour la performance de cette unité de police judiciaire.
Les juges belges face à l'(in)exécution des peines
Authors: Beyens Kristel , Françoise Clémence , Scheirs Veerle
Published: August 2010

En Belgique, l’inexécution totale ou partielle des peines d’emprisonnement fait depuis quelque temps déjà l’objet de nombreux mécontentements, notamment de la part des magistrats. Sur la base d’une recherche empirique menée auprès des magistrats belges (francophones et néerlandophones), cet article propose un aperçu des divergences de position de la magistrature belge face à l’ (in) exécution supposée de « leurs » peines et face à l’adoption de comportement anticipatif. Nous constatons que les juges adoptent différentes attitudes : certains admettent ouvertement anticiper l’ (in) exécution des peines et prononcent des condamnations plus lourdes afin de s’assurer que le condamné séjourne au moins un certain temps en prison, d’autres contestent ces pratiques et affirment ne pas prendre en compte les possibles remaniements de leur décision. Afin de donner aux remises en liberté une base juridique solide et une plus grande légitimité, les tribunaux de l’application des peines ont été introduits en Belgique en 2007. Cet article entend également présenter la façon dont les juges perçoivent ces nouveaux tribunaux et envisager dans quelle mesure leur introduction influence leurs décisions. Notre analyse montre que les décisions pénales ne sont pas seulement le résultat d’une activité légale formelle, mais sont aussi une pratique sociale, prenant place dans un contexte social, organisationnel et culturel spécifique.
A Short Note on the Higher Level Version of the Krull–Baer Theorem
Authors: Velušček Dejan
Published: August 2010

Klep and Velušček generalized the Krull–Baer theorem for higher level preorderings to the non-commutative setting. A n-real valuation v on a skew field D induces a group homomorphism . A section of is a crucial ingredient of the construction of a complete preordering on the base field D such that its projection on the residue skew field kv equals the given level 1 ordering on kv. In the article we give a proof of the existence of the section of , which was left as an open problem by Klep and Velušček, and thus complete the generalization of the Krull–Baer theorem for preorderings.
Low sensitivity of cloud condensation nuclei to changes in the sea-air flux of dimethyl-sulphide
Authors: Woodhouse M. T. , Carslaw K. S. , Mann G. W. , Vallina S. M. , Vogt M. , Halloran P. R. , Boucher O.
Published: August 2010

Abstract. The emission of dimethyl-sulphide (DMS) gas by phytoplankton and the subsequent formation of aerosol has long been suggested as an important climate regulation mechanism. The key aerosol quantity is the number concentration of cloud condensation nuclei (CCN), but until recently global models did not include the necessary aerosol physics to quantify CCN. Here we use a global aerosol microphysics model to calculate the sensitivity of CCN to changes in DMS emission using multiple present-day and future sea-surface DMS climatologies. Calculated annual fluxes of DMS to the atmosphere for the five model-derived and one observations based present day climatologies are in the range 15.1 to 32.3 Tg a−1 sulphur. The impact of DMS climatology on surface level CCN concentrations was calculated in terms of summer and winter hemispheric mean values of ΔCCN/ΔFluxDMS, which varied between −43 and +166 cm−3/(mg m−2 day−1 sulphur), with a mean of 63 cm−3/(mg m−2 day−1 sulphur). The range is due to CCN production in the atmosphere being strongly dependent on the spatial distribution of the emitted DMS. The relative sensitivity of CCN to DMS (i.e. fractional change in CCN divided by fractional change in DMS flux) depends on the abundance of non-DMS derived aerosol in each hemisphere. The relative sensitivity averaged over the five present day DMS climatologies is estimated to be 0.02 in the northern hemisphere (i.e. a 0.02% change in CCN for a 1% change in DMS) and 0.07 in the southern hemisphere where aerosol abundance is lower. In a globally warmed scenario in which the DMS flux increases by ~1% relative to present day we estimate a ~0.1% increase in global mean CCN at the surface. The largest CCN response occurs in the Southern Ocean, contributing to a Southern Hemisphere mean annual increase of less than 0.2%. We show that the changes in DMS flux and CCN concentration between the present day and global warming scenario are similar to interannual differences due to variability in windspeed. In summary, although DMS makes a significant contribution to global marine CCN concentrations, the sensitivity of CCN to potential future changes in DMS flux is very low. This finding, together with the predicted small changes in future seawater DMS concentrations, suggests that the role of DMS in climate regulation is very weak.
Technical Note: Propagating correlations in atmospheric inversions using different Kalman update smoothers
Authors: Tang J. , Zhuang Q.
Published: August 2010

Abstract. Propagating correlations between on-line and off-line state variables in the problem of sequential inversion of surface fluxes for atmospheric CH
Modelling multi-phase halogen chemistry in the coastal marine boundary layer: investigation of the relative importance of local chemistry vs. long-range transport
Authors: Lowe D. , Ryder J. , Leigh R. , Dorsey J. R. , McFiggans G.
Published: August 2010

Abstract. Measurements of significant concentrations of IO, I2 and BrO in a semi-polluted coast environment at Roscoff, in North-West France, have been made as part of the Reactive Halogens in the Marine Boundary Layer (RHaMBLe) campaign undertaken in September 2006. We use a one-dimensional column model, with idealised I2 emissions predicted using macroalgael maps and tidal data from the littoral area surrounding Roscoff, to investigate the probable causes for these observations. The coupled microphysical and chemical aerosol model simulates mixed-phase halogen chemistry using two separate particle modes, seasalt and non-seasalt, each comprising of eight size-sections. This work confirms the finding of a previous study that the BrO measurements are most likely caused by unknown, local sources. We find that the remote observations of IO and I2 are best replicated using the I2 recycling mechanism suggested by previous studies, but that such a mechanism is not wholly necessary. However we suggest that focussed observations of the changes in NOx and NOy concentrations, as well as changes in the nitrate fraction of the non-seasalt aerosol mode, in the presence of I2 bursts could be used to determine the atmospheric relevance of the predicted I2 recycling mechanism.
A high-resolution mass spectrometer to measure atmospheric ion composition
Authors: Junninen H. , Ehn M. , Petäjä T. , Luosujärvi L. , Kotiaho T. , Kostiainen R. , Rohner U. , Gonin M. , Fuhrer K. , Kulmala M. , Worsnop D. R.
Published: August 2010

Abstract. In this paper we present recent achievements on developing and testing a tool to detect the composition of ambient ions in the mass/charge range up to 2000 Th. The instrument is an Atmospheric Pressure Interface Time-of-Flight Mass Spectrometer (APi-TOF, Tofwerk AG). Its mass accuracy is better than 0.002%, and the mass resolving power is 3000 Th/Th. In the data analysis, a new efficient Matlab based set of programs (tofTools) were developed, tested and used. The APi-TOF was tested both in laboratory conditions and applied to outdoor air sampling in Helsinki at the SMEAR III station. Transmission efficiency calibrations showed a throughput of 0.1–0.5% in the range 100–1300 Th for positive ions, and linearity over 3 orders of magnitude in concentration was determined. In the laboratory tests the APi-TOF detected sulphuric acid-ammonia clusters in high concentration from a nebulised sample illustrating the potential of the instrument in revealing the role of sulphuric acid clusters in atmospheric new particle formation. The APi-TOF features a high enough accuracy, resolution and sensitivity for the determination of the composition of atmospheric small ions although the total concentration of those ions is typically only 400–2000 cm−3. The atmospheric ions were identified based on their exact masses, utilizing Kendrick analysis and correlograms as well as narrowing down the potential candidates based on their proton affinities as well isotopic patterns. In Helsinki during day-time the main negative ambient small ions were inorganic acids and their clusters. The positive ions were more complex, the main compounds were (poly)alkyl pyridines and – amines. The APi-TOF provides a near universal interface for atmospheric pressure sampling, and this key feature will be utilized in future laboratory and field studies.
Formaldehyde measurements by Proton transfer reaction – Mass Spectrometry (PTR-MS): correction for humidity effects
Authors: Vlasenko A. , Macdonald A .M. , Sjostedt S. J. , Abbatt J. P. D.
Published: August 2010

Abstract. Formaldehyde measurements can provide useful information about photochemical activity in ambient air, given that HCHO is formed via numerous oxidation processes. Proton transfer reaction mass spectrometry (PTR-MS) is an online technique that allows measurement of VOCs at the sub-ppbv level with good time resolution. PTR-MS quantification of HCHO is hampered by the humidity dependence of the instrument sensitivity, with higher humidity leading to loss of PTR-MS signal. In this study we present an analytical, first principles approach to correct the PTR-MS HCHO signal according to the concentration of water vapor in sampled air. The results of the correction are validated by comparison of the PTR-MS results to those from a Hantzsch fluorescence monitor which does not have the same humidity dependence. Results are presented for an intercomparison made during a field campaign in rural Ontario at Environment Canada's Centre for Atmospheric Research Experiments.
High time-resolution chemical characterization of the water-soluble fraction of ambient aerosols with PILS-TOC-IC and AMS
Authors: Timonen H. , Aurela M. , Carbone S. , Saarnio K. , Saarikoski S. , Mäkelä T. , Kulmala M. , Kerminen V.-M. , Worsnop D. R. , Hillamo R.
Published: August 2010

Abstract. A particle-into-liquid sampler (PILS) was coupled with a total organic carbon analyzer (TOC) and two ion chromatographs (IC) to enable high time-resolution measurements of water-soluble ions and water-soluble organic carbon (WSOC) by a single sampling and analytical set-up. The new high time-resolution measurement system, the PILS-TOC-IC, was able to provide essential chemical and physical information about fast changes in composition, concentrations and likely sources of the water-soluble fraction of atmospheric aerosol. The concentrations of major water-soluble ions and WSOC were measured by the PILS-TOC-IC system from 25 April to 28 May 2009. The data of the PILS-TOC-IC setup was compared with the data from the High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) data measured from 25 April to 8 May 2009. The measured water-soluble particulate organic matter (WSPOM) concentration varied typically from 0.10 to 8.8 μg m−3 (on average 1.5 μg m−3). The WSPOM contributed on average 51% to particulate organic matter (POM) measured with the AMS. The correlation between the data of all the online measurement devices (AMS, PILS-TOC-IC, semicontinuous EC/OC carbon analyzer and TEOM) was excellent. For sulfate, nitrate and ammonium the correlations between the PILS-TOC-IC and AMS were 0.93, 0.96 and 0.96, respectively. The correlation between WSPOM and POM was also strong (r = 0.88). The identified sources of WSPOM were long-range transported biomass burning and secondary organic aerosol (SOA) formation. WSPOM and oxalate produced in biomass burning were clearly correlated with carbon monoxide.
A geostationary thermal infrared sensor to monitor the lowermost troposphere: O3 and CO retrieval studies
Authors: Claeyman M. , Attié J.-L. , Peuch V.-H. , El Amraoui L. , Lahoz W. A. , Josse B. , Ricaud P. , von Clarmann T. , Höpfner M. , Orphal J. , Flaud J.-M. , Edwards D. P. , Chance K. , Liu X. , Pasternak F. , Cantié R.
Published: August 2010

Abstract. This paper describes the capabilities of a nadir thermal infrared (TIR) sensor proposed for embarkation onboard a geostationary platform to monitor ozone (O3) and carbon monoxide (CO) for air quality (AQ) purposes. To assess the capabilities of this sensor we perform idealized retrieval studies considering typical atmospheric profiles of O3 and CO over Europe with different instrument configurations (signal to noise ratio and spectral sampling interval) using the KOPRA forward model and the KOPRA-fit retrieval scheme based on the Tikhonov-Phillips regularization. We then select a configuration, referred to as GEO-TIR, optimized for providing information in the lowermost troposphere (LmT; 0–3 km in height). For the GEO-TIR configuration we obtain around 1.5 degrees of freedom for O3 and 2 for CO at altitudes between 0 and 15 km. The error budget of GEO-TIR, calculated taking account of the principal contributions to the error (namely, temperature, measurement error, smoothing error) shows that information in the LmT can be achieved by GEO-TIR. We also retrieve analogous profiles from another geostationary infrared instrument with characteristics similar to the Meteosat Third Generation Infrared Sounder (MTG-IRS) which is dedicated to numerical weather prediction, referred to as GEO-TIR2. Comparison between GEO-TIR and GEO-TIR2 allows us to quantify the added value of GEO-TIR, a mission complementing the AQ observing system. To better characterize the information provided by GEO-TIR and GEO-TIR2 in the LmT, we retrieve two typical profiles of O3 and CO for different thermal contrast ranging from –10 K to 10 K. The shape of the first averaging kernel (corresponding to the surface level) confirms that GEO-TIR has good sensitivity to CO in the LmT and also to O3 for high positive thermal contrast. GEO-TIR2 has very low sensitivity in the LmT to O3 but can have sensitivity to CO with high positive thermal contrast. To quantify these results for a realistic atmosphere, we simulate it using the chemical transport model MOCAGE (MOdèle de Chimie Atmospherique à Grande Echelle) – this is the nature run. We simulate the O3 and CO spatial and temporal distributions from GEO-TIR observations in the LmT in July 2009 over Europe by sampling the nature run. Results show that GEO-TIR is able to capture well the spatial and temporal variability in the LmT for both O3 and CO, particularly during periods with high positive thermal contrast near the ground and high surface temperature, which results in active photochemistry and a raised planetary boundary layer. These results also provide evidence of the significant added value in the LmT of GEO-TIR compared to GEO-TIR2 by showing GEO-TIR is closer to the nature run than GEO-TIR2 for various statistical parameters (correlation, bias, standard deviation).
Selection effects in identifying magnetic clouds and the importance of the closest approach parameter
Authors: Lepping R. P. , Wu C.-C.
Published: August 2010

Abstract. This study is motivated by the unusually low number of magnetic clouds (MCs) that are strictly identified within interplanetary coronal mass ejections (ICMEs), as observed at 1 AU; this is usually estimated to be around 30% or lower. But a looser definition of MCs may significantly increase this percentage. Another motivation is the unexpected shape of the occurrence distribution of the observers' "closest approach distances" (measured from a MC's axis, and called CA) which drops off somewhat rapidly as |CA| (in % of MC radius) approaches 100%, based on earlier studies. We suggest, for various geometrical and physical reasons, that the |CA|-distribution should be somewhere between a uniform one and the one actually observed, and therefore the 30% estimate should be higher. So we ask, When there is a failure to identify a MC within an ICME, is it occasionally due to a large |CA| passage, making MC identification more difficult, i.e., is it due to an event selection effect? In attempting to answer this question we examine WIND data to obtain an accurate distribution of the number of MCs vs. |CA| distance, whether the event is ICME-related or not, where initially a large number of cases (N=98) are considered. This gives a frequence distribution that is far from uniform, confirming earlier studies. This along with the fact that there are many ICME identification-parameters that do not depend on |CA| suggest that, indeed an MC event selection effect may explain at least part of the low ratio of (No. MCs)/(No. ICMEs). We also show that there is an acceptable geometrical and physical consistency in the relationships for both average "normalized" magnetic field intensity change and field direction change vs. |CA| within a MC, suggesting that our estimates of |CA|, BO (magnetic field intensity on the axis), and choice of a proper "cloud coordinate" system (all needed in the analysis) are acceptably accurate. Therefore, the MC fitting model (Lepping et al., 1990) is adequate, on average, for our analysis. However, this selection effect is not likely to completely answer our original question, on the unexpected ratio of MCs to ICMEs, so we must look for other factors, such as peculiarities of CME birth conditions. As a by-product of this analysis, we determine that the first order structural effects within a MC due to its interaction with the solar wind, plus the MC's usual expansion at 1 AU (i.e., the non-force free components of the MC's field) are, on average, weakly dependent on radial distance from the MC's axis; that is, in the outer reaches of a typical MC the non-force free effects show up, but even there they are rather weak. Finally, we show that it is not likely that a MC's size distribution statistically controls the occurrence distribution of the estimated |CA|s.
Microbial conversion of inorganic carbon to dimethyl sulfide in anoxic lake sediment (Plußsee, Germany)
Authors: Lin Y. S. , Heuer V. B. , Ferdelman T. G. , Hinrichs K.-U.
Published: August 2010

Abstract. In anoxic environments, volatile methylated sulfides like methanethiol (MT) and dimethyl sulfide (DMS) link the pools of inorganic and organic carbon with the sulfur cycle. However, direct formation of methylated sulfides from reduction of dissolved inorganic carbon has previously not been demonstrated. When studying the effect of temperature on hydrogenotrophic microbial activity, we observed formation of DMS in anoxic sediment of Lake Plußsee at 55 °C. Subsequent experiments strongly suggested that the formation of DMS involves fixation of bicarbonate via a reductive pathway in analogy to methanogenesis and engages methylation of MT. DMS formation was enhanced by addition of bicarbonate and further increased when both bicarbonate and H2 were supplemented. Inhibition of DMS formation by 2-bromoethanesulfonate points to the involvement of methanogens. Compared to the accumulation of DMS, MT showed the opposite trend but there was no apparent 1:1 stoichiometric ratio between both compounds. Both DMS and MT had negative δ13C values of −62‰ and −55‰, respectively. Labeling with NaH13CO3 showed more rapid incorporation of bicarbonate into DMS than into MT. The stable carbon isotopic evidence implies that bicarbonate was fixed via a reductive pathway of methanogenesis, and the generated methyl coenzyme M became the methyl donor for MT methylation. Neither DMS nor MT accumulation were stimulated by addition of the methyl-group donors methanol and syringic acid or by the methyl-group acceptor hydrogen sulphide. The source of MT was further investigated in a H235S labeling experiment, which demonstrated a microbially-mediated process of hydrogen sulfide methylation to MT that accounted for only <10% of the accumulation rates of DMS. Therefore, the major source of the 13C-depleted MT was neither bicarbonate nor methoxylated aromatic compounds. Other possibilities for isotopically depleted MT, such as other organic precursors like methionine, are discussed. This DMS-forming pathway may be relevant for anoxic environments such as hydrothermally influenced sediments and fluids and sulfate-methane transition zones in marine sediments.
Abrupt sea surface pH change at the end of the Younger Dryas in the central sub-equatorial Pacific inferred from boron isotope abundance in corals (Porites)
Authors: Douville E. , Paterne M. , Cabioch G. , Louvat P. , Gaillardet J. , Juillet-Leclerc A. , Ayliffe L.
Published: August 2010

Abstract. The "δ11B-pH" technique was applied to modern and ancient corals Porites from the sub-equatorial Pacific areas (Tahiti and Marquesas) spanning a time interval from 0 to 20.720 calendar years to determine the amplitude of pH changes between the Last Glacial Period and the Holocene. Boron isotopes were measured by Multi-Collector – Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) with an external reproducibility of 0.25‰, allowing a precision of about ±0.03 pH-units for pH values between 8 and 8.3. The boron concentration [B] and isotopic composition of modern samples indicate that the temperature strongly controls the partition coefficient KD for different aragonite species. Modern coral δ11B values and the reconstructed sea surface pH values for different Pacific areas match the measured pH expressed on the seawater scale and confirm the calculation parameters that were previously determined by laboratory calibration exercises. Most ancient sea surface pH reconstructions near Marquesas are higher than modern values. These values range between 8.19 and 8.27 for the Holocene and reached 8.30 at the end of the last glacial period (20.7 kyr BP). At the end of the Younger Dryas (11.50±0.1 kyr BP), the central sub-equatorial Pacific experienced a dramatic drop of up to 0.2 pH-units from the average pH of 8.2 before and after this short event. Using the marine carbonate algorithms, we recalculated the aqueous pCO2 to be 440±25 ppmV at around 11.5 kyr BP for corals at Marquesas and ~500 ppmV near Tahiti where it was assumed that pCO2 in the atmosphere was 250 ppmV. Throughout the Holocene, the difference in pCO2 between the ocean and the atmosphere at Marquesas (ΔpCO2) indicates that the surface waters behave as a moderate CO2 sink or source (−53 to 20 ppmV) during El Niño-like conditions. By contrast, during the last glacial/interglacial transition, this area was a marked source of CO2 (21 to 92 ppmV) for the atmosphere, highlighting predominant La Niña-like conditions. Such conditions were particularly pronounced at the end of the Younger Dryas with a large amount of CO2 released with ΔpCO2 of +185±25 ppmV. This last finding provides further evidence of the marked changes in the surface water pH and temperature in the equatorial Pacific at the Younger Dryas-Holocene transition and the strong impact of oceanic dynamic on the atmospheric CO2 content.
Quantifying wetland methane emissions with process-based models of different complexities
Authors: Tang J. , Zhuang Q. , Shannon R. D. , White J. R.
Published: August 2010

Abstract. Bubbling is an important pathway of methane emissions from wetland ecosystems; however the concentration-based threshold function approach in current biogeochemistry models of methane is not sufficient to represent the complex ebullition process. Here we revise an extant process-based biogeochemistry model, the Terrestrial Ecosystem Model into a multi-substance model (CH4, O2, CO2 and N2) to simulate methane production, oxidation, and transport (particularly ebullition) with different model complexities. When ebullition is modeled with a concentration-based threshold function and if the inhibition effect of oxygen on methane production and the competition for oxygen between methanotrophy and heterotrophic respiration are retained, the model is a two-substance system. Ignoring the role of oxygen, while still modeling ebullition with a concentration-based threshold function, reduces the model to a one-substance system. These models were tested through a group of sensitivity analyses at two temperate peatland sites in Michigan. We demonstrate that only the four-substance model with a pressure-based ebullition algorithm is able to capture the episodic emissions induced by a sudden decrease in atmospheric pressure. All models captured the retardation effect on methane efflux from an increase in surface standing water which results from the inhibition of diffusion and the increase in rhizospheric oxidation. We conclude that to more accurately account for the effects of atmospheric pressure dynamics and standing water on methane effluxes, the multi-substance model with a pressure-based ebullition algorithm should be used in the future to quantify global wetland CH4 emissions. Further, to more accurately simulate the pore water gas concentrations and different pathways of methane transport, an exponential root distribution function should be used and the phase-related parameters should be treated as temperature dependent.
Detection of pore space in CT soil images using artificial neural networks
Authors: Cortina-Januchs M. G. , Quintanilla-Dominguez J. , Vega-Corona A. , Tarquis A. M. , Andina D.
Published: August 2010

Abstract. Computed Tomography (CT) images provide a non-invasive alternative for observing soil structures, particularly pore space. Pore space in soil data indicates empty or free space in the sense that no material is present there except fluids such as air, water, and gas. Fluid transport depends on where pore spaces are located in the soil, and for this reason, it is important to identify pore zones. The low contrast between soil and pore space in CT images presents a problem with respect to pore quantification. In this paper, we present a methodology that integrates image processing, clustering techniques and artificial neural networks, in order to classify pore space in soil images. Image processing was used for the feature extraction of images. Three clustering algorithms were implemented (K-means, fuzzy C-means, and self organizing maps) to segment images. The objective of clustering process is to find pixel groups of a similar grey level intensity and to organise them into more or less homogeneous groups. The segmented images are used for test a classifier. An artificial neural network is characterised by a great degree of modularity and flexibility, and it is very efficient for large-scale and generic pattern recognition applications. For these reasons, an artificial neural network was used to classify soil images into two classes (pore space and solid soil). Our methodology shows an alternative way to detect solid soil and pore space in CT images. The percentages of correct classifications of pore space of the total number of classifications among the tested images were 97.01%, 96.47% and 96.12%.
Changes in flood frequencies in Switzerland since 1500
Authors: Schmocker-Fackel P. , Naef F.
Published: August 2010

Abstract. In northern Switzerland, an accumulation of large flood events has occurred since the 1970s, preceded by a prolonged period with few floods (Schmocker-Fackel and Naef, 2010). How have Swiss flood frequencies changed over the past 500 years? And how does the recent increase in flood frequencies compare with other periods in this half millennium? We collected historical flood data for 14 Swiss catchments dating back to 1500 AC. All catchments experienced marked fluctuations in flood frequencies, and we were able to identify four periods of frequent flooding in northern Switzerland, lasting between 30 and 100 years (1560–1590, 1740–1790, 1820–1940 and since 1970). The current period of increased flood frequencies has not yet exceeded those observed in the past. We tested whether the flood frequency fluctuation could be explained with generalised climatic indices like solar activity or the NAO. The first three periods of low flood frequency in Switzerland correspond to periods of low solar activity. However, after 1810 no relationship between solar activity and flood frequency was found, nor could a relationship be established between reconstructed NAO indices or reconstructed Swiss temperatures. We found re-occurring spatial patterns of flood frequencies on a European scale, with the Swiss periods of frequent flooding often in phase with those in the Czech Republic, Italy and Spain and less often with those in Germany. The pattern of flooding in northern Switzerland and the Czech Republic seem to be rather similar, although the individual flood events do not match. This comparison of flooding patterns in different European countries suggests that changes in large scale atmospheric circulation are responsible for the flood frequency fluctuations.
Streamflow trends in Europe: evidence from a dataset of near-natural catchments
Authors: Stahl K. , Hisdal H. , Hannaford J. , Tallaksen L. M. , van Lanen H. A. J. , Sauquet E. , Demuth S. , Fendekova M. , Jódar J.
Published: August 2010

Abstract. Streamflow observations from near-natural catchments are of paramount importance for detection and attribution studies, evaluation of large-scale model simulations, and assessment of water management, adaptation and policy options. This study investigates streamflow trends in a newly-assembled, consolidated dataset of near-natural streamflow records from 441 small catchments in 15 countries across Europe. The period 1962–2004 provided the best spatial coverage, but analyses were also carried out for longer time periods (with fewer stations), starting in 1932, 1942 and 1952. Trends were calculated by the slopes of the Kendall-Theil robust line for standardized annual and monthly streamflow, as well as for summer low flow and low flow timing. A regionally coherent picture of annual streamflow trends emerged, with negative trends in southern and eastern regions, and generally positive trends elsewhere (especially in northern latitudes). Trends in monthly streamflow for 1962–2004 elucidated potential causes for these changes, as well as other changes observed in hydrological regimes across Europe. Positive trends were found in the winter months in most catchments. A marked shift towards negative trends was observed in April, gradually spreading across Europe to reach a maximum extent in August. Low flows have decreased in most regions where the lowest mean monthly flow occurs in summer, but vary for catchments which have flow minima in winter and secondary low flows in summer. The study largely confirms findings from national and regional scale trend analyses, but clearly adds to these by confirming that these tendencies are part of coherent patterns of change, which cover a much larger region. The broad, continental-scale patterns of change are congruent with the hydrological responses expected from future climatic changes, as projected by climate models. The patterns observed could hence provide a valuable benchmark for a number of different studies and model simulations.
Manufactured analytical solutions for isothermal full-Stokes ice sheet models
Authors: Sargent A. , Fastook J. L.
Published: August 2010

Abstract. We present the detailed construction of a manufactured analytical solution to time-dependent and steady-state isothermal full-Stokes ice sheet problems. The solutions are constructed for two-dimensional flowline and three-dimensional full-Stokes ice sheet models with variable viscosity. The construction is done by choosing for the specified ice surface and bed a velocity distribution that satisfies both mass conservation and the kinematic boundary conditions. Then a compensatory stress term in the conservation of momentum equations and their boundary conditions is calculated to make the chosen velocity distributions as well as the chosen pressure field into exact solutions. By substituting different ice surface and bed geometry formulas into the derived solution formulas, analytical solutions for different geometries can be constructed. The boundary conditions can be specified as essential Dirichlet conditions or as periodic boundary conditions. By changing a parameter value, the analytical solutions allow investigation of algorithms for a different range of aspect ratios as well as for different, frozen or sliding, basal conditions. The analytical solutions can also be used to estimate the numerical error of the method in the case when the effects of the boundary conditions are eliminated, that is, when the exact solution values are specified as inflow and outflow boundary conditions.
The Potsdam Parallel Ice Sheet Model (PISM-PIK) – Part 1: Model description
Authors: Winkelmann R. , Martin M. A. , Haseloff M. , Albrecht T. , Bueler E. , Khroulev C. , Levermann A.
Published: August 2010

Abstract. We present the Potsdam Parallel Ice Sheet Model (PISM-PIK), developed at the Potsdam Institute for Climate Impact Research to be used for simulations of large-scale ice sheet-shelf systems. It is derived from the Parallel Ice Sheet Model (Bueler and Brown, 2009). Velocities are calculated by superposition of two shallow stress balance approximations within the entire ice covered region: the shallow ice approximation (SIA) is dominant in grounded regions and accounts for shear deformation parallel to the geoid. The plug-flow type shallow shelf approximation (SSA) dominates the velocity field in ice shelf regions and serves as a basal sliding velocity in grounded regions. Ice streams naturally emerge through this approach and can be identified diagnostically as regions with a significant contribution of membrane stresses to the local momentum balance. All lateral boundaries in PISM-PIK are free to evolve, including the grounding line and ice fronts. Ice shelf margins in particular are modeled using Neumann boundary conditions for the SSA equations, reflecting a hydrostatic stress imbalance along the vertical calving face. The ice front position is modeled using a subgrid scale representation of calving front motion (Albrecht et al., 2010) and a physically motivated dynamic calving law based on horizontal spreading rates. The model is validated within the Marine Ice Sheet Model Intercomparison Project (MISMIP) and is used for a dynamic equilibrium simulation of Antarctica under present-day conditions in the second part of this paper (Martin et al., 2010).
The Potsdam Parallel Ice Sheet Model (PISM-PIK) – Part 2: Dynamic equilibrium simulation of the Antarctic ice sheet
Authors: Martin M. A. , Winkelmann R. , Haseloff M. , Albrecht T. , Bueler E. , Khroulev C. , Levermann A.
Published: August 2010

Abstract. We present a dynamic equilibrium simulation of the ice sheet-shelf system on Antarctica with the Potsdam Parallel Ice Sheet Model (PISM-PIK). The simulation is initialized with present-day conditions for topography and ice thickness and then run to steady state with constant present-day surface mass balance. Surface temperature and basal melt distribution are parameterized. Grounding lines and calving fronts are free to evolve, and their modeled equilibrium state is compared to observational data. A physically-motivated dynamic calving law based on horizontal spreading rates allows for realistic calving fronts for various types of shelves. Steady-state dynamics including surface velocity and ice flux are analyzed for whole Antarctica and the Ronne-Filchner and Ross ice shelf areas in particular. The results show that the different flow regimes in sheet and shelves, and the transition zone between them, are captured reasonably well, supporting the approach of superposition of SIA and SSA for the representation of fast motion of grounded ice. This approach also leads to a natural emergence of streams in this new 3-D marine ice sheet model.
Roll‐Bonded Titanium/Stainless‐Steel Couples. Part 3: Adhesion Properties
Authors: Dziallach Sebastian , Bleck Wolfgang , Köhler Matthias
Published: August 2010

This work presents adhesion properties of roll‐bonded and heat treated titanium–stainless steel couples determined by means of tensile shear tests and peeling tests. The developed testing methods will be described and the applicability on material couples will be discussed. The determined adhesion forces and resistances were correlated with the interface microstructure of the material couple. Hence, the optimum annealing conditions for maximum adhesion force can be determined. The determined adhesion properties in this paper and the already published results to the diffusion behavior and mechanical properties give important measuring data to make a final evaluation of the material couple with regard to a technical application.
Photonic Crystals in Bioassays
Authors: Zhao Yuanjin , Zhao Xiangwei , Gu Zhongze
Published: August 2010

Photonic crystal (PC) based bioassay techniques have many advantages in sensitive biomolecular screening, label‐free detection, real‐time monitoring of enzyme activity, cell morphology research, and so on. This study provides an overall survey of the basic concepts and up‐to‐date research concerning the very promising use of PC materials for bioassays. It includes the design and application of PC films, PC microcarriers, PC fibers, and PC optofluidics for fluorescence enhancement or label‐free bioassays. Emphasis is given to the description of the functional structures of different PC materials and their respective sensing mechanisms. Examples of detecting various types of analytes are presented. This article promotes communication among chemistry, biology, medicine, pharmacy, and material science.
Self‐Assembled Graphene–Enzyme Hierarchical Nanostructures for Electrochemical Biosensing
Authors: Zeng Qiong , Cheng Jinsheng , Tang Longhua , Liu Xiaofei , Liu Yanzhe , Li Jinghong , Jiang Jianhui
Published: August 2010

The self‐assembly of sodium dodecyl benzene sulphonate (SDBS) functionalized graphene sheets (GSs) and horseradish peroxidase (HRP) by electrostatic attraction into novel hierarchical nanostructures in aqueous solution is reported. Data from scanning electron microscopy, high‐resolution transmission electron microscopy, and X‐ray diffraction demonstrate that the HRP–GSs bionanocomposites feature ordered hierarchical nanostructures with well‐dispersed HRP intercalated between the GSs. UV‐vis and infrared spectra indicate the native structure of HRP is maintained after the assembly, implying good biocompatibility of SDBS‐functionalized GSs. Furthermore, the HRP–GSs composites are utilized for the fabrication of enzyme electrodes (HRP–GSs electrodes). Electrochemical measurements reveal that the resulting HRP–GSs electrodes display high electrocatalytic activity to H2O2 with high sensitivity, wide linear range, low detection limit, and fast amperometric response. These desirable electrochemical performances are attributed to excellent biocompatibility and superb electron transport efficiency of GSs as well as high HRP loading and synergistic catalytic effect of the HRP–GSs bionanocomposites toward H2O2. As graphene can be readily non‐covalently functionalized by “designer” aromatic molecules with different electrostatic properties, the proposed self‐assembly strategy affords a facile and effective platform for the assembly of various biomolecules into hierarchically ordered bionanocomposites in biosensing and biocatalytic applications.
Autonomic Recovery of Fiber/Matrix Interfacial Bond Strength in a Model Composite
Authors: Blaiszik Benjamin J. , Baginska Marta , White Scott R. , Sottos Nancy R.
Published: August 2010

Autonomic self‐healing of interfacial damage in a model single‐fiber composite is achieved through sequestration of ca. 1.5 μm diameter dicyclopentadiene (DCPD) healing‐agent‐filled capsules and recrystallized Grubbs’ catalyst to the fiber/matrix interface. When damage initiates at the fiber/matrix interface, the capsules on the fiber surface rupture, and healing agent is released into the crack plane where it contacts the catalyst, initiating polymerization. A protocol for characterizing the efficiency of interfacial healing for the single‐fiber system is established. Interfacial shear strength (IFSS), a measure of the bond strength between the fiber and matrix, is evaluated for microbond specimens consisting of a single self‐healing functionalized fiber embedded in a microdroplet of epoxy. The initial (virgin) IFSS is equivalent or enhanced by the addition of capsules and catalyst to the interface and up to 44% average recovery of IFSS is achieved in self‐healing samples after full interfacial debonding. Examination of the fracture interfaces by scanning electron microscopy reveals further evidence of a polyDCPD film in self‐healing samples. Recovery of IFSS is dictated by the bond strength of polyDCPD to the surrounding epoxy matrix.
Effects of Thermal Annealing Upon the Morphology of Polymer–Fullerene Blends
Authors: Verploegen Eric , Mondal Rajib , Bettinger Christopher J. , Sok Seihout , Toney Michael F. , Bao Zhenan
Published: August 2010

Grazing incidence X‐ray scattering (GIXS) is used to characterize the morphology of poly(3‐hexylthiophene) (P3HT)–phenyl‐C61‐butyric acid methyl ester (PCBM) thin film bulk heterojunction (BHJ) blends as a function of thermal annealing temperature, from room temperature to 220 °C. A custom‐built heating chamber for in situ GIXS studies allows for the morphological characterization of thin films at elevated temperatures. Films annealed with a thermal gradient allow for the rapid investigation of the morphology over a range of temperatures that corroborate the results of the in situ experiments. Using these techniques the following are observed: the melting points of each component; an increase in the P3HT coherence length with annealing below the P3HT melting temperature; the formation of well‐oriented P3HT crystallites with the (100) plane parallel to the substrate, when cooled from the melt; and the cold crystallization of PCBM associated with the PCBM glass transition temperature. The incorporation of these materials into BHJ blends affects the nature of these transitions as a function of blend ratio. These results provide a deeper understanding of the physics of how thermal annealing affects the morphology of polymer–fullerene BHJ blends and provides tools to manipulate the blend morphology in order to develop high‐performance organic solar cell devices.
An Organic Hole Transport Layer Enhances the Performance of Colloidal PbSe Quantum Dot Photovoltaic Devices
Authors: Kuo Chih‐Yin , Su Ming‐Shin , Hsu Yu‐Chien , Lin Hui‐Ni , Wei Kung‐Hwa
Published: August 2010

A thin poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) hole transport layer enhances the AM1.5 power conversion efficiency of a PbSe quantum dot (QD)–containing photovoltaic device to 2.4%, from 1.5% for a standard PbSe QD device, a relative increase of 60%. Synchrotron X‐ray reflectivity measurements reveal that the roughness of the interfaces between the various layers decreases dramatically in the presence of the PEDOT:PSS layer. In addition, the device life time under continuous simulated AM1.5 irradiation (100 mW cm−2), measured in terms of the time required to reach 80% of the normalized efficiency, for the PbSe QD device incorporating the PEDOT:PSS hole transport layer is six times longer than that of the standard PbSe QD device.