bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of natural killer T cells in lung inflammation
Authors: Boyton R
Published: December 2007

Invariant NK T cells (iNKT) bridge the innate and adaptive immune response, being characterized by the ability to use invariant T cell receptors to recognize glycolipid antigens presented by CD1d, leading to an explosive cytokine effector response. As such it has been proposed that iNKT cells perform important roles as both effector and regulatory cells in a wide range of disease settings. These roles have been characterized in experiments depending on the use of iNKT‐null mice, due to lack of either CD1d expression or Jα18 and the use of CD1d tetramers loaded with the model glycolipid antigen, α‐galactosylceramide (αGalCer). Several studies have examined lung disease, infectious and allergic, in humans and mice. While the lung itself does not carry an exceptionally large population of iNKT cells (compared with, say, the liver), it does appear to be a site at which these cells can exert a profound effect. Several models of bacterial, fungal and viral murine lung infection have been investigated that have sometimes produced conflicting results. Abrogation of iNKT cell function in knockouts is often associated with disease exacerbation, indicating a regulatory role in lung infection. Studies in murine asthma models and in patients have similarly probed the role of iNKT cells in these settings. While there are again somewhat contradictory findings, evidence suggests a likely role for iNKT cells in mediating airway hyper‐responsiveness (AHR), but probably not in Th2 polarization or lung eosinophilia. In marginally different models, administration of αGalCer has either ameliorated or exacerbated AHR. Different studies of BAL from human asthma patients show variously that there is either a very enlarged population of iNKT cells in the asthmatic lung, or that there is no significant difference from controls. Taken together, there are some observations that argue compellingly for an important role of iNKT cells in the lung, but resolution of some of the contradictory findings may await the development of reagents capable of providing alternative readouts of iNKT activation in these diverse disease settings. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Innate immunity in inflammatory bowel disease: a disease hypothesis
Authors: Marks DJB , Segal AW
Published: December 2007

Crohn's disease arises from a defective interaction between the highly concentrated mass of bacteria in the gastrointestinal tract and the underlying tissues. It has generally been believed to result from an excessively exuberant inflammatory response or from ‘autoimmunity’. Recent evidence has emerged that the problem is instead a failure of the way in which the body responds to the penetration of bacteria and other bowel contents through the intestinal mucosal barrier. Rather than Crohn's disease being caused by excessive inflammation, the primary mechanism is actually that of an immunodeficiency. Failure of inflammatory mediator production leads to insufficient recruitment of neutrophils, resulting in inadequate removal of bacteria and other debris. This impairment of acute inflammation can be compensated in some circumstances by signalling through NOD2. If not cleared, the foreign material in the bowel wall is taken up within macrophages, eliciting a granulomatous reaction and the local and systemic sequelae so characteristic of Crohn's disease. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Molecular and cellular themes in inflammation and immunology
Authors: Herrington CS , Hall PA
Published: December 2007

This issue of the Journal of Pathology contains a series of cutting‐edge review articles that deal with the broad issue of inflammatory and immunological disease mechanisms. Of necessity, these reviews deal with selected topics but the mixture of articles on specific signalling pathways and mediators with articles addressing individual organ systems provides a broad overview of the field. These contributions provide insight into current areas of debate in inflammation and immunology. In particular, they highlight current interest in the interface between innate and adaptive immunity and present intriguing prospects for future therapeutic developments in a variety of disease areas. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Development of nonlinear constitutive laws for anisotropic and asymmetric fiber reinforced composites
Authors: Kim Ji Hoon , Lee Myoung‐Gyu , Ryou Hansun , Chung Kwansoo , Youn Jae Ryoun , Kang Tae Jin
Published: December 2007

A plane‐stress constitutive law was developed to describe the inelastic nonlinear, anisotropic, and asymmetric mechanical behavior of fiber reinforced composites under the elasto‐plasticity framework, in particular, based on the kinematic hardening model. A yield criterion that describes anisotropic and asymmetric yield behavior was proposed, while the anisotropic translation of the yield surface was assumed to account for the directional difference of hardening behavior. The proposed constitutive equation was then implemented into the commercial FE program ABAQUS with the aid of the user material subroutine. Experimental procedures to characterize the material parameters of the proposed constitutive equation were presented for 3D braided glass/Kevlar fiber reinforced composites. Verification performed for three point bending tests showed good agreements. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers
Fiber orientation in injection molding with rotating flow
Authors: Silva Cristina A. , Viana Júlio C. , van Hattum Ferrie W.J. , Cunha António M.
Published: December 2007

The development of fiber orientation in injection molding was manipulated by a special molding tool, the RCEM mold, which imposes a rotation action by one of the cavity surfaces during the filling stage. Center‐gated disc moldings were produced from glass fiber reinforced polypropylene with different cavity rotation velocities, inducing distinct distributions and levels of fiber orientation. The morphologies of the moldings were characterized by optical and electronic microscopy. The through‐thickness profiles of fiber orientation were assessed by means of the orientation tensor, and the relationship between the processing thermo‐mechanical environment and the fiber orientation was established. At high rotation velocities, the resulting fiber orientation pattern is mainly controlled by the rotational motion, inducing a much more homogeneous through‐the‐thickness fiber orientation distribution, with a preferential alignment on the circumferential direction. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Influence of molecular weight on the electrification of linear polyethylenes during extrusion: Identification of two different mechanisms for charge generation
Authors: Rodríguez‐González Francisco , Pérez‐González José , de Vargas Lourdes , Moreno Edgard , González‐Santos Germán
Published: December 2007

The phenomenon of electrification is the accumulation of electric charge in a material. Polymers may become electrified when subjected to intense friction during their processing or under working conditions and the accumulated electric charge may change their adhesion and friction properties. In this work, a study of the influence of molecular weight and chain mobility on the electrification of linear low‐density polyethylenes under continuous extrusion is presented. The use of different die materials, polymer processing additives, as well as slip and no slip flow conditions allowed the identification of two different mechanisms for electric charge generation in the melts; namely, the stripping of an electrical double layer acting in the absence of slip, and dynamic frictional electrification, or tribocharging acting under strong slip conditions. The magnitude of the electric charge was found to increase with polymer molecular weight and die length, and exhibited a local maximum as a function of the average velocity of the melt in both cases. The height of the maximum increased along with the molecular mobility. The experimental results were compared with the numerical solution of the equation of continuity for charge transport and it is shown that it does not describe the experimental results because it does not consider the additional mechanism of charge generation introduced by strong slip at the die wall. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Reversible thermal gelation of soft semi‐crystalline polyethylene microparticles with surface interactions in squalane
Authors: Ling Gerald H. , Shaw Montgomery T.
Published: December 2007

The effect of temperature on the steady‐shear viscosity of a soft semi‐crystalline crosslinked‐polyethylene microparticle suspension in squalane was studied using rotational rheometry. The results show a sharp increase in the viscosity of the system occurring at about 86°C. The magnitude of this spike is dependent on the concentration of the suspension and is reproducible over multiple heating and cooling cycles. This phenomenon has been attributed to the melting of the crystalline regions within the particles, causing them to swell by soaking up squalane. The Mooney equation was used to model the viscosity data based on swelling data obtained from separate experiments. The results showed that the model is inadequate for describing the observed phenomenon, suggesting the possibility of additional interactions existing among the particles. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Conventional and nanometric nucleating agents in poly(ϵ‐caprolactone) foaming: Crystals vs. bubbles nucleation
Authors: Marrazzo Carlo , Di Maio Ernesto , Iannace Salvatore
Published: December 2007

The aim of this article was to investigate the nucleating ability of different nucleating agents for the foaming of poly(ε‐caprolactone), a biodegradable, semicrystalline polymer. In particular, the efficiency of the nucleating agent in inducing the formation of the gaseous phase has been compared to the efficiency in inducing the formation of the crystalline phase. In effect, in foaming of semicrystalline polymers, bubble nucleation and crystal nucleation are concurrent and somehow interacting phenomena. Here, these two aspects have been evidenced and clarified. Foams were prepared by using a batch process with the pressure quench method, with nitrogen and carbon dioxide as the blowing agents. Conventional and novel nucleating agents were used: talc has been compared to several novel nanometric particles of different geometries and dimensions, such as titanium dioxide and alumina powders, exfoliated and intercalated clays, and carbon nanotubes. Foam densities and morphologies, in terms of number of cells per initial unit volume, were measured and found to depend both on crystalline phase nucleation and gaseous phase nucleation. In fact, the different nucleating agents, depending on shape, dimension, and surface functionalization, selectively nucleated the crystallites and/or the bubbles, affecting, respectively, bubble growth (and, hence, final foam density) and bubble nucleation (and, hence, cell number density—morphology). POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Sharkskin and oscillating melt fracture: Why in slit and capillary dies and not in annular dies?
Authors: Delgadillo‐Velázquez O. , Georgiou G. , Sentmanat M. , Hatzikiriakos S.G.
Published: December 2007

The sharkskin and stick‐slip polymer extrusion instabilities are studied primarily as functions of the type of die geometry. Experimental observations concerning the flow curves, the critical wall shear stress for the onset of the instabilities, the pressure and flow rate oscillations, and the effects of geometry and operating conditions are presented for linear low‐density polyethylenes. It is found that sharkskin and stick‐slip instabilities are present in the capillary and slit extrusion. However, annular extrusion stick‐slip and sharkskin are absent at high ratios of the inside‐to‐outside diameter of the annular die. This observation also explains the absence of these phenomena in other polymer processing operations such as film blowing. These phenomena are explained in terms of the surface‐to‐volume ratio of the extrudates, that is, if this ratio is high, sharkskin and stick‐slip are absent. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Electromagnetic interference shielding with polyaniline nanofibers composite coatings
Authors: Niu Yuhua
Published: December 2007

Hydrochloric acid doped polyaniline (PANI) nanofibers were synthesized by an interfacial polymerization with tetrachloride as the organic solvent and with a relatively higher aniline concentration. The doped PANI nanofibers were dispersed in cyclohexanone and the dispersion was mixed with solution of polyacrylate to prepare PANI nanofibers composite coatings. It was found that the yield of the doped PANI nanofibers can be as high as 23%, though a small amount of irregular shaped PANI particles and PANI nanofibers with relatively larger diameter were also obtained. The conductivity of the PANI nanofibers based composite coatings increased with the PANI nanofibers contents and a percolation threshold of 0.2 was demonstrated. The shielding effectiveness of the PANI nanofibers based coatings increased with PANI nanofibers loadings and shielding effectiveness as high as 63 dB can be achieved with PANI nanofibers loadings of 45%. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Prediction of environmental stress cracking resistance in linear low density polyethylenes
Authors: Maxwell Antony S. , Pilkington Gordon
Published: December 2007

Recently it has been shown that the strain hardening modulus (Gp) at 80°C can be used to predict the environmental stress cracking (ESC) resistance of polyethylenes. The advantage of using strain hardening to determine ESC resistance is that the data may be obtained relatively easily and quickly using simple tensile test equipment. In this article, the strain hardening modulus has been used to predict the ESC resistance of three grades of linear low‐density polyethylene. Unlike in the previous research, the measurements were conducted at room temperature enabling tests to be performed without the need of a temperature‐controlled oven. This was achieved by reducing the strain rate to increase the sensitivity of the technique and increasing the thickness of the specimens to improve the repeatability. The strain hardening modulus data were found to correlate well with the ESC results obtained from long‐term full notch creep tests and are consistent with the known molecular structure of the polyethylene grades. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Weathering of recycled photo‐degraded polyethylene
Authors: Maxwell A.S.
Published: December 2007

The increased use of recycled plastics in a wide range of outdoor applications depends on the long‐term performance of the material. However, to date most research has been concerned with the effects that recycling has on the immediate mechanical properties of the polymer. The following paper examines the effects that recycling photo‐degraded polymer has on the long‐term photo‐stability of the recycled material. Two identical high‐density polyethylene wheelie‐bins were used in this study, one of which had been kept in a controlled indoor environment and the other kept outdoors for 12years in the United Kingdom. Material removed from each wheelie‐bin was reprocessed and molded into specimens, which were artificially weathered in a Xenon arc chamber. Infrared spectroscopy and nanoindentation revealed that although the properties of each set of specimens were similar immediately after reprocessing, those that had been subjected to outdoor exposure prior to reprocessing degraded more rapidly. This accelerated degradation is believed to be due to the photo‐degraded products in the recycled material accelerating the degradation process. The consequences of this accelerated degradation raise issues regarding the vulnerability of recycled material to the long‐term effects of outdoor exposure. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Viscoelastic evaluation of effects of fiber size and composition on cellulose‐polypropylene composite of high filler content
Authors: Ito Hirokazu , Kumari Rashmi , Takatani Masahiro , Okamoto Tadashi , Hattori Hidehiro , Fujiyoshi Ippei
Published: December 2007

In wood/plastic composite of high wood filler content, filler dispersion in resin is important which determines mobility of compound and mechanical properties of products. This work reports on the dispersion of components in compound by evaluation of viscoelasticity using a cone rheometer. The effects of size of cellulose fiber and resin content on viscoelasticity were analyzed, and the dispersion of cellulose is discussed to reach the following conclusions: The viscoelasticity measured by a cone rheometer was dependent on the dispersion state of compound, and evaluation of viscoelasticity affords the evidence for dispersion state of filler in compound; On the basis of viscoelastic evaluation of compound with different resin content, a model for dispersion of cellulose and resin with tangle of fiber is proposed; Viscoelastic analysis showed that cellulose size has influence on tangle of fiber, and results of viscoelasticity and mechanical properties of mold products suggested that an important factor determining tangle of fiber is its average aspect ratio. The proposed analysis of viscoelasticity presents a new technique for estimating the dispersion state of compound of high filler content which is hardly accessible by conventional fluid evaluation methods. The present method is simple and useful for quality control in manufacture. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Machining of plastics: A new approach for modeling
Authors: Quadrini F.
Published: December 2007

A theoretical model was defined to predict cutting forces in drilling of polyamide. This model was not built in analogy to metal cutting but starting from the viscoelastic behavior of the workpiece material. The drilling thrust and torque were assumed to be a logarithmic function of the ratio between a characteristic time of the material and a process time. Drilling tests were carried out to experimentally evaluate the thrust and torque in dependence of drilling speed and feed rate. The experimental data are in good agreement with the predicted logarithmic trend, except at high feed rates at which a plateau is observed. The chip formation mechanism was recognized to affect the thrust and torque dependence on feed rate so that the theoretical model was opportunely corrected. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Engaging students in inquiry: Tales from an undergraduate geology laboratory‐based course
Authors: Apedoe Xornam S.
Published: December 2007

This paper reports the synthesis of three case studies of students' engagement in inquiry‐based learning activities in an upper‐level undergraduate geology course. Details of how students engaged in scientific questions, gave priority to evidence, formulated explanations, evaluated explanations, and communicated and justified their findings are presented. Data for this study included classroom observations and fieldnotes of classroom practices, questionnaires, archival data (e.g., student work samples), and audiotapes and transcripts of interviews conducted with the student participants throughout the course. The findings suggest that although these students were able to successfully appropriate inquiry practices (e.g., giving priority to evidence), it was not without its challenges (e.g., perceived lack of guidance). A detailed discussion of the ways in which students were successful, and where they had challenges engaging in inquiry is presented, with the goal of helping direct practitioners and researchers to strategies whereby students' inquiry experiences can be improved. © 2007 Wiley Periodicals, Inc. Sci Ed 92:631–663, 2008
Urban elementary school teachers' knowledge and practices in teaching science to English language learners
Authors: Lee Okhee , Lewis Scott , Adamson Karen , Maerten‐Rivera Jaime , Secada Walter G.
Published: December 2007

This study examined urban elementary teachers' knowledge and practices in teaching science while supporting English language development of English language learning (ELL) students. As part of a larger 5‐year research project in the United States, the study involved 38 third‐grade teachers who participated in the first‐year implementation of a professional development intervention that consisted of curriculum units and teacher workshops. The study examined four areas—teacher knowledge of science content, teaching science for understanding, teaching science for inquiry, and teacher support for English language development—through a questionnaire, classroom observations, and postobservation interviews. Results indicate that teachers' knowledge and practices were generally within the bounds supported by the intervention; however, such knowledge and practices fell short of the goal of reform‐oriented practices. The results provide insights for our ongoing intervention and other similar efforts and contribute to the emerging knowledge base on science and English language and literacy with ELL students. © 2007 Wiley Periodicals, Inc. Sci Ed 92:733–758, 2008
Scientific discourse in the academy: A case study of an American Indian undergraduate
Authors: Brandt Carol B.
Published: December 2007

This case study explores how an American Indian woman experienced scientific discourse and the issues of language, power, and authority that occurred while she was an undergraduate student at a university in the southwestern United States. This ethnographic research, using a phenomenological perspective, describes her experiences as she searched for the discursive resources she required to cross‐cultural borders between her traditional worldview and Eurocentric science. Data from interviews, participant observation, and artifacts offer a narrative of how she became aware of the “game rules” of scientific discourse. The findings are expressed in terms of a cartographic metaphor where the student's world became less of a list of categories and more of a map outlining where she ventured and the ways in which she oriented herself to scientific language. To facilitate the border crossing and reduce the obstacles that some students experience in crossing between worldviews, educators can look at cross‐cultural perspectives and explore with students how language fosters or hinders their progress. This research suggests that we allow room in our pedagogy for students to learn the rules of using scientific language, make explicit the cultural norms associated with this practice, thereby promoting a “metaknowledge” of how scientific discourse functions in the academy. © 2007 Wiley Periodicals, Inc. Sci Ed 92:825–847, 2008
Preparing small software companies for tailored agile method adoption: Minimally intrusive risk assessment
Authors: Taylor Philip S. , Greer Des , Coleman Gerry , McDaid Kevin , Keenan Frank
Published: December 2007

There is often a misconception that adopting and tailoring agile methods is straightforward resulting in improved products and increasingly satisfied customers. However, the empirical nature of agile methods means that potential practitioners need to carefully assess whether they are exposed to the risks that can make agile method adoption problematic. This is particularly the case with small software companies who are less able to absorb the impact of failed experimentation. This study describes a minimally intrusive assessment approach for small software companies preparing for agile method adoption and tailoring in the light of key risks. The approach has been conducted with six small software companies, three of which are presented to show the evolution of the approach, describe the resource commitment that companies have to make, and highlight the type of information generated from an assessment. The contribution of this study is that small software companies have an alternative to ‘mere experimentation’ with agile methods and can take reasoned steps towards their adoption and tailoring. Copyright © 2008 John Wiley & Sons, Ltd.
Application of energy capacitor system to wind power generation
Authors: Muyeen S. M. , Shishido S. , Ali Mohd. Hasan , Takahashi Rion , Murata Toshiaki , Tamura Junji
Published: December 2007

In this paper, it is reported that energy capacitor system (ECS), which combines power electronic devices and electric double‐layer capacitor, can significantly decrease voltage and power fluctuations of grid‐connected fixed‐speed wind generator. The proper selection of wind farm output power reference is still a problem for smoothing the wind farm output power. This paper proposes exponential moving average to generate the reference output power of a grid‐connected wind farm. The objective of the control system is to follow the line power reference by absorbing or providing real power to or from the ECS. Moreover, the necessary reactive power can also be supplied to keep the wind farm terminal voltage at the desired reference level. Real wind speed data were used in the simulation analyses, which validate the effectiveness of the proposed control strategy. Simulation results clearly show that our proposed ECS can be suitable for wind power application. Copyright © 2007 John Wiley & Sons, Ltd.
Intervening Processes Between Youths’ Exposure to Community Violence and Internalizing Symptoms Over Time: The Roles of Social Support and Coping
Authors: Rosario Margaret , Salzinger Suzanne , Feldman Richard S. , Ng-Mak Daisy S.
Published: December 2007

The roles of social support and coping as intervening processes between exposure to community violence and internalizing symptoms were examined longitudinally among a community sample of 667 middle school students in the inner city. After controlling for potential confounders (e.g., social desirability, victimization and witnessing of family violence, guardian's psychological symptomatology), internalizing symptoms at Year 2 were predicted by hypothesized changes over 1 year, such that increased community violence exposure, decreased guardian and peer support, and increased use of defensive and confrontational behavioral coping were related to more internalizing symptoms of anxiety, depression and PTSD, although some of these relations varied by gender. The relations between internalizing symptoms at Year 3 and increased changes in exposure to community violence over 2 years were moderated by social support and/or coping, such that decreased guardian support and increased use of defensive and confrontational coping were generally associated with more symptoms for boys exposed to community violence. Girls who witnessed increased community violence and who increased their use of defensive or confrontational coping experienced more internalizing symptoms. The findings underscore the importance of developmental and contextual considerations in the design and implementation of interventions.
Earth‐emitted irradiance near the first Lagrangian point
Authors: Smith G. Louis
Published: December 2007

The first Lagrangian point, L‐1, is a point between the Earth and the Sun where a mass will be in equilibrium between the gravitational pulls of Earth and Sun and its centrifugal force about the center of mass of the Earth‐Sun system. DSCOVER, the first spacecraft planned for Earth observation near L‐1, includes a radiometer to measure shortwave and longwave flux from the full disc of the Earth. The latitude of the subsatellite point is near the solar declination, and its longitude is near that for local noon. The spacecraft is always over the tropics. Moreover, it is always over the summer hemisphere. Both of these effects will cause the full‐disc measurement of Earth‐emitted radiation to be higher than the global mean. In this paper we compute the longwave flux near L‐1 using deconvolution theory for wide field‐of‐view radiometer measurements of Earth‐emitted radiation, which makes the computations simple and provides a theoretical framework for understanding the results. The bias due to being over the summer hemisphere will peak twice during the year, so that a semiannual cycle will occur. The global mean Earth‐emitted radiation has an annual cycle due to the variation of Earth‐Sun distance. If the spacecraft orbit is less than 10° from the Earth‐Sun line, the bias to the global mean is computed to be about 8 W m−2 for the annual average with a semiannual cycle of about 1.5 W m−2. In addition to the seasonal cycles, there is a diurnal cycle in the measurement at L‐1 as the Earth rotates.
Vegetation and topographic control of cloud activity over arid/semiarid Asia
Authors: Sato Tomonori , Kimura Fujio , Hasegawa Akira S.
Published: December 2007

Cloud patterns over arid/semi‐arid area in the Northeast Asia are investigated by statistical analysis of the satellite observations in relation to the roles of topography and vegetation contrasts. In the morning, cloud frequencies are high over the mountainous areas in the northern Mongolia. In the afternoon and early evening, the frequencies increase in the entire analyzed domain. The frequencies are prominently enhanced over the slopes and mountains. The upslope wind prevails during the daytime where vegetation contrasts are not sharp or the slope is steep, even though vegetation covers the mountain which tends to cool the mountain slope. The land‐cover‐induced cloud formations are distinctly observed where the slope is gentle and vegetation contrast is sharp enough to form a prominent surface temperature contrast. Around the Yellow River, the cloud frequency rapidly increases in the afternoon due to the vegetation contrast, whereas it remains very low over the river. We hypothesized that the smaller sensible heat flux from the vegetated surface suppresses the development of the daytime mixed layer. Thus the cumulus clouds near top of the mixed layer are difficult to form. It is inferred from the statistical analysis that the afforestation of the desertified lands may cause the decrease of cloud frequency above it.
Seasonal variations of atmospheric C2–C7 nonmethane hydrocarbons in Tokyo
Authors: Shirai Tomoko , Yokouchi Yoko , Blake Donald R. , Kita Kazuyuki , Izumi K. , Koike M. , Komazaki Y. , Miyazaki Y. , Fukuda M. , Kondo Y.
Published: December 2007

Eighteen C2–C7 NMHCs (nonmethane hydrocarbons) were measured hourly during the Integrated Measurement Program for Aerosol and Oxidant Chemistry in Tokyo (IMPACT) measurement campaigns conducted in central Tokyo during four different periods (summer/autumn of 2003 and winter/summer of 2004). The ambient atmospheric concentrations of NMHCs showed an inverse correlation with wind speed and mixing height and were significantly affected by mesoscale weather conditions. The mixing ratio of isoprene tightly correlated with solar flux and temperature in summer, as it was dominantly emitted by the local vegetation. All the observed NMHCs except isoprene showed high correlation with each other in winter (r2 > 0.5), suggesting concurrent accumulation under stagnant condition and common sources. Emission ratios were calculated on the basis of the correlation with carbon monoxide and ethyne. Compared to the typical winter NMHC composition, during summer there was a significant increase (up to 7 times higher than wintertime) of C4–C5 alkanes from fuel evaporation; of C2–C3 alkenes, n‐hexane and benzene from chemical industry; and of toluene from local manufacturers, reflecting the temperature dependence of these evaporative emissions. In addition to the online measurements in Tokyo, canister sampling at a suburban site (Kisai) followed by multidimensional GC analyses was conducted during the summer campaign in 2004. The atmospheric concentrations of longer‐lived compounds (≥ several days) at Kisai showed the buildup under sea breeze circulation. The average ambient concentration of toluene was 2 times higher than that in central Tokyo, likely because of substantial emissions from local industries as reported in the prefectural statistics.
Drivers of fire in the boreal forests: Data constrained design of a prognostic model of burned area for use in dynamic global vegetation models
Authors: Crevoisier Cyril , Shevliakova Elena , Gloor Manuel , Wirth Christian , Pacala Steve
Published: December 2007

Boreal regions are an important component of the global carbon cycle because they host large stocks of aboveground and belowground carbon. Since boreal forest evolution is closely related to fire regimes, shifts in climate are likely to induce changes in ecosystems, potentially leading to a large release of carbon and other trace gases to the atmosphere. Prediction of the effect of this potential climate feedback on the Earth system is therefore important and requires the modeling of fire as a climate driven process in dynamic global vegetation models (DGVMs). Here, we develop a new data‐based prognostic model, for use in DGVMs, to estimate monthly burned area from four climate (precipitation, temperature, soil water content and relative humidity) and one human‐related (road density) predictors for boreal forest. The burned area model is a function of current climatic conditions and is thus responsive to climate change. Model parameters are estimated using a Markov Chain Monte Carlo method applied to on ground observations from the Canadian Large Fire Database. The model is validated against independent observations from three boreal regions: Canada, Alaska and Siberia. Provided realistic climate predictors, the model is able to reproduce the seasonality, intensity and interannual variability of burned area, as well as the location of fire events. In particular, the model simulates well the timing of burning events, with two thirds of the events predicted for the correct month and almost all the rest being predicted 1 month before or after the observed event. The predicted annual burned area is in the range of various current estimates. The estimated annual relative error (standard deviation) is twelve percent in a grid cell, which makes the model suitable to study quantitatively the evolution of burned area with climate.
Parameter estimation for a physics‐based distributed hydrologic model using measured outflow fluxes and internal moisture states
Authors: Kampf Stephanie K. , Burges Stephen J.
Published: December 2007

We use an inverse simulation strategy to estimate soil hydraulic parameter values for an extensively measured planar hillslope plot in Seattle, Washington, United States. Both the integrated (subsurface outflow) and internal (piezometer water levels, volumetric water contents) hydrologic responses are measured at the plot. Inverse simulation scenarios are configured in the physics‐based variably saturated hydrologic model, HYDRUS‐2D, for a nonhysteretic drainage scenario starting from saturated initial conditions. Multiple inverse simulations calibrate the model either to single‐measurement time series or to combinations of multiple types of measurements. Inverse simulations calibrated to different types of measurements give a wide range of parameter combinations, including over 2 orders of magnitude in predicted saturated hydraulic conductivity (Ks), in part because the calibrations to a single measurement type are poorly constrained and biased. Parameter values are better constrained with multiobjective inverse simulations (Ks from 30 to 55 cm h−1). All parameter combinations from inverse simulations were tested in 2‐month‐long continuous simulations of the plot flow response to natural precipitation and evapotranspiration. The long‐term outflow response was predicted best (Nash‐Sutcliffe E = 0.94) by the parameters from a multiobjective inverse simulation calibrated to both the outflow and the piezometer water levels. Overall results show that for an assumed nonhysteretic soil a physics‐based hydrologic response model can be calibrated using one short‐duration drainage‐from‐saturation event if both integrated (outflow) and internal (saturated water level) measurements are used as calibration objectives.
Triggering mechanism and tsunamogenic potential of the Cape Fear Slide complex, U.S. Atlantic margin
Authors: Hornbach Matthew J. , Lavier Luc L. , Ruppel Carolyn D.
Published: December 2007

Analysis of new multibeam bathymetry data and seismic Chirp data acquired over the Cape Fear Slide complex on the U.S. Atlantic margin suggests that at least 5 major submarine slides have likely occurred there within the past 30,000 years, indicating that repetitive, large‐scale mass wasting and associated tsunamis may be more common in this area than previously believed. Gas hydrate deposits and associated free gas as well as salt tectonics have been implicated in previous studies as triggers for the major Cape Fear slide events. Analysis of the interaction of the gas hydrate phase boundary and the various generations of slides indicates that only the most landward slide likely intersected the phase boundary and inferred high gas pressures below it. For much of the region, we believe that displacement along a newly recognized normal fault led to upward migration of salt, oversteepening of slopes, and repeated slope failures. Using new constraints on slide morphology, we develop the first tsunami model for the Cape Fear Slide complex. Our results indicate that if the most seaward Cape Fear slide event occurred today, it could produce waves in excess of 2 m at the present‐day 100 m bathymetric contour.
A time series of hydroxylamine (NH2OH) in the southwestern Baltic Sea
Authors: Schweiger Bianca , Hansen Hans Peter , Bange Hermann W.
Published: December 2007

Hydroxylamine (NH2OH) is an intermediate of the marine nitrogen cycle and in marine environments dissolved NH2OH is short‐lived. In order to investigate the distribution of NH2OH under varying oxygen conditions, its seasonal variability was investigated on a monthly basis from July 2005 to May 2006 at the time series station Boknis Eck located in the Eckernförde Bay (southwestern Baltic Sea). NH2OH concentrations were generally low and close to the detection limit. However, a pronounced increase was observed after the seasonal thermohaline stratification period with low oxygen/anoxic conditions in the deep layers was terminated in November 2005. The increase of NH2OH was associated with the re‐oxygenation of the water column. We conclude that NH2OH was produced in‐situ during nitrification. We suggest that the detection of significant amounts of NH2OH can be used as an indicator for a “fresh” nitrifying system.
Note on the NDVI‐LST relationship and the use of temperature‐related drought indices over North America
Authors: Sun Donglian , Kafatos Menas
Published: December 2007

A comprehensive evaluation of the relationship between vegetation and Land Surface Temperature (LST) over the North America is presented. It is found that the correlations between LST and Normalized Difference Vegetation Index (NDVI) depend on the season‐of‐year and time‐of‐day. For winter, the correlation between NDVI and LST is positive. The strong negative correlations between LST and NDVI are only found during the warm seasons. Thus temperature‐related drought indices may only be used in the warm seasons from May to October, and should be used with caution during cold seasons in North America. The cooling effect of vegetation on LST is stronger during daytime than nighttime. Moreover, the negative correlations between NDVI and LST are much stronger than those between NDVI and the brightness temperature. Therefore using daytime LST for drought monitoring should be more reasonable than using brightness temperature or nighttime LST.
Condensed‐phase nitric acid in a tropical subvisible cirrus cloud
Authors: Popp P. J. , Marcy T. P. , Watts L. A. , Gao R. S. , Fahey D. W. , Weinstock E. M. , Smith J. B. , Herman R. L. , Troy R. F. , Webster C. R. , Christensen L. E. , Baumgardner D. G. , Voigt C. , Kärcher B. , Wilson J. C. , Mahoney M. J. , Jensen E. J. , Bui T. P.
Published: December 2007

In situ observations in a tropical subvisible cirrus cloud during the Costa Rica Aura Validation Experiment on 2 February 2006 show the presence of condensed‐phase nitric acid. The cloud was observed near the tropopause at altitudes of 16.3–17.7 km in an extremely cold (183–191 K) and dry (<5 ppm H2O) air mass. Relative humidities with respect to ice ranged from 150–250% throughout most of the cloud. Optical particle measurements indicate the presence of ice crystals as large as 90 μm in diameter. Condensed HNO3/H2O molar ratios observed in the cloud particles were 1–2 orders of magnitude greater than ratios observed previously in cirrus clouds at similar HNO3 partial pressures. Nitric acid trihydrate saturation ratios were 10 or greater during much of the cloud encounter, indicating that HNO3 may be present in the cloud particles as a stable condensate and not simply physically adsorbed on or trapped in the particles.
Influence of ocean freshening on shelf phytoplankton dynamics
Authors: Ji Rubao , Davis Cabell S. , Chen Changsheng , Townsend David W. , Mountain David G. , Beardsley Robert C.
Published: December 2007

Climate change‐induced freshening of the ocean can enhance vertical stratification and alter circulation patterns in ways that influence phytoplankton dynamics. We examined the timing of spring phytoplankton blooms and the magnitude of net primary productivity in the Nova Scotian Shelf (NSS) ‐ Gulf of Maine (GoM) region with respect to seasonal and interannual changes in surface water freshening from 1998 to 2006. The general pattern of temporal westward progression of the phytoplankton bloom corresponds with the gradient of increasing sea surface salinity from the NSS in the east to the western GoM. Increased freshening enhances the spatial gradients in bloom timing by stimulating earlier blooms upstream (NSS), but it has less impact downstream (the western GoM). Strong spatial gradients (increasing westward) of mean chlorophyll concentration and net primary productivity during post‐bloom months (May–June) indicate that lower sea surface salinity upstream can likely impede nutrient fluxes from deep water and therefore affect overall productivity.
Comparison of very long baseline interferometry, GPS, and satellite laser ranging height residuals from ITRF2005 using spectral and correlation methods
Authors: Collilieux X. , Altamimi Z. , Coulot D. , Ray J. , Sillard P.
Published: December 2007

For the first time, the ITRF2005 input data are in the form of time series of station positions and Earth orientation parameters, together with full variance‐covariance information. The first step of the ITRF2005 analysis consists of rigorously stacking each time series to yield a long‐term solution per technique. As a by‐product, time series of position residuals contain the nonlinear motion of points over the Earth's surface. In this paper, the height residual time series of very long baseline interferometry (VLBI), Global Positioning System (GPS), and satellite laser ranging (SLR) solutions submitted to ITRF2005 are compared. We note that the interpretation of the ITRF2005 position residual time series as observed physical motions at the various stations is delicate due to the inhomogeneous site distribution. We estimate that the network effect may introduce an averaged scatter of 3 and 2 mm in the VLBI and SLR height residuals, respectively. Although noise levels are different among these three techniques, a common 1.0 cycles per year (cpy) frequency is clearly detected. The GPS height annual signal exhibits significant regional correlations that are confirmed by VLBI and SLR measurements in some colocated sites. Significant power near frequencies 2.00, 3.12, and 4.16 cpy is also detected in the individual GPS height residuals time series as mentioned by Ray et al. (2007). However, neither VLBI nor SLR show any significant signals at these frequencies for colocated sites. The agreement between detrended height time series at colocated sites is quantified using a novel method based on Kalman filtering and on maximum likelihood estimation. The GPS and VLBI measurements are shown to agree fairly well for most of the colocated sites. However, agreement is not generally observed in the GPS and SLR comparisons. A study of the interannual signal at colocated sites indicates that the good correlation cannot be completely attributed to the annual harmonic.
Thermal monitoring of hydrothermal activity by permanent infrared automatic stations: Results obtained at Solfatara di Pozzuoli, Campi Flegrei (Italy)
Authors: Chiodini G. , Vilardo G. , Augusti V. , Granieri D. , Caliro S. , Minopoli C. , Terranova C.
Published: December 2007

A permanent automatic infrared (IR) station was installed at Solfatara crater, the most active zone of Campi Flegrei caldera. After a positive in situ calibration of the IR camera, we analyze 2175 thermal IR images of the same scene from 2004 to 2007. The scene includes a portion of the steam heated hot soils of Solfatara. The experiment was initiated to detect and quantify temperature changes of the shallow thermal structure of a quiescent volcano such as Solfatara over long periods. Ambient temperature is the main parameter affecting IR temperatures, while air humidity and rain control image quality. A geometric correction of the images was necessary to remove the effects of slow movement of the camera. After a suitable correction the images give a reliable and detailed picture of the temperature changes, over the period October 2004 to January 2007, which suggests that origin of the changes were linked to anthropogenic activity, vegetation growth, and the increase of the flux of hydrothermal fluids in the area of the hottest fumaroles. Two positive temperature anomalies were registered after the occurrence of two seismic swarms which affected the hydrothermal system of Solfatara in October 2005 and October 2006. It is worth noting that these signs were detected in a system characterized by a low level of activity with respect to systems affected by real volcanic crisis where more spectacular results will be expected. Results of the experiment show that this kind of monitoring system can be a suitable tool for volcanic surveillance.