bluuebunny/crossref_metadata_2025 huggingface dataset:
Size and time-resolved roadside enrichment of atmospheric particulate pollutants
Authors: Amato F. , Viana M. , Richard A. , Furger M. , Prevot A. S. H. , Nava S. , Lucarelli F. , Querol X. , Alastuey A. , Reche C. , Moreno T. , Pandolfi M. , Pey J.
Published: January 2011

Abstract. Size and time-resolved roadside enrichments of atmospheric particulate pollutants in PM10 were detected and quantified in a Mediterranean urban environment (Barcelona, Spain). Simultaneous data from one urban background (UB), one traffic (T) and one heavy traffic (HT) location were analysed, and roadside PM10 enrichments (RE) in a number of elements arising from vehicular emissions were calculated. Tracers of primary traffic emissions (EC, Fe, Ba, Cu, Sb, Cr, Sn) showed the largest REs (>70%). Other traffic tracers (Zr, Cd) showed lower but still consistent REs (25–40%), similar to those obtained for mineral matter resulting from road dust resuspension (Ca, La, Ce, Ti, Ga, Sr, 30–40%). The sum of primary and secondary organic carbon showed a RE of 41%, with contributions of secondary OC (SOC) to total OC ranging from 46% at the HT site, 63% at the T site, and 78% in the UB. Finally, other trace elements (As, Co, Bi) showed unexpected but consistent roadside enrichments (23% up to 69%), suggesting a link to traffic emissions even though the emission process is unclear. Hourly-resolved PM speciation data proved to be a highly resourceful tool to determine the source origin of atmospheric pollutants in urban environments. At the HT site, up to 62% of fine Mn was attributable to industrial plumes, whereas coarse Mn levels were mainly attributed to traffic. Similarly, even though Zn showed on average no roadside enrichment and thus was classified as industrial, the hourly-resolved data proved that at least 15% of coarse Zn may be attributed to road traffic emissions. In addition, our results indicate that secondary nitrate formation occurs within the city-scale, even in the absence of long atmospheric residence times or long-range atmospheric transport processes.
In-cloud oxalate formation in the global troposphere: a 3-D modeling study
Authors: Myriokefalitakis S. , Tsigaridis K. , Mihalopoulos N. , Sciare J. , Nenes A. , Segers A. , Kanakidou M.
Published: January 2011

Abstract. Organic acids attract increasing attention as contributors to atmospheric acidity, secondary organic aerosol mass and aerosol hygroscopicity. Oxalic acid is globally the most abundant dicarboxylic acid, formed via chemical oxidation of gas-phase precursors in the aqueous phase of aerosols and droplets. Its lifecycle and atmospheric global distribution remain highly uncertain and are the focus of this study. The first global spatial and temporal distribution of oxalate, simulated using a state-of-the-art aqueous phase chemical scheme embedded within the global 3-dimensional chemistry/transport model TM4-ECPL, is here presented. The model accounts for comprehensive gas-phase chemistry and its coupling with major aerosol constituents (including secondary organic aerosol). Model results are consistent with ambient observations of oxalate at rural and remote locations (slope = 0.83 ± 0.06, r2 = 0.67, N = 106) and suggest that aqueous phase chemistry contributes significantly to the global atmospheric burden of secondary organic aerosol. In TM4-ECPL most oxalate is formed in-clouds and less than 10% is produced in aerosol water. About 61% of the oxalate is removed via wet deposition, 35% by in-cloud reaction with hydroxyl radical and 4% by dry deposition. The global oxalate net chemical production is calculated to be about 17–27 Tg yr−1 with almost 91% originating from biogenic hydrocarbons, mainly isoprene. This condensed phase net source of oxalate in conjunction with a global mean turnover time against deposition of about 5 days, maintain oxalate's global tropospheric burden of 0.24–0.39 Tg that is about 13–19% of calculated total organic aerosol burden.
The use of algorithms to predict surface seawater dimethyl sulphide concentrations in the SE Pacific, a region of steep gradients in primary productivity, biomass and mixed layer depth
Authors: Hind A. J. , Rauschenberg C. D. , Johnson J. E. , Yang M. , Matrai P. A.
Published: January 2011

Abstract. Dimethyl sulphide (DMS) is an important precursor of cloud condensation nuclei (CCN), particularly in the remote marine atmosphere. The SE Pacific is consistently covered with a persistent stratocumulus layer that increases the albedo over this large area. It is not certain whether the source of CCN to these clouds is natural and oceanic or anthropogenic and terrestrial. This unknown currently limits our ability to reliably model either the cloud behaviour or the oceanic heat budget of the region. In order to better constrain the marine source of CCN, it is necessary to have an improved understanding of the sea-air flux of DMS. Of the factors that govern the magnitude of this flux, the greatest unknown is the surface seawater DMS concentration. In the study area, there is a paucity of such data, although previous measurements suggest that the concentration can be substantially variable. In order to overcome such data scarcity, a number of climatologies and algorithms have been devised in the last decade to predict seawater DMS. Here we test some of these in the SE Pacific by comparing predictions with measurements of surface seawater made during the Vamos Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) in October and November of 2008. We conclude that none of the existing algorithms reproduce local variability in seawater DMS in this region very well. From these findings, we recommend the best algorithm choice for the SE Pacific and suggest lines of investigation for future work.
Microbiology and atmospheric processes: research challenges concerning the impact of airborne micro-organisms on the atmosphere and climate
Authors: Morris C. E. , Sands D. C. , Bardin M. , Jaenicke R. , Vogel B. , Leyronas C. , Ariya P. A. , Psenner R.
Published: January 2011

Abstract. For the past 200 years, the field of aerobiology has explored the abundance, diversity, survival and transport of micro-organisms in the atmosphere. Micro-organisms have been explored as passive and severely stressed riders of atmospheric transport systems. Recently, an interest in the active roles of these micro-organisms has emerged along with proposals that the atmosphere is a global biome for microbial metabolic activity and perhaps even multiplication. As part of a series of papers on the sources, distribution and roles in atmospheric processes of biological particles in the atmosphere, here we describe the pertinence of questions relating to the potential roles that air-borne micro-organisms might play in meteorological phenomena. For the upcoming era of research on the role of air-borne micro-organisms in meteorological phenomena, one important challenge is to go beyond descriptions of abundance of micro-organisms in the atmosphere toward an understanding of their dynamics in terms of both biological and physico-chemical properties and of the relevant transport processes at different scales. Another challenge is to develop this understanding under contexts pertinent to their potential role in processes related to atmospheric chemistry, the formation of clouds, precipitation and radiative forcing. This will require truly interdisciplinary approaches involving collaborators from the biological and physical sciences, from disciplines as disparate as agronomy, microbial genetics and atmosphere physics, for example.
Imprint of past and present environmental conditions on microbiology and biogeochemistry of coastal Quaternary sediments
Authors: Beck M. , Riedel T. , Graue J. , Köster J. , Kowalski N. , Wu C. S. , Wegener G. , Lipsewers Y. , Freund H. , Böttcher M. E. , Brumsack H.-J. , Cypionka H. , Rullkötter J. , Engelen B.
Published: January 2011

Abstract. To date, North Sea tidal-flat sediments have been intensively studied down to a depth of 5 m below seafloor (mbsf). However, little is known about the biogeochemistry, microbial abundance, and activity of sulfate reducers as well as methanogens in deeper layers. In this study, two 20 m-long cores were retrieved from the tidal-flat area of Spiekeroog Island, NW Germany. The drill sites were selected with a close distance of 900 m allowing to compare two depositional settings: first, a paleo-channel filled with Holocene sediments and second, a mainly Pleistocene sedimentary succession. Analyzing these cores, we wanted to test to which degree the paleo-environmental imprint is superimposed by present processes. In general, the numbers of bacterial 16S rRNA genes are one to two orders of magnitude higher than those of Archaea. The abundances of key genes for sulfate reduction and methanogenesis (dsrA and mcrA) correspond to the sulfate and methane profiles. A co-variance of these key genes at sulfate-methane interfaces and enhanced ex situ AOM rates suggest that anaerobic oxidation of methane may occur in these layers. Microbial and biogeochemical profiles are vertically stretched relative to 5 m-deep cores from shallower sediments in the same study area, but still appear compressed compared to deep sea sediments. Our interdisciplinary analysis shows that the microbial abundances and metabolic rates are elevated in the Holocene compared to Pleistocene sediments. However, this is mainly due to present environmental conditions such as pore water flow and organic matter availability. The paleo-environmental imprint is still visible but superimposed by these processes.
A coupled physical-biological model of the Northern Gulf of Mexico shelf: model description, validation and analysis of phytoplankton variability
Authors: Fennel K. , Hetland R. , Feng Y. , DiMarco S.
Published: January 2011

Abstract. The Texas-Louisiana shelf in the Northern Gulf of Mexico receives large inputs of nutrients and freshwater from the Mississippi/Atchafalaya River system. The nutrients stimulate high rates of primary production in the river plume, which contributes to the development of a large and recurring hypoxic area in summer. The mechanistic links between hypoxia and river discharge of freshwater and nutrients are complex as the accumulation and vertical export of organic matter, the establishment and maintenance of vertical stratification, and the microbial degradation of organic matter are controlled by a non-linear interplay of factors. We present results from a realistic, 3-dimensional, physical-biological model that includes the processes thought to be of first order importance to hypoxia formation and demonstrate that the model realistically reproduces many features of observed nitrate and phytoplankton dynamics including observed property distributions and rates. We then contrast the environmental factors and phytoplankton source and sink terms characteristic of three model subregions that represent an ecological gradient from eutrophic to oligotrophic conditions. We analyze specifically the reasons behind the counterintuitive observation that primary production in the light-limited plume region near the Mississippi River delta is positively correlated with river nutrient input. We find that, while primary production and phytoplankton biomass are positively correlated with nutrient load, phytoplankton growth rate is not. This suggests that accumulation of biomass in this region is not primarily controlled bottom up by nutrient-stimulation, but top down by systematic differences in the loss processes. We hypothesize that increased retention of river water in high discharge years explains this phenomenon.
Impact of CO2 and climate on the Last Glacial Maximum vegetation
Authors: Woillez M.-N. , Kageyama M. , Krinner G. , de Noblet-Ducoudré N. , Viovy N. , Mancip M.
Published: January 2011

Abstract. Vegetation reconstructions from pollen data for the Last Glacial Maximum (LGM), 21 kyr ago, reveal lanscapes radically different from the modern ones, with, in particular, a massive regression of forested areas in both hemispheres. Two main factors have to be taken into account to explain these changes in comparison to today's potential vegetation: a generally cooler and drier climate and a lower level of atmospheric CO2. In order to assess the relative impact of climate and atmospheric CO2 changes on the global vegetation, we simulate the potential modern vegetation and the glacial vegetation with the dynamical global vegetation model ORCHIDEE, driven by outputs from the IPSL_CM4_v1 atmosphere-ocean general circulation model, under modern or glacial CO2 levels for photosynthesis. ORCHIDEE correctly reproduces the broad features of the glacial vegetation. Our modelling results support the view that the physiological effect of glacial CO2 is a key factor to explain vegetation changes during glacial times. In our simulations, the low atmospheric CO2 is the only driver of the tropical forests regression, and explains half of the response of temperate and boreal forests to glacial conditions. Our study shows that the sensitivity to CO2 changes depends on the background climate over a region, and also depends on the vegetation type, needleleaf trees being much more sensitive than broadleaf trees in our model. This difference of sensitivity leads to a dominance of broadleaf types in the remaining simulated forests, which is not supported by pollen data, but nonetheless suggests a potential impact of CO2 on the glacial vegetation assemblages. It also modifies the competitivity between the trees and makes the amplitude of the response to CO2 dependent on the initial vegetation state.
Hydrological characterization of watersheds in the Blue Nile Basin, Ethiopia
Authors: Gebrehiwot S. G. , Ilstedt U. , Gärdenas A. I. , Bishop K.
Published: January 2011

Abstract. Thirty-two watersheds (31–4350 km2), in the Blue Nile Basin, Ethiopia, were hydrologically characterized with data from a study of water and land resources by the US Department of Interior, Bureau of Reclamation (USBR) published in 1964. The USBR document contains data on flow, topography, geology, soil type, and land use for the period 1959 to 1963. The aim of the study was to identify watershed variables best explaining the variation in the hydrological regime, with a special focus on low flows. Moreover, this study aimed to identify variables that may be susceptible to management policies for developing and securing water resources in dry periods. Principal Component Analysis (PCA) and Partial Least Square (PLS) were used to analyze the relationship between five hydrologic response variables (total flow, high flow, low flow, runoff coefficient, low flow index) and 30 potential explanatory watershed variables. The explanatory watershed variables were classified into three groups: land use, climate and topography as well as geology and soil type. Each of the three groups had almost equal influence on the variation in hydrologic variables (R2 values ranging from 0.3 to 0.4). Specific variables from within each of the three groups of explanatory variables were better in explaining the variation. Low flow and low flow index were positively correlated to land use types woodland, dense wet forest and savannah grassland, whereas grazing land and bush land were negatively correlated. We concluded that extra care for preserving low flow should be taken on tuffs/basalts which comprise 52% of the Blue Nile Basin. Land use management plans should recognize that woodland, dense wet forest and savannah grassland can promote higher low flows, while grazing land diminishes low flows.
An application of GLEAM to estimating global evaporation
Authors: Miralles D. G. , De Jeu R. A. M. , Gash J. H. , Holmes T. R. H. , Dolman A. J.
Published: January 2011

Abstract. A physics-based methodology is applied to estimate global land-surface evaporation from multi-satellite observations. GLEAM (Global Land-surface Evaporation: the Amsterdam Methodology) combines a wide range of remotely sensed observations within a Priestley and Taylor-based framework. Daily actual evaporation is derived at quarter degree resolution over the world's land surface. A running water balance of the vertical profile of soil moisture in the root zone is used to estimate the effect of soil water stress on transpiration. Forest rainfall interception, evaporation from bare soil, transpiration and snow sublimation are calculated independently. The inclusion of soil moisture deficit and forest rainfall interception – by means of the Gash analytical model – leads to an improved representation of the magnitude and distribution of the latent heat flux over semiarid and forested regions. Analyses of the global results show that interception loss plays an important role in the partition of the precipitation into evaporation and water available for runoff at a continental scale. The global distribution of evaporation and its different components is analysed to understand the relative magnitude of each component over different ecosystems. This study gives new insights into the relative importance of precipitation and net radiation in driving evaporation, and how the seasonal influence of these controls varies over the different regions of the world. Precipitation is recognised as an important factor driving evaporation, not only in areas that have limited soil water availability, but also in areas of high rainfall interception and low available energy.
Machine learning modelling for predicting soil liquefaction susceptibility
Authors: Samui P. , Sitharam T. G.
Published: January 2011

Abstract. This study describes two machine learning techniques applied to predict liquefaction susceptibility of soil based on the standard penetration test (SPT) data from the 1999 Chi-Chi, Taiwan earthquake. The first machine learning technique which uses Artificial Neural Network (ANN) based on multi-layer perceptions (MLP) that are trained with Levenberg-Marquardt backpropagation algorithm. The second machine learning technique uses the Support Vector machine (SVM) that is firmly based on the theory of statistical learning theory, uses classification technique. ANN and SVM have been developed to predict liquefaction susceptibility using corrected SPT [(N1)60] and cyclic stress ratio (CSR). Further, an attempt has been made to simplify the models, requiring only the two parameters [(N1)60 and peck ground acceleration (amax/g)], for the prediction of liquefaction susceptibility. The developed ANN and SVM models have also been applied to different case histories available globally. The paper also highlights the capability of the SVM over the ANN models.
Reflection seismic studies over the end-glacial Burträsk fault, Skellefteå, Sweden
Authors: Juhlin C. , Lund B.
Published: January 2011

Abstract. Reflection seismic data were acquired along a ca. 22 km long profile over the end-glacial Burträsk fault with a nominal receiver and source spacing of 20 m. A steeply dipping reflection can be correlated to the Burträsk fault, indicating that the fault dips at about 55° to the southeast near the surface. The reflection from the fault is rather poorly imaged, probably due to a lateral offset in the fault of about 1 km at this location and the crookedness of the seismic profile in the vicinity of the fault. A more pronounced steeply dipping reflection is observed about 4 km southeast of the Burträsk fault. Based on its correlation with a topographic low at the surface this reflection is interpreted to originate from a fracture zone. There are no signs of large displacements along this zone as the glacial ice receded, but earthquakes could be associated with it today. Other reflections on the processed seismic section may originate from changes in lithological variations in the supra-crustal rocks or from intrusions of more mafic rock. Constraints on the fault geometry provided by the reflection seismic data will help determine what stresses were required to activate the fault when the major rupture along it occurred ca. 9500 years ago.
Application of a minimal glacier model to Hansbreen, Svalbard
Authors: Oerlemans J. , Jania J. , Kolondra L.
Published: January 2011

Abstract. Hansbreen is a well studied tidewater glacier in the southwestern part of Svalbard, currently about 16 km long. Since the end of the 19th century it has been retreating over a distance of 2.7 km. In this paper the global dynamics of Hansbreen are studied with a minimal glacier model, in which the ice mechanics are strongly parameterised and a simple law for iceberg calving is used. The model is calibrated by reconstructing a climate history in such a way that observed and simulated glacier length match. In addition, the calving law is tuned to reproduce the observed mean calving flux for the period 2000–2008. Equilibrium states are studied for a wide range of values of the equilibrium line altitude. The dynamics of the glacier are strongly nonlinear. The height-mass balance feedback and the water depth-calving flux feedback give rise to cusp catastrophes in the system. For the present climatic conditions Hansbreen cannot survive. Depending on the imposed climate change scenario, in AD 2100 Hansbreen is predicted to have a length between 10 and 12 km. The corresponding decrease in ice volume (relative to the volume in AD 2000) is 45 to 65%. Finally the late-Holocene history of Hansbreen is considered. We quote evidence from dated peat samples that Hansbreen did not exist during the Holocene Climatic Optimum. We speculate that at the end of the mid-Holocene Climatic Optimum Hansbreen could advance because the glacier bed was at least 50 m higher than today, and because the tributary glaciers on the western side may have supplied a significant amount of mass to the main stream. The excavation of the overdeepening and the formation of the shoal at the glacier terminus probably took place during the Little Ice Age.
Intravitreal Anti-VEGF Bevacizumab (Avastin) for External Beam-Related Radiation Retinopathy
Authors: Finger Paul T. , Mukkamala Sri Krishna
Published: January 2011

Purpose

TO report on intravitreal bevacizumab treatment for external beam radiation therapy (EBRT)-related radiation maculopathy.

Methods

Three patients (4 eyes) with EBRT-related maculopathy were treated with periodic (4- to 8-week) intravitreal injections of bevacizumab (1.25 mg in 0.05 cc). Outcome measures included best-corrected Early Treatment Diabetic Retinopathy Study visual acuity, retinal examination, fundus photography, fluorescein angiography, and optical coherence tomography.

Results

Patients were diagnosed with Stage 3 radiation maculopathy occurring 12, 19, and 48 months after irradiation. One received 50 Gy of 6-MV photon EBRT for a maxillary carcinoma, the second 30.6 Gy of 6-MV photon EBRT for intraocular lymphoma, and the third 72 Gy proton beam irradiation for adenoid cystic carcinoma of the lacrimal gland. With up to 33 months follow-up, visual acuities improved (8 and 11 letters) in 2 eyes, gained 5 letters in 1 eye and 1 decreased 5 letters from 20/16 to 20/20. All cases demonstrated clinical findings of decreased intraretinal hemorrhages, cotton-wool spots, and retinal edema. There were no significant ocular or systemic side effects.

Conclusions

Intravitreal anti-VEGF therapy was associated with reductions of EBRT-related retinopathy. No ocular or systemic side effects were noted. Anti-VEGF therapy may be considered radiation maculopathy secondary to EBRT.
Chronic exposure to violent video games is not associated with alterations of emotional memory
Authors: Bowen Holly J. , Spaniol Julia
Published: January 2011

Although acute effects of violent video game (VVG) exposure on affect and behaviour have been studied extensively, less is known about VVG effects on cognition. The present study examined whether chronic exposure to VVGs was associated with alterations in emotional long‐term memory. Participants completed an old‐new recognition task with 300 pictures of scenes ranging in emotion (negative, neutral and positive). We analysed accuracy and reaction time data using diffusion modelling to test a desensitization hypothesis. According to this hypothesis, VVG players would show reduced memory or a less liberal response bias for negative stimuli, compared with nonplayers. Contrary to the desensitization hypothesis, VVG exposure was not associated with differences in memory or response bias. This result suggests that, unlike other cognitive domains, long‐term memory may be robust to deleterious influences of chronic VVG exposure. Copyright © 2010 John Wiley & Sons, Ltd.
Macro‐ and Nanomechanical Properties and Strain Rate Sensitivity of Accumulative Roll Bonded and Equal Channel Angular Pressed Ultrafine‐Grained Materials
Authors: Böhner Andreas , Maier Verena , Durst Karsten , Höppel Heinz Werner , Göken Mathias
Published: January 2011

Several processes of severe plastic deformation are suitable for the production of materials with ultrafine‐grained microstructures which are known to exhibit high strength and often good ductility as well as strain rate sensitive behavior. The most promising ones are equal channel angular pressing (ECAP) for bulk material and accumulative roll bonding (ARB) for the production of sheet material. In order to evaluate the influence of the process on these mechanical properties and the strain rate sensitivity, tensile tests, and nanoindentation tests were performed on material produced up to similar effective plastic strains of εARB = 6.4 and εECAP = 6.3. It could be shown that the macroscopic strength is slightly higher for ARB than for ECAP material and vice versa in nanoindentation. Independent of the testing method, the strain rate sensitivities and activation volumes are similar for both materials. Thus, both processes performed up to similar effective plastic strains lead to comparable improvements in the mechanical properties. Additionally it could be shown, that this comparison allows the identification of the dominant deformation mechanism which is responsible for the observed strain rate sensitivity.
On the multi‐orbital band structure and itinerant magnetism of iron‐based superconductors
Authors: Andersen O.K. , Boeri L.
Published: January 2011

This paper explains the multi‐orbital band structures and itinerant magnetism of the iron‐pnictide and chalcogenide superconductors. We first describe the generic band structure of a single, isolated FeAs layer. Use of its Abelian glide‐mirror group allows us to reduce the primitive cell to one FeAs unit. For the lines and points of high symmetry in the corresponding large, square Brillouin zone, we specify how the one‐electron Hamiltonian factorizes. From density‐functional theory, and for the observed structure of LaOFeAs, we generate the set of eight Fe d and As p localized Wannier functions and their tight‐binding (TB) Hamiltonian, h (k) . For comparison, we generate the set of five Fe d Wannier orbitals. The topology of the bands, i. e. allowed and avoided crossings, specifically the origin of the d6 pseudogap, is discussed, and the role of the As p orbitals and the elongation of the FeAs4 tetrahedron emphasized. We then couple the layers, mainly via interlayer hopping between As pz orbitals, and give the formalism for simple tetragonal and body‐centered tetragonal (bct) stackings. This allows us to explain the material‐specific 3D band structures, in particular the complicated ones of bct BaFe2As2 and CaFe2As2 whose interlayer hoppings are large. Due to the high symmetry, several level inversions take place as functions of kz or pressure, and linear band dispersions (Dirac cones) are found at many places. The underlying symmetry elements are, however, easily broken by phonons or impurities, for instance, so that the Dirac points are not protected. Nor are they pinned to the Fermi level because the Fermi surface has several sheets. From the paramagnetic TB Hamiltonian, we form the band structures for spin spirals with wavevector q by coupling h (k) and h (k + q). The band structure for stripe order is studied in detail as a function of the exchange potential, Δ, or moment, m, using Stoner theory. Gapping of the Fermi surface (FS) for small Δ requires matching of FS dimensions (nesting) and d‐orbital characters. The interplay between pd hybridization and magnetism is discussed using simple 4 × 4 Hamiltonians. The origin of the propeller‐shaped Fermi surface is explained in detail. Finally, we express the magnetic energy as the sum over band‐structure energies and this enables us to understand to what extent the magnetic energies might be described by a Heisenberg Hamiltonian, and to address the much discussed interplay between the magnetic moment and the elongation of the FeAs4 tetrahedron.
Influence of fluorinated segments of variable length on the thickening properties of a model HASE skeleton
Authors: Oddes Olivier , Amigoni Sonia , Taffin de Givenchy Elisabeth , Reeve Paul , Duccini Yves , Guittard Frédéric
Published: January 2011

Introduction of fluorocarbon segments in an associative thickener copolymer (ethyl acrylate (EA)/methacrylic acid/macromonomer) was achieved by the substitution of EA with either trifluoroethyl acrylate, 2‐perfluorobutylethyl acrylate, or 2‐perfluorooctylethyl acrylate. The thickening properties were evaluated by rheological flow experiments in aqueous medium as well as in 10 wt % of sodium dodecyl sulfate (SDS) aqueous solution. Whereas in the literature no particular attention is devoted to the impact of the ethylene moieties in hydrophobically modified alkali‐soluble emulsion (HASE) skeleton, our study reveals they contribute significantly to the performances when modified by an incompatible fluorocarbon segment. Moreover, the synthesis process has a huge influence by inducing a specific distribution of the fluorinated acrylates in the macromolecule. The amount of substitution is also important and even 20 mol % of EA substituted reveals a great impact on the rheological properties of the copolymer solutions. Whereas an SDS aqueous medium generally destroys almost all the hydrocarbon interactions from the macromonomer, the total replacement of ethyl groups by trifluoroethyl groups with a cosolvent process, leads to emulsions with an equivalent thickening effect than the reference hydrocarbon HASE used. This result is quite encouraging for research work on the synthesis of HASE with increased biocompatibility. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Dissection videos do not improve anatomy examination scores
Authors: Mahmud Waqas , Hyder Omar , Butt Jamaal , Aftab Arsalan
Published: January 2011

In this quasi‐experimental study, we describe the effect of showing dissection videos on first‐year medical students' performance in terms of test scores during a gross anatomy course. We also surveyed students' perception regarding the showing of dissection videos. Two hundred eighty‐seven first‐year medical students at Rawalpindi Medical College in Pakistan, divided into two groups, dissected one limb in first term and switched over to the other limb in the second term. During the second term, instruction was supplemented by dissection videos. Second‐term anatomy examination marks were compared with first‐term scores and with results from first‐year medical students in previous years. Multiple linear regression analysis was performed, with term scores (continuous, 0–200) as the dependent variable. Students shown dissection videos scored 1.26 marks higher than those not shown. The relationship was not statistically significant (95% CI: −1.11, 3.70; P = 0.314). Ninety‐three percent of students favored regular inclusion of dissection videos in curriculum, and 50% termed it the best source for learning gross anatomy. Seventy‐six percent of students did not perform regular cadaver dissection. The most frequent reason cited for not performing regular dissection was high student‐cadaver ratio. Dissection videos did not improve performance on final examination scores; however, students favored their use. Anat Sci Educ. © 2011 American Association of Anatomists.
Bemessung von Stahlbetonstützen im Brandfall: Absicherung der nicht‐linearen Zonenmethode durch Laborversuche
Authors: Cyllok Michael , Achenbach Marcus
Published: January 2011

Die nicht‐lineare Zonenmethode kann für die Bemessung von Stahlbetonstützen im Brandfall verwendet werden. Sie bildet die wesentlichen mechanischen Auswirkungen einer Brandbeanspruchung ab und wurde durch einen Ergebnisvergleich nachgewiesen. Hierzu wurden Traglasten und Verformungskurven sowohl mit der nicht‐linearen Zonenmethode als auch mit den Allgemeinen Rechenverfahren bestimmt und beurteilt.

In Ergänzung dieses Nachweises wird im vorliegenden Beitrag statistisch untersucht, ob eine Nachrechnung von Laborversuchen mit der nicht‐linearen Zonenmethode eine ausreichende Sicherheit nach DIN 4102‐2 erreicht.

Die vorliegenden Laborversuche werden hierzu mit ihren Systemparametern dargestellt. Nicht genau bekannte Randbedingungen werden durch begründete Annahmen vervollständigt. Besonderheiten der Nachrechnung der Laborversuche mit der nicht‐linearen Zonenmethode werden beleuchtet. Die statistische Auswertung dieser Nachrechnung zeigt die relevanten Kennzahlen, mit denen im Ergebnis eine ausreichende Sicherheit nach DIN 4102‐2 nachgewiesen werden kann.

Design of Reinforced Concrete Columns exposed to Fire: Validation of Simplified Method (Zone Method) by Tests

The nonlinear zone method (simplified calculation method) can be used for design of reinforced concrete columns exposed to fire. The decisive action effects of a fire exposure on the structural behaviour are considered by this method and have been proofed by a comparison of ultimate loads and deformation curves computed by using nonlinear zone method as well as using advanced method.

In addition, this article statistically evaluates how safe – according to DIN 4102‐2 – published full scale tests can be modelled by using nonlinear zone method.

Information to mentioned tests is shown. Reasonable assumptions are given for not published boundary conditions. The application of nonlinear zone method is explained. The statistical evaluation leads to governing key data, which proof adequate safety according to DIN 4102‐2.
Use of postmortem human subjects to describe injury responses and tolerances
Authors: Yoganandan Narayan , Stemper Brian D. , Pintar Frank A. , Maiman Dennis J.
Published: January 2011

Traumatic injuries from blunt, penetrating, and blast events expose the human body to unintentional and intentional external mechanical loads. To mitigate trauma and develop safety‐engineered devices for clinical and bioengineering applications, it is critical to delineate the structural load‐bearing anatomy and biomechanics of the various components of the human body. This article presents advances made in the understanding of the injury responses and tolerances through experiments conducted using intact or segmented tissues from postmortem human subjects (PMHS), and a considerable majority of data for the presentation has been extracted from studies conducted at the Institutions of the authors. The role of the PMHS model for studying traumatic injuries to the head and face, vertebral column (cervical, thoracic and lumbar spines), thorax, abdomen, pelvis, and lower extremities is discussed. Different impact loading scenarios, likely responsible for the initial trauma causation, are considered in the analysis and determination of the human response to injury. Clinical advances made using the PMHS model are discussed. This includes vertebral stabilization system evaluations secondary to traumatic injuries to the spinal column. The critical importance of using data from the PMHS model in developing validated computational models for advancing crashworthiness research, occupant safety in motor vehicle crashes, medical devices, and safety‐engineering applications is highlighted. Clin. Anat. 24:282–293, 2011. © 2011 Wiley‐Liss, Inc.
The use of plastinated prosections for teaching anatomy—The view of medical students on the value of this learning resource
Authors: Fruhstorfer B.H. , Palmer J. , Brydges S. , Abrahams P.H.
Published: January 2011

Over the past decade, the role of anatomical teaching in the undergraduate medical curriculum has changed considerably. At some medical schools, active dissection of cadaveric specimens is gradually being replaced by prosection‐based methods and other resources such as e‐learning. Warwick Medical School has recently obtained a large collection of plastinated prosections, which replace wet cadaveric specimens in undergraduate anatomy teaching. The aim of this study was to examine students' views on the use of plastinated prosections for their anatomical learning. A mixed method approach was employed using a questionnaire and focus group for data collection. The questionnaire was completed by 125 first‐year medical students (response rate 68%). The majority of students (94%) rated plastinated prosections as a valuable resource for their anatomical learning. Various features of the specimens were highlighted, such as the detailed view of relevant anatomy, appreciation of relations between structures, and visualization of anatomy in real life. However, learning on plastinated prosections was perceived to be compromised because of limitations in terms of tactile and emotional experience. We conclude that plastinated prosections are an adequate resource for the early stages of undergraduate training, but that the learning experience may be further enhanced by providing opportunity for the study of wet cadaveric material. Clin. Anat. 24:246–252, 2011. © 2011 Wiley‐Liss, Inc.
Ankle injury mechanisms: Lessons learned from cadaveric studies
Authors: Funk James R.
Published: January 2011

The biomechanics of ankle injury have been studied extensively, primarily through mechanical testing of human cadavers. Cadaveric testing is an invaluable methodology in biomechanics, because the magnitude and direction of the loading can be measured precisely and correlated with the resulting injury pattern. Clinical and epidemiological studies provide useful descriptions of injury patterns that occur in the real world, but their retrospective nature precludes a definitive analysis of the forces that caused the injury. Understanding the mechanism of ankle injuries is essential for developing countermeasures to prevent injury and for reconstructing injurious events. Knowledge of an injury's mechanism can also suggest potential associated injuries, which is helpful in diagnosis and treatment. The purpose of this review is to summarize the published research on ankle injury mechanisms with an emphasis on biomechanical experiments on human cadavers. Injury patterns are described based on the principal axis of force or torque producing the injury in conjunction with off‐axis forces and out‐of‐plane foot positions. A mechanistic description of ankle injuries is complicated by the fact that the same mechanism can sometimes produce different injuries and the same injury can sometimes be caused by multiple mechanisms. Nonetheless, a framework for relating injury mechanisms and injury patterns is a valuable tool in the understanding, prevention, and treatment of ankle injuries. Clin. Anat. 24:350–261, 2011. © 2011 Wiley‐Liss, Inc.
Decolorization of Textile Azo‐metal Complex Dyes by a Halophilic Bacterium Isolated from Çamaltı Saltern in Turkey
Authors: Demirci Armağan , Mutlu Mehmet Burçin , Güven Alaettin , Korcan Elif , Güven Kıymet
Published: January 2011

The decolorization of some of azo‐metal complex dyes used in textile industry was investigated in this study. The halophilic prokaryotes isolated from a solar sea‐saltern (Çamaltı) in Turkey were screened for resistance to five commercial azo and mixture of azo‐metal complex dyes. Only one bacterium was found to be resistant against two of dyes, namely Lanaset Navy R and Lanaset Brown B. The bacterium was identified as Halobacillus sp. C‐22 according to 16S rRNA gene sequence analyses. Decolorization experiments were carried out at 120 mg/L concentration of both dyes, at room temperature, and with an acidic pH of 4.5. Lanaset Brown B was decolorized at a high adsorbance ratio (96.12%) at the 78th hour. However, Lanaset Navy R was rapidly decolorized in 10 min (46.67%) and showed the highest adsorbance ratio (60.66%) at the third hour. Freundlich and Langmuir equilibrium isotherm models were used to evaluate the adsorption of dyes and Freundlich isoterm was more suitable for biosorpsiyon of both azo dyes. The functional groups on Halobacillus sp. C‐22 for decolorization were characterized by FT‐IR. This is the first study to reveal potential of Halobacillus sp. for decolorization of textile azo‐metal complex dyes.
Spectrophotometric Determination of Cationic Surfactants Based on Their Effect on the Complexes of Chrome Azurol S with Be2+ and Al3+ Cations
Authors: Afkhami Abbas , Nematollahi Davood , Madrakian Tayyebeh , Hajihadi Mitra
Published: January 2011

Simple, rapid, and sensitive spectrophotometric methods have been proposed for the determination of cationic surfactants (CS) as cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium (DTAB), and cetylpyridinium bromide (CPB). The methods are based on the effects of CSs on the complexes of Al3+ and Be2+ with Chrome Azurol S (CAS). The optimum reaction conditions such as CAS concentration, metal ion concentration, and pH have been studied and found to be 2.0 × 10−4 mol L−1 CAS, 0.5 mg L−1 Al3+ or 0.4 mg L−1 Be2+ and pH 5.4. The analytical characteristics of the methods such as limit of detections, limit of quantifications, and linear ranges have been obtained. CTAB, CPB, and DTAB could be determined by the Al–CAS complex in the ranges of 0.50–40.00, 0.20–10.00, and 0.40–10.00 µmol L−1, and for the Be–CAS complex in the ranges of 0.08–5.00, 0.08–3.00, and 0.20–6.00 µmol L−1, respectively. The limit of the detections of the method for the determination of CTAB, CPB, and DTAB for the Be–CAS complex has been found as 0.025, 0.024, and 0.061 µmol L−1, respectively. The interfering effect of some anions and cations was also tested. The method was applied to the determination of CS CTAB in conditioner shampoo and water samples.
High resolution three‐dimensional imaging: Evidence for cell cycle reentry in regenerating skeletal muscle
Authors: Calve Sarah , Simon Hans‐Georg
Published: January 2011

Newts and other urodele amphibians can replace lost structures including limbs, providing a vertebrate model for the study of regeneration of complex tissues. The composite of different cell and tissue types in the limb, however, presents a challenge for their imaging in three‐dimensions (3D) at cellular level resolution. To observe myofibers in vivo without distortion, we developed a streamlined protocol whereby 80 μm thick cryosections are mounted on slides, processed for immunohistochemistry, imaged using confocal microscopy and z‐stacks rendered in 3D. This methodology enabled precise in situ rendering of regenerating muscle, demonstrating cell cycle reentry of nuclei within the myofiber syncytium. The high resolution imaging of muscle or comparable tissue types as intact 3D entities in the context of extracellular and intracellular molecules allows for the determination of signaling and cell response pathways, making this method useful for studies that attempt to characterize rare physiological events in vivo. Developmental Dynamics 240:1233–1239, 2011. © 2011 Wiley‐Liss, Inc.
Interferon‐α induces unabated production of short‐lived plasma cells in pre‐autoimmune lupus‐prone (NZB×NZW)F1 mice but not in BALB/c mice
Authors: Mathian Alexis , Gallegos Mike , Pascual Virginia , Banchereau Jacques , Koutouzov Sophie
Published: January 2011

IFN‐α is known to play a critical role in the pathogenesis of systemic lupus erythematosus (SLE), but the mechanisms remain unclear. We previously showed that within weeks, exposure to IFN‐α in vivo induces lupus in pre‐autoimmune lupus‐prone NZB×NZW F1 (NZB/W) but not in BALB/c mice. In the current study, we show that in vivo expression of IFN‐α induces sustained B‐cell proliferation in both BALB/c and NZB/W mice. In NZB/W but not BALB/c mice, B‐cell proliferation was accompanied by a rapid and unabated production of autoantibody‐secreting cells (ASCs) in secondary lymphoid organs, suggesting that a B‐cell checkpoint is altered in the autoimmune background. The majority (>95%) of ASCs elicited in IFN‐α‐treated NZB/W mice were short‐lived and occurred without the induction of long‐lived plasma cells. A short course of cyclophosphamide caused a sharp drop in IFN‐α‐elicited short‐lived plasma cells, but the levels recovered within days following termination of treatment. Thus, our work provides new insights into effectiveness and limitations of the current SLE therapies.
Tolerance induction towards cardiac allografts under costimulation blockade is impaired in CCR7‐deficient animals but can be restored by adoptive transfer of syngeneic plasmacytoid dendritic cells
Authors: Liu Xiaosun , Mishra Pooja , Yu Songfeng , Beckmann Jan , Wendland Meike , Kocks Jessica , Seth Sebastian , Hoffmann Katharina , Hoffmann Matthias , Kremmer Elisabeth , Förster Reinhold , Worbs Tim
Published: January 2011

Deficiency of transplant recipients for the chemokine receptor CCR7 was originally described to slightly increase the survival time of vascularized solid organ grafts, probably due to a reduced priming of alloreactive T cells. Using a model of allotolerance induction by donor‐specific splenocyte transfusion (DST) in combination with anti‐CD40L mAb‐mediated costimulation blockade (CSB), we show here a striking failure of CCR7‐deficient (CCR7−/−) recipients to tolerate cardiac allografts. Furthermore, in addition to the recently described lack of Treg, CCR7−/− mice were found to harbor significantly reduced numbers of plasmacytoid dendritic cells (pDCs) within peripheral as well as mesenteric lymph nodes (LNs), but not the bone marrow or spleen. pDCs had previously been suggested to function as tolerogenic APC during allograft transplantation, and a single transfer of syngeneic WT pDCs, but not conventional DCs, was indeed sufficient to rescue graft survival in DST+CSB‐treated CCR7−/− recipients in a dose‐dependent manner. We therefore conclude that the nearly complete absence of pDCs within LNs of CCR7−/− mice prevents the successful induction of DST+CSB‐mediated allotolerance, leading to the observed acute rejection of cardiac allografts under tolerizing conditions.
Characterization of the immunoregulatory function of human TCR‐αβ+ CD4−CD8− double‐negative T cells
Authors: Voelkl Simon , Gary Regina , Mackensen Andreas
Published: January 2011

Regulatory T cells (Tregs) play an important role in the maintenance of immune tolerance to self‐antigens and are involved in modulating immune responses in autoimmunity, transplant rejection, and tumor immunity. Recently, a novel subset of TCR‐αβ+ CD4−CD8− (double negative, DN) T cells has been described to specifically suppress T‐cell responses in mice. Here, we demonstrate that human DN T cells are highly potent suppressors of both CD4+ and CD8+ T‐cell responses. In contrast to naturally occurring CD4+CD25+ Tregs, DN T cells have to be activated by antigen‐presenting cells (APCs) to induce their regulatory potential. The suppressive activity of DN T cells is neither mediated indirectly by modulation of APCs nor by competition for T‐cell growth factors. Furthermore, DN T‐cell‐mediated suppression toward responder T cells is TCR dependent and requires novel protein synthesis. In contrast to murine DN T cells, which eliminate effector T cells via Fas/FasL or perforin/granzyme, human DN T cells suppress proliferation of responder T cells by cell contact‐dependent mechanisms. Taken together, our data indicate that human DN T cells exert strong immunosuppressive effects on both CD4+ and CD8+ T cells and may serve as a new therapeutic approach to treat autoimmunity and transplant rejection.