bluuebunny/crossref_metadata_2025 huggingface dataset:
An Integrated Interactive-Spaced Education Radiology Curriculum for Preclinical Students
Authors: Tshibwabwa Eli , Mallin Robert , Fraser Madeleine , Tshibwabwa Martin , Sanii Reza , Rice James , Cannon Jenifer
Published: May 2017

Introduction:

The objective of this study is to determine whether a radiology module, together with online spaced education, helps students of an integrated problem-based learning (PBL) curriculum increase their radiology knowledge and long-term retention.

Materials and Methods:

Second-year students at the American University of Antigua College of Medicine participated in small groups of ten students each into two 2 h of radiology laboratories. The study comprised two cohorts: winter and fall 2013 students (control group) and 2014 students (experimental group). Both groups used face-to-face PBL. The students of the experimental group received additional online-spaced education. The skills were assessed for both groups before the beginning of laboratories and 4 weeks and 7 months after laboratories.

Results:

There was no significant difference on pretest between the control and experimental groups. On completion of the radiology laboratories, comparison of test results before and after training showed net improvement for both groups. The corresponding difference for the experimental group was higher compared to the one for the control group (7.83 vs. 6.21,P< 0.001). The difference between the scores on delayed test and pretest showed that the students of both groups demonstrated average knowledge improvement even though their level of performance was slightly below the posttest. The corresponding difference for the experimental group did not differ much from the posttest (P> 0.05), and no significant difference of scores was observed 7 months later for either group. Further, a higher percentage of the students in the experimental group strongly agreed that their learning objectives were met (92% vs. 71%,P> 0.001), and this trend persisted throughout the study.

Conclusion:

Online spaced education combined to a face-to-face PBL enhances not only the student's knowledge of basic radiology along with his/her self-assessment skills but also the long-term retention of radiology material and satisfaction with the integrated interactive system-based module. Future research is needed to see if medical students in need of additional education support may benefit from spaced education in the field of remediation.
Plane algebraic curves of arbitrary genus via Heegaard Floer homology
Authors: Borodzik Maciej , Hedden Matthew , Livingston Charles
Published: May 2017

Suppose

C

is a singular curve in

\mathbb CP^2

and it is topologically an embedded surface of genus

g

; such curves are called cuspidal. The singularities of

C

are cones on knots

K_i

. We apply Heegaard Floer theory to find new constraints on the sets of knots

\{K_i\}

that can arise as the links of singularities of cuspidal curves. We combine algebro-geometric constraints with ours to solve the existence problem for curves with genus one,

d > 33

, that possess exactly one singularity which has exactly one Puiseux pair

(p;q)

. The realized triples

(p,d,q)

are expressed as successive even terms in the Fibonacci sequence.
Cutting out arithmetic Teichmüller curves in genus two via Theta functions
Authors: Kappes André , Möller Martin
Published: May 2017

We compute the class of arithmetic genus two Teichmüller curves in the Picard group of pseudo-Hilbert modular surfaces, distinguished according to their torsion order and spin invariant. As an application, we compute the number of genus two square-tiled surfaces with these invariants.

The main technical tool is the computation of divisor classes of Hilbert Jacobi forms on the universal abelian surface over the pseudo-Hilbert modular surface.
Vanishing of cohomology with coefficients in representations on Banach spaces of groups acting on buildings
Authors: Oppenheim Izhar
Published: May 2017

We prove vanishing of cohomology with coefficients in representations on a large class of Banach spaces for a group acting “nicely” on a simplicial complexes based on spectral properties of the 1-dimensional links of the simplicial complex.
Classical solutions and higher regularity for nonlinear fractional diffusion equations
Authors: Vázquez Juan Luis , de Pablo Arturo , Quirós Fernando , Rodríguez Ana
Published: May 2017

We study the regularity properties of the solutions to the nonlinear equation with fractional diffusion

\partial_tu+(-\Delta)^{\sigma/2}\varphi(u)=0,

posed for

x\in \mathbb{R}^N

,

t>0

, with

0<\sigma<2

,

N\ge1

. If the nonlinearity satisfies some not very restrictive conditions:

\varphi\in C^{1,\gamma}(\mathbb{R})

,

1+\gamma>\sigma

, and

\varphi'(u)>0

for every

u\in\mathbb{R}

, we prove that bounded weak solutions are classical solutions for all positive times. We also explore sufficient conditions on the non-linearity to obtain higher regularity for the solutions, even

C^\infty

regularity. Degenerate and singular cases, including the power nonlinearity

\varphi(u)=|u|^{m-1}u

,

m>0

, are also considered, and the existence of positive classical solutions until the possible extinction time if

m < \frac{N-\sigma}{N}, N > \sigma

, and for all times otherwise, is proved.
The classification of Nichols algebras over groups with finite root system of rank two
Authors: Heckenberger István , Vendramin Leandro
Published: May 2017

We classify all groups

G

and all pairs

(V,W)

of absolutely simple Yetter–Drinfeld modules over

G

such that the support of

V\oplus W

generates

G

,

c_{W,V}c_{V,W}\ne\mathrm {id}

, and the Nichols algebra of the direct sum of

V

and

W

admits a finite root system. As a byproduct, we determine the dimensions of such Nichols algebras, and several new families of finite-dimensional Nichols algebras are obtained. Our main tool is the Weyl groupoid of pairs of absolutely simple Yetter–Drinfeld modules over groups.
Higher genus quasimap wall-crossing for semipositive targets
Authors: Ciocan-Fontanine Ionuţ , Kim Bumsig
Published: May 2017

In previous work we have conjectured wall-crossing formulas for genus zero quasimap invariants of GIT quotients and proved them via localization in many cases. We extend these formulas to higher genus when the target is semipositive, and prove them for semipositive toric varieties, in particular for toric local Calabi–Yau targets. The proof also applies to local Calabi–Yau's associated to some nonabelian quotients.
Hilbert's Tenth Problem over function fields of positive characteristic not containing the algebraic closure of a finite field
Authors: Eisenträger Kirsten , Shlapentokh Alexandra
Published: May 2017

We prove that the existential theory of any function field

K

of characteristic

p > 0

is undecidable in the language of rings augmented by constant symbols for the elements of a suitable recursive subfield, provided that the constant field does not contain the algebraic closure of a finite field. This theorem is the natural generalization of a theorem of Kim and Roush from 1992. We also extend our previous undecidability proof for function fields of higher transcendence degree to characteristic 2 and show that the first-order theory of
any
function field of positive characteristic is undecidable in the language of rings without parameters.
Reconstrucción virtual paleotopográfixca de la ciudad histórica de Cartagena (España)
Authors: Garcia-León Josefina , Ros-Sala María Milagrosa , García Martín Antonio , Torres Picazo Manuel , Cerezo Andreo Felipe , Ramallo Asensio Sebastián F.
Published: May 2017

The city of Cartagena and its immediate surroundings have experienced significant topographical changes throughout its history. Originally built on five hills which border south and west with the Mediterranean Sea, the city has expanded to the north over the last five decades, occupying a lacustrine system which has now dried up due to the diversion of riverbeds which, from time to time, used to flood the place. These changes have been documented and studied from the lithology present in over 400 geotechnical drillings carried out in the urban renewal of the city for the last two decades. In addition, another 20 new continuous drillings have been conducted within the Project “Surveying and planning a privileged Mediterranean city, Arqueotopos I and II” which is still ongoing. The information obtained is completed with the study of all existing historical maps on it. Digital Terrain Models (DTMs) have been generated with this drilling data, then several lithological layers have been selected for its interest: anthropic fill, mud and underlying bedrock. The thickness of each of the layers has been studied in different areas and viewed through various longitudinal profiles that have been plotted. Finally, a three-dimensional (3D) virtual reconstruction has been undertaken to see graphically the documented changes that have occurred in each of these layers, to serve both research and divulgation knowledge.
Authenticity through VR-based documentation of cultural heritage. A theoretical approach based on conservation and documentation practices
Authors: Muñoz Morcillo Jesús , Schaaf Franziska , Schneider Ralf H. , Robertson-von Trotha Caroline Y.
Published: May 2017

The visualization of 3D reconstructed artifacts often requires significant computing resources. The implementation of an object in  a  virtual  reality  (VR)  application  even necessitates the  reduction  of  the polygonal  mesh.  Consequently,  the communication and dissemination of “authentic” 3D reconstructions via immersive VR technologies has been a nearly impossible  feat for  many  researchers. However,  is the  issue really  computing resources,  or is it rather  the notion  of authenticity in an “auratic” sense, i.e., an excessive focus on physical evidence and survey data? In the present paper, we will discuss the authenticity requirements for virtual archaeology as set by the Seville Principles(2011), and we will analyse some limitations related to the current approaches. Furthermore, we will propose a pluralistic notion based on the contextualization of 3D objects in VR environments with synesthetic (i.e. multisensory) information. This new notion of authenticity  relies  on  conservation meanings rather than  physical  features.  In line  with  this  approach,  two  case studies will be commented: the multimodal 3D-documentation of the Jupiter Column(2AD) in Ladenburg, and the VR-based  re-enactment of  a  modern  work  of  art,  the  audio-kinetic  sculpture Kaleidophonic  Dog(1967)  by  Stephan  von Huene. These two projects provide valuable data for a revision of the notion of authenticity in both virtual archaeology and art conservation.
Creación de implantes 3D en procesos de conservación y restauración de vidrio arqueológico
Authors: Díaz-Marín Carmen , Aura-Castro Elvira
Published: May 2017

This article describes the restoration of a glass bowl from the 16th-17thcentury by creating its three-dimensional (3D)model. The final purpose is to work with this model in order to avoid damaging situations that are associated with the manipulation of fragile objects. The gap areas, those corresponding to the missing fragments not found in the excavation, were carried out by constructing digital implants. A restricted area of the 3D model has been duplicated in order to accommodate it to confined intervals of the gap. The final implants were printed with acrylonitrile butadiene styrene (ABS) filament. These implants replace the lost areas and give stability back to the item by recovering the original morphology. The result can be compared with the outcome obtained by a traditional process, but differs due to the fact that requires minimum manipulation of the item, so it can contribute to preserve and safeguard the restored object. This is a non-invasive method which is offered as an alternative treatment, where the archaeological object is replaced by its virtual model in the steps of the process after 3D data acquisition. Significant differences have not been found in the 3D printing results obtained with the two types of filaments tested (white and clear).
Phenomenological classification of cultural heritage: role of virtual reality
Authors: Lee Hyuk-Jin
Published: May 2017

Human consciousness is always the consciousness toward some thing and our perception of cultural heritage is no exception. Thus, understanding human cognition is closely related to understanding how the perceptible objects are classified in human mind. The perceptible objects include both physical and virtual experiences and thoughts, and it is important and necessary to analyze the types and the effective levels of those objects. With the emergence of Virtual Reality (VR) technologies in cultural heritage field, it is necessary to understand how and why different cognitive media such as realor visual reality including VR, are differently recognized by people. This study suggests the philosophical and theoretical frame for the usage of phenomenological classfication and analysis. By using this new classification with the case of Korean built heritage, the role of VR is explained in cultural discourse of the community.
3D mass digitization: a milestone for archeological documentation
Authors: Santos Pedro , Ritz Martin , Fuhrmann Constanze , Fellner Dieter
Published: May 2017

In the heritage field, the demand for fast and efficient 3D digitization technologies for historic remains is increasing. Besides, 3D digitization has proved to be a promising approach to enable precise reconstructions of objects. Yet, unlike the digital acquisition of cultural goods in 2D widely used today, 3D digitization often still requires a significant investment of time and money. To make it more widely available to heritage institutions, the Competence Center for Cultural Heritage Digitization at the Fraunhofer Institute for Computer Graphics Research IGD has developed CultLab3D, the world’s first 3D mass digitization facility for collections of three-dimensional objects. CultLab3D is specifically designed to automate the entire 3D digitization process thus allowing to scan and archive objects on a large-scale. Moreover, scanning and lighting technologies are combined to capture the exact geometry, texture, and optical material properties of artefacts to produce highly accurate photo-realistic representations. The unique setup allows to shorten the time needed for digitization to several minutes per artefact instead of hours, as required by conventional 3D scanning methods.
Wonder House
Authors: Onion Rebecca
Published: May 2017

The Brooklyn Children’s Museum, the first children’s museum in the country, aimed its offerings at middle-class children who they saw as independent strivers. In discussing the types of science education available at their museum, the educators who ran the Brooklyn Children’s Museum showed how science education for boys in the early twentieth century was pitched at a higher level than the equivalent offerings for girls.
Temporal and spatial variability of ammonia in urban and agricultural regions of northern Colorado, United States
Authors: Li Yi , Thompson Tammy M. , Van Damme Martin , Chen Xi , Benedict Katherine B. , Shao Yixing , Day Derek , Boris Alexandra , Sullivan Amy P. , Ham Jay , Whitburn Simon , Clarisse Lieven , Coheur Pierre-François , Collett Jr. Jeffrey L.
Published: May 2017

Abstract. Concentrated agricultural activities and animal feeding operations in the northeastern plains of Colorado represent an important source of atmospheric ammonia (NH3). The NH3 from these sources contributes to regional fine particle formation and to nitrogen deposition to sensitive ecosystems in Rocky Mountain National Park (RMNP), located  ∼  80 km to the west. In order to better understand temporal and spatial differences in NH3 concentrations in this source region, weekly concentrations of NH3 were measured at 14 locations during the summers of 2010 to 2015 using Radiello passive NH3 samplers. Weekly (biweekly in 2015) average NH3 concentrations ranged from 2.66 to 42.7 µg m−3, with the highest concentrations near large concentrated animal feeding operations (CAFOs). The annual summertime mean NH3 concentrations were stable in this region from 2010 to 2015, providing a baseline against which concentration changes associated with future changes in regional NH3 emissions can be assessed. Vertical profiles of NH3 were also measured on the 300 m Boulder Atmospheric Observatory (BAO) tower throughout 2012. The highest NH3 concentration along the vertical profile was always observed at the 10 m height (annual average concentration of 4.63 µg m−3), decreasing toward the surface (4.35 µg m−3) and toward higher altitudes (1.93 µg m−3). The NH3 spatial distributions measured using the passive samplers are compared with NH3 columns retrieved by the Infrared Atmospheric Sounding Interferometer (IASI) satellite and concentrations simulated by the Comprehensive Air Quality Model with Extensions (CAMx). The satellite comparison adds to a growing body of evidence that IASI column retrievals of NH3 provide very useful insight into regional variability in atmospheric NH3, in this case even in a region with strong local sources and sharp spatial gradients. The CAMx comparison indicates that the model does a reasonable job simulating NH3 concentrations near sources but tends to underpredict concentrations at locations farther downwind. Excess NH3 deposition by the model is hypothesized as a possible explanation for this trend.
Technical note: Boundary layer height determination from lidar for improving air pollution episode modeling: development of new algorithm and evaluation
Authors: Yang Ting , Wang Zifa , Zhang Wei , Gbaguidi Alex , Sugimoto Nobuo , Wang Xiquan , Matsui Ichiro , Sun Yele
Published: May 2017

Abstract. Predicting air pollution events in the low atmosphere over megacities requires a thorough understanding of the tropospheric dynamics and chemical processes, involving, notably, continuous and accurate determination of the boundary layer height (BLH). Through intensive observations experimented over Beijing (China) and an exhaustive evaluation of existing algorithms applied to the BLH determination, persistent critical limitations are noticed, in particular during polluted episodes. Basically, under weak thermal convection with high aerosol loading, none of the retrieval algorithms is able to fully capture the diurnal cycle of the BLH due to insufficient vertical mixing of pollutants in the boundary layer associated with the impact of gravity waves on the tropospheric structure. Consequently, a new approach based on gravity wave theory (the cubic root gradient method: CRGM) is developed to overcome such weakness and accurately reproduce the fluctuations of the BLH under various atmospheric pollution conditions. Comprehensive evaluation of CRGM highlights its high performance in determining BLH from lidar. In comparison with the existing retrieval algorithms, CRGM potentially reduces related computational uncertainties and errors from BLH determination (strong increase of correlation coefficient from 0.44 to 0.91 and significant decreases of the root mean square error from 643 to 142 m). Such a newly developed technique is undoubtedly expected to contribute to improving the accuracy of air quality modeling and forecasting systems.
Long-term analysis of clear-sky new particle formation events and nonevents in Hyytiälä
Authors: Dada Lubna , Paasonen Pauli , Nieminen Tuomo , Buenrostro Mazon Stephany , Kontkanen Jenni , Peräkylä Otso , Lehtipalo Katrianne , Hussein Tareq , Petäjä Tuukka , Kerminen Veli-Matti , Bäck Jaana , Kulmala Markku
Published: May 2017

Abstract. New particle formation (NPF) events have been observed all around the world and are known to be a major source of atmospheric aerosol particles. Here we combine 20 years of observations in a boreal forest at the SMEAR II station (Station for Measuring Ecosystem–Atmosphere Relations) in Hyytiälä, Finland, by building on previously accumulated knowledge and by focusing on clear-sky (noncloudy) conditions. We first investigated the effect of cloudiness on NPF and then compared the NPF event and nonevent days during clear-sky conditions. In this comparison we considered, for example, the effects of calculated particle formation rates, condensation sink, trace gas concentrations and various meteorological quantities in discriminating NPF events from nonevents. The formation rate of 1.5 nm particles was calculated by using proxies for gaseous sulfuric acid and oxidized products of low volatile organic compounds, together with an empirical nucleation rate coefficient. As expected, our results indicate an increase in the frequency of NPF events under clear-sky conditions in comparison to cloudy ones. Also, focusing on clear-sky conditions enabled us to find a clear separation of many variables related to NPF. For instance, oxidized organic vapors showed a higher concentration during the clear-sky NPF event days, whereas the condensation sink (CS) and some trace gases had higher concentrations during the nonevent days. The calculated formation rate of 3 nm particles showed a notable difference between the NPF event and nonevent days during clear-sky conditions, especially in winter and spring. For springtime, we are able to find a threshold equation for the combined values of ambient temperature and CS, (CS (s−1) > −3.091  ×  10−5  ×  T (in Kelvin) + 0.0120), above which practically no clear-sky NPF event could be observed. Finally, we present a probability distribution for the frequency of NPF events at a specific CS and temperature.
Effect of anthropogenic aerosol emissions on precipitation in warm conveyor belts in the western North Pacific in winter – a model study with ECHAM6-HAM
Authors: Joos Hanna , Madonna Erica , Witlox Kasja , Ferrachat Sylvaine , Wernli Heini , Lohmann Ulrike
Published: May 2017

Abstract. While there is a clear impact of aerosol particles on the radiation balance, whether and how aerosol particles influence precipitation is controversial. Here we use the ECHAM6-HAM global climate model coupled to an aerosol module to analyse whether an impact of anthropogenic aerosol particles on the timing and amount of precipitation can be detected in North Pacific warm conveyor belts. Warm conveyor belts are the strongest precipitation-producing airstreams in extratropical cyclones and are identified here with a Lagrangian technique, i.e. by objectively identifying the most strongly ascending trajectories in North Pacific cyclones. These conveyor belts have been identified separately in 10-year ECHAM6-HAM simulations with present-day and pre-industrial aerosol conditions. Then, the evolution of aerosols and cloud properties has been analysed in detail along the identified warm conveyor belt trajectories. The results show that, under present-day conditions, some warm conveyor belt trajectories are strongly polluted (i.e. high concentrations of black carbon and sulfur dioxide) due to horizontal transport from eastern Asia to the oceanic region where warm conveyor belts start their ascent. In these polluted trajectories a weak delay and reduction of precipitation formation occurs compared to clean warm conveyor belt trajectories. However, all warm conveyor belts consist of both polluted and clean trajectories at the time they start their ascent, and the typically more abundant clean trajectories strongly reduce the aerosol impact from the polluted trajectories. The main conclusion then is that the overall amount of precipitation is comparable in pre-industrial conditions, when all warm conveyor belt trajectories are clean, and in present-day conditions, when warm conveyor belts consist of a mixture of clean and polluted trajectories.
Nitro-polycyclic aromatic hydrocarbons – gas–particle partitioning, mass size distribution, and formation along transport in marine and continental background air
Authors: Lammel Gerhard , Mulder Marie D. , Shahpoury Pourya , Kukučka Petr , Lišková Hana , Přibylová Petra , Prokeš Roman , Wotawa Gerhard
Published: May 2017

Abstract. Nitro-polycyclic aromatic hydrocarbons (NPAH) are ubiquitous in polluted air but little is known about their abundance in background air. NPAHs were studied at one marine and one continental background site, i.e. a coastal site in the southern Aegean Sea (summer 2012) and a site in the central Great Hungarian Plain (summer 2013), together with the parent compounds, PAHs. A Lagrangian particle dispersion model was used to track air mass history. Based on Lagrangian particle statistics, the urban influence on samples was quantified for the first time as a fractional dose to which the collected volume of air had been exposed. At the remote marine site, the 3–4-ring NPAH (sum of 11 targeted species) concentration was 23.7 pg m−3 while the concentration of 4-ring PAHs (6 species) was 426 pg m−3. The most abundant NPAHs were 2-nitrofluoranthene (2NFLT) and 3-nitrophenanthrene. Urban fractional doses in the range of < 0.002–5.4 % were calculated. At the continental site, the Σ11 3–4-ring NPAH and Σ6 4-ring PAH were 58 and 663 pg m−3, respectively, with 9-nitroanthracene and 2NFLT being the most concentrated amongst the targeted NPAHs. The NPAH levels observed in the marine background air are the lowest ever reported and remarkably lower, by more than 1 order of magnitude, than 1 decade before. Day–night variation of NPAHs at the continental site reflected shorter lifetime during the day, possibly because of photolysis of some NPAHs. The yields of formation of 2NFLT and 2-nitropyrene (2NPYR) in marine air seem to be close to the yields for OH-initiated photochemistry observed in laboratory experiments under high NOx conditions. Good agreement is found for the prediction of NPAH gas–particle partitioning using a multi-phase poly-parameter linear free-energy relationship. Sorption to soot is found to be less significant for gas–particle partitioning of NPAHs than for PAHs. The NPAH levels determined in the south-eastern outflow of Europe confirm intercontinental transport potential.
Reanalysis comparisons of upper tropospheric/lower stratospheric jets and multiple tropopauses
Authors: Manney Gloria L. , Hegglin Michaela I. , Lawrence Zachary D. , Wargan Krzysztof , Millán Luis F. , Schwartz Michael J. , Santee Michelle L. , Lambert Alyn , Pawson Steven , Knosp Brian W. , Fuller Ryan A. , Daffer William H.
Published: May 2017

Abstract. The representation of upper tropospheric/lower stratospheric (UTLS) jet and tropopause characteristics is compared in five modern high-resolution reanalyses for 1980 through 2014. Climatologies of upper tropospheric jet, subvortex jet (the lowermost part of the stratospheric vortex), and multiple tropopause frequency distributions in MERRA (Modern Era Retrospective Analysis for Research and Applications), ERA-I (the ECMWF interim reanalysis), JRA-55 (the Japanese 55-year Reanalysis), and CFSR (the Climate Forecast System Reanalysis) are compared with those in MERRA-2. Differences between alternate products from individual reanalysis systems are assessed; in particular, a comparison of CFSR data on model and pressure levels highlights the importance of vertical grid spacing. Most of the differences in distributions of UTLS jets and multiple tropopauses are consistent with the differences in assimilation model grids and resolution: For example, ERA-I (with coarsest native horizontal resolution) typically shows a significant low bias in upper tropospheric jets with respect to MERRA-2, and JRA-55 a more modest one, while CFSR (with finest native horizontal resolution) shows a high bias with respect to MERRA-2 in both upper tropospheric jets and multiple tropopauses. Vertical temperature structure and grid spacing are especially important for multiple tropopause characterization. Substantial differences between MERRA and MERRA-2 are seen in mid- to high-latitude southern hemisphere winter upper tropospheric jets and multiple tropopauses, and in the upper tropospheric jets associated with tropical circulations during the solstice seasons; some of the largest differences from the other reanalyses are seen in the same times and places. Very good qualitative agreement among the reanalyses is seen between the large scale climatological features in UTLS jet and multiple tropopause distributions. Quantitative differences may, however, have important consequences for transport and variability studies. Our results highlight the importance of considering reanalyses differences in UTLS studies, especially in relation to resolution and model grids; this is particularly critical when using high-resolution reanalyses as an observational reference for evaluating global chemistry climate models.
Heterogeneous reaction of HO2 with airborne TiO2 particles and its implication for climate change mitigation strategies
Authors: Moon Daniel R. , Taverna Giorgio S. , Anduix-Canto Clara , Ingham Trevor , Chipperfield Martyn P. , Seakins Paul W. , Baeza-Romero Maria-Teresa , Heard Dwayne E.
Published: May 2017

Abstract. One geoengineering mitigation strategy for global temperature rises resulting from the increased concentrations of greenhouse gases is to inject particles into the stratosphere to scatter solar radiation back to space, with TiO2 particles emerging as a possible candidate. Uptake coefficients of HO2, γ(HO2), onto sub-micrometre TiO2 particles were measured at room temperature and different relative humidities (RH) using an atmospheric pressure aerosol flow tube coupled to a sensitive HO2 detector. Values of γ(HO2) increased from 0.021 ± 0.001 to 0.036 ± 0.007 as the RH was increased from 11 % to 66 %, and the increase in γ(HO2) correlated with the number of monolayers of water surrounding the TiO2 particles. The impact of the uptake of HO2 onto TiO2 particles on stratospheric concentrations of HO2 and O3 was simulated using the TOMCAT three-dimensional chemical transport model. The model showed that by injecting the amount of TiO2 required to achieve the same cooling effect as the Mt. Pinatubo eruption, heterogeneous reactions between HO2 and TiO2 would have a negligible effect on stratospheric concentrations of HO2 and O3.
The influence of episodic flooding on a pelagic ecosystem in the East China Sea
Authors: Chen Chung-Chi , Gong Gwo-Ching , Chou Wen-Chen , Chung Chih-Ching , Hsieh Chih-Hao , Shiah Fuh-Kwo , Chiang Kuo-Ping
Published: May 2017

Abstract. This study was designed to determine the effects of flooding on a pelagic ecosystem in the East China Sea (ECS) with a focus on plankton activity and plankton community respiration (CR). In July 2010, a flood occurred in the Changjiang River. As a comparison, a variety of abiotic and biotic parameters were monitored during this flooding event and during a non-flooding period (July 2009). During the flood, the Changjiang diluted water (CDW) zone covered almost two-thirds of the ECS, which was approximately 6 times the area covered during the non-flooding period. The mean nitrate concentration was 3-fold higher during the 2010 flood (6.2 vs. 2.0 µM in 2009). CR was also higher in the 2010 flood: 105.6 mg C m−3 d−1 vs. only 73.2 mg C m−3 d−1 in 2009. The higher CR in 2010 could be attributed to phytoplankton respiration, especially at stations in the CDW zone that were not previously characterized by low sea surface salinity in 2009. In addition, zooplankton (> 330 µm) were another important component contributing to the high CR rate observed during the 2010 flood; this was a period also associated with a significant degree of fCO2 drawdown. These results collectively suggest that the 2010 flood had a significant effect on the carbon balance in the ECS. This effect might become more pronounced in the future, as extreme rainfall and flooding events are predicted to increase in both frequency and magnitude due to climate change.
Eurasian contribution to the last glacial dust cycle: how are loess sequences built?
Authors: Rousseau Denis-Didier , Svensson Anders , Bigler Matthias , Sima Adriana , Steffensen Jorgen Peder , Boers Niklas
Published: May 2017

Abstract. The last 130 000 years have been marked by pronounced millennial scale climate variability, which strongly impacted the terrestrial environments of the Northern Hemisphere especially at middle latitudes. Identifying the trigger of these variations, which are most likely associated with strong couplings between the ocean and the atmosphere, still remains a key question. Here, we show that the analysis of δ18O and dust in the Greenland ice cores, and a critical study of their source variations, reconciles these records with those observed on the Eurasian continent. We demonstrate the link between European and Chinese loess sequences, dust records in Greenland, and variations of the North Atlantic sea ice extent. The sources of the emitted and transported dust material are variable and relate to different environments corresponding to present desert areas, but also hidden regions related to lower sea level stands, dry rivers, or zones close to the frontal moraines of the main Northern Hemisphere ice sheets. We anticipate our study to be at the origin of more sophisticated and elaborated investigations of millennial and sub-millennial continental climate variability on the Northern Hemisphere.
Carbon–nitrogen interactions in idealized simulations with JSBACH (version 3.10)
Authors: Goll Daniel S. , Winkler Alexander J. , Raddatz Thomas , Dong Ning , Prentice Ian Colin , Ciais Philippe , Brovkin Victor
Published: May 2017

Abstract. Recent advances in the representation of soil carbon decomposition and carbon–nitrogen interactions implemented previously into separate versions of the land surface scheme JSBACH are here combined in a single version, which is set to be used in the upcoming 6th phase of coupled model intercomparison project (CMIP6).Here we demonstrate that the new version of JSBACH is able to reproduce the spatial variability in the reactive nitrogen-loss pathways as derived from a compilation of δ15N data (R = 0. 76, root mean square error (RMSE)  = 0. 2, Taylor score  = 0. 83). The inclusion of carbon–nitrogen interactions leads to a moderate reduction (−10 %) of the carbon-concentration feedback (βL) and has a negligible effect on the sensitivity of the land carbon cycle to warming (γL) compared to the same version of the model without carbon–nitrogen interactions in idealized simulations (1 % increase in atmospheric carbon dioxide per year). In line with evidence from elevated carbon dioxide manipulation experiments, pronounced nitrogen scarcity is alleviated by (1) the accumulation of nitrogen due to enhanced nitrogen inputs by biological nitrogen fixation and reduced losses by leaching and volatilization. Warming stimulated turnover of organic nitrogen further counteracts scarcity.The strengths of the land carbon feedbacks of the recent version of JSBACH, with βL = 0. 61 Pg ppm−1 and γL = −27. 5 Pg °C−1, are 34 and 53 % less than the averages of CMIP5 models, although the CMIP5 version of JSBACH simulated βL and γL, which are 59 and 42 % higher than multi-model average. These changes are primarily due to the new decomposition model, indicating the importance of soil organic matter decomposition for land carbon feedbacks.
Passive Acoustic Measurement of Bedload Grain Size Distribution using the Self-Generated Noise
Authors: Petrut Teodor I. , Geay Thomas , Gervaise Cédric , Belleudy Philippe , Zanker Sebastien
Published: May 2017

Abstract. Monitoring sediment transport processes in rivers is of particular interest to engineers and scientists to assess the stability of rivers and hydraulic structures. Various methods for sediment transport processes description were proposed using conventional or surrogate measurement techniques. This paper addresses the topic of the passive acoustic monitoring of bedload transport in rivers and especially the estimation of the bedload grain size distribution from self-generated noise. It discusses the feasibility of linking the acoustic signal spectrum shape to bedload-grain sizes involved in elastic impacts with the bed river treated as a massive slab. Bedload grain size distribution is estimated by a regularized algebraic inversion scheme fed with the power spectrum density of river noise estimated from one hydrophone. The inversion methodology relies upon a physical model which predicts the acoustic field generated by the collision between rigid bodies. Here it is proposed an analytic model of the acoustic power spectrum generated by the impacts between a sphere and a slab. The proposed model is written as linear system of analytic power spectra weighted by the grain size distribution. The algebraic system of equations is then solved by least square optimization and solution regularization methods. The result of inversion leads directly to the estimation of the bedload grain size distribution. The inversion method was applied on real acoustic data from passive acoustics experiments realized on the Isère River, in France. The inversion of in situ measured spectra reveals good estimations of grain size distribution, fairly close to what was estimated by physical sampling instruments. These results illustrate the potential of the hydrophone technique to be used as a standalone method that could ensures high spatial and temporal resolution measurements for sediment transport in rivers.
Impacts of changes in groundwater recharge on the isotopic composition and geochemistry of seasonally ice-covered lakes: insights for sustainable management
Authors: Arnoux Marie , Barbecot Florent , Gibert-Brunet Elisabeth , Gibson John , Noret Aurélie
Published: May 2017

Abstract. Lakes are under increasing pressure due to widespread anthropogenic impacts related to rapid development and population growth. Accordingly, many lakes are currently undergoing a systematic decline in water quality. Recent studies have highlighted that global warming and the subsequent change in water use may further exasperate eutrophication in lakes. Lake evolution depends strongly on hydrologic balance, and therefore on groundwater connectivity. Groundwater also influences the sensitivity of lacustrine ecosystems to climate and environmental changes, and governs their resilience. Improved characterization of groundwater exchange with lakes is needed today for lake preservation, lake restoration, and for sustainable management of lake water quality into the future. Small groundwater-connected lakes were chosen to simulate changes in water balance and water quality expected under future climate change scenarios, namely Representative Concentration Pathways (RCP) 4.5 and 8.5. Contemporary baseline conditions, including isotope mass balance and geochemical characteristics, were determined through an intensive field-based research program prior to the simulations. Results highlight that future lake geochemistry and isotopic composition trends will depend on four main parameters: location (therefore climate conditions), lake catchment size (which impacts the intensity of the flux change), lake volume (which impacts the range of variation), and lake G-index (i.e., the percentage of groundwater that makes up total lake inflows), the latter being the dominant control on water balance conditions, as revealed by the sensitivity of lake isotopic composition. Based on these model simulations, stable isotopes appear to be especially useful for detecting changes in recharge to lakes with a G-index of between 50 % and 80 %, but response is non-linear. Simulated monthly trends reveal that evolution of annual lake isotopic composition can be dampened by opposing monthly recharge fluctuations. It is also shown that changes in water quality in groundwater-connected lakes depend significantly on lake location and on the intensity of recharge change.
Evaluation of GPM IMERG Early, Late, and Final rainfall estimates with WegenerNet gauge data in southeast Austria
Authors: O Sungmin , Foelsche Ulrich , Kirchengast Gottfried , Fuchsberger Jürgen , Tan Jackson , Petersen Walter A.
Published: May 2017

Abstract. The Global Precipitation Measurement (GPM) Integrated Multi-satellite Retrievals (IMERG) products provide quasi-global (60° N-60° S) precipitation estimates, beginning March 2014, from the combined use of passive microwave (PMW) and infrared (IR) satellites comprising the GPM constellation. The IMERG products are available in the form of near-real-time data, i.e. IMERG Early and Late, and of post-real-time research data, i.e. IMERG Final, after monthly rain gauge analysis is received and taken into account. In this study, IMERG Early, Late, and Final (IMERG-E, -L, and -F) half-hourly rainfall estimates are compared with gauge-based gridded rainfall data from the WegenerNet Feldbach Region (WEGN) high density climate station network in southeast Austria. The comparison is conducted over two IMERG 0.1° x 0.1° grid cells, entirely covered by 40 and 39 WEGN stations each, with data during the extended summer season (April–October) for the first two years of the GPM mission. The entire data are divided into two rainfall intensity ranges (low and high) and two seasons (warm and hot), and we evaluate the performance of IMERG using both statistical and graphical methods. Results show that IMERG-F rainfall estimates are in the best overall agreement with the WEGN data, followed by IMERG-L and IMERG-E estimates, particularly for the hot season. We also illustrate, through rainfall event cases, how insufficient PMW sources and errors in motion vectors can lead to wide discrepancies in the IMERG estimates. Finally, by applying the method of Villariniand Krajewski (2007), we find that IMERG-F half-hourly rainfall estimates can be regarded as a 25-min gauge accumulation, with an offset of +40 min relative to its nominal time.
Scale effect challenges in urban hydrology highlighted with a distributed hydrological model
Authors: Ichiba Abdellah , Gires Auguste , Tchiguirinskaia Ioulia , Schertzer Daniel , Bompard Philippe , Ten Veldhuis Marie-Claire
Published: May 2017

Abstract. Nowadays, hydrological models are extensively used in urban water management, future development scenario evaluation and research activities. A growing interest is devoted to the development of fully distributed and grid based models, following the increase of computation capabilities. The availability of high resolution GIS information is needed for such models implementation to understand flooding issues at very small scales. However, some complex issues about scaling effects still remain a serious issue in urban hydrology. The choice of an appropriate spatial resolution is a crucial problem, and the obtained model performance depends highly on the chosen implementation scale. In this paper we propose a two step investigation framework using scaling effects in urban hydrology. In the first step fractal tools are used to highlight the scale dependency observed within distributed data used to describe the catchment heterogeneity, both the structure of the sewer network and the distribution of impervious areas are analyzed. Then an intensive multi-scale modeling work is carried out to understand scaling effects on hydrological model performance. Investigations were conducted using a fully distributed and physically based model, Multi-Hydro, developed at Ecole des Ponts ParisTech (Multi-Hydro (2015)). The model was implemented at 17 spatial resolution ranging from 100 m to 5 m. Results coming out from this work demonstrate scale effect challenges in urban hydrology modeling. In fact, fractal concept highlights the scale dependency observed within distributed data used to implement hydrological models. Patterns of geophysical data change when we change the observation pixel size. The multi-scale modeling investigation performed with Multi-Hydro model at 17 spatial resolutions confirms scaling effect on hydrological model performance. Results were analyzed at three ranges of scales identified in the fractal analysis and confirmed in the modeling work. In the meantime, this work also discussed some issues remaining in urban hydrology modeling such as the availability of high quality data at higher resolutions and, model numerical instabilities as well as the computation time requirements. But still the principal findings of this paper allow replacing traditional methods of model calibration by innovative methods of model resolution alteration based on the spatial data variability and scaling of flows in urban hydrology.
An Adaptive Semi-Lagrangian Advection Model for Transport of Volcanic Emissions in the Atmosphere
Authors: Gerwing Elena , Hort Matthias , Behrens Jörn , Langmann Bärbel
Published: May 2017

Abstract. Dispersion of volcanic emissions in the Earth atmosphere is of interest for climate research, air traffic control as well as human wellbeing. Current volcanic emission dispersion models rely on fixed grid structures that often are not able to resolve the fine filamented structure of volcanic emissions while being transported in the atmosphere. Here we extend an existing adaptive semi-Lagrangian advection model for volcanic emissions including the sedimentation of volcanic ash. The advection of volcanic emissions is driven by a pre-calculated wind field. For evaluation of the model, the explosive eruption of Mount Pinatubo in June 1991 is chosen, which was one of the largest eruptions in the 20th Century. We compare our simulations of the climactic eruption on June 15, 1991 to satellite data of the Pinatubo ash cloud and evaluate different sets of input parameters. We could reproduce the general advection of the Pinatubo ash cloud and owing to the adaptive mesh, simulations could be performed at a high local resolution while minimizing computational cost. Differences to the observed ash cloud are attributed to uncertainties in the input parameters and the pass by of Typhoon Yunya, which is probably not completely resolved in the wind data used to drive the model. Best results were achieved for simulations with multiple ash particle sizes.
El gobierno interno de las mayores cooperativas agroalimentarias españolas y su relación con el rendimiento
Authors: Meliá Martí Elena , Carnicer Andrés Mª Pía , Juliá Igual Juan F.
Published: May 2017

El presente estudio pretende analizar la relación existente entre las estructuras de gobierno de las mayores cooperativas agroalimentarias españolas y sus resultados empresariales, para comprobar -si al igual que se ha demostrado en estudios recientes sobre cooperativas agroalimentarias europeas-, las cooperativas que muestran una mayor innovación en sus estructuras de gobierno (en aspectos tales como la profesionalización de la gestión, inclusión de voto proporcional o presencia de expertos externos en los Consejos Rectores o Supervisores), presentan mejores resultados que las cooperativas que no poseen dichos atributos. Los resultados obtenidos corroboran que el rendimiento (medido en facturación por socio) de las cooperativas agroalimentarias españolas analizadas se ve afectado positivamente por la introducción de algunas innovaciones en sus sistemas de gobierno interno, como es el caso de la inclusión de expertos externos en el Consejo Rector y en el Consejo Supervisor. Además, el estudio arroja otras conclusiones vinculadas con la envergadura o dimensión de la cooperativa, constatándose que las cooperativas de mayor dimensión (medida en este caso por el volumen de activos) son capaces de proporcionar un mayor y significativo rendimiento; a diferencia de lo que ocurre con el número de socios, cuyo efecto en el rendimiento es significativo y negativo.
Exploring School Counselors’ Motivations to Work with LGBTQQI Students in Schools: A Q Methodology Study
Authors: Goodrich Kristopher M.
Published: May 2017

This study surveyed a national sample of school counselors who were members of ASCA to understand what motivated their work, or not, with lesbian, gay, bisexual, transgender, queer, questioning, and intersex (LGBTQQI) students in school. The author implemented Q methodology to collect and analyze the data, and results provide scholars and professional development providers with an understanding of how they might be able to motivate different types of school counselors to work with LGBTQQI students.