bluuebunny/crossref_metadata_2025 huggingface dataset:
La notion d'apprentissage dans la perspective de l'épistémologie génétique
Authors: Dolle Jean-Marie
Published: December 2014

La vie étant adaptation d’un sujet vivant à ses milieux de vie dans l’interaction qu’il établit avec eux. L’adaptation est en elle-même une activité qui produit des états dits « adaptés ». Or, comme toute activité d’un « sujet », qu’il soit végétal ou animal, développe des structures, c’est en s’adaptant qu’il les exerce et se donne celles qui lui sont nécessaires pour une meilleure adaptation. C’est cette activité où se manifestent des phénomènes d’assimilation et d’accommodation qui constitue à proprement parler l’apprentissage. Ce dernier s’exerçant dans l’interaction « sujet-objet » ou, plus généralement, « sujet-milieu », s’entend aussi bien du milieu que des « objets » qu’il contient. Le milieu pédagogique, est, par extension, celui des adaptations dans lesquelles l’enfant puis le jeune adulte, « apprend » les contenus pédagogiques et, dans certains cas, les contenus et les conduites professionnelles en les construisant et les reconstruisant sans cesse. Ce faisant, il construit et reconstruit les structures qui lui permettent d’apprendre. Si l’interaction est ainsi la marque de tout apprentissage, que dire des méthodes pédagogiques qui, s’appuyant principalement sur la mémoire, répandent des « savoirs » qu’elles demandent de répéter ou de reproduire telles quelles, mécaniquement, au détriment de la pensée ? Ne s’appuyant que sur les « états » du réel et du savoir, faisant fi des transformations qui les produisent, ne contribueraient-elles pas à tuer la pensée ?
Une expérimentation improbable pour désapprendre
Authors: Bureau Sylvain
Published: December 2014

Dans les formations de gestion, la vision traditionnelle de l’apprentissage est linaire et incrémentale : une fois les notions de base maîtrisées, il faut approfondir ses connaissances et développer une expertise spécialisée. Cette approche est tout à fait justifiée dans nombre de cursus académiques mais elle ne peut l’être au démarrage d’une formation en entrepreneuriat. A ce stade, le plus urgent, l’enjeu premier est avant tout de désapprendre. Les connaissances passées ne sont pas nécessairement obsolètes mais elles limitent l’espace des possibles, elles enferment dans des modes de raisonnement et d’action bien souvent inappropriées pour entreprendre. Pour désapprendre, c’est-à-dire détruire certaines connaissances, croyances et routines passées pour développer de nouvelles heuristiques et comportements, le dispositif pédagogique se doit d’être non seulement en rupture avec le contenu traditionnellement enseigné mais aussi avec la symbolique habituelle. Nous présentons dans le cadre de ce papier une expérimentation, Improbable , qui vise à produire un tel effet. Son principe peut se résumer par la double exigence suivante : d’une part offrir aux étudiants un rôle totalement décalé au regard de leur formation passée ; et d’autre part, leur permettre de développer des activités qui approximent le travail de l’entrepreneur. Pour répondre à un tel énoncé, nous avons retenu la figure de l’artiste : durant quatre jours, les étudiants ont adopté cette posture, à la limite de l’imposture.
La pratique groupale du désapprentissage
Authors: Metge Marielle , Agostinelli Serge
Published: December 2014

Ce texte a pour ambition de mettre en relation compétence communicative et désapprendre organisationnel. En effet, la notion de participation dans les communautés de pratique joue un rôle de conflit sociocognitif. Ce conflit engendre une sorte de déstabilisation des connaissances et le désapprendre qui autorise alors l’intégration de changements techniques ou organisationnels de ces communautés. La compétence communicative sert alors de levier de désapprentissage à travers le discours et à la construction d’un sens commun. Les individus se construisent alors l’illusion d’une complétude informationnelle dépendante d’un déroulement qu’ils « savent » logique puisque socialement construit. Une ellipse informationnelle forme ainsi, un raccourci de la pensée qui ne nuit pas à l’intelligibilité de l’ensemble et allège la situation.
La spiritualité
Authors: Mériade Laurent , Mainetti Nicolas
Published: December 2014

Les principaux travaux portant sur la spiritualité dans les entreprises accordent une place essentielle à l’expression de la spiritualité des salariés (Karakas, 2010, Mitroff, 2000) ou celle des dirigeants (Voynnet Fourboul, 2011) dans leur réussite personnelle ou collective. Dans cet article, nous faisons l’hypothèse que le contexte exemplaire des entreprises chinoises offre la possibilité d’évaluer cette relation à travers les perceptions des salariés. Pour cela, nous proposons sur le plan théorique de vérifier les relations existantes entre la spiritualité des salariés chinois et leur réussite personnelle ainsi que celle de leur organisation en mobilisant la littérature relative à la pensée et la philosophie chinoises (Granet, 1934 ; Jullien, 1996, 2005, 2009 ; Gernet, 2001 ; Barbier, 2001 ; Billeter, 2006). Sur un plan pratique, nous tentons de décrire les valeurs personnelles (Cavanagh, 1999) qui guident leurs comportements et les relations avec leur bien être et leur réussite personnelle et collective à partir d’une étude exploratoire auprès des salariés de deux entreprises publique et privée chinoises.
L'irrationnel, fondement de privilèges exclusifs et abusifs
Authors: Atkouf Omar
Published: December 2014

Dès la première moitié du 19 ème siècle, un Alexis de Tocqueville notait d’une certaine façon (dans De la démocratie en Amérique ), que, en fait de démocratie et de nouvel État de droit, s’érigeait aux États – Unis, un certes, nouvel ordre social («nouveau monde»), mais de type, apparemment «nouvelle aristocratie», que réellement «nouvelle démocratie». Il y notait, comme le feront aussi, bien plus tard et chacun à sa façon, des Veblen ou Schumpeter..., qu’il naissait plutôt, en ce nouveau monde, une aristocratie d’un genre inédit : toute terne et bassement matérialiste – prosaïque, qui entendait s’arroger les privilèges de l’ancienne noblesse du vieux monde (féodal-monarchiste) sur la base d’une non moins inédite source de légitimité : la propriété privée et la fortune. Voici donc le grand problème que devaient affronter ces «nouveaux aristocrates» : comment légitimer leur désir de pouvoir absolu, d’accaparement de privilèges, et de remplacement de l’ancienne noblesse en tant que classe dominante. Or tout pouvoir absolu nécessite, pour se légitimer, l’affirmation d’une origine, aura, dimension... transcendant la simple condition humaine : les théories du leadership ne sont-elles pas une sorte de ‘fiction’ remplissant ce rôle ?
Le biais d'auto-complaisance dans la création immédiate de connaissances, issue d'un échec
Authors: Cusin Julien
Published: December 2014

La presse managériale grand public souligne régulièrement les vertus positives de l’acquisition de connaissances par l’échec. Pourtant, malgré un intérêt grandissant pour cet axe de recherche toujours en phase d’émergence (Carmeli, 2007), la littérature en management n’a, jusqu’à présent, jamais permis d’étayer empiriquement cette thèse. Au contraire, les principaux travaux sur le sujet (Baumard et Starbuck, 2005 ; Cannon et Edmondson, 2005 ; Carmeli et Schaubroeck, 2008) nuancent très fortement le mythe de l’acquisition de connaissances par l’échec. Dans cette recherche, nous nous proposons donc d’étudier, en profondeur, une cause supposée de non acquisition de connaissances – en l’occurrence, le biais d’auto-complaisance (Miller et Ross, 1975) – et d’en vérifier l’existence sur le plan empirique. Plus encore, nous cherchons à étudier les liens entre l’auto-complaisance des individus et la performance de l’organisation. Nous nous interrogeons aussi sur la manière dont le biais d’intéressement dans l’attribution se manifeste dans la durée. Pour mener à bien cette réflexion, nous avons choisi d’étudier le discours des entraîneurs de football (Ligue 1), en conférence de presse, le soir d’une défaite, au cours de la saison 2010-2011. Il en ressort plusieurs résultats théoriques intéressants. Tout d’abord, l’existence d’un biais d’auto-complaisance n’est pas confirmée dans cet article. En outre, nous montrons que les individus les moins auto-complaisants ne sont pas ceux qui obtiennent in fine les meilleurs résultats sur le plan collectif. Enfin, nous soulignons l’importance du contexte social dans l’analyse rétrospective d’un échec. En revanche, nous mettons en évidence que l’accumulation d’échecs dans le temps et les situations de stress n’accentuent pas le biais égocentrique.
Une approche microethnographique et multi-située en organisation
Authors: Grosjean Sylvie
Published: December 2014

L’objectif de cet article est de présenter de manière détaillée la méthodologie mise en œuvre lors d’une recherche ethnographique menée au sein d’une compagnie d’arpentage. Le but de cette recherche est d’analyser et de comprendre comment une « manière de voir » organisationnelle est constituée interactionnelle et partagée afin de soutenir la production d’expertise. Pour illustrer notre approche, nous utilisons la métaphore du « zooming in/out  » (Nicolini 2009, 2013) pour discuter du double mouvement de « zoom avant » sur les détails de l’accomplissement des activités quotidiennes (via des enregistrements vidéo des interactions) et de « zoom arrière », mouvement par lequel nous élargissons la portée des observations en suivant les agencements sociotechniques.
L'ethnographe au pays des cliniciens
Authors: Côté André
Published: December 2014

Le professeur Côté partage avec nous son expérience d’ethnographe au sein d’organisations de soin. Il propose ici une réflexion sur sa pratique sous la forme d’un témoignage portant sur son séjour au pays des cliniciens. L’objectif de ce témoignage est de documenter sa démarche ethnographique qui a eu cours, entre octobre 1995 et juin 2000, au sein d’un centre hospitalier spécialisé québécois, situé en région, et vivant un changement organisationnel majeur. Il profite de l’occasion pour nous faire part de quelques découvertes insoupçonnées découlant de ses travaux de recherche dont notamment la simplicité de l’hôpital en tant qu’entité organisationnelle et le rôle à la fois prédominant et intégrateur de la confiance dans la transformation des pratiques cliniques. Il partage avec nous ses craintes, ses incertitudes et ses angoisses récurrentes ayant trait à l’accès au terrain de recherche, à la stratégie d’observation à adopter, à la gestion des donnés et à la crédibilité et la qualité des donnés. Pour terminer, il souligne la contribution de la démarche ethnographique à la compréhension des enjeux auxquels font face les organisations d’aujourd’hui.
De los dioses a los hombres: Un recorrido histórico del descubrimiento de los elementos químicos
Authors: Pellón González I.
Published: December 2014

Llegar hasta la aparentemente sencilla Tabla Periódica de los Elementos le ha costado a la humanidad enormes esfuerzos a lo largo de miles de años. En este trabajo se recorre la historia del descubrimiento de los elementos químicos desde la Prehistoria hasta nuestros días, reflejando las controversias que se suscitaron y reivindicando el importante trabajo que realizaron los alquimistas en el progreso de los conocimientos, ya que la alquimia tuvo un período de existencia de muchos miles de años, mientras que la “Química” oficialmente establecida como ciencia en el siglo XVIII consta de sólo unos cientos de años. Aún así, al realizar un balance de la progresión del descubrimiento y aislamiento de los elementos químicos a lo largo de la Historia se puede comprobar el elevado número de elementos identificados en los siglos XIX y XX, reflejo del perfeccionamiento de las técnicas instrumentales que facilitaron esta labor.
Seismic retrofitting of timber framed walls
Authors: Gonçalves A. M. , Gomes-Ferreira J. , Guerreiro L. , Branco F.
Published: December 2014

After the 1755 earthquake that destroyed Lisbon, an innovative anti-seismic structural system was developed consisting of a timber skeleton, that included timber framed masonry walls. After more than 250 years these structures need rehabilitation to face the present demands. The research presented in this paper aimed at experimentally characterizing the cyclic behaviour of timber framed walls reinforced with three different methods, namely: (i) elastic-plastic dampers on diagonal braces, (ii) reinforcement of timber connections with steel plates, (iii) application of a reinforced rendering. The elastic-plastic damper showed an unsymmetrical behaviour and some difficulties to implement in practice. The strengthening with reinforced render led to an initial stiffness increase but showed a limited deformation capacity. The walls with reinforcing steel plates at the timber connections showed the best behaviour in terms of strength, stiffness and energy dissipation.
Loose Integration of Local Information to Generate Collaborative Marine Science Knowledge
Authors: Leadbetter Adam , Arko Robert , Chandler Cynthia , Shepherd Adam , Lowry Roy
Published: December 2014

This chapter focuses on improved access to marine science data, enabling researchers to generate new information and knowledge products. The history of controlled vocabulary developments in marine sciences, from paper publications to the Semantic Web, is explored in detail. This history is being furthered through the publication of Linked Open Data, meaning: the publication of clearly identifiable entities; a simple, universal mechanism for retrieving resources; a generic graph-based data model; and publishing explicit relationships to other resources. Progress towards Linked Open Data for marine science is reported in this chapter. As shown by the Data-Information-Knowledge ecosystem, the approach of “small pieces of data loosely joined” provides presentation and organisation to data, which creates information. The use of query endpoints to integrate this information from multiple locations into a knowledge base, which required active collaboration between cooperative partners to truly generate new knowledge and to address emerging science questions, is described.
A CD46-like Molecule Functional in Teleost Fish Represents an Ancestral Form of Membrane-Bound Regulators of Complement Activation
Authors: Tsujikura Masakazu , Nagasawa Takahiro , Ichiki Satoko , Nakamura Ryota , Somamoto Tomonori , Nakao Miki
Published: December 2014

In the complement system, the regulators of complement activation (RCA) play crucial roles in controlling excessive complement activation and in protecting host cell from misdirected attack of complement. Several members of RCA family have been cloned from cyclostome and bony fish species and classified into soluble and membrane-bound type as in mammalian RCA factors. Complement-regulatory functions have been described only for soluble RCA of lamprey and barred sand bass; however, little is known on the biological function of the membrane-bound RCA proteins in the lower vertebrates. In this study, a membrane-bound RCA protein, designated teleost complement-regulatory membrane protein (Tecrem), was cloned and characterized for its complement-regulatory roles. Carp Tecrem, an ortholog of a zebrafish type 2 RCA, ZCR1, consists of four short consensus repeat modules, a serine/threonine/proline-rich domain, a transmembrane region, and a cytoplasmic domain, from the N terminus, as does mammalian CD46. Tecrem showed a ubiquitous mRNA expression in carp tissues, agreeing well with the putative regulatory role in complement activation. A recombinant Chinese hamster ovary cell line bearing carp Tecrem showed a significantly higher tolerance against lytic activity of carp complement and less deposition of C3-S, the major C3 isotypes acting on the target cell, than control Chinese hamster ovary (mock transfectant). Anti-Tecrem mAb enhanced the depositions of carp C3 and two C4 isotypes on autologous erythrocytes. Thus, the present findings provide the evidence of complement regulation by a membrane-bound group 2 RCA in bony fish, implying the host–cell protection is an evolutionarily conserved mechanism in regulation of the complement system.
Antibody Stabilization of Peptide–MHC Multimers Reveals Functional T Cells Bearing Extremely Low-Affinity TCRs
Authors: Tungatt Katie , Bianchi Valentina , Crowther Michael D. , Powell Wendy E. , Schauenburg Andrea J. , Trimby Andrew , Donia Marco , Miles John J. , Holland Christopher J. , Cole David K. , Godkin Andrew J. , Peakman Mark , Straten Per Thor , Svane Inge Marie , Sewell Andrew K. , Dolton Garry
Published: December 2014

Fluorochrome-conjugated peptide–MHC (pMHC) multimers are commonly used in combination with flow cytometry for direct ex vivo visualization and characterization of Ag-specific T cells, but these reagents can fail to stain cells when TCR affinity and/or TCR cell-surface density are low. pMHC multimer staining of tumor-specific, autoimmune, or MHC class II–restricted T cells can be particularly challenging, as these T cells tend to express relatively low-affinity TCRs. In this study, we attempted to improve staining using anti-fluorochrome unconjugated primary Abs followed by secondary staining with anti-Ab fluorochrome-conjugated Abs to amplify fluorescence intensity. Unexpectedly, we found that the simple addition of an anti-fluorochrome unconjugated Ab during staining resulted in considerably improved fluorescence intensity with both pMHC tetramers and dextramers and with PE-, allophycocyanin-, or FITC-based reagents. Importantly, when combined with protein kinase inhibitor treatment, Ab stabilization allowed pMHC tetramer staining of T cells even when the cognate TCR–pMHC affinity was extremely low (KD >1 mM) and produced the best results that we have observed to date. We find that this inexpensive addition to pMHC multimer staining protocols also allows improved recovery of cells that have recently been exposed to Ag, improvements in the recovery of self-specific T cells from PBMCs or whole-blood samples, and the use of less reagent during staining. In summary, Ab stabilization of pMHC multimers during T cell staining extends the range of TCR affinities that can be detected, yields considerably enhanced staining intensities, and is compatible with using reduced amounts of these expensive reagents.
Kommentaar op Jakobus in Afrikaans
Authors: Jordaan Gert J.C.
Published: December 2014

No abstract available.
Exposure to ACGME Core Competencies through Mentored Basic Science Research: A Pilot Analysis
Authors: Wisco Jonathan J. , Thakur Sarika , Stark M. Elena
Published: December 2014

Since 1998, the Short-Term Training Program (STTP) at the David Geffen School of Medicine at the University of California, Los Angeles has nearly tripled (from 30 to 89) in the number of first-year undergraduate medical students participants. STTP supports mentored research projects in the areas of basic sciences, clinical sciences, medical education, and public health (local and international). Although projects can be very specific in scope, the overall experience in STTP exposes students to some, if not all, of the Accreditation Council for Graduate Medical Education (ACGME) six core competencies–-Patient Care, Medical Knowledge, Practice-based Learning and Improvement, Interpersonal and Communication Skills, Professionalism, and Systems-based Practice. Thus, STTP has been an important aspect of medical education to prepare our students for residency programs. We describe and analyze the STTP as a model system to introduce the ACGME core competencies at an early point in undergraduate medical education. We conclude with a call to provide more mentored anatomical sciences basic and clinically applied research opportunities.
Hydrogen peroxide in the marine boundary layer over the southern Atlantic during the OOMPH cruise in March 2007
Authors: Fischer H. , Pozzer A. , Schmitt T. , Jöckel P. , Klippel T. , Taraborrelli D. , Lelieveld J.
Published: December 2014

Abstract. In the OOMPH (Ocean Organics Modifying Particles in both Hemispheres) project a ship measurement cruise took place in the late austral summer from 1 to 23 March 2007. The French R/V Marion Dufresne sailed from Punta Arenas, Chile (70.85° W, 53.12° S) to La Reunion island (55.36° E, 21.06° S) across the southern Atlantic Ocean. In-situ measurements of hydrogen peroxide, methylhydroperoxide and ozone were performed and are compared to simulations with the atmospheric chemistry global circulation model EMAC. The model generally reproduces the measured trace gas levels, but underestimates hydrogen peroxide mixing ratios at high wind speeds, indicating too strong dry deposition to the ocean surface. An interesting feature during the cruise is a strong increase of hydrogen peroxide, methylhydroperoxide and ozone shortly after midnight off the west coast of Africa due to an increase in the boundary layer height, leading to downward transport from the free troposphere, which is realistically reproduced by the model.
Constrained two-stream algorithm for calculating aerosol light absorption coefficient from the Particle Soot Absorption Photometer
Authors: Müller T. , Virkkula A. , Ogren J. A.
Published: December 2014

Abstract. We present a new correction scheme for filter-based absorption photometers based on a constrained two-stream (CTS) radiative transfer model and experimental calibrations. The two-stream model was initialized using experimentally accessible optical parameters of the filter. Experimental calibrations were taken from the literature and from dedicated experiments for the present manuscript. Uncertainties in the model and calibration experiments are discussed and uncertainties for retrieval of absorption coefficients are derived. For single-scattering albedos lower than 0.8, the new CTS method and also other correction schemes suffer from the uncertainty in calibration experiments, with an uncertainty of about 20% in the absorption coefficient. For high single-scattering albedos, the CTS correction significantly reduces errors. At a single-scattering albedo of about 0.98 the error can be reduced to 30%, whereas errors using the Bond correction (Bond et al., 1999) are up to 100%. The correction scheme was tested using data from an independent experiment. The tests confirm the modeled performance of the correction scheme when comparing the CTS method to other established correction methods.
CHAMP climate data based on the inversion of monthly average bending angles
Authors: Danzer J. , Gleisner H. , Healy S. B.
Published: December 2014

Abstract. Global Navigation Satellite System Radio Occultation (GNSS-RO) refractivity climatologies for the stratosphere can be obtained from the Abel inversion of monthly average bending-angle profiles. The averaging of large numbers of profiles suppresses random noise and this, in combination with simple exponential extrapolation above an altitude of 80 km, circumvents the need for a "statistical optimization" step in the processing. Using data from the US–Taiwanese COSMIC mission, which provides ~1500–2000 occultations per day, it has been shown that this average-profile inversion (API) technique provides a robust method for generating stratospheric refractivity climatologies. Prior to the launch of COSMIC in mid-2006, the data records rely on data from the CHAMP (CHAllenging Mini-satellite Payload) mission. In order to exploit the full range of available RO data, the usage of CHAMP data is also required. CHAMP only provided ~200 profiles per day, and the measurements were noisier than COSMIC. As a consequence, the main research question in this study was to see if the average bending-angle approach is also applicable to CHAMP data. Different methods for the suppression of random noise – statistical and through data quality prescreening – were tested. The API retrievals were compared with the more conventional approach of averaging individual refractivity profiles, produced with the implementation of statistical optimization used in the EUMETSAT (European Organisation for the Exploitation of Meteorological Satellites) Radio Occultation Meteorology Satellite Application Facility (ROM SAF) operational processing. In this study it is demonstrated that the API retrieval technique works well for CHAMP data, enabling the generation of long-term stratospheric RO climate data records from August 2001 and onward. The resulting CHAMP refractivity climatologies are found to be practically identical to the standard retrieval at the DMI (Danish Meteorological Institute) below altitudes of 35 km. Between 35 and 50 km, the differences between the two retrieval methods started to increase, showing largest differences at high latitudes and high altitudes. Furthermore, in the winter hemisphere high-latitude region, the biases relative to ECMWF (European Centre for Medium-range Weather Forecasts) were generally smaller for the new approach than for the standard retrieval.
Level 2 processing for the imaging Fourier transform spectrometer GLORIA: derivation and validation of temperature and trace gas volume mixing ratios from calibrated dynamics mode spectra
Authors: Ungermann J. , Blank J. , Dick M. , Ebersoldt A. , Friedl-Vallon F. , Giez A. , Guggenmoser T. , Höpfner M. , Jurkat T. , Kaufmann M. , Kaufmann S. , Kleinert A. , Krämer M. , Latzko T. , Oelhaf H. , Olchewski F. , Preusse P. , Rolf C. , Schillings J. , Suminska-Ebersoldt O. , Tan V. , Thomas N. , Voigt C. , Zahn A. , Zöger M. , Riese M.
Published: December 2014

Abstract. The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) is an airborne infrared limb-imager combining a two-dimensional infrared detector with a Fourier transform spectrometer. It was operated aboard the new German Gulfstream G550 research aircraft HALO during the Transport And Composition in the upper Troposphere/lowermost Stratosphere (TACTS) and Earth System Model Validation (ESMVAL) campaigns in summer 2012. This paper describes the retrieval of temperature and trace gas (H2O, O3, HNO3) volume mixing ratios from GLORIA dynamics mode spectra. 26 integrated spectral windows are employed in a joint fit to retrieve seven targets using consecutively a fast and an accurate tabulated radiative transfer model. Typical diagnostic quantities are provided including effects of uncertainties in the calibration and horizontal resolution along the line-of-sight. Simultaneous in-situ observations by the BAsic HALO Measurement And Sensor System (BAHAMAS), the Fast In-Situ Stratospheric Hygrometer (FISH), FAIRO, and the Atmospheric chemical Ionization Mass Spectrometer (AIMS) allow a validation of retrieved values for three flights in the upper troposphere/lowermost stratosphere region spanning polar and sub-tropical latitudes. A high correlation is achieved between the remote sensing and the in-situ trace gas data, and discrepancies can to a large fraction be attributed to differences in the probed air masses caused by different sampling characteristics of the instruments. This 1-D processing of GLORIA dynamics mode spectra provides the basis for future tomographic inversions from circular and linear flight paths to better understand selected dynamical processes of the upper troposphere and lowermost stratosphere.
Pasture degradation modifies the water and carbon cycles of the Tibetan highlands
Authors: Babel W. , Biermann T. , Coners H. , Falge E. , Seeber E. , Ingrisch J. , Schleuß P.-M. , Gerken T. , Leonbacher J. , Leipold T. , Willinghöfer S. , Schützenmeister K. , Shibistova O. , Becker L. , Hafner S. , Spielvogel S. , Li X. , Xu X. , Sun Y. , Zhang L. , Yang Y. , Ma Y. , Wesche K. , Graf H.-F. , Leuschner C. , Guggenberger G. , Kuzyakov Y. , Miehe G. , Foken T.
Published: December 2014

Abstract. The Tibetan Plateau has a significant role with regard to atmospheric circulation and the monsoon in particular. Changes between a closed plant cover and open bare soil are one of the striking effects of land use degradation observed with unsustainable range management or climate change, but experiments investigating changes of surface properties and processes together with atmospheric feedbacks are rare and have not been undertaken in the world's two largest alpine ecosystems, the alpine steppe and the Kobresia pygmaea pastures of the Tibetan Plateau. We connected measurements of micro-lysimeter, chamber, 13C labelling, and eddy covariance and combined the observations with land surface and atmospheric models, adapted to the highland conditions. This allowed us to analyse how three degradation stages affect the water and carbon cycle of pastures on the landscape scale within the core region of the Kobresia pygmaea ecosystem. The study revealed that increasing degradation of the Kobresia turf affects carbon allocation and strongly reduces the carbon uptake, compromising the function of Kobresia pastures as a carbon sink. Pasture degradation leads to a shift from transpiration to evaporation while a change in the sum of evapotranspiration over a longer period cannot be confirmed. The results show an earlier onset of convection and cloud generation, likely triggered by a shift in evapotranspiration timing when dominated by evaporation. Consequently, precipitation starts earlier and clouds decrease the incoming solar radiation. In summary, the changes in surface properties by pasture degradation found on the highland have a significant influence on larger scales.
Predicting the denitrification capacity of sandy aquifers from in situ measurements using push-pull 15N tracer tests
Authors: Eschenbach W. , Well R. , Walther W.
Published: December 2014

Abstract. Knowledge about the spatial variability of in situ denitrification rates (Dr(in situ)) and their relation to the denitrification capacity in nitrate-contaminated aquifers is crucial to predict the development of groundwater quality. Therefore, 28 push-pull 15N tracer tests for the measurement of in situ denitrification rates were conducted in two sandy Pleistocene aquifers in Northern Germany. The 15N analysis of denitrification derived 15N labelled N2 and N2O dissolved in water samples collected during the push-pull 15N tracer tests was performed by isotope ratio mass spectrometry (IRMS) in the lab and additionally for some tracer tests online in the field with a quadrupole membrane inlet mass spectrometer (MIMS), in order to test the feasibility of on-site real-time 15N analysis. Aquifer material from the same locations and depths as the push-pull injection points was incubated and the initial and cumulative denitrification after one year of incubation (Dcum(365)) as well as the stock of reduced compounds (SRC) was compared with in situ measurements of denitrification. This was done to derive transfer functions suitable to predict Dcum(365) and SRC from Dr(in situ). Dr(in situ) ranged from 0 to 51.5 μg N kg−1 d−1. Denitrification rates derived from on-site isotope analysis using membrane-inlet mass spectrometry satisfactorily coincided with laboratory analysis by conventional isotope ratio mass spectrometry, thus proving the feasibility of in situ analysis. Dr(in situ) was significantly higher in the sulphidic zone of both aquifers compared to the zone of non-sulphidic aquifer material. Overall, regressions between the Dcum(365) and SRC of the tested aquifer material with Dr(in situ) exhibited only a modest linear correlation for the full data set. But the predictability of Dcum(365) and SRC from Dr(in situ) data clearly increased for aquifer samples from the zone of NO3−-bearing groundwater. In the NO3−-free aquifer zone a lag phase of denitrification after NO3− injections was observed, which confounded the relationship between reactive compounds and in situ denitrification activity. This finding was attributed to adaptation processes in the microbial community after NO3− injections. Exemplarily, it was demonstrated that the microbial community in the NO3−-free zone close below the NO3−-bearing zone can be adapted to denitrification by amending wells with NO3−-injections for an extended period. In situ denitrification rates were 30 to 65% higher after pre-conditioning with NO3−. Results from this study suggest that such pre-conditioning is crucial for the measurement of Dr(in situ) in deeper aquifer material from the NO3−-free groundwater zone and thus for the prediction of Dcum(365) and SRC from Dr(in situ).
Technical Note: Silica stable isotopes and silicification in a carnivorous sponge \\textit{Asbestopluma} sp.
Authors: Hendry K. R. , Swann G. E. A. , Leng M. J. , Sloane H. J. , Goodwin C. , Berman J. , Maldonado M.
Published: December 2014

Abstract. The stable isotope composition of benthic sponge spicule silica is a potential source of palaeoceanographic information about past deep seawater chemistry. The silicon isotopic composition of spicules has been shown to relate to the silicic acid concentration of ambient water, although existing calibrations do exhibit a degree of scatter in the relationship. Less is known about how the oxygen isotope composition of sponge spicule silica relates to environmental conditions during growth. Here, we investigate the biological vital effects on silica silicon and oxygen isotope composition in a carnivorous sponge, Asbestopluma sp., from the Southern Ocean. We find significant variations in silicon and oxygen isotopic composition within the specimen that appear related to unusual spicule silicification. The largest variation in both isotope systems was associated to the differential distribution of an unconventional, hypersilicified spicule type (desma) along the sponge body. The absence of an internal canal in the desmas suggests an unconventional silicification pattern leading to an unusually heavy isotopic signature. Additional internal variability derives from a systematic offset between the peripheral skeleton of the body having systematically a higher isotopic composition than the internal skeleton. A simplified silicon isotope fractionation model, in which desmas were excluded, suggests that the lack of a system for seawater pumping in carnivorous sponges favours a low replenishment of dissolved silicon within the internal tissues, causing kinetic fractionation during silicification that impacts the isotopic signature of the internal skeleton. Analysis of multiple spicules should be carried out to "average out" any artefacts in order to produce more robust downcore measurements.
Testing gridded land precipitation data and precipitation and runoff reanalyses (1982–2010) between 45° S and 45° N with Normalized Difference Vegetation Index data
Authors: Los S. O.
Published: December 2014

Abstract. The realistic simulation of key components of the land-surface hydrological cycle – precipitation, runoff, evaporation and transpiration – in general circulation models of the atmosphere is crucial to assess adverse weather impacts on environment and society. Here, gridded precipitation data from observations and precipitation and runoff fields from reanalyses were tested with satellite-derived global vegetation index data for 1982–2010 and latitudes between 45° S and 45° N. Data were obtained from the Climate Research Unit (CRU), the Global Precipitation Climatology Project (GPCP) and Tropical Rainfall Monitoring Mission (TRMM; analysed for 1998–2010 only) and (precipitation and runoff) reanalyses were obtained from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR), the European Centre for Medium-Range Weather Forecasts (ECMWF) and the NASA Global Modelling and Assimilation Office (GMAO). Annual land-surface precipitation was converted to annual potential vegetation net primary productivity (NPP) and was compared to mean annual Normalized Difference Vegetation Index data measured by the Advanced Very High Resolution Radiometer (1982–1999) and MODIS (2001–2010). The effect of spatial resolution on the agreement between NPP and NDVI was investigated as well. The CRU and TRMM derived NPP agreed most closely with the NDVI data. The GPCP data showed weaker spatial agreement, largely because of their lower spatial resolution, but similar temporal agreement. MERRA Land and ERA Interim precipitation reanalyses showed similar spatial agreement as the GPCP data and good temporal agreement in semi-arid regions of the Americas, Asia, Australia and southern Africa. The NCEP/NCAR reanalysis showed the lowest spatial agreement which could only in part be explained by its lower spatial resolution. No reanalysis showed realistic interannual precipitation variations for northern tropical Africa. Inclusion of runoff in the NPP prediction resulted only in (marginally) better agreement for the MERRA Land reanalysis and worse agreement for the NCEP/NCAR and ERA Interim reanalyses.
Study of the seismicity temporal variation for the current seismic hazard evaluation in Val d'Agri, Italy
Authors: Baskoutas I. , D'Alessandro A.
Published: December 2014

Abstract. This study examines the temporal variation of the seismicity in the Val d'Agri (southern Italy) and adjacent areas, for the current seismic hazard evaluation. The temporal variation of the seismicity is expressed as time series of the number of earthquakes, b value of Gutenberg–Richter relationship or b value of the frequency–magnitude distribution and the seismic energy released in the form of logE2/3. The analysis was performed by means of a new research tool that includes visualizing techniques, which helps the interactive exploration and the interpretation of temporal variation changes. The obtained time series show a precursory seismicity pattern, characterized by low and high probability periods, which preceded earthquakes of magnitude M ≥ 4.0. The 75% of the examined cases were successfully correlated with a change in seismicity pattern. The average duration of the low and the high probability periods is 10.6 and 13.8 months respectively. These results indicate that the seismicity temporal variation monitoring in a given area and the recognition of the low and high probability periods can contribute to the evaluation, in regular monthly intervals, of current seismic hazard status.
Linking local wildfire dynamics to pyroCb development
Authors: McRae R. H. D. , Sharples J. J. , Fromm M.
Published: December 2014

Abstract. Extreme wildfires are global phenomena that consistently result in loss of life and property, and further impact the cultural, economic and political stability of communities. In their most extreme form they cause widespread devastation of environmental assets and are capable of impacting the upper troposphere–lower stratosphere through the formation of a thunderstorm within the plume. Such fires are now often observed by a range of remote sensing technologies, which together allow a greater understanding of a fire's complex dynamics. This paper considers one such fire that burnt in the Blue Mountains region of Australia in late-November 2006, that is known to have generated significant pyrocumulonimbus clouds in a series of blow-up events. Observations of this fire are analysed in detail to investigate the localised processes contributing to extreme fire development. In particular, it has been possible to demonstrate for the first time that the most severe instances of pyroconvection were driven by, and not just associated with, extreme local fire dynamics, especially the fire channelling phenomenon, which arises due to an interaction between an active fire, local terrain attributes and critical fire weather, and causes the fire to rapidly transition from a frontal to an areal burning pattern. The impacts of local variations in fire weather and of the atmospheric profile are also discussed, and the ability to predict extreme fire development with state-of-the-art tools is explored.
Tunable diode laser measurements of hydrothermal/volcanic CO2 and implications for the global CO2 budget
Authors: Pedone M. , Aiuppa A. , Giudice G. , Grassa F. , Francofonte V. , Bergsson B. , Ilyinskaya E.
Published: December 2014

Abstract. Quantifying the CO2 flux sustained by low-temperature fumarolic fields in hydrothermal/volcanic environments has remained a challenge, to date. Here, we explored the potential of a commercial infrared tunable laser unit for quantifying such fumarolic volcanic/hydrothermal CO2 fluxes. Our field tests were conducted between April 2013 and March 2014 at Nea Kameni (Santorini, Greece), Hekla and Krýsuvík (Iceland) and Vulcano (Aeolian Islands, Italy). At these sites, the tunable laser was used to measure the path-integrated CO2 mixing ratios along cross sections of the fumaroles' atmospheric plumes. By using a tomographic post-processing routine, we then obtained, for each manifestation, the contour maps of CO2 mixing ratios in the plumes and, from their integration, the CO2 fluxes. The calculated CO2 fluxes range from low (5.7 ± 0.9 t d−1; Krýsuvík) to moderate (524 ± 108 t d−1; La Fossa crater, Vulcano). Overall, we suggest that the cumulative CO2 contribution from weakly degassing volcanoes in the hydrothermal stage of activity may be significant at the global scale.
The economics of soil C sequestration
Authors: Alexander P. , Paustian K. , Smith P. , Moran D.
Published: December 2014

Abstract. Carbon is a critical component of soil vitality and of our ability to produce food. Carbon sequestered in soils also provides a further regulating ecosystem service, valued as the avoided damage from global climate change. We consider the demand and supply attributes that underpin and constrain the emergence of a market value for this vital global ecosystem service: markets being what economists regard as the most efficient institutions for allocating scarce resources to the supply and consumption of valuable goods. This paper considers how a potentially large global supply of soil carbon sequestration is reduced by economic and behavioural constraints that impinge on the emergence of markets, and alternative public policies that can efficiently transact demand for the service from private and public sector agents. In essence this is a case of significant market failure. In the design of alternative policy options we consider whether soil carbon mitigation is actually cost-effective relative to other measures in agriculture and elsewhere in the economy, and the nature of behavioural incentives that hinder policy options. We suggest that reducing cost and uncertainties of mitigation through soil-based measures is crucial for improving uptake. Monitoring and auditing processes will also be required to eventually facilitate wide-scale adoption of these measures.
Post-LIA glacier changes along a latitudinal transect in the Central Italian Alps
Authors: Scotti R. , Brardinoni F. , Crosta G. B.
Published: December 2014

Abstract. The variability of glacier response to atmospheric temperature rise in different topo-climatic settings is still a matter of debate. To address this question in the Central Italian Alps, we compile a post-LIA (Little Ice Age) multitemporal glacier inventory (1860–1954–1990–2003–2007) along a latitudinal transect that originates north of the continental divide in the Livigno Mountains and extends south through the Disgrazia and Orobie ranges, encompassing continental-to-maritime climatic settings. In these sub-regions, we examine the area change of 111 glaciers. Overall, the total glacierized area has declined from 34.1 to 10.1 km2, with a substantial increase in the number of small glaciers due to fragmentation. The average annual decrease (AAD) in glacier area has risen by about 1 order of magnitude from 1860–1990 (Livigno: 0.45; Orobie: 0.42; and Disgrazia: 0.39 % a−1) to 1990–2007 (Livigno: 3.08; Orobie: 2.44; and Disgrazia: 2.27 % a−1). This ranking changes when considering glaciers smaller than 0.5 km2 only (i.e., we remove the confounding caused by large glaciers in Disgrazia), so that post-1990 AAD follows the latitudinal gradient and Orobie glaciers stand out (Livigno: 4.07; Disgrazia: 3.57; and Orobie: 2.47 % a−1). More recent (2007–2013) field-based mass balances in three selected small glaciers confirm post-1990 trends showing the consistently highest retreat in continental Livigno and minimal area loss in maritime Orobie, with Disgrazia displaying transitional behavior. We argue that the recent resilience of glaciers in Orobie is a consequence of their decoupling from synoptic atmospheric temperature trends, a decoupling that arises from the combination of local topographic configuration (i.e., deep, north-facing cirques) and high winter precipitation, which ensures high snow-avalanche supply, as well as high summer shading and sheltering. Our hypothesis is further supported by the lack of correlations between glacier change and glacier attributes in Orobie, as well as by the higher variability in ELA,sub>0 positioning, post-LIA glacier change, and interannual mass balances, as we move southward along the transect.
Sequential Spontaneous Resolution of Acute Syphilitic Posterior Placoid Chorioretinitis
Authors: Aranda Sergio , Amer Radgonde
Published: December 2014

Purpose

Acute syphilitic posterior placoid chorioretinitis (ASPPC) is a distinctive manifestation of ocular syphilis characterized by the development of a placoid macular deposit in the outer retina. Fundus autofluorescence descriptions suggest it may result from subretinal deposition of retinal pigment epithelium (RPE)–photoreceptor complex material and incomplete phagocytosis of outer segments. A 14-day therapy with systemic penicillin is essential for prompt control of the infection and to limit substantial retinal damage and irreversible visual loss. We report on the spontaneous sequential resolution of ASPPC in a patient with HIV coinfection.

Methods

Descriptive case report.

Results

A 55-year-old man presented with profound decrease in vision in his left eye secondary to ASPPC. Nine days later, ASPPC resolved, and a similar process developed in the right eye. Four years earlier, HIV infection had been diagnosed, and the patient was maintained on antiretroviral therapy with good immune recovery (CD4+ T-cell count 204 cells/µL). Spontaneous resolution ensued in the right eye and vision was restored.

Conclusions

Ocular immune privilege probably contributed to the spontaneous resolution of ASPPC in this patient, who experienced immune recovery following antiretroviral therapy. The RPE immunologic characteristics likely contained the infectious/inflammatory infiltrate in this patient and prevented extension to inner retina and optic disc. Despite the uniqueness of the present case and the spontaneous resolution and excellent visual outcome, it remains essential to promptly manage patients with ocular syphilis because of the possible sight-threatening complications and to prevent potentially fatal disease.
Modified Scleral Suture Fixation Technique for Foldable IOL with Fenestrations in the Proximal Part of the Haptics
Authors: Kaluzny Bartlomiej J. , Laudencka Adriana , Malukiewicz Grażyna
Published: December 2014

Purpose

To present a modified surgical technique for scleral suture fixation of a new foldable intraocular lens (IOL) design with fenestrations in the proximal part of the haptics.

Methods

An experimental model of a double continuous-loop 4-point scleral suture fixation of IOL with fenestrations in the proximal part of the haptics showed that with conventional techniques, the lens is located in a horizontal plane 90° to the expected iris plane. To achieve proper IOL positioning, we modified the technique so as to perform 2 needle passes through the sclera for each haptic in the same meridian, resulting in the external part of the suture being radial to the limbus. The technique was performed in 14 eyes. Mean follow-up time was 9.8 months.

Results

In all cases, the lens was successfully implanted through clear corneal tunnel incision and the scleral fixation, as mentioned above, was performed with the use of Hoffman scleral pockets. Good centration of the IOLs without signs of tilt was achieved.

Conclusions

It is possible to decrease the risk of tilt of the IOL with fenestrations in the proximal part of the haptics by modifying the technique so that the 2 needle passes through the sclera for each haptic are done in the same meridian, resulting in a layout of the external part of the suture being radial to the limbus.