bluuebunny/crossref_metadata_2025 huggingface dataset:
Artivism and NGO: Relationship between image and 'engagement' in Instagram
Authors: Carrasco-Polaino Rafael , Villar-Cirujano Ernesto , Martín-Cárdaba Miguel-Ángel
Published: July 2018

Due to the increasing importance of acquiring technological tools in communication strategies, and while taking into account that non-Governmental Organizations (NGO) use Instagram as a potential artivist tool to disseminate their initiatives and needs, the present article aims to investigate the form and content of photographs published in the social website Instagram during 2017 by the 20 most relevant NGOs at the international level. Specifically, we study the choice of formal elements, such as the design and editing, the intended purpose and feeling of the message transmitted in the photographs, as well as the type of actor or actors of the images (including their role, number, gesture, sex and age). In addition, we study the use and the engagement generated by children’s images. Content analysis, non-parametric statistical analysis with Chi-square test and variance analysis (ANOVA) are used as methodologies. The results of the study show how prototypical images used by NGOs (young children enjoying the benefits of aid with positive appearance and gestures) present content and formats that do not correspond to the type of image that generates more engagement from the target audience.

Debido a la creciente importancia que adquieren las herramientas tecnológicas en las estrategias de comunicación, y teniendo en cuenta que las Organizaciones no Gubernamentales (ONG) utilizan Instagram como una herramienta con potencial artivista para difundir sus iniciativas y necesidades, el presente artículo tiene como objetivo investigar la forma y el contenido de las fotografías publicadas en esta red social a lo largo del año 2017 por las 20 ONG más relevantes a nivel internacional. En concreto, se estudia la elección de elementos formales, como el tipo de plano o la edición, la finalidad del mensaje que se quiere trasladar o el sentimiento transmitido en las fotografías, así como el tipo de actor o actores protagonistas de las imágenes (rol, número, gesto, sexo y edad). Además, se estudia el «engagement» generado por las fotografías y el uso que se hace en ellas de la figura del niño. Se utiliza como metodología el análisis de contenido, el análisis estadístico no paramétrico con prueba de Chi-cuadrado y el análisis de varianzas (ANOVA). Los resultados del estudio muestran cómo la imagen prototípica que usan las ONG -receptor de la ayuda menor de edad, disfrutando de los beneficios de esta ayuda y con gesto positivo- presenta un contenido y un formato que no se corresponden con el tipo de imagen que más «engagement» genera entre los usuarios y seguidores.
Towards understanding young children’s digital lives in China and Australia
Authors: Gou He , Dezuanni Michael
Published: July 2018

This article develops insights and generates new lines of inquiry into young children’s digital lives in China and Australia. It brings to dialogue findings from a national study of young children's digital media use in urban settings in China with findings from studies in Australia. This is not presented as a direct comparison, but rather as an opportunity to shed light on children’s digital lives in two countries and to account for the impact of context in relatively different social and cultural circumstances. The article outlines findings from a study of 1,171 preschool-aged children (3 to 7-year-olds) in six provinces in China, including the frequency of their use of television, early education digital devices, computers, tablet computers and smartphones, music players, e-readers and games consoles. It also focuses on various activities such as watching cartoons, using educational apps, playing games and participating in video chat. Methods included a multistage sampling process, random selection of kindergartens, a weighted sampling process, the generation of descriptive data and the use of linear regression analysis, and a chi-square test. The study demonstrates the significance of a range of factors that influence the amount of time spent with digital media. The contrast with Australian studies produces new insights and generates new research questions.

Este artículo desarrolla ideas y genera nuevas líneas de investigación sobre las vidas digitales de los niños en China y Australia, en discusión con las conclusiones de estudios nacionales sobre el uso de los medios digitales por parte de los niños en entornos urbanos en China y Australia. El trabajo gira en torno al mundo digital de los niños en los dos países, analizando el impacto del contexto en ámbitos sociales y culturales significativamente diferentes. El estudio abarca una muestra de 1.171 niños de 3 a 7 años, de seis provincias de China, presentando la frecuencia de uso de televisión, dispositivos digitales en la educación temprana, ordenadores, tabletas y teléfonos inteligentes, reproductores de música, libros electrónicos y videoconsolas. También se enfoca en diversas actividades como ver dibujos animados, usar aplicaciones educativas, jugar a videojuegos y participar en videollamadas. Los métodos incluyeron un proceso de muestreo multietapa, con selección aleatoria de jardines infantiles, un proceso de muestreo ponderado, la generación de datos descriptivos y el uso del análisis de regresión lineal, y una prueba de chi-cuadrado. El estudio demuestra la importancia del rango de factores que influyen en la cantidad de tiempo que pasan con los medios digitales. El contraste con los estudios australianos produce nuevos conocimientos y genera nuevas preguntas de investigación.
University training on entrepreneurship in communication and journalism business projects
Authors: Aceituno-Aceituno Pedro , Casero-Ripollés Andreu , Escudero-Garzás José-Joaquín , Bousoño-Calzón Carlos
Published: July 2018

The current scenario of crisis and change has prompted the idea of entrepreneurship as a way to develop new media business models that can be promoted by university training. In this study, we aim to assess the effects of such training. A qualitative study was conducted using in-depth interviews of Spanish journalism and communication entrepreneurs who have undergone university training in business creation and management. Our results show the positive effects of this training on entrepreneurship both in general and on specific aspects of entrepreneurial projects such as organization, business plan/model, marketing, innovation, social aspects and quality of life. Different patterns between the effects of university training on new initiatives and advanced projects were also observed. In this respect, the training supported the creation of new businesses and the development of existing ones. Finally, the suggestions for improving training and the limitations to entrepreneurship have revealed the importance of providing this type of education with a more practical, up-to-date approach that is interconnected with the business and university world. Therefore, examples of this work can be of vital importance in opening up new opportunities for sector development to enable future generations of journalists to fulfill their important social function.

El escenario actual de crisis y cambios ha llevado a pensar en el emprendimiento como una nueva vía para el desarrollo de nuevos modelos de negocio en los medios de comunicación, que puede ser fomentado por la formación universitaria. El objetivo de este estudio es valorar los efectos de dicha formación, para lo que se ha desarrollado una investigación cualitativa basada en entrevistas en profundidad entre emprendedores españoles de periodismo y comunicación que han recibido formación universitaria en creación y gestión de empresas. Los resultados muestran el efecto positivo de esta formación sobre el emprendimiento en general y también sobre aspectos concretos de los proyectos empresariales: organización, plan/modelo de negocio, marketing, innovación, aspectos sociales y calidad de vida. También, se han observado diferentes pautas entre los efectos obtenidos para las nuevas iniciativas y para los proyectos avanzados. En este sentido, la formación ha apoyado la creación de los nuevos negocios. Por último, las sugerencias para mejorar la formación y las limitaciones al emprendimiento aportadas han revelado la importancia de dotar a este tipo de educación de mayor carácter práctico, actualizado e interconectado con el mundo empresarial y universitario. Por ello, los ejemplos de este trabajo pueden resultar de vital importancia para abrir nuevas oportunidades al desarrollo del sector que permitan a las futuras generaciones de periodistas cumplir su importante función social.
Diffusion and Point Defects in Elemental Semiconductors
Authors: Mehrer Helmut
Published: July 2018

Elemental semiconductors play an important role in high-technology equipment used in industry and everyday life. The first transistors were made in the 1950ies of germanium. Later silicon took over because its electronic band-gap is larger. Nowadays, germanium is the base material mainly for γ-radiation detectors. Silicon is the most important semiconductor for the fabrication of solid-state electronic devices (memory chips, processors chips, ...) in computers, cellphones, smartphones. Silicon is also important for photovoltaic devices of energy production.Diffusion is a key process in the fabrication of semiconductor devices. This chapter deals with diffusion and point defects in silicon and germanium. It aims at making the reader familiar with the present understanding rather than painstakingly presenting all diffusion data available a good deal of which may be found in a data collection by Stolwijk and Bracht [1], in the author’s textbook [2], and in recent review papers by Bracht [3, 4]. We mainly review self-diffusion, diffusion of doping elements, oxygen diffusion, and diffusion modes of hybrid foreign elements in elemental semiconductors.Self-diffusion in elemental semiconductors is a very slow process compared to metals. One of the reasons is that the equilibrium concentrations of vacancies and self-interstitials are low. In contrast to metals, point defects in semiconductors exist in neutral and in charged states. The concentrations of charged point defects are therefore affected by doping [2 - 4].
Diffusion and Defect Phenomena in III-V Semiconductors and their Investigation by Transmission Electron Microscopy
Authors: Jäger Wolfgang
Published: July 2018

This article reviews the studies of diffusion and defect phenomena induced by high-concentration zinc diffusion in the single-crystal III-V compound semiconductors GaAs, GaP, GaSb and InP by methods of transmission electron microscopy and their consequences for numerical modelling of Zn (and Cd) diffusion concentration profiles. Zinc diffusion from the vapour phase into single-crystal wafers has been chosen as a model case for interstitial-substitutional dopant diffusion in these studies. The characteristics of the formation of diffusion-induced extended defects and of the temporal evolution of the defect microstructure correlate with the experimentally determined Zn profiles whose shapes depend on the chosen diffusion conditions. General phenomena observed for all semiconductors are the formation of dislocation loops, precipitates, voids, and dislocations and of Zn-rich precipitates in the diffusion regions. The formation of extended defects near the diffusion front can be explained as result of point defect supersaturations generated by interstitial-substitutional zinc exchange via the kick-out mechanism. The defects may act as sinks for dopants and as sources and sinks for point defects during the continuing diffusion process, thereby providing a path to establishing defect-mediated local point defect equilibria. The investigations established a consistent picture of the formation and temporal evolution of defects and the mechanisms of zinc diffusion in these semiconductors for diffusion conditions leading to high-concentration Zn concentrations. Based on these results, numerical modelling of anomalously shaped dopant concentration profiles leads to satisfactory quantitative results and yields information on type and charge states of the point defect species involved, also for near-surface Zn concentration profiles and the absence of extended defects.
The Structure, Microhardness and Wear Resistance of Coatings Obtained through Non-Vacuum Electron Beam Cladding of Chromium and Titanium Carbides on Low Carbon Steel
Authors: Krylova Tatyana A. , Ivanov Konstantin V. , Ovcharenko Vladimir E.
Published: July 2018

An interrelation between structural features, microhardness and wear resistance was studied in the coatings obtained by non-vacuum relativistic electron beam cladding of chromium and titanium carbides powder mixture on low carbon steel. Five coatings differing in the amount of the entered energy were investigated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), indentation tests and wear resistance measurements. It was found that the concentration of alloying elements both in solid solution and eutectic as well as the volume fraction of eutectic are the main structural characteristics which defines the microhardness of the coatings. The distribution of TiC phase plays a key role in the resistance to wear.
The Comparison of Thermal Insulation Materials for a Process Pipeline
Authors: Tretiakova Polina A. , Stepanov O.A. , Tretyakova T.V.
Published: July 2018

the article describes and compares thermal insulation materials used for heat insulation of a process pipeline transporting natural gas after its pressure reduction. The following thermal insulation materials are examined: mineral wool and cellular rubber substance. Linear thermal resistance has been chosen as the essential property of the materials.
System for Centralised Collection, Recycling and Removal of Waste Pickling and Galvanic Solutions and Sludge
Authors: Merentsov N.A. , Bokhan S.A. , Lebedev V.N. , Persidskiy A.V. , Balashov V.A.
Published: July 2018

The article presents an approach to centralised collection, recycling and removal of waste pickling and galvanic solutions and sludge designed for small steel making plants and workshops having the described processes and using flow-through filter blocks.
The Development of Technology of Basalt Nanocomposite Coatings Detonation-Gas Spaying on the Disk («Target») Basis of Thin Layer Magnetron Spaying Equipment
Authors: Sitnikova T.A. , Zhukov E.B. , Golovina T.A. , Saprykina N.A. , Tesleva Elena P.
Published: July 2018

The chemical composition, structure and microhardness of detonation coatings based on mechanically activated mixture of basalt powder and TiAl have been studied. It has been shown that the application of mechanomixture with detonation method results in the formation of composite coating similar to the composition of starting mixture. It has high microhardness and temperature resistance that will increase the wear resistance of the parts coated with basalt at elevated temperatures.
Numerical Simulation of Thermal Processes in Welding with Pulsed Electrode Wire Feeding
Authors: Il’yaschenko D.P. , Berg Vladimir I. , Kryukov Artem B. , Saranchin А.A.
Published: July 2018

The use of computational methods allows us to significantly shorten the time required for researches and save welding and other consumables. In addition, the computational methods used in studies make it possible to demonstrate the obtained results with a high degree of accuracy. Computational methods are based on computer-aided mathematical modeling of welding processes. Mathematical modeling is applied specifically to develop models adequately describing various welding processes or interrelation between those processes. The article describes the model that demonstrates the distribution of temperature fields in butt joints during the arc welding with pulsed electrode wire feeding.
Elevated Troponin and Left Bundle Branch Block in the Setting of Suspected Septicemia and Demand Ischemia: To Treat or Not to Treat
Authors: Sharma Munish , Toor Rubinder , Khalighi Koroush
Published: July 2018

Elevated troponin and atypical chest pain in the setting of septicemia and Type II Non ST elevation myocardial infarction is frequently encountered. These cases are not necessarily scheduled for emergent cardiac catheterization. High index of clinical suspicion and continuous in-patient cardiac monitoring with serial trending of cardiac enzymes are important in such cases. Subsequent sudden development of electrocardiogram changes requires prompt investigation with emergent coronary catheterization. These types of cases may be missed especially in females who present with atypical chest pain and in patients with Left bundle branch block.
Clinical development of RET inhibitors in RET-rearranged non-small cell lung cancer: Update
Authors: Mendoza Luis
Published: July 2018

Precision oncology is now the evidence-based standard of care for the management of many advanced non-small cell lung cancers (NSCLC). Notably, new molecular profiling technologies have permitted dynamic growth in the identification of actionable driver oncogenes including RET rearrangements. RET oncogenes cannot be adequately detected by immunohistochemistry, although fluorescence in situ hybridization, reverse transcriptase polymerase chain reaction and next-generation sequencing are complementary diagnostic tools. In the clinical setting, the benefit of the most developed RET inhibitors, i.e., cabozantinb, vandetanib and lenvatinb, in terms of response and median progressionfree survival has been demonstrated. The absence of striking clinical results of RET inhibitors underscores the clear need for development of more selective and potent RET inhibitors. This paper reviews the clinical data available on RET inhibitors in RET-associated NSCLC.
Bilastine
Authors: Gandhi Jeet , Godse Kiran , Godse Gauri
Published: July 2018

Bilastine is a new second generation H1-antihistamine approved for the symptomatic treatment of allergic rhinitis (AR) and chronic urticaria (CU) in patients older than 12 years of age. AR and urticaria are very common clinical conditions that represent one of the most frequent reasons for a patient to visit their general practitioner or allergist or dermatologist. Bilastine, with its efficacy and safety profile epitomizes the evolution of research on antihistamines.
Role of Omalizumab in Refractory Chronic Spontaneous Urticaria
Authors: Singh Gautam Kumar , Chatterjee Manas , Verma Rajesh
Published: July 2018

Background:

Multiple evidence have shown that omalizumab, a subcutaneous (SC) anti-IgE monoclonal antibody, is highly effective for the treatment of chronic spontaneous urticaria (CSU).

Objective:

The objective is to evaluate the safety and efficacy of omalizumab administered 300 mg SC 1st month followed by 150 mg every month for another 5 months in cases of refractory CSU in a routine clinical setting.

Materials and Methods:

This was open-label, prospective, pilot study to know the efficacy and safety profile of omalizumab administered 300 mg SC first 1st month followed by 150 mg every month for another five 5 months in refractory CSU. The study was conducted at tertiary center in routine clinical setting. The primary efficacy evaluation was a change in Urticaria Activity Score-7 (UAS-7) and Urticaria Control Test (UCT) from baseline.

Results:

A total of 13 patients (7 females and 6 males) were enrolled in the study with the mean age of 35 years, having CSU from the mean duration of 3.15 years. Mean UAS-7 of patients decreased from 31.62 at baseline to 6.85 after the first dose of omalizumab treatment. This further reduced to 2.31 after 6 months (P = 0.001). Mean UCT increased from 4.46 at baseline to 13.92 after 1 month and further increased to 14.85 after 6 months (P = 0.001). A total of 11 patients (84.6%) achieved complete remission.

Conclusion:

Injection omalizumab is safe and highly effective therapy for refractory CSU in the routine clinical setting. It can be made cost effective without compromising the efficacy in resource-poor country of Indian subcontinent if barring first dose other can be halved of recommended dose. However, small number of patients, uncontrolled study and lack of long-term follow-up data are the limitations of the study.
Oxidative stress as a possible pathogenic cofactor of post-menopausal osteoporosis
Authors: Bonaccorsi Gloria , Piva Isabella , Greco Pantaleo , Cervellati Carlo
Published: July 2018

Post-menopausal osteoporosis (PO) is one of the major health issues associated with menopause-related oestrogen withdrawal. Despite the intense research and the relevant progress achieved in the last two decades, the pathogenic mechanism underlying PO is still poorly understood. As a consequence of this gap in the knowledge, such disorder and the related complications are still difficult to be effectively prevented. A wealth of experimental and epidemiological/clinical evidence suggests that the endocrine change associated to menopausal transition might lead to a derangement of redox homeostasis, that is, the prelude to the health-threaten condition of oxidative stress (OxS). In turn, this (bio)chemical stress has been widely hypothesized to contribute, most likely in synergy with inflammation, to the development of menopause-related diseases, including PO. The main aim of this review is to discuss the current literature evidence on the association between post-menopausal oestrogen withdrawal, OxS and PO. It is also aimed to provide a critical overview of the most significant epidemiological studies on the effects of dietary antioxidants on bone health and to devise a strategy to overcome the limitations emerged and controversial results.
Fabrication of WC/Co composite powder from oxide of WC/Co hardmetal scrap by carbothermal reduction process
Authors: Lee Gil-Geun , Lim Young Soo
Published: July 2018

This study focuses on the fabrication of a WC/Co composite powder from the oxide of WC/Co hardmetal scrap using solid carbon in a hydrogen gas atmosphere for the recycling of WC/Co hardmetal. Mixed powders are manufactured by mechanically milling the oxide powder of WC-13 wt% Co hardmetal scrap and carbon black with varying powder/ball weight ratios. The oxide powder of WC-13 wt% Co hardmetal scrap consists of WO3 and CoWO4. The mixed powder mechanically milled at a lower powder/ball weight ratio (high mechanical milling energy) has a more rapid carbothermal reduction reaction in the formation of WC and Co phases compared with that mechanically milled at a higher powder/ball weight ratio (lower mechanical milling energy). The WC/Co composite powder is fabricated at 900°C for 6 h from the oxide of WC/Co hardmetal scrap using solid carbon in a hydrogen gas atmosphere. The fabricated WC/Co composite powder has a particle size of approximately 0.25-0.5 μm.
Photocatalytic activity of rutile TiO2 powders coupled with anatase TiO2 nanoparticles using surfactant
Authors: Byun Jong Min , Park Chun Woong , Kim Young In , Kim Young Do
Published: July 2018

The coupling of two semiconducting materials is an efficient method to improve photocatalytic activity via the suppression of recombination of electron-hole pairs. In particular, the coupling between two different phases of TiO2, i.e., anatase and rutile, is particularly attractive for photocatalytic activity improvement of rutile TiO2 because these coupled TiO2 powders can retain the benefits of TiO2, one of the best photocatalysts. In this study, anatase TiO2 nanoparticles are synthesized and coupled on the surface of rutile TiO2 powders using a microemulsion method and heat treatment. Triton X-100, as a surfactant, is used to suppress the aggregation of anatase TiO2 nanoparticles and disperse anatase TiO2 nanoparticles uniformly on the surface of rutile TiO2 powders. Rutile TiO2 powders coupled with anatase TiO2 nanoparticles are successfully prepared. Additionally, we compare the photocatalytic activity of these rutile-anatase coupled TiO2 powders under ultraviolet (UV) light and demonstrate that the reason for the improvement of photocatalytic activity is microstructural.
Exotic tilting sheaves, parity sheaves on affine Grassmannians, and the Mirković–Vilonen conjecture
Authors: Mautner Carl , Riche Simon
Published: July 2018

Let

\mathbf G

be a connected reductive group over an algebraically closed field

\mathbb F

of good characteristic, satisfying some mild conditions. In this paper we relate tilting objects in the heart of Bezrukavnikov’s exotic t-structure on the derived category of equivariant coherent sheaves on the Springer resolution of

\mathbf G

, and Iwahori-constructible

\mathbb F

-parity sheaves on the affine Grassmannian of the Langlands dual group. As applications we deduce in particular the missing piece for the proof of the Mirković–Vilonen conjecture in full generality (i.e. for good characteristic), a modular version of an equivalence of categories due to Arkhipov–Bezrukavnikov–Ginzburg, and an extension of this equivalence.
Efficient N2O5 uptake and NO3 oxidation in the outflow of urban Beijing
Authors: Wang Haichao , Lu Keding , Guo Song , Wu Zhijun , Shang Dongjie , Tan Zhaofeng , Wang Yujue , Le Breton Michael , Lou Shengrong , Tang Mingjin , Wu Yusheng , Zhu Wenfei , Zheng Jing , Zeng Limin , Hallquist Mattias , Hu Min , Zhang Yuanhang
Published: July 2018

Abstract. Nocturnal reactive nitrogen compounds play an important role in regional air
pollution. Here we present the measurements of dinitrogen pentoxide
(N2O5) associated with nitryl chloride (ClNO2) and particulate
nitrate (pNO3-) at a suburban site of Beijing in the summer of 2016.
High levels of N2O5 and ClNO2 were observed in the
outflow of the urban Beijing air masses, with 1 min average maxima of 937 and 2900 pptv,
respectively. The N2O5 uptake coefficients,
γ, and ClNO2 yield, f, were experimentally determined
from the observed parameters. The N2O5 uptake coefficient ranged
from 0.012 to 0.055, with an average of 0.034 ± 0.018, which is in the
upper range of previous field studies reported in North America and Europe
but is a moderate value in the North China Plain (NCP), which reflects
efficient N2O5 heterogeneous processes in Beijing. The
ClNO2 yield exhibited high variability, with a range of 0.50 to
unity and an average of 0.73 ± 0.25. The concentration of the nitrate
radical (NO3) was calculated assuming that the thermal equilibrium
between NO3 and N2O5 was maintained. In
NOx-rich air masses, the oxidation of nocturnal biogenic
volatile organic compounds (BVOCs) was dominated by NO3 rather than
O3. The production rate of organic nitrate (ON) via NO3 + BVOCs was
significant, with an average of 0.10 ± 0.07 ppbv h−1. We highlight
the importance of NO3 oxidation of VOCs in the formation of ON and
subsequent secondary organic aerosols in summer in Beijing.
An analysis of the cloud environment over the Ross Sea and Ross Ice Shelf using CloudSat/CALIPSO satellite observations: the importance of synoptic forcing
Authors: Jolly Ben , Kuma Peter , McDonald Adrian , Parsons Simon
Published: July 2018

Abstract. We use the 2B-GEOPROF-LIDAR R04 (2BGL4) and R05 (2BGL5) products and the
2B-CLDCLASS-LIDAR R04 (2BCL4) product, all generated by combining CloudSat
radar and CALIPSO lidar satellite measurements with auxiliary data, to
examine the vertical distribution of cloud occurrence around the Ross Ice
Shelf (RIS) and Ross Sea region. We find that the 2BGL4 product, used in
previous studies in this region, displays a discontinuity at 8.2 km
which is not observable in the other products. This artefact appears to
correspond to a change in the horizontal and vertical resolution of the
CALIPSO dataset used above this level. We then use the 2BCL4 product to
examine the vertical distribution of cloud occurrence, phase, and type over
the RIS and Ross Sea. In particular we examine how synoptic conditions in the
region, derived using a previously developed synoptic classification, impact
the cloud environment and the contrasting response in the two regions. We
observe large differences between the cloud occurrence as a function of
altitude for synoptic regimes relative to those for seasonal variations.
A stronger variation in the occurrence of clear skies and multi-layer cloud
and in all cloud type occurrences over both the Ross Sea and RIS is
associated more
with synoptic type than seasonal composites. In addition, anomalies from the
mean joint histogram of cloud top height against thickness display
significant differences over the Ross Sea and RIS sectors as a function of
synoptic regime, but are near identical over these two regions when
a seasonal analysis is completed. However, the frequency of particular phases
of cloud, notably mixed phase and water, is much more strongly modulated by
seasonal than synoptic regime compositing, which suggests that temperature is
still the most important control on cloud phase in the region.
Impact of humidity biases on light precipitation occurrence: observations versus simulations
Authors: Bastin Sophie , Drobinski Philippe , Chiriaco Marjolaine , Bock Olivier , Roehrig Romain , Gallardo Clemente , Conte Dario , Dominguez-Alonso Marta , Li Laurent , Lionello Piero , Parracho Ana C.
Published: July 2018

Abstract. This work uses a network of GPS stations over Europe from which a homogenised integrated water vapor (IWV) dataset has been retrieved, completed with colocated temperature and precipitation measurements over specific stations to i) estimate the biases of six regional climate models over Europe in terms of humidity; ii) understand their origins; iii) and finally assess the impact of these biases on the frequency of occurrence of precipitation. The evaluated simulations have been performed in the framework of HYMEX/Med-CORDEX programs and cover the Mediterranean area and part of Europe at horizontal resolutions of 50 to 12 km. The analysis shows that models tend to overestimate the low values of IWV and the use of the nudging technique reduces the differences between GPS and simulated IWV. Results suggest that physics of models mostly explain the mean biases, while dynamics affects the variability. The land surface/atmosphere exchanges affect the estimation of IWV over most part of Europe, especially in summer. The limitations of the models to represent these processes explain part of their baises in IWV. However, models correctly simulate the dependance between IWV and temperature, and specifically the deviation that this relationship experiences regarding the Clausius-Clapeyron law after a critical value of temperature (Tbreak). The high spatial variability of Tbreak indicates that it has a strong dependence on local processes which drive the local humidity sources. This explains why the maximum values of IWV are not necessarely observed over warmer area, that are often dry area. Finally, it is shown over SIRTA observatory (near Paris) that the frequency of occurrence of light precipitation is strongly conditioned by the biases in IWV and by the precision of the models to reproduce the distribution of IWV as a function of the temperature. The results of the models indicate that a similar dependence occurs in other areas of Europe, especially where precipitation has a predominantly convective character. According to the observations, for each range of temperature, there is a critical value of IWV from which precipitation picks up. The critical values and the probability to exceed them are simulated with a bias that depends on the model. Those models which present too often light precipitation generally show lower critical values and higher probability to exceed them.
Mesoscale fine structure of a tropopause fold over mountains
Authors: Woiwode Wolfgang , Dörnbrack Andreas , Bramberger Martina , Friedl-Vallon Felix , Haenel Florian , Höpfner Michael , Johansson Sören , Kretschmer Erik , Krisch Isabell , Latzko Thomas , Oelhaf Hermann , Orphal Johannes , Preusse Peter , Sinnhuber Björn-Martin , Ungermann Jörn
Published: July 2018

Abstract. We report airborne remote-sensing observations of a tropopause fold during two crossings of the polar front jet over Northern Italy on 12 January 2016. The GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) observations allowed for a simultaneous mapping of temperature, water vapour and ozone. They revealed deep, dry and ozone rich intrusions into the troposphere. The mesoscale fine structures of dry filaments at the cyclonic shear side of the jet and tongues of moist air entraining tropospheric air into the stratosphere along the anticyclonic shear side were clearly resolved by GLORIA observations. Vertically propagating mountain waves with recorded temperature residuals exceeding ±3 K were detected above the Apennines. Their presence enhanced gradients of all variables locally in the vicinity of the tropopause. The combination of H2O-O3-correlations with potential temperature reveals an active mixing region and shows clear evidence of troposphere-to-stratosphere and stratosphere-to-troposphere exchange. High-resolution short-term deterministic forecasts of ECMWF's integrated forecast system (IFS) applying GLORIA's observational filter reproduce location, shape, and depth of the tropopause fold very well. The fine structure of the mixing region, however, cannot be reproduced even with the used 9 km horizontal resolution of the IFS. This case study demonstrates convincingly the capabilities of linear limb-imaging observations to resolve mesoscale fine structures in the upper troposphere and lower stratosphere, validates the high quality of the IFS data, and suggests that mountain wave perturbations have the potential to modulate exchange processes in the vicinity of tropopause folds.
Discriminating Between Clouds and Aerosols in the CALIOP
Version 4.1 Data Products
Authors: Liu Zhaoyan , Kar Jayanta , Zeng Shan , Tackett Jason , Vaughan Mark , Avery Melody , Pelon Jacques , Getzewich Brian , Lee Kam-Pui , Magill Brian , Omar Ali , Lucker Patricia , Trepte Charles , Winker David
Published: July 2018

Abstract. The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Operations (CALIPSO) mission released version 4.1 (V4) of their lidar level 2 cloud and aerosol data products in November 2016. These new products were derived from the CALIPSO V4 lidar level 1 data, in which the calibration of the measured backscatter data at both 532 nm and 1064 nm was significantly improved. This paper describes updates to the V4 level 2 cloud-aerosol-discrimination (CAD) algorithm that more accurately differentiates between clouds and aerosols throughout the Earth's atmosphere. The level 2 data products are improved with new CAD probability density functions (PDFs) that were developed to accommodate the calibration changes in the level 1 data. To enable more reliable identification of aerosol layers lofted into the upper troposphere and lower stratosphere, the CAD training dataset used in the earlier data releases was expanded to include stratospheric layers and representative examples of volcanic aerosol layers. The generic stratospheric layer classification of previous versions has been eliminated in V4, and cloud-aerosol classification is now performed on all layers detected everywhere from the surface to 30 km. Cloud-aerosol classification has been further extended to layers detected at single shot resolution, which were previously classified by default as clouds. In this paper, we describe the underlying rationale used in constructing the V4 PDFs and assess the performance of the V4 CAD algorithm in the troposphere and stratosphere. Previous misclassifications of lofted dust and smoke in the troposphere have been largely improved, and volcanic aerosol layers and aerosol layers in the stratosphere are now being properly classified. CAD performance for single-shot layer detections is also evaluated. Most of the single-shot layers classified as aerosol occur within the dust belt, as may be expected. Due to changes in the 532 nm calibration coefficients, the V4 feature finder detects ~9.0 % more features at night and ~2.5 % more during the day. These features are typically weakly scattering and classified about equally as clouds and aerosols. For those tropospheric layers detected in both V3 and V4, the CAD classifications of more than 95 % of all cloud and daytime aerosol layers remain unchanged, as do the classifications of ~89 % of nighttime aerosol layers. Overall, the nighttime net cloud and aerosol fractions remain unchanged from V3 to V4, but the daytime net aerosol fraction is increased by about 2 % and the daytime net cloud fraction is decreased by about 2 %.
Long-term response of oceanic carbon uptake to global warming via physical and biological pumps
Authors: Yamamoto Akitomo , Abe-Ouchi Ayako , Yamanaka Yasuhiro
Published: July 2018

Abstract. Global warming is expected to significantly decrease oceanic carbon uptake and therefore increase atmospheric CO2 and global warming. The primary reasons given in previous studies for such changes in the oceanic carbon uptake are the solubility reduction due to seawater warming and changes in the ocean circulation and biological pump. However, the quantitative contributions of different processes to the overall reduction in ocean uptake are still unclear. In this study, we investigated multi-millennium responses of oceanic carbon uptake to global warming and quantified the contributions of the physical and biological pumps to these responses using an atmosphere–ocean general circulation model and a biogeochemical model. We found that global warming reduced oceanic CO2 uptake by 13 % (30 %) in the first 140 years (after 2000 model years), consistent with previous studies. Our sensitivity experiments showed that this reduction is primarily driven by changes in the organic matter cycle via ocean circulation change and solubility change due to seawater warming. These results differ from most previous studies, in which circulation changes and solubility change from seawater warming are the dominant processes. The weakening of biological production and carbon export induced by circulation change and lower nutrient supply, diminishes the vertical DIC gradient and substantially reduces the CO2 uptake. The weaker deep-ocean circulation decreases the downward transport of CO2 from the surface to the deep ocean, leading to a drop in CO2 uptake in high-latitude regions. Conversely, weaker equatorial upwelling reduces the upward transport of natural CO2 and therefore enhances the CO2 uptake in low-latitude regions. Because these effects cancel each other out, circulation change plays only a small direct role in the reduction of CO2 uptake due to global warming but a large indirect role through nutrient transport and biological processes.
Assessment of hydrothermal alteration on micro- and nanostructures of biocarbonates: quantitative statistical grain-area analysis of diagenetic overprint
Authors: Casella Laura A. , He Sixin , Griesshaber Erika , Fernández-Díaz Lourdes , Harper Elizabeth M. , Jackson Daniel J. , Ziegler Andreas , Mavromatis Vasileios , Dietzel Martin , Eisenhauer Anton , Brand Uwe , Schmahl Wolfgang W.
Published: July 2018

Abstract. The assessment of diagenetic overprint on microstructural and geochemical data gained from fossil archives is of fundamental importance for understanding palaeoenvironments. A correct reconstruction of past environmental dynamics is only possible when pristine skeletons are unequivocally distinguished from altered skeletal elements. Our previous studies (Casella et al., 2017) have shown that replacement of biogenic carbonate by inorganic calcite occurs via an interface coupled dissolution–reprecipitation mechanism. Furthermore, for a comprehensive assessment of alteration, structural changes have to be assessed on the nanoscale as well, which documents the replacement of pristine nanoparticulate calcite by diagenetic nanorhombohedral calcite (Casella et al., 2018a, b). In the present contribution we investigated six different modern biogenic carbonate microstructures for their behaviour under hydrothermal alteration in order to assess their potential to withstand diagenetic overprint and to test the integrity of their preservation in the fossil record. For each microstructure (a) the evolution of biogenic aragonite and calcite replacement by inorganic calcite was examined, (b) distinct carbonate mineral formation steps on the micrometre scale were highlighted, (c) microstructural changes at different stages of alteration were explored, and (d) statistical analysis of differences in basic mineral unit dimensions in pristine and altered skeletons was performed. The latter analysis enables an unequivocal determination of the degree of diagenetic overprint and discloses information especially about low degrees of hydrothermal alteration.
Silicon isotopes of deep-sea sponges: new insights into biomineralisation and skeletal structure
Authors: Cassarino Lucie , Coath Christopher D. , Xavier Joana R. , Hendry Katharine R.
Published: July 2018

Abstract. The silicon isotope composition of deep-sea sponges skeletal element – spicules – reflects the silicic acid (DSi) concentration of their surrounding water, and can be used as natural archives of bottom water nutrients. In order to reconstruct the past silica cycle robustly, it is essential to better constrain the mechanisms of biosilicification, which are not yet well understood. Here, we show that the apparent isotopic fractionation (∆30Si) during spicule formation in deep–sea sponges from the equatorial Atlantic range from −6.74 ‰ to −1.50 ‰ in relatively low DSi concentrations (15 to 35 μM). The wide range in isotopic composition highlights the potential difference in silicification mechanism between the two major classes, Demospongiae and Hexactinellida. We find the anomalies in the isotopic fractionation correlates with skeletal morphology, whereby fused framework structures, characterised by secondary silicification, exhibit extremely light δ30Si signatures. Our results provide insights into the process involved during silica deposition, and indicate that reliable reconstructions of past DSi can only be obtained using silicon isotopes ratios derived from sponges with certain spicule types.
Potentials and pitfalls of permafrost active layer monitoring using the HVSR method: A case study in Svalbard
Authors: Köhler Andreas , Weidle Christian
Published: July 2018

Abstract. Time-lapse monitoring of the sub-surface using ambient seismic noise is a popular method in environmental seismology. We assess the reliability of the Horizontal-to-Vertical Spectral Ratio (HVSR) method for monitoring seasonal permafrost active layer variability in northwest Svalbard. We observe complex HVSR variability between 1 and 50 Hz in the record of a temporary seismic deployment covering frozen and thawn soil conditions between April and August 2016. While strong variations are due to changing noise conditions, mainly affected by wind speed and degrading coupling of instruments during melt season, a seasonal trend is observed at some stations that has most likely a sub-surface structural cause. A HVSR peak emerges close to the Nyquist frequency (50 Hz) in beginning of June which is then gradually gliding down, reaching frequencies of about 15–25 Hz in the end of August. This observation is consistent with HVSR forward-modeling for a set of structural models that simulate different stages of active layer thawing. Our results reveal a number of potential pitfalls when interpreting HVSRs and suggest a careful analysis of temporal variations since HVSR seasonality is not necessarily related to changes in the sub-surface. We compile a list of recommendations for future experiments, including comments on network layouts suitable for array beamforming and waveform correlation methods that can provide essential information on noise source variability. In addition, we investigate if effects of changing noise sources on HVSRs can be avoided by utilizing a directional, narrow-band (4.5 Hz) repeating seismic tremor which is observed at the permanent seismic broadband station KBS in the study area. A significant change of the radial component HVSR shape during summer months is observed for all tremors. We show that a thawn active layer with very low seismic velocities would affect Rayleigh wave ellipticities in the tremor frequency band.
Seismic detection of rockslides at regional scale: Examples from the Eastern Alps and feasibility of kurtosis-based event location
Authors: Fuchs Florian , Lenhardt Wolfgang , Bokelmann Götz ,   the AlpArray Working Group
Published: July 2018

Abstract. Seismic records can provide detailed insight into the mechanisms of gravitational mass movements. Catastrophic events that generate long-period seismic radiation have been studied in detail, and monitoring systems have been developed for applications on very local scale. Here we demonstrate that similar techniques can also be applied to regional seismic networks which show great potential for real-time and large-scale monitoring and analysis of rockslide activity. This manuscript studies 21 moderate-size to large rockslides in the Eastern Alps that were recorded by regional seismic networks within distances of few tens of kilometers to more than 200 km. We develop a simple and fully automatic processing chain that detects, locates, and classifies rockslides based on vertical-component seismic records. We show that a kurtosis-based onset picker is suitable to detect the very emergent onsets of rockslide signals, and to locate the rockslides within a few kilometers from the true origin, using a grid search and a 1D seismic velocity model. Automatic discrimination between rockslides and local earthquakes is possible by a combination of characteristic parameters extracted from the seismic records, such as kurtosis or maximum-to-mean amplitude ratios. We attempt to relate the amplitude of the seismic records with the documented rockslide volume and reveal a potential power-law in agreement with earlier studies. Since our approach is based on simplified methods we suggest and discuss how each step of the automatic processing could be expanded and improved to achieve more detailed results in the future.
An update on the RTTOV fast radiative transfer model (currently at version 12)
Authors: Saunders Roger , Hocking James , Turner Emma , Rayer Peter , Rundle David , Brunel Pascal , Vidot Jerome , Roquet Pascale , Matricardi Marco , Geer Alan , Bormann Niels , Lupu Cristina
Published: July 2018

Abstract. This paper gives an update of the RTTOV (Radiative Transfer for TOVS) fast radiative transfer model, which is widely used in the satellite retrieval and data assimilation communities. RTTOV is a fast radiative transfer model for simulating top-of-atmosphere radiances from passive visible, infrared and microwave downward-viewing satellite radiometers. In addition to the forward model, it also optionally computes the tangent linear, adjoint and Jacobian matrix providing changes in radiances for profile variable perturbations assuming a linear relationship about a given atmospheric state. This makes it a useful tool for developing physical retrievals from satellite radiances, for direct radiance assimilation in NWP models, for simulating future instruments, and for training or teaching with a graphical user interface. An overview of the RTTOV model is given, highlighting the updates and increased capability of the latest versions, and it gives some examples of its current performance when compared with more accurate line-by-line radiative transfer models and a few selected observations. The improvement over the original version of the model released in 1999 is demonstrated.