bluuebunny/crossref_metadata_2025 huggingface dataset:
Signals of the Neuropilin-1–MET Axis and Cues of Mechanical Force Exertion Converge to Elicit Inflammatory Activation in Coherent Endothelial Cells
Authors: Rezaei Maryam , Martins Cavaco Ana C. , Seebach Jochen , Niland Stephan , Zimmermann Jana , Hanschmann Eva-Maria , Hallmann Rupert , Schillers Hermann , Eble Johannes A.
Published: January 2019

The neuropilin-1 (NRP1)-MET signaling axis regulates the motility of individual endothelial cells (ECs). It is unknown how this signaling pathway affects the endothelial barrier in coherent ECs forming a tight monolayer. We hypothesized that it is involved both in modulation of the endothelial barrier and in EC activation. To investigate the role of NRP1–MET signaling in inflammatory processes (e.g., systemic inflammatory response syndrome [SIRS] or snakebite-induced SIRS-like conditions), we employed the C-type lectin-related protein rhodocetin-αβ (RCαβ) as a specific trigger of this signal axis in ECs in vitro. In coherent HUVECs, RCαβ reinforced the actin cytoskeleton and increased cell stiffness, thus favoring vascular endothelial cadherin–mediated transmission of intercellular forces. Increased cell stiffness was associated with enhanced activation of RhoA and nuclear translocation of NF-κB. Simultaneously, RCαβ-triggered signaling via the NRP1–MET axis increased EC monolayer permeability, induced transcription of proinflammatory genes such as ICAM-1 and, consequently, leukocyte tethering. The RCαβ-induced transcriptome differed from that induced by hepatocyte growth factor, although in both cases the same tyrosine kinase, MET, was involved. This was due to RCαβ-mediated recruitment of the MET coreceptor NRP1 and additional Rho-mediated activation of the actomyosin system. RCαβ induced similar transcriptional and cellular changes if external shear forces were applied. These data highlight the modulatory role of NRP1 as MET coreceptor, and they explain how some snake venoms induce SIRS-like conditions. Additionally, this study demonstrates that inflammatory activation of coherent ECs is triggered by converging signals that are induced by NRP1–MET signaling and influenced by intercellular forces.
An exploration of supply chain risk management in the South African third-party logistics industry
Authors: Meyer Arno , Niemann Wesley , Uys Gerhard , Beetge Déan
Published: January 2019

Orientation: The management of supply chain risks, disruptions and vulnerabilities has become a significant issue in supply chain management research in recent times.Research purpose: The purpose of this study was threefold, namely to (1) determine whether there is a clear understanding of supply chain risk management (SCRM) within the South African third-party logistics service providers (3PL) industry, (2) investigate the primary sources that lead to disruptions and vulnerabilities within the supply chains of South African 3PL organisations and (3) establish the current tools or methods used by supply chain practitioners to mitigate supply chain risks within the 3PL industry in South Africa.Motivation for the study: Supply chain risks are ever increasing and evolving which may have a substantial influence on organisational and supply chain performance.Research design, approach and method: A generic qualitative research method was used to gather data. A total of 20 purposively selected participants drawn from 20 3PL organisations with headquarters located in Gauteng province participated in semi-structured interviews.Main findings: The findings indicate a juxtaposition regarding South African 3PL supply chain practitioners’ understanding of SCRM compared to literature, as the participants were found to only identify certain tenets of SCRM with no single participant comprehensively describing SCRM according to the literature. External disruptions, namely customer- and supply-side disruptions within the South African 3PL industry were found to be the primary sources of supply chain disruptions. The findings further indicate that supply chain vulnerabilities emanate predominantly from labour strikes and cyberattacks.Practical/managerial implications: The implementation of SCRM is constrained by the high costs of implementation, the unwillingness of supply chain partners to buy into SCRM, power imbalances in supply chain relationships and other uncontrollable factors between different supply chain members.Contribution/value-add: Supply chain practitioners in the 3PL industry should realise the significance of effective SCRM practices, as well as the positive impact proactive SCRM practices could have on their organisations as well as on supply chain partners.
Entrepreneurial development in South Africa through innovation: A model for poverty alleviation
Authors: Francke Errol , Alexander Bennett
Published: January 2019

Orientation: The development agency could be equipped with a model that will assist them in supporting mobile application development entrepreneurs towards enhanced competitiveness that could assist in alleviating poverty and reducing economic inequality.Research purpose: The purpose of this study is to explore the evolution of a model to support mobile application development entrepreneurs towards enhanced competitiveness.Motivation for the study: This study was motivated by the views on black economic empowerment where little has been done to impact the lives of black people on a larger scale. Broader participation of black people in the formal economy is required to achieve sustainable development and prosperity. Studies suggest that innovation through technology transfer is regarded as a contributor to economic growth.Research design, approach and method: This study adopted the Critical Realist Methodology Model via an inductive research approach. Focused interviews with academics, small and medium-sized enterprises in the innovation and technology industry and development agencies were conducted.Main findings: There is business potential in mobile applications, but entrepreneurs have difficulty in commercialising these. They could be assisted with a model that would transform their applications into real business opportunities.Practical/managerial implications: The antidote to disruptive innovation is a management response. What is required from management is that it needs to bring about a paradigm shift in the way that the whole notion of a business is remodelled.Contribution/value-add: This study reveals a multi-factorial strategy model in the form of the Disruptive Innovation State Response Model that could support mobile application development entrepreneurs towards enhanced competitiveness.
Usos del WhatsApp en el estudiante universitario español. Pros y contras
Authors: Fondevila-Gascón Joan Francesc , Marqués-Pascual Joaquín , Mir-Bernal Pedro , Polo-López Marc
Published: January 2019

Introducción: El objetivo de esta investigación es analizar de qué manera impacta el uso de los servicios de mensajería instantánea en el entorno universitario español y qué consecuencias positivas y negativas genera en el comportamiento estudiantil. Para ello se trabajó sobre la aplicación más popular en el territorio en cuestión, WhatsApp, y la utilización que de ella hacen los universitarios. Metodología: La investigación desarrollada utiliza la técnica cuantitativa (encuestas a una muestra n= 332), al efecto de determinar el uso que se les da a los mensajes de texto convencionales, así como otras opciones de la mensajería instantánea (como puede ser la voz o las imágenes). Asimismo, se analizaron algunos impactos en el entorno académico como, por ejemplo, el posible estrés que genera en el comportamiento humano. Resultados y conclusiones: Destacan la comodidad y la gratuidad de WhatsApp que impulsan el uso en el entorno educativo. Se puede constatar que la mayoría de los estudiantes utiliza este tipo de aplicaciones de mensajería instantánea también para cuestiones relacionadas con los asuntos universitarios –aparte de su vida personal–. Además, se observa que un porcentaje muy alto de los grupos analizados pertenece a algún chat grupal relacionado con los estudios o está incluido en grupos de conversación sobre materias académicas.
Кластерная реализация положительных представлений расщепленной действительной квантовой борелевской подалгебры
Authors: Ip Ivan Chi-Ho
Published: January 2019

В предыдущей работе автора изучались положительные представления расщепленных действительных квантовых групп $\mathcal U_{q\tilde q}(\mathfrak g_{\mathbb R})$ с сужением на борелевскую часть и было показано, что они замкнуты относительно тензорного произведения. Тем не менее разложение на тензорные множители было построено абстрактно c использованием представления Гельфанда-Наймарка-Сегала $C^*$-алгебраической версии квантовых групп Дринфельда-Джимбо. В настоящей работе с помощью недавно разработанного метода кластерной реализации квантовых групп разложение получено в явном виде путем построения последовательности кластреных мутаций в соответствующей диаграмме колчана, представляющей тензорное произведение.
Представления ортогональных и симплектических янгианов и алгебр Ли
Authors: Karakhanyan David Roudolph , Kirshner R
Published: January 2019

С помощью RLL-соотношений Янга-Бакстера, которые содержат фундаментальную $R$-матрицу с $so(n)$- или $sp(2m)$-симметрией, определяются ортогональные и симплектические янгианы. В качестве ограничений, налагаемых на веса соответствующих представлений, исследуются условия разрешимости первого и второго порядков.
Строгие версии интегрируемых иерархий псевдоразностных операторов и сопутствующих задач Коши
Authors: Helminck Gerard F , Poberezhny Vladimir Andreevich , Polenkova Svetlana Vladimirovna
Published: January 2019

В алгебре $Ps\Delta$ псевдоразностных операторов рассмотрены две деформации подалгебры Ли, натянутые на положительные степени обратимого постоянного псевдоразностного оператора $\Lambda_0$ первой степени. Первая деформация осуществляется в $Ps\Delta$ группой, соответствующей подалгебре Ли $Ps\Delta_{<0}$ элементов отрицательной степени, а вторая - группой, соответствующей подалгебре Ли $Ps\Delta_{\leq 0}$ элементов нулевой степени или ниже. Рассмотрены деформации, эволюции которых описываются совместными системами уравнений Лакса, заданных выбором зависящей от $\Lambda_0$ подалгебры Ли, дополняющей подалгебры Ли $Ps\Delta_{<0}$ и $Ps\Delta_{\le 0}$ соответственно. Это приводит к двум интегрируемым иерархиям, связанным с $\Lambda_0$. Иерархия более широкой деформации называется строгой версией первой иерархии из-за формы уравнений Лакса. Когда матрица $\Lambda_0$ отвечает сдвигу, иерархия, соответствующая простейшей деформации, известна как дискретная иерархия Кадомцева-Петвиашвили. Показано, что обе иерархии допускают представление нулевой кривизны, исследована разрешимость сопутствующих задач Коши.
Эквивариантные векторные расслоения над квантовыми проективными пространствами
Authors: Mudrov Andrei Igorevich
Published: January 2019

С использованием параболических модулей Верма над квантовой общей линейной группой строятся эквивариантные векторные расслоения над квантовыми проективными пространствами. При помощи альтернативной реализации квантованного координатного кольца проективного пространства как подалгебры в алгебре функций на квантовой группе квантовые векторные расслоения переформулированы в терминах квантовых симметрических пар. Таким образом, на основе квантовой двойственности Фробениуса доказана полная приводимость модулей над соответствующими коидеал-подалгебрами, выступающими в роли квантового стабилизатора начальной точки.
Следы и суперследы на алгебрах симплектических отражений
Authors: Konstein Semen Efimovich , Tyutin Igor Viktorovich
Published: January 2019

Алгебра симплектических отражений $H_{1,\nu}(G)$ имеет $T(G)$-мерное пространство следов и, когда рассматривается как супералгебра с естественной четностью, $S(G)$-мерное пространство суперследов. Значения $T(G)$ и $S(G)$ зависят от группы симплектических отражений $G$ и не зависят от параметра $\nu$. Приведены значения $T(G)$ и $S(G)$ для групп, порожденных системами корней, и для групп $G=\Gamma\wr S_N$, где $\Gamma$ - конечная подгруппа группы $Sp(2,\mathbb{C})$.
Apresentação
Authors: Butturi Junior Atilio
Published: January 2019

Apresentação v.15, n.4, 2018.
A modalização discursiva como índice de argumentatividade nos gêneros acadêmicos
Authors: Nascimento Erivaldo Pereira do
Published: January 2019

O objetivo deste artigo é mostrar como a modalização discursiva funciona nos gêneros acadêmicos, imprimindo argumentatividade, ou seja, orientando os enunciados em razão de determinadas conclusões. Trata-se de reflexões feitas sobre o fenômeno da modalização nos referidos gêneros, a partir de investigações científicas de natureza qualitativa e de caráter descritivo e interpretativista.  Para tal, fundamentamo-nos nos estudos sobre a Modalização Discursiva, a partir de Cervoni (1989), Castilho e Castilho (1993), Koch (2012), Nascimento (2009, 2010) e Nascimento e Silva (2012), além dos estudos sobre a argumentação linguística de Ducrot (1987, 1988). A descrição do fenômeno da modalização nos gêneros investigados permitiu-nos verificar que a modalização é uma estratégia presente em todos eles (ata administrativo-acadêmica, resumo, resenha, projeto de pesquisa de TCC, monografia de TCC e artigo científico) e que é utilizada com diferentes funções discursivas, produzindo diversos efeitos de sentido: assimilação, distanciamento e avaliação.
Interventions to Address the Needs of Adults With Postconcussion Syndrome: A Systematic Review
Authors: Jaber Ala’a F. , Hartwell Julie , Radel Jeff D.
Published: January 2019

Postconcussion syndrome (PCS) affects physical, cognitive, and emotional functioning. Existing reviews of interventions to address PCS are limited to psychological and rehabilitation interventions and to child and adolescent populations. We conducted a systematic review integrating current evidence about interventions for adults with PCS. The inclusion criteria were intervention studies of adults (ages ≥18 yr) with PCS that evaluated recovery from PCS symptoms and focused on functional outcomes; 10 studies met the criteria. Included studies demonstrated medium to high levels of evidence and investigated psychotherapy, counseling, social support, self-management strategies, individualized rehabilitation, hyperbaric oxygen interventions, and group-based cognitive–behavioral therapy. Outcomes included reduced postconcussion symptoms, improved cognitive function, enhanced quality of life, and increased community integration. The evidence supports psychotherapy, counseling, and social support interventions as being beneficial for cognitive and emotional functions in adults with PCS.
The advantages of a spine coil over a torso coil in magnetic resonance imaging examination of the sternoclavicular joints
Authors: Kusak Artur Stefan , Podgórski Michał Tomasz , Grzelak Piotr , Kwapisz Adam
Published: January 2019

Purpose

There are two standard methods for an magnetic resonance imaging (MRI) examination of the sternoclavicular joints: with loop coils and the patient in the prone position, or with torso coils with the patient in a supine position. In some centres these joints are examined with the spine coil in a patient laying prone. There are no reports on the advantages of this method. Our hypothesis is that despite different MRI systems, application of a spine coil will improve examination quality.

Material and methods

Twenty-one healthy volunteers (10 female, 11 male, mean age 25 years) were randomised into three groups and scanned using three different MRI scanners (1.5T: Siemens Avanto, Philips Ingenia, 3.0T: Philips Achieva). Each volunteer was examined twice: using a standard protocol with a torso coil and with a spine coil, in prone position. The two groups were compared with regard to the intensity of motion artefacts using the χ2 test, and to the signal-to-noise ratio with the Wilcoxon signed-rank test.

Results

Application of a spine coil resulted in a significant decrease in the number of motion artefacts in all three planes (axial: p = 0.0004; sagittal: p < 0.0001; coronal: p = 0.0054). Moreover, the signal-to-noise ratio was significantly increased with the application of a spine coil (28.6 ± 8.6 vs. 18.5 ± 7.3, respectively; p = 0.0002).

Conclusions

Application of a spine coil with the patient in a prone position is suitable for MRI evaluation of the sterno­clavicular joints. It allows a higher signal-to-noise ratio and a lower intensity of motion artefacts to be obtained compared to a torso coil.
Effects of turbulence structure and urbanization on the heavy haze pollution process
Authors: Ren Yan , Zhang Hongsheng , Wei Wei , Wu Bingui , Cai Xuhui , Song Yu
Published: January 2019

Abstract. In this paper, an automated algorithm is
developed, which is used to identify the spectral gap during the heavy haze
pollution process, reconstruct acquired data, and obtain pure turbulence
data. Comparisons of the reconstructed turbulent flux and eddy covariance
(EC) flux show that there are overestimations regarding the exchange between
the surface and the atmosphere during heavy haze pollution episodes. After
reconstruction via the automated algorithm, pure turbulence data can be
obtained. We introduce a definition to characterize the local intermittent
strength of turbulence (LIST). The trend in the LIST during pollution
episodes shows that when pollution is more intense, the LIST is smaller, and
intermittency is stronger; when pollution is weaker, the LIST is larger, and
intermittency is weaker. At the same time, the LIST at the city site is
greater than at the suburban site, which means that intermittency over the
complex city area is weaker than over the flat terrain area. Urbanization
seems to reduce intermittency during heavy haze pollution episodes, which
means that urbanization reduces the degree of weakening in turbulent exchange
during pollution episodes. This result is confirmed by comparing the average
diurnal variations in turbulent fluxes at urban and suburban sites during
polluted and clean periods. The sensible heat flux, latent heat flux,
momentum flux, and turbulent kinetic energy (TKE) in urban and suburban areas
are all affected when pollution occurs. Material and energy exchanges between
the surface and the atmosphere are inhibited. Moreover, the impact of the
pollution process on suburban areas is much greater than on urban areas. The
turbulent effects caused by urbanization seem to help reduce the consequences
of pollution under the same weather and pollution source condition, because
the turbulence intermittency is weaker, and the reduction in turbulence
exchange is smaller over the urban underlying surface.
Heterogeneous ice nucleation on dust particles sourced from nine deserts worldwide – Part 2: Deposition nucleation and condensation freezing
Authors: Boose Yvonne , Baloh Philipp , Plötze Michael , Ofner Johannes , Grothe Hinrich , Sierau Berko , Lohmann Ulrike , Kanji Zamin A.
Published: January 2019

Abstract. Mineral dust particles from deserts are amongst the most common
ice nucleating particles in the atmosphere. The mineralogy of desert dust
differs depending on the source region and can further fractionate during the
dust emission processes. Mineralogy to a large extent explains the ice
nucleation behavior of desert aerosol, but not entirely. Apart from pure
mineral dust, desert aerosol particles often exhibit a coating or are mixed with small amounts of
biological material. Aging on the ground or
during atmospheric transport can deactivate nucleation sites, thus strong
ice nucleating minerals may not exhibit their full potential. In the partner
paper of this work, it was shown that mineralogy determines most but not
all of the ice nucleation behavior in the immersion mode found for desert dust.
In this study, the influence of semi-volatile organic compounds and the
presence of crystal water on the ice nucleation behavior of desert aerosol is
investigated. This work focuses on the deposition and condensation ice
nucleation modes at temperatures between 238 and 242 K of 18 dust samples
sourced from nine deserts worldwide. Chemical imaging of the particles' surface
is used to determine the cause of the observed differences in ice nucleation.
It is found that, while the ice nucleation ability of the majority of the dust
samples is dominated by their quartz and feldspar content, in one
carbonaceous sample it is mostly caused by organic matter, potentially
cellulose and/or proteins. In contrast, the ice nucleation ability of
an airborne Saharan sample is found to be diminished, likely by semi-volatile
species covering ice nucleation active sites of the minerals. This study
shows that in addition to mineralogy, other factors such as organics and
crystal water content can alter the ice nucleation behavior of desert aerosol
during atmospheric transport in various ways.
Subgrid variations of the cloud water and droplet number concentration over the tropical ocean: satellite observations and implications for warm rain simulations in climate models
Authors: Zhang Zhibo , Song Hua , Ma Po-Lun , Larson Vincent E. , Wang Minghuai , Dong Xiquan , Wang Jianwu
Published: January 2019

Abstract. One of the challenges in
representing warm rain processes in global climate models (GCMs) is related
to the representation of the subgrid variability of cloud properties, such as
cloud water and cloud droplet number concentration (CDNC), and the effect
thereof on individual precipitation processes such as autoconversion. This
effect is conventionally treated by multiplying the resolved-scale warm rain
process rates by an enhancement factor (Eq) which is derived from
integrating over an assumed subgrid cloud water distribution. The assumed
subgrid cloud distribution remains highly uncertain. In this study, we derive
the subgrid variations of liquid-phase cloud properties over the tropical
ocean using the satellite remote sensing products from Moderate Resolution
Imaging Spectroradiometer (MODIS) and investigate the corresponding
enhancement factors for the GCM parameterization of autoconversion rate. We
find that the conventional approach of using only subgrid variability of
cloud water is insufficient and that the subgrid variability of CDNC, as well
as the correlation between the two, is also important for correctly
simulating the autoconversion process in GCMs. Using the MODIS data which
have near-global data coverage, we find that Eq shows a strong
dependence on cloud regimes due to the fact that the subgrid variability of
cloud water and CDNC is regime dependent. Our analysis shows a significant
increase of Eq from the stratocumulus (Sc) to cumulus (Cu) regions.
Furthermore, the enhancement factor EN due to the subgrid variation of
CDNC is derived from satellite observation for the first time, and results
reveal several regions downwind of biomass burning aerosols (e.g., Gulf of
Guinea, east coast of South Africa), air pollution (i.e., East China Sea),
and active volcanos (e.g., Kilauea, Hawaii, and Ambae, Vanuatu), where the
EN is comparable to or even larger than Eq, suggesting an important
role of aerosol in influencing the EN. MODIS observations suggest that
the subgrid variations of cloud liquid water path (LWP) and CDNC are
generally positively correlated. As a result, the combined enhancement
factor, including the effect of LWP and CDNC correlation, is significantly
smaller than the simple product of Eq⋅EN. Given the importance
of warm rain processes in understanding the Earth's system dynamics and water
cycle, we conclude that more observational studies are needed to provide a
better constraint on the warm rain processes in GCMs.
Insight into the Composition of Organic Compounds (≥ C6) in PM2.5 in Wintertime in Beijing, China
Authors: Lyu Ruihe , Shi Zongbo , Alam Mohammed Salim , Wu Xuefang , Liu Di , Vu Tuan V. , Stark Christopher , Fu Pingqing , Feng Yinchang , Harrison Roy M.
Published: January 2019

Abstract. Organic matter is a major component of PM2.5 in megacities. In order to understand the detailed characteristics of organic compounds (> C6) at a molecular level on non-haze and haze days, we determined more than 300 organic compounds in the PM2.5 from an urban area of Beijing in November-December 2016 using two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC-TOFMS). The identified organic compounds have been classified into groups, and quantitative methods were used to calculate their concentrations. Primary emission sources make significant contributions to the atmospheric organic compounds and six groups (including n-alkanes, PAHs, levoglucosan, branched-alkanes, n-alkenes and alkyl-benzenes) account for 66 % of total identified organic compound mass. In addition, polycyclic aromatic hydrocarbons (PAHs), and oxygenated PAHs (OPAHs) were abundant amongst the atmospheric organic compounds on both haze and non-haze days. A near-unimodal molecular distribution, peaking approximately within the range of C19-C28, was observed in most hydrocarbon groups. In addition, the concentrations of unidentified compounds were also estimated in the present study. The total identified compounds account for approximately 47 % of total organic compounds (> C6) in the chromatogram on both the non-haze and haze days. The total mass concentrations of organic compounds (> C6) in the chromatogram were 4.0 μg m−3 and 7.4 μg m−3 on the non-haze and haze days respectively, accounting for 26.5 % and 18.5 % of OM respectively on those days. There is strong evidence that the organic aerosol is more highly oxidised, and hence less GC-volatile on haze days.
Observationally constrained analysis of sea salt aerosol in the marine atmosphere
Authors: Bian Huisheng , Froyd Karl , Murphy Daniel M. , Dibb Jack , Chin Mian , Colarco Peter R. , Darmenov Anton , da Silva Arlindo , Kucsera Tom L. , Schill Gregory , Yu Hongbin , Bui Paul , Dollner Maximillan , Weinzierl Bernadett , Smirnov Alexander
Published: January 2019

Abstract. Atmospheric sea salt plays important roles in marine cloud formation and atmospheric chemistry. We performed an integrated analysis of NASA GEOS model simulations run with the GOCART aerosol module, in situ measurements from the PALMS and SAGA instruments obtained during the NASA ATom campaign, and aerosol optical depth (AOD) measurements from AERONET Marine Aerosol Network (MAN) sun photometers and from MODIS satellite observations to better constrain sea salt in the marine atmosphere. ATom measurements and GEOS model simulation both show that sea salt concentrations over the Pacific and Atlantic oceans have a strong vertical gradient, varying up to four orders of magnitude from the marine boundary layer to free troposphere. The modeled residence times suggest that the lifetime of sea salt particles with dry diameter less than 3 μm is largely controlled by wet removal, followed next by turbulent process. During both boreal summer and winter, the GEOS simulated sea salt mass mixing ratios agree with SAGA measurements in the marine boundary layer (MBL) and with PALMS measurements above the MBL. However, comparison of AOD from GEOS with AERONET/MAN and MODIS aerosol retrievals indicated that the model underestimated AOD over the oceans where sea salt dominates. The apparent discrepancy of slightly overpredicted concentration and large underpredicted AOD could not be explained by biases in the model RH, which was found to be comparable to or larger than the in-situ measurements. This conundrum is at least partially explained by the sea salt size distribution; where the GEOS simulation has much less sea salt percentage-wise in the smaller particles than was observed by PALMS. Model sensitivity experiments indicated that the simulated sea salt is better correlated with measurements when the sea salt emission is calculated based on the friction velocity and with consideration of sea surface temperature dependence than that parameterized with the 10-m winds.
Gravimetrically prepared carbon dioxide standards in support of atmospheric research
Authors: Hall Bradley D. , Crotwell Andrew M. , Miller Benjamin R. , Schibig Michael , Elkins James W.
Published: January 2019

Abstract. We have explored a one-step method for gravimetric preparation of
CO2-in-air standards in aluminum cylinders. We consider both adsorption
to stainless steel surfaces used in the transfer of highly pure CO2 and
adsorption of CO2 to cylinder walls. We demonstrate that CO2-in-air
standards can be prepared with relatively low uncertainty (∼ 0.04 %, ∼95 % confidence level) by introducing aliquots
whose masses are known to high precision and by using well-characterized
cylinders. Five gravimetric standards, prepared over the nominal range of 350 to
490 µmol mol−1 (parts per million, ppm), showed excellent
internal consistency, with residuals from a linear fit equal to 0.05 ppm.
This work compliments efforts to maintain the World Meteorological
Organization, Global Atmosphere Watch, mole fraction scale for carbon dioxide
in air, widely used for atmospheric monitoring. This gravimetric technique
could be extended to other atmospheric trace gases, depending on the vapor
pressure of the gas.
Upgrade and automation of the JPL Table Mountain Facility tropospheric ozone lidar (TMTOL) for near-ground ozone profiling and satellite validation
Authors: Chouza Fernando , Leblanc Thierry , Brewer Mark , Wang Patrick
Published: January 2019

Abstract. As part of international efforts to monitor air quality,
several satellite missions such as the Tropospheric Monitoring Instrument
(TROPOMI) were deployed and others, like Tropospheric Emissions: Monitoring
Pollution (TEMPO), are planned for the near future. In support of the
validation of these missions, major upgrades to the tropospheric ozone lidar
located at the Jet Propulsion Laboratory Table Mountain Facility (TMF) were
recently performed. These modifications include the full automation of the
system, which now allows unattended measurements during frequent satellite
overpasses, and a new receiver that extends the measurement capabilities of
the system down to 100 m above surface. The automation led to the systematic operation of the lidar during daily
TROPOMI overpasses, providing more than 139 reference profiles since
January 2018. Ozone profiles retrieved using the new lidar receiver were
compared to ozonesonde profiles obtained from a co-located tethered balloon.
An agreement of about 5 % with the ozonesonde down to an altitude range of
100 m a.g.l. was observed. Furthermore, the stability of the receiver
configuration was investigated. Comparisons between the lowest point
retrieved by the lidar and a co-located surface ozone photometer showed no
sign of drift over a 2-month test period and an agreement better than
10 %. Finally, measurements from a 24 h intensive measurement period
during a stratospheric intrusion event showed good agreement with two free-flying ozonesondes. These comparisons revealed localized differences between
sonde and lidar, possibly owing to the differing vertical resolutions
(between 52 and 380 m for lidar and about 100 m for the sonde).
Evaluating the Potential of PPK Direct Georeferencing for UAV-SfM Photogrammetry
and Precise Topographic Mapping
Authors: Zhang He , Aldana-Jague Emilien , Clapuyt François , Wilken Florian , Vanacker Veerle , Van Oost Kristof
Published: January 2019

Abstract. Images captured by Unmanned aerial vehicle (UAV) and processed by Structure from Motion (SfM) photogrammetry are increasingly used in geomorphology to obtain high resolution topography data. Conventional georeferencing using ground control points (GCPs) provides reliable positioning but the geometrical accuracy critically depends on the number and spatial layout of the GCPs. This limits the time- and cost-effectiveness. Direct georeferencing of the UAV images with differential GNSS, such as PPK (Post-Processing Kinematic), may overcome these limitations by providing accurate and directly georeferenced surveys. To investigate the positional accuracy, repeatability and reproducibility of digital surface models (DSMs) generated by a UAV-PPK-SfM workflow, we carried out multiple flight missions with different camera/UAV systems. Our analysis showed that the PPK solution provides the same accuracy (mean: ca. 0.01 m, RMSE: ca. 0.03 m) as the GCP method. Furthermore, our results indicated that camera properties (i.e., focal length, resolution, sensor quality) have an impact on the accuracy but planimetric and altimetric errors remained in the range of 0.011 to 0.024 m. By analysing the repeatability of DSM construction over a time period of a few months, our study demonstrates that a UAV-PPK-SfM workflow can provide consistent, repeatable 4D data with an accuracy of a few centimetres without the use of GCPs. An uncertainty analysis showed that the minimum level of topographical change detection was ca. ±0.04 m for a high-end DSLR camera and ca. ±0.08 m for an action camera (for a flight height of 45 m). The level of detection substantially improved when reducing the UAV flight height. This study demonstrates the repeatability, reproducibility and efficiency of a PPK-SfM workflow in the context of 4D earth surface monitoring with time-laps SfM photogrammetry. As such, it should be considered as an efficient tool to monitor geomorphic processes accurately and quickly at a very high spatial and temporal resolution.
Using phase lags to evaluate model biases in simulating the diurnal cycle of evapotranspiration: a case study in Luxembourg
Authors: Renner Maik , Brenner Claire , Mallick Kaniska , Wizemann Hans-Dieter , Conte Luigi , Trebs Ivonne , Wei Jianhui , Wulfmeyer Volker , Schulz Karsten , Kleidon Axel
Published: January 2019

Abstract. While modeling approaches of evapotranspiration (λE) perform
reasonably well when evaluated at daily or monthly timescales, they can show systematic
deviations at the sub-daily timescale,
which results in potential biases in modeled λE to global climate
change. Here we decompose the diurnal variation of heat fluxes and
meteorological variables into their direct response to incoming solar
radiation (Rsd) and a phase shift to Rsd. We analyze data from an
eddy-covariance (EC) station at a temperate grassland site, which experienced a
pronounced summer drought. We employ three structurally different modeling
approaches of λE, which are used in remote sensing retrievals, and
quantify how well these models represent the observed diurnal cycle under
clear-sky conditions. We find that energy balance residual approaches, which
use the surface-to-air temperature gradient as input,
are able to reproduce the reduction of the phase lag from wet to dry conditions. However, approaches
which use the vapor pressure deficit (Da) as the driving gradient
(Penman–Monteith) show significant deviations from the observed phase lags,
which is found to depend on the parameterization of surface conductance to
water vapor. This is due to the typically strong phase lag of 2–3 h
of Da, while the observed phase lag of λE is only on the order of
15 min. In contrast, the temperature gradient shows phase differences in
agreement with the sensible heat flux and represents the wet–dry difference
rather well. We conclude that phase lags contain important information on
the different mechanisms of diurnal heat storage and exchange and, thus,
allow a process-based insight to improve the representation of
land–atmosphere (L–A) interactions in models.
Response time to flood events using a social vulnerability index (ReTSVI)
Authors: Hofflinger Alvaro , Somos-Valenzuela Marcelo A. , Vallejos-Romero Arturo
Published: January 2019

Abstract. Current methods to estimate evacuation time during a natural disaster do not
consider the socioeconomic and demographic characteristics of the population.
This article develops the Response Time by Social Vulnerability Index
(ReTSVI). ReTSVI combines a series of modules that are pieces of information
that interact during an evacuation, such as evacuation rate curves,
mobilization, inundation models, and social vulnerability indexes, to create
an integrated map of the evacuation rate in a given location. We provide an
example of the application of ReTSVI in a potential case of a severe flood
event in Huaraz, Peru. The results show that during the first 5 min of the
evacuation, the population that lives in neighborhoods with a high social
vulnerability evacuates 15 % and 22 % fewer people than the blocks
with medium and low social vulnerability. These differences gradually
decrease over time after the evacuation warning, and social vulnerability
becomes less relevant after 30 min. The results of the application example
have no statistical significance, which should be considered in a real case
of application. Using a methodology such as ReTSVI could make it possible to
combine social and physical vulnerability in a qualitative framework for
evacuation, although more research is needed to understand the socioeconomic
variables that explain the differences in evacuation rate.
A method of deriving operation-specific ski run classes for avalanche risk management decisions in mechanized skiing
Authors: Sterchi Reto , Haegeli Pascal
Published: January 2019

Abstract. An in-depth understanding of the nature of the available terrain and its
exposure to avalanche hazard is crucial for making informed risk management
decisions when travelling in the backcountry. While the Avalanche Terrain
Exposure Scale (ATES) is broadly used for providing recreationists with
terrain information, this type of terrain classification has so far only seen
limited adoption within the professional ski guiding community. We
hypothesize that it is the generic nature and small number of terrain classes
of ATES and its precursor systems that prevent them from offering meaningful
assistance to professional decision makers. Working with two mechanized
skiing operations in British Columbia, Canada, we present a new approach for
deriving terrain classifications from daily terrain assessment records. We
used a combination of self-organizing maps and hierarchical clustering to
identify groups of ski runs that have been assessed similarly in the past and
organized them into operation-specific ski run hierarchies. We then examined
the nature of the emerging ski run hierarchies using comprehensive run
characterizations from experienced guides. Our approach produces
high-resolution ski run hierarchies that offer a more nuanced and meaningful
perspective on the available skiing terrain and provide new opportunities for
examining professional avalanche risk management practices and developing
meaningful decision aids.
Comparing the efficiency of hypoxia mitigation strategies in an urban, turbid tidal river, using a coupled hydro sedimentary–biogeochemical model
Authors: Lajaunie-Salla Katixa , Sottolichio Aldo , Schmidt Sabine , Litrico Xavier , Binet Guillaume , Abril Gwenaël
Published: January 2019

Abstract. In view of future coastal hypoxia widespreading, it is essential to define management solutions to preserve a good quality of coastal ecosystems. The lower Tidal Garonne River (TGR, SW France), characterized by the seasonal presence of a turbidity maximum zone and urban water discharges, is subject to episodic hypoxia events during summer low river flow periods. The future climatic conditions (higher temperature; summer droughts) but also an increasing urbanization could enhance hypoxia risks near the city of Bordeaux in the next decades. A 3D model of dissolved oxygen (DO), which couples hydrodynamics, sediment transport and biogeochemical processes, is used to assess the efficiency of different management solutions on TGR oxygenation during summer low-discharge periods. We have runned different scenarios of reduction of urban sewage overflows, displacement of urban discharges downstream from Bordeaux, and/or temporary river flow support during summer period. The model shows that each option limits hypoxia, but with variable efficiency over time and space. Sewage overflow reduction improves DO levels only locally near the city of Bordeaux. Downstream relocation of wastewater discharges allows to reach better oxygenation level in the lower TGR. The support of low river flow limits the upstream TMZ propagation and dilutes TGR waters with well-oxygenated river waters. Scenarios combining wastewater network management and low water replenishment indicate an improvement in water quality over the entire TGR. These modelling outcomes constitute important tools for local water authorities to develop the most appropriate strategies to limit hypoxia in TGR.
From examination of natural events a proposal for risk mitigation of
lahars by a cellular automata methodology: a case study for Vascún
valley, Ecuador
Authors: Lupiano Valeria , Chidichimo Francesco , Machado Guillermo , Catelan Paolo , Molina Lorena , Straface Salvatore , Crisci Gino M. , Di Gregorio Salvatore
Published: January 2019

Abstract. Lahars are erosive floods, mixtures of water and pyroclastic deposits, they look the biggest environmental disaster as number of fatalities in the volcanic areas. Security measures have been recently adopted in the threatened territories, by constructing retaining dams and embankments in key positions. Such solutions could involve a strong environmental impact for the works and the continuous accumulation of volcanic deposits, such that equilibrium conditions could lack far, triggering more disastrous events. An improved version of the Cellular Automaton model LLUNPIY for lahars simulations is presented. The growing frequency of lahars, maybe for the climatic change, in the Vascún Valley of Tungurahua Volcano, Ecuador has recently produced smaller and less dangerous events, sometimes favoured by the collapse of temporary ponds, generated by small landslides. An investigation is here performed in order to reproduce such situations in controlled way by the use of LLUNPIY simulations. Using precise field data, points are individuated where dams by backfills, easy to collapse, can produce momentary ponds; LLUNPIY simulations permit to project triggering of small lahars by minor rainfall events or to project in the case of larger rainfalls the anticipation of lahar detachment, avoiding simultaneous and dangerous confluence with other lahars.
The vertical structure of precipitation at two stations in East Antarctica derived from micro rain radars
Authors: Durán-Alarcón Claudio , Boudevillain Brice , Genthon Christophe , Grazioli Jacopo , Souverijns Niels , van Lipzig Nicole P. M. , Gorodetskaya Irina V. , Berne Alexis
Published: January 2019

Abstract. Precipitation over Antarctica is the main term in the surface mass
balance of the Antarctic ice sheet, which is crucial for the future evolution
of the sea level worldwide. Precipitation, however, remains poorly documented
and understood mainly because of a lack of observations in this extreme
environment. Two observatories dedicated to precipitation have been set up at
the Belgian station Princess Elisabeth (PE) and at the French station Dumont
d'Urville (DDU) in East Antarctica. Among other instruments, both sites
have a vertically pointing micro rain radar (MRR) working at the K band.
Measurements have been continuously collected at DDU since the austral summer
of
2015–2016, while they have been collected mostly during summer seasons at PE
since 2010, with a full year of observation during 2012. In this study, the
statistics of the vertical profiles of reflectivity, vertical velocity, and
spectral width are analyzed for all seasons. Vertical profiles were separated
into surface precipitation and virga to evaluate the impact of virga on the
structure of the vertical profiles. The climatology of the study area plays
an important role in the structure of the precipitation: warmer and moister
atmospheric conditions at DDU favor the occurrence of more intense
precipitation compared with PE, with a difference of 8 dBZ between both
stations. The strong katabatic winds blowing at DDU induce a decrease in
reflectivity close to the ground due to the sublimation of the snowfall
particles. The vertical profiles of precipitation velocity show significant
differences between the two stations. In general, at DDU the vertical
velocity increases as the height decreases, while at PE the vertical velocity
decreases as the height decreases. These features of the vertical profiles of
reflectivity and vertical velocity could be explained by the more frequent
occurrence of aggregation and riming at DDU compared to PE because of the
lower temperature and relative humidity at the latter, located further in the
interior. Robust and reliable statistics about the vertical profile of
precipitation in Antarctica, as derived from MRRs for instance,
are necessary and valuable for the evaluation of precipitation estimates
derived from satellite measurements and from numerical atmospheric models.
Recent changes in pan-Antarctic surface snowmelt detected by AMSR-E and AMSR2
Authors: Zheng Lei , Zhou Chunxia , Zhang Tingjun , Liang Qi , Wang Kang
Published: January 2019

Abstract. Surface snowmelt in the pan-Antarctic, including the Antarctic sea ice and ice sheet, is crucial to the mass and energy balance in polar regions and can serve as an indicator of climate change. We investigated the spatial and temporal variations of the surface snowmelt over the entire pan-Antarctic as a whole from 2002 to 2017 by using the passive microwave remote sensing data. The stable orbit and appropriate acquisition time of the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) and the Advanced Microwave Scanning Radiometer 2 (AMSR2) enable us to take full advantage of the daily brightness temperature (Tb) variations to detect the surface snowmelt events. In this study, diurnal amplitude variations of AMSR-E/2 vertically polarized 36.5 GHz Tb (DAV36V) were utilized to map the pan-Antarctic snowmelt because it is unaffected by the snow metamorphism. We validated the DAV36V method against the ground-based measurements and further improved the method over the marginal sea ice zone by excluding the effect of open water. Snowmelt detected by AMSR-E/2 data agreed well with that derived by ERA-Interim reanalysis, and much more extensive than that detected by the Special Sensor Microwave/Imager (SSM/I) data. On average, pan-Antarctic snowmelt began on 19 September, and experienced 32 melt events. Annual mean melt extent on the Antarctic ice sheet (AIS) was only 9 % of that on the Antarctic sea ice. Overall, the pan-Antarctic surface snowmelt showed a trend (at 95 % confidence level) toward later melt onset (0.70 days yr−1) during the 2002–2017 period. Surface snowmelt was well correlated with atmospheric indices in some regions. Notably, the decreasing surface snowmelt on the AIS was very likely linked with the enhancing summer Southern Annular Mode.
Determination of natural frequencies and mode shapes of a wind turbine rotor blade using Timoshenko beam elements
Authors: Stanoev Evgueni , Kusuma Chandrashekhara Sudhanva
Published: January 2019

Abstract. When simulating a wind turbine, the lowest eigenmodes of the rotor blades are
usually used to describe their elastic deformation in the frame of a
multi-body system. In this paper, a finite element beam model for the rotor
blades is proposed which is based on the transfer matrix method. Both static
and kinetic field matrices for the 3-D Timoshenko beam element are derived by
the numerical integration of the differential equations of motion using a
Runge–Kutta fourth-order procedure. In the general case, the beam reference
axis is at an arbitrary location in the cross section. The inertia term in
the motion differential equation is expressed using appropriate shape
functions for the Timoshenko beam. The kinetic field matrix is built by
numerical integration applied on the approximated inertia term. The beam
element stiffness and mass matrices are calculated by simple matrix
operations from both field matrices. The system stiffness and mass matrices
of the rotor blade model are assembled in the usual finite element manner in
a global coordinate system accounting for the structural twist angle and
possible pre-bending. The program developed for the above-mentioned
calculations and the final solution of the eigenvalue problem is accomplished
using MuPAD, a symbolic math toolbox in
MATLAB®. The natural frequencies calculated
using generic rotor blade data are compared with the results proposed from
the FAST and ADAMS software.