bluuebunny/crossref_metadata_2025 huggingface dataset:
A Generic Tool for Generating and Assessing Problems Automatically using Spreadsheets
Authors: Rafart Serra Maria Assumpció , Bikfalvi Andrea , Soler Masó Josep , Poch Garcia Jordi
Published: October 2018

A myriad of higher education degrees including science, engineering, business and economics could integrate activities using spreadsheet into the teaching-learning process. In the present article, we aim to introduce and describe a new tool that generates, individually assigns, corrects, provides feed-back and grades exercises and activities using spreadsheets all completely automatically. The system’s versatility means it can be applied in a range of areas of knowledge and subjects including mathematics, statistics, physics, accounting and economics, among others. It is usable for both formative and summative assessment based on students’ answers, providing them with the corresponding feed-back and/or the resultant grades. The proposed solution has been developed and implemented at the University of Girona (Spain) and forms part a wider family of tools that aim to contribute to the continuous improvement of higher education.
The Grading Multiple Choice Tests System via Mobile Phone using Image Processing Technique
Authors: Yimyam Worawut , Ketcham Mahasak
Published: October 2018

Grading devices are expensive causing budget waste, in addition some are difficult to use. Therefore, an objective test grading system via Android mobile phone was developed to save cost and time in grading. The system uses image processing technique developed by Java. A camera on a mobile phone was used to capture the edge of answers and an equation of geometric simulation of digital camera sensor was applied to identify answers selected from calculation of pixel intensity in real time. The objective test grading system via Android mobile phone can work effectively and accurately more than 95%.
Teaching Quality Evaluation and Scheme Prediction Model Based on Improved Decision Tree Algorithm
Authors: Jia Sujuan , Pang Yajing
Published: October 2018

Vast data in the higher education system are used to analyse and evaluate the teaching quality, so that the key factors that affect the quality of teaching can be predicted. Besides, the learner’s personalized behaviour can also become the data source for teaching result prediction. This paper proposes a decision tree model by taking the teaching quality data and the statistical analysis results of the learn-er’s personalized behaviour as inputs. This model was based on the improved C4.5 decision tree algorithm, which used the FAYYAD boundary point decision theorem for effectively reducing the computation time to the most threshold. In this algorithm, the iterative analysis mechanism was introduced in combination with the data change of the learner’s personalized behaviour, so as to dynamically adjust the final teaching evaluation result. Finally, according to the actual statisti-cal data of one academic year, the teaching quality evaluation was effectively completed and the direction of future teaching prediction was proposed.
An Internet of Things System Based on Device-to-Device Communication Technology and Radio-Frequency Identification
Authors: Huang Cheng , Lv Yongbo
Published: October 2018

This paper aims to build a mobile communication system suitable for different application scenarios of the Internet of Things (IoT). For this purpose, an IoT system was developed based on device-to-device (D2D) communication technology and radio-frequency identification (RFID). The D2D-RFID-based IoT system combines the merits of mobile communication (e.g. 4G) and the RFID. The analysis shows that the proposed system boasts good mobility, stable transmission, short time delay, fixed IP, and no need of a central server. The research findings have a great application potential in different IoT scenarios.
A Review of Human Motion Monitoring Methods using Wearable Sensors
Authors: Tu Yaqing , Liu Linfeng , Li Ming , Chen Peng , Mao Yuwen
Published: October 2018

Human motion monitoring with wearable devices has become a hot research topic in the field of smart wearable devices. In this paper, the principles and historical development of human motion monitoring with wearable devices are analyzed and reviewed, respectively. Specifically, the current situation of human motion monitoring with wearable devices based on acceleration sensors is analyzed first. Then the existing problems and the future developing trends of research on human motion monitoring methods are summarized. Finally, the prospects of the research on of human motion monitoring method with wearable devices are discussed.
A New Method for Reliability Evaluation of Wireless Sensor Networks Based on Fuzzy Neural Network
Authors: Xu Jianjun
Published: October 2018

In this paper, a reliability evaluation model based on fuzzy neural network is proposed to evaluate the reliability of wireless sensor networks without a unified standard. Firstly, the reliability is analyzed from the point of view of topology structure, protocol stack structure and reliability mechanism of wireless sensor network, and the performance indexes that affect the reliability are extracted. Secondly, some performance indexes are screened out, and the standard value matrix of reliability evaluation for index fuzzy quantization is established. The sample data is generated by interpolation, and the reliability evaluation model based on fuzzy neural network is established. The neural network model takes the selected index values as input, and outputs are the reliability of the wireless sensor network. The simulation results show that the evaluation model is basically consistent with the actual situation, and it can evaluate the wireless sensor network from the system level.
Loss of Canonical Notch Signaling Affects Multiple Steps in NK Cell Development in Mice
Authors: Chaves Patricia , Zriwil Alya , Wittmann Lilian , Boukarabila Hanane , Peitzsch Claudia , Jacobsen Sten Eirik W. , Sitnicka Ewa
Published: October 2018

Within the hematopoietic system, the Notch pathway is critical for promoting thymic T cell development and suppressing the B and myeloid lineage fates; however, its impact on NK lymphopoiesis is less understood. To study the role of Notch during NK cell development in vivo, we investigated different NK cell compartments and function in Rbp-Jkfl/flVav-Cretg/+ mice, in which Rbp-Jk, the major transcriptional effector of canonical Notch signaling, was specifically deleted in all hematopoietic cells. Peripheral conventional cytotoxic NK cells in Rbp-Jk–deleted mice were significantly reduced and had an activated phenotype. Furthermore, the pool of early NK cell progenitors in the bone marrow was decreased, whereas immature NK cells were increased, leading to a block in NK cell maturation. These changes were cell intrinsic as the hematopoietic chimeras generated after transplantation of Rbp-Jk–deficient bone marrow cells had the same NK cell phenotype as the Rbp-Jk–deleted donor mice, whereas the wild-type competitors did not. The expression of several crucial NK cell regulatory pathways was significantly altered after Rbp-Jk deletion. Together, these results demonstrate the involvement of canonical Notch signaling in regulation of multiple stages of NK cell development.
Discordant interpretation of serial bone mineral density measurements by dual-energy X-ray absorptiometry using vendor's and institutional least significant changes: Serious impact on decision-making
Authors: Fatima Nosheen , Zaman Maseeh , Saleem Sadaf , Hameed Noureen , Bano Jamila
Published: October 2018

Meaningful change in bone mineral density (BMD) should be equal or higher than institutional least significant change (LSC). But some facilities use vendor's LSC which is discouraged by International Society for Clinical Densitometry (ISCD). The aim of this study was to find the impact of scan interpretation upon interval BMD changes using vendors and institutional LSCs. This prospective study was conducted at Joint Commission International-accredited facility of Pakistan from April–June 2017 using Hologic Discovery-A scanner. As per ISCD recommendations, precision error and LSC of two technologists were measured. Serial BMD changes such as deterioration or improvement interpreted based on vendor's and institutional LSCs were compared. Serial BMD changes in 102 patients were included, having a mean age, male:female ratio, and mean body mass index of 63 years, 94%:06%, and 29.274 kg/m2, respectively. Mean menopausal age was 47 years and mean duration between two dual X-ray absorptiometry (DXA) studies was 3 years. BMD changes over hip were found significant in 55% and 53% cases against vendor's and institutional LSCs, respectively (nonsignificant discordance in 2%). BMD changes using vendor's and institutional LSCs were found significant over L1-4 (62% vs. 46%; discordance: 14%) and distal forearm (77% vs. 35%; discordance: 41%), respectively. Interpretations based on vendor's LSCs revealed significantly overestimated deterioration over forearm and improvement over L1-4 BMD values. We conclude that vendor's provided LSC for interpretation of serial DXA is misleading and has a significant negative impact upon patients' management. Every DXA facility must use its own LSC as per ISCD guidelines. Furthermore, ISCD must consider publishing cutoff values for LSC for distal forearm measurement.
Prognostic factors in breast cancer patients evaluated by positron-emission tomography/computed tomography before neoadjuvant chemotherapy
Authors: Farrugia Mark , Wen Sinjen , Jacobson Geraldine , Salkeni Mohamad
Published: October 2018

Neoadjuvant chemotherapy (NAC) is a significant modality in breast cancer therapy. We sought to characterize prognostic factors in patients scheduled for NAC who had a pretreatment positron-emission tomography paired with diagnostic quality contrast-enhanced computed tomography (CT) (positron-emission tomography/CT [PET/CT]). A total of 118 breast cancer patients were analyzed through chart review who underwent pretreatment PET/CT imaging and received NAC from 2008 to 2014. We collected information on molecular markers, PET/CT, pathologic complete response (pCR), survival, and disease status. Pretreatment standard uptake value (SUV) max of the primary breast tumor showed no relationship to pCR; however, there was a statistically significant relationship with relapse-free survival (RFS) using univariate cox regression (P = 0.03, odds ratio (OR) = 1.06 [1.01–1.12]) with comparable findings observed with overall survival (OS). Multivariate analysis revealed SUV max to be significantly correlated with shortened OS (P = 0.022, OR = 1.08 [1.01–1.16]), with a similar trend reported for RFS. By pathological subtype, this correlation was the strongest within hormone receptor (HR+)/human epidermal growth factor receptor 2 (HER2−) tumors. In addition, Kaplan–Meier estimates demonstrated a significant difference between the RFS of triple-negative tumors and HER2 positive tumors (P = 0.001). Interestingly, within this cohort, multivariate Cox regression analysis showed HER2 positivity to be associated with favorable outcome (P = 0.04, HR = 0.22 [0.05–0.94]). These findings demonstrate a significant association between SUV max of HR+/HER2−− tumors and relapse-free and OS. Furthermore, highlighted here is the favorable survival in the once classically aggressive HER2+ breast cancer subgroup.
The Quotient Problem for Entire Functions
Authors: Guo Ji
Published: October 2018

Let $\{\mathbf{F}(n)\}_{n\in \mathbb{N}}$ and $\{\mathbf{G}(n)\}_{n\in \mathbb{N}}$ be linear recurrence sequences. It is a well-known Diophantine problem to determine the finiteness of the set ${\mathcal{N}}$ of natural numbers such that their ratio $\mathbf{F}(n)/\mathbf{G}(n)$ is an integer. In this paper we study an analogue of such a divisibility problem in the complex situation. Namely, we are concerned with the divisibility problem (in the sense of complex entire functions) for two sequences $F(n)=a_{0}+a_{1}f_{1}^{n}+\cdots +a_{l}f_{l}^{n}$ and $G(n)=b_{0}+b_{1}g_{1}^{n}+\cdots +b_{m}g_{m}^{n}$, where the $f_{i}$ and $g_{j}$ are nonconstant entire functions and the $a_{i}$ and $b_{j}$ are non-zero constants except that $a_{0}$ can be zero. We will show that the set ${\mathcal{N}}$ of natural numbers such that $F(n)/G(n)$ is an entire function is finite under the assumption that $f_{1}^{i_{1}}\cdots f_{l}^{i_{l}}g_{1}^{j_{1}}\cdots g_{m}^{j_{m}}$ is not constant for any non-trivial index set $(i_{1},\ldots ,i_{l},j_{1},\ldots ,j_{m})\in \mathbb{Z}^{l+m}$.
Efectos sobre el IMC de un programa de promoción de hábitos saludables para adolescentes y sus padres
Authors: Chávez Montes de Oca Virginia , Lerma Partida Silvia , Luna Vázquez Fabiola , Carrasco Ponce Berenice , Jiménez Rivera Paul
Published: October 2018

Introducción: La obesidad y el sobrepeso representan un problema de salud pública. Su alta prevalencia y las consecuencias biopsicosociales negativas del exceso de peso en adolescentes resaltan la necesidad de un tratamiento efectivo. La intervención mediante la promoción de hábitos saludables es una estrategia para mejorar esta condición. El objetivo de este estudio fue desarrollar un programa de hábitos saludables para adolescentes y sus padres, buscando cambios en el índice de masa corporal de los adolescentes antes y después de aplicar el programa.

Material y Método: Se realizó un estudio longitudinal, prospectivo, cuasi-experimental y correlacional, con muestreo no probabilístico, mediante un programa nutriológico, psicológico, físico y familiar en el que participaron adolescentes entre 12 y 15 años de edad así como a sus padres.

Resultados: Se observó una diferencia en el índice de masa corporal de los adolescentes antes y después de la asistencia al programa.

Conclusiones: En este estudio se pudo demostrar que tomar en cuenta los aspectos globales de nutrición, psicológicos, actividad física y familiar, es una solución efectiva para este importante problema de salud. 
Reincidencia y factores psicológicos en jóvenes con conductas de maltrato hacia sus progenitores
Authors: Maroto Méndez Zulay , Cortés Tomás Maria Teresa Teresa
Published: October 2018

El estudio de la reincidencia y las variables con las que se relaciona es importante de cara a minimizar la nueva comisión de conductas delictivas. Detectando aquellas variables relacionadas con el aumento de la reincidencia delictiva, se pueden perfeccionar los métodos de intervención utilizados para reducir la tasa de reincidencia sobre este tipo de conductas. En el caso de los jóvenes infractores este estudio requiere de una importancia considerable de cara a no consolidar un estilo de vida delictivo en el adolescente, que perdure durante la etapa adulta. En España son numerosas las investigaciones acerca de la reincidencia delictiva en menores. Sin embargo, en el estudio de la violencia filio-parental pocas son las investigaciones realizadas de cara a detectar las variables que correlacionan con la reincidencia. El presente estudio trata de conocer los índices de reincidencia en jóvenes que han cometido delitos de violencia filio-parental y relacionar estas reincidencias con las variables psicológicas halladas en la bibliografía sobre reincidencia en menores. Para ello se seleccionó a 72 menores que habían cumplido una medida judicial por un delito de maltrato familiar y se les realizó el pase de varios instrumentos de evaluación. Los resultados indicaron que las variables emocionabilidad, liderazgo, retraimiento social, tolerancia a la frustración, manejo del enfado, locus de control, habilidades sociales, estrategias de resolución de problemas y presencia de trastornos mentales se relacionaban significativamente con la reincidencia. Estos resultados se consideran importantes en aras a mejorar los programas de intervención en jóvenes con conductas de maltrato hacia sus progenitores.
Coronary age, based on coronary calcium measurement, is increased in patients with morbid obesity
Authors: Lemanowicz Adam , Białecki Marcin , Leszczyński Waldemar , Hawrył Mateusz
Published: October 2018

Purpose

Obesity is a well-known of risk factor for atherosclerosis. However, recently an “obesity paradox” has been discussed, which is considered as a protective effect of obesity on the development coronary artery disease (CAD). An aim of the study was to investigate the risk of CAD in morbidly obese patients using coronary artery calcium measurement.

Material and methods

Fifty-one patients with morbid obesity (BMI ≥ 40 kg/m2) and thirty controls were scanned to determine the amount of coronary artery calcification (CAC), which was expressed as calcium score (CS) and coronary age (CA). The control group consisted of patients scanned for the clinical suspicion of CAD, who did not fulfil the criteria of obesity.

Results

Mean BMI of obese patients and controls was 47.3 and 26.5, respectively (p < 0.0001). Arterial hypertension, dyslipidaemia, and smoking were more frequent in the control group than in the obesity group (p < 0.02). The prevalence of CAC was higher in the obesity group (53% vs. 23%, p < 0.01). The groups did not differ regarding CS and CA. However, the difference between coronary age and metrical age was higher in obese patients than in controls (+5.6 vs. –4.8 years, respectively, p < 0.005).

Conclusions

Patients with morbid obesity present an increased risk of CAD that is reflected by the difference between their coronary age and metrical age.
Tropospheric NO2, SO2, and HCHO over the East China Sea, using ship-based MAX-DOAS observations and comparison with OMI and OMPS satellite data
Authors: Tan Wei , Liu Cheng , Wang Shanshan , Xing Chengzhi , Su Wenjing , Zhang Chengxin , Xia Congzi , Liu Haoran , Cai Zhaonan , Liu Jianguo
Published: October 2018

Abstract. In this study, ship-based multi-axis differential optical
absorption spectroscopy (MAX-DOAS) measurements were performed in the East
China Sea (ECS) area in June 2017. The tropospheric slant column densities
(SCDs) of nitrogen dioxide (NO2), sulfur dioxide (SO2), and
formaldehyde (HCHO) were retrieved from the measured spectra using the
differential optical absorption spectroscopy (DOAS) technique. Using the
simple geometric approach, the SCDs of different trace gases observed at a
15∘ elevation angle were adopted to convert into tropospheric
vertical column densities (VCDs). During this campaign, the averaged VCDs of
NO2, SO2, and HCHO in the marine environment over the ECS area are 6.50×1015, 4.28×1015, and 7.39×1015 molec cm−2, respectively. In
addition, the ship-based MAX-DOAS trace gas VCDs were compared with
satellite observations of the Ozone Monitoring Instrument (OMI) and Ozone Mapping
and Profiler Suite (OMPS). The daily OMI NO2 VCDs agreed well with
ship-based MAX-DOAS measurements showing the correlation coefficient R of
0.83. In addition, the good agreements of SO2 and HCHO VCDs between the OMPS
satellite and ship-based MAX-DOAS observations were also found, with
correlation coefficients R of 0.76 and 0.69. The vertical profiles of these
trace gases are achieved from the measured differential slant column
densities (DSCDs) at different elevation angles using the optimal estimation
method. The retrieved profiles displayed the typical vertical distribution
characteristics, which exhibit low concentrations of <3,
<3, and <2 ppbv for NO2, SO2, and HCHO in a clean
area of the marine boundary layer far from coast of the Yangtze River Delta
(YRD) continental region. Interestingly, elevated SO2 concentrations can
be observed intermittently along the ship routes, which is mainly attributed
to the vicinal ship emissions in the view of the MAX-DOAS measurements.
Combined with the on-board ozone lidar measurements, the ozone (O3)
formation was discussed with the vertical profile of the HCHO∕NO2 ratio,
which is sensitive to increases in NO2 concentration. This study
provided further understanding of the main air pollutants in the marine
boundary layer of the ECS area and also benefited the formulation of policies
regulating the shipping emissions in such costal areas like the YRD region.
A comprehensive organic nitrate chemistry: insights into the lifetime of atmospheric organic nitrates
Authors: Zare Azimeh , Romer Paul S. , Nguyen Tran , Keutsch Frank N. , Skog Kate , Cohen Ronald C.
Published: October 2018

Abstract. Organic nitrate chemistry is the primary control over the lifetime of
nitrogen oxides (NOx) in rural and remote continental
locations. As NOx emissions decrease, organic nitrate
chemistry becomes increasingly important to urban air quality. However, the
lifetime of individual organic nitrates and the reactions that lead to their
production and removal remain relatively poorly constrained, causing organic
nitrates to be poorly represented by models. Guided by recent laboratory and
field studies, we developed a detailed gas-phase chemical mechanism
representing most of the important individual organic nitrates. We use this
mechanism within the Weather Research and Forecasting (WRF) model coupled
with Chemistry (WRF-Chem) to describe
the role of organic nitrates in nitrogen oxide chemistry and in comparisons
to observations. We find the daytime lifetime of total organic nitrates with
respect to all loss mechanisms to be 2.6 h in the model. This is consistent
with analyses of observations at a rural site in central Alabama during the
Southern Oxidant and Aerosol Study (SOAS) in summer 2013. The lifetime of the
first-generation organic nitrates is ∼2 h versus the 3.2 h lifetime
of secondary nitrates produced by oxidation of the first-generation nitrates.
The different generations are subject to different losses, with dry
deposition to the surface being the dominant loss process for the
second-generation organic nitrates and chemical loss being dominant for the
first-generation organic nitrates. Removal by hydrolysis
is found to be responsible for the loss of ∼30  % of the total
organic nitrate pool.
Simulating the influence of primary biological aerosol particles on clouds by heterogeneous ice nucleation
Authors: Hummel Matthias , Hoose Corinna , Pummer Bernhard , Schaupp Caroline , Fröhlich-Nowoisky Janine , Möhler Ottmar
Published: October 2018

Abstract. Primary ice formation,
which is an important process for mixed-phase clouds with an impact on their
lifetime, radiative balance, and hence the climate, strongly depends on the
availability of ice-nucleating particles (INPs). Supercooled droplets within
these clouds remain liquid until an INP immersed in or colliding with the
droplet reaches its activation temperature. Only a few aerosol particles are
acting as INPs and the freezing efficiency varies among them. Thus, the
fraction of supercooled water in the cloud depends on the specific properties
and concentrations of the INPs. Primary biological aerosol particles (PBAPs)
have been identified as very efficient INPs at high subzero temperatures, but
their very low atmospheric concentrations make it difficult to quantify their
impact on clouds. Here we use the regional atmospheric model COSMO–ART to simulate the
heterogeneous ice nucleation by PBAPs during a 1-week case study on a domain
covering Europe. We focus on three highly ice-nucleation-active PBAP species,
Pseudomonas syringae bacteria cells and spores from the fungi
Cladosporium sp. and Mortierella alpina. PBAP emissions are
parameterized in order to represent the entirety of bacteria and fungal
spores in the atmosphere. Thus, only parts of the simulated PBAPs are assumed
to act as INPs. The ice nucleation parameterizations are specific for the
three selected species and are based on a deterministic approach. The PBAP
concentrations simulated in this study are within the range of previously
reported results from other modeling studies and atmospheric measurements.
Two regimes of PBAP INP concentrations are identified: a temperature-limited
and a PBAP-limited regime, which occur at temperatures above and below a
maximal concentration at around −10 ∘C, respectively. In an
ensemble of control and disturbed simulations, the change in the average ice
crystal concentration by biological INPs is not statistically significant,
suggesting that PBAPs have no significant influence on the average state of
the cloud ice phase. However, if the cloud top temperature is below −15 ∘C, PBAP can influence the cloud ice phase and produce ice
crystals in the absence of other INPs. Nevertheless, the number of produced
ice crystals is very low and it has no influence on the modeled number of
cloud droplets and hence the cloud structure.
Combining cloud radar and radar wind profiler for a value added estimate of vertical air motion and particle terminal velocity within clouds
Authors: Radenz Martin , Bühl Johannes , Lehmann Volker , Görsdorf Ulrich , Leinweber Ronny
Published: October 2018

Abstract. Vertical-stare observations from a 482 MHz radar wind profiler and a
35 GHz cloud radar are combined on the level of individual Doppler
spectra to measure vertical air motions in clear air, clouds and
precipitation. For this purpose, a separation algorithm is proposed to remove
the influence of falling particles from the wind profiler Doppler spectra and
to calculate the terminal fall velocity of hydrometeors. The remaining error
of both vertical air motion and terminal fall velocity is estimated to be
better than 0.1 m s−1 using numerical simulations. This
combination of instruments allows direct measurements of in-cloud vertical
air velocity and particle terminal fall velocity by means of ground-based
remote sensing. The possibility of providing a profile every 10 s
with a height resolution of <100 m allows further insight into the
process scale of in-cloud dynamics. The results of the separation algorithm
are illustrated by two case studies, the first covering a deep frontal cloud
and the second featuring a shallow mixed-phase cloud.
Variations of the 630.0 nm airglow emission with meridional neutral wind and neutral temperature around midnight
Authors: Chiang Chih-Yu , Tam Sunny Wing-Yee , Chang Tzu-Fang
Published: October 2018

Abstract. The ISUAL payload onboard the FORMOSAT-2 satellite has often observed airglow
bright spots around midnight at equatorial latitudes. Such features had been
suggested as the signature of the thermospheric midnight temperature maximum
(MTM) effect, which was associated with temperature and meridional neutral
winds. This study investigates the influence of neutral temperature and
meridional neutral wind on the volume emission rates of the 630.0 nm
nightglow. We utilize the SAMI2 model to simulate the charged and neutral
species at the 630.0 nm nightglow emission layer under different
temperatures with and without the effect of neutral wind. The results show
that the neutral wind is more efficient than temperature variation in
affecting the nightglow emission rates. For example, based on our estimation,
it would require a temperature change of 145 K to produce a change in the
integrated emission rate by 9.8 km-photons cm−3 s−1, while it only
needs the neutral wind velocity to change by 1.85 m−1 s−1 to
cause the same change in the integrated emission rate. However, the emission
rate features a local maximum in its variation with the temperature. Two
kinds of tendencies can be seen regarding the temperature that corresponds to
the turning point, which is named the turning temperature (Tt) in
this study: firstly, Tt decreases with the emission rate for the
same altitude; secondly, for approximately the same emission rate,
Tt increases with the altitude.
Factors controlling the community structure of picoplankton in contrasting marine environments
Authors: Otero-Ferrer Jose Luis , Cermeño Pedro , Bode Antonio , Fernández-Castro Bieito , Gasol Josep M. , Morán Xosé Anxelu G. , Marañon Emilio , Moreira-Coello Victor , Varela Marta M. , Villamaña Marina , Mouriño-Carballido Beatriz
Published: October 2018

Abstract. The
effect of inorganic nutrients on planktonic assemblages has traditionally
relied on concentrations rather than estimates of nutrient supply. We
combined a novel dataset of hydrographic properties, turbulent mixing,
nutrient concentration, and picoplankton community composition with the aims
of (i) quantifying the role of temperature, light, and nitrate fluxes as
factors controlling the distribution of autotrophic and heterotrophic
picoplankton subgroups, as determined by flow cytometry, and (ii) describing
the ecological niches of the various components of the picoplankton
community. Data were collected at 97 stations in the Atlantic Ocean,
including tropical and subtropical open-ocean waters, the northwestern
Mediterranean Sea, and the Galician coastal upwelling system of the northwest
Iberian Peninsula. A generalized additive model (GAM) approach was used to
predict depth-integrated biomass of each picoplankton subgroup based on three
niche predictors: sea surface temperature, averaged daily surface irradiance,
and the transport of nitrate into the euphotic zone, through both diffusion
and advection. In addition, niche overlap among different picoplankton
subgroups was computed using nonparametric kernel density functions.
Temperature and nitrate supply were more relevant than light in predicting
the biomass of most picoplankton subgroups, except for
Prochlorococcus and low-nucleic-acid (LNA) prokaryotes, for which irradiance also played a
significant role. Nitrate supply was the only factor that allowed the
distinction among the ecological niches of all autotrophic and heterotrophic
picoplankton subgroups. Prochlorococcus and LNA prokaryotes were
more abundant in warmer waters (>20 ∘C) where the nitrate fluxes
were low, whereas Synechococcus and high-nucleic-acid (HNA)
prokaryotes prevailed mainly in cooler environments characterized by
intermediate or high levels of nitrate supply. Finally, the niche of
picoeukaryotes was defined by low temperatures and high nitrate supply. These
results support the key role of nitrate supply, as it not only promotes the
growth of large phytoplankton, but it also controls the structure of marine
picoplankton communities.
Coral reef carbonate budgets and ecological drivers in the central Red Sea – a naturally high temperature and high total alkalinity environment
Authors: Roik Anna , Röthig Till , Pogoreutz Claudia , Saderne Vincent , Voolstra Christian R.
Published: October 2018

Abstract. The structural framework provided by corals is crucial for reef
ecosystem function and services, but high seawater temperatures can be
detrimental to the calcification capacity of reef-building organisms. The Red
Sea is very warm, but total alkalinity (TA) is naturally high and
beneficial for reef accretion. To date, we know little about how such
detrimental and beneficial abiotic factors affect each other and the balance
between calcification and erosion on Red Sea coral reefs, i.e., overall
reef growth, in this unique ocean basin. To provide estimates of present-day
reef growth dynamics in the central Red Sea, we measured two metrics of reef
growth, i.e., in situ net-accretion/-erosion rates (Gnet)
determined by deployment of limestone blocks and ecosystem-scale carbonate
budgets (Gbudget), along a cross-shelf gradient (25 km,
encompassing nearshore, midshore, and offshore reefs). Along this gradient, we assessed
multiple abiotic (i.e., temperature, salinity, diurnal pH fluctuation,
inorganic nutrients, and TA) and biotic (i.e., calcifier and epilithic
bioeroder communities) variables. Both reef growth metrics revealed similar
patterns from nearshore to offshore: net-erosive, neutral, and net-accretion
states. The average cross-shelf Gbudget was 0.66 kg
CaCO3 m−2 yr−1, with the highest budget of 2.44 kg
CaCO3 m−2 yr−1 measured in the offshore reef. These
data are comparable to the contemporary Gbudgets from the western
Atlantic and Indian oceans, but lie well below “optimal reef production”
(5–10 kg CaCO3 m−2 yr−1) and below maxima recently
recorded in remote high coral cover reef sites. However, the erosive forces
observed in the Red Sea nearshore reef contributed less than observed
elsewhere. A higher TA accompanied reef growth across the shelf gradient,
whereas stronger diurnal pH fluctuations were associated with negative
carbonate budgets. Noteworthy for this oligotrophic region was the positive effect of
phosphate, which is a central micronutrient for reef building corals. While
parrotfish contributed substantially to bioerosion, our dataset also
highlights coralline algae as important local reef builders. Altogether, our
study establishes a baseline for reef growth in the central Red Sea that
should be useful in assessing trajectories of reef growth capacity under
current and future ocean scenarios.
A model of mercury cycling and isotopic fractionation in the ocean
Authors: Archer David E. , Blum Joel D.
Published: October 2018

Abstract. Mercury speciation and isotopic fractionation processes
have been incorporated into the HAMOCC offline ocean tracer advection code.
The model is fast enough to allow a wide exploration of the sensitivity of
the Hg cycle in the oceans, and of factors controlling human exposure to
monomethyl-Hg through the consumption of fish. Vertical particle transport
of Hg appears to play a discernable role in setting present-day Hg
distributions, which we surmise by the fact that in simulations without
particle transport, the high present-day Hg deposition rate leads to an Hg
maximum at the sea surface, rather than a subsurface maximum as observed. Hg
particle transport has a relatively small impact on anthropogenic Hg uptake,
but it sequesters Hg deeper in the water column, so that excess Hg is
retained in the model ocean for a longer period of time after anthropogenic
Hg deposition is stopped. Among 10 rate constants in the model, steady-state
Hg concentrations are most sensitive to reactions that are sources or sinks
of Hg(0), the evasion of which to the atmosphere is the dominant sink term
in the surface ocean. Isotopic fractionations in the interconversion
reactions are most strongly expressed, in the isotopic signatures of
dissolved Hg, in reactions that involve the dominant dissolved species,
Hg(II), including mass independent fractionation during Hg photoreduction.
The Δ199Hg of MMHg in the model, subject to photoreduction
fractionation, reproduces the Δ199Hg of fish in the upper 1000 m of the ocean, while the impact of anthropogenic Hg deposition on Hg
isotope ratios is essentially negligible.
Manganese incorporation in living (stained) benthic foraminiferal shells: a bathymetric and in-sediment study in the Gulf of Lions (NW Mediterranean)
Authors: Ní Fhlaithearta Shauna , Fontanier Christophe , Jorissen Frans , Mouret Aurélia , Dueñas-Bohórquez Adriana , Anschutz Pierre , Fricker Mattias B. , Günther Detlef , de Lange Gert J. , Reichart Gert-Jan
Published: October 2018

Abstract. Manganese geochemistry in deep-sea sediments is known to vary
greatly over the first few centimeters, which overlaps the in-sediment
depth habitats of several benthic foraminiferal species. Here we investigated
manganese incorporation in benthic foraminiferal shell carbonate across a
six-station depth transect in the Gulf of Lions, NW Mediterranean, to unravel
the impacts of foraminiferal ecology and Mn pore water geochemistry. Over
this transect water depth increases from 350 to 1987 m, while temperature
(∼13 ∘C) and salinity (∼38.5) remained relatively
constant. Manganese concentrations in the tests of living (rose bengal
stained) benthic foraminiferal specimens of Hoeglundina elegans,
Melonis barleeanus, Uvigerina mediterranea, and
Uvigerina peregrina were measured using laser ablation inductively
coupled mass spectrometry (laser ablation ICP-MS). Pore water manganese
concentrations show a decrease from shallow to deeper waters, which
corresponds to a generally decreasing organic-matter flux with water depth.
Differences in organic-matter loading at the sediment–water interface affects
oxygen penetration depth into the sediment and hence Mn pore water profiles.
Mn ∕ Ca values for the investigated foraminiferal species reflect pore
water geochemistry and species-specific microhabitat in the sediment. The
observed degree of variability within a single species is in line with known
ranges in depth habitat and gradients in redox conditions. Both the Mn ∕ Ca
ratio and interspecific variability hence reflect past Mn cycling and
related early diagenetic processes within the sediment, making this a
potential tool for bottom-water oxygenation and organic-matter fluxes.
Dynamics of both in-sediment foraminiferal depth habitats and Mn cycling,
however, limit the application of such a proxy to settings with relatively
stable environmental conditions.
Vivianite formation in methane-rich deep-sea sediments from the South China Sea
Authors: Liu Jiarui , Izon Gareth , Wang Jiasheng , Antler Gilad , Wang Zhou , Zhao Jie , Egger Matthias
Published: October 2018

Abstract. Phosphorus is often invoked as the ultimate limiting nutrient,
modulating primary productivity on geological timescales. Consequently, along
with nitrogen, phosphorus bioavailability exerts a fundamental control on
organic carbon production, linking all the biogeochemical cycles across the
Earth system. Unlike nitrogen that can be microbially fixed from an
essentially infinite atmospheric reservoir, phosphorus availability is
dictated by the interplay between its sources and sinks. While authigenic
apatite formation has received considerable attention as the dominant
sedimentary phosphorus sink, the quantitative importance of reduced
iron-phosphate minerals, such as vivianite, has only recently been
acknowledged, and their importance remains underexplored. Combining
microscopic and spectroscopic analyses of handpicked mineral aggregates with
sediment geochemical profiles, we characterize the distribution and
mineralogy of iron-phosphate minerals present in methane-rich sediments
recovered from the northern South China Sea. Here, we demonstrate that
vivianite authigenesis is pervasive in the iron-oxide-rich sediments below
the sulfate–methane transition zone (SMTZ). We hypothesize that the downward
migration of the SMTZ concentrated vivianite formation below the current
SMTZ. Our observations support recent findings from non-steady-state
post-glacial sedimentary successions, suggesting that iron reduction below
the SMTZ, probably driven by iron-mediated anaerobic oxidation of methane
(Fe-AOM), is coupled to phosphorus cycling on a much greater spatial scale
than previously assumed. Calculations reveal that vivianite acts as an
important burial phase for both iron and phosphorus below the SMTZ,
sequestering approximately half of the total reactive iron pool. By
extension, sedimentary vivianite formation could serve as a mineralogical
marker of Fe-AOM, signalling low-sulfate availability against methanogenic
and ferruginous backdrop. Given that similar conditions were likely present
throughout vast swathes of Earth's history, it is possible that Fe-AOM and
vivianite authigenesis may have modulated methane and phosphorus availability
on the early Earth, as well as during later periods of expanded marine oxygen
deficiency. A better understanding of vivianite authigenesis, therefore, is
fundamental to test long-standing hypotheses linking climate, atmospheric
chemistry and the evolution of the biosphere.
Fe(II) stability in seawater
Authors: Hopwood Mark J. , Santana-González Carolina , Gallego-Urrea Julian , Sanchez Nicolas , Achterberg Eric P. , Ardelan Murat V. , Gledhill Martha , González-Dávila Melchor , Hoffmann Linn , Leiknes Øystein , Santana-Casiano Juana Magdalena , Tsagaraki Tatiana M. , Turner David
Published: October 2018

Abstract. The speciation of dissolved iron (DFe) in the ocean is widely assumed to consist exclusively of Fe(III)-ligand complexes. Yet in most aqueous environments a poorly defined fraction of DFe also exists as Fe(II). Here we deploy flow injection analysis to measure in-situ Fe(II) concentrations during a series of mesocosm/microcosm experiments in coastal environments in addition to the decay rate of this Fe(II) when moved into the dark. During 5 mesocosm/microcosm experiments in Svalbard and Patagonia, where dissolved (0.2 µm) Fe and Fe(II) were quantified simultaneously, Fe(II) constituted 24–65 % of DFe suggesting that Fe(II) was a large fraction of the DFe pool. When this Fe(II) was allowed to decay in the dark, the vast majority of measured oxidation rate constants were retarded relative to calculated constants derived from ambient temperature, salinity, pH and dissolved O2. The oxidation rates of Fe(II) spikes added to Atlantic seawater more closely matched calculated rate constants. The difference between observed and theoretical decay rates in Svalbard and Patagonia was most pronounced at Fe(II) concentrations
The Copernicus Surface Velocity Platform drifter with Barometer and Reference Sensor for Temperature (SVP-BRST): Genesis, design, and initial results
Authors: Poli Paul , Lucas Marc , O'Carroll Anne , Le Menn Marc , David Arnaud , Corlett Gary K. , Blouch Pierre , Meldrum David , Merchant Christopher J. , Belbeoch Mathieu , Herklotz Kai
Published: October 2018

Abstract. To support calibration and validation of satellite Sea-Surface Temperature (SST) retrievals, over 60 High Resolution SST (HRSST) drifting buoys were deployed at sea between 2012 and 2017. Their data record is reviewed here. It is confirmed that sea-state and immersion depth play an important role in understanding the data collected by such buoys and that the SST sensors need adequate insulation. In addition, calibration verification of three recovered drifters suggests that the sensor drift is low, albeit negative at around −0.01 K/year. However, the statistical significance of these results is limited, and the calibration procedure could not be exactly reproduced, introducing additional uncertainties into this drift assessment. Based on lessons learnt from these initial buoys, a new-generation drifter was designed to serve calibration of SST retrievals by European Union's Copernicus satellites. The novel drifter includes an HRSST sensor calibrated by a metrology laboratory. The sensor includes a pressure probe to monitor immersion depth in calm water, and acquires SST data at 1 Hz over a 5-minute interval every hour. This enables the derivation of mean SST as well as several percentiles of the SST distribution. The HRSST sensor is calibrated with an uncertainty better than 0.01 K. Analysis of the data collected by two prototypes deployed in the Mediterranean Sea shows that the buoys are able to capture small-scale SST variations. These variations are found to be smaller when the sea-state is well-mixed, and when the buoys are located within eddy cores. This affects the drifter SST data representativeness, which is an aspect of importance for optimal use of these data.
Seasonal and interannual variability of water column properties along the Rottnest continental shelf, south-west Australia
Authors: Chen Miaoju , Pattiaratchi Charitha B. , Ghadouani Anas , Hanson Christine
Published: October 2018

Abstract. A multiyear, ocean glider dataset, obtained along a representative cross-shelf transect along the Rottnest continental shelf, south-west Australia, was used to characterise the seasonal and inter-annual variability of water column properties (temperature, salinity, and chlorophyll fluorescence distribution). All three variables showed distinct seasonal and inter-annual variations. Local and basin-scale ocean–atmosphere processes also affected the spatial distributions of the water column properties. The controlling influences for the variability were derived from (a) at the local scale, the Leeuwin Current and dense shelf water cascades (DSWC); and, (2) at the basin scale, the El Niño Southern Oscillation (ENSO). In spring and summer, shallow waters were well mixed due to strong wind mixing and the deeper waters (> 50 m) were vertically stratified in temperature that contributed to the formation of a subsurface chlorophyll maximum (SCM). With the onset of storms in late autumn, the water column was well mixed with the SCM absent. On the inner shelf, chlorophyll fluorescence concentrations were highest in autumn and winter; DSWCs were also the main physical feature during autumn and winter. Chlorophyll fluorescence concentration was higher closer to the sea bed than at the surface in spring, summer, and autumn. The seasonal patterns coincided with changes in the wind field (weaker winds in autumn) and air–sea fluxes (winter cooling and summer evaporation). Inter-annual variation was associated with ENSO events. Lower temperatures, higher salinity, and higher chlorophyll fluorescence (> 1 mg m−3) were associated with the El Niño event in 2010. During the strong La Niña event in 2011, temperatures increased (a marine heat wave), and salinity and chlorophyll fluorescence decreased (
Aluminium and base cation chemistry in dynamic acidification models – need for a reappraisal?
Authors: Gustafsson Jon Petter , Belyazid Salim , McGivney Eric , Löfgren Stefan
Published: October 2018

Abstract. Long-term simulations of the water composition in acid forest soils require
that accurate descriptions of aluminium and base cation chemistry are used.
Both weathering rates and soil nutrient availability depend on the
concentrations of Al3+, of H+, and of base cations
(Ca2+, Mg2+, Na+, and K+) .
Assessments of the acidification status and base cation availability will
depend on the model being used. Here we review in what ways different dynamic
soil chemistry models describe the processes governing aluminium and base
cation concentrations in the soil water. Furthermore, scenario simulations
with the HD-MINTEQ model are used to illustrate the difference between model
approaches. The results show that all investigated models provide the same
type of response to changes in input water chemistry. Still, for base cations
we show that the differences in the magnitude of the response may be
considerable depending on whether a cation-exchange equation (Gaines–Thomas,
Gapon) or an organic complexation model is used. The former approach, which
is used in many currently used models (e.g. MAGIC, ForSAFE), causes stronger
pH buffering over a relatively narrow pH range, as compared to
state-of-the-art models relying on more advanced descriptions in which
organic complexation is important (CHUM, HD-MINTEQ). As for aluminium, a
“fixed” gibbsite constant, as used in MAGIC, SMART/VSD, and ForSAFE, leads to
slightly more pH buffering than in the more advanced models that consider
both organic complexation and Al(OH)3(s) precipitation, but in this
case the effect is small. We conclude that the descriptions of acid–base
chemistry and base cation binding in models such as MAGIC, SMART/VSD, and
ForSAFE are only likely to work satisfactorily in a narrow pH range. If the
pH varies greatly over time, the use of modern organic complexation models is
preferred over cation-exchange equations.