bluuebunny/crossref_metadata_2025 huggingface dataset:
SHARP: A Spatially Higher-order, Relativistic Particle-in-cell Code
Authors: Shalaby Mohamad , Broderick Avery E. , Chang Philip , Pfrommer Christoph , Lamberts Astrid , Puchwein Ewald
Published: May 2017

Numerical heating in particle-in-cell (PIC) codes currently precludes the accurate simulation of cold, relativistic plasma over long periods, severely limiting their applications in astrophysical environments. We present a spatially higher-order accurate relativistic PIC algorithm in one spatial dimension, which conserves charge and momentum exactly. We utilize the smoothness implied by the usage of higher-order interpolation functions to achieve a spatially higher-order accurate algorithm (up to the fifth order). We validate our algorithm against several test problems—thermal stability of stationary plasma, stability of linear plasma waves, and two-stream instability in the relativistic and non-relativistic regimes. Comparing our simulations to exact solutions of the dispersion relations, we demonstrate that SHARP can quantitatively reproduce important kinetic features of the linear regime. Our simulations have a superior ability to control energy non-conservation and avoid numerical heating in comparison to common second-order schemes. We provide a natural definition for convergence of a general PIC algorithm: the complement of physical modes captured by the simulation, i.e., those that lie above the Poisson noise, must grow commensurately with the resolution. This implies that it is necessary to simultaneously increase the number of particles per cell and decrease the cell size. We demonstrate that traditional ways for testing for convergence fail, leading to plateauing of the energy error. This new PIC code enables us to faithfully study the long-term evolution of plasma problems that require absolute control of the energy and momentum conservation.
High-resolution Optical Spectroscopic Observations of Four Symbiotic Stars: AS 255, MWC 960, RW Hya, and StHα 32*
Authors: Pereira C. B. , Baella N. O. , Drake N. A. , Miranda L. F. , Roig F.
Published: May 2017

We report on the analysis of high-resolution optical spectra of four symbiotic stars: AS 255, MWC 960, RW Hya, and StHα32. We employ the local-thermodynamic-equilibrium model atmospheres of Kurucz and the spectral analysis code moog to analyze the spectra. The abundance of barium and carbon was derived using the spectral synthesis technique. The chemical composition of the atmospheres of AS 255 and MWC 960 show that they are metal-poor K giants with metallicities of −1.2 and −1.7 respectively. StHα32 is a CH star and also a low-metallicity object (−1.4). AS 255 and MWC 960 are yellow symbiotic stars and, like other previously studied yellow symbiotics, are s-process enriched. StHα32, like other CH stars, is also an s-process and carbon-enriched object. RW Hya has a metallicity of −0.64, a value in accordance with previous determinations, and is not s-process enriched. Based on its position in the 2MASS diagram, we suggest that RW Hya is at an intermediate position between yellow symbiotics and classical S-type symbiotics. We also discuss whether the dilution effect was the mechanism responsible for the absence of the s-process elements overabundance in RW Hya. The luminosity obtained for StHα32 is below the luminosity of the asymptotic giant branch (AGB) stars that started helium burning (via thermal pulses) and became self-enriched in neutron-capture elements. Therefore, its abundance peculiarities are due to mass transfer from the previous thermally pulsing AGB star (now the white dwarf) that was overabundant in s-process elements. For the stars AS 255 and MWC 960, the determination of their luminosities was not possible due to uncertainties in their distance and interstellar absorption. AS 255 and MWC 960 have a low galactic latitude and could be bulge stars or members of the inner halo population. The heavy-element abundance distribution of AS 255 and MWC 960 is similar to that of the other yellow symbiotics previously analyzed. Their abundance patterns follow that of the thick disk population for RW Hya and of the halo population for AS 255, MWC 960, and StHα32. We also determined the rotational velocities of these four symbiotic stars and compare our results with those of single field stars.
Whimper of a Bang: Documenting the Final Days of the Nearby Type Ia Supernova 2011fe
Authors: Shappee B. J. , Stanek K. Z. , Kochanek C. S. , Garnavich P. M.
Published: May 2017

Using the Hubble Space Telescope (HST) and the Large Binocular Telescope, we followed the evolution of the Type Ia supernova (SN Ia) 2011fe for an unprecedented 1840 days past B-band maximum light and over a factor of 7 million in flux. At 1840 days, the

4000

–

17000

Å quasi-bolometric luminosity is just (

420
±
20

)

L

⊙

. By measuring the late-time quasi-bolometric light curve, we present the first confident detection of 57Co decay in a SN Ia light curve and estimate a mass ratio of

log

(

57

Co

/

56

Co
)
=
−

1.59

−
0.07

+
0.06

. We do not have a clean detection of

55

Fe

, but find a limit of

55

Fe

/

57

Co
<
0.22

with 99% confidence. These abundance ratios provide unique constraints on the progenitor system because the central density of the exploding white dwarf(s) dictates these nucleosynthetic yields. The observed ratios strongly prefer the lower central densities of double-degenerate models (

55

Fe

/

57

Co
=
0.27

) over the higher central densities of near-Chandrasekhar-mass single-degenerate models (

55

Fe

/

57

Co
=
0.68

). However, additional theoretical studies predicting isotopic yields from a broader range of progenitor systems are motivated by these unique observations. We will continue to observe SN 2011fe for another ∼600 days with HST and possibly beyond.
Expériences muséales en Chine : douloureuses mémoires locales d’un départ forcé
Authors: Le Mentec Katiana
Published: May 2017

Résumé Le musée de Yunyang (Chongqing) expose la migration planifiée induite par le barrage des Trois Gorges qui a concerné un habitant du district sur six. Basée sur une enquête ethnographique d’un mois menée en 2014, l’analyse porte sur l’expression de la subjectivité des visiteurs locaux confrontés aux éléments de la scénographie relatifs aux familles déplacées dans des provinces lointaines. Leurs mémoires semblent s’être cristallisées autour de trois thématiques entrelacées : un départ forcé de la contrée ancestrale, la souffrance de ceux qui sont partis et la brisure du corps social.
HUMAN ACTION RECOGNITION USING A NEW SPARSE CODING APPROACH
Authors: Nikpour Mohsen , Mollaei Mohammad Reza Karami , Ghaderi Reza
Published: May 2017

Human action recognition (HAR) is a challenging problem because of the complexity and similarity in different actions. In recent years, many methods have been proposed for HAR. Sparse coding-based approaches have been widely used in this field. Also, many works have been done based on manifold learning theory. When the videos are similar but from different classes, their sparse codes may be similar and the actions might be classified mistakenly. In this paper, a multi-modal affine graph regularized sparse coding approach is proposed for solving this problem in HAR. At first, HOG3D, HOG/Hof and SURF3D descriptors were extracted from the action datasets, then the sparse codes have been obtained for each descriptor using the proposed method. The dictionary learning method used in this step has more discrimination power in respect to the traditional methods. Then, these codes are scored differently using SVM classifier and at last a Naïve Bayes leads to a final decision. Experiments on KTH, Weizmann and UCF Sport action datasets show that the proposed method can significantly outperform several previous methods in human action classification especially in real-world data.
COMPARISON OF VARIOUS MRI FAT SUPPRESSION TECHNIQUES ON A WATER-FAT PHANTOM AT 1.5 T
Authors: Wang Hui-Chun , Chen Po-Chou , Chou Chun-Hsiung , Shy Cherng-Gueih , Jao Jo-Chi
Published: May 2017

Nowadays, magnetic resonance imaging (MRI) has been widely applied for diagnosis of soft-tissue diseases. Most clinical MRI protocols use fat suppression (FS) methods to suppress fat signal, reduce chemical shift artifacts, and increase conspicuity of lesions. To understand the advantages, disadvantages, and clinical applications of the most commonly used FS methods is an important issue. The aim of this study was to evaluate FS performance of six FS methods on a fat-water phantom at 1.5[Formula: see text]T. The six MRI methods included iterative decomposition of water and fat with echo asymmetry and least squares estimation (IDEAL), short inversion time inversion recovery (STIR), and four chemical presaturation (Chem Presat) methods. The phantom was composed of homogeneous oil-in-water emulsions with various fat contents ranging from 0 to 100% in increments of 10%. The difference between the suppressed fat fractions (FS fractions) and the true fat fractions of the phantom was used as an index of FS performance. The correlations and levels of agreement (LOAs) between the FS fractions determined using each FS method and the true fat fractions of the phantom were analyzed. From the phantom study, it was found that FSE T2 FS, STIR and IDEAL could achieve more accurate FS fractions than the other three methods. The FS fractions determined using FSE T2 FS, STIR and IDEAL were in a good agreement. On the contrary, T2-weighted spin echo Chem Presat had the most inaccurate quantification of FS fractions among these six FS methods. Both the ranks of signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) of the phantom were IDEAL [Formula: see text] FSE T2 FS [Formula: see text] STIR. The FS performance of these six FS methods in clinical use needs further study.
Factors that impact Quality during the Transportation of Tomatoes
Authors: Negi Saurav , Anand Neeraj , Trivedi Shantanu
Published: May 2017

This paper examines the factors that impact the quality of tomatoes during the transportation through the supply chain. This is motivated by the criticality transportation in north India region. Primary data was collected through a survey using a questionnaire with responses from 140 transporters from the Himachal Pradesh and Uttarakhand states of India. The data were analyzed using factor analysis to identify the factors that are impacting the quality of tomatoes during the transportation stage. Based on the analysis, three factors were identified that impact quality: Operational, Preservation and Infrastructure. The identification of these factors will benefit the stakeholders involved in the process of decision-making, like the state government, food processing units, transporters, and the farmers. This will help us to understand the current status of transportation and related issues and challenges which enable them to make better planning and management to improve efficiency in the transportation stage of the supply chain.
Egocentric Landmark-Based Indoor Guidance System for the Visually Impaired
Authors: Yang Zhuorui , Ganz Aura
Published: May 2017

In this paper, we introduce an egocentric landmark-based guidance system that enables visually impaired users to interact with indoor environments. The user who wears Google Glasses will capture his surroundings within his field of view. Using this information, we provide the user an accurate landmark-based description of the environment including his relative distance and orientation to each landmark. To achieve this functionality, we developed a near real time accurate vision based localization algorithm. Since the users are visually impaired our algorithm accounts for captured images using Google Glasses that have severe blurriness, motion blurriness, low illumination intensity and crowd obstruction. We tested the algorithm performance in a 12,000 ft2 open indoor environment. When we have mint query images our algorithm obtains mean location accuracy within 5ft., mean orientation accuracy less than 2 degrees and reliability above 88%. After applying deformation effects to the query images such blurriness, motion blurriness and illumination changes, we observe that the reliability is above 75%.
A Proxy-Based Solution for Asynchronous Telemedical Systems
Authors: Rauti Sampsa , Lahtiranta Janne , Parisod Heidi , Hyrynsalmi Sami , Salanterä Sanna , Aromaa Minna Elisabeth , Smed Jouni , Leppänen Ville
Published: May 2017

Asynchronous telemedicine systems face many challenges related to information security as the patient's sensitive information and data on medicine dosage is transmitted over a network when monitoring patients and controlling asynchronous telemedical IoT devices. This information may be modified or spied on by a malicious adversary. To make asynchronous telemedicine systems more secure, the authors present a proxy-based solution against data modification and spying attacks in web-based telemedical applications. By obfuscating the executable code of a web application and by continuously dynamically changing obfuscation, the authors' solution makes it more difficult for a piece of malware to attack its target. They use a constructive research approach. They characterize the threat and present an outline of a proposed solution. The benefits and limitations of the proposed solution are discussed. Cyber-attacks targeted at the information related to patient's care are a serious threat in today's telemedicine. If disregarded, these attacks have negative implications on patient safety and quality of care.
Assessing Experimental Private Cloud Using Web of System Performance Model
Authors: Habbal Adib , Abdullah Siti Aminah , Mkpojiogu Emmanuel O.C. , Hassan Suhaidi , Benamar Nabil
Published: May 2017

Cloud computing has attracted the attention of educational and research institutions as a way to support modern trends in teaching and learning. This article describes the performance assessment of a private cloud within a university environment using the Web of System Performance (WOSP) model. A survey was carried out to measure the respondents' attitude towards the use of private cloud in which students and experts serve as sample. Testing was conducted by designing a virtual lab consisting of a number of virtual machines operated by a selected sample. The results showed that the usage of cloud computing in university has good perceived system performance judging from how it fares in the constituent parts of the WOSP model. Furthermore, the study revealed that usability and flexibility outperformed criterion like security. Moreover, several non-functional criteria outperformed functionality. In short, the knowledge and results presented from assessing a private cloud using WOSP model could be beneficial for users, designers and managers of private clouds especially in universities.
Defining and Evaluating A Novel Penalty Model for Managing Violations in the Cloud Computing
Authors: Maarouf Adil , El Qacimy Bouchra , Marzouk Abderrahim , Haqiq Abdelkrim
Published: May 2017

Managing and applying penalties has become a critical issue for Cloud Computing. In this paper, the authors investigate this issue and present the most frequently used definitions of service level agreements (SLA) penalty functions. They identify the characteristics of these functions by highlighting their strengths and weaknesses. They survey and analyze various penalty calculation and availability calculation methods of cloud providers. Then, they propose a Novel Penalty Model for computing the penalty cost of the violations and present formalization for the penalty concerned. They also propose a business model for cloud providers to manage their profit. An example application will be presented to demonstrate the effectiveness of the proposed model. Finally, the paper notes some challenges and future research directions.
Competitive Processors Allocation in 2D Mesh Connected Multicomputer Networks
Authors: Alsarhan Ayoub , Abdallah Emad Eddien Awad , Aljammal Ashraf H.
Published: May 2017

“Partitionable parallel machine” is an efficient computing system for executing parallel applications. In this paper, the problem of processors sharing among multiple users is addressed where users' requests are executed in a 2D mesh-connected multicomputer simultaneously. The problem is formulated as an oligopoly market where users compete to rent free processors. The system consists of self-interested users with different needs and utility functions. Each user engages in an auction with others to achieve their needs of processors. The most significant challenge for the users is how to select the optimal number of requested processors for winning the auction. A noncooperative game is used to obtain the optimal processors allocation for users. Game theory is employed to address this challenge for competing users. Nash equilibrium is considered as the solution of this game. The numerical results reveal the dynamics of distributed dynamic adaptation of processors sharing strategies.
Effects of Interaction on E-Learning Satisfaction and Outcome
Authors: Eom Sean , Laouar Mohamed Ridda
Published: May 2017

We have reviewed several e-learning empirical research studies that have investigated the effects of interaction on satisfaction and outcomes of e-learning, published between 2001 and 2010. Their conclusions seemed inconclusive, ranging from no relationships between interactions and two dependent variables (satisfaction and learning outcomes) to positive relationships. In-depth analyses of these empirical studies conducted by examining dependent and independent constructs and their indicators, research methods, and participants' characteristics. We conclude that the conflicting results are due to primarily different definitions of the dependent and independent constructs and their indicator variables, different research methods employed, and participant's demographic characteristics. In order to build e-learning theories and a cumulative research tradition, it is necessary to (1) define the dependent/independent constructs and their indicators, (2) employ common research methodology, and (3) test commonly accepted causal models. Further, we suggest the following three recommendation to guide the future research. They include using only dialogue, instead of mixing dialogue and interaction, conducting learning theory-based holistic approach, and proper treatment of contextual variables.
Software Project Planning Through Simulation of Entire Project's Problem-Space
Authors: Dayani Moshe , Gelbard Roy
Published: May 2017

The current research has two main objectives: 1) Integration of the system analyst's products together with the project manager's work, via handshaking of software tools used for these tasks (Software modeling tools, Project management tools, as well as Word and Excel files). 2) Simulation of the entire project's problem space subject to organization's policy and constraints in order to achieve best project planning in the given situation. For this purpose, a rule-based system, developed in this study, utilizes a simulation of entire project's problem-space, which is a Cartesian product composed of all system elements (as defined in the software modeling tool), and organization's policy, preferences and constraints, via a specific user interface (see Figure 1). Then the project manager can choose, by simple filtering, the appropriate planning, and the Gantt-chart and all plans' details are automatically exported to the Project Management tool.
ERP Implementation Projects in Asian Countries
Authors: Dezdar Shahin
Published: May 2017

This research studies critical success factors that influence the ERP implementation project in a Middle-Eastern country, namely Iran and compares the results with findings in a country in East Asia, namely China. A survey questionnaire was distributed to Iranian organizations with ERP systems. A total of 384 responses were collected and analysed using the Structural Equation Modelling. Findings are then compared, with the enterprises of China, to check for the similarities & differences. The outcomes showed that ERP implementation success in Iran is influenced by Top Management Support, Project Management Program, Organizational Culture, User Education & Training, ERP User Involvement, ERP User Characteristics, ERP Software Suitability, ERP Information Quality, ERP System Quality, ERP Vendor Quality. The central aim of the current research is to understand the most significant factors of ERP project success that help adopting companies to realize the benefits of ERP implementation.
IoT Setup for Co-measurement of Water Level and Temperature
Authors: Das Gupta Sujaya , Zambare M.S. , Shaligram A.D.
Published: May 2017

Recent time has witnessed severe scarcity of water owing to deficient rainfall in India. The current climatic conditions in the country, project the rise in temperature and arid conditions contributing substantially towards the evaporation losses. In order to deal with the looming crisis, it is peremptory to minimize evaporation losses in the water bodies, at least measure them to get a fair idea and initiate corrective measures. This paper aims to develop a system for continuous monitoring of the water level as an indicator to the evaporation process. The system also indicates temperature of the water which influences the evaporation rate.
Big Data Summarization Using Novel Clustering Algorithm and Semantic Feature Approach
Authors: Kolte Shilpa G. , Bakal Jagdish W.
Published: May 2017

This paper proposes a big data (i.e., documents, texts) summarization method using proposed clustering and semantic features. This paper proposes a novel clustering algorithm which is used for big data summarization. The proposed system works in four phases and provides a modular implementation of multiple documents summarization. The experimental results using Iris dataset show that the proposed clustering algorithm performs better than K-means and K-medodis algorithm. The performance of big data (i.e., documents, texts) summarization is evaluated using Australian legal cases from the Federal Court of Australia (FCA) database. The experimental results demonstrate that the proposed method can summarize big data document superior as compared with existing systems.
The Role of Shed PrPc in the Neuropathogenesis of HIV Infection
Authors: Megra Bezawit W. , Eugenin Eliseo A. , Berman Joan W.
Published: May 2017

HIV-1 enters the CNS soon after peripheral infection and causes chronic neuroinflammation and neuronal damage that leads to cognitive impairment in 40–70% of HIV-infected people. The nonpathogenic cellular isoform of the human prion protein (PrPc) is an adhesion molecule constitutively expressed in the CNS. Previously, our laboratory showed that shed PrPc (sPrPc) is increased in the cerebrospinal fluid of HIV-infected people with cognitive deficits as compared with infected people with no impairment. In this article, we demonstrate that CCL2 and TNF-α, inflammatory mediators that are elevated in the CNS of HIV-infected people, increase shedding of PrPc from human astrocytes by increasing the active form of the metalloprotease ADAM10. We show that the consequence of this shedding can be the production of inflammatory mediators, because treatment of astrocytes with rPrPc increased secretion of CCL2, CXCL-12, and IL-8. Supernatants from rPrPc-treated astrocytes containing factors produced in response to this treatment, but not rPrPc by itself, cause increased chemotaxis of both uninfected and HIV-infected human monocytes, suggesting a role for sPrPc in monocyte recruitment into the brain. Furthermore, we examined whether PrPc participates in glutamate uptake and found that rPrPc decreased uptake of this metabolite in astrocytes, which could lead to neurotoxicity and neuronal loss. Collectively, our data characterize mediators involved in PrPc shedding and the effect of this sPrPc on monocyte chemotaxis and glutamate uptake from astrocytes. We propose that shedding of PrPc could be a potential target for therapeutics to limit the cognitive impairment characteristic of neuroAIDS.
T Follicular Helper Cell–Derived IL-4 Is Required for IgE Production during Intestinal Helminth Infection
Authors: Meli Alexandre P. , Fontés Ghislaine , Leung Soo Cindy , King Irah L.
Published: May 2017

IgE production plays a crucial role in protective as well as pathogenic type 2 immune responses. Although the cytokine IL-4 is required for the development of IgE-producing plasma cells, the source of IL-4 and cellular requirements for optimal IgE responses remain unclear. Recent evidence suggests that T follicular helper (Tfh) cells are the primary producer of IL-4 in the reactive lymph node during type 2 immune responses. As Tfh cells are also required for the development of plasmablasts derived from germinal center and extrafollicular sources, we hypothesized that this cell subset is essential for the IgE plasmablast response. In this study, we show that during intestinal helminth infection, IL-4 derived from Tfh cells is required for IgE class switching and plasmablast formation. Notably, early IgE class switching did not require germinal center formation. Additionally, Tfh cell–derived IL-4 was required to maintain the Th2 response in the mesenteric lymph nodes of infected mice. Collectively, our results indicate that IL-4–producing Tfh cells are central orchestrators of the type 2 immune response in the reactive lymph nodes during parasitic helminth infection.
Comparing two statistical ensembles of quadrangulations: a continued fraction approach
Authors: Fusy Éric , Guitter Emmanuel
Published: May 2017

We use a continued fraction approach to compare two statistical ensembles of quadrangulations with a boundary, both controlled by two parameters. In the first ensemble, the quadrangulations are bicolored and the parameters control their numbers of vertices of both colors. In the second ensemble, the parameters control instead the number of vertices which are local maxima for the distance to a given vertex, and the number of those which are not. Both ensembles may be described either by their (bivariate)
generating functions at fixed boundary length
or, after some standard slice decomposition, by their (bivariate)
slice generating functions
. We first show that the fixed boundary length generating functions are in fact equal for the two ensembles. We then show that the slice generating functions, although different for the two ensembles, simply correspond to two different ways of encoding the same quantity as a continued fraction. This property is used to obtain explicit expressions for the slice generating functions in a constructive way.
The distance-dependent two-point function of quadrangulations: a new derivation by direct recursion
Authors: Guitter Emmanuel
Published: May 2017

We give a new derivation of the distance-dependent two-point function of planar quadrangulations by solving a new direct recursion relation for the associated slice generating functions. Our approach for both the derivation and the solution of this new recursion is in all points similar to that used recently by the author in the context of planar triangulations.
Finite horizon model predictive control of electrowetting on dielectric with pinning
Authors: Antil Harbir , Hintermüller Michael , Nochetto Ricardo H. , Surowiec Thomas M. , Wegner Donat
Published: May 2017

A time-discrete spatially-continuous electrowetting on dielectric (EWOD) model with contact line pinning is considered as the state system in an optimal control framework. The pinning model is based on a complementarity condition. In addition to the physical variables describing velocity, pressure, and voltage, the solid-liquid-air interface, i.e., the contact line, arises as a geometric variable that evolves in time. Due to the complementarity condition, the resulting optimal control of a free boundary problem is thus a mathematical program with equilibrium constraints (MPEC) in function space. In order to cope with the geometric variable, a finite horizon model predictive control approach is proposed. Dual stationarity conditions are derived by applying a regularization procedure, exploiting techniques from PDE-constrained optimization, and then passing to the limit in the regularization parameters. Moreover, a function-space-based numerical procedure is developed by following the theoretical limit argument used in the derivation of the dual stationarity conditions. The performance of the algorithm is demonstrated by several examples; including barycenter matching and trajectory tracking.
Aerosol emission factors from traditional biomass cookstoves in India:
Insights from field measurements
Authors: Pandey Apoorva , Patel Sameer , Pervez Shamsh , Tiwari Suresh , Yadama Gautam , Chow Judith C. , Watson John G. , Biswas Pratim , Chakrabarty Rajan K.
Published: May 2017

Abstract. Residential solid biomass cookstoves are important sources of aerosol emissions in India. Cookstove emission rates are largely based on laboratory experiments conducted using the standard water-boiling test, but real-world emissions are often higher owing to different stove designs, fuels, and cooking methods. Constraining mass emission factors (EFs) for prevalent cookstoves is important because they serve as inputs to bottom-up emission inventories used to evaluate health and climate impacts. Real-world EFs were measured during winter, 2015, for a traditional cookstove (chulha) burning fuel-wood (FW), agricultural residue (AG) and dung (DG) from different regions of India. Average (±95 % confidence interval) EFs for FW, AG, and DG were: 1) PM2.5 mass: 6.8 (4.7–9.4) g kg−1, 7.1 (3.9–11.8) g kg−1, and 14.5 (7.5–25.3) g kg−1, respectively; 2) elemental carbon (EC): 0.6 (0.4–0.9) g kg−1, 1.0 (0.4–2.0) g kg−1, and 0.6 (0.3–1.3) g kg−1, respectively; and 3) Organic carbon (OC): 3.1 (2.0–4.6) g kg−1, 4.5 (2.3–8.0) g kg−1, and 8.2 (4.2–15.01) g kg−1, respectively. The mean (±95 % confidence interval) OC-to-EC mass ratios were 6.5 (4.5–9.1), 7.6 (4.4–12.2), and 12.7 (8.8–17.8), respectively, with OC and EC quantified by the IMPROVE_A thermal/optical reflectance protocol. These real-world EFs are higher than those from laboratory-based measurements. Combustion conditions have larger effects on EFs than the fuel-types. We also report the carbon mass fractions of our aerosol samples determined using the thermal-optical reflectance method. The mass fraction profiles are consistent between the three fuel categories, but markedly different from those reported in past literature.
Influence of environmental humidity on measurements of benzene in ambient air by transportable GC-PID
Authors: Romero-Trigueros Cristina , Doval Miñarro Marta , González Ferradás Enrique
Published: May 2017

Abstract. Calibration of in situ analysers of air pollutants is usually done with dry standards. In this paper, the influence of environmental humidity on benzene measurements by gas chromatography coupled with a photo ionisation detector (GC-PID) is studied. Two identical chromatographs were calibrated for benzene with dry gases and subjected to measure reference standards with humidity (20 % and 80 % at 20 ºC). When measuring a concentration of 0.5 µg/m3 benzene in air, the levels of humidity tested did not produce any significant interference in measurements taken with any of the analysers. However, when measuring a concentration of 40 µg/m3, biases in measurements of 18 % and 21 % for each analyser, respectively, were obtained when the relative humidity of the sample was 80 % at 20 ºC. Further tests were carried out to study the nature of this interference. Results show that humidity interference depends on both the amount fractions of water vapour and benzene. If benzene concentrations in an area are close to its annual limit value (5 µg/m3), biases of 2.2 % can be expected when the absolute humidity is 8.6 g/cm3 –corresponding to a relative humidity of 50 % at 20 ºC-. This can be accounted for in the uncertainty budget of measurements with no need for corrections. If benzene concentrations are above the annual limit value, biases become higher. Thus, in these cases, actions should be taken to reduce the humidity interference, as an underestimation of benzene concentrations may cause a mismanagement of air quality in these situations.
Anatomical structure overrides temperature controls on magnesium uptake -- calcification in the Arctic/subarctic coralline algae Leptophytum laeve and Kvaleya epilaeve (Rhodophyta; Corallinales)
Authors: Nash Merinda C. , Adey Walter
Published: May 2017

Abstract. Calcified coralline red algae are ecologically key organisms in photic benthic environments. In recent decades they have become important climate proxies, especially in the Arctic and Subarctic. It has been widely accepted that Magnesium content in coralline tissues is directly a function of ambient temperature, and this is a primary basis for their value as a climate archive. In this paper we show for two genera of Arctic/Subarctic corallines, Leptophytum laeve and Kvaleya epilaeve, that previously unrecognized complex tissue and cell wall anatomy bears a variety of basal signatures for Mg content, with the accepted temperature relationship being secondary. The interfilament carbonate has lower Mg than adjacent cell walls and the hypothallial cell walls have the highest Mg content. The internal structure of the hypothallial cell walls can differ substantially from the perithallial radial cell wall structure. Using high-magnification Scanning Electron Microscopy and etching we expose the nm-scale structures within the cell walls and interfilament. Fibrils concentrate at the internal and external edges of the cell walls. Fibrils ~ 10 nm thick appear to thread through the radial Mg-calcite grains and form concentric bands within the cell wall. This banding may control Mg distribution within the cell. Similar fibril banding is present in the hypothallial cell walls but not the interfilament. Climate archiving with corallines can achieve greater precision with recognition of these parameters. This paper is part of a series of investigations on controls on Mg uptake and distribution within the crusts of a range of coralline genera.
Sedimentary record from the Canada Basin, Arctic Ocean: implications for late to middle Pleistocene glacial history
Authors: Dong Linsen , Liu Yanguang , Shi Xuefa , Polyak Leonid , Huang Yuanhui , Fang Xisheng , Liu Jianxing , Zou Jianjun , Wang Kunshan , Sun Fuqiang , Wang Xuchen
Published: May 2017

Abstract. Sediment core ARC4-BN05 collected from the Canada Basin, Arctic Ocean, covers the late to middle Quaternary (Marine Isotope Stage – MIS – 1–15, ca. 0.5–0.6 Ma) as estimated by correlation to earlier proposed Arctic Ocean stratigraphies and AMS14C dating of the youngest sediments. Detailed examination of clay and bulk mineralogy along with grain size, content of Ca and Mn, and planktic foraminiferal numbers in core ARC4–BN05 provides important new information about sedimentary environments and provenance. We use increased contents of coarse debris as an indicator of glacier collapse events at the margins of the western Arctic Ocean, and identify the provenance of these events from mineralogical composition. Notably, peaks of dolomite debris, including large dropstones, track the Laurentide Ice Sheet (LIS) discharge events to the Arctic Ocean. Major LIS inputs occurred during the stratigraphic intervals estimated as MIS 3, intra-MIS 5 and 7 events, MIS 8, and MIS 10. Inputs from the East Siberian Ice Sheet (ESIS) are inferred from peaks of smectite, kaolinite, and chlorite associated with coarse sediment. Major ESIS sedimentary events occurred in the intervals estimated as MIS 4, MIS 6 and MIS 12. Differences in LIS vs. ESIS inputs can be explained by ice-sheet configurations at different sea levels, sediment delivery mechanisms (iceberg rafting, suspension plumes, and debris flows), and surface circulation. A long-term change in the pattern of sediment inputs, with an apparent step change near the estimated MIS 7–8 boundary (ca. 0.25 Ma), presumably indicates an overall glacial expansion at the western Arctic margins, especially in North America.
Single-block rockfall dynamics inferred from seismic signal analysis
Authors: Hibert Clément , Malet Jean-Philippe , Bourrier Franck , Provost Floriane , Berger Frédéric , Bornemann Pierrick , Tardif Pascal , Mermin Eric
Published: May 2017

Abstract. Seismic monitoring of mass movements can significantly help to mitigate the associated hazards; however, the link between event dynamics and the seismic signals generated is not completely understood. To better understand these relationships, we conducted controlled releases of single blocks within a soft-rock (black marls) gully of the Rioux-Bourdoux torrent (French Alps). A total of 28 blocks, with masses ranging from 76 to 472 kg, were used for the experiment. An instrumentation combining video cameras and seismometers was deployed along the travelled path. The video cameras allow reconstructing the trajectories of the blocks and estimating their velocities at the time of the different impacts with the slope. These data are compared to the recorded seismic signals. As the distance between the falling block and the seismic sensors at the time of each impact is known, we were able to determine the associated seismic signal amplitude corrected for propagation and attenuation effects. We compared the velocity, the potential energy lost, the kinetic energy and the momentum of the block at each impact to the true amplitude and the radiated seismic energy. Our results suggest that the amplitude of the seismic signal is correlated to the momentum of the block at the impact. We also found relationships between the potential energy lost, the kinetic energy and the seismic energy radiated by the impacts. Thanks to these relationships, we were able to retrieve the mass and the velocity before impact of each block directly from the seismic signal. Despite high uncertainties, the values found are close to the true values of the masses and the velocities of the blocks. These relationships allow for gaining a better understanding of the physical processes that control the source of high-frequency seismic signals generated by rockfalls.
Assessment of extreme flood events in a changing climate for a long-term planning of socio-economic infrastructure in the Russian Arctic
Authors: Shevnina Elena , Kourzeneva Ekaterina , Kovalenko Viktor , Vihma Timo
Published: May 2017

Abstract. Climate warming has been more acute in the Arctic than at lower latitudes and this tendency is expected to continue. This generates major challenges for economic activity in the region. Among other issues is the long-term planning and development of socio-economic infrastructure (dams, bridges, roads, etc.), which require climate-based forecasts of the frequency and magnitude of detrimental flood events. To estimate the cost of the infrastructure and operational risk, a probabilistic form of long-term forecasting is preferable. In this study, a probabilistic model to simulate the parameters of the probability density function (PDF) for multi-year runoff based on a projected climatology is applied to evaluate changes in extreme floods for the territory of the Russian Arctic. The model is validated by cross-comparison of the modelled and empirical PDFs using observations from 23 sites located in northern Russia. The mean values and coefficients of variation (CVs) of the spring flood depth of runoff are evaluated under four climate scenarios, using simulations of six climate models for the period 2010–2039. Regions with substantial expected changes in the means and CVs of spring flood depth of runoff are outlined. For the sites located within such regions, it is suggested to account for the future climate change in calculating the maximal discharges of rare occurrence. An example of engineering calculations for maximal discharges with 1 % exceedance probability is provided for the Nadym River at Nadym.
Simultaneous in situ characterisation of bubble dynamics and a spatially resolved concentration profile: a combined Mach–Zehnder holography and confocal Raman-spectroscopy sensor system
Authors: Guhathakurta Jajnabalkya , Schurr Daniela , Rinke Günter , Dittmeyer Roland , Simon Sven
Published: May 2017

Abstract. For a reaction between a gaseous phase and a liquid phase, the interaction between the hydrodynamic conditions, mass transport and reaction kinetics plays a crucial role with respect to the conversion and selectivity of the process. Within this work, a sensor system was developed to simultaneously characterise the bubble dynamics and the localised concentration measurement around the bubbles. The sensor system is a combination of a digital Mach–Zehnder holography subsystem to measure bubble dynamics and a confocal Raman-spectroscopy subsystem to measure localised concentration. The combined system was used to investigate the chemical absorption of CO2 bubbles in caustic soda in microchannels. The proposed set-up is explained and characterised in detail and the experimental results are presented, illustrating the capability of the sensor system to simultaneously measure the localised concentration of the carbonate ion with a good limit of detection and the 3-D position of the bubble with respect to the spot where the concentration was measured.
Design and analysis of a 3-DOF planar micromanipulation stage with large rotational displacement for micromanipulation system
Authors: Ding Bingxiao , Li Yangmin , Xiao Xiao , Tang Yirui , Li Bin
Published: May 2017

Abstract. Flexure-based mechanisms have been widely used for scanning tunneling microscopy, nanoimprint lithography, fast servo tool system and micro/nano manipulation. In this paper, a novel planar micromanipulation stage with large rotational displacement is proposed. The designed monolithic manipulator has three degrees of freedom (DOF), i.e. two translations along the X and Y axes and one rotation around Z axis. In order to get a large workspace, the lever mechanism is adopted to magnify the stroke of the piezoelectric actuators and also the leaf beam flexure is utilized due to its large rotational scope. Different from conventional pre-tightening mechanism, a modified pre-tightening mechanism, which is less harmful to the stacked actuators, is proposed in this paper. Taking the circular flexure hinges and leaf beam flexures hinges as revolute joints, the forward kinematics and inverse kinematics models of this stage are derived. The workspace of the micromanipulator is finally obtained, which is based on the derived kinematic models.
Forecast skill score assessment of a relocatable ocean prediction system, using a simplified objective analysis method
Authors: Onken Reiner
Published: May 2017

Abstract. A Relocatable Ocean Prediction System (ROPS) was employed to an observational data set which was collected in June 2014 in the waters to the west of Sardinia (Western Mediterranean) in the mainframe of the REP14-MED experiment. The observational data, comprising almost 5000 temperature and salinity profiles from a fleet of underwater gliders and shipborne probes, were assimilated in the Regional Ocean Modeling System (ROMS) which is the heart of ROPS, and verified against independent observations from ScanFish tows by means of the forecast skill score as defined by Murphy (1993). A simplified objective analysis (OA) method was utilised for assimilation, taking account of only those profiles which were located within a predetermined time window W. As a result of a sensitivity study, the highest skill score was obtained for a correlation length scale C = 12.5 km, W = 24 hours, and r = 1, where r is the ratio between the error of the observations and the background error, both for temperature and salinity. Additional ROPS runs showed that (i) the skill score of assimilation runs was mostly higher than the score of a control run without assimilation, (i) the skill score increased with increasing forecast range, and (iii) the skill score for temperature was higher than the score for salinity in the majority of cases. Further on, it is demonstrated that the vast number of observations can be managed by the applied OA method without data reduction, enabling timely operational forecasts even on a commercially available Personal Computer or a laptop.
Stable accumulation patterns around Dome C, East Antarctica, over the last glacial cycle
Authors: Cavitte Marie G.~P. , Parrenin Frédéric , Ritz Catherine , Young Duncan A. , Blankenship Donald D. , Frezzotti Massimo , Roberts Jason L.
Published: May 2017

Abstract. We reconstruct the pattern of surface accumulation in the region around Dome C, East Antarctica, through the last glacial cycle. We use a set of internal isochrones interpreted from various ice-penetrating radar surveys and a 1D pseudo-steady ice flow model to invert for both time-averaged accumulation rates and paleoaccumulation rates between isochrone pairs. We observe that the surface accumulation pattern is stable through the last 128 kyrs, both the large-scale (100s km) gradients which reflect current modeled and observed precipitation gradients in the region, as well as the small-scale (10s km) accumulation variations linked to snow redistribution at the surface due to changes in its slope and curvature in the prevailing wind direction. This suggests a stable position of the dome throughout the last glacial cycle.
The Resource Curse Hypothesis in Lao Economy
Authors: Khinsamone Soukvisan
Published: May 2017

The purpose of this paper is to investigate the adaptability of the resource curse hypothesis for Lao economy. The study verifies the two crowding-out logics that resource abundance would crowd out manufacturing activities and/or savings and investment, by examining their causalities and impulse responses in a vector auto-regression (VAR) model estimation. The estimation outcomes implied the existence of the resource curse in Lao economy: resource production has crowded out manufacturing activities through real exchange rate appreciation, thereby causing the Dutch Disease; and resource production has not contributed significantly to capital accumulation, thereby being not consistent with Hartwick-rule. The study contributed to the literature by verifying two kinds of crowding-out logics on the resource curse by applying a VAR model: the crowding-out of manufacturing activities as a sectoral allocation, and the crowding-out of savings and investment as an intertemporal allocation. The study might also be valuable to the policy makers, since it proposed a strategy for transforming Lao economic structure from “resource curse” to “resource blessing” by setting up some institutional framework to allocate resource revenues to infrastructure development.
Kinship and intimacy
Authors: LaFollette Hugh
Published: May 2017

We think about personal relationships in two distinct ways. The first focuses on relationships between blood relatives: parents and their children, siblings, and perhaps first cousins. The second focuses on intimacy: relationships where each individual is honest to and trusting of the other; each cares for the other and seeks the other’s company. In this article I ask how these two conceptions are, can be, or should be linked. Should we strive to make all relationships with kin intimate?  Even if the answer is a qualified “No,” does that mean relationships with kin are not valuable?  I offer some tentative answers to these questions. Despite its limitations, I hope this provides a framework from which future exploration of these issues might profitably begin.