bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of surface corrugation and tip oscillation in single-molecule manipulation with a non-contact atomic force microscope
Authors: Wagner Christian , Fournier Norman , Tautz F Stefan , Temirov Ruslan
Published: February 2014

Scanning probe microscopy (SPM) plays an important role in the investigation of molecular adsorption. The possibility to probe the molecule–surface interaction while tuning its strength through SPM tip-induced single-molecule manipulation has particularly promising potential to yield new insights. We recently reported experiments, in which 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) molecules were lifted with a qPlus-sensor and analyzed these experiments by using force-field simulations. Irrespective of the good agreement between the experiment and those simulations, systematic inconsistencies remained that we attribute to effects omitted from the initial model. Here we develop a more realistic simulation of single-molecule manipulation by non-contact AFM that includes the atomic surface corrugation, the tip elasticity, and the tip oscillation amplitude. In short, we simulate a full tip oscillation cycle at each step of the manipulation process and calculate the frequency shift by solving the equation of motion of the tip. The new model correctly reproduces previously unexplained key features of the experiment, and facilitates a better understanding of the mechanics of single-molecular junctions. Our simulations reveal that the surface corrugation adds a positive frequency shift to the measurement that generates an apparent repulsive force. Furthermore, we demonstrate that the scatter observed in the experimental data points is related to the sliding of the molecule across the surface.
A BIOMECHANICAL COMPARISON OF BLOOD FLOW AND MECHANICAL CHARACTERISTICS OF THE EARLY ARTERIOSCLEROTIC AND HEALTHY ARTERIES USING A FLUID-WALL INTERACTION MODEL
Authors: He Fan
Published: February 2014

A fluid-wall interaction model was introduced to investigate and compare the properties of blood flow, wall stress and deformation of the early arteriosclerotic and healthy arteries. The unsteady blood flow was assumed to be laminar, Newtonian, viscous and incompressible. The vessel wall was assumed to be linear-elastic, isotropic and incompressible. The fluid-wall interaction algorithm was constructed using a finite element method. The results show that the blood flow, wall stress and strain distributions of both arteries are similar. The blood flow characteristics of the diseased artery are similar to those of the healthy artery, which may be the main reason that the early arteriosclerosis could be reversible and treated by itself. The values of velocities, wall shear stresses, pressures and wall stresses of the diseased artery are approximately equal to those of the healthy artery, however the values of wall strains of both arteries are different and the cyclic strain ratio of the diseased artery is higher than that of the healthy artery. A high cyclic strain ratio is thought to be disadvantageous for arterial tissue. A new parameter anti-fatigue index (AFI) is introduced to evaluate mechanical fatigue of artery in the study. AFI is effective in characterizing the anti-fatigue ability of artery.
ASSESSING ABNORMAL GAITS OF PARKINSON'S DISEASE PATIENTS USING A WEARABLE MOTION DETECTOR
Authors: Su Rung-Hung , Hsu Yeh-Liang , Chan Lung , Lin Hanjun , Yang Che-Chang
Published: February 2014

Accelerometers have been widely used in wearable systems for gait analysis. Several gait cycle parameters are provided to quantify the level of gait regularity and symmetry. This study attempts to assess abnormal gaits of Parkinson disease (PD) patients based on the gait cycle parameters derived in real-time from an accelerometry-based wearable motion detector (WMD). The results of an experiment with 25 healthy young adults showed that there were significant differences between gait cycle parameters of normal gaits and abnormal gaits derived from the WMD. Five PD patients diagnosed as Hoehn and Yahr stage I to II were recruited. It is difficult to collect data of abnormal gaits of the PD patients; therefore, ranges of the gait cycle parameters of abnormal gaits of PD patients were estimated statistically based on the "lower confidence limit" of the gait cycle parameters of their normal gaits. These results may lead to the future development of wearable sensors enabling real-time recognition of abnormal gaits of PD patients. Ambulatory rehabilitation, gait assessment and personal telecare for people with gait disorders are also possible applications.
Nanosciences and Nanotechnologies
Authors: Finardi Ugo
Published: February 2014

Nanotechnologies and nanosciences are one of the most important novelties in the panorama of sciences and technologies. This work presents: their evolution since their first emergence; their most important scientific and technological features; the analysis of their role in society and economics in the socio-economic literature; their main areas of scientific and technological evolution and deployment; the motivations of the interests towards them in science and society. Nanotechnologies and nanosciences originate from a recombination of pre-existing research fields; they have the character of being a general-purpose technology and are linked to classic scientific areas. The character of Disruptive Technology of nanotechnologies and nanosciences is assessed also with the use of experimental data from a bibliographic analysis. Several examples of nanotechnological items are presented, either yet in the hands of consumers or showing promising features for the near future. The accurate description of this newly expanding area of sciences and technologies can provide important insights to the scholars and practitioners who are engaged in the study of this field of science, technology, and innovation, or aim at comparing this with related fields.
A Networking Paradigm Inspired by Cell Communication Mechanisms
Authors: Nakano Tadashi
Published: February 2014

This chapter provides a brief review of molecular communication, a networking paradigm inspired by cell communication mechanisms. In molecular communication, information is encoded to and decoded from molecules, rather than electrons or electromagnetic waves. Molecular communication provides bio-compatible and energy-efficient solutions with massive parallelization at the nano-to-micro scale; it is expected to play a key role in a multitude of domains including health, the environment, and ICT (Information Communication Technology). Models and methods of molecular communication are also reviewed, and research challenges that need to be addressed for further advancement of the molecular communication paradigm are discussed.
Bionanotechnology
Authors: Reisner David E. , Brauer Samuel , Zheng Wenwei , Vulpe Chris , Bawa Raj , Alvelo Jose , Gericke Mariekie
Published: February 2014

Bionanotechnology is multidisciplinary knowledge gained at the intersection of biology and nanotechnology. Certainly, biology operates in the nanoscale regime, using natural processes that occur in the nanoscale, by convention, under 100 nm in dimension. Therefore, bionanotechnology relates to those subtopics in the biological life sciences that exploit the analytical and experimental tools of nanotechnology. This chapter makes no pretense of acting as a comprehensive treatise, but rather selects a mix of timely topics that span over a wide set of tools and applications. It is addressed to practitioners, researchers, faculty, and university/college students within the field of bioengineering/biomedical engineering; it is also addressed to other closely-related governmental, non-governmental, and industrial entities.
Electrostatic Potential at Nuclei
Authors: Ilieva Sonia , Galabov Boris
Published: February 2014

The chapter surveys mostly original work of the authors on the application of the electrostatic potential at nuclei (EPN) as a reactivity index in quantifying hydrogen bonding as well as different reactions of organic compounds. The EPN index was defined and introduced by E. B. Wilson (1962). However, it was first applied as a reactivity index much later in works from our laboratory (Bobadova-Parvanova & Galabov, 1998; Galabov & Bobadova-Parvanova, 1999; Dimitrova, Ilieva, & Galabov, 2002; Cheshmedzhieva, Ilieva, Hadjieva, Trayanova, & Galabov, 2009; Galabov, Cheshmedzhieva, Ilieva, & Hadjieva, 2004; Galabov, Ileiva, & Schaefer, 2006; Galabov, Nikolova, Wilke, Schaefer, & Allen, 2008; Galabov, Ilieva, Hadjieva, Atanasov, & Schaefer, 2008; Koleva, Galabov, Wu, Schaefer, & Schleyer, 2009). Numerous applications showed that the EPN index, an accurate quantum mechanical quantity, predicts with remarkable accuracy the energy shifts accompanying hydrogen bonding. The theoretically evaluated EPN descriptor correlates also excellently with experimental and theoretically evaluated kinetic parameters for a number of important organic reactions. Based on these findings an efficient computational approach for the evaluation of substituent constants was developed.
Nanoparticle Scattering, Absorption, and Interface Effects for Surface Plasmon Enhanced Thin Silicon Solar Cells
Authors: Kadakia Nirag
Published: February 2014

Recently, surface plasmons have been employed in a variety of methods to increase the efficiency of solar cells. Surface plasmons are oscillations of electrons that arise from surface effects of light interaction with materials that have appreciable free carrier densities; their resonance is confined to a region that depends on the dielectric response of the medium. It has been observed that noble metals exhibit this resonance within visible- near IR range, making them an attractive candidate for silicon solar cells whose primary absorption bands are in this region. Research in silicon-based plasmonic solar cells has utilized the high scattering cross section and favorable angular distributions of noble metal nanoparticle-scattered radiation to increase absorption of thin silicon devices, which are normally weakly absorbing for photons of energy below 2 eV. The interaction is subject to interface effects, interferences of scattered and incident radiation, and the dielectric nature of the embedding medium or surface. In addition, perturbations caused by the longitudinal field of the metal nanoparticle may theoretically enhance the direct interband transitions of free carriers near the particle surface, further enhancing the photocurrent. This latter possibility has yet to be fully explored experimentally in crystalline silicon photovoltaics.
Nanotechnology and Polymer Solar Cells
Authors: Buxton Gavin
Published: February 2014

In response to environmental concerns there is a drive towards developing renewable, and cleaner, energy technologies. Solar cells, which harvest energy directly from sunlight, may satisfy future energy requirements, but photovoltaic devices are currently too expensive to compete with existing fossil fuel based technologies. Polymer solar cells, on the other hand, are cheaper to produce than conventional inorganic solar cells and can be processed at relatively low temperatures. Furthermore, polymer solar cells can be fabricated on surfaces of arbitrary shape and flexibility, paving the way to a range of novel applications. Therefore, polymer solar cells are likely to play an important role in addressing, at least in some small part, man’s future energy needs. Here, the physics of polymer photovoltaics are reviewed, with particular emphasis on the computational tools which can be used to investigate these systems. In particular, the authors discuss the application of nanotechnology in self-assembling complex nanoscale structures which can be tailored to optimize photovoltaic performance. The role of computer simulations, in correlating these intricate structures with their performance, can not only reveal interesting new insights into current devices, but also elucidate potentially new systems with more optimized nanostructures.
C/C-ZrB2-ZrC-SiC Composites Derived from Polymeric Precursor Infiltration and Pyrolysis Part I
Authors: Zhang Weigang , Xie Changming , Ge Min , Wei Xi
Published: February 2014

Two-dimensional C/C-ZrB2-ZrC-SiC composites with three phases of ultra high temperature ceramics (UHTCs) are fabricated for the first time using blending pre-ceramic polymeric precursors through the traditional polymer infiltration and pyrolysis (PIP) technique, in which a porous carbon fiber reinforced pyrolytic carbon (C/C) with a porosity of about 60% is prepared as preforms. The fabricated composite possesses a matrix of 20ZrB2-30ZrC-50SiC, which is obtained by co-pyrolysis of three pre-ceramic polymers solution in xylene with certain molar ratios. Pyrolysis of these ZrB2-ZrC-SiC pre-ceramic precursors is studied with XRD characterization of the residual solids. The gas phase products are analysized with an on-line GC-MS-FTIR coupling technique, which confirms the formation of crystalline ZrC and ZrB2 from these precursors at temperatures above 1400°C. Possible mechanisms of pyrolysis and formation of pure ZrB2 from the precursors with various B/Zr molar ratios are suggested. The densification process and microstructures of the fabricated composite are studied. It is found that a composite with a bulk density of 2.06 g/cm3 and open porosity of 9.6% can be obtained after 16 PIP cycles. The formed matrix exhibits homogeneous dispersion of three matrix ceramics without any oxide impurities, i.e., the nano sized ZrB2 and ZrC particles dispersed in a continuous SiC ceramic with clean crystalline boundaries and particle dimensions less than 200 nm. No erosion or interface reaction occurs upon the carbon fiber reinforcement, which therefore avoids a dramatic deterioration of mechanical strength of carbon fiber and the composite. Improvement of PIP benefits from two aspects; firstly, the dense pyrolytic carbon interphase deposited on fiber surface by CVI serves as barrier coating and secondly, pyrolysis of the novel organic polymeric precursors does not release corrosive by-products such as hydrogen chloride.
System-Level Design of NoC-Based Dependable Embedded Systems
Authors: Tagel Mihkel , Ellervee Peeter , Jervan Gert
Published: February 2014

Technology scaling into subnanometer range will have impact on the manufacturing yield and quality. At the same time, complexity and communication requirements of systems-on-chip (SoC) are increasing, thus making a SoC designer goal to design a fault-free system a very difficult task. Network-on-chip (NoC) has been proposed as one of the alternatives to solve some of the on-chip communication problems and to address dependability at various levels of abstraction. This chapter concentrates on system-level design issues of NoC-based systems. It describes various methods proposed for NoC architecture analysis and optimization, and gives an overview of different system-level fault tolerance methods. Finally, the chapter presents a system-level design framework for performing design space exploration for dependable NoC-based systems.
Static Telecytological Applications for Proficiency Testing
Authors: Archondakis Stavros
Published: February 2014

In recent years, informatics and computer sciences have changed dramatically the practice of clinical cytopathology. New types of cameras and microscopes, connected to computers made possible image capture and transmission (telecytology). The wide implementation of telemedical systems in the field of cytopathology became a necessity dictated by the need of real-time results for therapeutic decisions. A telemedical application is a valuable tool for cytopathologists in order to manage and promote interlaboratory collaboration. The result is better cytological data management and sharing. ISO 15189:2007 for medical laboratories requires successful participation in proficiency testing programs. This chapter emphasizes on the necessity of developing a proficiency test for cytopathology labs wishing to be accredited according to ISO 15189:2007, and examines the feasibility of using low cost telemedical applications and solutions for this purpose. Furthermore, this chapter gives clear and comprehensive guidance concerning various financial, legal, professional, and ethical problems in this field.
Probing the Reactive Center for Site Selective Protonation in a Molecule by the Local Density Functional Descriptors
Authors: Rajak Sandip Kumar , Islam Nazmul , Ghosh Dulal C.
Published: February 2014

In this study, the authors have explored the efficacy of the local density functional descriptors like the fukui functions (f), the local softness (s) and the local philicity as probe for the reactive centers and site selectivity of the chemico-physical process of protonation of some molecules having multiple site for protonation, viz CH3NCO (Methyl isocyanate), CH3NCS (methyl isothiocyanate), NH2OH (hydroxyl amine), NH2OCH3 (o-methylhydroxylamine), CH3NHOH (N-methylhydroxylamine), NH2CH2COOH (glycine), CH3CH(NH2)COOH (alanine) and OHCH2CH2NH2 (ethanol amine). The authors have seen in terms of the numerical values of the local descriptors measures the reactivity (nucleophilicity) of a particular atomic site of a donor center towards a proton. In all cases, it can be said that the dynamic chemico-physical process of site selectivity can nicely be correlated in terms of the computed values of the local descriptors. Thus, it is found that the theoretical descriptors of the DFT can be efficiently exploited to study the mechanism of site selectivity in a chemical reaction.
Carbon Vacancy Ordered Non-Stoichiometric ZrC0.6
Authors: Hu Wentao , Tian Yongjun , Liu Zhongyuan
Published: February 2014

The starting nanopowders of non-stoichiometric zirconium carbide (ZrCx) were fabricated via milling Zr powders in toluene for different dwell times. The carbon content was determined to depend on the milling time and the used amount of toluene. The bulk non-stoichiometric ZrCx with different x were prepared by spark plasma sintering of the obtained ZrCx nanopowders. The microstructural features of a sintered ZrC0.6 sample were investigated via the measurements of XRD, TEM, and HRTEM. It was found that the carbon vacancies have an ordering arrangement in C sublattice, forming a Zr2C-type cubic superstructural phase with space group of . Moreover, it was observed that the superstructural phase exists in nano-domains with an average size of ~30 nm owing to the ordering length in nanoscale. During the heating treatment in air, it was recognized that the diffusion of oxygen atoms is significantly facilitated through the ordered carbon vacancies. For the heating treatment at low temperature (<300°C), the oxygen atoms diffuse easily into and occupy the ordered carbon vacancies, forming the oxy-carbide of ZrC0.6O0.4 with ordered oxygen atoms. At the heating temperature higher than 350°C an amorphous layer of ZrC0.6Oy>0.4 was identified to be formed due to the diffusion of superfluous oxygen atoms into Zr-tetrahedral centers. Inside the amorphous layer, the metastable tetragonal zirconia nanocrystals are recognized to be gradually developed.
Modeling of Quantum Key Distribution System for Secure Information Transfer
Authors: Rumyantsev K. E. , Golubchikov D. M.
Published: February 2014

This chapter is an analysis of commercial quantum key distribution systems. Upon analysis, the generalized structure of QKDS with phase coding of a photon state is presented. The structure includes modules that immediately participate in the task of distribution and processing of quantum states. Phases of key sequence productions are studied. Expressions that allow the estimation of physical characteristics of optoelectronic components, as well as information processing algorithms impact to rate of key sequence production, are formed. Information security infrastructure can be utilized, for instance, to formulate requirements to maximize tolerable error level in quantum channel with a given rate of key sequence production.
Designing Biomedical Stents for Vascular Therapy
Authors: Paul Arghya
Published: February 2014

The breakthrough technologies of stent have revolutionized the medical industry, particularly in the field of percutaneous coronary interventions and other vascular therapies. However, recent concerns of late stent thrombosis and in-stent restenosis have rekindled an interest in developing new and improved therapeutic stent devices. A multidisciplinary approach of regeneration therapy, biomedicine, and nanotechnology is the next frontier for this. The chapter presented here gives a comprehensive overview of the evolving stent technologies for efficient vascular tissue therapy and articulates the potential of these technologies to design the next generation of therapeutic stent. In addition, the chapter also encompasses upcoming technologies to develop bioactive stents for efficient healing and remodeling of damaged local vascular biology.
Preparation of a Uranium Conversion Plant’s Nuclear Waste for Final Disposal by Means of Magnetically Assisted Chemical Separation
Authors: Ghaemi Ahad , Maghsudi Mehdi , Hanifpour Fatemeh , Samadfam Mohammad
Published: February 2014

Uranium is separated from the raffinate of Isfahan’s uranium conversion solvent extraction process by means of solvent coated magnetic nanoparticles. These particles were synthesized via chemical co-precipitation and were analyzed by XRD, TEM and TGA methods. The particles’ surface were modified with D2EHPA and analyzed with FT-IR method. The results revealed that 0.5 M nitric acid and 25% w/w D2EHPA on nanoparticles gives the maximum uranium extraction yield. The raffinate of the solvent extraction plant can be disposed safely after its uranium content reduces to the allowable values.
Internal parasites and health management of pigs in Burayu District, Oromia Regional State, Ethiopia
Authors: Kumsa Bersissa , Kifle Elias
Published: February 2014

The study determined the prevalence and major types of gastrointestinal parasites in pigs and assessed the health management practices on farms in Burayu District in West Shoa Zone of Oromia Regional State, Ethiopia. The study was performed from November 2007 to April 2008 using standard coprological examination and a well-organised questionnaire survey. Of the 272 pigs examined for the presence of gastrointestinal parasites, 36 (13.2%) were infected with one or more types of parasite. Neither age nor management system proved to be a statistically significant factor in the prevalence of parasites. The highest prevalence of parasites was recorded in December, January and April, whereas the lowest was observed in February. Significant variation in the prevalence of parasites was noticed amongst study months. The majority of farmers did not use acaricides to treat and control external parasites. Anthelmintics were not used by any of the farmers. Some 76.1% of the farmers never used any type of treatment for sick pigs; 21.7% of the farmers used modern treatment and 2.2% of the farmers used traditional medicines. More than 95.0% of pigs were kept on soil floors and only 10.9% of the housing systems had good ventilation. Dung was removed at least every three days, with the majority of farmers (91.2%) removing it every morning. This study provided evidence for the occurrence of internal parasites in pigs kept in Burayu District in Oromia. Further epidemiological studies are needed to determine the zoonotic and economic importance of pig parasites in other parts of Ethiopia.
Stereotactic biopsy of brainstem lesions: Techniques, efficacy, safety, and disease variation between adults and children: A single institutional series and review
Authors: Manoj N. , Arivazhagan A. , Bhat D. I. , Arvinda H. R. , Mahadevan A. , Santosh V. , Devi B. Indira , Sampath S. , Chandramouli B. A.
Published: February 2014

Background: Stereotactic biopsy of brainstem lesions have been performed with varying indications, with most of the literature reporting on children. Materials and Methods: The present study retrospectively analyzed all cases that underwent stereotactic biopsy for brainstem lesion in both adult and pediatric population between 1994 and 2009 in a single tertiary neurosurgical center. The clinical and radiological features, technique of the procedure, morbidity, diagnostic accuracy, spectrum of diagnosis, and variations in adult and pediatric population were analyzed. Results: Eighty-two patients were included in the study. Computed tomography (CT) was used as guidance in 73 (38 children and 35 adults) patients and magnetic resonance imaging (MRI) in 9 (3 children and 6 adults). The biopsy was performed in a procedure room under local anesthesia in most adults, while children required sedation. Glioblastoma comprised 29.3% of all pathologies in children, compared with only 4.9% of the pathologies in adult population (P = 0.007). Tuberculosis was the next major diagnosis (9.8%). In 12 patients, initial biopsy was inconclusive. Following a repeat biopsy in 5 of these patients, a diagnosis was possible for 75/82 (91.5%) patients by STB. The location of the target, the choice of entry, the radiological characteristic of the lesion, enhancement pattern, and age group did not significantly correlate with the occurrence of inconclusive biopsy. Permanent complications occurred in two patients (2.4%). There was no mortality in this series. Conclusion: Stereotactic biopsy has an important role in brainstem lesions, more significantly in adults, due to wider pathological spectrum. It can be performed safely under local anesthesia through a twist drill craniostomy in most of the adults.
Chiari Type I malformation yielded to the diagnosis of Crouzon syndrome
Authors: Canpolat Aydin , Akçakaya Mehmet Osman , Altunrende Emre , Özlü Harun Mehmet , Duman Hakan , Ton Tuğrul , Akdemir Osman
Published: February 2014

Chiari malformation Type I (CM-I) related to syndromic craniosynostosis in pediatric patients has been well-studied. The surgical management consists of cranial vault remodeling with or without posterior fossa decompression. There were also cases, in whom CM-I was diagnosed prior to the craniosynostosis in early childhood. We present a 16-year-old boy who admitted with symptoms related to CM-I. With careful examination and further genetic investigations, a diagnosis of Crouzon syndrome was made, of which the patient and his family was unaware before. The patient underwent surgery for posterior fossa decompression and followed-up for Crouzon’s syndrome. To our knowledge, this is the only case report indicating a late adolescent diagnosis of Crouzon syndrome through clinical symptoms of an associated CM-I.
Safety and Efficacy of Sugammadex for Neuromuscular Blockade Reversal
Authors: Lobaz Steven , Clymer Mark , Sammut Mario
Published: February 2014

Since its first human use in 2005, the γ-cyclodextrin sugammadex (Org 25969) has had the potential to become the reversal agent of choice, for rocuronium- or vecuronium-induced neuromuscular blockade. Sugammadex binds to the aminosteroid neuromuscular blocker, encapsulating it and extracting it from the neuromuscular junction, effectively ceasing activity and allowing neuromuscular transmission to recover rapidly. Phases I–III and subsequent trials have found sugammadex to be safe and effective in a wide range of doses and for the reversal of a range of depth of muscle relaxation in healthy volunteers and a variety of disease states. Sugammadex use may allow refinement of anesthetic practice and improvement in surgical conditions, through the maintenance of deep neuromuscular blockade right to the end of surgery, with subsequent rapid reversal. Debate remains about the use of sugammadex in the treatment of rocuronium anaphylaxis and airway emergencies. The high price of sugammadex currently prohibits its routine use, but if the price falls, after expiry of its patent, it may become cost-effective as a readily available agent in certain specific clinical situations. Serious adverse reactions have occurred in less than 1% of patients and are most commonly because of hypersensitivity. No deaths have been reported, but caution is advised in neonates, pediatrics, and pregnancy where data are lacking.
On Condition Numbers for the Weighted Moore-Penrose Inverse and the Weighted Least Squares Problem involving Kronecker Products
Authors: Chen T. T. , Li W.
Published: February 2014

We establish some explicit expressions for norm-wise, mixed and componentwise condition numbers for the weighted Moore-Penrose inverse of a matrix A ⊗ B and more general matrix function compositions involving Kronecker products. The condition number for the weighted least squares problem (WLS) involving a Kronecker product is also discussed.
Molecular composition of biogenic secondary organic aerosols using ultrahigh-resolution mass spectrometry: comparing laboratory and field studies
Authors: Kourtchev I. , Fuller S. J. , Giorio C. , Healy R. M. , Wilson E. , O'Connor I. , Wenger J. C. , McLeod M. , Aalto J. , Ruuskanen T. M. , Maenhaut W. , Jones R. , Venables D. S. , Sodeau J. R. , Kulmala M. , Kalberer M.
Published: February 2014

Abstract. Numerous laboratory experiments have been performed in an attempt to mimic atmospheric secondary organic aerosol (SOA) formation. However, it is still unclear how close the aerosol particles generated in laboratory experiments resemble atmospheric SOA with respect to their detailed chemical composition. In this study, we generated SOA in a simulation chamber from the ozonolysis of α-pinene and a biogenic volatile organic compound (BVOC) mixture containing α- and β-pinene, Δ3-carene, and isoprene. The detailed molecular composition of laboratory-generated SOA was compared with that of background ambient aerosol collected at a boreal forest site (Hyytiälä, Finland) and an urban location (Cork, Ireland) using direct infusion nanoelectrospray ultrahigh-resolution mass spectrometry. Kendrick mass defect and van Krevelen approaches were used to identify and compare compound classes and distributions of the detected species. The laboratory-generated SOA contained a distinguishable group of dimers that was not observed in the ambient samples. The presence of dimers was found to be less pronounced in the SOA from the BVOC mixtures when compared to the one component precursor system. The molecular composition of SOA from both the BVOC mixture and α-pinene represented the overall composition of the ambient sample from the boreal forest site reasonably well, with 72.3 ± 2.5% (n = 3) and 69.1 ± 3.0% (n = 3) common ions, respectively. In contrast, large differences were found between the laboratory-generated BVOC samples and the ambient urban sample. To our knowledge this is the first direct comparison of molecular composition of laboratory-generated SOA from BVOC mixtures and ambient samples.
Determination and analysis of spectral aerosol optical properties by a multi-instrumental approach
Authors: Segura S. , Estellés V. , Titos G. , Lyamani H. , Utrillas M. P. , Zotter P. , Prévôt A. S. H. , Močnik G. , Alados-Arboledas L. , Martínez-Lozano J. A.
Published: February 2014

Abstract. Continuous in-situ measurements of aerosol optical properties where conducted from 20 June to 20 July in Granada (Spain) with a 7-wavelength Aethalometer, a Multi Angle Absorption Photometer, and a 3-wavelength integrating Nephelometer. The aim of this work is to describe a methodology to obtain the absorption coefficients (babs) for the different Aethalometer wavelengths. In this way, data have been compensated using algorithms which best estimate the compensation factors needed. Two empirical factors are used to infer the absorption coefficients from the Aethalometer measurements: C – the parameter describing the enhancement of absorption by particles in the filter matrix due to multiple scattering of light in the filter matrix; and f – the parameter compensating for non-linear loading effects in the filter matrix. Spectral dependence of f found in this study is not very strong. Values for the campaign lie in the range from 1.15 at 370 nm to 1.11 at 950 nm. Wavelength dependence in C proves to be more important, and also more difficult to calculate. The values obtained span from 3.40 at 370 nm to 4.35 at 950 nm. Furthermore, the temporal evolution of the Ångström exponent of absorption (αabs) and the single scattering albedo (ω0), is presented. On average αabs is around 1.1 ± 0.3, and ω0 is 0.78 ± 0.08 and 0.74 ± 0.09 at 370 and 950 nm, respectively. These are typical values for sites with a predominance of absorbing particles, and the urban measurement site in this study is such. The babs average values are of 16 ± 10 Mm−1 (at 370 nm) and 5 ± 3 Mm−1 (at 950 nm), respectively. Finally, differences between working days and Sunday have been further analyzed, obtaining higher babs and lower ω0 during week than on Sundays as a consequence of the influence of diesel traffic.
Natural ocean carbon cycle sensitivity to parameterizations of the recycling in a climate model
Authors: Romanou A. , Romanski J. , Gregg W. W.
Published: February 2014

Abstract. Sensitivities of the oceanic biological pump within the GISS (Goddard Institute for Space Studies ) climate modeling system are explored here. Results are presented from twin control simulations of the air–sea CO2 gas exchange using two different ocean models coupled to the same atmosphere. The two ocean models (Russell ocean model and Hybrid Coordinate Ocean Model, HYCOM) use different vertical coordinate systems, and therefore different representations of column physics. Both variants of the GISS climate model are coupled to the same ocean biogeochemistry module (the NASA Ocean Biogeochemistry Model, NOBM), which computes prognostic distributions for biotic and abiotic fields that influence the air–sea flux of CO2 and the deep ocean carbon transport and storage. In particular, the model differences due to remineralization rate changes are compared to differences attributed to physical processes modeled differently in the two ocean models such as ventilation, mixing, eddy stirring and vertical advection. GISSEH(GISSER) is found to underestimate mixed layer depth compared to observations by about 55% (10%) in the Southern Ocean and overestimate it by about 17% (underestimate by 2%) in the northern high latitudes. Everywhere else in the global ocean, the two models underestimate the surface mixing by about 12–34%, which prevents deep nutrients from reaching the surface and promoting primary production there. Consequently, carbon export is reduced because of reduced production at the surface. Furthermore, carbon export is particularly sensitive to remineralization rate changes in the frontal regions of the subtropical gyres and at the Equator and this sensitivity in the model is much higher than the sensitivity to physical processes such as vertical mixing, vertical advection and mesoscale eddy transport. At depth, GISSER, which has a significant warm bias, remineralizes nutrients and carbon faster thereby producing more nutrients and carbon at depth, which eventually resurfaces with the global thermohaline circulation especially in the Southern Ocean. Because of the reduced primary production and carbon export in GISSEH compared to GISSER, the biological pump efficiency, i.e., the ratio of primary production and carbon export at 75 m, is half in the GISSEH of that in GISSER, The Southern Ocean emerges as a key region where the CO2 flux is as sensitive to biological parameterizations as it is to physical parameterizations. The fidelity of ocean mixing in the Southern Ocean compared to observations is shown to be a good indicator of the magnitude of the biological pump efficiency regardless of physical model choice.
Temperature-dependence of planktonic metabolism in the Subtropical North Atlantic Ocean
Authors: García-Corral L. S. , Barber E. , Regaudie-de-Gioux A. , Sal S. , Holding J. , Agustí S. , Navarro N. , Serret P. , Mozetič P. , Duarte C. M.
Published: February 2014

Abstract. The temperature dependence of planktonic metabolism in the Subtropical North Atlantic Ocean was assessed on the basis of measurements of gross primary production (GPP), community respiration (CR) and net community production (NCP), as well as experimental assessments of the response of CR to temperature manipulations. Metabolic rates were measured at 68 stations along three consecutive longitudinal transects completed during the Malaspina 2010 Expedition, in three different seasons. Temperatures gradients were observed in depth and at basin and seasonal scale. The results showed seasonal variability in the metabolic rates, being the highest rates observed during the spring transect. The overall mean integrated GPP/CR ratio was of 1.39 ± 0.27 decreasing from winter to summer and the NCP for the Subtropical North Atlantic Ocean during this cruises, was net autotrophy (NCP > 0) in about two-thirds of the total sampled communities (68.2%). Here, we reported the activation energies describing the temperature-dependence of planktonic community metabolism, which generally was higher for CR than for GPP in the Subtropical North Atlantic Ocean, as the metabolic theory of ecology predicts. Also, we performed an assessment of the activation energies describing the responses to in situ temperature at field (EaCR = 1.64 ± 0.36 eV) and those derive experimentally by temperature manipulations (EaCR = 1.45 ± 0.6 eV), which showed a great consistency.
Physical controls on CH4 emissions from a newly flooded subtropical freshwater hydroelectric reservoir: Nam Theun 2
Authors: Deshmukh C. , Serça D. , Delon C. , Tardif R. , Demarty M. , Jarnot C. , Meyerfeld Y. , Chanudet V. , Guédant P. , Rode W. , Descloux S. , Guérin F.
Published: February 2014

Abstract. In the present study, we measured CH4 ebullition and diffusion with funnels and floating chambers in the footprint of an eddy-covariance system measuring CH4 emissions at high frequency (30 mn) in the Nam Theun 2 Reservoir, a recently impounded (in 2008) subtropical hydroelectric reservoir located in Lao PDR, southeast Asia. The EC fluxes were very consistent with the sum of the two terms measured independently (diffusive fluxes + ebullition = EC fluxes), indicating that the EC system picked-up both diffusive fluxes and ebullition from the reservoir. The EC system permitted to evidence a diurnal bimodal pattern of CH4 emissions anti-correlated with atmospheric pressure. During daytime, a large atmospheric pressure drop triggers CH4 ebullition (up to 100 mmol m–2 d–1) whereas at night, a more moderate peak of CH4 emission was recorded. As a consequence, fluxes during daytime were twice higher than during nighttime. A total of 4811 measurements of CH4 ebullition with submerged funnels at a weekly/fortnightly frequency were performed. The data set covers a water depth ranging from 0.4 to 16 m, and all types of flooded ecosystems. This dataset allowed to determine that ebullition depends mostly on water level change among many other variables tested. On average, ebullition was 8.5 ± 10.5 mmol m–2 d–1 (10–90 percentile range: 0.03–21.5 mmol m–2 d–1) and ranged from 0–201.7 mmol m–2 d–1. An artificial neural network model could explain up to 45% of variability of ebullition using total static pressure (sum of hydrostatic and atmospheric pressure), variations in the water level and atmospheric pressure, and bottom temperature as inputs. This model allowed extrapolation of CH4 ebullition at the reservoir scale and performing gap-filling over four years. Our results clearly showed a very high seasonality: 50% of the yearly CH4 ebullition occurs within four months of the warm dry season. Overall, ebullition contributed 60–80% of total emissions from the surface of the reservoir (disregarding downstream emissions) suggesting that ebullition is a major pathway in young hydroelectric reservoirs in the tropics.
PLASIM-ENTSem v1.0: a spatio-temporal emulator of future climate change for impacts assessment
Authors: Holden P. B. , Edwards N. R. , Garthwaite P. H. , Fraedrich K. , Lunkeit F. , Kirk E. , Labriet M. , Kanudia A. , Babonneau F.
Published: February 2014

Abstract. Many applications in the evaluation of climate impacts and environmental policy require detailed spatio-temporal projections of future climate. To capture feedbacks from impacted natural or socio-economic systems requires interactive two-way coupling, but this is generally computationally infeasible with even moderately complex general circulation models (GCMs). Dimension reduction using emulation is one solution to this problem, demonstrated here with the GCM PLASIM-ENTS (Planet Simulator coupled with the efficient numerical terrestrial scheme). Our approach generates temporally evolving spatial patterns of climate variables, considering multiple modes of variability in order to capture non-linear feedbacks. The emulator provides a 188-member ensemble of decadally and spatially resolved (~ 5° resolution) seasonal climate data in response to an arbitrary future CO2 concentration and non-CO2 radiative forcing scenario. We present the PLASIM-ENTS coupled model, the construction of its emulator from an ensemble of transient future simulations, an application of the emulator methodology to produce heating and cooling degree-day projections, the validation of the simulator (with respect to empirical data) and the validation of the emulator (with respect to high-complexity models). We also demonstrate the application to estimates of sea-level rise and associated uncertainty.
New method for assessing the potential hazardousness of glacial lakes in the Cordillera Blanca, Peru
Authors: Emmer A. , Vilímek V.
Published: February 2014

Abstract. This paper presents a new and easily repeatable objective method for assessing the potential hazardousness of glacial lakes within the Peruvian region of Cordillera Blanca (excluding ice-dammed lakes, which do not reach significant volumes in this region). The presented method was designed to meet four basic principles, which we considered as being crucial. These are: (a) principle of regional focus; (b) principle of objectivity; (c) principle of repeatability; and (d) principle of multiple results. Potential hazardousness is assessed based on a combination of decision trees for clarity and numerical calculation for objectivity. A total of seventeen assessed characteristics are used, of which seven have yet to be used in this context before. Also, several ratios and calculations are defined for the first time. We assume that it is not relevant to represent the overall potential hazardousness of a particular lake by one result (number), thus the potential hazardousness is described in the presented method by five separate results (representing five different glacial lake outburst flood scenarios). These are potentials for: (a) dam overtopping resulting from a dynamic slope movement into the lake; (b) dam overtopping following the flood wave originating in a lake situated upstream; (c) dam failure resulting from a dynamic slope movement into the lake; (d) dam failure following the flood wave originating in a lake situated upstream; and (e) dam failure following a heavy earthquake. All of these potentials theoretically range from 0 to 1. The presented method was verified on the basis of assessing the pre-flood conditions of seven lakes which have produced ten glacial lake outburst floods in the past and ten lakes which have not. A comparison of these results showed that the presented method successfully identifies the potentially hazardous lakes.
Modelling runoff from a Himalayan debris-covered glacier
Authors: Fujita K. , Sakai A.
Published: February 2014

Abstract. Although the processes by which glacial debris-mantles alter the melting of glacier ice have been well studied, the mass balance and runoff patterns of Himalayan debris-covered glaciers and the response of these factors to climate change are not well understood. Many previous studies have addressed mechanisms of ice melt under debris mantles by applying multiplicative parameters derived from field experiments, and other studies have calculated the details of heat conduction through the debris layer. However, those approaches cannot be applied at catchment scales because debris distributions are heterogeneous and difficult to measure. Here, we establish a runoff model for a Himalayan debris-covered glacier in which the spatial distribution of the thermal properties of the debris mantle is estimated from remotely sensed multi-temporal data. We validated the model for the Tsho Rolpa Glacial Lake–Trambau Glacier basin in the Nepal Himalaya, using hydro-meteorological observations obtained for a 3.5 yr period (1993–1996). We calculated long-term averages of runoff components for the period 1980–2007 using gridded reanalysis datasets. Our calculations suggest that excess meltwater from the debris-covered area contributes significantly to the total runoff, mainly because of its location at lower elevations. Uncertainties in runoff values due to estimations of the thermal properties and albedo of the debris-covered surface were assessed to be approximately 8% of the runoff from the debris-covered area. We evaluated the sensitivities of runoff components to changes in air temperature and precipitation. As expected, warmer air temperatures increase the total runoff by increasing the melting rate; however, increased precipitation slightly reduces the total runoff, as ice melting is suppressed by the increased snow cover and associated high albedo. The response of total runoff to changing precipitation is complex because of the different responses of individual components (glacier, debris, and ice-free terrain) to precipitation levels. The impact of air temperature on inter-annual variability is 23 times greater than that of precipitation.
GIS and remote sensing techniques for the assessment of land use change impact on flood hydrology: the case study of Yialias basin in Cyprus
Authors: Alexakis D. D. , Grillakis M. G. , Koutroulis A. G. , Agapiou A. , Themistocleous K. , Tsanis I. K. , Michaelides S. , Pashiardis S. , Demetriou C. , Aristeidou K. , Retalis A. , Tymvios F. , Hadjimitsis D. G.
Published: February 2014

Abstract. Floods are one of the most common natural disasters worldwide, leading to economic losses and loss of human lives. This paper highlights the hydrological effects of multi-temporal land use changes in flood hazard within the Yialias catchment area, located in central Cyprus. A calibrated hydrological model was firstly developed to describe the hydrological processes and internal basin dynamics of the three major subbasins, in order to study the diachronic effects of land use changes. For the implementation of the hydrological model, land use, soil and hydrometeorological data were incorporated. The climatic and stream flow data were derived from rain and flow gauge stations located in the wider area of the watershed basin. In addition, the land use and soil data were extracted after the application of object-oriented nearest neighbor algorithms of ASTER satellite images. Subsequently, the cellular automata (CA)–Markov chain analysis was implemented to predict the 2020 land use/land cover (LULC) map and incorporate it to the hydrological impact assessment. The results denoted the increase of runoff in the catchment area due to the recorded extensive urban sprawl phenomenon of the last decade.
The Mediterranean is getting saltier
Authors: Borghini M. , Bryden H. , Schroeder K. , Sparnocchia S. , Vetrano A.
Published: February 2014

Abstract. The deep waters of the Mediterranean Sea have been getting saltier and warmer for at least the past 40 yr at rates of about 0.015 and 0.04 °C per decade. Here we show that two processes contribute to these increases in temperature and salinity. On interannual time scales, deep water formation events in severe winters transmit increasingly salty intermediate waters into the deep water. The second process is a steady downward flux of heat and salt through the halocline-thermocline that connects the Levantine Intermediate Water with the deep water. We illustrate these two processes with observations from repeat surveys of the western Mediterranean basin we have made over the past 10 yr.