bluuebunny/crossref_metadata_2025 huggingface dataset:
Does active psychosis cause neurobiological pathology? A critical review of the neurotoxicity hypothesis
Authors: Rund B. R.
Published: September 2013

Background

Since the neurotoxicity hypothesis was launched in 1991, it has generated a great deal of interest and given rise to several studies investigating the validity of the hypothesis that being psychotic has a toxic effect on the brain. The toxicity argument is used to justify early treatment. This review attempts to assess the studies that have addressed the question: Does an active psychosis, indexed by the duration of untreated psychosis (DUP), cause neurobiological pathology?

Method

The validity of the hypothesis has been studied primarily by correlation analyses that assess whether there are significant correlations between DUP and changes in neurocognitive functioning or brain structure. In this review, relevant reports were identified by a literature survey.

Results

Of the 35 studies (33 papers) evaluated, six neurocognitive studies supported the hypothesis and 16 did not. Eight morphology studies supported the hypothesis and five did not. In general, the studies that did not support the neurotoxicity hypothesis were larger in size and had more adequate designs (longitudinal) than those that supported the hypothesis.

Conclusions

Overall, there is limited empirical evidence for the neurotoxicity hypothesis in the studies reviewed. However, it is possible that there is a threshold value for a toxic effect of psychosis, rather than a linear relationship between DUP and a neurotoxic effect, and that several of the studies evaluated did not have a long enough DUP to detect a toxic effect of active psychosis.
Some reductions of the spectral set conjecture to integers
Authors: DUTKAY DORIN ERVIN , LAI CHUN–KIT
Published: September 2013

The spectral set conjecture, also known as the Fuglede conjecture, asserts that every bounded spectral set is a tile and vice versa. While this conjecture remains open on${\mathbb R}^1$, there are many results in the literature that discuss the relations among various forms of the Fuglede conjecture on${\mathbb Z}_n$,${\mathbb Z}$and${\mathbb R}^1$and also the seemingly stronger universal tiling (spectrum) conjectures on the respective groups. In this paper, we clarify the equivalences between these statements in dimension one. In addition, we show that if the Fuglede conjecture on${\mathbb R}^1$is true, then every spectral set with rational measure must have a rational spectrum. We then investigate the Coven–Meyerowitz property for finite sets of integers, introduced in [1], and we show that if the spectral sets and the tiles in${\mathbb Z}$satisfy the Coven–Meyerowitz property, then both sides of the Fuglede conjecture on${\mathbb R}^1$are true.
Metastability and rapid convergence to quasi-stationary bar states for the two-dimensional Navier–Stokes equations
Authors: Beck Margaret , Wayne C. Eugene
Published: September 2013

Quasi-stationary, or metastable, states play an important role in two-dimensional turbulent fluid flows, where they often emerge on timescales much shorter than the viscous timescale, and then dominate the dynamics for very long time intervals. In this paper we propose a dynamical systems explanation of the metastability of an explicit family of solutions, referred to as bar states, of the two-dimensional incompressible Navier–Stokes equation on the torus. These states are physically relevant because they are associated with certain maximum entropy solutions of the Euler equations, and they have been observed as one type of metastable state in numerical studies of two-dimensional turbulence. For small viscosity (high Reynolds number), these states are quasi-stationary in the sense that they decay on the slow, viscous timescale. Linearization about these states leads to a time-dependent operator. We show that if we approximate this operator by dropping a higher-order, non-local term, it produces a decay rate much faster than the viscous decay rate. We also provide numerical evidence that the same result holds for the full linear operator, and that our theoretical results give the optimal decay rate in this setting.
Conical functions of purely imaginary order and argument
Authors: Dunster T. M.
Published: September 2013

Associated Legendre functions are studied for the case where the degree is in conical form −½ + iτ (τ real), and the order iμ and argument ix are purely imaginary (μ and x real). Conical functions in this form have applications to Fourier expansions of the eigenfunctions on a closed geodesic. Real-valued numerically satisfactory solutions are introduced which are continuous for all real x. Uniform asymptotic approximations and expansions are then derived for the cases where one or both of μ and τ are large; these results (which involve elementary, Airy, Bessel and parabolic cylinder functions) are uniformly valid for unbounded x.
Geometry of 1-lightlike submanifolds in anti-de Sitter n-space
Authors: Wang Zhigang , Pei Donghe , Chen Liang
Published: September 2013

In this paper we investigate the differential geometry of 1-lightlike submanifolds in anti-de Sitter n-space as an application of the theory of Legendrian singularities. Based on some theory of lightlike submanifolds, we also introduce the notion of 1-lightlike horospherical Gauss curvature, which is important for us to study the singularities of 1-lightlike horospherical hypersurfaces. Moreover, we discuss the related geometric property of 1-lightlike horospherical hypersurfaces in anti-de Sitter n-space.
On the solvability of mixed variational problems with solution-dependent sets of Lagrange multipliers
Authors: Matei Andaluzia
Published: September 2013

We study an abstract mixed variational problem, the set of the Lagrange multipliers being dependent on the solution. The problem consists of a system of a variational equation and a variational inequality. We prove the existence of the solution based on a fixed-point technique for weakly sequentially continuous maps. We then apply the abstract result to the weak solvability of a boundary-value problem that models the frictional contact between a cylindrical deformable body and a rigid foundation.
Detection and exploitation of functional dependencies for model generation
Authors: DE CAT BROES , BRUYNOOGHE MAURICE
Published: September 2013

Recent work in Answer Set Programming has integrated ideas from Constraint Programming. This has led to a new field called ASP Modulo CSP (CASP), in which the ASP language is enriched with constraint atoms representing constraint satisfaction problems. These constraints have a more compact grounding and are handled by a new generation of search algorithms. However, the burden is on the modeler to exploit these new constructs in his declarative problem specifications. Here, we explore how to remove this burden by automatically generating constraint atoms. We do so in the context of FO(·)IDP, a knowledge representation language that extends first-order logic with, among others, inductive definitions, arithmetic and aggregates. We uncover functional dependencies in declarative problem specifications with a theorem prover and exploit them with a transformation that introduces functions. Experimental evaluation shows that we obtain more compact groundings and better search performance.
The jobs puzzle: Taking on the challenge via controlled natural language processing
Authors: SCHWITTER ROLF
Published: September 2013

In this paper we take on Stuart C. Shapiro's challenge of solving the Jobs Puzzle automatically and do this via controlled natural language processing. Instead of encoding the puzzle in a formal language that might be difficult to use and understand, we employ a controlled natural language as a high-level specification language that adheres closely to the original notation of the puzzle and allows us to reconstruct the puzzle in a machine-processable way and add missing and implicit information to the problem description. We show how the resulting specification can be translated into an answer set program and be processed by a state-of-the-art answer set solver to find the solutions to the puzzle.
Compiling Input* FO(·) inductive definitions into tabled prolog rules for IDP3
Authors: JANSEN JOACHIM , JORISSEN ALBERT , JANSSENS GERDA
Published: September 2013

FO(·)IDP3 extends first-order logic with inductive definitions, partial functions, types and aggregates. Its model generator IDP3 first grounds the theory and then uses search to find the models. The grounder uses Lifted Unit Propagation (LUP) to reduce the size of the groundings of problem specifications in IDP3. LUP is in general very effective, but performs poorly on definitions of predicates whose two-valued interpretation can be computed from data in the input structure. To solve this problem, a preprocessing step is introduced that converts such definitions to Prolog code and uses XSB Prolog to compute their interpretation. The interpretation of these predicates is then added to the input structure, their definitions are removed from the theory and further processing is done by the standard IDP3 system. Experimental results show the effectiveness of our method.
Logic programming with function symbols: Checking termination of bottom-up evaluation through program adornments
Authors: GRECO SERGIO , MOLINARO CRISTIAN , TRUBITSYNA IRINA
Published: September 2013

Recent years have witnessed an increasing interest in enhancing answer set solvers by allowing function symbols. Since the introduction of function symbols makes common inference tasks undecidable, research has focused on identifying classes of programs allowing only a restricted use of function symbols while ensuring decidability of common inference tasks. Finitely-ground programs, introduced in Calimeri et al. (2008), are guaranteed to admit a finite number of stable models with each of them of finite size. Stable models of such programs can be computed and thus common inference tasks become decidable. Unfortunately, checking whether a program is finitely-ground is semi-decidable. This has led to several decidable criteria, called termination criteria, providing sufficient conditions for a program to be finitely-ground. This paper presents a new technique that, used in conjunction with current termination criteria, allows us to detect more programs as finitely-ground. Specifically, the proposed technique takes a logic program ${\cal P}$ and transforms it into an adorned program ${{\cal P}}$μ with the aim of applying termination criteria to ${{\cal P}}$μ rather than ${\cal P}$. The transformation is sound in that if the adorned program satisfies a certain termination criterion, then the original program is finitely-ground. Importantly, applying termination criteria to adorned programs rather than the original ones strictly enlarges the class of programs recognized as finitely-ground.
Fuzzy answer sets approximations
Authors: ALVIANO MARIO , PEÑALOZA RAFAEL
Published: September 2013

Fuzzy answer set programming (FASP) is a recent formalism for knowledge representation that enriches the declarativity of answer set programming by allowing propositions to be graded. To now, no implementations of FASP solvers are available and all current proposals are based on compilations of logic programs into different paradigms, like mixed integer programs or bilevel programs. These approaches introduce many auxiliary variables which might affect the performance of a solver negatively. To limit this downside, operators for approximating fuzzy answer sets can be introduced: Given a FASP program, these operators compute lower and upper bounds for all atoms in the program such that all answer sets are between these bounds. This paper analyzes several operators of this kind which are based on linear programming, fuzzy unfounded sets and source pointers. Furthermore, the paper reports on a prototypical implementation, also describing strategies for avoiding computations of these operators when they are guaranteed to not improve current bounds. The operators and their implementation can be used to obtain more constrained mixed integer or bilevel programs, or even for providing a basis for implementing a native FASP solver. Interestingly, the semantics of relevant classes of programs with unique answer sets, like positive programs and programs with stratified negation, can be already computed by the prototype without the need for an external tool.
BigYAP: Exo-compilation meets UDI
Authors: SANTOS COSTA VÍTOR , VAZ DAVID
Published: September 2013

The widespread availability of large data-sets poses both an opportunity and a challenge to logic programming. A first approach is to couple a relational database with logic programming, say, a Prolog system with MySQL. While this approach does pay off in cases where the data cannot reside in main memory, it is known to introduce substantial overheads. Ideally, we would like the Prolog system to deal with large data-sets in an efficient way both in terms of memory and of processing time. Just In Time Indexing (JITI) was mainly motivated by this challenge, and can work quite well in many application.

Exo-compilation, designed to deal with large tables, is a next step that achieves very interesting results, reducing the memory footprint over two thirds. We show that combining exo-compilation with Just In Time Indexing can have significant advantages both in terms of memory usage and in terms of execution time.

An alternative path that is relevant for many applications is User-Defined Indexing (UDI). This allows the use of specialized indexing for specific applications, say the spatial indexing crucial to any spatial system. The UDI sees indexing as pluggable modules, and can naturally be combined with Exo-compilation. We do so by using UDI with exo-data, and incorporating ideas from the UDI into high-performance indexers for specific tasks.
A declarative approach to distributed computing: Specification, execution and analysis
Authors: MA JIEFEI , LE FRANCK , WOOD DAVID , RUSSO ALESSANDRA , LOBO JORGE
Published: September 2013

There is an increasing interest in using logic programming to specify and implement distributed algorithms, including a variety of network applications. These are applications where data and computation are distributed among several devices and where, in principle, all the devices can exchange data and share the computational results of the group. In this paper we propose a declarative approach to distributed computing whereby distributed algorithms and communication models can be (i) specified as action theories of fluents and actions; (ii) executed as collections of distributed state machines, where devices are abstracted as (input/output) automata that can exchange messages; and (iii) analysed using existing results on connecting causal theories and Answer Set Programming. Results on the application of our approach to different classes of network protocols are also presented.
A Meta-Analysis of Interviews and Cognitive Ability
Authors: Roth Philip L. , Huffcutt Allen I.
Published: September 2013

The topic of what interviews measure has received a great deal of attention over the years. One line of research has investigated the relationship between interviews and the construct of cognitive ability. A previous meta-analysis reported an overall corrected correlation of .40 ( Huffcutt, Roth, & McDaniel, 1996 ). A more recent meta-analysis reported a noticeably lower corrected correlation of .27 ( Berry, Sackett, & Landers, 2007 ). After reviewing both meta-analyses, it appears that the two studies posed different research questions. Further, there were a number of coding judgments in Berry et al. that merit review, and there was no moderator analysis for educational versus employment interviews. As a result, we reanalyzed the work by Berry et al. and found a corrected correlation of .42 for employment interviews (.15 higher than Berry et al., a 56% increase). Further, educational interviews were associated with a corrected correlation of .21, supporting their influence as a moderator. We suggest a better estimate of the correlation between employment interviews and cognitive ability is .42, and this takes us “back to the future” in that the better overall estimate of the employment interviews – cognitive ability relationship is roughly .40. This difference has implications for what is being measured by interviews and their incremental validity.
Hiring Gender-Occupation Incongruent Applicants
Authors: Frauendorfer Denise , Schmid Mast Marianne
Published: September 2013

Gender-occupational stereotypes that recruiters harbor toward male and female applicants still exist. However, there might be individual differences in recruiters that account for more or less stereotyping when facing male and female applicants who do not correspond to attributes of the job opening (e.g., male-typical vs. female-typical job). In this study, we tested whether recruiters high on interpersonal sensitivity are more likely to hire gender-occupational incongruent applicants. Seventy-three participants in the role of a recruiter conducted a job interview with either a gender-occupational incongruent (woman applying for a male-typical job or man applying for a female-typical job) or a gender-occupational congruent applicant. Results showed that the likelihood of hiring a gender-occupation incongruent applicant increased the more the recruiter was interpersonally sensitive, whereas interpersonal sensitivity did not affect hiring decision regarding gender-occupation congruent applicants.
Performance Appraisal Satisfaction
Authors: Culbertson Satoris S. , Henning Jaime B. , Payne Stephanie C.
Published: September 2013

Employee satisfaction with performance appraisal (PA) plays a large role in the perceived effectiveness of PA. We examined the joint effects of feedback sign (positive or negative) and three goal orientation dimensions (learning, performance-prove, performance-avoid) on PA satisfaction. Results revealed the negative relationship between negative feedback and PA satisfaction was stronger for those higher in performance-prove (PPGO), performance-avoid, and learning goal orientation. Additionally, the relationship between positive feedback and PA satisfaction was stronger for individuals low on PPGO and weaker for individuals high on PPGO. Implications for enhancing PA reactions are discussed.
Cerebral Hemodynamic and Ventilatory Responses to Hypoxia, Hypercapnia, and Hypocapnia during 5 Days at 4,350 m
Authors: Rupp Thomas , Esteve François , Bouzat Pierre , Lundby Carsten , Perrey Stéphane , Levy Patrick , Robach Paul , Verges Samuel
Published: September 2013

This study investigated the changes in cerebral near-infrared spectroscopy (NIRS) signals, cerebrovascular and ventilatory responses to hypoxia and CO2 during altitude exposure. At sea level (SL), after 24 hours and 5 days at 4,350 m, 11 healthy subjects were exposed to normoxia, isocapnic hypoxia, hypercapnia, and hypocapnia. The following parameters were measured: prefrontal tissue oxygenation index (TOI), oxy- (HbO2), deoxy- and total hemoglobin (HbTot) concentrations with NIRS, blood velocity in the middle cerebral artery (MCAv) with transcranial Doppler and ventilation. Smaller prefrontal deoxygenation and larger ΔHbTot in response to hypoxia were observed at altitude compared with SL (day 5: ΔHbO2−0.6±1.1 versus −1.8±1.3  μmol/cmper mm Hg and ΔHbTot 1.4±1.3 versus 0.7±1.1  μmol/cm per mm Hg). The hypoxic MCAv and ventilatory responses were enhanced at altitude. Prefrontal oxygenation increased less in response to hypercapnia at altitude compared with SL (day 5: ΔTOI 0.3±0.2 versus 0.5±0.3% mm Hg). The hypercapnic MCAv and ventilatory responses were decreased and increased, respectively, at altitude. Hemodynamic responses to hypocapnia did not change at altitude. Short-term altitude exposure improves cerebral oxygenation in response to hypoxia but decreases it during hypercapnia. Although these changes may be relevant for conditions such as exercise or sleep at altitude, they were not associated with symptoms of acute mountain sickness.
Lab on a Biomembrane: Rapid prototyping and manipulation of 2D fluidic lipid bilayer circuits
Authors: Ainla Alar , Gözen Irep , Hakonen Bodil , Jesorka Aldo
Published: September 2013

Lipid bilayer membranes are among the most ubiquitous structures in the living world, with intricate structural features and a multitude of biological functions. It is attractive to recreate these structures in the laboratory, as this allows mimicking and studying the properties of biomembranes and their constituents and to specifically exploit the intrinsic two-dimensional fluidity. Even though diverse strategies for membrane fabrication have been reported, the development of related applications and technologies has been hindered by the unavailability of both versatile and simple methods. Here we report a rapid prototyping technology for two-dimensional fluidic devices, based on in-situ generated circuits of phospholipid films. In this “lab on a molecularly thin membrane”, various chemical and physical operations, such as writing, erasing, functionalization and molecular transport, can be applied to user-defined regions of a membrane circuit. This concept is an enabling technology for research on molecular membranes and their technological use.
Silver-catalyzed oxidative coupling/cyclization of acrylamides with 1,3-dicarbonyl compounds
Authors: Wang Hua , Guo Li-Na , Duan Xin-Hua
Published: September 2013

An efficient silver-catalyzed oxidative cyclization of acrylamides with 1,3-dicarbonyl compounds is described. It proceeds through a tandem radical addition/cyclization process, in which two new C–C bonds were formed.
Mycobacterium smegmatis Ku binds DNA without free ends
Authors: Kushwaha Ambuj K. , Grove Anne
Published: September 2013

Ku is central to the non-homologous end-joining pathway of double-strand-break repair in all three major domains of life, with eukaryotic homologues being associated with more diversified roles compared with prokaryotic and archaeal homologues. Ku has a conserved central ‘ring-shaped’ core domain. While prokaryotic homologues lack the N- and C-terminal domains that impart functional diversity to eukaryotic Ku, analyses of Ku from certain prokaryotes such as Pseudomonas aeruginosa and Mycobacterium smegmatis have revealed the presence of distinct C-terminal extensions that modulate DNA-binding properties. We report in the present paper that the lysine-rich C-terminal extension of M. smegmatis Ku contacts the core protein domain as evidenced by an increase in DNA-binding affinity and a decrease in thermal stability and intrinsic tryptophan fluorescence upon its deletion. Ku deleted for this C-terminus requires free DNA ends for binding, but translocates to internal DNA sites. In contrast, full-length Ku can directly bind DNA without free ends, suggesting that this property is conferred by its C-terminus. Such binding to internal DNA sites may facilitate recruitment to sites of DNA damage. The results of the present study also suggest that extensions beyond the shared core domain may have independently evolved to expand Ku function.
Solution structures of the Bacillus cereus metallo-β-lactamase BcII and its complex with the broad spectrum inhibitor R-thiomandelic acid
Authors: Karsisiotis Andreas Ioannis , Damblon Christian F. , Roberts Gordon C. K.
Published: September 2013

Metallo-β-lactamases, enzymes which inactivate β-lactam antibiotics, are of increasing biological and clinical significance as a source of antibiotic resistance in pathogenic bacteria. In the present study we describe the high-resolution solution NMR structures of the Bacillus cereus metallo-β-lactamase BcII and of its complex with R-thiomandelic acid, a broad-spectrum inhibitor of metallo-β-lactamases. This is the first reported solution structure of any metallo-β-lactamase. There are differences between the solution structure of the free enzyme and previously reported crystal structures in the loops flanking the active site, which are important for substrate and inhibitor binding and catalysis. The binding of R-thiomandelic acid and the roles of active-site residues are defined in detail. Changes in the enzyme structure upon inhibitor binding clarify the role of the mobile β3–β4 loop. Comparisons with other metallo-β-lactamases highlight the roles of individual amino-acid residues in the active site and the β3–β4 loop in inhibitor binding and provide information on the basis of structure–activity relationships among metallo-β-lactamase inhibitors.
Ultra‐wideband tapered slot antenna with dual band‐notched characteristics
Authors: Lee Dae Heon , Yang Hae‐Yong , Cho Young‐Ki
Published: September 2013

A novel tapered slot antenna (TSA) with 3.5/5.5 GHz dual band‐notched characteristics for ultra‐wideband radios is proposed in this study. To realise dual band‐notched characteristics at the TSA, the author employ (a) a pair of nested C‐shaped stubs beside the feed line and (b) a broadband microstrip‐slotline transition with an Archimedean spiral‐shaped slot. The proposed antenna has been successfully simulated, implemented and measured. Measured data for the optimised case show the bandwidth for the voltage standing wave ratio < 2 to be 9.2 GHz (from 2.4 to 11.6 GHz) with two notched bands of 3.1–4.0 GHz (world interoperability for microwave access band) and 5.1–6.2 GHz (wireless local area network band), respectively. The measured electrical parameters of the proposed antenna and its radiation patterns show excellent performance with good pulse handling capabilities. Also, the 3.5/5.5 GHz dual band‐notched characteristics are achieved without increasing the size of the single band‐notched TSA reported previously.
Active and reactive power regulation in grid connected wind energy systems with permanent magnet synchronous generator and matrix converter
Authors: Rajendran Santhi , Govindarajan Uma , Parvathi Sankar Deiva Sundari
Published: September 2013

This study presents a simple voltage oriented vector control scheme to regulate active and reactive power in a grid connected variable speed wind electrical system that consists of permanent magnet synchronous generator and matrix converter, which enables the maximum power tracking in wind electrical systems. The maximum extractable power from wind is derived from power curves and set as reference active power. Reactive power reference is chosen as zero. The deviations in powers are processed by proportional and integral (PI) controllers which vary the voltage gain of MC through which the desired regulation of powers is carried out. Since the relationship between wind speed and reference active power is nonlinear, single PI controller is insufficient, hence gain scheduling is required to adjust the controller parameters in response to changes in wind speeds. The controller parameter change is abrupt in conventional gain scheduling which leads to unstable performance. To avoid this, neural network‐based PI (NN‐PI) is designed which is more robust. In the presented work, both conventional gain scheduled PI and NN‐PI are applied to validate the suggested voltage oriented control for power regulation. Simulation and experimental studies are presented to confirm the effective functionality of the system.
Electronic structure and excited state dynamics in optically excited PTCDA films investigated with two-photon photoemission
Authors: Marks M. , Sachs S. , Schwalb C. H. , Schöll A. , Höfer U.
Published: September 2013

We present an investigation of the electronic structure and excited state dynamics of optically excited 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) thin films adsorbed on Ag(111) using two-photon photoemission spectroscopy (2PPE). 2PPE allows us to study both occupied and unoccupied electronic states, and we are able to identify signals from the highest occupied and the two lowest unoccupied electronic states of the PTCDA thin film in the 2PPE spectra. The energies for occupied states are identical to values from ultraviolet photoelectron spectroscopy. Compared to results from inverse photoelectron spectroscopy (IPES), the 2PPE signals from the two lowest unoccupied electronic states, LUMO and LUMO+1, are found at 0.8 eV and 1.0 eV lower energies, respectively. We attribute this deviation to the different final states probed in 2PPE and IPES and the attractive interaction of the photoexcited electron and the remaining hole. Furthermore, we present a time-resolved investigation of the excited state dynamics of the PTCDA film in the femtosecond time regime. We observe a significantly shorter inelastic excited state lifetime compared to findings from time-resolved photoluminescence spectroscopy of PTCDA single crystals which could originate from excitation quenching by the metal substrate.
Atomistic simulations of methane interactions with an atmospheric moisture
Authors: Galashev Alexander Y.
Published: September 2013

Methane is an extremely effective absorber of radiation, i.e., it is a relatively potent greenhouse gas, and the increased concentration of methane in the atmosphere must influence earth's radiation balance. The adsorption of one to six methane molecules by water clusters is studied by the method of molecular dynamics under near-atmospheric conditions. The capture of methane molecules by water clusters produces an increase in the integrated intensity of IR absorbance and the reflection coefficient. The Raman spectrum of the system is considerably depleted due to the addition of methane molecules to the disperse water system. The observed emission power of a dispersed aqueous system with adsorbed methane molecules has appreciably increased relative to the analogous characteristics of the pure water cluster system. The Voronoi polyhedra and simplified ones constructed within the framework of molecular-dynamic model of clusters are used for the analysis of the structure changes occurring with increasing the number of adsorbed CH4 molecules.
Assessing the non-ideality of the CO2-CS2 system at molecular level: A Raman scattering study
Authors: Besnard M. , Cabaço M. I. , Coutinho J. A. P. , Danten Y.
Published: September 2013

The dense phase of CO2-CS2 mixtures has been analysed by Raman spectroscopy as a function of the CO2 concentration (0.02–0.95 mole fractions) by varying the pressure (0.5 MPa up to 7.7 MPa) at constant temperature (313 K). The polarised and depolarised spectra of the induced (ν2, ν3) modes of CS2 and of the ν1-2ν2 Fermi resonance dyad of both CO2 and CS2 have been measured. Upon dilution with CO2, the evolution of the spectroscopic observables of all these modes displays a “plateau-like” region in the CO2 mole fraction 0.3–0.7 never previously observed in CO2-organic liquids mixtures. The bandshape and intensity of the induced modes of CS2 are similar to those of pure CS2 up to equimolar concentration, after which variations occur. The preservation of the local ordering from pure CS2 to equimolar concentration together with the non-linear evolution of the spectroscopic observables allows inferring that two solvation regimes exist with a transition occurring in the plateau domain. In the first regime, corresponding to CS2 concentrated mixtures, the liquid phase is segregated with dominant CS2 clusters, whereas, in the second one, CO2 monomers and dimers and CO2-CS2 hetero-dimers coexist dynamically on a picosecond time-scale. It is demonstrated that the subtle interplay between attractive and repulsive interactions which provides a molecular interpretation of the non-ideality of the CO2-CS2 mixture allows rationalizing the volume expansion and the existence of the plateau-like region observed in the pressure-composition diagram previously ascribed to the proximity of an upper critical solution temperature at lower temperatures.
Gyro-induced acceleration of magnetic reconnection
Authors: Comisso L. , Grasso D. , Waelbroeck F. L. , Borgogno D.
Published: September 2013

The linear and nonlinear evolution of magnetic reconnection in collisionless high-temperature plasmas with a strong guide field is analyzed on the basis of a two-dimensional gyrofluid model. The linear growth rate of the reconnecting instability is compared to analytical calculations over the whole spectrum of linearly unstable wave numbers. In the strongly unstable regime (large Δ′), the nonlinear evolution of the reconnecting instability is found to undergo two distinctive acceleration phases separated by a stall phase in which the instantaneous growth rate decreases. The first acceleration phase is caused by the formation of strong electric fields close to the X-point due to ion gyration, while the second acceleration phase is driven by the development of an open Petschek-like configuration due to both ion and electron temperature effects. Furthermore, the maximum instantaneous growth rate is found to increase dramatically over its linear value for decreasing diffusion layers. This is a consequence of the fact that the peak instantaneous growth rate becomes weakly dependent on the microscopic plasma parameters if the diffusion region thickness is sufficiently smaller than the equilibrium magnetic field scale length. When this condition is satisfied, the peak reconnection rate asymptotes to a constant value.
Surface plasmon polaritons on soft-boundary graphene nanoribbons and their application in switching/demultiplexing
Authors: Forati Ebrahim , Hanson George W.
Published: September 2013

A graphene sheet gated with a ridged ground plane, creating a soft-boundary graphene nanoribbon, is considered. By adjusting the ridge parameters and bias voltage a channel can be created on the graphene which can guide transverse magnetic surface plasmon polaritons. Two types of modes are found; fundamental and higher-order modes with no apparent cutoff frequency and with energy distributed over the created channel, and edge modes with energy concentrated at the soft-boundary edge. Dispersion curves, electric near-field patterns, and current distributions of these modes are determined. Since the location where energy is concentrated in the edge modes can be easily controlled electronically by the bias voltage and frequency, the edge-mode phenomena is used to propose a voltage controlled plasmonic switch and a plasmonic frequency demultiplexer.
Spin-wave nonreciprocity based on interband magnonic transitions
Authors: Di K. , Lim H. S. , Zhang V. L. , Ng S. C. , Kuok M. H.
Published: September 2013

We theoretically demonstrate linear spin-wave nonreciprocity in a Ni80Fe20 nanostripe waveguide, based on interband magnonic transitions induced by a time-reversal and spatial-inversion symmetry breaking magnetic field. An analytical coupled-mode theory of spin waves, developed to describe the transitions which are accompanied by simultaneous frequency and wavevector shifts of the coupled spin waves, is well corroborated by numerical simulations. Our findings could pave the way for the realization of spin-wave isolation and the dynamic control of spin-wave propagation in nanoscale magnonic integrated circuits via an applied magnetic field.
Highly efficient poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/Si hybrid solar cells with imprinted nanopyramid structures
Authors: Chen Jheng-Yuan , Yu Ming-Hung , Chang Shun-Fa , Wen Sun Kien
Published: September 2013

High-efficiency hybrid solar cells based on nanostructured silicon and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), which were fabricated via a simple nanoimprint fabrication process, demonstrated an excellent power conversion efficiency of 10.86%. The complex and costly high-temperature photolithography and masking steps were replaced by techniques that are low-cost and capable of mass production. The nanopyramid structures fabricated on the silicon surface provided an antireflective effect and have a radial junction architecture that enhanced the light absorption and carrier collection efficiency. The short-circuit current density (Jsc) of the hybrid solar cell with nanopyramid structures was greatly improved from 24.5 mA/cm2 to 32.5 mA/cm2 compared with that of a flat surface device. The highest solar cell efficiency was achieved on a 525 μm-thick 2.3 Ω cm n-type Czochralski process (CZ) Si substrate with a designated area of 4 cm2.
Coupling of spin and vibrational degrees of freedom of adsorbates at metal surfaces probed by vibrational sum-frequency generation
Authors: Öström H. , Krenz M. , Radu I. , Bovensiepen U. , Wolf M. , Frischkorn C.
Published: September 2013

Vibrational spectroscopy using sum-frequency generation has been used to investigate the coupling between a ferromagnetic thin film and adsorbed molecules, here CO on Ni/Cu(100). The CO stretching vibration exhibits a strong magnetic contrast with a pronounced temperature dependence, underlining the high sensitivity of this adsorbate-specific spectroscopy method. Our results indicate that the strong temperature dependence is caused by dynamical changes in the surface chemical bond when the CO stretch vibration is coupled to thermally excited external vibrational modes.
Improved Nb SIS devices for heterodyne mixers between 700 GHz and 1.3 THz with NbTiN transmission lines using a normal metal energy relaxation layer
Authors: Westig M. P. , Selig S. , Jacobs K. , Klapwijk T. M. , Honingh C. E.
Published: September 2013

In this paper, we demonstrate experimentally the implementation of a niobium-trilayer junction with an aluminum-oxide tunnel barrier, embedded in a high-gap superconducting niobium-titanium-nitride circuit. Previously reported heating by quasiparticle trapping is removed by inserting a normal metal layer of gold between the niobium junction and the niobium-titanium-nitride layer. We analyze in dc-characterization measurements the cooling of the nonequilibrium quasiparticles in various device geometries having different gold layer thickness and shape. Our work is concluded with remarks for future heterodyne mixer experiments using our device technology.
Charging process of polyurethane based composites under electronic irradiation: Effects of cellulose fiber content
Authors: Hadjadj Aomar , Jbara Omar , Tara Ahmed , Gilliot Mickael , Dellis Jean-Luc
Published: September 2013

The study deals with the charging effect of polyurethanes-based composites reinforced with cellulose fibers, under electronic beam irradiation in a scanning electron microscope. The results indicate that the leakage current and the trapped charge as well as the kinetics of charging process significantly change beyond a critical concentration of 10% cellulose fibers. These features are correlated with the cellulose concentration-dependence of the electrical properties, specifically resistivity and capacitance, of the composite.
Multi objective optimization of solid oxide fuel cell stacks considering parameter effects: Fuel utilization and hydrogen cost
Authors: Behzadi Forough Atefeh , Roshandel Ramin
Published: September 2013

In the context of stationary power generation, fuel cell based systems are being predicted as a valuable option to tabernacle the thermodynamic cycle based power plants. In this paper, multi objective optimization approach is used to optimize the planer solid oxide fuel cell (SOFC) stacks performance using genetic algorithm technique. Multi objective optimization generates the most attractive operating conditions of a SOFC system. This allows performing the optimization of the system regarding to two different objectives. Two pairs of different objectives are considered in this paper as distinguished strategies. In the first strategy, minimization of the breakeven per-unit energy cost ($/kWh) and maximization of the output power is considered. Similarly, two other objectives are also considered in the second strategy as minimization of the breakeven per-unit energy cost ($/kWh) and maximization of the electrical efficiency. Optimization of the first strategy predicts a maximum power output of 108.33 kW at a breakeven per-unit energy cost of 0.51 $/kWh and minimum breakeven per-unit energy cost of 0.30 $/kWh at a power of 42.18 kW. In the second strategy, maximum efficiency of 63.93% at a breakeven per-unit energy cost of 0.42$/kWh is predicted, while minimum breakeven per-unit energy cost of 0.25 $/kWh at efficiency of 48.3% is obtained. At the end, evaluation of parameter effects on multi objective optimization regarding different hydrogen costs and fuel utilization factors are presented. It is worthy to note that the sensitivity analysis for multi objective optimization can be considered both as an advanced analysis tool and as support to technology managers, engineers, and decision makers when working by such as systems.
Correlation between optical absorption redshift and carrier density in phase change materials
Authors: Ho H. W. , Song W. D. , Bai K. , Branicio P. S. , Tan Teck L. , Ji R. , Law L. T. , Ng C. M. , Wang L.
Published: September 2013

Here, we report an optical absorption redshift map for GeTe-Sb2Te3 pseudo-binary alloys. We found that, with phase change from amorphous to crystalline, the observed redshift increases with Ge concentration along pseudo-line of compositions, which directly reflects the enhanced electron delocalization/resonant bonding and increased carrier concentrations in the respective crystal compounds. The measured valence band maximum shift towards the Fermi energy from amorphous to crystalline phase supports the observed similar trend in redshift and carrier density. We show that the correlation between optical redshift and carrier density, attributed to the resonant bonding, can be rationalized by calculating the valence electron concentration, the ionicity, and hybridization.
Dual-wavelength laser with topological charge
Authors: Yu Haohai , Xu Miaomiao , Zhao Yongguang , Wang Yicheng , Han Shuo , Zhang Huaijin , Wang Zhengping , Wang Jiyang
Published: September 2013

We demonstrate the simultaneous oscillation of different photons with equal orbital angular momentum in solid-state lasers for the first time to our knowledge. Single tunable Hermite-Gaussian (HG0,n) (0 ≤ n ≤ 7) laser modes with dual wavelength were generated using an isotropic cavity. With a mode-converter, the corresponding Laguerre-Gaussian (LG0,n) laser modes were obtained. The oscillating laser modes have two types of photons at the wavelengths of 1077 and 1081 nm and equal orbital angular momentum of nħ per photon. These results identify the possibility of simultaneous oscillation of different photons with equal and controllable orbital angular momentum. It can be proposed that this laser should have promising applications in many fields based on its compact structure, tunable orbital angular momentum, and simultaneous oscillation of different photons with equal orbital angular momentum.
Reproductive biology of the dusky grouper (Epinephelus marginatus) at the southern limit of its distribution in the south-western Atlantic
Authors: Condini Mario V. , Fávaro Luís F. , Varela Antonio S. , Garcia Alexandre M.
Published: September 2013

We investigated the reproductive parameters of a dusky grouper Epinephelus marginatus population at the southern limit of its distribution in the south-western Atlantic. The analysed specimens were captured between January 2008 and April 2011 at Carpinteiro Bank (CB) (32°16′S; 051°47′W), a seamount located at the 20 m isobath ~16 nautical miles from the coast. The gonads of a total of 201 individuals (184 females, 16 males and 1 individual in sexual transition) with a total length (TL, mm) between 278 and 1160 mm were analysed microscopically. Histological analyses of the gonads suggested that the species is a partial spawner with a long spawning period (between November and March) and with a reproductive peak between November and January. The average female length at first maturity (L50) was 496 (TL, mm). We also observed partially spawned ovaries and partially spawned testes, which indicated reproductive activity, and we noted the presence of hyalinised follicles. These findings reveal that CB is the southernmost portion of the south-western Atlantic in which the dusky grouper reproduces. Additionally, an inshore-offshore comparison suggested that deeper (>20 m) rocky bottoms, such as the studied seamount, constitute higher quality habitats for this species when compared with littoral (<5 m) rocky reefs.
Diagnostic leukapheresis enables reliable detection of circulating tumor cells of nonmetastatic cancer patients
Authors: Fischer Johannes C. , Niederacher Dieter , Topp Stefan A. , Honisch Ellen , Schumacher Sarah , Schmitz Norma , Zacarias Föhrding Luisa , Vay Christian , Hoffmann Imke , Kasprowicz Nikola S. , Hepp Philip G. , Mohrmann Svjetlana , Nitz Ulrike , Stresemann Antje , Krahn Thomas , Henze Tanja , Griebsch Evelyn , Raba Katharina , Rox Jutta M. , Wenzel Folker , Sproll Christoph , Janni Wolfgang , Fehm Tanja , Klein Christoph A. , Knoefel Wolfram Trudo , Stoecklein Nikolas H.
Published: September 2013

Significance

The infrequent detection of circulating tumor cells (CTCs) has hindered their clinical implication and their potential use in the sense of a “liquid biopsy” for cancer diagnosis and therapy. Hypothesizing that the limited blood volume commonly used for CTC analysis (1–10 mL) accounts for variable detection rates, we used leukapheresis to screen large blood volumes for CTCs. This enabled a more reliable detection of CTCs at high frequency even in nonmetastatic cancer patients. Thus, diagnostic leukapheresis may facilitate the routine clinical use of CTCs as biomarkers for personalized medicine. Combined with technologies for single-cell molecular genetics or cell biology, it may significantly improve prediction of therapy response and monitoring, especially in early systemic cancer.
Introduction
Authors: Maslin Mark
Published: September 2013

The ‘Introduction’ explains that global warming is the most important science issue of the 21st century, challenging the very structure of our global society. The problem is that global warming is not just a scientific concern, but encompasses economics, sociology, geopolitics, local politics, and individuals' choice of lifestyle. Global warming is caused by the massive increase of greenhouse gases, such as carbon dioxide, in the atmosphere, resulting from the burning of fossil fuels and deforestation. An overview of the following chapters is provided.
What is the evidence for climate change?
Authors: Maslin Mark
Published: September 2013

‘What is the evidence for climate change?’ considers both past and recent climate change through changes in temperature, precipitation, and relative global sea level to show that significant changes in climate have been recorded. These include a 0.74°C increase in average global temperatures over the last 100 years, sea-level rise of over 40mm, significant shifts in the seasonality and intensities of precipitation, changing weather patterns, and significant retreat of Arctic sea ice and nearly all continental glaciers. The Intergovernmental Panel on Climate Change (IPCC) 2007 report states that the evidence for global warming is unequivocal and there is very high confidence that this warming is due to human activity.
Solutions
Authors: Maslin Mark
Published: September 2013

‘Solutions’ examines two types of solution to global warming. First is adaptation, as we already know that there will be climate change even if we reduce our emissions back to 1990 levels. Second is mitigation, which is concerned with reversing this trend and cutting greenhouse gas emissions. Scientists believe a cut of between 60% and 80% in carbon dioxide emissions is required to prevent the worst effects of global warming. This will require regulatory, technological, and economic solutions. Fossil fuels need to be replaced with renewable or alternative energy sources — biomass fuels, geothermal energy, hydroenergy, nuclear fusion and fission, solar energy, wave power, and wind power.