bluuebunny/crossref_metadata_2025 huggingface dataset:
The Us Primary System: Could it Work in Europe?
Authors: Lloyd Lindsay
Published: July 2013

This article examines how the major political parties in the United States select candidates for elective office, in particular through primary elections. The author reviews various mechanisms of candidate selection, explains the importance of the sequencing, and discusses the pros and cons of primaries, including media coverage, fundraising, party strengthening and candidate preparation. Finally, the article looks at the relevance and potential for US-style primaries for European-level parties in the European Union as a means to increase public engagement in and awareness of future European Parliament elections.
How to Win in Modern Electoral Campaigning
Authors: Strohmeier Gerd
Published: July 2013

The article contributes a macro-political perspective to some questions dealing with voting behaviour in modern democracies, the patterns of an ideal electoral campaign, the factors which are able to decide an election, and the ‘dos’ and ‘don'ts’ in electoral campaigning. It (1) draws up a typology of voters based on party affiliation and rationality; (2) discusses the requirements of electoral campaigns which differ with the political system, the type of political party, the present position of the party or the candidate in the political system and current topics; (3) addresses the impact of the different elements of the ‘political product'–-the party, the programme and the candidates–-and the audiences of the different communication channels in an electoral campaign and (4) approaches how modern electoral campaigns deal with the electorate and the political opponents.
European Elections 2014: What Kind of Dish Will the Parties Serve the Electorate? Will it have a National or European Flavour?
Authors: Peglis Michalis
Published: July 2013

European elections via popular vote were introduced in the 1970s to boost popular interest and European integration. However, at the first election in 1979, people voted without consideration for European issues, but instead with the national agenda in mind. This situation has been repeated on all seven occasions, up to the most recent election in 2009. As we head towards the next European elections in 2014 we explore the differences from previous elections and note the financial crisis in the eurozone, the profound politicisation of the EU and the anticipated implementation of the latest treaty, named after the Lisbon summit. In this overall environment we attempt to assess the type of message that political parties on the national level will present to the electorate. Under certain conditions, we will contend, the next European elections may depart from those studied in previous research analyses.
What Are Structural Reforms?
Authors: Macaes Bruno
Published: July 2013

Policymakers are faced with a crucial choice between ameliorating the symptoms of existing economic problems and trying to address the causes of these problems. The latter goal is what explains the emergence and growing popularity of a relatively new idea: structural reform. What are structural reforms and what challenges do they face? We must start by understanding what the idea implies. First, it calls for a new approach, a general vision of the economy as an integrated system, where policy complementarities abound. Second, it expresses a certain understanding of the relationship between state and market, whereby the state has a foundational or institutional role but does not interfere with economic activity and economic agents. Third, structural reform is in many respects at odds with elements of our political systems, which face increasing challenges when fundamental economic change becomes necessary.
Digital Democracy in the Eu
Authors: Timonen Antti
Published: July 2013

This article discusses digital democracy with particular reference to the political context of the EU. The reasons for adopting tools for digital democracy include fostering closer contact with citizens, sharing ideas, improving the delivery of one's message, crowdsourcing and facilitating digital direct democracy. Twitter has become the medium of choice for Brussels influencers. This is especially so for journalists, whose role has changed in recent years; politicians seem to be following suit. Politicians and political organisations that are actively involved in digital democracy gain the trust of the citizenry if they are approachable and open to discussion and if their online presence reflects their real-life existence.
Gray matter atrophy pattern in elderly with subjective memory impairment
Authors: Peter Jessica , Scheef Lukas , Abdulkadir Ahmed , Boecker Henning , Heneka Michael , Wagner Michael , Koppara Alexander , Klöppel Stefan , Jessen Frank ,   Alzheimer's Disease Neuroimaging Initiative
Published: July 2013

Background

Individuals with subjective memory impairment (SMI) report worsening of memory without impairment in cognitive tests. Despite normal cognitive performance, they may be at higher risk of cognitive decline compared with individuals without SMI.

Methods

We used a discriminative function (a support vector machine) trained on an independent data set of 226 healthy control subjects and 191 patients with probable Alzheimer's disease (AD) dementia to characterize the baseline gray matter patterns of 24 individuals with SMI and 53 control subjects. We tested for associations of these gray matter patterns with SMI presence, cognitive performance at baseline, and cognitive decline at follow‐up.

Results

Individuals with SMI showed greater similarity to an AD gray matter pattern compared with control subjects without SMI. In addition, episodic memory decline was associated with an AD gray matter pattern in the SMI group.

Conclusions

Our results indicate a link between the gray matter atrophy pattern of patients with AD and the presence of SMI. Furthermore, multivariate pattern recognition approaches seem to be a sensitive method for identifying subtle brain changes that correspond to future memory decline in SMI.
Three-dimensional exact coherent states in rotating channel flow
Authors: Wall D. P. , Nagata M.
Published: July 2013

Three-dimensional exact, finite-amplitude solutions are presented for the problem of channel flow subject to a system rotation about a spanwise axis. The solutions are of travelling wave form, and may bifurcate as tertiary flows from the two-dimensional streamwise-independent secondary flow, or as secondary flows directly from the basic flow. For the tertiary flows, we consider solutions of spanwise superharmonic and subharmonic type. We distinguish flows on the basis of symmetry, originating eigenmode and major solution branch, and thus identify 15 distinct flows: 5 superharmonic tertiary, 5 subharmonic tertiary and 5 secondary flows. The tertiary flows all feature a single layer of vortical structures in the spanwise–wall-normal plane, the secondary flows feature single-, double-, triple- or quadruple-layer flow structures in this plane. All flows feature low-speed streamwise-orientated streaks in the streamwise velocity component and/or pulses of low-speed streamwise velocity. The streaks may be sinusoidal or varicose. Sinusoidal streaks are flanked by staggered streamwise vortices, varicose streaks and pulses are flanked by aligned vortices. A comparison with previous simulation and experimental studies finds that the simplest three-dimensional flows observed previously correspond to superharmonic tertiary flows bifurcating from the upper branch of the secondary flow. The mean absolute vorticity of the present flows is also considered. A flattening of the profile of this vorticity is observed in the central region of the channel for two-dimensional secondary and many of the three-dimensional flows, with two-step profiles also observed. This phenomenon is attributed to mixing of the vorticity across zones of the channel in which streamwise vortex structures exist, and is demonstrated by a two-dimensional model. The phenomenon appears to be distinct to that observed in fully turbulent rotating channel flows.
Logarithmic scaling of turbulence in smooth- and rough-wall pipe flow
Authors: Hultmark M. , Vallikivi M. , Bailey S. C. C. , Smits A. J.
Published: July 2013

Measurements of the streamwise component of the turbulent fluctuations in fully developed smooth and rough pipe flow are presented over an unprecedented Reynolds number range. For Reynolds numbers$R{e}_{\tau } \gt 20\hspace{0.167em} 000$, the streamwise Reynolds stress closely follows the scaling of the mean velocity profile, independent of the roughness, and over the same spatial extent. This observation extends the findings of a logarithmic law in the turbulence fluctuations as reported by Hultmark, Vallikivi & Smits (Phys. Rev. Lett., vol. 108, 2012) to include rough flows. The onset of the logarithmic region is found at a location where the wall distance is equal to ∼100 times the Kolmogorov length scale, which then marks sufficient scale separation for inertial scaling. Furthermore, in the logarithmic region the square root of the fourth-order moment also displays logarithmic behaviour, in accordance with the observation that the underlying probability density function is close to Gaussian in this region.
Optimal perturbations of gravitationally unstable, transient boundary layers in porous media
Authors: Daniel Don , Tilton Nils , Riaz Amir
Published: July 2013

We study the linear stability of gravitationally unstable, transient, diffusive boundary layers in porous media using non-modal stability theory. We first perform a classical optimization procedure, using an adjoint-based method, to obtain the perturbations at the initial time $t= {t}_{p} $ that have a maximum amplification at a final time $t= {t}_{f} $. We then investigate the sensitivity of the optimal perturbations to the initial time, ${t}_{p} $, and the final time, ${t}_{f} $, as well as different measures of perturbation amplification. Due to the transient nature of the base state, we demonstrate that there is an optimal initial perturbation time, ${ t}_{p}^{o} $. By rescaling the problem, we develop analytical relationships for the optimal initial time and wavenumber in terms of aquifer properties. We also demonstrate that the classical optimization procedure essentially recovers the dominant perturbation structures predicted by a quasi-steady modal analysis. Although the classical optimal perturbations are mathematically valid, we observe that due to physical constraints, they are unlikely to reflect analogous laboratory experiments. Therefore, we propose a modified optimization procedure (MOP) that constrains the optimization to physically admissible initial perturbation fields. We compare the results of the classical and modified optimization procedures with quasi-steady modal analyses and initial value problems commonly used in the literature. Finally, we validate the predictions of the modified optimization scheme by performing direct numerical simulations (DNS) that emulate the onset of convection in physical systems.
La symphonie de l'être dans le Sophiste de Platon
Authors: Mattéi Jean-François
Published: July 2013

Un monde nouveau apparaît avec la dialectique platonicienne, qui brise l'harmonie native de la pensée archaïque et sa rayonnante unité, pour opposer désormais le royaume invisible des Formes dont lâme conserve, en une tonalité mineure, la nostalgie, et le troublant exil des corps, livrés aux désirs ehatoyants des simulacres. Issue d'une disso-nance aussi radicale, la philosophie s'épuisera au cours de son histoire à tenter de combler le χωρισμóς pour se résoudre en un accord parfait. Cette interprétation communément reçue du platonisme, qui prédispose à l'idéalisme comme au christianisme, commande encore les lectures critiques de Nietzsche et de Heidegger, mais tient déjà tout entière dans la fresque de Raphaël: représenté près d'Aristote dont la main, largement ouverte, impose sa maîtrise à la terre, l'auteur du Timée montre, d'un doigt impératif, la direction du ciel.
Recovery: an international perspective
Authors: Slade Mike , Amering Michaela , Oades Lindsay
Published: July 2013

Aims– To review developments in recovery-focussed mental health services internationally.Methods– Two forms of ‘recovery’ which have been used in the literature are considered, and international examples of recovery-focussed initiatives reviews. A ‘litmus test’ for a recovery-focussed service is proposed.Results– ‘Clinical recovery’ has emerged from professional literature, focuses on sustained remission and restoration of functioning, is invariant across individuals, and has been used to establish rates of recovery. ‘Personal recovery’ has emerged from consumer narratives, focuses on living a satisfying, hopeful and contributing life even with limitations caused by the illness, varies across individuals, and the empirical evidence base relates to stages of change more than overall prevalence rates. Clinical and personal recovery are different. Two innovative, generalisable and empirically investigated examples are given of implementing a focus on personal recovery: the Collaborative Recovery Model in Australia, and Trialogues in German-speaking Europe. The role of medication is an indicator: services in which all service users are prescribed medication, in which the term ‘compliance’ is used, in which the reasoning bias is present of attributing improvement to medication and deterioration to the person, and in which contact with and discussion about the service user revolves around medication issues, are not personal recovery-focussed services.Conclusions– The term ‘Recovery’ has been used in different ways, so conceptual clarity is important. Developing a focus on personal recovery is more than a cosmetic change – it will entail fundamental shifts in the values of mental health services.

Declaration of Interest: None.
Spt6 prevents transcription-coupled loss of posttranslationally modified histone H3
Authors: Kato Hiroaki , Okazaki Kosuke , Iida Tetsushi , Nakayama Jun-ichi , Murakami Yota , Urano Takeshi
Published: July 2013

The tail of histone H3 is an ideal medium for storing epigenetic information because displacement of histone H3 is heavily restricted during transcription. To maintain the locus-specific modifications of histone H3, histone molecules should be retained locally at the original position through multiple rounds of transcription. Here, we found that fission yeast Spt6, a highly conserved RNA polymerase II-interacting histone H3–H4 chaperone, is essential for the maintenance of Lys-4 and Lys-9 methylation of histone H3 in euchromatin and heterochromatin, respectively. In euchromatin, loss of Lys-4 methylated histone H3 and deposition of newly synthesized Lys-56 acetylated histone H3 induced by Spt6 inactivation were coupled with transcription. While in heterochromatin, Spt6 prevents histone turnover and cryptic transcription in parallel with Clr3 histone deacetylase. We propose that Spt6 retains posttranslationally modified histone H3 during transcription to maintain epigenome integrity.
Preserving user‐participation for insecure network communications with CAPTCHA and visual secret sharing technique
Authors: Lee Jung‐San , Hsieh Ming‐Huang
Published: July 2013

How to provide confidential communications for involved users is always a critical challenge in designing a network system. Especially, people must face malicious attacks while surfing over an insecure network, such as brute force attack, password guessing attack, DOS attack, masquerade attack, replay attack or Trojan horse risk. Let these attacks be surveyed in more detail, and the authors can find the fact that the intruder usually launches these through thousands of trials without the interaction between the user and server. Of course, these trials are performed via bots. Thus, this study aims to develop a robust system that can guarantee the user‐participation essential in the communication. That is, if the involved participants cannot prove that they are human beings, then the system will terminate the connection to prevent the attack. To achieve this, the authors apply the techniques of CAPTCHA and visual secret sharing into this system. Aside from proving the correctness of the authentication between the involved participants, the authors have conducted experiments to demonstrate the practicability of the proposed system.
Analysis of directional neighbour discovery process in millimetre wave wireless personal area networks
Authors: Kim Meejoung , Kim Yong Sang , Lee Wooyong
Published: July 2013

The millimetre wave (mmWave) band offers the potential for multi‐gigabit indoor wireless personal area networks (WPANs). However, it has problems such as a short wavelength. To compensate, utilisation of directional antennas at the physical layer is recommended. For communications using this band, neighbour discovery using directional antennas (D‐ND) is one of the crucial steps. In this study, the D‐ND process is analysed mathematically for mmWave WPANs based on the concept of an exclusive region, and the values that are derived from the effect of using directional antennas. Maximising the neighbour discovery probability for a given amount of time is considered as an objective function. Performance measures are derived in closed forms, such as the probability of discovering a device for one self‐advertising packet and the power‐efficient sojourn time of a device in one direction. Numerical results are obtained using parameters based on the IEEE 802.15.3c standard. The results show that the efficiency of the D‐ND depends not only on how often devices transmit a self‐advertising packet, but also on antenna properties such as beamwidth. The mathematical analysis provides a theoretical basis for the D‐ND process, and the obtained results illustrate the physical layer impact on neighbour discovery.
Mitigating shadowing effects through cluster‐head cooperation techniques
Authors: Bithas Petros S. , Lioumpas Athanasios S. , Alexiou Angeliki
Published: July 2013

In many situations the performance of wireless communication systems decreases especially when they operate over multipath fading channels subject also to shadowing. In this sense, cluster‐based networks have been introduced as an efficient solution, offering coverage extension and energy saving. In this study, the authors investigate new cluster‐head (CH) selection algorithms, where the nodes can select different CHs, according to the corresponding signal strength. In addition, it is shown that if CHs are equipped with multiple antennas, the negative consequences of fading/shadowing can be further reduced. The performance of this scheme is theoretically investigated over correlated Nakagami‐m fading channels, which are also subject to shadow fading, modelled by gamma distribution. The derived statistical metrics are used to obtain numerical evaluated results for the outage and the average bit error probabilities. These results are complemented by computer simulated ones, which validate the accuracy of the proposed analysis.
Temperature field reconstruction from the partial measurement data using the gappy proper orthogonal decomposition
Authors: Lei Jing , Liu Shi
Published: July 2013

Fast reconstruction of the temperature field from the partial temperature measurement data is highly desirable in the field of thermal engineering, in which reconstruction algorithms play a crucial role in real applications. Based on the gappy proper orthogonal decomposition technique, a promising approach that integrates the numerical simulation information and the measurement information is proposed in this study for the temperature field reconstruction from the partial measurement data, where the original reconstruction problem is formulated into an optimisation problem. An objective functional, which simultaneously considers the outliers in the measurement data and the model approximation distortions, is presented. Based on the split Bregman iteration technique, an iterative scheme is developed for solving the proposed objective functional. Numerical simulations are implemented to demonstrate the feasibility and effectiveness of the proposed algorithm.
SPICE circuit model of voltage excitation fluxgate sensor
Authors: Yang Shanglin , Liu Shibin , Feng Wenguang , Guo Bo , Hou Xiaowei , Li Juping
Published: July 2013

A simulation program with integrated circuit emphasis (SPICE) circuit model of voltage excitation fluxgate was proposed. It used the arctangent function to describe the hysteresis loop of fluxgate core, the excitation and measurement coils of the fluxgate were equivalent to a circuit model that contains a kind of non‐linear time‐varying inductance. Moreover, the expression of non‐linear time‐varying inductance has been given, which resolved fluxgate modelling itself into solving non‐homogeneous ordinary differential equations with variable coefficient, and then the authors used HSPICE to solve the differential equations. The input and output characteristics of the dual‐core fluxgate were simulated by this SPICE model. The results show that the model can better simulate the input and output characteristics of actual fluxgate, which verifies the validity of the model.
Electronic structure differences between H2-, Fe-, Co-, and Cu-phthalocyanine highly oriented thin films observed using NEXAFS spectroscopy
Authors: Willey T. M. , Bagge-Hansen M. , Lee J. R. I. , Call R. , Landt L. , van Buuren T. , Colesniuc C. , Monton C. , Valmianski I. , Schuller Ivan K.
Published: July 2013

Phthalocyanines, a class of macrocyclic, square planar molecules, are extensively studied as semiconductor materials for chemical sensors, dye-sensitized solar cells, and other applications. In this study, we use angular dependent near-edge x-ray absorption fine structure (NEXAFS) spectroscopy as a quantitative probe of the orientation and electronic structure of H2-, Fe-, Co-, and Cu-phthalocyanine molecular thin films. NEXAFS measurements at both the carbon and nitrogen K-edges reveal that phthalocyanine films deposited on sapphire have upright molecular orientations, while films up to 50 nm thick deposited on gold substrates contain prostrate molecules. Although great similarity is observed in the carbon and nitrogen K-edge NEXAFS spectra recorded for the films composed of prostrate molecules, the H2-phthalocyanine exhibits the cleanest angular dependence due to its purely out-of-plane π* resonances at the absorption onset. In contrast, organometallic-phthalocyanine nitrogen K-edges have a small in-plane resonance superimposed on this π* region that is due to a transition into molecular orbitals interacting with the 3dx2-y2 empty state. NEXAFS spectra recorded at the metal L-edges for the prostrate films reveal dramatic variations in the angular dependence of specific resonances for the Cu-phthalocyanines compared with the Fe-, and Co-phthalocyanines. The Cu L3,2 edge exhibits a strong in-plane resonance, attributed to its b1g empty state with dx2-y2 character at the Cu center. Conversely, the Fe- and Co- phthalocyanine L3,2 edges have strong out-of-plane resonances; these are attributed to transitions into not only b1g (dz2) but also eg states with dxz and dyz character at the metal center.
Reduced explicitly correlated Hartree-Fock approach within the nuclear-electronic orbital framework: Theoretical formulation
Authors: Sirjoosingh Andrew , Pak Michael V. , Swalina Chet , Hammes-Schiffer Sharon
Published: July 2013

The nuclear-electronic orbital (NEO) method treats electrons and select nuclei quantum mechanically on the same level to extend beyond the Born-Oppenheimer approximation. Electron-nucleus dynamical correlation has been found to be highly significant due to the attractive Coulomb interaction. The explicitly correlated Hartree-Fock (NEO-XCHF) approach includes explicit electron-nucleus correlation with Gaussian-type geminal functions during the variational optimization of the nuclear-electronic wavefunction. Although accurate for small model systems, the NEO-XCHF method is computationally impractical for larger chemical systems. In this paper, we develop the reduced explicitly correlated Hartree-Fock approach, denoted NEO-RXCHF, where only select electronic orbitals are explicitly correlated to the nuclear orbitals. By explicitly correlating only the relevant electronic orbitals to the nuclear orbitals, the NEO-RXCHF approach avoids problems that can arise when all electronic orbitals are explicitly correlated to the nuclear orbitals in the same manner. We examine three different NEO-RXCHF methods that differ in the treatment of the exchange between the geminal-coupled electronic orbitals and the other electronic orbitals: NEO-RXCHF-fe is fully antisymmetric with respect to exchange of all electronic coordinates and includes all electronic exchange terms; NEO-RXCHF-ne neglects the exchange between the geminal-coupled electronic orbitals and the other electronic orbitals; and NEO-RXCHF-ae includes approximate exchange terms between the geminal-coupled electronic orbitals and the other electronic orbitals. The latter two NEO-RXCHF methods offer substantial computational savings over the NEO-XCHF approach. The NEO-RXCHF approach is applicable to a wide range of chemical systems that exhibit non-Born-Oppenheimer effects between electrons and nuclei, as well as positron-containing molecular systems.
Linear thermal expansion coefficient determination using in situ curvature and temperature dependent X-ray diffraction measurements applied to metalorganic vapor phase epitaxy-grown AlGaAs
Authors: Maaßdorf A. , Zeimer U. , Grenzer J. , Weyers M.
Published: July 2013

Al x Ga 1 − x As grown on GaAs is known to be almost perfectly lattice matched with a maximum lattice mismatch of 0.14% at room temperature and even less at temperatures of 700 °C–800 °C. However, as layer structures for edge-emitting diode lasers exhibit an increasing overall thickness of several microns of AlxGa1−xAs, e.g., diode lasers comprising a super-large optical cavity, the accumulated elastic strain energy increases as well. Depending on the growth temperature the formation energy of dislocations can be reached, which is limiting the pseudomorphic growth. In this regard, the thermal expansion coefficient difference between layer and substrate is an important parameter. We utilize in situ curvature measurements during growth of AlxGa1−xAs by metal-organic vapour phase epitaxy to determine the thermal expansion coefficient α. The curvature change with increasing layer thickness, as well as with wafer temperature at constant layer thickness is used to assess α. This is compared to ex situ temperature dependent X-ray diffraction measurements to obtain α. All determined values for α are in good agreement, yielding αAlAs=4.1×10−6 K−1 for a given GaAs linear thermal expansion coefficient of αGaAs=5.73×10−6 K−1.
The X+ 2Πg, A+ 2Πu, B+ 2Δu, and $\mathrm{a}^+\ ^4\Sigma _{\mathrm{u}}^-$a+Σu−4 electronic states of ${\rm Cl}_2^+$ Cl 2+ studied by high-resolution photoelectron spectroscopy
Authors: Mollet Sandro , Merkt Frédéric
Published: July 2013

Partially rotationally resolved pulsed-field-ionization zero-kinetic-energy photoelectron spectra of the three isotopomers (35Cl2, 35Cl37Cl, and 37Cl2) of Cl2 have been recorded in the wavenumber ranges 92 500–96 500 cm−1, corresponding to transitions to the low vibrational levels of the X+ 2Πg (Ω = 3/2, 1/2) ground state of ${\rm Cl}_2^+$ Cl 2+, and 106 750–115 500 cm−1, where the $\mathrm{a}^+\ ^4\Sigma _\mathrm{u}^-\break \leftarrow \mathrm{X}\ ^1\Sigma _\mathrm{g}^+$a+Σu−4←XΣg+1, $\mathrm{A}^+\ ^2\Pi _\mathrm{u}\leftarrow \mathrm{X}\ ^1\Sigma _\mathrm{g}^+$A+Πu2←XΣg+1, and $\mathrm{B}^+\ ^2\Delta _\mathrm{u}\leftarrow \mathrm{X}\ ^1\Sigma _\mathrm{g}^+$B+Δu2←XΣg+1 band systems overlap with transitions to high vibrational levels (v+ > 25) of the X+ state. The observation of Franck-Condon-forbidden transitions to vibrational levels of the X+ state of the cation with v+ ⩾ 25 is rationalized by a mechanism involving vertical excitation of predissociative Rydberg states of mixed singlet-triplet character with an A+ ion core which are coupled to Rydberg states converging to high-v+ levels of the X+ state. The same mechanism is proposed to also be responsible for the observation of Cl+ − Cl− ion pairs and quartet states in the photoionization of Cl2. The potential energy function of the X+ state of ${\rm Cl}_2^+$ Cl 2+ was determined in a direct fit to the experimental data. Transitions to vibrational levels of the A+ 2Πu, 3/2 and B+ 2Δu, 3/2 states of ${\rm Cl}_2^+$ Cl 2+ could be identified using the results of a recent analysis of the strong perturbation between the A+ 2Πu, 3/2 and B+ 2Δu, 3/2 states of ${\rm Cl}_2^+$ Cl 2+ observed in the A+ − X+ band system [Gharaibeh et al., J. Chem. Phys. 137, 194317 (2012)]10.1063/1.4765334, and transitions to several vibrational levels of the upper spin-orbit component (2Πu, 1/2) of the A+ state were detected in the photoelectron spectrum of ${\rm Cl}_2^+$ Cl 2+. The $\mathrm{a}^+\ ^4\Sigma _\mathrm{u}^-\leftarrow \mathrm{X}\ ^1\Sigma _\mathrm{g}^+$a+Σu−4←XΣg+1 photoelectron band system, which is nominally forbidden by single-photon ionization from the ground state was also observed for the first time and its vibrational and spin-orbit structures were analyzed. The $^4\Sigma _\mathrm{u}^-$Σu−4 state is split into two spin-orbit components with Ω = 1/2 and Ω = 3/2, separated by 37.5 cm−1. The vibrational energy level structure of both components is regular, which indicates that the splitting results from the interaction with one or more distant ungerade Ω = 1/2 or Ω = 3/2 electronic states.
A novel extreme ultraviolet four channels normal incidence imaging system for plasma diagnostics of Z-pinch facility
Authors: Wang Xin , Mu Baozhong , Zhu Jingtao , Wang Ling , Yi Shengzhen , Li Wenbin , Wang Zhanshan , Qin Yi , Xu Zeping , Xu Rongkun , Li Zhenghong
Published: July 2013

A novel EUV four channels normal incidence imaging system for plasma diagnostics of Z-pinch facility was presented in this paper, which consists of four concave mirrors and one convex mirror used for focusing an object onto four different positions with about 30 μm resolution on the same image plane. In addition, this imaging system can work at the energies of 50 eV, 95 eV, 150 eV, and broadband of 50–100 eV by using different multilayer films deposited on the concave and convex mirrors. This instrument, combined with framing camera, can achieve the power of two-dimensional spatial and temporal resolution, as well as the ability to imaging the plasma at the specific temperature. In the paper, the four channels microscope centering at multi-energies was developed.
Exactly solvable chaos in an electromechanical oscillator
Authors: Owens Benjamin A. M. , Stahl Mark T. , Corron Ned J. , Blakely Jonathan N. , Illing Lucas
Published: July 2013

A novel electromechanical chaotic oscillator is described that admits an exact analytic solution. The oscillator is a hybrid dynamical system with governing equations that include a linear second order ordinary differential equation with negative damping and a discrete switching condition that controls the oscillatory fixed point. The system produces provably chaotic oscillations with a topological structure similar to either the Lorenz butterfly or Rössler's folded-band oscillator depending on the configuration. Exact solutions are written as a linear convolution of a fixed basis pulse and a sequence of discrete symbols. We find close agreement between the exact analytical solutions and the physical oscillations. Waveform return maps for both configurations show equivalence to either a shift map or tent map, proving the chaotic nature of the oscillations.
Alfvén wave collisions, the fundamental building block of plasma turbulence. I. Asymptotic solution
Authors: Howes G. G. , Nielson K. D.
Published: July 2013

The nonlinear interaction between counterpropagating Alfvén waves is the physical mechanism underlying the cascade of energy to small scales in astrophysical plasma turbulence. Beginning with the equations for incompressible MHD, an asymptotic analytical solution for the nonlinear evolution of these Alfvén wave collisions is derived in the weakly nonlinear limit. The resulting qualitative picture of nonlinear energy transfer due to this mechanism involves two steps: first, the primary counterpropagating Alfvén waves interact to generate an inherently nonlinear, purely magnetic secondary fluctuation with no parallel variation; second, the two primary waves each interact with this secondary fluctuation to transfer energy secularly to two tertiary Alfvén waves. These tertiary modes are linear Alfvén waves with the same parallel wavenumber as the primary waves, indicating the lack of a parallel cascade. The amplitude of these tertiary modes increases linearly with time due to the coherent nature of the resonant four-wave interaction responsible for the nonlinear energy transfer. The implications of this analytical solution for turbulence in astrophysical plasmas are discussed. The solution presented here provides valuable intuition about the nonlinear interactions underlying magnetized plasma turbulence, in support of an experimental program to verify in the laboratory the nature of this fundamental building block of astrophysical plasma turbulence.
Structure and thermoelectric properties of EuTi(O,N)3 ± δ
Authors: Sagarna L. , Rushchanskii K. Z. , Maegli A. , Yoon S. , Populoh S. , Shkabko A. , Pokrant S. , Ležaić M. , Waser R. , Weidenkaff A.
Published: July 2013

After partial substitution of nitrogen for oxygen in EuTiO3, the crystal structure, thermoelectric properties, morphology, and electronic structure of the products were analyzed and compared with pristine EuTiO3. The space group of EuTi(O,N)3 ± δ was orthorhombic Pnma due to the tilt and rotation of the anion octahedra, compared to cubic Pm3¯m of EuTiO3 (at room temperature). The thermoelectric properties of oxynitride polycrystalline bodies sintered in three different ways were investigated in the temperature range of 300 K < T < 950 K. The Seebeck coefficients (S) of the oxynitrides were lower compared with the oxide, and the electrical resistivities (ρ) were increased about one order of magnitude. The activation energies (EA) indicated a larger band gap of EuTi(O,N)3 ± δ when compared to the pristine EuTiO3 (∼1.3 eV compared to 0.98 eV). A morphological characterization by transmission electron microscopy and scanning electron microscopy illustrated intrinsic nanopores within the individual particles and weak grain-interconnections indicating poor intergrain electron transport. Ab initio calculations of the electronic structures confirmed a larger band gap of the distorted crystal structure of the oxynitride and showed a decrease of the density of states at the Fermi level, explaining the reduction of the measured S.
Modeling combined coherent and incoherent scattering structures for light trapping in solar cells
Authors: Abass Aimi , Trompoukis Christos , Leyre Sven , Burgelman Marc , Maes Bjorn
Published: July 2013

Current structures for solar cells or LEDs often incorporate layers of various optical regimes, with a mixture of coherent, partially coherent or incoherent behavior. We developed a simple and efficient calculation method to study such combined solar cell structures with both wave and ray optics sections. These One-Pass Coherent calculations take wave effects into account where they matter the most, while avoiding a large computational domain to model rough structures. The method simulates a general diffuser by working directly with the reflected wavefronts, instead of using its geometry. We utilize this method to study thin film silicon solar cell structures with a grating on the front and a diffuser at the back. More absorption is obtained with the combined light trapping scheme of appropriate characteristics, compared with grating-only or diffuser-only counterparts. Finally, we report a significant effect of incoherence on the absorption of fairly thin (∼10 μm) cells. We demonstrate that partially incoherent light can be more efficiently absorbed than fully coherent light on average over a broad wavelength range. It turns out that the scarcity of guided modes for fully coherent light can hinder the grating enhancement, leading to a consistently better performance when light coherence is limited or lost.
Thermally assisted manipulation of magnetic domain structures in amorphous rare-earth-Fe-B film
Authors: Gao J. L. , Zhang S. Y. , Luo X. J. , Xia W. B. , Li Y. L. , Tang S. L. , Du Y. W.
Published: July 2013

The temperature dependence of domain evolution in amorphous rare-earth-Fe-B film is investigated via magnetic force microscopy as well as magnetization measurements. Within an external 1.0 kOe magnetic field perpendicular to the film, the domains evolve from stripes to bubbles as the temperature increases. Both of the domain wall motion and domain nucleation processes are found to be independent of the film defects. It leads to the formation of nearly perfect bubble domains with their sizes exhibiting a Gaussian distribution. If the external field is removed, the magnetic field generated by the scanning tip has to be taken into consideration. It is found that the tip field, although weak and localized, can modify the local domain structure within the scan area at 373 K. To explain the experimental results, we propose that the domain structure is usually stuck in one of the metastable states separated by energy barriers at a given temperature. The switching between different states is commonly governed by energy barriers and thermal activation, which could be partly controlled by the magnetic field and the temperature, respectively.
Drop motion, deformation, and cyclic motion in a non-uniform electric field in the viscous limit
Authors: Mhatre Sameer , Thaokar Rochish M.
Published: July 2013

Drop motion and deformation of a conducting drop in a perfect (or leaky) dielectric fluid and a leaky dielectric drop in a leaky dielectric fluid, in a non-uniform electric field is presented. The investigated non-uniform electrode configuration is of the pin-plate type. Systematic experiments and comparison with existing analytical models is carried out. The main results are summarized as follows: (i) The dielectrophoretic motion of a conducting drop in a non-uniform electric field is explained reasonably well assuming a spherical drop, although deviations are observed at large deformations. Thus dielectrophoretic motion shows a weak shape dependence. (ii) The deformation of a conducting drop in a non-uniform electric field has comparable contributions from the uniform and the non-uniform components of the applied field. (iii) The leaky dielectric nature of the medium results in three different states for a conducting drop (a) no movement, (b) near electrode cyclic motion, and (c) cyclic motion between the electrodes. The frequency of cyclic motion decreases with electric field for near electrode motion. On the contrary it increases with the applied field for electrode-electrode cyclic motion. The leaky dielectric system showing positive dielectrophoresis leads to the drop getting attached to the pin electrode causing emulsification at large field. A leaky dielectric drop suspended in a dielectric, system exhibiting negative dielectrophoresis shows oblate deformation which is augmented by the plate-drop hydrodynamic interaction.
Temperature of critical clusters in nucleation theory: Generalized Gibbs' approach
Authors: Schmelzer Jürn W. P. , Boltachev Grey Sh. , Abyzov Alexander S.
Published: July 2013

According to the classical Gibbs' approach to the description of thermodynamically heterogeneous systems, the temperature of the critical clusters in nucleation is the same as the temperature of the ambient phase, i.e., with respect to temperature the conventional macroscopic equilibrium conditions are assumed to be fulfilled. In contrast, the generalized Gibbs' approach [J. W. P. Schmelzer, G. Sh. Boltachev, and V. G. Baidakov, J. Chem. Phys. 119, 6166 (2003)10.1063/1.1602066; J. W. P. Schmelzer, G. Sh. Boltachev, and V. G. Baidakov, J. Chem. Phys. 124, 194503 (2006)]10.1063/1.2196412 predicts that critical clusters (having commonly spatial dimensions in the nanometer range) have, as a rule, a different temperature as compared with the ambient phase. The existence of a curved interface may lead, consequently, to an equilibrium coexistence of different phases with different temperatures similar to differences in pressure as expressed by the well-known Laplace equation. Employing the generalized Gibbs' approach, it is demonstrated that, for the case of formation of droplets in a one-component vapor, the temperature of the critical droplets can be shown to be higher as compared to the vapor. In this way, temperature differences between critically sized droplets and ambient vapor phase, observed in recent molecular dynamics simulations of argon condensation by Wedekind et al. [J. Chem. Phys. 127, 064501 (2007)]10.1063/1.2752154, can be given a straightforward theoretical interpretation. It is shown as well that – employing the same model assumptions concerning bulk and interfacial properties of the system under consideration – the temperature of critical bubbles in boiling is lower as compared to the bulk liquid.
Alfvén wave collisions, the fundamental building block of plasma turbulence. IV. Laboratory experiment
Authors: Drake D. J. , Schroeder J. W. R. , Howes G. G. , Kletzing C. A. , Skiff F. , Carter T. A. , Auerbach D. W.
Published: July 2013

Turbulence is a phenomenon found throughout space and astrophysical plasmas. It plays an important role in solar coronal heating, acceleration of the solar wind, and heating of the interstellar medium. Turbulence in these regimes is dominated by Alfvén waves. Most turbulence theories have been established using ideal plasma models, such as incompressible MHD. However, there has been no experimental evidence to support the use of such models for weakly to moderately collisional plasmas which are relevant to various space and astrophysical plasma environments. We present the first experiment to measure the nonlinear interaction between two counterpropagating Alfvén waves, which is the building block for astrophysical turbulence theories. We present here four distinct tests that demonstrate conclusively that we have indeed measured the daughter Alfvén wave generated nonlinearly by a collision between counterpropagating Alfvén waves.
Kinetic equilibrium of space charge dominated beams in a misaligned quadrupole focusing channel
Authors: Goswami A. , Sing Babu P. , Pandit V. S.
Published: July 2013

The dynamics of intense beam propagation through the misaligned quadrupole focusing channel has been studied in a self-consistent manner using nonlinear Vlasov-Maxwell equations. The equations of motion of the beam centroid have been developed and found to be independent of any specific beam distribution. A Vlasov equilibrium distribution and beam envelope equations have been obtained, which provide us a theoretical tool to investigate the dynamics of intense beam propagating in a misaligned quadrupole focusing channel. It is shown that the displaced quadrupoles only cause the centroid of the beam to wander off axis. The beam envelope around the centroid obeys the familiar Kapchinskij-Vladimirskij envelope equation that is independent of the centroid motion. However, the rotation of the quadrupole about its optical axis affects the beam envelope and causes an increase in the projected emittances in the two transverse planes due to the inter-plane coupling.
Direct silicon bonding dynamics: A coupled fluid/structure analysis
Authors: Navarro E. , Bréchet Y. , Moreau R. , Pardoen T. , Raskin J.-P. , Barthelemy A. , Radu I.
Published: July 2013

During direct bonding, a thin gas film is trapped in-between the two wafers, leading to an interactive fluid/structure dynamics. A model of bonding dynamics is formulated using the plate approximation, Reynolds equation, and adhesion forces as the boundary condition at the bonding front. The transient equation is solved numerically in a one dimensional cylindrical case. The entire process, including initiation and propagation of the front, is modelled. The model is supported by experimental data from an original setup involving non-contact optical sensors to measure the vertical movement of the wafer during the bonding sequence.
Microplasma source for optogalvanic spectroscopy of nanogram samples
Authors: Berglund M. , Thornell G. , Persson A.
Published: July 2013

The demand for analysis of smaller samples in isotopic ratio measurements of rare isotopes is continuously rising with the development of new applications, particularly in biomedicine. Interesting in this aspect are methods based on optogalvanic spectroscopy, which have been reported to facilitate both 13C-to-12C and 14C-to-12C ratio measurements with high sensitivity. These methods also facilitate analysis of very small samples, down to the microgram range, which makes them very competitive to other technologies, e.g., accelerator mass spectroscopy. However, there exists a demand for moving beyond the microgram range, especially from regenerative medicine, where samples consist of, e.g., DNA, and, hence, the total sample amount is extremely small. Making optogalvanic spectroscopy of carbon isotopes applicable to such small samples, requires miniaturization of the key component of the system, namely the plasma source, in which the sample is ionized before analysis. In this paper, a novel design of such a microplasma source based on a stripline split-ring resonator is presented and evaluated in a basic optogalvanic spectrometer. The investigations focus on the capability of the plasma source to measure the optogalvanic signal in general, and the effect of different system and device specific parameters on the amplitude and stability of the optogalvanic signal in particular. Different sources of noise and instabilities are identified, and methods of mitigating these issues are discussed. Finally, the ability of the cell to handle analysis of samples down to the nanogram range is investigated, pinpointing the great prospects of stripline split-ring resonators in optogalvanic spectroscopy.
Effect of structural and magnetic exchange coupling on the electronic transport of NdNiO3 films intercalated with La0.7Sr0.3MnO3 thin layers
Authors: Pandey Parul , Rana Rakesh , Tripathi Shivendra , Rana D. S.
Published: July 2013

We have fabricated multilayer structure of half-metallic ferromagnet La0.7Sr0.3MnO3 and insulator-metal transition system NdNiO3 on SrTiO3 (100) substrate; thin layers of the former are intercalated in the major matrix of the later. The two structures exhibit pseudomorphic structural coupling with each other. We show that a large increase in the conductivity and an enhanced irreversibility across insulator-metal transition of NdNiO3 may be realized by varying the thickness of La0.7Sr0.3MnO3 and the ratio of thickness of the two layers. Corroborated by the magnetization data, it is shown that the combined effect of structure and magnetism by interfacial coupling is a much better technique than the chemical modification to control the electrical transport of NdNiO3.
Ferromagnetic sandwich-like wires constructed with transition metals and anthracene
Authors: Wang Xianlong , Zheng Xiaohong , Zeng Zhi
Published: July 2013

Properties of one-dimensional sandwich-like organometallic wires, [TM2(Ant)]∞, constructed with transition metals (TM = Sc, Ti, V, Cr, Mn, and Fe) and anthracene (Ant = C14H10) are systematically investigated by first-principles calculations. Our results show that the properties of [TM2(Ant)]∞ are mainly determined by charge transfer and the magnetic properties in [TM2(Ant)]∞ are much more diverse than those in [TM(Bz)]∞ due to the fact that HOMO-LUMO gap of Ant is much smaller than that of benzene (Bz = C6H6). In particular, [V2(Ant)]∞ and [Cr2(Ant)]∞ are found to be half-metallic ferromagnets, indicating that they are better than [TM(Bz)]∞ for spintronic devices due to high conductivity and stability. Furthermore, because the HOMO-LUMO gap of graphene flakes decreases with increasing size, the charge transfer effect may also manifest in sandwich-like wires based on graphene flakes and TM, which are also proposed to be potential candidates for spin transport.