bluuebunny/crossref_metadata_2025 huggingface dataset:
Internet-Based Acceptance and Commitment Therapy for Psychological Distress Experienced by People With Hearing Problems: Study Protocol for a Randomized Controlled Trial
Authors: Molander Peter , Hesser Hugo , Weineland Sandra , Bergwall Kajsa , Buck Sonia , Hansson-Malmlöf Johan , Lantz Henning , Lunner Thomas , Andersson Gerhard
Published: July 2015

Purpose

Psychological distress and psychiatric symptoms are prevalent among people with hearing loss or other audiological conditions, but psychological interventions for these groups are rare. This article describes the study protocol for a randomized controlled trial for evaluating the effect of a psychological treatment delivered over the Internet for individuals with hearing problems and concurrent psychological distress.

Method

Participants who are significantly distressed will be randomized to either an 8-week Internet-delivered acceptance-based cognitive behavioral therapy (i.e., acceptance and commitment therapy [ACT]), or wait-list control. We aim to include measures of distress associated with hearing difficulties, anxiety, and depression. In addition, we aim to measure acceptance associated with hearing difficulties as well as quality of life.

Conclusion

The results of the trial may further our understanding of how to best treat people who present problems with both psychological distress and hearing in using the Internet.
Implementing Internet-Based Aural Rehabilitation in a General Clinical Practice
Authors: Malmberg Milijana , Lunner Thomas , Kähäri Kim , Jansson Gunilla , Andersson Gerhard
Published: July 2015

Purpose

The purpose of this paper is to share the lessons that were learned about the process of implementing an Internet-based, randomized controlled trial (RCT) in general clinical practice (GCP) and to address some of the advantages of using the Internet as a tool to implement a RCT in GCP. The RCT implemented focused on investigating Internet-based aural rehabilitation (AR) in addition to hearing aid (HA)-fitting supplemented with telephone support, and it was applied in a clinical setting. The results of this RCT and the questionnaires chosen will be presented in an article elsewhere.

Procedure

Here, the procedure of the implemented trial is presented, and the implementation challenges are presented and discussed. Specifically, we describe the trial
research question
,
recruitment
strategy, patient
eligibility criteria
, the
questionnaires
,
clinician participation
,
funding
and
time
(for the clinicians), and
risks
and
benefits
(for the participants).

Discussion

The trial implementation showed that AR in addition to HA-fitting can be carried out in GCP using the Internet. Using an Internet-based RCT overcomes some of the challenges of implementing a trial in GCP.
Frequency Importance Functions in Quiet and Noise for Adults With Cochlear Implants
Authors: Sladen Douglas P. , Ricketts Todd. A.
Published: July 2015

Purpose

Several studies have been devoted to understanding the frequency information available to adult users of cochlear implants when listening in quiet. The objective of this study was to construct frequency importance functions for a group of adults with cochlear implants and a group of adults with normal hearing both in quiet and in a +10 dB signal-to-noise ratio.

Method

Two groups of adults, 1 with cochlear implants and 1 with normal hearing, were asked to identify nonsense syllables in quiet and in the presence of 6-talker babble while “holes” were systematically created in the speech spectrum. Frequency importance functions were constructed.

Results

Results showed that adults with normal hearing placed greater weight on bands 1, 3, and 4 than on bands 2, 5, and 6, whereas adults with cochlear implants placed equal weight on all bands. The frequency importance functions for each group did not differ between listening in quiet and listening in noise.

Conclusions

Adults with cochlear implants assign perceptual weight toward different frequency bands, though the weight assignment does not differ between quiet and noisy conditions. Generalizing these results to the broader population of adults with implants is constrained by a small sample size.
Cavity‐backed on‐body antenna for customised hearing instrument applications
Authors: Ruaro A. , Thaysen J. , Jakobsen K.B.
Published: July 2015

A novel on‐body antenna targeted for 2.45 GHz customised in‐the‐ear hearing instrument applications is designed, implemented, and measured. The antenna is designed to use the maximum volume available in the user's ear canal and to provide isolation from the user's body. The polarisation is primarily normal to the surface of the head to ensure the best on‐body path gain. Efficiency and S‐parameters from measurements in free space and on a specific anthropomorphic mannequin head endowed with ears are presented.
Three‐leg inverter‐based distribution static compensator topology for compensating unbalanced and non‐linear loads
Authors: Manoj Kumar Manjathu Valappil , Mishra Mahesh Kumar
Published: July 2015

This study proposes a new three‐leg voltage source inverter (VSI)‐based distribution static compensator (DSTATCOM) topology to compensate unbalanced and non‐linear loads in low‐voltage three‐phase four‐wire distribution systems. The proposed topology uses a three‐leg VSI with a single DC storage capacitor. This scheme has an additional small AC capacitor which is connected between negative DC bus to the system neutral. As the proposed topology uses a single DC‐link capacitor, the DC voltage balancing issues associated with the popular split capacitor neutral clamped VSI topology is avoided. Moreover, the topology is able to compensate neutral current without using four‐leg inverter topology. Analysis and modelling of the proposed topology is explained in detail. Simulation studies are carried out to verify the performance of the proposed scheme and results are presented. The performance of the new topology has been compared with conventional three‐leg two level split capacitor VSI‐based DSTATCOM topology. Results are also experimentally verified on a laboratory prototype of DSTATCOM.
Ultrasonography as a Guiding Method in Breast Micro-Calcification Vacuum-Assisted Biopsies
Authors: Keränen A. K. , Haapea M. , Rissanen T.
Published: July 2015

Purpose: To assess the visibility of breast micro-calcifications using ultrasonography (US) and the accuracy and clinical usefulness of vacuum-assisted biopsy (VAB) using US guidance (USVAB) as compared to stereotactic guidance (SVAB).

Materials and Methods: The study material comprised 158 retrospectively reviewed micro-calcification cases examined with US before VAB. The pre-biopsy US positivity frequency distributions were calculated, and the sensitivity, specificity and accuracy of VAB determined by comparing VAB histology with the surgical pathology or a 12-month follow-up.

Results: 158 US examinations yielded 80 positive and 78 negative results. US positivity correlated to a large size and a suspicious BI-RADS category of the calcifications. USVAB was performed in 49 cases with 61 % malignant, 12 % high-risk and 27 % benign results. The percentages for the 109 SVAB cases were 40 %, 28 % and 32 %, respectively. Specimen radiography demonstrated calcifications in 48 of the 49 (98 %) USVAB cases and in 107 of the 109 (98 %) SVAB cases. The overall accuracy of VAB was 94 % (USVAB 98 %, SVAB 94 %), the sensitivity was 88 % (USVAB 97 %, SVAB 83 %), and the specificity was 100 %. The higher sensitivity of USVAB was due to an accumulation of atypical hyperplasia diagnoses in the SVAB group. The final diagnosis was invasive ductal carcinoma in 21 US-positive and in 4 US-negative cases.

Conclusion: Approximately 50 % of mammographically detected micro-calcifications could be detected with ultrasonography. US was found to be a valuable alternative guidance method for vacuum-assisted biopsy of micro-calcifications with a technical success rate and diagnostic accuracy well comparable to the stereotactic method.
Compatibility approach for the improvement of oxide thermoelectric converters for industrial heat recovery applications
Authors: Saucke Gesine , Populoh Sascha , Thiel Philipp , Xie Wenjie , Funahashi Ryoji , Weidenkaff Anke
Published: July 2015

New ceramic Ca3Co3.9O9+δ /CaMn0.97W0.03O3−δ thermoelectric generators with different cross section areas Ap and An of the p- and the n-type leg are fabricated, characterized, and tested at high temperatures in long-term tests. The variation of the measured power output and the efficiency with changing Ap/An ratio is discussed and compared with calculations based on the measured material properties. The highest conversion efficiencies are reached for ratios close to the one predicted by the compatibility approach, whereas an improper choice of Ap/An leads to a strong reduction of the efficiency. A volume power density of 1.4 W/cm3 and an efficiency of 1.08% are found for the most promising generator (temperature difference ΔT= 734 K and Ap/An= 1.12). The results reveal the major importance of the Ap/An ratio for the conversion efficiency and subsequently cost and weight reduction issues, both crucial for a large scale application of thermoelectric converters. Additionally, the oxide generators proved to be very reliable, as after more than 110 h of high temperature energy conversion, no degradation is observable.
Application of the general thermal field model to simulate the behaviour of nanoscale Cu field emitters
Authors: Eimre Kristjan , Parviainen Stefan , Aabloo Alvo , Djurabekova Flyura , Zadin Vahur
Published: July 2015

Strong field electron emission from a nanoscale tip can cause a temperature rise at the tip apex due to Joule heating. This becomes particularly important when the current value grows rapidly, as in the pre-breakdown (the electrostatic discharge) condition, which may occur near metal surfaces operating under high electric fields. The high temperatures introduce uncertainties in calculations of the current values when using the Fowler–Nordheim equation, since the thermionic component in such conditions cannot be neglected. In this paper, we analyze the field electron emission currents as the function of the applied electric field, given by both the conventional Fowler–Nordheim field emission and the recently developed generalized thermal field emission formalisms. We also compare the results in two limits: discrete (atomistic simulations) and continuum (finite element calculations). The discrepancies of both implementations and their effect on final results are discussed. In both approaches, the electric field, electron emission currents, and Joule heating processes are simulated concurrently and self-consistently. We show that the conventional Fowler–Nordheim equation results in significant underestimation of electron emission currents. We also show that Fowler–Nordheim plots used to estimate the field enhancement factor may lead to significant overestimation of this parameter especially in the range of relatively low electric fields.
Efficient maximum likelihood parameterization of continuous-time Markov processes
Authors: McGibbon Robert T. , Pande Vijay S.
Published: July 2015

Continuous-time Markov processes over finite state-spaces are widely used to model dynamical processes in many fields of natural and social science. Here, we introduce a maximum likelihood estimator for constructing such models from data observed at a finite time interval. This estimator is dramatically more efficient than prior approaches, enables the calculation of deterministic confidence intervals in all model parameters, and can easily enforce important physical constraints on the models such as detailed balance. We demonstrate and discuss the advantages of these models over existing discrete-time Markov models for the analysis of molecular dynamics simulations.
Modeling a bus through a sequence of traffic lights
Authors: Villalobos Jorge , Muñoz Víctor , Rogan José , Zarama Roberto , Penagos Juan Felipe , Toledo Benjamín , Valdivia Juan Alejandro
Published: July 2015

We propose a model of a bus traveling through a sequence of traffic lights, which is required to stop between the traffic signals to pick up passengers. A two dimensional model, of velocity and traveled time at each traffic light, is constructed, which shows non-trivial and chaotic behaviors for realistic city traffic parameters. We restrict the parameter values where these non-trivial and chaotic behaviors occur, by following analytically and numerically the fixed points and period 2 orbits. We define conditions where chaos may arise by determining regions in parameter space where the maximum Lyapunov exponent is positive. Chaos seems to occur as long as the ratio of the braking and accelerating capacities are greater than about ∼3.
Photocurrent measurements of pentacene-based devices
Authors: Masurkar Amrita , Kymissis Ioannis
Published: July 2015

Photocurrent spectroscopy (PCS) and photocurrent microscopy (PCM) are powerful tools that can probe the underlying mechanisms of charge generation and transport in organic semiconductor devices. There has been significant progress in the use of these techniques, which has yielded a number of insights into the underlying materials and operation of the devices. Despite the potential for PCS and PCM to become standard tools, however, a consensus has not been reached on (1) its uses and (2) the underlying mechanisms which produce the photoresponse. This is particularly true for measurements of pentacene devices, as the energy dynamics of pentacene are complex. Accordingly, here we report the current body of PCS and PCM of pentacene devices, offer interpretations of the data, and discuss which questions remain unanswered. We have divided the reviewed work into four categories based on the goals of the study and the technique used: photocurrent spectroscopy, scanning photocurrent microscopy, mobility, and trap density-of-states.
Matrix isolation sublimation: An apparatus for producing cryogenic beams of atoms and molecules
Authors: Sacramento R. L. , Oliveira A. N. , Alves B. X. , Silva B. A. , Li M. S. , Wolff W. , Cesar C. L.
Published: July 2015

We describe the apparatus to generate cryogenic beams of atoms and molecules based on matrix isolation sublimation. Isolation matrices of Ne and H2 are hosts for atomic and molecular species which are sublimated into vacuum at cryogenic temperatures. The resulting cryogenic beams are used for high-resolution laser spectroscopy. The technique also aims at loading atomic and molecular traps.
A novel cell weighing method based on the minimum immobilization pressure for biological applications
Authors: Zhao Qili , Shirinzadeh Bijan , Cui Maosheng , Sun Mingzhu , Liu Yaowei , Zhao Xin
Published: July 2015

A novel weighing method for cells with spherical and other regular shapes is proposed in this paper. In this method, the relationship between the cell mass and the minimum aspiration pressure to immobilize the cell (referred to as minimum immobilization pressure) is derived for the first time according to static theory. Based on this relationship, a robotic cell weighing process is established using a traditional micro-injection system. Experimental results on porcine oocytes demonstrate that the proposed method is able to weigh cells at an average speed of 16.3 s/cell and with a success rate of more than 90%. The derived cell mass and density are in accordance with those reported in other published results. The experimental results also demonstrated that this method is able to detect less than 1% variation of the porcine oocyte mass quantitatively. It can be conducted by a pair of traditional micropipettes and a commercial pneumatic micro-injection system, and is expected to perform robotic operation on batch cells. At present, the minimum resolution of the proposed method for measuring the cell mass can be 1.25 × 10−15 kg. Above advantages make it very appropriate for quantifying the amount of the materials injected into or moved out of the cells in the biological applications, such as nuclear enucleations and embryo microinjections.
Sparse maps—A systematic infrastructure for reduced-scaling electronic structure methods. I. An efficient and simple linear scaling local MP2 method that uses an intermediate basis of pair natural orbitals
Authors: Pinski Peter , Riplinger Christoph , Valeev Edward F. , Neese Frank
Published: July 2015

In this work, a systematic infrastructure is described that formalizes concepts implicit in previous work and greatly simplifies computer implementation of reduced-scaling electronic structure methods. The key concept is sparse representation of tensors using chains of sparse maps between two index sets. Sparse map representation can be viewed as a generalization of compressed sparse row, a common representation of a sparse matrix, to tensor data. By combining few elementary operations on sparse maps (inversion, chaining, intersection, etc.), complex algorithms can be developed, illustrated here by a linear-scaling transformation of three-center Coulomb integrals based on our compact code library that implements sparse maps and operations on them. The sparsity of the three-center integrals arises from spatial locality of the basis functions and domain density fitting approximation. A novel feature of our approach is the use of differential overlap integrals computed in linear-scaling fashion for screening products of basis functions. Finally, a robust linear scaling domain based local pair natural orbital second-order Möller-Plesset (DLPNO-MP2) method is described based on the sparse map infrastructure that only depends on a minimal number of cutoff parameters that can be systematically tightened to approach 100% of the canonical MP2 correlation energy. With default truncation thresholds, DLPNO-MP2 recovers more than 99.9% of the canonical resolution of the identity MP2 (RI-MP2) energy while still showing a very early crossover with respect to the computational effort. Based on extensive benchmark calculations, relative energies are reproduced with an error of typically <0.2 kcal/mol. The efficiency of the local MP2 (LMP2) method can be drastically improved by carrying out the LMP2 iterations in a basis of pair natural orbitals. While the present work focuses on local electron correlation, it is of much broader applicability to computation with sparse tensors in quantum chemistry and beyond.
Shear-induced breaking of cages in colloidal glasses: Scattering experiments and mode coupling theory
Authors: Amann Christian P. , Denisov Dmitry , Dang Minh Triet , Struth Bernd , Schall Peter , Fuchs Matthias
Published: July 2015

We employ x-ray scattering on sheared colloidal suspensions and mode coupling theory to study structure factor distortions of glass-forming systems under shear. We find a transition from quadrupolar elastic distortion at small strains to quadrupolar and hexadecupolar modes in the stationary state. The latter are interpreted as signatures of plastic rearrangements in homogeneous, thermalized systems. From their transient evolution with strain, we identify characteristic strain and length-scale values where these plastic rearrangements dominate. This characteristic strain coincides with the maximum of the shear stress versus strain curve, indicating the proliferation of plastic flow. The hexadecupolar modes dominate at the wavevector of the principal peak of the equilibrium structure factor that is related to the cage-effect in mode coupling theory. We hence identify the structural signature of plastic flow of glasses.
Pair correlations in classical crystals: The shortest-graph method
Authors: Yurchenko Stanislav O. , Kryuchkov Nikita P. , Ivlev Alexei V.
Published: July 2015

The shortest-graph method is applied to calculate the pair correlation functions of crystals. The method is based on the representation of individual correlation peaks by the Gaussian functions, summed along the shortest graph connecting the two given points. The analytical expressions for the Gaussian parameters are derived for two- and three-dimensional crystals. The obtained results are compared with the pair correlation functions deduced from the molecular dynamics simulations of Yukawa, inverse-power law, Weeks-Chandler-Andersen, and Lennard-Jones crystals. By calculating the Helmholtz free energy, it is shown that the method is particularly accurate for soft interparticle interactions and for low temperatures, i.e., when the anharmonicity effects are insignificant. The accuracy of the method is further demonstrated by deriving the solid-solid transition line for Yukawa crystals, and the compressibility for inverse-power law crystals.
Percolation in suspensions of polydisperse hard rods: Quasi universality and finite-size effects
Authors: Meyer Hugues , van der Schoot Paul , Schilling Tanja
Published: July 2015

We present a study of connectivity percolation in suspensions of hard spherocylinders by means of Monte Carlo simulation and connectedness percolation theory. We focus attention on polydispersity in the length, the diameter, and the connectedness criterion, and we invoke bimodal, Gaussian, and Weibull distributions for these. The main finding from our simulations is that the percolation threshold shows quasi universal behaviour, i.e., to a good approximation, it depends only on certain cumulants of the full size and connectivity distribution. Our connectedness percolation theory hinges on a Lee-Parsons type of closure recently put forward that improves upon the often-used second virial approximation [T. Schilling, M. Miller, and P. van der Schoot, e-print arXiv:1505.07660 (2015)]. The theory predicts exact universality. Theory and simulation agree quantitatively for aspect ratios in excess of 20, if we include the connectivity range in our definition of the aspect ratio of the particles. We further discuss the mechanism of cluster growth that, remarkably, differs between systems that are polydisperse in length and in width, and exhibits non-universal aspects.
Brans-Dicke-Maxwell solutions for higher dimensional static cylindrical symmetric spacetime
Authors: Çiftci Dilek K. , Delice Özgür
Published: July 2015

In this paper, Brans-Dicke-Maxwell type vacuum solutions are considered for a static cylindrically symmetric spacetime in arbitrary dimensions. Exact solutions are obtained by directly solving the field equations for the case where an azimuthal magnetic field is present. Other configurations such as axial magnetic field case can be obtained by suitably relabeling the coordinates. We have also considered conformally related “Einstein frame” to relate the solutions we have obtained with the dilaton-Maxwell type solutions that exist in the literature. We see that for a special case the general solution we present reduces to dilaton-Melvin spacetime. The general relativistic limit of these solutions is also discussed and we found that this limit is different from the four dimensional case.
Solvent-dependent intramolecular charge transfer delocalization/localization in multibranched push-pull chromophores
Authors: Li Yang , Zhou Meng , Niu Yingli , Guo Qianjin , Xia Andong
Published: July 2015

The effect of the solvent polarity on excitation delocalization/localization in multibranched push-pull chromophores has been thoroughly explored by combining steady state absorption and fluorescence, as well as femtosecond transient spectral measurements. We found that the excited-state relaxations of the push-pull chromophores are highly dependent on both solvent polarity and the polar degree of the excited intramolecular charge transfer states. The symmetry of multibranched chromophores is preserved in less polar solvents, leading to excitation delocalization over all of the branches because of the negligible solvent reaction field. In contrast, symmetry is broken for multibranched chromophores in more polar solvents because of intense solvent reaction field, and the excitation is consequently localized on one of the dipolar molecular branches. The results provide a fundamental understanding of solvent-dependent excitation delocalization/localization properties of the multibranched chromophores for the potential applications in nonlinear optics and energy-harvesting applications.
Spectroscopic and theoretical studies of the low-lying states of BaO+
Authors: Bartlett Joshua H. , VanGundy Robert A. , Heaven Michael C.
Published: July 2015

The BaO+ cation is of interest from the perspectives of electronic structure and the potential for cooling to ultra-cold temperatures. Spectroscopic data for the ion have been obtained using a two-color photoionization technique. The ionization energy for BaO was found to be 6.8123(3) eV. The ground state of BaO+ was identified as X2Σ+, and both vibrational and rotational constants were determined. Vibrationally resolved spectra were recorded for A2Π, the first electronically excited state. These data yielded the term energy, vibrational frequency, and the spin-orbit interaction constant. Relativistic electronic structure calculations were carried out using multi-reference configuration interaction (MRCI), coupled cluster and density functional theory methods. Transition moments for the pure vibrational and A2Π-X2Σ+ transitions were predicted using the MRCI method.
Modeling of anisotropic flow and thermodynamic properties of magnetic nanofluids induced by external magnetic field with varied imposing directions
Authors: Song Dongxing , Jing Dengwei , Luo Bing , Geng Jiafeng , Ren Yuxun
Published: July 2015

Magnetic field can enhance both thermal conductivity and Lorentz force resistance of the magnetic nanofluids (MNFs), in which the former is favored while the latter often leads to pressure drop of the flow. It is assumed that there would exist a balance between the magnetic field induced thermal conductivity and Lorentz force if one can appropriately adjust the angle of the imposing magnetic field with respect to the direction of the flow. In the present study, the effects of direction of magnetic field (α) on anisotropic thermodynamic properties of magnetic nanofluids in channel were studied. The effects of direction of magnetic field on thermal conductivity, Nusselt number, global total entropy generation, and other parameters, such as velocity, temperature, and concentration, have been discussed in detail. A greater α can lead to a larger thermal conductivity normal to the walls of channel and a more uniform temperature field. However, the velocity of magnetic nanofluid tends to decrease. There is a threshold for magnetic intensity (B). When magnetic intensity becomes large than the threshold, its effect on thermal conductivity will tends to be constant. The effect of increase of α is found to be similar to that of increasing Hartmann number (Ha) and both can lead to augment of Lorentz resistance force along flow direction. With the increases of α and Ha, both heat transfer efficiency (Nu) and global total entropy generation (ST) increase. Here, ST indicates the extent of loss of useful work due to the irreversibility of the process. A comprehensive utility index, Iu, is defined for evaluation of the performance of a practical heat transfer system employing MNFs. For the case where the purpose of heat transfer is to cool an equipment such as electrical device, guaranteeing heat transfer efficiency (Nu) is more important than decreasing useful energy loss (ST); thus, we propose a large α relative to the flow direction. For industrial processes, where energy loss (ST) have to be particularly considered, a small α is recommended.
Analysis of impact of building integrated photovoltaic systems on distribution network losses
Authors: Babić Iva , Đurišić Željko , Žarković Mileta
Published: July 2015

The effects of large-scale integration of Building Integrated Photovoltaic systems on power losses in a Distribution Network (DN) have been analyzed. A comparative analysis of three different methods has been carried out. The first applied method is based on the statistical equivalent of the DN and production profiles of the Photovoltaic (PV) systems calculated from the measurement data of 10 min average values of solar irradiation taken for the period of 1 yr. The statistical equivalent of the DN is estimated based on hourly measurements of the injected power in the DN and billed electrical energy. The estimated equivalent statistical resistance is used for DN modeling for the purpose of calculating power losses. Fuzzy numbers are used as the second method of the research for the purpose of faster estimation. The Monte Carlo simulation, as the third method, is used to involve all possible situations of PV production and energy consumption. The economy calculation is made based on the results of power losses' reduction in the DN of Serbia. The proposed methodology is of a general character; however, it can be applied to other power distribution systems.
How to predict the ideal glass transition density in polydisperse hard-sphere packings
Authors: Baranau Vasili , Tallarek Ulrich
Published: July 2015

The formula for the entropy s of the accessible volume of the phase space for frictionless hard spheres is combined with the Boublík–Mansoori–Carnahan–Starling–Leland (BMCSL) equation of state for polydisperse three-dimensional packings to obtain an analytical expression for s as a function of packing density φ. Polydisperse hard-sphere packings with log-normal, Gaussian, and Pareto particle diameter distributions are generated to estimate their ideal glass transition densities φg. The accessible entropy s at φg is almost the same for all investigated particle diameter distributions. We denote this entropy as sg and can predict φg for an arbitrary particle diameter distribution through an equation s(φ) = sg. If the BMCSL equation of state is used for s(φ), then φg is found to depend only on the first three moments of a particle diameter distribution.
Leading order nonadiabatic corrections to rovibrational levels of H2, D2, and T2
Authors: Pachucki Krzysztof , Komasa Jacek
Published: July 2015

An efficient computational approach to nonadiabatic effects in the hydrogen molecule (H2, D2, and T2) is presented. The electronic wave function is expanded in the James-Coolidge basis set, which enables obtaining a very high accuracy of nonadiabatic potentials. A single point convergence of the potentials with growing size of the basis set reveals a relative accuracy ranging from 10−8 to 10−13. An estimated accuracy of the leading nonadiabatic correction to the rovibrational energy levels is of the order of 10−7 cm−1. After a significant increase in the accuracy of the Born-Oppenheimer and adiabatic calculations, the nonadiabatic results presented in this report constitute another step towards highly accurate theoretical description of the hydrogen molecule.
Linear and nonlinear evolution of the ion resonance instability in cylindrical traps: A numerical study
Authors: Sengupta M. , Ganesh R.
Published: July 2015

Numerical experiments have been performed to investigate the linear and nonlinear dynamics, and energetics of the ion resonance instability in cylindrically confined nonneutral plasma. The instability is excited on a set of parametrically different unstable equilibria of a cylindrical nonneutral cloud, composed of electrons partially neutralized by a much heavier ion species of single ionization. A particle-in-cell code has been developed and employed to carry out these simulations. The results obtained from the initial exponential growth phase of the instability in these numerical experiments are in agreement with the linearised analytical model of the ion resonance instability. As the simulations delve much further in time beyond the exponential growth phase, very interesting nonlinear phenomena of the ion resonance instability are revealed, such as a process of simultaneous wave breaking of the excited poloidal mode on the ion cloud and pinching of the poloidal perturbations on the electron cloud. This simultaneous nonlinear dynamics of the two components is associated with an energy transfer process from the electrons to the ions. At later stages there is heating induced cross-field transport of the heavier ions and tearing across the pinches on the electron cloud followed by an inverse cascade of the torn sections.
Physics of the interaction of ultra intense laser pulses with cold collisional plasma using large scale kinetic simulations
Authors: Héron A. , Adam J. C.
Published: July 2015

We present a set of 2D collisional particle-in-cell simulations of the interaction of ultra-intense laser pulses with over-dense cold collisional plasmas. The size of these simulations is about 100 times as large as those previously published. This allows studying the transport of energetic particles on time scale of the order of 400 fs without perturbations due to the influence of boundary effects and performing a very detailed analysis of the physics of the transport. We confirm the existence of a threshold in intensity close to the relativistic threshold above which the beam of energetic particles diverges when it penetrates the cold plasma. We also study the applicability of Ohm's law to compute the electric field, which is the method commonly used in hybrid codes. The heating of the cold plasma is then studied and we show that half of the heating is anomalous, i.e., not given by standard Joule effect. We discuss the previously published results in the light of these new simulations.
Multiple folding pathways of proteins with shallow knots and co-translational folding
Authors: Chwastyk Mateusz , Cieplak Marek
Published: July 2015

We study the folding process in the shallowly knotted protein MJ0366 within two variants of a structure-based model. We observe that the resulting topological pathways are much richer than identified in previous studies. In addition to the single knot-loop events, we find novel, and dominant, two-loop mechanisms. We demonstrate that folding takes place in a range of temperatures and the conditions of most successful folding are at temperatures which are higher than those required for the fastest folding. We also demonstrate that nascent conditions are more favorable to knotting than off-ribosome folding.
Growth and microstructure of columnar Y-doped SrZrO3 films deposited on Pt-coated MgO by pulsed laser deposition
Authors: Luo Sijun , Riggs Brian C. , Zhang Xiaodong , Shipman Joshua T. , Adireddy Shiva , Sklare Samuel C. , Koplitz Brent , Chrisey Douglas B.
Published: July 2015

Direct integration of proton conductor films on Pt-coated substrates opens the way to film-based proton transport devices. Columnar SrZr0.95Y0.05O3−δ (SZY) films with dense microstructure were deposited on Pt-coated MgO(100) substrates at 830 °C by pulsed laser deposition. The optimal window of ambient O2 pressure for good crystallinity of SZY films is from 400 to 600 mTorr. The ambient O2 compresses the plasma plume of SZY and increases the deposition rate. The 10 nm thick Ti adhesion layer on MgO(100) greatly affects the orientation of the sputtered Pt layers. Pt deposited directly on MgO shows a highly (111)-preferred orientation and leads to preferentially oriented SZY films while the addition of a Ti adhesion layer makes Pt show a less preferential orientation that leads to randomly oriented SZY films. The RMS surface roughness of preferentially oriented SZY films is larger than that of randomly oriented SZY films deposited under the same ambient O2 pressure. As the O2 pressure increased, the RMS surface roughness of preferentially oriented SZY films increased, reaching 45.7 nm (2.61% of film thickness) at 600 mTorr. This study revealed the ambient O2 pressure and orientation dependent surface roughness of SZY films grown on Pt-coated MgO substrates, which provides the potential to control the surface microstructure of SZY films for electrochemical applications in film-based hydrogen devices.
Structural properties of Bi2−xMnxSe3 thin films grown via molecular beam epitaxy
Authors: Babakiray Sercan , Johnson Trent A. , Borisov Pavel , Holcomb Mikel B. , Lederman David , Marcus Matthew A. , Tarafder Kartick
Published: July 2015

The effects of Mn doping on the structural properties of the topological insulator Bi2Se3 in thin film form were studied in samples grown via molecular beam epitaxy. Extended x-ray absorption fine structure measurements, supported by density functional theory calculations, indicate that preferential incorporation occurs substitutionally in Bi sites across the entire film volume. This finding is consistent with x-ray diffraction measurements which show that the out of plane lattice constant expands while the in plane lattice constant contracts as the Mn concentration is increased. X-ray photoelectron spectroscopy indicates that the Mn valency is 2+ and that the Mn bonding is similar to that in MnSe. The expansion along the out of plane direction is most likely due to weakening of the Van der Waals interactions between adjacent Se planes. Transport measurements are consistent with this Mn2+ substitution of Bi sites if additional structural defects induced by this substitution are taken into account.
Polarization properties and disorder effects in H3 photonic crystal cavities incorporating site-controlled, high-symmetry quantum dot arrays
Authors: Surrente Alessandro , Felici Marco , Gallo Pascal , Dwir Benjamin , Rudra Alok , Biasiol Giorgio , Kapon Eli
Published: July 2015

We report on the effects of optical disorder on breaking the symmetry of the cavity modes of H3 photonic crystal cavities incorporating site-controlled pyramidal quantum dots (QDs) as the internal light source. The high in-plane symmetry of the polarization states of the pyramidal QDs simplifies the analysis of the polarization states of the H3 cavities. It is shown that the optical disorder induced by fabrication imperfections lifts the degeneracy of the two quadrupole cavity modes and tilts the elongation axes of the cavity mode patterns with respect to the ideal, hexagonal symmetry case. These results are useful for designing QD-cavity structures for polarization-entangled photon sources and few-QD lasers.
Pressure, stress, and strain distribution in the double-stage diamond anvil cell
Authors: Lobanov Sergey S. , Prakapenka Vitali B. , Prescher Clemens , Konôpková Zuzana , Liermann Hanns-Peter , Crispin Katherine L. , Zhang Chi , Goncharov Alexander F.
Published: July 2015

Double stage diamond anvil cells (DACs) of two designs have been assembled and tested. We used a standard symmetric DAC with flat or beveled culets as a primary stage and CVD microanvils machined by a focused ion beam as a second. We evaluated pressure, stress, and strain distributions in gold and a mixture of gold and iron as well as in secondary anvils using synchrotron x-ray diffraction with a micro-focused beam. A maximum pressure of 240 GPa was reached independent of the first stage anvil culet size. We found that the stress field generated by the second stage anvils is typical of conventional DAC experiments. The maximum pressures reached are limited by strains developing in the secondary anvil and by cupping of the first stage diamond anvil in the presented experimental designs. Also, our experiments show that pressures of several megabars may be reached without sacrificing the first stage diamond anvils.
Effects of gas flow on oxidation reaction in liquid induced by He/O2 plasma-jet irradiation
Authors: Nakajima Atsushi , Uchida Giichiro , Kawasaki Toshiyuki , Koga Kazunori , Sarinont Thapanut , Amano Takaaki , Takenaka Kosuke , Shiratani Masaharu , Setsuhara Yuichi
Published: July 2015

We present here analysis of oxidation reaction in liquid by a plasma-jet irradiation under various gas flow patterns such as laminar and turbulence flows. To estimate the total amount of oxidation reaction induced by reactive oxygen species (ROS) in liquid, we employ a KI-starch solution system, where the absorbance of the KI-starch solution near 600 nm behaves linear to the total amount of oxidation reaction in liquid. The laminar flow with higher gas velocity induces an increase in the ROS distribution area on the liquid surface, which results in a large amount of oxidation reaction in liquid. However, a much faster gas flow conversely results in a reduction in the total amount of oxidation reaction in liquid under the following two conditions: first condition is that the turbulence flow is triggered in a gas flow channel at a high Reynolds number of gas flow, which leads to a marked change of the spatial distribution of the ROS concentration in gas phase. Second condition is that the dimpled liquid surface is formed by strong gas flow, which prevents the ROS from being transported in radial direction along the liquid surface.
Dielectric measurements of nanoliter liquids with a photonic crystal resonator at terahertz frequencies
Authors: Hanham S. M. , Watts C. , Otter W. J. , Lucyszyn S. , Klein N.
Published: July 2015

We present a highly sensitive technique for determining the complex permittivity of nanoliter liquid samples in the terahertz band based on a photonic crystal resonator and microcapillary. Liquids are characterized by using a capillary tube to introduce a ∼4 nl liquid sample into the electromagnetic field of a resonant mode confined by an L3 resonant cavity in a high-resistivity silicon photonic crystal slab. Monitoring the perturbation of the resonant frequency and unloaded Q-factor of the resonant mode at 100 GHz and ∼5800, respectively, allows a sample's permittivity to be calculated. An analytical model describing the system response based on perturbation theory and quasi-static analysis of the electric field within the capillary is also presented and found to agree well with FEM simulations and experimental measurements of ethanol-water mixtures of various concentrations for low to moderate loss tangents of the liquid samples. We demonstrate the utility of this approach by measuring the complex permittivity of several bioliquids, including suspensions of red and white blood cells. These results represent a step towards a lab-on-a-chip device for the analysis of extremely small quantities of biological, toxic, explosive, and other liquid types at terahertz frequencies.
Experimental study of electric dipoles on an oxygen-adsorbed Si(100)-2 × 1 surface by non-contact scanning nonlinear dielectric microscopy
Authors: Suzuki Masataka , Yamasue Kohei , Cho Yasuo
Published: July 2015

Oxygen-adsorption on a Si(100)-2 × 1 surface is investigated by using non-contact scanning nonlinear dielectric microscopy (NC-SNDM). On the Si(100)-2 × 1 surface exposed to oxygen (O2) gas at room temperature, several variations in atomic configuration and electric dipole moment of dimers are observed. Models are proposed for oxygen adsorption which are consistent with the topographies and electric dipole moment distributions obtained by NC-SNDM.
Communication: The performance of non-iterative coupled cluster quadruples models
Authors: Eriksen Janus J. , Matthews Devin A. , Jørgensen Poul , Gauss Jürgen
Published: July 2015

We compare the numerical performance of various non-iterative coupled cluster (CC) quadruples models. The results collectively show how approaches that attempt to correct the CC singles and doubles energy for the combined effect of triple and quadruple excitations all fail at recovering the correlation energy of the full CC singles, doubles, triples, and quadruples (CCSDTQ) model to within sufficient accuracy. Such a level of accuracy is only achieved by models that make corrections to the full CC singles, doubles, and triples (CCSDT) energy for the isolated effect of quadruple excitations of which the CCSDT(Q–3) and CCSDT(Q–4) models of the Lagrangian-based CCSDT(Q–n) perturbation series are found to outperform alternative models that add either of the established [Q] and (Q) corrections to the CCSDT energy.
Enhancement of a whispering gallery mode microtoroid resonator by plasmonic triangular gold nanoprism for label-free biosensor applications
Authors: Nadgaran H. , Afkhami Garaei M.
Published: July 2015

Whispering gallery mode microresonators coupled to plasmonic nanoparticles have shown great promise for ultra-sensitive and label-free biological sensing. We analyze a whispering gallery mode microtoroid biosensor with a triangular gold nanoprism bound to its surface. We choose triangular nanoprism because of its capability of considerable enhancement of electromagnetic field at the tips and because its localized surface plasmon resonance band position is readily tunable. The local electric field enhancement at different points of plasmonic triangular gold nanoprism is calculated and the effect of rounded tip is investigated. This field enhancement permits the detection and characterization of some large protein molecules. We have studied the detection of single bovine serum albumin protein using our hybrid microcavity.
Plasmon-enhanced phonon and ionized impurity scattering in doped silicon
Authors: Chen Ming-Jer , Hsieh Shang-Hsun , Chen Chuan-Li
Published: July 2015

Historically, two microscopic electron scattering calculation methods have been used to fit macroscopic electron mobility data in n-type silicon. The first method was performed using a static system that included long-range electron-plasmon scattering; however, the well-known Born approximation fails in this case when dealing with electron-impurity scattering. In the second method, sophisticated numerical simulations were developed around plasmon-excited potential fluctuations and successfully reproduced the mobility data at room temperature. In this paper, we propose a third method as an alternative to the first method. First, using a fluctuating system, which was characterized on the basis of our recently experimentally extracted plasmon-excited potential fluctuations, the microscopic calculations reveal enhanced short-range scattering of electrons by phonons and ionized impurities due to increased electron temperature and increased screening length, respectively. The increased hot electron population makes the Born approximation hold, which eases the overall calculation task substantially. Then, we return to the static system while incorporating plasmon-enhanced impurity scattering. The resulting macroscopic electron mobility shows fairly good agreement with data over wide ranges of temperatures (200–400 K) and doping concentrations (1015–1020 cm−3). Application of the proposed method to strained silicon is also demonstrated.
The down-conversion and up-conversion photoluminescence properties of Na0.5Bi0.5TiO3:Yb3+/Pr3+ ceramics
Authors: Huang Yinpeng , Luo Laihui , Wang Jia , Zuo Qianghui , Yao Yongjie , Li Weiping
Published: July 2015

Na0.5Bi0.5−x−yYbxPryTiO3 (NBT:xYb/yPr) ceramics with different Yb and Pr contents are prepared. Both the down-conversion (DC) and up-conversion (UC) photoluminescence (PL) of the ceramics via 453 and 980 nm excitation, respectively, are investigated. The effect of Yb3+ and Pr3+ doping contents on the DC and UC PL is significantly different from each other. Furthermore, the UC PL of the ceramics as a function of temperatures is measured to investigate the UC process in detail. Based on energy level diagram of Pr3+ and Yb3+ ions and the DC and UC PL spectra, the DC and UC PL mechanisms of Pr3+ and Yb3+ ions are discussed. Especially, the UC PL mechanism is clarified, which is different from the previously reported literature. Also, the temperature sensing properties of the ceramics are studied based on the photoluminescence ratio technique, using the thermal coupling energy levels of Pr3+.