bluuebunny/crossref_metadata_2025 huggingface dataset:
RVIP: an indistinguishable approach to scalable network simulation at real time
Authors: Kong Jiejun , Li Tingzhen , Wu Dapeng Oliver
Published: July 2014

In the hybrid simulation research, we investigate a new approach to build software virtual networks (SVNs) that are indistinguishable from their equivalent real live networks (LNs). We define the concept of ‘Network's Interactive Turing Test' based on the similar concept used in the artificial intelligence areas. Our goal is to actualize the interactive and indistinguishable real–virtual interface pair (RVIP) for large‐scale computer network simulations. By RVIP's support, a single SVN is indistinguishable from its equivalent LN. In the entire hybrid system, multiple LNs and multiple SVNs are connected using many RVIPs in an arbitrary topology and at real time. To actualize RVIP, the following necessary conditions must be satisfied: (i) the performance of the underlying simulation platform must be faster than real time; (ii) all needed changes incurred by introducing any SVN into an LN scenario are put on the simulation's side. To interact with an SVN, RVIP requires that no change is made on any live node; (iii) an SVN does not exchange simulation events with LNs, that is, only standard IP protocol interactions between SVN and LN are allowed. (iv) Any LN can be dynamically plugged into the hybrid scenario at real time, just like being plugged into an equivalent purely LN. Compared with existing hybrid simulation efforts on NS‐3, QualNet's EXata and OPNET's system‐in‐the‐loop, in this paper, we use the actual RVIP implementation to show that RVIP is a better candidate to pass the Network's Interactive Turing Test owing to the following two advantages: (i) an interactive network tester can easily distinguish the existing hybrid networks from the LNs by using a live topology that cannot be simulated, for example, by including the entire live Internet. But RVIP is not vulnerable to such tests. RVIP can support hybrid scenarios with multiple SVNs and multiple LNs connected by an arbitrary network topology, and with the LNs on and off at anytime. (ii) Performance‐wise, our studies show that RVIP provides more efficient support in terms of common metrics such as larger throughput limit and smaller extra latency; thus, the simulated SVNs are more indistinguishable from their live counterparts. Copyright © 2014 John Wiley & Sons, Ltd.
A node division location detection scheme for chain‐type wireless sensor networks
Authors: Chen Guangzhu , Bao Jiusheng , Zhang Lei
Published: July 2014

As a special type of wireless sensor network, the chain‐type wireless sensor networks can be used to monitor narrow and long regions, such as roads, underground mine tunnels, rivers, and bridges. In this study, a perpendicular bisector division (PB) method was first presented, in which the location may be divided into more location sub‐areas by a perpendicular bisector of each of two location nodes. Compared with the triangulation division method in Approximate Point‐in‐Triangulation Test (APIT), the computable complexity of PB is lower, and the number of division areas is larger. Furthermore, in order to locate targets under rare location nodes, a virtual location node‐perpendicular bisector division (VPB) was presented by a virtual location node based on the geographic shape of the monitored area. Virtual location nodes increase the density of location nodes, which can improve the accuracy of the location in the location algorithm. Second, two range‐free location algorithms were proposed: the location algorithm based on PB (LAPB) and the location algorithm based on VPB (LAVPB). In the end, the location errors performance of APIT, LAPB, and LAVPB for locating miners in an underground mine tunnel was tested. The results show that LAPB and LAVPB have higher location accuracy and are more robust than APIT. LAVPB is more suitable for locating targets in harsh environments. Copyright © 2014 John Wiley & Sons, Ltd.
Prediction‐based MAC‐layer sensing in cognitive radio networks
Authors: Zhang Lei , Xie Cihang , Jiang Tao , Shen Junyang , Qi Qi , Meng Dexiang
Published: July 2014

We consider a cognitive radio network which coexists with multiple primary users (PUs) and secondary users (SUs) transmit over time‐varying channels. In this scenario, one problem of the existing work is the poor performances of throughput and fairness due to variances of SUs' channel conditions and PUs' traffic patterns. To solve this problem, we propose a novel prediction‐based MAC‐layer sensing algorithm. In the proposed algorithm, the SUs' channel quality information and the probability of the licensed channel being idle are predicted. Through the earlier predicted information, we schedule the SUs to sense and transmit on different licensed channels. Specifically, multiple significant factors, including network throughput and fairness, are jointly considered in the proposed algorithm. Then, we formulate the prediction‐based sensing scheduling problem as an optimization problem and solve it with the Hungarian algorithm in polynomial time. Simulation results show that the proposed prediction‐based sensing scheduling algorithm could achieve a good tradeoff between network throughput and fairness among SUs. Copyright © 2014 John Wiley & Sons, Ltd.
Performance analysis of channel estimation in amplify‐and‐forward multi‐hop direct forwarding wireless networks
Authors: Choi Jeong‐Min , Baek Jong‐Seob , Han Jae‐Shin , Seo Jong‐Soo
Published: July 2014

In this paper, we study the performance of a training‐based least square (LS) and linear minimum mean‐square‐error (LMMSE) channel estimation for both hop‐by‐hop and multi‐hop direct forwarding wireless sensor networks over frequency‐selective fading channels. Specifically, to investigate the properties of the channel estimation, we accomplish a theoretical analysis of MSE in terms of various link parameters. From the performance evaluation, we analytically present the effects of the number of hops on the MSE performance for channel estimations in both multi‐hop networks. Interesting observations of MSE behaviors under various conditions are discussed, and the receiver complexity and channel equalization performance are also analyzed. Finally, through the computer simulations, the analytical results and detection performance are demonstrated. Copyright © 2014 John Wiley & Sons, Ltd.
Irinophore C™, a lipid nanoparticle formulation of irinotecan, abrogates the gastrointestinal effects of irinotecan in a rat model of clinical toxicities
Authors: Waterhouse Dawn N. , Sutherland Brent W. , Santos Nancy Dos , Masin Dana , Osooly Maryam , Strutt Dita , Ostlund Christina , Anantha Malathi , Harasym Natashia , Manisali Irina , Wehbe Mohamed , Bally Marcel B. , Webb Murray S.
Published: July 2014

Irinotecan is a water-soluble camptothecin derivative with clinical activity against colorectal and small cell lung cancers and is currently a standard of care therapeutic in the treatment of colorectal cancer in combination with 5-fluorouracil. One of the major clinical issues limiting the use of irinotecan is gastrointestinal toxicity manifested as life-threatening diarrhea which is reported in up to 45 % of treated patients. The studies summarized here tested, in a rat model of irinotecan-associated gastro-intestinal toxicity, whether a lipid nanoparticle formulation of irinotecan, Irinophore C™, mitigated early-onset or late-onset diarrhea when given at doses equivalent to unformulated irinotecan that engenders both early- and late-onset diarrhea. Specifically, rats administered intravenously on two consecutive days with unformulated irinotecan at 170 mg/kg then 160 mg/kg experienced transient early-onset diarrhea after each administration and then experienced significant late-onset diarrhea peaking 4 days after treatment. Irinophore C™ given at the identical dose and schedule did not elicit either early- or late-onset diarrhea in any animals. When Irinophore C™ was combined with 5-fluorouracil there was also no early- or late-onset diarrhea observed. Histopathological analysis of the gastro-intestinal tract confirmed that the effects associated with irinotecan treatment were absent in rats given Irinophore C™ at the identical dose. Pharmacokinetic analysis demonstrated significantly higher systemic concentrations of irinotecan in rats given the nanoparticle formulation compared to those given unformulated irinotecan. These results demonstrate that the Irinophore C™ formulation is significantly less toxic than irinotecan, used either as a single agent or in combination with 5-fluorouracil, in a rat model of irinotecan-induced gastrointestinal toxicity.
A Historical Perspective of the Effect of the Great Recession on Hospitals
Authors: Shortt Janet
Published: July 2014

At 18 months, the Great Recession of December 2007 to June 2009 is the longest recession since World War II. The recession led to soaring unemployment, resulting in loss of employment‐based health insurance for millions of people. In addition to seeing increases in uninsured patients, hospitals experienced losses in their investment portfolios, which in turn increased bad debt, charity care, and uncompensated care nationwide. Hospital executives began to devise cost‐cutting strategies to balance the rising debt, such as standardizing medical equipment, cutting staff positions, and delaying construction projects and capital expenditures as well as implementing value analysis strategies. The recession is officially over, and, although economic recovery has been slow and unemployment continues to be an issue, hospitals’ net revenue started improving as of 2009 and hospital construction started increasing in 2010. Still, caution is warranted in the postrecession climate, because it is unknown what effects will be seen when the Baby Boomer generation begins using Medicare.
How Hemostatic Agents Interact With the Coagulation Cascade
Authors: Overbey Douglas M. , Jones Edward L. , Robinson Thomas N.
Published: July 2014

Hemostasis is a critical component of the preservation of hemodynamic stability and operative visibility during surgery. Initially, hemostasis is achieved via the careful application of direct pressure to allow time for the coagulation cascade to create a fibrin and platelet plug. Other first‐line methods of hemostasis in surgery include repair or ligation of the bleeding vessel with sutures, clips, or staples and coagulation of the bleeding site with a thermal energy‐based device. When these methods are insufficient to provide adequate hemostasis, topical hemostatic agents can be used to augment the creation of a clot during surgery. A basic understanding of how and where these products interact with the coagulation cascade is essential to achieving optimal hemostasis outcomes.
Hemostatic Agents: A Guide to Safe Practice for Perioperative Nurses
Authors: Camp Margaret A.
Published: July 2014

Perioperative hemostasis, the effective management of bleeding during operative and other invasive procedures, can involve the use of blood, blood products, and hemostatic agents to augment the patient's natural clotting abilities. Currently, more than 50 hemostatic products are available in the marketplace and dozens more are in development. It is important for perioperative nurses to understand each of the hemostatic agent categories and their actions, properties, applications, and limitations. This article provides an overview of the normal coagulation process (ie, clotting cascade) that is activated by the body when there is a bleeding episode; the management of blood products and the rationale for reducing their use; the financial implications of hemostatic agent use; and how these agents are used, their clinical indications, and potential complications from their use.
Safety and Usability of Hemostats, Sealants, and Adhesives
Authors: Burks Sandra , Spotnitz William
Published: July 2014

Hemostats, sealants, and adhesives are an integral part of surgical patient care. Nurses who have knowledge about these agents can better help ensure safe, efficient surgical patient care. As a caregiver and patient advocate, the perioperative nurse must understand the most current information about these agents and be prepared to facilitate the transfer of this knowledge to all caregivers. Information about these agents, including the contraindications, warnings, and precautions associated with their use as well as their preparation and application, is provided here. Algorithms designed to clarify the best options for using hemostats, sealants, and adhesives are included as well.
Clinical Issues‐August 2014
Authors: Wood Amber , Conner Ramona L. , Bruley Mark E. , Lavanchy Chris , Horvath Gail M.
Published: July 2014

This Month

Cyanoacrylate microbial sealants

Key words: sealant, microbial sealant, surgical site infections, SSIs.

Enhanced environmental cleaning

Key words: cleaning, enhanced cleaning, multidrug‐resistant organisms, MDROs, infection transmission.

Antibiotic stewardship programs

Key words: stewardship, stewardship programs, antibiotics, multidrug‐resistant organisms, MDROs, Clostridium difficile, C diff.

Blanket‐warming cabinet temperature settings

Key words: blankets, warming, temperature settings, warming cabinets.
Dependence in Alzheimer's disease and service use costs, quality of life, and caregiver burden: The DADE study
Authors: Jones Roy W. , Romeo Renee , Trigg Richard , Knapp Martin , Sato Azusa , King Derek , Niecko Timothy , Lacey Loretto ,   DADE Investigator Group
Published: July 2014

Background

Most models determining how patient and caregiver characteristics and costs change with Alzheimer's disease (AD) progression focus on one aspect, for example, cognition. AD is inadequately defined by a single domain; tracking progression by focusing on a single aspect may mean other important aspects are insufficiently addressed. Dependence has been proposed as a better marker for following disease progression.

Methods

This was a cross‐sectional observational study (18 UK sites). Two hundred forty‐nine community or institutionalized patients, with possible/probable AD, Mini‐Mental State Examination (3–26), and a knowledgeable informant participated.

Results

Significant associations noted between dependence (Dependence Scale [DS]) and clinical measures of severity (cognition, function, and behavior). Bivariate and multivariate models demonstrated significant associations between DS and service use cost, patient quality of life, and caregiver perceived burden.

Conclusion

The construct of dependence may help to translate the combined impact of changes in cognition, function, and behavior into a more readily interpretable form. The DS is useful for assessing patients with AD in clinical trials/research.
Psychosocial telephone intervention for dementia caregivers: A randomized, controlled trial
Authors: Tremont Geoffrey , Davis Jennifer D. , Papandonatos George D. , Ott Brian R. , Fortinsky Richard H. , Gozalo Pedro , Yue Mun Sang , Bryant Kimberly , Grover Christine , Bishop Duane S.
Published: July 2014

Background

Identifying effective and accessible interventions for dementia caregivers is critical as dementia prevalence increases.

Objective

Examine the effects of a telephone‐based intervention on caregiver well‐being.

Design

Randomized, controlled trial.

Setting

Academic medical center.

Participants

Two hundred and fifty distressed, family, dementia caregivers.

Intervention

Caregivers randomized to receive 16 telephone contacts over 6 months of either the Family Intervention: Telephone Tracking—Caregiver (FITT‐C) or Telephone Support (TS).

Outcome

Primary outcome variables were family caregivers' depressive symptoms, burden, and reactions to care recipients' behavior problems at 6 months.

Results

The FITT‐C intervention resulted in significantly improved caregiver depressive symptoms (P = .003; 27% net improvement) and less severe reactions to care‐recipient depressive behaviors (P = .009; 29% net improvement) compared with the control condition (TS).

Conclusion

An entirely telephone‐based intervention improves caregivers' depressive symptoms and reactions to behavior problems in the care recipient and is comparable with reported results of face‐to‐face interventions.
Economies of extremes: Lessons from venture‐capital decision making
Authors: de Treville Suzanne , Petty Jeffrey S. , Wager Stefan
Published: July 2014

An organization's ability to exploit extreme events—such as exceptional opportunities—depends on its capacity strategy. The venture capital industry illustrates the interplay of expensive capacity and negative externalities from high utilization. The cost of adding a venture capitalist provides a strong incentive to run lean, but such leanness may make it impossible to evaluate all interesting investment opportunities. Using concepts from extreme‐value theory, we analyze the trade‐off between the costs and benefits arising from an increase in the number of evaluated deals. We ground our analysis in 11 years of archival data from a venture capital firm, representing 3631 deals, the decisions made, the reasons for those decisions, and the decision lead times. The firm identified 20% of arriving deals as worth evaluating during the screening process, but was not able to evaluate approximately 9% of those interesting deals due to a lack of capacity. We show that the value of increasing the number of deals evaluated increases with the tail weight of the distribution of deal values. When the right tail is light, increasing the number of deals evaluated may provide too modest a benefit to justify the cost. When, however, the right tail is heavy, the value of increasing the number of deals is likely to more than compensate for the cost of capacity. Our results provide new insight into the relative value of a chase capacity strategy that emphasizes responsiveness versus a high‐utilization heuristic that emphasizes productivity. Our approach can be applied to other search operations such as personnel selection, quality circles seeking to identify root causes, and making employee capacity available for innovation.
Obsession with status and ressentiment: Historical backgrounds of the Russian discursive identity construction
Authors: Malinova Olga
Published: July 2014

This article analyzes the role of ressentiment in the long-term historical process of Russia’s collective self-identification vis-à-vis “the West”. It argues that ressentiment was persistently generated by the structure of this relationship as long as Russia’s aspiration for an equal status continually proved to be unrealistic. This induced different discursive strategies that are described by social identity theory (SIT) as social mobility, social creativity and social competition. As a motivating factor for the development of these strategies, on the one hand, and a recurrent consequence of their invalidity on the other, ressentiment became a considerable driving force of discourse about Russian identity.
Orbital Roof Fracture and Orbital Cellulitis Secondary to Halo Pin Penetration: Case Report
Authors: Menon K. Venugopal , Al Rawi Asif Esam , Taif Sawsan , Al Ghafri Khalifa , Mollahalli Kishore Kumar
Published: July 2014

Study Design

Case report.

Objective

To report and discuss a rare complication after a patient was treated conservatively with a halo vest.

Methods

A 51-year-old man sustained a hangman's injury of the C2 vertebra following a motor vehicle collision. He was treated conservatively in a halo vest appliance and following mobilization was discharged from the hospital. Two weeks after discharge, the patient presented to the emergency department complaining of proptosis, ptosis, diplopia, and pin loosening. He was readmitted to the hospital, the halo vest was removed, and urgent imaging studies including computed tomography scan and magnetic resonance imaging were performed. They revealed that one of the halo pins had penetrated the orbital roof with active infection of the extraocular soft tissues. In consultation with the ophthalmologist, he was treated conservatively with antibiotics for 10 days.

Results

His ophthalmologic complaints resolved gradually and his eye returned to normal appearance and function. In the meantime, he was immobilized in a sterno-occipital mandibular immobilizer brace.

Conclusion

Though rare, penetrating injuries after cranial pin insertion can occur. Halo devices must be applied by, or under close supervision of, experienced personnel to avoid such complications, and halo vests should be reviewed frequently to detect such incidents early.
Photoluminescence in Pb0.95Sr0.05(Zr1−xTix)1−yCryO3 ferroelectric ceramic system
Authors: Hernández-García M. , Durruthy-Rodríguez M. D. , Costa-Marrero J. , Calderón-Piñar F. , Guerra J. D. S. , Yañez-Limón J. M.
Published: July 2014

Over the past several years, there has been a remarkable growth and development in new ceramic and/or composite materials to be used in the electro-electronic industry. Ferroelectric materials have been recognized for their multifunctional physical properties; also, their optical properties are a subject of intense research effort due to their possible electro-optic applications. In this work, the visible photoluminescence effect is analyzed at room temperature in a sintered Pb0.95Sr0.05(Zr1−xTix)1−yCryO3 perovskite-type structure system, doped with Sr and Cr. The excitation bands used were 267, 325, 373, 457, 635, and 680 nm, but the best result was obtained at 373 nm. The intensity and energy of such emission in this system have been studied by changing the molar Cr concentration (0 < y < 0.005) and the Ti content (x), with x = 0.20, 0.40, 0.53, 0.60, and 0.80, on both sides of the morphotropic phase boundary (MPB) zone. The principal emission bands are at the energies 1.73, 1.87, and 3.03 eV. The changes that were caused by Zr or Ti ions in the symmetry presented in the rhombohedral or tetragonal side of the MPB are more important. Additionally, structural and micro-structural measurements were performed by the x-ray diffraction and scanning electron microscopy techniques, respectively. The micro-Raman technique is also used in the study of this set of samples, which allows finding the Raman shift modes and the influence on the structural changes of the dopants.
Detection of miniband formation in strain-balanced InGaAs/GaAsP quantum well solar cells by using a piezoelectric photothermal spectroscopy
Authors: Aihara Taketo , Fukuyama Atsuhiko , Yokoyama Yuki , Kojima Michiya , Suzuki Hidetoshi , Sugiyama Masakazu , Nakano Yoshiaki , Ikari Tetsuo
Published: July 2014

To investigate the effect of the miniband formation on the optical absorption spectrum, we adopted two non-destructive methodologies of piezoelectric photothermal (PPT) and photoreflectance (PR) spectroscopies for strain-balanced InGaAs/GaAsP multiple quantum-well (MQW) and superlattice (SL) structures inserted GaAs p-i-n solar cells. Because the barrier widths of the SL sample were very thin, miniband formations caused by coupling the wave functions between adjacent wells were expected. From PR measurements, a critical energy corresponding to the inter-subband transition between first-order electron and hole subbands was estimated for MQW sample, whereas two critical energies corresponding to the mini-Brillouin-zone center (Γ) and edge (π) were obtained for SL sample. The miniband width was calculated to be 19 meV on the basis of the energy difference between Γ and π. This coincided with the value of 16 meV calculated using the simple Kronig–Penney potential models. The obtained PPT spectrum for the SL sample was decomposed into the excitonic absorption and inter-miniband transition components. The latter component was expressed using the arcsine-like signal rise corresponding to the Γ point in the mini-Brillouin zone that was enhanced by the Sommerfeld factor. The usefulness of the PPT methodology for investigating the inserted MQW and/or SL structure inserted solar cells is clearly demonstrated.
Spatial assignment of symmetry adapted perturbation theory interaction energy components: The atomic SAPT partition
Authors: Parrish Robert M. , Sherrill C. David
Published: July 2014

We develop a physically-motivated assignment of symmetry adapted perturbation theory for intermolecular interactions (SAPT) into atom-pairwise contributions (the A-SAPT partition). The basic precept of A-SAPT is that the many-body interaction energy components are computed normally under the formalism of SAPT, following which a spatially-localized two-body quasiparticle interaction is extracted from the many-body interaction terms. For electrostatics and induction source terms, the relevant quasiparticles are atoms, which are obtained in this work through the iterative stockholder analysis (ISA) procedure. For the exchange, induction response, and dispersion terms, the relevant quasiparticles are local occupied orbitals, which are obtained in this work through the Pipek-Mezey procedure. The local orbital atomic charges obtained from ISA additionally allow the terms involving local orbitals to be assigned in an atom-pairwise manner. Further summation over the atoms of one or the other monomer allows for a chemically intuitive visualization of the contribution of each atom and interaction component to the overall noncovalent interaction strength. Herein, we present the intuitive development and mathematical form for A-SAPT applied in the SAPT0 approximation (the A-SAPT0 partition). We also provide an efficient series of algorithms for the computation of the A-SAPT0 partition with essentially the same computational cost as the corresponding SAPT0 decomposition. We probe the sensitivity of the A-SAPT0 partition to the ISA grid and convergence parameter, orbital localization metric, and induction coupling treatment, and recommend a set of practical choices which closes the definition of the A-SAPT0 partition. We demonstrate the utility and computational tractability of the A-SAPT0 partition in the context of side-on cation-π interactions and the intercalation of DNA by proflavine. A-SAPT0 clearly shows the key processes in these complicated noncovalent interactions, in systems with up to 220 atoms and 2845 basis functions.
Angle of incidence averaging in reflectance measurements with optical microscopes for studying layered two-dimensional materials
Authors: Saigal Nihit , Mukherjee Amlan , Sugunakar Vasam , Ghosh Sandip
Published: July 2014

Reflectance spectrum measured using an optical microscope with a large numerical aperture objective lens is shown to get modified. The change is most prominent when there are optical interference related features in the spectrum. This modification is shown to arise primarily due to the wide range of angles of incidence involved in the measurement and a simple formulation is provided to correct for this in simulations. The importance of such analysis is brought out through a reflectance contrast spectroscopy based study for identifying mono-layer and bi-layer graphene and MoS2.
Automatic location of disruption times in JET
Authors: Moreno R. , Vega J. , Murari A. ,   JET EFDA Contributors
Published: July 2014

The loss of stability and confinement in tokamak plasmas can induce critical events known as disruptions. Disruptions produce strong electromagnetic forces and thermal loads which can damage fundamental components of the devices. Determining the disruption time is extremely important for various disruption studies: theoretical models, physics-driven models, or disruption predictors. In JET, during the experimental campaigns with the JET-C (Carbon Fiber Composite) wall, a common criterion to determine the disruption time consisted of locating the time of the thermal quench. However, with the metallic ITER-like wall (JET-ILW), this criterion is usually not valid. Several thermal quenches may occur previous to the current quench but the temperature recovers. Therefore, a new criterion has to be defined. A possibility is to use the start of the current quench as disruption time. This work describes the implementation of an automatic data processing method to estimate the disruption time according to this new definition. This automatic determination allows both reducing human efforts to locate the disruption times and standardizing the estimates (with the benefit of being less vulnerable to human errors).
Increasing spin-flips and decreasing cost: Perturbative corrections for external singles to the complete active space spin flip model for low-lying excited states and strong correlation
Authors: Mayhall Nicholas J. , Head-Gordon Martin
Published: July 2014

An approximation to the spin-flip extended configuration interaction singles method is developed using a second-order perturbation theory approach. In addition to providing significant efficiency advantages, the new framework is general for an arbitrary number of spin-flips, with the current implementation being applicable for up to around 4 spin-flips. Two new methods are introduced: one which is developed using non-degenerate perturbation theory, spin-flip complete active-space (SF-CAS(S)), and a second quasidegenerate perturbation theory method, SF-CAS(S)1. These two approaches take the SF-CAS wavefunction as the reference, and then perturbatively includes the effect of single excitations. For the quasidegenerate perturbation theory method, SF-CAS(S)1, the subscripted “1” in the acronym indicates that a truncated denominator expansion is used to obtain an energy-independent down-folded Hamiltonian. We also show how this can alternatively be formulated in terms of an extended Lagrangian, by introducing an orthonormality constraint on the first-order wavefunction. Several numerical examples are provided, which demonstrate the ability of SF-CAS(S) and SF-CAS(S)1 to describe bond dissociations, singlet-triplet gaps of organic molecules, and exchange coupling parameters for binuclear transition metal complexes.
Generation and structure of extremely large clusters in pulsed jets
Authors: Rupp Daniela , Adolph Marcus , Flückiger Leonie , Gorkhover Tais , Müller Jan Philippe , Müller Maria , Sauppe Mario , Wolter David , Schorb Sebastian , Treusch Rolf , Bostedt Christoph , Möller Thomas
Published: July 2014

Extremely large xenon clusters with sizes exceeding the predictions of the Hagena scaling law by several orders of magnitude are shown to be produced in pulsed gas jets. The cluster sizes are determined using single-shot single-particle imaging experiments with short-wavelength light pulses from the free-electron laser in Hamburg (FLASH). Scanning the time delay between the pulsed cluster source and the intense femtosecond x-ray pulses first shows a main plateau with size distributions in line with the scaling laws, which is followed by an after-pulse of giant clusters. For the extremely large clusters with radii of several hundred nanometers the x-ray scattering patterns indicate a grainy substructure of the particles, suggesting that they grow by cluster coagulation.
A novel fast-neutron detector concept for energy-selective imaging and imaging spectroscopy
Authors: Cortesi M. , Dangendorf V. , Zboray R. , Prasser H.-M.
Published: July 2014

We present and discuss the operational principle of a new fast-neutron detector concept suitable for either energy-selective imaging or for imaging spectroscopy. The detector is comprised of a series of energy-selective stacks of converter foils immersed in a noble-gas based mixture, coupled to a position-sensitive charge readout. Each foil in the various stacks is made of two layers of different thicknesses, fastened together: a hydrogen-rich (plastic) layer for neutron-to-proton conversion, and a hydrogen-free coating to selectively stop/absorb the recoil protons below a certain energy cut-off. The neutron-induced recoil protons, that escape the converter foils, release ionization electrons in the gas gaps between consecutive foils. The electrons are then drifted towards and localized by a position-sensitive charge amplification and readout stage. Comparison of the images detected by stacks with different energy cut-offs allows energy-selective imaging. Neutron energy spectrometry is realized by analyzing the responses of a sufficient large number of stacks of different energy response and unfolding techniques. In this paper, we present the results of computer simulation studies and discuss the expected performance of the new detector concept. Potential applications in various fields are also briefly discussed, in particularly, the application of energy-selective fast-neutron imaging for nuclear safeguards application, with the aim of determining the plutonium content in Mixed Oxide (MOX) fuels.
Integrability properties of the dispersionless Kadomtsev-Petviashvili hierarchy
Authors: Fu Wei , Ilangovane R. , Tamizhmani K. M. , Zhang Da-jun
Published: July 2014

In the paper, we investigate integrability characteristics for the dispersionless Kadomtsev-Petviashvili hierarchy. These characteristics include symmetries, Hamiltonian structures, and conserved quantities. We give a Lax triad to construct a master symmetry and a hierarchy of non-isospectral dispersionless Kadomtsev-Petviashvili flows. These non-isospectral flows, together with the known isospectral dispersionless Kadomtsev-Petviashvili flows, form a Lie algebra, which is used to derive two sets of symmetries for the isospectral dispersionless Kadomtsev-Petviashvili hierarchy. By means of the master symmetry, symmetries, Noether operator, and conserved covariants, Hamiltonian structures are constructed for both isospectral and non-isospectral dispersionless Kadomtsev-Petviashvili hierarchies. Finally, two sets of conserved quantities and their Lie algebra are derived for the isospectral dispersionless Kadomtsev-Petviashvili hierarchy.
Demonstrated high performance of gas-filled rugby-shaped hohlraums on Omega
Authors: Philippe F. , Tassin V. , Depierreux S. , Gauthier P. , Masson-Laborde P. E. , Monteil M. C. , Seytor P. , Villette B. , Lasinski B. , Park H. S. , Ross J. S. , Amendt P. , Döppner T. , Hinkel D. E. , Wallace R. , Williams E. , Michel P. , Frenje J. , Gatu-Johnson M. , Li C. K. , Petrasso R. , Glebov V. , Sorce C. , Stoeckl C. , Nikroo A. , Giraldez E.
Published: July 2014

A direct experimental comparison of rugby-shaped and cylindrical shaped gas-filled hohlraums on the Omega laser facility demonstrates that higher coupling and minimal backscatter can be achieved in the rugby geometry, leading to significantly enhanced implosion performance. A nearly 50% increase of x-ray drive is associated with earlier bangtime and increase of neutron production. The observed drive enhancement from rugby geometry in this study is almost twice stronger than in previously published results.
Effect of smectic short-range order on the discontinuous anchoring transition in nematic liquid crystals
Authors: Sai D. Venkata , Kumar T. Arun , Haase W. , Roy Arun , Dhara Surajit
Published: July 2014

We report studies on the temperature dependent alignment behavior of a homologous series of trans, trans- 4, 4′-dialkyl-(1α,1′ α-bicyclohexyl)-4β-carbonitrile (CCNs) on a perfluoropolymer coated cells. Among six compounds in the series, one (CCN-35) has only nematic phase and the remaining five have either smectic-A or smectic-B in addition to the nematic phase. We simultaneously performed temperature dependent dielectric measurements and optical polarising microscope observation. It is found that except for CCN-35 and CCN-73, the remaining four compounds exhibit discontinuous anchoring transition from planar to homeotropic and vice versa with increasing thermal hysteresis. We developed a simple theory taking into account the effect of smectic short-range order at the substrates to explain the experimental observations.
Simulating signatures of two-dimensional electronic spectra of the Fenna-Matthews-Olson complex: By using a numerical path integral
Authors: Liang Xian-Ting
Published: July 2014

A framework for simulating electronic spectra from photon-echo experiments is constructed by using a numerical path integral technique. This method is non-Markovian and nonperturbative and, more importantly, is not limited by a fixed form of the spectral density functions of the environment. Next, a two-dimensional (2D) third-order electronic spectrum of a dimer system is simulated. The spectrum is in agreement with the experimental and theoretical results previously reported [for example, M. Khalil, N. Demirdöven, and A. Tokmakoff, Phys. Rev. Lett. 90, 047401 (2003)]. Finally, a 2D third-order electronic spectrum of the Fenna-Matthews-Olson (FMO) complex is simulated by using the Debye, Ohmic, and Adolphs and Renger spectral density functions. It is shown that this method can clearly produce the spectral signatures of the FMO complex by using only the Adolphs and Renger spectral density function. Plots of the evolution of the diagonal and cross-peaks show that they are oscillating with the population time.
Inductive crystal field control in layered metal oxides with correlated electrons
Authors: Balachandran P. V. , Cammarata A. , Nelson-Cheeseman B. B. , Bhattacharya A. , Rondinelli J. M.
Published: July 2014

We show that the NiO6 crystal field energies can be tailored indirectly via heterovalent A cation ordering in layered (La,A)NiO4 Ruddlesden–Popper (RP) oxides, where A = Sr, Ca, or Ba, using density functional calculations. We leverage as a driving force the electrostatic interactions between charged [LaO]1 + and neutral [AO]0 planes to inductively tune the Ni–O bond distortions, without intentional doping or epitaxial strain, altering the correlated d-orbital energies. We use this strategy to design cation ordered LaCaNiO4 and LaBaNiO4 with distortions favoring enhanced Ni eg orbital polarization, and find local electronic structure signatures analogous to those in RP La-cuprates, i.e., parent phases of the high-temperature superconducting oxides.
First-order equivalent to Einstein-Hilbert Lagrangian
Authors: López M. Castrillón , Masqué J. Muñoz , María E. Rosado
Published: July 2014

A first-order Lagrangian L∇ variationally equivalent to the second-order Einstein-Hilbert Lagrangian is introduced. Such a Lagrangian depends on a symmetric linear connection, but the dependence is covariant under diffeomorphisms. The variational problem defined by L∇ is proved to be regular and its Hamiltonian formulation is studied, including its covariant Hamiltonian attached to ∇.
Electromagnetic wave scattering by small perfectly conducting particles and applications
Authors: Ramm A. G.
Published: July 2014

A rigorous theory of electromagnetic wave scattering by one and many perfectly conducting small bodies of an arbitrary shape is developed. Equation for the effective field is derived in a medium in which many small particles are distributed. A method is given to change the refraction coefficient of a given medium in a desired direction by embedding into this medium many small particles.
Analytic matrix elements for the two-electron atomic basis with logarithmic terms
Authors: Liverts Evgeny Z. , Barnea Nir
Published: July 2014

The two-electron problem for the helium-like atoms in S-state is considered. The basis containing the integer powers of ln r, where r is a radial variable of the Fock expansion, is studied. In this basis, the analytic expressions for the matrix elements of the corresponding Hamiltonian are presented. These expressions include only elementary and special functions, what enables very fast and accurate computation of the matrix elements. The decisive contribution of the correct logarithmic terms to the behavior of the two-electron wave function in the vicinity of the triple-coalescence point is reaffirmed.
Charge-signal multiplication mediated by urea wires inside Y-shaped carbon nanotubes
Authors: Lv Mei , He Bing , Liu Zengrong , Xiu Peng , Tu Yusong
Published: July 2014

In previous studies, we reported molecular dynamics (MD) simulations showing that single-file water wires confined inside Y-shaped single-walled carbon nanotubes (Y-SWNTs) held strong and robust capability to convert and multiply charge signals [Y. S. Tu, P. Xiu, R. Z. Wan, J. Hu, R. H. Zhou, and H. P. Fang, Proc. Natl. Acad. Sci. U.S.A. 106, 18120 (2009); Y. Tu, H. Lu, Y. Zhang, T. Huynh, and R. Zhou, J. Chem. Phys. 138, 015104 (2013)]. It is fascinating to see whether the signal multiplication can be realized by other kinds of polar molecules with larger dipole moments (which make the experimental realization easier). In this article, we use MD simulations to study the urea-mediated signal conversion and multiplication with Y-SWNTs. We observe that when a Y-SWNT with an external charge of magnitude 1.0 e (the model of a signal at the single-electron level) is solvated in 1 M urea solutions, urea can induce drying of the Y-SWNT and fill its interiors in single-file, forming Y-shaped urea wires. The external charge can effectively control the dipole orientation of the urea wire inside the main channel (i.e., the signal can be readily converted), and this signal can further be multiplied into 2 (or more) output signals by modulating dipole orientations of urea wires in bifurcated branch channels of the Y-SWNT. This remarkable signal transduction capability arises from the strong dipole-induced ordering of urea wires under extreme confinement. We also discuss the advantage of urea as compared with water in the signal multiplication, as well as the robustness and biological implications of our findings. This study provides the possibility for multiplying signals by using urea molecules (or other polar organic molecules) with Y-shaped nanochannels and might also help understand the mechanism behind signal conduction in both physical and biological systems.
On the use of explicitly correlated treatment methods for the generation of accurate polyatomic –He/H2 interaction potential energy surfaces: The case of C3–He complex and generalization
Authors: Al Mogren M. M. , Denis-Alpizar O. , Abdallah D. Ben , Stoecklin T. , Halvick P. , Senent M.-L. , Hochlaf M.
Published: July 2014

Through the study of the C3(${\tilde X}$X̃1Σg+) + He(1S) astrophysical relevant system using standard (CCSD(T)) and explicitly correlated (CCSD(T)-F12) coupled cluster approaches, we show that the CCSD(T)-F12/aug-cc-pVTZ level represents a good compromise between accuracy and low computational cost for the generation of multi-dimensional potential energy surfaces (PESs) over both intra- and inter-monomer degrees of freedom. Indeed, the CCSD(T)-F12/aug-cc-pVTZ 2D-PES for linear C3 and the CCSD(T)-F12/aug-cc-pVTZ 4D-PES for bent C3 configurations gently approach those mapped at the CCSD(T)/aug-cc-pVXZ (X = T,Q) + bond functions level, whereas a strong reduction of computational effort is observed. After exact dynamical computations, the pattern of the rovibrational levels of the intermediate C3–He complex and the rotational and rovibrational (de-) excitation of C3 by He derived using both sets of PESs agree quite well. Since C3 shows a floppy character, the interaction PES is defined in four dimensions to obtain realistic collisional parameters. The C–C–C bending mode, which fundamental lies at 63 cm−1 and can be excited at very low temperatures is explicitly considered as independent coordinate. Our work suggests hence that CCSD(T)-F12/aug-cc-pVTZ methodology is the key method for the generation of accurate polyatomic – He/H2 multi-dimensional PESs.
Relevance of turbulence behind the single square grid to turbulence generated by regular- and multiscale-grids
Authors: Zhou Yi , Nagata Kouji , Sakai Yasuhiko , Suzuki Hiroki , Ito Yasumasa , Terashima Osamu , Hayase Toshiyuki
Published: July 2014

Direct numerical simulations were carried out to study the turbulence generated by a fractal square grid at a Reynolds number of \documentclass[12pt]{minimal}\begin{document}$Re_{L_0}$\end{document}ReL0 = 20000 (based on the inlet velocity Uin and length of the largest grid bar L0). We found that in the near-field region, the fractal square grid can generate much higher turbulence levels and has a better mixing performance than the single square grid. However, the current numerical results show that a single square grid can produce a turbulence intensity and turbulent Reynolds number at the end of the simulation region (i.e., X/L0 ≃ 13) comparable to those of a higher-blockage fractal square grid because the two turbulent flows have quite different energy decay rates. We also demonstrated that for the fractal square grid, the length L0 gives a physical description of the inlet Reynolds number. An examination of the characteristic length scale for the fractal square grid reveals that the unusual high energy decay rates in previous experiments [D. Hurst and J. C. Vassilicos, “Scalings and decay of fractal-generated turbulence,” Phys. Fluids 19, 035103 (2007); N. Mazellier and J. C. Vassilicos, “Turbulence without Richardson-Kolmogorov cascade,” Phys. Fluids 22, 075101 (2010)] are limited in the near-field (initial decay) region, although this region can last for many meters downstream of the fractal square grids after the production region. Simulation results suggest that the turbulence intensity and energy decay rate of the fractal-generated turbulence may go back to classical values in the region X > 13L0. Additional simulations demonstrate that the fractal square grid can be regarded as an efficient additional turbulence generator in the near-field and can increase turbulent mixing near the grid.
Fluid electron, gyrokinetic ion simulations of linear internal kink and energetic particle modes
Authors: Cole Michael , Mishchenko Alexey , Könies Axel , Kleiber Ralf , Borchardt Matthias
Published: July 2014

The internal kink mode is an important plasma instability responsible for a broad class of undesirable phenomena in tokamaks, including the sawtooth cycle and fishbones. To predict and discover ways to mitigate this behaviour in current and future devices, numerical simulations are necessary. The internal kink mode can be modelled by reduced magnetohydrodynamics (MHD). Fishbone modes are an inherently kinetic and non-linear phenomenon based on the n = 1 Energetic Particle Mode (EPM), and have been studied using hybrid codes that combine a reduced MHD bulk plasma model with a kinetic treatment of fast ions. In this work, linear simulations are presented using a hybrid model which couples a fluid treatment of electrons with a gyrokinetic treatment of both bulk and fast ions. Studies of the internal kink mode in geometry relevant to large tokamak experiments are presented and the effect of gyrokinetic ions is considered. Interaction of the kink with gyrokinetic fast ions is also considered, including the destabilisation of the linear n = 1 EPM underlying the fishbone.
An applied light-beam induced current study of dye-sensitised solar cells: Photocurrent uniformity mapping and true photoactive area evaluation
Authors: Jones Timothy W. , Feron Krishna , Anderson Kenrick F. , Duck Benjamin C. , Wilson Gregory J.
Published: July 2014

The conditions for light-beam induced current (LBIC) measurement were experimentally optimised for dye-sensitised solar cells. The impacts of too fast a laser diode modulation frequency (f) and too short a dwell time (t0) were investigated for their distortions, artefacts, and noise on the overall photocurrent map image. Optimised mapping conditions for fastest measurement were obtained at a f = 15 Hz and t0 = 900 ms. Whole device maps (nominal area 4 × 4 mm2) were obtained on devices in which fabrication defects were intentionally induced. The defects were readily resolved with the LBIC setup and conditions. The inclusion of defects had the effect of broadening the photocurrent distribution and producing a sub-optimal tail to photocurrent histograms. Photoactive areas were derived from LBIC maps and were larger than those predicted by the projected screen printing pattern by up to 25%, which has obvious implications for efficiency measurements made on nominal projected active area.