bluuebunny/crossref_metadata_2025 huggingface dataset:
CoRoute: a new cognitive anypath vehicular routing protocol
Authors: Kim Wooseong , Gerla Mario , Oh Soon Y. , Lee Kevin , Kassler Andreas
Published: November 2011

Vehicular communications promise to bring us safer driving and better traffic control. Dedicated short range communications and IEEE 802.11p are now well established standards for vehicular communications. Channels for those systems, however, are of limited capacity and are dedicated to safety applications. Thus, they are not sufficient to support the broad range of services envisioned in VANETs. It is anticipated that vehicles will utilize Wi‐Fi (802.11 a/b/g) to acquire more capacity. Unfortunately, the Wi‐Fi channels in urban areas are already quite heavily subscribed by residential customers. To evade the residential load, in this paper, we propose CoVanet, a cognitive vehicular ad hoc network architecture that allows vehicle radios to access the Wi‐Fi channels ‘opportunistically’, finding least loaded channels. In CoVanet, network topology and channel environment change frequently because of high node mobility. The main contribution of this work is a cognitive ad hoc vehicular routing protocol (CoRoute). CoRoute is a hybrid that utilizes both geographical location and sensed channel information to establish stable, minimum delay routes to the destination. Simulation results show that CoRoute is robust to mobility and to external interference and improves packet delivery ratio on average by 70% with respect to routing without cognitive radios. Copyright © 2011 John Wiley & Sons, Ltd.
Living‐donor liver transplantation for moderate or severe porto‐pulmonary hypertension accompanied by pulmonary arterial hypertension: a single‐centre experience over 2 decades in Japan
Authors: Ogawa Eri , Hori Tomohide , Doi Hiraku , Segawa Hajime , Uemoto Shinji
Published: November 2011

Background

Candidates for orthotopic liver transplantation (OLT) often have porto‐pulmonary hypertension (PPHTN) with pulmonary arterial hypertension (PAH). Poor outcomes of PPHTN contraindicate OLT. There are no guidelines for living‐donor liver transplantation (LDLT) in PPHTN patients.

Methods

We present our experiences of LDLT in six patients with moderate or severe PPHTN, along with our institutional guidelines. Three had liver cirrhosis and three were non‐cirrhotic. Catheterization studies were undertaken before, during and after LDLT, and the mean pulmonary arterial pressure (mPAP), cardiac output (CO), pulmonary vascular resistance and total peripheral resistance (TPR) were monitored.

Results

The results showed significant differences in CO and TPR between cirrhotic and non‐cirrhotic patients before, during and after LDLT. Cirrhotic patients showed systemic hyperdynamic state. Two cirrhotic patients showed poor responses to pre‐transplant treatment, and continued to have increased PAH and poor clinical courses after LDLT. LDLT has an advantage of flexible timing of LT. Currently in our institution, PPHTN patients with mPAP <40 mmHg are registered for LDLT after treatment and catheterization. However, LDLT is performed when mPAP is ⩽35 mmHg, leading to improved outcomes.

Conclusion

PPHTN patients with well‐controlled PAH, or secondary PAH resulting from porto‐systemic shunts, may be appropriate candidates for LDLT after careful considerations.
Pancreaticoduodenectomy for invasive pancreatic cancer (with video)
Authors: Takahashi Hidenori , Ohigashi Hiroaki , Ishikawa Osamu
Published: November 2011

Pancreaticoduodenectomy (PD) is the only treatment option that potentially provides a cure for pancreatic head cancer. Various arrangements and modifications have been proposed to achieve pathological margin negative (R0) resection safely. In this article, we introduce a standard procedure for PD, including pancreaticogastrostomy with invagination and mattress sutures (video clip provided), for invasive ductal carcinoma of the pancreatic head, with a description of the need‐to‐know pitfalls for Board‐certified HBP surgeons in Japan. The important points in performing PD for pancreatic cancer are: (1) While dissecting connective tissue and nerve plexus as well as lymph nodes, maintain a dissection plane to expose the surfaces of vessels or other organs to be preserved to achieve R0 resection: i.e., while dissecting the anterior surface of the inferior vena cava and the right side of the superior mesenteric artery, these vessels should be completely exposed with the connective tissue and nerve plexuses being attached to the resection side. (2) There should be early interruption of the afferent blood supply via the inferior pancreaticoduodenal artery to reduce blood loss by avoiding congestion of the pancreatic head and to increase the operative safety (video clip provided). (3) Eligibility for PD should be carefully evaluated because there are many “resectable” but not many “curable” cases. In addition, the clinical significance of various modifications of the surgical techniques used for PD are also discussed.
Middle pancreatectomy
Authors: Motoi Fuyuhiko , Egawa Shinichi , Unno Michiaki
Published: November 2011

Middle pancreatectomy is parenchyma‐ and adjacent organ‐sparing pancreatectomy indicated for small tumors located in the body, but deeply located in the gland, and therefore hard to enucleate. Others lesions including pancreatic trauma or arteriovenous malformation are also candidate targets. Invasive ductal carcinoma, even when the tumor is small enough, is not eligible because the most of these tumors show extrapancreatic invasion. After exposure of neck to body of the pancreas, middle pancreatectomy was performed by proximal and distal transection, reconstruction after Roux‐Y pancreaticojejunostomy, which is the most common. This procedure is low‐invasive and allow the preservation of exocrine and endocrine pancreatic function without loss of duodenal passage, however, it also has a high morbidity associated with pancreatic fistula. This article provides indications and surgical techniques with special focus on the procedure of middle pancreatectomy.
Things Fall Apart: Health Consequences of Mass Imprisonment for African American Women
Authors: Lee Hedwig , Wildeman Christopher
Published: November 2011

In this article, we examine the possible impact of mass imprisonment on the physical health of African American women. Specifically, we focus on a variety of mechanisms through which mass imprisonment may increase the risk of having three major chronic health conditions that are risk factors for cardiovascular disease (CVD): hypertension, diabetes, and obesity. This approach is distinctive in that it provides a broad theoretical framework through which mass imprisonment might harm the physical health of African American women in ways separate from the pathways linking mass imprisonment to their risk of contracting infectious diseases (especially HIV and other STIs), which has been the emphasis of most research in this area. In order to draw these connections, we begin by briefly discussing what mass imprisonment is and its social consequences. We then discuss our three CVD risk factors, documenting disparities between white and African American women in these risk factors and discussing mechanisms through which mass imprisonment might contribute to these disparities. We close by discussing the data needed to test our hypotheses and suggesting some avenues for future research.
HDACi: molecular mechanisms and therapeutic implications in the innate immune system
Authors: Suliman Bandar Ali , Xu Dakang , Williams Bryan RG
Published: November 2011

Histone deacetylase inhibitors (HDACi) are an emerging class of novel anti‐cancer drugs that cause growth arrest, differentiation and apoptosis of tumor cells. In addition, many advances have been made in understanding the immunoregulation of Toll‐like receptors, NOD‐like receptors and interferons that have recently generated new momentum for the study of HDACi in immunity as a whole, and in the regulation of these innate signaling pathways specifically. HDACi have shown promise as new anti‐inflammatory and immunosuppressant agents. They have also demonstrated great potency and relative selectivity in various human/animal models of inflammatory diseases. This review focuses on recent progress and the current state of HDACi knowledge, as well as the molecular mechanisms and therapeutic potential of HDACi for the treatment of inflammatory diseases and cancers.
HDAC inhibitors in HIV
Authors: Wightman Fiona , Ellenberg Paula , Churchill Melissa , Lewin Sharon R
Published: November 2011

Combination antiretroviral therapy (cART) has led to a very substantial reduction in morbidity and mortality in HIV‐infected patients; however, cART alone is unable to cure HIV and therapy is lifelong. Therefore, a new strategy to cure HIV is urgently needed. There is now a concerted effort from scientists, clinicians and funding agencies to identify ways to achieve either a functional cure (long‐term control of HIV in the absence of cART) or a sterilizing cure (elimination of all HIV‐infected cells). Multiple strategies aiming at achieving a cure for HIV are currently being investigated, including both pharmacotherapy and gene therapy. In this review, we will review the rationale as well as in vitro and clinical trial data that support the role of histone deacetylase inhibitors as one approach to cure HIV.
Arginase‐dependent suppression by CpG‐ODN plus IFA‐induced splenic myeloid CD11b+Gr1+ cells
Authors: Ranocchia Romina P , Gorlino Carolina V , Crespo María I , Harman María F , Liscovsky Miriam V , Morón Gabriel , Maletto Belkys A , Pistoresi‐Palencia María C
Published: November 2011

The ability of synthetic oligodeoxynucleotides containing unmethylated cytosine guanine motifs (CpG‐ODN) to induce both stimulatory and counter‐regulatory responses offers novel opportunities for using these molecules as immunomodulatory agents in different therapeutic strategies. Here, we investigated the potential of CpG‐ODN to activate the arginase (ARG) enzyme in vivo and focused on the consequences of this activation in T‐cell proliferation. Challenging mice subcutaneously with CpG‐ODN emulsified in incomplete Freund's adjuvant (IFA) induced ARG and reduced T‐cell proliferation associated with CD3ζ chain downregulation. Interestingly, impaired T‐cell expansion correlated with elevated levels of CD11b+Gr1+ myeloid cells localized near T‐cell areas in the spleen. In addition, purified CD11b+ cells obtained from the spleen of CpG‐ODN+IFA‐treated mice exhibited increased ARG activity and ARG I expression along with an augmented [3H]‐l‐arginine uptake. CD11b+ myeloid cells significantly suppressed T‐cell proliferation and CD3ζ chain expression induced by a polyclonal stimulus. Furthermore, these effects could be recovered by the addition of excess l‐arginine or by treatment of CD11b+ cells with a specific ARG inhibitor. This study provides a novel evidence that CpG‐ODN+IFA are able to induce splenic CD11b+ cells with ARG activity, with this population being responsible for the impaired T‐cell proliferation observed after the treatment with CpG‐ODN+IFA. These results underscore a key role of CpG‐ODN on ARG activity in vivo and add support to the growing body of evidence in favor of a counter‐regulatory role for CpG‐ODN in an immune response.
Lysine acetylation in obesity, diabetes and metabolic disease
Authors: Iyer Abishek , Fairlie David P , Brown Lindsay
Published: November 2011

Histone acetyltransferases (HATs) and histone deacetylases (HDACs) mediate acetylation and deacetylation of histone proteins and transcription factors. There is abundant evidence that these enzymes regulate the acetylation state of many cytoplasmic proteins, including lysine residues in important metabolic enzymes. Lysine acetylation regulates major cellular functions as a common post‐transcriptional modification of proteins, conserved from prokaryotes to humans. In this article, we refer to HATs and HDACs broadly as lysine acetyltransferases (KATs) and deacetylases (KDACs). Lysine acetylation is vitally important in both immunological and metabolic pathways and may regulate the balance between energy storage and expenditure. Obesity, type II diabetes and cardiovascular disease (metabolic syndrome) are widely recognised as features of a chronic low‐grade inflammatory state, involving significant alterations in primary immunometabolism. Identifying effective therapeutic and preventive options to treat this multi‐factorial syndrome has proven to be very challenging, with an emerging focus on developing anti‐inflammatory agents that can combat adiposity and metabolic disease. Here, we summarise current evidence and understanding of innate immune and metabolic pathways relevant to adiposity and metabolic disease regulated by lysine acetylation. Developing this understanding in greater detail may facilitate strategic development of novel and enzyme‐specific lysine deacetylase modulators that regulate both metabolic and immune systems.
First Report of 1 Micron Spatial Resolution Chemical Imaging of a Zirconium Single Crystal by FT-NIR Microspectroscopy
Authors: Baianu I.
Published: November 2011

This is the first report of 1 micron resolution chemical images of a Zirconium single crystal by FT-NIR Microspectroscopy. The FT-NIR spectra were obtained with a PerkinElmer SpectrumONE NTS spectrometer. The chemical images were obtained with a PerkinElmer Autoimage model FT-NIR microscope equipped with a very high sensitivity In /GaAs detector capable of precise measurements at ~10 ng, that was coupled to the SpectrumONE NTS FT-NIR spectrometer.
Structural properties of the noncommutative KdV recursion operator
Authors: Schiebold C.
Published: November 2011

The present work studies structural properties of the recursion operator of the noncommutative KdV equation. As the main result, it is proved that this operator is hereditary. The notion of hereditary operators was introduced by Fuchssteiner for infinite-dimensional integrable systems, building on classical concepts from differential topology. As an illustration for the consequences of this property, it is deduced that the flows of the noncommutative KdV hierarchy mutually commute.
Exponentially localized Wannier functions in periodic zero flux magnetic fields
Authors: De Nittis G. , Lein M.
Published: November 2011

In this work, we investigate conditions which ensure the existence of an exponentially localized Wannier basis for a given periodic hamiltonian. We extend previous results [Panati, G., Ann. Henri Poincare 8, 995–1011 (2007)10.1007/s00023-007-0326-8] to include periodic zero flux magnetic fields which is the setting also investigated by Kuchment [J. Phys. A: Math. Theor. 42, 025203 (2009)10.1088/1751-8113/42/2/025203]. The new notion of magnetic symmetry plays a crucial rôle; to a large class of symmetries for a non-magnetic system, one can associate “magnetic” symmetries of the related magnetic system. Observing that the existence of an exponentially localized Wannier basis is equivalent to the triviality of the so-called Bloch bundle, a rank m hermitian vector bundle over the Brillouin zone, we prove that magnetic time-reversal symmetry is sufficient to ensure the triviality of the Bloch bundle in spatial dimension d = 1, 2, 3. For d = 4, an exponentially localized Wannier basis exists provided that the trace per unit volume of a suitable function of the Fermi projection vanishes. For d > 4 and d ⩽ 2m (stable rank regime) only the exponential localization of a subset of Wannier functions is shown; this improves part of the analysis of Kuchment [J. Phys. A: Math. Theor. 42, 025203 (2009)10.1088/1751-8113/42/2/025203]. Finally, for d > 4 and d > 2m (unstable rank regime) we show that the mere analysis of Chern classes does not suffice in order to prove triviality and thus exponential localization.
Combined visible light photo-emission and low temperature thermionic emission from nitrogen doped diamond films
Authors: Sun Tianyin , Koeck Franz A. M. , Zhu Chiyu , Nemanich Robert J.
Published: November 2011

This study reports a photoemission threshold of ∼1.5 eV from nitrogen-doped nanocrystalline diamond, which ranks among the lowest photo-threshold of any non-cesiated material. Diamond films on molybdenum substrates have been illuminated with light from 340 to 550 nm, and the electron emission spectrum has been recorded from ambient to ∼320 °C. The results display combined thermionic and photo-electron emission limited by the same low work function and indicate that the two emission processes are spatially separated. These results indicate the potential for a solar energy conversion structure that takes advantage of both photoemission and thermionic emission.
Development of an alpha/beta/gamma detector for radiation monitoring
Authors: Yamamoto Seiichi , Hatazawa Jun
Published: November 2011

For radiation monitoring at the site of nuclear power plant accidents such as Fukushima Daiichi, radiation detectors not only for gamma photons but also for alpha and beta particles are needed because some nuclear fission products emit beta particles and gamma photons and some nuclear fuels contain plutonium that emits alpha particles. We developed a radiation detector that can simultaneously monitor alpha and beta particles and gamma photons for radiation monitoring. The detector consists of three-layered scintillators optically coupled to each other and coupled to a photomultiplier tube. The first layer, which is made of a thin plastic scintillator (decay time: 2.4 ns), detects alpha particles. The second layer, which is made of a thin Gd2SiO5 (GSO) scintillator with 1.5 mol.% Ce (decay time: 35 ns), detects beta particles. The third layer made of a thin GSO scintillator with 0.4 mol.% Ce (decay time: 70 ns) detects gamma photons. By using pulse shape discrimination, the count rates of these layers can be separated. With individual irradiation of alpha and beta particles and gamma photons, the count rate of the first layer represented the alpha particles, the second layer represented the beta particles, and the third layer represented the gamma photons. Even with simultaneous irradiation of the alpha and beta particles and the gamma photons, these three types of radiation can be individually monitored using correction for the gamma detection efficiency of the second and third layers. Our developed alpha, beta, and gamma detector is simple and will be useful for radiation monitoring, especially at nuclear power plant accident sites or other applications where the simultaneous measurements of alpha and beta particles and gamma photons are required.
Ice particles trapped by temperature gradients at mbar pressure
Authors: Kelling Thorben , Wurm Gerhard , Dürmann Christoph
Published: November 2011

In laboratory experiments we observe that ice particles (⩽100 μm) entrained in a low pressure atmosphere (∼1 mbar) get trapped by temperature gradients between three reservoirs at different temperature. Confining elements are a peltier element at 250 K (bottom), a liquid nitrogen reservoir at 77 K (top), and the surrounding vacuum chamber at 293 K. Particle levitation and trapping is modeled by an interplay of thermophoresis, photophoresis, and gravity. A number of ice particles are trapped simultaneously in close spatial distance to each other at least up to minutes and are accessible for further experiments.
Photoelectron spectroscopy of higher bromine and iodine oxide anions: Electron affinities and electronic structures of BrO2,3 and IO2–4 radicals
Authors: Wen Hui , Hou Gao-Lei , Huang Wei , Govind Niranjan , Wang Xue-Bin
Published: November 2011

This report details a photoelectron spectroscopy (PES) and theoretical investigation of electron affinities (EAs) and electronic structures of several atmospherically relevant higher bromine and iodine oxide molecules in the gas phase. PES spectra of BrO2− and IO2− were recorded at 12 K and four photon energies—355 nm/3.496 eV, 266 nm/4.661 eV, 193 nm/6.424 eV, and 157 nm/7.867 eV—while BrO3−, IO3−, and IO4− were only studied at 193 and 157 nm due to their expected high electron binding energies. Spectral features corresponding to transitions from the anionic ground state to the ground and excited states of the neutral are unraveled and resolved for each species. The EAs of these bromine and iodine oxides are experimentally determined for the first time (except for IO2) to be 2.515 ± 0.010 (BrO2), 2.575 ± 0.010 (IO2), 4.60 ± 0.05 (BrO3), 4.70 ± 0.05 (IO3), and 6.05 ± 0.05 eV (IO4). Three low-lying excited states along with their respective excitation energies are obtained for BrO2 [1.69 (A 2B2), 1.79 (B 2A1), 1.99 eV (C 2A2)], BrO3 [0.7 (A 2A2), 1.6 (B 2E), 3.1 eV (C 2E)], and IO3 [0.60 (A 2A2), 1.20 (B 2E), ∼3.0 eV (C 2E)], whereas six excited states of IO2 are determined along with their respective excitation energies of 1.63 (A 2B2), 1.73 (B 2A1), 1.83 (C 2A2), 4.23 (D 2A1), 4.63 (E 2B2), and 5.23 eV (F 2B1). Periodate (IO4−) possesses a very high electron binding energy. Only one excited state feature with 0.95 eV excitation energy is shown in the 157 nm spectrum. Accompanying theoretical calculations reveal structural changes from the anions to the neutrals, and the calculated EAs are in good agreement with experimentally determined values. Franck-Condon factors simulations nicely reproduce the observed vibrational progressions for BrO2 and IO2. The low-lying excited state information is compared with theoretical calculations and discussed with their atmospheric implications.
Self-focusing of intense high frequency electromagnetic waves in a collisional magnetoactive plasma
Authors: Niknam A. R. , Aliakbari A. , Majedi S. , Haji Mirzaei F. , Hashemzadeh M.
Published: November 2011

The self-focusing of an intense electromagnetic beam in a collisional magnetoactive plasma has been investigated by the perturbation method. Considering the relativistic and ponderomotive nonlinearities and the first three terms of perturbation expansion for the electron density and velocity, the nonlinear wave equation is obtained. This wave equation is solved by applying the source dependent expansion method and the evolution of electromagnetic beam spot-size is discussed. It is shown that the laser spot-size decreases with increasing the collision frequency and external magnetic field strength.
Analytical approach for the excited-state Hessian in time-dependent density functional theory: Formalism, implementation, and performance
Authors: Liu Jie , Liang WanZhen
Published: November 2011

The paper presents the formalism, implementation, and performance of the analytical approach for the excited-state Hessian in the time-dependent density functional theory (TDDFT) that extends our previous work [J. Liu and W. Z. Liang, J. Chem. Phys. 135, 014113 (2011)] on the analytical Hessian in TDDFT within Tamm-Dancoff approximation (TDA) to full TDDFT. In contrast to TDA-TDDFT, an appreciable advantage of full TDDFT is that it maintains the oscillator strength sum rule, and therefore yields more precise results for the oscillator strength and other related physical quantities. For the excited-state harmonic vibrational frequency calculation, however, full TDDFT does not seem to be advantageous since the numerical tests demonstrate that the accuracy of TDDFT with and without TDA are comparable to each other. As a common practice, the computed harmonic vibrational frequencies are scaled by a suitable scale factor to yield good agreement with the experimental fundamental frequencies. Here we apply both the optimized ground-state and excited-state scale factors to scale the calculated excited-state harmonic frequencies and find that the scaling decreases the root-mean-square errors. The optimized scale factors derived from the excited-state calculations are slightly smaller than those from the ground-state calculations.
Propagation of solitary waves in relativistic electron-positron-ion plasmas with kappa distributed electrons and positrons
Authors: Shah Asif , Mahmood S. , Haque Q.
Published: November 2011

Electrostatic ion acoustic solitary waves are studied in a plasma system comprising of relativistic ions, kappa distributed electrons, and positrons. The increase in the relativistic streaming factor and positron and electron kappa parameters cause the soliton amplitude to thrive. However, the soliton amplitude diminishes as the positron concentration is increased in the system. Our results are general and may be helpful, in understanding nonlinear phenomena in the presence of kappa distibuted electrons, positrons, and relativistically streaming ions.
Growth-in-place deployment of in-plane silicon nanowires
Authors: Yu Linwei , Chen Wanghua , O’Donnell Benedict , Patriarche Gilles , Bouchoule Sophie , Pareige Philippe , Rogel Regis , Claire Salaun Anne , Pichon Laurent , Roca i Cabarrocas Pere
Published: November 2011

Up-scaling silicon nanowire (SiNW)-based functionalities requires a reliable strategy to precisely position and integrate individual nanowires. We here propose an all-in-situ approach to fabricate self-positioned/aligned SiNW, via an in-plane solid-liquid-solid growth mode. Prototype field effect transistors, fabricated out of in-plane SiNWs using a simple bottom-gate configuration, demonstrate a hole mobility of 228 cm2/V s and on/off ratio >103. Further insight into the intrinsic doping and structural properties of these structures was obtained by laser-assisted 3 dimensional atom probe tomography and high resolution transmission electron microscopy characterizations. The results could provide a solid basis to deploy the SiNW functionalities in a cost-effective way.
Thin layer thickness measurements by zero group velocity Lamb mode resonances
Authors: Cès Maximin , Clorennec Dominique , Royer Daniel , Prada Claire
Published: November 2011

Local and non-contact measurements of the thickness of thin layers deposited on a thick plate have been performed by using zero group velocity (ZGV) Lamb modes. It was shown that the shift of the resonance frequency is proportional to the mass loading through a factor which depends on the mechanical properties of the layer and of the substrate. In the experiments, ZGV Lamb modes were generated by a Nd:YAG pulsed laser and the displacement normal to the plate surface was measured by an optical interferometer. Measurements performed at the same point that the generation on the non-coated face of the plate demonstrated that thin gold layers of a few hundred nanometers were detected through a 1.5-mm thick Duralumin plate. The shift of the resonance frequency (1.9 MHz) of the fundamental ZGV mode is proportional to the layer thickness: typically 10 kHz per μm. Taking into account the influence of the temperature, a 240-nm gold layer was measured with a ±4% uncertainty. This thickness has been verified on the coated face with an optical profiling system.
Invariants, projection operators and SU(N)×SU(N) irreducible Schwinger bosons
Authors: Mathur Manu , Raychowdhury Indrakshi , Sreeraj T P
Published: November 2011

We exploit SU(N) Schwinger bosons to construct and analyze the coupled irreducible representations of SU(N) × SU(N) in terms of the invariant group. The corresponding projection operators are constructed in terms of the invariant group generators. We also construct SU(N) × SU(N) irreducible Schwinger bosons which directly create these coupled irreducible states. The SU(N) Clebsch-Gordan coefficients are computed as the matrix elements of the projection operators.
A tiered approach to Monte Carlo sampling with self-consistent field potentials
Authors: Steele Ryan P. , Tully John C.
Published: November 2011

A “tiered” approach to Monte Carlo sampling of nuclear configurations is presented for ab initio, self-consistent field (SCF)-based potentials, including Hartree-Fock and density functional theory. Rather than Metropolis testing only the final SCF energy, individual cycle energies are tested in a tiered fashion, without approximation. Accordingly, rejected configurations are terminated early in the SCF procedure. The method is shown to properly obey detailed balance, and effective modifications are presented for cases in which the initial SCF guess is particularly poor. Demonstrations on simple systems are provided, including an assessment of the thermal properties of the neutral water dimer with B3LYP/6-31++G**. Cost analysis indicates a factor-of-two reduction in SCF cycles, which makes the method competitive with accelerated molecular dynamics sampling techniques, without the need for forces.
Magnetic exchange couplings from constrained density functional theory: An efficient approach utilizing analytic derivatives
Authors: Phillips Jordan J. , Peralta Juan E.
Published: November 2011

We introduce a method for evaluating magnetic exchange couplings based on the constrained density functional theory (C-DFT) approach of Rudra, Wu, and Van Voorhis [J. Chem. Phys. 124, 024103 (2006)10.1063/1.2145878]. Our method shares the same physical principles as C-DFT but makes use of the fact that the electronic energy changes quadratically and bilinearly with respect to the constraints in the range of interest. This allows us to use coupled perturbed Kohn-Sham spin density functional theory to determine approximately the corrections to the energy of the different spin configurations and construct a priori the relevant energy-landscapes obtained by constrained spin density functional theory. We assess this methodology in a set of binuclear transition-metal complexes and show that it reproduces very closely the results of C-DFT. This demonstrates a proof-of-concept for this method as a potential tool for studying a number of other molecular phenomena. Additionally, routes to improving upon the limitations of this method are discussed.
Lowest-energy structures and electronic properties of Na-Si binary clusters from ab initio global search
Authors: Sai Linwei , Tang Lingli , Zhao Jijun , Wang Jun , Kumar Vijay
Published: November 2011

The ground state structures of neutral and anionic clusters of NanSim (1 ≤ n ≤ 3, 1 ≤ m ≤ 11) have been determined using genetic algorithm incorporated in first principles total energy code. The size dependence of the structural and electronic properties is discussed in detail. It is found that the lowest-energy structures of NanSim clusters resemble those of the pure Si clusters. Interestingly, Na atoms in neutral NanSim clusters are usually well separated by the Sim skeleton, whereas Na atoms can form Na-Na bonds in some anionic clusters. The ionization potentials, adiabatic electron affinities, and photoelectron spectra are also calculated and the results compare well with the experimental data.
Generating extra long arcs using exploding wires
Authors: Sinton Rowan , van Herel Ryan , Enright Wade , Bodger Pat
Published: November 2011

Long electrical arcs that are created using high voltage impulses in air gaps require average electric fields (AEFs) in the order of 100 to 1000 kV/m. In this paper, a method is presented where arcs can be created using AEFs of just 4.5 kV/m. The results from experiments up to 60 m long are used to form a mathematical model that predicts the occurrence of arc formation. The parameters of the energy supply, namely the voltage and capacitance, are found to determine the length of the arc that can be obtained. This model can be used by other research groups to reliably create long arcs; it is shown that many high voltage laboratories already have equipment capable of producing arcs several hundred meters long by using this method.
A simple method for direct observation of the converse magnetoelectric effect in magnetic/ferroelectric composite thin films
Authors: Li Zheng , Hu Jiamian , Shu Li , Zhang Yi , Gao Ya , Shen Yang , Lin Yuanhua , Nan C. W.
Published: November 2011

A novel characterization method is presented to directly observe the pure converse magnetoelectric (ME) effect, i.e., the electric-field modification of magnetization, in composite magnetic/ferroelectric (FE) layered thin films. A low-frequency AC electric-voltage, rather than DC voltage bias, is applied to the FE thin films to minimize the leakage current, whereby the possible side effect of heating can be avoided. In particular, by synchronizing the frequency of the Kerr signal detector to the AC actuation voltage bias, the voltage-induced change of the magnetization in the magnetic films can be in situ recorded even under zero external magnetic fields. For illustration, this method is applied to two similar magnetic/FE composite thin films, with significant strain-mediated converse ME coupling being demonstrated in both cases.
Ozone generation by rock fracture: Earthquake early warning?
Authors: Baragiola Raúl A. , Dukes Catherine A. , Hedges Dawn
Published: November 2011

We report the production of up to 10 ppm ozone during crushing and grinding of typical terrestrial crust rocks in air, O2 and CO2 at atmospheric pressure, but not in helium or nitrogen. Ozone is formed by exoelectrons emitted by high electric fields, resulting from charge separation during fracture. The results suggest that ground level ozone produced by rock fracture, besides its potential health hazard, can be used for early warning in earthquakes and other catastrophes, such as landslides or land shifts in excavation tunnels and underground mines.
Bismuth-induced ferroelectric relaxor behavior in paraelectric LaAlO3
Authors: Si Mei-Ju , Hou Yu-Dong , Ge Hai-Yan , Zhu Man-Kang , Yan Hui
Published: November 2011

Perovskite-type dense ceramics (La0.9Bi0.1)AlO3 (LBAO) have been prepared through a solid-state reaction route. LaAlO3 is indeed a paraelectric, whereas a significant ferroelectric relaxor behavior is obtained in LBAO. The variations of ferroelectric hysteresis loops versus the applied field or frequency indicate the nature of the ferroelectric domain switching. A broad dielectric anomaly coupled with the shift in dielectric maxima toward a higher temperature with increasing frequency has been observed in LBAO, and the indicator of degree of diffuseness γ is about 1.86. Moreover, the dielectric relaxation, which follows the Vogel–Fulcher relationship with TVF = 706.9 K, f0 = 1.85 × 109 Hz, and Ea = 0.09 eV, further supports spin-glass-like characteristics. Compared with LaAlO3, the abnormal contraction of crystal cell is observed in LBAO, which does not follow the normal Vegard’s law. This can be attributed to the covalent hybridization of the Bi3+ ions with the surrounding O2- ions. The large local displacements at the off-centered Bi position lead to the formation of polarized nanoclusters in the paraelectric matrix and the reorientation of these unstable polarized nanoclusters further results in ferroelectric relaxor behavior.
Wire-bar coating of semiconducting polythiophene/insulating polyethylene blend thin films for organic transistors
Authors: Murphy Craig E. , Yang Li , Ray Santanu , Yu Liyang , Knox Steven , Stingelin Natalie
Published: November 2011

Organic blend thin films consisting of semiconducting poly(3-hexylthiophene) (P3HT) and insulating high-density polyethylene (HDPE) have been fabricated by novel application of a large area wire-bar coating technique in air. The microstructure of P3HT:HDPE blend films reveals a strong structural dependence on initial composition. Preferential segregation of P3HT toward the film surface is observed for all blend compositions, while P3HT (or P3HT-rich) columnar structures enclosed by HDPE (or HDPE-rich) lamellar matrix is distinctive for 50:50 (by weight) blends. The transistors fabricated with P3HT:HDPE blend films show a clear field effect behavior, exhibiting charge carrier mobilities up to 5 × 10−2 cm2/Vs, comparable to the values reported in spin-coated similar blends and of neat P3HT devices. The wire-bar coated blend films and devices are highly repeatable and spatially uniform over large areas (few cm by few cm), demonstrating the suitability of this technique for manufacturing of large area organic electronic devices.
Photonic bandstructure engineering of THz quantum-cascade lasers
Authors: Benz A. , Brandstetter M. , Deutsch C. , Unterrainer K. , Detz H. , Andrews A. M. , Klang P. , Schrenk W. , Strasser G.
Published: November 2011

We present the design and realization of active photonic crystal (PhC) terahertz (THz) lasers operating in higher photonic bands. The structure consists of an array of isolated pillars fabricated from a THz quantum-cascade laser and embedded in a double-metal waveguide. The PhC geometry is adopted to achieve lasing in the first and second photonic bands. Thereby, the optical mode is pushed from the active pillars into the surrounding. The sensitivity of local sensors can be increased by almost one order of magnitude compared to designs operating in the lowest photonic band.
Large oscillatory forces generated by interfacial water under lateral modulation between two hydrophilic surfaces
Authors: Kim Byung I. , Rasmussen Jared A. , Kim Edward J.
Published: November 2011

We observed remarkable oscillatory forces with amplitude of 60-90 nN and periodicity of 3–4 water molecule diameters in an ambient environment between two silicon surfaces as the tip-sample distance decreased using the cantilever-based optical interfacial force microscope with lateral modulation. As the humidity increased, the oscillatory forces changed from being large at lower relative humidities, below 40%, to progressively becoming smaller as the humidity went higher than 40%. The frequency of oscillatory forces increased with the existence of lateral tip-modulation and with the slower approaching tip-speed. Its starting point distance has been found to originate from the topographic water structure.
Diameter reduction of nanowire tunnel heterojunctions using in situ annealing
Authors: Mattias Borg B. , Ek Martin , Dick Kimberly A. , Ganjipour Bahram , Dey Anil W. , Thelander Claes , Wernersson Lars-Erik
Published: November 2011

We selectively etch axial GaSb/InAsSb nanowires locally at the heterojunction using in situ thermal annealing. This results in broken-gap tunnel diodes with a significantly reduced diameter only in the tunnel region. The etching mechanism proceeds by material removal from unstabilized {111}A facets which may form due to a reduced thermal stability at the heterointerface of GaSb/InAsSb nanowires. By removing the parallel conduction path between the InAsSb shell and nanowire the selective etching strongly improves the device performance. This is demonstrated in fabricated tunnel diodes that exhibit a peak-to-valley ratio of 1.3 and high peak current densities (8.1 kA/cm2).
Ion implantation synthesized copper oxide-based resistive memory devices
Authors: Bishop S. M. , Bakhru H. , Novak S. W. , Briggs B. D. , Matyi R. J. , Cady N. C.
Published: November 2011

Copper oxide resistive memory layers have been synthesized by ion implantation. Devices fabricated from off-stoichiometric Cu2O exhibited unipolar switching in forward/reverse bias without a forming voltage. The on-state conduction of these devices is likely dominated by a metallic filament, which ruptures via Joule heating to transition the device to the high resistance off-state. Technology scaling was achieved by oxygen implanting copper filled vias. The resulting via-based memory devices exhibited unipolar resistive switching down to 48 nm in diameter.
Long intersubband relaxation times in n-type germanium quantum wells
Authors: Ortolani Michele , Stehr Dominik , Wagner Martin , Helm Manfred , Pizzi Giovanni , Virgilio Michele , Grosso Giuseppe , Capellini Giovanni , De Seta Monica
Published: November 2011

We measured the non-radiative intersubband relaxation time in n-type modulation-doped Ge/SiGe multi-quantum wells of different thickness by means of degenerate pump-probe experiments. The photon energy was tuned to be resonant with the lowest conduction band intersubband transition energy (14-29 meV), as measured by terahertz absorption spectroscopy and in agreement with band structure calculations. Temperature-independent lifetimes in excess of 30 ps were observed.
Full correspondence between asymmetric filling of slits and first-order phase transition lines
Authors: Szybisz Leszek , Sartarelli Salvador A.
Published: November 2011

Adsorption on single planar walls and filling of slits with identical planar walls are investigated in the frame of the density functional theory. In this sort of slits the external potential is symmetric with respect to its central plane. Calculations were carried out by applying both the canonical and grand canonical ensembles (CE and GCE, respectively). The behavior is analyzed by varying the strength of the adsorbate-substrate attraction, the temperature T, and the coverage Γℓ. Results obtained for physisorption of Xe on alkaline surfaces are reported in the present work. Prewetting (PW) lines and wetting temperatures, Tw, are determined from the analysis of adsorption on single walls. The filling of slits is analyzed for temperatures T > Tw. It is found that whenever for a given Xe-substrate combination the adsorption on a single wall exhibits a first-order wetting transition then asymmetric profiles that break the left-right symmetry of the external potential appear in the filling of an equivalent slit. These spontaneously symmetry breaking (SSB) solutions occur in a restricted range of Γℓ with a T-dependent width. In the case of closed slits analyzed in the CE scheme, the obtained asymmetric profiles exhibit lower Helmholtz free energies than the symmetric species and, therefore, could be stabilized in this geometry. For open slits, the GCE scheme yields all the symmetric and SSB states in the corresponding convex regimes of the free energy. It is shown that both the CE and the GCE frames yield three coexistent states, two symmetric and one asymmetric twofold degenerate. Both a PW line and the related SSB effect terminate at the same temperature. For rather strongly attractive surfaces reentrant SSB states are found at a fixed value of T.
Photochemical reactions of methyl and ethyl nitrate: a dual role for alkyl nitrates in the nitrogen cycle
Authors: He Shuzhong , Chen Zhongming , Zhang Xuan
Published: November 2011

Environmental contextAlkyl nitrates are considered to be important intermediates in the atmospheric hydrocarbons–nitrogen oxides–ozone cycle, which significantly determines air quality and nitrogen exchange between the atmosphere and the Earth’s surfaces. The present laboratory study investigates reaction products of alkyl nitrates to elucidate their photochemical reaction mechanisms in the atmosphere. The results provide a better understanding of the role played by alkyl nitrates in the atmospheric environment.
AbstractAlkyl nitrates (ANs) are important nitrogen-containing organic compounds and are usually considered to be temporary reservoirs of reactive nitrogen NOx (NO2 and NO) in the atmosphere, although their atmospheric fates are incompletely understood. Here a laboratory study of the gas-phase photolysis and OH-initiated reactions of methyl nitrate (CH3ONO2) and ethyl nitrate (C2H5ONO2), as models of atmospheric ANs, is reported with a focus on elucidating the detailed photochemical reaction mechanisms of ANs in the atmosphere. A series of intermediate and end products were well characterised for the first time from the photochemical reactions of methyl and ethyl nitrate conducted under simulated atmospheric conditions. Notably, for both the photolysis and OH-initiated reactions of CH3ONO2 and C2H5ONO2, unexpectedly high yields of HNO3 (photochemically non-reactive nitrogen) were found and also unexpectedly high yields of peroxyacyl nitrates (RC(O)OONO2, where R = H, CH3, CH3CH2,…) (reactive nitrogen) have been found as CH3C(O)OONO2 in the C2H5ONO2 reaction or proposed as HC(O)OONO2 in the CH3ONO2 reaction. Although the yields of HNO3 from the ANs under ambient conditions are likely variable and different from those obtained in the laboratory experiments reported here, the results imply that the ANs could potentially serve as a sink for reactive nitrogen in the atmosphere. The potential for this dual role of organic nitrates in the nitrogen cycle should be considered in the study of air quality and nitrogen exchange between the atmosphere and surface. Finally, an attempt was made to estimate the production of HNO3 and peroxyacyl nitrates derived from NOx by ANs as intermediates in the atmosphere.
Diastereoisomer- and enantiomer-specific profiles of hexabromocyclododecane in the sediment of Dongjiang River, South China
Authors: Zhang Xian , Zhang Dandan , Luo Zhuanxi , Lin Lifeng , Yan Changzhou
Published: November 2011

Environmental contextHexabromocyclododecanes are widely used as additive brominated flame retardants in thermal insulation building materials, upholstery textiles and electronic products. Dongjiang River is located at the Pearl River Delta, one of the most highly industrialised regions in China, which was seriously polluted by hexabromocyclododecanes. Higher levels of hexabromocyclododecanes in Dongjiang River will pose a serious threat to ecological health in this region. AbstractThe objective of this study was to investigate the levels, diastereoisomer profiles and enantiomeric fractions of hexabromocyclododecanes (HBCDs) in the sediment of the Dongjiang River, China. The results showed that the total HBCD concentrations in the sediment ranged from below 2.5 to 424.16 ng g–1, which is similar to levels downstream of point source discharges in Europe and significantly higher than HBCD levels in sediments from rivers in the USA. The diastereoisomeric pattern showed the predominance of the γ-isomer, with low contributions of the α- and β-isomers. This diastereoisomer profile of the HBCDs was similar to that of commercial formulations. No uniform enantioselective enrichment was observed for α- and β-HBCD in sediments, which suggested that different stereoselective biotransformations occurred for these two isomers at different sites. However, (–)-γ-HBCD was apparently enriched in the sediment, which suggested that HBCDs in these studied sites were selectively biodegraded by microorganisms in the sediment.
Dementia information for culturally and linguistically diverse communities: sources, access and considerations for effective practice
Authors: Boughtwood Desiree , Shanley Christopher , Adams Jon , Santalucia Yvonne , Kyriazopoulos Helena , Pond Dimity , Rowland Jeffrey
Published: November 2011

Providing information about dementia has been shown to produce immense benefits for people living with dementia and their carers. The dementia information needs of culturally and linguistically diverse (CALD) families have not been comprehensively investigated. Addressing this research gap, the current study examines the perspectives of a range of stakeholders – CALD family caregivers (Arabic, Chinese, Italian and Spanish speaking), bilingual and bicultural workers, bilingual general practitioners and geriatricians – about dementia-related information. The study focussed on sources of information, issues of access and considerations for improving information provision. The main findings that are relevant for improving policy and practice are: the need for a more strategic and coordinated approach to dissemination structures and processes, a greater emphasis on supporting and enhancing the interpersonal aspects of information provision, the need for a greater range of information for CALD communities and the need to ensure information resources and processes reflect the circumstances and needs of these communities.