bluuebunny/crossref_metadata_2025 huggingface dataset:
Local structure of the B-site in BNT-xBT investigated by 47,49Ti NMR: Effect of barium content
Authors: Groszewicz Pedro B. , Breitzke Hergen , Jo Wook , Rödel Jürgen , Buntkowsky Gerd
Published: March 2017

Towards a deeper understanding of the local structure of the B-site in (100-x)(Bi1/2Na1/2)TiO3-xBaTiO3 (BNT-xBT) with 0 ≤ x ≤ 15, solid-state nuclear magnetic resonance (NMR) spectra of the titanium isotopes 47Ti and 49Ti were investigated. The 47,49Ti NMR spectra of BNT-xBT indicate a disordered local structure for the B-site of these perovskites. The line-shape of the titanium NMR spectra of BNT-xBT samples is found to be independent on the barium content. This fact implies that the local structure of the B-site remains invariant with respect to the structural changes that result from the chemical modification with barium. The analysis of 47,49Ti NMR spectra supports the hypothesis that the main structural changes across the morphotropic phase boundary in these solid-solutions are constrained to the A-site and are related to the tilting of rigid oxygen octahedra.
Spin dynamics of ZnSe-ZnTe nanostructures grown by migration enhanced molecular beam epitaxy
Authors: Deligiannakis Vasilios , Dhomkar Siddharth , Ji Haojie , Pagliero Daniela , Kuskovsky Igor L. , Meriles Carlos A. , Tamargo Maria C.
Published: March 2017

We study the spin dynamics of ZnSe layers with embedded type-II ZnTe quantum dots using time resolved Kerr rotation (TRKR). Three samples were grown with an increasing amount of Te, which correlates with increased quantum dot (QD) density. Samples with a higher quantum dot density exhibit longer electron spin lifetimes, up to ∼1 ns at low temperatures. Tellurium isoelectronic centers, which form in the ZnSe spacer regions as a result of the growth conditions, were probed via spectrally dependent TRKR. Temperature dependent TRKR results show that samples with high QD density are not affected by an electron-hole exchange dephasing mechanism.
Pretty good state transfer in qubit chains—The Heisenberg Hamiltonian
Authors: Banchi Leonardo , Coutinho Gabriel , Godsil Chris , Severini Simone
Published: March 2017

Pretty good state transfer in networks of qubits occurs when a continuous-time quantum walk allows the transmission of a qubit state from one node of the network to another, with fidelity arbitrarily close to 1. We prove that in a Heisenberg chain with n qubits, there is pretty good state transfer between the nodes at the jth and (n − j + 1)th positions if n is a power of 2. Moreover, this condition is also necessary for j = 1. We obtain this result by applying a theorem due to Kronecker about Diophantine approximations, together with techniques from algebraic graph theory.
Thermal conductance of graphene/hexagonal boron nitride heterostructures
Authors: Lu Simon , McGaughey Alan J. H.
Published: March 2017

The lattice-based scattering boundary method is applied to compute the phonon mode-resolved transmission coefficients and thermal conductances of in-plane heterostructures built from graphene and hexagonal boron nitride (hBN). The thermal conductance of all structures is dominated by acoustic phonon modes near the Brillouin zone center that have high group velocity, population, and transmission coefficient. Out-of-plane modes make their most significant contributions at low frequencies, whereas in-plane modes contribute across the frequency spectrum. Finite-length superlattice junctions between graphene and hBN leads have a lower thermal conductance than comparable junctions between two graphene leads due to lack of transmission in the hBN phonon bandgap. The thermal conductances of bilayer systems differ by less than 10% from their single-layer counterparts on a per area basis, in contrast to the strong thermal conductivity reduction when moving from single- to multi-layer graphene.
The effect of acoustically levitated objects on the dynamics of ultrasonic actuators
Authors: Ilssar D. , Bucher I.
Published: March 2017

This paper presents a comprehensive model, coupling a piezoelectric actuator operating at ultrasonic frequencies to a near-field acoustically levitated object through a compressible thin layer of gas such that the combined dynamic response of the system can be predicted. The latter is derived by introducing a simplified model of the nonlinear squeezed layer of gas and a variational model of the solid structure and the piezoelectric elements. Since the harmonic forces applied by the entrapped fluid depend on the levitated object's height and vertical motion, the latter affects the impedance of the driving surface, affecting the natural frequencies, damping ratios, and amplification of the actuator. Thus, the developed model is helpful when devising a resonance tracking algorithm aimed to excite a near-field acoustic levitation based apparatus optimally. Validation of the suggested model was carried out using a focused experimental setup geared to eliminate the effects that were already verified in the past. In agreement with the model, the experimental results showed that the natural frequency and damping ratio of a designated mode decrease monotonically with the levitated object's average height, whereas the amplification of the mode increases with the levitation height.
Near-infrared emission and optical temperature sensing performance of Nd3+:SrF2 crystal powder prepared by combustion synthesis
Authors: Rakov Nikifor , Maciel Glauco S.
Published: March 2017

Nd3+:SrF2 crystal powder prepared by combustion synthesis technique was analyzed for potential use in thermal sensing of biological systems. Near-infrared emission was observed under CW laser excitation at 532 nm. The near-infrared fluorescence spectrum consisting of two emission bands, corresponding to the 4F5/2 →4I9/2 and 4F3/2 →4I9/2 transitions, was recorded over a temperature range of 298–573 K. A noticeable change on the relative intensities of those transitions with temperature was observed as a consequence of the thermal coupling induced by the small energy bandgap between the electronic states 4F5/2 and 4F3/2. Using the fluorescence intensity ratio approach, we obtained the relative sensitivity of ∼1.7% K−1 at 300 K, which is among the highest values reported for this class of optical thermometer. We also performed the experiment using pulsed (5 ns) near-infrared excitation (750 nm) in a solution containing the Nd3+:SrF2 powder dispersed in water aiming to use this system for temperature sensing in the first near-infrared biological transparency window. The same sensor sensitivity, within experimental error, was obtained for different excitation wavelengths (532 and 750 nm) and surrounding media (air and water).
Acoustic Wood anomaly in transmitted diffraction field
Authors: Liu Jingfei , Declercq Nico F.
Published: March 2017

In acoustics, the term Wood anomaly, in analogy to the Wood anomaly in optics, has so far referred to the anomalies observed in the specular reflection spectra of acoustic waves perpendicularly incident on periodic surfaces. Inspired by the pioneering work of Jungman et al. on the study of the transmission field of a solid-fluid periodic interface, this work attempts to provide a complete experimental investigation of the transmission fields of a broadband sound pulse transmitted through a periodic liquid-solid interface as well as a periodic solid-liquid interface. At different frequencies, two types of anomalies are observed: a spectral tip and a spectral dip, which correspond, respectively, to the brighter band and the darker band in optical Wood anomalies. The search for their physical origin suggests that the type and location of the observed spectral anomalies are strongly related to the generation and the diffraction of pseudosurface waves on the interface having superimposed periodic corrugations and time-domain windowing in spectral analysis. To compare with the surface waves on a plane surface, the properties of the pseudosurface waves are also investigated through examining their phase and by comparing their amplitudes.
Observation of ferroelectric phase and large spontaneous electric polarization in organic salt of diisopropylammonium iodide
Authors: Saripalli Ravi K. , Swain Diptikanta , Prasad Siva , Nhalil Hariharan , Bhat Handady L. , Guru Row Tayur N. , Elizabeth Suja
Published: March 2017

In this manuscript, we explore diisopropylammonium iodide (DPI) for its ferroelectric properties and phase transitions. DPI showed two phase transitions which were identified by differential scanning calorimetry and dielectric and nonlinear optical measurements. From detailed structural studies it was found that the first transition at 369 K is from orthorhombic P212121 to monoclinic P21. The polar P21 phase is ferroelectric as evidenced by the pyroelectric data and has a very high value of spontaneous polarization (Ps = 33 μC cm−2), which is probably the highest among other reported bulk organic ferroelectrics. The second transition at 415 K is identified as polar monoclinic P21 space group to non-polar monoclinic P21/m. Thus, DPI has a high Curie temperature of 415 K. The large spontaneous polarization and high Curie temperature make DPI technologically important.
C70/C70:pentacene/pentacene organic heterojunction as the connecting layer for high performance tandem organic light-emitting diodes: Mechanism investigation of electron injection and transport
Authors: Guo Qingxun , Yang Dezhi , Chen Jiangshan , Qiao Xianfeng , Ahamad Tansir , Alshehri Saad M. , Ma Dongge
Published: March 2017

A high performance tandem organic light-emitting diode (OLED) is realized by employing a C70/C70:pentacene/pentacene organic heterojunction as the efficient charge generation layer (CGL). Not only more than two time enhancement of external quantum efficiency but also significant improvement in both power efficiency and lifetime are well achieved. The mechanism investigations find that the electron injection from the CGL to the adjacent electron transport layer (ETL) in tandem devices is injection rate-limited due to the high interface energy barrier between the CGL and the ETL. By the capacitance-frequency (C-F) and low temperature current density-voltage (J-V) characteristic analysis, we confirm that the electron transport is a space-charge-limited current process with exponential trap distribution. These traps are localized states below the lowest unoccupied molecular orbital edge inside the gap and would be filled with the upward shift of the Fermi level during the n-doping process. Furthermore, both the trap density (Ht) and the activation energy (Ea) could be carefully worked out through low temperature J-V measurements, which is very important for developing high performance tandem OLEDs.
Fabrication and efficiency measurement of a Mo/C/Si/C three material system multilayer Laue lens
Authors: Kubec A. , Maser J. , Formánek P. , Franke V. , Braun S. , Gawlitza P. , Leson A. , Macrander A.
Published: March 2017

In this letter, we report on the manufacturing of a multilayer Laue lens (MLL) consisting of a multilayer stack with three materials: molybdenum and silicon as the absorber and spacer layer, respectively, and carbon as transition layers. The design has four layers per period: Mo/C/Si/C. It yields 6000 zones and provides an aperture of 50 μm. This allows the MLL structure to accept a large portion of the coherent part of the beam and to achieve a small spot size. The MLL deposition was made by magnetron sputtering at the Fraunhofer IWS, and the sectioning was done by laser cutting and subsequent focused ion beam milling to a thickness that provides a good efficiency for a photon energy of 12 keV. The diffraction efficiency as a function of the tilting angle has been measured at beamline 1-BM of the Advanced Photon Source. An efficiency of almost 40% has been achieved. This shows that the material system performs well compared to MLLs made of two-materials and that it is in excellent agreement with the numerically calculated efficiency for a comparable molybdenum/silicon bilayer system lens. We conclude that the three material system offers high efficiencies and is advantageous for stress reduction in MLLs.
Upscaling high-quality CVD graphene devices to 100 micron-scale and beyond
Authors: Lyon Timothy J. , Sichau Jonas , Dorn August , Zurutuza Amaia , Pesquera Amaia , Centeno Alba , Blick Robert H.
Published: March 2017

We describe a method for transferring ultra large-scale chemical vapor deposition-grown graphene sheets. These samples can be fabricated as large as several cm2 and are characterized by magneto-transport measurements on SiO2 substrates. The process we have developed is highly effective and limits damage to the graphene all the way through metal liftoff, as shown in carrier mobility measurements and the observation of the quantum Hall effect. The charge-neutral point is shown to move drastically to near-zero gate voltage after a 2-step post-fabrication annealing process, which also allows for greatly diminished hysteresis.
Second-harmonic generation in single-mode integrated waveguides based on mode-shape modulation
Authors: Rao Ashutosh , Chiles Jeff , Khan Saeed , Toroghi Seyfollah , Malinowski Marcin , Camacho-González Guillermo Fernando , Fathpour Sasan
Published: March 2017

Second-harmonic generation is demonstrated using grating-assisted quasi-phase matching, based on waveguide-width modulation or mode-shape modulation. Applicable to any thin-film integrated second-order nonlinear waveguide, the technique is demonstrated in compact lithium niobate ridge waveguides. Fabricated devices are characterized with pulsed-pumping in the near-infrared, showing second-harmonic generation at a signal wavelength of 784 nm and propagation loss of 1 dB/cm.
Time-dependent electromechanical response of 0.93(Na1/2Bi1/2)TiO3-0.07BaTiO3 lead-free piezoceramic under constant electric field
Authors: Chen D. , Ayrikyan A. , Webber K. G. , Kamlah M.
Published: March 2017

In this study, the time-dependent electromechanical response of lead-free piezoceramic 0.93(Na1/2Bi1/2)TiO3–0.07BaTiO3 to the applied electrical field was investigated. Large creep behavior was observed in both the polarization and the strain response, which can be attributed to the transition from a nonergodic relaxor to a state with a long-range ferroelectric order. This transition under a constant electric loading is a gradual process with a cascade behavior, observed under electric fields ranging from 1.2 to 1.6 kV/mm. The critical electric field to trigger this cascade effect was found to be approximately 1.15 kV/mm. This phenomenon indicates that the electric field-induced state transition is similar to a “self-catalyzed” behavior that depends on both the magnitude of electric loading and the holding time. Following the creep experiment, the electromechanical behavior was characterized to determine the completeness of the relaxor-ferroelectric transition.
Nonlinear UV absorption properties of bulk 4H-SiC
Authors: Meyers Vincent , Mauch Daniel , Dickens James , Neuber Andreas
Published: March 2017

The intensity-dependent light absorption in bulk high-purity semi-insulating 4H-SiC at above band gap photon energies has been studied. In particular, 3.49 eV (355 nm) UV absorption of 160 μm-thick samples of varying recombination lifetimes in the intensity range of 1 mJ/cm2–30 mJ/cm2 is addressed. The effective absorption coefficient was found to vary up to 30% within this range. Assuming deep level trapping, interband absorption, and free carrier absorption as dominant processes, a four energy level model reproduces the experimentally observed absorption behavior. While nonlinearities in the optical absorption behavior of SiC have been studied previously as function of wavelength α(λ), temperature α(T) and, to a very limited extent, at below bandgap optical intensities, the presented elucidates the UV intensity-dependent nonlinear absorption behavior, α(I), of SiC at above bandgap photon energies.
A multimodal instrument for real-time in situ study of ultrasound and cavitation mediated drug delivery
Authors: Bian Shuning , Seth Anjali , Daly Dan , Carlisle Robert , Stride Eleanor
Published: March 2017

The development of a multimodal instrument capable of real-time in situ measurements of cavitation activity and effect in tissue mimicking phantoms during ultrasound and cavitation mediated drug delivery experiments is described here. The instrument features an acoustic arm that can expose phantoms to high-intensity focused-ultrasound while measuring cavitation activity and an optical arm that monitors cavitation effect using confocal microscopy. This combination of modalities allows real-time in situ characterisation of drug delivery in tissue and tissue mimicking phantoms during ultrasound and cavitation mediated drug delivery experiments. A representative result, obtained with a tissue mimicking phantom and acoustically activated droplets, is presented here as a demonstration of the instrument’s capabilities and potential applications.
The connection characteristics of flux pinned docking interface
Authors: Zhang Mingliang , Han Yanjun , Guo Xing , Zhao Cunbao , Deng Feiyue
Published: March 2017

This paper presents the mechanism and potential advantages of flux pinned docking interface mainly composed of a high temperature superconductor and an electromagnet. In order to readily assess the connection characteristics of flux pinned docking interface, the force between a high temperature superconductor and an electromagnet needs to be investigated. Based on the magnetic dipole method and the Ampere law method, the force between two current coils can be compared, which shows that the Ampere law method has the higher calculated accuracy. Based on the improved frozen image model and the Ampere law method, the force between high temperature superconductor bulk and permanent magnet can be calculated, which is validated experimentally. Moreover, the force between high temperature superconductor and electromagnet applied to flux pinned docking interface is able to be predicted and analyzed. The connection stiffness between high temperature superconductor and permanent magnet can be calculated based on the improved frozen image model and Hooke's law. The relationship between the connection stiffness and field cooling height is analyzed. Furthermore, the connection stiffness of the flux pinned docking interface is predicted and optimized, and its effective working range is defined and analyzed in case of some different parameters.
Global 3D two-fluid simulations of the tokamak edge region: Turbulence, transport, profile evolution, and spontaneous E × B rotation
Authors: Zhu Ben , Francisquez Manaure , Rogers Barrett N.
Published: March 2017

We present global two-fluid simulations of L-mode edge tokamak plasma turbulence and profile evolution including both closed field lines and the scrape-off-layer. We consider a shifted-circle magnetic configuration with realistic Alcator C-Mod inner wall limited discharge parameters. The dominant driver of turbulence in the simulations is the resistive ballooning mode. We observe spontaneous E × B rotation in the electron diamagnetic drift direction in the closed flux region in all cases. We explain this based on the steady state ion continuity relation ∇·nv→i≈0. We find that the E × B rotation in the closed flux region mostly cancels the ion diamagnetic drift as H-mode-like regimes are approached and exceeds it by a factor of 2 or more at lower temperatures due to parallel ion flows.
Enhanced laser radiation pressure acceleration of protons with a gold cone-capillary
Authors: Lv Chong , Xie Bai-Song , Wan Feng , Hou Ya-Juan , Jia Mo-Ran , Sang Hai-Bo , Hong Xue-Ren , Liu Shi-Bing
Published: March 2017

A scheme with a gold cone-capillary is proposed to improve the protons acceleration, and involved problems are investigated by using the two-dimensional particle-in-cell simulations. It is demonstrated that the cone-capillary can efficiently guide and collimate the protons to a longer distance and result in a better beam quality with a dense density ≥10nc, monoenergetic peak energy Ek∼1.51 GeV, spatial emittance ∼0.0088 mm mrad with divergence angle θ∼1.0° and diameter ∼0.5μm. The enhancement is mainly attributed to the focusing effect by the transverse electric field generated by the cone as well as the capillary, which can prevent greatly the protons from expanding in the transverse direction. Comparable to without the capillary, the protons energy spectra have a stable monoenergetic peak and divergence angle nearby 1.0° in longer time. Besides, the efficiency of acceleration depending on the capillary length is explored, and the optimal capillary length is also achieved. Such a target may be beneficial to many applications such as ion fast ignition in inertial fusion, proton therapy and so on.
A new principle technic for the transformation from frequency domain to time domain
Authors: Gao Ben-Qing
Published: March 2017

A principle technic for the transformation from frequency domain to time domain is presented. Firstly, a special type of frequency domain transcendental equation is obtained for an expected frequency domain parameter which is a rational or irrational fraction expression. Secondly, the inverse Laplace transformation is performed. When the two time-domain factors corresponding to the two frequency domain factors at two sides of frequency domain transcendental equation are known quantities, a time domain transcendental equation is reached. At last, the expected time domain parameter corresponding to the expected frequency domain parameter can be solved by the inverse convolution process. Proceeding from rational or irrational fraction expression, all solving process is provided. In the meantime, the property of time domain sequence is analyzed and the strategy for choosing the parameter values is described. Numerical examples are presented to verify the proposed theory and technic. Except for rational or irrational fraction expressions, examples of complex relative permittivity of water and plasma are used as verification method. The principle method proposed in the paper can easily solve problems which are difficult to be solved by Laplace transformation.
New approaches to VLP-based vaccines
Authors: Penumarthi Alekhya , Smooker Peter M
Published: March 2017

Vaccination is a long and established field of research, and outputs from the research have saved countless millions of lives. The early vaccines were developed with scant regard for the immunological mechanisms at play, largely because they were unknown. We are now in a position to use our knowledge of immunology to rationally design vaccines. This article focusses on the use of virus-like particles (VLPs) as vaccines.
“Scandinavia's best-kept secret.”†Tourism promotion, nation-branding, and identity construction in Estonia (with a free guided tour of Tallinn Airport)
Authors: Pawłusz Emilia , Polese Abel
Published: March 2017

This article surveys the official narrative on representation of Estonian identity and Estonianness through the tourism strategy implemented by Estonia from 2007 to 2015. Gathering material from brochures and documents targeting foreigners produced by the Estonian Institute and “Enterprise Estonia” (EAS) and analyzing the logic behind the interior design of Tallinn Airport, we engage with current debates on identity construction in post-Soviet spaces. In particular, we suggest that along with an established body of literature looking at the role of state actors in the construction of identity, studies should consider the role of nontraditional or non-state actors in identifying and promoting identity markers.
The politics of recognition, and the manufacturing of citizenship and identity in Senegal’s decentralised charcoal market
Authors: Faye Papa
Published: March 2017

This article shows how state politics of (re)allocation of rights and resources to social groups within a society (recognition) are constructive of distinct abilities to shape the fate of the political economy of natural resources (citizenship) and of specific images of self (identities). It departs from the politics of recognition applied by the Forest Service to private merchants and forest villagers in Eastern Senegal. Herein, I theorise citizenship and identity as effects of the politics of recognition and redistribution, emphasising that identities are culturally bounded categories, but are also products (through reclassification) of public institutions’ discourses, legal ordinances and practices.
Final report on CCQM-K125: elements in infant formula
Authors: Merrick J , Saxby D , Dutra E S , Sena R C , Araújo T O , Almeida M D , Yang L , Pihillagawa I G , Mester Z , Sandoval S , Wei C , Castillo M E D , Oster C , Fisicaro P , Rienitz O , Pape C , Schulz U , Jährling R , Görlitz V , Lampi E , Kakoulides E , Sin D W M , Yip Y C , Tsoi Y T , Zhu Y , Okumu T O , Yim Y H , Heo S W , Han M , Lim Y , Osuna M A , Regalado L , Uribe C , Buzoianu M M , Duta S , Konopelko L , Krylov A , Shin R , Linsky M , Botha A , Magnusson B , Haraldsson C , Thiengmanee U , Klich H , Can S Z , Coskun F G , Tunc M , Entwisle J , O'Reilly J , Hill S , Goenaga-Infante H , Winchester M , Rabb S A , Pérez R
Published: March 2017

CCQM-K125 was organized by the Inorganic Analysis Working Group (IAWG) of CCQM to assess and document the capabilities of the national metrology institutes (NMIs) or the designated institutes (DIs) to measure the mass fractions of trace elements (K, Cu and I) in infant formula. Government Laboratory, Hong Kong SAR (GLHK) acted as the coordinating laboratory.

In CCQM-K125, 25 institutes submitted the results for potassium, 24 institutes submitted the results for copper and 8 institutes submitted the results for iodine.

For examination of potassium and copper, most of the participants used microwave-assisted acid digestion methods for sample dissolution. A variety of instrumental techniques including inductively coupled plasma mass spectrometry (ICP-MS), isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS), inductively coupled plasma optical emission spectrometry (ICP-OES), atomic absorption spectrometry (AAS), flame atomic emission spectrometry (FAES) and microwave plasma atomic emission spectroscopy (MP-AES) were employed by the participants for determination. For analysis of iodine, most of the participants used alkaline extraction methods for sample preparation. ICP-MS and ID-ICP-MS were used by the participants for the determination.

Generally, the participants' results of CCQM-K125 were found consistent for all measurands according to their equivalence statements. Except with some extreme values, most of the participants obtained the values of di
/U(di
) within ± 1 for the measurands.

Main text

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Anticipated Changes in Spine Practice with Advancing Center for Medicare and Medicaid Services-Required Changes
Authors: Swartz Karin R. , Cheng Joseph S.
Published: March 2017

In providing spinal care to neurosurgical patients, cost and quality metrics are areas of interest to many. The federal government has legislated changes mandated for Centers for Medicare and Medicaid Services-enrolled patient care. The ever-changing administrative and patient-care challenges and opportunities are explored in this article, highlighting the Medicare Access and CHIP (Children's Health Insurance Program) Reauthorization Act of 2015 (MACRA), in the context of the Affordable Care Act. Trends in contemporary spinal care, addressing bundling, patient satisfaction, and ambulatory surgical centers are featured.
Macrovascular Decompression of the Brainstem and Cranial Nerves: Evolution of an Anteromedial Vertebrobasilar Artery Transposition Technique
Authors: Choudhri Omar , Connolly Ian D. , Lawton Michael T.
Published: March 2017

BACKGROUND: Tortuous and dolichoectatic vertebrobasilar arteries can impinge on the brainstem and cranial nerves to cause compression syndromes. Transposition techniques are often required to decompress the brainstem with dolichoectatic pathology. We describe our evolution of an anteromedial transposition technique and its efficacy in decompressing the brainstem and relieving symptoms.

OBJECTIVE: To present the anteromedial vertebrobasilar artery transposition technique for macrovascular decompression of the brainstem and cranial nerves.

METHODS: All patients who underwent vertebrobasilar artery transposition were identified from the prospectively maintained database of the Vascular Neurosurgery service, and their medical records were reviewed retrospectively. The extent of arterial displacement was measured pre- and postoperatively on imaging.

RESULTS: Vertebrobasilar arterial transposition and macrovascular decompression was performed in 12 patients. Evolution in technique was characterized by gradual preference for the far-lateral approach, use of a sling technique with muslin wrap, and an anteromedial direction of pull on the vertebrobasilar artery with clip-assisted tethering to the clival dura. With this technique, mean lateral displacement decreased from 6.6 mm in the first half of the series to 3.8 mm in the last half of the series, and mean anterior displacement increased from 0.8 to 2.5 mm, with corresponding increases in satisfaction and relief of symptoms.

CONCLUSION: Compressive dolichoectatic pathology directed laterally into cranial nerves and posteriorly into the brainstem can be corrected with anteromedial transposition towards the clivus. Our technique accomplishes this anteromedial transposition from an inferolateral surgical approach through the vagoaccessory triangle, with sling fixation to clival dura using aneurysm clips.
Asthma prevalence and severity in low-resource communities
Authors: Cruz Álvaro A. , Stelmach Rafael , Ponte Eduardo V.
Published: March 2017

Purpose of review

The prevalence of asthma was thought to be low in most low-income countries, but several reports have indicated this is not always true. This is a narrative review of recent publications on the burden of asthma in low and middle-income countries (LMIC) and underprivileged communities from developed countries.

Recent findings

Several studies have reported a low prevalence of asthma is LMIC, but indicate it is increasing. In the last few years, however, many surveys demonstrated this may not always be true. An analysis of the International Study for Asthma and Allergy in Childhood phase III database indicated although the prevalence of asthma among children and adolescents is higher in the developed countries, symptoms of asthma are often more severe in less affluent nations. The rate of uncontrolled asthma is also higher among underprivileged communities of developed countries. Secondary analysis of data generated by the WHO's world health survey performed among adults of 70 countries indicate symptoms of asthma are less frequent in middle-income countries and more frequent in the extremes, low income and high income. This sort of U shaped distribution suggests the disease (or syndrome) comprise more than one major phenotype related to diverse underlying mechanisms. In fact, recent reports show symptoms of asthma among the poor are associated with unhygienic living conditions, which may reduce the risk of atopy but increase the risk of nonatopic wheezing. Urbanization and exposure to air pollution also seem to contribute to an increasing prevalence severity of asthma in LMIC. Access to proper diagnosis and treatment with controller medications for asthma, specially with inhaled corticosteroids is feasible and cost-effective, reduce symptoms, health resource utilization, improves quality of life, and reduce mortality in low-resource settings.

Prevalence of asthma was thought to be low in low-income countries, but several reports have indicated this is not always true. Under diagnosis, under treatment, exposure to air pollution, and unhygienic living conditions may contribute to a higher frequency and severity of symptoms of asthma among the poor. Proper diagnosis and treatment with controller medications for asthma is feasible and cost-effective in low-resource settings.
CONTRALATERAL VISION LOSS AFTER ENDONASAL DACRYOCYSTORHINOSTOMY: A CASE REPORT OF PURTSCHER-LIKE RETINOPATHY AND TREATMENT WITH INTRAVITREAL TISSUE PLASMINOGEN ACTIVATOR
Authors: Gungel Hulya , Altan Cigdem , Karini Belma , Ozdemir Fatma E. , Celebi Ozlem O.
Published: March 2017

Purpose:

To present a case of a patient with contralateral vision loss as a result of Purtscher-like retinopathy after an endonasal dacryocystorhinostomy and treatment with intravitreal tissue plasminogen activator injection.

Methods and Results:

A 51-year-old woman who underwent a left endonasal dacryocystorhinostomy was referred with a complaint of decreased vision 1 day after surgery in her right eye. At the initial examination, the visual acuity of her right eye was hand motion. The fundoscopic examination revealed a premacular hemorrhage, diffuse intraretinal hemorrhages, multiple peripapillary cotton wool patches, and Purtscher flecken. The patient received 50 μg/0.1 mL of intravitreal tissue plasminogen activator injection. One day after the injection, visual acuity improved to 3/20. On 1-month follow-up without medication, the visual acuity improved to 6/20, and normal visual evoked potential latencies and amplitudes were detected.

Conclusion:

Purtscher- like retinopathy may occur as a complication of endonasal dacryocystorhinostomy. Intravitreal tissue plasminogen activator may help relieve the embolization that occurs in Purtscher-like retinopathy.
Disseminated Lichtheimia ramosa Infection After Hematopoietic Stem Cell Transplantation in a Child With Chronic Granulomatous Disease
Authors: Winstead Michael , Ozolek John , Nowalk Andrew , Williams John , Vander Lugt Mark , Lin Philana
Published: March 2017

Mucormycosis is uncommon in patients with chronic granulomatous disease (CGD). We report a 7-year-old boy with X-linked CGD and absent oxidative burst who developed fatal Lichtheimia ramosa infection with fungal thrombosis of the kidneys, spleen and other organs after hematopoietic stem cell transplantation. Lichtheimia infection is rarely reported in patients with CGD and could be related to iatrogenic immunosuppression.
Mycobacterium Fortuitum Bloodstream Infection in a Very Low Birth Weight Preterm Neonate
Authors: Hodgson Kate , Isabel Sandra , McNamara Patrick , Petrich Astrid , Bitnun Ari
Published: March 2017

Mycobacterium fortuitum is a rapidly growing Mycobacterium species that is a rare cause of disease, primarily in immunocompromised patients. We present a very low birth weight preterm neonate who developed M. fortuitum bloodstream infection, where 16S rDNA sequencing allowed accurate identification. Cure was achieved by line removal and adjuvant combination treatment with amikacin, ciprofloxacin and clarithromycin.
Midazolam as an active placebo in 3 fentanyl-validated nociceptive pain models
Authors: Prosenz Julian , Gustorff Burkhard
Published: March 2017

The use of inactive placebos in early translational trials of potentially analgesic compounds is discouraged because of the side-effect profiles of centrally acting analgesics. Therefore, benzodiazepines are used, although their use has not been validated in this context. Whether benzodiazepines confound the results of acute pain tests is unknown. Midazolam (0.06 mg/kg) as an active placebo was investigated in 3 nociceptive models that included contact heat, electrical pain, and pressure pain thresholds in 24 healthy volunteers. Fentanyl (1 μg/kg) served as an internal validator in this randomized, placebo (saline) controlled, 3-way cross-over trial. The primary outcome parameter (contact heat pain) was analyzed using a one-way, repeated measures analysis of variance and Tukey's post test. Midazolam did not reduce pain ([numeric rating scale], 0-100) in a statistically significant manner compared with placebo for the contact heat (mean difference −1.7, 95% confidence interval −10.6 to 7.3; P = 0.89) or electrical pain (4.3, −5.1 to 13.7; P = 0.51) test, nor did it raise the pressure pain thresholds (−28 kPa, −122; 64 kPa, P = 0.73). The width of the confidence intervals suggested that there were no clinically meaningful analgesic effects compared with the placebo. In contrast, the analgesic efficacy of fentanyl was effectively demonstrated in all 3 models (P < 0.01 vs midazolam and placebo). The findings of this study show that midazolam can be used as an active placebo in analgesic drug trials. Furthermore, the proposed models were simple to implement and very effective in detecting analgesia. The test battery can be used in translational trials for new compounds and comes with an active placebo and an optional active comparator.
Associations Between Medication Class and Subsequent Augmentation of Depression Treatment in Privately Insured US Adults
Authors: Ameli Omid , Soria-Saucedo Rene , Smith Eric G. , Cabral Howard J. , Soley-Bori Marina , Kazis Lewis E.
Published: March 2017

Importance

Treatment augmentation is an important clinical decision in the pharmacotherapy for depression, yet few studies have examined the rates of treatment augmentation by medication class.

Objective

The aim of this study was to examine which initial pharmacotherapies for depression are more likely than others to result in subsequent treatment augmentation.

Methods

This study is a retrospective cohort analysis of administrative data of 214,705 privately insured US adults between the age of 18 and 64 years who were diagnosed with a new episode of depression in 2009. Propensity score–adjusted logistic regression and Cox regression were used to model the effect of the class of initial monotherapy on treatment augmentation. Risk adjustors included depression severity, comorbidities, provider type, insurance, and demographic characteristics.

Exposure

The class of initial monotherapy and the health care provider type were the main independent variables of interest.

Main Outcome

The outcome was the augmentation of monotherapy.

Results

Thirty-four percent of individuals received treatment augmentation. Compared with selective serotonin reuptake inhibitor monotherapy, second-generation antipsychotics as the initial treatment were associated with significant increase in the likelihood of augmentation compared with the other classes (hazards ratio, 2.59; 95% confidence interval [CI], 2.51–2.68). This result was corroborated after propensity score adjustment (odds ratio, 2.85; 95% CI, 2.70–3.00) when comparing second-generation antipsychotics to the other classes of pharmacotherapy. The other significant predictor of treatment augmentation was the provider type. Mental health specialists were 27% more likely to augment a treatment compared with generalists (hazards ratio, 1.27; 95% CI, 1.25–1.30).

Conclusions

The type of initial antidepressant therapy is associated with the chances of treatment augmentation. Second-generation antipsychotics progressed to augmentation more rapidly than the other classes.
Vertical Midface Lifting with Periorbital Anchoring in the Management of Lower Eyelid Retraction: A 10-Year Clinical Retrospective Study
Authors: Pascali Michele , Botti Chiara , Cervelli Valerio , Botti Giovanni
Published: March 2017

Background:

Lower eyelid retraction can be the unfortunate result of aesthetic surgery, trauma, disease, or the aging processes. The purpose of this article is to assess whether midface lifting based on purely vertical repositioning constitutes an effective procedure for its correction.

Methods:

A retrospective study was carried out on 199 patients (311 eyelids) operated on between January of 2004 and January of 2014. The various causes of eyelid retraction in this population included cosmetic blepharoplasty (56.8 percent), involutional ectropion (23.1 percent), tumor resection (9.5 percent), facial nerve paralysis (8.5 percent), and trauma and related surgery (2 percent). The study was restricted exclusively to cases of moderate and severe lower eyelid retraction addressed by means of midface lifting. The mean follow-up time was 16.8 months. All of the patients were subjected to midface lifting with strengthening of the lateral canthus. A spacer graft was also used in 37.7 percent of the cases.

Results:

One hundred ninety-five patients (97.9 percent) displayed objective improvement of the eyelid retraction and a marked degree of improvement both in aesthetic terms and as regards the functional disorders reported. Only four patients (2 percent) presented complications such as needing another operation.

Conclusion:

Midface lifting based on purely vertical repositioning makes it possible to recruit a considerable amount of “new” skin at the lower eyelid, thus ensuring a decrease in vertical distraction and correct recovery of the height of the external lamellar plane.

CLINICAL QUESTION/LEVEL OF EVIDENCE:

Therapeutic, IV.
Spring-Assisted Cranioplasty for the Correction of Nonsyndromic Scaphocephaly: A Quantitative Analysis of 100 Consecutive Cases
Authors: Rodgers Will , Glass Graeme E. , Schievano Silvia , Borghi Alessandro , Rodriguez-Florez Naiara , Tahim Arpan , Angullia Freida , Breakey William , Knoops Paul , Tenhagen Maik , O’Hara Justine , Ponniah Allan , James Gregory , Dunaway David J. , Jeelani N. U. Owase
Published: March 2017

Background:

Spring-assisted cranioplasty has been proposed as an alternative to total calvarial remodeling for sagittal craniosynostosis. Advantages include its minimally invasive nature, and reduced morbidity and hospital stay. Potential drawbacks include the need for a second procedure for removal and the lack of published long-term follow-up. The authors present a single-institution experience of 100 consecutive cases using a novel spring design.

Methods:

All patients treated at the authors’ institution between April of 2010 and September of 2014 were evaluated retrospectively. Patients with isolated nonsyndromic sagittal craniosynostosis were included. Data were collected for operative time, anesthetic time, hospital stay, transfusion requirement, and complications in addition to cephalic index preoperatively and at 1 day, 3 weeks, and 6 months postoperatively.

Results:

One hundred patients were included. Mean cephalic index was 68 preoperatively, 71 at day 1, and 72 at 3 weeks and 6 months postoperatively. Nine patients required transfusion. Two patients developed a cerebrospinal fluid leak requiring intervention. One patient required early removal of springs because of infection. One patient had a wound dehiscence over the spring and one patient sustained a venous infarct with hemiplegia. Five patients required further calvarial remodeling surgery.

Conclusions:

The authors’ modified spring design and protocol represents an effective strategy in the management of single-suture sagittal craniosynostosis with reduced total operative time and blood loss compared with alternative treatment strategies. In patients referred within the first 6 months of birth, this technique has become the authors’ procedure of choice. In a minority of cases, especially in the older age groups, further remodeling surgery is required.

CLINICAL QUESTION/LEVEL OF EVIDENCE:

Therapeutic, IV.
Differentiation of Impaired From Preserved Hemodynamics in Patients With Fontan Circulation Using Real-time Phase-velocity Cardiovascular Magnetic Resonance
Authors: Körperich Hermann , Müller Katja , Barth Peter , Gieseke Jürgen , Haas Nikolaus , Schulze-Neick Ingram , Burchert Wolfgang , Kececioglu Deniz , Laser Kai T.
Published: March 2017

Purpose:

Progressive impairment of hemodynamics in patients with Fontan circulation is common, multifactorial, and associated with decreased quality of life and increased morbidity. We sought to assess hemodynamic differences between patients with preserved (preserved Fontans) and those with impaired circulation (impaired Fontans) after pulmonary vasodilation using oxygen and under forced breathing conditions.

Materials and Methods:

Real-time phase-contrast cardiovascular magnetic resonance was performed using non–ECG triggered echo-planar imaging (temporal resolution=24 to 28 ms) in the ascending aorta (AAo) and superior vena cava (SVC)/inferior vena cava (IVC) on room air, after 100% oxygen inhalation (4 L/min; 10 min) and on forced breathing in 29 Fontan patients (17.2±7.3 y) and in 32 controls on room air (13.4±3.7 y). The simultaneously recorded patients’ respiratory cycle was divided into 4 segments (expiration, end-expiration, inspiration, and end-inspiration) to generate respiratory-dependent stroke volumes (SVs). The imaging data were matched with physiological data and analyzed with home-made software.

Results:

The mean SVi (AAo) was 46.1±11.1 mL/m2 in preserved Fontans versus 30.4±6.2 mL/m2 in impaired Fontans (P=0.002) and 51.1±6.9 mL/m2 in controls (P=0.107). The cutoff value for differentiation of Fontan groups was SVi (AAo, end-expiratory) of 32.1 mL/m2. After hyperoxygenation, the mean SVi (AAo) increased to 48.7±12.7 mL/m2 in preserved Fontans (P=0.045) but remained unchanged in impaired Fontans (31.1±5.8 mL/m2, P=0.665). Simultaneously, heart rates decreased from 75.2±15.9 to 70.8±16.4 bpm (preserved; P=0.000) but remained unchanged in impaired circulation (baseline: 84.1±9.8 bpm, P=0.612). Compared with physiological respiration, forced breathing increased the maximum respiratory-related cardiac index difference (ΔCImax) in preserved Fontans (SVC: 2.5-fold, P=0.000; and IVC: 1.8-fold, P=0.000) and to a lower extent in impaired Fontans (both veins, 1.5-fold; P(SVC)=0.011, P(IVC)=0.013). There was no impact on mean blood flow.

Conclusions:

Oxygen affected the pulmonary vascular system by vasodilation and increased SVi in preserved Fontans but had no effect on impaired Fontans. Forced breathing increased ΔCImax but did not change the mean blood flow by sole activation of the ventilatory pump. End-expiratory aortic SVi represents a valuable measure for classifying the severity of Fontan hemodynamics impairment.
Treating the lungs via the brain: Mechanisms underpinning improvements in breathlessness with pulmonary rehabilitation
Authors: Herigstad Mari , Faull Olivia , Hayen Anja , Evans Eleanor , Hardinge Maxine F. , Wiech Katja , Pattinson Kyle T. S.
Published: March 2017

Background

Breathlessness in chronic obstructive pulmonary disease (COPD) is often discordant with airway pathophysiology (“over-perception”). Pulmonary rehabilitation has profound effects upon breathlessness, without influencing lung function. Learned associations can influence brain mechanisms of sensory perception. We therefore hypothesised that improvements in breathlessness with pulmonary rehabilitation may be explained by changing neural representations of learned associations, reducing “over-perception”.

Methods

In 31 patients with COPD, we tested how pulmonary rehabilitation altered the relationship between brain activity during learned associations with a word-cue task (using functional magnetic resonance imaging), clinical, and psychological measures of breathlessness.

Results

Improvements in breathlessness and breathlessness-anxiety correlated with reductions in word-cue related activity in the insula and anterior cingulate cortex (ACC) (breathlessness), and increased activations in attention regulation and motor networks (breathlessness-anxiety). Greater baseline (pre-rehabilitation) activity in the insula, ACC and prefrontal cortex correlated with the magnitude of improvement in breathlessness and breathlessness anxiety.

Conclusions

Pulmonary rehabilitation reduces the influence of learned associations upon neural processes that generate breathlessness. Patients with stronger word-cue related activity at baseline benefitted more from pulmonary rehabilitation. These findings highlight the importance of targeting learned associations within treatments for COPD, demonstrating how neuroimaging may contribute to patient stratification and more successful personalised therapy.