bluuebunny/crossref_metadata_2025 huggingface dataset:
Ductal variation of the sublingual gland: A predisposing factor for ranula formation
Authors: Mun Sue Jean , Choi Hyo Geun , Kim Heejin , Park Joo Hyun , Jung Young Ho , Sung Myung‐Whun , Kim Kwang Hyun
Published: June 2013

Background

The purpose of this study was to evaluate ranula development according to anatomic variation of the sublingual gland (SLG).

Methods

We conducted a prospective, consecutive case series considering other clinical conditions. Twenty‐five cases treated by SLG excision were enrolled in this study. The ductal structures of the SLGs of another 11 patients undergoing similar surgeries for other conditions were compared.

Results

In 19 of a total of 25 ranulas (76.0%) and 16 of 18 oral nonplunging ranulas (88.9%), the SLG showed an anatomic variation of the main duct called Bartholin's duct structure. Meanwhile, only 3 of 7 plunging ranulas (42.9%) had Bartholin's ducts. Bartholin's duct structure of the SLG was not found in the 11 control cases.

Conclusion

Anatomic variation of the ductal system of the SLG might be a possible cause of ranulas. Surgical resection of the SLG is a better treatment choice for ranulas than other, more conservative treatments. © 2013 Wiley Periodicals, Inc. Head Neck 36: 540–544, 2014
Autoimmune thyroiditis in benign and malignant thyroid nodules: 16‐year results
Authors: Giagourta Irene , Evangelopoulou Catherine , Papaioannou Garyfallia , Kassi Georgia , Zapanti Evangelia , Prokopiou Maria , Papapostolou Konstantinos , Karga Helen
Published: June 2013

Background

It is controversial whether autoimmune thyroiditis is associated with higher frequency of papillary thyroid carcinoma (PTC).

Methods

This was a cross‐sectional, retrospective study. PTCs were compared to benign nodules regarding the prevalence of autoimmune thyroiditis over 16 years.

Results

A similar proportion of autoimmune thyroiditis was observed in both benign and/or malignant nodules. Mean nodule size in cases with autoimmune thyroiditis was smaller than those without autoimmune thyroiditis. Multivariate analysis showed a negative association between the coexistence of autoimmune thyroiditis and lymph node and/or distant metastases. Lymph nodes involvement and distant metastases were lower in the PTC with autoimmune thyroiditis compared to those without autoimmune thyroiditis. Capsular invasion was a strong predictor for distant metastases attenuated by the presence of autoimmune thyroiditis.

Conclusion

Thyroid nodules with autoimmune thyroiditis are not more likely to be malignant than those without autoimmune thyroiditis. The coexistent autoimmune thyroiditis may be beneficial as a decreased incidence of lymph nodes involvement and distant metastasis was seen in those patients. © 2013 Wiley Periodicals, Inc. Head Neck 36: 531–535, 2014
Complexity‐reduction modelling for assessing the macro‐scale patterns of historical soil moisture in the Euro‐Mediterranean region
Authors: Diodato Nazzareno , Brocca Luca , Bellocchi Gianni , Fiorillo Francesco , Guadagno Francesco Maria
Published: June 2013

Complexity‐reduction modelling can be useful for increasing the understanding of how the climate affects basin soil moisture response upon historical times not covered by detailed hydrological data. For this purpose, here is presented and assessed an empirical regression‐based model, the European Soil Moisture Empirical Downscaling (ESMED), in which different climatic variables, easily available on the web, are addressed for simplifying the inherent complexity in the long‐time studies. To accommodate this simplification, the Palmer Drought Severity Index, the precipitation, the elevation and the geographical location were used as input data in the ESMED model for predicting annual soil moisture budget. The test area was a large region including central Europe and Mediterranean countries, and the spatial resolution was initially set at 50 km. ESMED model calibration was made according to the soil moisture values retrieved from the Terrestrial Water Budget Data archive by selecting randomly 285 grid points (out of 2606). Once parameterized, ESMED model was performed at validation stage both spatially and temporally. The spatial validation was made for the grid points not selected in the calibration stage while the comparison with the soil moisture outputs of the Global Land Data Assimilation System–NOAH10 simulations upon the period 1950–2010 was carried out for the temporal validation. Moreover, ESMED results were found to be in good agreement with a root‐zone soil moisture product obtained from active and passive microwave sensors from various satellite missions. ESMED model was thus found to be reliable for both the temporal and spatial validations and, hence, it might represent a useful tool to characterize the long‐term dynamics of soil moisture–weather interaction. Copyright © 2013 John Wiley & Sons, Ltd.
New approach for solving the inverse boundary value problem of Laplace's equation on a circle: Technique renovation of the Grad‐Shafranov (GS) reconstruction
Authors: Li H. J. , Feng X. S. , Xiang J. , Zuo P. B.
Published: June 2013

In this paper, the essential technique of Grad‐Shafranov (GS) reconstruction is reformulated into an inverse boundary value problems (IBVPs) for Laplace's equation on a circle by introducing a Hilbert transform between the normal and tangent component of the boundary gradients. It is proved that the specified IBVPs have unique solution, given the known Dirichlet and Neumann conditions on certain arc. Even when the arc is reduced to only one point on the circle, it can be inferred logically that the unique solution still exists there on the remaining circle. New solution approach for the specified IBVP is suggested with the help of the introduced Hilbert transform. An iterated Tikhonov regularization scheme is applied to deal with the ill‐posed linear operators appearing in the discretization of the new approach. Numerical experiments highlight the efficiency and robustness of the proposed method. According to linearity of the elliptic operator in GS equation, its solution can be divided into two parts. One is solved from a semilinear elliptic equation with an homogeneous Dirichlet boundary condition. The other is solved from the IBVP of Laplace's equation. It is concluded that there exists a unique solution for the so‐called elliptic Cauchy problem for the essential technique of GS reconstruction.
Pore space relevant for gas permeability in Opalinus clay: Statistical analysis of homogeneity, percolation, and representative volume element
Authors: Keller Lukas M. , Holzer Lorenz , Schuetz Philipp , Gasser Philippe
Published: June 2013

Local porosity theory in combination with percolation theory was applied to shale microstructures that were reconstructed on the basis of focused ion beam nanotomography and scanning transmission electron microscopy. This allowed characterizing pore microstructures in Opalinus clay with length scales on the order of tens of microns. In a sample from the sandy facies (with low clay content), the fraction of “larger” pores ϕ(radii~ > 15 nm) = 0.076 is substantially higher than that in the shaley facies (with a higher clay content), where ϕ(radii~ > 15 nm) = 0.015. The resolved porosity possesses a certain degree of homogeneity, and the representative volume element (RVE) of porosity can be determined in terms of a given relative error on porosity. For example, if we accept a relative error of 10%, the RVE is on the scale of a few hundreds of microns. Both pore microstructures from sandy and shaley facies show anisotropic characteristics with respect to connectivity and percolation threshold. Using finite scaling, we found percolation thresholds with critical porosities ϕc,b = 0.04–0.12 parallel to bedding and ϕc,perp = 0.11–0.19 perpendicular to bedding. The resolved porosity of the sandy facies (low clay content) is close to the percolation threshold, whereas the porosity of the shaley facies (high clay content) is below the percolation threshold. The porosity in carbonate layers is around ϕ = 0.027, and the pore size is substantially larger when compared to the pores in the clay matrix. In the analyzed sample, pores in carbonate layers are poorly connected.
Fast inversion of magnetic field maps of unidirectional planar geological magnetization
Authors: Lima Eduardo A. , Weiss Benjamin P. , Baratchart Laurent , Hardin Douglas P. , Saff Edward B.
Published: June 2013

Scanning magnetic microscopes are being increasingly utilized in paleomagnetic studies of geological samples. These instruments typically map a single component of the sample's magnetic field at close proximity with submillimeter horizontal spatial resolution. However, in most applications, an image of the magnetization distribution within the sample is desired rather than its external magnetic field. This requires carefully solving an ill‐posed inverse problem to obtain solutions that are nearly free of artifacts and consistent with both natural and laboratory magnetization processes. We present a new, fast inversion technique based on classic methods developed for the Fourier domain that retrieves planar unidirectional magnetization distributions from magnetic field maps. Whereas our approach considers the subtle peculiarities of scanning magnetic microscopy which otherwise can complicate this technique, much of the formalism and algorithms described in this work can also be directly applied to province‐scale magnetic field data from aeromagnetic surveys and may be used as an initial step in the modeling of magnetic sources with complex three‐dimensional geometries. We discuss sources of inaccuracy observed in practical implementations of the technique and present strategies to improve the quality of inversions. Numerous examples of inversion of both synthetic and experimental data demonstrate the performance of the technique under different conditions. In particular, we retrieve magnetization distributions of a Hawaiian basalt and compare it to inversions calculated in a previous work. We conclude by showing a reconstructed magnetization for the eucrite meteorite ALHA81001 that displays in high resolution the spatial distribution of high‐coercivity grains within the sample.
Spatially variable fault friction derived from dynamic modeling of aseismic afterslip due to the 2004 Parkfield earthquake
Authors: Chang Shu‐Hao , Avouac Jean‐Philippe , Barbot Sylvain , Lee Jian‐Cheng
Published: June 2013

We investigate fault friction from dynamic modeling of fault slip prior to and following the Mw 6.0 earthquake which ruptured the Parkfield segment of the San Andreas Fault in 2004. The dynamic modeling assumes a purely rate‐strengthening friction law, with a logarithmic dependency on sliding rate: . The initial state of stress is explicitly taken into account, and afterslip is triggered by the stress change induced by the earthquake source model given a priori. We consider different initial stress states and two coseismic models, and invert for the other model parameters using a nonlinear inversion scheme. The model parameters include the reference friction μ*, the friction rate dependency characterized by the quantity a‐b, assumed to be either uniform or depth dependent. The model parameters are determined from fitting the transient postseismic geodetic signal measured at continuous GPS stations. Our study provides a view of frictional properties at the kilometers scale over the 0–15 km depth illuminated by the coseismic stress change induced by the Parkfield earthquake. The reference friction is estimated to be between 0.1 and 0.5. With independent a priori constraints on the amplitude of differential stress, the range of possible values narrows down to 0.1–0.17. The friction rate coefficient a‐b is estimated to be ∼ 10− 3 − 10− 2 with a hint that it increases upward from about 1–3 × 10–3 at 3–7 km depth to about 4–7 × 10–3 at 0–1 km depth. It is remarkable that our results are consistent with frictional properties measured on rock samples recovered from the fault zone thanks to the San Andreas Fault Observatory at Depth experiment.
The common occurrence of highly supercooled drizzle and rain near the coastal regions of the western United States
Authors: Rosenfeld Daniel , Chemke Rei , DeMott Paul , Sullivan Ryan C. , Rasmussen Roy , McDonough Frank , Comstock Jennifer , Schmid Beat , Tomlinson Jason , Jonsson Haflidi , Suski Kaitlyn , Cazorla Alberto , Prather Kimberly
Published: June 2013

Highly supercooled rain and drizzle from cloud tops at −12 to −21°C down to the 0° isotherm was documented by aircraft observations in clouds over a wide range of meteorological situations under relatively pristine marine aerosol conditions. The Gulfstream‐1 aircraft during the CalWater campaign in February and early March 2011 measured clouds over the coastal waters of northern California, orographically triggered convective clouds over the foothills of the Sierra Nevada, and orographic layer clouds over Yosemite National Park. Supercooled drizzle in layer clouds near Juneau, Alaska, was measured by the Wyoming King Air as part of a FAA project to study aircraft icing in this region. Low concentrations of cloud condensation nuclei (CCN) were commonly observed in all of these clouds, allowing for the formation of clouds with small concentrations of mostly large drops that coalesced into supercooled drizzle and raindrops. Another common observation was the absence of ice nuclei (IN) and/or ice crystals in measurable concentrations, associated with persistent supercooled drizzle and rain. Average ice crystal concentrations were 0.007 l−1 at the top of convective clouds at −12°C and 0.03 l−1 in the case of layer clouds at −21°C. In combination, these two conditions of low concentrations of CCN and very few IN provide ideal conditions for the formation of highly supercooled drizzle and rain. These results help explain the anomalously high incidences of aircraft icing at cold temperatures in U.S. west coast clouds and highlight the need to include aerosol effects when simulating aircraft icing with cloud models.
Repetitive differential finger motion increases shear strain between the flexor tendon and subsynovial connective tissue
Authors: Tat Jimmy , Kociolek Aaron M. , Keir Peter J.
Published: June 2013

Non‐inflammatory fibrosis and thickening of the subsynovial connective tissue (SSCT) are characteristic in carpal tunnel syndrome (CTS) patients. These pathological changes have been linked to repetitive hand tasks that create shear forces between the flexor tendons and SSCT. We measured the relative motion of the flexor digitorum superficialis tendon and SSCT during two repetitive finger tasks using color Doppler ultrasound. Twelve participants performed flexion−extension cycles for 30 min with the long finger alone (differential movement) and with all four fingers together (concurrent movement). Shear strain index (SSI, a relative measure of excursion in flexion and extension) and maximum velocity ratio (MVR, the ratio of SSCT versus tendon during flexion and extension) were used to represent shear. A linear effect of exertion time was significant and corresponded with larger tendon shear in differential motion. The flexion SSI increased 20.4% from the first to the 30th minute, while MVR decreased 8.9% in flexion and 8.7% in extension. No significant changes were found during concurrent motion. These results suggest that exposure to repetitive differential finger tasks may increase the risk of shear injury in the carpal tunnel. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1533–1539, 2013.
Observation of persistent α‐helical content and discrete types of backbone disorder during a molten globule to ordered peptide transition via deep‐UV resonance Raman spectroscopy
Authors: Brown Mia C. , Mutter Andrew C. , Koder Ronald L. , JiJi Renee D. , Cooley Jason W.
Published: June 2013

The molten globule (MG) state can aid in the folding of a protein to a functional structure and is loosely defined as an increase in structural disorder with conservation of the ensemble secondary structure content. Simultaneous observation of persistent secondary structure content with increased disorder has remained experimentally problematic. As a consequence, modeling how the MG state remains stable and how it facilitates proper folding remains difficult due to a lack of amenable spectroscopic techniques to characterize this class of partially unfolded proteins. Previously, deep‐UV resonance Raman (dUVRR) spectroscopy has proven useful in the resolution of global and local structural fluctuations in the secondary structure of proteins. In this work, dUVRR was employed to study the MG to ordered transition of a model four‐helix bundle protein, HP7. Both the average ensemble secondary structure and types of local disorder were monitored, without perturbation of the solvent, pH, or temperature. The MG to ordered transition is induced by stepwise coordination of two heme molecules. Persistent dUVRR spectral features in the amide III region at 1295–1301 and 1335–1338 cm−1 confirm previous observations that HP7 remains predominantly helical in the MG versus the fully ordered state. Additionally, these spectra represent the first demonstration of conserved helical content in a MG protein. With successive heme binding, significant losses are observed in the spectral intensity of the amide III3 and S regions (1230–1260 and 1390 cm−1, respectively), which are known to be sensitive to local disorder. These observations indicate that there is a decrease in the structural populations able to explore various extended conformations with successive heme binding events. DUVRR spectra indicate that the first heme coordination between two helical segments diminishes exploration of more elongated backbone structural conformations in the inter‐helical regions. A second heme coordination by the remaining two helices further restricts protein motion. Copyright © 2013 John Wiley & Sons, Ltd.
Ion beam engineered nano silver silicon substrates for surface enhanced Raman spectroscopy
Authors: Wijesundera Dharshana N. , Rajapaksa Indrajith , Wang Xeumei , Liu Jia‐Rui , Rusakova Irene , Chu Wei‐Kan
Published: June 2013

We demonstrate a method for engineering substrates for surface enhanced Raman spectroscopy (SERS) by Ag− ion implantation in Si. The implantation dose and beam current density are chosen such that the Ag concentration in Si exceeds the solid solubility limit, causes aggregation of Ag and nucleates Ag nano particles. The embedded nano particles are then partially exposed by a wet etch process. Our measurements show that the so fabricated nano‐composite substrates are very effective as stable and reproducible SERS substrates. Copyright © 2013 John Wiley & Sons, Ltd.
The calculation of the distance to a nearby defective matrix
Authors: Akinola R. O. , Freitag M. A. , Spence A.
Published: June 2013

The distance of a matrix to a nearby defective matrix is an important classical problem in numerical linear algebra, as it determines how sensitive or ill‐conditioned an eigenvalue decomposition of a matrix is. The concept has been discussed throughout the history of numerical linear algebra, and the problem of computing the nearest defective matrix first appeared in Wilkinsons famous book on the algebraic eigenvalue problem. In this paper, a new fast algorithm for the computation of the distance of a matrix to a nearby defective matrix is presented. The problem is formulated following Alam and Bora introduced in (2005) and reduces to finding when a parameter‐dependent matrix is singular subject to a constraint. The solution is achieved by an extension of the implicit determinant method introduced by Spence and Poulton in (2005). Numerical results for several examples illustrate the performance of the algorithm. Copyright © 2013 John Wiley & Sons, Ltd.
Reliability of long-term monitoring data
Authors: Anderegg Peter , Brönnimann Rolf , Meier Urs
Published: June 2013

Increasing loads, aging, new construction materials like CFRP (carbon fiber reinforced polymers) and also cost pressure are influences for fitness of traffic infrastructures, especially bridges. Prolonged health monitoring can be a means to compete with these challenges. The lifetime of infrastructure can reach 100 years, while that of sensors is typically much shorter. Therefore, sensors need to be long-term qualified and might have to be replaced by new sensors or even another sensor system during the life cycle of a structure. A reliable system for data acquisition and data analysis will be essential: Do the measurement data really relate to the monitored infrastructure and are not an effect of the degradation of the sensing system? We discuss measurement uncertainty and reliability of data obtained by different sensor types, including resistance strain gages, fiber optical sensors and other sensors systems which are in service up to 17 years.
Leveraging Metabolomics to Assess the Next Generation of Temozolomide-Based Therapeutic Approaches for Glioblastomas
Authors: St-Coeur Patrick-Denis , Touaibia Mohamed , Cuperlovic-Culf Miroslava , Morin Pier Jr
Published: June 2013

Glioblastoma multiforme (GBM) is the most common adult primary tumor of the central nervous system. The current standard of care for glioblastoma patients involves a combination of surgery, radiotherapy and chemotherapy with the alkylating agent temozolomide. Several mechanisms underlying the inherent and acquired temozolomide resistance have been identified and contribute to treatment failure. Early identification of temozolomide-resistant GBM patients and improvement of the therapeutic strategies available to treat this malignancy are of uttermost importance. This review initially looks at the molecular pathways underlying GBM formation and development with a particular emphasis placed on recent therapeutic advances made in the field. Our focus will next be directed toward the molecular mechanisms modulating temozolomide resistance in GBM patients and the strategies envisioned to circumvent this resistance. Finally, we highlight the diagnostic and prognostic value of metabolomics in cancers and assess its potential usefulness in improving the current standard of care for GBM patients.
Structure and X-ray reference diffraction patterns of (Ba6−xSrx)R2Co4O15 (x = 1, 2) (R = lanthanides)
Authors: Wong-Ng W. , Liu G. , Yan Y.G. , Kaduk J.A.
Published: May 2013

The structure and X-ray patterns of two series of barium lanthanide cobaltates, namely, Ba4Sr2R2Co4O15 (R = La, Nd, Sm, Eu, Gd, and Dy), and Ba5SrR2Co4O15 (R = La, Nd, Sm, Eu, and Gd) have been determined. These compounds crystallize in the space group P63mc; the unit-cell parameters of Ba4Sr2R2Co4O15 (R from La to Dy) decrease from a = 11.6128(2) Å to 11. 5266(9) Å, c = 6.869 03(11) to 6. 7630(5) Å, and V = 802.23(3) Å3 to 778.17(15) Å3, respectively. In the Ba5SrR2Co4O15 series (R = La to Gd), the unit-cell parameters decrease from a = 11.735 44(14) Å to 11.619 79(12) Å, c = 6.942 89 (14) Å to 6.836 52(8) Å, and V = 828.08(3) Å3 to 799.40(2) Å3. In the general structure of (Ba6−xSrx)R2Co4O15, there are four Co ions per formula unit occupying one CoO6 octahedral and three CoO4 tetrahedral units. Through corner-sharing of these polyhedra, a larger Co4O15 unit is formed. Sr2+ ions adopt both octahedral and 8-fold coordination environment. R3+ ions adopt 8-fold coordination (mixed site with Sr), while the larger Ba2+ ions assume both 10- and 11-fold coordination environments. The samples were found to be insulators. X-ray diffraction patterns of these samples have been determined and submitted to the Powder Diffraction File (PDF).
Viewing Peace Through Gender Lenses
Authors: Sjoberg Laura
Published: May 2013

The war in Iraq is over. U.S. troops have withdrawn. Saddam Hussein has been overthrown and replaced with a government perceived to be more democratic and more just to the Iraqi people. In late 2011, concurrent with the U.S. withdrawal, strategists suggested that there was “peace at last” in Iraq, a cause for celebration.
Pathologic Fractures in Bisphosphonate-Related Osteonecrosis of the Jaw—Review of the Literature and Review of Our Own Cases
Authors: Otto Sven , Pautke Christoph , Hafner Sigurd , Hesse Ronny , Reichardt Lea Franziska , Mast Gerson , Ehrenfeld Michael , Cornelius Carl-Peter
Published: June 2013

Background

Bisphosphonates are powerful drugs used for the management of osteoporosis and metastatic bone disease to avoid skeletal-related complications. Side effects are rare but potentially serious such as the bisphosphonate-related osteonecrosis of the jaws (BRONJ). BRONJ impairs the quality of life and can even lead to pathologic fractures of the mandible. Management of BRONJ is difficult per se. If complicated with pathologic mandibular fractures in advanced stages, the treatment options are controversially discussed. This review delineates the epidemiology and pathogenesis of BRONJ to put the various modalities for the treatment of pathologic mandible fractures into perspective.

Methods

Various case reports and case series in the literature were reviewed. Cases were reviewed of patients suffering from pathologic fracture due to bisphosphonate-related osteonecrosis of the jaw treated in the Department of Oral and Maxillofacial Surgery (Ludwig-Maximilians-University of Munich) from 2003 to 2010. Of 140 patients suffering from BRONJ, four were identified with pathologic fracture of the mandible.

Results

Management of pathologic mandibular fractures in patients suffering from BRONJ is an unsolved issue. At present there is a paucity of information to establish reliable therapy guidelines. The published strategies range from conservative treatment to major bone resections with or without internal or external fixation and with or without autogenous reconstruction. There is no evidence for the superiority of a single therapeutic mode, however.

Conclusion

Further understanding of BRONJ is mandatory to establish a sound rationale for the treatment of associated mandibular fractures.
Pathologic Fracture of the Mandible Secondary to Traumatic Bone Cyst
Authors: Ahlers Eric , Setabutr Dhave , Garritano Frank , Adil Eelam , McGinn Johnathan
Published: June 2013

The traumatic bone cyst (TBC) is an uncommon and poorly understood lesion. First described in 1929, TBCs lack an epithelial lining, typically occur during the second decade of life, and are most frequently located in the jaw. Although the majority of TBCs are asymptomatic, rarely a TBC can cause a pathologic fracture of the mandible. We present a case of an adolescent suffering a sports-related pathologic mandible fracture secondary to a traumatic bone cyst.
Simplified Transoral Load-Bearing Osteosynthesis with Preformed Mandible Reconstruction Plates
Authors: Schiel Sebastian , Otto Sven , Pautke Christoph , Cornelius Carl-Peter , Probst Florian A.
Published: June 2013

Transcutaneous submandibular approaches are the preferred technique for the application of load-bearing mandibular osteosynthesis plates. However, an extraoral approach is associated with several shortcomings, like the risk of harming the facial nerve and scarring. This technical note presents a specialized mandibular reconstruction plate (MatrixMANDIBLE Preformed Reconstruction Plate [Synthes Maxillofacial, Paoli, PA]), simplifying the transoral application by its design with a preformed curvature along the lateral surface of the mandible. The application of wide-spanning plates reaching from the posterior margin of the ramus even into the contralateral body region is facilitated. Transoral application of preformed mandibular reconstruction plates seems to be a promising option to bypass external incisions and to reduce operating room time.
Radiative reverse shock laser experiments relevant to accretion processes in cataclysmic variables
Authors: Krauland C. M. , Drake R. P. , Kuranz C. C. , Sweeney R. , Grosskopf M. , Klein S. , Gillespie R. , Keiter P. A. , Loupias B. , Falize E.
Published: June 2013

We discuss the production of radiative reverse shocks in experiments at the Omega-60 laser facility. The ability of this high-intensity laser to impart large energy densities on micron-thin foils makes it feasible to create supersonic plasma flows. Obtaining a radiative reverse shock in the laboratory requires a sufficiently fast flow (∼100 km/s) of a material whose opacity is large enough to produce energetically significant emission from experimentally achievable shocked layers. The reverse shock forms in the flow once it is impeded. This paper presents the first radiographic data of normal incidence, reverse shockwaves. These experiments are primarily motivated by the contribution of radiative reverse shock waves to the evolving dynamics of the cataclysmic variable (CV) system in which they reside. We show similarity properties to suggest that the experimental production of radiative reserve shocks in the laboratory may be scalable to such astrophysical systems.
A scaling relation for the capillary-pressure driven drainage of thin films
Authors: Frostad J. M. , Walter J. , Leal L. G.
Published: June 2013

Hydrodynamic interactions between deformable particles such as drops or vesicles are an integral part of the rheology of emulsions and suspensions. In addition, the drainage of the thin film separating two colliding drops or vesicles is crucial for understanding the dynamics of coalescence or adhesion, which can lead to phase separation. However, despite several decades of study, this phenomenon is still not well understood and existing analytical theories do not agree quantitatively with experimental and numerical results. In this article, new scaling arguments are presented to analyze the drainage process, once the film becomes sufficiently thin. In particular, it is shown that the length over which the pressure varies in the film changes as the film drains, and follows a specific scaling relation. The mass balance in the film is then revisited in light of the new scaling for the pressure gradient. Numerical simulations are conducted to test the new scaling arguments and evaluate the revised mass balance. In the case of vesicles, they exhibit an excellent fit with the new scaling theory. The theory is also found to apply well to drops, but only when the flow inside the drops is determined predominantly by the flow in the thin film rather than by the ambient flow.
Identification of the effects of the nozzle-exit boundary-layer thickness and its corresponding Reynolds number in initially highly disturbed subsonic jets
Authors: Bogey Christophe , Marsden Olivier
Published: June 2013

The influence of the nozzle-exit boundary-layer thickness in isothermal round jets at a Mach number of 0.9 and at diameter Reynolds numbers ReD ≃ 5 × 104 is investigated using large-eddy simulations. The originality of this work is that, contrary to previous studies on the topic, the jets are initially highly disturbed, and that the effects of the boundary-layer thickness are explored jointly on the exit turbulence, the shear-layer and jet flow characteristics, and the acoustic field. The jets originate from a pipe of radius r0, and exhibit, at the exit, peak disturbance levels of 9% of the jet velocity, and mean velocity profiles similar to laminar boundary-layer profiles of thickness δ0 = 0.09r0, 0.15r0, 0.25r0, or 0.42r0, yielding 99% velocity thicknesses between 0.07r0 and 0.34r0 and momentum thicknesses δθ(0) between 0.012r0 and 0.05r0. Two sets of computations are reported to distinguish, for the first time to the best of our knowledge, between the effects of the ratio δ0/r0 and of the Reynolds number Reθ based on δθ(0). First, four jets with a fixed diameter, hence at a constant Reynolds number ReD = 5 × 104 giving Reθ = 304, 486, 782, and 1288 depending on δ0, are considered. In this case, due to the increase in Reθ, thickening the initial shear layers mainly results in a weaker mixing-layer development with lower spreading rates and turbulence intensities, and reduced sound levels at all emission angles. Second, four jets at Reynolds numbers ReD between 1.8 × 104 and 8.3 × 104, varying so as to obtain Reθ ≃ 480 in all simulations, are examined. Here, increasing δ0/r0 has a limited impact on the mixing-layer key features, but clearly leads to a shorter potential core, a more rapid velocity decay, and higher fluctuations on the jet axis, and stronger noise in the downstream direction. Similar trends can be expected for high-Reynolds-number jets in which viscosity plays a negligible role.
Turbulent premixed combustion in V-shaped flames: Characteristics of flame front
Authors: Kheirkhah S. , Gülder Ö. L.
Published: June 2013

Flame front characteristics of turbulent premixed V-shaped flames were investigated experimentally using the Mie scattering and the particle image velocimetry techniques. The experiments were performed at mean streamwise exit velocities of 4.0, 6.2, and 8.6 m/s, along with fuel-air equivalence ratios of 0.7, 0.8, and 0.9. Effects of vertical distance from the flame-holder, mean streamwise exit velocity, and fuel-air equivalence ratio on statistics of the distance between the flame front and the vertical axis, flame brush thickness, flame front curvature, and angle between tangent to the flame front and the horizontal axis were studied. The results show that increasing the vertical distance from the flame-holder and the fuel-air equivalence ratio increase the mean and root-mean-square (RMS) of the distance between the flame front and the vertical axis; however, increasing the mean streamwise exit velocity decreases these statistics. Spectral analysis of the fluctuations of the flame front position depicts that the normalized and averaged power-spectrum-densities collapse and show a power-law relation with the normalized wave number. The flame brush thickness is linearly correlated with RMS of the distance between the flame front and the vertical axis. Analysis of the curvature of the flame front data shows that the mean curvature is independent of the experimental conditions tested and equals to zero. Values of the inverse of the RMS of flame front curvature are similar to those of the integral length scale, suggesting that the large eddies in the flow make a significant contribution in wrinkling of the flame front. Spectral analyses of the flame front curvature as well as the angle between tangent to the flame front and the horizontal axis show that the power-spectrum-densities feature a peak. Value of the inverse of the wave number pertaining to the peak is larger than that of the integral length scale.
Using optimally tuned range separated hybrid functionals in ground-state calculations: Consequences and caveats
Authors: Karolewski Andreas , Kronik Leeor , Kümmel Stephan
Published: June 2013

Optimally tuned range separated hybrid functionals are a new class of implicitly defined functionals. Their important new aspect is that the range separation parameter in these functionals is determined individually for each system by iteratively tuning it until a fundamental, non-empirical condition is fulfilled. Such functionals have been demonstrated to be extremely successful in predicting electronic excitations. In this paper, we explore the use of the tuning approach for predicting ground state properties. This sheds light on one of its downsides – the violation of size consistency. By analyzing diatomic molecules, we reveal size consistency errors up to several electron volts and find that binding energies cannot be predicted reliably. Further consequences of the consistent ground-state use of the tuning approach are potential energy surfaces that are qualitatively in error and an incorrect prediction of spin states. We discuss these failures, their origins, and possibilities for overcoming them.
The effect of laser pulse shape variations on the adiabat of NIF capsule implosions
Authors: Robey H. F. , MacGowan B. J. , Landen O. L. , LaFortune K. N. , Widmayer C. , Celliers P. M. , Moody J. D. , Ross J. S. , Ralph J. , LePape S. , Berzak Hopkins L. F. , Spears B. K. , Haan S. W. , Clark D. , Lindl J. D. , Edwards M. J.
Published: June 2013

Indirectly driven capsule implosions on the National Ignition Facility (NIF) [Moses et al., Phys. Plasmas 16, 041006 (2009)] are being performed with the goal of compressing a layer of cryogenic deuterium-tritium (DT) fuel to a sufficiently high areal density (ρR) to sustain the self-propagating burn wave that is required for fusion power gain greater than unity. These implosions are driven with a temporally shaped laser pulse that is carefully tailored to keep the DT fuel on a low adiabat (ratio of fuel pressure to the Fermi degenerate pressure). In this report, the impact of variations in the laser pulse shape (both intentionally and unintentionally imposed) on the in-flight implosion adiabat is examined by comparing the measured shot-to-shot variations in ρR from a large ensemble of DT-layered ignition target implosions on NIF spanning a two-year period. A strong sensitivity to variations in the early-time, low-power foot of the laser pulse is observed. It is shown that very small deviations (∼0.1% of the total pulse energy) in the first 2 ns of the laser pulse can decrease the measured ρR by 50%.
Recovering lost excitons in organic photovoltaics using a transparent dissociation layer
Authors: Barito A. , Sykes M. E. , Bilby D. , Amonoo J. , Jin Y. , Morris S. E. , Green P. F. , Kim J. , Shtein M.
Published: June 2013

In organic photovoltaic (OPV) cells, photocurrent generation relies on exciton diffusion to the donor/acceptor heterojunction. Excitons that fail to reach the heterojunction are lost to recombination via quenching at the electrodes or relaxation in the bulk. Bulk recombination has been mitigated largely through the use of bulk heterojunctions, while quenching at the metal cathode has been previously circumvented through the introduction of exciton blocking layers that “reflect” excitons. Here, we investigate an alternative concept of a transparent exciton dissociation layer (EDL), a single layer that prevents exciton quenching at the electrode while also providing an additional interface for exciton dissociation. The additional heterojunction reduces the distance excitons must travel to dissociate, recovering the electricity-generating potential of excitons otherwise lost to heat. We model and experimentally demonstrate this concept in an archetypal subphthalocyanine/fullerene planar heterojunction OPV, generating an extra 66% of photocurrent in the donor layer (resulting in a 27% increase in short-circuit current density from 3.94 to 4.90 mA/cm2). Because the EDL relaxes the trade-off between exciton diffusion and optical absorption efficiencies in the active layers, it has broad implications for the design of OPV architectures and offers additional benefits over the previously demonstrated exciton blocking layer for photocurrent generation.
Pure rotational spectroscopy of the H2O−trans-HOCO complex
Authors: Oyama Takahiro , Nakajima Masakazu , Sumiyoshi Yoshihiro , Endo Yasuki
Published: June 2013

Pure rotational spectra of the H2O−trans-HOCO complex have been observed by Fourier transform microwave (FTMW) spectroscopy and millimeter-wave FTMW double resonance spectroscopy. The complex was produced in a supersonic jet by discharging a mixture gas of CO and H2O diluted in Ar. The observed rotational lines consist of two groups of transitions with different hyperfine patterns. This is explained by considering the internal rotation of the H2O monomer in the complex. The molecular constants including the fine and hyperfine coupling constants have been determined for the two groups of lines. The hydrogen bond distance between H2O and the trans-HOCO monomer has also been determined with other structural parameters fixed to ab initio values. The hydrogen bond distance, 1.794 Å, is much shorter than that of the water dimer, and similar to those of water−acid complexes. The Fermi coupling constant of the proton of HOCO is compared with that of the trans-HOCO monomer, leading to the conclusion that there is an induced effect on the spin density on the proton of HOCO by the complex formation.
Cryogenic cooling with cryocooler on a rotating system
Authors: Oguri S. , Choi J. , Kawai M. , Tajima O.
Published: June 2013

We developed a system that continuously maintains a cryocooler for long periods on a rotating table. A cryostat that holds the cryocooler is set on the table. A compressor is located on the ground and supplies high-purity (>99.999%) and high-pressure (1.7 MPa) helium gas and electricity to the cryocooler. The operation of the cryocooler and other instruments requires the development of interface components between the ground and rotating table. A combination of access holes at the center of the table and two rotary joints allows simultaneous circulation of electricity and helium gas. The developed system provides two innovative functions under the rotating condition, cooling from room temperature and the maintenance of a cold condition for long periods. We have confirmed these abilities as well as temperature stability under a condition of continuous rotation at 20 rpm. The developed system can be applied in various fields, e.g., in tests of Lorentz invariance, searches for axion, radio astronomy, and cosmology, and application of radar systems. In particular, there is a plan to use this system for a radio telescope observing cosmic microwave background radiation.
The role of lock-in phase setting in ac susceptibility measurement
Authors: Drobac D. , Marohnic Z. , Zivkovic I. , Prester M.
Published: June 2013

Method in which lock-in detectors process signals from standard ac susceptometers, particularly in the detection of higher harmonics, is analyzed in details. The exact formulas have been derived and checked experimentally by measurements on soft ferromagnetic sample, using several available lock-in amplifiers. The reasons why the proper phase adjustment has to be implemented in the protocol of higher harmonics measurements have been elaborated. The procedure of the lock-in phase adjustment is described, enabling separation of Fourier or Taylor components of hysteretic ac susceptibility into real and imaginary sectors.
Restricted primitive model for electrolyte solutions in slit-like pores with grafted chains: Microscopic structure, thermodynamics of adsorption, and electric properties from a density functional approach
Authors: Pizio Orest , Sokołowski Stefan
Published: June 2013

We apply a density functional theory to describe properties of a restricted primitive model of an ionic fluid in slit-like pores. The pore walls are modified by grafted chains. The chains are built of uncharged or charged segments. We study the influence of modification of the pore walls on the structure, adsorption, ion selectivity, and the electric double layer capacitance of ionic fluid under confinement. The brush built of uncharged segments acts as a collection of obstacles in the walls vicinity. Consequently, separation of charges requires higher voltages, in comparison to the models without brushes. At high grafting densities the formation of crowding-type structure is inhibited. The double layer structure becomes more complex in various aspects, if the brushes are built of charged segments. In particular, the evolution of the brush height with the bulk fluid density and with the charge on the walls depends on the length of the blocks of charged spheres as well as on the distribution of charged species along chains. We also investigated how the dependence of the double layer capacitance on the electrostatic potential (or on the charge on the walls) changes with grafting density, the chain length, distribution of charges along the chain, the bulk fluid density, and, finally, with the pore width. The shape of the electric double layer capacitance vs. voltage changes from a camel-like to bell-like shape, if the bulk fluid density changes from low to moderate and high. If the bulk density is appropriately chosen, it is possible to alter the shape of this curve from the double hump to single hump by changing the grafting density. Moreover, in narrow pores one can observe the capacitance curve with even three humps for a certain set of parameters describing brush. This behavior illustrates how strong the influence of brushes on the electric double layer properties can be, particularly for ionic fluids in narrow pores.
Phase transformations in hypereutectic MgO-Y2O3 nanocomposites at 5.5 GPa
Authors: Şavklıyıldız İ. , Akdoğan E. K. , Zhong Z. , Wang L. , Weidner D. , Vaughan M. , Croft M. C. , Tsakalakos T.
Published: June 2013

Hypereutectic 0.8MgO-0.2Y2O3 nanocomposites were studied using high pressure and high temperature in situ synchrotron energy dispersive x-ray diffractometry at 5.5 GPa and 1273 K. Polymorphic transformations in the Y2O3 phase, which resulted in a quadruple phase equilibria among cubic, hexagonal, and monoclinic phases with cubic MgO, were observed at 298 K under 5.5 GPa—a pressure much smaller than the pressures at which polymorphic transitions in macroscopic Y2O3. Time-resolved diffractometry at (1273 K, 5.5 GPa, 120 min) revealed a 0.87% expansive volumetric lattice strain in MgO, and is attributed to solid solution formation with Y2O3 which is otherwise absent at ambient conditions. The residual MgO unit cell volume expansion is 0.69% at 298 K, which is indicative that yttrium remained in solid solution. The macroscopic shrinkage due to densification at (1273 K, 5.5 GPa, 120 min) is 3.45% by volume. The partial molar volume of Y3+ in the solid solution is smaller than its molar volume in the pure state per thermodynamic considerations. The importance of repulsion among O2− ions in the immediate vicinity of a Mg2+ vacancy as well as misfit strain due to differences in ionic radii upon Y3+ substitution on Mg2+ sites is presented. A self-consistent model and explanation for the observed concomitant occurrence of cubic → monoclinic and cubic → hexagonal polymorphic transitions in Y2O3 and their stabilization at room temperature is proposed.
Role of deposition magnetic field on magnetic properties and their unusual thermal behaviors of FeCoZr films prepared by gradient composition sputtering
Authors: Phuoc Nguyen N. , Ong C. K.
Published: June 2013

We report our systematic investigation of the temperature-dependent microwave properties of FeCoZr fabricated by gradient-composition sputtering technique with regards to the variation of the Zr deposition power with and without magnetic field applied during deposition. Specifically, we show that the films fabricated by this special method may have a peculiar thermal behavior whereby the magnetic anisotropy is increased with temperature if the induced magnetic anisotropy is sufficiently large. Moreover, our study reveals that the magnetic field applied during deposition process plays a vital role for the increment of the stress-induced magnetic anisotropy, which is useful for enhancing the resonance frequency as well as its thermal stability.
Efficient infrared thermal emitters based on low-albedo polaritonic meta-surfaces
Authors: Neuner Burton , Wu Chihhui , Eyck Gregory Ten , Sinclair Michael , Brener Igal , Shvets Gennady
Published: June 2013

A low-albedo all-semiconductor meta-surface with spectrally selective absorption peaks is demonstrated. By engineering the dimensions and shapes of the semiconductor antennas comprising the meta-surface, simultaneous reduction of reflectivity and enhancement of absorption are accomplished by controlling their electric and magnetic resonances. Thermal emissivity of the silicon carbide-based meta-surface is experimentally measured and found in agreement with both absorption measurements and theoretical predictions.