bluuebunny/crossref_metadata_2025 huggingface dataset:
The spatial origin of −5/3 spectra in grid-generated turbulence
Authors: Laizet S. , Nedić J. , Vassilicos J. C.
Published: June 2015

A combined wind tunnel and computational study of grid-generated turbulence along the centreline shows that the close to −5/3 power law signature of energy spectra in the frequency domain originates relatively close to the grid not only where the velocity derivative statistics become quite suddenly isotropic but also where the turbulent fluctuating velocities are very intermittent and non-Gaussian. As the inlet flow velocity increases, these power laws are increasingly well defined and increasingly close to −5/3 over an increasing range of frequencies. However, this range continuously decreases with streamwise distance from the grid even though the local Reynolds number first increases and then decreases along the same streamwise extent. The intermittency at the point of origin of the close to −5/3 power spectra consists of alternations between intense vortex tube clusters with shallow broad-band spectra and quiescent regions where the velocity fluctuations are smooth with steep energy spectra.
Turbulence modification by inertial particles and its influence on the spectral energy budget in planar Couette flow
Authors: Richter David H.
Published: June 2015

Two-way coupled, particle-laden simulations are performed in turbulent Couette flow with the purpose of investigating the spectral extent of the particle influence on the turbulent energy cascade in wall-bounded flows. Direct numerical simulation of the carrier phase is performed in conjunction with the Lagrangian point-particle approximation for particles of three distinct inertia ranges: StK=O(1),O(10),O(100). Simulations are also performed at three increasing Reynolds numbers (Reτ≈125,325,900) to determine the longevity of these effects as the scale separation between large and small motions is increased. A spectral decomposition of the turbulent kinetic energy (TKE) budget shows that two simultaneous effects of particles are occurring: first, the mere presence of particles causes a reduction of TKE production across nearly the entire wavenumber range, where the particle Stokes number only determines the magnitude of this reduction; second, the direct energy exchange term between the carrier and dispersed phases is relatively small in magnitude compared to changes in production; however, its location in wavenumber space is highly dependent on Stokes number and is influenced heavily by preferential concentration. The combined effect of these distinct processes is important to consider when developing large eddy simulation (or any other) two-way coupled particle-laden turbulence parameterizations.
Dynamics of magnetic field penetration into soft ferromagnets
Authors: Ducharne B. , Sebald G. , Guyomar D. , Litak G.
Published: June 2015

We propose an approach to solve the coupled problem of the magnetic field penetration into soft ferromagnets and a frequency dependent magnetic hysteresis. The magnetic field diffusion is related to the macroscopic eddy currents. The hysteresis model is related to the microscopic eddy currents derived from the magnetic domain wall movements, and is responsible for the frequency dependence of hysteresis loops. In this paper, based on a lumped model and fractional derivative operators, we demonstrate that it is possible to replace the coupled diffusion/dynamic hysteresis in a simplest formulation using fractional operators. Such a formulation can be solved easily. Instead of solving a 1D problem of diffusion, we show here that a lumped model with appropriate fractional time derivative operator can be an exact formulation of the problem. In addition, we confirm that the model is using experimental available information, obtained by standard single sheet tester measuring bench (the tangential surface excitation field, and the cross section average induction).
Direct band gap measurement of Cu(In,Ga)(Se,S)2 thin films using high-resolution reflection electron energy loss spectroscopy
Authors: Heo Sung , Lee Hyung-Ik , Song Taewon , Park Jong-Bong , Ko Dong-Su , Chung JaeGwan , Kim KiHong , Kim Seong Heon , Yun Dong-Jin , Ham YongNam , Park Gyeong Su , Lee Dongho , Nam Junggyu , Kang Hee Jae , Choi Pyung-Ho , Choi Byoung-Deog
Published: June 2015

To investigate the band gap profile of Cu(In1−x,Gax)(Se1−ySy)2 of various compositions, we measured the band gap profile directly as a function of in-depth using high-resolution reflection energy loss spectroscopy (HR-REELS), which was compared with the band gap profile calculated based on the auger depth profile. The band gap profile is a double-graded band gap as a function of in-depth. The calculated band gap obtained from the auger depth profile seems to be larger than that by HR-REELS. Calculated band gaps are to measure the average band gap of the spatially different varying compositions with respect to considering its void fraction. But, the results obtained using HR-REELS are to be affected by the low band gap (i.e., out of void) rather than large one (i.e., near void). Our findings suggest an analytical method to directly determine the band gap profile as function of in-depth.
Equivalent circuit analysis of radiative coupling in monolithic tandem solar cells
Authors: Lan Dongchen , Green Martin A.
Published: June 2015

As solar cell efficiency improves towards the Shockley-Queisser limit, so does the radiative efficiency of the cell. For tandem stacks of cells where energy conversion efficiency now exceeds 46%, radiative coupling between the cells is becoming increasingly important to consider in cell design, measurement, and performance prediction. We show how an equivalent circuit model can capture the complex radiative interactions between cells in such tandem stacks, allowing more insight into the impact on cell performance. The circuit's use is demonstrated by deriving results relevant to the critical step of eliminating coupling effects from measured cell spectral responses.
High upper critical fields of superconducting Ca10(Pt4As8)(Fe1.8Pt0.2As2)5 whiskers
Authors: Li Jun , Zhang Gufei , Hu Wei , Huang Ya , Ji Min , Sun Han-Cong , Zhou Xian-Jing , An De-Yue , Hao Lu-Yao , Zhu Qiang , Yuan Jie , Jin Kui , Guo Hong-Xuan , Fujita Daisuke , Hatano Takeshi , Yamaura Kazunari , Takayama-Muromachi Eiji , Wang Hua-Bing , Wu Pei-Heng , Vanacken Johan , Moshchalkov Victor V.
Published: June 2015

We investigated the upper critical fields of Ca10(Pt4As8)(Fe2–xPtxAs2)5 superconducting whiskers. The whiskers consist of several wire-like grains with diameter of around 200 nm, joined by grain boundaries whose misorientation angles are less than 5∘. The upper critical fields along c-axis and in ab-plane were observed as 49 T at 12 K and 50 T at 22 K, respectively, which can be extrapolated to ∼81 and ∼133 T at 0 K. The whisker demonstrated weak anisotropic factor and almost constant value of ∼2 below 15 K. The impressive transport properties of the whisker may find applications in fields like superconducting micro- and meso-structure systems.
Electric field induced short range to long range structural ordering and its influence on the Eu+3 photoluminescence in the lead-free ferroelectric Na1/2Bi1/2TiO3
Authors: Kalaskar Abhijeet , Rao Badari Narayana , Thomas Tiju , Ranjan Rajeev
Published: June 2015

Eu+3 was incorporated into the lattice of a lead-free ferroelectric Na1/2Bi1/2TiO3 (NBT) as per the nominal formula Na0.5Bi0.5−xEuxTiO3. This system was investigated with regard to the Eu+3 photoluminescence (PL) and structural behaviour as a function of composition and electric field. Electric field was found to irreversibly change the features in the PL spectra and also in the x-ray diffraction patterns below the critical composition x = 0.025. Detailed analysis revealed that below the critical composition, electric field irreversibly suppresses the structural heterogeneity inherent of the host matrix NBT and brings about a long range ferroelectric state with rhombohedral (R3c) distortion. It is shown that the structural disorder on the nano-scale opens a new channel for radiative transition which manifests as a new emission line branching off from the main 5D0→7F0 line along with a concomitant change in the relative intensity of the other crystal field induced Stark lines with different J values. The study suggests that Eu+3 luminescence can be used to probe the relative degree of field induced structural ordering in relaxor ferroelectrics and also in high performance piezoelectric alloys where electric field couples very strongly with the lattice and structural degrees of freedom.
Relation between surface and bulk electronic properties of Al doped ZnO films deposited at varying substrate temperature by radio frequency magnetron sputtering
Authors: Singh C. C. , Patel T. A. , Panda E.
Published: June 2015

In this study, a qualitative relationship between the surface and bulk electronic states for Al-doped ZnO (AZO) thin films (thickness < 260 nm) is established. To this end, AZO films were deposited on soda lime glass substrates by varying substrate temperature (Ts) from 303 K to 673 K in RF magnetron sputtering. All these AZO films are found to have grown in ZnO hexagonal wurtzite structure with strong (002) orientation of the crystallites and with an average transmittance of 84%–91% in the visible range. Room temperature scanning tunneling spectroscopy measurements reveal semiconducting behavior for the films deposited at Ts ≤ 373 K and semi-metallic behavior for those deposited at Ts > 373 K. Further, these films show two modes of electron tunneling, (a) direct tunneling at lower bias voltage and (b) FN tunneling at higher bias voltage, with transition voltage (Vtrans) shifting towards lower bias voltage (and thereby reducing the barrier height (Φ)) with increasing Ts. This is attributed to additional (local) density of states near the Fermi level of these AZO films because of higher carrier concentration (ne) at increased Ts. Thus, qualitatively, the behavior in both the local surface electronic states and bulk state electronic properties for these deposited AZO films are found to follow similar trends with increasing Ts. The variation in local barrier heights (indicative of the local surface electronic structures) across the AZO film surface is found to be smaller for the films deposited at Ts ≤ 373 K, where semiconducting behavior is observed and wider for the semi-metallic AZO films deposited at higher Ts > 373 K, indicating a larger inhomogeneity of local surface electronic properties at higher bulk carrier concentration.
Elastic response of mesoporous silicon to capillary pressures in the pores
Authors: Gor Gennady Y. , Bertinetti Luca , Bernstein Noam , Hofmann Tommy , Fratzl Peter , Huber Patrick
Published: June 2015

We study water adsorption-induced deformation of a monolithic, mesoporous silicon membrane traversed by independent channels of ∼8 nm diameter. We focus on the elastic constant associated with the Laplace pressure-induced deformation of the membrane upon capillary condensation, i.e., the pore-load modulus. We perform finite-element method (FEM) simulations of the adsorption-induced deformation of hexagonal and square lattices of cylindrical pores representing the membrane. We find that the pore-load modulus weakly depends on the geometrical arrangement of pores, and can be expressed as a function of porosity. We propose an analytical model which relates the pore-load modulus to the porosity and to the elastic properties of bulk silicon (Young's modulus and Poisson's ratio), and provides an excellent agreement with FEM results. We find good agreement between our experimental data and the predictions of the analytical model, with the Young's modulus of the pore walls slightly lower than the bulk value. This model is applicable to a large class of materials with morphologies similar to mesoporous silicon. Moreover, our findings suggest that liquid condensation experiments allow one to elegantly access the elastic constants of a mesoporous medium.
Robustness of plasmonic angular momentum confinement in cross resonant optical antennas
Authors: Klaer Peter , Razinskas Gary , Lehr Martin , Krewer Keno , Schertz Florian , Wu Xiao-Fei , Hecht Bert , Schönhense Gerd , Elmers Hans Joachim
Published: June 2015

Using a combination of photoemission electron microscopy and numerical simulations, we investigated the angular moment transfer in strongly enhanced optical near-fields of artificially fabricated optical antennas. The polarization dependence of the optical near-field enhancement has been measured in a maximum symmetric geometry, i.e., excitation by a normal incident planar wave. Finite-difference time-domain simulations for the realistic antenna geometries as determined by high-resolution electron microscopy reveal a very good agreement with experimental data. The agreement confirms that the geometrical asymmetries and inhomogeneities due to the nanoscale fabrication process preserve the circular polarization in the gap regions with strong near-field enhancement.
Continuous wave room temperature external ring cavity quantum cascade laser
Authors: Revin D. G. , Hemingway M. , Vaitiekus D. , Cockburn J. W. , Hempler N. , Maker G. T. , Malcolm G. P. A.
Published: June 2015

An external ring cavity quantum cascade laser operating at ∼5.2 μm wavelength in a continuous-wave regime at the temperature of 15 °C is demonstrated. Out-coupled continuous-wave optical powers of up to 23 mW are observed for light of one propagation direction with an estimated total intra-cavity optical power flux in excess of 340 mW. The uni-directional regime characterized by the intensity ratio of more than 60 for the light propagating in the opposite directions was achieved. A single emission peak wavelength tuning range of 90 cm−1 is realized by the incorporation of a diffraction grating into the cavity.
Dropout dynamics in pulsed quantum dot lasers due to mode jumping
Authors: Sokolovskii G. S. , Viktorov E. A. , Abusaa M. , Danckaert J. , Dudelev V. V. , Kolykhalova E. D. , Soboleva K. K. , Deryagin A. G. , Novikov I. I. , Maximov M. V. , Zhukov A. E. , Ustinov V. M. , Kuchinskii V. I. , Sibbett W. , Rafailov E. U. , Erneux T.
Published: June 2015

We examine the response of a pulse pumped quantum dot laser both experimentally and numerically. As the maximum of the pump pulse comes closer to the excited-state threshold, the output pulse shape becomes unstable and leads to dropouts. We conjecture that these instabilities result from an increase of the linewidth enhancement factor α as the pump parameter comes close to the excitated state threshold. In order to analyze the dynamical mechanism of the dropout, we consider two cases for which the laser exhibits either a jump to a different single mode or a jump to fast intensity oscillations. The origin of these two instabilities is clarified by a combined analytical and numerical bifurcation diagram of the steady state intensity modes.
High efficiency, full-color AlInGaN quaternary nanowire light emitting diodes with spontaneous core-shell structures on Si
Authors: Wang Renjie , Liu Xuedong , Shih Ishiang , Mi Zetian
Published: June 2015

We have developed AlInGaN quaternary core-shell nanowire heterostructures on Si substrate, wherein an In-rich core and an Al-rich shell were spontaneously formed during the epitaxial growth process. By varying the growth conditions, the emission wavelengths can be tuned from ∼430 nm to ∼630 nm. Such core-shell structures can largely suppress nonradiative surface recombination, leading to a significant enhancement of carrier lifetime from ∼0.2 ns to ∼2 ns. The resulting nanowire light emitting diodes can exhibit an output power exceeding 30 mW for a ∼1 × 1 mm2 non-packaged device at a current density of 100 A/cm2.
Effects of load voltage on voltage breakdown modes of electrical exploding aluminum wires in air
Authors: Wu Jian , Li Xingwen , Yang Zefeng , Wang Kun , Chao Youchuang , Shi Zongqian , Jia Shenli , Qiu Aici
Published: June 2015

The effects of the load voltage on the breakdown modes are investigated in exploding aluminum wires driven by a 1 kA, 0.1 kA/ns pulsed current in air. From laser probing images taken by laser shadowgraphy, schlieren imaging, and interferometry, the position of the shockwave front, the plasma channel, and the wire core edge of the exploding product can be determined. The breakdown mode makes a transition from the internal mode, which involves breakdown inside the wire core, to the shunting mode, which involves breakdown in the compressed air, with decreasing charging voltage. The breakdown electrical field for a gaseous aluminum wire core of nearly solid density is estimated to be more than 20 kV/cm, while the value for gaseous aluminum of approximately 0.2% solid density decreases to 15–20 kV/cm. The breakdown field in shunting mode is less than 20 kV/cm and is strongly affected by the vaporized aluminum, the desorbed gas, and the electrons emitted from the wire core during the current pause. Ohmic heating during voltage collapses will induce further energy deposition in the current channel and thus will result in different expansion speeds for both the wire core and the shockwave front in the different modes.
In-plane tunneling anisotropic magnetoresistance in (Ga,Mn)As/GaAs Esaki diodes in the regime of the excess current
Authors: Shiogai J. , Ciorga M. , Utz M. , Schuh D. , Kohda M. , Bougeard D. , Nojima T. , Weiss D. , Nitta J.
Published: June 2015

We investigate the angular dependence of the tunneling anisotropic magnetoresistance in (Ga,Mn)As/n-GaAs spin Esaki diodes in the regime where the tunneling process is dominated by the excess current through midgap states in (Ga,Mn)As. We compare it to similar measurements performed in the regime of band-to-band tunneling. Whereas the latter show biaxial symmetry typical for magnetic anisotropy observed in (Ga,Mn)As samples, the former is dominated by uniaxial anisotropy along the 〈110〉 axes.
A compact heat transfer model based on an enhanced Fourier law for analysis of frequency-domain thermoreflectance experiments
Authors: Ramu Ashok T. , Bowers John E.
Published: June 2015

A recently developed enhanced Fourier law is applied to the problem of extracting thermal properties of materials from frequency-domain thermoreflectance (FDTR) experiments. The heat transfer model comprises contributions from two phonon channels: one a high-heat-capacity diffuse channel consisting of phonons of mean free path (MFP) less than a threshold value, and the other a low-heat-capacity channel consisting of phonons with MFP higher than this value that travel quasi-ballistically over length scales of interest. The diffuse channel is treated using the Fourier law, while the quasi-ballistic channel is analyzed using a second-order spherical harmonic expansion of the phonon distribution function. A recent analysis of FDTR experimental data suggested the use of FDTR in deriving large portions of the MFP accumulation function; however, it is shown here that the data can adequately be explained using our minimum-parameter model, thus highlighting an important limitation of FDTR experiments in exploring the accumulation function of bulk matter.
Strong emission of terahertz radiation from nanostructured Ge surfaces
Authors: Kang Chul , Leem Jung Woo , Maeng Inhee , Kim Tae Heon , Lee Jong Seok , Yu Jae Su , Kee Chul-Sik
Published: June 2015

Indirect band gap semiconductors are not efficient emitters of terahertz radiation. Here, we report strong emission of terahertz radiation from germanium wafers with nanostructured surfaces. The amplitude of THz radiation from an array of nano-bullets (nano-cones) is more than five (three) times larger than that from a bare-Ge wafer. The power of the terahertz radiation from a Ge wafer with an array of nano-bullets is comparable to that from n-GaAs wafers, which have been widely used as a terahertz source. We find that the THz radiation from Ge wafers with the nano-bullets is even more powerful than that from n-GaAs for frequencies below 0.6 THz. Our results suggest that introducing properly designed nanostructures on indirect band gap semiconductor wafers is a simple and cheap method to improve the terahertz emission efficiency of the wafers significantly.
Temperature-dependent stability of energy storage properties of Pb0.97La0.02(Zr0.58Sn0.335Ti0.085)O3 antiferroelectric ceramics for pulse power capacitors
Authors: Liu Zhen , Chen Xuefeng , Peng Wei , Xu Chenhong , Dong Xianlin , Cao Fei , Wang Genshui
Published: June 2015

The dielectric properties and electrical hysteresis behaviors of Pb0.97La0.02(Zr0.58Sn0.335Ti0.085)O3 antiferroelectric (AFE) ceramics were investigated in this work with an emphasis on energy storage properties. Three phase transition points can be detected as temperature increases. AFE and paraelectric phases are found to coexist from 100 °C to 170 °C. The room temperature recoverable energy density is 1.37 J/cm3 at 8.6 kV/mm. With increasing temperature (from 20 °C to 100 °C) and frequency (from 0.01 to 100 Hz) under 8.6 kV/mm, the variation of recoverable energy density was less than 15%, all higher than 1.2 J/cm3. All the corresponding energy efficiencies were no less than 75%. The high energy density, high energy efficiency, and their weak dependence on temperature and frequency during a wide scope indicate that these antiferroelectric ceramics are quite promising to be used for pulse power capacitors applications.
Widely tunable terahertz source based on intra-cavity frequency mixing in quantum cascade laser arrays
Authors: Jiang Aiting , Jung Seungyong , Jiang Yifan , Vijayraghavan Karun , Kim Jae Hyun , Belkin Mikhail A.
Published: June 2015

We demonstrate a compact monolithic terahertz source continuously tunable from 1.9 THz to 3.9 THz with the maximum peak power output of 106 μW at 3.46 THz at room temperature. The source consists of an array of 10 electrically tunable quantum cascade lasers with intra-cavity terahertz difference-frequency generation. To increase fabrication yield and achieve high THz peak power output in our devices, a dual-section current pumping scheme is implemented using two electrically isolated grating sections to independently control gain for the two mid-IR pumps.
New, Homochiral Synthons Obtained through Simple Manipulations of Enzymatically Derived 3-Halo-cis-1,2-dihydrocatechols
Authors: White Lorenzo V. , Lan Ping , Schwartz Brett D. , Willis Anthony C. , Banwell Martin G.
Published: June 2015

The bromoepoxide 5a, which is obtained from the homochiral and enzymatically derived cis-1,2-dihydrocatechol 1a, is readily and efficiently transformed into either isomer 8a or the corresponding methoxymethyl-ether 2a. Though both of these products can be fully characterized, they are somewhat unstable, with the former being converted into the crystalline enone 3a on standing and the latter readily participating in a Diels–Alder cycloaddition reaction with the potent dienophile N-phenyl-1,2,4-triazoline-3,5-dione to give adduct 7a. The single-crystal X-ray structures of compounds 3a and 7a are reported. Using the related chemistry the chloro-analogue, 3b, of enone 3a can be obtained.
Structural Reevaluation of the Crystalline Methylenedigallic Acids
Authors: Marcuccio Sebastian M. , Turner Kathleen A.
Published: June 2015

Analysis of the products of the previously reported conditions for the preparation of crystalline methylenedigallic acids from gallic acid has revealed that the water-insoluble acid is a tetrahomodioxacalix[4]arene and the water-soluble acid is a trimeric species.
Thermolytic degradation of methylmethionine and implications for its role in DMS and MeCl formation in hypersaline environments
Authors: Mulder Ines , Krause Torsten , Sattler Tobias , Tubbesing Christoph , Studenroth Sabine , Bukowski Krzysztof , Atlas Elliot , Schöler Heinz F.
Published: June 2015

Environmental context Methyl chloride and dimethyl sulfide are important atmospheric trace gases, but their biogeochemical contributions to the atmosphere are not fully understood. The amino acid derivative methyl methionine has been hypothesised to be a precursor of these two atmospheric gases, especially in drying salt-lake environments. We found methyl chloride and dimethyl sulfide in salt crystals and soil samples of hypersaline lakes, suggesting that a thermal decay of methyl methionine could be one of the formation mechanisms responsible. Abstract Volatile organic halocarbons (VOXs) and volatile organosulfur compounds (VOSCs) play an important role in the chemical processes of the lower atmosphere. However, biogeochemical release mechanisms from terrestrial environments are complex and the current knowledge of the origin and fluxes of these compounds is incomplete. This study presents data from worldwide sampling campaigns to hypersaline salt lakes to investigate terrestrial sources for atmospheric VOXs and VOSCs. The hypothesis was tested if methionine or methylmethionine could potentially serve as a precursor for methyl chloride and dimethyl sulfide formation in salt-lake environments. Next to methyl chloride, emissions from hypersaline soil samples incubated in headspace vials showed an array of VOSCs including dimethylsulfide and dimethyldisulfide. Additionally, methyl chloride and dimethyl sulfide were released from fluid inclusions of halite crystals after grinding and purge-and-trap headspace gas chromatography–mass spectrometry analysis. An abiotic mechanism for their formation is conceivable owing to the fast response of emission on heating freeze-dried samples at 40°C. Furthermore, the compounds trapped in fluid inclusions of halite crystals correspond to those compounds originally formed in the immediately subjacent soils. Based on the thermolytic degradation of methylmethionine, the activation energies for methyl chloride and dimethyl sulfide are calculated from their Arrhenius plots. Additionally, structurally related substances were analysed and a degradation mechanism is postulated. Results indicate that thermolytic processes could play an important role in salt-lake environments on desiccation.
Vertical distribution of BrO in the boundary layer at the Dead Sea
Authors: Holla Robert , Schmitt Stefan , Frieß Udo , Pöhler Denis , Zingler Jutta , Corsmeier Ulrich , Platt Ulrich
Published: June 2015

Environmental context
Reactive halogen species affect chemical processes in the troposphere in many ways. The reactive bromine species bromine monoxide (BrO) is found in high concentrations at the Dead Sea, but processes for its formation and its spatial distribution are largely unknown. Information on the vertical distribution of BrO at the Dead Sea obtained in this work may give insight into the processes leading to BrO release and its consequences.

Abstract
We present results of multi-axis differential optical absorption spectroscopy (MAX‐DOAS) and long‐path DOAS (LP‐DOAS) measurements from two measurement campaigns at the Dead Sea in 2002 and 2012. The special patterns of its dynamics and topography in combination with the high salt and especially bromide content of its water lead to the particular large atmospheric abundances of more than 100 ppt BrO close to the ground and in several hundred meters above ground level. We conclude that vertical transport barriers induced by the special dynamics in the Dead Sea Valley lead to an accumulation of aerosol and reactive bromine species. This occurs in situations of weak synoptic winds and of mountain induced thermal circulations. Thus BrO release strongly depends on the topography and local and meso-scale meteorology. In case of strong zonal winds, the Dead Sea valley is flushed and high BrO levels cannot accumulate. NO2 levels below 1–2 ppb seem to be a prerequisite for a high BrO production. We assume that at least a part of the missing NO2 might be converted to BrONO2 leading to a deposition of nitrate within the aerosol and acting as a reservoir for reactive bromine. From these measurements, it was possible for the first time to simultaneously retrieve vertical profiles of aerosols, BrO and NO2 and gain also information on the distribution at the Dead Sea, allowing for a thorough characterization of the chemical processes leading to halogen release in the context of the special atmospheric dynamics in the Dead Sea Valley.
New particle formation above a simulated salt lake in aerosol chamber experiments
Authors: Kamilli K. A. , Ofner J. , Lendl B. , Schmitt-Kopplin P. , Held A.
Published: June 2015

Environmental context
Deforestation in Western Australia beginning in the mid-19th century led to a considerable change of the land surface, and Western Australia is now suffering more often from droughts. Particle formation induced by salt lakes has been identified as a potential control factor for changed precipitation patterns. This study aims to determine key factors involved in the particle formation process by simulating a simplified salt lake in an aerosol chamber in the laboratory.

Abstract
In recent field experiments, particle formation has been observed above salt lakes in Western Australia and related to changes in regional precipitation patterns. This work investigates the particle formation potential above a simulated salt lake in aerosol chamber experiments under various conditions. The salt lake mixture comprised fixed concentrations of NaBr, NaCl and Na2SO4, and varying concentrations of FeSO4 and FeCl3. Further, an organic mixture of 1,8-cineol and limonene was added under dark and light conditions. Both the presence of organic compounds and of light were found to be essential for new particle formation in our experiments. There were clear indications for conversion of FeII to FeIII, which suggests a Fenton-like reaction mechanism in the system. Contrary to the idea that a Fenton-like reaction mechanism might intensify the oxidation of organic matter, thus facilitating secondary organic aerosol formation, the observed particle formation started later and with lower intensity under elevated FeII concentrations. The highest particle number concentrations were observed when excluding FeII from the experiments. Chemical analysis of the formed aerosol confirmed the important role of the Fenton-like reaction for particle formation in this study. Ultrahigh-resolution mass spectrometry and Raman spectroscopy provide analytical proof for the formation of organosulfates and halogenated organic compounds in the experiments presented. Even though halogens and organic precursors are abundant in these experimental simulations, halogen-induced organic aerosol formation exists but seems to play a minor overall role in particle formation.
Migration Timing of Adult Chinook Salmon into the Togiak River, Alaska, Watershed: Is There Evidence for Stock Structure?
Authors: Clark Sydney C. , Tanner Theresa L. , Sethi Suresh A. , Bentley Kale T. , Schindler Daniel E.
Published: June 2015

Variation in the timing of migration to freshwaters to spawn is one important dimension of the life history variation within individual salmon stocks. That variable has important implications for developing sustainable fisheries that simultaneously exploit multiple populations within the same geographic area. We examined the variation in migration timing of adult Chinook Salmon Oncorhynchus tshawytscha within the Togiak River system of southwest Alaska to determine whether fish that spawned in different habitats migrated into freshwater from the ocean at different times. In particular, we evaluated whether there were watershed‐wide effects of body size, sex, spawning location, and year on the timing of spawning‐run migration into the Togiak River. Migration data and spawning fate were collected using radiotelemetry and analyzed with mixed effects models to account for among‐year variation in migration timing across the 4 years of the study. We found that migration timing of Chinook Salmon in the Togiak watershed is segregated by spawning location and sex and is consistent across body sizes and years. Fish that spawned higher in the watershed had a tendency to enter freshwater earlier than fish that spawned lower in the watershed and in the main stem of the river. Our results indicate clear stock structure in the migration of spawning Chinook Salmon to the Togiak River watershed, suggesting that it is important to distribute harvest over the entire distribution of Chinook Salmon run timing to minimize the risk of overexploiting certain components of the stock complex.
Evidence of Countergradient Variation in Growth of Spotted Gars from Core and Peripheral Populations
Authors: David Solomon R. , Kik Richard S. , Diana James S. , Rutherford Edward S. , Wiley Michael J.
Published: June 2015

Peripheral populations occupy the edge of a species' range and may exhibit adaptations to potentially “harsher” marginal environments compared with core populations. The peripheral population of Spotted Gar Lepisosteus oculatus in the Great Lakes basin represents the northern edge of the species' range and is completely disjunct from the core Mississippi River basin population. Age‐0 Spotted Gars from the peripheral population experience a growing season approximately half that of the core population but reach similar sizes by winter, suggesting potential for countergradient variation in growth, i.e. an evolutionary response to an environmental gradient such as latitude to compensate for the usual phenotypic effect of that gradient. In this study we used two common garden experiments to investigate potential countergradient variation in growth of young‐of‐year Spotted Gars from peripheral populations in comparison with those from core populations. Our first experiment showed that in a common environment under temperatures within the first growing season (22–24°C), Spotted Gars from the peripheral population had significantly higher growth rates than those from the core population. Final Spotted Gar weight–length ratio was also higher in the peripheral versus core population. In our second experiment, under three temperature treatments (16, 23, and 30°C), maximum growth occurred at the highest temperature, whereas growth ceased at the lowest temperature for both populations. These results suggest that important genetic and physiological differences could exist between the two population groups, consistent with countergradient variation. Our findings indicate that countergradient growth variation can occur even in relatively slowly evolving fishes, such as gars (family Lepisosteidae), and that protection of peripheral populations should be a key component of fish conservation planning.
Development and function of follicular helper T cells
Authors: Ise Wataru
Published: June 2015

Most currently available vaccines rely on the induction of long-lasting protective humoral immune responses by memory B cells and plasma cells. Antibody responses against most antigens require interactions between antigen-specific B cells and CD4+ T cells. Follicular helper T cells (TFH cells) are specialized subset of T cells that provide help to B cells and are essential for germinal center formation, affinity maturation, and the development of high-affinity antibodies. TFH-cell differentiation is a multistage process involving B-cell lymphoma 6 and other transcription factors, cytokines, and costimulation through inducible costimulator (ICOS) and several other molecules. This article reviews recent advances in our understanding of TFH cell biology, including their differentiation, transcriptional regulation, and function.
Membrane potential and Ca2+ concentration dependence on pressure and vasoactive agents in arterial smooth muscle: A model
Authors: Karlin Arthur
Published: June 2015

Arterial smooth muscle (SM) cells respond autonomously to changes in intravascular pressure, adjusting tension to maintain vessel diameter. The values of membrane potential (Vm) and sarcoplasmic Ca2+ concentration (Cain) within minutes of a change in pressure are the results of two opposing pathways, both of which use Ca2+ as a signal. This works because the two Ca2+-signaling pathways are confined to distinct microdomains in which the Ca2+ concentrations needed to activate key channels are transiently higher than Cain. A mathematical model of an isolated arterial SM cell is presented that incorporates the two types of microdomains. The first type consists of junctions between cisternae of the peripheral sarcoplasmic reticulum (SR), containing ryanodine receptors (RyRs), and the sarcolemma, containing voltage- and Ca2+-activated K+ (BK) channels. These junctional microdomains promote hyperpolarization, reduced Cain, and relaxation. The second type is postulated to form around stretch-activated nonspecific cation channels and neighboring Ca2+-activated Cl− channels, and promotes the opposite (depolarization, increased Cain, and contraction). The model includes three additional compartments: the sarcoplasm, the central SR lumen, and the peripheral SR lumen. It incorporates 37 protein components. In addition to pressure, the model accommodates inputs of α- and β-adrenergic agonists, ATP, 11,12-epoxyeicosatrienoic acid, and nitric oxide (NO). The parameters of the equations were adjusted to obtain a close fit to reported Vm and Cain as functions of pressure, which have been determined in cerebral arteries. The simulations were insensitive to ±10% changes in most of the parameters. The model also simulated the effects of inhibiting RyR, BK, or voltage-activated Ca2+ channels on Vm and Cain. Deletion of BK β1 subunits is known to increase arterial–SM tension. In the model, deletion of β1 raised Cain at all pressures, and these increases were reversed by NO.
On the existence and uniqueness of global solutions for the KdV equation with quasi-periodic initial data
Authors: Damanik David , Goldstein Michael
Published: June 2015

We consider the KdV equation∂tu+∂x3u+u∂xu=0\partial _t u +\partial ^3_x u +u\partial _x u=0with quasi-periodic initial data whose Fourier coefficients decay exponentially and prove existence and uniqueness, in the class of functions which have an expansion with exponentially decaying Fourier coefficients, of a solution on a small interval of time, the length of which depends on the given data and the frequency vector involved. For a Diophantine frequency vector and for small quasi-periodic data (i.e., when the Fourier coefficients obey|c(m)|≤εexp⁡(−κ0|m|)|c(m)| \le \varepsilon \exp (-\kappa _0 |m|)withε>0\varepsilon > 0sufficiently small, depending onκ0>0\kappa _0 > 0and the frequency vector), we prove global existence and uniqueness of the solution. The latter result relies on our recent work [Publ. Math. Inst. Hautes Études Sci.119(2014) 217] on the inverse spectral problem for the quasi-periodic Schrödinger equation.
Case 4
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Venous Access section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 5
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Venous Access section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 7
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Biopsy section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 9
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Biopsy section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 17
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Biopsy section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 19
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Biopsy section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 21
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Ablation section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 22
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Ablation section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 28
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Embolization section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 38
Authors: Covey Anne M. , Pua Bradley B. , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Embolization section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 50
Authors: Covey Anne M. , Pua Bradley B. , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Genitourinary Intervention section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 58
Authors: Covey Anne M. , Pua Bradley B. , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Gastrointestinal/Biliary Intervention section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 59
Authors: Covey Anne M. , Pua Bradley B. , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Gastrointestinal/Biliary Intervention section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 62
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Venous Intervention section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 68
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Venous Intervention section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 80
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Arterial Intervention section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 89
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Arterial Intervention section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 91
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Arterial Intervention section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 94
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Drainage section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.
Case 98
Authors: Covey Anne M. , Pua Bradley B , Aguado Allison , Madoff David C.
Published: June 2015

This is a case from the Drainage section of Interventional Radiology Cases. The specific content of each case and its diagnosis are necessarily hidden from this abstract. Each case contains case history, followed immediately by the diagnosis, which is supported with findings, differential diagnosis, teaching points, management, and further reading suggestions.