ALBERT

Beschreibung: The ongoing disintegration of large ice shelf parts in Antarctica raise the need for a better understanding of the physical processes that trigger critical crack growth in ice shelves. Finite elements in combination with configurational forces facilitate the analysis of single surface fractures in ice under various boundary conditions and material parameters. The principles of linear elastic fracture mechanics are applied to show the strong influence of different depth dependent functions for the density and the Young’s modulus on the stress intensity factor KI at the crack tip. Ice, for this purpose, is treated as an elastically compressible solid and the conse- quences of this choice in comparison to the predominant in- compressible approaches are discussed. The computed stress intensity factors KI for dry and water filled cracks are com- pared to critical values KIc from measurements that can be found in literature.

Beschreibung: Permafrost is one of the essential climate variables addressed by the Global Terrestrial Observing System (GCOS). Remote sensing data provide area-wide monitoring of e.g. surface temperatures or soil surface status (frozen or thawed state) in the Arctic and Subarctic, where ground data collection is difficult and restricted to local measurements at few monitoring sites. The task of the ESA Data User Element (DUE) Permafrost project is to build-up an Earth observation service for northern high-latitudinal permafrost applications with extensive involvement of the international permafrost research community (www.ipf.tuwien.ac.at/permafrost). The satellite-derived DUE Permafrost products are Land Surface Temperature, Surface Soil Moisture, Surface Frozen and Thawed State, Digital Elevation Model (locally as remote sensing product and circumpolar as non-remote sensing product) and Subsidence, and Land Cover. Land Surface Temperature, Surface Soil Moisture, and Surface Frozen and Thawed State will be provided for the circumpolar permafrost area north of 55° N with 25 km spatial resolution. In addition, regional products with higher spatial resolution were developed for five case study regions in different permafrost zones of the tundra and taiga (Laptev Sea [RU], Central Yakutia [RU], Western Siberia [RU], Alaska N-S transect, [US] Mackenzie River and Valley [CA]). This study shows the evaluation of two DUE Permafrost regional products, Land Surface Temperature and Surface Frozen and Thawed State, using freely available ground truth data from the Global Terrestrial Network of Permafrost (GTN-P) and monitoring data from the Russian-German Samoylov research station in the Lena River Delta (Central Siberia, RU). The GTN-P permafrost monitoring sites with their position in different permafrost zones are highly qualified for the validation of DUE Permafrost remote sensing products. Air and surface temperatures with high-temporal resolution from eleven GTN-P sites in Alaska and four sites in Siberia were used to match up LST products. Daily average GTN-P borehole- and air temperature data for three Alaskan and six Western Siberian sites were used to evaluate surface frozen and thawed. First results are promising and demonstrate the great benefit of freely available ground truth databases for remote sensing products.

Beschreibung: Here we present results of the first comprehensive study of sulphur compounds and methane in the oligotrophic tropical West Pacific Ocean. The concentrations of dimethylsuphide (DMS), dimethylsulphoniopropionate (DMSP), dimethylsulphoxide (DMSO), and methane (CH4), as well as various phytoplankton marker pigments in the surface ocean were measured along a north-south transit from Japan to Australia in October 2009. DMS (0.9 nmol l−1), dissolved DMSP (DMSPd, 1.6 nmol l−1) and particulate DMSP (DMSPp, 2 nmol l−1) concentrations were generally low, while dissolved DMSO (DMSOd, 4.4 nmol l−1) and particulate DMSO (DMSOp, 11.5 nmol l−1) concentrations were comparably enhanced. Positive correlations were found between DMSO and DMSP as well as DMSP and DMSO with chlorophyll a, which suggests a similar source for both compounds. Similar phytoplankton groups were identified as being important for the DMSO and DMSP pool, thus, the same algae taxa might produce both DMSP and DMSO. In contrast, phytoplankton seemed to play only a minor role for the DMS distribution in the western Pacific Ocean. The observed DMSPp : DMSOp ratios were very low and seem to be characteristic of oligotrophic tropical waters representing the extreme endpoint of the global DMSPp : DMSOp ratio vs. SST relationship. It is most likely that nutrient limitation and oxidative stress in the tropical West Pacific Ocean triggered enhanced DMSO production leading to an accumulation of DMSO in the sea surface. Positive correlations between DMSPd and CH4, as well as between DMSO (particulate and total) and CH4, were found along the transit. We conclude that both DMSP and DMSO serve as substrates for methanogenic bacteria in the western Pacific Ocean.

Beschreibung: Dynamical processes during the formation phase of the Arctic stratospheric vortex in autumn (from September to December) can introduce considerable interannual variability in the amount of ozone that is incorporated into the vortex. Chemistry in autumn tends to remove part of this variability because ozone relaxes towards equilibrium. As a quantitative measure of how important dynamical variability during vortex formation is for the winter ozone abundances above the Arctic we analyze which fraction of an ozone anomaly induced during vortex formation persists until early winter (3 January). The work is based on the Lagrangian Chemistry Transport Model ATLAS. In a case study, model runs for the winter 1999–2000 are used to assess the fate of an ozone anomaly artificially introduced during the vortex formation phase on 16 September. The runs provide information about the persistence of the induced ozone anomaly as a function of time, potential temperature and latitude. The induced ozone anomaly survives longer inside the polar vortex compared to outside the vortex. Half of the initial perturbation survives until 3 January at 540 K inside the polar vortex, with a rapid fall off towards higher levels, mainly due to NOx induced chemistry. Above 750 K the signal falls to values below 0.5%. Hence, dynamically induced ozone variability from the early vortex formation phase cannot significantly contribute to early winter variability above 750 K. At lower levels increasingly larger fractions of the initial perturbation survive, reaching 90% at 450 K. In this vertical range dynamical processes during the vortex formation phase are crucial for the ozone abundance in early winter.

Beschreibung: Steven D. Granz, Katayun Barmak, and Mark H. Kryder A comparison was made of FePt-B and FePt-B-Ag thin films having different volume contents of boron, which were RF sputtered with in-situ heating at 425575 degrees C onto Si substrates with 20 nm thick (002) MgO. By introducing boron into FePt and varying the sputtering conditions, films with grain ... [J. Appl. Phys. 111, 07B709 (2012)] published Thu Mar 8, 2012.

Beschreibung: M. S. Khalil, M. J. A. Stoutimore, F. C. Wellstood, and K. D. Osborn We examine the transmission through nonideal microwave resonant circuits. The general analytical resonance line shape is derived for both inductive and capacitive coupling with mismatched input and output transmission impedances, and it is found that, for certain non-ideal conditions, the line shape ... [J. Appl. Phys. 111, 054510 (2012)] published Thu Mar 8, 2012.

Beschreibung: Julia Wagner, Mark Gruber, Andreas Wilke, Yuya Tanaka, Katharina Topczak et al. We investigate different parameters influencing the occurrence of s-shaped current voltage (j-V) characteristics in planar heterojunction organic solar cells. It is shown how substrate modification, purity of the active organic material as well as variation of the top contact can affect the shape of ... [J. Appl. Phys. 111, 054509 (2012)] published Thu Mar 8, 2012.

Beschreibung: Q. An, W. Z. Han, S. N. Luo, T. C. Germann, D. L. Tonks et al. We investigate with molecular dynamics the dynamic response of Cu bicrystals with a special asymmetric grain boundary (GB), (111)//(112), and its dependence on the loading directions. Shock loading is applied along the GB normal either from the left or right to the GB. Due to the structure asymmetry ... [J. Appl. Phys. 111, 053525 (2012)] published Thu Mar 8, 2012.

Beschreibung: S. Y. Liu, C. M. Zhen, Y. Z. Li, C. F. Pan, H. J. Zhou et al. Room temperature ferromagnetism has been observed in hydrogenated N-doped amorphous carbon films (a-CN:H) prepared by plasma enhanced chemical vapor deposition. The magnetization of the films changed depending on the ratio (R) of the flow rate of nitrogen to that of methane during deposition and on ... [J. Appl. Phys. 111, 053922 (2012)] published Thu Mar 8, 2012.

Beschreibung: H. Xiang and K. Komvopoulos A contact-mode surface micromachine consisting of polycrystalline silicon was used to study the effect of repetitive impact loading on the evolution of adhesion at sidewall contact interfaces under different conditions of contact load, ambient pressure, and relative humidity. All micromachines demon ... [J. Appl. Phys. 111, 054507 (2012)] published Thu Mar 8, 2012.

Beschreibung: K. H. Matlack, J. J. Wall, J.-Y. Kim, J. Qu, L. J. Jacobs et al. Nonlinear ultrasound was used to monitor radiation damage in two reactor pressure vessel (RPV) steels. The microstructural changes associated with radiation damage include changes in dislocation density and the formation of precipitates, and nonlinear ultrasonic waves are known to be sensitive to su ... [J. Appl. Phys. 111, 054911 (2012)] published Thu Mar 8, 2012.

Beschreibung: Jin Fang, Yi Huang, Christopher M. Lew, Yushan Yan, and Laurent Pilon This paper reports the temperature dependent cross-plane thermal conductivity of pure silica zeolite (PSZ) MFI and MEL thin films measured using the 3omega method between 30 and 315 K. PSZ MFI thin films were b-oriented, fully crystalline, and had a 33% microporosity. PSZ MEL thin films consisted of ... [J. Appl. Phys. 111, 054910 (2012)] published Thu Mar 8, 2012.

Beschreibung: K. Ozdogan, M. Upadhyay Kahaly, S. R. Sarath Kumar, H. N. Alshareef, and U. Schwingenschlogl We study epitaxial SrTiO interfaced with Nb-doped SrTiNbO (x = 0, 0.125, 0.25, 0.375, and 0.5) by full-potential density functional theory. From the electronic band structures obtained by our ab-initio calculations we determine the dependence of the induced metallicity on the Nb concentration. We ob ... [J. Appl. Phys. 111, 054313 (2012)] published Thu Mar 8, 2012.

Beschreibung: Jianbo Hu, Kouhei Ichiyanagi, Hiroshi Takahashi, Hiroaki Koguchi, Takeaki Akasaka et al. The high-pressure phase stability of the metastable tetragonal zirconia is still under debate. The transition dynamics of shocked YO (3 mol. %) stabilized tetragonal zirconia ceramics under laser-shock compression has been directly studied using nanosecond time-resolved x-ray diffraction. The marten ... [J. Appl. Phys. 111, 053526 (2012)] published Thu Mar 8, 2012.

Beschreibung: P. R. Coxon, M. Newman, M. R. C. Hunt, N. O'Farrell, B. R. Horrocks et al. Silicon nanocrystals (SiNCs) modified with 18-mer DNA oligonucleotides have been studied by X-ray excited optical luminescence (XEOL) and X-ray absorption spectroscopy (XAS) in photoluminescence yield (PLY) and total electron yield (TEY) modes. Luminescence spectra from the DNA-modified SiNCs under ... [J. Appl. Phys. 111, 054311 (2012)] published Thu Mar 8, 2012.

Beschreibung: Jim Long Her, Yasuhiro H. Matsuda, Motohiro Nakano, Yasuhiro Niwa, and Yasuhiro Inada X-ray absorption near-edge structure (XANES) spectra of Mn in a spin-crossover compound, [Mn(taa)], was studied in pulsed high magnetic fields up to 37 T. The significant changes in the XANES spectra, related to the spin-crossover from the low-spin (LS) state to high-spin (HS) state, were found to b ... [J. Appl. Phys. 111, 053921 (2012)] published Thu Mar 8, 2012.

Beschreibung: B. Berini, A. Fouchet, E. Popova, J. Scola, Y. Dumont et al. Determining phase transitions has always been a great challenge in material science due to their important fundamental and technological aspects. Recently, iron-based perovskites (RFeO), exhibiting phase transitions at high temperatures, have attracted much interest for their functional properties a ... [J. Appl. Phys. 111, 053923 (2012)] published Thu Mar 8, 2012.

Beschreibung: C. Lazzaroni and P. Chabert A global (volume-averaged) model of the self-pulsing regime of micro-hollow cathode discharges working in argon gas is proposed. The power balance is done using an equivalent circuit model of the discharge that allows the current and voltage dynamics to be calculated. The fraction of the total power ... [J. Appl. Phys. 111, 053305 (2012)] published Thu Mar 8, 2012.

Beschreibung: M. Koubaa, T. Dammak, D. Garrot, M. Castro, E. Codjovi et al. The thermal properties of the perovskite slab alkylammonium lead iodide (FCHCHNH)[PbI] are investigated using spectroscopic ellipsometry, differential scanning calorimetry, photoluminescence, and Raman spectroscopy. The spectroscopic ellipsometry, performed in the heating mode, clearly evidenced the ... [J. Appl. Phys. 111, 053521 (2012)] published Thu Mar 8, 2012.

Beschreibung: X. M. Dou, B. Q. Sun, D. S. Jiang, H. Q. Ni, and Z. C. Niu The temperature-dependent electron spin relaxation of positively charged excitons in a single InAs quantum dot was measured by time-resolved photoluminescence spectroscopy at zero applied magnetic fields. The experimental results show that the electron-spin relaxation is clearly divided into two dif ... [J. Appl. Phys. 111, 053524 (2012)] published Thu Mar 8, 2012.

Beschreibung: Y. Zhang, N. Mattern, and J. Eckert We have studied the phase formation of CuZr liquids with x = 0, 0.5, 1, 2, 5, 10, and 25 using molecular dynamics simulations, respectively, in order to find a direct relationship between the atomic structures and the glass forming abilities (GFAs). The difference among the critical cooling rates ha ... [J. Appl. Phys. 111, 053520 (2012)] published Thu Mar 8, 2012.

Beschreibung: Antonio Faraone, Kunlun Hong, Larry R. Kneller, Michael Ohl, and John R. D. Copley The coherent dynamics of a typical fragile glass former, meta-toluidine, was investigated at the molecular level using quasielastic neutron scattering, with time-of-flight and neutron spin echo spectrometers. It is well known that the static structure factor of meta-toluidine shows a prepeak origina ... [J. Chem. Phys. 136, 104502 (2012)] published Thu Mar 8, 2012.

Beschreibung: Minglong Jiang, Qun Zeng, Tingting Zhang, Mingli Yang, and Koblar Alan Jackson The lowest-energy isomers of Cu clusters for N = 2030 are identified using an unbiased search algorithm and density functional theory calculations. The low-energy structures over this size range are dominated by those based on a 13-atom icosahedral (I) core and a 19-atom double icosahedron (DI) core ... [J. Chem. Phys. 136, 104501 (2012)] published Thu Mar 8, 2012.

Beschreibung: Kyousuke Yoshida, Koichi Iwata, Yoshio Nishiyama, Yoshifumi Kimura, and Hiro-o Hamaguchi Vibrational cooling rate of the first excited singlet (S) state of trans-stilbene and bulk thermal diffusivity are measured for seven room temperature ionic liquids, CmimTfN, CmimTfN, CmimPF, CmimTfN, CmimTfN, CmimTfN, and bmpyTfN. Vibrational cooling rate measured with picosecond time-resolved Rama ... [J. Chem. Phys. 136, 104504 (2012)] published Thu Mar 8, 2012.

Beschreibung: Ayse Arslanargin and Thomas L. Beck Free energy partitioning analysis is employed to explore the driving forces for ions interacting with the water liquid-vapor interface using recently optimized point charge models for the ions and SPC/E water. The Na and I ions are examined as an example kosmotrope/chaotrope pair. The absolute hydra ... [J. Chem. Phys. 136, 104503 (2012)] published Thu Mar 8, 2012.

Beschreibung: Taweetham Limpanuparb, Joshua W. Hollett, and Peter M. W. Gill We discuss the efficient computation of the auxiliary integrals that arise when resolutions of two-electron operators (specifically, the Coulomb operator [T. Limpanuparb, A. T. B. Gilbert, and P. M. W. Gill, J. Chem. Theory Comput. 7, 830 (2011)] and the long-range Ewald operator [T. Limpanuparb and ... [J. Chem. Phys. 136, 104102 (2012)] published Thu Mar 8, 2012.

Beschreibung: Sarom S. Leang, Federico Zahariev, and Mark S. Gordon The performance of 24 density functionals, including 14 meta-generalized gradient approximation (mGGA) functionals, is assessed for the calculation of vertical excitation energies against an experimental benchmark set comprising 14 small- to medium-sized compounds with 101 total excited states. The ... [J. Chem. Phys. 136, 104101 (2012)] published Thu Mar 8, 2012.

Beschreibung: Longjiu Cheng (程龙玖) Experiments revealed that small boron cluster anions and cations are (quasi-)planar. For neutral boron cluster, (quasi-)planar motifs are also suggested to be global minimum by many theoretical studies, and a structural transformation from quasi-planar to double-ring tubular structures occurs at B. ... [J. Chem. Phys. 136, 104301 (2012)] published Thu Mar 8, 2012.

Beschreibung: Paul Baird and Mohammad Wehbe Given a Riemannian 3-manifold (M, g) endowed with a unit vector field U that is tangent to a conformal foliation, we require that the pair extend to a space-time ([script M],[script G]) endowed with a space-like unit vector field U in such a way that U simultaneously generates null geodesics and is ... [J. Math. Phys. 53, 032504 (2012)] published Thu Mar 8, 2012.

Beschreibung: Intercomparison of two meteorological limited area models for quantitative precipitation forecast verification Natural Hazards and Earth System Science, 12, 591-606, 2012 Author(s): E. Oberto, M. Milelli, F. Pasi, and B. Gozzini The demand for verification of numerical models is still very high, especially for what concerns the operational Quantitative Precipitation Forecast (QPF) used, among others, for evaluating the issuing of warnings to the population. In this study, a comparative verification of the QPF, predicted by two operational Limited Area Models (LAMs) for the Italian territory is presented: COSMO-I7 (developed in the framework of the COSMO Consortium) and WRF-NMM (developed at NOAA-NCEP). The observational dataset is the precipitation recorded by the high-resolution non-GTS rain gauges network of the National Civil Protection Department (NCPD) over two years (2007–2008). Observed and forecasted precipitation have been treated as areal quantity (areal average of the values accumulated in 6 and 24 h periods) over the 102 "warning areas", defined by the NCPD both for administrative and hydrological purposes. Statistics are presented through a series of conventional indices (BIAS, POD and POFD) and, in addition, the Extreme Dependency Score (EDS) and the Base Rate (BS or 1-BS) have been used for keeping into account the vanishing of the indices as the events become rare. Results for long-period verification (the whole 2 yr) with increasing thresholds, seasonal trend (3 months period), diurnal error cycle and error maps, are presented. Results indicate that WRF has a general tendency of QPF overestimation for low thresholds and underestimation for higher ones, while COSMO-I7 tends to overestimate for all thresholds. Both models show a seasonal trend, with a bigger overestimation during summer and spring, while during autumn and winter the models tend to be more accurate.

Beschreibung: Ph. Traore and A. T. Perez Two-dimensional numerical simulations are carried out to examine the problem of transient electroconvection stability of dielectric liquids subjected to unipolar injection. The entire set of electrohydrodynamics equations associated with the electroconvective phenomena that occur in a layer of a die ... [Phys. Fluids 24, 037102 (2012)] published Thu Mar 8, 2012.

Beschreibung: Jianqiang Han, Xiaofei Wang, Tianhong Yan, Yan Li, and Meixuan Song Microcantilever with integrated piezoresistor has been applied to in situ surface stress measurement in the field of biochemical sensors. It is well known that piezoresistive cantilever-based sensors are sensitive to ambient temperature changing due to highly temperature-dependent piezoresistive eff ... [Rev. Sci. Instrum. 83, 035002 (2012)] published Thu Mar 8, 2012.

Beschreibung: Pore formation during dehydration of a polycrystalline gypsum sample observed and quantified in a time-series synchrotron X-ray micro-tomography experiment Solid Earth, 3, 71-86, 2012 Author(s): F. Fusseis, C. Schrank, J. Liu, A. Karrech, S. Llana-Fúnez, X. Xiao, and K. Regenauer-Lieb We conducted an in-situ X-ray micro-computed tomography heating experiment at the Advanced Photon Source (USA) to dehydrate an unconfined 2.3 mm diameter cylinder of Volterra Gypsum. We used a purpose-built X-ray transparent furnace to heat the sample to 388 K for a total of 310 min to acquire a three-dimensional time-series tomography dataset comprising nine time steps. The voxel size of 2.2 μm 3 proved sufficient to pinpoint reaction initiation and the organization of drainage architecture in space and time. We observed that dehydration commences across a narrow front, which propagates from the margins to the centre of the sample in more than four hours. The advance of this front can be fitted with a square-root function, implying that the initiation of the reaction in the sample can be described as a diffusion process. Novel parallelized computer codes allow quantifying the geometry of the porosity and the drainage architecture from the very large tomographic datasets (2048 3 voxels) in unprecedented detail. We determined position, volume, shape and orientation of each resolvable pore and tracked these properties over the duration of the experiment. We found that the pore-size distribution follows a power law. Pores tend to be anisotropic but rarely crack-shaped and have a preferred orientation, likely controlled by a pre-existing fabric in the sample. With on-going dehydration, pores coalesce into a single interconnected pore cluster that is connected to the surface of the sample cylinder and provides an effective drainage pathway. Our observations can be summarized in a model in which gypsum is stabilized by thermal expansion stresses and locally increased pore fluid pressures until the dehydration front approaches to within about 100 μm. Then, the internal stresses are released and dehydration happens efficiently, resulting in new pore space. Pressure release, the production of pores and the advance of the front are coupled in a feedback loop.

Beschreibung: Coupling of climate models and ice sheet models by surface mass balance gradients: application to the Greenland Ice Sheet The Cryosphere, 6, 255-272, 2012 Author(s): M. M. Helsen, R. S. W. van de Wal, M. R. van den Broeke, W. J. van de Berg, and J. Oerlemans It is notoriously difficult to couple surface mass balance (SMB) results from climate models to the changing geometry of an ice sheet model. This problem is traditionally avoided by using only accumulation from a climate model, and parameterizing the meltwater run-off as a function of temperature, which is often related to surface elevation ( H s ). In this study, we propose a new strategy to calculate SMB, to allow a direct adjustment of SMB to a change in ice sheet topography and/or a change in climate forcing. This method is based on elevational gradients in the SMB field as computed by a regional climate model. Separate linear relations are derived for ablation and accumulation, using pairs of H s and SMB within a minimum search radius. The continuously adjusting SMB forcing is consistent with climate model forcing fields, also for initially non-glaciated areas in the peripheral areas of an ice sheet. When applied to an asynchronous coupled ice sheet – climate model setup, this method circumvents traditional temperature lapse rate assumptions. Here we apply it to the Greenland Ice Sheet (GrIS). Experiments using both steady-state forcing and glacial-interglacial forcing result in realistic ice sheet reconstructions.

Beschreibung: Estimating ice phenology on large northern lakes from AMSR-E: algorithm development and application to Great Bear Lake and Great Slave Lake, Canada The Cryosphere, 6, 235-254, 2012 Author(s): K.-K. Kang, C. R. Duguay, and S. E. L. Howell Time series of brightness temperatures ( T B ) from the Advanced Microwave Scanning Radiometer–Earth Observing System (AMSR-E) are examined to determine ice phenology variables on the two largest lakes of northern Canada: Great Bear Lake (GBL) and Great Slave Lake (GSL). T B measurements from the 18.7, 23.8, 36.5, and 89.0 GHz channels (H- and V- polarization) are compared to assess their potential for detecting freeze-onset/melt-onset and ice-on/ice-off dates on both lakes. The 18.7 GHz (H-pol) channel is found to be the most suitable for estimating these ice dates as well as the duration of the ice cover and ice-free seasons. A new algorithm is proposed using this channel and applied to map all ice phenology variables on GBL and GSL over seven ice seasons (2002–2009). Analysis of the spatio-temporal patterns of each variable at the pixel level reveals that: (1) both freeze-onset and ice-on dates occur on average about one week earlier on GBL than on GSL (Day of Year (DY) 318 and 333 for GBL; DY 328 and 343 for GSL); (2) the freeze-up process or freeze duration (freeze-onset to ice-on) takes a slightly longer amount of time on GBL than on GSL (about 1 week on average); (3) melt-onset and ice-off dates occur on average one week and approximately four weeks later, respectively, on GBL (DY 143 and 183 for GBL; DY 135 and 157 for GSL); (4) the break-up process or melt duration (melt-onset to ice-off) lasts on average about three weeks longer on GBL; and (5) ice cover duration estimated from each individual pixel is on average about three weeks longer on GBL compared to its more southern counterpart, GSL. A comparison of dates for several ice phenology variables derived from other satellite remote sensing products (e.g. NOAA Interactive Multisensor Snow and Ice Mapping System (IMS), QuikSCAT, and Canadian Ice Service Database) show that, despite its relatively coarse spatial resolution, AMSR-E 18.7 GHz provides a viable means for monitoring of ice phenology on large northern lakes.

Beschreibung: Hong-xiang Sun, Shu-yi Zhang, and Xiu-ji Shui A model of acoustic diodes is realized by a thin brass plate with single-sided periodical grating structure immersed in water and studied both numerically and experimentally. The unidirectional transmission of acoustic waves is identified in two different frequency ranges, which can be systematicall ... [Appl. Phys. Lett. 100, 103507 (2012)] published Fri Mar 9, 2012.

Beschreibung: Xiaolei Wang, Kai Han, Wenwu Wang, Hong Yang, Jing Zhang et al. Band alignment of TiN/HfO interface of TiN/HfO/SiO/Si stack is investigated by x-ray photoelectron spectroscopy (XPS). The p-type Schottky barrier height (p-SBH) is found to increase with thicker HfO thickness. Since considering only the metal/dielectric interface cannot explain this phenomenon, ban ... [Appl. Phys. Lett. 100, 102906 (2012)] published Fri Mar 9, 2012.

Beschreibung: Wei Zou, Zhizhou Yu, C. X. Zhang, J. X. Zhong, and L. Z. Sun The transport properties of hybrid nanoribbons constructed by substituting zigzag graphane nanoribbons into zigzag graphene nanoribbons are investigated using the first-principles calculations and non-equilibrium Green's function. The transport properties of the hybrid systems are improved due to th ... [Appl. Phys. Lett. 100, 103109 (2012)] published Fri Mar 9, 2012.

Beschreibung: Brian E. Francisco, Christina M. Jones, Se-Hee Lee, and Conrad R. Stoldt While today's lithium-ion batteries offer acceptable energy storage capability, they lack the ability to be cycled repeatedly more than a couple thousand times. Electrochemical capacitors, i.e., supercapacitors, are being developed whose lifetimes exceed 1 x 10 cycles and power densities surpass t ... [Appl. Phys. Lett. 100, 103902 (2012)] published Fri Mar 9, 2012.

Beschreibung: Chun Cheng, Kai Liu, Bin Xiang, Joonki Suh, and Junqiao Wu Recently, it was discovered that single-crystalline VO nanostructures exhibit unique, single-domain metal-insulator phase transition. They enable a wide range of device applications as well as discoveries of oxide physics beyond those can be achieved with VO bulk or thin films. Previous syntheses of ... [Appl. Phys. Lett. 100, 103111 (2012)] published Fri Mar 9, 2012.

Beschreibung: Jing-Xin Yu, Yan Cheng, Stefano Sanvito, and Xiang-Rong Chen The bias-dependent oscillatory electron transport of monatomic sulfur chains sandwiched between gold electrodes is investigated with density functional theory and non-equilibrium Green's function method. At zero bias, in contrast to the typical odd-even oscillations observed in most metallic chains, ... [Appl. Phys. Lett. 100, 103110 (2012)] published Fri Mar 9, 2012.

Beschreibung: Jing Lou, Gerry N. Pellegrini, Ming Liu, Neil D. Mathur, and Nian X. Sun We demonstrate an equivalence between direct and converse magnetoelectric effects in two-phase systems comprising piezoelectric and magnetostrictive materials. This was achieved by recasting the Maxwell relation in terms of the effective electrical and magnetic dipole moments for the system and comp ... [Appl. Phys. Lett. 100, 102907 (2012)] published Fri Mar 9, 2012.

Beschreibung: Fei Ding, Yanxia Cui, Xiaochen Ge, Yi Jin, and Sailing He A microwave ultra-broadband polarization-independent metamaterial absorber is demonstrated. It is composed of a periodic array of metal-dielectric multilayered quadrangular frustum pyramids. These pyramids possess resonant absorption modes at multi-frequencies, of which the overlapping leads to the ... [Appl. Phys. Lett. 100, 103506 (2012)] published Fri Mar 9, 2012.

Beschreibung: Jie Su, Xiaomei Lu, Yaoyang Liu, Junting Zhang, Guorong Li et al. 0.7Pb(ZrTi)O-0.3Pb(NiNb)O (abbreviated as PZT-PNN) ceramics were prepared using the solid-state reaction method. The results reveal that ferroelectric and anti-ferromagnetic orderings coexist (multiferroicity) in PZT-PNN ceramics. Furthermore, the abnormal behavior of dielectric constant and loss ob ... [Appl. Phys. Lett. 100, 102905 (2012)] published Fri Mar 9, 2012.

Beschreibung: Yuan Tian, Hongliang Lu, Jifa Tian, Chen Li, Chao Hui et al. Magnesium-doped boron nanoswords were synthesized via a thermoreduction method. The as-prepared nanoswords are single crystalline and beta-rhombohedral (beta-rh) phase. Electrical transport measurements show that variable range hopping conductivity increases with temperature, and carrier mobility ha ... [Appl. Phys. Lett. 100, 103112 (2012)] published Fri Mar 9, 2012.

Beschreibung: Yohanna Seminovski, Pablo Palacios, Perla Wahnon, and Ricardo Grau-Crespo Based on theoretical arguments, we propose a possible route for controlling the band-gap in the promising photovoltaic material CdInS. Our ab initio calculations show that the experimental degree of inversion in this spinel (fraction of tetrahedral sites occupied by In) corresponds approximately to ... [Appl. Phys. Lett. 100, 102112 (2012)] published Fri Mar 9, 2012.

Beschreibung: Takao Shimizu, Desheng Fu, Hiroki Taniguchi, Tomoyasu Taniyama, and Mitsuru Itoh We perform a Raman scattering study to elucidate the mechanism of temperature independent dielectric response of BaCaTiO (BCTO-0.233) from a viewpoint of phonon dynamics. BCTO-0.233 remains tetragonal below T down to 3.5 K. Over-damped soft phonon observed in a pure BaTiO is found to become underdam ... [Appl. Phys. Lett. 100, 102908 (2012)] published Fri Mar 9, 2012.

Beschreibung: Levent Gutay, Alex Redinger, Rabie Djemour, and Susanne Siebentritt We present experimental proof for a narrow first conduction band in CuZnSnSe semiconductor films as it has been predicted by theoretical calculations. The optical absorption characteristics of CuZnSnSe thin films are analyzed by optical transmission spectroscopy. The experimental data show strong ev ... [Appl. Phys. Lett. 100, 102113 (2012)] published Fri Mar 9, 2012.

Beschreibung: Jibao Lu, Ying Dai, Meng Guo, Lin Yu, Kangrong Lai et al. The conflict of understandings on experimental results about chemical and optical properties of C-doped TiO, which has been overlooked for a long time but is essential for studies of the basic properties of this material, is unraveled. It is shown that in anatase TiO the doped C and O atoms can easi ... [Appl. Phys. Lett. 100, 102114 (2012)] published Fri Mar 9, 2012.

Beschreibung: Zhifeng Shi, Xiaochuan Xia, Wei Yin, Shikai Zhang, Hui Wang et al. Ultraviolet electroluminescence was demonstrated from a p-ZnO:As/n-SiC(6H) heterojunction light-emitting diode at room-temperature. The p-ZnO:As was fabricated by out-diffusion of arsenic atoms from a sandwiched GaAs interlayer on SiC substrate. The p-type doping was confirmed by both Hall and low-t ... [Appl. Phys. Lett. 100, 101112 (2012)] published Fri Mar 9, 2012.

Beschreibung: Saifeng Zhang, Wei Xie, Hongxing Dong, Liaoxin Sun, Yanjing Ling et al. A robust exciton-polariton effect in a ZnO whispering gallery microcavity well above room temperature is presented. The lower polariton branches are tuned by current induced thermal effect. The red shift can be as large as ~40 meV. It is found that the strong coupling can be preserved and the polari ... [Appl. Phys. Lett. 100, 101912 (2012)] published Fri Mar 9, 2012.

Beschreibung: J. A. Caraveo-Frescas, M. N. Hedhili, H. Wang, U. Schwingenschlogl, and H. N. Alshareef It is shown that the well-known negative flatband voltage (V) shift, induced by rare-earth oxide capping in metal gate stacks, can be completely reversed in the absence of the silicon overlayer. Using TaN metal gates and GdO-doped dielectric, we measure a ~350 mV negative shift with the Si overlayer ... [Appl. Phys. Lett. 100, 102111 (2012)] published Fri Mar 9, 2012.

Beschreibung: X. Y. Zhong, B. Kabius, D. K. Schreiber, J. A. Eastman, D. D. Fong et al. The protocol to calculate the chemical roughness from three-dimensional (3-D) data cube acquired by energy-filtered electron tomography has been developed and applied to analyze the 3-D Zr distribution at the arbitrarily shaped interfaces in the ZrO/InO multilayer films. The calculated root-mean-squ ... [Appl. Phys. Lett. 100, 101604 (2012)] published Fri Mar 9, 2012.

Beschreibung: Chunlei Wan, Yifeng Wang, Wataru Norimatsu, Michiko Kusunoki, and Kunihito Koumoto Layered metal sulfides (MS)(TiS) (M = Pb, Sn, Bi) with alternative stacking of MS layers and TiS layers (a natural superlattice) have been proposed as thermoelectric materials. In this paper, various nanoscale stacking faults have been found in these materials, including the translational disorder i ... [Appl. Phys. Lett. 100, 101913 (2012)] published Fri Mar 9, 2012.

Beschreibung: On the representation of immersion and condensation freezing in cloud models using different nucleation schemes Atmospheric Chemistry and Physics Discussions, 12, 7167-7209, 2012 Author(s): B. Ervens and G. Feingold Ice nucleation in clouds is often observed at temperatures 〉235 K, pointing to heterogeneous freezing as a predominant mechanism. Many models deterministically predict the number concentration of ice particles as a function of temperature and/or supersaturation. Laboratory experiments at constant temperature and/or supersaturation often report heterogeneous freezing as a stochastic, time-dependent process that follows classical nucleation theory which might appear to contradict singular freezing behavior. We explore the extent to which the choice of nucleation scheme (deterministic/stochastic, single/multiple contact angles θ) affects the prediction of the frozen ice nuclei (IN) fraction and cloud evolution. A box model with constant temperature and supersaturation is used to mimic published laboratory experiments of immersion freezing of kaolinite (~243 K), and the fitness of different nucleation schemes. Sensitivity studies show that agreement of all five schemes is restricted to the narrow parameter range (time, temperature, IN diameter) in the original laboratory studies. The schemes are implemented in an adiabatic parcel model that includes feedbacks of the formation and growth of drops and ice particles on supersaturation during the ascent of an air parcel. Model results show that feedbacks of droplets and ice on supersaturation limit ice nucleation events, often leading to smaller differences in number concentration of ice particles and ice water content (IWC) between stochastic and deterministic approaches than expected from the box model studies. However, the different parameterizations of θ distributions and time-dependencies are highly sensitive to IN size and can lead to great differences in predicted ice number concentrations and IWC between the different schemes. Finally, since the choice of nucleation scheme determines the temperature range over which nucleation occurs, at habit-prone temperatures (~253 K) different onset temperatures of freezing create variability in the initial inherent growth ratio of ice particles, which can lead to amplification or reduction in differences in predicted IWC.

Beschreibung: A sun-tracking method to improve the pointing accuracy of weather radar Atmospheric Measurement Techniques, 5, 547-555, 2012 Author(s): X. Muth, M. Schneebeli, and A. Berne Accurate positioning of data collected by a weather radar is of primary importance for their appropriate georeferencing, which in turn makes it possible to combine those with additional sources of information (topography, land cover maps, meteorological simulations from numerical weather models to list a few). This issue is especially acute for mobile radar systems, for which accurate and stable leveling might be difficult to ensure. The sun is a source of microwave radiation, which can be detected by weather radars and used for accurate positioning of radar data. This paper presents a technique based on the similarity between theodolites and radar systems as well as on the sun echoes to quantify and hence correct the instrumental errors which can affect the pointing accuracy of radar antenna. The proposed method is applied to data collected in the Swiss Alps using a mobile X-band radar system. The obtained instrumental bias values are evaluated by comparing the locations of the ground echoes predicted using these bias estimates with the observed ground echo locations. The very good agreement between the two confirms the accuracy of the proposed method.

Beschreibung: A multi-model assessment of the efficacy of sea spray geoengineering Atmospheric Chemistry and Physics Discussions, 12, 7125-7166, 2012 Author(s): K. J. Pringle, K. S. Carslaw, T. Fan, G.W. Mann, A. Hill, P. Stier, K. Zhang, and H. Tost Artificially increasing the albedo of marine clouds by the mechanical emission of sea spray aerosol has been proposed as a geoengineering technique to slow the warming caused by anthropogenic greenhouse gases. A previous global model study found that only modest increases and sometimes even decreases in cloud drop number (CDN) concentrations would result from plausible emission scenarios. Here we extend that work to examine the conditions under which decreases in CDN can occur, and use three independent global models to quantify maximum achievable CDN changes. We find that decreases in CDN can occur when at least three of the following conditions are met: the injected particle number is 250–300 nm, the background aerosol loading is large (≥150 cm −3 ) and the in-cloud updraught velocity is low (

Beschreibung: Effects of seawater p CO 2 changes on the calcifying fluid of scleractinian corals Biogeosciences Discussions, 9, 2655-2689, 2012 Author(s): S. Hohn and A. Merico Rising atmospheric CO 2 concentrations due to anthropogenic emissions induce changes in the ocean carbonate chemistry and a drop in ocean pH. This acidification process is expected to harm calcifying organisms like coccolithophores, molluscs, echinoderms, and corals. A severe decline in coral abundance is, for example, expected by the end of this century with associated disastrous effects on reef ecosystems. Despite the growing importance of the topic, little progress has been made with respect to modelling the impact of acidification on coral calcification. Here we present a model for a coral polyp that simulates the carbonate system in four different compartments: the seawater, the polyp tissue, the coelenteron, and the calicoblastic layer. Precipitation of calcium carbonate takes place in the metabolically controlled calicoblastic layer beneath the polyp tissue. The model is adjusted to a state of activity as observed by direct microsensor measurements in the calcifying fluid. Simulated CO 2 perturbation experiments reveal decreasing calcification rates under elevated p CO 2 despite strong metabolic control of the calcifying fluid. Diffusion of CO 2 through the tissue into the calicoblastic layer increases with increasing seawater p CO 2 leading to decreased aragonite saturation in the calcifying fluid of the coral polyp. Our modelling study provides important insights into the complexity of the calcification process at the organism level and helps to quantify the effect of ocean acidification on corals.

Beschreibung: The role of the seagrass Posidonia oceanica in the cycling of trace elements Biogeosciences Discussions, 9, 2623-2653, 2012 Author(s): C. Sanz-Lázaro, P. Malea, E. T. Apostolaki, I. Kalantzi, A. Marín, and I. Karakassis The aim of this work was to study the role of the seagrass Posidonia oceanica on the cycling of a wide set of trace elements (Ag, As, Ba, Bi, Cd, Co, Cr, Cs, Cu, Fe, Ga, Li, Mn, Ni, Pb, Rb, Sr, Tl, V and Zn). We measured the concentration of these trace elements in the different compartments of P. oceanica (leaves, rhizomes, roots and epibiota) in a non-polluted seagrass meadow representative of the Mediterranean and calculated the annual budget from a mass balance. We provide novel data on accumulation dynamics of many trace elements in P. oceanica compartments and demonstrate that trace element accumulation patterns are mainly determined by plant compartment rather than by temporal variability. Epibiota was the compartment which showed the greatest concentrations for most trace elements. Thus, they constitute a key compartment when estimating trace element transfer to higher trophic levels by P. oceanica . For most trace elements, translocation seemed to be low and acropetal. Zn, Cd, Sr and Rb were the trace elements that showed the highest release rate through decomposition of plant detritus, while Cs, Tl and Bi the lowest. P. oceanica acts as a sink of potentially toxic trace elements (Ni, Cr, As and Ag), which can be sequestered, decreasing their bioavailability. P. oceanica may have a relevant role in the cycling of trace elements in the Mediterranean.

Beschreibung: Smoke aerosol and its radiative effects during extreme fire event over Central Russia in summer 2010 Atmospheric Measurement Techniques, 5, 557-568, 2012 Author(s): N. Chubarova, Ye. Nezval', I. Sviridenkov, A. Smirnov, and I. Slutsker Different microphysical, optical and radiative properties of aerosol were analyzed during the severe fires in summer 2010 over Central Russia using ground measurements at two AERONET sites in Moscow (Meteorological Observatory of Moscow State University – MSU MO) and Zvenigorod (Moscow Region) and radiative measurements at the MSU MO. Volume aerosol size distribution in smoke conditions had a bimodal character with the significant prevalence of fine mode particles, for which effective radius was shifted to higher values ( r eff-fine = 0.24 μm against approximately 0.15 μm in typical conditions). For smoke aerosol, the imaginary part of refractive index (REFI) in the visible spectral region was lower than that for typical aerosol (REFI λ =675 nm = 0.006 against REFI λ =675 nm = 0.01), while single scattering albedo (SSA) was significantly higher (SSA λ =675 nm = 0.95 against SSA λ =675 nm ~ 0.9). Extremely high aerosol optical thickness at 500 nm (AOT500) was observed on 6–8 August reaching the absolute maximum on 7 August in Moscow (AOT500 = 6.4) and at Zvenigorod (AOT500 = 5.9). A dramatic attenuation of solar irradiance at ground was also recorded. Maximum irradiance loss had reached 64% for global shortwave irradiance, 91% for UV radiation 300–380 nm, and 97% for erythemally-weighted UV irradiance at relatively high solar elevation 47°. Significant spectral dependence in attenuation of solar irradiance in smoky conditions was mainly explained by higher AOT and smaller SSA in UV (0.8–0.9) compared with SSA in the visible region of spectrum. The assessments of radiative forcing effect (RFE) at the TOA indicated a significant cooling of the smoky atmosphere. Instant RFE reached −167 Wm −2 at AOT500 = 6.4, climatological RFE calculated with August 2010 monthly mean AOT was about −65 Wm −2 , compared with −20 Wm −2 for typical aerosol according to the 10 yr period of measurements in Moscow.

Beschreibung: Mohammad Farazmand and George Haller Using the recently developed variational theory of hyperbolic Lagrangian coherent structures (LCSs), we introduce a computational approach that renders attracting and repelling LCSs as smooth, parametrized curves in two-dimensional flows. The curves are obtained as trajectories of an autonomous ordi ... [Chaos 22, 013128 (2012)] published Fri Mar 9, 2012.

Beschreibung: Lucas Illing, Alison M. Saunders, and Daniel Hahs We address the issue of multi-parameter estimation from scalar outputs of chaotic systems, using the dynamics of a Malkus water wheel and simulations of the corresponding Lorenz-equations model as an example. We discuss and compare two estimators: one is based on a globally convergent adaptive obser ... [Chaos 22, 013127 (2012)] published Fri Mar 9, 2012.

Beschreibung: Fire history in western Patagonia from paired tree-ring fire-scar and charcoal records Climate of the Past, 8, 451-466, 2012 Author(s): A. Holz, S. Haberle, T. T. Veblen, R. De Pol-Holz, and J. Southon Fire history reconstructions are typically based on tree ages and tree-ring fire scars or on charcoal in sedimentary records from lakes or bogs, but rarely on both. In this study of fire history in western Patagonia (47–48° S) in southern South America (SSA) we compared three sedimentary charcoal records collected in bogs with tree-ring fire-scar data collected at 13 nearby sample sites. We examined the temporal and spatial correspondence between the two fire proxies and also compared them to published charcoal records from distant sites in SSA, and with published proxy reconstructions of regional climate variability and large-scale climate modes. Two of our three charcoal records record fire activity for the last 4 ka yr and one for the last 11 ka yr. For the last ca. 400 yr, charcoal accumulation peaks tend to coincide with high fire activity in the tree-ring fire scar records, but the charcoal records failed to detect some of the fire activity recorded by tree rings. Potentially, this discrepancy reflects low-severity fires that burn in herbaceous and other fine fuels without depositing charcoal in the sedimentary record. Periods of high fire activity tended to be synchronous across sample areas, across proxy types, and with proxy records of regional climatic variability as well as major climate drivers. Fire activity throughout the Holocene in western Patagonia has responded to regional climate variation affecting a broad region of southern South America that is teleconnected to both tropical- and high-latitude climate drivers-El Niño-Southern Oscillation and the Southern Annular Mode. An early Holocene peak in fire activity pre-dates any known human presence in our study area, and consequently implicates lightning as the ignition source. In contrast, the increased fire activity during the 20th century, which was concomitantly recorded by charcoal from all the sampled bogs and at all fire-scar sample sites, is attributed to human-set fires and is outside the range of variability characteristic of these ecosystems over many centuries and probably millennia.

Beschreibung: Exploring errors in paleoclimate proxy reconstructions using Monte Carlo simulations: paleotemperature from mollusk and coral geochemistry Climate of the Past, 8, 433-450, 2012 Author(s): M. Carré, J. P. Sachs, J. M. Wallace, and C. Favier Quantitative reconstructions of the past climate statistics from geochemical coral or mollusk records require quantified error bars in order to properly interpret the amplitude of the climate change and to perform meaningful comparisons with climate model outputs. We introduce here a more precise categorization of reconstruction errors, differentiating the error bar due to the proxy calibration uncertainty from the standard error due to sampling and variability in the proxy formation process. Then, we propose a numerical approach based on Monte Carlo simulations with surrogate proxy-derived climate records. These are produced by perturbing a known time series in a way that mimics the uncertainty sources in the proxy climate reconstruction. A freely available algorithm, MoCo, was designed to be parameterized by the user and to calculate realistic systematic and standard errors of the mean and the variance of the annual temperature, and of the mean and the variance of the temperature seasonality reconstructed from marine accretionary archive geochemistry. In this study, the algorithm is used for sensitivity experiments in a case study to characterize and quantitatively evaluate the sensitivity of systematic and standard errors to sampling size, stochastic uncertainty sources, archive-specific biological limitations, and climate non-stationarity. The results of the experiments yield an illustrative example of the range of variations of the standard error and the systematic error in the reconstruction of climate statistics in the Eastern Tropical Pacific. Thus, we show that the sample size and the climate variability are the main sources of the standard error. The experiments allowed the identification and estimation of systematic bias that would not otherwise be detected because of limited modern datasets. Our study demonstrates that numerical simulations based on Monte Carlo analyses are a simple and powerful approach to improve the understanding of the proxy records. We show that the standard error for the climate statistics linearly increases with the climate variability, which means that the accuracy of the error estimated by MoCo is limited by the climate non-stationarity.

Beschreibung: The relative roles of CO 2 and palaeogeography in determining Late Miocene climate: results from a terrestrial model-data comparison Climate of the Past Discussions, 8, 715-786, 2012 Author(s): C. D. Bradshaw, D. J. Lunt, R. Flecker, U. Salzmann, M. J. Pound, A. M. Haywood, and J. T. Eronen The Late Miocene (∼11.6–5.3 Ma) palaeorecord provides evidence for a warmer and wetter climate than that of today and there is uncertainty in the palaeo-CO 2 record of at least 150 ppmv. We present results from fully coupled atmosphere-ocean-vegetation simulations for the Late Miocene that examine the relative roles of palaeogeography (topography and ice sheet geometry) and CO 2 concentration in the determination of Late Miocene climate through comprehensive terrestrial model-data comparisons. Assuming that the data accurately reflects the Late Miocene climate, and that the Late Miocene palaeogeographic reconstruction used in the model is robust, then results indicate that the proxy-derived precipitation differences between the Late Miocene and modern can be largely accounted for by the palaeogeographic changes alone. However, the proxy-derived temperatures differences between the Late Miocene and modern can only begin to be accounted for if we assume a palaeo-CO 2 concentration towards the higher end of the range of estimates.

Beschreibung: Changes in the strength and width of the Hadley circulation since 1871 Climate of the Past Discussions, 8, 695-713, 2012 Author(s): J. Liu, M. Song, Y. Hu, and X. Ren Recent studies demonstrate that the Hadley Circulation has intensified and expanded for the past three decades, which has important implications for subtropical societies and may lead to profound changes in global climate. However, the robustness of this intensification and expansion that should be considered when interpreting long-term changes of the Hadley Circulation is still matters of debate. It also remains largely unknown how the Hadley Circulation has evolved over longer periods. Here we present long-term variability of the Hadley Circulation using the 20th Century Reanalysis. It shows a slight strengthening and widening of the Hadley Circulation since the late 1970s, which is not inconsistent with recent assessments. However, over centennial timescales (1871–2008), the Hadley Circulation shows a tendency towards more intense and narrower state. More importantly, the width of the Hadley Circulation has not yet completed a life-cycle since 1871. The strength and width of the Hadley Circulation during the late 19th and early 20th century show strong natural variability, exceeding variability that coincides with global warming in recent decades. These findings raise the question that the recent change of the Hadley Circulation is primarily attributed to greenhouse warming or a long-period oscillation of the Hadley Circulation substantially longer than that observed in previous studies.

Beschreibung: A. A. Gonzalez-Fernandez, J. Juvert, Alfredo Morales-Sanchez, Jorge Barreto, M. Aceves-Mijares et al. This work presents electrical and electro-optical studies performed on light-emitting capacitors with silicon-rich silicon oxide fabricated by plasma-enhanced chemical vapor deposition and by the implantation of Si ions in thermally grown SiO. The influence of the fabrication technique and silicon c ... [J. Appl. Phys. 111, 053109 (2012)] published Thu Mar 8, 2012.

Beschreibung: Alvaro Valdes, Rita Prosmiti, and Gerardo Delgado-Barrio A full-dimensional quantum dynamics study is carried out for the highly fluxional H cation on a recent reference potential energy surface by using the multi configuration time-dependent Hartree method. With five equivalent light atoms and shallow barriers between various low-lying stationary points ... [J. Chem. Phys. 136, 104302 (2012)] published Thu Mar 8, 2012.

Beschreibung: Towards a regional ocean forecasting system for the IBI (Iberia-Biscay-Ireland area): developments and improvements within the ECOOP project framework Ocean Science, 8, 143-159, 2012 Author(s): S. Cailleau, J. Chanut, J.-M. Lellouche, B. Levier, C. Maraldi, G. Reffray, and M. G. Sotillo The regional ocean operational system remains a key element in downscaling from large scale (global or basin scale) systems to coastal ones. It enables the transition between systems in which the resolution and the resolved physics are quite different. Indeed, coastal applications need a system to predict local high frequency events (inferior to the day) such as storm surges, while deep sea applications need a system to predict large scale lower frequency ocean features. In the framework of the ECOOP project, a regional system for the Iberia-Biscay-Ireland area has been upgraded from an existing V0 version to a V2. This paper focuses on the improvements from the V1 system, for which the physics are close to a large scale basin system, to the V2 for which the physics are more adapted to shelf and coastal issues. Strong developments such as higher regional physics resolution in the NEMO Ocean General Circulation Model for tides, non linear free surface and adapted vertical mixing schemes among others have been implemented in the V2 version. Thus, regional thermal fronts due to tidal mixing now appear in the latest version solution and are quite well positioned. Moreover, simulation of the stratification in shelf areas is also improved in the V2.

Beschreibung: M. H. Stockett and J. E. Lawler A novel absorption cell has been developed to enable a spectroscopic survey of a broad range of polycyclic aromatic hydrocarbons (PAH) under astrophysically relevant conditions and utilizing a synchrotron radiation continuum to test the still controversial hypothesis that these molecules or their io ... [Rev. Sci. Instrum. 83, 035104 (2012)] published Fri Mar 9, 2012.

Beschreibung: Arctic sea ice variability and trends, 1979–2010 The Cryosphere Discussions, 6, 957-979, 2012 Author(s): D. J. Cavalieri and C. L. Parkinson Analyses of 32 yr (1979–2010) of Arctic sea ice extents and areas derived from satellite passive microwave radiometers are presented for the Northern Hemisphere as a whole and for nine Arctic regions. There is an overall negative yearly trend of −51.5 ± 4.1 × 10 3 km 2 yr −1 (−4.1 ± 0.3% decade −1 ) in sea ice extent for the hemisphere. The sea ice extent trends for the individual Arctic regions are all negative except for the Bering Sea: −3.9 ± 1.1 × 10 3 km 2 yr −1 (−8.7 ± 2.5% decade −1 ) for the Seas of Okhotsk and Japan, +0.3 ± 0.8 × 10 3 km 2 yr −1 (+1.2 ± 2.7% decade −1 ) for the Bering Sea, −4.4 ± 0.7 × 10 3 km 2 yr −1 (−5.1 ± 0.9% decade −1 ) for Hudson Bay, −7.6 ± 1.6 × 10 3 km 2 yr −1 (−8.5 ± 1.8% decade −1 ) for Baffin Bay/Labrador Sea, −0.5 ± 0.3 × 10 3 km 2 yr −1 (−5.9 ± 3.5% decade −1 ) for the Gulf of St. Lawrence, −6.5 ± 1.1 × 10 3 km 2 yr −1 (−8.6 ± 1.5% decade −1 ) for the Greenland Sea, −13.5 ± 2.3 × 10 3 km 2 yr −1 (−9.2 ± 1.6% decade −1 ) for the Kara and Barents Seas, −14.6 ± 2.3 × 10 3 km 2 yr −1 (−2.1 ± 0.3% decade −1 ) for the Arctic Ocean, and −0.9 ± 0.4 × 10 3 km 2 yr −1 (−1.3 ± 0.5% decade −1 ) for the Canadian Archipelago. Similarly, the yearly trends for sea ice areas are all negative except for the Bering Sea. On a seasonal basis for both sea ice extents and areas, the largest negative trend is observed for summer with the next largest negative trend being for autumn.

Beschreibung: N. Tezuka, F. Mitsuhashi, and S. Sugimoto Tunnel magnetoresistance effect has been investigated for magnetic tunnel junctions with CoFeAlSi Heusler electrodes on a Cr-bufferd MgO (110) substrate. The grown CoFeAlSi has L2 structure for annealing above 500 degrees C. The TMR ratio of 73% at room temperature and 103% at 5 K were obtained for ... [J. Appl. Phys. 111, 07C718 (2012)] published Fri Mar 9, 2012.

Beschreibung: Manh Cuong Nguyen, Xin Zhao, Min Ji, Cai-Zhuang Wang, Bruce Harmon et al. Using genetic algorithm with first-principle calculations, we searched for low-energy crystal structures of FeCo alloys. We found that FeCo alloys are highly configurationally degenerate with many additional off-stoichiometric stable structures to the well-known B structure. The average magnetic mom ... [J. Appl. Phys. 111, 07E338 (2012)] published Fri Mar 9, 2012.

Beschreibung: Kazuhiko Okita, Kazushi Ishiyama, and Hideo Miura Magnetostriction constant of a magnetic thin film is conventionally measured by detecting the deformation of a coupon sample that consists of the magnetic film deposited on a thin glass substrate (e.g., cover glass of size 10 mm x 25 mm) under an applied field using a laser beam [A. C. Tam and H. ... [J. Appl. Phys. 111, 07E340 (2012)] published Fri Mar 9, 2012.

Beschreibung: Yuan-Feng Duan, Chung Ming Leung, Shengyao Zhang, Long Zhang, and Siu Wing Or A polymer-based magnetoelectric (ME) laminate was fabricated by sandwiching one layer of thickness-polarized, length-stretched polyvinylidene fluoride (PVDF) piezoelectric polymer between two layers of length-magnetized, epoxy-bonded TbDyFe (Terfenol-D) pseudo-13 magnetostrictive particulate composi ... [J. Appl. Phys. 111, 07C717 (2012)] published Fri Mar 9, 2012.

Beschreibung: On teaching styles of water educators and the impact of didactic training Hydrology and Earth System Sciences Discussions, 9, 2959-2986, 2012 Author(s): A. Pathirana, J. H. Koster, E. de Jong, and S. Uhlenbrook Solving today's complex hydrological problems requires originality, creative thinking and trans-disciplinary approaches. Hydrological education that was traditionally teacher centred, where the students look up to the teacher for expertise and information, should change to better prepare hydrologists to develop new knowledge and apply it in new contexts. An important first step towards this goal is to change the concept of education in the educators' minds. The results of an investigation to find out whether didactic training influences the beliefs of hydrology educators about their teaching styles is presented. Faculty of UNESCO-IHE has been offered a didactic certification program named University Teaching Qualification (UTQ). The hypothesis that UTQ training will significantly alter the teaching style of faculty at UNESCO-IHE from expert/formal authority traits towards facilitator/delegator traits was tested. A first survey was conducted among the entire teaching staff (total 101, response rate 58%). The results indicated that there are significantly higher traits of facilitator and delegator teaching styles among UTQ graduates compared to faculty who were not significantly trained in didactics. The second survey which was conducted among UTQ graduates (total 20, response rate 70%), enquiring after their teaching styles before and after UTQ, corroborated these findings.

Beschreibung: Characterization of deep aquifer dynamics using principal component analysis of sequential multilevel data Hydrology and Earth System Sciences, 16, 761-771, 2012 Author(s): D. Kurtzman, L. Netzer, N. Weisbrod, A. Nasser, E. R. Graber, and D. Ronen Two sequential multilevel profiles were obtained in an observation well opened to a 130-m thick, unconfined, contaminated aquifer in Tel Aviv, Israel. While the general profile characteristics of major ions, trace elements, and volatile organic compounds were maintained in the two sampling campaigns conducted 295 days apart, the vertical locations of high concentration gradients were shifted between the two profiles. Principal component analysis (PCA) of the chemical variables resulted in a first principal component which was responsible for ∼60% of the variability, and was highly correlated with depth. PCA revealed three distinct depth-dependent water bodies in both multilevel profiles, which were found to have shifted vertically between the sampling events. This shift cut across a clayey bed which separated the top and intermediate water bodies in the first profile, and was located entirely within the intermediate water body in the second profile. Continuous electrical conductivity monitoring in a packed-off section of the observation well revealed an event in which a distinct water body flowed through the monitored section ( v ∼ 150 m yr −1 ). It was concluded that the observed changes in the profiles result from dominantly lateral flow of water bodies in the aquifer rather than vertical flow. The significance of this study is twofold: (a) it demonstrates the utility of sequential multilevel observations from deep wells and the efficacy of PCA for evaluating the data; (b) the fact that distinct water bodies of 10 to 100 m vertical and horizontal dimensions flow under contaminated sites, which has implications for monitoring and remediation.

Beschreibung: Brooke L. Mesler, Kristen S. Buchanan, Mi-Young Im, and Peter Fischer We report experimental evidence of nonlinear gyrotropic vortex core motion. Using soft x-ray transmission microscopy we observed the time-averaged dynamic response of a magnetic vortex core in a 2 [mu]m diameter, 100 nm thick permalloy (NiFe) disk as a function of the amplitude and frequency of an a ... [J. Appl. Phys. 111, 07D311 (2012)] published Fri Mar 9, 2012.

Beschreibung: Sunjae Chung, Sangyeop Lee, Hakjoon Lee, Taehee Yoo, Sanghoon Lee et al. Two ferromagnetic semiconductor GaMnAs-based superlattices (SLs) were investigated by measuring the planar Hall effect (PHE) with the external magnetic field applied in the plane of the sample. The two GaMnAs/GaAs SLs differed only by the Be doping of the nonmagnetic GaAs spacer layers. Both SLs sho ... [J. Appl. Phys. 111, 07D310 (2012)] published Fri Mar 9, 2012.

Beschreibung: G. Consolo and E. Martinez In this paper a numerical investigation of the effects of disorder on the domain wall propagation along magnetic nanostrips induced by fields or currents is carried out. Such effects are included in the extended Landau-Lifshitz-Gilbert equation of motion by generalizing the classical viscous-type di ... [J. Appl. Phys. 111, 07D312 (2012)] published Fri Mar 9, 2012.

Beschreibung: Khabat Ebnabbasi, Yajie Chen, Anton Geiler, Vincent Harris, and Carmine Vittoria In this paper, magnetoelectric effects of Sr Z-type hexaferrite, SrFeCoO, at room temperature is measured. The change in remanence magnetization was measured by applying a DC voltage or electric field across a slab of hexaferrite. Changes of ~18% in remanence was observed in an electric field of 10 ... [J. Appl. Phys. 111, 07C719 (2012)] published Fri Mar 9, 2012.

Beschreibung: S. Narendra Babu, Seong-Gi Min, Amin Yourdkhani, Gabriel Caruntu, and Leszek Malkinski The present work is aimed at fabricating bi-layer aluminum nitride (AlN)/cobalt iron (CoFe) magnetoelectric (ME) thin films using reactive rf/dc magnetron sputtering. A systematic study on structural, morphological, piezoelectric, magnetic and magnetoelectric properties is undertaken. Except for AlN ... [J. Appl. Phys. 111, 07C720 (2012)] published Fri Mar 9, 2012.

Beschreibung: Tomoaki Inokuchi, Mizue Ishikawa, Hideyuki Sugiyama, Yoshiaki Saito, and Nobuki Tezuka Spin injection and detection properties in CoFe/AlO/SOI (Si on insulator) junctions were investigated by using Hanle effect measurements up to room temperature. Cross-sectional transmission electron microscope images and Fourier transform images of the CoFe/AlO/SOI junction, fabricated by using appr ... [J. Appl. Phys. 111, 07C316 (2012)] published Fri Mar 9, 2012.

Beschreibung: Hiroyuki Ohtori and Hiroshi Imamura This paper theoretically analyzes the Andreev reflection in normal-conductor/multi-band super-conductor junctions. We applied Bogoliubov-de Gennes equations to the case of superconductors with extended s-waves and calculated the respective point-contact Andreev reflection (PCAR) spectra. Our results ... [J. Appl. Phys. 111, 07C518 (2012)] published Fri Mar 9, 2012.

Beschreibung: W. M. Li, X. L. Huang, J. Z. Shi, Y. J. Chen, T. L. Huang et al. The motivation for this work is rooted in the reversal process that occurs in perpendicularly magnetic Co/Pd multilayered based bit-patterned media. In our work, temperature effect and angle dependence of critical fields (H) and switching field distribution (SFD) are studied by both experiment and s ... [J. Appl. Phys. 111, 07B917 (2012)] published Fri Mar 9, 2012.

Beschreibung: Youn Ho Park, Hyun Cheol Jang, Hyun Cheol Koo, Hyung-jun Kim, Joonyeon Chang et al. From the Shubnikov-de Haas oscillation, estimation of the spin[horizontal bar]orbit interaction parameter is possible only for very low temperature. An alternative method available for much wider temperature range is utilizing the ferromagnetic electrode which contacts the quantum well channel and r ... [J. Appl. Phys. 111, 07C317 (2012)] published Fri Mar 9, 2012.

Beschreibung: S. N. Piramanayagam, M. Ranjbar, H. K. Tan, W. C. Allen Poh, R. Sbiaa et al. Antidots of Co/Pd multilayers with 3-bilayers [(Co/Pd)] that were antiferromagnetically coupled(AFC) to (Co/Pd) were fabricated and their magnetic properties were investigated. The thickness of Co in (Co/Pd) was varied from 0.4 to 0.8 nm. Samples with a Co thickness of 0.8 nm in the bilayer showed a ... [J. Appl. Phys. 111, 07B916 (2012)] published Fri Mar 9, 2012.

Beschreibung: Seyong Choi, Jang-Hee Yoon, Byoung-Seob Lee, Mi-Sook Won, Jung-Woo Ok et al. We investigate the performance of a magnetic lens in very high magnetic fields exceeding 24 T. The magnetic lens is composed of Gd-Ba-Cu-O superconducting bulk materials. The unique configuration of the magnetic field amplifier, which consists of slits and electrical insulation in the bulk, allows t ... [J. Appl. Phys. 111, 07E728 (2012)] published Fri Mar 9, 2012.

Beschreibung: Identifying the causes of differences in ozone production from the CB05 and CBMIV chemical mechanisms Geoscientific Model Development, 5, 257-268, 2012 Author(s): R. D. Saylor and A. F. Stein An investigation was conducted to identify the mechanistic differences between two versions of the carbon bond gas-phase chemical mechanism (CB05 and CBMIV) which consistently lead to larger ground-level ozone concentrations being produced in the CB05 version of the National Air Quality Forecasting Capability (NAQFC) modeling system even though the two parallel forecast systems utilize the same meteorology and base emissions and similar initial and boundary conditions. Box models of each of the mechanisms as they are implemented in the NAQFC were created and a set of 12 sensitivity simulations was designed. The sensitivity simulations independently probed the conceptual mechanistic differences between CB05 and CBMIV and were exercised over a 45-scenario simulation suite designed to emulate the wide range of chemical regimes encountered in a continental-scale atmospheric chemistry model. Results of the sensitivity simulations indicate that two sets of reactions that were included in the CB05 mechanism, but which were absent from the CBMIV mechanism, are the primary causes of the greater ozone production in the CB05 version of the NAQFC. One set of reactions recycles the higher organic peroxide species of CB05 (ROOH), resulting in additional photochemically reactive products that act to produce additional ozone in some chemical regimes. The other set of reactions recycles reactive nitrogen from less reactive forms back to NO 2 , increasing the effective NO x concentration of the system. In particular, the organic nitrate species (NTR), which was a terminal product for reactive nitrogen in the CBMIV mechanism, acts as a reservoir species in CB05 to redistribute NO x from major source areas to potentially NO x -sensitive areas where additional ozone may be produced in areas remote from direct NO x sources.

Beschreibung: The Nexus Land-Use model version 1.0, an approach articulating biophysical potentials and economic dynamics to model competition for land-use Geoscientific Model Development Discussions, 5, 571-638, 2012 Author(s): F. Souty, T. Brunelle, P. Dumas, B. Dorin, P. Ciais, R. Crassous, C. Müller, and A. Bondeau Interactions between food demand, biomass energy and forest preservation are driving both food prices and land-use changes, regionally and globally. This study presents a new model called Nexus Land-Use version 1.0 which describes these interactions through a generic representation of agricultural intensification mechanisms. The Nexus Land-Use model equations combine biophysics and economics into a single coherent framework to calculate crop yields, food prices, and resulting pasture and cropland areas within 12 regions inter-connected with each other by international trade. The representation of cropland and livestock production systems in each region relies on three components: (i) a biomass production function derived from the crop yield response function to inputs such as industrial fertilisers; (ii) a detailed representation of the livestock production system subdivided into an intensive and an extensive component, and (iii) a spatially explicit distribution of potential (maximal) crop yields prescribed from the Lund-Postdam-Jena global vegetation model for managed Land (LPJmL). The economic principles governing decisions about land-use and intensification are adapted from the Ricardian rent theory, assuming cost minimisation for farmers. The land-use modelling approach described in this paper entails several advantages. Firstly, it makes it possible to explore interactions among different types of biomass demand for food and animal feed, in a consistent approach, including indirect effects on land-use change resulting from international trade. Secondly, yield variations induced by the possible expansion of croplands on less suitable marginal lands are modelled by using regional land area distributions of potential yields, and a calculated boundary between intensive and extensive production. The model equations and parameter values are first described in details. Then, idealised scenarios exploring the impact of forest preservation policies or rising energy price on agricultural intensification are described, and their impacts on pasture and cropland areas are investigated.

Beschreibung: Editorial “Advances in Earth observation for water cycle science” Hydrology and Earth System Sciences, 16, 543-549, 2012 Author(s): D. Fernández-Prieto, P. van Oevelen, Z. Su, and W. Wagner

Beschreibung: Spiral structures and regularities in magnetic field variations and auroras History of Geo- and Space Sciences, 3, 1-31, 2012 Author(s): Y. I. Feldstein, L. I. Gromova, M. Förster, and A. E. Levitin The conception of spiral shaped precipitation regions, where solar corpuscles penetrate the upper atmosphere, was introduced into geophysics by C. Störmer and K. Birkeland at the beginning of the last century. Later, in the course of the XX-th century, spiral distributions were disclosed and studied in various geophysical phenomena. Most attention was devoted to spiral shapes in the analysis of regularities pertaining to the geomagnetic activity and auroras. We review the historical succession of perceptions about the number and positions of spiral shapes, that characterize the spatial-temporal distribution of magnetic disturbances. We describe the processes in the upper atmosphere, which are responsible for the appearance of spiral patterns. We considered the zones of maximal aurora frequency and of maximal particle precipitation intensity, as offered in the literature, in their connection with the spirals. We discuss the current system model, that is closely related to the spirals and that appears to be the source for geomagnetic field variations during magnetospheric substorms and storms. The currents in ionosphere and magnetosphere constitute together with field-aligned (along the geomagnetic field lines) currents (FACs) a common 3-D current system. At ionospheric heights, the westward and eastward electrojets represent characteristic elements of the current system. The westward electrojet covers the longitudinal range from the morning to the evening hours, while the eastward electrojet ranges from afternoon to near-midnight hours. The polar electrojet is positioned in the dayside sector at cusp latitudes. All these electrojets map along the magnetic field lines to certain plasma structures in the near-Earth space. The first spiral distribution of auroras was found based on observations in Antarctica for the nighttime-evening sector (N-spiral), and later in the nighttime-evening (N-spiral) and morning (M-spiral) sectors both in the Northern and Southern Hemispheres. The N- and M-spirals drawn in polar coordinates form an oval, along which one observes most often auroras in the zenith together with a westward electrojet. The nature of spiral distributions in geomagnetic field variations was unabmibuously interpreted after the discovery of the spiral's existence in the auroras had been established and this caused a change from the paradigm of the auroral zone to the paradigm of the auroral oval. Zenith forms of auroras are found within the boundaries of the auroral oval. The oval is therefore the region of most frequent precipitations of corpuscular fluxes with auroral energy, where anomalous geophysical phenomena occur most often and with maximum intensity. S. Chapman and L. Harang identified the existence of a discontinuity at auroral zone latitudes (Φ ∼ 67°) around midnight between the westward and eastward electrojets, that is now known as the Harang discontinuity. After the discovery of the auroral oval and the position of the westward electrojet along the oval, it turned out, that there is no discontinuity at a fixed latitude between the opposite electrojets, but rather a gap, the latitude of which varies smoothly between Φ ∼ 67° at midnight and Φ ∼ 73° at 20:00 MLT. In this respect the term ''Harang discontinuity'' represents no intrinsic phenomenon, because the westward electrojet does not experience any disruption in the midnight sector but continues without breaks from dawn to dusk hours.

Beschreibung: M. Godoy, A. J. Moreno, G. A. Jorge, H. J. Ferrari, P. S. Antonel et al. We report micrometric periodic assembly of live and dead magnetotactic bacteria, Magnetospirillum magneticum AMB-1, which synthesize chains of magnetic nanoparticles inside their bodies, and of superparamagnetic FeO and ferromagnetic CoFeO nanoparticles in aqueous suspensions using periodically magn ... [J. Appl. Phys. 111, 044905 (2012)] published Thu Feb 23, 2012.

Beschreibung: Mukannan Arivanandhan, Raira Gotoh, Tatsuro Watahiki, Kozo Fujiwara, Yasuhiro Hayakawa et al. The effect of Ge codoping on minority carrier lifetime in boron (B)-doped Czochralski-silicon (CZ-Si) crystals was investigated. The minority carrier lifetime increased from 110 to 176 [mu]s as Ge concentration was increased from zero to 1 x 10cm in B/Ge codoped CZ-Si crystals. Light-induced degra ... [J. Appl. Phys. 111, 043707 (2012)] published Thu Feb 23, 2012.

Beschreibung: S. S. Yakushkin, A. A. Dubrovskiy, D. A. Balaev, K. A. Shaykhutdinov, G. A. Bukhtiyarova et al. Magnetic properties of [eh]-FeO nanoparticles supported on silica with the average size of few nanometers, narrow size distribution and no admixture of any other iron oxide polymorphs are investigated. The investigation of the temperature behavior of magnetization within the temperature range from 4 ... [J. Appl. Phys. 111, 044312 (2012)] published Thu Feb 23, 2012.

Beschreibung: Biswadeep Saha, Meenakshisundaram Ramanathan, Chai Ren, and Sivaraman Guruswamy Dislocation arrays were introduced through controlled deformation of Fe20 at. % Ga alloy single crystal samples with and orientations. Alloy single crystals were obtained through vertical Bridgman growth process. Magnetostriction measurements show a large decrease in magnetostriction after deformi ... [J. Appl. Phys. 111, 043911 (2012)] published Thu Feb 23, 2012.

Beschreibung: Mudar A. Abdulsattar Infrared and Raman vibrational spectrum are calculated using ab initio density functional theory for SiGe superlattice nanocrystal of approximately 1.6 nm length. After obtaining the optimum positions of atoms via geometrical optimization using density functional theory, coupled perturbed Hartree-Fo ... [J. Appl. Phys. 111, 044306 (2012)] published Tue Feb 21, 2012.

Beschreibung: J. C. Lin, B. S. Wang, S. Lin, P. Tong, W. J. Lu et al. With increasing the substitution of Sn for Cu in CuSnMnNMn, the initial cubic-tetragonal structural phase transition disappears for the samples x 〉= 0.10 and is replaced by a discontinuous lattice expansion with a cubic structure which has been confirmed by the measurements of variable temperature x ... [J. Appl. Phys. 111, 043905 (2012)] published Tue Feb 21, 2012.

Beschreibung: Narihito Okada, Yoichi Yamada, and Kazuyuki Tadatomo Templates consisting of in-plane alternately arranged relaxed InGaN and GaN were obtained by (1122) facet growth and mass transport via metal-organic vapor phase epitaxy. InGaN/GaN multi-quantum wells (MQWs) were grown on the novel templates, and their optical and structural properties were investig ... [J. Appl. Phys. 111, 043508 (2012)] published Tue Feb 21, 2012.