bluuebunny/crossref_metadata_2025 huggingface dataset:
Shape optimization for surface functionals in Navier-Stokes flow using a phase field approach
Authors: Garcke Harald , Hecht Claudia , Hinze Michael , Kahle Christian , Lam Kei Fong
Published: September 2016

We consider shape and topology optimization of an object in fluid flow governed by the Navier–Stokes equations. Shapes are modelled with the help of a phase field approach and the solid body is relaxed to be a porous medium. The phase field method uses a Ginzburg–Landau functional in order to approximate a perimeter penalization. We focus on surface functionals and carefully introduce a new modelling variant, show existence of minimizers and derive first order necessary conditions. These conditions are related to classical shape derivatives by identifying the sharp interface limit with the help of formally matched asymptotic expansions. Finally, we present numerical computations based on a Cahn–Hilliard type gradient descent which demonstrate that the method can be used to solve shape optimization problems for fluids with the help of the new approach.
Riesz-Like Bases in Rigged Hilbert Spaces
Authors: Bellomonte Giorgia , Trapani Camillo
Published: September 2016

The notions of Bessel sequence, Riesz-Fischer sequence and Riesz basis are generalized to a rigged Hilbert space

\mathcal D[t] \subset \mathcal H \subset \mathcal D^\times[t^\times]

. A Riesz-like basis, in particular, is obtained by considering a sequence

\{\xi_n\} \subset \mathcal D

which is mapped by a one-to-one continuous operator

T:\mathcal D[t] \to \mathcal H[\| \cdot\|]

into an orthonormal basis of the central Hilbert space

\mathcal H

of the triplet. The operator

T

is, in general, an unbounded operator in

\mathcal H

. If

T

has a bounded inverse then the rigged Hilbert space is shown to be equivalent to a triplet of Hilbert spaces.
Topological Structure of the Spaces of Composition Operators on Hilbert Spaces of Dirichlet Series
Authors: Hu Bingyang , Khoi Le Hai , Zhao Ruhan
Published: September 2016

In this paper we study some topological properties of the space of bounded composition operators on some Hilbert spaces of Dirichlet series. We first obtain formulas for the norms and essential norms of composition operators and differences of composition operators on Hilbert spaces of Dirichlet series. Then we give a characterization of the isolated points in the topological space of bounded composition operators on some Hilbert spaces of Dirichlet series. Finally we obtain sufficient conditions such that two composition operators are in the same path component. We show, among other results, that all compact composition operators are in the same path component. For a certain class of frequencies we give complete description of path components.
On Superposition Operators in Spaces of Regular and of Bounded Variation Functions
Authors: Michalak Artur
Published: September 2016

For a function

f:[0,1]\times \mathbb R \to \mathbb R

we define the superposition operator

\Psi_f: \mathbb R^{[0,1]} \to \mathbb R^{[0,1]}

by the formula

\Psi_f(\varphi)(t)=f(t,\varphi(t))

. First we provide necessary and sufficient conditions for

f

under which the operator

\Psi_f

maps the space

R(0,1)

, of all real regular functions on

[0,1]

, into itself. Next we show that if an operator

\Psi_f

maps the space

BV(0,1)

, of all real functions of bounded variation on

[0,1]

, into itself, then

(1) it maps bounded subsets of

BV(0,1)

into bounded sets if additionally

f

is locally bounded,

(2)

f= f_{cr}+f_{dr}

where the operator

\Psi_{f_{cr}}

maps the space

D(0,1)\cap BV(0,1)

, of all right-continuous functions in

BV(0,1)

, into itself and the operator

\Psi_{f_{dr}}

maps the space

BV(0,1)

into its subset consisting of functions with countable support

(3)

\limsup_{n\to \infty} n^{\frac{1}{2}}|f(t_n,x_n)-f(s_n,x_n)|<\infty

for every bounded sequence

(x_n)\subset \mathbb R

and for every sequence

([s_n,t_n))

of pairwise disjoint intervals in

[0,1]

such that the sequence

(|f(t_n,x_n)-f(s_n,x_n)|)

is decreasing.

Moreover we show that if an operator

\Psi_f

maps the space

D(0,1)\cap BV(0,1)

into itself, then

f

is locally Lipschitz in the second variable uniformly with respect to the first variable.
Stabilization of Viscoelastic Wave Equations with Distributed or Boundary Delay
Authors: Peralta Gilbert
Published: September 2016

The wave equation with viscoelastic boundary damping and internal or boundary delay is considered. The memory kernel is assumed to be integrable and completely monotonic. Under certain conditions on the damping factor, delay factor and the memory kernel it is shown that the energy of the solutions decay to zero either asymptotically or exponentially. In the case of internal delay, the result is obtained through spectral analysis and the Gearhart-Pruss Theorem, whereas in the case of boundary delay, it is obtained using the energy method.
Recurrent Fungal Keratitis and Blepharitis Caused by Aspergillus flavus
Authors: Lee Chia-Yi , Ho Yi-Ju , Sun Chi-Chin , Lin Hsin-Chiung , Hsiao Ching-Hsi , Ma David Hui-Kang , Lai Chi-Chun , Chen Hung-Chi
Published: September 2016

Aspergillus species produces a wide spectrum of fungal diseases like endophthalmitis and fungal keratitis ophthalmologically, but there has been no report about blepharitis caused by Aspergilus flavus to date. Herein, we report a 61-year-old ethnic Han Taiwanese male who had suffered from pain with burning and foreign body sensation after an insect bite on his left eye. Specimens from bilateral eyelids suggested infection of A. flavus, whereas corneal scraping showed the presence of Gram-negative bacteria. He was admitted for treatment of infectious keratitis with topical antibiotic and antifungal eye drops. Two weeks after discharge, recurrent blepharitis and keratitis of A. flavus was diagnosed microbiologically. Another treatment course of antifungal agent was resumed in the following 6 months, without further significant symptoms in the following 2 years. Collectively, it is possible for A. flavus to induce concurrent keratitis and blepharitis, and combined treatment of keratitis as well as blepharitis is advocated for as long as 6 months to ensure no recurrence.
Seasonal variation of atmospheric particle number concentrations, new
particle formation and atmospheric oxidation capacity at the high Arctic
site Villum Research Station, Station Nord
Authors: Nguyen Quynh T. , Glasius Marianne , Sørensen Lise L. , Jensen Bjarne , Skov Henrik , Birmili Wolfram , Wiedensohler Alfred , Kristensson Adam , Nøjgaard Jacob K. , Massling Andreas
Published: September 2016

Abstract. This work presents an analysis of the physical properties of sub-micrometer aerosol particles measured at the high Arctic site Villum Research Station, Station Nord (VRS), northeast Greenland, between July 2010 and February 2013. The study focuses on particle number concentrations, particle number size distributions and the occurrence of new particle formation (NPF) events and their seasonality in the high Arctic, where observations and characterization of such aerosol particle properties and corresponding events are rare and understanding of related processes is lacking.A clear accumulation mode was observed during the darker months from October until mid-May, which became considerably more pronounced during the prominent Arctic haze months from March to mid-May. In contrast, nucleation- and Aitken-mode particles were predominantly observed during the summer months. Analysis of wind direction and wind speed indicated possible contributions of marine sources from the easterly side of the station to the observed summertime particle number concentrations, while southwesterly to westerly winds dominated during the darker months. NPF events lasting from hours to days were mostly observed from June until August, with fewer events observed during the months with less sunlight, i.e., March, April, September and October. The results tend to indicate that ozone (O3) might be weakly anti-correlated with particle number concentrations of the nucleation-mode range (10–30 nm) in almost half of the NPF events, while no positive correlation was observed. Calculations of air mass back trajectories using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model for the NPF event days suggested that the onset or interruption of events could possibly be explained by changes in air mass origin. A map of event occurrence probability was computed, indicating that southerly air masses from over the Greenland Sea were more likely linked to those events.
Scalar turbulent behavior in the roughness sublayer of an Amazonian forest
Authors: Zahn Einara , Dias Nelson L. , Araújo Alessandro , Sá Leonardo D. A. , Sörgel Matthias , Trebs Ivonne , Wolff Stefan , Manzi Antônio
Published: September 2016

Abstract. An important current problem in micrometeorology is the characterization of turbulence in the roughness sublayer (RSL), where most of the measurements above tall forests are made. There, scalar turbulent fluctuations display significant departures from the predictions of Monin–Obukhov similarity theory (MOST). In this work, we analyze turbulence data of virtual temperature, carbon dioxide, and water vapor in the RSL above an Amazonian forest (with a canopy height of 40 m), measured at 39.4 and 81.6 m above the ground under unstable conditions. We found that dimensionless statistics related to the rate of dissipation of turbulence kinetic energy (TKE) and the scalar variance display significant departures from MOST as expected, whereas the vertical velocity variance follows MOST much more closely. Much better agreement between the dimensionless statistics with the Obukhov similarity variable, however, was found for the subset of measurements made at a low zenith angle Z, in the range 0°  <  |Z|  <  20°. We conjecture that this improvement is due to the relationship between sunlight incidence and the “activation–deactivation” of scalar sinks and sources vertically distributed in the forest. Finally, we evaluated the relaxation coefficient of relaxed eddy accumulation: it is also affected by zenith angle, with considerable improvement in the range 0°  <  |Z|  <  20°, and its values fall within the range reported in the literature for the unstable surface layer. In general, our results indicate the possibility of better stability-derived flux estimates for low zenith angle ranges.
Global carbonyl sulfide (OCS) measured by MIPAS/Envisat during 2002–2012
Authors: Glatthor Norbert , Höpfner Michael , Leyser Adrian , Stiller Gabriele P. , von Clarmann Thomas , Grabowski Udo , Kellmann Sylvia , Linden Andrea , Sinnhuber Björn-Martin , Krysztofiak Gisele , Walker Kaley A.
Published: September 2016

Abstract. We present a global OCS data set covering the period June 2002 to April 2012, derived from FTIR limb emission spectra measured with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on the ENVISAT satellite. The vertical resolution is 4–5 km in the height region 6–15 km and 15 km at 40 km altitude. The total estimated error amounts to 40–50 pptv between 10 and 20 km and to 120 pptv at 40 km altitude. MIPAS OCS data show no systematic bias with respect to balloon observations, with deviations mostly below ±50 pptv. However, they are systematically higher than the OCS volume mixing ratios of the ACE-FTS instrument on SCISAT, with maximum deviations of up to 100 pptv in the altitude region 13–16 km. The data set of MIPAS OCS exhibits only moderate interannual variations and low interhemispheric differences. Average concentrations at 10 km altitude range from 480 pptv at high latitudes to 500–510 pptv in the tropics and at northern mid-latitudes. Seasonal variations at 10 km altitude amount up to 35 pptv in the northern and up to 15 pptv in the southern hemisphere. Northern hemispheric OCS abundances at 10 km altitude peak in June in the tropics and around October at high latitudes, while the respective southern hemispheric maxima were observed in July and in November. Global OCS distributions at 250 hPa (~ 10–11 km) show enhanced values at low latitudes, peaking during boreal summer above the western Pacific and the Indian Ocean, which indicates oceanic release. Further, a region of depleted OCS amounts extending from Brazil to central and southern Africa was detected at this altitude, which is most pronounced in austral summer. This depletion is related to seasonally varying vegetative uptake by the tropical forests. Typical signatures of biomass burning like the southern hemispheric biomass burning plume are not visible in MIPAS data, indicating that this process is only a minor source of tropospheric OCS. At the 150 hPa level (~ 13–14 km) enhanced amounts of OCS were also observed inside the Asian Monsoon Anticyclone, but this enhancement is not especially outstanding as compared to other low latitude regions at the same altitude. At the 80 hPa level (~ 17–18 km) equatorward transport of mid-latitude air masses containing lower OCS amounts around the summertime anticyclones was observed. A significant trend could not be detected in tropospheric MIPAS OCS amounts, which points to globally balanced sources and sinks.
New-generation NASA Aura Ozone Monitoring Instrument (OMI) volcanic SO2 dataset: Algorithm description, initial results, and continuation with the Suomi-NPP Ozone Mapping and Profiler Suite (OMPS)
Authors: Li Can , Krotkov Nickolay A. , Carn Simon , Zhang Yan , Spurr Robert J. D. , Joiner Joanna
Published: September 2016

Abstract. Since the fall of 2004, the Ozone Monitoring Instrument (OMI) has been providing global monitoring of volcanic SO2 emissions, helping to understand their climate impacts and to mitigate aviation hazards. Here we introduce a new generation OMI volcanic SO2 dataset based on a principal component analysis (PCA) retrieval technique. To reduce retrieval noise and artifacts as seen in the current operational linear fit (LF) algorithm, the new algorithm, OMSO2VOLCANO, uses characteristic features extracted directly from OMI radiances in the spectral fitting, thereby helping to minimize interferences from various geophysical processes (e.g., O3 absorption) and measurement details (e.g., wavelength shift). To solve the problem of low bias for large SO2 total columns in the LF product, the OMSO2VOLCANO algorithm employs a table lookup approach to estimate SO2 Jacobians (i.e., the instrument sensitivity to a perturbation in the SO2 column amount) and iteratively adjusts the spectral fitting window to exclude shorter wavelengths where the SO2 absorption signals are saturated. To first order, the effects of clouds and aerosols are accounted for using a simple Lambertian equivalent reflectivity approach. As with the LF algorithm, OMSO2VOLCANO provides total column retrievals based on a set of pre-defined SO2 profiles from the lower troposphere to the lower stratosphere, including a new profile peaked at 13 km for plumes in the upper troposphere. Examples given in this study indicate that the new dataset shows significant improvement over the LF product, with at least 50 % reduction in retrieval noise over the remote Pacific. For large eruptions such as Kasatochi in 2008 (~ 1700 kt total SO2) and Sierra Negra in 2005 (> 1100 DU maximal SO2), OMSO2VOLCANO generally agrees well with other algorithms that also utilize the full spectral content of satellite measurements, while the LF algorithm tends to underestimate SO2. We also demonstrate that, despite the coarser spatial and spectral resolution of the Suomi National Polar-orbiting Partnership (Suomi-NPP) Ozone Mapping and Profiler Suite (OMPS) instrument, application of the new PCA algorithm to OMPS data produces highly consistent retrievals between OMI and OMPS. The new PCA algorithm is therefore capable of continuing the volcanic SO2 data record well into the future using current and future hyperspectral UV satellite instruments.
Current sheet flapping in the near-Earth magnetotail: peculiarities of propagation and parallel currents
Authors: Yushkov Egor V. , Artemyev Anton V. , Petrukovich Anatoly A. , Nakamura Rumi
Published: September 2016

Abstract. We consider series of tilted current sheet crossings, corresponding to flapping waves in the near-Earth magnetotail. We analyse Cluster observations from 2005 to 2009, when spacecraft visited the magnetotail neutral plane near X ∈ [ − 17,  − 8], Y ∈ [ − 16,  − 2] RE (in the GSM system). Large separation of spacecraft allows us to estimate both local and global properties of flapping current sheets. We find significant variation in flapping wave direction of propagation between the middle tail and flanks. Th series of tilted current sheets represent the system of periodic, almost parallel currents with typical thickness of current filaments about L = 0.4 RE. The earthward gradients of Bz magnetic field are reduced within this current system in comparison with the gradients in the quiet near-Earth magnetotail. The wavelength (i.e. a distance between two crossings of current sheets with the same orientations) of the flapping waves is larger than 2πL for most of observations. The velocity of flapping wave propagation is about ion bulk velocity and is significantly lower than the velocity of ion drift relative to electrons. We discuss possible drivers of flapping and estimate the amplitude of the total parallel current generated by flapping waves.
Reviews and syntheses: Australian vegetation phenology: new insights from satellite remote sensing
and digital repeat photography
Authors: Moore Caitlin E. , Brown Tim , Keenan Trevor F. , Duursma Remko A. , van Dijk Albert I. J. M. , Beringer Jason , Culvenor Darius , Evans Bradley , Huete Alfredo , Hutley Lindsay B. , Maier Stefan , Restrepo-Coupe Natalia , Sonnentag Oliver , Specht Alison , Taylor Jeffrey R. , van Gorsel Eva , Liddell Michael J.
Published: September 2016

Abstract. Phenology is the study of periodic biological occurrences and can provide important insights into the influence of climatic variability and change on ecosystems. Understanding Australia's vegetation phenology is a challenge due to its diverse range of ecosystems, from savannas and tropical rainforests to temperate eucalypt woodlands, semi-arid scrublands, and alpine grasslands. These ecosystems exhibit marked differences in seasonal patterns of canopy development and plant life-cycle events, much of which deviates from the predictable seasonal phenological pulse of temperate deciduous and boreal biomes. Many Australian ecosystems are subject to irregular events (i.e. drought, flooding, cyclones, and fire) that can alter ecosystem composition, structure, and functioning just as much as seasonal change. We show how satellite remote sensing and ground-based digital repeat photography (i.e. phenocams) can be used to improve understanding of phenology in Australian ecosystems. First, we examine temporal variation in phenology on the continental scale using the enhanced vegetation index (EVI), calculated from MODerate resolution Imaging Spectroradiometer (MODIS) data. Spatial gradients are revealed, ranging from regions with pronounced seasonality in canopy development (i.e. tropical savannas) to regions where seasonal variation is minimal (i.e. tropical rainforests) or high but irregular (i.e. arid ecosystems). Next, we use time series colour information extracted from phenocam imagery to illustrate a range of phenological signals in four contrasting Australian ecosystems. These include greening and senescing events in tropical savannas and temperate eucalypt understorey, as well as strong seasonal dynamics of individual trees in a seemingly static evergreen rainforest. We also demonstrate how phenology links with ecosystem gross primary productivity (from eddy covariance) and discuss why these processes are linked in some ecosystems but not others. We conclude that phenocams have the potential to greatly improve the current understanding of Australian ecosystems. To facilitate the sharing of this information, we have formed the Australian Phenocam Network (http://phenocam.org.au/).
Long-distance electron transport occurs globally in marine sediments
Authors: Burdorf Laurine D. W. , Tramper Anton , Seitaj Dorina , Meire Lorenz , Hidalgo-Martinez Silvia , Zetsche Eva-Maria , Boschker Henricus T. S. , Meysman Filip J. R.
Published: September 2016

Abstract. Recently, long filamentous bacteria have been reported to conduct electrons over centimetre distances in marine sediments. These so-called cable bacteria perform a novel "electrogenic" form of sulfur oxidation, whereby long-distance electron transport links sulfide oxidation in deeper sediment horizons to oxygen reduction in the upper millimetres of the sediment. Electrogenic sulfur oxidation exerts a strong impact on the sediment biogeochemistry, but it is currently unknown how prevalent the process is within the seafloor. Here we provide a state-of-the-art assessment of its global distribution by combining new field observations with previous reports from literature. This synthesis demonstrates that electrogenic sulfur oxidation mediated by long-distance electron transport is a widespread phenomenon in the present-day seafloor. The process is found in different oceanographic regions and climate zones (The Netherlands, Greenland, USA, Australia), and thrives in a range of different coastal habitats (estuaries, salt marshes, mangroves, coastal hypoxic basins, intertidal flats). The combination of a widespread occurrence and a strong local geochemical imprint suggests that electrogenic sulfur oxidation could be an important, and hitherto overlooked, component of the marine cycle of carbon, sulfur and other elements.
From Monsoon to marine productivity in the Arabian Sea: insights
from glacial and interglacial climates
Authors: Le Mézo Priscilla , Beaufort Luc , Bopp Laurent , Braconnot Pascale , Kageyama Masa
Published: September 2016

Abstract. The Indian monsoon is known to boost biological productivity in the Arabian Sea. This paradigm has been extensively used to reconstruct past monsoon variability from paleo-proxies indicative of changes in surface productivity. Here, we test this paradigm by simulating changes in marine primary productivity for 8 contrasted climates from the last glacial-interglacial cycle. We show that there is no straightforward correlation between boreal summer productivity of the western and central Arabian Sea and summer monsoon strength across the different simulated climates. Locally, productivity is fueled by nutrient supply driven by Ekman dynamics depending on both wind stress and wind stress curl. In our simulations, a stronger monsoon with intensified wind stress on the Arabian Sea can lead to either increased or reduced productivity depending on the exact ocean surface on which increased wind stress and a positive wind stress curl are acting. The effects of winds onto the ocean are modulated by the Indian summer monsoon intensity and pattern (e.g. position of the low-level jet over the Arabian Sea), which in turn are driven by the orbital parameters and the ice sheet cover. The orbital parameters are indeed shown to impact wind stress intensity in the Arabian Sea through large scale changes in the meridional gradient of upper tropospheric temperature. But both the orbital parameters and the ice sheets affects the pattern of wind stress curl through the position of the sea level depression barycentre over the monsoon region (20° W–150° W, 30° S–60° N). The combined changes in monsoon intensity and pattern lead to higher glacial productivity during the summer season, in agreement with some paleo-productivity reconstructions.
An axisymmetric non-hydrostatic model for
double-diffusive water systems
Authors: Hilgersom Koen , Zijlema Marcel , van de Giesen Nick
Published: September 2016

Abstract. The three-dimensional (3-D) modelling of water systems involving double-diffusive processes is challenging due to the large computation times required to solve the flow and transport of constituents. In systems that approach axisymmetry around a central location, computation times can be reduced by applying a quasi 3-D axisymmetric model setup. This article applies the Navier-Stokes equations described in cylindrical coordinates, and integrates them to guarantee mass and momentum conservation. The discretized equations are presented in a way that a Cartesian finite volume model can be easily extended to this quasi 3-D framework, which is demonstrated by the implementation into a non-hydrostatic free-surface flow model. This model employs temperature and salinity dependent densities, molecular diffusivities, and kinematic viscosity. Four qualitative case studies demonstrate a good behaviour with respect to expected density and diffusivity driven flow and stratification in shallow water bodies. A fifth case study involves a new validation method that quantifies the radial expansion of a dense water layer developing from a central inflow at the bottom of a shallow water body.
Recent trends and variability in river discharge across northern
Canada
Authors: Déry Stephen J. , Stadnyk Tricia  A. , MacDonald Matthew  K. , Gauli-Sharma Bunu
Published: September 2016

Abstract. This study presents an analysis of the observed interannual variability and interdecadal trends in river discharge across northern Canada for 1964–2013. The 42 rivers chosen for this study span a combined gauged area of 5.26 × 106 km2 and are selected based on data availability and quality, gauged area, and record length. Interannual variability in river discharge is greatest for the Eastern Arctic Ocean (coefficient of variation CV = 16 %) due to the Caniapiscau River diversion into the La Grande Rivière system for enhanced hydropower production. Variability is lowest for the study area as a whole (CV = 7 %). Based on the Mann-Kendall Test (MKT), no significant (p > 0.05) trend in annual discharge from 1964–2013 is observed to the Bering Sea, Western Arctic Ocean, Western Hudson and James Bay, and Labrador Sea; for northern Canada as a whole, however, a statistically-significant (p
Grounding and calving cycle of Mertz Ice Tongue revealed by shallow Mertz Bank
Authors: Wang Xianwei , Holland David M. , Cheng Xiao , Gong Peng
Published: September 2016

Abstract. A recent study, using remote sensing, provided evidence that a seafloor shoal influenced the 2010 calving event of the Mertz Ice Tongue (MIT), by partially grounding the MIT several years earlier. In this paper, we start by proposing a method to calculate firn air content (FAC) around Mertz from seafloor-touching icebergs. Our calculations indicate the FAC around Mertz region as 4.87 ± 1.31 m. We then design an indirect method of using freeboard and sea surface height data extracted from ICESat/GLAS, FAC, and relatively accurate seafloor topography to detect grounding sections of the MIT between 2002 and 2008 and analyze the process of grounding prior to the calving event. By synthesizing remote sensing data, we point out that the grounding position was localized northeast of the Mertz ice front close to the Mertz Bank. The grounding outlines of the tongue caused by the Mertz Bank are extracted as well. From 2002 to 2008, the grounding area increased and the grounding became more pronounced. Additionally, the ice tongue could not effectively climb over the Mertz Bank in following the upstream ice flow direction and that is why MIT rotated clockwise after late 2002. Furthermore, we demonstrate that the area-increasing trend of the MIT changed little after calving (∼  36 km2 a−1), thus allowing us to use remote sensing to estimate the elapsed time until the MIT can reground on and be bent by the shoal. This period is approximately 70 years. Our observations suggest that the calving of the MIT is a cyclical process controlled by the presence of the shallow Mertz Bank location and the flow rate of the tongue. This calving cycle also explains the cyclic variations in sea-surface conditions around the Mertz detected by earlier studies.
Estimating the wake deflection downstream of a wind turbine in different atmospheric stabilities: an LES study
Authors: Vollmer Lukas , Steinfeld Gerald , Heinemann Detlev , Kühn Martin
Published: September 2016

Abstract. An intentional yaw misalignment of wind turbines is currently discussed as one possibility to increase the overall energy yield of wind farms. The idea behind this control is to decrease wake losses of downstream turbines by altering the wake trajectory of the controlled upwind turbines. For an application of such an operational control, precise knowledge about the inflow wind conditions, the magnitude of wake deflection by a yawed turbine and the propagation of the wake is crucial. The dependency of the wake deflection on the ambient wind conditions as well as the uncertainty of its trajectory are not sufficiently covered in current wind farm control models. In this study we analyze multiple sources that contribute to the uncertainty of the estimation of the wake deflection downstream of yawed wind turbines in different ambient wind conditions. We find that the wake shapes and the magnitude of deflection differ in the three evaluated atmospheric boundary layers of neutral, stable and unstable thermal stability. Uncertainty in the wake deflection estimation increases for smaller temporal averaging intervals. We also consider the choice of the method to define the wake center as a source of uncertainty as it modifies the result. The variance of the wake deflection estimation increases with decreasing atmospheric stability. Control of the wake position in a highly convective environment is therefore not recommended.
Parents, Schools and Financial Crisis in Contemporary Greece
Authors: Zachos Dimitris
Published: September 2016

The purpose of this grounded theory study is to draw on the experiences and views of primary school board members of Parents and Guardians Associations of Thessaloniki’s and to explore the ways they deal with issues occurred after financial crisis in Greece began. Three research questions related to the aims of our study were posed: First, what are the research participants’ incentives for becoming board members of Association of Parents & Guardians? Second, how these institutions work under current circumstances and what are the ultimate goals? Third, what are the attitudes and practices of the individuals who took part in our research towards issues of social justice in education? Data were collected through twenty semi-structured interviews and analyzed through Grounded Theory design. As our data suggests, board members of Associations of Parents & Guardians regard social justice issues as important; they appear to be active in taking steps and implementing measures aimed at empowering students in need; they allocate financial resources to low-income pupils and have deep faith of equity in education.
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CHIRONOMID FAUNA OF THE RIVER ANGARA
Authors: Erbaeva E. A.
Published: September 2016

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Concurrent use of endourological and radiologic methods in the management of high-grade renal trauma
Authors: Akbari Ardalan , Heran Manraj K.S. , Afshar Kourosh
Published: September 2016

This case report explores the efficacy of simultaneous use of endourological and radiological methods to assess and manage high-grade renal trauma. A male rugby player was diagnosed with Grade 4 blunt renal trauma. A segment of the patient’s kidney was isolated from the main renal pelvis with intact perfusion. This resulted in urinary extravasation. Ureteral stenting and angioembolization were used to treat the patient’s severe symptoms. Angioembolization ablated functional tissue that was causing a persistent urinary leak. Following the treatment, the patient was discharged with no significant bleeding or leakage from the kidney. This report illustrates an uncommon use of this combined approach. Followup 18 months post-trauma revealed normal blood pressure and approximately 30% loss of volume of the affected kidney.
Isolated thrombosis of right spermatic vein with underlying Factor V Leiden mutation
Authors: Bolat Deniz , Gunlusoy Bulent , Yarimoglu Serkan , Ozsinan Funda , Solmaz Serife , Imamoglu Fatma Gul
Published: September 2016

Spermatic vein thrombosis is a very uncommon clinical entity. Most cases involve the left side. Herein, we present an unusual case of a young man who presented with spermatic vein thrombosis on the right side with an underlying Factor V Leiden mutation. To our knowledge, it is the first case in the literature.
Multidisciplinary approach to giant paratesticular liposarcoma
Authors: Sopeña-Sutil Raquel , Silan Francesco , Butron-Vila Maria Teresa , Guerrero-Ramos Felix , Lagaron-Comba Emilio , Passas-Martinez Juan
Published: September 2016

Primary paratesticular tumours are very rare and the spermatic cord (SCT) is the most frequent site of origin, with 20% of malignancy. Although liposarcoma is the most frequent histotype (46.6 %), less than 200 cases have been reported in the literature.

We report the case of a 56-year-old man who presented a giant scrotal mass of 25 years of evolution and measuring 40 x 40 cm. It could be considered the greatest paratesticular liposarcoma described to date. Computed tomogaphy (CT) revealed mass features consistent with liposarcoma and the simultaneous presence of bilateral inguinal hernia with bladder involvement. A multidisciplinary approach was taken to remove the mass, solve the hernia, and provide functional results.
Young Brazilian Children’s Emotion Understanding: A Comparison within and across Cultures
Authors: Karstad Silja B. , Vikan Arne , Berg-Nielsen Turid S. , Lucena Moreira Pollyana de , De Abreu Eloá Losano , Rique Júlio
Published: September 2016

Research on children’s Emotion Understanding (EU) has been dominated by middle-class samples from Western societies. We studied cultural and Socioeconomic Status (SES) variation in young children’s EU in a high SES sample (n = 50) and a low SES sample (n = 50) of Brazilian preschoolers using the Test of Emotion Comprehension. We found that the high SES sample performed better at both the overall and component levels than the low SES sample on EU. The differences were especially substantial for the recognition of basic emotions, with the low SES children recognizing negative emotions better than positive and neutral emotions. In addition, we compared the two SES samples of Brazilian children to same-age samples from Norway, Italy and Peru. Between the Brazilian and the European samples and the Brazilian and other non-European samples, the variation in EU was observed to be more related to SES than to culture.
A new genus and species of axiid shrimp (Crustacea, Decapoda) from a southwestern Indian Ocean seamount
Authors: Dworschak Peter C.
Published: September 2016

A new genus and species of axiid shrimp, Montanaxius mediumquod gen. et sp. nov., is described and illustrated based on three specimens collected from hexactinellid sponges from a seamount in the southwest Indian Ocean. The new genus is characterized by a laterally denticulate rostrum, short lateral carina, absence of submedian carina, a prominent toothed median carina, round pleomere pleura 2–5, pleurobranchs on second to fourth pereopods, and the presence of a male first pleopod and appendix interna on pleopods 3–5. It most closely resembles Levantocaris Galil & Clark, 1993 and Planaxius Komai & Tachikawa, 2008, but differs from the former by being gonochoristic, having a strongly elevated gastric region and well-developed eyes, and from the latter by its toothed median carina and the presence of a median telson spine.
The Koszul dual of the ring of three commuting matrices
Authors: Hreinsdóttir Freyja
Published: September 2016

Let $X=(x_{ij}), Y=(y_{ij})$ and $Z=(z_{ij})$ be generic $n$ by $n$ matrices. Let $k$ be a field with char $k\neq 2, 3, S=k[x_{11}, \dots , x_{nn}, y_{11}, \dots , y_{nn}, z_{11}, \dots , z_{nn}] $ and let $I$ be the ideal generated by the entries of the matrices $XY-YX, XZ-ZX$ and $YZ-ZY$. We study the Koszul dual of the ring $R=S/I$ and show that for $n\geq 3$ this is the enveloping algebra of a nilpotent Lie algebra. We also give the dimension of the Lie algebra in each degree.
Complex interpolation of a Banach space with its dual
Authors: Watbled Frédérique
Published: September 2016

Let $X$ be a Banach space compatible with its antidual $\overline{X^*}$, where $\overline{X^*}$ stands for the vector space $X^*$ where the multiplication by a scalar is replaced by the multiplication $\lambda \odot x^* = \overline{\lambda} x^*$. Let $H$ be a Hilbert space intermediate between $X$ and $\overline{X^*}$ with a scalar product compatible with the duality $(X,X^*)$, and such that $X \cap \overline{X^*}$ is dense in $H$. Let $F$ denote the closure of $X \cap \overline{X^*}$ in $\overline{X^*}$ and suppose $X \cap \overline{X^*}$ is dense in $X$. Let $K$ denote the natural map which sends $H$ into the dual of $X \cap F$ and for every Banach space $A$ which contains $X \cap F$ densely let $A'$ be the realization of the dual space of $A$ inside the dual of $X \cap F$. We show that if $\vert \langle K^{-1}a, K^{-1}b \rangle_H \vert \leq \parallel a \parallel_{X'} \parallel b \parallel_{F'}$ whenever $a$ and $b$ are both in $X' \cap F'$ then $(X, \overline{X^*})_{\frac12} = H$ with equality of norms. In particular this equality holds true if $X$ embeds in $H$ or $H$ embeds densely in $X$. As other particular cases we mention spaces $X$ with a $1$-unconditional basis and Köthe function spaces on $\Omega$ intermediate between $L^1(\Omega)$ and $L^\infty(\Omega)$.
Some characterizations of the properties (DN) and ($\tilde\Omega$)
Authors: Hai Le Mau , Van Khue Nguyen
Published: September 2016

The aim of this paper is to show that 7816H_w(B,F) = H(B,F)7816 for every $\mathrm{LB}^\infty$-regular compact set $B$ in a Frechet space $E$ if and only if $F$ is a Frechet space having property (DN). At the same time, the equivalence between the existence of the $\mathrm{LB}^\infty$-regular compact set $B$ in a Schwartz-Frechet space $E$ with an absolute basis and the property $(\tilde\Omega)$ also established here.
On Morita's fundamental theorem for $C^*$-algebras
Authors: Blecher David P.
Published: September 2016

We give a solution, via operator spaces, of an old problem in the Morita equivalence of $C^*$-algebras. Namely, we show that $C^*$-algebras are strongly Morita equivalent in the sense of Rieffel if and only if their categories of left operator modules are isomorphic via completely contractive functors. Moreover, any such functor is completely isometrically isomorphic to the Haagerup tensor product (= interior tensor product) with a strong Morita equivalence bimodule. An operator module over a $C^*$-algebra $\mathcal A$ is a closed subspace of some B(H) which is left invariant under multiplication by $\pi(\mathcal\ A)$, where $\pi$ is a*-representation of $\mathcal A$ on $H$. The category $_{\mathcal{AHMOD}}$ of *-representations of $\mathcal A$ on Hilbert space is a full subcategory of the category $_{\mathcal{AOMOD}}$ of operator modules. Our main result remains true with respect to subcategories of $OMOD$ which contain $HMOD$ and the $C^*$-algebra itself. It does not seem possible to remove the operator space framework; in the very simplest cases there may exist no bounded equivalence functors on categories with bounded module maps as morphisms (as opposed to completely bounded ones). Our proof involves operator space techniques, together with a $C^*$-algebra argument using compactness of the quasistate space of a $C^*$-algebra, and lowersemicontinuity in the enveloping von Neumann algebra.
On equivalence of semigroup identities
Authors: Macedońska O. , Żabka M.
Published: September 2016

For a given relation $\rho$ on a free semigroup ${\mathcal F}$ we describe the smallest cancellative fully invariant congruence ${\rho}^{\sharp}$ containing $\rho$. Two semigroup identities are s-equivalent if each of them is a consequence of the other on cancellative semigroups. If two semigroup identities are equivalent on groups, it is not known if they are s-equivalent. We give a positive answer to this question for all binary semigroup identities of the degree less or equal to 5. A poset of corresponding varieties of groups is given.
Gradient vector fields which characterize warped products
Authors: Innami Nobuhiro , Kim Byung Hak
Published: September 2016

We find what condition on gradient vector fields characterizes warped products, Riemannian products and round spheres. To do this we apply the theory of Jacobi equations without conjugate points to the differential maps of the local one-parameter groups generated by gradient vector fields.
Doubling for general sets
Authors: Buckley Stephen M. , Hanson Bruce , MacManus Paul
Published: September 2016

We investigate doubling conditions defined in terms of measurable bounded sets and find a simple characterization of quasisymmetrically thick Cantor sets on the line.
Fock representation of the binary shift algebra
Authors: Vik Sigmund
Published: September 2016

We modify the Fock representation construction of the CAR-algebra to obtain a new proof for that the Binary Shift Algebra is isomorphic to the CAR-algebra.
Linear syzygies of Stanley-Reisner ideals
Authors: Reiner V , Welker V
Published: September 2016

We give an elementary description of the maps in the linear strand of the minimal free resolution of a square-free monomial ideal, that is, the Stanley-Reisner ideal associated to a simplicial complex $\Delta$. The description is in terms of the homology of the canonical Alexander dual complex $\Delta^*$. As applications we are able to prove for monomial ideals and $j=1$ a conjecture of J. Herzog giving lower bounds on the number of $i$-syzygies in the linear strand of $j^{th}$-syzygy modules show that the maps in the linear strand can be written using only $\pm 1$ coefficients if $\Delta^*$ is a pseudomanifold exhibit an example where multigraded maps in the linear strand cannot be written using only $\pm 1$ coefficients compute the entire resolution explicitly when $\Delta^*$ is the complex of independent sets of a matroid
Koszul property for points in projective spaces
Authors: Conca Aldo , Trung Ngô Viêt , Valla Giuseppe
Published: September 2016

A graded $K$-algebra $R$ is said to be Koszul if the minimal $R$-free graded resolution of $K$ is linear. In this paper we study the Koszul property of the homogeneous coordinate ring $R$ of a set of $s$ points in the complex projective space $\boldsymbol P^n$. Kempf proved that $R$ is Koszul if $s\leq 2n$ and the points are in general linear position. If the coordinates of the points are algebraically independent over $\boldsymbol Q$, then we prove that $R$ is Koszul if and only if $s\le 1 +n + n^2/4$. If $s\le 2n$ and the points are in linear general position, then we show that there exists a system of coordinates $x_0,\dots,x_n$ of $\boldsymbol P^n$ such that all the ideals $(x_0,x_1,\dots,x_i)$ with $0\le i \le n$ have a linear $R$-free resolution.
The Nevanlinna parametrization for a matrix moment problem
Authors: Lopez-Rodriguez Pedro
Published: September 2016

We obtain the Nevanlinna parametrization for an indeterminate matrix moment problem, giving a homeomorphism between the set $V$ of solutions to the matrix moment problem and the set $\mathcal V$ of analytic matrix functions in the upper half plane such that $V(\lambda )^*V(\lambda )\le I$. We characterize the N-extremal matrices of measures (those for which the space of matrix polynomials is dense in their $L^2$-space) as those whose corresponding matrix function $V(\lambda )$ is a constant unitary matrix.
Extremal graphs of order dimension 4
Authors: Agnarsson Geir
Published: September 2016

We study the maximal number of edges of a graph on $p$ vertices of order dimension 4. We will show that the lower bound for this number is greater than $\frac{3}{8}p^{2} + 2p - 13$. In particular the Turn-4 graph on $p$ vertices does not have the maximal number of edges among the graphs of order dimension 4.
Factors of Toeplitz flows and other almost 1-1 extensions over group rotations
Authors: Downarowicz T. , Durand F.
Published: September 2016

If a minimal topological flow admits a symbolic extension then it also admits a symbolic almost 1-1 extension. The factors of symbolic almost automorphic flows are characterized as those almost automorphic flows which admit a symbolic extension. As an application, we provide concrete examples of factors of Toeplitz flows, which are neither Toeplitz flows nor odometers.
On the number of Euler trails in directed graphs
Authors: Jonsson Jakob
Published: September 2016

Let $G$ be an Eulerian digraph with all in- and out-degrees equal to 2, and let $\pi$ be an Euler trail in $G$. We consider an intersection matrix $\boldsymbol {L}(\pi)$ with the property that the determinant of $\boldsymbol{L}(\pi) + \boldsymbol{I}$ is equal to the number of Euler trails in $G$; $\boldsymbol{I}$ denotes the identity matrix. We show that if the inverse of $\boldsymbol{L}(\pi)$ exists, then $\boldsymbol{L}^{-1}(\pi) = \boldsymbol{L}(\sigma)$ for a certain Euler trail $\sigma$ in $G$. Furthermore, we use properties of the intersection matrix to prove some results about how to divide the set of Euler trails in a digraph into smaller sets of the same size.
A smoothly bounded domain in a complex surface with a compact quotient
Authors: Cheung Wing Sum , Fu Siqi , Krantz Steven G. , Wong Bun
Published: September 2016

We study the classification of smoothly bounded domains in complex manifolds that cover compact sets. We prove that a smoothly bounded domain in a hyperbolic complex surface that covers a compact set is either biholomorphic to the ball or covered by the bidisc.
On the Horn system of partial differential equations and series of hypergeometric type
Authors: Sadykov T. M.
Published: September 2016

The paper deals with the Horn system of hypergeometric differential equations. We consider the associated $\mathcal{D}$-module and construct an explicit basis in the space of holomorphic solutions to the Horn system under some assumptions on its parameters.
Compact measures and measurable weak sections
Authors: Rinkewitz Werner
Published: September 2016

Compact measures, i.e. measures that are inner-regular with respect to a compact family of sets, are related to measurable weak sections in the same way as semicompact measures are related to disintegration. This enables us to prove several stability properties of the class of compact measures. E.g., a countable sum of compact measures is compact; the image $\nu$ of a compact measure $\mu$ is compact provided $\mu$ is an extremal preimage measure of $\nu$. As a consequence, we show that every tight Baire measure is compact.
A compactification of the space of twisted cubics
Authors: Vainsencher I. , Xavier F.
Published: September 2016

We give an elementary, explicit smooth compactification of a parameter space for the family of twisted cubics. The construction also applies to the family of subschemes defined by determinantal nets of quadrics, e.g., cubic ruled surfaces in $\boldsymbol P^4$, Segre varieties in $\boldsymbol P^5$. It is suitable for applications of Bott's formula to a few enumerative problems.
Random Euclidean sections of some classical Banach spaces
Authors: Gordon Y. , Guédon O. , Meyer M. , Pajor A.
Published: September 2016

Using probabilistic arguments, we give precise estimates of the Banach-Mazur distance of subspaces of the classical $\ell_q^n$ spaces and of Schatten classes of operators $S_q^n$ for $q \ge 2$ to the Euclidean space. We also estimate volume ratios of random subspaces of a normed space with respect to subspaces of quotients of $\ell_q$. Finally, the preceeding methods are applied to give estimates of Gelfand numbers of some linear operators.
Prestable ideals and Sagbi bases
Authors: Ohsugi Hidefumi , Hibi Takayuki
Published: September 2016

In order to find a reasonable class of squarefree monomial ideals $I$ for which the toric ideal of the Rees algebra of $I$ has a quadratic Gröbner basis, the concept of prestable ideals will be introduced. Prestable ideals arising from finite pure posets together with their application to Sagbi bases will be discussed.