87,351 research outputs found
Logarithmic L p Bounds for Maximal Directional Singular Integrals in the Plane
No full textLet K be a Calderón-Zygmund convolution kernel on R. We discuss the L p -boundedness of the maximal directional singular integral T V f(x)= sup v ε V | ∫R f(x+t v) K(t)dt|where V is a finite set of N directions. Logarithmic bounds (for 2≤p<∞) are established for a set V of arbitrary structure. Sharp bounds are proved for lacunary and Vargas sets of directions. The latter include the case of uniformly distributed directions and the finite truncations of the Cantor set. We make use of both classical harmonic analysis methods and product-BMO based time-frequency analysis techniques. As a further application of the latter, we derive an L p almost orthogonality principle for Fourier restrictions to cones. © 2012 Mathematica Josephina, Inc
Endpoint Bounds for the Quartile Operator
No full textIt is a result by Lacey and Thiele (Ann. of Math. (2) 146(3):693-724, 1997; ibid. 149(2):475-496, 1999) that the bilinear Hilbert transform maps Lp1(R) × Lp2(R) into Lp1(R) whenever (p1,p2,p3) is a Hölder tuple with p1,p3>1 and p3>2/3. We study the behavior of the quartile operator, which is the Walsh model for the bilinear Hilbert transform, when p3=2/3. We show that the quartile operator maps Lp1(R) × Lp2(R) into L2/3,∞(R) when p1,p2>1 and one component is restricted to subindicator functions. As a corollary, we derive that the quartile operator maps Lp1(R) × Lp2,2/3(R) into L2/3,∞(R). We also provide weak type estimates and boundedness on Orlicz-Lorentz spaces near p1=1,p2=2 which improve, in the Walsh case, the results of Bilyk and Grafakos (J. Geom. Anal. 16 (4):563-584, 2006) and Carro et al. (J. Math. Anal. Appl. 357(2):479-497, 2009). Our main tool is the multi-frequency Calderón-Zygmund decomposition from (Nazarov et al. in Math. Res. Lett. 17(3):529-545, 2010). © 2013 Springer Science+Business Media New York
Development of a European Multi-Model Ensemble System for Seasonal to Inter-Annual Prediction (DEMETER)
No full textA multi-model ensemble-based system for seasonal-to-interannual prediction has been developed in a joint European project known as DEMETER (Development of a European Multimodel Ensemble Prediction System for Seasonal to Interannual Prediction). The DEMETER system comprises seven global atmosphere–ocean coupled models, each running from an ensemble of initial conditions. Comprehensive hindcast evaluation demonstrates the enhanced reliability and skill of the multimodel ensemble over a more conventional single-model ensemble approach. In addition, innovative examples of the application of seasonal ensemble forecasts in malaria and crop yield prediction are discussed. The strategy followed in DEMETER deals with important problems such as communication across disciplines, downscaling of climate simulations, and use of probabilistic forecast information in the applications sector, illustrating the economic value of seasonal-to-interannual prediction for society as a whole
Updated checklist and distribution of the inland-water calanoid copepods (Copepoda: Calanoida) of Romania
No full textNo recent studies on the distribution of calanoid copepods in Romanian inlandwaters
are available. During a long-term survey aimed at large branchiopods, we collected
two diaptomid species that are new for the fauna of the country, and supplemented the
available data on the distribution of other calanoid species with new records. As already
observed in the case of large branchiopods, the habitats of the mountain basins of the Eastern
Carpathians seem to be characterized by a quite distinct species assemblage. The high
calanoid species richness of Romanian inland-waters, and the need for further, more
comprehensive surveys aimed at mapping the actual diversity of this order in Romania are
stressed
Whistler-Mode Waves Observed by the DEMETER Spacecraft and the Kannuslehto Station: Spatial Extent and Propagation to the Ground
No full textAbstract
We use conjugate observations of magnetospheric whistler‐mode waves at frequencies up to 16 kHz by the DEMETER spacecraft (at an altitude of approximately 660 km) and the ground‐based Kannuslehto station in Finland ( ≈ 5.38) to investigate the wave propagation to the ground and their characteristic spatial scales. For this purpose, we evaluate correlations between the wave intensities measured by the spacecraft and the ground‐based station at various frequencies as a function of their longitudinal and L‐shell separations. Two different approaches are used: (a) direct correlation of wave intensities measured at the same times and (b) correlation of wave intensities within corresponding frequency‐time windows, focusing on the identification of the same frequency‐time wave signatures. We show that the characteristic longitudinal scales of the investigated waves are between about 60° and 90°. We further demonstrate that, while the wave intensities measured by DEMETER are generally larger during periods of enhanced geomagnetic activity, wave intensities measured on the ground during increased activity are only slightly larger during the daytime and decrease during the nighttime.Abstract
We use conjugate observations of magnetospheric whistler‐mode waves at frequencies up to 16 kHz by the DEMETER spacecraft (at an altitude of approximately 660 km) and the ground‐based Kannuslehto station in Finland ( ≈ 5.38) to investigate the wave propagation to the ground and their characteristic spatial scales. For this purpose, we evaluate correlations between the wave intensities measured by the spacecraft and the ground‐based station at various frequencies as a function of their longitudinal and L‐shell separations. Two different approaches are used: (a) direct correlation of wave intensities measured at the same times and (b) correlation of wave intensities within corresponding frequency‐time windows, focusing on the identification of the same frequency‐time wave signatures. We show that the characteristic longitudinal scales of the investigated waves are between about 60° and 90°. We further demonstrate that, while the wave intensities measured by DEMETER are generally larger during periods of enhanced geomagnetic activity, wave intensities measured on the ground during increased activity are only slightly larger during the daytime and decrease during the nighttime
Demeter keurmerk voor boomteelt: gewoon beginnen!
No full textVoor biologisch dynamische boomteelt bestaan er in Nederland nog nauwelijks richtlijnen. De auteur beschrijft de Nederlandse boomteeltbedrijven die met biologisch-dynamische principes werken en geeft aan wat er in ieder geval in een Demeter richtlijn zou moeten worden opgenomen
CULT OF DEMETER IN IBERIA-COLCHIS
No full textეძღვნება ივანე ჯავახიშვილის დაბადებიდან 145 წლის იუბილესDemeter – Goddess of the harvest, agriculture, fertility was one of the most worshipped Goddesses in the world of antiquity. From the moment of the appearance of the Greeks in other countries Demeter was identified with the local Goddesses. The given work involves the studies and analyses of the artifacts connected with Demeter’s cult discovered on the territory of Georgia. The results of the study prove that the cult of Demeter was introduced on the territory of Colchis from the period of early antiquity (four terracotta statues were discovered at the Greek necropolis of Kobuleti-Pichvnari and terracotta figurines of pigs, Demeter’s sacred animal were found were found in burials #158,159 of Tsikhisdziri tombs. This is a direct result of the Great Greek colonization since no artefacts proving the existence of cult of Demeter among the local Colchian population have been encountered yet.
The sculpted terracotta head of the Goddess (dated by III-II cc. C.C.) is found at Vani archaeological site, in Hellenistic layers. By the end of the Hellenistic period the cult of Demeter becomes familiar for the population of Eastern Georgia as well (seated terracotta figure is discovered in the hoard of Uplistsikhe, a fragment of a spirelike woman with the covered head is found on the central terrace of Sarkine former city site.
From the late Antiquity Demeter’s cult is widely spread on the territories of both East and West Georgia, which is a result of the existing political situation. It is noteworthy that the images of the goddess are mostly encountered on the glyptic monuments. On the territory of Western Georgia intaglios with symbols connected with Demeter and her cult are mostly found at Bitchvinta necropolis while in East Georgia they are present at the necropolises of Urbnisi, Zhinvali, Kushanaant gora II (Magraneti), Samtavro. They are also encountered in the glyptic materials obtained by F. Baiern on the Samtavro territor
Labour productivity change: drivers, business impact and macroeconomic moderators
No full textThis paper focuses on the operational drivers of labour productivity changes. We consider two sets of
drivers: a) current working practices b) changes in working practices through management programs.
The relationship between these two sets of drivers and productivity changes are analysed. We also
investigate the importance of productivity growth by looking at the impact of labour productivity
changes on business performance changes. Finally, the moderating effects of industry and country on
the use of drivers of productivity changes are examined. Data from an international survey, IMSS-IV,
are used for the analysis
ELF magnetospheric lines observed by DEMETER
No full textInternational audienceThe influence of man-made activity on the ionosphere may be very important. The effects induced by the Power Line Harmonic Radiation (PLHR) may change the natural wave activity and/or the ionospheric plasma components. One goal of the ionospheric satellite DEMETER launched in June 2004 is to study the ionospheric perturbations which could be related to this anthropogenic activity. As the first step, the paper presents Tram Lines (TL) which have been observed on board DEMETER with frequency intervals close to 50 Hz or 16 Hz 2/3 (the current frequency of the railways). When it is observable the frequency drift of these TL is very slow. It is shown that these events occur during periods of strong or moderate magnetic activity. A wave propagation analysis indicates that the TL observed below the low cutoff frequency of the hiss which is simultaneously present are coming from a region below the satellite. The conclusion is that these TL observed by DEMETER are produced by PLHR or radiation of railways lines
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