437 research outputs found

    Dyadic weights on RnR^n and reverse Holder inequalities

    Get PDF
    We prove that for any weight ϕ\phi defined on [0,1]n[0,1]^n that satisfies a reverse Holder inequality with exponent p > 1 and constant c≄1c\ge1 upon all dyadic subcubes of [0,1]n[0,1]^n, it's non increasing rearrangement satisfies a reverse Holder inequality with the same exponent and constant not more than 2nc−2n+12^nc-2^n + 1, upon all subintervals of [0;1][0; 1] of the form [0;t][0; t]. This gives as a consequence, according to the results in [8], an interval [p;p0(p;c))=Ip,c[p; p_0(p; c)) = I{p,c}, such that for any q∈Ip,cq \in I{p,c}, we have that ϕ\phi is in LqL^q.Comment: 10 page

    Local lower norm estimates for dyadic maximal operators and related Bellman functions

    Get PDF
    We provide lower LqL^q and weak LpL^p-bounds for the localized dyadic maximal operator on RnR^n, when the local L1L^1 and the local LpL^p norm of the function are given. We actually do that in the more general context of homo- geneous tree-like families in probability spaces.Comment: 9 page

    Estimates for Bellman functions related to dyadic-like maximal operators on weighted spaces

    Get PDF
    We provide some new estimates for Bellman type functions for the dyadic maximal opeator on RnR^n and of maximal operators on martingales related to weighted spaces. Using a type of symmetrization principle, introduced for the dyadic maximal operator in earlier works of the authors we introduce certain conditions on the weight that imply estimate for the maximal operator on the corresponding weighted space. Also using a well known estimate for the maximal operator by a double maximal operators on different m easures related to the weight we give new estimates for the above Bellman type functions.Comment: 10 pages. arXiv admin note: text overlap with arXiv:1511.0611

    On weak type inequalities for dyadic maximal functions

    Get PDF
    AbstractWe obtain sharp estimates for the localized distribution function of the dyadic maximal function Mϕd, given the local L1 norms of ϕ and of G○ϕ where G is a convex increasing function such that G(x)/x→+∞ as x→+∞. Using this we obtain sharp refined weak type estimates for the dyadic maximal operator

    Evolution of perturbations in 3D air quality models

    Get PDF
    The deterministic approach of sensitivity analysis is applied on the solution vector of an Air Quality Model. In particular, the photochemical CAMx code is augmented with derivatives utilising the automatic differentiation software ADIFOR. The enhanced with derivatives version of the model is then adopted in a study of the effect of perturbations at the boundary conditions on the predicted ozone concentrations. The calculated derivative matrix provides valuable information e.g., on the ordering of the infl uential factors or the localisation of highly affected regions. Two fundamentally different domains of the Auto-Oil II programme were used as test cases for the simulations, namely Athens and Milan. The results suggest that ozone concentration be highly affected by its own boundary conditions and subsequently, with an order of magnitude less, by the boundary conditions of NOX and VOC

    An Integrated Decision-Support Information System on the Impact of Extreme Natural Hazards on Critical Infrastructure

    Get PDF
    In this paper, we introduce an Integrated Decision-Support Tool (IDST v2.0) which was developed as part of the INFRARISK project (https://www.infrarisk-fp7.eu/). The IDST is an online tool which demonstrates the implementation of a risk-based stress testing methodology for analyzing the potential impact of natural hazards on transport infrastructure networks. The IDST is enabled with a set of software workflow processes that allow the definition of multiple cascading natural hazards, geospatial coverage and impact on important large infrastructure, including those which are critical to transport networks in Europe. Stress tests on these infrastructure are consequently performed together with the automated generation of useful case study reports for practitioners. An exemplar stress test study using the IDST is provided in this paper. In this study, risks and consequences of an earthquake-triggered landslide scenario in Northern Italy is described. Further, it provides a step-by-step account of the developed stress testing overarching methodology which is applied to the impact on a road network of the region of interest

    Intracisternal delivery of NFÎșB-inducible scAAV2/9 reveals locoregional neuroinflammation induced by systemic kainic acid treatment.

    Get PDF
    We have previously demonstrated disease-dependent gene delivery in the brain using an AAV vector responding to NFÎșB activation as a probe for inflammatory responses. This vector, injected focally in the parenchyma prior to a systemic kainic acid (KA) injection mediated inducible transgene expression in the hippocampus but not in the cerebellum, regions, respectively, known to be affected or not by the pathology. However, such a focal approach relies on previous knowledge of the model parameters and does not allow to predict the whole brain response to the disease. Global brain gene delivery would allow to predict the regional distribution of the pathology as well as to deliver therapeutic factors in all affected brain regions. We show that self-complementary AAV2/9 (scAAV2/9) delivery in the adult rat cisterna magna allows a widespread but not homogenous transduction of the brain. Indeed, superficial regions, i.e., cortex, hippocampus, and cerebellum were more efficiently transduced than deeper regions, such as striatum, and substantia nigra. These data suggest that viral particles penetration from the cerebrospinal fluid (CSF) into the brain is a limiting factor. Interestingly, AAV2/9-2YF a rationally designed capsid mutant (affecting surface tyrosines) increased gene transfer efficiency approximately fivefold. Neurons, astrocytes, and oligodendrocytes, but not microglia, were transduced in varying proportions depending on the brain region and the type of capsid. Finally, after a single intracisternal injection of scAAV2/9-2YF using the NFÎșB-inducible promoter, KA treatment induced transgene expression in the hippocampus and cortex but not in the cerebellum, corresponding to the expression of the CD11b marker of microglial activation. These data support the use of disease-inducible vectors administered in the cisterna magna as a tool to characterize the brain pathology in systemic drug-induced or transgenic disease models. However, further improvements are required to enhance viral particles penetration into the brain

    An Assessment of the Efficiency of Dust Regional Modelling to Predict Saharan Dust Transport Episodes

    Get PDF
    Aerosol levels at Mediterranean Basin are significantly affected by desert dust that is eroded in North Africa and is transported northwards. This study aims to assess the performance of the Dust REgional Atmospheric Model (BSC-DREAM8b) in the prediction of dust outbreaks near the surface in Eastern Mediterranean. For this purpose, model PM10 predictions covering a 7-year period and PM10 observations at five surface monitoring sites in Greece are used. A quantitative criterion is set to select the significant dust outbreaks defined as those when the predicted PM10 surface concentration exceeds 12 Όg/m3. The analysis reveals that significant dust transport is usually observed for 1–3 consecutive days. Dust outbreak seasons are spring and summer, while some events are also forecasted in autumn. The seasonal variability of dust transport events is different at Finokalia, where the majority of events are observed in spring and winter. Dust contributes by 19–25% to the near surface observed PM10 levels, which can be increased to more than 50 Όg/m3 during dust outbreaks, inducing violations of the air quality standards. Dust regional modeling can be regarded as a useful tool for air quality managers when assessing compliance with air quality limit values

    The impact of temperature changes on summer time ozone and its precursors in the Eastern Mediterranean

    Get PDF
    Changes in temperature due to variability in meteorology and climate change are expected to significantly impact atmospheric composition. The Mediterranean is a climate sensitive region and includes megacities like Istanbul and large urban agglomerations such as Athens. The effect of temperature changes on gaseous air pollutant levels and the atmospheric processes that are controlling them in the Eastern Mediterranean are here investigated. The WRF/CMAQ mesoscale modeling system is used, coupled with the MEGAN model for the processing of biogenic volatile organic compound emissions. A set of temperature perturbations (spanning from 1 to 5 K) is applied on a base case simulation corresponding to July 2004. The results indicate that the Eastern Mediterranean basin acts as a reservoir of pollutants and their precursor emissions from large urban agglomerations. During summer, chemistry is a major sink at these urban areas near the surface, and a minor contributor at downwind areas. On average, the atmospheric processes are more effective within the first 1000 m above ground. Temperature increases lead to increases in biogenic emissions by 9±3% K<sup>−1</sup>. Ozone mixing ratios increase almost linearly with the increases in ambient temperatures by 1±0.1 ppb O<sub>3</sub> K<sup>−1</sup> for all studied urban and receptor stations except for Istanbul, where a 0.4±0.1 ppb O<sub>3</sub> K<sup>−1</sup> increase is calculated, which is about half of the domain-averaged increase of 0.9±0.1 ppb O<sub>3</sub> K<sup>−1</sup>. The computed changes in atmospheric processes are also linearly related with temperature changes
    • 

    corecore