177 research outputs found

    A note on intermittency for the fractional heat equation

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    The goal of the present note is to study intermittency properties for the solution to the fractional heat equation \frac{\partial u}{\partial t}(t,x) = -(-\Delta)^{\beta/2} u(t,x) + u(t,x)\dot{W}(t,x), \quad t>0,x \in \bR^d with initial condition bounded above and below, where β∈(0,2]\beta \in (0,2] and the noise WW behaves in time like a fractional Brownian motion of index H>1/2H>1/2, and has a spatial covariance given by the Riesz kernel of index α∈(0,d)\alpha \in (0,d). As a by-product, we obtain that the necessary and sufficient condition for the existence of the solution is α<β\alpha<\beta.Comment: 12 page

    Sustainable for Whom? Green Urban Development, Environmental Gentrification, and the Atlanta Beltline

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    Large-scale, sustainable urban development projects can transform surrounding neighborhoods. Without precautionary policies, environmental amenities produced by these projects, such as parks, trails, walkability, and higher-density development, tend to result in higher land and housing costs. This will make it harder for a low- and moderate-income households to live near the projects, and neighborhoods are likely to become increasingly affluent. The Atlanta Beltline will ultimately connect 45 Atlanta neighborhoods via a 22-mile loop of trails, parks, and eventually a streetcar, all of which follow abandoned railroad tracks. This paper examines the effect of the Beltline on housing values within one half mile. From 2011 to 2015, depending on the segment of the Beltline, values rose between 17.9 percent and 26.6 percent more for homes within a half-mile of the Beltline than elsewhere. The implications for housing affordability and neighborhood change of projects like the Beltline, and associated policy questions, are addressed

    Ozone therapy – a rare and avoidable source of infectious pathology of the spine

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    Ozone therapy is considered by many as an effective therapy for spinal degenerative pathologies. Despite its possible favorable results, we present a series of serious infectious complications, clearly related to ozone therapy and their treatment. The authors discuss their results compared with the literature and advocate for prudence when recommending ozone therapy

    Comparison of 10-year overall survival between patients with G1 and G2 grade Ta bladder tumors

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    To compare long-term overall survival (OS) in patients with G1 and G2 grade Ta bladder cancer after transurethral resection of bladder tumors (TURBTs). Secondary aim was to investigate clinical and pathologic prognostic factors for OS of Ta patients, except G3/high grade (HG). A total of 243 patients, retrospectively selected, with Ta nonmuscle invasive bladder cancer (NMIBC) underwent TURBT between January 2006 and December 2008 (median follow-up 109 months). Inclusion criteria were: Ta at first manifestation, G1 or G2 grade with no associated carcinoma in situ (CIS). Seventy-nine patients were excluded due to concomitant CIS (1), G3/HG tumors (47), and lost to follow-up (31). Ethical approval was obtained from the Ethical Committee of the Mures County Hospital. Statistical analysis was performed using STATA 11.0. Following inclusion criteria, 164 patients with primary G1 or G2 Ta tumors, were enrolled. Recurrence was observed in 26 (15.8%) and progression in 5 (3%) patients. Ten-year survival in G1 patients was 67.8% (CI 54.3-78.1) and in G2 patients 59% (CI 49-67.3) (P=.31). Univariable and multivariable logistic regression analysis underlined that advanced age at diagnosis (hazard ratio [HR] 1.10) and no Bacillus Calmette-Guerin (BCG) treatment (HR 0.24 and 0.29) were independent predictors for death at 10 years after diagnosis. Long-term analysis confirms that patients with well differentiated (G1) and moderately well differentiated (G2) Ta tumors have similar OS. A longer OS was even reported in those who underwent BCG adjuvant therapy

    Effect of cryogenic grinding on fatigue life of additively manufactured maraging steel

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    Additive manufacturing (AM) is replacing conventional manufacturing techniques due to its ability to manufacture complex structures with near-net shape and reduced material wastage. However, the poor surface integrity of the AM parts deteriorates the service life of the components. The AM parts should be subjected to post-processing treatment for improving surface integrity and fatigue life. In this research, maraging steel is printed using direct metal laser sintering (DMLS) process and the influence of grinding on the fatigue life of this additively manufactured material was investigated. For this purpose, the grinding experiments were performed under two different grinding environments such as dry and cryogenic conditions using a cubic boron nitride (CBN) grinding wheel. The results revealed that surface roughness could be reduced by about 87% under cryogenic condition over dry grinding. The fatigue tests carried out on the additive manufactured materials exposed a substantial increase of about 170% in their fatigue life when subjected to cryogenic grinding

    Inter-Comparison of the Spatial Distribution of Methane in the Water Column From Seafloor Emissions at Two Sites in the Western Black Sea Using a Multi-Technique Approach

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    Understanding the dynamics and fate of methane (CH 4 ) release from oceanic seepages on margins and shelves into the water column, and quantifying the budget of its total discharge at different spatial and temporal scales, currently represents a major scientific undertaking. Previous works on the fate of methane escaping from the seafloor underlined the challenge in both, estimating its concentration distribution and identifying gradients. In April 2019, the Envri Methane Cruise has been conducted onboard the R/V Mare Nigrum in the Western Black Sea to investigate two shallow methane seep sites at ∼120 m and ∼55 m water depth. Dissolved CH 4 measurements were conducted with two continuous in-situ sensors: a membrane inlet laser spectrometer (MILS) and a commercial methane sensor (METS) from Franatech GmbH. Additionally, discrete water samples were collected from CTD-Rosette deployment and standard laboratory methane analysis was performed by gas chromatography coupled with either purge-and-trap or headspace techniques. The resulting vertical profiles (from both in situ and discrete water sample measurements) of dissolved methane concentration follow an expected exponential dissolution function at both sites. At the deeper site, high dissolved methane concentrations are detected up to ∼45 m from the seabed, while at the sea surface dissolved methane was in equilibrium with the atmospheric concentration. At the shallower site, sea surface CH 4 concentrations were four times higher than the expected equilibrium value. Our results seem to support that methane may be transferred from the sea to the atmosphere, depending on local water depths. In accordance with previous studies, the shallower the water, the more likely is a sea-to-atmosphere transport of methane. High spatial resolution surface data also support this hypothesis. Well localized methane enriched waters were found near the surface at both sites, but their locations appear to be decoupled with the ones of the seafloor seepages. This highlights the need of better understanding the processes responsible for the transport and transformation of the dissolved methane in the water column, especially in stratified water masses like in the Black Sea
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