A numerical model of instabilities in the Florida Current

An isopycnic coordinate numerical model is configured as an infinitely long channel with the width and bottom topography of the Straits of Florida at 27N to investigate the possibility that Florida Current meanders are due to dynamical instabilities. One mass/flow configuration with which to initialize the model is developed primarily from theoretical considerations, a second from the analysis of ST ACS observations (Leaman et al., 1987). To ascertain the effect of the bottom topography, flat bottom experiments are first examined. The current is found to be baroclinically unstable in the classical sense (Eady, 1949) to perturbations with wavelengths greater than ∼85 km, and the meanders which develop eventually dominate the channel flow pattern. When the 27N topography is included, the instability is greatly reduced, but the primary source of perturbation energy remains the baroclinic one. The meanders thus produced have wavelengths, periods, and amplitudes similar to those documented in the literature (Schmitz and Richardson, 1968; Lee and Mayer, 1977; Johns and Schott, 1987). The results are briefly compared with De Szoeke\u27s (1975) application of his theory of modified Eady and hybrid instabilities to the Straits of Florida. From an energetics standpoint the instabilities in the model appear to be similar to the latter. From the point of view of wavelength, period and e-folding time of the most rapidly growing wave, however, they most resemble the topographically modified Eady instabilities

Solution to the problem of tomographic scanning of objects by small area X-Ray detectors

Standard X-Ray tomographic setups basically consist of 3 parts: radiation source, mechanics for mounting a sample and detector system. Each part of tomographic setup in one way or another contributes into the quality of reconstructed images. Detector system is responsible for data acquisition process. Development of detectors improves them in terms of resolution, acquisition speed, dark current etc. Such improvements increases costs for producing of detectors as well as their final price. Tomographic scanning of long objects requires using detectors of corresponding size. It makes tomographic setups expensive, because the price of detectors also increases with increasing of their size. Presented work proposes to solve this problem by shifting detector along the longest dimension of the sample and applying optimized filtered backprojection algorithm

Pop-up cavities

Метою роботи є дослідження маловивченого на теперішній час процесу переміщення збережених у приповерхневому вуглепородному масиві Донбасу пустот від місця їхнього первинного розташування до земної поверхні.The object of this paper is research into the understudied for now process of cavities, preserved in the sub-surface coal-bearing strata in the Donets Basin, moving from the places of their original location towards the surface.Целью работы является исследование малоизученного в настоящее время процесса перемещения сохранившихся в приповерхностном углепородном массиве Донбасса пустот от мест их первоначального расположения к земной поверхности. Методика исследования. Проанализированы фактические случаи так называемого всплывания пустот в угледобывающей практике. Выполнен абстрактный расчёт поэтапного всплывания условно сохранившейся выработки (пустоты) в породном массиве различной прочности

Worms:Pernicious parasites or allies against allergies?

Host-parasite interactio

Інженерна комп’ютерна графіка

Розглянуто відомості про систему тривимірного моделювання КОМПАС-3D при виконанні практичних завдань, побудову тривимірних моделей деталей і складальних одиниць машин та обладнання, будівельних споруд, а також про випуск асоціативних креслеників, розробку специфікацій, експлікацій, інших текстових документів

NO2 inhalation induces maturation of pulmonary CD11c+ cells that promote antigenspecific CD4+ T cell polarization

<p>Abstract</p> <p>Background</p> <p>Nitrogen dioxide (NO₂) is an air pollutant associated with poor respiratory health, asthma exacerbation, and an increased likelihood of inhalational allergies. NO₂is also produced endogenously in the lung during acute inflammatory responses. NO₂can function as an adjuvant, allowing for allergic sensitization to an innocuous inhaled antigen and the generation of an antigen-specific Th2 immune response manifesting in an allergic asthma phenotype. As CD11c⁺antigen presenting cells are considered critical for naïve T cell activation, we investigated the role of CD11c⁺cells in NO₂-promoted allergic sensitization.</p> <p>Methods</p> <p>We systemically depleted CD11c⁺cells from transgenic mice expressing a simian diphtheria toxin (DT) receptor under of control of the CD11c promoter by administration of DT. Mice were then exposed to 15 ppm NO₂followed by aerosolized ovalbumin to promote allergic sensitization to ovalbumin and were studied after subsequent inhaled ovalbumin challenges for manifestation of allergic airway disease. In addition, pulmonary CD11c⁺cells from wildtype mice were studied after exposure to NO₂and ovalbumin for cellular phenotype by flow cytometry and <it>in vitro </it>cytokine production.</p> <p>Results</p> <p>Transient depletion of CD11c⁺cells during sensitization attenuated airway eosinophilia during allergen challenge and reduced Th2 and Th17 cytokine production. Lung CD11c⁺cells from wildtype mice exhibited a significant increase in MHCII, CD40, and OX40L expression 2 hours following NO₂exposure. By 48 hours, CD11c⁺MHCII⁺DCs within the mediastinal lymph node (MLN) expressed maturation markers, including CD80, CD86, and OX40L. CD11c⁺CD11b^-and CD11c⁺CD11b⁺pulmonary cells exposed to NO₂<it>in vivo </it>increased uptake of antigen 2 hours post exposure, with increased ova-Alexa 647⁺CD11c⁺MHCII⁺DCs present in MLN from NO₂-exposed mice by 48 hours. Co-cultures of ova-specific CD4⁺T cells from naïve mice and CD11c⁺pulmonary cells from NO₂-exposed mice produced IL-1, IL-12p70, and IL-6 <it>in vitro </it>and augmented antigen-induced IL-5 production.</p> <p>Conclusions</p> <p>CD11c⁺cells are critical for NO₂-promoted allergic sensitization. NO₂exposure causes pulmonary CD11c⁺cells to acquire a phenotype capable of increased antigen uptake, migration to the draining lymph node, expression of MHCII and co-stimulatory molecules required to activate naïve T cells, and secretion of polarizing cytokines to shape a Th2/Th17 response.</p

The role of salinity in the decadal variability of the North Atlantic meridional overturning circulation

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Climate Dynamics 33 (2009): 777-793, doi:10.1007/s00382-008-0523-2.An OGCM hindcast is used to investigate the linkages between North Atlantic Ocean salinity and circulation changes during 1963–2003. The focus is on the eastern subpolar region consisting of the Irminger Sea and the eastern North Atlantic where a careful assessment shows that the simulated interannual to decadal salinity changes in the upper 1500 m reproduce well those derived from the available record of hydrographic measurements. In the model, the variability of the Atlantic meridional overturning circulation (MOC) is primarily driven by changes in deep water formation taking place in the Irminger Sea and, to a lesser extent, the Labrador Sea. Both are strongly influenced by the North Atlantic Oscillation (NAO). The modeled interannual to decadal salinity changes in the subpolar basins are mostly controlled by circulation-driven anomalies of freshwater flux convergence, although surface salinity restoring to climatology and other boundary fluxes each account for approximately 25% of the variance. The NAO plays an important role: a positive NAO phase is associated with increased precipitation, reduced northward salt transport by the wind-driven intergyre gyre, and increased southward flows of freshwater across the Greenland-Scotland ridge. Since the NAO largely controlled deep convection in the subpolar gyre, fresher waters are found near the sinking region during convective events. This markedly differs from the active influence on the MOC that salinity exerts at decadal and longer timescales in most coupled models. The intensification of the MOC that follows a positive NAO phase by about 2 years does not lead to an increase in the northward salt transport into the subpolar domain at low frequencies because it is cancelled by the concomitant intensification of the subpolar gyre which shifts the subpolar front eastward and reduces the northward salt transport by the North Atlantic Current waters. This differs again from most coupled models, where the gyre intensification precedes that of the MOC by several years.Support from NSF Grant 82677800 with the Woods Hole Oceanographic Institution, and (to CF) from the Institut universitaire de France and European FP6 project DYNAMITE (contract 003903-GOCE) and (to JD) from the NOAA Office of Hydrologic Development through a scientific appointment administered by UCAR is gratefully acknowledged

Individualism and stock price crash risk

Employing a sample of 26,473 firms across 42 countries from 1990 to 2013, we find that firms located in countries with higher individualism have higher stock price crash risk. Furthermore, individualism can be transmitted by foreign investors from overseas markets to influence local firms’ crash risk, and can exacerbate the impact of firm risk taking and earnings management on crash risk. Moreover, the positive relation between individualism and crash risk is amplified during the global financial crisis and attenuated by enhanced country-level financial information transparency and the adoption of International Financial Reporting Standards