40 research outputs found

    On the Lagrangian Dynamics of Atmospheric Zonal Jets and the Permeability of the Stratospheric Polar Vortex

    Get PDF
    The Lagrangian dynamics of zonal jets in the atmosphere are considered, with particular attention paid to explaining why, under commonly encountered conditions, zonal jets serve as barriers to meridional transport. The velocity field is assumed to be two-dimensional and incompressible, and composed of a steady zonal flow with an isolated maximum (a zonal jet) on which two or more travelling Rossby waves are superimposed. The associated Lagrangian motion is studied with the aid of KAM (Kolmogorov--Arnold--Moser) theory, including nontrivial extensions of well-known results. These extensions include applicability of the theory when the usual statements of nondegeneracy are violated, and applicability of the theory to multiply periodic systems, including the absence of Arnold diffusion in such systems. These results, together with numerical simulations based on a model system, provide an explanation of the mechanism by which zonal jets serve as barriers to meridional transport of passive tracers under commonly encountered conditions. Causes for the breakdown of such a barrier are discussed. It is argued that a barrier of this type accounts for the sharp boundary of the Antarctic ozone hole at the perimeter of the stratospheric polar vortex in the austral spring.Comment: Submitted to Journal of the Atmospheric Science

    A model of multiple zonal jets in the oceans : dynamical and kinematical analysis

    Get PDF
    Author Posting. © American Meteorological Society, 2009. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 39 (2009): 2711-2734, doi:10.1175/2009JPO4093.1.Multiple alternating zonal jets observed in the ocean are studied with an idealized quasigeostrophic zonal-channel model, with the supercritical, zonal background flow imposed. Both eastward and westward background flows with vertical shear are considered. The underlying nonlinear dynamics is illuminated with analysis of the vertical-mode interactions and time-mean eddy fluxes. Interactions between the vertical modes are systematically studied. The barotropic component of the jets is maintained by both barotropic–barotropic and baroclinic–baroclinic time-mean interactions; thus, the barotropic component of the jets cannot be accurately simulated with a randomly forced barotropic model. The roles of the vertical-mode interactions in driving the baroclinic component of the jets are also characterized. Not only the first but also the second baroclinic mode is found to be important for maintaining the baroclinic component of the jets, whereas the barotropic component of the jets is maintained mostly by the barotropic and first baroclinic modes. The properties of the eddy forcing were systematically studied. It is shown that the baroclinic component of the jets is maintained by Reynolds stress forcing and resisted by form stress forcing only in the eastward background flow. In the westward background flow, the jets are maintained by form stress forcing and resisted by Reynolds stress forcing. The meridional scaling and kinematical properties of the jets are studied as well as the roles of meridional boundaries. The Rhines scaling for meridional spacing of the jets is not generally confirmed, and it is also shown that there are multiple stable equilibria with different numbers of the time-mean jets. It is also found that the jets are associated with alternating weak barriers to the meridional material transport, but the locations of these barriers are not unique and depend on the direction of the background flow and depth. Finally, if the channel is closed with meridional walls, then the jets become more latent but the eddy forcing properties do not change qualitatively.Funding for PB was provided by NSF Grants OCE 0344094 and OCE 0725796 and by the research grant from the Newton Trust of the University of Cambridge. Funding for IK was provided by NSF Grants OCE 0346178 and 0749722. Funding for JP was provided by NSF Grant OCE 0451086

    Manual de produção de uvas viníferas de alta qualidade.

    Get PDF
    bitstream/item/129038/1/MANUAL-de-PRODUCAO-de-UVAS-VINIFERAS-de-ALTA-QUALIDADE-2015-Revisado-em-31-08-15.pd

    Association of kidney disease measures with risk of renal function worsening in patients with type 1 diabetes

    Get PDF
    Background: Albuminuria has been classically considered a marker of kidney damage progression in diabetic patients and it is routinely assessed to monitor kidney function. However, the role of a mild GFR reduction on the development of stage 653 CKD has been less explored in type 1 diabetes mellitus (T1DM) patients. Aim of the present study was to evaluate the prognostic role of kidney disease measures, namely albuminuria and reduced GFR, on the development of stage 653 CKD in a large cohort of patients affected by T1DM. Methods: A total of 4284 patients affected by T1DM followed-up at 76 diabetes centers participating to the Italian Association of Clinical Diabetologists (Associazione Medici Diabetologi, AMD) initiative constitutes the study population. Urinary albumin excretion (ACR) and estimated GFR (eGFR) were retrieved and analyzed. The incidence of stage 653 CKD (eGFR < 60 mL/min/1.73 m2) or eGFR reduction > 30% from baseline was evaluated. Results: The mean estimated GFR was 98 \ub1 17 mL/min/1.73m2 and the proportion of patients with albuminuria was 15.3% (n = 654) at baseline. About 8% (n = 337) of patients developed one of the two renal endpoints during the 4-year follow-up period. Age, albuminuria (micro or macro) and baseline eGFR < 90 ml/min/m2 were independent risk factors for stage 653 CKD and renal function worsening. When compared to patients with eGFR > 90 ml/min/1.73m2 and normoalbuminuria, those with albuminuria at baseline had a 1.69 greater risk of reaching stage 3 CKD, while patients with mild eGFR reduction (i.e. eGFR between 90 and 60 mL/min/1.73 m2) show a 3.81 greater risk that rose to 8.24 for those patients with albuminuria and mild eGFR reduction at baseline. Conclusions: Albuminuria and eGFR reduction represent independent risk factors for incident stage 653 CKD in T1DM patients. The simultaneous occurrence of reduced eGFR and albuminuria have a synergistic effect on renal function worsening

    Cardiovascular risk rate in hypertensive patients attended in primary health care units: the influence of pharmaceutical care

    Get PDF
    Cardiovascular complications are relevant due to their frequency and severity on the hypertension scenario. Studies refer Pharmaceutical Care (PC) as capable of decreasing cardiovascular risk rate (%CVR) on hypertensive patients. This study aimed to investigate, through a randomized clinical assay, the influence of PC service on the %CVR of hypertensive patients assisted in a health primary care unit from Fortaleza-Ceará. Two study groups were formed: i. Intervention Group (IG), which received orientation about taking medicines, actions aiming to prevent/solve medicine interactions and adverse effects and non-pharmacological interventions for 9 months and, ii. Control Group (CG), which received traditional assistance of the unit and was monitored during the same period. It was observed a statistically significant reduction on %CVR (10.76 to 7.86; p=0.04) and systolic blood pressure levels (SBP) (137.69 to 131.54; p<0.01) in the IG, while, in the CG, there was no significant alteration. 151 Drug Related Problem (DRP) were identified and it was realized 124 pharmaceutical interventions, with 89.2% of them resulting on solution/prevention of the problem. Our findings indicated that the inclusion of the PC service in the hypertensive health assistance was more effective at the %CVR and the SBP reduction in comparison to the traditional assistance offered

    Influência de épocas de desfolha e de colheita na composição físico-química do Vinho Chardonay.

    Get PDF
    O trabalho foi conduzido em Santana do Livramento, no ciclo vegetativo de 1990/91,com o objetivo de avaliar o efeito de épocas de desfolha e de colheita sobre a composição físico-química do vinho Chardonnay. O vinhedo era conduzido em espaldeiro. com espaçamento de 3,5 m entre fileiras e 2,0m entre plantas. As plantas tinham doze anos de idade, foram enxertadas sobre o porta-enxerto S04 e podadas no sistema de cordão esporonado. O delineamento experimental utilizado foi o completamente casualizado, num fatorial incompleto, totalizando onze tratamentos, aplicados em função de quatro épocas de desfolha e três épocas de colheita, levando-se em conta uma data ideal de colheita (DIC);houve três repetições
    corecore