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We identify effective carriers of Sargassum in the Caribbean Sea and describe a mechanism for coastal choking. Revealed from satellite altimetry, the carriers of Sargassum are mesoscale eddies (vortices of 50-km radius or larger) with coherent material (i.e., fluid) boundaries. These are observer-independent—unlike eddy boundaries identified with instantaneously closed streamlines of the altimetric sea-surface height field—and furthermore harbor finite-time attractors for networks of elastically connected finite-size buoyant or "inertial" particles dragged by ocean currents and winds, a mathematical abstraction of Sargassum rafts. The mechanism of coastal inundation, identified using a minimal model of surface-intensified Caribbean Sea eddies, is thermal instability in the presence of bottom topography. [ABSTRACT FROM AUTHOR]

Drifters designed to mimic floating marine debris and small patches of pelagic Sargassum were satellite tracked in four regions across the North Atlantic. Though subjected to the same initial conditions at each site, the tracks of different drifters quickly diverged after deployment. We explain the clustering of drifter types using a recent Maxey‐Riley theory for surface ocean inertial particle dynamics applied on multidata‐based mesoscale ocean currents and winds from reanalysis. Simulated trajectories of objects at the air‐sea interface are significantly improved when represented as inertial (accounting for buoyancy and size), rather than as perfectly Lagrangian (fluid following) particles. Separation distances between simulated and observed trajectories were substantially smaller for debris‐like drifters than for Sargassum‐like drifters, suggesting that additional consideration of its physical properties relative to fluid velocities may be useful. Our findings can be applied to model variability in movements and distribution of diverse objects floating at the ocean surface. Plain Language Summary: Predicting the fate of floating matter requires one to recognize that they respond differently than Lagrangian (i.e., infinitesimally small, neutrally buoyant) particles to the action of surface currents and winds. Indeed, the Maxey‐Riley equation of fluid mechanics—a Newton second‐law‐type ordinary differential equation—shows that even the motion of seemingly small neutrally buoyant particles immersed in a fluid in motion can substantively deviate from that of Lagrangian particles. The Maxey‐Riley equation has been recently extended to account for the combined effects of ocean current and wind drag on finite‐size particles floating at the ocean surface. We show here that the paths of drifters that mimic marine debris and small Sargassum patches cluster according to their inertial characteristics consistent with the Maxey‐Riley theory. Key Points: Custom‐made marine‐debris‐ and Sargassum‐like undrogued surface drifters are observed to cluster according to design typeThe clustering is explained as a result of inertial effects using a novel Maxey‐Riley theoryThe results have implications for maintaining ecosystem health, search‐and‐rescue operations, and marine safety [ABSTRACT FROM AUTHOR]

We present results from an experiment designed to better understand the mechanism by which ocean currents and winds control flotsam drift. The experiment consisted of deploying in the Florida Current and subsequent satellite tracking of specially designed drifting buoys of various sizes, buoyancies, and shapes. We explain the differences in the trajectories described by the special drifters as a result of their inertia, primarily buoyancy, which constrains the ability of the drifters to adapt their velocities to instantaneous changes in the ocean current and wind that define the carrying flow field. Our explanation of the observed behavior follows from the application of a recently proposed Maxey–Riley theory for the motion of finite-sized particles floating on the ocean surface. The nature of the carrying flow and the domain of validity of the theory are clarified, and a closure proposal is made to fully determine its parameters in terms of the carrying fluid system properties and inertial particle characteristics. [ABSTRACT FROM AUTHOR]

An increase in global wind speeds over time is affecting the global uptake of CO2 by the ocean. We determine the impact of changing winds on gas transfer and CO2 uptake by using the recently updated, global high-resolution, cross-calibrated multiplatform wind product (CCMP-V2) and a fixed monthly pCO2 climatology. In particular, we assess global changes in the context of regional wind speed changes that are attributed to large-scale climate reorganizations. The impact of wind on global CO2 gas fluxes as determined by the bulk formula is dependent on several factors, including the functionality of the gas exchange-wind speed relationship and the regional and seasonal differences in the air-water partial pressure of CO2 gradient (Δ pCO2). The latter also controls the direction of the flux. Fluxes out of the ocean are influenced more by changes in the low-to-intermediate wind speed range, while ingassing is impacted more by changes in higher winds because of the regional correlations between wind and Δ pCO2. Gas exchange-wind speed parameterizations with a quadratic and third-order polynomial dependency on wind, each of which meets global constraints, are compared. The changes in air-sea CO2 fluxes resulting from wind speed trends are greatest in the equatorial Pacific and cause a 0.03-0.04 Pg C decade−1 increase in outgassing over the 27 year time span. This leads to a small overall decrease of 0.00 to 0.02 Pg C decade−1 in global net CO2 uptake, contrary to expectations that increasing winds increase net CO2 uptake. [ABSTRACT FROM AUTHOR]

Objective: Diabetes may accelerate atheromatosis in uremic patients. Our aim was to assess the influence of type 1 diabetes on the atheromatosis-related inflammation in patients with chronic kidney disease (CKD).Research Design and Methods: We analyzed the expression of proinflammatory cytokines and adhesion molecules in the inferior epigastric artery walls of type 1 diabetic patients with CKD (n = 22) and compared it with nondiabetic uremic patients (n = 92) at the time of kidney transplantation. We evaluated the expression of interleukin (IL)-6, monocyte chemotractant protein (MCP)-1, vascular cell adhesion molecule (VCAM)-1, intercellular adhesion molecule-1, and the activation of nuclear factor-κβ p65 (NFkB-p65). Common carotid intima-media thickness (c-IMT) was determined by conventional echography.Results: IL-6, MCP-1, and VCAM-1 proteins were elevated in type 1 diabetic patients compared with nondiabetic subjects (P < 0.05). The nuclear localization of NFkB-p65 was higher in type 1 diabetic patients (P < 0.01) and correlated with the levels of MCP-1 in this group (r = 0.726, P < 0.001). Arterial fibrosis correlated with IL-6 and MCP-1 levels (r = 0.411, P < 0.001 and r = 0.378, P = 0.001). A significant correlation was observed between VCAM-1 levels and both the degree of arterial narrowing and c-IMT.Conclusions: Type 1 diabetes produces a proinflammatory state in the arteries of end-stage CKD patients, with increased levels of IL-6, MCP-1, and VCAM-1, as well as a greater degree of p65 activation, which are associated with more severe vascular lesions and higher c-IMT. Although causality is not demonstrated, these findings support the major role of inflammation in type 1 diabetic patients with CKD. [ABSTRACT FROM AUTHOR]