Surface dispersion of coastal discharges in North America towards the Great Pacific Garbage Patch.

This research addresses the surface dispersion of coastal discharges in North America that end up at the Great Pacific Garbage Patch. The evolution of the discharged concentration is calculated through statistical simulations using transition matrices and dispersion ellipses, both based on historical records of surface drifter trajectories. The discharge points are adjacent to urban areas distributed along the coast. The preferential routes, times of arrival, and relative contributions of each site to the accumulation area are quantified. A new statistical delimitation of the position, area and orientation of the garbage patch is proposed. Additional experiments suggest that the tracer retention during the summer is influenced by the low-level atmospheric anticyclone in the Northeastern Pacific, which enhances the Ekman drift and hence favours debris convergence. This effect is reduced when the anticyclone weakens in winter, thus decreasing the debris retention and promoting its westward dispersal by the trade winds.

Magnetic hydrogel particles improve nanopore sequencing of SARS-CoV-2 and other respiratory viruses.

Presented here is a magnetic hydrogel particle enabled workflow for capturing and concentrating SARS-CoV-2 from diagnostic remnant swab samples that significantly improves sequencing results using the Oxford Nanopore Technologies MinION sequencing platform. Our approach utilizes a novel affinity-based magnetic hydrogel particle, circumventing low input sample volumes and allowing for both rapid manual and automated high throughput workflows that are compatible with Nanopore sequencing. This approach enhances standard RNA extraction protocols, providing up to 40 × improvements in viral mapped reads, and improves sequencing coverage by 20-80% from lower titer diagnostic remnant samples. Furthermore, we demonstrate that this approach works for contrived influenza virus and respiratory syncytial virus samples, suggesting that it can be used to identify and improve sequencing results of multiple viruses in VTM samples. These methods can be performed manually or on a KingFisher automation platform.

The effects of abrupt topography on plankton dynamics.

Plankton population dynamics in the upper layer of the ocean depends on upwelling processes that bring nutrients from deeper waters. In turn, these depend on the structure of the vertical velocity field. In coastal areas and in oceanic regions characterized by the presence of strong submarine topographic features, the variable bottom topography induces significant effects on vertical velocities and upwelling/downwelling patterns. As a consequence, large plankton and fish abundances are frequently observed above seamounts, canyons and steep continental shelves. In this work, the dynamics of an NPZ (nutrient-phytoplankton-zooplankton) system is numerically studied by coupling the ecosystem model with a quasi two-dimensional (2D) fluid model with topography. At variance with classical 2D approaches, this formulation allows for an explicit expression of the vertical motions produced when fluid columns are squeezed and stretched as they experience changes of depth. Thus, input or output of nutrients at the surface are associated with fluid motion over the bottom topography. We examine the dynamics of a cyclonic vortex over two basic topographies: a steep escarpment and a submarine mountain. We show that plankton abundance over the escarpment is modulated by the passing of topographic Rossby waves, generated by the vortex-topography interaction. In such configuration, advection effects driven by the flow over the escarpment are of limited relevance for the dynamics of biological fields. By contrast, we find that the flow resulting from the interaction of a vortex with a seamount is sufficiently strong and persistent to allow for a remarkable increase of nutrients, and a corresponding enhancement of phytoplankton and zooplankton concentrations. Over the seamount, advection effects associated with trapped flow perturbations around the summit play an essential role.

Yellow fever outbreak, Imatong, southern Sudan.

In May 2003, the World Health Organization received reports about a possible outbreak of a hemorrhagic disease of unknown cause in the Imatong Mountains of southern Sudan. Laboratory investigations were conducted on 28 serum samples collected from patients in the Imatong region. Serum samples from 13 patients were positive for immunoglobulin M antibody to flavivirus, and serum samples from 5 patients were positive by reverse transcription-polymerase chain reaction with both the genus Flavivirus-reactive primers and yellow fever virus-specific primers. Nucleotide sequencing of the amplicons obtained with the genus Flavivirus oligonucleotide primers confirmed yellow fever virus as the etiologic agent. Isolation attempts in newborn mice and Vero cells from the samples yielded virus isolates from five patients. Rapid and accurate laboratory diagnosis enabled an interagency emergency task force to initiate a targeted vaccination campaign to control the outbreak.

Long-lasting inhibitory avoidance acquisition in rats submitted to the elevated T-maze model of anxiety.

The present study was outlined in order to provide additional behavioral validation to the elevated T-maze as a model of anxiety and memory. In this model, rats acquire an inhibitory avoidance response after successive exposures, and memory can be estimated by retesting later. Two experiments were carried out with rats initially tested at the ages of 30, 60, 90 and 120 days. Experiment 1 showed that, while 100% of subjects studied learned inhibitory avoidance, regardless of their ages, 60-day-old rats needed a higher number of trials in order to reach the criterion to stay 300 s inside the enclosed arm. Experiment 2 explored the relevancy of the aversive stimulus in maintaining the learned experience by retesting the subjects monthly. The results showed that after acquisition of inhibitory avoidance there is remarkable long-lasting memory retrieval. Risk assessment behavior, increasing in the first trial of the retest day, revealed also the approach-avoidance conflict while on the enclosed arm. The results are discussed in terms of age effects and the implications of an enduring learned emotional response in animal models of anxiety and memory.