88 research outputs found
An integrated open-coastal biogeochemistry, ecosystem and biodiversity observatory of the eastern Mediterranean – the Cretan Sea component of the POSEIDON system
There is a general scarcity of oceanic observations that
concurrently examine air–sea interactions, coastal–open-ocean processes and
physical–biogeochemical processes, in appropriate spatiotemporal
scales and under continuous, long-term data acquisition schemes. In the
Mediterranean Sea, the resulting knowledge gaps and observing challenges
increase due to its oligotrophic character, especially in the eastern part
of the basin. The oligotrophic open Cretan Sea's biogeochemistry is
considered to be representative of a greater Mediterranean area up to
106 km2, and understanding its features may be useful on even
larger oceanic scales, since the Mediterranean Sea has been considered a
miniature model of the global ocean. The spatiotemporal coverage of biogeochemical (BGC)
observations in the Cretan Sea has progressively increased over the last
decades, especially since the creation of the POSEIDON observing system,
which has adopted a multiplatform, multivariable approach, supporting BGC
data acquisition. The current POSEIDON system's status includes open and
coastal sea fixed platforms, a Ferrybox (FB) system and Bio-Argo autonomous
floats that remotely deliver fluorescence as a proxy of chlorophyll-a
(Chl-a), O2, pH and pCO2 data, as well as BGC-related physical
variables. Since 2010, the list has been further expanded to other BGC
(nutrients, vertical particulate matter fluxes), ecosystem and biodiversity
(from viruses up to zooplankton) variables, thanks to the addition of
sediment traps, frequent research vessel (R/V) visits for seawater–plankton
sampling and an acoustic Doppler current profiler (ADCP) delivering
information on macrozooplankton–micronekton vertical migration (in the
epipelagic to mesopelagic layer). Gliders and drifters are the new (currently under
integration to the existing system) platforms, supporting BGC monitoring.
Land-based facilities, such as data centres, technical support
infrastructure, calibration laboratory and mesocosms, support and give added
value to the observatory. The data gathered from these platforms are used to
improve the quality of the BGC-ecosystem model predictions, which have
recently incorporated atmospheric nutrient deposition processes and
assimilation of satellite Chl-a data. Besides addressing open scientific
questions at regional and international levels, examples of which are
presented, the observatory provides user-oriented services to marine
policy makers and the society, and is a technological test bed for new
and/or cost-efficient BGC sensor technology and marine equipment. It is part
of European and international observing programs, playing a key role in
regional data handling and participating in harmonization and best practices
procedures. Future expansion plans consider the evolving scientific and
society priorities, balanced with sustainable management.</p
The Neurogenesis Actuator and NR2B/NMDA Receptor Antagonist Ro25-6981 Consistently Improves Spatial Memory Retraining Via Brain Region-Specific Gene Expression
NR2B-containing NMDA (NR2B/NMDA) receptors are important in controlling neurogenesis and are involved in generating spatial memory. Ro25-6981 is a selective antagonist at these receptors and actuates neurogenesis and spatial memory. Inter-structural neuroanatomical profiles of gene expression regulating adult neurogenesis and neuroapoptosis require examination in the context of memory retrieval and reversal learning. The aim was to investigate spatial memory retrieval and reversal learning in relation to gene expression-linked neurogenetic processes following blockade of NR2B/NMDA receptors by Ro25-6981. Rats were trained in Morris water maze (MWM) platform location for 5 days. Ro25-6981 was administered (protocol days 6–7) followed by retraining (days 15–18 or 29–32). Platform location was tested (on days 19 or 33) then post-mortem brain tissue sampling (on days 20 or 34). The expression of three genes known to regulate cell proliferation (S100a6), differentiation (Ascl1), and apoptosis (Casp-3) were concomitantly evaluated in the hippocampus, prefrontal cortex, and cerebellum in relation to the MWM performance protocol. Following initial training, Ro25-6981 enhanced visuospatial memory retrieval performance during further retraining (protocol days 29–32) but did not influence visuospatial reversal learning (day 33). Hippocampal Ascl1 and Casp-3 expressions were correspondingly increased and decreased while cerebellar S100a6 and Casp-3 activities were decreased and increased respectively 27 days after Ro25-6981 treatment. Chronological analysis indicated a possible involvement of new mature neurons in the reconfiguration of memory processes. This was attended by behavioral/gene correlations which revealed direct links between spatial memory retrieval enhancement and modified gene activity induced by NR2B/NMDA receptor blockade and upregulation
Diabetic ketoacidosis
Diabetic ketoacidosis (DKA) is the most common acute hyperglycaemic emergency in people with diabetes mellitus. A diagnosis of DKA is confirmed when all of the three criteria are present — ‘D’, either elevated blood glucose levels or a family history of diabetes mellitus; ‘K’, the presence of high urinary or blood ketoacids; and ‘A’, a high anion gap metabolic acidosis. Early diagnosis and management are paramount to improve patient outcomes. The mainstays of treatment include restoration of circulating volume, insulin therapy, electrolyte replacement and treatment of any underlying precipitating event. Without optimal treatment, DKA remains a condition with appreciable, although largely preventable, morbidity and mortality. In this Primer, we discuss the epidemiology, pathogenesis, risk factors and diagnosis of DKA and provide practical recommendations for the management of DKA in adults and children
Molecular-diffusion and Fluorescence Energy-transfer Studies in Thin Surfactant Films
Thin surfactant films have been formed by dip-coating glass slides in a solution of reversed micelles containing titanium isopropoxide. The alkoxide is slowly hydrolyzed in the presence of reversed micelles since hydrolysis competes with hydration of surfactant polar groups. Adhesion of the surfactant on the glass slide is assisted by incompletely hydrolyzed alkoxide through the following possible mechanism: the alkoxide adheres by-Si-O-Ti-bonds and the surfactant follows by hydrophobic attraction to the isopropyl groups. The films are transparent and visually uniform. Three surfactants, forming reversed micelles, have been investigated: one nonionic, Triton X-100; one anionic, AOT; and one cationic, hexadecyldimethylbenzylammonium chloride. The environment provided by the surfactant film has been studied by fluorescence probing. In particular, we have analyzed pyrene excimer formation as well as energy transfer between pyrene, acting as donor, and coumarin-153 or N-n-heptyl-4-(((dimethylamino)phenyl)ethyl)-pyridinium bromide, acting as acceptor. In Triton and hexadecyldimethylbenzylammonium chloride films, pyrene excimer formation is diffusion-controlled while in AOT films excimer largely comes from pyrene aggregation. Pyrene excimer formation capacity decreases in the presence of cosulubilized poly(vinyl methyl ether) chains. Energy transfer data indicate that coumarin-153 is randomly distributed in the films, but N-n-heptyl-4-(((dimethylamino)phenyl)ethenyl)pyridinium bromide is not randomly distributed but shows a tendency to aggregate. Generally speaking, the benzyl-group-bearing surfactants form fluid structures while AOT may provide a restricted low dimensional environment
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