We study the impact of decadal inversions of the Ionian upper layer circulation (denominated as Adriatic‐Ionian Bimodal Oscillation System) on thermohaline properties of the Levantine and Cretan ...Seas. Lagrangian drifter data and surface geostrophic currents show that the Atlantic Water (AW) flow is well organized and most intense when the Ionian circulation is cyclonic. During the Ionian anticyclonic phase, the AW spreading pathway is the longest, contributing to its prolonged mixing and higher salinity once it reaches the Levantine. Thus, the Levantine basin is subject to less dilution by AW during the anticyclonic surface circulation phase. Empirical orthogonal function analysis of the sea level shows a large‐amplitude circular feature in the northern Ionian which matches the cyclonic/anticyclonic gyre obtained from Lagrangian measurements. Furthermore, it reveals the out‐of‐phase variability of the North Ionian Gyre and the Aegean and Levantine sea levels. We further show that the surface salinity of the Levantine basin variation is out of phase with that of the Ionian surface layers. Salinity variations of the deepwater column in the Aegean are out of phase with the Ionian surface salinity values, owing probably to a fast transfer of the surface salinity changes via winter deep convection. The changing of the Levantine and Cretan Seas' salinity parallel to the Ionian circulation inversions suggests that the preconditioning for the eastern Mediterranean transient (EMT) is driven by internal processes. As the Ionian inversions are cyclical events, we conclude that the EMT is not an isolated episode but potentially a recurrent phenomenon.
Key Points
Inversions of the Ionian surface circulation determine eastward AW propagation
Levantine surface layer salinity depends on the intensity of the Atlantic Water
EMT is a potentially recurrent event driven by internal processes
The accurate knowledge of the ocean's mean dynamic topography (MDT) is a crucial issue for a number of oceanographic applications and, in some areas of the Mediterranean Sea, important limitations ...have been found pointing to the need of an upgrade. We present a new MDT that was computed for the Mediterranean Sea. It profits from improvements made possible by the use of extended data sets and refined processing. The updated data set spans the 1993-2012 period and consists of drifter velocities, altimetry data, hydrological profiles and model data. The methodology is similar to the previous MDT by Rio et al. (2007). However, in Rio et al. (2007) no hydrological profiles had been taken into account. This required the development of dedicated processing. A number of sensitivity studies have been carried out to obtain the most accurate MDT as possible. The main results from these sensitivity studies are the following: moderate impact to the choice of correlation scales but almost negligible sensitivity to the choice of the first guess (model solution). A systematic external validation to independent data has been made to evaluate the performance of the new MDT. Compared to previous versions, SMDT-MED-2014 (Synthetic Mean Dynamic Topography of the MEDiterranean sea) features shorter-scale structures, which results in an altimeter velocity variance closer to the observed velocity variance and, at the same time, gives better Taylor skills.
The most prominent oceanographic features in the Central Mediterranean are decadal reversals of the Northern Ionian Gyre (NIG), interpreted in terms of internal processes. Altimetry data, drifter ...data and model surface salinity products are used in this paper to define some specific features of the circulation related to the anticyclonic or cyclonic NIG modes. Results not only highlight different shapes and intensities of the Mid-Ionian Jet and northern Ionian meander among the two circulation mode, but emphasize distinct behaviour within the same mode, imputable to the variability of the mesoscale quasi-permanent features. The wind-driven Messina Rise Vortex, on the western side of the northern Ionian, and the Pelops Gyre, on the eastern side of the northern Ionian, show different behaviour during the first (1993–1996) and the second (2006–2010) anticyclonic periods, related to the cyclonic activity along the dense water pathway. When the dense water was of Aegean origin (1993–1996; “Aegean” anticyclone), the cyclonic mesoscale activity on the eastern flank of the Ionian overwhelmed the anticyclonic wind forcing, and led to the disappearance of the Pelops Gyre. When the dense water was of Adriatic origin (2006–2010; “Adriatic” anticyclone), the strengthening of cyclonic mesoscale activity on the western flank of the Ionian caused the shape change of the Messina Rise Vortex, favouring its longitudinal extension. The zonally-elongated Messina Rise Vortex reduced the inflow of Atlantic Water in the northern Ionian, and induced a strengthening of the eastward flowing Mid-Ionian Jet in the southern Ionian and Cretan Passage. From these results, it emerges that the interannual variability of the wind-driven quasi-permanent mesoscale gyres in the Ionian is influenced by internal forcing (location of the deep water formation site – Aegean or Adriatic Sea), in turn related to the major local climatic shift occurred in the last decades (the Eastern Mediterranean Transient). We show that the interplay between decadal and interannual variability, or rather between basin-wide and mesoscale circulation, affected the intrinsic characteristics of the NIG reversals.
Zinc oxide (ZnO) thin films were deposited by spray pyrolysis technique using different precursors. Three starting solutions salts namely: zinc acetate, zinc chloride and zinc nitrate were used. The ...properties of these solutions and their influence upon ZnO films growth rate are investigated. The obtained results indicate that the dissociation energy of the starting solution plays an important role on films growth rate. A linear relationship between the solution dissociation energy and the growth rate activation energy was found. However, the surface tension of the used solution controls the droplet shape impact. Both solution surface tension and dissociation enthalpy alter the microstructure of the formed film. Films deposited with zinc acetate are characterized by a smooth surface, dense network and high transparency, while films deposited with zinc chloride have a better crystallinity and low optical transmittance.
► The solution surface tension and dissociation enthalpy of the precursor alter the droplet dynamic. ► A linear relationship between the solution dissociation energy and the growth rate activation energy was found. ► Both precursor surface tension and dissociation enthalpy control film microstructure. ► SEM image reveals that film deposited with zinc chloride is composed with separated hexagonal ZnO columns. ► Films deposited with acetate and nitride precursors have a dense microstructure.
This paper focuses on the study of the Tyrrhenian Sea, a subbasin of the western Mediterranean whose surface and near‐surface dynamics are still relatively poorly known, in particular, its southern ...region. Its circulation is described first by a set of 53 surface drifters deployed in the area between December 2001 and February 2004. In order to supplement the drifter data with continuously and uniformly sampled observations and to characterize the seasonal, as well as higher‐frequency variability of the surface circulation, the Lagrangian analysis was associated to simultaneous satellite remotely sensed altimeter, covering the period 2001–2004. The investigation was based on trajectory analysis and on the computation of the pseudo‐Eulerian statistics using the same binning and space‐time averaging for drifter and altimeter data. The data reveal a complex pattern of the circulation, especially in the southern region of the Tyrrhenian, dominated by semipermanent recirculations and transient features, which sometimes makes it difficult to identify a consistent mean flow, while the northern subbasin is characterized by a pair composed of cyclonic and anticyclonic circulations known in the literature as the North Tyrrhenian Cyclone and North Tyrrhenian Anticyclone. The pseudo‐Eulerian statistics computed with the two data sets evidenced the representativeness of a joint analysis of altimeter and drifter data and yielded useful indications about proper preliminary preprocessing and resampling procedures, so as to make the comparison statistically sound.
Abstract
Zirconium fluoride (ZBLAN) glass, the standard material used in fiber-based mid-infrared photonics, has been re-designed to enable the fabrication of high index-contrast low-loss waveguides ...via femtosecond laser direct writing. We demonstrate that in contrast to pure ZBLAN, a positive index change of close to 10
−2
can be induced in hybrid zirconium/hafnium (Z/HBLAN) glasses during ultrafast laser inscription and show that this can be explained by an electron cloud distortion effect that is driven by the existence of two glass formers with contrasting polarizability. High numerical aperture (NA) type-I waveguides that support a well confined 3.1 μm wavelength mode with a mode-field diameter (MFD) as small as 12 μm have successfully been fabricated. These findings open the door for the fabrication of mid-infrared integrated photonic devices that can readily be pigtailed to existing ZBLAN fibers.
Abstract
STUDY QUESTION
Are in vitro maturation (IVM) rates of cumulus-oocyte complexes (COCs), retrieved from breast cancer patients seeking urgent fertility preservation (FP) before neoadjuvant ...chemotherapy, different between those recovered in the follicular or in the luteal phase of the cycle?
SUMMARY ANSWER
The present investigation reveals no major difference in the number of COCs recovered or their IVM rates whatever the phase of the cycle at which egg retrieval is performed, suggesting that IVM is a promising tool for breast cancer patients seeking urgent oocyte cryopreservation.
WHAT IS KNOWN ALREADY
FP now represents a standard of care for young cancer patients having to undergo gonadotoxic treatment. Mature oocyte cryopreservation after IVM of COCs has been proposed for urgent FP, especially in women, who have no time to undergo ovarian stimulation, or when it is contraindicated.
STUDY DESIGN, SIZE, DURATION
From January 2011 to December 2014, we prospectively studied 248 breast cancer patients awaiting neoadjuvant chemotherapy, aged 18–40 years, candidates for oocyte vitrification following IVM, either at the follicular or the luteal phase of the cycle.
PARTICIPANTS/MATERIALS, SETTING, METHODS
Serum anti-Müllerian hormone and progesterone levels and antral follicle count (AFC) were measured prior to oocyte retrieval. Patients were sorted into two groups according to the phase of the cycle during which eggs were harvested (Follicular phase group, n = 127 and Luteal phase group, n = 121). Number of COCs recovered, maturation rates after 48 h of culture and total number of oocytes cryopreserved were assessed. Moreover, the oocyte retrieval rate (ORR) was calculated by the number of COCs recovered ×100/AFC.
MAIN RESULTS AND THE ROLE OF CHANCE
In the Follicular and the Luteal phase groups, women were comparable in terms of age, BMI and markers of follicular ovarian status. There was no significant difference in the number of COCs recovered (mean ± SEM), 9.3 ± 0.7 versus 11.1 ± 0.8, and ORR (median (range)) 43.1 (1–100) versus 47.8 (7.7–100)%. Moreover, maturation rates after 48 h of culture (median (range)) were comparable in the follicular and luteal phase groups, 66.7 (20–100) versus 64.5 (0–100)%. Finally, the total number of oocytes cryopreserved (mean ± SEM) was similar in both groups (6.2 ± 0.4 versus 6.8 ± 0.5).
LIMITATIONS, REASONS FOR CAUTION
Despite the intact meiotic competence of immature oocytes recovered during the follicular or the luteal phase, there is a dramatic lack of data regarding the outcome of IVM oocytes cryopreserved in cancer patients.
WIDER IMPLICATIONS OF THE FINDINGS
IVM of oocytes may be an interesting method of FP in urgent situations. Improving the culture conditions will be needed to increase the maturation rates and the overall potential of in vitro matured oocytes.
STUDY FUNDING/COMPETING INTEREST(S)
None.
TRIAL REGISTRATION NUMBER
N/A.
The dynamics of dissolved oxygen in the ocean are of crucial importance for understanding marine ecosystems, with influences ranging from exchange with the atmosphere to biological processes and ...ocean circulation. In this study, we focus on the southern Adriatic Sea, an essential component of the Eastern Mediterranean “conveyor belt”, to investigate long-term oxygen dynamics and its driving factors. We use cross-platform datasets from 2013 to 2020, including remote sensing data, model reanalysis and in-situ observations from Argo floats, ocean gliders and ship-based measurements. Our analysis investigate the interplay of physical, biological and atmospheric forcing that drive oxygen variability. The distribution of dissolved oxygen in the southern Adriatic Sea is influenced by vertical mixing, advection of water masses and ecosystem dynamics. In the surface layer, the variability of dissolved oxygen is triggered by annual primary production and deep convection events. The dynamics in the intermediate and the deep layers are instead primarily influenced by physical processes, such as the vertical mixing and the water masses inflow from the adjacent sub-basins, which is driven by the periodic reversals of northern Ionian Gyre circulation. In particular our study reveals that the water masses advective dynamics driving the increase and decrease of dissolved oxygen have drastically changed in recent years. The highest dissolved oxygen concentrations are currently observed during the northern Ionian Gyre anticyclonic phase, while they have been previously documented during the cyclonic phase. This change appears to be connected with the significant increase in salinity observed in the southern Adriatic Sea in the same period and contributes to a better understanding of the processes that determine oxygen distribution in the Eastern Mediterranean basin.
•Analysis of long-term oxygen dynamics and drivers in the southern Adriatic Sea•Integration of cross-platform dataset•Change in oxygen enrichment and depletion processes were observed in recent years.
The potential impact of rapidly‐evolving submesoscale motions on relative dispersion is at the forefront of physical oceanography, posing challenges for both observations and modeling. A persistent ...coastal front driven by river outflows in the North‐Western Mediterranean Sea is targeted by two observational cruises conducted in the summer of 2010. The frontal zone is sampled using drifters launched with a multi‐scale strategy consisting of modules of triplets, released on either side of the front by small boats. This experiment is original in that the submesoscale range of 100 m to 1000 m is directly targeted, and the results are expected to provide guidance for practical applications, such as prediction of the initial spreading of pollutants and biogeochemical tracers. The influence of submesoscale motions on relative dispersion is quantified using both particle mean square separation as a function of time, and scale‐dependent finite‐size Lyapunov exponents (FSLE,λ(δ)). Our main finding is the identification of a local dispersion regime with values reaching as high as λ ≈ 20 days−1 at drifter pair separation distances of δ < 100 m. This value is more than an order of magnitude greater than that obtained by drifters in the offshore Ligurian current. The Ligurian Sea circulation is modeled using a fully realistic Regional Ocean Modeling System (ROMS) with 1/60° horizontal resolution. It is found that the numerical model significantly underestimates the relative dispersion at submesoscales, indicating the need for particle dispersion parameterizations for unresolved processes.
Key Points
Novel Lagrangian sampling of a persistent submesoscale‐rich coastal front
Identification of local relative dispersion regime
The need for particle transport parameterizations in coastal models
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