Role of daily surface forcing in setting the temperature and mixed layer structure of the Southern Ocean

AbstractOcean stratification and the vertical extent of the mixed layer influence the rate at which the ocean and atmosphere exchange properties. This process has direct impacts for anthropogenic heat and carbon uptake in the Southern Ocean. Submesoscale instabilities that evolve over space (1–10 km) and time (from hours to days) scales directly influence mixed layer variability and are ubiquitous in the Southern Ocean. Mixed layer eddies contribute to mixed layer restratification, while down-front winds, enhanced by strong synoptic storms, can erode stratification by a cross-frontal Ekman buoyancy flux. This study investigates the role of these submesoscale processes on the subseasonal and interannual variability of the mixed layer stratification using four years of high-resolution glider data in the Southern Ocean. An increase of stratification from winter to summer occurs due to a seasonal warming of the mixed layer. However, we observe transient decreases in stratification lasting from days to weeks, which can arrest the seasonal restratification by up to two months after surface heat flux becomes positive. This leads to interannual differences in the timing of seasonal restratification by up to 36 days. Parameterizing the Ekman buoyancy flux in a one-dimensional mixed layer model reduces the magnitude of stratification compared to when the model is run using heat and freshwater fluxes alone. Importantly, the reduced stratification occurs during the spring restratification period, thereby holding important implications for mixed layer dynamics in climate models as well as physical–biological coupling in the Southern Ocean.

Download Full-text

The role of Southern Ocean mixing and upwelling in glacial-interglacial atmospheric CO2change

Tellus B ◽

10.3402/tellusb.v58i1.16793 ◽

2006 ◽

Vol 58 (1) ◽

Author(s):

Andrew J. Watson ◽

Alberto C. Naverira Garabato

Keyword(s):

Southern Ocean ◽

Ocean Mixing

Download Full-text

Functional Specificity of the Members of the Sos Family of Ras-GEF Activators: Novel Role of Sos2 in Control of Epidermal Stem Cell Homeostasis

Cancers ◽

10.3390/cancers13092152 ◽

2021 ◽

Vol 13 (9) ◽

pp. 2152

Author(s):

Fernando C. Baltanás ◽

Cynthia Mucientes-Valdivieso ◽

L. Francisco Lorenzo-Martín ◽

Natalia Fernández-Parejo ◽

Rósula García-Navas ◽

...

Keyword(s):

Stem Cell ◽

Layer Structure ◽

3D Culture ◽

Hair Follicles ◽

Specific Cell ◽

Epidermal Stem Cell ◽

Primary Keratinocytes ◽

Cell Homeostasis ◽

Primary Mouse

Prior reports showed the critical requirement of Sos1 for epithelial carcinogenesis, but the specific functionalities of the homologous Sos1 and Sos2 GEFs in skin homeostasis and tumorigenesis remain unclear. Here, we characterize specific mechanistic roles played by Sos1 or Sos2 in primary mouse keratinocytes (a prevalent skin cell lineage) under different experimental conditions. Functional analyses of actively growing primary keratinocytes of relevant genotypes—WT, Sos1-KO, Sos2-KO, and Sos1/2-DKO—revealed a prevalent role of Sos1 regarding transcriptional regulation and control of RAS activation and mechanistic overlapping of Sos1 and Sos2 regarding cell proliferation and survival, with dominant contribution of Sos1 to the RAS-ERK axis and Sos2 to the RAS-PI3K/AKT axis. Sos1/2-DKO keratinocytes could not grow under 3D culture conditions, but single Sos1-KO and Sos2-KO keratinocytes were able to form pseudoepidermis structures that showed disorganized layer structure, reduced proliferation, and increased apoptosis in comparison with WT 3D cultures. Remarkably, analysis of the skin of both newborn and adult Sos2-KO mice uncovered a significant reduction of the population of stem cells located in hair follicles. These data confirm that Sos1 and Sos2 play specific, cell-autonomous functions in primary keratinocytes and reveal a novel, essential role of Sos2 in control of epidermal stem cell homeostasis.

Download Full-text

A numerical study on the role of atmospheric forcing on mixed layer depth variability in the Bay of Bengal using a regional ocean model

Ocean Dynamics ◽

10.1007/s10236-021-01475-8 ◽

2021 ◽

Author(s):

Sumit Dandapat ◽

Arun Chakraborty ◽

Jayanarayanan Kuttippurath ◽

Chirantan Bhagawati ◽

Radharani Sen

Keyword(s):

Mixed Layer ◽

Bay Of Bengal ◽

Numerical Study ◽

Mixed Layer Depth ◽

Ocean Model ◽

Atmospheric Forcing ◽

Layer Depth ◽

Regional Ocean Model

Download Full-text

How Can We Manage Gallbladder Lesions by Transabdominal Ultrasound?

Diagnostics ◽

10.3390/diagnostics11050784 ◽

2021 ◽

Vol 11 (5) ◽

pp. 784

Author(s):

Shinji Okaniwa

Keyword(s):

High Frequency ◽

Layer Structure ◽

Wall Layer ◽

Pancreaticobiliary Maljunction ◽

Doppler Imaging ◽

Wall Thickening ◽

Contrast Enhanced ◽

Postural Changes ◽

Venous Phase

The most important role of ultrasound (US) in the management of gallbladder (GB) lesions is to detect lesions earlier and differentiate them from GB carcinoma (GBC). To avoid overlooking lesions, postural changes and high-frequency transducers with magnified images should be employed. GB lesions are divided into polypoid lesions (GPLs) and wall thickening (GWT). For GPLs, classification into pedunculated and sessile types should be done first. This classification is useful not only for the differential diagnosis but also for the depth diagnosis, as pedunculated carcinomas are confined to the mucosa. Both rapid GB wall blood flow (GWBF) and the irregularity of color signal patterns on Doppler imaging, and heterogeneous enhancement in the venous phase on contrast-enhanced ultrasound (CEUS) suggest GBC. Since GWT occurs in various conditions, subdividing into diffuse and focal forms is important. Unlike diffuse GWT, focal GWT is specific for GB and has a higher incidence of GBC. The discontinuity and irregularity of the innermost hyperechoic layer and irregular or disrupted GB wall layer structure suggest GBC. Rapid GWBF is also useful for the diagnosis of wall-thickened type GBC and pancreaticobiliary maljunction. Detailed B-mode evaluation using high-frequency transducers, combined with Doppler imaging and CEUS, enables a more accurate diagnosis.

Download Full-text