3,994 research outputs found
Modelling study of transformations of the exchange flows along the Strait of Gibraltar
Abstract. Vertical transfers of heat, salt and mass between the inflowing
and outflowing layers at the Strait of Gibraltar are explored basing on the outputs of a
three-dimensional fully nonlinear numerical model. The model covers the entire
Mediterranean basin and has a very high spatial resolution around the strait
(1/200∘). Another distinctive feature of the model is that it includes a
realistic barotropic tidal forcing (diurnal and semi-diurnal), in addition to atmospheric
pressure and heat and water surface fluxes. The results show a significant transformation
of the properties of the inflowing and outflowing water masses along their path through
the strait. This transformation is mainly induced by the recirculation of water, and
therefore of heat and salt, between the inflowing and outflowing layers. The underlying
process seems to be the hydraulic control acting at the Espartel section, Camarinal Sill
and Tarifa Narrows, which limits the amount of water that can cross the sections and
forces a vertical recirculation. This results in a complex spatio-temporal pattern of
vertical transfers, with the sign of the net vertical transfer being opposite in each
side of the Camarinal Sill. Conversely, the mixing seems to have little influence on the heat
and salt exchanged between layers (∼2 %–10 % of advected heat and salt).
Therefore, the main point of our work is that most of the transformation of water
properties along the strait is induced by the vertical advection of heat and salt and not
by vertical mixing. A simple relationship between the net flux and the vertical transfers
of water, heat and salt is also proposed. This relationship could be used for the fine-tuning of coarse-resolution model parameterizations in the strait
Thermal Jeans fragmentation within 1000 AU in OMC-1S
We present subarcsecond 1.3 mm continuum ALMA observations towards the Orion
Molecular Cloud 1 South (OMC-1S) region, down to a spatial resolution of 74 AU,
which reveal a total of 31 continuum sources. We also present subarcsecond 7 mm
continuum VLA observations of the same region, which allow to further study
fragmentation down to a spatial resolution of 40 AU. By applying a Mean Surface
Density of Companions method we find a characteristic spatial scale at ~560 AU,
and we use this spatial scale to define the boundary of 19 `cores' in OMC-1S as
groupings of millimeter sources. We find an additional characteristic spatial
scale at ~2900 AU, which is the typical scale of the filaments in OMC-1S,
suggesting a two-level fragmentation process. We measured the fragmentation
level within each core and find a higher fragmentation towards the southern
filament. In addition, the cores of the southern filament are also the densest
(within 1100 AU) cores in OMC-1S. This is fully consistent with previous
studies of fragmentation at spatial scales one order of magnitude larger, and
suggests that fragmentation down to 40 AU seems to be governed by thermal Jeans
processes in OMC-1S.Comment: Accepted to Ap
Not so different after all: Properties and spatial structure of column density peaks in the pipe and Orion A clouds
We present a comparative study of the physical properties and the spatial distribution of column density peaks in two giant molecular clouds (GMCs), the Pipe Nebula and Orion A, which exemplify opposite cases of star cluster formation stages. The density peaks were extracted from dust extinction maps constructed from Herschel/SPIRE far-infrared images. We compare the distribution functions for dust temperature, mass, equivalent radius, and mean volume density of peaks in both clouds, and made a more fair comparison by isolating the less active Tail region in Orion A and by convolving the Pipe Nebula map to simulate placing it at a distance similar to that of the Orion Complex. The peak mass distributions for Orion A, the Tail, and the convolved Pipe have similar ranges, sharing a maximum near 5 M and a similar power-law drop above 10 M. Despite the clearly distinct evolutive stage of the clouds, there are very important similarities in the physical and spatial distribution properties of the column density peaks, pointing to a scenario where they form as a result of uniform fragmentation of filamentary structures across the various scales of the cloud, with density being the parameter leading the fragmentation, and with clustering being a direct result of thermal fragmentation at different spatial scales. Our work strongly supports the idea that the formation of clusters in GMC could be the result of the primordial organization of pre-stellar material
Incorporation of lippia citriodora microwave extract into total-green biogelatin-phospholipid vesicles to improve its antioxidant activity
Phytochemicals from Lippia citriodora leaves were extracted by applying an innovative technology based on the use of microwaves, which represents an alternative method to extract bioactive substances. The obtained extract was incorporated into phospholipid vesicles in order to promote the antioxidant effect of the bioactive molecules present in L. citriodora extract. The extract was analyzed by High Performance Liquid Chromatography coupled to Time-Of-Flight mass spectrometer by electrospray (HPLC-ESI-TOF-MS) and different phytochemicals were detected and quantified. The whole extract was incorporated in liposomes, glycerosomes (liposomes modified with glycerol) and propylene glycol-containing vesicles (PG-PEVs). Moreover, a biopolymer obtained from fish by-product, that is Thunnus albacares skin, was added to improve the bioactivity of the formulations. The in vitro biocompatibility and the antioxidant efficacy of the extract in solution or loaded in the vesicles were tested in primary mouse embryonic fibroblasts (3T3). The results showed the superior bioactivity of the vesicle formulations over the aqueous solution of the extract, which points to an interesting strategy for the treatment of skin disorders
Identification of Importin 8 (IPO8) as the most accurate reference gene for the clinicopathological analysis of lung specimens
<p>Abstract</p> <p>Background</p> <p>The accurate normalization of differentially expressed genes in lung cancer is essential for the identification of novel therapeutic targets and biomarkers by real time RT-PCR and microarrays. Although classical "housekeeping" genes, such as GAPDH, HPRT1, and beta-actin have been widely used in the past, their accuracy as reference genes for lung tissues has not been proven.</p> <p>Results</p> <p>We have conducted a thorough analysis of a panel of 16 candidate reference genes for lung specimens and lung cell lines. Gene expression was measured by quantitative real time RT-PCR and expression stability was analyzed with the softwares <it>GeNorm </it>and <it>NormFinder</it>, mean of |ΔCt| (= |Ct Normal-Ct tumor|) ± SEM, and correlation coefficients among genes. Systematic comparison between candidates led us to the identification of a subset of suitable reference genes for clinical samples: IPO8, ACTB, POLR2A, 18S, and PPIA. Further analysis showed that IPO8 had a very low mean of |ΔCt| (0.70 ± 0.09), with no statistically significant differences between normal and malignant samples and with excellent expression stability.</p> <p>Conclusion</p> <p>Our data show that IPO8 is the most accurate reference gene for clinical lung specimens. In addition, we demonstrate that the commonly used genes GAPDH and HPRT1 are inappropriate to normalize data derived from lung biopsies, although they are suitable as reference genes for lung cell lines. We thus propose IPO8 as a novel reference gene for lung cancer samples.</p
Promoter hypomethylation of the LINE-1 retrotransposable elements activates sense/antisense transcription and marks the progression of chronic myeloid leukemia
Aberrant genome-wide hypomethylation is thought to be
related to tumorigenesis by promoting genomic instability.
Since DNA methylation is considered an important mechanism
for the silencingof retroelements, hypomethylation
in human tumors may lead to their reactivation. However,
the role of DNA hypomethylation in chronic myeloid
leukemia (CML) remains to be elucidated. In this study,
the methylation status of the LINE-1 (L1) retrotransposon
promoter was analysed in CML samples from the chronicphase
(CP, n¼140) and the blast crisis (BC, n¼47). L1
hypomethylation was significantly more frequent in BC
(74.5%) than in CP (38%) (Po0.0001). Furthermore,
L1 hypomethylation led to activation of both ORF1 sense
transcription (Po0.0001) and c-MET gene antisense
transcription (Po0.0001), and was significantly associated
with high levels of BCR–ABL (P¼0.02) and
DNMT3b4 (P¼0.001) transcripts. Interestingly, in
CP-CML, extensive L1 hypomethylation was associated
with poorer prognosis in terms of cytogenetic response
to interferon (P¼0.004) or imatinib (P¼0.034) and
progression-free survival (P¼0.005). The above results
strongly suggest that activation of both sense and
antisense transcriptions by aberrant promoter hypomethylation
of the L1 elements plays a role in the progression
and clinical behavior of the CML
Occupation-Related Differences in the Prevalence of Metabolic Syndrome
OBJECTIVE—To investigate the prevalence of metabolic syndrome in the Spanish working population and determine how the prevalence varies according to occupation and sex
Identification of importin (IPO-8) as the most accurate reference gene for the clinicopathological analysis of lung specimens
Abstract
Background: The accurate normalization of differentially expressed genes in lung cancer is
essential for the identification of novel therapeutic targets and biomarkers by real time RT-PCR
and microarrays. Although classical "housekeeping" genes, such as GAPDH, HPRT1, and beta-actin
have been widely used in the past, their accuracy as reference genes for lung tissues has not been
proven.
Results: We have conducted a thorough analysis of a panel of 16 candidate reference genes for
lung specimens and lung cell lines. Gene expression was measured by quantitative real time RTPCR
and expression stability was analyzed with the softwares GeNorm and NormFinder, mean of
|ΔCt| (= |Ct Normal-Ct tumor|) ± SEM, and correlation coefficients among genes. Systematic
comparison between candidates led us to the identification of a subset of suitable reference genes
for clinical samples: IPO8, ACTB, POLR2A, 18S, and PPIA. Further analysis showed that IPO8 had
a very low mean of |ΔCt| (0.70 ± 0.09), with no statistically significant differences between normal
and malignant samples and with excellent expression stability.
Conclusion: Our data show that IPO8 is the most accurate reference gene for clinical lung
specimens. In addition, we demonstrate that the commonly used genes GAPDH and HPRT1 are
inappropriate to normalize data derived from lung biopsies, although they are suitable as reference
genes for lung cell lines. We thus propose IPO8 as a novel reference gene for lung cancer samples
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