300 research outputs found
An improved algorithm for polar cloud-base detection by ceilometer over the ice sheets
Optically thin ice and mixed-phase clouds play an important role in polar
regions due to their effect on cloud radiative impact and precipitation.
Cloud-base heights can be detected by ceilometers, low-power backscatter
lidars that run continuously and therefore have the potential to provide
basic cloud statistics including cloud frequency, base height and vertical
structure. The standard cloud-base detection algorithms of ceilometers are
designed to detect optically thick liquid-containing clouds, while the
detection of thin ice clouds requires an alternative approach. This paper
presents the polar threshold (PT) algorithm that was developed to be
sensitive to optically thin hydrometeor layers (minimum optical depth
τ ≥ 0.01). The PT algorithm detects the first hydrometeor layer
in a vertical attenuated backscatter profile exceeding a predefined threshold
in combination with noise reduction and averaging procedures. The optimal
backscatter threshold of 3 × 10<sup>−4</sup> km<sup>−1</sup> sr<sup>−1</sup> for
cloud-base detection near the surface was derived based on a sensitivity
analysis using data from Princess Elisabeth, Antarctica and Summit,
Greenland. At higher altitudes where the average noise level is higher than
the backscatter threshold, the PT algorithm becomes signal-to-noise ratio
driven. The algorithm defines cloudy conditions as any atmospheric profile
containing a hydrometeor layer at least 90 m thick. A comparison with
relative humidity measurements from radiosondes at Summit illustrates the
algorithm's ability to significantly discriminate between clear-sky and
cloudy conditions. Analysis of the cloud statistics derived from the PT
algorithm indicates a year-round monthly mean cloud cover fraction of 72%
(±10%) at Summit without a seasonal cycle. The occurrence of
optically thick layers, indicating the presence of supercooled liquid water
droplets, shows a seasonal cycle at Summit with a monthly mean summer peak of
40 % (±4%). The monthly mean cloud occurrence frequency in summer
at Princess Elisabeth is 46% (±5%), which reduces to 12%
(±2.5%) for supercooled liquid cloud layers. Our analyses
furthermore illustrate the importance of optically thin hydrometeor layers
located near the surface for both sites, with 87% of all detections below
500 m for Summit and 80% below 2 km for Princess Elisabeth. These
results have implications for using satellite-based remotely sensed cloud
observations, like CloudSat that may be insensitive for hydrometeors near
the surface. The decrease of sensitivity with height, which is an inherent
limitation of the ceilometer, does not have a significant impact on our
results. This study highlights the potential of the PT algorithm to extract
information in polar regions from various hydrometeor layers using
measurements by the robust and relatively low-cost ceilometer instrument
Observations of Buried Lake Drainage on the Antarctic Ice Sheet.
Between 1992 and 2017, the Antarctic Ice Sheet (AIS) lost ice equivalent to 7.6 ± 3.9 mm of sea level rise. AIS mass loss is mitigated by ice shelves that provide a buttress by regulating ice flow from tributary glaciers. However, ice-shelf stability is threatened by meltwater ponding, which may initiate, or reactivate preexisting, fractures, currently poorly understood processes. Here, through ground penetrating radar (GPR) analysis over a buried lake in the grounding zone of an East Antarctic ice shelf, we present the first field observations of a lake drainage event in Antarctica via vertical fractures. Concurrent with the lake drainage event, we observe a decrease in surface elevation and an increase in Sentinel-1 backscatter. Finally, we suggest that fractures that are initiated or reactivated by lake drainage events in a grounding zone will propagate with ice flow onto the ice shelf itself, where they may have implications for its stability
Metastatic primary adenocarcinoma of the bladder in a twenty-five years old woman
Primary adenocarcinoma of the bladder is a rare tumor. The classification between primary vesical and urachal is debated. We present the case of a young female who presented clinicopathological features of a metastatic urachal adenocarcinoma, but the histological result revealed primary adenocarcinoma of the bladder contrary to expectancy. To the best of our knowledge this is the first reported case of a metastatic adenocarcinoma of the bladder in a 25 years old female. This case emphasizes the challenge for urologists to recognize and manage this aggressive tumor in the setting described
Wernicke's region--where is it
In this subject, the first question both logically and chronologically was and is: Can a lesion (focal damage) of the cerebrum cause a loss of language without causing a loss of intelligence? That is the original question, still debated hotly by many people. Much of the heat is attributable to the way in which the question is phrased. Suppose we phrase it relatively, as follows: Can a lesion of the cerebrum produce a deficit in language that is far in excess of the concomitant deficit in intelligence? Asked in this way, almost everyone would answer yes. There are worthy persons who are still arguing that anyone who has a loss of language from a cerebral lesion must have some accompanying loss of intelligence. Similarly, there are equally worthy persons recurrently showing us that intelligence can be preserved in spite of severe aphasia. Both parties are undoubtedly correct. But the force of either argument is largely dissipated when the question is rephrased in the relative way. Of course, how much intelligence is lost (or retained) depends upon how one goes about measuring intelligence; but with almost any measures, except those strictly linguistic, the answer will be yes. Indeed, if the answer were not yes, there would not be such a thing a
Hypoxic Environment and Paired Hierarchical 3D and 2D Models of Pediatric H3.3-Mutated Gliomas Recreate the Patient Tumor Complexity.
BACKGROUND:Pediatric high-grade gliomas (pHGGs) are facing a very dismal prognosis and representative pre-clinical models are needed for new treatment strategies. Here, we examined the relevance of collecting functional, genomic, and metabolomics data to validate patient-derived models in a hypoxic microenvironment. METHODS:From our biobank of pediatric brain tumor-derived models, we selected 11 pHGGs driven by the histone H3.3K28M mutation. We compared the features of four patient tumors to their paired cell lines and mouse xenografts using NGS (next generation sequencing), aCGH (array comparative genomic hybridization), RNA sequencing, WES (whole exome sequencing), immunocytochemistry, and HRMAS (high resolution magic angle spinning) spectroscopy. We developed a multicellular in vitro model of cell migration to mimic the brain hypoxic microenvironment. The live cell technology Incucyte© was used to assess drug responsiveness in variable oxygen conditions. RESULTS:The concurrent 2D and 3D cultures generated from the same tumor sample exhibited divergent but complementary features, recreating the patient intra-tumor complexity. Genomic and metabolomic data described the metabolic changes during pHGG progression and supported hypoxia as an important key to preserve the tumor metabolism in vitro and cell dissemination present in patients. The neurosphere features preserved tumor development and sensitivity to treatment. CONCLUSION:We proposed a novel multistep work for the development and validation of patient-derived models, considering the immature and differentiated content and the tumor microenvironment of pHGGs
Evaluation of the CloudSat surface snowfall product over Antarctica using ground-based precipitation radars
In situ observations of snowfall over the Antarctic Ice Sheet are scarce.
Currently, continent-wide assessments of snowfall are limited to information
from the Cloud Profiling Radar on board the CloudSat satellite, which has not been evaluated up to now. In this study,
snowfall derived from CloudSat is evaluated using three ground-based
vertically profiling 24 GHz precipitation radars (Micro Rain Radars: MRRs).
Firstly, using the MRR long-term measurement records, an assessment of the
uncertainty caused by the low temporal sampling rate of CloudSat (one revisit
per 2.1 to 4.5 days) is performed. The 10–90th-percentile temporal sampling
uncertainty in the snowfall climatology varies between 30 % and 40 %
depending on the latitudinal location and revisit time of CloudSat. Secondly,
an evaluation of the snowfall climatology indicates that the CloudSat
product, derived at a resolution of 1∘ latitude by 2∘
longitude, is able to accurately represent the snowfall climatology at the
three MRR sites (biases < 15 %), outperforming ERA-Interim. For coarser
and finer resolutions, the performance drops as a result of higher omission
errors by CloudSat. Moreover, the CloudSat product does not perform well in
simulating individual snowfall events. Since the difference between the MRRs
and the CloudSat climatology are limited and the temporal uncertainty is
lower than current Climate Model Intercomparison Project Phase 5 (CMIP5)
snowfall variability, our results imply that the CloudSat product is valuable
for climate model evaluation purposes.</p
Characterization of the transcriptional and metabolic responses of pediatric high grade gliomas to mTOR-HIF-1α axis inhibition.
Pediatric high grade glioma (pHGGs), including sus-tentorial and diffuse intrinsic pontine gliomas, are known to have a very dismal prognosis. For instance, even an increased knowledge on molecular biology driving this brain tumor entity, there is no treatment able to cure those patients. Therefore, we were focusing on a translational pathway able to increase the cell resistance to treatment and to reprogram metabolically tumor cells, which are, then, adapting easily to a hypoxic microenvironment. To establish, the crucial role of the hypoxic pathways in pHGGs, we, first, assessed their protein and transcriptomic deregulations in a pediatric cohort of pHGGs and in pHGG's cell lines, cultured in both normoxic and hypoxic conditions. Secondly, based on the concept of a bi-therapy targeting in pHGGs mTORC1 (rapamycin) and HIF-1α (irinotecan), we hypothesized that the balanced expressions between RAS/ERK, PI3K/AKT and HIF-1α/HIF-2α/MYC proteins or genes may provide a modulation of the cell response to this double targeting. Finally, we could evidence three protein, genomic and metabolomic profiles of response to rapamycin combined with irinotecan. The pattern of highly sensitive cells to mTOR/HIF-1α targeting was linked to a MYC/ERK/HIF-1α over-expression and the cell resistance to a major hyper-expression of HIF-2α
Naturalizing Dasein and other (Alleged) Heresies
First paragraph: To my mind, being wrong is nowhere near as disheartening as being boring, so I am encouraged by the fact that, in the four chapters immediately preceding this one, four thinkers for whom I have nothing but the utmost intellectual respect have found my ongoing project to articulate the philosophical groundwork for a genuinely Heideggerian cognitive science interesting enough that they have taken the trouble to explain precisely why it is flawed. Just how deep the supposed flaws go depends on which set of criticisms one chooses to read. For Ratcliffe and Rehberg they go very deep indeed, since, for these thinkers, there is a sense in which the very idea of a Heideggerian cognitive science borders on the incoherent. Dreyfus and Rietveld, on the other hand, seem to agree with me that something worth calling a Heideggerian cognitive science is certainly possible; it's just that my version of it is seriously defective
Does Observation of Postural Imbalance Induce a Postural Reaction?
Import JabRef | WosArea Life Sciences and Biomedicine - Other TopicsInternational audienceBackground: Several studies bring evidence that action observation elicits contagious responses during social interactions. However automatic imitative tendencies are generally inhibited and it remains unclear in which conditions mere action observation triggers motor behaviours. In this study, we addressed the question of contagious postural responses when observing human imbalance. Methodology/Principal Findings: We recorded participants' body sway while they observed a fixation cross (control condition), an upright point-light display of a gymnast balancing on a rope, and the same point-light display presented upside down. Our results showed that, when the upright stimulus was displayed prior to the inverted one, centre of pressure area and antero-posterior path length were significantly greater in the upright condition compared to the control and upside down conditions. Conclusions/Significance: These results demonstrate a contagious postural reaction suggesting a partial inefficiency of inhibitory processes. Further, kinematic information was sufficient to trigger this reaction. The difference recorded between the upright and upside down conditions indicates that the contagion effect was dependent on the integration of gravity constraints by body kinematics. Interestingly, the postural response was sensitive to habituation, and seemed to disappear when the observer was previously shown an inverted display. The motor contagion recorded here is consistent with previous work showing vegetative output during observation of an effortful movement and could indicate that lower level control facilitates contagion effects
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