451 research outputs found

    A daily, 1 km resolution data set of downscaled Greenland ice sheet surface mass balance (1958–2015)

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    This study presents a data set of daily, 1 km resolution Greenland ice sheet (GrIS) surface mass balance (SMB) covering the period 1958–2015. Applying corrections for elevation, bare ice albedo and accumulation bias, the high-resolution product is statistically downscaled from the native daily output of the polar regional climate model RACMO2.3 at 11 km. The data set includes all individual SMB components projected to a down-sampled version of the Greenland Ice Mapping Project (GIMP) digital elevation model and ice mask. The 1 km mask better resolves narrow ablation zones, valley glaciers, fjords and disconnected ice caps. Relative to the 11 km product, the more detailed representation of isolated glaciated areas leads to increased precipitation over the southeastern GrIS. In addition, the downscaled product shows a significant increase in runoff owing to better resolved low-lying marginal glaciated regions. The combined corrections for elevation and bare ice albedo markedly improve model agreement with a newly compiled data set of ablation measurements

    An improved algorithm for polar cloud-base detection by ceilometer over the ice sheets

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    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 &geq; 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>&minus;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

    Neonatal Oral Imitation in Patients with Severe Brain Damage

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    Background: Neonates reproduce facial movements in response to an adult model just after birth. This neonatal oral imitation usually disappears at about 2- to 3-months of age following the development of cortical control. There is controversy relating to the nature and neural basis of such neonatal imitation. To address this issue, we studied the relationship between oral imitation, primitive reflexes, and residual voluntary movement in patients with severe brain damage. Methods: Six male and six female patients with cerebral palsy, from 4 to 39 years, were included in this study. Oral imitation was examined when they were awake and looked at the experimenter. Patients were evaluated as performing oral imitation when they opened their mouth repeatedly without visual feedback regarding their own behavior in response to the experimenter’s oral movement. Tongue or lip protrusion was not examined because none of patients were able to do those behaviors due to their physical disability. Rooting and sucking reflexes were also investigated as representatives of primitive reflexes. Results: Six patients (50%) performed oral imitation. Mouth opening was not observed repeatedly in response to other facial expression without opening the mouth such as surprise or smile, excluding the possibility of nonspecific oral reaction. They exhibited little voluntary movement of their extremities. Half of them also manifested at least one primitive reflex. N

    Wernicke's region--where is it

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    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

    Effect of Tumor-Treating Fields Plus Maintenance Temozolomide vs Maintenance Temozolomide Alone on Survival in Patients With Glioblastoma: A Randomized Clinical Trial.

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    Tumor-treating fields (TTFields) is an antimitotic treatment modality that interferes with glioblastoma cell division and organelle assembly by delivering low-intensity alternating electric fields to the tumor. To investigate whether TTFields improves progression-free and overall survival of patients with glioblastoma, a fatal disease that commonly recurs at the initial tumor site or in the central nervous system. In this randomized, open-label trial, 695 patients with glioblastoma whose tumor was resected or biopsied and had completed concomitant radiochemotherapy (median time from diagnosis to randomization, 3.8 months) were enrolled at 83 centers (July 2009-2014) and followed up through December 2016. A preliminary report from this trial was published in 2015; this report describes the final analysis. Patients were randomized 2:1 to TTFields plus maintenance temozolomide chemotherapy (n = 466) or temozolomide alone (n = 229). The TTFields, consisting of low-intensity, 200 kHz frequency, alternating electric fields, was delivered (≥ 18 hours/d) via 4 transducer arrays on the shaved scalp and connected to a portable device. Temozolomide was administered to both groups (150-200 mg/m2) for 5 days per 28-day cycle (6-12 cycles). Progression-free survival (tested at α = .046). The secondary end point was overall survival (tested hierarchically at α = .048). Analyses were performed for the intent-to-treat population. Adverse events were compared by group. Of the 695 randomized patients (median age, 56 years; IQR, 48-63; 473 men [68%]), 637 (92%) completed the trial. Median progression-free survival from randomization was 6.7 months in the TTFields-temozolomide group and 4.0 months in the temozolomide-alone group (HR, 0.63; 95% CI, 0.52-0.76; P &lt; .001). Median overall survival was 20.9 months in the TTFields-temozolomide group vs 16.0 months in the temozolomide-alone group (HR, 0.63; 95% CI, 0.53-0.76; P &lt; .001). Systemic adverse event frequency was 48% in the TTFields-temozolomide group and 44% in the temozolomide-alone group. Mild to moderate skin toxicity underneath the transducer arrays occurred in 52% of patients who received TTFields-temozolomide vs no patients who received temozolomide alone. In the final analysis of this randomized clinical trial of patients with glioblastoma who had received standard radiochemotherapy, the addition of TTFields to maintenance temozolomide chemotherapy vs maintenance temozolomide alone, resulted in statistically significant improvement in progression-free survival and overall survival. These results are consistent with the previous interim analysis. clinicaltrials.gov Identifier: NCT00916409

    Naturalizing Dasein and other (Alleged) Heresies

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    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

    A tipping point in refreezing accelerates mass loss of Greenland's glaciers and ice caps.

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    peer reviewedMelting of the Greenland ice sheet (GrIS) and its peripheral glaciers and ice caps (GICs) contributes about 43% to contemporary sea level rise. While patterns of GrIS mass loss are well studied, the spatial and temporal evolution of GICs mass loss and the acting processes have remained unclear. Here we use a novel, 1 km surface mass balance product, evaluated against in situ and remote sensing data, to identify 1997 (±5 years) as a tipping point for GICs mass balance. That year marks the onset of a rapid deterioration in the capacity of the GICs firn to refreeze meltwater. Consequently, GICs runoff increases 65% faster than meltwater production, tripling the post-1997 mass loss to 36±16 Gt-1, or ∼14% of the Greenland total. In sharp contrast, the extensive inland firn of the GrIS retains most of its refreezing capacity for now, buffering 22% of the increased meltwater production. This underlines the very different response of the GICs and GrIS to atmospheric warming

    Two cilengitide regimens in combination with standard treatment for patients with newly diagnosed glioblastoma and unmethylated MGMT gene promoter: results of the open-label, controlled, randomized phase II CORE study.

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    BACKGROUND: Survival outcomes for patients with glioblastoma remain poor, particularly for patients with unmethylated O(6)-methylguanine-DNA methyltransferase (MGMT) gene promoter. This phase II, randomized, open-label, multicenter trial investigated the efficacy and safety of 2 dose regimens of the selective integrin inhibitor cilengitide combined with standard chemoradiotherapy in patients with newly diagnosed glioblastoma and an unmethylated MGMT promoter. METHODS: Overall, 265 patients were randomized (1:1:1) to standard cilengitide (2000 mg 2×/wk; n = 88), intensive cilengitide (2000 mg 5×/wk during wk 1-6, thereafter 2×/wk; n = 88), or a control arm (chemoradiotherapy alone; n = 89). Cilengitide was administered intravenously in combination with daily temozolomide (TMZ) and concomitant radiotherapy (RT; wk 1-6), followed by TMZ maintenance therapy (TMZ/RT→TMZ). The primary endpoint was overall survival; secondary endpoints included progression-free survival, pharmacokinetics, and safety and tolerability. RESULTS: Median overall survival was 16.3 months in the standard cilengitide arm (hazard ratio [HR], 0.686; 95% CI: 0.484, 0.972; P = .032) and 14.5 months in the intensive cilengitide arm (HR, 0.858; 95% CI: 0.612, 1.204; P = .3771) versus 13.4 months in the control arm. Median progression-free survival assessed per independent review committee was 5.6 months (HR, 0.822; 95% CI: 0.595, 1.134) and 5.9 months (HR, 0.794; 95% CI: 0.575, 1.096) in the standard and intensive cilengitide arms, respectively, versus 4.1 months in the control arm. Cilengitide was well tolerated. CONCLUSIONS: Standard and intensive cilengitide dose regimens were well tolerated in combination with TMZ/RT→TMZ. Inconsistent overall survival and progression-free survival outcomes and a limited sample size did not allow firm conclusions regarding clinical efficacy in this exploratory phase II study
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