1,351 research outputs found
FAIM-L - SIVA-1: Two Modulators of XIAP in Non-Apoptotic Caspase Function
Alzheimer's disease; Axon remodeling; Synaptic plasticityMalaltia d'Alzheimer; Remodelació axònica; Plasticitat sinàpticaEnfermedad de Alzheimer; Remodelación axónica; Plasticidad sinápticaApoptosis is crucial for the correct development of the nervous system. In adulthood, the same protein machinery involved in programmed cell death can control neuronal adaptiveness through modulation of synaptic pruning and synaptic plasticity processes. Caspases are the main executioners in these molecular pathways, and their strict regulation is essential to perform neuronal remodeling preserving cell survival. FAIM-L and SIVA-1 are regulators of caspase activation. In this review we will focus on FAIM-L and SIVA-1 as two functional antagonists that modulate non-apoptotic caspase activity in neurons. Their participation in long-term depression and neurite pruning will be described in base of the latest studies performed. In addition, the association of FAIM-L non-apoptotic functions with the neurodegeneration process will be reviewed
Supraglacial rivers on the northwest Greenland Ice Sheet, Devon Ice Cap, and Barnes Ice Cap mapped using Sentinel-2 imagery
Supraglacial rivers set efficacy and time lags by which surface meltwater is routed to the englacial, subglacial, and proglacial portions of ice masses. However, these hydrologic features remain poorly studied mainly because they are too narrow (typically <30 m) to be reliably delineated in conventional moderate-resolution satellite images (e.g., 30 m Landsat-8 imagery). This study demonstrates the utility of 10 m Sentinel-2 Multi-Spectral Instrument images to map supraglacial rivers on the northwest Greenland Ice Sheet, Devon Ice Cap, and Barnes Ice Cap, covering a total area of ∼10,000 km2. Sentinel-2 and Landsat-8 both capture overall supraglacial drainage patterns, but Sentinel-2 images are superior to Landsat-8 images for delineating narrow and continuous supraglacial rivers. Sentinel-2 mapping across the three study areas reveals a variety of supraglacial drainage patterns. In northwest Greenland near Inglefield Land, subparallel supraglacial rivers up to 55 km long drain meltwater directly off the ice sheet onto the proglacial zone. On the Devon and the Barnes ice caps, shorter supraglacial rivers (up to 15–30 km long) are commonly interrupted by moulins, which drain internally drained catchments on the ice surface to subglacial systems. We conclude that Sentinel-2 offers strong potential for investigating supraglacial meltwater drainage patterns and improving our understanding of the hydrological conditions of ice masses globally
Urban traffic from the perspective of dual graph
In this paper, urban traffic is modeled using dual graph representation of
urban transportation network where roads are mapped to nodes and intersections
are mapped to links. The proposed model considers both the navigation of
vehicles on the network and the motion of vehicles along roads. The road's
capacity and the vehicle-turning ability at intersections are naturally
incorporated in the model. The overall capacity of the system can be quantified
by a phase transition from free flow to congestion. Simulation results show
that the system's capacity depends greatly on the topology of transportation
networks. In general, a well-planned grid can hold more vehicles and its
overall capacity is much larger than that of a growing scale-free network.Comment: 7 pages, 10 figure
Performance of translucent optical networks under dynamic traffic and uncertain physical-layer information
This paper investigates the performance of translucent
Optical Transport Networks (OTNs) under different traffic
and knowledge conditions, varying from perfect knowledge to
drifts and uncertainties in the physical-layer parameters. Our
focus is on the regular operation of a translucent OTN, i.e., after
the dimensioning and regenerator placement phase. Our contributions
can be summarized as follows. Based on the computation
of the Personick’s Q factor, we introduce a new methodology for
the assessment of the optical signal quality along a path, and
show its application on a realistic example. We analyze the performance
of both deterministic and predictive RWA techniques
integrating this signal quality factor Q in the lightpath computation
process. Our results confirm the effectiveness of predictive
techniques to deal with the typical drifts and uncertainties in the
physical-layer parameters, in contrast to the superior efficacy of
deterministic approaches in case of perfect knowledge. Conversely
to most previous works, where all wavelengths are assumed
to have the same characteristics, we examine the case
when the network is not perfectly compensated, so the Maximum
Transmission Distance (MTD) of the different wavelength channels
may vary. We show that blocking might increase dramatically
when the MTD of the different wavelength channels is overlooked.Postprint (published version
Diverse supraglacial drainage patterns on the Devon ice Cap, Arctic Canada
The Devon Ice Cap (DIC) is one of the largest ice masses in the Canadian Arctic. Each summer, extensive supraglacial river networks develop on the DIC surface and route large volumes of meltwater from ice caps to the ocean. Mapping their extent and understanding their temporal evolution are important for validating runoff routing and melt volumes predicted by regional climate models (RCMs). We use 10 m Sentinel-2 images captured on 28 July and 10/11 August 2016 to map supraglacial rivers across the entire DIC (12,100 km2). Both dendritic and parallel supraglacial drainage patterns are found, with a total length of 44,941 km and a mean drainage density (Dd ) of 3.71 km−1. As the melt season progresses, Dd increases and supraglacial rivers form at progressively higher elevations. There is a positive correlation between RCM-derived surface runoff and satellite-mapped Dd , suggesting that supraglacial drainage density is primarily controlled by surface runoff
Ultraviolet and visible emissions of Er3+ in KY(WO4)2 single crystals co-doped with Yb 3+ ions
Abstract In this paper we studied the luminescence of Er 3+ in KY(WO 4 ) 2 co-doped with Yb 3+ at room temperature and at cryogenic temperature in the 360-860 nm range. We found 13 emissions of erbium in the ultraviolet and visible range, and studied the emissions after two pump wavelengths, one at 981 nm resonant to the maximum absorption of ytterbium and one at 798 nm resonant to the 4 I 9/2 energy level of erbium.
Subglacial lake activity beneath the ablation zone of the Greenland Ice Sheet
Hydrologically active subglacial lakes can drain large volumes of water and sediment along subglacial pathways, affecting the motion and mass balance of ice masses and impacting downstream sediment dynamics. To date, only eight active lakes have been reported beneath the Greenland Ice Sheet (GrIS), and thus the understanding of their spatial distribution and dynamic processes is still lacking. Here, using ICESat-2 (Ice, Cloud, and land Elevation Satellite-2) ATL11 data, we identify 18 active subglacial lakes, 16 of which have not been previously reported. Multi-temporal ArcticDEM (digital elevation model of the Arctic) strip maps were used to extend the time series to verify lakes and determine their drainage history. The identification of active subglacial lakes beneath the GrIS is complicated by the occurrence of supraglacial lakes, which also fill and drain and are hypothesized to be almost co-located. We therefore used the temporal pattern of ice-surface elevation change to discriminate subglacial lakes and utilized the ability of ICESat-2 to penetrate through surface water to correct the elevation provided by the ATL11 data. A significant localized elevation anomaly (−16.03–10.30 m yr−1) was measured in all detected subglacial lakes after correction, revealing that six subglacial lakes are twinned with supraglacial lakes. The active subglacial lakes have large upstream hydrological catchments and are located near or below the equilibrium line. Lakes have a median area of 1.20 km2, and 12 lakes exhibited positive elevation-change rates during the ICESat-2 period. These observations illustrate the potential for combining ICESat-2 and the ArcticDEM to differentiate small subglacial lakes in the ablation zone and beneath supraglacial lakes
The death receptor antagonist FAIM promotes neurite outgrowth by a mechanism that depends on ERK and NF-κB signaling
Fas apoptosis inhibitory molecule (FAIM) is a protein identified as an antagonist of Fas-induced cell death. We show that FAIM overexpression fails to rescue neurons from trophic factor deprivation, but exerts a marked neurite growth–promoting action in different neuronal systems. Whereas FAIM overexpression greatly enhanced neurite outgrowth from PC12 cells and sympathetic neurons grown with nerve growth factor (NGF), reduction of endogenous FAIM levels by RNAi decreased neurite outgrowth in these cells. FAIM overexpression promoted NF-κB activation, and blocking this activation by using a super-repressor IκBα or by carrying out experiments using cortical neurons from mice that lack the p65 NF-κB subunit prevented FAIM-induced neurite outgrowth. The effect of FAIM on neurite outgrowth was also blocked by inhibition of the Ras–ERK pathway. Finally, we show that FAIM interacts with both Trk and p75 neurotrophin receptor NGF receptors in a ligand-dependent manner. These results reveal a new function of FAIM in promoting neurite outgrowth by a mechanism involving activation of the Ras–ERK pathway and NF-κB
Femtosecond-Laser Microstructuring of Ribs on Active (Yb,Nb):RTP/RTP Planar Waveguides
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