Melting 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
, 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.
We analyzed the long-term outcome of 4865 patients treated in Studies 82, 87, 88, 91 and 95 for childhood acute lymphoblastic leukemia (ALL) of the Italian Association of Pediatric Hematology and ...Oncology (AIEOP). Treatment was characterized by progressive intensification of systemic therapy and reduction of cranial radiotherapy. A progressive improvement of results with reduction of isolated central nervous system relapse rate was obtained. Ten-year event-free survival increased from 53% in Study 82 to 72% in Study 95, whereas survival improved from 64 to 82%. Since 1991, all patients were treated according to Berlin-Frankfurt-Muenster (BFM) ALL treatment strategy. In Study 91, reduced treatment intensity (25%) yielded inferior results, but intensification of maintenance with high-dose (HD)-L-asparaginase (randomized) allowed to compensate for this disadvantage; in high-risk patients (HR, 15%), substitution of intensive polychemotherapy blocks for conventional BFM backbone failed to improve results. A marked improvement of results was obtained in HR patients when conventional BFM therapy was intensified with three polychemotherapy blocks and double delayed intensification (Study 95). The introduction of minimal residual disease monitoring and evaluation of common randomized questions by AIEOP and BFM groups in the protocol AIEOP-BFM-ALL 2000 are expected to further ameliorate treatment of children with ALL.
The PROMICE (Programme for Monitoring of the Greenland Ice Sheet) aerophotogrammetric map of Greenland ice masses is the first high resolution dataset documenting the mid-1980s areal extent of the ...Greenland Ice Sheet and all the local glaciers and ice caps. The total glacierized area excluding nunataks was 1 804 638 km super(2) plus or minus 2178 km super(2), of which 88 083 plus or minus 1240 km super(2) belonged to local glaciers and ice caps (GIC) substantially independent from the Greenland Ice Sheet. This new result of GIC glacierized area is higher than most previous estimates, 81% greater than Weng's (1995) measurements, but is in line with contemporary findings based on independent data sources. A comparison between our map and the recently released Rastner et al. (2012) inventory and GIMP (Greenland Ice Mapping Project) Ice-Cover Mask (Howat and Negrete, 2013) shows potential for change-assessment studies.
•Devices operating in the harsh environment work at high level of radiation.•Hostile environment is characterized by high level of radiation and magnetic field.•Supplies for the electronic circuits ...often operate in hostile environment.•Long time high reliability operation in presence of magnetic field is mandatory.
The paper deals with the magnetic field (often denoted also as B-field) behavior of Point of Load devices developed in order to meet the requirement in term of magnetic field and radiation hardness mandatory for experiments operating at LHC. Devices have been tested under magnetic field up to about 1.2 T at the Laboratorio Acceleratori e Superconduttività Applicata (LASA), a laboratory located in Milan (Italy). The obtained experimental results are here presented in detail and, finally, discussed. The device here used has been designed to meet the stringent specification given for experiments at LHC taking also into account the planned upgrade for the denoted High Luminosity LHC (HL-LHC). The ability to operate in the hostile environment of the device presented in this paper (a DC-DC converter) is very interesting especially when the device is used in measurement systems: such as the Liquid Argon Calorimeter (LAr) of the ATLAS experiment at CERN. In this case, in fact, the simultaneous presence of radiation and strong static magnetic fields impose particularly harsh working conditions to semiconductor devices, for the presence of radiation, and to the coils, for the presence of magnetic field. In this paper, the experimental results obtained during the tests planned to verify the capability to work in hostile environment of a particular device designed by a research group at CERN has been presented. Details on trend of the output voltage, ripple, efficiency of the device are given and discussed.
•3D thermo-fluid-dynamic modeling of water heat sinks for power converters.•Thermal characterization to validate the numerical model and verify its accuracy.•Comparison of different layouts to ...improve the converter cooling solution.•Performance assessment of the designed heat sink by simulations and measurements.
The aim of this work is to show how it is possible to improve the reliability of a power converter by means of thermal–fluid dynamic numerical analysis. Power electronic converters such as those for High Energy Physics Experiments (HEPEs), must operate in hostile environment with tight thermal constraints and the reliability must be high because of the inaccessibility during the experiments and the high costs of the overall setup. Due to the high power density, the presence of closed environments and the requirement of non-thermal interaction with other subsystems, a liquid cooling system is mandatory. 3D FEM and/or FVM simulations can be used to analyze thermal fluid dynamic behavior of those systems and can be a useful support to design heat sinks optimized for specific applications. We show a comparison of different heat sink solutions to improve the thermal management of a 1.5kW DC/DC hybrid power module.
•Devices operating in the harsh environment are called to work at high level of radiation.•Hostile environment for electronic devices is characterized by both high level of radiation and magnetic ...field.•Equipment devoted to generate the supply for the electronic circuits can be often called to operate in hostile environment.•GaN power devices to be used in PoL converters are very promising.
Devices used in future experiments at LHC will have to work in a very hostile environment. Power supply is a key aspect in this scenario and new converters must be designed in order to meet the future requirements. This is particularly true for Point of Load (PoL) converters that, being located as close as possible to the loads, must operate in a very harsh environment. This paper presents an experimental activity aimed to verify the compliance with a high stationary magnetic field of a commercial PoL, as well as experimental measurements aimed to test the performance of new GaN power devices used in PoL converters.
In particular, a highly integrated commercial PoL converter, that includes in the same package the output filter inductor, is considered for the magnetic test, while an ad-hoc PoL converter, employing 40V, 33A normally off GaN MOSFETs has been designed and, finally, tested. Dynamic RDSon measurements of the same devices are also included.
We present the testbeam results of the first real-time embedded tracking system based on artificial retina algorithm. The tracking system prototype is capable of fast track reconstruction with a ...latency of the response below 1μs and track parameter resolutions that are comparable with the offline results. The artificial retina algorithm was implemented in hardware in a custom data acquisition board based on commercial FPGA. The system was tested successfully using a 180GeV/c proton beam at the CERN SPS with a maximum track rate of about 280kHz. Online track parameters were found in good agreement with offline results and with the simulated response.
•First real-time tracking system based on artificial retina algorithm tested on beam.•Fast track reconstruction within one microsecond latency and offline like quality.•Fast tracking algorithm implemented in commercial FPGAs.
High resolution in situ surface temperature measurements of supraglacial debris cover on Miage Glacier, Mont Blanc Massif, Italy, are compared to ASTER-derived surface temperature data (TIR band, ...acquisition time 10:40 UTC
+
1:00 on 01–08–2005, in the frame of GLIMS project). Spatial patterns of surface temperature and supraglacial debris cover distribution revealed in the two datasets are described. The ground- and remotely sensed temperatures correlate strongly over continuously debris-covered areas (
r
=
0.8), while on partially debris-covered ice (i.e. crevassed areas and ice cliffs) the correlation is weaker (
r
=
0.69 over the whole glacier tongue). A map representing the spatial distribution and thickness of the debris cover is derived from the ASTER surface temperature data using debris-surface temperature–thickness relationships (
r
=
0.8), calculated in 100 m elevation bands. Over <
1 day, surface temperature is influenced by surface meteorological conditions, shading, roughness and elevation; over period of >
1 week, debris thickness is the primary control. Both ground and remotely sensed data predict well the thick debris cover at the terminus and its upstream decrease, and broad cross- and along-glacier patterns of debris thickness are revealed in the ASTER data, e.g. moraines, crevassed areas. Finer details in the debris thickness distribution are not revealed in the ASTER data, due mainly to the coarse 90 m resolution of the thermal-band imagery.
•Devices operating in the harsh environment are called to work at high level of radiation.•SRAM-based FPGA devices are very attractive for latest generation of HEP experiments.•Mitigation techniques ...such as TMR and scrubbing increase the fault tolerance from SEU.
SRAM-based Field Programmable Gate Array (FPGA) logic devices are very attractive in applications where high data throughput is needed, such as the latest generation of High Energy Physics (HEP) experiments. FPGAs have been rarely used in such experiments because of their sensitivity to radiation. The present paper proposes a mitigation approach applied to commercial FPGA devices to meet the reliability requirements for the front-end electronics of the Liquid Argon (LAr) electromagnetic calorimeter of the ATLAS experiment, located at CERN. Particular attention will be devoted to define a proper mitigation scheme of the multi-gigabit transceivers embedded in the FPGA, which is a critical part of the LAr data acquisition chain. A demonstrator board is being developed to validate the proposed methodology. Mitigation techniques such as Triple Modular Redundancy (TMR) and scrubbing will be used to increase the robustness of the design and to maximize the fault tolerance from Single-Event Upsets (SEUs).
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