425 research outputs found
Efficient SAR Raw Data Compression in Frequency Domain
SAR raw data compression is necessary to reduce huge amounts of SAR data for a memory on board a satellite, space shuttle or aircraft and for later downlink to a ground station. In view of interferometric and polarimetric applications for SAR data, it becomes more and more important to pay attention to phase errors caused by data compression. Herein, a detailed comparison of block adaptive quantization in time domain (BAQ) and in frequency domain (FFT-BAQ) is given. Inclusion of raw data compression in the processing chain allows an efficient use of the FFT-BAQ and makes implementation for on-board data compression feasible. The FFT-BAQ outperforms the BAQ in terms of signal-to-quantization noise ratio and phase error and allows a direct decimation of the oversampled data equivalent to FIR-filtering in time domain. Impacts on interferometric phase and coherency are also given
Model study of adsorbed metallic quantum dots: Na on Cu(111)
We model electronic properties of the second monolayer Na adatom islands
(quantum dots) on the Cu(111) surface covered homogeneously by the first Na
monolayer. An axially-symmetric three-dimensional jellium model, taking into
account the effects due to the first Na monolayer and the Cu substrate, has
been developed. The electronic structure is solved within the local-density
approximation of the density-functional theory using a real-space multigrid
method. The model enables the study of systems consisting of thousands of
Na-atoms. The results for the local density of states are compared with
differential conductance () spectra and constant current topographs from
Scanning Tunneling Microscopy.Comment: 10 pages, 8 figures. For better quality figures, download
http://www.fyslab.hut.fi/~tto/cylart1.pd
Shifting the paradigm - Applying universal standards of care to Ebola virus disease
As the Democratic Republic of Congo’s
(DRC’s) 10th outbreak of Ebola virus disease
(EVD) rages in this resource-limited, wartorn
region, advances in the delivery of supportive
care and the introduction of investigational
therapies provide a
glimmer of hope amid the mounting
infections. In the absence of
effective therapies or vaccines,
EVD outbreak response has centered
around the most basic of
public health principles — identification
and isolation of patients
with suspected and confirmed
EVD and tracking of all the contacts
of the confirmed patients,
who are then rapidly isolated if
they show signs of disease. This
strategy of “identify, isolate, and
track” allows public health responders
to curtail and eventually
eliminate virus transmission
in the community and has been
the foundation of EVD outbreakcontrol
efforts since the disease
was first described in 1976
Positive biodiversity-productivity relationship predominant in global forests
The biodiversity-productivity relationship (BPR) is foundational to our understanding of the global extinction crisis and its impacts on ecosystem functioning. Understanding BPR is critical for the accurate valuation and effective conservation of biodiversity. Using ground-sourced data from 777,126 permanent plots, spanning 44 countries and most terrestrial biomes, we reveal a globally consistent positive concave-down BPR, showing that continued biodiversity loss would result in an accelerating decline in forest productivity worldwide. The value of biodiversity in maintaining commercial forest productivity alone - US$166 billion to 490 billion per year according to our estimation - is more than twice what it would cost to implement effective global conservation. This highlights the need for a worldwide reassessment of biodiversity values, forest management strategies, and conservation priorities.Peer Reviewe
US hegemony and the origins of Japanese nuclear power : the politics of consent
This paper deploys the Gramscian concepts of hegemony and consent in order to explore the process whereby nuclear power was brought to Japan. The core argument is that nuclear power was brought to Japan as a consequence of US hegemony. Rather than a simple manifestation of one state exerting material ‘power over' another, bringing nuclear power to Japan involved a series of compromises worked out within and between state and civil society in both Japan and the USA. Ideologies of nationalism, imperialism and modernity underpinned the process, coalescing in post-war debates about the future trajectory of Japanese society, Japan's Cold War alliance with the USA and the role of nuclear power in both. Consent to nuclear power was secured through the generation of a psychological state in the public mind combining the fear of nuclear attack and the hope of unlimited consumption in a nuclear-fuelled post-modern world
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