6,580 research outputs found
Why have poverty and income inequality increased so much? Argentina 1991-2002
This paper analyzes the sources of changes in poverty and income inequality among Argentine households during the 1991-2001 period. We assess the eect of changes in labor market participation, unemployment, education levels, and returns to human capital on income inequality and poverty by using a micro-simulation approach. This procedure allows us to evaluate the impact of each one of those changes on several measures of income inequality and poverty during the nineties. We found that unemployment accounts for a large part of the increase in income inequality and poverty that this country experienced in the last decade. In January 2002, Argentina declared the default on its external debt and devaluated the peso 40% ending the convertibility period. Since then, a growing inflation is aecting the purchasing power of Argentine households for the first time in more than ten years. Using our methodology we estimate the eect of the emerging inflation on poverty among households. Our findings indicate that inflation increases poverty significantly at least in the short run.
Inelastic light scattering and the excited states of many-electron quantum dots
A consistent calculation of resonant inelastic (Raman) scattering amplitudes
for relatively large quantum dots, which takes account of valence-band mixing,
discrete character of the spectrum in intermediate and final states, and
interference effects, is presented. Raman peaks in charge and spin channels are
compared with multipole strengths and with the density of energy levels in
final states. A qualitative comparison with the available experimental results
is given.Comment: 5 pages, accepted in J. Phys.: Condens. Matte
How single-trial electrical neuroimaging contributes to multisensory research
This study details a method to statistically determine, on a millisecond scale and for individual subjects, those brain areas whose activity differs between experimental conditions, using single-trial scalp-recorded EEG data. To do this, we non-invasively estimated local field potentials (LFPs) using the ELECTRA distributed inverse solution and applied non-parametric statistical tests at each brain voxel and for each time point. This yields a spatio-temporal activation pattern of differential brain responses. The method is illustrated here in the analysis of auditory-somatosensory (AS) multisensory interactions in four subjects. Differential multisensory responses were temporally and spatially consistent across individuals, with onset at ~50ms and superposition within areas of the posterior superior temporal cortex that have traditionally been considered auditory in their function. The close agreement of these results with previous investigations of AS multisensory interactions suggests that the present approach constitutes a reliable method for studying multisensory processing with the temporal and spatial resolution required to elucidate several existing questions in this field. In particular, the present analyses permit a more direct comparison between human and animal studies of multisensory interactions and can be extended to examine correlation between electrophysiological phenomena and behavio
Non-Invasive Estimates of Local Field Potentials for Brain-Computer Interfaces: Theoretical Derivation and Comparison with Direct Intracranial Recordings
Spatiotemporal scales and links between electrical neuroimaging modalities
Recordings of brain electrophysiological activity provide the most direct reflect of neural function. Information contained in these signals varies as a function of the spatial scale at which recordings are done: from single cell recording to large scale macroscopic fields, e.g., scalp EEG. Microscopic and macroscopic measurements and models in Neuroscience are often in conflict. Solving this conflict might require the developments of a sort of bio-statistical physics, a framework for relating the microscopic properties of individual cells to the macroscopic or bulk properties of neural circuits. Such a framework can only emerge in Neuroscience from the systematic analysis and modeling of the diverse recording scales from simultaneous measurements. In this article we briefly review the different measurement scales and models in modern neuroscience to try to identify the sources of conflict that might ultimately help to create a unified theory of brain electromagnetic fields. We argue that seen the different recording scales, from the single cell to the large scale fields measured by the scalp electroencephalogram, as derived from a unique physical magnitude—the electric potential that is measured in all cases—might help to conciliate microscopic and macroscopic models of neural function as well as the animal and human neuroscience literatur
Determining the nuclear neutron distribution from Coherent Elastic neutrino-Nucleus Scattering: current results and future prospects
Coherent elastic neutrino-nucleus scattering (CENS), a process recently
measured for the first time at ORNL's Spallation Neutron Source, is directly
sensitive to the weak form factor of the nucleus. The European Spallation
Source (ESS), presently under construction, will generate the most intense
pulsed neutrino flux suitable for the detection of CENS. In this paper we
quantify its potential to determine the root mean square radius of the
point-neutron distribution, for a variety of target nuclei and a suite of
detectors. To put our results in context we also derive, for the first time, a
constraint on this parameter from the analysis of the energy and timing data of
the CsI detector at the COHERENT experiment.Comment: 16 pages, 4 figures. Minor text changes and references added. Matches
version accepted by JHE
Fast algorithm for H.264/AVC intra prediction based on discrete wavelet transform
H.264 or MPEG-4 AVC (Advanced Video Coding) is the new world-wide accepted international Standard for video coding, approved by ITU-T and ISO. New Tools have been added to improve the coding efficiency allowing a save up above of 50%, when is compared with previous standards (H.263, MPEG-2 y MPEG-4). From April 2007 there is a new set of profiles known as “all-Intra”. They were born as a sub-set from the “High” profile and have reached a high impact within broadcast industry where the highest quality video formats are demanded. The high efficiency of “all-Intra” mode in H.264 is due to Rate Distortion Optimization (RDO) technique. RDO chooses for each macroblock (MB) the best partition mode and directional prediction. However, the computational burden becomes extremely high due to huge number of prediction-prediction modes that should be evaluated. This article shows a new algorithm for fast partition mode algorithm based on Discrete Wavelet Transform (DWT). It allows reducing the number of candidate modes to those which are strictly defined for each partition. By using the local 2D-DWT over each MB, information of the homogeneity is obtained. It is got from multiresolution analysis of the transformed coefficients in each sub-band. This way it is easier to classify quickly the optimum partition mode avoiding the exhaustive seek made by RDO
Exploring the role of GATA2 in normal and malignant haematopoiesis
Haematopoietic stem cells (HSCs) are multipotent stem cells that sustain long-life
haematopoiesis. External signals delivered from the bone marrow (BM) niche are
crucial for HSC homeostasis, alongside a cell intrinsic transcriptional program driven
by transcription factors (TFs). Translocations, epigenetic and genetic mutations
altering TF activity, subvert HSC homeostasis leading to the development of preleukaemic
stem cells (pre-LSCs) and LSCs that drive the development and
maintenance of acute myeloid leukaemia (AML). Gata2, a zinc finger TF expressed
in the haematopoietic system, is essential for the generation and survival of HSCs in
development, however the requirement for Gata2 in adult HSCs is less clear.
Perturbation of GATA2 function by loss of function mutations of the GATA2 gene,
gives rise to immunodeficiency syndromes with a high risk of transformation to
myelodysplastic syndrome and AML. Conversely, overexpression of GATA2 is
observed in approximately 40% of AML patients and has been linked with poor
prognosis. However, the precise biological impact of GATA2 expression on AML cell
fate, including LSCs, has yet to be interrogated
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