200 research outputs found
Coherent ranging with Envisat radar altimeter: a new perspective in analyzing altimeter data using Doppler Processing
ESA's Envisat mission carried a RA-2 radar altimeter since its launch in 2002
to sense sea state and especially measure sea surface height (SSH). The onboard
processing combined multiple echoes incoherently to reduce Speckle noise and
benefit from data compression. In fact, according to past literature the
amplitudes were generally expected to be independent. Nevertheless, samples of
complex data time series of individual echoes (IE) were down-linked and
archived since 2004 for research studies. In this note we demonstrate that
there is sufficient inter-pulse coherence for Doppler processing and we suggest
that the archived data can be re-processed into improved SSH. This is of
particular interest in challenging domains (e.g., coastal zone) where coherent
processing can mitigate errors from ocean surface backscatter inhomogeneity and
nearby land backscatter. A new method called zero-Doppler to process IEs is
thus proposed and discussed
Geological, hydrogeological and hydrogeochemical characterization of groundwater bodies in the Tuscany region (Italy)
This work describes the study for the characterization of meaningful groundwater bodies (CISS, Corpi Idrici Significativi Sotterranei) in Tuscany region (Italy), by way of a multidisciplinary approach, that includes geological and hydrogeological aspects, together with applied hydro-geochemistry
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Managing coastal aquifer salinity under sea level rise using rice cultivation recharge for sustainable land cover
Data Availability:
No data was used for the research described in the article.Code availability:
Upon request.Supplementary material is available online at https://www.sciencedirect.com/science/article/pii/S2214581823001532#sec0095 .Copyright © 2023 The Authors. Study region:
The coastal aquifer of Nile Delta, Egypt is used to develop the current study.
Study focus:
Excess water from rice irrigation is a source of incidental recharge to mitigate seawater intrusion. This paper numerically explores the optimal location of rice cultivations by subdividing the delta domain into three distinct recharging regions (north, central and south). Additionally, SEAWAT code was simulated under a combination of rice cultivation relocation and sea level rise (SLR).
New hydrological insights for the region:
The study findings revealed significant variations in salt volume reduction depending on the location of rice cultivation in the delta. Placing rice cultivation in the northern region resulted in the highest reduction of salt volume (19 %). In contrast, locating the recharge in the central region yielded a salt volume reduction of 0.50 %, while rice cultivation in the southern region produced a 15 % increase. Considering the projected SLR of 61 cm by 2100, there was an overall salt volume increment of 3 %. However, when accounting for both SLR and rice cultivation recharge in the northern region, a substantial salt volume reduction of 17 % was observed. The results demonstrated that incidental recharge by rice cultivation in coastal aquifers is an effective method for enhancing saltwater intrusion control. Moreover, this study improves our understanding of hydrological processes and expected responses in the delta under future climate scenarios
The Genetic Structure and History of Africans and African Americans.
Africa is the source of all modern humans, but characterization of genetic variation and of relationships among populations across the continent has been enigmatic. We studied 121 African populations, four African American populations, and 60 non-African populations for patterns of variation at 1327 nuclear microsatellite and insertion/deletion markers. We identified 14 ancestral population clusters in Africa that correlate with self-described ethnicity and shared cultural and/or linguistic properties. We observed high levels of mixed ancestry in most populations, reflecting historical migration events across the continent. Our data also provide evidence for shared ancestry among geographically diverse hunter-gatherer populations (Khoesan speakers and Pygmies). The ancestry of African Americans is predominantly from Niger-Kordofanian (approximately 71%), European (approximately 13%), and other African (approximately 8%) populations, although admixture levels varied considerably among individuals. This study helps tease apart the complex evolutionary history of Africans and African Americans, aiding both anthropological and genetic epidemiologic studies
Phylogeography of the human mitochondrial haplogroup L3e: a snapshot of African prehistory and Atlantic slave trade
The mtDNA haplogroup L3e, which is identified by the restriction site Â2349 MboI within the
Afro-Eurasian superhaplogroup L3 (®3592 HpaI), is omnipresent in Africa but virtually absent in
Eurasia (except for neighbouring areas with limited genetic exchange). L3e was hitherto poorly
characterised in terms of HVS-I motifs, as the ancestral HVS-I type of L3e cannot be distinguished
from the putative HVS-I ancestor of the entire L3 (differing from the CRS by a transition at np
16223). An MboI screening at np 2349 of a large number of Brazilian and Caribbean mtDNAs
(encompassing numerous mtDNAs of African ancestry), now reveals that L3e is subdivided into four
principal clades, each characterised by a single mutation in HVS-I, with additional support coming
from HVS-II and partial RFLP analysis. The apparently oldest of these clades (transition at np
16327) occurs mainly in central Africa and was probably carried to southern Africa with the Bantu
expansion(s). The most frequent clade (transition at np 16320) testifies to a pronounced expansion
event in the mid-Holocene and seems to be prominent in many Bantu groups from all of Africa. In
contrast, one clade (transition at np 16264) is essentially restricted to Atlantic western Africa
(including Cabo Verde). We propose a tentative L3e phylogeny that is based on 197 HVS-I
sequences. We conclude that haplogroup L3e originated in central or eastern Africa about 46,000
(³14,000) years ago, and was a hitchhiker of much later dispersal and local expansion events, with
the rise of food production and iron smelting. Enforced migration of African slaves to the Americas
translocated L3e mitochondria, the descendants of which in Brazil and the Caribbean still reflect
their different regional African ancestries.info:eu-repo/semantics/publishedVersio
SI-Lab Annual Research Report 2020
The Signal & Images Laboratory (http://si.isti.cnr.it/) is an interdisciplinary research group in computer vision, signal analysis, smart vision systems and multimedia data understanding. It is part of the Institute for Information Science and Technologies of the National Research Council of Italy. This report accounts for the research activities of the Signal and Images Laboratory of the Institute of Information Science and Technologies during the year 2020
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