201 research outputs found

    Ancient agriculture in Southeast Arabia: A three thousand year record of runoff farming from central Oman (Rustaq)

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    Runoff farming is a key hydro-agricultural strategy that has proven efficient in arid areas. Research in Arabia on the function, development, maintenance, durability and abandonment of this technology is scarce. A multiproxy investigation (cartography, sedimentology, pedology, geochemistry, paleo-ecology and chronology) was conducted on a recently abandoned terraced area in Rustaq, Northern Oman. The aim was to characterize the formation, function and management of this runoff system and the driving factors behind its success. Cycles of cultivation were identified during the Iron Age II/III periods (specifically 750–450 BCE), the Early Pre-Islamic Period (PIR) (specifically 350–200 BCE), the Early and Middle Islamic periods (specifically 8–10th C CE, 13th-14th C CE) and the late Islamic period (specifically 17th C CE and later). This expansion and perenniality was possible thanks to: 1- available water (local to micro-regional orogenic precipitation despite a regional aridification during these periods); 2- suitable soils (weathered geological outcrops, probable aeolian /dust particles); 3- a system of production combining crops and husbandry; 4- a progressive increase in agricultural specialization (crops grown and techniques) in parallel with a diversification in hydraulic technology. These results are to some degree in accordance with known phases of settlement intensification and economic growth, but also reveal the persistence of small-scale rural livelihoods during periods of harsh conditions for which archaeological traces are very scarce

    Measuring CP violation and mass ordering in joint long baseline experiments with superbeams

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    We propose to measure the CP phase δCP\delta_{\rm CP}, the magnitude of the neutrino mixing matrix element Ue3|U_{e3}| and the sign of the atmopheric scale mass--squared difference Δm312\Delta{\rm m}^2_{31} with a superbeam by the joint analysis of two different long baseline neutrino oscillation experiments. One is a long baseline experiment (LBL) at 300 km and the other is a very long baseline (VLBL) experiment at 2100 km. We take the neutrino source to be the approved high intensity proton synchrotron, HIPA. The neutrino beam for the LBL is the 2-degree off-axis superbeam and for the VLBL, a narrow band superbeam. Taking into account all possible errors, we evaluate the event rates required and the sensitivities that can be attained for the determination of δCP\delta_{\rm CP} and the sign of Δm312\Delta m^2_{31}. We arrive at a representative scenario for a reasonably precise probe of this part of the neutrino physics.Comment: 25 RevTEX pages, 16 PS figures, revised figure captions and references adde

    Modeling realistic Earth matter density for CP violation in neutrino oscillation

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    We examine the effect of a more realistic Earth matter density model which takes into account of the local density variations along the baseline of a possi ble 2100 km very long baseline neutrino oscillation experiment. Its influence to the measurement of CP violation is investigated and a comparison with the commonly used global density models made. Significant differences are found in the comparison of the results of the different density models.Comment: 16 pages, 8 figure

    Andes, Bofedales, and the Communities of Huascarán National Park, Peru

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    Universidad Nacional Agraria La Molina. Escuela de Posgrado. Maestría en Producción AnimalMountain wetlands are abundant in the high elevations of the tropical Andes. Wetlands occupy ~11% of the total park area and are mostly found in the large mountain valleys. Wetlands occur up to 5000 m asl, but most occur between 4,000–4,700 m asl. The highest elevation wetlands are typically dominated by cushion plants, while lower elevation wetlands are more commonly occupied by graminoids. About 60% of all wetlands are peatlands and the remainder are mineral soil wet meadows. The peatlands are up to 11 m deep and 12,000 years old, storing an average of 2,101 Mg C ha-1, which is comparable to lowland tropical peatlands. Our work in Huascarán National Park in Peru is also showing the importance of wetlands in a coupled natural-human system. These wetlands and alpine landscapes are shaped in part by legacies of past human land use, including ancient pastoralism and farming, and are also affected by millions of downstream users dependent upon wetlands and glacier-fed streams for water and energy production. Biodiversity and endemism is high among taxonomic groups such as plants, birds, fish, amphibians and insects. Currently the tropical Andes are in ecological flux due to rapid land cover changes caused by both biophysical and socioeconomic drivers. In addition, the high Andes are experiencing warming and rapid glacial retreat that is resulting in hydroecological changes and socioeconomic changes to the traditional Andean societies that feed back to changes in wetland sustainability

    Processing Ordinality and Quantity: The Case of Developmental Dyscalculia

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    In contrast to quantity processing, up to date, the nature of ordinality has received little attention from researchers despite the fact that both quantity and ordinality are embodied in numerical information. Here we ask if there are two separate core systems that lie at the foundations of numerical cognition: (1) the traditionally and well accepted numerical magnitude system but also (2) core system for representing ordinal information. We report two novel experiments of ordinal processing that explored the relation between ordinal and numerical information processing in typically developing adults and adults with developmental dyscalculia (DD). Participants made “ordered” or “non-ordered” judgments about 3 groups of dots (non-symbolic numerical stimuli; in Experiment 1) and 3 numbers (symbolic task: Experiment 2). In contrast to previous findings and arguments about quantity deficit in DD participants, when quantity and ordinality are dissociated (as in the current tasks), DD participants exhibited a normal ratio effect in the non-symbolic ordinal task. They did not show, however, the ordinality effect. Ordinality effect in DD appeared only when area and density were randomized, but only in the descending direction. In the symbolic task, the ordinality effect was modulated by ratio and direction in both groups. These findings suggest that there might be two separate cognitive representations of ordinal and quantity information and that linguistic knowledge may facilitate estimation of ordinal information

    Screening of healthcare workers for SARS-CoV-2 highlights the role of asymptomatic carriage in COVID-19 transmission

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    Significant differences exist in the availability of healthcare worker (HCW) SARS-CoV-2 testing between countries, and existing programmes focus on screening symptomatic rather than asymptomatic staff. Over a 3-week period (April 2020), 1,032 asymptomatic HCWs were screened for SARS-CoV-2 in a large UK teaching hospital. Symptomatic staff and symptomatic household contacts were additionally tested. Real-time RT-PCR was used to detect viral RNA from a throat+nose self-swab. 3% of HCWs in the asymptomatic screening group tested positive for SARS-CoV-2. 17/30 (57%) were truly asymptomatic/pauci-symptomatic. 12/30 (40%) had experienced symptoms compatible with coronavirus disease 2019 (COVID-19) >7 days prior to testing, most self-isolating, returning well. Clusters of HCW infection were discovered on two independent wards. Viral genome sequencing showed that the majority of HCWs had the dominant lineage B·1. Our data demonstrates the utility of comprehensive screening of HCWs with minimal or no symptoms. This approach will be critical for protecting patients and hospital staff

    SARS-CoV-2 spike N-terminal domain modulates TMPRSS2-dependent viral entry and fusogenicity

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    The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike N-terminal domain (NTD) remains poorly characterized despite enrichment of mutations in this region across variants of concern (VOCs). Here, we examine the contribution of the NTD to infection and cell-cell fusion by constructing chimeric spikes bearing B.1.617 lineage (Delta and Kappa variants) NTDs and generating spike pseudotyped lentivirus. We find that the Delta NTD on a Kappa or wild-type (WT) background increases S1/S2 cleavage efficiency and virus entry, specifically in lung cells and airway organoids, through use of TMPRSS2. Delta exhibits increased cell-cell fusogenicity that could be conferred to WT and Kappa spikes by Delta NTD transfer. However, chimeras of Omicron BA.1 and BA.2 spikes with a Delta NTD do not show more efficient TMPRSS2 use or fusogenicity. We conclude that the NTD allosterically modulates S1/S2 cleavage and spike-mediated functions in a spike context-dependent manner, and allosteric interactions may be lost when combining regions from more distantly related VOCs
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