366 research outputs found
Quartet S Wave Neutron Deuteron Scattering in Effective Field Theory
The real and imaginary part of the quartet S wave phase shift in nd
scattering (^4 S_{3/2}) for centre-of-mass momenta of up to 300 MeV (E_cm
\approx 70 MeV) is presented in effective field theory, using both perturbative
pions and a theory in which pions are integrated out. As available, the
calculation agrees with both experimental data and potential model
calculations, but extends to a higher, so far untested momentum r\'egime above
the deuteron breakup point. A Lagrangean more feasible for numerical
computations is derived.Comment: 27 pages LaTeX2e with 11 figures, uses packages includegraphicx (6
.eps files), color and feynmp (necessary Metapost files included).
Corrections in bibliography and NNLO results added above breaku
Valuing ecosystem services from wetlands restoration in the Mississippi Alluvial Valley
This study assesses the value of restoring forested wetlands via the U.S. government's Wetlands Reserve Program (WRP) in the Mississippi Alluvial Valley by quantifying and monetizing ecosystem services. The three focal services are greenhouse gas (GHG) mitigation, nitrogen mitigation, and waterfowl recreation. Site-and region-level measurements of these ecosystem services are combined with process models to quantify their production on agricultural land, which serves as the baseline, and on restored wetlands. We adjust and transform these measures into per-hectare, valuation-ready units and monetize them with prices from emerging ecosystem markets and the environmental economics literature. By valuing three of the many ecosystem services produced, we generate lower bound estimates for the total ecosystem value of the wetlands restoration. Social welfare value is found to be between 1486/ha/year, with GHG mitigation valued in the range of 222, nitrogen mitigation at 16. Limited to existing markets, the estimate for annual market value is merely 1035/ha. The estimated social value surpasses the public expenditure or social cost of wetlands restoration in only 1 year, indicating that the return on public investment is very attractive for the WRP. Moreover, the potential market value is substantially greater than landowner opportunity costs, showing that payments to private landowners to restore wetlands could also be profitable for individual landowners
Higher Partial Waves in an Effective Field Theory Approach to nd Scattering
The phase shifts for the higher partial waves (l\ge 1) in the spin quartet
and doublet channel of nd scattering at centre-of-mass energies up to 15 MeV
are presented at next-to-leading and next-to-next-to-leading order in an
effective field theory in which pions are integrated out. As available, the
results agree with both phase shift analyses and potential model calculations.Comment: 23 pages LaTeX2e with 8 figures, uses packages includegraphicx (18
.eps files), amssymb, color and feynmp (necessary Metapost files included).
Petty changes, version for publication in Nucl. Phys.
Abundance, distribution and population trends of Nile crocodile (Crocodylus niloticus) in Gonarezhou National Park, Zimbabwe
The Nile crocodile (Crocodylus niloticus) is an iconic or keystone species in many aquatic ecosystems. In order to understand the abundance, distribution, and population trends of Nile crocodiles in Gonarezhou National Park (GNP), southeastern Zimbabwe, we carried out 4 annual aerial surveys, using a Super Cub aircraft, along 3 major rivers, namely, Save, Runde and Mwenezi, between 2008 and 2011. Our results show that Runde River was characterised by a significant increase in Nile crocodile abundance whereas both Save and Mwenezi rivers were characterised by non-significant increases in Nile crocodile abundance. Overall, we recorded a significant increase in total Nile crocodile population in the three major rivers of the GNP. The non-significant increase in Nile crocodiles in the Mwenezi and Save rivers was likely due to habitat loss, through siltation of large pools, and conflicts with humans, among other factors. We suggest that GNP management should consider halting crocodile egg collection in rivers with low crocodile populations and continuously monitor the crocodile population in the par
Universal sublinear resistivity in vanadium kagome materials hosting charge density waves
The recent discovery of a charge density (CDW) state in ScVSn at
= 91 K offers new opportunities to understand the origins of
electronic instabilities in topological kagome systems. By comparing to the
isostructural non-CDW compound LuVSn, we unravel interesting electrical
transport properties in ScVSn, above and below the charge ordering
temperature. We observed that by applying a magnetic field along the axis,
the temperature behavior of the longitudinal resistivity in ScVSn
changes from metal-like to insulator-like above the CDW transition. We show
that in the charge ordered state ScVSn follows the Fermi liquid
behavior while above that, it transforms into a non-Fermi liquid phase in which
the resistivity varies sublinearly over a broad temperature range. The
sublinear resistivity, which scales by is a common feature among
other vanadium-containing kagome compounds exhibiting CDW states such as
KVSb, RbVSb, and CsVSb. By contrast, the non-Fermi
liquid behavior does not occur in LuVSn. We explain the
universal scaling behavior from the Coulomb scattering between Dirac electrons
and Van Hove singularities; common features in the electronic structure of
kagome materials. Finally, we show anomalous Hall-like behavior in
ScVSn below , which is absent in the Lu compound.
Comparing the transport properties of ScVSn and LuVSn is
valuable to highlight the impacts of the unusual CDW in the Sc compound.Comment: 12 pages, 6 figures. Power law behavior of resistivity as a function
temperature is modified and theoretical explanation is added in the second
versio
Barrett's esophagus: prevalenceâincidence and etiologyâorigins
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86957/1/j.1749-6632.2011.06042.x.pd
Genetics and the Archaeology of Ancient Israel
This paper is a call for DNA testing on ancient skeletal materials from the southern Levant to begin to database genetic information of the inhabitants of this crossroads region. Archaeologists and biblical historians view the earliest presence in the region of a group that called itself Israel in the Iron I period, traditionally dated to ca. 1200-1000 BCE. These were in villages in the varied hill countries of the region, contemporary with urban settlements in the coastal plains, inland valleys, and central Hill Country attributed to varied indigenous groups collectively called Canaanite. The remnants of Egyptian imperial presence in the region lasted until around 1150 BCE, postdating the arrival of an immigrant group from the Aegean called the Philistines ca. 1175 BCE. The period that follows the Iron I in the southern Levant is marked by the development of territorial states throughout the region, ca. 1000-800 BCE. These patrimonial kingdoms, including the United Kingdom of Israel and the divided kingdoms of northern Israel and Judah, coalesced varied peoples under central leadership and newly founded administrative and religious bureaucracies. Ancient DNA testing will give us a further refined understanding of the individuals who peopled the region of the southern Levant throughout its varied archaeological and historic periods, and put forward scientific data that will support, refute, or nuance our socio-historic reconstruction of ancient group identities. These social identities may or may not map onto genetic data, and without sampling of ancient DNA we may never know. A database of ancient DNA will also allow for comparisons with modern DNA samples collected throughout the greater region and the Mediterranean littoral, giving a more robust understanding of the long historical trajectories of regional human genetics and the genetics of varied ancestral groups of todayâs Jewish populations and other cultural groups in the modern Middle East and Mediterranean
DNA Extraction Method Development for Solid Tissues
Although germline variation testing is traditionally performed using DNA obtained from blood or other liquid samples, determining somatic variation in cancer samples requires DNA extraction directly from tissues. Additionally, epigenetic markers, such as 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) are tissue-specific and change in selected disease states. However, several substances present in tissues are known to inhibit downstream reactions, including polymerase chain reaction PCR). For this project, we are assessing the quantity and quality of DNA obtained from extractions of various vital organs using 30 different commercially available DNA extraction kits to determine optimal kits for each tissue
Combating subclonal evolution of resistant cancer phenotypes
Metastatic breast cancer remains challenging to treat, and most patients ultimately progress on therapy. This acquired drug resistance is largely due to drug-refractory sub-populations (subclones) within heterogeneous tumors. Here, we track the genetic and phenotypic subclonal evolution of four breast cancers through years of treatment to better understand how breast cancers become drug-resistant. Recurrently appearing post-chemotherapy mutations are rare. However, bulk and single-cell RNA sequencing reveal acquisition of malignant phenotypes after treatment, including enhanced mesenchymal and growth factor signaling, which may promote drug resistance, and decreased antigen presentation and TNF-α signaling, which may enable immune system avoidance. Some of these phenotypes pre-exist in pre-treatment subclones that become dominant after chemotherapy, indicating selection for resistance phenotypes. Post-chemotherapy cancer cells are effectively treated with drugs targeting acquired phenotypes. These findings highlight cancer's ability to evolve phenotypically and suggest a phenotype-targeted treatment strategy that adapts to cancer as it evolves
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Estimating Global ââBlue Carbonââ Emissions from Conversion and Degradation of Vegetated Coastal Ecosystems
Recent attention has focused on the high rates of annual carbon sequestration in vegetated coastal ecosystemsâmarshes, mangroves, and seagrassesâthat may be lost with habitat destruction (âconversionâ). Relatively unappreciated, however, is that conversion of these coastal ecosystems also impacts very large pools of previously-sequestered carbon. Residing mostly in sediments, this âblue carbonâ can be released to the atmosphere when these ecosystems are converted or degraded. Here we provide the first global estimates of this impact and evaluate its economic implications. Combining the best available data on global area, land-use conversion rates, and near-surface carbon stocks in each of the three ecosystems, using an uncertainty-propagation approach, we estimate that 0.15â1.02 Pg (billion tons) of carbon dioxide are being released annually, several times higher than previous estimates that account only for lost sequestration. These emissions are equivalent to 3â19% of those from deforestation globally, and result in economic damages of $US 6â42 billion annually. The largest sources of uncertainty in these estimates stems from limited certitude in global area and rates of land-use conversion, but research is also needed on the fates of ecosystem carbon upon conversion. Currently, carbon emissions from the conversion of vegetated coastal ecosystems are not included in emissions accounting or carbon market protocols, but this analysis suggests they may be disproportionally important to both. Although the relevant science supporting these initial estimates will need to be refined in coming years, it is clear that policies encouraging the sustainable management of coastal ecosystems could significantly reduce carbon emissions from the land-use sector, in addition to sustaining the well-recognized ecosystem services of coastal habitats
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