We report results from searches for new physics with low-energy electronic recoil data recorded with the XENON1T detector. With an exposure of 0.65 tonne-years and an unprecedentedly low background ...rate of 76 ± 2stat events/(tonne × year × keVÞ between 1 and 30 keV, the data enable one of the most sensitive searches for solar axions, an enhanced neutrino magnetic moment using solar neutrinos, and bosonic dark matter. An excess over known backgrounds is observed at low energies and most prominent between 2 and 3 keV. The solar axion model has a 3.4σ significance, and a three-dimensional 90% confidence surface is reported for axion couplings to electrons, photons, and nucleons. This surface is inscribed in the cuboid defined by gae < 3.8 × 10−12, ..., and gaegaγ < 7.7 × 10−22 GeV−1, and excludes either gae = 0 or ... . The neutrino magnetic moment signal is similarly favored over background at 3.2σ, and a confidence interval of μν ∈ (1.4, 2.9) × 10−11 μB (90% C.L.) is reported. Both results are in strong tension with stellar constraints. The excess can also be explained by β decays of tritium at 3.2σ significance with a corresponding tritium concentration in xenon of (6.2 ± 2.0) × 10−25 mol/mol. Such a trace amount can neither be confirmed nor excluded with current knowledge of its production and reduction mechanisms. The significances of the solar axion and neutrino magnetic moment hypotheses are decreased to 2.0σ and 0.9σ, respectively, if an unconstrained tritium component is included in the fitting. With respect to bosonic dark matter, the excess favors a monoenergetic peak at (2.3 ± 0.2) keV (68% C.L.) with a 3.0σ global (4.0σ local) significance over background. This analysis sets the most restrictive direct constraints to date on pseudoscalar and vector bosonic dark matter for most masses between 1 and 210 keV/c2. We also consider the possibility that 37Ar may be present in the detector, yielding a 2.82 keV peak from electron capture. Contrary to tritium, the 37Ar concentration can be tightly constrained and is found to be negligible. (ProQuest: ... denotes formula omitted.)
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
We report constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment. We mitigate backgrounds with strong event selections, rather than requiring a scintillation ...signal, leaving an effective exposure of (22±3) tonne day. Above ∼0.4 keV_{ee}, we observe <1 event/(tonne day keV_{ee}), which is more than 1000 times lower than in similar searches with other detectors. Despite observing a higher rate at lower energies, no DM or CEvNS detection may be claimed because we cannot model all of our backgrounds. We thus exclude new regions in the parameter spaces for DM-nucleus scattering for DM masses m_{χ} within 3-6 GeV/c^{2}, DM-electron scattering for m_{χ}>30 MeV/c^{2}, and absorption of dark photons and axionlike particles for m_{χ} within 0.186-1 keV/c^{2}.
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A global assessment of precipitation chemistry and deposition has been carried out under the direction of the World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) Scientific Advisory ...Group for Precipitation Chemistry (SAG-PC). The assessment addressed three questions: (1) what do measurements and model estimates of precipitation chemistry and wet, dry and total deposition of sulfur, nitrogen, sea salt, base cations, organic acids, acidity, and phosphorus show globally and regionally? (2) has the wet deposition of major ions changed since 2000 (and, where information and data are available, since 1990) and (3) what are the major gaps and uncertainties in our knowledge? To that end, regionally-representative measurements for two 3-year-averaging periods, 2000–2002 and 2005–2007, were compiled worldwide. Data from the 2000–2002 averaging period were combined with 2001 ensemble-mean modeling results from 21 global chemical transport models produced in Phase 1 of the Coordinated Model Studies Activities of the Task Force on Hemispheric Transport of Air Pollution (TF HTAP). The measurement data and modeling results were used to generate global and regional maps of major ion concentrations in precipitation and deposition. A major product of the assessment is a database of quality assured ion concentration and wet deposition data gathered from regional and national monitoring networks. The database is available for download from the World Data Centre for Precipitation Chemistry (http://wdcpc.org/). The assessment concludes that global concentrations and deposition of sulfur and nitrogen are reasonably well characterized with levels generally highest near emission sources and more than an order of magnitude lower in areas largely free of anthropogenic influences. In many parts of the world, wet deposition of reduced nitrogen exceeds that of oxidized nitrogen and is increasing. Sulfur and nitrogen concentrations and deposition in North America and Europe have declined significantly in line with emission reduction policies. Major regions of the world, including South America, the more remote areas of North America, much of Asia, Africa, Oceania, polar regions, and all of the oceans, are inadequately sampled for all of the major ions in wet and dry deposition, and particularly so for phosphorus, organic forms of nitrogen, and weak acids including carbonates and organic acids. Measurement-based inferential estimates of dry deposition are limited to sulfur and some nitrogen in only a few regions of the world and methods are highly uncertain. The assessment concludes with recommendations to address major gaps and uncertainties in global ion concentration and deposition measurements.
•Assessed the global distribution of precipitation composition and deposition of major ions.•Produced a global data set of quality assured wet deposition monitoring data for 2000–2002 and 2005–2007.•Generated global wet deposition maps of major ions combining measurement and modeling results.•Established that sulfur and nitrogen wet deposition is highest in parts of Asia, Europe and eastern North America.•Determined that major gaps in wet and dry deposition monitoring exist globally.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We report the first experimental results on spin-dependent elastic weakly interacting massive particle (WIMP) nucleon scattering from the XENON1T dark matter search experiment. The analysis uses the ...full ton year exposure of XENON1T to constrain the spin-dependent proton-only and neutron-only cases. No significant signal excess is observed, and a profile likelihood ratio analysis is used to set exclusion limits on the WIMP-nucleon interactions. This includes the most stringent constraint to date on the WIMP-neutron cross section, with a minimum of 6.3×10^{-42} cm^{2} at 30 GeV/c^{2} and 90% confidence level. The results are compared with those from collider searches and used to exclude new parameter space in an isoscalar theory with an axial-vector mediator.
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The event formalism is a nonlinear extension of quantum field theory designed to be compatible with the closed time-like curves that appear in general relativity. Whilst reducing to standard quantum ...field theory in flat space-time the formalism leads to testably different predictions for entanglement distribution in curved space. In this paper we introduce a more general version of the formalism and use it to analyse the practicality of an experimental test of its predictions in the Earthʼs gravitational well.
Massive urbanization and increasing disposable incomes favor a rapid transition in diets and lifestyle in sub-Saharan Africa (SSA). As a result, the SSA population is becoming increasingly vulnerable ...to the double burden of malnutrition and obesity. This, combined with the increasing pressure to produce sufficient food and provide employment for this growing population together with the threat of climate change-induced declining crop yields, requires urgent sustainable solutions. Can an increase in the cultivation of climate-resilient crops (CRCs) and their utilization to produce attractive, convenient and nutritious bread products contribute to climate change adaptation and healthy and sustainable diets? A food system analysis of the bread food value chain in SSA indicates that replacement of refined, mostly imported, wheat in attractive bread products could (1) improve food and nutrition security, (2) bring about a shift to more nutritionally balanced diets, (3) increase economic inclusiveness and equitable benefits, and (4) improve sustainability and resilience of the food system. The food system analysis also provided systematic insight into the challenges and hurdles that need to be overcome to increase the availability, affordability and uptake of CRCs. Proposed interventions include improving the agronomic yield of CRCs, food product technology, raising consumer awareness and directing policies. Overall, integrated programs involving all stakeholders in the food system are needed.
South Africa is the economic hub of southern Africa and is regarded as an important source region of atmospheric pollutants. A nitrogen dioxide (NO2) hotspot is clearly visible from space over the ...South African Mpumalanga Highveld, while South Africa is also regarded as the 9th largest anthropogenic sulphur (S) emitting country. Notwithstanding the importance of South Africa with regard to nitrogen (N) and S emissions, very limited data has been published on the chemical composition of wet deposition for this region. This paper presents the concentrations of sodium (Na+), ammonium (NH4+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), nitrate (NO3−), chloride (Cl−), sulphate (SO42−) and water-soluble organic acids (OA) in the wet deposition samples collected between 2009 and 2014 at four South African IDAF (IGAC DEBITS Africa) sites, which are regarded as regional representatives of the north-eastern interior. Also, wet deposition fluxes of the ten ions are calculated and presented in this paper. The results show that the total ionic concentrations and fluxes of wet deposition were much higher at the two sites closer to anthropogenic emissions, while the pH of wet deposition at these two sites were lower compared to that of the two sites that were less impacted by anthropogenic emissions. . The major sources of the ten ions included marine, terrigenous (crust), fossil fuel combustion, agriculture and biomass burning. Significant contributions from fossil fuel combustion were determined for the two sites in close proximity to anthropogenic source regions. The results of back trajectory analysis, however, did indicate that the two remote sites are also affected by air masses passing over the source region through anti-cyclonic recirculation. The largest contributions at the two sites distant from the anthropogenic source regions were marine sources, while the impact of biomass burning was also more significant at the remote sites. Comparison to previous wet deposition measurements at the South African IDAF sites indicated increases in the wet deposition fluxes of S and N, and more wet deposition events with lower pH. This could be ascribed to a significant increase in anthropogenic activities and population growth in this part of South Africa with an associated increase in energy demand.
•Significant impacts of anthropogenic activities on rain chemistry are indicated.•Contributions from marine and crustal sources are reflected in rain chemistry.•More rainfall events with low pH occur at sites nearby anthropogenic sources.•Increased S- and N-deposition, and rain events with lower pH from 1984 to 2014.•Rainfall chemistry reflects increased anthropogenic sources and population growth.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
BackgroundChronic kidney disease (CKD) is one of the major health issues in Pakistan, exerting notable effects on both the physical and mental well-being of individuals undergoing haemodialysis. Of ...particular concern to healthcare professionals is the potential adverse influence of haemodialysis on the lives of patients with CKD residing in rural areas of the country. This study will explore and describe the lived experiences and needs of patients with CKD receiving haemodialysis from the perspectives of patients and their family caregivers.Methods and analysisTranscendental phenomenological research design will be used. Participants will be recruited from the dialysis centre of a tertiary hospital through purposive sampling based on specific inclusion criteria. In-depth unstructured interviews, observation and document analysis will be the methods for data collection. Data will be analysed using Colaizzi’s approach following the transcription of the interviews.Ethics and disseminationThe study has been approved by the Institutional Review Board (IRB) of Shifa Tameer-e-Millat University, Pakistan (IRB # 0307–23) and written permission was obtained from the administration of the study hospital. Before giving written and verbal consent, all participants will receive detailed information about the study. Participants will maintain the freedom to withdraw from the study at any point. Confidentiality of the participants will be ensured. The study findings will be disseminated to important stakeholders and published in scientific papers and conference proceedings.
South Africa is considered an important source region of
atmospheric pollutants, which is compounded by high population and
industrial growth. However, this region is understudied, especially with
...regard to evaluating long-term trends of atmospheric pollutants. The aim of
this study was to perform statistical modelling of SO2, NO2 and
O3 long-term trends based on 21-, 19- and 16-year passive sampling
datasets available for three South African INDAAF (International Network to study Deposition and Atmospheric Chemistry
in Africa) sites located within
proximity of the pollution hotspot in the industrialized north-eastern
interior in South Africa. The interdependencies between local, regional and
global parameters on variances in SO2, NO2 and O3 levels were
investigated in the model. Average monthly SO2 concentrations at
Amersfoort (AF), Louis Trichardt (LT) and Skukuza (SK) were 9.91, 1.70 and 2.07 µg m−3, respectively,
while respective mean monthly NO2 concentrations at each of these sites
were 6.56, 1.46 and 2.54 µg m−3. Average monthly O3 concentrations were 50.77, 58.44 and 43.36 µg m−3 at AF, LT and
SK, respectively. Long-term temporal trends indicated seasonal and
inter-annual variability at all three sites, which could be ascribed to
changes in meteorological conditions and/or variances in source
contribution. Local, regional and global parameters contributed to SO2
variability, with total solar irradiation (TSI) being the most significant
factor at the regional background site LT. Temperature (T) was the most
important factor at SK, located in the Kruger National Park, while
population growth (P) made the most substantial contribution at the
industrially impacted AF site. Air masses passing over the source region
also contributed to SO2 levels at SK and LT. Local and regional factors
made more substantial contributions to modelled NO2 levels, with P
being the most significant factor explaining NO2 variability at all
three sites, while relative humidity (RH) was the most important local and
regional meteorological factor. The important contribution of P on modelled
SO2 and NO2 concentrations was indicative of the impact of
increased anthropogenic activities and energy demand in the north-eastern
interior of South Africa. Higher SO2 concentrations, associated with
lower temperatures, as well as the negative correlation of NO2 levels
to RH, reflected the influence of pollution build-up and increased household
combustion during winter. The El Niño–Southern Oscillation (ENSO) made a
significant contribution to modelled O3 levels at all three sites,
while the influence of local and regional meteorological factors was also
evident. Trend lines for SO2 and NO2 at AF indicated an increase
in SO2 and NO2 concentrations over the 19-year sampling period,
while an upward trend in NO2 levels at SK signified the influence of
growing rural communities. Marginal trends were observed for SO2 at SK,
as well as SO2 and NO2 at LT, while O3 remained relatively
constant at all three sites. SO2 and NO2 concentrations were
higher at AF, while the regional O3 problem was evident at all three
sites.
This study presents a total of four years of sub-micron aerosol particle size distribution measurements in the southern African savannah, an environment with few previous observations covering a full ...seasonal cycle and the size range below 100 nm. During the first 19 months, July 2006-January 2008, the measurements were carried out at Botsalano, a semi-clean location, whereas during the latter part, February 2008-May 2010, the measurements were carried out at Marikana (approximately 150 km east of Botsalano), which is a more polluted location with both pyrometallurgical industries and informal settlements nearby. The median total concentration of aerosol particles was more than four times as high at Marikana than at Botsalano. In the size ranges of 12-840 nm, 50-840 nm and 100-840 nm the median concentrations were 1856, 1278 and 698 particles cm super(-3) at Botsalano and 7805, 3843 and 1634 particles cm super(-3) at Marikana, respectively. The diurnal variation of the size distribution for Botsalano arose as a result of frequent regional new particle formation. However, for Marikana the diurnal variation was dominated by the morning and evening household burning in the informal settlements, although regional new particle formation was even more frequent than at Botsalano. The effect of the industrial emissions was not discernible in the size distribution at Marikana although it was clear in the sulphur dioxide diurnal pattern, indicating the emissions to be mostly gaseous. Seasonal variation was strongest in the concentration of particles larger than 100 nm, which was clearly elevated at both locations during the dry season from May to September. In the absence of wet removal during the dry season, the concentration of particles larger than 100 nm had a correlation above 0.7 with CO for both locations, which implies incomplete burning to be an important source of aerosol particles during the dry season. However, the sources of burning differ: at Botsalano the rise in concentration originates from regional wild fires, while at Marikana domestic heating in the informal settlements is the main source. Air mass history analysis for Botsalano identified four regional scale source areas in southern Africa and enabled the differentiation between fresh and aged rural background aerosol originating from the clean sector, i.e., western sector with very few large anthropogenic sources. Comparison to size distributions published for other comparable environments in Northern Hemisphere shows southern African savannah to have a unique combination of sources and meteorological parameters. The observed strong link between combustion and seasonal variation is comparable only to the Amazon basin; however, the lack of long-term observations in the Amazonas does not allow a quantitative comparison. All the data presented in the figures, as well as the time series of monthly mean and median size distributions are included in numeric form as a Supplement to provide a reference point for the aerosol modelling community.
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