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Träfflista för sökning "WFRF:(Shekhar M) "

Sökning: WFRF:(Shekhar M)

  • Resultat 1-10 av 14
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2.
  • Aaltonen, T., et al. (författare)
  • Combination of CDF and D0 W-Boson mass measurements
  • 2013
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 88:5, s. 052018-
  • Tidskriftsartikel (refereegranskat)abstract
    • We summarize and combine direct measurements of the mass of the W boson in root s = 1.96 TeV proton-antiproton collision data collected by CDF and D0 experiments at the Fermilab Tevatron Collider. Earlier measurements from CDF and D0 are combined with the two latest, more precise measurements: a CDF measurement in the electron and muon channels using data corresponding to 2.2 fb(-1) of integrated luminosity, and a D0 measurement in the electron channel using data corresponding to 4.3 fb(-1) of integrated luminosity. The resulting Tevatron average for the mass of the W boson is M-W = 80387 +/- 16 MeV. Including measurements obtained in electron-positron collisions at LEP yields the most precise value of M-W = 80385 +/- 15 MeV.
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4.
  • Jansen, Joachim, 1989-, et al. (författare)
  • Monitoring of carbon-water fluxes at Eurasian meteorological stations using random forest and remote sensing
  • 2023
  • Ingår i: Scientific Data. - : Springer Nature. - 2052-4463. ; 10:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Simulating the carbon-water fluxes at more widely distributed meteorological stations based on the sparsely and unevenly distributed eddy covariance flux stations is needed to accurately understand the carbon-water cycle of terrestrial ecosystems. We established a new framework consisting of machine learning, determination coefficient (R2), Euclidean distance, and remote sensing (RS), to simulate the daily net ecosystem carbon dioxide exchange (NEE) and water flux (WF) of the Eurasian meteorological stations using a random forest model or/and RS. The daily NEE and WF datasets with RS-based information (NEE-RS and WF-RS) for 3774 and 4427 meteorological stations during 2002-2020 were produced, respectively. And the daily NEE and WF datasets without RS-based information (NEE-WRS and WF-WRS) for 4667 and 6763 meteorological stations during 1983-2018 were generated, respectively. For each meteorological station, the carbon-water fluxes meet accuracy requirements and have quasi-observational properties. These four carbon-water flux datasets have great potential to improve the assessments of the ecosystem carbon-water dynamics.
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5.
  • Rahnev, D, et al. (författare)
  • The Confidence Database
  • 2020
  • Ingår i: Nature human behaviour. - : Springer Science and Business Media LLC. - 2397-3374. ; 4:3, s. 317-325
  • Tidskriftsartikel (refereegranskat)
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6.
  • Galbany, L., et al. (författare)
  • Evidence for a Chandrasekhar-mass explosion in the Ca-strong 1991bg-like type la supernova 2016hnk
  • 2019
  • Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 630
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims. We present a comprehensive dataset of optical and near-infrared photometry and spectroscopy of type Ia supernova (SN) 2016hnk, combined with integral field spectroscopy (IFS) of its host galaxy, MCG -01-06-070, and nearby environment. Our goal with this complete dataset is to understand the nature of this peculiar object.Methods. Properties of the SN local environment are characterized by means of single stellar population synthesis applied to IFS observations taken two years after the SN exploded. We performed detailed analyses of SN photometric data by studying its peculiar light and color curves. SN 2016hnk spectra were compared to other 1991bg-like SNe Ia, 2002es-like SNe Ia, and Ca-rich transients. In addition, we used abundance stratification modeling to identify the various spectral features in the early phase spectral sequence and also compared the dataset to a modified non-LTE model previously produced for the sublumnious SN 1999by.Results. SN 2016hnk is consistent with being a subluminous (M-B = -16.7 mag, S-BV =0.43 +/- 0.03), highly reddened object. The IFS of its host galaxy reveals both a significant amount of dust at the SN location, residual star formation, and a high proportion of old stellar populations in the local environment compared to other locations in the galaxy, which favors an old progenitor for SN 2016hnk. Inspection of a nebular spectrum obtained one year after maximum contains two narrow emission lines attributed to the forbidden [Ca II] lambda lambda 7291,7324 doublet with a Doppler shift of 700 km s(-1). Based on various observational diagnostics, we argue that the progenitor of SN 2016hnk was likely a near Chandrasekhar-mass (M-Ch) carbon-oxygen white dwarf that produced 0.108 M-circle dot of Ni-56. Our modeling suggests that the narrow [Ca II] features observed in the nebular spectrum are associated with Ca-48 from electron capture during the explosion, which is expected to occur only in white dwarfs that explode near or at the M-Ch limit.
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8.
  • Belopolski, Ilya, et al. (författare)
  • Observation of a linked-loop quantum state in a topological magnet
  • 2022
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 604:7907, s. 647-652
  • Tidskriftsartikel (refereegranskat)abstract
    • Quantum phases can be classified by topological invariants, which take on discrete values capturing global information about the quantum state1–13. Over the past decades, these invariants have come to play a central role in describing matter, providing the foundation for understanding superfluids5, magnets6,7, the quantum Hall effect3,8, topological insulators9,10, Weyl semimetals11–13 and other phenomena. Here we report an unusual linking-number (knot theory) invariant associated with loops of electronic band crossings in a mirror-symmetric ferromagnet14–20. Using state-of-the-art spectroscopic methods, we directly observe three intertwined degeneracy loops in the material’s three-torus, T3, bulk Brillouin zone. We find that each loop links each other loop twice. Through systematic spectroscopic investigation of this linked-loop quantum state, we explicitly draw its link diagram and conclude, in analogy with knot theory, that it exhibits the linking number (2, 2, 2), providing a direct determination of the invariant structure from the experimental data. We further predict and observe, on the surface of our samples, Seifert boundary states protected by the bulk linked loops, suggestive of a remarkable Seifert bulk–boundary correspondence. Our observation of a quantum loop link motivates the application of knot theory to the exploration of magnetic and superconducting quantum matter.
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9.
  • Krieger, Jonas A., et al. (författare)
  • Weyl spin-momentum locking in a chiral topological semimetal
  • 2024
  • Ingår i: Nature Communications. - 2041-1723. ; 15:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Spin-orbit coupling in noncentrosymmetric crystals leads to spin-momentum locking – a directional relationship between an electron’s spin angular momentum and its linear momentum. Isotropic orthogonal Rashba spin-momentum locking has been studied for decades, while its counterpart, isotropic parallel Weyl spin-momentum locking has remained elusive in experiments. Theory predicts that Weyl spin-momentum locking can only be realized in structurally chiral cubic crystals in the vicinity of Kramers-Weyl or multifold fermions. Here, we use spin- and angle-resolved photoemission spectroscopy to evidence Weyl spin-momentum locking of multifold fermions in the chiral topological semimetal PtGa. We find that the electron spin of the Fermi arc surface states is orthogonal to their Fermi surface contour for momenta close to the projection of the bulk multifold fermion at the Γ point, which is consistent with Weyl spin-momentum locking of the latter. The direct measurement of the bulk spin texture of the multifold fermion at the R point also displays Weyl spin-momentum locking. The discovery of Weyl spin-momentum locking may lead to energy-efficient memory devices and Josephson diodes based on chiral topological semimetals.
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10.
  • Ali, S., et al. (författare)
  • Concentration of fluoride in groundwater of India : A systematic review, meta-analysis and risk assessment
  • 2019
  • Ingår i: Groundwater for Sustainable Development. - : Elsevier. - 2352-801X. ; 9
  • Forskningsöversikt (refereegranskat)abstract
    • It is a well-known fact that the Indian groundwater is polluted by fluoride. However, for the first time in India, non-carcinogenic risk assessments and meta-analysis of fluoride exposure to humans were carried out due to consumption of groundwater. In this context, we collected fluoride concentration data in groundwater across India by systematic searches conducted in various international search engines databases. Here, we demonstrated a detailed meta-analysis and meta-regression of fluoride and evaluated health risk assessment. For this purpose, meta-analysis of 63 studies on fluoride in groundwater in India, comprising 57381 samples are included. We found that 1.) The pooled concentration of fluoride in India is around 2.37 mg/L with 95% confident interval (1.46–3.28 mg/L) which is higher than WHO and national standards limit of 1.5 mg/L. 2) The meta-analysis of data suggests that in rural parts of the country, fluoride concentration is 1.85 times higher than urban areas. 3) The concentration of fluoride in groundwater decreased significantly (p < 0.05) with increase in rainfall and longitude. The risk assessment via oral and dermal route exposure reveals that the consumers in majority of the regions are at considerable non-carcinogenic risk and children are at higher risk than adults (Total hazard quotient > 1). The findings are helpful in identifying the affected areas of India and we recommend that the safer options of drinking water should be adopted.
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