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- 2017
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:2
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Tidskriftsartikel (refereegranskat)
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| 11. |
- Barausse, Enrico, et al.
(författare)
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Prospects for fundamental physics with LISA
- 2020
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Ingår i: General Relativity and Gravitation. - : SPRINGER/PLENUM PUBLISHERS. - 0001-7701 .- 1572-9532. ; 52:8
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, which is of programmatic rather than quantitative nature, we aim to further delineate and sharpen the future potential of the LISA mission in the area of fundamental physics. Given the very broad range of topics that might be relevant to LISA,we present here a sample of what we view as particularly promising fundamental physics directions. We organize these directions through a "science-first" approach that allows us to classify how LISA data can inform theoretical physics in a variety of areas. For each of these theoretical physics classes, we identify the sources that are currently expected to provide the principal contribution to our knowledge, and the areas that need further development. The classification presented here should not be thought of as cast in stone, but rather as a fluid framework that is amenable to change with the flow of new insights in theoretical physics.
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| 12. |
- Arun, K. G., et al.
(författare)
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New horizons for fundamental physics with LISA
- 2022
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Ingår i: Living Reviews in Relativity. - : Springer Science and Business Media LLC. - 1433-8351 .- 2367-3613. ; 25:1
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Forskningsöversikt (refereegranskat)abstract
- The Laser Interferometer Space Antenna (LISA) has the potential to reveal wonders about the fundamental theory of nature at play in the extreme gravity regime, where the gravitational interaction is both strong and dynamical. In this white paper, the Fundamental Physics Working Group of the LISA Consortium summarizes the current topics in fundamental physics where LISA observations of gravitational waves can be expected to provide key input. We provide the briefest of reviews to then delineate avenues for future research directions and to discuss connections between this working group, other working groups and the consortium work package teams. These connections must be developed for LISA to live up to its science potential in these areas.
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| 13. |
- Bhagwat, A., et al.
(författare)
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Microscopic-Macroscopic Mass Calculations with Wigner-Kirkwood expansion
- 2011
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Ingår i: International EFES-IN2P3 Conference on "Many Body Correlations from Dilute to Dense Nuclear Systems", MBC 2011. - : IOP Publishing. - 1742-6588. ; 321:1, s. 012053-
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Tidskriftsartikel (refereegranskat)abstract
- The systematic study and calculation of ground state nuclear masses continues to be one of the active and important areas of research in nuclear physics. The present work is an attempt to determine the ground state masses of nuclei spanning the entire periodic table, using the Microscopic-Macroscopic approach. The semi-classical Wigner-Kirkwood (WK) expansion method is used to calculate shell corrections for spherical and deformed nuclei. The expansion is achieved upto the fourth order in . The shell corrections, along with the pairing energies obtained by using the Lipkin-Nogami scheme, constitute the microscopic part of the nuclear masses. The macroscopic part is obtained from a liquid drop formula with six adjustable parameters. It is shown that the Microscopic-Macroscopic mass calculation thus achieved, yields reliable description of ground state masses of nuclei across the periodic table. The present status of the WK mass calculations and the possible future perspectives are discussed.
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| 14. |
- Prasad, Bhagwat, et al.
(författare)
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Toward a Consensus on Applying Quantitative Liquid Chromatography-Tandem Mass Spectrometry Proteomics in Translational Pharmacology Research : A White Paper
- 2019
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Ingår i: Clinical Pharmacology and Therapeutics. - : WILEY. - 0009-9236 .- 1532-6535. ; 106:3, s. 525-543
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Tidskriftsartikel (refereegranskat)abstract
- Quantitative translation of information on drug absorption, disposition, receptor engagement, and drug-drug interactions from bench to bedside requires models informed by physiological parameters that link in vitro studies to in vivo outcomes. To predict in vivo outcomes, biochemical data from experimental systems are routinely scaled using protein quantity in these systems and relevant tissues. Although several laboratories have generated useful quantitative proteomic data using state-of-the-art mass spectrometry, no harmonized guidelines exit for sample analysis and data integration to in vivo translation practices. To address this gap, a workshop was held on September 27 and 28, 2018, in Cambridge, MA, with 100 experts attending from academia, the pharmaceutical industry, and regulators. Various aspects of quantitative proteomics and its applications in translational pharmacology were debated. A summary of discussions and best practices identified by this expert panel are presented in this "White Paper" alongside unresolved issues that were outlined for future debates.
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| 15. |
- Bennett, Keith D., et al.
(författare)
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Neotropical refugia
- 2012
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Ingår i: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 22:11, s. 1207-1214
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Tidskriftsartikel (refereegranskat)abstract
- Patterns of endemism in the Neotropics have been explained by restriction of forest to 'refugia' in arid cold-stages of the Quaternary (Haffer J (1969) Speciation in Amazonian forest birds. Science 165: 131-137). The palaeoecological record, however, shows no such forest contraction. We review palaeoecological and phylogenetic data on the response of Neotropical taxa and communities to climatic changes of the Cenozoic. Solar insolation varies over this period with latitude and geography, including shifts in opposite directions between high and low latitudes. In the Neotropics, distribution and abundance patterns originate on a wide range of timescales through the Cenozoic, down to the currently dominant precession forcing (20 kyr). In contrast, distributions and abundances at higher latitudes are controlled by obliquity forcing (40 kyr). The patterns observed by Haffer (1969) are likely derived from pre-Quaternary radiations and are not inconsistent with palaeoecological findings of continuous forest cover in major areas of the Neotropics during the Quaternary. The relative proportions of speciation processes have changed through time between predominantly sympatric to predominantly allopatric depending on the prevailing characteristics of orbitally forced climatic changes. Behaviour of Neotropical organisms and ecosystems on long timescales may be influenced much more by precessional forcing than by the obliquity forcing that controls high-latitude climate change and glaciations.
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| 16. |
- Bhagwat, A., et al.
(författare)
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Cluster emission from superheavy nuclei
- 2018
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Ingår i: European Physical Journal A. - : SPRINGER. - 1434-6001 .- 1434-601X. ; 54:11
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Tidskriftsartikel (refereegranskat)abstract
- The process leading to cluster emission from superheavy nuclei in the range 100 122 has been systematically investigated. This topic is of importance because it opens up the possibility of identifying superheavy elements through deposition of clusters in the detection system. In this paper we evaluate the cluster decay half lives by considering the cluster as a particle. The motion of this particle in the field induced by the daughter nucleus is determined by solving the corresponding Schrodinger equation imposing outgoing boundary conditions (Gamow state). The corresponding Wood-Saxon potential is fitted to obtain the energies provided by a mass formula that has been established recently to have a very high degree of precision. The resulting expression for the decay width is exact, i.e. no approximation besides the assumption of a preformed cluster is introduced. It is found that the heavy cluster emission probability in the superheavy region is much smaller than the corresponding a emission probability.
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| 17. |
- Bhagwat, A., et al.
(författare)
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Investigation of band termination in the lower fp shell within the cranked relativistic mean field model
- 2013
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Ingår i: International Conference on Recent Trends in Nuclear Physics-2012 (ICRTNP 2012). - : AIP. - 9780735411470 ; , s. 105-108
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Konferensbidrag (refereegranskat)abstract
- The excitation energy difference (ΔE) between the terminating states built on the f7/2 n and d3/2 -1f 7/2 n+1 configurations (here, 'n' denotes the number of valence particles outside the 40Ca core and the particle hole excitation across the magic gap 20 is of proton type) in the lower fp shell are studied systematically within the framework of the cranked relativistic mean field model. The ΔE thus defined, depends predominantly on the f 7/2 - d3/2 shell gap, and its evolution as a function of neutron - proton asymmetry. The latter, in turn, depends on the isoscalar - isovector balance in the spin - orbit potential. Therefore, a systematic investigation of the difference ΔE is expected to test quantitatively the predicted shell gaps as a function of isospin. We find that: 1) the conventional NL3 parameter set over estimates the ΔE values, implying that the said shell gap is over - estimated in this parametrization and 2) the largest deviation between the calculated and the experimental values of ΔE is obtained for the nucleus with the smallest asymmetry value in the set of nuclei considered, and that the deviation decreases with increasing asymmetry, indicating that the in RMF parametrization considered, the isoscalar - isovector balance in the spin - orbit potential requires improvement. We carry out a re - fit of the RMF parameters to attempt a remedy to these two problems. We find that in addition to the binding energies and charge radii, if a constraint is put on the f7/2 - d3/2 shell gap in the fit to the Lagrangian parameters, the overall agreement of ΔE with the experiment improves significantly, without disturbing the agreement already achieved for the bulk properties of the nuclei spanning the entire periodic table. At a finer level, however, it is found that the isoscalar - isovector balance in the spin orbit interaction is required to be improved further. A detailed work in this direction is in progress.
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| 18. |
- Bhagwat, A., et al.
(författare)
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Mic–Mac model based on the Wigner–Kirkwood method
- 2023
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Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 59:12
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Tidskriftsartikel (refereegranskat)abstract
- About a decade ago we proposed a new Microscopic–Macroscopic (Mic–Mac) model where the semiclassical Wigner–Kirkwood expansion of the energy up to fourth-order in ħ is used to compute the shell corrections in a deformed Woods-Saxon potential instead of the usual Strutinsky averaging scheme [1, 2]. For a set of 551 even-even nuclei computed with this new model, we found a rms deviation of 610 keV from the experimental masses, similar to the value obtained using the well-known Finite Range Droplet Model and the Lublin–Strasbourg Drop Model for the same set of nuclei. In a next step, we compute the ground-state properties of these 551 nuclei with the same method but using the mean-field provided by the Gogny forces within an Extended Thomas-Fermi approximation. We find that this Mic–Mac model using the Gogny D1S (D1M) force gives a fairly good description of the ground-state energies with a rms deviation of 834 keV (819 keV). This implies that Mic–Mac models based on effective two-body forces, for example Gogny D1S and D1M interactions, perform practically as well as the most efficient Mic–Mac models regarding ground-state properties.
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| 19. |
- Bhagwat, A., et al.
(författare)
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Microscopic-macroscopic approach for binding energies with the Wigner-Kirkwood method. II. Deformed nuclei
- 2012
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 86:4, s. 044316-
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Tidskriftsartikel (refereegranskat)abstract
- The binding energies of deformed even-even nuclei have been analyzed within the framework of a recently proposed microscopic-macroscopic model. We have used the semiclassical Wigner-Kirkwood (h) over bar expansion up to fourth order, instead of the usual Strutinsky averaging scheme, to compute the shell corrections in a deformed Woods-Saxon potential including the spin-orbit contribution. For a large set of 561 even-even nuclei with Z >= 8 and N >= 8, we find an rms deviation from the experiment of 610 keV in binding energies, comparable to the one found for the same set of nuclei using the finite range droplet model of Moller and Nix (656 keV). As applications of our model, we explore its predictive power near the proton and neutron drip lines as well as in the superheavy mass region. Next, we systematically explore the fourth-order Wigner-Kirkwood corrections to the smooth part of the energy. It is found that the ratio of the fourth-order to the second-order corrections behaves in a very regular manner as a function of the asymmetry parameter I = (N - Z)/A. This allows us to absorb the fourth-order corrections into the second-order contributions to the binding energy, which enables us to simplify and speed up the calculation of deformed nuclei.
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| 20. |
- Bhagwat, A., et al.
(författare)
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Recent developments in the Wigner - Kirkwood mass formula
- 2013
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Ingår i: International Conference on Recent Trends in Nuclear Physics-2012 (ICRTNP-2012). - : AIP. - 9780735411470 ; , s. 20-24
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Konferensbidrag (refereegranskat)abstract
- The recently proposed microscopic - macroscopic model for nuclear masses, based on the shell corrections obtained by using the semi - classical Wigner - Kirkwood (WK) ℏ expansion of one body quantal partition function, has been extended to the even - even deformed nuclei. The nuclear potential is assumed to be deformed Woods - Saxon with spin - orbit contribution. The Coulomb potential is obtained by folding charge densities. The resulting partition function is expanded upto the fourth order in ℏ to obtain averaged energies. The shell corrections thus obtained along with pairing energies determined within the framework of the Lipkin - Nogami scheme constitute microscopic part of the model. The macroscopic part is obtained from a liquid drop formula, with nine adjustable parameters. These parameters are fitted by considering a large set of 561 even - even nuclei with Z ≥ 8 and N ≥ 8. The fit yields rms deviation of merely 610 keV from the corresponding experimental masses. A few applications of the mass formula are presented and discussed in this paper.
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| 21. |
- Bhagwat, A., et al.
(författare)
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WIGNER-KIRKWOOD METHOD FOR MICROSCOPIC-MACROSCOPIC CALCULATION OF BINDING ENERGIES
- 2010
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Ingår i: International Journal of Modern Physics E. - 0218-3013. ; 19:4, s. 747-758
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Tidskriftsartikel (refereegranskat)abstract
- We propose to use the semi-classical Wigner-Kirkwood (h) over bar expansion to calculate shell corrections for spherical and deformed nuclei. The expansion is carried out up to fourth order in (h) over bar. A systematic study of Wigner-Kirkwood averaged energies is presented as a function of the deformation degrees of freedom. The shell corrections, along with the pairing energies obtained by using the Lipkin-Nogami scheme are used in the microscopic-macroscopic approach to calculate binding energies. The macroscopic part is obtained from a liquid drop formula with six adjustable parameters. Considering a set of 367 spherical nuclei, the liquid drop parameters are adjusted to reproduce the experimental binding energies, which yields a rms deviation of 630 keV.
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| 22. |
- Vinas, X., et al.
(författare)
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Applications to nuclear properties of the microscopic-macroscopic model based on the semiclassical Wigner-Kirkwood method
- 2015
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Ingår i: Physica Scripta. - : Institute of Physics Publishing (IOPP). - 0031-8949 .- 1402-4896. ; 90:11
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Tidskriftsartikel (refereegranskat)abstract
- Some time ago we proposed a new microscopic-macroscopic model where the semiclassical Wigner-Kirkwood expansion of the energy up to fourth-order in. is used to compute the shell corrections in a deformed Woods-Saxon potential instead of the usual Strutinsky averaging scheme. For a set of 558 even-even nuclei computed with this new model, we found a rms deviation of 610 keV from the experimental masses, similar to the value obtained using the well-known finite range droplet model and the Lublin-Strasbourg drop model for the same set of nuclei. In this paper we analyze the alpha radioactivity in nuclei with mass number A similar to 100, finding good agreement with the available experimental results. We have also estimated spontaneous fission half-lives for superheavy nuclei in the region between Z = 102 and Z = 110. We find that our model predicts reasonably well the experimental half-lives in the considered nuclei, in spite of the fact that the fission barriers turn out to be somewhat too high.
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| 23. |
- Willis, Kathy J., et al.
(författare)
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4 degrees C and beyond: what did this mean for biodiversity in the past?
- 2010
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Ingår i: Systematics and Biodiversity. - : Informa UK Limited. - 1477-2000 .- 1478-0933. ; 8, s. 3-9
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Tidskriftsartikel (refereegranskat)abstract
- How do the predicted climatic changes (IPCC, 2007) for the next century compare in magnitude and rate to those that Earth has previously encountered? Are there comparable intervals of rapid rates of temperature change, sea-level rise and levels of atmospheric CO2 that can be used as analogues to assess possible biotic responses to future change? Or are we stepping into the great unknown? This perspective article focuses on intervals in time in the fossil record when atmospheric CO2 concentrations increased up to 1200 ppmv, temperatures in mid-to high-latitudes increased by greater than 4 degrees C within 60 years, and sea levels rose by up to 3 m higher than present. For these intervals in time, case studies of past biotic responses are presented to demonstrate the scale and impact of the magnitude and rate of such climate changes on biodiversity. We argue that although the underlying mechanisms responsible for these past changes in climate were very different (i.e. natural processes rather than anthropogenic), the rates and magnitude of climate change are similar to those predicted for the future and therefore potentially relevant to understanding future biotic response. What emerges from these past records is evidence for rapid community turnover, migrations, development of novel ecosystems and thresholds from one stable ecosystem state to another, but there is very little evidence for broad-scale extinctions due to a warming world. Based on this evidence from the fossil record, we make four recommendations for future climate-change integrated conservation strategies.
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