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Full-Text Articles in Physical Sciences and Mathematics
Optimal Ranking Regime Analysis Of Intra- To Multidecadal U.S. Climate Variability. Part I: Temperature, Eugene C. Cordero, Steven A. Mauget
Optimal Ranking Regime Analysis Of Intra- To Multidecadal U.S. Climate Variability. Part I: Temperature, Eugene C. Cordero, Steven A. Mauget
Eugene C. Cordero
The optimal ranking regime (ORR) method was used to identify intradecadal to multidecadal (IMD) time windows containing significant ranking sequences in U.S. climate division temperature data. The simplicity of the ORR procedure’s output—a time series’ most significant nonoverlapping periods of high or low rankings—makes it possible to graphically identify common temporal breakpoints and spatial patterns of IMD variability in the analyses of 102 climate division temperature series. This approach is also applied to annual Atlantic multidecadal oscillation (AMO) and Pacific decadal oscillation (PDO) climate indices, a Northern Hemisphere annual temperature (NHT) series, and divisional annual and seasonal temperature data during …
Optimal Ranking Regime Analysis Of Intra- To Multidecadal U.S. Climate Variability. Part Ii: Precipitation And Streamflow, Steven A. Mauget, Eugene C. Cordero
Optimal Ranking Regime Analysis Of Intra- To Multidecadal U.S. Climate Variability. Part Ii: Precipitation And Streamflow, Steven A. Mauget, Eugene C. Cordero
Eugene C. Cordero
In Part I of this paper, the optimal ranking regime (ORR) method was used to identify intradecadal to multidecadal (IMD) regimes in U.S. climate division temperature data during 1896–2012. Here, the method is used to test for annual and seasonal precipitation regimes during that same period. Water-year mean streamflow rankings at 125 U.S. Hydro-Climatic Data Network gauge stations are also evaluated during 1939–2011. The precipitation and streamflow regimes identified are compared with ORR-derived regimes in the Pacific decadal oscillation (PDO), the Atlantic multidecadal oscillation (AMO), and indices derived from gridded SST anomaly (SSTA) analysis data. Using a graphic display approach …
Linked-Cluster Expansion For The Green's Function Of The Infinite-U Hubbard Model, Ehsan Khatami, Edward Perepelitsky, Marcos Rigol, Sriram B. Shastry
Linked-Cluster Expansion For The Green's Function Of The Infinite-U Hubbard Model, Ehsan Khatami, Edward Perepelitsky, Marcos Rigol, Sriram B. Shastry
Ehsan Khatami
We implement a highly efficient strong-coupling expansion for the Green's function of the Hubbard model. In the limit of extreme correlations, where the onsite interaction is infinite, the evaluation of diagrams simplifies dramatically enabling us to carry out the expansion to the eighth order in powers of the hopping amplitude. We compute the finite-temperature Green's function analytically in the momentum and Matsubara frequency space as a function of the electron density. Employing Padé approximations, we study the equation of state, Kelvin thermopower, momentum distribution function, quasiparticle fraction, and quasiparticle lifetime of the system at temperatures lower than, or of the …
Magnetic Correlations And Pairing In The 1/5-Depleted Square Lattice Hubbard Model, Ehsan Khatami, Rajiv R.P. Singh, Warren E. Pickett, Richard T. Scalettar
Magnetic Correlations And Pairing In The 1/5-Depleted Square Lattice Hubbard Model, Ehsan Khatami, Rajiv R.P. Singh, Warren E. Pickett, Richard T. Scalettar
Ehsan Khatami
We study the single-orbital Hubbard model on the 1/5-depleted square-lattice geometry, which arises in such diverse systems as the spin-gap magnetic insulator CaV4O9 and ordered-vacancy iron selenides, presenting new issues regarding the origin of both magnetic ordering and superconductivity in these materials. We find a rich phase diagram that includes a plaquette singlet phase, a dimer singlet phase, a Néel and a block-spin antiferromagnetic phase, and stripe phases. Quantum Monte Carlo simulations show that the dominant pairing correlations at half filling change character from d wave in the plaquette phase to extended s wave upon transition to the Néel phase. …