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Journal Articles

A Numerical study of turbulence statistics and the structure of a spatially-developing boundary layer over a realistic urban geometry

Inagaki, Atsushi*; Kanda, Manabu*; Ahmad, N. H.*; Yagi, Ayako*; Onodera, Naoyuki; Aoki, Takayuki*

Boundary-Layer Meteorology, 164(2), p.161 - 181, 2017/08

 Times Cited Count:30 Percentile:75.23(Meteorology & Atmospheric Sciences)

The applicability of outer-layer scaling is examined by numerical simulation of a developing neutral boundary layer over a realistic building geometry of Tokyo. Large-eddy simulations are carried out over a large computational domain 19.2 km $$times$$ 4.8 km $$times$$1 km, with a fine grid spacing (2 m) using the lattice-Boltzmann method with massively parallel graphics processing units. Results from simulations show that outer-layer features are maintained for turbulence statistics in the upper part of the boundary layer, as well as the width of predominant streaky structures throughout the entire boundary layer. This is caused by the existence of very large streaky structures extending throughout the entire boundary layer, which follow outer-layer scaling with a self-preserving development. We assume the top-down mechanism in the physical interpretation of results.

Journal Articles

Population and decay of a $$K^{pi}$$ = 8$$^{-}$$ two-quasineutron isomer in $$^{244}$$Pu

Hota, S.*; Tandel, S.*; Chowdhury, P.*; Ahmad, I.*; Carpenter, M. P.*; Chiara, C. J.*; Greene, J. P.*; Hoffman, C. R.*; Jackson, E. G.*; Janssens, R. V. F.*; et al.

Physical Review C, 94(2), p.021303_1 - 021303_5, 2016/08

 Times Cited Count:6 Percentile:44.49(Physics, Nuclear)

The decay of a $$K^{pi}$$ = 8$$^{-}$$ isomer in $$^{244}$$Pu and the collective band structure populating the isomer are studied using deep inelastic excitations with $$^{47}$$Ti and $$^{208}$$Pb beams, respectively. Precise measurements of $$M1/E2$$ branching ratios in the band confirm a clean 9/2$$^-$$[734]$$_{nu}$$$$otimes$$7/2$$^+$$[624]$$_{nu}$$ for the isomer, validating the systematics of K$$^{pi}$$ = 8$$^{-}$$ two-quasineutron isomers observed in even-$$Z$$, $$N$$ = 150 isotones. These isomers around the deformed shell gap at $$N$$ = 152 provide critical benchmarks for theoretical predictions of single-particle energies in this gateway region to superheavy nuclei.

Journal Articles

Search for a 2-quasiparticle high-$$K$$ isomer in $$^{256}$$Rf

Robinson, A. P.*; Khoo, T. L.*; Seweryniak, D.*; Ahmad, I.*; Asai, Masato; Back, B. B.*; Carpenter, M. P.*; Chowdhury, P.*; Davids, C. N.*; Greene, J.*; et al.

Physical Review C, 83(6), p.064311_1 - 064311_7, 2011/06

 Times Cited Count:32 Percentile:84.86(Physics, Nuclear)

We have identified an isomer with a half-life of 17 $$mu$$s in $$^{256}$$Rf through a calorimetric conversion electron measurement tagged with implanted $$^{256}$$Rf nuclei using the fragment mass analyzer at Argonne National Laboratory. The low population yield for this isomer suggests that this isomer should not be a 2-quasiparticle high-$$K$$ isomer which is typically observed in the N = 152 isotones, but should be a 4-quasiparticle one. Possible reasons of the non-observation of a 2-quasiparticle isomer are this isomer decays by fission with a half-life similar to that of the ground state of $$^{256}$$Rf. Another possibility, that there is no 2-quasiparticle isomer at all, would imply an abrupt termination of axially symmetric deformed shape at Z=104.

Journal Articles

Bridging the nuclear structure gap between stable and super heavy nuclei

Seweryniak, D.*; Khoo, T. L.*; Ahmad, I.*; Kondev, F. G.*; Robinson, A.*; Tandel, S. K.*; Asai, Masato; Back, B. B.*; Carpenter, M. P.*; Chowdhury, P.*; et al.

Nuclear Physics A, 834(1-4), p.357c - 361c, 2010/03

 Times Cited Count:7 Percentile:47.82(Physics, Nuclear)

Experimental data on single-particle energies in nuclei around Z=100 and N=152 play an important role to test validity of theoretical predictions for shell structure of superheavy nuclei. We found high-K two-quasiparticle isomers in $$^{252}$$No and $$^{254}$$No, and evaluated energies of proton single-particle orbitals around Z=100. We also found a new high-K three quasiparticle isomer in $$^{257}$$Rf. Energies of neutron single-particle orbitals were also evaluated from experimental data of the $$alpha$$ decay of $$^{257}$$Rf. Comparisons between the present experimental data and various theoretical calculations for the proton single-particle orbitals indicate that the calculation by using the Woods-Saxon potential gives the best agreement with the data.

Journal Articles

Spectroscopy of $$^{257}$$Rf

Qian, J.*; Heinz, A.*; Khoo, T. L.*; Janssens, R. V. F.*; Peterson, D.*; Seweryniak, D.*; Ahmad, I.*; Asai, Masato; Back, B. B.*; Carpenter, M. P.*; et al.

Physical Review C, 79(6), p.064319_1 - 064319_13, 2009/06

 Times Cited Count:31 Percentile:83.95(Physics, Nuclear)

$$alpha$$-, $$gamma$$-, and conversion electron spectroscopy experiments for $$^{257}$$Rf have been performed using Fragment Mass Analyzer at Argonne National Laboratory. A new isomer with a half-life of 160 $$mu$$s has been discovered in $$^{257}$$Rf, and it is interpreted as a three-quasiparticle high-$$K$$ isomer. Neutron configurations of one-quasiparticle states in $$^{253}$$No, the $$alpha$$-decay daughter of $$^{257}$$Rf, have been assigned on the basis of $$alpha$$-decay hindrance factors. Excitation energies of the 1/2$$^{+}$$[620] states in $$N$$=151 isotones indicate that the deformed shell gap at $$N$$=152 increases with the atomic number.

Journal Articles

$$K^{pi}=8^{-}$$ isomers and $$K^{pi}=2^{-}$$ octupole vibrations in $$N=150$$ shell-stabilized isotones

Robinson, A. P.*; Khoo, T. L.*; Ahmad, I.*; Tandel, S. K.*; Kondev, F. G.*; Nakatsukasa, Takashi*; Seweryniak, D.*; Asai, Masato; Back, B. B.*; Carpenter, M. P.*; et al.

Physical Review C, 78(3), p.034308_1 - 034308_6, 2008/09

 Times Cited Count:49 Percentile:90.87(Physics, Nuclear)

Isomers have been identified in $$^{246}$$Cm and $$^{252}$$No with quantum number $$K^{pi}=8^{-}$$, which decay through $$K^{pi}=2^{-}$$ rotational bands built on octupole vibrational states. For $$N=150$$ isotones with atomic number $$Z=94$$$$sim$$102, the $$K^{pi}=8^{-}$$ and 2$$^{-}$$ states have remarkably stable energies, indicating neutron excitations. An exception is a singular minimum in the 2$$^{-}$$ energy at $$^{246}$$Cm, due to the additional role of proton configurations.

Journal Articles

Structure-based calculation of direct and indirect readout energies and specificities for protein-DNA recognition

Ahmad, S.*; Kono, Hidetoshi; Ara$'u$zo-Bravo, M. J.*; Sarai, Akinori*

Nucleic Acids Research, 34(Suppl.2), p.W124 - W127, 2006/07

 Times Cited Count:31 Percentile:49.98(Biochemistry & Molecular Biology)

no abstracts in English

Journal Articles

Sequence-dependent conformational energy of DNA derived from molecular dynamics simulations; Toward understanding the indirect readout mechanism in protein-DNA recognition

Ara$'u$zo-Bravo, M. J.*; Fujii, Satoshi*; Kono, Hidetoshi; Ahmad, S.*; Sarai, Akinori*

Journal of the American Chemical Society, 127(46), p.16074 - 16089, 2005/11

 Times Cited Count:46 Percentile:73.02(Chemistry, Multidisciplinary)

no abstracts in English

Oral presentation

Balance of direct readout and indirect readout contributions to protein-DNA recognition

Kono, Hidetoshi; Kumar, S.*; Ahmad, S.*; Ara$'u$zo-Bravo, M. J.*; Fujii, Satoshi*; Go, Nobuhiro; Sarai, Akinori*

no journal, , 

no abstracts in English

Oral presentation

Prediction of transcription factors and their targets; Application to yeast genome

Sarai, Akinori*; Ueno, Takuya*; Ngahu, A.*; Ahmad, S.*; Kono, Hidetoshi

no journal, , 

no abstracts in English

Oral presentation

Detection of DNA polymorphisms induced by ion beam irradiation on three orchid species

Affrida, A. H.*; Ahmad, Z.*; Idris, N. A.*; Mohd Randzan, N.*; Idris, N.*; Basiran, M. N.*; Tanaka, Atsushi; Shikazono, Naoya; Ono, Yutaka; Hase, Yoshihiro

no journal, , 

Mutation induction by ion beam provides an alternative for improvement of orchids. The protocorm-like bodies (PLBs) of three orchid species; ${it Dendrobium crumenatum}$, ${it Dendrobium mirbellianum}$ and ${it Oncidium lanceanum}$ were irradiated with $$^{12}$$C$$^{5+}$$ ions, accelerated by AVF Cyclotron at Japanese Atomic Energy Agency (JAEA), Japan, at various doses ranging from 0 to 12.0 Gray (Gy). Since no morphological change was detected, Amplified Fragment Length Polymorphism (AFLP) technique was used to analyse the irradiated orchids. This PCR based DNA fingerprinting technique involves digestion of DNA with restriction enzymes, ligation of adapter and selective amplification using primer with one (pre-amplification) and three (selective amplification) arbitrary nucleotides. The fingerprinting of the control and mutant lines were compared in order to detect their genetic difference. Polymorphic fragments ranging from 250 to 1200 bp length were detected.

Oral presentation

Predictions of DNA-binding proteins and transcription factor targets in the yeast genome

Ngahu, A.*; Ueno, Takuya*; Ahmad, S.*; Kono, Hidetoshi; Sarai, Akinori*

no journal, , 

no abstracts in English

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