Revealing microscopic origins of shape coexistence in the Ni isotopic chain

In a two–neutron transfer experiment, performed in Bucharest in July 2016 at sub–Coulomb barrier energy,a photon decay hindered – solely – by a nuclear shape change was identified in the 66Ni nucleus. Such a rare process, at spin zero, was clearly observed before only in actinide nuclei in the 1970’s,where fission isomers were found. The experimental findings on 66Ni have been well reproduced by the Monte Carlo Shell Model Calculations of the Tokyo group, which predict a multifaceted scenario of coexistence of spherical, oblate and prolate shapes in neutron–rich Ni isotopes. The results on 66Ni encouraged a comprehensive gamma–spectroscopy investigation of neutron–rich Ni isotopes, in particular 62Ni and 64–Ni, at IFIN–HH (Bucharest), IPN Orsay and ILL (Grenoble), employing different reaction mechanisms to pin down the wave function composition of selected excited states. The aim is to shed light on the microscopic origin of deformation in neutron–rich Ni nuclei, possibly locating other examples of “shape–isomer–like” structures inthis region.

Download Full-text

Patterns of Locomotor Drive to Motoneurons and Last-Order Interneurons: Clues to the Structure of the CPG

Journal of Neurophysiology ◽

10.1152/jn.2001.86.1.447 ◽

2001 ◽

Vol 86 (1) ◽

pp. 447-462 ◽

Cited By ~ 105

Author(s):

R. E. Burke ◽

A. M. Degtyarenko ◽

E. S. Simon

Keyword(s):

Fictive Locomotion ◽

Cutaneous Reflex ◽

Reflex Pathways ◽

Locomotor Control ◽

Low Threshold ◽

Experimental Findings ◽

Differential Control ◽

Flexor Digitorum ◽

First Time ◽

Shed Light

We have examined the linkage between patterns of activity in several hindlimb motor pools and the modulation of oligosynaptic cutaneous reflex pathways during fictive locomotion in decerebrate unanesthetized cats to assess the notion that such linkages can shed light on the structure of the central pattern generator (CPG) for locomotion. We have concentrated attention on the cutaneous reflex pathways that project to the flexor digitorum longus (FDL) motor pool because of that muscle's unique variable behavior during normal and fictive locomotion in the cat. Differential locomotor control of last-order excitatory interneurons in pathways from low-threshold cutaneous afferents in the superficial peroneal and medial plantar afferents to FDL motoneurons is fully documented for the first time. The qualitative patterns of differential control are shown to remain the same whether the FDL muscle is active in early flexion, as usually found, or during the extension phase of fictive locomotion, which is less common during fictive stepping. The patterns of motor pool activity and of reflex pathway modulation indicate that the flexion phase of fictive locomotion has distinct early versus late components. Observations during “normal” and unusual patterns of fictive stepping suggest that some aspects of locomotor pattern formation can be separated from rhythm generation, implying that these two CPG functions may be embodied, at least in part, in distinct neural organizations. The results are discussed in relation to a provisional circuit diagram that could explain the experimental findings.

Download Full-text

Hydrodynamics of flagellated microswimmers near free-slip interfaces

Journal of Fluid Mechanics ◽

10.1017/jfm.2015.738 ◽

2016 ◽

Vol 789 ◽

pp. 514-533 ◽

Cited By ~ 27

Author(s):

D. Pimponi ◽

M. Chinappi ◽

P. Gualtieri ◽

C. M. Casciola

Keyword(s):

Numerical Solutions ◽

Stokes Equations ◽

Slip Surface ◽

Initial Conditions ◽

Aerobic Bacteria ◽

Slip Boundary ◽

Experimental Findings ◽

Micro Organisms ◽

Air Interfaces ◽

Shed Light

The hydrodynamics of a flagellated micro-organism is investigated when swimming close to a planar free-slip surface by means of numerical solutions of the Stokes equations obtained via a boundary element method. Depending on the initial conditions, the swimmer can either escape from the free-slip surface or collide with the boundary. Interestingly, the micro-organism does not exhibit a stable orbit. Independently of escape or attraction to the interface, close to a free-slip surface, the swimmer follows a counter-clockwise trajectory, in agreement with experimental findings (Di Leonardo et al., Phys. Rev. Lett., vol. 106 (3), 2011, 038101). The hydrodynamics is indeed modified by the free surface. In fact, when the same swimmer moves close to a no-slip wall, a set of initial conditions exists which result in stable orbits. Moreover, when moving close to a free-slip or a no-slip boundary, the swimmer assumes a different orientation with respect to its trajectory. Taken together, these results contribute to shed light on the hydrodynamical behaviour of micro-organisms close to liquid–air interfaces which are relevant for the formation of interfacial biofilms of aerobic bacteria.

Download Full-text

Monte Carlo shell model calculations for medium-mass nuclei

10.1063/1.59527 ◽

1999 ◽

Author(s):

Takaharu Otsuka ◽

Takahiro Mizusaki ◽

Yutaka Utsuno ◽

Michio Honma

Keyword(s):

Monte Carlo ◽

Shell Model ◽

Model Calculations ◽

Medium Mass ◽

Monte Carlo Shell Model

Download Full-text

Monte-Carlo Shell Model calculations of Xe and Ba isotopes

Journal of Physics Conference Series ◽

10.1088/1742-6596/49/1/042 ◽

2006 ◽

Vol 49 ◽

pp. 178-183 ◽

Cited By ~ 7

Author(s):

N Shimizu ◽

T Otsuka ◽

T Mizusaki ◽

M Honma

Keyword(s):

Monte Carlo ◽

Shell Model ◽

Model Calculations ◽

Monte Carlo Shell Model

Download Full-text

Some Theoretical Aspects of Carbon Incorporation into III-V“s

MRS Proceedings ◽

10.1557/proc-282-711 ◽

1992 ◽

Vol 282 ◽

Author(s):

Markus Weyers

Keyword(s):

Carbon Doping ◽

Complete Understanding ◽

Carbon Incorporation ◽

Group V ◽

Model Calculations ◽

Group Iii ◽

Carbon Doped ◽

Host Materials ◽

Experimental Findings ◽

Bulk Semiconductor

ABSTRACTCarbon as a constituent of some of the source molecules is always present in the metalorganic growth techniques and can potentially be incorporated into the grown layers. Unintentional carbon incorporation as well as intentional carbon doping of III-V compounds has been studied intensely, especially in the case of GaAs. However, a number of experimental findings still is not well understood. Besides the different electrical behavior of carbon in different host materials (acceptor in GaAs, donor in InAs) also the different probability of incorporation into, for example, GaAs compared to InAs is currently not well explained. Model calculations may provide useful hints to enhance the understanding of the experimentally observed trends. In this paper, two different approaches will be reviewed and their results will be discussed.The first approach is dealing with the expected incorporation site of carbon in III-V“s. The change in total energy associated with substitutional carbon incorporation onto group III or group V lattice sites has been calculated. From this change the conduction type of carbon doped arsenides and phosphides (except for InAs) can correctly be predicted. While this method is dealing with the bulk semiconductor, the second approach attempts to model the binding energy of methyl to atoms on the growing surface. By using appropriate molecules the methyl bond strength can be estimated. Both approaches together provide a basis for a more complete understanding of carbon incorporation behavior in III-V compounds.

Download Full-text

Centrality Dependences of Characteristics of Negative Pions in π− +12C Interactions at 40 GeV/c

Ukrainian Journal of Physics ◽

10.15407/ujpe64.2.93 ◽

2019 ◽

Vol 64 (2) ◽

pp. 93 ◽

Cited By ~ 1

Author(s):

Kh. K. Olimov ◽

K. Olimov ◽

Sh. D. Tojimamatov ◽

A. K. Olimov ◽

E. Kh. Bozorov ◽

...

Keyword(s):

Transverse Momentum ◽

Emission Angle ◽

Model Calculations ◽

Average Value ◽

Collision Centrality ◽

Binary Collisions ◽

Momentum Distributions ◽

The Mean ◽

Experimental Findings ◽

Fritiof Model

The collision centrality dependences of the mean multiplicities and kinematical characteristics of negative pions produced in п−+12C collisions at 40 GeV/с are investigated. It is obtained that the average values of the partial inelasticity coefficients of negative pions (without “leading” pions) do not depend on the п−+12C collision centrality. It is shown that the normalized transverse momentum distributions, as well as the average values of the transverse momentum of negative pions, do not depend within the uncertainties on the п−+12C collision centrality. The average value of the emission angle of the negative pions was found to increase with the п−+12C collision centrality. The comparison of the normalized emission angle distributions of the negative pions in the peripheral and central п−+12C collisions at 40 GeV/с supported the assumption that such an increase in the average emission angle is likely due to an increase in the number of binary collisions and multiple rescatterings with the п−+12C collision centrality. The obtained experimental findings are reproduced qualitatively well by the Modified FRITIOF model calculations.

Download Full-text

Measurement of the Time-like Pion Transition Form Factor at BESIII

EPJ Web of Conferences ◽

10.1051/epjconf/201921204013 ◽

2019 ◽

Vol 212 ◽

pp. 04013

Author(s):

Thomas Lenz ◽

Achim Denig ◽

Christoph Florian Redmer

Keyword(s):

Form Factor ◽

Magnetic Moment ◽

Anomalous Magnetic Moment ◽

Transition Form Factor ◽

High Momentum ◽

Transition Form ◽

Model Calculations ◽

The Standard Model ◽

Important Input ◽

Shed Light

The pion transition form factor is an important input to the dispersive approaches of the Standard Model calculations for the anomalous magnetic moment of the muon. We report the prospects of a first measurement at high momentum transfer in the time-like region performed at BESIII. The aim is to improve the uncertainty of the hadronic light-by-light calculations and to shed light on the BaBar-Belle puzzle in the space-like region.

Download Full-text