Sexual behavior: social and ecological influences in the anabantoid fish, Trichogaster trichopterus

The influence of behavioral and environmental variables on the initiation of spawning in Trichogaster trichopterus was investigated. The behavioral responses of isolated males and females to conspecific visual and chemical stimuli were also examined. Fish in divided aquaria were administered visual cues of a conspecific through a glass partition, chemical cues by an exchange of water between the two chambers, or both visual and chemical cues. Males and females differed in their response to stimuli from the opposite sex. In addition, responses differed with the sex of the stimulus fish. Chemical cues elicited nest building in males but not females. In the spawning experiments, when one member of a pair of fish was exchanged daily, the male spawned the first day without a nest. The female spawned only after several days. Two manipulations shortened spawning latency: Introducing a new male daily and isolating the female for 3 days in the spawning aquarium prior to union with a male. Spawning was delayed, or did not occur, when the female was exchanged each day during the mating period or when a second, smaller female was kept in the spawning aquarium for 3 days prior to introduction of a male. These results suggest that the induction of spawning readiness in females is more susceptible to social and environmental variables than it is in males.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22386/1/0000835.pd

Effects of electroconvulsive shock and puromycin on operant responding in goldfish

Goldfish were conditioned to strike an operandum for food reward on a variable interval schedule. Well-established patterns of operant responding were disrupted for up to several days when the fish were convulsed by a 1 sec transcranial shock immediately following a regular daily session. No lasting interference was seen when fish were shocked 19.5 hr postsession. The results suggest that the convulsive shock has aversive consequences which can be conditioned to stimuli associated with the training environment in a single presentation. Intracranial administration of 170 [mu]g of puromycin immediately following a session did not disrupt responding.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34129/1/0000413.pd

Nuclear spins, magnetic moments and quadrupole moments of Cu isotopes from N = 28 to N = 46: probes for core polarization effects

Measurements of the ground-state nuclear spins, magnetic and quadrupole moments of the copper isotopes from 61Cu up to 75Cu are reported. The experiments were performed at the ISOLDE facility, using the technique of collinear laser spectroscopy. The trend in the magnetic moments between the N=28 and N=50 shell closures is reasonably reproduced by large-scale shell-model calculations starting from a 56Ni core. The quadrupole moments reveal a strong polarization of the underlying Ni core when the neutron shell is opened, which is however strongly reduced at N=40 due to the parity change between the $pf$ and $g$ orbits. No enhanced core polarization is seen beyond N=40. Deviations between measured and calculated moments are attributed to the softness of the 56Ni core and weakening of the Z=28 and N=28 shell gaps.Comment: 13 pagers, 19 figures, accepted by Physical Review

Halos and related structures

The halo structure originated in nuclear physics but is now encountered more widely. It appears in loosely bound, clustered systems where the spatial extension of the system is significantly larger than that of the binding potentials. A review is given on our current understanding of these structures, with an emphasis on how the structures evolve as more cluster components are added, and on the experimental situation concerning halo states in light nuclei.Comment: 27 pages, 3 figures, Contribution to Nobel Symposium 152 "Physics With Radioactive Beams

The Lived Experience of Paradox:How Individuals Navigate Tensions during the Pandemic Crisis

This is a dialogue and part of an article series involving many authors. </p

Precision Measurement of the First Ionization Potential of Nobelium

One of the most important atomic properties governing an element’s chemical behavior is the energy required to remove its least-bound electron, referred to as the first ionization potential. For the heaviest elements, this fundamental quantity is strongly influenced by relativistic effects which lead to unique chemical properties. Laser spectroscopy on an atom-at-a-time scale was developed and applied to probe the optical spectrum of neutral nobelium near the ionization threshold. The first ionization potential of nobelium is determined here with a very high precision from the convergence of measured Rydberg series to be 6.626   21 ± 0.000   05     eV . This work provides a stringent benchmark for state-of-the-art many-body atomic modeling that considers relativistic and quantum electrodynamic effects and paves the way for high-precision measurements of atomic properties of elements only available from heavy-ion accelerator facilities

Linear viscoelasticity - bone volume fraction relationships of bovine trabecular bone

Trabecular bone has been previously recognized as time-dependent (viscoelastic) material, but the relationships of its viscoelastic behaviour with bone volume fraction (BV/TV) have not been investigated so far. Therefore, the aim of the present study was to quantify the time-dependent viscoelastic behaviour of trabecular bone and relate it to BV/TV. Uniaxial compressive creep experiments were performed on cylindrical bovine trabecular bone samples ([Formula: see text] ) at loads corresponding to physiological strain level of 2000 [Formula: see text] . We assumed that the bone behaves in a linear viscoelastic manner at this low strain level and the corresponding linear viscoelastic parameters were estimated by fitting a generalized Kelvin–Voigt rheological model to the experimental creep strain response. Strong and significant power law relationships ([Formula: see text] ) were found between time-dependent creep compliance function and BV/TV of the bone. These BV/TV-based material properties can be used in finite element models involving trabecular bone to predict time-dependent response. For users’ convenience, the creep compliance functions were also converted to relaxation functions by using numerical interconversion methods and similar power law relationships were reported between time-dependent relaxation modulus function and BV/TV