532 research outputs found
Renormalization of the one-loop theory of fluctuations in polymer blends and diblock copolymer melts
Attempts to use coarse-grained molecular theories to calculate corrections to
the random-phase approximation (RPA) for correlations in polymer mixtures have
been plagued by an unwanted sensitivity to the value of an arbitrary cutoff
length, {\it i.e.}, by an ultraviolet (UV) divergence. We analyze the UV
divergence of the inverse structure factor predicted by a
`one-loop' approximation similar to that used in several previous studies. We
consider both miscible homopolymer blends and disordered diblock copolymer
melts. We show, in both cases, that all UV divergent contributions can be
absorbed into a renormalization of the values of the phenomenological
parameters of a generalized self-consistent field theory (SCFT). This
observation allows the construction of a UV convergent theory of corrections to
SCFT phenomenology. The UV-divergent one-loop contribution to are
shown to be the sum of: (i) a -independent contribution that arises from a
renormalization of the effective parameter, (ii) a -dependent
contribution that arises from a renormalization of monomer statistical segment
lengths, (iii) a contribution proportional to that arises from a
square-gradient contribution to the one-loop fluctuation free energy, and (iv)
a -dependent contribution that is inversely proportional to the degree of
polymerization, which arises from local perturbations in fluid structure near
chain ends and near junctions between blocks in block copolymers.Comment: 35 pages, 2 figure
First observation of 55,56Zn
In an experiment at the SISSI/LISE3 facility of GANIL, the most proton-rich
zinc isotopes 55,56Zn have been observed for the first time. The experiment was
performed using a high-intensity 58Ni beam at 74.5 MeV/nucleon impinging on a
nickel target. The identification of 55,56Zn opens the way to 54Zn, a good
candidate for two-proton radioactivity according to theoretical predictions.Comment: 2 pages, 1 figure, accepted for publication in Eur. Phys. J.
Decay of proton-rich nuclei between 39Ti and 49Ni
Decay studies of very neutron-deficient nuclei ranging from 39Ti to 49Ni have
been performed during a projectile fragmentation experiment at the GANIL/LISE3
separator. For all nuclei studied in this work, 39,40Ti, 42,43Cr, 46Mn,
45,46,47Fe and 49Ni, half-lives and decay spectra have been measured. In a few
cases, gamma coincidence measurements helped to successfully identify the
initial and final states of transitions. In these cases, partial decay scheme
are proposed. For the most exotic isotopes, 39Ti, 42Cr, 45Fe and 49Ni, which
are candidates for two-proton radioactivity from the ground state, no clear
evidence of this process is seen in our spectra and we conclude rather on a
delayed particle decay.Comment: 12 pages, 15 figures, submitted for publication in Eur. Phys. J.
How magic is the magic 68Ni nucleus?
We calculate the B(E2) strength in 68Ni and other nickel isotopes using
several theoretical approaches. We find that in 68Ni the gamma transition to
the first 2+ state exhausts only a fraction of the total B(E2) strength, which
is mainly collected in excited states around 5 MeV. This effect is sensitive to
the energy splitting between the fp shell and the g_{9/2}orbital. We argue that
the small experimental B(E2) value is not strong evidence for the double-magic
character of 68Ni.Comment: 4 pages, 4 figure
Analysis of DRD2 Gene Polymorphism in the Context of Personality Traits in a Group of Athletes
The presented study showed the relationship between dopamine receptor gene polymorphism and personality traits in athletes training in martial arts. Behavioral modulation resulting from a balance of the neurotransmitters dopamine and norepinephrine to inactivation of the dorsolateral prefrontal cortex and dysregulation of various pathways involved in attention and impulse control processes; Methods: The study was conducted among martial arts athletes. The study group included 258 volunteers and 284 controls. The genetic test was performed using the real-time PCR method; psychological tests were performed using standardized TCI questionnaires. All analyses were performed using STATISTICA 13. Results: Interaction between martial arts and DRD2 rs1799732 (manual) G/-(VIC/FAM)-ins/del and RD- Harm avoidance and Reward Dependence scale were demonstrated. In athletes, a lower Reward Dependence scale score was associated with the DRD2 rs1799732 (manual)-/-polymorphism compared to the control group. Conclusions: It seems justified to study not only genetic aspects related to brain transmission dopamine in martial arts athletes. In the studied athletes, the features related to reward addiction and harm avoidance are particularly important in connection with the dopaminergic reward system in the brai
Orbital dependent nucleonic pairing in the lightest known isotopes of tin
By studying the 109Xe-->105Te-->101Sn superallowed alpha-decay chain, we
observe low-lying states in 101Sn, the one-neutron system outside doubly magic
100Sn. We find that the spins of the ground state (J = 7=2) and first excited
state (J = 5=2) in 101Sn are reversed with respect to the traditional level
ordering postulated for 103Sn and the heavier tin isotopes. Through simple
arguments and state-of-the-art shell model calculations we explain this
unexpected switch in terms of a transition from the single-particle regime to
the collective mode in which orbital-dependent pairing correlations, dominate.Comment: 5 pages 3 figure
On the discovery of doubly-magic Ni
The paper reports on the first observation of doubly-magic Nickel-48 in an
experimental at the SISSI/LISE3 facility of GANIL. Four Nickel-48 isotopes were
identified. In addition, roughly 100 Nickel-49, 50 Iron-45, and 290 Chromium-42
isotopes were observed. This opens the possibility to search for two-proton
emission from these nuclei.Comment: 4 pages, 3 figures, accepted for publication in Phys. Rev. Let
Beta decay of 71,73Co; probing single particle states approaching doubly magic 78Ni
Low-energy excited states in 71,73Ni populated via the {\beta} decay of
71,73Co were investigated in an experiment performed at the National
Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU).
Detailed analysis led to the construction of level schemes of 71,73Ni, which
are interpreted using systematics and analyzed using shell model calculations.
The 5/2- states attributed to the the f5/2 orbital and positive parity 5/2+ and
7/2+ states from the g9/2 orbital have been identified in both 71,73Ni. In 71Ni
the location of a 1/2- {\beta}-decaying isomer is proposed and limits are
suggested as to the location of the isomer in 73Ni. The location of positive
parity cluster states are also identified in 71,73Ni. Beta-delayed neutron
branching ratios obtained from this data are given for both 71,73Co.Comment: Accepted for publication in PR
- …