270 research outputs found
Deformation of hypernuclei studied with antisymmetirzed molecular dynamics
An extended version of the antisymmetrized molecular dynamics to study
structure of - shell hypernuclei is developed. By using an effective
interaction, we investigate energy curves of Be,
C and Ne as function of nuclear quadrupole
deformation. Change of nuclear deformation caused by particle is
discussed. It is found that the in p-wave enhances nuclear
deformation, while that in s-wave reduces it. This effect is most prominent in
C. The possibility of the parity inversion in Ne
is also examined
Modification of triaxial deformation and change of spectrum in $^{25}_{\ \Lambda}\Lambda$ hyperon
The positive-parity states of Mg with a hyperon
in orbit were studied with the antisymmetrized molecular dynamics for
hypernuclei. We discuss two bands of Mg corresponding to the
and bands of Mg. It is found that the energy of the
band is shifted up by about 200 keV compared to
Mg. This is because the hyperon in orbit reduces the
quadrupole deformation of the band, while it
does not change the deformation of the band
significantly.Comment: 19 pages, 3 figure
Examining a Habitat-Weather Threshold for Northern Bobwhite Populations in the Southwestern United States
In semiarid portions of the northern bobwhite (Colinus virginianus; hereafter, bobwhite) geographic distribution, weather is a strong driver of interannual abundance. However, the strength of this relationship may depend on habitat amount. Given this habitat–weather dependence, there is likely to be a threshold value for habitat that determines how strongly a bobwhite population responds to weather. Our objective was to evaluate the relationship between habitat amount and the relative influence of weather on bobwhite abundance in Texas and Oklahoma, USA and determine a potential land-cover threshold value. We collected bobwhite abundance and land-cover data from the Breeding Bird Survey and National Land Cover Database, respectively, for 2 time periods which corresponded to historical lows (2012–2013) and highs (2015–2016) of bobwhite abundance within this region. We reclassified land cover into grassland, shrubland, pastureland, cropland, forest, and urban cover, and combined grassland and shrubland categories to represent bobwhite habitat. We used weighted linear regression to model the difference between mean bobwhite abundance between each time period as a function of habitat amount, hypothesizing a positive, linear relationship given the theorized greater influence of weather on populations within higher habitat amounts. To evaluate a potential habitat threshold, we modeled mean bobwhite abundance, for each time period, and all individual land-cover variables using a generalized additive model with a negative binomial distribution. We detected a positive, linear relationship between habitat amount and the difference between high and low bobwhite populations (r2 = 0.30), per our hypothesis. Models of land-cover variables differed between low- and high-abundance time periods. The time period of lower abundance (2012–2013) model included all land-cover variables except cropland and showed significant positive, linear relationships with grass and hay cover, and negative, linear relationships with forest and urban cover. Shrubland cover was the only nonlinear term, increasing to approximately 50–60% cover, then decreasing sharply with increasing cover. Deviance explained for this model was 41.2%. For the period of high abundance (2015–2016) the model explained approximately 25% of the deviance and was reduced to only negative, linear relationships with forest and urban cover. Our results provide some evidence toward the habitat–weather threshold hypothesis. Additionally, while no land-cover values showed a threshold-like relationship with bobwhite abundance, we did document differences in variable selection for each time period. Stressors on bobwhite habitat seem to have a more dramatic impact on bobwhite populations than available habitat, especially in periods of higher abundance, whereas periods of lower abundance also included habitat variables
Effect of Donepezil on Group II mGlu Receptor Agonist- or Antagonist-Induced Amnesia on Passive Avoidance in Mice
We examined the effect of the acetylcholinesterase
(ACHE) inhibitor, donepezil
hydrocloride (DONP), on group II metabotropic
glutamate (mGlu) receptor agonist- or
antagonist-induced amnesia in the step-through
passive avoidance task in male mice. DCG-IV, a
group II mGlu receptor agonist, at dose of 50
ng and LY341495, a group II mGlu receptor
antagonist, at dose of 300 ng, significantly
attenuated the latency on the step-through task.
The subcutaneous injection of DONP at dose of
1 mg/kg 1 hour before passive avoidance
performance ameliorated the amnesia induced
by DCG-IV and LY341495, whereas donepezil
alone did not affect task latency. The results
suggest that activation of group II mGlu
receptors and disinhibition of the cAMP/PKA
signaling pathway (caused by group II mGlu
receptor antagonist) have a negative action on
step-through passive avoidance memory
performance, and that group II mGlu receptors
and ACh interact to modulate learning and
memory function
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