Unstable Pair Research Articles

Note on the evolution of the interface of an unstable granular solid-liquid pair

Note on the evolution of the interface of an unstable granular solid-liquid pair

Superconducting instability in the large-U limit of the two-dimensional Hubbard model

We have investigated numerically the pairing instabilities of Gutzwiller wavefunctions. These are equivalent to a certain form of the resonant valence bond wavefunction. The case considered is a nearly half-filled two dimensional band with interactions given by a Hubbard model with large on-site Coulomb interactions. We find that the paramagnetic normal state is unstable tod-wave pairing but stable againsts-wave pairing. The antiferromagnetic state is marginally stable against both types of pairing. These results can be explained as an interference effect resulting in enhanced antiferromagnetic spin correlation in the paired state.

Manifestations of social stress in grouped Japanese quail

1. 1. Physiological manifestations of social stress in stable and unstable (resident and visitor) pairs of adult male Japanese quail ( Coturnix coturnix japonica) were compared after 7, 14, 21 and 28 days of regrouping. 2. 2. Unstable pairs had reduced body and relative testes (mg/100 g) weights. 3. 3. Plasma cholesterol was increased significantly in unstable pairs, and adrenal cholesterol was reduced significantly by daily regrouping of unstable pairs. 4. 4. Twelve consecutive days of ACTH treatment (2, 4 or 8 IU/100 gbody wt given intramuscularly) to birds in stable pairs induced a decrease in body and relative testes weights. The results were similar to those found in birds subjected to daily regrouping.

Agonistic behavior and neurochemistry in grouped Japanese quail

1. 1. Aggressive behavior and whole brain neurochemistry were measured in stable and unstable pairs of male Coturnix coturnix japonica. 2. 2. Aggressive pecking peaked on day 5 of the daily regrouping regime and returned to a basal level on day 14. 3. 3. Aggressive behavior was associated with increased brain norepinephrine (NE), dopamine (DA), and acetylcholinesterase (AChE) in unstable pairs. 4. 4. Habituation (12–15 days) and DA response to daily regrouping and inanition were inversely related in unstable and stable pairs respectively. 5. 5. Normal whole brain NE increases were attenuated in unstable pairs.

Relationships of criminality and psychopathy with eight other apparent behavioral manifestations of sub-optimal arousal

The application of arousal theory to the study of criminality and psychopathy leads one to hypothesize that any behavior reflecting sub-optimal arousal should be more common among criminals and psychopaths than among their counterparts. In the present literature review, consistent support was found for this hypothesis by indicating the existence of substantial associations between criminality/psychopathy and the following eight behavior patterns: (1) resistance to punishment, (2) poor academic performance,or performance below intellectual potential, (3) impulsiveness, or minimal persistence at task assigned and coordinated by others, (4) childhood hyperactivity, (5) risk taking and sensation seeking, (6) recreation drug use, (7) preference for active social interactions, and (8) preference for broad-ranging sexual experiences and unstable pair bonding tendencies. Also consistent with arousal theory were numerous studies indicating that these eight behavior patterns were intercorrelated with one another. The conclusion suggested by this review was that criminality and psychopathy exists as part of a multi-variable cluster of behavior patterns which is a manifestation of sub-optimal arousal.

Disassociation of cadmium-vacancy complexes within the displacement spike.

Cadmium-vacancy complexes are formed in Al single crystals after implantation of Cd ions at 293 K. Postirradiation of these implants with ${\mathrm{H}}^{+}$ and ${\mathrm{Kr}}^{+}$ ions even at 5 K leads to an increase of the substitutional component (${f}_{s}$) of Cd in Al. The increase of ${f}_{s}$ is attributed to disassociation of neighboring Cd-vacancy pairs and serves as a quantitative measure for unstable pair recombination in the relaxation phase of the collision cascade. Our data support the results of molecular-dynamics calculations.

Spatial and temporal patterns in high-power ferromagnetic resonance.

Previous work on bifurcations and chaos in ferromagnetic resonance has singled out only the most unstable pair of spin waves for consideration, even though in general an entire manifold of spin wave is elegible for instability. This serious defect is removed here, and, as the result, we are able to calculate analytically the frequency of the limit cycle and its accompanying distinctive spatial correlation patterns.

The Coexistence of Unstable, Metastable, and Separated Frenkel Pair Defects in Solids. I. Basic Characteristics

AbstractThe existence of unstable, metastable, and separated states of Frenkel pair defects as well as their coexistence in solids are theoretically studied. Existence region, lifetime, and equilibrium concentration of defects in these states are determined and a phase diagram of defect states for KBr is also drawn. The unstability (spontaneous annihilation) zone radius of charged and neutral pair defects are estimated. It is shown that this zone radius is very large for charged (particularly, for multiple charged) pair defects, while for neutral pairs it is about the interatomic distance. Unstable pair lifetime is estimated as ≈ 10−12 s, while metastable pair life strongly depends on crystal temperature and decreases rapidly with rising temperature. The results obtained are in good agreement with available experimental data.

Energetics of mice in stable and unstable social conditions: Evidence of an air-borne factor affecting metabolism

The metabolic rates of laboratory mice were compared in three conditions: isolated mice, mice paired together over six days (stable groups), and mice paired with strange partners daily (unstable groups). Stable pairs had 15% lower metabolic rates than either isolated or unstable pairs. In other experiments when two mice were placed in separate metabolic chambers and connected together via an air flow, the metabolic rate of the recipient in the series was 35% lower than the donor. The data suggest that a ‘factor’ produced by the donor mouse was passed via the air supply into the recipient's chamber.

Unstable electron pairing and the energy loan model of enzyme catalysis

A theory of enzyme catalysis is described which utilizes a thermodynamically consistent construction of a free energy diagram with different pathways for complex formation and decomposition. The switch to the decomposition pathway occurs when downward uncertainty and thermal fluctuations make possible a short-lived potential energy dominance in which parallel spin electrons are paired and thus free to drop below the energy floor normally maintained by the Pauli exclusion principle. Such pairing is possible if van der Waal's and other weak interactions holding the complex together impose confinement constraints on parallel spin electrons, thereby both increasing uncertainty fluctuations in their kinetic energy and weakly favoring a phase correlation in their motion (which can be interpreted in terms of an exchange of virtual particles). The paired configuration is highly unstable and thus energy released by pair falling is either immediately recaptured to re-establish a normal orbital structure or, if the pair persists long enough to produce a nuclear motion, recaptured at the end of this motion. In the latter case the release of energy can be thought of as an energy loan which finances the switch to the lower activation energy pathway without compromising an energy-balanced regeneration of the enzyme. The advantage is that the complex (because of its instability) has a real free energy which is lower than the free energy which would be assigned to it on the basis of its equilibrium concentration. This increases the specificity and speed of complex formation without decreasing the speed of decomposition. The theory predicts that the magnetic moment which marks the pair should accompany the nuclear (e.g. allosteric) motion and that the pair formation stage of the enzymatic process should have an anomalous temperature dependence. Variations of the model may be constructed to deal with a number of processes involving macromolecular motions, including sequential processes in catalysis, allosteric control, persistent molecular motions, self-assembly, energy transfer, channeled transport, and protection against inhibitors.

Electron pairing as a source of cyclic instabilities in enzyme catalysis

Enzymatic reactions can be interpreted in terms of a thermodynamically consistent potential surface with different pathways for complex formation and decomposition. The construction suggests that unstable pairing of parallel spin electrons provides the basis for pathway switching.

AR associated with ANR-sequence and shape

For a given ANR-sequence ( X,A ) associated with a par ( X,A) of compacta, a pair ( N( X ), N( A )) of compact AR's containing ( X,A) as an unstable pair is constructed. The weak proper homotopy type of the pair ( N( X )-', N( A )- A) determines the shape of ( X,A) in the sense of Mardešić and Segal. Several applications of this result are given. A cohomological version of the Whitehead theorem in shape theory is proved.

Polarized Raman study of lattice modes and the 10°C phase transition of β-lithium ammonium sulphate

The Raman spectra of an oriented single crystal of β-LiNH 4SO 4 show that the first order phase transition involves a doubling of the primitive unit cell and is characterized by an unstable pair of degenerate phonons at the Brillouin zone boundary. This pair of phonons couples with the A 2 species strain component in the free energy expansion to give a term typical of improper ferroelastics.

CYTOTAXONOMIC STUDIES ON THE GENUS BOONACRIS: I. The "eastern" taxa and a comparison with the related genera Dendrotettix and Appalachia (Orthoptera: Catantopidae: Podismini)

Thirteen populations of four distinct taxa in the wingless grasshopper genus Boonacris with an eastern distribution in Canada and the United States had a chromosome complement of 2n ♀; ♂ = 20A + XO;XX. A detailed analysis of chromosome lengths and of the heterochromatin content and distribution in the karyotypes of the populations sampled revealed extreme endophenotypic stability and conservatism. Two populations were found to contain heterochromatically variant karyomorphs, one being polymorphic with respect to a complex pattern of autosome and sex-chromosome heterochromatin expression, the other for the occurrence of a large heterochromatic supernumerary chromosome. The cytogenetic system of Boonacris species was compared with those of the related, largely sympatric species Appalachia arcana and Dendrotettix quercus. The last two species have 2n ♀; ♂ = 22A + XO;XX but their complements show structural differences. The available evidence from a number of podismine species suggests that the forms with the lower chromosome number (i.e. 21 ♀; 22 ♂) may have originated from a common 'proto-Podisma' ancestor with 23 chromosomes (♀) via evolutionary loss or elimination of a small, unstable megameric pair. This dichotomy of major phyletic lineages and other cytogenetic evidence is discussed in relation to a phenetic classification of the tribe.

Unstable equilibrium and radiation defects in solids

A new type of point defect in solids genetically related with Frenkel's pairs which appears when there exists the instability zone of pair vacancy ( v) - interstitial atom ( i). It is shown that, at large instability zones typical of ‘loose’ crystalline structures, equilibrium concentration of unstable pairs i- v may exceed the concentration of usual Frenkel's pairs. In the example of the semiconducting crystals In 2Te 3 and Ga 2Te 3 having loose structure it is experimentally demonstrated that equilibrium point defects cannot be preserved by specimen quenching and that irradiation by large doses of high-energy particles does not result in stable radiation defects formation.

Spontaneous Recombination of Frenkel Pairs in Neutron‐Irradiated Solids

AbstractThe accumulation of Frenkel defects in neutron‐irradiated solids is studied using a simple model of a displacement cascade. The lowering of the damage rate by spontaneous recombination of unstable Frenkel pairs is taken into account. The general equations are solved using the superposition approximation in which third‐order correlations are replaced by products of second‐order correlations. The saturation density of defects and the damage rate as a function of the density are calculated. By comparison with experiment the annealing and cascade volumes can be deduced for various metals.

On the Formation of Rapidly Rotating. Asteroids.

view Abstract Citations (1) References (5) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the Formation of Rapidly Rotating. Asteroids. Rabe, Eugene Abstract It is shown, on the basis of the energy integral of the lunar or stellar type of the three-body problem, that, in consequence of accretion and orbital friction relative to nebular matter, the development of dynamically unstable pairs of asteroid condensations into stable binary configurations would have been possible during the early formative period, before the dissipation of the solar nebula. Continued accretion and friction would have caused the components of such stable pairs to spiral in toward each other, until contact and the formation of one combined, rapidly rotating body was achieved. If the condensations had a density of 2.0 gm/cm3, the minimum period of rotation of asteroids formed in this manner would amount to about 4 7 hours, which is in close agreement with the observed periods Publication: The Astrophysical Journal Pub Date: January 1960 DOI: 10.1086/146824 Bibcode: 1960ApJ...131..231R full text sources ADS |