1,976 research outputs found
Low-energy three-body dynamics in binary quantum gases
The universal three-body dynamics in ultra-cold binary Fermi and Fermi-Bose
mixtures is studied. Two identical fermions of the mass and a particle of
the mass with the zero-range two-body interaction in the states of the
total angular momentum L=1 are considered. Using the boundary condition model
for the s-wave interaction of different particles, both eigenvalue and
scattering problems are treated by solving hyper-radial equations, whose terms
are derived analytically. The dependencies of the three-body binding energies
on the mass ratio for the positive two-body scattering length are
calculated; it is shown that the ground and excited states arise at and ,
respectively. For m/m_1 \alt \lambda_1 and m/m_1 \alt \lambda_2, the
relevant bound states turn to narrow resonances, whose positions and widths are
calculated. The 2 + 1 elastic scattering and the three-body recombination near
the three-body threshold are studied and it is shown that a two-hump structure
in the mass-ratio dependencies of the cross sections is connected with arising
of the bound states.Comment: 16 page
Twenty Years After the Velvet Revolution: Shifts in Czech Adolescents’ Perceptions of Family, School, and Society
Families and schools are traditionally seen as substantial socialization agents forming adolescents’ social values and their views of society. Special attention is paid to the question whether the relative importance of these influences remains stable in times of major social changes. In this study, two different generations of Czech middle adolescents are compared: (a) the “post-totalitarian” generation that grew up in the last decade of the communist regime and entered adolescence during the time of rapid political and socioeconomic changes (data collected in 1995) and (b) the current generation without personal experience with the communist regime, raised in a stable democratic society (data collected in 2010). Both groups of participants (total N = 2,127, aged from 14 to 17 years) were administered an identical questionnaire. First, we examined the changes in adolescents’ perception and evaluation of the society over the last 15 years. Today’s adolescents perceive society more as a community and their future orientations are more focused on materialistic and less on environmental values. While the emotional relationship between the children and parentsremains the same, adolescents learn a somewhat different message in the family, emphasizing self-reliance. School environment is perceived more as positive and engaging than 15 years ago. Second, we predicted adolescents’ social views and values from their assessment of family and school environment. Our results show that the effect of parental values on adolescents’ value orientations is higher in the current generation. Positive school environment contributes to the development of socially responsible orientations despite the changes in society
Evolution of spectral properties along the O(6)-U(5) transition in the interacting boson model. II. Classical trajectories
This article continues our previous study of level dynamics in the
[O(6)-U(5)]O(5) transition of the interacting boson model
[nucl-th/0504016] using the semiclassical theory of spectral fluctuations. We
find classical monodromy, related to a singular bundle of orbits with infinite
period at energy E=0, and bifurcations of numerous periodic orbits for E>0. The
spectrum of allowed ratios of periods associated with beta- and
gamma-vibrations exhibits an abrupt change around zero energy. These findings
explain anomalous bunching of quantum states in the E0 region, which
is responsible for the redistribution of levels between O(6) and U(5)
multiplets.Comment: 11 pages, 7 figures; continuation of nucl-th/050401
Threshold Laws for the Break-up of Atomic Particles into Several Charged Fragments
The processes with three or more charged particles in the final state exhibit
particular threshold behavior, as inferred by the famous Wannier law for (2e +
ion) system. We formulate a general solution which determines the threshold
behavior of the cross section for multiple fragmentation. Applications to
several systems of particular importance with three, four and five leptons
(electrons and positrons) in the field of charged core; and two pairs of
identical particles with opposite charges are presented. New threshold
exponents for these systems are predicted, while some previously suggested
threshold laws are revised.Comment: 40 pages, Revtex, scheduled for the July issue of Phys.Rev.A (1998
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Calculations and observations of the longitudinal instability caused by the ferrite inductors at the Los Alamos proton storage ring (PSR)
The frequency dependence of the complex permeability of the ferrite (at room temperature) used in the Inductors at PSR have been determined by comparing the S11 parameters of a jig containing a ferrite core, and a MAFIA simulation of the jig. Both the resonance frequency and the longitudinal impedance of the inductor were obtained by simulating the inductor cavity in MAFIA. Experimental observations of the longitudinal instability caused by the ferrite inductors at room temperature for both DC Coasting beams and Bunched Coasting beams at a variety of intensities have been conducted. Comparisons of observed and calculated growth times, thresholds, resonant frequencies, and width of the instability will be discussed
Universal description of the rotational-vibrational spectrum of three particles with zero-range interactions
A comprehensive universal description of the rotational-vibrational spectrum
for two identical particles of mass and the third particle of the mass
in the zero-range limit of the interaction between different particles is
given for arbitrary values of the mass ratio and the total angular
momentum . If the two-body scattering length is positive, a number of
vibrational states is finite for , zero for
, and infinite for . If the two-body scattering
length is negative, a number of states is either zero for or
infinite for . For a finite number of vibrational states, all the
binding energies are described by the universal function , where ,
,and is the vibrational
quantum number. This scaling dependence is in agreement with the numerical
calculations for and only slightly deviates from those for .
The universal description implies that the critical values and
increase as and ,
respectively, while a number of vibrational states for is
within the range
Three-Body Halos in Two Dimensions
A method to study weakly bound three-body quantum systems in two dimensions
is formulated in coordinate space for short-range potentials. Occurrences of
spatially extended structures (halos) are investigated. Borromean systems are
shown to exist in two dimensions for a certain class of potentials. An
extensive numerical investigation shows that a weakly bound two-body state
gives rise to two weakly bound three-body states, a reminiscence of the Efimov
effect in three dimensions. The properties of these two states in the weak
binding limit turn out to be universal.
PACS number(s): 03.65.Ge, 21.45.+v, 31.15.Ja, 02.60NmComment: 9 pages, 2 postscript figures, LaTeX, epsf.st
How quantum bound states bounce and the structure it reveals
We investigate how quantum bound states bounce from a hard surface. Our
analysis has applications to ab initio calculations of nuclear structure and
elastic deformation, energy levels of excitons in semiconductor quantum dots
and wells, and cold atomic few-body systems on optical lattices with sharp
boundaries. We develop the general theory of elastic reflection for a composite
body from a hard wall. On the numerical side we present ab initio calculations
for the compression of alpha particles and universal results for two-body
states. On the analytical side we derive a universal effective potential that
gives the reflection scattering length for shallow two-body states.Comment: final publication version, new lattice results on alpha particle
compression, 5 pages, 2 figure
Initial Quantitative Proteomic Map of 28 Mouse Tissues Using the SILAC Mouse
Identifying the building blocks of mammalian tissues is a precondition for understanding their function. In particular, global and quantitative analysis of the proteome of mammalian tissues would point to tissue-specific mechanisms and place the function of each protein in a whole-organism perspective. We performed proteomic analyses of 28 mouse tissues using high-resolution mass spectrometry and used a mix of mouse tissues labeled via stable isotope labeling with amino acids in cell culture as a "spike-in" internal standard for accurate protein quantification across these tissues. We identified a total of 7,349 proteins and quantified 6,974 of them. Bioinformatic data analysis showed that physiologically related tissues clustered together and that highly expressed proteins represented the characteristic tissue functions. Tissue specialization was reflected prominently in the proteomic profiles and is apparent already in their hundred most abundant proteins. The proportion of strictly tissue-specific proteins appeared to be small. However, even proteins with household functions, such as those in ribosomes and spliceosomes, can have dramatic expression differences among tissues. We describe a computational framework with which to correlate proteome profiles with physiological functions of the tissue. Our data will be useful to the broad scientific community as an initial atlas of protein expression of a mammalian species
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