545 research outputs found
Relaxation dynamics of the Lieb-Liniger gas following an interaction quench: A coordinate Bethe-ansatz analysis
We investigate the relaxation dynamics of the integrable Lieb-Liniger model
of contact-interacting bosons in one dimension following a sudden quench of the
collisional interaction strength. The system is initially prepared in its
noninteracting ground state and the interaction strength is then abruptly
switched to a positive value, corresponding to repulsive interactions between
the bosons. We calculate equal-time correlation functions of the nonequilibrium
Bose field for small systems of up to five particles via symbolic evaluation of
coordinate Bethe-ansatz expressions for operator matrix elements between
Lieb-Liniger eigenstates. We characterize the relaxation of the system by
comparing the time-evolving correlation functions following the quench to the
equilibrium correlations predicted by the diagonal ensemble and relate the
behavior of these correlations to that of the quantum fidelity between the
many-body wave function and the initial state of the system. Our results for
the asymptotic scaling of local second-order correlations with increasing
interaction strength agree with the predictions of recent generalized
thermodynamic Bethe-ansatz calculations. By contrast, third-order correlations
obtained within our approach exhibit a markedly different power-law dependence
on the interaction strength as the Tonks-Girardeau limit of infinitely strong
interactions is approached.Comment: 19 pages, 10 figures. v3: Final version. Typos fixed, and other minor
change
Conicoid Mirrors
The first order equation relating object and image location for a mirror of
arbitrary conic-sectional shape is derived. It is also shown that the parabolic
reflecting surface is the only one free of aberration and only in the limiting
case of distant sources.Comment: 9 page
Time-Changed Fast Mean-Reverting Stochastic Volatility Models
We introduce a class of randomly time-changed fast mean-reverting stochastic
volatility models and, using spectral theory and singular perturbation
techniques, we derive an approximation for the prices of European options in
this setting. Three examples of random time-changes are provided and the
implied volatility surfaces induced by these time-changes are examined as a
function of the model parameters. Three key features of our framework are that
we are able to incorporate jumps into the price process of the underlying
asset, allow for the leverage effect, and accommodate multiple factors of
volatility, which operate on different time-scales
Location and arrangement of campaniform sensilla in Drosophila melanogaster
Sensory systems provide input to motor networks on the state of the body and environment. One such sensory system in insects is the campaniform sensilla (CS), which detect deformations of the exoskeleton arising from resisted movements or external perturbations. When physical strain is applied to the cuticle, CS external structures are compressed, leading to transduction in an internal sensory neuron. In Drosophila melanogaster, the distribution of CS on the exoskeleton has not been comprehensively described. To investigate CS number, location, spatial arrangement, and potential differences between individuals, we compared the front, middle, and hind legs of multiple flies using scanning electron microscopy. Additionally, we imaged the entire body surface to confirm known CS locations. On the legs, the number and relative arrangement of CS varied between individuals, and single CS of corresponding segments showed characteristic differences between legs. This knowledge is fundamental for studying the relevance of cuticular strain information within the complex neuromuscular networks controlling posture and movement. This comprehensive account of all D. melanogaster CS helps set the stage for experimental investigations into their responsivity, sensitivity, and roles in sensory acquisition and motor control in a light-weight model organism
Photo-CIDNP in the reaction center of the diatom Cyclotella meneghiniana observed by 13C MAS NMR
Solid state NMR/Biophysical Organic Chemistr
Functional polymorphisms of the brain serotonin synthesizing enzyme tryptophan hydroxylase-2
Many neuropsychiatric disorders are considered to be related to the dysregulation of brain serotonergic neurotransmission. Tryptophan hydroxylase-2 (TPH2) is the neuronal-specific enzyme that controls brain serotonin synthesis. There is growing genetic evidence for the possible involvement of TPH2 in serotonin-related neuropsychiatric disorders; however, the degree of genetic variation in TPH2 and, in particular, its possible functional consequences remain unknown. In this short review, we will summarize some recent findings with respect to the functional analysis of TPH2
Shared Genetic Etiology Between Alcohol Dependence and Major Depressive Disorder
The clinical comorbidity of alcohol dependence (AD) and
major depressive disorder (MDD) is well established,
whereas genetic factors influencing co-occurrence remain
unclear. A recent study using polygenic risk scores (PRS)
calculated based on the first-wave Psychiatric Genomics
Consortium MDD meta-analysis (PGC-MDD1) suggests a
modest shared genetic contribution to MDD and AD. Using a
(∼10 fold) larger discovery sample, we calculated PRS
based on the second wave (PGC-MDD2) of results, in a
severe AD case–control target sample. We found significant associations between AD disease status and MDD-PRS derived from both PGC-MDD2 (most informative
P-threshold=1.0, P=0.00063, R2=0.533%) and PGCMDD1
(P-threshold=0.2, P=0.00014, R2=0.663%) metaanalyses;
the larger discovery sample did not yield
additional predictive power. In contrast, calculating PRS in a MDD target sample yielded increased power when using
PGC-MDD2 (P-threshold=1.0, P=0.000038, R2=1.34%)
versus PGC-MDD1 (P-threshold=1.0, P=0.0013,
R2=0.81%). Furthermore, when calculating PGC-MDD2
PRS in a subsample of patients with AD recruited explicitly excluding comorbid MDD, significant associations were still found (n=331; P-threshold=1.0, P=0.042, R2=0.398%). Meanwhile, in the subset of patients in which MDD was not the explicit exclusion criteria, PRS predicted more variance (n=999; P-threshold=1.0, P=0.0003, R2=0.693%). Our findings replicate the reported genetic overlap between AD and MDD and also suggest the need for improved, rigorous phenotyping to identify true shared cross-disorder genetic factors. Larger target samples are needed to reduce noise and take advantage of increasing discovery sample size
Child developmental delay and socio-economic disadvantage in Australia: A longitudinal study
Socio-economic inequalities in adult and child health in Australia have been an issue of national concern. While a large body of data has discussed adult health, there have been relatively few Australian reports of socioeconomic inequalities in child health. This occurs in a context where there have been increases in the proportion of Australian children living in poverty and where there has been an increased interest in child developmental delay as an indicator of child health status. This paper reports the result of a longitudinal study of pregnancy outcomes and one indicator of child health, namely child developmental delay. Three indicators of socio-economic status (chronic socio-economic disadvantage, mother's education, family income) were used to predict child developmental delays observed some 5: years after the study commenced. Mothers who had the lowest socio-economic status (using any of the indicators) had substantially higher rates of children manifesting developmental delays
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