4,534 research outputs found
Effective Theory of 3H and 3He
We present a new perturbative expansion for pionless effective field theory
with Coulomb interactions in which at leading order the spin-singlet
nucleon-nucleon channels are taken in the unitarity limit. Presenting results
up to next-to-leading order for the Phillips line and the neutron-deuteron
doublet-channel phase shift, we find that a perturbative expansion in the
inverse 1S0 scattering lengths converges rapidly. Using a new systematic
treatment of the proton-proton sector that isolates the divergence due to
one-photon exchange, we renormalize the corresponding contribution to the
3H-3He binding energy splitting and demonstrate that the Coulomb force in
pionless EFT is a completely perturbative effect in the trinucleon bound-state
regime. In our new expansion, the leading order is exactly isospin-symmetric.
At next-to-leading order, we include isospin breaking via the Coulomb force and
two-body scattering lengths, and find for the energy splitting
(E_B(3He)-E_B(3H))^NLO = (-0.86 +/- 0.17) MeV.Comment: 37 pages, 14 figures, published versio
Nuclear Physics Around the Unitarity Limit
We argue that many features of the structure of nuclei emerge from a strictly
perturbative expansion around the unitarity limit, where the two-nucleon S
waves have bound states at zero energy. In this limit, the gross features of
states in the nuclear chart are correlated to only one dimensionful parameter,
which is related to the breaking of scale invariance to a discrete scaling
symmetry and set by the triton binding energy. Observables are moved to their
physical values by small, perturbative corrections, much like in descriptions
of the fine structure of atomic spectra. We provide evidence in favor of the
conjecture that light, and possibly heavier, nuclei are bound weakly enough to
be insensitive to the details of the interactions but strongly enough to be
insensitive to the exact size of the two-nucleon system.Comment: 6 pages, 3 figures, published version, rewritten for clarit
On-demand Generation of Reduced Mechanisms based on Hierarchically Extended Intrinsic Low-Dimensional Manifolds in Generalized coordinates
APP Expression in Primary Neuronal Cell Cultures fromP6 Mice during in vitro Differentiation
Primary neuronal cell cultures from P6 mice were investigated in order to study amyloid protein precursor (APP) gene expression in differentiating neurons. Cerebellar granule cells which strongly express APP 695 allowed the identification of three distinct isoforms of neuronal APP 695. The high-molecular-weight form of APP 695 is sialylated. The expression pattern of neuronal APP 695 changes during in vitro differentiation. Sialylated forms become more abundant upon longer cultivation time. The secreted forms of sialylated, neuronal APP 695 are shown to comigrate with APP isolated from cerebrospinal fluid. We suggest that the different sialylation states of APP 695 may reflect the modulation of cell-cell and cell-substrate interactions during in vitro differentiation and regeneration
Investigation of the dynamical response of methane-air counterflow flames to inflow mixture composition and flow field perturbations
Cotunneling at resonance for the single-electron transistor
We study electron transport through a small metallic island in the
perturbative regime. Using a recently developed diagrammatic technique, we
calculate the occupation of the island as well as the conductance through the
transistor in forth order in the tunneling matrix elements, a process referred
to as cotunneling. Our formulation does not require the introduction of a
cut-off. At resonance we find significant modifications of previous theories
and good agreement with recent experiments.Comment: 5 pages, Revtex, 5 eps-figure
Indicators of stress in equitation
Stress is a generic concept describing the body’s reaction to external stimuli, including both physiological and psychological factors. Therefore, by definition, the assessment of psychological stress in the exercising horse encompasses the problem of teasing apart the psychological and physiological factors both of which result in stress responses. The present study reviews the existing literature on various measures of stress taken specifically in the context of equitation science. Particular attention has been paid to short-term effects, and commonly used measurements of short-term stress include heart rate, a number of heart rate variability parameters, blood or saliva cortisol levels, eye temperature, and various behaviour parameters including in particular behaviour patterns presumably indicative of conflict with the rider’s/trainer’s aids. Inspection of the individual studies’ results revealed that disagreement between these different measures of stress is commonplace. For physiological parameters, the largest proportion of agreement (i.e. both parameters simultaneously indicated either higher, insignificant or lower stress compared to a control treatment) was found for heart rate and heart rate variability parameters, while generally limited agreement was found for cortisol. It appears that cortisol levels may not be particularly useful for assessing/assessment of the valence of a situation in the exercising horse as cortisol levels are predominantly linked to activation and exercise levels. Although heart rate variability parameters reflect in theory more closely sympathovagal balance compared to cortisol levels, great care has to be taken regarding the use of appropriate time-frames, appropriate raw data correction methods as well as the use of appropriate equipment. In spite of its wide-spread and apparently successful use, popular equipment may in fact not be accurate enough under field conditions. Eye temperature is another promising parameter for assessment of psychological stress, but the technique is likewise susceptible to application errors. Given the high susceptibility of physiological parameters to errors at various experimental stages, behavioural rather than physiological parameters may in fact provide more accurate measures of valence when conducting experiments in the exercising horse. Behavioural parameters that appear to be particularly practical in assessing stress in ridden horses’ behaviour are associated with frequencies of behaviour indicative of conflict. However, while increased frequencies of are a good indicator of stress, the absence of conflict behaviour does not provide proof of the absence of stress due to the possible occurrence of conditions such as Learned Helplessness. In future studies, the above issues should be taken into consideration when designing experiments to assess psychological stress in ridden horses
Molecular Identification of Lactic Acid Bacteria Occurring in Must and Wine
A specifically amplified polymorphic DNA-polymerase chain reaction (SAPD-PCR), a molecularfingerprinting method based on the amplification of specific gene sequences, was applied in order to allowa rapid identification of lactic acid bacteria (LAB) occurring in must and wine. The applicability of thismethod was confirmed with isolated strains from different wine samples from the German wine growingregion Palatinate. In addition, the formation of biogenic amines by the isolated strains was studied. Morethan half of the bacterial isolates from 50 red and white wine samples were able to produce biogenic amines.General health concerns related to biogenic amines in must and wine underline the need for an identificationof these species. The majority of the isolated strains were assigned to the species Lactobacillus brevis. Themajor biogenic amines in the investigated wines which were detected by thin-layer chromatography andHPLC were tyramine, histamine and ethylamine
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