830 research outputs found
The influence of expertise on brain activation of the action observation network during anticipation of tennis and volleyball serves
In many daily activities, and especially in sport, it is necessary to predict the effects of others' actions in order to initiate appropriate responses. Recently, researchers have suggested that the action-observation network (AON) including the cerebellum plays an essential role during such anticipation, particularly in sport expert performers. In the present study, we examined the influence of task-specific expertise on the AON by investigating differences between two expert groups trained in different sports while anticipating action effects. Altogether, 15 tennis and 16 volleyball experts anticipated the direction of observed tennis and volleyball serves while undergoing functional magnetic resonance imaging (fMRI). The expert group in each sport acted as novice controls in the other sport with which they had only little experience. When contrasting anticipation in both expertise conditions with the corresponding untrained sport, a stronger activation of AON areas (SPL, SMA), and particularly of cerebellar structures, was observed. Furthermore, the neural activation within the cerebellum and the SPL was linearly correlated with participant's anticipation performance, irrespective of the specific expertise. For the SPL, this relationship also holds when an expert performs a domain-specific anticipation task. Notably, the stronger activation of the cerebellum as well as of the SMA and the SPL in the expertise conditions suggests that experts rely on their more fine-tuned perceptual-motor representations that have improved during years of training when anticipating the effects of others' actions in their preferred sport. The association of activation within the SPL and the cerebellum with the task achievement suggests that these areas are the predominant brain sites involved in fast motor predictions. The SPL reflects the processing of domain-specific contextual information and the cerebellum the usage of a predictive internal model to solve the anticipation task. © 2014 Balser, Lorey, Pilgramm, Naumann, Kindermann, Stark, Zentgraf, Williams and Munzert
Inelastic Interaction Corrections and Universal Relations for Full Counting Statistics
We analyze in detail the interaction correction to Full Counting Statistics
(FCS) of electron transfer in a quantum contact originating from the
electromagnetic environment surrounding the contact. The correction can be
presented as a sum of two terms, corresponding to elastic/inelastic electron
transfer. Here we primarily focus on the inelastic correction.
For our analysis, it is important to understand more general -- universal --
relations imposed on FCS only by quantum mechanics and statistics with no
regard for a concrete realization of a contact. So we derive and analyze these
relations. We reveal that for FCS the universal relations can be presented in a
form of detailed balance. We also present several useful formulas for the
cumulants.
To facilitate the experimental observation of the effect, we evaluate
cumulants of FCS at finite voltage and temperature. Several analytical results
obtained are supplemented by numerical calculations for the first three
cumulants at various transmission eigenvalues.Comment: 10 pages, 3 figure
Hydrodynamic approach to coherent nuclear spin transport
We develop a linear response formalism for nuclear spin diffusion in a
dipolar coupled solid. The theory applies to the high-temperature,
long-wavelength regime studied in the recent experiments of Boutis et al.
[Phys. Rev. Lett. 92, 137201 (2004)], which provided direct measurement of
interspin energy diffusion in such a system. A systematic expansion of Kubo's
formula in the flip-flop term of the Hamiltonian is used to calculate the
diffusion coefficients. We show that this approach is equivalent to the method
of Lowe and Gade [Phys. Rev. 156, 817 (1967)] and Kaplan [Phys. Rev. B 2, 4578
(1970)], but has several calculational and conceptual advantages. Although the
lowest orders in this expansion agree with the experimental results for
magnetization diffusion, this is not the case for energy diffusion. Possible
reasons for this disparity are suggested.Comment: 7 pages, REVTeX4; Published Versio
Phase Transitions in liquid Helium 3
The phase transitions of liquid Helium 3 are described by truncations of an
exact nonperturbative renormalization group equation. The location of the first
order transition lines and the jump in the order parameter are computed
quantitatively. At the triple point we find indications for partially universal
behaviour. We suggest experiments that could help to determine the effective
interactions between fermion pairs.Comment: 4 pages, 6 figures, LaTe
Potential stocks and increments of woody biomass in the European Union under different management and climate scenarios
BACKGROUND: Forests play an important role in the global carbon flow. They can store carbon and can also provide wood which can substitute other materials. In EU27 the standing biomass is steadily increasing. Increments and harvests seem to have reached a plateau between 2005 and 2010. One reason for reaching this plateau will be the circumstance that the forests are getting older. High ages have the advantage that they typical show high carbon concentration and the disadvantage that the increment rates are decreasing. It should be investigated how biomass stock, harvests and increments will develop under different climate scenarios and two management scenarios where one is forcing to store high biomass amounts in forests and the other tries to have high increment rates and much harvested wood.
RESULTS: A management which is maximising standing biomass will raise the stem wood carbon stocks from 30 tC/ha to 50 tC/ha until 2100. A management which is maximising increments will lower the stock to 20 tC/ha until 2100. The estimates for the climate scenarios A1b, B1 and E1 are different but there is much more effect by the management target than by the climate scenario. By maximising increments the harvests are 0.4 tC/ha/year higher than in the management which maximises the standing biomass. The increments until 2040 are close together but around 2100 the increments when maximising standing biomass are approximately 50 % lower than those when maximising increments. Cold regions will benefit from the climate changes in the climate scenarios by showing higher increments.
CONCLUSIONS: The results of this study suggest that forest management should maximise increments, not stocks to be more efficient in sense of climate change mitigation. This is true especially for regions which have already high carbon stocks in forests, what is the case in many regions in Europe. During the time span 2010-2100 the forests of EU27 will absorb additional 1750 million tC if they are managed to maximise increments compared if they are managed to maximise standing biomass. Incentives which will increase the standing biomass beyond the increment optimal biomass should therefore be avoided. Mechanisms which will maximise increments and sustainable harvests need to be developed to have substantial amounts of wood which can be used as substitution of non sustainable materials
Continuous virus inactivation using a packed-bed reactor
A critical unit operation in integrated continuous biomanufacturing is continuous virus inactivation. These reactors must provide sufficient minimum inactivation time and must have a narrow residence time. The narrow residence time is required to avoid a too short or too long incubation. Too short incubation may result in insufficient inactivation, too long may result in partial product destruction. We have developed a packed-bed continuous virus inactivation reactor (CVIR, Figure 1) with significant advantages over other continuous processing approaches, namely scalability, ease of operation and being truly continuous with undisrupted mass flow. The residence time distribution of our reactor is smaller compared to a coiled flow inverter or a jig in a box reactor.
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Design Considerations for the LHC 200 MHz RF System
The longitudinal beam transfer from the SPS into the LHC 400 MHz buckets will not be free of losses without a lower frequency capture system and a fast longitudinal damping system in LHC. We present a complete study of a combined system using four identical copper cavities at 200 MHz delivering 3 MV total CW voltage and having still enough bandwidth to achieve fast longitudinal damping. The shape of a cavity was designed according to the accelerating mode performance, its tuning and the higher order mode spectrum with respect to the LHC beam lines and their possible attenuation. The possibility to park the cavities during coast was included. The local heat load and the corresponding cooling water distribution as well as deformations were studied and techniques to build the cavity with all ports at low cost are proposed. The parameters of the RF generators, couplers and detuning are determined. Simulations of the total LHC RF system incorporating real delays, generator bandwidth and the control loops confirm that this system is capable of capturing and damping the beam longitudinally without losses
The LHC superconducting cavities
The LHC RF system, which must handle high intensity (0.5 A d.c.) beams, makes use of superconducting single-cell cavities, best suited to minimizing the effects of periodic transient beam loading. There will be eight cavities per beam, each capable of delivering 2 MV (5 MV/m accelerating field) at 400 MHz. The cavities themselves are now being manufactured by industry, using niobium-on-copper technology which gives full satisfaction at LEP. A cavity unit includes a helium tank (4.5 K operating temperature) built around a cavity cell, RF and HOM couplers and a mechanical tuner, all housed in a modular cryostat. Four-unit modules are ultimately foreseen for the LHC (two per beam), while at present a prototype version with two complete units is being extensively tested. In addition to a detailed description of the cavity and its ancillary equipment, the first test results of the prototype will be reported
Automatic Filters for the Detection of Coherent Structure in Spatiotemporal Systems
Most current methods for identifying coherent structures in
spatially-extended systems rely on prior information about the form which those
structures take. Here we present two new approaches to automatically filter the
changing configurations of spatial dynamical systems and extract coherent
structures. One, local sensitivity filtering, is a modification of the local
Lyapunov exponent approach suitable to cellular automata and other discrete
spatial systems. The other, local statistical complexity filtering, calculates
the amount of information needed for optimal prediction of the system's
behavior in the vicinity of a given point. By examining the changing
spatiotemporal distributions of these quantities, we can find the coherent
structures in a variety of pattern-forming cellular automata, without needing
to guess or postulate the form of that structure. We apply both filters to
elementary and cyclical cellular automata (ECA and CCA) and find that they
readily identify particles, domains and other more complicated structures. We
compare the results from ECA with earlier ones based upon the theory of formal
languages, and the results from CCA with a more traditional approach based on
an order parameter and free energy. While sensitivity and statistical
complexity are equally adept at uncovering structure, they are based on
different system properties (dynamical and probabilistic, respectively), and
provide complementary information.Comment: 16 pages, 21 figures. Figures considerably compressed to fit arxiv
requirements; write first author for higher-resolution version
Manipulation of photon statistics of highly degenerate chaotic radiation
Highly degenerate chaotic radiation has a Gaussian density matrix and a large
occupation number of modes . If it is passed through a weakly transmitting
barrier, its counting statistics is close to Poissonian. We show that a second
identical barrier, in series with the first, drastically modifies the
statistics. The variance of the photocount is increased above the mean by a
factor times a numerical coefficient. The photocount distribution reaches a
limiting form with a Gaussian body and highly asymmetric tails. These are
general consequences of the combination of weak transmission and multiple
scattering.Comment: 4 pages, 2 figure
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