Motor simulation without motor expertise: enhanced corticospinal excitability in visually experienced dance spectators

The human “mirror-system” is suggested to play a crucial role in action observation and execution, and is characterized by activity in the premotor and parietal cortices during the passive observation of movements. The previous motor experience of the observer has been shown to enhance the activity in this network. Yet visual experience could also have a determinant influence when watching more complex actions, as in dance performances. Here we tested the impact visual experience has on motor simulation when watching dance, by measuring changes in corticospinal excitability. We also tested the effects of empathic abilities. To fully match the participants' long-term visual experience with the present experimental setting, we used three live solo dance performances: ballet, Indian dance, and non-dance. Participants were either frequent dance spectators of ballet or Indian dance, or “novices” who never watched dance. None of the spectators had been physically trained in these dance styles. Transcranial magnetic stimulation was used to measure corticospinal excitability by means of motor-evoked potentials (MEPs) in both the hand and the arm, because the hand is specifically used in Indian dance and the arm is frequently engaged in ballet dance movements. We observed that frequent ballet spectators showed larger MEP amplitudes in the arm muscles when watching ballet compared to when they watched other performances. We also found that the higher Indian dance spectators scored on the fantasy subscale of the Interpersonal Reactivity Index, the larger their MEPs were in the arms when watching Indian dance. Our results show that even without physical training, corticospinal excitability can be enhanced as a function of either visual experience or the tendency to imaginatively transpose oneself into fictional characters. We suggest that spectators covertly simulate the movements for which they have acquired visual experience, and that empathic abilities heighten motor resonance during dance observation

"Massless'' Spin-32\frac{3}{2} Fields in the de Sitter Space

In this paper, the ``massless" spin-$\frac{3}{2}$ fields in the de Sitter space are considered. This work is in the continuation of a previous paper devoted to the quantization of the de Sitter ``massive" spin-$\frac{3}{2}$ fields. Due to the appearance of gauge invariance and indefinite metric, the covariant quantization of the ``massless" spin-$\frac{3}{2}$ fields requires an indecomposable representation of the de Sitter group. The gauge fixing corresponding to the simplest Gupta-Bleuler structure is used, and gauge invariant field is discussed. The field equation is obtained by using the Casimir operator of the de Sitter group. The solutions are written in terms of the coordinate-independent de Sitter plane waves. Finally, the generalized two-point function is calculated.Comment: 18 pages, no figure, submitted in E. Phys. J. C. arXiv admin note: text overlap with arXiv:gr-qc/0608004 by other author

Double Relaxation via AdS/CFT

We exploit the AdS/CFT correspondence to investigate thermalization in an N=2 strongly coupled gauge theory including massless fundamental matter (quark). More precisely, we consider the response of a zero temperature state of the gauge theory under variation of an external electric field leading to a time-dependent current. The holographic dual of the above set-up is given by introducing a time-dependent electric field on the probe D7-brane embedded in an AdS_5 X S^5 background. In the dual gravity theory, due to a time-dependent electric field an apparent horizon forms on the brane which, according to AdS/CFT dictionary, is the counterpart of the thermalization process in the gauge theory. We classify different functions for time-dependent electric field and study their effect on the apparent horizon formation. In the case of pulse functions where the electric field varies from zero to zero, apart from non-equilibrium phase, we observe that two apparent horizons form on the brane. On the gauge theory side, it means that the state of the gauge theory experiences two different temperatures during the time evolution.Comment: 28 pages, 13 figures, published versio

Multi-objective portfolio optimization of mutual funds under downside risk measure using fuzzy theory

Mutual fund is one of the most popular techniques for many people to invest their funds where a professional fund manager invests people's funds based on some special predefined objectives; therefore, performance evaluation of mutual funds is an important problem. This paper proposes a multi-objective portfolio optimization to offer asset allocation. The proposed model clusters mutual funds with two methods based on six characteristics including rate of return, variance, semivariance, turnover rate, Treynor index and Sharpe index. Semivariance is used as a downside risk measure. The proposed model of this paper uses fuzzy variables for return rate and semivariance. A multi-objective fuzzy mean-semivariance portfolio optimization model is implemented and fuzzy programming technique is adopted to solve the resulted problem. The proposed model of this paper has gathered the information of mutual fund traded on Nasdaq from 2007 to 2009 and Pareto optimal solutions are obtained considering different weights for objective functions. The results of asset allocation, rate of return and risk of each cluster are also determined and they are compared with the results of two clustering methods

Low Complexity Adaptive Transmission Scheme for Cooperative Networks with Decode-and-Forward Relay

In this paper, we consider adaptive quadratic amplitude modulation (QAM) for a cooperative network consists of a source, one decode-and-forward (DF) relay and a destination which are single antenna systems. For increasing the spectral efficiency of the system, we use adaptive modulation method for data transmission. We propose a new adaptive modulation scheme which has less complexity than available schemes. Then, we analyze average spectral efficiency (ASE), average bit error performance (ABEP) and outage probability of the proposed scheme. Computer simulation results corroborate our theoretical relations; furthermore, it shows that our proposed scheme has the same performance as maximum spectral efficiency scheme (MSES) with much lower complexity and has better performance than some other schemes

Magnetic fields around evolved stars: further observations of H2_2O maser polarization

We aim to detect the magnetic field and infer its properties around four AGB stars using H$_2$O maser observations. The sample we observed consists of the following sources: the semi-regular variable RT Vir and the Mira variables AP Lyn, IK Tau, and IRC+60370. We observed the 6$_{1,6}-5_{2,3}$ H$_2$O maser rotational transition, in full-polarization mode, to determine its linear and circular polarization. Based on the Zeeman effect, one can infer the properties of the magnetic field from the maser polarization analysis. We detected a total of 238 maser features, in three of the four observed sources. No masers were found toward AP Lyn. The observed masers are all located between 2.4 and 53.0 AU from the stars. Linear and circular polarization was found in 18 and 11 maser features, respectively. We more than doubled the number of AGB stars in which magnetic field has been detected from H$_2$O maser polarization, as our results confirm the presence of fields around IK Tau, RT Vir and IRC+60370. The strength of the field along the line of sight is found to be between 47 and 331 mG in the H$_2$O maser region. Extrapolating this result to the surface of the stars, assuming a toroidal field ($\propto$ r$^{-1}$), we find magnetic fields of 0.3-6.9 G on the stellar surfaces. If, instead of a toroidal field, we assume a poloidal field ($\propto$ r$^{-2}$), then the extrapolated magnetic field strength on the stellar surfaces are in the range between 2.2 and $\sim$115 G. Finally, if a dipole field ($\propto$ r$^{-3}$) is assumed, the field strength on the surface of the star is found to be between 15.8 and $\sim$1945 G. The magnetic energy of our sources is higher than the thermal and kinetic energy in the H$_2$O maser region of this class of objects. This leads us to conclude that, indeed, magnetic fields probably play an important role in shaping the outflows of evolved stars. (abridged)Comment: 15 pages, 5 figures, 7 tables. Accepted for publication in A&

The effect of water salinity on growth and survival of Rutilus frisii kutum fingerlings

This research was carried out over a period of 60 days in the summer and autumn of 2005 in the Caspian Sea Aquaculture Research Station (Inland Water Aquaculture Research Center). Fingerlings of Rutilus frisii kutum weighting one gram were transferred to fiberglass 100 liter tanks each stocked with 35 fish. The fish were divided into five groups and treated with five treatments and three replicates including, fresh water, 4ppt, 6ppt, 8ppt, and 10ppt salinity by completely randomized design. We found that different salinities did not affect the mortality rate of the fish. Comparison of food conversion ratio (FCR), special growth rate (SGR) and weight gain (WG) between control and other treatments revealed a significant difference (P less than or equal to 0.05). We also found that the 4ppt treatment differed meaningfully with 8ppt and 10ppt treatments in terms of FCR, SGR and WG (P less than or equal to 0.05) and the same was true between 6ppt and 8ppt and 10ppt treatments for the FCR, SGR and WG. The results showed that the maximum and minimum weight gain were related to 10ppt treatment (mean 58.9 plus or minus 2.71) and control (mean 39.1 plus or minus 4.73) respectively. The minimum special growth rate (0.549 plus or minus 0.057) was referred to the control treatment and the maximum (0.772 plus or minus 0.028) was seen in 10ppt salinity .The minimum average FCR (3.93 plus or minus 0.122) was seen in 10ppt salinity and the maximum (5.6 plus or minus 0.601) was observed in the control treatment. According to the results, it is suggested that the optimal salinity for fingerlings with mean weight 1gr is 8ppt and 10ppt