2,230 research outputs found
Turnover of outer and inner membrane proteins of rat liver mitochondria
Recent reports on the properties and composition of outer and inner mitochondrial membranes suggest that outer and inner membranes of mitochondria are derived from different sources of the cell [l-3]. I
Electron beam induced radio emission from ultracool dwarfs
We present the numerical simulations for an electron-beam-driven and
loss-cone-driven electron-cyclotron maser (ECM) with different plasma
parameters and different magnetic field strengths for a relatively small region
and short time-scale in an attempt to interpret the recent discovered intense
radio emission from ultracool dwarfs. We find that a large amount of
electromagnetic field energy can be effectively released from the beam-driven
ECM, which rapidly heats the surrounding plasma. A rapidly developed
high-energy tail of electrons in velocity space (resulting from the heating
process of the ECM) may produce the radio continuum depending on the initial
strength of the external magnetic field and the electron beam current. Both
significant linear polarization and circular polarization of electromagnetic
waves can be obtained from the simulations. The spectral energy distributions
of the simulated radio waves show that harmonics may appear from 10 to
70 ( is the electron plasma frequency) in the
non-relativistic case and from 10 to 600 in the relativistic
case, which makes it difficult to find the fundamental cyclotron frequency in
the observed radio frequencies. A wide frequency band should therefore be
covered by future radio observations.Comment: 10 pages, 19 figures, accepted for publication in the Astrophysical
Journa
Statistical Communication Theory
Contains reports on eleven research projects.National Institutes of Health (Grant MH-04737-03)National Science Foundation (Grant G-16526)National Aeronautics and Space Administration (Grant NsG-496
A comparative study using an autostereoscopic display with augmented and virtual reality
Advances in display devices are facilitating the integration of stereoscopic visualization in our daily lives. However, autostereoscopic visualization has not been extensively exploited. In this paper, we present a system that combines Augmented Reality (AR) and autostereoscopic visualization. We also present the first study that compares different aspects using an autostereoscopic display with AR and VR, in which 39 children from 8 to 10 years old participated. In our study, no statistically significant differences were found between AR and VR. However, the scores were very high in nearly all of the questions, and the children also scored the AR version higher in all cases. Moreover, the children explicitly preferred the AR version (81%). For the AR version, a strong and significant correlation was found between the use of the autostereoscopic screen in games and seeing the virtual object on the marker. For the VR version, two strong and significant correlations were found. The first correlation was between the ease of play and the use of the rotatory controller. The second correlation was between depth perception and the game global score. Therefore, the combinations of AR and VR with autostereoscopic visualization are possibilities for developing edutainment systems for childrenThis work was funded by the Spanish APRENDRA project (TIN2009-14319-C02). We would like to thank the following for their contributions: AIJU, the "Escola d'Estiu" and especially Ignacio Segui, Juan Cano, Miguelon Gimenez, and Javier Irimia. This work would not have been possible without their collaboration. The ALF3D project (TIN2009-14103-03) for the autostereoscopic display. Roberto Vivo, Rafa Gaitan, Severino Gonzalez, and M. Jose Vicent, for their help. The children's parents who signed the agreement to allow their children to participate in the study. The children who participated in the study. The ETSInf for letting us use its facilities during the testing phase.Arino, J.; Juan Lizandra, MC.; Gil Gómez, JA.; Mollá Vayá, RP. (2014). A comparative study using an autostereoscopic display with augmented and virtual reality. Behaviour and Information Technology. 33(6):646-655. https://doi.org/10.1080/0144929X.2013.815277S646655336Azuma, R. T. (1997). A Survey of Augmented Reality. Presence: Teleoperators and Virtual Environments, 6(4), 355-385. doi:10.1162/pres.1997.6.4.355Blum, T.et al. 2012. Mirracle: augmented reality in-situ visualization of human anatomy using a magic mirror.In: IEEE virtual reality workshops, 4–8 March 2012, Costa Mesa, CA, USA. Washington, DC: IEEE Computer Society, 169–170.Botden, S. M. B. I., Buzink, S. N., Schijven, M. P., & Jakimowicz, J. J. (2007). Augmented versus Virtual Reality Laparoscopic Simulation: What Is the Difference? World Journal of Surgery, 31(4), 764-772. doi:10.1007/s00268-006-0724-yChittaro, L., & Ranon, R. (2007). Web3D technologies in learning, education and training: Motivations, issues, opportunities. Computers & Education, 49(1), 3-18. doi:10.1016/j.compedu.2005.06.002Dodgson, N. A. (2005). Autostereoscopic 3D displays. Computer, 38(8), 31-36. doi:10.1109/mc.2005.252Ehara, J., & Saito, H. (2006). Texture overlay for virtual clothing based on PCA of silhouettes. 2006 IEEE/ACM International Symposium on Mixed and Augmented Reality. doi:10.1109/ismar.2006.297805Eisert, P., Fechteler, P., & Rurainsky, J. (2008). 3-D Tracking of shoes for Virtual Mirror applications. 2008 IEEE Conference on Computer Vision and Pattern Recognition. doi:10.1109/cvpr.2008.4587566Fiala, M. (2007). Magic Mirror System with Hand-held and Wearable Augmentations. 2007 IEEE Virtual Reality Conference. doi:10.1109/vr.2007.352493Froner, B., Holliman, N. S., & Liversedge, S. P. (2008). A comparative study of fine depth perception on two-view 3D displays. Displays, 29(5), 440-450. doi:10.1016/j.displa.2008.03.001Holliman, N. S., Dodgson, N. A., Favalora, G. E., & Pockett, L. (2011). Three-Dimensional Displays: A Review and Applications Analysis. IEEE Transactions on Broadcasting, 57(2), 362-371. doi:10.1109/tbc.2011.2130930Ilgner, J. F. R., Kawai, T., Shibata, T., Yamazoe, T., & Westhofen, M. (2006). Evaluation of stereoscopic medical video content on an autostereoscopic display for undergraduate medical education. Stereoscopic Displays and Virtual Reality Systems XIII. doi:10.1117/12.647591Jeong, J.-S., Park, C., Kim, M., Oh, W.-K., & Yoo, K.-H. (2011). Development of a 3D Virtual Laboratory with Motion Sensor for Physics Education. Ubiquitous Computing and Multimedia Applications, 253-262. doi:10.1007/978-3-642-20975-8_28Jones, J. A., Swan, J. E., Singh, G., Kolstad, E., & Ellis, S. R. (2008). The effects of virtual reality, augmented reality, and motion parallax on egocentric depth perception. Proceedings of the 5th symposium on Applied perception in graphics and visualization - APGV ’08. doi:10.1145/1394281.1394283Juan, M. C., & Pérez, D. (2010). Using augmented and virtual reality for the development of acrophobic scenarios. Comparison of the levels of presence and anxiety. Computers & Graphics, 34(6), 756-766. doi:10.1016/j.cag.2010.08.001Kaufmann, H., & Csisinko, M. (2011). Wireless Displays in Educational Augmented Reality Applications. Handbook of Augmented Reality, 157-175. doi:10.1007/978-1-4614-0064-6_6Kaufmann, H., & Meyer, B. (2008). Simulating educational physical experiments in augmented reality. ACM SIGGRAPH ASIA 2008 educators programme on - SIGGRAPH Asia ’08. doi:10.1145/1507713.1507717Konrad, J. (2011). 3D Displays. Optical and Digital Image Processing, 369-395. doi:10.1002/9783527635245.ch17Konrad, J., & Halle, M. (2007). 3-D Displays and Signal Processing. IEEE Signal Processing Magazine, 24(6), 97-111. doi:10.1109/msp.2007.905706Kwon, H., & Choi, H.-J. (2012). A time-sequential mutli-view autostereoscopic display without resolution loss using a multi-directional backlight unit and an LCD panel. Stereoscopic Displays and Applications XXIII. doi:10.1117/12.907793Livingston, M. A., Zanbaka, C., Swan, J. E., & Smallman, H. S. (s. f.). Objective measures for the effectiveness of augmented reality. IEEE Proceedings. VR 2005. Virtual Reality, 2005. doi:10.1109/vr.2005.1492798Monahan, T., McArdle, G., & Bertolotto, M. (2008). Virtual reality for collaborative e-learning. Computers & Education, 50(4), 1339-1353. doi:10.1016/j.compedu.2006.12.008Montgomery, D. J., Woodgate, G. J., Jacobs, A. M. S., Harrold, J., & Ezra, D. (2001). Performance of a flat-panel display system convertible between 2D and autostereoscopic 3D modes. Stereoscopic Displays and Virtual Reality Systems VIII. doi:10.1117/12.430813Morphew, M. E., Shively, J. R., & Casey, D. (2004). Helmet-mounted displays for unmanned aerial vehicle control. Helmet- and Head-Mounted Displays IX: Technologies and Applications. doi:10.1117/12.541031Pan, Z., Cheok, A. D., Yang, H., Zhu, J., & Shi, J. (2006). Virtual reality and mixed reality for virtual learning environments. Computers & Graphics, 30(1), 20-28. doi:10.1016/j.cag.2005.10.004Petkov, E. G. (2010). Educational Virtual Reality through a Multiview Autostereoscopic 3D Display. Innovations in Computing Sciences and Software Engineering, 505-508. doi:10.1007/978-90-481-9112-3_86Shen, Y., Ong, S. K., & Nee, A. Y. C. (2011). Vision-Based Hand Interaction in Augmented Reality Environment. International Journal of Human-Computer Interaction, 27(6), 523-544. doi:10.1080/10447318.2011.555297Swan, J. E., Jones, A., Kolstad, E., Livingston, M. A., & Smallman, H. S. (2007). Egocentric depth judgments in optical, see-through augmented reality. IEEE Transactions on Visualization and Computer Graphics, 13(3), 429-442. doi:10.1109/tvcg.2007.1035Urey, H., Chellappan, K. V., Erden, E., & Surman, P. (2011). State of the Art in Stereoscopic and Autostereoscopic Displays. Proceedings of the IEEE, 99(4), 540-555. doi:10.1109/jproc.2010.2098351Zhang, Y., Ji, Q., and Zhang, W., 2010. Multi-view autostereoscopic 3D display.In: International conference on optics photonics and energy engineering, 10–11 May 2010, Wuhan, China. Washington, DC: IEEE Computer Society, 58–61
Compensation of B-L charge of matter with relic sneutrinos
We consider massless gauge boson connected to B-L charge with and without
compensation to complete the investigation of the gauging of B and L charges.
Relic sneutrinos predicted by SUSY and composite models may compensate B-L
charge of matter. As a consequence of the possible compensation mechanism we
have shown that the available experimental data admit the range of the B-L
interaction constant, 10^{-29} < {\alpha}_{B-L} < 10^{-12}, in addition to
{\alpha}_{B-L} < 10^{-49} obtained without compensation.Comment: 6 page
Soft supersymmetry breaking terms from A4 lepton flavor symmetry
We study the supersymmetric model with the A4 lepton flavor symmetry, in
particular soft supersymmetry breaking terms, which are predicted from the A4
lepton flavor symmetry. We evaluate soft slepton masses and A-terms within the
framework of supergravity theory. Constraints due to experiments of flavor
changing neutral current processes are examined.Comment: minor modification, 17page
Transient study of the oxygen reduction reaction on reduced Pt and Pt alloys microelectrodes: evidence for the reduction of pre-adsorbed oxygen species linked to dissolved oxygen
Using chronoamperometry at preconditioned oxide-free Pt microdisc electrodes in aqueous media, we investigated the oxygen reduction reaction (ORR) on the millisecond timescale and obtained results consistent with the reduction of oxygen species which adsorb on the electrode before the ORR is electrochemically driven. Furthermore these adsorbed species are clearly linked to oxygen in solution. At long times, the amperometric response is solely controlled by the diffusion of dissolved oxygen towards the microelectrode. However, at short times, typically below 50 ms, the reduction of pre-adsorbed oxygen produces a large extra current whose magnitude depends on the oxygen concentration in solution, deliberate electrode poisoning and the rest time before the potential step. Using sampled current voltammetry we show that this extra current affects the entire potential range of the ORR. Using microdisc electrodes made with Pt alloys we find that the amperometric response is sufficiently sensitive to distinguish oxygen coverage differences between Pt, Pt0.9Rh0.1 and Pt0.9Ir0.1 microdiscs. These unexpected and, to our knowledge, never previously reported results provide new insight into the oxygen reduction reaction on Pt. The existence over a wide potential range of irreversibly adsorbed oxygen species arising from dissolved oxygen and different from Pt oxide is particularly relevant to the development of oxygen reduction catalysts for low temperature fuel cells
Modelling the radio pulses of an ultracool dwarf
<b>Context:</b> Recently, unanticipated magnetic activity in ultracool dwarfs (UCDs, spectral classes later than M7) has emerged from a number of radio observations. The highly (up to 100%) circularly polarized nature and high brightness temperature of the emission have been interpreted as requiring an effective amplification mechanism of the high-frequency electromagnetic waves − the electron cyclotron maser instability (ECMI).
<p/><b>Aims:</b> We aim to understand the magnetic topology and the properties of the radio emitting region and associated plasmas in these ultracool dwarfs, interpreting the origin of radio pulses and their radiation mechanism.
<p/><b>Methods:</b> An active region model was built, based on the rotation of the UCD and the ECMI mechanism.
<p/><b>Results:</b> The high degree of variability in the brightness and the diverse profile of pulses can be interpreted in terms of a large-scale hot active region with extended magnetic structure existing in the magnetosphere of TVLM 513-46546. We suggest the time profile of the radio light curve is in the form of power law in the model. Combining the analysis of the data and our simulation, we can determine the loss-cone electrons have a density in the range of 1.25 × 105−5 × 105 cm-3 and temperature between 107 and 5 × 107 K. The active region has a size <1 RJup, while the pulses produced by the ECMI mechanism are from a much more compact region (e.g. ~0.007 RJup). A surface magnetic field strength of ≈7000 G is predicted.
<p/><b>Conclusions:</b> The active region model is applied to the radio emission from TVLM 513-46546, in which the ECMI mechanism is responsible for the radio bursts from the magnetic tubes and the rotation of the dwarf can modulate the integral of flux with respect to time. The radio emitting region consists of complicated substructures. With this model, we can determine the nature (e.g. size, temperature, density) of the radio emitting region and plasma. The magnetic topology can also be constrained. We compare our predicted X-ray flux with Chandra X-ray observation of TVLM 513-46546. Although the X-ray detection is only marginally significant, our predicted flux is significantly lower than the observed flux. Further multi-wavelength observations will help us better understand the magnetic field structure and plasma behavior on the ultracool dwarf
New high magnetic field phase of the frustrated chain compound LiCuVO
Magnetization of the frustrated chain compound LiCuVO, focusing
on high magnetic field phases, is reported. Besides a spin-flop transition and
the transition from a planar spiral to a spin modulated structure observed
recently, an additional transition was observed just below the saturation
field. This newly observed magnetic phase is considered as a spin nematic
phase, which was predicted theoretically but was not observed experimentally.
The critical fields of this phase and its dM/dH curve are in good agreement
with calculations performed in a microscopic model (M. E. Zhitomirsky and H.
Tsunetsugu, preprint, arXiv:1003.4096v2).Comment: 5 pages, 4 figure
Good Quantum Convolutional Error Correction Codes And Their Decoding Algorithm Exist
Quantum convolutional code was introduced recently as an alternative way to
protect vital quantum information. To complete the analysis of quantum
convolutional code, I report a way to decode certain quantum convolutional
codes based on the classical Viterbi decoding algorithm. This decoding
algorithm is optimal for a memoryless channel. I also report three simple
criteria to test if decoding errors in a quantum convolutional code will
terminate after a finite number of decoding steps whenever the Hilbert space
dimension of each quantum register is a prime power. Finally, I show that
certain quantum convolutional codes are in fact stabilizer codes. And hence,
these quantum stabilizer convolutional codes have fault-tolerant
implementations.Comment: Minor changes, to appear in PR
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