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111.
112.
It is known that no length or time measurements are possible in sub-Planckian regions of spacetime. The Volovich hypothesis
postulates that the micro-geometry of spacetime may therefore be assumed to be non-archimedean. In this letter, the consequences
of this hypothesis for the structure, classification, and conformal symmetry of elementary particles, when spacetime is a
flat space over a non-archimedean field such as the p-adic numbers, is explored. Both the Poincaré and Galilean groups are treated. The results are based on a new variant of the
Mackey machine for projective unitary representations of semidirect product groups which are locally compact and second countable.
Conformal spacetime is constructed over p-adic fields and the impossibility of conformal symmetry of massive and eventually massive particles is proved. 相似文献
113.
Salla-Maarit Kokkonen Juha Nikkinen Jukka Remes Jussi Kantola Tuomo Starck Marianne Haapea Juho Tuominen Osmo Tervonen Vesa Kiviniemi 《Magnetic resonance imaging》2009
Analysis of resting-state functional magnetic resonance imaging (fMRI) data is based on detecting low-frequency signal fluctuations in functionally connected brain areas. These synchronous fluctuations in resting-state networks have been observed in several studies with healthy subjects. In this study, we explored if independent component analysis (ICA) can be used to localize the sensorimotor area from resting-state fMRI data in patients with brain tumors. Finger-tapping activation task and resting-state blood-oxygenation-level-dependent fMRI data were acquired from 8 patients with brain tumors and 10 healthy volunteers. Sensorimotor task independent components (ICtask) were used to verify resting-state independent components (ICrest) individually. In addition, sensorimotor ICrests were compared between the groups and no significant differences were detected in volume, spatial correlation or temporal correlation. These results show that it is possible to localize a sensorimotor area from resting-state data using ICA in patients with brain tumors. This offers a complementary method for assessing the sensorimotor area in subjects with brain tumors who have difficulties in performing motor paradigms. 相似文献
114.
We study theoretically current quantization in the charge turnstile based on the superconductor-normal-metal single-electron transistor. The quantization accuracy is limited by either Andreev reflection or by Cooper-pair-electron cotunneling. The rates of these processes are calculated in the "above-the-threshold" regime when they compete directly with the lowest-order tunneling. By shaping the ac gate voltage drive it should be possible to achieve the metrological accuracy of 10;{-8}, while maintaining the quantized current on the level of 30 pA, just by one turnstile with realistic parameters using aluminum as a superconductor. 相似文献
115.
Lehtonen JV Still DJ Rantanen VV Ekholm J Björklund D Iftikhar Z Huhtala M Repo S Jussila A Jaakkola J Pentikäinen O Nyrönen T Salminen T Gyllenberg M Johnson MS 《Journal of computer-aided molecular design》2004,18(6):401-419
BODIL is a molecular modeling environment geared to help the user to quickly identify key features of proteins critical to molecular recognition, especially (1) in drug discovery applications, and (2) to understand the structural basis for function. The program incorporates state-of-the-art graphics, sequence and structural alignment methods, among other capabilities needed in modern structure–function–drug target research. BODIL has a flexible design that allows on-the-fly incorporation of new modules, has intelligent memory management, and fast multi-view graphics. A beta version of BODIL and an accompanying tutorial are available at http://www.abo.fi/fak/mnf/bkf/research/johnson/bodil.html 相似文献
116.
Reynolds Stress Budgets in Couette and Boundary Layer Flows 总被引:1,自引:0,他引:1
Reynolds stress budgets for both Couette and boundary layer flows are evaluated and presented. Data are taken from direct
numerical simulations of rotating and non-rotating plane turbulent Couette flow and turbulent boundary layer with and without
adverse pressure gradient. Comparison of the total shear stress for the two types of flows suggests that the Couette case
may be regarded as the high Reynolds number limit for the boundary layer flow close to the wall. The limit values of turbulence
statistics close to the wall for the boundary layer for increasing Reynolds number approach the corresponding Couette flow
values. The direction of rotation is chosen so that it has a stabilizing effect, whereas the adverse pressure gradient is
destabilizing. The pressure-strain rate tensor in the Couette flow case is presented for a split into slow, rapid and Stokes
terms. Most of the influence from rotation is located to the region close to the wall, and both the slow and rapid parts are
affected. The anisotropy for the boundary layer decreases for higher Reynolds number, reflecting the larger separation of
scales, and becomes close to that for Couette flow. The adverse pressure gradient has a strong weakening effect on the anisotropy.
All of the data presented here are available on the web [36].
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
117.
M. Sc. Jukka Hassinen M. Sc. Ville Liljeström Prof. Mauri A. Kostiainen Prof. Robin H. A. Ras 《Angewandte Chemie (International ed. in English)》2015,54(27):7990-7993
Cationic gold nanoparticles offer intriguing opportunities as drug carriers and building blocks for self‐assembled systems. Despite major progress on gold nanoparticle research in general, the synthesis of cationic gold particles larger than 5 nm remains a major challenge, although these species would give a significantly larger plasmonic response compared to smaller cationic gold nanoparticles. Herein we present the first reported synthesis of cationic gold nanoparticles with tunable sizes between 8–20 nm, prepared by a rapid two‐step phase‐transfer protocol starting from simple citrate‐capped particles. These cationic particles form ordered self‐assembled structures with negatively charged biological components through electrostatic interactions. 相似文献
118.
Lehtonen HM Penttinen H Rauhala J Välimäki V 《The Journal of the Acoustical Society of America》2007,122(3):1787
This paper describes the main features of the sustain-pedal effect in the piano through signal analysis and presents an algorithm for simulating the effect. The sustain pedal is found to increase the decay time of partials in the middle range of the keyboard, but this effect is not observed in the case of the bass and treble tones. The amplitude beating characteristics of piano tones are measured with and without the sustain pedal engaged, and amplitude envelopes of partial overtone decay are estimated and displayed. It is found that the usage of the sustain pedal introduces interesting distortions of the two-stage decay. The string register response was investigated by removing partials from recorded tones; it was observed that as the string register is free to vibrate, the amount of sympathetic vibrations is increased. The synthesis algorithm, which simulates the string register, is based on 12 string models that correspond to the lowest tones of the piano. The algorithm has been tested with recorded piano tones without the sustain pedal. The objective and subjective results show that the algorithm is able to approximately reproduce the main features of the sustain-pedal effect. 相似文献
119.
Saira OP Meschke M Giazotto F Savin AM Möttönen M Pekola JP 《Physical review letters》2007,99(2):027203
We present experiments on a superconductor-normal-metal electron refrigerator in a regime where single-electron charging effects are significant. The system functions as a heat transistor; i.e., the heat flux out from the normal-metal island can be controlled with a gate voltage. A theoretical model developed within the framework of single-electron tunneling provides a full quantitative agreement with the experiment. This work serves as the first experimental observation of Coulombic control of heat transfer and, in particular, of refrigeration in a mesoscopic system. 相似文献
120.
Arja Sarpola Heikki Hellman Vesa Hietapelto Jorma Jalonen Jukka Jokela Jaakko Rämö Jaakko Saukkoriipi 《Polyhedron》2007
Hydrolysis and speciation of aluminium sulfate octadecahydrate Al2(SO4)3·18H2O was studied by electrospray time of flight mass spectrometry (ESI TOF MS). Several novel polymeric species were determined. Highly charged polymers, characterized by other methods, such as the Keggin cation [Al13O4(OH)24(H2O)12]7+ and the octameric aluminium hydroxide cluster [Al8(OH)14(H2O)18](SO4)5 16H2O, were found using ESI-MS as the anions [Al13O4(OH)25(SO4)4]2− and [Al8O(OH)14(SO4)5(H2O)4]2−. All the main species identified contained sulfate or hydrogen sulfate. The compositions of the determined ions mimicked those of several stable mineral forms. 相似文献