EPL (Europhysics Letters)最新文献

{"title":"Has the Mediterranean Sea felt the March 11th, 2011, Mw 9.0 Tohoku-Oki earthquake?","authors":"A. Vecchio, M. Anzidei, V. Capparelli, V. Carbone, I. Guerra","doi":"10.1209/0295-5075/98/59001","DOIUrl":"https://doi.org/10.1209/0295-5075/98/59001","url":null,"abstract":"The possibility that the tsunami, generated as a consequence of the large Mw 9.0 Tohoku-Oki earthquake of March 11th 2011, could be recorded by the tide gauge stations located in the Mediterranean Sea has been investigated. We find two kinds of transient signatures which should be attributed to the far-field destabilizing effect of the tsunami on the usual tidal components: 1) the excitation of a broad spectrum of frequency fluctuations, superimposed to the diurnal and semidiurnal tidal components, 2) the change of amplitude of the low-frequency tidal components in the Mediterranean, related to the sea surface fluctuation perhaps caused by the direct transmission of the tsunami across Gibraltar.","PeriodicalId":171520,"journal":{"name":"EPL (Europhysics Letters)","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123576081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Giant negative group time delay by microwave adaptors","authors":"A. Carôt, H. Aichmann, G. Nimtz","doi":"10.1209/0295-5075/98/64002","DOIUrl":"https://doi.org/10.1209/0295-5075/98/64002","url":null,"abstract":"A Fabry-Perot–like interferometer with two microwaveguide adaptors as reflectors creates a passive dielectric medium with a negative group delay time due to polarization shift. In that case rectangular with circular waveguides are adapted. A rotational strain of the polarization vector by one of the adaptors is coupled with the excitation of a drastic negative group velocity. The adapted rectangular and circular waveguides have the same dispersion. The input rectangular waveguide mode is linearly polarized, whereas the basic mode of the adapted circular waveguide is circularly polarized. A 20 m long circular waveguide connects the input with the output adaptor. Experiments are reproduced in the frequency and in the time domain. A polarization turn of the two different handed reflected circular wave modes causes the observed negative group velocity.","PeriodicalId":171520,"journal":{"name":"EPL (Europhysics Letters)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121410107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"External field as the functional of inhomogeneous density and the density matrix functional approach","authors":"V. B. Bobrov, S. Trigger, Yu. P. Vlasov","doi":"10.1209/0295-5075/98/53002","DOIUrl":"https://doi.org/10.1209/0295-5075/98/53002","url":null,"abstract":"Based on the Hohenberg-Kohn lemma and the hypotheses of the density functional existence for the external-field potential, it is shown that the strict result of the density functional theory is the equation of the external-field potential as the density functional. This result leads to the impossibility of determining the inhomogeneous density in a given external field if the inhomogeneous density is not known a priori. The problem encountered is intimately associated with the absence of a regular procedure for determining the universal density functional. The result obtained shows the advantage of the density matrix functional theory which yields a correct description of the inhomogeneous electron system in both the ideal-gas approximation and the self-consistent Hartree-Fock approximation in contrast to the density functional theory.","PeriodicalId":171520,"journal":{"name":"EPL (Europhysics Letters)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122344668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"K-intercalated carbon systems: Effects of dimensionality and substrate","authors":"T. Kaloni, M. Upadhyay Kahaly, Y. Cheng, U. Schwingenschlögl","doi":"10.1209/0295-5075/98/67003","DOIUrl":"https://doi.org/10.1209/0295-5075/98/67003","url":null,"abstract":"Density functional theory is employed to investigate the electronic properties of K-intercalated carbon systems. Young's modulus indicates that the intercalation increases the intrinsic stiffness. For K-intercalated bilayer graphene on SiC(0001) the Dirac cone is maintained, whereas a trilayer configuration exhibits a small splitting at the Dirac point. Interestingly, in contrast to many other intercalated carbon systems, the presence of the SiC(0001) substrate does not suppress but rather enhances the charge carrier density. Reasonably high values are found for all systems, the highest carrier density for the bilayer. The band structure and electron-phonon coupling of free-standing K-intercalated bilayer graphene points to a high probability for superconductivity in this system.","PeriodicalId":171520,"journal":{"name":"EPL (Europhysics Letters)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124457322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat transport in multilayer abrupt graphene junctions modulated with convexity-shaped quantum structure","authors":"Xiaofang Peng, Xin-Jun Wang, Li-Qun Chen, Keqiu Chen","doi":"10.1209/0295-5075/98/56001","DOIUrl":"https://doi.org/10.1209/0295-5075/98/56001","url":null,"abstract":"By using the force-constant and elastic wave continuum models, we investigate the ballistic phonon transport and thermal conductance in multilayer zigzag graphene nanoribbon junctions modulated with convexity-shaped quantum structures at low temperatures. The results show that the convexity-shaped (T-shaped or H-shaped) quantum structure can enhance thermal conductance at very low temperatures. The enhancement originates from the increased attenuation length of the evanescent modes in convexity-shaped quantum structures. A brief analysis of these results is given.","PeriodicalId":171520,"journal":{"name":"EPL (Europhysics Letters)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115722498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reply to the Comment by Christopher Hall","authors":"M. Reyssat, L. Y. Sangne, E. A. van Nierop, H. Stone","doi":"10.1209/0295-5075/98/56004","DOIUrl":"https://doi.org/10.1209/0295-5075/98/56004","url":null,"abstract":"We thank C. Hall for the Comment on imbibition in other material contexts. Two different communities can consider some aspects of the same problem, but with different approaches and hopefully new insights. We recognize that we missed the rich literature from the soil physics and construction materials communities and thank C. Hall for his valuable description of past research. However, our letter concerns model systems, which lead to specific dynamics not documented as well in these other literatures. Specifically, in our paper, we consider two ideal porous systems that we describe with analytical models derived from classical assumptions. We consider only perfect wetting conditions realized by using silicon oil as the liquid and glass spheres as the material. These glass spheres constitute an ideal porous material by having wellcalibrated sizes and shapes. In the first part of our letter, we are interested in imbibition in two uniform porous layers and we identify conditions and times during which the wetting front in the second layer advances with a constant velocity, which is clearly an unusual dynamical response in imbibition phenomena. This condition is realized by using two-layer systems made of small beads (of diameter ds) over a given length s and then large beads (of diameter d ). We show that as the liquid penetrates into the second layer, there is a well-characterized distance in which the imbibition front advances linearly in time. This regime is due to localized viscous dissipation into the layer of small beads, which can dominate the dissipation in the layer of large beads. The condition ds d is essential to observe this regime over a sufficiently long time and cannot be observed otherwise. We note that this regime can be discerned in fig. 7 of [1], but is not described as a linear regime by the authors. One of the aims of our paper consisted of pointing out this particular regime, which is completely different from what is commonly accepted and is not well documented in the soil physics or other literatures, to the best of our knowledge. An interesting feature of this unusual linear regime is its possibility to be perfectly predicted by choosing the ratio of the bead diameters and the length of the initial layer made of the small beads (eq. (12) of our paper [2]). We think that this linear response can be useful in other contexts such as analytical sciences, for example. In the second part of our paper, we analyze another particular case of layered materials where the layers are not chosen arbitrarily but organized in a way that the gradient of permeability is approximately constant over the sample. The experimental results are compared to the analytical model, with both in dimensionless form, and very good agreement is observed. The case treated in our letter differs from the ones from refs. [3,4], in that we are able to find an analytical solution that is an excellent description of the results of our model experiments. To conclu","PeriodicalId":171520,"journal":{"name":"EPL (Europhysics Letters)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131852873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Towards a temporal network analysis of interactive WiFi users","authors":"Yan Zhang, Lin Wang, Yi-Qing Zhang, Xiang Li","doi":"10.1209/0295-5075/98/68002","DOIUrl":"https://doi.org/10.1209/0295-5075/98/68002","url":null,"abstract":"Complex networks are used to depict topological features of complex systems. The structure of a network characterizes the interactions among elements of the system, and facilitates the study of many dynamical processes taking place on it. In previous investigations, the topological infrastructure underlying dynamical systems is simplified as a static and invariable skeleton. However, this assumption cannot cover the temporal features of many time-evolution networks, whose components are evolving and mutating. In this letter, utilizing the log data of WiFi users in a Chinese university campus, we infuse the temporal dimension into the construction of dynamical human contact network. By quantitative comparison with the traditional aggregation approach, we find that the temporal contact network differs in many features, e.g., the reachability, the path length distribution. We conclude that the correlation between temporal path length and duration is not only determined by their definitions, but also influenced by the micro-dynamical features of human activities under certain social circumstance as well. The time order of individuals' interaction events plays a critical role in understanding many dynamical processes via human close proximity interactions studied in this letter. Besides, our study also provides a promising measure to identify the potential superspreaders by distinguishing the nodes functioning as the relay hub.","PeriodicalId":171520,"journal":{"name":"EPL (Europhysics Letters)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129670697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Validity of the HREELS surface dipole selection rule at semiconductor surfaces: Si(001)-(2×1)H/D","authors":"C. H. Patterson","doi":"10.1209/0295-5075/98/66001","DOIUrl":"https://doi.org/10.1209/0295-5075/98/66001","url":null,"abstract":"The surface loss function in the HREELS dipole scattering cross-section is calculated for Si(001)-(2×1)H and D surfaces using first-principles methods. Experimental spectra of these well-studied systems can only be explained if contributions from modes which induce polarization parallel to the surface are included. This relaxation of the surface dipole selection rule underlines the importance of first-principles calculations of vibrational spectral intensities at semiconductor surfaces.","PeriodicalId":171520,"journal":{"name":"EPL (Europhysics Letters)","volume":"2019 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115512519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of chaos on relativistic quantum tunneling","authors":"X. Ni, Liang Huang, Y. Lai, L. Pecora","doi":"10.1209/0295-5075/98/50007","DOIUrl":"https://doi.org/10.1209/0295-5075/98/50007","url":null,"abstract":"We solve the Dirac equation in two spatial dimensions in the setting of resonant tunneling, where the system consists of two symmetric cavities connected by a finite potential barrier. The shape of the cavities can be chosen to yield both regular and chaotic dynamics in the classical limit. We find that certain pointer states about classical periodic orbits can exist, which suppress quantum tunneling, and the effect becomes less severe as the underlying classical dynamics in the cavity is chaotic, leading to regularization of tunneling dynamics even in the relativistic quantum regime. Similar phenomena have been observed in graphene. A physical theory is developed to explain the phenomenon based on the spectrum of complex eigenenergies of the non-Hermitian Hamiltonian describing the effectively open cavity system.","PeriodicalId":171520,"journal":{"name":"EPL (Europhysics Letters)","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128142727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in the in- and out-of-plane magnetic susceptibility of YBCO crystals with temperature and hole content","authors":"I. Kokanović, J. Cooper, K. Iida","doi":"10.1209/0295-5075/98/57011","DOIUrl":"https://doi.org/10.1209/0295-5075/98/57011","url":null,"abstract":"We report new magnetic susceptibility and anisotropy data for single crystals of YBa2Cu3O6+x from x=0.38 to 0.95. We argue that the temperature (T) dependence of the magnetic anisotropy in the normal state well above Tc arises from a combination of the pseudogap and substantial g-factor anisotropy. With this interpretation we obtain onset temperatures for superconducting fluctuations over a wide range of x. For hole concentrations p<0.14 there are two extra contributions to the magnetic susceptibility and its anisotropy. We analyse these in terms of changes in the Van Vleck paramagnetism plus a significant paramagnetic contribution from an electron pocket at low fields in the region 0.084<p<0.135. This is where the superconducting transition temperature Tc(p) deviates from the usual parabolic law and where quantum oscillations and a negative Hall coefficient are observed.","PeriodicalId":171520,"journal":{"name":"EPL (Europhysics Letters)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116759972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}