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A study of DVB-T (Digital Video Broadcasting-Terrestrial) signal variability for indoor reception environments is stated in this paper. A commercial signal was measured and analyzed in order to obtain C/N threshold values that account time and space fluctuations. In this way, results increase the accuracy of the values provided by the ETSI (European Telecommunications Standards Institute) standard and other studies that assume static propagation channels. On the other hand, the fading influence due to people walking near the reception antenna has been proved as critical for correct reception. Characterization of this effect has been made in terms of its depth and duration. The results obtained results improve DVB-T network planning and could be also relevant for other technologies sharing similar frequencies and bandwidths. Index Terms--BER before Reed Solomon, C/N thresholds, channel propagation, DVB-T indoor portable reception, [ESR.sub.5], space variability, time variability.

The Lee method, which was recommended by the International Telecommunications Union (ITU) and the European Conference of Postal and Telecommunications Administrations (CEPT) to obtain the local mean values of the received signal along a route, was developed for a Rayleigh distribution in the ultrahigh-frequency (UHF) band. This paper describes the generalization of this method to any propagation channel and frequency band and describes the methodology to obtain the parameters involved. The Generalized Lee Method is based on field data samples, which allows estimating the mean values without the requirement of a priori knowing the distribution function that better fits the propagation channel. The accuracy in obtaining the averaging interval is also improved. The Generalized Lee Method is solved for ground-wave propagation at the medium-wave (MW) band, taking data from field trials of a Digital Radio Mondiale (DRM) transmission. The results show that the values considerably differ from those obtained for a Rayleigh channel and prove that the method allows the adequate differentiation of long-term and short-term signals. The Generalized Lee Method completes the results obtained by Lee and Parsons and makes better characterization of the spatial variability possible. Index Terms--Channel estimation, coverage prediction techniques, propagation models, signal variability.

This paper presents the results obtained from the first extensive field trials of Medium Wave DRM (Digital Radio Mondiale) simulcast, which were carried out in Mexico D.F.. The transmitted signal was composed of a 10 kHz bandwidth AM part at 1060 kHz and an adjacent 10 kHz bandwidth DRM part at 1070 kHz broadcasting the same audio contents and with a theoretically calculated back-off ratio of 16 dB at transmission. The results in this paper will be accompanied by a thorough description of the transmission network set up and also with the measurement system and measurement techniques. The data processing techniques are also included to give a meaningful interpretation of the final results. The conclusions of this work have focused on threshold values for AM and DRM correct reception, simulcast time variability, mutual analogue--digital SNR degradation and reception impairment analysis. The overall result of this work is a high reliability of the AM and DRM services in the difficult Medium Wave reception environments of Mexico D.F. Index Terms--AM, DRM, field trials, medium wave, simuleast and static reception.

This paper presents an up to date study on external noise levels in the medium wave band based on field trials carried out in Spain and Mexico during years 2004 and 2005 respectively. External noise levels predicted by the ITU-R P.372 recommendation are based on measurements carried out more than 30 years ago and no updated results for the medium wave band have been published in this time. An increment on these noise levels have been measured, which leads to a significant impact on the minimum usable field strength requirements for the broadcasting systems used in this frequency band, such as the new Digital Radio Mondiale (DRM) and In-Band/On-Channel (IBOC) systems. Index Terms--Field trials, medium wave band, noise, noise measurement.

Millington's field strength prediction method is analyzed under different simulation conditions on the basis of the results of a medium waveband (MW or medium wave band extends from 530 to 1600 kHz) digital radio mondiale (DRM) measurement campaign. Millington technique applies the reciprocity condition by simply averaging the forward and reverse field strength values. This simplified approach could be a source of field strength prediction error in the MW planning tools. Critical path features for the fulfillment of the reciprocity condition are identified and their influence on predicted values is stated. Reciprocity effect on the predictions error is evaluated by means of the difference between digital medium wave field strength measured values of certain critical selected paths, and the corresponding Millington's method predicted ones. It has been found that the prediction error can be as high as 15 dB when comparing Millington's method results and measurements but the simple reciprocity approach made by Millington procedure is not the most remarkable source of error. Index Terms--Digital radio mondiale (DRM), field strength prediction, ground wave, medium wave, Millington's method.

Traditional imaging with one-photon confocal microscopy and organic fluorophores poses several challenges for the visualization of vascular tissue, including autofluorescence, fluorophore crosstalk, and photobleaching. We studied human coronary arteries (HCAs) and mouse aortas with a modified immunohistochemical (IHC) 'en face' method using quantum dot (Qdot) bioconjugates and two-photon excitation laser scanning microscopy (TPELSM). We demonstrated the feasibility of multilabeling intimal structures by exciting multicolored Qdots with only one laser wavelength (750 nm). Detailed cell structures, such as the granular appearance of von Willebrand factor (VWF) and the subcellular distribution of endothelial nitric oxide synthase, were visualized using green dots (525 nm), even when the emission maximum of these Qdots overlapped that of tissue autofluorescence (510-520 nm). In addition, sensitive fluorescence quantification of vascular cell adhesion molecule 1 expression at areas of varying hemodynamics (intercostal branches vs. nonbranching areas) was performed in normal C57B1/6 mice. Finally, we took advantage of the photostability of Qdots and the inherent three-dimensional (3D) resolution of TPELSM to obtain large z-stack series without photobleaching. This innovative en face method allowed simple multicolor profiling, highly sensitive fluorescence quantitation, and 3D visualization of the vascular endothelium with excellent spatial resolution. This is a promising technique to define the spatial and temporal interactions of endothelial inflammatory markers and quantify the effects of different interventions on the endothelium. semiconductor nanocrystals; multiphoton microscopy; atherosclerosis; shear stress; vascular cell adhesion molecule 1

An electrostatic potential-based methodology is presented to study the nature of Lewis acid sites on molybdenum and ruthenium sulfides. The results obtained suggest that the presence of Lewis acid sites on the MoS2 particles can be the more energetically favorable sites on the S edges with 50% sulfur coverage.

This paper presents a field measurement campaign developed to study the influence of the special features of a Single Frequency Network (SFN) reception in the C/N thresholds applicable to portable DTV reception. The measurements presented here were performed inside coverage areas of the nation wide SFN which broadcasts DTV (COFDM 8 K mode) services in Spain. The aim of this paper is to present some network planning reference values for portable reception in urban environments where both multipath and multiple transmitter reception have to be taken into account to ensure a good quality of service. Index Terms--COFDM, digital terrestrial television, field measurement campaign, portable reception, receiver performance, single frequency network.

This paper presents the measurement results obtained in an extensive field test campaign developed in two large cities of Spain (Madrid and Bilbao) with the aim of characterizing the portable outdoor reception of digital terrestrial television (COFDM) and continue the studies carried out by the authors during the past years [1], [2]. Index Terms--Digital terrestrial television, measurement campaign, portable reception.

A topologic study of the laplacian of the electronic density of selected (100) and (111) surfaces is carried out in order to study the effect of the surfaces Ru sulfur coordination number and of the surfaces S-H and Ru-H species into the thiophene adsorption on RuS(sub 2). The results suggest that a nonbonded local charge concentration on the S atom of the thiophene interacts with a local minimum on the outermost Ru atoms of the surfaces.

This paper presents the field trials and the coverage measurements carried out in urban areas in the first experimental terrestrial DAB (T-DAB) network at L-Band in Spain. The trials focused on obtaining the parameters that characterize the propagation channel for different urban environments. The results will be discussed taking into consideration recommended parameters and values given by international organizations (ITU-R, ETSI) as well as the ones obtained in former experimental networks worldwide. Index Terms--Digital audio broadcasting (DAB), Eureka 147, L-band, minimum C/N, scale factors CRC, urban areas.

The Laplacian of the electronic charge density of 3d transition metals was investigated.

An investigation of the topology of the electron density of the face-centered cubic transition metals Ni, beta-Co, Pd, Rh, Cu, Ir, Ag, Au and Pt is presented. The crystal graph of these metals is the result of packing octahedra and tetrahedra.

Standard density functional theory methods of eopographic features of electrostatic potential have been used to study the binding between water and models of poly (ethylene oxide). Similar theoretical methodologies will be applied to analyze the competitive interaction of water and PEO.

Standard density functional theory methods of eopographic features of electrostatic potential have been used to study the binding between water and models of poly (ethylene oxide). Similar theoretical methodologies will be applied to analyze the competitive interaction of water and PEO.