An introduction to learning technology in tertiary education in the UK.

Contents: 1. The Learning Technology Arena 2. The Learning Technology Community 3. Learning Technology Tools 4. Key issues and developments in the Learning Technology Field 5. Implementing Learning Technologies 6. Further Resource

Measurement And Modeling Of Short Copper Cables For Ultra-wideband Communication

High-speed communication using the copper network, originally installed for telephony, is one of the dominant Internet access techniques. Several variants of a technology referred to as digital subscriber line (DSL) have been developed, standardized and installed during the last two decades. Essentially, DSL achieves high rates by exploiting wide bands of the copper cable channel. The shorter the cable, the wider the band that can be used efficiently for communication. Current DSL standards foresee the use of bands up to 30MHz. Cable properties have been studied by means of measurements, characterization and modeling up to frequencies of 30MHz. Recent investigations have shown that it is feasible both from technical and from economical point of view to exploit very short cables (up to 200m) even further and use bands above 30MHz. A prerequisite for further evaluation and the design of such ultra-wideband copper (UWBC) systems is the extension of existing cable models to higher frequencies. This paper presents wideband measurement results of insertion loss and crosstalk coupling in a 10-pair cable of various length values for frequencies up to 200MHz. We compare the results with extrapolations of cable models that are established in the 30MHz-range.6390Chen, W.Y., (1998) DSL: Simulation Techniques and Standards Development for Digital Subscriber Line Systems, , Macmillan Technical Publishing, ISBN 1-57870-017-5G.selt: Updated issues list for G.selt (2004) ITU-T Temporary Document SS U09, , ITU-TAsymmetric digital subscriber line (ADSL) transceivers (1999) ITU Recommendation G.992.1, , ITU-T, JuneAsymmetric digital subscriber line (ADSL) transceivers (1999) ITU Recommendation G.992.2, , ITU-T, JuneAsymmetric digital subscriber line (ADSL) extended bandwidth (ADSL2+) (2005) ITU Recommendation G.992.5, , ITU-TStarr, T., Cioffi, J.M., Silverman, P., (1998) Understanding Digital Subscriber Line Technology, , Prentice Hall, Englewood CliffsDedieu, H., The copper channel - Loop charactersitics and models (2005) Fundamentals of DSL Technology, , ch. ISBN 0849319137, AUERBACHVan Der Brink, R.F.M., (1998) Cable Reference Models for Simulating Metallic Access Networks, , Permanent Document TM6(97), ETSI STC TM6, Luleå, Sweden, JunePaul, C.R., (1994) Analysis of Multiconductor Transmission Lines, , Wiley, ISBN 0-471-02080-XCook, J.W., (1996) Parametric Modelling of Twisted Pair Cables for VDSL, , Temporary Document TD22, ETSI STC TM6, Vienna, Austria, MarVan Der Brink, R.F.M., (1997) Measurements and Models on Dutch Cables, , Temporary Document TD15, ETSI STC TM6, Tel Aviv, Israel, MarPollakowski, M., (1996) DTAG Cables Transmission Characteristics, , Temporary Document TD40, ETSI STC TM6, Vienna, Austria, MarPythoud, F., (1998) Model of Swiss Access Network Cables, , Temporary Document TD48, ETSI STC TM6, Madrid, Spain, JanHeylen, L., Musson, J., (1999) Cable Models Predict Physically Impossible Behavior in Time Domain, , Temporary Document TD08, ETSI STC TM6, Amsterdam, Netherlands, NovMusson, J., (1998) Maximum Likelihood Estimation of the Primary Parameters of Twisted Pair Cables, , Temporary Document TD06, ETSI STC TM6, Madrid, Spain, SeptBoets, P., Zekri, M., Van Biesen, L., Bostoen, T., Pollet, T., On the identification of cables for metallic access networks (2001) 18th IEEE Instrumentation and Measurement Technology Conference IMTC2001, 2, pp. 1348-1353. , Budapest, Hungary, MayBostoen, T., Boets, P., Zekri, M., Van Biesen, L., Pollet, T., Rabijns, D., Estimation of the transfer function of the access network by means of one-port scattering parameter measurements at the central office (2002) IEEE Journal on Selected Areas in Communication, 20, pp. 936-948. , JuneVery-high-bit-rate Digital Subscriber Line (VDSL) metallic interface part 1: Functional requirement and common specification (2001) T1E1.4/2000-009R3, , ANSI T1E1.4, FebVan Der Brink, R.F.M., (2001) Laboratory Performance Tests for XDSL Systems, , Permanent Document TM6(98)10, ETSI STC TM6, Sophia Antipolis, France, FebValenti, C., NEXT and FEXT models for twisted-pair North American loop plant (2002) IEEE Journal on Selected Areas in Communication, 20, pp. 893-900. , JuneNedev, N.H., McLaughlin, S., Cook, J.W., Wideband UTP cable measurements and modelling for MIMO systems (2004) Proc. European Signal Processing Conf. EUSIPCO 2004, , (Vienna, Austria), SeptMagesacher, T., Henkel, W., Tauböck, G., Nordström, T., Cable measurements supporting xDSL technologies (2002) Journal E&i Elektrotechnik und Informationstechnik, 199, pp. 37-43. , FebMagesacher, T., Ödling, P., Börjesson, P.O., Henkel, W., Nordström, T., Zukunft, R., Haar, S., On the capacity of the copper cable channel using the common mode (2002) Proc. IEEE Global Telecommun. Conf. GLOBECOM 2002, , (Taipei, Taiwan), NovTomita, N., Ohmura, M., Low-frequency crosstalk loss characteristics of balanced cables (1989) Electron. Commun. Japan, Part 1, 72 (3), pp. 95-105Goedbloed, J.J., Aspects of EMC at the equipment level (1997) Proc. 12th Intl. Symp. Electromagn. Compat., pp. 23-38. , (Zurich, Switzerland), FebWerner, J.J., The HDSL environment (1991) IEEE Journal on Selected Areas in Communication, 9, pp. 785-800. , AugConte, R.A., A crosstalk model for balanced digital transmission in multipair cables (1986) AT&T Tech. J., 65, pp. 41-59. , May-JunSchutt-Aine, J.E., High-frequency characterization of twisted-pair cables (2001) IEEE Trans. on Commun., 49, pp. 598-601. , AprGresh, P.A., Physical and transmission characteristics of customer loop plant (1969) The Bell System Technical Journal, 48, pp. 3337-3385. , DecManhire, L.M., Physical and transmission characteristics of customer loop plant (1978) The Bell System Technical Journal, 57, pp. 35-39. , JanPierce, S.B., Crosstalk in twisted pair circuits (1986) Proc. Intl. Wire and Cable Symp., pp. 349-354Fung, A., Lee, L.S., Falconer, D.D., A facility for near end crosstalk measurements on ISDN subscriber loops (1989) Proc. IEEE Global Telecommun. Conf, , paper 54.

Validación de métodos analíticos

In this paper we shall discuss the concept of method validation, describe the various elements and explain its close relationship with fitness for purpose. Method validation is based on the assumption that a series of requirements are fulfilled and we shall explain how these requirements are selected, the way in which evidence is supplied and what work has to be carried out in the laboratory. The basic principles of method validation and the different ways to validate a methodology, by inter-laboratory comparison or performing an in-house validation, are also described.En este artículo se discute el concepto de validación del método, se describen los elementos que la componen y se explica la fuerte relación entre la validación y las características de ajuste. El método de validación se basa en el cumplimiento de una serie de requerimientos, se explica como seleccionar esos requerimientos, la forma en que se suministran evidencias, y que trabajo se debe llevar a cabo en el laboratorio. También se describen, los principios básicos del método de validación y los diferentes caminos para validar una metodología, tanto en la comparación entre laboratorios o como cuando se lleva a cabo una validación dentro del laboratorio

Hospital and 4-year mortality predictors in patients with acute pulmonary edema with and without coronary artery disease

Long-term prognosis of acute pulmonary edema () remains ill defined. We evaluated demographic, echocardiographic, and angiographic data of 806 consecutive patients with with () and without coronary artery disease (non-) admitted from 2000 to 2010. Differences between hospital and long-term mortality and its predictors were also assessed. patients (n=638) were older and had higher incidence of diabetes and peripheral vascular disease than non- (n=168), and lower ejection fraction. Hospital mortality was similar in both groups (26.5% vs 31.5%; P =0.169) but recurrence was higher in patients (17.3% vs 6.5%; P <0.001). Age, admission systolic blood pressure, recurrence of , and need for inotropics or endotracheal intubation were the main independent predictors of hospital mortality. In contrast, overall mortality (70.0% vs 57.1%; P =0.002) and readmission for nonfatal heart failure after a 45-month follow-up (10-140; 17.3% vs 7.6%; P =0.009) were higher in than in non- patients. Age, peripheral vascular disease, and peak creatine kinase during index hospitalization, but not ejection fraction, were the main independent predictors of overall mortality, whereas coronary revascularization or valvular surgery were protective. These interventions were mostly performed during hospitalization index (294 of 307; 96%) and not intervened patients showed a higher risk profile. Long-term mortality in is high and higher in than in non- patients. Considering the different in-hospital and long-term mortality predictors herein described, which do not necessarily involve systolic function, it is conceivable that a more aggressive interventional program might improve survival in high-risk patients

Solid-state reference electrodes based on carbon nanotubes and polyacrylate membranes

A novel potentiometric solid-state reference electrode containing single-walled carbon nanotubes as the transducer layer between a polyacrylate membrane and the conductor is reported here. Single-walled carbon nanotubes act as an efficient transducer of the constant potentiometric signal originating from the reference membrane containing the Ag/AgCl/Cl− ions system, and they are needed to obtain a stable reference potentiometric signal. Furthermore, we have taken advantage of the light insensitivity of single-walled carbon nanotubes to improve the analytical performance characteristics of previously reported solid-state reference electrodes. Four different polyacrylate polymers have been selected in order to identify the most efficient reservoir for the Ag/AgCl system. Finally, two different arrangements have been assessed: (1) a solid-state reference electrode using photo-polymerised n-butyl acrylate polymer and (2) a thermo-polymerised methyl methacrylate:n-butyl acrylate (1:10) polymer. The sensitivity to various salts, pH and light, as well as time of response and stability, has been tested: the best results were obtained using single-walled carbon nanotubes and photo-polymerised n-butyl acrylate polymer. Water transport plays an important role in the potentiometric performance of acrylate membranes, so a new screening test method has been developed to qualitatively assess the difference in water percolation between the polyacrylic membranes studied. The results presented here open the way for the true miniaturisation of potentiometric systems using the excellent properties of single-walled carbon nanotubes

Vasa vasorum adventicials en pacients amb obesitat mòrbida: efecte de la cirurgia bariàtrica i relació amb la hipòxia nocturna

Introducció: La densitat dels vasa vasorum (VV) de l’adventícia carotídia és un marcador d’arterioesclerosi subclínica. S’estudia la influència de l’obesitat i el seu tractament sobre els VV, i la relació amb la síndrome d’apnees-hipoapnees del son (SAHS). Disseny: S’han realitzat tres estudis. Un compara els VV en 40 candidats a cirurgia bariàtrica (CB) i 40 controls. El segon compara els VV a l’any de la CB en 31 pacients. El tercer valora els VV i els resultats d’una poligrafia cardiorespiratòria en 31 pacients. Resultats: Els obesos tenen més VV que els controls. El diàmetre de cintura i la glucèmia s’hi associen de forma independent. Als 12 mesos de la CB els VV disminueixen, sense igualar-se al grup control. Hi ha correlació entre VV, índex d'apnea/hipoapnea (IAH) i percentatge de temps amb SaO2 < 90%, amb relació independent amb l'IAH. Conclusions: Aquestes dades ajuden a explicar l'augment de risc cardiovascular dels obesos, la seva millora després de la CB i l'increment del risc cardiovascular a la SAHS.Introducción: La densidad de vasa vasorum (VV) de la adventicia carotidea es un marcador de arterioesclerosis subclínica. Estudiamos la influencia de la obesidad y su tratamiento sobre los VV, y la relación con el síndrome de apneas-hipoapneas del sueño (SAHS). Diseño: Realizamos tres estudios. Uno compara los VV en 40 candidatos a cirugía bariátrica (CB) y 40 controles. El segundo compara los VV al año de la CB en 31 pacientes. El tercero valora los VV y los resultados de una poligrafía cardiorrespiratoria en 31 pacientes. Resultados: Los obesos tienen más VV que los controles. El diámetro de cintura y la glucemia se asocian independientemente a los VV. A los 12 meses de la CB los VV disminuyen, sin igualarse al grupo control. Hay correlación entre VV, índice de apnea/hipoapnea (IAH) y porcentaje de tiempo con SaO2 < 90%, con una relación independiente con el IAH. Conclusiones: Estos datos ayudan a explicar el aumento del riesgo cardiovascular en obesos, su mejoría después de la CB y el incremento de riesgo cardiovascular en el SAHS.Introduction: Vasa vasorum (VV) density in carotid adventitia is a marker of subclinical atherosclerosis. We study the influence on VV of obesity and its treatment and the relationship with sleep apnoea-hypoapnoea syndrome (SAHS). Design: There have been three studies performed. First, we compare VV in 40 candidates to bariatric surgery (BS), and 40 controls. Second, we compare VV one year after BS in 31 patients. Third, we address VV and the results of a cardiorespiratory polygraphy in 31 patients. Results: Obese have higher VV than controls. Waist diameter and plasma are independently associated to VV. One year after BS, VV decreased but without matching controls. There are correlations between VV and aopnea/hypoaopnea index (AHI) and the time percentage with O2 saturation < 90%, with an independent relation with AHI. Conclusions: Our data help to explain why obese have an increased cardiovascular risk, why it improves after BS and why there is an increased cardiovascular risk in SAHS

Vasa vasorum adventicials en pacients amb obesitat mòrbida: efecte de la cirurgia bariàtrica i relació amb la hipòxia nocturna

Introducció: La densitat dels vasa vasorum (VV) de l’adventícia carotídia és un marcador d’arterioesclerosi subclínica. S’estudia la influència de l’obesitat i el seu tractament sobre els VV, i la relació amb la síndrome d’apnees-hipoapnees del son (SAHS). Disseny: S’han realitzat tres estudis. Un compara els VV en 40 candidats a cirurgia bariàtrica (CB) i 40 controls. El segon compara els VV a l’any de la CB en 31 pacients. El tercer valora els VV i els resultats d’una poligrafia cardiorespiratòria en 31 pacients. Resultats: Els obesos tenen més VV que els controls. El diàmetre de cintura i la glucèmia s’hi associen de forma independent. Als 12 mesos de la CB els VV disminueixen, sense igualar-se al grup control. Hi ha correlació entre VV, índex d'apnea/hipoapnea (IAH) i percentatge de temps amb SaO2 < 90%, amb relació independent amb l'IAH. Conclusions: Aquestes dades ajuden a explicar l'augment de risc cardiovascular dels obesos, la seva millora després de la CB i l'increment del risc cardiovascular a la SAHS.Introducción: La densidad de vasa vasorum (VV) de la adventicia carotidea es un marcador de arterioesclerosis subclínica. Estudiamos la influencia de la obesidad y su tratamiento sobre los VV, y la relación con el síndrome de apneas-hipoapneas del sueño (SAHS). Diseño: Realizamos tres estudios. Uno compara los VV en 40 candidatos a cirugía bariátrica (CB) y 40 controles. El segundo compara los VV al año de la CB en 31 pacientes. El tercero valora los VV y los resultados de una poligrafía cardiorrespiratoria en 31 pacientes. Resultados: Los obesos tienen más VV que los controles. El diámetro de cintura y la glucemia se asocian independientemente a los VV. A los 12 meses de la CB los VV disminuyen, sin igualarse al grupo control. Hay correlación entre VV, índice de apnea/hipoapnea (IAH) y porcentaje de tiempo con SaO2 < 90%, con una relación independiente con el IAH. Conclusiones: Estos datos ayudan a explicar el aumento del riesgo cardiovascular en obesos, su mejoría después de la CB y el incremento de riesgo cardiovascular en el SAHS.Introduction: Vasa vasorum (VV) density in carotid adventitia is a marker of subclinical atherosclerosis. We study the influence on VV of obesity and its treatment and the relationship with sleep apnoea-hypoapnoea syndrome (SAHS). Design: There have been three studies performed. First, we compare VV in 40 candidates to bariatric surgery (BS), and 40 controls. Second, we compare VV one year after BS in 31 patients. Third, we address VV and the results of a cardiorespiratory polygraphy in 31 patients. Results: Obese have higher VV than controls. Waist diameter and plasma are independently associated to VV. One year after BS, VV decreased but without matching controls. There are correlations between VV and aopnea/hypoaopnea index (AHI) and the time percentage with O2 saturation < 90%, with an independent relation with AHI. Conclusions: Our data help to explain why obese have an increased cardiovascular risk, why it improves after BS and why there is an increased cardiovascular risk in SAHS

Gas phase molecular relaxation probed by synchrotron radiation experiments

This thesis presents experimental studies of gas phasemolecular relaxation after excitation with synchrotron photonsin the 15-35 eV and in the 70-350 eV regions. In the 15-35 eV region, molecular relaxation by neutraldissociation processes and non Franck-Condon effects in N2 and O2 molecules have beenstudied by means of dispersed fluorescence and photoelectronspectroscopy experimental techniques, respectively. From thedispersed fluorescence data, excitation functions for themeasured atomic fluorescence spectra have been obtained. Fromthe recorded photoelectron spectra vibrational branching ratioshave been produced. The results obtained reveal that Rydbergseries and singly and doubly excited valence states of theappropriate symmetry energetically accessible in the studiedregion and interactions between themaccount for most of theobserved effects in these two type of experiments. In the 70-350 eV range, molecular relaxation processesresulting in fragmentation of CD4 and SF6 after absorption ofsynchrotron light have been studied by energy resolved electronion coincidence technique using a multicoincidence experimentalstation developed by our group during the last five years forsuch type of experiments. The coincidence measurements yieldedmass spectra from which information about the kinematics of thedetected fragments has been deduced by means of Monte Carlosimulations of the experimental peak shapes. The obtainedresults show completely different dissociation patternsdepending on the molecular electronic states studied. Thesepatterns reflect the bonding properties of the excited orbitalsand they permit the description and in some cases theidentification of the different molecular relaxation pathwaysobserved. The achievements presented in this thesis exemplifythe potential of the multicoincidence station used in thereported experiments.NR 2014080