Laajakaistaliitynnät - xDSL-tekniikat ja muut vaihtoehdot

Tietoliikenteen suuria linjoja ovat mm. siirtonopeuksien kasvu, IP-tekniikan yleistyminen ja Internet-liitäntöjen kautta käytettävien palvelujen valtaisa lisääntyminen. Kotien verkkoliitännöissä eräänä haasteena on vielä tarjota kohtuullisilla kustannuksilla suuri liikennöintikapasiteetti, mikä voidaan tehdä usealla eri tavalla. Kotien laajakaistaiseen tulevaisuuteen johtaakin useita polkuja, joita tässä diplomityössä on kartoitettu. Työssä on esitelty erilaisia kotitalouksiin soveltuvia nopeita langallisia ja langattomia liitäntätekniikoita. Painopiste on nykyisessä valtavirrassa, kuparikaapelia käyttävässä xDSL-tekniikkaperheessä ja niihin pohjautuvissa verkoissa mukaan lukien ATM-pohjaiset runkoverkot Käytännön liitäntöjen laatua ja toimivuutta on selvitetty mittaamalla perinteistä ADSL-liitäntää sekä uudempaa tekniikkaa edustavaa SHDSL-liitäntää. Liittymiä mitattiin sekä xDSL-mittarilla että spektrianalysaattorilla. Mittauksissa kiinnitettiin huomiota kupariparien toimintaan, kuormituksen ja häiriöiden vaikutukseen sekä liittymän toimintaan käyttäjän kannalta. Mittauksissa todettiin, että kuparikaapeli sietää hyvin häiriöitä myös uusien tekniikoiden käytössä. Tulevaisuutta kartoitettiin haastattelututkimuksella, josta työhön on koostettu operaattoreiden, konsulttien ja käyttäjien näkemyksiä laajakaistaliitäntöjen ja niiden kautta saatavien palveluiden kehittymisestä. Tehty tutkimus osoittaa, että ADSL-tekniikka hyödyntää hyvin sille varattuja taajuusalueita. SHDSL-tekniikassa voidaan lähettää ja vastaanottaa suuria datamääriä molempiin suuntiin.

Laajakaistainen Vivaldi-antennielementti

Diplomityössä suunniteltiin, rakennettiin ja mitattiin laajakaistainen antennielementti lineaariseen antenniryhmään. Elementti toimii mikroaaltoalueella, ja sen kaistanleveys on noin 4,8:1. Elementti koostuu kaksipuolisesta eksponentiaalisesti taperoidusta rakoantennista eli Vivaldi-antennista ja laajakaistaisesta siirtymästä liuskajohdosta kaksipuoliseen rakojohtoon. Elementin koko pienimmällä käyttötaajuudella on noin 0,31 lambda kertaa 0,34 lambda, josta antennitorven koko on vain noin 0,21 lambda kertaa 0,21 lambda. Elementti suunniteltiin HFSS-simulointiohjelman avulla ja rakennettiin kahdesta erillisestä piirilevystä puristamalla nämä yhteen alumiinisella kehyksellä. Mittauksilla varmistettiin elementin toiminta ja simulointien luotettavuus. Osoitettiin, että elementti voidaan suunnitella simulointiohjelman avulla ja rakentaa työssä käytetyllä tavalla. Osoitettiin myös, että tarvittavaa mitoitussimulointien määrää voidaan vähentää yhdistämällä erikseen mitoitetut rakoantenni ja siirtymä. Lisäksi simuloinnein osoitettiin, että elementti toimii myös ryhmässä ja että sen toimintaa voidaan parantaa kehyksen avulla.

Local Services in a Fourth Generation Mobile Network

Neljännen sukupolven mobiiliverkot kokoaa kaikki tietoliikenneverkot ja palvelut Internetin ympärille. Tämä mullistus muuttaa vanhat vertikaaliset tietoliikenneverkot joissa yhden tietoliikenneverkon palvelut ovat saatavissa vain kyseisen verkon päätelaitteille horisontaaliseksi malliksi jossa päätelaitteet käyttävät omaa verkkoansa pääsynä Internetin palveluihin. Tämä diplomityö esittelee idean paikallisista palveluista neljännen sukupolven mobiiliverkossa. Neljännen sukupolven mobiiliverkko yhdistää perinteiset televerkkojen palvelut ja Internet palvelut sekä mahdollistaa uuden tyyppisten palveluiden luonnin. TCP/IP protokollien ja Internetin evoluutio on esitelty. Laajakaistaiset, lyhyen kantaman radiotekniikat joita käytetään langattomana yhteytenä Internetiin on käsitelty. Evoluutio kohti neljännen sukupolven mobiiliverkkoja on kuvattu esittelemällä vanhat, nykyiset ja tulevat mobiiliverkot sekä niiden palvelut. Ennustukset palveluiden ja markkinoiden tulevaisuuden kehityksestä on käsitelty. Neljännen sukupolven mobiiliverkon arkkitehtuuri mahdollistaa paikalliset palvelut jotka ovat saatavilla vain yhdessä paikallisessa 4G verkossa. Paikalliset palvelut voidaan muunnella jokaiselle käyttäjälle erikseen käyttäen profiili-informaatiota ja paikkatietoa. Työssä on pohdittu paikallisten palveluiden käyttökelpoisuutta ja mahdollisuuksia käyttäen Lappeenrannan teknillisen korkeakoulun 4G projektin palvelupilotin tuloksia.

Antennimittausjärjestelmän toteutus ja ominaisuuksien määrittäminen

Diplomityössä tarkasteltiin antennien säteilykuviomittauksiin käytettävien antennimittaratojen ominaisuuksia. Sovelletun elektroniikan laboratorion antennimittaradasta kehitettiin toimiva säteilykuvion mittausjärjestelmä, johon kuuluvat radiokaiuton kammio, suuntauskoneisto ja antennikannakkeet, HP 8720D -piirianalysaattori ja RF-kaapelointi sekä valmistutetut mitta-antennitorvet. Työssä vertailtiin koaksiaalikaapeleita ja valittiin antennimittaukseen soveltuvat. 1,70–2,60 GHz:n taajuusalueen mittastandardiksi suunniteltiin torviantenni, jonka kaksi prototyyppiä valmistutettiin konetekniikan osastolla. Torviantennien ominaisuudet mitattiin. Antennimittaradan ominaisuudet ja soveltuvuus erilaisiin antennimittauksiin selvitettiin sekä teoreettisesti että mittauksin.

A new multidisciplinary home care telemedicine system to monitor stable chronic human immunodeficiency virus-infected patients: a randomized study.

Background: Antiretroviral therapy has changed the natural history of human immunodeficiency virus (HIV) infection in developed countries, where it has become a chronic disease. This clinical scenario requires a new approach to simplify follow-up appointments and facilitate access to healthcare professionals. Methodology: We developed a new internet-based home care model covering the entire management of chronic HIV-infected patients. This was called Virtual Hospital. We report the results of a prospective randomised study performed over two years, comparing standard care received by HIV-infected patients with Virtual Hospital care. HIV-infected patients with access to a computer and broadband were randomised to be monitored either through Virtual Hospital (Arm I) or through standard care at the day hospital (Arm II). After one year of follow up, patients switched their care to the other arm. Virtual Hospital offered four main services: Virtual Consultations, Telepharmacy, Virtual Library and Virtual Community. A technical and clinical evaluation of Virtual Hospital was carried out. Findings: Of the 83 randomised patients, 42 were monitored during the first year through Virtual Hospital (Arm I) and 41 through standard care (Arm II). Baseline characteristics of patients were similar in the two arms. The level of technical satisfaction with the virtual system was high: 85% of patients considered that Virtual Hospital improved their access to clinical data and they felt comfortable with the videoconference system. Neither clinical parameters [level of CD4 + T lymphocytes, proportion of patients with an undetectable level of viral load (p = 0.21) and compliance levels 90% (p = 0.58)] nor the evaluation of quality of life or psychological questionnaires changed significantly between the two types of care. Conclusions: Virtual Hospital is a feasible and safe tool for the multidisciplinary home care of chronic HIV patients. Telemedicine should be considered as an appropriate support service for the management of chronic HIV infection.

Predictive ability of heel quantitative ultrasound for incident fractures: an individual-level meta-analysis.

UNLABELLED: The relationship between bone quantitative ultrasound (QUS) and fracture risk was estimated in an individual level data meta-analysis of 9 prospective studies of 46,124 individuals and 3018 incident fractures. Low QUS is associated with an increase in fracture risk, including hip fracture. The association with osteoporotic fracture decreases with time. INTRODUCTION: The aim of this meta-analysis was to investigate the association between parameters of QUS and risk of fracture. METHODS: In an individual-level analysis, we studied participants in nine prospective cohorts from Asia, Europe and North America. Heel broadband ultrasonic attenuation (BUA dB/MHz) and speed of sound (SOS m/s) were measured at baseline. Fractures during follow-up were collected by self-report and in some cohorts confirmed by radiography. An extension of Poisson regression was used to examine the gradient of risk (GR, hazard ratio per 1 SD decrease) between QUS and fracture risk adjusted for age and time since baseline in each cohort. Interactions between QUS and age and time since baseline were explored. RESULTS: Baseline measurements were available in 46,124 men and women, mean age 70 years (range 20-100). Three thousand and eighteen osteoporotic fractures (787 hip fractures) occurred during follow-up of 214,000 person-years. The summary GR for osteoporotic fracture was similar for both BUA (1.45, 95 % confidence intervals (CI) 1.40-1.51) and SOS (1.42, 95 % CI 1.36-1.47). For hip fracture, the respective GRs were 1.69 (95 % CI, 1.56-1.82) and 1.60 (95 % CI, 1.48-1.72). However, the GR was significantly higher for both fracture outcomes at lower baseline BUA and SOS (p < 0.001). The predictive value of QUS was the same for men and women and for all ages (p > 0.20), but the predictive value of both BUA and SOS for osteoporotic fracture decreased with time (p = 0.018 and p = 0.010, respectively). For example, the GR of BUA for osteoporotic fracture, adjusted for age, was 1.51 (95 % CI 1.42-1.61) at 1 year after baseline, but at 5 years, it was 1.36 (95 % CI 1.27-1.46). CONCLUSIONS: Our results confirm that quantitative ultrasound is an independent predictor of fracture for men and women particularly at low QUS values.

High mass microquasars and low latitude gamma-ray sources

Population studies of unidentified EGRET sources suggest that there exist at least three different populations of galactic gamma-ray sources. One of these populations is formed by young objects distributed along the galactic plane with a strong concentration toward the inner spiral arms of the Galaxy. Variability, spectral and correlation analysis indicate that this population is not homogeneous. In particular, there is a subgroup of sources that display clear variability in their gamma-ray fluxes on timescales from days to months. Following the proposal by Kaufman Bernad\'o et al. (2002), we suggest that this group of sources might be high-mass microquasars, i.e. accreting black holes or neutron stars with relativistic jets and early-type stellar companions. We present detailed inhomogeneous models for the gamma-ray emission of these systems that include both external and synchrotron self-Compton interactions. We have included effects of interactions between the jet and all external photon fields to which it is exposed: companion star, accretion disk, and hot corona. We make broadband calculations to predict the spectral energy distribution of these objects from radio up to GeV energies. The results and predictions can be tested by present and future gamma-ray instruments like INTEGRAL, AGILE, and GLAST.

Building an Access Network for Triple-Play Services

This final project was made for the Broadband department of TeliaSonera. This project gives an overview on how internet service provider might build an access network so that they can offer triple-play services. It also gives information on what equipment is needed and what is required from the access, aggregation and edge networks. The project starts by describing the triple-play service. Then it moves on to optical fiber cables, the network technology and network architecture. At the end of the project there is an example of the process and construction of the access network. It will give an overview of the total process and problems that a network planner might face during the planning phase of the project. It will give some indication on how one area is built from the start to finish. The conclusion of the project presents some points that must be taken into consideration when building an access network. The building of an access network has to be divided to a time span of eight to ten years, where one year is one phase in the project. One phase is divided into three parts; Selecting the areas and targets, Planning the areas and targets, and Documentation. The example area gives indication on the planning of an area. It is almost impossible to connect all targets at the same time. This means that the service provider has to complete the construction in two or three parts. The area is considered to be complete when more than 80% of the real estates have fiber.

Drosophila Ionotropic Receptor 25a mediates circadian clock resetting by temperature.

Circadian clocks are endogenous timers adjusting behaviour and physiology with the solar day. Synchronized circadian clocks improve fitness and are crucial for our physical and mental well-being. Visual and non-visual photoreceptors are responsible for synchronizing circadian clocks to light, but clock-resetting is also achieved by alternating day and night temperatures with only 2-4 °C difference. This temperature sensitivity is remarkable considering that the circadian clock period (~24 h) is largely independent of surrounding ambient temperatures. Here we show that Drosophila Ionotropic Receptor 25a (IR25a) is required for behavioural synchronization to low-amplitude temperature cycles. This channel is expressed in sensory neurons of internal stretch receptors previously implicated in temperature synchronization of the circadian clock. IR25a is required for temperature-synchronized clock protein oscillations in subsets of central clock neurons. Extracellular leg nerve recordings reveal temperature- and IR25a-dependent sensory responses, and IR25a misexpression confers temperature-dependent firing of heterologous neurons. We propose that IR25a is part of an input pathway to the circadian clock that detects small temperature differences. This pathway operates in the absence of known 'hot' and 'cold' sensors in the Drosophila antenna, revealing the existence of novel periphery-to-brain temperature signalling channels.

Universal Service Policies in Europe & Latam: Evidence on Bridging the Divide in Rural Areas

Broadband access is a key factor for economic and social development. However, providing broadband to rural areas is not attractive to private telecommunications operators due its low or zero investment return. To deal with broadband provision in rural areas, different governance systems based on private and public cooperation have appeared. This paper not only identifies and defines public and private cooperation models but also assesses their impact on overcoming the digital divide in rural areas. The results show that public ownership infrastructure under private management policy has had positive effects on reducing the broadband digital divide and being applied to areas with higher digital divide; subsides to private operators providers only positive effects on reducing broadband digital divide; but public infrastructure with public management programs did not. The results, obtained using quasi-experimental methods, suggest the importance of incentives and control mechanisms in broadband universal service provision plans.

The Evolution of the European Regulatory Framework for Electronic Communications

The paper reviews the historical transformation of the European regulatory framework for electronic communications from the era dominated by state-owned enterprises to the presence of regulated competition. In the course of these developments, the vision of the roles of the public and private sectors in electronic communications changed in expected and unexpected ways. While the period is characterized by a shift toward less direct state intervention, the intensity of regulation has increased in many areas. Most recently, in the wake of the financial crisis, new forms of state intervention can be observed, including public investment in communications infrastructure and public-private partnerships. As a result of the reforms, Europe has been able to achieve major successes but it also suffered unanticipated setbacks compared to other regions. The European Union emerged as the global leader in mobile communications during the 1990s and was able to roll-out first-generation broadband access networks more rapidly than many of its peers. Recently, however, Europe as a whole has not performed as well in deploying next-generation networks and advanced mobile communications services. The paper offers a political-economic explanation for these developments and assesses their effects on the performance of the European electronic communications sector and the economy. From this analysis, the European model emerges as a unique institutional arrangement with peculiar advantages and disadvantages. Once these are recognized, sensible next steps to build the strengths while avoiding the weaknesses of the model can be seen more clearly.

Innovation and Regulation in ICT. Keys for Development

The expansion of broadband speed and coverage over IP technology, which extend over transport and terminal access networks, has increased the demand for applications and content which by being provided over it, uniformly give rise to convergence. These shifts in technologies and enterprise business models are giving rise to the necessity for changing the perspective and scope of the Universal Service and of the regulation frameworks, with this last one based in the same principles as always but varying its application. Several aspects require special and renewed attention, such as the definition of relevant markets and dominant operators, the role of packages, interconnection of IP networks, network neutrality, the use of the spectrum with a vision of value for the citizenship, the application of the competition framework, new forms of licensing, treatment of the risk in the networks, changes in the regulatory authorities, amongst others. These matters are treated from the perspective of the actual trends in the world and its conceptual justification.

Nanoantenna enhanced emission of lightharvesting complex 2: the role of resonance, polarization, and radiative and non-radiative rates

Nanoantennae show potential for photosynthesis research for two reasons; first by spatially confining light for experiments which require high spatial resolution, and second by enhancing the photon emission of single light-harvesting complexes. For effective use of nanoantennae a detailed understanding of the interaction between the nanoantenna and the light-harvesting complex is required. Here we report how the excitation and emission of multiple purple bacterial LH2s (light-harvesting complex 2) are controlled by single gold nanorod antennae. LH2 complexes were chemically attached to such antennae, and the antenna length was systematically varied to tune the resonance with respect to the LH2 absorption and emission. There are three main findings. (i) The polarization of the LH2 emission is fully controlled by the resonant nanoantenna. (ii) The largest fluorescence enhancement, of 23 times, is reached for excitation with light at λ = 850 nm, polarized along the long antenna-axis of the resonant antenna. The excitation enhancement is found to be 6 times, while the emission efficiency is increased 3.6 times. (iii) The fluorescence lifetime of LH2 depends strongly on the antenna length, with shortest lifetimes of [similar]40 ps for the resonant antenna. The lifetime shortening arises from an 11 times resonant enhancement of the radiative rate, together with a 2–3 times increase of the non-radiative rate, compared to the off-resonant antenna. The observed length dependence of radiative and non-radiative rate enhancement is in good agreement with simulations. Overall this work gives a complete picture of how the excitation and emission of multi-pigment light-harvesting complexes are influenced by a dipole nanoantenna.

Factors influencing the evolution of e-commerce : an empirical analysis in a developed market economy

Peer-reviewed

Online and Offline Participation at the Local level: A Quantitative Analysis of the Catalan Municipalities

This article presents an analysis on local participatory experiences in Catalonia,both online and in-person. The analysis is based on a database set up by theauthors. The article carries out an explanatory analysis of local participatoryinitiatives (on- and offline) taking into account political variables (not usually con-sidered in this kind of analysis) and also classical socio-economic variables thatcharacterize municipalities. Hence, we add a quantitative analysis to the numerouscase studies on local e-participation experiences. We have chosen Catalonia becauseit is one of the European regions with more initiatives and a considerable localgovernment support for citizen participation initiatives since the 1980s. Thearticle offers a characterization of these experiences and an explanatory analysis,considering: (i) the institutional context in which these experiences are embedded,(ii) the citizen participation processes and mechanisms online and (iii) a set ofexplanatory variables composed of the population size and the province to whichthe municipality belongs, the political tendency of the mayor, the electoral absten-tion rate, age, income, level of education, broadband connection and users of theInternet in the municipality. The model that we present is explanatory for munici-palities with more than 20,000 inhabitants but it is not for fewer than 20,000inhabitants. Actually, the majority of these latter municipalities have not developedany participatory activities. Among all the variables, population size is the mostinfluential variable and affects the influence of other variables, such as the politicalparty of the mayor, the local abstention rate and the province.