982 resultados para Spread spectrum communication


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Globaalinen liiketoimintaympäristö on muutoksessa. Uudet teknologiat muuttavat toimintaympäristöä ja talouden säännöt muuttuvat nopeasti. Uusia liiketoimintamalleja tarvitaan. Tutkimuksen tavoitteena oli analysoida tieto- ja viestintäteollisuuden (ICT-teollisuus) nykytilannetta strategisesta ja kilpailuanalyyttisestä näkökulmasta, sekä luoda kuva ICT-teollisuudesta ja sen suurista pelureista Euroopassa ja USA:ssa. Tutkimus analysoi viittä suurta ICT-alan yritystä. Tutkimus oli luonteeltaan sekä kvalitatiivinen että kvantitatiivinen. Yrityksiä analysoitiin käyttäen numeerista ja laadullista materiaalia. Tutkimus perustui kirjallisuuteen, artikkeleihin, tutkimusraportteihin, yritysten internet-kotisivuihin ja vuosikertomuksiin. Tutkimuksen tuloksena voitiin löytää sekä yhtäläisyyksiä että eroavaisuuksia yritysten liiketoimintamallien ja taloudellisen menestymisen väliltä.

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Multicast is one method to transfer information in IPv4 based communication. Other methods are unicast and broadcast. Multicast is based on the group concept where data is sent from one point to a group of receivers and this remarkably saves bandwidth. Group members express an interest to receive data by using Internet Group Management Protocol and traffic is received by only those receivers who want it. The most common multicast applications are media streaming applications, surveillance applications and data collection applications. There are many data security methods to protect unicast communication that is the most common transfer method in Internet. Popular data security methods are encryption, authentication, access control and firewalls. The characteristics of multicast such as dynamic membership cause that all these data security mechanisms can not be used to protect multicast traffic. Nowadays the protection of multicast traffic is possible via traffic restrictions where traffic is allowed to propagate only to certain areas. One way to implement this is packet filters. Methods tested in this thesis are MVR, IGMP Filtering and access control lists which worked as supposed. These methods restrict the propagation of multicast but are laborious to configure in a large scale. There are also a few manufacturerspecific products that make possible to encrypt multicast traffic. These separate products are expensive and mainly intended to protect video transmissions via satellite. Investigation of multicast security has taken place for several years and the security methods that will be the results of the investigation are getting ready. An IETF working group called MSEC is standardizing these security methods. The target of this working group is to standardize data security protocols for multicast during 2004.

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Inherited peripheral neuropathies are a genetically heterogeneous group of disorders characterized by distal muscle weakness and sensory loss. Mutations in genes encoding aminoacyl-tRNA synthetases have been implicated in peripheral neuropathies, suggesting that these tRNA charging enzymes are uniquely important for the peripheral nerve. Recently, a mutation in histidyl-tRNA synthetase (HARS) was identified in a single patient with a late-onset, sensory-predominant peripheral neuropathy; however, the genetic evidence was lacking, making the significance of the finding unclear. Here, we present clinical, genetic, and functional data that implicate HARS mutations in inherited peripheral neuropathies. The associated phenotypic spectrum is broad and encompasses axonal and demyelinating motor and sensory neuropathies, including four young patients presenting with pure motor axonal neuropathy. Genome-wide linkage studies in combination with whole-exome and conventional sequencing revealed four distinct and previously unreported heterozygous HARS mutations segregating with autosomal dominant peripheral neuropathy in four unrelated families (p.Thr132Ile, p.Pro134His, p.Asp175Glu and p.Asp364Tyr). All mutations cause a loss of function in yeast complementation assays, and p.Asp364Tyr is dominantly neurotoxic in a Caenorhabditis elegans model. This study demonstrates the role of HARS mutations in peripheral neuropathy and expands the genetic and clinical spectrum of aminoacyl-tRNA synthetase-related human disease.

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During infection with human immunodeficiency virus (HIV), immune pressure from cytotoxic T-lymphocytes (CTLs) selects for viral mutants that confer escape from CTL recognition. These escape variants can be transmitted between individuals where, depending upon their cost to viral fitness and the CTL responses made by the recipient, they may revert. The rates of within-host evolution and their concordant impact upon the rate of spread of escape mutants at the population level are uncertain. Here we present a mathematical model of within-host evolution of escape mutants, transmission of these variants between hosts and subsequent reversion in new hosts. The model is an extension of the well-known SI model of disease transmission and includes three further parameters that describe host immunogenetic heterogeneity and rates of within host viral evolution. We use the model to explain why some escape mutants appear to have stable prevalence whilst others are spreading through the population. Further, we use it to compare diverse datasets on CTL escape, highlighting where different sources agree or disagree on within-host evolutionary rates. The several dozen CTL epitopes we survey from HIV-1 gag, RT and nef reveal a relatively sedate rate of evolution with average rates of escape measured in years and reversion in decades. For many epitopes in HIV, occasional rapid within-host evolution is not reflected in fast evolution at the population level.

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Since independent regulatory agencies (IRAs) became key actors in European regulatory governance in the 1990s, a significant share of policy-making has been carried out by organizations that are neither democratically elected nor directly accountable to elected politicians. In this context, public communication plays an important role. On the one hand, regulatory agencies might try to use communication to raise their accountability and thereby to mitigate their democratic deficit. On the other hand, communication may be used with the intent to steer the behavior of the regulated industry when more coercive regulatory means are unfeasible or undesirable. However, empirical research focusing directly on how regulators communicate is virtually non-existent. To fill this gap, this paper examines the public communication of IRAs in four countries (the United Kingdom, Germany, Ireland, and Switzerland) and three sectors (financial services, telecommunications, and broadcasting). The empirical analysis, based on qualitative interviews and a quantitative content analysis, indicates that the organization of the communication function follows a national pattern approach while a policy sector approach is helpful for understanding the use of communication as a soft tool of regulation.

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BACKGROUND: Variations in physical activity (PA) across nations may be driven by socioeconomic position. As national incomes increase, car ownership becomes within reach of more individuals. This report characterizes associations between car ownership and PA in African-origin populations across 5 sites at different levels of economic development and with different transportation infrastructures: US, Seychelles, Jamaica, South Africa, and Ghana. METHODS: Twenty-five hundred adults, ages 25-45, were enrolled in the study. A total of 2,101 subjects had valid accelerometer-based PA measures (reported as average daily duration of moderate to vigorous PA, MVPA) and complete socioeconomic information. Our primary exposure of interest was whether the household owned a car. We adjusted for socioeconomic position using household income and ownership of common goods. RESULTS: Overall, PA levels did not vary largely between sites, with highest levels in South Africa, lowest in the US. Across all sites, greater PA was consistently associated with male gender, fewer years of education, manual occupations, lower income, and owning fewer material goods. We found heterogeneity across sites in car ownership: after adjustment for confounders, car owners in the US had 24.3 fewer minutes of MVPA compared to non-car owners in the US (20.7 vs. 45.1 minutes/day of MVPA); in the non-US sites, car-owners had an average of 9.7 fewer minutes of MVPA than non-car owners (24.9 vs. 34.6 minutes/day of MVPA). CONCLUSIONS: PA levels are similar across all study sites except Jamaica, despite very different levels of socioeconomic development. Not owning a car in the US is associated with especially high levels of MVPA. As car ownership becomes prevalent in the developing world, strategies to promote alternative forms of active transit may become important.

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This thesis seeks to answer, if communication challenges in virtual teams can be overcome with the help of computer-mediated communication. Virtual teams are becoming more common work method in many global companies. In order for virtual teams to reach their maximum potential, effective asynchronous and synchronous methods for communication are needed. The thesis covers communication in virtual teams, as well as leadership and trust building in virtual environments with the help of CMC. First, the communication challenges in virtual teams are identified by using a framework of knowledge sharing barriers in virtual teams by Rosen et al. (2007) Secondly, the leadership and trust in virtual teams are defined in the context of CMC. The performance of virtual teams is evaluated in the case study by exploiting these three dimensions. With the help of a case study of two virtual teams, the practical issues related to selecting and implementing communication technologies as well as overcoming knowledge sharing barriers is being discussed. The case studies involve a complex inter-organisational setting, where four companies are working together in order to maintain a new IT system. The communication difficulties are related to inadequate communication technologies, lack of trust and the undefined relationships of the stakeholders and the team members. As a result, it is suggested that communication technologies are needed in order to improve the virtual team performance, but are not however solely capable of solving the communication challenges in virtual teams. In addition, suitable leadership and trust between team members are required in order to improve the knowledge sharing and communication in virtual teams.

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Coherent anti-Stokes Raman scattering is the powerful method of laser spectroscopy in which significant successes are achieved. However, the non-linear nature of CARS complicates the analysis of the received spectra. The objective of this Thesis is to develop a new phase retrieval algorithm for CARS. It utilizes the maximum entropy method and the new wavelet approach for spectroscopic background correction of a phase function. The method was developed to be easily automated and used on a large number of spectra of different substances.. The algorithm was successfully tested on experimental data.

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PURPOSE/OBJECTIVES: To survey oncology nurses and oncologists about difficulties in taking care of culturally and linguistically diverse patients and about interests in cross-cultural training.
. DESIGN: Descriptive, cross-sectional.
. SETTING: Web-based survey.
. SAMPLE: 108 oncology nurses and 44 oncologists. 
. METHODS: 31-item questionnaire derived from preexisting surveys in the United States and Switzerland.
. MAIN RESEARCH VARIABLES: Self-rated difficulties in taking care of culturally and linguistically diverse patients and self-rated interests in cross-cultural training.
. FINDINGS: All respondents reported communication difficulties in encounters with culturally and linguistically diverse patients. Respondents considered the absence of written materials in other languages, absence of a shared common language with patients, and sensitive subjects (e.g., end of life, sexuality) to be particularly problematic. Respondents also expressed a high level of interest in all aspects of cross-cultural training (task-oriented skills, background knowledge, reflexivity, and attitudes). Nurses perceived several difficulties related to care of migrants as more problematic than physicians did and were more interested in all aspects of cross-cultural training. 
. CONCLUSIONS: The need for cross-cultural training is high among oncology clinicians, particularly among nurses.
. IMPLICATIONS FOR NURSING: The results reported in the current study may help nurses in decision-making positions and educators in introducing elements of cross-cultural education into oncology curricula for nurses. Cross-cultural training should be offered to oncology nurses.

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The objective of the thesis was to explore the nature and characteristics of customer-related internal communication in a global industrial matrix organization during a specific customer relationship, and how it could be improved. The theoretical part of the study views the field of the concepts of intra-organizational information and knowledge sharing. The theoretical part also views the internal communications influences to customer relationships, its problematic, and the suggestions to improve internal communication in literature. The empirical part of the study was conducted with the Content Analysis and the Social Network Analysis as research methods. The data was collected by interviews and a questionnaire. Internal communication was observed first generally within the organization from the point of view of a certain business, and secondly, during a specific customer relationship at personal level and at departmental level. The results of the study describe the nature and characteristics of internal communication in the organization. The results give 13 suggestions for improving internal communication in the organization. Although the study has been done in one specific organization, it also offers insights for other organizations as well as managers to improve their internal communication.

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Objective: The aim of the current study was to investigate the long-term cognitive effects of electroconvulsive therapy (ECT) in a sample of adolescent patients in whom schizophrenia spectrum disorders were diagnosed. Methods: The sample was composed of nine adolescent subjects in whom schizophrenia or schizoaffective disorder was diagnosed according to DSM-IV-TR criteria on whom ECT was conducted (ECT group) and nine adolescent subjects matched by age, socioeconomic status, and diagnostic and Positive and Negative Syndrome Scale (PANSS) total score at baseline on whom ECT was not conducted (NECT group). Clinical and neuropsychological assessments were carried out at baseline before ECT treatment and at 2-year follow-up. Results: Significant differences were found between groups in the number of unsuccessful medication trials. No statistically significant differences were found between the ECT group and theNECT group in either severity as assessed by the PANSS, or in any cognitive variables at baseline.At follow-up, both groups showed significant improvement in clinical variables (subscales of positive, general, and total scores of PANSS and Clinical Global Impressions-Improvement). In the cognitive assessment at follow-up, significant improvement was found in both groups in the semantic category of verbal fluency task and digits forward. However, no significant differences were found between groups in any clinical or cognitive variable at follow-up. Repeated measures analysis found no significant interaction of time · group in any clinical or neuropsychological measures. Conclusions: The current study showed no significant differences in change over time in clinical or neuropsychological variables between the ECT group and the NECT group at 2-year follow-up. Thus, ECT did not show any negative influence on long-term neuropsychological variables in our sample.