Broadband light emitters operation, which covers multiple wavelengths of the electromagnetic spectrum, has been established as an indispensable element to the human kind, continuously advancing the living standard by serving as sources in important multi-disciplinary field applications such as biomedical imaging and sensing, general lighting and internet and mobile phone connectivity. In general, most commercial broadband light sources relies on complex systems for broadband light generation which are bulky, and energy hungry. Recent demonstration of ultra-broadband emission from semiconductor light sources in the form of superluminescent light emitting diodes (SLDs) has paved way in realization of broadband emitters on a completely novel platform, which offered compactness, cost effectiveness, and comparatively energy efficient, and are already serving as a key component in medical imaging systems. The low power-bandwidth product is inherent in SLDs operating in the amplified spontaneous emission regime. A quantum leap in the advancement of broadband emitters, in which high power and large bandwidth (in tens of nm) are in demand. Recently, the birth of a new class of broadband semiconductor laser diode (LDs) producing multiple wavelength light in stimulated emission regime was demonstrated. This very recent manifestation of a high power-bandwidth-product semiconductor broadband LDs relies on interband optical transitions via quantum confined dot/dash nanostructures and exploiting the natural inhomogeneity of the self-assembled growth technology. This concept is highly interesting and extending the broad spectrum of stimulated emission by novel device design forms the central focus of this dissertation. In this work, a simple rate equation numerical technique for modeling InAs/InP quantum dash laser incorporating the properties of inhomogeneous broadening effect on lasing spectra was developed and discussed, followed by a comprehensive experimental analysis of a novel epitaxial structure design. The layered structure is based on chirping the barrier layer thickness of the over grown quantum dash layer, in a multi-stack quantum dash/barrier active region, with the aim of inducing additional inhomogeneity. Based on material-structure and device characterization, enhanced lasing-emission bandwidth is achieved from the narrow (2 u m)ridge-waveguide LDs as a result of the formation of multiple ensembles of quantum dashes that are electronically different, in addition to improved device performance. Moreover, realization of SLDs from this device structure demonstrated extra-ordinary emission bandwidth covering the entire international telecommunication union (O- to U-) bands. This accomplishment is a collective emission from quantum wells and quantum dashes of the device active region. All these results lead to a step forward in the eventual realization of more than 150 nm lasing bandwidth from a single semiconductor laser diode.

In this cross-sectional study, the sensibility, reliability, and validity of the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire were assessed in patients who underwent neck dissection for head and neck cancer. A sensibility questionnaire was used to assess face and content validity. Test-retest reliability was tested by re-mailing the questionnaire; validity, by evaluating differences in scores between patients undergoing different types of neck dissections and by correlating DASH scores with Neck Dissection Impairment Index (NDII) scores. The DASH was considered sensible by both patients and surgeons. The DASH was reliable with an intraclass coefficient of 0.91. The DASH showed differences between patients who underwent accessory nerve-sacrifice and nerve-sparing neck dissection. DASH scores strongly correlated with NDII scores. Thus, the DASH is a sensible, reliable, and valid instrument for assessing shoulder impairments and activity limitations following neck dissection.

In this cross-sectional study, the sensibility, reliability, and validity of the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire were assessed in patients who underwent neck dissection for head and neck cancer. A sensibility questionnaire was used to assess face and content validity. Test-retest reliability was tested by re-mailing the questionnaire; validity, by evaluating differences in scores between patients undergoing different types of neck dissections and by correlating DASH scores with Neck Dissection Impairment Index (NDII) scores. The DASH was considered sensible by both patients and surgeons. The DASH was reliable with an intraclass coefficient of 0.91. The DASH showed differences between patients who underwent accessory nerve-sacrifice and nerve-sparing neck dissection. DASH scores strongly correlated with NDII scores. Thus, the DASH is a sensible, reliable, and valid instrument for assessing shoulder impairments and activity limitations following neck dissection.

Dynamic Adaptive Streaming over HTTP (DASH) is a convenient approach to transfer videos in an adaptive and dynamic way to the user. Therefore, this system makes best use of the bandwidth available. In this thesis, we investigate Dynamic Adaptive Streaming over HTTP (DASH) based on data collected from the lab experiments and user’s experiments. The objectives include investigation of how three different DASH players behave at different network conditions and up to which limit the players are tolerating the disturbances. We summarized the outcome of lab experiments on DASH at different adverse conditions and checked the lab results with user quality of experience at different adverse conditions to see up to which extent the users could tolerate the disturbances in different DASH players.

Streaming multimedia over the Internet is omnipresent but still in its infancy, specifically when it comes to theadaptation based on bandwidth/throughput measurements, clients competing for limited/shared bandwidth, and thepresence of a caching infrastructure. Nowadays the streaming infrastructure is existing over-the-top (OTT).Interestingly, these services are all delivered over-the-top of the existing networking infrastructure using the HypertextTransfer Protocol (HTTP) which resulted in the standardization of MPEG Dynamic Adaptive Streaming over HTTP(DASH).Video traffic is over 80% of the total internet traffic. Since Dynamic adaptive streaming over HTTP hasemerged it has a popular technique for video streaming on the internet. DASH allows the video player to adapt thebitrate according to the network conditions. DASH streaming client receives a manifest file, downloaded the referredvideo segments over HTTP, and play them back seamlessly emulated video streaming. This introduces latency of atleast one segment duration which decreases the quality of the user experience. In order to improve users over allQuality of Experience(QoE) a large number of adaptaion schemes were introduced to DASH.With such an importance of QoE on DASH, this thesis work investigates user acceptability of different DASHplayers. These players are exposed to different network conditions and the user analysis is given for each of thestreaming dash video for each player. The results of this thesis work include the analysis of the user rating for threedifferent players (Dash.js, GPAC and Shaka). The conclusion of this thesis is given by the quality of experience of thevideo streaming by the users which concludes that the Shaka player is preferred by the users compared to the othertwo players.

A life cycle of many known algae is influenced by the circadian clock. It seems probable that also Chromera velia, the closest known photosynthetic relative to Apicomplexa, uses circadian oscillator. We tested, if fluctuating of zoospore?s abundance is driven by the circadian clock. This rhythm is stable even in the constant light condition. Furthermore, three cryptochrome genes, involved in circadian rhythms, were sequenced and consequently phylogenetically investigated. Two of them were classified as CRY-DASH, the third is CRY-DASH-like. The rhythmicity of CRY-DASH expression in C. velia was also investigated. The level of expression was also tested under constant light and dark condition. It was suggested that expression of these genes is associated with the circadian oscillator. This is the first study of the circadian clock in C. velia.

The purpose of this thesis is to investigate and test the usage of HTTP/2 in dynamic adaptive video streaming as well as to take a look into how it can be used to benefit prefetching algorithms used with branched video. With a series of experiments the performance gains of using HTTP/2 rather than the older standard HTTP/1.1 has been investigated. The results has shown no significant change to player quality and buffer occupancy when using HTTP/2, though our tests has shown in a slight decrease in overall playback quality when using HTTP/2. When using a linear prefetch of two fragments an average quality improvement of 4.59% has been shown, however, the result is inconclusive due to variations in average quality between different values for how many fragments to prefetch. Average buffer occupancy has shown promise with a maximum increase of 12.58%, when using linear prefetch with three fragments. The values for buffer occupancy gains are conclusive. Two implementations for non-linear prefetching has been made. The first one uses HTTP/2 server push to deliver fragments for prefetching and the second one uses client-side invoked HTTP requests to pull fragments from the server. Using HTTP/2 server push has shown in a decrease of 2.5% in average total load time while using client-side pulling has shown in a decrease of 34% in average total load time.

Multi-video streaming allows the viewer to interact with the stream by choosing andswitching between several different camera angles to view the stream from. For this reportwe implement and evaluate adaptive multi-video streaming with dash.js. With the help ofdash.js and self-made additions, multiple parallel video streams which are synchronized intime are implemented to provide a good user experience with smooth switching betweenstreams. These streams will be delivered according to dash.js own HTTP-based AdaptiveStreaming algorithms to achieve adaptive streams for varying conditions. In order to optimizethe usage of the available bandwidth in terms of video quality in a multi-videoenvironment we implement probabilities of camera switching to adapt qualities and allocatedbandwidth of streams. By utilizing the functions of dash.js we create two prefetchingpolicies and analyze these results together with the standard non-prefetch dash.js implementationin a multi-view video environment. Our results present the improvements interms of stalling with a prefetch implementation and the possibility of a good policy tofurther optimize a multi-view video implementation in terms of stalling, quality and bandwidthusage. Evaluation of dash.js compatibility for a multi-view video environment is alsodiscussed where pros and cons of dash.js in their current state are presented.

Over the past 10 years online video streaming has seen a tremendous increase in popularity, as it has become a great source of both entertainment and education. This increase in popularity has led to demands for higher quality streams, shorter buffering time and service adaptivity, based on the user’s personal prerequisites. These demands together with a constant increase in Internet usage have posed several challenges for streaming service providers to overcome. Within this master thesis an exploratory research and development project has been conducted. The project’s purpose has been to investigate common approaches, standards and trends related to establishing a multimedia streaming service. Based on the results from these investigations, the purpose has furthermore been to design and implement a proof-of-concept streaming server fulfilling the thesis internship company’s needs and requirements. Research has concluded that there are at least five vital components, which have to be carefully considered in order to establish a successful streaming service. These vital components are; the service system structure, the service application programming interface (API), the service hosting solution, the service data storage solution and finally the actual streaming module. Based on results from conducted investigations of common design approaches for each vital component, decisions for the thesis project implementation have been made. The resulting system has been built using the event-based system structure framework Node.js. A representational state transfer (REST) API has furthermore been implemented for managing client request routing. The resulting system has been implemented on a self-hosted server solution even though this is neither a preferred choice in theory nor common practice. The decision has however been made due to future plans at the thesis internship company of investing in a corporate-wide cloud-based server solution. For the service data storage solution the relation-based database management system MySQL has been implemented. For the final recognized vital component, the streaming module, support for HTTP-based multimedia streams has been implemented. This choice of technique has been made due to the many benefits brought on by using HTTP, such as cost efficiency and bandwidth optimization. The use of HTTP is also currently a trending choice of technique Thesis for Master’s Degree at HIT and LiU within the streaming community due to the recently published standard MPEG-DASH.

HTTP Adaptive Streaming (HAS) has now become ubiquitous, and it accounts for a large proportion of multimedia delivery over the Internet. Consequently, it poses new challenges for content providers and network operators. In this study, we aim to improve the user’s Quality of Experience (QoE) for HAS using from two main approaches including client centric approach and network assisted approach. In the client centric approach, we address the issue of enhancing the client’s QoE by proposing a fuzzy logic–based video bitrate adaptation and prediction mechanism for Dynamic Adaptive Streaming over HTTP (DASH) players. This adaptation mechanism allows HAS players to take appropriate actions sooner than existing methods to prevent playback interruptions caused by buffer underrun and reduce the ON-OFF traffic phenomena, which causes instability and unfairness among competing players. Our results show that compared to other studied methods, our proposed method has two advantages: better fairness among multiple competing players by almost 50% on average and as much as 80% as indicated by Jain’s fairness index, and better perceived quality of video by almost 8% on average and as much as 17%, according to the eMOS model. In the network assisted approach, we propose a novel mechanism for HAS stream adaptation in the context of wireless mobile networks. The proposed mechanism leverages recent advances in the 3GPP DASH specification, including the optional feature of QoE measurement and reporting for DASH clients. As part of the proposed mechanism, we formulate a utility-maximization problem that incorporates factors influencing QoE to specify the optimum value of Quality of Service (QoS)-related parameters for HAS streams within a wireless mobile network. The results of our simulations demonstrate that our proposed system results in better perceived quality of video, measured by Mean Opinion Score (MOS), by almost 7% on average, while lowering the freezing period by almost 20% on average across HAS users when compared to other approaches where HAS users only rely on local adaptation logics.