Distributed Linear Precoding and User Selection in Coordinated Multicell Systems

In this manuscript we tackle the problem of semi-distributed user selection with distributed linear precoding for sum rate maximization in multiuser multicell systems. A set of adjacent base stations (BS) form a cluster in order to perform coordinated transmission to cell-edge users, and coordination is carried out through a central processing unit (CU). However, the message exchange between BSs and the CU is limited to scheduling control signaling and no user data or channel state information (CSI) exchange is allowed. In the considered multicell coordinated approach, each BS has its own set of cell-edge users and transmits only to one intended user while interference to non-intended users at other BSs is suppressed by signal steering (precoding). We use two distributed linear precoding schemes, Distributed Zero Forcing (DZF) and Distributed Virtual Signal-to-Interference-plus-Noise Ratio (DVSINR). Considering multiple users per cell and the backhaul limitations, the BSs rely on local CSI to solve the user selection problem. First we investigate how the signal-to-noise-ratio (SNR) regime and the number of antennas at the BSs affect the effective channel gain (the magnitude of the channels after precoding) and its relationship with multiuser diversity. Considering that user selection must be based on the type of implemented precoding, we develop metrics of compatibility (estimations of the effective channel gains) that can be computed from local CSI at each BS and reported to the CU for scheduling decisions. Based on such metrics, we design user selection algorithms that can find a set of users that potentially maximizes the sum rate. Numerical results show the effectiveness of the proposed metrics and algorithms for different configurations of users and antennas at the base stations.Comment: 12 pages, 6 figure

JamLab: Augmenting Sensornet Testbeds with Realistic and Controlled Interference Generation

Radio interference drastically affects the performance of sensor-net communications, leading to packet loss and reduced energy-efficiency. As an increasing number of wireless devices operates on the same ISM frequencies, there is a strong need for understanding and debugging the performance of existing sensornet protocols under interference. Doing so requires a low-cost flexible testbed infrastructure that allows the repeatable generation of a wide range of interference patterns. Unfortunately, to date, existing sensornet testbeds lack such capabilities, and do not permit to study easily the coexistence problems between devices sharing the same frequencies. This paper addresses the current lack of such an infrastructure by using off-the-shelf sensor motes to record and playback interference patterns as well as to generate customizable and repeat-able interference in real-time. We propose and develop JamLab: a low-cost infrastructure to augment existing sensornet testbeds with accurate interference generation while limiting the overhead to a simple upload of the appropriate software. We explain how we tackle the hardware limitations and get an accurate measurement and regeneration of interference, and we experimentally evaluate the accuracy of JamLab with respect to time, space, and intensity. We further use JamLab to characterize the impact of interference on sensornet MAC protocols

Comparing the content of instruments assessing environmental factors using the International Classification of Functioning, Disability and Health

Purpose: To describe and compare the content of instruments that assess environmental factors using the International Classification of Functioning, Disability and Health (ICF). Methods: A systematic search of PubMed, CINAHL and PEDro databases was conducted using a pre-determined search strategy. The identified instruments were screened independently by two investigators, and meaningful concepts were linked to the most precise ICF category according to published linking rules. Results: Six instruments were included, containing 526 meaningful concepts. Instruments had between 20% and 98% of items linked to categories in Chapter 1. The highest percentage of items from one instrument linked to categories in Chapters 2–5 varied between 9% and 50%. The presence or absence of environmental factors in a specific context is assessed in 3 instruments, while the other 3 assess the intensity of the impact of environmental factors. Discussion: Instruments differ in their content, type of assessment, and have several items linked to the same ICF category. Most instruments primarily assess products and technology (Chapter 1), highlighting the need to deepen the discussion on the theory that supports the measurement of environmental factors. This discussion should be thorough and lead to the development of methodologies and new tools that capture the underlying concepts of the ICF

Service evaluation of the GOALS family-based childhood obesity treatment intervention during the first 3 years of implementation.

Objectives: To evaluate the impact of the GOALS (Getting Our Active Lifestyles Started) family-based childhood obesity treatment intervention during the first 3 years of implementation. Design: Single-group repeated measures with qualitative questionnaires. Setting: Community venues in a socioeconomically deprived, urban location in the North-West of England. Participants: 70 overweight or obese children (mean age 10.5 years, 46% boys) and their parents/carers who completed GOALS between September 2006 and March 2009. Interventions: GOALS was a childhood obesity treatment intervention that drew on social cognitive theory to promote whole family lifestyle change. Sessions covered physical activity (PA), diet and behaviour change over 18 2 h weekly group sessions (lasting approximately 6 months). A Template for Intervention Description and Replication (TIDieR) checklist of intervention components is provided. Primary and secondary outcome measures: The primary outcome measure was child body mass index (BMI) z-score, collected at baseline, post-intervention and 12 months. Secondary outcome measures were child selfperceptions, parent/carer BMI and qualitative changes in family diet and PA (parent/carer questionnaire). Results: Child BMI z-score reduced by 0.07 from baseline to post-intervention (p<0.001) and was maintained at 12 months (p<0.05). There was no change in parent/carer BMI or child self-perceptions, other than an increase in perceived social acceptance from baseline to post-intervention (p<0.05). Parents/carers reported positive changes to family PA and dietary behaviours after completing GOALS. Conclusions: GOALS completion was associated with small improvements in child BMI z-score and improved family PA and dietary behaviours. Several intervention modifications were necessary during the implementation period and it is suggested childhood obesity treatment interventions need time to embed before a definitive evaluation is conducted. Researchers are urged to use the TIDieR checklist to ensure transparent reporting of interventions and facilitate the translation of evidence to practice

Perceptions, Beliefs, and Attitudes of First Year Third-Level Students: An Empirical Study of Portuguese, Russian, Polish, Finnish, and Irish Students

The contemporary skillset of undergraduates includes a degree of sophistication in the application of ICT within their daily lives as well as within the higher education environment. The assumption of the student as a digital native, with the ability to cognitively process information in an ICT focused educational environment, is omnipresent in higher education. It has been suggested this assumption does not aid learning and adds an additional burden on the student. This study investigated whether experiences and perceptions, of mathematics and online assessment, are common to students studying in different countries and their respective higher education systems. The purpose of the investigation was to determine what issues influence the attitudes of students in the application of ICT for the online assessment of mathematics in the first year of undergraduate programmes. The investigation was conducted online by means of a quantitative questionnaire, consisting of 16 survey items, using Google Forms to self-selecting students (n=374) across several academic disciplines including engineering, business studies, media, and tourism. The survey was delivered in English to the majority students and translated to Russian for the Russian students to enable each group to reply in their own native language. The questionnaire design utilized a 6-point Likert scale where students were asked to express their experiences and perceptions of mathematics and online assessment in their chosen programme of study. The data was exported to IBM SPSSv24 and regression analyses were conducted to ascertain possible associations and relationships between the two student groups in the case study. The results of the investigation reveal some peculiar features and the respective investigation outcomes of the investigation will be utilized in the design of learner-centered assessments and shared with international partners

A new fractional derivative without singular kernel: Application to the modelling of the steady heat flow

In this article we propose a new fractional derivative without singular kernel. We consider the potential application for modeling the steady heat-conduction problem. The analytical solution of the fractional-order heat flow is also obtained by means of the Laplace transform.Comment: 1 figur

Effects of dual-task interventions on gait performance of patients with parkinson’s disease: a systematic review

OBJECTIVE: Parkinson’s disease is characterized by motor and non-motor symptoms that impair patients’ gait performance, especially while performing dual/concurrent tasks. These deficits impair patients’ daily function, because dual-tasking is a crucial ability in terms of everyday living. The aim of this study was to systematically review the effects of dual task interventions on gait performance of patients with Parkinson’s disease. METHOD: Studies were retrieved from MEDLINE/PubMed, LILACS and SciELO. We used the PICOS strategy to determine eligibility criteria. The search strategy included an advanced search on the included databases, using the following search query: “Parkinson’s Disease” AND “Double Task” OR “Concurrent Tasks” OR “Gait” AND “Walk”. Study selection was carried out by two independent researchers and a third one was called when consensus was needed. RESULTS: A total of 188 articles were identified: 169 articles from Medline/PubMed, 10 articles in SciELO, 8 articles in LILACS and 1 item from manual searches. A total of 56 articles were analyzed regarding the eligibility and exclusion criteria based on full text. A final total of 7 studies were included in the systematic review. CONCLUSION: The different types of dual-task interventions reported (dance, sound stimuli, visual and somatosensory) were associated to improvements in several gait performance indicators of Parkinson’s disease patients, including gait speed, stride time and length, cadence and step length. External stimuli seem to play a critical role on specific training effects on dual-task gait performance.info:eu-repo/semantics/publishedVersio

Sleep Disorders and Genes

Versão preprintThe sleep-wake cycle is a neurobiological phenomenon that shows intervals of activity alternating with restfulness that appears with a periodicity approximating the 24h day-night cycle. The sleep-wake cycle is under the control of diverse neuroanatomical and neurochemical systems, including monoaminergic, cholinergic, adenosinergic among many other systems. In addition, neuroanatomical centers linked to sleep promotion, such as hypothalamus, project to the cerebral cortex, subcortical relays and brainstem. In addition, the sleep-wake cycle has been associated to aberrant features known as sleep disorders. Here, we will discuss the role of specific gene expression on sleep disturbances. Given the expansion of the knowledge in the sleep-wake cycle area, it is indeed ambitious to describe all the genetics involved in the sleep modulation. However, in this chapter we reviewed the current understanding of the sleep disorders and gene expression.info:eu-repo/semantics/publishedVersio

Network Diversity Multiple Access in Rayleigh Fading Correlated Channels with Imperfect Channel and Collision Multiplicity Estimation

Network diversity multiple access or NDMA is the family of algorithms with the highest potential throughput in the literature of signal-processing-assisted random access. NDMA uses the concept of protocol-induced retransmissions to create an adaptive source of physical (PHY) layer diversity. This adaptive diversity is used to resolve packet collisions (via signal separation) without the explicit need (or as a complement) of a multiple antenna receiver. This paper proposes a further improvement on the modelling of NDMA by considering the effects of imperfect channel and collision multiplicity estimation. In addition, this work considers channel correlation between consecutive retransmissions (i.e., temporal correlation). Conventionally, the analysis of NDMA assumes that any error in the collision multiplicity estimation translates into the loss of all contending packets. This is an optimistic assumption because even when the multiplicity has been correctly estimated, errors can still occur. On the other hand, it is also pessimistic because correct reception can also occur when the multiplicity has been incorrectly estimated. This paper presents a more detailed study of the performance of the protocol considering these more specific reception cases

Uma abordagem à avaliação de ambientes virtuais de aprendizagem

A avaliação de ambientes de aprendizagem é um tema complexo e multifatorial. No presente trabalho apresenta-se a proposta de avaliação de um ambiente virtual de aprendizagem utilizado para o ensino da farmacoterapia baseado em casos clínicos. Utilizou-se a versão portuguesa reduzida do WEBLEI assim como a Evaluative Assertion Analysis para a recolha de dados. Os resultados obtidos são abonatórios ao nível do acesso aos materiais, interação com os conteúdos e a plataforma, interação com o docente assim como na estruturação e design. Foram reveladas algumas fragilidades nomeadamente ao nível da interação entre estudantes e gestão de tempo. As inferências obtidas serão alvo de reflexão pela equipa de desenvolvimento da UC no processo contínuo de melhoria da iniciativa.The assessment of learning environments is a complex and multifatorial topic. In this paper we present a proposal for evaluating a virtual learning environment used for the teaching of pharmacotherapy based on clinical cases. We used the Portuguese reduced version of WEBLEI and Evaluative Assertion Analysis for data collection. The results are satisfatory in terms of access to materials, interaction with content and platform, interaction with the teacher as well as structuring and design.La evaluación de los ambientes de aprendizaje es un tema complejo y multifatorial. En este trabajo se presenta la propuesta de evaluación de un ambiente de aprendizaje virtual utilizado para enseñar la farmacoterapia basada en casos clínicos. Se utilizó la versión en Portugues de WEBLEI y el Evaluative Assertion Analysis para la recolección datos. Los resultados son satisfatorios en términos de acceso a los materiales, la interacción con el contenido y la plataforma, interacción con el profesor, así como la estructuración y diseño. Algunas debilidades fueron reveladas en particular, el nivel de interacción entre los estudiantes y el manejo del tiempo. Las inferencias obtenidas serán objeto de examen por el equipo de desarrollo para lo mejoramiento continuo de la iniciativa.Apoio e Financiamento: Este trabalho é financiado por Fundos Nacionais através da FCT – Fundação para a Ciência e a Tecnologia no âmbito do projeto PEst-OE/CED/UI1661/2011 do CIE