Improving sensor network performance with wireless energy transfer

Through recent technology advances in the field of wireless energy transmission Wireless Rechargeable Sensor Networks have emerged. In this new paradigm for wireless sensor networks a mobile entity called mobile charger (MC) traverses the network and replenishes the dissipated energy of sensors. In this work we first provide a formal definition of the charging dispatch decision problem and prove its computational hardness. We then investigate how to optimise the trade-offs of several critical aspects of the charging process such as: a) the trajectory of the charger; b) the different charging policies; c) the impact of the ratio of the energy the Mobile Charger may deliver to the sensors over the total available energy in the network. In the light of these optimisations, we then study the impact of the charging process to the network lifetime for three characteristic underlying routing protocols; a Greedy protocol, a clustering protocol and an energy balancing protocol. Finally, we propose a mobile charging protocol that locally adapts the circular trajectory of the MC to the energy dissipation rate of each sub-region of the network. We compare this protocol against several MC trajectories for all three routing families by a detailed experimental evaluation. The derived findings demonstrate significant performance gains, both with respect to the no charger case as well as the different charging alternatives; in particular, the performance improvements include the network lifetime, as well as connectivity, coverage and energy balance properties

Stably computing order statistics with arithmetic population protocols.

In this paper we initiate the study of populations of agents with very limited capabilities that are globally able to compute order statistics of their arithmetic input values via pair-wise meetings. To this extent, we introduce the Arithmetic Population Protocol (APP) model, embarking from the well known Population Protocol (PP) model and inspired by two recent papers in which states are treated as integer numbers. In the APP model, every agent has a state from a set Q of states, as well as a fixed number of registers (independent of the size of the population), each of which can store an element from a totally ordered set S of samples. Whenever two agents interact with each other, they update their states and the values stored in their registers according to a joint transition function. This transition function is also restricted; it only allows (a) comparisons and (b) copy / paste operations for the sample values that are stored in the registers of the two interacting agents. Agents can only meet in pairs via a fair scheduler and are required to eventually converge to the same output value of the function that the protocol globally and stably computes. We present two different APPs for stably computing the median of the input values, initially stored on the agents of the population. Our first APP, in which every agent has 3 registers and no states, stably computes (with probability 1) the median under any fair scheduler in any strongly connected directed (or connected undirected) interaction graph. Under the probabilistic scheduler, we show that our protocol stably computes the median in O(n^6) number of interactions in a connected undirected interaction graph of $n$ agents. Our second APP, in which every agent has 2 registers and O(n^2 log{n}) states, computes to the correct median of the input with high probability in O(n^3 log{n}) interactions, assuming the probabilistic scheduler and the complete interaction graph. Finally we present a third APP which, for any k, stably computes the k-th smallest element of the input of the population under any fair scheduler and in any strongly connected directed (or connected undirected) interaction graph. In this APP every agent has 2 registers and n states. Upon convergence every agent has a different state; all these states provide a total ordering of the agents with respect to their input values

Micro wholesaling businesses involved in the sector of confectionary products - strategies of survival and growth

It can be argued that the problematic situation where micro Greek wholesaling businesses find themselves has been a result of the strong presence of supermarkets and superstores in the last years. The researcher attempts to picture the current market reality that constitutes the background of the Thesis by posing the main research question: "How can micro Greek wholesaling businesses involved in the confectionary products' sector identify and implement suitable survival and growth strategies in order to cope with increasing competition in a market characterized by a large expansion of supermarkets and chain stores?". The factors that triggered research are related to the researcher's avocation with the sector of confectionary products; having worked in a micro family wholesaling enterprise in the past (and still involved in it occasionally when demand for confectionary products is increased), the survival and growth prospects of this firm constitutes an issue of high importance for the researcher and his family. The researcher believes that the study of similar wholesaling firms-case studies would highlight potential survival and growth strategies, useful for the family business; in this way, he holds the view that he contributes to the solution of an intense family problem. Apart from the personal interest for the survival and growth of micro wholesaling firms, it can be argued that the confectionary products' sector is a dynamic field that provides the opportunities to a researcher to evolve to a consultant or a specialist practitioner

Do antidepressants cure or create abnormal brain states?

Moncrieff and Cohen argue that psychotropic drugs create abnormal states that may co-incidentally relieve symptoms of mental illness

Enhancing social impacts of third sector organizations amid the Covid-19 pandemic

The effectiveness achieved by Third Sector Organizations (TSOs) is directly linked to goals based on their missions and results generated by their actions, which can positively or negatively impact their beneficiaries. Even in normal situations, there is already a difficulty in gathering resources to maintain their operations. The advent of the Covid-19 pandemic tends to worsen this situation depending on their social innovation and resilience capacities. From such an issue, the present study identifies strategies and lessons learned by Portuguese and Brazilian TSOs that were affected by the Covid-19 pandemic. Moreover, an assessment is made on what they did to maximize the positive social impacts and minimize the negative ones, considering the crisis management theory. Then, a qualitative phenomenological-type exploratory research was conducted, whose data was collected primarily from in-depth interviews and secondarily from documents published in the TSOs’ websites. The data collected from thirty-two Portuguese and Brazilian TSOs were assessed by means of content analysis, based on existing theory and on new subjects arisen from the reported experiences. The results have shown that, regardless the institutional model, most of them were not prepared to deal with that crisis. Besides, they had been reacting as the effects were underway, seeking to maximize the positive social impacts and to minimize the negative ones. Additionally, it is highlighted the importance of a flexible management to adapting to a new challenge in order to achieve different priority goals and to meet the main beneficiaries’ needs during the pandemic. Although in an early-stage research, interesting results have already been found, which can lead to contributions to management, governance, leadership, strategy, social innovation, sustainability and, ultimately, to the design of a crisis management model for TSOs. This research also calls for complementary future works.info:eu-repo/semantics/acceptedVersio

COPD care delivery pathways in five European Union countries : mapping and health care professionals' perceptions

Background: COPD is among the leading causes of chronic morbidity and mortality in the European Union with an estimated annual economic burden of €25.1 billion. Various care pathways for COPD exist across Europe leading to different responses to similar problems. Determining these differences and the similarities may improve health and the functioning of health services. Objective: The aim of this study was to compare COPD patients’ care pathway in five European Union countries including England, Ireland, the Netherlands, Greece, and Germany and to explore health care professionals’ (HCPs) perceptions about the current pathways. Methods: HCPs were interviewed in two stages using a qualitative, semistructured email interview and a face-to-face semistructured interview. Results: Lack of communication among different health care providers managing COPD and comorbidities was a common feature of the studied care pathways. General practitioners/family doctors are responsible for liaising between different teams/services, except in Greece where this is done through pulmonologists. Ireland and the UK are the only countries with services for patients at home to shorten unnecessary hospital stay. HCPs emphasized lack of communication, limited resources, and poor patient engagement as issues in the current pathways. Furthermore, no specified role exists for pharmacists and informal carers. Conclusion: Service and professional integration between care settings using a unified system targeting COPD and comorbidities is a priority. Better communication between health care providers, establishing a clear role for informal carers, and enhancing patients’ engagement could optimize current care pathways resulting in a better integrated system

Crisis management model for third sector organizations amid the COVID-19 pandemic

The pandemic caused by COVID-19 impacted people and organizations, including the Third Sector, which has seen greater demand to minimize the social and economic effects generated by the crisis. Based on this issue, the present study aimed to give visibility to the effects and impacts caused by the pandemic, the main actions and strategies adopted by Third Sector organizations and, based on these findings, to propose a crisis management model for the Third Sector. By virtue, qualitative exploratory research of the phenomenological type was carried out, whose data were collected from in-depth interviews and information disclosed on the institutions' websites. Thus, the experiences reported by 32 Brazilian and Portuguese organizations underwent an abductive content analysis, considering the existing theoretical framework and the contents of the interviews. The results showed that none of the organizations was fully prepared to deal with the crisis effects and reacted as situations and events occurred. And, unlike what was reported in previous studies, none of these organizations shut down permanently, financial resources kept on existing, and not all the effects generated by the pandemic meant negative impacts, but opportunities for improvement, as well as breaks in paradigms and learning. The results also showed that adopting good governance levels and agile and flexible management models boosted the organizations’ resilience. Therefore, it was possible to propose a crisis management model to be applied to the Third Sector and to suggest future works and practical and academic applications.A pandemia causada pela COVID-19 impactou pessoas e organizações, inclusive do Terceiro Setor, que se viram com maior procura para minimizar os efeitos sociais e económicos gerados pela crise. Com base nesta questão, o presente estudo teve como objetivo dar visibilidade aos efeitos e impactos gerados pela pandemia, às principais ações e estratégias adotadas pelas organizações do Terceiro Setor e, a partir destes achados, propor um modelo de gestão de crise para o Terceiro Setor. Para isso, foi realizada uma investigação exploratória qualitativa do tipo fenomenológica, cujos dados foram recolhidos a partir de entrevistas em profundidade e de informações divulgadas nos sítios web das instituições. Assim, as experiências relatadas por 32 organizações brasileiras e portuguesas passaram por uma análise de conteúdo abdutiva, considerando o quadro teórico existente e o conteúdo das entrevistas. Os resultados mostraram que nenhuma das organizações estava totalmente preparada para lidar com os efeitos da crise, e reagiu à medida que situações e eventos iam surgindo. E, ao contrário do que foi relatado em estudos anteriores, nenhuma dessas organizações encerrou suas atividades permanentemente, houve disponibilidade financeira, e nem todos os efeitos gerados pela pandemia significaram impactos negativos, mas, sobretudo, oportunidades de melhorias, quebras de paradigmas e aprendizados. Os resultados evidenciaram ainda que a adoção de bons níveis de governança e de modelos de gestão ágeis e flexíveis reforçaram a resiliência das organizações. Por conseguinte, foi possível propor um modelo de gestão de crise para o Terceiro Setor e sugerir futuros trabalhos e aplicações práticas e académicas

Maximum Cliques in Graphs with Small Intersection Number and Random Intersection Graphs

In this paper, we relate the problem of finding a maximum clique to the intersection number of the input graph (i.e. the minimum number of cliques needed to edge cover the graph). In particular, we consider the maximum clique problem for graphs with small intersection number and random intersection graphs (a model in which each one of $m$ labels is chosen independently with probability $p$ by each one of $n$ vertices, and there are edges between any vertices with overlaps in the labels chosen). We first present a simple algorithm which, on input $G$ finds a maximum clique in $O(2^{2^m + O(m)} + n^2 \min\{2^m, n\})$ time steps, where $m$ is an upper bound on the intersection number and $n$ is the number of vertices. Consequently, when $m \leq \ln{\ln{n}}$ the running time of this algorithm is polynomial. We then consider random instances of the random intersection graphs model as input graphs. As our main contribution, we prove that, when the number of labels is not too large ($m=n^{\alpha}, 0< \alpha <1$), we can use the label choices of the vertices to find a maximum clique in polynomial time whp. The proof of correctness for this algorithm relies on our Single Label Clique Theorem, which roughly states that whp a "large enough" clique cannot be formed by more than one label. This theorem generalizes and strengthens other related results in the state of the art, but also broadens the range of values considered. As an important consequence of our Single Label Clique Theorem, we prove that the problem of inferring the complete information of label choices for each vertex from the resulting random intersection graph (i.e. the \emph{label representation of the graph}) is \emph{solvable} whp. Finding efficient algorithms for constructing such a label representation is left as an interesting open problem for future research