Lower bounds on systolic gossip

AbstractGossiping is an extensively investigated information dissemination process in which each processor has a distinct item of information and has to collect all the items possessed by the other processors. In this paper we provide an innovative and general lower bound technique relying on the novel notion of delay digraph of a gossiping protocol and on the use of matrix norm methods. Such a technique is very powerful and allows the determination of new and significantly improved lower bounds in many cases. In fact, we derive the first general lower bound on the gossiping time of systolic protocols, i.e., constituted by a periodic repetition of simple communication steps. In particular, given any network of n processors and any systolic period s, in the directed and the undirected half-duplex cases every s-systolic gossip protocol takes at least log(n)/log(1/λ)−O(loglog(n)) time steps, where λ is the unique solution between 0 and 1 of λ·p⌊s/2⌋(λ)·p⌈s/2⌉(λ)=1, with pi(λ)=1+λ2+⋯+λ2i−2 for any integer i>0. We then provide improved lower bounds in the directed and half-duplex cases for many well-known network topologies, such as Butterfly, de Bruijn, and Kautz graphs. All the results are extended also to the full-duplex case. Our technique is very general, as for s→∞ it allows the determination of improved results even for non-systolic protocols. In fact, for general networks, as a simple corollary it yields a lower bound only an O(loglog(n)) additive factor far from the general one independently proved in [Proc. 1st ACM Symposium on Parallel Algorithms and Architectures (SPAA), 1989, p. 318; Topics in Combinatorics and Graph Theory (1990) 451; SIAM Journal on Computing 21(1) (1992) 111; Discrete Applied Mathematics 42 (1993) 75] for all graphs and any (non-systolic) gossip protocol. Moreover, for specific networks, it significantly improves with respect to the previously known results, even in the full-duplex case. Correspondingly, better lower bounds on the gossiping time of non-systolic protocols are determined in the directed, half-duplex and full-duplex cases for Butterfly, de Bruijn, and Kautz graphs. Even if in this paper we give only a limited number of examples, our technique has wide applicability and gives a general framework that often allows to get improved lower bounds on the gossiping time of systolic and non-systolic protocols in the directed, half-duplex and full-duplex cases

Engineering Resilient Collective Adaptive Systems by Self-Stabilisation

Collective adaptive systems are an emerging class of networked computational systems, particularly suited in application domains such as smart cities, complex sensor networks, and the Internet of Things. These systems tend to feature large scale, heterogeneity of communication model (including opportunistic peer-to-peer wireless interaction), and require inherent self-adaptiveness properties to address unforeseen changes in operating conditions. In this context, it is extremely difficult (if not seemingly intractable) to engineer reusable pieces of distributed behaviour so as to make them provably correct and smoothly composable. Building on the field calculus, a computational model (and associated toolchain) capturing the notion of aggregate network-level computation, we address this problem with an engineering methodology coupling formal theory and computer simulation. On the one hand, functional properties are addressed by identifying the largest-to-date field calculus fragment generating self-stabilising behaviour, guaranteed to eventually attain a correct and stable final state despite any transient perturbation in state or topology, and including highly reusable building blocks for information spreading, aggregation, and time evolution. On the other hand, dynamical properties are addressed by simulation, empirically evaluating the different performances that can be obtained by switching between implementations of building blocks with provably equivalent functional properties. Overall, our methodology sheds light on how to identify core building blocks of collective behaviour, and how to select implementations that improve system performance while leaving overall system function and resiliency properties unchanged.Comment: To appear on ACM Transactions on Modeling and Computer Simulatio

Absorption and Enjoyment During Listening to Acoustically Masked Stories

© The Author(s) 2020. Comprehension of speech masked by background sound requires increased cognitive processing, which makes listening effortful. Research in hearing has focused on such challenging listening experiences, in part because they are thought to contribute to social withdrawal in people with hearing impairment. Research has focused less on positive listening experiences, such as enjoyment, despite their potential importance in motivating effortful listening. Moreover, the artificial speech materials—such as disconnected, brief sentences—commonly used to investigate speech intelligibility and listening effort may be ill-suited to capture positive experiences when listening is challenging. Here, we investigate how listening to naturalistic spoken stories under acoustic challenges influences the quality of listening experiences. We assess absorption (the feeling of being immersed/engaged in a story), enjoyment, and listening effort and show that (a) story absorption and enjoyment are only minimally affected by moderate speech masking although listening effort increases, (b) thematic knowledge increases absorption and enjoyment and reduces listening effort when listening to a story presented in multitalker babble, and (c) absorption and enjoyment increase and effort decreases over time as individuals listen to several stories successively in multitalker babble. Our research indicates that naturalistic, spoken stories can reveal several concurrent listening experiences and that expertise in a topic can increase engagement and reduce effort. Our work also demonstrates that, although listening effort may increase with speech masking, listeners may still find the experience both absorbing and enjoyable

Body composition measurement in African and Caribbean children and its relationship with morbidity

The global increase in obesity prevalence has led to a surge in metabolic disease in both adults and children. Furthermore, the burden of obesity and its related morbidities is not equally distributed across the UK population, with those from minority ethnic groups particularly affected. Effective paediatric epidemiological monitoring and clinical referral requires improved tools for assessing body fatness, and other body composition measures related to metabolic disease are needed. Presently the body mass index (BMI) used to identify overweight and obesity suffers from poor sensitivity and specificity, leading to misclassification of children, especially those from minority ethnic groups. Additionally BMI gives no indication of body fat distribution. Assessment tools specifically for African and Caribbean childhood populations are lacking and the aim of this thesis was to develop a range of assessment tools specifically for this population group. This thesis comprised four studies. In the first study the equations in the Tanita BC-418 bioimpedance (BIA) system used to predict fat mass (FM) and appendicular skeletal muscle mass (SMMa) were re-validated using dual-energy x-ray absorptiometry (DXA) as the criterion method in a sample of 44 African and Caribbean children aged 5-18 years. FM (kg) and SMMa (kg) were quantified by DXA and linear regression analysis used to produce new equations based on height2 /impedance. The key findings from this study were that BIA generally under-estimated FM and over-estimated SMMa in this population group, irrespective of age and gender. In the second study, the corrected measures of FM and SMMa were applied to an existing dataset of 1,336 African/Caribbean children aged between 5-16y whose body composition had been measured using the Tanita BC418 system. Percentile charts for %FM, %FFM, SMMa (kg), %SMMa and SMMa/FMM x 100 were generated using the software LMS Chartmaker. In the third study, blood pressure percentile charts and tables were developed based on data (n, 900) extracted for African and Caribbean children aged 5-18 years from the Health Survey for England data archives, 1991-2008. The centile curves for the anthropometric measures revealed gender and age-related patterns which compared closely to equivalent charts for Caucasian children. Finally in the fourth study, percentile charts and tables for waist circumference (cm) were developed using the same sample population. The findings from these studies provide the tools and preliminary evidence to support the use of African-Caribbean specific references for body composition and blood pressure measures in children and youths in the UK. The overall conclusion from this thesis indicates that paediatric overweight and obesity varies across different ethnic groups and this variation needs to be considered in the context of obesity surveillance and clinical assessment which themselves are determined by national obesity policy formulation and implementation. These are the first body composition percentile charts for African and Caribbean children living in the UK. These charts should replace BMI charts used for obesity assessment in paediatric and epidemiological settings as they are better tools for assessing overweight, obesity and sarcopenia

From distributed coordination to field calculus and aggregate computing

open6siThis work has been partially supported by: EU Horizon 2020 project HyVar (www.hyvar-project .eu), GA No. 644298; ICT COST Action IC1402 ARVI (www.cost -arvi .eu); Ateneo/CSP D16D15000360005 project RunVar (runvar-project.di.unito.it).Aggregate computing is an emerging approach to the engineering of complex coordination for distributed systems, based on viewing system interactions in terms of information propagating through collectives of devices, rather than in terms of individual devices and their interaction with their peers and environment. The foundation of this approach is the distillation of a number of prior approaches, both formal and pragmatic, proposed under the umbrella of field-based coordination, and culminating into the field calculus, a universal functional programming model for the specification and composition of collective behaviours with equivalent local and aggregate semantics. This foundation has been elaborated into a layered approach to engineering coordination of complex distributed systems, building up to pragmatic applications through intermediate layers encompassing reusable libraries of program components. Furthermore, some of these components are formally shown to satisfy formal properties like self-stabilisation, which transfer to whole application services by functional composition. In this survey, we trace the development and antecedents of field calculus, review the field calculus itself and the current state of aggregate computing theory and practice, and discuss a roadmap of current research directions with implications for the development of a broad range of distributed systems.embargoed_20210910Viroli, Mirko; Beal, Jacob; Damiani, Ferruccio; Audrito, Giorgio; Casadei, Roberto; Pianini, DaniloViroli, Mirko; Beal, Jacob; Damiani, Ferruccio; Audrito, Giorgio; Casadei, Roberto; Pianini, Danil

Midwifery practice in a rural area, with an account of a series of cases

#1. To a very great extent, the sound health of the population at large is dependent on the sound health of the individual. #2. In the first place, the sound health of the individual is dependent on a "good start in life." #3. "A good start in life" is dependent on the sound health of the child- bearing woman. #4. To a very great extent the sound health of the childbearing woman is dependent on sound midwifery, ante-natal, intra-natal and post-natal. #5. Sound midwifery, ante-natal, intra-natal and post-natal can only be obtained by proper co-operation between all those concerned, viz, the public health authority: the general public: the child -bearing woman: the medical practitioner and the maternity nurse. #6. The Public Health authority can assist by a general improvement in housing conditions, by the provision of labour units as described, by the provision of a resident maternity nurse for each case and by the . provision of sterilised maternity outfits for each case. #7. The general public can assist by a realisation that maternity work is of prime importance and should be primarily in the hands of the medical profession. # 8. The child-bearing woman can assist very greatly by the early notification of pregnancy to her family doctor. #9. The family doctor, who should have a thorough knowledge of the obstetric art, should have continuous personal charge of the child-bearing woman during her ante-natal, intra-natal and post-natal periods. In every case he should have the assistance of a well-trained resident maternity nurse

UWOMJ Volume 47, Number 4, November 1977

Schulich School of Medicine & Dentistryhttps://ir.lib.uwo.ca/uwomj/1220/thumbnail.jp

Clergy stress, complex trauma and Sabbath practice : a study on Sabbath practice as healing process for clergy serving in stressful appointments

https://place.asburyseminary.edu/ecommonsatsdissertations/1849/thumbnail.jp

The Role of Place in Malcolm Cowley\u27s Blue Juniata and Exile\u27s Return

This study examines the various ways in which Malcolm Cowley develops and uses sense of place in his works Blue Juniata: Collected Poems and Exile\u27s Return. Through examination of the literature, I identify four phases of place sense. Starting with childhood in the Identification phase, I illustrate the development of Cowley\u27s place perspective through his poems and writings. As he moves through Adventure and Exile phases, I discuss their relation to the Identification phase and to each other. Likewise, I consider the role of the Nostalgia phase as a bridge from literary to experiential perception. Through close examination of his writing, I define the identifying features of each phase as well as their relationship to other phases. Further, I examine Cowley\u27s use of phases of place perception. One use is generational identification, allowing Cowley to differentiate his literary generation from those coming both before and after. Similar to this idea is the use of place perception to identify a certain time period. By linking place and ideology, Cowley metonymically references a certain set of experiences. The role of place perception as a metonymic identifier is drawn from the idea that place perception serves as a guide to background knowledge for the reader. An important aspect of its use as a guide is the establishment of common experience between Cowley and his audience. Finally, I explain the use of place perception as a mechanism for developing story. While I include Cowley\u27s own ideas concerning generations and the cycle of Adventure and Exile, the main assertion of my investigation is that he presents four distinct phases of place perception. Also, this study presents various ways in which Cowley uses place perception as an organizing theme in his works. Further, while he describes many of his experiences as attempts to disassociate from place, place perception is, paradoxically, at all times central to his thinking. Cowley uses various aspects of place and place perception in such a way that his own ideas of identity are inextricably tied to it. Ultimately, his life, as presented through his literature, illustrates the passage from naive childhood to nostalgic reflection

Feeling the pressure: Differences in blood pressure among working undergraduate students

Studies have shown that being employed while pursuing post-secondary education may lead to higher levels of perceived stress and unhealthy behaviours. The current study involved a hierarchical regression model to analyze both perceived stress and blood pressure (BP) as a function of the number of hours worked per week (HW). Seventy-four undergraduate students from the from the University of Windsor completed measures of perceived stress, coping, physical activity, and daily hassles, and had their BP recorded after ten minutes of rest. There was a correlation between HW and systolic BP (r = .23, p = .04). Problem-focused coping was negatively associated with levels of perceived stress (r = -.23, p \u3c .05), whereas emotion-focused coping was positively associated (r = -.57, p \u3c .001). Energy drink users had higher HW than non-users (t = 2.14, p \u3c .05). There was no change in BP from before and after questionnaire administration