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The alpha complex is a subset of the Delaunay triangulation and is often used in computational geometry and topology. One of the main drawbacks of using the alpha complex is that it is non-monotone, in the sense that if X ⊂ X' it is not necessarily (and generically not) the case that the corresponding alpha complexes satisfy Ar(X) ⊂ Ar(X'). The lack of monotonicity may introduce significant computational costs when using the alpha complex, and in some cases even render it unusable. In this work we present a new construction based on the alpha complex, that is homotopy equivalent to the alpha complex while maintaining monotonicity. We provide the formal definitions and algorithms required to construct this complex. In addition, we analyze the size of this complex in order to argue that it is not significantly more costly to use than the standard alpha complex. [ABSTRACT FROM AUTHOR]

Abstract Humans find reasoning about uncertainty difficult. In decision support systems and software for intelligence analysis, graphical representations are commonly used to display uncertainty. Nevertheless, our understanding of how people use the information presented in graphs displaying uncertainty to make decisions is limited. As many artificial intelligent systems require a human-in-the-loop who is able to actively take part in the analysis process, the understanding of high-level cognition involved in human-graph interaction is essential in the design of better tools for analysis. In this research, we investigate the visual behaviour that is associated with participants responses to problems testing probabilistic reasoning represented through two different visualizations (tree and Venn diagrams). Using the data from visual fixations and transitions, we present a description of different reasoning strategies covering both accurate and inaccurate reasoning for different visualization formats. The results show that gaze behaviour is related to reasoning accuracy. Moreover, this study shows that different graphs representing the same problem evoke different reasoning strategies, suggesting that higher level cognition is influenced by the graphical representation in which uncertainty is encoded. Highlights • We studied probabilistic reasoning in the context of human-graph interaction. • We proposed an eye tracking method to study human reasoning. • Probabilistic reasoning is affected by how uncertainty is graphically encoded. • Gaze behaviour is linked to people performance in Bayesian reasoning tasks. [ABSTRACT FROM AUTHOR]

Humans often struggle to understand conditional probability, which underlies the interpretation of many important procedures including medical tests. Visualisation has proved effective in communicating risk in healthcare settings, but its role in facilitating Bayesian reasoning is complex, with contradictory evidence as to its utility, and a lack of understanding as to how it is best applied. This paper evaluates both established and novel techniques for visualising conditional probabilities, examining not just whether they facilitate understanding, but how people use the way the information is presented to interpret the data. We report a controlled study comparing different visualisations of a well-known Bayesian problem, the mammography problem, to its textual description. We use eye tracking, coupled with a novel technique to measure the reasoning process (which we term the utilisation metric ), alongside measures of efficiency, effectiveness and satisfaction, to reveal cognitive processes underpinning human-graph understanding. The results demonstrate that the rarity of an event strongly affects how far someone's estimation deviates from the true value of the risk, with rare events resulting in a larger deviation than common events. The results also show that the way in which the data is presented affects both speed and accuracy of interpretation, and that people have preferences that cannot be explained by performance data alone. Whilst Venn diagrams appear to be equal to tree diagrams in terms of task performance, people find the latter easier to interpret. Icon arrays, which are commonly used for presenting risk data, are perceived to be particularly poor at conveying information about conditional probabilities. [ABSTRACT FROM AUTHOR]

The use of desktop technologies, opposed to their mobile counterparts, is still predominant in the business domain and daily corporate activities. For complex business tasks, the usability of mobile applications is still perceived as inferior. Nevertheless, mobile computing could support work activities in different ways. This research seeks to explore whether mobile applications, especially sophisticated real-time groupware such as Group Decision Support Systems can match or even outperform their desktop-based counterparts regarding task performance and user satisfaction. To provide a more comprehensive comparison, two widely used web metric frameworks, HEART and PULSE (the former focusing on human behavior and the latter focusing on technology), have been used to evaluate and compare a web-based mobile group decision support app with its desktop counterpart on a chair-led multi-step decision-making process in lab settings and real-world contexts. Moreover, data from web tracking tools and system logs of these two apps have been analyzed to deepen the level of analysis. Therefore, an innovative methodology for usability research combining lab experiments with long-term web observations is proposed. The results have shown that users interacting with the mobile version of the system had a steeper learning curve than users interacting with the desktop one. After a short practice period, participants using the mobile version of the groupware could perform as efficiently as participants using its desktop counterpart. Not only both the mobile and the desktop version of the app were used effectively for the group decision tasks chosen for this study, but also the two versions of the application were rated similarly in terms of user satisfaction. Furthermore, the mobile version had a faster adoption, better engagement, and better retention than its desktop counterpart. Despite an additional groupware middleware layer and a sophisticated user interface rendering layer, both groupware versions have yielded a user-to-user response time sufficient for real-time group interactions. These results convey important implications: as society is quickly moving towards mobile computing, web-based mobile technologies can now support multi-step group decision-making tasks. [ABSTRACT FROM AUTHOR]

Does reading a description of an artwork affect how a person subsequently views it? In a controlled study, we show that in most cases, textual description does not influence how people subsequently view paintings, contrary to participants' self-report that they believed it did. To examine whether the description affected transition behaviour, we devised a novel analysis method that systematically determines Units of Interest (UOIs), and calculates transitions between these, to quantify the effect of an external factor (a descriptive text) on the viewing pattern of a naturalistic stimulus (a painting). UOIs are defined using a grid-based system, where the cell-size is determined by a clustering algorithm (DBSCAN). The Hellinger distance is computed for the distance between two Markov chains using a permutation test, constructed from the transition matrices (visual shifts between UOIs) of the two groups for each painting. Results show that the description does not affect the way in which people transition between UOIs for all but one of the paintings -- an abstract work -- suggesting that description may play more of a role in determining transition behaviour when a lack of semantic cues means it is unclear how the painting should be interpreted. The contribution is twofold: to the domain of art/curation, we provide evidence that descriptive texts do not effect how people view paintings, with the possible exception of some abstract paintings; to the domain of eye-movement research, we provide a method with the potential to answer questions across multiple research areas, where the goal is to determine whether a particular factor or condition consistently affects viewing behaviour of naturalistic stimuli. [ABSTRACT FROM AUTHOR]

We consider the multi-user lossy source-coding problem for continuous alphabet sources. In a previous work, Ziv proposed a single-user universal coding scheme which uses uniform quantization with dither, followed by a lossless source encoder (entropy coder). In this paper, we generalize Ziv’s scheme to the multi-user setting. For this generalized universal scheme, upper bounds are derived on the redundancies, defined as the differences between the actual rates and the closest corresponding rates on the boundary of the rate region. For the mean-square error distortion measure, it is shown that this scheme can achieve redundancies of no more than 0.754 b per sample for each user. These bounds are obtained without the knowledge of the multi-user rate region, which is an open problem in general. As a direct consequence of these results, the inner and outer bounds on the rate-distortion achievable region are obtained. [ABSTRACT FROM PUBLISHER]

In this paper, we introduce new lower bounds on the distortion of scalar fixed-rate codes for lossy compression with side information available at the receiver. These bounds are derived by presenting the relevant random variables as a Markov chain and applying generalized data-processing inequalities a la Ziv and Zakai. We show that by replacing the logarithmic function with other functions, in the data-processing theorem we formulate, we obtain new lower bounds on the distortion of scalar coding with side information at the decoder. The usefulness of these results is demonstrated for uniform sources and the convex function Q(t)=t^1-\alpha , \alpha >1. The bounds in this case are shown to be better than one can obtain from the Wyner–Ziv rate-distortion function. [ABSTRACT FROM AUTHOR]

We present adaptive on-line schemes for lossy encoding of individual sequences, under the conditions of the Wyner-Ziv (WZ) problem. In the first part of this paper, a set of fixed-rate scalar source codes with zero delay is presented. We propose a randomized on-line coding scheme, which achieves asymptotically (and with high probability), the performance of the best source code in the set, uniformly over all source sequences. Efficient algorithms for implementing this scheme for small and large sets of encoders are presented. In the second part of this work, we generalize our results to the case of variable-rate coding. A set of variable-rate scalar source codes is presented. This time, the performance is measured by the Lagrangian Cost (LC), which is defined as a weighted sum of the distortion and the length of the encoded sequence. Efficient algorithms for implementing the generalized on-line coding scheme are presented. We then consider the special case of lossless variable-rate coding. An on-line scheme which uses Huffman codes is presented. We show that this scheme can be implemented efficiently using the same graphic methods from the first part. Finally, combining the results from former sections, we build a generalized efficient algorithm for a structured set of variable-rate encoders. [ABSTRACT FROM AUTHOR]

Hay fever affects people differently and can change over a lifetime, but data is lacking on how environmental factors may influence this. This study is the first to combine atmospheric sensor data with real-time, geo-positioned hay fever symptom reports to examine the relationship between symptom severity and air quality, weather and land use. We study 36145 symptom reports submitted over 5 years by over 700 UK residents using a mobile application. Scores were recorded for nose, eyes and breathing. Symptom reports are labelled as urban or rural using land-use data from the UK's Office for National Statistics. Reports are compared with AURN network pollution measurements and pollen and meteorological data taken from the UK Met Office. Our analysis suggests urban areas record significantly higher symptom severity for all years except 2017. Rural areas do not record significantly higher symptom severity in any year. Additionally, symptom severity correlates with more air quality markers in urban areas than rural areas, indicating that differences in allergy symptoms may be due to variations in the levels of pollutants, pollen counts and seasonality across land-use types. The results suggest that a relationship exists between urban surroundings and hay fever symptoms. [ABSTRACT FROM AUTHOR]

• We propose five representative biofeedback visual designs for guided stress management by employing a series of design activities. • We conduct a comprehensive empirical study to compare the effect of five different visual designs on promoting engagement during guided stress management training. • We investigate the strengths and weaknesses of each design and discuss considerations for designing technology-mediated stress management interfaces. The prevalence of functional and affordable wearable biosensors has led to an increase in stress management applications for learning about and improving one's mental health. Previous research suggests that different types of graphical interfaces may evoke diverse user experiences with biofeedback interpretations and related interventions. In this research, we systematically investigate the effect of various biofeedback visual designs on supporting user engagement during a guided stress management practice. Specifically, we hypothesize that certain visual designs will affect user engagement and, thus, the training attention and physiological measures, due to their specific design features. Following a series of design studies, we assess five different styles of visual design and, for each style, we identify a suitable representative (i.e., raw numbers for the numerical style, bar charts for the analytical style, waves for the illustrative style, butterfly drawings for the artistic style, and table lamps for the ambient style). In a controlled within-subject experiment with 35 participants, we assess these five designs through a biofeedback-assisted stress management practice. We find that, overall, visual representation of data increases engagement and, thus, better facilitates stress management training when compared to a numerical display. The analysis through the results suggests that a certain level of abstraction in the interpretation of data encoding helps users move away from being judgmental; whereas animations and transitions augment the experience of being in the present moment. [ABSTRACT FROM AUTHOR]

Brown algal forests provide many ecosystem services but are declining worldwide, prompting a growing number of conservation and restoration efforts. Recent attempts to recover Cystoseira forests are encouraging in the Mediterranean, but whether this is possible in more challenging Atlantic conditions has not yet been investigated. In this study, we assess the feasibility of cultivating Gongolaria nodicaulis by producing ex-situ recruits for reforestation on the Atlantic coast of Morocco. Embryos of G. nodicaulis were cultured on clay tiles for 26 days under controlled conditions without water motion, reaching an average length of 3 mm before being outplanted on the intertidal zone. The transplants were monitored for six months. Recruits experienced high loss rates, approximately 47 % of zygotes within 7 days in culture and 75 % of outplanted seedlings within 10 days in the field. The latter might result from natural self-thinning (competition), but our observations suggested that it was also largely due to the weak attachment of recruits to the tiles resulting from cultivation under calm conditions. Six months after the transplants, the surviving individuals reached the size of wild adult algae (average length of 13.5 cm), and some even became reproductive. Globally, survival rates, growth, physiological condition and fertility in this restoration pilot suggest that ex-situ recruitment and outplanting of G. nodicaulis is a promising approach to recover forests in Atlantic Morocco. [ABSTRACT FROM AUTHOR]

After its creation in 2011 the Brazilian Center for Monitoring and Early Warnings of Natural Disasters – Cemaden, has significantly increased its observational network, monitored municipalities and historical flood and landslide events. However, from 2011 to 2016 the records were not standardized, thus a single integrated analysis of the events were not viable. The compiled information was spread over a wide variety of sources and formats making it difficult to be assessed as a whole. Therefore, this study aimed the development of a method to facilitating the structuring of a national database of flood and landslide events adequately categorized taking into account the type of processes and its characteristics. A set of criteria was created in order to aid analysts to interpret and transcript the original heterogeneous information into a single database and a classified event system based on type and magnitude of the events, accuracy and level of impact. The main sources of information are questionnaires answered by municipalities civil defense, daily reports from Brazilian center for risk and disasters management – CENAD, institution databases, news reports and online media. The available information was translated into the following main parameters: type and date of the event, magnitude, location, time, accuracy of location, accuracy of time, impact (affected people). Additional parameters are also registered if pertinent, like level of rivers or municipality requests for federal support to deal with the event. In our first assessment we considered the events which occurred in 2017. In that year 463 flood events were registered (including flash floods and ponding) and 267 landslides. About 64% of floods were considered small, 28% intermediate and 8% large events. Landslides are also mostly minor events (91%) while 7% were considered intermediate and 2% large events. Flood events resulted in more than a million affected people (1,019,640) and landslides affected approximately one hundred thousand people (94,642). While the number of floods almost double the number of landslides and impacted 10 times more people, landslides caused virtually the same number of fatalities – 24 deaths by landslides and 23 deaths by floods. The most of events (594) took place from January to May and November/December - 2017 - which corresponds to the rainy season in Brasil. From June to October they were registered only 137 events mainly on North and part of Northeast region where the rainy season occurs those months. Although improvements are still required the database is growing permanently since the monitoring teams that feed the system work uninterruptedly on six hour shifts 24 hours a day, seven days a week. The biggest challenge on structuring a national catalog encompassing different types of hydrological disasters in Brazil, which should include small events, consists in reducing uncertainties derived from a wide range of information in terms of availability, detailing, typology and terminology of processes, magnitude, time and location precision and associated impacts. [ABSTRACT FROM AUTHOR]

Abstract The diversity and structure of epiphytic macrofaunal assemblages on the introduced invasive brown macroalga Sargassum muticum and native fucoids (Bifurcaria bifurcata, Cystoseira humilis, Cystoseira tamariscifolia and Sargassum vulgare) were compared over a 1-year period in intertidal rockpools on the Atlantic coast of Morocco. In comparison with the epiphytic fauna associated to other macroalgae from European shores, we found that the associated epiphytic macrofauna was moderately diverse (H'<3 bit) and was mainly dominated by gastropods and crustaceans. The most abundant taxa were the isopod Dynamene bidentata and the gastropods Steromphala umbilicalis and Steromphala pennanti. The epiphytic macrofauna community structure differed slightly between the invader and the natives along the year. There was significant temporal variation in the total number of individuals of epiphytic macrofauna per thallus dry weight for the associated epifauna with the highest abundance found on C. tamariscifolia in the spring. The composition of the epiphytic macrofauna on each macroalga species was fairly constant over time. Overall, our results demonstrated that the mobile epiphytic macrofauna on this rocky area showed low macroalgal specificity. They also revealed that the invader S. muticum supports similar epiphytic macrofaunal communities as the native brown macroalgae and provides an additional appropriate habitat for a generalist associated epiphytic macrofauna. [ABSTRACT FROM AUTHOR]

SUMMARY The Japanese brown seaweed Sargassum muticum, recently invaded several shorelines worldwide including the Atlantic coast of Morocco with large well-established populations. Within the framework of a sustainable strategy to control this invasive seaweed, we report on extraction yield, spectroscopic characterization and rheological properties of alginate, a commercially valuable colloid, from harvested biomass of S. muticum. Extraction yield was about 25.6% on dry weight basis. Infrared spectroscopy analysis shows that the obtained Fourier transform infrared spectra of the extracted biopolymer exhibit strong similarities with that of the commercial alginate. Furthermore, Proton nuclear magnetic resonance spectroscopy revealed that S. muticum alginate has almost equal amounts of β-D-mannuronic acid (M; 49%) and α-L-guluronic acid (G; 51%) with an M/G ratio of 1.04 and a high content of heteropolymeric MG GM diads suggesting a sequence distribution of an alternated polymer type. Rheological measurements were performed at different sodium alginate concentrations, temperatures and shear rates. The hydrocolloid exhibited pseudoplastic behavior and showed shear thinning, particularly at high solution concentration and low temperature which is consistent with the rheological behavior reported for commercial alginates. Considering the abundance of S. muticum in the Northwestern Atlantic coast of Morocco and the quality of the extracted hydrogel, this invasive species could be considered as a potential source of alginates. [ABSTRACT FROM AUTHOR]

The article presents a study which examined the therapeutic effect of active music therapy (AMT) on behavioral disturbances (BPSD) of a person with dementia (PWD). The management induce stress and burden of dementia in family caregivers is also examined. The variables considered include the role of a facilitator of in bridging communication between PWD and FC, gender of both the FC and PWD and psychological assessment.

In the present study, alginate yield and composition were investigated during the seasonal life cycle of the alien brown alga Sargassum muticum harvested from the Atlantic coast of Morocco. Alginate yield ranged from 11.14% in winter to 25.62% in spring/early summer, coinciding with maximum vegetative growth. Monthly monitoring of the alginate block structure showed that the highest mannuronate (M)/guluronate (G) ratio was recorded during the maximum development of S. muticum, before sexual maturity and during resumption of vegetative growth, giving maximum flexibility to the alga. The unusually high molar monad fractions (FG) and dyad fractions (FGG) of guluronic acid in late summer/early autumn appeared to be related to stiffness of senescent thalli. Rheological characterisation showed that the alginate of S. muticum exhibited pseudoplastic behaviour, with the highest apparent viscosities measured in late summer/early autumn when the G blocks dominated the alginate structure. This study suggests that S. muticum could be exploited as an alginophyte for commercial applications. The best harvest time is May-June, which corresponds to the highest alginate yield, maximum thallus growth, and largely completed sexual reproduction, ensuring sustainable exploitation of the species. [ABSTRACT FROM AUTHOR]

The inhibition effect of the invasive brown seaweed Sargassum muticum extract (ESM), harvested from the Atlantic coast of Morocco, against the corrosion of carbon steel (CS) in 1 M HCl medium was studied for the first time using gravimetric, electrochemical and surface techniques. The methanolic crude extract of Sargassum muticum (ESM) is rich in alginate biopolymer. The evaluation corrosion tests showed that this algal extract acts as a good mixed corrosion inhibitor for CS substrate in 1 M HCl since inhibition efficiency of 97% was reached with 1 g/L of ESM at 303 K. AC impedance findings showed that the seaweed extract adding in the corrosive electrolyte increases the polarization resistance and conversely decreases the charge capacitance at the interface. Adsorption of ESM on the substrate surface followed the Langmuir adsorption isotherm. X-ray photoelectron spectroscopy analyses (XPS) demonstrated that the corrosion inhibition mechanism of CS substrate in 1 M HCl environment by the investigated algal extract is typical of the chemisorption process and the protective barrier is mainly formed by the adsorbed biological macromolecules. • The Sargassum muticum extract (ESM) is an effective biological inhibitor for the carbon steel corrosion in 1 M HCl. • The adsorption of ESM biological macromolecules on the steel surface is best described by the Langmuir model. • ESM is chemisorbed on the steel surface. • XPS analysis has provided the composition of adsorbed protective layer on the steel surface. [ABSTRACT FROM AUTHOR]

Bees play a crucial role as natural pollinators, ensuring the maintenance and stability of the world's biodiversity and agricultural crops. Native bees in neotropical regions belong to the Meliponini tribe, a larger group that differs significantly in behavior and biology from honeybees (e.g., Apis mellifera) and solitary bees (e.g., Osmia spp.). Hence, the exposure and effects of pesticides is also likely to vary among these different species. The aim of this study was to develop an analytical method to determine the presence of the neonicotinoid clothianidin in the Brazilian native stingless bee Tetragonisca angustula (local common name: Jataí). The method used for the chemical analysis involved a QuEChERS technique combined with UHPLC-MS/MS analysis. The developed method was subsequently used to analyze collected field samples. In addition, the acute toxicity of the pesticide to T. angustula was evaluated in a laboratory bioassay evaluating both lethal and sublethal endpoints. The analytical method was successfully developed with detection and quantification limits of 1.55 and 5 μg L−1, respectively, along with a linear range of 1–5 ng mL−1. Clothianidin was detected in environmental samples (9.2–32.9 ng g−1), and the exposure experiments demonstrated acute oral toxicity to adults of T. angustula , (24 h-LD 50 of 0.16 ng a.i./bee), as well as no significative interference in acetylcholinesterase activity. Considering the obtained toxicity endpoints for T. angustula and those reported in the literature for other bee species, this study revealed that T. angustula is more (lethally) sensitive to clothianidin than other bee species, including those commonly used in environmental risk assessment studies. This thus also supports the call for using native test species in (regional) risk assessment evaluations. [Display omitted] • Optimized and validated method for the determination of clothianidin in native bees. • Determination of the oral susceptibility of Tetragonisca angustula to clothianidin. • Quantification of the lethal concentration doses of clothianidin in native bees. [ABSTRACT FROM AUTHOR]

Background: This study reports for the first time the presence of the Lusitanian ampeliscid amphipod Ampelisca lusitanica Bellan-Santini & Marques, 1986 in the northwestern Atlantic coast of Morocco. Methods: Specimens were collected in January 2015 from intertidal rock pools along the El Jadida shoreline associated with the brown algae Bifurcaria bifurcata and Sargassum muticum. Results: Systematic description of the species is presented, as well as a discussion of its ecological and geographical distribution. Conclusion: This new finding extends the geographical distribution from the Lusitanian (Europe) to the Mauritanian (Africa) region and increases knowledge of the ecology and the global distribution of A. lusitanica found, previously, only on Portuguese and Spanish coasts. [ABSTRACT FROM AUTHOR]

Alginates are widely used as gelling agents in textile print pastes, medical industries, impression material in dentistry, and anticoagulant material in toothpaste. In the present study, the content and spectroscopic characterization (1H NMR and FT-IR) of the sodium alginates were investigated in the eight brown seaweeds Sargassum muticum, Fucus vesiculosus f. volubilis, Carpodesmia tamariscifolia, Bifurcaria bifurcata, Laminaria ochroleuca, Cystoseira humilis, Saccorhiza polyschides, and Fucus guiryi harvested from the NW Atlantic coast of Morocco. The results proved that the most studied algae depicted alginate yields higher than 18% dry weight. The FT-IR analysis showed that the spectra of the extracted alginates exhibited significant similarities to the commercial alginate from Sigma-Aldrich. The 1H NMR spectroscopy indicated that the extracted alginates have a high content of β-d-mannuronic (M) than α-l-guluronic acid (G) with M/G ratio values ranging from 1.04 to 4.41. The homopolymeric fractions FMM are remarkably high compared to the FGG and heteropolymeric fractions (FGM = FMG) especially for F. guiryi, C humilis, C. tamariscifolia, L. ochroleuca, and S. polyschides. Nevertheless, the heteropolymeric fractions (FGM/FMG) are quite abundant in the alginates of S. muticum, F. vesiculosus f. volubilis, and B. bifurcata accounting for more than 52% of the polymer diads. Based on these results, the investigated algal species (except Fucus guiryi and Bifurcaria bifurcata) could be regarded as potential sources of alginates for industrial uses. [ABSTRACT FROM AUTHOR]