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Purpose: To investigate the root and canal morphology of mandibular second molars, including anatomical variations, in a Black South African population using two classification systems. Methods: Cone-beam computed tomography images of 386 teeth were evaluated. The number of roots and canal configurations were categorized using the classifications of Vertucci (with modifications by Sert and Bayirli) and Ahmed et al. (including the modified Melton classification). Relationships between variables were assessed using Fisher’s exact test (P < 0.05). Results: Mandibular second molars were predominantly two-rooted (91.7%). The majority of teeth had three canals including Type IV mesial (41.2%) and Type I (75.1%) distal (Ahmed et al. configuration: ²MDM M² D¹). Three or more canals were present in almost one-fifth of mesial (n = 72/386, 18.6%) and a small number of distal (n = 21/386, 5.4%) roots. Males displayed additional canals more frequently in the distal root (P = 0.02). C-shaped anatomy was found in 5.7%. Among the C-shapes, the most common was Melton’s Type III in the coronal (50%), middle (81%) and apical (72%) thirds. Conclusion: In this population, mandibular second molar teeth exhibited diverse morphology, which would have clinical significance for endodontic practitioners. The Ahmed et al. classification provided a better description than the Vertucci classification. [ABSTRACT FROM AUTHOR]

Purpose: An investigation of the configurations of mandibular premolar roots and canals in a population of Black South Africans. Methods: Cone-beam computed tomography analysis of 772 mandibular premolars was performed, and the premolars were classified according to the systems proposed by Vertucci and Ahmed et al. Root number, canal morphology, age, and sex were recorded. Fisher's exact test was used to determine relationships based on age and sex (P < 0.05). Results: Single roots were seen in the majority of mandibular premolars (97.1%). Single canal configurations (i.e., Vertucci Type 1/Ahmed et al. 1MP1) were observed in 48.5% of first and 81.3% of second mandibular premolars. Mandibular first premolars demonstrated multiple canals in more than half of the sample (51.5%), and C-shaped morphology in more than one-tenth (11.1%). A relationship between sex and the presence of radicular grooves was demonstrated (P = 0.049), males being more likely to demonstrate this feature (P = 0.051). Multiple canals in mandibular first premolars also showed a relationship with sex (P = 0.005), a male predilection being evident (P = 0.007). The Ahmed et al. system proved superior to the Vertucci classification for reporting complex configurations and anatomical variations, although a greater number of unique categories were created. Conclusion: Diverse mandibular premolar root and canal morphology was observed in the studied population. Clinicians must be aware of common morphological features as well as possible anatomical variations in mandibular premolars, as failure to treat complete root canal systems may negatively impact endodontic treatment outcomes. [ABSTRACT FROM AUTHOR]

The timely and efficient administration of rabies vaccinations to animals in rural villages is necessary to attain a state of herd immunity. Efficient sampling of households in a rural village is of utmost importance in reaching the most animals for vaccination, with the least effort, and in the lowest time. This research seeks to both optimise the spatial sampling scheme used to sample households, as well as the route travelled by persons performing door-to-door vaccinations. The walking time in minutes is regarded as the cost of a vaccination scheme and is minimised in this paper. The distribution of houses in a rural village constitutes a spatial point pattern in R 2 , and as such, spatial point pattern analysis techniques as well as some spatial sampling schemes are applied throughout this research. The penultimate aim of this work is to provide policy makers with additional tools to combat rabies, a disease which remains endemic to some countries in West and Central Africa, and Asia. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated the root and canal morphology of the permanent anterior dentition in a Black South African population. Methods: In total 2,343 permanent anterior teeth were evaluated using cone-beam computed tomography images and described according to the Vertucci and Ahmed et al. classifications. Demographic information, root number and internal canal morphology were recorded. Age and sex associations were made using Fisher's exact test (P < 0.05). Results: All anterior teeth were single-rooted (100%). The most frequent configuration in maxillary anteriors was a single canal (Vertucci Type I/1MXA1). In mandibular anteriors, single canal configurations (Type I/1MDA1) predominated, however 36.6% of mandibular central and 33.9% of lateral incisors displayed two canals. Older subjects (>40 years) demonstrated single canals more than younger subjects (P = 0.0004). Females displayed variations more compared to males (P = 0.002). The two classifications were found to be comparable for evaluation of permanent anterior teeth. Complex configurations were better described using the newer system. Conclusion: The permanent anterior teeth of this population exhibited exclusively single roots and diverse internal characteristics. Clinicians should be aware of anatomical variations, particularly in mandibular incisors, as these may result in adverse endodontic outcomes if not taken into consideration by the treating practitioner. [ABSTRACT FROM AUTHOR]

Since the emergence of the novel COVID-19 virus pandemic in December 2019, numerous mathematical models were published to assess the transmission dynamics of the disease, predict its future course, and evaluate the impact of different control measures. The simplest models make the basic assumptions that individuals are perfectly and evenly mixed and have the same social structures. Such assumptions become problematic for large developing countries that aggregate heterogeneous COVID-19 outbreaks in local areas. Thus, this paper proposes a spatial SEIRDV model that includes spatial vaccination coverage, spatial vulnerability, and level of mobility, to take into account the spatial–temporal clustering pattern of COVID-19 cases. The conclusion of this study is that immunity, government interventions, infectiousness and virulence are the main drivers of the spread of COVID-19. These factors should be taken into consideration when scientists, public policy makers and other stakeholders in the health community analyse, create and project future disease prevention scenarios. Such a model has a place for disease outbreaks that may occur in future, allowing for the inclusion of vaccination rates in a spatial manner. [ABSTRACT FROM AUTHOR]

Abstract The Discrete Pulse Transform (DPT) is a nonlinear decomposition of a signal and extracts the structures in a signal at discrete scale levels. This study models the image structure extracted using the DPT as connected components. For this purpose, the Matérn cluster process is being used as it mimics the pulses of the DPT as clusters. In this paper it is applied to a marine image. Inhomogeneity of the pattern is dealt with by means of the fitted intensity. The model residuals exhibited the same pattern as the original image, and a refit resulted in residuals without pattern. The study concludes that the Matérn cluster model well fits the pulses obtained using the DPT and is well able to model the wave pulses of the ocean surface as clusters. This type of hierarchical cluster modelling presents interesting opportunities for simulations via conditioning. [ABSTRACT FROM AUTHOR]

Abstract Kernel smoothing is commonly used in spatial point patterns to construct intensity plots. Kernels allow for visually and subjectively inferring on first-order stationarity. Formal objective tests exist for testing first-order stationarity that assume independence of spatial regions. We propose to extend inference for first-order stationary by using bootstrapping in existing hypothesis tests to deal with the violation of independence. More specifically we compare Poisson intensities from bootstrapped spatial quadrat samples, providing a test for first-order stationarity without violating the assumption of independence of the tests. Five hypothesis testing methods are investigated. The choice of grid mesh size and window shape used in these tests is discussed and guidance is provided through testing the power of the tests. The application considers the household locations in rural villages in Northern Tanzania as an unmarked point pattern. A clear effect of the village sizes on the relation between grid mesh size and confidence intervals of bootstrap sampling is shown. We conclude that bootstrapping provides a novel contribution to inference of first-order stationarity for spatial point patterns. [ABSTRACT FROM AUTHOR]

Background: Project success used to be measured solely in terms of efficiency metrics such as scope, cost and time; however, there are proposals that more attention should be paid to process-related performance factors such as communication. The advent of email has significantly impacted the way the world communicates. Objectives: This study investigates the preference of email communication relative to other communication mediums in project environments and the effect of email communication on feelings of stress and overload in the workplace. Method: A survey with 430 responses was conducted to determine the communication preferences of project practitioners in a typical project. The average rank and frequency response methods were used to analyse the data. Results: The findings indicate that the communication preferences of project practitioners still support the media richness theory and that face-to-face communication is the preferred communication medium in most situations. Despite email being disruptive and a cause of stress, the respondents did not indicate being overloaded because of email. Conclusion: Even though there has been a dramatic shift towards email and electronic communication in projects, face-to-face communication is still the most preferred communication type for most situations. Furthermore, email is perceived as an effective tool to delegate, can be used to build and develop relationships and trust, and is an efficient and effective tool that contributes to project communication success. [ABSTRACT FROM AUTHOR]

Accessibility analyses are conducted for a variety of applications, including urban planning and public health studies. These applications may aggregate data at the level of administrative units, such as provinces or municipalities. Accessibility between administrative units can be quantified by travel distance. However, modelling the distances between all administrative units in a region is computationally expensive if a large number of administrative units is considered. We propose a methodology to model accessibility between administrative units as a homogeneous Markov chain, where the administrative units are states and standardised inverse travel distances act as transition probabilities. Single transitions are allowed only between adjacent administrative units, resulting in a sparse one-step transition probability matrix (TPM). Powers of the TPM are taken to obtain transition probabilities between non-adjacent units. The methodology assumes that the Markov property holds for travel between units. We apply the methodology to administrative units within Tshwane, South Africa, considering only major roads for the sake of computation. The results are compared to those obtained using Euclidean distance, and we show that using network distance yields more reasonable results. The proposed methodology is computationally efficient and can be used to estimate accessibility between any set of administrative units connected by a road network. [ABSTRACT FROM AUTHOR]

The analysis of point patterns on linear networks is receiving current attention in spatial statistics. This refers to the analysis of points in a spatial domain that coincide with a linear network like a road network. The linear network is modelled as a set of lines that are connected at their ends or are intersecting, that is, modelled as mathematical graphs. Limited research so far has been conducted on spatial points that fall on the Euclidean space containing the linear network. This study addresses new steps by exploring points in the vicinity of the network that do not necessarily fall on the linear network. We present a novel method that is motivated by crime locations amongst a road network. The aim is to detect spatial hotspots around a linear network, where crime locations are considered as a point pattern lying in the vicinity of the linear road network. A new connectivity measure is also introduced to define the line segment neighbours of a line segment. The methodology is applied to crime data in Khayelitsha, South Africa. We detect a pattern of crime locations within the network that can be well interpreted. We conclude that our method is well applicable and could potentially help governmental organisations to allocate measures to reduce criminality. [ABSTRACT FROM AUTHOR]