Hasil untuk "History of Africa"

James Ferguson

Once lauded as the wave of the African future, Zambia's economic boom in the 1960s and early 1970s was fueled by the export of copper and other primary materials. Since the mid-1970s, however, the urban economy has rapidly deteriorated. Focusing on the experiences of mineworkers in the Copperbelt region, James Ferguson traces the failure of standard narratives of urbanization and social change to make sense of the Copperbelt's recent history. Perspectives on Southern Africa £2150 cloth, £10.95 paper

R. Early, Pablo González-Moreno, S. Murphy et al.

Fall armyworm, Spodoptera frugiperda, is a crop pest native to the Americas, which has invaded and spread throughout sub-Saharan Africa within two years. Recent estimates of 20-50% maize yield loss in Africa suggest severe damage to livelihoods. Fall armyworm is still infilling its potential range in Africa, and could spread to other continents. In order to understand fall armyworm’s year-round, global, potential distribution, we used evidence of the effects of temperature and precipitation on fall armyworm life-history, combined with data on native and African distributions to construct Species Distribution Models (SDMs). Fall armyworm has only invaded areas that have a climate similar to the native distribution, validating the use of climatic SDMs. The strongest climatic limits on fall armyworm’s year-round distribution are the coldest annual temperature and the amount of rain in the wet season. Much of sub-Saharan Africa can host year-round fall armyworm populations, but the likelihoods of colonising North Africa and seasonal migrations into Europe are hard to predict. South and Southeast Asia and Australia have climate that would permit fall armyworm to invade. Current trade and transportation routes reveal Australia, China, India, Indonesia, Malaysia, Philippines, and Thailand face high threat of fall armyworm invasions originating from Africa.

P. Curtin

F. Keith Barker, A. Cibois, Peter Schikler et al.

G. Standing

Throughout history, class-based revolt has led to the creation of charters of demands, from the Magna Carta to South Africa's Freedom Charter. It is now time for a Precariat Charter.

J. Comaroff, J. Comaroff

Luísa Pereira, L. Mutesa, P. Tindana et al.

The ATLAS collaboration, G. Aad, E. Aakvaag et al.

Abstract A search is performed for dark matter particles produced in association with a resonant pair of Higgs bosons using 140 fb −1 of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the Large Hadron Collider. This signature is expected in some extensions of the Standard Model predicting the production of dark matter particles, and is interpreted in terms of a dark Higgs model containing a Z′ mediator in which the dark Higgs boson s decays into a pair of Higgs bosons. The dark Higgs boson is reconstructed through final states with at least three b-tagged jets, produced by the pair of Higgs boson decays, in events with significant missing transverse momentum consistent with the presence of dark matter. The observed data are found to be in good agreement with Standard Model predictions, constraining scenarios with dark Higgs boson masses within the range of 250 to 400 GeV and Z′ mediators up to 2.3 TeV.

Karolina Jakaitė, Karina Simonson

The conference Art Beyond the Politics: Africa and the ‘Other’ Europe during the Cold War, planned by the Vilnius Academy of Arts in 2022, was intended to explore the often-overlooked cultural exchanges between Central-Eastern Europe and Africa during the Cold War era. Its goal was to address a significant gap in art historical research by examining both actual and imagined connections between these regions, challenging the prevailing narratives that predominantly focus on Western Europe and the United States. Unfortunately, the outbreak of war in Ukraine rapidly disrupted these plans. Global academic networks were suddenly fractured, and scholars found themselves increasingly divided along national lines. Panels, collaborations, and exchanges that had been in preparation were postponed or cancelled, underscoring how geopolitical crises continue to shape the conditions of intellectual work. This special issue of Acta Academiae Artium Vilnensis seeks to advance the conference’s objectives despite these disruptions, providing a platform for scholarly engagement with the intersections of art, politics, and cultural exchange between Africa and the ‘Other’ Europe during the Cold War. This issue brings together the work of twelve authors, whose papers engage with a wide range of questions, insights, and perspectives. Each contribution offers a unique approach to understanding the cultural, political and artistic intersections between Africa and the Central-Eastern Europe during the Cold War. Collectively, the papers illuminate both historical connections and conceptual frameworks, providing new analyses, critical reflections, and, in some cases, tentative answers to long-standing questions in art history and cultural studies.

Zahra Mirzaiyan, Pierfrancesco Siena, Pasquale Claudio Africa et al.

This work develops a rigorous numerical framework for solving time-dependent Optimal Control Problems (OCPs) governed by partial differential equations, with a particular focus on biomedical applications. The approach deals with adjoint-based Lagrangian methodology, which enables efficient gradient computation and systematic derivation of optimality conditions for both distributed and concentrated control formulations. The proposed framework is first verified using a time-dependent advection-diffusion problem endowed with a manufactured solution to assess accuracy and convergence properties. Subsequently, two representative applications involving drug delivery are investigated: (i) a light-triggered drug delivery system for targeted cancer therapy and (ii) a catheter-based drug delivery system in a patient-specific coronary artery. Numerical experiments not only demonstrate the accuracy of the approach, but also its flexibility and robustness in handling complex geometries, heterogeneous parameters, and realistic boundary conditions, highlighting its potential for the optimal design and control of complex biomedical systems.

D. Ferranti, Guillermo E. Perry, F. Ferreira et al.

Michael Nwankpa

From its inception, the different components that constitute Nigeria have lived in mutual fear and suspicion of one another. The British colonial government, through its racialised and politicized system of indirect rule, sowed the seed of discord among the different ethnic groups and regions such that even before gaining independence in 1960, both the majority and minority ethnic groups were sceptical of the capacity of an independent Nigeria in protecting their interests and rights. The religious, linguistic, socio-cultural and political fault lines among Nigeria’s plural society have created tension and conflict throughout its existence as a political unit. This has often led to secessionist and self-determination drives and movements that reached their peak less than a decade after independence (1967-70) with Nigeria experiencing a bitter and costly civil war with the Igbo separatist nation of Biafra. Although Nigeria survived the breakup attempt, it continues to face threats of secession that manifest even at the sub-group level. The injustices that are ingrained in Nigeria’s political system remain a strong push factor, but in many cases the secessionist drives are elites’ manipulation to further their own interests and political survival. Based on the resurgence of secessionism in Nigeria, this article critically examines the politics involved in secession in Nigeria as well as the dynamic nature of selected secessionist movements, comparing or charting the trajectories from historical to contemporary secessionist movements.

Pierfrancesco Siena, Paquale Claudio Africa, Michele Girfoglio et al.

This chapter provides an extended overview about Reduced Order Models (ROMs), with a focus on their features in terms of efficiency and accuracy. In particular, the aim is to browse the more common ROM frameworks, considering both intrusive and data-driven approaches. We present the validation of such techniques against several test cases. The first one is an academic benchmark, the thermal block problem, where a Poisson equation is considered. Here a classic intrusive ROM framework based on a Galerkin projection scheme is employed. The second and third test cases come from real-world applications, the one related to the investigation of the blood flow patterns in a patient specific coronary arteries configuration where the Navier Stokes equations are addressed and the other one concerning the granulation process within pharmaceutical industry where a fluid-particle system is considered. Here we employ two data-driven ROM approaches showing a very relevant trade-off between accuracy and efficiency. In the last part of the contribution, two novel technological platforms, ARGOS and ATLAS, are presented. They are designed to provide a user-friendly access to data-driven models for real-time predictions for complex biomedical and industrial problems.

Surabhi Rathore, Pasquale Claudio Africa, Francesco Ballarin et al.

This paper presents a projection-based reduced order modelling (ROM) framework for unsteady parametrized optimal control problems (OCP$_{(μ)}$s) arising from cardiovascular (CV) applications. In real-life scenarios, accurately defining outflow boundary conditions in patient-specific models poses significant challenges due to complex vascular morphologies, physiological conditions, and high computational demands. These challenges make it difficult to compute realistic and reliable CV hemodynamics by incorporating clinical data such as 4D magnetic resonance imaging. To address these challenges, we focus on controlling the outflow boundary conditions to optimize CV flow dynamics and minimize the discrepancy between target and computed flow velocity profiles. The fluid flow is governed by unsteady Navier--Stokes equations with physical parametric dependence, i.e. the Reynolds number. Numerical solutions of OCP$_{(μ)}$s require substantial computational resources, highlighting the need for robust and efficient ROMs to perform real-time and many-query simulations. Here, we aim at investigating the performance of a projection-based reduction technique that relies on the offline-online paradigm, enabling significant computational cost savings. The Galerkin finite element method is used to compute the high-fidelity solutions in the offline phase. We implemented a nested-proper orthogonal decomposition (nested-POD) for fast simulation of OCP$_{(μ)}$s that encompasses two stages: temporal compression for reducing dimensionality in time, followed by parametric-space compression on the precomputed POD modes. We tested the efficacy of the methodology on vascular models, namely an idealized bifurcation geometry and a patient-specific coronary artery bypass graft, incorporating stress control at the outflow boundary, observing consistent speed-up with respect to high-fidelity strategies.

S. O Adebusola, P. A Owolawi, J. S Ojo et al.

Optical Communication in Free Space (FSO) bids more radio bandwidth, operates under a gratis license, and has a lower startup cost as compared to Radio Frequency (RF). Nonetheless, its vulnerability to variations in atmospheric meteorological circumstances is a concern. Ultimately, the purpose of this study is to use Principal Component Analysis (PCA) with Artificial Neural Networks (ANN) to design a QoS prediction model for a terrestrial FSO communication connection. To accomplish the specified goal, meteorological data such as visibility, wind speed, and altitude were collected from the Weather Services in South Africa (SAWS) archive during a ten-year duration at five different locations: George, Johannesburg, Kimberly, Bloemfontein, and Polokwane. The eigenvalues of the first Principal Component (PC1) and the second Principal Component (PC2) in the PCA across the stations Bloemfontein, Johannesburg, Kimberly, George, and Polokwane are 7.624 and 1.020, 7.234, and 0.984, 6.204 and 1.723, 7.354 and 0.876, and 7.104 and 0.865, respectively, demonstrating that, they are kept as QoS variables to train the Artificial Neural Network (ANN) model as they provide the most compelling interpretation of the original variable data. The RMSE values of every proposed model across all the study locations are 0.1437, 0.2131, 0.2329, 0.1101, and 0.1977, respectively. Based on the RMSE, the proposed performed better over George. A realistic and accurate predictive model is developed for each of the study locations. Thus, the developed model will serve as a valuable tool for maintaining good QoS in FSO network services and improving telecom businesses in South Africa.

H. Marais

Tarkie Abebe Walle, Yemataw Zewdu Temachu

Background: The first cases of novel coronavirus (nCoV) were first detected in China and WHO declare a Public Health Emergency of International Concern on January two thousand twenty, and to characterize the outbreak as a pandemic on March two thousand twenty. Since then, COVID-19 is an emerging respiratory infection that was first discovered in Wuhan city, Hubei Province, China. Ethiopia is one of the countries which are affected by the pandemic. Therefore, we aimed to assess the status of private college students' knowledge, attitude, and practice about COVID-19 pandemic disease preventive measures in Gondar. Methods: Institution-based cross-sectional study was conducted among private college students. The study participants were recruited using a simple random sampling technique. Students from five Privet College from year one up to year four involved in this study. Data was collected using self-administered structured questioner with closed ended question. It includes four parts; the first section containing sociodemographic characteristics such as age, sex, educational status and category. The second part elicits about knowledge, the third part includes question concerning attitude and the last part includes practice associated factor questions towards prevention of coved 19. Data were analyzed using SPSS version 22 and presented via tables, figures, and in-text narration. The variables associated with the outcome were identified using multivariable logistic regression. Adjusted odds ratio with a 95 % confidence interval at p-value < 0.05 was fitted to declare the statistical significance. Results: A total of 384 private college students were enrolled in the study which makes a response rate of 100%. About 74.5% of college students had a good level of knowledge, 45.6% of college students had a good level of attitude, and 36.7% of college students had a good level of practice to prevent the COVID-19 pandemic. Marital status and year of study were statistically significant predictors of students’ knowledge level, whereas none of the variables were statistically significant with attitude and practice of COVID-19 prevention. Conclusion: Private College students in Central Gondar town to have a good level of knowledge were as attitude and practice towards COVID-19 was less than half. Marital status and Year of the study were statistically significant predictors of students' knowledge level.

Osoro B. Ogutu

In this paper, we apply the ITU-R P.618-8 model with data from the ITU-R P.837-7, Tropical Rain Measuring Mission (TRMM) and Global Precipitation Mission (GPM) satellite to determine the level of attenuation and available link margin for a LEO system such as Telesat. The specific and predicted attenuation for chosen six candidate ground stations (Abuja, Hartbeesthoek, Cairo, Longonot, Port Louis and Praia) is computed and results presented for 0.001%-1% unavailability time in a year. Setting a link margin of 0.36dB, the available link margin and the best candidate ground station for a LEO system such as Telesat is determined. The approach used can be implemented for other potential ground stations and LEO communication systems over Africa.

Amy J. Spies, Maryna Steyn, Desiré Brits et al.

Radiological diagnostic errors are common and may have severe consequences. Understanding these errors and their possible causes is crucial for optimising patient care and improving radiological training. Recent postmortem studies using an animal model highlighted the difficulties associated with accurate fracture diagnosis using radiological imaging. The present study aimed to highlight the fact that certain fractures are easily missed on CT scans in a clinical setting and that caution is advised. A few such cases were discussed to raise the level of suspicion to prevent similar diagnostic errors in future cases. Records of adult patients from the radiological department at an academic hospital in South Africa were retrospectively reviewed. Case studies were selected by identifying records of patients between January and June 2021 where traumatic fractures were missed during initial imaging interpretation but later detected during secondary analysis or on follow-up scans. Seven cases were identified, and the possible causes of the diagnostic errors were evaluated by reviewing the history of each case, level of experience of each reporting radiologist, scan quality and time of day that initial imaging interpretation of each scan was performed. The causes were multifactorial, potentially including a lack of experience, fatigue, heavy workloads or inadequate training of the initial reporting radiologist. Identifying these causes, openly discussing them and providing additional training for radiologists may aid in reducing these errors. Contribution: This article aimed to use case examples of missed injuries on CT scanning of patients in a South African emergency trauma setting in order to highlight and provide insight into common errors in scan interpretation, their causes and possible means of mitigating them.

R. Morrell