A NEW PUNCHING SHEAR STRENGTHENING TECHNIQUE FOR REINFORCED CONCRETE SLABS AT INTERIOR SLAB-COLUMN CONNECTIONS

In certain situations the punching strength of a connection may become inadequate after construction due to changes of connection geometry from drilling or coring, or from changes of building use, or construction and design errors. The use of shear reinforcement in the form of Shear Bolts is a new approach to strengthening slab-column connections. Reported in this thesis are the results of research on the use of shear bolts for reinforced concrete interior slab-column connections without unbalanced moments. Six slab specimens were tested with different configurations of shear bolts and without shear reinforcement to verify the effectiveness of this method of reinforcement. The central idea is an externally applied shear reinforcing technique that provides strength in shear at par with other conventional reinforcement types on the one hand and offering the distinct advantage and flexibility of external application after construction. A shear bolt consists of an unhardened steel shaft threaded at one end and flared out to form a bearing/anchor surface on the other end. All six specimens were designed to fail in shear before reaching their flexural capacity, two of which were more critical than the others because of the presence of openings simulating utility ducts around the column perimeter. From the tests, comparisons of predicted loads with the failure loads indicated a higher ultimate load for slab reinforced with the bolt system. Similarly, strain measurements from strain gauges attached to the longitudinal steel and deflection profiles of the slab showed that the new method was efficient in increasing the shear capacity of the slabs. In summary, the test program showed that shear bolts are effective in transforming the behaviour of the slab-column connections from a brittle punching shear failure mode to a more ductile flexural one. Deflection profiles at different load stages, and particularly at failure, show increased deflections for specimens reinforced with bolt reinforcements. This indicates an increased ductility at the connection. Similarly, load and flexural reinforcement strain magnitudes show substantial improvements in the strength of the connections

Distinct monkeypox virus lineages co-circulating in humans before 2022

The 2022 global mpox outbreak raises questions about how this zoonotic disease established effective human-to-human transmission and its potential for further adaptation. The 2022 outbreak virus is related to an ongoing outbreak in Nigeria originally reported in 2017, but the evolutionary path linking the two remains unclear due to a lack of genomic data between 2018, when virus exportations from Nigeria were first recorded, and 2022, when the global mpox outbreak began. Here, 18 viral genomes obtained from patients across southern Nigeria in 2019-2020 reveal multiple lineages of monkeypox virus (MPXV) co-circulated in humans for several years before 2022, with progressive accumulation of mutations consistent with APOBEC3 activity over time. We identify Nigerian A.2 lineage isolates, confirming the lineage that has been multiply exported to North America independently of the 2022 outbreak originated in Nigeria, and that it has persisted by human-to-human transmission in Nigeria for more than 2 years before its latest exportation. Finally, we identify a lineage-defining APOBEC3-style mutation in all A.2 isolates that disrupts gene A46R, encoding a viral innate immune modulator. Collectively, our data demonstrate MPXV capacity for sustained diversification within humans, including mutations that may be consistent with established mechanisms of poxvirus adaptation.</p

Emergence and spread of two SARS-CoV-2 variants of interest in Nigeria.

Identifying the dissemination patterns and impacts of a virus of economic or health importance during a pandemic is crucial, as it informs the public on policies for containment in order to reduce the spread of the virus. In this study, we integrated genomic and travel data to investigate the emergence and spread of the SARS-CoV-2 B.1.1.318 and B.1.525 (Eta) variants of interest in Nigeria and the wider Africa region. By integrating travel data and phylogeographic reconstructions, we find that these two variants that arose during the second wave in Nigeria emerged from within Africa, with the B.1.525 from Nigeria, and then spread to other parts of the world. Data from this study show how regional connectivity of Nigeria drove the spread of these variants of interest to surrounding countries and those connected by air-traffic. Our findings demonstrate the power of genomic analysis when combined with mobility and epidemiological data to identify the drivers of transmission, as bidirectional transmission within and between African nations are grossly underestimated as seen in our import risk index estimates

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance.

Investment in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing in Africa over the past year has led to a major increase in the number of sequences that have been generated and used to track the pandemic on the continent, a number that now exceeds 100,000 genomes. Our results show an increase in the number of African countries that are able to sequence domestically and highlight that local sequencing enables faster turnaround times and more-regular routine surveillance. Despite limitations of low testing proportions, findings from this genomic surveillance study underscore the heterogeneous nature of the pandemic and illuminate the distinct dispersal dynamics of variants of concern-particularly Alpha, Beta, Delta, and Omicron-on the continent. Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve while the continent faces many emerging and reemerging infectious disease threats. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Mpox (monkeypox) risk and mortality associated with HIV infection: a national case-control study in Nigeria

INTRODUCTION: Recent outbreaks of mpox are characterised by changes in the natural history of the disease, the demographic and clinical characteristics of the cases, and widening geographical distribution. We investigated the role of HIV and other sexually transmitted infections (STIs) coinfection among cases in the re-emergence of mpox to inform national and global response. METHODS: We conducted a national descriptive and case-control study on cases in the 2017-2019 Nigerian mpox outbreak. Mpox cases were age, sex and geographical area matched each with two randomly selected controls from a representative national HIV/AIDS survey. Logistic regression was used to investigate the association between HIV infection and the risk of mpox acquisition and death. RESULTS: Among 204 suspected mpox cases, 86 were confirmed (median age 31 years (IQR 27-38 years), mostly males (61 cases, 70.9%). Three-fifths of mpox cases had serological evidence of one or more STIs with 27.9% (24/86) coinfected with HIV. The case fatality rate was 9.4% (8/86) and 20.8% (5/24) overall and in HIV positive cases respectively. Mpox cases were more likely to have HIV coinfection compared with an age, gender and geography-matched control group drawn from the general population (OR 45 (95% CI 6.1 to 333.5, p=0.002) and when compared with non mpox rash cases (7.29 (95% CI 2.6 to 20.5, p<0.0001)). HIV coinfection and young age were associated with mortality among mpox cases (aOR 13.66 (95% CI 1.88 to 98.95, p=0.010) and aOR 0.90 (0.82-0.97, p=0.008), respectively). CONCLUSION: HIV infection was associated with a higher risk of contracting and dying from mpox. Children are also at high risk of death. STIs in mpox cases may be suggestive of high-risk sexual behaviours among these individuals