Rift Valley Fever Epidemiology, Surveillance, and Control: What Have Models Contributed?

Background: Rift Valley fever (RVF) is an emerging vector-borne zoonotic disease that represents a threat to human health, animal health, and livestock production, particularly in Africa. The epidemiology of RVF is not well understood, so that forecasting RVF outbreaks and carrying out efficient and timely control measures remains a challenge. Various epidemiological modeling tools have been used to increase knowledge on RVF epidemiology and to inform disease management policies.

Exploratory Space-Time Analyses of Rift Valley Fever in South Africa in 2008-2011

Background: Rift Valley fever (RVF) is a zoonotic arbovirosis for which the primary hosts are domestic livestock (cattle, sheep and goats). RVF was first described in South Africa in 1950-1951. Mechanisms for short and long distance transmission have been hypothesised, but there is little supporting evidence. Here we describe RVF occurrence and spatial distribution in South Africa in 2008-11, and investigate the presence of a contagious process in order to generate hypotheses on the different mechanisms of transmission. Methodology/Principal Findings: A total of 658 cases were extracted from World Animal Health Information Database. Descriptive statistics, epidemic curves and maps were produced. The space-time K-function was used to test for evidence of space-time interaction. Five RVF outbreak waves (one in 2008, two in 2009, one in 2010 and one in 2011) of varying duration, location and size were reported. About 70% of cases (n = 471) occurred in 2010, when the epidemic was almost country-wide. No strong evidence of space-time interaction was found for 2008 or the second wave in 2009. In the first wave of 2009, a significant space-time interaction was detected for up to one month and over 40 km. In 2010 and 2011 a significant intense, short and localised space-time interaction (up to 3 days and 15 km) was detected, followed by one of lower intensity (up to 2 weeks and 35 to 90 km). Conclusions/Significance: The description of the spatiotemporal patterns of RVF in South Africa between 2008 and 2011 supports the hypothesis that during an epidemic, disease spread may be supported by factors other than active vector dispersal. Limitations of under-reporting and space-time K-function properties are discussed. Further spatial analyses and data are required to explain factors and mechanisms driving RVF spread. © 2012 Métras et al.

Transmission Potential of Rift Valley Fever virus over the course of the 2010 epidemic in South Africa

A Rift Valley fever (RVF) epidemic affecting animals on domestic livestock farms was reported in South Africa during January-August 2010. The first cases occurred after heavy rainfall, and the virus subsequently spread countrywide. To determine the possible effect of environmental conditions and vaccination on RVF virus transmissibility, we estimated the effective reproduction number (R) for the virus over the course of the epidemic by extending the Wallinga and Teunis algorithm with spatial information. Re reached its highest value in mid-February and fell below unity around mid-March, when vaccination coverage was 7.5%-45.7% and vector-suitable environmental conditions were maintained. The epidemic fade-out likely resulted first from the immunization of animals following natural infection or vaccination. The decline in vector-suitable environmental conditions from April onwards and further vaccination helped maintain R below unity. Increased availability of vaccine use data would enable evaluation of the effect of RVF vaccination campaigns.

Sequence stratigraphy related distribution of diagenetic alterations In Miocene deltaic and shoreface arenites, the Suez Rift, EGYPT.

The distribution of eogenetic alterations in shoreface-offshore and coarse-grained deltaic, calcarenite to hybrid arenites of the Mheiherrat Formation (lower Rudeis), Early Miocene, the Gulf of Suez, Egypt) can be constrained within a sequence stratigraphic framework. The bioclast-rich, shoreface (trangressive systems tract; TST) and shoreface (highstand systems tract; HST) arenites, particularly those below the parasequence boundaries and maximum flooding surface, are cemented by grain-coating microcrystalline, circumgranular isopacheous acicular and columnar, and coarse-crystalline calcite (δ18OVPDB = -3.6 to -0.3 ‰; δ13CVPDB = -2.3 to -0.7 ‰), non-Ferro an dolomite (δ18OVPDB = -3.9 to +0.9‰; δ13CVPDB = -2.5 ‰ to -0.7 ‰), and pyrite. Zeolite, palygorskite and gypsum occur in the HST shoreface arenites, being enhanced by aird climatic condations. The coarse-grained deltaic LST deposits are pervasively cemented by coarse-crystalline, pore-filling calcite and small amounts of microcrystalline calcite (δ18OVPDB = -4.4 to -2.3 ‰; δ13CVPDB = -2.8 to -1.3 ‰) and non-ferroan dolomite (δ18OVPDB = -4.8 to -2.5 ‰; δ13CVPDB = -3.3 to -1.5 ‰). Thus, this study demonstrates that changes in pore-water chemistry, which induced changes in the texture, composition and extent of cementation in the Miocene arenites was controlled by changes in the relative sea level and by the paleo-climatic conditions during deposition of the HST arenites.

Sequence stratigraphy related distribution of diagenetic alterations In Miocene deltaic and shoreface arenites, the Suez Rift, EGYPT.. Available from: https://www.researchgate.net/publication/264545153_Sequence_stratigraphy_related_distribution_of_diagenetic_alterations_In_Miocene_deltaic_and_shoreface_arenites_the_Suez_Rift_EGYPT [accessed Apr 15, 2015].

Research ethics committees: values and power in higher education

The rise of research governance structures in universities has created huge disquiet amongst academic researchers. The unquestioning adoption of a medical model of ethical review based upon positivist methodological assumptions has created for many a mismatch between their own ongoing ethical research practice and the process of obtaining clearance from Research Ethics Committees (REC). This paper examines the issues that have contributed to dissatisfaction with the ethical review model that is prevalent within the modern university. Using examples from the authors’ own experiences, the dynamics of values, interests and power in research governance is examined from multiple perspectives including that of REC member and applicant; lecturer/student supervisor; researcher; and
university administrator. The paper reveals a rift between the values and objectives of the key players in research governance within the modern university and concludes by asking whether differences can be resolved so that a collaborative approach to ethical review may be incorporated into a renewed academic research culture. It is suggested that the alternative is increasing alienation from anything to do with ‘ethics’, with potentially serious consequences for the ethical standards of social research.

3-D micromechanical model for predicting the elastic behaviour of woven laminates

This paper presents an analytical model for the prediction of the elastic behaviour of plain-weave fabric composites. The fabric is a hybrid plain-weave with different materials and undulations in the warp and weft directions. The derivation of the effective material properties is based on classical laminate theory (CLT).

The theoretical predictions have been compared with experimental results and predictions using alternative models available in the literature. Composite laminates were manufactured using the resin infusion under flexible tooling (RIFT) process and tested under tension and in-plane shear loading to validate the model. A good correlation between theoretical and experimental results for the prediction of in-plane properties was obtained. The limitations of the existing theoretical models based on classical laminate theory (CLT) for predicting the out-of-plane mechanical properties are presented and discussed. 

Intralaminar toughness characterisation of unbalanced hybrid plain weave laminates

A numerical and experimental investigation on the mode-I intralaminar toughness of a hybrid plain weave composite laminate manufactured using resin infusion under flexible tooling (RIFT) process is presented in this paper. The pre-cracked geometries consisted of overheight compact tension (OCT), double edge notch (DEN) and centrally cracked four-point-bending (4PBT) test specimens. The position as well as the strain field ahead of the crack tip during the loading stage was determined using a digital speckle photogrammetry system. The limitation on the applicability of the standard data reduction schemes for the determination of intralaminar toughness of composite materials is presented and discussed. A methodology based on the numerical evaluation of the strain energy release rate using the J-integral method is proposed to derive new geometric correction functions for the determination of the stress intensity factor for composites. The method accounts for material anisotropy and finite specimen dimension effects regardless of the geometry. The approach has been validated for alternative non-standard specimen geometries. A comparison between different methods currently available for computing the intralaminar fracture toughness in composite laminates is presented and a good agreement between numerical and experimental results using the proposed methodology was obtained. 

Geographies of Communality, Colonialism, and Capitalism: Ecology and the World-System

Drawing upon recent reworkings of world systems theory and Marx’s concept of metabolic rift, this paper attempts to ground early nineteenth-century Ireland more clearly within these metanarratives, which take the historical-ecological dynamics of the development of capitalism as their point of departure. In order to unravel the socio-spatial complexities of Irish agricultural production throughout this time, attention must be given to the prevalence of customary legal tenure, institutions of communal governance, and their interaction with the colonial apparatus, as an essential feature of Ireland’s historical geography often neglected by famine scholars. This spatially differentiated legacy of communality, embedded within a country-wide system of colonial rent, and burgeoning capitalist system of global trade, gave rise to profound regional differentiations and ecological contradictions, which became central to the distribution of distress during the Great Famine (1845-1852). Contrary to accounts which depict it as a case of discrete transition from feudalism to capitalism, Ireland’s pre-famine ecology must be understood through an analysis which emphasises these socio-spatial complexities. Consequently, this structure must be conceptualised as one in which communality, colonialism, and capitalism interact dynamically, and in varying stages of development and devolution, according to space and time.