Understanding psychosocial determinants of malaria behaviours in low-transmission settings: a scoping review

BACKGROUND

Recent estimates show progress toward malaria elimination is slowing in many settings, underscoring the need for tailored approaches to fight the disease. In addition to essential structural changes, human behaviour plays an important role in elimination. Engagement in malaria behaviours depends in part on psychosocial determinants such as knowledge, perceived risk, and community norms. Understanding the state of research on psychosocial determinants in low malaria transmission settings is important to augment social and behaviour change practice. This review synthesizes research on psychosocial factors and malaria behaviours in low-transmission settings.

METHODS

A systematic search of peer-reviewed literature and supplemental manual search of grey literature was conducted using key terms and eligibility criteria defined a priori. Publications from 2000-2020 in the English language were identified, screened, and analysed using inductive methods to determine the relationship between the measured psychosocial factors and malaria behaviours.

RESULTS

Screening of 961 publications yielded 96 for inclusion. Nineteen articles collected data among subpopulations that are at increased risk of malaria exposure in low-transmission settings. Purposive and cluster randomized sampling were common sampling approaches. Quantitative, qualitative, and mixed-methods study designs were used. Knowledge, attitudes, and perceived risk were commonly measured psychosocial factors. Perceived response-efficacy, perceived self-efficacy, and community norms were rarely measured. Results indicate positive associations between malaria knowledge and attitudes, and preventive and care-seeking behaviour. Studies generally report high rates of correct knowledge, although it is comparatively lower among studies of high-risk groups. There does not appear to be sufficient extant evidence to determine the relationship between other psychosocial variables and behaviour.

CONCLUSIONS

The review highlights the need to deploy more consistent, comprehensive measures of psychosocial factors and the importance of reaching subpopulations at higher risk of transmission in low transmission contexts. Malaria-related knowledge is generally high, even in settings of low transmission. Programmes and research should work to better understand the psychosocial factors that have been positively associated with prevention and care-seeking behaviours, such as norms, perceived response efficacy, perceived self-efficacy, and interpersonal communication. These factors are not necessarily distinct from that which research has shown are important in settings of high malaria transmission. However, the importance of each factor and application to malaria behaviour change programming in low-transmission settings is an area in need of further research. Existing instruments and approaches are available to support more systematic collection of psychosocial determinants and improved sampling approaches and should be applied more widely. Finally, while human behaviour is critical, health systems strengthening, and structural interventions are essential to achieve malaria elimination goals.

Addressing COVID-19 Rumors and Behaviors Using Theory in Guyana: A Program Case Study

We used a COVID-19 rumor classification tool to rapidly identify, synthesize, and counter misinformation during the COVID-19 pandemic and provide appropriate social and behavior change messaging that would affect relevant preventive and protective behaviors.

Introduction:

To manage the rapid rise of misleading information on the coronavirus disease (COVID-19) during the pandemic, the Breakthrough ACTION project developed a theory-based rumor-tracking system to inform Guyana’s COVID-19 communication campaign.

Methods:

The rumor-tracking project used the extended parallel processing model (EPPM) to identify and categorize rumors reflecting perceived high versus low vulnerability to COVID-19 and high versus low efficacy of engaging in recommended COVID-19 prevention behaviors. The project designed contextually relevant social and behavior change messages, called “MythBusters,” responded to rumor categories with the following objectives: (1) high perceived vulnerability and high efficacy rumors included a call to action; high perceived vulnerability and low efficacy rumors educated about effective and achievable solutions; (3) low perceived vulnerability and high efficacy rumors educated about risk; and (4) low perceived vulnerability and low efficacy rumors educated about risk and effective and achievable solutions.

Results:

Most rumors emanated from regions 4 and 8 (29%). Over two-thirds of the rumors (71%) recurred. Rumors were typically related to COVID-19 treatment or prevention (40%) and transmission (35%). Most rumors (48%) reflected low perceived vulnerability and low efficacy, 29% reflected high perceived vulnerability and low efficacy, 13% reflected low perceived vulnerability and high efficacy, and 10% reflected high perceived vulnerability and high efficacy. The project rapidly developed 12 MythBusters from June through December 2020 and integrated them into the national COVID-19 communication campaign, disseminated via radio, television, and Facebook. Estimates indicate that they have reached most of the target Guyanese population.

Discussion:

The EPPM was a particularly useful tool, giving direction to countering myths with appropriate messaging to affect relevant behaviors. The COVID-19 MythBusters provided the Guyanese public with valid and verifiable information and promoted preventive and protective behaviors.

Human-centered design process and solutions to promote malaria testing and treatment seeking behavior in Guyana hinterlands

Background

Malaria is a persistent public health challenge among miners and other hard-to-reach populations in Guyana’s hinterland, specifically in Regions 1, 7, 8, and 9. Despite an overall decrease in malaria prevalence throughout Guyana, it remains common among mining populations whose work conditions both contribute toward malaria transmission and make it difficult to seek timely, Ministry of Health (MoH) approved malaria testing and treatment services. In an effort to develop innovative approaches to address this public health challenge, an interdisciplinary team of public health professionals, designers, and mining organizations collaborated using a human-centered design (HCD) process facilitated by the USAID-funded Breakthrough ACTION Guyana project in partnership with the MoH.

Methods

This paper describes two phases: [1] Define and [2] Design & Test. In the Define phase, following a literature review, we conducted 108 qualitative interviews with miners, camp managers, trained malaria testers, health workers, and other key stakeholders to understand experiences and challenges when seeking malaria testing and treatment services. These interviews were synthesized into 11 insights on issues such as risk perception, malaria knowledge, preventive behaviors, traditional and self-treatment, adherence to the correct treatment, testing, and coordination and communication gaps. From these insights, during the Design & Test phase, we developed 33 “How might we…?” questions which led to 792 ideas, of which eight emergent concepts were prototyped and refined in the field with 145 miners, camp managers, and stakeholders.

Results

The five final prototypes included: “Little Mosquito, Big Problem” social behavior change campaign; rapid counseling cards; branded malaria testing and treatment services; innovations in treatment adherence; and a participants, content, and logistics approach.

Conclusion

When applying HCD to public health issues, there are both opportunities and challenges to reconcile gaps that may exist between the two disciplines. However, HCD provides additional tools and mindsets to generatively work with migrant and mobile mining communities to encourage malaria testing and treatment services.

A new diversity index

We introduce here a new index of diversity based on consideration of reasonable propositions that such an index should have in order to represent diversity. The behaviour of the index is compared with that of the Gini-Simpson diversity index, and is found to predict more realistic values of diversity for small communities, in particular when each species is equally represented and for small communities. The index correctly provides a measure of true diversity that is equal to the species richness across all values of species and organism numbers when all species are equally represented, as well as Hill's more stringent 'doubling' criterion when they are not. In addition, a new graphical interpretation is introduced that permits a straightforward visual comparison of pairs of indices across a wide range within a parameter space based on species and organism numbers.

Malaria prevention and care seeking among gold miners in Guyana

Despite being a priority population in malaria elimination, there is scant literature on malaria-related behavior among gold miners. This study explores the prevalence and factors influencing malaria prevention, care seeking and treatment behaviors in Guyana gold mining camps. A cross sectional survey was conducted among adult gold miners living in mining camps in the hinterland Regions 1 (Barima-Waini), 7 (Cuyuni-Mazaruni), and 8 (Potaro-Siparuni). Multivariable logistic regressions explored factors associated with miners’ self-report of mosquito net use, prompt care-seeking; self-medication; and testing for malaria. A third of miners used a mosquito net the night preceding the survey and net use was higher among those who believed that net use was the norm in their camp (aOR: 3.11; 95% CI:1.65, 5.88). Less than half (45%) of miners had a fever in the past 12 months, among whom 36% sought care promptly, 48% tested positive for malaria while 54% self-medicated before seeking care. Prompt care-seeking was higher among miners with high malaria knowledge (aOR: 1.44; 95% CI: 1.01, 2.05). Similarly, testing rates increased with secondary education (aOR: 1.71; 95% CI: (1.16, 2.51), high malaria knowledge (aOR: 1.45; 95% CI: 1.02, 2.05), positive beliefs regarding malaria transmission, threat, self-diagnosis, testing and treatment, and, trust in government services (aOR: 1.59; 95% CI (1.12, 2.27) and experience of a prior malaria episode (aOR: 2.62; 95% CI: 1.71, 4.00). Self-medication was lower among male miners (aOR: 0. 52; 95% CI: 0.32, 0.86). Malaria prevention and care seeking behaviors among miners are somewhat low and influenced by mosquito net usage, perceived norms, malaria knowledge and prior episode of confirmed malaria. Study findings have implications for malaria interventions in the hinterland regions of Guyana such as the mass and continuous distribution of insecticide treated nets as well as community case management initiatives using trained malaria testing and treatment volunteers to curb malaria transmission among remote gold mining populations. These include efforts to identify and address gaps in distributing mosquito nets to miners and address miners’ barriers to prompt care seeking, malaria testing and treatment adherence. Targeted social and behavior change messaging is needed on net acquisition, use and care, prompt care-seeking, malaria testing and treatment adherence. Additional efforts to ensure the overall sustainability of the community case management initiative include increased publicity of the community case management initiative among miners, use of incentives to promote retention rates among the community case management volunteer testers and public private partnerships between the Guyana Ministry of Health and relevant mining organizations.

The role of gender in Zika prevention behaviors in the Dominican Republic: Findings and programmatic implications from a qualitative study

Background

Zika remains an epidemiological threat in Latin America, including the Dominican Republic. Although transmitted by the same mosquito as Dengue and Chikungunya, Zika is unique in the potentially harmful consequences for babies born to women infected during pregnancy. Experts highlight the feminization of Zika, in terms of burden of disease and women’s caregiving responsibilities. Understanding gender’s role in Zika prevention, therefore, is key to strengthening current and future programs.

Methodology/Principal findings

This qualitative study, comprised of 12 focus group discussions and eight in-depth interviews, explored gender’s role in Zika among pregnant and non-pregnant women as well as male partners of pregnant women in the Dominican Republic. Topics included perceptions about Zika and perceived feasibility and effectiveness of prevention behaviors (e.g. cleaning water storage containers, using condoms during pregnancy). Researchers applied grounded theory through a process of deductive coding—classifying data around predetermined categories—followed by inductive coding—identifying themes that emerged from coded data. Study findings uncovered three ways in which gender may influence Zika prevention. First, women are largely responsible for household chores—including cleaning water storage containers—with men as assistants. Second, men described their role in the family as the protector. Finally, men and women believed that partners would perceive suggesting condom use or abstinence during pregnancy as a sign of infidelity.

Conclusions

Current/future Zika programs should address knowledge gaps, especially around water storage cleaning techniques and sexual transmission. Programs should also integrate gender into programming in culturally-relevant ways that avoid reinforcing stereotypes. Furthermore, programs should tailor activities for men, women, as well as the couple. In the end, integrating gender in a way that is mindful of the local context while not exploiting existing gender roles is critical for preventing Zika and similar mosquito-borne diseases, both in the Dominican Republic and throughout the region.

Zika is an important epidemiological threat in Latin America, including the Dominican Republic. Because Zika disproportionately affects women, understanding gender’s role in Zika prevention is key to strengthening current and future programs. We explored the role of gender in Zika among men and women in the Dominican Republic. Topics included perceptions about Zika and perceived feasibility/effectiveness of specific Zika-prevention behaviors. We uncovered that women are largely responsible for household chores—including cleaning water storage containers (a primary mosquito vector habitat)—with men as assistants. In addition, men described their role in the family as the protector. Finally, men and women believed that partners would perceive suggesting condom use or abstinence during pregnancy as a sign of infidelity. Study findings offer valuable programmatic implications that integrate gender-related considerations in social and behavior change programs related to Zika and other arboviruses. In the end, integrating gender in a way that is mindful of the local context while not exploiting existing gender roles is critical for reducing the burden of Zika and other similar mosquito-borne diseases in the Dominican Republic and throughout the region.

Evidence-Based Process for Prioritizing Positive Behaviors for Promotion: Zika Prevention in Latin America and the Caribbean and Applicability to Future Health Emergency Responses

To maximize the impact of Zika prevention programming efforts, a prioritization process for social and behavior change programming was developed based on a combination of research evidence and programmatic experience. Prioritized behaviors were: application of mosquito repellent, use of condoms, removing unintentional standing water, covering and scrubbing walls of water storage containers, seeking prenatal care, and seeking counseling on family planning if not planning to get pregnant.

Since the 2015 Zika outbreak in Latin America and the Caribbean, a plethora of behavior change messages have been promoted to reduce Zika transmission. One year after the United States Agency for International Development (USAID) initiated its Zika response, more than 30 variants of preventive behaviors were being promoted. This situation challenged social and behavior change (SBC) programming efforts that require a coordinated response and agreed upon set of focus behaviors to be effective. To support USAID implementing partners in harmonizing prevention efforts to reduce Zika infection, we developed an evidence-based process to identify behaviors with the highest potential to reduce Zika infection and transmission. We compiled a full list of behaviors and selected the most promising for a full evidence review. The review included systematic keyword searches on Google Scholar, extraction of all relevant published articles on Aedes-borne diseases between 2012 and 2018, review of seminal papers, and review of gray literature. We examined articles to determine each behavior's potential effectiveness in preventing Zika transmission or reducing the Aedes aegypti population. We also developed assessment criteria to delineate the ease with which the target population could adopt each behavior, including: (1) required frequency; (2) feasibility of the behavior; and (3) accessibility and cost of the necessary materials in the setting. These behaviors were refined through a consensus-building process with USAID's Zika implementing partners, considering contextual factors. The resulting 7 evidence-based preventive behaviors have high potential to strengthen SBC programming's impact in USAID's Zika response: (1) apply mosquito repellent, (2) use condoms during pregnancy, (3) remove standing water, (4) cover water storage containers, (5) clean/remove mosquito eggs from water containers, (6) seek antenatal care, and (7) seek family planning counseling. This case study documents a flexible process that can be adapted to inform the prioritization of behaviors when there is limited evidence available, as during many emergency responses.

Impact of a behaviour change communication programme on net durability in eastern Uganda

Background

The importance of net durability and the average useful life of a net is increasingly recognized as one of the critical factors that determine how often nets need to be replaced. A study to assess the effect of a net care and repair behaviour change communication (BCC) programme on net durability was conducted in one district in Eastern Uganda with a district in a neighbouring region serving as a comparison. Both districts had received LLINs in September of 2012.

Methods

The intervention was comprised of radio programmes, school and community events. Two-stage cluster sampling household surveys to assess net condition, exposure to BCC messages, and attitudes towards net care and repair were conducted in both districts at baseline (2–3 months post net distribution) and endline (20–21 months post distribution). Net condition was assessed using the proportionate hole index, with nets being classified as either serviceable or too torn.

Results

The intervention led to an additional 31.2 % increased exposure to net care and repair messages in the intervention district. Respondents in the intervention district had a more positive attitude towards net care and repair (32 % of respondents were classified as having a very positive attitude compared to 10 % in the comparison district), which was positively associated with the number of channels through which messages had been received (P < 0.001). Nets belonging to respondents with a very positive attitude were more often categorized as serviceable (80.2 %) compared to respondents with a poor/average attitude (66.4 %; odds ratio: 2.05, P = 0.028); however, this was only observed for the net brand with the greater physical integrity. Additionally, socio-economic status was a significant predictor of net condition. Although nets in the intervention district had significantly more repairs done per net, the act of repairing alone did not improve net condition.

Conclusions

In conclusion, the evaluation showed that the BCC programme resulted in improved knowledge and attitudes towards care and repair, which impacted positively on net condition. Repairs alone were not sufficient to improve net condition. Additional research on which care behaviours and attitudes are most associated with improved net condition would help BCC planners hone their campaigns.

Impact of a behaviour change intervention on long-lasting insecticidal net care and repair behaviour and net condition in Nasarawa State, Nigeria

BACKGROUND

While some data on net durability have been accumulating in recent years, including formative qualitative research on attitudes towards net care and repair, no data are available on how the durability of a net is influenced by behaviour of net maintenance, care and repair, and whether behavioural change interventions (BCC) could substantially impact on the average useful life of the net.

METHODS

The study used an intervention-control design with before-after assessment through repeated cross-sectional household surveys with two-stage cluster sampling following Nasarawa State's December 2010 mass campaign. All campaign nets were 100-denier polyester, long-lasting insecticidal nets (LLIN). Baseline, midline, and endline surveys occurred at one-year intervals, in March 2012, March 2013, and April 2014, respectively. Outcome measures were the proportion of confirmed campaign nets with observed repairs, and the proportion in serviceable condition, measured with proportionate hole index (pHI) and according to WHO guidelines.

RESULTS

For all respondents, exposure to BCC messages was strongly correlated with increased positive attitude towards care and repair, and increases in attitude were positively correlated with observed net repairs, and with the proportion of nets in serviceable condition. In a multivariate regression model, positive care and repair attitude (OR 6.17 p = 0.001) and level of exposure (1 source: OR 4.00 p = 0.000; 3 sources: OR 9.34 p = 0.000) remained the most significant predictors of net condition, controlling for background and environmental factors. Nets that were tied up had 2.70 higher odds of being in serviceable condition (p = 0.001), while repairs made to nets were not sufficient to improve their pHI category. Estimated median net lifespan was approximately one full year longer for nets in households with a positive compared to a negative attitude.

CONCLUSION

Exposure to multiple channels of a comprehensive BCC intervention was associated with improved attitude scores, and with improved net condition at endline. It is possible for BCC interventions to change both attitudes and behaviours, and to have an important effect on overall median net lifespan. Care and repair messages are easily incorporated into existing malaria BCC platforms, and will help contribute to improved net condition, providing, in principle, more protection from malaria.

Microstructural Investigation of the Oxide Scale on Zr-2.5NB and its Interface with the Alloy Substrate

Oxidized Zr-2.5Nb is being developed as an articular bearing surface for the femoral component in total joint arthroplasty. It has so far demonstrated superior wear performance against ultrahigh molecular weight polyethylene (UHMWPE) with respect to traditional articulating materials such as Co-Cr-Mo alloys. In this investigation, we used thermogravimetric analysis, transmission electron microscopy, and in situ x-ray diffraction techniques to study the microstructure and stress state of the oxide scale grown on Zr-2.5Nb.

The oxidation temperature not only determines the kinetics of oxidation but the morphology of the various oxidation products. We have identified the oxidation products of both phases of the two phase alloy and correlated them with the original alloy microstructure. These include not only monoclinic zirconia but also small amounts of tetragonal zirconia and a mixed oxide phase combining both zirconium and niobium. The alloy microstructure both influences the final oxidation products and is reflected in the microstructure of the oxide. The oxide scale itself has a predominantly columnar microstructure which extends from the oxide/metal interface to the outer surface of the oxide. In situ x-ray diffraction measurements revealed that the oxide scale is stressed in compression following cooling and exhibits strong crystallographic texture. The oxide/metal interface is continuous, without pores or voids which might be detrimental to oxide adhesion. In addition, we have identified a phase which develops at the interface between the beta-zirconium grains and the oxide. We have also identified amorphous regions within the oxide scale which serve as sinks for silicon and other impurity elements found in the alloy.

Alarin stimulates food intake and gonadotrophin release in male rats

BACKGROUND AND PURPOSE

Alarin is a recently discovered member of the galanin peptide family encoded by a splice variant of galanin-like peptide (GALP) mRNA. Galanin and GALP regulate energy homeostasis and reproduction. We therefore investigated the effects of alarin on food intake and gonadotrophin release.

EXPERIMENTAL APPROACH

Alarin was administered into the third cerebral ventricle (i.c.v.) of rats, and food intake or circulating hormone levels were measured. The effect of alarin on the hypothalamo-pituitary-gonadal axis was investigated in vitro using hypothalamic and anterior pituitary explants, and immortalized cell lines. Receptor binding assays were used to determine whether alarin binds to galanin receptors.

KEY RESULTS

The i.c.v. administration of alarin (30 nmol) to ad libitum fed male rats significantly increased acute food intake to 500%, and plasma luteinizing hormone (LH) levels to 170% of responses to saline. In vitro, 100 nM alarin stimulated neuropeptide Y (NPY) and gonadotrophin-releasing hormone (GnRH) release from hypothalamic explants from male rats, and 1000 nM alarin increased GnRH release from GT1-7 cells. In vivo, pretreatment with the GnRH receptor antagonist cetrorelix prevented the increase in plasma LH levels observed following i.c.v. alarin administration. Receptor binding studies confirmed alarin did not bind to any known galanin receptor, or compete with radiolabelled galanin for hypothalamic binding sites.

CONCLUSIONS AND IMPLICATIONS

These results suggest alarin is a novel orexigenic peptide, and that it increases circulating LH levels via hypothalamic GnRH. Further work is required to identify the receptor(s) mediating the biological effects of alarin.

A radial mode ultrasonic horn for the inactivation of Escherichia coli K12

Tuned cylindrical radial mode ultrasonic horns offer advantages over ultrasonic probes in the design of flow-through devices for bacterial inactivation. This study presents a comparison of the effectiveness of a radial horn and probe in the inactivation of Escherichia coli K12. The radial horn is designed using finite element analysis and the predicted modal parameters are validated using experimental modal analysis. A validated finite element model of the probe is also presented. Visual studies of the cavitation fields produced by the radial horn and probe are carried out using luminol and also backlighting to demonstrate the advantages of radial horns in producing a more focused cavitation field with widely dispersed streamers. Microbiological studies show that, for the same power density, better inactivation of E. coli K12 is achieved using the radial horn and, also, the radial horn offers greater achievable power density resulting in further improvements in bacterial inactivation. The radial horn is shown to be more effective than the probe device and offers opportunities to design in-line flow-through devices for processing applications.

The DNA sequence and biological annotation of human chromosome 1

The reference sequence for each human chromosome provides the framework for understanding genome function, variation and evolution. Here we report the finished sequence and biological annotation of human chromosome 1. Chromosome 1 is gene-dense, with 3,141 genes and 991 pseudogenes, and many coding sequences overlap. Rearrangements and mutations of chromosome 1 are prevalent in cancer and many other diseases. Patterns of sequence variation reveal signals of recent selection in specific genes that may contribute to human fitness, and also in regions where no function is evident. Fine-scale recombination occurs in hotspots of varying intensity along the sequence, and is enriched near genes. These and other studies of human biology and disease encoded within chromosome 1 are made possible with the highly accurate annotated sequence, as part of the completed set of chromosome sequences that comprise the reference human genome.

Determinants of musculoskeletal frailty and the risk of falls in old age

Neuromuscular parameters that describe locomotion are indispensable variables for the diagnosis and treatment of frailty, fall risk and osteoporosis. A scientifically-based standardized locomotor assessment should be an essential part of medical examinations in research and clinical practice. There has been no previous consensus regarding which test procedures should be included in a locomotor assessment. The goal of this article is to provide a rationale for the selection of appropriate locomotor tests in a comprehensive locomotor assessment for elderly patients. We propose that a locomotor assessment should comprise the parameters that have been proven predictive for both falls and impending disability. The parameters should be measured in the standard units of physics. Therefore, we propose the following tests for a standardized locomotor assessment: (1) Self-selected gait velocity as the single best measure of general locomotor status and a good predictor of age-related adverse events; (2) Chair rise test (timed 5 chair rises) which measures power on vertical movement and the hip surrounding muscles as the most important neuromuscular risk factor for falls and fall-related fractures; (3) Tandem standing and tandem walking to measure postural capacity (balance) to the side; (4) Timed up and go test as a global screening procedure; (5) Clinical gait analysis with special focus on regularity; and (6) At least on a research level, movement must be measured referring to the terms of physics by mechanography. Mechanography (Leonardo force plate system, Novotec Pforzheim, Germany) records the time course of ground reaction forces, velocity of the vertical movements of the center of mass and power during unrestricted physiological movements. In the mechanogram the eccentric and concentric phases of movements can be differentiated and the storage of energy in the elastic elements of the body can be examined. The kinetics of human movement is explained by mechanograms of a two-legged jump. The ground reaction forces resulting from a jump down from a height of 0,46 m are demonstrated as a performance that is representative for human coordination. One goal of this text is to underline the insights that arise if the rules of physics are applied to human movement. A deeper understanding enables us to create more effective treatments for disorders of the muscle-bone unit. Bringing physics and cybernetics into the field of osteoporosis is a great heritage of Harold Frost.

Non spiral and spiral (helical) flow patterns in stenoses. In vitro observations using spin and gradient echo magnetic resonance imaging (MRI) and computational fluid dynamic modeling

AIM

Physiological blood flow patterns are themselves poorly understood despite their impact on arterial disease. Stable spiral (helical) laminar flow (SLF) has been observed in normal subjects. The purpose of the present study is to develop a method of magnetic resonance (MR) flow pattern visualization and to analyze spiral and non-spiral flow patterns with and without luminal narrowing in vitro. The flow conditions were then modeled using computational fluid dynamics (Star-CD).

METHODS

Laminar integrity was examined in a flow-rig using spin and gradient echo magnetic resonance imaging (MRI) in non-stenosed and stenosed conduits in the presence of non-spiral and spiral flow.

RESULTS

No difference was observed in a non-stenosed conduit between non-spiral and spiral flow. In the presence of a stenosis spiral flow preserves flow velocity coherence whereas non-spiral flow increasingly lost coherence beginning proximal to the stenosis. Computational fluid dynamic modeling of the in vitro experiment showed marked differences between the 2 flow patterns. Non-spiral flow produced greater inwardly directed forces just beyond the stenosis and greater outward pressures at more distal sites. The near wall turbulent energy was up to 700% less with spiral flow over non-spiral flow beyond the stenosis.

CONCLUSIONS

Spiral flow appears to offer clear flow profile stabilizing advantages over non-spiral flow, by significantly reducing the turbulence caused by a stenosis. Spiral flow also produces lower forces acting on the vessel wall.

Results of the European Commission Marina II study: part II--effects of discharges of naturally occurring radioactive material

Enhanced levels of naturally occurring radioactive materials (NORM) are produced through various industrial operations and may lead to discharges to the marine environment. A recent study, called MARINA II, carried out for the European Commission considered discharges of radionuclides from the NORM industries to north European marine waters and their consequences. There are two main sources that were considered in the study. The use of phosphogypsum during the production of phosphoric acid by the fertiliser industry and the pumping of oil and gas from the continental shelf in the North Sea which produces large quantities of water contaminated with enhanced levels of naturally occurring radionuclides. Discharges of alpha emitting radionuclides from these two industries have contributed significantly to the total input of alpha emitters to north European waters over the period 1981-2000 (data were not available prior to 1981). Discharges due to the use of phosphogypsum have declined since the early 1990s and are now very low. Discharges from the oil and gas industries stabilised in the second half of the 1990s and are now the major contributor to alpha discharges to the region. As most European countries do not report discharges of radioactivity with the water produced during extraction, there is considerable uncertainty in the discharges used in the study. The impact of the discharges has been estimated both in terms of the effect on non-human biota and the radiological impact for people. In the 1980s the radiation dose rates to marine biota in the region around a phosphate plant on the north-west coast of England were as high due to the discharges from the phosphate plant as those near to the Sellafield reprocessing plant due to its discharges. In recent years the additional dose to marine biota in this region due to the past NORM discharges is of the same order of magnitude as the natural background. The collective dose rate was estimated to determine the radiological impact on people. The peak collective dose rate from the NORM industries occurred in 1984 and was just over 600 manSv y(-1). The collective dose rate fell with time as discharges from the phosphate industry reduced and was estimated as under 200 manSv y(-1) in 2000.