Right coronary artery flow velocity and volume assessment with spiral K-space sampled breathhold velocity-encoded MRI at 3 tesla: accuracy and reproducibility.

PURPOSE: To evaluate accuracy and reproducibility of flow velocity and volume measurements in a phantom and in human coronary arteries using breathhold velocity-encoded (VE) MRI with spiral k-space sampling at 3 Tesla. MATERIALS AND METHODS: Flow velocity assessment was performed using VE MRI with spiral k-space sampling. Accuracy of VE MRI was tested in vitro at five constant flow rates. Reproducibility was investigated in 19 healthy subjects (mean age 25.4 +/- 1.2 years, 11 men) by repeated acquisition in the right coronary artery (RCA). RESULTS: MRI-measured flow rates correlated strongly with volumetric collection (Pearson correlation r = 0.99; P < 0.01). Due to limited sample resolution, VE MRI overestimated the flow rate by 47% on average when nonconstricted region-of-interest segmentation was used. Using constricted region-of-interest segmentation with lumen size equal to ground-truth luminal size, less than 13% error in flow rate was found. In vivo RCA flow velocity assessment was successful in 82% of the applied studies. High interscan, intra- and inter-observer agreement was found for almost all indices describing coronary flow velocity. Reproducibility for repeated acquisitions varied by less than 16% for peak velocity values and by less than 24% for flow volumes. CONCLUSION: 3T breathhold VE MRI with spiral k-space sampling enables accurate and reproducible assessment of RCA flow velocity.

Distribution of hospital admissions in a middle-income country of the African region

Introduction: Few studies have reported the distribution of all hospital admissions at the entire country level in low and middle-income countries (LMICs). We examined this question in Seychelles, a rapidly developing small island state in the Africa region, in which access to health care is provided free of charge to all inhabitants through a national health system and all hospital admissions are routinely registered. Methods: Based on all admissions to all hospitals in Seychelles in 2005-2008, we calculated the distribution of hospital admissions, age at admission, length of stay and bed occupancy (i.e. cumulated number of patients * number of days spent in all hospitals) according to both hospital departments and broad causes of diseases (using codes of the ICD-10 classification of diseases). Results: Bed occupancy was largest in the surgical wards (36.7% of all days spent in all hospitals), followed by the medical wards (24.3%), gynecology/obstetrics wards (18.4%), pediatric wards (11.2%), and psychiatric wards (7.2%). According to broad causes of diseases/conditions, bed occupancy was highest for obstetrics/gynecology conditions (19.9% of all days spent at hospital), mental diseases (8.6%), cardiovascular diseases (8.1%), upper aerodigestive/pulmonary diseases (8%), infectious/parasitic diseases (8%), gastrointestinal diseases (7.2%), and urogenital diseases (6.7%). Adjusted to 100'000 population, 153 hospital beds are needed every day, including 31 for obstetrics/gynecologic conditions, 13 for mental diseases, 12 for cardiovascular diseases, 12 for upper aerodigestive diseases, 12 for infectious/parasitic diseases, and 11 for gastrointestinal diseases. Conclusion: Our findings give a good indication of the overall distribution of admissions according to both hospital departments and broad causes of diseases in a middle-income country. These findings provide important information for health care planning at the national level

Lessons learned from developing a national NCD programme in low- and middle-income countries (Seychelles)

This paper identifies selected issues and lessons learned from the implementation of a national program of prevention and control of non-communicable diseases (NCD) during the past 20 years in the Seychelles, a small island state in the African region. As early as in 1989, population-based surveys demonstrated high levels of several cardiovascular risk factors, which prompted an organized response by the government. The early creation of a NCD unit within the Ministry of Health, coupled with cooperation with international partners, enabled incremental capacity building and coherent development of NCD programs and policy. Information campaigns and screening for hypertension and diabetes in work/public places raised awareness and rallied increasingly broad awareness and support to NCD prevention and control. A variety of interventions were organized for tobacco control and comprehensive tobacco control legislation was enacted in 2009 (including total bans on tobacco advertising and on smoking in all enclosed public and work places). A recent School Nutrition Policy prohibits the sale of soft drinks in schools. At primary health care level, guidelines were developed for the management of hypertension and diabetes (these conditions are managed in all health centers within a national health system); regular interactive education sessions were organized for groups of high risk patients ("heart health club"); and specialized "NCD nurses" were trained. Decreasing prevalence of smoking is evidence of success, but the raising "diabesity epidemic" calls for strengthened health care to high-risk patients and broader multisectoral policy to mould an environment conducive to healthy behaviors. Key components of NCD prevention and control in Seychelles include effective surveillance mechanisms supplemented by focused research; generating broad interest and consensus on the need for prevention and control of NCD; mobilizing leadership and commitment at all levels; involving local and international expertise; building on existing efforts; and seeking integrated, multi-disciplinary and multisectoral approaches.

Respiratory effects of an exposure to grain dust among grain workers in the Vaud region (Switzerland)

Introduction: Bioaerosols such as grain dust (GD) elicit direct immunological reactions within the human respiratory system. Workplace-dependent exposure to GD may induce asthma, chronic bronchitis, and hypersensitivity pneumonitis. Aims: To assess the clinical impact of occupational exposure to GD and to determine quantitative biological markers of bioaerosol exposure in grain workers. Methods: This longitudinal study has been conducted from summer 2012 to summer 2013, comprising 6 groups of 30 active workers with different GD exposure patterns (4 groups of grain workers, 2 control groups). Two evaluations at high- and low-exposing seasons take place, during which an occupational and a medical history are questionnaire-assessed, lung function is evaluated by spirometry, airway inflammation is measured by exhaled nitric oxide (eNO) and specific blood IgG and IgE are titrated. Results: The preliminary results are those of 2 of the 4 exposed groups, (harvesters and mill workers), compared to the control groups, at first assessment (n=100). Mean age is 38.4 [years]; 98% are male. Exposed groups differ from controls (p<0.05) in daily contact with animals (57% vs. 40%) and active smoking (39% vs. 11%). Grain workers have more respiratory (50%), nasal (57%), ocular (45%) and dermatologic (36%) occupational symptoms than controls (6.4%, 19%, 16%, 6.4% respectively, p<0.05). Lower mean peak-expiratory-flow (PEF) values (96.1 ± 18.9 vs. 108.2 ± 17.4 [% of predicted], p<0.05) and eNO values (13.9 ± 9.6 vs. 20.5 ± 14.7 [ppm], p<0.05) are observed in the exposed groups. Conclusion: Preliminary results show a higher prevalence of clinical symptoms and a lower mean PEF value in the groups exposed to GD.

OVERLAND FLOW AND SURFACE RUNOFF / Hydrological Science and Engineering

Cape Verde, off the coast of Senegal in western Africa, is a volcanic archipelago where soil and water conservation techniques play an important role in the overall subsistence of half a million inhabitants. In fact, the step slopes in the more agricultural islands due to it's volcanic origin, together with semi-arid and arid environments (the country is located in the Sahelian region), characterized by a very irregular wet season, with high intensity rainfall events, make life tough. The hard conditions lead during the first half of the XX century to frequent cycles of drought with severe implications on the local populations, with impressive numbers of deaths by famine, and a decrease of the number of local inhabitants by more than halve in some islands. Maintain the soil in place and the water inside the soil was there after a mater of survival, and the CapeVerdians implemented over the last half century a number of soil and water conservation techniques that cover all the landscape. In this work, we monitored a number of slope soil and water conservation techniques, such as terraces, half moons, live barriers, etc, together with two cultural strategies, used to plant corn and beans on one side and peanuts on the other, with a semi-quantitative methodology, to evaluate their effectiveness. A discussion is given on the costs and effectiveness of the techniques to reduce overland flow production and therefore erosion, and to promote rainfall infiltration.

Optimization of multiclass queueing networks with changeover times via the achievable region approach: Part I, the single-station case

We address the performance optimization problem in a single-stationmulticlass queueing network with changeover times by means of theachievable region approach. This approach seeks to obtainperformance bounds and scheduling policies from the solution of amathematical program over a relaxation of the system's performanceregion. Relaxed formulations (including linear, convex, nonconvexand positive semidefinite constraints) of this region are developedby formulating equilibrium relations satisfied by the system, withthe help of Palm calculus. Our contributions include: (1) newconstraints formulating equilibrium relations on server dynamics;(2) a flow conservation interpretation of the constraintspreviously derived by the potential function method; (3) newpositive semidefinite constraints; (4) new work decomposition lawsfor single-station multiclass queueing networks, which yield newconvex constraints; (5) a unified buffer occupancy method ofperformance analysis obtained from the constraints; (6) heuristicscheduling policies from the solution of the relaxations.

Immunohistochemical and flow cytometric analysis of long-term label-retaining cells in the adult heart.

Cardiac-resident stem/progenitor cells have been identified based on expression of stem cell-associated antigens. However, no single surface marker allows to identify a definite cardiac stem/progenitor cell entity. Hence, functional stem cell markers have been extensively searched for. In homeostatic systems, stem cells divide infrequently and therefore retain DNA labels such as 5-bromo-2'-deoxyuridine, which are diluted with division. We used this method to analyze long-term label-retaining cells in the mouse heart after 14 days of 5-bromo-2'-deoxyuridine administration. Labeled cells were detected using immunohistochemical and flow-cytometric methods after varying chasing periods up to 12 months. Using mathematical models, the observed label dilution could consistently be described in the context of a 2-population model, whereby a population of rapidly dividing cells accounted for an accelerated early decline, and a population of slowly dividing cells accounted for decelerated dilution on longer time scales. Label-retaining cells were preferentially localized in the atria and apical region and stained negative for markers of the major cell lineages present in the heart. Most cells with long-term label-retention expressed stem cell antigen-1 (Sca-1). Sca-1(+)CD31(-) cells formed cell aggregates in culture, out of which lineage-negative (Lin(-))Sca-1(+)CD31(-) cells emerged, which could be cultured for many passages. These cells formed cardiospheres and showed differentiation potential into mesenchymal cell lineages. When cultured in cardiomyogenic differentiation medium, they expressed cardiac-specific genes. In conclusion, recognition of slow-cycling cells provides functional evidence of stem/progenitor cells in the heart. Lin(-)Sca-1(+)CD31(-) cardiac-derived progenitors have a potential for differentiation into cardiomyogenic and mesenchymal cell lineages.

Respiratory effects of an exposure to grain dust among grain workers in the Vaud region (Switzerland)

Introduction: Bioaerosols such as grain dust, via biologically active agents, elicit local inflammation and direct immunological reactions within the human respiratory system. Workplace-dependent exposure to grain dust (GD) may thus induce asthma, chronic bronchitis, and hypersensitivity pneumonitis. The aim of this study is to assess the clinical impact of occupational exposure to GD and to determine quantitative biological markers of bioaerosol exposure in grain workers. Methods: This longitudinal study has been conducted from summer 2012, to summer 2013, comprising 6 groups of 30 active workers with different GD exposure patterns (4 groups of grain workers, 2 control groups). After obtaining informed consent, two evaluations at high- and low-exposing seasons take place, during which an occupational history and a detailed medical history are questionnaire-assessed, lung function is evaluated by spirometry, airway inflammation is measured by exhaled nitric oxide (eNO), and specific blood IgG and IgE are titrated. The preliminary results presented hereafter are those of two of the four exposed groups, namely harvesters and mill workers, compared to the control groups, at first assessment (n=100). Results: Mean age is 38.4 [years]; 98% are male. Exposed groups differ from controls (p<0.05) in daily contact with animals (57% vs. 40%) and active smoking (39% vs. 11%). Grain workers have more respiratory (50%), nasal (57%), ocular (45%), dermatologic (36%) and systemic (20%) occupational symptoms than controls (6.4%, 19%, 16%, 6.4%, 1.6% respectively, p<0.05). Lower mean peak-expiratory-flow (PEF) values (96.1 ± 18.9 vs. 108.2 ± 17.4 [% of predicted], p<0.05) and eNO values (13.9 ± 9.6 vs. 20.5 ± 14.7 [ppm], p<0.05) are observed in the exposed groups. Conclusion: Preliminary results show a higher prevalence of clinical symptoms and a lower mean PEF value in the exposed groups. Detailed supplementary analyses are pending.

Glomerular hyperfiltration and increased proximal sodium reabsorption in subjects with type 2 diabetes or impaired fasting glucose in a population of the African region.

BACKGROUND. Glomerular hyperfiltration (GHF) is a well-recognized early renal alteration in diabetic patients. As the prevalence of GHF is largely unknown in populations in the African region with respect to normal fasting glucose (NFG), impaired fasting glucose (IFG) and type 2 diabetes [diabetes mellitus (DM)], we conducted a cross-sectional study in the Seychelles islands among families including at least one member with hypertension. METHODS. The glomerular filtration rate (GFR), effective renal plasma flow (ERPF) and proximal tubular sodium reabsorption were measured using inulin, p-aminohippurate (PAH) and endogenous lithium clearance, respectively. Twenty-four-hour urine was collected on the preceding day. RESULTS. Of the 363 participants (mean age 44.7 years), 6.6% had IFG, 9.9% had DM and 63.3% had hypertension. The prevalence of GHF, defined as a GFR >140 ml/min, was 17.2%, 29.2% and 52.8% in NFG, IFG and DM, respectively (P trend <0.001). Compared to NFG, the adjusted odds ratio for GHF was 1.99 [95% confidence interval (CI) 0.73-5.44] for IFG and 5.88 (2.39-14.45) for DM. Lithium clearance and fractional excretion of lithium were lower in DM and IFG than NFG (P < 0.001). CONCLUSION. In this population of African descent, subjects with impaired fasting glucose or type 2 diabetes had a high prevalence of GHF and enhanced proximal sodium reabsorption. These findings provide further insight on the elevated incidence of nephropathy reported among African diabetic individuals.

Risk factors of stroke mortality in the African region: a cohort study

Background: Population-based cohort studies of risk factors of stroke are scarce in developing countries and none has been done in the African region. We conducted a longitudinal study in the Seychelles (Indian Ocean, east of Kenya), a middle-income island state where the majority of the population is of African descent. Such data in Africa are important for international comparison and for advocacy in the region. Methods: Three examination surveys of cardiovascular risk factors were performed in independent samples representative of the general population aged 25-64 in 1989, 1994 and 2004 (n=1081, 1067, and 1255, respectively). Baseline risk factors data were linked with cause-specific mortality from vital statistics up to May 2007 (all deaths are medically certified in the Seychelles and kept in an electronic database). We considered stroke (any type) as a cause of death if the diagnosis was reported in any of the 4 fields in the death certificates for underlying and concomitant causes of death. Results. Among the 2479 persons aged 35-64 at baseline, 280 died including 56 with stroke during follow up (maximum: 18.2 years; mean: 10.2 years). In this age range, age-adjusted mortality rates (/100'000/year) were 969 for all cause and 187 for stroke; age-adjusted prevalence of high blood pressure (≥140/90 mmHg) was 48%. In multivariate Cox survival time regression, stroke mortality was increased by 18% and 35% for a 10-mmHg increase in systolic, respectively diastolic BP (p<0.001). Stroke mortality was also associated with age, smoking ≥5 cigarettes vs. no smoking (HR: 2.4; 95% CI: 1.2-4.8) and diabetes (HR: 1.9; 1.02-3.6) but not with sex, LDL-cholesterol intake, alcohol intake and professional occupation. Conclusion. This first population-based cohort study in the African region demonstrates high mortality rates from stroke in middle-aged adults and confirms associations with high BP and other risk factors. This emphasizes the importance of reducing BP and other modifiable risk factors in high risk individuals and in the general population as a main strategy to reduce the burden of stroke.

Nutrient supply by mass flow and diffusion to maize plants in response to soil aggregate size and water potential

Nutrients are basically transported to the roots by mass flow and diffusion. The aim of this study was to quantify the contribution of these two mechanisms to the acquisition of macronutrients (N, P, K, Ca, Mg, and S) and cationic micronutrients (Fe, Mn, Zn, and Cu) by maize plants as well as xylem exudate volume and composition in response to soil aggregate size and water availability. The experiment was conducted in a greenhouse with samples of an Oxisol, from under two management systems: a region of natural savanna-like vegetation (Cerradão, CER) and continuous maize under conventional management for over 30 years (CCM). The treatments were arranged in a factorial [2 x (1 + 2) x 2] design, with two management systems (CER and CCM), (1 + 2) soil sifted through a 4 mm sieve and two aggregate classes (< 0.5 mm and 0.5 - 4.0 mm) and two soil matric potentials (-40 and -10 kPa). These were evaluated in a randomized block design with four replications. The experiment was conducted for 70 days after sowing. The influence of soil aggregate size and water potential on the nutrient transport mechanisms was highest in soil samples with higher nutrient concentrations in solution, in the CER system; diffusion became more relevant when water availability was higher and in aggregates < 0.5 mm. The volume of xylem exudate collected from maize plants increased with the decrease in aggregate size and the increased availability of soil water in the CER system. The highest Ca and Mg concentrations in the xylem exudate of plants grown on samples from the CER system were related to the high concentrations of these nutrients in the soil solution of this management system.

Is the Gibraltar strait a barrier to gene flow for the bat Myotis myotis (Chiroptera: Vespertilionidae)?

Because of their role in limiting gene flow, geographical barriers like mountains or seas often coincide with intraspecific genetic discontinuities. Although the Strait of Gibraltar represents such a potential barrier for both plants and animals, few studies have been conducted on its impact on gene flow. Here we test this effect on a bat species (Myotis myotis) which is apparently distributed on both sides of the strait. Six colonies of 20 Myotis myotis each were sampled in southern Spain and northern Morocco along a linear transect of 1350 km. Results based on six nuclear microsatellite loci reveal no significant population structure within regions, but a complete isolation between bats sampled on each side of the strait. Variability at 600 bp of a mitochondrial gene (cytochrome b) confirms the existence of two genetically distinct and perfectly segregating clades, which diverged several million years ago. Despite the narrowness of the Gibraltar Strait (14 km), these molecular data suggest that neither males, nor females from either region have ever reproduced on the opposite side of the strait. Comparisons of molecular divergence with bats from a closely related species (M. blythii) suggest that the North African clade is possibly a distinct taxon warranting full species rank. We provisionally refer to it as Myotis cf punicus Felten 1977, but a definitive systematic understanding of the whole Mouse-eared bat species complex awaits further genetic sampling, especially in the Eastern Mediterranean areas.

Sex-linked genetic markers in the shrews of the Sorex araneus group : from free gene flow to speciation

SUMMARY: The shrews of the Sorex araneus group are morphologically .very similar, but have undergone a spectacular chromosomal evolution. Altogether, the shrews of this group present a complete array of every possible level of chromosomal and genetic differentiation. In South-Western Europe, four species are recognised: S. antiriorii, S. araneus, S. coronatus and S. granarius, which differ essentially by the amount and the composition of Robertsonian metacentric chromosomés. Additionally, several chromosome races of S. araneus are also present in the same region (i.e. Bretolet, Carlit, Cordon, Jura and Vaud). The objective of this thesis was to examine the genetic relationships between populations, races and /or species of the Sorex araneus group with a special emphasis onsex-specific markers (mtDNA and Y chromosome). We first investigate the evolutionary history of the shrews of the Sorex araneus group distributed in the South-Western Europe. The results of. these analyses confirmed the difficulty to draw a single dichotomic tree within this group. Incongruent mtDNA and Y chromosome phylogenies suggest further that genetic and chromosomal evolution are in this group partially independent processes and that the evolutionary history of the south-western European populations of the S. araneus group can only be understood if we consider secondary contacts between taxa, after their divergence (with genetic exchanges by means of hybridization and / or introgression). Using one male-inherited, one female inherited and eight biparentally inherited markers, we investigate the population genetic structure of the Valais shrew (Sorex antinorii). Overall there results suggest that two already well-differentiated genetic lineages colonized the Swiss Alps after the last glacial period and came into contact in the Rhône Valley. After the Valais shrew (Sorex antinorii) reached the Swiss Alps, it came into contact with the common shrew (Sorex araneus). When two species come into contact and hybridize, endogenous counter-selection of hybrids is usually first expressed as a reduced fertility or viability in hybrids of the heterogametic sex, a mechanism know as Haldane's rule (Haldane 1922). We first evaluated the extent of introgression for Y chromosome, mtDNA and autosomal markers in a hybrid zone between S. antinoriii and S. araneus. The overall level of genetic and karyotypic differentiation between the two species must be strong .enough to allow the detection asymmetric introgression. Secondly, we compared the levels of gene flow between chromosome common to both species and chromosome differently rearranged in each of them. We detected a significantly stronger genetic structure in rearranged chromosomes. Over a 10-year period, we even observed a decrease of genetic structure for common chromosomes. These results strongly support the role of chromosomal rearrangements in the reproductive barrier between S. araneus and S. anfinorii. Overall, this thesis underlines the need to use different inherited (paternally, maternally and / or biparentally) and chromosomally located (on common vs. on rearranged chromosomes) markers to obtain more accurate pictures of genetic relationships between populations or species. RÉSUMÉ: Les musaraignes du groupe Sorex araneus sont morphologiquement très proches, mais ont connu une spectaculaire évolution chromosomique. Prises dans leur ensemble, les musaraignes de ce groupe présentent tous les nivaux possibles de différenciation génétique et chromosomique. Dans le sud-ouest de l'Europe, quatre espèces appartenant à ce groupe sont présentes : S. antinorii, S. araneus, S. coronatus et S. granarius. Celles-ci diffèrent essentiellement par leur caryotype dont la variabilité est principalement due à des fusions Robertsoniennes. De plus, plusieurs races chromosomiques appartenant à S. araneus sont aussi présentes dans la même région (i.e. les races Bretolet, Carlit, Cordon, Jura et Vaud). L'objectif de cette thèse était d'examiner les relations génétiques entre populations, races et/ou espèces du groupe S. araneus, en utilisant particulièrement des marqueurs liés aux sexes (ADN mitochondrial et Chromosome Y). Nous avons dans un premier temps retracé l'histoire évolutive des musaraignes de ce groupe dans le sud-ouest de l'Europe. Les résultats dé ces analyses confirment qu'il est difficile de tracer un simple arbre dichotomique au sein de ce groupe. Les arbres phylogénétiques obtenus sur l'ADN mitochondrial et le chromosome Y sont incongruents et suggèrent de plus que l'évolution génétique et chromosomique sont des processus indépendants. L'histoire évolutive -des populations de ce groupe ne peut. être comprise qu'en considérant des contacts secondaires entre taxa postérieure à leur divergence et induisant des échanges génétiques par hybridation et/ou introgression. Par la suite, nous avons examiné la structure génétique des populations de la musaraigne du Valais, S. antinorii, en utilisant un marqueur transmis par les mâles, un marqueur transmis par les femelles et huit marqueurs transmis par les 2 sexes. Nos résultats suggèrent que deux lignées génétiquement bien différenciées aient colonisé les Alpes Suisses, après les dernières glaciations et entrent en contact dans là Vallée du Rhône. Après avoir franchi les Alpes Suisses, la musaraigne du Valais est entrée en contact avec là musaraigne commune (S. araneus). Lorsque deux espèces entrent en contact et s'hybrident, la sélection contre les hybrides implique habituellement une baisse de fertilité ou de viabilité des hybrides du sexe hétérogamétique (i.e. les mâles XY chez les mammifères). Ce mécanisme est connu sous le nom de règle de Haldane (Haldane 1922) et implique une plus forte structuration génétique de marqueurs males - spécifiques que des marqueurs femelles spécifiques. Nous avons donc évalué le degré d'introgression des marqueurs situés sur le chromosome Y, sur l'ADN mitochondrial et sur des autosomes dans une zone hybride entre S. araneus et S. antinorii. Le niveau de différenciation chromosomique et génétique entre les 2 espèces doit être suffisamment fort pour ne pas permettre la détection d'une introgression asymétrique entre les sexes. Dans un second temps, nous avons comparé les niveaux de flux de gênes mesurés à l'échelle du chromosome, pour des chromosomes communs aux deux espèces et pour des chromosomes différemment arrangées dans chacune des deux espèces. Nous avons détecté une structure génétique significativement plus forte sur les chromosomes réarrangés et comme la zone hybride a été étudiée à dix années d'intervalle, nous observons même une diminution de la structure génétique pour les chromosomes communs au cours du temps.. Ces résultats soutiennent fortement l'hypothèse d'un rôle des réarrangements chromosomiques dans l'établissement d'une barrière reproductive entre S. araneus et S. antinorii. Ainsi cette thèse souligne l'utilité d'utiliser des marqueurs génétiques avec différents modes de transmission. (par les mâles, par les femelles et/ou par les 2 sexes) ou localisés au niveau du chromosome (chromosomes communs vs chromosomes réarrangés) afin d'obtenir une image plus juste ou du moins plus complète des relations génétiques entre populations ou espèces.

Discordant secular trends in elevated blood pressure and obesity in children and adolescents in a rapidly developing country

BACKGROUND: The effect of the increasing prevalence of obesity on blood pressure (BP) secular trends is unclear. We analyzed BP and body mass index secular trends between 1998 and 2006 in children and adolescents of the Seychelles, a rapidly developing island state in the African region. METHODS AND RESULTS: School-based surveys were conducted annually between 1998 and 2006 among all students in 4 school grades (kindergarten and 4th, 7th, and 10th years of compulsory school). We used the Centers for Disease Control and Prevention criteria to define obesity and elevated BP. The same methods and instruments were used in all surveys. Some 25 586 children and adolescents 4 to 18 years of age contributed 43 867 observations. Although the prevalence of obesity in boys and girls increased from 5.1% and 6.0%, respectively, in 1998 to 2000 to 8.0% and 8.7% in 2004 to 2006, the prevalence of elevated BP decreased from 8.4% and 9.8% to 6.9% and 7.8%. During the interval, mean age-adjusted body mass index increased by 0.57 kg/m(2) in boys and 0.58 kg/m(2) in girls. Mean age- and height-adjusted systolic BP decreased by -3.0 mm Hg in boys and -2.8 mm Hg in girls, whereas mean diastolic BP did not change substantially in boys (-0.2 mm Hg) and increased slightly in girls (0.4 mm Hg). CONCLUSIONS: At a population level, the marked increase in the prevalence of obesity in children and adolescents in the Seychelles was not associated with a commensurate secular rise in mean BP.

Spatiotemporal adaptive multiscale multiphysics simulations of two-phase flow

We present a spatiotemporal adaptive multiscale algorithm, which is based on the Multiscale Finite Volume method. The algorithm offers a very efficient framework to deal with multiphysics problems and to couple regions with different spatial resolution. We employ the method to simulate two-phase flow through porous media. At the fine scale, we consider a pore-scale description of the flow based on the Volume Of Fluid method. In order to construct a global problem that describes the coarse-scale behavior, the equations are averaged numerically with respect to auxiliary control volumes, and a Darcy-like coarse-scale model is obtained. The space adaptivity is based on the idea that a fine-scale description is only required in the front region, whereas the resolution can be coarsened elsewhere. Temporal adaptivity relies on the fact that the fine-scale and the coarse-scale problems can be solved with different temporal resolution (longer time steps can be used at the coarse scale). By simulating drainage under unstable flow conditions, we show that the method is able to capture the coarse-scale behavior outside the front region and to reproduce complex fluid patterns in the front region.