Drag levels and energy requirements on a SCUBA diver

The popularity of sport diving has increased rapidly since its inception in the 1950’s. Over this period, the trend has been to increase the amount of equipment carried by the diver. There are many undoubted safety advantages associated with the additional kit, but under some conditions, it can impose an additional burden in the form of increased drag. The purpose of this paper is to identify the drag penalties for a number of simple SCUBA configurations. This is achieved through scale model experiments conducted in a wind tunnel. Some comments on the associated energy requirements are made, and from these, the effect on a diver’s bottom time is briefly addressed. The configurations tested include a study of the effect of the equipment configuration and the effect of small changes to the diver incidence. The tests show that the addition of a pony cylinder gives a 10% increase in drag compared to a conventional octopus set-up. When a dive knife, large torch and a Surface Marker Bouy (SMB) are also added this increases to 29%. Over the range tested, the average effect of swimming at a head up incidence to the flow is to increase the drag coefficient by 0.013/degree. This amounts to 16% at 5 degrees and 49% at 15 degrees. Estimates of the effect of the drag changes on bottom time show that particularly at the higher speeds the drag increases result in approximately similar percentage reductions in bottom time. Some simple suggestions for drag reduction are proposed

Perceptions of dental fluorosis in the Central Karoo District of the Western Cape Province

Masters of Public Health - see Magister Public HealthDental fluorosis is an endemic condition in a number of regions of South Africa, varying in degree of affliction according to the drinking water fluoride concentration in the area. Objective: While a number of South African studies have reported on the relationship between fluorosis and fluoride concentration in the drinking water, the purpose of this study was to determine perceptions of dental fluorosis in the Central Karoo District of the Western Cape. Methods: Learners aged 12-15 years and who had been lifelong residents in their respective areas were selected from schools in Leeu Gamka, Merweville, Nelspoort and Murraysburg. All the children meeting the inclusion criteria were included realising a total sample of 189. Drinking water fluoride concentration of each town was determined and concomitant fluorosis affliction was assessed. An interviewer administered questionnaire was used to determine respondents’ self-rated perceptions of fluorosis as well as their responses to a set of statements on clinically defined fluorosis. To this end four photographs, each depicting a different degree of fluorosis: (No fluorosis; Mild fluorosis; Moderate fluorosis; Severe fluorosis) were shown to the respondents. Results: In Leeu Gamka, with the highest fluoride concentration ([F] = 1.62ppm), 82% of respondents were aware of fluorosis stains as opposed to 6%-20% awareness in Merweville ([F] = 0.68), Nelspoort ([F] = 0.70) and Murraysburg ([F] = 0.56). Two thirds of respondents in Leeu Gamka found the appearance of their teeth embarrassing compared to only 2%-10% in the other 3 areas. The majority of respondents in Leeu Gamka (82%) indicated that they would want to remove the fluorosis spots with only 4%-20% in the lower fluoride areas. Two thirds (67%) of the Leeu Gamka respondents were teased compared to 2%-6% in the other areas. Most of the respondents have not tried to do anything to the appearance of the teeth, even in the higher fluoride area of Leeu Gamka. The average response varied little for all the photographs across the geographic areas (the minimum and maximum scores varied between 4.00 and 5.00) and reflected a greater tendency towards strongly disagreeing with the statement on aesthetics-even for the photographs depicting no fluorosis and mild fluorosis. The average response varied between 1 and 2 among all four geographic regions showing a tendency to “agree” and “strongly agree” to the statement on embarrassment. The average response to the statement on neglect varied little for all the photographs across the geographic areas as the minimum and maximum average response scores varied between 1.36 and 2.39 (agree and strongly agree). The response to the statement on disadvantage varied little for all the four photographs across the geographic areas (minimum=1.00, maximum=2.07) and reflected a greater tendency toward strongly agreeing and agreeing with the statement. Conclusion: The respondents from the higher fluoride area were more aware of dental fluorosis, had a greater perception of embarrassment and the strongest desire to remove the fluorosis staining. There was little variation in the average response to the statements on clinically defined fluorosis across the geographic areas. The learners erroneously believed that dental fluorosis was due to neglect, which is an indication that many learners are not aware of the cause of dental fluorosis in their community. The general consensus of the communities was that fluorosis was judged with feelings of negativity (embarrassment and a disadvantage for the child into adulthood)

Wachstumsminderung

X-ray absorption near edge structure (XANES) analysis in combination with synchrotron radiation induced total reflection X-ray fluorescence (SR-TXRF) acquisition was used to determine the oxidation state of Fe in human cancer cells and simultaneously their elemental composition by applying a simple sample preparation procedure consisting of pipetting the cell suspension onto the quartz reflectors. XANES spectra of several inorganic and organic iron compounds were recorded and compared to that of different cell lines. The XANES spectra of cells, independently from the phase of cell growth and cell type were very similar to that of ferritin, the main Fe store within the cell. The spectra obtained after CoCl2 or NiCl2 treatment, which could mimic a hypoxic state of cells, did not differ noticeably from that of the ferritin standard. After 5-fluorouracil administration, which could also induce an oxidative-stress in cells, the absorption edge position was shifted toward higher energies representing a higher oxidation state of Fe. Intense treatment with antimycin A, which inhibits electron transfer in the respiratory chain, resulted in minor changes in the spectrum, resembling rather the N-donor Fe-,′-dipyridyl complex at the oxidation energy of Fe(III), than ferritin. The incorporation of Co and Ni in the cells was followed by SR-TXRF measurements

Myocardial Tissue Remodeling in Adolescent Obesity

Background: Childhood obesity is a significant risk factor for cardiovascular disease in adulthood. Although ventricular remodeling has been reported in obese youth, early tissue‐level markers within the myocardium that precede organ‐level alterations have not been described. Methods and Results: We studied 21 obese adolescents (mean age, 17.7±2.6 years; mean body mass index [BMI], 41.9±9.5 kg/m2, including 11 patients with type 2 diabetes [T2D]) and 12 healthy volunteers (age, 15.1±4.5 years; BMI, 20.1±3.5 kg/m2) using biomarkers of cardiometabolic risk and cardiac magnetic resonance imaging (CMR) to phenotype cardiac structure, function, and interstitial matrix remodeling by standard techniques. Although left ventricular ejection fraction and left atrial volumes were similar in healthy volunteers and obese patients (and within normal body size‐adjusted limits), interstitial matrix expansion by CMR extracellular volume fraction (ECV) was significantly different between healthy volunteers (median, 0.264; interquartile range [IQR], 0.253 to 0.271), obese adolescents without T2D (median, 0.328; IQR, 0.278 to 0.345), and obese adolescents with T2D (median, 0.376; IQR, 0.336 to 0.407; P=0.0001). ECV was associated with BMI for the entire population (r=0.58, P<0.001) and with high‐sensitivity C‐reactive protein (r=0.47, P<0.05), serum triglycerides (r=0.51, P<0.05), and hemoglobin A1c (r=0.76, P<0.0001) in the obese stratum. Conclusions: Obese adolescents (particularly those with T2D) have subclinical alterations in myocardial tissue architecture associated with inflammation and insulin resistance. These alterations precede significant left ventricular hypertrophy or decreased cardiac function

Narrative review of Ebstein's anomaly beyond childhood: imaging, surgery, and future perspectives

Ebstein's anomaly is a rare congenital heart disease with malformation of the tricuspid valve and myopathy of the right ventricle. The septal and inferior leaflets adhere to the endocardium due to failure of delamination. This leads to apical displacement of their hinge points with a shift of the functional tricuspid valve annulus towards the right ventricular outflow tract with a possibly restrictive orifice. Frequently, a coaptation gap yields tricuspid valve regurgitation and over time the "atrialized" portion of the right ventricle may dilate. The highly variable anatomy determines the clinical presentation ranging from asymptomatic to very severe with need for early operation. Echocardiography and magnetic resonance imaging are the most important diagnostic modalities to assess the tricuspid valve as well as ventricular morphology and function. While medical management of asymptomatic patients can be effective for many years, surgical intervention is indicated before development of significant right ventricular dilatation or dysfunction. Onset of symptoms and arrhythmias are further indications for surgery. Modified cone reconstruction of the tricuspid valve is the state-of-the-art approach yielding the best results for most patients. Alternative procedures for select cases include tricuspid valve replacement and bidirectional cavopulmonary shunt depending on patient age and other individual characteristics. Long-term survival after surgery is favorable but rehospitalization and reoperation remain significant issues. Further studies are warranted to identify the optimal surgical strategy and timing before adverse right ventricular remodeling occurs. It is this article's objective to provide a comprehensive review of current literature and an overview on the management of Ebstein's Anomaly. It focuses on imaging, cardiac surgery, and outcome. Additionally, a brief insight into arrhythmias and their management is given. The "future perspectives" summarize open questions and fields of future research.Thoracic Surger

Ambient noise tomography reveals upper crustal structure of Icelandic rifts

The structure of oceanic spreading centres and subsurface melt distribution within newly formed crust is largely understood from marine seismic experiments. In Iceland, however, sub-aerial rift elevation allows both accurate surface mapping and the installation of large broadband seismic arrays. We present a study using ambient noise Rayleigh wave tomography to image the volcanic spreading centres across Iceland. Our high resolution model images a continuous band of low seismic velocities, parallelling all three segments of the branched rift in Iceland. The upper 10 km contains strong velocity variations, with shear wave velocities 0.5 km s$^{−1}$ faster in the older non-volcanically active regions compared to the active rifts. Slow velocities correlate very closely with geological surface mapping, with contours of the anomalies parallelling the edges of the neo-volcanic zones. The low-velocity band extends to the full 50 km width of the neo-volcanic zones, demonstrating a significant contrast with the narrow (8 km wide) magmatic zone seen at fast spreading ridges, where the rate of melt supply is similarly high. Within the seismically slow rift band, the lowest velocity cores of the anomalies occur above the centre of the mantle plume under the Vatnajökull icecap, and in the Eastern Volcanic Zone under the central volcano Katla. This suggests localisation of melt accumulation at these specific volcanic centres, demonstrating variability in melt supply into the shallow crust along the rift axis. Shear velocity inversions with depth show that the strongest velocity contrasts are found in the upper 8 km, and show a slight depression in the shear velocity through the mid crust (10–20 km) in the rifts. Our model also shows less intensity to the slow rift anomaly in the Western Volcanic Zone, supporting the notion that rift activity here is decreasing as the ridge jumps to the Eastern Volcanic Zone.Seismometers were borrowed from the Natural Environment Research Council (NERC) SEIS-UK (loans 968 and 1022). The work was funded by a graduate studentship from the NERC and research grants from the NERC (grants NE/F01140711, NE/M017427/1, NE/H025006/1) and the European Community's Seventh Framework Programme Grant No. 308377 (FUTUREVOLC) ... IMAGE project has received funding from the European Union's Seventh Programme for research, technological development and demonstration under grant agreement number 608553. Stations for this project were provided by the Geophysical Instrument Pool of Potsdam (GFZ). Dept. Earth Sciences, Cambridge contribution number ESC3818