Time scales of melt extraction revealed by distribution of lava composition across a ridge axis

International audienceTemporal fluctuations of magmatic processes during the last 800 kyr have been investigated for the slow spreading Central Indian Ridge. The fluctuations are recorded by variations in lava chemistry along a 40 km long profile across the ridge. The temporal relations of the basalts were accurately restored using magnetic microanomalies. We report on the occurrence of ancient lavas enriched in incompatible elements whereas on-axis samples are typical normal mid-ocean ridge basalts. The enriched lavas are symmetrically distributed on either side of the ridge, implying that enriched melts reached the seafloor at intervals of about 150–200 kyr. This periodicity is viewed as a characteristic time scale in the aggregation processes of the melts produced from a heterogeneous mantle source. Geochemical variations of zero-age mid-ocean ridge basalts may primarily reflect such periodic processes rather than the spatial distribution of mantle heterogeneities

Cell and matrix response of temporomandibular cartilage to mechanical loading

OBJECTIVES: The generation of transgenic mice expressing green fluorescent proteins (GFPs) has greatly aided our understanding of the development of connective tissues such as bone and cartilage. Perturbation of a biological system such as the temporomandibular joint (TMJ) within its adaptive remodeling capacity is particularly useful in analyzing cellular lineage progression. The objectives of this study were to determine: (i) if GFP reporters expressed in the TMJ indicate the different stages of cell maturation in fibrocartilage and (ii) how mechanical loading affects cellular response in different regions of the cartilage. DESIGN/METHODS: Four-week-old transgenic mice harboring combinations of fluorescent reporters (Dkk3-eGFP, Col1a1(3.6 kb)-GFPcyan, Col1a1(3.6 kb)-GFPtpz, Col2a1-GFPcyan, and Col10a1-RFPcherry) were used to analyze the expression pattern of transgenes in the mandibular condylar cartilage (MCC). To study the effect of TMJ loading, animals were subjected to forced mouth opening with custom springs exerting 50 g force for 1 h/day for 5 days. Dynamic mineralization and cellular proliferation (EdU-labeling) were assessed in loaded vs control mice. RESULTS: Dkk3 expression was seen in the superficial zone of the MCC, followed by Col1 in the cartilage zone, Col2 in the prehypertrophic zone, and Col10 in the hypertrophic zone at and below the tidemark. TMJ loading increased expression of the GFP reporters and EdU-labeling of cells in the cartilage, resulting in a thickness increase of all layers of the cartilage. In addition, mineral apposition increased resulting in Col10 expression by unmineralized cells above the tidemark. CONCLUSION: The TMJ responded to static loading by forming thicker cartilage through adaptive remodeling

Malaria Clusters among Illegal Chinese Immigrants to Europe through Africa

Between November 2002 and March 2003, 17 cases of malaria (1 fatal) were observed in illegal Chinese immigrants who traveled to Italy through Africa. A further cluster of 12 was reported in August, 2002. Several immigrants traveled by air, making the risk of introducing sudden acute respiratory syndrome a possibility should such illegal immigrations continue

Methylation of class II transactivator gene promoter IV is not associated with susceptibility to Multiple Sclerosis

<p>Abstract</p> <p>Background</p> <p>Multiple sclerosis (MS) is a complex trait in which alleles at or near the class II loci <it>HLA-DRB1 </it>and <it>HLA-DQB1 </it>contribute significantly to genetic risk. The MHC class II transactivator (<it>MHC2TA</it>) is the master controller of expression of class II genes, and methylation of the promoter of this gene has been previously been shown to alter its function. In this study we sought to assess whether or not methylation of the <it>MHC2TA </it>promoter pIV could contribute to MS disease aetiology.</p> <p>Methods</p> <p>In DNA from peripheral blood mononuclear cells from a sample of 50 monozygotic disease discordant MS twins the <it>MHC2TA </it>promoter IV was sequenced and analysed by methylation specific PCR.</p> <p>Results</p> <p>No methylation or sequence variation of the <it>MHC2TA </it>promoter pIV was found.</p> <p>Conclusion</p> <p>The results of this study cannot support the notion that methylation of the pIV promoter of <it>MHC2TA </it>contributes to MS disease risk, although tissue and timing specific epigenetic modifications cannot be ruled out.</p

Метод долгосрочного прогноза дрейфа льда в Арктическом бассейне

Based on the data of automatic “Argos” buoys, the frequency of occurrence of the monthly fields of ice drift velocity with presence of the anticyclonic eddy in them was calculated for the annual ice cycles. It was determined that at close values of the frequency of occurrence for different years, the drift velocity fields are also identical to each other in many aspects. On this basis the total number of years with initial data is divided into three groups by the value of the frequency of occurrence. The prognostic calculation of ice motion is performed by the monthly fields of the group the values of the frequency of occurrence of which will correspond to a greater extent to the frequency of occurrence of the current annual ice cycle. The article presents information on the basis of which the choice of the analogous group of years is presented. Technology of the prognostic ice motion calculation by the monthly drift velocity fields for the chosen analogous years is given. The results of determination of the skill score and efficiency of the method obtained taking into account the ellipse of permissible error are presented.По данным автоматических буев «Аргос» за годовые ледовые циклы рассчитана повторяемость месячных полей скорости дрейфа льда с наличием в каждом из них антициклонического вихревого образования. Установлено, что при близких значениях повторяемости за разные годы поля скорости дрейфа также во многом идентичны друг другу. На этом основании совокупность лет с исходными данными по величине повторяемости разделена на 3 группы. Прогностический расчет перемещения льда выполняется по месячным полям той из них, значения повторяемости которой будут, как ожидается, в большей мере соответствовать повторяемости текущего годового ледового цикла. Приведена информация, на основании которой осуществляется выбор аналоговой группы лет. Изложена технология прогностического расчета перемещения льда по месячным полям скорости дрейфа за выбранные аналоговые годы. Представлены результаты определения оправдываемости и эффективности метода, полученные с учетом эллипса допустимой погрешности

Пространственные различия плотности разрывов в ледяном покрове приатлантической части Арктического бассейна

We analyzed data on the spatial distribution (density) of large breaks (gaps) in the drifting sea ice cover in the Western Arctic for the period from October 2005 to September 2017, obtained through decoding of lowresolution images from the NOAA satellites. The specific length of gaps, which is the total length of them over an area of 1 km2, is used as a characteristic of the spatial density. It was found that along the continental slope, approximately from the meridian 70° E to the Lincoln Sea, there is a well-defined area of high density, which remains throughout most part of the ice cycle. In this area, the values of the specific gap length averaged over two-month periods exceeded 24 m/km2. In the near-polar region, the density of breaks was smaller throughout the whole ice cycle. The least values of the specific length take place in May–June that is caused by changes in the general state of the ice cover. It was determined that the density of gaps in this area of the Arctic basin well correlated with the speed of wind drift of ice: the more intensive the drift, the larger the density. On the continental slope, two local zones with maximum values of the specific length of breaks reaching 32 m/km2 are considered. It is suggested that the stability of their location in space and time is connected with the increased influence of tidal processes on the deformation of the ice cover over local bottom elevations on the continental slope. A correlation between the bottom profile and the values of the specific length of the gaps along two conditional lines passing through the maximum value zones did show that the largest values of the density are noticed in areas with significant gradients of the depth.На основе расчёта плотности разрывов в ледяном покрове приатлантической части Арктического бассейна по спутниковым данным за 2006–2017 гг. установлено, что на протяжении большей части ледового цикла в полях распределения удельной длины разрывов хорошо выражена обширная область её повышенных значений. Обосновано предположение, что причина возникновения локальных зон с повышенной плотностью разрывов – приливные явления. В открытой части Арктического бассейна значения удельной длины разрывов согласуются в основном со скоростью ветрового дрейфа льда

Transtheoretical Model-based multiple behavior intervention for weight management: Effectiveness on a population basis

Background: The increasing prevalence of overweight and obesity underscores the need for evidence-based, easily disseminable interventions for weight management that can be delivered on a population basis. The Transtheoretical Model (TTM) offers a promising theoretical framework for multiple behavior weight management interventions. Methods: Overweight or obese adults (BMI 25–39.9; n = 1277) were randomized to no-treatment control or home-based, stage-matched multiple behavior interventions for up to three behaviors related to weight management at 0, 3, 6, and 9 months. All participants were re-assessed at 6, 12, and 24 months. Results: Significant treatment effects were found for healthy eating (47.5% versus 34.3%), exercise (44.90% versus 38.10%), managing emotional distress (49.7% versus 30.30%), and untreated fruit and vegetable intake (48.5% versus 39.0%) progressing to Action/Maintenance at 24 months. The groups differed on weight lost at 24 months. Co-variation of behavior change occurred and was much more pronounced in the treatment group, where individuals progressing to Action/Maintenance for a single behavior were 2.5–5 times more likely to make progress on another behavior. The impact of the multiple behavior intervention was more than three times that of single behavior interventions. Conclusions: This study demonstrates the ability of TTM-based tailored feedback to improve healthy eating, exercise, managing emotional distress, and weight on a population basis. The treatment produced a high level of population impact that future multiple behavior interventions can seek to surpass

The Inheritance of Resistance Alleles in Multiple Sclerosis

Multiple sclerosis (MS) is a complex trait in which alleles at or near the class II loci HLA-DRB1 and HLA-DQB1 contribute significantly to genetic risk. HLA-DRB1*15 and HLA-DRB1*17-bearing haplotypes and interactions at the HLA-DRB1 locus increase risk of MS but it has taken large samples to identify resistance HLA-DRB1 alleles. In this investigation of 7,093 individuals from 1,432 MS families, we have assessed the validity, mode of inheritance, associated genotypes, and the interactions of HLA-DRB1 resistance alleles. HLA-DRB1*14-, HLA-DRB1*11-, HLA-DRB1*01-, and HLA-DRB1*10-bearing haplotypes are protective overall but they appear to operate by different mechanisms. The first type of resistance allele is characterised by HLA-DRB1*14 and HLA-DRB1*11. Each shows a multiplicative mode of inheritance indicating a broadly acting suppression of risk, but a different degree of protection. In contrast, a second type is exemplified by HLA-DRB1*10 and HLA-DRB1*01. These alleles are significantly protective when they interact specifically in trans with HLA-DRB1*15-bearing haplotypes. HLA-DRB1*01 and HLA-DRB1*10 do not interact with HLA-DRB1*17, implying that several mechanisms may be operative in major histocompatibility complex–associated MS susceptibility, perhaps analogous to the resistance alleles. There are major practical implications for risk and for the exploration of mechanisms in animal models. Restriction of antigen presentation by HLA-DRB1*15 seems an improbably simple mechanism of major histocompatibility complex–associated susceptibility

Active oceanic spreading in the northern north Fiji basin : results of the NOFI cruise of R/V l'Atalante (Newstarmer project)

The South Pandora and the Tripartite Ridges are active spreading centers located in the northern part of the North Fiji Basin. These spreading centers were surveyed over a distance of 750 km during the NOFI cruise of R/V L'Atalante (August-September 1994) which was conducted in the frame of the french-japanese Newstarmer cooperation project. SIMRAD EM12-dual full coverage swath bathymetric and imagery data as well as airgun 6-channel seismic, magnetics and gravity profiles were recorded along an off-axis from 170°40'E to 178°E. Dredging and piston coring were also performed along and off-axis. The axial domain of the South Pandora Ridge is divided into 5 first-order segments characterized by contrasted morphologies. The average width of the active domain is 20 km and corresponds either to bathymetric highs or to deep elongated grabens. The bathymetric highs are volcanic constructions, locally faulted and rifted, which can obstruct totally the axial valley. The grabens show the typical morphology of slow spreading axes, with two steep walls flanking a deep axial valley. Elongated lateral ridges may be present on both sides of the grabens. Numerous volcanoes, up to several kilometers in diameter, occur on both flanks of the South Pandora Ridge. The Tripartite Ridge consists of three main segments showing a sigmoid shape. Major changes in the direction of the active zones are observed at the segment discontinuities. These discontinuities show various geometrical patterns which suggest complex transform relay zones. Preliminary analysis of seismic reflection profiles suggest that the Tripartite Ridge is a very young feature which propagates into an older oceanic domain characterized by a significant sedimentary cover. By contrast, a very thin to absent sedimentary cover is observed about 100 km on both flanks of the South Pandora Ridge active axis. The magnetic anomaly profiles give evidence of long and continuous lineations, parallel to the South Pandora Ridge spreading axis. (Résumé d'auteur