A model for the biological precipitation of Precambrian iron-formation

A biological model for the precipitation of Precambrian iron formations is presented. Assuming an oxygen deficient atmosphere and water column to allow sufficient Fe solubility, it is proposed that local oxidizing environments, produced biologically, led to precipitation of iron formations. It is further suggested that spheroidal structures about 30 mm in diameter, which are widespread in low grade cherty rion formations, are relict forms of the organic walled microfossil Eosphaera tylerii. The presence of these structures suggests that the organism may have had a siliceous test, which allowed sufficient rigidity for accumulation and preservation. The model involves precipitation of ferric hydrates by oxidation of iron in the photic zone by a variety of photosynthetic organisms. Silica may have formed in the frustules of silica secreting organisms, including Eosphaera tylerii. Iron formates formed, therefore, by a sediment rain of biologically produced ferric hydrates and silica and other organic material. Siderite and hematite formed diagenetically on basin floors, and subsequent metamorphism produced magnetite and iron silicates

The Wisconsin magmatic terrane: An Early Proterozoic greenstone-granite terrane formed by plate tectonic processes

The Wisconsin magmatic terrane (WMT) is an east trending belt of dominantly volcanic-plutonic complexes of Early Proterozoic age (approx. 1850 m.y.) that lies to the south of the Archean rocks and Early Proterozoic epicratonic sequence (Marquette Range Supergroup) in Michigan. It is separated from the epicratonic Marquette Range Supergroup by the high-angle Niagara fault, is bounded on the south, in central Wisconsin, by Archean gneisses, is truncated on the west by rocks of the Midcontinent rift system, and is intruded on the east by the post-orogenic Wolf river batholith. The overall lithologic, geochemical, metallogenic, metamorphic, and deformational characteristics of the WMT are similar to those observed in recent volcanic arc terranes formed at sites of plate convergence. It is concluded that the WMT represents an evolved oceanic island-arc terrane accreated to the Superior craton in the Early Proterozoic. This conclusion is strengthened by the apparent absence of Archean basement from most of the WMT, and the recent recognition of the passive margin character of the epicratonic Marquette Range Supergroup

Static and dynamic pitching moment measurements on a family of elliptic cones at Mach number 11 in helium

Static and dynamic pitching moment measurements were made on a family of constant volume elliptic cones about two fixed axes of oscillation in the NAE helium hypersonic wind tunnel at a Mach number of 11 and at Reynolds numbers based on model length of up to 14 million. Viscous effects on the stability derivatives were investigated by varying the Reynolds number for certain models by a factor as large as 10. The models investigated comprised a 7.75 deg circular cone, elliptic cones of axis ratios 3 and 6, and an elliptic cone with conical protuberances

A comparison between legume technologies and fallow, and their effects on maize and soil traits, in two distinct environments of the West African savannah

Legume¿maize rotation and maize nitrogen (N)-response trials were carried out simultaneously from 1998 to 2004 in two distinct agro-ecological environments of West Africa: the humid derived savannah (Ibadan) and the drier northern Guinea savannah (Zaria). In the N-response trial, maize was grown annually receiving urea N at 0, 30, 60, 90 and 120 kg N ha¿1. In Ibadan, maize production increased with N fertilization, but mean annual grain yield declined over the course of the trial. In Zaria, no response to N treatments was observed initially, and an increase in the phosphorus (P) and sulphur (S) fertilizer application rate was required to increase yield across treatments and obtain a response to N applications, stressing the importance of non-N fertilizers in the savannah. In the rotation trial, a 2-year natural fallow¿maize rotation was compared with maize rotated with different legume types: green manure, forage, dual-purpose, and grain legumes. The cultivation of some legume types resulted in a greater annual maize production relative to the fallow¿maize combination and corresponding treatments in the N-response trial, while there was no gain in maize yield with other legume types. Large differences in the residual effects from legumes and fallow were also observed between sites, indicting a need for site-specific land management recommendations. In Ibadan, cultivation of maize after the forage legume (Stylosanthes guianensis) achieved the highest yield. The natural fallow¿maize rotation had improved soil characteristics (Bray-I P, exchangeable potassium, calcium and magnesium) at the end of the trial relative to legume¿maize rotations, and natural fallow resulted in higher maize yields than the green manure legume (Pueraria phaseoloides). In Zaria, maize following dual-purpose soybean achieved the highest mean yield. At both sites, variation in aboveground N and P dynamics of the legume and fallow vegetation could only partly explain the different residual effects on maiz

Analyses directionnelles multivariées de la qualité des précipitations sur la région de Québec

La question des précipitations acides est devenue une des principales préoccupations environnementales de ce siècle. Les dommages engendrés touchent l'ensemble des composantes atmosphérique, aquatique et terrestre de notre écosystème. Dans cet article, l'intérêt est tourné vers le transport des substances polluantes en faisant intervenir le vecteur des précipitations acides: le vent. Il existe une croyance populaire, largement répandue dans l'est du Canada, consistant à admettre que les vents d'est ou du nord sont associés à des précipitations faiblement chargées en éléments acides, contrairement aux vents du sud-ouest qui transporteraient les charges plus contaminées des industries situées dans le Midwest nord-américain. Une confirmation expérimentale de la réalité du phénomène est présentée ici.Une analyse factorielle des correspondances permet de mettre en évidence des relations entre la direction des vents et la composition chimique des précipitations. Des analyses de variance permettent ensuite de montrer la signification de l'effet de la direction des vents sur les concentrations de sulfates et de nitrates, en plus de mettre en évidence un effet saisonnier significatif pour ces deux variables. Les concentrations de nitrates et de sulfates associées aux vents de l'ouest sont respec- tivement de 0,33 mg/l-¹ et 1,73 mg/l-¹ comparativement à 0,24 mg/l-¹ et 1,48 mg/l-¹ pour les vents provenant de l'est. En ce qui concerne l'effet saisonnier, les concentrations moyennes de nitrates sont plus élevées durant les mois de janvier et de mars alors que les concentrations de sulfates sont plus elevées durant les mois d'été.The problem of acidic precipitation has become an important environmental concern; related damages can affect atmospheric, terrestrial and aquatic components of our ecosystem. This paper focuses on wind-driven atmospheric transport of contaminants, notably niirates and sulfates. Conventional wisdom in eastern Canada holds that winds originating from the east bring precipitation less loaded with acidic components than winds originating from the southwest; the latter carry contarninants generated by industries located in the American Midwest.An experimental confirmation of this phenomenon is presented here. SPERBER (1987) showed that hourly series of piecipitation content and wind direction, measured at a reception site are adequate to represent the lagrangian history of precipitating systems (New York City region). Following this result, we suppose that the northesastern continental atmospheric system is homogeneous enough so that winds measured at our reception site (Québec City region) are representative of the whole system. Thus, our experiment is performed in eulerian coordinates.The data bank used in the statistic alana|yses contains 10 time series: the weekly concentrations of 9 compounds found in the precipitation (H, Ca, Cl, K, Mg, Na, NO3, NH4 and SO4) gathered at the local Montmorency site and a s:ries ofweekly prevailing winds measured at the nearby Québec City airport. The time series contain 312 observations covering a full six year period (December 1981 to December 1987). As the original data bank of corcentrations is episodic, i.e. an obsercvation is available for each day with a significant precipitation event, volumes and loadings are used to derive the average weekly values of concentrations. In contrast, hourly series of direction (projected in 36 directions) and velocity of the prevailing winds are used to build, via a vectorial addition, a weekly series of wind direitions projected on a 12 point wind rose where directions corespond to the nind origin and not its destination.Classic statistical methods are used to deal with this data bank. Principal component analysis studies relationships between series of concentrations in the precipitations, while correspondence analysis highrights the relationships betwlen tile series of precipitation content and the series ofwind direction. The final statistical method, analysis of variance, is used to test the signilïcance of relationships higtrlighted by the correspondence analysis.The principal component analysis shows that all variables were positively correlated with the first component which reflects the fact that a higtrly loaded precipitation event will show high concentrations for each ofthe nine variables. The second component discriminates two groups of variables: one includes NO3, NH4 and SO4, the other Ca, Mg and Cl. The acidity variable, H, is nearer to the acid ion group (NO3, NH4 and SO4) than to the other ion group (Ca, Mg and Cl).The correspondence analysis shows that high concentrations of acidic compounds (NO3, NH4 and SO4) are highly rerated to winds from the W and WSW directions; conversely lower concentrations of the same compounds are associated with winds from the E and ENE directions. The elements Ca, Mg and Cl, reputed to be of oceanic origin, show high functional relationships between high concentrations and E, ENE winds and also between low concentrations and W, WSW winds. These results support the popular belief initially presented that acid precipitation is largely associated with winds from the southwest.The analyses of variance show that precipitation concentrations (NO3 and SO4) are significantly different according to the wind directions. Nitrate and sulfate concentrations associated with winds originating from the west are respectively 0.33-mg.l-l and 1.73 mg.l-l compared, to 0.24 mg.l-l and 1.48 mg.l-l for winds originating from the east. The analyses ofvariance also indicate a significant seasonal effect where mean monthly concentrations in nitrates are hilhest for winter months and early spring whereas sulfate concentrations are highest for the summer months

Renovation-Year Forage Quality of Grass Pastures Sod-Drilled With Kura Clover

Including legumes can enhance yield, quality, and animal performance potential of grass pastures. Kura clover is an exceptionally winter hardy forage legume with high forage quality (Taylor & Smith, 1998). However, its seedling vigor is poor. Herbicide sod suppression prior to sod drilling enabled kura clover to establish in the north central USA and eastern Canada (Cuomo et al., 2001; Laberge et al., 2005), but its percentage of renovation-year forage yield was less than for sod-seeded red or white clover. The objective of this study was to determine the influence of herbicide suppression and clover species on renovation-year forage quality of grass pastures sod-drilled with Kura clover versus red or white clover

Scheduling optimization of parallel linear algebra algorithms using Supervised Learning

Linear algebra algorithms are used widely in a variety of domains, e.g machine learning, numerical physics and video games graphics. For all these applications, loop-level parallelism is required to achieve high performance. However, finding the optimal way to schedule the workload between threads is a non-trivial problem because it depends on the structure of the algorithm being parallelized and the hardware the executable is run on. In the realm of Asynchronous Many Task runtime systems, a key aspect of the scheduling problem is predicting the proper chunk-size, where the chunk-size is defined as the number of iterations of a for-loop assigned to a thread as one task. In this paper, we study the applications of supervised learning models to predict the chunk-size which yields maximum performance on multiple parallel linear algebra operations using the HPX backend of Blaze's linear algebra library. More precisely, we generate our training and tests sets by measuring performance of the application with different chunk-sizes for multiple linear algebra operations; vector-addition, matrix-vector-multiplication, matrix-matrix addition and matrix-matrix-multiplication. We compare the use of logistic regression, neural networks and decision trees with a newly developed decision tree based model in order to predict the optimal value for chunk-size. Our results show that classical decision trees and our custom decision tree model are able to forecast a chunk-size which results in good performance for the linear algebra operations.Comment: Accepted at HPCML1

Planetary Gearbox Fault Detection Using Vibration Separation Techniques

Studies were performed to demonstrate the capability to detect planetary gear and bearing faults in helicopter main-rotor transmissions. The work supported the Operations Support and Sustainment (OSST) program with the U.S. Army Aviation Applied Technology Directorate (AATD) and Bell Helicopter Textron. Vibration data from the OH-58C planetary system were collected on a healthy transmission as well as with various seeded-fault components. Planetary fault detection algorithms were used with the collected data to evaluate fault detection effectiveness. Planet gear tooth cracks and spalls were detectable using the vibration separation techniques. Sun gear tooth cracks were not discernibly detectable from the vibration separation process. Sun gear tooth spall defects were detectable. Ring gear tooth cracks were only clearly detectable by accelerometers located near the crack location or directly across from the crack. Enveloping provided an effective method for planet bearing inner- and outer-race spalling fault detection

NALP1 in vitiligo-associated multiple autoimmune disease.

BACKGROUND: Autoimmune and autoinflammatory diseases involve interactions between genetic risk factors and environmental triggers. We searched for a gene on chromosome 17p13 that contributes to a group of epidemiologically associated autoimmune and autoinflammatory diseases. The group includes various combinations of generalized vitiligo, autoimmune thyroid disease, latent autoimmune diabetes in adults, rheumatoid arthritis, psoriasis, pernicious anemia, systemic lupus erythematosus, and Addison's disease. METHODS: We tested 177 single-nucleotide polymorphisms (SNPs) spanning the 17p13 linkage peak for association with disease and identified a strong candidate gene. We then sequenced DNA in and around the gene to identify additional SNPs. We carried out a second round of tests of association using some of these additional SNPs, thus elucidating the association with disease in the gene and its extended promoter region in fine detail. RESULTS: Association analyses resulted in our identifying as a candidate gene NALP1, which encodes NACHT leucine-rich-repeat protein 1, a regulator of the innate immune system. Fine-scale association mapping with the use of DNA from affected families and additional SNPs in and around NALP1 showed an association of specific variants with vitiligo alone, with an extended autoimmune and autoinflammatory disease phenotype, or with both. Conditional logistic-regression analysis of NALP1 SNPs indicated that at least two variants contribute independently to the risk of disease. CONCLUSIONS: DNA sequence variants in the NALP1 region are associated with the risk of several epidemiologically associated autoimmune and autoinflammatory diseases, implicating the innate immune system in the pathogenesis of these disorders