Isotopic composition of lead from Balmat, New York

1968 ◽  
Vol 5 (5) ◽  
pp. 1239-1245 ◽  
Author(s):  
P. H. Reynolds ◽  
R. D. Russell

Isotopic data obtained by means of gas-source mass spectrometric analyses of tetramethyllead are reported for rock and ore leads from Balmat, New York. On the basis of these new precise analyses (an uncertainty in measured isotope ratios of approximately ± 0.10% at the 95% confidence level), the Balmat ores were formed from lead isotopically of the type observed by Ostic et al. (1967) in certain conformable deposits. In a case where there is a low concentration of lead in the ore, contamination of the ore lead by lead from a rock system is apparent. The rock leads (from potassium feldspars and from marbles) form a short-period anomalous suite apparently derived from source material with a μ-value of about 8.75. This short-term development took place approximately 1100 m.y. ago. It is clear that the primary system postulated for the rock leads (μ = 8.75) is distinctly different from the one associated with the ores (μ = 9.0); hence the ore lead is not genetically related to the lead in the rock system. The apparent existence of two primary lead systems in the earth must be explained by any geophysical model that attempts to describe in general terms the evolution of lead isotope ratios.

1967 ◽  
Vol 4 (2) ◽  
pp. 245-269 ◽  
Author(s):  
R. G. Ostic ◽  
R. D. Russell ◽  
R. L. Stanton

This paper pursues the study of an apparent correlation between lead isotope abundance characteristics and features of the deposits in which the lead is discovered. New and precise analyses have been carried out on 55 galena samples, mostly From Australasian ore deposits classified as stratiform. To help clarify the interpretation, certain vein leads related to those which are stratiform have been included, as has one analysis of volcanic cotunnite.New evidence is offered that all leads began their isotopic evolution in a unique primary system which has very restricted spatial variation in the ratios U/Pb and Th/Pb. Leads from certain stratiform deposits approach more closely in isotopic composition the products of the primary system than do vein leads, many of which involve extensive crustal histories thai further modify the isotope ratios. The analyses presented here have sufficient precision to permit a close examination of the differences in isotope ratios between stratiform leads and the products of a simplified model for the primary system. The differences are significant and important.Novel aspects of the experimental technique are discussed.


Author(s):  
R. Rajesh ◽  
M.J. Kim ◽  
J.S. Bow ◽  
R.W. Carpenter ◽  
G.N. Maracas

In our previous work on MBE grown low temperature (LT) InP, attempts had been made to understand the relationships between the structural and electrical properties of this material system. Electrical measurements had established an enhancement of the resistivity of the phosphorus-rich LT InP layers with annealing under a P2 flux, which was directly correlated with the presence of second-phase particles. Further investigations, however, have revealed the presence of two fundamentally different types of precipitates. The first type are the surface particles, essentially an artefact of argon ion milling and containing mostly pure indium. The second type and the one more important to the study are the dense precipitates in the bulk of the annealed layers. These are phosphorus-rich and are believed to contribute to the improvement in the resistivity of the material.The observation of metallic indium islands solely in the annealed LT layers warranted further study in order to better understand the exact reasons for their formation.


2009 ◽  
Vol 14 (3) ◽  
pp. 3-6
Author(s):  
Robert J. Barth

Abstract “Posttraumatic” headaches claims are controversial because they are subjective reports often provided in the complex of litigation, and the underlying pathogenesis is not defined. This article reviews principles and scientific considerations in the AMAGuides to the Evaluation of Permanent Impairment (AMA Guides) that should be noted by evaluators who examine such cases. Some examples in the AMA Guides, Sixth Edition, may seem to imply that mild head trauma can cause permanent impairment due to headache. The author examines scientific findings that present obstacles to claiming that concussion or mild traumatic brain injury is a cause of permanent headache. The World Health Organization, for example, found a favorable prognosis for posttraumatic headache, and complete recovery over a short period of time was the norm. Other studies have highlighted the lack of a dose-response correlation between trauma and prolonged headache complaints, both in terms of the frequency and the severity of trauma. On the one hand, scientific studies have failed to support the hypothesis of a causative relationship between trauma and permanent or prolonged headaches; on the other hand, non–trauma-related factors are strongly associated with complaints of prolonged headache.


2016 ◽  
Vol 4 (2) ◽  
Author(s):  
Yoan Martínez Márquez ◽  
Yalice Gámez Batista ◽  
Norberto Valcárcel Izquierdo

Las TIC median las interacciones y la comunicación de los estudiantes a diario. Se conciben como mediado-ras de la reflexión y la autorregulación de la actividad del estudiante, resultante de la interacción consciente de la percepción que tiene el estudiante sobre si con la que negocia con el resto de los estudiantes, los ase-sores y la sociedad en general. En este contexto el aprovechamiento de las TIC debe promover una influen-cia formativa en los espacios formales y no formales. Las condicionantes de complementariedad de espa-cios y de unidad en la diversidad de recursos tecnológicos y didácticos deben guiar la actividad que tenga al estudiante como centro de la misma.Ya no se trata de integrar las TIC en el proceso de formación, haciéndolo formal y estandarizado. El reto está en que sean las características personales de los estudiantes, sus estilos de aprendizaje, sus conoci-mientos y experiencias previas, y sus esquemas afectivos los que marquen el aprovechamiento de las TIC en la evaluación del aprendizaje autónomo de inglés.En el presente trabajo se estructura el aprovechamiento de las TIC mediante un EPA base para la evalua-ción del aprendizaje autónomo de inglés. El EPA base constituye un andamiaje de personas, procedimien-tos, espacios de interacción, y de recursos tecnológicos y didácticos. Los componentes que lo conforman se encuentran débilmente acoplados por la tecnología y altamente cohesionados por la significatividad de las conexiones que el estudiante establece entre ellos. Palabras Clave: Aprendizaje, Autonomía, Entorno, Evaluación, Personal. ABSTRACT There is no doubt about the key role of ICT in the interaction and communication processes among students. ICT are thought as a mean for the reflection and self-regulation of students´ activity, which is in a permanent conscientious comparison between the perception a student has about him/herself and the one he/she nego-tiates with the rest of students, advisors and society in general terms. In this context, ICT should promote a positive influence on student formation in formal and non-formal spaces. The conditionals related to spaces combined support and union in the diversity of technological and didactical resources should guide every activity having students at the center of its conception.It is no longer about integrating ICT to the formation process making it formal and standardized. The chal-lenge on autonomous language learning evaluation with ICT has to do with making the differences through personal characteristics of students, their learning styles, previous experiences and affective schemas.In this paper the use of ICT is structured by means of a PLE frame for the evaluation of English autonomous language learning. It is a scaffolding of people, procedures, interaction spaces, and technological and didac-tical resources. Its components are weakly coupled by technologies and highly cohesive by the meaningful connections students establish among them. Keywords: Learning, Autonomy, Evaluation, Environment, Personal. Recibido: septiembre de 2016Aprobado: noviembre de 2016


2019 ◽  
Vol 26 (7-8) ◽  
pp. 459-474
Author(s):  
Saeed Mahmoudkhani ◽  
Hodjat Soleymani Meymand

The performance of the cantilever beam autoparametric vibration absorber with a lumped mass attached at an arbitrary point on the beam span is investigated. The absorber would have a distinct feature that in addition to the two-to-one internal resonance, the one-to-three and one-to-five internal resonances would also occur between flexural modes of the beam by tuning the mass and position of the lumped mass. Special attention is paid on studying the effect of these resonances on increasing the effectiveness and extending the range of excitation amplitudes at which the autoparametric vibration absorber remains effective. The problem is formulated based on the third-order nonlinear Euler–Bernoulli beam theory, where the assumed-mode method is used for deriving the discretized equations of motion. The numerical continuation method is then applied to obtain the frequency response curves and detect the bifurcation points. The harmonic balance method is also employed for detecting the type of internal resonances between flexural modes by inspecting the frequency response curves corresponding to different harmonics of the response. Parametric studies on the performance of the absorber are conducted by varying the position and mass of the lumped mass, while the frequency ratio of the primary system to the first mode of the beam is kept equal to two. Results indicated that the one-to-five internal resonance is especially responsible for the considerable enhancement of the performance.


Author(s):  
Coby Klein ◽  
Mitchell Baker ◽  
Andrei Alyokhin ◽  
David Mota-Sanchez

Abstract Eastern New York State is frequently the site of Colorado potato beetle (Leptinotarsa decemlineata, Say) populations with the highest observed levels of insecticide resistance to a range of active ingredients. The dominance of a resistant phenotype will affect its rate of increase and the potential for management. On organic farms on Long Island, L. decemlineata evolved high levels of resistance to spinosad in a short period of time and that resistance has spread across the eastern part of the Island. Resistance has also emerged in other parts of the country as well. To clarify the level of dominance or recessiveness of spinosad resistance in different parts of the United States and how resistance differs in separate beetle populations, we sampled in 2010 beetle populations from Maine, Michigan, and Long Island. In addition, a highly resistant Long Island population was assessed in 2012. All populations were hybridized with a laboratory-susceptible strain to determine dominance. None of the populations sampled in 2010 were significantly different from additive resistance, but the Long Island population sampled in 2012 was not significantly different from fully recessive. Recessive inheritance of high-level resistance may help manage its increase.


1984 ◽  
Vol 98 (2) ◽  
pp. 98-109 ◽  
Author(s):  
J. Bruyn

AbstractFrom 1911 to 1961 Félix Chrétien, secretary to François de Dinteville II, Bishop of Auxerre in Burgundy, and from 1542 onwards a canon in that town, was thought to be the author of three remarkable paintings. Two of these were mentioned by an 18th-century local historian as passing for his work: a tripych dated 1535 on the central panel with scenes from the legend of St. Eugenia, which is now in the parish church at Varzy (Figs. 1-3, cf. Note 10), and a panel dated 1550 with the Martyrdom of St. Stephen in the ambulatory of Auxerre Cathedral. To these was added a third work, a panel dated 1537 with Moses and Aaron before Pharaoh, which is now in New York (Figs. 4-5, cf. Notes I and 3). All three works contain a portrait of François de Dinteville, who is accompanied in the Varzy triptych and the New York panel (where he figures as Aaron) by other portrait figures. In the last-named picture these include his brothers) one of whom , Jean de Dinteville, is well-known as the man who commissioned Holbein's Ambassadors in 1533. Both the Holbein and Moses and Aaron remained in the family's possession until 1787. In order to account for the striking affinity between the style of this artist and that of Netherlandish Renaissance painters, Jan van Scorel in particular, Anthony Blunt posited a common debt to Italy, assuming that the painter accompanied François de Dinteville on a mission to Rome in 1531-3 (Note 4). Charles Sterling) on the other hand, thought of Netherlandish influence on him (Note 5). In 1961 Jacques Thuillier not only stressed the Northern features in the artist's style, especially in his portraits and landscape, but also deciphered Dutch words in the text on a tablet depicted in the Varzy triptych (Fig. I) . He concluded that the artist was a Northerner himself and could not possibly have been identical with Félix Chrétien (Note 7). Thuillier's conclusion is borne out by the occurrence of two coats of arms on the church depicted in the Varzy triptych (Fig. 2), one of which is that of a Guild of St. Luke, the other that of the town of Haarlem. The artist obviously wanted it to be known that he was a master in the Haarlem guild. Unfortunately, the Haarlem guild archives provide no definite clue as to his identity. He may conceivably have been Bartholomeus Pons, a painter from Haarlem, who appears to have visited Rome and departed again before 22 June 15 18, when the Cardinal of S. Maria in Aracoeli addressed a letter of indulgence to him (without calling him a master) care of a master at 'Tornis'-possibly Tournus in Burgundy (Note 11). The name of Bartholomeus Pons is further to be found in a list of masters in the Haarlem guild (which starts in 1502, but gives no further dates, Note 12), while one Bartholomeus received a commission for painting two altarpiece wings and a predella for Egmond Abbey in 1523 - 4 (Note 13). An identification of the so-called Félix Chrétien with Batholomeus Pons must remain hypothetical, though there are a number of correspondences between the reconstructed career of the one and the fragmentary biography of the other. The painter's work seems to betray an early training in a somewhat old-fashioned Haarlem workshop, presumably around 1510. He appears to have known Raphael's work in its classical phase of about 1515 - 6 and to have been influenced mainly by the style of the cartoons for the Sistine tapestries (although later he obviously also knew the Master of the Die's engravings of the story of Psyche of about 1532, cf .Note 8). His stylistic development would seem to parallel that of Jan van Scorel, who was mainly influenced by the slightly later Raphael of the Loggie. This may explain the absence of any direct borrowings from Scorel' work. It would also mean that a more or less Renaissance style of painting was already being practised in Haarlem before Scorel's arrival there in 1527. Thuillier added to the artist's oeuvre a panel dated 1537 in Frankfurt- with the intriguing scene of wine barrels being lowered into a cellar - which seems almost too sophisticated to be attributed to the same hand as the works in Varzy and New York, although it does appear to come from the same workshop (Fig. 6, Note 21). A portrait of a man, now in the Louvre, was identified in 197 1 as a fragment of a work by the so-called Félix Chrétien himself (Fig. 8, Note 22). The Martyrdom of St. Stephen of 1550 was rejected by Thuillier because of its barren composition and coarse execution. Yet it seems to have too much in common with the other works to be totally separated, from them and may be taken as evidence that the workshop was still active at Auxerre in 1550.


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