626 research outputs found

    Study of cosmic dust particles on board LDEF: The FRECOPA experiments AO138-1 and AO138-2

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    Two experiments, within the French Cooperative Payload (FRECOPA) and devoted to the detection of cosmic dust, were flown on the LDEF. A variety of sensors and collecting devices have made possible the study of impact processes on materials of technological interest. Preliminary examination of hypervelocity impact features gives valuable data on size distribution and nature of interplanetary dust particles in low earth orbit, within the 0.5 to 300 micrometer size range. Most of the events detected on the trailing face of LDEF are expected to be the result of impacts of meteoritic particles only. So far, chemical analysis of craters by EDS clearly shows evidence of elements (Na, Mg, Si, S, Ca, and Fe) consistent with cosmic origin. Systematic occurrence of C and O in crater residues is an important result, to be compared with the existence of CHON particles detected in P-Halley comet nucleus. Crater size distribution is in good agreement with results from other dust experiments flown on LDEF. However, no crater smaller than 1.5 micron was observed, thus suggesting a cutoff in the near earth particle distribution. Possible origin and orbital evolution of micrometeoroids is discussed

    The Concordiensis, Volume 11, Number 2

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    Frontispiece: The Blue Gate in 1887 Literary: Suggestions for the Care of Eyes; The Influence of Union College upon Her Alumni; Early Days of the Concordiensis; The Meeting; Rev. Geo. A. Beattie, \u2763 Editorial: A Request; Dressing Room; Hazing; Athletics; The Proposed Endowment College News; Personal; Necrology; The College World; Books and Magazineshttps://digitalworks.union.edu/concordiensis_1887/1007/thumbnail.jp

    The Concordiensis, Volume 11, Number 10

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    Literary: History of the Class of \u2788; Class Address; Ivy Poem; Undergraduate Address; Class Poem Editorial: The Commencement; The Inauguration; Commencement Speaking; The Commencement Stage; Finis College News: The Ninety-First Commencement; Baseball Record; Resolutions of the Class of 1868 Personal: Vacation Pointshttps://digitalworks.union.edu/concordiensis_1888/1005/thumbnail.jp

    The Concordiensis, Volume 11, Number 4

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    Literary: Social Life at Union; A. Perkins; Union Alumni in the West; Judge John I. Bennett, \u2754; Love; Union College Congress; Yale and Harvard Football Game Editorial: Coming Articles College News: Facts from the New Catalogue Necrology; Personal; Books and Magazineshttps://digitalworks.union.edu/concordiensis_1887/1009/thumbnail.jp

    Can Transthoracic Echocardiography Be Used to Predict Fluid Responsiveness in the Critically Ill Patient? A Systematic Review

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    Introduction. We systematically evaluated the use of transthoracic echocardiography in the assessment of dynamic markers of preload to predict fluid responsiveness in the critically ill adult patient. Methods. Studies in the critically ill using transthoracic echocardiography (TTE) to predict a response in stroke volume or cardiac output to a fluid load were selected. Selection was limited to English language and adult patients. Studies on patients with an open thorax or abdomen were excluded. Results. The predictive power of diagnostic accuracy of inferior vena cava diameter and transaortic Doppler signal changes with the respiratory cycle or passive leg raising in mechanically ventilated patients was strong throughout the articles reviewed. Limitations of the technique relate to patient tolerance of the procedure, adequacy of acoustic windows, and operator skill. Conclusions. Transthoracic echocardiographic techniques accurately predict fluid responsiveness in critically ill patients. Discriminative power is not affected by the technique selected

    Using social networking sites for communicable disease control: innovative contact tracing or breach of confidentiality?

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    Social media applications such as Twitter, YouTube and Facebook have attained huge popularity, with more than three billion people and organizations predicted to have a social networking account by 2015. Social media offers a rapid avenue of communication with the public and has potential benefits for communicable disease control and surveillance. However, its application in everyday public health practice raises a number of important issues around confidentiality and autonomy. We report here a case from local level health protection where the friend of an individual with meningococcal septicaemia used a social networking site to notify potential contacts

    The ultimate arc: Differential displacement, oroclinal bending, and vertical axis rotation in the External Betic-Rif arc

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    The External Betic-Rif arc, which lies between the converging African and Iberian plates, is one of the tightest orogenic arcs on Earth. It is a thin-skinned fold and thrust belt formed in Miocene time around the periphery of the Alborán Domain, an older contractional orogen that underwent extensional collapse coevally with the formation of the thrust belt. Restoration of four sections across the thrust belt, together with kinematic and paleomagnetic analysis, allows a reconstruction of the prethrusting geometry of the Alborán Domain, and the identification of the following processes that contributed to the formation of the arc: (1) The Alborán Domain moved some 250 km westward relative to Iberia and Africa during the Miocene. This initiated the two limbs of the arc on its NW and SW margins, closing to the WSW in the region of Cherafat in northern Morocco. The overall convergence direction on the Iberian side of the arc was between 310° and 295°, and on the African side it was between 235° and 215°. The difference in convergence direction between the two sectors was primarily a result of the relative motion between Africa and Iberia. (2) Extensional collapse of the Alborán Domain during the Miocene modified the geometry of the western end of the arc: the Internal Rif rotated anticlockwise to form the present north trending sector of the arc, and additional components of displacement produced by extension were transferred into the external thrust belt along a series of strike-slip faults and shear zones. These allowed the limbs of the arc to rotate and extend, tightening the arc, and creating variations in the amounts and directions of shortening around the arc. The Betic sector of the arc rotated clockwise by 25° during this process, and the southern Rif rotated anticlockwise by ∼55°. (3) Oblique convergence on the two limbs of the arc, dextral in the Betics and sinistral in the southern Rif, resulted in strongly noncoaxial deformation. This had three related effects: (1) large rotations of individual thrust sheets resulted from the oblique propagation of thrusts away from the thrust front, followed by pinning and rotation as the thrust sheets peeled off, (2) continued oblique convergence resulted in distributed shear, particularly in the rear of the thrust wedge, causing rotation of stacks of thrust sheets on the scale of a few tens of kilometers, and (3) distributed shear in the orogen resulted in the rotation of folds as they amplified, the hinges migrating through the rock body, and rotating at a slower rate than the rock. These rotations were substantially larger than the bulk rotations of the limbs of the arc, and they strongly modified the orientations of folds, thrust traces, and the structural indicators of fault slip directions
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