Scanning mirror for infrared sensors

A high resolution, long life angle-encoded scanning mirror, built for application in an infrared attitude sensor, is described. The mirror uses a Moire' fringe type optical encoder and unique torsion bar suspension together with a magnetic drive to meet stringent operational and environmental requirements at a minimum weight and with minimum power consumption. Details of the specifications, design, and construction are presented with an analysis of the mirror suspension that allows accurate prediction of performance. The emphasis is on mechanical design considerations, and brief discussions are included on the encoder and magnetic drive to provide a complete view of the mirror system and its capabilities

Procedure for noise prediction and optimization of advanced technology propellers

The sound field due to a propeller operating at supersonic tip speed in a uniform flow was investigated. Using the fact that the wave front in a uniform stream is a convected sphere, the fundamental solution to the convected wave equation was easily obtained. The Fourier coefficients of the pressure signature were obtained by a far field approximation, and are expressed as an integral over the blade platform. It is shown that cones of silence exist fore and aft the propeller plane. The semiapex angles are shown. These angles are independent of the individual Mach components such as the flight Mach number and the rotation Mach number. The result is confirmed by the computation of the ray path of the emitted Mach waves. The Doppler amplification factor strengthens the signal behind the propeller while it weakens that upstream

Comparing teacher roles in Denmark and England

This article reports the findings of a comparative study of teaching in Denmark and England; its broader aim is to help develop an approach for comparing pedagogy. Lesson observations and interviews identified the range of goals towards which teachers in each country worked and the actions these prompted. These were clustered using the lens of Bernstein’s pedagogic discourse (1990; 1996) to construct teacher roles which provided a view of pedagogy. Through this approach we have begun to identify variations in pedagogy across two countries. All teachers in this study adopted a variety of roles; of significance was the ease with which competent English teachers moved between roles. The English teachers observed adopted roles consistent with a wider techno-rationalist discourse. There was a greater subject emphasis by Danish teachers whose work was set predominantly within a democratic humanist discourse, whilst the English teachers placed a greater emphasis on applied skills

On the role of entanglement in quantum computational speed-up

For any quantum algorithm operating on pure states we prove that the presence of multi-partite entanglement, with a number of parties that increases unboundedly with input size, is necessary if the quantum algorithm is to offer an exponential speed-up over classical computation. Furthermore we prove that the algorithm can be classically efficiently simulated to within a prescribed tolerance \eta even if a suitably small amount of global entanglement (depending on \eta) is present. We explicitly identify the occurrence of increasing multi-partite entanglement in Shor's algorithm. Our results do not apply to quantum algorithms operating on mixed states in general and we discuss the suggestion that an exponential computational speed-up might be possible with mixed states in the total absence of entanglement. Finally, despite the essential role of entanglement for pure state algorithms, we argue that it is nevertheless misleading to view entanglement as a key resource for quantum computational power.Comment: Main proofs simplified. A few further explanatory remarks added. 22 pages, plain late

Management of neonates after postpartum discharge and all children in the ambulatory setting during the coronavirus disease 2019 (COVID-19) pandemic

PURPOSE OF REVIEW: The present coronavirus disease 2019 (COVID-19) pandemic has created additional challenges with an increased number of presumed healthy, full-term newborns being discharged at 24 h after delivery. Short lengths of stay raise the possibility of mother-infant dyads being less ready for discharge, defined as at least one of the three informants (i.e., mother, pediatrician, and obstetrician) believing that either the mother and/or infant should stay longer than the proposed time of discharge. This public health crisis has reduced the number of in-person well child visits, negatively impacting vaccine receipt, and anticipatory guidance. RECENT FINDINGS: Extra precautions should be taken during the transition period between postpartum discharge and follow-up in the ambulatory setting to ensure the safety of all patients and practice team members. This should include restructuring office flow by visit type and location, limiting in-person visits during well infant exams, instituting proper procedures for personal protective equipment and for cleaning of the office, expanding telehealth capabilities for care and education, and prioritizing universal vaccinations and routine well child screenings. SUMMARY: Based on current limited evidence, this report provides guidance for the postdischarge management of newborns born to mothers with confirmed or suspected disease in the ambulatory setting as well as prioritizing universal immunizations and routine well child screenings during the COVID-19 pandemic

Necrosis in grapevine buds (Vitis vinifera cv. Queen of Vineyard) I. Relation to vegetative vigor1)

A study on the occurrence, development and nature of necrotic buds on shoots of the Queen of Vineyard grape cultivar was carried out in the continental Jordan Valley in Israel. A vigorous vineyard having an abundance of necrotic buds and a moderately growing one with few necrotic buds were chosen.Necrosis of the central bud in the Queen of Vineyard winter buds occurred only in the vigorous vineyard. The number of necrotic dry buds was particularly high at nodes 2-3 on the shoot and decreased progressively up to the 7th node above which necrotic buds were not observed. Drying of the central bud occurred over a short period, 15-20 d after bloom. It started with the appearance of a necrotic layer at one of the basal nodes of the central bud which caused a rapid degeneration of the tissues above this layer. A negative correlation was found between the fruiting potential of winter buds and the development of a necrotic layer. The possible relation between vigor, gibberellins and bud necrosis is discussed.Knospennekrosen bei der Rebsorte Queen of Vineyard (Vitis vinifera)I. Beziehung zur vegetativen WüchsigkeitIm binnenländischen Jordantal in Israel wurde eine Untersuchung über Auftreten, Entwicklung und Art von Knospennekrosen an den Trieben der Rebsorte Queen of Vineyard durchgeführt. Hierzu wurden ein wüchsiger Weinberg, in dem nekrotische Knospen gehäuft vorkamen, und ein Weinberg von mittlerer Wüchsigkeit mit wenigen nekrotischen Knospen ausgewählt. In den Winterknospen von Queen of Vineyard trat eine Nekrose der Mittelknospe nur in der wüchsigen Rebanlage auf. Die Anzahl vertrockneter nekrotischer Knospen war besonders hoch an den Knoten 2-3 der Triebe; sie ging stetig zurück bis zum 7. Knoten; darüber wurden keine nekrotischen Knospen mehr beobachtet. Die Austrocknung der Mittelknospe erfolgte nur während einer kurzen Phase, 15-20 d nach der Blüte. Sie begann mit dem Auftreten einer nekrotischen Schicht an einem der basalen Knoten der Mittelknospe, wodurch die darüberliegenden Gewebe rasch degenerierten. Zwischen der potentiellen Fruchtbarkeit der Winterknospen und der Entwicklung einer nekrotischen Schicht wurde eine negative Korrelation gefunden. Die mögliche Beziehung zwischen Wüchsigkeit, Gibberellingehalt und Nekrosenhäufigkeit wird diskutiert

Necrosis in grapevine buds (Vitis vinifera cv. Queen of Vineyard) II. Effect of gibberellic acid (GA3) application

The effect of gibberellic acid application on the development of necrosis in cv. Queen of Vineyard grapevine buds was studied. GA3 caused the development of a necrotic layer at the base of the central bud and promoted the development of the  axillary buds. GA3 application to leaves caused necrosis in the buds more readily than direct application to the buds. GA3 fed to the petiole was 100 times more active in inducing necrosis than leaf application. Only developing and relatively young buds were sensitive to GA3. A minimum of 6 X 10-6 mg GA3 in the bud was needed to cause bud necrosis. During the period from 1 week before to 3 weeks after bloom, the movement of GA3 in the grape shoot was acropetal. The possible involvement of gibberellins in the natural necrosis of buds on vigorous grapevines is discussed.Knospennekrosen bei der Rebsorte Queen of Vineyard (Vitis vinifera)II. Einfluß der Gibberellinsäure- (GA3)BehandlungBei der Sorte Queen of Vineyard wurde der Einfluß der GA3-Behandlung auf die Entwicklung von Knospennekrosen untersucht. GA3 bewirkte die Ausbildung einer nekrotischen Gewebeschicht an der Basis der Mittelknospe und förderte die Entwicklung der Axillarknospen. Durch GA3-Behandlung der Blätter ließen sich leichter Knospennekrosen auslösen als durch direkte Behandlung der Knospen. Wurde GA3 über den Blattstiel zugeführt, so war seine Nekrosen induzierende Wirkung 100mal stärker als bei Behandlung der Blattspreite. Nur sich entwickelnde und relativ junge Knospen waren gegen GA3 sensibel. Um eine Knospennekrose auszulösen, mußten in den Knospen mindestens 6 X 10-6 mg GA3 vorliegen. Zwischen 1 Woche vor und 3 Wochen nach der Blüte erfolgte die Bewegung des GA3in den Rebentrieben akropetal. Die mögliche Beteiligung von Gibberellinen am natürlichen Auftreten von Knospennekrosen bei wüchsigen Reben wird diskutiert