Systems engineering analysis of aplanatic Wolter type I x-ray telescopes

It is well known that normal-incidence aplanatic telescope designs perform better at small field angles than ones corrected only for spherical aberration. This is why most large astronomical telescopes fabricated in the past fifty years have been of the Ritchey-Chretien (aplanatic) design rather than of the classical Cassegrain design. For the relatively new field of x-ray astronomy, the Welter type I grazing incidence design has been extensively utilized. It consists of a paraboloidal primary mirror coaxial with a confocal hyperboloidal secondary mirror. Aplanatic versions of the Welter type I grazing incidence x-ray telescope have been discussed in detail in the literature, and are widely touted as being superior designs. However, scattering effects from residual optical fabrication errors and other practical engineering error sources prevent these grazing-incidence telescopes from being near diffraction-limited (even on axis) at the very short operational x-ray wavelengths. A systems engineering analysis of these error sources indicates that they will dominate coma at the small field angles, and of course astigmatism, field curvature, and higher-order aberrations dominate coma at the large field angles. Hence, there is little improvement in performance when going to an aplanatic design. Comparison of performance predictions for the classical versus aplanatic Welter type I x-ray telescope are presented for the special case of the Solar X-Ray Imager (SXI) baseline design. SXI is expected to become a standard subsystem aboard the next generation of NOAA/GOES weather satellites

How a soybean plant develops

Compiled in this publication are years of research, study and observation o f exactly how a soybean plant develops. Photographs and accompanying text record the findings for each major stage of development in the soybean plant’s life.https://lib.dr.iastate.edu/specialreports/1050/thumbnail.jp

Bound States of Type I D-Strings

We study the infra-red limit of the O(N) gauge theory that describes the low energy modes of a system of $N$ type I D-strings and provide some support to the conjecture that, in this limit, the theory flows to an orbifold conformal theory. We compute the elliptic genus of the orbifold theory and argue that its longest string sector describes the bound states of D-strings. We show that, as a result, the masses and multiplicities of the bound states are in agreement with the predictions of heterotic-type I duality in 9 dimensions, for all the BPS charges in the lattice $\Gamma_{(1,17)}$.Comment: 14 pages, (AMS-)LaTex file using amstex.st

Mal/SRF Is Dispensable for Cell Proliferation in Drosophila

The Mal/SRF transcription factor is regulated by the level of G-actin in cells and has important roles in cell migration and other actin-dependent processes in Drosophila. A recent report suggests that Mal/SRF and an upstream regulator, Pico, are required for cell proliferation and tissue growth in Drosophila. I find otherwise. Mutation of Mal or SRF does not affect cell proliferation in the fly wing. Furthermore, I cannot reproduce the reported effects of Pico RNAi or Pico overexpression on body size. Nevertheless, I can confirm that overexpression of Pico or Mal causes tissue overgrowth specifically in the fly wing - where SRF is most highly expressed. My results indicate that Mal/SRF can promote tissue growth when abnormally active, but is not normally required for tissue growth during development

Fostering collective intelligence education

New educational models are necessary to update learning environments to the digitally shared communication and information. Collective intelligence is an emerging field that already has a significant impact in many areas and will have great implications in education, not only from the side of new methodologies but also as a challenge for education. This paper proposes an approach to a collective intelligence model of teaching using Internet to combine two strategies: idea management and real time assessment in the class. A digital tool named Fabricius has been created supporting these two elements to foster the collaboration and engagement of students in the learning process. As a result of the research we propose a list of KPI trying to measure individual and collective performance. We are conscious that this is just a first approach to define which aspects of a class following a course can be qualified and quantified.Postprint (published version

Rate versus rhythm control and outcomes in patients with atrial fibrillation and chronic kidney disease: Data from the GUSTO-III Trial

Background: Atrial fi brillation (AF) and chronic kidney disease (CKD) have both beenshown to portend worse outcomes after acute myocardial infarction (MI); however, the benefi tof a rhythm control strategy in patients with CKD post-MI is unclear.Methods: We prospectively studied 985 patients with new-onset AF post-MI in theGUSTO-III trial, of whom 413 (42%) had CKD (creatinine clearance < 60 mL/min).A rhythm control strategy, defi ned as the use of an antiarrhythmic medication and/orelectrical cardioversion, was used in 346 (35%) of patients.Results: A rhythm control strategy was used in 34% of patients with CKD and 36% of patientswith no CKD. At hospital discharge, sinus rhythm was present in 487 (76%) of patients treatedwith a rate control strategy, vs. 276 (80%) in those treated with rhythm control (p = 0.20). CKDwas associated with a lower odds of sinus rhythm at discharge (unadjusted OR 0.56, 95% CI0.38–0.84, p < 0.001). However, in multivariable analyses, treatment with a rhythm controlstrategy was not associated with discharge rhythm (HR 1.068, 95% CI 0.69–1.66, p = 0.77),30-day mortality (HR 0.78, 95% CI 0.54–1.12, p = 0.18) or mortality from day 30 to 1 year(HR 1.00, 95% CI 0.59–1.69, p = 0.99). CKD status did not signifi cantly impact the relationshipbetween rhythm control and outcomes.Conclusions: Treatment with a rhythm or rate control strategy does not signifi cantly impactshort-term or long-term mortality in patients with post-MI AF, regardless of kidney disease status.Future studies to investigate the optimal management of AF in CKD patients are needed

Formation of Episodic Magnetically Driven Radiatively Cooled Plasma Jets in the Laboratory

We report on experiments in which magnetically driven radiatively cooled plasma jets were produced by a 1 MA, 250 ns current pulse on the MAGPIE pulsed power facility. The jets were driven by the pressure of a toroidal magnetic field in a ''magnetic tower'' jet configuration. This scenario is characterized by the formation of a magnetically collimated plasma jet on the axis of a magnetic ''bubble'', confined by the ambient medium. The use of a radial metallic foil instead of the radial wire arrays employed in our previous work allows for the generation of episodic magnetic tower outflows which emerge periodically on timescales of ~30 ns. The subsequent magnetic bubbles propagate with velocities reaching ~300 km/s and interact with previous eruptions leading to the formation of shocks.Comment: 6 pages, 5 figures. Accepted for publication in Astrophysics & Space Scienc

175 GHz, 400-fs-pulse harmonically mode-locked surface emitting semiconductor laser

We report a harmonically mode-locked vertical external cavity surface emitting laser (VECSEL) producing 400 fs pulses at a repetition frequency of 175 GHz with an average output power of 300 mW. Harmonic mode-locking was established using a 300 µm thick intracavity single crystal diamond heat spreader in thermal contact with the front surface of the gain sample using liquid capillary bonding. The repetition frequency was set by the diamond microcavity and stable harmonic mode locking was achieved when the laser cavity length was tuned so that the laser operated on the 117th harmonic of the fundamental cavity. When an etalon placed intracavity next to the gain sample, but not in thermal contact was used pulse groups were observed. These contained 300 fs pulses with a spacing of 5.9 ps. We conclude that to achieve stable harmonic mode locking at repetition frequencies in the 100s of GHz range in a VECSEL there is a threshold pulse energy above which harmonic mode locking is achieved and below which groups of pulses are observed

E.P. Thompson and cultural sociology: questions of poetics, capitalism and the commons

There is currently a need for cultural sociology to readdress the work of humanistic and cultural Marxism. While more recently much of this work has been dismissed the appearance of more radical social movements and the on-going crisis of neoliberalism suggests that it still has much to tell us. In this respect, this article seeks to readdress the writing of historian E.P.Thompson arguing that his work on the class based and other social movements, poetics, critique of positivism and economic reason, utopia and work on the idea of the commons all has much to offer more contemporary scholarship. While the article recognises that the cultural Marxism of figures like Thompson can-not simply be resurrected it does continue to offer a number of critical insights lacking from other traditions within cultural sociology. By readdressing the internal complexity of Thompson’s writing the argumentative strategy of this article suggests that cultural sociology needs to move beyond more simplistic understandings of cultural Marxism and more carefully explore what it has to offer