Design concepts and performance of NASA X-band (7162 MHz/8415 MHz) transponder for deep-space spacecraft applications

The design concepts and measured performance characteristics are summarized of an X band (7162 MHz/8415 MHz) breadboard deep space transponder (DSP) for future spacecraft applications, with the first use scheduled for the Comet Rendezvous Asteroid Flyby (CRAF) and Cassini missions in 1995 and 1996, respectively. The DST consists of a double conversion, superheterodyne, automatic phase tracking receiver, and an X band (8415 MHz) exciter to drive redundant downlink power amplifiers. The receiver acquires and coherently phase tracks the modulated or unmodulated X band (7162 MHz) uplink carrier signal. The exciter phase modulates the X band (8415 MHz) downlink signal with composite telemetry and ranging signals. The receiver measured tracking threshold, automatic gain control, static phase error, and phase jitter characteristics of the breadboard DST are in good agreement with the expected performance. The measured results show a receiver tracking threshold of -158 dBm and a dynamic signal range of 88 dB

Down Among The Sleepy Hills Of Tennessee

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Simultaneous multi-band detection of Low Surface Brightness galaxies with Markovian modelling

We present an algorithm for the detection of Low Surface Brightness (LSB) galaxies in images, called MARSIAA (MARkovian Software for Image Analysis in Astronomy), which is based on multi-scale Markovian modeling. MARSIAA can be applied simultaneously to different bands. It segments an image into a user-defined number of classes, according to their surface brightness and surroundings - typically, one or two classes contain the LSB structures. We have developed an algorithm, called DetectLSB, which allows the efficient identification of LSB galaxies from among the candidate sources selected by MARSIAA. To assess the robustness of our method, the method was applied to a set of 18 B and I band images (covering 1.3 square degrees in total) of the Virgo cluster. To further assess the completeness of the results of our method, both MARSIAA, SExtractor, and DetectLSB were applied to search for (i) mock Virgo LSB galaxies inserted into a set of deep Next Generation Virgo Survey (NGVS) gri-band subimages and (ii) Virgo LSB galaxies identified by eye in a full set of NGVS square degree gri images. MARSIAA/DetectLSB recovered ~20% more mock LSB galaxies and ~40% more LSB galaxies identified by eye than SExtractor/DetectLSB. With a 90% fraction of false positives from an entirely unsupervised pipeline, a completeness of 90% is reached for sources with r_e > 3" at a mean surface brightness level of mu_g=27.7 mag/arcsec^2 and a central surface brightness of mu^0 g=26.7 mag/arcsec^2. About 10% of the false positives are artifacts, the rest being background galaxies. We have found our method to be complementary to the application of matched filters and an optimized use of SExtractor, and to have the following advantages: it is scale-free, can be applied simultaneously to several bands, and is well adapted for crowded regions on the sky.Comment: 39 pages, 18 figures, accepted for publication in A

Sequence analysis of a DNA fragment from Sinorhizobium fredii USDA257 which extends the nitrogen fixation host range of Rhizobium species NGR234 to soybean, Glycine max (L.) Merr cultivar Peking

A fragment of DNA (pBTBX) from the genome ofSinorhizobium fredii USDA257 was sequenced by shotgun strategy to identify the potential genes which enabled theRhizobium species NGR234 to fix nitrogen on soybean,Glycine max (L.) Merr cv. Peking. The total length of the cosmid is 32,824 base pairs with a GC content of 61%. A 29 open reading frames (ORF) were identified representing 71.8% (23,574 bp) of the cosmid. Out of these ORF, 96.5% (22,749 bp) were identical and similar to reported and hypothetical genes and proteins. The remaining 3.5% (825 bp) had no apparent similarity to any genes in the data base. Gene and gene products found on the DNA fragment include those involved in the synthesis of FeMo component of nitrogenase, regulation of nitrogen fixation, transport of amino acids and sugars, chemotaxis and transcriptional regulatio

Nachweis erhöhter Äthylengehalte in der Bodenluft eines von der Verdichtungschlorose befallenen Rebberges

Periodische Untersuchungen der Bodenluft einer chlorosekranken Rebparzelle, deren Boden verdichtet war, erbrachten im Vergleich zu einer unmittelbar benachbarten gesunden Parzelle häufiger hohe Äthylengehalte. In einem Großteil der Gasproben wurden Äthylenkonzentrationen über 1 ppm gemessen, die als wachstumshemmend angesehen werden.Im Gegensatz zu den meisten anderen Nährstoffen kann Eisen nur in der Zellteilungs- und Streckungszone unmittelbar hinter der Wurzelspi<tze aufgenommen werden. Es wird postuliert, daß die äthyleninduzierte Hemmung des Wurzelspitzenwachstums indirekt eine verminderte Eisenaufnahme durch die Wurzel bewirkt. Sobald ein großer Eisenbedarf auftritt, meist bei beginnender Gescheinsentwicklung, entsteht ein temporärer Eisenmangel, der in der Folge zur Chlorose führt.Evidence of increased ethylene content in the soil air of a vineyard with compaction-induced chlorosisEthylene at concentrations known to affect reet growth was found in the soil air of a chlorotic vineyard with compacted soil. Concentrations above 1 ppm were significantly more frequent in the chlorotic vineyard in comparison to the healthy field just beside. In contrast to most of the other nutrients, iron can be taken up only by growing root tips. lt is postulated that the ethylene-induced inhibition of root growth reduces the iron uptake. As seen as the plant needs a great amount of iron, i.e. during an intense growth of the shoots at the beginning ef inflorescence development, a temporary iron stress leads to the appearence of chlorosis

A weak second-order split-step method for numerical simulations of stochastic differential equations

In an analogy from symmetric ordinary differential equation numerical integrators, we derive a three-stage, weak 2nd-order procedure for Monte-Carlo simulations of Itô stochastic differential equations. Our composite procedure splits each time step into three parts: an $$h/2$$ h / 2 -stage of trapezoidal rule, an $$h$$ h -stage martingale, followed by another $$h/2$$ h / 2 -stage of trapezoidal rule. In $$n$$ n time steps, an $$h/2$$ h / 2 -stage deterministic step follows another $$n-1$$ n - 1 times. Each of these adjacent pairs may be combined into a single $$h$$ h -stage, effectively producing a two-stage method with partial overlap between successive time steps

Direct CP Violation in B decays with rho0-omega Mixing

A complete study of the process B to pi+ pi- V(V=1--) is performed both in the framework of the helicity formalism and the effective lagrangian approach. Emphasis is put on the factorization hypothesis and the importance of the rho0- omega mixing in enhancing the direct CP violation. New results involving some branching ratios and the ratio of the Penguin/Tree amplitude are given in details.Comment: 7 pages, 2 figures. Talk oresented by ZJA at the 18th International Workshop on High energy Physics and Quantum Field Theory, QFTHEP004, St-Petersbug, RUSSIA, JUne 17-23, 200

Put Your Arms Where They Belong (For They Belong To Me)

With Ukulele arrangement. Contains advertisements and/or short musical examples of pieces being sold by publisher.https://digitalcommons.library.umaine.edu/mmb-vp/7116/thumbnail.jp

Radiative damping: a case study

We are interested in the motion of a classical charge coupled to the Maxwell self-field and subject to a uniform external magnetic field, B. This is a physically relevant, but difficult dynamical problem, to which contributions range over more than one hundred years. Specifically, we will study the Sommerfeld-Page approximation which assumes an extended charge distribution at small velocities. The memory equation is then linear and many details become available. We discuss how the friction equation arises in the limit of "small" B and contrast this result with the standard Taylor expansion resulting in a second order equation for the velocity of the charge.Comment: 4 figure