8,756 research outputs found
Antenna simulator permits preinstallation system checkout
Antenna simulator provides for evaluation checkout of corporate feeds, monopulse sum-and-difference networks, etc., in a shielded environment prior to system checkout on an antenna pattern range. This technique is useful wherever simulation of monopulse antenna element characteristics is desired for checkout of ancillary equipment in a controlled environment
Monopulse system with an electronic scanner
Electronic and mechanical scanning control system for monopulse tracking antenn
Not a galaxy: IRAS 04186+5143, a new young stellar cluster in the outer Galaxy
We report the discovery of a new young stellar cluster in the outer Galaxy
located at the position of an IRAS PSC source that has been previously
mis-identified as an external galaxy. The cluster is seen in our near-infrared
imaging towards IRAS 04186+5143 and in archive Spitzer images confirming the
young stellar nature of the sources detected. There is also evidence of
sub-clustering seen in the spatial distributions of young stars and of gas and
dust.
Near- and mid-infrared photometry indicates that the stars exhibit colours
compatible with reddening by interstellar and circumstellar dust and are likely
to be low- and intermediate-mass YSOs with a large proportion of Class I YSOs.
Ammonia and CO lines were detected, with the CO emission well centred near
the position of the richest part of the cluster. The velocity of the CO and
NH lines indicates that the gas is Galactic and located at a distance of
about 5.5 kpc, in the outer Galaxy.
Herschel data of this region characterise the dust environment of this
molecular cloud core where the young cluster is embedded. We derive masses,
luminosities and temperatures of the molecular clumps where the young stars
reside and discuss their evolutionary stages.Comment: 14 pages, 15 figure
Clinical trial: protective effect of a commercial fish protein hydrolysate against indomethacin (NSAID)-induced small intestinal injury
Background A partially hydrolysed and dried product of pacific whiting fish is marketed as a health food supplement supporting 'intestinal health'.Aim To examine whether the partially hydrolysed and dried product of pacific whiting fish influenced the small intestinal damaging side effects of the nonsteroidal anti-inflammatory drug, indomethacin.Methods Eight human volunteers completed a double-blind, placebo-controlled, crossover protocol of clinically relevant dose of indomethacin (50 mg t.d.s. p.o. for 5 days) with 7 days of fish hydrolysate or placebo starting 2 days prior to indomethacin. Changes in gut permeability were assessed using 5 h urinary lactulose:rhamnose (L/R) ratios.Results Fish hydrolysate given alone did not affect permeability. In the main study (n = 8), baseline values were similar for both arms (0.28 +/- 0.05 and 0.35 +/- 0.07). Administration of indomethacin (+placebo) caused a fivefold rise in L/R ratios (increasing to 1.54 +/- 0.35), whereas L/R ratios in the same subjects ingesting indomethacin + fish hydrolysate was only 0.59 +/- 0.14 (P < 0.01 vs. indomethacin alone). Dyspeptic symptoms occurred in four of eight subjects taking indomethacin alone, but zero of eight when hydrolysate was co-administered.Conclusion Natural bioactive products (nutriceuticals), such as fish hydrolysates, may provide a novel approach to the prevention and treatment of NSAID-induced and other gastrointestinal injurious conditions
Task oriented nonlinear control laws for telerobotic assembly operations
The goal of this research is to achieve very intelligent telerobotic controllers which are capable of receiving high-level commands from the human operator and implementing them in an adaptive manner in the object/task/manipulator workspace. Initiatives by the authors at Integrated Systems, Inc. to identify and develop the key technologies necessary to create such a flexible, highly programmable, telerobotic controller are presented. The focus of the discussion is on the modeling of insertion tasks in three dimensions and nonlinear implicit force feedback control laws which incorporate tool/workspace constraints. Preliminary experiments with dual arm beam assembly in 2-D are presented
The Structure of Rural Landscape in Monetary Evaluation Studies: Main Analytical Approaches in Literature
Over recent years considerable research has been devoted to the assessment of the rural landscape value. These studies have concerned both use and non-use value estimation. An important issue in monetary evaluations is about taking (or not) into account the structural complexity of landscape. Three analytical approaches may be recognized on the basis of whether landscape structural attributes are involved (global, mono-attribute and multi-attribute approach). The present work is part of a research aimed to seek out rational instruments for guidance policies on rural landscape. It consists in a survey of the main studies appeared in literature. The specific purpose is to classify these empirical analyses in accordance both to the approaches mentioned above and to the landscape typologies (agricultural or forestry) involved.rural landscape, structural attributes, landscape demand, contingent valuation models, choice experiment, Land Economics/Use, Q26,
Explicit Space-Time Codes Achieving The Diversity-Multiplexing Gain Tradeoff
A recent result of Zheng and Tse states that over a quasi-static channel,
there exists a fundamental tradeoff, referred to as the diversity-multiplexing
gain (D-MG) tradeoff, between the spatial multiplexing gain and the diversity
gain that can be simultaneously achieved by a space-time (ST) block code. This
tradeoff is precisely known in the case of i.i.d. Rayleigh-fading, for T>=
n_t+n_r-1 where T is the number of time slots over which coding takes place and
n_t,n_r are the number of transmit and receive antennas respectively. For T <
n_t+n_r-1, only upper and lower bounds on the D-MG tradeoff are available.
In this paper, we present a complete solution to the problem of explicitly
constructing D-MG optimal ST codes, i.e., codes that achieve the D-MG tradeoff
for any number of receive antennas. We do this by showing that for the square
minimum-delay case when T=n_t=n, cyclic-division-algebra (CDA) based ST codes
having the non-vanishing determinant property are D-MG optimal. While
constructions of such codes were previously known for restricted values of n,
we provide here a construction for such codes that is valid for all n.
For the rectangular, T > n_t case, we present two general techniques for
building D-MG-optimal rectangular ST codes from their square counterparts. A
byproduct of our results establishes that the D-MG tradeoff for all T>= n_t is
the same as that previously known to hold for T >= n_t + n_r -1.Comment: Revised submission to IEEE Transactions on Information Theor
Polynomial evaluation over finite fields: new algorithms and complexity bounds
An efficient evaluation method is described for polynomials in finite fields.
Its complexity is shown to be lower than that of standard techniques when the
degree of the polynomial is large enough. Applications to the syndrome
computation in the decoding of Reed-Solomon codes are highlighted.Comment: accepted for publication in Applicable Algebra in Engineering,
Communication and Computing. The final publication will be available at
springerlink.com. DOI: 10.1007/s00200-011-0160-
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