Delay line and mutual coupling considerations for MST radar antenna arrays

Basic antenna theory which states that the field radiated from an antenna array is equal to the sum of the currents flowing in each element of the array is discussed. The feedline distribution system guarantees the proper amplitude and phase of the current for each element of an array. The difference in electrical lengths of the feedlines to the elements has to equal the desired phase angle. The current for voltage delay in a transmission line is equal to the transmission line electrical length in only a few special cases, when the transmission line is terminated in its characteristic impedance or when the transmission line's electrical length is a multiple of 90 degrees

Design considerations for high-power VHF radar transceivers (keynote paper)

A review and analysis of conference papers addressing the design of high power VHF radar tranceivers is presented. Specific design topics include: (1) distributed versus single transmitters; (2) coded pulses and decoder design; (3) large transmitter design considerations; and (4) T/R switch design. The topics in the discussion on future directions include the following: (1) enhanced receiver performance; (2) transmitter systems for unattended operation; (3) limitations of the current T/R switch designs; (4) data processing (is eight bits enough); and (5) new frequencies (200 MHz and/or 400 MHz)

Chung-Li, Taiwan dual mode (Doppler and spaced antenna) VHF radar: Preliminary specifications

A major unresolved question in the field of atmospheric research using VHF radar techniques is the relative merit of the two most widely used systems. These systems are the Doppler method and the spaced antenna method. It has been suggested that one radar of each type be operated side by side for a direct comparison of the two techniques. This duplication of effort is not cost effective. The major components of both systems are identical, and one radar could be operated in both modes by proper design of a suitable antenna system and by proper data analysis. The Chung-Li radar will be able to switch between modes on a time scale of seconds and is the first VHF radar to be able to directly compare the Doppler data with spaced antenna data. The system will have performance comparable with the present SOUSY spaced antenna system and will provide mesospheric data in addition to stratospheric and tropospheric data. The major specifications of the Chung-Li radar are given

The Boot Lake MF imaging radar

The Middle-Atmosphere Imaging Radar is located at the Boot Lake field site, 10 miles east of Brighton, Colorado. It operates at 2.66 MHz with a 50-kW peak pulse power in 30 microsecond pulses. Ten independent coaxial-collinear antennas are used; five are parallel and run east-west, the other five are parallel and run north-south. Each antenna consists of eight half-wave dipoles. All ten antennas or a crossed pair may be used for transmission; all ten are sampled by pairs in rapid sequence for reception. The system is now operating on a campaign basis as a Fourier interferometer by measuring the complex voltages on the ten antennas and Fourier transforming them independently. Multiple scatterers within a single range gate, now sorted by velocity, can be located individually by their phase angles. The transmitted signal cycles through four modes (N-S linear, right-hand circular, E-W linear, and left-hand circular)

A high-speed digital signal processor for atmospheric radar, part 7.3A

The Model SP-320 device is a monolithic realization of a complex general purpose signal processor, incorporating such features as a 32-bit ALU, a 16-bit x 16-bit combinatorial multiplier, and a 16-bit barrel shifter. The SP-320 is designed to operate as a slave processor to a host general purpose computer in applications such as coherent integration of a radar return signal in multiple ranges, or dedicated FFT processing. Presently available is an I/O module conforming to the Intel Multichannel interface standard; other I/O modules will be designed to meet specific user requirements. The main processor board includes input and output FIFO (First In First Out) memories, both with depths of 4096 W, to permit asynchronous operation between the source of data and the host computer. This design permits burst data rates in excess of 5 MW/s

Evidence for parallel elongated structures in the mesosphere

The physical cause of partial reflection from the mesosphere is of interest. Data are presented from an image-forming radar at Brighton, Colorado, that suggest that some of the radar scattering is caused by parallel elongated structures lying almost directly overhead. Possible physical sources for such structures include gravity waves and roll vortices

A community pharmacy weight management programme: an evaluation of effectiveness

<p>Background: Community pharmacies may offer an accessible way of delivering weight-management programmes but there have been few trials that use clinically significant weight loss outcomes, objective measures of weight and follow-up to 12 months. We aimed to evaluate weight change among patients who used the Counterweight weight management programme delivered by community pharmacies.</p> <p>Methods: The Counterweight Programme was introduced into community pharmacies in Fife, Scotland in 2009 for patients with a BMI ≥ 30 kg/m2 or a BMI ≥ 28 kg/m2 with a co-morbidity in localities in which Counterweight was not available at GP practices. The aim was to achieve an energy deficit of 500-600 kcal per day. Counterweight specialist dietitians delivered training, support and patient information materials to community pharmacies. Patient weight was measured by pharmacy staff at each weight management session. Weight data recorded at each weight management session were used to estimate weight change and attendance at 3, 6 and 12 months.</p> <p>Results: Between March 2009 and July 2012, 458 patients were enrolled by the community pharmacies. Three-quarters of patients were women, mean age was 54 (SD 7.4) years and mean BMI 36.1 (SD 5.9) kg/m2. Of 314 patients enrolled for at least 12 months, 32 (10.2% on an intention to treat basis) had achieved the target weight loss of ≥5%; this was 41.6% of those who attended at 12 months representing a mean weight loss of 4.1 kg. Using Last Observation Carried Forward, 15.9% achieved the target weight loss within 12 months of enrolling. There was no significant effect of sex, baseline BMI or age on weight loss.</p> <p>Conclusions: The Counterweight pharmacy programme has a similar effectiveness to other primary care based weight management programmes and should be considered as part of a range of services available to a community to manage overweight and obesity.</p&gt

A quantitative assessment of the role of the parasite Amoebophrya in the termination of Alexandrium fundyense blooms within a small coastal embayment

© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 8 (2013): e81150, doi:10.1371/journal.pone.0081150.Parasitic dinoflagellates of the genus Amoebophrya infect free-living dinoflagellates, some of which can cause harmful algal blooms (HABs). High prevalence of Amoebophrya spp. has been linked to the decline of some HABs in marine systems. The objective of this study was to evaluate the impact of Amoebophrya spp. on the dynamics of dinoflagellate blooms in Salt Pond (MA, USA), particularly the harmful species Alexandrium fundyense. The abundance of Amoebophrya life stages was estimated 3–7 days per week through the full duration of an annual A. fundyense bloom using fluorescence in situ hybridization coupled with tyramide signal amplification (FISH- TSA). More than 20 potential hosts were recorded including Dinophysis spp., Protoperidinium spp. and Gonyaulax spp., but the only dinoflagellate cells infected by Amoebophrya spp. during the sampling period were A. fundyense. Maximum A. fundyense concentration co-occurred with an increase of infected hosts, followed by a massive release of Amoebophrya dinospores in the water column. On average, Amoebophrya spp. infected and killed ~30% of the A. fundyense population per day in the end phase of the bloom. The decline of the host A. fundyense population coincided with a dramatic life-cycle transition from vegetative division to sexual fusion. This transition occurred after maximum infected host concentrations and before peak infection percentages were observed, suggesting that most A. fundyense escaped parasite infection through sexual fusion. The results of this work highlight the importance of high frequency sampling of both parasite and host populations to accurately assess the impact of parasites on natural plankton assemblages.L. Velo-Sua´rez was supported by a Marie Curie International Outgoing Fellowship (IOF; grant agreement: MOHAB PIOF-GA-252260). This work was supported in part by NSF grants OCE-0430724 and OCE-0911031 and National Institute of Environmental Health Sciences grants 1P50-ES01274201 and 1P01ES021923-01 to D.M. Anderson and D.J. McGillicuddy through the Woods Hole Center for Oceans and Human Health, National Park Service Cooperative Agreement H238015504 to D.M. Anderson