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At least 19 recordsLinked to original sources
PubMed1999

The BMP-related protein radar: a maintenance factor for dorsal neuroectoderm cells?

We have previously cloned several members of the TGF-beta superfamily of growth factors in zebrafish, one of which, Radar, belongs to the Dpp-Vg1-related (DVR) subgroup, with highest homology to GDF6. The pattern of expression of Radar suggested a possible involvement in several induction steps during embryogenesis including in the dorsal neural tube, red blood cells, the dorsal fin and the retina. We have analyzed the pattern of expression of Radar in comparison with that of a marker of dorsal neural tube structures, msxC and show that Radar and msxC are expressed in similar and/or adjacent tissues throughout embryogenesis. In order to demonstrate a functional relationship between these two proteins, we have generated a full-length cDNA for Radar and shown that Radar overexpression by DNA injection maintains expression of msxC in tissues where it is normally expressed then turned off, in particular in the dorsal neurectoderm. Study of the phenotype of a mutant carrying a deletion of Radar shows a loss of identity and death of the cells of the dorsal neural tube. Taken together these results suggest that Radar could be involved in maintaining the identity of cells of the dorsal-most neural tube and of at least a subset of neural crest cells.

Amino Acid Sequence↗
PubMed1999

Behaviour of migrating birds exposed to X-band radar and a bright light beam

Radar studies on bird migration assume that the transmitted electromagnetic pulses do not alter the behaviour of the birds, in spite of some worrying reports of observed disturbance. This paper shows that, in the case of the X-band radar 'Superfledermaus', no relevant changes in flight behaviour occurred, while a strong light beam provoked important changes. Large sets of routine recordings of nocturnal bird migrants obtained using an X-band tracking radar provided no indication of differing flight behaviour between birds flying at low levels towards the radar, away from it or passing it sideways. Switching the radar transmission on and off, while continuing to track selected bird targets using a passive infrared camera during the switch-off phases of the radar, showed no difference in the birds' behaviour with and without incident radar waves. Tracking single nocturnal migrants while switching on and off a strong searchlight mounted parallel to the radar antenna, however, induced pronounced reactions by the birds: (1) a wide variation of directional shifts averaging 8 degrees in the first and 15 degrees in the third 10 s interval after switch-on; (2) a mean reduction in flight speed of 2-3 m s-1 (15-30 % of normal air speed); and (3) a slight increase in climbing rate. A calculated index of change declined with distance from the source, suggesting zero reaction beyond approximately 1 km. These results revive existing ideas of using light beams on aircraft to prevent bird strikes and provide arguments against the increasing use of light beams for advertising purposes.

Journal Article↗
PubMed1993

The duration of speed reductions attributable to radar detectors.

The duration of speed reductions attributable to radar detector use was observed. When the entire traffic stream was exposed to police radar, the proportion of vehicles traveling more than 10 mph over the speed limit dropped initially from 42% to 28%, but by one mile after exposure, this percentage had already increased to 38%. When speeding vehicles with radar detectors (about 45% of all speeding vehicles) were exposed to police radar, speeds dropped by approximately 15%, but by one mile after exposure, nearly half of the reduction was recovered. These findings indicate that radar detector users slow only briefly when alerted to police radar and that radar detectors are use primarily to avoid speed limit enforcement.

Automobile Driving↗
PubMed2006

Validation of a microwave radar system for the monitoring of locomotor activity in mice.

BACKGROUND: The general or spontaneous motor activity of animals is a useful parameter in chronobiology. Modified motion detectors can be used to monitor locomotor activity rhythms. We modified a commercial microwave-based detection device and validated the device by recording circadian and ultradian rhythms. METHODS: Movements were detected by microwave radar based on the Doppler effect. The equipment was designed to detect and record simultaneously 12 animals in separate cages. Radars were positioned at the bottom of aluminium bulkheads. Animal cages were positioned above the bulkheads. The radars were connected to a computer through a digital I/O board. RESULTS: The apparatus was evaluated by several tests. The first test showed the ability of the apparatus to detect the exact frequency of the standard moving object. The second test demonstrated the stability over time of the sensitivity of the radars. The third was performed by simultaneous observations of video-recording of a mouse and radar signals. We found that the radars are particularly sensitive to activities that involve a displacement of the whole body, as compared to movement of only a part of the body. In the fourth test, we recorded the locomotor activity of Balb/c mice. The results were in agreement with published studies. CONCLUSION: Radar detectors can provide automatic monitoring of an animal's locomotor activity in its home cage without perturbing the pattern of its normal behaviour or initiating the spurt of exploration occasioned by transfer to a novel environment. Recording inside breeding cages enables long-term studies with uninterrupted monitoring. The use of electromagnetic waves allows contactless detection and freedom from interference of external stimuli.

Journal Article↗
PubMed2000

Doppler radar detection of exceptional mass-migration of aphids into Finland.

Our objective was to detect mass migrations of insects of economic significance by insect traps and a Doppler weather radar. Migrants were sampled by suction traps, tow nets and light traps in the Helsinki region. We used radar to observe the migrating insects, and trajectories to backtrack mass migrations of aphids (Homoptera, Aphididae) in spring 1988. The aphid migrations were clearly observed in trap catches and by radar. The first migration, mainly involving Euceraphis betulae, occurred on 18 May and was tracked back to northern Poland. The second migration, mainly of Rhopalosiphum padi (a serious pest of small-grain cereals), occurred 3 days later and was tracked back to a large area covering Latvia and western Russia south of St Petersburg. The third migration included both E. betulae and R. padi, and took place on 30 May. It originated from Estonia. Neither trap nor radar data provide exact quantitative information on migrations. Trapping efficiency depends strongly on wind speed and insect size. Radar echo intensity is very strongly related to the sizes of insects in the large volume of air measured, and the sizes are not known accurately. Weather data, especially temperature, can be used in predicting the development of aphids, and air-parcel trajectories in estimating the source areas of migrants. These methods for forecasting aphid migrations, combined with radar observations, are useful for warning purposes and to intensify insect trapping. This would contribute to more efficient agricultural pest management.

Agriculture↗
PubMed2001

A what-and-where fusion neural network for recognition and tracking of multiple radar emitters.

A neural network recognition and tracking system is proposed for classification of radar pulses in autonomous Electronic Support Measure systems. Radar type information is considered with position-specific information from active emitters in a scene. Type-specific parameters of the input pulse stream are fed to a neural network classifier trained on samples of data collected in the field. Meanwhile, a clustering algorithm is used to separate pulses from different emitters according to position-specific parameters of the input pulse stream. Classifier responses corresponding to different emitters are separated into tracks, or trajectories, one per active emitter, allowing for more accurate identification of radar types based on multiple views of emitter data along each emitter trajectory. Such a What-and-Where fusion strategy is motivated by a similar subdivision of labor in the brain. The fuzzy ARTMAP neural network is used to classify streams of pulses according to radar type using their functional parameters. Simulation results obtained with a radar pulse data set indicate that fuzzy ARTMAP compares favorably to several other approaches when performance is measured in terms of accuracy and computational complexity. Incorporation into fuzzy ARTMAP of negative match tracking (from ARTMAP-IC) facilitated convergence during training with this data set. Other modifications improved classification of data that include missing input pattern components and missing training classes. Fuzzy ARTMAP was combined with a bank of Kalman filters to group pulses transmitted from different emitters based on their position-specific parameters, and with a module to accumulate evidence from fuzzy ARTMAP responses corresponding to the track defined for each emitter. Simulation results demonstrate that the system provides a high level of performance on complex, incomplete and overlapping radar data.

Algorithms↗
PubMedDate not supplied

Microwave emissions from police radar.

This study evaluated police officers' exposures to microwaves emitted by traffic radar units. Exposure measurements were taken at approximated ocular and testicular levels of officers seated in patrol vehicles. Comparisons were made of the radar manufacturers' published maximum power density specifications and actual measured power densities taken at the antenna faces of those units. Four speed-enforcement agencies and one transportation research institute provided 54 radar units for evaluation; 17 different models, encompassing 4 frequency bands and 3 antenna configurations, were included. Four of the 986 measurements taken exceeded the 5 mW/cm2 limit accepted by the International Radiation Protection Association and the National Council on Radiation Protection and Measurement, though none exceeded the American Conference of Governmental Industrial Hygienists, American National Standards Institute, Institute of Electrical and Electronic Engineers, or Occupational Safety and Health Administration standard of 10 mW/cm2. The four high measurements were maximum power density readings taken directly in front of the radar. Of the 812 measurements taken at the officers' seated ocular and testicular positions, none exceeded 0.04 mW/cm2; the highest of these (0.034 mW/cm2) was less than 1% of the most conservative current safety standards. High exposures in the limited region directly in front of the radar aperture are easily avoided with proper training. Results of this study indicate that police officer exposure to microwave radiation is apparently minimal. However, because of uncertainty in the medical and scientific communities concerning nonionizing radiation, it is recommended that law enforcement agencies implement a policy of prudent avoidance, including purchasing units with the lowest published maximum power densities, purchasing dash/rear deck-mounted units with antennae mounted outside the patrol vehicle, and training police officers to use the "stand-by" mode when not actually using radar.

Eye↗
PubMed2005

Online clustering algorithms for radar emitter classification.

Radar emitter classification is a special application of data clustering for classifying unknown radar emitters from received radar pulse samples. The main challenges of this task are the high dimensionality of radar pulse samples, small sample group size, and closely located radar pulse clusters. In this paper, two new online clustering algorithms are developed for radar emitter classification: One is model-based using the Minimum Description Length (MDL) criterion and the other is based on competitive learning. Computational complexity is analyzed for each algorithm and then compared. Simulation results show the superior performance of the model-based algorithm over competitive learning in terms of better classification accuracy, flexibility, and stability.

Algorithms↗
PubMed2005

Comparison of radar and raingauge measurements during heavy rainfall.

Five heavy small-scale rainfall events in North Rhine-Westphalia (Germany) were investigated with radar and raingauge data. Special attention was paid to quality check and adjustment of radar data. Attenuation effects could be observed on both, C-Band and on X-Band radar. Adjustment of radar data to raingauge values turned out to be very difficult in the vicinity of heavy local rain cells. For the five affected regions the precipitation was quantified in the form of areal time series and cumulated radar images. As further result of this project, the spatial extent of the precipitation fields was identified and compared with radar and raingauge data.

Environmental Monitoring↗
PubMed1989

[Serum vitamin A levels of radar operators and effects of supplementary vitamin A].

This paper reports serum vitamin A (VA) content of 28 radar operators, and the effects of supplementation VA were studied by means of observing change of serum VA level and objective dark adaptation time. The results indicated, with respect to serum VA content, 14.3% of radar operators had a deficient level (less than 10 micrograms%), whereas 57.2% of radar operators had a low level (less than 20 micrograms%). There were 39.3% of radar operators who had a low level on nineteenth day and 92.9% of radar operators who had a acceptable value on twenty-eighth day after oral VA supplementation VA of 3,000 IU, suggesting that supplementation VA of 3,000 IU to radar operators with VA malnutrition for about one month is necessary. A certain correlation between serum VA level and objective dark adaptation time was also observed.

Adult↗
PubMed2005

The Research on Adverse Drug Events and Reports (RADAR) project.

CONTEXT: In 1998, a multidisciplinary team of investigators initiated RADAR (Research on Adverse Drug events And Reports), a clinically based postmarketing surveillance program that systematically investigates and disseminates information describing serious and previously unrecognized adverse drug and device reactions (ADRs). OBJECTIVE: To describe the structure, operations, and preliminary findings from the RADAR project and related dissemination efforts by pharmaceutical suppliers and the US Food and Drug Administration (FDA). DESIGN: After identifying a serious and unexpected clinical event suitable for further investigation, RADAR collaborators postulated clinical hypotheses and derived case series and incidence estimates from physician queries, published and unpublished clinical trials, published case reports, FDA databases, and manufacturer sales figures. RESULTS: RADAR investigators identified 16 types of serious ADRs among 1699 patients, of whom 169 (10%) died as a result of the reaction. Initial cases were identified by 7 RADAR investigators, 4 collaborating physicians, 2 attorneys, and by reviewing 3 published reports. Additional sources included queries of occupational health programs and medical directors of interventional cardiology laboratories (3 types of ADRs), published manuscripts and clinical trials (11 types of ADRs), review of medical records at a RADAR site (2 types of ADRs), unpublished clinical trial reports (3 types of ADRs), and reports from attorneys, family members, or patients (4 types of ADRs). Incidence estimates, ranging from 0.4% to 33%, were derived from 5 clinical trial reports, 2 physician queries, and 2 observational databases. Laboratory support for hypotheses included identification of 3 neutralizing antibodies and 3 histopathological findings. ADR reports were disseminated as 8 revised package inserts, 7 "dear doctor" letters, and 9 peer-reviewed articles. CONCLUSION: A new, clinically based, hypothesis-driven approach to postmarketing surveillance may supplement existing regulatory surveillance systems and improve patient safety.

Adverse Drug Reaction Reporting Systems↗
PubMed2002

Radar is required for the establishment of vascular integrity in the zebrafish.

The precise assembly of an integrated network of blood vessels is essential for the survival of vertebrate embryos. However, the processes by which primitive endothelial cells form mature vessels capable of supplying oxygen and nutrients to developing tissues remain incompletely understood. Here, we propose a role for Radar, one of the zebrafish orthologues of gdf6, in establishing integrity of the trunk vasculature in zebrafish embryos. We show that radar expression is appropriately placed, both spatially and temporally, to perform such a role. Transcripts for radar are detected in the hypochord and the primitive gut endoderm. These tissues intimately flank developing axial vessels in the trunk and have been previously implicated in the regulation of vascular development. Morpholino-based targeted gene knock-down has generated a Radar-specific loss-of-function zebrafish model. These embryos display normal initiation of vascular patterning and commencement of circulation. However, by day 2 of development, the integrity of the axial vasculature is compromised with hemorrhages and circulation short-circuits throughout the developing trunk. We show that this aberrant vascular development is specific to a reduction of the radar gene product. These results suggest that Radar is involved in a signaling pathway required for establishing the integrity of the axial vessels during zebrafish development.

Animals↗
PubMed2000

The ventralizing activity of Radar, a maternally expressed bone morphogenetic protein, reveals complex bone morphogenetic protein interactions controlling dorso-ventral patterning in zebrafish.

In Xenopus and zebrafish, BMP2, 4 and 7 have been implicated, after the onset of zygotic expression, in inducing and maintaining ventro-lateral cell fate during early development. We provide evidence here that a maternally expressed bone morphogenetic protein (BMP), Radar, may control early ventral specification in zebrafish. We show that Radar ventralizes zebrafish embryos and induces the early expression of bmp2b and bmp4. The analysis of Radar overexpression in both swirl/bmp2b mutants and embryos expressing truncated BMP receptors shows that Radar-induced ventralization is dependent on functional BMP2/4 pathways, and may initially rely on an Alk6-related signaling pathway. Finally, we show that while radar-injected swirl embryos still exhibit a strongly dorsalized phenotype, the overexpression of Radar into swirl/bmp2b mutant embryos restores ventral marker expression, including bmp4 expression. Our results suggest that a complex regulation of different BMP pathways controls dorso-ventral (DV) patterning from early cleavage stages until somitogenesis.

Alleles↗