When was the non directional beacon invented

This was not especially new technology. However as the airborne equipment consisted of two loops of wire about five feet tall, wound at 90 degrees to each other and mounted on a turntable free to rotate inside the rear fuselage it was heavy and very cumbersome.

There seems to have been only one robust trial of RDF equipment, in which an aeroplane was flown from Biggin Hill to Paris without sight of the ground, then back the next day.

On the strength of these flights and some related work conducted at Andover the US Army Air Service ordered sets for use in their bombers, however the RAF remained unconvinced.

A few other navigation systems were tested around the same time, but these fixed the aerials inside the wing and required the pilot to turn the aircraft towards the station to get a bearing, and then home in on it. Such manoeuvres may be useful if trying to return to base, but they did not help in hitting a target, and so as an aid to tactical navigation they did not catch on. Technical publications published in and explained how both systems worked, complete with photographs and wiring diagrams so it was hardly considered to be secret, but by it appears that the entire idea had been shelved.

A few direction finding sets may have been floating about the squadrons until the mid s, but there does not seem to have been a standard fit, nor any formalised training programme. Individual squadrons might install the equipment for special jobs, such as a long transit flight, and then remove it when it was felt it was no longer needed. Photographs of RAF aircraft taken during this period very rarely show RDF aerials, and the flying manuals never mention it.

Yet there was a desperate operational need for electronic navigation equipment. During a two year period in the s there were a total of forced landings of Bomber Command aircraft due to the aircrew getting lost 2. Four of the aircraft crashed and were written off, killing three crew and injuring several others, the other two aircraft made forced landings and suffered fairly minor damage.

Shortly afterwards a Navigation Officer at HQ 3 Group, Squadron Leader Ogilvy-Forbes, who had some experience of trans-continental navigation in Canada, persuaded the authorities to re-consider the use of airborne direction finding. In time a fresh set of trials at Farnborough demonstrated — somewhat predictably — that the loss of speed was in the order of 1 knot, and not 11, and it was decided shortly afterwards to fit RDF loop aerials to all new Wellington bombers and train observers in their use.

Nevertheless, as we mentioned in podcast four , bomber crews during the early part of the war proved unable to plot accurate radio bearings from ground stations, and a study showed that fewer than one in three aircraft were dropping their bombs within 75 square miles of the target 4. If an alternating electrical current is applied to a length of wire then the electrons in the metal are induced to move back and forth. This happens millions or perhaps billions of times per second. The energy in this rapidly reversing current radiates away from the wire and out into the world around it.

We call the piece of wire a transmitting aerial, and the energy that travels outwards we call radio waves. When these radio waves pass over electrons in another piece of wire, perhaps thousands of miles away, the electrons in this second piece of metal move in sympathy and produce a current identical to the one transmitted, albeit at much lower power. This is the receiving aerial. Radio waves travel at the speed of light, which for our purposes is ,, metres per second.

This is , miles per second, or the equivalent of 7. We define radio waves in terms of frequency or wavelength, although in some respects these descriptions are the same.

An alternating current which cycles once per second will produce one wave in that time. This is said to have frequency of 1 Hertz. Doubling the frequency to 2 Hz will halve the wavelength. By changing the frequency or the amplitude the height of the wave it is possible to superimpose information such as an audio or video signal onto the basic radio wave.

In a vacuum these radio waves would continue radiating out, like ripples on a pond, in perpetuity. However in the context of this study the range of these signals can be thought to be limited by two factors. Firstly, as the radio wave passes through the atmosphere the electrons contained within particles of dust or droplets of water absorb some of the energy, and over time the signal weakens.

Secondly, for most frequencies used in communications and navigation the range is limited by line of sight. Apart from a small amount of propagation near the surface of the earth, and the odd occasion when one can deliberately bounce waves off the ionosphere, radio waves travel in a straight line.

Thus the distance that an aircraft can receive a signal is limited by either obstructions near the transmitting aerial such as high mountains or buildings or by the curvature of the Earth. Thus the theoretical maximum range that an aircraft at 22, ft the typical cruise altitude of a Lancaster in can receive a signal from a ground transmitter ft high is nautical miles.

In an NDB was little more than a generator attached to a simple aerial which sent out a low or medium frequency signal in all directions. All air forces used them because they were relatively cheap to produce, easy to maintain and difficult to destroy by aerial bombing. During our period of the war the UK was dotted with such transmitters.

In the main they were not especially high powered because there were only so many frequencies to go round, and it was no use if signals with the same frequency overlapped, but they formed a very convenient lattice by which a crew could get an idea of their position. The American ones were called either Splashers or Bunchers depending on their specific function, and had a range of about 10 to 25 miles or so 5.

The sketch map below shows the beacons and the formation boxes in East Anglia. Aircrews could also use Royal Navy medium frequency transmitters positioned around the coast, or the huge BBC transmitter codenamed Aspidistra at Maresfield in Sussex.

This was used throughout the war to send news broadcasts and coded messages into occupied Europe, and at the time it was the most powerful broadcast transmitter ever constructed; however the accuracy of the bearings gained from it diminished the further the aircraft was from the transmitter, and over enemy occupied Europe options we few and far between.

If they were sufficiently trusting then bomber crews could use the Swiss Beromunster transmitter near Lucerne, or the German civilian radio stations dotted about the Third Reich, but for obvious reasons it would be a brave crew who relied upon them completely. When the loop is in line with the path of the incoming radio wave the difference in phase between that received on each of the two sides induces a current to flow in the aerial.

Alternatively, when the loop is at right angles to the signal both sides receive the same phase of the wave and no current flows. If we view the aerial from above and plot around it the value of the induced current we find a figure of eight shape with two null points or minima where there is no signal, and two less clearly defined high signal maxima. It might sound counterintuitive, but as you can see from the diagram below, it is in fact much more accurate to determine where there is no signal rather than where there is the strongest signal.

As there are two null points in any degree sweep of the aerial it is impossible to determine whether the NDB lies in front of the loop or behind. To resolve this we need a second aerial, one that acts like an aerial mounted on a car, in that it receives signals from all directions. Turns the aircraft so that the station is directly off one of the wingtips.

Flies that heading, timing how long it takes to cross a specific number of NDB bearings. A runway equipped with NDB or VOR or both as the only navigation aid is called a non-precision approach runway; if it is equipped with ILS it is called a precision approach runway. NDBs are most commonly used as markers or "locators" for an instrument landing system ILS approach or standard approach.

Marker beacons on ILS approaches are now being phased out worldwide with DME ranges used instead to delineate the different segments of the approach. This transmitter could operate on kHz to kHz with a power of W. It was used to send the submarine's location to other submarines or aircraft, which were equipped with DF receivers and loop antennas. NDBs typically operate in the frequency range from kHz to kHz although they are allocated frequencies from to kHz and transmit a carrier modulated by either or Hz.

NDBs can also be co-located with a DME in a similar installation for the ILS as the outer marker, only in this case, they function as the inner marker. NDB owners are mostly governmental agencies and airport authorities. NDB radiators are vertically polarised. NDB antennas are usually too short for resonance at the frequency they operate — typically perhaps 20m length compared to a wavelength around m.

Therefore they require a suitable matching network that may consist of an inductor and a capacitor to "tune" the antenna. Vertical NDB antennas may also have a 'top hat', which is an umbrella-like structure designed to add loading at the end and improve its radiating efficiency. Usually a ground plane or counterpoise is connected underneath the antenna. The pilot uses their ADF receiver to hear instructions from the Tower.

If an NDB has a problem, e. While pilots study these effects during initial training, trying to compensate for them in flight is very difficult; instead, pilots generally simply choose a heading that seems to average out any fluctuations. Besides their use in aircraft navigation, NDBs are also popular with long-distance radio enthusiasts "DXers". Because NDBs are generally low-power usually 25 watts, some can be up to 5 kW , they normally cannot be heard over long distances, but favorable conditions in the ionosphere can allow NDB signals to travel much farther than normal.

Because of this, radio DXers interested in picking up distant signals enjoy listening to faraway NDBs. Also, since the band allocated to NDBs is free of broadcast stations and their associated interference, and because most NDBs do little more than transmit their Morse Code callsign, they are very easy to identify, making NDB monitoring an active niche within the DXing hobby. In Europe, there is a longwave broadcasting band from to kHz, so the European NDB band is from kHz to kHz with a gap between and kHz because kHz was the international maritime distress emergency frequency.

The beacons that are between kHz and kHz can sometimes be heard on AM radios that can tune below the beginning of the AM broadcast band. Some beacons can also be heard on kHz, although from the adjacent frequencies such as "LYQ" at kHz in Manchester, Tennessee but for the most part, reception of NDBs requires a radio receiver that can receive frequencies below kHz the longwave band.

Most so-called "shortwave" radios also include mediumwave and longwave, and they can usually receive all frequencies from kHz to 30 MHz, which makes them ideal for listening to NDBs. Whilst this type of receiver is adequate for reception of local beacons, specialized techniques receiver preselectors, noise limiters and filters are required for the reception of very weak signals from remote beacons. The best time to hear NDBs that are very far away i. Reception of NDBs is also usually best during the fall and winter because during the spring and summer, there is more atmospheric noise on the LF and MF bands.

Open navigation menu. Close suggestions Search Search. User Settings. We herein conduct studies to validate the Surface Beacon transponder in terms of stability, reproducibility, orientation sensitivity, cycle rate dependence, and respiratory waveform tracking accuracy. The Surface Beacon was placed on a Quasar respiratory phantom and positioned at the isocenter with its two arms aligned with the lasers.

Breathing waveforms were simulated, and the motion of the transponder was tracked. The mean and standard deviation SD of the amplitudes were calculated. Linear least-squares fitting was performed to access the possible amplitude drift over the breathing cycles. Reproducibility: similar setting to stability and drift analysis, and the phantom generated cycles of the sinusoidal waveform per run.

The Calypso system's was re-setup for each run. Beacon orientation sensitivity: the Calypso tracks sinusoidal phantom motion with a defined angular offset of the beacon to assess its effect on SD and peak-to-peak amplitude. Rate dependence: sinusoidal motion was generated at cycle rates of 1 Hz,.

Peak-to-peak displacement and SDs were assessed. Respiratory waveform tracking accuracy: the phantom reproduced recorded breathing cycles by volunteers and patients were tracked by the Calypso system. Deviation in tracking position from produced waveform was used to calculate SD throughout entire breathing cycle. No clinically significant drift was detected with drift measured as 5.

No clinically significant drift was detected with drift. MDR1 multidrug resistance gene mRNA expression is a promising biomarker for the prediction of doxorubicin resistance in clinic.

However, the traditional technical process in clinic is complicated and cannot perform the real-time detection mRNA in living single cells. Then, optimized MDR1 molecular beacons were characterized by transmission electron microscope, UV-vis and fluorescence spectroscopies.

Dark field microscope was used to investigate the cellular uptake of hDAuNP beacon assisted with ultrasound. In summary, optimized MDR1 molecular beacon designed in this study is a reliable strategy for detection MDR1 mRNA expression in living tumor cells, and will be a promising strategy for in guiding patient treatment and management in individualized medication.

Final Report. This study examined six Beacon centers, which are community centers located in public school buildings that offer a range of activities and services to participants of all ages, before and after school, in the evenings, and on weekends. Individual Beacons are managed by community-based organizations. The study examined how the Beacons provided…. Summary Report. In this paper, the design of a beacon transmitter that will be flown as a hosted payload on a geostationary satellite to enable propagation experiments at Q-band GHz frequencies is presented.

The beacon uses a phased locked loop stabilized dielectric resonator oscillator and a solid-state power amplifier to achieve the desired output power. The satellite beacon antenna is configured as an offset-fed cut-paraboloidal reflector. Quick acquisition and recognition method for the beacon in deep space optical communications.

In deep space optical communications, it is very difficult to acquire the beacon given the long communication distance. Acquisition efficiency is essential for establishing and holding the optical communication link. Here we proposed a quick acquisition and recognition method for the beacon in deep optical communications based on the characteristics of the deep optical link. To identify the beacon from the background light efficiently, we utilized the maximum similarity between the collecting image and the reference image for accurate recognition and acquisition of the beacon in the area of uncertainty.

First, the collecting image and the reference image were processed by Fourier-Mellin. Second, image sampling and image matching were applied for the accurate positioning of the beacon. Finally, the field programmable gate array FPGA -based system was used to verify and realize this method. The experimental results showed that the acquisition time for the beacon was as fast as 8. Future application of this method in the system design of deep optical communication will be beneficial.

The relationship between RNA expression and cell function can often be difficult to decipher due to the presence of both temporal and sub-cellular processing of RNA. These intricacies of RNA regulation can often be overlooked when only acquiring global measurements of RNA expression.

This has led to development of several tools that allow for the real-time imaging of individual engineered RNA transcripts in living cells. Binding of RBMBs to the target RNA resulted in discrete bright fluorescent spots, representing individual transcripts, that could be imaged in real-time.

Since RBMBs are a synthetic probe, the use of photostable, bright, and red-shifted fluorophores led to a high signal-to-background. RNA motion was readily characterized by both mean squared displacement and moment scaling spectrum analyses.

These analyses revealed clear examples of directed , Brownian, and subdiffusive movements. The open-source software toolkit for the software defined radio, GNU Radio, is utilized to realize the basic function of the receiver and perform fast signal processing. The first experiment was successful as results from GRBR showed very good agreement to those from the co-located analog beacon receiver. Energy harvester-integrated wireless devices are attractive for generating semi-permanent power from wasted energy in industrial environments.

The energy-harvesting wireless devices may have difficulty in their communication with access points due to insufficient power supply for beacon recognition during network initialization.

In this manuscript, we propose a novel method of beacon recognition based on wake-up control to reduce instantaneous power consumption in the initialization procedure. The proposed method applies a moving window for the periodic wake-up of the wireless devices. For unsynchronized wireless devices, beacons are always located in the same positions within each beacon interval even though the starting offsets are unknown. Using these characteristics, the moving window checks the existence of the beacon associated withspecified resources in a beacon interval, checks again for neighboring resources at the next beacon interval, and so on.

This method can reduce instantaneous power and generates a surplus of charging time. Thus, the proposed method alleviates the problems of power insufficiency in the network initialization. The feasibility of the proposed method is evaluated using computer simulations of power shortage in various energy-harvesting conditions.

Autonomous navigation using lunar beacons. The concept of using lunar beacon signal transmission for on-board navigation for earth satellites and near-earth spacecraft is described. The system would require powerful transmitters on the earth-side of the moon's surface and black box receivers with antennae and microprocessors placed on board spacecraft for autonomous navigation.

Spacecraft navigation requires three position and three velocity elements to establish location coordinates. Two beacons could be soft-landed on the lunar surface at the limits of allowable separation and each would transmit a wide-beam signal with cones reaching GEO heights and be strong enough to be received by small antennae in near-earth orbit. To complement national and state-level HITECH Act programs, 17 Beacon communities were funded to fuel community-wide use of health information technology to improve quality.

Health centers in Beacon communities received supplemental funding. This article explores the association between participation in the Beacon program and the adoption of electronic health records. Using the Uniform Data System, trends in health information technology adoption among health centers located within and outside of Beacon communities were explored using differences in mean t tests and multivariate logistic regression.

Electronic health record adoption was widespread and rapidly growing in all health centers, especially quality improvement functionalities: structured data capture, order and results management, and clinical decision support. Adoption lagged for functionalities supporting patient engagement, performance measurement, care coordination, and public health.

The use of advanced functionalities such as care coordination grew faster in Beacon health centers, and Beacon health centers had 1. Three factors likely underlie these findings: technical assistance, community-wide activation supporting health information exchange, and the layering of financial incentives. Additional technical assistance and community-wide activation is needed to support the use of functionalities that are currently lagging. Crescent Evaluation : appendix F : state-line beacon project : user case studies.

A roadside transmit beacon would be located on the state lines a Pedestrian and motorists' actions at pedestrian hybrid beacon sites: findings from a pilot study. This paper focuses on an analysis of pedestrian and motorists' actions at sites with pedestrian hybrid beacons and assesses their effectiveness in improving the safety of pedestrians. Descriptive and statistical analyses one-tail two-sample T-test and two-proportion Z-test were conducted using field data collected during morning and evening peak hours at three study sites in the city of Charlotte, NC, before and after the installation of pedestrian hybrid beacons.

Further, an analysis was conducted to assess the change in pedestrian and motorists' actions over time before the installation; 1 month, 3 months, 6 months, and 12 months after the installation. Results showed an increase in average traffic speed at one of the pedestrian hybrid beacon sites while no specific trends were observed at the other two pedestrian hybrid beacon sites.

A decrease in the number of motorists not yielding to pedestrians, pedestrians trapped in the middle of the street, and pedestrian-vehicle conflicts were observed at all the three pedestrian hybrid beacon sites.

The installation of pedestrian hybrid beacons did not have a negative effect on pedestrian actions at two out of the three sites. Improvements seem to be relatively more consistent 3 months after the installation of the pedestrian hybrid beacon. Many applications in wireless sensor networks WSNs require the energy efficiency and scalability.

Although IEEE Recently, various algorithms to resolve this problem are proposed. Simulation results show that by using the proposed algorithm, the energy efficiency and the throughput of whole network can be significantly improved.

EBBS-AB is also more effective for the network performance when the nodes are uniformly deployed on the sensor field rather than the case of random topologies. Dual-band beacon experiment over Southeast Asia for ionospheric irregularity analysis.

Watthanasangmechai, K. An experiment of dual-band beacon over Southeast Asia was started in March in order to capture and analyze ionospheric irregularities in equatorial region. The distances between the stations reach more than km. To capture ionospheric irregularities, the absolute TEC estimation technique was developed. The two-station method Leitinger et al. However, the distances between the stations directly affect on the robustness of the technique. In Southeast Asia, the observational network is too sparse to attain a benefit of the classic two-station method.

Moreover, the least-squares approch used in the two-station method tries too much to adjust the small scales of the TEC distribution which are the local minima. The key of the proposed technique is to utilize the brute-force technique with weighting function to find the TEC offset set that yields a global minimum of RMSE in whole parameter space. In additions, the km-scale fluctuations from an Equatorial Spread F ESF are captured at night time in equinox seasons. The plausible linkage of the meridional wind with triggering of ESF is under invatigating and will be presented.

The proposed method is successful to estimate the latitudinal TEC distribution from dual. Detection of DNA damage by using hairpin molecular beacon probes and graphene oxide. A hairpin molecular beacon tagged with carboxyfluorescein in combination with graphene oxide as a quencher reagent was used to detect the DNA damage by chemical reagents.

The fluorescence of molecular beacon was quenched sharply by graphene oxide; while in the presence of its complementary DNA the quenching efficiency decreased because their hybridization prevented the strong adsorbability of molecular beacon on graphene oxide.

If the complementary DNA was damaged by a chemical reagent and could not form intact duplex structure with molecular beacon , more molecular beacon would adsorb on graphene oxide increasing the quenching efficiency.

Thus, damaged DNA could be detected based on different quenching efficiencies afforded by damaged and intact complementary DNA. The damage effects of chlorpyrifos-methyl and three metabolites of styrene such as mandelieaeids, phenylglyoxylieaeids and epoxystyrene on DNA were studied as models.

The method for detection of DNA damage was reliable, rapid and simple compared to the biological methods. In this paper, the design of a beacon transmitter that will be flown as a hosted payload on a geostationary satellite to enable propagation experiments at Q-band 37 to 41 GHz frequencies is presented.

The satellite beacon antenna is configured as an offset-fed cutparaboloidal reflector. Retinoblastoma RB is the most common primary intraocular malignancy of infancy. An alternative RB treatment protocol is proposed and tested.

Cells with and without MDMX high-expression are incubated with the beacon and then irradiated with a laser. The fluorescence and reactive oxygen species are detected in solution to verify the specific activation of PPa by the perfectly matched DNA targets. The cell viabilities are evaluated with CCK-8 and flow cytometry assay. The data suggest that the designed beacon may provide a potential alternative for RB therapy and secures the ground for future investigation.

DNA aptamer beacon assay for C-telopeptide and handheld fluorometer to monitor bone resorption. One aptamer sequence and its reverse complement dominated the aptamer pool Secondary structures of these aptamers were examined for potential binding pockets.

Three-dimensional computer models which analyzed docking topologies and binding energies were in agreement with empirical fluorescence experiments used to select one candidate loop for beacon assay development. All loop structures from the aptamer finalists were end-labeled with TYE and Iowa Black quencher for comparison of beacon fluorescence levels as a function of CTx concentration. The prototype assay was shown to detect CTx peptide from human urine after creatinine and urea were removed by size-exclusion chromatography to prevent nonspecific denaturing of the aptamer beacon.

This work demonstrates the potential of aptamer beacons to be utilized for rapid and sensitive bone health monitoring in a handheld or point-of-care format. What Happened to the Beacon Schools? Policy Reform and Educational Equity.

This paper considers the impact of the Beacon schools initiative on the social and academic characteristics of secondary schools in England. The Beacon schools programme ran from to and epitomised the then Labour government's focus on school improvement through diversity, collaboration and partnership. This paper looks at variation in…. Power sources for search and rescue MHz beacons.

The results of a study directed at the selection of a commercially available, safe, low cost, light weight and long storage life battery for search and rescue Sarsat MHz emergency beacons are presented. In the course of this work, five electrochemical systems lithium-manganese dioxide, lithium-carbon monofluoride, lithium-silver vanadium oxide, alkaline cells, and cadmium-mercuric oxide were selected for limited experimental studies to determine their suitability for this application.

Two safe, commercially available batteries lithium-manganese dioxide and lithium-carbon monofluoride which meet the near term requirements and several alternatives for the long term were identified.

Guth, David A. Veering outside of crosswalks is a common problem experienced by individuals who are blind. One technology found to be effective for reducing this veer when other guidance cues are absent is audible beaconing. However, veering in general and veering from crosswalks in particular have been studied primarily on smooth, flat walking surfaces such as clear pavement. This experiment compared veering on clear pavement with veering on snow-covered pavement, with and without audible beaconing.

Eleven blind participants traveling with long canes attempted to walk a straight path for 72 ft Beaconing substantially reduced veering at 36 ft Walking on snow was not found to affect veering but did increase the number of steps taken. The findings suggest that in snowy and clear conditions alike, audible beaconing is an effective wayfinding tool for intersections equipped with accessible pedestrian signals.

Preliminary performance analysis of an interplanetary navigation system using asteroid based beacons. A futuristic interplanetary navigation system using transmitters placed on selected asteroids is introduced. This network of space beacons is seen as a needed alternative to the overly burdened Deep Space Network.

Covariance analyses on the potential performance of these space beacons located on a candidate constellation of eight real asteroids are initiated. Simplified analytic calculations are performed to determine limiting accuracies attainable with the network for geometric positioning.

More sophisticated computer simulations are also performed to determine potential accuracies using long arcs of range and Doppler data from the beacons. The results from these computations show promise for this navigation system. In this study, we synthesized a simple but efficient quencher-free molecular beacon tethering 7-hydroxycoumarin on D-threoninol based on its pK a change. The pK a of 7-hydroxycoumarin in a single strand was determined as 8. This large pK a shift more than 1. Because 7-hydroxycoumarin quenches its fluorescence upon protonation, the emission intensity of the duplex at pH 8.

We applied this quenching mechanism to the preparation of a quencher-free molecular beacon by introducing the dye into the middle of the stem part. In the absence of the target, the stem region formed a duplex and fluorescence was quenched. However, when the target was added, the molecular beacon opened and the dye was deprotonated.

As a result, the emission intensity of the molecular beacon with the target was 10 times higher than that without the target. Accordingly, a quencher-free molecular beacon utilizing the pK a change was successfully developed. In this paper, we present a method for recognizing algorithms from students programming submissions coded in Java. The method is based on the concept of "programming schemas" and " beacons ".

Schemas are high-level programming knowledge with detailed knowledge abstracted out, and beacons are statements that imply specific…. During summer , the British government's Department for Education and Employment recognized 74 schools as model " beacons of excellence.

Visual detection of multidrug resistance gene in living cell using the molecular beacon imaging. A major problem in cancer treatment is the development of resistance to chemotherapeutic agents in tumor cells. Detection of effective prognostic biomarkers and targets are of crucial importance to the management of individualized therapies.

However, quantitative analysis of the drug resistance gene had been difficult because of technical limitations. In this study, we designed and used a special hairpin deoxyribonucleic acid DNA , which served as a beacon for detecting human drug resistance indicater. The hDAuNP beacons could be taken up by living cells with low inherent cytotoxicity and higher stability. Thus, this approach overcame many of the challenges of previous techniques by creating highly sensitive and effective intracellular probes for monitoring gene expression.

A molecular- beacon -based asymmetric PCR assay for easy visualization of amplicons in the diagnosis of trichomoniasis. The currently available nucleic acid amplification tests NAATs for trichomoniasis are accurate, quick and confirmative with superior sensitivity than traditional culture-based microbiology assays.

However, these assays are associated with problems of carry over contamination, false positive results, requirement of technical expertise for performance and detection of end product. Hence, a diagnostic assay with easy visualization of the amplified product will be profitable.

For easy visualization of the amplified product, molecular- beacon was designed and amplicons were visualized directly using fluorescent handheld dark reader or by Micro-Plate Reader. The beacon -based PCR assay designed in the present study is highly specific as confirmed by competition experiments and extremely sensitive with detection limit of 20fg of genomic DNA pathogens.

The minimum infrastructure requirement and ease to perform the assay makes this method highly useful for resource poor countries for better disease management. Mars approach navigation using Doppler and range measurements to surface beacons and orbiting spacecraft. Approximate analytical models are developed and used to construct an error covariance analysis for investigating the range of orbit determination accuracies which might be achieved for typical Mars approach trajectories.

The results indicate that the orbit determination performance obtained from both Doppler and range data is a strong function of the inclination of the approach trajectory to the Martian equator, for surface beacons , and for orbiters, the inclination relative to the orbital plane.

Large variations in performance were also observed for different approach velocity magnitudes; Doppler data in particular were found to perform poorly in determining the downtrack along the direction of flight component of spacecraft position. In addition, it was found that small spacecraft acceleration modeling errors can induce large errors in the Doppler-derived downtrack position estimate. Impact of beacon wavelength on phase-compensation performance. This study evaluates the effects of beacon -wavelength mismatch on phase-compensation performance.

In general, beacon -wavelength mismatch occurs at the system level because the beacon -illuminator laser BIL and high-energy laser HEL are often at different wavelengths. Such is the case, for example, when using an aperture sharing element to isolate the beam-control sensor suite from the blinding nature of the HEL. To quantify phase-compensation performance, we also model a nominal adaptive-optics AO system. We achieve correction from a Shack-Hartmann wavefront sensor and continuous-face-sheet deformable mirror using a least-squares phase reconstruction algorithm in the Fried geometry and a leaky integrator control law.

This outcome is consistent with past results. Beacons of X-ray Light Animation. This image shows a neutron star -- the core of a star that exploded in a massive supernova. This particular neutron star is known as a pulsar because it sends out rotating beams of X-rays that sweep past Earth like lighthouse beacons. The Hegenberger system, which was adopted by both civil and military aviation authorities, used a series of non-directional radio beacons NDB and marker beacons on the ground, along with a radio-compass and other gyroscopic instruments and radio receivers aboard the aircraft, a Consolidated NY-2 biplane.

They were aligned with the runway centerline. Both had marker beacons which would signal that the airplane was directly overhead. The radio compass aboard the airplane would indicate the direction of the NDB relative to the airplane and lights would illuminate when it passed over the marker beacons. When the airplane was heading directly toward the NDB, the needle pointed to zero.

Captain Hegenberger turned toward the inner NDB from a distance of 50 miles 80 kilometers. He passed over it at a pre-planned altitude. When the lights on the instrument panel came on indicating that he was directly over the inner marker beacon, he turned toward the outer NDB. As he passed over the inner NDB again, he reduced engine power and placed the airplane in a landing attitude and waited for it to touch down on the runway.

This flight was the first solo blind instrument flight, approach and landing. James H. Doolittle had made a blind instrument flight in , but he carried a safety pilot aboard.