Clinical Characteristics and Low Vision Rehabilitation Methods for Partially Sighted School-Age Children

PubMed Central

Özen Tunay, Zuhal; Çalışkan, Deniz; İdil, Aysun; Öztuna, Derya

2016-01-01

Objectives: To determine the clinical features and the distribution of diagnosis in partially sighted school-age children, to report the chosen low vision rehabilitation methods and to emphasize the importance of low vision rehabilitation. Materials and Methods: The study included 150 partially sighted children between the ages of 6 and 18 years. The distribution of diagnosis, accompanying ocular findings, visual acuity of the children both for near and distance with and without low vision devices, and the methods of low vision rehabilitation (for distance and for near) were determined. The demographic characteristics of the children and the parental consanguinity were recorded. Results: The mean age of children was 10.6 years and the median age was 10 years; 88 (58.7%) of them were male and 62 (41.3%) of them were female. According to distribution of diagnoses among the children, the most frequent diagnosis was hereditary fundus dystrophies (36%) followed by cortical visual impairment (18%). The most frequently used rehabilitation methods were: telescopic lenses (91.3%) for distance vision; magnifiers (38.7%) and telemicroscopic systems (26.0%) for near vision. A significant improvement in visual acuity both for distance and near vision were determined with low vision aids. Conclusion: A significant improvement in visual acuity can be achieved both for distance and near vision with low vision rehabilitation in partially sighted school-age children. It is important for ophthalmologists and pediatricians to guide parents and children to low vision rehabilitation. PMID:27800263

Clinical Characteristics and Low Vision Rehabilitation Methods for Partially Sighted School-Age Children.

PubMed

Özen Tunay, Zuhal; Çalışkan, Deniz; İdil, Aysun; Öztuna, Derya

2016-04-01

To determine the clinical features and the distribution of diagnosis in partially sighted school-age children, to report the chosen low vision rehabilitation methods and to emphasize the importance of low vision rehabilitation. The study included 150 partially sighted children between the ages of 6 and 18 years. The distribution of diagnosis, accompanying ocular findings, visual acuity of the children both for near and distance with and without low vision devices, and the methods of low vision rehabilitation (for distance and for near) were determined. The demographic characteristics of the children and the parental consanguinity were recorded. The mean age of children was 10.6 years and the median age was 10 years; 88 (58.7%) of them were male and 62 (41.3%) of them were female. According to distribution of diagnoses among the children, the most frequent diagnosis was hereditary fundus dystrophies (36%) followed by cortical visual impairment (18%). The most frequently used rehabilitation methods were: telescopic lenses (91.3%) for distance vision; magnifiers (38.7%) and telemicroscopic systems (26.0%) for near vision. A significant improvement in visual acuity both for distance and near vision were determined with low vision aids. A significant improvement in visual acuity can be achieved both for distance and near vision with low vision rehabilitation in partially sighted school-age children. It is important for ophthalmologists and pediatricians to guide parents and children to low vision rehabilitation.

KINETIC TOMOGRAPHY. I. A METHOD FOR MAPPING THE MILKY WAY’S INTERSTELLAR MEDIUM IN FOUR DIMENSIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tchernyshyov, Kirill; Peek, J. E. G.

2017-01-01

We have developed a method for deriving the distribution of the Milky Way’s interstellar medium as a function of longitude, latitude, distance, and line-of-sight velocity. This method takes as input maps of reddening as a function of longitude, latitude, distance, and maps of line emission as a function of longitude, latitude, and line-of-sight velocity. We have applied this method to data sets covering much of the Galactic plane. The output of this method correctly reproduces the line-of-sight velocities of high-mass star-forming regions with known distances from Reid et al. and qualitatively agrees with results from the Milky Way kinematics literature.more » These maps will be useful for measuring flows of gas around the Milky Way’s spiral arms and into and out of giant molecular clouds.« less

Reconstructing Seasonal Range Expansion of the Tropical Butterfly, Heliconius charithonia, into Texas Using Historical Records

PubMed Central

Cardoso, Márcio Zikán

2010-01-01

While butterfly responses to climate change are well studied, detailed analyses of the seasonal dynamics of range expansion are few. Therefore, the seasonal range expansion of the butterfly Heliconius charithonia L. (Lepidoptera: Nymphalidae) was analyzed using a database of sightings and collection records dating from 1884 to 1992 from Texas. First and last sightings for each year were noted, and residency time calculated, for each collection locality. To test whether sighting dates were a consequence of distance from source (defined as the southernmost location of permanent residence), the distance between source and other locations was calculated. Additionally, consistent directional change over time of arrival dates was tested in a well-sampled area (San Antonio). Also, correlations between temperature, rainfall, and butterfly distribution were tested to determine whether butterfly sightings were influenced by climate. Both arrival date and residency interval were influenced by distance from source: butterflies arrived later and residency time was shorter at more distant locations. Butterfly occurrence was correlated with temperature but not rainfall. Residency time was also correlated with temperature but not rainfall. Since temperature follows a north-south gradient this may explain the inverse relationship between residency and distance from entry point. No long-term directional change in arrival dates was found in San Antonio. The biological meaning of these findings is discussed suggesting that naturalist notes can be a useful tool in reconstructing spatial dynamics. PMID:20672989

Sighting frequency and relative abundance of bottlenose dolphins (Tursiops truncatus) along the northeast coast of Margarita Island and Los Frailes Archipelago, Venezuela.

PubMed

Oviedo, Lenin; Silva, Noemi

2005-01-01

The study of local cetaceans in Venezuela has a very recent history, and few efforts have been made in the assessment of coastal populations based on field research. The occurrence of whales and dolphins along the northeast coast of Venezuela has been documented through sightings and stranding records. Given the underwater topographical features and the influence of upwelling processes, this area is considered a very productive coastal ecosystem. Our objective was to establish the sighting frequency and relative abundance of bottlenose dolphins in the area. Sighting records were gathered on bottlenose dolphins and other cetacean species occurring along the northeast coast of Margarita Island and Los Frailes Archipelago through direct observation during land-based (6 surveys, 48 hours of observation) and boat-based surveys (24 surveys, 121 hours of observation, 1295 km covered). A sighting frequency was calculated using two methodologies and then compared, considering: 1) a mean effective observation time (4.27 hours), and 2) distance covered with cetacean sightings (1108 kin). A third method is proposed relating a mean effective distance covered with cetacean sightings and expressed as a percentage. The abundance index was calculated using the mean effective observation time. The sighting frequency of Tursiops truncattus in the study area was 3 - 4 sightings per day of 4.27 observation hours, or by 185 kilometers covered. The relative abundance was calculated as 35 dolphins in the study area, so a total population of less than 60 dolphins could inhabit the proposed range. Tursiops truncatus is the dominant species in the northeast coast of Margarita Island and Los Frailes Archipelago with 70% of all the sightings, so this locality could be termed as the distribution range of a possible local population of bottlenose dolphins.

Sequential vs simultaneous encoding of spatial information: a comparison between the blind and the sighted.

PubMed

Ruotolo, Francesco; Ruggiero, Gennaro; Vinciguerra, Michela; Iachini, Tina

2012-02-01

The aim of this research is to assess whether the crucial factor in determining the characteristics of blind people's spatial mental images is concerned with the visual impairment per se or the processing style that the dominant perceptual modalities used to acquire spatial information impose, i.e. simultaneous (vision) vs sequential (kinaesthesis). Participants were asked to learn six positions in a large parking area via movement alone (congenitally blind, adventitiously blind, blindfolded sighted) or with vision plus movement (simultaneous sighted, sequential sighted), and then to mentally scan between positions in the path. The crucial manipulation concerned the sequential sighted group. Their visual exploration was made sequential by putting visual obstacles within the pathway in such a way that they could not see simultaneously the positions along the pathway. The results revealed a significant time/distance linear relation in all tested groups. However, the linear component was lower in sequential sighted and blind participants, especially congenital. Sequential sighted and congenitally blind participants showed an almost overlapping performance. Differences between groups became evident when mentally scanning farther distances (more than 5m). This threshold effect could be revealing of processing limitations due to the need of integrating and updating spatial information. Overall, the results suggest that the characteristics of the processing style rather than the visual impairment per se affect blind people's spatial mental images. Copyright © 2011 Elsevier B.V. All rights reserved.

Differences in kata performance time and distance from a marker for experienced Shotokan karateka under normal sighted and blindfolded conditions.

PubMed

Layton, Clive; Avenell, Leon

2002-08-01

10 experienced Shotokan karateka were tested on performance time and distance from a marker on the five Heian kata under normal sighted and blind-folded conditions. Whilst each kata's line of movement is different, it is the intention to start and finish at the same location. Analysis showed that despite an average of 16.8 yr. of training, whilst timing was not significantly affected on four of the kata by subjects being deprived of the visual sense, the group's mean change in distance from an original marker was significant for performances on three of the kata.

The Haptic Paradigm in Education: Challenges and Case Studies

ERIC Educational Resources Information Center

Hamza-Lup, Felix G.; Stanescu, Ioana A.

2010-01-01

The process of learning involves interaction with the learning environment through our five senses (sight, hearing, touch, smell, and taste). Until recently, distance education focused only on the first two of those senses, sight and sound. Internet-based learning environments are predominantly visual with auditory components. With the advent of…

Variability in the Length and Frequency of Steps of Sighted and Visually Impaired Walkers

ERIC Educational Resources Information Center

Mason, Sarah J.; Legge, Gordon E.; Kallie, Christopher S.

2005-01-01

The variability of the length and frequency of steps was measured in sighted and visually impaired walkers at three different paces. The variability was low, especially at the preferred pace, and similar for both groups. A model incorporating step counts and step frequency provides good estimates of the distance traveled. Applications to…

Pedestrian Safety in Road Traffic in Poland

NASA Astrophysics Data System (ADS)

Budzynski, Marcin; Jamroz, Kazimierz; Mackun, Tomasz

2017-10-01

Every third road accident in Poland involves a pedestrian as a participant or, most of the time, a casualty. Pedestrian accidents are usually the result of complex situations and the outcome of a number of factors related to driver and pedestrian behaviour and road infrastructure. Safety depends largely on how well the traffic condition is perceived and on visibility in traffic. The paper presents the results of analyses of methodologies for systematic studies of pedestrian behaviour and pedestrian-driver relations. The effects of the location of the site, type of cross-section and other selected parameters on pedestrian and driver behaviour are demonstrated. The analyses showed that pedestrians are most often put at risk by too long pedestrian crossings, vehicles going too fast around pedestrian crossings, lack of proper sight distance and poorly lit or unlit pedestrian crossings. The reason for such defective infrastructure is that planners, designers, contractors and maintenance services are not receiving any support from design, marking and maintenance regulations for pedestrian traffic. In addition, the Road Traffic Law is not restrictive enough when it comes to drivers’ obligations towards pedestrian safety. Polish design regulations allow long pedestrian crossings up to four lanes in one direction or three lanes in two directions irrespective of traffic control and speed limits. Pedestrian crossings should be kept at a maximum of three lanes. There is nothing in the design regulations about the required driver-pedestrian sight distance. Neither does the Road Traffic Law help engineers with that. It is legal to park vehicles within 10 m of a pedestrian crossing which does not guarantee the necessary sight distance. Drivers must be able to see a pedestrian waiting or stepping onto the crossing from a distance that will help them come to a stop safely. It is safer to follow the principle of providing adequate pedestrian sight distance. Recommendations for pedestrian crossing design are also provided.

REGARDING THE LINE-OF-SIGHT BARYONIC ACOUSTIC FEATURE IN THE SLOAN DIGITAL SKY SURVEY AND BARYON OSCILLATION SPECTROSCOPIC SURVEY LUMINOUS RED GALAXY SAMPLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kazin, Eyal A.; Blanton, Michael R.; Scoccimarro, Roman

2010-08-20

We analyze the line-of-sight baryonic acoustic feature in the two-point correlation function {xi} of the Sloan Digital Sky Survey luminous red galaxy (LRG) sample (0.16 < z < 0.47). By defining a narrow line-of-sight region, r{sub p} < 5.5 h {sup -1} Mpc, where r{sub p} is the transverse separation component, we measure a strong excess of clustering at {approx}110 h {sup -1} Mpc, as previously reported in the literature. We also test these results in an alternative coordinate system, by defining the line of sight as {theta} < 3{sup 0}, where {theta} is the opening angle. This clustering excessmore » appears much stronger than the feature in the better-measured monopole. A fiducial {Lambda}CDM nonlinear model in redshift space predicts a much weaker signature. We use realistic mock catalogs to model the expected signal and noise. We find that the line-of-sight measurements can be explained well by our mocks as well as by a featureless {xi} = 0. We conclude that there is no convincing evidence that the strong clustering measurement is the line-of-sight baryonic acoustic feature. We also evaluate how detectable such a signal would be in the upcoming Baryon Oscillation Spectroscopic Survey (BOSS) LRG volume. Mock LRG catalogs (z < 0.6) suggest that (1) the narrow line-of-sight cylinder and cone defined above probably will not reveal a detectable acoustic feature in BOSS; (2) a clustering measurement as high as that in the current sample can be ruled out (or confirmed) at a high confidence level using a BOSS-sized data set; (3) an analysis with wider angular cuts, which provide better signal-to-noise ratios, can nevertheless be used to compare line-of-sight and transverse distances, and thereby constrain the expansion rate H(z) and diameter distance D{sub A}(z).« less

Mapping the Heiles Supershell GSH 90-28-17

NASA Astrophysics Data System (ADS)

Montgomery, Sharon Lynn; Beckey, Jacob Lucas; Welsh, Barry; Kuehne, John W.

2017-01-01

Large-diameter shells of neutral gas called superbubbles were first detected by the 21-cm radio surveys of Heiles (1979,1984) and are likely formed by stellar winds and supernova explosions. Some of these interstellar voids (including GSH 90-28-17) span more than 10 degrees of the sky. However, only a few studies have been able to identify the power source of a particular Heiles shell. The problem is that HI 21cm emission can arise at all distances along a given sight-line, so while we many know the speed at which neutral gas is moving, we do not know the distance of this gas. Indeed, a given line of sight may penetrate multiple shell walls making the interpretation of the radio data very challenging.Here we report on an absorption study of the interstellar absorption lines of NaI, CaII, CaI, CH and CH+ detected towards nine stellar continuum sources with sight-line distances increasing from 90 pc to >1kpc in the direction of the supershell GSH 90-28-17. Our observations, recorded with the Sandiford echelle spectrograph on the 2.1m telescope at the McDonald Observatory (Texas) in August 2016, reveal gas components with velocities between -10 and -50 km/s orginating from distances >400 pc that we can associate with the expansion of the GSH 90-28-17 shell.

A Dust-scattering Halo of 4U 1630–47 Observed with Chandra and Swift: New Constraints on the Source Distance

NASA Astrophysics Data System (ADS)

Kalemci, E.; Maccarone, T. J.; Tomsick, J. A.

2018-06-01

We have observed the Galactic black hole transient 4U 1630‑47 during the decay of its 2016 outburst with Chandra and Swift to investigate the properties of the dust-scattering halo created by the source. The scattering halo shows a structure that includes a bright ring between 80″ and 240″ surrounding the source, and a continuous distribution beyond 250″. An analysis of the 12CO J = 1–0 map and spectrum in the line of sight to the source indicates that a molecular cloud with a radial velocity of ‑79 km s‑1 (denoted MC ‑79) is the main scattering body that creates the bright ring. We found additional clouds in the line of sight, calculated their kinematic distances, and resolved the well known “near” and “far” distance ambiguity for most of the clouds. At the favored far-distance estimate of MC ‑79, the modeling of the surface brightness profile results in a distance to 4U 1630‑47 of 11.5 ± 0.3 kpc. If MC ‑79 is at the near distance, then 4U 1630‑47 is at 4.7 ± 0.3 kpc. Future Chandra, Swift, and submillimeter radio observations not only can resolve this ambiguity, but also would provide information regarding properties of dust and the distribution of all molecular clouds along the line of sight. Using the results of this study we also discuss the nature of this source and the reasons for the observation of an anomalously low soft state during the 2010 decay.

A Puzzle in Elementary Ballistics.

ERIC Educational Resources Information Center

Haugland, Ole Anton

1983-01-01

Provides an answer to the question of why it is easy to miss when shooting uphill or downhill. Experimental results indicate that when shooting uphill or downhill, sight should not be adjusted to actual distance but to distance multiplied by the cosine of the inclination angle. (JN)

Analytical Approach to Target Detection and Localization at High-Frequency Bands Using Multipath Propagation

DTIC Science & Technology

2016-04-25

unseen directly by the antennas (both transmitter TX and receiver RX), or out of the Light- Of-Sight ( LOS ) area, as being covered by the obstacles such as...or in other words, out of the Light-Of-Sight ( LOS ) area, as being covered by the obstacles such as walls or buildings. This analysis is verified...that, we put a 1.5m high metallic wall at the distance of 1.5m from the two antennas. It is obviously that the Light Of Sight ( LOS ) is at 2.25m far

Transfer of learning on a spatial memory task between the blind and sighted people.

PubMed

Akpinar, Selcuk; Popović, Stevo; Kirazci, Sadettin

2012-12-01

The purpose of this study was to analyze the effect of two different types of feedback on a spatial memory task between the blind and blindfolded-sighted participants. Participants tried to estimate the predetermined distance by using their dominant hands. Both blind and blindfolded-sighted groups were randomly divided into two feedback subgroups as "100% frequency" and "10% bandwidth". The score of the participants was given verbally to the participants as knowledge of results (KR). The target distance was set as 60 cm. Sixty acquisition trials were performed in 4 sets each including 15 repetition afterwards immediate and delayed retention tests were undertaken. Moreover, 24 hours past the delayed retention test, the participants completed 15 no-KR trials as a transfer test (target distance was 30 cm). The results of the statistical analyses revealed no significant differences for both acquisition and retention tests. However, a significant difference was found at transfer test. 100% frequency blind group performed significantly less accurate than all other groups. As a result, it can be concluded that different types of feedback have similar effect on spatial memory task used in this study. However, types of feedback can change the performance of accuracy on transferring this skill among the blind.

Experimental evaluation of shark detection rates by aerial observers.

PubMed

Robbins, William D; Peddemors, Victor M; Kennelly, Steven J; Ives, Matthew C

2014-01-01

Aerial surveys are a recognised technique to identify the presence and abundance of marine animals. However, the capability of aerial observers to reliably sight coastal sharks has not been previously assessed, nor have differences in sighting rates between aircraft types been examined. In this study we investigated the ability of observers in fixed-wing and helicopter aircraft to sight 2.5 m artificial shark analogues placed at known depths and positions. Initial tests revealed that the shark analogues could only be detected at shallow depths, averaging only 2.5 m and 2.7 m below the water surface for observers in fixed-wing and helicopter aircraft, respectively. We then deployed analogues at shallower depths along a 5 km-long grid, and assessed their sightability to aircraft observers through a series of transects flown within 500 m. Analogues were seen infrequently from all distances, with overall sighting rates of only 12.5% and 17.1% for fixed-wing and helicopter observers, respectively. Although helicopter observers had consistently higher success rates of sighting analogues within 250 m of their flight path, neither aircraft observers sighted more than 9% of analogues deployed over 300 m from their flight paths. Modelling of sighting rates against environmental and experimental variables indicated that observations were affected by distance, aircraft type, sun glare and sea conditions, while the range of water turbidities observed had no effect. We conclude that aerial observers have limited ability to detect the presence of submerged animals such as sharks, particularly when the sharks are deeper than ∼ 2.6 m, or over 300 m distant from the aircraft's flight path, especially during sunny or windy days. The low rates of detections found in this study cast serious doubts on the use of aerial beach patrols as an effective early-warning system to prevent shark attacks.

Experimental Evaluation of Shark Detection Rates by Aerial Observers

PubMed Central

Robbins, William D.; Peddemors, Victor M.; Kennelly, Steven J.; Ives, Matthew C.

2014-01-01

Aerial surveys are a recognised technique to identify the presence and abundance of marine animals. However, the capability of aerial observers to reliably sight coastal sharks has not been previously assessed, nor have differences in sighting rates between aircraft types been examined. In this study we investigated the ability of observers in fixed-wing and helicopter aircraft to sight 2.5 m artificial shark analogues placed at known depths and positions. Initial tests revealed that the shark analogues could only be detected at shallow depths, averaging only 2.5 m and 2.7 m below the water surface for observers in fixed-wing and helicopter aircraft, respectively. We then deployed analogues at shallower depths along a 5 km-long grid, and assessed their sightability to aircraft observers through a series of transects flown within 500 m. Analogues were seen infrequently from all distances, with overall sighting rates of only 12.5% and 17.1% for fixed-wing and helicopter observers, respectively. Although helicopter observers had consistently higher success rates of sighting analogues within 250 m of their flight path, neither aircraft observers sighted more than 9% of analogues deployed over 300 m from their flight paths. Modelling of sighting rates against environmental and experimental variables indicated that observations were affected by distance, aircraft type, sun glare and sea conditions, while the range of water turbidities observed had no effect. We conclude that aerial observers have limited ability to detect the presence of submerged animals such as sharks, particularly when the sharks are deeper than ∼2.6 m, or over 300 m distant from the aircraft's flight path, especially during sunny or windy days. The low rates of detections found in this study cast serious doubts on the use of aerial beach patrols as an effective early-warning system to prevent shark attacks. PMID:24498258

MarCOs, Mars and Earth

NASA Image and Video Library

2018-03-29

An artist's rendering of the twin Mars Cube One (MarCO) spacecraft flying over Mars with Earth in the distance. The MarCOs will be the first CubeSats -- a kind of modular, mini-satellite -- flown in deep space. They're designed to fly along behind NASA's InSight lander on its cruise to Mars. If they make the journey, they will test a relay of data about InSight's entry, descent and landing back to Earth. Though InSight's mission will not depend on the success of the MarCOs, they will be a test of how CubeSats can be used in deep space. https://photojournal.jpl.nasa.gov/catalog/PIA22316

A parametric generalization of the Hayne estimator for line transect sampling

USGS Publications Warehouse

Burnham, Kenneth P.

1979-01-01

The Hayne model for line transect sampling is generalized by using an elliptical (rather than circular) flushing model for animal detection. By assuming the ration of major and minor axes lengths is constant for all animals, a model results which allows estimation of population density based directly upon sighting distances and sighting angles. The derived estimator of animal density is a generalization of the Hayne estimator for line transect sampling.

Addressing Challenges in Web Accessibility for the Blind and Visually Impaired

ERIC Educational Resources Information Center

Guercio, Angela; Stirbens, Kathleen A.; Williams, Joseph; Haiber, Charles

2011-01-01

Searching for relevant information on the web is an important aspect of distance learning. This activity is a challenge for visually impaired distance learners. While sighted people have the ability to filter information in a fast and non sequential way, blind persons rely on tools that process the information in a sequential way. Learning is…

Bridging Operational and Strategic Communication Architectures: Integrating Small Unmanned Aircraft Systems as Airborne Tactical Relay Communication Vertical Nodes

DTIC Science & Technology

2012-09-01

Surveillance Reconnaissance JUAS Joint Unmanned Aircraft System LAN Local Area Network LOS Line of Sight xiv MANET Mobile Ad Hoc Network...terrain, which severely impacted the ability to communicate with the line of sight ( LOS ) tactical radios used by small units. Much like the commercial...Selectable – NB: 10W, SATCOM: 20W, WB: 20W peak/5W average Operational Mode: Voice/Data (to 3.6Mbps) Distance: 300 meters to 35 Kilometers or LOS

Auditory cues for orientation and postural control in sighted and congenitally blind people

NASA Technical Reports Server (NTRS)

Easton, R. D.; Greene, A. J.; DiZio, P.; Lackner, J. R.

1998-01-01

This study assessed whether stationary auditory information could affect body and head sway (as does visual and haptic information) in sighted and congenitally blind people. Two speakers, one placed adjacent to each ear, significantly stabilized center-of-foot-pressure sway in a tandem Romberg stance, while neither a single speaker in front of subjects nor a head-mounted sonar device reduced center-of-pressure sway. Center-of-pressure sway was reduced to the same level in the two-speaker condition for sighted and blind subjects. Both groups also evidenced reduced head sway in the two-speaker condition, although blind subjects' head sway was significantly larger than that of sighted subjects. The advantage of the two-speaker condition was probably attributable to the nature of distance compared with directional auditory information. The results rule out a deficit model of spatial hearing in blind people and are consistent with one version of a compensation model. Analysis of maximum cross-correlations between center-of-pressure and head sway, and associated time lags suggest that blind and sighted people may use different sensorimotor strategies to achieve stability.

A Retrospective Study of Causes of Low Vision in Saud Arabia, A Case of Eye World Medical Complex in Riyadh.

PubMed

Z Alotaibi, Abdullah

2015-10-20

Vision is the ability of seeing with a definite understanding of features, color and contrast, and to distinguish between objects visually. In the year 1999, the World Health Organization (WHO) and the International Agency for the Prevention of Blindness formulated a worldwide project for the eradication of preventable loss of sight with the subject of "Vision 2020: the Right to Sight". This global program aims to eradicate preventable loss of sight by the year 2020. This study was conducted to determine the main causes of low vision in Saudi Arabia and also to assess their visual improvement after using low vision aids (LVD).The study is a retrospective study and was conducted in low vision clinic at Eye World Medical Complex in Riyadh, Saudi Arabia. The file medical record of 280 patients attending low vision clinics from February 2008 to June 2010 was included. A data sheet was filled which include: age, gender, cause of low vision, unassisted visual acuity for long distances and short distances, low vision devices needed for long distances and short distances that provides best visual acuity. The result shows that the main cause of low vision was Optic atrophy (28.9%). Retinitis pigmentosa was the second cause of low vision, accounting for 73 patients (26%) followed by Diabetic retinopathy and Macular degeneration with 44 patients (15.7%) and 16 patients (5.7%) respectively. Inter family marriage could be one of the main causes of low vision. Public awareness should be embarked on for enlightenment on ocular diseases result in consanguineous marriage. Also, it is an important issue to start establishing low vision clinics in order to improve the situation.

Construction dust amelioration techniques.

DOT National Transportation Integrated Search

2012-04-01

Dust produced on seasonal road construction sites in Alaska is both a traffic safety and environmental concern. Dust emanating from : unpaved road surfaces during construction severely reduces visibility and impacts stopping sight distance, and contr...

Construction dust amelioration techniques : [executive summary].

DOT National Transportation Integrated Search

2012-04-01

Dust produced on seasonal road construction sites in Alaska is both a traffic safety and environmental concern. Dust emanating from : unpaved road surfaces during construction severely reduces visibility and impacts stopping sight distance, and contr...

Multi-mode reliability-based design of horizontal curves.

PubMed

Essa, Mohamed; Sayed, Tarek; Hussein, Mohamed

2016-08-01

Recently, reliability analysis has been advocated as an effective approach to account for uncertainty in the geometric design process and to evaluate the risk associated with a particular design. In this approach, a risk measure (e.g. probability of noncompliance) is calculated to represent the probability that a specific design would not meet standard requirements. The majority of previous applications of reliability analysis in geometric design focused on evaluating the probability of noncompliance for only one mode of noncompliance such as insufficient sight distance. However, in many design situations, more than one mode of noncompliance may be present (e.g. insufficient sight distance and vehicle skidding at horizontal curves). In these situations, utilizing a multi-mode reliability approach that considers more than one failure (noncompliance) mode is required. The main objective of this paper is to demonstrate the application of multi-mode (system) reliability analysis to the design of horizontal curves. The process is demonstrated by a case study of Sea-to-Sky Highway located between Vancouver and Whistler, in southern British Columbia, Canada. Two noncompliance modes were considered: insufficient sight distance and vehicle skidding. The results show the importance of accounting for several noncompliance modes in the reliability model. The system reliability concept could be used in future studies to calibrate the design of various design elements in order to achieve consistent safety levels based on all possible modes of noncompliance. Copyright © 2016 Elsevier Ltd. All rights reserved.

No-passing zone system: user's manual.

DOT National Transportation Integrated Search

2016-08-01

This Users Manual is intended for traffic engineers and technicians who will be either conducting passing sight distance : measurement runs in the field or processing the collected data in the office. This Users Manual includes: : - A descripti...

40 CFR 93.126 - Exempt projects.

Code of Federal Regulations, 2014 CFR

2014-07-01

... location or feature. Safer non-Federal-aid system roads. Shoulder improvements. Increasing sight distance...). Acquisition of scenic easements. Plantings, landscaping, etc. Sign removal. Directional and informational signs. Transportation enhancement activities (except rehabilitation and operation of historic...

40 CFR 93.126 - Exempt projects.

Code of Federal Regulations, 2011 CFR

2011-07-01

... location or feature. Safer non-Federal-aid system roads. Shoulder improvements. Increasing sight distance...). Acquisition of scenic easements. Plantings, landscaping, etc. Sign removal. Directional and informational signs. Transportation enhancement activities (except rehabilitation and operation of historic...

40 CFR 93.126 - Exempt projects.

Code of Federal Regulations, 2012 CFR

2012-07-01

... location or feature. Safer non-Federal-aid system roads. Shoulder improvements. Increasing sight distance...). Acquisition of scenic easements. Plantings, landscaping, etc. Sign removal. Directional and informational signs. Transportation enhancement activities (except rehabilitation and operation of historic...

Decoupled Magnetoquasistatic Non-Line-of-Sight Position and Orientation Sensing for Arbitrary Distances

NASA Technical Reports Server (NTRS)

Arumugam, Darmindra D. (Inventor)

2017-01-01

Methods and systems for non-line-of-sight positioning are disclosed for arbitrarily short to long ranges, where positioning is achieved using a single anchor not requiring tri-/multi-lateration or tri-/multi-angulation. Magnetoquasistatic fields can be used to determine position and orientation of a device in two or three dimensions. Two or three axis coils can be used in receivers and transmitters. The magnetoquasistatic equations are solved in different scenarios, taking into consideration the image signals originating from the interaction between the fields and ground/earth.

VizieR Online Data Catalog: Kinematic data for stars in OB-associations (Melnik+, 2017)

NASA Astrophysics Data System (ADS)

Melnik, A. M.; Dambis, A. K.

2017-10-01

Table 1 gives the coordinates and kinematic parameters for OB-associations from the list by Blaha and Humphreys (1989AJ.....98.1598B). It presents the average Galactic coordinates l and b, the average heliocentric distance r, the total number of stars with known photometric measurements, Nt, used for determination of the distance for an OB-association. The distance r is equal to the distance from the catalog by Blaha and Humphreys, rBH, multiplied by a factor of 0.8, r=0.8*rBH. Table 1 also lists the median line-of-sight velocities Vr of OB-associations, the dispersions of line-of-sight velocities, sigma_vr, and the number of stars with known line-of-sight velocity nvr in an OB-association. The line-of-sight velocities of individual stars were taken from the catalog by Barbier-Brossat and Figon (1999, Cat. III/213). We used only the velocities measured with errors of less than 10 km/s which corresponds to the quality estimations A, B, C and D. We also present the median proper motions of OB-associations along l- and b-coordinates, mul and mub, derived from stellar proper motions taken from the catalog TGAS (2016, Cat. I/337), the dispersions of proper motions, sigma_mul and sigma_mub, as well as a number of stars, nmu, with known TGAS proper motions. Table 2 gives the spectral, photometric and kinematic data for stars in OB-associations. It presents the name of a star, the name of the OB-association to which it is assigned by Blaha and Humphreys (1989), spectral type of the star, code of its luminosity class cL: 2 - Ia, 4 - Iab, 6 - Ib, 8 - II, 10 - III, 12 - IV, 14 - V, where the corresponding odd numbers (1, 3,..., 13) reflect the uncertainty in its determination. Table 2 also shows the Galactic coordinates l and b of a star, the heliocentric distance r to its assigned OB-association, the line-of-sight velocity of the star Vr, if available, and its error evr taken from the catalog Barbier-Brossat and Figon (1999, Cat. III/213). Table 2 gives the Hipparcos number HIP (1997, Cat. I/239) of the star, TGAS proper motions, mul and mub, if available, and their errors (2016, Cat. I/337). If a Hipparcos star is absent in the TGAS catalog, then we give its Hipparcos proper motions and their errors (1997, Cat. I/239); flag F indicates the source of proper motions: 'G' means TGAS and 'H' - Hipparcos. Table 2 also presents color indexes B-V and U-B, apparent and absolute magnitudes, mv and Mv, and the V-band extinction, Av, adopted from the catalog by Blaha and Humphreys (1989AJ.....98.1598B). (2 data files).

Evaluation of the Prince William County collision countermeasure system.

DOT National Transportation Integrated Search

2001-02-01

The Collision Countermeasure System (CCS) is an ITS application intended to reduce side-impact accident potential at rural, limited sight-distance intersections. It consists of activated warning signs and pavement loop detectors designed to enhance d...

A Multi-Wavelength Study of the Hot Component of the Interstellar Medium

NASA Technical Reports Server (NTRS)

Nichols, Joy; Oliversen, Ronald K. (Technical Monitor)

2002-01-01

The goals of this research are as follows: (1) Using the large number of lines of sight available in the ME database, identify the lines of sight with high-velocity components in interstellar lines, from neutral species through Si VI, C IV, and N V; (2) Compare the column density of the main components (i.e. low velocity components) of the interstellar lines with distance, galactic longitude and latitude, and galactic radial position. Derive statistics on the distribution of components in space (e.g. mean free path, mean column density of a component). Compare with model predictions for the column densities in the walls of old SNR bubbles and superbubbles, in evaporating cloud boundaries and in turbulent mixing layers; (3) For the lines of sight associated with multiple high velocity, high ionization components, model the shock parameters for the associated superbubble and SNR to provide more accurate energy input information for hot phase models and galactic halo models. Thus far 49 lines of sight with at least one high velocity component to the C IV lines have been identified; and (4) Obtain higher resolution data for the lines of sight with high velocity components (and a few without) to further refine these models.

Structure of clusters with bimodal distribution of galaxy line-of-sight velocities III: A1831

NASA Astrophysics Data System (ADS)

Kopylov, A. I.; Kopylova, F. G.

2010-07-01

We study the A1831 cluster within the framework of our program of the investigation of galaxy clusters with bimodal velocity distributions (i.e., clusters where the velocities of subsystems differ by more than Δ cz ˜ 3000 km/s).We identify two subsystems in this cluster: A1831A ( cz = 18970 km/s) and A1831B ( cz = 22629 km/s) and directly estimate the distances to these subsystems using three methods applied to early-type galaxies: the Kormendy relation, the photometric plane, and the fundamental plane. To this end, we use the results of our observations made with the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences and the data adopted from the SDSS DR6 catalog. We confirmed at a 99% confidence level that (1) the two subsystems are located at different distances, which are close to their Hubble distances, and (2) the two subsystems are located behind one another along the line of sight and are not gravitationally bound to each other. Both clusters have a complex internal structure, which makes it difficult to determine their dynamical parameters. Our estimates for the velocity dispersions and masses of the two clusters: 480 km/s and 1.9 × 1014 M ⊙ for A1831A, 952 km/s and 1.4 × 1015 M ⊙ for A1831B should be views as upper limits. At least three spatially and kinematically distinct groups of galaxies can be identified in the foreground cluster A1831A, and this fact is indicative of its incomplete dynamical relaxation. Neither can we rule out the possibility of a random projection. The estimate of the mass of the main cluster A1831B based on the dispersion of the line-of-sight velocities of galaxies is two-to-three times greater than the independent mass estimates based on the total K-band luminosity, temperature, and luminosity of the X-ray gas of the cluster. This fact, combined with the peculiarities of its kinematical structure, leads us to conclude that the cluster is in a dynamically active state: galaxies and groups of galaxies with large line-of-sight velocities relative to the center of the cluster accrete onto the virialized nucleus of the cluster (possibly, along the filament directed close to the line of sight).

Methodology for safety optimization of highway cross-sections for horizontal curves with restricted sight distance.

PubMed

Ibrahim, Shewkar E; Sayed, Tarek; Ismail, Karim

2012-11-01

Several earlier studies have noted the shortcomings with existing geometric design guides which provide deterministic standards. In these standards the safety margin of the design output is generally unknown and there is little knowledge of the safety implications of deviating from the standards. To mitigate these shortcomings, probabilistic geometric design has been advocated where reliability analysis can be used to account for the uncertainty in the design parameters and to provide a mechanism for risk measurement to evaluate the safety impact of deviations from design standards. This paper applies reliability analysis for optimizing the safety of highway cross-sections. The paper presents an original methodology to select a suitable combination of cross-section elements with restricted sight distance to result in reduced collisions and consistent risk levels. The purpose of this optimization method is to provide designers with a proactive approach to the design of cross-section elements in order to (i) minimize the risk associated with restricted sight distance, (ii) balance the risk across the two carriageways of the highway, and (iii) reduce the expected collision frequency. A case study involving nine cross-sections that are parts of two major highway developments in British Columbia, Canada, was presented. The results showed that an additional reduction in collisions can be realized by incorporating the reliability component, P(nc) (denoting the probability of non-compliance), in the optimization process. The proposed approach results in reduced and consistent risk levels for both travel directions in addition to further collision reductions. Copyright © 2012 Elsevier Ltd. All rights reserved.

White-Tailed Deer Response to Vehicle Approach: Evidence of Unclear and Present Danger

PubMed Central

Blackwell, Bradley F.; Seamans, Thomas W.; DeVault, Travis L.

2014-01-01

The fundamental causes of animal-vehicle collisions are unclear, particularly at the level of animal detection of approaching vehicles and decision-making. Deer-vehicle collisions (DVCs) are especially costly in terms of animal mortality, property damage, and safety. Over one year, we exposed free-ranging white-tailed deer (Odocoileus virginianus) to vehicle approach under low ambient light conditions, from varying start distances, and vehicle speeds from 20 km/h to approximately 90 km/h. We modeled flight response by deer to an approaching vehicle and tested four hypotheses: 1) flight-initiation distance (FID) would correlate positively with start distance (indicating a spatial margin of safety); 2) deer would react to vehicle speed using a temporal margin of safety; 3) individuals reacting at greater FIDs would be more likely to cross the path of the vehicle; and 4) crossings would correlate positively with start distance, approach speed, and distance to concealing/refuge cover. We examined deer responses by quantiles. Median FID was 40% of start distance, irrespective of start distance or approach speed. Converting FID to time-to-collision (TTC), median TTC was 4.6 s, but uncorrelated with start distance or approach speed. The likelihood of deer crossing in front of the vehicle was not associated with greater FIDs or other explanatory variables. Because deer flight response to vehicle approach was highly variable, DVCs should be more likely with increasing vehicle speeds because of lower TTCs for a given distance. For road sections characterized by frequent DVCs, we recommend estimating TTC relative to vehicle speed and candidate line-of-sight distances adjusted downward by (1-P), where P represents our findings for the proportion of start distance by which >75% of deer had initiated flight. Where road design or conservation goals limit effectiveness of line-of-sight maintenance, we suggest incorporation of roadway obstacles that force drivers to slow vehicles, in addition to posting advisory speed limits. PMID:25333922

Assessing responses of humpback whales to North Pacific Acoustic Laboratory (NPAL) transmissions: results of 2001--2003 aerial surveys north of Kauai.

PubMed

Mobley, Joseph R

2005-03-01

Eight aerial surveys were flown north of the Hawaiian island of Kauai during 2001 when the North Pacific Acoustic Laboratory (NPAL) source was not transmitting, and during 2002 and 2003 when it was. All surveys were performed during the period of peak residency of humpback whales (Feb-Mar). During 2002 and 2003, surveys commenced immediately upon cessation of a 24-h cycle of transmissions. Numbers and distribution of whales observed within 40 km of the NPAL source during 2001 (source off) were compared with those observed during 2002 and 2003 (source on). A total of 75 sightings was noted during 2001, as compared with 81 and 55 during 2002 and 2003, respectively. Differences in sighting rates (sightings/km) across years were not statistically significant. Assessment of distributional changes relied upon comparisons of three measures: (a) location depths; (b) distance from the NPAL source; and (c) distance offshore. None of the distributional comparisons revealed statistically significant differences across years. Several possible interpretations are examined: (a) whales have habituated to the NPAL signal; (b) insufficient statistical power exists in the present design to detect any effects; and (c) the effects are short-lived and become undetectable shortly after the cessation of transmissions.

Lessons from a Community-Based Program to Monitor Forest Vertebrates in the Brazilian Amazon

NASA Astrophysics Data System (ADS)

Benchimol, Maíra; von Mühlen, Eduardo M.; Venticinque, Eduardo M.

2017-09-01

A large number of sustainable use reserves recently have been titled in the Brazilian Amazonia. These reserves require public participation in the design and implementation of management and monitoring programs. Species-monitoring programs that engage local stakeholders may be useful for assessing wildlife status over the long term. We collaborated on the development of a participatory program to monitor forest vertebrates in the Piagaçu-Purus Sustainable Development Reserve and to build capacity among the local people. We examined relations between the distance to the nearest human community and sighting rates of each species, and evaluated the program overall. Eighteen wildlife monitors received training in line transect and sign surveys and then conducted surveys along a total of ten transects. Sighting rates of most species in the Piagaçu-Purus Sustainable Development Reserve were higher than those reported in other Amazonian forests. Distance to the human community was not associated with the overall vertebrate sighting rate. Use of the trained monitors was successful in terms of data acquisition and engagement. The involvement of local people promoted discussions about regulation of hunting in the reserve. Implementation of community-based programs to monitor forest wildlife in Amazonian sustainable use reserves may empower local communities and assess the status of wildlife through time.

A Depth-Based Head-Mounted Visual Display to Aid Navigation in Partially Sighted Individuals

PubMed Central

Hicks, Stephen L.; Wilson, Iain; Muhammed, Louwai; Worsfold, John; Downes, Susan M.; Kennard, Christopher

2013-01-01

Independent navigation for blind individuals can be extremely difficult due to the inability to recognise and avoid obstacles. Assistive techniques such as white canes, guide dogs, and sensory substitution provide a degree of situational awareness by relying on touch or hearing but as yet there are no techniques that attempt to make use of any residual vision that the individual is likely to retain. Residual vision can restricted to the awareness of the orientation of a light source, and hence any information presented on a wearable display would have to limited and unambiguous. For improved situational awareness, i.e. for the detection of obstacles, displaying the size and position of nearby objects, rather than including finer surface details may be sufficient. To test whether a depth-based display could be used to navigate a small obstacle course, we built a real-time head-mounted display with a depth camera and software to detect the distance to nearby objects. Distance was represented as brightness on a low-resolution display positioned close to the eyes without the benefit focussing optics. A set of sighted participants were monitored as they learned to use this display to navigate the course. All were able to do so, and time and velocity rapidly improved with practise with no increase in the number of collisions. In a second experiment a cohort of severely sight-impaired individuals of varying aetiologies performed a search task using a similar low-resolution head-mounted display. The majority of participants were able to use the display to respond to objects in their central and peripheral fields at a similar rate to sighted controls. We conclude that the skill to use a depth-based display for obstacle avoidance can be rapidly acquired and the simplified nature of the display may appropriate for the development of an aid for sight-impaired individuals. PMID:23844067

Improved accuracies for satellite tracking

NASA Technical Reports Server (NTRS)

Kammeyer, P. C.; Fiala, A. D.; Seidelmann, P. K.

1991-01-01

A charge coupled device (CCD) camera on an optical telescope which follows the stars can be used to provide high accuracy comparisons between the line of sight to a satellite, over a large range of satellite altitudes, and lines of sight to nearby stars. The CCD camera can be rotated so the motion of the satellite is down columns of the CCD chip, and charge can be moved from row to row of the chip at a rate which matches the motion of the optical image of the satellite across the chip. Measurement of satellite and star images, together with accurate timing of charge motion, provides accurate comparisons of lines of sight. Given lines of sight to stars near the satellite, the satellite line of sight may be determined. Initial experiments with this technique, using an 18 cm telescope, have produced TDRS-4 observations which have an rms error of 0.5 arc second, 100 m at synchronous altitude. Use of a mosaic of CCD chips, each having its own rate of charge motion, in the focal place of a telescope would allow point images of a geosynchronous satellite and of stars to be formed simultaneously in the same telescope. The line of sight of such a satellite could be measured relative to nearby star lines of sight with an accuracy of approximately 0.03 arc second. Development of a star catalog with 0.04 arc second rms accuracy and perhaps ten stars per square degree would allow determination of satellite lines of sight with 0.05 arc second rms absolute accuracy, corresponding to 10 m at synchronous altitude. Multiple station time transfers through a communications satellite can provide accurate distances from the satellite to the ground stations. Such observations can, if calibrated for delays, determine satellite orbits to an accuracy approaching 10 m rms.

Visual demand of curves and fog-limited sight distance and its relationship to brake response time.

DOT National Transportation Integrated Search

2006-05-01

Driver distraction is a major contributing factor to automobile crashes. National Highway Traffic Safety Administration (NHTSA) has estimated that approximately 25% of crashes are attributed to driver distraction and inattention (Wang, Knipling, & Go...

Automating the process for locating no-passing zones using georeferencing data.

DOT National Transportation Integrated Search

2012-08-01

This research created a method of using global positioning system (GPS) coordinates to identify the location of no-passing zones in two-lane highways. Analytical algorithms were developed for analyzing the availability of sight distance along the ali...

Galactic Structure in the Outer Disk: The Field in the Line of Sight to the Intermediate-age Open Cluster Tombaugh 1

NASA Astrophysics Data System (ADS)

Carraro, Giovanni; Sales Silva, Joao Victor; Moni Bidin, Christian; Vazquez, Ruben A.

2017-03-01

We employ optical photometry and high-resolution spectroscopy to study a field toward the open cluster Tombaugh 1, where we identify a complex population mixture that we describe in terms of young and old Galactic thin disks. Of particular interest is the spatial distribution of the young population, which consists of dwarfs with spectral types as early as B6 and is distributed in a blue plume feature in the color-magnitude diagram. For the first time, we confirm spectroscopically that most of these stars are early-type stars and not blue stragglers or halo/thick-disk subdwarfs. Moreover, they are not evenly distributed along the line of sight but crowd at heliocentric distances between 6.6 and 8.2 kpc. We compare these results with present-day understanding of the spiral structure of the Galaxy and suggest that they trace the outer arm. This range of distances challenges current Galactic models adopting a disk cutoff at 14 kpc from the Galactic center. The young dwarfs overlap in space with an older component, which is identified as an old Galactic thin disk. Both young and old populations are confined in space since the disk is warped at the latitude and longitude of Tombaugh 1. The main effects of the warp are that the line of sight intersects the disk and entirely crosses it at the outer arm distance and that there are no traces of the closer Perseus arm, which would then be either unimportant in this sector or located much closer to the formal Galactic plane. Finally, we analyze a group of giant stars, which turn out to be located at very different distances and to possess very different chemical properties, with no obvious relation to the other populations. Based on observations carried out at Las Campanas Observatory, Chile (program ID CN009B-042), and Cerro Tololo Inter-American Observatory.

Galactic Structure in the Outer Disk: The Field in the Line of Sight to the Intermediate-Age open Cluster Tombaugh 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carraro, Giovanni; Silva, Joao Victor Sales; Bidin, Christian Moni

We employ optical photometry and high-resolution spectroscopy to study a field toward the open cluster Tombaugh 1, where we identify a complex population mixture that we describe in terms of young and old Galactic thin disks. Of particular interest is the spatial distribution of the young population, which consists of dwarfs with spectral types as early as B6 and is distributed in a blue plume feature in the color–magnitude diagram. For the first time, we confirm spectroscopically that most of these stars are early-type stars and not blue stragglers or halo/thick-disk subdwarfs. Moreover, they are not evenly distributed along the linemore » of sight but crowd at heliocentric distances between 6.6 and 8.2 kpc. We compare these results with present-day understanding of the spiral structure of the Galaxy and suggest that they trace the outer arm. This range of distances challenges current Galactic models adopting a disk cutoff at 14 kpc from the Galactic center. The young dwarfs overlap in space with an older component, which is identified as an old Galactic thin disk. Both young and old populations are confined in space since the disk is warped at the latitude and longitude of Tombaugh 1. The main effects of the warp are that the line of sight intersects the disk and entirely crosses it at the outer arm distance and that there are no traces of the closer Perseus arm, which would then be either unimportant in this sector or located much closer to the formal Galactic plane. Finally, we analyze a group of giant stars, which turn out to be located at very different distances and to possess very different chemical properties, with no obvious relation to the other populations.« less

Effects of high altitude and exercise on marksmanship.

PubMed

Tharion, W J; Hoyt, R W; Marlowe, B E; Cymerman, A

1992-02-01

The effects of exercise and high altitude (3,700 m to 4,300 m) on marksmanship accuracy and sighting time were quantified in 16 experienced marksmen. Subjects dry-fired a disabled rifle equipped with a laser-based system from a free-standing position. The 2.3-cm circular target was at a distance of 5 m. Marksmanship was assessed under the following conditions: 1) at rest at sea level; 2) immediately after a 21-km run/walk ascent from 1,800 m to 4,300 m elevation; 3) at rest during days 1 to 3 at altitude; 4) at rest during days 14 to 16 at altitude; and 5) immediately after a second ascent after 17 d at altitude. Exercise reduced marksmanship accuracy (p less than 0.05) but did not affect sighting time. Acute altitude exposure reduced marksmanship accuracy, and decreased sighting time (p less than 0.05). However, after residence at altitude, accuracy and sighting time at rest returned to sea level values. Exercise and acute altitude exposure had similar but independent detrimental effects on marksmanship.

Light propagation in Swiss-cheese models of random close-packed Szekeres structures: Effects of anisotropy and comparisons with perturbative results

NASA Astrophysics Data System (ADS)

Koksbang, S. M.

2017-03-01

Light propagation in two Swiss-cheese models based on anisotropic Szekeres structures is studied and compared with light propagation in Swiss-cheese models based on the Szekeres models' underlying Lemaitre-Tolman-Bondi models. The study shows that the anisotropy of the Szekeres models has only a small effect on quantities such as redshift-distance relations, projected shear and expansion rate along individual light rays. The average angular diameter distance to the last scattering surface is computed for each model. Contrary to earlier studies, the results obtained here are (mostly) in agreement with perturbative results. In particular, a small negative shift, δ DA≔D/A-DA ,b g DA ,b g , in the angular diameter distance is obtained upon line-of-sight averaging in three of the four models. The results are, however, not statistically significant. In the fourth model, there is a small positive shift which has an especially small statistical significance. The line-of-sight averaged inverse magnification at z =1100 is consistent with 1 to a high level of confidence for all models, indicating that the area of the surface corresponding to z =1100 is close to that of the background.

MiSight Assessment Study Spain (MASS). A 2-year randomized clinical trial.

PubMed

Ruiz-Pomeda, Alicia; Pérez-Sánchez, Belén; Valls, Isabel; Prieto-Garrido, Francisco Luis; Gutiérrez-Ortega, Ramón; Villa-Collar, César

2018-05-01

To compare myopia progression in children randomized to MiSight contact lenses (CLs) versus children corrected with single-vision spectacles (SV) over a 2-year period. Subjects aged 8 to 12 with myopia (-0.75 to -4.00 D sphere) and astigmatism (< -1.00 D cylinder) were assigned to the lens study group (MiSight) or the control group (single vision). Measurements of visual acuity and subjective refraction were taken at 6-month intervals, and axial length, anterior chamber, corneal power, and cycloplegic autorefraction were measured at the baseline, 12-month, and 24-month visits. Eighty-nine subjects were recruited. Forty-fix children were assigned to the MiSight group, and 33 to the single-vision spectacle group. In total, 74 children completed the clinical trial, with the following parameters at the beginning of the study: n =  41 in the MiSight group (age: 11.01 ± 1.23 years, spherical equivalent: -2.16 ± 0.94 D, gender: male: 21, female: 20) and n = 33 in the single-vision group (age: 10.12 ± 1.38 years, spherical equivalent: -1.75 ± 0.94 D, gender: male: 12, female: 21). After 2 years of follow-up, myopia progressed slowly in the MiSight group compared to the control group (0.45 D vs 0.74 D, p < 0.001) and there was less axial elongation in the MiSight group compared to the single-vision group (0.28 mm vs 0.44 mm, p < 0.001). Therefore, use of MiSight CLs produced lower myopia progression (39.32%) and lower axial growth of the eye (36.04%) at 2 years compared to spectacle use. MiSight contact lens wear reduces axial elongation and myopia progression in comparison to distance single-vision spectacles in children. ClinicalTrials.gov Identifier: NCT01917110.

Line-of-sight deposition method

DOEpatents

Patten, J.W.; McClanahan, E.D.; Bayne, M.A.

1980-04-16

A line-of-sight method of depositing a film having substantially 100% of theoretical density on a substrate. A pressure vessel contains a target source having a surface thereof capable of emitting particles therefrom and a substrate with the source surface and the substrate surface positioned such that the source surface is substantially parallel to the direction of the particles impinging upon the substrate surface, the distance between the most remote portion of the substrate surface receiving the particles and the source surface emitting the particles in a direction parallel to the substrate surface being relatively small. The pressure in the vessel is maintained less than about 5 microns to prevent scattering and permit line-of-sight deposition. By this method the angles of incidence of the particles impinging upon the substrate surface are in the range of from about 45/sup 0/ to 90/sup 0/ even when the target surface area is greatly expanded to increase the deposition rate.

Line-of-sight deposition method

DOEpatents

Patten, James W.; McClanahan, Edwin D.; Bayne, Michael A.

1981-01-01

A line-of-sight method of depositing a film having substantially 100% of theoretical density on a substrate. A pressure vessel contains a target source having a surface thereof capable of emitting particles therefrom and a substrate with the source surface and the substrate surface positioned such that the source surface is substantially parallel to the direction of the particles impinging upon the substrate surface, the distance between the most remote portion of the substrate surface receiving the particles and the source surface emitting the particles in a direction parallel to the substrate surface being relatively small. The pressure in the vessel is maintained less than about 5 microns to prevent scattering and permit line-of-sight deposition. By this method the angles of incidence of the particles impinging upon the substrate surface are in the range of from about 45.degree. to 90.degree. even when the target surface area is greatly expanded to increase the deposition rate.

Automated calculation of passing sight distance using GPS data

DOT National Transportation Integrated Search

2006-07-01

Most of the rural highways in the United States of America are two-lane, two-way highways. In order to ensure smooth flow of traffic, maximum-passing opportunities must be provided on these highways, where the fast moving vehicles can overtake slow m...

Statistical simulation of information transfer through non-line-of-sight atmospheric optical communication channels

NASA Astrophysics Data System (ADS)

Tarasenkov, M. V.; Belov, V. V.; Poznakharev, E. S.

2017-11-01

Impulse response of non-line-of-sight atmospheric communication channels at wavelengths of 0.3, 0.5, and 0.9 μm are compared for the case in which the optical axes of the receiver and laser radiation lie in the plane perpendicular to the Earth's surface. The most efficient communication channel depending on the base distance is determined. For a wavelength of 0.5 μm and a concrete variant of the transceiving part of the communication system, the limiting communication range and the limiting repetition frequency of pulses that can be transmitted through the communication channel are estimated.

The HI Environment of Nearby Lyman-alpha Absorbers

NASA Technical Reports Server (NTRS)

VanGorkom, J. H.; Carilli, C. L.; Stocke, John T.; Perlman, Eric S.; Shull, J. Michael

1996-01-01

We present the results of a VLA and WSRT search for H I emission from the vicinity of seven nearby clouds, which were observed in Ly-alpha absorption with HST toward Mrk 335, Mrk 501, and PKS 2155-304. Around the absorbers, we searched a volume of 4O' x 40' x 1000 km/s; for one of the absorbers we probed a velocity range of only 600 km/s. The H I mass sensitivity (5 sigma) very close to the lines of sight varies from 5 x 10(exp 6) solar mass at best to 5 x 10(exp 8) solar mass at worst. We detected H I emission in the vicinity of four out of seven absorbers. The closest galaxy we find to the absorbers is a small dwarf galaxy at a projected distance of 68 h(exp -1) kpc from the sight line toward Mrk 335. This optically uncataloged galaxy has the same velocity (V = 1970 km/s) as one of the absorbers, is fainter than the SMC, and has an H I mass of only 4 x 10(exp 7) solar mass. We found a somewhat more luminous galaxy at exactly the velocity (V = 5100 km/s) of one of the absorbers toward PKS 2155-304 at a projected distance of 230 h(exp -1) kpc from the sight line. Two other, stronger absorbers toward PKS 2155-304 at V approx. 17,000 km/s appear to be associated with a loose group of three bright spiral galaxies, at projected distances of 300 to 600 h(exp -1) kpc. These results support the conclusions emerging from optical searches that most nearby Ly-alpha forest clouds trace the large-scale structures outlined by the optically luminous galaxies, although this is still based on small-number statistics. We do not find any evidence from the H I distribution or kinematics that there is a physical association between an absorber and its closest galaxy. While the absorbing clouds are at the systemic velocity of the galaxies, the H I extent of the galaxies is fairly typical, and at least an order of magnitude smaller than the projected distance to the sight line at which the absorbers are seen. On the other hand, we also do not find evidence against such a connection. In total, we detected H I emission from five galaxies, of which two were previously uncataloged and one did not have a known redshift. No H I emission was detected from the vicinity of the two absorbers, which are located in a void and a region of very low galaxy density; but the limits are somewhat less stringent than for the other sight lines. These results are similar to what has been found in optically unbiased H I surveys. Thus, presence of Ly-alpha absorbers does not significantly alter the H I detection rate in their environment.

Automated calculation of passing sight distance using global positioning system data

DOT National Transportation Integrated Search

2006-07-01

Most of the rural highways in the United States of America are two-lane, two-way highways. In order to ensure smooth flow of traffic, maximum-passing opportunities must be provided on these highways, where the fast moving vehicles can overtake slow m...

A Path Loss Model for Non-Line-of-Sight Ultraviolet Multiple Scattering Channels

DTIC Science & Technology

2010-01-01

scattering is self -governed, and the distances and angles for different scattering events are conditioned on previous quantities. Therefore, the arrival...solid angle of the receiver determined by the receiver area and distance rn. Note that no integration over rn is needed because it is a function of...www.eurasip.org). This year edition will take place in Barcelona, capital city of Catalonia (Spain), and will be jointly organized by the Centre Tecnològic de

Changes in the Distribution of Red Foxes (Vulpes vulpes) in Urban Areas in Great Britain: Findings and Limitations of a Media-Driven Nationwide Survey

PubMed Central

Scott, Dawn M.; Berg, Maureen J.; Tolhurst, Bryony A.; Chauvenet, Alienor L. M.; Smith, Graham C.; Neaves, Kelly; Lochhead, Jamie; Baker, Philip J.

2014-01-01

Urbanization is one of the major forms of habitat alteration occurring at the present time. Although this is typically deleterious to biodiversity, some species flourish within these human-modified landscapes, potentially leading to negative and/or positive interactions between people and wildlife. Hence, up-to-date assessment of urban wildlife populations is important for developing appropriate management strategies. Surveying urban wildlife is limited by land partition and private ownership, rendering many common survey techniques difficult. Garnering public involvement is one solution, but this method is constrained by the inherent biases of non-standardised survey effort associated with voluntary participation. We used a television-led media approach to solicit national participation in an online sightings survey to investigate changes in the distribution of urban foxes in Great Britain and to explore relationships between urban features and fox occurrence and sightings density. Our results show that media-based approaches can generate a large national database on the current distribution of a recognisable species. Fox distribution in England and Wales has changed markedly within the last 25 years, with sightings submitted from 91% of urban areas previously predicted to support few or no foxes. Data were highly skewed with 90% of urban areas having <30 fox sightings per 1000 people km−2. The extent of total urban area was the only variable with a significant impact on both fox occurrence and sightings density in urban areas; longitude and percentage of public green urban space were respectively, significantly positively and negatively associated with sightings density only. Latitude, and distance to nearest neighbouring conurbation had no impact on either occurrence or sightings density. Given the limitations associated with this method, further investigations are needed to determine the association between sightings density and actual fox density, and variability of fox density within and between urban areas in Britain. PMID:24919063

Blind and sighted pedestrians' road-crossing judgments at a single-lane roundabout.

PubMed

Guth, David A; Long, Richard G; Emerson, Robert S Wall; Ponchillia, Paul E; Ashmead, Daniel H

2013-06-01

The aim of this study was to evaluate the relative risk and efficiency of road crossing experienced by blind and sighted pedestrians at a single-lane roundabout with two levels of traffic volume and at two distances from the roundabout. With the rapid spread of modern roundabouts across the United States,their accessibility to blind pedestrians has become an important concern. To date, accessibility research relevant to blind pedestrians has focused on multilane roundabouts, and single-lane roundabouts have been virtually ignored. Blind and sighted participants made judgments about when they would cross a single-lane roundabout with high and low traffic volumes, at exit and entry lanes, and at the actual crosswalks and at locations farther from the roundabout. Relative to sighted participants, blind participants' judgments about when to cross were more frequently risky, especially when traffic volume was high. Blind participants also were slower to make crossing judgments and accepted fewer crossing opportunities. Both groups made somewhat safer and more efficient judgments at locations farther from the roundabout. Some single-lane roundabouts may pose greater risk to blind pedestrians than to sighted pedestrians, especially when traffic volume is high. Crosswalk location merits further investigation as a design issue. These findings are relevant to transportation planners and engineers who are responsible for the accessibility of public rights-of-way.

Building Astronomy Curriculum to Include the Sight Impaired: Week long summer camp activities for Middle School Students adherent to Washington State Curriculum Standards (EALR's)

NASA Astrophysics Data System (ADS)

Ramien, Natalie; Loebman, S. R.; Player, V.; Larson, A.; Torcolini, N. B.; Traverse, A.

2011-01-01

Currently astronomy learning is heavily geared towards visual aids; however, roughly 10 million people in North America are sight impaired. Every student should have access to meaningful astronomy curriculum; an understanding of astronomy is an expectation of national and state science learning requirements. Over the last ten years, Noreen Grice has developed Braille and large print astronomy text books aimed at sight impaired learners. We build upon Grice's written work and present here a five day lesson plan that integrates 2D reading with 3D activities. Through this curriculum, students develop an intuitive understanding of astronomical distance, size, composition and lifetimes. We present five distinct lesson modules that can be taught individually or in a sequential form: the planets, our sun, stars, stellar evolution and galaxies. We have tested these modules on sight impaired students and report the results here. Overall, we find the work presented here lends itself equally well to a week long science camp geared toward middle school sight impaired taught by astronomers or as supplemental material integrated into a regular classroom science curriculum. This work was made possible by a 2007 Simple Effective Education and Dissemination (SEED) Grant For Astronomy Researchers, Astronomical Society of the Pacific through funds provided by the Planck Mission, Jet Propulsion Laboratory, California Institute of Technology.

Innovative Roadway Design for Recreation Areas.

DTIC Science & Technology

1982-02-01

Volume Roadways by Terrain Condition (Kearney, 1979) DHV* Maximum Grade (M) ( vph ) Level Rolling Mountainous 100 7 10 12 100-400 7 9 10 400 6 7 9 * DHV...design hourly volume; vph = vehicles per hour. j. Design of the vertical alignment is also affected by using the reduced sight distances discussed

Near-Surface Flow Fields Deduced Using Correlation Tracking and Time-Distance Analysis

NASA Technical Reports Server (NTRS)

DeRosa, Marc; Duvall, T. L., Jr.; Toomre, Juri

1999-01-01

Near-photospheric flow fields on the Sun are deduced using two independent methods applied to the same time series of velocity images observed by SOI-MDI on SOHO. Differences in travel times between f modes entering and leaving each pixel measured using time-distance helioseismology are used to determine sites of supergranular outflows. Alternatively, correlation tracking analysis of mesogranular scales of motion applied to the same time series is used to deduce the near-surface flow field. These two approaches provide the means to assess the patterns and evolution of horizontal flows on supergranular scales even near disk center, which is not feasible with direct line-of-sight Doppler measurements. We find that the locations of the supergranular outflows seen in flow fields generated from correlation tracking coincide well with the locations of the outflows determined from the time-distance analysis, with a mean correlation coefficient after smoothing of bar-r(sub s) = 0.840. Near-surface velocity field measurements can used to study the evolution of the supergranular network, as merging and splitting events are observed to occur in these images. The data consist of one 2048-minute time series of high-resolution (0.6" pixels) line-of-sight velocity images taken by MDI on 1997 January 16-18 at a cadence of one minute.

In-vehicle signing functions of an in-vehicle information system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tufano, D.R.; Knee, H.E.; Spelt, P.F.

The definition of In-Vehicle Signing (IVS) functions was guided by the principles of traffic engineering as they apply to the design and placement of roadway signs. Because of the dynamic and active nature of computing, communications, and display technology, IVS can fulfill the signing principles of traffic engineering in ways that have been impossible with conventional signage. Current signing technology represents a series of compromises of these principles, especially the data and equations contributing to the calculation of required sight distance. A number of conditions relevant to sight distance are quite variable, e.g.: vehicle speed, visibility, weather, and driver reactionmore » time. However, conventional signing requires that there are fixed values of each variable for the determination of (e.g.) legibility distance. IVS, on the other hand, will be able to tailor the timing of sign presentation to the dynamically diverse variable values of all of these conditions. A clear, in-vehicle sign display, adaptive to ambient and driver conditions, will in fact obviate the entire issue of sign legibility. These capabilities, together with information filtering functions, will truly enhance the presentation of sign information to drivers. The development of IVS is a critical step in the development of an integrated In-Vehicle Information System (IVIS).« less

The perception of distances and spatial relationships in natural outdoor environments.

PubMed

Norman, J Farley; Crabtree, Charles E; Clayton, Anna Marie; Norman, Hideko F

2005-01-01

The ability of observers to perceive distances and spatial relationships in outdoor environments was investigated in two experiments. In experiment 1, the observers adjusted triangular configurations to appear equilateral, while in experiment 2, they adjusted the depth of triangles to match their base width. The results of both experiments revealed that there are large individual differences in how observers perceive distances in outdoor settings. The observers' judgments were greatly affected by the particular task they were asked to perform. The observers who had shown no evidence of perceptual distortions in experiment 1 (with binocular vision) demonstrated large perceptual distortions in experiment 2 when the task was changed to match distances in depth to frontal distances perpendicular to the observers' line of sight. Considered as a whole, the results indicate that there is no single relationship between physical and perceived space that is consistent with observers' judgments of distances in ordinary outdoor contexts.

The modified "Rockfall Hazard Rating System": a new tool for roads risk assessment

NASA Astrophysics Data System (ADS)

Budetta, P.

2003-04-01

This paper contains a modified method for the analysis of rockfall hazard along roads and motorways. The method is derived from that one developed by Pierson et alii at the Oregon State Highway Division. The Rockfall Hazard Rating System (RHRS) provides a rational way to make informed decisions on where and how to spend construction funds. An exponential scoring graph is used to represent the increase in hazard that is reflected in the nine categories forming the classification (slope height, ditch effectiveness, average vehicle risk, percent of decision site distance, roadway width, geological character, quantity of rockfall/event, climate and rock fall history). The resulting total score contains the essential elements regarding the evaluation of the consequences ("cost of failure"). In the modified method, the rating for the categories "ditch effectiveness", "decision sight distance", "rodway width", "geologic characteristic" and "climate and water circulation" have been rendered more easy and objective. The main modifications regard the introduction of the Romana's Slope Mass Rating improving the estimate of the geologic characteristics, of the volume of the potentially unstable blocks and underground water circulation. Other modifications regard the scoring determination for the categories "decision sight distance" and "road geometry". For these categories, the Italian National Council's standards (CNR) have been used. The method must be applied in both the traffic directions because the percentage of reduction in the "decision sight distance" greatly affects the results. An application of the method to a 2-km-long section of the Sorrentine road (n° 145) in Southern Italy was pointed out. A high traffic intensity affects the entire section of the road and rockfalls periodically cause casualties, as well as a large amount of damage and traffic interruptions. The method was applied on seven cross section traces of slopes adjacent to the Sorrentine road and the total final scores range between 275 and 450. For these slopes, the analysis shows that the risk is unacceptable and it must reduced using urgent remedial works. Further applications in other geological environments are welcomed.

A Multi-Wavelength Study of the Hot Component of the Interstellar Medium

NASA Technical Reports Server (NTRS)

Oliversen, Ronald J. (Technical Monitor)

2004-01-01

This research focuses on the kinematics and evolution of the hot phase of the interstellar medium in the Galaxy. The plan was to measure the UV spectra of all hot stars observed with IUE, in order to identify and measure the main component and any high velocity components to the interstellar lines. Collection of data from higher resolution instruments on HST has been proposed for some of the interesting lines of sight. IUE spectra of 240 stars up to 8 kpc in 2 quadrants of the galactic plane have been examined to (1) estimate the total column density per kpc as a function of direction and distance, and (2) to obtain a lower limit to the number of high velocity components to the interstellar lines, thus giving an approximation of the number of conductive interfaces encountered per line of sight. By determining an approximation to the number of components per unit distance we aim to derive statistics on interfaces between hot and cold gas in the Galaxy. We find that 20% of the stars in this sample show at least one high velocity component in the C IV interstellar line. Two successful FUSE programs address this research and collected data for several of the lines of sight identified as locations of hot, expanding gas with the IUE data. One FUSE program is complete for the Vela SNR region. Data from another FUSE program to investigate the Cygnus superbubble region are being analyzed.

A Homing Missile Control System to Reduce the Effects of Radome Diffraction

NASA Technical Reports Server (NTRS)

Smith, Gerald L.

1960-01-01

The problem of radome diffraction in radar-controlled homing missiles at high speeds and high altitudes is considered from the point of view of developing a control system configuration which will alleviate the deleterious effects of the diffraction. It is shown that radome diffraction is in essence a kinematic feedback of body angular velocities which causes the radar to sense large apparent line-of-sight angular velocities. The normal control system cannot distinguish between the erroneous and actual line-of-sight rates, and entirely wrong maneuvers are produced which result in large miss distances. The problem is resolved by adding to the control system a special-purpose computer which utilizes measured body angular velocity to extract from the radar output true line-of-sight information for use in steering the missile. The computer operates on the principle of sampling and storing the radar output at instants when the body angular velocity is low and using this stored information for maneuvering commands. In addition, when the angular velocity is not low the computer determines a radome diffraction compensation which is subtracted from the radar output to reduce the error in the sampled information. Analog simulation results for the proposed control system operating in a coplanar (vertical plane) attack indicate a potential decrease in miss distance to an order of magnitude below that for a conventional system. Effects of glint noise, random target maneuvers, initial heading errors, and missile maneuverability are considered in the investigation.

VizieR Online Data Catalog: HSTPROMO. III. Dynamical distances (Watkins+, 2015)

NASA Astrophysics Data System (ADS)

Watkins, L. L.; van der Marel, R. P.; Bellini, A.; Anderson, J.

2016-02-01

For our analysis, we use the HST proper-motion (PM) catalogs described in Bellini et al. (Paper I, 2014, J/ApJ/797/115); based on archival HST images spanning 2002 to 2013. We augment these catalogs with line of sight (LOS) velocity data available in the literature. (2 data files).

Identification of PSR1758-23 as a runaway pulsar from the supernova remnant W28

NASA Technical Reports Server (NTRS)

Frall, D. A.; Kulkarni, S. R.; Vasisht, G.

1993-01-01

New observations are presented which indicate that the large dispersion and scattering of the pulses from PSR1758-23 are caused by a dense screen of ionized material located along the line of sight. This reconciles the distances to the pulsar with that to SNR W28.

Can we detect Galactic spiral arms? 3D dust distribution in the Milky Way

NASA Astrophysics Data System (ADS)

Rezaei Kh., Sara; Bailer-Jones, Coryn A. L.; Fouesneau, Morgan; Hanson, Richard

2018-04-01

We present a model to map the 3D distribution of dust in the Milky Way. Although dust is just a tiny fraction of what comprises the Galaxy, it plays an important role in various processes. In recent years various maps of dust extinction have been produced, but we still lack a good knowledge of the dust distribution. Our presented approach leverages line-of-sight extinctions towards stars in the Galaxy at measured distances. Since extinction is proportional to the integral of the dust density towards a given star, it is possible to reconstruct the 3D distribution of dust by combining many lines-of-sight in a model accounting for the spatial correlation of the dust. Such a technique can be used to infer the most probable 3D distribution of dust in the Galaxy even in regions which have not been observed. This contribution provides one of the first maps which does not show the ``fingers of God'' effect. Furthermore, we show that expected high precision measurements of distances and extinctions offer the possibility of mapping the spiral arms in the Galaxy.

Optical drift effects in general relativity

NASA Astrophysics Data System (ADS)

Korzyński, Mikołaj; Kopiński, Jarosław

2018-03-01

We consider the question of determining the optical drift effects in general relativity, i.e. the rate of change of the apparent position, redshift, Jacobi matrix, angular distance and luminosity distance of a distant object as registered by an observer in an arbitrary spacetime. We present a fully relativistic and covariant approach, in which the problem is reduced to a hierarchy of ODE's solved along the line of sight. The 4-velocities and 4-accelerations of the observer and the emitter and the geometry of the spacetime along the line of sight constitute the input data. We build on the standard relativistic geometric optics formalism and extend it to include the time derivatives of the observables. In the process we obtain two general, non-perturbative relations: the first one between the gravitational lensing, represented by the Jacobi matrix, and the apparent position drift, also called the cosmic parallax, and the second one between the apparent position drift and the redshift drift. The applications of the results include the theoretical study of the drift effects of cosmological origin (so-called real-time cosmology) in numerical or exact Universe models.

Supernovae as probes of cosmic parameters: estimating the bias from under-dense lines of sight

DOE Office of Scientific and Technical Information (OSTI.GOV)

Busti, V.C.; Clarkson, C.; Holanda, R.F.L., E-mail: vinicius.busti@uct.ac.za, E-mail: holanda@uepb.edu.br, E-mail: chris.clarkson@uct.ac.za

2013-11-01

Correctly interpreting observations of sources such as type Ia supernovae (SNe Ia) require knowledge of the power spectrum of matter on AU scales — which is very hard to model accurately. Because under-dense regions account for much of the volume of the universe, light from a typical source probes a mean density significantly below the cosmic mean. The relative sparsity of sources implies that there could be a significant bias when inferring distances of SNe Ia, and consequently a bias in cosmological parameter estimation. While the weak lensing approximation should in principle give the correct prediction for this, linear perturbationmore » theory predicts an effectively infinite variance in the convergence for ultra-narrow beams. We attempt to quantify the effect typically under-dense lines of sight might have in parameter estimation by considering three alternative methods for estimating distances, in addition to the usual weak lensing approximation. We find in each case this not only increases the errors in the inferred density parameters, but also introduces a bias in the posterior value.« less

Line-of-sight measurements for the NIF Neutron Imaging System and determination of line-of-sight offsets in OPAS 90-135 images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frank, Matthias; Fittinghoff, David N.; Bower, Dan E.

2011-05-13

This report describes line-of-sight (LOS) measurements for the NIF Neutron Imaging System (NIS) and a characterization of the NIS LOS relative to OPAS 90-135 that were performed during the NIS commissioning Nov. 2010 – Jan. 2011. As described here, data from those measurements were used to determine the relative offsets between the TCC position (x and y pixel coordinates in OPAS images) and the NIS LOS as functions of the OPAS focal distance. This data is needed to place the NIS pinhole array (PHA) onto the NIS LOS with high precision using OPAS imaging of alignment fiducials attached to themore » front and the back of the PHA. (A description of the PHA alignment fiducials, data from metrology performed on the fiducials and a description on how these fiducials were used to align the PHA for the first NIS imaging shot on Feb,. 17, 2011 will be summarized in an upcoming separate report. This report consists of an overview given in this document and a main body that consists of a set of viewgraphs (see Appendix 1) that were iterated and refined within the NIS team and with the Alignment Working Group and that contain more detailed information, schematics and calculations of the NIS line of sight offset from the OPAS LOS. See also Drury, “OPAS 90-135 Registration of Neutron Imaging System Line of Sight,” January 2011, NIF-5035484.« less

Measuring the Dust Grains and Distance to X Persei Via Its X-ray Halo

NASA Astrophysics Data System (ADS)

Smith, Randall

2006-09-01

We propose to observe the X-ray halo of the high mass X-ray binary pulsar X Per to measure interstellar dust grains along the line of sight (LOS) and to determine the distance to X Per. The X-ray halo is formed by scattering from grains along the LOS, which for X Per appear to be concentrated in one molecular cloud. Unlike many other X-ray halo observations, this low-absorption high-latitude sightline is well-characterized from absorption spectroscopy done with HST, Copernicus, and FUSE. This halo observation will measure the distance to the cloud and the dust size distribution in it. We will also be able to determine the distance to X Per by measuring the time delayed pulses in the X-ray halo.

H0LiCOW - III. Quantifying the effect of mass along the line of sight to the gravitational lens HE 0435-1223 through weighted galaxy counts★

NASA Astrophysics Data System (ADS)

Rusu, Cristian E.; Fassnacht, Christopher D.; Sluse, Dominique; Hilbert, Stefan; Wong, Kenneth C.; Huang, Kuang-Han; Suyu, Sherry H.; Collett, Thomas E.; Marshall, Philip J.; Treu, Tommaso; Koopmans, Leon V. E.

2017-06-01

Based on spectroscopy and multiband wide-field observations of the gravitationally lensed quasar HE 0435-1223, we determine the probability distribution function of the external convergence κext for this system. We measure the under/overdensity of the line of sight towards the lens system and compare it to the average line of sight throughout the Universe, determined by using the CFHTLenS (The Canada France Hawaii Lensing Survey) as a control field. Aiming to constrain κext as tightly as possible, we determine under/overdensities using various combinations of relevant informative weighting schemes for the galaxy counts, such as projected distance to the lens, redshift and stellar mass. We then convert the measured under/overdensities into a κext distribution, using ray-tracing through the Millennium Simulation. We explore several limiting magnitudes and apertures, and account for systematic and statistical uncertainties relevant to the quality of the observational data, which we further test through simulations. Our most robust estimate of κext has a median value κ^med_ext = 0.004 and a standard deviation σκ = 0.025. The measured σκ corresponds to 2.5 per cent relative uncertainty on the time delay distance, and hence the Hubble constant H0 inferred from this system. The median κ^med_ext value varies by ˜0.005 with the adopted aperture radius, limiting magnitude and weighting scheme, as long as the latter incorporates galaxy number counts, the projected distance to the main lens and a prior on the external shear obtained from mass modelling. This corresponds to just ˜0.5 per cent systematic impact on H0. The availability of a well-constrained κext makes HE 0435-1223 a valuable system for measuring cosmological parameters using strong gravitational lens time delays.

Local Interstellar Medium Properties and Deuterium Abundances for the Lines of Sight Toward HR 1099, 31 Comae, beta Ceti, and beta Cassiopeiae

NASA Technical Reports Server (NTRS)

Piskunov, Nikolai; Wood, Brian E.; Linsky, Jeffrey L.; Dempsey, Robert C.; Ayres, Thomas R.

1997-01-01

We analyze Goddard High-Resolution Spectrograph data to infer the properties of local interstellar gas and the Deuterium/Hydrogen (D/H) ratio for lines of sight toward four nearby late-type stars-HR 1099, 31 Comae, beta Ceti, and beta Cassiopeiae. The data consist of spectra of the hydrogen and deuterium Lyman-(alpha) lines, and echelle spectra of the Mg IIh and k lines toward all stars except beta Cas. Spectra of the RS CVn-type spectroscopic binary system HR 1099 were obtained near opposite quadratures to determine the intrinsic stellar emission line profile and the interstellar absorption separately. Multiple-velocity components were found toward HR 1099 and beta Cet. The spectra of 31 Com and beta Cet are particularly interesting because they sample lines of sight toward the north and south Galactic poles, respectively, for which H I and D I column densities were not previously available. The north Galactic pole appears to be a region of low hydrogen density like the 'interstellar tunnel' toward epsilon CMa. The temperature and turbulent velocities of the Local InterStellar Medium (LISM) that we measure for the lines of sight toward HR 1099, 31 Com, beta Cet, and beta Cas are similar to previously measured values (T approx.7000 K and xi = 1.0-1.6 km/s). The deuterium/hydrogen ratios found for these lines of sight are also consistent with previous measurements of other short lines of sight, which suggest D/H approx. 1.6 x 10(sup -5). In contrast, the Mg abundance measured for the beta Cet line of sight (implying a logarithmic depletion of D(Mg) = +0.30 +/- 0.15) is about 5 times larger than the Mg abundance previously observed toward alpha Cen, and about 20 times larger than all other previous measurements for the LISM. These results demonstrate that metal abundances in the LISM vary greatly over distances of only a few parsecs.

Bore-sight calibration of the profile laser scanner using a large size exterior calibration field

NASA Astrophysics Data System (ADS)

Koska, Bronislav; Křemen, Tomáš; Štroner, Martin

2014-10-01

The bore-sight calibration procedure and results of a profile laser scanner using a large size exterior calibration field is presented in the paper. The task is a part of Autonomous Mapping Airship (AMA) project which aims to create s surveying system with specific properties suitable for effective surveying of medium-wide areas (units to tens of square kilometers per a day). As is obvious from the project name an airship is used as a carrier. This vehicle has some specific properties. The most important properties are high carrying capacity (15 kg), long flight time (3 hours), high operating safety and special flight characteristics such as stability of flight, in terms of vibrations, and possibility to flight at low speed. The high carrying capacity enables using of high quality sensors like professional infrared (IR) camera FLIR SC645, high-end visible spectrum (VIS) digital camera and optics in the visible spectrum and tactical grade INSGPS sensor iMAR iTracerRT-F200 and profile laser scanner SICK LD-LRS1000. The calibration method is based on direct laboratory measuring of coordinate offset (lever-arm) and in-flight determination of rotation offsets (bore-sights). The bore-sight determination is based on the minimization of squares of individual point distances from measured planar surfaces.

Gender-related effects of vision impairment characteristics on depression in Korea.

PubMed

Park, Hye Won; Lee, Wanhyung; Yoon, Jin-Ha

2018-04-01

To investigate the gender-specific associations between perceived vision impairment and symptoms of depression. We used the data from the 2012 Korean Longitudinal Study of Aging database of 7448 individuals aged 45 years and older. Questionnaires assessing depression symptoms and perceived visual impairment at near, distance, and in general were administered. Logistic regression analyses were used to evaluate if visual impairment could lead to depression, adjusting for the potential confounders of age, socioeconomic status (household income, education level, marital status, and employment status), and health behaviors (alcohol consumption, smoking, and physical activity level) after gender stratification. Perceived general and near vision impairment were significantly associated with symptoms of depression in males (odds ratio [OR] = 2.78 and 2.54; 95% confidence interval [CI], 1.91-4.04 and 1.78-3.63). Perceived general and distance vision impairment were significantly associated with symptoms of depression in females (OR = 2.16 and 2.08; 95% CI, 1.67-2.79 and 1.61-2.69). General sight with near vision impairment in males and general sight with distance vision impairment in females could be stronger predictors of depression than other vision impairment combinations (area under the receiver operating characteristic curve [AUROC], 0.6461; p = 0.0425 in males; AUROC, 0.6270; p = 0.0318 in females). Conclusion Gender differences were found in the characteristics of visual impairment on symptoms of depression. Ophthalmologists should be aware that near vision impairment in males and distance vision impairment in females have an adjunctive effect that might contribute to symptoms of depression.

Expansion patterns and parallaxes for planetary nebulae

NASA Astrophysics Data System (ADS)

Schönberner, D.; Balick, B.; Jacob, R.

2018-02-01

Aims: We aim to determine individual distances to a small number of rather round, quite regularly shaped planetary nebulae by combining their angular expansion in the plane of the sky with a spectroscopically measured expansion along the line of sight. Methods: We combined up to three epochs of Hubble Space Telescope imaging data and determined the angular proper motions of rim and shell edges and of other features. These results are combined with measured expansion speeds to determine individual distances by assuming that line of sight and sky-plane expansions are equal. We employed 1D radiation-hydrodynamics simulations of nebular evolution to correct for the difference between the spectroscopically measured expansion velocities of rim and shell and of their respective shock fronts. Results: Rim and shell are two independently expanding entities, driven by different physical mechanisms, although their model-based expansion timescales are quite similar. We derive good individual distances for 15 objects, and the main results are as follows: (i) distances derived from rim and shell agree well; (ii) comparison with the statistical distances in the literature gives reasonable agreement; (iii) our distances disagree with those derived by spectroscopic methods; (iv) central-star "plateau" luminosities range from about 2000 L⊙ to well below 10 000 L⊙, with a mean value at about 5000 L⊙, in excellent agreement with other samples of known distance (Galactic bulge, Magellanic Clouds, and K648 in the globular cluster M 15); (v) the central-star mass range is rather restricted: from about 0.53 to about 0.56 M⊙, with a mean value of 0.55 M⊙. Conclusions: The expansion measurements of nebular rim and shell edges confirm the predictions of radiation-hydrodynamics simulations and offer a reliable method for the evaluation of distances to suited objects. Results of this paper are based on observations made with the NASA/ESA Hubble Space Telescope in Cycle 16 (GO11122) and older data obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Coupling of Head and Body Movement with Motion of the Audible Environment

ERIC Educational Resources Information Center

Stoffregen, Thomas A.; Villard, Sebastien; Kim, ChungGon; Ito, Kiyohide; Bardy, Benoit G.

2009-01-01

The authors asked whether standing posture could be controlled relative to audible oscillation of the environment. Blindfolded sighted adults were exposed to acoustic flow in a moving room, and were asked to move so as to maintain a constant distance between their head and the room. Acoustic flow had direct (source) and indirect (reflected)…

76 FR 68720 - Takes of Marine Mammals Incidental to Specified Activities; Low-Energy Marine Geophysical Survey...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-07

... (if consistent), bearing and distance from the seismic vessel, sighting cue, apparent reaction of the... mitigation measure and marine mammal reaction to ramp-up would be useful information in this regard. NMFS has... reactions (or lack thereof) by all types of marine mammals to seismic research activities. The U.S. Navy's...

Kite Aerial Photography as a Tool for Remote Sensing

ERIC Educational Resources Information Center

Sallee, Jeff; Meier, Lesley R.

2010-01-01

As humans, we perform remote sensing nearly all the time. This is because we acquire most of our information about our surroundings through the senses of sight and hearing. Whether viewed by the unenhanced eye or a military satellite, remote sensing is observing objects from a distance. With our current technology, remote sensing has become a part…

The Importance of Orientation and Mobility Skills for Students Who Are Deaf-Blind. Revised

ERIC Educational Resources Information Center

Gense, D. Jay; Gense, Marilyn

2004-01-01

Children learn about their environment as they move through it--about people and objects, sizes, shapes, and distances. For typically developing children the senses of sight and hearing provide the greatest motivation for exploration. These children will use their vision and hearing to gather information about their surroundings while growing in…

The Carnegie Hubble Program: The Infrared Leavitt Law in IC 1613

NASA Technical Reports Server (NTRS)

Scowcroft, Victoria; Freedman, Wendy L.; Madore, Barry F.; Monson, Andrew J.; Persson, S. E.; Seibert, Mark; Rigby, Jane R.; Melbourne, Jason

2013-01-01

We have observed the dwarf galaxy IC 1613 at multiple epochs in the midinfrared using Spitzer and the in the near-infrared using the new FourStar near-IR camera on Magellan. We have constructed Cepheid period luminosity relations in the J, H, Ks, [3.6] and [4.5] bands and have used the run of their apparent distance moduli as a function of wavelength to derive the line of sight reddening and distance to IC 1613. Using a nineband fit, we find E(BV ) = 0.050.01 mag and an extinction corrected distance modulus of 0 = 24.29 0.03statistical 0.03systematic mag. By comparing our multiband and [3.6] distance moduli to results from the tip of the red giant branch and red clump distance indicators, we find that metallicity has no measurable effect on Cepheid distances at 3.6 m in the metallicity range 1.0 [Fe/H] 0.2, hence derivations of the Hubble constant at this wavelength require no correction for metallicity.

VizieR Online Data Catalog: Extinction map towards the Galactic bulge (Chen+, 2013)

NASA Astrophysics Data System (ADS)

Chen, B.; Schultheis, M.; Jiang, B.; Gonzalez, O. A.; Robin, A. C.; Rejkuba, M.; Minniti, D.

2012-11-01

We combine the observations with the Besancon model of the Galaxy to investigate the variations of extinction along different lines of sight towards the inner Galactic bulge as a function of distance. The full results are listed in Table 1 and Table 2. These results will be also added into the BEAM calculator webpage (http://mill.astro.puc.cl/BEAM/calculator.php). For each position we give the E(J-Ks), E(H-Ks) as well as the corresponding sigma for each distance bin starting from 1 to 10kpc. (2 data files).

Assessment of Indoor Route-finding Technology for People with Visual Impairment

PubMed Central

Kalia, Amy A.; Legge, Gordon E.; Roy, Rudrava; Ogale, Advait

2010-01-01

This study investigated navigation with route instructions generated by digital-map software and synthetic speech. Participants, either visually impaired or sighted wearing blind folds, successfully located rooms in an unfamiliar building. Users with visual impairment demonstrated better route-finding performance when the technology provided distance information in number of steps rather than walking time or number of feet. PMID:21869851

Spatiotemporal characteristics of motor actions by blind long jump athletes.

PubMed

Torralba, Miguel Angel; Padullés, José María; Losada, Jose Luis; López, Jose Luis

2017-01-01

Blind people depend on spatial and temporal representations to perform activities of daily living and compete in sport. The aim of this study is to determine the spatiotemporal characteristics of long jumps performed by blind athletes and compare findings with those reported for sighted athletes. We analysed a sample of 12 male athletes competing in the F11 Long Jump Finals at the Paralympic Games in London 2012. Performances were recorded using four high-speed cameras, and speeds were measured using a radar speed gun. The images were processed using validated image analysis software. The long jump run-up is shorter in blind athletes than in sighted athletes. We observed statistically significant differences for body centre of mass velocity and an increase in speed over the last three strides prior to take-off, contrasting with reports for sighted athletes and athletes with less severe visual impairment, who maintain or reduce their speed during the last stride. Stride length for the last three strides was the only spatial characteristic that was not significantly associated with effective jump distance. Blind long jumpers extend rather than shorten their last stride. Contact time with the take-off board is longer than that reported for sighted athletes. The actions of blind long jumpers, unlike those without disabilities, do not vary their leg actions during the final runway approach for optimal placement on the take-off board.

Validation of stereophotogrammetry of the human torso.

PubMed

Lee, Juhun; Kawale, Manas; Merchant, Fatima A; Weston, June; Fingeret, Michelle C; Ladewig, Dianne; Reece, Gregory P; Crosby, Melissa A; Beahm, Elisabeth K; Markey, Mia K

2011-02-15

The objective of this study was to determine if measurements of breast morphology computed from three-dimensional (3D) stereophotogrammetry are equivalent to traditional anthropometric measurements obtained directly on a subject using a tape measure. 3D torso images of 23 women ranged in age from 36 to 63 who underwent or were scheduled for breast reconstruction surgery were obtained using a 3dMD torso system (3Q Technologies Inc., Atlanta, GA). Two different types (contoured and line-of-sight distances) of a total of nine distances were computed from 3D images of each participant. Each participant was photographed twice, first without fiducial points marked (referred to as unmarked image) and second with fiducial points marked prior to imaging (referred to as marked image). Stereophotogrammetry was compared to traditional direct anthropometry, in which measurements were taken with a tape measure on participants. Three statistical analyses were used to evaluate the agreement between stereophotogrammetry and direct anthropometry. Seven out of nine distances showed excellent agreement between stereophotogrammetry and direct anthropometry (both marked and unmarked images). In addition, stereophotogrammetry from the unmarked image was equivalent to that of the marked image (both line-of-sight and contoured distances). A lower level of agreement was observed for some measures because of difficulty in localizing more vaguely defined fiducial points, such as lowest visible point of breast mound, and inability of the imaging system in capturing areas obscured by the breast, such as the inframammary fold. Stereophotogrammetry from 3D images obtained from the 3dMD torso system is effective for quantifying breast morphology. Tools for surgical planning and evaluation based on stereophotogrammetry have the potential to improve breast surgery outcomes.

THE SHAPE AND PROFILE OF THE MILKY WAY HALO AS SEEN BY THE CANADA-FRANCE-HAWAII TELESCOPE LEGACY SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sesar, Branimir; Ivezic, Zeljko; Juric, Mario, E-mail: bsesar@astro.caltech.edu

2011-04-10

We use Canada-France-Hawaii Telescope Legacy Survey data for 170 deg{sup 2}, recalibrated and transformed to the Sloan Digital Sky Survey ugri photometric system, to study the distribution of near-turnoff main-sequence stars in the Galactic halo along four lines of sight to heliocentric distances of {approx}35 kpc. We find that the halo stellar number density profile becomes steeper at Galactocentric distances greater than R{sub gal} {approx} 28 kpc, with the power-law index changing from n{sub inner} = -2.62 {+-} 0.04 to n{sub outer} = -3.8 {+-} 0.1. In particular, we test a series of single power-law models and find them tomore » be strongly disfavored by the data. The parameters for the best-fit Einasto profile are n = 2.2 {+-} 0.2 and R{sub e} = 22.2 {+-} 0.4 kpc. We measure the oblateness of the halo to be q {identical_to} c/a = 0.70 {+-} 0.01 and detect no evidence of it changing across the range of probed distances. The Sagittarius stream is detected in the l = 173 deg. and b = -62 deg. direction as an overdensity of [Fe/H] {approx} -1.5 dex stars at R{sub gal} {approx} 32 kpc, providing a new constraint for the Sagittarius stream and dark matter halo models. We also detect the Monoceros stream as an overdensity of [Fe/H] > -1.5 dex stars in the l = 232 deg. and b = 26 deg. direction at R{sub gal} {approx}< 25 kpc. In the two sight lines where we do not detect significant substructure, the median metallicity is found to be independent of distance within systematic uncertainties ([Fe/H] {approx} -1.5 {+-} 0.1 dex).« less

IMPROVING THE PRECISION OF TIME-DELAY COSMOGRAPHY WITH OBSERVATIONS OF GALAXIES ALONG THE LINE OF SIGHT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greene, Zach S.; Suyu, Sherry H.; Treu, Tommaso

2013-05-01

In order to use strong gravitational lens time delays to measure precise and accurate cosmological parameters the effects of mass along the line of sight must be taken into account. We present a method to achieve this by constraining the probability distribution function of the effective line-of-sight convergence {kappa}{sub ext}. The method is based on matching the observed overdensity in the weighted number of galaxies to that found in mock catalogs with {kappa}{sub ext} obtained by ray-tracing through structure formation simulations. We explore weighting schemes based on projected distance, mass, luminosity, and redshift. This additional information reduces the uncertainty ofmore » {kappa}{sub ext} from {sigma}{sub {kappa}} {approx} 0.06 to {approx}0.04 for very overdense LOSs like that of the system B1608+656. For more common LOSs, {sigma}{sub {kappa}} is reduced to {approx}<0.03, corresponding to an uncertainty of {approx}< 3% on distance. This uncertainty has comparable effects on cosmological parameters to that arising from the mass model of the deflector and its immediate environment. Photometric redshifts based on g, r, i and K photometries are sufficient to constrain {kappa}{sub ext} almost as well as with spectroscopic redshifts. As an illustration, we apply our method to the system B1608+656. Our most reliable {kappa}{sub ext} estimator gives {sigma}{sub {kappa}} = 0.047 down from 0.065 using only galaxy counts. Although deeper multiband observations of the field of B1608+656 are necessary to obtain a more precise estimate, we conclude that griK photometry, in addition to spectroscopy to characterize the immediate environment, is an effective way to increase the precision of time-delay cosmography.« less

Measurements of coronal Faraday rotation at 4.6 R {sub ☉}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kooi, Jason E.; Fischer, Patrick D.; Buffo, Jacob J.

2014-03-20

Many competing models for the coronal heating and acceleration mechanisms of the high-speed solar wind depend on the solar magnetic field and plasma structure in the corona within heliocentric distances of 5 R {sub ☉}. We report on sensitive Very Large Array (VLA) full-polarization observations made in 2011 August, at 5.0 and 6.1 GHz (each with a bandwidth of 128 MHz) of the radio galaxy 3C 228 through the solar corona at heliocentric distances of 4.6-5.0 R {sub ☉}. Observations at 5.0 GHz permit measurements deeper in the corona than previous VLA observations at 1.4 and 1.7 GHz. These Faradaymore » rotation observations provide unique information on the magnetic field in this region of the corona. The measured Faraday rotation on this day was lower than our a priori expectations, but we have successfully modeled the measurement in terms of observed properties of the corona on the day of observation. Our data on 3C 228 provide two lines of sight (separated by 46'', 33,000 km in the corona). We detected three periods during which there appeared to be a difference in the Faraday rotation measure between these two closely spaced lines of sight. These measurements (termed differential Faraday rotation) yield an estimate of 2.6-4.1 GA for coronal currents. Our data also allow us to impose upper limits on rotation measure fluctuations caused by coronal waves; the observed upper limits were 3.3 and 6.4 rad m{sup –2} along the two lines of sight. The implications of these results for Joule heating and wave heating are briefly discussed.« less

A Review of the Geographical Distribution and Habitat of the Atlantic Humpback Dolphin (Sousa teuszii).

PubMed

Weir, Caroline R; Collins, Tim

2015-01-01

Understanding of the distributional ecology of the Atlantic humpback dolphin (Sousa teuszii) has been hampered by a lack of systematic and consistent sampling effort. The only comprehensive species distribution review was published in 2004; since then a considerable amount of novel information has emerged. We compiled 853 sighting, capture and specimen records of the species, and produced global and regional distribution maps. Of the 830 records where year was available, 63.1% dated from ≥2005 and confirm a contemporary occurrence in six marine ecoregions and 11 countries: Western Sahara, Mauritania, Senegal, Gambia, Guinea-Bissau, Guinea, Benin, Cameroon, Gabon, Congo Republic and Angola. Additionally, Togo is a recently confirmed range state. Group sizes ranged from 1 to 45 animals, with small groups of 1 to 10 animals comprising 65% of the sightings. Similarities were noted in the regions inhabited by Atlantic humpback dolphins across their range, particularly an occurrence in relatively shallow (predominantly ≤20 m) depths, in warm waters (average SSTs of 15.8-31.8°C) and in dynamic habitat strongly influenced by tidal patterns. These conditions occur in various habitats occupied by the species, including estuarine systems, open coasts, archipelagos, tidal mud-flats and sheltered bays. Sightings were recorded at distances of 13 m to 12.8 km (mean of 573 m) from land, indicating that the species occurs several kilometres from shore when suitable shallow habitat is present. The Atlantic humpback dolphin may be a 'nearshore' species based on oceanographic definitions incorporating water depth, wave action and sedimentation rather than on spatial distance from the coast. © 2015 Elsevier Ltd All rights reserved.

Planetary Nebulae and their parent stellar populations. Tracing the mass assembly of M87 and Intracluster light in the Virgo cluster core

NASA Astrophysics Data System (ADS)

Arnaboldi, Magda; Longobardi, Alessia; Gerhard, Ortwin

2016-08-01

The diffuse extended outer regions of galaxies are hard to study because they are faint, with typical surface brightness of 1% of the dark night sky. We can tackle this problem by using resolved star tracers which remain visible at large distances from the galaxy centers. This article describes the use of Planetary Nebulae as tracers and the calibration of their properties as indicators of the star formation history, mean age and metallicity of the parent stars in the Milky Way and Local Group galaxies. We then report on the results from a deep, extended, planetary nebulae survey in a 0.5 deg2 region centered on the brightest cluster galaxy NGC 4486 (M87) in the Virgo cluster core, carried out with SuprimeCam@Subaru and FLAMES-GIRAFFE@VLT. Two planetary nebulae populations are identified out to 150 kpc distance from the center of M87. One population is associated with the M87 halo and the second one with the intracluster light in the Virgo cluster core. They have different line-of-sight velocity and spatial distributions, as well as different planetary nebulae specific frequencies and luminosity functions. The intracluster planetary nebulae in the surveyed region correspond to a luminosity of four times the luminosity of the Large Magellanic Cloud. The M87 halo planetary nebulae trace an older, more metal-rich, parent stellar population. A substructure detected in the projected phase-space of the line-of-sight velocity vs. major axis distance for the M87 halo planetary nebulae provides evidence for the recent accretion event of a satellite galaxy with luminosity twice that of M33. The satellite stars were tidally stripped about 1 Gyr ago, and reached apocenter at a major axis distance of 60-90 kpc from the center of M87. The M87 halo is still growing significantly at the distances where the substructure is detected.

OB Stars and Cepheids From the Gaia TGAS Catalogue: Test of their Distances and Proper Motions

NASA Astrophysics Data System (ADS)

Bobylev, Vadim V.; Bajkova, Anisa T.

2017-12-01

We consider young distant stars from the Gaia TGAS catalog. These are 250 classical Cepheids and 244 OB stars located at distances up to 4 kpc from the Sun. These stars are used to determine the Galactic rotation parameters using both trigonometric parallaxes and proper motions of the TGAS stars. In this case the considered stars have relative parallax errors less than 200%. Following the well-known statistical approach, we assume that the kinematic parameters found from the line-of-sight velocities Vr are less dependent on errors of distances than the found from the velocity components Vl. From values of the first derivative of the Galactic rotation angular velocity '0, found from the analysis of velocities Vr and Vl separately, the scale factor of distances is determined.We found that from the sample of Cepheids the scale of distances of the TGAS should be reduced by 3%, and from the sample of OB stars, on the contrary, the scale should be increased by 9%.

Mobile robot trajectory tracking using noisy RSS measurements: an RFID approach.

PubMed

Miah, M Suruz; Gueaieb, Wail

2014-03-01

Most RF beacons-based mobile robot navigation techniques rely on approximating line-of-sight (LOS) distances between the beacons and the robot. This is mostly performed using the robot's received signal strength (RSS) measurements from the beacons. However, accurate mapping between the RSS measurements and the LOS distance is almost impossible to achieve in reverberant environments. This paper presents a partially-observed feedback controller for a wheeled mobile robot where the feedback signal is in the form of noisy RSS measurements emitted from radio frequency identification (RFID) tags. The proposed controller requires neither an accurate mapping between the LOS distance and the RSS measurements, nor the linearization of the robot model. The controller performance is demonstrated through numerical simulations and real-time experiments. ©2013 Published by ISA. All rights reserved.

Effectiveness of transverse grooves in rigid pavement

NASA Astrophysics Data System (ADS)

Gurney, G. F.; Bryden, J. E.

1982-10-01

Transverse grooves were installed at 11 intersection approaches on worn rigid pavement to reduce a high rate of wet road accidents. In most cases, accident reductions were experienced only at intersections with multiple negative operational characteristics, including higher approach speeds, limited sight distances, and frequent vehicle stopping for turns or stop signs. Intersections with no more than one negative characteristic generally did not benefit from grooving.

Seen areas and the distribution of fires about a lookout

Treesearch

Romain M. Mees

1978-01-01

From the location of a fire lookout and the sites of past fires within a given radius about a lookout, an estimate of the fire distribution with respect to distance from the lookout can be obtained. The estimated distribution can include all fires located within a given number of feet below the last maximum line of sight from the lookout. Seen areas for the same...

Seven Experiment Designs Addressing Problems of Safety and Capacity on Two-Lane Rural Highways : Volume 8. Experimental Design and Evaluate Remedial Aids for Intersections with Inadequate Sight Distance

DOT National Transportation Integrated Search

2007-01-01

Americans lose 3.7 billion hours and 2.3 billion gallons of fuel every year sitting in traffic jams, and nearly 24 percent of non-recurring freeway delay, or about 482 million hours, is attributed to work zones. To combat the country's growing transp...

Available sight distance on existing highways: Meeting stopping sight distance requirements of an aging population.

PubMed

Gargoum, Suliman A; Tawfeek, Mostafa H; El-Basyouny, Karim; Koch, James C

2018-03-01

An important element of highway design is ensuring that the available sight distance (ASD) on a highway meets driver needs. For instance, if the ASD at any point on a highway is less than the distance required to come to a complete stop after seeing a hazard (i.e. Stopping Sight Distance (SSD)), the driver will not be able to stop in time to avoid a collision. SSD is function of a number of variables which vary depending on the driver, the vehicle driven and surface conditions; examples of such variables include a driver's perception reaction time or PRT (i.e. the time required by the driver to perceive and react to a hazard) and the deceleration rate of the vehicle. Most design guides recommend deterministic values for PRT and deceleration rates. Although these values may serve the needs of the average driver, they may not satisfy the needs of drivers with limited abilities. In other words, even if the ASD exceeds required SSD defined in the design guide, it might not always satisfy the needs of all drivers. While it is impossible to design roads that satisfy the needs of all drivers, the fact that most developed countries suffer from an aging population, means that the number of old drivers on our roads is expected to increase. Since a large proportion of old drivers often have limited abilities, it is expected that the general population of drivers with limited abilities on our roads will increase with time. Accordingly, more efforts are required to ensure that existing road infrastructure is prepared to handle such a change. This paper aims to explore the extent to which ASD on highways satisfies the needs of drivers with limited abilities. The paper first develops MATLAB and Python codes to automatically estimate the ASD on highway point cloud data collected using Light Detection and Ranging (LiDAR) remote sensing technology. The developed algorithms are then used to estimate ASD on seven different crash prone segments in the Province of Alberta, Canada and the ASD is compared to the required SSD on each highway. Three different levels of SSD are defined (SSD for drivers with limited ability, AASHTOs SSD requirements and SSD for drivers with high skill). The results show that, when compared to SSD requirements which integrate limitations in cognitive abilities, a substantial portion of the analyzed segments do not meet the requirements (up to 20%). Similarly, when compared to AASHTO's SSD requirements, up to 6% of the analyzed segments do not meet the requirements. In an attempt to explore the effects of such design limitations on safety, the paper also explores crash rates in noncompliant regions (i.e. regions that do not provide sufficient SSD) and compares them to crash rates in compliant regions. On average, it was found that noncompliant regions experience crash rates that are 2.15 and 1.25 times higher than compliant regions for AASHTO's SSD requirements and those integrating driver limitations, respectively. Furthermore, the study found that a significantly higher proportion of drivers involved in collisions in the noncompliant regions were old drivers. Copyright © 2018 Elsevier Ltd. All rights reserved.

Spatiotemporal characteristics of motor actions by blind long jump athletes

PubMed Central

Torralba, Miguel Angel; Padullés, José María; Losada, Jose Luis; López, Jose Luis

2017-01-01

Background Blind people depend on spatial and temporal representations to perform activities of daily living and compete in sport. Objective The aim of this study is to determine the spatiotemporal characteristics of long jumps performed by blind athletes and compare findings with those reported for sighted athletes. Methods We analysed a sample of 12 male athletes competing in the F11 Long Jump Finals at the Paralympic Games in London 2012. Performances were recorded using four high-speed cameras, and speeds were measured using a radar speed gun. The images were processed using validated image analysis software. Results The long jump run-up is shorter in blind athletes than in sighted athletes. We observed statistically significant differences for body centre of mass velocity and an increase in speed over the last three strides prior to take-off, contrasting with reports for sighted athletes and athletes with less severe visual impairment, who maintain or reduce their speed during the last stride. Stride length for the last three strides was the only spatial characteristic that was not significantly associated with effective jump distance. Blind long jumpers extend rather than shorten their last stride. Contact time with the take-off board is longer than that reported for sighted athletes. Conclusion The actions of blind long jumpers, unlike those without disabilities, do not vary their leg actions during the final runway approach for optimal placement on the take-off board. PMID:29018542

Synthesis of Nonlinear Guidance Laws for Missiles with Uncertain Dynamics

DTIC Science & Technology

2007-11-01

and Astronautics, Progress in Astronautics and Aeronautics, Volume 199, 2002. 2. Gurfil , M. Jodorkovsky and M. Guelman, Neoclassical Guidance for...658-666, July-August 2002. 19. P. Gurfil , “Robust Guidance for Electro-Optical Missiles,” IEEE Transactions on Aerospace and Electronic Systems, Vol...edition, Upper Saddle River, NJ: Prentice-Hall, 2002. 23. P. Gurfil , ”Zero-Miss Distance Guidance Law Based on Line-of-Sight Rate Measuremenbt Only

Precision targeting in guided munition using IR sensor and MmW radar

NASA Astrophysics Data System (ADS)

Sreeja, S.; Hablani, H. B.; Arya, H.

2015-10-01

Conventional munitions are not guided with sensors and therefore miss the target, particularly if the target is mobile. The miss distance of these munitions can be decreased by incorporating sensors to detect the target and guide the munition during flight. This paper is concerned with a Precision Guided Munition(PGM) equipped with an infrared sensor and a millimeter wave radar [IR and MmW, for short]. Three-dimensional flight of the munition and its pitch and yaw motion models are developed and simulated. The forward and lateral motion of a target tank on the ground is modeled as two independent second-order Gauss-Markov process. To estimate the target location on the ground and the line-of-sight rate to intercept it an Extended Kalman Filter is composed whose state vector consists of cascaded state vectors of missile dynamics and target dynamics. The line-of-sight angle measurement from the infrared seeker is by centroiding the target image in 40 Hz. The centroid estimation of the images in the focal plane is at a frequency of 10 Hz. Every 10 Hz, centroids of four consecutive images are averaged, yielding a time-averaged centroid, implying some measurement delay. The miss distance achieved by including by image processing delays is 1:45m.

Mapping the X-shaped Milky Way Bulge

NASA Astrophysics Data System (ADS)

Saito, R. K.; Zoccali, M.; McWilliam, A.; Minniti, D.; Gonzalez, O. A.; Hill, V.

2011-09-01

We analyzed the distribution of the red clump (RC) stars throughout the Galactic bulge using Two Micron All Sky Survey data. We mapped the position of the RC in 1 deg2 fields within the area |l| <= 8fdg5 and 3fdg5 <= |b| <= 8fdg5, for a total of 170 deg2. The single RC seen in the central area splits into two components at high Galactic longitudes in both hemispheres, produced by two structures at different distances along the same line of sight. The X-shape is clearly visible in the Z-X plane for longitudes close to the l = 0° axis. Crude measurements of the space densities of RC stars in the bright and faint RC populations are consistent with the adopted RC distances, providing further supporting evidence that the X-structure is real, and that there is approximate front-back symmetry in our bulge fields. We conclude that the Milky Way bulge has an X-shaped structure within |l| <~ 2°, seen almost edge-on with respect to the line of sight. Additional deep near-infrared photometry extending into the innermost bulge regions combined with spectroscopic data is needed in order to discriminate among the different possibilities that can cause the observed X-shaped structure.

Distribution of black-tailed jackrabbit habitat determined by GIS in southwestern Idaho

USGS Publications Warehouse

Knick, Steven T.; Dyer, D.L.

1997-01-01

We developed a multivariate description of black-tailed jackrabbit (Lepus californicus) habitat associations from Geographical Information Systems (GIS) signatures surrounding known jackrabbit locations in the Snake River Birds of Prey National Conservation Area (NCA), in southwestern Idaho. Habitat associations were determined for characteristics within a 1-km radius (approx home range size) of jackrabbits sighted on night spotlight surveys conducted from 1987 through 1995. Predictive habitat variables were number of shrub, agriculture, and hydrography cells, mean and standard deviation of shrub patch size, habitat richness, and a measure of spatial heterogeneity. In winter, jackrabbits used smaller and less variable sizes of shrub patches and areas of higher spatial heterogeneity when compared to summer observations (P 0.05), differed significantly between high and low population phase. We used the Mahalanobis distance statistic to rank all 50-m cells in a 440,000-ha region relative to the multivariate mean habitat vector. On verification surveys to test predicted models, we sighted jackrabbits in areas ranked close to the mean habitat vector. Areas burned by large-scale fires between 1980 and 1992 or in an area repeatedly burned by military training activities had greater Mahalanobis distances from the mean habitat vector than unburned areas and were less likely to contain habitats used by jackrabbits.

Depth Perception in Space (Artist's Concept)

NASA Technical Reports Server (NTRS)

2007-01-01

This artist's concept shows how astronomers use the unique orbit of NASA's Spitzer Space Telescope and a depth-perceiving trick called parallax to determine the distance of dark planets, black holes and failed stars that lurk invisibly among us. These objects do not produce light, and are too faint to detect from Earth. However, astronomers can deduce their presence from the way they affect the light from background objects. When such a dark body passes in front of a bright star, its gravity warps the path of the star's light and causes it to brighten -- this process is called gravitational microlensing.

By comparing the 'peak brightness' of the microlensing event from two perspectives -- Earth and Spitzer -- scientists can determine how far away the dark object is. Peak brightness is the moment when the observer, the dark object and background star are most closely aligned.

Humans naturally use parallax to determine distance -- this is commonly referred to as depth perception. In the case of humans, each eye sees the position of an object differently. The brain takes each eye's perspective, and instantaneously calculates how far away the object is. In space, astronomers can use the same trick to determine the distance of an invisible dark object.

In this illustration, the dark object is the moving black ball between Earth, Spitzer and our neighboring galaxy the Small Magellanic Cloud (SMC; bottom right).

To determine the object's distance, astronomers observe the microlensing event at its 'peak brightness' from Earth when the dark object crosses our line-of-sight (dashed line) to a given star in the SMC. This represents one perspective, like looking at an object with only your left eye.

To get the other 'right eye' perspective, astronomers also observe the peak brightness with Spitzer when the object later moves through its line-of-sight. Because astronomers know the exact distance between Earth and Spitzer, they can determine the dark body's speed by timing how long it took for Spitzer to see peak brightness after astronomers observed the event on Earth. Using trigonometric equations and graphs to do the 'brain's' job, scientists can infer the dark body's distance.

The scales in this diagram are greatly exaggerated for clarity. The distance between Spitzer and the Earth is miniscule in comparison to the distance to the dark object and SMC. Since microlensing events require extremely precise alignments, even such a tiny separation is enough to measure these objects out to tremendous distances.

Long range thermal weapon sights for the German future infantryman program IdZ

NASA Astrophysics Data System (ADS)

Breiter, Rainer; Ihle, Tobias; Mauk, Karl-Heinz; Münzberg, Mario; Rode, Werner

2007-04-01

In December 2004 AIM started the series production of the HuntIR long range thermal weapon sight. The sight is fielded in the Germany Future Infantryman (IdZ) basic system and since that time in continuous service in various out of area missions with German participation. For very long identification ranges >1500m cooled technology still outperforms uncooled sights, even with respect to smaller size and lower weight because the typical F/1 design of uncooled systems overcompensates cooler weight for focal length >175mm. The HuntIR sight is therefore based on a cooled MWIR detection module for long range battlefield surveillance and target engagement. The device specifically is a perfect match to state of the art small arms like 0.50 cal sniper rifles or crew served weapons like the 40mm high velocity grenade machine gun (GMG) which provide engagement ranges >1500m and need an adequate sight performance beyond that. A recent modification of HuntIR was done to provide a wider field of view for improved situation awareness in urban operations and specifically to allow the engagement of the 40mm GMG in ranges between 250-1200m. The qualification tests of the sight by the German infantry were successfully completed mid 2006. To match the demand of the follow-up program IdZ-ES additional components have to be integrated. Most important are a laser range finder (LRF), 3 axis digital magnetic compass (DMC) and a wireless data link. LRF and DMC together with a highly sophisticated fire control computer provide improved first round hit probability, the DMC additionally improves the fire control in any case of steep trajectories or for pronounced ballistic trajectories to avoid any need to precisely level the GMG. This new sight is done under the brand name RangIR. An important additional feature is the interface for air burst ammunition (ABM). The optical distance is measured by the LRF, the fire control computer accurately evaluates the trajectory under the given angle, muzzle velocity, temperature and range conditions to define the time-of-flight. This fully integrated IR fire control system is available mid 2007. The development phase of the IdZES program is under contract, series deliveries expected in 2009. The RangIR will see some specific modifications for the link and a man machine interface to control the whole IdZ-ES system components ergonomically from the weapon with optimized power supply concepts to minimize the number of batteries, chargers etc.

Prelinguistic human infants and great apes show different communicative strategies in a triadic request situation.

PubMed

Gretscher, Heinz; Tempelmann, Sebastian; Haun, Daniel B M; Liebal, Katja; Kaminski, Juliane

2017-01-01

In the present research, we investigate the communicative strategies of 20 month old human infants and great apes when requesting rewards from a human experimenter. Infants and apes both adapted their signals to the attentional state of the experimenter as well as to the location of the reward. Yet, while infants frequently positioned themselves in front of the experimenter and pointed towards a distant reward, apes either remained in the experimenter's line of sight and pointed towards him or moved out of sight and pointed towards the reward. Further, when pointing towards a reward that was placed at a distance from the experimenter, only the infants, and not the apes, took the experimenter's attentional state into account. These results demonstrate that prelinguistic human infants and nonhuman apes use different means when guiding others' attention to a location; indicating that differing cognitive mechanisms may underlie their pointing gestures.

Kalman Filter Input Processor for Boresight Calibration

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry; Kruizinga, Gerhard; Paik, Meegyeong; Yuan, Dah-Ning; Asmar, Sami W.

2014-01-01

Ka-band ranging provides the phase center (PC) to phase center range, which needs to be converted to the center of mass (CM) to center of mass range. Nominally, both PC and CM lie on the line connecting the spacecraft GRAIL A and GRAIL B. In this case, the conversion should be done simply by adding the CM-to-PC distance L to the measured range for both spacecraft. However, due to various technical reasons, such as displacement of the true CM from its nominal position in the SRF, or spacecraft attitude fluctuations, the PC and CM define a unit vector that may be different from the nominal line of sight. The objectives of the software are to determine the actual line of sight direction for each spacecraft and correct the previously recorded range data, and to provide instructions for how to maneuver each spacecraft to make necessary attitude corrections.

Some rates of geomorphological processes

USGS Publications Warehouse

Leopold, Luna Bergere; Emmett, William W.

1972-01-01

This brief report summarizes three sets of measurement data on certain processes.The first concerns the rate of movement of soil on hillslopes, especially by mass movement or slow gravitational creep. The results are abstracted from an unpublished manuscript by the junior author who reports on the measurements which Leopold began 10 or more years ago and to which in more recent years Emmett has added new sites and has carried on the annual remeasurement. The results are those from "mass-movement lines", which consist of a series of pins or iron rods, 10 inches (25 cm) long driven vertically into the ground along a straight line-of-sight, secured at each end with stiff iron posts. The Survey consists of setting a theodolite over one of the end bench marks and orienting on the other. The distance of each individual pin from the line of sight is recorded. Resurveys are usually made annually.

Precision Timing of PSR J0437-4715: An Accurate Pulsar Distance, a High Pulsar Mass, and a Limit on the Variation of Newton's Gravitational Constant

NASA Astrophysics Data System (ADS)

Verbiest, J. P. W.; Bailes, M.; van Straten, W.; Hobbs, G. B.; Edwards, R. T.; Manchester, R. N.; Bhat, N. D. R.; Sarkissian, J. M.; Jacoby, B. A.; Kulkarni, S. R.

2008-05-01

Analysis of 10 years of high-precision timing data on the millisecond pulsar PSR J0437-4715 has resulted in a model-independent kinematic distance based on an apparent orbital period derivative, dot Pb , determined at the 1.5% level of precision (Dk = 157.0 +/- 2.4 pc), making it one of the most accurate stellar distance estimates published to date. The discrepancy between this measurement and a previously published parallax distance estimate is attributed to errors in the DE200 solar system ephemerides. The precise measurement of dot Pb allows a limit on the variation of Newton's gravitational constant, |Ġ/G| <= 23 × 10-12 yr-1. We also constrain any anomalous acceleration along the line of sight to the pulsar to |a⊙/c| <= 1.5 × 10-18 s-1 at 95% confidence, and derive a pulsar mass, mpsr = 1.76 +/- 0.20 M⊙, one of the highest estimates so far obtained.

Nuclear Weapons Effects Mitigation Techniques

DTIC Science & Technology

1982-06-01

ELF ) into the ultra-high (UHF) frequeniese, with much of Its energy concentrated In frequenrv ranges (high frequency (IF) into UHF) employed by Army...tactical Communications equipment. It Is of concern because the damage and upset it causes can occur Rt distances from the burst far beyond where...radiation is scattered from all directions, most of’ it comes from direct line-of-sight to the fireball. Therefore, the flat earth cover of an underground

Discrimination Between Child and Adult Forms Using Radar Frequency Signature Analysis

DTIC Science & Technology

2013-03-14

Distances. This sensor poses no risk to human subjects or persons operating the equipment. The 88 th Medical Group Bio -Environmental Safety...method of remotely characterizing human activity. Unlike optical sensors , radar systems need not rely upon line-of-sight or good weather to perform well...and in monitoring vital signs through chemical or bio - logical protection suits. These military applications have seen research as early as the mid

Experimental evaluation of LED-based solar blind NLOS communication links.

PubMed

Chen, Gang; Abou-Galala, Feras; Xu, Zhengyuan; Sadler, Brian M

2008-09-15

Experimental results are reported demonstrating non-line of sight short-range ultraviolet communication link losses, and performance of photon counting detectors, operating in the solar blind spectrum regime. We employ light emitting diodes with divergent beams, a solar blind filter, and a wide field-of-view detector. Signal and noise statistics are characterized, and receiver performance is demonstrated. The effects of transmitter and receiver elevation angles, separation distance, and path loss are included.

Micro-Doppler extraction of a small UAV in a non-line-of-sight urban scenario

NASA Astrophysics Data System (ADS)

Gustavsson, Magnus; Andersson, Åsa; Johansson, Tommy; Jonsson, Rolf; Karlsson, Nils; Nilsson, Stefan

2017-05-01

The appearance of small UAVs on the commercial market poses a real threat to both civilian safety and to military operations. In open terrain a radar can detect and track even small UAVs at long distances. In an urban environment with limited line-of-sight and strong static and non-static background, this capability can be severely reduced. The radar cross section of these UAVs are normally small compared to the background. However, the rotors of the UAVs produce a characteristic micro-Doppler signature that can be exploited for detection and classification. In this paper, we investigate in an experimental set-up whether it is possible in the radar non-line-of-sight to retrieve the micro-Doppler signature of the UAV rotors. This is done by exploring up to three multipath bounces in the measured signal. The measurements were made with a semi-monostatic single receiver-transmitter radar system operating at X-band in a pulsed single frequency mode. The radar response of the UAV, with plastic and metallic rotors, was measured at several positions inside a 4 m wide corridor with metallic walls. In this paper, data from one line-of-sight and two non-line-ofsight positions are presented. Results show that we are able to detect the micro-Doppler of the rotors and to retrieve the number of revolutions per minute, for both rotor types. Free space Finite-Difference Time-Domain calculations have also been performed on a CAD-model of the UAV rotor to determine the optimal choice of polarization and the short-time Fourier transform filter length.

Low density of neutral hydrogen and helium in the local interstellar medium: Extreme Ultraviolet Explorer photometry of the Lyman continuum of the hot white dwarfs MCT 0501-2858, MCT 0455-2812, HZ 43, and GD 153

NASA Technical Reports Server (NTRS)

Vennes, Stephane; Dupuis, Jean; Bowyer, Stuart; Fontaine, Gilles; Wiercigroch, Alexandria; Jelinsky, Patrick; Wesemael, Francois; Malina, Roger

1994-01-01

The first comprehensive sky survey of the extreme ultraviolet (EUV) spectral range performed by the Extreme Ultraviolet Explorer (EUVE) has uncovered a handful of very bright sources at wavelengths longer than the He I 504 A photoionization edge. Among these objects are four white dwarfs with exceptionally low interstellar medium (ISM) column densities along the line of sight. Analysis of EUV photometry of the He-rich DO white dwarf MCT 0501-2858 and the H-rich DA white dwarf MCT 0455-2812 along one line of sight and of the DA white dwarfs HZ 43 and GD 153 near the north Galactic pole indicates that the overall minimum column density of the neutral material centered on the Sun is N(H I) = 0.5-1.0 x 10(exp 18)/sq cm. In the case of MCT 0501-2858, EUV photometric measurements provide a clear constraint to the effective temperature (60,000-70,000 K). Given these neutral hydrogen columns, the actual contribution to the density of neutral species from the immediate solar environment (the 'local fluff') would only cover a distance of approximately equals 2-3 pc (assuming an average density n(H I) = 0.1/cu cm) leaving these lines of sight almost entirely within the hot phase of the ISM. A preliminary examination of the complete EUVE long-wavelength survey indicates that these lines of sight are exceptional and set a minimum column density in the solar environment.

An intelligent rollator for mobility impaired persons, especially stroke patients.

PubMed

Hellström, Thomas; Lindahl, Olof; Bäcklund, Tomas; Karlsson, Marcus; Hohnloser, Peter; Bråndal, Anna; Hu, Xiaolei; Wester, Per

2016-07-01

An intelligent rollator (IRO) was developed that aims at obstacle detection and guidance to avoid collisions and accidental falls. The IRO is a retrofit four-wheeled rollator with an embedded computer, two solenoid brakes, rotation sensors on the wheels and IR-distance sensors. The value reported by each distance sensor was compared in the computer to a nominal distance. Deviations indicated a present obstacle and caused activation of one of the brakes in order to influence the direction of motion to avoid the obstacle. The IRO was tested by seven healthy subjects with simulated restricted and blurred sight and five stroke subjects on a standardised indoor track with obstacles. All tested subjects walked faster with intelligence deactivated. Three out of five stroke patients experienced more detected obstacles with intelligence activated. This suggests enhanced safety during walking with IRO. Further studies are required to explore the full value of the IRO.

Polarization vision seldom increases the sighting distance of silvery fish.

PubMed

Johnsen, Sönke; Gagnon, Yakir L; Marshall, N Justin; Cronin, Thomas W; Gruev, Viktor; Powell, Samuel

2016-08-22

Although the function of polarization vision, the ability to discern the polarization characteristics of light, is well established in many terrestrial and benthic species, its purpose in pelagic species (squid and certain fish and crustaceans) is poorly understood [1]. A long-held hypothesis is that polarization vision in open water is used to break the mirror camouflage of silvery fish, as biological mirrors can change the polarization of reflected light [2,3]. Although, the addition of polarization information may increase the conspicuousness of silvery fish at close range, direct evidence that silvery fish - or indeed any pelagic animal - are visible at longer distances using polarization vision rather than using radiance (i.e. brightness) vision is lacking. Here we show, using in situ polarization imagery and a new visual detection model, that polarization vision does not in fact appear to allow viewers to see silvery fish at greater distances. Copyright © 2016 Elsevier Ltd. All rights reserved.

A model for the Lin-Shu type density-wave structure of our Galaxy: Line-of-sight and transverse-longitudinal velocities of 242 optically visible open clusters

NASA Astrophysics Data System (ADS)

Griv, E.; Jiang, I.-G.

2015-02-01

In this paper, the fourth in a series, we examine again one of the implications of the Lin-Shu density-wave theory, specifically, the noncircular systematic motion of the Galactic objects. Our previous investigation is extended by analyzing simultaneously both the line-of-sight and transversal velocities of a sample of open clusters for which velocities, distances and ages are available. The ordinary equations of the Oort-Lindblad theory of galactic differential rotation are used. The minor effects caused by the two-dimensional tightly-wound density waves are also taken into account. The published data of 242 currently known optically visible clusters having distances r<3 kpc from the Sun and -200 < z <200 pc from the Galactic plane, and ages 2 × 108 < t < 2 × 109 yr are collected from Dias et al. (2014), excluding extremely far, high-velocity, young and old objects in our fitting. The most noteworthy result is the fact that the parameters of Lin-Shu type density waves estimated from two independent line-of-sight and transversal along the Galactic longitude velocities are nearly equal. We argue that the resemblance of these Galactic wave structures is so remarkable that no doubt is felt as to the theory's truth with respect to these data. The results obtained allow us to conclude that several low-m trailing density-wave patterns with different number of spiral arms m (say, m=1, 2, 3, and 4), pitch angles (about 5o, 8o, 11o, and 14o, respectively) and amplitudes of the perturbed gravitational potential may coexist in the Galaxy. The latter suggests the asymmetric multiarm, not well-organized (``flocculent'') spiral structure of the system. In memory of Professors Alexei M. Fridman (1940-2010) and Chi Yuan (1937-2008)

Estimating the spatial position of marine mammals based on digital camera recordings

PubMed Central

Hoekendijk, Jeroen P A; de Vries, Jurre; van der Bolt, Krissy; Greinert, Jens; Brasseur, Sophie; Camphuysen, Kees C J; Aarts, Geert

2015-01-01

Estimating the spatial position of organisms is essential to quantify interactions between the organism and the characteristics of its surroundings, for example, predator–prey interactions, habitat selection, and social associations. Because marine mammals spend most of their time under water and may appear at the surface only briefly, determining their exact geographic location can be challenging. Here, we developed a photogrammetric method to accurately estimate the spatial position of marine mammals or birds at the sea surface. Digital recordings containing landscape features with known geographic coordinates can be used to estimate the distance and bearing of each sighting relative to the observation point. The method can correct for frame rotation, estimates pixel size based on the reference points, and can be applied to scenarios with and without a visible horizon. A set of R functions was written to process the images and obtain accurate geographic coordinates for each sighting. The method is applied to estimate the spatiotemporal fine-scale distribution of harbour porpoises in a tidal inlet. Video recordings of harbour porpoises were made from land, using a standard digital single-lens reflex (DSLR) camera, positioned at a height of 9.59 m above mean sea level. Porpoises were detected up to a distance of ∽3136 m (mean 596 m), with a mean location error of 12 m. The method presented here allows for multiple detections of different individuals within a single video frame and for tracking movements of individuals based on repeated sightings. In comparison with traditional methods, this method only requires a digital camera to provide accurate location estimates. It especially has great potential in regions with ample data on local (a)biotic conditions, to help resolve functional mechanisms underlying habitat selection and other behaviors in marine mammals in coastal areas. PMID:25691982

Blazars: The accelerating inner jet model.

NASA Astrophysics Data System (ADS)

Georganopoulos, M.; Marscher, A. P.

1996-05-01

The standard interpretation of the nonthermal continuum radiation of blazars from radio to gamma -rays is thought to be synchrotron and inverse Compton radiation from a relativistic jet. The inner jet of a blazar is the section of the jet that connects the central engine with the VLBI core of the radio jet. This is a small (la 1 pc) region where the jet is formed, collimated and accelerated to speeds close to that of light. In the accelerating inner jet model ultrarelativistic plasma is generated continuously near the central engine of the AGN and is accelerated hydrodynamically. An external hydrostatic and/or magnetohydrodynamic pressure collimates the flow. In this work a simple relativistic hydrodynamic scheme that produces a simultaneously accelerating and converging flow is coupled with a detailed calculation of the evolution of the electron energy distribution and synchrotron emissivity due to relativistic electrons radiating in a mostly random magnetic field. Higher frequency radiation emanates from smaller distances from the central engine, implying shorter flux variation timescales at higher frequencies, as observed. The velocity of the jet increases with distance; this implies larger Doppler boosting for greater distances down the jet up to the point where the Lorentz factor Gamma la theta (-1) , where theta is the angle between the velocity vector and the line of sight, and therefore at lower frequencies. This can explain some of the differences between RBLs and XBLs as a line-of-sight orientation effect. A square density wave is propagated with the jet velocity and the variability thus induced is studied, taking into account time delay effects. The model is found to agree qualitatively with the observed steady state spectra as well as with the observed variability properties of BL Lac objects.

Laser Transmitter Aims At Laser Beacon

NASA Technical Reports Server (NTRS)

Hemmati, Hamid; Lesh, James R.

1993-01-01

Transmitter part of developmental optical communication system. Compact, lightweight, partially-self-aiming laser transmitter built to verify some capabilities of developmental free-space optical communication system. Design capable of providing 0.5 Mbps data return over range equal to Moon-Earth distance. Breadboard of transmitting terminal constructed and tested in laboratory. Prototype transmitter includes receiving circuitry that keeps it aimed at beacon, once brought into initial alignment within about 1.7 degrees of line of sight to beacon.

Looking south from the earth covered roof of magazine A213, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Looking south from the earth covered roof of magazine A-213, past the north fronts of magazine A-218 and A-219 in the middle distance, to the communications tower on the high horizon. Magazine A-210 is located on the right side of the road, out of sight to the right. Building A-167 at left. - Mare Island Naval Shipyard, Magazine, Corbett Road, southwest end of Kieper Road, Vallejo, Solano County, CA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, M. L.; McLaughlin, M. A.; Lam, M. T.

We analyze dispersion measure (DM) variations of 37 millisecond pulsars in the nine-year North American Nanohertz Observatory for Gravitational Waves (NANOGrav) data release and constrain the sources of these variations. DM variations can result from a changing distance between Earth and the pulsar, inhomogeneities in the interstellar medium, and solar effects. Variations are significant for nearly all pulsars, with characteristic timescales comparable to or even shorter than the average spacing between observations. Five pulsars have periodic annual variations, 14 pulsars have monotonically increasing or decreasing trends, and 14 pulsars show both effects. Of the four pulsars with linear trends thatmore » have line-of-sight velocity measurements, three are consistent with a changing distance and require an overdensity of free electrons local to the pulsar. Several pulsars show correlations between DM excesses and lines of sight that pass close to the Sun. Mapping of the DM variations as a function of the pulsar trajectory can identify localized interstellar medium features and, in one case, an upper limit to the size of the dispersing region of 4 au. Four pulsars show roughly Kolmogorov structure functions (SFs), and another four show SFs less steep than Kolmogorov. One pulsar has too large an uncertainty to allow comparisons. We discuss explanations for apparent departures from a Kolmogorov-like spectrum, and we show that the presence of other trends and localized features or gradients in the interstellar medium is the most likely cause.« less

Effective scattering coefficient of the cerebral spinal fluid in adult head models for diffuse optical imaging

NASA Astrophysics Data System (ADS)

Custo, Anna; Wells, William M., III; Barnett, Alex H.; Hillman, Elizabeth M. C.; Boas, David A.

2006-07-01

An efficient computation of the time-dependent forward solution for photon transport in a head model is a key capability for performing accurate inversion for functional diffuse optical imaging of the brain. The diffusion approximation to photon transport is much faster to simulate than the physically correct radiative transport equation (RTE); however, it is commonly assumed that scattering lengths must be much smaller than all system dimensions and all absorption lengths for the approximation to be accurate. Neither of these conditions is satisfied in the cerebrospinal fluid (CSF). Since line-of-sight distances in the CSF are small, of the order of a few millimeters, we explore the idea that the CSF scattering coefficient may be modeled by any value from zero up to the order of the typical inverse line-of-sight distance, or approximately 0.3 mm-1, without significantly altering the calculated detector signals or the partial path lengths relevant for functional measurements. We demonstrate this in detail by using a Monte Carlo simulation of the RTE in a three-dimensional head model based on clinical magnetic resonance imaging data, with realistic optode geometries. Our findings lead us to expect that the diffusion approximation will be valid even in the presence of the CSF, with consequences for faster solution of the inverse problem.

High-velocity interstellar gas in the line of sight to the Wolf-Rayet star HD 50896

NASA Technical Reports Server (NTRS)

Nichols-Bohlin, J.; Fesen, R. A.

1986-01-01

The large shell of interstellar gas (IG) discovered toward HD 50896 by Heckathorn and Fesen (1984) is characterized on the basis of high-dispersion IUE SWP and LWR spectra of 19 objects located within 4 deg of HD 50896 (but outside the optical ring nebula S308) at distances 0.6-2.9 kpc (compared to 1.5 kpc for HD 50896). The IG is found to have two components (at velocities -80 and -125 km/s), diameter 90 pc or greater, and distance 1.0 + or - 0.2 kpc, demonstrating that it is not related to HD 50896 and suggesting that it is a highly evolved supernova remnant associated with cluster Cr 121.

An imaging system based on laser optical feedback for fog vision applications

NASA Astrophysics Data System (ADS)

Belin, E.; Boucher, V.

2008-08-01

The Laboratoire Régional des Ponts et Chaussées d'Angers - LRPC of Angers is currently studying the feasability of applying an optical technique based on the principle of the laser optical feedback to long distance fog vision. Optical feedback set up allows the creation of images on roadsigns. To create artificial fog conditions we used a vibrating cell that produces a micro-spray of water according to the principle of acoustic cavitation. To scale the sensitivity of the system under duplicatible conditions we also used optical densities linked to first-sight visibility distances. The current system produces, in a few seconds, 200 × 200 pixel images of a roadsign seen through dense artificial fog.

OH maser proper motions in Cepheus A

NASA Astrophysics Data System (ADS)

Migenes, V.; Cohen, R. J.; Brebner, G. C.

1992-02-01

MERLIN measurements made between 1982 and 1989 reveal proper motions of OH masers in the source Cepheus A. The proper motions are typically a few milliarcsec per year, and are mainly directed away from the central H II regions. Statistical analysis of the data suggests an expansion time-scale of some 300 yr. The distance of the source implied by the proper motions is 320+140/-80 pc, assuming that the expansion is isotropic. The proper motions can be reconciled with the larger distance of 730 pc which is generally accepted, provided that the masers are moving at large angles to the line of sight. The expansion time-scale agrees with that of the magnetic field decay recently reported by Cohen, et al. (1990).

Optimal strategies in the neighborhood of a collision course

NASA Technical Reports Server (NTRS)

Gutman, S.; Leitmann, G.

1976-01-01

We consider a simple differential game between pursuer P and evader E in the neighborhood of a nominal collision course. The payoff is the terminal lateral miss-distance. The control of each player is his acceleration normal to his velocity vector, and both players' controls are bounded. Saddlepoint strategies are deduced for three combinations of the acceleration bounds and are shown to be related to the sign of the derivative of the orientation of the line of sight (L.O.S.).

Ultracold Mixtures of Rubidium and Ytterbium for Open Quantum System Engineering

DTIC Science & Technology

2014-06-01

was replaced with a standard nipple since the actual thermal conduction is comparable. Second, the collimation tube (5 mm ID x 15 cm length) was...Presumably, there is some sort of thin layer coating the Yb which must first be driven off. The helium buffer gas serves to shorten the mean free...path below the line-of-sight distance to the windows, and we can leave them at room temperature without coating them with Yb. The buffer gas causes

Estimation of distances to stars with stellar parameters from LAMOST

DOE PAGES

Carlin, Jeffrey L.; Liu, Chao; Newberg, Heidi Jo; ...

2015-06-05

Here, we present a method to estimate distances to stars with spectroscopically derived stellar parameters. The technique is a Bayesian approach with likelihood estimated via comparison of measured parameters to a grid of stellar isochrones, and returns a posterior probability density function for each star's absolute magnitude. We tailor this technique specifically to data from the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST) survey. Because LAMOST obtains roughly 3000 stellar spectra simultaneously within each ~5-degree diameter "plate" that is observed, we can use the stellar parameters of the observed stars to account for the stellar luminosity function and targetmore » selection effects. This removes biasing assumptions about the underlying populations, both due to predictions of the luminosity function from stellar evolution modeling, and from Galactic models of stellar populations along each line of sight. Using calibration data of stars with known distances and stellar parameters, we show that our method recovers distances for most stars within ~20%, but with some systematic overestimation of distances to halo giants. We apply our code to the LAMOST database, and show that the current precision of LAMOST stellar parameters permits measurements of distances with ~40% error bars. This precision should improve as the LAMOST data pipelines continue to be refined.« less

Estimation of distances to stars with stellar parameters from LAMOST

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlin, Jeffrey L.; Liu, Chao; Newberg, Heidi Jo

Here, we present a method to estimate distances to stars with spectroscopically derived stellar parameters. The technique is a Bayesian approach with likelihood estimated via comparison of measured parameters to a grid of stellar isochrones, and returns a posterior probability density function for each star's absolute magnitude. We tailor this technique specifically to data from the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST) survey. Because LAMOST obtains roughly 3000 stellar spectra simultaneously within each ~5-degree diameter "plate" that is observed, we can use the stellar parameters of the observed stars to account for the stellar luminosity function and targetmore » selection effects. This removes biasing assumptions about the underlying populations, both due to predictions of the luminosity function from stellar evolution modeling, and from Galactic models of stellar populations along each line of sight. Using calibration data of stars with known distances and stellar parameters, we show that our method recovers distances for most stars within ~20%, but with some systematic overestimation of distances to halo giants. We apply our code to the LAMOST database, and show that the current precision of LAMOST stellar parameters permits measurements of distances with ~40% error bars. This precision should improve as the LAMOST data pipelines continue to be refined.« less

K-shell Photoabsorption of Oxygen Ions

NASA Technical Reports Server (NTRS)

Garcia, J.; Mendoza, C.; Bautista, M. A.; Gorczyca, T. W.; Kallman, T. R.; Palmeri, P.

2005-01-01

The high spectral resolutions of the Chandra and XMM-Newton X-ray observatories have unveiled the useful diagnostic possibilities of oxygen K absorption. To mention a few, strong O VII and O VIII edges are almost ubiquitous in the spectra of Seyfert 1 galaxies which have been used by Lee et al. (2001) to predict of a warm dust absorber along the line of sight; although this conclusion has been criticized in the light of a data reanalysis (SA0 et al. 2003), Steenbrugge et al. (2003) have detected inner-shell transitions of O III-O VI in the spectrum of NGC 5548 that point to a warm absorber that spans three orders of magnitude in ionization parameter. Moreover, Behar et al. (2003) have stressed that, in the case of both Seyfert 1 and Seyfert 2 galaxies, a broad range of oxygen charge states are usually observed along the line of sight that must be fitted simultaneously, and may imply strong density gradients of 2-4 orders of magnitude over short distances.

Spacecraft intercept guidance using zero effort miss steering

NASA Astrophysics Data System (ADS)

Newman, Brett

The suitability of proportional navigation, or an equivalent zero effort miss formulation, for spacecraft intercepts during midcourse guidance, followed by a ballistic coast to the endgame, is addressed. The problem is formulated in terms of relative motion in a general 3D framework. The proposed guidance law for the commanded thrust vector orientation consists of the sum of two terms: (1) along the line of sight unit direction and (2) along the zero effort miss component perpendicular to the line of sight and proportional to the miss itself and a guidance gain. If the guidance law is to be suitable for longer range targeting applications with significant ballistic coasting after burnout, determination of the zero effort miss must account for the different gravitational accelerations experienced by each vehicle. The proposed miss determination techniques employ approximations for the true differential gravity effect. Theoretical results are applied to a numerical engagement scenario and the resulting performance is evaluated in terms of the miss distances determined from nonlinear simulation.

Distance still matters. The hard reality of global expansion.

PubMed

Ghemawat, P

2001-09-01

Companies routinely overestimate the attractiveness of foreign markets. Dazzled by the sheer size of untapped markets, they lose sight of the difficulties of pioneering new, often very different territories. The problem is rooted in the analytic tools (the most prominent being country portfolio analysis, or CPA) that managers use to judge international investments. By focusing on national wealth, consumer income, and people's propensity to consume, CPA emphasizes potential sales, ignoring the costs and risks of doing business in a new market. Most of these costs and risks result from the barriers created by distance. "Distance," however, does not refer only to geography; its other dimensions can make foreign markets considerably more or less attractive. The CAGE framework of distance presented here considers four attributes: cultural distance (religious beliefs, race, social norms, and language that are different for the target country and the country of the company considering expansion); administrative or political distance (colony-colonizer links, common currency, and trade arrangements); geographic distance (the physical distance between the two countries, the size of the target country, access to waterways and the ocean, internal topography, and transportation and communications infrastructures); and economic distance (disparities in the two countries' wealth or consumer income and variations in the cost and quality of financial and other resources). This framework can help to identify the ways in which potential markets may be distant from existing ones. The article explores how (and by how much) various types of distance can affect different types of industries and shows how dramatically an explicit consideration of distance can change a company's picture of its strategic options.

Interstellar Deuterium, Nitrogen and Oxygen Towards HZ43A: Results from the Far Ultraviolet Spectroscopic Explorer (FUSE) Mission

NASA Technical Reports Server (NTRS)

Kruk, J. W.; Howk, J. C.; Andre, M.; Moos, H. W.; Oegerle, William R.; Oliveira, C.; Sembach, K. R.; Chayer, P.; Linsky, J. L.; Wood, B. E.

2002-01-01

We present an analysis of interstellar absorption along the line of sight to the nearby white dwarf star HZ43A. The distance to this star is 68+/-13 pc, and the line of sight extends toward the north Galactic pole. Column densities of O(I), N(I), and N(II) were derived from spectra obtained by the Far Ultraviolet Spectroscopic Explorer (FUSE), the column density of D(I) was derived from a combination of our FUSE spectra and an archival HST GARDENS spectrum, and the column density of H(I) was derived from a combination of the GARDENS spectrum and values derived from EUVE data obtained from the literature. We find the following abundance ratios (with 2 sigma uncertainties): D(I)/H(I)=(1.66+/-0.28)x10(exp -5), O(I)/H(I)=(3.63+/-0.84)x10(exp -4), and N(I)/H(I)=(3.80+/-0.74)x10(exp -5). The N(II) column density was slightly greater than that of N(I), indicating that ionization corrections are important when deriving nitrogen abundances. Other interstellar species detected along the line of sight were C(II), C(III), O(VI), Si(II), Ar(I), Mg(II) and Fe(II); an upper limit was determined for N(III). No elements other than H(I) were detected in the stellar photosphere.

Exploring the Structure of the Distant Universe with MUSE Data Cubes

NASA Astrophysics Data System (ADS)

MacDougall, Mason; Christensen, Lise

2018-01-01

The mass distribution in intergalactic and circumgalactic space is not well known since it is difficult to characterize objects in the distant universe. An ideal tool for studying such distant structure is the Multi-Unit Spectroscopic Explorer (MUSE) of the Very Large Telescope array, which employs a wide field-of-view and a large spectral range to produce high spatial resolution datasets. Here we exploit the 2 spatial dimensions and 1 spectral dimension of a particular MUSE “data cube” to identify and characterize emission line sources near the line-of-sight to quasar PKS1937-101, which lies at a redshift of z=3.787. In particular, we search for galaxy companions to a z=3.572 Lyman-limit system measured in the quasar spectrum and find an associated Lyman-alpha emitter at z=3.556 with a projected distance of 30.2 kpc from the quasar line-of-sight. Through a combination of automated source extraction and manual investigation, we also identify 25 emission line galaxies and 1 other Lyman-alpha emitter in our field. The proximity of several of these objects to the quasar line-of-sight allows us to reliably identify absorption lines in the quasar spectrum that can be associated with observed emission lines with resolved fluxes. This will help characterize the metallicities and kinematics of galaxy halos and circumgalactic media in the early universe.

Indoor Spatial Updating With Impaired Vision

PubMed Central

Legge, Gordon E.; Granquist, Christina; Baek, Yihwa; Gage, Rachel

2016-01-01

Purpose Spatial updating is the ability to keep track of position and orientation while moving through an environment. We asked how normally sighted and visually impaired subjects compare in spatial updating and in estimating room dimensions. Methods Groups of 32 normally sighted, 16 low-vision, and 16 blind subjects estimated the dimensions of six rectangular rooms. Updating was assessed by guiding the subjects along three-segment paths in the rooms. At the end of each path, they estimated the distance and direction to the starting location, and to a designated target. Spatial updating was tested in five conditions ranging from free viewing to full auditory and visual deprivation. Results The normally sighted and low-vision groups did not differ in their accuracy for judging room dimensions. Correlations between estimated size and physical size were high. Accuracy of low-vision performance was not correlated with acuity, contrast sensitivity, or field status. Accuracy was lower for the blind subjects. The three groups were very similar in spatial-updating performance, and exhibited only weak dependence on the nature of the viewing conditions. Conclusions People with a wide range of low-vision conditions are able to judge room dimensions as accurately as people with normal vision. Blind subjects have difficulty in judging the dimensions of quiet rooms, but some information is available from echolocation. Vision status has little impact on performance in simple spatial updating; proprioceptive and vestibular cues are sufficient. PMID:27978556

Shape of magnifiers affects controllability in children with visual impairment.

PubMed

Liebrand-Schurink, Joyce; Boonstra, F Nienke; van Rens, Ger H M B; Cillessen, Antonius H N; Meulenbroek, Ruud G J; Cox, Ralf F A

2016-12-01

This study aimed to examine the controllability of cylinder-shaped and dome-shaped magnifiers in young children with visual impairment. This study investigates goal-directed arm movements in low-vision aid use (stand and dome magnifier-like object) in a group of young children with visual impairment (n = 56) compared to a group of children with normal sight (n = 66). Children with visual impairment and children with normal sight aged 4-8 years executed two types of movements (cyclic and discrete) in two orientations (vertical or horizontal) over two distances (10 cm and 20 cm) with two objects resembling the size and shape of regularly prescribed stand and dome magnifiers. The visually impaired children performed slower movements than the normally sighted children. In both groups, the accuracy and speed of the reciprocal aiming movements improved significantly with age. Surprisingly, in both groups, the performance with the dome-shaped object was significantly faster (in the 10 cm condition and 20 cm condition with discrete movements) and more accurate (in the 20 cm condition) than with the stand-shaped object. From a controllability perspective, this study suggests that it is better to prescribe dome-shaped than cylinder-shaped magnifiers to young children with visual impairment. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Indoor Spatial Updating With Impaired Vision.

PubMed

Legge, Gordon E; Granquist, Christina; Baek, Yihwa; Gage, Rachel

2016-12-01

Spatial updating is the ability to keep track of position and orientation while moving through an environment. We asked how normally sighted and visually impaired subjects compare in spatial updating and in estimating room dimensions. Groups of 32 normally sighted, 16 low-vision, and 16 blind subjects estimated the dimensions of six rectangular rooms. Updating was assessed by guiding the subjects along three-segment paths in the rooms. At the end of each path, they estimated the distance and direction to the starting location, and to a designated target. Spatial updating was tested in five conditions ranging from free viewing to full auditory and visual deprivation. The normally sighted and low-vision groups did not differ in their accuracy for judging room dimensions. Correlations between estimated size and physical size were high. Accuracy of low-vision performance was not correlated with acuity, contrast sensitivity, or field status. Accuracy was lower for the blind subjects. The three groups were very similar in spatial-updating performance, and exhibited only weak dependence on the nature of the viewing conditions. People with a wide range of low-vision conditions are able to judge room dimensions as accurately as people with normal vision. Blind subjects have difficulty in judging the dimensions of quiet rooms, but some information is available from echolocation. Vision status has little impact on performance in simple spatial updating; proprioceptive and vestibular cues are sufficient.

A speckle hologram of the interstellar plasma

NASA Technical Reports Server (NTRS)

Desai, K. M.; Gwinn, C. R.; Reynolds, J.; King, E. A.; Jauncey, D.; Flanagan, C.; Nicolson, G.; Preston, R. A.; Jones, D. L.

1992-01-01

Observations of a speckle hologram of scattering material along the line of sight to the Vela pulsar indicate that this material is concentrated in the Vela supernova remnant, deep within the Gum Nebula. The speckle hologram is observed through the amplitude and phase variations of the interferometric cross-power spectrum with time and frequency. These variations describe the density fluctuations of the interstellar plasma, in a holographic fashion. The decorrelation due to the phase variations of the speckles yields the angular size of the scattering disk; comparison with the bandwidth of their amplitude variations yields a characteristic distance from earth to the scattering material of 0.81 +/- 0.03 of the distance from earth to the pulsar. This result is consistent with theories of irregularities associated with particle acceleration in shocks in supernova remnants.

Through thick and thin: Structure of the Galactic thick disc from extragalactic surveys

NASA Astrophysics Data System (ADS)

Kordopatis, G.; Hill, V.; Irwin, M.; Gilmore, G.; Wyse, R. F. G.; Tolstoy, E.; de Laverny, P.; Recio-Blanco, A.; Battaglia, G.; Starkenburg, E.

2013-07-01

Context. We aim to understand the accretion history of the Milky Way by exploring the vertical and radial properties of the Galactic thick disc. Aims: We study the chemical and kinematic properties of roughly a thousand spectra of faint magnitude foreground Galactic stars observed serendipitously during extra-galactic surveys in four lines-of-sight: three in the southern Galactic hemisphere (surveys of the Carina, Fornax and Sculptor dwarf spheroidal galaxies) and one in the northern Galactic hemisphere (a survey of the Sextans dwarf spheroidal galaxy). The foreground stars span distances up to ~3 kpc from the Galactic plane and Galactocentric radii up to 11 kpc. Methods: The stellar atmospheric parameters (effective temperature, surface gravity, metallicity) are obtained by an automated parameterisation pipeline and the distances of the stars are then derived by a projection of the atmospheric parameters on a set of theoretical isochrones using a Bayesian approach. The metallicity gradients are estimated for each line-of-sight and compared with predictions from the Besançon model of the Galaxy, in order to test the chemical structure of the thick disc. Finally, we use the radial velocities in each line-of-sight to derive a proxy for either the azimuthal or the vertical component of the orbital velocity of the stars. Results: Only three lines-of-sight have a sufficient number of foreground stars for a robust analysis. Towards Sextans in the Northern Galactic hemisphere and Sculptor in the South, we measure a consistent decrease in mean metallicity with height from the Galactic plane, suggesting a chemically symmetric thick disc. This decrease can either be due to an intrinsic thick disc metallicity gradient, or simply due to a change in the thin disc/thick disc population ratio and no intrinsic metallicity gradients for the thick disc. We favour the latter explanation. In contrast, we find evidence of an unpredicted metal-poor population in the direction of Carina. This population was earlier detected, but our more detailed analysis provides robust estimates of its location (|Z| < 1 kpc), metallicity (-2 < [M/H] < -1 dex) and azimuthal orbital velocity (Vφ ~ 120 km s-1). Conclusions: Given the chemo-dynamical properties of the over-density towards the Carina line-of-sight, we suggest that it represents the metal-poor tail of the canonical thick disc. In spite of the small number of stars available, we suggest that this metal-weak thick disc follows the often suggested canonical thick disc velocity-metallicity correlation of ∂Vφ/∂ [M/H] ~ 40-50 km s-1 dex-1. Based on observations collected at the European Southern Observatory at Paranal, Chile, ESO Large Programme 171.B-0588 (DART) and 171.B-0520(A).Full Tables 2 and 4 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/555/A12

Software for Use with Optoelectronic Measuring Tool

NASA Technical Reports Server (NTRS)

Ballard, Kim C.

2004-01-01

A computer program has been written to facilitate and accelerate the process of measurement by use of the apparatus described in "Optoelectronic Tool Adds Scale Marks to Photographic Images" (KSC-12201). The tool contains four laser diodes that generate parallel beams of light spaced apart at a known distance. The beams of light are used to project bright spots that serve as scale marks that become incorporated into photographic images (including film and electronic images). The sizes of objects depicted in the images can readily be measured by reference to the scale marks. The computer program is applicable to a scene that contains the laser spots and that has been imaged in a square pixel format that can be imported into a graphical user interface (GUI) generated by the program. It is assumed that the laser spots and the distance(s) to be measured all lie in the same plane and that the plane is perpendicular to the line of sight of the camera used to record the image

GAIA: A WINDOW TO LARGE-SCALE MOTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nusser, Adi; Branchini, Enzo; Davis, Marc, E-mail: adi@physics.technion.ac.il, E-mail: branchin@fis.uniroma3.it, E-mail: mdavis@berkeley.edu

2012-08-10

Using redshifts as a proxy for galaxy distances, estimates of the two-dimensional (2D) transverse peculiar velocities of distant galaxies could be obtained from future measurements of proper motions. We provide the mathematical framework for analyzing 2D transverse motions and show that they offer several advantages over traditional probes of large-scale motions. They are completely independent of any intrinsic relations between galaxy properties; hence, they are essentially free of selection biases. They are free from homogeneous and inhomogeneous Malmquist biases that typically plague distance indicator catalogs. They provide additional information to traditional probes that yield line-of-sight peculiar velocities only. Further, becausemore » of their 2D nature, fundamental questions regarding vorticity of large-scale flows can be addressed. Gaia, for example, is expected to provide proper motions of at least bright galaxies with high central surface brightness, making proper motions a likely contender for traditional probes based on current and future distance indicator measurements.« less

A line transect model for aerial surveys

USGS Publications Warehouse

Quang, Pham Xuan; Lanctot, Richard B.

1991-01-01

We employ a line transect method to estimate the density of the common and Pacific loon in the Yukon Flats National Wildlife Refuge from aerial survey data. Line transect methods have the advantage of automatically taking into account “visibility bias” due to detectability difference of animals at different distances from the transect line. However, line transect methods must overcome two difficulties when applied to inaccurate recording of sighting distances due to high travel speeds, so that in fact only a few reliable distance class counts are available. We propose a unimodal detection function that provides an estimate of the effective area lost due to the blind strip, under the assumption that a line of perfect detection exists parallel to the transect line. The unimodal detection function can also be applied when a blind strip is absent, and in certain instances when the maximum probability of detection is less than 100%. A simple bootstrap procedure to estimate standard error is illustrated. Finally, we present results from a small set of Monte Carlo experiments.

Preferred viewing distance and screen angle of electronic paper displays.

PubMed

Shieh, Kong-King; Lee, Der-Song

2007-09-01

This study explored the viewing distance and screen angle for electronic paper (E-Paper) displays under various light sources, ambient illuminations, and character sizes. Data analysis showed that the mean viewing distance and screen angle were 495 mm and 123.7 degrees. The mean viewing distances for Kolin Chlorestic Liquid Crystal display was 500 mm, significantly longer than Sony electronic ink display, 491 mm. Screen angle for Kolin was 127.4 degrees, significantly greater than that of Sony, 120.0 degrees. Various light sources revealed no significant effect on viewing distances; nevertheless, they showed significant effect on screen angles. The screen angle for sunlight lamp (D65) was similar to that of fluorescent lamp (TL84), but greater than that of tungsten lamp (F). Ambient illumination and E-paper type had significant effects on viewing distance and screen angle. The higher the ambient illumination was, the longer the viewing distance and the lesser the screen angle. Character size had significant effect on viewing distances: the larger the character size, the longer the viewing distance. The results of this study indicated that the viewing distance for E-Paper was similar to that of visual display terminal (VDT) at around 500 mm, but greater than normal paper at about 360 mm. The mean screen angle was around 123.7 degrees, which in terms of viewing angle is 29.5 degrees below horizontal eye level. This result is similar to the general suggested viewing angle between 20 degrees and 50 degrees below the horizontal line of sight.

The Nanograv Nine-Year Data Set: Measurement and Analysis of Variations in Dispersion Measures

NASA Technical Reports Server (NTRS)

Jones, M. L.; McLaughlin, M. A.; Lam, M. T.; Cordes, J. M.; Levin, L.; Chatterjee, S.; Arzoumanian, Z.; Crowter, K.; Demorest, P. B.; Dolch, T.;

The molecular chemistry of diffuse and translucent clouds in the line-of-sight to Sgr B2: Absorption by simple organic and inorganic molecules in the GBT PRIMOS survey

NASA Astrophysics Data System (ADS)

Corby, J. F.; McGuire, B. A.; Herbst, E.; Remijan, A. J.

2018-02-01

The 1-50 GHz PRebiotic Interstellar MOlecular Survey (PRIMOS) contains 50 molecular absorption lines observed in clouds located in the line-of-sight to Sgr B2(N). The line-of-sight material is associated with diffuse and translucent clouds located in the Galactic center, bar, and spiral arms in the disk. We measured the column densities and estimate abundances, relative to H2, of 11 molecules and additional isotopologues observed in this material. We used absorption by optically thin transitions of c-C3H2 to estimate the molecular hydrogen columns, and argue that this method is preferable to more commonly used methods. We discuss the kinematic structure and abundance patterns of small molecules including the sulfur-bearing species CS, SO, CCS, H2CS, and HCS+; oxygen-bearing molecules OH, SiO, and H2CO; and simple hydrocarbon molecules c-C3H2, l-C3H, and l-C3H+. Finally, we discuss the implications of the observed chemistry for the structure of the gas and dust in the ISM. Highlighted results include the following. First, whereas gas in the disk has a molecular hydrogen fraction of 0.65, clouds on the outer edge of the Galactic bar and in or near the Galactic center have molecular fractions of 0.85 and >0.9, respectively. Second, we observe trends in isotope ratios with Galactocentric distance; while carbon and silicon show enhancement of the rare isotopes at low Galactocentric distances, sulfur exhibits no trend with Galactocentric distance. We also determine that the ratio of c-C3H2/c-H13CCCH provides a good estimate of the 12C/13C ratio, whereas H2CO/H213CO exhibits fractionation. Third, we report the presence of l-C3H+ in diffuse clouds for the first time. Finally, we suggest that CS has an enhanced abundance within higher density clumps of material in the disk, and therefore may be diagnostic of cloud conditions. If this holds, the diffuse clouds in the Galactic disk contain multiple embedded hyperdensities in a clumpy structure, and the density profile is not a simple function of AV. The reduced spectra (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/610/A10

Fading characteristics of maritime propagation channel for beyond geometrical horizon communications in C-band

NASA Astrophysics Data System (ADS)

Wang, Wei; Raulefs, Ronald; Jost, Thomas

2017-12-01

The design of a maritime communication system requires the understanding of the wireless propagation channel above the sea. For broadband communication systems, a carrier frequency in the C-band is of interest because of allocatable spectrum. Therefore, the German Aerospace Center performed a long-distance channel measurement campaign at 5.2 GHz on the North sea to investigate large and small-scale fading characteristics. The results show that our measurement data conforms with the ITU-R and the Bullington's path loss model to predict the power loss caused by diffraction over the Earth's surface. Further, the first tap of the channel impulse response experiences Rician fading due to superposition of a strong line-of-sight (LoS) path and multipath components originating from the sea surface and ship body. We found that the fading of the second tap follows a Rician distribution, but with a much smaller K-factor compared to the first tap. The K-factor showed a dependence on the distance between the transmitter and receiver. Particularly, the K-factor of the first tap decreases significantly when the distance between the transmitter and receiver is larger than the clearance distance of the first Fresnel zone. Therefore, we propose a distance-dependent K-factor model for the first and the second tap.

Limitations to mapping habitat-use areas in changing landscapes using the Mahalanobis distance statistic

USGS Publications Warehouse

Knick, Steven T.; Rotenberry, J.T.

1998-01-01

We tested the potential of a GIS mapping technique, using a resource selection model developed for black-tailed jackrabbits (Lepus californicus) and based on the Mahalanobis distance statistic, to track changes in shrubsteppe habitats in southwestern Idaho. If successful, the technique could be used to predict animal use areas, or those undergoing change, in different regions from the same selection function and variables without additional sampling. We determined the multivariate mean vector of 7 GIS variables that described habitats used by jackrabbits. We then ranked the similarity of all cells in the GIS coverage from their Mahalanobis distance to the mean habitat vector. The resulting map accurately depicted areas where we sighted jackrabbits on verification surveys. We then simulated an increase in shrublands (which are important habitats). Contrary to expectation, the new configurations were classified as lower similarity relative to the original mean habitat vector. Because the selection function is based on a unimodal mean, any deviation, even if biologically positive, creates larger Malanobis distances and lower similarity values. We recommend the Mahalanobis distance technique for mapping animal use areas when animals are distributed optimally, the landscape is well-sampled to determine the mean habitat vector, and distributions of the habitat variables does not change.

Optimal Guidance of a Relay MAV for ISR Support Beyond Line-of-Sight

DTIC Science & Technology

2008-03-01

Pythagoras Theorem : 1 2 22 2 2 2 2 2 2 sin 4 4 cos c E c E O E E O E O EE r BE r rr r r r r θ θ = − ⎡ ⎤ = −⎢ ⎥+ −⎣ ⎦ 1 22 2 2 2 4 4 cos cos 4 4 cos...points such that the sum of the distances from two fixed points is constant, is an ellipse. Thus, the following is of some interest. Theorem 1 The Locus

Correction And Use Of Jitter In Television Images

NASA Technical Reports Server (NTRS)

Diner, Daniel B.; Fender, Derek H.; Fender, Antony R. H.

1989-01-01

Proposed system stabilizes jittering television image and/or measures jitter to extract information on motions of objects in image. Alternative version, system controls lateral motion on camera to generate stereoscopic views to measure distances to objects. In another version, motion of camera controlled to keep object in view. Heart of system is digital image-data processor called "jitter-miser", which includes frame buffer and logic circuits to correct for jitter in image. Signals from motion sensors on camera sent to logic circuits and processed into corrections for motion along and across line of sight.

KSC-07pd3143

NASA Image and Video Library

2007-11-06

KENNEDY SPACE CENTER, FLA. -- A dolphin surfaces in the Launch Complex 39 Area turn basin at NASA's Kennedy Space Center. The turn basin was carved out of the Banana River when Kennedy Space Center was built. Dolphins frequent bays and coastlines, usually in depths under 20 meters. While some pods take up permanent residence and establish home waters, others are migratory and swim considerable distances from coast to coast. Dolphins are a frequent sight in the rivers around Kennedy, which shares a boundary with the Merritt Island Wildlife Nature Refuge. Photo credit: NASA/George Shelton

Test Area C-72 and Line of Sight, Eglin Air Force Base, Florida Final Range Environmental Assessment (REA), Revision 1

DTIC Science & Technology

2011-07-28

missions. It was recognized that a failure to remove the trees could result in valuable data loss on Eglin test missions. Four different methods have...4-57 to 4-59) The munitions used on TA C-72 would cause noise levels ofless than 115 P- weighted (impulse sound) decibels, and receptors would not...approximate calculation is: 600 x the cube root of the net explosive weight (NEW) = distance to the reservation boundary (infeet) . No detonation can

A blind human expert echolocator shows size constancy for objects perceived by echoes.

PubMed

Milne, Jennifer L; Anello, Mimma; Goodale, Melvyn A; Thaler, Lore

2015-01-01

Some blind humans make clicking noises with their mouth and use the reflected echoes to perceive objects and surfaces. This technique can operate as a crude substitute for vision, allowing human echolocators to perceive silent, distal objects. Here, we tested if echolocation would, like vision, show size constancy. To investigate this, we asked a blind expert echolocator (EE) to echolocate objects of different physical sizes presented at different distances. The EE consistently identified the true physical size of the objects independent of distance. In contrast, blind and blindfolded sighted controls did not show size constancy, even when encouraged to use mouth clicks, claps, or other signals. These findings suggest that size constancy is not a purely visual phenomenon, but that it can operate via an auditory-based substitute for vision, such as human echolocation.

Psychophysics of human echolocation.

PubMed

Schörnich, Sven; Wallmeier, Ludwig; Gessele, Nikodemus; Nagy, Andreas; Schranner, Michael; Kish, Daniel; Wiegrebe, Lutz

2013-01-01

The skills of some blind humans orienting in their environment through the auditory analysis of reflections from self-generated sounds have received only little scientific attention to date. Here we present data from a series of formal psychophysical experiments with sighted subjects trained to evaluate features of a virtual echo-acoustic space, allowing for rigid and fine-grain control of the stimulus parameters. The data show how subjects shape both their vocalisations and auditory analysis of the echoes to serve specific echo-acoustic tasks. First, we show that humans can echo-acoustically discriminate target distances with a resolution of less than 1 m for reference distances above 3.4 m. For a reference distance of 1.7 m, corresponding to an echo delay of only 10 ms, distance JNDs were typically around 0.5 m. Second, we explore the interplay between the precedence effect and echolocation. We show that the strong perceptual asymmetry between lead and lag is weakened during echolocation. Finally, we show that through the auditory analysis of self-generated sounds, subjects discriminate room-size changes as small as 10%.In summary, the current data confirm the practical efficacy of human echolocation, and they provide a rigid psychophysical basis for addressing its neural foundations.

Probing the galactic disk and halo. 2: Hot interstellar gas toward the inner galaxy star HD 156359

NASA Technical Reports Server (NTRS)

Sembach, Kenneth R.; Savage, Blair D.; Lu, Limin

1995-01-01

We present Goddard High Resolution Spectrograph intermediate-resolution measurements of the 1233-1256 A spectral region of HD 156396, a halo star at l = 328.7 deg, b = -14.5 deg in the inner Galaxy with a line-of sight distance of 11.1 kpc and a z-distance of -2.8 kpc. The data have a resolution of 18 km/s Full Width at Half Maximum (FWHM) and a signal-to-noise ratio of approximately 50:1. We detect interstellar lines of Mg II, S II, S II, Ge II, and N V and determine log N/(Mg II) = 15.78 +0.25, -0.27, log N(Si II) greater than 13.70, log N(S II) greater than 15.76, log N(Ge II) = 12.20 +0.09,-0.11, and log N(N v) = 14.06 +/- 0.02. Assuming solar reference abundances, the diffuse clouds containing Mg, S, and Ge along the sight line have average logarithmic depletions D(Mg) = -0.6 +/- 0.3 dex, D(S) greater than -0.2 dex, and D(Ge) = -0.2 +/- 0.2 dex. The Mg and Ge depletions are approximately 2 times smaller than is typical of diffuse clouds in the solar vicinity. Galactic rotational modeling of the N v profiles indicates that the highly ionized gas traced by this ion has a scale height of approximately 1 kpc if gas at large z-distances corotates with the underlying disk gas. Rotational modeling of the Si iv and C iv profiles measured by the IUE satellite yields similar scale height estimates. The scale height results contrast with previous studies of highly ionized gas in the outer Milky Way that reveal a more extended gas distribtion with h approximately equals 3-4 kpc. We detect a high-velocity feature in N v and Si II v(sub LSR) approximately equals + 125 km/s) that is probably created in an interface between warm and hot gas.

TRACING THE HERCULES STREAM AROUND THE GALAXY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bovy, Jo, E-mail: jb2777@nyu.ed

2010-12-20

It has been proposed that the Hercules stream, a group of co-moving stars in the solar neighborhood offset from the bulk of the velocity distribution, is the result of resonant interactions between stars in the outer disk and the Galactic bar. So far it has only been seen in the immediate solar neighborhood, but the resonance model makes a prediction over a large fraction of the Galactic disk. I predict the distribution of stellar velocities and the changing Hercules feature in this distribution as a function of location in the Galactic disk in a simple model for the Galaxy andmore » the bar that produces the observed Hercules stream. The Hercules feature is expected to be strong enough to be unambiguously detected in the distribution of line-of-sight velocities in selected directions. I identify quantitatively the most promising lines of sight for detection in line-of-sight velocities using the Kullback-Leibler divergence between the predictions of the resonance model and an axisymmetric model; these directions are at 250{sup 0} {approx}< l {approx}< 290{sup 0}. The predictions presented here are only weakly affected by distance uncertainties, assumptions about the distribution function in the stellar disk, and the details of the Galactic potential including the effect of spiral structure. Gaia and future spectroscopic surveys of the Galactic disk such as APOGEE and HERMES will be able to robustly test the origin of the Hercules stream and constrain the properties of the Galactic bar.« less

ELEVEN NEW HEAVILY REDDENED FIELD WOLF-RAYET STARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, J. D. T.; Cushing, Michael; Barletta, Anthony

We report the results of a medium-narrowband 2 {mu}m line survey covering 5.8 deg{sup 2} near the Galactic plane. We confirm 11 new field Wolf-Rayet stars along three lines of sight probing the inner Galaxy, demonstrating the capability to uncover distant and highly reddened populations of Galactic wind-borne emission-line stars suffering extinction as high as A{sub V} {approx} 40 and as distant as 9 kpc down to modest magnitude limits of K{sub s} {approx} 12.5. All stars are of subtype WC7-8, with median distance d = 6 kpc and median extinction A{sub K{sub s}} = 2.5. Over the fields surveyed,more » the density of Wolf-Rayet stars to limiting magnitude K{sub s} {approx} 12.5 was found to be 1.9 deg{sup -2}. We compare this to models which predict their distribution within the Galaxy and find that, even neglecting survey and subtype incompleteness, they consistently underpredict the number of newly discovered stars along the surveyed lines of sight.« less

A New Methodology for 3D Target Detection in Automotive Radar Applications

PubMed Central

Baselice, Fabio; Ferraioli, Giampaolo; Lukin, Sergyi; Matuozzo, Gianfranco; Pascazio, Vito; Schirinzi, Gilda

2016-01-01

Today there is a growing interest in automotive sensor monitoring systems. One of the main challenges is to make them an effective and valuable aid in dangerous situations, improving transportation safety. The main limitation of visual aid systems is that they do not produce accurate results in critical visibility conditions, such as in presence of rain, fog or smoke. Radar systems can greatly help in overcoming such limitations. In particular, imaging radar is gaining interest in the framework of Driver Assistance Systems (DAS). In this manuscript, a new methodology able to reconstruct the 3D imaged scene and to detect the presence of multiple targets within each line of sight is proposed. The technique is based on the use of Compressive Sensing (CS) theory and produces the estimation of multiple targets for each line of sight, their range distance and their reflectivities. Moreover, a fast approach for 2D focus based on the FFT algorithm is proposed. After the description of the proposed methodology, different simulated case studies are reported in order to evaluate the performances of the proposed approach. PMID:27136558

Line-of-sight magnetic flux imbalances caused by electric currents

NASA Technical Reports Server (NTRS)

Gary, G. Allen; Rabin, Douglas

1995-01-01

Several physical and observational effects contribute to the significant imbalances of magnetic flux that are often observed in active regions. We consider an effect not previously treated: the influence of electric currents in the photosphere. Electric currents can cause a line-of-sight flux imbalance because of the directionality of the magnetic field they produce. Currents associated with magnetic flux tubes produce larger imbalances than do smoothly-varying distributions of flux and current. We estimate the magnitude of this effect for current densities, total currents, and magnetic geometry consistent with observations. The expected imbalances lie approximately in the range 0-15%, depending on the character of the current-carying fields and the angle from which they are viewed. Observationally, current-induced flux imbalances could be indicated by a statistical dependence of the imbalance on angular distance from disk center. A general study of magnetic flux balance in active regions is needed to determine the relative importance of other- probably larger- effects such as dilute flux (too weak to measure or rendered invisible by radiative transfer effects), merging with weak background fields, and long-range connections between active regions.

Flash/crazing effects on simulator pursuit tracking performance

NASA Astrophysics Data System (ADS)

Stamper, D. A.; Lund, D. J.; Levine, R. R.; Molchany, J. W.; Best, P.

1986-03-01

Day sights which are purposefully or inadvertently irradiated with laser radiation may become nonfunctional due to cracking or crazing of the optical glass. The degree of performance degradation may be related to the amount of damage to the glass and possible flash blindness from reradiation. Thirty-two male enlisted men and officers tracked a scale model tank through a constant arc at a simulated distance of 1 km, using a laboratory constructed viscous-damped tracking device. There were four crazing groups (4 men/group) under bright and dim ambient light conditions for a total of eight groups. Each man tracked the target during three flash/crazing and three crazing only trials, which were randomly presented during 30 trials. The simulated countermeasure which included the flash and crazing had dramatic effects on tracking performance, even under daylight conditions. Under the most severe degree of crazing, tracking performance was not possible under either ambient light condition. The relatively small amounts of laser radiation used to craze the BK-7 glass used in this study, which lead to significant performance decrements, demonstrates the potential impact of flash/crazing effects on operators of day sights.

RadioAstron Studies of the Nearby, Turbulent Interstellar Plasma with the Longest Space-Ground Interferometer Baseline

NASA Astrophysics Data System (ADS)

Smirnova, T. V.; Shishov, V. I.; Popov, M. V.; Gwinn, C. R.; Anderson, J. M.; Andrianov, A. S.; Bartel, N.; Deller, A.; Johnson, M. D.; Joshi, B. C.; Kardashev, N. S.; Karuppusamy, R.; Kovalev, Y. Y.; Kramer, M.; Soglasnov, V. A.; Zensus, J. A.; Zhuravlev, V. I.

2014-05-01

RadioAstron space-ground very long baseline interferometry observations of the pulsar B0950+08, conducted with the 10 m Space Radio Telescope in conjunction with the Arecibo 300 m telescope and the Westerbork Synthesis Radio Telescope at a frequency of 324 MHz were analyzed in order to investigate plasma inhomogeneities in the direction of this nearby pulsar. The observations were conducted at a spacecraft distance of 330,000 km, resulting in a projected baseline of 220,000 km, providing the greatest angular resolution ever achieved at meter wavelengths. Our analysis is based on fundamental behavior of structure and coherence functions. We find that the pulsar shows scintillation on two frequency scales, both much less than the observing frequency, but modulation is less than 100%. We infer that the scattering is weak, but a refracting wedge disperses the scintillation pattern. The refraction angle of this "cosmic prism" is measured as θ0 = 1.1-4.4 mas, with the refraction direction being approximately perpendicular to the observer velocity. We show that the observed parameters of scintillation effects indicate that two plasma layers lie along the line of sight to the pulsar, at distances of 4.4-16.4 pc and 26-170 pc, and traveling in different directions relative to the line of sight. Spectra of turbulence for the two layers are found to follow a power law with the indices γ1 = γ2 = 3.00 ± 0.08, significantly different from the index expected for a Kolmogorov spectrum of turbulence, γ = 11/3.

Evaluating impacts of different longitudinal driver assistance systems on reducing multi-vehicle rear-end crashes during small-scale inclement weather.

PubMed

Li, Ye; Xing, Lu; Wang, Wei; Wang, Hao; Dong, Changyin; Liu, Shanwen

2017-10-01

Multi-vehicle rear-end (MVRE) crashes during small-scale inclement (SSI) weather cause high fatality rates on freeways, which cannot be solved by traditional speed limit strategies. This study aimed to reduce MVRE crash risks during SSI weather using different longitudinal driver assistance systems (LDAS). The impact factors on MVRE crashes during SSI weather were firstly analyzed. Then, four LDAS, including Forward collision warning (FCW), Autonomous emergency braking (AEB), Adaptive cruise control (ACC) and Cooperative ACC (CACC), were modeled based on a unified platform, the Intelligent Driver Model (IDM). Simulation experiments were designed and a large number of simulations were then conducted to evaluate safety effects of different LDAS. Results indicate that the FCW and ACC system have poor performance on reducing MVRE crashes during SSI weather. The slight improvement of sight distance of FCW and the limitation of perception-reaction time of ACC lead the failure of avoiding MVRE crashes in most scenarios. The AEB system has the better effect due to automatic perception and reaction, as well as performing the full brake when encountering SSI weather. The CACC system has the best performance because wireless communication provides a larger sight distance and a shorter time delay at the sub-second level. Sensitivity analyses also indicated that the larger number of vehicles and speed changes after encountering SSI weather have negative impacts on safety performances. Results of this study provide useful information for accident prevention during SSI weather. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mapping the Asymmetric Thick Disk. II. Distance, Size, and Mass of the Hercules Thick Disk Cloud

NASA Astrophysics Data System (ADS)

Larsen, Jeffrey A.; Cabanela, Juan E.; Humphreys, Roberta M.

2011-04-01

The Hercules Thick Disk Cloud was initially discovered as an excess in the number of faint blue stars between Quadrants 1 and 4 of the Galaxy. The origin of the Cloud could be an interaction with the disk bar, a triaxial Thick Disk, or a merger remnant or stream. To better map the spatial extent of the Cloud along the line of sight, we have obtained multi-color UBVR photometry for 1.2 million stars in 63 fields each of approximately 1 deg2. Our analysis of the fields beyond the apparent boundaries of the excess has already ruled out a triaxial Thick Disk as a likely explanation. In this paper, we present our results for the star counts over all of our fields, determine the spatial extent of the overdensity across and along the line of sight, and estimate the size and mass of the Cloud. Using photometric parallaxes, the stars responsible for the excess are between 1 and 6 kpc from the Sun, 0.5-4 kpc above the Galactic plane, and extend approximately 3-4 kpc across our line of sight. The Cloud is thus a major substructure in the Galaxy. The distribution of the excess along our sight lines corresponds with the density contours of the bar in the Disk, and its most distant stars are directly over the bar. We also see through the Cloud to its far side. Over the entire 500 deg2 of the sky containing the Cloud, we estimate more than 5.6 million stars and 1.9 million solar masses of material. If the overdensity is associated with the bar, it would exceed 1.4 billion stars and more than 50 million solar masses. Finally, we argue that the Hercules-Aquila Cloud is actually the Hercules Thick Disk Cloud.

MAPPING THE ASYMMETRIC THICK DISK. II. DISTANCE, SIZE, AND MASS OF THE HERCULES THICK DISK CLOUD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Larsen, Jeffrey A.; Cabanela, Juan E.; Humphreys, Roberta M., E-mail: larsen@usna.edu, E-mail: cabanela@mnstate.edu, E-mail: roberta@umn.edu

2011-04-15

The Hercules Thick Disk Cloud was initially discovered as an excess in the number of faint blue stars between Quadrants 1 and 4 of the Galaxy. The origin of the Cloud could be an interaction with the disk bar, a triaxial Thick Disk, or a merger remnant or stream. To better map the spatial extent of the Cloud along the line of sight, we have obtained multi-color UBVR photometry for 1.2 million stars in 63 fields each of approximately 1 deg{sup 2}. Our analysis of the fields beyond the apparent boundaries of the excess has already ruled out a triaxialmore » Thick Disk as a likely explanation. In this paper, we present our results for the star counts over all of our fields, determine the spatial extent of the overdensity across and along the line of sight, and estimate the size and mass of the Cloud. Using photometric parallaxes, the stars responsible for the excess are between 1 and 6 kpc from the Sun, 0.5-4 kpc above the Galactic plane, and extend approximately 3-4 kpc across our line of sight. The Cloud is thus a major substructure in the Galaxy. The distribution of the excess along our sight lines corresponds with the density contours of the bar in the Disk, and its most distant stars are directly over the bar. We also see through the Cloud to its far side. Over the entire 500 deg{sup 2} of the sky containing the Cloud, we estimate more than 5.6 million stars and 1.9 million solar masses of material. If the overdensity is associated with the bar, it would exceed 1.4 billion stars and more than 50 million solar masses. Finally, we argue that the Hercules-Aquila Cloud is actually the Hercules Thick Disk Cloud.« less

Andromeda’s Parachute: A Bright Quadruply Lensed Quasar at z = 2.377

NASA Astrophysics Data System (ADS)

Rubin, Kate H. R.; O’Meara, John M.; Cooksey, Kathy L.; Matuszewski, Mateusz; Rizzi, Luca; Doppmann, Greg; Kwok, Shui; Martin, D. Christopher; Moore, Anna M.; Morrissey, Patrick; Neill, James D.

2018-06-01

We present Keck Cosmic Web Imager spectroscopy of the four putative images of the lensed quasar candidate J014710+463040 recently discovered by Berghea et al. The data verify the source as a quadruply lensed, broad absorption-line quasar having {z}{{S}}=2.377 +/- 0.007. We detect intervening absorption in the Fe II λλ2586, 2600, Mg II λλ2796, 2803, and/or C IV λλ1548, 1550 transitions in eight foreground systems, three of which have redshifts consistent with the photometric-redshift estimate reported for the lensing galaxy (z L ≈ 0.57). The source images probe these absorbers over transverse physical scales of ≈0.3–22 kpc, permitting assessment of the variation in metal-line equivalent width {W}{{r}} as a function of sight-line separation. We measure differences in {W}{{r},2796} of <40% across most of the sight-line pairs subtending 8–22 kpc, suggestive of a high degree of spatial coherence for the Mg II-absorbing material. {W}{{r},2600} varies by >50% over the same scales across the majority of sight-line pairs, while C IV absorption exhibits a wide range in {W}{{r},1548} differences of ≈5%–80% within transverse distances of ≲3 kpc. These spatial variations are consistent with those measured in intervening absorbers detected toward lensed quasars drawn from the literature, in which {W}{{r},2796} and {W}{{r},1548} vary by ≤20% in 35 ± 7% and 47 ± 6% of sight lines separated by <10 kpc, respectively. J014710+463040 is one of only a handful of z > 2 quadruply lensed systems for which all four source images are very bright (r = 15.4–17.7 mag) and are easily separated in ground-based seeing conditions. As such, it is an ideal candidate for higher-resolution spectroscopy probing the spatial variation in the kinematic structure and physical state of intervening absorbers.

The local spiral structure of the Milky Way

PubMed Central

Xu, Ye; Reid, Mark; Dame, Thomas; Menten, Karl; Sakai, Nobuyuki; Li, Jingjing; Brunthaler, Andreas; Moscadelli, Luca; Zhang, Bo; Zheng, Xingwu

2016-01-01

The nature of the spiral structure of the Milky Way has long been debated. Only in the last decade have astronomers been able to accurately measure distances to a substantial number of high-mass star-forming regions, the classic tracers of spiral structure in galaxies. We report distance measurements at radio wavelengths using the Very Long Baseline Array for eight regions of massive star formation near the Local spiral arm of the Milky Way. Combined with previous measurements, these observations reveal that the Local Arm is larger than previously thought, and both its pitch angle and star formation rate are comparable to those of the Galaxy’s major spiral arms, such as Sagittarius and Perseus. Toward the constellation Cygnus, sources in the Local Arm extend for a great distance along our line of sight and roughly along the solar orbit. Because of this orientation, these sources cluster both on the sky and in velocity to form the complex and long enigmatic Cygnus X region. We also identify a spur that branches between the Local and Sagittarius spiral arms. PMID:27704048

Predicted detection rates of regional-scale meteorite impacts on Mars with the InSight short-period seismometer

NASA Astrophysics Data System (ADS)

Teanby, N. A.

2015-08-01

In 2016 NASA will launch the InSight discovery-class mission, which aims to study the detailed internal structure of Mars for the first time. Short- and long-period seismometers form a major component of InSight's payload and have the potential to detect seismic waves generated by meteorite impacts. Large globally detectable impact events producing craters with diameters of ∼ 100 m have been investigated previously and are likely to be rare (Teanby, N.A., Wookey, J. [2011]. Phys. Earth Planet. Int. 186, 70-80), but smaller impacts producing craters in the 0.5-20 m range are more numerous and potentially occur sufficiently often to be detectable on regional scales (≲1000 km). At these distances, seismic waves will have significant high frequency content and will be suited to detection with InSight's short-period seismometer SEIS-SP. In this paper I estimate the current martian crater production function from observations of new craters (Malin, M.C. et al. [2006]. Science 314, 1573-1577; Daubar, I.J. et al. [2013]. Icarus 225, 506-516), model results (Williams, J.P., Pathare, A.V., Aharonson, O. [2014]. Icarus 235, 23-36), and standard isochrons (Hartmann, W.K. [2005]. Icarus 174, 294-320). These impact rates are combined with an empirical relation between impact energy, source-receiver distance, and peak seismogram amplitude, derived from a compilation of seismic recordings of terrestrial and lunar impacts, chemical explosions, and nuclear tests. The resulting peak seismogram amplitude scaling law contains significant uncertainty, but can be used to predict impact detection rates. I estimate that for a short-period instrument, with a noise spectral density of 10-8 ms-2 Hz-1/2 in the 1-16 Hz frequency band, approximately 0.1-30 regional impacts per year should be detectable with a nominal value of 1-3 impacts per year. Therefore, small regional impacts are likely to be a viable source of seismic energy for probing Mars' crustal and upper mantle structure. This is particularly appealing as such impacts should be easily located with orbital imagery, increasing their scientific value compared to other types of events with unknown origins. Finally, comparison of the empirical results presented here with the modelling study of Teanby and Wookey (Teanby, N.A., Wookey, J. [2011]. Phys. Earth Planet. Int. 186, 70-80) provides constraints on the seismic efficiency, suggesting that values of ∼ 5 × 10-4 may be appropriate for impact generated seismic waves. Comparing explosion and impact datasets indicate that buried explosions are ∼ 10 times more efficient at generating seismic waves than impacts.

Counter design influences the privacy of patients in health care.

PubMed

Mobach, Mark P

2009-03-01

A re-furnishing of counter areas in primary health care was used to assess patient privacy and its influences on the nature of conversations in a controlled experiment. Patients in two community-based pharmacies in the Netherlands were assigned to enclosed counters and a queue at distance, or to counters that exposed patients mutually and a closer queue. Patients assigned to counters with reduced sight were more satisfied with the privacy than patients at visually exposed counters. However, in comparison with visually exposed pharmacy counters, conversations of patients at enclosed counters could still be overheard and did not have different conversations to other patients. Architectural design of health-care institutions has potential to positively influence perceived patient privacy in areas in where multiple patient-staff communications routinely occur and where patient privacy is an important issue, but enclosed counters with a queue at distance do not prevent incidental disclosure of individually identifiable health information.

Retinal cell imaging in myopic chickens using adaptive optics multiphoton microscopy.

PubMed

Bueno, Juan M; Palacios, Raquel; Giakoumaki, Anastasia; Gualda, Emilio J; Schaeffel, Frank; Artal, Pablo

2014-03-01

Abnormal eye growth induced by visual deprivation can modify the structure and density of the retinal cells. We have used an adaptive optics multiphoton microscope to image photoreceptors (PRs) and ganglion cells (GCs) at different retinal locations in unstained retinas of chicken eyes with about 10D of myopia and their normal-sighted fellow eyes. In all samples, the local averaged inter-PR distance increased with eccentricity. No significant differences in PR density were found between control and myopic eyes. GC density declined in myopic eyes compared to control eyes and the inter-cell distance increased. In normal eyes, the size of the GC cell bodies increased approximately two-fold between the area centralis and the peripheral retina. In myopic eyes, this trend was preserved but the GC bodies were larger at each retinal location, compared to control eyes. Obviously, GC morphology is changing when the retinal area is enlarged in myopic eyes.

Retinal cell imaging in myopic chickens using adaptive optics multiphoton microscopy

PubMed Central

Bueno, Juan M.; Palacios, Raquel; Giakoumaki, Anastasia; Gualda, Emilio J.; Schaeffel, Frank; Artal, Pablo

2014-01-01

Abnormal eye growth induced by visual deprivation can modify the structure and density of the retinal cells. We have used an adaptive optics multiphoton microscope to image photoreceptors (PRs) and ganglion cells (GCs) at different retinal locations in unstained retinas of chicken eyes with about 10D of myopia and their normal-sighted fellow eyes. In all samples, the local averaged inter-PR distance increased with eccentricity. No significant differences in PR density were found between control and myopic eyes. GC density declined in myopic eyes compared to control eyes and the inter-cell distance increased. In normal eyes, the size of the GC cell bodies increased approximately two-fold between the area centralis and the peripheral retina. In myopic eyes, this trend was preserved but the GC bodies were larger at each retinal location, compared to control eyes. Obviously, GC morphology is changing when the retinal area is enlarged in myopic eyes. PMID:24688804

Spatial Sense and Perspective: A 3-D Model of the Orion Constellation

NASA Astrophysics Data System (ADS)

Heyer, I.; Slater, T. F.; Slater, S. J.

2012-08-01

Building a scale model of the Orion constellation provides spatial perspective for students studying astronomy. For this activity, students read a passage from literature that refers to stars being strange when seen from a different point of view. From a data set of the seven major stars of Orion they construct a 3-D distance scale model. This involves the subject areas of astronomy, mathematics, literature and art, as well as the skill areas of perspective, relative distances, line-of-sight, and basic algebra. This model will appear from one side exactly the way we see it from Earth. But when looking at it from any other angle the familiar constellation will look very alien. Students are encouraged to come up with their own names and stories to go with these new constellations. This activity has been used for K-12 teacher professional development classes, and would be most suitable for grades 6-12.

Effect of prescribed prism on monocular interpupillary distances and fitting heights for progressive add lenses.

PubMed

Brooks, C W; Riley, H D

1994-06-01

Success in fitting progressive addition lenses is dependent upon the accurate placement of the progressive zone. Both eyes must track simultaneously within the boundary of the progressive corridor. Vertical prism will displace the wearer's lines of sight and consequently eye position. Because fitting heights are measured using an empty frame, subjects with vertical phorias usually will fuse, and not show the vertical differences in pupil heights during the measuring process. Therefore, when prescriptions contain vertical prism one must consider the changes in measured fitting heights that will occur once the lenses are placed in the frame. Fitting heights must be altered approximately 0.3 mm for each vertical prism diopter prescribed. The fitting height adjustment is opposite from the base direction of the prescribed prism. An explanation of the effect of prescribed horizontal prism on monocular interpupillary distance (PD) measurements is also included.

Experience, but not distance, influences the recruitment precision in the stingless bee Scaptotrigona mexicana

NASA Astrophysics Data System (ADS)

Sánchez, Daniel; Kraus, F. Bernhard; Hernández, Manuel De Jesús; Vandame, Rémy

2007-07-01

Recruitment precision, i.e. the proportion of recruits that reach an advertised food source, is a crucial adaptation of social bees to their environment. Studies with honeybees showed that recruitment precision is not a fixed feature, but it may be enhanced by factors like experience and distance. However, little is known regarding the recruitment precision of stingless bees. Hence, in this study, we examined the effects of experience and spatial distance on the precision of the food communication system of the stingless bee Scaptotrigona mexicana. We conducted the experiments by training bees to a three-dimensional artificial patch at several distances from the colony. We recorded the choices of individual recruited foragers, either being newcomers (foragers without experience with the advertised food source) or experienced (foragers that had previously visited the feeder). We found that the average precision of newcomers (95.6 ± 2.61%) was significantly higher than that of experienced bees (80.2 ± 1.12%). While this might seem counter-intuitive on first sight, this “loss” of precision can be explained by the tendency of experienced recruits to explore nearby areas to find new rewarding food sources after they had initially learned the exact location of the food source. Increasing the distance from the colony had no significant effect on the precision of the foraging bees. Thus, our data show that experience, but not the distance of the food source, affected the patch precision of S. mexicana foragers.

New Horizons Sees Pluto (Sept. 24) Note: There is debate within the science community as to whether

NASA Technical Reports Server (NTRS)

2007-01-01

A white arrow marks Pluto in this New Horizons Long Range Reconnaissance Imager (LORRI) picture taken Sept. 21, 2006. Seen at a distance of about 4.2 billion kilometers (2.6 billion miles) from the spacecraft, Pluto is little more than a faint point of light among a dense field of stars. Mission scientists knew they had Pluto in their sights when LORRI detected an unresolved 'point' in Pluto's predicted position, moving at the planet's expected motion across the constellation of Sagittarius near the plane of the Milky Way galaxy.

New Horizons Sees Pluto (Sept. 21) Note: There is debate within the science community as to whether

NASA Technical Reports Server (NTRS)

2007-01-01

A white arrow marks Pluto in this New Horizons Long Range Reconnaissance Imager (LORRI) picture taken Sept. 21, 2006. Seen at a distance of about 4.2 billion kilometers (2.6 billion miles) from the spacecraft, Pluto is little more than a faint point of light among a dense field of stars. Mission scientists knew they had Pluto in their sights when LORRI detected an unresolved 'point' in Pluto's predicted position, moving at the planet's expected motion across the constellation of Sagittarius near the plane of the Milky Way galaxy.

Experimental research and comparison of LDPC and RS channel coding in ultraviolet communication systems.

PubMed

Wu, Menglong; Han, Dahai; Zhang, Xiang; Zhang, Feng; Zhang, Min; Yue, Guangxin

2014-03-10

We have implemented a modified Low-Density Parity-Check (LDPC) codec algorithm in ultraviolet (UV) communication system. Simulations are conducted with measured parameters to evaluate the LDPC-based UV system performance. Moreover, LDPC (960, 480) and RS (18, 10) are implemented and experimented via a non-line-of-sight (NLOS) UV test bed. The experimental results are in agreement with the simulation and suggest that based on the given power and 10(-3)bit error rate (BER), in comparison with an uncoded system, average communication distance increases 32% with RS code, while 78% with LDPC code.

KSC-07pd3144

NASA Image and Video Library

2007-11-06

KENNEDY SPACE CENTER, FLA. -- A dolphin's dorsal fin cuts through the water in the Launch Complex 39 Area turn basin at NASA's Kennedy Space Center. The turn basin was carved out of the Banana River when Kennedy Space Center was built. Dolphins frequent bays and coastlines, usually in depths under 20 meters. While some pods take up permanent residence and establish home waters, others are migratory and swim considerable distances from coast to coast. Dolphins are a frequent sight in the rivers around Kennedy, which shares a boundary with the Merritt Island Wildlife Nature Refuge. Photo credit: NASA/George Shelton

The Measurement of Auditory Abilities of Blind, Partially Sighted, and Sighted Children.

ERIC Educational Resources Information Center

Stankov, Lazar; Spilsbury, Georgina

1979-01-01

Auditory tests were administered to 30 blind, partially sighted, and sighted children. Overall, the blind and sighted were equal on most of the measured abilities. Blind children performed well on tonal memory tests. Partially sighted children performed more poorly than the other two groups. (MH)

Acoustic variation of spider monkeys' contact calls (whinnies) is related to distance between vocalizing individuals and immediate caller behavior.

PubMed

Ordóñez-Gómez, José D; Santillán-Doherty, Ana M; Fischer, Julia; Hammerschmidt, Kurt

2018-04-01

Due to several factors such as ecological conditions, group size, and social organization, primates frequently spend time out of visual contact with individuals of their own group. Through the use of long-distance vocalizations, often termed "contact calls," primates are able to maintain contact with out-of-sight individuals. Contact calls have been shown to be individually distinct, and reverberation and attenuation provide information about caller distance. It is less clear, however, whether callers actively change the structure of contact calls depending on the distance to the presumed listeners. We studied this question in spider monkeys (Ateles geoffroyi), a species with complex spatial dynamics (fission-fusion society) that produces highly frequency modulated contact calls, denominated "whinnies." We determined the acoustic characteristics of 566 whinnies recorded from 35 free-ranging spider monkeys that belong to a community located in Mexico, and used cluster analyses, discriminant function analyses, and generalized linear mixed models to assess if they varied in relation to the presumed distance to the listener. Whinnies could be grouped into five subtypes. Since the lowest frequency subtype was mainly produced by spider monkeys that exchanged whinnies at longer distances, and lower frequency calls propagate across longer distances, our results suggest that whinnies vary in order to enhance vocal contact between individuals separated by different distances. Our results also revealed that whinnies convey potential information about caller immediate behaviors and corroborated that these calls are individually distinct. Overall, our results suggest that whinny acoustic variation facilitates the maintenance of vocal contact between individuals living in a society with complex spatial dynamics. © 2018 Wiley Periodicals, Inc.

Dispersion Distance and the Matter Distribution of the Universe in Dispersion Space.

PubMed

Masui, Kiyoshi Wesley; Sigurdson, Kris

2015-09-18

We propose that "standard pings," brief broadband radio impulses, can be used to study the three-dimensional clustering of matter in the Universe even in the absence of redshift information. The dispersion of radio waves as they travel through the intervening plasma can, like redshift, be used as a cosmological distance measure. Because of inhomogeneities in the electron density along the line of sight, dispersion is an imperfect proxy for radial distance and we show that this leads to calculable dispersion-space distortions in the apparent clustering of sources. Fast radio bursts (FRBs) are a new class of radio transients that are the prototypical standard ping and, due to their high observed dispersion, have been interpreted as originating at cosmological distances. The rate of fast radio bursts has been estimated to be several thousand over the whole sky per day and, if cosmological, the sources of these events should trace the large-scale structure of the Universe. We calculate the dispersion-space power spectra for a simple model where electrons and FRBs are biased tracers of the large-scale structure of the Universe, and we show that the clustering signal could be measured using as few as 10 000 events. Such a survey is in line with what may be achieved with upcoming wide-field radio telescopes.

Dispersion Distance and the Matter Distribution of the Universe in Dispersion Space

NASA Astrophysics Data System (ADS)

Masui, Kiyoshi Wesley; Sigurdson, Kris

2015-09-01

We propose that "standard pings," brief broadband radio impulses, can be used to study the three-dimensional clustering of matter in the Universe even in the absence of redshift information. The dispersion of radio waves as they travel through the intervening plasma can, like redshift, be used as a cosmological distance measure. Because of inhomogeneities in the electron density along the line of sight, dispersion is an imperfect proxy for radial distance and we show that this leads to calculable dispersion-space distortions in the apparent clustering of sources. Fast radio bursts (FRBs) are a new class of radio transients that are the prototypical standard ping and, due to their high observed dispersion, have been interpreted as originating at cosmological distances. The rate of fast radio bursts has been estimated to be several thousand over the whole sky per day and, if cosmological, the sources of these events should trace the large-scale structure of the Universe. We calculate the dispersion-space power spectra for a simple model where electrons and FRBs are biased tracers of the large-scale structure of the Universe, and we show that the clustering signal could be measured using as few as 10 000 events. Such a survey is in line with what may be achieved with upcoming wide-field radio telescopes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCollough, M. L.; Dunham, M. M.; Corrales, L., E-mail: mmccollough@cfa.harvard.edu

Chandra observations have revealed a feature within 16″ of Cygnus X-3 that varied in phase with Cygnus X-3. This feature was shown to be a Bok globule that is along the line of sight to Cygnus X-3. We report on observations made with the Submillimeter Array to search for molecular emission from this globule, also known as Cygnus X-3's “Little Friend.” We have found a counterpart in both {sup 12}CO (2-1) and {sup 13}CO (2-1) emission. From the velocity shift of the molecular lines we are able to find two probable distances based on the Bayesian model of Milky Waymore » kinematics of Reid et al. For the LF velocity of −47.5 km s{sup −1}, we find distances of 6.1 ± 0.6 kpc (62% probability) and 7.8 ± 0.6 kpc (38% probability). This yields distances to Cyg X-3 of 7.4 ± 1.1 kpc and 10.2 ± 1.2 kpc, respectively. Based on the probabilities entailed, we take 7.4 ± 1.1 kpc as the preferred distance to Cyg X-3. We also report the discovery of bipolar molecular outflow, suggesting that there is active star formation occurring within the Little Friend.« less

How many sightings to model rare marine species distributions

PubMed Central

Authier, Matthieu; Monestiez, Pascal; Ridoux, Vincent

2018-01-01

Despite large efforts, datasets with few sightings are often available for rare species of marine megafauna that typically live at low densities. This paucity of data makes modelling the habitat of these taxa particularly challenging. We tested the predictive performance of different types of species distribution models fitted to decreasing numbers of sightings. Generalised additive models (GAMs) with three different residual distributions and the presence only model MaxEnt were tested on two megafauna case studies differing in both the number of sightings and ecological niches. From a dolphin (277 sightings) and an auk (1,455 sightings) datasets, we simulated rarity with a sighting thinning protocol by random sampling (without replacement) of a decreasing fraction of sightings. Better prediction of the distribution of a rarely sighted species occupying a narrow habitat (auk dataset) was expected compared to the distribution of a rarely sighted species occupying a broad habitat (dolphin dataset). We used the original datasets to set up a baseline model and fitted additional models on fewer sightings but keeping effort constant. Model predictive performance was assessed with mean squared error and area under the curve. Predictions provided by the models fitted to the thinned-out datasets were better than a homogeneous spatial distribution down to a threshold of approximately 30 sightings for a GAM with a Tweedie distribution and approximately 130 sightings for the other models. Thinning the sighting data for the taxon with narrower habitats seemed to be less detrimental to model predictive performance than for the broader habitat taxon. To generate reliable habitat modelling predictions for rarely sighted marine predators, our results suggest (1) using GAMs with a Tweedie distribution with presence-absence data and (2) implementing, as a conservative empirical measure, at least 50 sightings in the models. PMID:29529097

The alpha Centauri Line of Sight: D/H Ratio, Physical Properties of Local Interstellar Gas, and Measurement of Heated Hydrogen (The 'Hydrogen Wall') Near the Heliopause

NASA Astrophysics Data System (ADS)

Linsky, Jeffrey L.; Wood, Brian E.

1996-05-01

We analyze high-resolution spectra of the nearby (1.34 pc) stars alpha Cen A (G2 V) and alpha Cen B (K1 V), which were obtained with the Goddard High Resolution Spectrograph on the Hubble Space Telescope. The observations consist of echelle spectra of the Mg II 2800 A and Fe II 2599 A resonance lines and the Lyman-alpha lines of hydrogen and deuterium. The interstellar gas has a velocity (v = - 18.0 +/- 0.2 km/s) consistent with the local flow vector proposed for this line of sight by Lailement & Berlin (1992). The temperature and nonthermal velocity inferred from the Fe II, Mg II, and D I line profiles are T = 5400 +/- 500 K and xi = 1.20 +/- 0.25 km/s, respectively. However, single-component fits to the H I Lyman-alpha lines yield a Doppler parameter (bHI = 11.80 km/s) that implies a significantly warmer temperature of 8350 K, and the velocity of the H I absorption (v = - 15.8 +/- 0.2 km/s) is redshifted by about 2.2 km/s with respect to the Fe II, Mg II, and D I lines. The one-component model of the interstellar gas suggests natural logarithm N base HI = 18.03 +/- 0.01 and D/H = (5.7 +/- 0.2) x 10-6 . These parameters lead to a good fit to the observed spectra, but this model does not explain the higher temperature and redshift of H I relative to the other interstellar lines. The most sensible way to resolve the discrepancy between H(I) and the other lines is to add a second absorption component to the H(I) lines. This second component is hotter (T approx. equals 30,000 K), is redshifted relative to the primary component by 2-4 km/s, and has a column density too low to be detected in the Fe(II), Mg(II), and D(I) lines. We propose that the gas responsible for this component is located near the heliopause, consisting of the heated H I gas from the interstellar medium that is compressed by the solar wind. This so-called 'hydrogen wall' is predicted by recent multifluid gasdynamical models of the interstellar gas and solar wind interaction. Our data provide the first measurements of the temperature and column density of H(I) in the hydrogen wall. After considering the effects that a corresponding hydrogen wall around alpha Cen would have on our analysis, our best estimates for the parameters of the solar hydrogen wall are natural log N(2)(H(I)) = 14.74 +/- 0.24, b(2)(H(I)) = 21.9 +/- 1.7 km/s (corresponding to T = 29,000 +/- 5000 K), and v(2)(H(I)) greater than -16km/s. Unfortunately, the existence of this heated H(I) reduces our ability to compute the H(I) column density of the interstellar medium accurately because, with slight alterations to our assumed stellar Lyman-alpha profiles, we discovered that acceptable two-component fits also exist with natural log N(H(I))approx. 17.6. We, therefore, quote large error bars for the H I column density along the alpha Cen line of sight, natural log N(H(I)) = 17.80 +/- 0.30. For this range in N(H(I)), n(H(I)) = 0.15 /cu.cm (+/- a factor of 2) and D/H = (0.5-1.9) x 10-5. This is the first direct measurement of the H(I) density in a local cloud and allows us to predict the distance from the Sun to the edge of the local cloud along various lines of sight. This range in D/H is consistent with the value D/H = 1.6 x 10-5 previously derived for the Capella and Procyon lines of sight. We cannot tell whether D/H ratio varies or is constant in the local interstellar medium, but we do find that the D(I)/Mg(II) ratio for the alpha Cen line of sight is about 4 times smaller than for the Capella and Procyon lines of sight. Therefore, either D/H or the Mg depletion varies significantly over distance scales of only a few parsecs.

Uncertain sightings and the extinction of the Ivory-billed Woodpecker.

PubMed

Solow, Andrew; Smith, Woollcott; Burgman, Mark; Rout, Tracy; Wintle, Brendan; Roberts, David

2012-02-01

The extinction of a species can be inferred from a record of its sightings. Existing methods for doing so assume that all sightings in the record are valid. Often, however, there are sightings of uncertain validity. To date, uncertain sightings have been treated in an ad hoc way, either excluding them from the record or including them as if they were certain. We developed a Bayesian method that formally accounts for such uncertain sightings. The method assumes that valid and invalid sightings follow independent Poisson processes and use noninformative prior distributions for the rate of valid sightings and for a measure of the quality of uncertain sightings. We applied the method to a recently published record of sightings of the Ivory-billed Woodpecker (Campephilus principalis). This record covers the period 1897-2010 and contains 39 sightings classified as certain and 29 classified as uncertain. The Bayes factor in favor of extinction was 4.03, which constitutes substantial support for extinction. The posterior distribution of the time of extinction has 3 main modes in 1944, 1952, and 1988. The method can be applied to sighting records of other purportedly extinct species. ©2011 Society for Conservation Biology.

Large-Scale Star Formation-Driven Outflows at 1

NASA Astrophysics Data System (ADS)

Lundgren, Britt; Brammer, G.; Van Dokkum, P. G.; Bezanson, R.; Franx, M.; Fumagalli, M.; Momcheva, I. G.; Nelson, E.; Skelton, R.; Wake, D.; Whitaker, K. E.; da Cunha, E.; Erb, D.; Fan, X.; Kriek, M.; Labbe, I.; Marchesini, D.; Patel, S.; Rix, H.; Schmidt, K.; van der Wel, A.

2013-01-01

We present evidence of large-scale outflows from three low-mass star-forming galaxies observed at z=1.24, z=1.35 and z=1.75 in the 3D-HST Survey. Each of these galaxies is located within a projected physical distance of 60 kpc around the sight line to the quasar SDSS J123622.93+621526.6, which exhibits well-separated strong (W>0.8A) MgII absorption systems matching precisely to the redshifts of the three galaxies. We derive the star formation surface densities from the H-alpha emission in the WFC3 G141 grism observations for the galaxies and find that in each case the star formation surface density well-exceeds 0.1 solar mass / yr / kpc^2, the typical threshold for starburst galaxies in the local Universe. From a small but complete parallel census of the 0.650.8A MgII covering fraction of star-forming galaxies at 10.4A MgII absorbing gas around star-forming galaxies may evolve from 2 to the present, consistent with recent observations of an increasing collimation of star formation-driven outflows with time from 3.

Large-scale Star-formation-driven Outflows at 1 < z < 2 in the 3D-HST Survey

NASA Astrophysics Data System (ADS)

Lundgren, Britt F.; Brammer, Gabriel; van Dokkum, Pieter; Bezanson, Rachel; Franx, Marijn; Fumagalli, Mattia; Momcheva, Ivelina; Nelson, Erica; Skelton, Rosalind E.; Wake, David; Whitaker, Katherine; da Cunha, Elizabete; Erb, Dawn K.; Fan, Xiaohui; Kriek, Mariska; Labbé, Ivo; Marchesini, Danilo; Patel, Shannon; Rix, Hans Walter; Schmidt, Kasper; van der Wel, Arjen

2012-11-01

We present evidence of large-scale outflows from three low-mass (log(M */M ⊙) ~ 9.75) star-forming (SFR > 4 M ⊙ yr-1) galaxies observed at z = 1.24, z = 1.35, and z = 1.75 in the 3D-HST Survey. Each of these galaxies is located within a projected physical distance of 60 kpc around the sight line to the quasar SDSS J123622.93+621526.6, which exhibits well-separated strong (W λ2796 r >~ 0.8 Å) Mg II absorption systems matching precisely to the redshifts of the three galaxies. We derive the star formation surface densities from the Hα emission in the WFC3 G141 grism observations for the galaxies and find that in each case the star formation surface density well exceeds 0.1 M ⊙ yr-1 kpc-2, the typical threshold for starburst galaxies in the local universe. From a small but complete parallel census of the 0.65 < z < 2.6 galaxies with H 140 <~ 24 proximate to the quasar sight line, we detect Mg II absorption associated with galaxies extending to physical distances of 130 kpc. We determine that the Wr > 0.8 Å Mg II covering fraction of star-forming galaxies at 1 < z < 2 may be as large as unity on scales extending to at least 60 kpc, providing early constraints on the typical extent of starburst-driven winds around galaxies at this redshift. Our observations additionally suggest that the azimuthal distribution of Wr > 0.4 Å Mg II absorbing gas around star-forming galaxies may evolve from z ~ 2 to the present, consistent with recent observations of an increasing collimation of star-formation-driven outflows with time from z ~ 3.

Wintering habitat model for the North Atlantic Right Whale (Eubalaena glacialis) in the southeastern United States.

PubMed

Gowan, Timothy A; Ortega-Ortiz, Joel G

2014-01-01

The coastal waters off the southeastern United States (SEUS) are a primary wintering ground for the endangered North Atlantic right whale (Eubalaena glacialis), used by calving females along with other adult and juvenile whales. Management actions implemented in this area for the recovery of the right whale population rely on accurate habitat characterization and the ability to predict whale distribution over time. We developed a temporally dynamic habitat model to predict wintering right whale distribution in the SEUS using a generalized additive model framework and aerial survey data from 2003/2004 through 2012/2013. We built upon previous habitat models for right whales in the SEUS and include data from new aerial surveys that extend the spatial coverage of the analysis, particularly in the northern portion of this wintering ground. We summarized whale sightings, survey effort corrected for probability of whale detection, and environmental data at a semimonthly resolution. Consistent with previous studies, sea surface temperature (SST), water depth, and survey year were significant predictors of right whale relative abundance. Additionally, distance to shore, distance to the 22°C SST isotherm, and an interaction between time of year and latitude (to account for the latitudinal migration of whales) were also selected in the analysis presented here. Predictions from the model revealed that the location of preferred habitat differs within and between years in correspondence with variation in environmental conditions. Although cow-calf pairs were rarely sighted in the company of other whales, there was minimal evidence that the preferred habitat of cow-calf pairs was different than that of whale groups without calves at the scale of this study. The results of this updated habitat model can be used to inform management decisions for a migratory species in a dynamic oceanic environment.

Modeling of Ground Deformation and Shallow Surface Waves Generated by Martian Dust Devils and Perspectives for Near-Surface Structure Inversion

NASA Astrophysics Data System (ADS)

Kenda, Balthasar; Lognonné, Philippe; Spiga, Aymeric; Kawamura, Taichi; Kedar, Sharon; Banerdt, William Bruce; Lorenz, Ralph; Banfield, Don; Golombek, Matthew

2017-10-01

We investigated the possible seismic signatures of dust devils on Mars, both at long and short period, based on the analysis of Earth data and on forward modeling for Mars. Seismic and meteorological data collected in the Mojave Desert, California, recorded the signals generated by dust devils. In the 10-100 s band, the quasi-static surface deformation triggered by pressure fluctuations resulted in detectable ground-tilt effects: these are in good agreement with our modeling based on Sorrells' theory. In addition, high-frequency records also exhibit a significant excitation in correspondence to dust devil episodes. Besides wind noise, this signal includes shallow surface waves due to the atmosphere-surface coupling and is used for a preliminary inversion of the near-surface S-wave profile down to 50 m depth. In the case of Mars, we modeled the long-period signals generated by the pressure field resulting from turbulence-resolving Large-Eddy Simulations. For typical dust-devil-like vortices with pressure drops of a couple Pascals, the corresponding horizontal acceleration is of a few nm/s2 for rocky subsurface models and reaches 10-20 nm/s2 for weak regolith models. In both cases, this signal can be detected by the Very-Broad Band seismometers of the InSight/SEIS experiment up to a distance of a few hundred meters from the vortex, the amplitude of the signal decreasing as the inverse of the distance. Atmospheric vortices are thus expected to be detected at the InSight landing site; the analysis of their seismic and atmospheric signals could lead to additional constraints on the near-surface structure, more precisely on the ground compliance and possibly on the seismic velocities.

The Hercules stream as seen by APOGEE-2 South

NASA Astrophysics Data System (ADS)

Hunt, Jason A. S.; Bovy, Jo; Pérez-Villegas, Angeles; Holtzman, Jon A.; Sobeck, Jennifer; Chojnowski, Drew; Santana, Felipe A.; Palicio, Pedro A.; Wegg, Christopher; Gerhard, Ortwin; Almeida, Andrés; Bizyaev, Dmitry; Fernandez-Trincado, Jose G.; Lane, Richard R.; Longa-Peña, Penélope; Majewski, Steven R.; Pan, Kaike; Roman-Lopes, Alexandre

2018-02-01

The Hercules stream is a group of comoving stars in the solar neighbourhood, which can potentially be explained as a signature of either the outer Lindblad resonance (OLR) of a fast Galactic bar or the corotation resonance (CR) of a slower bar. In either case, the feature should be present over a large area of the disc. With the recent commissioning of the APOGEE-2 Southern spectrograph we can search for the Hercules stream at (l, b) = (270°, 0), a direction in which the Hercules stream, if caused by the bar's OLR, would be strong enough to be detected using only the line-of-sight velocities. We clearly detect a narrow, Hercules-like feature in the data that can be traced from the solar neighbourhood to a distance of about 4 kpc. The detected feature matches well the line-of-sight velocity distribution from the fast-bar (OLR) model. Confronting the data with a model where the Hercules stream is caused by the CR of a slower bar leads to a poorer match, as the corotation model does not predict clearly separated modes, possibly because the slow-bar model is too hot.

Looking for Dust-Scattering Light Echoes

NASA Astrophysics Data System (ADS)

Mills, Brianna; Heinz, Sebastian; Corrales, Lia

2018-01-01

Galactic X-ray transient sources such as neutron stars or black holes sometimes undergo an outburst in X-rays. Ring structures have been observed around three such sources, produced by the X-ray photons being scattered by interstellar dust grains along our line of sight. These dust-scattering light echoes have proven to be a useful tool for measuring and constraining Galactic distances, mapping the dust structure of the Milky Way, and determining the dust composition in the clouds producing the echo. Detectable light echoes require a sufficient quantity of dust along our line of sight, as well as bright, short-lived Galactic X-ray flares. Using data from the Monitor of All-Sky X-ray Image (MAXI) on-board the International Space Station, we ran a peak finding algorithm in Python to look for characteristic flare events. Each flare was characterized by its fluence, the integrated flux of the flare over time. We measured the distribution of flare fluences to show how many observably bright flares were recorded by MAXI. This work provides a parent set for dust echo searches in archival X-ray data and will inform observing strategies with current and future X-ray missions such as Athena and Lynx.

Ultraviolet Properties of Halo Coronal Mass Ejections: Doppler Shifts, Angles, Shocks, and Bulk Morphology

NASA Astrophysics Data System (ADS)

Ciaravella, A.; Raymond, J. C.; Kahler, S. W.

2006-11-01

We present UV spectral information for 22 halo or partial halo CMEs observed by UVCS. The CME fronts show broad line profiles, while the line intensities are comparable to the background corona. The Doppler shifts of the front material are generally small, showing that the motion of gas in the fronts is mostly transverse to the line of sight. This indicates that, at least in halo CMEs, the fronts generally correspond to coronal plasma swept up by a shock or compression wave, rather than plasma carried outward by magnetic loops. This favors an ice cream cone (or a spherical shell) model, as opposed to an expanding arcade of loops. We use the line widths to discriminate between shock heating and bulk expansion. Of 14 cases where we detected the CME front, the line broadening in 7 cases can be attributed to shock heating, while in 3 cases it is the line-of-sight component of the CME expansion. For the CME cores we determine the angles between the motion and the plane of the sky, along with the actual heliocentric distances, in order to provide quantitative estimates of projection effects.

Lionfish misidentification circumvents an optimized escape response by prey

PubMed Central

McCormick, Mark I.; Allan, Bridie J. M.

2016-01-01

Invasive lionfish represent an unprecedented problem in the Caribbean basin, where they are causing major changes to foodwebs and habitats through their generalized predation on fishes and invertebrates. To ascertain what makes the red lionfish (Pterois volitans) such a formidable predator, we examined the reaction of a native damselfish prey, the whitetail damsel (Pomacentrus chrysurus), to a repeatable startle stimulus once they had been forewarned of the sight or smell of lionfish. Fast-start responses were compared with prey forewarned of a predatory rockcod (Cephalopholis microprion), a corallivorous butterflyfish (Chaetodon trifasctiatus) and experimental controls. Forewarning of the sight, smell or a combination of the two cues from a rockcod led to reduced escape latencies and higher response distances, speed and maximal speed compared with controls, suggesting that forewarning primed the prey and enabled a more effective escape response. In contrast, forewarning of lionfish did not affect the fast-start kinematics measured, which were the same as in the control and non-predatory butterflyfish treatments. Lionfish appear to be able to circumvent mechanisms commonly used by prey to identify predators and were misclassified as non-predatory, and this is likely to contribute to their success as predators. PMID:27990292

Lionfish misidentification circumvents an optimized escape response by prey.

PubMed

McCormick, Mark I; Allan, Bridie J M

2016-01-01

Invasive lionfish represent an unprecedented problem in the Caribbean basin, where they are causing major changes to foodwebs and habitats through their generalized predation on fishes and invertebrates. To ascertain what makes the red lionfish ( Pterois volitans ) such a formidable predator, we examined the reaction of a native damselfish prey, the whitetail damsel ( Pomacentrus chrysurus ), to a repeatable startle stimulus once they had been forewarned of the sight or smell of lionfish. Fast-start responses were compared with prey forewarned of a predatory rockcod ( Cephalopholis microprion ), a corallivorous butterflyfish ( Chaetodon trifasctiatus ) and experimental controls. Forewarning of the sight, smell or a combination of the two cues from a rockcod led to reduced escape latencies and higher response distances, speed and maximal speed compared with controls, suggesting that forewarning primed the prey and enabled a more effective escape response. In contrast, forewarning of lionfish did not affect the fast-start kinematics measured, which were the same as in the control and non-predatory butterflyfish treatments. Lionfish appear to be able to circumvent mechanisms commonly used by prey to identify predators and were misclassified as non-predatory, and this is likely to contribute to their success as predators.

Inferring the three-dimensional distribution of dust in the Galaxy with a non-parametric method . Preparing for Gaia

NASA Astrophysics Data System (ADS)

Rezaei Kh., S.; Bailer-Jones, C. A. L.; Hanson, R. J.; Fouesneau, M.

2017-02-01

We present a non-parametric model for inferring the three-dimensional (3D) distribution of dust density in the Milky Way. Our approach uses the extinction measured towards stars at different locations in the Galaxy at approximately known distances. Each extinction measurement is proportional to the integrated dust density along its line of sight (LoS). Making simple assumptions about the spatial correlation of the dust density, we can infer the most probable 3D distribution of dust across the entire observed region, including along sight lines which were not observed. This is possible because our model employs a Gaussian process to connect all LoS. We demonstrate the capability of our model to capture detailed dust density variations using mock data and simulated data from the Gaia Universe Model Snapshot. We then apply our method to a sample of giant stars observed by APOGEE and Kepler to construct a 3D dust map over a small region of the Galaxy. Owing to our smoothness constraint and its isotropy, we provide one of the first maps which does not show the "fingers of God" effect.

Exoatmospheric intercepts using zero effort miss steering for midcourse guidance

NASA Astrophysics Data System (ADS)

Newman, Brett

The suitability of proportional navigation, or an equivalent zero effort miss formulation, for exatmospheric intercepts during midcourse guidance, followed by a ballistic coast to the endgame, is addressed. The problem is formulated in terms of relative motion in a general, three dimensional framework. The proposed guidance law for the commanded thrust vector orientation consists of the sum of two terms: (1) along the line of sight unit direction and (2) along the zero effort miss component perpendicular to the line of sight and proportional to the miss itself and a guidance gain. If the guidance law is to be suitable for longer range targeting applications with significant ballistic coasting after burnout, determination of the zero effort miss must account for the different gravitational accelerations experienced by each vehicle. The proposed miss determination techniques employ approximations for the true differential gravity effect and thus, are less accurate than a direct numerical propagation of the governing equations, but more accurate than a baseline determination, which assumes equal accelerations for both vehicles. Approximations considered are constant, linear, quadratic, and linearized inverse square models. Theoretical results are applied to a numerical engagement scenario and the resulting performance is evaluated in terms of the miss distances determined from nonlinear simulation.

Densities and filling factors of the diffuse ionized gas in the Solar neighbourhood

NASA Astrophysics Data System (ADS)

Berkhuijsen, E. M.; Müller, P.

2008-10-01

Aims: We analyse electron densities and filling factors of the diffuse ionized gas (DIG) in the Solar neighbourhood. Methods: We have combined dispersion measures and emission measures towards 38 pulsars at distances known to better than 50%, from which we derived the mean density in clouds, N_c, and their volume filling factor, F_v, averaged along the line of sight. The emission measures were corrected for absorption by dust and contributions from beyond the pulsar distance. Results: The scale height of the electron layer for our sample is 0.93± 0.13 kpc and the midplane electron density is 0.023± 0.004 cm-3, in agreement with earlier results. The average density along the line of sight is < n_e> = 0.018± 0.002 cm-3 and is nearly constant. Since < n_e> = F_vN_c, an inverse relationship between Fv and Nc is expected. We find F_v(N_c) = (0.011± 0.003) N_c-1.20± 0.13, which holds for the ranges N_c= 0.05-1 cm-3 and F_v= 0.4-0.01. Near the Galactic plane the dependence of Fv on Nc is significantly stronger than away from the plane. Fv does not systematically change along or perpendicular to the Galactic plane, but the spread about the mean value of 0.08± 0.02 is considerable. The total pathlength through the ionized regions increases linearly to about 80 pc towards |z| = 1 kpc. Conclusions: Our study of Fv and Nc of the DIG is the first one based on a sample of pulsars with known distances. We confirm the existence of a tight, nearly inverse correlation between Fv and Nc in the DIG. The exact form of this relation depends on the regions in the Galaxy probed by the pulsar sample. The inverse F_v-Nc relation is consistent with a hierarchical, fractal density distribution in the DIG caused by turbulence. The observed near constancy of < n_e> then is a signature of fractal structure in the ionized medium, which is most pronounced outside the thin disk.

A water-vapour giga-maser in the active galaxy TXFS2226-184.

PubMed

Koekemoer, A M; Henkel, C; Greenhill, L J; Dey, A; van Breugel, W; Codella, C; Antonucci, R

1995-12-14

Active galactic nuclei are thought to be powered by gas falling into a massive black hole; the different types of active galaxy may arise because we view them through a thick torus of molecular gas at varying angles of inclination. One way to determine whether the black hole is surrounded by a torus, which would obscure the accretion disk around the black hole along certain lines of sight, is to search for water masers, as these exist only in regions with plentiful molecular gas. Since the first detection of an extra-galactic water maser in 1979, they have come to be associated primarily with active galaxies, and have even been used to probe the mass of the central engine. Here we report the detection of a water giga-maser in the radio galaxy TXFS2226-184. The strength of the emission supports a recently proposed theory of maser pumping that allows for even more powerful masers, which might be detectable at cosmological distances. Water masers may accordingly provide a way to determine distances to galaxies outside the usual distance ladder, providing an independent calibration of the Hubble constant.

A kinematic determination of the structure of the double ring planetary nebula NGC 2392, the Eskimo

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'dell, C.R.; Weiner, L.D.; Chu, Yoyhua

Slit spectra and existing velocity cube data have been used to determine the structure of the double ring PN NGC 2392. The inner shell is a stellar wind-sculpted prolate spheroid with a ratio of axes of 2:1 and the approaching end of the long axis pointed 20 deg from the line of sight in P.A. = 200 deg. The outer ring is caused by an outer disk with density dropping off with distance from the central star and with distance from its plane, which is the same as the equatorial band of high density in the inner shell. The outermore » disk contains a ring of higher density knots at a distance of 16 arcsec and is losing material through free expansion, forming an outer envelope of increasing velocity. Forbidden S II spectra are used to determine the densities in all of the major regions of the nebula. It is argued that the filamentary cores at the centers of the knots seen in the outer ring originate in the sublimation of bodies formed at the same time as the parent star. 26 refs.« less

Experimental investigation of observation error in anuran call surveys

USGS Publications Warehouse

McClintock, B.T.; Bailey, L.L.; Pollock, K.H.; Simons, T.R.

2010-01-01

Occupancy models that account for imperfect detection are often used to monitor anuran and songbird species occurrence. However, presenceabsence data arising from auditory detections may be more prone to observation error (e.g., false-positive detections) than are sampling approaches utilizing physical captures or sightings of individuals. We conducted realistic, replicated field experiments using a remote broadcasting system to simulate simple anuran call surveys and to investigate potential factors affecting observation error in these studies. Distance, time, ambient noise, and observer abilities were the most important factors explaining false-negative detections. Distance and observer ability were the best overall predictors of false-positive errors, but ambient noise and competing species also affected error rates for some species. False-positive errors made up 5 of all positive detections, with individual observers exhibiting false-positive rates between 0.5 and 14. Previous research suggests false-positive errors of these magnitudes would induce substantial positive biases in standard estimators of species occurrence, and we recommend practices to mitigate for false positives when developing occupancy monitoring protocols that rely on auditory detections. These recommendations include additional observer training, limiting the number of target species, and establishing distance and ambient noise thresholds during surveys. ?? 2010 The Wildlife Society.

The "EyeCane", a new electronic travel aid for the blind: Technology, behavior & swift learning.

PubMed

Maidenbaum, Shachar; Hanassy, Shlomi; Abboud, Sami; Buchs, Galit; Chebat, Daniel-Robert; Levy-Tzedek, Shelly; Amedi, Amir

2014-01-01

Independent mobility is one of the most pressing problems facing people who are blind. We present the EyeCane, a new mobility aid aimed at increasing perception of environment beyond what is provided by the traditional White Cane for tasks such as distance estimation, navigation and obstacle detection. The "EyeCane" enhances the traditional White Cane by using tactile and auditory output to increase detectable distance and angles. It circumvents the technical pitfalls of other devices, such as weight, short battery life, complex interface schemes, and slow learning curve. It implements multiple beams to enables detection of obstacles at different heights, and narrow beams to provide active sensing that can potentially increase the user's spatial perception of the environment. Participants were tasked with using the EyeCane for several basic tasks with minimal training. Blind and blindfolded-sighted participants were able to use the EyeCane successfully for distance estimation, simple navigation and simple obstacle detection after only several minutes of training. These results demonstrate the EyeCane's potential for mobility rehabilitation. The short training time is especially important since available mobility training resources are limited, not always available, and can be quite expensive and/or entail long waiting periods.

Compensating Unknown Time-Varying Delay in Opto-Electronic Platform Tracking Servo System.

PubMed

Xie, Ruihong; Zhang, Tao; Li, Jiaquan; Dai, Ming

2017-05-09

This paper investigates the problem of compensating miss-distance delay in opto-electronic platform tracking servo system. According to the characteristic of LOS (light-of-sight) motion, we setup the Markovian process model and compensate this unknown time-varying delay by feed-forward forecasting controller based on robust H∞ control. Finally, simulation based on double closed-loop PI (Proportion Integration) control system indicates that the proposed method is effective for compensating unknown time-varying delay. Tracking experiments on the opto-electronic platform indicate that RMS (root-mean-square) error is 1.253 mrad when tracking 10° 0.2 Hz signal.

Integrating free-space optical communication links with existing WiFi (WiFO) network

NASA Astrophysics Data System (ADS)

Liverman, S.; Wang, Q.; Chu, Y.; Duong, T.; Nguyen-Huu, D.; Wang, S.; Nguyen, T.; Wang, A. X.

2016-02-01

Recently, free-space optical (FSO) systems have generated great interest due to their large bandwidth potential and a line-of-sight physical layer of protection. In this paper, we propose WiFO, a novel hybrid system, FSO downlink and WiFi uplink, which will integrate currently available WiFi infrastructure with inexpensive infrared light emitting diodes. This system takes full advantage of the mobility inherent in WiFi networks while increasing the downlink bandwidth available to each end user. We report the results of our preliminary investigation that show the capabilities of our prototype design in terms of bandwidth, bit error rates, delays and transmission distances.

The Shock and Vibration Bulletin. Part 2. Measurement Techniques and Data Analysis, Dynamic Measurements, Vibration and Acoustics

DTIC Science & Technology

1980-09-01

angular dis- meters ( 3.3 inches). The user supplies t 15 volt regulated turbance when multiplied by a long line-of-sight distance power , and the...chosing these numbers o the vibration power will mostly f+l be allocated to the main resonan - > = f . f ces of the test item in a correct 1 (fV+l-f ) .. I...Generators Data Noraircoustic Mark V Lng EPT 1094B Output Acoustic Power 50 kW 10 KW Air Supply Pressure 827.36 N/m 2 X 103 (120 psig) 275.78 N/m 2 X 103

Thermal analysis of the in-vessel components of the ITER plasma-position reflectometry.

PubMed

Quental, P B; Policarpo, H; Luís, R; Varela, P

2016-11-01

The ITER plasma position reflectometry system measures the edge electron density profile of the plasma, providing real-time supplementary contribution to the magnetic measurements of the plasma-wall distance. Some of the system components will be in direct sight of the plasma and therefore subject to plasma and stray radiation, which may cause excessive temperatures and stresses. In this work, thermal finite element analysis of the antenna and adjacent waveguides is conducted with ANSYS V17 (ANSYS® Academic Research, Release 17.0, 2016). Results allow the identification of critical temperature points, and solutions are proposed to improve the thermal behavior of the system.

Optical image of a cometary nucleus: 1980 flyby of Comet Encke

NASA Technical Reports Server (NTRS)

Wells, W. C.; Benson, R. S.; Anderson, A. D.; Gal, G.

1974-01-01

The feasibility was investigated of obtaining optical images of a cometary nucleus via a flyby of Comet Encke. A physical model of the dust cloud surrounding the nucleus was developed by using available physical data and theoretical knowledge of cometary physics. Using this model and a Mie scattering code, calculations were made of the absolute surface brightness of the dust in the line of sight of the on-board camera and the relative surface brightness of the dust compared to the nucleus. The brightness was calculated as a function of heliocentric distance and for different phase angles (sun-comet-spacecraft angle).

Using satellites to improve civilian aircraft surveillance coverage

NASA Technical Reports Server (NTRS)

Mcgraw, K.

1984-01-01

Surveillance of aircraft is presently accomplished through the use of terrestrial based secondary radar sensors, which are capable of interrogating transponders aboard aircraft. Transponder responses provide the basis for determining radial distance by measuring round-trip signal time while antenna angular position is used to determine azimuthal position. These interrogating radar beams are line-of-sight and thus have their coverage obscured by mountains and tall buildings. The addition of more radar sites is rendered unfeasible by the lack of easy access to the required additional site locations. A possible solution to this problem is to deploy satellites that interrogate transponder-equipped aircraft from a position that provides an unobstructed view.

Determination of the time delay in the case of two-path propagation on the basis of the attenuation characteristics for two adjacent frequencies

NASA Technical Reports Server (NTRS)

Gilroi, H. G.

1979-01-01

Pronounced fading occurring in the line of sight radio links at frequencies below 10 GHz can be traced to the effects of multipath propagation. Modulation disturbances depend on travel time differences between the direct wave and the wave which is reflected at atmospheric layers. A method described for the determination of the time delay is based on an indirect approach which utilizes the difference in fading at various frequencies. The method was employed in measurements involving a distance of 181 km. The results obtained in the measurement are discussed.

On the sighting of unicorns: A variational approach to computing invariant sets in dynamical systems

NASA Astrophysics Data System (ADS)

Junge, Oliver; Kevrekidis, Ioannis G.

2017-06-01

We propose to compute approximations to invariant sets in dynamical systems by minimizing an appropriate distance between a suitably selected finite set of points and its image under the dynamics. We demonstrate, through computational experiments, that this approach can successfully converge to approximations of (maximal) invariant sets of arbitrary topology, dimension, and stability, such as, e.g., saddle type invariant sets with complicated dynamics. We further propose to extend this approach by adding a Lennard-Jones type potential term to the objective function, which yields more evenly distributed approximating finite point sets, and illustrate the procedure through corresponding numerical experiments.

On the sighting of unicorns: A variational approach to computing invariant sets in dynamical systems.

PubMed

Junge, Oliver; Kevrekidis, Ioannis G

2017-06-01

We propose to compute approximations to invariant sets in dynamical systems by minimizing an appropriate distance between a suitably selected finite set of points and its image under the dynamics. We demonstrate, through computational experiments, that this approach can successfully converge to approximations of (maximal) invariant sets of arbitrary topology, dimension, and stability, such as, e.g., saddle type invariant sets with complicated dynamics. We further propose to extend this approach by adding a Lennard-Jones type potential term to the objective function, which yields more evenly distributed approximating finite point sets, and illustrate the procedure through corresponding numerical experiments.

Thermal analysis of the in-vessel components of the ITER plasma-position reflectometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quental, P. B., E-mail: pquental@ipfn.tecnico.ulisboa.pt; Policarpo, H.; Luís, R.

The ITER plasma position reflectometry system measures the edge electron density profile of the plasma, providing real-time supplementary contribution to the magnetic measurements of the plasma-wall distance. Some of the system components will be in direct sight of the plasma and therefore subject to plasma and stray radiation, which may cause excessive temperatures and stresses. In this work, thermal finite element analysis of the antenna and adjacent waveguides is conducted with ANSYS V17 (ANSYS® Academic Research, Release 17.0, 2016). Results allow the identification of critical temperature points, and solutions are proposed to improve the thermal behavior of the system.

Power losses in diffuse ultraviolet optical communications channels.

PubMed

Raptis, Nikos; Pikasis, Evangelos; Syvridis, Dimitris

2016-09-15

One of the most critical parameters in free-space optical communications systems operating in a non-line-of-sight regime are the optical losses. In this Letter, we numerically calculate these losses taking into account the scattering effects using the Monte Carlo simulation technique. The obtained results are compared with experimentally obtained data at 265 nm (solar-blind UV regime). A large set of measurements at distances up to 20 m, for different elevation angles of the transmitter (UV-LEDs) and receiver (photomultiplier tube) and for different atmospheric conditions has been taken for the characterization of the optical communications channel in terms of its loss properties.

X-Ray Dust Tomography: Mapping the Galaxy one X-ray Transient at a Time

NASA Astrophysics Data System (ADS)

Heinz, Sebastian; Corrales, Lia

2018-01-01

Tomography using X-ray light echoes from dust scattering by interstellar clouds is an accurate tool to study the line-of-sight distribution of dust. It can be used to measure distances to molecular clouds and X-ray sources, it can map Galactic structure in dust, and it can be used for precision measurements of dust composition and grain size distribution. Necessary conditions for observing echoes include a suitable X-ray lightcurve and sufficient dust column density to the source. I will discuss a tool set for studying dust echoes and show results obtained for some of the brightest echoes detected to date.

Radiometric Spacecraft Tracking for Deep Space Navigation

NASA Technical Reports Server (NTRS)

Lanyi, Gabor E.; Border, James S.; Shin, Dong K.

2008-01-01

Interplanetary spacecraft navigation relies on three types of terrestrial tracking observables.1) Ranging measures the distance between the observing site and the probe. 2) The line-of-sight velocity of the probe is inferred from Doppler-shift by measuring the frequency shift of the received signal with respect to the unshifted frequency. 3) Differential angular coordinates of the probe with respect to natural radio sources are nominally obtained via a differential delay technique of (Delta) DOR (Delta Differential One-way Ranging). The accuracy of spacecraft coordinate determination depends on the measurement uncertainties associated with each of these three techniques. We evaluate the corresponding sources of error and present a detailed error budget.

THE BOLOCAM GALACTIC PLANE SURVEY. XII. DISTANCE CATALOG EXPANSION USING KINEMATIC ISOLATION OF DENSE MOLECULAR CLOUD STRUCTURES WITH {sup 13}CO(1-0)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ellsworth-Bowers, Timothy P.; Glenn, Jason; Rosolowsky, Erik

2015-01-20

We present an expanded distance catalog for 1710 molecular cloud structures identified in the Bolocam Galactic Plane Survey (BGPS) version 2, representing a nearly threefold increase over the previous BGPS distance catalog. We additionally present a new method for incorporating extant data sets into our Bayesian distance probability density function (DPDF) methodology. To augment the dense-gas tracers (e.g., HCO{sup +}(3-2), NH{sub 3}(1,1)) used to derive line-of-sight velocities for kinematic distances, we utilize the Galactic Ring Survey (GRS) {sup 13}CO(1-0) data to morphologically extract velocities for BGPS sources. The outline of a BGPS source is used to select a region ofmore » the GRS {sup 13}CO data, along with a reference region to subtract enveloping diffuse emission, to produce a line profile of {sup 13}CO matched to the BGPS source. For objects with a HCO{sup +}(3-2) velocity, ≈95% of the new {sup 13}CO(1-0) velocities agree with that of the dense gas. A new prior DPDF for kinematic distance ambiguity (KDA) resolution, based on a validated formalism for associating molecular cloud structures with known objects from the literature, is presented. We demonstrate this prior using catalogs of masers with trigonometric parallaxes and H II regions with robust KDA resolutions. The distance catalog presented here contains well-constrained distance estimates for 20% of BGPS V2 sources, with typical distance uncertainties ≲ 0.5 kpc. Approximately 75% of the well-constrained sources lie within 6 kpc of the Sun, concentrated in the Scutum-Centaurus arm. Galactocentric positions of objects additionally trace out portions of the Sagittarius, Perseus, and Outer arms in the first and second Galactic quadrants, and we also find evidence for significant regions of interarm dense gas.« less

Ranging in Human Sonar: Effects of Additional Early Reflections and Exploratory Head Movements

PubMed Central

Wallmeier, Ludwig; Wiegrebe, Lutz

2014-01-01

Many blind people rely on echoes from self-produced sounds to assess their environment. It has been shown that human subjects can use echolocation for directional localization and orientation in a room, but echo-acoustic distance perception - e.g. to determine one's position in a room - has received little scientific attention, and systematic studies on the influence of additional early reflections and exploratory head movements are lacking. This study investigates echo-acoustic distance discrimination in virtual echo-acoustic space, using the impulse responses of a real corridor. Six blindfolded sighted subjects and a blind echolocation expert had to discriminate between two positions in the virtual corridor, which differed by their distance to the front wall, but not to the lateral walls. To solve this task, participants evaluated echoes that were generated in real time from self-produced vocalizations. Across experimental conditions, we systematically varied the restrictions for head rotations, the subjects' orientation in virtual space and the reference position. Three key results were observed. First, all participants successfully solved the task with discrimination thresholds below 1 m for all reference distances (0.75–4 m). Performance was best for the smallest reference distance of 0.75 m, with thresholds around 20 cm. Second, distance discrimination performance was relatively robust against additional early reflections, compared to other echolocation tasks like directional localization. Third, free head rotations during echolocation can improve distance discrimination performance in complex environmental settings. However, head movements do not necessarily provide a benefit over static echolocation from an optimal single orientation. These results show that accurate distance discrimination through echolocation is possible over a wide range of reference distances and environmental conditions. This is an important functional benefit of human echolocation, which may also play a major role in the calibration of auditory space representations. PMID:25551226

Is the Milky Way's hot halo convectively unstable?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henley, David B.; Shelton, Robin L., E-mail: dbh@physast.uga.edu

2014-03-20

We investigate the convective stability of two popular types of model of the gas distribution in the hot Galactic halo. We first consider models in which the halo density and temperature decrease exponentially with height above the disk. These halo models were created to account for the fact that, on some sight lines, the halo's X-ray emission lines and absorption lines yield different temperatures, implying that the halo is non-isothermal. We show that the hot gas in these exponential models is convectively unstable if γ < 3/2, where γ is the ratio of the temperature and density scale heights. Usingmore » published measurements of γ and its uncertainty, we use Bayes' theorem to infer posterior probability distributions for γ, and hence the probability that the halo is convectively unstable for different sight lines. We find that, if these exponential models are good descriptions of the hot halo gas, at least in the first few kiloparsecs from the plane, the hot halo is reasonably likely to be convectively unstable on two of the three sight lines for which scale height information is available. We also consider more extended models of the halo. While isothermal halo models are convectively stable if the density decreases with distance from the Galaxy, a model of an extended adiabatic halo in hydrostatic equilibrium with the Galaxy's dark matter is on the boundary between stability and instability. However, we find that radiative cooling may perturb this model in the direction of convective instability. If the Galactic halo is indeed convectively unstable, this would argue in favor of supernova activity in the Galactic disk contributing to the heating of the hot halo gas.« less

Observational selection biases in time-delay strong lensing and their impact on cosmography

NASA Astrophysics Data System (ADS)

Collett, Thomas E.; Cunnington, Steven D.

2016-11-01

Inferring cosmological parameters from time-delay strong lenses requires a significant investment of telescope time; it is therefore tempting to focus on the systems with the brightest sources, the highest image multiplicities and the widest image separations. We investigate if this selection bias can influence the properties of the lenses studied and the cosmological parameters inferred. Using an ellipsoidal power-law deflector population, we build a sample of double- and quadruple-image systems. Assuming reasonable thresholds on image separation and flux, based on current lens monitoring campaigns, we find that the typical density profile slopes of monitorable lenses are significantly shallower than the input ensemble. From a sample of quads, we find that this selection function can introduce a 3.5 per cent bias on the inferred time-delay distances if the properties of the input ensemble are (incorrectly) used as priors on the lens model. This bias remains at the 2.4 per cent level when high-resolution imaging of the quasar host is used to precisely infer the properties of individual lenses. We also investigate if the lines of sight for monitorable strong lenses are biased. The expectation value for the line-of-sight convergence is increased by 0.009 (0.004) for quads (doubles) implying a 0.9 per cent (0.4 per cent) bias on H0. We therefore conclude that whilst the properties of typical quasar lenses and their lines of sight do deviate from the global population, the total magnitude of this effect is likely to be a subdominant effect for current analyses, but has the potential to be a major systematic for samples of ˜25 or more lenses.

A case against an X-shaped structure in the Milky Way young bulge

NASA Astrophysics Data System (ADS)

López-Corredoira, Martín

2016-09-01

Context. A number of recent papers have claimed the discovery of an X-shape structure in the bulge of our Galaxy in the population of the red clumps. Aims: We endeavor to analyze the stellar density of bulge stars in the same regions using a different stellar population that is characteristic of the young bulge (≲ 5 Gyr). Particularly, we use F0-F5 main-sequence stars with distances derived through photometric parallax. Methods: We extract these stars from extinction-corrected color-magnitude diagrams in the near-infrared of VISTA-VVV data in some bulge regions and calculate the densities along the line of sight. We take the uncertaintity in the photometric parallax and the contamination of other sources into account, and we see that these errors do not avoid the detection of a possible double peak along some lines of sight as expected for a X-shape bulge if it existed. Results: Only a single peak in the density distribution along the line of sight is observed, so apparently there is no X-shape structure for this population of stars. Nonetheless, the effects of the dispersion of absolute magnitudes in the selected population might be an alternative explanation, although in principle these effects are insufficient to explain this lack of double peak according to our calculations. Conclusions: The results of the present paper do not demonstrate that previous claims of X-shaped bulge using only red clump stars are incorrect, but there are apparently some puzzling questions if we want to maintain the validity of both the red-clump results and the results of this paper.

UAS Satellite Earth Station Emission Limits for Terrestrial System Interference Protection

NASA Technical Reports Server (NTRS)

Kerczewski, Robert J.; Bishop, William D.

2017-01-01

Unmanned aircraft systems (UAS) will have a major impact on future aviation. Medium and large UA operating at altitudes above 3000 feet will require access to non-segregated, that is, controlled airspace. In order for unmanned aircraft to be integrated into the airspace and operate with other commercial aircraft, a very reliable command and control (C2, a. k. a. control and non-payload communications, (CNPC)) link is required. For operations covering large distances or over remote locations, a beyond-line-of-sight (BLOS) CNPC link would need to be implemented through satellite. Significant progress has taken place on several fronts to advance the integration of UAS into controlled airspace, including the recent completion of Minimum Operational Performance Standards (MOPS) for terrestrial line-of-sight (LOS) UAS command and control (C2) links. The development of MOPS for beyond line-of-sight C2 satellite communication links is underway. Meanwhile the allocation of spectrum for UAS C2 by the International Telecommunications Union Radiocommunication Sector (ITU-R) has also progressed. Spectrum for LOS C2 was allocated at the 2012 World Radiocommunication Conference (WRC-12), and for BLOS C2 an allocation was made at WRC-15, under WRC-15 Resolution 155. Resolution 155, however, does not come into effect until several other actions have been completed. One of these required actions is the identification of a power flux density (pfd) limit on the emissions of UAS Ku-Band satellite communications transmitters reaching the ground. The pfd limit is intended to protect terrestrial systems from harmful interference. WRC-19 is expected to finalize the pfd limit. In preparation for WRC-19, analyses of the required pfd limit are on-going, and supporting activities such as propagation modeling are also planned. This paper provides the status of these activities.

Simultaneous Determination of Structure and Event Location Using Body and Surface Wave Measurements at a Single Station: Preparation for Mars Data from the InSight Mission

NASA Astrophysics Data System (ADS)

Panning, M. P.; Banerdt, W. B.; Beucler, E.; Blanchette-Guertin, J. F.; Boese, M.; Clinton, J. F.; Drilleau, M.; James, S. R.; Kawamura, T.; Khan, A.; Lognonne, P. H.; Mocquet, A.; van Driel, M.

2015-12-01

An important challenge for the upcoming InSight mission to Mars, which will deliver a broadband seismic station to Mars along with other geophysical instruments in 2016, is to accurately determine event locations with the use of a single station. Locations are critical for the primary objective of the mission, determining the internal structure of Mars, as well as a secondary objective of measuring the activity of distribution of seismic events. As part of the mission planning process, a variety of techniques have been explored for location of marsquakes and inversion of structure, and preliminary procedures and software are already under development as part of the InSight Mars Quake and Mars Structure Services. One proposed method, involving the use of recordings of multiple-orbit surface waves, has already been tested with synthetic data and Earth recordings. This method has the strength of not requiring an a priori velocity model of Mars for quake location, but will only be practical for larger events. For smaller events where only first orbit surface waves and body waves are observable, other methods are required. In this study, we implement a transdimensional Bayesian inversion approach to simultaneously invert for basic velocity structure and location parameters (epicentral distance and origin time) using only measurements of body wave arrival times and dispersion of first orbit surface waves. The method is tested with synthetic data with expected Mars noise and Earth data for single events and groups of events and evaluated for errors in both location and structural determination, as well as tradeoffs between resolvable parameters and the effect of 3D crustal variations.

An Interactive Software Program to Develop Pianists' Sight-Reading Ability

ERIC Educational Resources Information Center

Tsangari, Victoria

2010-01-01

Musical sight-reading, or sight-playing, is defined as "the ability to play music from a printed score or part for the first time without benefit of practice." While this is the most strict definition of the term, also known as "prima vista" (at first sight), some use the term "sight-reading" even if some rehearsal…

A CGPS Look at the Spiral Structure of the Outer Milky Way. I. Distances and Velocities to Star-forming Regions

NASA Astrophysics Data System (ADS)

Foster, T.; Brunt, C. M.

2015-11-01

We present a new catalog of spectrophotometric distances and line of sight systemic velocities to 103 H ii regions between 90^\\circ ≤slant {\\ell }≤slant 195^\\circ (longitude quadrants II and part of III). Two new velocities for each region are independently measured using 1 arcmin resolution 21 cm H i and 2.6 mm 12CO line maps (from the Canadian Galactic Plane Survey and Five College Radio Astronomy Observatory Outer Galaxy Surveys) that show where gaseous shells are observed around the periphery of the ionized gas. Known and neighboring O- and B-type stars with published UBV photometry and MK classifications are overlaid onto 21 cm continuum maps, and those stars observed within the boundary of the H ii emission (and whose distance is not more than three times the standard deviation of the others) are used to calculate new mean stellar distances to each of the 103 nebulae. Using this approach of excluding distance outliers from the mean distance to a group of many stars in each H ii region lessens the impact of anomalous reddening for certain individuals. The standard deviation of individual stellar distances in a cluster is typically 20% per stellar distance, and the error in the mean distance to the cluster is typically ±10%. Final mean distances of nine common objects with very long baseline interferometry parallax distances show a 1:1 correspondence. Further, comparison with previous catalogs of H ii regions in these quadrants shows a 50% reduction in scatter for the distance to Perseus spiral arm objects in the same region, and a reduction by ˜1/\\sqrt{2} in scatter around a common angular velocity relative to the Sun {{Ω }}-{{{Ω }}}0(km s-1 kpc-1). The purpose of the catalog is to provide a foundation for more detailed large-scale Galactic spiral structure and dynamics (rotation curve, density wave streaming) studies in the 2nd and 3rd quadrants, which from the Sun’s location is the most favorably viewed section of the Galaxy.

A map of dust reddening to 4.5 kpc from Pan-STARRS1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schlafly, E. F.; Rix, H.-W.; Martin, N. F.

2014-07-01

We present a map of the dust reddening to 4.5 kpc derived from Pan-STARRS1 stellar photometry. The map covers almost the entire sky north of declination –30° at a resolution of 7'-14', and is based on the estimated distances and reddenings to more than 500 million stars. The technique is designed to map dust in the Galactic plane, where many other techniques are stymied by the presence of multiple dust clouds at different distances along each line of sight. This reddening-based dust map agrees closely with the Schlegel et al. (SFD) far-infrared emission-based dust map away from the Galactic plane,more » and the most prominent differences between the two maps stem from known limitations of SFD in the plane. We also compare the map with Planck, finding likewise good agreement in general at high latitudes. The use of optical data from Pan-STARRS1 yields reddening uncertainty as low as 25 mmag E(B – V).« less

Short-sighted confession decisions: the role of uncertain and delayed consequences.

PubMed

Yang, Yueran; Madon, Stephanie; Guyll, Max

2015-02-01

Suspects have a propensity to focus on short-term contingencies, giving disproportionate weight to the proximal consequences that are delivered by police during an interrogation, and too little consideration to the distal (and often more severe) consequences that may be levied by the judicial system if they are convicted. In this research, the authors examined whether the perceived uncertainty and temporal distance of distal consequences contribute to this propensity. Using the repetitive question paradigm (Madon et al., 2012), participants (N = 209) were interviewed about 20 prior criminal and unethical behaviors and were required to admit or deny each one. Participants' denials and admissions were paired with both a proximal consequence and a distal consequence, respectively. Results indicated that the distal consequence had less impact on participants' admission decisions when it was uncertain and temporally remote. These results provide evidence that the perceived uncertainty and temporal distance of future punishment are key factors that lead suspects to confess to crimes in exchange for short-term gains.

An Investigation of Multipath Effects on the GPS System During Auto-Rendezvous and Capture

NASA Technical Reports Server (NTRS)

Richie, James E.; Forest, Francis W.

1995-01-01

The proposed use of a Cargo Transport Vehicle (CTV) to carry hardware to the Space Station Freedom (SSF) during the construction phase of the SSF project requires remote maneuvering of the CTV. The CTV is not a manned vehicle. Obtaining the relative positions of the CTV and SSF for remote auto-rendezvous and capture (AR&C) scenarios will rely heavily on the Global Positioning System (GPS). The GPS system is expected to guide the CTV up to a distance of 100 to 300 meters from the SSF. At some point within this range, an optical docking system will take over the remote guidance for capture. During any remote guidance by GPS it is possible that significant multipath signals may be caused by large objects in the vicinity of the module being remotely guided. This could alter the position obtained by the GPS system from the actual position. Due to the nature of the GPS signals, it has been estimated that if the difference in distance between the Line of Sight (LOS) path and the multipath is greater than 300 meters, the GPS system is capable of discriminating between the direct signal and the reflected (or multipath) signal. However, if the path difference is less than 300 meters, one must be concerned. This report details the work accomplished by the Electromagnetic Simulations Laboratory at Marquette University over the period December 1993 to May 1995. This work is an investigation of the strength and phase of a multipath signal arriving at the CTV relative to the direct or line of sight (LOS) signal. The signal originates at a GPS satellite in half geo-stationary orbit and takes two paths to the CTV: (1) the direct or LOS path from the GPS satellite to the CTV; and (2) a scattered path from the GPS satellite to the SSF module and then to the CTV. The scattering from a cylinder has been computed using the physical optics approximation for the current. No other approximations or assumptions have been made including no assumptions regarding the far field or Fresnel field approximations. The integrations required to obtain the scattered field have been computed numerically using an N dimensional Romberg integration. The total scattered electric field is then projected onto the RCP component in the direction of propagation only. The direct or line of sight signal is then used to compute the relative strength and phase of the scattered field. The trajectory of the CTV has been parameterized into 4,214 points that are calculated for each of the geometries investigated. The motion of the CTV between points is small enough for the magnitude data (dB down from direct signal) to appear very smooth; however, because of the distances and wavelengths involved, the phase of the scattered field relative to the direct signal varies very rapidly.

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

Stu Spath, InSight program manager, Lockheed Martin Space, left, and Tom Hoffman, InSight project manager, NASA JPL, discuss NASA's InSight mission during a prelaunch media briefing, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

A summary of research investigating echolocation abilities of blind and sighted humans.

PubMed

Kolarik, Andrew J; Cirstea, Silvia; Pardhan, Shahina; Moore, Brian C J

2014-04-01

There is currently considerable interest in the consequences of loss in one sensory modality on the remaining senses. Much of this work has focused on the development of enhanced auditory abilities among blind individuals, who are often able to use sound to navigate through space. It has now been established that many blind individuals produce sound emissions and use the returning echoes to provide them with information about objects in their surroundings, in a similar manner to bats navigating in the dark. In this review, we summarize current knowledge regarding human echolocation. Some blind individuals develop remarkable echolocation abilities, and are able to assess the position, size, distance, shape, and material of objects using reflected sound waves. After training, normally sighted people are also able to use echolocation to perceive objects, and can develop abilities comparable to, but typically somewhat poorer than, those of blind people. The underlying cues and mechanisms, operable range, spatial acuity and neurological underpinnings of echolocation are described. Echolocation can result in functional real life benefits. It is possible that these benefits can be optimized via suitable training, especially among those with recently acquired blindness, but this requires further study. Areas for further research are identified. Copyright © 2014 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vanderveld, R. Ali; Flanagan, Eanna E.; Wasserman, Ira

Recently, there have been suggestions that the Type Ia supernova data can be explained using only general relativity and cold dark matter with no dark energy. In 'Swiss cheese' models of the Universe, the standard Friedmann-Robertson-Walker picture is modified by the introduction of mass-compensating spherical inhomogeneities, typically described by the Lemaitre-Tolman-Bondi metric. If these inhomogeneities correspond to underdense cores surrounded by mass-compensating overdense shells, then they can modify the luminosity distance-redshift relation in a way that can mimic accelerated expansion. It has been argued that this effect could be large enough to explain the supernova data without introducing dark energymore » or modified gravity. We show that the large apparent acceleration seen in some models can be explained in terms of standard weak field gravitational lensing together with insufficient randomization of void locations. The underdense regions focus the light less than the homogeneous background, thus dimming supernovae in a way that can mimic the effects of acceleration. With insufficient randomization of the spatial location of the voids and of the lines of sight, coherent defocusing can lead to anomalously large demagnification effects. We show that a proper randomization of the voids and lines of sight reduces the effect to the point that it can no longer explain the supernova data.« less

The effect of buildings on acoustic pulse propagation in an urban environment.

PubMed

Albert, Donald G; Liu, Lanbo

2010-03-01

Experimental measurements were conducted using acoustic pulse sources in a full-scale artificial village to investigate the reverberation, scattering, and diffraction produced as acoustic waves interact with buildings. These measurements show that a simple acoustic source pulse is transformed into a complex signature when propagating through this environment, and that diffraction acts as a low-pass filter on the acoustic pulse. Sensors located in non-line-of-sight (NLOS) positions usually recorded lower positive pressure maxima than sensors in line-of-sight positions. Often, the first arrival on a NLOS sensor located around a corner was not the largest arrival, as later reflection arrivals that traveled longer distances without diffraction had higher amplitudes. The waveforms are of such complexity that human listeners have difficulty identifying replays of the signatures generated by a single pulse, and the usual methods of source location based on the direction of arrivals may fail in many cases. Theoretical calculations were performed using a two-dimensional finite difference time domain (FDTD) method and compared to the measurements. The predicted peak positive pressure agreed well with the measured amplitudes for all but two sensor locations directly behind buildings, where the omission of rooftop ray paths caused the discrepancy. The FDTD method also produced good agreement with many of the measured waveform characteristics.

Extraction and analysis of the image in the sight field of comparison goniometer to measure IR mirrors assembly

NASA Astrophysics Data System (ADS)

Wang, Zhi-shan; Zhao, Yue-jin; Li, Zhuo; Dong, Liquan; Chu, Xuhong; Li, Ping

2010-11-01

The comparison goniometer is widely used to measure and inspect small angle, angle difference, and parallelism of two surfaces. However, the common manner to read a comparison goniometer is to inspect the ocular of the goniometer by one eye of the operator. To read an old goniometer that just equips with one adjustable ocular is a difficult work. In the fabrication of an IR reflecting mirrors assembly, a common comparison goniometer is used to measure the angle errors between two neighbor assembled mirrors. In this paper, a quick reading technique image-based for the comparison goniometer used to inspect the parallelism of mirrors in a mirrors assembly is proposed. One digital camera, one comparison goniometer and one set of computer are used to construct a reading system, the image of the sight field in the comparison goniometer will be extracted and recognized to get the angle positions of the reflection surfaces to be measured. In order to obtain the interval distance between the scale lines, a particular technique, left peak first method, based on the local peak values of intensity in the true color image is proposed. A program written in VC++6.0 has been developed to perform the color digital image processing.

Galactic Forces Rule the Dynamics of Milky Way Dwarf Galaxies

NASA Astrophysics Data System (ADS)

Hammer, Francois; Yang, Yanbin; Arenou, Frederic; Babusiaux, Carine; Wang, Jianling; Puech, Mathieu; Flores, Hector

2018-06-01

Dwarf galaxies populating the Galactic halo are assumed to host the largest fractions of dark matter, as calculated from their velocity dispersions. Their major axes are preferentially aligned with the Vast Polar Structure (VPOS) that is perpendicular to the Galactic disk, and we find their velocity gradients aligned as well. This finding results in a probability of random occurrence for the VPOS as low as ∼10‑5. It suggests that tidal forces exerted by the Milky Way are distorting dwarf galaxies. Here we demonstrate on the basis of the impulse approximation that the Galactic gravitational acceleration induces the dwarf line-of-sight velocity dispersion, which is also evidenced by strong dependences between both quantities. Since this result is valid for any dwarf mass value, it implies that dark matter estimates in Milky Way dwarfs cannot be deduced from the product of their radius to the square of their line-of-sight velocity dispersion. This questions the high dark matter fractions reported for these evanescent systems, and the universally adopted total-to-stellar mass relationship in the dwarf regime. It suggests that many dwarfs are at their first passage and are dissolving into the Galactic halo. This gives rise to a promising method to estimate the Milky Way total mass profile at large distances.

NLOS Correction/Exclusion for GNSS Measurement Using RAIM and City Building Models.

PubMed

Hsu, Li-Ta; Gu, Yanlei; Kamijo, Shunsuke

2015-07-17

Currently, global navigation satellite system (GNSS) receivers can provide accurate and reliable positioning service in open-field areas. However, their performance in the downtown areas of cities is still affected by the multipath and none-line-of-sight (NLOS) receptions. This paper proposes a new positioning method using 3D building models and the receiver autonomous integrity monitoring (RAIM) satellite selection method to achieve satisfactory positioning performance in urban area. The 3D building model uses a ray-tracing technique to simulate the line-of-sight (LOS) and NLOS signal travel distance, which is well-known as pseudorange, between the satellite and receiver. The proposed RAIM fault detection and exclusion (FDE) is able to compare the similarity between the raw pseudorange measurement and the simulated pseudorange. The measurement of the satellite will be excluded if the simulated and raw pseudoranges are inconsistent. Because of the assumption of the single reflection in the ray-tracing technique, an inconsistent case indicates it is a double or multiple reflected NLOS signal. According to the experimental results, the RAIM satellite selection technique can reduce by about 8.4% and 36.2% the positioning solutions with large errors (solutions estimated on the wrong side of the road) for the 3D building model method in the middle and deep urban canyon environment, respectively.

A survey of possible missions to the periodic comets in the interval 1974 - 2010

NASA Technical Reports Server (NTRS)

Bender, D. F.

1974-01-01

Catalogs are developed to survey the mission possibilities for the short period comets. In the first the physical and pertinent orbital characteristics are given for 65 short period comets. The second catalog is one containing the predicted perihelia for each of the 65 comets between 1974 and 2010. Geometry is included to indicate feasibility of Earth-based observation and sighting within 100 days of perihelion. The comets are divided on the basis of size and activity into three groups from the data in the first catalog: primary, secondary and low interest. The perihelia are separated into two groups: satisfactory and not satisfactory on the basis of earth-comet distance.

Images by the vineyard: images of addiction and substance users in the media and other culture sites/sights.

PubMed

Allamani, Allaman; Mattiacci, Silvia

2015-03-01

This article constitutes a discovery journey into the world of drinking images, the pleasures and harms related to consuming alcoholic beverages, as well as the relationships between drinking and spirituality. These aspects are described historically and globally, over time through a series of snapshots and mini-discussions about both visual and mental images from art, classical literature and operatic music.The images are interpreted according to how they represent the drinking culture within which they were created and sustained, and how they are able to involve the spectator and the user in terms of either empathizing, accepting and including or distancing, stigmatizing and marginalizing the user.

Structure and other properties of Jupiter's distant magnetotail

NASA Technical Reports Server (NTRS)

Lepping, R. P.; Desch, M. D.; Klein, L. W.; Sittler, E. C., Jr.; Sullivan, J. D.; Kurth, W. S.; Behannon, K. W.

1983-01-01

Analyses of data from Voyager 2 experiments provide evidence for, and characteristics of, a Jovian magnetotail extending at least to 9,000 Jovian radii from the planet. During approximately (25 day) periodic sightings of the tail, the magnetic field tended to point radially towards or away from Jupiter, indicating preservation to large distances of the bipolar, lobe like structure observed near the planet. This periodicity, along with various properties of the solar wind at this time, indicates that the tail is apparently influenced by recurrent solar wind features. Anomalous magnetic fields, not aligned with the nominal tail axis, also exist within the tail, especially in the low density, central (core) region, indicating some complexity of internal structure.

Towards a Dynamic Model of Skills Involved in Sight Reading Music

ERIC Educational Resources Information Center

Kopiez, Reinhard; Lee, Ji In

2006-01-01

This study investigates the relationship between selected predictors of achievement in playing unrehearsed music (sight reading) and the changing complexity of sight reading tasks. The question under investigation is, how different variables gain or lose significance as sight reading stimuli become more difficult. Fifty-two piano major graduates…

Sight-Singing: Ten Years of Published Research

ERIC Educational Resources Information Center

Kuehne, Jane M.

2010-01-01

The purpose of this article was to review published research on sight-singing from the past 10 years, 1998-2008. Several authors published research in various areas in sight-singing. These included festival availability and participation, time use in sight-singing adjudication, method and materials, strategies of successful students, assessing…

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT, KMC CONTROLS, INC. SLE-1001 SIGHT GLASS MONITOR

EPA Science Inventory

The Environmental Technology Verification report discusses the technology and performance of the KMC SLE-1001 Sight Glass Monitor manufactured by KMC Controls, Inc. The sight glass monitor (SGM) fits over the sight glass that may be installed in a refrigeration system for the pur...

Recognition of Rapid Speech by Blind and Sighted Older Adults

ERIC Educational Resources Information Center

Gordon-Salant, Sandra; Friedman, Sarah A.

2011-01-01

Purpose: To determine whether older blind participants recognize time-compressed speech better than older sighted participants. Method: Three groups of adults with normal hearing participated (n = 10/group): (a) older sighted, (b) older blind, and (c) younger sighted listeners. Low-predictability sentences that were uncompressed (0% time…

The alpha Centauri Line of Sight: D/H Ratio, Physical Properties of Local Interstellar Gas, and Measurement of Heated Hydrogen (The 'Hydrogen Wall') Near the Heliopause

NASA Technical Reports Server (NTRS)

Linsky, Jeffrey L.; Wood, Brian E.

1996-01-01

We analyze high-resolution spectra of the nearby (1.34 pc) stars alpha Cen A (G2 V) and alpha Cen B (K1 V), which were obtained with the Goddard High Resolution Spectrograph on the Hubble Space Telescope. The observations consist of echelle spectra of the Mg II 2800 A and Fe II 2599 A resonance lines and the Lyman-alpha lines of hydrogen and deuterium. The interstellar gas has a velocity (v = - 18.0 +/- 0.2 km/s) consistent with the local flow vector proposed for this line of sight by Lailement & Berlin (1992). The temperature and nonthermal velocity inferred from the Fe II, Mg II, and D I line profiles are T = 5400 +/- 500 K and xi = 1.20 +/- 0.25 km/s, respectively. However, single-component fits to the H I Lyman-alpha lines yield a Doppler parameter (b(sub HI) = 11.80 km/s) that implies a significantly warmer temperature of 8350 K, and the velocity of the H I absorption (v = - 15.8 +/- 0.2 km/s) is redshifted by about 2.2 km/s with respect to the Fe II, Mg II, and D I lines. The one-component model of the interstellar gas suggests natural logarithm N base HI = 18.03 +/- 0.01 and D/H = (5.7 +/- 0.2) x 10(exp -6) . These parameters lead to a good fit to the observed spectra, but this model does not explain the higher temperature and redshift of H I relative to the other interstellar lines. The most sensible way to resolve the discrepancy between H(I) and the other lines is to add a second absorption component to the H(I) lines. This second component is hotter (T approx. equals 30,000 K), is redshifted relative to the primary component by 2-4 km/s, and has a column density too low to be detected in the Fe(II), Mg(II), and D(I) lines. We propose that the gas responsible for this component is located near the heliopause, consisting of the heated H I gas from the interstellar medium that is compressed by the solar wind. This so-called 'hydrogen wall' is predicted by recent multifluid gasdynamical models of the interstellar gas and solar wind interaction. Our data provide the first measurements of the temperature and column density of H(I) in the hydrogen wall. After considering the effects that a corresponding hydrogen wall around alpha Cen would have on our analysis, our best estimates for the parameters of the solar hydrogen wall are natural log N(sup (2))(H(I)) = 14.74 +/- 0.24, b(sup (2))(H(I)) = 21.9 +/- 1.7 km/s (corresponding to T = 29,000 +/- 5000 K), and v(sup (2))(H(I)) greater than -16km/s. Unfortunately, the existence of this heated H(I) reduces our ability to compute the H(I) column density of the interstellar medium accurately because, with slight alterations to our assumed stellar Lyman-alpha profiles, we discovered that acceptable two-component fits also exist with natural log N(H(I))approx. 17.6. We, therefore, quote large error bars for the H I column density along the alpha Cen line of sight, natural log N(H(I)) = 17.80 +/- 0.30. For this range in N(H(I)), n(H(I)) = 0.15 /cu.cm (+/- a factor of 2) and D/H = (0.5-1.9) x 10(exp -5). This is the first direct measurement of the H(I) density in a local cloud and allows us to predict the distance from the Sun to the edge of the local cloud along various lines of sight. This range in D/H is consistent with the value D/H = 1.6 x 10(exp -5) previously derived for the Capella and Procyon lines of sight. We cannot tell whether D/H ratio varies or is constant in the local interstellar medium, but we do find that the D(I)/Mg(II) ratio for the alpha Cen line of sight is about 4 times smaller than for the Capella and Procyon lines of sight. Therefore, either D/H or the Mg depletion varies significantly over distance scales of only a few parsecs.

Results of Skylab experiment T00-2, manual navigation sightings

NASA Technical Reports Server (NTRS)

Randle, R. J.

1976-01-01

An analysis of navigation data collected using a hand-held space sextant on the second and third manned Skylab missions was presented. From performance data and astronaut comments it was determined that: (1) the space sextant, the sighting station, and the sighting techniques require modification; (2) the sighting window must be of good optical quality; (3) astronaut performance was stable over long mission time; and (4) sightings made with a hand-held sextant were accurate and precise enough for reliable interplanetary manual navigation.

Flow visualization of mast-mounted-sight/main rotor aerodynamic interactions

NASA Technical Reports Server (NTRS)

Ghee, Terence A.; Kelley, Henry L.

1993-01-01

Flow visualization tests were conducted on a 27 percent-scale AH-64 attack helicopter model fitted with various mast-mounted-sight configurations in an attempt to identify the cause of adverse vibration encountered during full-scale flight tests of an Apache/Longbow configuration. The tests were conducted at the NASA Langley Research Center in the 14- by 22-Foot Subsonic Tunnel. A symmetric and an asymmetric mast-mounted-sight oriented at several skew angles were tested at forward and rearward flight speeds of 30 and 45 knots. A laser light sheet seeded with vaporized propylene glycol was used to visualize the wake of the sight in planes parallel and perpendicular to the freestream flow. Analysis of the flow visualization data identified the frequency of the wake shed from the sight, the angle-of-attack at the sight, and the location where the sight wake crossed the rotor plane. Differences in wake structure were observed between the various sight configurations and slew angles. Postulations into the cause of the adverse vibration found in flight test are given along with considerations for future tests.

Assessing uncertainty in sighting records: an example of the Barbary lion.

PubMed

Lee, Tamsin E; Black, Simon A; Fellous, Amina; Yamaguchi, Nobuyuki; Angelici, Francesco M; Al Hikmani, Hadi; Reed, J Michael; Elphick, Chris S; Roberts, David L

2015-01-01

As species become rare and approach extinction, purported sightings can be controversial, especially when scarce management resources are at stake. We consider the probability that each individual sighting of a series is valid. Obtaining these probabilities requires a strict framework to ensure that they are as accurately representative as possible. We used a process, which has proven to provide accurate estimates from a group of experts, to obtain probabilities for the validation of 32 sightings of the Barbary lion. We consider the scenario where experts are simply asked whether a sighting was valid, as well as asking them to score the sighting based on distinguishablity, observer competence, and verifiability. We find that asking experts to provide scores for these three aspects resulted in each sighting being considered more individually, meaning that this new questioning method provides very different estimated probabilities that a sighting is valid, which greatly affects the outcome from an extinction model. We consider linear opinion pooling and logarithm opinion pooling to combine the three scores, and also to combine opinions on each sighting. We find the two methods produce similar outcomes, allowing the user to focus on chosen features of each method, such as satisfying the marginalisation property or being externally Bayesian.

Performance Analysis of Millimeter-Wave Multi-hop Machine-to-Machine Networks Based on Hop Distance Statistics

PubMed Central

2018-01-01

As an intrinsic part of the Internet of Things (IoT) ecosystem, machine-to-machine (M2M) communications are expected to provide ubiquitous connectivity between machines. Millimeter-wave (mmWave) communication is another promising technology for the future communication systems to alleviate the pressure of scarce spectrum resources. For this reason, in this paper, we consider multi-hop M2M communications, where a machine-type communication (MTC) device with the limited transmit power relays to help other devices using mmWave. To be specific, we focus on hop distance statistics and their impacts on system performances in multi-hop wireless networks (MWNs) with directional antenna arrays in mmWave for M2M communications. Different from microwave systems, in mmWave communications, wireless channel suffers from blockage by obstacles that heavily attenuate line-of-sight signals, which may result in limited per-hop progress in MWNs. We consider two routing strategies aiming at different types of applications and derive the probability distributions of their hop distances. Moreover, we provide their baseline statistics assuming the blockage-free scenario to quantify the impact of blockages. Based on the hop distance analysis, we propose a method to estimate the end-to-end performances (e.g., outage probability, hop count, and transmit energy) of the mmWave MWNs, which provides important insights into mmWave MWN design without time-consuming and repetitive end-to-end simulation. PMID:29329248

Effects of changes in size, speed and distance on the perception of curved 3D trajectories

PubMed Central

Zhang, Junjun; Braunstein, Myron L.; Andersen, George J.

2012-01-01

Previous research on the perception of 3D object motion has considered time to collision, time to passage, collision detection and judgments of speed and direction of motion, but has not directly studied the perception of the overall shape of the motion path. We examined the perception of the magnitude of curvature and sign of curvature of the motion path for objects moving at eye level in a horizontal plane parallel to the line of sight. We considered two sources of information for the perception of motion trajectories: changes in angular size and changes in angular speed. Three experiments examined judgments of relative curvature for objects moving at different distances. At the closest distance studied, accuracy was high with size information alone but near chance with speed information alone. At the greatest distance, accuracy with size information alone decreased sharply but accuracy for displays with both size and speed information remained high. We found similar results in two experiments with judgments of sign of curvature. Accuracy was higher for displays with both size and speed information than with size information alone, even when the speed information was based on parallel projections and was not informative about sign of curvature. For both magnitude of curvature and sign of curvature judgments, information indicating that the trajectory was curved increased accuracy, even when this information was not directly relevant to the required judgment. PMID:23007204

Insensitivity of The Distance Ladder Hubble Constant Determination to Cepheid Calibration Modeling Choices

NASA Astrophysics Data System (ADS)

Follin, B.; Knox, L.

2018-03-01

Recent determination of the Hubble constant via Cepheid-calibrated supernovae by Riess et al. (2016) (R16) find ˜3σ tension with inferences based on cosmic microwave background temperature and polarization measurements from Planck. This tension could be an indication of inadequacies in the concordance ΛCDM model. Here we investigate the possibility that the discrepancy could instead be due to systematic bias or uncertainty in the Cepheid calibration step of the distance ladder measurement by R16. We consider variations in total-to-selective extinction of Cepheid flux as a function of line-of-sight, hidden structure in the period-luminosity relationship, and potentially different intrinsic colour distributions of Cepheids as a function of host galaxy. Considering all potential sources of error, our final determination of H0 = 73.3 ± 1.7 km/s/Mpc (not including systematic errors from the treatment of geometric distances or Type Ia Supernovae) shows remarkable robustness and agreement with R16. We conclude systematics from the modelling of Cepheid photometry, including Cepheid selection criteria, cannot explain the observed tension between Cepheid-variable and CMB-based inferences of the Hubble constant. Considering a `model-independent' approach to relating Cepheids in galaxies with known distances to Cepheids in galaxies hosting a Type Ia supernova and finding agreement with the R16 result, we conclude no generalization of the model relating anchor and host Cepheid magnitude measurements can introduce significant bias in the H0 inference.

The mean free path of hydrogen ionizing photons during the epoch of reionization

NASA Astrophysics Data System (ADS)

Rahmati, Alireza; Schaye, Joop

2018-05-01

We use the Aurora radiation-hydrodynamical simulations to study the mean free path (MFP) for hydrogen ionizing photons during the epoch of reionization. We directly measure the MFP by averaging the distance 1 Ry photons travel before reaching an optical depth of unity along random lines-of-sight. During reionization the free paths tend to end in neutral gas with densities near the cosmic mean, while after reionization the end points tend to be overdense but highly ionized. Despite the increasing importance of discrete, over-dense systems, the cumulative contribution of systems with NHI ≲ 1016.5 cm-2 suffices to drive the MFP at z ≈ 6, while at earlier times higher column densities are more important. After reionization the typical size of HI systems is close to the local Jeans length, but during reionization it is much larger. The mean free path for photons originating close to galaxies, {MFP_{gal}}, is much smaller than the cosmic MFP. After reionization this enhancement can remain significant up to starting distances of ˜1 comoving Mpc. During reionization, however, {MFP_{gal}} for distances ˜102 - 103 comoving kpc typically exceeds the cosmic MFP. These findings have important consequences for models that interpret the intergalactic MFP as the distance escaped ionizing photons can travel from galaxies before being absorbed and may cause them to under-estimate the required escape fraction from galaxies, and/or the required emissivity of ionizing photons after reionization.

Performance Analysis of Millimeter-Wave Multi-hop Machine-to-Machine Networks Based on Hop Distance Statistics.

PubMed

Jung, Haejoon; Lee, In-Ho

2018-01-12

As an intrinsic part of the Internet of Things (IoT) ecosystem, machine-to-machine (M2M) communications are expected to provide ubiquitous connectivity between machines. Millimeter-wave (mmWave) communication is another promising technology for the future communication systems to alleviate the pressure of scarce spectrum resources. For this reason, in this paper, we consider multi-hop M2M communications, where a machine-type communication (MTC) device with the limited transmit power relays to help other devices using mmWave. To be specific, we focus on hop distance statistics and their impacts on system performances in multi-hop wireless networks (MWNs) with directional antenna arrays in mmWave for M2M communications. Different from microwave systems, in mmWave communications, wireless channel suffers from blockage by obstacles that heavily attenuate line-of-sight signals, which may result in limited per-hop progress in MWNs. We consider two routing strategies aiming at different types of applications and derive the probability distributions of their hop distances. Moreover, we provide their baseline statistics assuming the blockage-free scenario to quantify the impact of blockages. Based on the hop distance analysis, we propose a method to estimate the end-to-end performances (e.g., outage probability, hop count, and transmit energy) of the mmWave MWNs, which provides important insights into mmWave MWN design without time-consuming and repetitive end-to-end simulation.

Insensitivity of the distance ladder Hubble constant determination to Cepheid calibration modelling choices

NASA Astrophysics Data System (ADS)

Follin, B.; Knox, L.

2018-07-01

Recent determination of the Hubble constant via Cepheid-calibrated supernovae by Riess et al.find ˜3σ tension with inferences based on cosmic microwave background (CMB) temperature and polarization measurements from Planck. This tension could be an indication of inadequacies in the concordance Λcold dark matter model. Here, we investigate the possibility that the discrepancy could instead be due to systematic bias or uncertainty in the Cepheid calibration step of the distance ladder measurement by Riess et al. We consider variations in total-to-selective extinction of Cepheid flux as a function of line of sight, hidden structure in the period-luminosity relationship, and potentially different intrinsic colour distributions of Cepheids as a function of host galaxy. Considering all potential sources of error, our final determination of H0 = 73.3 ± 1.7 km s-1Mpc-1 (not including systematic errors from the treatment of geometric distances or Type Ia supernovae) shows remarkable robustness and agreement with Riess et al. We conclude systematics from the modelling of Cepheid photometry, including Cepheid selection criteria, cannot explain the observed tension between Cepheid-variable and CMB-based inferences of the Hubble constant. Considering a `model-independent' approach to relating Cepheids in galaxies with known distances to Cepheids in galaxies hosting a Type Ia supernova and finding agreement with the Riess et al. result, we conclude no generalization of the model relating anchor and host Cepheid magnitude measurements can introduce significant bias in the H0 inference.

Archiving InSight Lander Science Data Using PDS4 Standards

NASA Astrophysics Data System (ADS)

Stein, T.; Guinness, E. A.; Slavney, S.

2017-12-01

The InSight Mars Lander is scheduled for launch in 2018, and science data from the mission will be archived in the NASA Planetary Data System (PDS) using the new PDS4 standards. InSight is a geophysical lander with a science payload that includes a seismometer, a probe to measure subsurface temperatures and heat flow, a suite of meteorology instruments, a magnetometer, an experiment using radio tracking, and a robotic arm that will provide soil physical property information based on interactions with the surface. InSight is not the first science mission to archive its data using PDS4. However, PDS4 archives do not currently contain examples of the kinds of data that several of the InSight instruments will produce. Whereas the existing common PDS4 standards were sufficient for most of archiving requirements of InSight, the data generated by a few instruments required development of several extensions to the PDS4 information model. For example, the seismometer will deliver a version of its data in SEED format, which is standard for the terrestrial seismology community. This format required the design of a new product type in the PDS4 information model. A local data dictionary has also been developed for InSight that contains attributes that are not part of the common PDS4 dictionary. The local dictionary provides metadata relevant to all InSight data sets, and attributes specific to several of the instruments. Additional classes and attributes were designed for the existing PDS4 geometry dictionary that will capture metadata for the lander position and orientation, along with camera models for stereo image processing. Much of the InSight archive planning and design work has been done by a Data Archiving Working Group (DAWG), which has members from the InSight project and the PDS. The group coordinates archive design, schedules and peer review of the archive documentation and test products. The InSight DAWG archiving effort for PDS is being led by the PDS Geosciences Node with several other nodes working one-on-one with instruments relevant to their disciplines. Once the InSight mission begins operations, the DAWG will continue to provide oversight on release of InSight data to PDS. Lessons learned from InSight archive work will also feed forward to planning the archives for the Mars 2020 rover.

Socio-Emotional Effects of the Transition from Sight to Blindness

ERIC Educational Resources Information Center

Thurston, Mhairi; Thurston, Allen; McLeod, John

2010-01-01

The research examined the socio-emotional impact of sight loss on a sample of 18 blind and partially sighted adults from the east coast of Scotland (average age 64). The impact of sight loss in four core areas (mood, self-concept, social connectedness and loss) was explored. Data were collected using the mental health and social functioning…

The Play Behavior and Play Materials of Blind and Sighted Infants and Preschoolers.

ERIC Educational Resources Information Center

Troster, H.; Brambring, M.

1994-01-01

Analysis of questionnaires completed by parents of 91 young blind children and 74 matched sighted children indicated that sighted children engaged in more complex levels of play at an earlier age; blind children interacted less frequently with other children than did sighted children; blind children preferred tactile-auditory games and toys; and…

27 CFR 53.61 - Imposition and rates of tax.

Code of Federal Regulations, 2012 CFR

2012-04-01

... set of sights (iron or optical), sight mount or set of sight mounts, a choke, a flash hider, a muzzle brake, a magazine, a set of sling swivels, and/or an attachable ramrod for muzzle loading firearms when... sights and mounts, recoil pads, slings, sling swivels, chokes, and flash hiders/muzzle brakes of a type...

Sight-Singing Pedagogy: A Content Analysis of Choral Methods Textbooks

ERIC Educational Resources Information Center

Floyd, Eva G.; Haning, Marshall A.

2015-01-01

The purpose of this study was to examine the sight-singing pedagogy content of choral methods textbooks, with the intent of determining what elements of sight-singing pedagogy are most commonly included in these resources. A content analysis was conducted to analyze information related to sight-singing pedagogy in 10 textbooks that are commonly…

Assessment of rockfall risk along roads

NASA Astrophysics Data System (ADS)

Budetta, P.

2004-03-01

This paper contains a method for the analysis of rockfall risk along roads and motorways. The method is derived from the Rockfall Hazard Rating System (RHRS) developed by Pierson et al. (1990) at the Oregon State Highway Division. The RHRS provides a rational way to make informed decisions on where and how to spend construction funds. Exponential scoring functions are used to represent the increases, respectively, in hazard and in vulnerability that are reflected in the nine categories forming the classification. The resulting total score contains the essential elements regarding the evaluation of the degree of the exposition to the risk along roads. In the modified method, the ratings for the categories "ditch effectiveness", "geologic characteristic", "volume of rockfall/block size", "climate and water circulation" and "rockfall history" have been rendered more easy and objective. The main modifications regard the introduction of Slope Mass Rating by Romana (1985, 1988, 1991) improving the estimate of the geologic characteristics, of the volume of the potentially unstable blocks and the underground water circulation. Other modifications regard the scoring for the categories "decision sight distance" and "road geometry". For these categories, the Italian National Council's standards (Consiglio Nazionale delle Ricerche - CNR) have been used (CNR, 1980). The method must be applied in both the traffic directions because the percentage of reduction in the decision sight distance greatly affects the results. An application of the modified method to a 2km long section of the Sorrentine road (no 145) in Southern Italy was developed. A high traffic intensity affects the entire section of the road and rockfalls periodically cause casualties, as well as a large amount of damage and traffic interruptions. The method was applied to seven cross sections of slopes adjacent to the Sorrentine road. For these slopes, the analysis shows that the risk is unacceptable and it should be reduced using urgent remedial works.

A Method to Determine Angular Orientation of a Projectile Using a Polarization Scanning Reference Source

NASA Astrophysics Data System (ADS)

Kankipati, Venkata Varun

This thesis presents a method to determine the angular orientation of a projectile in flight, by mechanically scanning a linearly polarized, microwave reference source. In particular, the research focuses on real time measurement of the roll angle. A 10 GHz, linearly polarized electromagnetic wave is radiated toward the projectile by means of a 10 dB horn antenna. The projectile is equipped with a backward facing 10 dB horn antenna, which has orientation, namely roll angle, sensitivity. The response of the received signal follows a cosine law, producing a maximum when the receiver orientation is aligned with the transmitting polarization. As expected, the peak response shifts in response to the roll-angle, however, unambiguous recovery of the angle requires synchronization with the polarization orientation of the source. This has been achieved through the use of a unique transmitter power sequence, which includes a start-of-scan and end-of-scan time stamp. Based on the above concept, a complete system comprising a polarization scanning reference source, the receiving antenna mounted on a vehicle, and pertinent electronic components, has been tested for both line of sight and non-line of sight applications. The transmitter antenna, mounted on a computer controlled stepper motor allowed source polarization to be scanned from -90° to 90° in 0.3 seconds. The receiving antenna continuously samples the received electromagnetic background at the source frequency and uses a RF detector and a data acquisition system to record the subsequent time-varying voltage signal, which is processed to recover the roll-angle. Measurements in an anechoic chamber were used to confirm the efficacy of the system and field trials, using a transmitter power of 2 W, were successfully demonstrated over a distance of 0.15 miles. The distance limit can be extended by increasing the transmitter power, receiver sensitivity and increase source frequency.

Bats Avoid Radar Installations: Could Electromagnetic Fields Deter Bats from Colliding with Wind Turbines?

PubMed Central

Nicholls, Barry; Racey, Paul A.

2007-01-01

Large numbers of bats are killed by collisions with wind turbines, and there is at present no direct method of reducing or preventing this mortality. We therefore determine whether the electromagnetic radiation associated with radar installations can elicit an aversive behavioural response in foraging bats. Four civil air traffic control (ATC) radar stations, three military ATC radars and three weather radars were selected, each surrounded by heterogeneous habitat. Three sampling points matched for habitat type and structure, dominant vegetation species, altitude and surrounding land class were located at increasing distances from each station. A portable electromagnetic field meter measured the field strength of the radar at three distances from the source: in close proximity (<200 m) with a high electromagnetic field (EMF) strength >2 volts/metre, an intermediate point within line of sight of the radar (200–400 m) and with an EMF strength <2 v/m, and a control site out of sight of the radar (>400 m) and registering an EMF of zero v/m. At each radar station bat activity was recorded three times with three independent sampling points monitored on each occasion, resulting in a total of 90 samples, 30 of which were obtained within each field strength category. At these sampling points, bat activity was recorded using an automatic bat recording station, operated from sunset to sunrise. Bat activity was significantly reduced in habitats exposed to an EMF strength of greater than 2 v/m when compared to matched sites registering EMF levels of zero. The reduction in bat activity was not significantly different at lower levels of EMF strength within 400 m of the radar. We predict that the reduction in bat activity within habitats exposed to electromagnetic radiation may be a result of thermal induction and an increased risk of hyperthermia. PMID:17372629

First X-ray Statistical Tests for Clumpy-Torus Models: Constraints from RXTEmonitoring of Seyfert AGN

NASA Astrophysics Data System (ADS)

Markowitz, Alex; Krumpe, Mirko; Nikutta, R.

2016-06-01

In two papers (Markowitz, Krumpe, & Nikutta 2014, and Nikutta et al., in prep.), we derive the first X-ray statistical constraints for clumpy-torus models in Seyfert AGN by quantifying multi-timescale variability in line of-sight X-ray absorbing gas as a function of optical classification.We systematically search for discrete absorption events in the vast archive of RXTE monitoring of 55 nearby type Is and Compton-thin type IIs. We are sensitive to discrete absorption events due to clouds of full-covering, neutral/mildly ionized gas transiting the line of sight. Our results apply to both dusty and non-dusty clumpy media, and probe model parameter space complementary to that for eclipses observed with XMM-Newton, Suzaku, and Chandra.We detect twelve eclipse events in eight Seyferts, roughly tripling the number previously published from this archive. Event durations span hours to years. Most of our detected clouds are Compton-thin, and most clouds' distances from the black hole are inferred to be commensurate with the outer portions of the BLR or the inner regions of infrared-emitting dusty tori.We present the density profiles of the highest-quality eclipse events; the column density profile for an eclipsing cloud in NGC 3783 is doubly spiked, possibly indicating a cloud that is being tidallysheared. We discuss implications for cloud distributions in the context of clumpy-torus models. We calculate eclipse probabilities for orientation-dependent Type I/II unification schemes.We present constraints on cloud sizes, stability, and radial distribution. We infer that clouds' small angular sizes as seen from the SMBH imply 107 clouds required across the BLR + torus. Cloud size is roughly proportional to distance from the black hole, hinting at the formation processes (e.g., disk fragmentation). All observed clouds are sub-critical with respect to tidal disruption; self-gravity alone cannot contain them. External forces, such as magnetic fields or ambient pressure, are needed to contain them; otherwise, clouds must be short-lived.

The Three-dimensional Structure of the Small Magellanic Cloud

NASA Astrophysics Data System (ADS)

Subramanian, Smitha; Subramaniam, Annapurni

2012-01-01

The three-dimensional structure of the inner Small Magellanic Cloud (SMC) is investigated using the red clump (RC) stars and the RR Lyrae stars (RRLS), which represent the intermediate-age and the old stellar populations of a galaxy. The V- and I-band photometric data from the OGLE III catalog are used for our study. The mean dereddened I 0 magnitude of the RC stars and the RRLS are used to study the relative positions of the different regions in the SMC with respect to the mean SMC distance. This shows that the northeastern part of the SMC is closer to us. The line-of-sight depth (front to back distance) across the SMC is estimated using the dispersion in the I 0 magnitudes of both the RC stars and the RRLS and found to be large (~14 kpc) for both populations. The similarity in their depth distribution suggests that both of these populations occupy a similar volume of the SMC. The surface density distribution and the radial density profile of the RC stars suggest that they are more likely to be distributed in a nearly spheroidal system. The tidal radius estimated for the SMC system is ~7-12 kpc. An elongation along the NE-SW direction is seen in the surface density map of the RC stars. The surface density distribution of the RRLS in the SMC is nearly circular. Based on all of the above results the observed structure of the SMC, in which both the RC stars and RRLS are distributed, is approximated as a triaxial ellipsoid. The parameters of the ellipsoid are obtained using the inertia tensor analysis. We estimated the axes ratio, inclination of the longest axis with the line of sight (i), and the position angle (phi) of the longest axis of the ellipsoid on the sky from the analysis of the RRLS. The analysis of the RC stars with the assumption that they are extended up to a depth of 3.5 times the sigma (width of dereddened I 0 magnitude distribution, corrected for intrinsic spread and observational errors) was also found to give similar axes ratio and orientation angles. The above estimated parameters depend on the data coverage of the SMC. Using the RRLS with equal coverage in all three axes (data within 3° in X-, Y-, and Z-axes), we estimated an axes ratio of 1:1.33:1.61 with i = 2fdg6 and phi = 70fdg2. Our tidal radius estimates and the recent observational studies suggest that the full extent of the SMC in the XY plane is of the order of the front to back distance estimated along the line of sight. These results suggest that the structure of the SMC is spheroidal or slightly ellipsoidal. We propose that the SMC experienced a merger with another dwarf galaxy at ~4-5 Gyr ago, and the merger process was completed in another 2-3 Gyr. This resulted in a spheroidal distribution comprising stars older than 2 Gyr.

Results of observations of the dust distribution in the F-corona of the sun

NASA Astrophysics Data System (ADS)

Shestakova, L. I.; Demchenko, B. I.

2016-03-01

The results of modeling of the distribution of dust in the circumsolar zone are presented. The dust distribution was retrieved from observations of the line-of-sight velocities in the F-corona to the distances of 7-11 solar radii during the total eclipses of the Sun in different years: on July 31, 1981; August 11, 1991; March 29, 2006; and August 1, 2008. Comparison of the results has shown that the dust composition varies from year to year and the dust is dynamically nonuniform. In addition to the dust related to the zodiacal cloud and concentrating to the ecliptic plane, the dust of retrograde motion and the ejections and accretion in the polar regions are observed. From the results of observations of eclipses on July 31, 1981, August 11, 1991, and August 1, 2008, the east-west asymmetry in a sign of the line-of-sight velocities was detected: they are negative to the east of the Sun and positive to the west. Such distribution of the velocities is indicative of the nearecliptic orbital dust motion, whose direction coincides with that of the motion of the planets. In the course of the eclipse of March 29, 2006, almost no dynamical connection with the zodiacal cloud was found. At the same time, the direction, where the observed velocities are largest in value and opposite in sign on opposite sides of the Sun, was determined, which provides evidence of the orbital motion deviating from the ecliptic plane. The results of observations in 2006 reveal a clear genetic connection of the observed orbital motion of dust with the parent comets of the Kreutz family found near the Sun close to the eclipse date. The velocities observed near the symmetry line in the plane of the sky grow by absolute value with increasing the elongation, which may take place, if the line of sight croßses an empty zone that is free of dust. The modeling of the data of observations near the symmetry plane allowed the parameters of the dust distribution near the sublimation zone to be obtained. In 2006, the "black" cometary dust with a low albedo ( A = 0.05) was observed; it showed high values of the power-law exponents in the distance distribution of the dust concentration ( V = 2.2 > 1) and in the size distribution of grains (γ = 5.2 > 4.0) and a strong radiation pressure (β = 0.70-0.74). We estimated the mean radius of grains as ≈0.8-0.9 µm and the radius of the dust-free zone as ≈9.1-9.2 solar radii. The latter corresponds to the distances, where the low-melt components of olivines and pyroxenes disintegrate. In 2008, the observed zodiacal dust concentrating to the ecliptic plane demonstrated the canonical parameters: A = 0.1-0.2, V ≈ 1, ß ≈ 0, γ = 4.0, the mean radii of grains were 0.9-1.2 µm, and the radius of the dust-free zone was 7.0-7.6 solar radii.

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

Stu Spath, InSight program manager, Lockheed Martin Space, discusses NASA's InSight mission during a prelaunch media briefing, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

Tom Hoffman, InSight project manager, NASA JPL, right, discusses NASA's InSight mission during a prelaunch media briefing, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

Bruce Banerdt, InSight principal investigator, NASA JPL, discusses NASA's InSight mission during a prelaunch media briefing, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

The Development of a String Sight-Reading Pitch Skill Hierarchy

ERIC Educational Resources Information Center

Alexander, Michael L.; Henry, Michele L.

2012-01-01

This study was designed to determine a pitch skill hierarchy for string sight-reading, to determine the effects of key on string sight-reading achievement, and to determine the validity of a tonal pattern system as a measurement of melodic sight-reading skill for string players. High school string students (n = 94) obtained a mean score of 27.28…

An Investigation of Candidate Sensor-Observable Wake Vortex Strength Parameters for the NASA Aircraft Vortex Spacing System (AVOSS)

NASA Technical Reports Server (NTRS)

Tatnall, Chistopher R.

1998-01-01

The counter-rotating pair of wake vortices shed by flying aircraft can pose a threat to ensuing aircraft, particularly on landing approach. To allow adequate time for the vortices to disperse/decay, landing aircraft are required to maintain certain fixed separation distances. The Aircraft Vortex Spacing System (AVOSS), under development at NASA, is designed to prescribe safe aircraft landing approach separation distances appropriate to the ambient weather conditions. A key component of the AVOSS is a ground sensor, to ensure, safety by making wake observations to verify predicted behavior. This task requires knowledge of a flowfield strength metric which gauges the severity of disturbance an encountering aircraft could potentially experience. Several proposed strength metric concepts are defined and evaluated for various combinations of metric parameters and sensor line-of-sight elevation angles. Representative populations of generating and following aircraft types are selected, and their associated wake flowfields are modeled using various wake geometry definitions. Strength metric candidates are then rated and compared based on the correspondence of their computed values to associated aircraft response values, using basic statistical analyses.

An overview of applied visibility fundamentals: Survey and synthesis of a visibility literature

NASA Astrophysics Data System (ADS)

1982-06-01

The concept of visibility has been defined in numerous ways. One source that is widely used in the United States describes visibility as the greatest distance at which it is just possible to see and identify selected objects or light sources with the unaided eye, or, it may be considered the distance an observer would have to back away from a target before it disappears. The process by which we see distant objects is based on the characteristics of the target, its immediate surroundings, air quality, illumination of the sight path, and the eyes and brain of the observer. Thus, four components of visibility have been noted: (1) target, (2) background, (3) atmosphere, and (4) observer. Most definitions of visibility include the observer as a key element, but it is also possible to measure visibility without the immediate presence of humans by means of instruments such as telephotometers, transmissometers, or nephelometers. Such measurements can be kept in non-dimensional terms and can be compared without human intervention. When used in the field, however, visibility sensors must be calibrated in human terms of visibility measurement.

Problems in determining the surface density of the Galactic disk

NASA Technical Reports Server (NTRS)

Statler, Thomas S.

1989-01-01

A new method is presented for determining the local surface density of the Galactic disk from distance and velocity measurements of stars toward the Galactic poles. The procedure is fully three-dimensional, approximating the Galactic potential by a potential of Staeckel form and using the analytic third integral to treat the tilt and the change of shape of the velocity ellipsoid consistently. Applying the procedure to artificial data superficially resembling the K dwarf sample of Kuijken and Gilmore (1988, 1989), it is shown that the current best estimates of local disk surface density are uncertain by at least 30 percent. Of this, about 25 percent is due to the size of the velocity sample, about 15 percent comes from uncertainties in the rotation curve and the solar galactocentric distance, and about 10 percent from ignorance of the shape of the velocity distribution above z = 1 kpc, the errors adding in quadrature. Increasing the sample size by a factor of 3 will reduce the error to 20 percent. To achieve 10 percent accuracy, observations will be needed along other lines of sight to constrain the shape of the velocity ellipsoid.

Novae as distance indicators

NASA Technical Reports Server (NTRS)

Ford, Holland C.; Ciardullo, Robin

1988-01-01

Nova shells are characteristically prolate with equatorial bands and polar caps. Failure to account for the geometry can lead to large errors in expansion parallaxes for individual novae. When simple prescriptions are used for deriving expansion parallaxes from an ensemble of randomly oriented prolate spheroids, the average distance will be too small by factors of 10 to 15 percent. The absolute magnitudes of the novae will be underestimated and the resulting distance scale will be too small by the same factors. If observations of partially resolved nova shells select for large inclinations, the systematic error in the resulting distance scale could easily be 20 to 30 percent. Extinction by dust in the bulge of M31 may broaden and shift the intrinsic distribution of maximum nova magnitudes versus decay rates. We investigated this possibility by projecting Arp's and Rosino's novae onto a composite B - 6200A color map of M31's bulge. Thirty two of the 86 novae projected onto a smooth background with no underlying structure due to the presence of a dust cloud along the line of sight. The distribution of maximum magnitudes versus fade rates for these unreddened novae is indistinguishable from the distribution for the entire set of novae. It is concluded that novae suffer very little extinction from the filamentary and patchy distribution of dust seen in the bulge of M31. Time average B and H alpha nova luminosity functions are potentially powerful new ways to use novae as standard candles. Modern CCD observations and the photographic light curves of M31 novae found during the last 60 years were analyzed to show that these functions are power laws. Consequently, unless the eruption times for novae are known, the data cannot be used to obtain distances.

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

Social media guest listen as Bruce Banerdt, InSight principal investigator, NASA JPL, discusses NASA's InSight mission during a prelaunch media briefing, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

Examining the Validity of Self-Report: Middle-Level Singers' Ability to Predict and Assess Their Sight-Singing Skills

ERIC Educational Resources Information Center

Darrow, Alice-Ann; Marsh, Kerry

2006-01-01

The purpose of the present study was to determine choral students' ability to predict and evaluate their sight-singing skills. Participants were asked to assign a rating based on how well they predicted they would sight-sing five musical examples. Following the singing of each example, participants were asked to evaluate their sight-singing…

OBSERVATIONAL PROPERTIES OF ROTATIONALLY EXCITED MOLECULAR HYDROGEN IN TRANSLUCENT LINES OF SIGHT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jensen, Adam G.; Sonneborn, George; Snow, Theodore P.

2010-03-10

The Far Ultraviolet Spectroscopic Explorer (FUSE) has allowed precise determinations of the column densities of molecular hydrogen (H{sub 2}) in Galactic lines of sight with a wide range of pathlengths and extinction properties. However, survey studies of lines of sight with greater extinction have been mostly restricted to the low-J states (lower total angular momentum) in which most molecular hydrogen is observed. This paper presents a survey of column densities for the molecular hydrogen in states of greater rotational excitation (J >= 2) in Galactic lines of sight with log N(H{sub 2}) {approx}> 20. This study is comprehensive through themore » highest excited state detectable in each line of sight. J = 5 is observed in every line of sight, and we detect J = 7 in four lines of sight, J = 8 in one line of sight, and vibrationally excited H{sub 2} in two lines of sight. We compared the apparent b-values and velocity offsets of the higher-J states relative to the dominant low-J states and we found no evidence of any trends that might provide insight into the formation of higher-J H{sub 2}, although these results are the most affected by the limits of the FUSE resolution. We also derive excitation temperatures based on the column densities of the different states. We confirm that at least two distinct temperatures are necessary to adequately describe these lines of sight, and that more temperatures are probably necessary. Total H{sub 2} column density is known to be correlated with other molecules; we explore if correlations vary as a function of J for several molecules, most importantly CH and CH{sup +}. Finally, we briefly discuss interpretations of selected lines of sight by comparing them to models computed using the Meudon PDR code.« less

Identifying sighting clusters of endangered taxa with historical records.

PubMed

Duffy, Karl J

2011-04-01

The probability and time of extinction of taxa is often inferred from statistical analyses of historical records. Many of these analyses require the exclusion of multiple records within a unit of time (i.e., a month or a year). Nevertheless, spatially explicit, temporally aggregated data may be useful for identifying clusters of sightings (i.e., sighting clusters) in space and time. Identification of sighting clusters highlights changes in the historical recording of endangered taxa. I used two methods to identify sighting clusters in historical records: the Ederer-Myers-Mantel (EMM) test and the space-time permutation scan (STPS). I applied these methods to the spatially explicit sighting records of three species of orchids that are listed as endangered in the Republic of Ireland under the Wildlife Act (1976): Cephalanthera longifolia, Hammarbya paludosa, and Pseudorchis albida. Results with the EMM test were strongly affected by the choice of the time interval, and thus the number of temporal samples, used to examine the records. For example, sightings of P. albida clustered when the records were partitioned into 20-year temporal samples, but not when they were partitioned into 22-year temporal samples. Because the statistical power of EMM was low, it will not be useful when data are sparse. Nevertheless, the STPS identified regions that contained sighting clusters because it uses a flexible scanning window (defined by cylinders of varying size that move over the study area and evaluate the likelihood of clustering) to detect them, and it identified regions with high and regions with low rates of orchid sightings. The STPS analyses can be used to detect sighting clusters of endangered species that may be related to regions of extirpation and may assist in the categorization of threat status. ©2010 Society for Conservation Biology.

Typewriting: The Sight Method of Teaching Typewriting

ERIC Educational Resources Information Center

Ruddle, Eleanor S.

1970-01-01

Research with beginning typewriting students supports the use of the sight method-looking at the fingers and keyboard during the initial learning stages. The sight method increases the rate and degree of accuracy. (CH)

InSight Probes the 'Inner Space' of Mars

NASA Image and Video Library

2018-01-25

An artist's impression of the InSight lander on Mars. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is designed to give the Red Planet its first thorough check up since it formed 4.5 billion years ago. It is scheduled to launch from Vandenberg Air Force Base on the California coast between May 5 through June 8, 2018, and land on Mars six months later. InSight will look for tectonic activity and meteorite impacts, study how much heat is still flowing through the planet, and track Mars' wobble as it orbits the sun. While InSight is a Mars mission, it's more than a Mars mission. InSight will help answer key questions about the formation of the rocky planets of the solar system. https://photojournal.jpl.nasa.gov/catalog/PIA22226

Delineating and identifying long-term changes in the whooping crane (Grus americana) migration corridor.

PubMed

Pearse, Aaron T; Rabbe, Matt; Juliusson, Lara M; Bidwell, Mark T; Craig-Moore, Lea; Brandt, David A; Harrell, Wade

2018-01-01

Defining and identifying changes to seasonal ranges of migratory species is required for effective conservation. Historic sightings of migrating whooping cranes (Grus americana) have served as sole source of information to define a migration corridor in the Great Plains of North America (i.e., Canadian Prairies and United States Great Plains) for this endangered species. We updated this effort using past opportunistic sightings from 1942-2016 (n = 5,055) and more recent (2010-2016) location data from 58 telemetered birds (n = 4,423) to delineate migration corridors that included 50%, 75%, and 95% core areas. All migration corridors were well defined and relatively compact, with the 95% core corridor averaging 294 km wide, although it varied approximately ±40% in width from 170 km in central Texas to 407 km at the international border of the United States and Canada. Based on historic sightings and telemetry locations, we detected easterly movements in locations over time, primarily due to locations west of the median shifting east. This shift occurred from northern Oklahoma to central Saskatchewan at an average rate of 1.2 km/year (0.3-2.8 km/year). Associated with this directional shift was a decrease in distance of locations from the median in the same region averaging -0.7 km/year (-0.3--1.3 km/year), suggesting a modest narrowing of the migration corridor. Changes in the corridor over the past 8 decades suggest that agencies and organizations interested in recovery of this species may need to modify where conservation and recovery actions occur. Whooping cranes showed apparent plasticity in their migratory behavior, which likely has been necessary for persistence of a wetland-dependent species migrating through the drought-prone Great Plains. Behavioral flexibility will be useful for whooping cranes to continue recovery in a future of uncertain climate and land use changes throughout their annual range.

Delineating and identifying long-term changes in the whooping crane (Grus americana) migration corridor

PubMed Central

Rabbe, Matt; Juliusson, Lara M.; Bidwell, Mark T.; Craig-Moore, Lea; Brandt, David A.; Harrell, Wade

2018-01-01

Defining and identifying changes to seasonal ranges of migratory species is required for effective conservation. Historic sightings of migrating whooping cranes (Grus americana) have served as sole source of information to define a migration corridor in the Great Plains of North America (i.e., Canadian Prairies and United States Great Plains) for this endangered species. We updated this effort using past opportunistic sightings from 1942–2016 (n = 5,055) and more recent (2010–2016) location data from 58 telemetered birds (n = 4,423) to delineate migration corridors that included 50%, 75%, and 95% core areas. All migration corridors were well defined and relatively compact, with the 95% core corridor averaging 294 km wide, although it varied approximately ±40% in width from 170 km in central Texas to 407 km at the international border of the United States and Canada. Based on historic sightings and telemetry locations, we detected easterly movements in locations over time, primarily due to locations west of the median shifting east. This shift occurred from northern Oklahoma to central Saskatchewan at an average rate of 1.2 km/year (0.3–2.8 km/year). Associated with this directional shift was a decrease in distance of locations from the median in the same region averaging -0.7 km/year (-0.3–-1.3 km/year), suggesting a modest narrowing of the migration corridor. Changes in the corridor over the past 8 decades suggest that agencies and organizations interested in recovery of this species may need to modify where conservation and recovery actions occur. Whooping cranes showed apparent plasticity in their migratory behavior, which likely has been necessary for persistence of a wetland-dependent species migrating through the drought-prone Great Plains. Behavioral flexibility will be useful for whooping cranes to continue recovery in a future of uncertain climate and land use changes throughout their annual range. PMID:29447213

Delineating and identifying long-term changes in the whooping crane (Grus americana) migration corridor

USGS Publications Warehouse

Pearse, Aaron T.; Rabbe, Matt; Juliusson, Lara M.; Bidwell, Mark T.; Craig-Moore, Lea; Brandt, David; Harrell, Wade C.

2018-01-01

Defining and identifying changes to seasonal ranges of migratory species is required for effective conservation. Historic sightings of migrating whooping cranes (Grus americana) have served as sole source of information to define a migration corridor in the Great Plains of North America (i.e., Canadian Prairies and United States Great Plains) for this endangered species. We updated this effort using past opportunistic sightings from 1942–2016 (n = 5,055) and more recent (2010–2016) location data from 58 telemetered birds (n = 4,423) to delineate migration corridors that included 50%, 75%, and 95% core areas. All migration corridors were well defined and relatively compact, with the 95% core corridor averaging 294 km wide, although it varied approximately ±40% in width from 170 km in central Texas to 407 km at the international border of the United States and Canada. Based on historic sightings and telemetry locations, we detected easterly movements in locations over time, primarily due to locations west of the median shifting east. This shift occurred from northern Oklahoma to central Saskatchewan at an average rate of 1.2 km/year (0.3–2.8 km/year). Associated with this directional shift was a decrease in distance of locations from the median in the same region averaging -0.7 km/year (-0.3–-1.3 km/year), suggesting a modest narrowing of the migration corridor. Changes in the corridor over the past 8 decades suggest that agencies and organizations interested in recovery of this species may need to modify where conservation and recovery actions occur. Whooping cranes showed apparent plasticity in their migratory behavior, which likely has been necessary for persistence of a wetland-dependent species migrating through the drought-prone Great Plains. Behavioral flexibility will be useful for whooping cranes to continue recovery in a future of uncertain climate and land use changes throughout their annual range.

A variable-density absorption event in NGC 3227 mapped with Suzaku and Swift

NASA Astrophysics Data System (ADS)

Beuchert, T.; Markowitz, A. G.; Krauß, F.; Miniutti, G.; Longinotti, A. L.; Guainazzi, M.; de La Calle Pérez, I.; Malkan, M.; Elvis, M.; Miyaji, T.; Hiriart, D.; López, J. M.; Agudo, I.; Dauser, T.; Garcia, J.; Kreikenbohm, A.; Kadler, M.; Wilms, J.

2015-12-01

Context. The morphology of the circumnuclear gas accreting onto supermassive black holes in Seyfert galaxies remains a topic of much debate. As the innermost regions of active galactic nuclei (AGN) are spatially unresolved, X-ray spectroscopy, and in particular line-of-sight absorption variability, is a key diagnostic to map out the distribution of gas. Aims: Observations of variable X-ray absorption in multiple Seyferts and over a wide range of timescales indicate the presence of clumps/clouds of gas within the circumnuclear material. Eclipse events by clumps transiting the line of sight allow us to explore the properties of the clumps over a wide range of radial distances from the optical/UV broad line region (BLR) to beyond the dust sublimation radius. Time-resolved absorption events have been extremely rare so far, but suggest a range of density profiles across Seyferts. We resolve a weeks-long absorption event in the Seyfert NGC 3227. Methods: We examine six Suzaku and 12 Swift observations from a 2008 campaign spanning five weeks. We use a model accounting for the complex spectral interplay of three absorbers with different levels of ionization. We perform time-resolved spectroscopy to discern the absorption variability behavior. We also examine the IR to X-ray spectral energy distribution (SED) to test for reddening by dust. Results: The 2008 absorption event is due to moderately-ionized (log ξ ~ 1.2-1.4) gas covering 90% of the line of sight. We resolve the density profile to be highly irregular, in contrast to a previous symmetric and centrally-peaked event mapped with RXTE in the same object. The UV data do not show significant reddening, suggesting that the cloud is dust-free. Conclusions: The 2008 campaign has revealed a transit by a filamentary, moderately-ionized cloud of variable density that is likely located in the BLR, and possibly part of a disk wind.

Tactile Acuity in the Blind: A Closer Look Reveals Superiority over the Sighted in Some but Not All Cutaneous Tasks

ERIC Educational Resources Information Center

Alary, Flamine; Duquette, Marco; Goldstein, Rachel; Chapman, C. Elaine; Voss, Patrice; La Buissonniere-Ariza, Valerie; Lepore, Franco

2009-01-01

Previous studies have shown that blind subjects may outperform the sighted on certain tactile discrimination tasks. We recently showed that blind subjects outperformed the sighted in a haptic 2D-angle discrimination task. The purpose of this study was to compare the performance of the same blind (n = 16) and sighted (n = 17, G1) subjects in three…

Factors influencing load-haul-dump operator line of sight in underground mining.

PubMed

Eger, Tammy; Salmoni, Alan; Whissell, Robert

2004-03-01

The inability of load-haul-dump (LHD) equipment operators to see people, objects or hazards around the LHD machine they drive is a causal factor in a number of serious accidents. Line of sight evaluations were conducted on 11 different LHD models. Results indicated blind spots were caused by cab posts, and vehicles lights and light brackets. Line of sight impairments were caused by wheel well covers, buckets, fire extinguisher, light posts, radiator covers, booms, radio remote boxes, elevated engine profiles and air intake cylinders. These results were supported by questionnaires completed by 130 LHD operators. The operators indicated the bucket, lights and light brackets, boom and cab impaired line of sight. Line of sight testing and LHD operator feedback indicated line of sight to the right front corner and back right corner were typically worse than line of sight to the front left side of the vehicle. Results of this study have been used to conduct awareness campaigns within the Ontario mining industry and to suggest vehicle design modifications to LHD manufacturers.

Toward Measuring Galactic Dense Molecular Gas Properties and 3D Distribution with Hi-GAL

NASA Astrophysics Data System (ADS)

Zetterlund, Erika; Glenn, Jason; Maloney, Phil

2016-01-01

The Herschel Space Observatory's submillimeter dust continuum survey Hi-GAL provides a powerful new dataset for characterizing the structure of the dense interstellar medium of the Milky Way. Hi-GAL observed a 2° wide strip covering the entire 360° of the Galactic plane in broad bands centered at 70, 160, 250, 350, and 500 μm, with angular resolution ranging from 10 to 40 arcseconds. We are adapting a molecular cloud clump-finding algorithm and a distance probability density function distance-determination method developed for the Bolocam Galactic Plane Survey (BGPS) to the Hi-GAL data. Using these methods we expect to generate a database of 105 cloud clumps, derive distance information for roughly half the clumps, and derive precise distances for approximately 20% of them. With five-color photometry and distances, we will measure the cloud clump properties, such as luminosities, physical sizes, and masses, and construct a three-dimensional map of the Milky Way's dense molecular gas distribution.The cloud clump properties and the dense gas distribution will provide critical ground truths for comparison to theoretical models of molecular cloud structure formation and galaxy evolution models that seek to emulate spiral galaxies. For example, such models cannot resolve star formation and use prescriptive recipes, such as converting a fixed fraction of interstellar gas to stars at a specified interstellar medium density threshold. The models should be compared to observed dense molecular gas properties and galactic distributions.As a pilot survey to refine the clump-finding and distance measurement algorithms developed for BGPS, we have identified molecular cloud clumps in six 2° × 2° patches of the Galactic plane, including one in the inner Galaxy along the line of sight through the Molecular Ring and the termination of the Galactic bar and one toward the outer Galaxy. Distances have been derived for the inner Galaxy clumps and compared to Bolocam Galactic Plane Survey results. We present the pilot survey clump catalog, distances, clump properties, and a comparison to BGPS.

NLOS Correction/Exclusion for GNSS Measurement Using RAIM and City Building Models

PubMed Central

Hsu, Li-Ta; Gu, Yanlei; Kamijo, Shunsuke

2015-01-01

Currently, global navigation satellite system (GNSS) receivers can provide accurate and reliable positioning service in open-field areas. However, their performance in the downtown areas of cities is still affected by the multipath and none-line-of-sight (NLOS) receptions. This paper proposes a new positioning method using 3D building models and the receiver autonomous integrity monitoring (RAIM) satellite selection method to achieve satisfactory positioning performance in urban area. The 3D building model uses a ray-tracing technique to simulate the line-of-sight (LOS) and NLOS signal travel distance, which is well-known as pseudorange, between the satellite and receiver. The proposed RAIM fault detection and exclusion (FDE) is able to compare the similarity between the raw pseudorange measurement and the simulated pseudorange. The measurement of the satellite will be excluded if the simulated and raw pseudoranges are inconsistent. Because of the assumption of the single reflection in the ray-tracing technique, an inconsistent case indicates it is a double or multiple reflected NLOS signal. According to the experimental results, the RAIM satellite selection technique can reduce by about 8.4% and 36.2% the positioning solutions with large errors (solutions estimated on the wrong side of the road) for the 3D building model method in the middle and deep urban canyon environment, respectively. PMID:26193278

Congenital blindness limits allocentric to egocentric switching ability.

PubMed

Ruggiero, Gennaro; Ruotolo, Francesco; Iachini, Tina

2018-03-01

Many everyday spatial activities require the cooperation or switching between egocentric (subject-to-object) and allocentric (object-to-object) spatial representations. The literature on blind people has reported that the lack of vision (congenital blindness) may limit the capacity to represent allocentric spatial information. However, research has mainly focused on the selective involvement of egocentric or allocentric representations, not the switching between them. Here we investigated the effect of visual deprivation on the ability to switch between spatial frames of reference. To this aim, congenitally blind (long-term visual deprivation), blindfolded sighted (temporary visual deprivation) and sighted (full visual availability) participants were compared on the Ego-Allo switching task. This task assessed the capacity to verbally judge the relative distances between memorized stimuli in switching (from egocentric-to-allocentric: Ego-Allo; from allocentric-to-egocentric: Allo-Ego) and non-switching (only-egocentric: Ego-Ego; only-allocentric: Allo-Allo) conditions. Results showed a difficulty in congenitally blind participants when switching from allocentric to egocentric representations, not when the first anchor point was egocentric. In line with previous results, a deficit in processing allocentric representations in non-switching conditions also emerged. These findings suggest that the allocentric deficit in congenital blindness may determine a difficulty in simultaneously maintaining and combining different spatial representations. This deficit alters the capacity to switch between reference frames specifically when the first anchor point is external and not body-centered.

Physically detached 'compact groups'

NASA Technical Reports Server (NTRS)

Hernquist, Lars; Katz, Neal; Weinberg, David H.

1995-01-01

A small fraction of galaxies appear to reside in dense compact groups, whose inferred crossing times are much shorter than a Hubble time. These short crossing times have led to considerable disagreement among researchers attempting to deduce the dynamical state of these systems. In this paper, we suggest that many of the observed groups are not physically bound but are chance projections of galaxies well separated along the line of sight. Unlike earlier similar proposals, ours does not require that the galaxies in the compact group be members of a more diffuse, but physically bound entity. The probability of physically separated galaxies projecting into an apparent compact group is nonnegligible if most galaxies are distributed in thin filaments. We illustrate this general point with a specific example: a simulation of a cold dark matter universe, in which hydrodynamic effects are included to identify galaxies. The simulated galaxy distribution is filamentary and end-on views of these filaments produce apparent galaxy associations that have sizes and velocity dispersions similar to those of observed compact groups. The frequency of such projections is sufficient, in principle, to explain the observed space density of groups in the Hickson catalog. We discuss the implications of our proposal for the formation and evolution of groups and elliptical galaxies. The proposal can be tested by using redshift-independent distance estimators to measure the line-of-sight spatial extent of nearby compact groups.

PDR MODEL MAPPING OF OBSCURED H{sub 2} EMISSION AND THE LINE-OF-SIGHT STRUCTURE OF M17-SW

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheffer, Y.; Wolfire, M. G.

2013-09-01

We observed H{sub 2} line emission with Spitzer-IRS toward M17-SW and modeled the data with our photon-dominated region (PDR) code. Derived gas density values of up to few times 10{sup 7} cm{sup -3} indicate that H{sub 2} emission originates in high-density clumps. We discover that the PDR code can be utilized to map the amount of intervening extinction obscuring the H{sub 2} emission layers, and thus we obtain the radial profile of A{sub V} relative to the central ionizing cluster NGC 6618. The extinction has a positive radial gradient, varying between 15-47 mag over the projected distance of 0.9-2.5 pcmore » from the primary ionizer, CEN 1. These high extinction values are in good agreement with previous studies of A{sub V} toward stellar targets in M17-SW. The ratio of data to PDR model values is used to infer the global line-of-sight structure of the PDR surface, which is revealed to resemble a concave surface relative to NGC 6618. Such a configuration confirms that this PDR can be described as a bowl-shaped boundary of the central H II region in M17. The derived structure and physical conditions are important for interpreting the fine-structure and rotational line emission from the PDR.« less

Small-Scale, Local Area, and Transitional Millimeter Wave Propagation for 5G Communications

NASA Astrophysics Data System (ADS)

Rappaport, Theodore S.; MacCartney, George R.; Sun, Shu; Yan, Hangsong; Deng, Sijia

2017-12-01

This paper studies radio propagation mechanisms that impact handoffs, air interface design, beam steering, and MIMO for 5G mobile communication systems. Knife edge diffraction (KED) and a creeping wave linear model are shown to predict diffraction loss around typical building objects from 10 to 26 GHz, and human blockage measurements at 73 GHz are shown to fit a double knife-edge diffraction (DKED) model which incorporates antenna gains. Small-scale spatial fading of millimeter wave received signal voltage amplitude is generally Ricean-distributed for both omnidirectional and directional receive antenna patterns under both line-of-sight (LOS) and non-line-of-sight (NLOS) conditions in most cases, although the log-normal distribution fits measured data better for the omnidirectional receive antenna pattern in the NLOS environment. Small-scale spatial autocorrelations of received voltage amplitudes are shown to fit sinusoidal exponential and exponential functions for LOS and NLOS environments, respectively, with small decorrelation distances of 0.27 cm to 13.6 cm (smaller than the size of a handset) that are favorable for spatial multiplexing. Local area measurements using cluster and route scenarios show how the received signal changes as the mobile moves and transitions from LOS to NLOS locations, with reasonably stationary signal levels within clusters. Wideband mmWave power levels are shown to fade from 0.4 dB/ms to 40 dB/s, depending on travel speed and surroundings.

AN OCCULTATION EVENT IN CENTAURUS A AND THE CLUMPY TORUS MODEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rivers, Elizabeth; Markowitz, Alex; Rothschild, Richard, E-mail: erivers@ucsd.edu

2011-12-15

We have analyzed 16 months of sustained monitoring observations of Centaurus A from the Rossi X-Ray Timing Explorer to search for changes in the absorbing column in the line of sight to the central nucleus. We present time-resolved spectroscopy which indicates that a discrete clump of material transited the line of sight to the central illuminating source over the course of {approx}170 days between 2010 August and 2011 February with a maximum increase in the column density of about 8.4 Multiplication-Sign 10{sup 22} cm{sup -2}. This is the best quality data of such an event that has ever been analyzedmore » with the shape of the ingress and egress clearly seen. Modeling the clump of material as roughly spherical with a linearly decreasing density profile and assuming a distance from the central nucleus commensurate with the dusty torus, we found that the clump would have a diameter of (1.4-2.4) Multiplication-Sign 10{sup 15} cm with a central number density of n{sub H} = (1.8-3.0) Multiplication-Sign 10{sup 7} cm{sup -3}. This is consistent with previous results for a similar (though possibly much longer) occultation event inferred in this source in 2003-2004 and supports models of the molecular torus as a clumpy medium.« less

Developing a Sight Conservation Program

ERIC Educational Resources Information Center

Braxton, Olivia A.; Farris, R. Linsy

1975-01-01

Among the services added to Harlem (New York) Hospital's opthalmology department was a sight conservation program designed to alert the community to the need for eye care and to screen for early signs of eye disorders causing sight impairment. (SB)

An Exploration into Self Concept: A Comparative Analysis between the Adolescents Who Are Sighted and Blind in India

ERIC Educational Resources Information Center

Halder, Santoshi; Datta, Poulomee

2012-01-01

The purpose of this study was to explore the self concept of adolescents who are sighted and blind with respect to gender in India. The sample was made up of 160 participants aged 15 to 18 years: of whom 100 were sighted and 60 were blind. The results of the t-tests illustrated that sighted male adolescents scored higher in the overall…

Line-of-sight structure toward strong lensing galaxy clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bayliss, Matthew B.; Johnson, Traci; Sharon, Keren

2014-03-01

We present an analysis of the line-of-sight structure toward a sample of 10 strong lensing cluster cores. Structure is traced by groups that are identified spectroscopically in the redshift range, 0.1 ≤ z ≤ 0.9, and we measure the projected angular and comoving separations between each group and the primary strong lensing clusters in each corresponding line of sight. From these data we measure the distribution of projected angular separations between the primary strong lensing clusters and uncorrelated large-scale structure as traced by groups. We then compare the observed distribution of angular separations for our strong lensing selected lines ofmore » sight against the distribution of groups that is predicted for clusters lying along random lines of sight. There is clear evidence for an excess of structure along the line of sight at small angular separations (θ ≤ 6') along the strong lensing selected lines of sight, indicating that uncorrelated structure is a significant systematic that contributes to producing galaxy clusters with large cross sections for strong lensing. The prevalence of line-of-sight structure is one of several biases in strong lensing clusters that can potentially be folded into cosmological measurements using galaxy cluster samples. These results also have implications for current and future studies—such as the Hubble Space Telescope Frontier Fields—that make use of massive galaxy cluster lenses as precision cosmological telescopes; it is essential that the contribution of line-of-sight structure be carefully accounted for in the strong lens modeling of the cluster lenses.« less

Identification and detection of simple 3D objects with severely blurred vision.

PubMed

Kallie, Christopher S; Legge, Gordon E; Yu, Deyue

2012-12-05

Detecting and recognizing three-dimensional (3D) objects is an important component of the visual accessibility of public spaces for people with impaired vision. The present study investigated the impact of environmental factors and object properties on the recognition of objects by subjects who viewed physical objects with severely reduced acuity. The experiment was conducted in an indoor testing space. We examined detection and identification of simple convex objects by normally sighted subjects wearing diffusing goggles that reduced effective acuity to 20/900. We used psychophysical methods to examine the effect on performance of important environmental variables: viewing distance (from 10-24 feet, or 3.05-7.32 m) and illumination (overhead fluorescent and artificial window), and object variables: shape (boxes and cylinders), size (heights from 2-6 feet, or 0.61-1.83 m), and color (gray and white). Object identification was significantly affected by distance, color, height, and shape, as well as interactions between illumination, color, and shape. A stepwise regression analysis showed that 64% of the variability in identification could be explained by object contrast values (58%) and object visual angle (6%). When acuity is severely limited, illumination, distance, color, height, and shape influence the identification and detection of simple 3D objects. These effects can be explained in large part by the impact of these variables on object contrast and visual angle. Basic design principles for improving object visibility are discussed.

Packed Planetary Systems

NASA Astrophysics Data System (ADS)

Barnes, R.; Greenberg, R.

2005-08-01

Planetary systems display a wide range of appearances, with apparently arbitrary values of semi-major axis, eccentricity, etc. We reduce the complexity of orbital configurations to a single value, δ , which is a measure of how close, over secular timescales ( ˜10,000 orbits), two consecutive planets come to each other. We measure this distance relative to the sum of the radii of their Hill spheres, sometimes referred to as mutual Hill radii (MHR). We determine the closest approach distance by numerically integrating the entire system on coplanar orbits, using minimum masses. For non-resonant systems, close approach occurs during apsidal alignment, either parallel or anti-parallel. For resonant pairs the distance at conjunction determines the closest approach distance. Previous analytic work found that planets on circular orbits were assuredly unstable if they came within 3.5 MHR (i.e. Gladman 1993; Chambers, Wetherill & Boss 1996). We find that most known pairs of jovian planets (including those in our solar system) come within 3.5 -- 7 MHR of each other. We also find that several systems are unstable (their closest approach distance is less than 3.5 MHR). These systems, if they are real, probably exist in an observationally permitted location somewhat different from the current best fit. In these cases, the planets' closest approach distance will most likely also be slightly larger than 3.5 MHR. Most pairs beyond 7 MHR probably experienced post-formation migration (i.e. tidal circularization, inward scattering of small bodies) which moved them further apart. This result is even more remarkable since we have used the minimum masses; most likely the systems are inclined to the line of sight, making the Hill spheres larger, and shrinking δ . This dense packing may reflect a tendency for planets to form as close together as they can without being dynamically unstable. This result further implies there may be a large number of smaller, currently undetectable companions packed in orbits around stars with known planets.

Effects of pile-driving on harbour porpoises (Phocoena phocoena) at the first offshore wind farm in Germany

NASA Astrophysics Data System (ADS)

Dähne, Michael; Gilles, Anita; Lucke, Klaus; Peschko, Verena; Adler, Sven; Krügel, Kathrin; Sundermeyer, Janne; Siebert, Ursula

2013-06-01

The first offshore wind farm ‘alpha ventus’ in the German North Sea was constructed north east of Borkum Reef Ground approximately 45 km north off the German coast in 2008 and 2009 using percussive piling for the foundations of 12 wind turbines. Visual monitoring of harbour porpoises was conducted prior to as well as during construction and operation by means of 15 aerial line transect distance sampling surveys, from 2008 to 2010. Static acoustic monitoring (SAM) with echolocation click loggers at 12 positions was performed additionally from 2008 to 2011. SAM devices were deployed between 1 and 50 km from the centre of the wind farm. During aerial surveys, 18 600 km of transect lines were covered in two survey areas (10 934 and 11 824 km2) and 1392 harbour porpoise sightings were recorded. Lowest densities were documented during the construction period in 2009. The spatial distribution pattern recorded on two aerial surveys three weeks before and exactly during pile-driving points towards a strong avoidance response within 20 km distance of the noise source. Generalized additive modelling of SAM data showed a negative impact of pile-driving on relative porpoise detection rates at eight positions at distances less than 10.8 km. Increased detection rates were found at two positions at 25 and 50 km distance suggesting that porpoises were displaced towards these positions. A pile-driving related behavioural reaction could thus be detected using SAM at a much larger distance than a pure avoidance radius would suggest. The first waiting time (interval between porpoise detections of at least 10 min), after piling started, increased with longer piling durations. A gradient in avoidance, a gradual fading of the avoidance reaction with increasing distance from the piling site, is hence most probably a product of an incomplete displacement during shorter piling events.

THE STAR FORMATION HISTORY AND EXTENDED STRUCTURE OF THE HERCULES MILKY WAY SATELLITE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sand, David J.; Seth, Anil; Olszewski, Edward W.

2009-10-20

We present imaging of the recently discovered Hercules Milky Way satellite and its surrounding regions to study its structure, star formation history and to thoroughly search for signs of disruption. We robustly determine the distance, luminosity, size, and morphology of Hercules utilizing a bootstrap approach to characterize our uncertainties. We derive a distance to Hercules via a comparison to empirical and theoretical isochrones, finding a best match with the isochrone of M92, which yields a distance of 133 +- 6 kpc. As previous studies have found, Hercules is very elongated, with epsilon = 0.67 +- 0.03 and a half-light radiusmore » of r{sub h} approx = 230 pc. Using the color-magnitude-fitting package StarFISH, we determine that Hercules is old (>12 Gyr) and metal-poor ([Fe/H] approx -2.0), with a spread in metallicity, in agreement with previous spectroscopic work. This result is robust with respect to slight variations in the distance to Hercules and mismatches between the observed Hercules color-magnitude diagram and theoretical isochrones. We infer a total absolute magnitude of M{sub V} = -6.2 +- 0.4. Our innovative search for external Hercules structure both in the plane of the sky and along the line of sight yields some evidence that Hercules is embedded in a larger stream of stars. A clear stellar extension is seen to the northwest with several additional candidate stellar overdensities along the position angle of Hercules out to approx35' (approx1.3 kpc). While the association of any of the individual stellar overdensities with Hercules is difficult to determine, we do show that the summed color-magnitude diagram of all three is consistent with Hercules' stellar population. Finally, we estimate that any change in the distance to Hercules across its face is at most approx6 kpc, and the data are consistent with Hercules being at the same distance throughout.« less

Random Forest population modelling of striped and common-bottlenose dolphins in the Gulf of Taranto (Northern Ionian Sea, Central-eastern Mediterranean Sea)

NASA Astrophysics Data System (ADS)

Carlucci, Roberto; Cipriano, Giulia; Paoli, Chiara; Ricci, Pasquale; Fanizza, Carmelo; Capezzuto, Francesca; Vassallo, Paolo

2018-05-01

This study provides the first estimates of density and abundance of the striped dolphin Stenella coeruleoalba and common bottlenose dolphin Tursiops truncatus in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea) and identifies the predictive variables mainly influencing their occurrence and concentration in the study area. Conventional Distance Sampling (CDS) and the Delta approach on Random Forest (DaRF) methods have been applied to sightings data collected between 2009 and 2016 during standardized vessel-based surveys, providing similar outcomes. The mean value of density over the entire study area was 0.72 ± 0.26 specimens/km2 for the striped dolphin and 0.47 ± 0.09 specimens/km2 for the common bottlenose dolphin. The abundance estimated by DaRF in the Gulf of Taranto was 10080 ± 3584 specimens of S. coeruleoalba and 6580 ± 1270 specimens of T. truncatus, respectively. Eight predictive variables were selected, considering both the local physiographic features and human activities existing in the investigated area. The explanatory variables depth, distance from the coast, distance from industrial areas and distance from areas exploited by fishery seem to play a key role in influencing the spatial distribution of both species, whereas the geomorphological variables proved to be the most significant factors shaping the concentration of both dolphins. The establishment of a Specially Protected Area of Mediterranean Importance (SPAMI) according the SPA/BD Protocol in the Gulf of Taranto is indicated as an effective management tool for the conservation of both dolphin populations in the Central-eastern Mediterranean Sea.

Is the Milky Way still breathing? RAVE-Gaia streaming motions

NASA Astrophysics Data System (ADS)

Carrillo, I.; Minchev, I.; Kordopatis, G.; Steinmetz, M.; Binney, J.; Anders, F.; Bienaymé, O.; Bland-Hawthorn, J.; Famaey, B.; Freeman, K. C.; Gilmore, G.; Gibson, B. K.; Grebel, E. K.; Helmi, A.; Just, A.; Kunder, A.; McMillan, P.; Monari, G.; Munari, U.; Navarro, J.; Parker, Q. A.; Reid, W.; Seabroke, G.; Sharma, S.; Siebert, A.; Watson, F.; Wojno, J.; Wyse, R. F. G.; Zwitter, T.

2018-04-01

We use data from the Radial Velocity Experiment (RAVE) and the Tycho-Gaia astrometric solution (TGAS) catalogue to compute the velocity fields yielded by the radial (VR), azimuthal (Vϕ),and vertical (Vz) components of associated Galactocentric velocity. We search in particular for variation in all three velocity components with distance above and below the disc mid-plane, as well as how each component of Vz (line-of-sight and tangential velocity projections) modifies the obtained vertical structure. To study the dependence of velocity on proper motion and distance, we use two main samples: a RAVE sample including proper motions from the Tycho-2, PPMXL, and UCAC4 catalogues, and a RAVE-TGAS sample with inferred distances and proper motions from the TGAS and UCAC5 catalogues. In both samples, we identify asymmetries in VR and Vz. Below the plane, we find the largest radial gradient to be ∂VR/∂R = -7.01 ± 0.61 km s-1 kpc-1, in agreement with recent studies. Above the plane, we find a similar gradient with ∂VR/∂R = -9.42 ± 1.77 km s-1 kpc-1. By comparing our results with previous studies, we find that the structure in Vz is strongly dependent on the adopted proper motions. Using the Galaxia Milky Way model, we demonstrate that distance uncertainties can create artificial wave-like patterns. In contrast to previous suggestions of a breathing mode seen in RAVE data, our results support a combination of bending and breathing modes, likely generated by a combination of external or internal and external mechanisms.

Discovery of a transparent sightline at ρ ≲ 20 kpc from an interacting pair of galaxies

NASA Astrophysics Data System (ADS)

Johnson, Sean D.; Chen, Hsiao-Wen; Mulchaey, John S.; Tripp, Todd M.; Prochaska, J. Xavier; Werk, Jessica K.

2014-03-01

We report the discovery of a transparent sightline at projected distances of ρ ≲ 20 kpc to an interacting pair of mature galaxies at z = 0.12. The sightline of the UV-bright quasar PG 1522+101 at zem = 1.328 passes at ρ = 11.5 kpc from the higher mass galaxy (M* = 1010.6 M⊙) and ρ = 20.4 kpc from the lower mass one (M* = 1010.0 M⊙). The two galaxies are separated by 9 kpc in projected distance and 30 km s-1 in line-of-sight velocity. Deep optical images reveal tidal features indicative of close interactions. Despite the small projected distances, the quasar sightline shows little absorption associated with the galaxy pair with a total H I column density no greater than log N({H I})/cm^{-2}=13.65. This limiting H I column density is already two orders of magnitude less than what is expected from previous halo gas studies. In addition, we detect no heavy-element absorption features associated with the galaxy pair with 3σ limits of log N({Mg II})/cm^{-2} < 12.2 and log N({O VI})/cm^{-2} < 13.7. The probability of seeing such little absorption in a sightline passing at a small projected distance from two non-interacting galaxies is 0.2 per cent. The absence of strong absorbers near the close galaxy pair suggests that the cool gas reservoirs of the galaxies have been significantly depleted by the galaxy interaction. These observations therefore underscore the potential impact of galaxy interactions on the gaseous haloes around galaxies.

Blindness and partial sight in an elderly population.

PubMed Central

Gibson, J M; Lavery, J R; Rosenthal, A R

1986-01-01

A cross sectional, prevalence survey of eye disease in the population over 75 years old of Melton Mowbray has been used to examine the accuracy and completeness of the Blind and Partially Sighted Registers. The Blind Register had high sensitivity and specificity but was found to underestimate the prevalence of blindness by a factor of 1.1. The Partially Sighted Register had high specificity, but the sensitivity was only 50% and it underestimated the prevalence of partial sight by a factor of 1.5. Seven persons eligible for registration, but previously not registered, were found, two as blind and five as partially sighted. This represented 21% of the registrable visually impaired population. PMID:3756128

InSight Spacecraft Arrival

NASA Image and Video Library

2018-02-28

At Vandenberg Air Force Base in California, NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft arrives at the Astrotech processing facility. InSight was developed and built by Lockheed-Martin Space Systems in Denver, Colorado, and is scheduled for liftoff is May 5, 2018. InSight is the first mission to land on Mars and explore the Red Planet's deep interior. It will investigate processes that shaped the rocky planets of the inner solar system including Earth.

Exploratory flow visualization investigation of mast-mounted sights in presence of a rotor

NASA Technical Reports Server (NTRS)

Ghee, Terence A.; Kelley, Henry L.

1995-01-01

A flow visualization investigation with a laser light sheet system was conducted on a 27-percent-scale AH-64 attack helicopter model fitted with two mast-mounted sights in the langley 14- by 22-foot subsonic tunnel. The investigation was conducted to identify aerodynamic phenomena that may have contributed to adverse vibration encountered during full-scale flight of the AH-64D apache/longbow helicopter with an asymmetric mast-mounted sight. Symmetric and asymmetric mast-mounted sights oriented at several skew angles were tested at simulated forward and rearward flight speeds of 30 and 45 knots. A laser light sheet system was used to visualize the flow in planes parallel to and perpendicular to the free-stream flow. Analysis of these flow visualization data identified frequencies of flow patterns in the wake shed from the sight, the streamline angle at the sight, and the location where the shed wake crossed the rotor plane. Differences in wake structure were observed between the sight configurations and various skew angles. Analysis of lateral light sheet plane data implied significant vortex structure in the wake of the asymmetric mast-mounted sight in the configuration that produced maximum in-flight vibration. The data showed no significant vortex structure in the wake of the asymmetric and symmetric configurations that produced no increase in in-flight adverse vibration.

Inferring extinction risks from sighting records.

PubMed

Thompson, C J; Lee, T E; Stone, L; McCarthy, M A; Burgman, M A

2013-12-07

Estimating the probability that a species is extinct based on historical sighting records is important when deciding how much effort and money to invest in conservation policies. The framework we offer is more general than others in the literature to date. Our formulation allows for definite and uncertain observations, and thus better accommodates the realities of sighting record quality. Typically, the probability of observing a species given it is extant/extinct is challenging to define, especially when the possibility of a false observation is included. As such, we assume that observation probabilities derive from a representative probability density function. We incorporate this randomness in two different ways ("quenched" versus "annealed") using a framework that is equivalent to a Bayes formulation. The two methods can lead to significantly different estimates for extinction. In the case of definite sightings only, we provide an explicit deterministic calculation (in which observation probabilities are point estimates). Furthermore, our formulation replicates previous work in certain limiting cases. In the case of uncertain sightings, we allow for the possibility of several independent observational types (specimen, photographs, etc.). The method is applied to the Caribbean monk seal, Monachus tropicalis (which has only definite sightings), and synthetic data, with uncertain sightings. © 2013 Elsevier Ltd. All rights reserved.

JPL-20180307-INSIGHf-0001-Mars InSight Arrives at Vandenberg Air Force Base

NASA Image and Video Library

2018-03-07

NASA's InSight spacecraft arrived at Vandenberg Air Force Base, California, to begin final preparations for launch. InSight will be the first mission to look deep beneath the Martian surface, studying the planet's interior by listening for marsquakes and measuring its heat output. It will be the first planetary spacecraft to launch from this west coast launch facility. The launch period for InSight opens May 5, 2018 and continues through June 8, 2018.

InSight Spacecraft Arrival

NASA Image and Video Library

2018-02-28

After a U.S. Air Force C-17 aircraft arrived at Vandenberg Air Force Base in California, ground crews offload NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft designed to land on Mars. InSight was developed and built by Lockheed-Martin Space Systems in Denver, Colorado, and is scheduled for liftoff is May 5, 2018. InSight is the first mission to explore the Red Planet's deep interior. It will investigate processes that shaped the rocky planets of the inner solar system including Earth.

InSight Spacecraft Arrival

NASA Image and Video Library

2018-02-28

After arrival at Vandenberg Air Force Base in California, ground crews prepare NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft for transportation to the Astrotech processing facility. InSight was developed and built by Lockheed-Martin Space Systems in Denver, Colorado, and is scheduled for liftoff is May 5, 2018. InSight is the first mission to explore the deep interior of Mars. It will investigate processes that shaped the rocky planets of the inner solar system including Earth.

InSight Spacecraft Uncrating, Removal from Container, Lift Heat

NASA Image and Video Library

2018-03-01

At Vandenberg Air Force Base in California, NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft is uncrated inside the Astrotech processing facility. InSight was developed and built by Lockheed-Martin Space Systems in Denver, Colorado, and is scheduled for liftoff is May 5, 2018. InSight is the first mission to land on Mars and explore the Red Planet's deep interior. It will investigate processes that shaped the rocky planets of the inner solar system including Earth.

InSight Spacecraft Arrival

NASA Image and Video Library

2018-02-28

A U.S. Air Force C-17 aircraft arrives at Vandenberg Air Force Base in California carrying NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft designed to land on Mars. InSight was developed and built by Lockheed-Martin Space Systems in Denver, Colorado, and is scheduled for liftoff is May 5, 2018. InSight is the first mission to explore the Red Planet's deep interior. It will investigate processes that shaped the rocky planets of the inner solar system including Earth.

The subject-fixated coaxially sighted corneal light reflex: a clinical marker for centration of refractive treatments and devices.

PubMed

Chang, Daniel H; Waring, George O

2014-11-01

To describe the inconsistencies in definition, application, and usage of the ocular reference axes (optical axis, visual axis, line of sight, pupillary axis, and topographic axis) and angles (angle kappa, lambda, and alpha) and to propose a precise, reproducible, clinically defined reference marker and axis for centration of refractive treatments and devices. Perspective. Literature review of papers dealing with ocular reference axes, angles, and centration. The inconsistent definitions and usage of the current ocular axes, as derived from eye models, limit their clinical utility. With a clear understanding of Purkinje images and a defined alignment of the observer, light source/fixation target, and subject eye, the subject-fixated coaxially sighted corneal light reflex can be a clinically useful reference marker. The axis formed by connecting the subject-fixated coaxially sighted corneal light reflex and the fixation point, the subject-fixated coaxially sighted corneal light reflex axis, is independent of pupillary dilation and phakic status of the eye. The relationship of the subject-fixated coaxially sighted corneal light reflex axis to a refined definition of the visual axis without reference to nodal points, the foveal-fixation axis, is discussed. The displacement between the subject-fixated coaxially sighted corneal light reflex and pupil center is described not by an angle, but by a chord, here termed chord mu. The application of the subject-fixated coaxially sighted corneal light reflex to the surgical centration of refractive treatments and devices is discussed. As a clinically defined reference marker, the subject-fixated coaxially sighted corneal light reflex avoids the shortcomings of current ocular axes for clinical application and may contribute to better consensus in the literature and improved patient outcomes. Copyright © 2014 Elsevier Inc. All rights reserved.

InSight Atlas V Tower Roll

NASA Image and Video Library

2018-03-22

At Space Launch Complex 3 at Vandenberg Air Force Base in California, the gantry is rolled back on the United Launch Alliance (ULA) Atlas V to a Centaur upper stage aft stub adapter (ASA) and interstage adapter (ISA) for NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft to land on Mars. The next step will be arrival of InSight encapsulated in its payload faring for mating atop the rocket. InSight is the first mission to explore the Red Planet's deep interior. InSight is scheduled for liftoff May 5, 2018. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. InSight will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the InSight mission for the agency’s Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by its Marshall Space Flight Center in Huntsville, Alabama. The spacecraft, including cruise stage and lander, was built and tested by Lockheed Martin Space in Denver. Several European partners, including France's space agency, the Centre National d'Étude Spatiales, and the German Aerospace Center, are supporting the mission. United Launch Alliance of Centennial, Colorado, is providing the Atlas V launch service. NASA’s Launch Services Program, based at its Kennedy Space Center in Florida, is responsible for launch management.

A geographic analysis of the status of mountain lions in Oklahoma

USGS Publications Warehouse

Pike, J.R.; Shaw, J.H.; Leslie, David M.; Shaw, M.G.

1999-01-01

The geographic distribution of sightings and sign of mountain lions (Puma concolor) in Oklahoma was investigated. Mail survey questionnaires were sent to natural resource professionals throughout Oklahoma to gather temporal and spatial information on sightings of mountain lions from 1985 to 1995. We used a geographic information system (GIS) to compare locations of sightings and sign in the state with ecoregions, deer harvest, human population densities, locations of licensed owners and breeders of mountain lions, and generalized topography. Sightings and sign of mountain lions occurred significantly more often in the Central Rolling Red Plains than elsewhere in the state. Sightings of mountain lions increased with total deer harvest statewide (R2=0.828, P<0.001). Numbers of sightings of mountain lions were correlated negatively with density of the human population (R2=0.885, P=0.017). Surveys are a valuable method to assess the status of rare wildlife species when other methods are not available and when those receiving the survey are qualified.

Can pictures promote the acquisition of sight-word reading? An evaluation of two potential instructional strategies.

PubMed

Richardson, Amy R; Lerman, Dorothea C; Nissen, Melissa A; Luck, Kally M; Neal, Ashley E; Bao, Shimin; Tsami, Loukia

2017-01-01

Sight-word instruction can be a useful supplement to phonics-based methods under some circumstances. Nonetheless, few studies have evaluated the conditions under which pictures may be used successfully to teach sight-word reading. In this study, we extended prior research by examining two potential strategies for reducing the effects of overshadowing when using picture prompts. Five children with developmental disabilities and two typically developing children participated. In the first experiment, the therapist embedded sight words within pictures but gradually faded in the pictures as needed using a least-to-most prompting hierarchy. In the second experiment, the therapist embedded text-to-picture matching within the sight-word reading sessions. Results suggested that these strategies reduced the interference typically observed with picture prompts and enhanced performance during teaching sessions for the majority of participants. Text-to-picture matching also accelerated mastery of the sight words relative to a condition under which the therapist presented text without pictures. © 2016 Society for the Experimental Analysis of Behavior.

Replicability of sight word training and phonics training in poor readers: a randomised controlled trial

PubMed Central

Kohnen, S; Jones, K; Eve, P; Banales, E; Larsen, L; Castles, A

2015-01-01

Given the importance of effective treatments for children with reading impairment, paired with growing concern about the lack of scientific replication in psychological science, the aim of this study was to replicate a quasi-randomised trial of sight word and phonics training using a randomised controlled trial (RCT) design. One group of poor readers (N = 41) did 8 weeks of phonics training (i.e., phonological decoding) and then 8 weeks of sight word training (i.e., whole-word recognition). A second group did the reverse order of training. Sight word and phonics training each had a large and significant valid treatment effect on trained irregular words and word reading fluency. In addition, combined sight word and phonics training had a moderate and significant valid treatment effect on nonword reading accuracy and fluency. These findings demonstrate the reliability of both phonics and sight word training in treating poor readers in an era where the importance of scientific reliability is under close scrutiny. PMID:26019992

Turning the InSight Lander Science Deck

NASA Image and Video Library

2015-05-27

The science deck of NASA's InSight lander is being turned over in this April 29, 2015, photo from InSight assembly and testing operations inside a clean room at Lockheed Martin Space Systems, Denver. The large circular component on the deck is the protective covering to be placed over InSight's seismometer after the seismometer is placed directly onto the Martian ground. InSight, for Interior Exploration Using Seismic Investigations, Geodesy and Heat Transport, is scheduled for launch in March 2016 and landing in September 2016. It will study the deep interior of Mars to advance understanding of the early history of all rocky planets, including Earth. Note: After thorough examination, NASA managers have decided to suspend the planned March 2016 launch of the Interior Exploration using Seismic Investigations Geodesy and Heat Transport (InSight) mission. The decision follows unsuccessful attempts to repair a leak in a section of the prime instrument in the science payload. http://photojournal.jpl.nasa.gov/catalog/PIA19670

Violence reduction and assailant control with integral laser-sighted police pistols

NASA Astrophysics Data System (ADS)

Houde-Walter, Will

1997-01-01

Laser sighting systems have been proven effective in reducing violence during tactical police operations. the laser sight plays two roles, one as an extremely intimidating pointer that informs the assailant of potential bullet placement and the other as a low light sighting device to increase the probability of hitting the target. Laser sighting gives the officer an additional alternative to lethal force. The statistical base of police data from laser assisted confrontations indicates that the assailant will capitulate, even when heavily armed, in the vast majority of cases. In this paper, we will introduce a new police technology; micro-visible diode lasers for semi- automatic piston recoil spring guide mounting of laser sights. This approach provides many advantages as the laser is concealed and protected by the pistol frame and the point of aim is aligned at the same mounting locations as the barrel. The laser can be field issues and installed or removed from the pistol in a minute with no permanent modification to the pistol.

InSight Atlas V ISA-ASA Lift and Mate

NASA Image and Video Library

2018-03-05

At Vandenberg Air Force Base in California, the aft stub adapter (ASA) and interstage adapter (ISA) for a United Launch Alliance (ULA) Atlas V arrives at Space Launch Complex 3. The launch vehicle will send NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft to land on Mars. InSight is the first mission to explore the Red Planet's deep interior. InSight is scheduled for liftoff May 5, 2018. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. InSight will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the InSight mission for the agency’s Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by its Marshall Space Flight Center in Huntsville, Alabama. The spacecraft, including cruise stage and lander, was built and tested by Lockheed Martin Space in Denver. Several European partners, including France's space agency, the Centre National d'Étude Spatiales, and the German Aerospace Center, are supporting the mission. United Launch Alliance of Centennial, Colorado, is providing the Atlas V launch service. NASA’s Launch Services Program, based at its Kennedy Space Center in Florida, is responsible for launch management.

InSight Atlas V ISA-ASA Transport

NASA Image and Video Library

2018-03-05

At Vandenberg Air Force Base in California, the aft stub adapter (ASA) and interstage adapter (ISA) for a United Launch Alliance (ULA) Atlas V arrive at Space Launch Complex 3. The launch vehicle will send NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft to land on Mars. InSight is the first mission to explore the Red Planet's deep interior. InSight is scheduled for liftoff May 5, 2018. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. InSight will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the InSight mission for the agency’s Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by its Marshall Space Flight Center in Huntsville, Alabama. The spacecraft, including cruise stage and lander, was built and tested by Lockheed Martin Space in Denver. Several European partners, including France's space agency, the Centre National d'Étude Spatiales, and the German Aerospace Center, are supporting the mission. United Launch Alliance of Centennial, Colorado, is providing the Atlas V launch service. NASA’s Launch Services Program, based at its Kennedy Space Center in Florida, is responsible for launch management.

InSight Atlas V ISA-ASA Transport

NASA Image and Video Library

2018-03-05

At Vandenberg Air Force Base in California, the aft stub adapter (ASA) and interstage adapter (ISA) for a United Launch Alliance (ULA) Atlas V rocket are transported to Space Launch Complex 3. The launch vehicle will send NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft to land on Mars. InSight is the first mission to explore the Red Planet's deep interior. InSight is scheduled for liftoff May 5, 2018. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. InSight will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the InSight mission for the agency’s Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by its Marshall Space Flight Center in Huntsville, Alabama. The spacecraft, including cruise stage and lander, was built and tested by Lockheed Martin Space in Denver. Several European partners, including France's space agency, the Centre National d'Étude Spatiales, and the German Aerospace Center, are supporting the mission. United Launch Alliance of Centennial, Colorado, is providing the Atlas V launch service. NASA’s Launch Services Program, based at its Kennedy Space Center in Florida, is responsible for launch management.

Administrator Bridenstine: InSight Will Map the Inside of Mars

NASA Image and Video Library

2018-05-05

NASA Administrator Jim Bridenstine shares thoughts on the Mars InSight mission, the search for evidence of life beyond Earth, returning humans to the Moon and why Earth is his favorite planet. To learn more about InSight, visit https://mars.nasa.gov/insight/.

Aerogel Antennas Communications Study Using Error Vector Magnitude Measurements

NASA Technical Reports Server (NTRS)

Miranda, Felix A.; Mueller, Carl H.; Meador, Mary Ann B.

2014-01-01

This presentation discusses an aerogel antennas communication study using error vector magnitude (EVM) measurements. The study was performed using 2x4 element polyimide (PI) aerogel-based phased arrays designed for operation at 5 GHz as transmit (Tx) and receive (Rx) antennas separated by a line of sight (LOS) distance of 8.5 meters. The results of the EVM measurements demonstrate that polyimide aerogel antennas work appropriately to support digital communication links with typically used modulation schemes such as QPSK and 4 DQPSK. As such, PI aerogel antennas with higher gain, larger bandwidth and lower mass than typically used microwave laminates could be suitable to enable aerospace-to- ground communication links with enough channel capacity to support voice, data and video links from CubeSats, unmanned air vehicles (UAV), and commercial aircraft.

Aerogel Antennas Communications Study Using Error Vector Magnitude Measurements

NASA Technical Reports Server (NTRS)

Miranda, Felix A.; Mueller, Carl H.; Meador, Mary Ann B.

2014-01-01

This paper discusses an aerogel antennas communication study using error vector magnitude (EVM) measurements. The study was performed using 4x2 element polyimide (PI) aerogel-based phased arrays designed for operation at 5 GHz as transmit (Tx) and receive (Rx) antennas separated by a line of sight (LOS) distance of 8.5 meters. The results of the EVM measurements demonstrate that polyimide aerogel antennas work appropriately to support digital communication links with typically used modulation schemes such as QPSK and pi/4 DQPSK. As such, PI aerogel antennas with higher gain, larger bandwidth and lower mass than typically used microwave laminates could be suitable to enable aerospace-to-ground communication links with enough channel capacity to support voice, data and video links from cubesats, unmanned air vehicles (UAV), and commercial aircraft.

IPC two-color analysis of x ray galaxy clusters

NASA Technical Reports Server (NTRS)

White, Raymond E., III

1990-01-01

The mass distributions were determined of several clusters of galaxies by using X ray surface brightness data from the Einstein Observatory Imaging Proportional Counter (IPC). Determining cluster mass distributions is important for constraining the nature of the dark matter which dominates the mass of galaxies, galaxy clusters, and the Universe. Galaxy clusters are permeated with hot gas in hydrostatic equilibrium with the gravitational potentials of the clusters. Cluster mass distributions can be determined from x ray observations of cluster gas by using the equation of hydrostatic equilibrium and knowledge of the density and temperature structure of the gas. The x ray surface brightness at some distance from the cluster is the result of the volume x ray emissivity being integrated along the line of sight in the cluster.

The Discovery of an Evolving Dust Scattered X-ray Halo Around GRB 031203

NASA Technical Reports Server (NTRS)

Vaughan, S.; Willingale, R.; OBrien, P. T.; Osborne, J. P.; Reeves, J. N.; Levan, A. J.; Watson, M. G.; Tedds, J. A.; Watson, D.; Santos-Lleo, M.

2003-01-01

We report the first detection of a time-dependent, dust-scattered X-ray halo around a gamma-ray burst. GRB3 031203 was observed by XMM-Newton starting six hours after the burst. The halo appeared as concentric ring-like structures centered on the GRB location. The radii of these structures increased with time as t(sup 1/2), consistent with small-angle X-ray scattering caused by a large column of dust along the line of sight to a cosmologically distant GRB. The rings are due to dust concentrated in two distinct slabs in the Galaxy located at distances of 880 and 1390 pc, consistent with known Galactic features. The halo brightness implies an initial soft X-ray pulse consistent with the observed GRB.

Developing Automated Spectral Analysis Tools for Interstellar Features Extractionto Support Construction of the 3D ISM Map

NASA Astrophysics Data System (ADS)

Puspitarini, L.; Lallement, R.; Monreal-Ibero, A.; Chen, H.-C.; Malasan, H. L.; Aprilia; Arifyanto, M. I.; Irfan, M.

2018-04-01

One of the ways to obtain a detailed 3D ISM map is by gathering interstellar (IS) absorption data toward widely distributed background target stars at known distances (line-of-sight/LOS data). The radial and angular evolution of the LOS measurements allow the inference of the ISM spatial distribution. For a better spatial resolution, one needs a large number of the LOS data. It requires building fast tools to measure IS absorption. One of the tools is a global analysis that fit two different diffuse interstellar bands (DIBs) simultaneously. We derived the equivalent width (EW) ratio of the two DIBs recorded in each spectrum of target stars. The ratio variability can be used to study IS environmental conditions or to detect DIB family.

Probing the Milky Way electron density using multi-messenger astronomy

NASA Astrophysics Data System (ADS)

Breivik, Katelyn; Larson, Shane

2015-04-01

Multi-messenger observations of ultra-compact binaries in both gravitational waves and electromagnetic radiation supply highly complementary information, providing new ways of characterizing the internal dynamics of these systems, as well as new probes of the galaxy itself. Electron density models, used in pulsar distance measurements via the electron dispersion measure, are currently not well constrained. Simultaneous radio and gravitational wave observations of pulsars in binaries provide a method of measuring the average electron density along the line of sight to the pulsar, thus giving a new method for constraining current electron density models. We present this method and assess its viability with simulations of the compact binary component of the Milky Way using the public domain binary evolution code, BSE. This work is supported by NASA Award NNX13AM10G.

Experimental far-field imaging properties of a ~5-μm diameter spherical lens.

PubMed

Ye, Ran; Ye, Yong-Hong; Ma, Hui Feng; Ma, Jun; Wang, Bin; Yao, Jie; Liu, Shuai; Cao, Lingling; Xu, Huanhuan; Zhang, Jia-Yu

2013-06-01

Microscale lenses are mostly used as near-sighted lenses. The far-field imaging properties of a microscale spherical lens, where the lens is spatially separated from the object, are experimentally studied. Our experimental results show that, for a blu-ray disc (an object) whose spacing is 300 nm, the lens can magnify the stripe patterns of the disc when the lens is spatially separated from the object. In the experimentally tested range (0-14 μm), all the magnified images are virtual images. When the distance is increased from 0 to 14 μm the magnification decreases from 1.47× to 1.20× and the field of view increases from 3.8 to 12.2 μm. The image magnification cannot be described by standard geometrical optics.

X-ray transport and radiation response assessment (XTRRA) experiments at the National Ignition Facility.

PubMed

Fournier, K B; Brown, C G; Yeoman, M F; Fisher, J H; Seiler, S W; Hinshelwood, D; Compton, S; Holdener, F R; Kemp, G E; Newlander, C D; Gilliam, R P; Froula, N; Lilly, M; Davis, J F; Lerch, Maj A; Blue, B E

2016-11-01

Our team has developed an experimental platform to evaluate the x-ray-generated stress and impulse in materials. Experimental activities include x-ray source development, design of the sample mounting hardware and sensors interfaced to the National Ignition Facility's diagnostics insertion system, and system integration into the facility. This paper focuses on the X-ray Transport and Radiation Response Assessment (XTRRA) test cassettes built for these experiments. The test cassette is designed to position six samples at three predetermined distances from the source, each known to within ±1% accuracy. Built-in calorimeters give in situ measurements of the x-ray environment along the sample lines of sight. The measured accuracy of sample responses as well as planned modifications to the XTRRA cassette is discussed.

A New Reddening Law for M4

NASA Astrophysics Data System (ADS)

Hendricks, Benjamin; Stetson, Peter B.; VandenBerg, Don A.; Dall'Ora, Massimo

2012-07-01

We have used a combination of broadband near-infrared and optical Johnson-Cousins photometry to study the dust properties in the line of sight to the Galactic globular cluster M4. We have investigated the reddening effects in terms of absolute strength and variation across the cluster field, as well as the shape of the reddening law defined by the type of dust. All three aspects had been poorly defined for this system and, consequently, there has been controversy about the absolute distance to this globular cluster, which is closest to the Sun. Here, we determine the ratio of absolute to selective extinction (RV ) in the line of sight toward M4, which is known to be a useful indicator for the type of dust and therefore characterizes the applicable reddening law. Our method is independent of age assumptions and appears to be significantly more precise and accurate than previous approaches. We obtain AV /E(B - V) = 3.76 ± 0.07 (random error) for the dust in the line of sight to M4 for our set of filters. That corresponds to a dust-type parameter RV = 3.62 ± 0.07 in the Cardelli et al. reddening law. With this value, the distance to M4 is found to be 1.80 ± 0.05 kpc, corresponding to a true distance modulus of (m - M)0 = 11.28 ± 0.06 (random error). A reddening map for M4 has been created, which reveals a spatial differential reddening of δE(B - V) >= 0.2 mag across the field within 10' around the cluster center; this is about 50% of the total mean reddening, which we have determined to be E(B - V) = 0.37 ± 0.01. In order to provide accurate zero points for the extinction coefficients of our photometric filters, we investigated the impact of stellar parameters such as temperature, surface gravity, and metallicity on the extinction properties and the necessary corrections in different bandpasses. Using both synthetic ATLAS9 spectra and observed spectral energy distributions, we found similarly sized effects for the range of temperature and surface gravity typical of globular cluster stars: each causes a change of about 3% in the necessary correction factor for each filter combination. Interestingly, variations in the metallicity cause effects of the same order when the assumed value is changed from the solar metallicity ([Fe/H] = 0.0) to [Fe/H] = -2.5. The systematic differences between the reddening corrections for a typical main-sequence turnoff star in a metal poor globular cluster and a Vega-like star are even stronger (~5%). We compared the results from synthetic spectra to those obtained with observed spectral energy distributions and found significant differences for temperatures lower than ~5000 K. We have attributed these discrepancies to the inadequate treatment of some molecular bands in the B filter within the ATLAS9 models. Fortunately, these differences do not affect the principal astrophysical conclusions in this study, which are based on stars hotter than 5000 K. From our calculations, we provide extinction zero points for Johnson-Cousins and Two Micron All Sky Survey filters, spanning a wide range of stellar parameters and dust types. These extinction tables are suited for accurate, object-specific extinction corrections.

Testing the Distance Scale of the Gaia TGAS Catalogue by the Kinematic Method

NASA Astrophysics Data System (ADS)

Bobylev, V. V.; Bajkova, A. T.

2018-03-01

We have studied the simultaneous and separate solutions of the basic kinematic equations obtained using the stellar velocities calculated on the basis of data from the Gaia TGAS and RAVE5 catalogues. By comparing the values of Ω'0 found by separately analyzing only the line-of-sight velocities of stars and only their proper motions, we have determined the distance scale correction factor p to be close to unity, 0.97 ± 0.04. Based on the proper motions of stars from the Gaia TGAS catalogue with relative trigonometric parallax errors less than 10% (they are at a mean distance of 226 pc), we have found the components of the group velocity vector for the sample stars relative to the Sun ( U, V, W)⊙ = (9.28, 20.35, 7.36) ± (0.05, 0.07, 0.05) km s-1, the angular velocity of Galactic rotation Ω0 = 27.24 ± 0.30 km s-1 kpc-1, and its first derivative Ω'0 = -3.77 ± 0.06 km s-1 kpc-2; here, the circular rotation velocity of the Sun around the Galactic center is V 0 = 218 ± 6 km s-1 kpc (for the adopted distance R 0 = 8.0 ± 0.2 kpc), while the Oort constants are A = 15.07 ± 0.25 km s-1 kpc-1 and B = -12.17 ± 0.39 km s-1 kpc-1, p = 0.98 ± 0.08. The kinematics of Gaia TGAS stars with parallax errors more than 10% has been studied by invoking the distances from a paper by Astraatmadja and Bailer-Jones that were corrected for the Lutz-Kelker bias. We show that the second derivative of the angular velocity of Galactic rotation Ω'0 = 0.864 ± 0.021 km s-1 kpc-3 is well determined from stars at a mean distance of 537 pc. On the whole, we have found that the distances of stars from the Gaia TGAS catalogue calculated using their trigonometric parallaxes do not require any additional correction factor.

The Spatial Cognition of Blind Pedestrians.

ERIC Educational Resources Information Center

Hollyfield, Rebecca L.; Foulke, Emerson

1983-01-01

Four groups (sighted, blindfolded sighted, legally blind, and blind) of adults were trained to traverse a five-block route in a residential neighborhood and were then asked to reconstruct the route from memory. Results showed the blind and sighted adults demonstrated similar abilities to learn routes but showed significant differences in memorial…

Factors Related to Sight-Reading Accuracy: A Meta-Analysis

ERIC Educational Resources Information Center

Mishra, Jennifer

2014-01-01

The purpose of this meta-analysis was to determine the extent of the overall relationship between previously tested variables and sight-reading. An exhaustive survey of the available research literature was conducted resulting in 92 research studies that reported correlations between sight-reading and another variable. Variables ("n" =…

InSight, a Mars MIssion Artist Concept

NASA Image and Video Library

2012-02-28

This artist rendition is of the Interior exploration using Seismic Investigations, Geodesy and Heat Transport InSight Lander. InSight proposes to place a single geophysical lander on Mars to study its deep interior. Note: After thorough examination, NASA managers have decided to suspend the planned March 2016 launch of the Interior Exploration using Seismic Investigations Geodesy and Heat Transport (InSight) mission. The decision follows unsuccessful attempts to repair a leak in a section of the prime instrument in the science payload. http://photojournal.jpl.nasa.gov/catalog/PIA13958

InSight Prelaunch Overview

NASA Image and Video Library

2018-05-03

Members of the media and social media participants attended the NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, prelaunch briefing at Vandenberg Air Force Base in California. The presentation focused on InSight Mars lander. InSight is scheduled for liftoff May 5, 2018, atop a United Launch Alliance (ULA) Atlas V rocket from Space Launch Complex 3 at Vandenberg. The spacecraft will be the first mission to look deep beneath the Martian surface studying the planet's interior by measuring its heat output and listen for marsquakes.

InSight Spacecraft Uncrating, Removal from Container, Lift Heat

NASA Image and Video Library

2018-03-01

Inside the Astrotech processing facility at Vandenberg Air Force Base in California, the heatshield for NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft is removed from protective wrapping. InSight was developed and built by Lockheed-Martin Space Systems in Denver, Colorado, and is scheduled for liftoff is May 5, 2018. InSight is the first mission to land on Mars and explore the Red Planet's deep interior. It will investigate processes that shaped the rocky planets of the inner solar system including Earth.

InSight Spacecraft Uncrating, Removal from Container, Lift Heat

NASA Image and Video Library

2018-03-01

Inside the Astrotech processing facility at Vandenberg Air Force Base in California, technicians and engineers inspect the heatshield for NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft. InSight was developed and built by Lockheed-Martin Space Systems in Denver, Colorado, and is scheduled for liftoff is May 5, 2018. InSight is the first mission to land on Mars and explore the Red Planet's deep interior. It will investigate processes that shaped the rocky planets of the inner solar system including Earth.

InSight Spacecraft Uncrating, Removal from Container, Lift Heat

NASA Image and Video Library

2018-03-01

Inside the Astrotech processing facility at Vandenberg Air Force Base in California, the heatshield for NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft has been removed from protective wrapping. InSight was developed and built by Lockheed-Martin Space Systems in Denver, Colorado, and is scheduled for liftoff is May 5, 2018. InSight is the first mission to land on Mars and explore the Red Planet's deep interior. It will investigate processes that shaped the rocky planets of the inner solar system including Earth.

Resolving the Azimuthal Ambiguity in Vector Magnetogram Data with the Divergence-Free Condition: Theoretical Examination

NASA Technical Reports Server (NTRS)

Crouch, A.; Barnes, G.

2008-01-01

We demonstrate that the azimuthal ambiguity that is present in solar vector magnetogram data can be resolved with line-of-sight and horizontal heliographic derivative information by using the divergence-free property of magnetic fields without additional assumptions. We discuss the specific derivative information that is sufficient to resolve the ambiguity away from disk center, with particular emphasis on the line-of-sight derivative of the various components of the magnetic field. Conversely, we also show cases where ambiguity resolution fails because sufficient line-of-sight derivative information is not available. For example, knowledge of only the line-of-sight derivative of the line-of-sight component of the field is not sufficient to resolve the ambiguity away from disk center.

InSight Media Day Preparation

NASA Image and Video Library

2018-04-05

NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, is in a clean room inside the Astrotech processing facility at Vandenberg Air Force Base in California. InSight is scheduled for liftoff on a United Launch Alliance Atlas V rocket May 5, 2018. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. InSight will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the InSight mission for the agency’s Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by its Marshall Space Flight Center in Huntsville, Alabama. The spacecraft, including cruise stage and lander, was built and tested by Lockheed Martin Space in Denver. Several European partners, including France's space agency, the Centre National d'Étude Spatiales, and the German Aerospace Center, are supporting the mission. United Launch Alliance of Centennial, Colorado, is providing the Atlas V launch service. NASA’s Launch Services Program, based at its Kennedy Space Center in Florida, is responsible for launch management.

NEUTRAL HYDROGEN OPTICAL DEPTH NEAR STAR-FORMING GALAXIES AT z Almost-Equal-To 2.4 IN THE KECK BARYONIC STRUCTURE SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rakic, Olivera; Schaye, Joop; Steidel, Charles C.

We study the interface between galaxies and the intergalactic medium by measuring the absorption by neutral hydrogen in the vicinity of star-forming galaxies at z Almost-Equal-To 2.4. Our sample consists of 679 rest-frame UV-selected galaxies with spectroscopic redshifts that have impact parameters <2 (proper) Mpc to the line of sight of one of the 15 bright, background QSOs and that fall within the redshift range of its Ly{alpha} forest. We present the first two-dimensional maps of the absorption around galaxies, plotting the median Ly{alpha} pixel optical depth as a function of transverse and line-of-sight separation from galaxies. The Ly{alpha} opticalmore » depths are measured using an automatic algorithm that takes advantage of all available Lyman series lines. The median optical depth, and hence the median density of atomic hydrogen, drops by more than an order of magnitude around 100 kpc, which is similar to the virial radius of the halos thought to host the galaxies. The median remains enhanced, at the >3{sigma} level, out to at least 2.8 Mpc (i.e., >9 comoving Mpc), but the scatter at a given distance is large compared with the median excess optical depth, suggesting that the gas is clumpy. Within 100 (200) kpc, and over {+-}165 km s{sup -1}, the covering fraction of gas with Ly{alpha} optical depth greater than unity is 100{sup +0}{sub -32}% (66% {+-} 16%). Absorbers with {tau}{sub Ly{alpha}} > 0.1 are typically closer to galaxies than random. The mean galaxy overdensity around absorbers increases with the optical depth and also as the length scale over which the galaxy overdensity is evaluated is decreased. Absorbers with {tau}{sub Ly{alpha}} {approx} 1 reside in regions where the galaxy number density is close to the cosmic mean on scales {>=}0.25 Mpc. We clearly detect two types of redshift space anisotropies. On scales <200 km s{sup -1}, or <1 Mpc, the absorption is stronger along the line of sight than in the transverse direction. This 'finger of God' effect may be due to redshift errors, but is probably dominated by gas motions within or very close to the halos. On the other hand, on scales of 1.4-2.0 Mpc the absorption is compressed along the line of sight (with >3{sigma} significance), an effect that we attribute to large-scale infall (i.e., the Kaiser effect).« less

A Deep Search with HST for Late Time Supernova Signatures in the Hosts of XRF 011030 and XRF 020427

NASA Technical Reports Server (NTRS)

Patel, Sandeep; Kouveliotou, Chryssa; Levan, Andrew; Fruchter, Andrew; Rol, Evert; Rhoads, James; Gorosabel, Javier; Ramirez-Ruiz, Enrico; Hjorth, Jens; Wijers, Ralph

2004-01-01

X-ray Flashes (XRFs), are, like Gamma-Ray Bursts (GRBs) thought to signal the collapse of massive stars in distant galaxies. Many models posit that the isotropic equivalent energies of XRFs are lower than those for GRBs, such that they are visible hom a reduced range of distances when compared with GRBs. Here we present the results of two epoch Hubble Space Telescope imaging of two XRFs. These images taken approximately 45 and 200 days post bust reveal no evidence for an associated supernova in either case. Supernovae such as SN 1998bw would have been visible out to z approximately 1.5 in each case, while faint supernovae such as SN 2002ap would be visible to z approximately 1. At these distances the bursts would not fit the observed correlations between E(sub p) and E(sub iso) and would have required extremely luminous X-ray afterglows. We conclude that should these XRFs reside at low redshift, it is necessary either that their line of sight is heavily extinguished, or that XRFs, unlike GRBs do not have temporally coincident supernovae.

TriAnd and its siblings: satellites of satellites in the Milky Way halo

NASA Astrophysics Data System (ADS)

Deason, A. J.; Belokurov, V.; Hamren, K. M.; Koposov, S. E.; Gilbert, K. M.; Beaton, R. L.; Dorman, C. E.; Guhathakurta, P.; Majewski, S. R.; Cunningham, E. C.

2014-11-01

We explore the Triangulum-Andromeda (TriAnd) overdensity in the SPLASH (Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo) and SEGUE (the Sloan Extension for Galactic Understanding and Exploration) spectroscopic surveys. Milky Way main-sequence turn-off stars in the SPLASH survey reveal that the TriAnd overdensity and the recently discovered Pan-Andromeda Archaeological Survey (PAndAS) stream share a common heliocentric distance (D ˜ 20 kpc), position on the sky, and line-of-sight velocity (VGSR ˜ 50 km s-1). Similarly, A-type, giant, and main-sequence turn-off stars selected from the SEGUE survey in the vicinity of the Segue 2 satellite show that TriAnd is prevalent in these fields, with a velocity and distance similar to Segue 2. The coincidence of the PAndAS stream and Segue 2 satellite in positional and velocity space to TriAnd suggests that these substructures are all associated, and may be a fossil record of group-infall on to the Milky Way halo. In this scenario, the Segue 2 satellite and PAndAS stream are `satellites of satellites', and the large, metal-rich TriAnd overdensity is the remains of the group central.

A New Giant Stellar Structure in the Outer Halo of M31

NASA Astrophysics Data System (ADS)

Zucker, Daniel B.; Kniazev, Alexei Y.; Bell, Eric F.; Martínez-Delgado, David; Grebel, Eva K.; Rix, Hans-Walter; Rockosi, Constance M.; Holtzman, Jon A.; Walterbos, Rene A. M.; Ivezić, Željko; Brinkmann, J.; Brewington, Howard; Harvanek, Michael; Kleinman, S. J.; Krzesinski, Jurek; Lamb, Don Q.; Long, Dan; Newman, Peter R.; Nitta, Atsuko; Snedden, Stephanie A.

2004-09-01

The Sloan Digital Sky Survey has revealed an overdensity of luminous red giant stars ~3° (40 projected kpc) to the northeast of M31, which we have called Andromeda NE. The line-of-sight distance to Andromeda NE is within ~50 kpc of M31; Andromeda NE is not a physically unrelated projection. Andromeda NE has a g-band absolute magnitude of ~-11.6 and a central surface brightness of ~29 mag arcsec-2, making it nearly 2 orders of magnitude more diffuse than any known Local Group dwarf galaxy at that luminosity. Based on its distance and morphology, Andromeda NE is likely undergoing tidal disruption. Andromeda NE's red giant branch color is unlike that of M31's present-day outer disk or the stellar stream reported by Ibata et al., arguing against a direct link between Andromeda NE and these structures. However, Andromeda NE has a red giant branch color similar to that of the G1 clump; it is possible that these structures are both material torn off of M31's disk in the distant past or that these are both part of one ancient stellar stream.

The Capacity Gain of Orbital Angular Momentum Based Multiple-Input-Multiple-Output System

PubMed Central

Zhang, Zhuofan; Zheng, Shilie; Chen, Yiling; Jin, Xiaofeng; Chi, Hao; Zhang, Xianmin

2016-01-01

Wireless communication using electromagnetic wave carrying orbital angular momentum (OAM) has attracted increasing interest in recent years, and its potential to increase channel capacity has been explored widely. In this paper, we compare the technique of using uniform linear array consist of circular traveling-wave OAM antennas for multiplexing with the conventional multiple-in-multiple-out (MIMO) communication method, and numerical results show that the OAM based MIMO system can increase channel capacity while communication distance is long enough. An equivalent model is proposed to illustrate that the OAM multiplexing system is equivalent to a conventional MIMO system with a larger element spacing, which means OAM waves could decrease the spatial correlation of MIMO channel. In addition, the effects of some system parameters, such as OAM state interval and element spacing, on the capacity advantage of OAM based MIMO are also investigated. Our results reveal that OAM waves are complementary with MIMO method. OAM waves multiplexing is suitable for long-distance line-of-sight (LoS) communications or communications in open area where the multi-path effect is weak and can be used in massive MIMO systems as well. PMID:27146453

The design of common aperture and multi-band optical system based on day light telescope

NASA Astrophysics Data System (ADS)

Chen, Jiao; Wang, Ling; Zhang, Bo; Teng, Guoqi; Wang, Meng

2017-02-01

As the development of electro-optical weapon system, the technique of common path and multi-sensor are used popular, and becoming a trend. According to the requirement of miniaturization and lightweight for electro-optical stabilized sighting system, a day light telescope/television viewing-aim system/ laser ranger has been designed in this thesis, which has common aperture. Thus integration scheme of multi-band and common aperture has been adopted. A day light telescope has been presented, which magnification is 8, field of view is 6°, and distance of exit pupil is more than 20mm. For 1/3" CCD, television viewing-aim system which has 156mm focal length, has been completed. In addition, laser ranging system has been designed, with 10km raging distance. This paper outlines its principle which used day light telescope as optical reference of correcting the optical axis. Besides, by means of shared objective, reserved image with inverting prism and coating beam-splitting film on the inclined plane of the cube prism, the system has been applied to electro-optical weapon system, with high-resolution of imaging and high-precision ranging.

The performance of bonobos (Pan paniscus), chimpanzees (Pan troglodytes), and orangutans (Pongo pygmaeus) in two versions of an object-choice task.

PubMed

Mulcahy, Nicholas J; Call, Josep

2009-08-01

The object-choice task tests animals' ability to use human-given cues to find a hidden reward located in 1 of 2 (or more) containers. Great apes are generally unskillful in this task whereas other species including dogs (Canis familiaris) and goats (Capra hircus) can use human-given cues to locate the reward. However, great apes are typically positioned proximal to the containers when receiving the experimenter's cue whereas other species are invariably positioned distally. The authors investigated how the position of the subject, the human giving the cue and the containers (and the distance among them) affected the performance of 19 captive great apes. Compared to the proximal condition, the distal condition involved larger distances and, critically, it reduced the potential ambiguity of the cues as well as the strong influence that the sight of the containers may have had when subjects received the cue. Subjects were far more successful in the distal compared to the proximal condition. The authors suggest several possibilities to account for this difference and discuss our findings in relation to previous and future object-choice research. Copyright 2009 APA, all rights reserved.

Astronomers, Transits of Venus, and the Birth of Experimental Psychology

NASA Astrophysics Data System (ADS)

Sheehan, William; Thurber, S.

2012-01-01

The eighteenth century transits of Venus were regarded as the most important astronomical events of their era. Halley's expectation was that by observing the contact points between the limbs of Venus and the Sun, this distance could be determined to an accuracy of one part in 500. But in the event, it proved otherwise. But, as the British historian Agnes Clerke wrote in 1902: "A transit of Venus seems, at first sight, full of promise for solving the problem of the sun's distance. For nothing would appear easier than to determine exactly either the duration of the passage of a small, dark orb across a large brilliant disc, or the instant of its entry upon or exit from it". But in that word `exactly' what snares and pitfalls lie hid!” In the post-mortem analysis of the disappointing results, astronomers devoted a great deal of effort to understand the sources of errors. They rehearsed their observational techniques by observing, under strictly controlled conditions, transits of artificial planets across artificial Suns, and studied such parameters as attention and reflex reaction. In the process, the transits of Venus provided an important impetus to the early development of experimental psychology.

Patterns of Individual Variation in Visual Pathway Structure and Function in the Sighted and Blind

PubMed Central

Datta, Ritobrato; Benson, Noah C.; Prasad, Sashank; Jacobson, Samuel G.; Cideciyan, Artur V.; Bridge, Holly; Watkins, Kate E.; Butt, Omar H.; Dain, Aleksandra S.; Brandes, Lauren; Gennatas, Efstathios D.

2016-01-01

Many structural and functional brain alterations accompany blindness, with substantial individual variation in these effects. In normally sighted people, there is correlated individual variation in some visual pathway structures. Here we examined if the changes in brain anatomy produced by blindness alter the patterns of anatomical variation found in the sighted. We derived eight measures of central visual pathway anatomy from a structural image of the brain from 59 sighted and 53 blind people. These measures showed highly significant differences in mean size between the sighted and blind cohorts. When we examined the measurements across individuals within each group we found three clusters of correlated variation, with V1 surface area and pericalcarine volume linked, and independent of the thickness of V1 cortex. These two clusters were in turn relatively independent of the volumes of the optic chiasm and lateral geniculate nucleus. This same pattern of variation in visual pathway anatomy was found in the sighted and the blind. Anatomical changes within these clusters were graded by the timing of onset of blindness, with those subjects with a post-natal onset of blindness having alterations in brain anatomy that were intermediate to those seen in the sighted and congenitally blind. Many of the blind and sighted subjects also contributed functional MRI measures of cross-modal responses within visual cortex, and a diffusion tensor imaging measure of fractional anisotropy within the optic radiations and the splenium of the corpus callosum. We again found group differences between the blind and sighted in these measures. The previously identified clusters of anatomical variation were also found to be differentially related to these additional measures: across subjects, V1 cortical thickness was related to cross-modal activation, and the volume of the optic chiasm and lateral geniculate was related to fractional anisotropy in the visual pathway. Our findings show that several of the structural and functional effects of blindness may be reduced to a smaller set of dimensions. It also seems that the changes in the brain that accompany blindness are on a continuum with normal variation found in the sighted. PMID:27812129

Modelling the line-of-sight contribution in substructure lensing

NASA Astrophysics Data System (ADS)

Despali, Giulia; Vegetti, Simona; White, Simon D. M.; Giocoli, Carlo; van den Bosch, Frank C.

2018-04-01

We investigate how Einstein rings and magnified arcs are affected by small-mass dark-matter haloes placed along the line of sight to gravitational lens systems. By comparing the gravitational signature of line-of-sight haloes with that of substructures within the lensing galaxy, we derive a mass-redshift relation that allows us to rescale the detection threshold (i.e. lowest detectable mass) for substructures to a detection threshold for line-of-sight haloes at any redshift. We then quantify the line-of-sight contribution to the total number density of low-mass objects that can be detected through strong gravitational lensing. Finally, we assess the degeneracy between substructures and line-of-sight haloes of different mass and redshift to provide a statistical interpretation of current and future detections, with the aim of distinguishing between cold dark matter and warm dark matter. We find that line-of-sight haloes statistically dominate with respect to substructures, by an amount that strongly depends on the source and lens redshifts, and on the chosen dark-matter model. Substructures represent about 30 percent of the total number of perturbers for low lens and source redshifts (as for the SLACS lenses), but less than 10 per cent for high-redshift systems. We also find that for data with high enough signal-to-noise ratio and angular resolution, the non-linear effects arising from a double-lens-plane configuration are such that one is able to observationally recover the line-of-sight halo redshift with an absolute error precision of 0.15 at the 68 per cent confidence level.

InSight Atlas V ISA-ASA Transport

NASA Image and Video Library

2018-03-05

At Vandenberg Air Force Base in California, the aft stub adapter (ASA) and interstage adapter (ISA) for a United Launch Alliance (ULA) Atlas V rocket is prepared for transport from Building 7525 to Space Launch Complex 3. The launch vehicle will send NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft to land on Mars. InSight is the first mission to explore the Red Planet's deep interior. InSight is scheduled for liftoff May 5, 2018. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. InSight will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the InSight mission for the agency’s Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by its Marshall Space Flight Center in Huntsville, Alabama. The spacecraft, including cruise stage and lander, was built and tested by Lockheed Martin Space in Denver. Several European partners, including France's space agency, the Centre National d'Étude Spatiales, and the German Aerospace Center, are supporting the mission. United Launch Alliance of Centennial, Colorado, is providing the Atlas V launch service. NASA’s Launch Services Program, based at its Kennedy Space Center in Florida, is responsible for launch management.

InSight Atlas V ISA-ASA Lift and Mate

NASA Image and Video Library

2018-03-05

At Space Launch Complex 3 at Vandenberg Air Force Base in California, technicians and engineers mate the aft stub adapter (ASA) and interstage adapter (ISA) for a United Launch Alliance (ULA) Atlas V to a Centaur upper stage. The launch vehicle will send NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft to land on Mars. InSight is the first mission to explore the Red Planet's deep interior. InSight is scheduled for liftoff May 5, 2018. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. InSight will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the InSight mission for the agency’s Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by its Marshall Space Flight Center in Huntsville, Alabama. The spacecraft, including cruise stage and lander, was built and tested by Lockheed Martin Space in Denver. Several European partners, including France's space agency, the Centre National d'Étude Spatiales, and the German Aerospace Center, are supporting the mission. United Launch Alliance of Centennial, Colorado, is providing the Atlas V launch service. NASA’s Launch Services Program, based at its Kennedy Space Center in Florida, is responsible for launch management.

InSight Atlas V ISA-ASA Transport

NASA Image and Video Library

2018-03-05

At Space Launch Complex 3 at Vandenberg Air Force Base in California, the aft stub adapter (ASA) and interstage adapter (ISA) for a United Launch Alliance (ULA) Atlas V are lifted by crane for mating atop a Centaur upper stage. The launch vehicle will send NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft to land on Mars. InSight is the first mission to explore the Red Planet's deep interior. InSight is scheduled for liftoff May 5, 2018. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. InSight will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the InSight mission for the agency’s Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by its Marshall Space Flight Center in Huntsville, Alabama. The spacecraft, including cruise stage and lander, was built and tested by Lockheed Martin Space in Denver. Several European partners, including France's space agency, the Centre National d'Étude Spatiales, and the German Aerospace Center, are supporting the mission. United Launch Alliance of Centennial, Colorado, is providing the Atlas V launch service. NASA’s Launch Services Program, based at its Kennedy Space Center in Florida, is responsible for launch management.

InSight Atlas V ISA-ASA Lift and Mate

NASA Image and Video Library

2018-03-05

At Space Launch Complex 3 at Vandenberg Air Force Base in California, a technician assists as the aft stub adapter (ASA) and interstage adapter (ISA) for a United Launch Alliance (ULA) Atlas V is lifted by crane for mating atop a Centaur upper stage. The launch vehicle will send NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft to land on Mars. InSight is the first mission to explore the Red Planet's deep interior. InSight is scheduled for liftoff May 5, 2018. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. InSight will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the InSight mission for the agency’s Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by its Marshall Space Flight Center in Huntsville, Alabama. The spacecraft, including cruise stage and lander, was built and tested by Lockheed Martin Space in Denver. Several European partners, including France's space agency, the Centre National d'Étude Spatiales, and the German Aerospace Center, are supporting the mission. United Launch Alliance of Centennial, Colorado, is providing the Atlas V launch service. NASA’s Launch Services Program, based at its Kennedy Space Center in Florida, is responsible for launch management.

Information Transfer Problems of the Partially Sighted: Recent Results and Project Summary.

ERIC Educational Resources Information Center

Genensky, S. M.; And Others

The fourth in a series of Rand reports on information transfer problems of the partially sighted reviews earlier reports and describes an experimental secretarial closed circuit TV (CCTV) system which enables the partially sighted to type from a printed or handwritten manuscript. Discussed are experiments using a pseudocolor system to determine…

Problem Behavior and Developmental Tasks in Adolescents with Visual Impairment and Sighted Peers

ERIC Educational Resources Information Center

Pfeiffer, Jens P.; Pinquart, Martin

2013-01-01

This longitudinal study analyzed associations of problem behavior with the attainment of developmental tasks in 133 adolescents with visual impairment and 449 sighted peers. Higher levels of initial problem behavior predicted less progress in the attainment of developmental tasks at the one-year follow-up only in sighted adolescents. This…

Behaviors of Sighted Individuals Perceived by Blind Persons as Hindrances to Self-Reliance in Blind Persons.

ERIC Educational Resources Information Center

Rickelman, Bonnie L.; Blaylock, Jerry N.

1983-01-01

Situations in which sighted people behaved inappropiately toward blind individuals were recalled by 60 blind subjects, who described their reactions and feelings and offered suggestions for sighted people. A lack of knowledge and understanding of the skills, abilities, and feelings of visually impaired individuals were revealed. (SEW)

InSight Launch

NASA Image and Video Library

2018-05-05

The NASA InSight spacecraft launches onboard a United Launch Alliance Atlas-V rocket, Saturday, May 5, 2018, from Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

The Effect of Key on Vocal Sight-Reading Achievement

ERIC Educational Resources Information Center

Henry, Michele L.

2013-01-01

At its most basic level, sight-reading can be defined as the production of accurate pitch and rhythm from a previously unseen musical score. For vocalists, sight-reading principally involves the production of pitches by determining their relationship within a tonal framework. The ability to mentally conceive tonal function and convert it into…

Vocal Sight-Reading Assessment: Technological Advances, Student Perceptions, and Instructional Implications

ERIC Educational Resources Information Center

Henry, Michele

2015-01-01

This study investigated choral singers' comfort level using computer technology for vocal sight-reading assessment. High school choral singers (N = 138) attending a summer music camp completed a computer-based sight-reading assessment and accompanying pre- and posttest surveys on their musical backgrounds and perceptions about technology. A large…

Evaluating New Approaches to Teaching of Sight-Reading Skills to Advanced Pianists

ERIC Educational Resources Information Center

Zhukov, Katie

2014-01-01

This paper evaluates three teaching approaches to improving sight-reading skills against a control in a large-scale study of advanced pianists. One hundred pianists in four equal groups participated in newly developed training programmes (accompanying, rhythm, musical style and control), with pre- and post-sight-reading tests analysed using…

The Relationship between Aerobic Capacity and Physical Activity in Blind and Sighted Adolescents.

ERIC Educational Resources Information Center

Kobberling, G.; And Others

1991-01-01

This study investigated the relationship between habitual physical activity and aerobic capacity in 30 blind and 30 sighted adolescents. Both physical activity and maximal oxygen consumption were significantly higher among the sighted adolescents. A minimum of 30 minutes of daily activity at a minimal oxygen consumption of 8 METs (resting…

OnSight: Multi-platform Visualization of the Surface of Mars

NASA Astrophysics Data System (ADS)

Abercrombie, S. P.; Menzies, A.; Winter, A.; Clausen, M.; Duran, B.; Jorritsma, M.; Goddard, C.; Lidawer, A.

2017-12-01

A key challenge of planetary geology is to develop an understanding of an environment that humans cannot (yet) visit. Instead, scientists rely on visualizations created from images sent back by robotic explorers, such as the Curiosity Mars rover. OnSight is a multi-platform visualization tool that helps scientists and engineers to visualize the surface of Mars. Terrain visualization allows scientists to understand the scale and geometric relationships of the environment around the Curiosity rover, both for scientific understanding and for tactical consideration in safely operating the rover. OnSight includes a web-based 2D/3D visualization tool, as well as an immersive mixed reality visualization. In addition, OnSight offers a novel feature for communication among the science team. Using the multiuser feature of OnSight, scientists can meet virtually on Mars, to discuss geology in a shared spatial context. Combining web-based visualization with immersive visualization allows OnSight to leverage strengths of both platforms. This project demonstrates how 3D visualization can be adapted to either an immersive environment or a computer screen, and will discuss advantages and disadvantages of both platforms.

Looking at eye dominance from a different angle: is sighting strength related to hand preference?

PubMed

Carey, David P; Hutchinson, Claire V

2013-10-01

Sighting dominance (the behavioural preference for one eye over the other under monocular viewing conditions) has traditionally been thought of as a robust individual trait. However, Khan and Crawford (2001) have shown that, under certain viewing conditions, eye preference reverses as a function of horizontal gaze angle. Remarkably, the reversal of sighting from one eye to the other depends on which hand is used to reach out and grasp the target. Their procedure provides an ideal way to measure the strength of monocular preference for sighting, which may be related to other indicators of hemispheric specialisation for speech, language and motor function. Therefore, we hypothesised that individuals with consistent side preferences (e.g., right hand, right eye) should have more robust sighting dominance than those with crossed lateral preferences. To test this idea, we compared strength of eye dominance in individuals who are consistently right or left sided for hand and foot preference with those who are not. We also modified their procedure in order to minimise a potential image size confound, suggested by Banks et al. (2004) as an explanation of Khan and Crawford's results. We found that the sighting dominance switch occurred at similar eccentricities when we controlled for effects of hand occlusion and target size differences. We also found that sighting dominance thresholds change predictably with the hand used. However, we found no evidence for relationships between strength of hand preference as assessed by questionnaire or by pegboard performance and strength of sighting dominance. Similarly, participants with consistent hand and foot preferences did not show stronger eye preference as assessed using the Khan and Crawford procedure. These data are discussed in terms of indirect relationships between sighting dominance, hand preference and cerebral specialisation for language and motor control. Copyright © 2013 Elsevier Ltd. All rights reserved.

Trends in anecdotal fox sightings in Tasmania accounted for by psychological factors.

PubMed

Marks, Clive A; Clark, Malcolm; Obendorf, David; Hall, Graham P; Soares, Inês; Pereira, Filipe

2017-12-01

There has been little evaluation of anecdotal sightings as a means to confirm new incursions of invasive species. This paper explores the potential for equivocal information communicated by the media to account for patterns of anecdotal reports. In 2001, it was widely reported that red foxes (Vulpes vulpes) had been deliberately released in the island state of Tasmania (Australia), although this claim was later revealed to be baseless. Regardless, by 2013 a total of 3153 anecdotal fox sightings had been reported by members of the public, which implied their distribution was wide. For each month in 2001-2003, we defined a monthly media index (MMI) of fox-related media coverage, an index of their relative seasonal abundance (abundance), and a factor denoting claims of fox evidence (claimed evidence) regardless of its evidentiary quality. We fitted a generalized linear model with Poisson error for monthly totals of anecdotal sightings with factors of year and claimed evidence and covariates of MMI, abundance, and hours of darkness. The collective effect of psychological factors (MMI, claimed evidence, and year) relative to biophysical factors (photoperiod and abundance) was highly significant (χ 2 = 122.1, df = 6, p < 0.0001), whereas anticipated changes in abundance had no significant influence on reported sightings (p = 0.15). An annual index of fox media from 2001 to 2010 was strongly associated with the yearly tally of anecdotal sightings (p = 0.018). The odds ratio of sightings ranked as reliable by the fox eradication program in any year decreased exponentially at a rate of 0.00643 as the total number of sightings increased (p < 0.0001) and was indicative of an observer-expectancy bias. Our results suggest anecdotal sightings are highly susceptible to cognitive biases and when used to qualify and quantify species presence can contribute to flawed risk assessments. © 2017 Society for Conservation Biology.

On the orbits that generate the X-shape in the Milky Way bulge

NASA Astrophysics Data System (ADS)

Abbott, Caleb G.; Valluri, Monica; Shen, Juntai; Debattista, Victor P.

2017-09-01

The Milky Way (MW) bulge shows a boxy/peanut or X-shaped bulge (hereafter BP/X) when viewed in infrared or microwave bands. We examine orbits in an N-body model of a barred disc galaxy that is scaled to match the kinematics of the MW bulge. We generate maps of projected stellar surface density, unsharp masked images, 3D excess-mass distributions (showing mass outside ellipsoids), line-of-sight number count distributions, and 2D line-of-sight kinematics for the simulation as well as co-added orbit families, in order to identify the orbits primarily responsible for the BP/X shape. We estimate that between 19 and 23 per cent of the mass of the bar in this model is associated with the BP/X shape and that the majority of bar orbits contribute to this shape that is clearly seen in projected surface density maps and 3D excess mass for non-resonant box orbits, 'banana' orbits, 'fish/pretzel' orbits and 'brezel' orbits. Although only the latter two families (comprising 7.5 per cent of the total mass) show a distinct X-shape in unsharp masked images, we find that nearly all bar orbit families contribute some mass to the 3D BP/X-shape. All co-added orbit families show a bifurcation in stellar number count distribution with distance that resembles the bifurcation observed in red clump stars in the MW. However, only the box orbit family shows an increasing separation of peaks with increasing galactic latitude |b|, similar to that observed. Our analysis suggests that no single orbit family fully explains all the observed features associated with the MW's BP/X-shaped bulge, but collectively the non-resonant boxes and various resonant boxlet orbits contribute at different distances from the centre to produce this feature. We propose that since box orbits (which are the dominant population in bars) have three incommensurable orbital fundamental frequencies, their 3D shapes are highly flexible and, like Lissajous figures, this family of orbits is most easily able to adapt to evolution in the shape of the underlying potential.

Establishing the fundamentals for an elephant early warning and monitoring system.

PubMed

Zeppelzauer, Matthias; Stoeger, Angela S

2015-09-04

The decline of habitat for elephants due to expanding human activity is a serious conservation problem. This has continuously escalated the human-elephant conflict in Africa and Asia. Elephants make extensive use of powerful infrasonic calls (rumbles) that travel distances of up to several kilometers. This makes elephants well-suited for acoustic monitoring because it enables detecting elephants even if they are out of sight. In sight, their distinct visual appearance makes them a good candidate for visual monitoring. We provide an integrated overview of our interdisciplinary project that established the scientific fundamentals for a future early warning and monitoring system for humans who regularly experience serious conflict with elephants. We first draw the big picture of an early warning and monitoring system, then review the developed solutions for automatic acoustic and visual detection, discuss specific challenges and present open future work necessary to build a robust and reliable early warning and monitoring system that is able to operate in situ. We present a method for the automated detection of elephant rumbles that is robust to the diverse noise sources present in situ. We evaluated the method on an extensive set of audio data recorded under natural field conditions. Results show that the proposed method outperforms existing approaches and accurately detects elephant rumbles. Our visual detection method shows that tracking elephants in wildlife videos (of different sizes and postures) is feasible and particularly robust at near distances. From our project results we draw a number of conclusions that are discussed and summarized. We clearly identified the most critical challenges and necessary improvements of the proposed detection methods and conclude that our findings have the potential to form the basis for a future automated early warning system for elephants. We discuss challenges that need to be solved and summarize open topics in the context of a future early warning and monitoring system. We conclude that a long-term evaluation of the presented methods in situ using real-time prototypes is the most important next step to transfer the developed methods into practical implementation.

Some like it hot: Repeat migration and residency of whale sharks within an extreme natural environment.

PubMed

Robinson, David P; Jaidah, Mohammed Y; Bach, Steffen S; Rohner, Christoph A; Jabado, Rima W; Ormond, Rupert; Pierce, Simon J

2017-01-01

The Arabian Gulf is the warmest sea in the world and is host to a globally significant population of the whale shark Rhincodon typus. To investigate regional whale shark behaviour and movements, 59 satellite-linked tags were deployed on whale sharks in the Al Shaheen area off Qatar from 2011-14. Four different models of tag were used throughout the study, each model able to collect differing data or quantities of data. Retention varied from one to 227 days. While all tagged sharks crossed international maritime boundaries, they typically stayed within the Arabian Gulf. Only nine sharks dispersed through the narrow Strait of Hormuz into the Gulf of Oman. Most sharks stayed close to known or suspected feeding aggregation sites over summer months, but dispersed throughout the Arabian Gulf in winter. Sharks rarely ventured into shallow areas (<40 m depth). A single, presumably pregnant female shark was the sole animal to disperse a long distance, crossing five international maritime boundaries in 37 days before the tag detached at a distance of approximately 2644 km from the tagging site, close to the Yemeni-Somali border. No clear space-use differentiation was evident between years, for sharks of different sizes, or between sexes. Whale sharks spent the most time (~66%) in temperatures of 24-30°C and in shallow waters <100 m depth (~60%). Sharks spent relatively more time in cooler (X2 = 121.692; p<0.05) and deeper (X2 = 46.402; p<0.05) water at night. Sharks rarely made dives deeper than 100 m, reflecting the bathymetric constraints of the Gulf environment. Kernel density analysis demonstrated that the tagging site at Al Shaheen was the regional hotspot for these sharks, and revealed a probable secondary aggregation site for whale sharks in nearby Saudi Arabian waters. Analysis of visual re-sightings data of tagged sharks revealed that 58% of tagged individuals were re-sighted back in Al Shaheen over the course of this study, with 40% recorded back at Al Shaheen in the year following their initial identification. Two sharks were confirmed to return to Al Shaheen in each of the five years of study.

The effects of marine traffic on the behaviour of Black Sea harbour porpoises (Phocoena phocoena relicta) within the Istanbul Strait, Turkey.

PubMed

Akkaya Bas, Aylin; Christiansen, Fredrik; Amaha Öztürk, Ayaka; Öztürk, Bayram; McIntosh, Caley

2017-01-01

Marine traffic is threatening cetaceans on a local and global scale. The Istanbul Strait is one of the busiest waterways, with up to 2,500 vessels present daily. This is the first study to assess the magnitude of short- and long-term behavioural changes of the endangered Black Sea harbour porpoises (Phocoena phocoena relicta) in the presence of marine vessels within the Istanbul Strait. Markov chains were used to investigate the effect of vessel presence on the transition probability between behavioural states (diving, surface-feeding and travelling), and to quantify the effect on the behavioural budget and bout length (duration of time spent in a given state) of porpoises. Further, the changes on swimming directions of porpoises in relation to vessel speed and distance was investigated using generalized linear models. In vessel presence, porpoises were less likely to remain in a given behavioural state and instead more likely to switch to another state. Because of this, the bout length of all three behavioural states decreased significantly in the presence of vessels. The vessel effect was sufficiently large to alter the behavioural budget, with surface-feeding decreasing significantly in the presence of vessels. However, when taking into account the proportion of time that porpoises were exposed to vessels (i.e. 50%), the measured effect size was not large enough to significantly alter the animals' cumulative (diurnal) behavioural budget. Additionally, vessel speed and distance had a significant effect on the probability of porpoises showing a response in their swimming directions. The southern and middle sections of the Istanbul Strait, which have the heaviest marine traffic pressure, had the lowest porpoise sightings throughout the year. Conversely, northern sections that were exposed to a lesser degree of marine traffic hold the highest porpoise sightings. The effect shown in this study in combination with increasing human impacts within the northern sections should be considered carefully and species-specific conservation actions, including establishment of protected areas, should be put in place to prevent the long-term consequences of marine traffic on the Black Sea harbour porpoise population.

The effects of marine traffic on the behaviour of Black Sea harbour porpoises (Phocoena phocoena relicta) within the Istanbul Strait, Turkey

PubMed Central

Christiansen, Fredrik; Amaha Öztürk, Ayaka; Öztürk, Bayram; McIntosh, Caley

2017-01-01

Marine traffic is threatening cetaceans on a local and global scale. The Istanbul Strait is one of the busiest waterways, with up to 2,500 vessels present daily. This is the first study to assess the magnitude of short- and long-term behavioural changes of the endangered Black Sea harbour porpoises (Phocoena phocoena relicta) in the presence of marine vessels within the Istanbul Strait. Markov chains were used to investigate the effect of vessel presence on the transition probability between behavioural states (diving, surface-feeding and travelling), and to quantify the effect on the behavioural budget and bout length (duration of time spent in a given state) of porpoises. Further, the changes on swimming directions of porpoises in relation to vessel speed and distance was investigated using generalized linear models. In vessel presence, porpoises were less likely to remain in a given behavioural state and instead more likely to switch to another state. Because of this, the bout length of all three behavioural states decreased significantly in the presence of vessels. The vessel effect was sufficiently large to alter the behavioural budget, with surface-feeding decreasing significantly in the presence of vessels. However, when taking into account the proportion of time that porpoises were exposed to vessels (i.e. 50%), the measured effect size was not large enough to significantly alter the animals’ cumulative (diurnal) behavioural budget. Additionally, vessel speed and distance had a significant effect on the probability of porpoises showing a response in their swimming directions. The southern and middle sections of the Istanbul Strait, which have the heaviest marine traffic pressure, had the lowest porpoise sightings throughout the year. Conversely, northern sections that were exposed to a lesser degree of marine traffic hold the highest porpoise sightings. The effect shown in this study in combination with increasing human impacts within the northern sections should be considered carefully and species-specific conservation actions, including establishment of protected areas, should be put in place to prevent the long-term consequences of marine traffic on the Black Sea harbour porpoise population. PMID:28296899

Anatomy of the AGN in NGC 5548. IX. Photoionized emission features in the soft X-ray spectra

NASA Astrophysics Data System (ADS)

Mao, Junjie; Kaastra, J. S.; Mehdipour, M.; Gu, Liyi; Costantini, E.; Kriss, G. A.; Bianchi, S.; Branduardi-Raymont, G.; Behar, E.; Di Gesu, L.; Ponti, G.; Petrucci, P.-O.; Ebrero, J.

2018-04-01

The X-ray narrow emission line region (NELR) of the archetypal Seyfert 1 galaxy NGC 5548 has been interpreted as a single-phase photoionized plasma that is absorbed by some of the warm absorber components. This scenario requires those overlaying warm absorber components to have larger distance (to the central engine) than the X-ray NELR, which is not fully consistent with the distance estimates found in the literature. Therefore, we reanalyze the high-resolution spectra obtained in 2013-2014 with the Reflection Grating Spectrometer (RGS) aboard XMM-Newton to provide an alternative interpretation of the X-ray narrow emission features. We find that the X-ray narrow emission features in NGC 5548 can be described by a two-phase photoionized plasma with different ionization parameters (logξ = 1.3 and 0.1) and kinematics (vout = -50 and -400 km s-1), and no further absorption by the warm absorber components. The X-ray and optical NELR might be the same multi-phase photoionized plasma. Both X-ray and optical NELR have comparable distances, asymmetric line profiles, and the underlying photoionized plasma is turbulent and compact in size. The X-ray NELR is not the counterpart of the UV/X-ray absorber outside the line of sight because their distances and kinematics are not consistent. In addition, X-ray broad emission features that we find in the spectrum can be accounted for by a third photoionized emission component. The RGS spectrum obtained in 2016 is analyzed as well, where the luminosity of most prominent emission lines (the O VII forbidden line and O VIII Lyα line) are the same (at a 1σ confidence level) as in 2013-2014.

Propagation and perception of bioluminescence: factors affecting counterillumination as a cryptic strategy.

PubMed

Johnsen, Sönke; Widder, Edith A; Mobley, Curtis D

2004-08-01

Many deep-sea species, particularly crustaceans, cephalopods, and fish, use photophores to illuminate their ventral surfaces and thus disguise their silhouettes from predators viewing them from below. This strategy has several potential limitations, two of which are examined here. First, a predator with acute vision may be able to detect the individual photophores on the ventral surface. Second, a predator may be able to detect any mismatch between the spectrum of the bioluminescence and that of the background light. The first limitation was examined by modeling the perceived images of the counterillumination of the squid Abralia veranyi and the myctophid fish Ceratoscopelus maderensis as a function of the distance and visual acuity of the viewer. The second limitation was addressed by measuring downwelling irradiance under moonlight and starlight and then modeling underwater spectra. Four water types were examined: coastal water at a depth of 5 m and oceanic water at 5, 210, and 800 m. The appearance of the counterillumination was more affected by the visual acuity of the viewer than by the clarity of the water, even at relatively large distances. Species with high visual acuity (0.11 degrees resolution) were able to distinguish the individual photophores of some counterilluminating signals at distances of several meters, thus breaking the camouflage. Depth and the presence or absence of moonlight strongly affected the spectrum of the background light, particularly near the surface. The increased variability near the surface was partially offset by the higher contrast attenuation at shallow depths, which reduced the sighting distance of mismatches. This research has implications for the study of spatial resolution, contrast sensitivity, and color discrimination in deep-sea visual systems.

Prevalence of cigarette advertising and other promotional strategies at the point of sale in St Louis, Missouri: analysis by store type and distance from a school.

PubMed

Barnoya, Joaquin; Colditz, Graham; Moreland-Russell, Sarah; Cyr, Julianne; Snider, Doneisha; Schootman, Mario

2014-04-17

Point-of-sale advertising provides an opportunity for the tobacco industry to communicate with current and potential smokers. The US Family Smoking Prevention and Tobacco Control Act allows states to implement policies requiring that tobacco products be placed out of sight, and the Food and Drug Administration is considering banning point-of-sale advertising within 1,000 feet of schools. Our objective was to compare cigarette point-of-sale advertising near schools with grades prekindergarten through 12 and by store type. All registered cigarette retailers (n = 1,229) and schools (n = 581) in the city of St Louis and St Louis County were geocoded and mapped by using ArcGIS. Retailers were divided into 2 groups, those within 1,000 feet and those within 1,001 to 2,000 feet of a school; 200 retailers from each group were randomly selected. We assessed tobacco interior and exterior advertising, brands advertised, discounts, gifts with purchase, "no sales to minors" signage, and cigarette functional items (eg, advertising on shopping baskets). Analyses were done by distance from a school and store type. We analyzed 340 retailers. Most retailers within 1,000 feet (91.2%) and from 1,001 to 2,000 feet (94.2%) of a school displayed cigarette advertising (P = .20). Convenience stores had the highest number of interior ads. In multivariable models, distance from school explained 0.2% of the variance in total advertising. Cigarette point-of-sale advertising is highly prevalent in St Louis within 1,000 feet of schools. A ban based on distance from a school might decrease advertising exposure, but its effect on smoking prevalence is yet to be determined because advertising farther from schools would still prevail.

Investigation of the flow structure in thin polymer films using 3D µPTV enhanced by GPU

NASA Astrophysics Data System (ADS)

Cavadini, Philipp; Weinhold, Hannes; Tönsmann, Max; Chilingaryan, Suren; Kopmann, Andreas; Lewkowicz, Alexander; Miao, Chuan; Scharfer, Philip; Schabel, Wilhelm

2018-04-01

To understand the effects of inhomogeneous drying on the quality of polymer coatings, an experimental setup to resolve the occurring flow field throughout the drying film has been developed. Deconvolution microscopy is used to analyze the flow field in 3D and time. Since the dimension of the spatial component in the direction of the line-of-sight is limited compared to the lateral components, a multi-focal approach is used. Here, the beam of light is equally distributed on up to five cameras using cubic beam splitters. Adding a meniscus lens between each pair of camera and beam splitter and setting different distances between each camera and its meniscus lens creates multi-focality and allows one to increase the depth of the observed volume. Resolving the spatial component in the line-of-sight direction is based on analyzing the point spread function. The analysis of the PSF is computational expensive and introduces a high complexity compared to traditional particle image velocimetry approaches. A new algorithm tailored to the parallel computing architecture of recent graphics processing units has been developed. The algorithm is able to process typical images in less than a second and has further potential to realize online analysis in the future. As a prove of principle, the flow fields occurring in thin polymer solutions drying at ambient conditions and at boundary conditions that force inhomogeneous drying are presented.

Shielding Design for the South Pole nToF Diagnostic at the NIF

NASA Astrophysics Data System (ADS)

Khater, Hesham; Sitaraman, Shiva; Hall, James; Hatarik, Robert; Caggiano, Joseph; Waltz, Cory

2017-09-01

Neutron time of flight (nToF) detectors are fielded at the National Ignition Facility (NIF) to measure neutron yield, ion temperature, and downscattering in the cold fuel for D-T implosions. Anisotropically assembled cold fuel may generate different nToF data when measured by detectors located at the Target Chamber equator and poles. A collimated nToF line of sight has been fielded near the Target Chamber South Pole (SP) to examine any possible anisotropy in the cold fuel. The SP nToF detector is located in the lowest floor level of the NIF's Target Bay and at a distance of 18 m from the Target Chamber Center. The detector utilizes a solid bibenzyl scintillator and four photomultiplier tubes. The line of sight includes a port collimator that is attached to the Target Chamber and a bore hole collimator in the concrete floor above the detector. In addition, a beam line get lost hole is constructed in the Target Bay floor to minimize the backscattered radiation at the detector location. Initial measurements indicated the need for installation of additional shielding to eliminate gamma background during the period before arrival of the 14.1 MeV neutrons to the detector. A set of MCNP Monte Carlo simulations with the full Target Bay model were conducted to provide an estimate of the expected neutron and gamma backgrounds during D-T shots. A new shielding scheme is designed to reduce the gamma background by an order of magnitude.

Creating cometary models using ancient Chinese data

NASA Astrophysics Data System (ADS)

Yeomans, D. K.

For more than two millennia, Chinese court astronomers maintained a rather comprehensive record of cometary sightings. Owing to the significance of comets as portents for the reigning emperor, early sky watchers from China (as well as their counterparts from Korea and Japan) carefully noted each cometary apparition for the purpose of astrological predictions. The dates and corresponding celestial locations and motions were usually recorded and in some cases, the colors, coma sizes, and tail lengths were also noted. These ancient observations represent the only source of information available for modeling the long-term behavior of periodic comets. For comets Halley and Swift-Tuttle, Chinese records have been identified as far back as 240 B.C. and 69 B.C. respectively and these data have been used to define their long-term motions. As a result, heliocentric and geocentric distances for each Chinese sighting of these two comets can be computed and estimates can be made for each comet's intrinsic brightness at various observed returns. Although the earliest identified apparition of comet Tempel-Tuttle is A.D. 1366, the associated Leonid meteor showers were noted back to at least A.D. 902. The Leonid meteor stream is young in the sense that outstanding meteor displays occur only near the time of the parent comet's perihelion passages. The ancient Chinese records of the Leonid meteor showers and storms have been used to map the particle distribution around the parent comet and this information was used to guide predictions for the 1998-1999 Leonid meteor showers.

Combined hostile fire and optics detection

NASA Astrophysics Data System (ADS)

Brännlund, Carl; Tidström, Jonas; Henriksson, Markus; Sjöqvist, Lars

2013-10-01

Snipers and other optically guided weapon systems are serious threats in military operations. We have studied a SWIR (Short Wave Infrared) camera-based system with capability to detect and locate snipers both before and after shot over a large field-of-view. The high frame rate SWIR-camera allows resolution of the temporal profile of muzzle flashes which is the infrared signature associated with the ejection of the bullet from the rifle. The capability to detect and discriminate sniper muzzle flashes with this system has been verified by FOI in earlier studies. In this work we have extended the system by adding a laser channel for optics detection. A laser diode with slit-shaped beam profile is scanned over the camera field-of-view to detect retro reflection from optical sights. The optics detection system has been tested at various distances up to 1.15 km showing the feasibility to detect rifle scopes in full daylight. The high speed camera gives the possibility to discriminate false alarms by analyzing the temporal data. The intensity variation, caused by atmospheric turbulence, enables discrimination of small sights from larger reflectors due to aperture averaging, although the targets only cover a single pixel. It is shown that optics detection can be integrated in combination with muzzle flash detection by adding a scanning rectangular laser slit. The overall optics detection capability by continuous surveillance of a relatively large field-of-view looks promising. This type of multifunctional system may become an important tool to detect snipers before and after shot.

How gravitational lensing helps γ-ray photons avoid γ – γ absorption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barnacka, Anna; Böttcher, Markus; Sushch, Iurii, E-mail: abarnacka@cfa.harvard.edu, E-mail: Markus.Bottcher@nwu.ac.za

2014-08-01

We investigate potential γ – γ absorption of γ-ray emission from blazars arising from inhomogeneities along the line of sight, beyond the diffuse Extragalactic Background Light (EBL). As plausible sources of excess γ – γ opacity, we consider (1) foreground galaxies, including cases in which this configuration leads to strong gravitational lensing, (2) individual stars within these foreground galaxies, and (3) individual stars within our own galaxy, which may act as lenses for microlensing events. We found that intervening galaxies close to the line of sight are unlikely to lead to significant excess γ – γ absorption. This opens upmore » the prospect of detecting lensed gamma-ray blazars at energies above 10 GeV with their gamma-ray spectra effectively only affected by the EBL. The most luminous stars located either in intervening galaxies or in our galaxy provide an environment in which these gamma-rays could, in principle, be significantly absorbed. However, despite a large microlensing probability due to stars located in intervening galaxies, γ-rays avoid absorption by being deflected by the gravitational potentials of such intervening stars to projected distances ({sup i}mpact parameters{sup )} where the resulting γ – γ opacities are negligible. Thus, neither of the intervening excess photon fields considered here, provide a substantial source of excess γ – γ opacity beyond the EBL, even in the case of very close alignments between the background blazar and a foreground star or galaxy.« less

C-17 Shipping InSight Mars Spacecraft to Vandenberg Air Force Base

NASA Image and Video Library

2018-02-28

A C-17 cargo aircraft carrying NASA's InSight spacecraft flew from Buckley Air Force Base, Denver, to Vandenberg Air Force Base, California, on February 28, 2018. The spacecraft was being shipped from Lockheed Martin Space, Denver, where InSight was built and tested. Its launch period opens May 5, 2018. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is the first mission dedicated to studying the deep interior of Mars. Its findings will advance understanding of the early history of all rocky planets, including Earth. https://photojournal.jpl.nasa.gov/catalog/PIA22251

Assessment of Re-sighting Rates of Previously Dart-Tagged False Killer Whales and Short-Finned Pilot Whales in Hawai’i: A Preliminary Report Taking into Account Re-sighting of Social Groups

DTIC Science & Technology

2011-10-14

For example, with southern resident killer whales , re-sighting a specific pod (or sub-pod) member is likely only if that pod (or sub-pod) has been...remaining four clusters are seen infrequently, a situation similar to pod-specific differences in sighting rates for northern resident killer whales (Ford...Satellite tracking reveals distinct movement patterns for Type B and Type C killer whales in the southern Ross Sea, Antarctica. Polar Biology 31:1461

Artist Rendition of InSight

NASA Image and Video Library

2012-08-20

Artist rendition of the InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) Lander. InSight is based on the proven Phoenix Mars spacecraft and lander design with state-of-the-art avionics from the Mars Reconnaissance Orbiter and Gravity Recovery and Interior Laboratory missions. Note: After thorough examination, NASA managers have decided to suspend the planned March 2016 launch of the Interior Exploration using Seismic Investigations Geodesy and Heat Transport (InSight) mission. The decision follows unsuccessful attempts to repair a leak in a section of the prime instrument in the science payload. http://photojournal.jpl.nasa.gov/catalog/PIA16079

InSight Spacecraft Uncrating, Removal from Container, Lift Heat

NASA Image and Video Library

2018-03-01

Inside the Astrotech processing facility at Vandenberg Air Force Base in California, technicians and engineers use a crane to move the heatshield for NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, spacecraft for further testing. InSight was developed and built by Lockheed-Martin Space Systems in Denver, Colorado, and is scheduled for liftoff is May 5, 2018. InSight is the first mission to land on Mars and explore the Red Planet's deep interior. It will investigate processes that shaped the rocky planets of the inner solar system including Earth.

InSight Media Day Preparation

NASA Image and Video Library

2018-04-05

NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, is in a clean room inside the Astrotech processing facility at Vandenberg Air Force Base in California. The spacecraft's protective heat shield is in view at right. InSight is scheduled for liftoff on a United Launch Alliance Atlas V rocket May 5, 2018. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. InSight will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the InSight mission for the agency’s Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by its Marshall Space Flight Center in Huntsville, Alabama. The spacecraft, including cruise stage and lander, was built and tested by Lockheed Martin Space in Denver. Several European partners, including France's space agency, the Centre National d'Étude Spatiales, and the German Aerospace Center, are supporting the mission. United Launch Alliance of Centennial, Colorado, is providing the Atlas V launch service. NASA’s Launch Services Program, based at its Kennedy Space Center in Florida, is responsible for launch management.

InSight Media Day Preparation

NASA Image and Video Library

2018-04-05

NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, at right, is in a clean room inside the Astrotech processing facility at Vandenberg Air Force Base in California. The spacecraft's protective heat shield is in view at left. InSight is scheduled for liftoff on a United Launch Alliance Atlas V rocket May 5, 2018. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. InSight will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the InSight mission for the agency’s Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by its Marshall Space Flight Center in Huntsville, Alabama. The spacecraft, including cruise stage and lander, was built and tested by Lockheed Martin Space in Denver. Several European partners, including France's space agency, the Centre National d'Étude Spatiales, and the German Aerospace Center, are supporting the mission. United Launch Alliance of Centennial, Colorado, is providing the Atlas V launch service. NASA’s Launch Services Program, based at its Kennedy Space Center in Florida, is responsible for launch management.

InSight Media Day Preparation

NASA Image and Video Library

2018-04-05

NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, is in a clean room inside the Astrotech processing facility at Vandenberg Air Force Base in California. The spacecraft's protective heat shield is in view at left. InSight is scheduled for liftoff on a United Launch Alliance Atlas V rocket May 5, 2018. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. InSight will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the InSight mission for the agency’s Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by its Marshall Space Flight Center in Huntsville, Alabama. The spacecraft, including cruise stage and lander, was built and tested by Lockheed Martin Space in Denver. Several European partners, including France's space agency, the Centre National d'Étude Spatiales, and the German Aerospace Center, are supporting the mission. United Launch Alliance of Centennial, Colorado, is providing the Atlas V launch service. NASA’s Launch Services Program, based at its Kennedy Space Center in Florida, is responsible for launch management.

Space-Time Localization of Plasma Turbulence Using Multiple Spacecraft Radio Links

NASA Technical Reports Server (NTRS)

Armstrong, John W.; Estabrook, Frank B.

2011-01-01

Space weather is described as the variability of solar wind plasma that can disturb satellites and systems and affect human space exploration. Accurate prediction requires information of the heliosphere inside the orbit of the Earth. However, for predictions using remote sensing, one needs not only plane-of-sky position but also range information the third spatial dimension to show the distance to the plasma disturbances and thus when they might propagate or co-rotate to create disturbances at the orbit of the Earth. Appropriately processed radio signals from spacecraft having communications lines-of-sight passing through the inner heliosphere can be used for this spacetime localization of plasma disturbances. The solar plasma has an electron density- and radio-wavelength-dependent index of refraction. An approximately monochromatic wave propagating through a thin layer of plasma turbulence causes a geometrical-optics phase shift proportional to the electron density at the point of passage, the radio wavelength, and the thickness of the layer. This phase shift is the same for a wave propagating either up or down through the layer at the point of passage. This attribute can be used for space-time localization of plasma irregularities. The transfer function of plasma irregularities to the observed time series depends on the Doppler tracking mode. When spacecraft observations are in the two-way mode (downlink radio signal phase-locked to an uplink radio transmission), plasma fluctuations have a two-pulse response in the Doppler. In the two-way mode, the Doppler time series y2(t) is the difference between the frequency of the downlink signal received and the frequency of a ground reference oscillator. A plasma blob localized at a distance x along the line of sight perturbs the phase on both the up and down link, giving rise to two events in the two-way tracking time series separated by a time lag depending the blob s distance from the Earth: T2-2x/c, where T2 is the two-way time-of-flight of radio waves to/from the spacecraft and c is the speed of light. In some tracking situations, more information is available. For example, with the 5-link Cassini radio system, the plasma contribution to the up and down links, y(sub up)(t) and y(sub dn)(t), can be computed separately. The times series y(sub up)(t) and y(sub dn)(t) respond to a localized plasma blob with one event in each time series. These events are also separated in time by T2-2x/c. By cross-correlating the up and down link Doppler time series, the time separation of the plasma events can be measured and hence the plasma blob s distance from the Earth determined. Since the plane-of-sky position is known, this technique allows localization of plasma events in time and three space dimensions.

A Comparative Study of the Manneristic Behaviour of Blind and Sighted Children. Research Series No. 1.

ERIC Educational Resources Information Center

Indian National Inst. for the Visually Handicapped, Dehra Dun.

Examination of the manneristic behavior (stereotyped or repetitive movement) of 542 blind and 365 sighted children was undertaken. Seventeen types of manneristic behavior were investigated, including head movement, eye poking and rubbing, body rocking, kicking, and posture distortion. Comparison of the behaviors observed in sighted and blind Ss…

Immediate Memory for Haptically-Examined Braille Symbols by Blind and Sighted Subjects.

ERIC Educational Resources Information Center

Newman, Slater E.; And Others

The paper reports on two experiments in Braille learning which compared blind and sighted subjects on the immediate recall of haptically-examined Braille symbols. In the first study, sighted subjects (N=64) haptically examined each of a set of Braille symbols with their preferred or nonpreferred hand and immediately recalled the symbol by drawing…

Knowledge of Dental Health and Oral Hygiene Practices of Taiwanese Visually Impaired and Sighted Students

ERIC Educational Resources Information Center

Chang, Chien-Huey Sophie; Shih, Yeng-Hung

2004-01-01

This study investigated the dental health knowledge and oral hygiene practices of 95 students with visual impairments and 286 sighted students in Taiwan. It found that the students with visual impairments were less knowledgeable about dental health and less frequently completed oral hygiene practices than did the sighted students.

Comparison of Environmental Interactions and Motor Activity of Visually Handicapped and Sighted Children.

ERIC Educational Resources Information Center

Schneekloth, Lynda H.; Day, Diane

The study compared the motor activities and environmental interactions of 36 sighted, partially sighted, and blind children (7 to 13 years old) during unstructured play. Objectives were to assess motor proficiency level; to establish frequency and kind of gross motor, manipulative self stimulation, and social/play behaviors; and to assess use of…

46 CFR 154.1320 - Sighting ports, tubular gauge glasses, and flat plate type gauge glasses.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Sighting ports, tubular gauge glasses, and flat plate type gauge glasses. 154.1320 Section 154.1320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... glasses, and flat plate type gauge glasses. (a) Cargo tanks may have sighting ports as a secondary means...

46 CFR 154.1320 - Sighting ports, tubular gauge glasses, and flat plate type gauge glasses.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Sighting ports, tubular gauge glasses, and flat plate type gauge glasses. 154.1320 Section 154.1320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... glasses, and flat plate type gauge glasses. (a) Cargo tanks may have sighting ports as a secondary means...

Can Pictures Promote the Acquisition of Sight-Word Reading? An Evaluation of Two Potential Instructional Strategies

ERIC Educational Resources Information Center

Richardson, Amy R.; Lerman, Dorothea C.; Nissen, Melissa A.; Luck, Kally M.; Neal, Ashley E.; Bao, Shimin; Tsami, Loukia

2017-01-01

Sight-word instruction can be a useful supplement to phonics-based methods under some circumstances. Nonetheless, few studies have evaluated the conditions under which pictures may be used successfully to teach sight-word reading. In this study, we extended prior research by examining two potential strategies for reducing the effects of…

Improving Sight-Singing Performance in the Choral Ensemble: The Effect of Individual Testing.

ERIC Educational Resources Information Center

Demorest, Steven M.

1998-01-01

Examines the effect of individual testing in conjunction with group instruction on 306 students' sight-singing skills from beginning and advanced choirs of six high schools in Washington State. Reports that individual testing was found to be an effective means of improving individual sight-singing performance in group instructional situations.…

Relationships among Music Sight-Reading and Technical Proficiency, Spatial Visualization, and Aural Discrimination

ERIC Educational Resources Information Center

Hayward, Carol M.; Gromko, Joyce Eastlund

2009-01-01

The purpose of this study was to examine predictors of music sight-reading ability. The authors hypothesized that speed and accuracy of music sight-reading would be predicted by a combination of aural pattern discrimination, spatial-temporal reasoning, and technical proficiency. Participants (N = 70) were wind players in concert bands at a…

A Nationwide Overview of Sight-Singing Requirements of Large-Group Choral Festivals

ERIC Educational Resources Information Center

Norris, Charles E.

2004-01-01

The purpose of this study was to examine sight-singing requirements at junior and senior high school large-group ratings-based choral festivals throughout the United States. Responses to the following questions were sought from each state: (1) Are there ratings-based large-group choral festivals? (2) Is sight-singing a requirement? (3) Are there…

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

The United Launch Alliance (ULA) Atlas-V rocket is seen with NASA's InSight spacecraft onboard, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

InSight Prelaunch

NASA Image and Video Library

2018-05-03

The United Launch Alliance (ULA) Atlas-V rocket is seen with NASA's InSight spacecraft onboard, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

NASA Chief Scientist Jim Green discusses NASA's InSight mission during a prelaunch media briefing, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

Sight Word and Phonics Training in Children with Dyslexia

ERIC Educational Resources Information Center

McArthur, Genevieve; Castles, Anne; Kohnen, Saskia; Larsen, Linda; Jones, Kristy; Anandakumar, Thushara; Banales, Erin

2015-01-01

The aims of this study were to (a) compare sight word training and phonics training in children with dyslexia, and (b) determine if different orders of sight word and phonics training have different effects on the reading skills of children with dyslexia. One group of children (n = 36) did 8 weeks of phonics training (reading via grapheme-phoneme…

A Comparison of Two Flashcard Interventions for Teaching Sight Words to Early Readers

ERIC Educational Resources Information Center

January, Stacy-Ann A.; Lovelace, Mary E.; Foster, Tori E.; Ardoin, Scott P.

2017-01-01

Strategic Incremental Rehearsal (SIR) is a recently developed flashcard intervention that blends Traditional Drill with Incremental Rehearsal (IR) for teaching sight words. The initial study evaluating SIR found it was more effective than IR for teaching sight words to first-grade students. However, that study failed to assess efficiency, which is…

The Effects of Technology on the Sight-Reading Achievement of Beginning Choir Students

ERIC Educational Resources Information Center

Petty, Colleen; Henry, Michele L.

2014-01-01

The ultimate goal for many choral directors is to develop independent musicians within the ensemble. The ability to sing a series of pitches and rhythms at first sight is widely understood to be a fundamental building block of independent musicianship. Yet sight-reading is not simply a holistic skill. There are separate components of…

Loneliness among Students with Blindness and Sighted Students in Jordan: A Brief Report

ERIC Educational Resources Information Center

Hadidi, Muna S.; Al Khateeb, Jamal M.

2013-01-01

This study investigated loneliness among students with blindness and those who are sighted in Jordan, and examined whether loneliness levels vary according to gender. Students included 90 students with blindness and 79 sighted students selected from high schools and universities in the capital city of Amman. The instrument used to collect…

A correlation between hard gamma-ray sources and cosmic voids along the line of sight

DOE PAGES

Furniss, A.; Sutter, P. M.; Primack, J. R.; ...

2014-11-25

We estimate the galaxy density along lines of sight to hard extragalactic gamma-ray sources by correlating source positions on the sky with a void catalog based on the Sloan Digital Sky Survey (SDSS). Extragalactic gamma-ray sources that are detected at very high energy (VHE; E > 100 GeV) or have been highlighted as VHE-emitting candidates in the Fermi Large Area Telescope hard source catalog (together referred to as “VHE-like” sources) are distributed along underdense lines of sight at the 2.4σ level. There is a less suggestive correlation for the Fermi hard source population (1.7σ). A correlation between 10-500 GeV fluxmore » and underdense fraction along the line of sight for VHE-like and Fermi hard sources is found at 2.4σ and 2.6σ, calculated from the Pearson correlation coefficients of r = 0.57 and 0.47, respectively. The preference for underdense sight lines is not displayed by gamma-ray emitting galaxies within the second Fermi catalog, containing sources detected above 100 MeV, or the SDSS DR7 quasar catalog. We investigate whether this marginal correlation might be a result of lower extragalactic background light (EBL) photon density within the underdense regions and find that, even in the most extreme case of a entirely underdense sight line, the EBL photon density is only 2% less than the nominal EBL density. Translating this into gamma-ray attenuation along the line of sight for a highly attenuated source with opacity τ(E, z) ~ 5, we estimate that the attentuation of gamma-rays decreases no more than 10%. This decrease, although non-neglible, is unable to account for the apparent hard source correlation with underdense lines of sight.« less

Large Interstellar Polarisation Survey. II. UV/optical study of cloud-to-cloud variations of dust in the diffuse ISM

NASA Astrophysics Data System (ADS)

Siebenmorgen, R.; Voshchinnikov, N. V.; Bagnulo, S.; Cox, N. L. J.; Cami, J.; Peest, C.

2018-03-01

It is well known that the dust properties of the diffuse interstellar medium exhibit variations towards different sight-lines on a large scale. We have investigated the variability of the dust characteristics on a small scale, and from cloud-to-cloud. We use low-resolution spectro-polarimetric data obtained in the context of the Large Interstellar Polarisation Survey (LIPS) towards 59 sight-lines in the Southern Hemisphere, and we fit these data using a dust model composed of silicate and carbon particles with sizes from the molecular to the sub-micrometre domain. Large (≥6 nm) silicates of prolate shape account for the observed polarisation. For 32 sight-lines we complement our data set with UVES archive high-resolution spectra, which enable us to establish the presence of single-cloud or multiple-clouds towards individual sight-lines. We find that the majority of these 35 sight-lines intersect two or more clouds, while eight of them are dominated by a single absorbing cloud. We confirm several correlations between extinction and parameters of the Serkowski law with dust parameters, but we also find previously undetected correlations between these parameters that are valid only in single-cloud sight-lines. We find that interstellar polarisation from multiple-clouds is smaller than from single-cloud sight-lines, showing that the presence of a second or more clouds depolarises the incoming radiation. We find large variations of the dust characteristics from cloud-to-cloud. However, when we average a sufficiently large number of clouds in single-cloud or multiple-cloud sight-lines, we always retrieve similar mean dust parameters. The typical dust abundances of the single-cloud cases are [C]/[H] = 92 ppm and [Si]/[H] = 20 ppm.

Accuracy of the Welch Allyn Suresight for measurement of magnitude of astigmatism in 3- to 7-year-old children

PubMed Central

Harvey, Erin M.; Dobson, Velma; Miller, Joseph M.; Clifford-Donaldson, Candice E.; Green, Tina K.; Messer, Dawn H.; Garvey, Katherine A.

2009-01-01

Purpose To evaluate the accuracy of the Welch Allyn SureSight in noncycloplegic measurements of astigmatism as compared to cycloplegic Retinomax K+ autorefractor measurements of astigmatism in children from a Native American population with a high prevalence of high astigmatism. Methods Data are reported for 825 3- to 7-year-old children with no ocular abnormalities. Each child had a Retinomax K+ cycloplegic measurement of right eye astigmatism with a confidence rating ≥8 and 3 attempts to obtain a SureSight measurement on the right eye. Results SureSight measurement success rates did not differ significantly across age or measurement confidence rating (<6 vs ≥6). Ninety-six percent of children had at least 1 measurement (any confidence), and 89% had at least 1 measurement with confidence at the manufacturer's recommended value (≥6). Overall, the SureSight tended to overestimate astigmatism. If the SureSight measurement had any dioptric value (0.00 D to 3.00 D), astigmatism of 2.00 D or less was likely to be present. If the SureSight showed astigmatism beyond the instrument's dioptric range (>3.00 D), Retinomax K+ measurements indicated that >2.00 D of astigmatism was present in 136 of 157 (86.6%). In cooperative children for whom the SureSight would not give a reading, 32 of 34 (94%) had >3.00 D of astigmatism. Conclusions The SureSight does not provide an accurate, quantitative measure of amount of astigmatism. However, it does allow accurate categorization of amount of astigmatism as ≤2.00 D, >2.00 D, or >3.00 D, and it has high measurement success rate in young children. PMID:19840726

Reading Embossed Capital Letters: An fMRI Study in Blind and Sighted Individuals

PubMed Central

Burton, H.; McLaren, D.G.; Sinclair, R.J.

2013-01-01

Reading Braille activates visual cortex in blind people [Burton et al., J Neurophysiol 2002;87: 589-611; Sadato et al., Nature 1996;380:526-528; Sadato et al., Brain 1998;121:1213-1229]. Because learning Braille requires extensive training, we had sighted and blind people read raised block capital letters to determine whether all groups engage visual cortex similarly when reading by touch. Letters were passively rubbed across the right index finger at 30 mm/s using an MR-compatible drum stimulator. Age-matched sighted, early blind (lost sight 0–5 years), and late blind (lost sight >5.5 years) volunteers performed three tasks: stating an identified letter, stating a verb containing an identified letter, and feeling a moving smooth surface. Responses were voiced immediately after the drum stopped moving across the fingertip. All groups showed increased activity in visual areas V1 and V2 during both letter identification tasks. Blind compared to sighted participants showed greater activation increases predominantly in the parafoveal-peripheral portions of visuotopic areas and posterior parts of BA 20 and 37. Sighted participants showed suppressed activity in most of the same areas except for small positive responses bilaterally in V1, left V5/MT+, and bilaterally in BA 37/20. Blind individuals showed suppression of the language areas in the frontal cortex, while sighted individuals showed slight positive responses. Early blind showed a more extensive distribution of activity in superior temporal sulcal multisensory areas. These results show cross-modal reorganization of visual cortex and altered response dynamics in nonvisual areas that plausibly reflect mechanisms for adaptive plasticity in blindness. PMID:16142777

Stellar Stream and Halo Structure in the Andromeda Galaxy from a Subaru/Hyper Suprime-Cam Survey

NASA Astrophysics Data System (ADS)

Komiyama, Yutaka; Chiba, Masashi; Tanaka, Mikito; Tanaka, Masayuki; Kirihara, Takanobu; Miki, Yohei; Mori, Masao; Lupton, Robert H.; Guhathakurta, Puragra; Kalirai, Jason S.; Gilbert, Karoline; Kirby, Evan; Lee, Myun Gyoon; Jang, In Sung; Sharma, Sanjib; Hayashi, Kohei

2018-01-01

We present wide and deep photometry of the northwestern part of the halo of the Andromeda galaxy (M31) using Hyper Suprime-Cam on the Subaru Telescope. The survey covers a 9.2 deg2 field in the g, i, and NB515 bands and shows a clear red giant branch (RGB) of M31's halo stars and a pronounced red clump (RC) feature. The spatial distribution of RC stars shows a prominent stream feature, the Northwestern (NW) Stream, and a diffuse substructure in the southern part of our survey field. We estimate the distances based on the RC method and obtain (m{--}M) = 24.63 ± 0.191 (random) ± 0.057 (systematic) and 24.29 ± 0.211 (random) ± 0.057 (systematic) mag for the NW Stream and diffuse substructure, respectively, implying that the NW Stream is located behind M31, whereas the diffuse substructure is located in front of it. We also estimate line-of-sight distances along the NW Stream and find that the southern part of the stream is ∼20 kpc closer to us relative to the northern part. The distance to the NW Stream inferred from the isochrone fitting to the color–magnitude diagram favors the RC-based distance, but the tip of the RGB (TRGB)-based distance estimated for NB515-selected RGB stars does not agree with it. The surface number density distribution of RC stars across the NW Stream is found to be approximately Gaussian with an FWHM of ∼25 arcmin (5.7 kpc), with a slight skew to the southwest side. That along the NW Stream shows a complicated structure, including variations in number density and a significant gap in the stream. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Improvement in spatial imagery following sight onset late in childhood.

PubMed

Gandhi, Tapan K; Ganesh, Suma; Sinha, Pawan

2014-03-01

The factors contributing to the development of spatial imagery skills are not well understood. Here, we consider whether visual experience shapes these skills. Although differences in spatial imagery between sighted and blind individuals have been reported, it is unclear whether these differences are truly due to visual deprivation or instead are due to extraneous factors, such as reduced opportunities for the blind to interact with their environment. A direct way of assessing vision's contribution to the development of spatial imagery is to determine whether spatial imagery skills change soon after the onset of sight in congenitally blind individuals. We tested 10 children who gained sight after several years of congenital blindness and found significant improvements in their spatial imagery skills following sight-restoring surgeries. These results provide evidence of vision's contribution to spatial imagery and also have implications for the nature of internal spatial representations.

Shipping InSight Mars Spacecraft to California for Launch

NASA Image and Video Library

2015-12-17

Personnel supporting NASA's InSight mission to Mars load the crated InSight spacecraft into a C-17 cargo aircraft at Buckley Air Force Base, Denver, for shipment to Vandenberg Air Force Base, California. The spacecraft, built in Colorado by Lockheed Martin Space Systems, was shipped Dec. 16, 2015, in preparation for launch from Vandenberg in March 2016. InSight, for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is the first mission dedicated to studying the deep interior of Mars. Its findings will advance understanding of the early history of all rocky planets, including Earth. Note: After thorough examination, NASA managers have decided to suspend the planned March 2016 launch of the Interior Exploration using Seismic Investigations Geodesy and Heat Transport (InSight) mission. The decision follows unsuccessful attempts to repair a leak in a section of the prime instrument in the science payload. http://photojournal.jpl.nasa.gov/catalog/PIA20278

THE SIZE AND EXTENT OF THE INTERSTELLAR GAS CLOUD SURROUNDING THE SUN

NASA Technical Reports Server (NTRS)

2002-01-01

Two astronomical observatories in orbit around the Earth, the Hubble Space Telescope and the Extreme Ultraviolet Explorer, have been used to investigate the structure of the interstellar gas cloud in which the Sun resides. A compilation and interpretation of the results of these studies is being presented today at the American Astronomical Society meeting in Madison, WI by Drs. Jeffrey L. Linsky, Nikolai Piskunov, and Brian E. Wood of JILA and the University of Colorado. Measuring the properties of the local interstellar medium (LISM) is important for understanding how the LISM interacts with the solar wind and for investigating the possibility that changes in the LISM in the immediate vicinity of the Sun could have an effect on the Earth's atmosphere and climate. When astronomers observe the ultraviolet light emitted by nearby stars, it is always found that some of the light is absorbed by atoms and ions in the LISM. The properties of the LISM can therefore be investigated by measuring the amount of absorption observed. Using ultraviolet spectra taken by the Hubble Space Telescope and the Extreme Ultraviolet Explorer, the total amount of local interstellar matter has been measured for many lines of sight through the LISM. These studies suggest that the interstellar gas surrounding the Sun has a temperature of about 7000 K (about 12,000 degrees Fahrenheit) and has a velocity of about 16 miles per second relative to the Sun. Measurements made for very short (less than 10 light years) lines of sight toward very nearby stars suggest an average density of about 0.1 hydrogen atoms per cubic centimeter for the local interstellar gas, hydrogen being by far the most abundant atom in the LISM. Measurements made for lines of sight toward more distant stars suggest lower average densities. This suggests that parts of the lines of sight to these more distant stars are in regions of space with extremely low densities. We believe this means that these stars lie outside the local gas cloud. We can estimate a distance from the Sun to the edge of the local cloud for each line of sight to a star that lies outside the cloud. Combining these measurements, we can then crudely map out the shape of the local cloud. The results are shown as orange ellipsoids in the accompanying illustration. According to this model, the cloud is about 60 light years across along its largest axis, and the Sun is only about 4 light years from the edge. Note that we have very little data toward the Galactic Center. Other data not presented here suggest that the cloud actually extends further in that direction than our crude model suggests. The space outside the local gas cloud is not completely empty, but is instead believed to be occupied by extremely hot (about 1,000,000 K) gas with very low densities (about 0.001 particles per cubic centimeter). The local cloud is in fact thought to reside in a region of space called the 'Local Bubble', in which most of the volume of the bubble consists of this very hot gas. The Local Bubble, which is roughly 300 light years in diameter, may have been created by a supernova explosion. The gas cloud surrounding the Sun is not completely uniform. Different parts of the cloud, which we can perhaps call 'cloudlets', are moving at slightly different speeds and in slightly different directions. The purple ellipsoids in the accompanying illustration indicate our estimate for the size and shape of the cloudlet in which the Sun resides. The crudeness of these models is indicated by the fact that part of the purple ellipsoid actually lies outside the yellow ellipsoid. The purple cloudlet in the illustration is about 30 light years across along its largest axis and the Sun is only about 0.1 light years from the edge of the cloudlet. Furthermore, the Sun's velocity relative to this cloudlet should carry the Sun outside the cloudlet in a few thousand years. Another example of the inhomogeneity of the local cloud is that we have found that the abundance of magnesium varies greatly within the cloud. For one line of sight we find that the abundance of magnesium is consistent with the magnesium abundance found in the Sun (about 39 magnesium atoms per million hydrogen atoms), but for other lines of sight the magnesium abundance is as much as 40 times lower than the solar abundance. For these lines of sight, perhaps most of the magnesium is locked up in dust grains and is therefore undetectable. This work is supported by grants from NASA. For further information, contact: Dr. Jeffrey L. Linsky (303) 492-7838 jlinsky@jila.colorado.edu Dr. Nikolai Piskunov +46-18-51-4490 piskunov@astro.uu.se Brian E. Wood (303) 492-5122 woodb@marmot.colorado.edu FIGURE CAPTION: A model of the gas cloud surrounding the Sun (orange ellipsoid), as seen from three different viewpoints: from the Galactic Center (GC), from the North Galactic Pole (NGP), and from a Galactic longitude of 270 degrees. This model is based on estimates of the location of the edge of the cloud (blue asterisks) made for 15 lines-of-sight to nearby stars. The yellow asterisks mark the locations of 3 very nearby stars that we believe lie inside the local cloud. The Sun's location is indicated by a small black circle. The names of the 18 stars used to probe the shape of the local cloud are given in the figure. The sizes of the asterisks indicate their distances from the point-of-view, with the larger asterisks being in the foreground and the smaller asterisks being in the background. Different parts of the cloud, which we can perhaps call 'cloudlets', are moving at slightly different speeds and in slightly different directions. The purple ellipsoid indicates our estimate for the size and shape of the cloudlet in which the Sun resides.

Applying Sight Translation as a Means to Enhance Reading Ability of Iranian EFL Students

ERIC Educational Resources Information Center

Fatollahi, Moslem

2016-01-01

Sight translation is the oral translation of a written text and is a mixture of translation and interpreting. Sight translation is a widely-used activity in translation training programs. Yet, this mode of translation has rarely been applied as a reading instruction technique in Iranian EFL instruction context in spite of the growing interest in…

Thermal Weapon Sight (TWS) AN/PAS-13 diffractive optics designed for producibility

NASA Technical Reports Server (NTRS)

Anderson, J. Steven; Chen, Chungte W.; Spande, Robert A.

1993-01-01

The Thermal Weapon Sight (TWS) program is a manportable 3-5 micrometer forward-looking-infrared (FLIR) rifle sight. The manportable nature requires that the optics modules be lightweight, low cost and compact while maximizing performance. These objectives were met with diffractive optics. TWS promises to be the first FLIR sensor to incorporate kinoform surfaces in full scale production.

Evaluating a Computer-Based Sight-Word Reading Intervention in a Student with Intellectual Disabilities

ERIC Educational Resources Information Center

Yaw, Jared; Skinner, Christopher H.; Orsega, Michael C.; Parkhurst, John; Booher, Joshua; Chambers, Karen

2012-01-01

The authors used a multiple-baseline-across-behaviors (i.e., word lists) design to evaluate a computer-based flashcard intervention on automatic sight-word reading in a 4th-grade student with moderate to severe intellectual disabilities. Immediately after the intervention was applied to each of three lists of sight words, the student made rapid…

An Analysis of Tonal Patterns Used for Sight-Singing Instruction in Second-Grade General Music Class

ERIC Educational Resources Information Center

Reifinger, James L., Jr.

2009-01-01

This research examined characteristics of a select group of tonal patterns to identify features that may affect the initial acquisition of skill in sight-singing pitch. Second graders (N = 193) individually read and sang 25 tonal patterns on a sight-singing pretest, posttest, and retention test. Between the pre- and posttest, the students…

Relationships among Selected Factors and the Sight-Reading Ability of High School Mixed Choirs.

ERIC Educational Resources Information Center

Daniels, Rose Dwiggins

1986-01-01

This study investigated the relationships among sight-reading ability and selected variables for 20 high school choirs. Results showed that the best predictors of sight-reading ability are ethnic makeup of the school, presence of a piano in the home, a rural school location, and occasional use of rote procedures to teach music. (JDH)

Education of the Blind and People with Weak Sight in the USSR.

ERIC Educational Resources Information Center

Zemtsova, M.

Described with accompanying photographs is education for blind and partially sighted children between 7 and 20 years of age in special residential schools in the Soviet Union. Discussed is vocational education in 120 vocational polytechnic schools for the blind and partially sighted from 1st to 11th forms (grades), sanatorium schools from 1st to…

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

Tim Dunn, launch director, NASA’s Launch Services Program, discusses NASA's InSight mission during a prelaunch media briefing, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

A video showing NASA's InSight spacecraft separating from the Atlas V rocket is seen during a prelaunch media briefing, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

Andy Klesh, MarCO chief engineer, NASA JPL, discusses NASA's InSight mission during a prelaunch media briefing, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

InSight Prelaunch

NASA Image and Video Library

2018-05-04

A heavy fog rolls in as the United Launch Alliance (ULA) Atlas-V rocket with NASA's InSight spacecraft onboard awaits launch, Friday, May 4, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

Tilman Spohn, HP3 investigation lead, Institute of Planetary Research (DLR), discusses NASA's InSight mission during a prelaunch media briefing, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

Annick Sylvestre-Baron, SEIS deputy project manager, CNES, discusses NASA's InSight mission during a prelaunch media briefing, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

Scott Messer, United Launch Alliance program manager for NASA missions, discusses NASA's InSight mission during a prelaunch media briefing, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

Stephanie Smith, Digital & Social Media Supervisor, Jet Propulsion Laboratory moderates a prelaunch media briefing for the NASA InSight mission, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

Shipping InSight Mars Spacecraft to Buckley Air Force Base

NASA Image and Video Library

2018-02-28

A truck carrying NASA s InSight spacecraft leaves Lockheed Martin Space, Denver, where the spacecraft was built and tested, on February 28, 2018. InSight was driven to Buckley Air Force Base, where it was loaded into a C-17 cargo aircraft and flown to Vandenberg Air Force Base, California. There, it will be prepared for a May launch. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is the first mission dedicated to studying the deep interior of Mars. Its findings will advance understanding of the early history of all rocky planets, including Earth. https://photojournal.jpl.nasa.gov/catalog/PIA22225

InSight Encapsulation

NASA Image and Video Library

2018-04-16

In the Astrotech facility at Vandenberg Air Force Base in California, NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander is encapsulated in its payload fairing. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

An analysis of initial acquisition and maintenance of sight words following picture matching and copy cover, and compare teaching methods.

PubMed

Conley, Colleen M; Derby, K Mark; Roberts-Gwinn, Michelle; Weber, Kimberly P; McLaughlin, T E

2004-01-01

This study compared the copy, cover, and compare method to a picture-word matching method for teaching sight word recognition. Participants were 5 kindergarten students with less than preprimer sight word vocabularies who were enrolled in a public school in the Pacific Northwest. A multielement design was used to evaluate the effects of the two interventions. Outcomes suggested that sight words taught using the copy, cover, and compare method resulted in better maintenance of word recognition when compared to the picture-matching intervention. Benefits to students and the practicality of employing the word-level teaching methods are discussed.

InSight Encapsulation

NASA Image and Video Library

2018-04-16

In the Astrotech facility at Vandenberg Air Force Base in California, technicians and engineers encapsulate NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander in its payload fairing. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

Encapsulated in its payload fairing, NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander is transported to Space Launch Complex 3 at Vandenberg Air Force Base in California. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

Encapsulated in its payload fairing NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander arrives at Space Launch Complex 3 at Vandenberg Air Force Base in California. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

Encapsulated in its payload fairing NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander is transported to Space Launch Complex 3 at Vandenberg Air Force Base in California. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Lift & Mate

NASA Image and Video Library

2018-04-23

Encapsulated in its payload fairing NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander is prepared for transport to Space Launch Complex 3 at Vandenberg Air Force Base in California. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

Shipping InSight Mars Spacecraft to California for Launch

NASA Image and Video Library

2018-02-28

Personnel supporting NASA's InSight mission to Mars load the crated InSight spacecraft into a C-17 cargo aircraft at Buckley Air Force Base, Denver, for shipment to Vandenberg Air Force Base, California. The spacecraft, built in Colorado by Lockheed Martin Space, was shipped February 28, 2018, in preparation for launch from Vandenberg in May 2018. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is the first mission dedicated to studying the deep interior of Mars. Its findings will advance understanding of the early history of all rocky planets, including Earth. https://photojournal.jpl.nasa.gov/catalog/PIA22220

Shipping InSight Mars Spacecraft to California for Launch

NASA Image and Video Library

2018-02-28

Personnel supporting NASA's InSight mission to Mars load the crated InSight spacecraft into a C-17 cargo aircraft at Buckley Air Force Base, Denver, for shipment to Vandenberg Air Force Base, California. The spacecraft, built in Colorado by Lockheed Martin Space, was shipped February 28, 2018, in preparation for launch from Vandenberg in May 2018. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is the first mission dedicated to studying the deep interior of Mars. Its findings will advance understanding of the early history of all rocky planets, including Earth. https://photojournal.jpl.nasa.gov/catalog/PIA22252

Shipping InSight Mars Spacecraft to California for Launch

NASA Image and Video Library

2018-02-28

Personnel supporting NASA's InSight mission to Mars load the crated InSight spacecraft into a C-17 cargo aircraft at Buckley Air Force Base, Denver, for shipment to Vandenberg Air Force Base, California. The spacecraft, built in Colorado by Lockheed Martin Space, was shipped February 28, 2018, in preparation for launch from Vandenberg in May 2018. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is the first mission dedicated to studying the deep interior of Mars. Its findings will advance understanding of the early history of all rocky planets, including Earth. https://photojournal.jpl.nasa.gov/catalog/PIA22253

InSight Battery Installation

NASA Image and Video Library

2018-04-20

In the gantry at Space Launch Complex 3 at Vandenberg Air Force Base in California, a technician prepares batteries for installation in NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

GABA release in the zona incerta of the sheep in response to the sight and ingestion of food and salt.

PubMed

Kendrick, K M; Hinton, M R; Baldwin, B A

1991-05-31

In order to establish which neurotransmitters may influence the activity of zona incerta neurones in the sheep which respond selectively to the sight or ingestion of food, we have measured the release of amino acid and monoamine neurotransmitters from this region using microdialysis sampling. Co-ordinates for the placement of microdialysis probes in regions of the zona incerta where cells respond to the sight or ingestion of food were first established by making single-unit extracellular recordings. When animals were food-deprived results showed that release of gamma-aminobutyric acid (GABA) was increased in response to the sight and ingestion of food but not of aspartate, glutamate, taurine, noradrenaline, dopamine or serotonin. This release of GABA was absent when the animals were shown non-food objects or saw or ingested salt solutions. When the same animals were physiologically sodium-depleted GABA release was evoked by the sight and ingestion of salt solutions and release following the sight and ingestion of food was significantly reduced. These results provide further evidence that GABA is an important neurotransmitter in neural circuits controlling the regulation of food intake.

From Perception to Metacognition: Auditory and Olfactory Functions in Early Blind, Late Blind, and Sighted Individuals

PubMed Central

Cornell Kärnekull, Stina; Arshamian, Artin; Nilsson, Mats E.; Larsson, Maria

2016-01-01

Although evidence is mixed, studies have shown that blind individuals perform better than sighted at specific auditory, tactile, and chemosensory tasks. However, few studies have assessed blind and sighted individuals across different sensory modalities in the same study. We tested early blind (n = 15), late blind (n = 15), and sighted (n = 30) participants with analogous olfactory and auditory tests in absolute threshold, discrimination, identification, episodic recognition, and metacognitive ability. Although the multivariate analysis of variance (MANOVA) showed no overall effect of blindness and no interaction with modality, follow-up between-group contrasts indicated a blind-over-sighted advantage in auditory episodic recognition, that was most pronounced in early blind individuals. In contrast to the auditory modality, there was no empirical support for compensatory effects in any of the olfactory tasks. There was no conclusive evidence for group differences in metacognitive ability to predict episodic recognition performance. Taken together, the results showed no evidence of an overall superior performance in blind relative sighted individuals across olfactory and auditory functions, although early blind individuals exceled in episodic auditory recognition memory. This observation may be related to an experience-induced increase in auditory attentional capacity. PMID:27729884

Mapping the Asymmetric Thick Disk. III. The Kinematics and Interaction with the Galactic Bar

NASA Astrophysics Data System (ADS)

Humphreys, Roberta M.; Beers, Timothy C.; Cabanela, Juan E.; Grammer, Skyler; Davidson, Kris; Lee, Young Sun; Larsen, Jeffrey A.

2011-04-01

In the first two papers of this series, Larsen et al. describe our faint CCD survey in the inner Galaxy and map the overdensity of thick disk stars in Quadrant 1 (Q1) to 5 kpc or more along the line of sight. The regions showing the strongest excess are above the density contours of the bar in the Galactic disk. In this third paper on the asymmetric thick disk, we report on radial velocities and derived metallicity parameters for over 4000 stars in Q1, above and below the plane, and in Quadrant 4 (Q4) above the plane. We confirm the corresponding kinematic asymmetry first reported by Parker et al., extended to greater distances and with more spatial coverage. The thick disk stars in Q1 have a rotational lag of 60-70 km s-1 relative to circular rotation, and the metal-weak thick disk stars have an even greater lag of 100 km s-1. Both lag their corresponding populations in Q4 by ≈30 km s-1. Interestingly, the disk stars in Q1 also appear to participate in the rotational lag by about 30 km s-1. The enhanced rotational lag for the thick disk in Q1 extends to 4 kpc or more from the Sun. At 3-4 kpc, our sight lines extend above the density contours on the near side of the bar, and as our lines of sight pass directly over the bar the rotational lag appears to decrease. This is consistent with a "gravitational wake" induced by the rotating bar in the disk which would trap and pile up stars behind it. We conclude that a dynamical interaction with the stellar bar is the most probable explanation for the observed kinematic and spatial asymmetries. Based on observations obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona, and at the Cerro Tololo Inter-American Observatory (NOAO) operated by the Association of Universities for Research in Astronomy (AURA).

HAWC+/SOFIA observations of Rho Oph A: far-infrared polarization spectrum

NASA Astrophysics Data System (ADS)

Santos, Fabio; Dowell, Charles D.; Houde, Martin; Looney, Leslie; Lopez-Rodriguez, Enrique; Novak, Giles; Ward-Thompson, Derek; HAWC+ Science Team

2018-01-01

In this work, we present preliminary results from the HAWC+ far-infrared polarimeter that operates on the SOFIA airborne observatory. The densest portions of the Rho Ophiuchi molecular complex, known as Rho Oph A, have been mapped using HAWC+ bands C (89 microns) and D (155 microns). Rho Oph A is a well known nearby star forming region. At the target's distance of approximately 130 pc, our observations provide excellent spatial resolution (~5 mpc in band C).The magnetic field map suggests a compressed and distorted field morphology around Oph S1, a massive B3 star that is the main heat source of Rho Oph A. We compute the ratio p(D)/p(C), where p(C) and p(D) are the polarization degree maps at bands C and D, respectively. This ratio estimates the slope of the polarization spectrum in the far-infrared. Although the slope is predicted to be positive by dust grain models, previous observations of other molecular clouds have revealed that negative slopes are common. In Rho Oph A, we find that there is a smooth gradient of p(D)/p(C) across the mapped field. The change in p(D)/p(C) is well correlated with the integrated NH3 (1,1) emission. A positive slope dominates the lower density and well illuminated portions of the cloud, whereas a transition to a negative slope is observed at the denser and less evenly illuminated cloud core.We interpret the positive to negative slope transition as being consistent with the radiative torques (RATs) grain alignment theory. For the sight lines of higher column density, polarized emission from the warmer outer cloud layers is added to emission from the colder inner well-shielded layers lying along the same line-of-sight. Given that the outer layers receive more radiation from Oph S1, their grain alignment efficiency is expected to be higher according to RATs. The combination of warmer, well aligned grains with cooler, poorly aligned grains is what causes the negative slope. This effect is not present in the sight lines of lower column density, due to the much lower extinction.

Sensitivity of Chaos Measures in Detecting Stress in the Focusing Control Mechanism of the Short-Sighted Eye.

PubMed

Hampson, Karen M; Cufflin, Matthew P; Mallen, Edward A H

2017-08-01

When fixating on a stationary object, the power of the eye's lens fluctuates. Studies have suggested that changes in these so-called microfluctuations in accommodation may be a factor in the onset and progression of short-sightedness. Like many physiological signals, the fluctuations in the power of the lens exhibit chaotic behaviour. A breakdown or reduction in chaos in physiological systems indicates stress to the system or pathology. The purpose of this study was to determine whether the chaos in fluctuations of the power of the lens changes with refractive error, i.e. how short-sighted a subject is, and/or accommodative demand, i.e. the effective distance of the object that is being viewed. Six emmetropes (EMMs, non-short-sighted), six early-onset myopes (EOMs, onset of short-sightedness before the age of 15), and six late-onset myopes (LOMs, onset of short-sightedness after the age of 15) took part in the study. Accommodative microfluctuations were measured at 22 Hz using an SRW-5000 autorefractor at accommodative demands of 1 D (dioptres), 2 D, and 3 D. Chaos theory analysis was used to determine the embedding lag, embedding dimension, limit of predictability, and Lyapunov exponent. Topological transitivity was also tested for. For comparison, the power spectrum and standard deviation were calculated for each time record. The EMMs had a statistically significant higher Lyapunov exponent than the LOMs ([Formula: see text] vs. [Formula: see text]) and a lower embedding dimension than the LOMs ([Formula: see text] vs. [Formula: see text]). There was insufficient evidence (non-significant p value) of a difference between EOMs and EMMs or EOMs and LOMs. The majority of time records were topologically transitive. There was insufficient evidence of accommodative demand having an effect. Power spectrum analysis and assessment of the standard deviation of the fluctuations failed to discern differences based on refractive error. Chaos differences in accommodation microfluctuations indicate that the control system for LOMs is under stress in comparison to EMMs. Chaos theory analysis is a more sensitive marker of changes in accommodation microfluctuations than traditional analysis methods.

Stand-off CWA imaging system: second sight MS

NASA Astrophysics Data System (ADS)

Bernascolle, Philippe F.; Elichabe, Audrey; Fervel, Franck; Haumonté, Jean-Baptiste

2012-06-01

In recent years, several manufactures of IR imaging devices have launched commercial models applicable to a wide range of chemical species. These cameras are rugged and sufficiently sensitive to detect low concentrations of toxic and combustible gases. Bertin Technologies, specialized in the design and supply of innovating systems for industry, defense and health, has developed a stand-off gas imaging system using a multi-spectral infrared imaging technology. With this system, the gas cloud size, localization and evolution can be displayed in real time. This technology was developed several years ago in partnership with the CEB, a French MoD CBRN organization. The goal was to meet the need for early warning caused by a chemical threat. With a night & day efficiency of up to 5 km, this process is able to detect Chemical Warfare Agents (CWA), critical Toxic Industrial Compounds (TIC) and also flammable gases. The system has been adapted to detect industrial spillage, using off-the-shelf uncooled infrared cameras, allowing 24/7 surveillance without costly frequent maintenance. The changes brought to the system are in compliance with Military Specifications (MS) and primarily focus on the signal processing improving the classification of the detected products and on the simplification of the Human Machine Interface (HMI). Second Sight MS is the only mass produced, passive stand-off CWA imaging system with a wide angle (up to 60°) already used by several regular armies around the world. This paper examines this IR gas imager performance when exposed to several CWA, TIC and simulant compounds. First, we will describe the Second Sight MS system. The theory of gas detection, visualization and classification functions has already been described elsewhere, so we will just summarize it here. We will then present the main topic of this paper which is the results of the tests done in laboratory on live agents and in open field on simulant. The sensitivity threshold of the camera measured in laboratory, on some CWA (G, H agents...) and TIC (ammonia, sulfur dioxide...) will be given. The result of the detection and visualization of a gas cloud in open field testing for some simulants (DMMP, SF6) at a far distance will be also shown.

Short-term velocity measurements at Columbia Glacier, Alaska; August-September 1984

USGS Publications Warehouse

Vaughn, B.H.; Raymond, C.F.; Rasmussen, Lowell A.; Miller, D.S.; Michaelson, C.A.; Meier, M.F.; Krimmel, R.M.; Fountain, A.G.; Dunlap, W.W.; Brown, C.S.

1985-01-01

Ice velocity data are presented for the lower reach of Columbia Glacier, Alaska. The data span a 29 day period and contain 1,072 angle sightings from two survey stations to 22 markers placed on the ice surface, and 1,621 laser measurements of the distance to one of those markers (number 11) from another station. These short-interval observations were made to investigate the dynamics of the glacier and to provide input to models for estimation of future retreat and iceberg discharge. The mean ice velocity (at marker number 11) was approximately 9 m/day and ranged from 8 to < 15 m/day. The data set includes a well defined 2-day, 50% velocity increase and a clear pattern of velocity fluctuations of about 5% with approximately diurnal and semiurnal periods. (Author 's abstract)

Automated alignment system for optical wireless communication systems using image recognition.

PubMed

Brandl, Paul; Weiss, Alexander; Zimmermann, Horst

2014-07-01

In this Letter, we describe the realization of a tracked line-of-sight optical wireless communication system for indoor data distribution. We built a laser-based transmitter with adaptive focus and ray steering by a microelectromechanical systems mirror. To execute the alignment procedure, we used a CMOS image sensor at the transmitter side and developed an algorithm for image recognition to localize the receiver's position. The receiver is based on a self-developed optoelectronic integrated chip with low requirements on the receiver optics to make the system economically attractive. With this system, we were able to set up the communication link automatically without any back channel and to perform error-free (bit error rate <10⁻⁹) data transmission over a distance of 3.5 m with a data rate of 3 Gbit/s.

X-ray transport and radiation response assessment (XTRRA) experiments at the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fournier, K. B., E-mail: fournier2@llnl.gov; Brown, C. G.; Yeoman, M. F.

2016-11-15

Our team has developed an experimental platform to evaluate the x-ray-generated stress and impulse in materials. Experimental activities include x-ray source development, design of the sample mounting hardware and sensors interfaced to the National Ignition Facility’s diagnostics insertion system, and system integration into the facility. This paper focuses on the X-ray Transport and Radiation Response Assessment (XTRRA) test cassettes built for these experiments. The test cassette is designed to position six samples at three predetermined distances from the source, each known to within ±1% accuracy. Built-in calorimeters give in situ measurements of the x-ray environment along the sample lines ofmore » sight. The measured accuracy of sample responses as well as planned modifications to the XTRRA cassette is discussed.« less

Overview of RFID technology and its applications in the food industry.

PubMed

Kumar, P; Reinitz, H W; Simunovic, J; Sandeep, K P; Franzon, P D

2009-10-01

Radio frequency identification (RFID) is an alternative technology with a potential to replace traditional universal product code (UPC) barcodes. RFID enables identification of an object from a distance without requiring a line of sight. RFID tags can also incorporate additional data such as details of product and manufacturer and can transmit measured environmental factors such as temperature and relative humidity. This article presents key concepts and terminology related to RFID technology and its applications in the food industry. Components and working principles of an RFID system are described. Numerous applications of RFID technology in the food industry (supply chain management, temperature monitoring of foods, and ensuring food safety) are discussed. Challenges in implementation of RFID technology are also discussed in terms of read range, read accuracy, nonuniform standards, cost, recycling issues, privacy, and security concerns.

Constraints on frequency-dependent violations of Shapiro delay from GW150914

NASA Astrophysics Data System (ADS)

Kahya, Emre O.; Desai, Shantanu

2016-05-01

On 14th September 2015, a transient gravitational wave (GW150914) was detected by the two LIGO detectors at Hanford and Livingston from the coalescence of a binary black hole system located at a distance of about 400 Mpc. We point out that GW150914 experienced a Shapiro delay due to the gravitational potential of the mass distribution along the line of sight of about 1800 days. Also, the near-simultaneous arrival of gravitons over a frequency range of about 200 Hz within a 0.2 s window allows us to constrain any violations of Shapiro delay and Einstein's equivalence principle between the gravitons at different frequencies. From the calculated Shapiro delay and the observed duration of the signal, frequency-dependent violations of the equivalence principle for gravitons are constrained to an accuracy of O (10-9).

Interferometric Synthetic Aperture Radar (InSAR)

USGS Publications Warehouse

Dzurisin, D.; Lu, Z.

2006-01-01

Geodesists are, for the most part, a patient and hardworking lot. A day spent hiking to a distant peak, hours spent waiting for clouds to clear a line-of-sight between observation points, weeks spent moving methodically along a level line — such is the normal pulse of the geodetic profession. The fruits of such labors are all the more precious because they are so scarce. A good day spent with an electronic distance meter (EDM) or level typically produces fewer than a dozen data points. A year of tiltmeter output sampled at ten-minute intervals constitutes less than half a megabyte of data. All of the leveling data ever collected at Yellowstone Caldera fit comfortably on a single PC diskette! These quantities are trivial by modern datastorage standards, in spite of the considerable efforts expended to produce them.

Interferometric synthetic-aperature radar (InSAR): Chapter 5

USGS Publications Warehouse

Dzurisin, Daniel; Lu, Zhong

2007-01-01

Geodesists are, for the most part, a patient and hardworking lot. A day spent hiking to a distant peak, hours spent waiting for clouds to clear a line-of-sight between observation points, weeks spent moving methodically along a level line – such is the normal pulse of the geodetic profession. The fruits of such labors are all the more precious because they are so scarce. A good day spent with an electronic distance meter (EDM) or level typically produces fewer than a dozen data points. A year of tiltmeter output sampled at ten-minute intervals constitutes less than half a megabyte of data. All of the leveling data ever collected at Yellowstone Caldera fit comfortably on a single PC diskette. These quantities are trivial by modern data-storage standards, in spite of the considerable efforts expended to produce them.

Postselection-Loophole-Free Bell Test Over an Installed Optical Fiber Network.

PubMed

Carvacho, Gonzalo; Cariñe, Jaime; Saavedra, Gabriel; Cuevas, Álvaro; Fuenzalida, Jorge; Toledo, Felipe; Figueroa, Miguel; Cabello, Adán; Larsson, Jan-Åke; Mataloni, Paolo; Lima, Gustavo; Xavier, Guilherme B

2015-07-17

Device-independent quantum communication will require a loophole-free violation of Bell inequalities. In typical scenarios where line of sight between the communicating parties is not available, it is convenient to use energy-time entangled photons due to intrinsic robustness while propagating over optical fibers. Here we show an energy-time Clauser-Horne-Shimony-Holt Bell inequality violation with two parties separated by 3.7 km over the deployed optical fiber network belonging to the University of Concepción in Chile. Remarkably, this is the first Bell violation with spatially separated parties that is free of the postselection loophole, which affected all previous in-field long-distance energy-time experiments. Our work takes a further step towards a fiber-based loophole-free Bell test, which is highly desired for secure quantum communication due to the widespread existing telecommunication infrastructure.

Wireless Sensor Node for Autonomous Monitoring and Alerts in Remote Environments

NASA Technical Reports Server (NTRS)

Panangadan, Anand V. (Inventor); Monacos, Steve P. (Inventor)

2015-01-01

A method, apparatus, system, and computer program products provides personal alert and tracking capabilities using one or more nodes. Each node includes radio transceiver chips operating at different frequency ranges, a power amplifier, sensors, a display, and embedded software. The chips enable the node to operate as either a mobile sensor node or a relay base station node while providing a long distance relay link between nodes. The power amplifier enables a line-of-sight communication between the one or more nodes. The sensors provide a GPS signal, temperature, and accelerometer information (used to trigger an alert condition). The embedded software captures and processes the sensor information, provides a multi-hop packet routing protocol to relay the sensor information to and receive alert information from a command center, and to display the alert information on the display.

Grey Milky Way extinction from SDSS stellar photometry

NASA Astrophysics Data System (ADS)

Gorbikov, Evgeny; Brosch, Noah

2010-01-01

We report results concerning the distribution and properties of galactic extinction at high galactic latitudes derived from stellar statistics using the Sloan Digital Sky Survey (SDSS). We use the classical Wolf diagram method to identify regions with extinction, and derive the extinction and the extinction law of the dust using all five SDSS spectral bands. We estimate the distance to the extinguishing medium using simple assumptions about the stellar populations in the line of sight. We report the identification of three extinguishing clouds, each a few tens of pc wide, producing 0.2-0.4 mag of g'-band extinction, located 1-2 kpc away or 0.5-1 kpc above the Galactic plane. All clouds exhibit grey extinction, i.e. almost wavelength independent in the limited spectral range of the SDSS. We discuss the implication of this finding on general astrophysical questions.

Postselection-Loophole-Free Bell Test Over an Installed Optical Fiber Network

NASA Astrophysics Data System (ADS)

Carvacho, Gonzalo; Cariñe, Jaime; Saavedra, Gabriel; Cuevas, Álvaro; Fuenzalida, Jorge; Toledo, Felipe; Figueroa, Miguel; Cabello, Adán; Larsson, Jan-Åke; Mataloni, Paolo; Lima, Gustavo; Xavier, Guilherme B.

2015-07-01

Device-independent quantum communication will require a loophole-free violation of Bell inequalities. In typical scenarios where line of sight between the communicating parties is not available, it is convenient to use energy-time entangled photons due to intrinsic robustness while propagating over optical fibers. Here we show an energy-time Clauser-Horne-Shimony-Holt Bell inequality violation with two parties separated by 3.7 km over the deployed optical fiber network belonging to the University of Concepción in Chile. Remarkably, this is the first Bell violation with spatially separated parties that is free of the postselection loophole, which affected all previous in-field long-distance energy-time experiments. Our work takes a further step towards a fiber-based loophole-free Bell test, which is highly desired for secure quantum communication due to the widespread existing telecommunication infrastructure.

X-ray transport and radiation response assessment (XTRRA) experiments at the National Ignition Facility

DOE PAGES

Fournier, K. B.; Brown, Jr., C. G.; Yeoman, M. F.; ...

2016-08-10

Our team has developed an experimental platform to evaluate the x-ray-generated stress and impulse in materials. Experimental activities include x-ray source development, design of the sample mounting hardware and sensors interfaced to the NIF’s diagnostics insertion system, and system integration into the facility. This paper focuses on the X-ray Transport and Radiation Response Assessment (XTRRA) test cassettes built for these experiments. The test cassette is designed to position six samples at three predetermined distances from the source, each known to within ±1% accuracy. Built in calorimeters give in situ measurements of the x-ray environment along the sample lines of sight.more » We discuss the measured accuracy of sample responses, as well as planned modifications to the XTRRA cassette.« less

The influence of environmental variables on the presence of white sharks, Carcharodon carcharias at two popular Cape Town bathing beaches: a generalized additive mixed model.

PubMed

Weltz, Kay; Kock, Alison A; Winker, Henning; Attwood, Colin; Sikweyiya, Monwabisi

2013-01-01

Shark attacks on humans are high profile events which can significantly influence policies related to the coastal zone. A shark warning system in South Africa, Shark Spotters, recorded 378 white shark (Carcharodon carcharias) sightings at two popular beaches, Fish Hoek and Muizenberg, during 3690 six-hour long spotting shifts, during the months September to May 2006 to 2011. The probabilities of shark sightings were related to environmental variables using Binomial Generalized Additive Mixed Models (GAMMs). Sea surface temperature was significant, with the probability of shark sightings increasing rapidly as SST exceeded 14 °C and approached a maximum at 18 °C, whereafter it remains high. An 8 times (Muizenberg) and 5 times (Fish Hoek) greater likelihood of sighting a shark was predicted at 18 °C than at 14 °C. Lunar phase was also significant with a prediction of 1.5 times (Muizenberg) and 4 times (Fish Hoek) greater likelihood of a shark sighting at new moon than at full moon. At Fish Hoek, the probability of sighting a shark was 1.6 times higher during the afternoon shift compared to the morning shift, but no diel effect was found at Muizenberg. A significant increase in the number of shark sightings was identified over the last three years, highlighting the need for ongoing research into shark attack mitigation. These patterns will be incorporated into shark awareness and bather safety campaigns in Cape Town.

The Influence of Environmental Variables on the Presence of White Sharks, Carcharodon carcharias at Two Popular Cape Town Bathing Beaches: A Generalized Additive Mixed Model

PubMed Central

Weltz, Kay; Kock, Alison A.; Winker, Henning; Attwood, Colin; Sikweyiya, Monwabisi

2013-01-01

Shark attacks on humans are high profile events which can significantly influence policies related to the coastal zone. A shark warning system in South Africa, Shark Spotters, recorded 378 white shark (Carcharodon carcharias) sightings at two popular beaches, Fish Hoek and Muizenberg, during 3690 six-hour long spotting shifts, during the months September to May 2006 to 2011. The probabilities of shark sightings were related to environmental variables using Binomial Generalized Additive Mixed Models (GAMMs). Sea surface temperature was significant, with the probability of shark sightings increasing rapidly as SST exceeded 14°C and approached a maximum at 18°C, whereafter it remains high. An 8 times (Muizenberg) and 5 times (Fish Hoek) greater likelihood of sighting a shark was predicted at 18°C than at 14°C. Lunar phase was also significant with a prediction of 1.5 times (Muizenberg) and 4 times (Fish Hoek) greater likelihood of a shark sighting at new moon than at full moon. At Fish Hoek, the probability of sighting a shark was 1.6 times higher during the afternoon shift compared to the morning shift, but no diel effect was found at Muizenberg. A significant increase in the number of shark sightings was identified over the last three years, highlighting the need for ongoing research into shark attack mitigation. These patterns will be incorporated into shark awareness and bather safety campaigns in Cape Town. PMID:23874668

JPL-20180504-INSIGHf-0001-NASA's First Mission to Study the Interior of Mars Awaits Launch

NASA Image and Video Library

2018-05-04

Pre-launch video file. InSight's launch to Mars is scheduled for as early as May 5, 2018. Animations: Launch visibility. EDL. Instrument deployments. HP3. Detecting a marsquake. MarCO cubesats. Video: InSight being built at Lockheed Martin Space, Denver. Atlas V rocket and encapsulated InSight spacecraft. How the Atlas V performs this mission.

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

Jason Townsend, NASA's Deputy Social Media Manager, reads questions submitted by online social media followers during a prelaunch media briefing for NASA's InSight mission, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

An Analysis of Initial Acquisition and Maintenance of Sight Words Following Picture Matching and Copy, Cover, and Compare Teaching Methods

ERIC Educational Resources Information Center

Conley, Colleen M.; Derby, K. Mark; Roberts-Gwinn, Michelle; Weber, Kimberly P.; McLaughlin, T.F.

2004-01-01

This study compared the copy, cover, and compare method to a picture-word matching method for teaching sight word recognition. Participants were 5 kindergarten students with less than preprimer sight word vocabularies who were enrolled in a public school in the Pacific Northwest. A multielement design was used to evaluate the effects of the two…

InSight Prelaunch

NASA Image and Video Library

2018-05-04

NASA social media attendees pose for a group photograph in front of the United Launch Alliance (ULA) Atlas-V rocket with NASA's InSight spacecraft onboard, Friday, May 4, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

The Way We Do the Things We Do: A Survey of Middle-School Choral Educators' Sight-Singing Attitudes and Influences

ERIC Educational Resources Information Center

Nichols, Bryan

2013-01-01

This study explored the rationale for sight-singing instructional choices of chorus teachers at the middle school level and sought to determine teachers' commitment to teaching music literacy. Three research questions formed the basis of the study: (1) what is the prevalence of sight-singing instruction in choral music classes, (2) what is…

Verbalism in the Narrative Language of Children Who Are Blind and Sighted

ERIC Educational Resources Information Center

Rosel, Jesus; Caballer, Antonio; Jara, Pilar; Oliver, Juan Carlos

2005-01-01

This study examined the use of verbalisms by 62 children aged 7-14 who were totally blind from birth and 64 sighted children. It found that a child's degree of sight and gender did not affect the frequency with which verbalisms were used; only age had a significant positive effect. The study shows that language is a flexible structure that is used…

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

1st Lieutenant Kristina Williams, weather officer, 30th Space Wing, Vandenberg Air Force Base, discusses NASA's InSight mission during a prelaunch media briefing, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

InSight Prelaunch

NASA Image and Video Library

2018-05-04

The United Launch Alliance (ULA) Atlas-V rocket with the NASA InSight spacecraft onboard is seen shortly after the mobile service tower was rolled back, Friday, May 4, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

InSight Prelaunch

NASA Image and Video Library

2018-05-05

The United Launch Alliance (ULA) Atlas-V rocket with the NASA InSight spacecraft onboard is seen shortly after the mobile service tower was rolled back, Friday, May 4, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

Philippe Lognonné, SEIS investigation lead, Institut de Physique du Globe de Paris (IPGP) discusses NASA's InSight mission during a prelaunch media briefing, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

InSight Prelaunch Briefing

NASA Image and Video Library

2018-05-03

Col. Michael Hough, Commander 30th Space Wing, Vandenberg Air Force Base, discusses NASA's InSight mission during a prelaunch media briefing, Thursday, May 3, 2018, at Vandenberg Air Force Base in California. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to study the "inner space" of Mars: its crust, mantle, and core. Photo Credit: (NASA/Bill Ingalls)

Sperm whales (Physeter catodon) in the Gulf of Mexico

USGS Publications Warehouse

Collum, L.A.; Fritts, T.H.

1985-01-01

The distribution of the sperm whale, Physeter catodon, was documented in the Gulf of Mexico during 1979 to 1981 using regular aerial surveys and opportunistic sightings from ships. Most sightings were in the western Gulf of Mexico in deep waters near the edge of the continental shelf. A total of 47 adults and 12 young animals was sighted in groups containing from one to 14 animals.

The InSight Team at Lockheed Martin

NASA Image and Video Library

2018-01-25

The InSight Team at Lockheed Martin Space in May 2017 The InSight team is comprised of scientists and engineers from multiple disciplines and is a unique collaboration between countries and organizations around the world. The science team includes co-investigators from the U.S., France, Germany, Austria, Belgium, Canada, Japan, Switzerland and the United Kingdom. https://photojournal.jpl.nasa.gov/catalog/PIA22235

The InSight Team at JPL

NASA Image and Video Library

2018-01-25

The InSight Team at NASA's Jet Propulsion Laboratory, JPL, in June 2015. The InSight team is comprised of scientists and engineers from multiple disciplines and is a unique collaboration between countries and organizations around the world. The science team includes co-investigators from the U.S., France, Germany, Austria, Belgium, Canada, Japan, Switzerland and the United Kingdom. https://photojournal.jpl.nasa.gov/catalog/PIA22234

InSight Mission Education and Communication: Powerhouse partners leverage global networks to put authentic planetary science into the hands and minds of students of all ages

NASA Astrophysics Data System (ADS)

Banerdt, W. B.; Jones, J. H.

2015-12-01

InSight Mission Education and Communication: Powerhouse Partners Leverage Global Networks To Put Authentic Planetary Science into the Hands and Minds of Students. NASA's InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is a NASA Discovery Program mission that will place a single geophysical lander on Mars to study its deep interior. InSight will launch in March 2016 aboard an Atlas V 401 rocket from Space Launch Complex 3E at Vandenberg Air Force Base in California, and land on Mars in September 2016, beginning science return in October 2016.By using sophisticated geophysical instruments, InSight will delve deep beneath the surface of Mars, detecting the fingerprints of the processes of terrestrial planet formation, as well as measuring the planet's "vital signs": Its "pulse" (seismology), "temperature" (heat flow probe), and "reflexes" (precision tracking). InSight's E/PO Partners all of which already work with NSF, Department of Education and NASA will put authentic Mars data and analysis tools in the hands of educators, students and the public. IRIS - Incorporated Research Institutions for Seismology provides lessons, seismograph software, animations, videos, and will use InSight data to focus on how students can compare seismic data from Mars and Earth. SCEC - Southern California Earthquake Center's "Vital Signs of the Planet" professional development program for science teachers is creating, and test teaching standards-aligned STEM materials to help additional teachers work with comparative planetary concepts. They are also installinglow cost strong motion research accelerometers in all participating schools. ASP - Astronomical Society of the Pacific will deliver Planet Core Outreach toolkits with an InSight focus to 380 amateur astronomy clubs engaged in Informal Education. Space Math - delivered twenty standards based mathematics lessons using InSight and Mars physical and science data which enable students to acquire skills in collecting, organizing and graphing data, making inferences and drawing conclusions. International partners in France, US, UK, CH and Germany also have complimentary education initiatives and partner with IRIS and SCEC in their countries.

Model of Mars-Bound MarCO CubeSat

NASA Image and Video Library

2015-06-12

Engineers for NASA's MarCO technology demonstration display a full-scale mechanical mock-up of the small craft in development as part of NASA's next mission to Mars. Mechanical engineer Joel Steinkraus and systems engineer Farah Alibay are on the team at NASA's Jet Propulsion Laboratory, Pasadena, California, preparing twin MarCO (Mars Cube One) CubeSats for a March 2016 launch. MarCO is the first interplanetary mission using CubeSat technologies for small spacecraft. The briefcase-size MarCO twins will ride along on an Atlas V launch vehicle lifting off from Vandenberg Air Force Base, California, with NASA's next Mars lander, InSight. The mock-up in the photo is in a configuration to show the deployed position of components that correspond to MarCO's two solar panels and two antennas. During launch, those components will be stowed for a total vehicle size of about 14.4 inches (36.6 centimeters) by 9.5 inches (24.3 centimeters) by 4.6 inches (11.8 centimeters). After launch, the two MarCO CubeSats and InSight will be navigated separately to Mars. The MarCO twins will fly past the planet in September 2016 just as InSight is descending through the atmosphere and landing on the surface. MarCO is a technology demonstration mission to relay communications from InSight to Earth during InSight's descent and landing. InSight communications during that critical period will also be recorded by NASA's Mars Reconnaissance Orbiter for delayed transmission to Earth. InSight -- an acronym for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport -- will study the interior of Mars to improve understanding of the processes that formed and shaped rocky planets, including Earth. After launch, the MarCO twins and InSight will be navigated separately to Mars. Note: After thorough examination, NASA managers have decided to suspend the planned March 2016 launch of the Interior Exploration using Seismic Investigations Geodesy and Heat Transport (InSight) mission. The decision follows unsuccessful attempts to repair a leak in a section of the prime instrument in the science payload. http://photojournal.jpl.nasa.gov/catalog/PIA19389

Size Contrast for Mars CubeSat

NASA Image and Video Library

2015-06-12

The full-scale mock-up of NASA's MarCO CubeSat held by Farah Alibay, a systems engineer at NASA's Jet Propulsion Laboratory, is dwarfed by the one-half-scale model of NASA's Mars Reconnaissance Orbiter behind her. MarCO, short for Mars Cube One, is the first interplanetary use of CubeSat technologies for small spacecraft. JPL is preparing two MarCO twins for launch in March 2016. They will ride along on an Atlas V launch vehicle lifting off from Vandenberg Air Force Base, California, with NASA's next Mars lander, InSight. MarCO is a technology demonstration aspect of the InSight mission. The mock-up in the photo is in a configuration to show the deployed position of components that correspond to MarCO's two solar panels and two antennas. During launch, those components will be stowed for a total vehicle size of about 14.4 inches (36.6 centimeters) by 9.5 inches (24.3 centimeters) by 4.6 inches (11.8 centimeters). After launch, the two MarCO CubeSats and InSight will be navigated separately to Mars. The MarCO twins will fly past the planet in September 2016 just as InSight is descending through the atmosphere and landing on the surface. MarCO is a technology demonstration to relay communications from InSight to Earth during InSight's descent and landing. InSight communications during that critical period will also be recorded by NASA's Mars Reconnaissance Orbiter for delayed transmission to Earth. InSight -- an acronym for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport -- will study the interior of Mars to improve understanding of the processes that formed and shaped rocky planets, including Earth. Note: After thorough examination, NASA managers have decided to suspend the planned March 2016 launch of the Interior Exploration using Seismic Investigations Geodesy and Heat Transport (InSight) mission. The decision follows unsuccessful attempts to repair a leak in a section of the prime instrument in the science payload. http://photojournal.jpl.nasa.gov/catalog/PIA19671

InSight Final Flight Installation of Heatshield

NASA Image and Video Library

2018-04-12

In the Astrotech facility at Vandenberg Air Force Base in California, technicians and engineers place the heatshield on NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander prior to encapsulation in its payload fairing. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

At Space Launch Complex 3 at Vandenberg Air Force Base in California, NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander is positioned atop a United Launch Alliance Atlas V rocket. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Lift & Mate

NASA Image and Video Library

2018-04-23

At Space Launch Complex 3 at Vandenberg Air Force Base in California, technicians and engineers position NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander atop a United Launch Alliance Atlas V rocket. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

At Space Launch Complex 3 at Vandenberg Air Force Base in California, technicians and engineers position NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander atop a United Launch Alliance Atlas V rocket. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

At Space Launch Complex 3 at Vandenberg Air Force Base in California, NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander has been mated atop a United Launch Alliance Atlas V rocket. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

At Space l Launch Complex 3 at Vandenberg Air Force Base in California, a crane is used to lift NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander for mating atop a United Launch Alliance Atlas V rocket. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

At Space Launch Complex 3 at Vandenberg Air Force Base in California, a crane is used to lift NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander for mating atop a United Launch Alliance Atlas V rocket. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Lift & Mate

NASA Image and Video Library

2018-04-23

At Space Launch Complex 3 at Vandenberg Air Force Base in California, a crane is used to lift NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander for mating atop a United Launch Alliance Atlas V rocket. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Battery Installation

NASA Image and Video Library

2018-04-20

In the gantry at Space Launch Complex 3 at Vandenberg Air Force Base in California, technicians and engineers prepare batteries for installation in NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.