Attitude sensor alignment calibration for the solar maximum mission

NASA Technical Reports Server (NTRS)

Pitone, Daniel S.; Shuster, Malcolm D.

1990-01-01

An earlier heuristic study of the fine attitude sensors for the Solar Maximum Mission (SMM) revealed a temperature dependence of the alignment about the yaw axis of the pair of fixed-head star trackers relative to the fine pointing Sun sensor. Here, new sensor alignment algorithms which better quantify the dependence of the alignments on the temperature are developed and applied to the SMM data. Comparison with the results from the previous study reveals the limitations of the heuristic approach. In addition, some of the basic assumptions made in the prelaunch analysis of the alignments of the SMM are examined. The results of this work have important consequences for future missions with stringent attitude requirements and where misalignment variations due to variations in the temperature will be significant.

Temperature dependence of attitude sensor coalignments on the Solar Maximum Mission (SMM)

NASA Technical Reports Server (NTRS)

Pitone, D. S.; Eudell, A. H.; Patt, F. S.

1990-01-01

The temperature correlation of the relative coalignment between the fine-pointing sun sensor and fixed-head star trackers measured on the Solar Maximum Mission (SMM) is analyzed. An overview of the SMM, including mission history and configuration, is given. Possible causes of the misalignment variation are discussed, with focus placed on spacecraft bending due to solar-radiation pressure, electronic or mechanical changes in the sensors, uncertainty in the attitude solutions, and mounting-plate expansion and contraction due to thermal effects. Yaw misalignment variation from the temperature profile is assessed, and suggestions for spacecraft operations are presented, involving methods to incorporate flight measurements of the temperature-versus-alignment function and its variance in operational procedures and the spacecraft structure temperatures in the attitude telemetry record.

Vestibular and Non-vestibular Contributions to Eye Movements that Compensate for Head Rotations during Viewing of Near Targets

NASA Technical Reports Server (NTRS)

Han, Yanning H.

2006-01-01

We studied horizontal eye movements induced by en-bloc yaw rotation, over a frequency range 0.2 - 2.8 Hz, in 10 normal human subjects as they monocularly viewed a target located at their near point of focus. We measured gain and phase relationships between eye-in-head velocity and head velocity when the near target was either earth-fixed or head-fixed. During viewing of the earth-fixed near target, median gain was 1.49 (range 1.24 - 1.87) at 0.2 Hz for the group of subjects, but declined at higher frequencies, so that at 2.8 Hz median gain was 1.08 (range 0.68 - 1.67). During viewing of the head-fixed near target , median gain was 0.03 (range 0.01 - 0.10) at 0.2 Hz for the group of subjects, but increased at higher frequencies, so that at 2.8 Hz median gain was 0.71 (range 0.28 - 0.94). We estimated the vestibular contribution to these responses vestibulo-ocular reflex gain (Gvor) by applying transient head perturbations (peak acceleration> 1,000 deg/s(exp 2)) during sinusoidal rotation under the two viewing conditions. Median Gvor, estimated < 70ms after the onset of head perturbation, was 0.98 (range 0.39 - 1.42) while viewing the earth-fixed near target, and 0.97 (range 0.37 - 1.33) while viewing the head-fixed near target. For the group of subjects, 9 out of 10 subjects showed no significant difference of Gvor between the two viewing conditions ( p > 0.053 ) at all test frequencies. Since Gvor accounted for only -73% of the overall response gain during viewing of the earth-fixed target, we investigated the relative contributions of non-vestibular factors. When subjects viewed the earth-fixed target under strobe illumination, to eliminate retinal image slip information, the gain of compensatory eye movements declined compared with viewing in ambient room light. During sum-of-sine head rotations, while viewing the earth-fixed target, to Han et al./VOR during near-viewing minimize contributions from predictive mechanisms, gain also declined Nonetheless, simple superposition of smooth-pursuit tracking of sinusoidal target motion could not fully account for the overall response at higher frequencies, suggesting other nonvestibular contributions. During binocular viewing conditions when vergence angle was significantly greater than monocular viewing (p < 0.00l), the gain of compensatory eye movements did not show proportional change; indeed, gain could not be correlated with vergence angle during monocular or binocular viewing. We conclude that several separate factors contribute to generate eye rotations during sinusoidal yaw head rotations while viewing a near target; these include the VOR, visual-tracking eye movements that utilize retinal image motion, predictive eye movements and, possibly, other unidentified non-vestibular factors. For these experiments, vergence was not an important determinant of response gam.

Vestibular and Non-vestibular Contributions to Eye Movements that Compensate for Head Rotations during Viewing of Near Targets

NASA Technical Reports Server (NTRS)

Han, Yanning H.; Kumar, Arun N.; Reschke, Millard F.; Somers, Jeffrey T.; Dell'Osso, Louis F.; Leigh, R. John

2004-01-01

We studied horizontal eye movements induced by en-bloc yaw rotation, over a frequency range 0.2 - 2.8 Hz, in 10 normal human subjects as th ey monocularly viewed a target located at their near point of focus. We measured gain and phase relationships between eye-in-head velocity and head velocity when the near target was either earth-fixed or head-fixed. During viewing of the earth-fixed near target,median gain was 1.49 (range 1.24 - 1.87) at 0.2 Hz for the group of subjects, but decl ined at higher frequencies, so that at 2.8 Hz median gain was 1.08 (r ange 0.68 - 1.67). During viewing of the head-fixed near target, median gain was 0.03 (range 0.01 - 0.10) at 0.2 Hz for the group of subjec ts, but increased at higher frequencies, so that at 2.8 Hz median gai n was 0.71 (range 0.28 - 0.94). We estimated the vestibular contribution to these responses (vestibulo-ocular reflex gain, Gvor) by applyin g transient head perturbations (peak acceleration> 1,000 deg's(exp 2) ) during sinusoidal rotation under the two viewing conditions. Median Gvor, estimated < 70m after the onset of head perturbation, was 0.98 (range 0.39 - 1.42) while viewing the earth-fixed near target, and 0. 97 (range 0.37 - 1.33) while viewing the head-fixed near target. For the group of subjects, 9 out of 10 subjects showed no sigificant diff erence of Gvor between the two viewing conditions ( p > 0.053 ) at all test frequencies. Since Gvor accounted for only approximately 73% of the overall response gain during viewing of the earth-fixed target, we investigated the relative contributions of non-vestibular factors. When subjects viewed the earth-fixed target under strobe illumination , to eliminate retinal image slip information, the gain of compensato ry eye movements declined compared with viewing in ambient room light . During sum-of-sine head rotations, while viewing the earth-fixed target, to minimize contributions from predictive mechanisms, gain also declined Nonetheless, simple superposition of smooth-pursuit tracking of sinusoidal target motion could not fully account for the overall r esponse at higher frequencies, suggesting other non-vestibular contributions. During binocular viewing conditions when vergence angle was s ignificantly greater than monocular viewing (p < 0.001), this gain of compensatory eye movements did not show proportional change; indeed, gain could not be correlated with vergence angle during monocular or binocular viewing. We conclude that several separate factors contribute to generate eye rotations during sinusoidal yaw head rotations whi le viewing a near target; these include the VOR, visual-tracking eye movements that utilize retinal image motion, predictive eye movements and, possibly, other unidentified nonvestibular factors. For these experiments, vergence was not an important determinant of response gain .

Using Stars to Align a Steered Laser System for Cosmic Ray Simulation

NASA Astrophysics Data System (ADS)

Krantz, Harry; Wiencke, Lawrence

2016-03-01

Ultra high energy cosmic rays (UHECRs) are the highest energy cosmic particles with kinetic energy above 1018eV . UHECRs are detected from the air shower of secondary particles and UV florescence that results from interaction with the atmosphere. A high power UV laser beam can be used to simulate the optical signature of a UHCER air shower. The Global Light System (GLS) is a planned network of ground-based light sources including lasers to support the planned space-based Extreme Universe Space Observatory (EUSO). A portable prototype GLS laser station has been constructed at the Colorado School of Mines. Currently the laser system uses reference targets on the ground but stars can be used to better align the beam by providing a complete hemisphere of targets. In this work, a CCD camera is used to capture images of known stars through the steering head optics. The images are analyzed to find the steering head coordinates of the target star. The true coordinates of the star are calculated from the location and time of observation. A universal adjustment for the steering head is determined from the differences between the two pairs of coordinates across multiple stars. This laser system prototype will also be used for preflight tests of the ESUO Super Pressure Balloon mission.

Studies of the vestibulo-ocular reflex on STS 4, 5 and 6

NASA Technical Reports Server (NTRS)

Thornton, William E.; Pool, Sam L.; Moore, Thomas P.; Uri, John J.

1988-01-01

The vestibulo-ocular reflex (VOR) may be altered by weightlessness. Since this reflex plays a large role in visual stabilization, it was important to document any changes caused by space flight. This is a report on findings on STS-4 through 6 and is part of a larger study of neurosensory adaptation done on STS-4 through 8. Voluntary horizontal head oscillations at 1/3 Hz with amplitude of 30 deg right and left of center were recorded by a potentiometer and compared to eye position recorded by electroculography under the following conditions: eyes open, head fixed, tracking horizontal targets switched 0, 15, and 30 degrees right and left (optokinetic reflex - OKR - and calibration); eyes open and fixed on static external target with oscillation, (vestibulo ocular reflex, eyes closed - VOR EC); eyes open and wearing opaque goggles with target fixed in imagination (vestibulo-ocular reflex, eyes shaded - VOR ES); and eyes open and fixed on a head synchronized target with head oscillation (VOR suppression). No significant changes were found in voluntary head oscillation frequency or amplitude in those with (n=5), and without (n=3), space motion sickness (SMS), with phase of flight or test condition. Variations in head oscillation were too small to have produced detectable changes in test results.

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

Wu, Benjamin; Tan, Jonathan C.; Christie, Duncan

We study giant molecular cloud (GMC) collisions and their ability to trigger star cluster formation. We further develop our three-dimensional magnetized, turbulent, colliding GMC simulations by implementing star formation subgrid models. Two such models are explored: (1) “Density-Regulated,” i.e., fixed efficiency per free-fall time above a set density threshold and (2) “Magnetically Regulated,” i.e., fixed efficiency per free-fall time in regions that are magnetically supercritical. Variations of parameters associated with these models are also explored. In the non-colliding simulations, the overall level of star formation is sensitive to model parameter choices that relate to effective density thresholds. In the GMCmore » collision simulations, the final star formation rates and efficiencies are relatively independent of these parameters. Between the non-colliding and colliding cases, we compare the morphologies of the resulting star clusters, properties of star-forming gas, time evolution of the star formation rate (SFR), spatial clustering of the stars, and resulting kinematics of the stars in comparison to the natal gas. We find that typical collisions, by creating larger amounts of dense gas, trigger earlier and enhanced star formation, resulting in 10 times higher SFRs and efficiencies. The star clusters formed from GMC collisions show greater spatial substructure and more disturbed kinematics.« less

Visual Acuity Using Head-fixed Displays During Passive Self and Surround Motion

NASA Technical Reports Server (NTRS)

Wood, Scott J.; Black, F. Owen; Stallings, Valerie; Peters, Brian

2007-01-01

The ability to read head-fixed displays on various motion platforms requires the suppression of vestibulo-ocular reflexes. This study examined dynamic visual acuity while viewing a head-fixed display during different self and surround rotation conditions. Twelve healthy subjects were asked to report the orientation of Landolt C optotypes presented on a micro-display fixed to a rotating chair at 50 cm distance. Acuity thresholds were determined by the lowest size at which the subjects correctly identified 3 of 5 optotype orientations at peak velocity. Visual acuity was compared across four different conditions, each tested at 0.05 and 0.4 Hz (peak amplitude of 57 deg/s). The four conditions included: subject rotated in semi-darkness (i.e., limited to background illumination of the display), subject stationary while visual scene rotated, subject rotated around a stationary visual background, and both subject and visual scene rotated together. Visual acuity performance was greatest when the subject rotated around a stationary visual background; i.e., when both vestibular and visual inputs provided concordant information about the motion. Visual acuity performance was most reduced when the subject and visual scene rotated together; i.e., when the visual scene provided discordant information about the motion. Ranges of 4-5 logMAR step sizes across the conditions indicated the acuity task was sufficient to discriminate visual performance levels. The background visual scene can influence the ability to read head-fixed displays during passive motion disturbances. Dynamic visual acuity using head-fixed displays can provide an operationally relevant screening tool for visual performance during exposure to novel acceleration environments.

A Novel Saccadic Strategy Revealed by Suppression Head Impulse Testing of Patients with Bilateral Vestibular Loss.

PubMed

de Waele, Catherine; Shen, Qiwen; Magnani, Christophe; Curthoys, Ian S

2017-01-01

We examined the eye movement response patterns of a group of patients with bilateral vestibular loss (BVL) during suppression head impulse testing. Some showed a new saccadic strategy that may have potential for explaining how patients use saccades to recover from vestibular loss. Eight patients with severe BVL [vestibulo-ocular reflex (VOR) gains less than 0.35 and absent otolithic function] were tested. All patients were given the Dizziness Handicap Inventory and questioned about oscillopsia during abrupt head movements. Two paradigms of video head impulse testing of the horizontal VOR were used: (1) the classical head impulse paradigm [called head impulse test (HIMPs)]-fixating an earth-fixed target during the head impulse and (2) the new complementary test paradigm-fixating a head-fixed target during the head impulse (called SHIMPs). The VOR gain of HIMPs was quantified by two algorithms. During SHIMPs testing, some BVL patients consistently generated an inappropriate covert compensatory saccade during the head impulse that required a corresponding large anti-compensatory saccade at the end of the head impulse in order to obey the instructions to maintain gaze on the head-fixed target. By contrast, other BVL patients did not generate this inappropriate covert saccade and did not exhibit a corresponding anti-compensatory saccade. The latencies of the covert saccade in SHIMPs and HIMPs were similar. The pattern of covert saccades during SHIMPs appears to be related to the reduction of oscillopsia during abrupt head movements. BVL patients who did not report oscillopsia showed this unusual saccadic pattern, whereas BVL patients who reported oscillopsia did not show this pattern. This inappropriate covert SHIMPs saccade may be an objective indicator of how some patients with vestibular loss have learned to trigger covert saccades during head movements in everyday life.

Young Stars Emerge from Orion Head

NASA Image and Video Library

2007-05-17

This image from NASA's Spitzer Space Telescope shows infant stars "hatching" in the head of the hunter constellation, Orion. Astronomers suspect that shockwaves from a supernova explosion in Orion's head, nearly three million years ago, may have initiated this newfound birth . The region featured in this Spitzer image is called Barnard 30. It is located approximately 1,300 light-years away and sits on the right side of Orion's "head," just north of the massive star Lambda Orionis. Wisps of red in the cloud are organic molecules called polycyclic aromatic hydrocarbons. These molecules are formed anytime carbon-based materials are burned incompletely. On Earth, they can be found in the sooty exhaust from automobile and airplane engines. They also coat the grills where charcoal-broiled meats are cooked. This image shows infrared light captured by Spitzer's infrared array camera. Light with wavelengths of 8 and 5.8 microns (red and orange) comes mainly from dust that has been heated by starlight. Light of 4.5 microns (green) shows hot gas and dust; and light of 3.6 microns (blue) is from starlight. http://photojournal.jpl.nasa.gov/catalog/PIA09412

Young Stars Emerge from Orion's Head

NASA Technical Reports Server (NTRS)

2007-01-01

This image from NASA's Spitzer Space Telescope shows infant stars 'hatching' in the head of the hunter constellation, Orion. Astronomers suspect that shockwaves from a supernova explosion in Orion's head, nearly three million years ago, may have initiated this newfound birth

The region featured in this Spitzer image is called Barnard 30. It is located approximately 1,300 light-years away and sits on the right side of Orion's 'head,' just north of the massive star Lambda Orionis.

Wisps of red in the cloud are organic molecules called polycyclic aromatic hydrocarbons. These molecules are formed anytime carbon-based materials are burned incompletely. On Earth, they can be found in the sooty exhaust from automobile and airplane engines. They also coat the grills where charcoal-broiled meats are cooked.

This image shows infrared light captured by Spitzer's infrared array camera. Light with wavelengths of 8 and 5.8 microns (red and orange) comes mainly from dust that has been heated by starlight. Light of 4.5 microns (green) shows hot gas and dust; and light of 3.6 microns (blue) is from starlight.

Galaxy growth from redshift 5 to 0 at fixed comoving number density

NASA Astrophysics Data System (ADS)

van de Voort, Freeke

2016-10-01

Studying the average properties of galaxies at a fixed comoving number density over a wide redshift range has become a popular observational method, because it may trace the evolution of galaxies statistically. We test this method by comparing the evolution of galaxies at fixed number density and by following individual galaxies through cosmic time (z = 0-5) in cosmological, hydrodynamical simulations from the OverWhelmingly Large Simulations project. Comparing progenitors, descendants, and galaxies selected at fixed number density at each redshift, we find differences of up to a factor of 3 for galaxy and interstellar medium (ISM) masses. The difference is somewhat larger for black hole masses. The scatter in ISM mass increases significantly towards low redshift with all selection techniques. We use the fixed number density technique to study the assembly of dark matter, gas, stars, and black holes and the evolution in accretion and star formation rates. We find three different regimes for massive galaxies, consistent with observations: at high redshift the gas accretion rate dominates, at intermediate redshifts the star formation rate is the highest, and at low redshift galaxies grow mostly through mergers. Quiescent galaxies have much lower ISM masses (by definition) and much higher black hole masses, but the stellar and halo masses are fairly similar. Without active galactic nucleus (AGN) feedback, massive galaxies are dominated by star formation down to z = 0 and most of their stellar mass growth occurs in the centre. With AGN feedback, stellar mass is only added to the outskirts of galaxies by mergers and they grow inside-out.

Studies of the horizontal vestibulo-ocular reflex on STS 7 and 8

NASA Technical Reports Server (NTRS)

Thornton, William E.; Uri, John J.; Moore, Thomas P.; Pool, Sam L.

1988-01-01

Unpaced voluntary horizontal head oscillation was used to study the Vestibulo-Ocular Reflex (VOR) on Shuttle flights STS 7 and 8. Ten subjects performed head oscillations at 0.33 Hz + or - 30 deg amplitude under the followng conditions: VVOR (visual VOR), eyes open and fixed on a stationary target; VOR-EC, with eyes closed and fixed on the same target in imagination; and VOR-S (VOR suppression), with eyes open and fixed on a head-synchronized target. Effects of weightlessness, flight phase, and Space Motion Sickness (SMS) on head oscillation characteristics were examined. A significant increase in head oscillation frequency was noted inflight in subjects free from SMS. In subjects susceptible to SMS, frequency was reduced during their Symptomatic period. The data also suggest that the amplitude and peak velocity of head oscillation were reduced early inflight. No significant changes were noted in reflex gain or phase in any of the test conditions; however, there was a suggestion of an increase in VVOR and VOR-ES gain early inflight in asymptomatic subjects. A significant difference in VOR-S was found between SMS susceptible and non-susceptible subjects. There is no evidence that any changes in VOR characteristics contributed to SMS.

Pseudo-Linear Attitude Determination of Spinning Spacecraft

NASA Technical Reports Server (NTRS)

Bar-Itzhack, Itzhack Y.; Harman, Richard R.

2004-01-01

This paper presents the overall mathematical model and results from pseudo linear recursive estimators of attitude and rate for a spinning spacecraft. The measurements considered are vector measurements obtained by sun-sensors, fixed head star trackers, horizon sensors, and three axis magnetometers. Two filters are proposed for estimating the attitude as well as the angular rate vector. One filter, called the q-Filter, yields the attitude estimate as a quaternion estimate, and the other filter, called the D-Filter, yields the estimated direction cosine matrix. Because the spacecraft is gyro-less, Euler s equation of angular motion of rigid bodies is used to enable the estimation of the angular velocity. A simpler Markov model is suggested as a replacement for Euler's equation in the case where the vector measurements are obtained at high rates relative to the spacecraft angular rate. The performance of the two filters is examined using simulated data.

Natural Whisker-Guided Behavior by Head-Fixed Mice in Tactile Virtual Reality

PubMed Central

Sofroniew, Nicholas J.; Cohen, Jeremy D.; Lee, Albert K.

2014-01-01

During many natural behaviors the relevant sensory stimuli and motor outputs are difficult to quantify. Furthermore, the high dimensionality of the space of possible stimuli and movements compounds the problem of experimental control. Head fixation facilitates stimulus control and movement tracking, and can be combined with techniques for recording and manipulating neural activity. However, head-fixed mouse behaviors are typically trained through extensive instrumental conditioning. Here we present a whisker-based, tactile virtual reality system for head-fixed mice running on a spherical treadmill. Head-fixed mice displayed natural movements, including running and rhythmic whisking at 16 Hz. Whisking was centered on a set point that changed in concert with running so that more protracted whisking was correlated with faster running. During turning, whiskers moved in an asymmetric manner, with more retracted whisker positions in the turn direction and protracted whisker movements on the other side. Under some conditions, whisker movements were phase-coupled to strides. We simulated a virtual reality tactile corridor, consisting of two moveable walls controlled in a closed-loop by running speed and direction. Mice used their whiskers to track the walls of the winding corridor without training. Whisker curvature changes, which cause forces in the sensory follicles at the base of the whiskers, were tightly coupled to distance from the walls. Our behavioral system allows for precise control of sensorimotor variables during natural tactile navigation. PMID:25031397

Deep Stromvil Photometry for Star Formation in the Head of the Pelican Nebula

NASA Astrophysics Data System (ADS)

Boyle, Richard P.; J., S.; Stott, J.; J., S.; Janusz, R.; J., S.; Straizys, V.

2010-01-01

The North America and Pelican Nebulae, and specifically the dark cloud L935 contain regions of active star formation (Herbig, G. H. 1958, ApJ, 128,259). Previously we reported on Vatican telescope observations by Stromvil intermediate-band filters in a 12-arcmin field in the "Gulf of Mexico" region of L935. There we classify A, F, and G-type stars. However, the many faint K and M-type dwarf stars remain somewhat ambiguous in calibration and classification. But attaining reasonable progress, we turn to another part of L935 located near the Pelican head. This area includes the "bright rim" which is formed by dust and gas condensed by the light pressure of an unseen O-type star hidden behind the dense dark cloud. Straizys and Laugalys (2008 Baltic Astronomy, 17, 143 ) have identified this star to be one of the 2MASS objects with Av=23 mag. A few concentrations of faint stars, V 13 to 14 mag. are immersed in this dark region. Among these stars are a few known emission-line objects (T-Tauri or post T-Tauri stars). A half degree nearby are some photometric Vilnius standards we use to calibrate our new field. We call on 2MASS data for correlative information. Also the Stromvil photometry offers candidate stars for spectral observations. The aim of this study in the Vilnius and Stromvil photometric systems is to classify stars down to V = 18 mag., to confirm the existence of the young star clusters, and to determine the distance of the cloud covering the suspected hidden ionizing star.

Opportunity Science Using the Juno Magnetometer Investigation Star Trackers

NASA Astrophysics Data System (ADS)

Joergensen, J. L.; Connerney, J. E.; Bang, A. M.; Denver, T.; Oliversen, R. J.; Benn, M.; Lawton, P.

2013-12-01

The magnetometer experiment onboard Juno is equipped with four non-magnetic star tracker camera heads, two of which reside on each of the magnetometer sensor optical benches. These are located 10 and 12 m from the spacecraft body at the end of one of the three solar panel wings. The star tracker, collectively referred to as the Advanced Stellar Compass (ASC), provides high accuracy attitude information for the magnetometer sensors throughout science operations. The star tracker camera heads are pointed +/- 13 deg off the spin vector, in the anti-sun direction, imaging a 13 x 20 deg field of view every ¼ second as Juno rotates at 1 or 2 rpm. The ASC is a fully autonomous star tracker, producing a time series of attitude quaternions for each camera head, utilizing a suite of internal support functions. These include imaging capabilities, autonomous object tracking, automatic dark-sky monitoring, and related capabilities; these internal functions may be accessed via telecommand. During Juno's cruise phase, this capability can be tapped to provide unique science and engineering data available along the Juno trajectory. We present a few examples of the JUNO ASC opportunity science here. As the Juno spacecraft approached the Earth-Moon system for the close encounter with the Earth on October 9, 2013, one of the ASC camera heads obtained imagery of the Earth-Moon system while the other three remained in full science (attitude determination) operation. This enabled the first movie of the Earth and Moon obtained by a spacecraft flying past the Earth in gravity assist. We also use the many artificial satellites in orbit about the Earth as calibration targets for the autonomous asteroid detection system inherent to the ASC autonomous star tracker. We shall also profile the zodiacal dust disk, using the interstellar image data, and present the outlook for small asteroid body detection and distribution being performed during Juno's passage from Earth flyby to Jovian orbit insertion.

LOCAL TADPOLE GALAXIES

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

Elmegreen, Debra Meloy; Putko, Joseph; Dewberry, Janosz

2012-05-10

Tadpole galaxies have a giant star-forming region at the end of an elongated intensity distribution. Here we use Sloan Digital Sky Survey data to determine the ages, masses, and surface densities of the heads and tails in 14 local tadpoles selected from the Kiso and Michigan surveys of UV-bright galaxies, and we compare them to tadpoles previously studied in the Hubble Ultra Deep Field. The young stellar mass in the head scales linearly with rest-frame galaxy luminosity, ranging from {approx}10{sup 5} M{sub Sun} at galaxy absolute magnitude U = -13 mag to 10{sup 9} M{sub Sun} at U = -20more » mag. The corresponding head surface density increases from several M {sub Sun} pc{sup -2} locally to 10-100 M{sub Sun} pc{sup -2} at high redshift, and the star formation rate (SFR) per unit area in the head increases from {approx}0.01 M{sub Sun} yr{sup -1} kpc{sup -2} locally to {approx}1 M{sub Sun} yr{sup -1} kpc{sup -2} at high z. These local values are normal for star-forming regions, and the increases with redshift are consistent with other cosmological SFRs, most likely reflecting an increase in gas abundance. The tails in the local sample look like bulge-free galaxy disks. Their photometric ages decrease from several Gyr to several hundred Myr with increasing z, and their surface densities are more constant than the surface densities of the heads. The far-outer intensity profiles in the local sample are symmetric and exponential. We suggest that most local tadpoles are bulge-free galaxy disks with lopsided star formation, perhaps from environmental effects such as ram pressure or disk impacts, or from a Jeans length comparable to half the disk size.« less

Correlating Whole Brain Neural Activity with Behavior in Head-Fixed Larval Zebrafish.

PubMed

Orger, Michael B; Portugues, Ruben

2016-01-01

We present a protocol to combine behavioral recording and imaging using 2-photon laser-scanning microscopy in head-fixed larval zebrafish that express a genetically encoded calcium indicator. The steps involve restraining the larva in agarose, setting up optics that allow projection of a visual stimulus and infrared illumination to monitor behavior, and analysis of the neuronal and behavioral data.

Deriving physical parameters of unresolved star clusters. V. M 31 PHAT star clusters

NASA Astrophysics Data System (ADS)

de Meulenaer, P.; Stonkutė, R.; Vansevičius, V.

2017-06-01

Context. This study is the fifth of a series that investigates the degeneracy and stochasticity problems present in the determination of physical parameters such as age, mass, extinction, and metallicity of partially resolved or unresolved star cluster populations in external galaxies when using HST broad-band photometry. Aims: In this work we aim to derive parameters of star clusters using models with fixed and free metallicity based on the HST WFC3+ACS photometric system. The method is applied to derive parameters of a subsample of 1363 star clusters in the Andromeda galaxy observed with the HST. Methods: Following Paper III, we derive the star cluster parameters using a large grid of stochastic models that are compared to the six observed integrated broad-band WFC3+ACS magnitudes of star clusters. Results: We show that the age, mass, and extinction of the M 31 star clusters, derived assuming fixed solar metallicity, are in agreement with previous studies. We also demonstrate the ability of the WFC3+ACS photometric system to derive metallicity of star clusters older than 1 Gyr. We show that the metallicity derived using broad-band photometry of 36 massive M 31 star clusters is in good agreement with the metallicity derived using spectroscopy. Table 1 is 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/602/A112

Astrometric Jitter of the Sun as a Star

DTIC Science & Technology

2010-05-01

active, fast-rotating stars. The research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology...as the Sun is not affected by star spot noise, but the prospects for more active stars may be limited to giant planets. Subject headings: open clusters ...nearby dwarfs should be as amenable to exoplanet detection as the Sun. The aim of this paper is to determine the solar astrometric jitter directly

Star-coupled Hindmarsh-Rose neural network with chemical synapses

NASA Astrophysics Data System (ADS)

Usha, K.; Subha, P. A.

We analyze the patterns like synchrony, desynchrony, and Drum head mode in a network of Hindmarsh-Rose (HR) neurons interacting via chemical synapse in unidirectional and bidirectional star topology. A two-coupled system has been studied for synchronization by varying the coupling strength and the parameter describing the activation and inactivation of the fast ion channel. The transverse Lyapunov exponent spectrum is plotted to observe the point of transition from desynchrony to synchrony. The synchronized, desynchronized, and drum head mode regions are observed when the neurons are connected in unidirectional and bidirectional coupling configurations. A detailed analysis about the time evolution of membrane potential corresponding to each region is presented. The annihilation of synchronized region and the expansion of drum head mode region in bidirectional coupling is discussed using parameter space. Our work provides finer insight into the existence and stability of Drum head mode and is useful for designing communication networks.

al-Sufi, Abu al-Rahman (903-86)

NASA Astrophysics Data System (ADS)

Murdin, P.

2000-11-01

Persian astronomer, published works on astronomical instruments. Revised PTOLEMY's star catalog as the Book of the Constellations of the Fixed Stars, with improved magnitudes, stars named by reference to constellation figures (much copied, for example by ALFONSO X as Libros del Saber de Astronomìa), and nebulae, including the Andromeda Galaxy (M31). However, the work was not entirely original sin...

Spitzer Spectroscopy of the Transition Object TW Hya

DTIC Science & Technology

2010-02-24

results bear on our understanding of the evolutionary state of the TW Hya disk . Subject headings: (stars:) circumstellar matter — (stars:) planetary systems... protoplanetary disks — stars: pre-main sequence — (stars: individual) TW Hya 1. Introduction Spectroscopy with the Spitzer Space Telescope has...region of the disk . (2) If a planet has formed with a mass sufficient to open a gap (∼ 1MJ), gas will be cleared in the vicinity of its orbit, but gap

Frames of reference for gaze saccades evoked during stimulation of lateral intraparietal cortex.

PubMed

Constantin, A G; Wang, H; Martinez-Trujillo, J C; Crawford, J D

2007-08-01

Previous studies suggest that stimulation of lateral intraparietal cortex (LIP) evokes saccadic eye movements toward eye- or head-fixed goals, whereas most single-unit studies suggest that LIP uses an eye-fixed frame with eye-position modulations. The goal of our study was to determine the reference frame for gaze shifts evoked during LIP stimulation in head-unrestrained monkeys. Two macaques (M1 and M2) were implanted with recording chambers over the right intraparietal sulcus and with search coils for recording three-dimensional eye and head movements. The LIP region was microstimulated using pulse trains of 300 Hz, 100-150 microA, and 200 ms. Eighty-five putative LIP sites in M1 and 194 putative sites in M2 were used in our quantitative analysis throughout this study. Average amplitude of the stimulation-evoked gaze shifts was 8.67 degrees for M1 and 7.97 degrees for M2 with very small head movements. When these gaze-shift trajectories were rotated into three coordinate frames (eye, head, and body), gaze endpoint distribution for all sites was most convergent to a common point when plotted in eye coordinates. Across all sites, the eye-centered model provided a significantly better fit compared with the head, body, or fixed-vector models (where the latter model signifies no modulation of the gaze trajectory as a function of initial gaze position). Moreover, the probability of evoking a gaze shift from any one particular position was modulated by the current gaze direction (independent of saccade direction). These results provide causal evidence that the motor commands from LIP encode gaze command in eye-fixed coordinates but are also subtly modulated by initial gaze position.

Procedures for Behavioral Experiments in Head-Fixed Mice

PubMed Central

Guo, Zengcai V.; Hires, S. Andrew; Li, Nuo; O'Connor, Daniel H.; Komiyama, Takaki; Ophir, Eran; Huber, Daniel; Bonardi, Claudia; Morandell, Karin; Gutnisky, Diego; Peron, Simon; Xu, Ning-long; Cox, James; Svoboda, Karel

2014-01-01

The mouse is an increasingly prominent model for the analysis of mammalian neuronal circuits. Neural circuits ultimately have to be probed during behaviors that engage the circuits. Linking circuit dynamics to behavior requires precise control of sensory stimuli and measurement of body movements. Head-fixation has been used for behavioral research, particularly in non-human primates, to facilitate precise stimulus control, behavioral monitoring and neural recording. However, choice-based, perceptual decision tasks by head-fixed mice have only recently been introduced. Training mice relies on motivating mice using water restriction. Here we describe procedures for head-fixation, water restriction and behavioral training for head-fixed mice, with a focus on active, whisker-based tactile behaviors. In these experiments mice had restricted access to water (typically 1 ml/day). After ten days of water restriction, body weight stabilized at approximately 80% of initial weight. At that point mice were trained to discriminate sensory stimuli using operant conditioning. Head-fixed mice reported stimuli by licking in go/no-go tasks and also using a forced choice paradigm using a dual lickport. In some cases mice learned to discriminate sensory stimuli in a few trials within the first behavioral session. Delay epochs lasting a second or more were used to separate sensation (e.g. tactile exploration) and action (i.e. licking). Mice performed a variety of perceptual decision tasks with high performance for hundreds of trials per behavioral session. Up to four months of continuous water restriction showed no adverse health effects. Behavioral performance correlated with the degree of water restriction, supporting the importance of controlling access to water. These behavioral paradigms can be combined with cellular resolution imaging, random access photostimulation, and whole cell recordings. PMID:24520413

Tunable Affinity and Molecular Architecture Lead to Diverse Self-Assembled Supramolecular Structures in Thin Films

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

Hsu, Chih-Hao; Dong, Xue-Hui; Lin, Zhiwei

2015-12-03

The self-assembly behaviors of specifically designed giant surfactants are systematically studied in thin films using grazing incident X-ray and transmission electron microscopy (TEM), focusing on the effects of head surface functionalities and molecular architectures on nanostructure formation. Two molecular nanoparticles (MNPs) with different affinities, i.e., hydrophilic carboxylic acid functionalized [60]fullerene (AC60) and omniphobic fluorinated polyhedral oligomeric silsesquioxane (FPOSS), are utilized as heads of the giant surfactants. By covalently tethering these functional MNPs onto the chain end or the junction point of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymer, linear and star-like giant surfactants possess distinct molecular architectures are constructed. With fixed lengthmore » of the PEO block, the molecular weight change of the PS block originates the phase formation and transition. Due to the distinct affinity, the AC60-based giant surfactants form two-component morphologies, while three-component morphologies are found in the FPOSS-based ones. A PS block stretching parameter is introduced to characterize the PS chain conformation in different morphologies. The highly diverse self-assembly behaviors and the tunable dimensions in thin films suggest the giant surfactants could be a promising and robust platform for nanolithography applications.« less

Auditory, Vestibular and Cognitive Effects due to Repeated Blast Exposure on the Warfighter

DTIC Science & Technology

2012-10-01

Gaze Horizontal (Left and Right) Description: The primary purpose of the Gaze Horizontal subtest was to detect nystagmus when the head is fixed and...to detect nystagmus when the head is fixed and the eyes are gazing off center from the primary (straight ahead) gaze position. This test is designed...physiological target area and examiner instructions for testing): Spontaneous Nystagmus Smooth Harmonic Acceleration (.01, .08, .32, .64, 1.75

State-dependent sensorimotor processing: gaze and posture stability during simulated flight in birds.

PubMed

McArthur, Kimberly L; Dickman, J David

2011-04-01

Vestibular responses play an important role in maintaining gaze and posture stability during rotational motion. Previous studies suggest that these responses are state dependent, their expression varying with the environmental and locomotor conditions of the animal. In this study, we simulated an ethologically relevant state in the laboratory to study state-dependent vestibular responses in birds. We used frontal airflow to simulate gliding flight and measured pigeons' eye, head, and tail responses to rotational motion in darkness, under both head-fixed and head-free conditions. We show that both eye and head response gains are significantly higher during flight, thus enhancing gaze and head-in-space stability. We also characterize state-specific tail responses to pitch and roll rotation that would help to maintain body-in-space orientation during flight. These results demonstrate that vestibular sensorimotor processing is not fixed but depends instead on the animal's behavioral state.

State-dependent sensorimotor processing: gaze and posture stability during simulated flight in birds

PubMed Central

McArthur, Kimberly L.

2011-01-01

Vestibular responses play an important role in maintaining gaze and posture stability during rotational motion. Previous studies suggest that these responses are state dependent, their expression varying with the environmental and locomotor conditions of the animal. In this study, we simulated an ethologically relevant state in the laboratory to study state-dependent vestibular responses in birds. We used frontal airflow to simulate gliding flight and measured pigeons′ eye, head, and tail responses to rotational motion in darkness, under both head-fixed and head-free conditions. We show that both eye and head response gains are significantly higher during flight, thus enhancing gaze and head-in-space stability. We also characterize state-specific tail responses to pitch and roll rotation that would help to maintain body-in-space orientation during flight. These results demonstrate that vestibular sensorimotor processing is not fixed but depends instead on the animal's behavioral state. PMID:21307332

5 CFR 532.105 - Pay-fixing authority.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Pay-fixing authority. 532.105 Section 532.105 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PREVAILING RATE SYSTEMS General Provisions § 532.105 Pay-fixing authority. The head of each agency shall authorize...

Heading toward Gliese 445

NASA Image and Video Library

2013-09-12

The image taken by the Oschin Schmidt Telescope, shows the star AC +79 3888, also known as Gliese 445. NASA Voyager 1 spacecraft, which is on a trajectory out of our solar system, is headed toward an encounter with AC +79 3888 circled in red.

"Tripolar" hip arthroplasty for failed hip resurfacing: nineteen years follow-up.

PubMed

Scheerlinck, T; Casteleyn, P P

2001-10-01

The authors describe the case of a 37-year-old patient who sustained a subcapital femoral neck fracture six months after ICLH double-cup hip resurfacing. As the polyethylene acetabular resurfacing component was undamaged and well fixed, a standard femoral stem with a bipolar head was inserted. The outer diameter of the bipolar head was chosen to fit the resurfacing socket. The "tripolar" hip arthroplasty has functioned well for 19 years and was revised for aseptic cup loosening. The cemented femoral stem was still well fixed and was not revised. Although the "tripolar" hip has functioned well in our case, we believe it is not indicated for metal on metal bearings. In this case the use of an appropriate modular head with a correct head-socket clearance is preferred.

APMP Scale Comparison with Three Radiation Thermometers and Six Fixed-Point Blackbodies

NASA Astrophysics Data System (ADS)

Yamada, Y.; Shimizu, Y.; Ishii, J.

2015-08-01

New Asia Pacific Metrology Programme (APMP) comparisons of radiation thermometry standards, APMP TS-11, and -12, have recently been initiated. These new APMP comparisons cover the temperature range from to . Three radiation thermometers with central wavelengths of 1.6 , 0.9 , and 0.65 are the transfer devices for the radiation thermometer scale comparison conducted in the so-called star configuration. In parallel, a compact fixed-point blackbody furnace that houses six types of fixed-point cells of In, Sn, Zn, Al, Ag, and Cu is circulated, again in a star-type comparison, to substantiate fixed-point calibration capabilities. Twelve APMP national metrology institutes are taking part in this endeavor, in which the National Metrology Institute of Japan acts as the pilot. In this article, the comparison scheme is described with emphasis on the features of the transfer devices, i.e., the radiation thermometers and the fixed-point blackbodies. Results of preliminary evaluations of the performance and characteristic of these instruments as well as the evaluation method of the comparison results are presented.

Fixed-Abrasive Grinding of Thin-Film Recording Heads Final Report CRADA No. TC-0498-93

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

Blaedel, K. L.; Newman, C.

The goals of this project were (1) to significantly reduce the cost of manufacturing thin-film recording heads for magnetic storage media and (2) to meet the stringent dimensional tolerances required for heads in the next generation high-density disc drives.

Collisionless relaxation in spiral galaxy models

NASA Technical Reports Server (NTRS)

Hohl, F.

1974-01-01

The increase in random kinetic energy of stars by rapidly fluctuating gravitational fields (collisionless or violent relaxation) in disk galaxy models is investigated for three interaction potentials of the stars corresponding to (1) point stars, (2) rod stars of length 2 kpc, and (3) uniform density spherical stars of radius 2 kpc. To stabilize the galaxy against the large scale bar forming instability, a fixed field corresponding to a central core or halo component of stars was added with the stars containing at most 20 percent of the total mass of the galaxy. Considerable heating occurred for both the point stars and the rod stars, whereas the use of spherical stars resulted in a very low heating rate. The use of spherical stars with the resulting low heating rate will be desirable for the study of large scale galactic stability or density wave propagation, since collective heating effects will no longer mask the phenomena under study.

The Constant Average Relationship Between Dust-obscured Star Formation and Stellar Mass from z=0 to z=2.5

NASA Astrophysics Data System (ADS)

Whitaker, Katherine E.; Pope, Alexandra; Cybulski, Ryan; Casey, Caitlin M.; Popping, Gergo; Yun, Min; 3D-HST Collaboration

2018-01-01

The total star formation budget of galaxies consists of the sum of the unobscured star formation, as observed in the rest-frame ultraviolet (UV), together with the obscured component that is absorbed and re-radiated by dust grains in the infrared. We explore how the fraction of obscured star formation depends (SFR) and stellar mass for mass-complete samples of galaxies at 0 < z < 2.5. We combine GALEX and WISE photometry for SDSS-selected galaxies with the 3D-HST treasury program and Spitzer/MIPS 24μm photometry in the well-studied 5 extragalactic CANDELS fields. We find a strong dependence of the fraction of obscured star formation (f_obscured=SFR_IR/SFR_UV+IR) on stellar mass, with remarkably little evolution in this fraction with redshift out to z=2.5. 50% of star formation is obscured for galaxies with log(M/M⊙)=9.4 although unobscured star formation dominates the budget at lower masses, there exists a tail of low mass extremely obscured star-forming galaxies at z > 1. For log(M/M⊙)>10.5, >90% of star formation is obscured at all redshifts. We also show that at fixed total SFR, f_obscured is lower at higher redshift. At fixed mass, high-redshift galaxies are observed to have more compact sizes and much higher star formation rates, gas fractions and hence surface densities (implying higher dust obscuration), yet we observe no redshift evolution in f_obscured with stellar mass. This poses a challenge to theoretical models to reproduce, where the observed compact sizes at high redshift seem in tension with lower dust obscuration.

The Constant Average Relationship between Dust-obscured Star Formation and Stellar Mass from z = 0 to z = 2.5

NASA Astrophysics Data System (ADS)

Whitaker, Katherine E.; Pope, Alexandra; Cybulski, Ryan; Casey, Caitlin M.; Popping, Gergö; Yun, Min S.

2017-12-01

The total star formation budget of galaxies consists of the sum of the unobscured star formation, as observed in the rest-frame ultraviolet (UV), together with the obscured component that is absorbed and re-radiated by dust grains in the infrared. We explore how the fraction of obscured star formation depends on stellar mass for mass-complete samples of galaxies at 0< z< 2.5. We combine GALEX and WISE photometry for SDSS-selected galaxies with the 3D-HST treasury program and Spitzer/MIPS 24 μm photometry in the well-studied five extragalactic Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS) fields. We find a strong dependence of the fraction of obscured star formation (f obscured = SFRIR/SFRUV+IR) on stellar mass, with remarkably little evolution in this fraction with redshift out to z = 2.5. 50% of star formation is obscured for galaxies with log(M/M ⊙) = 9.4 although unobscured star formation dominates the budget at lower masses, there exists a tail of low-mass, extremely obscured star-forming galaxies at z> 1. For log(M/M ⊙) > 10.5, >90% of star formation is obscured at all redshifts. We also show that at fixed total SFR, {f}{obscured} is lower at higher redshift. At fixed mass, high-redshift galaxies are observed to have more compact sizes and much higher star formation rates, gas fractions, and hence surface densities (implying higher dust obscuration), yet we observe no redshift evolution in {f}{obscured} with stellar mass. This poses a challenge to theoretical models, where the observed compact sizes at high redshift seem in tension with lower dust obscuration.

The History of Variable Stars: A Fresh Look

NASA Astrophysics Data System (ADS)

Hatch, R. A.

2012-06-01

(Abstract only) For historians of astronomy, variable stars are important for a simple reason - stars change. But good evidence suggests this is a very modern idea. Over the millennia, our species has viewed stars as eternal and unchanging, forever fixed in time and space - indeed, the Celestial Dance was a celebration of order, reason, and stability. But everything changed in the period between Copernicus and Newton. According to tradition, two New Stars announced the birth of the New Science. Blazing across the celestial stage, Tycho's Star (1572) and Kepler's Star (1604) appeared dramatically - and just as unexpectedly - disappeared forever. But variable stars were different. Mira Ceti, the oldest, brightest, and most controversial variable star, was important because it appeared and disappeared again and again. Mira was important because it did not go away. The purpose of this essay is to take a fresh look at the history of variable stars. In re-thinking the traditional narrative, I begin with the first sightings of David Fabricius (1596) and his contemporaries - particularly Hevelius (1662) and Boulliau (1667) - to new traditions that unfolded from Newton and Maupertuis to Herschel (1780) and Pigott (1805). The essay concludes with important 19th-century developments, particularly by Argelander (1838), Pickering (1888), and Lockyer (1890). Across three centuries, variable stars prompted astronomers to re-think all the ways that stars were no longer "fixed." New strategies were needed. Astronomers needed to organize, to make continuous observations, to track changing magnitudes, and to explain stellar phases. Importantly - as Mira suggested from the outset - these challenges called for an army of observers with the discipline of Spartans. But recruiting that army required a strategy, a set of theories with shared expectations. Observation and theory worked hand-in-hand. In presenting new historical evidence from neglected printed sources and unpublished manuscripts, this essay aims to offer a fresh look at the history of variable stars.

The Radio-X-ray Relation in Cool Stars: Are We Headed Toward a Divorce?

NASA Astrophysics Data System (ADS)

Forbrich, J.; Wolk, S. J.; Güdel, M.; Benz, A.; Osten, R.; Linsky, J. L.; McLean, M.; Loinard, L.; Berger, E.

2011-12-01

This splinter session was devoted to reviewing our current knowledge of correlated X-ray and radio emission from cool stars in order to prepare for new large radio observatories such as the EVLA. A key interest was to discuss why the X-ray and radio luminosities of some cool stars are in clear breach of a correlation that holds for other active stars, the so-called Güdel-Benz relation. This article summarizes the contributions whereas the actual presentations can be accessed on the splinter website.

Analysis of advanced solid rocket motor ignition phenomena

NASA Technical Reports Server (NTRS)

Foster, Winfred A., Jr.; Jenkins, Rhonald M.

1995-01-01

This report presents the results obtained from an experimental analysis of the flow field in the slots of the star grain section in the head-end of the advanced solid rocket motor during the ignition transient. This work represents an extension of the previous tests and analysis to include the effects of using a center port in conjunction with multiple canted igniter ports. The flow field measurements include oil smear data on the star slot walls, pressure and heat transfer coefficient measurements on the star slot walls and velocity measurements in the star slot.

Comparison of two on-orbit attitude sensor alignment methods

NASA Technical Reports Server (NTRS)

Krack, Kenneth; Lambertson, Michael; Markley, F. Landis

1990-01-01

Compared here are two methods of on-orbit alignment of vector attitude sensors. The first method uses the angular difference between simultaneous measurements from two or more sensors. These angles are compared to the angular differences between the respective reference positions of the sensed objects. The alignments of the sensors are adjusted to minimize the difference between the two sets of angles. In the second method, the sensor alignment is part of a state vector that includes the attitude. The alignments are adjusted along with the attitude to minimize all observation residuals. It is shown that the latter method can result in much less alignment uncertainty when gyroscopes are used for attitude propagation during the alignment estimation. The additional information for this increased accuracy comes from knowledge of relative attitude obtained from the spacecraft gyroscopes. The theoretical calculations of this difference in accuracy are presented. Also presented are numerical estimates of the alignment uncertainties of the fixed-head star trackers on the Extreme Ultraviolet Explorer spacecraft using both methods.

An analysis of the Kalman filter in the Gamma Ray Observatory (GRO) onboard attitude determination subsystem

NASA Technical Reports Server (NTRS)

Snow, Frank; Harman, Richard; Garrick, Joseph

1988-01-01

The Gamma Ray Observatory (GRO) spacecraft needs a highly accurate attitude knowledge to achieve its mission objectives. Utilizing the fixed-head star trackers (FHSTs) for observations and gyroscopes for attitude propagation, the discrete Kalman Filter processes the attitude data to obtain an onboard accuracy of 86 arc seconds (3 sigma). A combination of linear analysis and simulations using the GRO Software Simulator (GROSS) are employed to investigate the Kalman filter for stability and the effects of corrupted observations (misalignment, noise), incomplete dynamic modeling, and nonlinear errors on Kalman filter. In the simulations, on-board attitude is compared with true attitude, the sensitivity of attitude error to model errors is graphed, and a statistical analysis is performed on the residuals of the Kalman Filter. In this paper, the modeling and sensor errors that degrade the Kalman filter solution beyond mission requirements are studied, and methods are offered to identify the source of these errors.

Subcellular Organization of CaMKII in Rat Hippocampal Pyramidal Neurons

PubMed Central

Ding, Jin-Dong; Kennedy, Mary B.; Weinberg, Richard J.

2015-01-01

Calcium/calmodulin-dependent protein kinase II (CaM-KII) plays a key role in N-methyl-D-aspartate (NMDA) receptor-dependent long-term synaptic plasticity; its location is critical for signal transduction, and may provide clues that further elucidate its function. We therefore examined the subcellular localization of CaMKII in CA1 stratum radiatum of adult rat hippocampus, by using immuno-electron microscopy after chemical fixation. When tissue was fixed quickly, the concentration of CaMKIIα (assessed by pre-embedding immunogold) was significantly higher in dendritic shafts than in spine heads. However, when tissue was fixed 5 minutes after perfusion with normal saline, the density of labeling decreased in dendritic shaft while increasing in spine heads, implying rapid translocation into the spine during brief perimortem stress. Likewise, in quickly fixed tissue, CaMKII within spine heads was found at comparable concentrations in the “proximal” half (adjacent to the spine neck) and the “distal” half (containing the postsynaptic density [PSD]), whereas after delayed fixation, label density increased in the distal side of the spine head, suggesting that CaMKII within the spine head moves toward the PSD during this interval. To estimate its distribution at the synapse in vivo, we performed postembedding immunogold staining for CaMKII in quick-fixed tissue, and found that the enzyme did not concentrate primarily within the central matrix of the PSD. Instead, labeling density peaked ∼40 nm inside the postsynaptic membrane, at the cytoplasmic fringe of the PSD. Labeling within 25 nm of the postsynaptic membrane concentrated at the lateral edge of the synapse. This lateral “PSD core” pool of CaMKII may play a special role in synaptic plasticity. PMID:23749614

Quaternion-Based Unscented Kalman Filter for Accurate Indoor Heading Estimation Using Wearable Multi-Sensor System

PubMed Central

Yuan, Xuebing; Yu, Shuai; Zhang, Shengzhi; Wang, Guoping; Liu, Sheng

2015-01-01

Inertial navigation based on micro-electromechanical system (MEMS) inertial measurement units (IMUs) has attracted numerous researchers due to its high reliability and independence. The heading estimation, as one of the most important parts of inertial navigation, has been a research focus in this field. Heading estimation using magnetometers is perturbed by magnetic disturbances, such as indoor concrete structures and electronic equipment. The MEMS gyroscope is also used for heading estimation. However, the accuracy of gyroscope is unreliable with time. In this paper, a wearable multi-sensor system has been designed to obtain the high-accuracy indoor heading estimation, according to a quaternion-based unscented Kalman filter (UKF) algorithm. The proposed multi-sensor system including one three-axis accelerometer, three single-axis gyroscopes, one three-axis magnetometer and one microprocessor minimizes the size and cost. The wearable multi-sensor system was fixed on waist of pedestrian and the quadrotor unmanned aerial vehicle (UAV) for heading estimation experiments in our college building. The results show that the mean heading estimation errors are less 10° and 5° to multi-sensor system fixed on waist of pedestrian and the quadrotor UAV, respectively, compared to the reference path. PMID:25961384

A cost-effectiveness analysis of fixed-combination therapies in patients with open-angle glaucoma: a European perspective.

PubMed

Hommer, A; Wickstrøm, J; Friis, M M; Steeds, C; Thygesen, J; Ferreras, A; Gouws, P; Buchholz, P

2008-04-01

To compare the efficacy and cost implications of the use of the intraocular pressure-lowering prostaglandin analogues bimatoprost, travoprost, and latanoprost as fixed-combination therapies with timolol, a beta-adrenergic receptor antagonist. A decision analytic cost-effectiveness model was constructed. Since no head-to-head studies comparing the three treatment options exist, the analysis was based on an indirect comparison. Hence, the model was based on efficacy data from five randomized, controlled, clinical studies. The studies were comparable with respect to study design, time horizon, patient population and type of end point presented. The measure of effectiveness was the percentage reduction of the intraocular pressure level from baseline. The cost evaluated was the cost of medication and clinical visits to the ophthalmologist. All drug costs were market prices inclusive of value-added tax, and visit costs were priced using official physician fees. Cost-effectiveness analyses were carried out in five European countries: Spain, Italy, United Kingdom, Norway and Sweden. The time horizon for the analyses was 3 months. The analysis showed that fixed-combination bimatoprost/timolol was more effective and less costly than fixed-combination travoprost/timolol and fixed-combination latanoprost/timolol in three out of the five countries analyzed. In two countries, bimatoprost/timolol was less costly than latanoprost/timolol, and cost the same as travoprost/timolol. This cost-effectiveness analysis showed that the fixed combination of bimatoprost 0.03%/timolol 0.5% administered once daily was a cost-effective treatment option for patients with primary open-angle glaucoma. This study was limited by available clinical data: without a head-to-head trial, indirect comparisons were necessary. In the United Kingdom, Sweden, Norway, Italy, and Spain, from a health service viewpoint, bimatoprost/timolol was a slightly more effective as well as less costly treatment strategy when compared to both travoprost/timolol and latanoprost/timolol.

Demonstration of variable speed permanent magnet generator at small, low-head hydro site

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

Brown Kinloch, David

Small hydro developers face a limited set of bad choices when choosing a generator for a small low-head hydro site. Direct drive synchronous generators are expensive and technically complex to install. Simpler induction generators are higher speed, requiring a speed increaser, which results in inefficiencies and maintenance problems. In addition, both induction and synchronous generators turn at a fixed speed, causing the turbine to run off its peak efficiency curve whenever the available head is different than the designed optimum head.The solution to these problems is the variable speed Permanent Magnet Generators (PMG). At the Weisenberger Mill in Midway, KY,more » a variable speed Permanent Magnet Generator has been installed and demonstrated. This new PMG system replaced an existing induction generator that had a HTD belt drive speed increaser system. Data was taken from the old generator before it was removed and compared to data collected after the PMG system was installed. The new variable speed PMG system is calculated to produce over 96% more energy than the old induction generator system during an average year. This significant increase was primarily due to the PMG generator operating at the correct speed at the maximum head, and the ability for the PMG generator to reduce its speed to lower optimum speeds as the stream flow increased and the net head decreased.This demonstration showed the importance of being able to adjust the speed of fixed blade turbines. All fixed blade turbines with varying net heads could achieve higher efficiencies if the speed can be matched to the optimum speed as the head changes. In addition, this demonstration showed that there are many potential efficiencies that could be realized with variable speed technology at hydro sites where mismatched turbine and generator speeds result in lower power output, even at maximum head. Funding for this project came from the US Dept. of Energy, through Award Number DE-EE0005429.« less

The Contribution of Head Movement to the Externalization and Internalization of Sounds

PubMed Central

Brimijoin, W. Owen; Boyd, Alan W.; Akeroyd, Michael A.

2013-01-01

Background When stimuli are presented over headphones, they are typically perceived as internalized; i.e., they appear to emanate from inside the head. Sounds presented in the free-field tend to be externalized, i.e., perceived to be emanating from a source in the world. This phenomenon is frequently attributed to reverberation and to the spectral characteristics of the sounds: those sounds whose spectrum and reverberation matches that of free-field signals arriving at the ear canal tend to be more frequently externalized. Another factor, however, is that the virtual location of signals presented over headphones moves in perfect concert with any movements of the head, whereas the location of free-field signals moves in opposition to head movements. The effects of head movement have not been systematically disentangled from reverberation and/or spectral cues, so we measured the degree to which movements contribute to externalization. Methodology/Principal Findings We performed two experiments: 1) Using motion tracking and free-field loudspeaker presentation, we presented signals that moved in their spatial location to match listeners’ head movements. 2) Using motion tracking and binaural room impulse responses, we presented filtered signals over headphones that appeared to remain static relative to the world. The results from experiment 1 showed that free-field signals from the front that move with the head are less likely to be externalized (23%) than those that remain fixed (63%). Experiment 2 showed that virtual signals whose position was fixed relative to the world are more likely to be externalized (65%) than those fixed relative to the head (20%), regardless of the fidelity of the individual impulse responses. Conclusions/Significance Head movements play a significant role in the externalization of sound sources. These findings imply tight integration between binaural cues and self motion cues and underscore the importance of self motion for spatial auditory perception. PMID:24312677

'Witch Head' Brews Baby Stars

NASA Image and Video Library

2017-12-08

A witch appears to be screaming out into space in this new image from NASA's Wide-Field Infrared Survey Explorer, or WISE. The infrared portrait shows the Witch Head nebula, named after its resemblance to the profile of a wicked witch. Astronomers say the billowy clouds of the nebula, where baby stars are brewing, are being lit up by massive stars. Dust in the cloud is being hit with starlight, causing it to glow with infrared light, which was picked up by WISE's detectors. The Witch Head nebula is estimated to be hundreds of light-years away in the Orion constellation, just off the famous hunter's knee. WISE was recently "awakened" to hunt for asteroids in a program called NEOWISE. The reactivation came after the spacecraft was put into hibernation in 2011, when it completed two full scans of the sky, as planned. Image credit: NASA/JPL-Caltech NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

A new saccadic indicator of peripheral vestibular function based on the video head impulse test

PubMed Central

MacDougall, Hamish G.; McGarvie, Leigh A.; Rogers, Stephen J.; Manzari, Leonardo; Burgess, Ann M.; Curthoys, Ian S.; Weber, Konrad P.

2016-01-01

Objective: While compensatory saccades indicate vestibular loss in the conventional head impulse test paradigm (HIMP), in which the participant fixates an earth-fixed target, we investigated a complementary suppression head impulse paradigm (SHIMP), in which the participant is fixating a head-fixed target to elicit anticompensatory saccades as a sign of vestibular function. Methods: HIMP and SHIMP eye movement responses were measured with the horizontal video head impulse test in patients with unilateral vestibular loss, patients with bilateral vestibular loss, and in healthy controls. Results: Vestibulo-ocular reflex gains showed close correlation (R2 = 0.97) with slightly lower SHIMP than HIMP gains (mean gain difference 0.06 ± 0.05 SD, p < 0.001). However, the 2 paradigms produced complementary catch-up saccade patterns: HIMP elicited compensatory saccades in patients but rarely in controls, whereas SHIMP elicited large anticompensatory saccades in controls, but smaller or no saccades in bilateral vestibular loss. Unilateral vestibular loss produced covert saccades in HIMP, but later and smaller saccades in SHIMP toward the affected side. Cumulative HIMP and SHIMP saccade amplitude differentiated patients from controls with high sensitivity and specificity. Conclusions: While compensatory saccades indicate vestibular loss in conventional HIMP, anticompensatory saccades in SHIMP using a head-fixed target indicate vestibular function. SHIMP saccades usually appear later than HIMP saccades, therefore being more salient to the naked eye and facilitating vestibulo-ocular reflex gain measurements. The new paradigm is intuitive and easy to explain to patients, and the SHIMP results complement those from the standard video head impulse test. Classification of evidence: This case-control study provides Class III evidence that SHIMP accurately identifies patients with unilateral or bilateral vestibulopathies. PMID:27251884

Research study on neck injury lessening with active head restraint using human body FE model.

PubMed

Kitagawa, Yuichi; Yasuki, Tsuyoshi; Hasegawa, Junji

2008-12-01

The objective of this study is to examine the effectiveness of the active head restraint system in reducing neck injury risk of car occupants in low-speed rear impacts. A human body FE model "THUMS" was used to simulate head and neck kinematics of the occupant and to evaluate loading to the neck. Joint capsule strain was calculated to predict neck injury risk as well as NIC. The validity of the model was confirmed comparing its mechanical responses to those in human subjects in the literatures. Seat FE models were also prepared representing one with a fixed head restraint and the other one with an active head restraint system. The active head restraint system was designed to move the head restraint forward and upward when the lower unit was lower unit was loaded by the pelvis. Rear impact simulations were performed assuming a triangular acceleration pulse at a delta-V of 25 km/h. The model reproduced similar head and neck motions to those measured in the human volunteer test, except for active muscular responses. The calculated joint capsule strain also showed a good match with those of PMHS tests in the literature. A rear-impact simulation was conducted using the model with the fixed head restraint. The result revealed that NIC was strongly correlated with the relative acceleration between the head and the torso and that its maximum peak appeared when the head contacted the head restraint. It was also found that joint capsule strain grew in later timing synchronizing with the relative displacement. Another simulation with the active head restraint system showed that both NIC and joint capsule strain were lowered owing to the forward and upward motion of the head restraint. A close investigation of the vertebral motion indicated that the active head restraint reduced the magnitude of shear deformation in the facet joint, which contributed to the strain growth in the fixed head restraint case. Rear-impact simulations were conducted using a human body FE model, THUMS, representing an average-size male occupant. The cervical system including the facet joint capsules was incorporated to the model. The validity of the model was examined comparing its mechanical responses to those in the literature such as the whole body motion of the volunteer subject and the vertebral motion in the PMHS tests. Rear-impact simulations were conducted using the validated THUMS model and two prototype seat models; one had a fixed head restraint and the other one was equipped with an active head restraint system. The active head restraint system works moving the head restraint forward and upward when the lower unit is loaded by the pelvis. The head and neck kinematics and responses were analyzed from the simulation results. The force and acceleration rose at the pelvis first, followed by T1 and the head. The early timing of force rise and its magnitude indicated that the pelvis force was a good trigger for the active head restraint system. The results showed that the head was supported earlier in a case with the active head restraint system, and both NIC and joint capsule strain were lowered. The study also analyzed the mechanism of strain growth in the joint capsules. Relatively greater strain was observed in the direction of the facet joint surface, which was around 45 degrees inclined to the spinal column. The forward and upward motion of the active head restraint were aligned with the direction of the joint deformation and contributed to lower strain in the joint capsules. The results indicated that the active head restraint could help reduce the neck injury risk not only by supporting the head at an early timing but also through its trajectory stopping the joint deformation.

STAR Au + Au Fixed Target Results

NASA Astrophysics Data System (ADS)

Meehan, Kathryn; STAR Collaboration

2015-10-01

The RHIC Beam Energy Scan (BES) program was proposed to look for the turn-off of signatures of the quark gluon plasma (QGP), search for a possible QCD critical point, and study the nature of the phase transition between hadronic and partonic matter. The results from the NA49 experiment at CERN have been used to claim that the onset of deconfinement occurs at a collision energy around a center-of-mass energy of 7 GeV, the low end of the BES range. Data from lower energies are needed to test if this onset occurs. The goal of the STAR Fixed-Target Program is to extend the collision energy range in BES II with the same detector to energies that are likely below the onset of deconfinement. Currently, STAR has inserted a gold target into the beam pipe and conducted test runs at center-of-mass energies 3.9 and 4.5 GeV. Tests have been done with both Au and Al beams. First physics results from a Coulomb analysis of Au + Au fixed-target collisions, which are found to be consistent with previous experiments, will be presented. These results demonstrate that STAR has good particle identification capabilities in this novel detector setup. Furthermore, the Coulomb potential, which is sensitive to the Z of the projectile and degree of baryonic stopping, will be compared with published results from the AGS. This material is based upon work supported by the National Science Foundation under Grant No. 1068833.

Resolution convergence in cosmological hydrodynamical simulations using adaptive mesh refinement

NASA Astrophysics Data System (ADS)

Snaith, Owain N.; Park, Changbom; Kim, Juhan; Rosdahl, Joakim

2018-06-01

We have explored the evolution of gas distributions from cosmological simulations carried out using the RAMSES adaptive mesh refinement (AMR) code, to explore the effects of resolution on cosmological hydrodynamical simulations. It is vital to understand the effect of both the resolution of initial conditions (ICs) and the final resolution of the simulation. Lower initial resolution simulations tend to produce smaller numbers of low-mass structures. This will strongly affect the assembly history of objects, and has the same effect of simulating different cosmologies. The resolution of ICs is an important factor in simulations, even with a fixed maximum spatial resolution. The power spectrum of gas in simulations using AMR diverges strongly from the fixed grid approach - with more power on small scales in the AMR simulations - even at fixed physical resolution and also produces offsets in the star formation at specific epochs. This is because before certain times the upper grid levels are held back to maintain approximately fixed physical resolution, and to mimic the natural evolution of dark matter only simulations. Although the impact of hold-back falls with increasing spatial and IC resolutions, the offsets in the star formation remain down to a spatial resolution of 1 kpc. These offsets are of the order of 10-20 per cent, which is below the uncertainty in the implemented physics but are expected to affect the detailed properties of galaxies. We have implemented a new grid-hold-back approach to minimize the impact of hold-back on the star formation rate.

Unexplained head tilt following surgical treatment of congenital esotropia: a postural manifestation of dissociated vertical divergence

PubMed Central

Brodsky, M C; Jenkins, R; Nucci, P

2004-01-01

Background: Strabismus surgery for congenital esotropia can be complicated by the development of a postoperative head tilt. Purpose: To determine the pathophysiology of acquired head tilting following horizontal realignment of the eyes in children with congenital esotropia. Materials and methods: Retrospective analysis of nine children with congenital esotropia who developed unexplained head tilts following horizontal realignment of the eyes. Results: Shortly after strabismus surgery, each child developed a head tilt in association with asymmetrical dissociated vertical divergence (DVD). Five children maintained a head tilt toward the side of the fixing eye (group 1), which did not serve to control the DVD. Four children maintained a head tilt toward the side of the hyperdeviating eye, which served to control the DVD (group 2). Children in group 2 had earlier horizontal muscle surgery and developed better stereopsis than those in group 1, suggesting that the higher degree of single binocular vision and stereopsis in these children may have led to a compensatory torticollis to control an asymmetrical DVD. Conclusions: The onset of an unexpected head tilt after congenital esotropia surgery is usually a postural manifestation of asymmetrical DVD. In this setting, a head tilt toward the side of the fixing eye corresponds with a postural manifestation of the underlying central vestibular imbalance that produces DVD, while a head tilt toward the side of the hyperdeviating eye serves to counteract the hyperdeviation and stabilise binocular vision. PMID:14736789

Postural control and head stability during natural gaze behaviour in 6- to 12-year-old children.

PubMed

Schärli, A M; van de Langenberg, R; Murer, K; Müller, R M

2013-06-01

We investigated how the influence of natural exploratory gaze behaviour on postural control develops from childhood into adulthood. In a cross-sectional design, we compared four age groups: 6-, 9-, 12-year-olds and young adults. Two experimental trials were performed: quiet stance with a fixed gaze (fixed) and quiet stance with natural exploratory gaze behaviour (exploratory). The latter was elicited by having participants watch an animated short film on a large screen in front of them. 3D head rotations in space and centre of pressure (COP) excursions on the ground plane were measured. Across conditions, both head rotation and COP displacement decreased with increasing age. Head movement was greater in the exploratory condition in all age groups. In all children-but not in adults-COP displacement was markedly greater in the exploratory condition. Bivariate correlations across groups showed highly significant positive correlations between COP displacement in ML direction and head rotation in yaw, roll, and pitch in both conditions. The regularity of COP displacements did not show a clear developmental trend, which indicates that COP dynamics were qualitatively similar across age groups. Together, the results suggest that the contribution of head movement to eye-head saccades decreases with age and that head instability-in part resulting from such gaze-related head movements-is an important limiting factor in children's postural control. The lack of head stabilisation might particularly affect children in everyday activities in which both postural control and visual exploration are required.

Adjustment of saccade characteristics during head movements.

NASA Technical Reports Server (NTRS)

Morasso, P.; Bizzi, E.; Dichgans, J.

1973-01-01

Saccade characteristics have been studied during coordinated eye-head movements in monkeys. Amplitude, duration, and peak velocity of saccades with head turning were compared with saccades executed while the head was artificially restrained. The results indicate that the saccade characteristics are modulated as a function of head movement, hence the gaze movement (eye+head) exactly matches saccades with head fixed. Saccade modulation is achieved by way of negative vestibulo-ocular feedback. The neck proprioceptors, because of their longer latency, are effective only if the head starts moving prior to the onset of saccade. It is concluded that saccades make with head turning are not 'ballistic' movements because their trajectory is not entirely predetermined by a central command.

Prediction of the body rotation-induced torques on the arm during reaching movements: evidence from a proprioceptively deafferented subject.

PubMed

Guillaud, Etienne; Simoneau, Martin; Blouin, Jean

2011-06-01

Reaching for a target while rotating the trunk generates substantial Coriolis and centrifugal torques that push the arm in the opposite direction of the rotations. These torques rarely perturb movement accuracy, suggesting that they are compensated for during the movement. Here we tested whether signals generated during body motion (e.g., vestibular) can be used to predict the torques induced by the body rotation and to modify the motor commands accordingly. We asked a deafferented subject to reach for a memorized visual target in darkness. At the onset of the reaching, the patient was rotated 25° or 40° in the clockwise or the counterclockwise directions. During the rotation, the patient's head remained either fixed in space (Head-Fixed condition) or fixed on the trunk (Head Rotation condition). At the rotation onset, the deafferented patient's hand largely deviated from the mid-sagittal plane in both conditions. The hand deviations were compensated for in the Head Rotation condition only. These results highlight the computational faculty of the brain and show that body rotation-related information can be processed for predicting the consequence of the rotation dynamics on the reaching arm movements. Copyright © 2011 Elsevier Ltd. All rights reserved.

Station Keeping of Small Outboard-Powered Boats

NASA Technical Reports Server (NTRS)

Fisher, A. D.; VanZwieten, J. H., Jr.; VanZwieten, T. S.

2010-01-01

Three station keeping controllers have been developed which work to minimize displacement of a small outboard-powered vessel from a desired location. Each of these three controllers has a common initial layer that uses fixed-gain feedback control to calculate the desired heading of the vessel. A second control layer uses a common fixed-gain feedback controller to calculate the net forward thrust, one of two algorithms for controlling engine angle (Fixed-Gain Proportional-integral-derivative (PID) or PID with Adaptively Augmented Gains), and one of two algorithms for differential throttle control (Fixed-Gain PID and PID with Adaptive Differential Throttle gains), which work together to eliminate heading error. The three selected controllers are evaluated using a numerical simulation of a 33-foot center console vessel with twin outboards that is subject to wave, wind, and current disturbances. Each controller is tested for its ability to maintain position in the presence of three sets of environmental disturbances. These algorithms were tested with current velocity of 1.5 m/s, significant wave height of 0.5 m, and wind speeds of 2, 5, and 10 m/s. These values were chosen to model conditions a small vessel may experience in the Gulf Stream off of Fort Lauderdale. The Fixed-gain PID controller progressively got worse as wind speeds increased, while the controllers using adaptive methodologies showed consistent performance over all weather conditions and decreased heading error by as much as 20%. Thus, enhanced robustness to environmental changes has been gained by using an adaptive algorithm.

Virtual reality flight control display with six-degree-of-freedom controller and spherical orientation overlay

NASA Technical Reports Server (NTRS)

Beckman, Brian C. (Inventor)

1995-01-01

A virtual reality flight control system displays to the pilot the image of a scene surrounding a vehicle or pod having six degrees of freedom of acceleration or velocity control by the pilot and traveling through inertial space, the image itself including a superimposed figure providing the pilot an instant reference of orientation consisting of superimposed sets of geometric figures whose relative orientations provide the pilot an instantaneous feel or sense of orientation changes with respect to some fixed coordinate system. They include a first set of geometric figures whose orientations are fixed to the pilot's vehicle and a second set of geometric figures whose orientations are fixed with respect to a fixed or interstellar coordinate system. The first set of figures is a first set of orthogonal great circles about the three orthogonal axes of the flight vehicle or pod and centered at and surrounding the pilot's head, while the second set of figures is a second set of orthogonal great circles about the three orthogonal axes of a fixed or interstellar coordinate system, also centered at and surrounding the pilot's head.

Brain stem omnipause neurons and the control of combined eye-head gaze saccades in the alert cat.

PubMed

Paré, M; Guitton, D

1998-06-01

When the head is unrestrained, rapid displacements of the visual axis-gaze shifts (eye-re-space)-are made by coordinated movements of the eyes (eye-re-head) and head (head-re-space). To address the problem of the neural control of gaze shifts, we studied and contrasted the discharges of omnipause neurons (OPNs) during a variety of combined eye-head gaze shifts and head-fixed eye saccades executed by alert cats. OPNs discharged tonically during intersaccadic intervals and at a reduced level during slow perisaccadic gaze movements sometimes accompanying saccades. Their activity ceased for the duration of the saccadic gaze shifts the animal executed, either by head-fixed eye saccades alone or by combined eye-head movements. This was true for all types of gaze shifts studied: active movements to visual targets; passive movements induced by whole-body rotation or by head rotation about stationary body; and electrically evoked movements by stimulation of the caudal part of the superior colliculus (SC), a central structure for gaze control. For combined eye-head gaze shifts, the OPN pause was therefore not correlated to the eye-in-head trajectory. For instance, in active gaze movements, the end of the pause was better correlated with the gaze end than with either the eye saccade end or the time of eye counterrotation. The hypothesis that cat OPNs participate in controlling gaze shifts is supported by these results, and also by the observation that the movements of both the eyes and the head were transiently interrupted by stimulation of OPNs during gaze shifts. However, we found that the OPN pause could be dissociated from the gaze-motor-error signal producing the gaze shift. First, OPNs resumed discharging when perturbation of head motion briefly interrupted a gaze shift before its intended amplitude was attained. Second, stimulation of caudal SC sites in head-free cat elicited large head-free gaze shifts consistent with the creation of a large gaze-motor-error signal. However, stimulation of the same sites in head-fixed cat produced small "goal-directed" eye saccades, and OPNs paused only for the duration of the latter; neither a pause nor an eye movement occurred when the same stimulation was applied with the eyes at the goal location. We conclude that OPNs can be controlled by neither a simple eye control system nor an absolute gaze control system. Our data cannot be accounted for by existing models describing the control of combined eye-head gaze shifts and therefore put new constraints on future models, which will have to incorporate all the various signals that act synergistically to control gaze shifts.

Extending Newton's Universal Theory of Gravity

NASA Astrophysics Data System (ADS)

Aisenberg, Sol

2011-11-01

This should remove the mystery of Dark Matter. Newton's universal theory of gravity only used the observations of the motion of planets in our solar system. Hubble later used observations of fixed stars in the universe, and showed that the fixed stars were actually galaxies with very large numbers of stars. Newton's universal law of gravity could not explain these new observations without the mystery of dark matter for the additional gravity. In science, when a theory is not able to explain new observations it is necessary to modify the theory or abandon the theory. Rubin observed flat (constant velocity) rotation curves for stars in spiral galaxies. Dark matter was proposed to provide the missing gravity. The equation balancing gravitational force and centripetal force is M*G=v*v*r and for the observed constant velocity v this requires M*G to be a linear function of distance r. If the linear dependence is instead assigned to G instead of M to give a new value for Gn as G+A*r, this will explain the observations in the cosmos and also in our solar system for small r. See ``The Misunderstood Universe'' for more details.

Radial distribution of dust, stars, gas, and star-formation rate in DustPedia⋆ face-on galaxies

NASA Astrophysics Data System (ADS)

Casasola, V.; Cassarà, L. P.; Bianchi, S.; Verstocken, S.; Xilouris, E.; Magrini, L.; Smith, M. W. L.; De Looze, I.; Galametz, M.; Madden, S. C.; Baes, M.; Clark, C.; Davies, J.; De Vis, P.; Evans, R.; Fritz, J.; Galliano, F.; Jones, A. P.; Mosenkov, A. V.; Viaene, S.; Ysard, N.

2017-09-01

Aims: The purpose of this work is the characterization of the radial distribution of dust, stars, gas, and star-formation rate (SFR) in a sub-sample of 18 face-on spiral galaxies extracted from the DustPedia sample. Methods: This study is performed by exploiting the multi-wavelength DustPedia database, from ultraviolet (UV) to sub-millimeter bands, in addition to molecular (12CO) and atomic (Hi) gas maps and metallicity abundance information available in the literature. We fitted the surface-brightness profiles of the tracers of dust and stars, the mass surface-density profiles of dust, stars, molecular gas, and total gas, and the SFR surface-density profiles with an exponential curve and derived their scale-lengths. We also developed a method to solve for the CO-to-H2 conversion factor (αCO) per galaxy by using dust- and gas-mass profiles. Results: Although each galaxy has its own peculiar behavior, we identified a common trend of the exponential scale-lengths versus wavelength. On average, the scale-lengths normalized to the B-band 25 mag/arcsec2 radius decrease from UV to 70 μm, from 0.4 to 0.2, and then increase back up to 0.3 at 500 microns. The main result is that, on average, the dust-mass surface-density scale-length is about 1.8 times the stellar one derived from IRAC data and the 3.6 μm surface brightness, and close to that in the UV. We found a mild dependence of the scale-lengths on the Hubble stage T: the scale-lengths of the Herschel bands and the 3.6 μm scale-length tend to increase from earlier to later types, the scale-length at 70 μm tends to be smaller than that at longer sub-mm wavelength with ratios between longer sub-mm wavelengths and 70 μm that decrease with increasing T. The scale-length ratio of SFR and stars shows a weak increasing trend towards later types. Our αCO determinations are in the range (0.3-9) M⊙ pc-2 (K km s-1)-1, almost invariant by using a fixed dust-to-gas ratio mass (DGR) or a DGR depending on metallicity gradient. DustPedia is a project funded by the EU under the heading "Exploitation of space science and exploration data". It has the primary goal of exploiting existing data in the Herschel Space Observatory and Planck Telescope databases.

Stress-triggered atavistic reprogramming (STAR) addiction: driving force behind head and neck cancer?

PubMed Central

Masuda, Muneyuki; Wakasaki, Takahiro; Toh, Satoshi

2016-01-01

Recent results of the Cancer Genome Atlas on head and neck squamous cell carcinoma (HNSCC) revealed that HNSCC lacked predominant gain-of-function mutations in oncogenes, whereas an essential role for epigenetics in oncogenesis has become apparent. In parallel, it has gained general acceptance that cancer is considered as complex adaptive system, which evolves responding environmental selective pressures. This somatic evolution appears to proceed concurrently with the acquisition of an atavistic pluripotent state (i.e., “stemness”), which is inducible by intrinsic epigenetic reprogramming program as demonstrated by induced pluripotent stem (iPS) cells. This Nobel prize-winning discovery has markedly accelerated and expanded cancer stem cell research from the point of epigenetic reprogramming. Taken together, we hypothesize that stress-triggered atavistic reprogramming (STAR) may be the major driving force of HNSCC evolution. In this perspective, we discuss the possible mechanisms of STAR in HNSCC, focusing on recent topics of epigenetic reprogramming in developmental and cancer cell biology. PMID:27429838

The horizontal and vertical cervico-ocular reflexes of the rabbit.

PubMed

Barmack, N H; Nastos, M A; Pettorossi, V E

1981-11-16

Horizontal and vertical cervico-ocular reflexes of the rabbit (HCOR, VCOR) were evoked by sinusoidal oscillation of the body about the vertical and longitudinal axes while the head was fixed. These reflexes were studied over a frequency range of 0.005-0.800 Hz and at stimulus amplitudes of +/- 10 degrees. When the body of the rabbit was rotated horizontally clockwise around the fixed head, clockwise conjugate eye movements were evoked. When the body was rotated about the longitudinal axis onto the right side, the right eye rotated down and the left eye rotated up. The mean gain of the HCOR (eye velocity/body velocity) rose from 0.21 and 0.005 Hz to 0.27 at 0.020 Hz and then declined to 0.06 at 0.3Hz. The gain of the VCOR was less than the gain of the HCOR by a factor of 2-3. The HCOR was measured separately and in combination with the horizontal vestibulo-ocular reflex (HVOR). These reflexes combine linearly. The relative movements of the first 3 cervical vertebrae during stimulation of the HCOR and VCOR were measured. For the HCOR, the largest angular displacement (74%) occurs between C1 and C2. For the VCOR, the largest relative angular displacement (45%) occurs between C2 and C3. Step horizontal clockwise rotation of the head and body (HVOR) evoked low velocity counterclockwise eye movements followed by fast clockwise (resetting) eye movements. Step horizontal clockwise rotation of the body about the fixed head (HCOR) evoked low velocity clockwise eye movements which were followed by fast clockwise eye movements. Step horizontal clockwise rotation of the head about the fixed body (HCOR + HVOR) evoked low velocity counterclockwise eye movements which were not interrupted by fast clockwise eye movements. These data provide further evidence for a linear combination of independent HCOR and HVOR signals.

Roles of gravitational cues and efference copy signals in the rotational updating of memory saccades.

PubMed

Klier, Eliana M; Angelaki, Dora E; Hess, Bernhard J M

2005-07-01

Primates are able to localize a briefly flashed target despite intervening movements of the eyes, head, or body. This ability, often referred to as updating, requires extraretinal signals related to the intervening movement. With active roll rotations of the head from an upright position it has been shown that the updating mechanism is 3-dimensional, robust, and geometrically sophisticated. Here we examine whether such a rotational updating mechanism operates during passive motion both with and without inertial cues about head/body position in space. Subjects were rotated from either an upright or supine position, about a nasal-occipital axis, briefly shown a world-fixed target, rotated back to their original position, and then asked to saccade to the remembered target location. Using this paradigm, we tested subjects' abilities to update from various tilt angles (0, +/-30, +/-45, +/-90 degrees), to 8 target directions and 2 target eccentricities. In the upright condition, subjects accurately updated the remembered locations from all tilt angles independent of target direction or eccentricity. Slopes of directional errors versus tilt angle ranged from -0.011 to 0.15, and were significantly different from a slope of 1 (no compensation for head-in-space roll) and a slope of 0.9 (no compensation for eye-in-space roll). Because the eyes, head, and body were fixed throughout these passive movements, subjects could not use efference copies or neck proprioceptive cues to assess the amount of tilt, suggesting that vestibular signals and/or body proprioceptive cues suffice for updating. In the supine condition, where gravitational signals could not contribute, slopes ranged from 0.60 to 0.82, indicating poor updating performance. Thus information specifying the body's orientation relative to gravity is critical for maintaining spatial constancy and for distinguishing body-fixed versus world-fixed reference frames.

Effect of viewing distance on the generation of vertical eye movements during locomotion

NASA Technical Reports Server (NTRS)

Moore, S. T.; Hirasaki, E.; Cohen, B.; Raphan, T.

1999-01-01

Vertical head and eye coordination was studied as a function of viewing distance during locomotion. Vertical head translation and pitch movements were measured using a video motion analysis system (Optotrak 3020). Vertical eye movements were recorded using a video-based pupil tracker (Iscan). Subjects (five) walked on a linear treadmill at a speed of 1.67 m/s (6 km/h) while viewing a target screen placed at distances ranging from 0.25 to 2.0 m at 0. 25-m intervals. The predominant frequency of vertical head movement was 2 Hz. In accordance with previous studies, there was a small head pitch rotation, which was compensatory for vertical head translation. The magnitude of the vertical head movements and the phase relationship between head translation and pitch were little affected by viewing distance, and tended to orient the naso-occipital axis of the head at a point approximately 1 m in front of the subject (the head fixation distance or HFD). In contrast, eye velocity was significantly affected by viewing distance. When viewing a far (2-m) target, vertical eye velocity was 180 degrees out of phase with head pitch velocity, with a gain of 0. 8. This indicated that the angular vestibulo-ocular reflex (aVOR) was generating the eye movement response. The major finding was that, at a close viewing distance (0.25 m), eye velocity was in phase with head pitch and compensatory for vertical head translation, suggesting that activation of the linear vestibulo-ocular reflex (lVOR) was contributing to the eye movement response. There was also a threefold increase in the magnitude of eye velocity when viewing near targets, which was consistent with the goal of maintaining gaze on target. The required vertical lVOR sensitivity to cancel an unmodified aVOR response and generate the observed eye velocity magnitude for near targets was almost 3 times that previously measured. Supplementary experiments were performed utilizing body-fixed active head pitch rotations at 1 and 2 Hz while viewing a head-fixed target. Results indicated that the interaction of smooth pursuit and the aVOR during visual suppression could modify both the gain and phase characteristics of the aVOR at frequencies encountered during locomotion. When walking, targets located closer than the HFD (1.0 m) would appear to move in the same direction as the head pitch, resulting in suppression of the aVOR. The results of the head-fixed target experiment suggest that phase modification of the aVOR during visual suppression could play a role in generating eye movements consistent with the goal of maintaining gaze on targets closer than the HFD, which would augment the lVOR response.

STAR--people-powered prioritization: a 21st-century solution to allocation headaches.

PubMed

Airoldi, Mara; Morton, Alec; Smith, Jenifer A E; Bevan, Gwyn

2014-11-01

The aim of cost effectiveness analysis (CEA) is to inform the allocation of scarce resources. CEA is routinely used in assessing the cost-effectiveness of specific health technologies by agencies such as the National Institute for Health and Clinical Excellence (NICE) in England and Wales. But there is extensive evidence that because of barriers of accessibility and acceptability, CEA has not been used by local health planners in their annual task of allocating fixed budgets to a wide range of types of health care. This paper argues that these planners can use Socio Technical Allocation of Resources (STAR) for that task. STAR builds on the principles of CEA and the practice of program budgeting and marginal analysis. STAR uses requisite models to assess the cost-effectiveness of all interventions considered for resource reallocation by explicitly applying the theory of health economics to evidence of scale, costs, and benefits, with deliberation facilitated through an interactive social process of engaging key stakeholders. In that social process, the stakeholders generate missing estimates of scale, costs, and benefits of the interventions; develop visual models of their relative cost-effectiveness; and interpret the results. We demonstrate the feasibility of STAR by showing how it was used by a local health planning agency of the English National Health Service, the Isle of Wight Primary Care Trust, to allocate a fixed budget in 2008 and 2009. © The Author(s) 2014.

Astronomische Konzepte und Jenseitsvorstellungen in den Pyramidentexten.

NASA Astrophysics Data System (ADS)

Krauss, R.

The Egyptian pyramid texts were first written down around 2300 B.C. They are based on the religious belief in a stellar hereafter and contain the astronomical knowledge of their authors. For example, the ecliptical belt was understood as a canal, on which moon and planets cruise; of the latter Mercury, Venus and Mars were identified. On the basis of their visibility in the course of a year the fixed stars were divided into two groups; a southern group with a period of invisibility and a northern group with continual visibility. The ecliptical "canal" was correctly identified as a division line between the two groups of fixed stars. The aim of this book is to bring these texts foreward to a better understanding of their astronomical background.

X-Raying the Beating Heart of a Newborn Star: Rotational Modulation of High-Energy Radiation from V1647 Ori

NASA Technical Reports Server (NTRS)

Hamaguchi, Kenji; Grosso, Nicolas; Kastner, Joel H.; Weintraub, David A.; Richmond, Michael; Petre, Robert; Teets, William K.; Principe, David

2012-01-01

We report a periodicity of approx.1 day in the highly elevated X-ray emission from the protostar V1647 Ori during its two recent multiple-year outbursts of mass accretion. This periodicity is indicative of protostellar rotation at near-breakup speed. Modeling of the phased X-ray light curve indicates the high-temperature ( 50 MK), X-ray-emitting plasma, which is most likely heated by accretion-induced magnetic reconnection, resides in dense ( 5 1010 cm.3), pancake-shaped magnetic footprints where the accretion stream feeds the newborn star. The sustained X-ray periodicity of V1647 Ori demonstrates that such protostellar magnetospheric accretion configurations can be stable over timescales of years. Subject headings: stars: formation stars: individual (V1647 Ori) stars: pre-main sequence X-rays: stars

Evaluation of the use of automatic exposure control and automatic tube potential selection in low-dose cerebrospinal fluid shunt head CT.

PubMed

Wallace, Adam N; Vyhmeister, Ross; Bagade, Swapnil; Chatterjee, Arindam; Hicks, Brandon; Ramirez-Giraldo, Juan Carlos; McKinstry, Robert C

2015-06-01

Cerebrospinal fluid shunts are primarily used for the treatment of hydrocephalus. Shunt complications may necessitate multiple non-contrast head CT scans resulting in potentially high levels of radiation dose starting at an early age. A new head CT protocol using automatic exposure control and automated tube potential selection has been implemented at our institution to reduce radiation exposure. The purpose of this study was to evaluate the reduction in radiation dose achieved by this protocol compared with a protocol with fixed parameters. A retrospective sample of 60 non-contrast head CT scans assessing for cerebrospinal fluid shunt malfunction was identified, 30 of which were performed with each protocol. The radiation doses of the two protocols were compared using the volume CT dose index and dose length product. The diagnostic acceptability and quality of each scan were evaluated by three independent readers. The new protocol lowered the average volume CT dose index from 15.2 to 9.2 mGy representing a 39 % reduction (P < 0.01; 95 % CI 35-44 %) and lowered the dose length product from 259.5 to 151.2 mGy/cm representing a 42 % reduction (P < 0.01; 95 % CI 34-50 %). The new protocol produced diagnostically acceptable scans with comparable image quality to the fixed parameter protocol. A pediatric shunt non-contrast head CT protocol using automatic exposure control and automated tube potential selection reduced patient radiation dose compared with a fixed parameter protocol while producing diagnostic images of comparable quality.

A Program Evaluation Comparison of a Head Start and Public School Kindergarten Reading Curriculum

ERIC Educational Resources Information Center

Jennings, Tanesha

2014-01-01

In order for students to be successful in school, strong foundations are needed at the earliest grades. In a district in central Mississippi, many students entering public school from Head Start were not able to identify alphabet letters or produce letter sounds, based on results of the 2011 Standardized Test for the Assessment of Reading (STAR).…

Evaluation of stereoscopic video cameras synchronized with the movement of an operator's head on the teleoperation of the actual backhoe shovel

NASA Astrophysics Data System (ADS)

Minamoto, Masahiko; Matsunaga, Katsuya

1999-05-01

Operator performance while using a remote controlled backhoe shovel is described for three different stereoscopic viewing conditions: direct view, fixed stereoscopic cameras connected to a helmet mounted display (HMD), and rotating stereo camera connected and slaved to the head orientation of a free moving stereo HMD. Results showed that the head- slaved system provided the best performance.

Three-dimensional vestibular eye and head reflexes of the chameleon: characteristics of gain and phase and effects of eye position on orientation of ocular rotation axes during stimulation in yaw direction.

PubMed

Haker, H; Misslisch, H; Ott, M; Frens, M A; Henn, V; Hess, K; Sándor, P S

2003-07-01

We investigated gaze-stabilizing reflexes in the chameleon using the three-dimensional search-coil technique. Animals were rotated sinusoidally around an earth-vertical axis under head-fixed and head-free conditions, in the dark and in the light. Gain, phase and the influence of eye position on vestibulo-ocular reflex rotation axes were studied. During head-restrained stimulation in the dark, vestibulo-ocular reflex gaze gains were low (0.1-0.3) and phase lead decreased with increasing frequencies (from 100 degrees at 0.04 Hz to < 30 degrees at 1 Hz). Gaze gains were larger during stimulation in the light (0.1-0.8) with a smaller phase lead (< 30 degrees) and were close to unity during the head-free conditions (around 0.6 in the dark, around 0.8 in the light) with small phase leads. These results confirm earlier findings that chameleons have a low vestibulo-ocular reflex gain during head-fixed conditions and stimulation in the dark and higher gains during head-free stimulation in the light. Vestibulo-ocular reflex eye rotation axes were roughly aligned with the head's rotation axis and did not systematically tilt when the animals were looking eccentrically, up- or downward (as predicted by Listing's Law). Therefore, vestibulo-ocular reflex responses in the chameleon follow a strategy, which optimally stabilizes the entire retinal images, a result previously found in non-human primates.

Autonomous star tracker based on active pixel sensors (APS)

NASA Astrophysics Data System (ADS)

Schmidt, U.

2017-11-01

Star trackers are opto-electronic sensors used onboard of satellites for the autonomous inertial attitude determination. During the last years, star trackers became more and more important in the field of the attitude and orbit control system (AOCS) sensors. High performance star trackers are based up today on charge coupled device (CCD) optical camera heads. The Jena-Optronik GmbH is active in the field of opto-electronic sensors like star trackers since the early 80-ties. Today, with the product family ASTRO5, ASTRO10 and ASTRO15, all marked segments like earth observation, scientific applications and geo-telecom are supplied to European and Overseas customers. A new generation of star trackers can be designed based on the APS detector technical features. The measurement performance of the current CCD based star trackers can be maintained, the star tracker functionality, reliability and robustness can be increased while the unit costs are saved.

Wave-Ice Interaction and the Marginal Ice Zone

DTIC Science & Technology

2013-09-30

concept, using a high-quality attitude and heading reference system ( AHRS ) together with an accurate twin-antennae GPS compass. The instruments logged...the AHRS parameters at 50Hz, together with GPS-derived fixes, heading (accurate to better than 1o) and velocities at 10Hz. The 30MB hourly files

Push Type Fastener

NASA Technical Reports Server (NTRS)

Jackson, Steven A. (Inventor)

1996-01-01

A push type fastener for fastening a movable structural part to a fixed structural part, wherein the coupling and decoupling actions are both a push type operation, the fastener consisting of a plunger having a shank with a plunger head at one end and a threaded end portion at the other end, an expandable grommet adapted to receive the plunger shank there through, and an attachable head which is securable to the threaded end of the plunger shank. The fastener requires each structural part to be provided with an aperture and the attachable head to be smaller than the aperture in the second structural part. The plunger is extensible through the grommet and is structurally configured with an external camming surface which is cooperatively engageable with internal surfaces of the grommet so that when the plunger is inserted in the grommet, the relative positioning of said cooperable camming surfaces determines the expansion of the grommet. Coupling of the parts is effected when the grommet is inserted in the aperture in the fixed structural part and expanded by pushing the plunger head and plunger at least a minimal distance through the grommet. Decoupling is effected by pushing the attachable head.

Press-fit bipolar radial head arthroplasty, midterm results.

PubMed

Kodde, Izaäk F; Heijink, Andras; Kaas, Laurens; Mulder, Paul G H; van Dijk, C Niek; Eygendaal, Denise

2016-08-01

Theoretical advantages of bipolar compared with monopolar radial head arthroplasty include better accommodation of radiocapitellar malalignment, reduction of capitellar abrasion, and reduction of stress at the bone-implant interfaces. Our purpose was to report the midterm results of press-fit bipolar radial head arthroplasty. Thirty patients were treated by press-fit bipolar radial head arthroplasty for acute fracture of the radial head, failed earlier treatment, or post-traumatic sequelae. Three patients were lost to follow-up. Results are presented for the remaining 27 patients. At mean follow-up of 48 months (range, 28-73), there had been 3 (11%) revisions. Two involved conversion to prosthetic radiocapitellar hemiarthroplasty for symptomatic capitellar abrasion; a third involved exchange of the articular component (ie, head) for instability. In all, the stems appeared well fixed. A prosthesis in a subluxed position accounted for the 1 (4%) additional radiologic failure. The average flexion-extension arc was 136° (range, 120°-145°), and the average pronation-supination arc was 138° (range, 70°-180°). According to the Mayo Elbow Performance Score, the combined excellent and good results accounted for 70%. The overall midterm outcome of this series of 30 press-fit bipolar radial head arthroplasties can be considered favorable. Although the revision rate was 11%, the stems were well fixed in all. There was 1 (4%) additional radiologic failure. We suggest considering a press-fit bipolar radial head prosthesis for acute comminuted radial head fractures with limited bone loss of the proximal radius. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Variable Star Catalogs: Their Past, Present and Future

NASA Astrophysics Data System (ADS)

Samus, N. N.; Kazarovets, E. V.; Kireeva, N. N.; Pastukhova, E. N.; Durlevich, O. V.

2010-02-01

After the second World War, the International Astronomical Union made astronomers of the Soviet Union responsible for variable-star catalogues. This work has been continued ever since the first edition of the General Catalogue of Variable Stars compiled by the team headed by P. P. Parenago and B. V. Kukarkin and published in 1948. Currently, the catalogue work is a joint project of the Institute of Astronomy (Russian Academy of Sciences) and Sternberg Astronomical Institute (Moscow University). This paper is a brief review of recent trends in the field of variable-star catalogues. We discuss problems as well as new prospects related to modern large-scale automatic photometric sky surveys, and outline the state of discussions on the future of the variable-star catalogues in the profile commissions of the IAU.

Ultra-Stable Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (5STAR)

NASA Technical Reports Server (NTRS)

Dunagan, Stephen E.; Johnson, Roy R.; Redemann, Jens; Holben, Brent N.; Schmidt, Beat; Flynn, Connor Joseph; Fahey, Lauren; LeBlanc, Samuel; Liss, Jordan; Kacenelenbogen, Meloe S.;

The Analysis of Electrical Energy Consumption of the Impact Screwdriver During Assembly of Fixed Threaded Joints

NASA Astrophysics Data System (ADS)

Grinevich, I.; Nikishin, Vl.; Mozga, N.; Laitans, M.

2017-06-01

The paper deals with the possibilities of reducing the consumption of electrical energy of the impact screwdriver during the assembly of fixed threaded joints. The recommendations related to a decrease in electrical energy consumption would allow reducing product costs but so far there have been no such recommendations from the producers of the tool as to the effective operating regimes of the impact screwdrivers in relation to electrical energy consumption and necessary tightening moment of the nut. The aim of the study is to find out the economical operating mode of the electrical impact screwdriver when assembling fixed threaded joints. By varying the set speed of the rotor head and working time of the impact mechanism, there is an opportunity to determine electrical energy consumption of the tool for the given tightening moment. The results of the experiment show that at the same tightening moment obtained the electrical energy consumption of the impact screwdriver is less at a higher starting set speed of the rotor head but shorter operating time of the impact mechanism than at a lower speed of the rotor head and longer operating time of the impact mechanism.

Hippocampus-Dependent Goal Localization by Head-Fixed Mice in Virtual Reality.

PubMed

Sato, Masaaki; Kawano, Masako; Mizuta, Kotaro; Islam, Tanvir; Lee, Min Goo; Hayashi, Yasunori

2017-01-01

The demonstration of the ability of rodents to navigate in virtual reality (VR) has made it an important behavioral paradigm for studying spatially modulated neuronal activity in these animals. However, their behavior in such simulated environments remains poorly understood. Here, we show that encoding and retrieval of goal location memory in mice head-fixed in VR depends on the postsynaptic scaffolding protein Shank2 and the dorsal hippocampus. In our newly developed virtual cued goal location task, a head-fixed mouse moves from one end of a virtual linear track to seek rewards given at a target location along the track. The mouse needs to visually recognize the target location and stay there for a short period of time to receive the reward. Transient pharmacological blockade of fast glutamatergic synaptic transmission in the dorsal hippocampus dramatically and reversibly impaired performance of this task. Encoding and updating of virtual cued goal location memory was impaired in mice deficient in the postsynaptic scaffolding protein Shank2, a mouse model of autism that exhibits impaired spatial learning in a real environment. These results highlight the crucial roles of the dorsal hippocampus and postsynaptic protein complexes in spatial learning and navigation in VR.

Hippocampus-Dependent Goal Localization by Head-Fixed Mice in Virtual Reality

PubMed Central

Kawano, Masako; Mizuta, Kotaro; Islam, Tanvir; Lee, Min Goo; Hayashi, Yasunori

2017-01-01

Abstract The demonstration of the ability of rodents to navigate in virtual reality (VR) has made it an important behavioral paradigm for studying spatially modulated neuronal activity in these animals. However, their behavior in such simulated environments remains poorly understood. Here, we show that encoding and retrieval of goal location memory in mice head-fixed in VR depends on the postsynaptic scaffolding protein Shank2 and the dorsal hippocampus. In our newly developed virtual cued goal location task, a head-fixed mouse moves from one end of a virtual linear track to seek rewards given at a target location along the track. The mouse needs to visually recognize the target location and stay there for a short period of time to receive the reward. Transient pharmacological blockade of fast glutamatergic synaptic transmission in the dorsal hippocampus dramatically and reversibly impaired performance of this task. Encoding and updating of virtual cued goal location memory was impaired in mice deficient in the postsynaptic scaffolding protein Shank2, a mouse model of autism that exhibits impaired spatial learning in a real environment. These results highlight the crucial roles of the dorsal hippocampus and postsynaptic protein complexes in spatial learning and navigation in VR. PMID:28484738

Theoretical uncertainties on the radius of low- and very-low-mass stars

NASA Astrophysics Data System (ADS)

Tognelli, E.; Prada Moroni, P. G.; Degl'Innocenti, S.

2018-05-01

We performed an analysis of the main theoretical uncertainties that affect the radius of low- and very-low-mass stars predicted by current stellar models. We focused on stars in the mass range 0.1-1 M⊙, on both the zero-age main sequence (ZAMS) and on 1, 2, and 5 Gyr isochrones. First, we quantified the impact on the radius of the uncertainty of several quantities, namely the equation of state, radiative opacity, atmospheric models, convection efficiency, and initial chemical composition. Then, we computed the cumulative radius error stripe obtained by adding the radius variation due to all the analysed quantities. As a general trend, the radius uncertainty increases with the stellar mass. For ZAMS structures the cumulative error stripe of very-low-mass stars is about ±2 and ±3 per cent, while at larger masses it increases up to ±4 and ±5 per cent. The radius uncertainty gets larger and age dependent if isochrones are considered, reaching for M ˜ 1 M⊙ about +12(-15) per cent at an age of 5 Gyr. We also investigated the radius uncertainty at a fixed luminosity. In this case, the cumulative error stripe is the same for both ZAMS and isochrone models and it ranges from about ±4 to +7 and +9(-5) per cent. We also showed that the sole uncertainty on the chemical composition plays an important role in determining the radius error stripe, producing a radius variation that ranges between about ±1 and ±2 per cent on ZAMS models with fixed mass and about ±3 and ±5 per cent at a fixed luminosity.

Galileo Attitude Determination: Experiences with a Rotating Star Scanner

NASA Technical Reports Server (NTRS)

Merken, L.; Singh, G.

1991-01-01

The Galileo experience with a rotating star scanner is discussed in terms of problems encountered in flight, solutions implemented, and lessons learned. An overview of the Galileo project and the attitude and articulation control subsystem is given and the star scanner hardware and relevant software algorithms are detailed. The star scanner is the sole source of inertial attitude reference for this spacecraft. Problem symptoms observed in flight are discussed in terms of effects on spacecraft performance and safety. Sources of thse problems include contributions from flight software idiosyncrasies and inadequate validation of the ground procedures used to identify target stars for use by the autonomous on-board star identification algorithm. Problem fixes (some already implemented and some only proposed) are discussed. A general conclusion is drawn regarding the inherent difficulty of performing simulation tests to validate algorithms which are highly sensitive to external inputs of statistically 'rare' events.

Spectral probes of the holographic Fermi ground state: Dialing between the electron star and AdS Dirac hair

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

Cubrovic, Mihailo; Liu Yan; Schalm, Koenraad

2011-10-15

We argue that the electron star and the anti-de Sitter (AdS) Dirac hair solution are two limits of the free charged Fermi gas in AdS. Spectral functions of holographic duals to probe fermions in the background of electron stars have a free parameter that quantifies the number of constituent fermions that make up the charge and energy density characterizing the electron star solution. The strict electron star limit takes this number to be infinite. The Dirac hair solution is the limit where this number is unity. This is evident in the behavior of the distribution of holographically dual Fermi surfaces.more » As we decrease the number of constituents in a fixed electron star background the number of Fermi surfaces also decreases. An improved holographic Fermi ground state should be a configuration that shares the qualitative properties of both limits.« less

Effects of head tilt on visual field testing with a head-mounted perimeter imo

PubMed Central

Matsumoto, Chota; Nomoto, Hiroki; Numata, Takuya; Eura, Mariko; Yamashita, Marika; Hashimoto, Shigeki; Okuyama, Sachiko; Kimura, Shinji; Yamanaka, Kenzo; Chiba, Yasutaka; Aihara, Makoto; Shimomura, Yoshikazu

2017-01-01

Purpose A newly developed head-mounted perimeter termed “imo” enables visual field (VF) testing without a fixed head position. Because the positional relationship between the subject’s head and the imo is fixed, the effects of head position changes on the test results are small compared with those obtained using a stationary perimeter. However, only ocular counter-roll (OCR) induced by head tilt might affect VF testing. To quantitatively reveal the effects of head tilt and OCR on the VF test results, we investigated the associations among the head-tilt angle, OCR amplitude and VF testing results. Subjects and methods For 20 healthy subjects, we binocularly recorded static OCR (s-OCR) while tilting the subject’s head at an arbitrary angle ranging from 0° to 60° rightward or leftward in 10° increments. By monitoring iris patterns, we evaluated the s-OCR amplitude. We also performed blind spot detection while tilting the subject’s head by an arbitrary angle ranging from 0° to 50° rightward or leftward in 10° increments to calculate the angle by which the blind spot rotates because of head tilt. Results The association between s-OCR amplitude and head-tilt angle showed a sinusoidal relationship. In blind spot detection, the blind spot rotated to the opposite direction of the head tilt, and the association between the rotation angle of the blind spot and the head-tilt angle also showed a sinusoidal relationship. The rotation angle of the blind spot was strongly correlated with the s-OCR amplitude (R2≥0.94, p<0.0001). A head tilt greater than 20° with imo causes interference between adjacent test areas. Conclusions Both the s-OCR amplitude and the rotation angle of the blind spot were correlated with the head-tilt angle by sinusoidal regression. The rotated VF was correlated with the s-OCR amplitude. During perimetry using imo, the change in the subject’s head tilt should be limited to 20°. PMID:28945777

Transformation of a Virgo Cluster dwarf irregular galaxy by ram pressure stripping: IC3418 and its fireballs

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

Kenney, Jeffrey D. P.; Geha, Marla; Jáchym, Pavel

We present optical imaging and spectroscopy and H I imaging of the Virgo Cluster galaxy IC 3418, which is likely a 'smoking gun' example of the transformation of a dwarf irregular into a dwarf elliptical galaxy by ram pressure stripping. IC 3418 has a spectacular 17 kpc length UV-bright tail comprised of knots, head-tail, and linear stellar features. The only Hα emission arises from a few H II regions in the tail, the brightest of which are at the heads of head-tail UV sources whose tails point toward the galaxy ('fireballs'). Several of the elongated tail sources have Hα peaksmore » outwardly offset by ∼80-150 pc from the UV peaks, suggesting that gas clumps continue to accelerate through ram pressure, leaving behind streams of newly formed stars which have decoupled from the gas. Absorption line strengths, measured from Keck DEIMOS spectra, together with UV colors, show star formation stopped 300 ± 100 Myr ago in the main body, and a strong starburst occurred prior to quenching. While neither Hα nor H I emission are detected in the main body of the galaxy, we have detected 4 × 10{sup 7} M {sub ☉} of H I from the tail with the Very Large Array. The velocities of tail H II regions, measured from Keck LRIS spectra, extend only a small fraction of the way to the cluster velocity, suggesting that star formation does not happen in more distant parts of the tail. Stars in the outer tail have velocities exceeding the escape speed, but some in the inner tail should fall back into the galaxy, forming halo streams.« less

The Multi-site All-Sky CAmeRA (MASCARA). Finding transiting exoplanets around bright (mV < 8) stars

NASA Astrophysics Data System (ADS)

Talens, G. J. J.; Spronck, J. F. P.; Lesage, A.-L.; Otten, G. P. P. L.; Stuik, R.; Pollacco, D.; Snellen, I. A. G.

2017-05-01

This paper describes the design, operations, and performance of the Multi-site All-Sky CAmeRA (MASCARA). Its primary goal is to find new exoplanets transiting bright stars, 4 < mV < 8, by monitoring the full sky. MASCARA consists of one northern station on La Palma, Canary Islands (fully operational since February 2015), one southern station at La Silla Observatory, Chile (operational from early 2017), and a data centre at Leiden Observatory in the Netherlands. Both MASCARA stations are equipped with five interline CCD cameras using wide field lenses (24 mm focal length) with fixed pointings, which together provide coverage down to airmass 3 of the local sky. The interline CCD cameras allow for back-to-back exposures, taken at fixed sidereal times with exposure times of 6.4 sidereal seconds. The exposures are short enough that the motion of stars across the CCD does not exceed one pixel during an integration. Astrometry and photometry are performed on-site, after which the resulting light curves are transferred to Leiden for further analysis. The final MASCARA archive will contain light curves for 70 000 stars down to mV = 8.4, with a precision of 1.5% per 5 minutes at mV = 8.

Star formation history and chemical enrichment in the early Universe: clues from the rest-optical and rest-UV spectra of z~2-3 star-forming galaxies in the Keck Baryonic Structure Survey

NASA Astrophysics Data System (ADS)

Strom, Allison L.

2017-01-01

Galaxies at the peak of cosmic star formation (z~2-3) exhibit significantly higher star formation rates and gas fractions at fixed stellar mass than nearby galaxies. These z~2-3 galaxies are also distinct in terms of their nebular spectra, reflecting important differences not only in the physical conditions of their interstellar medium (e.g., electron density and gas-phase metallicity), but also in the details of their massive stellar populations, especially their ionizing radiation fields. Jointly observing galaxies' HII regions, at rest-UV and rest-optical wavelengths, and massive stars, at rest-UV wavelengths, is central to constructing a framework for understanding the differences between z~2-3 and z~0 star-forming galaxies and for self-consistently explaining the trends observed in the high-redshift population. My thesis is based on data from the Keck Baryonic Structure Survey (KBSS), which uniquely combines observations of individual galaxies in these two bandpasses. In total, the near-infrared component of the KBSS includes spectra of >700 z~2-3 galaxies obtained with Keck/MOSFIRE. I will present these results along with a detailed analysis of the full rest-optical (3600-7000 Ang) nebular spectra of ~400 galaxies, showing that high-redshift galaxies exhibit uniformly high degrees of ionization and excitation with respect to most z~0 galaxies. Combined with observations of the same galaxies' rest-UV spectra (obtained with Keck/LRIS) and photoionization model predictions, these results suggest that the disparity arises from differences in the shape of the ionizing radiation field at fixed gas-phase oxygen abundance, most likely due to the effects of Fe-poor massive binary stars. My comprehensive spectroscopic study of an unprecedentedly large sample of z~2-3 galaxies offers compelling evidence that the distinct chemical abundance patterns observed in these galaxies are the result of systematic differences in their star formation histories.

Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) Instrument Improvements

NASA Technical Reports Server (NTRS)

Dunagan, Stephen E.; Redemann, Jens; Chang, Cecilia; Dahlgren, Robert; Fahey, Lauren; Flynn, Connor; Johnson, Roy; Kacenelenbogen, Meloe; Leblanc, Samuel; Liss, Jordan;

What Makes the Foucault Pendulum Move among the Stars?

NASA Astrophysics Data System (ADS)

Phillips, Norman

2004-11-01

Foucault's pendulum exhibition in 1851 occurred in an era now known by development of the theorems of Coriolis and the formulation of dynamical meteorology by Ferrel. Yet today the behavior of the pendulum is often misunderstood. The existence of a horizontal component of Newtonian gravitation is essential for understanding the behavior with respect to the stars. Two simple mechanical principles describe why the path of oscillation is fixed only at the poles; the principle of centripetal acceleration and the principle of conservation of angular momentum. A sky map is used to describe the elegant path among the stars produced by these principles.

Predictions from star formation in the multiverse

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

Bousso, Raphael; Leichenauer, Stefan

2010-03-15

We compute trivariate probability distributions in the landscape, scanning simultaneously over the cosmological constant, the primordial density contrast, and spatial curvature. We consider two different measures for regulating the divergences of eternal inflation, and three different models for observers. In one model, observers are assumed to arise in proportion to the entropy produced by stars; in the others, they arise at a fixed time (5 or 10x10{sup 9} years) after star formation. The star formation rate, which underlies all our observer models, depends sensitively on the three scanning parameters. We employ a recently developed model of star formation in themore » multiverse, a considerable refinement over previous treatments of the astrophysical and cosmological properties of different pocket universes. For each combination of observer model and measure, we display all single and bivariate probability distributions, both with the remaining parameter(s) held fixed and marginalized. Our results depend only weakly on the observer model but more strongly on the measure. Using the causal diamond measure, the observed parameter values (or bounds) lie within the central 2{sigma} of nearly all probability distributions we compute, and always within 3{sigma}. This success is encouraging and rather nontrivial, considering the large size and dimension of the parameter space. The causal patch measure gives similar results as long as curvature is negligible. If curvature dominates, the causal patch leads to a novel runaway: it prefers a negative value of the cosmological constant, with the smallest magnitude available in the landscape.« less

Method and Apparatus for Assessment of Changes in Intracranial Pressure

NASA Technical Reports Server (NTRS)

Yost, William T. (Inventor); Cantrell, John H. (Inventor)

2002-01-01

A non-invasive method and apparatus for monitoring changes in intracranial pressure which removes extracranial effects from the measurements. The method and apparatus can include the supplying of a fixed frequency electrical output to a transducer coupled to the patient's head, thereby generating an acoustical tone burst in the patient's head which generates a first echo and a second echo, the first echo reflecting from a first interface in the side of the patient's head coupled to the transducer, and the second echo reflecting from a second interface at the opposite side of the patient's head. The first and second echoes are received by the transducer which can generate a first electrical signal and a second electrical signal, wherein the first and second electrical signals vary in accordance with the corresponding first and second echoes. The counterbalancing phase shifts required to bring about quadrature between each of the first and second electrical signals and the fixed frequency electrical output can be measured, and values for the change in intracranial distance based on the changes in the counterbalancing phase shifts can be obtained.

Ghost Head Nebula

NASA Technical Reports Server (NTRS)

1999-01-01

Looking like a colorful holiday card, a new image from NASA's Hubble Space Telescope reveals a vibrant green and red nebula far from Earth.

The image of NGC 2080, taken by Hubble's Wide Field and Planetary Camera 2, designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif., is available online at http://www.jpl.nasa.gov/images/wfpc . Images like this help astronomers investigate star formation in nebulas.

NGC 2080, nicknamed 'The Ghost Head Nebula,' is one of a chain of star-forming regions lying south of the 30 Doradus nebula in the Large Magellanic Cloud. 30 Doradus is the largest star-forming complex in the local group of galaxies. This 'enhanced color' picture is composed of three narrow-band-filter images obtained by Hubble on March 28, 2000.

The red and blue light come from regions of hydrogen gas heated by nearby stars. The green light on the left comes from glowing oxygen. The energy to illuminate the green light is supplied by a powerful stellar wind, a stream of high-speed particles coming from a massive star just outside the image. The central white region is a combination of all three emissions and indicates a core of hot, massive stars in this star-formation region. Intense emission from these stars has carved a bowl-shaped cavity in surrounding gas.

In the white region, the two bright areas (the 'eyes of the ghost') - named A1 (left) and A2 (right) -- are very hot, glowing 'blobs' of hydrogen and oxygen. The bubble in A1 is produced by the hot, intense radiation and powerful stellar wind from one massive star. A2 contains more dust and several hidden, massive stars. The massive stars in A1 and A2 must have formed within the last 10,000 years, since their natal gas shrouds are not yet disrupted by the powerful radiation of the newborn stars.

The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract with the Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international co-operation between the European Space Agency and NASA. The California Institute of Technology in Pasadena manages JPL for NASA.

Strength of fixation constructs for basilar osteotomies of the first metatarsal.

PubMed

Lian, G J; Markolf, K; Cracchiolo, A

1992-01-01

Twenty-four pairs of fresh-frozen human feet had a proximal osteotomy of the first metatarsal that was fixed using either screws, staples, or K wires. Each metatarsal was excised and the specimen was loaded to failure in a cantilever beam configuration by applying a superiorly directed force to the metatarsal head using an MTS servohydraulic test machine. Specimens with a crescentic osteotomy that were fixed using a single screw demonstrated higher mean failure moments than pairs that were fixed with four staples or two K wires; staples were the weakest construct. All specimens fixed with staples failed by bending of the staples without bony fracture; all K wire constructs but one failed by wire bending. Chevron and crescentic osteotomies fixed with a single screw demonstrated equal bending strengths; the bending strength of an oblique osteotomy fixed with two screws was 82% greater than for a crescentic osteotomy fixed with a single screw. Basilar osteotomies of the first metatarsal are useful in correcting metatarsus primus varus often associated with hallux valgus pathology. Fixation strength is an important consideration since weightbearing forces on the head of the first metatarsal acting at a distance from the osteotomy site subject the construct to a dorsiflexion bending moment, as simulated in our tests. Our results show that screw fixation is the strongest method for stabilizing a basilar osteotomy. Based upon the relatively low bending strengths of the staple and K wire constructs, we would not recommend these forms of fixation.(ABSTRACT TRUNCATED AT 250 WORDS)

SU-E-T-130: Are Proton Gantries Needed? An Analysis of 4332 Patient Proton Gantry Treatment Plans From the Past 10 Years

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

Yan, S; Lu, H; Flanz, J

2015-06-15

Purpose: To ascertain the necessity of a proton gantry, as compared to the feasibility of using a horizontal fixed proton beam-line for treatment with advanced technology. Methods: To calculate the percentage of patients that can be treated with a horizontal fixed beam-line instead of a gantry, we analyze the distributions of beam orientations of our proton gantry patients treated over the past 10 years. We identify three horizontal fixed beam geometries (FIXED, BEND and MOVE) with the patient in lying and/or sitting positions. The FIXED geometry includes only table/chair rotations and translations. In BEND, the beam can be bent up/downmore » for up to 20 degrees. MOVE allows for patient head/body angle adjustment. Based on the analysis, we select eight patients whose plan involves beams which are still challenging to achieve with a horizontal fixed beam. These beams are removed in the pencil beam scanning (PBS) plan optimized for the fixed beam-line (PBS-fix). We generate non-coplanar PBS-gantry plans for comparison, and perform a robustness analysis. Results: The percentage of patients with head-and-neck/brain tumors that can be treated with horizontal fixed beam is 44% in FIXED, 70% in 20-degrees BEND, and 100% in 90-degrees MOVE. For torso regions, 99% of the patients can be treated in 20-degree BEND. The target coverage is more homogeneous with PBS-fix plans compared to the clinical scattering treatment plans. The PBS-fix plans reduce the mean dose to organs-at-risk by a factor of 1.1–28.5. PBS-gantry plans are as good as PBS-fix plans, sometimes marginally better. Conclusion: The majority of the beam orientations can be realized with a horizontal fixed beam-line. Challenging non-coplanar beams can be eliminated with PBS delivery. Clinical implementation of the proposed fixed beam-line requires use of robotic patient positioning, further developments in immobilization, and image guidance. However, our results suggest that fixed beam-lines can be as effective as gantries.« less

Star formation, structure, and formation mechanism of cometary globules: near-infrared observations of CG 1 and CG 2

NASA Astrophysics Data System (ADS)

Mäkelä, M. M.; Haikala, L. K.

2013-02-01

Context. Cometary globule (CG) 1 and CG 2 are "classic" cometary globules in the Gum Nebula. They have compact heads and long dusty tails that point away from the centre of the Gum Nebula. Aims: We study the structure of CG 1 and CG 2 and the star formation in them to find clues to the CG formation mechanism. The two possible CG formation mechanisms, radiation-driven implosion (RDI) and a supernova blast wave, produce a characteristic mass distribution where the major part of the mass is situated in either the head (RDI) or the tail (supernova blast). Methods: CG 1 and CG 2 were imaged in the near infrared (NIR) JsHKs bands. NIR photometry was used to locate NIR excess objects and to create visual extinction maps of the CGs. The AV maps allow us to analyse the large-scale structure of CG 1 and CG 2. Archival images from the WISE and Spitzer satellites and HIRES-processed IRAS images were used to study the globule's small-scale structure. Fits were made to the spectral energy distribution plots of the NIR-excess stars to estimate their age and mass. Results: In addition to the previously known CG 1 IRS 1 we discovered three new NIR-excess objects in IR imaging, two in CG 1 and one in CG 2. CG 2 IRS 1 is the first detection of star formation in CG 2. The objects are young low-mass stars. CG 1 IRS 1 is probably a class I protostar in the head of CG 1. CG 1 IRS 1 drives a bipolar outflow, which is very weak in CO, but the cavity walls are seen in reflected light in our NIR and in the Spitzer 3.6 and 4.5 μm images. Strong emission from excited polycyclic aromatic hydrocarbon particles and very small grains were detected in the CG 1 tail. The total mass of CG 1 in the observed area is 41.9 M⊙ of which 16.8 M⊙ lies in the head. For CG 2 these values are 31.0 M⊙ total and 19.1 M⊙ in the head. The observed mass distribution does not offer a firm conclusion for the formation mechanism of the two CGs: CG 1 is in too evolved a state, and in CG 2 part of the globule tail was outside the observed area. Conclusions: Even though the masses of the two CGs are similar, star formation has been more efficient in CG 1. By now, altogether six young low-mass stars have been detected in CG 1 and only one in CG 2. A possible new outflow was discovered to be emanating from CG 1 IRS 1. Based partly on observations done at the European Southern Observatory, La Silla, Chile (ESO programme 078.C-0490).Appendices A and B are available in electronic form at http://www.aanda.orgTables 1-3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr 130.79.128.5 or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/550/A83

2.0 to 2.4 micron spectroscopy of T Tauri stars

NASA Astrophysics Data System (ADS)

Hamann, F.; Simon, M.; Ridgway, S. T.

1988-03-01

Velocity-resolved 2.0-2.5-micron observations of the T Tau stars T, DF, DG, DK, HL, and RY Tau, SU Aur, and GW Ori are presented. For each of these stars except SU Aur, the Brackett gamma line was detected in emission with line widths inthe range of about 130-230 km/s. The Brackett gamma line profile of SU Aur is complex, having components of both emission and absorption. The first measurement of CO band-head emission in DG Tau is reported, and it is shown that published radio continuum fluxes of young stars far exceed what could be produced in an envelope ionized by only the stellar photospheric Lyman continuum. The excess of radio emission is found to be much greater in low-luminosity sources (e.g., the T Tau stars).

Reduction of low frequency error for SED36 and APS based HYDRA star trackers

NASA Astrophysics Data System (ADS)

Ouaknine, Julien; Blarre, Ludovic; Oddos-Marcel, Lionel; Montel, Johan; Julio, Jean-Marc

2017-11-01

In the frame of the CNES Pleiades satellite, a reduction of the star tracker low frequency error, which is the most penalizing error for the satellite attitude control, was performed. For that purpose, the SED36 star tracker was developed, with a design based on the flight qualified SED16/26. In this paper, the SED36 main features will be first presented. Then, the reduction process of the low frequency error will be developed, particularly the optimization of the optical distortion calibration. The result is an attitude low frequency error of 1.1" at 3 sigma along transverse axes. The implementation of these improvements to HYDRA, the new multi-head APS star tracker developed by SODERN, will finally be presented.

Hubble Reveals Stellar Fireworks in ‘Skyrocket’ Galaxy

NASA Image and Video Library

2016-06-29

Fireworks shows are not just confined to Earth’s skies. NASA’s Hubble Space Telescope has captured a spectacular fireworks display in a small, nearby galaxy, which resembles a July 4th skyrocket. A firestorm of star birth is lighting up one end of the diminutive galaxy Kiso 5639. The dwarf galaxy is shaped like a flattened pancake, but because it is tilted edge-on, it resembles a skyrocket, with a brilliant blazing head and a long, star-studded tail. Kiso 5639 is a rare, nearby example of elongated galaxies that occur in abundance at larger distances, where we observe the universe during earlier epochs. Astronomers suggest that the frenzied star birth is sparked by intergalactic gas raining on one end of the galaxy as it drifts through space. “I think Kiso 5639 is a beautiful, up-close example of what must have been common long ago,” said lead researcher Debra Elmegreen of Vassar College, in Poughkeepsie, New York. “The current thinking is that galaxies in the early universe grow from accreting gas from the surrounding neighborhood. It’s a stage that galaxies, including our Milky Way, must go through as they are growing up.” Observations of the early universe, such as Hubble’s Ultra-Deep Field, reveal that about 10 percent of all galaxies have these elongated shapes, and are collectively called “tadpoles.” But studies of the nearby universe have turned up only a few of these unusual galaxies, including Kiso 5639. The development of the nearby star-making tadpole galaxies, however, has lagged behind that of their peers, which have spent billions of years building themselves up into many of the spiral galaxies seen today. Elmegreen used Hubble’s Wide Field Camera 3 to conduct a detailed imaging study of Kiso 5639. The images in different filters reveal information about an object by dissecting its light into its component colors. Hubble’s crisp resolution helped Elmegreen and her team analyze the giant star-forming clumps in Kiso 5639 and determine the masses and ages of the star clusters. The international team of researchers selected Kiso 5639 from a spectroscopic survey of 10 nearby tadpole galaxies, observed with the Grand Canary Telescope in La Palma, Spain, by Jorge Sanchez Almeida and collaborators at the Instituto de Astrofisica de Canarias. The observations revealed that in most of those galaxies, including Kiso 5639, the gas composition is not uniform. The bright gas in the galaxy’s head contains fewer heavier elements (collectively called “metals”), such as carbon and oxygen, than the rest of the galaxy. Stars consist mainly of hydrogen and helium, but cook up other “heavier” elements. When the stars die, they release their heavy elements and enrich the surrounding gas. “The metallicity suggests that there has to be rather pure gas, composed mostly of hydrogen, coming into the star-forming part of the galaxy, because intergalactic space contains more pristine hydrogen-rich gas,” Elmegreen explained. “Otherwise, the starburst region should be as rich in heavy elements as the rest of the galaxy.” Hubble offers a detailed view of the galaxy’s star-making frenzy. The telescope uncovered several dozen clusters of stars in the galaxy’s star-forming head, which spans 2,700 light-years across. These clusters have an average age of less than 1 million years and masses that are three to six times larger than those in the rest of the galaxy. Other star formation is taking place throughout the galaxy but on a much smaller scale. Star clusters in the rest of the galaxy are between several million to a few billion years old. “There is much more star formation going on in the head than what you would expect in such a tiny galaxy,” said team member Bruce Elmegreen of IBM’s Thomas J. Watson’s Research Center, in Yorktown Heights, New York. “And we think the star formation is triggered by the ongoing accretion of metal-poor gas onto a part of an otherwise quiescent dwarf galaxy.” Hubble also revealed giant holes peppered throughout the galaxy’s starburst head. These cavities give the galaxy’s head a Swiss-cheese appearance because numerous supernova detonations – like firework aerial bursts – have carved out holes of rarified superheated gas. The galaxy, located 82 million light-years away, has taken billions of years to develop because it has been drifting through an isolated “desert” in the universe, devoid of much gas. What triggered the starburst in such a backwater galaxy? Based on simulations by Daniel Ceverino of the Center for Astronomy at Heidelberg University in Germany, and other team members, the observations suggest that less than 1 million years ago, Kiso 5639’s leading edge encountered a filament of gas. The filament dropped a large clump of matter onto the galaxy, stoking the vigorous star birth. Debra Elmegreen expects that in the future other parts of the galaxy will join in the star-making fireworks show. “Galaxies rotate, and as Kiso 5639 continues to spin, another part of the galaxy may receive an infusion of new gas from this filament, instigating another round of star birth,” she said. The team’s results have been accepted for publication in The Astrophysical Journal. Other team members include Casiana Munoz-Tunon and Mercedes Filho (Instituto de Astrofísica de Canarias, Canary Islands), Jairo Mendez-Abreu (University of St. Andrews, United Kingdom), John Gallagher (University of Wisconsin-Madison), and Marc Rafelski (NASA's Goddard Space Flight Center, Greenbelt, Maryland). The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

Development and Efficacy Testing of Next Generation Cyanide Antidotes

DTIC Science & Technology

2013-10-01

Preparation of mDMTS A-2.2. HPLC method for DMTS determination in Micelles A-2.3. Head-space solid phase micro-extraction- gas chromatography -mass...Simultaneous determination of cyanide and thiocyanate in plasma by chemical ionization gas chromatography mass-spectrometry (CI-GC-MS). Analytical and...min. Peak integration was performed using Star Chromatography Workstation Version 6.20. A-2.3. Head-space solid phase micro-extraction- gas

Connection between Stellar Mass Distributions within Galaxies and Quenching Since z = 2

NASA Astrophysics Data System (ADS)

Mosleh, Moein; Tacchella, Sandro; Renzini, Alvio; Carollo, C. Marcella; Molaeinezhad, Alireza; Onodera, Masato; Khosroshahi, Habib G.; Lilly, Simon

2017-03-01

We study the history from z˜ 2 to z˜ 0 of the stellar mass assembly of quiescent and star-forming galaxies in a spatially resolved fashion. For this purpose, we use multi-wavelength imaging data from the Hubble Space Telescope (HST) over the GOODS fields and the Sloan Digital Sky Survey (SDSS) for the local population. We present the radial stellar mass surface density profiles of galaxies with {M}* > {10}10 {M}⊙ , corrected for mass-to-light ratio ({M}* /L) variations, and derive the half-mass-radius (R m ), central stellar mass surface density within 1 kpc ({{{Σ }}}1) and surface density at R m ({{{Σ }}}m) for star-forming and quiescent galaxies and study their evolution with redshift. At fixed stellar mass, the half-mass sizes of quiescent galaxies increase from z˜ 2 to z˜ 0 by a factor of ˜ 3-5, whereas the half-mass sizes of star-forming galaxies increase only slightly, by a factor of ˜2. The central densities {{{Σ }}}1 of quiescent galaxies decline slightly (by a factor of ≲ 1.7) from z˜ 2 to z˜ 0, while for star-forming galaxies {{{Σ }}}1 increases with time, at fixed mass. We show that the central density {{{Σ }}}1 has a tighter correlation with specific star-formation rate (sSFR) than {{{Σ }}}m and for all masses and redshifts galaxies with higher central density are more prone to be quenched. Reaching a high central density ({{{Σ }}}1≳ {10}10 {M}⊙ {{kpc}}2) seems to be a prerequisite for the cessation of star formation, though a causal link between high {{{Σ }}}1 and quenching is difficult to prove and their correlation can have a different origin.

Hubble Space Telescope Star Tracker ad Two-Gyro Control Law Design, Implementation, and On-Orbit Performance. Part 2

NASA Technical Reports Server (NTRS)

VanArsdall, John C.

2005-01-01

The Hubble Space Telescope (HST) normally requires three gyroscopes for three-axis rate control. The loss of the Space Shuttle Columbia on STS-107 resulted in the cancellation of a shuttle-based HST Servicing Mission 4. Therefore, HST must operate using the on-board hardware until an alternate means of servicing can be accomplished. The probability of gyro failure indicates that fewer than three gyros will be operable before any servicing mission can be performe& To mitigate this, and to extend the HST life expectancy, a rate estimation and control algorithm was developed that requires two gyros to measure rate about two axes, with the remaining axis rate estimated using one of three alternate sensors. Three-axis magnetometers (MSS) are used for coarse rate estimation during large maneuvers and during occultations of other sensors. Fixed-Head Star Trackers (FHSTs) are used for rate estimation during safe mode recovery and during transition to science operations. Fine rate estimation during science operations is performed using the Fine Guidance Sensors (FGSs). The FHST mode (T2G) relies on star vectors as measured by the FHSTs to estimate vehicle rate about the axis not measured by the gyros. Since the FHSTs were not designed to estimate body rate, this method involves a unique set of problems that had to be overcome in the final design, such as the effect of FHST break tracks and moving targets on rate estimation. The solutions to these problems, as well as a detailed description of the design and implementation of the rate estimation are presented Also included are the time domain and frequency domain analysis of the T2G control law. A high fidelity HST simulator (HSTSIM) was used to verify T2G performance prior to on-orbit use. Results of these simulations are also presented. Finally, analysis of actual T2G on-orbit test results is presented for design validation.

I Am Not Captain Dunsel! A (Former) Head of an Academic Branch Library Replies to Steven Bell

ERIC Educational Resources Information Center

Redalje, Susanne J.

2009-01-01

For those unfamiliar with Star Trek, "Dunsel" was a term introduced in the episode titled "The Ultimate Computer." It is a term used by Star Fleet cadets to refer to an entity that serves no useful purpose, in this case a human who has been replaced by a machine. The episode touches on finding the best balance between human and machine to run a…

ultra-Stable Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (5STAR)

NASA Astrophysics Data System (ADS)

Dunagan, S. E.; Johnson, R. R.; Redemann, J.; Holben, B. N.; Schmid, B.; Flynn, C. J.; Fahey, L.; LeBlanc, S. E.; Liss, J.; Kacenelenbogen, M. S.; Segal-Rosenhaimer, M.; Shinozuka, Y.; Dahlgren, R. P.; Pistone, K.; Karol, Y.

2017-12-01

The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) combines airborne sun tracking and sky scanning with diffraction spectroscopy to improve knowledge of atmospheric constituents and their links to air pollution and climate. Direct beam hyperspectral measurement of optical depth improves retrievals of gas constituents and determination of aerosol properties. Sky scanning enhances retrievals of aerosol type and size distribution. Hyperspectral cloud-transmitted radiance measurements enable the retrieval of cloud properties from below clouds. These measurements tighten the closure between satellite and ground-based measurements. 4STAR incorporates a modular sun-tracking/ sky-scanning optical head with optical fiber signal transmission to rack mounted spectrometers, permitting miniaturization of the external optical tracking head, and future detector evolution. 4STAR has supported a broad range of flight experiments since it was first flown in 2010. This experience provides the basis for a series of improvements directed toward reducing measurement uncertainty and calibration complexity, and expanding future measurement capabilities, to be incorporated into a new 5STAR instrument. A 9-channel photodiode radiometer with AERONET-matched bandpass filters will be incorporated to improve calibration stability. A wide dynamic range tracking camera will provide a high precision solar position tracking signal as well as an image of sky conditions around the solar axis. An ultrasonic window cleaning system design will be tested. A UV spectrometer tailored for formaldehyde and SO2 gas retrievals will be added to the spectrometer enclosure. Finally, expansion capability for a 4 channel polarized radiometer to measure the Stokes polarization vector of sky light will be incorporated. This paper presents initial progress on this next-generation 5STAR instrument. Keywords: atmosphere; climate; pollution; radiometry; technology; hyperspectral; fiber optic, polarimetry

32 CFR 247.2 - Applicability.

Code of Federal Regulations, 2014 CFR

2014-07-01

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32 CFR 247.2 - Applicability.

Code of Federal Regulations, 2010 CFR

2010-07-01

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32 CFR 247.2 - Applicability.

Code of Federal Regulations, 2011 CFR

2011-07-01

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32 CFR 247.2 - Applicability.

Code of Federal Regulations, 2013 CFR

2013-07-01

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32 CFR 247.2 - Applicability.

Code of Federal Regulations, 2012 CFR

2012-07-01

... DEPARTMENT OF DEFENSE NEWSPAPERS, MAGAZINES AND CIVILIAN ENTERPRISE PUBLICATIONS § 247.2 Applicability. This... Heads of the DoD Components. (b) Does not apply to the Stars and Stripes (S&S) newspapers and business...

Push type fastener

NASA Technical Reports Server (NTRS)

Jackson, Steven A. (Inventor)

1994-01-01

A push type fastener for fastening a movable structural part (41) to a fixed structural part (43), wherein the coupling and decoupling actions are both a push type operation, the fastener consisting of a plunger (12) having a shank (20) with a plunger head (18) at one end and a threaded end portion (26a) at the other end, an expandable grommet (14) adapted to receive the plunger shank (20) therethrough, and an attachable head (16) which is securable to the threaded end of the plunger shank (20). The fastener (10) requires each structural part (41, 43) to be provided with an aperture (45, 46) and the attachable head (16) to be smaller than the aperture (46) in the second structural part. The plunger (12) is extensible through the grommet (14) and is structurally configured with an external camming surface (25) which is cooperatively engageable with internal surfaces (38) of the grommet so that when the plunger is inserted in the grommet, the relative positioning of said cooperable camming surfaces determines the expansion of the grommet. Coupling of the parts is effected when the grommet is inserted in the aperture (46) in the fixed structural part (43) and expanded by pushing the plunger head (18) and plunger at least a minimal distance through the grommet. Decoupling is effected by pushing the attachable head (16).

Visual–Motor Transformations Within Frontal Eye Fields During Head-Unrestrained Gaze Shifts in the Monkey

PubMed Central

Sajad, Amirsaman; Sadeh, Morteza; Keith, Gerald P.; Yan, Xiaogang; Wang, Hongying; Crawford, John Douglas

2015-01-01

A fundamental question in sensorimotor control concerns the transformation of spatial signals from the retina into eye and head motor commands required for accurate gaze shifts. Here, we investigated these transformations by identifying the spatial codes embedded in visually evoked and movement-related responses in the frontal eye fields (FEFs) during head-unrestrained gaze shifts. Monkeys made delayed gaze shifts to the remembered location of briefly presented visual stimuli, with delay serving to dissociate visual and movement responses. A statistical analysis of nonparametric model fits to response field data from 57 neurons (38 with visual and 49 with movement activities) eliminated most effector-specific, head-fixed, and space-fixed models, but confirmed the dominance of eye-centered codes observed in head-restrained studies. More importantly, the visual response encoded target location, whereas the movement response mainly encoded the final position of the imminent gaze shift (including gaze errors). This spatiotemporal distinction between target and gaze coding was present not only at the population level, but even at the single-cell level. We propose that an imperfect visual–motor transformation occurs during the brief memory interval between perception and action, and further transformations from the FEF's eye-centered gaze motor code to effector-specific codes in motor frames occur downstream in the subcortical areas. PMID:25491118

Inertial vestibular coding of motion: concepts and evidence

NASA Technical Reports Server (NTRS)

Hess, B. J.; Angelaki, D. E.

1997-01-01

Central processing of inertial sensory information about head attitude and motion in space is crucial for motor control. Vestibular signals are coded relative to a non-inertial system, the head, that is virtually continuously in motion. Evidence for transformation of vestibular signals from head-fixed sensory coordinates to gravity-centered coordinates have been provided by studies of the vestibulo-ocular reflex. The underlying central processing depends on otolith afferent information that needs to be resolved in terms of head translation related inertial forces and head attitude dependent pull of gravity. Theoretical solutions have been suggested, but experimental evidence is still scarce. It appears, along these lines, that gaze control systems are intimately linked to motor control of head attitude and posture.

Upgrade of the NASA 4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research) to its Full Science Capability of Sun-Sky-Cloud-Trace Gas Spectrometry in Airborne Science Deployments

NASA Technical Reports Server (NTRS)

Johnson, Roy R.; Russell, P.; Dunagan, S.; Redemann, J.; Shinozuka, Y.; Segal-Rosenheimer, M.; LeBlanc, S.; Flynn, C.; Schmid, B.; Livingston, J.

2014-01-01

The objectives of this task in the AITT (Airborne Instrument Technology Transition) Program are to (1) upgrade the NASA 4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research) instrument to its full science capability of measuring (a) direct-beam sun transmission to derive aerosol optical depth spectra, (b) sky radiance vs scattering angle to retrieve aerosol absorption and type (via complex refractive index spectra, shape, and mode-resolved size distribution), (c) zenith radiance for cloud properties, and (d) hyperspectral signals for trace gas retrievals, and (2) demonstrate its suitability for deployment in challenging NASA airborne multiinstrument campaigns. 4STAR combines airborne sun tracking, sky scanning, and zenith pointing with diffraction spectroscopy to improve knowledge of atmospheric constituents and their links to air pollution, radiant energy budgets (hence climate), and remote measurements of Earth's surfaces. Direct beam hyperspectral measurement of optical depth improves retrievals of gas constituents and determination of aerosol properties. Sky scanning enhances retrievals of aerosol type and size distribution. 4STAR measurements are intended to tighten the closure between satellite and ground-based measurements. 4STAR incorporates a modular sun-tracking/sky-scanning optical head with fiber optic signal transmission to rack mounted spectrometers, permitting miniaturization of the external optical head, and future detector evolution. 4STAR test flights, as well as science flights in the 2012-13 TCAP (Two-Column Aerosol Project) and 2013 SEAC4RS (Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys) have demonstrated that the following are essential for 4STAR to achieve its full science potential: (1) Calibration stability for both direct-beam irradiance and sky radiance, (2) Improved light collection and usage, and (3) Improved flight operability and reliability. A particular challenge for the AITT-4STAR project has been conducting it simultaneously with preparations for, and execution of, ARISE (Arctic Radiation - IceBridge Sea&Ice Experiment), a NASA airborne science deployment (unplanned when AITT-4STAR was selected for funding) in which 4STAR will deploy to Thule, Greenland, and Fairbanks, Alaska, on the NASA C- 130. This presentation describes progress to date in accomplishing AITT-4STAR goals, and plans for project completion.

The attitude accuracy consequences of on-orbit calibration of the Extreme Ultraviolet Explorer attitude sensors by the Flight Dynamics Facility at Goddard Space Flight Center

NASA Technical Reports Server (NTRS)

Hashmall, J.; Davis, W.; Harman, R.

1993-01-01

The science mission of the Extreme Ultraviolet Explorer (EUVE) requires attitude solutions with uncertainties of 27, 16.7, 16.7 arcseconds (3 sigma) around the roll, pitch, and yaw axes, respectively. The primary input to the attitude determination process is provided by two NASA standard fixed-head star trackers (FHSTs) and a Teledyne dry rotor inertial reference unit (DRIRU) 2. The attitude determination requirements approach the limits attainable with the FHSTs and DRIRU. The Flight Dynamics Facility (FDF) at Goddard Space Flight Center (GSFC) designed and executed calibration procedures that far exceeded the extent and the data volume of any other FDF-supported mission. The techniques and results of this attempt to obtain attitude accuracies at the limit of sensor capability and the results of analysis of the factors that limit the attitude accuracy are the primary subjects of this paper. The success of the calibration effort is judged by the resulting measurement residuals and comparisons between ground- and onboard-determined attitudes. The FHST star position residuals have been reduced to less tha 4 arcsec per axis -- a value that appears to be limited by the sensor capabilities. The FDF ground system uses a batch least-squares estimator to determine attitude. The EUVE onboard computer (OBC) uses an extended Kalman filter. Currently, there are systematic differences between the two attitude solutions that occasionally exceed the mission requirements for 3 sigma attitude uncertainty. Attempts to understand and reduce these differences are continuing.

Small Orbital Stereo Tracking Camera Technology Development

NASA Technical Reports Server (NTRS)

Bryan, Tom; MacLeod, Todd; Gagliano, Larry

2017-01-01

Any exploration vehicle assembled or Spacecraft placed in LEO or GTO must pass through this debris cloud and survive. Large cross section, low thrust vehicles will spend more time spiraling out through the cloud and will suffer more impacts.Better knowledge of small debris will improve survival odds. Current estimated Density of debris at various orbital attitudes with notation of recent collisions and resulting spikes. Orbital Debris Tracking and Characterization has now been added to NASA Office of Chief Technologists Technology Development Roadmap in Technology Area 5 (TA5.7)[Orbital Debris Tracking and Characterization] and is a technical gap in the current National Space Situational Awareness necessary to safeguard orbital assets and crews due to the risk of Orbital Debris damage to ISS Exploration vehicles. The Problem: Traditional orbital trackers looking for small, dim orbital derelicts and debris typically will stare at the stars and let any reflected light off the debris integrate in the imager for seconds, thus creating a streak across the image. The Solution: The Small Tracker will see Stars and other celestial objects rise through its Field of View (FOV) at the rotational rate of its orbit, but the glint off of orbital objects will move through the FOV at different rates and directions. Debris on a head-on collision course (or close) will stay in the FOV at 14 Km per sec. The Small Tracker can track at 60 frames per sec allowing up to 30 fixes before a near-miss pass. A Stereo pair of Small Trackers can provide range data within 5-7 Km for better orbit measurements.

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'Witch Head' Brews Baby Stars

NASA Image and Video Library

2015-10-30

A witch appears to be screaming out into space in this new image from NASA's Wide-Field Infrared Survey Explorer, or WISE. The infrared portrait shows the Witch Head nebula, named after its resemblance to the profile of a wicked witch. Astronomers say the billowy clouds of the nebula, where baby stars are brewing, are being lit up by massive stars. Dust in the cloud is being hit with starlight, causing it to glow with infrared light, which was picked up by WISE's detectors. The Witch Head nebula is estimated to be hundreds of light-years away in the Orion constellation, just off the famous hunter's knee. WISE was recently "awakened" to hunt for asteroids in a program called NEOWISE. The reactivation came after the spacecraft was put into hibernation in 2011, when it completed two full scans of the sky, as planned. Image credit: NASA/JPL-Caltech NASA image use policy. ( http://www.nasa.gov/audience/formedia/features/MP_Photo_Guidelines.html ) NASA Goddard Space Flight Center ( http://www.nasa.gov/centers/goddard/home/index.html ) enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter ( http://twitter.com/NASA_GoddardPix ) Like us on Facebook ( http://www.facebook.com/pages/Greenbelt-MD/NASA-Goddard/395013845897?ref=tsd ) Find us on Instagram ( http://instagram.com/nasagoddard?vm=grid )

By Draconis Stars

NASA Astrophysics Data System (ADS)

Bopp, Bernard W.

An optical spectroscopic survey of dK-M stars has resulted in the discovery of several new H-alpha emission objects. Available optical data suggest these stars have a level of chromospheric activity midway between active BY Dra stars and quiet dM's. These "marginal" BY Dra stars are single objects that have rotation velocities slightly higher than that of quiet field stars but below that of active flare/BY Dra objects. The marginal BY Dra stars provide us with a class of objects rotating very near a "trigger velocity" (believed to be 5 km/s) which appears to divide active flare/BY Dra stars from quiet dM's. UV data on Mg II emission fluxes and strength of transition region features such as C IV will serve to fix activity levels in the marginal objects and determine chromosphere and transition-region heating rates. Simultaneous optical magnetic field measures will be used to explore the connection between fieldstrength/filling-factor and atmospheric heating. Comparison of these data with published information on active and quiet dM stars will yield information on the character of the stellar dynamo as it makes a transition from "low" to "high" activity.

Axis of Eye Rotation Changes with Head-Pitch Orientation during Head Impulses about Earth-Vertical

PubMed Central

Schubert, Michael C.; Clendaniel, Richard A.; Carey, John P.; Della Santina, Charles C.; Minor, Lloyd B.; Zee, David S.

2006-01-01

The goal of this study was to assess how the axis of head rotation, Listing's law, and eye position influence the axis of eye rotation during brief, rapid head rotations. We specifically asked how the axis of eye rotation during the initial angular vestibuloocular reflex (VOR) changed when the pitch orientation of the head relative to Earth-vertical was varied, but the initial position of the eye in the orbit and the orientation of Listing's plane with respect to the head were fixed. We measured three-dimensional eye and head rotation axes in eight normal humans using the search coil technique during head-and-trunk (whole-body) and head-on-trunk (head-only) “impulses” about an Earth-vertical axis. The head was initially oriented at one of five pitch angles (30° nose down, 15° nose down, 0°, 15° nose up, 30° nose up). The fixation target was always aligned with the nasooccipital axis. Whole-body impulses were passive, unpredictable, manual, rotations with peak-amplitude of ∼20°, peak-velocity of ∼80°/s, and peak-acceleration of ∼1000°/s2. Head-only impulses were also passive, unpredictable, manual, rotations with peak-amplitude of ∼20°, peak-velocity of ∼150°/s, and peak-acceleration of ∼3000°/s2. During whole-body impulses, the axis of eye rotation tilted in the same direction, and by an amount proportional (0.51 ± 0.09), to the starting pitch head orientation (P < 0.05). This proportionality constant decreased slightly to 0.39 ± 0.08 (P < 0.05) during head-only impulses. Using the head-only impulse data, with the head pitched up, we showed that only 50% of the tilt in the axis of eye rotation could be predicted from vectorial summation of the gains (eye velocity/head velocity) obtained for rotations about the pure yaw and roll head axes. Thus, even when the orientation of Listing's plane and eye position in the orbit are fixed, the axis of eye rotation during the VOR reflects a compromise between the requirements of Listing's law and a perfectly compensatory VOR. PMID:16552499

Relative likelihood for life as a function of cosmic time

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

Loeb, Abraham; Batista, Rafael A.; Sloan, David, E-mail: aloeb@cfa.harvard.edu, E-mail: rafael.alvesbatista@physics.ox.ac.uk, E-mail: david.sloan@physics.ox.ac.uk

2016-08-01

Is life most likely to emerge at the present cosmic time near a star like the Sun? We address this question by calculating the relative formation probability per unit time of habitable Earth-like planets within a fixed comoving volume of the Universe, dP ( t )/ dt , starting from the first stars and continuing to the distant cosmic future. We conservatively restrict our attention to the context of ''life as we know it'' and the standard cosmological model, ΛCDM . We find that unless habitability around low mass stars is suppressed, life is most likely to exist near ∼more » 0.1 M {sub ⊙} stars ten trillion years from now. Spectroscopic searches for biosignatures in the atmospheres of transiting Earth-mass planets around low mass stars will determine whether present-day life is indeed premature or typical from a cosmic perspective.« less

From Head to Sword: The Clustering Properties of Stars in Orion

NASA Astrophysics Data System (ADS)

Gomez, Mercedes; Lada, Charles J.

1998-04-01

We investigate the structure in the spatial distributions of optically selected samples of young stars in the Head (lambda Orionis) and in the Sword (Orion A) regions of the constellation of Orion with the aid of stellar surface density maps and the two-point angular correlation function. The distributions of young stars in both regions are found to be nonrandom and highly clustered. Stellar surface density maps reveal three distinct clusters in the lambda Ori region. The two-point correlation function displays significant features at angular scales that correspond to the radii and separations of the three clusters identified in the surface density maps. Most young stars in the lambda Ori region (~80%) are presently found within these three clusters, consistent with the idea that the majority of young stars in this region were formed in dense protostellar clusters that have significantly expanded since their formation. Over a scale of ~0.05d-0.5d the correlation function is well described by a single power law that increases smoothly with decreasing angular scale. This suggests that, within the clusters, the stars either are themselves hierarchically clustered or have a volume density distribution that falls steeply with radius. The relative lack of Hα emission-line stars in the one cluster in this region that contains OB stars suggests a timescale for emission-line activity of less than 4 Myr around late-type stars in the cluster and may indicate that the lifetimes of protoplanetary disks around young stellar objects are reduced in clusters containing O stars. The spatial distribution of young stars in the Orion A region is considerably more complex. The angular correlation function of the OB stars (which are mostly foreground to the Orion A molecular cloud) is very similar to that of the Hα stars (which are located mostly within the molecular cloud) and significantly different from that of the young stars in the lambda Ori region. This suggests that, although spatially separated, both populations in the Orion A region may have originated from a similar fragmentation process. Stellar surface density maps and modeling of the angular correlation function suggest that somewhat less than half of the OB and Hα stars in the Orion A cloud are presently within well-defined stellar clusters. Although all the OB stars could have originated in rich clusters, a significant fraction of the Hα stars appear to have formed outside such clusters in a more spatially dispersed manner. The close similarity of the angular correlation functions of the OB and Hα stars toward the molecular cloud, in conjunction with the earlier indications of a relatively high star formation rate and high gas pressure in this cloud, is consistent with the idea that older, foreground OB stars triggered the current episode of star formation in the Orion A cloud. One of the OB clusters (Upper Sword) that is foreground to the cloud does not appear to be associated with any of the clusterings of emission-line stars, again suggesting a timescale (<4 Myr) for emission-line activity and disk lifetimes around late-type stars born in OB clusters.

Maximum Mass of Hybrid Stars in the Quark Bag Model

NASA Astrophysics Data System (ADS)

Alaverdyan, G. B.; Vartanyan, Yu. L.

2017-12-01

The effect of model parameters in the equation of state for quark matter on the magnitude of the maximum mass of hybrid stars is examined. Quark matter is described in terms of the extended MIT bag model including corrections for one-gluon exchange. For nucleon matter in the range of densities corresponding to the phase transition, a relativistic equation of state is used that is calculated with two-particle correlations taken into account based on using the Bonn meson-exchange potential. The Maxwell construction is used to calculate the characteristics of the first order phase transition and it is shown that for a fixed value of the strong interaction constant αs, the baryon concentrations of the coexisting phases grow monotonically as the bag constant B increases. It is shown that for a fixed value of the strong interaction constant αs, the maximum mass of a hybrid star increases as the bag constant B decreases. For a given value of the bag parameter B, the maximum mass rises as the strong interaction constant αs increases. It is shown that the configurations of hybrid stars with maximum masses equal to or exceeding the mass of the currently known most massive pulsar are possible for values of the strong interaction constant αs > 0.6 and sufficiently low values of the bag constant.

Synthetic nebular emission from massive galaxies - I: origin of the cosmic evolution of optical emission-line ratios

NASA Astrophysics Data System (ADS)

Hirschmann, Michaela; Charlot, Stephane; Feltre, Anna; Naab, Thorsten; Choi, Ena; Ostriker, Jeremiah P.; Somerville, Rachel S.

2017-12-01

Galaxies occupy different regions of the [O III]λ5007/H β-versus-[N II]λ6584/H α emission-line ratio diagram in the distant and local Universe. We investigate the origin of this intriguing result by modelling self-consistently, for the first time, nebular emission from young stars, accreting black holes (BHs) and older, post-asymptotic giant branch (post-AGB) stellar populations in galaxy formation simulations in a full cosmological context. In post-processing, we couple new-generation nebular-emission models with high-resolution, cosmological zoom-in simulations of massive galaxies to explore which galaxy physical properties drive the redshift evolution of the optical-line ratios [O III]λ5007/H β, [N II]λ6584/H α, [S II]λλ6717, 6731/H α and [O I]λ6300/H α. The line ratios of simulated galaxies agree well with observations of both star-forming and active local Sloan Digital Sky Survey galaxies. Towards higher redshifts, at fixed galaxy stellar mass, the average [O III]/H β is predicted to increase and [N II]/H α, [S II]/H α and [O I]/H α to decrease - widely consistent with observations. At fixed stellar mass, we identify star formation history, which controls nebular emission from young stars via the ionization parameter, as the primary driver of the cosmic evolution of [O III]/H β and [N II]/H α. For [S II]/H α and [O I]/H α, this applies only to redshifts greater than z = 1.5, the evolution at lower redshift being driven in roughly equal parts by nebular emission from active galactic nuclei and post-AGB stellar populations. Instead, changes in the hardness of ionizing radiation, ionized-gas density, the prevalence of BH accretion relative to star formation and the dust-to-metal mass ratio (whose impact on the gas-phase N/O ratio we model at fixed O/H) play at most a minor role in the cosmic evolution of simulated galaxy line ratios.

Polar orbits around binary stars

NASA Astrophysics Data System (ADS)

Egan, Greg

2018-01-01

Oks proposes the existence of a new class of stable planetary orbits around binary stars, in the shape of a helix on a conical surface whose axis of symmetry coincides with the interstellar axis, and rotates with the same orbital frequency as the binary pair. We show that this claim relies on the inappropriate use of an effective potential that is only applicable when the stars are held motionless. We also present numerical evidence that the only planetary orbits whose planes are initially orthogonal to the interstellar axis that remain stable on the time scale of the stellar orbit are ordinary polar orbits around one of the stars, and that the perturbations due to the binary companion do not rotate the plane of the orbit to maintain a fixed relationship with the axis.

Revising the Evolutionary Stage of HD 163899: The Effects of Convective Overshooting and Rotation

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

Ostrowski, Jakub; Daszyńska-Daszkiewicz, Jadwiga; Cugier, Henryk, E-mail: ostrowski@astro.uni.wroc.pl

We revise the evolutionary status of the B-type supergiant HD 163899 based on the new determinations of the mass–luminosity ratio, effective temperature, and rotational velocity, as well as on the interpretation of the oscillation spectrum of the star. The observed value of the nitrogen-to-carbon abundance fixes the value of the rotation rate of the star. Now, more massive models are strongly preferred than those previously considered, and it is very likely that the star is still in the main-sequence stage. The rotationally induced mixing manifests as the nitrogen overabundance in the atmosphere, which agrees with our analysis of the HARPSmore » spectra. Thus, HD 163899 probably belongs to a group of evolved nitrogen-rich main-sequence stars.« less

Anomalous hydrodynamics kicks neutron stars

DOE PAGES

Kaminski, Matthias; Uhlemann, Christoph F.; Bleicher, Marcus; ...

2016-06-28

Observations show that, at the beginning of their existence, neutron stars are accelerated briskly to velocities of up to a thousand kilometers per second. We argue that this remarkable effect can be explained as a manifestation of quantum anomalies on astrophysical scales. To theoretically describe the early stage in the life of neutron stars we use hydrodynamics as a systematic effective-field-theory framework. Within this framework, anomalies of the Standard Model of particle physics as underlying microscopic theory imply the presence of a particular set of transport terms, whose form is completely fixed by theoretical consistency. Here, the resulting chiral transportmore » effects in proto-neutron stars enhance neutrino emission along the internal magnetic field, and the recoil can explain the order of magnitude of the observed kick velocities.« less

Head sway response to optic flow: effect of age is more important than the presence of unilateral vestibular hypofunction

PubMed Central

Sparto, Patrick J.; Furman, Joseph M.; Redfern, Mark S.

2014-01-01

Background The purpose of this study was to examine how older adults with vestibular impairment use sensory feedback for postural control. Methods Nine older adult subjects with unilateral vestibular hypofunction (UVH, mean age 69 y) and 14 older (mean age 70 y) and 8 young adult controls (CON, mean age 28 y) viewed full-field optic flow scenes while standing on a fixed or sway-referenced support surface. The subjects with UVH had 100% caloric asymmetry. Optic flow consisted of sinusoidal anterior-posterior movement of the visual surround at three frequencies and three amplitudes of stimulation. The anterior-posterior head sway was measured. The number of head sway responses that were coupled to the optic flow and magnitude of head sway during optic flow relative to during quiet stance on fixed floor was quantified. Results The number of trials in which the head sway response was significantly coupled to the optic flow was significantly greater in the Older UVH and Older CON subjects compared with the Young CON subjects. Furthermore, the magnitude of head sway was two to three times greater in Older UVH and CON compared with Young CON subjects. There was no difference in coupling or magnitude of head sway between Older UVH and Older CON subjects. The amplitude of sway was also dependent on the amount of surface support, stimulus frequency, and stimulus amplitude. Conclusions Older adults with unilateral vestibular hypofunction who are able to effectively compensate show no difference in postural responses elicited by optic flow compared with age-matched controls. PMID:17312341

Enhancing the reproducibility of ocular vestibular evoked myogenic potentials by use of a visual target originating from a head-mounted laser.

PubMed

Jerin, Claudia; Bartl, Klaus; Schneider, Erich; Gürkov, Robert

2015-10-01

Ocular vestibular evoked myogenic potentials (oVEMPs) represent extraocular muscle activity in response to vestibular stimulation. oVEMP amplitudes are known to increase with increasing upward gaze angle, while the patient fixates a visual target. We investigated two different methods of presenting a visual target during oVEMP recordings. 57 healthy subjects were enrolled in this study. oVEMPs were elicited by 500 Hz air-conducted tone bursts while the subjects were looking upward at a marking which was either fixed on the wall or originated from a head-mounted laser attached to a headband, in either case corresponding to a 35° upward gaze angle. oVEMP amplitudes and latencies did not differ between the subjects looking at the fixed marking and the ones looking at the laser marking. The intra-individual standard deviation of amplitudes obtained by two separate measurements for each subject, however, as a measure of test-retest reliability, was significantly smaller for the laser headband group (0.60) in comparison to the group looking at the fixed marking (0.96; p = 0.007). The intraclass correlation coefficient revealed better test-retest reliability for oVEMP amplitudes when using the laser headband (0.957) than using the fixed marking (0.908). Hence, the use of a visual target originating from a headband enhances the reproducibility of oVEMPs. This might be due to the fact that the laser headband ensures a constant gaze angle and rules out the influence of small involuntary head movements on the gaze angle.

Visual-Vestibular Conflict Detection Depends on Fixation.

PubMed

Garzorz, Isabelle T; MacNeilage, Paul R

2017-09-25

Visual and vestibular signals are the primary sources of sensory information for self-motion. Conflict among these signals can be seriously debilitating, resulting in vertigo [1], inappropriate postural responses [2], and motion, simulator, or cyber sickness [3-8]. Despite this significance, the mechanisms mediating conflict detection are poorly understood. Here we model conflict detection simply as crossmodal discrimination with benchmark performance limited by variabilities of the signals being compared. In a series of psychophysical experiments conducted in a virtual reality motion simulator, we measure these variabilities and assess conflict detection relative to this benchmark. We also examine the impact of eye movements on visual-vestibular conflict detection. In one condition, observers fixate a point that is stationary in the simulated visual environment by rotating the eyes opposite head rotation, thereby nulling retinal image motion. In another condition, eye movement is artificially minimized via fixation of a head-fixed fixation point, thereby maximizing retinal image motion. Visual-vestibular integration performance is also measured, similar to previous studies [9-12]. We observe that there is a tradeoff between integration and conflict detection that is mediated by eye movements. Minimizing eye movements by fixating a head-fixed target leads to optimal integration but highly impaired conflict detection. Minimizing retinal motion by fixating a scene-fixed target improves conflict detection at the cost of impaired integration performance. The common tendency to fixate scene-fixed targets during self-motion [13] may indicate that conflict detection is typically a higher priority than the increase in precision of self-motion estimation that is obtained through integration. Copyright © 2017 Elsevier Ltd. All rights reserved.

ON THE BIRTH MASSES OF THE ANCIENT GLOBULAR CLUSTERS

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

Conroy, Charlie; Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA

All globular clusters (GCs) studied to date show evidence for internal (star-to-star) variation in their light-element abundances (including Li, C, N, O, F, Na, Mg, Al, and probably He). These variations have been interpreted as evidence for multiple star formation episodes within GCs, with secondary episodes fueled, at least in part, by the ejecta of asymptotic giant branch (AGB) stars from a first generation of stars. A major puzzle emerging from this otherwise plausible scenario is that the fraction of stars associated with the second episode of star formation is observed to be much larger than expected for a standardmore » initial mass function. The present work investigates this tension by modeling the observed anti-correlation between [Na/Fe] and [O/Fe] for 20 Galactic GCs. If the abundance pattern of the retained AGB ejecta does not depend on GC mass at fixed [Fe/H], then a strong correlation is found between the fraction of current GC stellar mass composed of pure AGB ejecta, f{sub p} , and GC mass. This fraction varies from 0.20 at low masses (10{sup 4.5} M{sub Sun }) to 0.45 at high masses (10{sup 6.5} M{sub Sun }). The fraction of mass associated with pure AGB ejecta is directly related to the total mass of the cluster at birth; the ratio between the initial and present mass in stars can therefore be derived. Assuming a star formation efficiency of 50%, the observed Na-O anti-correlations imply that GCs were at least 10-20 times more massive at birth, a conclusion that is in qualitative agreement with previous work. These factors are lower limits because any mass-loss mechanism that removes first- and second-generation stars equally will leave f{sub p} unchanged. The mass dependence of f{sub p} probably arises because lower mass GCs are unable to retain all of the AGB ejecta from the first stellar generation. Recent observations of elemental abundances in intermediate-age Large Magellanic Cloud clusters are re-interpreted and shown to be consistent with this basic scenario. The small scatter in f{sub p} at fixed GC mass argues strongly that the process responsible for the large mass loss is internal to GCs. A satisfactory explanation of these trends is currently lacking.« less

The Relative Contribution of Interaural Time and Magnitude Cues to Dynamic Sound Localization

NASA Technical Reports Server (NTRS)

Wenzel, Elizabeth M.; Null, Cynthia H. (Technical Monitor)

1995-01-01

This paper presents preliminary data from a study examining the relative contribution of interaural time differences (ITDs) and interaural level differences (ILDs) to the localization of virtual sound sources both with and without head motion. The listeners' task was to estimate the apparent direction and distance of virtual sources (broadband noise) presented over headphones. Stimuli were synthesized from minimum phase representations of nonindividualized directional transfer functions; binaural magnitude spectra were derived from the minimum phase estimates and ITDs were represented as a pure delay. During dynamic conditions, listeners were encouraged to move their heads; the position of the listener's head was tracked and the stimuli were synthesized in real time using a Convolvotron to simulate a stationary external sound source. ILDs and ITDs were either correctly or incorrectly correlated with head motion: (1) both ILDs and ITDs correctly correlated, (2) ILDs correct, ITD fixed at 0 deg azimuth and 0 deg elevation, (3) ITDs correct, ILDs fixed at 0 deg, 0 deg. Similar conditions were run for static conditions except that none of the cues changed with head motion. The data indicated that, compared to static conditions, head movements helped listeners to resolve confusions primarily when ILDs were correctly correlated, although a smaller effect was also seen for correct ITDs. Together with the results for static conditions, the data suggest that localization tends to be dominated by the cue that is most reliable or consistent, when reliability is defined by consistency over time as well as across frequency bands.

The flow field investigations of no load conditions in axial flow fixed-blade turbine

NASA Astrophysics Data System (ADS)

Yang, J.; Gao, L.; Wang, Z. W.; Zhou, X. Z.; Xu, H. X.

2014-03-01

During the start-up process, the strong instabilities happened at no load operation in a low head axial flow fixed-blade turbine, with strong pressure pulsation and vibration. The rated speed can not reach until guide vane opening to some extent, and stable operation could not be maintained under the rated speed at some head, which had a negative impact on the grid-connected operation of the unit. In order to find the reason of this phenomenon, the unsteady flow field of the whole flow passage at no load conditions was carried out to analyze the detailed fluid field characteristics including the pressure pulsation and force imposed on the runner under three typical heads. The main hydraulic cause of no load conditions instability was described. It is recommended that the power station should try to reduce the no-load running time and go into the high load operation as soon as possible when connected to grid at the rated head. Following the recommendations, the plant operation practice proved the unstable degree of the unit was reduced greatly during start up and connect to the power grid.

Towards a 1000 tracks digital tape recorder

NASA Technical Reports Server (NTRS)

Coutellier, J. M.; Castera, J. P.; Colineau, J.; Lehureau, J. C.; Maurice, F.; Hanna, C.

1993-01-01

As the demand for high data rate (up to 1 Gb/s), high density (down to 1 sq micron/bit) tape recorder increases, the main investigation trend is an improvement of the well known helical scan concept. The drawbacks of this technology are also well known; sophisticated mechanics, head to tape contact, and wear problems. In our fixed head approach, the recorder mechanics is made much more simple, but the complexity is turned towards the integrated magnetic components, which have to record and reproduce hundreds of tracks in parallel. Our multiplexed write inductive head and magneto-optical readout head will be described, and the global system performances evaluated.

Domains of pulsational instability of low-frequency modes in rotating upper main sequence stars

NASA Astrophysics Data System (ADS)

Szewczuk, Wojciech; Daszyńska-Daszkiewicz, Jadwiga

2017-07-01

We determine instability domains on the Hertzsprung-Russell diagram for rotating main sequence stars with masses of 2-20 M⊙. The effects of the Coriolis force are treated wihin the traditional approximation. High-order g modes with harmonic degrees ℓ up to 4 and mixed gravity-Rossby modes with |m| up to 4 are considered. We include the effects of rotation in wider instability strips for a given ℓ compared to the non-rotating case and in an extension of the pulsational instability to hotter and more massive models. We present results for a fixed value of the initial rotation velocity as well as for a fixed ratio of the angular rotation frequency to its critical value. Moreover, we check how the initial hydrogen abundance, metallicity, overshooting from the convective core and opacity affect the pulsational instability domains. The effect of rotation on the period spacing is also discussed.

Separation dynamics of the COMET FreeFlyer and an upper stage STAR-48V motor

NASA Technical Reports Server (NTRS)

Fuller, Kevin M.; Myers, Carter H.

1993-01-01

In this report, the orbital separation between a STAR-48V upperstage motor and the COMET FreeFlyer is investigated. The time from nominal STAR-48 engine burnout is to be determined such that the STAR-48 will not collide with the FreeFlyer once the separation process has been initiated. To analyze this separation, the forces acting upon both the FreeFlyer and the STAR-48 are described in a body fixed coordinate system. These coordinates are then transformed into an Euler coordinate system and then further transformed into a relative inertial coordinate system. From this analysis and some basic assumptions about the Star-48/FreeFlyer vehicle, it can be concluded that the STAR-48 will not collide with the Free Flyer if the separation occurs at 120 seconds after nominal burnout of the STAR-48. In fact, the separation delay could be a shorter period of time, but it is recommended that this separation delay be as long as possible for risk mitigation. This delay is currently designed to be 120 seconds and the analysis presented in this report shows that this time is acceptable.

Rapidly rotating neutron stars in general relativity: Realistic equations of state

NASA Technical Reports Server (NTRS)

Cook, Gregory B.; Shapiro, Stuart L.; Teukolsky, Saul A.

1994-01-01

We construct equilibrium sequences of rotating neutron stars in general relativity. We compare results for 14 nuclear matter equations of state. We determine a number of important physical parameters for such stars, including the maximum mass and maximum spin rate. The stability of the configurations to quasi-radial perturbations is assessed. We employ a numerical scheme particularly well suited to handle rapid rotation and large departures from spherical symmetry. We provide an extensive tabulation of models for future reference. Two classes of evolutionary sequences of fixed baryon rest mass and entropy are explored: normal sequences, which behave very much like Newtonian sequences, and supramassive sequences, which exist for neutron stars solely because of general relativistic effects. Adiabatic dissipation of energy and angular momentum causes a star to evolve in quasi-stationary fashion along an evolutionary sequence. Supramassive sequences have masses exceeding the maximum mass of a nonrotating neutron star. A supramassive star evolves toward eventual catastrophic collapse to a black hole. Prior to collapse, the star actually spins up as it loses angular momentum, an effect that may provide an observable precursor to gravitational collapse to a black hole.

Hubble Reveals Stellar Fireworks in ‘Skyrocket’ Galaxy

NASA Image and Video Library

2017-12-08

Fireworks shows are not just confined to Earth’s skies. NASA’s Hubble Space Telescope has captured a spectacular fireworks display in a small, nearby galaxy, which resembles a July 4th skyrocket. A firestorm of star birth is lighting up one end of the diminutive galaxy Kiso 5639. The dwarf galaxy is shaped like a flattened pancake, but because it is tilted edge-on, it resembles a skyrocket, with a brilliant blazing head and a long, star-studded tail. Kiso 5639 is a rare, nearby example of elongated galaxies that occur in abundance at larger distances, where we observe the universe during earlier epochs. Astronomers suggest that the frenzied star birth is sparked by intergalactic gas raining on one end of the galaxy as it drifts through space. “I think Kiso 5639 is a beautiful, up-close example of what must have been common long ago,” said lead researcher Debra Elmegreen of Vassar College, in Poughkeepsie, New York. “The current thinking is that galaxies in the early universe grow from accreting gas from the surrounding neighborhood. It’s a stage that galaxies, including our Milky Way, must go through as they are growing up.” Observations of the early universe, such as Hubble’s Ultra-Deep Field, reveal that about 10 percent of all galaxies have these elongated shapes, and are collectively called “tadpoles.” But studies of the nearby universe have turned up only a few of these unusual galaxies, including Kiso 5639. The development of the nearby star-making tadpole galaxies, however, has lagged behind that of their peers, which have spent billions of years building themselves up into many of the spiral galaxies seen today. Elmegreen used Hubble’s Wide Field Camera 3 to conduct a detailed imaging study of Kiso 5639. The images in different filters reveal information about an object by dissecting its light into its component colors. Hubble’s crisp resolution helped Elmegreen and her team analyze the giant star-forming clumps in Kiso 5639 and determine the masses and ages of the star clusters. The international team of researchers selected Kiso 5639 from a spectroscopic survey of 10 nearby tadpole galaxies, observed with the Grand Canary Telescope in La Palma, Spain, by Jorge Sanchez Almeida and collaborators at the Instituto de Astrofisica de Canarias. The observations revealed that in most of those galaxies, including Kiso 5639, the gas composition is not uniform. The bright gas in the galaxy’s head contains fewer heavier elements (collectively called “metals”), such as carbon and oxygen, than the rest of the galaxy. Stars consist mainly of hydrogen and helium, but cook up other “heavier” elements. When the stars die, they release their heavy elements and enrich the surrounding gas. “The metallicity suggests that there has to be rather pure gas, composed mostly of hydrogen, coming into the star-forming part of the galaxy, because intergalactic space contains more pristine hydrogen-rich gas,” Elmegreen explained. “Otherwise, the starburst region should be as rich in heavy elements as the rest of the galaxy.” Hubble offers a detailed view of the galaxy’s star-making frenzy. The telescope uncovered several dozen clusters of stars in the galaxy’s star-forming head, which spans 2,700 light-years across. These clusters have an average age of less than 1 million years and masses that are three to six times larger than those in the rest of the galaxy. Other star formation is taking place throughout the galaxy but on a much smaller scale. Star clusters in the rest of the galaxy are between several million to a few billion years old. “There is much more star formation going on in the head than what you would expect in such a tiny galaxy,” said team member Bruce Elmegreen of IBM’s Thomas J. Watson’s Research Center, in Yorktown Heights, New York. “And we think the star formation is triggered by the ongoing accretion of metal-poor gas onto a part of an otherwise quiescent dwarf galaxy.” Hubble also revealed giant holes peppered throughout the galaxy’s starburst head. These cavities give the galaxy’s head a Swiss-cheese appearance because numerous supernova detonations – like firework aerial bursts – have carved out holes of rarified superheated gas. The galaxy, located 82 million light-years away, has taken billions of years to develop because it has been drifting through an isolated “desert” in the universe, devoid of much gas. What triggered the starburst in such a backwater galaxy? Based on simulations by Daniel Ceverino of the Center for Astronomy at Heidelberg University in Germany, and other team members, the observations suggest that less than 1 million years ago, Kiso 5639’s leading edge encountered a filament of gas. The filament dropped a large clump of matter onto the galaxy, stoking the vigorous star birth. Debra Elmegreen expects that in the future other parts of the galaxy will join in the star-making fireworks show. “Galaxies rotate, and as Kiso 5639 continues to spin, another part of the galaxy may receive an infusion of new gas from this filament, instigating another round of star birth,” she said. The team’s results have been accepted for publication in The Astrophysical Journal. Other team members include Casiana Munoz-Tunon and Mercedes Filho (Instituto de Astrofísica de Canarias, Canary Islands), Jairo Mendez-Abreu (University of St. Andrews, United Kingdom), John Gallagher (University of Wisconsin-Madison), and Marc Rafelski (NASA's Goddard Space Flight Center, Greenbelt, Maryland). The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C. For images and more information about Kiso 5639 and Hubble, visit: hubblesite.org/news/2016/23 www.nasa.gov/hubble Image credit: NASA, ESA, and D. Elmegreen (Vassar College) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Maximising Defence Capability Through R&D: A Review of Defence Research and Development

DTIC Science & Technology

2007-10-01

Armoured Armoured Fighting Fighting Vehicles Vehicles Other 2.0% C41STAR Other 2.4% C41STAR 10.2% CBRN 5.4% Fixed Wing General Helicopters No DIS Sector... Armoured Trials Development Unit and with operational units deployed in Iraq. The Commanding Officer of the operational unit reported that the camera...other organisations, while high staff- turnover risks a lack of awareness of background R&D sponsored previously within the IPT. As a result, IPTs

Christoph Rothmann's compendium of astronomy of 1589. (German Title: Christoph Rothmanns Handbuch der Astronomie von 1589)

NASA Astrophysics Data System (ADS)

Granada, Miguel A.; Hamel, Jürgen; von Mackensen, Ludolf

Around 1560, landgrave William IV. founded on his Cassel castle the first permanent observatory of modern times in Europe, and started to occupy himself with systematic sky observations. From the beginning, the main interest was focussed on the fixed stars, since William had recognized that exact position determinations were a prerequisite for further progress in astronomy. The observatory personnel was enlarged, in 1579, by the mathematician, clock-maker and instrument-maker Jost Bürgi, and in 1584 by the practical astronomer Christoph Rothmann. Since that time, intense work was carried out by creating a catalogue of fixed stars, based on own observations, which was completed in 1589. The accuracy of its stellar positions had not been reached in the past, and even superseded that of the almost contemporary catalogue by Tycho Brahe. Research in theoretical astronomy and cosmology at the landgrave's court in Cassel was also revolutionary: the acceptance of the heliocentric world system, investigations on refraction, the dismissal of the concept of solid planetary spheres and even that of a world ether, the nature of cometary tails, etc. Christoph Rothmann's work, edited here for the first time on the basis of the original manuscript, had been drafted as a commentary or introduction to his catalogue of fixed stars. He describes the construction and use of astronomical instruments, he unfolds his concepts of the system of the world on a heliocentric basis without solid planetary spheres to which he was lead by his research on refraction, he discusses the relation between astronomy and theology, and describes his revolutionary work on the Cassel star catalogue. This work constitutes a compendium of theoretical and practical astronomy of the late 16th century whose major scientific importance lies in the fact that it achieves scientific excellence in its time both because of the multitude of topics and because of the high level of discussion.

Visual-Motor Transformations Within Frontal Eye Fields During Head-Unrestrained Gaze Shifts in the Monkey.

PubMed

Sajad, Amirsaman; Sadeh, Morteza; Keith, Gerald P; Yan, Xiaogang; Wang, Hongying; Crawford, John Douglas

2015-10-01

A fundamental question in sensorimotor control concerns the transformation of spatial signals from the retina into eye and head motor commands required for accurate gaze shifts. Here, we investigated these transformations by identifying the spatial codes embedded in visually evoked and movement-related responses in the frontal eye fields (FEFs) during head-unrestrained gaze shifts. Monkeys made delayed gaze shifts to the remembered location of briefly presented visual stimuli, with delay serving to dissociate visual and movement responses. A statistical analysis of nonparametric model fits to response field data from 57 neurons (38 with visual and 49 with movement activities) eliminated most effector-specific, head-fixed, and space-fixed models, but confirmed the dominance of eye-centered codes observed in head-restrained studies. More importantly, the visual response encoded target location, whereas the movement response mainly encoded the final position of the imminent gaze shift (including gaze errors). This spatiotemporal distinction between target and gaze coding was present not only at the population level, but even at the single-cell level. We propose that an imperfect visual-motor transformation occurs during the brief memory interval between perception and action, and further transformations from the FEF's eye-centered gaze motor code to effector-specific codes in motor frames occur downstream in the subcortical areas. © The Author 2014. Published by Oxford University Press.

Biomechanics of head injury in olympic taekwondo and boxing.

PubMed

Fife, G P; O'Sullivan, D; Pieter, W

2013-12-01

The purpose was to examine differences between taekwondo kicks and boxing punches in resultant linear head acceleration (RLA), head injury criterion (HIC15), peak head velocity, and peak foot and fist velocities. Data from two existing publications on boxing punches and taekwondo kicks were compared. For taekwondo head impacts a Hybrid II Crash Dummy (Hybrid II) head was instrumented with a tri-axial accelerometer mounted inside the Hybrid II head. The Hybrid II was fixed to a height-adjustable frame and fitted with a protective taekwondo helmet. For boxing testing, a Hybrid III Crash Dummy head was instrumented with an array of tri-axial accelerometers mounted at the head centre of gravity. Differences in RLA between the roundhouse kick (130.11±51.67 g) and hook punch (71.23±32.19 g, d = 1.39) and in HIC15 (clench axe kick: 162.63±104.10; uppercut: 24.10±12.54, d = 2.29) were observed. Taekwondo kicks demonstrated significantly larger magnitudes than boxing punches for both RLA and HIC.

The structure and evolution of galacto-detonation waves - Some analytic results in sequential star formation models of spiral galaxies

NASA Technical Reports Server (NTRS)

Cowie, L. L.; Rybicki, G. B.

1982-01-01

Waves of star formation in a uniform, differentially rotating disk galaxy are treated analytically as a propagating detonation wave front. It is shown, that if single solitary waves could be excited, they would evolve asymptotically to one of two stable spiral forms, each of which rotates with a fixed pattern speed. Simple numerical solutions confirm these results. However, the pattern of waves that develop naturally from an initially localized disturbance is more complex and dies out within a few rotation periods. These results suggest a conclusive observational test for deciding whether sequential star formation is an important determinant of spiral structure in some class of galaxies.

Design/cost tradeoff studies. Appendix A. Supporting analyses and tradeoffs, book 2. Earth Observatory Satellite system definition study (EOS)

NASA Technical Reports Server (NTRS)

1974-01-01

Attitude reference systems for use with the Earth Observatory Satellite (EOS) are described. The systems considered are fixed and gimbaled star trackers, star mappers, and digital sun sensors. Covariance analyses were performed to determine performance for the most promising candidate in low altitude and synchronous orbits. The performance of attitude estimators that employ gyroscopes which are periodically updated by a star sensor is established by a single axis covariance analysis. The other systems considered are: (1) the propulsion system design, (2) electric power and electrical integration, (3) thermal control, (4) ground data processing, and (5) the test plan and cost reduction aspects of observatory integration and test.

Density Functional Calculations for the Neutron Star Matter at Subnormal Density

NASA Astrophysics Data System (ADS)

Kashiwaba, Yu; Nakatsukasa, Takashi

The pasta phases of nuclear matter, whose existence is suggested at low density, may influence observable properties of neutron stars. In order to investigate properties of the neutron star matter, we calculate self-consistent solutions for the ground states of slab-like phase using the microscopic density functional theory with Bloch wave functions. The calculations are performed at each point of fixed average density and proton fraction (\\bar{ρ },Yp), varying the lattice constant of the unit cell. For small Yp values, the dripped neutrons emerge in the ground state, while the protons constitute the slab (crystallized) structure. The shell effect of protons affects the thickness of the slab nuclei.

Nuclear ``pasta'' structures in low-density nuclear matter and properties of the neutron-star crust

NASA Astrophysics Data System (ADS)

Okamoto, Minoru; Maruyama, Toshiki; Yabana, Kazuhiro; Tatsumi, Toshitaka

2013-08-01

In the neutron-star crust, nonuniform structure of nuclear matter—called the “pasta” structure—is expected. From recent studies of giant flares in magnetars, these structures might be related to some observables and physical quantities of the neutron-star crust. To investigate the above quantities, we numerically explore the pasta structure with a fully three-dimensional geometry and study the properties of low-density nuclear matter, based on the relativistic mean-field model and the Thomas-Fermi approximation. We observe typical pasta structures for fixed proton number fraction and two of them for cold catalyzed matter. We also discuss the crystalline configuration of “pasta.”

Early-Type Galaxy Star Formation Histories in Different Environments

NASA Astrophysics Data System (ADS)

Fitzpatrick, Patrick; Graves, G.

2014-01-01

We use very high-S/N stacked spectra of ˜29,000 nearby quiescent early-type galaxies (ETGs) from the Sloan Digital Sky Survey (SDSS) to investigate variations in their star formation histories (SFHs) with environment at fixed position along and perpendicular to the Fundamental Plane (FP). We separate galaxies in the three-dimensional FP space defined by galaxy effective radius Re, central stellar velocity dispersion σ, and surface brightness residual from the FP, ΔIe. We use the SDSS group catalogue of Yang et al. to further separate galaxies into three categories by their “identities” within their respective dark matter halos: central “Brightest Group Galaxies” (BGGs); Satellites; and Isolateds (those which are “most massive” in a dark matter halo with no Satellites). Within each category, we construct high-S/N mean stacked spectra to determine mean singleburst ages, [Fe/H], and [Mg/Fe] based on the stellar population synthesis models of R. Schiavon. This allows us to study variations in the stellar population properties (SPPs) with local group environment at fixed structure (i.e., fixed position in FP-space). We find that the SFHs of quiescent ETGs are almost entirely determined by their structural parameters σ and ΔIe. Any variation with local group environment at fixed structure is only slight: Satellites have the oldest stellar populations, 0.02 dex older than BGGs and 0.04 dex older than Isolateds; BGGs have the highest Fe-enrichments, 0.01 dex higher than Isolateds and 0.02 dex higher than Satellites; there are no differences in Mg-enhancement between BGGs, Isolateds, and Satellites. Our observation that, to zeroth-order, the SFHs of quiescent ETGs are fully captured by their structures places important qualitative constraints on the degree to which late-time evolutionary processes (those which occur after a galaxy’s initial formation and main star-forming lifetime) can alter their SFHs/structures.

Emergence of postural patterns as a function of vision and translation frequency

NASA Technical Reports Server (NTRS)

Buchanan, J. J.; Horak, F. B.; Peterson, B. W. (Principal Investigator)

1999-01-01

Emergence of postural patterns as a function of vision and translation frequency. We examined the frequency characteristics of human postural coordination and the role of visual information in this coordination. Eight healthy adults maintained balance in stance during sinusoidal support surface translations (12 cm peak to peak) in the anterior-posterior direction at six different frequencies. Changes in kinematic and dynamic measures revealed that both sensory and biomechanical constraints limit postural coordination patterns as a function of translation frequency. At slow frequencies (0.1 and 0.25 Hz), subjects ride the platform (with the eyes open or closed). For fast frequencies (1.0 and 1.25 Hz) with the eyes open, subjects fix their head and upper trunk in space. With the eyes closed, large-amplitude, slow-sway motion of the head and trunk occurred for fast frequencies above 0.5 Hz. Visual information stabilized posture by reducing the variability of the head's position in space and the position of the center of mass (CoM) within the support surface defined by the feet for all but the slowest translation frequencies. When subjects rode the platform, there was little oscillatory joint motion, with muscle activity limited mostly to the ankles. To support the head fixed in space and slow-sway postural patterns, subjects produced stable interjoint hip and ankle joint coordination patterns. This increase in joint motion of the lower body dissipated the energy input by fast translation frequencies and facilitated the control of upper body motion. CoM amplitude decreased with increasing translation frequency, whereas the center of pressure amplitude increased with increasing translation frequency. Our results suggest that visual information was important to maintaining a fixed position of the head and trunk in space, whereas proprioceptive information was sufficient to produce stable coordinative patterns between the support surface and legs. The CNS organizes postural patterns in this balance task as a function of available sensory information, biomechanical constraints, and translation frequency.

Intrapartum sonographic imaging of fetal head asynclitism.

PubMed

Ghi, T; Youssef, A; Pilu, G; Malvasi, A; Ragusa, A

2012-02-01

Anterior asynclitism was suspected on digital examination of a laboring woman with late arrest of dilatation and no evidence of fetal head progression. Clinical examination revealed a fixed non-engaged fetal head (station −1), with a transverse posterior sagittal suture. A static three-dimensional volume was obtained by translabial ultrasound, offline analysis of which confirmed the clinical diagnosis of anterior asynclitism. Owing to the posterior twisting of the head towards the sacrum, the midline echo could only be obtained by cutting the volume with an oblique line, the direction of which was not perpendicular to the pubis as expected in cases of synclitic head. The sonographic appearance of the midline echo approaching the sacrum in a non-engaged transverse fetal head strongly supports the clinical suspicion of anterior asynclitism. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.

Steam separator latch assembly

DOEpatents

Challberg, Roy C.; Kobsa, Irvin R.

1994-01-01

A latch assembly removably joins a steam separator assembly to a support flange disposed at a top end of a tubular shroud in a nuclear reactor pressure vessel. The assembly includes an annular head having a central portion for supporting the steam separator assembly thereon, and an annular head flange extending around a perimeter thereof for supporting the head to the support flange. A plurality of latches are circumferentially spaced apart around the head flange with each latch having a top end, a latch hook at a bottom end thereof, and a pivot support disposed at an intermediate portion therebetween and pivotally joined to the head flange. The latches are pivoted about the pivot supports for selectively engaging and disengaging the latch hooks with the support flange for fixedly joining the head to the shroud or for allowing removal thereof.

Steam separator latch assembly

DOEpatents

Challberg, R.C.; Kobsa, I.R.

1994-02-01

A latch assembly removably joins a steam separator assembly to a support flange disposed at a top end of a tubular shroud in a nuclear reactor pressure vessel. The assembly includes an annular head having a central portion for supporting the steam separator assembly thereon, and an annular head flange extending around a perimeter thereof for supporting the head to the support flange. A plurality of latches are circumferentially spaced apart around the head flange with each latch having a top end, a latch hook at a bottom end thereof, and a pivot support disposed at an intermediate portion therebetween and pivotally joined to the head flange. The latches are pivoted about the pivot supports for selectively engaging and disengaging the latch hooks with the support flange for fixedly joining the head to the shroud or for allowing removal thereof. 12 figures.

Accurate Visual Heading Estimation at High Rotation Rate Without Oculomotor or Static-Depth Cues

NASA Technical Reports Server (NTRS)

Stone, Leland S.; Perrone, John A.; Null, Cynthia H. (Technical Monitor)

1995-01-01

It has been claimed that either oculomotor or static depth cues provide the signals about self-rotation necessary approx.-1 deg/s. We tested this hypothesis by simulating self-motion along a curved path with the eyes fixed in the head (plus or minus 16 deg/s of rotation). Curvilinear motion offers two advantages: 1) heading remains constant in retinotopic coordinates, and 2) there is no visual-oculomotor conflict (both actual and simulated eye position remain stationary). We simulated 400 ms of rotation combined with 16 m/s of translation at fixed angles with respect to gaze towards two vertical planes of random dots initially 12 and 24 m away, with a field of view of 45 degrees. Four subjects were asked to fixate a central cross and to respond whether they were translating to the left or right of straight-ahead gaze. From the psychometric curves, heading bias (mean) and precision (semi-interquartile) were derived. The mean bias over 2-5 runs was 3.0, 4.0, -2.0, -0.4 deg for the first author and three naive subjects, respectively (positive indicating towards the rotation direction). The mean precision was 2.0, 1.9, 3.1, 1.6 deg. respectively. The ability of observers to make relatively accurate and precise heading judgments, despite the large rotational flow component, refutes the view that extra-flow-field information is necessary for human visual heading estimation at high rotation rates. Our results support models that process combined translational/rotational flow to estimate heading, but should not be construed to suggest that other cues do not play an important role when they are available to the observer.

PHOTOEVAPORATING PROPLYD-LIKE OBJECTS IN CYGNUS OB2

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

Wright, Nicholas J.; Drake, Jeremy J.; Guarcello, Mario G.

2012-02-20

We report the discovery of 10 proplyd-like objects in the vicinity of the massive OB association Cygnus OB2. They were discovered in IPHAS H{alpha} images and are clearly resolved in broadband Hubble Space Telescope/Advanced Camera for Surveys, near-IR, and Spitzer mid-IR images. All exhibit the familiar tadpole shape seen in photoevaporating objects such as the Orion proplyds, with a bright ionization front at the head facing the central cluster of massive stars and a tail stretching in the opposite direction. Many also show secondary ionization fronts, complex tail morphologies, or multiple heads. We consider the evidence that these are eithermore » proplyds or 'evaporating gaseous globules' (EGGs) left over from a fragmenting molecular cloud, but find that neither scenario fully explains the observations. Typical sizes are 50,000-100,000 AU, larger than the Orion proplyds, but in agreement with the theoretical scaling of proplyd size with distance from the ionizing source. These objects are located at projected separations of {approx}6-14 pc from the OB association, compared to {approx}0.1 pc for the Orion proplyds, but are clearly being photoionized by the {approx}65 O-type stars in Cyg OB2. Central star candidates are identified in near- and mid-IR images, supporting the proplyd scenario, though their large sizes and notable asymmetries are more consistent with the EGG scenario. A third possibility is therefore considered that these are a unique class of photoevaporating partially embedded young stellar objects that have survived the destruction of their natal molecular cloud. This has implications for the properties of stars that form in the vicinity of massive stars.« less

Comparison of bilateral whisker movement in freely exploring and head-fixed adult rats.

PubMed

Sellien, Heike; Eshenroder, Donna S; Ebner, Ford F

2005-09-01

Rats move their whiskers actively during tactile exploration of their environment. The whiskers emanate from densely innervated whisker follicles that are moved individually by intrinsic facial muscles and as a group by extrinsic muscles. Several descriptions of whisker movements in normal adult rats during unrestrained exploration indicate that rats move their whiskers in the 6-9 Hz range when exploring a new environment. The rate can be elevated to nearly 20 Hz for brief episodes just prior to making a behavioural decision. The present studies were undertaken to compare whisker dynamics in head-restrained and freely moving rats with symmetrical or asymmetrical numbers of whiskers on the two sides of their face and to provide a description of differences in whisker use in exploring rats after trimming all but two whiskers on one side of the face, a condition that has been shown to induce robust cortical plasticity. Head-fixed rats were trained to protract their whiskers against a contact detector with sufficient force to trigger a chocolate milk reward. Whisker movements were analyzed, and the results from head-fixed animals were compared with free-running animals using trials taken during their initial exploration of novel objects that blocked the rat's progress down an elevated runway. The results show that symmetrical whisker movements are modulated both by the nature of the task and the number of whiskers available for exploration. Rats can change their whisker movements when the sensitivity (threshold) of a contact detector is raised or lowered, or when the nature of the task requires bilateral input from the whiskers. We show that trimming some, but not all whiskers on one side of the face modifies the synchrony of whisker movement compared to untrimmed or symmetrically trimmed whiskers.

See-What-I-Do: Increasing Mentor and Trainee Sense of Co-Presence in Trauma Surgeries with the STAR Platform

DTIC Science & Technology

2016-04-01

publications, images, and videos.  Technologies or techniques . The technique for one shot gesture recognition is a result from the research activity... shot learning concept for gesture recognition. Name: Aditya Ajay Shanghavi Project Role: Master Student Researcher Identifier (e.g. ORCID ID...use case . The transparency error depends more on the x than the z head tracking error. Head tracking is typically accurate to less than 10mm in x

Modulation of head movement control in humans during treadmill walking

NASA Technical Reports Server (NTRS)

Mulavara, Ajitkumar P.; Verstraete, Mary C.; Bloomberg, Jacob J.

2002-01-01

The purpose of this study was to investigate the coordination of the head relative to the trunk within a gait cycle during gaze fixation. Nine normal subjects walked on a motorized treadmill driven at 1.79 m/s (20 s trials) while fixing their gaze on a centrally located earth-fixed target positioned at a distance of 2 m from their eyes. The net and relative angular motions of the head about the three axes of rotations, as well as the corresponding values for the moments acting on it relative to the trunk during the gait cycle were quantified and used as measures of coordination. The average net moment, as well as the average moments about the different axes were significantly different (P<0.01) between the high impact and low/no impact phases of the gait cycle. However, the average net angular displacement as well as the average angular displacement about the axial rotation axis of the head relative to the trunk was maintained uniform (P>0.01) throughout the gait cycle. The average angular displacement about the lateral bending axis was significantly increased (P<0.01) during the high impact phase while that about the flexion-extension axis was significantly decreased (P<0.01) throughout the gait cycle. Thus, the coordination of the motion of the head relative to the trunk during walking is dynamically modulated depending on the behavioral events occurring in the gait cycle. This modulation may serve to aid stabilization of the head by counteracting the force variations acting on the upper body that may aid in the visual fixation of targets during walking.

Rapid motor learning in the translational vestibulo-ocular reflex

NASA Technical Reports Server (NTRS)

Zhou, Wu; Weldon, Patrick; Tang, Bingfeng; King, W. M.; Shelhamer, M. J. (Principal Investigator)

2003-01-01

Motor learning was induced in the translational vestibulo-ocular reflex (TVOR) when monkeys were repeatedly subjected to a brief (0.5 sec) head translation while they tried to maintain binocular fixation on a visual target for juice rewards. If the target was world-fixed, the initial eye speed of the TVOR gradually increased; if the target was head-fixed, the initial eye speed of the TVOR gradually decreased. The rate of learning acquisition was very rapid, with a time constant of approximately 100 trials, which was equivalent to <1 min of accumulated stimulation. These learned changes were consolidated over >or=1 d without any reinforcement, indicating induction of long-term synaptic plasticity. Although the learning generalized to targets with different viewing distances and to head translations with different accelerations, it was highly specific for the particular combination of head motion and evoked eye movement associated with the training. For example, it was specific to the modality of the stimulus (translation vs rotation) and the direction of the evoked eye movement in the training. Furthermore, when one eye was aligned with the heading direction so that it remained motionless during training, learning was not expressed in this eye, but only in the other nonaligned eye. These specificities show that the learning sites are neither in the sensory nor the motor limb of the reflex but in the sensory-motor transformation stage of the reflex. The dependence of the learning on both head motion and evoked eye movement suggests that Hebbian learning may be one of the underlying cellular mechanisms.

Metal-Poor, Strongly Star-Forming Galaxies in the DEEP2 Survey: The Relationship Between Stellar Mass, Temperature-Based Metallicity, and Star Formation Rate

NASA Technical Reports Server (NTRS)

Ly, Chun; Rigby, Jane R.; Cooper, Michael; Yan, Renbin

2015-01-01

We report on the discovery of 28 redshift (z) approximately 0.8 metal-poor galaxies in DEEP2. These galaxies were selected for their detection of the weak [O (sub III)] lambda 4363 emission line, which provides a "direct" measure of the gas-phase metallicity. A primary goal for identifying these rare galaxies is to examine whether the fundamental metallicity relation (FMR) between stellar mass, gas metallicity, and star formation rate (SFR) extends to low stellar mass and high SFR. The FMR suggests that higher SFR galaxies have lower metallicity (at fixed stellar mass). To test this trend, we combine spectroscopic measurements of metallicity and dust-corrected SFRs, with stellar mass estimates from modeling the optical photometry. We find that these galaxies are 1.05 plus or minus 0.61 decimal exponent (dex) above the redshift (z) approximately equal to 1 stellar mass-SFR relation, and 0.23 plus or minus 0.23 decimal exponent (dex) below the local mass-metallicity relation. Relative to the FMR, the latter offset is reduced to 0.01 decimal exponent (dex), but significant dispersion remains (0.29 decimal exponent (dex) with 0.16 decimal exponent (dex) due to measurement uncertainties). This dispersion suggests that gas accretion, star formation and chemical enrichment have not reached equilibrium in these galaxies. This is evident by their short stellar mass doubling timescale of approximately 100 (sup plus 310) (sub minus 75) million years that suggests stochastic star formation. Combining our sample with other redshift (z) of approximately 1 metal-poor galaxies, we find a weak positive SFR-metallicity dependence (at fixed stellar mass) that is significant at 97.3 percent confidence. We interpret this positive correlation as recent star formation that has enriched the gas, but has not had time to drive the metal-enriched gas out with feedback mechanisms.

Metal-Poor, Strongly Star-Forming Galaxies in the DEEP2 Survey: The Relationship Between Stellar Mass, Temperature-Based Metallicity, and Star Formation Rate

NASA Technical Reports Server (NTRS)

Ly, Chun; Rigby, Jane R.; Cooper, Michael; Yan, Renbin

2015-01-01

We report on the discovery of 28 redshift (z) approximately equal to 0.8 metal-poor galaxies in DEEP2. These galaxies were selected for their detection of the weak [O (sub III)] lambda 4363 emission line, which provides a "direct" measure of the gas-phase metallicity. A primary goal for identifying these rare galaxies is to examine whether the fundamental metallicity relation (FMR) between stellar mass, gas metallicity, and star formation rate (SFR) holds for low stellar mass and high SFR galaxies. The FMR suggests that higher SFR galaxies have lower metallicity (at fixed stellar mass). To test this trend, we combine spectroscopic measurements of metallicity and dust-corrected SFR with stellar mass estimates from modeling the optical photometry. We find that these galaxies are 1.05 plus or minus 0.61 dex above the redshift (z) approximately 1 stellar mass-SFR relation and 0.23 plus or minus 0.23 dex below the local mass-metallicity relation. Relative to the FMR, the latter offset is reduced to 0.01 dex, but significant dispersion remains dex with 0.16 dex due to measurement uncertainties). This dispersion suggests that gas accretion, star formation, and chemical enrichment have not reached equilibrium in these galaxies. This is evident by their short stellar mass doubling timescale of approximately equal to 100 (sup plus 310) (sub minus 75) million years which suggests stochastic star formation. Combining our sample with other redshift (z) of approximately 1 metal-poor galaxies, we find a weak positive SFR-metallicity dependence (at fixed stellar mass) that is significant at 94.4 percent confidence. We interpret this positive correlation as recent star formation that has enriched the gas but has not had time to drive the metal-enriched gas out with feedback mechanisms.

Star-dust geometries in galaxies: The effect of interstellar matter distributions on optical and infrared properties of late-type galaxies

NASA Technical Reports Server (NTRS)

Capuano, J. M., Jr.; Thronson, H. A., Jr.; Witt, A. N.

1993-01-01

The presence of substantial amounts of interstellar dust in late-type galaxies affects observable parameters such as the optical surface brightness, the color, and the ratio of far-infrared to optical luminosity of these galaxies. We conducted radiative transfer calculations for late-type galaxy environments to examine two different scenarios: (1) the effects of increasing amounts of dust in two fixed geometries with different star distributions; and (2) the effects of an evolving dust-star geometry in which the total amount of dust is held constant, for three different star distributions. The calculations were done for ten photometric bands, ranging from the far-ultraviolet to the near-infrared (K), and scattered light was included in the galactic surface brightness at each wavelength. The energy absorbed throughout these ten photometric bands was assumed to re-emerge in the far-infrared as thermal dust emission. We also considered the evolutionary contraction of a constant amount of dust relative to pre-existing star distributions.

Seeing Beyond the Monkey Head

NASA Image and Video Library

2015-08-20

Scores of baby stars shrouded by dust are revealed in this infrared image of the star-forming region NGC 2174, as seen by NASA Spitzer Space Telescope. Found in the constellation Orion, NGC 2174 is located around 6,400 light-years away. Some of the clouds in the region resemble the face of a monkey in visible-light images, hence the nebula's nickname: the "Monkey Head." However, in infrared images such as this, the monkey disappears. That's because different clouds are highlighted in infrared and visible-light images. Found in the northern reaches of the constellation Orion, NGC 2174 is located around 6,400 light-years away. Columns of dust, slightly to the right of center in the image, are being carved out of the dust by radiation and stellar winds from the hottest young stars recently born in the area. Spitzer's infrared view provides us with a preview of the next clusters of stars that will be born in the coming millennia. The reddish spots of light scattered through the darker filaments are infant stars swaddled by blankets of warm dust. The warm dust glows brightly at infrared wavelengths. Eventually, these stars will pop out of their dusty envelopes and their light will carve away at the dust clouds surrounding them. In this image, infrared wavelengths have been assigned visible colors we see with our eyes. Light with a wavelength of 3.5 microns is shown in blue, 8.0 microns is green, and 24 microns in red. The greens show the organic molecules in the dust clouds, illuminated by starlight. Reds are caused by the thermal radiation emitted from the very hottest areas of dust. Areas around the edges that were not observed by Spitzer have been filled in using infrared observations from NASA's Wide Field Infrared Survey Explorer, or WISE. http://photojournal.jpl.nasa.gov/catalog/PIA19836

Wonderful Mira.

PubMed

Wareing, Christopher John

2008-12-13

Since being named 'wonderful' in the seventeenth century for its peculiar brightness variability, Mira A has been the subject of extensive research and become the prototype for a whole class of 'Mira' variable stars. The primary star in a binary system, Mira A is reaching the end of its life and currently undergoing an extended period of enhanced mass loss. Recent observations have revealed a surrounding arc-like structure and a stream of material stretching 12 light years away in opposition to the arc. In this article, I review recent modelling of this cometary appearance as a bow shock with an accompanying tail of material ram pressure stripped from the head of the bow shock, place Mira in an evolutionary context, predict its future with reference to the similar star R Hya and planetary nebula Sh 2-188, and speculate some avenues of research both on Mira itself and on other 'Mira-like' stars with bow shocks and tails. I also discuss the implications of this discovery for our own star, the Sun.

MONET, HET and SALT and asteroseismological observations and theory in Göttingen

NASA Astrophysics Data System (ADS)

Schuh, S.; Hessman, F. V.; Dreizler, S.; Kollatschny, W.; Glatzel, W.

2007-06-01

The Göttingen stellar astrophysics group, headed by Stefan Dreizler, conducts research on extrasolar planets and their host stars, on lower-main sequence stars, and on evolved compact objects, in particular hot white dwarfs (including PG 1159 objects, magnetic WDs and cataclysmic variables), and subdwarf B stars. In addition to sophisticated NLTE spectral analyses of these stars, which draw on the extensive stellar atmosphere modelling experience of the group, we actively develop and apply a variety of photometric monitoring and time-resolved spectroscopic techniques to address time-dependent phenomena. With the new instrumentational developments described below, we plan to continue the study of variable white dwarfs (GW Vir, DB and ZZ Ceti variables) and in particular sdB EC 14026 and PG 1617 pulsators which already constitute a main focus, partly within the Whole Earth Telescope (WET/DARC), http://www.physics.udel.edu/~jlp/darc/) collaboration, on a new level. Additional interest is directed towards strange mode instabilities in Wolf Rayet stars.

Role of age and injury mechanism on cervical spine injury tolerance from head contact loading.

PubMed

Yoganandan, Narayan; Chirvi, Sajal; Voo, Liming; Pintar, Frank A; Banerjee, Anjishnu

2018-02-17

The objective of this study was to determine the influence of age and injury mechanism on cervical spine tolerance to injury from head contact loading using survival analysis. This study analyzed data from previously conducted experiments using post mortem human subjects (PMHS). Group A tests used the upright intact head-cervical column experimental model. The inferior end of the specimen was fixed, the head was balanced by a mechanical system, and natural lordosis was removed. Specimens were placed on a testing device via a load cell. The piston applied loading at the vertex region. Spinal injuries were identified using medical images. Group B tests used the inverted head-cervical column experimental model. In one study, head-T1 specimens were fixed distally, and C7-T1 joints were oriented anteriorly, preserving lordosis. Torso mass of 16 kg was added to the specimen. In another inverted head-cervical column study, occiput-T2 columns were obtained, an artificial head was attached, T1-T2 was fixed, C4-C5 disc was maintained horizontal in the lordosis posture, and C7-T1 was unconstrained. The specimens were attached to the drop test carriage carrying a torso mass of 15 kg. A load cell at the inferior end measured neck loads in both studies. Axial neck force and age were used as the primary response variable and covariate to derive injury probability curves using survival analysis. Group A tests showed that age is a significant (P < .05) and negative covariate; that is, increasing age resulted in decreasing force for the same risk. Injuries were mainly vertebral body fractures and concentrated at one level, mid-to-lower cervical spine, and were attributed to compression-related mechanisms. However, age was not a significant covariate for the combined data from group B tests. Both group B tests produced many soft tissue injuries, at all levels, from C1 to T1. The injury mechanism was attributed to mainly extension. Multiple and noncontiguous injuries occurred. Injury probability curves, ±95% confidence intervals, and normalized confidence interval sizes representing the quality of the mean curve are given for different data sets. For compression-related injuries, specimen age should be used as a covariate or individual specimen data may be prescaled to derive risk curves. For distraction- or extension-related injuries, however, specimen age need not be used as a covariate in the statistical analysis. The findings from these tests and survival analysis indicate that the age factor modulates human cervical spine tolerance to impact injury.

Reversal of diuretic-associated impaired glucose tolerance and new-onset diabetes: results of the STAR-LET study.

PubMed

Bakris, George; Molitch, Mark; Zhou, Qian; Sarafidis, Pantelis; Champion, Annette; Bacher, Peter; Sowers, James R

2008-01-01

Reversal of new-onset diabetes secondary to thiazide diuretic use remains questionable. STAR-LET was a 6-month extension of the Study of Trandolapril/Verapamil SR and Insulin Resistance (STAR), which assessed the effects of a fixed-dose renin-angiotensin system inhibitor (RASI)/hydrochlorothiazide (HCTZ) combination on changes in 2-hour oral glucose tolerance test (OGTT) results. STAR-LET explored whether the glycemic impact of HCTZ could be reversed by conversion to a RASI/verapamil combination. The primary outcome was change in 2-hour OGTT results. Fifty-one percent of the STAR patients were enrolled in STAR-LET. The 2-hour OGTT value (mmol/L) was unchanged from STAR baseline in the RASI/verapamil group (7.7+/-2.4 vs 8.1+/-3.3; P=.18) and improved in those who were switched from RASI/HCTZ to RASI/verapamil (8.5+/-3.0 vs 7.2+/-2.3; P<.001). This exploratory study suggests that the impairment in glycemic control seen with use of a thiazide diuretic combined with a RASI can be reversed by switching to a regimen that does not include a diuretic.

Current status of the laser guide star adaptive optics system for Subaru Telescope

NASA Astrophysics Data System (ADS)

Hayano, Yutaka; Takami, Hideki; Guyon, Olivier; Oya, Shin; Hattori, Masayuki; Saito, Yoshihiko; Watanabe, Makoto; Murakami, Naoshi; Minowa, Yosuke; Ito, Meguru; Colley, Stephen; Eldred, Michael; Golota, Taras; Dinkins, Matthew; Kashikawa, Nobunari; Iye, Masanori

2008-07-01

The current status and recent results, since last SPIE conference at Orlando in 2006, for the laser guide star adaptive optics system for Subaru Telescope is presented. We had a first light using natural guide star and succeed to launch the sodium laser beam in October 2006. The achieved Strehl ratio on the 10th magnitude star was around 0.5 at K band. We confirmed that the full-width-half-maximum of the stellar point spread function is smaller than 0.1 arcsec even at the 0.9 micrometer wavelehgth. The size of the artificial guide star by the laser beam tuned at the wavelength of 589 nm was estimated to be 10 arcsec. The obtained blurred artificial guide star is caused by the wavefront error on the laser launching telescope. After the first light and first launch, we found that we need to modify and to fix the components, which are temporarily finished. Also components, which were postponed to fabricate after the first light, are required to build newly. All components used by the natural guide star adaptive optics system are finalized recently and we are ready to go on the sky. Next engineering observation is scheduled in August, 2008.

A view of the H-band light-element chemical patterns in globular clusters under the AGB self-enrichment scenario

NASA Astrophysics Data System (ADS)

Dell'Agli, F.; García-Hernández, D. A.; Ventura, P.; Mészáros, Sz; Masseron, T.; Fernández-Trincado, J. G.; Tang, B.; Shetrone, M.; Zamora, O.; Lucatello, S.

2018-04-01

We discuss the self-enrichment scenario by asymptotic giant branch (AGB) stars for the formation of multiple populations in globular clusters (GCs) by analysing data set of giant stars observed in nine Galactic GCs, covering a wide range of metallicities and for which the simultaneous measurements of C, N, O, Mg, Al, and Si are available. To this aim, we calculated six sets of AGB models, with the same chemical composition as the stars belonging to the first generation of each GC. We find that the AGB yields can reproduce the set of observations available, not only in terms of the degree of contamination shown by stars in each GC but, more important, also the observed trend with metallicity, which agrees well with the predictions from AGB evolution modelling. While further observational evidences are required to definitively fix the main actors in the pollution of the interstellar medium from which new generation of stars formed in GCs, the present results confirm that the gas ejected by stars of mass in the range 4 M_{⊙} ≤ M ≤ 8 M_{⊙} during the AGB phase share the same chemical patterns traced by stars in GCs.

ScienceCast 64: Andromeda vs. the Milky Way: Astronomers Predict a Titanic Collision

NASA Image and Video Library

2012-06-08

Astronomers no longer have any doubt: Our Milky Way Galaxy will have a head-on collision with Andromeda. Fortunately, they say, Earth will survive when the two great star systems meet 4 billions years from now.

Early type galaxies: Mapping out the two-dimensional space of galaxy star formation histories

NASA Astrophysics Data System (ADS)

Graves, Genevieve J.

Early type galaxies form a multi-parameter family, as evidenced by the two- dimensional (2-D) Fundamental Plane relationship. However, their star formation histories are often treated as a one-dimensional mass sequence. This dissertation presents a systematic study of the relationship between the multi- parameter structural properties of early type galaxies and their star formation histoires. We demonstrate that the stellar populations of early type galaxies span a 2-D space, which means that their star formation histories form a two- parameter family. This 2-D family is then mapped onto several familiar early type galaxy scaling relations, including the color-magnitude relation, the Fundamental Plane, and a cross-section through the Fundamental Plane. We find that the stellar population properties, and therefore the star formation histories of early type galaxies depend most strongly on galaxy velocity dispersion (s), rather than on luminosity ( L ), stellar mass ( M [low *] ), or dynamical mass ( M dyn ). Interestingly, stellar populations are independent of the radius ( R e ) of the galaxies. At fixed s, they show correlated residuals through the thickness of the Fundamental Plane (FP) in the surface-brightness ( I e ) dimension, such that low-surface-brightness galaxies are older, less metal-enriched, and more enhanced in Mg relative to Fe than their counterparts at the same s and R e on the FP midplane. Similarly, high- surface-brightness galaxies are younger, more metal-rich, and less Mg-enhanced than their counterparts on the FP midplane. These differences suggest that the duration of star formation varies through the thickness of the FP. If the dynamical mass-to-light ratios of early type galaxies ( M dyn /L ) were constant for all such galaxies, the FP would be equivalent to the plane predicted by the virial relation. However, the observed FP does not exactly match the virial plane. The FP is tilted from the virial plane, indicating that M dyn /L varies systematically across it. Furthermore the FP relation, although relatively tight, shows more scatter in surface brightness (at fixed s and R e ) than is predicted by observational errors. This finite thickness indicates that M dyn /L also varies at a fixed point on the FP. We observe that the stellar populations of early type galaxies vary through the thickness of the FP. These differences translate into variations in the stellar mass-to-light ratio ( M [low *] /L ) that contribute to both the tilt and the thickness of the FP. However, the mass-to-light variations due to stellar population differences are too small to explain either the tilt of the FP or its thickness. This implies that the tilt and thickness of the FP are driven by systematic variations in either the central dark matter fraction in galaxies or in the IMF with which they form stars. Furthermore, because star formation histories can be mapped onto locations in FP-space, the variations in central dark matter fraction or IMF differences must be correlated with differences in the galaxies' star formation histories.

Alternative display and interaction devices

NASA Technical Reports Server (NTRS)

Bolas, M. T.; McDowall, I. E.; Mead, R. X.; Lorimer, E. R.; Hackbush, J. E.; Greuel, C.

1995-01-01

While virtual environment systems are typically thought to consist of a head mounted display and a flex-sensing glove, alternative peripheral devices are beginning to be developed in response to application requirements. Three such alternatives are discussed: fingertip sensing gloves, fixed stereoscopic viewers, and counterbalanced head mounted displays. A subset of commercial examples that highlight each alternative is presented as well as a brief discussion of interesting engineering and implementation issues.

STAR FORMATION AT 4 < z < 6 FROM THE SPITZER LARGE AREA SURVEY WITH HYPER-SUPRIME-CAM (SPLASH)

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

Steinhardt, Charles L.; Capak, Peter; Masters, Dan

2014-08-20

Using the first 50% of data collected for the Spitzer Large Area Survey with Hyper-Suprime-Cam observations on the 1.8 deg{sup 2} Cosmological Evolution Survey we estimate the masses and star formation rates of 3398 M {sub *} > 10{sup 10} M {sub ☉} star-forming galaxies at 4 < z < 6 with a substantial population up to M {sub *} ≳ 10{sup 11.5} M {sub ☉}. We find that the strong correlation between stellar mass and star formation rate seen at lower redshift (the ''main sequence'' of star-forming galaxies) extends to z ∼ 6. The observed relation and scatter is consistentmore » with a continued increase in star formation rate at fixed mass in line with extrapolations from lower-redshift observations. It is difficult to explain this continued correlation, especially for the most massive systems, unless the most massive galaxies are forming stars near their Eddington-limited rate from their first collapse. Furthermore, we find no evidence for moderate quenching at higher masses, indicating quenching either has not occurred prior to z ∼ 6 or else occurs rapidly, so that few galaxies are visible in transition between star-forming and quenched.« less

Cat got your tongue? Using the tip-of-the-tongue state to investigate fixed expressions.

PubMed

Nordmann, Emily; Cleland, Alexandra A; Bull, Rebecca

2013-01-01

Despite the fact that they play a prominent role in everyday speech, the representation and processing of fixed expressions during language production is poorly understood. Here, we report a study investigating the processes underlying fixed expression production. "Tip-of-the-tongue" (TOT) states were elicited for well-known idioms (e.g., hit the nail on the head) and participants were asked to report any information they could regarding the content of the phrase. Participants were able to correctly report individual words for idioms that they could not produce. In addition, participants produced both figurative (e.g., pretty for easy on the eye) and literal errors (e.g., hammer for hit the nail on the head) when in a TOT state, suggesting that both figurative and literal meanings are active during production. There was no effect of semantic decomposability on overall TOT incidence; however, participants recalled a greater proportion of words for decomposable rather than non-decomposable idioms. This finding suggests there may be differences in how decomposable and non-decomposable idioms are retrieved during production. Copyright © 2013 Cognitive Science Society, Inc.

Spatial Orientation and Balance Control Changes Induced by Altered Gravito-Inertial Force Vectors in Vestibular Deficient Patients

NASA Technical Reports Server (NTRS)

Kaufman, Galen D.; Wood, Scott J.; Gianna, Claire C.; Black, F. Owen; Paloski, William H.

2000-01-01

Eight chronic vestibular deficient (VD) patients (bilateral N = 4, unilateral N = 4, ages 18-67 were exposed to an interaural centripetal acceleration of 1 G (resultant 45 degree roll tilt of 1.4 G) on a 0.8 meter radius centrifuge for up to 90 minutes in the dark. The patients sat with head fixed upright, except every 4 of 10 minutes when instructed to point their nose and eyes towards a visual target (switched on every 3 to 5 seconds at random places within plus or minus 30 deg) in the Earth horizontal plane. Eye movements, including directed saccades for subjective Earth-and head-referenced planes, were recorded before, during, and after centrifugation using electro-oculography. Postural sway was measured before and within ten minutes after centrifugation using a sway-referenced or earth-fixed support surface, and with or without a head movement sequence. The protocol was selected for each patient based on the most challenging condition in which the patient was able to maintain balance with eyes closed.

Perceived Surface Slant Is Systematically Biased in the Actively-Generated Optic Flow

PubMed Central

Fantoni, Carlo; Caudek, Corrado; Domini, Fulvio

2012-01-01

Humans make systematic errors in the 3D interpretation of the optic flow in both passive and active vision. These systematic distortions can be predicted by a biologically-inspired model which disregards self-motion information resulting from head movements (Caudek, Fantoni, & Domini 2011). Here, we tested two predictions of this model: (1) A plane that is stationary in an earth-fixed reference frame will be perceived as changing its slant if the movement of the observer's head causes a variation of the optic flow; (2) a surface that rotates in an earth-fixed reference frame will be perceived to be stationary, if the surface rotation is appropriately yoked to the head movement so as to generate a variation of the surface slant but not of the optic flow. Both predictions were corroborated by two experiments in which observers judged the perceived slant of a random-dot planar surface during egomotion. We found qualitatively similar biases for monocular and binocular viewing of the simulated surfaces, although, in principle, the simultaneous presence of disparity and motion cues allows for a veridical recovery of surface slant. PMID:22479473

Dark Globule in IC 1396 (IRAC)

NASA Technical Reports Server (NTRS)

2003-01-01

[figure removed for brevity, see original site] Click on image for larger view of inset

NASA's Spitzer Space Telescope image of a glowing stellar nursery provides a spectacular contrast to the opaque cloud seen in visible light (inset). The Elephant's Trunk Nebula is an elongated dark globule within the emission nebula IC 1396 in the constellation of Cepheus. Located at a distance of 2,450 light-years, the globule is a condensation of dense gas that is barely surviving the strong ionizing radiation from a nearby massive star. The globule is being compressed by the surrounding ionized gas. The dark globule is seen in silhouette at visible-light wavelengths, backlit by the illumination of a bright star located to the left of the field of view.

The Spitzer Space Telescope pierces through the obscuration to reveal the birth of new protostars, or embryonic stars, and previously unseen young stars. The infrared image was obtained by Spitzer's infrared array camera. The image is a four-color composite of invisible light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8.0 microns (red). The filamentary appearance of the globule results from the sculpting effects of competing physical processes. The winds from a massive star, located to the left of the image, produce a dense circular rim comprising the 'head' of the globule and a swept-back tail of gas.

A pair of young stars (LkHa 349 and LkHa 349c) that formed from the dense gas has cleared a spherical cavity within the globule head. While one of these stars is significantly fainter than the other in the visible-light image, they are of comparable brightness in the infrared Spitzer image. This implies the presence of a thick and dusty disc around LkHa 349c. Such circumstellar discs are the precursors of planetary systems. They are much thicker in the early stages of stellar formation when the placental planet-forming material (gas and dust) is still present.

Proton depth dose distribution: 3-D calculation of dose distributions from solar flare irradiation

NASA Astrophysics Data System (ADS)

Leavitt, Dennis D.

1990-11-01

Relative depth dose distribution to the head from 3 typical solar flare proton events were calculated for 3 different exposure geometries: (1) single directional radiation incident upon a fixed head; (2) single directional radiation incident upon head rotating axially (2-D rotation); and (3) omnidirectional radiation incident upon head (3-D rotation). Isodose distributions in the transverse plane intersecting isocenter are presented for each of the 3 solar flare events in all 3 exposure geometries. In all 3 calculation configurations the maximum predicted dose occurred on the surface of the head. The dose at the isocenter of the head relative to the surface dose for the 2-D and 3-D rotation geometries ranged from 2 to 19 percent, increasing with increasing energy of the event. The calculations suggest the superficially located organs (lens of the eye and skin) are at greatest risk for the proton events studied here.

Angular velocity integration in a fly heading circuit.

PubMed

Turner-Evans, Daniel; Wegener, Stephanie; Rouault, Hervé; Franconville, Romain; Wolff, Tanya; Seelig, Johannes D; Druckmann, Shaul; Jayaraman, Vivek

2017-05-22

Many animals maintain an internal representation of their heading as they move through their surroundings. Such a compass representation was recently discovered in a neural population in the Drosophila melanogaster central complex, a brain region implicated in spatial navigation. Here, we use two-photon calcium imaging and electrophysiology in head-fixed walking flies to identify a different neural population that conjunctively encodes heading and angular velocity, and is excited selectively by turns in either the clockwise or counterclockwise direction. We show how these mirror-symmetric turn responses combine with the neurons' connectivity to the compass neurons to create an elegant mechanism for updating the fly's heading representation when the animal turns in darkness. This mechanism, which employs recurrent loops with an angular shift, bears a resemblance to those proposed in theoretical models for rodent head direction cells. Our results provide a striking example of structure matching function for a broadly relevant computation.

Seeing Red in NGC 1978, NGC 55, and NGC 3109

NASA Astrophysics Data System (ADS)

Davidge, T. J.

2018-04-01

Spectra of the intermediate-age star cluster NGC 1978 and the dwarf irregular galaxies NGC 55 and NGC 3109 are discussed. The spectra were recorded with the Gemini Multi-object Spectrograph on Gemini South and span the 0.7–1.1 μm wavelength interval. Five slit pointings were observed in NGC 1978, and these are used to examine stochastic effects on the integrated red light from an intermediate-age cluster. The removal of either the brightest M giant or the brightest C star from the co-added spectrum has minor effects on the equivalent withs of the Ca triplet. The most robust signature of C stars in the integrated cluster spectrum at these wavelengths is the CN band head near 7900 Å. The equivalent widths of Ca triplet lines in the NGC 1978 spectrum and in the spectra of individual cluster stars are larger than expected for a scaled-solar abundance system. It is suggested that these stars have a lower than expected surface gravity, which might occur if the stars in NGC 1978 have been subject to extra mixing processes, as suggested by Lederer et al. The near-infrared color profile of NGC 1978 is shown to contain a prominent red cusp in the central 10 arcsec, and the suppression of light from this cusp does not affect the depth of the Ca lines in the integrated spectrum. The NGC 55 spectra run parallel to the major axis, and a gradient is found in the strength of the Ca lines, in the sense that the Ca lines weaken with increasing distance from the disk plane. Comparisons with models suggest that the disk light is dominated by stars with ages 1–2 Gyr, in agreement with star-forming histories (SFHs) obtained from the analysis of color–magnitude diagrams (CMDs). The NGC 55 spectra also sample a large star-forming complex. The age of this complex inferred from comparisons with models is broadly consistent with that estimated from a near-infrared CMD of the same region. The CN band head at 7900 Å in this part of NGC 55 is detected, but this is likely a signature of red supergiants (RSGs) rather than C stars. The NGC 3109 observations sample three different parts of that galaxy but have a low signal-to-noise ratio. Comparisons with models suggest that the light from the NGC 3109 disk at red wavelengths is dominated by RSGs with ages of at most a few tens of Myr, in qualitative agreement with SFHs that are based on photometric measurements.

Lepton-rich cold QCD matter in protoneutron stars

NASA Astrophysics Data System (ADS)

Jiménez, J. C.; Fraga, E. S.

2018-05-01

We investigate protoneutron star matter using the state-of-the-art perturbative equation of state for cold and dense QCD in the presence of a fixed lepton fraction in which both electrons and neutrinos are included. Besides computing the modifications in the equation of state due to the presence of trapped neutrinos, we show that stable strange quark matter has a more restricted parameter space. We also study the possibility of nucleation of unpaired quark matter in the core of protoneutron stars by matching the lepton-rich QCD pressure onto a hadronic equation of state, namely TM1 with trapped neutrinos. Using the inherent dependence of perturbative QCD on the renormalization scale parameter, we provide a measure of the uncertainty in the observables we compute.

Continuous prophylaxis with recombinant factor IX Fc fusion protein and conventional recombinant factor IX products: comparisons of efficacy and weekly factor consumption.

PubMed

Iorio, Alfonso; Krishnan, Sangeeta; Myrén, Karl-Johan; Lethagen, Stefan; McCormick, Nora; Yermakov, Sander; Karner, Paul

2017-04-01

Continuous prophylaxis for patients with hemophilia B requires frequent injections that are burdensome and that may lead to suboptimal adherence and outcomes. Hence, therapies requiring less-frequent injections are needed. In the absence of head-to-head comparisons, this study compared the first extended-half-life-recombinant factor IX (rFIX) product-recombinant factor IX Fc fusion protein (rFIXFc)-with conventional rFIX products based on annualized bleed rates (ABRs) and factor consumption reported in studies of continuous prophylaxis. This study compared ABRs and weekly factor consumption rates in clinical studies of continuous prophylaxis treatment with rFIXFc and conventional rFIX products (identified by systematic literature review) in previously-treated adolescents and adults with moderate-to-severe hemophilia B. Meta-analysis was used to pool ABRs reported for conventional rFIX products for comparison. Comparisons of weekly factor consumption were based on the mean, reported or estimated from the mean dose per injection. Five conventional rFIX studies (injections 1 to >3 times/week) met the criteria for comparison with once-weekly rFIXFc reported by the B-LONG study. The pooled mean ABR for conventional rFIX was slightly higher than but comparable to rFIXFc (difference=0.71; p = 0.210). Weekly factor consumption was significantly lower with rFIXFc than in conventional rFIX studies (difference in means = 42.8-74.5 IU/kg/week [93-161%], p < 0.001). Comparisons of clinical study results suggest weekly injections with rFIXFc result in similar bleeding rates and significantly lower weekly factor consumption compared with more-frequently-injected conventional rFIX products. The real-world effectiveness of rFIXFc may be higher based on results from a model of the impact of simulated differences in adherence.

Hybrid Aluminum and Natural Fiber Composite Structure for Crash Safety Improvement

NASA Astrophysics Data System (ADS)

Helaili, S.; Chafra, M.; Chevalier, Y.

There is a growing interest on pedestrian's protection in automotive safety standards. Pedestrians head impact is one of the most important tests. In this paper, a hybrid composite structure made from natural fiber and aluminum, which improve the head protection when impact is taken place, is presented. The structure is made from a honeycomb composite made from unidirectional and woven composites and a thin aluminum layer. A head impact model is developed. The number of hexagonal layers is fixed and the thickness of the aluminum layer of the honeycomb structure is varied. The specific absorption energy is then calculated.

Gender Discrimination in the Allocation of Migrant Household Resources.

PubMed

Antman, Francisca M

2015-07-01

This paper considers the relationship between international migration and gender discrimination through the lens of decision-making power over intrahousehold resource allocation. The endogeneity of migration is addressed with a difference-in-differences style identification strategy and a model with household fixed effects. The results suggest that while a migrant household head is away, a greater share of resources is spent on girls relative to boys and his spouse commands greater decision-making power. Once the head returns home, however, a greater share of resources goes to boys and there is suggestive evidence of greater authority for the head of household.

Spousal Employment and Intra-Household Bargaining Power.

PubMed

Antman, Francisca M

2014-05-01

This paper considers the relationship between work status and decision-making power of the head of household and his spouse. I use household fixed effects models to address the possibility that spousal work status maybe correlated with unobserved factors that also affect bargaining power within the home. Consistent with the hypothesis that greater economic resources yield greater bargaining power, I find that the spouse of the head of household is more likely to be involved in decisions when she has been employed. Similarly, the head of household is less likely to be the sole decision-maker when his spouse works.

Spousal Employment and Intra-Household Bargaining Power*

PubMed Central

Antman, Francisca M.

2014-01-01

This paper considers the relationship between work status and decision-making power of the head of household and his spouse. I use household fixed effects models to address the possibility that spousal work status maybe correlated with unobserved factors that also affect bargaining power within the home. Consistent with the hypothesis that greater economic resources yield greater bargaining power, I find that the spouse of the head of household is more likely to be involved in decisions when she has been employed. Similarly, the head of household is less likely to be the sole decision-maker when his spouse works. PMID:25342928

Research and Project Activities in Astrophysics

NASA Technical Reports Server (NTRS)

Harnden, F. Rick, Jr.; Kaluzienski, Louis J. (Technical Monitor)

2002-01-01

In collaboration with G Micela, S. Sciortino, and others at the Osservatorio Astronomico di Palermo G. S. Valens, we conducted studies of X-ray emission from normal stars, primarily via observations of several open star clusters and star forming regions (viz. the Pleiades, NBC 2516, NBC 2264, and the Orion Nebula Cluster). Our work was based on combined data from several X-ray observatories, Einstein, ROSAT, XMM-Newton and Chandra, as well as ground-based optical and radio data. Preliminary results were presented at several meetings: HEAD/AAS, November, 1997 a 195th AAS Meeting, January 2000 a Three Islands Conference, April 2000 a X-ray Astronomy 2000, September 2000 a 197th AAS Meeting, January 2001 Two Years of Science with Chandra, September 2001

BIOMECHANICS OF HEAD INJURY IN OLYMPIC TAEKWONDO AND BOXING

PubMed Central

Fife, G.P.; Pieter, W.

2013-01-01

Objective The purpose was to examine differences between taekwondo kicks and boxing punches in resultant linear head acceleration (RLA), head injury criterion (HIC15), peak head velocity, and peak foot and fist velocities. Data from two existing publications on boxing punches and taekwondo kicks were compared. Methods For taekwondo head impacts a Hybrid II Crash Dummy (Hybrid II) head was instrumented with a tri-axial accelerometer mounted inside the Hybrid II head. The Hybrid II was fixed to a height-adjustable frame and fitted with a protective taekwondo helmet. For boxing testing, a Hybrid III Crash Dummy head was instrumented with an array of tri-axial accelerometers mounted at the head centre of gravity. Results Differences in RLA between the roundhouse kick (130.11±51.67 g) and hook punch (71.23±32.19 g, d = 1.39) and in HIC15 (clench axe kick: 162.63±104.10; uppercut: 24.10±12.54, d = 2.29) were observed. Conclusions Taekwondo kicks demonstrated significantly larger magnitudes than boxing punches for both RLA and HIC. PMID:24744497

The Dearth of UV-bright Stars in M32: Implications for Stellar Evolution Theory

NASA Technical Reports Server (NTRS)

Sweigart, Allen V.; Kimble, Randy A.; Bowers, Charles W.

2008-01-01

Using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope, we have obtained deep far ultraviolet images of the compact elliptical galaxy M32. When combined with earlier near-ultraviolet images of the same field, these data enable the construction of an ultraviolet color-magnitude diagram of the hot horizontal branch (HB) population and other hot stars in late phases of stellar evolution. We find few post-asymptotic giant branch (PAGB) stars in the galaxy, implying that these stars either cross the HR diagram more rapidly than expected, and/or that they spend a significant fraction of their time enshrouded in circumstellar material. The predicted luminosity gap between the hot HB and its AGB-Manque (AGBM) progeny is less pronounced than expected, especially when compared to evolutionary tracks with enhanced helium abundances, implying that the presence of hot HB stars in this metal-rich population is not due to (Delta)Y/(Delta)Z greater than or approx. 4. Only a small fraction (approx. 2%) of the HB population is hot enough to produce significant UV emission, yet most of the W emission in this galaxy comes from the hot HB and AGBM stars, implying that PAGB stars are not a significant source of W emission even in those elliptical galaxies with a weak W excess. Subject headings: galaxies: evolution - galaxies: stellar content - galaxies: individual (M32) - stars: evolution - stars: horizontal branch

Radial head reconstruction in elbow fracture-dislocation: monopolar or bipolar prosthesis?

PubMed

Hartzler, Robert U; Morrey, Bernard F; Steinmann, Scott P; Llusa-Perez, Manuel; Sanchez-Sotelo, Joaquin

2014-07-01

Monopolar and bipolar radial head prosthetic arthroplasties have been used successfully to treat elbow fracture-dislocation with unsalvageable radial head fractures. The relative stability of these two designs in different clinical situations is a topic of ongoing investigation. We tested the effects of monopolar and bipolar fixed-neck prosthetic radial head implants on improvement in elbow coronal and axial plane laxity in a terrible triad biomechanical model that accounted for lateral collateral ligament integrity and the presence of a transverse coronoid fracture. Kinematic data were collected on six fresh-frozen cadaveric upper extremities tested with passive motion throughout the flexion arc. Varus and valgus gravity stress were applied with the wrist in neutral position. A lateral collateral ligament reconstruction was simulated. We assessed instability after radial head resection and reconstruction with either a monopolar or bipolar implant in the presence of a transversely fractured (Regan and Morrey Type 2) or fixed coronoid process. With collateral ligament integrity, no difference was detected, with the numbers available, in valgus laxity between implants under valgus stress (p = 1.0). Laxity improvement with each prosthesis was higher when the coronoid was fractured (mean ± SD: monopolar: 7.4° ± 1.6°, p < 0.001; bipolar: 6.4° ± 1.6°, p = 0.003) than when it was fixed (monopolar: 4.0° ± 1.6°, p = 0.02; bipolar: 4.2° ± 1.6°, p = 0.01). With the numbers available, there was no difference in external rotation laxity between implants under valgus stress (p = 1.0). The greatest stabilizing effect of the prostheses occurred when the coronoid was fractured (monopolar: 3.3° ± 1.2°, p = 0.15; bipolar: 3.3° ± 1.2°, p = 0.17). Radial head arthroplasty offered no substantial stability under varus stress for varus or internal rotation laxity. In our terrible triad cadaveric model, coronoid fixation was effective in improving varus laxity with a monopolar or bipolar prosthesis in place. Also, both types of prostheses were effective in improving valgus and external rotation laxity to the elbow, regardless of coronoid status. With collateral ligaments reconstructed, no large kinematic differences were noted between implants regardless of the varus-valgus position or whether the coronoid was fractured or fixed. The data from our cadaveric model support the use of either implant type in terrible triad injuries if the collateral ligaments are intact or reconstructed.

Stellar motion induced by gravitational instabilities in protoplanetary discs

NASA Astrophysics Data System (ADS)

Michael, Scott; Durisen, R. H.

2010-07-01

We test the effect of assumptions about stellar motion on the behaviour of gravitational instabilities (GIs) in protoplanetary discs around solar-type stars by performing two simulations that are identical in all respects except the treatment of the star. In one simulation, the star is assumed to remain fixed at the centre of the inertial reference frame. In the other, stellar motion is handled properly by including an indirect potential in the hydrodynamic equations to model the star's reference frame as one which is accelerated by star/disc interactions. The discs in both simulations orbit a solar mass star, initially extend from 2.3 to 40 au with a ϖ-1/2 surface density profile, and have a total mass of 0.14 Msolar. The γ = 5/3 ideal gas is assumed to cool everywhere with a constant cooling time of two outer rotation periods. The overall behaviour of the disc evolution is similar, except for weakening in various measures of GI activity by about at most tens of per cent for the indirect potential case. Overall conclusions about disc evolution in earlier papers by our group, where the star was always assumed to be fixed in an inertial frame, remain valid. There is no evidence for independent one-armed instabilities, like the Stimulation by the Long-range Interaction of Newtonian Gravity (SLING), in either simulation. On the other hand, the stellar motion about the system centre of mass (COM) in the simulation with the indirect potential is substantial, up to 0.25 au during the burst phase, as GIs initiate, and averaging about 0.9 au during the asymptotic phase, when the GIs reach an overall balance of heating and cooling. These motions appear to be a stellar response to non-linear interactions between discrete global spiral modes in both the burst and asymptotic phases of the evolution, and the star's orbital motion about the COM reflects the orbit periods of disc material near the corotation radii of the dominant spiral waves. This motion is, in principle, large enough to be observable and could be confused with stellar wobble due to the presence of one or more super-Jupiter mass protoplanets orbiting at 10's au. We discuss why the excursions in our simulation are so much larger than those seen in simulations by Rice et al.

The Tadpole and the Wriggler

NASA Image and Video Library

2014-04-14

A bright blue tadpole appears to swim through the inky blackness of space. Known as IRAS 20324+4057, but dubbed "the Tadpole," this clump of gas and dust has given birth to a bright, "protostar," one of the earliest steps in building a star. This image was taken by NASA's Hubble Space Telescope, and released publicly, in 2012. There are actually multiple protostars within this tadpole's 'head," but the glowing yellow one in this image is the most luminous and massive. When this protostar has gathered together enough mass from its surroundings, it will eventually emerge as a fully-fledged young star. The intense blue glow is caused by nearby stars firing ultraviolet radiation at IRAS 20324+4057, which also sculpts its tail into a long, wiggly shape. In total, this clump spans roughly a light-year from head to tail-tip, and contains gas weighing almost four times the mass of the sun. Framed against a background of distant stars, IRAS 20324+4057 is making its way through the Cygnus OB2 association, a loose cluster of stars some 4,700 light-years from Earth in the constellation Cygnus. This association is one of the largest clusters known, and is famed for its heavyweight members. It contains some of the hottest, most massive and most luminous stars known, some of which are about two million times more luminous than the sun. The Tadpole is not alone in this interstellar pond. Just out of view, to the bottom right of this image, lies another curious object dubbed "the Goldfish" by astronomers. The Goldfish is about half the length of IRAS 20324+4057, and is also thought to be a globule of gas that is being both lit up and sculpted by radiation from cluster stars. Completing this trio is a small clump of blue gas, informally nicknamed "the Wriggler" by some astronomers, visible in the bottom left of this Hubble image. All three objects have the same orientation in the sky and appear to be brighter on their northern sides, leading astronomers to believe they are being shaped by aggressive winds and radiation flowing from hot Cygnus OB2 stars towards the top right of the frame. http://photojournal.jpl.nasa.gov/catalog/PIA18168

Head assembly for multiposition borehole extensometer

DOEpatents

Frank, Donald N.

1983-01-01

A head assembly for a borehole extensometer and an improved extensometer for measuring subsurface subsidence. A plurality of inflatable anchors provide discrete measurement points. A metering rod is fixed to each of the anchors which are displaced when subsidence occurs, thereby translating the attached rod. The head assembly includes a sprocket wheel rotatably mounted on a standpipe and engaged by a chain which is connected at one end to the metering rod and at the other end to a counterweight. A second sprocket wheel connected to the standpipe also engages the chain and drives a connected potentiometer. The head assembly converts the linear displacement of the metering rod to the rotary motion of the second sprocket wheel, which is measured by the potentiometer, producing a continuous electrical output.

Clinical application of a modern high-definition head-mounted display in sonography.

PubMed

Takeshita, Hideki; Kihara, Kazunori; Yoshida, Soichiro; Higuchi, Saori; Ito, Masaya; Nakanishi, Yasukazu; Kijima, Toshiki; Ishioka, Junichiro; Matsuoka, Yoh; Numao, Noboru; Saito, Kazutaka; Fujii, Yasuhisa

2014-08-01

Because of the remarkably improved image quality and wearability of modern head-mounted displays, a monitoring system using a head-mounted display rather than a fixed-site monitor for sonographic scanning has the potential to improve the diagnostic performance and lessen the examiner's physical burden during a sonographic examination. In a preclinical setting, 2 head-mounted displays, the HMZ-T2 (Sony Corporation, Tokyo, Japan) and the Wrap1200 (Vuzix Corporation, Rochester, NY), were found to be applicable to sonography. In a clinical setting, the feasibility of the HMZ-T2 was shown by its good image quality and acceptable wearability. This modern device is appropriate for clinical use in sonography. © 2014 by the American Institute of Ultrasound in Medicine.

48 CFR 23.204 - Procurement exemptions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... PROGRAMS ENVIRONMENT, ENERGY AND WATER EFFICIENCY, RENEWABLE ENERGY TECHNOLOGIES, OCCUPATIONAL SAFETY, AND DRUG-FREE WORKPLACE Energy and Water Efficiency and Renewable Energy 23.204 Procurement exemptions. An agency is not required to procure an ENERGY STAR ® or FEMP-designated product if the head of the agency...

48 CFR 23.204 - Procurement exemptions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... PROGRAMS ENVIRONMENT, ENERGY AND WATER EFFICIENCY, RENEWABLE ENERGY TECHNOLOGIES, OCCUPATIONAL SAFETY, AND DRUG-FREE WORKPLACE Energy and Water Efficiency and Renewable Energy 23.204 Procurement exemptions. An agency is not required to procure an ENERGY STAR ® or FEMP-designated product if the head of the agency...

48 CFR 23.204 - Procurement exemptions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... PROGRAMS ENVIRONMENT, ENERGY AND WATER EFFICIENCY, RENEWABLE ENERGY TECHNOLOGIES, OCCUPATIONAL SAFETY, AND DRUG-FREE WORKPLACE Energy and Water Efficiency and Renewable Energy 23.204 Procurement exemptions. An agency is not required to procure an ENERGY STAR ® or FEMP-designated product if the head of the agency...

The Eagle's EGGs

NASA Astrophysics Data System (ADS)

2001-12-01

VLT ISAAC Looks for Young Stars in the Famous "Pillars of Creation" Summary Through imaging at infrared wavelengths, evidence has been found for recent star formation in the so-called "Pillars of Creation" in the Eagle Nebula (also known as Messier 16 ), made famous when the NASA/ESA Hubble Space Telescope (HST) obtained spectacular visible-wavelength images of this object in 1995. Those huge pillars of gas and dust are being sculpted and illuminated by bright and powerful high-mass stars in the nearby NGC 6611 young stellar cluster . The Hubble astronomers suggested that perhaps even younger stars were forming inside. Using the ISAAC instrument on the VLT 8.2-m ANTU telescope at the ESO Paranal Observatory , European astronomers have now made a wide-field infrared image of the Messier 16 region with excellent spatial resolution, enabling them to penetrate the obscuring dust and search for light from newly born stars . Two of the three pillars are seen to have very young, relatively massive stars in their tips. Another dozen or so lower-mass stars seem to be associated with the small "evaporating gaseous globules (EGGs)" that the Hubble astronomers had discovered scattered over the surface of the pillars. These findings bring new evidence to several key questions about how stars are born . Was the formation of these new stars triggered as the intense ultraviolet radiation from the NGC 6611 stars swept over the pillars, or were they already there? Will the new stars be prematurely cut off from surrounding gas cloud, thus stunting their growth? If the new stars have disks of gas and dust around them, will they be destroyed before they have time to form planetary systems? PR Photo 37a/01 : Full wide-field ISAAC image of the Eagle Nebula. PR Photo 37b/01 : Close-up view of the ISAAC image , showing the famous "Pillars of Creation". PR Photo 37c/01 : Enlargement of the head of Column 1 . PR Photo 37d/01 : Enlargement of the head of Column 2 . PR Photo 37e/01 : Enlargement of the head of Column 4 . PR Video Clip 08a/01 : A "dissolve" between the Hubble visible wavelength and VLT infrared views of the pillars. PR Video Clip 08b/01 : Hubble and VLT views of the head of Column 1 . The famous "Pillars of Creation" Hundreds of millions of people all over the world have admired those towering "Pillars of Creation" in Messier 16 (M16) , also known as the Eagle Nebula , and located in the southern constellation of Serpens. It is one of the most famous NASA/ESA Hubble Space Telescope (HST) images - released in 1995, it has become an icon of modern astronomy, giving the viewer an extraordinary three-dimensional impression of scuba-diving through some leviathan undersea forest. These light-years long columns of gas and dust are being simultaneously sculpted, illuminated, and destroyed by the intense ultraviolet light from massive stars in the adjacent NGC 6611 young stellar cluster . Within a few million years, a mere twinkling of the universal eye, they will be gone forever. But before they are, they have a chance to leave a longer-lasting legacy: a whole new generation of stars may be forming within them. Their formation may have been triggered by the immense power of the NGC 6611 stars, or perhaps they had already started to form quietly earlier on, only to be suddenly subjected to the ravages of an ionising storm front. The real question is then: are there or are there not any new born stars inside those "Pillars of Creation"? The Hubble Space Telescope view When the HST turned to photograph M16 in 1995, it did so using its visible wavelength camera, WFPC-2 . The Hubble astronomers [1] took data through three narrow-bandpass optical filters selecting emission lines from the ionised gas they knew to be present in the region. In doing so, they obtained an extraordinarily sharp view of the well-known pillars of cold gas and dust that are sometimes referred to as "elephant trunks" for obvious reasons. Their image showed the light-years long pillars partly silhouetted against a bright nebular background, and revealed in exquisite detail the surface structure of the pillars as they are being transformed by ultraviolet radiation from massive, hot stars in the NGC 6611 cluster which lies just outside the area covered by the Hubble image. A surprising finding made by the Hubble astronomers was that the pillars are covered with a large number (they counted 73) of small bumps and protrusions which in a few cases are almost completely detached from the pillars. With a typical angular size of only 0.5 arcsec, those objects had not been seen in previous ground-based photographs, and it took the exceptional acuity of Hubble to reveal them. The astronomers dubbed these objects "evaporating gaseous globules" , shortened to "EGGs" . They noted that one or two of these EGGs appeared to have stars right at their tips, and they suggested that perhaps the EGGs are formed as the advancing front of ionised gas driven by the hot NGC 6611 stars is slowed down by the presence of dense knots of gas and dust within the larger pillars. Within those knots then, they hypothesised a population of extremely young stars, still in the womb of their natal cloud but soon to be rudely exposed to a much harsher outside world. However, there was a problem: since their images were taken at visible wavelengths which are relatively easily absorbed by the dust in the EGGs, the Hubble astronomers could not actually see inside the EGGs to test their theory. The VLT looks inside the "Pillars" What was needed then was a survey of the M16 region made at longer wavelengths and penetrating much more deeply through the dense dust. Such a survey should be sensitive enough to detect faint, low-mass young stars deeply embedded in the dusty EGGs. It should have excellent sub-arcsec angular resolution to unambiguously identify an object with a given EGG. And it should cover a wide field-of-view to probe all of the pillars and their surroundings. Over the past twenty years, a number of surveys of M16 have been made at near-infrared, mid-infrared, and millimetre wavelengths. Unfortunately, none of them had this perfect combination of characteristics to answer the crucial question of whether or not there is a population of young stars inside the Eagle's EGGs . However, this past austral autumn (April and May 2001), European astronomers [2] were able to image the Eagle Nebula at near-infrared wavelengths , using the infrared multi-mode ISAAC instrument on the 8.2-m VLT ANTU telescope at ESO's Paranal Observatory in Chile. By specifying that the observations be carried out in so-called "service mode", they ensured that the on-site ESO team could undertake their pre-defined programme under the necessary excellent observing conditions. The results were well worth the effort! The ISAAC near-infrared images cover a 9 x 9 arcmin region, i.e., fourteen times the area seen in the famous Hubble visible image, in three broad-band colours and with sufficient sensitivity to detect young stars of all masses and - most importantly - with an image sharpness as good as 0.35 arcsec. Although this is still some way from the diffraction-limited performance of 0.07 arcsec or better that is now achieved with the adaptive optics system NAOS/CONICA on the VLT telescope (cf. ESO PR 25/01 ), the ISAAC data cover a much wider field-of-view and, vitally, with enough image resolution to probe deep into the individual EGGs . The ISAAC infrared images of Messier 16 ESO PR Photo 37a/01 ESO PR Photo 37a/01 [Preview - JPEG: 400 x 471 pix - 136k] [Normal - JPEG: 800 x 942 pix - 1.2M] [HiRes - JPEG: 3000 x 3532 pix - 12.9M] Caption : ESO PR Photo 37a/01 is a three-colour composite mosaic image of the Eagle Nebula (Messier 16) , based on 144 individual images obtained with the infrared multi-mode instrument ISAAC on the ESO Very Large Telescope (VLT) at the Paranal Observatory. At the centre, the so-called "Pillars of Creation" can be seen. This wide-field infrared image shows not only the central three pillars but also several others in the same star-forming region, as well as a huge number of stars in front of, in, or behind the Eagle Nebula. The cluster of bright blue stars to the upper right is NGC 6611 , home to the massive and hot stars that illuminate the pillars. Technical information about this photo is available below. ESO PR Photo 37b/01 ESO PR Photo 37b/01 [Preview - JPEG: 400 x 553 pix - 160k] [Normal - JPEG: 800 x 1105 pix - 1.2M] [FullRes - JPEG: 1330 x 1837 pix - 2.7M] Caption : ESO PR Photo 37b/01 shows a zoom into the centre of PR Photo 37a/01 , with the infrared view of the columns and their immediate surroundings in more detail. The pillars or columns are numbered 1 to 3 from left to right (east to west). The pillars themselves are less prominent than on the Hubble visible-light image of this region - this because near-infrared light penetrates the thinner parts of the gas and dust clouds and only the heads remain opaque. A number of red objects can be seen associated with the pillars: some of these are just background sources seen through the dust, but some are probably real young stars embedded in the pillars. The purple arc near the bottom of the picture is Herbig-Haro object 216 , a fast-moving clump of heated gas emanating from a young star (see also PR Photo 37e/01 ). Technical information about this photo is available below. HST and VLT images of the Eagle Nebula - PR Video Clip 08a/01] ESO PR Video Clip 08a/01 HST and VLT images of the Eagle Nebula (52 frames/0:02 min) [MPEG Video; 160x120 pix; 3.6Mb] ESO Video Clip 08a/01 shows a sky field similar to that seen in PR Photo 37b/01 , "dissolving" back and forth between the Hubble and VLT views, demonstrating the dramatic changes that occur when changing wavelength from the visible to near-infrared. (It is suggested to play it at reduced speed). The wide-field view of M16 ( Photo 37a/01 ) shows that there is much more to the region than is seen in the Hubble image. The first impression one gets is of an enormous number of stars. Those which are blue in the infrared image are either members of the young NGC 6611 cluster - whose massive stars are concentrated in the upper right (north west) part of the field - or foreground stars which happen to lie along the line of sight towards M16. Most of the stars are fainter and more yellow. They are ordinary stars behind M16, along the line of sight through the galactic bulge, and are seen through the molecular clouds out of which NGC 6611 formed. Some very red stars are also seen: these are either very young and embedded in gas and dust clouds, or just brighter stars in the background shining through them. Zooming in, Photo 37b/01 shows the region of the pillars covered by the Hubble image and its immediate surroundings. The pillars are still obvious, although appearing less prominent in places as one penetrates the thinner parts, getting closer to the goal of probing inside the pillars. Video Clip 08a/01 shows how this appearance changes in a continuous dissolve between the Hubble visible wavelength view and its VLT infrared equivalent. Hunting for new stars in the EGGs ESO PR Photo 37c/01 ESO PR Photo 37c/01 [Preview - JPEG: 400 x 371 pix - 66k] [Normal - JPEG: 800 x 741 pix - 352k] Caption : ESO PR Photo 37c/01 shows an enlarged view of the head of the largest of the three main pillars, Column 1. The head is almost transparent around the edges at near-infrared wavelengths, but there is still a substantial opaque core which even these near-infrared VLT observations cannot penetrate. The complex blueish nebulosity bisected by a dark lane near the tip is being lit up by the bright yellow star just below it, which appears to be very young and rather massive. Several of the much fainter stars to the right of and below this source are found to be associated with EGGs seen in the Hubble image, and these all have much lower masses. Finally, there is a faint streak of blue light emanating from from the tip of EGG 23, one of the darkest parts of Column 1, ending in a blue blob further north. An equal distance to the south of the EGG and off the head, there is another curving blue nebulosity. These features are also seen in the Hubble image, and may be part of a Herbig-Haro jet coming from a young star buried deeply in EGG 23 and invisible in this image. Technical information about this photo is available below. ESO PR Photo 37d/01 ESO PR Photo 37d/01 [Preview - JPEG: 400 x 362 pix - 75k] [Normal - JPEG: 800 x 724 pix - 372k] Caption : ESO PR Photo 37d/01 shows a similarly enlarged view of the head of Column 2. The bright blue-yellow source embedded in nebulosity near the tip is another young star unseen in the Hubble images: although it appears to be double here, it is in fact just one relatively massive young star surrounding by nebulosity. Technical information about this photo is available below. ESO PR Photo 37e/01 ESO PR Photo 37e/01 [Preview - JPEG: 400 x 365 pix - 112k] [Normal - JPEG: 800 x 729 pix - 536k] Caption : ESO PR Photo 37e/01 shows an enlarged view of the head of Column 4, which lies to the lower-left in Photo 37a/01 and was not covered in the Hubble image. This column is similar to the more familiar ones, but thus far less impacted by the massive stars in NGC6611. The two red nebulosities in the head signpost one or more young stars so deeply embedded that they cannot be seen directly in the VLT infrared image, only indirectly as they illuminate dust around them. One of these sources is thought to be the origin of the Herbig-Haro object HH216 seen in Photo 37a/01 and Photo 37b/01 [3]. Technical information about this photo is available below. Pillars of Creation in Eagle Nebula (Column 1) - PR Video Clip 08b/01] ESO PR Video Clip 08b/01 Pillars of Creation in Eagle Nebula (Column 1) (800 frames/0:32 min) [MPEG Video+Audio; 192x144 pix; 4.0M] [MPEG Video+Audio; 384x288 pix; 9.8M] [RealMedia; streaming; 56kps] [RealMedia; streaming; 200kps] ESO PR Video Clip 08b/01 shows the Hubble and VLT views of the head of Column 1 (cf. Photo 37c/01 ), with an additional zoom-in. Note that the bright complex reflection nebulosity and its young, massive energy source are completely unseen at visible wavelengths. Photos 37c-e/01 show even further close-ups of the heads of Columns 1 and 2, plus Column 4, seen in the wide-field ISAAC image ( Photo 37a/01 ) towards the lower left (south east). The young star in the head of Column 1 ( Photo 37c/01 ) is located within a complex reflection nebula, completely unseen at visible wavelengths. From the near-infrared brightness of the star, the astronomers judge it to be more massive than our own sun and very young (in astronomical terms), perhaps only 100,000 years old. Video Clip 08b/01 allows a direct comparison between the Hubble and VLT views of this region. Right at the tip of Column 2 ( Photo 37d/01 ), another young star also illuminates a small reflection nebula, again undetected in the Hubble image. And to the south-east, the head of Column 4 ( Photo 37e/01 ) shows complex red nebulosity which the astronomers take to be the signpost of very young objects, so deeply embedded that they are not directly detected in the VLT images. The present team of astronomers has recently investigated this object [3] and believe it is hiding the driving source of a so-called "Herbig-Haro jet", a speedy outflow of gas that can be seen where it ends in a shock, the bright purple arc at the lower edge of Photo 37b/01 . Turning to smaller scales, the astronomers made a very accurate alignment of the Hubble and VLT images, and then examined the location of each EGG, searching for stars within them. This search had to be carried out very carefully, given the small sizes of the EGGs, and also because, once in a while, a perfectly ordinary background star might seem to be aligned with an EGG purely by chance. After completing their search, they found that 11 of the 73 EGGs clearly have stars associated with them. Only one of these had been previously been seen in the Hubble images, and another five EGGs were noted as possibly containing stars. Judging from their near-infrared brightness, most of these stars seem to be less massive than our Sun. Interestingly, most of the EGGs with stars are located on Column 1, and roughly half of them right at the tip of the head, not far from the more massive star that illuminates the reflection nebula. This may be evidence for a small cluster of young stars associated with Column 1 which will soon be revealed as the column is eaten away. Even though the remaining 57 EGGs appear to be empty, it is important to note that there may nevertheless be more young stars in the M16 pillars. After all, neither of the bright young stars at the tips of Columns 1 and 2 are related to any of the Hubble EGGs. Also, it is clear from the VLT image that parts of the pillars and a few of the EGGs are so dense that they remain completely opaque even at near-infrared wavelengths, and may still be harbouring other new stars. An interesting example is the apparently empty EGG number 23, from which another high-speed Herbig-Haro jet seems to be emerging ( Photo 37c/01 ). Outlook The new VLT infrared image shows that there is now firm evidence for the recent birth of stars in the Eagle Nebula and that at least some of the Eagle's EGGs are fertile, not sterile! A deeper look at even longer wavelengths will be needed to make a complete census of all the star formation in the Eagle Nebula, perhaps using the VLT thermal-infrared camera, VISIR , when it becomes available or, ultimately, less than a decade from now, the infrared-optimised Next Generation Space Telescope (NGST) , the NASA/ESA/CSA successor to the HST. At longer wavelengths, observations with the planned Atacama Large Millimeter Array (ALMA) will also be most useful. From images alone, however, it is not possible to tell which came first: the stars or the EGGs? Were those young stars already forming inside dark clouds before the intense ultraviolet radiation of the nearby massive hot stars swept over the pillars? Or did that radiation compress empty clumps in those clouds and trigger the birth of the stars? In either case, those young stars will soon be exposed to the full fury of the ionisation storm as the columns are evaporated. How will their fate have been affected? Ripped prematurely from the cloud, they will be cut off from the reservoir of material from which they grew, and thus may end up smaller than would otherwise be expected. Also, the dense disks of gas and dust known to girdle young stars will suddenly be heated and boiled away by the ultraviolet radiation, as has been seen happening in the Orion Nebula, perhaps preventing the formation of planets around those stars. Theoreticians studying these problems now have some new data to work with. Nevertheless, to keep things in perspective, it is important to remember that the towering pillars cover only a small fraction of the Eagle Nebula. While a few tens of new stars may be forming in the pillars today, at least a thousand young stars were born in the adjacent NGC 6611 cluster within the last few million years, including the massive stars themselves. The story of the formation of that cluster may be something else altogether, but perhaps just as spectacular. More information The research described in this press release is presented in more detail in a research paper ("The Eagle's EGGs: fertile or sterile?"), to be submitted to the European research journal "Astronomy & Astrophysics Letters". The work has been carried under the auspices of the European Commission Research Training Network "The Formation and Evolution of Young Stellar Clusters" (HPRN-CT-2000-00155) [4]. Notes [1] The Hubble Space Telescope team consisted of Jeff Hester and Paul Scowen (Arizona State University, USA) and 21 collaborators. Their M16 image was made at visible wavelengths using the Wide-Field Planetary Camera 2 (WFPC-2) instrument of the HST, selecting the emission lines of double ionised oxygen [OIII], the hydrogen line H-alpha, and single ionised sulphur [SII] in the visible wavelength interval (from 500 to 671 nm). The image was released by the Space Telescope Science Institute (PR95-44) in 1995 and the scientific data analysis was published by Jeff Hester et al. in the Astronomical Journal in 1996 (Vol. 111, p. 2349). [2] The present team consists of Mark McCaughrean and Morten Andersen , both of the Astrophysical Institute Potsdam (AIP), Germany. [3] A research paper discussing the embedded object in the head of Column 4 and its role in driving the Herbig-Haro jet ending in HH 216 ("Molecular cloud structure and star formation near HH216 in M16", by Morten Andersen, Jens Knude, Bo Reipurth, Alain Castets, Lars-Åke Nyman, Mark McCaughrean and Steve Heathcote) has been submitted for publication in the European research journal "Astronomy & Astrophysics". [4]: Mark McCaughrean would like to dedicate these VLT images of the Eagle Nebula to his own new baby star, Finn, born in Berlin on December 1st, 2001, when his father was working on them and also to Sybille and Catriona, the other stars in his family cluster! Technical information about the photos PR Photo 37a/01 of the Eagle Nebula, M16, and NGC 6611 was made using the near-infrared camera ISAAC on the ESO 8.2-m VLT ANTU telescope on April 8 and May 8 - 10, 2001. The full field measures approximately 9.1 x 9.1 arcmin, covering roughly 17 x 17 light-years (5.3 x 5.3 pc) at the distance to the region (about 6500 light-years or 2 kpc). This required a 16-position mosaic (4 x 4 grid) of ISAAC pointings: at each pointing, a series of images were taken in each of the near-infrared J s - (centred at 1.24 µm wavelength), H- (1.65µm), and K s - (2.16 µm) bands. North is up and East left in this and all subsequent images. The total integration time for each pixel in the mosaic was 1200, 300, and 300 seconds in the central 4.5 x 4.5 arcmin region, and 200, 50, and 50 seconds in the outer part, in J s -, H-, and K s - bands, respectively. The seeing FWHM (full width at half maximum) was excellent, at 0.38, 0.36, and 0.33 arcsec in J s , H, and K s , respectively. Point sources are detected in the central region at the 3-sigma level (brightest pixel above background noise) at 22.6, 21.3, and 20.4 magnitudes in J s , H, and K s , respectively. These limits imply that a 1 million year old, 0.075 solar-mass object on the star/brown dwarf boundary could be detected in M16 through roughly 15, 20, and 30 magnitudes of visual extinction at J s , H, and K s , respectively. After removal of instrumental signatures and the bright infrared sky background, all frames in a given band were carefully aligned and adjusted to form a seamless mosaic. The three monochromatic mosaics were then scaled to the cube root of their intensities to reduce the enormous dynamic range and enhance faint nebular features. The mosaics were then combined to create the colour-coded image, with the J s -band being rendered as blue, the H-band as green, and the K s -band as red. A total of 144 individual 1024 x 1024 pixel ISAAC images were merged to form this mosaic. PR Photo 37b/01 shows an enlarged section of the full mosaic covering 6.2 x 7.5 light-years (1.9 x 2.3 pc) centred on the pillars. PR Photos 37c-e/01 show smaller, enlarged sections covering the head of each of Columns 1, 2, and 4, respectively. In each case, the region shown measures 1.9 x 2.8 light-years (0.6 x 0.9 pc). The intensity scalings have been adjusted to better show the young stars embedded in the head of each column.

HUBBLE VIEWS A STARRY RING WORLD BORN IN A HEAD-ON COLLISION

NASA Technical Reports Server (NTRS)

2002-01-01

[Right] - A rare and spectacular head-on collision between two galaxies appears in this NASA Hubble Space Telescope true-color image of the Cartwheel Galaxy, located 500 million light-years away in the constellation Sculptor. The new details of star birth resolved by Hubble provide an opportunity to study how extremely massive stars are born in large fragmented gas clouds. The striking ring-like feature is a direct result of a smaller intruder galaxy -- possibly one of two objects to the right of the ring -- that careened through the core of the host galaxy. Like a rock tossed into a lake, the collision sent a ripple of energy into space, plowing gas and dust in front of it. Expanding at 200,000 miles per hour, this cosmic tsunami leaves in its wake a firestorm of new star creation. Hubble resolves bright blue knots that are gigantic clusters of newborn stars and immense loops and bubbles blown into space by exploding stars (supernovae) going off like a string of firecrackers. The Cartwheel Galaxy presumably was a normal spiral galaxy like our Milky Way before the collision. This spiral structure is beginning to re-emerge, as seen in the faint arms or spokes between the outer ring and bulls-eye shaped nucleus. The ring contains at least several billion new stars that would not normally have been created in such a short time span and is so large (150,000 light-years across) our entire Milky Way Galaxy would fit inside. Hubble's new view does not solve the mystery as to which of the two small galaxies might have been the intruder. The blue galaxy is disrupted and has new star formation which strongly suggests it is the interloper. However, the smoother-looking companion has no gas, which is consistent with the idea that gas was stripped out of it during passage through the Cartwheel Galaxy. [Top Left] - Hubble's detailed view shows the knot-like structure of the ring, produced by large clusters of new star formation. Hubble also resolves the effects of thousands of supernovae on the ring structure. One flurry of explosions blew a hole in the ring and formed a giant bubble of hot gas. Secondary star formation on the edge of this bubble appears as an arc extending beyond the ring. [Bottom Left] - Hubble resolves remarkable new detail in the galaxy's core. The reddish color of this region indicates that it contains a tremendous amount of dust and embedded star formation. Bright pinpoints of light are gigantic young star clusters. The picture was taken with the Wide Field Planetary Camera-2 on October 16, 1994. It is a combination of two images, taken in blue and near-infrared light. Credit: Kirk Borne (ST ScI), and NASA

Evidence for halo kinematics among cool carbon-rich dwarfs

NASA Astrophysics Data System (ADS)

Farihi, J.; Arendt, A. R.; Machado, H. S.; Whitehouse, L. J.

2018-07-01

This paper reports preliminary, yet compelling, kinematical inferences for N≳ 600 carbon-rich dwarf stars that demonstrate around 30-60 per cent are members of the Galactic halo. The study uses a spectroscopically and non-kinematically selected sample of stars from the SDSS, and cross-correlates these data with three proper motion catalogues based on Gaia DR1 astrometry to generate estimates of their 3D space velocities. The fraction of stars with halo-like kinematics is roughly 30 per cent for distances based on a limited number of parallax measurements, with the remainder dominated by the thick disc, but close to 60 per cent of the sample lies below an old, metal-poor disc isochrone in reduced proper motion. An ancient population is consistent with an extrinsic origin for C/O >1 in cool dwarfs, where a fixed mass of carbon pollution more readily surmounts lower oxygen abundance and with a lack of detectable ultraviolet-blue flux from younger white dwarf companions. For an initial stellar mass function that favours low-mass stars as in the Galactic disc, the dC stars are likely to be the dominant source of carbon-enhanced, metal-poor stars in the Galaxy.

Evidence for halo kinematics among cool carbon-rich dwarfs

NASA Astrophysics Data System (ADS)

Farihi, J.; Arendt, A. R.; Machado, H. S.; Whitehouse, L. J.

2018-04-01

This paper reports preliminary yet compelling kinematical inferences for N ≳ 600 carbon-rich dwarf stars that demonstrate around 30% to 60% are members of the Galactic halo. The study uses a spectroscopically and non-kinematically selected sample of stars from the SDSS, and cross-correlates these data with three proper motion catalogs based on Gaia DR1 astrometry to generate estimates of their 3-D space velocities. The fraction of stars with halo-like kinematics is roughly 30% for distances based on a limited number of parallax measurements, with the remainder dominated by the thick disk, but close to 60% of the sample lie below an old, metal-poor disk isochrone in reduced proper motion. An ancient population is consistent with an extrinsic origin for C/O >1 in cool dwarfs, where a fixed mass of carbon pollution more readily surmounts lower oxygen abundances, and with a lack of detectable ultraviolet-blue flux from younger white dwarf companions. For an initial stellar mass function that favors low-mass stars as in the Galactic disk, the dC stars are likely to be the dominant source of carbon-enhanced, metal-poor stars in the Galaxy.

SU-E-T-109: An Investigation of Including Variable Relative Biological Effectiveness in Intensity Modulated Proton Therapy Planning Optimization for Head and Neck Cancer Patients

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

Cao, W; Zaghian, M; Lim, G

2015-06-15

Purpose: The current practice of considering the relative biological effectiveness (RBE) of protons in intensity modulated proton therapy (IMPT) planning is to use a generic RBE value of 1.1. However, RBE is indeed a variable depending on the dose per fraction, the linear energy transfer, tissue parameters, etc. In this study, we investigate the impact of using variable RBE based optimization (vRBE-OPT) on IMPT dose distributions compared by conventional fixed RBE based optimization (fRBE-OPT). Methods: Proton plans of three head and neck cancer patients were included for our study. In order to calculate variable RBE, tissue specific parameters were obtainedmore » from the literature and dose averaged LET values were calculated by Monte Carlo simulations. Biological effects were calculated using the linear quadratic model and they were utilized in the variable RBE based optimization. We used a Polak-Ribiere conjugate gradient algorithm to solve the model. In fixed RBE based optimization, we used conventional physical dose optimization to optimize doses weighted by 1.1. IMPT plans for each patient were optimized by both methods (vRBE-OPT and fRBE-OPT). Both variable and fixed RBE weighted dose distributions were calculated for both methods and compared by dosimetric measures. Results: The variable RBE weighted dose distributions were more homogenous within the targets, compared with the fixed RBE weighted dose distributions for the plans created by vRBE-OPT. We observed that there were noticeable deviations between variable and fixed RBE weighted dose distributions if the plan were optimized by fRBE-OPT. For organs at risk sparing, dose distributions from both methods were comparable. Conclusion: Biological dose based optimization rather than conventional physical dose based optimization in IMPT planning may bring benefit in improved tumor control when evaluating biologically equivalent dose, without sacrificing OAR sparing, for head and neck cancer patients. The research is supported in part by National Institutes of Health Grant No. 2U19CA021239-35.« less

Rapidly rotating polytropes in general relativity

NASA Technical Reports Server (NTRS)

Cook, Gregory B.; Shapiro, Stuart L.; Teukolsky, Saul A.

1994-01-01

We construct an extensive set of equilibrium sequences of rotating polytropes in general relativity. We determine a number of important physical parameters of such stars, including maximum mass and maximum spin rate. The stability of the configurations against quasi-radial perturbations is diagnosed. Two classes of evolutionary sequences of fixed rest mass and entropy are explored: normal sequences which behave very much like Newtonian evolutionary sequences, and supramassive sequences which exist solely because of relativistic effects. Dissipation leading to loss of angular momentum causes a star to evolve in a quasi-stationary fashion along an evolutionary sequence. Supramassive sequences evolve towards eventual catastrophic collapse to a black hole. Prior to collapse, the star must spin up as it loses angular momentum, an effect which may provide an observational precursor to gravitational collapse to a black hole.

Technology of welding aluminum alloys-IV

NASA Technical Reports Server (NTRS)

Ginez, R.; Lewis, J. R.; Millett, A. U.; Saenger, K. A.; Skelly, J. K.; Standiford, V. E.; Whiteman, J. O.

1978-01-01

Skate-weld carriage and track assembly were developed for controlled fusion welding on compound-curvature surfaces. Unlike fixed-position carriage used for vertical, horizontal, and circumferential welding, carriage has suspension system that permits angular positioning of weld head on carriage. It also has carriage-and-drive track mechanism capable of traveling over compound curvatures. Carriage is designed with universal mounting platform so that slim tools, weld heads, or X-ray units can be interchanged without need for realinement.

Non-LTE, line-blanketed model atmospheres for late O- and early B-type stars

NASA Technical Reports Server (NTRS)

Grigsby, James A.; Morrison, Nancy D.; Anderson, Lawrence S.

1992-01-01

The use of non-LTE line-blanketed model atmospheres to analyze the spectra of hot stars is reported. The stars analyzed are members of clusters and associations, have spectral types in the range O9-B2 and luminosity classes in the range III-IV, have slow to moderate rotation, and are photometrically constant. Sampled line opacities of iron-group elements were incorporated in the radiative transfer solution; solar abundances were assumed. Good to excellent agreement is obtained between the computed profiles and essentially all the line profiles used to fix the model, and reliable stellar parameters are derived. The synthetic M II 5581 equivalent widths agree well with the observed ones at the low end of the temperature range studied, but, above 25,000 K, the synthetic line is generally stronger than the observed line. The behavior of the observed equivalent widths of N II, N III, C II and C III lines as a function of Teff is studied. Most of the lines show much scatter, with no consistent trend that could indicate abundance differences from star to star.

Silicon monoxide in the 4 micron infrared spectrum of long-period variables

NASA Technical Reports Server (NTRS)

Hinkle, K. H.; Barnes, T. G.; Lambert, D. L.; Beer, R.

1976-01-01

The first-overtone sequence of vibration-rotation transitions of the free radical silicon monoxide are shown to have extreme phase-dependent variations in the spectra of two M-type long-period variables, Omicron Ceti and R Leonis, and the mild S-type long-period variable, Chi Cygni. At maximum light, the SiO band heads are not detectable. Near minimum light, the band heads of (Si-25)O are detected in the 4-micron spectra of all three stars. The band heads of the terrestrially less abundant isotopic species, (Si-29)O and (Si-30)O, are detected in Chi Cygni. Possible explanations of the phase-dependent behavior are discussed, and the role of the stellar chromosphere is considered.

Gender Discrimination in the Allocation of Migrant Household Resources*

PubMed Central

Antman, Francisca M.

2016-01-01

This paper considers the relationship between international migration and gender discrimination through the lens of decision-making power over intrahousehold resource allocation. The endogeneity of migration is addressed with a difference-in-differences style identification strategy and a model with household fixed effects. The results suggest that while a migrant household head is away, a greater share of resources is spent on girls relative to boys and his spouse commands greater decision-making power. Once the head returns home, however, a greater share of resources goes to boys and there is suggestive evidence of greater authority for the head of household. PMID:27546986

KSC-2011-1860

NASA Image and Video Library

2011-02-25

CAPE CANAVERAL, Fla. -- Crew members of Liberty Star, one of NASA's solid rocket booster retrieval ships, hold on tightly to handle grips as the swells of the Atlantic Ocean cause the vessel to pitch and roll while heading toward the recovery area where the right spent booster splashed down after Discovery's final launch. The shuttle’s two solid rocket booster casings and associated flight hardware are recovered in the Atlantic Ocean after every launch by Freedom Star and Liberty Star. The boosters impact the Atlantic about seven minutes after liftoff and the retrieval ships are stationed about 10 miles from the impact area at the time of splashdown. After the spent segments are processed, they will be transported to Utah, where they will be refurbished and stored, if needed. Photo credit: NASA/Frank Michaux

THE TRIFID NEBULA: STELLAR SIBLING RIVALRY

NASA Technical Reports Server (NTRS)

2002-01-01

This NASA Hubble Space Telescope image of the Trifid Nebula reveals a stellar nursery being torn apart by radiation from a nearby, massive star. The picture also provides a peek at embryonic stars forming within an ill-fated cloud of dust and gas, which is destined to be eaten away by the glare from the massive neighbor. This stellar activity is a beautiful example of how the life cycles of stars like our Sun is intimately connected with their more powerful siblings. The Hubble image shows a small part of a dense cloud of dust and gas, a stellar nursery full of embryonic stars. This cloud is about 8 light-years away from the nebula's central star, which is beyond the top of this picture. Located about 9,000 light-years from Earth, the Trifid resides in the constellation Sagittarius. A stellar jet [the thin, wispy object pointing to the upper left] protrudes from the head of a dense cloud and extends three-quarters of a light-year into the nebula. The jet's source is a very young stellar object that lies buried within the cloud. Jets such as this are the exhaust gases of star formation. Radiation from the massive star at the center of the nebula is making the gas in the jet glow, just as it causes the rest of the nebula to glow. The jet in the Trifid is a 'ticker tape,' telling the history of one particular young stellar object that is continuing to grow as its gravity draws in gas from its surroundings. But this particular ticker tape will not run for much longer. Within the next 10,000 years the glare from the central, massive star will continue to erode the nebula, overrunning the forming star, and bringing its growth to an abrupt and possibly premature end. Another nearby star may have already faced this fate. The Hubble picture shows a 'stalk' [the finger-like object] pointing from the head of the dense cloud directly toward the star that powers the Trifid. This stalk is a prominent example of the evaporating gaseous globules, or 'EGGs,' that were seen previously in the Eagle Nebula, another star-forming region photographed by Hubble. The stalk has survived because at its tip there is a knot of gas that is dense enough to resist being eaten away by the powerful radiation. Reflected starlight at the tip of the EGG may be due to light from the Trifid's central star, or from a young stellar object buried within the EGG. Similarly, a tiny spike of emission pointing outward from the EGG looks like a small stellar jet. Hubble astronomers are tentatively interpreting this jet as the last gasp from a star that was cut off from its supply lines 100,000 years ago. The images were taken Sept. 8, 1997 through filters that isolate emission from hydrogen atoms, ionized sulfur atoms, and doubly ionized oxygen atoms. The images were combined in a single color composite picture. While the resulting picture is not true color, it is suggestive of what a human eye might see. Credits: NASA and Jeff Hester (Arizona State University)

Stellar equilibrium configurations of compact stars in f ( R , T ) theory of gravity

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

Moraes, P.H.R.S.; Arbañil, José D.V.; Malheiro, M., E-mail: moraes.phrs@gmail.com, E-mail: arbanil@ita.br, E-mail: malheiro@ita.br

In this article we study the hydrostatic equilibrium configuration of neutron stars and strange stars, whose fluid pressure is computed from the equations of state p =ωρ{sup 5/3} and p =0.28(ρ−4B), respectively, with ω and B being constants and ρ the energy density of the fluid. We start by deriving the hydrostatic equilibrium equation for the f ( R , T ) theory of gravity, with R and T standing for the Ricci scalar and trace of the energy-momentum tensor, respectively. Such an equation is a generalization of the one obtained from general relativity, and the latter can be retrievedmore » for a certain limit of the theory. For the f ( R , T )= R +2λ T functional form, with λ being a constant, we find that some physical properties of the stars, such as pressure, energy density, mass and radius, are affected when λ is changed. We show that for a fixed central star energy density, the mass of neutron and strange stars can increase with λ. Concerning the star radius, it increases for neutron stars and it decreases for strange stars with the increment of λ. Thus, in f ( R , T ) theory of gravity we can push the maximum mass above the observational limits. This implies that the equation of state cannot be eliminated if the maximum mass within General Relativity lies below the limit given by observed pulsars.« less

Stellar equilibrium configurations of compact stars in f(R,T) theory of gravity

NASA Astrophysics Data System (ADS)

Moraes, P. H. R. S.; Arbañil, José D. V.; Malheiro, M.

2016-06-01

In this article we study the hydrostatic equilibrium configuration of neutron stars and strange stars, whose fluid pressure is computed from the equations of state p=ωρ5/3 and p=0.28(ρ-4Script B), respectively, with ω and Script B being constants and ρ the energy density of the fluid. We start by deriving the hydrostatic equilibrium equation for the f(R,T) theory of gravity, with R and T standing for the Ricci scalar and trace of the energy-momentum tensor, respectively. Such an equation is a generalization of the one obtained from general relativity, and the latter can be retrieved for a certain limit of the theory. For the f(R,T)=R+2λ T functional form, with λ being a constant, we find that some physical properties of the stars, such as pressure, energy density, mass and radius, are affected when λ is changed. We show that for a fixed central star energy density, the mass of neutron and strange stars can increase with λ. Concerning the star radius, it increases for neutron stars and it decreases for strange stars with the increment of λ. Thus, in f(R,T) theory of gravity we can push the maximum mass above the observational limits. This implies that the equation of state cannot be eliminated if the maximum mass within General Relativity lies below the limit given by observed pulsars.

Influence of gravity on the spatial orientation of eye nystagmus induced by unilateral lesion of horizontal semicircular canal.

PubMed

Pettorossi, V E; Ermanno, M; Pierangelo, E; Silvarosa, G

2000-03-01

The influence of gravity in the orientation and slow phase eye velocity of the ocular nystagmus following unilateral damage of the cupula in the ampulla of the horizontal semicircular canal (UHCD) was investigated. The nystagmus was analysed at different sagittal head positions using the x-y infrared eye monitor technique. The nystagmus was almost horizontal at 0 degrees head pitch angle and remained partially fixed in space when the head was pitched upward or downward. The reorientation gain of the slow and quick phases was high (about 0.75) within +/- 45 degrees of head pitch angle, but beyond this range, it decreased greatly. The gain value depended on the lesion extension to otolithic receptors. The absolute value of the slow phase eye velocity of UHCD nystagmus was also modified systematically by the head pitch, showing a reduction in the upward and an increase in the downward.

Comparison of smooth pursuit and combined eye-head tracking in human subjects with deficient labyrinthine function

NASA Technical Reports Server (NTRS)

Leigh, R. J.; Thurston, S. E.; Sharpe, J. A.; Ranalli, P. J.; Hamid, M. A.

1987-01-01

The effects of deficient labyrinthine function on smooth visual tracking with the eyes and head were investigated, using ten patients with bilateral peripheral vestibular disease and ten normal controls. Active, combined eye-head tracking (EHT) was significantly better in patients than smooth pursuit with the eyes alone, whereas normal subjects pursued equally well in both cases. Compensatory eye movements during active head rotation in darkness were always less in patients than in normal subjects. These data were used to examine current hypotheses that postulate central cancellation of the vestibulo-ocular reflex (VOR) during EHT. A model that proposes summation of an integral smooth pursuit command and VOR/compensatory eye movements is consistent with the findings. Observation of passive EHT (visual fixation of a head-fixed target during en bloc rotation) appears to indicate that in this mode parametric gain changes contribute to modulation of the VOR.

Modeling and Simulation of Hydropower Station Diversion System's characteristic line method by introducing water head to flow feedback

NASA Astrophysics Data System (ADS)

Guangwen, Xu; Xi, Li; Ze, Yao

2018-06-01

To solve the damping problem of water hammer wave in the modeling method of water diversion system of hydropower station, this paper introduces the feedback regulation technology from head to flow, that is: A fixed water head is taken out for flow feedback, and the following conclusions are obtained through modeling and simulation. Adjusting the feedback coefficient F of the water head to the flow rate can change the damping characteristic of the system, which can simulate the attenuation process of the water shock wave in the true water diversion pipeline. Even if a small feedback coefficient is introduced, the damping effect of the system is very obvious, but it has little effect on the amplitude of the first water shock wave after the transition process. Therefore, it is feasible and reasonable to introduce water head to flow rate feedback coefficient F in hydraulic turbine diversion system.

Long-term imaging in awake mice using removable cranial windows

PubMed Central

Glickfeld, Lindsey L.; Kerlin, Aaron M.; Reid, R. Clay; Bonin, Vincent; Schafer, Dorothy P.; Andermann, Mark L.

2015-01-01

Cranial window implants in head-fixed rodents are becoming a preparation of choice for stable optical access to large areas of cortex over extended periods of time. Here, we provide a highly detailed and reliable surgical protocol for a cranial window implantation procedure for chronic widefield and cellular imaging in awake, head-fixed mice, which enables subsequent window removal and replacement in the weeks and months following the initial craniotomy. This protocol has facilitated awake, chronic imaging in adolescent as well as adult mice over several months from a large number of cortical brain regions; targeted virus and tracer injections from data obtained using prior awake functional mapping; and functionally-targeted two-photon imaging across all cortical layers in awake mice using a microprism attachment to the cranial window. Collectively, these procedures extend the reach of chronic imaging of cortical function and dysfunction in behaving animals. PMID:25275789

Two-photon calcium imaging from head-fixed Drosophila during optomotor walking behavior.

PubMed

Seelig, Johannes D; Chiappe, M Eugenia; Lott, Gus K; Dutta, Anirban; Osborne, Jason E; Reiser, Michael B; Jayaraman, Vivek

2010-07-01

Drosophila melanogaster is a model organism rich in genetic tools to manipulate and identify neural circuits involved in specific behaviors. Here we present a technique for two-photon calcium imaging in the central brain of head-fixed Drosophila walking on an air-supported ball. The ball's motion is tracked at high resolution and can be treated as a proxy for the fly's own movements. We used the genetically encoded calcium sensor, GCaMP3.0, to record from important elements of the motion-processing pathway, the horizontal-system lobula plate tangential cells (LPTCs) in the fly optic lobe. We presented motion stimuli to the tethered fly and found that calcium transients in horizontal-system neurons correlated with robust optomotor behavior during walking. Our technique allows both behavior and physiology in identified neurons to be monitored in a genetic model organism with an extensive repertoire of walking behaviors.

Magnetic eye tracking in mice

PubMed Central

Payne, Hannah L

2017-01-01

Eye movements provide insights about a wide range of brain functions, from sensorimotor integration to cognition; hence, the measurement of eye movements is an important tool in neuroscience research. We describe a method, based on magnetic sensing, for measuring eye movements in head-fixed and freely moving mice. A small magnet was surgically implanted on the eye, and changes in the magnet angle as the eye rotated were detected by a magnetic field sensor. Systematic testing demonstrated high resolution measurements of eye position of <0.1°. Magnetic eye tracking offers several advantages over the well-established eye coil and video-oculography methods. Most notably, it provides the first method for reliable, high-resolution measurement of eye movements in freely moving mice, revealing increased eye movements and altered binocular coordination compared to head-fixed mice. Overall, magnetic eye tracking provides a lightweight, inexpensive, easily implemented, and high-resolution method suitable for a wide range of applications. PMID:28872455

Neurobehavioural assessment and diagnosis in disorders of consciousness: a preliminary study of the Sensory Tool to Assess Responsiveness (STAR).

PubMed

Stokes, Verity; Gunn, Sarah; Schouwenaars, Katie; Badwan, Derar

2018-09-01

The Sensory Tool to Assess Responsiveness (STAR) is an interdisciplinary neurobehavioural diagnostic tool for individuals with prolonged disorders of consciousness. It utilises current diagnostic criteria and is intended to improve upon the high misdiagnosis rate in this population. This study assesses the inter-rater reliability of the STAR and its diagnostic validity in comparison with the Coma Recovery Scale-Revised (CRS-R) and the Wessex Head Injury Matrix (WHIM). Participants were patients with severe acquired brain injury resulting in a disorder of consciousness, who were admitted to the Royal Leamington Spa Rehabilitation Hospital between 1999 and 2009. Patients underwent sensory stimulation sessions during their period of admission, which were recorded on video. Using this footage, patients were re-assessed for this study using the STAR, WHIM and CRS-R criteria. The STAR demonstrated "moderate" inter-rater reliability, "substantial" diagnostic agreement with the CRS-R, and "moderate" agreement with the WHIM. There were no significant differences between diagnoses assigned by the different assessments. The STAR demonstrated a good degree of inter-rater reliability in identification of diagnoses for patients with disorders of consciousness. The diagnostic outcomes of the STAR agreed at a good level with the CRS-R, moderately with the WHIM, and did not significantly differ from either. This demonstrates the reliability and validity of the STAR, showing its appropriateness for clinical use. Future longitudinal studies and research into the STAR's applicability in long-stay rehabilitation are indicated.

Doppler and the Doppler Effect.

DTIC Science & Technology

1984-06-01

that "if the orbital speed of the earth would be ten times its actual value, all fixed stars in the eastern part of the ecliptic would, without...ionosphere by vertical and oblique high-frequency ionospheric soundings. This is illustrated in Figure 1. Over a 24-hour period, signal amplitudes and

Advances in the Dynallax solid-state dynamic parallax barrier autostereoscopic visualization display system.

PubMed

Peterka, Tom; Kooima, Robert L; Sandin, Daniel J; Johnson, Andrew; Leigh, Jason; DeFanti, Thomas A

2008-01-01

A solid-state dynamic parallax barrier autostereoscopic display mitigates some of the restrictions present in static barrier systems, such as fixed view-distance range, slow response to head movements, and fixed stereo operating mode. By dynamically varying barrier parameters in real time, viewers may move closer to the display and move faster laterally than with a static barrier system, and the display can switch between 3D and 2D modes by disabling the barrier on a per-pixel basis. Moreover, Dynallax can output four independent eye channels when two viewers are present, and both head-tracked viewers receive an independent pair of left-eye and right-eye perspective views based on their position in 3D space. The display device is constructed by using a dual-stacked LCD monitor where a dynamic barrier is rendered on the front display and a modulated virtual environment composed of two or four channels is rendered on the rear display. Dynallax was recently demonstrated in a small-scale head-tracked prototype system. This paper summarizes the concepts presented earlier, extends the discussion of various topics, and presents recent improvements to the system.

A novel design of a scanning probe microscope integrated with an ultramicrotome for serial block-face nanotomography

NASA Astrophysics Data System (ADS)

Efimov, Anton E.; Agapov, Igor I.; Agapova, Olga I.; Oleinikov, Vladimir A.; Mezin, Alexey V.; Molinari, Michael; Nabiev, Igor; Mochalov, Konstantin E.

2017-02-01

We present a new concept of a combined scanning probe microscope (SPM)/ultramicrotome apparatus. It enables "slice-and-view" scanning probe nanotomography measurements and 3D reconstruction of the bulk sample nanostructure from series of SPM images after consecutive ultrathin sections. The sample is fixed on a flat XYZ scanning piezostage mounted on the ultramicrotome arm. The SPM measuring head with a cantilever tip and a laser-photodiode tip detection system approaches the sample for SPM measurements of the block-face surface immediately after the ultramicrotome sectioning is performed. The SPM head is moved along guides that are also fixed on the ultramicrotome arm. Thereby, relative dysfunctional displacements of the tip, the sample, and the ultramicrotome knife are minimized. The design of the SPM head enables open frontal optical access to the sample block-face adapted for high-resolution optical lenses for correlative SPM/optical microscopy applications. The new system can be used in a wide range of applications for the study of 3D nanostructures of biological objects, biomaterials, polymer nanocomposites, and nanohybrid materials in various SPM and optical microscopy measuring modes.

Balanced Rotating Spray Tank and Pipe Cleaning and Cleanliness Verification System

NASA Technical Reports Server (NTRS)

Caimi, Raoul E. B. (Inventor); Thaxton, Eric A. (Inventor)

1998-01-01

A system for cleaning and verifying the cleanliness of the interior surfaces of hollow items, such as small bottles, tanks, pipes and tubes, employs a rotating spray head for supplying a gas-liquid cleaning mixture to the item's surface at a supersonic velocity. The spray head incorporates a plurality of nozzles having diverging cross sections so that the incoming gas-liquid mixture is first converged within the spray head and then diverged through the nozzles, thereby accelerating the mixture to a supersonic velocity. In the preferred embodiment, three nozzles are employed; one forwardly facing nozzle at the end of the spray head and two oppositely facing angled nozzles exiting on opposite sides of the spray head which balance each other, and therefore impart no net side load on the spray head. A drive mechanism is provided to rotate the spray head and at the same time move the head back and forth within the item to be cleaned. The drive mechanism acts on a long metal tube to which the spray head is fixed, and thus no moving parts are exposed to the interior surfaces of the items to be cleaned, thereby reducing the risk of contamination.

Pigeons (C. livia) Follow Their Head during Turning Flight: Head Stabilization Underlies the Visual Control of Flight.

PubMed

Ros, Ivo G; Biewener, Andrew A

2017-01-01

Similar flight control principles operate across insect and vertebrate fliers. These principles indicate that robust solutions have evolved to meet complex behavioral challenges. Following from studies of visual and cervical feedback control of flight in insects, we investigate the role of head stabilization in providing feedback cues for controlling turning flight in pigeons. Based on previous observations that the eyes of pigeons remain at relatively fixed orientations within the head during flight, we test potential sensory control inputs derived from head and body movements during 90° aerial turns. We observe that periods of angular head stabilization alternate with rapid head repositioning movements (head saccades), and confirm that control of head motion is decoupled from aerodynamic and inertial forces acting on the bird's continuously rotating body during turning flapping flight. Visual cues inferred from head saccades correlate with changes in flight trajectory; whereas the magnitude of neck bending predicts angular changes in body position. The control of head motion to stabilize a pigeon's gaze may therefore facilitate extraction of important motion cues, in addition to offering mechanisms for controlling body and wing movements. Strong similarities between the sensory flight control of birds and insects may also inspire novel designs of robust controllers for human-engineered autonomous aerial vehicles.

Pigeons (C. livia) Follow Their Head during Turning Flight: Head Stabilization Underlies the Visual Control of Flight

PubMed Central

Ros, Ivo G.; Biewener, Andrew A.

2017-01-01

Similar flight control principles operate across insect and vertebrate fliers. These principles indicate that robust solutions have evolved to meet complex behavioral challenges. Following from studies of visual and cervical feedback control of flight in insects, we investigate the role of head stabilization in providing feedback cues for controlling turning flight in pigeons. Based on previous observations that the eyes of pigeons remain at relatively fixed orientations within the head during flight, we test potential sensory control inputs derived from head and body movements during 90° aerial turns. We observe that periods of angular head stabilization alternate with rapid head repositioning movements (head saccades), and confirm that control of head motion is decoupled from aerodynamic and inertial forces acting on the bird's continuously rotating body during turning flapping flight. Visual cues inferred from head saccades correlate with changes in flight trajectory; whereas the magnitude of neck bending predicts angular changes in body position. The control of head motion to stabilize a pigeon's gaze may therefore facilitate extraction of important motion cues, in addition to offering mechanisms for controlling body and wing movements. Strong similarities between the sensory flight control of birds and insects may also inspire novel designs of robust controllers for human-engineered autonomous aerial vehicles. PMID:29249929

Eye-head coordination during optokinetic stimulation in squirrel monkeys

NASA Technical Reports Server (NTRS)

Kubo, T.; Igarashi, M.; Jensen, D. W.; Homick, J. L.

1981-01-01

Head and eye movements in the yaw plane were recorded during and after optokinetic stimulation in squirrel monkeys. 1) Phasic or tonic head deviations to the side of the ocular quick phase occurred in 94% of total recordings (n = 50) during the perstimulus period, and in 75% of recordings (n = 49) during the poststimulus period. Magnitude of mean head deviation was significantly different between perstimulus and poststimulus periods. 2) Head nystagmus associated with eye nystagmus was consistently observed in seven of nine squirrel monkeys during optokinetic stimulation. Squirrel monkeys are thereby less prone to display head nystagmus than either guinea pigs, pigeons or chickens. 3) Slow phase speeds of coupled head and eye nystagmus were subjected to statistical analysis. A highly significant negative correlation was found between slow phase head and eye speeds. The correlation coefficient was - 0.81 at 60 degrees / sec stimulus (n = 119) and -0.72 at 100 degrees / sec stimulus (n = 131). The gaze speed, calculated by summing the head and eye speeds, was 59.1 plus or minus 6.8 / sec at 60 degrees / sec and 92.2 plus or minus 11.4 at 100 degrees / sec stimulus. There was no significant difference between the gaze speed in a free head condition and the eye speed when the head was fixed.

Pennsylvania Pre-K Counts: End of Year Report, 2009-2010

ERIC Educational Resources Information Center

Pennsylvania Department of Education, 2010

2010-01-01

Pennsylvania Pre-K Counts was created to provide research-based, high quality pre-kindergarten opportunities to at-risk children across the commonwealth by leveraging the existing early education services in schools, Keystone STARS child care programs, Head Start, and licensed nursery schools. The standards are high and the accountability…

NCLB Heads Down Alice's Rabbit Hole

ERIC Educational Resources Information Center

Starnes, Bobby Ann

2005-01-01

This article describes one unconventional elementary school teacher's frustrations with colleagues doubting her competence, intelligence, and sense of purpose as a teacher. In her classroom, she never used textbooks or had a teacher's desk. There were no contests, gold stars, or redbird reading groups. There were no school-supply decorations,…

Angular velocity integration in a fly heading circuit

PubMed Central

Turner-Evans, Daniel; Wegener, Stephanie; Rouault, Hervé; Franconville, Romain; Wolff, Tanya; Seelig, Johannes D; Druckmann, Shaul; Jayaraman, Vivek

2017-01-01

Many animals maintain an internal representation of their heading as they move through their surroundings. Such a compass representation was recently discovered in a neural population in the Drosophila melanogaster central complex, a brain region implicated in spatial navigation. Here, we use two-photon calcium imaging and electrophysiology in head-fixed walking flies to identify a different neural population that conjunctively encodes heading and angular velocity, and is excited selectively by turns in either the clockwise or counterclockwise direction. We show how these mirror-symmetric turn responses combine with the neurons’ connectivity to the compass neurons to create an elegant mechanism for updating the fly’s heading representation when the animal turns in darkness. This mechanism, which employs recurrent loops with an angular shift, bears a resemblance to those proposed in theoretical models for rodent head direction cells. Our results provide a striking example of structure matching function for a broadly relevant computation. DOI: http://dx.doi.org/10.7554/eLife.23496.001 PMID:28530551

Gravity darkening in late-type stars. I. The Coriolis effect

NASA Astrophysics Data System (ADS)

Raynaud, R.; Rieutord, M.; Petitdemange, L.; Gastine, T.; Putigny, B.

2018-02-01

Context. Recent interferometric data have been used to constrain the brightness distribution at the surface of nearby stars, in particular the so-called gravity darkening that makes fast rotating stars brighter at their poles than at their equator. However, good models of gravity darkening are missing for stars that posses a convective envelope. Aim. In order to better understand how rotation affects the heat transfer in stellar convective envelopes, we focus on the heat flux distribution in latitude at the outer surface of numerical models. Methods: We carry out a systematic parameter study of three-dimensional, direct numerical simulations of anelastic convection in rotating spherical shells. As a first step, we neglect the centrifugal acceleration and retain only the Coriolis force. The fluid instability is driven by a fixed entropy drop between the inner and outer boundaries where stress-free boundary conditions are applied for the velocity field. Restricting our investigations to hydrodynamical models with a thermal Prandtl number fixed to unity, we consider both thick and thin (solar-like) shells, and vary the stratification over three orders of magnitude. We measure the heat transfer efficiency in terms of the Nusselt number, defined as the output luminosity normalised by the conductive state luminosity. Results: We report diverse Nusselt number profiles in latitude, ranging from brighter (usually at the onset of convection) to darker equator and uniform profiles. We find that the variations of the surface brightness are mainly controlled by the surface value of the local Rossby number: when the Coriolis force dominates the dynamics, the heat flux is weakened in the equatorial region by the zonal wind and enhanced at the poles by convective motions inside the tangent cylinder. In the presence of a strong background density stratification however, as expected in real stars, the increase of the local Rossby number in the outer layers leads to uniformisation of the surface heat flux distribution.

Halo Histories vs. Galaxy Properties at z=0, III: The Properties of Star-Forming Galaxies

NASA Astrophysics Data System (ADS)

Tinker, Jeremy L.; Hahn, ChangHoon; Mao, Yao-Yuan; Wetzel, Andrew R.

2018-05-01

We measure how the properties of star-forming central galaxies correlate with large-scale environment, δ, measured on 10 h-1Mpc scales. We use galaxy group catalogs to isolate a robust sample of central galaxies with high purity and completeness. The galaxy properties we investigate are star formation rate (SFR), exponential disk scale length Rexp, and Sersic index of the galaxy light profile, nS. We find that, at all stellar masses, there is an inverse correlation between SFR and δ, meaning that above-average star forming centrals live in underdense regions. For nS and Rexp, there is no correlation with δ at M_\\ast ≲ 10^{10.5} M⊙, but at higher masses there are positive correlations; a weak correlation with Rexp and a strong correlation with nS. These data are evidence of assembly bias within the star-forming population. The results for SFR are consistent with a model in which SFR correlates with present-day halo accretion rate, \\dot{M}_h. In this model, galaxies are assigned to halos using the abundance matching ansatz, which maps galaxy stellar mass onto halo mass. At fixed halo mass, SFR is then assigned to galaxies using the same approach, but \\dot{M}_h is used to map onto SFR. The best-fit model requires some scatter in the \\dot{M}_h-SFR relation. The Rexp and nS measurements are consistent with a model in which both of these quantities are correlated with the spin parameter of the halo, λ. Halo spin does not correlate with δ at low halo masses, but for higher mass halos, high-spin halos live in higher density environments at fixed Mh. Put together with the earlier installments of this series, these data demonstrate that quenching processes have limited correlation with halo formation history, but the growth of active galaxies, as well as other detailed galaxies properties, are influenced by the details of halo assembly.

Models of the Cartwheel ring galaxy: Spokes and starbursts

NASA Technical Reports Server (NTRS)

Struck-Marcell, Curtis

1993-01-01

Recent observations of this famous ring galaxy, including optical and near-infrared CCD surface photometry, and VLA radio continuum and 21 cm line mapping (Higdon 1992b, in prep.), have inspired a renewed modeling effort. Toomre's (1978, in The Large-scale Structure of the Universe, eds. Longair and Einasto) series of restricted three-body simulations demonstrated how the multiple rings could be produced in a nearly head-on galaxy collision. New models with a halo-dominated potential based on the 21 cm rotation curve are able to reproduce such details as the spacing between rings, ring widths, offset of the nucleus, and several kinematical features, thus providing strong support for the collisional theory. The new observations have shown there are little or no old stars in Cartwheel; it may consist almost entirely of gas and stars produced as a result of compression in the ring wave. To model this process Smooth Particle Hydrodynamics (SPH) simulations of the Cartwheel disk have been performed. Fixed gravitational potentials were used to represent the Cartwheel and a roughly 30 percent mass collision partner. The interaction dynamics was treated as in the usual restricted three-body approximation, and the effects of local self-gravity between disk particles were calculated. We are particularly interested in testing the theory that enhanced star formation in waves is the result of gravitational instability in the compressed region (see e.g. Kennicutt 1989, ApJ 344, 685). The gas surface density in a number of simulations was initialized to a value slightly below the threshold for local gravitational instability throughout most of the disk. The first ring wave produces relatively modest compressions (a factor of order a few), triggering instability in a narrow range of wavelengths. Self-gravity in the disk is calculated over a comparable range of scales. Simulations were run with isothermal, adiabatic, and adiabatic with radiative cooling characterized by a relatively short timescale. The isothermal approximation is good except in the vicinity of the strong second (inner) ring, and several snapshots from one case are shown in the figure below. Flocculent spiral segments are present before the collision, and these are compressed into dense knots in the ring wave. These knots are likely to be sites of vigorous star formation. In the strong rarefaction behind the outer ring most of the knots are radially stretched and sheared, giving rise to spoke-like features. A few dense knots are evidently very tightly bound, because they retain their coherence and are stretched relatively little through the rarefaction. This is in accord with evidence for continuing star formation in some spokes (Marcum, Appleton and Higdon 1992). The number and spacing of spokes is a direct function of the scale of the gravitational instability in the disk. Thus, the gravitational instability theory, together with the hypothesis that massive stars are only formed in dense knots of gas, can account for most of the distinct morphology of the Cartwheel.

Similar star formation rate and metallicity variability time-scales drive the fundamental metallicity relation

NASA Astrophysics Data System (ADS)

Torrey, Paul; Vogelsberger, Mark; Hernquist, Lars; McKinnon, Ryan; Marinacci, Federico; Simcoe, Robert A.; Springel, Volker; Pillepich, Annalisa; Naiman, Jill; Pakmor, Rüdiger; Weinberger, Rainer; Nelson, Dylan; Genel, Shy

2018-06-01

The fundamental metallicity relation (FMR) is a postulated correlation between galaxy stellar mass, star formation rate (SFR), and gas-phase metallicity. At its core, this relation posits that offsets from the mass-metallicity relation (MZR) at a fixed stellar mass are correlated with galactic SFR. In this Letter, we use hydrodynamical simulations to quantify the time-scales over which populations of galaxies oscillate about the average SFR and metallicity values at fixed stellar mass. We find that Illustris and IllustrisTNG predict that galaxy offsets from the star formation main sequence and MZR oscillate over similar time-scales, are often anticorrelated in their evolution, evolve with the halo dynamical time, and produce a pronounced FMR. Our models indicate that galaxies oscillate about equilibrium SFR and metallicity values - set by the galaxy's stellar mass - and that SFR and metallicity offsets evolve in an anticorrelated fashion. This anticorrelated variability of the metallicity and SFR offsets drives the existence of the FMR in our models. In contrast to Illustris and IllustrisTNG, we speculate that the SFR and metallicity evolution tracks may become decoupled in galaxy formation models dominated by feedback-driven globally bursty SFR histories, which could weaken the FMR residual correlation strength. This opens the possibility of discriminating between bursty and non-bursty feedback models based on the strength and persistence of the FMR - especially at high redshift.

STAR FORMATION IN THE MOLECULAR CLOUD ASSOCIATED WITH THE MONKEY HEAD NEBULA: SEQUENTIAL OR SPONTANEOUS?

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

Chibueze, James O.; Imura, Kenji; Omodaka, Toshihiro

2013-01-01

We mapped the (1,1), (2,2), and (3,3) lines of NH{sub 3} toward the molecular cloud associated with the Monkey Head Nebula (MHN) with a 1.'6 angular resolution using a Kashima 34 m telescope operated by the National Institute of Information and Communications Technology (NICT). The kinetic temperature of the molecular gas is 15-30 K in the eastern part and 30-50 K in the western part. The warmer gas is confined to a small region close to the compact H II region S252A. The cooler gas is extended over the cloud even near the extended H II region, the MHN. Wemore » made radio continuum observations at 8.4 GHz using the Yamaguchi 32 m radio telescope. The resultant map shows no significant extension from the H{alpha} image. This means that the molecular cloud is less affected by the MHN, suggesting that the molecular cloud did not form by the expanding shock of the MHN. Although the spatial distribution of the Wide-field Infrared Survey Explorer and Two Micron All Sky Survey point sources suggests that triggered low- and intermediate-mass star formation took place locally around S252A, but the exciting star associated with it should be formed spontaneously in the molecular cloud.« less

[Simulated used of the "grasping tie" as in esophago-jejunostomy after total gastrectomy].

PubMed

Picardi, Nicola

2003-01-01

Simulated test of effectiveness of the original tool grasping tie--technically already illustrated in a former paper listed in bibliography--for fixing a spongy rubber tube simulating an oesophagus on a circular stapler head axis, by tightening over it a nylon ribbon slip-knot (the tie). After connecting the head to the stapler anvil through an other spongy rubber tube simulating a jejunal loop, and the firing of the stapler, it is demonstrated the correct circular anastomosis achievable.

Large-Scale Structure of the Carina Nebula.

PubMed

Smith; Egan; Carey; Price; Morse; Price

2000-04-01

Observations obtained with the Midcourse Space Experiment (MSX) satellite reveal for the first time the complex mid-infrared morphology of the entire Carina Nebula (NGC 3372). On the largest size scale of approximately 100 pc, the thermal infrared emission from the giant H ii region delineates one coherent structure: a (somewhat distorted) bipolar nebula with the major axis perpendicular to the Galactic plane. The Carina Nebula is usually described as an evolved H ii region that is no longer actively forming stars, clearing away the last vestiges of its natal molecular cloud. However, the MSX observations presented here reveal numerous embedded infrared sources that are good candidates for sites of current star formation. Several compact infrared sources are located at the heads of dust pillars or in dark globules behind ionization fronts. Because their morphology suggests a strong interaction with the peculiar collection of massive stars in the nebula, we speculate that these new infrared sources may be sites of triggered star formation in NGC 3372.

The Pan-STARRS1 medium-deep survey: The role of galaxy group environment in the star formation rate versus stellar mass relation and quiescent fraction out to z ∼ 0.8

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

Lin, Lihwai; Chen, Chin-Wei; Coupon, Jean

2014-02-10

Using a large optically selected sample of field and group galaxies drawn from the Pan-STARRS1 Medium-Deep Survey (PS1/MDS), we present a detailed analysis of the specific star formation rate (SSFR)—stellar mass (M {sub *}) relation, as well as the quiescent fraction versus M {sub *} relation in different environments. While both the SSFR and the quiescent fraction depend strongly on stellar mass, the environment also plays an important role. Using this large galaxy sample, we confirm that the fraction of quiescent galaxies is strongly dependent on environment at a fixed stellar mass, but that the amplitude and the slope ofmore » the star-forming sequence is similar between the field and groups: in other words, the SSFR-density relation at a fixed stellar mass is primarily driven by the change in the star-forming and quiescent fractions between different environments rather than a global suppression in the star formation rate for the star-forming population. However, when we restrict our sample to the cluster-scale environments (M > 10{sup 14} M {sub ☉}), we find a global reduction in the SSFR of the star-forming sequence of 17% at 4σ confidence as opposed to its field counterpart. After removing the stellar mass dependence of the quiescent fraction seen in field galaxies, the excess in the quiescent fraction due to the environment quenching in groups and clusters is found to increase with stellar mass, although deeper and larger data from the full PS1/MDS will be required to draw firm conclusions. We argue that these results are in favor of galaxy mergers to be the primary environment quenching mechanism operating in galaxy groups whereas strangulation is able to reproduce the observed trend in the environment quenching efficiency and stellar mass relation seen in clusters. Our results also suggest that the relative importance between mass quenching and environment quenching depends on stellar mass—the mass quenching plays a dominant role in producing quiescent galaxies for more massive galaxies, while less massive galaxies are quenched mostly through the environmental effect, with the transition mass around 1-2 × 10{sup 10} M {sub ☉} in the group/cluster environment.« less

Single wrench separates nuts from free-floating bolts

NASA Technical Reports Server (NTRS)

Thompson, C.

1967-01-01

Pneumatic impact wrench removes the nuts from freely turning bolts when the heads cannot be reached or the shafts anchored. It uses a fixed screwdriver blade that fits a slot cut into the threaded end of the bolt shaft.

Stabilization of gaze during circular locomotion in light. I. Compensatory head and eye nystagmus in the running monkey

NASA Technical Reports Server (NTRS)

Solomon, D.; Cohen, B.

1992-01-01

1. A rhesus and cynomolgus monkey were trained to run around the perimeter of a circular platform in light. We call this "circular locomotion" because forward motion had an angular component. Head and body velocity in space were recorded with angular rate sensors and eye movements with electrooculography (EOG). From these measurements we derived signals related to the angular velocity of the eyes in the head (Eh), of the head on the body (Hb), of gaze on the body (Gb), of the body in space (Bs), of gaze in space (Gs), and of the gain of gaze (Gb/Bs). 2. The monkeys had continuous compensatory nystagmus of the head and eyes while running, which stabilized Gs during the slow phases. The eyes established and maintained compensatory gaze velocities at the beginning and end of the slow phases. The head contributed to gaze velocity during the middle of the slow phases. Slow phase Gb was as high as 250 degrees/s, and targets were fixed for gaze angles as large as 90-140 degrees. 3. Properties of the visual surround affected both the gain and strategy of gaze compensation in the one monkey tested. Gains of Eh ranged from 0.3 to 1.1 during compensatory gaze nystagmus. Gains of Hb varied around 0.3 (0.2-0.7), building to a maximum as Eh dropped while running past sectors of interest. Consistent with predictions, gaze gains varied from below to above unity, when translational and angular body movements with regard to the target were in opposite or the same directions, respectively. 4. Gaze moved in saccadic shifts in the direction of running during quick phases. Most head quick phases were small, and at times the head only paused during an eye quick phase. Eye quick phases were larger, ranging up to 60 degrees. This is larger than quick phases during passive rotation or saccades made with the head fixed. 5. These data indicate that head and eye nystagmus are natural phenomena that support gaze compensation during locomotion. Despite differential utilization of the head and eyes in various conditions, Gb compensated for Bs. There are various frames of reference in which an estimate of angular velocity that drives the head and eyes could be based. We infer that body in space velocity (Bs) is likely to be represented centrally to provide this signal.

The FMOS-COSMOS survey of star-forming galaxies at z ∼ 1.6. II. The mass-metallicity relation and the dependence on star formation rate and dust extinction

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

Zahid, H. J.; Sanders, D. B.; Chu, J.

We investigate the relationships between stellar mass, gas-phase oxygen abundance (metallicity), star formation rate (SFR), and dust content of star-forming galaxies at z ∼ 1.6 using Subaru/FMOS spectroscopy in the COSMOS field. The mass-metallicity (MZ) relation at z ∼ 1.6 is steeper than the relation observed in the local universe. The steeper MZ relation at z ∼ 1.6 is mainly due to evolution in the stellar mass where the MZ relation begins to turnover and flatten. This turnover mass is 1.2 dex larger at z ∼ 1.6. The most massive galaxies at z ∼ 1.6 (∼10{sup 11} M {sub ☉})more » are enriched to the level observed in massive galaxies in the local universe. The MZ relation we measure at z ∼ 1.6 supports the suggestion of an empirical upper metallicity limit that does not significantly evolve with redshift. We find an anti-correlation between metallicity and SFR for galaxies at a fixed stellar mass at z ∼ 1.6, which is similar to trends observed in the local universe. We do not find a relation between stellar mass, metallicity, and SFR that is independent of redshift; rather, our data suggest that there is redshift evolution in this relation. We examine the relation between stellar mass, metallicity, and dust extinction, and find that at a fixed stellar mass, dustier galaxies tend to be more metal rich. From examination of the stellar masses, metallicities, SFRs, and dust extinctions, we conclude that stellar mass is most closely related to dust extinction.« less

Association between vestibulo-ocular reflex suppression, balance, gait, and fall risk in ageing and neurodegenerative disease: protocol of a one-year prospective follow-up study.

PubMed

Srulijes, Karin; Mack, David J; Klenk, Jochen; Schwickert, Lars; Ihlen, Espen A F; Schwenk, Michael; Lindemann, Ulrich; Meyer, Miriam; Srijana, K C; Hobert, Markus A; Brockmann, Kathrin; Wurster, Isabel; Pomper, Jörn K; Synofzik, Matthis; Schneider, Erich; Ilg, Uwe; Berg, Daniela; Maetzler, Walter; Becker, Clemens

2015-10-09

Falls frequency increases with age and particularly in neurogeriatric cohorts. The interplay between eye movements and locomotion may contribute substantially to the occurrence of falls, but is hardly investigated. This paper provides an overview of current approaches to simultaneously measure eye and body movements, particularly for analyzing the association of vestibulo-ocular reflex (VOR) suppression, postural deficits and falls in neurogeriatric risk cohorts. Moreover, VOR suppression is measured during head-fixed target presentation and during gaze shifting while postural control is challenged. Using these approaches, we aim at identifying quantitative parameters of eye-head-coordination during postural balance and gait, as indicators of fall risk. Patients with Progressive Supranuclear Palsy (PSP) or Parkinson's disease (PD), age- and sex-matched healthy older adults, and a cohort of young healthy adults will be recruited. Baseline assessment will include a detailed clinical assessment, covering medical history, neurological examination, disease specific clinical rating scales, falls-related self-efficacy, activities of daily living, neuro-psychological screening, assessment of mobility function and a questionnaire for retrospective falls. Moreover, participants will simultaneously perform eye and head movements (fixating a head-fixed target vs. shifting gaze to light emitting diodes in order to quantify vestibulo-ocular reflex suppression ability) under different conditions (sitting, standing, or walking). An eye/head tracker synchronized with a 3-D motion analysis system will be used to quantify parameters related to eye-head-coordination, postural balance, and gait. Established outcome parameters related to VOR suppression ability (e.g., gain, saccadic reaction time, frequency of saccades) and motor related fall risk (e.g., step-time variability, postural sway) will be calculated. Falls will be assessed prospectively over 12 months via protocols and monthly telephone interviews. This study protocol describes an experimental setup allowing the analysis of simultaneously assessed eye, head and body movements. Results will improve our understanding of the influence of the interplay between eye, head and body movements on falls in geriatric high-risk cohorts.

Experimental support that ocular tremor in Parkinson's disease does not originate from head movement.

PubMed

Gitchel, George T; Wetzel, Paul A; Qutubuddin, Abu; Baron, Mark S

2014-07-01

Our recent report of ocular tremor in Parkinson's disease (PD) has raised considerable controversy as to the origin of the tremor. Using an infrared based eye tracker and a magnetic head tracker, we reported that ocular tremor was recordable in PD subjects with no apparent head tremor. However, other investigators suggest that the ocular tremor may represent either transmitted appendicular tremor or subclinical head tremor inducing the vestibulo-ocular reflex (VOR). The present study aimed to further investigate the origin of ocular tremor in PD. Eye movements were recorded in 8 PD subjects both head free, and with full head restraint by means of a head holding device and a dental impression bite plate. Head movements were recorded independently using both a high sensitivity tri-axial accelerometer and a magnetic tracking system, each synchronized to the eye tracker. Ocular tremor was observed in all 8 PD subjects and was not influenced by head free and head fixed conditions. Both magnetic tracking and accelerometer recordings supported that the ocular tremor was fully independent of head position. The present study findings support our initial findings that ocular tremor is a fundamental feature of PD unrelated to head movements. Although the utility of ocular tremor for diagnostic purposes requires validation, current findings in large cohorts of PD subjects suggest its potential as a reliable clinical biomarker. Published by Elsevier Ltd.

Design challenges and coordination issues in hotel projects

NASA Astrophysics Data System (ADS)

Saunders, Melvin L., IV; Marsh, David

2002-11-01

The design of a Five Star hotel facility encompasses a myriad of design dilemmas. On the same note, the design of a One Star or Two Star hotel has many dilemmas of its own. The ability of an acoustical consultant, as an integral part of the design team, to recognize the differences between these types of projects can be the difference between a successful hotel project and miserable failure. Different quality hotels require different levels of design criteria. Proper coordination and timing between trades and installations, such as loudspeakers, ceiling coffers, chandeliers, sprinkler heads, and ductwork, is also very important for the success of the overall project. This paper will discuss techniques and methods to produce successful hotel projects, as well as various noise sources throughout these spaces. It will also highlight a number of tips learned through many hotel design experiences.

KSC-2011-1890

NASA Image and Video Library

2011-02-28

CAPE CANAVERAL, Fla. -- The Solid Rocket Booster Retrieval Ship Freedom Star leaves the dock at Hangar AF at Cape Canaveral Air Force Station and heads back to its home base at the Turn Basin at NASA's Kennedy Space Center in Florida. The ship recently retrieved a booster that was used during space shuttle Discovery's STS-133 launch from Kennedy's Launch Pad 39A on Feb. 24. The shuttle’s two solid rocket booster casings and associated flight hardware are recovered in the Atlantic Ocean after every launch by Liberty Star and Freedom Star. The boosters impact the Atlantic about seven minutes after liftoff and the retrieval ships are stationed about 10 miles from the impact area at the time of splashdown. After the spent segments are processed, they will be transported to Utah, where they will be refurbished and stored, if needed. Photo credit: NASA/Jim Grossmann

Internal ballistics model update for ASRM dome

NASA Technical Reports Server (NTRS)

Bowden, Mark H.; Jenkins, Billy Z.

1991-01-01

A previous report (no. 5-32279, contract NAS8-36955, DO 51) describes the measures taken to adapt the NASA Complex Burning Region Model and code so that is was applicable to the Advanced Solid Rocket Motor as envisioned at that time. The code so modified was called the CBRM-A. CBRM-A could calculate the port volume and burning area for the star, transition, and cylindrically perforated regions of the motor. Described here is a subsequent effort to add computation of port volume and burning area for the Advanced Solid Rocket Motor head dome. Sample output, input, and overview of the models are included. The software was configured in two forms - a stand alone head dome code and a code integrating the head dome solution with the CBRM-A.

Star-forming galaxies are predicted to lie on a fundamental plane of mass, star formation rate and α-enhancement

NASA Astrophysics Data System (ADS)

Matthee, Jorryt; Schaye, Joop

2018-05-01

Observations show that star-forming galaxies reside on a tight three-dimensional plane between mass, gas-phase metallicity and star formation rate (SFR), which can be explained by the interplay between metal-poor gas inflows, SFR and outflows. However, different metals are released on different time-scales, which may affect the slope of this relation. Here, we use central, star-forming galaxies with Mstar = 109.0 - 10.5 M⊙ from the EAGLE hydrodynamical simulation to examine three-dimensional relations between mass, SFR and chemical enrichment using absolute and relative C, N, O and Fe abundances. We show that the scatter is smaller when gas-phase α-enhancement is used rather than metallicity. A similar plane also exists for stellar α-enhancement, implying that present-day specific SFRs are correlated with long time-scale star formation histories. Between z = 0 and 1, the α-enhancement plane is even more insensitive to redshift than the plane using metallicity. However, it evolves at z > 1 due to lagging iron yields. At fixed mass, galaxies with higher SFRs have star formation histories shifted toward late times, are more α-enhanced and this α-enhancement increases with redshift as observed. These findings suggest that relations between physical properties inferred from observations may be affected by systematic variations in α-enhancements.

Compact and mobile high resolution PET brain imager

DOEpatents

Majewski, Stanislaw [Yorktown, VA; Proffitt, James [Newport News, VA

2011-02-08

A brain imager includes a compact ring-like static PET imager mounted in a helmet-like structure. When attached to a patient's head, the helmet-like brain imager maintains the relative head-to-imager geometry fixed through the whole imaging procedure. The brain imaging helmet contains radiation sensors and minimal front-end electronics. A flexible mechanical suspension/harness system supports the weight of the helmet thereby allowing for patient to have limited movements of the head during imaging scans. The compact ring-like PET imager enables very high resolution imaging of neurological brain functions, cancer, and effects of trauma using a rather simple mobile scanner with limited space needs for use and storage.

Externally fed star formation: a numerical study

NASA Astrophysics Data System (ADS)

Mohammadpour, Motahareh; Stahler, Steven W.

2013-08-01

We investigate, through a series of numerical calculations, the evolution of dense cores that are accreting external gas up to and beyond the point of star formation. Our model clouds are spherical, unmagnetized configurations with fixed outer boundaries, across which gas enters subsonically. When we start with any near-equilibrium state, we find that the cloud's internal velocity also remains subsonic for an extended period, in agreement with observations. However, the velocity becomes supersonic shortly before the star forms. Consequently, the accretion rate building up the protostar is much greater than the benchmark value c_s^3/G, where cs is the sound speed in the dense core. This accretion spike would generate a higher luminosity than those seen in even the most embedded young stars. Moreover, we find that the region of supersonic infall surrounding the protostar races out to engulf much of the cloud, again in violation of the observations, which show infall to be spatially confined. Similar problematic results have been obtained by all other hydrodynamic simulations to date, regardless of the specific infall geometry or boundary conditions adopted. Low-mass star formation is evidently a quasi-static process, in which cloud gas moves inward subsonically until the birth of the star itself. We speculate that magnetic tension in the cloud's deep interior helps restrain the infall prior to this event.

Prognostic Modeling and Experimental Techniques for Electrolytic Capacitor Health Monitoring

DTIC Science & Technology

2011-09-01

result in errors in the Inertial Navigation ( INAV ) computations of position and heading, causing the aircraft to fly off course [2, 3]. Chetan... Science Instruments, 2010. 21) IEC 60384-4-1 Fixed capacitors for use in electronic equipment

Competitions: What Parents of Gifted Students Must Know

ERIC Educational Resources Information Center

Karnes, Frances A.; Riley, Tracy L.

2005-01-01

The media calls them the wizards of tomorrow, the fix-it-kids, athletes of the mind, star players, and champs. These are the young people who compete and win academic, artistic, leadership, and service related competitions. Competitors spell words as difficult as autochthonous, make new scientific discoveries, compose poetry, publish their short…

Reviews Book: Nucleus Book: The Wonderful World of Relativity Book: Head Shot Book: Cosmos Close-Up Places to Visit: Physics DemoLab Book: Quarks, Leptons and the Big Bang EBook: Shooting Stars Equipment: Victor 70C USB Digital Multimeter Web Watch

NASA Astrophysics Data System (ADS)

2012-09-01

WE RECOMMEND Nucleus: A Trip into the Heart of Matter A coffee-table book for everyone to dip into and learn from The Wonderful World of Relativity A charming, stand-out introduction to relativity The Physics DemoLab, National University of Singapore A treasure trove of physics for hands-on science experiences Quarks, Leptons and the Big Bang Perfect to polish up on particle physics for older students Victor 70C USB Digital Multimeter Equipment impresses for usability and value WORTH A LOOK Cosmos Close-Up Weighty tour of the galaxy that would make a good display Shooting Stars Encourage students to try astrophotography with this ebook HANDLE WITH CARE Head Shot: The Science Behind the JKF Assassination Exploration of the science behind the crime fails to impress WEB WATCH App-lied science for education: a selection of free Android apps are reviewed and iPhone app options are listed

Keeping it simple: studying grammatical encoding with lexically reduced item sets

PubMed Central

Veenstra, Alma; Acheson, Daniel J.; Meyer, Antje S.

2014-01-01

Compared to the large body of work on lexical access, little research has been done on grammatical encoding in language production. An exception is the generation of subject-verb agreement. Here, two key findings have been reported: (1) speakers make more agreement errors when the head and local noun of a phrase mismatch in number than when they match [e.g., the key to the cabinet(s)]; and (2) this attraction effect is asymmetric, with stronger attraction for singular than for plural head nouns. Although these findings are robust, the cognitive processes leading to agreement errors and their significance for the generation of correct agreement are not fully understood. We propose that future studies of agreement, and grammatical encoding in general, may benefit from using paradigms that tightly control the variability of the lexical content of the material. We report two experiments illustrating this approach. In both of them, the experimental items featured combinations of four nouns, four color adjectives, and two prepositions. In Experiment 1, native speakers of Dutch described pictures in sentences such as the circle next to the stars is blue. In Experiment 2, they carried out a forced-choice task, where they read subject noun phrases (e.g., the circle next to the stars) and selected the correct verb-phrase (is blue or are blue) with a button press. Both experiments showed an attraction effect, with more errors after subject phrases with mismatching, compared to matching head and local nouns. This effect was stronger for singular than plural heads, replicating the attraction asymmetry. In contrast, the response times recorded in Experiment 2 showed similar attraction effects for singular and plural head nouns. These results demonstrate that critical agreement phenomena can be elicited reliably in lexically reduced contexts. We discuss the theoretical implications of the findings and the potential and limitations of studies using lexically simple materials. PMID:25101039

Keeping it simple: studying grammatical encoding with lexically reduced item sets.

PubMed

Veenstra, Alma; Acheson, Daniel J; Meyer, Antje S

2014-01-01

Compared to the large body of work on lexical access, little research has been done on grammatical encoding in language production. An exception is the generation of subject-verb agreement. Here, two key findings have been reported: (1) speakers make more agreement errors when the head and local noun of a phrase mismatch in number than when they match [e.g., the key to the cabinet(s)]; and (2) this attraction effect is asymmetric, with stronger attraction for singular than for plural head nouns. Although these findings are robust, the cognitive processes leading to agreement errors and their significance for the generation of correct agreement are not fully understood. We propose that future studies of agreement, and grammatical encoding in general, may benefit from using paradigms that tightly control the variability of the lexical content of the material. We report two experiments illustrating this approach. In both of them, the experimental items featured combinations of four nouns, four color adjectives, and two prepositions. In Experiment 1, native speakers of Dutch described pictures in sentences such as the circle next to the stars is blue. In Experiment 2, they carried out a forced-choice task, where they read subject noun phrases (e.g., the circle next to the stars) and selected the correct verb-phrase (is blue or are blue) with a button press. Both experiments showed an attraction effect, with more errors after subject phrases with mismatching, compared to matching head and local nouns. This effect was stronger for singular than plural heads, replicating the attraction asymmetry. In contrast, the response times recorded in Experiment 2 showed similar attraction effects for singular and plural head nouns. These results demonstrate that critical agreement phenomena can be elicited reliably in lexically reduced contexts. We discuss the theoretical implications of the findings and the potential and limitations of studies using lexically simple materials.

The cosmic MeV neutrino background as a laboratory for black hole formation

NASA Astrophysics Data System (ADS)

Yüksel, Hasan; Kistler, Matthew D.

2015-12-01

Calculations of the cosmic rate of core collapses, and the associated neutrino flux, commonly assume that a fixed fraction of massive stars collapse to black holes. We argue that recent results suggest that this fraction instead increases with redshift. With relatively more stars vanishing as ;unnovae; in the distant universe, the detectability of the cosmic MeV neutrino background is improved due to their hotter neutrino spectrum, and expectations for supernova surveys are reduced. We conclude that neutrino detectors, after the flux from normal SNe is isolated via either improved modeling or the next Galactic SN, can probe the conditions and history of black hole formation.

Externally Induced Evaporation of Young Stellar Disks: The Case for HST 10 in Orion's Trapezium.

NASA Astrophysics Data System (ADS)

Johnstone, D.; Hollenbach, D.; Storzer, H.; Bally, J.; Sutherland, R.

1996-12-01

The Trapezium region in Orion is composed of a few high-mass stars, responsible for the ionization of the surrounding gas, and a plethora of low-mass stars with disks. Observations at infrared, optical, and radio wavelengths have led to the discovery of extended ionized envelopes around many of the young low-mass stars requiring evaporation rates dot M ~ 10(-7) Modot/yr. In this poster we explain these observations through a model for the evaporation of disks around young low-mass stars by an external source of high energy photons. In particular, the externally produced ultraviolet continuum longward of the Lyman limit is used to heat the disk surface and produce a warm neutral flow. The model results in an offset ionization front, where the neutral flow encounters Lyman continuum radiation, and a mass-loss rate which is fixed due to the self-regulating nature of FUV heating. Applying this model to the Trapezium region evaporating objects, particularly HST 10, produces a satisfactory solution to both the mass-loss rate and the size of the ionized envelopes. The resulting short destruction times for these disks constrain the gestation period for planet embryos around stars in dense clusters.

How good a clock is rotation? The stellar rotation-mass-age relationship for old field stars

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

Epstein, Courtney R.; Pinsonneault, Marc H., E-mail: epstein@astronomy.ohio-state.edu, E-mail: pinsono@astronomy.ohio-state.edu

2014-01-10

The rotation-mass-age relationship offers a promising avenue for measuring the ages of field stars, assuming the attendant uncertainties to this technique can be well characterized. We model stellar angular momentum evolution starting with a rotation distribution from open cluster M37. Our predicted rotation-mass-age relationship shows significant zero-point offsets compared to an alternative angular momentum loss law and published gyrochronology relations. Systematic errors at the 30% level are permitted by current data, highlighting the need for empirical guidance. We identify two fundamental sources of uncertainty that limit the precision of rotation-based ages and quantify their impact. Stars are born with amore » range of rotation rates, which leads to an age range at fixed rotation period. We find that the inherent ambiguity from the initial conditions is important for all young stars, and remains large for old stars below 0.6 M {sub ☉}. Latitudinal surface differential rotation also introduces a minimum uncertainty into rotation period measurements and, by extension, rotation-based ages. Both models and the data from binary star systems 61 Cyg and α Cen demonstrate that latitudinal differential rotation is the limiting factor for rotation-based age precision among old field stars, inducing uncertainties at the ∼2 Gyr level. We also examine the relationship between variability amplitude, rotation period, and age. Existing ground-based surveys can detect field populations with ages as old as 1-2 Gyr, while space missions can detect stars as old as the Galactic disk. In comparison with other techniques for measuring the ages of lower main sequence stars, including geometric parallax and asteroseismology, rotation-based ages have the potential to be the most precise chronometer for 0.6-1.0 M {sub ☉} stars.« less

Design and CFD analysis of intake port and exhaust port for a 4 valve cylinder head engine

NASA Astrophysics Data System (ADS)

Latheesh, V. M.; Parthasarathy, P.; Baskaran, V.; Karthikeyan, S.

2018-02-01

In cylinder air motion in a compression ignition engine effects mixing of air-fuel, quality of combustion and emission produced. The primary objective is to design and analyze intake and the exhaust port for a four valve cylinder head to meet higher emission norms for a given diesel engine with two valves. In this work, an existing cylinder head designed for two valves was redesigned with 4 valves. The modern trend also confirms this approach. This is being followed in the design and development of new generation engines to meet the stringent environment norms, competition in market and demand for more fuel-efficient engines. The swirl ratio and flow coefficient were measured for different valve lifts using STAR CCM+. CFD results were validated with the two-valve cylinder experimental results. After validation, a comparison between two-valve and four-valve cylinder head was done. The conversion of two valve cylinder head to 4 valves may not support modern high swirl generating port layout and requires a trade-off between many design parameters.

Virtual head rotation reveals a process of route reconstruction from human vestibular signals

PubMed Central

Day, Brian L; Fitzpatrick, Richard C

2005-01-01

The vestibular organs can feed perceptual processes that build a picture of our route as we move about in the world. However, raw vestibular signals do not define the path taken because, during travel, the head can undergo accelerations unrelated to the route and also be orientated in any direction to vary the signal. This study investigated the computational process by which the brain transforms raw vestibular signals for the purpose of route reconstruction. We electrically stimulated the vestibular nerves of human subjects to evoke a virtual head rotation fixed in skull co-ordinates and measure its perceptual effect. The virtual head rotation caused subjects to perceive an illusory whole-body rotation that was a cyclic function of head-pitch angle. They perceived whole-body yaw rotation in one direction with the head pitched forwards, the opposite direction with the head pitched backwards, and no rotation with the head in an intermediate position. A model based on vector operations and the anatomy and firing properties of semicircular canals precisely predicted these perceptions. In effect, a neural process computes the vector dot product between the craniocentric vestibular vector of head rotation and the gravitational unit vector. This computation yields the signal of body rotation in the horizontal plane that feeds our perception of the route travelled. PMID:16002439

Head movements encode emotions during speech and song.

PubMed

Livingstone, Steven R; Palmer, Caroline

2016-04-01

When speaking or singing, vocalists often move their heads in an expressive fashion, yet the influence of emotion on vocalists' head motion is unknown. Using a comparative speech/song task, we examined whether vocalists' intended emotions influence head movements and whether those movements influence the perceived emotion. In Experiment 1, vocalists were recorded with motion capture while speaking and singing each statement with different emotional intentions (very happy, happy, neutral, sad, very sad). Functional data analyses showed that head movements differed in translational and rotational displacement across emotional intentions, yet were similar across speech and song, transcending differences in F0 (varied freely in speech, fixed in song) and lexical variability. Head motion specific to emotional state occurred before and after vocalizations, as well as during sound production, confirming that some aspects of movement were not simply a by-product of sound production. In Experiment 2, observers accurately identified vocalists' intended emotion on the basis of silent, face-occluded videos of head movements during speech and song. These results provide the first evidence that head movements encode a vocalist's emotional intent and that observers decode emotional information from these movements. We discuss implications for models of head motion during vocalizations and applied outcomes in social robotics and automated emotion recognition. (c) 2016 APA, all rights reserved).

Measuring mandibular motions

NASA Technical Reports Server (NTRS)

Dimeff, J.; Rositano, S.; Taylor, R. C.

1977-01-01

Mandibular motion along three axes is measured by three motion transducers on floating yoke that rests against mandible. System includes electronics to provide variety of outputs for data display and processing. Head frame is strapped to test subject's skull to provide fixed point of reference for transducers.

29 CFR 1910.27 - Fixed ladders.

Code of Federal Regulations, 2014 CFR

2014-07-01

... unbroken length of 30 feet. EC27OC91.005 Figure D-5—Deflector Plates for Head Hazards EC27OC91.006 Figure D.... Vertical bars shall be located at a maximum spacing of 40 degrees around the circumference of the cage...

29 CFR 1910.27 - Fixed ladders.

Code of Federal Regulations, 2011 CFR

2011-07-01

... unbroken length of 30 feet. EC27OC91.005 Figure D-5—Deflector Plates for Head Hazards EC27OC91.006 Figure D.... Vertical bars shall be located at a maximum spacing of 40 degrees around the circumference of the cage...

29 CFR 1910.27 - Fixed ladders.

Code of Federal Regulations, 2013 CFR

2013-07-01

... unbroken length of 30 feet. EC27OC91.005 Figure D-5—Deflector Plates for Head Hazards EC27OC91.006 Figure D.... Vertical bars shall be located at a maximum spacing of 40 degrees around the circumference of the cage...

Smart optical writing head design for laser-based manufacturing

NASA Astrophysics Data System (ADS)

Amin, M. Junaid; Riza, Nabeel A.

2014-03-01

Proposed is a smart optical writing head design suitable for high precision industrial laser based machining and manufacturing applications. The design uses an Electronically Controlled Variable Focus Lens (ECVFL) which enables the highest achievable spatial resolution of writing head spot sizes for axial target distances reaching 8 meters. A proof-of-concept experiment is conducted using a visible wavelength laser with a collimated beam that is coupled to beam conditioning optics which includes an electromagnetically actuated deformable membrane liquid ECVFL cascaded with a bias convex lens of fixed focal length. Electronic tuning and control of the ECVFL keeps the laser writing head far-field spot beam radii under 1 mm that is demonstrated over a target range of 20 cm to 800 cm. Applications for the proposed writing head design, which can accommodate both continuous wave and pulsed wave sources, include laser machining, high precision industrial molding of components, as well as materials processing requiring material sensitive optical power density control.

Effect of external viscous load on head movement

NASA Technical Reports Server (NTRS)

Nam, M.-H.; Lakshminarayanan, V.; Stark, L. W.

1984-01-01

Quantitative measurements of horizontal head rotation were obtained from normal human subjects intending to make 'time optimal' trajectories between targets. By mounting large, lightweight vanes on the head, viscous damping B, up to 15 times normal could be added to the usual mechanical load of the head. With the added viscosity, the head trajectory was slowed and of larger duration (as expected) since fixed and maximal (for that amplitude) muscle forces had to accelerate the added viscous load. This decreased acceleration and velocity and longer duration movement still ensued in spite of adaptive compensation; this provided evidence that quasi-'time optimal' movements do indeed employ maximal muscle forces. The adaptation to this added load was rapid. Then the 'adapted state' subjects produced changed trajectories. The adaptation depended in part on the differing detailed instructions given to the subjects. This differential adaptation provided evidence for the existence of preprogrammed controller signals, sensitive to intended criterion, and neurologically ballistic or open loop rather than modified by feedback from proprioceptors or vision.

Translation and Rotation Trade Off in Human Visual Heading Estimation

NASA Technical Reports Server (NTRS)

Stone, Leland S.; Perrone, John A.; Null, Cynthia H. (Technical Monitor)

1996-01-01

We have previously shown that, during simulated curvilinear motion, humans can make reasonably accurate and precise heading judgments from optic flow without either oculomotor or static-depth cues about rotation. We now systematically investigate the effect of varying the parameters of self-motion. We visually simulated 400 ms of self-motion along curved paths (constant rotation and translation rates, fixed retinocentric heading) towards two planes of random dots at 10.3 m and 22.3 m at mid-trial. Retinocentric heading judgments of 4 observers (2 naive) were measured for 12 different combinations of translation (T between 4 and 16 m/s) and rotation (R either 8 or 16 deg/s). In the range tested, heading bias and uncertainty decrease quasilinearly with T/R, but the bias also appears to depend on R. If depth is held constant, the ratio T/R can account for much of the variation in the accuracy and precision of human visual heading estimation, although further experiments are needed to resolve whether absolute rotation rate, total flow rate, or some other factor can account for the observed -2 deg shift between the bias curves.

Micro-drive and headgear for chronic implant and recovery of optoelectronic probes.

PubMed

Chung, Jinho; Sharif, Farnaz; Jung, Dajung; Kim, Soyoun; Royer, Sebastien

2017-06-05

Silicon probes are multisite electrodes used for the electrophysiological recording of large neuronal ensembles. Optoelectronic probes (OEPs) are recent upgrades that allow, in parallel, the delivery of local optical stimuli. The procedures to use these delicate electrodes for chronic experiments in mice are still underdeveloped and typically assume one-time uses. Here, we developed a micro-drive, a support for OEPs optical fibers, and a hat enclosure, which fabrications consist in fitting and fastening together plastic parts made with 3D printers. Excluding two parts, all components and electrodes are relatively simple to recover after the experiments, via the loosening of screws. To prevent the plugging of OEPs laser sources from altering the stability of recordings, the OEPs fibers can be transiently anchored to the hat via the tightening of screws. We test the stability of recordings in the mouse hippocampus under three different conditions: acute head-fixed, chronic head-fixed, and chronic freely moving. Drift in spike waveforms is significantly smaller in chronic compared to acute conditions, with the plugging/unplugging of head-stage and fiber connectors not affecting much the recording stability. Overall, these tools generate stable recordings of place cell in chronic conditions, and make the recovery and reuse of electrode packages relatively simple.

Fixation of fractures of the condylar head of the mandible with a new magnesium-alloy biodegradable cannulated headless bone screw.

PubMed

Leonhardt, H; Franke, A; McLeod, N M H; Lauer, G; Nowak, A

2017-07-01

It is difficult to fix fractures of the condylar head of the mandible. Several techniques have been described which show satisfactory outcomes, but stability can be questionable, and some can cause irritation of the soft tissues. We describe a technique and first results of treating such fractures with resorbable magnesium-based headless bone screws (Magnezix ® 2.7mm CS; Syntellix AG, Hanover, Germany). Copyright © 2017 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Oil and gas well diversionary spool assembly

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

Reed, L.T.

1989-02-14

In combination with an oil and gas well that includes a casing head from which a string of tubing extends downwardly in a bore hole to a fluid producing zone, a diversionary spool assembly is described situated in a fixed position relative to the well head to control fluid flow from the well and also serve as a temporary mounting for a Christmas tree array of valves when maintenance work is to be performed on the well, the array of valves including an anchor flange on a lower end thereof.

Design and development of a Space Station proximity operations research and development mockup

NASA Technical Reports Server (NTRS)

Haines, Richard F.

1986-01-01

Proximity operations (Prox-Ops) on-orbit refers to all activities taking place within one km of the Space Station. Designing a Prox-Ops control station calls for a comprehensive systems approach which takes into account structural constraints, orbital dynamics including approach/departure flight paths, myriad human factors and other topics. This paper describes a reconfigurable full-scale mock-up of a Prox-Ops station constructed at Ames incorporating an array of windows (with dynamic star field, target vehicle(s), and head-up symbology), head-down perspective display of manned and unmanned vehicles, voice- actuated 'electronic checklist', computer-generated voice system, expert system (to help diagnose subsystem malfunctions), and other displays and controls. The facility is used for demonstrations of selected Prox-Ops approach scenarios, human factors research (work-load assessment, determining external vision envelope requirements, head-down and head-up symbology design, voice synthesis and recognition research, etc.) and development of engineering design guidelines for future module interiors.

Role of immediate recurrent laryngeal nerve reconstruction in surgery for thyroid cancers with fixed vocal cords.

PubMed

Iwaki, Shinobu; Maeda, Tatsuyoshi; Saito, Miki; Otsuki, Naoki; Takahashi, Miki; Wakui, Emi; Shinomiya, Hirotaka; Morimoto, Koichi; Inoue, Hiroyuki; Masuoka, Hiroo; Miyauchi, Akira; Nibu, Ken-Ichi

2017-03-01

Quality of voice after immediate recurrent laryngeal nerve (RLN) reconstruction in thyroid cancers has not been thoroughly studied. Thirteen patients with fixed vocal cords (fixed vocal cord group) and 8 patients with intact or impaired mobile vocal cords (mobile vocal cord group) who had immediate RLN reconstruction simultaneously with total thyroidectomy, and patients who had arytenoid adduction and thyroplasty for vocal cord paralysis caused by previous surgery (arytenoid adduction thyroplasty group) were enrolled in this study. Preoperative phonation efficiency index was significantly lower (p = .008) in the fixed vocal cord group than in the mobile vocal cord group. One year after surgery, all voice parameters of the patients in the fixed vocal cord group had improved, compared with their preoperative data. The fixed vocal cord group had attained satisfactory voice qualities equivalent to those of the mobile vocal cord group in terms of various voice parameters. The present results support the idea that immediate RLN reconstruction at the time of surgery for thyroid cancers may spare the need for subsequent arytenoid adduction thyroplasty even in the patients with preoperatively fixed vocal cords. © 2016 Wiley Periodicals, Inc. Head Neck 39: 427-431, 2017. © 2016 Wiley Periodicals, Inc.

SU-E-T-539: Fixed Versus Variable Optimization Points in Combined-Mode Modulated Arc Therapy Planning

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

Kainz, K; Prah, D; Ahunbay, E

2014-06-01

Purpose: A novel modulated arc therapy technique, mARC, enables superposition of step-and-shoot IMRT segments upon a subset of the optimization points (OPs) of a continuous-arc delivery. We compare two approaches to mARC planning: one with the number of OPs fixed throughout optimization, and another where the planning system determines the number of OPs in the final plan, subject to an upper limit defined at the outset. Methods: Fixed-OP mARC planning was performed for representative cases using Panther v. 5.01 (Prowess, Inc.), while variable-OP mARC planning used Monaco v. 5.00 (Elekta, Inc.). All Monaco planning used an upper limit of 91more » OPs; those OPs with minimal MU were removed during optimization. Plans were delivered, and delivery times recorded, on a Siemens Artiste accelerator using a flat 6MV beam with 300 MU/min rate. Dose distributions measured using ArcCheck (Sun Nuclear Corporation, Inc.) were compared with the plan calculation; the two were deemed consistent if they agreed to within 3.5% in absolute dose and 3.5 mm in distance-to-agreement among > 95% of the diodes within the direct beam. Results: Example cases included a prostate and a head-and-neck planned with a single arc and fraction doses of 1.8 and 2.0 Gy, respectively. Aside from slightly more uniform target dose for the variable-OP plans, the DVHs for the two techniques were similar. For the fixed-OP technique, the number of OPs was 38 and 39, and the delivery time was 228 and 259 seconds, respectively, for the prostate and head-and-neck cases. For the final variable-OP plans, there were 91 and 85 OPs, and the delivery time was 296 and 440 seconds, correspondingly longer than for fixed-OP. Conclusion: For mARC, both the fixed-OP and variable-OP approaches produced comparable-quality plans whose delivery was successfully verified. To keep delivery time per fraction short, a fixed-OP planning approach is preferred.« less

Analysis of antioxidative phenolic compounds in artichoke (Cynara scolymus L.).

PubMed

Wang, Mingfu; Simon, James E; Aviles, Irma Fabiola; He, Kan; Zheng, Qun-Yi; Tadmor, Yaakov

2003-01-29

Artichoke leaf is an herbal medicine known for a long time. A systematic antioxidant activity-directed fractionation procedure was used to purify antioxidative components from the aqueous methanol extractions of artichoke heads and leaves in this study. Seven active polyphenolic compounds were purified from artichoke, and structural elucidation of each was achieved using MS and NMR. Two of these compounds, apigenin-7-rutinoside and narirutin, were found to be unique to artichoke heads, this represents the first report of these compounds in the edible portion of this plant. The contents of these antioxidants and total phenols in dried artichoke samples from leaves and immature and mature heads of three varieties, Imperial Star, Green Globe, and Violet, were then analyzed and compared by colorimetric and validated HPLC methods. Significant differences by variety and plant organ were observed.

Flight Simulator Evaluation of Display Media Devices for Synthetic Vision Concepts

NASA Technical Reports Server (NTRS)

Arthur, J. J., III; Williams, Steven P.; Prinzel, Lawrence J., III; Kramer, Lynda J.; Bailey, Randall E.

2004-01-01

The Synthetic Vision Systems (SVS) Project of the National Aeronautics and Space Administration's (NASA) Aviation Safety Program (AvSP) is striving to eliminate poor visibility as a causal factor in aircraft accidents as well as enhance operational capabilities of all aircraft. To accomplish these safety and capacity improvements, the SVS concept is designed to provide a clear view of the world around the aircraft through the display of computer-generated imagery derived from an onboard database of terrain, obstacle, and airport information. Display media devices with which to implement SVS technology that have been evaluated so far within the Project include fixed field of view head up displays and head down Primary Flight Displays with pilot-selectable field of view. A simulation experiment was conducted comparing these display devices to a fixed field of view, unlimited field of regard, full color Helmet-Mounted Display system. Subject pilots flew a visual circling maneuver in IMC at a terrain-challenged airport. The data collected for this experiment is compared to past SVS research studies.

Automated tracking of whiskers in videos of head fixed rodents.

PubMed

Clack, Nathan G; O'Connor, Daniel H; Huber, Daniel; Petreanu, Leopoldo; Hires, Andrew; Peron, Simon; Svoboda, Karel; Myers, Eugene W

2012-01-01

We have developed software for fully automated tracking of vibrissae (whiskers) in high-speed videos (>500 Hz) of head-fixed, behaving rodents trimmed to a single row of whiskers. Performance was assessed against a manually curated dataset consisting of 1.32 million video frames comprising 4.5 million whisker traces. The current implementation detects whiskers with a recall of 99.998% and identifies individual whiskers with 99.997% accuracy. The average processing rate for these images was 8 Mpx/s/cpu (2.6 GHz Intel Core2, 2 GB RAM). This translates to 35 processed frames per second for a 640 px×352 px video of 4 whiskers. The speed and accuracy achieved enables quantitative behavioral studies where the analysis of millions of video frames is required. We used the software to analyze the evolving whisking strategies as mice learned a whisker-based detection task over the course of 6 days (8148 trials, 25 million frames) and measure the forces at the sensory follicle that most underlie haptic perception.

Automated Tracking of Whiskers in Videos of Head Fixed Rodents

PubMed Central

Clack, Nathan G.; O'Connor, Daniel H.; Huber, Daniel; Petreanu, Leopoldo; Hires, Andrew; Peron, Simon; Svoboda, Karel; Myers, Eugene W.

2012-01-01

We have developed software for fully automated tracking of vibrissae (whiskers) in high-speed videos (>500 Hz) of head-fixed, behaving rodents trimmed to a single row of whiskers. Performance was assessed against a manually curated dataset consisting of 1.32 million video frames comprising 4.5 million whisker traces. The current implementation detects whiskers with a recall of 99.998% and identifies individual whiskers with 99.997% accuracy. The average processing rate for these images was 8 Mpx/s/cpu (2.6 GHz Intel Core2, 2 GB RAM). This translates to 35 processed frames per second for a 640 px×352 px video of 4 whiskers. The speed and accuracy achieved enables quantitative behavioral studies where the analysis of millions of video frames is required. We used the software to analyze the evolving whisking strategies as mice learned a whisker-based detection task over the course of 6 days (8148 trials, 25 million frames) and measure the forces at the sensory follicle that most underlie haptic perception. PMID:22792058

Peripheral optogenetic stimulation induces whisker movement and sensory perception in head-fixed mice.

PubMed

Park, Sunmee; Bandi, Akhil; Lee, Christian R; Margolis, David J

2016-06-08

We discovered that optical stimulation of the mystacial pad in Emx1-Cre;Ai27D transgenic mice induces whisker movements due to activation of ChR2 expressed in muscles controlling retraction and protraction. Using high-speed videography in anesthetized mice, we characterize the amplitude of whisker protractions evoked by varying the intensity, duration, and frequency of optogenetic stimulation. Recordings from primary somatosensory cortex (S1) in anesthetized mice indicated that optogenetic whisker pad stimulation evokes robust yet longer latency responses than mechanical whisker stimulation. In head-fixed mice trained to report optogenetic whisker pad stimulation, psychometric curves showed similar dependence on stimulus duration as evoked whisker movements and S1 activity. Furthermore, optogenetic stimulation of S1 in expert mice was sufficient to substitute for peripheral stimulation. We conclude that whisker protractions evoked by optogenetic activation of whisker pad muscles results in cortical activity and sensory perception, consistent with the coding of evoked whisker movements by reafferent sensory input.

Arthroscopic knee surgery using the advanced flat panel high-resolution color head-mounted display

NASA Astrophysics Data System (ADS)

Nelson, Scott A.; Jones, D. E. Casey; St. Pierre, Patrick; Sampson, James B.

1997-06-01

The first ever deployed arthroscopic knee surgeries have been performed using a high resolution color head-mounted display (HMD) developed under the DARPA Advanced Flat Panel HMD program. THese procedures and several fixed hospital procedures have allowed both the system designers and surgeons to gain new insight into the use of a HMD for medical procedures in both community and combat support hospitals scenarios. The surgeons demonstrated and reported improved head-body orientation and awareness while using the HMD and reported several advantages and disadvantages of the HMD as compared to traditional CRT monitor viewing of the arthroscopic video images. The surgeries, the surgeon's comments, and a human factors overview of HMDs for Army surgical applications are discussed here.

Cancer

NASA Astrophysics Data System (ADS)

Murdin, P.

2000-11-01

(the Crab; abbrev. Cnc, genitive Cancri; area 506 sq. deg.) A northern zodiacal constellation which lies between Gemini and Leo, and culminates at midnight in late January. It represents the crab that, in Greek mythology, Hercules crushed underfoot during his fight with the multi-headed Hydra. The name of α Cancri, its brightest star, is Acubens, which comes from the Arabic word meaning `the claw...

Robustness of third family solutions for hybrid stars against mixed phase effects

NASA Astrophysics Data System (ADS)

Ayriyan, A.; Bastian, N.-U.; Blaschke, D.; Grigorian, H.; Maslov, K.; Voskresensky, D. N.

2018-04-01

We investigate the robustness of third family solutions for hybrid compact stars with a quark matter core that correspond to the occurrence of high-mass twin stars against a softening of the phase transition by means of a construction that mimics the effects of pasta structures in the mixed phase. We consider a class of hybrid equations of state that exploits a relativistic mean-field model for the hadronic as well as for the quark matter phase. We present parametrizations that correspond to branches of high-mass twin star pairs with maximum masses between 2.05 M⊙ and 1.48 M⊙ having radius differences between 3.2 and 1.5 km, respectively. When compared to a Maxwell construction with a fixed value of critical pressure Pc, the effect of the mixed phase construction consists in the occurrence of a region of pressures around Pc belonging to the coexistence of hadronic and quark matter phases between the onset pressure at PH and the end of the transition at PQ. The maximum broadening which would still allow mass-twin compact stars is found to be (PQ-PH)max≈Pc for all parametrizations within the present class of models. At least the heavier of the neutron stars of the binary merger GW170817 could have been a member of the third family of hybrid stars. We present the example of another class of hybrid star equations of state for which the appearance of the third family branch is not as robust against mixed phase effects as that of the present work.

An XMM Investigation of Non-Thermal Phenomena in the Winds of Early-Type Stars

NASA Technical Reports Server (NTRS)

Waldron, Wayne L.; Mushotzky, Richard (Technical Monitor)

2002-01-01

The X-ray emission from early-type stars is believed to arise from a stellar wind distribution of shocks. Hence, X-ray analyses of these stars must include the effects of stellar wind X-ray absorption, which, in general dominates the ISM absorption. Although the absorption cross sections for the wind and ISM are essentially identical above 1 keV, there is substantial differences below 1 keV. Typically, if one only uses ISM cross sections to obtain fits to X-ray spectra, the fits usually indicate a model deficiency at energies below 1 keV which is attributed to the large increase in ISM cross sections at these energies. This deficiency can be eliminated by using stellar wind absorption models with a fixed ISM component. Since all early-type stars have substantial X-ray emission below 1 keV, than inclusion of wind absorption has proven to be a critical component in fitting X-ray spectra at low energies, verifying that these X-rays are indeed arising from within the stellar wind.

UKIRT fast guide system improvements

NASA Astrophysics Data System (ADS)

Balius, Al; Rees, Nicholas P.

1997-09-01

The United Kingdom Infra-Red Telescope (UKIRT) has recently undergone the first major upgrade program since its construction. One part of the upgrade program was an adaptive tip-tilt secondary mirror closed with a CCD system collectively called the fast guide system. The installation of the new secondary and associated systems was carried out in the first half of 1996. Initial testing of the fast guide system has shown great improvement in guide accuracy. The initial installation included a fixed integration time CCD. In the first part of 1997 an integration time controller based on computed guide star luminosity was implemented in the fast guide system. Also, a Kalman type estimator was installed in the image tracking loop based on a dynamic model and knowledge of the statistical properties of the guide star position error measurement as a function of computed guide star magnitude and CCD integration time. The new configuration was tested in terms of improved guide performance nd graceful degradation when tracking faint guide stars. This paper describes the modified fast guide system configuration and reports the results of performance tests.

Approximations to galaxy star formation rate histories: properties and uses of two examples

NASA Astrophysics Data System (ADS)

Cohn, J. D.

2018-05-01

Galaxies evolve via a complex interaction of numerous different physical processes, scales and components. In spite of this, overall trends often appear. Simplified models for galaxy histories can be used to search for and capture such emergent trends, and thus to interpret and compare results of galaxy formation models to each other and to nature. Here, two approximations are applied to galaxy integrated star formation rate histories, drawn from a semi-analytic model grafted onto a dark matter simulation. Both a lognormal functional form and principal component analysis (PCA) approximate the integrated star formation rate histories fairly well. Machine learning, based upon simplified galaxy halo histories, is somewhat successful at recovering both fits. The fits to the histories give fixed time star formation rates which have notable scatter from their true final time rates, especially for quiescent and "green valley" galaxies, and more so for the PCA fit. For classifying galaxies into subfamilies sharing similar integrated histories, both approximations are better than using final stellar mass or specific star formation rate. Several subsamples from the simulation illustrate how these simple parameterizations provide points of contact for comparisons between different galaxy formation samples, or more generally, models. As a side result, the halo masses of simulated galaxies with early peak star formation rate (according to the lognormal fit) are bimodal. The galaxies with a lower halo mass at peak star formation rate appear to stall in their halo growth, even though they are central in their host halos.

The ATLAS3D Project - XXX. Star formation histories and stellar population scaling relations of early-type galaxies

NASA Astrophysics Data System (ADS)

McDermid, Richard M.; Alatalo, Katherine; Blitz, Leo; Bournaud, Frédéric; Bureau, Martin; Cappellari, Michele; Crocker, Alison F.; Davies, Roger L.; Davis, Timothy A.; de Zeeuw, P. T.; Duc, Pierre-Alain; Emsellem, Eric; Khochfar, Sadegh; Krajnović, Davor; Kuntschner, Harald; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Scott, Nicholas; Serra, Paolo; Weijmans, Anne-Marie; Young, Lisa M.

2015-04-01

We present the stellar population content of early-type galaxies from the ATLAS3D survey. Using spectra integrated within apertures covering up to one effective radius, we apply two methods: one based on measuring line-strength indices and applying single stellar population (SSP) models to derive SSP-equivalent values of stellar age, metallicity, and alpha enhancement; and one based on spectral fitting to derive non-parametric star formation histories, mass-weighted average values of age, metallicity, and half-mass formation time-scales. Using homogeneously derived effective radii and dynamically determined galaxy masses, we present the distribution of stellar population parameters on the Mass Plane (MJAM, σe, R^maj_e), showing that at fixed mass, compact early-type galaxies are on average older, more metal-rich, and more alpha-enhanced than their larger counterparts. From non-parametric star formation histories, we find that the duration of star formation is systematically more extended in lower mass objects. Assuming that our sample represents most of the stellar content of today's local Universe, approximately 50 per cent of all stars formed within the first 2 Gyr following the big bang. Most of these stars reside today in the most massive galaxies (>1010.5 M⊙), which themselves formed 90 per cent of their stars by z ˜ 2. The lower mass objects, in contrast, have formed barely half their stars in this time interval. Stellar population properties are independent of environment over two orders of magnitude in local density, varying only with galaxy mass. In the highest density regions of our volume (dominated by the Virgo cluster), galaxies are older, alpha-enhanced, and have shorter star formation histories with respect to lower density regions.

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

El-Badry, Kareem; Geha, Marla; Wetzel, Andrew

We examine the effects of stellar feedback and bursty star formation on low-mass galaxies (M{sub star} = 2 × 10{sup 6} − 5 × 10{sup 10} M{sub ⊙}) using the Feedback in Realistic Environments (FIRE) simulations. While previous studies emphasized the impact of feedback on dark matter profiles, we investigate the impact on the stellar component: kinematics, radial migration, size evolution, and population gradients. Feedback-driven outflows/inflows drive significant radial stellar migration over both short and long timescales via two processes: (1) outflowing/infalling gas can remain star-forming, producing young stars that migrate ∼1 kpc within their first 100 Myr, and (2) gas outflows/inflows drive strong fluctuations in the globalmore » potential, transferring energy to all stars. These processes produce several dramatic effects. First, galaxies’ effective radii can fluctuate by factors of >2 over ∼200 Myr, and these rapid size fluctuations can account for much of the observed scatter in the radius at fixed M{sub star}. Second, the cumulative effects of many outflow/infall episodes steadily heat stellar orbits, causing old stars to migrate outward most strongly. This age-dependent radial migration mixes—and even inverts—intrinsic age and metallicity gradients. Thus, the galactic-archaeology approach of calculating radial star formation histories from stellar populations at z = 0 can be severely biased. These effects are strongest at M{sub star} ≈ 10{sup 7–9.6} M{sub ⊙}, the same regime where feedback most efficiently cores galaxies. Thus, detailed measurements of stellar kinematics in low-mass galaxies can strongly constrain feedback models and test baryonic solutions to small-scale problems in ΛCDM.« less

The Very Slow Wind from the Pulsating Semiregular Red Giant, L2 Puppis

NASA Technical Reports Server (NTRS)

Jura, M.; Chen, C.; Plavchan, P.

2002-01-01

We have obtained 1 1.7 and 17.9 micron images at the Keck I telescope of the circumstellar dust emission from L(sub 2) Pup, which is one of the nearest ( D = 61 pc) mass-losing, pulsating red giants that has a substantial infra-red excess. We propose that the star is losing mass at a rate of approx.3 x 10(exp -7) Solar Mass/yr. Given its relatively low luminosity (approx. 1500 Solar Luminosity), relatively high effective temperature (near 3400 K), relatively short period (approx. 140 days), and inferred gas outflow speed of 3.5 km/s, standard models for dust-driven mass loss do not apply. Instead, the wind may be driven by the stellar pulsations, with radiation pressure on dust being relatively unimportant. as described in some recent calculations. L(sub 2) Pup may serve as the prototype of this phase of stellar evolution, in which a star could lose approx. 15% of its initial main-sequence mass. Subject headings: circumstellar matter - stars: individual (L2 Puppis) - stars: mass loss

Galactic scale gas flows in colliding galaxies: 3-dimensional, N-body/hydrodynamics experiments

NASA Technical Reports Server (NTRS)

Lamb, Susan A.; Gerber, Richard A.; Balsara, Dinshaw S.

1994-01-01

We present some results from three dimensional computer simulations of collisions between models of equal mass galaxies, one of which is a rotating, disk galaxy containing both gas and stars and the other is an elliptical containing stars only. We use fully self consistent models in which the halo mass is 2.5 times that of the disk. In the experiments we have varied the impact parameter between zero (head on) and 0.9R (where R is the radius of the disk), for impacts perpendicular to the disk plane. The calculations were performed on a Cray 2 computer using a combined N-body/smooth particle hydrodynamics (SPH) program. The results show the development of complicated flows and shock structures in the direction perpendicular to the plane of the disk and the propagation outwards of a density wave in both the stars and the gas. The collisional nature of the gas results in a sharper ring than obtained for the star particles, and the development of high volume densities and shocks.

The NASA Neutron Star Grand Challenge: The coalescences of Neutron Star Binary System

NASA Astrophysics Data System (ADS)

Suen, Wai-Mo

1998-04-01

NASA funded a Grand Challenge Project (9/1996-1999) for the development of a multi-purpose numerical treatment for relativistic astrophysics and gravitational wave astronomy. The coalescence of binary neutron stars is chosen as the model problem for the code development. The institutes involved in it are the Argonne Lab, Livermore lab, Max-Planck Institute at Potsdam, StonyBrook, U of Illinois and Washington U. We have recently succeeded in constructing a highly optimized parallel code which is capable of solving the full Einstein equations coupled with relativistic hydrodynamics, running at over 50 GFLOPS on a T3E (the second milestone point of the project). We are presently working on the head-on collisions of two neutron stars, and the inclusion of realistic equations of state into the code. The code will be released to the relativity and astrophysics community in April of 1998. With the full dynamics of the spacetime, relativistic hydro and microphysics all combined into a unified 3D code for the first time, many interesting large scale calculations in general relativistic astrophysics can now be carried out on massively parallel computers.

Shocked and Scorched - Free-Floating Evaporating Gas Globules and Star Formation

NASA Astrophysics Data System (ADS)

Sahai, Raghvendra; Morris, Mark R.; Claussen, Mark J.

2014-07-01

Massive stars have a strong feedback effect on their environment, via their winds, UV radiation, and ultimately, supernova blast waves, all of which can alter the likelihood for the formation of stars in nearby clouds and limit the accretion process of nearby protostars. Free-floating Evaporating Gaseous Globules, or frEGGs, are a newly recognized class of stellar nurseries embedded within the giant HII regions found in massive star-formation region (MSFRs). We recently discovered the prototype frEGG in the Cygnus MSFR with HST. Further investigation using the Spitzer and Herschel archives have revealed a much larger number (>50) in Cygnus and other MSFRs. Our molecular-line observations of these show the presence of dense clouds with total masses of cool molecular gas exceeding 0.5 to a few Msun associated with these objects, thereby disproving the initial hypothesis based on their morphology that these have an origin similar to the proplyds (cometary-shaped photoevaporating protoplanetary disks) found in Orion. We report the results of our molecular-line studies and detailed high-resolution optical (with HST) or near-IR (with AO at the Keck Observatory) imaging of a few frEGGs in Cygnus, Carina and the W5 MSFRs. The images show the presence of young stars with associated outflow cavities and/or jets in the heads of the tadpole-shaped frEGGs. These results support our hypothesis that frEGGs are density concentrations originating in giant molecular clouds, that, when subject to the compression by the strong winds and ionization from massive stars in these MSFRs, become active star-forming cores. In summary, by virtue of their distinct, isolated morphologies, frEGGs offer us a clean probe of triggered star formation on small scales in the vicinity of massive stars.

Star-Formation in Free-Floating Evaporating Gaseous Globules

NASA Astrophysics Data System (ADS)

Sahai, Raghvendra

2017-08-01

We propose to study the stellar embryos in select members of a newly recognized class of Free-floating Evaporating Gaseous Globules (frEGGS) embedded in HII regions and having head-tail shapes. We discovered two of these in the Cygnus massive star-forming region (MSFR) with HST, including one of the most prominent members of this class (IRAS20324). Subsequent archival searches of Spitzer imaging of MSFRs has allowed us to build a statistical sample of frEGGs. Our molecular-line observations show the presence of dense molecular cores with total gas masses of (0.5-few) Msun in these objects, and our radio continuum images and Halpha images (from the IPHAS survey) reveal bright photo-ionized peripheries around these objects. We hypothesize that frEGGs are density concentrations originating in giant molecular clouds, that, when subject to the sculpting and compression by strong winds and UV radiation from massive stars, become active star-forming cores. For the 4 frEGGs with HST or near-IR AO images showing young stars and bipolar cavities produced by their jets or collimated outflows, the symmetry axis points roughly toward the external ionizing star or star cluster - exciting new evidence for our overpressure-induced star formation hypothesis. We propose to test this hypothesis by imaging 24 frEGGs in two nearby MSFRs that represent different radiation-dominated environments. Using ACS imaging with filters F606W, F814W, & F658N (Ha+[NII]), we will search for jets and outflow-excavated cavities, investigate the stellar nurseries inside frEGGs, and determine whether the globules are generally forming multiple star systems or small clusters, as in IRAS20324.

Bubbly Little Star

NASA Technical Reports Server (NTRS)

2007-01-01

In this processed Spitzer Space Telescope image, baby star HH 46/47 can be seen blowing two massive 'bubbles.' The star is 1,140 light-years away from Earth.

The infant star can be seen as a white spot toward the center of the Spitzer image. The two bubbles are shown as hollow elliptical shells of bluish-green material extending from the star. Wisps of green in the image reveal warm molecular hydrogen gas, while the bluish tints are formed by starlight scattered by surrounding dust.

These bubbles formed when powerful jets of gas, traveling at 200 to 300 kilometers per second, or about 120 to 190 miles per second, smashed into the cosmic cloud of gas and dust that surrounds HH 46/47. The red specks at the end of each bubble show the presence of hot sulfur and iron gas where the star's narrow jets are currently crashing head-on into the cosmic cloud's gas and dust material.

Whenever astronomers observe a star, or snap a stellar portrait, through the lens of any telescope, they know that what they are seeing is slightly blurred. To clear up the blurring in Spitzer images, astronomers at the Jet Propulsion Laboratory developed an image processing technique for Spitzer called Hi-Res deconvolution.

This process reduces blurring and makes the image sharper and cleaner, enabling astronomers to see the emissions around forming stars in greater detail. When scientists applied this image processing technique to the Spitzer image of HH 46/47, they were able to see winds from the star and jets of gas that are carving the celestial bubbles.

This infrared image is a three-color composite, with data at 3.6 microns represented in blue, 4.5 and 5.8 microns shown in green, and 24 microns represented as red.

VMAT vs. 7-Field-IMRT: Assessing the Dosimetric Parameters of Prostate Cancer Treatment with a 292-Patient Sample

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

Kopp, Robert W.; Duff, Michael, E-mail: mduff@cancercarewny.com; Catalfamo, Frank

2011-01-01

We compared normal tissue radiation dose for the treatment of prostate cancer using 2 different radiation therapy delivery methods: volumetric modulated arc therapy (VMAT) vs. fixed-field intensity-modulated radiation therapy (IMRT). Radiotherapy plans for 292 prostate cancer patients treated with VMAT to a total dose of 7740 cGy were analyzed retrospectively. Fixed-angle, 7-field IMRT plans were created using the same computed tomography datasets and contours. Radiation doses to the planning target volume (PTV) and organs at risk (bladder, rectum, penile bulb, and femoral heads) were measured, means were calculated for both treatment methods, and dose-volume comparisons were made with 2-tailed, pairedmore » t-tests. The mean dose to the bladder was lower with VMAT at all measured volumes: 5, 10, 15, 25, 35, and 50% (p < 0.05). The mean doses to 5 and 10% of the rectum, the high-dose regions, were lower with VMAT (p < 0.05). The mean dose to 15% of the rectal volume was not significantly different (p = 0.95). VMAT exposed larger rectal volumes (25, 35, and 50%) to more radiation than fixed-field IMRT (p < 0.05). Average mean dose to the penile bulb (p < 0.05) and mean dose to 10% of the femoral heads (p < 0.05) were lower with VMAT. VMAT therapy for prostate cancer has dosimetric advantages for critical structures, notably for high-dose regions compared with fixed-field IMRT, without compromising PTV coverage. This may translate into reduced acute and chronic toxicity.« less

Bone conduction responses of middle ear structures in Thiel embalmed heads

NASA Astrophysics Data System (ADS)

Arnold, Andreas; Stieger, Christof; Caversaccio, Marco; Kompis, Martin; Guignard, Jérémie

2015-12-01

Thiel-embalmed human whole-head specimens offer a promising alternative model for bone conduction (BC) studies of middle ear structures. In this work we present the Thiel model's linearity and stability over time as well as its possible use in the study of a fixed ossicle chain. Using laser Doppler vibrometry (LDV), the motion of the retroauricular skull, the promontory, the stapes footplate and the round window (RW) were measured. A bone-anchored hearing aid stimulated the ears with step sinus tones logarithmically spread between 0.1 and 10 kHz. Linearity of the model was verified using input levels in steps of 10 dBV. The stability of the Thiel model over time was examined with measurements repeated after hours and weeks. The influence of a cement-fixed stapes was assessed. The middle ear elements measured responded linearly in amplitude for the applied input levels (100, 32.6, and 10 mV). The variability of measurements for both short- (2 h) and long-term (4-16 weeks) repetitions in the same ear was lower than the interindividual difference. The fixation of the stapes induced a lowered RW displacement for frequencies near 750 Hz (-4 dB) and an increased displacement for frequencies above 1 kHz (max. +3.7 dB at 4 kHz). LDV assessment of BC-induced middle ear motion in Thiel heads can be performed with stable results. The vibratory RW response is affected by the fixation of the stapes, indicating a measurable effect of ossicle chain inertia on BC response in Thiel embalmed heads.

Reassessment of the Necessity of the Proton Gantry: Analysis of Beam Orientations From 4332 Treatments at the Massachusetts General Hospital Proton Center Over the Past 10 Years

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

Yan, Susu, E-mail: syan5@mgh.harvard.edu; Lu, Hsiao-Ming; Flanz, Jay

2016-05-01

Purpose: To retrospectively analyze the beam approaches used in gantry-based proton treatments, and to reassess the practical advantages of the gantry, compared with beam approaches that are achievable without a gantry, in the context of present-day technology. Methods and Materials: We reviewed the proton therapy plans of 4332 patients treated on gantries at our hospital, delivered by the double scattering technique (n=4228) and, more recently, pencil beam scanning (PBS) (n=104). Beam approaches, relative to the patient frame, were analyzed individually to identify cases that could be treated without a gantry. Three treatment configurations were considered, with the patient in lying position,more » sitting position, or both. The FIXED geometry includes a fixed horizontal portal. The BEND geometry enables a limited vertical inflection of the beam by up to 20°. The MOVE geometry allows for flexibility of the patient head and body setup. Results: The percentage of patients with head and neck tumors that could be treated without a gantry using double scattering was 44% in FIXED, 70% in 20° BEND, and 100% in 90° MOVE. For torso regions, 99% of patients could be treated in 20° BEND. Of 104 PBS treatments, all but 1 could be reproduced with FIXED geometry. The only exception would require a 10° BEND capability. Note here that the PBS treatments were applied to select anatomic sites, including only 2 patients with skull-base tumors. Conclusions: The majority of practical beam approaches can be realized with gantry-less delivery, aided by limited beam bending and patient movements. Practical limitations of the MOVE geometry, and treatments requiring a combination of lying and sitting positions, may lower the percentage of head and neck patients who could be treated without a gantry. Further investigation into planning, immobilization, and imaging is needed to remove the practical limitations and to facilitate proton treatment without a gantry.« less

The Star-Forming Main Sequence as a Natural Consequence of the Central Limit Theorem

NASA Astrophysics Data System (ADS)

Kelson, Daniel David

2015-08-01

Star-formation rates (SFR) of disk galaxies correlate with stellar mass, with a small dispersion in SSFR at fixed mass, sigma~0.3 dex. With such scatter this star-formation main sequence (SFMS) has been interpreted as deterministic and fundamental. Here I demonstrate that such a correlation arises naturally from the central limit theorem. The derivation begins by approximating in situ stellar mass growth as a stochastic process, much like a random walk, where the expectation of SFR at any time is equal to the SFR at the previous time. The SFRs of real galaxies, however, do not experience wholly random stochastic changes over time, but change in a highly correlated fashion due to the long reach of gravity and the correlation of structure in the universe. We therefore generalize the results for star-formation as a stochastic process that has random correlations over random and potentially infinite timescales. For unbiased samples of (disk) galaxies we derive expectation values for SSFR and its scatter, such that =2/T, and Sig[SFR/M]=. Note that this relative scatter is independent of mass and time. This derived correlation between SFR and stellar mass, and its evolution, matches published data to z=10 with sufficient accuracy to constrain cosmological parameters from the data. This statistical approach to the diversity of star-formation histories reproduces several important observables, including: the scatter in SSFR at fixed mass; the forms of SFHs of nearby dwarf galaxies and the Milky Way. At least one additional process beyond a single one responsible for in situ stellar mass growth will be required to match the evolution of the stellar mass function, and we discuss ways to generalize the framework. The implied dispersion in SFHs, and the SFMS's insensitivity to timescales of stochasticity, thus substantially limits the ability to connect massive galaxies to their progenitors over long cosmic baselines. Such analytical work shows promise for statisically modeling distributions of galaxies over cosmic time, in a manner particularly indpendent of the thorny uncertainties in sub-grid astrophysics of modern cosmological simulations.

Maximizing water use efficiency in designing microirrigation unit (IrriLab Software)

NASA Astrophysics Data System (ADS)

Baiamonte, Giorgio

2016-04-01

As the year 2050 approaches, the world population will reach 9 billion - so does the challenge of doubling crop yields. To meet this crop yields demand, the associated dramatic improving of water productivity (WP) must necessarily be accompanied by maximization of water use efficiency (WUE) (Ragab 2011, UNEP 2014). In this work, a recently developed software (IrriLab, https://www.facebook.com/irrilab) moving in this direction is presented. IrriLab is a very simple toll allows to design microirrigation unit optimizing WUE, pressure energy and irrigation unit costs. Irrigation software available in commerce provide microirrigation system designs, by mainly looking at the maximum flow rate uniformity criteria. Thus, each emitter installed along the laterals operates with an operating pressure head occurring in between an established range of pressure head variability (Dh < Dhadm). However, the latter condition does not always corresponds to the cheapest and to the maximizing WUE solution; in fact, it is not assured if the entire range of the admitted pressure head is profited and used by the emitters. IrriLab allows this occurrence because, for the entire Irrigation Unit Area, IUA, each design solution assures that at least two emitters rigorously operates, one with the minimum admitted pressure head, and the other one with the maximum admitted (Dh = Dhadm), (Baiamonte et al., 2015; Baiamonte, 2016). The same extreme values of pressure head are those that in the common design criteria delimit the range of pressure head, but without assuring their achievement. Compared to the common design criteria, this condition i) for fixed laterals' length and inside diameter, allows reducing the inlet required pressure head whereas, ii) for fixed pressure head at the inlet, provides an increasing in laterals and manifold lengths and in the associated IUA. Based on analytical solutions, IrriLab follows a very simple rectangular sketch, any way oriented in the space, and defined by two slope values, one for the laterals and one for the manifold. By considering the possible combinations of i) horizontal, downward or upward sloped laterals and manifold, ii) the manifold position in respect to the laterals and iii) the inlet position in respect to the manifold, which can be equal to 0%, 24% or 50%, in respect to their lengths (Baiamonte, 2016), IrriLab accounts for 25 optimal irrigation unit layouts, for each of them providing maximum WUE.

Spin-one bilinear-biquadratic model on a star lattice

NASA Astrophysics Data System (ADS)

Lee, Hyun-Yong; Kawashima, Naoki

2018-05-01

We study the ground-state phase diagram of the S =1 bilinear-biquadratic model (BLBQ) on the star lattice with the state-of-art tensor network algorithms. The system has four phases: the ferromagnetic, antiferromagnetic, ferroquadrupolar, and spin-liquid phases. The phases and their phase boundaries are determined by examining various local observables, correlation functions, and transfer matrices exhaustively. The spin-liquid phase, which is the first quantum disordered phase found in the two-dimensional BLBQ model, is gapped and devoid of any conventional long-range order. It is also characterized by fixed-parity virtual bonds in the tensor network formalism, analogous to the Haldane phase, while the parity varies depending on the location of the bond.

Temperature dependence of attitude sensor coalignments on the Solar Maximum Mission (SMM)

NASA Technical Reports Server (NTRS)

Pitone, D. S.; Eudell, A. H.; Patt, F. S.

1989-01-01

Results are presented on the temperature correlation of the relative coalignment between the fine pointing sun sensor (FPSS) and fixed head star trackers (FHSTs) on the Solar Maximum Mission (SMM). This correlation can be caused by spacecraft electronic and mechanical effects. Routine daily measurements reveal a time dependent sensor coalignment variation. The magnitude of the alignment variation is on the order of 120 arc seconds (arc sec), which greatly exceeds the prelaunch thermal structural analysis estimate of 15 acr sec. Differences between FPSS-only and FHST-only yaw solutions as a function of mission day are correlated with the relevant spacecraft temperature. If unaccounted for, the sensor misalignments due to thermal effects are a significant source of error in attitude determination accuracy. Prominent sources of temperature variation are identified and correlated with the temperature profile observed on the SMM. It was determined that even relatively small changes in spacecraft temperature can affect the coalignments between the attitude hardware on the SMM and the science instrument support plate and that frequent recalibration of sensor alignments is necessary to compensate for this effect. An alterntive to frequent recalibration is to model the variation of alignments as a function of temperature and use this to maintain accurate ground or onboard alignment estimates. These flight data analysis results may be important consierations for prelaunch analysis of future missions.

Spacecraft attitude determination accuracy from mission experience

NASA Technical Reports Server (NTRS)

Brasoveanu, D.; Hashmall, J.

1994-01-01

This paper summarizes a compilation of attitude determination accuracies attained by a number of satellites supported by the Goddard Space Flight Center Flight Dynamics Facility. The compilation is designed to assist future mission planners in choosing and placing attitude hardware and selecting the attitude determination algorithms needed to achieve given accuracy requirements. The major goal of the compilation is to indicate realistic accuracies achievable using a given sensor complement based on mission experience. It is expected that the use of actual spacecraft experience will make the study especially useful for mission design. A general description of factors influencing spacecraft attitude accuracy is presented. These factors include determination algorithms, inertial reference unit characteristics, and error sources that can affect measurement accuracy. Possible techniques for mitigating errors are also included. Brief mission descriptions are presented with the attitude accuracies attained, grouped by the sensor pairs used in attitude determination. The accuracies for inactive missions represent a compendium of missions report results, and those for active missions represent measurements of attitude residuals. Both three-axis and spin stabilized missions are included. Special emphasis is given to high-accuracy sensor pairs, such as two fixed-head star trackers (FHST's) and fine Sun sensor plus FHST. Brief descriptions of sensor design and mode of operation are included. Also included are brief mission descriptions and plots summarizing the attitude accuracy attained using various sensor complements.

The 1.4-2.7 micron spectrum of the point source at the galactic center

NASA Technical Reports Server (NTRS)

Treffers, R. R.; Fink, U.; Larson, H. P.; Gautier, T. N., III

1976-01-01

The spectrum of the 2-micron point source at the galactic center is presented over the range from 1.4 to 2.7 microns. The two-level-transition CO band heads are seen near 2.3 microns, confirming that the radiation from this source is due to a cool supergiant star. The heliocentric radial velocity is found to be - 173 (+ or -90) km/s and is consistent with the star being in orbit about a dense galactic nucleus. No evidence is found for Brackett-gamma emission, and no interstellar absorption features are seen. Upper limits for the column densities of interstellar H2, CH4, CO, and NH3 are derived.

The COROT telescope

NASA Astrophysics Data System (ADS)

Viard, Thierry

2017-11-01

The COROT telescope, of which the customer is the French "INSU" / "CNES" (Institut National des Sciences de l'Univers / Centre National des Etudes Spatiales) is in fact a very precise and stable imaging instrument, which will be pointed towards fixed areas in the sky (each containing more than 3000 target stars) for periods of at least 5 months, in order to carry out its two missions.

Isolating signatures of major cloud-cloud collisions using position-velocity diagrams

NASA Astrophysics Data System (ADS)

Haworth, T. J.; Tasker, E. J.; Fukui, Y.; Torii, K.; Dale, J. E.; Shima, K.; Takahira, K.; Habe, A.; Hasegawa, K.

2015-06-01

Collisions between giant molecular clouds are a potential mechanism for triggering the formation of massive stars, or even super star clusters. The trouble is identifying this process observationally and distinguishing it from other mechanisms. We produce synthetic position-velocity diagrams from models of cloud-cloud collisions, non-interacting clouds along the line of sight, clouds with internal radiative feedback and a more complex cloud evolving in a galactic disc, to try and identify unique signatures of collision. We find that a broad bridge feature connecting two intensity peaks, spatially correlated but separated in velocity, is a signature of a high-velocity cloud-cloud collision. We show that the broad bridge feature is resilient to the effects of radiative feedback, at least to around 2.5 Myr after the formation of the first massive (ionizing) star. However for a head-on 10 km s-1 collision, we find that this will only be observable from 20 to 30 per cent of viewing angles. Such broad-bridge features have been identified towards M20, a very young region of massive star formation that was concluded to be a site of cloud-cloud collision by Torii et al., and also towards star formation in the outer Milky Way by Izumi et al.

Seven-star needle stimulation improves language and social interaction of children with autistic spectrum disorders.

PubMed

Chan, Agnes S; Cheung, Mei-Chun; Sze, Sophia L; Leung, Winnie W

2009-01-01

This is a randomized controlled trial that aimed to evaluate the effect of the Seven-star Needle Stimulation treatment on children with Autistic Spectrum Disorders (ASD). Thirty-two children with ASD were assigned randomly into the treatment and control groups. Children in the treatment group underwent 30 sessions of stimulation over 6 weeks, while children in the control group were on a waiting list and did not receive treatment during this period of time. Intervention consisted of a treatment regime comprising of 30 sessions of Seven-star Needle Stimulation, delivered over 6 weeks. Each session lasted 5 to 10 min, children in the treatment group were stimulated at the front and back sides of their body and the head by using Seven-star Needles. The change in the children's behavior was evaluated using parents' report and neurophysiological changes were measured by quantitative EEG (qEEG). Results showed that the treatment group demonstrated significant improvement in language and social interaction, but not in stereotyped behavior or motor function, compared to the control group. qEEG spectral amplitudes in the treatment, but not in the control group, were also reduced significantly. The results suggested that Seven-star Needle Stimulation might be an effective intervention to improve language and social functioning of children with ASD.

On the stability and collisions in triple stellar systems

NASA Astrophysics Data System (ADS)

He, Matthias Y.; Petrovich, Cristobal

2018-02-01

A significant fraction of main-sequence (MS) stars are part of a triple system. We study the long-term stability and dynamical outcomes of triple stellar systems using a large number of long-term direct N-body integrations with relativistic precession. We find that the previously proposed stability criteria by Eggleton & Kiseleva and Mardling & Aarseth predict the stability against ejections reasonably well for a wide range of parameters. Assuming that the triple stellar systems follow orbital and mass distributions from FGK binary stars in the field, we find that ˜ 1 per cent and ˜ 0.5 per cent of the triple systems lead to a direct head-on collision (impact velocity ˜ escape velocity) between MS stars and between a MS star and a stellar-mass compact object, respectively. We conclude that triple interactions are the dominant channel for direct collisions involving a MS star in the field with a rate of one event every ˜100 years in the Milky Way. We estimate that the fraction of triple systems that form short-period binaries is up to ˜ 23 per cent with only up to ˜ 13 per cent being the result of three-body interactions with tidal dissipation, which is consistent with previous work using a secular code.

Gravitational radiation, inspiraling binaries, and cosmology

NASA Technical Reports Server (NTRS)

Chernoff, David F.; Finn, Lee S.

1993-01-01

We show how to measure cosmological parameters using observations of inspiraling binary neutron star or black hole systems in one or more gravitational wave detectors. To illustrate, we focus on the case of fixed mass binary systems observed in a single Laser Interferometer Gravitational-wave Observatory (LIGO)-like detector. Using realistic detector noise estimates, we characterize the rate of detections as a function of a threshold SNR Rho(0), H0, and the binary 'chirp' mass. For Rho(0) = 8, H0 = 100 km/s/Mpc, and 1.4 solar mass neutron star binaries, the sample has a median redshift of 0.22. Under the same assumptions but independent of H0, a conservative rate density of coalescing binaries implies LIGO will observe about 50/yr binary inspiral events. The precision with which H0 and the deceleration parameter q0 may be determined depends on the number of observed inspirals. For fixed mass binary systems, about 100 observations with Rho(0) = 10 in the LIGO will give H0 to 10 percent in an Einstein-DeSitter cosmology, and 3000 will give q0 to 20 percent. For the conservative rate density of coalescing binaries, 100 detections with Rho(0) = 10 will require about 4 yrs.

A Statistical Approach to Passive Target Tracking.

DTIC Science & Technology

1981-04-01

a fixed heading of 90 degrees. For 7F. A. Graybill , An Introduction to Linear Statistical Models , Vol. 1, New York: John Wiley&-Sons -Inc. (1961). 13...likelihood estimators. 12 NCSC TM 311-81 The adjustment for a changing error variance is easy using the linear model approach; i.e., use weighted

The effect of radial head implant shape on radiocapitellar kinematics during in vitro forearm rotation.

PubMed

Shannon, Hannah L; Deluce, Simon R; Giles, Joshua W; Johnson, James A; King, Graham J W

2015-02-01

A number of radial head implants are in clinical use for the management of radial head fractures and their sequelae. However, the optimal shape of a radial head implant to ensure proper tracking relative to the capitellum has not been established. This in vitro biomechanical study compared radiocapitellar joint kinematics for 3 radial head implant designs as well as the native head. Eight cadaveric upper extremities were tested using a forearm rotation simulator with the elbow at 90° of flexion. Motion of the radius relative to the capitellum was optically tracked. A stem was navigated into a predetermined location and cemented in place. Three unipolar implant shapes were tested: axisymmetric, reverse-engineered patient-specific, and population-based quasi-anatomic. The patient-specific and quasi-anatomic implants were derived from measurements performed on computed tomography models. Medial-lateral and anterior-posterior translation of the radial head with respect to the capitellum varied with forearm rotation and radial head condition. A significant difference in medial-lateral (P = .03) and anterior-posterior (P = .03) translation was found between the native radial head and the 3 implants. No differences were observed among the radial head conditions except for a difference in medial-lateral translation between the axisymmetric and patient-specific implants (P = .04). Radiocapitellar kinematics of the tested radial head implants were similar in all but one comparison, and all had different kinematics from the native radial head. Patient-specific radial head implants did not prove advantageous relative to conventional implant designs. The shape of the fixed stem unipolar radial head implants had little influence on radiocapitellar kinematics when optimally positioned in this testing model. Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Influence of vision on head stabilization strategies in older adults during walking.

PubMed

Cromwell, Ronita L; Newton, Roberta A; Forrest, Gail

2002-07-01

Maintaining balance during dynamic activities is essential for preventing falls in older adults. Head stabilization contributes to dynamic balance, especially during the functional task of walking. Head stability and the role of vision in this process have not been studied during walking in older adults. Seventeen older adults (76.2 +/- 6.9 years) and 20 young adults (26.0 +/- 3.4 years) walked with their eyes open (EO), with their eyes closed (EC), and with fixed gaze (FG). Participants performed three trials of each condition. Sagittal plane head and trunk angular velocities in space were obtained using an infrared camera system with passive reflective markers. Frequency analyses of head-on-trunk with respect to trunk gains and phases were examined for head-trunk movement strategies used for head stability. Average walking velocity, cadence, and peak head velocity were calculated for each condition. Differences between age groups demonstrated that older adults decreased walking velocity in EO (p =.022). FG (p = .021), and EC (p = .022). and decreased cadence during EC (p = .007). Peak head velocity also decreased across conditions (p < .0001) for older adults. Movement patterns demonstrated increased head stability during EO. diminished head stability with EC, and improved head stability with FG as older adult patterns resembled those of young adults. Increased stability of the lower extremity outcome measures for older adults was indicated by reductions in walking velocity and cadence. Concomitant increases in head stability were related to visual tasks. Increased stability may serve as a protective mechanism to prevent falls. Further, vision facilitates the head stabilization process for older adults to compensate for age-related decrements in other sensory systems subserving dynamic balance.

Retention Strength of Conical Welding Caps for Fixed Implant-Supported Prostheses.

PubMed

Nardi, Diego; Degidi, Marco; Sighinolfi, Gianluca; Tebbel, Florian; Marchetti, Claudio

This study evaluated the retention strength of welding caps for Ankylos standard abutments using a pull-out test. Each sample consisted of an implant abutment and its welding cap. The tests were performed with a Zwick Roell testing machine with a 1-kN load cell. The retention strength of the welding caps increased with higher abutment diameters and higher head heights and was comparable or superior to the values reported in the literature for the temporary cements used in implant dentistry. Welding caps provide a reliable connection between an abutment and a fixed prosthesis without the use of cement.

Physical Properties of UV-bright Clumps in Star-forming Galaxies at 0.5 ≤ z < 3

NASA Astrophysics Data System (ADS)

Guo, Yicheng; Rafelski, Marc; Bell, Eric F.; Dekel, Avishai; Mandelker, Nir; Primack, Joel R.; CANDELS

2018-06-01

Studying giant star-forming clumps in distant galaxies is important to understand galaxy formation and evolution. At present, however, observers and theorists have not reached a consensus on whether the observed “clumps” in distant galaxies are the same phenomenon that is seen in simulations. As a step to establish a benchmark of direct comparisons between observations and theories, we publish a sample of clumps constructed to represent the commonly observed “clumps” in the literature. This sample contains 3193 clumps detected from the rest-frame images of 1270 galaxies at 0.5≤z<3.0. The physical properties of clumps (e.g., rest-frame color, stellar mass, star formation rate, age, and dust extinction) are measured by fitting the spectral energy distribution (SED) to synthetic stellar population models. We carefully test the procedures of measuring clump properties, especially the method of subtracting background fluxes from the diffuse component of galaxies. With our fiducial background subtraction, we find a radial clump U-V color variation, where clumps close to galactic centers are redder than those in outskirts. The slope of the color gradient (clump color as a function of their galactocentric distance scaled by the semimajor axis of galaxies) changes with redshift and stellar mass of the host galaxies: at a fixed stellar mass, the slope becomes steeper toward low redshift, and at a fixed redshift, it becomes slightly steeper with stellar mass. Based on our SED fitting, this observed color gradient can be explained by a combination of a negative age gradient, a negative E(B-V) gradient, and a positive specific star formation rate gradient of the clumps. We also find that the color gradients of clumps are steeper than those of intra-clump regions. Correspondingly, the radial gradients of the derived physical properties of clumps are different from those of the diffuse component or intra-clump regions.

Head Start and Urban Children’s School Readiness: A Birth Cohort Study in 18 Cities

PubMed Central

Zhai, Fuhua; Brooks-Gunn, Jeanne; Waldfogel, Jane

2011-01-01

We used longitudinal data from a birth cohort study, the Fragile Families and Child Wellbeing Study, to investigate the links between Head Start and school readiness in a large and diverse sample of urban children at age 5 (N = 2,803; 18 cities). We found that Head Start attendance was associated with enhanced cognitive ability and social competence and reduced attention problems but not reduced internalizing or externalizing behavior problems. These findings were robust to model specifications (including models with city-fixed effects and propensity-scoring matching). Furthermore, the effects of Head Start varied by the reference group. Head Start was associated with improved cognitive development when compared with parental care or other nonparental care, as well as improved social competence (compared with parental care) and reduced attention problems (compared with other nonparental care). In contrast, compared with attendance at pre-kindergarten or other center-based care, Head Start attendance was not associated with cognitive gains but with improved social competence and reduced attention and externalizing behavior problems (compared with attendance at other center-based care). These associations were not moderated by child gender or race/ethnicity. PMID:21244155

Head Start and urban children's school readiness: a birth cohort study in 18 cities.

PubMed

Zhai, Fuhua; Brooks-Gunn, Jeanne; Waldfogel, Jane

2011-01-01

We used longitudinal data from a birth cohort study, the Fragile Families and Child Wellbeing Study, to investigate the links between Head Start and school readiness in a large and diverse sample of urban children at age 5 (N = 2,803; 18 cities). We found that Head Start attendance was associated with enhanced cognitive ability and social competence and reduced attention problems but not reduced internalizing or externalizing behavior problems. These findings were robust to model specifications (including models with city-fixed effects and propensity-scoring matching). Furthermore, the effects of Head Start varied by the reference group. Head Start was associated with improved cognitive development when compared with parental care or other nonparental care, as well as improved social competence (compared with parental care) and reduced attention problems (compared with other nonparental care). In contrast, compared with attendance at pre-kindergarten or other center-based care, Head Start attendance was not associated with cognitive gains but with improved social competence and reduced attention and externalizing behavior problems (compared with attendance at other center-based care). These associations were not moderated by child gender or race/ethnicity.

Radial stability of anisotropic strange quark stars

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

Arbañil, José D.V.; Malheiro, M., E-mail: jose.arbanil@upn.pe, E-mail: malheiro@ita.br

The influence of the anisotropy in the equilibrium and stability of strange stars is investigated through the numerical solution of the hydrostatic equilibrium equation and the radial oscillation equation, both modified from their original version to include this effect. The strange matter inside the quark stars is described by the MIT bag model equation of state. For the anisotropy two different kinds of local anisotropic σ = p {sub t} − p {sub r} are considered, where p {sub t} and p {sub r} are respectively the tangential and the radial pressure: one that is null at the star's surfacemore » defined by p {sub r} ( R ) = 0, and one that is nonnull at the surface, namely, σ {sub s} = 0 and σ {sub s} {sub ≠} {sub 0}. In the case σ {sub s} = 0, the maximum mass value and the zero frequency of oscillation are found at the same central energy density, indicating that the maximum mass marks the onset of the instability. For the case σ {sub s} {sub ≠} {sub 0}, we show that the maximum mass point and the zero frequency of oscillation coincide in the same central energy density value only in a sequence of equilibrium configurations with the same value of σ {sub s} . Thus, the stability star regions are determined always by the condition dM / d ρ {sub c} {sub >} {sub 0} only when the tangential pressure is maintained fixed at the star surface's p {sub t} ( R ). These results are also quite important to analyze the stability of other anisotropic compact objects such as neutron stars, boson stars and gravastars.« less

VizieR Online Data Catalog: ATLAS3D Project. XXX (McDermid+, 2015)

NASA Astrophysics Data System (ADS)

McDermid, R. M.; Alatalo, K.; Blitz, L.; Bournaud, F.; Bureau, M.; Cappellari, M.; Crocker, A. F.; Davies, R. L.; Davis, T. A.; De Zeeuw, P. T.; Duc, P.-A.; Emsellem, E.; Khochfar, S.; Krajnovic, D.; Kuntschner, H.; Morganti, R.; Naab, T.; Oosterloo, T.; Sarzi, M.; Scott, N.; Serra, P.; Weijmans, A.-M.; Young, L. M.

2015-09-01

We present the stellar population content of early-type galaxies from the ATLAS3D survey. Using spectra integrated within apertures covering up to one effective radius, we apply two methods: one based on measuring line-strength indices and applying single stellar population (SSP) models to derive SSP-equivalent values of stellar age, metallicity, and alpha enhancement; and one based on spectral fitting to derive non-parametric star formation histories, mass-weighted average values of age, metallicity, and half-mass formation time-scales. Using homogeneously derived effective radii and dynamically determined galaxy masses, we present the distribution of stellar population parameters on the Mass Plane (MJAM, σe, Rmaje), showing that at fixed mass, compact early-type galaxies are on average older, more metal-rich, and more alpha-enhanced than their larger counterparts. From non-parametric star formation histories, we find that the duration of star formation is systematically more extended in lower mass objects. Assuming that our sample represents most of the stellar content of today's local Universe, approximately 50 percent of all stars formed within the first 2Gyr following the big bang. Most of these stars reside today in the most massive galaxies (>1010.5M⊙), which themselves formed 90 percent of their stars by z~2. The lower mass objects, in contrast, have formed barely half their stars in this time interval. Stellar population properties are independent of environment over two orders of magnitude in local density, varying only with galaxy mass. In the highest density regions of our volume (dominated by the Virgo cluster), galaxies are older, alpha-enhanced, and have shorter star formation histories with respect to lower density regions. (4 data files).

Coupling hydrodynamics and radiation calculations for star-jet interactions in active galactic nuclei

NASA Astrophysics Data System (ADS)

de la Cita, V. M.; Bosch-Ramon, V.; Paredes-Fortuny, X.; Khangulyan, D.; Perucho, M.

2016-06-01

Context. Stars and their winds can contribute to the non-thermal emission in extragalactic jets. Because of the complexity of jet-star interactions, the properties of the resulting emission are closely linked to those of the emitting flows. Aims: We simulate the interaction between a stellar wind and a relativistic extragalactic jet and use the hydrodynamic results to compute the non-thermal emission under different conditions. Methods: We performed relativistic axisymmetric hydrodynamical simulations of a relativistic jet interacting with a supersonic, non-relativistic stellar wind. We computed the corresponding streamlines out of the simulation results and calculated the injection, evolution, and emission of non-thermal particles accelerated in the jet shock, focusing on electrons or e±-pairs. Several cases were explored, considering different jet-star interaction locations, magnetic fields, and observer lines of sight. The jet luminosity and star properties were fixed, but the results are easily scalable when these parameters are changed. Results: Individual jet-star interactions produce synchrotron and inverse Compton emission that peaks from X-rays to MeV energies (depending on the magnetic field), and at ~100-1000 GeV (depending on the stellar type), respectively. The radiation spectrum is hard in the scenarios explored here as a result of non-radiative cooling dominance, as low-energy electrons are efficiently advected even under relatively high magnetic fields. Interactions of jets with cold stars lead to an even harder inverse Compton spectrum because of the Klein-Nishina effect in the cross section. Doppler boosting has a strong effect on the observer luminosity. Conclusions: The emission levels for individual interactions found here are in the line of previous, more approximate, estimates, strengthening the hypothesis that collective jet-star interactions could significantly contribute at high energies under efficient particle acceleration.

Further X-Ray Observations of EXO 0748-676 in Quiescence: Evidence for a Cooling Neutron Star Crust

DTIC Science & Technology

2010-07-01

Satellite Date ∆t Pow. frac. kT∞eff FX F th bol Lbol Red. χ 2 (days) (%) (eV) (d.o.f.) Swift† 2008-09-28 – 2008-10-07 4.9 10 fix 123.7± 5.4 1.31± 0.22 1.53...fixed. The quoted errors represent 90% confidence levels. FX represents the 0.5–10 keV total model flux and F thbol gives the 0.01–100 keV NSATMOS...Miller J. M., Wijnands R., 2010, submitted to ApJ Campana S., 2003, preprint ( astro -ph/0311212) Campana S., Colpi M., Mereghetti S., Stella L

New Basal Insulins: a Clinical Perspective of Their Use in the Treatment of Type 2 Diabetes and Novel Treatment Options Beyond Basal Insulin.

PubMed

Frias, Patrick F; Frias, Juan Pablo

2017-08-18

The purpose of this review was to review advances in basal insulin formulations and new treatment options for patients with type 2 diabetes not achieving glycemic targets despite optimized basal insulin therapy. Advances in basal insulin formulations have resulted in products with increasingly favorable pharmacokinetic and pharmacodynamic properties, including flatter, peakless action profiles, less inter- and intra-patient variability, and longer duration of activity. These properties have translated to significantly reduced risk of hypoglycemia (particularly during the night) compared with previous generation basal insulins. When optimized basal insulin therapy is not sufficient to obtain or maintain glycemic goals, various options exist to improve glycemic control, including intensification of insulin therapy with the addition of prandial insulin or changing to pre-mixed insulin and, more recently, the addition of a GLP-1 receptor agonist, either as a separate injection or as a component of one of the new fixed-ratio combinations of a basal insulin and GLP-1 RA. New safer and often more convenient basal insulins and fixed ratio combinations containing basal insulin (and GLP-1 receptor agonist) are available today for patients with type 2 diabetes not achieving glycemic goals. Head-to-head studies comparing the latest generation basal insulins are underway, and future studies assessing the fixed-ratio combinations will be important to better understand their differentiating features.

Multispectral image-fused head-tracked vision system (HTVS) for driving applications

NASA Astrophysics Data System (ADS)

Reese, Colin E.; Bender, Edward J.

2001-08-01

Current military thermal driver vision systems consist of a single Long Wave Infrared (LWIR) sensor mounted on a manually operated gimbal, which is normally locked forward during driving. The sensor video imagery is presented on a large area flat panel display for direct view. The Night Vision and Electronics Sensors Directorate and Kaiser Electronics are cooperatively working to develop a driver's Head Tracked Vision System (HTVS) which directs dual waveband sensors in a more natural head-slewed imaging mode. The HTVS consists of LWIR and image intensified sensors, a high-speed gimbal, a head mounted display, and a head tracker. The first prototype systems have been delivered and have undergone preliminary field trials to characterize the operational benefits of a head tracked sensor system for tactical military ground applications. This investigation will address the advantages of head tracked vs. fixed sensor systems regarding peripheral sightings of threats, road hazards, and nearby vehicles. An additional thrust will investigate the degree to which additive (A+B) fusion of LWIR and image intensified sensors enhances overall driving performance. Typically, LWIR sensors are better for detecting threats, while image intensified sensors provide more natural scene cues, such as shadows and texture. This investigation will examine the degree to which the fusion of these two sensors enhances the driver's overall situational awareness.

Star sub-pixel centroid calculation based on multi-step minimum energy difference method

NASA Astrophysics Data System (ADS)

Wang, Duo; Han, YanLi; Sun, Tengfei

2013-09-01

The star's centroid plays a vital role in celestial navigation, star images which be gotten during daytime, due to the strong sky background, have a low SNR, and the star objectives are nearly submerged in the background, takes a great trouble to the centroid localization. Traditional methods, such as a moment method, weighted centroid calculation method is simple but has a big error, especially in the condition of a low SNR. Gaussian method has a high positioning accuracy, but the computational complexity. Analysis of the energy distribution in star image, a location method for star target centroids based on multi-step minimum energy difference is proposed. This method uses the linear superposition to narrow the centroid area, in the certain narrow area uses a certain number of interpolation to pixels for the pixels' segmentation, and then using the symmetry of the stellar energy distribution, tentatively to get the centroid position: assume that the current pixel is the star centroid position, and then calculates and gets the difference of the sum of the energy which in the symmetric direction(in this paper we take the two directions of transverse and longitudinal) and the equal step length(which can be decided through different conditions, the paper takes 9 as the step length) of the current pixel, and obtain the centroid position in this direction when the minimum difference appears, and so do the other directions, then the validation comparison of simulated star images, and compare with several traditional methods, experiments shows that the positioning accuracy of the method up to 0.001 pixel, has good effect to calculate the centroid of low SNR conditions; at the same time, uses this method on a star map which got at the fixed observation site during daytime in near-infrared band, compare the results of the paper's method with the position messages which were known of the star, it shows that :the multi-step minimum energy difference method achieves a better effect.

The Impact of Star Formation Histories on Stellar Mass Estimation: Implications from the Local Group Dwarf Galaxies

NASA Astrophysics Data System (ADS)

Zhang, Hong-Xin; Puzia, Thomas H.; Weisz, Daniel R.

2017-11-01

Building on the relatively accurate star formation histories (SFHs) and metallicity evolution of 40 Local Group (LG) dwarf galaxies derived from resolved color-magnitude diagram modeling, we carried out a comprehensive study of the influence of SFHs, metallicity evolution, and dust extinction on the UV-to-near-IR color-mass-to-light ratio (color-{log}{{{\\Upsilon }}}\\star (λ)) distributions and M ⋆ estimation of local universe galaxies. We find that (1) the LG galaxies follow color-{log}{{{\\Upsilon }}}\\star (λ) relations that fall in between the ones calibrated by previous studies; (2) optical color-{log}{{{\\Upsilon }}}\\star (λ) relations at higher [M/H] are generally broader and steeper; (3) the SFH “concentration” does not significantly affect the color-{log}{{{\\Upsilon }}}\\star (λ) relations; (4) light-weighted ages < {age}{> }λ and metallicities < [{{M}}/{{H}}]{> }λ together constrain {log}{{{\\Upsilon }}}\\star (λ) with uncertainties ranging from ≲0.1 dex for the near-IR up to 0.2 dex for the optical passbands; (5) metallicity evolution induces significant uncertainties to the optical but not near-IR {{{\\Upsilon }}}\\star (λ) at a given < {age}{> }λ and < [{{M}}/{{H}}]{> }λ ; (6) the V band is the ideal luminance passband for estimating {{{\\Upsilon }}}\\star (λ) from single colors, because the combinations of {{{\\Upsilon }}}\\star (V) and optical colors such as B - V and g - r exhibit the weakest systematic dependences on SFHs, metallicities, and dust extinction; and (7) without any prior assumption on SFHs, M ⋆ is constrained with biases ≲0.3 dex by the optical-to-near-IR SED fitting. Optical passbands alone constrain M ⋆ with biases ≲0.4 dex (or ≲0.6 dex) when dust extinction is fixed (or variable) in SED fitting. SED fitting with monometallic SFH models tends to underestimate M ⋆ of real galaxies. M ⋆ tends to be overestimated (or underestimated) at the youngest (or oldest) < {age}{> }{mass}.

The Lesser Role of Starbursts in Star Formation at z = 2

NASA Astrophysics Data System (ADS)

Rodighiero, G.; Daddi, E.; Baronchelli, I.; Cimatti, A.; Renzini, A.; Aussel, H.; Popesso, P.; Lutz, D.; Andreani, P.; Berta, S.; Cava, A.; Elbaz, D.; Feltre, A.; Fontana, A.; Förster Schreiber, N. M.; Franceschini, A.; Genzel, R.; Grazian, A.; Gruppioni, C.; Ilbert, O.; Le Floch, E.; Magdis, G.; Magliocchetti, M.; Magnelli, B.; Maiolino, R.; McCracken, H.; Nordon, R.; Poglitsch, A.; Santini, P.; Pozzi, F.; Riguccini, L.; Tacconi, L. J.; Wuyts, S.; Zamorani, G.

2011-10-01

Two main modes of star formation are know to control the growth of galaxies: a relatively steady one in disk-like galaxies, defining a tight star formation rate (SFR)-stellar mass sequence, and a starburst mode in outliers to such a sequence which is generally interpreted as driven by merging. Such starburst galaxies are rare but have much higher SFRs, and it is of interest to establish the relative importance of these two modes. PACS/Herschel observations over the whole COSMOS and GOODS-South fields, in conjunction with previous optical/near-IR data, have allowed us to accurately quantify for the first time the relative contribution of the two modes to the global SFR density in the redshift interval 1.5 < z < 2.5, i.e., at the cosmic peak of the star formation activity. The logarithmic distributions of galaxy SFRs at fixed stellar mass are well described by Gaussians, with starburst galaxies representing only a relatively minor deviation that becomes apparent for SFRs more than four times higher than on the main sequence. Such starburst galaxies represent only 2% of mass-selected star-forming galaxies and account for only 10% of the cosmic SFR density at z ~ 2. Only when limited to SFR > 1000 M sun yr-1, off-sequence sources significantly contribute to the SFR density (46% ± 20%). We conclude that merger-driven starbursts play a relatively minor role in the formation of stars in galaxies, whereas they may represent a critical phase toward the quenching of star formation and morphological transformation in galaxies.

Kepler Mission: A Wide-FOV Photometer Designed to Determine the Frequency of Earth-Size and Larger Planets Around Solar-like stars

NASA Technical Reports Server (NTRS)

Borucki, William; Koch, David; Lissauer, Jack; Basri, Gibor; Caldwell, John; Cochran, William; Dunham, Edward W.; Gilliland, Ronald; Jenkins, Jon M.; Caldwell, Douglas;

SU-F-P-36: Automation of Linear Accelerator Star Shot Measurement with Advanced XML Scripting and Electronic Portal Imaging Device

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

Nguyen, N; Knutson, N; Schmidt, M

Purpose: To verify a method used to automatically acquire jaw, MLC, collimator and couch star shots for a Varian TrueBeam linear accelerator utilizing Developer Mode and an Electronic Portal Imaging Device (EPID). Methods: An XML script was written to automate motion of the jaws, MLC, collimator and couch in TrueBeam Developer Mode (TBDM) to acquire star shot measurements. The XML script also dictates MV imaging parameters to facilitate automatic acquisition and recording of integrated EPID images. Since couch star shot measurements cannot be acquired using a combination of EPID and jaw/MLC collimation alone due to a fixed imager geometry, amore » method utilizing a 5mm wide steel ruler placed on the table and centered within a 15×15cm2 open field to produce a surrogate of the narrow field aperture was investigated. Four individual star shot measurements (X jaw, Y jaw, MLC and couch) were obtained using our proposed as well as traditional film-based method. Integrated EPID images and scanned measurement films were analyzed and compared. Results: Star shot (X jaw, Y jaw, MLC and couch) measurements were obtained in a single 5 minute delivery using the TBDM XML script method compared to 60 minutes for equivalent traditional film measurements. Analysis of the images and films demonstrated comparable isocentricity results, agreeing within 0.3mm of each other. Conclusion: The presented automatic approach of acquiring star shot measurements using TBDM and EPID has proven to be more efficient than the traditional film approach with equivalent results.« less

Dynamics of influence on hierarchical structures

NASA Astrophysics Data System (ADS)

Fotouhi, Babak; Rabbat, Michael G.

2013-08-01

Dichotomous spin dynamics on a pyramidal hierarchical structure (the Bethe lattice) are studied. The system embodies a number of classes, where a class comprises nodes that are equidistant from the root (head node). Weighted links exist between nodes from the same and different classes. The spin (hereafter state) of the head node is fixed. We solve for the dynamics of the system for different boundary conditions. We find necessary conditions so that the classes eventually repudiate or acquiesce in the state imposed by the head node. The results indicate that to reach unanimity across the hierarchy, it suffices that the bottommost class adopts the same state as the head node. Then the rest of the hierarchy will inevitably comply. This also sheds light on the importance of mass media as a means of synchronization between the topmost and bottommost classes. Surprisingly, in the case of discord between the head node and the bottommost classes, the average state over all nodes inclines towards that of the bottommost class regardless of the link weights and intraclass configurations. Hence the role of the bottommost class is signified.

Direct Measurement of Dust Attenuation in z approx. 1.5 Star-Forming Galaxies from 3D-HST: Implications for Dust Geometry and Star Formation Rates

NASA Technical Reports Server (NTRS)

Price, Sedona H.; Kriek, Mariska; Brammer, Gabriel B; Conroy, Charlie; Schreiber, Natascha M. Foerster; Franx, Marijn; Fumagalli, Mattia; Lundren, Britt; Momcheva, Ivelina; Nelson, Erica J.;

A fixed false alarm probability figure of merit for gravitational wave detectors

NASA Astrophysics Data System (ADS)

Wąs, M.; Kalmus, P.; Leong, J. R.; Adams, T.; Leroy, N.; Macleod, D. M.; Pankow, C.; Robinet, F.

2014-04-01

Performance of gravitational wave (GW) detectors can be characterized by several figures of merit (FOMs) which are used to guide the detector’s commissioning and operations, and to gauge astrophysical sensitivity. One key FOM is the range in Mpc, averaged over orientation and sky location, at which a GW signal from binary neutron star inspiral and coalescence would have a signal-to-noise ratio (SNR) of 8 in a single detector. This fixed-SNR approach does not accurately reflect the effects of transient noise (glitches), which can severely limit the detectability of transient GW signals expected from a variety of astrophysical sources. We propose a FOM based instead on a fixed false-alarm probability (FAP). This is intended to give a more realistic estimate of the detectable GW transient range including the effect of glitches. Our approach applies equally to individual interferometers or a network of interferometers. We discuss the advantages of the fixed-FAP approach, present examples from a prototype implementation, and discuss the impact it has had on the recent commissioning of the GW detector GEO 600.

The impact of Hipparcos star-fixing extends to life's evolution

NASA Astrophysics Data System (ADS)

1997-05-01

"ESA's Hipparcos brings the greatest step forward in star measurements since Tycho Brahe," Bonnet says. "When the Danish astronomer died in 1601, the German astronomer Johannes Kepler inherited his careful observations. Kepler used them to discover the laws of the motions of planets, and paved the way for Isaac Newton's gravitational theory. Now we have another multinational success story from European astronomy". "Hipparcos began as an imaginative French concept to chart the stars by satellite," Bonnet continues. "ESA adopted the idea and many astronomers in our member states collaborated in the mission. A hundred-fold improvement in the accuracy of star positions may already alter the size of the Universe and the ages of stars. So don't be surprised if the results from Hipparcos are as revolutionary as Tycho Brahe's, in their impact on our knowledge of the cosmos." The study of the Earth itself will benefit from the new star data. Wobbles of the Earth and variations in its rate of rotation can now be measured far more accurately. The ozone layer will be monitored by ESA's Envisat environmental mission, by looking for chemical alterations in the light from 1000 Hipparcos stars, when seen on lines of sight slanting through the atmosphere. Even the erratic evolution of life on Earth may make more sense, as Hipparcos picks out stars that passed close enough to cause trouble here. Reliable identifications of stars heading towards or away from our vicinity were impossible before Hipparcos. The satellite measured shifts in the directions of stars in the sky with such high precision that astronomers can now pick out those few stars that scarcely change their bearings. Such stars are probably moving almost directly towards or away from us. A US-European team, led by Robert Preston at the Jet Propulsion Laboratory in California, used Hipparcos to search for nearby stars with very small shifts in position. They were, or will be, passers-by. Gliese 710, an inconspicuous star in the constellation Ophiuchus, is currently 63 light-years away and approaching at about 14 kilometres per second. From the Hipparcos data, it will pass within about one light-year, one million years from now. Joan Garcia-Sanchez, a doctoral student in Preston's team, identifies Gliese 710 in one of the scientific posters that display Hipparcos results in Venice. Garcia-Sanchez has found evidence that Gliese 710 is today moving more slowly towards the Sun than it was several decades ago. That may mean it is orbiting around another star, so far unidentified. If so, the closest distance to which Gliese 710 will approach may be nearer or farther than in the team's initial estimate. The stars of the Alpha Centauri system, at 4 light-years, are the nearest at present. Several stars investigated by Preston and his colleagues will come within 3 light-years during the next 8,500,000 years. Others have already passed by during a similar time-span and are now travelling away from us. "A star coming too near could put the Earth at risk," Bob Preston explains. "It might dislodge comets from a swarm that surrounds the Sun in the Oort Cloud, and send them into the inner Solar System. Some comets could then collide with our planet. The fossils tell us of past disasters, in extinctions of many species, and we hope to identify culprits among stars now hurrying away from the scene. The theory isn't new, but only now can we check it, thanks to the amazing precision of Hipparcos." Uncertainty about the timing of the stellar visits arises from inadequate information about the speed of approach or recession. That is measured from ground-based observatories, by shifts in the wavelengths of light (blueshifts and redshifts). A team led by Dave Latham at the Center for Astrophysics in Cambridge, Massachusetts, is busy making fresh observations to improve the ground-based data on the visitors, past and future. The Hipparcos Catalogue and the wider Universe Hipparcos results fill large catalogues due for release to the world's astronomers via the Internet and in CD-ROMs early in June, and in 16 printed volumes soon afterwards. These are results of four years of space observations, 1989-93, and a further three years of intensive computation. The Hipparcos Catalogue echoes the name of Hipparchus, who founded astrometry in ancient Greece. It gives precise data on 118,000 stars. A million stars, logged with lesser but still unprecedented ccuracy, comprise the Tycho Catalogue, named after Tycho Brahe. The role of Albert Einstein's theory of gravity illustrates the extraordinary accuracy of the Hipparcos Catalogue. General Relativity predicts a deflection of starlight by the Sun's gravity. Hitherto this was confirmed only with objects seen within a degree or two of the edge of the Sun, where the effect is strongest. Hipparcos was sensitive to the bending of light-rays even in directions at right angles to the Sun. If the computations had ignored General Relativity the star-fixing would be less accurate. Conversely, Einstein's predictions are found to be correct to within one part in a thousand. As well as the positions, distances and motions of many stars, the Hipparcos Catalogue includes unprecedented surveys of double and variable stars. Hipparcos observed 24,000 double stars in the Hipparcos Catalogue, of which 10,000 were not previously known to be double. Frequent observations, over the four years of the space operations, monitored the changes in brightness of 12,000 known variable stars, and discovered 8000 more. The stars charted by Hipparcos are relatively close, compared with the galaxies. Eleven teams of astronomers have cooperated in linking them to the wider cosmos, defined in the International Celestial Reference Frame. They matched Hipparcos stars to galaxies near the lines of sight, to the major photographic surveys of the sky, and to the sharp observations in long-range astronomy that come from widely spaced radio instruments and the Hubble Space Telescope. Radio astronomers will henceforward be able to correct any mismatch, by comparing nearby radio sources in the Hipparcos Catalogue with the positions of distant quasars. Jean Kovalevsky of the CJte d'Azur Observatory in Grasse, France, coordinated this work of uniting Hipparcos results with the cosmos in general. He is also the leader of the consortium called FAST (Fundamental Astronomy by Space Techniques) which is one of two multinational teams that worked in parallel to generate the basic Hipparcos Catalogue. "We have related the stars of Hipparcos to the whole Universe of galaxies and quasars, to better than two tenths of a millionth of a degree," Kovalevsky reports. "We have also got rid of a possible rotation of the system of Hipparcos stars, to more than twice that precision. And the wide Universe gives us a more reliable reference frame for the sky and the stars than our spinning, wobbling and orbiting planet has ever provided." Among the astronomical space missions already adopting Hipparcos data for better aiming is ESA's Infrared Space Observatory ISO. The forthcoming X-ray astronomy missions, NASA's AXAF and ESA's XMM, will rely on Hipparcos when searching the sky. Hipparcos stars will also guide deep space probes, including the NASA-ESA Cassini/Huygens mission to Saturn and Titan, and ESA's Rosetta mission to Comet Wirtanen. The Tycho project progresses from 1,000,000 to 3,000,000 stars The Tycho Catalogue gives the positions of many more stars, so although its accuracy is about one-tenth as good as the Hipparcos Catalogue's, it is the more generous source of greatly improved data for the world's astronomers. Plotting and characterizing eight times as many stars as the Hipparcos Catalogue, the Tycho Catalogue offers a comprehensive survey of the stars around the Sun. It includes 99.9 per cent of stars down to magnitude 10, which means stars 100 times fainter than the unaided human eye can normally see. Russian and German astronomers are now comparing the Tycho results on a million stars with positions of the same stars observed from the ground during the past 100 years, to measure their motions across the sky. The Danish astronomer Erik Hog is a worthy heir of Tycho Brahe. He adopted a star mapper, installed in Hipparcos for checking the telescope's aim, as an additional source of astrometric data. From Copenhagen University Observatory he led the multinational Tycho Data Analysis Consortium (TDAC) which produced the Tycho Catalogue. "A million million bits of data came from our star mapper in Hipparcos," Hog remarks. "We nearly drowned in the torrent when we started. So we limited the Tycho Catalogue to one million stars, in order to keep up with the work on the Hipparcos Catalogue. With more experience and faster computers, and based on the Hipparcos and Tycho Catalogues, we've started work on a Second Tycho Catalogue of three million stars. We hope to have it ready by 1999."

Automated Extraction of Formalin-Fixed, Paraffin-Embedded Tissue for High-Risk Human Papillomavirus Testing of Head and Neck Squamous Cell Carcinomas Using the Roche Cobas 4800 System.

PubMed

Kerr, Darcy A; Sweeney, Brenda; Arpin, Ronald N; Ring, Melissa; Pitman, Martha B; Wilbur, David C; Faquin, William C

2016-08-01

-Testing for high-risk human papillomavirus (HR-HPV) in head and neck squamous cell carcinomas (HNSCCs) is important for both prognostication and clinical management. Several testing platforms are available for HR-HPV; however, effective alternative automated approaches are needed. -To assess the performance of the automated Roche cobas 4800 HPV real-time polymerase chain reaction-based system on formalin-fixed, paraffin-embedded HNSCC specimens and compare results with standard methods of in situ hybridization (ISH) and p16 immunohistochemistry. -Formalin-fixed, paraffin-embedded samples of HNSCC were collected from archival specimens in the Department of Pathology, Massachusetts General Hospital (Boston), and prepared using the automated system by deparaffinization and dehydration followed by tissue lysis. Samples were integrated into routine cervical cytology testing runs by cobas. Corresponding formalin-fixed, paraffin-embedded samples were evaluated for HR-HPV by ISH and p16 by immunohistochemistry. Discrepant cases were adjudicated by polymerase chain reaction. -Sixty-two HNSCC samples were analyzed using the automated cobas system, ISH, and immunohistochemistry. Fifty-two percent (n = 32 of 62) of formalin-fixed, paraffin-embedded tumors were positive for HR-HPV by cobas. Eighty-eight percent (n = 28 of 32) of cases were the HPV 16 subtype and 12% (n = 4 of 32) were other HR-HPV subtypes. Corresponding testing with ISH was concordant in 92% (n = 57 of 62) of cases. Compared with the adjudication polymerase chain reaction standard, there were 3 false-positive cases by cobas. -Concordance in HNSCC HR-HPV status between cobas and ISH was more than 90%. The cobas demonstrated a sensitivity of 100% and a specificity of 91% for detection of HR-HPV. Advantages favoring cobas include its automation, cost efficiency, objective results, and ease of performance.

Dependence of auditory spatial updating on vestibular, proprioceptive, and efference copy signals

PubMed Central

Genzel, Daria; Firzlaff, Uwe; Wiegrebe, Lutz

2016-01-01

Humans localize sounds by comparing inputs across the two ears, resulting in a head-centered representation of sound-source position. When the head moves, information about head movement must be combined with the head-centered estimate to correctly update the world-centered sound-source position. Spatial updating has been extensively studied in the visual system, but less is known about how head movement signals interact with binaural information during auditory spatial updating. In the current experiments, listeners compared the world-centered azimuthal position of two sound sources presented before and after a head rotation that depended on condition. In the active condition, subjects rotated their head by ∼35° to the left or right, following a pretrained trajectory. In the passive condition, subjects were rotated along the same trajectory in a rotating chair. In the cancellation condition, subjects rotated their head as in the active condition, but the chair was counter-rotated on the basis of head-tracking data such that the head effectively remained fixed in space while the body rotated beneath it. Subjects updated most accurately in the passive condition but erred in the active and cancellation conditions. Performance is interpreted as reflecting the accuracy of perceived head rotation across conditions, which is modeled as a linear combination of proprioceptive/efference copy signals and vestibular signals. Resulting weights suggest that auditory updating is dominated by vestibular signals but with significant contributions from proprioception/efference copy. Overall, results shed light on the interplay of sensory and motor signals that determine the accuracy of auditory spatial updating. PMID:27169504

Dependence of auditory spatial updating on vestibular, proprioceptive, and efference copy signals.

PubMed

Genzel, Daria; Firzlaff, Uwe; Wiegrebe, Lutz; MacNeilage, Paul R

2016-08-01

Humans localize sounds by comparing inputs across the two ears, resulting in a head-centered representation of sound-source position. When the head moves, information about head movement must be combined with the head-centered estimate to correctly update the world-centered sound-source position. Spatial updating has been extensively studied in the visual system, but less is known about how head movement signals interact with binaural information during auditory spatial updating. In the current experiments, listeners compared the world-centered azimuthal position of two sound sources presented before and after a head rotation that depended on condition. In the active condition, subjects rotated their head by ∼35° to the left or right, following a pretrained trajectory. In the passive condition, subjects were rotated along the same trajectory in a rotating chair. In the cancellation condition, subjects rotated their head as in the active condition, but the chair was counter-rotated on the basis of head-tracking data such that the head effectively remained fixed in space while the body rotated beneath it. Subjects updated most accurately in the passive condition but erred in the active and cancellation conditions. Performance is interpreted as reflecting the accuracy of perceived head rotation across conditions, which is modeled as a linear combination of proprioceptive/efference copy signals and vestibular signals. Resulting weights suggest that auditory updating is dominated by vestibular signals but with significant contributions from proprioception/efference copy. Overall, results shed light on the interplay of sensory and motor signals that determine the accuracy of auditory spatial updating. Copyright © 2016 the American Physiological Society.

Concurrent 3-D sonifications enable the head-up monitoring of two interrelated aircraft navigation instruments.

PubMed

Towers, John; Burgess-Limerick, Robin; Riek, Stephan

2014-12-01

The aim of this study was to enable the head-up monitoring of two interrelated aircraft navigation instruments by developing a 3-D auditory display that encodes this navigation information within two spatially discrete sonifications. Head-up monitoring of aircraft navigation information utilizing 3-D audio displays, particularly involving concurrently presented sonifications, requires additional research. A flight simulator's head-down waypoint bearing and course deviation instrument readouts were conveyed to participants via a 3-D auditory display. Both readouts were separately represented by a colocated pair of continuous sounds, one fixed and the other varying in pitch, which together encoded the instrument value's deviation from the norm. Each sound pair's position in the listening space indicated the left/right parameter of its instrument's readout. Participants' accuracy in navigating a predetermined flight plan was evaluated while performing a head-up task involving the detection of visual flares in the out-of-cockpit scene. The auditory display significantly improved aircraft heading and course deviation accuracy, head-up time, and flare detections. Head tracking did not improve performance by providing participants with the ability to orient potentially conflicting sounds, suggesting that the use of integrated localizing cues was successful. Conclusion: A supplementary 3-D auditory display enabled effective head-up monitoring of interrelated navigation information normally attended to through a head-down display. Pilots operating aircraft, such as helicopters and unmanned aerial vehicles, may benefit from a supplementary auditory display because they navigate in two dimensions while performing head-up, out-of-aircraft, visual tasks.

Do the radial head prosthesis components fit with the anatomical structures of the proximal radioulnar joint?

PubMed

Wegmann, Kilian; Hain, Moritz K; Ries, Christian; Neiss, Wolfram F; Müller, Lars P; Burkhart, Klaus J

2015-09-01

The fitting accuracy of radial head components has been investigated in the capitulo-radial joint, and reduced contact after prosthetic replacement of the radial head has been observed. The kinematics of the proximal radioulnar joint (PRUJ) are affected by radial head arthroplasty as well, but have not yet been investigated in this regard. The elbow joints of 60 upper extremities of formalin-fixed body donors were disarticulated to obtain a good view of the PRUJ. Each specimen was mounted on the examining table and radial head position in the native PRUJ was assessed in neutral position, full pronation, and full supination. Measurements were repeated after implantation of mono- and bi-polar prostheses. Analysis of the distribution of the joint contacts in the compartments showed significant differences after radial head replacement. In comparison to the native joint, after bipolar and monopolar radial head replacement, the physiological shift of the proximal radius was altered. The physiological shift of the joint contact of the radial head from anterior to posterior during forearm rotation that was found in the native joint in our cadaver model was not observed after prosthetic replacement. With higher conformity and physiological kinematic of radial head prostheses, possibly lower shear forces and lower contact pressures would be generated. The tested radial head prostheses do not replicate the physiological kinematics of the radial head. Further development in the prosthesis design has to be made. The meticulous reconstruction of the annular ligament seems to be of importance to increase joint contact.

Endoscopic intracranial surgery enhanced by electromagnetic-guided neuronavigation in children.

PubMed

Hermann, Elvis J; Esmaeilzadeh, Majid; Ertl, Philipp; Polemikos, Manolis; Raab, Peter; Krauss, Joachim K

2015-08-01

Navigated intracranial endoscopy with conventional technique usually requires sharp head fixation. In children, especially in those younger than 1 year of age and in older children with thin skulls due to chronic hydrocephalus, sharp head fixation is not possible. Here, we studied the feasibility, safety, and accuracy of electromagnetic (EM)-navigated endoscopy in a series of children, obviating the need of sharp head fixation. Seventeen children (ten boys, seven girls) between 12 days and 16.8 years (mean age 4.3 years; median 14 months) underwent EM-navigated intracranial endoscopic surgery based on 3D MR imaging of the head. Inclusion criteria for the study were intraventricular cysts, arachnoid cysts, aqueduct stenosis for endoscopic third ventriculostomy (ETV) with distorted ventricular anatomy, the need of biopsy in intraventricular tumors, and multiloculated hydrocephalus. A total of 22 endoscopic procedures were performed. Patients were registered for navigation by surface rendering in the supine position. After confirming accuracy, they were repositioned for endoscopic surgery with the head fixed slightly on a horseshoe headholder. EM navigation was performed using a flexible stylet introduced into the working channel of a rigid endoscope. Neuronavigation accuracy was checked for deviations measured in millimeters on screenshots after the referencing procedure and during surgery in the coronal (z = vertical), axial (x = mediolateral), and sagittal (y = anteroposterior) planes. EM-navigated endoscopy was feasible and safe. In all 17 patients, the aim of endoscopic surgery was achieved, except in one case in which a hemorrhage occurred, blurring visibility, and we proceeded with open surgery without complications for the patient. Navigation accuracy for extracranial markers such as the tragus, bregma, and nasion ranged between 1 and 2.5 mm. Accuracy for fixed anatomical structures like the optic nerve or the carotid artery varied between 2 and 4 mm, while there was a broader variance of accuracy at the target point of the cyst itself ranging between 2 and 9 mm. EM-navigated endoscopy in children is a safe and useful technique enhancing endoscopic intracranial surgery and obviating the need of sharp head fixation. It is a good alternative to the common opto-electric navigation system in this age group.

Space experiments on basic technologies for a space elevator using microsatellites

NASA Astrophysics Data System (ADS)

Yamagiwa, Yoshiki; Nohmi, Masahiro; Aoki, Yoshio; Momonoi, Yu; Nanba, Hirotaka; Aiga, Masanori; Kumao, Takeru; Watahiki, Masahito

2017-09-01

We attempt to verify two basic technologies required for a space elevator using microsatellites; the tether (cable) deployment technology and the climber operation along the tether in space. Tether deployment is performed by a CubeSat called STARS-C (Space Tethered Autonomous Robotic Satellite - Cube) which will be released from the Japanese experimental module Kibo on ISS early in 2017. STARS-C consists of a mother satellite (MS) and daughter satellite (DS) connected by a 100-m tether. Its mission is focused on the tether deployment for studying the tether dynamics during the deployment with the goal of improving the smoothness of such deployment in future tether missions including space elevator. The MS and DS have common subsystems, including power, communication, and command and data handling systems. They also have a tether unit with spool and reel mechanisms as a mission system. In addition, we have been designing the next-step microsatellite called STARS-E (Space Tethered Autonomous Robotic Satellite - Elevator) under a Grant-in-Aid for Scientific Research. STARS-E is a 500-mm size satellite intended to verify the climber operation in space. It consists of a MS and DS jointed by a 2-km tether, and a climber that moves along the tether. STARS-C was launched on December 9 in 2016 and will be performed its mission early in 2017. STARS-E is in the BBM phase, and some designs are currently being fixed.

EMERGE - an empirical model for the formation of galaxies since z ˜ 10

NASA Astrophysics Data System (ADS)

Moster, Benjamin P.; Naab, Thorsten; White, Simon D. M.

2018-06-01

We present EMERGE, an Empirical ModEl for the foRmation of GalaxiEs, describing the evolution of individual galaxies in large volumes from z ˜ 10 to the present day. We assign a star formation rate to each dark matter halo based on its growth rate, which specifies how much baryonic material becomes available, and the instantaneous baryon conversion efficiency, which determines how efficiently this material is converted to stars, thereby capturing the baryonic physics. Satellites are quenched following the delayed-then-rapid model, and they are tidally disrupted once their subhalo has lost a significant fraction of its mass. The model is constrained with observed data extending out to high redshift. The empirical relations are very flexible, and the model complexity is increased only if required by the data, assessed by several model selection statistics. We find that for the same final halo mass galaxies can have very different star formation histories. Galaxies that are quenched at z = 0 typically have a higher peak star formation rate compared to their star-forming counterparts. EMERGE predicts stellar-to-halo mass ratios for individual galaxies and introduces scatter self-consistently. We find that at fixed halo mass, passive galaxies have a higher stellar mass on average. The intracluster mass in massive haloes can be up to eight times larger than the mass of the central galaxy. Clustering for star-forming and quenched galaxies is in good agreement with observational constraints, indicating a realistic assignment of galaxies to haloes.

Effects of Extreme Obliquity Variations on the Habitability of Exoplanets

NASA Technical Reports Server (NTRS)

Armstrong, J. C.; Barnes, R.; Domagal-Goldman, S.; Breiner, J.; Quinn, T. R.; Meadows, V. S.

2014-01-01

We explore the impact of obliquity variations on planetary habitability in hypothetical systems with high mutual inclination. We show that large-amplitude, high-frequency obliquity oscillations on Earth-like exoplanets can suppress the ice-albedo feedback, increasing the outer edge of the habitable zone. We restricted our exploration to hypothetical systems consisting of a solar-mass star, an Earth-mass planet at 1 AU, and 1 or 2 larger planets. We verified that these systems are stable for 108 years with N-body simulations and calculated the obliquity variations induced by the orbital evolution of the Earth-mass planet and a torque from the host star. We ran a simplified energy balance model on the terrestrial planet to assess surface temperature and ice coverage on the planet's surface, and we calculated differences in the outer edge of the habitable zone for planets with rapid obliquity variations. For each hypothetical system, we calculated the outer edge of habitability for two conditions: (1) the full evolution of the planetary spin and orbit and (2) the eccentricity and obliquity fixed at their average values. We recovered previous results that higher values of fixed obliquity and eccentricity expand the habitable zone, but we also found that obliquity oscillations further expand habitable orbits in all cases. Terrestrial planets near the outer edge of the habitable zone may be more likely to support life in systems that induce rapid obliquity oscillations as opposed to fixed-spin planets. Such planets may be the easiest to directly characterize with space-borne telescopes.

Effects of extreme obliquity variations on the habitability of exoplanets.

PubMed

Armstrong, J C; Barnes, R; Domagal-Goldman, S; Breiner, J; Quinn, T R; Meadows, V S

2014-04-01

We explore the impact of obliquity variations on planetary habitability in hypothetical systems with high mutual inclination. We show that large-amplitude, high-frequency obliquity oscillations on Earth-like exoplanets can suppress the ice-albedo feedback, increasing the outer edge of the habitable zone. We restricted our exploration to hypothetical systems consisting of a solar-mass star, an Earth-mass planet at 1 AU, and 1 or 2 larger planets. We verified that these systems are stable for 10(8) years with N-body simulations and calculated the obliquity variations induced by the orbital evolution of the Earth-mass planet and a torque from the host star. We ran a simplified energy balance model on the terrestrial planet to assess surface temperature and ice coverage on the planet's surface, and we calculated differences in the outer edge of the habitable zone for planets with rapid obliquity variations. For each hypothetical system, we calculated the outer edge of habitability for two conditions: (1) the full evolution of the planetary spin and orbit and (2) the eccentricity and obliquity fixed at their average values. We recovered previous results that higher values of fixed obliquity and eccentricity expand the habitable zone, but we also found that obliquity oscillations further expand habitable orbits in all cases. Terrestrial planets near the outer edge of the habitable zone may be more likely to support life in systems that induce rapid obliquity oscillations as opposed to fixed-spin planets. Such planets may be the easiest to directly characterize with space-borne telescopes.

Multi-wavelength observations of the star forming region in L1616

NASA Astrophysics Data System (ADS)

Alcalá, J. M.; Wachter, S.; Covino, E.; Sterzik, M. F.; Durisen, R. H.; Freyberg, M. J.; Hoard, D. W.; Cooksey, K.

2004-03-01

We present the results of a multi-wavelength study of the star forming region in L1616. Our observations include ROSAT All-Sky Survey (RASS) and High Resolution Imager (HRI) X-ray observations, optical wide-field imaging and near-IR imaging data and optical long-slit and multi-object spectroscopic follow-up. 22 new low-mass pre-main sequence (PMS) stars are found to be distributed mainly to the East of the L1616 cometary cloud, in about a one-square-degree field. We find that the class-III infrared sources outnumber the class-II infrared sources by a factor of about three. The X-ray properties of the PMS stars in L1616 are quite similar to those of PMS stars detected in the Orion Nebula Cluster. The comparison of the position of the L1616 PMS stars in the HR diagram with theoretical PMS evolutionary tracks yields an average age of 1-2 Myr, with a very small age spread of about 1 Myr. Unlike the fossil star forming regions in Orion, L1616 appears to be a region of on-going star formation relatively far from the Orion A and B clouds. Given the small age spread, the spatial distribution of the PMS stars relative to the head of the cloud, as well as its cometary shape and high star formation efficiency, we conclude that the star formation in L1616 was most likely induced by a single event, the impact of the winds of the massive stars of the Orion OB association or a supernova explosion being the possible triggers. The Initial Mass Function (IMF) in L1616 is roughly consistent with that of the field in the mass range 0.3< M/M⊙ < 2.5. Several faint objects, detected in our optical images, are good candidates for young Brown Dwarfs (BDs). We might expect the number of BDs in L1616 to be intermediate between Taurus and the Trapezium. Based on observations carried out at the European Southern Observatory, La Silla, Chile under proposals numbers 56.E-0566 and 64.I-0355, and at the Calar Alto observatory.

A GRAND VIEW OF THE BIRTH OF 'HEFTY' STARS - 30 DORADUS NEBULA MONTAGE

NASA Technical Reports Server (NTRS)

2002-01-01

This picture, taken in visible light with the Hubble Space Telescope's Wide Field and Planetary Camera 2 (WFPC2), represents a sweeping view of the 30 Doradus Nebula. But Hubble's infrared camera - the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) - has probed deeper into smaller regions of this nebula to unveil the stormy birth of massive stars. The montages of images in the upper left and upper right represent this deeper view. Each square in the montages is 15.5 light-years (19 arcseconds) across. The brilliant cluster R136, containing dozens of very massive stars, is at the center of this image. The infrared and visible-light views reveal several dust pillars that point toward R136, some with bright stars at their tips. One of them, at left in the visible-light image, resembles a fist with an extended index finger pointing directly at R136. The energetic radiation and high-speed material emitted by the massive stars in R136 are responsible for shaping the pillars and causing the heads of some of them to collapse, forming new stars. The infrared montage at upper left is enlarged in an accompanying image. Credits for NICMOS montages: NASA/Nolan Walborn (Space Telescope Science Institute, Baltimore, Md.) and Rodolfo Barba' (La Plata Observatory, La Plata, Argentina) Credits for WFPC2 image: NASA/John Trauger (Jet Propulsion Laboratory, Pasadena, Calif.) and James Westphal (California Institute of Technology, Pasadena, Calif.)

Hyperon stars in a modified quark meson coupling model

NASA Astrophysics Data System (ADS)

Mishra, R. N.; Sahoo, H. S.; Panda, P. K.; Barik, N.; Frederico, T.

2016-09-01

We determine the equation of state (EOS) of nuclear matter with the inclusion of hyperons in a self-consistent manner by using a modified quark meson coupling model where the confining interaction for quarks inside a baryon is represented by a phenomenological average potential in an equally mixed scalar-vector harmonic form. The hadron-hadron interaction in nuclear matter is then realized by introducing additional quark couplings to σ ,ω , and ρ mesons through mean-field approximations. The effect of a nonlinear ω -ρ term on the EOS is studied. The hyperon couplings are fixed from the optical potential values and the mass-radius curve is determined satisfying the maximum mass constraint of 2 M⊙ for neutron stars, as determined in recent measurements of the pulsar PSR J0348+0432. We also observe that there is no significant advantage of introducing the nonlinear ω -ρ term in the context of obtaining the star mass constraint in the present set of parametrizations.

Quantum geometric phase in Majorana's stellar representation: mapping onto a many-body Aharonov-Bohm phase.

PubMed

Bruno, Patrick

2012-06-15

The (Berry-Aharonov-Anandan) geometric phase acquired during a cyclic quantum evolution of finite-dimensional quantum systems is studied. It is shown that a pure quantum state in a (2J+1)-dimensional Hilbert space (or, equivalently, of a spin-J system) can be mapped onto the partition function of a gas of independent Dirac strings moving on a sphere and subject to the Coulomb repulsion of 2J fixed test charges (the Majorana stars) characterizing the quantum state. The geometric phase may be viewed as the Aharonov-Bohm phase acquired by the Majorana stars as they move through the gas of Dirac strings. Expressions for the geometric connection and curvature, for the metric tensor, as well as for the multipole moments (dipole, quadrupole, etc.), are given in terms of the Majorana stars. Finally, the geometric formulation of the quantum dynamics is presented and its application to systems with exotic ordering such as spin nematics is outlined.

Quantum Geometric Phase in Majorana's Stellar Representation: Mapping onto a Many-Body Aharonov-Bohm Phase

NASA Astrophysics Data System (ADS)

Bruno, Patrick

2012-06-01

The (Berry-Aharonov-Anandan) geometric phase acquired during a cyclic quantum evolution of finite-dimensional quantum systems is studied. It is shown that a pure quantum state in a (2J+1)-dimensional Hilbert space (or, equivalently, of a spin-J system) can be mapped onto the partition function of a gas of independent Dirac strings moving on a sphere and subject to the Coulomb repulsion of 2J fixed test charges (the Majorana stars) characterizing the quantum state. The geometric phase may be viewed as the Aharonov-Bohm phase acquired by the Majorana stars as they move through the gas of Dirac strings. Expressions for the geometric connection and curvature, for the metric tensor, as well as for the multipole moments (dipole, quadrupole, etc.), are given in terms of the Majorana stars. Finally, the geometric formulation of the quantum dynamics is presented and its application to systems with exotic ordering such as spin nematics is outlined.

Network rewiring dynamics with convergence towards a star network

PubMed Central

Dick, G.; Parry, M.

2016-01-01

Network rewiring as a method for producing a range of structures was first introduced in 1998 by Watts & Strogatz (Nature 393, 440–442. (doi:10.1038/30918)). This approach allowed a transition from regular through small-world to a random network. The subsequent interest in scale-free networks motivated a number of methods for developing rewiring approaches that converged to scale-free networks. This paper presents a rewiring algorithm (RtoS) for undirected, non-degenerate, fixed size networks that transitions from regular, through small-world and scale-free to star-like networks. Applications of the approach to models for the spread of infectious disease and fixation time for a simple genetics model are used to demonstrate the efficacy and application of the approach. PMID:27843396

Network rewiring dynamics with convergence towards a star network.

PubMed

Whigham, P A; Dick, G; Parry, M

2016-10-01

Network rewiring as a method for producing a range of structures was first introduced in 1998 by Watts & Strogatz ( Nature 393 , 440-442. (doi:10.1038/30918)). This approach allowed a transition from regular through small-world to a random network. The subsequent interest in scale-free networks motivated a number of methods for developing rewiring approaches that converged to scale-free networks. This paper presents a rewiring algorithm (RtoS) for undirected, non-degenerate, fixed size networks that transitions from regular, through small-world and scale-free to star-like networks. Applications of the approach to models for the spread of infectious disease and fixation time for a simple genetics model are used to demonstrate the efficacy and application of the approach.

Redox-Active Star Molecules Incorporating the 4-Benzolypyridinium Cation: Implications for the Charge Transfer Efficiency Along Branches versus Across the Perimeter in Dendrimers

NASA Technical Reports Server (NTRS)

Yang, Jin-Hua; Rawashdeh, Abdel Monem M.; Oh, Woon Su; Sotiriou-Leventis, Chariklia; Leventis, Nicholas

2003-01-01

We report the redox properties of four star systems incorporating the 4-benzoyl-N-alkylpyridinium cation; the redox potential varies along the branches, but remains constant at fixed radii. Voltammetric analysis (cyclic voltammetry and differential pulse voltammetry) shows that only two of the three redox-active centers in the perimeter are electrochemically accessible during potential sweeps as slow as 20 mV/s and as fast as 10 V/s. On the contrary, both redox centers of a branch are accessible electrochemically within the same time frame. These results are discussed in terms of slow through-space charge transfer and the globular 3-D folding of the molecules.

Observation of Planetary Motion Using a Digital Camera

ERIC Educational Resources Information Center

Meyn, Jan-Peter

2008-01-01

A digital SLR camera with a standard lens (50 mm focal length, f/1.4) on a fixed tripod is used to obtain photographs of the sky which contain stars up to 8[superscript m] apparent magnitude. The angle of view is large enough to ensure visual identification of the photograph with a large sky region in a stellar map. The resolution is sufficient to…

BREAKDOWN OF I-LOVE-Q UNIVERSALITY IN RAPIDLY ROTATING RELATIVISTIC STARS

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

Doneva, Daniela D.; Yazadjiev, Stoytcho S.; Kokkotas, Kostas D.

It was shown recently that normalized relations between the moment of inertia (I), the quadrupole moment (Q), and the tidal deformability (Love number) exist and for slowly rotating neutron stars they are almost independent of the equation of state (EOS). We extend the computation of the I-Q relation to models rotating up to the mass-shedding limit and show that the universality of the relations is lost. With increasing rotation rate, the normalized I-Q relation departs significantly from its slow-rotation limit, deviating up to 40% for neutron stars and up to 75% for strange stars. The deviation is also EOS dependentmore » and for a broad set of hadronic and strange matter EOSs the spread due to rotation is comparable to the spread due to the EOS, if one considers sequences with fixed rotational frequency. Still, for a restricted sample of modern realistic EOSs one can parameterize the deviations from universality as a function of rotation only. The previously proposed I-Love-Q relations should thus be used with care, because they lose their universality in astrophysical situations involving compact objects rotating faster than a few hundred Hz.« less

Hydrostatic equilibrium of stars without electroneutrality constraint

NASA Astrophysics Data System (ADS)

Krivoruchenko, M. I.; Nadyozhin, D. K.; Yudin, A. V.

2018-04-01

The general solution of hydrostatic equilibrium equations for a two-component fluid of ions and electrons without a local electroneutrality constraint is found in the framework of Newtonian gravity theory. In agreement with the Poincaré theorem on analyticity and in the context of Dyson's argument, the general solution is demonstrated to possess a fixed (essential) singularity in the gravitational constant G at G =0 . The regular component of the general solution can be determined by perturbation theory in G starting from a locally neutral solution. The nonperturbative component obtained using the method of Wentzel, Kramers and Brillouin is exponentially small in the inner layers of the star and grows rapidly in the outward direction. Near the surface of the star, both components are comparable in magnitude, and their nonlinear interplay determines the properties of an electro- or ionosphere. The stellar charge varies within the limits of -0.1 to 150 C per solar mass. The properties of electro- and ionospheres are exponentially sensitive to variations of the fluid densities in the central regions of the star. The general solutions of two exactly solvable stellar models without a local electroneutrality constraint are also presented.

Breakdown of I-Love-Q Universality in Rapidly Rotating Relativistic Stars

NASA Astrophysics Data System (ADS)

Doneva, Daniela D.; Yazadjiev, Stoytcho S.; Stergioulas, Nikolaos; Kokkotas, Kostas D.

2014-01-01

It was shown recently that normalized relations between the moment of inertia (I), the quadrupole moment (Q), and the tidal deformability (Love number) exist and for slowly rotating neutron stars they are almost independent of the equation of state (EOS). We extend the computation of the I-Q relation to models rotating up to the mass-shedding limit and show that the universality of the relations is lost. With increasing rotation rate, the normalized I-Q relation departs significantly from its slow-rotation limit, deviating up to 40% for neutron stars and up to 75% for strange stars. The deviation is also EOS dependent and for a broad set of hadronic and strange matter EOSs the spread due to rotation is comparable to the spread due to the EOS, if one considers sequences with fixed rotational frequency. Still, for a restricted sample of modern realistic EOSs one can parameterize the deviations from universality as a function of rotation only. The previously proposed I-Love-Q relations should thus be used with care, because they lose their universality in astrophysical situations involving compact objects rotating faster than a few hundred Hz.

Cortisol release, heart rate and heart rate variability, and superficial body temperature, in horses lunged either with hyperflexion of the neck or with an extended head and neck position.

PubMed

Becker-Birck, M; Schmidt, A; Wulf, M; Aurich, J; von der Wense, A; Möstl, E; Berz, R; Aurich, C

2013-04-01

Bringing the head and neck of ridden horses into a position of hyperflexion is widely used in equestrian sports. In our study, the hypothesis was tested that hyperflexion is an acute stressor for horses. Salivary cortisol concentrations, heart rate, heart rate variability (HRV) and superficial body temperature were determined in horses (n = 16) lunged on two subsequent days. The head and neck of the horse was fixed with side reins in a position allowing forward extension on day A and fixed in hyperflexion on day B. The order of treatments alternated between horses. In response to lunging, cortisol concentration increased (day A from 0.73 ± 0.06 to 1.41 ± 0.13 ng/ml, p < 0.001; day B from 0.68 ± 0.07 to 1.38 ± 0.13 ng/ml, p < 0.001) but did not differ between days A and B. Beat-to-beat (RR) interval decreased in response to lunging on both days. HRV variables standard deviation of RR interval (SDRR) and RMSSD (root mean square of successive RR differences) decreased (p < 0.001) but did not differ between days. In the cranial region of the neck, the difference between maximum and minimum temperature was increased in hyperflexion (p < 0.01). In conclusion, physiological parameters do not indicate an acute stress response to hyperflexion of the head alone in horses lunged at moderate speed and not touched with the whip. However, if hyperflexion is combined with active intervention of a rider, a stressful experience for the horse cannot be excluded. © 2012 Blackwell Verlag GmbH.

The Role of Linear Acceleration in Visual-Vestibular Interactions and Implications in Aircraft Operations

NASA Technical Reports Server (NTRS)

Correia, Manning J.; Luke, Brian L.; McGrath, Braden J.; Clark, John B.; Rupert, Angus H.

1996-01-01

While considerable attention has been given to visual-vestibular interaction (VVI) during angular motion of the head as might occur during an aircraft spin, much less attention has been given to VVI during linear motion of the head. Such interaction might occur, for example, while viewing a stationary or moving display during vertical take-off and landing operations Research into linear VVI, particularly during prolonged periods of linear acceleration, has been hampered by the unavailability of a programmable translator capable of large excursions We collaborated with Otis Elevator Co. and used their research tower and elevator, whose motion could be digitally programmed, to vertically translate human subjects over a distance of 92.3 meters with a peak linear acceleration of 2 meters/sec(exp 2) During pulsatile or sinusoidal translation, the subjects viewed moving stripes (optokinetic stimulus) or a fixed point source (light emitting diode, led, display), respectively and it was generally found that. The direction of linear acceleration relative to the cardinal head axes and the direction of the slow component of optokinetic nystagmus (OKN) determined the extent of VVI during concomitant stripe motion and linear acceleration. Acceleration along the z head axis (A(sub z)) produced the largest VVI, particularly when the slow component of OKN was in the same direction as eye movements produced by the linear acceleration and Eye movements produced by linear acceleration are suppressed by viewing a fixed target at frequencies below 10 Hz But, above this frequency the suppression produced by VVI is removed. Finally, as demonstrated in non-human primates, vergence of the eyes appears to modulate the vertical eye movement response to linear acceleration in humans.

75 FR 51331 - Draft Tier II Environmental Impact Statement: Southeast High Speed Rail Corridor-Richmond, VA...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-19

... Carolina Department of Transportation Rail Division (NCDOT) and the Virginia Department of Rail and Public... Raleigh,'' in the subject heading; or Ms. Christine Fix, Department of Rail & Public Transportation, 600... Department of Rail and Public Transportation Office at 600 East Main Street, Suite 2102, Richmond, VA; and...

A Model of Self-Organizing Head-Centered Visual Responses in Primate Parietal Areas

PubMed Central

Mender, Bedeho M. W.; Stringer, Simon M.

2013-01-01

We present a hypothesis for how head-centered visual representations in primate parietal areas could self-organize through visually-guided learning, and test this hypothesis using a neural network model. The model consists of a competitive output layer of neurons that receives afferent synaptic connections from a population of input neurons with eye position gain modulated retinal receptive fields. The synaptic connections in the model are trained with an associative trace learning rule which has the effect of encouraging output neurons to learn to respond to subsets of input patterns that tend to occur close together in time. This network architecture and synaptic learning rule is hypothesized to promote the development of head-centered output neurons during periods of time when the head remains fixed while the eyes move. This hypothesis is demonstrated to be feasible, and each of the core model components described is tested and found to be individually necessary for successful self-organization. PMID:24349064

Spitzer SAGE-Spec: Near infrared spectroscopy, dust shells, and cool envelopes in extreme Large Magellanic Cloud asymptotic giant branch stars

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

Blum, R. D.; Srinivasan, S.; Kemper, F.

2014-11-01

K-band spectra are presented for a sample of 39 Spitzer Infrared Spectrograph (IRS) SAGE-Spec sources in the Large Magellanic Cloud. The spectra exhibit characteristics in very good agreement with their positions in the near-infrared—Spitzer color-magnitude diagrams and their properties as deduced from the Spitzer IRS spectra. Specifically, the near-infrared spectra show strong atomic and molecular features representative of oxygen-rich and carbon-rich asymptotic giant branch stars, respectively. A small subset of stars was chosen from the luminous and red extreme ''tip'' of the color-magnitude diagram. These objects have properties consistent with dusty envelopes but also cool, carbon-rich ''stellar'' cores. Modest amountsmore » of dust mass loss combine with the stellar spectral energy distribution to make these objects appear extreme in their near-infrared and mid-infrared colors. One object in our sample, HV 915, a known post-asymptotic giant branch star of the RV Tau type, exhibits CO 2.3 μm band head emission consistent with previous work that demonstrates that the object has a circumstellar disk.« less

A Fully Nonlinear, Dynamically Consistent Numerical Model for Solid-Body Ship Motion. I. Ship Motion with Fixed Heading

NASA Technical Reports Server (NTRS)

Lin, Ray-Quing; Kuang, Weijia

2011-01-01

In this paper, we describe the details of our numerical model for simulating ship solidbody motion in a given environment. In this model, the fully nonlinear dynamical equations governing the time-varying solid-body ship motion under the forces arising from ship wave interactions are solved with given initial conditions. The net force and moment (torque) on the ship body are directly calculated via integration of the hydrodynamic pressure over the wetted surface and the buoyancy effect from the underwater volume of the actual ship hull with a hybrid finite-difference/finite-element method. Neither empirical nor free parametrization is introduced in this model, i.e. no a priori experimental data are needed for modelling. This model is benchmarked with many experiments of various ship hulls for heave, roll and pitch motion. In addition to the benchmark cases, numerical experiments are also carried out for strongly nonlinear ship motion with a fixed heading. These new cases demonstrate clearly the importance of nonlinearities in ship motion modelling.

Two-photon imaging of neuronal activity in motor cortex of marmosets during upper-limb movement tasks.

PubMed

Ebina, Teppei; Masamizu, Yoshito; Tanaka, Yasuhiro R; Watakabe, Akiya; Hirakawa, Reiko; Hirayama, Yuka; Hira, Riichiro; Terada, Shin-Ichiro; Koketsu, Daisuke; Hikosaka, Kazuo; Mizukami, Hiroaki; Nambu, Atsushi; Sasaki, Erika; Yamamori, Tetsuo; Matsuzaki, Masanori

2018-05-14

Two-photon imaging in behaving animals has revealed neuronal activities related to behavioral and cognitive function at single-cell resolution. However, marmosets have posed a challenge due to limited success in training on motor tasks. Here we report the development of protocols to train head-fixed common marmosets to perform upper-limb movement tasks and simultaneously perform two-photon imaging. After 2-5 months of training sessions, head-fixed marmosets can control a manipulandum to move a cursor to a target on a screen. We conduct two-photon calcium imaging of layer 2/3 neurons in the motor cortex during this motor task performance, and detect task-relevant activity from multiple neurons at cellular and subcellular resolutions. In a two-target reaching task, some neurons show direction-selective activity over the training days. In a short-term force-field adaptation task, some neurons change their activity when the force field is on. Two-photon calcium imaging in behaving marmosets may become a fundamental technique for determining the spatial organization of the cortical dynamics underlying action and cognition.

Pillars of Creation among Destruction: Star Formation in Molecular Clouds near R136 in 30 Doradus

NASA Astrophysics Data System (ADS)

Kalari, Venu M.; Rubio, Mónica; Elmegreen, Bruce G.; Guzmán, Viviana V.; Zinnecker, Hans; Herrera, Cinthya N.

2018-01-01

We present new sensitive CO(2–1) observations of the 30 Doradus region in the Large Magellanic Cloud. We identify a chain of three newly discovered molecular clouds that we name KN1, KN2, and KN3 lying within 2–14 pc in projection from the young massive cluster R136 in 30 Doradus. Excited H2 2.12 μm emission is spatially coincident with the molecular clouds, but ionized Brγ emission is not. We interpret these observations as the tails of pillar-like structures whose ionized heads are pointing toward R136. Based on infrared photometry, we identify a new generation of stars forming within this structure.

40 CFR 180.635 - Spinetoram; tolerances for residues.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Banana 0.25 Beet, sugar, molasses 0.75 Biriba 0.30 Brassica, head and stem, subgroup 5A 2.0 Brassica... Cherimoya 0.30 Citrus, dried pulp 0.50 Citrus, oil 3.0 Corn, sweet, kernel plus cob with husks removed 0.04... 0.30 Star fruit 0.30 Strawberry 1.0 Sugar apple 0.30 Ti, leaves 10 Vegetable, bulb, group 3, except...

40 CFR 180.495 - Spinosad; tolerances for residues.

Code of Federal Regulations, 2012 CFR

2012-07-01

....2 Atemoya 0.3 Avocado 0.3 Banana 0.25 Beet, sugar, molasses 0.75 Biriba 0.3 Brassica, head and stem... liver 5.0 Cherimoya 0.3 Citrus, oil 3.0 Citrus, dried pulp 0.5 Coriander, leaves 8.0 Corn, sweet, kernel... Star apple 0.3 Starfruit 0.3 Strawberry 1.0 Sugar apple 0.3 Ti, leaves 10.0 Vegetable, bulb, group 3...

40 CFR 180.495 - Spinosad; tolerances for residues.

Code of Federal Regulations, 2013 CFR

2013-07-01

....2 Atemoya 0.3 Avocado 0.3 Banana 0.25 Beet, sugar, molasses 0.75 Biriba 0.3 Brassica, head and stem... liver 5.0 Cherimoya 0.3 Citrus, oil 3.0 Citrus, dried pulp 0.5 Coriander, leaves 8.0 Corn, sweet, kernel... Star apple 0.3 Starfruit 0.3 Strawberry 1.0 Sugar apple 0.3 Ti, leaves 10.0 Vegetable, bulb, group 3...

40 CFR 180.635 - Spinetoram; tolerances for residues.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Banana 0.25 Beet, sugar, molasses 0.75 Biriba 0.30 Brassica, head and stem, subgroup 5A 2.0 Brassica... Cherimoya 0.30 Citrus, dried pulp 0.50 Citrus, oil 3.0 Corn, sweet, kernel plus cob with husks removed 0.04... 0.30 Star fruit 0.30 Strawberry 1.0 Sugar apple 0.30 Ti, leaves 10 Vegetable, bulb, group 3, except...

40 CFR 180.495 - Spinosad; tolerances for residues.

Code of Federal Regulations, 2014 CFR

2014-07-01

....2 Atemoya 0.3 Avocado 0.3 Banana 0.25 Beet, sugar, molasses 0.75 Biriba 0.3 Brassica, head and stem... liver 5.0 Cherimoya 0.3 Citrus, oil 3.0 Citrus, dried pulp 0.5 Coriander, leaves 8.0 Corn, sweet, kernel... Star apple 0.3 Starfruit 0.3 Strawberry 1.0 Sugar apple 0.3 Ti, leaves 10.0 Vegetable, bulb, group 3...

40 CFR 180.635 - Spinetoram; tolerances for residues.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Banana 0.25 Beet, sugar, molasses 0.75 Biriba 0.30 Brassica, head and stem, subgroup 5A 2.0 Brassica... Cherimoya 0.30 Citrus, dried pulp 0.50 Citrus, oil 3.0 Corn, sweet, kernel plus cob with husks removed 0.04... 0.30 Star fruit 0.30 Strawberry 1.0 Sugar apple 0.30 Ti, leaves 10 Vegetable, bulb, group 3, except...

New head exposure system for use in human provocation studies with EEG recording during GSM900- and UMTS-like exposure.

PubMed

Schmid, Gernot; Cecil, Stefan; Goger, Christoph; Trimmel, Michael; Kuster, Niels; Molla-Djafari, Hamid

2007-12-01

A new head exposure system for double blinded human provocation studies, which requires EEG recording during exposure with GSM900- and UMTS-like signals has been developed and dosimetrically evaluated. The system uses planar patch antennas fixed at 65 mm distance from the subject's head by a special headset, which provides minimum impairment of the test subjects and ensures an almost constant position of the antennas with respect to the head, even in case of head movements. Compared to exposure concepts operating small antennas in close proximity to the head, the concept of planar antennas at a certain distance from the head produces a much more homogeneous SAR distribution in the temporal and parietal lobe of the brain. At the same time the resulting uncertainty of exposure due to variations in head size, variations of the dielectric properties of tissues and unavoidable small changes of the antenna's position with respect to the head, is reduced to the order of approximately 3 dB, which is a significant improvement to comparable head exposure systems reported in literature in the past. To avoid electromagnetic interference on the EEG recording caused by the incident RF-field an appropriate double-shielded filter circuit has been developed. Furthermore, the effect of the presence of the sintered Ag/AgCl EEG electrodes and electrode wires on the SAR distribution inside the head has been investigated and was found to be minimal if the electrode wires are arranged orthogonal to the incident electric field vector. EEG electrode arrangement parallel to the incident field vector, however, might cause drastic changes in the SAR distribution inside the head. (c) 2007 Wiley-Liss, Inc.

Effects of volute geometry and impeller orbit on the hydraulic performance of a centrifugal pump

NASA Technical Reports Server (NTRS)

Flack, R. D.; Lanes, R. F.

1983-01-01

Overall performance data was taken for a Plexiglas water pump with a logarithmic spiral volute and rectangular cross sectioned flow channels. Parametric studies were made in which the center of the impeller was offset from the design center of the volute. The rig was also designed such that the impeller was allowed to synchronously orbit by a fixed amount about any center. The studies indicate that decreasing the tongue clearance decreases the head at low flowrates and increases the head at high flowrates. Also, decreasing the volute area in the first half of the volute and holding the tongue clearance the same, resulted in a decreased head for low flowrates but performance at high flowrates was not affected. Finally, the overall hydraulic performance was not affected by the impeller orbitting about the volute center.

Two-component gravitational instability in spiral galaxies

NASA Astrophysics Data System (ADS)

Marchuk, A. A.; Sotnikova, N. Y.

2018-04-01

We applied a criterion of gravitational instability, valid for two-component and infinitesimally thin discs, to observational data along the major axis for seven spiral galaxies of early types. Unlike most papers, the dispersion equation corresponding to the criterion was solved directly without using any approximation. The velocity dispersion of stars in the radial direction σR was limited by the range of possible values instead of a fixed value. For all galaxies, the outer regions of the disc were analysed up to R ≤ 130 arcsec. The maximal and sub-maximal disc models were used to translate surface brightness into surface density. The largest destabilizing disturbance stars can exert on a gaseous disc was estimated. It was shown that the two-component criterion differs a little from the one-fluid criterion for galaxies with a large surface gas density, but it allows to explain large-scale star formation in those regions where the gaseous disc is stable. In the galaxy NGC 1167 star formation is entirely driven by the self-gravity of the stars. A comparison is made with the conventional approximations which also include the thickness effect and with models for different sound speed cg. It is shown that values of the effective Toomre parameter correspond to the instability criterion of a two-component disc Qeff < 1.5-2.5. This result is consistent with previous theoretical and observational studies.

Testing Intermittence of the Galactic Star Formation History along with the Infall Model

NASA Astrophysics Data System (ADS)

Takeuchi, Tsutomu T.; Hirashita, Hiroyuki

2000-09-01

We analyze the star formation history (SFH) of the Galactic disk by using an infall model. Based on the observed SFH of the Galactic disk, we first determine the timescale of the gas infall into the Galactic disk (tin) and that of the gas consumption to form stars (tsf). Since each of the two timescales does not prove to be determined independently from the SFH, we first fix tsf. Then, tin is determined so that we minimize χ2. Consequently, we choose three parameter sets: [tsf (Gyr),tin (Gyr)]=(6.0, 23), (11, 12), and (15, 9.0), where we set the Galactic age as 15 Gyr. All of the three cases predict almost identical star formation history. Next, we test the intermittence (or variability) of the star formation rate (SFR) along with the smooth SFH suggested from the infall model. The large value of the χ2 statistic supports the violent time variation of the SFH. If we interpret the observed SFH with smooth and variable components, the amplitude of the variable component is comparable to the smooth component. Thus, intermittent SFH of the Galactic disk is strongly suggested. We also examined the metallicity distribution of G dwarfs. We found that the true parameter set lies between [tsf (Gyr),tin (Gyr)]=(6, 23) and (11, 12), though we need a more sophisticated model including the process of metal enrichment within the Galactic halo.

The colour-magnitude relation of globular clusters in Centaurus and Hydra. Constraints on star cluster self-enrichment with a link to massive Milky Way globular clusters

NASA Astrophysics Data System (ADS)

Fensch, J.; Mieske, S.; Müller-Seidlitz, J.; Hilker, M.

2014-07-01

Aims: We investigate the colour-magnitude relation of metal-poor globular clusters, the so-called blue tilt, in the Hydra and Centaurus galaxy clusters and constrain the primordial conditions for star cluster self-enrichment. Methods: We analyse U,I photometry for about 2500 globular clusters in the central regions of Hydra and Centaurus, based on VLT/FORS1 data. We measure the relation between mean colour and luminosity for the blue and red subpopulation of the globular cluster samples. We convert these relations into mass-metallicity space and compare the obtained GC mass-metallicity relation with predictions from the star cluster self-enrichment model by Bailin & Harris (2009, ApJ, 695, 1082). For this we include effects of dynamical and stellar evolution and a physically well motivated primordial mass-radius scaling. Results: We obtain a mass-metallicity scaling of Z ∝ M0.27 ± 0.05 for Centaurus GCs and Z ∝ M0.40 ± 0.06 for Hydra GCs, consistent with the range of observed relations in other environments. We find that the GC mass-metallicity relation already sets in at present-day masses of a few and is well established in the luminosity range of massive MW clusters like ω Centauri. The inclusion of a primordial mass-radius scaling of star clusters significantly improves the fit of the self-enrichment model to the data. The self-enrichment model accurately reproduces the observed relations for average primordial half-light radii rh ~ 1-1.5 pc, star formation efficiencies f⋆ ~ 0.3-0.4, and pre-enrichment levels of [Fe/H] - 1.7 dex. The slightly steeper blue tilt for Hydra can be explained either by a ~30% smaller average rh at fixed f⋆ ~ 0.3, or analogously by a ~20% smaller f⋆ at fixed rh ~ 1.5 pc. Within the self-enrichment scenario, the observed blue tilt implies a correlation between GC mass and width of the stellar metallicity distribution. We find that this implied correlation matches the trend of width with GC mass measured in Galactic GCs, including extreme cases like ω Centauri and M 54. Conclusions: First, we found that a primordial star cluster mass-radius relation provides a significant improvement to the self-enrichment model fits. Second we show that broadened metallicity distributions as found in some massive MW globular clusters may have arisen naturally from self-enrichment processes, without the need of a dwarf galaxy progenitor.

Nebular Emission Line Ratios in z ≃ 2-3 Star-forming Galaxies with KBSS-MOSFIRE: Exploring the Impact of Ionization, Excitation, and Nitrogen-to-Oxygen Ratio

NASA Astrophysics Data System (ADS)

Strom, Allison L.; Steidel, Charles C.; Rudie, Gwen C.; Trainor, Ryan F.; Pettini, Max; Reddy, Naveen A.

2017-02-01

We present a detailed study of the rest-optical (3600-7000 Å) nebular spectra of ˜380 star-forming galaxies at z≃ 2{--}3, obtained with Keck/Multi-object Spectrometer for Infrared Exploration (MOSFIRE) as part of the Keck Baryonic Structure Survey (KBSS). The KBSS-MOSFIRE sample is representative of star-forming galaxies at these redshifts, with stellar masses {M}* ={10}9{--}{10}11.5 {M}⊙ and star formation rates SFR = 3-1000 {M}⊙ yr-1. We focus on robust measurements of many strong diagnostic emission lines for individual galaxies: [O II]λλ3727, 3729, [Ne III]λ3869, Hβ, [O III]λ λ 4960, 5008, [N II]λλ 6549, 6585, Hα, and [S II]λλ6718, 6732. Comparisons with observations of typical local galaxies from the Sloan Digital Sky Survey and between subsamples of KBSS-MOSFIRE show that high-redshift galaxies exhibit a number of significant differences in addition to the well-known offset in log([O III]λ 5008/Hβ) and log([N II]λ 6585/Hα). We argue that the primary difference between H II regions in z˜ 2.3 galaxies and those at z˜ 0 is an enhancement in the degree of nebular excitation, as measured by [O III]/Hβ and {{R}}23\\equiv {log}[([O III]λ λ 4960,5008+[O II]λ λ 3727,3729)/Hβ]. At the same time, KBSS-MOSFIRE galaxies are ˜10 times more massive than z˜ 0 galaxies with similar ionizing spectra and have higher N/O (likely accompanied by higher O/H) at fixed excitation. These results indicate the presence of harder ionizing radiation fields at fixed N/O and O/H relative to typical z˜ 0 galaxies, consistent with Fe-poor stellar population models that include massive binaries, and highlight a population of massive, high-specific star formation rate galaxies at high redshift with systematically different star formation histories than galaxies of similar stellar mass today. The data presented in this paper were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The observatory was made possible by the generous financial support of the W.M. Keck Foundation.

Horsehead nebula

NASA Technical Reports Server (NTRS)

1999-01-01

Rising from a sea of dust and gas like a giant seahorse, the Horsehead nebula is one of the most photographed objects in the sky. NASA's Hubble Space Telescope took a close-up look at this heavenly icon, revealing the cloud's intricate structure. This detailed view of the horse's head is being released to celebrate the orbiting observatory's eleventh anniversary. Produced by the Hubble Heritage Project, this picture is a testament to the Horsehead's popularity. Internet voters selected this object for the orbiting telescope to view.

The Horsehead, also known as Barnard 33, is a cold, dark cloud of gas and dust, silhouetted against the bright nebula, IC 434. The bright area at the top left edge is a young star still embedded in its nursery of gas and dust. But radiation from this hot star is eroding the stellar nursery. The top of the nebula also is being sculpted by radiation from a massive star located out of Hubble's field of view.

Only by chance does the nebula roughly resemble the head of a horse. Its unusual shape was first discovered on a photographic plate in the late 1800s. Located in the constellation Orion, the Horsehead is a cousin of the famous pillars of dust and gas known as the Eagle nebula. Both tower-like nebulas are cocoons of young stars.

The Horsehead nebula lies just south of the bright star Zeta Orionis, which is easily visible to the unaided eye as the left-hand star in the line of three that form Orion's Belt. Amateur astronomers often use the Horsehead as a test of their observing skills; it is known as one of the more difficult objects to see visually in an amateur-sized telescope.

The magnificent extent of the Horsehead is best appreciated in a new wide-field image of the nebula being released today by the National Optical Astronomy Observatory, taken by Travis Rector with the National Science Foundation's 0.9 meter telescope at Kitt Peak National Observatory near Tucson, AZ.

This popular celestial target was the clear winner among more than 5,000 Internet voters, who were asked last year to select an astronomical target for the Hubble telescope to observe. The voters included students, teachers, and professional and amateur astronomers.

This 11th anniversary release image was composed by the Hubble Heritage Team, which superimposed Hubble data onto ground-based data (limited to small triangular regions around the outer edge of the image). Ground-based image courtesy of Nigel A. Sharp (NOAO/AURA/NSF) taken at the 0.9-meter telescope on Kitt Peak.

WELDING METHOD

DOEpatents

Cornell, A.A.; Dunbar, J.V.; Ruffner, J.H.

1959-09-29

A semi-automatic method is described for the weld joining of pipes and fittings which utilizes the inert gasshielded consumable electrode electric arc welding technique, comprising laying down the root pass at a first peripheral velocity and thereafter laying down the filler passes over the root pass necessary to complete the weld by revolving the pipes and fittings at a second peripheral velocity different from the first peripheral velocity, maintaining the welding head in a fixed position as to the specific direction of revolution, while the longitudinal axis of the welding head is disposed angularly in the direction of revolution at amounts between twenty minutas and about four degrees from the first position.

CONSTRAINTS OF THE PHYSICS OF LOW-MASS AGB STARS FROM CH AND CEMP STARS

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

Cristallo, S.; Piersanti, L.; Gobrecht, D.

2016-12-20

We analyze a set of published elemental abundances from a sample of CH stars which are based on high resolution spectral analysis of ELODIE and SUBARU/HDS spectra. All the elemental abundances were derived from local thermodynamic equilibrium analysis using model atmospheres, and thus they represent the largest homogeneous abundance data available for CH stars to date. For this reason, we can use the set to constrain the physics and the nucleosynthesis occurring in low mass asymptotic giant branch (AGB) s.tars. CH stars have been polluted in the past from an already extinct AGB companion and thus show s-process enriched surfaces.more » We discuss the effects induced on the surface AGB s-process distributions by different prescriptions for convection and rotation. Our reference theoretical FRUITY set fits only part of the observations. Moreover, the s-process observational spread for a fixed metallicity cannot be reproduced. At [Fe/H] > −1, a good fit is found when rotation and a different treatment of the inner border of the convective envelope are simultaneously taken into account. In order to increase the statistics at low metallicities, we include in our analysis a selected number of CEMP stars and, therefore, we compute additional AGB models down to [Fe/H] = −2.85. Our theoretical models are unable to attain the large [hs/ls] ratios characterizing the surfaces of those objects. We speculate on the reasons for such a discrepancy, discussing the possibility that the observed distribution is a result of a proton mixing episode leading to a very high neutron density (the so-called i-process).« less

Kepler Mission: a Discovery-Class Mission Designed to Determine the Frequency of Earth-Size and Larger Planets Around Solar-Like Stars

NASA Technical Reports Server (NTRS)

Borucki, William; Koch, David; Lissauer, Jack; Basri, Gibor; Caldwell, John; Cochran, William; Dunham, Edward W.; Gilliland, Ronald; Caldwell, Douglas; Kondo, Yoji;

Integration of visual and non-visual self-motion cues during voluntary head movements in the human brain.

PubMed

Schindler, Andreas; Bartels, Andreas

2018-05-15

Our phenomenological experience of the stable world is maintained by continuous integration of visual self-motion with extra-retinal signals. However, due to conventional constraints of fMRI acquisition in humans, neural responses to visuo-vestibular integration have only been studied using artificial stimuli, in the absence of voluntary head-motion. We here circumvented these limitations and let participants to move their heads during scanning. The slow dynamics of the BOLD signal allowed us to acquire neural signal related to head motion after the observer's head was stabilized by inflatable aircushions. Visual stimuli were presented on head-fixed display goggles and updated in real time as a function of head-motion that was tracked using an external camera. Two conditions simulated forward translation of the participant. During physical head rotation, the congruent condition simulated a stable world, whereas the incongruent condition added arbitrary lateral motion. Importantly, both conditions were precisely matched in visual properties and head-rotation. By comparing congruent with incongruent conditions we found evidence consistent with the multi-modal integration of visual cues with head motion into a coherent "stable world" percept in the parietal operculum and in an anterior part of parieto-insular cortex (aPIC). In the visual motion network, human regions MST, a dorsal part of VIP, the cingulate sulcus visual area (CSv) and a region in precuneus (Pc) showed differential responses to the same contrast. The results demonstrate for the first time neural multimodal interactions between precisely matched congruent versus incongruent visual and non-visual cues during physical head-movement in the human brain. The methodological approach opens the path to a new class of fMRI studies with unprecedented temporal and spatial control over visuo-vestibular stimulation. Copyright © 2018 Elsevier Inc. All rights reserved.

How Bell Labs creates star performers.

PubMed

Kelley, R; Caplan, J

1993-01-01

How can managers increase the productivity of professionals when most of their work goes on inside their heads? Robert Kelley and Janet Caplan believe that defining the difference between star performers and average workers is the answer. Many managers assume that top performers are just smarter. But the authors' research at the Bell Laboratories Switching Systems Business Unit (SSBU) has revealed that the real difference between stars and average workers is not IQ but the ways top performers do their jobs. Their study has led to a training program based on the strategies of star performers. The SSBU training program, known as the Productivity Enhancement Group (PEG), uses an expert model to demystify productivity. The star engineers selected to develop the expert model identified and ranked nine work strategies, such as taking initiative, networking, and self-management. Middle performers were also asked what makes for top-quality work, but their definitions and ranking of the strategies differed significantly from those of the top performers. Taking initiative, for example, meant something very different to an average worker than it did to a star. And for the middle performers, the ability to give good presentations was a core strategy, while it was peripheral for the top engineers. Once PEG got underway, respected engineers ran the training sessions, which included case studies, work-related exercises, and frank discussion. The benefits of the program were striking: participants and managers reported substantial productivity increases in both star and average performers. The PEG program may not be a blueprint for other companies, but its message is clear: managers must focus on people, not on technology, to increase productivity in the knowledge economy.

jsc2013e080223

NASA Image and Video Library

2013-09-06

At the Gagarin Cosmonaut Training Center in Star City, Russia, Expedition 37/38 Soyuz Commander Oleg Kotov (second from left) holds a toy cat mascot during a pre-launch news conference Sept. 6 as his crewmates, Flight Engineer Michael Hopkins of NASA (far left) and Flight Engineer Sergey Ryazanskiy (second from the right) look on. Also participating in the news conference was the head of the Cosmonaut Training Center, Sergei Krikalev (far right). The mascot will be mounted inside the crew’s Soyuz TMA-10M spacecraft over Kotov’s head as a “zero-g indicator” once the crew launches. Their launch to the International Space Station is set for Sept. 26, Kazakh time, from the Baikonur Cosmodrome in Kazakhstan. NASA/Stephanie Stoll

Head-Worn Display Concepts for Surface Operations for Commerical Aircraft

NASA Technical Reports Server (NTRS)

Arthur, Jarvis J., III; Prinzel, Lawrence J., III; Bailey, Randall E.; Shelton, Kevin J.; Williams, Steven P.; Kramer, Lynda J.; Norman, Robert M.

2008-01-01

Experiments and flight tests have shown that a Head-Up Display (HUD) and a head-down electronic moving map (EMM) can be enhanced with Synthetic Vision for airport surface operations. While great success in ground operations was demonstrated with a HUD, the research noted that two major HUD limitations during ground operations were its monochrome form and limited, fixed field-of-regard. A potential solution to these limitations found with HUDs may be emerging with Head Worn Displays (HWDs). HWDs are small display devices that may be worn without significant encumbrance to the user. By coupling the HWD with a head tracker, unlimited field-of-regard may be realized. The results of three ground simulation experiments conducted at NASA Langley Research Center are summarized. The experiments evaluated the efficacy of head-worn display applications of Synthetic Vision and Enhanced Vision technology to improve transport aircraft surface operations. The results of the experiments showed that the fully integrated HWD provided greater pilot performance with respect to staying on the path compared to using paper charts alone. Further, when comparing the HWD with the HUD concept, there were no differences in path performance. In addition, the HWD and HUD concepts were rated via paired-comparisons the same in terms of situation awareness and workload.

Addition of lysophospholipids with large head groups to cells inhibits Shiga toxin binding.

PubMed

Ailte, Ieva; Lingelem, Anne Berit Dyve; Kavaliauskiene, Simona; Bergan, Jonas; Kvalvaag, Audun Sverre; Myrann, Anne-Grethe; Skotland, Tore; Sandvig, Kirsten

2016-07-26

Shiga toxin (Stx), an AB5 toxin, binds specifically to the neutral glycosphingolipid Gb3 at the cell surface before being transported into cells. We here demonstrate that addition of conical lysophospholipids (LPLs) with large head groups inhibit Stx binding to cells whereas LPLs with small head groups do not. Lysophosphatidylinositol (LPI 18:0), the most efficient LPL with the largest head group, was selected for in-depth investigations to study how the binding of Stx is regulated. We show that the inhibition of Stx binding by LPI is reversible and possibly regulated by cholesterol since addition of methyl-β-cyclodextrin (mβCD) reversed the ability of LPI to inhibit binding. LPI-induced inhibition of Stx binding is independent of signalling and membrane turnover as it occurs in fixed cells as well as after depletion of cellular ATP. Furthermore, data obtained with fluorescent membrane dyes suggest that LPI treatment has a direct effect on plasma membrane lipid packing with shift towards a liquid disordered phase in the outer leaflet, while lysophosphoethanolamine (LPE), which has a small head group, does not. In conclusion, our data show that cellular treatment with conical LPLs with large head groups changes intrinsic properties of the plasma membrane and modulates Stx binding to Gb3.

Limited Evaluation of Image Quality Produced by a Portable Head CT Scanner (CereTom) in a Neurosurgery Centre.

PubMed

Abdullah, Ariz Chong; Adnan, Johari Siregar; Rahman, Noor Azman A; Palur, Ravikant

2017-03-01

Computed tomography (CT) is the preferred diagnostic toolkit for head and brain imaging of head injury. A recent development is the invention of a portable CT scanner that can be beneficial from a clinical point of view. To compare the quality of CT brain images produced by a fixed CT scanner and a portable CT scanner (CereTom). This work was a single-centre retrospective study of CT brain images from 112 neurosurgical patients. Hounsfield units (HUs) of the images from CereTom were measured for air, water and bone. Three assessors independently evaluated the images from the fixed CT scanner and CereTom. Streak artefacts, visualisation of lesions and grey-white matter differentiation were evaluated at three different levels (centrum semiovale, basal ganglia and middle cerebellar peduncles). Each evaluation was scored 1 (poor), 2 (average) or 3 (good) and summed up to form an ordinal reading of 3 to 9. HUs for air, water and bone from CereTom were within the recommended value by the American College of Radiology (ACR). Streak artefact evaluation scores for the fixed CT scanner was 8.54 versus 7.46 ( Z = -5.67) for CereTom at the centrum semiovale, 8.38 (SD = 1.12) versus 7.32 (SD = 1.63) at the basal ganglia and 8.21 (SD = 1.30) versus 6.97 (SD = 2.77) at the middle cerebellar peduncles. Grey-white matter differentiation showed scores of 8.27 (SD = 1.04) versus 7.21 (SD = 1.41) at the centrum semiovale, 8.26 (SD = 1.07) versus 7.00 (SD = 1.47) at the basal ganglia and 8.38 (SD = 1.11) versus 6.74 (SD = 1.55) at the middle cerebellar peduncles. Visualisation of lesions showed scores of 8.86 versus 8.21 ( Z = -4.24) at the centrum semiovale, 8.93 versus 8.18 ( Z = -5.32) at the basal ganglia and 8.79 versus 8.06 ( Z = -4.93) at the middle cerebellar peduncles. All results were significant with P -value < 0.01. Results of the study showed a significant difference in image quality produced by the fixed CT scanner and CereTom, with the latter being more inferior than the former. However, HUs of the images produced by CereTom do fulfil the recommendation of the ACR.

On the optically thick winds of Wolf-Rayet stars

NASA Astrophysics Data System (ADS)

Gräfener, G.; Owocki, S. P.; Grassitelli, L.; Langer, N.

2017-12-01

Context. The classical Wolf-Rayet (WR) phase is believed to mark the end stage of the evolution of massive stars with initial masses higher than 25M⊙. Stars in this phase expose their stripped cores with the products of H- or He-burning at their surface. They develop strong, optically thick stellar winds that are important for the mechanical and chemical feedback of massive stars, and that determine whether the most massive stars end their lives as neutron stars or black holes. The winds of WR stars are currently not well understood, and their inclusion in stellar evolution models relies on uncertain empirical mass-loss relations. Aims: We investigate theoretically the mass-loss properties of H-free WR stars of the nitrogen sequence (WN stars). Methods: We connected stellar structure models for He stars with wind models for optically thick winds and assessed the degree to which these two types of models can simultaneously fulfil their respective sonic-point conditions. Results: Fixing the outer wind law and terminal wind velocity ν∞, we obtain unique solutions for the mass-loss rates of optically thick, radiation-driven winds of WR stars in the phase of core He-burning. The resulting mass-loss relations as a function of stellar parameters agree well with previous empirical relations. Furthermore, we encounter stellar mass limits below which no continuous solutions exist. While these mass limits agree with observations of WR stars in the Galaxy, they contradict observations in the LMC. Conclusions: While our results in particular confirm the slope of often-used empirical mass-loss relations, they imply that only part of the observed WN population can be understood in the framework of the standard assumptions of a smooth transonic flow and compact stellar core. This means that alternative approaches such as a clumped and inflated wind structure or deviations from the diffusion limit at the sonic point may have to be invoked. Qualitatively, the existence of mass limits for the formation of WR-type winds may be relevant for the non-detection of low-mass WR stars in binary systems, which are believed to be progenitors of Type Ib/c supernovae. The sonic-point conditions derived in this work may provide a possibility to include optically thick winds in stellar evolution models in a more physically motivated form than in current models.

Unified Medical Command and Control in the Department of Defense

DTIC Science & Technology

2012-03-22

This is the Joint Task Force – Capital Medical (JTF CAPMED ) model, in which organizations, resources, and personnel are aligned under a single...This was demonstrated in the formation of the JTF- CAPMED , designed as a 3-star level command controlling military medical activities in the National...used ground vehicles, helicopters and fixed wing aircraft for strategic casualty evacuation (CASEVAC). Enroute care is standard and critical in

A tale of two anomalies: Depletion, dispersion, and the connection between the stellar lithium spread and inflated radii on the pre-main sequence

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

Somers, Garrett; Pinsonneault, Marc H., E-mail: somers@astronomy.ohio-state.edu, E-mail: pinsono@astronomy.ohio-state.edu

2014-07-20

We investigate lithium depletion in standard stellar models (SSMs) and main sequence (MS) open clusters, and explore the origin of the Li dispersion in young, cool stars of equal mass, age, and composition. We first demonstrate that SSMs accurately predict the Li abundances of solar analogs at the zero-age main sequence (ZAMS) within theoretical uncertainties. We then measure the rate of MS Li depletion by removing the [Fe/H]-dependent ZAMS Li pattern from three well-studied clusters, and comparing the detrended data. MS depletion is found to be mass-dependent, in the sense of more depletion at low mass. A dispersion in Limore » abundance at fixed T{sub eff} is nearly universal, and sets in by ∼200 Myr. We discuss mass and age dispersion trends, and the pattern is mixed. We argue that metallicity impacts the ZAMS Li pattern, in agreement with theoretical expectations but contrary to the findings of some previous studies, and suggest Li as a test of cluster metallicity. Finally, we argue that a radius dispersion in stars of fixed mass and age, during the epoch of pre-MS Li destruction, is responsible for the spread in Li abundances and the correlation between rotation and Li in young cool stars, most well known in the Pleiades. We calculate stellar models, inflated to match observed radius anomalies in magnetically active systems, and the resulting range of Li abundances reproduces the observed patterns of young clusters. We discuss ramifications for pre-MS evolutionary tracks and age measurements of young clusters, and suggest an observational test.« less

Effects of Olympic-style taekwondo kicks on an instrumented head-form and resultant injury measures.

PubMed

Fife, Gabriel P; O'Sullivan, David M; Pieter, Willy; Cook, David P; Kaminski, Thomas W

2013-12-01

The objective of this study was to assess the effect of taekwondo kicks and peak foot velocity (FVEL) on resultant head linear acceleration (RLA), head injury criterion (HIC15) and head velocity (HVEL). Each subject (n=12) randomly performed five repetitions of the turning kick (TK), clench axe kick (CA), front leg axe kick, jump back kick (JB) and jump spinning hook kick (JH) at the average standing head height for competitors in their weight division. A Hybrid II Crash Test Dummy head was fitted with a protective taekwondo helmet and instrumented with a triaxial accelerometer and fixed to a height-adjustable frame. Resultant head linear acceleration, HVEL, FVEL data were captured and processed using Qualysis Track Manager. The TK (130.11 ± 51.67 g) produced a higher RLA than the CA (54.95 ± 20.08 g, p<0.001, d=1.84) and a higher HIC15 than the JH (672.74 ± 540.89 vs 300.19 ± 144.35, p<0.001, ES=0.97). There was no difference in HVEL of the TK (4.73 ± 1.67 m/s) and that of the JB (4.43 ± 0.78 m/s; p=0.977, ES<0.01). The TK is of concern because it is the most common technique and cause of concussion in taekwondo. Future studies should aim to understand rotational accelerations of the head.

A List of U.S. Government Medical and Dental 8mm Films for Sale by the National Audiovisual Center.

ERIC Educational Resources Information Center

National Archives and Records Service (GSA), Washington, DC. National Audiovisual Center.

Over 200 8mm films for the use of doctors, dentists, and others in related fields are listed. Dental films are categorized into the following topics: anatomy -- head and neck; complete dentures; diagnosis; endodontics; fixed partial dentures; occlusion; operative dentistry; oral hygiene; patient education; periodontics; radiology; removable…

Performance Analysis of Cluster Formation in Wireless Sensor Networks.

PubMed

Montiel, Edgar Romo; Rivero-Angeles, Mario E; Rubino, Gerardo; Molina-Lozano, Heron; Menchaca-Mendez, Rolando; Menchaca-Mendez, Ricardo

2017-12-13

Clustered-based wireless sensor networks have been extensively used in the literature in order to achieve considerable energy consumption reductions. However, two aspects of such systems have been largely overlooked. Namely, the transmission probability used during the cluster formation phase and the way in which cluster heads are selected. Both of these issues have an important impact on the performance of the system. For the former, it is common to consider that sensor nodes in a clustered-based Wireless Sensor Network (WSN) use a fixed transmission probability to send control data in order to build the clusters. However, due to the highly variable conditions experienced by these networks, a fixed transmission probability may lead to extra energy consumption. In view of this, three different transmission probability strategies are studied: optimal, fixed and adaptive. In this context, we also investigate cluster head selection schemes, specifically, we consider two intelligent schemes based on the fuzzy C-means and k-medoids algorithms and a random selection with no intelligence. We show that the use of intelligent schemes greatly improves the performance of the system, but their use entails higher complexity and selection delay. The main performance metrics considered in this work are energy consumption, successful transmission probability and cluster formation latency. As an additional feature of this work, we study the effect of errors in the wireless channel and the impact on the performance of the system under the different transmission probability schemes.

Histological Observation of the Retinacula of Weitbrecht and Its Clinical Significance: A cadaveric study.

PubMed

Dou, Bang; Mei, Jiong; Wang, Zhiyuan; Ni, Ming; Jia, Guangyao; Liu, Shiwei

2018-01-01

The retinacular arteries provide major supply to the femoral head, their injuries may lead to the femoral head necrosis (FHN) in femoral neck fractures. Although the femoral neck fracture was seriously displaced in some patients, FHN did not occur, which suggests that the blood supply is not fully blocked. This study was aimed to find the association between the structure of the retinacula of Weitbrecht and the mechanism of protecting retinacular arteries from being injured. Fourteen formalin-fixed cadaveric specimens (in 28 hips) with no significant vascular disease were observed. The retinacula were cut longitudinally and then cut into three parts: medial, middle, and lateral. These specimens were stained using hematoxylin and eosin and improved Masson Trichrome stain. The microstructure and tightness of the retinacula fixed to the bone and the distribution of vessels were examined under a stereoscope, an optical microscope, and a scanning electron microscope. The microstructure and compactness in each part of retinacula were different, and the tightness of the fibers of the retinacula fixed to the bone in each part were different. A particular structure which resembled a Sandwich panels was observed, and it may be an effective mechanism of protecting retinacular arteries. The Sandwich panels structure existed generally in the retinacula of Weitbrecht, and this sandwich panelture may play very important role in protecting the retinaculum artery from being injured, which show the importance of protecting the retinacular artery in the treatment of femoral neck fractures.

Performance Analysis of Cluster Formation in Wireless Sensor Networks

PubMed Central

Montiel, Edgar Romo; Rivero-Angeles, Mario E.; Rubino, Gerardo; Molina-Lozano, Heron; Menchaca-Mendez, Rolando; Menchaca-Mendez, Ricardo

2017-01-01

Clustered-based wireless sensor networks have been extensively used in the literature in order to achieve considerable energy consumption reductions. However, two aspects of such systems have been largely overlooked. Namely, the transmission probability used during the cluster formation phase and the way in which cluster heads are selected. Both of these issues have an important impact on the performance of the system. For the former, it is common to consider that sensor nodes in a clustered-based Wireless Sensor Network (WSN) use a fixed transmission probability to send control data in order to build the clusters. However, due to the highly variable conditions experienced by these networks, a fixed transmission probability may lead to extra energy consumption. In view of this, three different transmission probability strategies are studied: optimal, fixed and adaptive. In this context, we also investigate cluster head selection schemes, specifically, we consider two intelligent schemes based on the fuzzy C-means and k-medoids algorithms and a random selection with no intelligence. We show that the use of intelligent schemes greatly improves the performance of the system, but their use entails higher complexity and selection delay. The main performance metrics considered in this work are energy consumption, successful transmission probability and cluster formation latency. As an additional feature of this work, we study the effect of errors in the wireless channel and the impact on the performance of the system under the different transmission probability schemes. PMID:29236065

[A case of cerebral fat embolism after artificial bone replacement operation for femoral head fracture].

PubMed

Kontani, Satoru; Nakamura, Akinobu; Tokumi, Hiroshi; Hirose, Genjirou

2014-01-01

A 83 years old woman was slipped and injured with right femoral neck fracture. After three days from the fracture, she underwent an artificial head bone replacement operation. Immediately after surgery, she complained of chest discomfort, nausea and dyspnea. A few hours later, she became comatose. Brain CT showed no abnormality and clinical diagnosis of heart failure was made without pulmonary embolism on enhanced chest CT. Magnetic resonance imaging (MRI) of the brain next day showed multiple small patchy hyperintense lesion in bilateral hemispheres on diffusion-weighted images (DWI), producing a "star field pattern''. Based on Criteria of Gurd, this patient had one major criterion and four minor criteria. And according to the Criteria of Schonfeld, this patient had 5 points, consistent with clinical diagnosis of fat embolism. Because of these criteria, she was diagnosed as cerebral fat embolism syndrome. We started supported care and edaravon. Two weeks after surgery, her condition recovered and remaind to stuporous state even six month after surgery. We experienced a typical case of cerebral fat embolism, after bone surgery with diagnostic findings on MRI-DWI. Diagnosis of cerebral fat embolism syndrome requires a history of long bone fracture and/or replacing surgery with typical finding on MRI images, such as "star field pattern''.

Time-to-Passage Judgments in Nonconstant Optical Flow Fields

NASA Technical Reports Server (NTRS)

Kaiser, Mary K.; Hecht, Heiko

1995-01-01

The time until an approaching object will pass an observer (time to passage, or TTP) is optically specified by a global flow field even in the absence of local expansion or size cues. Kaiser and Mowafy have demonstrated that observers are in fact sensitive to this global flow information. The present studies investigate two factors that are usually ignored in work related to TTP: (1) non-constant motion functions and (2) concomitant eye rotation. Non-constant velocities violate an assumption of some TTP derivations, and eye rotations may complicate heading extraction. Such factors have practical significance, for example, in the case of a pilot accelerating an aircraft or executing a roll. In our studies, a flow field of constant-sized stars was presented monocularly on a large screen. TIP judgments had to be made on the basis of one target star. The flow field varied in its acceleration pattern and its roll component. Observers did not appear to utilize acceleration information. In particular, TTP with decelerating motion were consistently underestimated. TTP judgments were fairly robust with respect to roll, even when roll axis and track vector were decoupled. However, substantial decoupling between heading and track vector led to a decrement in performance, in both the presence and the absence of roll.

The sudden appearance of CO emission in LHA 115-S 65

NASA Astrophysics Data System (ADS)

Oksala, M. E.; Kraus, M.; Arias, M. L.; Borges Fernandes, M.; Cidale, L.; Muratore, M. F.; Curé, M.

2012-10-01

Molecular emission has been detected in several Magellanic Cloud B[e] supergiants. In this Letter, we report on the detection of CO band head emission in the B[e] supergiant LHA 115-S 65, and present a K-band near-infrared spectrum obtained with the Spectrograph for INtegral Field Observation in the Near-Infrared (SINFONI; R= 4500) on the ESO VLT UT4 telescope. The observed molecular band head emission in S65 is quite surprising in the light of a previous non-detection by McGregor, Hyland & McGinn, as well as a high-resolution (R= 50 000) Gemini/Phoenix spectrum of this star taken nine months earlier showing no emission. Based on analysis of the optical spectrum by Kraus, Borges Fernandes & de Araújo, we suspect that the sudden appearance of molecular emission could be due to density build-up in an outflowing viscous disc, as seen for Be stars. This new discovery, combined with variability in two other similar evolved massive stars, indicates an evolutionary link between B[e] supergiants and luminous blue variables. Based on observations obtained with ESO telescopes at the La Silla Paranal Observatory under programme ID 088.D-044 and at the Gemini Observatory which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (USA), the Science and Technology Facilities Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), under programme ID GS-2010B-Q-31.

Digital live-tracking 3-dimensional minisensors for recording head orientation during image acquisition.

PubMed

de Paula, Leonardo Koerich; Ackerman, James L; Carvalho, Felipe de Assis Ribeiro; Eidson, Lindsey; Cevidanes, Lucia Helena Soares

2012-01-01

Our objective was to test the value of minisensors for recording unrestrained head position with 6 degrees of freedom during 3-dimensional stereophotogrammetry. Four 3-dimensional pictures (3dMD, Atlanta, Ga) were taken of 20 volunteers as follows: (1) in unrestrained head position, (2) a repeat of picture 1, (3) in unrestrained head position wearing a headset with 3-dimensional live tracking sensors (3-D Guidance trackSTAR; Ascension Technology, Burlington, Vt), and (4) a repeat of picture 3. The sensors were used to track the x, y, and z coordinates (pitch, roll, and yaw) of the head in space. The patients were seated in front of a mirror and asked to stand and take a walk between each acquisition. Eight landmarks were identified in each 3-dimensional picture (nasion, tip of nose, subnasale, right and left lip commissures, midpoints of upper and lower lip vermilions, soft-tissue B-point). The distances between correspondent landmarks were measured between pictures 1 and 2 and 3 and 4 with software. The Student t test was used to test differences between unrestrained head position with and without sensors. Interlandmark distances for pictures 1 and 2 (head position without the sensors) and pictures 3 and 4 (head position with sensors) were consistent for all landmarks, indicating that roll, pitch, and yaw of the head are controlled independently of the sensors. However, interlandmark distances were on average 17.34 ± 0.32 mm between pictures 1 and 2. Between pictures 3 and 4, the distances averaged 6.17 ± 0.15 mm. All interlandmark distances were significantly different between the 2 methods (P <0.001). The use of 3-dimensional live-tracking sensors aids the reproducibility of patient head positioning during repeated or follow-up acquisitions of 3-dimensional stereophotogrammetry. Even with sensors, differences in spatial head position between acquisitions still require additional registration procedures. Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Evolution of brains and behavior for optimal foraging: A tale of two predators

PubMed Central

Catania, Kenneth C.

2012-01-01

Star-nosed moles and tentacled snakes have exceptional mechanosensory systems that illustrate a number of general features of nervous system organization and evolution. Star-nosed moles use the star for active touch—rapidly scanning the environment with the nasal rays. The star has the densest concentration of mechanoreceptors described for any mammal, with a central tactile fovea magnified in anatomically visible neocortical modules. The somatosensory system parallels visual system organization, illustrating general features of high-resolution sensory representations. Star-nosed moles are the fastest mammalian foragers, able to identify and eat small prey in 120 ms. Optimal foraging theory suggests that the star evolved for profitably exploiting small invertebrates in a competitive wetland environment. The tentacled snake’s facial appendages are superficially similar to the mole’s nasal rays, but they have a very different function. These snakes are fully aquatic and use tentacles for passive detection of nearby fish. Trigeminal afferents respond to water movements and project tentacle information to the tectum in alignment with vision, illustrating a general theme for the integration of different sensory modalities. Tentacled snakes act as rare enemies, taking advantage of fish C-start escape responses by startling fish toward their strike—often aiming for the future location of escaping fish. By turning fish escapes to their advantage, snakes increase strike success and reduce handling time with head-first captures. The latter may, in turn, prevent snakes from becoming prey when feeding. Findings in these two unusual predators emphasize the importance of a multidisciplinary approach for understanding the evolution of brains and behavior. PMID:22723352

Space Science

NASA Image and Video Library

2002-04-02

Resembling a nightmarish beast rearing its head from a crimson sea, this monstrous object is actually an irnocuous pillar of gas and dust. Called the Cone Nebula (NGC 2264), this giant pillar resides in a turbulent star-forming region. This picture, taken by the newly installed Advanced Camera for Surveys (ACS) aboard Hubble Space Telescope (HST) during Space Shuttle STS-109 mission in March 2002, shows the upper 2.5 light-years of the nebula, a height that equals 23 million roundtrips to the Moon. The entire nebula is 7 light-years long. The Cone Nebula resides 2,500 light-years away in the constellation Monoceros. Radiation from hot, young stars (located beyond the top of the image) has slowly eroded the nebula over millions of years. Ultraviolet light heats the edges of the dark cloud, releasing gas into the relatively empty region of surrounding space. There, additional ultraviolet radiation causes the hydrogen gas to glow, which produces the red halo of light seen around the pillar. A similar process occurs on a much smaller scale to gas surrounding a single star, forming the bow-shaped arc seen near the upper left side of the Cone. This arc, seen previously with the HST, is 65 times larger than the diameter of our solar system. The blue-white light from surrounding stars is reflected by dust. Background stars can be seen peeking through the evaporating tendrils of gas, while the turbulent base is pockmarked with stars reddened by dust. Credit: NASA, H. Ford (JHU), G. Illingworth (USCS/LO), M. Clampin (STScI), G. Hartig (STScI), the ACS Science Team, and ESA.

The Palomar Testbed Interferometer

NASA Technical Reports Server (NTRS)

Colavita, M. M.; Wallace, J. K.; Hines, B. E.; Gursel, Y.; Malbet, F.; Palmer, D. L.; Pan, X. P.; Shao, M.; Yu, J. W.; Boden, A. F.

1999-01-01

The Palomar Testbed Interferometer (PTI) is a long-baseline infrared interferometer located at Palomar Observatory, California. It was built as a testbed for interferometric techniques applicable to the Keck Interferometer. First fringes were obtained in 1995 July. PTI implements a dual-star architecture, tracking two stars simultaneously for phase referencing and narrow-angle astrometry. The three fixed 40 cm apertures can be combined pairwise to provide baselines to 110 m. The interferometer actively tracks the white-light fringe using an array detector at 2.2 microns and active delay lines with a range of +/-38 m. Laser metrology of the delay lines allows for servo control, and laser metrology of the complete optical path enables narrow-angle astrometric measurements. The instrument is highly automated, using a multiprocessing computer system for instrument control and sequencing.

Nuclear pasta phases within the quark-meson coupling model

NASA Astrophysics Data System (ADS)

Grams, Guilherme; Santos, Alexandre M.; Panda, Prafulla K.; Providência, Constança; Menezes, Débora P.

2017-05-01

In this work, the low-density regions of nuclear and neutron star matter are studied. The search for the existence of nuclear pasta phases in this region is performed within the context of the quark-meson coupling (QMC) model, which incorporates quark degrees of freedom. Fixed proton fractions are considered, as well as nuclear matter in β equilibrium at zero temperature. We discuss the recent attempts to better understand the surface energy in the coexistence phases regime and we present results that show the existence of the pasta phases subject to some choices of the surface energy coefficient. We also analyze the influence of the nuclear pasta on some neutron star properties. The equation of state containing the pasta phase will be part of a complete grid for future use in supernova simulations.

Optimal estimation for the satellite attitude using star tracker measurements

NASA Technical Reports Server (NTRS)

Lo, J. T.-H.

1986-01-01

An optimal estimation scheme is presented, which determines the satellite attitude using the gyro readings and the star tracker measurements of a commonly used satellite attitude measuring unit. The scheme is mainly based on the exponential Fourier densities that have the desirable closure property under conditioning. By updating a finite and fixed number of parameters, the conditional probability density, which is an exponential Fourier density, is recursively determined. Simulation results indicate that the scheme is more accurate and robust than extended Kalman filtering. It is believed that this approach is applicable to many other attitude measuring units. As no linearization and approximation are necessary in the approach, it is ideal for systems involving high levels of randomness and/or low levels of observability and systems for which accuracy is of overriding importance.

Astronauts and Cosmonauts sightseeing at Red Square in Moscow

NASA Technical Reports Server (NTRS)

1974-01-01

A group of Astronauts and their Cosmonaut hosts are photographed sightseeing on Red Square in the heart of Moscow during a tour of the Soviet capital. The Americans were in the USSR to participate in Apollo Soyuz Test Project (ASTP) familiarization training on the Soyuz systems at the Cosmonaut Training Center (Star City) near Moscow. Astronaut Thomas P. Stafford (light coat, black cap), commander of the American ASTP crew, was head of the U.S. delegation to Star City. Astronaut Eugene A. Cernan (on Stafford's left, light coat) is the Special Assistant to the American Technical Director of ASTP. The sightseeing group is walking in the direction of Lenin's Mausoleum. The structure in the background is the Cathedral of the Intercession (St. Basil's) Museum. The historic Kremlin complex is to the right.

Effects of Extreme Obliquity Variations on the Habitability of Exoplanets

PubMed Central

Barnes, R.; Domagal-Goldman, S.; Breiner, J.; Quinn, T.R.; Meadows, V.S.

2014-01-01

Abstract We explore the impact of obliquity variations on planetary habitability in hypothetical systems with high mutual inclination. We show that large-amplitude, high-frequency obliquity oscillations on Earth-like exoplanets can suppress the ice-albedo feedback, increasing the outer edge of the habitable zone. We restricted our exploration to hypothetical systems consisting of a solar-mass star, an Earth-mass planet at 1 AU, and 1 or 2 larger planets. We verified that these systems are stable for 108 years with N-body simulations and calculated the obliquity variations induced by the orbital evolution of the Earth-mass planet and a torque from the host star. We ran a simplified energy balance model on the terrestrial planet to assess surface temperature and ice coverage on the planet's surface, and we calculated differences in the outer edge of the habitable zone for planets with rapid obliquity variations. For each hypothetical system, we calculated the outer edge of habitability for two conditions: (1) the full evolution of the planetary spin and orbit and (2) the eccentricity and obliquity fixed at their average values. We recovered previous results that higher values of fixed obliquity and eccentricity expand the habitable zone, but we also found that obliquity oscillations further expand habitable orbits in all cases. Terrestrial planets near the outer edge of the habitable zone may be more likely to support life in systems that induce rapid obliquity oscillations as opposed to fixed-spin planets. Such planets may be the easiest to directly characterize with space-borne telescopes. Key Words: Exoplanets—Habitable zone—Energy balance models. Astrobiology 14, 277–291. PMID:24611714

A Reward-Based Behavioral Platform to Measure Neural Activity during Head-Fixed Behavior.

PubMed

Micallef, Andrew H; Takahashi, Naoya; Larkum, Matthew E; Palmer, Lucy M

2017-01-01

Understanding the neural computations that contribute to behavior requires recording from neurons while an animal is behaving. This is not an easy task as most subcellular recording techniques require absolute head stability. The Go/No-Go sensory task is a powerful decision-driven task that enables an animal to report a binary decision during head-fixation. Here we discuss how to set up an Ardunio and Python based platform system to control a Go/No-Go sensory behavior paradigm. Using an Arduino micro-controller and Python-based custom written program, a reward can be delivered to the animal depending on the decision reported. We discuss the various components required to build the behavioral apparatus that can control and report such a sensory stimulus paradigm. This system enables the end user to control the behavioral testing in real-time and therefore it provides a strong custom-made platform for probing the neural basis of behavior.

Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components

NASA Technical Reports Server (NTRS)

Campbell, J. E.

1971-01-01

Data showing that 90 C was a more effective temperature than 125 C for the destruction of Bacillus subtilis var. niger when the head-space moisture was fixed at 474 micrograms H2O/ml have been confirmed and are summarized. The influence of head-space moisture at 90 C was investigated and it was observed that as the head-space moisture was increased 474 micrograms H2O/ml, there was a corresponding increase in lethality of the system. This moisture level corresponded to 100% relative humidity at 90 C, and additional water in the cans should have had no effect. A profound descrease was observed in the destruction of the organisms when additional water was added. The discontinuity observed in these data is troublesome and must be resolved as the first step in an orderly exploration of low temperature inactivation of B. subtilis var. niger.

Tonic cervical influences on eye nystagmus following hemilabyrinthectomy: immediate and plastic effects.

PubMed

Pettorossi, V E; Petrosini, L

1984-12-17

In intact guinea pigs a passive horizontal rotation of the body about the fixed head induces compensatory ocular movements (cervico-ocular reflex). When the static neck deviation is maintained, a significant ocular displacement is observed. In acutely hemilabyrinthectomized animals, static body deviation towards the lesion side tonically alters eye nystagmus. It affects slow phase eye velocity and quick phase amplitude and frequency causing the eye to reach a less eccentric orbital position. Apart from such immediate influences, a plastic effect on eye nystagmus abatement is induced. In the animals restrained with no body-on-head deviation, abatement of nystagmus is delayed with respect to the animals restrained with 35 degrees body deviation towards the lesion side. Thus the head position signal is not only a contributing factor for the correction of postural deficits but also influences the time course of the ocular balancing process following unilateral vestibular damage.

Exploring properties of high-density matter through remnants of neutron-star mergers

NASA Astrophysics Data System (ADS)

Bauswein, Andreas; Stergioulas, Nikolaos; Janka, Hans-Thomas

2016-03-01

Remnants of neutron-star mergers are essentially massive, hot, differentially rotating neutron stars, which are initially strongly oscillating. As such they represent a unique probe for high-density matter because the oscillations are detectable via gravitational-wave measurements and are strongly dependent on the equation of state. The impact of the equation of state for instance is apparent in the frequency of the dominant oscillation mode of the remnant. For a fixed total binary mass a tight relation between the dominant postmerger oscillation frequency and the radii of nonrotating neutron stars exists. Inferring observationally the dominant postmerger frequency thus determines neutron star radii with high accuracy of the order of a few hundred meters. By considering symmetric and asymmetric binaries of the same chirp mass, we show that the knowledge of the binary mass ratio is not critical for this kind of radius measurements. We perform simulations which show that initial intrinsic neutron star rotation is unlikely to affect this method of constraining the high-density equation of state. We also summarize different possibilities about how the postmerger gravitational-wave emission can be employed to deduce the maximum mass of nonrotating neutron stars. We clarify the nature of the three most prominent features of the postmerger gravitational-wave spectrum and argue that the merger remnant can be considered to be a single, isolated, self-gravitating object that can be described by concepts of asteroseismology. We sketch how the consideration of the strength of secondary gravitational-wave peaks leads to a classification scheme of the gravitational-wave emission and postmerger dynamics. The understanding of the different mechanisms shaping the gravitational-wave signal yields a physically motivated analytic model of the gravitational-wave emission, which may form the basis for template-based gravitational-wave data analysis. We explore the observational consequences of a scenario of two families of compact stars including hadronic and quark matter stars. We find that this scenario leaves a distinctive imprint on the postmerger gravitational-wave signal. In particular, a strong discontinuity in the dominant postmerger frequency as function of the total mass will be a strong indication for two families of compact stars.

CENTIMETER CONTINUUM OBSERVATIONS OF THE NORTHERN HEAD OF THE HH 80/81/80N JET: REVISING THE ACTUAL DIMENSIONS OF A PARSEC-SCALE JET

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

Masque, Josep M.; Estalella, Robert; Girart, Josep M.

2012-10-10

We present 6 and 20 cm Jansky Very Large Array/Very Large Array observations of the northern head of the HH 80/81/80N jet, one of the largest collimated jet systems known so far, aimed to look for knots farther than HH 80N, the northern head of the jet. Aligned with the jet and 10' northeast of HH 80N, we found a radio source not reported before, with a negative spectral index similar to that of HH 80, HH 81, and HH 80N. The fit of a precessing jet model to the knots of the HH 80/81/80N jet, including the new source,more » shows that the position of this source is close to the jet path resulting from the modeling. If the new source belongs to the HH 80/81/80N jet, its derived size and dynamical age are 18.4 pc and >9 Multiplication-Sign 10{sup 3} yr, respectively. If the jet is symmetric, its southern lobe would expand beyond the cloud edge resulting in an asymmetric appearance of the jet. Based on the updated dynamical age, we speculate on the possibility that the HH 80/81/80N jet triggered the star formation observed in a dense core found ahead of HH 80N, which shows signposts of interaction with the jet. These results indicate that parsec-scale radio jets can play a role in the stability of dense clumps and the regulation of star formation in the molecular cloud.« less

Rozhdenie antichnoj astrometrii %t The birth of ancient astrometry

NASA Astrophysics Data System (ADS)

Zhitomirskij, S. V.

In this article, the most probable reasons that stimulated the instrumental observations of celestial bodies are considered. In the 5th century B.C., the first stage of such observations was connected with the calendar: the measuring of the ecliptic obliquity by Oinopidus of Chios, introduction of the 19-year calendar cycle by Meton, and the discovery of inequality of the astronomic seasons by Euctemon. It is shown in the article that Euctemon defined fairly accurately time of the solstices. The theory of planet movements created in the 4th century B.C. by Eudoxus and Callipus postulated backward movements of planets along the "hippopede". This theory became a kind of challenge for the observers. In the 3rd Century B.C., Timocharis determined the equatorial coordinates of 12 stars. It is shown that those stars are connected with both the ecliptic and the equator and served possibly as points of reference in planet observations. Such observations, if they were conducted, would have shown that the planets do not follow the "hippopedes", but loop-like curves. In the same century, probably under the influence of the observational data, new theories of planet motion appeared: the heliocentric hypothesis of Aristarhus of Samos. Archimedes' geoheliocentric theory, and the theorem of similarity of excentral and epicyclical planet motion by Apollonius of Perga. In the next century, Hipparchus compiled the first Star Catalogue in history. The reason for the first mass measuring of star coordinates was the criticism of the sphere description according to Eudoxus and Aratus, because of the difference between the description of the star position and the actual observations. As to the reasons for the creation of the Star Catalogue itself, they were possibly the discovery of precession by Hipparchus, which required understanding of the character of movement of fixed stars, and the appearance of a new star in the constellation of Scorpius.

GOODS-HERSCHEL: STAR FORMATION, DUST ATTENUATION, AND THE FIR–RADIO CORRELATION ON THE MAIN SEQUENCE OF STAR-FORMING GALAXIES UP TO z ≃ 4

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

Pannella, M.; Elbaz, D.; Daddi, E.

We use deep panchromatic data sets in the GOODS-N field, from GALEX to the deepest Herschel far-infrared (FIR) and VLA radio continuum imaging, to explore the evolution of star-formation activity and dust attenuation properties of star-forming galaxies to z ≃ 4, using mass-complete samples. Our main results can be summarized as follows: (i) the slope of the star-formation rate–M{sub *} correlation is consistent with being constant ≃0.8 up to z ≃ 1.5, while its normalization keeps increasing with redshift; (ii) for the first time we are able to explore the FIR–radio correlation for a mass-selected sample of star-forming galaxies: themore » correlation does not evolve up to z ≃ 4; (iii) we confirm that galaxy stellar mass is a robust proxy for UV dust attenuation in star-forming galaxies, with more massive galaxies being more dust attenuated. Strikingly, we find that this attenuation relation evolves very weakly with redshift, with the amount of dust attenuation increasing by less than 0.3 mag over the redshift range [0.5–4] for a fixed stellar mass; (iv) the correlation between dust attenuation and the UV spectral slope evolves with redshift, with the median UV slope becoming bluer with redshift. By z ≃ 3, typical UV slopes are inconsistent, given the measured dust attenuations, with the predictions of commonly used empirical laws. (v) Finally, building on existing results, we show that gas reddening is marginally larger (by a factor of around 1.3) than the stellar reddening at all redshifts probed. Our results support a scenario where the ISM conditions of typical star-forming galaxies evolve with redshift, such that at z ≥ 1.5 Main Sequence galaxies have ISM conditions moving closer to those of local starbursts.« less

The Crowded Magnetosphere Of The Post-Common-Envelope Binary QS Virginis

NASA Astrophysics Data System (ADS)

Hill, Colin

2016-06-01

We present high-speed photometry and high-resolution spectroscopy of the short-period (Prot = 3.6 h) eclipsing post-common-envelope binary QS Virginis (QS Vir). Our UVES spectra span in excess of 6 orbits, over more than a year, and reveal the presence of several large prominences passing in front of both the M star and its white dwarf (WD) companion. Despite showing small variations on a time-scale of days, they persist for more than a year and may last decades. Roche tomography reveals a heavily spotted M star, with long-lived spots remaining in fixed locations, preferentially found on the hemisphere facing the WD. We find the 14,220 ± 350 K WD is relatively massive at 0.782 ± 0.013 M(_{odot}),with a radius of0.01068 ± 0.00007 R(_{odot}), consistent with evolutionary models. The tidally distorted M star has a mass of 0.382 ± 0.006 M(_{odot})and a radius of0.381 ± 0.003 R(_{odot}), also consistent with evolutionary models. Since the M star's radius is still within its Roche lobe and there is no evidence that it is overinflated, we conclude that QS Vir is most likely a pre-cataclysmic binary just about to become semidetached.

STELLAR 'EGGS' EMERGE FROM MOLECULAR CLOUD (Star-Birth Clouds in M16)

NASA Technical Reports Server (NTRS)

2002-01-01

This eerie, dark structure, resembling an imaginary sea serpent's head, is a column of cool molecular hydrogen gas (two atoms of hydrogen in each molecule) and dust that is an incubator for new stars. The stars are embedded inside finger-like protrusions extending from the top of the nebula. Each 'fingertip' is somewhat larger than our own solar system. The pillar is slowly eroding away by the ultraviolet light from nearby hot stars, a process called 'photoevaporation'. As it does, small globules of especially dense gas buried within the cloud is uncovered. These globules have been dubbed 'EGGs' -- an acronym for 'Evaporating Gaseous Globules'. The shadows of the EGGs protect gas behind them, resulting in the finger-like structures at the top of the cloud. Forming inside at least some of the EGGs are embryonic stars -- stars that abruptly stop growing when the EGGs are uncovered and they are separated from the larger reservoir of gas from which they were drawing mass. Eventually the stars emerge, as the EGGs themselves succumb to photoevaporation. The stellar EGGS are found, appropriately enough, in the 'Eagle Nebula' (also called M16 -- the 16th object in Charles Messier's 18th century catalog of 'fuzzy' permanent objects in the sky), a nearby star-forming region 6,500 light-years away in the constellation Serpens. The picture was taken on April 1, 1995 with the Hubble Space Telescope Wide Field and Planetary Camera 2. The color image is constructed from three separate images taken in the light of emission from different types of atoms. Red shows emission from singly-ionized sulfur atoms. Green shows emission from hydrogen. Blue shows light emitted by doubly- ionized oxygen atoms. Credit: Jeff Hester and Paul Scowen (Arizona State University), and NASA Image files in GIF and JPEG format and captions may be accessed on Internet via anonymous ftp from oposite.stsci.edu in /pubinfo:

Sudden Radiative Braking in Colliding Hot-Star Winds

NASA Technical Reports Server (NTRS)

Gayley, K. G.; Owocki, S. P.; Cranmer, S. R.

1996-01-01

When two hot-star winds collide, their interaction centers at the point where the momentum fluxes balance. However, in WR+O systems, the imbalance in the corporeal momentum fluxes may be extreme enough to preclude a standard head-on wind/wind collision. On the other hand, an important component of the total momentum flux in radiatively driven winds is carried by photons. Thus, if the wind interaction region has sufficient scattering opacity, it can reflect stellar photons and cause important radiative terms to enter the momentum balance. This radiative input would result in additional braking of the wind. We use a radiative-hydrodynamics calculation to show that such radiative braking can be an important effect in many types of colliding hot-star winds. Characterized by sudden deceleration of the stronger wind in the vicinity of the weak-wind star, it can allow a wind ram balance that would otherwise be impossible in many WR+O systems with separations less than a few hundred solar radii. It also greatly weakens the shock strength and the encumbent X ray production. We demonstrate the significant features of this effect using V444 Cygni as a characteristic example. We also derive a general analytic theory that applies to a wide class of binaries, yielding simple predictions for when radiative braking should play an important role.

Winds in collision. II - An analysis of the X-ray emission from the eruptive symbiotic HM Sge

NASA Technical Reports Server (NTRS)

Willson, L. A.; Wallerstein, G.; Brugel, E. W.; Stencel, R. E.

1984-01-01

X-ray emissions from HM Sge obtained in 1981 from the HEAO-2 satellite are analyzed and compared quantitatively with observations of HM Sge made in 1980 and of HM Sge, V 1016 Cyg, and RR Tel made in 1979. The change in the X-ray emission from HM Sge between 1979 and 1981 is found to be consistent with the X-ray luminosity and/or temperature of the emitting region declining with an e-folding timescale of the order of one to several decades. Comparison with X-ray data from V 1016 Cyg and RR Tel gives a composite X-ray light curve that is also consistent with such a decline. A comparison of the X-ray observation with spectroscopic information makes it possible to constrain the properties of the X-ray emitting region: the result is consistent with emission from an optically thin region between the two stars in the system where their winds collide head on. It is also shown that the observations are inconsistent with a stellar (blackbody) source, with emission from an accretion disk around a white dwarf or a neutron star, and with emission from a single star wind from either a white dwarf or a neutron star.

Classifying and Standardizing Panfacial Trauma With a New Bony Facial Trauma Score.

PubMed

Casale, Garrett G A; Fishero, Brian A; Park, Stephen S; Sochor, Mark; Heltzel, Sara B; Christophel, J Jared

2017-01-01

The practice of facial trauma surgery would benefit from a useful quantitative scale that measures the extent of injury. To develop a facial trauma scale that incorporates only reducible fractures and is able to be reliably communicated to health care professionals. A cadaveric tissue study was conducted from October 1 to 3, 2014. Ten cadaveric heads were subjected to various degrees of facial trauma by dropping a fixed mass onto each head. The heads were then imaged with fine-cut computed tomography. A Bony Facial Trauma Scale (BFTS) for grading facial trauma was developed based only on clinically relevant (reducible) fractures. The traumatized cadaveric heads were then scored using this scale as well as 3 existing scoring systems. Regression analysis was used to determine correlation between degree of incursion of the fixed mass on the cadaveric heads and trauma severity as rated by the scoring systems. Statistical analysis was performed to determine correlation of the scores obtained using the BFTS with those of the 3 existing scoring systems. Scores obtained using the BFTS were not correlated with dentition (95% CI, -0.087 to 1.053; P = .08; measured as absolute number of teeth) or age of the cadaveric donor (95% CI, -0.068 to 0.944; P = .08). Facial trauma scores. Among all 10 cadaveric specimens (9 male donors and 1 female donor; age range, 41-87 years; mean age, 57.2 years), the facial trauma scores obtained using the BFTS correlated with depth of penetration of the mass into the face (odds ratio, 4.071; 95% CI, 1.676-6.448) P = .007) when controlling for presence of dentition and age. The BFTS scores also correlated with scores obtained using 3 existing facial trauma models (Facial Fracture Severity Scale, rs = 0.920; Craniofacial Disruption Score, rs = 0.945; and ZS Score, rs = 0.902; P < .001 for all 3 models). In addition, the BFTS was found to have excellent interrater reliability (0.908; P = .001), which was similar to the interrater reliability of the other 3 tested trauma scales. Scores obtained using the BFTS were not correlated with dentition (odds ratio, .482; 95% CI, -0.087 to 1.053; P = .08; measured as absolute number of teeth) or age of the cadaveric donor (odds ratio, .436; 95% CI, -0.068 to 0.944; P = .08). Facial trauma severity as measured by the BFTS correlated with depth of penetration of the fixed mass into the face. In this study, the BFTS was clinically relevant, had high fidelity in communicating the fractures sustained in facial trauma, and correlated well with previously validated models. NA.

Investigation of the effect of a bend in a transfer line that separates a pulse tube cold head and a pressure wave generator

NASA Astrophysics Data System (ADS)

Dev, A. A.; Atrey, M. D.; Vanapalli, S.

2017-02-01

A transfer line between a pulse tube cold head and a pressure wave generator is usually required to isolate the cold head from the vibrations of the compressor. Although it is a common practice to use a thin and narrow straight tube, a bent tube would allow design flexibility and easy mounting of the cold head, such as in a split Stirling type pulse tube cryocooler. In this paper, we report a preliminary investigation on the effect of the bending of the tube on the flow transfer characteristics. A numerical study using commercial computational fluid dynamics model is performed to gain insight into the flow characteristics in the bent tube. Oscillating flow experiments are performed with a straight and a bent tube at a filling pressure of 15 bar and an operating frequency of 40, 50 and 60 Hz. The data and the corresponding numerical simulations point to the hypothesis that the secondary flow in the bent tube causes a decrease in flow at a fixed pressure amplitude.

Otolithic and extraocular muscle proprioceptive influences on the spatial organization of the vestibulo- and cervico-ocular quick phases.

PubMed

Pettorossi, V E; Manni, E; Errico, P; Ferraresi, A; Bortolami, R

1997-03-01

The cervico-ocular reflex (COR) was studied alone or in combination with the vestibulo-ocular reflex (VOR) in the rabbit. Step stimulations of the body with respect to the fixed head induced small slow compensatory responses followed by large compensatory quick phases (QP). These responses remained aligned with the horizon at different head pitch angles. The QP reorientation in space was due to the gravity influence on the otolithic receptors. The vestibular induced QPs exhibit a similar pattern. Because of this reorientation, the reduction of the amplitude of the vestibular induced QPs, due to the addition of the COR, was maintained even at different static head positions. The electrolytic lesion of the ophthalmic branch of the trigeminal nerve deeply affected the space orientation of the COR. In particular, the cervically induced compensatory QPs of the eye ipsilateral to the lesion showed a remarkable variability of their trajectories and they lost space reorientation. These findings suggest that the coordinate system controlling the QPs is influenced by signals originating from both head position in space and eye position in the orbit.

Synthetic Vision Enhanced Surface Operations With Head-Worn Display for Commercial Aircraft

NASA Technical Reports Server (NTRS)

Arthur, Jarvis J., III; Prinzel, Lawrence J., III; Shelton, Kevin J.; Kramer, Lynda J.; Williams, Steven P.; Bailey, Randall E.; Norman, R. M.

2007-01-01

Experiments and flight tests have shown that airport surface operations can be enhanced by using synthetic vision and associated technologies, employed on a Head-Up Display (HUD) and head-down display electronic moving maps (EMM). Although HUD applications have shown the greatest potential operational improvements, the research noted that two major limitations during ground operations were its monochrome form and limited, fixed field-of-regard. A potential solution to these limitations may be the application of advanced Head Worn Displays (HWDs) particularly during low-visibility operations wherein surface movement is substantially limited because of the impaired vision of pilots and air traffic controllers. The paper describes the results of ground simulation experiments conducted at the NASA Langley Research Center. The results of the experiments showed that the fully integrated HWD concept provided significantly improved path performance compared to using paper charts alone. When comparing the HWD and HUD concepts, there were no statistically-significant differences in path performance or subjective ratings of situation awareness and workload. Implications and directions for future research are described.

Temperature compensated liquid level sensor using FBGs and a Bourdon tube

NASA Astrophysics Data System (ADS)

Sengupta, D.; Shankar, M. Sai; Rao, P. Vengal; Reddy, P. Saidi; Sai Prasad, R. L. N.; Kishore, P.; Srimannarayana, K.

2011-12-01

A temperature compensated liquid level sensor using FBGs and a bourdon tube that works on hydrostatic pressure is presented. An FBG (FBG1) is fixed between free end and a fixed end of the bourdon tube. When hydrostatic pressure applied to the bourdon tube FBG1 experience an axial strain due to the movement of free end. Experimental result shows, a good linearity in shift in Bragg wavelength with the applied pressure. The performance of this arrangement is tested for 21metre water column pressure. Another FBG (FBG2) is included for temperature compensation. The design of the sensor head is simple and easy mountable external to any tank for liquid level measurements.

Stars and their Environments at High-Resolution with IGRINS

NASA Astrophysics Data System (ADS)

Mace, Gregory; Jaffe, Daniel; Kaplan, Kyle; Kidder, Benjamin; Oh, Heeyoung; Sneden, Christopher; Afşar, Melike

2016-06-01

TheImmersion Grating Infrared Spectrometer (IGRINS) is a revolutionary instrument that exploits broad spectral coverage at high-resolution in the near-infrared. There are no moving parts in IGRINS and its high-throughput white-pupil design maximizes sensitivity. IGRINS on the 2.7 meter Harlan J. Smith Telescope at McDonald Observatory is nearly as sensitive as CRIRES at the 8 meter Very Large Telescope. However, IGRINS at R=45,000 has more than 30 times the spectral grasp of CRIRES. The use of an immersion grating facilitates a compact cryostat while providing simultaneous H and K band observations with complete wavelength coverage from 1.45 - 2.45 microns. Here we discuss details of instrument performance and summarize the application of IGRINS to stellar characterization, star formation in regions like Taurus and Ophiuchus, the interstellar medium, and photodissociation regions. IGRINS has the largest spectral grasp of any high-resolution, near-infrared spectrograph, allowing us to study star formation and evolution in unprecedented detail. With its fixed format and high sensitivity, IGRINS is a great survey instrument for star clusters, high signal-to-noise (SNR>300) studies of field stars, and for mapping the interstellar medium. As a prototype for GMTNIRS on the Giant Magellan Telescope, IGRINS represents the future of high-resolution spectroscopy. In the future IGRINS will be deployed to numerous facilities and will remain a versatile instrument for the community while producing a rich archive of uniform spectra.

Using neutron star observations to determine crust thicknesses, moments of inertia, and tidal deformabilities

DOE PAGES

Steiner, A. W.; Gandolfi, S.; Fattoyev, F. J.; ...

2015-01-13

Here, we perform a systematic assessment of models for the equation of state (EOS) of dense matter in the context of recent neutron star mass and radius measurements to obtain a broad picture of the structure of neutron stars. We demonstrate that currently available neutron star mass and radius measurements provide strong constraints on moments of inertia, tidal deformabilities, and crust thicknesses. Moreover, a measurement of the moment of inertia of PSR J0737-3039A with a 10% error, without any other information from observations, will constrain the EOS over a range of densities to within 50% 60%. We find tidal deformabilitiesmore » between 0.6 and 6 1036 g cm 2 s 2 (to 95% confidence) for M = 1.4 M ⊙ , and any measurement which constrains this range will provide an important constraint on dense matter. The crustal fraction of the moment of inertia can be as large as 10% for M = 1.4 M ⊙ permitting crusts to have a large enough moment of inertia reservoir to explain glitches in the Vela pulsar even with a large amount of superfluid entrainment. Finally, due to the uncertainty in the equation of state, there is at least a 40% variation in the thickness of the crust for a fixed mass and radius, which implies that future simulations of the cooling of a neutron star crust which has been heated by accretion will need to take this variation into account.« less

47 CFR 101.77 - Public safety licensees in the 1850-1990 MHz, 2110-2150 MHz, and 2160-2200 MHz bands.

Code of Federal Regulations, 2014 CFR

2014-10-01

...-1990 MHz, 2110-2150 MHz, and 2160-2200 MHz bands. (a) In order for public safety licensees to qualify for a three year mandatory negotiation period as defined in § 101.69(d)(2), the department head... COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Applications and Licenses...

47 CFR 101.77 - Public safety licensees in the 1850-1990 MHz, 2110-2150 MHz, and 2160-2200 MHz bands.

Code of Federal Regulations, 2012 CFR

2012-10-01

...-1990 MHz, 2110-2150 MHz, and 2160-2200 MHz bands. (a) In order for public safety licensees to qualify for a three year mandatory negotiation period as defined in § 101.69(d)(2), the department head... COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Applications and Licenses...

47 CFR 101.77 - Public safety licensees in the 1850-1990 MHz, 2110-2150 MHz, and 2160-2200 MHz bands.

Code of Federal Regulations, 2013 CFR

2013-10-01

...-1990 MHz, 2110-2150 MHz, and 2160-2200 MHz bands. (a) In order for public safety licensees to qualify for a three year mandatory negotiation period as defined in § 101.69(d)(2), the department head... COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Applications and Licenses...

47 CFR 101.77 - Public safety licensees in the 1850-1990 MHz, 2110-2150 MHz, and 2160-2200 MHz bands.

Code of Federal Regulations, 2011 CFR

2011-10-01

...-1990 MHz, 2110-2150 MHz, and 2160-2200 MHz bands. (a) In order for public safety licensees to qualify for a three year mandatory negotiation period as defined in § 101.69(d)(2), the department head... COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Applications and Licenses...

Electronic Combat Hardware-in-the-Loop Testing in an Open Air Environment

DTIC Science & Technology

1994-09-01

APQ- 126 (F-111) Gun Dish Squat Eye ANAWG-9 (F-14) Grill Pan Straight Flush I-Hawk Hawk Screech Sun Visor Head Light Tall King High Fix Team Work High...the required delay to the IF, the SPCs contain a Teledyne Microwave Bulk Acoustic Wave (BAW) delay line as well as a Coherent Variable Delay Unit

The KMOS Deep Survey: Dynamical Measurements of Star-Forming Galaxies at z 3.5

NASA Astrophysics Data System (ADS)

Turner, Owen; Cirasuolo, Michele; Harrison, Chris; McLure, Ross; Dunlop, James; Swinbank, Mark; Johnson, Helen; Sobral, David; Matthee, Jorryt; Sharples, Ray

2017-07-01

This poster present dynamical measurements from the KMOS (K-band Multi-Object Spectrograph) Deep Survey (KDS), which is comprised of 78 typical star-forming galaxies at z = 3.5 in the mass range 9.0 < log(M*) < 10.5. We fit spatially and spectrally convolved mock datacubes to the observed data, in order to make beam-smearing corrected measurements of the intrinsic velocity dispersions and rotation velocities of 33 galaxies in the sample classed as spatially resolved and isolated. The results suggest that the rotation-dominated galaxies in the sample are offset to lower velocities at fixed stellar mass and have higher velocity dispersions than star-forming galaxies in the local and intermediate redshift universe. Only 1/3 of the galaxies in the sample are dominated by rotation, which hints that random motions are playing an increasingly significant role in supporting the dynamical mass in the systems. When searching for evolution in scaling relations, such as the stellar mass Tully-Fisher relation, it is important to take these random motions into account.

A Very Liquid Heaven: An exhibit exploring the human perception of stars

NASA Astrophysics Data System (ADS)

Crone, M. M.

2004-12-01

This year the Tang Teaching Museum and Art Gallery at Skidmore College is showing an exhibit about the human perception of stars, accompanied by a catalog, a speaker series, and an outreach program. The exhibit includes historical documents and atlases as well as work by a variety of artists and scientists. A Very Liquid Heaven opened with a performance of George Crumb's musical piece Makrokosmos III surrounded by original dance, theater, and video art. The title of the exhibit is inspired by Rene Descartes' 1644 text Principles of Philosophy, where he describes the earth as "surrounded on all sides by a very liquid heaven." Although Isaac Newton's laws of mechanics and gravity later discredited his specific hypothesis, in a sense Descartes was correct: astronomy has indeed revealed stars not as hard, fixed objects, but as pulsing plasmas, and interstellar space not as a pure void, but as diffuse clouds of atoms and molecules. This exhibit is made possible with support from Beverly P. and R. Lawrence St. Clair, the Nathalie Potter Voorhees '45 Memorial fund, and the Friends of the Tang.

Search for continuous gravitational waves from neutron stars in globular cluster NGC 6544

NASA Astrophysics Data System (ADS)

Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Allen, B.; Allocca, A.; Altin, P. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Bejger, M.; Bell, A. S.; Berger, B. K.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Birney, R.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Boer, M.; Bogaert, G.; Bogan, C.; Bohe, A.; Bond, C.; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Broida, J. E.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerboni Baiardi, L.; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Cheeseboro, B. D.; Chen, H. Y.; Chen, Y.; Cheng, C.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M.; Conte, A.; Conti, L.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Creighton, T.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Darman, N. S.; Dasgupta, A.; Da Silva Costa, C. F.; Dattilo, V.; Dave, I.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; De, S.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Devine, R. C.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Virgilio, A.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Ducrot, M.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Engels, W.; Essick, R. C.; Etzel, T.; Evans, M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Fenyvesi, E.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H. A. G.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gaur, G.; Gehrels, N.; Gemme, G.; Geng, P.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gordon, N. A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Hall, B. R.; Hall, E. D.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Henry, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hofman, D.; Holt, K.; Holz, D. E.; Hopkins, P.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huang, S.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Ingram, D. R.; Inta, R.; Isa, H. N.; Isac, J.-M.; Isi, M.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jang, H.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jian, L.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Haris, K.; Kalaghatgi, C. V.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kapadia, S. J.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kéfélian, F.; Kehl, M. S.; Keitel, D.; Kelley, D. B.; Kells, W.; Kennedy, R.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chi-Woong; Kim, Chunglee; Kim, J.; Kim, K.; Kim, N.; Kim, W.; Kim, Y.-M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kissel, J. S.; Klein, B.; Kleybolte, L.; Klimenko, S.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Krishnan, B.; Królak, A.; Krueger, C.; Kuehn, G.; Kumar, P.; Kumar, R.; Kuo, L.; Kutynia, A.; Lackey, B. D.; Landry, M.; Lange, J.; Lantz, B.; Lasky, P. D.; Laxen, M.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, K.; Lenon, A.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Lewis, J. B.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Lockerbie, N. A.; Lombardi, A. L.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lück, H.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña-Sandoval, F.; Magaña Zertuche, L.; Magee, R. M.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martynov, D. V.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Melatos, A.; Mendell, G.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, A.; Miller, B. B.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B. C.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Murphy, D. J.; Murray, P. G.; Mytidis, A.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Nedkova, K.; Nelemans, G.; Nelson, T. J. N.; Neri, M.; Neunzert, A.; Newton, G.; Nguyen, T. T.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patel, P.; Patricelli, B.; Patrick, Z.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perreca, A.; Perri, L. M.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poe, M.; Poggiani, R.; Popolizio, P.; Post, A.; Powell, J.; Prasad, J.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Qin, J.; Qiu, S.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rakhmanov, M.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Read, J.; Reed, C. M.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Reyes, S. D.; Ricci, F.; Riles, K.; Rizzo, M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sanchez, E. J.; Sandberg, V.; Sandeen, B.; Sanders, J. R.; Sassolas, B.; Saulson, P. R.; Sauter, O. E. S.; Savage, R. L.; Sawadsky, A.; Schale, P.; Schilling, R.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, S. M.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Setyawati, Y.; Shaddock, D. A.; Shaffer, T.; Shahriar, M. S.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Singer, A.; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, J. R.; Smith, N. D.; Smith, R. J. E.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stone, R.; Strain, K. A.; Straniero, N.; Stratta, G.; Strauss, N. A.; Strigin, S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tápai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, R.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tomlinson, C.; Tonelli, M.; Tornasi, Z.; Torres, C. V.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trifirò, D.; Tringali, M. C.; Trozzo, L.; Tse, M.; Turconi, M.; Tuyenbayev, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D. V.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, M.; Wang, X.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Weßels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whiting, B. F.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Worden, J.; Wright, J. L.; Wu, D. S.; Wu, G.; Yablon, J.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yu, H.; Yvert, M.; ZadroŻny, A.; Zangrando, L.; Zanolin, M.; Zendri, J.-P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, X. J.; Zucker, M. E.; Zuraw, S. E.; Zweizig, J.; Sigurdsson, S.; LIGO Scientific Collaboration; Virgo Collaboration

2017-04-01

We describe a directed search for continuous gravitational waves in data from the sixth initial LIGO science run. The target was the nearby globular cluster NGC 6544 at a distance of ≈2.7 kpc . The search covered a broad band of frequencies along with first and second frequency derivatives for a fixed sky position. The search coherently integrated data from the two LIGO interferometers over a time span of 9.2 days using the matched-filtering F -statistic. We found no gravitational-wave signals and set 95% confidence upper limits as stringent as 6.0 ×10-25 on intrinsic strain and 8.5 ×10-6 on fiducial ellipticity. These values beat the indirect limits from energy conservation for stars with characteristic spin-down ages older than 300 years and are within the range of theoretical predictions for possible neutron-star ellipticities. An important feature of this search was use of a barycentric resampling algorithm which substantially reduced computational cost; this method is used extensively in searches of Advanced LIGO and Virgo detector data.

The SAMI Galaxy Survey: can we trust aperture corrections to predict star formation?

NASA Astrophysics Data System (ADS)

Richards, S. N.; Bryant, J. J.; Croom, S. M.; Hopkins, A. M.; Schaefer, A. L.; Bland-Hawthorn, J.; Allen, J. T.; Brough, S.; Cecil, G.; Cortese, L.; Fogarty, L. M. R.; Gunawardhana, M. L. P.; Goodwin, M.; Green, A. W.; Ho, I.-T.; Kewley, L. J.; Konstantopoulos, I. S.; Lawrence, J. S.; Lorente, N. P. F.; Medling, A. M.; Owers, M. S.; Sharp, R.; Sweet, S. M.; Taylor, E. N.

2016-01-01

In the low-redshift Universe (z < 0.3), our view of galaxy evolution is primarily based on fibre optic spectroscopy surveys. Elaborate methods have been developed to address aperture effects when fixed aperture sizes only probe the inner regions for galaxies of ever decreasing redshift or increasing physical size. These aperture corrections rely on assumptions about the physical properties of galaxies. The adequacy of these aperture corrections can be tested with integral-field spectroscopic data. We use integral-field spectra drawn from 1212 galaxies observed as part of the SAMI Galaxy Survey to investigate the validity of two aperture correction methods that attempt to estimate a galaxy's total instantaneous star formation rate. We show that biases arise when assuming that instantaneous star formation is traced by broad-band imaging, and when the aperture correction is built only from spectra of the nuclear region of galaxies. These biases may be significant depending on the selection criteria of a survey sample. Understanding the sensitivities of these aperture corrections is essential for correct handling of systematic errors in galaxy evolution studies.

V-type multicylinder internal combustion engine

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

Tsuboi, M.

1986-05-20

A V-type multicylinder internal combustion engine is described for vehicles comprising front and rear cylinder blocks arrayed in V shape longitudinally of a vehicle body, front and rear cylinder heads fixed on each cylinder block, pistons sliding in the cylinder blocks, a crank and transmission case formed uniformly on the cylinder blocks, a crankshaft extending transversely of the vehicle body borne rotatably on both side walls of the crank and transmission case at journals on both sides, the crankshaft being coupled to the pistons at a crank pin through connecting rods and provided with front and rear driving sprockets, frontmore » and rear cam shafts mounted rotatably on the cylinder heads with driven sprockets fixed thereon, a front timing chain laid between the front driving sprocket and the front driven sprocket and constituting together with the front driving and driven sprockets a front cam driving means, a rear timing chain laid between the rear driving sprocket and the rear driven sprocket and constituting together with the rear driving and driven sprockets a rear cam driving means, and a speed change gear coupled to the crankshaft by way of a primary reduction gear and a clutch.« less

Intact skull chronic windows for mesoscopic wide-field imaging in awake mice

PubMed Central

Silasi, Gergely; Xiao, Dongsheng; Vanni, Matthieu P.; Chen, Andrew C. N.; Murphy, Timothy H.

2016-01-01

Background Craniotomy-based window implants are commonly used for microscopic imaging, in head-fixed rodents, however their field of view is typically small and incompatible with mesoscopic functional mapping of cortex. New Method We describe a reproducible and simple procedure for chronic through-bone wide-field imaging in awake head-fixed mice providing stable optical access for chronic imaging over large areas of the cortex for months. Results The preparation is produced by applying clear-drying dental cement to the intact mouse skull, followed by a glass coverslip to create a partially transparent imaging surface. Surgery time takes about 30 minutes. A single set-screw provides a stable means of attachment for mesoscale assessment without obscuring the cortical field of view. Comparison with Existing Methods We demonstrate the utility of this method by showing seed-pixel functional connectivity maps generated from spontaneous cortical activity of GCAMP6 signals in both awake and anesthetized mice. Conclusions We propose that the intact skull preparation described here may be used for most longitudinal studies that do not require micron scale resolution and where cortical neural or vascular signals are recorded with intrinsic sensors. PMID:27102043

Biodegradable implants for Pipkin fractures.

PubMed

Prokop, Axel; Helling, Hanns-Joachim; Hahn, Ulrich; Udomkaewkanjana, Chira; Rehm, Klaus Emil

2005-03-01

The current study was designed to clarify whether biodegradable poly-L/DL lactide pins provide an operative alternative for fixation of Pipkin fractures. Nine patients with Pipkin fractures (one with Pipkin Type I, one with Pipkin Type II, and seven with Pipkin Type IV fractures) were treated surgically between 1996 and 2002. In all patients, the femoral head fractures were fixed with biodegradable, 2.7-mm and 2.0-mm polylactide pins. Eight patients were followed up for an average of 54.2 months. One patient died before the final followup. Eight fractures healed uneventfully. In one patient, a persisting femoral head defect led to posttraumatic arthritis requiring insertion of a femoral endoprosthesis at 1 year. The average range of motion of the affected hips of all patients at followup was 109 degrees -0 degrees -0 degrees in flexion and extension. External and internal rotation averaged 37 degrees -0 degrees -29 degrees . One patient had Brooker Grade I heterotopic ossification develop, and another had a Grade II heterotopic develop. Merle d'Aubigne and Postel ratings showed two excellent and five satisfactory results (average score, 13.1). Adverse effects from the polylactide implants were not observed. Pipkin fractures can be fixed successfully with biodegradable polylactide pins.

A combinaison of UV curing technology with ATL process

NASA Astrophysics Data System (ADS)

Balbzioui, I.; Hasiaoui, B.; Barbier, G.; L'hostis, G.; Laurent, F.; Ibrahim, A.; Durand, B.

2017-10-01

In order to reduce the time and the cost of manufacturing composite, UV curing technology combined with automated tape placement process (ATL) based on reverse approach by working with a fixed head was studied in this article. First, a brief description of the developed head placement is presented. Mechanical properties are then evaluated by varying process parameters, including compaction force and tape placement speed. Finally, a parametric study is carried out to identify suitable materials and process parameters to manufacture a photo composite material with high mechanical performances. The obtained results show that UV curing is a very good alternative for thermal polymerization because of its fast cure speed due to less dependency on temperature.

Laser cutting apparatus for nuclear core fuel subassembly

DOEpatents

Walch, Allan P.; Caruolo, Antonio B.

1982-02-23

The object of the invention is to provide a system and apparatus which employs laser cutting to disassemble a nuclear core fuel subassembly. The apparatus includes a gantry frame (C) which straddles the core fuel subassembly (14), an x-carriage (22) travelling longitudinally above the frame which carries a focus head assembly (D) having a vertically moving carriage (46) and a laterally moving carriage (52), a system of laser beam transferring and focusing mirrors carried by the x-carriage and focusing head assembly, and a shroud follower (F) and longitudinal follower (G) for following the shape of shroud (14) to maintain a beam focal point (44) fixed upon the shroud surface for accurate cutting.

Calculating ground water transit time of horizontal flow through leaky aquifers.

PubMed

Braunsfurth, Angelika C; Schneider, Wilfried

2008-01-01

The calculation of ground water transit times is one important factor in ground water protection. In this paper, we present an analytical solution for the transit time for a Dupuit-type flow system applicable to saturated flow through a horizontal leaky aquifer discharging to a downgradient fixed-head boundary under steady-state conditions. We investigate the influence of leakage when comparing the resulting travel times of our model based on head-dependent leakage with the commonly used model with no leakage and a simplified model with constant leakage. The results show significant differences in the position of the water divide and transit time, suggesting that leakage cannot be ignored.

Biphasic modulation of neuro- and interrenal steroidogenesis in juvenile African sharptooth catfish (Clarias gariepinus) exposed to waterborne di-(2-ethylhexyl) phthalate.

PubMed

Arukwe, Augustine; Ibor, Oju R; Adeogun, Aina O

2017-12-01

Receptor (i.e. genomic) and non-receptor (or non-genomic) effects of endocrine toxicology have received limited or almost non-existent attention for tropical species and regions. In the present study, we have evaluated the effects of di-(2-ethylhexyl) phthalate (DEHP) on neuro- and interrenal steroidogenesis of the African catfish (Clarias gariepinus) using molecular, immunochemical and physiological approaches. Juvenile fish (mean weight and length: 5.6±0.6g and 8.2±1.2cm, respectively), were randomly distributed into ten 120L rectangular glass tanks containing 60L of dechlorinated tap water, at 50 fish per exposure group. The fish were exposed to environmentally relevant concentrations of DEHP, consisting of 0 (ethanol solvent control), 10, 100, 200, and 400μg DEHP/L water and performed in two replicates. Brain, liver and head kidney samples were collected at day 3, 7 and 14 after exposure, and analysed for star, p450scc, cyp19a1, cyp17, cyp11β-, 3β-, 17β- and 20β-hsd, and 17β-ohase mRNA expression using real-time PCR. The StAR, P450scc and CYP19 proteins were measured using immunoblotting method, while estradiol-17β (E2) and testosterone (T) were measured in liver homogenate using enzyme immunoassay (EIA). Our data showed a consistent and unique pattern of biphasic effect on star and steroidogenic enzyme genes with increases at low concentration (10μg/L) and thereafter, a concentration-dependent decrease in both the brain and head kidney, that paralleled the expression of StAR, P450scc and CYP19 proteins. Cellular E2 and T levels showed an apparent DEHP concentration-dependent increase at day 14 of exposure. The observed consistency in the current findings and in view of previous reports on contaminants-induced alterations in neuro- and interrenal steroidogenesis, the broader toxicological and endocrine disruptor implication of our data indicate potentials for overt reproductive, metabolic, physiological and general health consequences for the exposed organisms. Copyright © 2017 Elsevier Inc. All rights reserved.

Suzaku Observations of the HMXB 1A 1118-61

NASA Technical Reports Server (NTRS)

Suchy, Slawomir; Pottschmidt, Katja; Rothschild, Richard E.; Wilms, Joern; Fuerst, Felis; Barragan, Laura; Caballero, Isabel; Grinberg, Victoria; Kreykenbohm, Ingo; Doroshenko, Victor;

An Independent Confirmation of the Future Flyby of Gliese 710 to the Solar System Using Gaia DR2

NASA Astrophysics Data System (ADS)

de la Fuente Marcos, Raúl; de la Fuente Marcos, Carlos

2018-05-01

Gliese 710 is a K7V star located 19 pc from the Sun in the constellation of Serpens Cauda, which is headed straight for the solar system. Berski & Dybczynski (2016) used data from Gaia DR1 to show that this star will be 13366 AU from the Sun in 1.35 Myr from now. Here, we present an independent confirmation of this remarkable result using Gaia DR2. Our approach is first validated using as test case that of the closest known stellar flyby, by the binary WISE J072003.20-084651.2 or Scholz's star. Our results confirm, within errors, those in Berski & Dybczynski (2016), but suggest a somewhat closer, both in terms of distance and time, flyby of Gliese 710 to the solar system. Such an interaction might not significantly affect the region inside 40 au as the gravitational coupling among the known planets against external perturbation can absorb efficiently such a perturbation, but it may trigger a major comet shower that will affect the inner solar system.

The Star Wars Scroll Illusion.

PubMed

Shapiro, Arthur G

2015-10-01

The Star Wars Scroll Illusion is a dynamic version of the Leaning Tower Illusion. When two copies of a Star-Wars-like scrolling text are placed side by side (with separate vanishing points), the two scrolls appear to head in different directions even though they are physically parallel in the picture plane. Variations of the illusion are shown with one vanishing point, as well as from an inverted perspective where the scrolls appear to originate in the distance. The demos highlight the conflict between the physical lines in the picture plane and perspective interpretation: With two perspective points, the scrolling texts are parallel to each other in the picture plane but not in perspective interpretation; with one perspective point, the texts are not parallel to each other in the picture plane but are parallel to each other in perspective interpretation. The size of the effect is linearly related to the angle of rotation of the scrolls into the third dimension; the Scroll Illusion is stronger than the Leaning Tower Illusion for rotation angles between 35° and 90°. There is no effect of motion per se on the strength of the illusion.

The Solar and Heliospheric Observatory (SOHO) Mission: An Overview of Flight Dynamics Support of the Early Mission Phase

NASA Technical Reports Server (NTRS)

Short, R.; Behuncik, J.

1996-01-01

The SOHO spacecraft was successfully launched by an Atlas 2AS from the Eastern Range on December 2, 1995. After a short time in a nearly circular parking orbit, the spacecraft was placed by the Centaur upper stage on a transfer trajectory to the L1 libration point where it was inserted into a class 1 Halo orbit. The nominal mission lifetime is two years which will be spent collecting data from the Sun using a complement of twelve instruments. An overview of the early phases of Flight Dynamics Facility support of the mission is given. Maneuvers required for the mission are discussed, and an evaluation of these maneuvers is given with the attendent effects on the resultant orbit. Thruster performance is presented as well as real time monitoring of thruster activity during maneuvers. Attitude areas presented are the star identification process and role angle determination, momentum management, operating constraints on the star tracker, and guide star switching. A brief description of the two Heads Up displays is given.

Ignition transient analysis of solid rocket motor

NASA Technical Reports Server (NTRS)

Han, Samuel S.

1990-01-01

To predict pressure-time and thrust-time behavior of solid rocket motors, a one-dimensional numerical model is developed. The ignition phase of solid rocket motors (time less than 0.4 sec) depends critically on complex interactions among many elements, such as rocket geometry, heat and mass transfer, flow development, and chemical reactions. The present model solves the mass, momentum, and energy equations governing the transfer processes in the rocket chamber as well as the attached converging-diverging nozzle. A qualitative agreement with the SRM test data in terms of head-end pressure gradient and the total thrust build-up is obtained. Numerical results show that the burning rate in the star-segmented head-end section and the erosive burning are two important parameters in the ignition transient of the solid rocket motor (SRM).

Correlative analysis of head kinematics and brain's tissue response: a computational approach toward understanding the mechanisms of blast TBI

NASA Astrophysics Data System (ADS)

Sarvghad-Moghaddam, H.; Rezaei, A.; Ziejewski, M.; Karami, G.

2017-11-01

Upon impingement of blast waves on the head, stress waves generated at the interface of the skull are transferred into the cranium and the brain tissue and may cause mild to severe blast traumatic brain injury. The intensity of the shock front, defined by the blast overpressure (BoP), that is, the blast-induced peak static overpressure, significantly affects head kinematics as well as the tissue responses of the brain. While evaluation of global linear and rotational accelerations may be feasible, an experimental determination of dynamic responses of the brain in terms of intracranial pressure (ICP), maximum shear stress (MSS), and maximum principal strain (MPS) is almost impossible. The main objective of this study is to investigate possible correlations between head accelerations and the brain's ICP, MSS, and MPS. To this end, three different blasts were simulated by modeling the detonation of 70, 200, and 500 g of TNT at a fixed distance from the head, corresponding to peak BoPs of 0.52, 1.2, and 2 MPa, respectively. A nonlinear multi-material finite element algorithm was implemented in the LS-DYNA explicit solver. Fluid-solid interaction between the blast waves and head was modeled using a penalty-based method. Strong correlations were found between the brain's dynamic responses and both global linear and rotational accelerations at different blast intensities (R^{2 }≥98%), implying that global kinematic parameters of the head might be strong predictors of brain tissue biomechanical parameters.

Directional abnormalities of vestibular and optokinetic responses in cerebellar disease

NASA Technical Reports Server (NTRS)

Walker, M. F.; Zee, D. S.; Shelhamer, M. J. (Principal Investigator)

1999-01-01

Directional abnormalities of vestibular and optokinetic responses in patients with cerebellar degeneration are reported. Three-axis magnetic search-coil recordings of the eye and head were performed in eight cerebellar patients. Among these patients, examples of directional cross-coupling were found during (1) high-frequency, high-acceleration head thrusts; (2) constant-velocity chair rotations with the head fixed; (3) constant-velocity optokinetic stimulation; and (4) following repetitive head shaking. Cross-coupling during horizontal head thrusts consisted of an inappropriate upward eye-velocity component. In some patients, sustained constant-velocity yaw-axis chair rotations produced a mixed horizontal-torsional nystagmus and/or an increase in the baseline vertical slow-phase velocity. Following horizontal head shaking, some patients showed an increase in the slow-phase velocity of their downbeat nystagmus. These various forms of cross-coupling did not necessarily occur to the same degree in a given patient; this suggests that different mechanisms may be responsible. It is suggested that cross-coupling during head thrusts may reflect a loss of calibration of brainstem connections involved in the direct vestibular pathways, perhaps due to dysfunction of the flocculus. Cross-coupling during constant-velocity rotations and following head shaking may result from a misorientation of the angular eye-velocity vector in the velocity-storage system. Finally, responses to horizontal optokinetic stimulation included an inappropriate torsional component in some patients. This suggests that the underlying organization of horizontal optokinetic tracking is in labyrinthine coordinates. The findings are also consistent with prior animal-lesion studies that have shown a role for the vestibulocerebellum in the control of the direction of the VOR.

Aviation spatial orientation in relationship to head position, altitude interpretation, and control.

PubMed

Smith, D R; Cacioppo, A J; Hinman, G E

1997-06-01

Recently, a visually driven neck reflex was identified as causing head tilt toward the horizon during VMC flight. If this is the case, then pilots orient about a fixed rather than moving horizon, implying current attitude instruments inaccurately present spatial information. The purpose of this study was to determine if the opto-kinetic cervical neck reflex has an effect dependent on passive (autopilot) or active control of the aircraft. Further, findings could help determine if the opto-kinetic cervical reflex is characteristic of other flight crewmembers. There were 16 military pilots who flew two 13-min VMC low-level routes in a large dome flight simulator. Head position in relation to aircraft bank angle was recorded by a head tracker device. During one low-level route, the pilot had a supervisory role as the autopilot flew the aircraft (passive). The other route was flow manually by the pilot (active). Pilots consistently tilted the head to maintain alignment with the horizon. Similar head tilt angles were found in both the active and passive flight phases. However, head tilt had a faster onset rate in the passive condition. Results indicate the opto-kinetic cervical reflex affects pilots while actively flying or in a supervisory role as the autopilot flies. The consistent head tilt angles in both conditions should be considered in attitude indicator, HUD, and HMD designs. Further, results seem to indicate that non-pilot flight crewmembers are affected by the opto-kinetic cervical reflex which should be considered in spatial disorientation and airsickness discussions.

Efficacy of 3 toothbrush treatments on plaque removal in orthodontic patients assessed with digital plaque imaging: a randomized controlled trial.

PubMed

Erbe, Christina; Klukowska, Malgorzata; Tsaknaki, Iris; Timm, Hans; Grender, Julie; Wehrbein, Heinrich

2013-06-01

Good oral hygiene is a challenge for orthodontic patients because food readily becomes trapped around the brackets and under the archwires, and appliances are an obstruction to mechanical brushing. The purpose of this study was to compare plaque removal efficacy of 3 toothbrush treatments in orthodontic subjects. This was a replicate-use, single-brushing, 3-treatment, examiner-blind, randomized, 6-period crossover study with washout periods of approximately 24 hours between visits. Forty-six adolescent and young adult patients with fixed orthodontics from a university clinic in Germany were randomized, based on computer-generated randomization, to 1 of 3 treatments: (1) oscillating-rotating electric toothbrush with a specially designed orthodontic brush head (Oral-B Triumph, OD17; Procter & Gamble, Cincinnati, Ohio); (2) the same electric toothbrush handle with a regular brush head (EB25; Procter & Gamble); and (3) a regular manual toothbrush (American Dental Association, Chicago, Ill). The primary outcome was the plaque score change from baseline, which we determined using digital plaque image analysis. Forty-five subjects completed the study. The differences in mean plaque removal (95% confidence interval) between the electric toothbrush with an orthodontic brush head (6% [4.4%-7.6%]) or a regular brush head (3.8% [2.2%-5.3%]) and the manual toothbrush were significant (P <0.001). Plaque removal with the electric toothbrush with the orthodontic brush head was superior (2.2%; P = 0.007) to the regular brush head. No adverse events were seen. The electric toothbrush, with either brush head, demonstrated significantly greater plaque removal over the manual brush. The orthodontic brush head was superior to the regular head. Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Nintendo Wii remote controllers for head posture measurement: accuracy, validity, and reliability of the infrared optical head tracker.

PubMed

Kim, Jongshin; Nam, Kyoung Won; Jang, Ik Gyu; Yang, Hee Kyung; Kim, Kwang Gi; Hwang, Jeong-Min

2012-03-15

To evaluate the accuracy, validity, and reliability of a newly developed infrared optical head tracker (IOHT) using Nintendo Wii remote controllers (WiiMote; Nintendo Co. Ltd., Kyoto, Japan) for measurement of the angle of head posture. The IOHT consists of two infrared (IR) receivers (WiiMote) that are fixed to a mechanical frame and connected to a monitoring computer via a Bluetooth communication channel and an IR beacon that consists of four IR light-emitting diodes (LEDs). With the use of the Cervical Range of Motion (CROM; Performance Attainment Associates, St. Paul, MN) as a reference, one- and three-dimensional (1- and 3-D) head postures of 20 normal adult subjects (20-37 years of age; 9 women and 11 men) were recorded with the IOHT. In comparison with the data from the CROM, the IOHT-derived results showed high consistency. The measurements of 1- and 3-D positions of the human head with the IOHT were very close to those of the CROM. The correlation coefficients of 1- and 3-D positions between the IOHT and the CROM were more than 0.99 and 0.96 (P < 0.05, Pearson's correlation test), respectively. Reliability tests of the IOHT for the normal adult subjects for 1- and 3-D positions of the human head had 95% limits of agreement angles of approximately ±4.5° and ±8.0°, respectively. The IOHT showed strong concordance with the CROM and relatively good test-retest reliability, thus proving its validity and reliability as a head-posture-measuring device. Considering its high performance, ease of use, and low cost, the IOHT has the potential to be widely used as a head-posture-measuring device in clinical practice.

Clumpy wind accretion in supergiant neutron star high mass X-ray binaries

NASA Astrophysics Data System (ADS)

Bozzo, E.; Oskinova, L.; Feldmeier, A.; Falanga, M.

2016-05-01

The accretion of the stellar wind material by a compact object represents the main mechanism powering the X-ray emission in classical supergiant high mass X-ray binaries and supergiant fast X-ray transients. In this work we present the first attempt to simulate the accretion process of a fast and dense massive star wind onto a neutron star, taking into account the effects of the centrifugal and magnetic inhibition of accretion ("gating") due to the spin and magnetic field of the compact object. We made use of a radiative hydrodynamical code to model the nonstationary radiatively driven wind of an O-B supergiant star and then place a neutron star characterized by a fixed magnetic field and spin period at a certain distance from the massive companion. Our calculations follow, as a function of time (on a total timescale of several hours), the transitions of the system through all different accretion regimes that are triggered by the intrinsic variations in the density and velocity of the nonstationary wind. The X-ray luminosity released by the system is computed at each time step by taking into account the relevant physical processes occurring in the different accretion regimes. Synthetic lightcurves are derived and qualitatively compared with those observed from classical supergiant high mass X-ray binaries and supergiant fast X-ray transients. Although a number of simplifications are assumed in these calculations, we show that taking into account the effects of the centrifugal and magnetic inhibition of accretion significantly reduces the average X-ray luminosity expected for any neutron star wind-fed binary. The present model calculations suggest that long spin periods and stronger magnetic fields are favored in order to reproduce the peculiar behavior of supergiant fast X-ray transients in the X-ray domain.

Astronomical Characteristics of Cheonsang-yeolcha-bunyajido from the Perspective of Manufacturing Methods

NASA Astrophysics Data System (ADS)

Ahn, Sang-Hyeon

2015-03-01

I investigated a method for drawing the star chart in the planisphere Cheonsang-yeolcha-bunyajido. The outline of the star chart can be constructed by considering the astronomical information given in the planisphere alone and the drawing method described in Xin-Tangshu; further the chart can be completed by using additional information on the shape and linking method of asterisms out of an inherited star chart. The circles of perpetual visibility, the equator, and the circle of perpetual invisibility are concentric, and their common center locates the Tianshu-xing, which was defined to be a pole star in the Han dynasty. The radius of the circle of perpetual visibility was modified in accordance with the latitude of Seoul, whereas the other circles were drawn for the latitude of 35°, which had been the reference latitude in ancient Chinese astronomy. The ecliptic was drawn as an exact circle by parallel transference of the equator circle to fix the location of the equinoxes at the positions recorded in the epitaph of the planisphere. The positions of equinoxes originated from the Han dynasty. The 365 ticks around the boundary of the circle of perpetual invisibility were possibly drawn by segmenting the circumference with an arc length instead of a chord length with the ratio of the circumference of a circle to its diameter as accurate as 3.14 presumed. The 12 equatorial sectors were drawn on the boundary of the star-chart in accordance with the beginning and ending lodge angles given in the epitaph that originated from the Han dynasty. The determinative lines for the 28 lunar lodges were drawn to intersect their determinative stars, but seven determinative stars are deviated. According to the treatises of the Tang dynasty, these anomalies were inherited from charts of the period earlier than the Tang dynasty. Thus, the star chart in Cheonsang-yeolcha-bunyajido preserves the old tradition that had existed before the present Chinese tradition reformed in approximately 700 CE. In conclusion, the star chart in Cheonsang-yeolcha-bunyajido shows the sky of the former Han dynasty with the equator modified to the latitude of Seoul.

THE FOURTH US NAVAL OBSERVATORY CCD ASTROGRAPH CATALOG (UCAC4)

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

Zacharias, N.; Finch, C. T.; Bartlett, J. L.

2013-02-01

The fourth United States Naval Observatory (USNO) CCD Astrograph Catalog, UCAC4, was released in 2012 August (double-sided DVD and CDS data center Vizier catalog I/322). It is the final release in this series and contains over 113 million objects; over 105 million of them with proper motions (PMs). UCAC4 is an updated version of UCAC3 with about the same number of stars also covering all-sky. Bugs were fixed, Schmidt plate survey data were avoided, and precise five-band photometry was added for about half the stars. Astrograph observations have been supplemented for bright stars by FK6, Hipparcos, and Tycho-2 data tomore » compile a UCAC4 star catalog complete from the brightest stars to about magnitude R = 16. Epoch 1998-2004 positions are obtained from observations with the 20 cm aperture USNO Astrograph's 'red lens', equipped with a 4k by 4k CCD. Mean positions and PMs are derived by combining these observations with over 140 ground- and space-based catalogs, including Hipparcos/Tycho and the AC2000.2, as well as unpublished measures of over 5000 plates from other astrographs. For most of the faint stars in the southern hemisphere, the first epoch plates from the Southern Proper Motion program form the basis for PMs, while the Northern Proper Motion first epoch plates serve the same purpose for the rest of the sky. These data are supplemented by 2MASS near-IR photometry for about 110 million stars and five-band (B, V, g, r, i) APASS data for over 51 million stars. Thus the published UCAC4, as were UCAC3 and UCAC2, is a compiled catalog with the UCAC observational program being a major component. The positional accuracy of stars in UCAC4 at mean epoch is about 15-100 mas per coordinate, depending on magnitude, while the formal errors in PMs range from about 1 to 10 mas yr{sup -1} depending on magnitude and observing history. Systematic errors in PMs are estimated to be about 1-4 mas yr{sup -1}.« less

Chemical composition of the metal-poor carbon star HD 187216.

NASA Astrophysics Data System (ADS)

Kipper, T.; Jorgensen, U. G.

1994-10-01

We have derived C, N and metal abundances for the metal-deficient late-type (C3,3CH) CH giant HD 187216 (α_2000.0_=19h24m18.6s, δ_2000.0_=+85deg21'56.5"). The oxygen abundance was fixed at logA(O)=7.0, assuming that it follows the trend of oxygen overabundance relative to iron found in halo stars in general. New model atmospheres of metal-poor carbon stars were calculated with continuum opacity sources and molecular lines of CO, CN, C_2_, HCN, C_2_H_2_ and C_3_. Numerical experiments with various assumed input parameters, such as effective temperature, T_eff_, surface gravity, logg, microturbulent velocity, ξ_t_, and dissociation energy of the CN molecule, D_0_(CN), were performed when constructing the model atmospheres and calculating the synthetic spectra. The atmospheric model with T_eff_=3500K, logg=0.4, ξ_t_=3km/s, ^12^C/^13^C=8 and D_0_(CN)=7.9eV was adopted for abundance analysis. The star was found to be extremely metal-deficient, [Fe/H]=-2.48. The carbon abundance is logA(C)=7.33, the nitrogen abundance is logA(N)=5.60 corresponding to [C/Fe]=+1.3, [N/Fe]=+0.2, and [N/C]=-1.1. The carbon isotopic abundance ratio is ^12^C/^13^C=7.0. The abundances of heavy elements produced in the s-process are larger than in early-type CH stars. The ratio of overabundance of heavier s-process elements to that of lighter ones, [hs/ls]=1.0, points to a very high neutron exposure in a single irradiation event. Search for binarity of HD 187216 has failed, and the star can be an intrinsic asymptotic giant branch (AGB) carbon star with some similarities to the C stars in the dwarf galaxies. If the CH characteristics are due to mass transfer it is most likely oxygen-rich material that has been donated. The star possesses both a low nitrogen abundance and a low ^12^C/^13^C ratio, in conflict with the standard stellar evolution theory.

Nuclear constraints on the age of the universe

NASA Technical Reports Server (NTRS)

Schramm, D. N.

1983-01-01

A review is made of how one can use nuclear physics to put rather stringent limits on the age of the universe and thus the cosmic distance scale. The age can be estimated to a fair degree of accuracy. No single measurement of the time since the Big Bang gives a specific, unambiguous age. There are several methods that together fix the age with surprising precision. In particular, there are three totally independent techniques for estimating an age and a fourth technique which involves finding consistency of the other three in the framework of the standard Big Bang cosmological model. The three independent methods are: cosmological dynamics, the age of the oldest stars, and radioactive dating. This paper concentrates on the third of the three methods, and the consistency technique. Previously announced in STAR as N83-34868

Chandra X-ray Grating Spectrometry of Eta Carinae near X-ray Minimum: I. Variability of the Sulfur and Silicon Emission Lines

NASA Technical Reports Server (NTRS)

Henley, D. B.; Corcoran, M. F.; Pittard, J. M.; Stevens, I. R.; Hamaguchi, K.; Gull, T. R.

2008-01-01

We report on variations in important X-ray emission lines in a series of Chandra grating spectra of the supermassive colliding wind binary star eta Car, including key phases around the X-ray minimum/periastron passage in 2003.5. The X-rays arise from the collision of the slow, dense wind of eta Car with the fast, low-density wind of an otherwise hidden companion star. The X-ray emission lines provide the only direct measure of the flow dynamics of the companion's wind along the wind-wind collision zone. We concentrate here on the silicon and sulfur lines, which are the strongest and best resolved lines in the X-ray spectra. Most of the line profiles can be adequately fit with symmetric Gaussians with little significant skewness. Both the silicon and sulfur lines show significant velocity shifts and correlated increases in line widths through the observations. The R = forbidden-to-intercombination ratio from the Si XIII and S XV triplets is near or above the low-density limit in all observations, suggesting that the line-forming region is > 1.6 stellar radii from the companion star, and that the emitting plasma may be in a non-equilibrium state. We show that simple geometrical models cannot simultaneously fit both the observed centroid variations and changes in line width as a function of phase. We show that the observed profiles can be fitted with synthetic profiles with a reasonable model of the emissivity along the wind-wind collision boundary. We use this analysis to help constrain the line formation region as a function of orbital phase, and the orbital geometry. Subject headings: X-rays: stars -stars: early-type-stars: individual (q Car)

Colliding black holes and pulsating compact objects

NASA Astrophysics Data System (ADS)

Andrade, Zeferino

2000-08-01

This thesis presents a study of two kinds of sources of gravitational waves: black hole collisions and pulsating compact objects (either a black hole or a star) The computational solution of the Einstein field equations for the coalescence of two black holes is of great interest for both theoretical and astrophysical reasons. Despite the strong motivation for results, outstanding mathematical and numerical problems have prevented a complete analysis of two black hole systems. Workers in the field have resorted to approximate techniques that make the study of such systems tractable. In Chapter 2 we use the close limit approximation to compute the gravitational energy radiated, and the recoil velocity acquired, by a system of two unequal mass black holes colliding head-on. A recent independent comparison of our approximate result with a full numerical analysis of the problem shows excellent agreement. Until recently, vibrations even of relativistically compact stars were studied using Newtonian physics and the weak field limit of general relativity. The study of the problem in the framework of general relativity revealed the existence of modes of vibration (w modes) characteristic of the spacetime geometry and therefore modes not predicted by Newtonian physics. Chapter 3 addresses the question of whether these modes can be excited in a natural astrophysical process. A small particle with a given energy and angular momentum is scattered by a compact star or black hole and in the process excites, although weakly, the w modes. Chapter 4 compares the study of pulsating stars in a Newtonian framework and in a fully relativistic setting. To excite the vibrations of the stellar model we use time dependent surface mass density and surface stress in a thin spherical shell surrounding the star. Even for stars as compact as typical neutron stars (radius ~ 5G/ c2 × mass), the two theories predict essentially the same level of excitation of the f (fluid) modes of the star. The w modes are not excited for these stars. All of the chapters in this thesis, except the introductory chapter, have been published or have been submitted for publication.

BY POPULAR DEMAND: HUBBLE OBSERVES THE HORSEHEAD NEBULA

NASA Technical Reports Server (NTRS)

2002-01-01

Rising from a sea of dust and gas like a giant seahorse, the Horsehead nebula is one of the most photographed objects in the sky. NASA's Hubble Space Telescope took a close-up look at this heavenly icon, revealing the cloud's intricate structure. This detailed view of the horse's head is being released to celebrate the orbiting observatory's eleventh anniversary. Produced by the Hubble Heritage Project, this picture is a testament to the Horsehead's popularity. Internet voters selected this object for the orbiting telescope to view. The Horsehead, also known as Barnard 33, is a cold, dark cloud of gas and dust, silhouetted against the bright nebula, IC 434. The bright area at the top left edge is a young star still embedded in its nursery of gas and dust. But radiation from this hot star is eroding the stellar nursery. The top of the nebula also is being sculpted by radiation from a massive star located out of Hubble's field of view. Only by chance does the nebula roughly resemble the head of a horse. Its unusual shape was first discovered on a photographic plate in the late 1800s. Located in the constellation Orion, the Horsehead is a cousin of the famous pillars of dust and gas known as the Eagle nebula. Both tower-like nebulas are cocoons of young stars. The Horsehead nebula lies just south of the bright star Zeta Orionis, which is easily visible to the unaided eye as the left-hand star in the line of three that form Orion's Belt. Amateur astronomers often use the Horsehead as a test of their observing skills; it is known as one of the more difficult objects to see visually in an amateur-sized telescope. The magnificent extent of the Horsehead is best appreciated in a new wide-field image of the nebula being released today by the National Optical Astronomy Observatory, taken by Travis Rector with the National Science Foundation's 0.9 meter telescope at Kitt Peak National Observatory near Tucson, AZ. This popular celestial target was the clear winner among more than 5,000 Internet voters, who were asked last year to select an astronomical target for the Hubble telescope to observe. The voters included students, teachers, and professional and amateur astronomers. This 11th anniversary release image was composed by the Hubble Heritage Team, which superimposed Hubble data onto ground-based data (limited to small triangular regions around the outer edge of the image). Ground-based image courtesy of Nigel A. Sharp (NOAO/AURA/NSF) taken at the 0.9-meter telescope on Kitt Peak. Image Credit: NASA, NOAO, ESA and The Hubble Heritage Team (STScI/AURA) Acknowledgment: K. Noll (Hubble Heritage PI/STScI), C. Luginbuhl (USNO), F. Hamilton (Hubble Heritage/STScI)

Air-Track: a real-world floating environment for active sensing in head-fixed mice.

PubMed

Nashaat, Mostafa A; Oraby, Hatem; Sachdev, Robert N S; Winter, York; Larkum, Matthew E

2016-10-01

Natural behavior occurs in multiple sensory and motor modalities and in particular is dependent on sensory feedback that constantly adjusts behavior. To investigate the underlying neuronal correlates of natural behavior, it is useful to have access to state-of-the-art recording equipment (e.g., 2-photon imaging, patch recordings, etc.) that frequently requires head fixation. This limitation has been addressed with various approaches such as virtual reality/air ball or treadmill systems. However, achieving multimodal realistic behavior in these systems can be challenging. These systems are often also complex and expensive to implement. Here we present "Air-Track," an easy-to-build head-fixed behavioral environment that requires only minimal computational processing. The Air-Track is a lightweight physical maze floating on an air table that has all the properties of the "real" world, including multiple sensory modalities tightly coupled to motor actions. To test this system, we trained mice in Go/No-Go and two-alternative forced choice tasks in a plus maze. Mice chose lanes and discriminated apertures or textures by moving the Air-Track back and forth and rotating it around themselves. Mice rapidly adapted to moving the track and used visual, auditory, and tactile cues to guide them in performing the tasks. A custom-controlled camera system monitored animal location and generated data that could be used to calculate reaction times in the visual and somatosensory discrimination tasks. We conclude that the Air-Track system is ideal for eliciting natural behavior in concert with virtually any system for monitoring or manipulating brain activity. Copyright © 2016 the American Physiological Society.

Air-Track: a real-world floating environment for active sensing in head-fixed mice

PubMed Central

Oraby, Hatem; Sachdev, Robert N. S.; Winter, York

2016-01-01

Natural behavior occurs in multiple sensory and motor modalities and in particular is dependent on sensory feedback that constantly adjusts behavior. To investigate the underlying neuronal correlates of natural behavior, it is useful to have access to state-of-the-art recording equipment (e.g., 2-photon imaging, patch recordings, etc.) that frequently requires head fixation. This limitation has been addressed with various approaches such as virtual reality/air ball or treadmill systems. However, achieving multimodal realistic behavior in these systems can be challenging. These systems are often also complex and expensive to implement. Here we present “Air-Track,” an easy-to-build head-fixed behavioral environment that requires only minimal computational processing. The Air-Track is a lightweight physical maze floating on an air table that has all the properties of the “real” world, including multiple sensory modalities tightly coupled to motor actions. To test this system, we trained mice in Go/No-Go and two-alternative forced choice tasks in a plus maze. Mice chose lanes and discriminated apertures or textures by moving the Air-Track back and forth and rotating it around themselves. Mice rapidly adapted to moving the track and used visual, auditory, and tactile cues to guide them in performing the tasks. A custom-controlled camera system monitored animal location and generated data that could be used to calculate reaction times in the visual and somatosensory discrimination tasks. We conclude that the Air-Track system is ideal for eliciting natural behavior in concert with virtually any system for monitoring or manipulating brain activity. PMID:27486102

Experimental verification of high energy laser-generated impulse for remote laser control of space debris.

PubMed

Lorbeer, Raoul-Amadeus; Zwilich, Michael; Zabic, Miroslav; Scharring, Stefan; Eisert, Lukas; Wilken, Jascha; Schumacher, Dennis; Roth, Markus; Eckel, Hans-Albert

2018-05-31

Walking along a beach one may notice debris being washed ashore from the vast oceans. Then, turning your head up at night you even might noticed a shooting star or a bright spot passing by. Chances are, that you witnessed space debris, endangering future space flight in lower earth orbit. If it was possible to turn cm-sized debris into shooting stars the problem might be averted. Unfortunately, these fragments counting in the 100 thousands are not controllable. To possibly regain control we demonstrate how to exert forces on a free falling debris object from a distance by ablating material with a high energy ns-laser-system. Thrust effects did scale as expected from simulations and led to speed gains above 0.3 m/s per laser pulse in an evacuated micro-gravity environment.

Exp. 55-56 GCTC News Conference, Red Square and Museum Visit

NASA Image and Video Library

2018-02-26

Expedition 55-56 Crew Conducts Traditional Ceremonies in Star City and Moscow, Russia----- : Expedition 55-56 Soyuz Commander Oleg Artemyev of Roscosmos and Flight Engineers Drew Feustel and Ricky Arnold of NASA, the next crew headed to the International Space Station, visited the Gagarin Museum at the Gagarin Cosmonaut Training Center in Star City, Russia, Feb. 22 where they viewed historic space artifacts, then visited Red Square in Moscow for traditional ceremonies, including the laying of flowers at the Kremlin Wall where Russian space icons are interred. Their backups, Alexey Ovchinin of Roscosmos and Nick Hague of NASA, also participated in the visits. Artemyev, Feustel and Arnold are scheduled to launch on March 21 from the Baikonur Cosmodrome in Kazakhstan in the Soyuz MS-08 spacecraft for a five-month mission on the orbiting laboratory.

Using a smartphone as a tool to measure compensatory and anomalous head positions.

PubMed

Farah, Michelle de Lima; Santinello, Murillo; Carvalho, Luis Eduardo Morato Rebouças de; Uesugui, Carlos Fumiaki; Barcellos, Ronaldo Boaventura

2018-01-01

To describe a new method for measuring anomalous head positions by using a cell phone. The photo rotation feature of the iPhone® PHOTOS application was used. With the patient seated on a chair, a horizontal stripe was fixed on the wall in the background and a sagittal stripe was fixed on the seat. Photographs were obtained in the following views: front view (photographs A and B; with the head tilted over one shoulder) and upper axial view (photographs C and D; viewing the forehead and nose) (A and C are without camera rotation, and B and D are with camera rotation). A blank sheet of paper with two straight lines making a 32-degree angle was also photographed. Thirty examiners were instructed to measure the rotation required to align the reference points with the orthogonal axes. In order to set benchmarks to be compared with the measurements obtained by the examiners, blue lines were digitally added to the front and upper view photographs. In the photograph of the sheet of paper (p=0.380 and a=5%), the observed values did not differ statistically from the known value of 32 degrees. Mean measurements were as follows: front view photograph A, 22.8 ± 2.77; front view B, 21.4 ± 1.61; upper view C, 19.6 ± 2.36; and upper view D, 20.1 ± 2.33 degrees. The mean difference in measurements for the front view photograph A was -1.88 (95% CI -2.88 to -0.88), front view B was -0.37 (95% CI -0.97 to 0.17), upper view C was 1.43 (95% CI 0.55 to 2.24), and upper view D was 1.87 (95% CI 1.02 to 2.77). The method used in this study for measuring anomalous head position is reproducible, with maximum variations for AHPs of 2.88 degrees around the X-axis and 2.77 degrees around the Y-axis.

Head-Mounted and Head-Up Display Glossary

NASA Technical Reports Server (NTRS)

Newman, Richard L.; Allen, J. Edwin W. (Technical Monitor)

1997-01-01

One of the problems in head-up and helmet-mounted display (HMD) literature has been a lack of standardization of words and abbreviations. Several different words have been used for the same concept; for example, flight path angle, flight path marker, velocity vector, and total velocity vector all refer to the same thing. In other cases, the same term has been used with two different meanings, such as binocular field-of-view which means the field-of-view visible to both left and right eyes according to some or the field-of-view visible to either the left or right eye or both according to others. Many of the terms used in HMD studies have not been well-defined. We need to have a common language to ensure that system descriptions are communicated. As an example, the term 'stabilized' has been widely used with two meanings. 'Roll-stabilized' has been used to mean a symbol which rotates to indicate the roll or bank of the aircraft. 'World-stabilized' and 'head-stabilized' have both been used to indicate symbols which move to remain fixed with respect to external objects. HMDs present unique symbology problems not found in HUDs. Foremost among these is the issue of maintaining spatial orientation of the symbols. All previous flight displays, round dial instruments, HDDs, and HUDs have been fixed in the cockpit. With the HMD, the flight display can move through a large angle. The coordinates use in transforming from the real-world to the aircraft to the HMD have not been consistently defined. This glossary contains terms relating to optics and vision, displays, and flight information, weapons and aircraft systems. Some definitions, such as Navigation Display, have been added to clarify the definitions for Primary Flight Display and Primary Flight Reference. A list of HUD/HMD related abbreviations is also included.

The MOSDEF Survey: A Stellar Mass–SFR–Metallicity Relation Exists at z ∼ 2.3

NASA Astrophysics Data System (ADS)

Sanders, Ryan L.; Shapley, Alice E.; Kriek, Mariska; Freeman, William R.; Reddy, Naveen A.; Siana, Brian; Coil, Alison L.; Mobasher, Bahram; Davé, Romeel; Shivaei, Irene; Azadi, Mojegan; Price, Sedona H.; Leung, Gene; Fetherholf, Tara; de Groot, Laura; Zick, Tom; Fornasini, Francesca M.; Barro, Guillermo

2018-05-01

We investigate the nature of the relation among stellar mass, star formation rate, and gas-phase metallicity (the {M}* –SFR–Z relation) at high redshifts using a sample of 260 star-forming galaxies at z ∼ 2.3 from the MOSDEF survey. We present an analysis of the high-redshift {M}* –SFR–Z relation based on several emission-line ratios for the first time. We show that a {M}* –SFR–Z relation clearly exists at z ∼ 2.3. The strength of this relation is similar to predictions from cosmological hydrodynamical simulations. By performing a direct comparison of stacks of z ∼ 0 and z ∼ 2.3 galaxies, we find that z ∼ 2.3 galaxies have ∼0.1 dex lower metallicity at fixed {M}* and SFR. In the context of chemical evolution models, this evolution of the {M}* –SFR–Z relation suggests an increase with redshift of the mass-loading factor at fixed {M}* , as well as a decrease in the metallicity of infalling gas that is likely due to a lower importance of gas recycling relative to accretion from the intergalactic medium at high redshifts. Performing this analysis simultaneously with multiple metallicity-sensitive line ratios allows us to rule out the evolution in physical conditions (e.g., N/O ratio, ionization parameter, and hardness of the ionizing spectrum) at fixed metallicity as the source of the observed trends with redshift and with SFR at fixed {M}* at z ∼ 2.3. While this study highlights the promise of performing high-order tests of chemical evolution models at high redshifts, detailed quantitative comparisons ultimately await a full understanding of the evolution of metallicity calibrations with redshift. Based on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation.

Surgeon point-of-view recording: Using a high-definition head-mounted video camera in the operating room.

PubMed

Nair, Akshay Gopinathan; Kamal, Saurabh; Dave, Tarjani Vivek; Mishra, Kapil; Reddy, Harsha S; Della Rocca, David; Della Rocca, Robert C; Andron, Aleza; Jain, Vandana

2015-10-01

To study the utility of a commercially available small, portable ultra-high definition (HD) camera (GoPro Hero 4) for intraoperative recording. A head mount was used to fix the camera on the operating surgeon's head. Due care was taken to protect the patient's identity. The recorded video was subsequently edited and used as a teaching tool. This retrospective, noncomparative study was conducted at three tertiary eye care centers. The surgeries recorded were ptosis correction, ectropion correction, dacryocystorhinostomy, angular dermoid excision, enucleation, blepharoplasty and lid tear repair surgery (one each). The recorded videos were reviewed, edited, and checked for clarity, resolution, and reproducibility. The recorded videos were found to be high quality, which allowed for zooming and visualization of the surgical anatomy clearly. Minimal distortion is a drawback that can be effectively addressed during postproduction. The camera, owing to its lightweight and small size, can be mounted on the surgeon's head, thus offering a unique surgeon point-of-view. In our experience, the results were of good quality and reproducible. A head-mounted ultra-HD video recording system is a cheap, high quality, and unobtrusive technique to record surgery and can be a useful teaching tool in external facial and ophthalmic plastic surgery.

Surgeon point-of-view recording: Using a high-definition head-mounted video camera in the operating room

PubMed Central

Nair, Akshay Gopinathan; Kamal, Saurabh; Dave, Tarjani Vivek; Mishra, Kapil; Reddy, Harsha S; Rocca, David Della; Rocca, Robert C Della; Andron, Aleza; Jain, Vandana

2015-01-01

Objective: To study the utility of a commercially available small, portable ultra-high definition (HD) camera (GoPro Hero 4) for intraoperative recording. Methods: A head mount was used to fix the camera on the operating surgeon's head. Due care was taken to protect the patient's identity. The recorded video was subsequently edited and used as a teaching tool. This retrospective, noncomparative study was conducted at three tertiary eye care centers. The surgeries recorded were ptosis correction, ectropion correction, dacryocystorhinostomy, angular dermoid excision, enucleation, blepharoplasty and lid tear repair surgery (one each). The recorded videos were reviewed, edited, and checked for clarity, resolution, and reproducibility. Results: The recorded videos were found to be high quality, which allowed for zooming and visualization of the surgical anatomy clearly. Minimal distortion is a drawback that can be effectively addressed during postproduction. The camera, owing to its lightweight and small size, can be mounted on the surgeon's head, thus offering a unique surgeon point-of-view. In our experience, the results were of good quality and reproducible. Conclusions: A head-mounted ultra-HD video recording system is a cheap, high quality, and unobtrusive technique to record surgery and can be a useful teaching tool in external facial and ophthalmic plastic surgery. PMID:26655001

Contact Analog/Compressed Symbology Heading Tape Assessment

NASA Technical Reports Server (NTRS)

Shively, R. Jay; Atencio, Adolph; Turpin, Terry; Dowell, Susan

2002-01-01

A simulation assessed the performance, handling qualities and workload associated with a contact-analog, world-referenced heading tape as implemented on the Comanche Helmet Integrated Display Sight System (HIDSS) when compared with a screen-fixed, compressed heading tape. Six pilots, four active duty Army Aviators and two civilians flew three ADS-33 maneuvers and a traffic pattern in the Ames Vertical Motion Simulation facility. Small, but statistically significant advantages were found for the compressed symbology for handling qualities, workload, and some of the performance measures. It should be noted however that the level of performance and handling qualities for both symbology sets fell within the acceptable tolerance levels. Both symbology sets yield satisfactory handling qualities and performance in velocity stabilization mode and adequate handling qualities in the automatic flight control mode. Pilot comments about the contact analog symbology highlighted the lack of useful rate of change information in the heading tape and "blurring" due to the rapid movement of the heading tape. These issues warrant further study. Care must be taken in interpreting the operational significance of these results. The symbology sets yielded categorically similar data, i.e., acceptable handling qualities and adequate performance, so while the results point to the need for further study, their operational significance has yet to be determined.

Development of a Hybrid Atomic Force Microscopic Measurement System Combined with White Light Scanning Interferometry

PubMed Central

Guo, Tong; Wang, Siming; Dorantes-Gonzalez, Dante J.; Chen, Jinping; Fu, Xing; Hu, Xiaotang

2012-01-01

A hybrid atomic force microscopic (AFM) measurement system combined with white light scanning interferometry for micro/nanometer dimensional measurement is developed. The system is based on a high precision large-range positioning platform with nanometer accuracy on which a white light scanning interferometric module and an AFM head are built. A compact AFM head is developed using a self-sensing tuning fork probe. The head need no external optical sensors to detect the deflection of the cantilever, which saves room on the head, and it can be directly fixed under an optical microscopic interferometric system. To enhance the system’s dynamic response, the frequency modulation (FM) mode is adopted for the AFM head. The measuring data can be traceable through three laser interferometers in the system. The lateral scanning range can reach 25 mm × 25 mm by using a large-range positioning platform. A hybrid method combining AFM and white light scanning interferometry is proposed to improve the AFM measurement efficiency. In this method, the sample is measured firstly by white light scanning interferometry to get an overall coarse morphology, and then, further measured with higher resolution by AFM. Several measuring experiments on standard samples demonstrate the system’s good measurement performance and feasibility of the hybrid measurement method. PMID:22368463

Development of a hybrid atomic force microscopic measurement system combined with white light scanning interferometry.

PubMed

Guo, Tong; Wang, Siming; Dorantes-Gonzalez, Dante J; Chen, Jinping; Fu, Xing; Hu, Xiaotang

2012-01-01

A hybrid atomic force microscopic (AFM) measurement system combined with white light scanning interferometry for micro/nanometer dimensional measurement is developed. The system is based on a high precision large-range positioning platform with nanometer accuracy on which a white light scanning interferometric module and an AFM head are built. A compact AFM head is developed using a self-sensing tuning fork probe. The head need no external optical sensors to detect the deflection of the cantilever, which saves room on the head, and it can be directly fixed under an optical microscopic interferometric system. To enhance the system's dynamic response, the frequency modulation (FM) mode is adopted for the AFM head. The measuring data can be traceable through three laser interferometers in the system. The lateral scanning range can reach 25 mm × 25 mm by using a large-range positioning platform. A hybrid method combining AFM and white light scanning interferometry is proposed to improve the AFM measurement efficiency. In this method, the sample is measured firstly by white light scanning interferometry to get an overall coarse morphology, and then, further measured with higher resolution by AFM. Several measuring experiments on standard samples demonstrate the system's good measurement performance and feasibility of the hybrid measurement method.

Can Low-Luminosity Galaxies Reionize the Universe?

NASA Astrophysics Data System (ADS)

Ferguson, Harry

2017-08-01

The prevailing wisdom is that low-luminosity galaxies are responsible for cosmic reionization. If this is true, then low-luminosity galaxies at high redshift have to be different from most of the low-luminosity galaxies studied to date at low redshift, which absorb too much of their ionizing radiation. While it is possible that high-z dwarf galaxies have the same metallicity at fixed mass and star-formation rate as low-redshift galaxies, they are different in one key respect. At fixed dark-halo mass, they are probably much denser (having collapsed earlier). This could lead to higher star-formation surface densities more capable of creating cavities in the ISM. But the denser halos of surrounding gas could be harder to clear. There is a critical need for further observations to validate and test physical models for the trends of escaping ionizing continuum with redshift, luminosity, and surface density. JWST will not be able to measure ionizing radiation during the epoch of reionization because the IGM absorbs most of the photons. To prepare for JWST, we need to use the ultraviolet capabilities of HST to measure diverse samples of galaxies at z<3, where we can see the photons and quantify the trends with other galaxy properties. As a complement to other studies, we propose to constrain the Lyman-continuum emission from 8 relatively low-luminosity strongly-lensed galaxies at 1

SU-G-BRB-09: Kompeito-Shot: Development of a Novel Verification System for 3D Beam Alignment Including the Sag of Gantry Head

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

Tsuneda, M; Nishio, T; Saito, A

Purpose: High accuracy of beam axis is required for high-precision radiation therapy. It is impossible to quantitatively and directly evaluate the sagging effect of the gantry head using current methods (star-shot and Winston-Lutz tests) when the gantry head sags under the weight of MLC and X-Y jaws. We introduce a novel method “Kompeito-shot (3D star-shot)” for the verification of 3D beam alignment (3D isocentricity). This method enables direct measurement of the sagging effect. We developed the system and examined the concept of this system. Methods: The system composed of a plastic scintillator (PS), a truncated cone-shaped mirror, a plane mirrormore » and a CCD camera. Two types of PS were compared. One consisted of a column PS (Co system), the other consisted of a column PS inserted into a barrel PS with shading film in between (Co-Ba system). The system was irradiated with a 6-MV photon beam and the scintillation light was measured using the CCD camera through the mirror system. The gantry angle was set from 270 to 300 degrees to mimic the sagging of the gantry head for evaluating the accuracy of the system. The distance between a center of PS and entrance / exit points were calculated to analyze the gantry angle. And, the calculated gantry angle and the irradiated gantry angle were compared. Results: We compared the measured image of Co system and that of Co-Ba system. Entrance and exit areas were visualized clearly. The histogram showing the difference between the calculated gantry angle and the irradiated gantry angle was fitted with a Gaussian function. Mean and standard deviation of Co-Ba system were smaller than that of Co system by one order of magnitude. Conclusion: We developed the Kompeito-shot system and evaluated the accuracy of the system. The basic concept works for the verification of 3D isocentricity.« less

Q&A: The space poet

NASA Astrophysics Data System (ADS)

Hoffman, Jascha

2011-11-01

Tracy K. Smith has her head in the stars. Thanks to her late father's job as an engineer on the Hubble Space Telescope, the US poet gathers inspiration from astrophysics and cosmology. Published this year, her third collection, Life on Mars, explores the future of human life, the great beyond and her father's death. As she prepares for a poetry reading at the Space Telescope Science Institute in Baltimore, Maryland, Smith talks about the limits of space and time.

Diagnosis of malignant hypertension with ocular examination: a child case.

PubMed

Yıldırım, Adnan; Mehmet Türkcü, Fatih; Yüksel, Harun; Sahin, Alparslan; Cınar, Yasin; Caça, Ihsan

2014-01-01

A 12-year-old female patient was admitted to our clinic complaining about low vision. Bilateral optic disc edema, macular star, and preretinal hemorrhages were found in fundoscopic examination. In fundus fluorescein angiography, massive leakage in the late phase was seen in the optic nerve head and macular area. These findings were compatible with high-grade hypertensive retinopathy. The patient consulted with pediatrics and a diagnosis of vesicourethral reflux and malignant hypertension was made.

Real Time Ferrograph Development.

DTIC Science & Technology

1979-11-01

differential temperature of 65 0 C. Since opteo- electronic devices (photodiodes, photoresistors, etc.) have a maximum operating temperature around 85 0 C, it is...flow during the precipitation cycle. This regulator must keep the flow rate constant at any given temperature regardless of the differential pressure...across the sensing head. The pressure regulator achieved this by using the differential pressure across a fixed re;7trictor to move a bellows diaphragm

JPRS Report, China.

DTIC Science & Technology

1989-04-26

36 LABOR Labor Export Earnings Soar in 1988 [JINGRONG SHIBAO 2 Feb] 36 AGRICULTURE Chemical Fertilizer Plant Policy in Anhui [ANHUI RIBAO 18...treasury of the profit surpluses (that is surpluses after deducting certain fixed sinking funds of the plants and factories, as in the Soviet Union) or...transferring certain unsuccessful plant heads to another locality, they have perhaps not noticed the other side of this obvious drawback of the system

Limited Evaluation of Image Quality Produced by a Portable Head CT Scanner (CereTom) in a Neurosurgery Centre

PubMed Central

Abdullah, Ariz Chong; Adnan, Johari Siregar; Rahman, Noor Azman A.; Palur, Ravikant

2017-01-01

Introduction Computed tomography (CT) is the preferred diagnostic toolkit for head and brain imaging of head injury. A recent development is the invention of a portable CT scanner that can be beneficial from a clinical point of view. Aim To compare the quality of CT brain images produced by a fixed CT scanner and a portable CT scanner (CereTom). Methods This work was a single-centre retrospective study of CT brain images from 112 neurosurgical patients. Hounsfield units (HUs) of the images from CereTom were measured for air, water and bone. Three assessors independently evaluated the images from the fixed CT scanner and CereTom. Streak artefacts, visualisation of lesions and grey–white matter differentiation were evaluated at three different levels (centrum semiovale, basal ganglia and middle cerebellar peduncles). Each evaluation was scored 1 (poor), 2 (average) or 3 (good) and summed up to form an ordinal reading of 3 to 9. Results HUs for air, water and bone from CereTom were within the recommended value by the American College of Radiology (ACR). Streak artefact evaluation scores for the fixed CT scanner was 8.54 versus 7.46 (Z = −5.67) for CereTom at the centrum semiovale, 8.38 (SD = 1.12) versus 7.32 (SD = 1.63) at the basal ganglia and 8.21 (SD = 1.30) versus 6.97 (SD = 2.77) at the middle cerebellar peduncles. Grey–white matter differentiation showed scores of 8.27 (SD = 1.04) versus 7.21 (SD = 1.41) at the centrum semiovale, 8.26 (SD = 1.07) versus 7.00 (SD = 1.47) at the basal ganglia and 8.38 (SD = 1.11) versus 6.74 (SD = 1.55) at the middle cerebellar peduncles. Visualisation of lesions showed scores of 8.86 versus 8.21 (Z = −4.24) at the centrum semiovale, 8.93 versus 8.18 (Z = −5.32) at the basal ganglia and 8.79 versus 8.06 (Z = −4.93) at the middle cerebellar peduncles. All results were significant with P-value < 0.01. Conclusions Results of the study showed a significant difference in image quality produced by the fixed CT scanner and CereTom, with the latter being more inferior than the former. However, HUs of the images produced by CereTom do fulfil the recommendation of the ACR. PMID:28381933

LoCuSS: THE STEADY DECLINE AND SLOW QUENCHING OF STAR FORMATION IN CLUSTER GALAXIES OVER THE LAST FOUR BILLION YEARS

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

Haines, C. P.; Pereira, M. J.; Egami, E.

2013-10-01

We present an analysis of the levels and evolution of star formation activity in a representative sample of 30 massive galaxy clusters at 0.15 < z < 0.30 from the Local Cluster Substructure Survey, combining wide-field Spitzer/MIPS 24 μm data with extensive spectroscopy of cluster members. The specific SFRs of massive (M > or approx. 10{sup 10} M{sub ☉}) star-forming cluster galaxies within r{sub 200} are found to be systematically ∼28% lower than their counterparts in the field at fixed stellar mass and redshift, a difference significant at the 8.7σ level. This is the unambiguous signature of star formation inmore » most (and possibly all) massive star-forming galaxies being slowly quenched upon accretion into massive clusters, their star formation rates (SFRs) declining exponentially on quenching timescales in the range 0.7-2.0 Gyr. We measure the mid-infrared Butcher-Oemler effect over the redshift range 0.0-0.4, finding rapid evolution in the fraction (f{sub SF}) of massive (M{sub K} < – 23.1) cluster galaxies within r{sub 200} with SFRs > 3 M{sub ☉} yr{sup –1}, of the form f{sub SF}∝(1 + z){sup 7.6±1.1}. We dissect the origins of the Butcher-Oemler effect, revealing it to be due to the combination of a ∼3 × decline in the mean specific SFRs of star-forming cluster galaxies since z ∼ 0.3 with a ∼1.5 × decrease in number density. Two-thirds of this reduction in the specific SFRs of star-forming cluster galaxies is due to the steady cosmic decline in the specific SFRs among those field galaxies accreted into the clusters. The remaining one-third reflects an accelerated decline in the star formation activity of galaxies within clusters. The slow quenching of star formation in cluster galaxies is consistent with a gradual shut down of star formation in infalling spiral galaxies as they interact with the intracluster medium via ram-pressure stripping or starvation mechanisms. The observed sharp decline in star formation activity among cluster galaxies since z ∼ 0.4 likely reflects the increased susceptibility of low-redshift spiral galaxies to gas removal mechanisms as their gas surface densities decrease with time. We find no evidence for the build-up of cluster S0 bulges via major nuclear starburst episodes.« less

Synthesis of mouse centromere-targeted polyamides and physico-chemical studies of their interaction with the target double-stranded DNA.

PubMed

Nozeret, Karine; Bonan, Marc; Yarmoluk, Serguiy M; Novopashina, Darya S; Boutorine, Alexandre S

2015-09-01

Synthetic minor groove-binding pyrrole-imidazole polyamides labeled by fluorophores are promising candidates for fluorescence imaging of double-stranded DNA in isolated chromosomes or fixed and living cells. We synthesized nine hairpin and two head-to-head tandem polyamides targeting repeated sequences from mouse major satellites. Their interaction with synthetic target dsDNA has been studied by physico-chemical methods in vitro before and after coupling to various fluorophores. Great variability in affinities and fluorescence properties reveals a conclusion that these properties do not only rely on recognition rules, but also on other known and unknown structural factors. Individual testing of each probe is needed before cellular applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of air vessel on water hammer in high-head pumping station

NASA Astrophysics Data System (ADS)

Wang, L.; Wang, F. J.; Zou, Z. C.; Li, X. N.; Zhang, J. C.

2013-12-01

Effects of air vessel on water hammer process in a pumping station with high-head were analyzed by using the characteristics method. The results show that the air vessel volume is the key parameter that determines the protective effect on water hammer pressure. The maximum pressure in the system declines with increasing air vessel volume. For a fixed volume of air vessel, the shape of air vessel and mounting style, such as horizontal or vertical mounting, have little effect on the water hammer. In order to obtain good protection effects, the position of air vessel should be close to the outlet of the pump. Generally, once the volume of air vessel is guaranteed, the water hammer of a entire pipeline is effectively controlled.

The SDSS-III DR12 MARVELS radial velocity data release: the first data release from the multiple object Doppler exoplanet survey

NASA Astrophysics Data System (ADS)

Ge, Jian; Thomas, Neil B.; Li, Rui; Senan Seieroe Grieves, Nolan; Ma, Bo; de Lee, Nathan M.; Lee, Brian C.; Liu, Jian; Bolton, Adam S.; Thakar, Aniruddha R.; Weaver, Benjamin; SDSS-Iii Marvels Team

2015-01-01

We present the first data release from the SDSS-III Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS) through the SDSS-III DR12. The data include 181,198 radial velocity (RV) measurements for a total of 5520 different FGK stars with V~7.6-12, of which more than 80% are dwarfs and subdwarfs while remainders are GK giants, among a total of 92 fields nearly randomly spread out over the entire northern sky taken with a 60-object MARVELS dispersed fixed-delay interferometer instrument over four years (2008-2012). There were 55 fields with a total of 3300 FGK stars which had 14 or more observations over about 2-year survey window. The median number of observations for these plates is 27 RV measurements. This represents the largest homogeneous sample of precision RV measurements of relatively bright stars. In this first released data, a total of 18 giant planet candidates, 16 brown dwarfs, and over 500 binaries with additional 96 targets having RV variability indicative of a giant planet companion are reported. The released data were produced by the MARVELS finalized 1D pipeline. We will also report preliminary statistical results from the MARVELS 2D data pipeline which has produced a median RV precision of ~30 m/s for stable stars.

Satellite quenching time-scales in clusters from projected phase space measurements matched to simulated orbits

NASA Astrophysics Data System (ADS)

Oman, Kyle A.; Hudson, Michael J.

2016-12-01

We measure the star formation quenching efficiency and time-scale in cluster environments. Our method uses N-body simulations to estimate the probability distribution of possible orbits for a sample of observed Sloan Digital Sky Survey galaxies in and around clusters based on their position and velocity offsets from their host cluster. We study the relationship between their star formation rates and their likely orbital histories via a simple model in which star formation is quenched once a delay time after infall has elapsed. Our orbit library method is designed to isolate the environmental effect on the star formation rate due to a galaxy's present-day host cluster from `pre-processing' in previous group hosts. We find that quenching of satellite galaxies of all stellar masses in our sample (109-10^{11.5}M_{⊙}) by massive (> 10^{13} M_{⊙}) clusters is essentially 100 per cent efficient. Our fits show that all galaxies quench on their first infall, approximately at or within a Gyr of their first pericentric passage. There is little variation in the onset of quenching from galaxy-to-galaxy: the spread in this time is at most ˜2 Gyr at fixed M*. Higher mass satellites quench earlier, with very little dependence on host cluster mass in the range probed by our sample.

Search For Star Cluster Age Gradients Across Spiral Arms of Three LEGUS Disk Galaxies

NASA Astrophysics Data System (ADS)

Shabani, F.; Grebel, E. K.; Pasquali, A.; D'Onghia, E.; Gallagher, J. S.; Adamo, A.; Messa, M.; Elmegreen, B. G.; Dobbs, C.; Gouliermis, D. A.; Calzetti, D.; Grasha, K.; Elmegreen, D. M.; Cignoni, M.; Dale, D. A.; Aloisi, A.; Smith, L. J.; Tosi, M.; Thilker, D. A.; Lee, J. C.; Sabbi, E.; Kim, H.; Pellerin, A.

2018-05-01

One of the main theories for explaining the formation of spiral arms in galaxies is the stationary density wave theory. This theory predicts the existence of an age gradient across the arms. We use the stellar cluster catalogues of the galaxies NGC 1566, M51a, and NGC 628 from the Legacy Extragalactic UV Survey (LEGUS) program. In order to test for the possible existence of an age sequence across the spiral arms, we quantified the azimuthal offset between star clusters of different ages in our target galaxies. We found that NGC 1566, a grand-design spiral galaxy with bisymmetric arms and a strong bar, shows a significant age gradient across the spiral arms that appears to be consistent with the prediction of the stationary density wave theory. In contrast, M51a with its two well-defined spiral arms and a weaker bar does not show an age gradient across the arms. In addition, a comparison with non-LEGUS star cluster catalogues for M51a yields similar results. We believe that the spiral structure of M51a is not the result of a stationary density wave with a fixed pattern speed. Instead, tidal interactions could be the dominant mechanism for the formation of spiral arms. We also found no offset in the azimuthal distribution of star clusters with different ages across the weak spiral arms of NGC 628.

Neutron star Interior Composition Explorer (NICER)

NASA Image and Video Library

2017-12-08

NICER team members Takashi Okajima, Yang Soong, and Steven Kenyon apply epoxy to the X-ray concentrator mounts after alignment. The epoxy holds the optics assemblies fixed in position through the vibrations experienced during launch to the International Space Station. The payload’s 56 mirror assemblies concentrate X-rays onto silicon detectors to gather data that will probe the interior makeup of neutron stars, including those that appear to flash regularly, called pulsars. The Neutron star Interior Composition Explorer (NICER) is a NASA Explorer Mission of Opportunity dedicated to studying the extraordinary environments — strong gravity, ultra-dense matter, and the most powerful magnetic fields in the universe — embodied by neutron stars. An attached payload aboard the International Space Station, NICER will deploy an instrument with unique capabilities for timing and spectroscopy of fast X-ray brightness fluctuations. The embedded Station Explorer for X-ray Timing and Navigation Technology demonstration (SEXTANT) will use NICER data to validate, for the first time in space, technology that exploits pulsars as natural navigation beacons. Credit: NASA/Goddard/ Keith Gendreau NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

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

Steiner, A. W.; Gandolfi, S.; Fattoyev, F. J.

Here, we perform a systematic assessment of models for the equation of state (EOS) of dense matter in the context of recent neutron star mass and radius measurements to obtain a broad picture of the structure of neutron stars. We demonstrate that currently available neutron star mass and radius measurements provide strong constraints on moments of inertia, tidal deformabilities, and crust thicknesses. Moreover, a measurement of the moment of inertia of PSR J0737-3039A with a 10% error, without any other information from observations, will constrain the EOS over a range of densities to within 50% 60%. We find tidal deformabilitiesmore » between 0.6 and 6 1036 g cm 2 s 2 (to 95% confidence) for M = 1.4 M ⊙ , and any measurement which constrains this range will provide an important constraint on dense matter. The crustal fraction of the moment of inertia can be as large as 10% for M = 1.4 M ⊙ permitting crusts to have a large enough moment of inertia reservoir to explain glitches in the Vela pulsar even with a large amount of superfluid entrainment. Finally, due to the uncertainty in the equation of state, there is at least a 40% variation in the thickness of the crust for a fixed mass and radius, which implies that future simulations of the cooling of a neutron star crust which has been heated by accretion will need to take this variation into account.« less

Mental rotation of body parts and sensory temporal discrimination in fixed dystonia.

PubMed

Katschnig, Petra; Edwards, Mark J; Schwingenschuh, Petra; Aguirregomozcorta, Maria; Kägi, Georg; Rothwell, John C; Bhatia, Kailash P

2010-06-15

Fixed dystonia is an uncommon but severely disabling condition typically affecting young women following a minor peripheral injury. There is no evidence of any structural lesions of the central nervous system nor any clear peripheral nerve or root damage. Electrophysiological techniques such as short intracortical inhibition, cortical silent period and a plasticity inducing protocol have revealed similarities but also differences compared to classical mobile dystonia. To further explore the pathophysiology of fixed dystonia we compared mental rotation of body parts and sensory temporal discrimination in 11 patients with fixed dystonia, 11 patients with classical mobile dystonia and 10 healthy controls. In the mental rotation task subjects were presented with realistic photos of left or right hands, feet and the head of a young women with a black patch covering the left or the right eye in six different orientations. Subjects had to verbally report the laterality of the presented stimuli. To assess sensory temporal discrimination subjects were asked to discriminate whether pairs of visual, tactile (electrical), or visuo-tactile stimuli were simultaneous or sequential (temporal discrimination threshold) and in the latter case which stimulus preceded the other (temporal order judgement). In accordance with previous studies patients with mobile dystonia were abnormal in mental rotation and temporal discrimination, whereas patients with fixed dystonia were only impaired in mental rotation. Possible explanations for this deficit may include the influence of the abnormal body posture itself, a shared predisposing pathophysiology for mobile and fixed dystonia, or a body image disturbance. These findings add information to the developing pathophysiological picture of fixed dystonia. (c) 2010 Movement Disorder Society.

On the Appearance of Thresholds in the Dynamical Model of Star Formation

NASA Astrophysics Data System (ADS)

Elmegreen, Bruce G.

2018-02-01

The Kennicutt–Schmidt (KS) relationship between the surface density of the star formation rate (SFR) and the gas surface density has three distinct power laws that may result from one model in which gas collapses at a fixed fraction of the dynamical rate. The power-law slope is 1 when the observed gas has a characteristic density for detection, 1.5 for total gas when the thickness is about constant as in the main disks of galaxies, and 2 for total gas when the thickness is regulated by self-gravity and the velocity dispersion is about constant, as in the outer parts of spirals, dwarf irregulars, and giant molecular clouds. The observed scaling of the star formation efficiency (SFR per unit CO) with the dense gas fraction (HCN/CO) is derived from the KS relationship when one tracer (HCN) is on the linear part and the other (CO) is on the 1.5 part. Observations of a threshold density or column density with a constant SFR per unit gas mass above the threshold are proposed to be selection effects, as are observations of star formation in only the dense parts of clouds. The model allows a derivation of all three KS relations using the probability distribution function of density with no thresholds for star formation. Failed galaxies and systems with sub-KS SFRs are predicted to have gas that is dominated by an equilibrium warm phase where the thermal Jeans length exceeds the Toomre length. A squared relation is predicted for molecular gas-dominated young galaxies.

An ALMA view of star formation efficiency suppression in early-type galaxies after gas-rich minor mergers

NASA Astrophysics Data System (ADS)

van de Voort, Freeke; Davis, Timothy A.; Matsushita, Satoki; Rowlands, Kate; Shabala, Stanislav S.; Allison, James R.; Ting, Yuan-Sen; Sansom, Anne E.; van der Werf, Paul P.

2018-05-01

Gas-rich minor mergers contribute significantly to the gas reservoir of early-type galaxies (ETGs) at low redshift, yet the star formation efficiency (SFE; the star formation rate divided by the molecular gas mass) appears to be strongly suppressed following some of these events, in contrast to the more well-known merger-driven starbursts. We present observations with the Atacama Large Millimeter/submillimeter Array (ALMA) of six ETGs, which have each recently undergone a gas-rich minor merger, as evidenced by their disturbed stellar morphologies. These galaxies were selected because they exhibit extremely low SFEs. We use the resolving power of ALMA to study the morphology and kinematics of the molecular gas. The majority of our galaxies exhibit spatial and kinematical irregularities, such as detached gas clouds, warps, and other asymmetries. These asymmetries support the interpretation that the suppression of the SFE is caused by dynamical effects stabilizing the gas against gravitational collapse. Through kinematic modelling we derive high velocity dispersions and Toomre Q stability parameters for the gas, but caution that such measurements in edge-on galaxies suffer from degeneracies. We estimate merger ages to be about 100 Myr based on the observed disturbances in the gas distribution. Furthermore, we determine that these galaxies lie, on average, two orders of magnitude below the Kennicutt-Schmidt relation for star-forming galaxies as well as below the relation for relaxed ETGs. We discuss potential dynamical processes responsible for this strong suppression of star formation surface density at fixed molecular gas surface density.

The effects of the initial mass function on the chemical evolution of elliptical galaxies

NASA Astrophysics Data System (ADS)

De Masi, Carlo; Matteucci, F.; Vincenzo, F.

2018-03-01

We describe the use of our chemical evolution model to reproduce the abundance patterns observed in a catalogue of elliptical galaxies from the Sloan Digital Sky Survey Data Release 4. The model assumes ellipticals form by fast gas accretion, and suffer a strong burst of star formation followed by a galactic wind, which quenches star formation. Models with fixed initial mass function (IMF) failed in simultaneously reproducing the observed trends with the galactic mass. So, we tested a varying IMF; contrary to the diffused claim that the IMF should become bottom heavier in more massive galaxies, we find a better agreement with data by assuming an inverse trend, where the IMF goes from being bottom heavy in less massive galaxies to top heavy in more massive ones. This naturally produces a downsizing in star formation, favouring massive stars in largest galaxies. Finally, we tested the use of the integrated Galactic IMF, obtained by averaging the canonical IMF over the mass distribution function of the clusters where star formation is assumed to take place. We combined two prescriptions, valid for different SFR regimes, to obtain the Integrated Initial Mass Function values along the whole evolution of the galaxies in our models. Predicted abundance trends reproduce the observed slopes, but they have an offset relative to the data. We conclude that bottom-heavier IMFs do not reproduce the properties of the most massive ellipticals, at variance with previous suggestions. On the other hand, an IMF varying with galactic mass from bottom heavier to top heavier should be preferred.

Global Positioning Svstem (GPS) on International Space Station (ISS) and Crew Return Vehicle (CRV)

NASA Technical Reports Server (NTRS)

Gomez, Susan F.

2002-01-01

Both the International Space Station and Crew Return Vehicle desired to have GPS on their vehicles due to improve state determination over traditional ground tracking techniques used in the past for space vehicles. Both also opted to use GPS for attitude determination to save the expense of a star tracker. Both vehicles have stringent pointing requirements for roll, pitch, and heading, making a sun or earth sensor not a viable option since the heading is undetermined. This paper discusses the technical challenges associated with the implementation of GPS on both of these vehicles. ISS and CRY use the same GPS receiver, but have faced different challenges since the mission of each is di fferent. ISS will be discussed first, then CRY. The flight experiments flown on the Space Shuttle in support of these efforts is also discussed.

Comprehensive Analysis of Immunological Synapse Phenotypes Using Supported Lipid Bilayers.

PubMed

Valvo, Salvatore; Mayya, Viveka; Seraia, Elena; Afrose, Jehan; Novak-Kotzer, Hila; Ebner, Daniel; Dustin, Michael L

2017-01-01

Supported lipid bilayers (SLB) formed on glass substrates have been a useful tool for study of immune cell signaling since the early 1980s. The mobility of lipid-anchored proteins in the system, first described for antibodies binding to synthetic phospholipid head groups, allows for the measurement of two-dimensional binding reactions and signaling processes in a single imaging plane over time or for fixed samples. The fragility of SLB and the challenges of building and validating individual substrates limit most experimenters to ~10 samples per day, perhaps increasing this few-fold when examining fixed samples. Successful experiments might then require further days to fully analyze. We present methods for automation of many steps in SLB formation, imaging in 96-well glass bottom plates, and analysis that enables >100-fold increase in throughput for fixed samples and wide-field fluorescence. This increased throughput will allow better coverage of relevant parameters and more comprehensive analysis of aspects of the immunological synapse that are well reconstituted by SLB.