Application of dopplionograms and gonionograms to atmospheric gravity wave disturbances in the ionosphere

International Nuclear Information System (INIS)

Wright, J.W.; Pitteway, M.L.V.

1982-01-01

A sequence of digital ionograms is processed by dopplionogram and gonionogram methods. Together, these disclose a disturbance in the F region which descends in altitude with time. Two wavelike periods of the disturbance are evident. The Doppler and angle-of-arrival behavior are consistent with a semiquantitative model of the plasma perturbations caused by an internal atmospheric gravity wave

Studying the influence of strong meteorological disturbances in the Earth's lower atmosphere on variations of ionospheric parameters in the Asian region of Russia

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Chernigovskaya, Marina; Kurkin, Vladimir; Orlov, Igor; Oinats, Alexey; Sharkov, Eugenii

2010-05-01

Short-period temporal variations of ionospheric parameters were analyzed to study probabilities of manifestation of strong meteorological disturbances in the Earth's lower atmosphere in variations of upper atmosphere parameters in a zone far removed from a disturbance source. In the analysis, we used data on maximum observed frequencies (MOF) of oblique sounding (OS) signals along Norilsk-Irkutsk, Magadan-Irkutsk, and Khabarovsk-Irkutsk paths in East Siberia and the Far East. These data were obtained during solar minimum at equinoxes (March, September) in 2008-2009. Analyzing effects of wave disturbances in ionospheric parameters, we take into account helio-geomagnetic and meteorological conditions in regions under study to do an effective separation between disturbances associated with magnetospheric-ionospheric coupling and those induced by the influence of the lower atmosphere on the upper one. The frequency analysis we conducted revealed time intervals with higher intensity of short-period oscillations which may have been interpreted as manifestation of large-scale traveling ionospheric disturbances (TIDs) whose sources were internal gravity waves (IGWs) with periods of 1-5 hours. The complex analysis of helio-geomagnetic, ionospheric, and atmospheric data as well as data on tropical cyclones established that the detected TIDs were unrelated to helio-geomagnetic disturbances (2008-2009 exhibited solar minimum and quiet geomagnetic conditions). The analysis of other potential sources of the observed short-period wave disturbances shows that observed TIDs do not always coincide in time with passage of local meteorological fronts through the region of subionospheric points of OS paths and are not associated with passage of solar terminator. An attempt was made to connect a number of detected TIDs with ionospheric responses to tropical cyclones (TC) which were in active phase in the north-west of the Pacific Ocean during the periods considered. A considerable

Large-Scale Traveling Weather Systems in Mars’ Southern Extratropics

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Hollingsworth, Jeffery L.; Kahre, Melinda A.

2017-10-01

Between late fall and early spring, Mars’ middle- and high-latitude atmosphere supports strong mean equator-to-pole temperature contrasts and an accompanying mean westerly polar vortex. Observations from both the MGS Thermal Emission Spectrometer (TES) and the MRO Mars Climate Sounder (MCS) indicate that a mean baroclinicity-barotropicity supports intense, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). Such extratropical weather disturbances are critical components of the global circulation as they serve as agents in the transport of heat and momentum, and generalized scalar/tracer quantities (e.g., atmospheric dust, water-vapor and ice clouds). The character of such traveling extratropical synoptic disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a moderately high-resolution Mars global climate model (Mars GCM). This Mars GCM imposes interactively-lifted and radiatively-active dust based on a threshold value of the surface stress. The model exhibits a reasonable "dust cycle" (i.e., globally averaged, a dustier atmosphere during southern spring and summer occurs). Compared to the northern-hemisphere counterparts, the southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather are investigated, in addition to large-scale up-slope/down-slope flows and the diurnal cycle. A southern storm zone in late winter and early spring presents in the western hemisphere via orographic influences from the Tharsis highlands, and the Argyre and Hellas impact basins. Geographically localized transient-wave activity diagnostics are constructed that illuminate dynamical differences amongst the simulations and these are presented.

Large-Scale Traveling Weather Systems in Mars Southern Extratropics

Science.gov (United States)

Hollingsworth, Jeffery L.; Kahre, Melinda A.

2017-01-01

Between late fall and early spring, Mars' middle- and high-latitude atmosphere supports strong mean equator-to-pole temperature contrasts and an accompanying mean westerly polar vortex. Observations from both the MGS Thermal Emission Spectrometer (TES) and the MRO Mars Climate Sounder (MCS) indicate that a mean baroclinicity-barotropicity supports intense, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). Such extratropical weather disturbances are critical components of the global circulation as they serve as agents in the transport of heat and momentum, and generalized scalar/tracer quantities (e.g., atmospheric dust, water-vapor and ice clouds). The character of such traveling extratropical synoptic disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a moderately high-resolution Mars global climate model (Mars GCM). This Mars GCM imposes interactively-lifted and radiatively-active dust based on a threshold value of the surface stress. The model exhibits a reasonable "dust cycle" (i.e., globally averaged, a dustier atmosphere during southern spring and summer occurs). Compared to the northern-hemisphere counterparts, the southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather are investigated, in addition to large-scale up-slope/down-slope flows and the diurnal cycle. A southern storm zone in late winter and early spring presents in the western hemisphere via orographic influences from the Tharsis highlands, and the Argyre and Hellas impact basins. Geographically localized transient-wave activity diagnostics are constructed that illuminate dynamical differences amongst the simulations and these are presented.

Penetration of internal gravity waveguide modes into the upper atmosphere

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Rudenko G.V.

2016-03-01

Full Text Available The paper describes internal gravity waveguide modes, using dissipative solutions above the source. We compare such a description with an accurate approach and a WKB approximation for dissipationless equations. For waveguide disturbances, dispersion relations calculated by any method are shown to be close to each other and to be in good agreement with observed characteristics of traveling ionospheric disturbances. Unlike other methods, dissipative solutions above the source allow us to adequately describe the spatial structure of disturbances in the upper atmosphere.

Wind effect on the motion of medium-scale travelling ionospheric disturbances in the E region of the ionosphere

International Nuclear Information System (INIS)

Kikvilashvili, G.B.; Sharadze, Z.S.; Mosashvili, N.V.

1988-01-01

Madium-scale travelling ionospheric disturbances (MSTID) in the ionosphere E region in Tbilisi area are investigated by means of spectral analysis of f 0 E s and f b E s variations, synchronously recorded in the three scattered points. The winds at the E s layers formation heights were measured simultaneously by D1 method in one of these points. It is established, that the MSTID motion direction in summer-time E region is controlled by the background thermospheric winds: disturbances mostly more across and against the wind. Tidal winds make the main contribution into the MSTID rate day variations

Seismo-Traveling Ionospheric Disturbances Triggered by the 12 May 2008 M 8.0 Wenchuan Earthquake

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Jann-Yenq Liu

2012-01-01

Full Text Available A network of 6 ground-based GPS receivers in East Asia was employed to study seismo-traveling ionospheric disturbances (STIDs triggered by an M 8.0 earthquake which occurred at Wenchuan on 12 May 2008. The network detected 5 STIDs on the south side of the epicenter area. A study on the distances of the detected STIDs to the epicenter versus their associated traveling times shows that the horizontal speed is about 600 m s-1. Applying the circle method, we find that the 5 circles intercept at a point right above the epicenter when the horizontal speed of 600 m s-1 is given. Global searches of the ray-tracing and the beam-forming techniques confirm that the STIDs are induced by vertical motions in the Earth¡¦s surface during the Wenchuan Earthquake.

Concentric traveling ionospheric disturbances triggered by the launch of a SpaceX Falcon 9 rocket

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Lin, Charles C. H.; Shen, Ming-Hsueh; Chou, Min-Yang; Chen, Chia-Hung; Yue, Jia; Chen, Po-Cheng; Matsumura, Mitsuru

2017-08-01

We report the first observation of concentric traveling ionospheric disturbances (CTIDs) triggered by the launch of a SpaceX Falcon 9 rocket on 17 January 2016. The rocket-triggered ionospheric disturbances show shock acoustic wave signature in the time rate change (time derivative) of total electron content (TEC), followed by CTIDs in the 8-15 min band-pass filtering of TEC. The CTIDs propagated northward with phase velocity of 241-617 m/s and reached distances more than 1000 km away from the source on the rocket trajectory. The wave characteristics of CTIDs with periods of 10.5-12.7 min and wavelength 200-400 km agree well with the gravity wave dispersion relation. The optimal wave source searching and gravity wave ray tracing technique suggested that the CTIDs have multiple sources which are originated from 38-120 km altitude before and after the ignition of the second-stage rocket, 200 s after the rocket was launched.

Medium-scale traveling ionospheric disturbances triggered by Super Typhoon Nepartak (2016)

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Chou, M. Y.; Lin, C. C. H.; Yue, J.; Chang, L. C.; Tsai, H. F.; Chen, C. H.

2017-12-01

Two remarkable typhoon-induced traveling ionospheric disturbances (TIDs) with concentric andnorthwest-southeast (NW-SE) alignments, respectively, associated with concentric gravity waves (CGWs) andionospheric instabilities possibly seeded by CGWs, were observed in total electron content (TEC) derived fromground-based Global Navigation Satellite System networks in Taiwan and Japan when the Category 5 SuperTyphoon Nepartak approached Taiwan on 7 July 2016. The concentric TIDs (CTIDs) first appear withhorizontal phase velocities of 161-200 m/s, horizontal wavelengths of 160-270 km, and periods of 15-22 min during 08:00-11:20 UT. Following the CTIDs, the NW-SE aligned nighttime medium-scale TIDs(MSTIDs) are formed on the west edge of the CTIDs over the Taiwan Strait during 11:30-14:00 UT. It issuggested that the MSTIDs are produced by the electrodynamical coupling of Perkins instability andCGW-induced polarization electric fields. This study proposes connections of typhoon-induced CTIDs andsubsequently occurring MSTIDs in the low-latitude ionosphere.

Observation of seasonal effects in traveling ionospheric disturbances by the directional deviation technique

International Nuclear Information System (INIS)

Walton, E.K.; Bailey, A.D.

1976-01-01

An experiment was performed during the years 1962 through 1964 in which direction of arrival data were collected on pulse signals received over a 450 km east-west path. In order to determine the effect that traveling ionospheric disturbances (TIDs) had on these data, a ''corrugation'' model was proposed. The corrugation model assumes that TIDs can be treated as if they were moving cylindrical sinusoidal perturbations on the ionospheric reflecting surface. Lateral deviations in the experimental data of the type predicted by this model were found to be quite common. Variations in the detected TIDs as a function of time of year were found to be consistent with the ''seasonal effect'' studied by Munro in 1958, Jones 1969, and Davies and Jones in 1971

GPS network observation of traveling ionospheric disturbances following the Chelyabinsk meteorite blast

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F. Ding

2016-11-01

Full Text Available We use the Global Positioning System (GPS network in northwest China and central Asia to monitor traveling ionospheric disturbances (TIDs, which were possibly excited by the large meteorite blast over Chelyabinsk, Russia, on 15 February 2013. Two TIDs were observed. The first TID was observed 13 min after the blast within a range of 270–600 km from the blast site. It propagated radially from the blast site with a mean velocity and period of 369 m s−1 and 12 min, respectively. The second TID was found in northwest China, 1.5 h after the time of the blast, at  ∼  2500–3100 km from the blast site. This latter TID propagated southeastward with a velocity and period of 410 m s−1 and 23 min, respectively. Severe dissipation of the perturbation total electronic content (TEC amplitude was observed. Any TIDs propagating in a global range was not found after the meteorite blast. Features of TIDs were compared with those excited by early nuclear explosion tests. It is inferred from our analysis that the energy release of the Chelyabinsk meteorite blast may not be large enough to excite such ionospheric disturbances in a global range as some nuclear explosions did.

PSO-based PID Speed Control of Traveling Wave Ultrasonic Motor under Temperature Disturbance

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Arifin Mat Piah, Kamal; Yusoff, Wan Azhar Wan; Azmi, Nur Iffah Mohamed; Romlay, Fadhlur Rahman Mohd

2018-03-01

Traveling wave ultrasonic motors (TWUSMs) have a time varying dynamics characteristics. Temperature rise in TWUSMs remains a problem particularly in sustaining optimum speed performance. In this study, a PID controller is used to control the speed of TWUSM under temperature disturbance. Prior to developing the controller, a linear approximation model which relates the speed to the temperature is developed based on the experimental data. Two tuning methods are used to determine PID parameters: conventional Ziegler-Nichols(ZN) and particle swarm optimization (PSO). The comparison of speed control performance between PSO-PID and ZN-PID is presented. Modelling, simulation and experimental work is carried out utilizing Fukoku-Shinsei USR60 as the chosen TWUSM. The results of the analyses and experimental work reveal that PID tuning using PSO-based optimization has the advantage over the conventional Ziegler-Nichols method.

AK SCO, FIRST DETECTION OF A HIGHLY DISTURBED ATMOSPHERE IN A PRE-MAIN-SEQUENCE CLOSE BINARY

International Nuclear Information System (INIS)

Gomez de Castro, Ana I.

2009-01-01

AK Sco is a unique source: a ∼10 Myr old pre-main-sequence (PMS) spectroscopic binary composed of two nearly equal F5 stars that at periastron are separated by barely 11 stellar radii, so the stellar magnetospheres fill the Roche lobe at periastron. The orbit is not yet circularized (e = 0.47) and very strong tides are expected. This makes AK Sco the ideal laboratory to study the effect of gravitational tides in the stellar magnetic field building up during PMS evolution. In this Letter, the detection of a highly disturbed (σ ≅ 100 km s -1 ) and very dense atmosphere (n e = 1.6 x 10 10 cm -3 ) is reported. Significant line broadening blurs any signs of ion belts or bow shocks in the spectrum of the atmospheric plasma. The radiative losses cannot be accounted for solely by the dissipation of energy from the tidal wave propagating in the stellar atmosphere or by the accreting material. The release of internal energy from the star seems to be the most likely source of the plasma heating. This is the first clear indication of a highly disturbed atmosphere surrounding a PMS close binary.

AK Sco, First Detection of a Highly Disturbed Atmosphere in a Pre-Main-Sequence Close Binary

Science.gov (United States)

Gómez de Castro, Ana I.

2009-06-01

AK Sco is a unique source: a ~10 Myr old pre-main-sequence (PMS) spectroscopic binary composed of two nearly equal F5 stars that at periastron are separated by barely 11 stellar radii, so the stellar magnetospheres fill the Roche lobe at periastron. The orbit is not yet circularized (e = 0.47) and very strong tides are expected. This makes AK Sco the ideal laboratory to study the effect of gravitational tides in the stellar magnetic field building up during PMS evolution. In this Letter, the detection of a highly disturbed (σ sime 100 km s-1) and very dense atmosphere (n e = 1.6 × 1010 cm-3) is reported. Significant line broadening blurs any signs of ion belts or bow shocks in the spectrum of the atmospheric plasma. The radiative losses cannot be accounted for solely by the dissipation of energy from the tidal wave propagating in the stellar atmosphere or by the accreting material. The release of internal energy from the star seems to be the most likely source of the plasma heating. This is the first clear indication of a highly disturbed atmosphere surrounding a PMS close binary.

Sounding rocket/ground-based observation campaign to study Medium-Scale Traveling Ionospheric Disturbances (MSTID)

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Yamamoto, M.; Yokoyama, T.; Saito, A.; Otsuka, Y.; Yamamoto, M.; Abe, T.; Watanabe, S.; Ishisaka, K.; Saito, S.; Larsen, M.; Pfaff, R. F.; Bernhardt, P. A.

2012-12-01

An observation campaign is under preparation. It is to launch sounding rockets S-520-27 and S-310-42 from Uchinoura Space Center of JAXA while ground-based instruments measure waves in the ionosphere. It is scheduled in July/August 2013. The main purpose of the experiment is to reveal generation mechanism of Medium-Scale Traveling Ionospheric Disturbance (MSTID). The MSTID is the ionospheric wave with 1-2 hour periodicity, 100-200 km horizontal wavelength, and southwestward propagation. It is enhanced in the summer nighttime of the mid-latitude ionosphere. The MSTID is not only a simple atmospheric-wave modulation of the ionosphere, but shows similarity to characteristics of the Perkins instability. A problem is that growth rate of the Perkins instability is too small to explain the phenomena. We now hypothesize a generation mechanism that electromagnetic coupling of the F- and E-regions help rapid growth of the MSTID especially at its initial stage. In the observation campaign, we will use the sounding rocket S-520-27 for in-situ measurement of ionospheric parameters, i.e., electron density and electric fields. Wind velocity measurements in both F- and E-regions are very important as well. For the F-region winds, we will conduct Lithium-release experiment under the full-moon condition. This is a big technical challenge. Another rocket S-310-42 will be used for the E-region wind measurement with the TMA release. On the ground, we will use GEONET (Japanese vast GPS receiver network) to monitor horizontal distribution of GPS-TEC on the realtime bases. In the presentation we will show MSTID characteristics and the proposed generation mechanism, and discuss plan and current status of the project.

Discovering Coseismic Traveling Ionospheric Disturbances Generated by the 2016 Kaikoura Earthquake

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Li, J. D.; Rude, C. M.; Gowanlock, M.; Pankratius, V.

2017-12-01

Geophysical events and hazards, such as earthquakes, tsunamis, and volcanoes, have been shown to generate traveling ionospheric disturbances (TIDs). These disturbances can be measured by means of Total Electron Content fluctuations obtained from a network of multifrequency GPS receivers in the MIT Haystack Observatory Madrigal database. Analyzing the response of the ionosphere to such hazards enhances our understanding of natural phenomena and augments our large-scale monitoring capabilities in conjunction with other ground-based sensors. However, it is currently challenging for human investigators to spot and characterize such signatures, or whether a geophysical event has actually occurred, because the ionosphere can be noisy with multiple simultaneous phenomena taking place at the same time. This work therefore explores a systematic pipeline for the ex-post discovery and characterization of TIDs. Our technique starts by geolocating the event and gathering the corresponding data, then checks for potentially conflicting TID sources, and processes the raw total electron content data to generate differential measurements. A Kolmogorov-Smirnov test is applied to evaluate the statistical significance of detected deviations in the differential measurements. We present results from our successful application of this pipeline to the 2016 7.8 Mw Kaikoura earthquake occurring in New Zealand on November 13th. We detect a coseismic TID occurring 8 minutes after the earthquake and propagating towards the equator at 1050 m/s, with a 0.22 peak-to-peak TECu amplitude. Furthermore, the observed waveform exhibits more complex behavior than the expected N-wave for a coseismic TID, which potentially results from the complex multi-fault structure of the earthquake. We acknowledge support from NSF ACI1442997 (PI Pankratius), NASA AISTNNX15AG84G (PI Pankratius), and NSF AGS-1343967 (PI Pankratius), and NSF AGS-1242204 (PI Erickson).

Climatology of medium-scale traveling ionospheric disturbances observed by the midlatitude Blackstone SuperDARN radar

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Frissell, N. A.; Baker, J. B. H.; Ruohoniemi, J. M.; Gerrard, A. J.; Miller, E. S.; Marini, J. P.; West, M. L.; Bristow, W. A.

2014-09-01

A climatology of daytime midlatitude medium-scale traveling ionospheric disturbances (MSTIDs) observed by the Blackstone Super Dual Auroral Radar Network (SuperDARN) radar is presented. MSTIDs were observed primarily from fall through spring. Two populations were observed: a dominant population heading southeast (centered at 147° geographic azimuth, ranging from 100° to 210°) and a secondary population heading northwest (centered at -50° azimuth, ranging from -75° to -25°). Horizontal velocities ranged from 50 to 250 m s-1 with a distribution maximum between 100 and 150 m s-1. Horizontal wavelengths ranged from 100 to 500 km with a distribution peak at 250 km, and periods between 23 and 60 min, suggesting that the MSTIDs may be consistent with thermospheric gravity waves. A local time (LT) dependence was observed such that the dominant (southeastward) population decreased in number as the day progressed until a late afternoon increase. The secondary (northwestward) population appeared only in the afternoon, possibly indicative of neutral wind effects or variability of sources. LT dependence was not observed in other parameters. Possible solar-geomagnetic and tropospheric MSTID sources were considered. The auroral electrojet (AE) index showed a correlation with MSTID statistics. Reverse ray tracing with the HINDGRATS model indicates that the dominant population has source regions over the Great Lakes and near the geomagnetic cusp, while the secondary population source region is 100 km above the Atlantic Ocean east of the Carolinas. This suggests that the dominant population may come from a region favorable to either tropospheric or geomagnetic sources, while the secondary population originates from a region favorable to secondary waves generated via lower atmospheric convection.

Ionospheric Disturbances Triggered by the Mw7.6 Earthquake off the Coast of El Salvador on 13 January 2001

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Ting-Kuo Jung

2006-01-01

Full Text Available A network of five ground-based receivers of the global positioning sys- tem (GPS was use to detect seismo-ionospheric disturbances in the total elec- tron content (TEC triggered by the 13 January 2001 El Salvador Mw 7.6 earthquake. We apply least square fitted analysis as well as beam forming and ray tracing methods to analyze the GPS TECs. Results show that the average speeds of the seismo-ionospheric disturbances traveling in the up- per atmosphere and ionosphere lie between 360 and 570 m s−1 , and the disturbance origins on the ground derived by the two methods are near the epicenter reported by the U.S. Geological Survey (USGS.

A Comparison of High Frequency Angle of Arrival and Ionosonde Data During a Traveling Ionospheric Disturbance

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Knippling, K.; Nava, O.; Emmons, D. J., II; Dao, E. V.

2017-12-01

Geolocation techniques are used to track the source of uncooperative high frequency emitters. Traveling ionospheric disturbances (TIDs) make geolocation particularly difficult due to large perturbations in the local ionospheric electron density profiles. Angle of arrival(AoA) and ionosonde virtual height measurements collected at White Sands Missile Range, New Mexico in January, 2014 are analyzed during a medium scale TID (MSTID). MSTID characteristics are extracted from the measurements, and a comparison between the data sets is performed, providing a measure of the correlation as a function of distance between the ionosonde and AoA circuit midpoints. The results of this study may advance real-time geolocation techniques through the implementation of a time varying mirror model height.

Tools for determining critical levels of atmospheric ammonia under the influence of multiple disturbances

International Nuclear Information System (INIS)

Pinho, P.; Llop, E.; Ribeiro, M.C.; Cruz, C.; Soares, A.; Pereira, M.J.; Branquinho, C.

2014-01-01

Critical levels (CLEs) of atmospheric ammonia based on biodiversity changes have been mostly calculated using small-scale single-source approaches, to avoid interference by other factors, which also influence biodiversity. Thus, it is questionable whether these CLEs are valid at larger spatial scales, in a multi- disturbances context. To test so, we sampled lichen diversity and ammonia at 80 sites across a region with a complex land-cover including industrial and urban areas. At a regional scale, confounding factors such as industrial pollutants prevailed, masking the CLEs. We propose and use a new tool to calculate CLEs by stratifying ammonia concentrations into classes, and focusing on the highest diversity values. Based on the significant correlations between ammonia and biodiversity, we found the CLE of ammonia for Mediterranean evergreen woodlands to be 0.69 μg m −3 , below the previously accepted value of 1.9 μg m −3 , and below the currently accepted pan-European CLE of 1.0 μg m −3 . - Highlights: • Biodiversity responds to multiple disturbances. • This prevents calculation regional critical levels of atmospheric ammonia. • We propose a tool to overcome that, based on the maximum biodiversity observed. • Critical level for Mediterranean evergreen woodlands was revised down to 0.69 μg m −3 . - Critical levels of atmospheric ammonia have not been calculated at a regional scale. Using a new method, we revised down the current Mediterranean evergreen woodlands critical level to 0.69 μg m −3

Approaches to groundwater travel time

International Nuclear Information System (INIS)

Kaplan, P.; Klavetter, E.; Peters, R.

1989-01-01

One of the objectives of performance assessment for the Yucca Mountain Project is to estimate the groundwater travel time at Yucca Mountain, Nevada, to determine whether the site complies with the criteria specified in the Code of Federal Regulations, Title 10 CFR 60.113 (a). The numerical standard for performance in these criteria is based on the groundwater travel time along the fastest path of likely radionuclide transport from the disturbed zone to the accessible environment. The concept of groundwater travel time as proposed in the regulations, does not have a unique mathematical statement. The purpose of this paper is to discuss the ambiguities associated with the regulatory specification of groundwater travel time, two different interpretations of groundwater travel time, and the effect of the two interpretations on estimates of the groundwater travel time

Traveling-Wave Tube Amplifier Second Harmonic as Millimeter-Wave Beacon Source for Atmospheric Propagation Studies

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Simons, Rainee N.; Wintucky, Edwin G.

2014-01-01

This paper presents the design and test results of a CW millimeter-wave satellite beacon source, based on the second harmonic from a traveling-wave tube amplifier and utilizes a novel waveguide multimode directional coupler. A potential application of the beacon source is for investigating the atmospheric effects on Q-band (37-42 GHz) and V/W-band (71- 76 GHz) satellite-to-ground signals.

Approaches to groundwater travel time

International Nuclear Information System (INIS)

Kaplan, P.; Klavetter, E.; Peters, R.

1989-01-01

One of the objectives of performance assessment for the Yucca Mountain Project is to estimate the groundwater travel time at Yucca Mountain, Nevada, to determine whether the site complies with the criteria specified in the Code of Federal Regulations. The numerical standard for performance in these criteria is based on the groundwater travel time along the fastest path of likely radionuclide transport from the disturbed zone to the accessible environment. The concept of groundwater travel time, as proposed in the regulations, does not have a unique mathematical statement. The purpose of this paper is to discuss (1) the ambiguities associated with the regulatory specification of groundwater travel time, (2) two different interpretations of groundwater travel time, and (3) the effect of the two interpretations on estimates of the groundwater travel time. 3 refs., 2 figs., 2 tabs

Acoustic-gravity waves generated by atmospheric and near-surface sources

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Kunitsyn, Viacheslav E.; Kholodov, Alexander S.; Krysanov, Boris Yu.; Andreeva, Elena S.; Nesterov, Ivan A.; Vorontsov, Artem M.

2013-04-01

Numerical simulation of the acoustic-gravity waves (AGW) generated by long-period oscillations of the Earth's (oceanic) surface, earthquakes, explosions, thermal heating, seiches, and tsunami is carried out. Wavelike disturbances are quite frequent phenomena in the atmosphere and ionosphere. These events can be caused by the impacts from space and atmosphere, by oscillations of the Earth'as surface and other near-surface events. These wavelike phenomena in the atmosphere and ionosphere appear as the alternating areas of enhanced and depleted density (in the atmosphere) or electron concentration (in the ionosphere). In the paper, AGW with typical frequencies of a few hertz - millihertz are analyzed. AGW are often observed after the atmospheric perturbations, during the earthquakes, and some time (a few days to hours) in advance of the earthquakes. Numerical simulation of the generation of AGW by long-period oscillations of the Earth's and oceanic surface, earthquakes, explosions, thermal heating, seiches, and tsunami is carried out. The AGW generated by the near-surface phenomena within a few hertz-millihertz frequency range build up at the mid-atmospheric and ionospheric altitudes, where they assume their typical spatial scales of the order of a few hundred kilometers. Oscillations of the ionospheric plasma within a few hertz-millihertz frequency range generate electromagnetic waves with corresponding frequencies as well as travelling ionospheric irregularities (TIDs). Such structures can be successfully monitored using satellite radio tomography (RT) techniques. For the purposes of RT diagnostics, 150/400 MHz transmissions from low-orbiting navigational satellites flying in polar orbits at the altitudes of about 1000 km as well as 1.2-1.5 GHz signals form high-orbiting (orbital altitudes about 20000 km) navigation systems like GPS/GLONASS are used. The results of experimental studies on generation of wavelike disturbances by particle precipitation are presented

Interpreting Observations of Large-Scale Traveling Ionospheric Disturbances by Ionospheric Sounders

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Pederick, L. H.; Cervera, M. A.; Harris, T. J.

2017-12-01

From July to October 2015, the Australian Defence Science and Technology Group conducted an experiment during which a vertical incidence sounder (VIS) was set up at Alice Springs Airport. During September 2015 this VIS observed the passage of many large-scale traveling ionospheric disturbances (TIDs). By plotting the measured virtual heights across multiple frequencies as a function of time, the passage of the TID can be clearly displayed. Using this plotting method, we show that all the TIDs observed during the campaign by the VIS at Alice Springs show an apparent downward phase progression of the crests and troughs. The passage of the TID can be more clearly interpreted by plotting the true height of iso-ionic contours across multiple plasma frequencies; the true heights can be obtained by inverting each ionogram to obtain an electron density profile. These plots can be used to measure the vertical phase speed of a TID and also reveal a time lag between events seen in true height compared to virtual height. To the best of our knowledge, this style of analysis has not previously been applied to other swept-frequency sounder observations. We develop a simple model to investigate the effect of the passage of a large-scale TID on a VIS. The model confirms that for a TID with a downward vertical phase progression, the crests and troughs will appear earlier in virtual height than in true height and will have a smaller apparent speed in true height than in virtual height.

Travelling Ionospheric Disturbances Observed During Sudden Stratospheric Warming, Equinox and Solstice Periods with Kharkiv and Millstone Hill Incoherent Scatter Radars

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Goncharenko, L. P.; Panasenko, S.; Aksonova, K.; Erickson, P. J.; Domnin, I. F.

2016-12-01

Travelling ionospheric disturbances (TIDs) play a key role in the coupling of different ionospheric regions through momentum an energy transfer. They are thought to be mostly associated with atmospheric gravity waves and are known to strongly affect radio propagation conditions. The incoherent scatter (IS) method enables TIDs detection in such ionospheric parameters as electron density, ion and electron temperatures, and plasma velocity along radar beam, thus providing critical information needed to examine different hypothesis about association of TIDs with their sources. In 2016, several joint measuring campaigns were conducted using Kharkiv (49.6 N, 36.4 E) and Millstone Hill (42.6 N, 288.5 E) IS radars. These campaigns covered the periods of sudden stratospheric warnings (SSW) in February, vernal equinox and summer solstice. For consistency, the data acquired by radars were processed using the same data analysis methods. The results obtained show the TIDs to be detected throughout all observation intervals in February measurements. The differences found in the behavior of TIDs over Kharkiv and Millstone Hill sites may be partially explained by variations in stratospheric wind velocity vectors during SSW period. As for March equinox and June solstice, the prevailing TIDs are observed near solar terminators. Their periods vary mostly in the range of 40 - 80 minutes, relative amplitudes are about 0.05 - 0.3 of the background electron density, and the maximum values are observed at the heights of 200 - 250 km. Systematic long-term observations of wave processes in the ionosphere with multiple IS facilities can reveal interhemispheric variability in TID parameters, give better understanding the mechanisms of TID generation and propagation, and improve regional and global ionospheric models.

Detection of Traveling Ionospheric Disturbances (TIDs) from various man-made sources using Global Navigation Satellite System (GNSS)

Science.gov (United States)

Helmboldt, J.; Park, J.; von Frese, R. R. B.; Grejner-Brzezinska, D. A.

2016-12-01

Traveling ionospheric disturbance (TID) is generated by various sources and detectable by observing the spatial and temporal change of electron contents in the ionosphere. This study focused on detecting and analyzing TIDs generated by acoustic-gravity waves from man-made events including underground nuclear explosions (UNEs), mine collapses, mine blasts, and large chemical explosions (LCEs) using Global Navigation Satellite System (GNSS). In this study we selected different types of events for case study which covers two US and three North Korean UNEs, two large US mine collapses, three large US mine blasts, and a LCE in northern China and a second LCE at the Nevada Test Site. In most cases, we successfully detected the TIDs as array signatures from the multiple nearby GNSS stations. The array-based TID signatures from these studies were found to yield event-appropriate TID propagation speeds ranging from about a few hundred m/s to roughly a km/s. In addition, the event TID waveforms, and propagation angles and directions were established. The TID waveforms and the maximum angle between each event and the IPP of its TID with the longest travel distance from the source may help differentiate UNEs and LCEs, but the uneven distributions of the observing GNSS stations complicates these results. Thus, further analysis is required of the utility of the apertures of event signatures in the ionosphere for discriminating these events. In general, the results of this study show the potential utility of GNSS observations for detecting and mapping the ionospheric signatures of large-energy anthropological explosions and subsurface collapses.

The instability of internal gravity waves to localised disturbances

Directory of Open Access Journals (Sweden)

J. Vanneste

1995-02-01

Full Text Available The instability of an internal gravity wave due to nonlinear wave-wave interaction is studied theoretically and numerically. Three different aspects of this phenomenon are examined. 1. The influence of dissipation on both the resonant and the nonresonant interactions is analysed using a normal mode expansion of the basic equations. In particular, the modifications induced in the interaction domain are calculated and as a result some modes are shown to be destabilised by dissipation. 2. The evolution of an initial unstable disturbance of finite vertical extent is described as the growth of two secondary wave packets travelling at the same group velocity. A quasi-linear correction to the basic primary wave is calculated, corresponding to a localised amplitude decrease due to the disturbance growth. 3. Numerical experiments are carried out to study the effect of a basic shear on wave instability. It appears that the growing secondary waves can have a frequency larger than that of the primary wave, provided that the shear is sufficient. The instability of waves with large amplitude and long period, such as tides or planetary waves, could therefore be invoked as a possible mechanism for the generation of gravity waves with shorter period in the middle atmosphere.

Detection of Traveling Ionospheric Disturbances by Medium Frequency Doppler Sounding Using AM Radio Transmissions

Science.gov (United States)

Chilcote, M. A.; Labelle, J. W.; Lind, F. D.; Coster, A. J.; Galkin, I. A.; Miller, E.; Weatherwax, A. T.

2013-12-01

Nighttime traveling ionosphere disturbances (TIDs) propagating in the lower F region of the ionosphere were detected from time variations in the Doppler shifts of commercial AM radio broadcast stations. Three separately deployed receivers, components of the Intercepted Signals for Ionospheric Science (ISIS) Array software radio instrumentation network, recorded signals from two radio stations during eleven nights in March-April, 2012. Combining these measurements established that variations in the frequencies of the received signals, with amplitudes up to a few tenths of a Hertz, resulted from Doppler shifts produced by the ionosphere. At times, TIDs were detected as large amplitude variations in the Doppler shift with approximately 40-minute period correlated across the array. For one study interval, 0000-0400 UT on April 13, 2012, simultaneous GPS-TEC, digisonde, and superDARN coherent backscatter radar measurements confirmed the detection of TIDs with the same period. Detection of the AM signals at widely spaced receivers allowed the phase velocity and wavelength of the TIDs to be inferred, with some limitations due to differing reflection heights for the different frequencies. These measurements will be compared to phase velocities and wavelengths determined from combining an array of GPS receivers; discrepancies due to the altitude sensitivity of the techniques or other effects will be discussed. These results demonstrate that AM radio signals can be used for detection of nighttime TIDs.

Sudden Ionospheric Disturbances (SID)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Sudden ionospheric disturbances (SID) are caused by solar flare enhanced X-rays in the 1 to 10 angstrom range. Solar flares can produce large increases of ionization...

Large-amplitude traveling ionospheric distrubance produced by the May 18, 1980, explosion of Mount St. Helens

International Nuclear Information System (INIS)

Roberts, D.H.; Klobuchar, J.A.; Fougere, P.F.; Hendrickson, D.H.

1982-01-01

A remarkable long-lived, large-scale traveling ionospheric disturbance (TID), excited by the May 18, 1980, explosion of Mount St. Helens, has been detected in total electron content monitor data. Oscillatory perturbations in the electron column density of the ionosphere with amplitudes about 10% of the nominal daytime content were detected at three stations whose ionospheric penetration points lie between 1610 and 1890 km from Mount St. Helens. Smaller perturbations were detected at five of six additional stations between 3760 and 4950 km away. The period of the TID increased linearly with great-circle distance from Mount St. Helens, ranging from roughly-equal37 min at the nearest station to roughly-equal116 min at the most distant one. The TID persisted for at least four cycles at the three close stations and three cycles at the more distant stations and was qualitatively similar to TID's produced by the low-altitude thermonuclear detonations of the 1960's. The disturbance front of this TID accelerated from an average velocity of roughly-equal350 m/s between Mt. St. Helens and the close stations to an average velocity of roughly-equal550 m/s to the more distant ones.A model based on the free wave response of an isothermal atmosphere to a point disturbance provides a good fit to the data at the three closest stations, but no such model can account for all of the data. Modeling of the long-distance behavior of the Mount St. Helens TID in terms of upper-atmosphere guided gravity waves is complicated by the requirement of exciting them by a ground-level explosion. There was no evidence for a strong supersonic shock wave in the ionosphere. As a result, the Mount St. Helens disturbance may prove to be a cleaner test of detailed theories of the point excitation and propagation of gravity waves in a realistic atmosphere than were TID's excited by thermonuclear weapons

Ionospheric irregularities in periods of meteorological disturbances

Science.gov (United States)

Borchevkina, O. P.; Karpov, I. V.

2017-09-01

The results of observations of the total electron content (TEC) in periods of storm disturbances of meteorological situation are presented in the paper. The observational results have shown that a passage of a meteorological storm is accompanied by a substantial decrease in values of TEC and critical frequencies of the ionospheric F2 region. The decreases in values of these ionospheric parameters reach 50% and up to 30% in TEC and critical frequency of the F2 layer, respectively, as compared to meteorologically quiet days. Based on qualitative analysis, it is found that the processes related to formation of local regions of thermospheric heating due to a dissipation of AGW coming into the upper atmosphere from the region of the meteorological disturbance in the lower atmosphere are a possible cause of these ionospheric disturbances.

Children and Moods in Hans Christian Andersen's Travel Books

DEFF Research Database (Denmark)

Jensen, Lars Bo

2008-01-01

A categorization of moods, atmospheres and motifs connected with the children in Hans Christian Andersen’s five travel books (1831-1868). Surprisingly, death and darkness and, on the other side, eroticism and (red) light are the dominant two categories.......A categorization of moods, atmospheres and motifs connected with the children in Hans Christian Andersen’s five travel books (1831-1868). Surprisingly, death and darkness and, on the other side, eroticism and (red) light are the dominant two categories....

Large-scale traveling ionospheric disturbances observed using GPS receivers over high-latitude and equatorial regions

Science.gov (United States)

Idrus, Intan Izafina; Abdullah, Mardina; Hasbi, Alina Marie; Husin, Asnawi; Yatim, Baharuddin

2013-09-01

This paper presents the first results of large-scale traveling ionospheric disturbances (LSTIDs) observation during two moderate magnetic storm events on 28 May 2011 (SYM-H∼ -94 nT and Dst∼-80 nT) and 6 August 2011 (SYM-H∼-126 nT and Dst∼-113 nT) over the high-latitude region in Russia, Sweden, Norway, Iceland and Greenland and equatorial region in the Peninsular Malaysia using vertical total electron content (VTEC) from the Global Positioning System (GPS) observations measurement. The propagation of the LSTID signatures in the GPS TEC measurements over Peninsular Malaysia was also investigated using VTEC map. The LSTIDs were found to propagate both equatorward and poleward directions during these two events. The results showed that the LSTIDs propagated faster at high-latitude region with an average phase velocity of 1074.91 m/s than Peninsular Malaysia with an average phase velocity of 604.84 m/s. The LSTIDs at the high-latitude region have average periods of 150 min whereas the ones observed over Peninsular Malaysia have average periods of 115 min. The occurrences of these LSTIDs were also found to be the subsequent effects of substorm activities in the auroral region. To our knowledge, this is the first result of observation of LSTIDs over Peninsular Malaysia during the 24th solar cycle.

(Chemistry of the global atmosphere)

Energy Technology Data Exchange (ETDEWEB)

Marland, G.

1990-09-27

The traveler attended the conference The Chemistry of the Global Atmosphere,'' and presented a paper on the anthropogenic emission of carbon dioxide (CO{sub 2}) to the atmosphere. The conference included meetings of the International Global Atmospheric Chemistry (IGAC) programme, a core project of the International Geosphere/Biosphere Programme (IGBP) and the traveler participated in meetings on the IGAC project Development of Global Emissions Inventories'' and agreed to coordinate the working group on CO{sub 2}. Papers presented at the conference focused on the latest developments in analytical methods, modeling and understanding of atmospheric CO{sub 2}, CO, CH{sub 4}, N{sub 2}O, SO{sub 2}, NO{sub x}, NMHCs, CFCs, and aerosols.

Does aviation destroy the atmosphere. Experts' discussion on the climate effects of air travel. Zerstoeren Flugzeuge die Atmosphaere. Experten-Duell um die klimatischen Folgen des weltweit zunehmenden Luftverkehrs

Energy Technology Data Exchange (ETDEWEB)

Grassl, H; Walle, F; Hess, W; Reye, B

1994-12-01

According to climate expert Prof. Hartmut Grassl, air travel causes increasing pollution problems in the atmosphere. Dr. Frank Walle, ecology expert of Lufthansa, does not see eye to eye with this. (orig.)

Particle tracking for unsaturated-zone groundwater travel time analysis at Yucca Mountain

International Nuclear Information System (INIS)

Arnold, B.W.; Skinner, L.H.; Zieman, N.B.

1995-01-01

A particle tracking code developed to link numerical modeling of groundwater flow in the unsaturated zone to the analysis of groundwater travel times was used to produce preliminary estimates of the distribution of groundwater-travel time from a potential repository at Yucca Mountain, Nevada to the water table. Compliance with 10CFR960 requires the demonstration that pre-waste-emplacement groundwater travel time from the disturbed zone to the accessible environment is expected to exceed 1,000 years along any path of likely and significant radionuclide travel. The use of multiple particles and multiple realizations of the geology and parameter distributions in the unsaturated zone allows a probabilistic analysis of groundwater travel times that may be applied for evaluating compliance

Relative amplitude of medium-scale traveling ionospheric disturbances as deduced from global GPS network

Science.gov (United States)

Voeykov, S. V.; Afraimovich, E. L.; Kosogorov, E. A.; Perevalova, N. P.; Zhivetiev, I. V.

We worked out a new method for estimation of relative amplitude dI I of total electron content TEC variations corresponding to medium-scale 30-300 km traveling ionospheric disturbances MS TIDs Daily and latitudinal dependences of dI I and dI I probability distributions are obtained for 52 days of 1999-2005 with different level of geomagnetic activity Statistical estimations were obtained for the analysis of 10 6 series of TEC with 2 3-hour duration To obtain statistically significant results three latitudinal regions were chosen North America high-latitudinal region 50-80 r N 200-300 r E 59 GPS receivers North America mid-latitudinal region 20-50 r N 200-300 r E 817 receivers equatorial belt -20 20 r N 0-360 r E 76 receivers We found that average daily value of the relative amplitude of TEC variations dI I changes from 0 3 to 10 proportionally to the value of geomagnetic index Kp This dependence is strong at high latitudes dI I 0 37 cdot Kp 1 5 and it is some weaker at mid latitudes dI I 0 2 cdot Kp 0 35 At the equator belt we found the weakest dependence dI I on the geomagnetic activity level dI I 0 1 cdot Kp 0 6 The most important and the most interesting result of our work is that during geomagnetic quiet conditions the relative amplitude of TEC variations at night considerably exceeds daily values by 3-5 times at equatorial and at high latitudes and by 2 times at mid latitudes But during strong magnetic storms the relative amplitude dI I at high

Designing Affective Atmospheres on the Move

DEFF Research Database (Denmark)

Wind, Simon; Lanng, Ditte Bendix

travelling “unfolds affects as much as reasons” (Jensen, 2013, p.99). Practices, embodiment, technologies and materialities interconnect in non-quantifiable experiences of mobilities, which may fruitfully be unfolded by means of the concept of “atmosphere”. According to Böhme, atmosphere cannot be reduced...... to properties or qualities of neither human nor non-human bodies but they are “manifestations of the co-presence of subject and object” (Böhme, 1998, p.114). When travelling in and through spaces of mobilities in everyday life we are co-constituents in an on-flow of aesthetic atmospheres shaping emotional...... an analytical tool for capturing atmospheres as well as an interventionist tool for orchestrating atmospheres in everyday urban spaces of mobilities. References Anderson, B. (2009) ´Affective Atmospheres´, in: Emotion, Space and Society, pp. 77–81 Bissel, D. (2010) ´Passenger mobilities: affective atmospheres...

Experimental study of the propgation and dispersion of internal atmospheric gravity waves

International Nuclear Information System (INIS)

Ballard, K.A.

1981-01-01

Traveling ionospheric disturbances (TID's) appear as large-scale transverse waves in the F-region (150 to 1000 km altitude), with frequencies on the order of 0.005 to 0.005 cycles per minute, which propagate horizontally over hundreds or even thousands of kilometers. These disturbances have been observed by various radiowave techniques over the past thirty-five years and are now generally accepted as being the manifestation, in the ionized medium, of internal atmospheric gravity waves. A model describing the propagation of gravity waves in an isothermal atmosphere is presented here. The dispersion relation is derived from fundamental principles, and the relation between phase velocity and group velocity is examined. The effects of the Coriolis force and horizontally stratified winds on wave propagation are also analyzed. Conservation of energy in the gravity wave requires increasing amplitude with increasing altitude, inasmuch as the atmospheric density decreases with height. However, this is counteracted by dissipation of wave energy by ion drag, thermal conductivity, and viscous damping. The production of TID's (in the ionized medium) by gravity waves (in the neutral medium) is discussed in quantitative terms, and the vertical predictive function is derived. Dartmouth College has operated a three-station ionosonde network in northern New Hampshire and Vermont on an intermittent basis since 1968. Seven large TID's, found in the 1969 data, are reexamined here in an exhaustive and successful comparison with the gravity wave model. Iso-true-height contours of electron density are used to determine several pertinent TID wave parameters as a function of height

Alaska Tundra Travel Modeling Project and implications for seismic best management practices

Energy Technology Data Exchange (ETDEWEB)

Schultz, G. [Alaska Dept. of Natural Resources, Anchorage, AK (United States)

2007-07-01

Much of the oil and gas exploration in the Alaskan North Slope depends on winter off-road travel to gain access to remote exploration areas. A study was conducted to relate vehicular off-road travel to tundra disturbance. Four types of vehicles were driven on the tundra on specific plots at various times throughout early to mid winter in an effort to determine if travel could occur earlier than current practice without impacting tundra integrity. Variables were measured the summer before travel, at the time of travel and the summers following travel. The results were used to develop a management tool to determine when conditions are adequate to allow winter vehicular off-road travel. It was determined that the soil temperature should be 5 degrees C or colder at a depth of 30 cm, with snow depths of 15 cm in coastal sedge tundra or 23 cm in foothills tussock tundra. This presentation also discussed the implications for managing off-road travel associated with seismic operations and recent changes in the types of vehicles used for these operations. figs.

Prophylaxis of travel-related thrombosis in women.

Science.gov (United States)

Brenner, Benjamin

2009-01-01

Travel-related thrombosis occurs in 1/6,000 individuals who fly long-haul flights. The risk is increased significantly in passengers with thrombophilia and during hormonal therapy. Pregnancy is a hypercoagulable state with 5-10-fold increase in VTE risk. Mechanisms for hypercoagulation on air are related to cabin atmospheric conditions, with immobility and flight duration playing a major role. Prophylactic measures include frequent exercise in all passengers, elastic stockings and LMWH in travelers at high risk.

How does it feel to travel through a tunnel?

DEFF Research Database (Denmark)

Lanng, Ditte Bendix

2014-01-01

of approaching this potential, it is argued, is to work with transit spaces as atmospheric spaces of wayfaring, drawing to the forefront of design considerations the affective engagement between travellers and the material environment. Inherent in this proposition is a critique of the assumptions that daily life...... travelling can be reduced to a desensitized and passive transport practice and that transit spaces are placeless.......This paper opens a pathway for a constructive vision of atmospheric qualities of transit space design. It focuses on an ordinary tunnel for pedestrians and cyclists in a suburban district of Aalborg, Denmark. By way of functionalist design and traffic segregation the tunnel facilitates the passage...

Alaska North Slope Tundra Travel Model and Validation Study

Energy Technology Data Exchange (ETDEWEB)

Harry R. Bader; Jacynthe Guimond

2006-03-01

The Alaska Department of Natural Resources (DNR), Division of Mining, Land, and Water manages cross-country travel, typically associated with hydrocarbon exploration and development, on Alaska's arctic North Slope. This project is intended to provide natural resource managers with objective, quantitative data to assist decision making regarding opening of the tundra to cross-country travel. DNR designed standardized, controlled field trials, with baseline data, to investigate the relationships present between winter exploration vehicle treatments and the independent variables of ground hardness, snow depth, and snow slab thickness, as they relate to the dependent variables of active layer depth, soil moisture, and photosynthetically active radiation (a proxy for plant disturbance). Changes in the dependent variables were used as indicators of tundra disturbance. Two main tundra community types were studied: Coastal Plain (wet graminoid/moist sedge shrub) and Foothills (tussock). DNR constructed four models to address physical soil properties: two models for each main community type, one predicting change in depth of active layer and a second predicting change in soil moisture. DNR also investigated the limited potential management utility in using soil temperature, the amount of photosynthetically active radiation (PAR) absorbed by plants, and changes in microphotography as tools for the identification of disturbance in the field. DNR operated under the assumption that changes in the abiotic factors of active layer depth and soil moisture drive alteration in tundra vegetation structure and composition. Statistically significant differences in depth of active layer, soil moisture at a 15 cm depth, soil temperature at a 15 cm depth, and the absorption of photosynthetically active radiation were found among treatment cells and among treatment types. The models were unable to thoroughly investigate the interacting role between snow depth and disturbance due to a

Study of medium-scale traveling ionospheric disturbances (MSTID) with sounding rockets and ground observations

Science.gov (United States)

Yamamoto, Mamoru; Abe, Takumi; Kumamoto, Atsushi; Yokoyama, Tatsuhiro; Bernhardt, Paul; Watanabe, Shigeto; Yamamoto, Masa-yuki; Larsen, Miguel; Saito, Susumu; Tsugawa, Takuya; Ishisaka, Keigo; Iwagami, Naomoto; Nishioka, Michi; Kato, Tomohiro; Takahashi, Takao; Tanaka, Makoto; Mr

Medium-scale traveling ionospheric disturbance (MSTID) is an interesting phenomenon in the F-region. The MSTID is frequent in summer nighttime over Japan, showing wave structures with wavelengths of 100-200 km, periodicity of about 1 hour, and propagation toward the southwest. The phenomena are observed by the total electron content (TEC) from GEONET, Japanese dense network of GPS receivers, and 630 nm airglow imagers as horizontal pattern. It was also measured as Spread-F events of ionograms or as field-aligned echoes of the MU radar. MSTID was, in the past, explained by Perkins instability (Perkins, 1973) while its low growth rate was a problem. Recently 3D simulation study by Yokoyama et al (2009) hypothesized a generation mechanism of the MSTID, which stands on electromagnetic E/F-region coupling of the ionosphere. The hypothesis is that the MSTID first grows with polarization electric fields from sporadic-E, then show spatial structures resembling to the Perkins instability. We recently conducted a observation campaign to check this hypothesis. We launched JASA ISAS sounding rockets S-310-42 and S-520-27 at 23:00 JST and 23:57JST on July 20, 2013 while an MSTID event was monitored in real-time by the GPS-TEC from GEONET. We found 1-5mV/m northeastward/eastward electric fields during the flight. Variation of electric fileds were associated with horizontal distribution of plasma density. Wind velocity was measured by the TME and Lithium releases from S-310-42 and S-520-27 rockets, respectively, showing southward wind near the sporadic-E layer heights. These results are consistent to the expected generation mechanism shown above. In the presentation we will discuss electric-field results and its relationship with plasma density variability together with preliminary results from the neutral-wind observations.

Traveling waves in a magnetized Taylor-Couette flow

International Nuclear Information System (INIS)

Liu Wei; Ji Hantao; Goodman, Jeremy

2007-01-01

We investigate numerically a traveling wave pattern observed in experimental magnetized Taylor-Couette flow at low magnetic Reynolds number. By accurately modeling viscous and magnetic boundaries in all directions, we reproduce the experimentally measured wave patterns and their amplitudes. Contrary to previous claims, the waves are shown to be transiently amplified disturbances launched by viscous boundary layers, rather than globally unstable magnetorotational modes

PTRACK: A particle tracking program for evaluation travel path/travel time uncertainties

International Nuclear Information System (INIS)

Thompson, B.M.; Campbell, J.E.; Longsine, D.E.

1987-12-01

PTRACK is a model which tracks the path of a radionuclide particle released from a nuclear waste repository into a ground-water flow system in a two-dimensional representation of stratified geologic medium. The code calculates the time required for the particle to travel from the release point (the edge of the disturbed zone) to the specified horizontal or vertical boundary (the accessible environment). The physical properties of the geologic setting and the ground-water flow system can be treated as fixed values or as random variables sampled from their respective probability distributions. In the latter case, PTRACK assigns a sampled value for each parameter and tracks a particle for this trial (realization) of the system. Repeated realizations allow the effects of parameter uncertainty on travel paths/travel times to be quantified. The code can also calculate partial correlation coefficients between dependent variables and independent variables, which are useful in identifying important independent variables. This documentation describes the mathematical basis for the model, the algorithms and solution techniques used, and the computer code design. It also contains a detailed user's manual. The implementation of PTRACK is verified with several systems for which solutions have been calculated by hand. The integration of PTRACK with a Latin hypercube sampling (LHS) code is also discussed, although other sampling methods can be employed in place of LHS. 11 refs., 14 figs., 22 tabs

Natural disturbance impacts on Canada's forest carbon budget

International Nuclear Information System (INIS)

Kurz, W.

2004-01-01

Wildfire and insect outbreaks are major determinants of forest dynamics in Canada, transferring carbon within the ecosystem, releasing carbon into the atmosphere and influencing post-disturbance carbon dynamics. This paper discusses the impacts of global climate change on natural disturbances. Higher temperatures and drier conditions are likely to increase burned areas in Canada and will also increase the impacts of insects, allowing for an expanded range and stressing their host species. Long-term changes in disturbance regimes have already affected Canada's forest age-class structure. Statistics of lower disturbance periods and carbon production were compared with periods of higher disturbance. Scenario analyses were conducted for the period of 1996 to 2032, assuming that annual insect and fire disturbance rates in timber-productive forests were 20 per cent higher and carbon production 20 per cent lower than base scenarios using average disturbance rates. It was concluded that these conditions could cause carbon stocks in Canada's forests to decline. The future carbon balance of Canada's forests will be affected by the rate of natural and human-induced disturbances. 4 refs

Solar-terrestrial disturbances of June-September 1982, 4

International Nuclear Information System (INIS)

Minakoshi, Hisamitsu; Sinno, Kenji; Nishimuta, Ichizo

1986-01-01

The ionospheric disturbances observed in and around Japan in association with the severe geomagnetic storm occurring on July 14 - 16, 1982 were investigated by using ionospheric total electron content (N t ) data obtained by the ETS-II beacon experiment and F region data obtained by the soundings at the latitude chain of the ionospheric stations situated nearly along 135 deg E. The most remarkable storm effect was of the negative disturbance, which is common at mid-latitudes in summer. The negative disturbance comprises the decreases in N t and peak electron density (N m ) and a marked increase in slab thickness. In addition, the following interesting events were observed during this storm: (1) sharp depressions in N t and N m occurred almost simultaneously in the regions from mid-latitudes to the equatorial latitude within a few hours after the storm sudden commencement (SSC), (2) some positive disturbances in the F region appeared during the recovery phase of the storm, and were prominent during the night at mid-latitudes and during the daytime at low latitudes, and (3) wavelike fluctuations of N t , which indicate the existence of a mediumscale traveling ionospheric disturbance (TID) with a nearly north to south direction of propagation, were observed during the main phase. (author)

Atmosphere-ionosphere coupling from convectively generated gravity waves

Science.gov (United States)

Azeem, Irfan; Barlage, Michael

2018-04-01

Ionospheric variability impacts operational performances of a variety of technological systems, such as HF communication, Global Positioning System (GPS) navigation, and radar surveillance. The ionosphere is not only perturbed by geomagnetic inputs but is also influenced by atmospheric tides and other wave disturbances propagating from the troposphere to high altitudes. Atmospheric Gravity Waves (AGWs) excited by meteorological sources are one of the largest sources of mesoscale variability in the ionosphere. In this paper, Total Electron Content (TEC) data from networks of GPS receivers in the United States are analyzed to investigate AGWs in the ionosphere generated by convective thunderstorms. Two case studies of convectively generated gravity waves are presented. On April 4, 2014 two distinct large convective systems in Texas and Arkansas generated two sets of concentric AGWs that were observed in the ionosphere as Traveling Ionospheric Disturbances (TIDs). The period of the observed TIDs was 20.8 min, the horizontal wavelength was 182.4 km, and the horizontal phase speed was 146.4 m/s. The second case study shows TIDs generated from an extended squall line on December 23, 2015 stretching from the Gulf of Mexico to the Great Lakes in North America. Unlike the concentric wave features seen in the first case study, the extended squall line generated TIDs, which exhibited almost plane-parallel phase fronts. The TID period was 20.1 min, its horizontal wavelength was 209.6 km, and the horizontal phase speed was 180.1 m/s. The AGWs generated by both of these meteorological events have large vertical wavelength (>100 km), which are larger than the F2 layer thickness, thus allowing them to be discernible in the TEC dataset.

Solar-terrestrial disturbances of June-September 1982, 4

International Nuclear Information System (INIS)

Minakoshi, Hisamitsu; Sinno, Kenji; Nishimuta, Ichizo

1985-01-01

The ionospheric disturbances around Japan associated with the severe magnetic storm on July 14-16, 1982 were investigated using ionospheric total electron content (Nsub(t)) data obtained by the ETS-II beacon experiment and F-region data obtained by the soundings at the latitude chain of the ionospheric stations situated nearly along 135 0 E. The most remarkable storm effects were the negative disturbances, which are common at mid-latitudes in summer. The negative disturbances comprise decreases in Nsub(t) and peak electron density (Nsub(m)) and a marked increase in slab thickness. In addition, the following interesting events were observed during this storm: (1) sharp decreases in Nsub(t) and Nsub(m) occurred almost simultaneously in the regions from mid-latitudes to the equatorial latitude within a few hours after the storm sudden commencement (SSC), (2) some positive disturbances in the F-region appeared during the last phase of the storm, which were prominent at mid-latitudes during the night and at low-latitudes in the afternoon, and (3) a medium-scale traveling ionospheric distubance (TID) with a nearly north to south direction of propagation was observed as wavelike fluctuations of Nsub(t). (author)

Pilot ionosonde network for identification of traveling ionospheric disturbances

Czech Academy of Sciences Publication Activity Database

Reinisch, B.; Galkin, I.; Belehaki, A.; Paznukhov, V.; Huang, X.; Altadill, D.; Burešová, Dalia; Mielich, J.; Verhulst, T.; Stankov, S.; Blanch, E.; Kouba, Daniel; Hamel, R.; Kozlov, A.; Tsagouri, I.; Mouzakis, A.; Messerotti, M.; Parkinson, M.; Ishii, M.

2018-01-01

Roč. 53, č. 3 (2018), s. 365-378 R&D Projects: GA ČR(CZ) GAP209/12/2440 EU Projects: European Commission 776011 - TechTIDE Institutional support: RVO:68378289 Subject RIV: DG - Athmosphere Sciences, Meteorology OBOR OECD: Meteorology and atmospheric sciences http://onlinelibrary.wiley.com/doi/10.1002/2017RS006263/epdf

Non-Equilibrium Radiative Transfer in Structured Atmospheres

National Research Council Canada - National Science Library

Picard, R. H; Winick, J. R; Wintersteiner, P. P

2002-01-01

... passage of both atmospheric gravity waves and transient frontal disturbances or bores. The infrared emissions from this part of the atmosphere are already typically not in local thermodynamic equilibrium (LTE...

Intensive ground vegetation growth mitigates the carbon loss after forest disturbance.

Science.gov (United States)

Zehetgruber, Bernhard; Kobler, Johannes; Dirnböck, Thomas; Jandl, Robert; Seidl, Rupert; Schindlbacher, Andreas

2017-01-01

Slow or failed tree regeneration after forest disturbance is increasingly observed in the central European Alps, potentially amplifying the carbon (C) loss from disturbance. We aimed at quantifying C dynamics of a poorly regenerating disturbance site with a special focus on the role of non-woody ground vegetation. Soil CO 2 efflux, fine root biomass, ground vegetation biomass, tree increment and litter input were assessed in (i) an undisturbed section of a ~ 110 years old Norway spruce stand, (ii) in a disturbed section which was clear-cut six years ago (no tree regeneration), and (iii) in a disturbed section which was clear-cut three years ago (no tree regeneration). Total soil CO 2 efflux was similar across all stand sections (8.5 ± 0.2 to 8.9 ± 0.3 t C ha -1  yr. -1 ). The undisturbed forest served as atmospheric C sink (2.1 t C ha -1  yr. -1 ), whereas both clearings were C sources to the atmosphere. The source strength three years after disturbance (-5.5 t C ha -1  yr. -1 ) was almost twice as high as six years after disturbance (-2.9 t C ha -1  yr. -1 ), with declining heterotrophic soil respiration and the high productivity of dense graminoid ground vegetation mitigating C loss. C loss after disturbance decreases with time and ground vegetation growth. Dense non-woody ground vegetation cover can hamper tree regeneration but simultaneously decrease the ecosystem C loss. The role of ground vegetation should be more explicitly taken into account in forest C budgets assessing disturbance effects.

Real-time travel time prediction framework for departure time and route advice

NARCIS (Netherlands)

Calvert, S.C.; Snelder, M.; Bakri, T.; Heijligers, B.; Knoop, V.L.

2015-01-01

Heavily used urban networks remain a challenge for travel time prediction because traffic flow is rarely homogeneous and is also subject to a wide variety of disturbances. Various models, some of which use traffic flow theory and some of which are data driven, have been developed to predict traffic

Thermally-Induced Structural Disturbances of Rigid Panel Solar Arrays

Science.gov (United States)

Johnston, John D.; Thornton, Earl A.

1997-01-01

The performance of a significant number of spacecraft has been impacted negatively by attitude disturbances resulting from thermally-induced motions of flexible structures. Recent examples of spacecraft affected by these disturbances include the Hubble Space Telescope (HST) and the Upper Atmosphere Research Satellite (UARS). Thermally-induced structural disturbances occur as the result of rapid changes in thermal loading typically initiated as a satellite exits or enters the Earth's shadow. Temperature differences in flexible appendages give rise to structural deformations, which in turn result in disturbance torques reacting back on the spacecraft. Structures which have proven susceptible to these disturbances include deployable booms and solar arrays. This paper investigates disturbances resulting from thermally-induced deformations of rigid panel solar arrays. An analytical model for the thermal-structural response of the solar array and the corresponding disturbance torque are presented. The effect of these disturbances on the attitude dynamics of a simple spacecraft is then investigated using a coupled system of governing equations which includes the effects of thermally-induced deformations. Numerical results demonstrate the effect of varying solar array geometry on the dynamic response of the system.

Observational Study of Travelers' Diarrhea.

Science.gov (United States)

Meuris

1995-03-01

Background: European air travelers returning from Algeria, Egypt, Mexico, Morocco, and Tunisia were interviewed about their experience of travelers' diseases upon arrival in Brussels. Diarrhea was mentioned by 37% of the adults and 27% of the children. These subjects were questioned about the types of measures taken, type and duration of drug treatment (if any), and about duration of diarrhea and side effects experienced. Methods: Final analysis was performed based on 2160 interviews. The largest proportion of diarrhea was reported in the age group 15-24 years (46%). Results: The majority of the 2160 subjects had opted for drug treatment (81%): 927 subjects for loperamide alone, 235 for loperamide in combination with nifuroxazide, and 178 for nifuroxazide alone. Other drugs had been used less frequently. The median time to recovery was 2.4 days with loperamide compared to 3.2 days with nifuroxazide and to 3.4 days for the no-treatment group. Conclusions: A stratification of the results by severity of the diarrhea suggests a rank of antidiarrheal potency as follows: loperamide > nifuroxazide > no-drug treatment. The side effect with the highest incidence was constipation (2.4% with loperamide). (J Travel Med 2:11-15, 1995) Travelers' diarrhea is usually defined as the passage of at least three unformed stools per day or any number of such stools when accompanied by fever, abdominal cramping, or vomiting. The definition may be broadened to include more trivial bowel disturbance.1,2 The duration of this self-limited disease generally is 3 to 5 days. Medical intervention aims at shortening the duration of disease, thus allowing the sufferer to resume his or her usual activities at an early stage. A shortened period of recovery to physical well-being has obvious favorable economic implications if the traveler is on business and may help the maintenance of a desired level of quality of life while a traveler is on holiday. An observational study of various medical

Evaluation of the uncertainty in the azimuth calculation for the detection and localization of atmospheric nuclear explosions

International Nuclear Information System (INIS)

Schuff, J.A.

2006-01-01

Low-frequency acoustic signal below about 1 Hz can travel for hundreds or thousands of kilometers through in the Earth atmosphere. If a source produces infrasonic energy, it can be detected by a remote sensor. Atmospheric strong explosions as the nuclear detonation contains low-frequency components that can travel long distances with measurable signal levels. This fact can be useful for detection and localization of clandestine events. The international regime on the non-proliferation of nuclear requires the ability to detect, localize, and discriminate nuclear events on a global scale. Monitoring systems such as the Inter national Monitoring System (I.M.S.) rely on several sensor technologies to perform these functions. The current I.M.S. infra sound system design includes a network of low-frequency atmospheric acoustic sensor arrays, which contribute primarily to the detection and localization of atmospheric nuclear events. There have been observed differences between the azimuth measurements and the true directions of the sources of infra sound waves in artificial and natural events such as explosive eruptions of strong volcanoes. The infra sound waves are reflected in stratospheric and thermospheric layers near 50 km and 120 km in height respectively. The azimuth deviation is affected by meteorological disturbances in the troposphere and stratosphere. This paper describe new elements to obtain the uncertainty in the azimuth calculation of arrival wave plane passing across of a not plane array of infra sound sensors. It also presents a 3D computation of infra sound propagation and estimation of the azimuth deviation using the zonal horizontal wind model and M.S.I.S.E.-90 model of the upper atmosphere to obtain temperature, density and concentration of the principal components of the air for altitudes of up to 120 km. Deviations of up to 12 degrees in the azimuth were obtained, depending on the location of the source of infra sound, the point of measurement and

Numerical Simulation of Ionospheric Disturbances Generated by the Chelyabinsk and Tunguska Space Body Impacts

Science.gov (United States)

Shuvalov, V. V.; Khazins, V. M.

2018-03-01

Numerical simulation of atmospheric disturbances during the first hours after the Chelyabinsk and Tunguska space body impacts has been carried out. The results of detailed calculations, including the stages of destruction, evaporation and deceleration of the cosmic body, the generation of atmospheric disturbances and their propagation over distances of thousands of kilometers, have been compared with the results of spherical explosions with energy equal to the kinetic energy of meteoroids. It has been shown that in the case of the Chelyabinsk meteorite, an explosive analogy provides acceptable dimensions of the perturbed region and the perturbation amplitude. With a more powerful Tunguska fall, the resulting atmospheric flow is very different from the explosive one; an atmospheric plume emerges that releases matter from the meteoric trace to an altitude of the order of a thousand kilometers.

Features of infrasonic and ionospheric disturbances generated by launch vehicle

International Nuclear Information System (INIS)

Drobzheva, Ya.V.; Krasnov, V.M.; Sokolova, O.I.

2001-01-01

In this paper we present a model, which describe the propagation of acoustic pulses through a model terrestrial atmosphere produced by launch vehicle, and effects of these pulses on the ionosphere above the launch vehicle. We show that acoustic pulses generate disturbances of electron density. The value of these disturbances is about 0.04-0.7% of background electron density. So such disturbances can not create serious noise-free during monitoring of explosions by ionospheric method. We calculated parameters of the blast wave generated at the ionospheric heights by launch vehicle. It was shown that the blast wave is intense and it can generates disturbance of electron density which 2.6 times as much then background electron density. This disturbance is 'cord' with diameter about 150-250 m whereas length of radio line is hundreds and thousand km. Duration of ionospheric disturbances are from 0.2 s to 3-5 s. Such values of duration can not be observed during underground and surface explosions. (author)

Travel Health Advisory Group: a joint travel industry and travel health Special Interest Group promoting healthy travel in Australia.

Science.gov (United States)

Leggat, Peter A; Zwar, Nicholas; Hudson, Bernie

2012-09-01

The Travel Health Advisory Group (THAG), established in 1997, is a joint initiative between the travel industry and travel health professionals in Australia that aims to promote healthy travel. THAG seeks to promote cooperation in improving the health of travellers between the travel industry and travel medicine professionals and to raise public awareness of the importance of travel health. From 2011, THAG has been a Special Interest Group of The Australasian College of Tropical Medicine and its membership has been active in several areas, including web-based travel health information, travel health promotion, media releases, research and education in Australia. Information is given on the objectives, membership and an overview of the various activities of the group. Copyright © 2012 Elsevier Ltd. All rights reserved.

Bioethics and transnational medical travel: India,"medical tourism," and the globalisation of healthcare.

Science.gov (United States)

Runnels, Vivien; Turner, Leigh

2011-01-01

Health-related travel, also referred to as "medical tourism" is historically well-known. Its emerging contemporary form suggests the development of a form of globalised for-profit healthcare. Medical tourism to India, the focus of a recent conference in Canada, provides an example of the globalisation of healthcare. By positioning itself as a low-cost, high-tech, fast-access and high-quality healthcare destination country, India offers healthcare to medical travellers who are frustrated with waiting lists and the limited availability of some procedures in Canada. Although patients have the right to travel and seek care at international medical facilities, there are a number of dimensions of medical tourism that are disturbing. The diversion of public investments in healthcare to the private sector, in order to serve medical travellers, perversely transfers public resources to international patients at a time when the Indian public healthcare system fails to provide primary healthcare to its own citizens. Further, little is known about patient safety and quality care in transnational medical travel. Countries that are departure points as well as destination countries need to carefully explore the ethical, social, cultural, and economic consequences of the growing phenomenon of for-profit international medical travel.

Travel-related health problems in Japanese travelers.

Science.gov (United States)

Mizuno, Yasutaka; Kudo, Koichiro

2009-09-01

Although the number of Japanese individuals traveling abroad has increased steadily, reaching approximately 17.3 million in 2007, the incidence of various travel-related health problems in Japan remains unknown. The travel-related health problems of Japanese travelers returning to Japan from abroad are analyzed by assessing the records. Data were collected retrospectively on returning travelers who visited the authors' travel clinic during the period from January 2005 through to December 2006 with any health problem acquired overseas. A total of 345 patients were included in this study (200 male, 145 female; average age, 34+/-12.3 years). Reasons for travel included leisure (45.8%); business (39.1%); visiting friends and relatives or accompanying other travelers (8.7%); volunteering (3.8%); and long stays in order to study or live (2.6%). The most visited destination was Asia (n=260), followed by Africa (n=105). The most commonly reported health problems were gastro-intestinal infections (39.1%), followed by respiratory tract infections (16.2%), animal bites (8.1%), and skin problems (5.8%). Together, malaria and dengue accounted for 10% of diagnoses in 125 febrile patients (36.2%). Although the profile of travel-related health problems in Japanese travelers is similar to that of Western travelers, the characteristics of travel were quite different. Therefore Japanese travel advice should be tailored to suit the Japanese traveler.

Sensitivity of climate mitigation strategies to natural disturbances

International Nuclear Information System (INIS)

Le Page, Y; Hurtt, G; Thomson, A M; Bond-Lamberty, B; Patel, P; Wise, M; Calvin, K; Kyle, P; Clarke, L; Edmonds, J; Janetos, A

2013-01-01

The present and future concentration of atmospheric carbon dioxide depends on both anthropogenic and natural sources and sinks of carbon. Most proposed climate mitigation strategies rely on a progressive transition to carbon-efficient technologies to reduce industrial emissions, substantially supported by policies to maintain or enhance the terrestrial carbon stock in forests and other ecosystems. This strategy may be challenged if terrestrial sequestration capacity is affected by future climate feedbacks, but how and to what extent is little understood. Here, we show that climate mitigation strategies are highly sensitive to future natural disturbance rates (e.g. fires, hurricanes, droughts), because of the potential effect of disturbances on the terrestrial carbon balance. Generally, altered disturbance rates affect the pace of societal and technological transitions required to achieve the mitigation target, with substantial consequences on the energy sector and the global economy. An understanding of the future dynamics and consequences of natural disturbances on terrestrial carbon balance is thus essential for developing robust climate mitigation strategies and policies. (letter)

Investigation of conditions for the generation and propagation of low-frequency disturbances in the troposphere

Science.gov (United States)

Mordvinov, V. I.; Devyatova, E. V.; Kochetkova, O. S.; Oznobikhina, O. A.

2013-01-01

Low-frequency disturbances responsible for the excitation of torsional oscillations—variations in the zonal mean flow intensity with a characteristic scale of 15-20 days—propagating along the meridian at mid and low latitudes of both hemispheres are investigated [1]. As data observed over the eastern parts of continents and the western parts of oceans are processed with the lag correlation statistics, traveling waves intersecting the eastern parts of continents from northwest to southeast and then returning to the north along the ocean coasts are identified. In this case, trains of anomalies oriented in the zonal direction periodically appear and are destructed in the western parts of continents. The simulation of the propagation of disturbances in the quasi-geostrophic approximation made it possible to explain the specific features of lag correlation statistics over continents by the dispersion of two-dimensional Rossby waves from traveling sources. The turnover of disturbances over Asia and wave trains to the west from the pole were reproduced. Torsional oscillations caused by the dispersion of two-dimensional Rossby waves have a characteristic form of inclined bands in the latitude-time diagram, whose steepness is controlled by the velocity of displacement of the vorticity source along the meridian.

Interaction between ionization and gravity waves in the upper atmosphere

International Nuclear Information System (INIS)

Balcioglu, O.

1982-10-01

It is known that travelling ionospheric disturbances are produced by gravity waves. During their movement from the F region downwards to the E region, gravity waves can produce thin layers called transients on ionograms and, if the wave motion persists, 'h-type Esub(S) can be produced. To investigate the problem, the continuity equations for both the E and F regions are solved for a perturbation, the motion of which is taken to be a gravity wave. Hitherto, N'/N 0 , the ratio of the disturbed to the undisturbed electron density, has been calculated by using only the Hall conductivity and ignoring the diffusion term for the F region. In the present calculations we have used Pedersan and Hall conductivities and calculated the N'/N 0 ratio for both the E and F regions. Using CIRA standard atmosphere data we find for the F region that N' can exceed N 0 by up to 4 percent, depending on the horizontal wind velocity. In the E region, N' reaches much higher values than in the F region. Thus at 120 km if we take a typical horizontal wind velocity of 80 m/sec (wavelength 150 km), N' is about twice as large as N 0 . From these results we see that the diffusion term is important for the E region. (author)

Inflatable Indian travel pillow as a pneumatic patient jack

Directory of Open Access Journals (Sweden)

Gopalakrishna A

2006-01-01

Full Text Available The Indian travel pillow readily available in the market has been utilized as a patient jack in the operation theatre. This has been used to raise the shoulders of an anaesthetized patient for surgery in the head and neck region and a set of two pillows have been used to prop-up a prone anaesthetized patient. This allows smooth positioning of the patient after intubation without disturbance to the airway with minimal manpower.

Travel characteristics and health practices among travellers at the travellers' health and vaccination clinic in Singapore.

Science.gov (United States)

Lee, Vernon J; Wilder-Smith, Annelies

2006-10-01

Singapore has a fast-growing travel industry, but few studies have been done on travel characteristics and travel health practices. This study describes the profile and healthseeking behaviour of travellers attending a travel health clinic in Singapore. A cross-sectional survey was conducted on travellers attending the Traveller's Health and Vaccination Centre (THVC) between September and November 2002 using a standardised questionnaire. Information obtained included individual demographic and medical information, travel patterns, vaccination status and travel health practices. Four hundred and ninetyfive (74%) eligible travellers seen at THVC responded to the questionnaire. Their mean age was 36 years; 77% were professionals, managers, executives, and businessmen, students, and white collar workers. Asia was the main travel destination, and most travelled for leisure and resided in hotels or hostels. The median duration of travel was 16 days. Although >90% had previously travelled overseas, only 20% had previously sought pre-travel advice. Malays were significantly underrepresented (P travel advice compared with Chinese, Indians and Malays. Factors associated with seeking pre-travel advice included travel outside of Asia, especially Africa and South America. Singaporean travellers travel more often to cities rather than rural areas, compared with non-Asian travellers. Asia is the preferred destination, and travel outside of Asia is perceived as more risky and is associated with seeking pre-travel advice and vaccinations. Travel patterns and behaviours need to be taken into account when developing evidence-based travel medicine in Asia.

Pre-travel advice seeking from GPs by travellers with chronic illness seen at a travel clinic.

Science.gov (United States)

Gagneux-Brunon, Amandine; Andrillat, Carole; Fouilloux, Pascale; Daoud, Fatiha; Defontaine, Christiane; Charles, Rodolphe; Lucht, Frédéric; Botelho-Nevers, Elisabeth

2016-03-01

Travellers are ageing and frequently report chronic illness. Pre-travel health advice is crucial, particularly in this subgroup, and general practitioners (GPs) are first in line for treatment adjustment before departure. Our aim is to evaluate pre-travel health advice seeking from GPs by travellers with chronic illness seen at a travel clinic. A cross-sectional observational survey using a questionnaire was conducted between August 2013 and July 2014 in travellers attending the travel medicine clinic of a tertiary university hospital in France. During the study, 2019 travellers were included. Mean age was 39.4 years (±18.8). Three hundred and ninety-one (19.4%) travellers reported a history of a chronic illness. Arterial hypertension and diabetes mellitus were the most frequently reported illnesses, affecting, respectively, 168 (8.3%) travellers and 102 (5.1%). Hajj pilgrims were more likely to report a history of chronic illness than other travellers. Only 810 (40.1%) travellers sought pre-travel advice from their GP. Six hundred and fifty-two (40.1%) healthy travellers and 158 (40.5%) travellers reporting chronic illness sought pre-travel advice from their GP (P = 0.96). Travellers with a history of chronic illness do not seek pre-travel health advice from their GP more frequently than healthy travellers. Travel health specialists are generally not the best practitioners to manage the care of underlying medical conditions presenting risks during travel. However, GPs offer continuity and disease management expertise to improve the specificity of pre-travel planning. Thus, ongoing collaboration between the traveller, GP and travel health specialist is likely to yield the best outcomes. © International Society of Travel Medicine, 2016. All rights reserved. Published by Oxford University Press. For permissions, please e-mail: journals.permissions@oup.com.

Atmospheric methods for nuclear test monitoring

International Nuclear Information System (INIS)

Simons, D.J.

1995-01-01

The U.S. DOE sponsored research investigating atmospheric infrasound as a means of detecting both atmospheric and underground nuclear tests. Various detection schemes were examined and were found to be effective for different situations. It has been discovered that an enhanced sensitivity is realizable for the very lowest frequency disturbances by detecting the infrasound at the top of the atmosphere using ratio sound techniques. These techniques are compared to more traditional measurement schemes

Pre-Travel Medical Preparation of Business and Occupational Travelers

Science.gov (United States)

Khan, Nomana M.; Jentes, Emily S.; Brown, Clive; Han, Pauline; Rao, Sowmya R.; Kozarsky, Phyllis; Hagmann, Stefan H.F.; LaRocque, Regina C.; Ryan, Edward T.

2016-01-01

Objectives: The aim of the study was to understand more about pre-travel preparations and itineraries of business and occupational travelers. Methods: De-identified data from 18 Global TravEpiNet clinics from January 2009 to December 2012 were analyzed. Results: Of 23,534 travelers, 61% were non-occupational and 39% occupational. Business travelers were more likely to be men, had short times to departure and shorter trip durations, and commonly refused influenza, meningococcal, and hepatitis B vaccines. Most business travelers indicated that employers suggested the pre-travel health consultation, whereas non-occupational travelers sought consultations because of travel health concerns. Conclusions: Sub-groups of occupational travelers have characteristic profiles, with business travelers being particularly distinct. Employers play a role in encouraging business travelers to seek pre-travel consultations. Such consultations, even if scheduled immediately before travel, can identify vaccination gaps and increase coverage. PMID:26479857

Fair weather atmospheric electricity

International Nuclear Information System (INIS)

Harrison, R G

2011-01-01

Not long after Franklin's iconic studies, an atmospheric electric field was discovered in 'fair weather' regions, well away from thunderstorms. The origin of the fair weather field was sought by Lord Kelvin, through development of electrostatic instrumentation and early data logging techniques, but was ultimately explained through the global circuit model of C.T.R. Wilson. In Wilson's model, charge exchanged by disturbed weather electrifies the ionosphere, and returns via a small vertical current density in fair weather regions. New insights into the relevance of fair weather atmospheric electricity to terrestrial and planetary atmospheres are now emerging. For example, there is a possible role of the global circuit current density in atmospheric processes, such as cloud formation. Beyond natural atmospheric processes, a novel practical application is the use of early atmospheric electrostatic investigations to provide quantitative information on past urban air pollution.

Direct EUV/X-Ray Modulation of the Ionosphere During the August 2017 Total Solar Eclipse

Science.gov (United States)

Mrak, Sebastijan; Semeter, Joshua; Drob, Douglas; Huba, J. D.

2018-05-01

The great American total solar eclipse of 21 August 2017 offered a fortuitous opportunity to study the response of the atmosphere and ionosphere using a myriad of ground instruments. We have used the network of U.S. Global Positioning System receivers to examine perturbations in maps of ionospheric total electron content (TEC). Coherent large-scale variations in TEC have been interpreted by others as gravity wave-induced traveling ionospheric disturbances. However, the solar disk had two active regions at that time, one near the center of the disk and one at the edge, which resulted in an irregular illumination pattern in the extreme ultraviolet (EUV)/X-ray bands. Using detailed EUV occultation maps calculated from the National Aeronautics and Space Administration Solar Dynamics Observatory Atmospheric Imaging Assembly images, we show excellent agreement between TEC perturbations and computed gradients in EUV illumination. The results strongly suggest that prominent large-scale TEC disturbances were consequences of direct EUV modulation, rather than gravity wave-induced traveling ionospheric disturbances.

Travel medicine

Science.gov (United States)

Aw, Brian; Boraston, Suni; Botten, David; Cherniwchan, Darin; Fazal, Hyder; Kelton, Timothy; Libman, Michael; Saldanha, Colin; Scappatura, Philip; Stowe, Brian

2014-01-01

Abstract Objective To define the practice of travel medicine, provide the basics of a comprehensive pretravel consultation for international travelers, and assist in identifying patients who might require referral to travel medicine professionals. Sources of information Guidelines and recommendations on travel medicine and travel-related illnesses by national and international travel health authorities were reviewed. MEDLINE and EMBASE searches for related literature were also performed. Main message Travel medicine is a highly dynamic specialty that focuses on pretravel preventive care. A comprehensive risk assessment for each individual traveler is essential in order to accurately evaluate traveler-, itinerary-, and destination-specific risks, and to advise on the most appropriate risk management interventions to promote health and prevent adverse health outcomes during travel. Vaccinations might also be required and should be personalized according to the individual traveler’s immunization history, travel itinerary, and the amount of time available before departure. Conclusion A traveler’s health and safety depends on a practitioner’s level of expertise in providing pretravel counseling and vaccinations, if required. Those who advise travelers are encouraged to be aware of the extent of this responsibility and to refer all high-risk travelers to travel medicine professionals whenever possible. PMID:25500599

Acoustic tomography in the atmospheric surface layer

Directory of Open Access Journals (Sweden)

A. Ziemann

Full Text Available Acoustic tomography is presented as a technique for remote monitoring of meteorological quantities. This method and a special algorithm of analysis can directly produce area-averaged values of meteorological parameters. As a result consistent data will be obtained for validation of numerical atmospheric micro-scale models. Such a measuring system can complement conventional point measurements over different surfaces. The procedure of acoustic tomography uses the horizontal propagation of sound waves in the atmospheric surface layer. Therefore, to provide a general overview of sound propagation under various atmospheric conditions a two-dimensional ray-tracing model according to a modified version of Snell's law is used. The state of the crossed atmosphere can be estimated from measurements of acoustic travel time between sources and receivers at different points. Derivation of area-averaged values of the sound speed and furthermore of air temperature results from the inversion of travel time values for all acoustic paths. Thereby, the applied straight ray two-dimensional tomographic model using SIRT (simultaneous iterative reconstruction technique is characterised as a method with small computational requirements, satisfactory convergence and stability properties as well as simple handling, especially, during online evaluation.

Key words. Meteorology and atmospheric dynamics (turbulence; instruments and techniques.

Numerical modelling of the structure of electromagnetic disturbances generated by acoustic-gravity waves

International Nuclear Information System (INIS)

Pogorel'tsev, A.I.; Bidlingmajer, E.R.

1992-01-01

A numeric model of electromagnetic field disturbances generated under the interaction of acoustic-gravitational waves with ionospheric plasma is elaborated and vertical structure of the above disturbances is calculated. The estimates shown that electromagnetic disturbances can penetrate into neutral atmosphere and can be recorded through measurements of the variation of magnetic field and electron field vertical component near the earth is surface. A conclusion is made on a feasibility of monitoring of acoustic-gravitational wave activity in the lower thermosphere through land measurements of magnetic and electric field variations

Disturbance Driven Rainfall in O`ahu, Hawai`i (1990-2010)

Science.gov (United States)

Longman, R. J.; Elison Timm, O.; Giambelluca, T. W.; Kaiser, L.; Newman, A. J.; Arnold, J.; Clark, M. P.

2017-12-01

Trade wind orographic rainfall is the most prevalent synoptic weather pattern in Hawai`i and provides a year-round source of moisture to the windward areas across the Island chain. Significant contributions to total and extreme precipitation have also been linked to one of four atmospheric disturbance situations that include: cold fronts, Kona storms, upper-tropospheric disturbances (upper level lows), and tropical systems. The primary objective of this research is to determine how these disturbance types contribute to total wet-season rainfall (RF) on the Island of O`ahu, Hawai`i and to identify any significant changes in the frequency of occurrence and or the intensity of these events. Atmospheric fronts that occurred in the Hawai`i region (17-26°N, 150-165°W) were extracted from a global dataset and combined with a Kona low and upper level low dataset to create a daily categorical weather classification time series (1990-2010). Mean rainfall was extracted from gridded daily O`ahu RF maps. Results show that the difference between a wet and dry year is predominantly explained by the RF contributions from disturbance events (r2 = 0.57, p cold fronts that cross the Island. During the wettest season on record, disturbances accounted for 48% of the total RF, while during the driest season they accounted for only 6% of the total RF. The event-based RF analysis also compared the RF intensity in the absence of disturbance events with the average RF intensity on days when atmospheric fronts are present but do not cross the island. The results show that non-crossing fronts reduce the average RF intensity. A possible explanation is that these events are too far away to produce RF, but close enough to disrupt normal trade wind flow, thus limiting orographic RF on the island. This new event-based RF analysis has important implications for the projection of regional climate change in Hawai`i. Our results suggest that if storm tracks were to shift poleward, O`ahu wet season

International business travel: impact on families and travellers.

Science.gov (United States)

Espino, C M; Sundstrom, S M; Frick, H L; Jacobs, M; Peters, M

2002-05-01

Spouses and staff of the World Bank Group (WBG) were questioned about the impact of international business travel on families and travellers. Dependent variables were self reported stress, concern about the health of the traveller, and negative impact on the family. We hypothesised that several travel factors (independent variables) would be associated with these impacts. These travel factors had to do with the frequency, duration, and predictability of travel and its interference with family activities. Survey forms were developed and distributed to all spouses of travelling staff as well as a small sample of operational staff. Kendall's tau b correlation coefficients of response frequencies were computed with the data from scaled items. Written responses to open ended questions were categorised. Response rates for spouses and staff were 24% and 36%, respectively. Half the spouse sample (n=533) and almost 75% of the staff sample (n=102) reported high or very high stress due to business travel. Self reported spouse stress was associated with six out of eight travel factors. Female spouses, those with children, and younger spouses reported greater stress. Self reported staff stress was significantly associated with four out of nine travel factors. Further insight into how business travel affects families and staff (including children's behavioural changes) and how families cope was gained through responses to written questions. The findings support the notion that lengthy and frequent travel and frequent changes in travel dates which affect family plans, all characteristic of WBG missions, negatively affects many spouses and children (particularly young children) and that the strain on families contributes significantly to the stress staff feel about their travel. Policies or management practices that take into consideration family activities and give staff greater leeway in controlling and refusing travel may help relieve stress.

Propagating Disturbances in Coronal Loops: A Detailed Analysis of Propagation Speeds

Science.gov (United States)

Kiddie, G.; De Moortel, I.; Del Zanna, G.; McIntosh, S. W.; Whittaker, I.

2012-08-01

Quasi-periodic disturbances have been observed in the outer solar atmosphere for many years. Although first interpreted as upflows (Schrijver et al., Solar Phys. 187, 261, 1999), they have been widely regarded as slow magneto-acoustic waves, due to their observed velocities and periods. However, recent observations have questioned this interpretation, as periodic disturbances in Doppler velocity, line width, and profile asymmetry were found to be in phase with the intensity oscillations (De Pontieu and McIntosh, Astrophys. J. 722, 1013, 2010; Tian, McIntosh, and De Pontieu, Astrophys. J. Lett. 727, L37, 2011), suggesting that the disturbances could be quasi-periodic upflows. Here we conduct a detailed analysis of the velocities of these disturbances across several wavelengths using the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). We analysed 41 examples, including both sunspot and non-sunspot regions of the Sun. We found that the velocities of propagating disturbances (PDs) located at sunspots are more likely to be temperature dependent, whereas the velocities of PDs at non-sunspot locations do not show a clear temperature dependence. This suggests an interpretation in terms of slow magneto-acoustic waves in sunspots but the nature of PDs in non-sunspot (plage) regions remains unclear. We also considered on what scale the underlying driver is affecting the properties of the PDs. Finally, we found that removing the contribution due to the cooler ions in the 193 Å wavelength suggests that a substantial part of the 193 Å emission of sunspot PDs can be attributed to the cool component of 193 Å.

[Pre-travel advice and patient education of Hungarian travellers].

Science.gov (United States)

Lengyel, Ingrid; Felkai, Péter

2018-03-01

According to international surveys, over half of the travellers face some kind of health issue when travelling. The overwhelming majority of travel-related illnesses can be prevented with pre-travel medical consultations, but the syllabus and content of the consultation have to match the travel habits and culture of the given society. This publication explores the specificities and travel habits of Hungarian travellers. One hundred participants of a travel exhibition completed a survey about their international travel. As the survey was not representative, the data could only be processed through simple statistical methods. However, since the exhibition was presumably attended by those wishing to travel, the conclusions drawn from the results are worth publishing, since no similar survey in Hungary has been published before. Based on the suitable classification of age groups in travel medicine, 11% of the participants were adolescents / young adults (aged 15-24), 81% adults (25-59) and 8% elderly (60-74). Twenty-eight percent of the participants travel multiple times a year, 40% yearly and 32% of them less frequently; 16% of the adults, 8% of the adolescents and 4% of the elderly age group travel multiple times a year. The travel destinations of Hungarian travellers have remained practically unchanged since a study was conducted 13 years ago: the vast majority (95%) travelled within Europe, 2% to the United States, and 11% of them elsewhere. Since Hungarians do not travel to endemic areas, only 5% consulted their general practitioners (GPs) prior to travelling, and 29% did when they had to be vaccinated. Forty-two percent of those wishing to travel never consult their GPs, even though 29% of them are aware of some chronic illness. Instead, 51% gather their health information from the internet and only 6% from their doctors. By the contradiction between the poor health status of the majority of Hungarian travellers and the negligence of seeking pre-travel advice

Simultaneous ground-satellite observations of daytime traveling ionospheric disturbances over Japan using the GPS-TEC network and the CHAMP satellite

Science.gov (United States)

Moral, A. C.; Shiokawa, K.; Otsuka, Y.; Liu, H.; Nishioka, M.; Tsugawa, T.

2017-12-01

We report results of simultaneous ground-satellite measurements of daytime travelling ionospheric disturbances (TIDs) over Japan by using the GEONET GPS receiver network and the CHAMP satellite. For the two years of 2002 and 2008, we examined GPS measurements of TEC (Total Electron Content) and neutral and electron densities measured by CHAMP satellite. Total of fifteen TID events with clear southward moving structures in the GPS-TEC measurements are found by simultaneous ground-satellite measurements. On 2002, simultaneous events are only observed in January (1 event) and February (4 events). On 2008, ten events are observed around winter months (January (3 events), February (5), March (1), and October (1)). Neutral and electron densities measured by CHAMP show quasi-periodic fluctuations throughout the passages for all events. The CHAMP satellite crossed at least one clear TID phase front for all the events. We fitted a sinusoidal function to both ground and satellite data to obtain the frequencies and phase of the observed variations. We calculated the corresponding phase relationships between TEC variations and neutral and electron densities measured by CHAMP to categorize the events. In the presentations we report correspondence of these TID structures seen in the simultaneous ground-satellite observations by GPS-TEC and CHAMP, and discuss their phase relationship to identify the source of the daytime TIDs and specify how much of the observed variations are showing clear frequencies/or not in the nature at middle latitudes.

Ocean-atmosphere interaction and synoptic weather conditions in ...

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

turbances over oceans. On the other hand, these disturbances have an impact on the oceanic mixed layer, causing changes in the SST. This complex feed back process between the sea surface and the atmospheric disturbances is important in deter- mining the life span of the synoptic scale events. (Paul et al 1992). In view ...

Neurology of microgravity and space travel

Science.gov (United States)

Fujii, M. D.; Patten, B. M.

1992-01-01

Exposure to microgravity and space travel produce several neurologic changes, including SAS, ataxia, postural disturbances, perceptual illusions, neuromuscular weakness, and fatigue. Inflight SAS, perceptual illusions, and ocular changes are of more importance. After landing, however, ataxia, perceptual illusions, neuromuscular weakness, and fatigue play greater roles in astronaut health and readaptation to a terrestrial environment. Cardiovascular adjustments to microgravity, bone demineralization, and possible decompression sickness and excessive radiation exposure contribute further to medical problems of astronauts in space. A better understanding of the mechanisms by which microgravity adversely affects the nervous system and more effective treatments will provide healthier, happier, and longer stays in space on the space station Freedom and during the mission to Mars.

NADIM-Travel: A Multiagent Platform for Travel Services Aggregation

OpenAIRE

Ben Ameur, Houssein; Bédard, François; Vaucher, Stéphane; Kropf, Peter; Chaib-draaa, Brahim; Gérin-Lajoie, Robert

2010-01-01

With the Internet as a growing channel for travel services distribution, sophisticated travel services aggregators are increasingly in demand. A travel services aggregation platform should be able to manage the heterogeneous characteristics of the many existing travel services. It should also be as scalable, robust, and flexible as possible. Using multiagent technology, we designed and implemented a multiagent platform for travel services aggregation called NADIM-Travel. In this platform, a p...

Age structure and disturbance legacy of North American forests

Directory of Open Access Journals (Sweden)

Y. Pan

2011-03-01

Full Text Available Most forests of the world are recovering from a past disturbance. It is well known that forest disturbances profoundly affect carbon stocks and fluxes in forest ecosystems, yet it has been a great challenge to assess disturbance impacts in estimates of forest carbon budgets. Net sequestration or loss of CO₂ by forests after disturbance follows a predictable pattern with forest recovery. Forest age, which is related to time since disturbance, is a useful surrogate variable for analyses of the impact of disturbance on forest carbon. In this study, we compiled the first continental forest age map of North America by combining forest inventory data, historical fire data, optical satellite data and the dataset from NASA's Landsat Ecosystem Disturbance Adaptive Processing System (LEDAPS project. A companion map of the standard deviations for age estimates was developed for quantifying uncertainty. We discuss the significance of the disturbance legacy from the past, as represented by current forest age structure in different regions of the US and Canada, by analyzing the causes of disturbances from land management and nature over centuries and at various scales. We also show how such information can be used with inventory data for analyzing carbon management opportunities. By combining geographic information about forest age with estimated C dynamics by forest type, it is possible to conduct a simple but powerful analysis of the net CO₂ uptake by forests, and the potential for increasing (or decreasing this rate as a result of direct human intervention in the disturbance/age status. Finally, we describe how the forest age data can be used in large-scale carbon modeling, both for land-based biogeochemistry models and atmosphere-based inversion models, in order to improve the spatial accuracy of carbon cycle simulations.

Travel health attitudes among Turkish business travellers to African countries.

Science.gov (United States)

Selcuk, Engin Burak; Kayabas, Uner; Binbasioglu, Hulisi; Otlu, Baris; Bayindir, Yasar; Bozdogan, Bulent; Karatas, Mehmet

The number of international travellers is increasing worldwide. Although health risks related to international travel are important and generally well-understood, the perception of these risks was unclear among Turkish travellers. We aimed to evaluate the attitudes and health risk awareness of Turkish travellers travelling to African countries. A survey was performed of Turkish travellers bound for Africa from Istanbul International Ataturk Airport in July 2013. A total of 124 travellers were enrolled in the study. Among them, 62.9% had information about their destination but only 11.3% had looked for information on health problems related to travel and their destination. Of all travellers, 53.2% had at least one vaccination before travelling. The most commonly administered vaccine was for typhoid. Among the travellers, 69.3% and 80.6% had "no idea" about yellow fever vaccination and malaria prophylaxis, respectively. A positive correlation was found between a higher level of travellers' education and receiving the recommended vaccination for the destination. Our study revealed significant gaps in the vaccination and chemoprophylaxis uptake of Turkish travellers departing to Africa. An awareness and training program should be developed for travellers, as well as public health workers, to address health risks related to travel. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characteristics and pre-travel preparation of travelers at a Canadian pediatric tertiary care travel clinic: A retrospective analysis.

Science.gov (United States)

Ma, Xiao Wei; Pell, Lisa G; Akseer, Nadia; Khan, Sarah; Lam, Ray E; Louch, Debra; Science, Michelle; Morris, Shaun K

2016-01-01

International travelers are susceptible to a wide spectrum of travel related morbidities. Despite rising number of international travelers in Canada, the demographics, risk profiles, and preventative strategies of high-risk traveler groups, including pediatric travelers visiting friends and relatives (VFRs) are not well described. A descriptive analysis was conducted on pre-travel consultations completed between January 2013 and August 2014 at a large pediatric tertiary care center in Toronto, Canada. Data on demographics, travel characteristics, and pre-travel interventions were extracted from 370 pre-travel consultations. Results were compared between all VFR and non-VFR travelers, as well as between children traveling to visit friends and relatives, for vacation, and for education and/or volunteer purposes. Forty-eight percent of consultations were for children travel to visit friends and/or relatives than for other purposes (29% vs 9%, p travel for >28 days than children traveling for vacation (43% vs 1%, p traveling for education/volunteer purposes (43% vs 21%, p = 0.03). Around half of cVFRs traveled to destinations in Asia (51%). The majority stayed with locals, friends and/or relatives (85%), and nearly all traveled to urban destinations (98%). The most prescribed interventions for children were azithromycin (84%), Dukoral (66%), and the hepatitis A vaccine (60%). Atovaquone/proguanil was the most commonly prescribed antimalarial for children. Children that travel to visit friends and relatives represent a unique travel group and may require specific considerations during pre-travel preparations. Our findings can help develop targeted pre-travel strategies for children VFRs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Travellers' profile, travel patterns and vaccine practices--a 10-year prospective study in a Swiss Travel Clinic.

Science.gov (United States)

Boubaker, Rim; Meige, Pierrette; Mialet, Catherine; Buffat, Chantal Ngarambe; Uwanyiligira, Mediatrice; Widmer, Francine; Rochat, Jacynthe; Fossati, Annie Hérard; Souvannaraj-Blanchant, Manisinh; Payot, Sylvie; Rochat, Laurence; de Vallière, Serge; Genton, Blaise; D'Acremont, Valérie

2016-01-01

The travel clinic in Lausanne serves a catchment area of 700 000 of inhabitants and provides pre- and post-travel consultations. This study describes the profile of attendees before departure, their travel patterns and the travel clinic practices in terms of vaccination over time. We included all pre-travel first consultation data recorded between November 2002 and December 2012 by a custom-made program DIAMM/G. We analysed client profiles, travel characteristics and vaccinations prescribed over time. Sixty-five thousand and forty-six client-trips were recorded. Fifty-one percent clients were female. Mean age was 32 years. In total, 0.1% were aged travellers had pre-existing medical conditions. Forty-six percent were travelling to Africa, 35% to Asia, 20% to Latin America and 1% (each) to Oceania and Europe; 19% visited more than one country. India was the most common destination (9.6% of travellers) followed by Thailand (8.6%) and Kenya (6.4%). Seventy-three percent of travellers were planning to travel for ≤ 4 weeks. The main reasons for travel were tourism (75%) and visiting friends and relatives (18%). Sixteen percent were backpackers. Pre-travel advice were sought a median of 29 days before departure. Ninety-nine percent received vaccine(s). The most frequently administered vaccines were hepatitis A (53%), tetanus-diphtheria (46%), yellow fever (39%), poliomyelitis (38%) and typhoid fever (30%). The profile of travel clinic attendees was younger than the general Swiss population. A significant proportion of travellers received vaccinations that are recommended in the routine national programme. These findings highlight the important role of travel clinics to (i) take care of an age group that has little contact with general practitioners and (ii) update vaccination status. The most commonly prescribed travel-related vaccines were for hepatitis A and yellow fever. The question remains to know whether clients do attend travel clinics because of compulsory

Danish long distance travel A study of Danish travel behaviour and the role of infrequent travel activities

DEFF Research Database (Denmark)

Knudsen, Mette Aagaard

2014-01-01

, this is problematic. The average travel distance has steadily increased during the latest decades together with the increasing motorisation of daily travel and international aviation. Previously most focus has been on domestic daily travel activities, but globalisation has, together with changes in price structures......), the TU overnight survey, and the Danish Tourism Statistics from the Business and Holiday Survey (HBS). This has enabled focus on infrequent travel activities segmented relative to travel purpose, distance threshold, or travelling with overnight stays. At an overall level the thesis has three main.......g. socio-economic variables. The analysis of Danish travel activities described in the three different travel surveys has outlined detailed information on Danish travel behaviour at an aggregated level during the past two decades. It has above all revealed the significant role of leisure travel. Private...

Common Observations for Near-Source Ground Motions and Seismo-Traveling Ionosphere Disturbances Following the 2011 off the Pacific Coast of Tohoku Earthquake, Japan

Directory of Open Access Journals (Sweden)

Bor-Shouh Huang

2012-01-01

Full Text Available The time history and spatial dependence of seismic-wave propagation on the ground surface and through the ionosphere following the 2011 off the Pacific coast of Tohoku Earthquake were reconstructed from dense seismic networks and from Global Positioning System (GPS array observations, respectively. Using total electron content (TEC data recorded by a dense GPS receiver network, the near-source ionosphere perturbations induced by this giant earthquake were analyzed and high-resolution images of seismic-wave propagation in the ionosphere are presented. Similar spatial images of ground motions were reconstructed from observations by a dense seismic array. Observations of this event provide, for the first time, the opportunity to compare near-source ground motions with the near-field seismo-traveling ionosphere disturbance (STID excited by the ground motions. Based on the results, the nature of the source rupture and seismic-wave propagation are discussed. Both seismic and ionosphere observations indicate that seismic energy propagated radially outward initially from the hypocenter, but that the circular shape of the propagation front became gradually distorted as the source rupture became extended. Coherent wavefronts from the two analyses show contrasting patterns during the later stage of propagation, possibly due to different patterns of spatial variations in the physical properties of the solid earth and of the ionosphere.

Proposed preliminary definition of the disturbed-zone boundary appropriate for a repository at Yucca Mountain

International Nuclear Information System (INIS)

Langkopf, B.S.

1987-12-01

Some of the calculations that support the licensing of a repository for high-level radioactive waste will use the regulatory concept of a disturbed zone. The Nevada Nuclear Waste Storage Investigations (NNWSI) project must determine the location of the boundary of the disturbed zone for use in these calculations. This paper summarizes results of computer analyses and laboratory experiments and suggests a preliminary definition for the boundary of the disturbed zone for the unsaturated environment at Yucca Mountain. Although the intent of this paper is to define the boundary of the disturbed zone at the edge of significant changes in intrinsic hydrologic properties, there is no evidence of changes in intrinsic hydrologic properties that could significantly change the groundwater travel time from the repository to the water table. Such a result suggests that the disturbed zone at Yucca Mountain is of minimal extent. Because the analyses and experiments reviewed here indicate that there are a variety of changes near the waste package and because the results are subject to uncertainty, the preliminary suggestion for the extent of the disturbed zone is a value larger than the results themselves would suggest: the boundary is proposed to be a plane 10 m below the lower boundary of the waste packages. 88 refs., 12 figs., 5 tabs

Demographics, health and travel characteristics of international travellers at a pre-travel clinic in Marseille, France.

Science.gov (United States)

Aubry, Camille; Gaudart, Jean; Gaillard, Catherine; Delmont, Jean; Parola, Philippe; Brouqui, Philippe; Gautret, Philippe

2012-09-01

With the aim to identify at-risk individuals among a cohort of international travellers, 3442 individuals who sought advice at Marseille travel health centre in 2009 were prospectively included. Demographics, travel characteristics, chronic medical conditions, vaccinations and antimalarial chemoprophylaxis were documented. Chronic medical conditions were reported by 11% of individuals, including hypertension (39%), asthma (20%), thyroid disease (15%) and depression (13%). 4% reported taking a daily medication, and psychotropic and cardiovascular medications were the most commonly used. Older travellers (≥60 years) accounted for 10% of the travellers and the prevalence of chronic medical conditions was 27% in this group. Individuals aged 15 years or less accounted for 13% of the travellers. Age, last minute travel (17%) and neurological and psychiatric diseases were the most frequent factors that influenced Yellow fever vaccination and malaria chemoprophylaxis, with more than one tenth of the travellers reporting at least one risk factor for which adjusted advice may be necessary. Migrants visiting their relatives in their origin country accounted for 14% of travellers and 73% of this group travelled with their family including young children. We demonstrate that a significant proportion of travellers are at-risk (43%) because of their travel conditions (VFR), their age, or their health status, and should be targeted for risk reduction strategies. Copyright © 2012 Elsevier Ltd. All rights reserved.

Nonlinear Development and Secondary Instability of Traveling Crossflow Vortices

Science.gov (United States)

Li, Fei; Choudhari, Meelan M.; Duan, Lian; Chang, Chau-Lyan

2014-01-01

Transition research under NASA's Aeronautical Sciences Project seeks to develop a validated set of variable fidelity prediction tools with known strengths and limitations, so as to enable "sufficiently" accurate transition prediction and practical transition control for future vehicle concepts. This paper builds upon prior effort targeting the laminar breakdown mechanisms associated with stationary crossflow instability over a swept-wing configuration relevant to subsonic aircraft with laminar flow technology. Specifically, transition via secondary instability of traveling crossflow modes is investigated as an alternate scenario for transition. Results show that, for the parameter range investigated herein, secondary instability of traveling crossflow modes becomes insignificant in relation to the secondary instability of the stationary modes when the relative initial amplitudes of the traveling crossflow instability are lower than those of the stationary modes by approximately two orders of magnitudes or more. Linear growth predictions based on the secondary instability theory are found to agree well with those based on PSE and DNS, with the most significant discrepancies being limited to spatial regions of relatively weak secondary growth, i.e., regions where the primary disturbance amplitudes are smaller in comparison to its peak amplitude. Nonlinear effects on secondary instability evolution is also investigated and found to be initially stabilizing, prior to breakdown.

Individual traveller health priorities and the pre-travel health consultation.

Science.gov (United States)

Flaherty, Gerard T; Chen, Bingling; Avalos, Gloria

2017-09-01

The purpose of this study was to examine the principal travel health priorities of travellers. The most frequently selected travel health concerns were accessing medical care abroad, dying abroad, insect bites, malaria, personal safety and travel security threats. The travel health risks of least concern were culture shock, fear of flying, jet lag and sexually transmitted infections. This study is the first to develop a hierarchy of self-declared travel health risk priorities among travellers. © International Society of Travel Medicine, 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Extratropical Weather Systems on Mars: Radiatively-Active Water Ice Effects

Science.gov (United States)

Hollingsworth, J. L.; Kahre, M. A.; Haberle, R. M.; Urata, R. A.; Montmessin, F.

2017-01-01

Extratropical, large-scale weather disturbances, namely transient, synoptic-period,baroclinic barotropic eddies - or - low- (high-) pressure cyclones (anticyclones), are components fundamental to global circulation patterns for rapidly rotating, differentially heated, shallow atmospheres such as Earth and Mars. Such "wave-like" disturbances that arise via (geophysical) fluid shear instability develop, mature and decay, and travel west-to-east in the middle and high latitudes within terrestrial-like planetary atmospheres. These disturbances serve as critical agents in the transport of heat and momentum between low and high latitudes of the planet. Moreover, they transport trace species within the atmosphere (e.g., water vapor/ice, other aerosols (dust), chemical species, etc). Between early autumn through early spring, middle and high latitudes on Mars exhibit strong equator-to-pole mean temperature contrasts (i.e., "baroclinicity"). Data collected during the Viking era and observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that such strong baroclinicity supports vigorous, large-scale eastward traveling weather systems [Banfield et al., 2004; Barnes et al., 1993]. A good example of traveling weather systems, frontal wave activity and sequestered dust activity from MGS/MOC image analyses is provided in Figure 1 (cf. Wang et al. [2005]). Utilizing an upgraded and evolving version of the NASA Ames Research Center (ARC) Mars global climate model, investigated here are key dynamical and physical aspects of simulated northern hemisphere (NH) large-scale extratropica lweather systems,with and without radiatively-active water ice clouds. Mars Climate Model:

On the propagation of a quasi-static disturbance in a heterogeneous, deformable, and porous medium with pressure-dependent properties

Energy Technology Data Exchange (ETDEWEB)

Vasco, D.W.

2011-10-01

Using an asymptotic technique, valid when the medium properties are smoothly-varying, I derive a semi-analytic expression for the propagation velocity of a quasi-static disturbance traveling within a nonlinear-elastic porous medium. The phase, a function related to the propagation time, depends upon the properties of the medium, including the pressure-sensitivities of the medium parameters, and on pressure and displacement amplitude changes. Thus, the propagation velocity of a disturbance depends upon its amplitude, as might be expected for a nonlinear process. As a check, the expression for the phase function is evaluated for a poroelastic medium, when the material properties do not depend upon the fluid pressure. In that case, the travel time estimates agree with conventional analytic estimates, and with values calculated using a numerical simulator. For a medium with pressure-dependent permeability I find general agreement between the semi-analytic estimates and estimates from a numerical simulation. In this case the pressure amplitude changes are obtained from the numerical simulator.

Connected Traveler

Energy Technology Data Exchange (ETDEWEB)

2016-06-01

The Connected Traveler framework seeks to boost the energy efficiency of personal travel and the overall transportation system by maximizing the accuracy of predicted traveler behavior in response to real-time feedback and incentives. It is anticipated that this approach will establish a feedback loop that 'learns' traveler preferences and customizes incentives to meet or exceed energy efficiency targets by empowering individual travelers with information needed to make energy-efficient choices and reducing the complexity required to validate transportation system energy savings. This handout provides an overview of NREL's Connected Traveler project, including graphics, milestones, and contact information.

Discovery of Ubiquitous Fast-Propagating Intensity Disturbances by the Chromospheric Lyman Alpha Spectropolarimeter (CLASP)

Science.gov (United States)

Kubo, M.; Katsukawa, Y.; Suematsu, Y.; Kano, R.; Bando, T.; Narukage, N.; Ishikawa, R.; Hara, H.; Giono, G.; Tsuneta, S.; Ishikawa, S.; Shimizu, T.; Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.; Auchère, F.; Trujillo Bueno, J.; Asensio Ramos, A.; Štěpán, J.; Belluzzi, L.; Manso Sainz, R.; De Pontieu, B.; Ichimoto, K.; Carlsson, M.; Casini, R.; Goto, M.

2016-12-01

High-cadence observations by the slit-jaw (SJ) optics system of the sounding rocket experiment known as the Chromospheric Lyman Alpha Spectropolarimeter (CLASP) reveal ubiquitous intensity disturbances that recurrently propagate in either the chromosphere or the transition region or both at a speed much higher than the speed of sound. The CLASP/SJ instrument provides a time series of two-dimensional images taken with broadband filters centered on the Lyα line at a 0.6 s cadence. The multiple fast-propagating intensity disturbances appear in the quiet Sun and in an active region, and they are clearly detected in at least 20 areas in a field of view of 527″ × 527″ during the 5 minute observing time. The apparent speeds of the intensity disturbances range from 150 to 350 km s-1, and they are comparable to the local Alfvén speed in the transition region. The intensity disturbances tend to propagate along bright elongated structures away from areas with strong photospheric magnetic fields. This suggests that the observed fast-propagating intensity disturbances are related to the magnetic canopy structures. The maximum distance traveled by the intensity disturbances is about 10″, and the widths are a few arcseconds, which are almost determined by a pixel size of 1.″03. The timescale of each intensity pulse is shorter than 30 s. One possible explanation for the fast-propagating intensity disturbances observed by CLASP is magnetohydrodynamic fast-mode waves.

DISCOVERY OF UBIQUITOUS FAST-PROPAGATING INTENSITY DISTURBANCES BY THE CHROMOSPHERIC LYMAN ALPHA SPECTROPOLARIMETER (CLASP)

International Nuclear Information System (INIS)

Kubo, M.; Katsukawa, Y.; Suematsu, Y.; Kano, R.; Bando, T.; Narukage, N.; Ishikawa, R.; Hara, H.; Giono, G.; Tsuneta, S.; Ishikawa, S.; Shimizu, T.; Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.; Auchère, F.; Bueno, J. Trujillo; Ramos, A. Asensio

2016-01-01

High-cadence observations by the slit-jaw (SJ) optics system of the sounding rocket experiment known as the Chromospheric Lyman Alpha Spectropolarimeter (CLASP) reveal ubiquitous intensity disturbances that recurrently propagate in either the chromosphere or the transition region or both at a speed much higher than the speed of sound. The CLASP/SJ instrument provides a time series of two-dimensional images taken with broadband filters centered on the Ly α line at a 0.6 s cadence. The multiple fast-propagating intensity disturbances appear in the quiet Sun and in an active region, and they are clearly detected in at least 20 areas in a field of view of 527″ × 527″ during the 5 minute observing time. The apparent speeds of the intensity disturbances range from 150 to 350 km s −1 , and they are comparable to the local Alfvén speed in the transition region. The intensity disturbances tend to propagate along bright elongated structures away from areas with strong photospheric magnetic fields. This suggests that the observed fast-propagating intensity disturbances are related to the magnetic canopy structures. The maximum distance traveled by the intensity disturbances is about 10″, and the widths are a few arcseconds, which are almost determined by a pixel size of 1.″03. The timescale of each intensity pulse is shorter than 30 s. One possible explanation for the fast-propagating intensity disturbances observed by CLASP is magnetohydrodynamic fast-mode waves.

Ionospheric disturbances induced by a missile launched from North Korea on 12 December 2012

Science.gov (United States)

Kakinami, Yoshihiro; Yamamoto, Masayuki; Chen, Chia-Hung; Watanabe, Shigeto; Lin, Charles; Liu, Jenn-Yanq; Habu, Hiroto

2013-08-01

disturbances caused by a missile launched from North Korea on 12 December 2012 were investigated by using the GPS total electron content (TEC). The spatial characteristic of the front edge of V-shaped disturbances produced by missiles and rockets was first determined. Considering the launch direction and the height of estimated ionospheric points at which GPS radio signal pierces the ionosphere, the missile passed through the ionosphere at heights of 391, 425, and 435 km at 0056:30, 0057:00, and 0057:30 UT, respectively. The observed velocities of the missile were 2.8 and 3.2 km/s at that time, which was estimated from the traveling speed of the front edge of V-shaped disturbances. Westward and eastward V-shaped disturbances propagated at 1.8-2.6 km/s. The phase velocities of the westward and eastward V-shaped disturbances were much faster than the speed of acoustic waves reported in previous studies, suggesting that sources other than acoustic waves may have played an important role. Furthermore, the plasma density depletion that is often observed following missile and rocket launches was not found. This suggests that the depletion resulting from the missile's exhaust was not strong enough to be observed in the TEC distribution in the topside ionosphere.

Medium-scale traveling ionospheric disturbances over Taiwan observed with HF Doppler sounding

Czech Academy of Sciences Publication Activity Database

Fišer, Jiří; Chum, Jaroslav; Liu, J. Y.

2017-01-01

Roč. 69, č. 1 (2017), č. článku 131. ISSN 1880-5981 R&D Projects: GA ČR(CZ) GC15-07281J Institutional support: RVO:68378289 Keywords : Ionosphere * MSTIDs * HF Doppler sounding * atmospheric gravity-waves * f-region * radar * midlatitudes * GPS * thermosphere * typhoon * propagation * origin * model Subject RIV: DG - Athmosphere Sciences, Meteorology OBOR OECD: Meteorology and atmospheric sciences Impact factor: 2.243, year: 2016 https://link.springer.com/epdf/10.1186/s40623-017-0719-y?author_access_token=2ZsbOK__dXYBPg3JeUnMRG_BpE1tBhCbnbw3BuzI2RPoX9yp_OQ2oidt3ZsPeTu1PzUzaEkwP-1WNoKL6B1OXd0-5E40nSdNe-QGMtoHWSkJ1GBaHrp-FbkCnI1e0lljqxm3v0C2G-fVOGqiWs7_OQ%3D%3D

Risk factors and pre-travel healthcare of international travellers attending a Dutch travel clinic: a cross-sectional analysis.

Science.gov (United States)

Wieten, Rosanne W; van der Schalie, Maurice; Visser, Benjamin J; Grobusch, Martin P; van Vugt, Michèle

2014-01-01

The number of international travellers is currently estimated to exceed one billion annually. To address travel related health risks and facilitate risk reduction strategies, detailed knowledge of travellers' characteristics is important. In this cross-sectional study, data of a 20% sample of travellers visiting the Academic Medical Center (AMC) travel clinic Amsterdam from July 2011 to July 2012 was collected. Itineraries and protection versus exposure rates of preventable infectious diseases were mapped and reported according to STROBE guidelines. 1749 travellers were included. South-Eastern Asia, South-America and West-Africa were most frequently visited. 26.2% of the population had pre-existing medical conditions (often cardiovascular). Young and VFR travellers had a longer median travel time (28 and 30 days) compared to the overall population (21 days). Young adult travellers were relatively often vaccinated against hepatitis B (43.9% vs. 20.5%, p travellers. Pre-travel guidelines were well adhered to. Young adult travellers had high-risk itineraries but were adequately protected. Improvement of hepatitis B and rabies protection would be desirable, specifically for VFRs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Virtual Travel Agencies - Tourist Value through Travel Information Systems

OpenAIRE

Anckar, Bill

1999-01-01

Anckar, B. (1999), ?Virtual Travel Agencies - Tourist Value through Travel Information Systems?. IAMSR Research Report 5/99. Institute for Advanced Management Systems Research, ?bo Akademi University. As electronic commerce enables the tourist service providers to sell their products directly to the consumer, travel agencies are faced with the imminent threat of being by-passed in the travel industry chain in the information age. This paper suggests that virtual travel agencies can compete su...

Travel expenses

OpenAIRE

Pištěková, Petra

2014-01-01

The thesis "Travel expenses" is dedicated to the travel expenses according to Czech legislation. The aim is to describe the travel reimbursement and to analyze the providing of compensation travel expenses on example of the elementary art school Zruč nad Sázavou. The purpose of this analysis is primarily to find an optimal solution to the problem of determining the place of regular workplace for the travel expenses. The theoretical part focuses on the identification and definition of all prin...

Travelers' Health: Rubella

Science.gov (United States)

... Stamaril clinics Disease Directory Resources Resources for Travelers Adventure Travel Animal Safety Blood Clots Bug Bites Evite ... Minute Travel Long-Term Travel Mass Gatherings Medical Tourism Mental Health Motion Sickness Natural Disasters Pregnant Travelers ...

Impacts of large-scale climatic disturbances on the terrestrial carbon cycle

Directory of Open Access Journals (Sweden)

Lucht Wolfgang

2006-07-01

Full Text Available Abstract Background The amount of carbon dioxide in the atmosphere steadily increases as a consequence of anthropogenic emissions but with large interannual variability caused by the terrestrial biosphere. These variations in the CO2 growth rate are caused by large-scale climate anomalies but the relative contributions of vegetation growth and soil decomposition is uncertain. We use a biogeochemical model of the terrestrial biosphere to differentiate the effects of temperature and precipitation on net primary production (NPP and heterotrophic respiration (Rh during the two largest anomalies in atmospheric CO2 increase during the last 25 years. One of these, the smallest atmospheric year-to-year increase (largest land carbon uptake in that period, was caused by global cooling in 1992/93 after the Pinatubo volcanic eruption. The other, the largest atmospheric increase on record (largest land carbon release, was caused by the strong El Niño event of 1997/98. Results We find that the LPJ model correctly simulates the magnitude of terrestrial modulation of atmospheric carbon anomalies for these two extreme disturbances. The response of soil respiration to changes in temperature and precipitation explains most of the modelled anomalous CO2 flux. Conclusion Observed and modelled NEE anomalies are in good agreement, therefore we suggest that the temporal variability of heterotrophic respiration produced by our model is reasonably realistic. We therefore conclude that during the last 25 years the two largest disturbances of the global carbon cycle were strongly controlled by soil processes rather then the response of vegetation to these large-scale climatic events.

The thermospheric effects of a rapid polar cap expansion

Directory of Open Access Journals (Sweden)

D. W. Idenden

Full Text Available In a previous publication we used results from a coupled thermosphere-ionosphere-plasmasphere model to illustrate a new mechanism for the formation of a large-scale patch of ionisation arising from a rapid polar cap expansion. Here we describe the thermospheric response to that polar cap expansion, and to the ionospheric structure produced. The response is dominated by the energy and momentum input at the dayside throat during the expansion phase itself. These inputs give rise to a large-scale travelling atmospheric disturbance (TAD that propagates both antisunward across the polar cap and equatorward at speeds much greater than both the ion drifts and the neutral winds. We concentrate only on the initially poleward travelling disturbance. The disturbance is manifested in the neutral temperature and wind fields, the height of the pressure level surfaces and in the neutral density at fixed heights. The thermospheric effects caused by the ionospheric structure produced during the expansion are hard to discern due to the dominating effects of the TAD.

Key words. Ionosphere (ionosphere · atmosphere interaction; modeling and forecasting; plasma convection.

77 FR 5252 - Federal Travel Regulation; GSA E-Gov Travel Service (ETS) Transition to E-Gov Travel Service 2...

Science.gov (United States)

2012-02-02

... Travel Regulation; GSA E-Gov Travel Service (ETS) Transition to E-Gov Travel Service 2 (ETS2) AGENCY..., ETS Program Manager Center for Travel Management (QMCD), Office of Travel and Transportation Services (QMC), at [email protected] or (703) 605-2151. SUPPLEMENTARY INFORMATION: The Federal Travel...

Vaccination knowledge, attitude and practice among Chinese travelers who visit travel clinics in Preparation for international travel.

Science.gov (United States)

Zhang, Min; Zhang, Jianming; Hao, Yutong; Fan, ZhengXing; Li, Lei; Li, Yiguang; Ju, Wendong; Zhang, Hong; Liu, Wei; Zhang, Mengzhang; Wu, Di; He, Hongtao

2016-06-01

Although international travel has become increasingly more common in main land China, few data are available on vaccination knowledge, attitude and practice (KAP) among Chinese travelers. In each of 14 International Travel Healthcare Centers (ITHCs) situated in mainland China 200 volunteers were recruited for a cross-sectional investigation by questionnaire on KAP related to travel vaccinations. For the evaluation the study subjects were grouped by demographic data, past travel experience, travel destination, duration of stay abroad, purpose of travel. Among the 2,800 Chinese travelers who participated in the study, 67.1% were aware of national and travel vaccination recommendations. The knowledge about vaccine preventable diseases was low. The most common sources (73.4%) of information were requirements by destination countries obtained in connection with the visa application, Chinese companies employing workers/laborers for assignments overseas, and foreign schools. The overall acceptance rate of recommended vaccines was 68.7%, but yellow fever was accepted by 99.8% of the participants when recommended. Among 81.1% respondents who recalled to have received vaccinations in the past, only 25.9% of them brought the old vaccination records with them to their ITHC consultations. The results indicate that increased awareness of the importance of pre-travel vaccination is needed among the travellers in order to improve their KAP. © International Society of Travel Medicine, 2016. All rights reserved. Published by Oxford University Press. For permissions, please e-mail: journals.permissions@oup.com.

Valuation of Travel Time and TravelIer Information

NARCIS (Netherlands)

Rietveld, Piet

2003-01-01

The value of travel time plays an important role in cost benefit analysis of infrastructureprojects. However, the issue of uncertainty on travel times and the implications this has forestimations of travel time values has received much less attention in the literature. In thispaper we compare

DISCOVERY OF UBIQUITOUS FAST-PROPAGATING INTENSITY DISTURBANCES BY THE CHROMOSPHERIC LYMAN ALPHA SPECTROPOLARIMETER (CLASP)

Energy Technology Data Exchange (ETDEWEB)

Kubo, M.; Katsukawa, Y.; Suematsu, Y.; Kano, R.; Bando, T.; Narukage, N.; Ishikawa, R.; Hara, H.; Giono, G. [National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Tsuneta, S.; Ishikawa, S.; Shimizu, T.; Sakao, T. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Winebarger, A.; Kobayashi, K.; Cirtain, J. [NASA Marshall Space Flight Center, ZP 13, Huntsville, AL 35812 (United States); Champey, P. [University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, AL 35899 (United States); Auchère, F. [Institut d’Astrophysique Spatiale, CNRS/Univ. Paris-Sud 11, Bâtiment 121, F-91405 Orsay (France); Bueno, J. Trujillo; Ramos, A. Asensio, E-mail: masahito.kubo@nao.ac.jp [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain); and others

2016-12-01

High-cadence observations by the slit-jaw (SJ) optics system of the sounding rocket experiment known as the Chromospheric Lyman Alpha Spectropolarimeter (CLASP) reveal ubiquitous intensity disturbances that recurrently propagate in either the chromosphere or the transition region or both at a speed much higher than the speed of sound. The CLASP/SJ instrument provides a time series of two-dimensional images taken with broadband filters centered on the Ly α line at a 0.6 s cadence. The multiple fast-propagating intensity disturbances appear in the quiet Sun and in an active region, and they are clearly detected in at least 20 areas in a field of view of 527″ × 527″ during the 5 minute observing time. The apparent speeds of the intensity disturbances range from 150 to 350 km s{sup −1}, and they are comparable to the local Alfvén speed in the transition region. The intensity disturbances tend to propagate along bright elongated structures away from areas with strong photospheric magnetic fields. This suggests that the observed fast-propagating intensity disturbances are related to the magnetic canopy structures. The maximum distance traveled by the intensity disturbances is about 10″, and the widths are a few arcseconds, which are almost determined by a pixel size of 1.″03. The timescale of each intensity pulse is shorter than 30 s. One possible explanation for the fast-propagating intensity disturbances observed by CLASP is magnetohydrodynamic fast-mode waves.

Disturbance hydrology: Preparing for an increasingly disturbed future

Science.gov (United States)

Mirus, Benjamin B.; Ebel, Brian A.; Mohr, Christian H.; Zegre, Nicolas

2017-01-01

This special issue is the result of several fruitful conference sessions on disturbance hydrology, which started at the 2013 AGU Fall Meeting in San Francisco and have continued every year since. The stimulating presentations and discussions surrounding those sessions have focused on understanding both the disruption of hydrologic functioning following discrete disturbances, as well as the subsequent recovery or change within the affected watershed system. Whereas some hydrologic disturbances are directly linked to anthropogenic activities, such as resource extraction, the contributions to this special issue focus primarily on those with indirect or less pronounced human involvement, such as bark-beetle infestation, wildfire, and other natural hazards. However, human activities are enhancing the severity and frequency of these seemingly natural disturbances, thereby contributing to acute hydrologic problems and hazards. Major research challenges for our increasingly disturbed planet include the lack of continuous pre- and post-disturbance monitoring, hydrologic impacts that vary spatially and temporally based on environmental and hydroclimatic conditions, and the preponderance of overlapping or compounding disturbance sequences. In addition, a conceptual framework for characterizing commonalities and differences among hydrologic disturbances is still in its infancy. In this introduction to the special issue, we advance the fusion of concepts and terminology from ecology and hydrology to begin filling this gap. We briefly explore some preliminary approaches for comparing different disturbances and their hydrologic impacts, which provides a starting point for further dialogue and research progress.

Self-evaluations of factors promoting and disturbing sleep: an epidemiological survey in Finland.

Science.gov (United States)

Urponen, H; Vuori, I; Hasan, J; Partinen, M

1988-01-01

The purpose of this epidemiological survey (N = 1600) was to describe the factors which middle-aged urban people in Finland perceived as promoting or disturbing sleep. The response rate was 75%. The results suggested that quality of sleep is determined by numerous factors; social and psychological factors, health status, external sleeping conditions, life style and living habits. Every third respondent felt that exercise had a positive impact on sleep. Second in importance were reading and listening to music. Furthermore, sauna, shower and bath, stability in life, psychological factors, positive experience in work, satisfactory sexual life and good and quiet sleeping environment were reported to have positive effects on sleep. Men considered work-related pressure and fatigue (20%) as the most important factor disturbing falling asleep or quality of sleep. In women's ranking work problems appeared no sooner than in the third place. Women reported worries, interpersonal problems, and marital and family discord as the most disturbing factors to sleep (37%). Coffee in the evening had a negative effect on falling asleep. Although a 'nightcap' was considered to improve relaxation on falling sleep, men ranked alcohol as the fourth disturbing factor. Other disturbing factors were stress, irregularities in everyday life because of social events, travelling or atypical catnaps. Eating and exercising too heavily or too late in the evening were found to disturb sleep. On the other hand, temporary lack of exercise seemed to impair the quality of sleep. As external factors disturbing sleep the subjects considered noise light, too high room temperature, tight clothing, unfamiliar sleeping environment and restless children.(ABSTRACT TRUNCATED AT 250 WORDS)

International travel patterns and travel risks for stem cell transplant recipients.

Science.gov (United States)

Mikati, Tarek; Griffin, Kenneth; Lane, Dakotah; Matasar, Matthew; Shah, Monika K

2015-01-01

Stem cell transplantation (SCT) is being increasingly utilized for multiple medical illnesses. However, there is limited knowledge about international travel patterns and travel-related illnesses of stem cell transplant recipients (SCTRs). An observational cross-sectional study was conducted among 979 SCTRs at Memorial Sloan Kettering Cancer Center using a previously standardized and validated questionnaire. International travel post SCT, pre-travel health advice, exposure risks, and travel-related illnesses were queried. A total of 516 SCTRs completed the survey (55% response rate); of these, 40% were allogeneic SCTRs. A total of 229 (44.3%) respondents reported international travel outside the United States and Canada post SCT. The international travel incidence was 32% [95% confidence interval CI 28-36] within 2 years after SCT. Using multivariable Cox regression analysis, variables significantly associated with international travel within first 2 years after SCT were history of international travel prior to SCT [hazard ratio (HR) = 5.3, 95% CI 2.3-12.0], autologous SCT (HR = 2.6, 95% CI 1.6-2.8), foreign birth (HR = 2.3, 95% CI 1.5-3.3), and high income (HR = 2.0, 95% CI 1.8-3.7). During their first trip, 64 travelers (28%) had traveled to destinations that may have required vaccination or malaria chemoprophylaxis. Only 56% reported seeking pre-travel health advice. Of those who traveled, 16 travelers (7%) became ill enough to require medical attention during their first trip after SCT. Ill travelers were more likely to have visited high-risk areas (60 vs 26%, p = 0.005), to have had a longer mean trip duration (24 vs 12 days, p = 0.0002), and to have visited friends and relatives (69 vs 21%, p travel was common among SCTRs within 2 years after SCT and was mainly to low-risk destinations. Although the overall incidence of travel-related illnesses was low, certain subgroups of travelers were at a significantly higher risk. Pre-travel

Danish long distance travel A study of Danish travel behaviour and the role of infrequent travel activities

OpenAIRE

Knudsen, Mette Aagaard; Rich, Jeppe; Nielsen, Otto Anker

2014-01-01

Historically there has been a lack of knowledge with respect to long distance travel. Due to the considerable contribution of long distance travel to total travelled kilometres and the related energy consumption from the transport sector and derived impacts on greenhouse emissions, this is problematic. The average travel distance has steadily increased during the latest decades together with the increasing motorisation of daily travel and international aviation. Previously most focus has been...

Travel personae of American pleasure travelers

DEFF Research Database (Denmark)

Park, S.; Tussyadiah, Iis; Mazanec, J.A.

2010-01-01

Travel style has been shown to be a useful concept for understanding travelers. In this study it is argued that the portfolio of trips (specifically, the portfolio of various trip styles) one takes can be used to describe his/her overall travel persona. Network analysis was used to examine...... personae which, in turn, are related to their choices of places visited and their response to advertising materials. It was concluded that the framework provided by these findings along with new tools on the Internet offer the potential to develop highly personalized communications with existing...

Oscillations of stellar extinction caused by disturbances in the Earth's atmosphere

International Nuclear Information System (INIS)

Clarke, D.

1980-01-01

Photometry of bright stars has revealed the possible presence of short period oscillations on the extinction by the Earth's atmosphere. From the colour dependence of the observed effects, it is suggested that the waves affect the aerosol contribution to the extinction more than the contribution by air molecules. The size of the effects presents a challenge to pursuing stellar photometry to accuracies of the order of 0.001 mag. The effects have parallels to the recently discovered brightness oscillations in the daytime sky which have been ascribed to buoyancy or gravity waves in the atmosphere. (author)

Disturbing forest disturbances

Energy Technology Data Exchange (ETDEWEB)

Volney, W.J.A.; Hirsch, K.G. [Natural Resources Canada, Canadian Forest Service, Northern Forestry Centre, Edmonton, AB (Canada)

2005-10-01

This paper described the role that disturbances play in maintaining the ecological integrity of Canadian boreal forests. Potential adaptation options to address the challenges that these disturbances present were also examined. Many forest ecosystems need fire for regeneration, while other forests rely on a cool, wet disintegration process driven by insects and commensal fungi feeding on trees to effect renewal. While there are characteristic natural, temporal and spatial patterns to these disturbances, recent work has demonstrated that the disturbances are being perturbed by climatic change that has been compounded by anthropogenic disturbances in forests. Fire influences species composition and age structure, regulates forest insects and diseases, affects nutrient cycling and energy fluxes, and maintains the productivity of different habitats. Longer fire seasons as a result of climatic change will lead to higher intensity fires that may more easily evade initial attacks and become problematic. Fire regimes elevated beyond the range of natural variation will have a dramatic effect on the regional distribution and functioning of forest ecosystems and pose a threat to the safety and prosperity of people. While it was acknowledged that if insect outbreaks were to be controlled on the entire forest estate, the productivity represented by dead wood would be lost, it was suggested that insects such as the forest tent caterpillar and the spruce bud worm may also pose a greater threat as the climate gets warmer and drier. Together with fungal associates, saproxylic arthropods are active in nutrient cycling and ultimately determine the fertility of forest sites. It was suggested that the production of an age class structure and forest mosaic would render the forest landscape less vulnerable to the more negative aspects of climate change on vegetation response. It was concluded that novel management design paradigms are needed to successfully reduce the risk from threats

Travel itinerary uncertainty and the pre-travel consultation--a pilot study.

Science.gov (United States)

Flaherty, Gerard; Md Nor, Muhammad Najmi

2016-01-01

Risk assessment relies on the accuracy of the information provided by the traveller. A questionnaire was administered to 83 consecutive travellers attending a travel medicine clinic. The majority of travellers was uncertain about destinations within countries, transportation or type of accommodation. Most travellers were uncertain if they would be visiting malaria regions. The degree of uncertainty about itinerary potentially impacts on the ability of the travel medicine specialist to perform an adequate risk assessment, select appropriate vaccinations and prescribe malaria prophylaxis. This study reveals high levels of traveller uncertainty about their itinerary which may potentially reduce the effectiveness of their pre-travel consultation. © The Author 2016. Published by Oxford University Press on behalf of International society of travel medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Observation and simulation of the ionosphere disturbance waves triggered by rocket exhausts

Science.gov (United States)

Lin, Charles C. H.; Chen, Chia-Hung; Matsumura, Mitsuru; Lin, Jia-Ting; Kakinami, Yoshihiro

2017-08-01

Observations and theoretical modeling of the ionospheric disturbance waves generated by rocket launches are investigated. During the rocket passage, time rate change of total electron content (rTEC) enhancement with the V-shape shock wave signature is commonly observed, followed by acoustic wave disturbances and region of negative rTEC centered along the trajectory. Ten to fifteen min after the rocket passage, delayed disturbance waves appeared and propagated along direction normal to the V-shape wavefronts. These observation features appeared most prominently in the 2016 North Korea rocket launch showing a very distinct V-shape rTEC enhancement over enormous areas along the southeast flight trajectory despite that it was also appeared in the 2009 North Korea rocket launch with the eastward flight trajectory. Numerical simulations using the physical-based nonlinear and nonhydrostatic coupled model of neutral atmosphere and ionosphere reproduce promised results in qualitative agreement with the characteristics of ionospheric disturbance waves observed in the 2009 event by considering the released energy of the rocket exhaust as the disturbance source. Simulations reproduce the shock wave signature of electron density enhancement, acoustic wave disturbances, the electron density depletion due to the rocket-induced pressure bulge, and the delayed disturbance waves. The pressure bulge results in outward neutral wind flows carrying neutrals and plasma away from it and leading to electron density depletions. Simulations further show, for the first time, that the delayed disturbance waves are produced by the surface reflection of the earlier arrival acoustic wave disturbances.

Increasing referral of at-risk travelers to travel health clinics: evaluation of a health promotion intervention targeted to travel agents.

Science.gov (United States)

MacDougall, L A; Gyorkos, T W; Leffondré, K; Abrahamowicz, M; Tessier, D; Ward, B J; MacLean, J D

2001-01-01

Increases in travel-related illness require new partnerships to ensure travelers are prepared for health risks abroad. The travel agent is one such partner and efforts to encourage travel agents to refer at-risk travelers to travel health clinics may help in reducing travel-attributable morbidity. A health promotion intervention encouraging travel agents to refer at-risk travelers to travel health clinics was evaluated. Information on the knowledge, attitudes, and behaviors of travel agents before and after the intervention was compared using two self-administered questionnaires. The Wilcoxon signed rank test was used to compare the mean difference in overall scores to evaluate the overall impact of the intervention and also subscores for each of the behavioral construct groupings (attitudes, barriers, intent, and subjective norms). Multiple regression techniques were used to evaluate which travel agent characteristics were independently associated with a stronger effect of the intervention. A small improvement in travel agents overall attitudes and beliefs (p =.03) was found, in particular their intention to refer (p =.01). Sixty-five percent of travel agents self-reported an increase in referral behavior; owners or managers of the agency were significantly more likely to do so than other travel agents (OR = 7.25; 95% CI: 1.64 32.06). Older travel agents, those that worked longer hours and those with some past referral experience, had significantly higher post-intervention scores. Travel agents can be willing partners in referral, and agencies should be encouraged to develop specific referral policies. Future research may be directed toward investigating the role of health education in certification curricula, the effectiveness of different types of health promotion interventions, including Internet-facilitated interventions, and the direct impact that such interventions would have on travelers attending travel health clinics.

Human travel and traveling bedbugs.

Science.gov (United States)

Delaunay, Pascal

2012-12-01

A dramatic increase of reported bedbug (Cimex lectularius and Cimex hemipterus) infestations has been observed worldwide over the past decade. Bedbug infestations have also been detected across a wide range of travel accommodations, regardless of their comfort and hygiene levels. Travelers are increasingly exposed to the risks of bedbug bites, infestation of personal belongings, and subsequent contamination of newly visited accommodations and their homes. We searched Medline publications via the PubMed database. National bedbug recommendations, textbooks, newspapers, and Centers for Disease Control websites were also searched manually. To detect infested sites, avoid or limit bedbug bites, and reduce the risk of contaminating one's belongings and home, bedbug biology and ecology must be understood. A detailed search of their most classic hiding niches is a key to finding adult bedbugs, nymphs, eggs, and feces or traces of blood from crushed bedbugs. Locally, bedbugs move by active displacement to feed (bite) during the night. Bed, mattress, sofa, and/or curtains are the most frequently infested places. If you find bedbugs, change your room or, even better, the hotel. Otherwise, travelers should follow recommendations for avoiding bedbugs and their bites during the night and apply certain simple rules to avoid infesting other sites or their home. Travelers exposed to bedbugs can minimize the risks of bites and infestation of their belongings, and must also do their civic duty to avoid contributing to the subsequent contamination of other hotels and, finally, home. © 2012 International Society of Travel Medicine.

Isolated ionospheric disturbances as deduced from global GPS network

Directory of Open Access Journals (Sweden)

E. L. Afraimovich

2004-01-01

Full Text Available We investigate an unusual class of medium-scale traveling ionospheric disturbances of the nonwave type, isolated ionospheric disturbances (IIDs that manifest themselves in total electron content (TEC variations in the form of single aperiodic negative TEC disturbances of a duration of about 10min (the total electron content spikes, TECS. The data were obtained using the technology of global detection of ionospheric disturbances using measurements of TEC variations from a global network of receivers of the GPS. For the first time, we present the TECS morphology for 170 days in 1998–2001. The total number of TEC series, with a duration of each series of about 2.3h (2h18m, exceeded 850000. It was found that TECS are observed in no more than 1–2% of the total number of TEC series mainly in the nighttime in the spring and autumn periods. The TECS amplitude exceeds the mean value of the "background" TEC variation amplitude by a factor of 5–10 as a minimum. TECS represent a local phenomenon with a typical radius of spatial correlation not larger than 500km. The IID-induced TEC variations are similar in their amplitude, form and duration to the TEC response to shock-acoustic waves (SAW generated during rocket launchings and earthquakes. However, the IID propagation velocity is less than the SAW velocity (800–1000m/s and are most likely to correspond to the velocity of background medium-scale acoustic-gravity waves, on the order of 100–200m/s. Key words. Ionosphere (ionospheric irregularities, instruments and techniques - Radio science (ionospheric propagation

HIV and travel.

Science.gov (United States)

Schuhwerk, M A; Richens, J; Zuckerman, Jane N

2006-01-01

There is a high demand for travel among HIV-positive individual. This demand arises partly from those who have benefited from advances in antiretroviral therapy as well as those with disease progression. The key to a successful and uneventful holiday lies in careful pre-trip planning, yet many patients fail to obtain advice before travelling. Travel advice for HIV patients is becoming increasingly specialized. In addition to advice on common travel-related infectious diseases, HIV-positive travellers are strongly advised to carry information with them and they need specific advice regarding country entry restrictions, HIV inclusive travel insurance, safety of travel vaccinations and highly active antiretroviral therapy-related issues. A wide range of relevant issues for the HIV-positive traveller are discussed in this review and useful websites can be found at the end.

Essential travel medicine

CERN Document Server

Zuckerman, Jane N; Leggat, Peter

2015-01-01

This 1st edition of Essential Travel Medicine provides an excellent concise introduction to the specialty of Travel Medicine. This core text will enable health care practitioners particularly those new to the clinical practice of Travel Medicine, to gain a fundamental understanding of the diverse and complex issues which can potentially affect the health of the many millions of people who undertake international travel. Jane N Zuckerman is joined by Gary W Brunette from CDC and Peter A Leggat from Australia as Editors. Leading international specialists in their fields have contributed authoritative chapters reflecting current knowledge to facilitate best clinical practice in the different aspects of travel medicine. The aim of Essential Travel Medicine is to provide a comprehensive guide to Travel Medicine as well as a fundamental knowledge base to support international undergraduate and postgraduate specialty training programmes in the discipline of Travel Medicine. The 1st edition of Essential Travel ...

A profile of travelers--an analysis from a large swiss travel clinic.

Science.gov (United States)

Bühler, Silja; Rüegg, Rolanda; Steffen, Robert; Hatz, Christoph; Jaeger, Veronika K

2014-01-01

Globally, the Swiss have one of the highest proportions of the population traveling to tropical and subtropical countries. Large travel clinics serve an increasing number of customers with specific pre-travel needs including uncommon destinations and preexisting medical conditions. This study aims to identify health characteristics and travel patterns of travelers seeking advice in the largest Swiss travel clinic so that tailored advice can be delivered. A descriptive analysis was performed on pre-travel visits between July 2010 and August 2012 at the Travel Clinic of the Institute of Social and Preventive Medicine, University of Zurich, Switzerland. A total of 22,584 travelers sought pre-travel advice. Tourism was the main reason for travel (17,875, 81.5%), followed by visiting friends and relatives (VFRs; 1,715, 7.8%), traveling for business (1,223, 5.6%), and "other reasons" (ie, volunteer work, pilgrimage, study abroad, and emigration; 1,112, 5.1%). The main travel destination was Thailand. In the VFR group, the highest proportions of traveling children (258, 15.1%) and of pregnant or breastfeeding women (23, 3.9%) were observed. Mental disorders were more prominent in VFRs (93, 5.4%) and in travel for "other reasons" (63, 5.7%). The latter stayed for the longest periods abroad; 272 (24.9%) stayed longer than 6 months. VFR travelers received the highest percentage of yellow fever vaccinations (523, 30.5%); in contrast, rabies (269, 24.2%) and typhoid vaccinations (279, 25.1%) were given more often to the "other travel reasons" group. New insights into the characteristics of a selected and large population of Swiss international travelers results in improved understanding of the special needs of an increasingly diverse population and, thus, in targeted preventive advice and interventions. © 2014 International Society of Travel Medicine.

Simulation and Observation of Acoustic-Gravity Waves in the Ionosphere

Science.gov (United States)

Kunitsyn, Viacheslav; Andreeva, Elena; Krysanov, Boris; Nesterov, Ivan

Atmospheric and ionospheric perturbations associated with the acoustic-gravity waves (AGW) with typical frequencies of a few hertz -millihertz are considered. These events may be caused by the influence from space and atmosphere as well as by oscillations of the Earth surface and other near-surface phenomena. The surface sources include long-period oscillations of the Earth's surface, earthquakes, explosions, thermal heating, seisches and tsunami waves. The wavelike phenomena manifest themself as travelling disturbances of air (in the atmosphere) and of electron density (in the ionosphere). Travelling ionospheric disturbances (TIDs) are well detected by radio physical methods. AGW generation by near-surface sources is modeled by the numerical solution of the equation of geophysical fluid dynamics for different sources in two-dimensional non-linear dissipative compressible atmosphere. The numerical calculations are based on the FCT (Flux Corrected Transport) technique of the second order accuracy in time and space. Different scenarios of AGW generation are analyzed. The AGW caused by the surface sources within a few hertz-millihertz frequency band appear at the altitudes of middle atmosphere and ionosphere as the disturbances with typical scales from a few kilometers to several hundreds kilometers. Such structures can be successfully monitored by the methods of satellite radio tomography (RT). For the purposes of RT diagnostics of such disturbances, low-orbiting navigational satellites like Transit and Tsikada and high-orbiting navigation systems GPS/GLONASS are used. The results of numerical modeling of AGW generation by the surface sources are compared with the data of RT sounding. Also, generation of AGW by volumetric sources such as particle precipitation, rocket launching, heating by high-frequency radiation and other are considered. The obtained results proved the capability of RT methods of detecting and distinguishing between TIDs caused by AGW generated by

Atmospheric gravity wave detection following the 2011 Tohoku earthquakes combining COSMIC occultation and GPS observations

Science.gov (United States)

Yan, X.; Tao, Y.; Xia, C.; Qi, Y.; Zuo, X.

2017-12-01

Several studies have reported the earthquake-induced atmospheric gravity waves detected by some new technologies such as airglow (Makela et al., 2011), GOCE (Garcia et al., 2013), GRACE (Yang et al., 2014), F3/C radio occultation sounding (Coïsson et al., 2015). In this work, we collected all occultation events on 11 March, and selected four events to analyze at last. The original and filtered podTEC is represented as function of the altitude of the impact parameter and UT of the four events. Then, the travel time diagrams of filtered podTEC derived from the events were analyzed. The occultation signal from one event (marked as No.73) is consistent with the previous results reported by Coïsson. 2015, which is corresponds to the ionospheric signal induced from tsunami gravity wave. What is noticeable, in this work, is that three occultation events of No.403, 77 and 118 revealed a disturbance of atmospheric gravity wave with velocity 300m/s, preceding the tsunami. It would probably be correspond to the gravity waves caused by seismic rupture but not tsunami. In addition, it can be seen that the perturbation height of occultation observation TEC is concentrated at 200-400km, corresponding ionosphere F region. The signals detected above are compared with GPS measurements of TEC from GEONET and IGS. From GPS data, traveling ionospheric disturbances were observed spreading out from the epicenter as a quasi-circular propagation pattern with the time. Exactly, we observed an acoustic wave coupled with Rayleigh wave starting from the epicenter with a speed of 3.0km/s and a superimposed acoustic-gravity wave moving with a speed of 800m/s. The acoustic-gravity wave generated at the epicenter and gradually attenuated 800km away, then it is replaced by a gravity wave coupled with the tsunami that moves with a speed of between 100 and 300m/s. It is necessary to confirm the propagation process of the waves if we attempt to evaluate the use of ionospheric seismology as a

Travelling with HIV

DEFF Research Database (Denmark)

Nielsen, Ulla S; Jensen-Fangel, Søren; Pedersen, Gitte

2014-01-01

BACKGROUND: We aimed to describe travel patterns, extent of professional pre-travel advice and health problems encountered during travel among HIV-infected individuals. METHODS: During a six-month period a questionnaire was handed out to 2821 adult HIV-infected individuals attending any...... of the eight Danish medical HIV care centers. RESULTS: A total of 763 individuals responded. During the previous two years 49% had travelled outside Europe; 18% had travelled less and 30% were more cautious when choosing travel destination than before the HIV diagnosis. Pre-travel advice was sought by only 38......%, and travel insurance was taken out by 86%. However, 29%/74% did not inform the advisor/the insurance company about their HIV status. Nearly all patients on highly active antiretroviral therapy (HAART) were adherent, but 58% worried about carrying HIV-medicine and 19% tried to hide it. Only 19% experienced...

On the 485-day Mode in the Atmospheric Angular Momentum: Spectral Analysis of IERS Data

Science.gov (United States)

Tsurkis, I. Ya.; Kuchai, M. S.

2018-05-01

The modification of spectral analysis especially intended for studying the disturbing functions of the atmosphere and ocean, as well as the observed polar motion (Wiener-Liouville spectrum), is used. The time series of the atmospheric disturbing functions obtained by the U.S. National Centers for Environmental Prediction (NCEP) of the International Earth Rotation and Reference Systems Service (IERS) for the period from January 1, 1980 to June 20, 2014 (http://www.iers.org/.cs1?pid=43-1100116) are analyzed. It is shown that the baric disturbing function contains a regular mode with a period of 16 months; the contribution of this mode in the polar motion is estimated.

Disturbance Hydrology: Preparing for an Increasingly Disturbed Future

Science.gov (United States)

Mirus, Benjamin B.; Ebel, Brian A.; Mohr, Christian H.; Zegre, Nicolas

2017-12-01

This special issue is the result of several fruitful conference sessions on disturbance hydrology, which started at the 2013 AGU Fall Meeting in San Francisco and have continued every year since. The stimulating presentations and discussions surrounding those sessions have focused on understanding both the disruption of hydrologic functioning following discrete disturbances, as well as the subsequent recovery or change within the affected watershed system. Whereas some hydrologic disturbances are directly linked to anthropogenic activities, such as resource extraction, the contributions to this special issue focus primarily on those with indirect or less pronounced human involvement, such as bark-beetle infestation, wildfire, and other natural hazards. However, human activities are enhancing the severity and frequency of these seemingly natural disturbances, thereby contributing to acute hydrologic problems and hazards. Major research challenges for our increasingly disturbed planet include the lack of continuous pre and postdisturbance monitoring, hydrologic impacts that vary spatially and temporally based on environmental and hydroclimatic conditions, and the preponderance of overlapping or compounding disturbance sequences. In addition, a conceptual framework for characterizing commonalities and differences among hydrologic disturbances is still in its infancy. In this introduction to the special issue, we advance the fusion of concepts and terminology from ecology and hydrology to begin filling this gap. We briefly explore some preliminary approaches for comparing different disturbances and their hydrologic impacts, which provides a starting point for further dialogue and research progress.

Receptivity to free stream acoustic disturbances due to a roughness element on a flat plate

OpenAIRE

Ashour, Osama Naim

1993-01-01

The boundary-layer receptivity resulting from acoustic forcing over a flat plate with a surface irregularity is investigated. The unsteady free-stream disturbances couple with the steady perturbations resulting from the surface irregularity to form a traveling-wave mode. The resonance condition necessary for receptivity requires a forcing at a wave number equal to that of the Tollmien-Schlichting (TS) eigenmode and a frequency equal to that of the free-stream acoustic disturban...

The New England travel market: changes in generational travel patterns

Science.gov (United States)

Rodney B. Warnick

1995-01-01

The purpose of this study was to examine and explore the New England domestic travel market trends, from 1979 through 1991 within the context of generations. The existing travel markets, who travel to New England, are changing by age cohorts and specifically within different generations. The New England changes in generational travel patterns do not reflect national...

Atmospheric structure deduced from disturbed line profiles application to Ca II lines

International Nuclear Information System (INIS)

Mein, N.; Mein, P.; Malherbe, J.-M.; Dame, L.; Dumont, S.; CNRS, Laboratoire de Physique Stellaire et Planetaire, Verrieres-le-Buisson, France; College de France, Paris)

1985-01-01

A new method is described in order to derive physical quantities (temperature, pressure, radial velocities) from the observation of disturbed line profiles. A method of Fourier analysis is suggested with double profiles and a nonlinear expansion of the coefficient of the Fourier terms. An application to a sequence of H-Ca II lines is attempted. The method is a powerful tool allowing for the simultaneous determination of at least four physical quantities. 9 references

Detecting Landscape Disturbance at the Nasca Lines Using SAR Data Collected from Airborne and Satellite Platforms

Directory of Open Access Journals (Sweden)

Douglas C. Comer

2017-10-01

Full Text Available We used synthetic aperture radar (SAR data collected over Peru’s Lines and Geoglyphs of the Nasca and Palpa World Heritage Site to detect and measure landscape disturbance threatening world-renowned archaeological features and ecosystems. We employed algorithms to calculate correlations between pairs of SAR returns, collected at different times, and generate correlation images. Landscape disturbances even on the scale of pedestrian travel are discernible in correlation images generated from airborne, L-band SAR. Correlation images derived from C-band SAR data collected by the European Space Agency’s Sentinel-1 satellites also provide detailed landscape change information. Because the two Sentinel-1 satellites together have a repeat pass interval that can be as short as six days, products derived from their data can not only provide information on the location and degree of ground disturbance, but also identify a time window of about one to three weeks during which disturbance must have occurred. For Sentinel-1, this does not depend on collecting data in fine-beam modes, which generally sacrifice the size of the area covered for a higher spatial resolution. We also report on pixel value stretching for a visual analysis of SAR data, quantitative assessment of landscape disturbance, and statistical testing for significant landscape change.

Photokeratitis induced by ultraviolet radiation in travelers: A major health problem

Directory of Open Access Journals (Sweden)

M Izadi

2018-01-01

Full Text Available Ultraviolet (UV irradiation is one of the several environmental hazards that may cause inflammatory reactions in ocular tissues, especially the cornea. One of the important factors that affect how much ultraviolet radiation (UVR humans are exposed to is travel. Hence, traveling is considered to include a more acute UVR effect, and ophthalmologists frequently evaluate and manage the ocular manifestations of UV irradiation, including UV-induced keratitis. The purpose of this paper is to provide an evidence-based analysis of the clinical effect of UVR in ocular tissues. An extensive review of English literature was performed to gather all available articles from the National Library of Medicine PubMed database of the National Institute of Health, the Ovid MEDLINE database, Scopus, and ScienceDirect that had studied the effect of UVR on the eye and its complications, between January 1970 and June 2014. The results show that UVR at 300 nm causes apoptosis in all three layers of the cornea and induces keratitis. Apoptosis in all layers of the cornea occurs 5 h after exposure. The effect of UVR intensity on the eye can be linked to numerous factors, including solar elevation, time of day, season, hemisphere, clouds and haze, atmospheric scattering, atmospheric ozone, latitude, altitude, longitudinal changes, climate, ground reflection, and geographic directions. The most important factor affecting UVR reaching the earth's surface is solar elevation. Currently, people do not have great concern over eye protection. The methods of protection against UVR include avoiding direct sunlight exposure, using UVR-blocking eyewear (sunglasses or contact lenses, and wearing hats. Hence, by identifying UVR intensity factors, eye protection factors, and public education, especially in travelers, methods for safe traveling can be identified.

Photokeratitis induced by ultraviolet radiation in travelers: A major health problem.

Science.gov (United States)

Izadi, M; Jonaidi-Jafari, N; Pourazizi, M; Alemzadeh-Ansari, M H; Hoseinpourfard, M J

2018-01-01

Ultraviolet (UV) irradiation is one of the several environmental hazards that may cause inflammatory reactions in ocular tissues, especially the cornea. One of the important factors that affect how much ultraviolet radiation (UVR) humans are exposed to is travel. Hence, traveling is considered to include a more acute UVR effect, and ophthalmologists frequently evaluate and manage the ocular manifestations of UV irradiation, including UV-induced keratitis. The purpose of this paper is to provide an evidence-based analysis of the clinical effect of UVR in ocular tissues. An extensive review of English literature was performed to gather all available articles from the National Library of Medicine PubMed database of the National Institute of Health, the Ovid MEDLINE database, Scopus, and ScienceDirect that had studied the effect of UVR on the eye and its complications, between January 1970 and June 2014. The results show that UVR at 300 nm causes apoptosis in all three layers of the cornea and induces keratitis. Apoptosis in all layers of the cornea occurs 5 h after exposure. The effect of UVR intensity on the eye can be linked to numerous factors, including solar elevation, time of day, season, hemisphere, clouds and haze, atmospheric scattering, atmospheric ozone, latitude, altitude, longitudinal changes, climate, ground reflection, and geographic directions. The most important factor affecting UVR reaching the earth's surface is solar elevation. Currently, people do not have great concern over eye protection. The methods of protection against UVR include avoiding direct sunlight exposure, using UVR-blocking eyewear (sunglasses or contact lenses), and wearing hats. Hence, by identifying UVR intensity factors, eye protection factors, and public education, especially in travelers, methods for safe traveling can be identified.

Interrelationship of Atmospheric Parameters in Honduras.

Science.gov (United States)

1984-06-01

in the summer is associated with systems known as " temporales " (Portig, 1965; Hastenrath, 1967). These atmospheric disturbances originate over the...Geophys. Biokl., Serie B, 13, 1963a. pp 98-107. Hastenrath, S., "Der Tagesgang von Temperatur und Luftfeuchtigkeit in San Salvador," Geofis. Pura Appl., 56

On the relationship between travel time and travel distance of commuters

NARCIS (Netherlands)

Rietveld, P.; Zwart, A.P.; Wee, van G.P.; Hoorn, van der T.

1999-01-01

This paper gives a detailed empirical analysis of the relationships between different indicators of costs of commuting trips by car: difference as the crow flies, shortest travel time according to route planner, corresponding travel distance, and reported travel time. Reported travel times are

The impact of injection anxiety on education of travelers about common travel risks.

Science.gov (United States)

Noble, Lorraine M; Farquharson, Lorna; O'Dwyer, Niamh A; Behrens, Ron H

2014-01-01

Despite many travelers receiving at least one vaccination during the pre-travel consultation, little is known about travelers' fear of injections and the impact this may have on educating travelers about health risks associated with their trip. This study aimed to investigate: (1) the prevalence of injection anxiety in travelers attending a pre-travel consultation, (2) whether anxiety due to anticipating a vaccination adversely affects recall of information and advice, and (3) whether clinicians can recognize travelers' anxiety, and how they respond to anxious travelers. Consecutive adult travelers (N = 105) attending one of two inner-city travel clinics completed self-report measures of state anxiety, injection anxiety, and symptoms of needle phobia immediately before and after their pre-travel consultation. Clinicians were also asked to rate travelers' anxiety and report any anxiety management strategies. Standardized information was presented during the consultation and recall of information and advice was assessed immediately post-consultation. Delayed recall (24 hours) was assessed for a subsample (20%) of participants. More than one third of travelers reported feeling nervous or afraid when having an injection (39%). Travelers' state anxiety was related to their psychological and physiological reactions to needles, and reduced significantly post-consultation. Recall of information and advice varied, with failure of recall ranging from 2 to 70% across 15 items, and delayed recall being significantly lower. No relationship was found between recall and anxiety. Clinician-rated anxiety moderately correlated with travelers' self-reported anxiety. A significant proportion of travelers experienced injection anxiety when attending the pre-travel consultation, with some travelers reporting symptoms consistent with criteria for Blood Injection Injury phobia. There were important gaps in recall of information and advice about common travel risks. Although no

[The profile of Israeli travelers to developing countries: perspectives of a travel clinic].

Science.gov (United States)

Stienlauf, Shmuel; Meltzer, Eyal; Leshem, Eyal; Rendi-Wagner, Pamela; Schwartz, Eli

2010-09-01

The number of Israeli travelers is increasing, including the number of travelers to developing countries. This study aimed to characterize the profile of Israeli travelers to developing countries. Data regarding demographics, travel destinations, trip duration and the purpose of travel were collected on travelers attending the pre-travel clinic at the Sheba Medical Center during a period of 9 years. Between the dates 1/1/1999 and 31/12/2007, 42,771 travelers presented for consultation at the Sheba Medical Center pre-travel clinic. The average age was 30.8 +/- 13.4 years and 54% of the travelers were males. The female proportion increased from 42% in 1999 to 49% in 2006. There was a steady increase in the number of travelers attending our clinic, except in 2003 (coinciding with the SARS epidemic). Post-army backpackers (20-25 year-old age group) were only 43% of the travelers. Children (60 years) comprised 4.4% and 4.6% of the travelers, respectively. The favorite destinations were Asia (55%), followed by Latin America (27%) and Africa (13%). The distribution of travel destinations varied significantly during the study period. Of note is the sharp decline in travel to Africa following the terrorist attack in Mombassa, Kenya (November 2002). The median trip duration changed during the study period, from 30 to 45 days, between 1999-2004 and 2005-2007 respectively. The majority (87%) of voyagers traveled for pleasure, 6% went for business, and 7% were representatives of governmental organizations. This study found an increasing diversity in the traveler population (more women, more children and older travelers) and more diversity in travel destinations. Disease outbreaks and terrorist attacks had transient negative impacts on the number of travelers.

Contact Frequency, Travel Time, and Travel Costs for Patients with Rheumatoid Arthritis

OpenAIRE

Sørensen, Jan; Linde, Louise; Hetland, Merete Lund

2014-01-01

Objectives. To investigate travel time, and travel cost related to contacts with health care providers for patients with rheumatoid arthritis (RA) during a three-month period. Methods. Patient-reported travel time and travel cost were obtained from 2847 patients with RA. Eleven outpatient clinics across Denmark recruited patients to the study. Data collected included frequency, travel time and travel costs for contacts at rheumatology outpatient clinics, other outpatient clinics, general prac...

Role of solar influences on geomagnetosphere and upper atmosphere

Science.gov (United States)

Kumar Tripathi, Arvind

The Earth's magnetosphere and upper atmosphere can be greatly perturbed by variations in the solar luminosity caused by disturbances on the solar surface. The state of near-Earth space environment is governed by the Sun and is very dynamic on all spatial and temporal scale. The geomagnetic field which protects the Earth from solar wind and cosmic rays is also essential to the evolution of life; its variations can have either direct or indirect effect on human physiology and health state even if the magnitude of the disturbance is small. Geomagnetic disturbances are seen at the surface of the Earth as perturbations in the components of the geomagnetic field, caused by electric currents flowing in the magnetosphere and upper atmosphere. Ionospheric and thermospheric storms also result from the redistribution of particles and fields. Global thermospheric storm winds and composition changes are driven by energy injection at high latitudes. These storm effects may penetrate downwards to the lower thermosphere and may even perturb the mesosphere. Many of the ionospheric changes at mid-latitude can be understood as a response to thermospheric perturbations. The transient bursts of solar energetic particles, often associated with large solar transients, have been observed to have effects on the Earth's middle and lower atmosphere, including the large-scale destruction of polar stratospheric and tropospheric ozone. In the present, we have discussed effect of solar influences on earth's magnetosphere and upper atmosphere that are useful to space weather and global warming, on the basis of various latest studies.

Physics of the Sun's Hot Atmosphere B. N. Dwivedi

Indian Academy of Sciences (India)

an Earth-like planet and its atmosphere (cf., Fig. 1). ... the radiative zone (where energy travels outward by radiation through about 70% of the Sun), and the convection .... (1990) carried out rocket-borne experiments to observe off-limb linewidth.

Challenges to providing pre-travel care for travellers visiting friends and relatives: an audit of a specialist travel medicine clinic.

Science.gov (United States)

Rowe, Kate; Chaves, Nadia; Leder, Karin

2017-09-01

Travellers visiting friends and relatives (VFRs) often have complex pre-travel needs. We identified the characteristics, destinations, vaccinations and pre-travel advice provided to VFRs and compared these with non-VFR travellers. The significant differences we found suggest that future research should focus on improving the uptake of recommended interventions in VFR travellers. © International Society of Travel Medicine, 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Use of acoustic wave travel-time measurements to probe the near-surface layers of the Sun

Science.gov (United States)

Jefferies, S. M.; Osaki, Y.; Shibahashi, H.; Duvall, T. L., Jr.; Harvey, J. W.; Pomerantz, M. A.

1994-01-01

The variation of solar p-mode travel times with cyclic frequency nu is shown to provide information on both the radial variation of the acoustic potential and the depth of the effective source of the oscillations. Observed travel-time data for waves with frequency lower than the acoustic cutoff frequency for the solar atmosphere (approximately equals 5.5 mHz) are inverted to yield the local acoustic cutoff frequency nu(sub c) as a function of depth in the outer convection zone and lower atmosphere of the Sun. The data for waves with nu greater than 5.5 mHz are used to show that the source of the p-mode oscillations lies approximately 100 km beneath the base of the photosphere. This depth is deeper than that determined using a standard mixing-length calculation.

Travel characteristics and risk-taking attitudes in youths traveling to nonindustrialized countries.

Science.gov (United States)

Han, Pauline; Balaban, Victor; Marano, Cinzia

2010-01-01

International travel to developing countries is increasing with rising levels of disposable income; this trend is seen in both adults and children. Risk-taking attitude is fundamental to research on the prevention of risky health behaviors, which can be an indicator of the likelihood of experiencing illness or injury during travel. The aim of this study is to investigate whether risk-taking attitudes of youths are associated with travel characteristics and likelihood of experiencing illness or injury while traveling to nonindustrialized countries. Data were analyzed from the 2008 YouthStyles survey, an annual mail survey gathering demographics and health knowledge, attitudes, and practices of individuals from 9 through 18 years of age. Travelers were defined as respondents who reported traveling in the last 12 months to a destination other than the United States, Canada, Europe, Japan, Australia, or New Zealand. Risk-taking attitude was measured by using a four-item Brief Sensation-Seeking Scale. All p values ≤ 0.05 were considered significant. Of 1,704 respondents, 131 (7.7%) traveled in the last 12 months. Females and those with higher household income were more likely to travel (odds ratio = 1.6,1.1). Of those who traveled, 16.7% reported seeking pretravel medical care, with most visiting a family doctor for that care (84.0%). However, one-fifth of respondents reported illness and injury during travel; of these, 83.3% traveled with their parents. Males and older youths had higher mean sensation-seeking scores. Further, travelers had a higher mean sensation-seeking score than nontravelers. Those who did not seek pretravel medical care also had higher mean sensation-seeking scores (p = 0.1, not significant). Our results show an association between risk-taking attitudes and youth travel behavior. However, adult supervision during travel and parental directives prior to travel should be taken into consideration. Communication messages should emphasize the

Observing Traveling Ionospheric Disturbances Caused by Tsunamis Using GPS TEC Measurements

Science.gov (United States)

Galvan, David A.; Komjathy, Attila; Hickey, Michael; Foster, James; Mannucci, Anthony J.

2010-01-01

Ground-based Global Positioning System (GPS) measurements of ionospheric Total Electron Content (TEC) show variations consistent with atmospheric internal gravity waves caused by ocean tsunamis following two recent seismic events: the American Samoa earthquake of September 29, 2009, and the Chile earthquake of February 27, 2010. Fluctuations in TEC correlated in time, space, and wave properties with these tsunamis were observed in TEC estimates processed using JPL's Global Ionospheric Mapping Software. These TEC estimates were band-pass filtered to remove ionospheric TEC variations with wavelengths and periods outside the typical range of internal gravity waves caused by tsunamis. Observable variations in TEC appear correlated with the tsunamis in certain locations, but not in others. Where variations are observed, the typical amplitude tends to be on the order of 1% of the background TEC value. Variations with amplitudes 0.1 - 0.2 TECU are observable with periods and timing affiliated with the tsunami. These observations are compared to estimates of expected tsunami-driven TEC variations produced by Embry Riddle Aeronautical University's Spectral Full Wave Model, an atmosphere-ionosphere coupling model, and found to be in good agreement in some locations, though there are cases when the model predicts an observable tsunami-driven signature and none is observed. These TEC variations are not always seen when a tsunami is present, but in these two events the regions where a strong ocean tsunami was observed did coincide with clear TEC observations, while a lack of clear TEC observations coincided with smaller tsunami amplitudes. There exists the potential to apply these detection techniques to real-time GPS TEC data, providing estimates of tsunami speed and amplitude that may be useful for early warning systems.

Ionosonde observations of daytime spread F at low latitudes

Science.gov (United States)

Jiang, Chunhua; Yang, Guobin; Liu, Jing; Yokoyama, Tatsuhiro; Komolmis, Tharadol; Song, Huan; Lan, Ting; Zhou, Chen; Zhang, Yuannong; Zhao, Zhengyu

2016-12-01

Spread F on ionograms has been considered to be a phenomenon mainly occurred at nighttime. This study presented a case study of daytime spread F observed by the ionosonde installed at Puer (PUR; 22.7°N, 101.05°E; dip latitude 12.9°N), where daytime spread F that lasted for more than 2 h (about 08:30 LT 10:45 LT) was observed on 14 November 2015. To investigate the possible mechanism, ionograms recorded at PUR and Chiang Mai (18.76°N, 98.93°E; dip latitude 9.04°N) were used in this study. We found that traveling ionospheric disturbances were observed before the occurrence of daytime spread F. Meanwhile, the movement of the peak height of the ionosphere was downward. We suggested that downward vertical neutral winds excited by traveling atmospheric disturbances/atmospheric gravity waves might play a significant role in forming daytime spread F over PUR during geomagnetic storms.

Fellow travellers: Working memory and mental time travel in rodents.

Science.gov (United States)

Dere, Ekrem; Dere, Dorothea; de Souza Silva, Maria Angelica; Huston, Joseph P; Zlomuzica, Armin

2017-03-19

The impairment of mental time travel is a severe cognitive symptom in patients with brain lesions and a number of neuropsychiatric disorders. Whether animals are also able to mentally travel in time both forward and backward is still a matter of debate. In this regard, we have proposed a continuum of mental time travel abilities across different animal species, with humans being the species with the ability to perform most sophisticated forms of mental time travel. In this review and perspective article, we delineate a novel approach to understand the evolution, characteristics and function of human and animal mental time travel. Furthermore, we propose a novel approach to measure mental time travel in rodents in a comprehensive manner using a test battery composed of well-validated and easy applicable tests. Copyright © 2017. Published by Elsevier B.V.

Direct Numerical Simulation of Transition Due to Traveling Crossflow Vortices

Science.gov (United States)

Li, Fei; Choudhari, Meelan M.; Duan, Lian

2016-01-01

Previous simulations of laminar breakdown mechanisms associated with stationary crossflow instability over a realistic swept-wing configuration are extended to investigate the alternate scenario of transition due to secondary instability of traveling crossflow modes. Earlier analyses based on secondary instability theory and parabolized stability equations have shown that this alternate scenario is viable when the initial amplitude of the most amplified mode of the traveling crossflow instability is greater than approximately 0.03 times the initial amplitude of the most amplified stationary mode. The linear growth predictions based on the secondary instability theory and parabolized stability equations agree well with the direct numerical simulation. Nonlinear effects are initially stabilizing but subsequently lead to a rapid growth followed by the onset of transition when the amplitude of the secondary disturbance exceeds a threshold value. Similar to the breakdown of stationary vortices, the transition zone is rather short and the boundary layer becomes completely turbulent across a distance of less than 15 times the boundary layer thickness at the completion of transition.

The Concept of Travel Medicine and the Actual Situation of Travel-Related Illnesses.

Science.gov (United States)

Tunalı, Varol; Turgay, Nevin

2017-06-01

Travel medicine defines all diseases and medical situations that are related to travel. Travel medicine comprises infectious diseases, traumas, altitude sickness, sun burns, embolisms, jet lag, and many more travel-related situations. With the increasing possibility and ease of travel, the number of people who have travelled internationally has exceeded 1.13 billion in 2014, and the revenues of international travel have exceeded 1.25 trillion dollars. With every passing day, international travels are shifting toward the developing countries and to more exotic regions of the world, and travelers tend to be more adventurous and daring, thereby increasing risky behaviors during travels. Traveling plays an important role in transmitting infections such as Zika virus infection, Ebola, avian flu, severe acute respiratory syndrome, Chikungunya, and dengue fever and is the principal reason for the epidemics of these types of infections on a global scale. With this background, we suggest that travel medicine is an important but "neglected" medical discipline as the discipline of Parasitology itself like most parasitic diseases.

Transience after disturbance: Obligate species recovery dynamics depend on disturbance duration.

Science.gov (United States)

Singer, Alexander; Johst, Karin

2017-06-01

After a disturbance event, population recovery becomes an important species response that drives ecosystem dynamics. Yet, it is unclear how interspecific interactions impact species recovery from a disturbance and which role the disturbance duration (pulse or press) plays. Here, we analytically derive conditions that govern the transient recovery dynamics from disturbance of a host and its obligately dependent partner in a two-species metapopulation model. We find that, after disturbance, species recovery dynamics depend on the species' role (i.e. host or obligately dependent species) as well as the duration of disturbance. Host recovery starts immediately after the disturbance. In contrast, for obligate species, recovery depends on disturbance duration. After press disturbance, which allows dynamics to equilibrate during disturbance, obligate species immediately start to recover. Yet, after pulse disturbance, obligate species continue declining although their hosts have already begun to increase. Effectively, obligate species recovery is delayed until a necessary host threshold occupancy is reached. Obligates' delayed recovery arises solely from interspecific interactions independent of dispersal limitations, which contests previous explanations. Delayed recovery exerts a two-fold negative effect, because populations continue declining to even smaller population sizes and the phase of increased risk from demographic stochastic extinction in small populations is prolonged. We argue that delayed recovery and its determinants -species interactions and disturbance duration - have to be considered in biodiversity management. Copyright © 2017 Elsevier Inc. All rights reserved.

Contact frequency, travel time, and travel costs for patients with rheumatoid arthritis

DEFF Research Database (Denmark)

Sørensen, Jan; Linde, Louise; Hetland, Merete Lund

2014-01-01

Objectives. To investigate travel time, and travel cost related to contacts with health care providers for patients with rheumatoid arthritis (RA) during a three-month period. Methods. Patient-reported travel time and travel cost were obtained from 2847 patients with RA. Eleven outpatient clinics...... across Denmark recruited patients to the study. Data collected included frequency, travel time and travel costs for contacts at rheumatology outpatient clinics, other outpatient clinics, general practitioners, privately practicing medical specialists, inpatient hospitals and accident and emergency...... and 13 € on travelling per contact, corresponding to a total of 4.6 hours and 56 € during the 3-month period. There was great variation in patient travel time and costs, but no statistically significant associations were found with clinical and sociodemographic characteristics. Conclusion. The results...

Contact frequency, travel time, and travel costs for patients with rheumatoid arthritis.

Science.gov (United States)

Sørensen, Jan; Linde, Louise; Hetland, Merete Lund

2014-01-01

Objectives. To investigate travel time, and travel cost related to contacts with health care providers for patients with rheumatoid arthritis (RA) during a three-month period. Methods. Patient-reported travel time and travel cost were obtained from 2847 patients with RA. Eleven outpatient clinics across Denmark recruited patients to the study. Data collected included frequency, travel time and travel costs for contacts at rheumatology outpatient clinics, other outpatient clinics, general practitioners, privately practicing medical specialists, inpatient hospitals and accident and emergency departments. Results. Over a 3-month period, patients with RA had on average 4.4 (sd 5.7) contacts with health care providers, of which 2.8 (sd 4.0) contacts were with rheumatology outpatient clinics. Private car and public travel were the most frequent modes of travel. The average patient spent 63 minutes and 13 € on travelling per contact, corresponding to a total of 4.6 hours and 56 € during the 3-month period. There was great variation in patient travel time and costs, but no statistically significant associations were found with clinical and sociodemographic characteristics. Conclusion. The results show that patients with RA spend private time and costs on travelling when they seek treatment. These findings are particularly important when analyzing social costs associated with RA.

Validation of a multimodal travel simulator with travel information provision

NARCIS (Netherlands)

Chorus, C.G.; Molin, E.J.E.; Arentze, T.A.; Hoogendoorn, S.P.; Timmermans, H.J.P.; Wee, van G.P.

2007-01-01

This paper presents a computer based travel simulator for collecting data concerning the use of next-generation ATIS and their effects on traveler decision making in a multimodal travel environment. The tool distinguishes itself by presenting a completely abstract multimodal transport network, where

Do British travel agents provide adequate health advice for travellers?

Science.gov (United States)

Lawlor, D A; Burke, J; Bouskill, E; Conn, G; Edwards, P; Gillespie, D

2000-01-01

Travel-related illness is a burden for primary care, with more than two million travellers consulting a general practitioner each year. The annual cost of travel-related illness in the United Kingdom is 11 million Pounds. Travel agents are in a unique position to influence this burden as the most common and most serious problems are preventable with simple advice and/or immunisation. This study, using covert researchers, suggests this potential is not being fully utilised. PMID:10954940

International Travelers' Sociodemographic, Health, and Travel Characteristics: An Italian Study.

Science.gov (United States)

Troiano, Gianmarco; Mercone, Astrid; Bagnoli, Alessandra; Nante, Nicola

Approximately the 8% of travelers requires medical care, with the diagnosis of a vaccine-preventable disease. The aim of our study was to analyze the socio-demographic, health and travel characteristics of the Italian international travelers. We conducted a cross sectional study from January 2015 to June 2016, at the Travel Medicine Clinic of Siena, asking the doctor to interview patients who attended the Clinic, recording socio-demographic and travel information, malaria prophylaxis, vaccinations. The data were organized in a database and processed by software Stata®. We collected 419 questionnaires. Patients chose 71 countries for their travels; the favorite destinations were: India (6.31%), Thailand (6.31%), and Brazil (5.10%). The mean length of stay was 36.17 days. Italians, students, and freelancers tended to stay abroad for a longer time (mean: 36.4 days, 59.87 days and 64.16 days respectively). 33.17% of our sample used drugs for malaria chemoprophylaxis: 71.9% of them used Atovaquone/Proguanil (Malarone®), 26.6% used Mefloquine (Lariam®), 1.5% other drugs. The vaccinations that travelers mostly got in our study were to prevent hepatitis A (n = 264), the typhoid fever (n = 187), the Tetanus + Diphtheria + Pertussis (n = 165), the Yellow fever (n = 118) and the cholera (n = 78). Twenty-eight (6.68%) refused some recommended vaccinations. The vaccines mostly refused were for Typhoid fever (n = 20), hepatitis a (n = 9), and cholera (n = 9). Our results demonstrated that Italian international travelers are at-risk because of their poor vaccinations adherence. This implies that pre-travel counseling is fundamental to increase the knowledge of the risks and the compliance of future travelers. Copyright © 2016 Icahn School of Medicine at Mount Sinai. Published by Elsevier Inc. All rights reserved.

Travellers' diarrhoea.

Science.gov (United States)

Ericsson, Charles D

2003-02-01

Risk of travellers' diarrhoea is about 7% in developed countries and 20-50% in the developing world. Options for prevention include education and chemoprophylaxis. Vaccination is a promising but incomplete option. Achieving behaviour modification of food and water choices among tourists is difficult. Bismuth subsalicylate (BSS)-containing compounds are about 62% effective in the prevention of travellers' diarrhoea. Antibiotics are about 84% effective in preventing travellers' diarrhoea. Routine prophylaxis of travellers' diarrhoea, especially with antibiotics, should be discouraged. Oral rehydration is generally important in the treatment of diarrhoea, but travellers' diarrhoea is only infrequently dehydrating in adults. The addition of oral rehydration solutions confers no additional benefit to loperamide in the treatment of travellers' diarrhoea in adults. Presently, the most active of the antibiotics routinely available for treatment are members of the fluoroquinolone group. Antibiotics that are not absorbed such as aztreonam and a rifampicin-like agent, rifaximin, are both effective. The latter might become a therapy of choice once it is routinely available, due to predictably less adverse reactions with a non-absorbed antibiotic. Preliminary results with azithromycin look very promising. Less severe disease can be treated with a variety of non-antibiotic agents (e.g. BSS-containing compounds, loperamide and a calmodulin inhibitor, zaldaride). The combination of an antibiotic and loperamide is superior to treatment with either agent alone in a several studies and is arguably the treatment of choice for distressing travellers' diarrhoea.

THE DECISION MAKING OF BUSINESS TRAVELLERS IN SELECTING ONLINE TRAVEL PORTALS FOR TRAVEL BOOKING: AN EMPIRICAL STUDY OF DELHI NATIONAL CAPITAL REGION, INDIA

Directory of Open Access Journals (Sweden)

Bivek DATTA

2018-05-01

Full Text Available The purpose of this paper is to understand the decision making pattern of the Business Travellers in Delhi National Capital Region in India while booking their trips through Online Travel Portals. The study revolves around purchase decision pattern of Business Travellers by investigating their travel decision making style in selecting online travel portals for their trip booking. The authors have adopted the quantitative methodology to achieve the objective of the study. The study is confined purely to the Business Travellers who book their travel through online travel portals. The data was collected through a structured questionnaire. 300 Business Travellers were interviewed at the departure lounge of Indira Gandhi International Airport, New Delhi, India out of which 150 questionnaires were incomplete in many respects and could not be used and only 150 questionnaires were usable resulting in the response rate of 50%. The Analytical Hierarchy process method was adopted to analyze the relative weights assigned by Business Travellers. The present study identifies through literature review the nine fundamental values of internet purchase i.e. product quality, cost, time to receive the product, convenience, time spent, confidentiality, shopping enjoyment, security and environmental impact. The research findings indicate that business travellers value confidentiality, security and product quality the most while choosing the Online Travel Portal to book their trip. The study is primarily centered on the consumer typology approach to study the decision making patterns of business travellers whereas there are other variables such as lifestyle, personality, attitude which can also be investigated. The study is only restricted to Business Travellers decision making pattern pertaining to their travel booking whereas a study can also be undertaken on leisure travellers decision making pattern. The study is restricted to only Delhi National Capital Region

The Tourist Itinerary Travel Loop: historical and contemporary travel characteristics

OpenAIRE

Lundgren, Jan O.

2012-01-01

In today’s tourist travel, the travel loop represents a very popular itinerary design, although the circumstances under which it is applied, as well as its geographic scale, often differ from the grandiose loop designs of centuries past. During the past couple of decades, a popular kind of new travel has emerged, the cruise-ship travel phenomenon, which often is arranged as quite an extensive itinerary loop. . However, the cruises can also be transoceanic, even global, with the tourist flying...

Contact Frequency, Travel Time, and Travel Costs for Patients with Rheumatoid Arthritis

Directory of Open Access Journals (Sweden)

Jan Sørensen

2014-01-01

Full Text Available Objectives. To investigate travel time, and travel cost related to contacts with health care providers for patients with rheumatoid arthritis (RA during a three-month period. Methods. Patient-reported travel time and travel cost were obtained from 2847 patients with RA. Eleven outpatient clinics across Denmark recruited patients to the study. Data collected included frequency, travel time and travel costs for contacts at rheumatology outpatient clinics, other outpatient clinics, general practitioners, privately practicing medical specialists, inpatient hospitals and accident and emergency departments. Results. Over a 3-month period, patients with RA had on average 4.4 (sd 5.7 contacts with health care providers, of which 2.8 (sd 4.0 contacts were with rheumatology outpatient clinics. Private car and public travel were the most frequent modes of travel. The average patient spent 63 minutes and 13 € on travelling per contact, corresponding to a total of 4.6 hours and 56 € during the 3-month period. There was great variation in patient travel time and costs, but no statistically significant associations were found with clinical and sociodemographic characteristics. Conclusion. The results show that patients with RA spend private time and costs on travelling when they seek treatment. These findings are particularly important when analyzing social costs associated with RA.

Remote sensing of traveling ionospheric disturbances resulting from underground nuclear tests

International Nuclear Information System (INIS)

Copenhaver, C.

1985-01-01

Following an underground nuclear test, an acoustic pulse propagates upward through the atmosphere and sets the ionosphere in motion which, in turn, generates gravity waves. The usual ionospheric monitoring approach is to use a phase sounder to observe the acoustic pulse. However, there are other detection techniques that can be employed. These detection techniques include the use of a low-frequency filter so that only long period (approximately 10 minutes) gravity waves can be observed. Another detection technique is to correlate microbarographic measurements on the surface with HF sounder data from the ionosphere to measure Lamb waves. A third detection technique is to correlate seismometer measurements in the ground with their corresponding ionospheric perturbations. The theoretical and experimental aspects of these remote detection techniques are discussed here

On the relationship between travel time and travel distance in the Netherlands

NARCIS (Netherlands)

Rietveld, P.; Zwart, B.; van Wee, B.; van der Hoorn, A.I.J.M.

1999-01-01

This paper gives a detailed empirical analysis of the relationships between different indicators of costs of commuting trips by car: difference as the crow flies, shortest travel time according to route planner, corresponding travel distance, and reported travel time. Reported travel times are

Trends and characteristics among HIV-infected and diabetic travelers seeking pre-travel advice.

Science.gov (United States)

Elfrink, Floor; van den Hoek, Anneke; Sonder, Gerard J B

2014-01-01

The number of individuals with a chronic disease increases. Better treatment options have improved chronic patients' quality of life, likely increasing their motivation for travel. This may have resulted in a change in the number of HIV-infected travelers and/or travelers with Diabetes Mellitus (DM) visiting our travel clinic. We retrospectively analyzed the database of the travel clinic of the Public Health Service Amsterdam, between January 2001 and December 2011 and examined the records for patients with these conditions. Of the 25,000 travelers who consult our clinic annually, the proportion of travelers with HIV or DM has increased significantly. A total of 564 HIV-infected travelers visited our clinic. The mean age was 41 years, 86% were male, 43% visited a yellow fever endemic country and 46.5% had a CD4 count Travelers with low CD4 counts traveled significantly more often to visit friends or relatives. A total of 3704 diabetics visited our clinic. The mean age was 55 years, 52% were male, 27% visited a yellow fever endemic country and 36% were insulin-dependent. Insulin-dependent diabetics traveled more often for work than non-insulin-dependent diabetics. Adequately trained and qualified travel health professionals and up-to-date guidelines for travelers with chronic diseases are of increasing importance. Copyright © 2013 Elsevier Ltd. All rights reserved.

Travelers' health problems and behavior: prospective study with post-travel follow-up.

Science.gov (United States)

Vilkman, Katri; Pakkanen, Sari H; Lääveri, Tinja; Siikamäki, Heli; Kantele, Anu

2016-07-13

The annual number of international tourist arrivals has recently exceeded one billion, yet surprisingly few studies have characterized travelers' behavior, illness, and risk factors in a prospective setting. Particularly scarce are surveys of data spanning travel, return, and follow-up of the same cohort. This study examines behavior and illness among travelers while abroad, after return home, and at follow-up. Patterns of behavior connected to type of travel and illness are characterized so as to identify risk factors and provide background data for pre-travel advice. Volunteers to this prospective cohort study were recruited at visits to a travel clinic prior to departure. Data on the subjects' health and behavior were collected by questionnaires before and after journeys and over a three-week follow-up. In addition, the subjects were asked to fill in health diaries while traveling. The final study population consisted of 460 subjects, 79 % of whom reported illness during travel or on arrival: 69 % had travelers' diarrhea (TD), 17 % skin problems, 17 % fever, 12 % vomiting, 8 % respiratory tract infection, 4 % urinary tract infection, 2 % ear infection, 4 % gastrointestinal complaints other than TD or vomiting, and 4 % other symptoms. Of all subjects, 10 % consulted a doctor and 0.7 % were hospitalized; 18 % took antimicrobials, with TD as the most common indication (64 %). Ongoing symptoms were reported by 25 % of all travelers upon return home. During the three-week follow-up (return rate 51 %), 32 % of respondents developed new-onset symptoms, 20 % visited a doctor and 1.7 % were hospitalized. Factors predisposing to health problems were identified by multivariable analysis: certain regions (Southern Asia, South-Eastern Asia, and Eastern Africa), female gender, young age, and long travel duration. Despite proper preventive measures like vaccinations, malaria prophylaxis, and travel advice, the majority of our subjects fell ill during or

78 FR 73702 - Federal Travel Regulation (FTR); Telework Travel Expenses Test Programs

Science.gov (United States)

2013-12-09

...; Docket Number 2013-0012, Sequence 1] RIN 3090-AJ23 Federal Travel Regulation (FTR); Telework Travel...). ACTION: Final rule. SUMMARY: GSA is amending the Federal Travel Regulation (FTR) to incorporate the Telework Enhancement Act of 2010, which establishes and authorizes telework travel expenses test programs...

International travel and vaccinations.

OpenAIRE

Rizvon, M K; Qazi, S; Ward, L A

1999-01-01

With the increase in global travel, no disease is beyond the reach of any population. Traveling patients should be advised to follow food and water precautions and encouraged to receive the recommended immunizations. Travel medicine plays a vital role not only in limiting the morbidity of travel-related illnesses but also in limiting the spread of diseases. This article addresses the common issues related to travel, reviews the care of the immunocompromised traveler, and updates the available...

Linear and nonlinear development of controlled disturbances in the supersonic boundary layer on a swept wing at Mach 2.5

International Nuclear Information System (INIS)

Kolosov, G L; Kosinov, A D

2016-01-01

Experimental data on the linear and nonlinear wave train development in 3D supersonic boundary layer over a 45° swept-wing at Mach number 2.5 are presented. Travelling artificial disturbances were introduced in the boundary layer by periodical glow discharge at frequencies 10 and 20 kHz. The spatial-temporal and spectral-wave characteristics of the wave train of unstable disturbances in the linear region are obtained. It is shown that the additional peaks in β '-spectra arise for both subharmonic and fundamental frequencies. The experiments indicate the presence of subharmonic resonance mechanism in 3D boundary layer at Mach number 2.5. (paper)

Risk factors and pre-travel healthcare of international travellers attending a Dutch travel clinic: a cross-sectional analysis

NARCIS (Netherlands)

Wieten, Rosanne W.; van der Schalie, Maurice; Visser, Benjamin J.; Grobusch, Martin P.; van Vugt, Michèle

2014-01-01

The number of international travellers is currently estimated to exceed one billion annually. To address travel related health risks and facilitate risk reduction strategies, detailed knowledge of travellers' characteristics is important. In this cross-sectional study, data of a 20% sample of

Danish travel activities: do we travel more and longer – and to what extent?

DEFF Research Database (Denmark)

Knudsen, Mette Aagaard

Two separate Danish National travel surveys are analysed to outline the amount and extent of national and international travelling during the latest 15-20 years; the national travel survey (TU) describes mainly national daily travel activities, whereas the holiday and business travel survey...... describes national and international travel activities including overnight stay(s). When sampling only respondents with trips above 100 kilometres, they only accounts for around 2% of all daily travel activities, however, this share appears to increase and suggest in general that we do travel longer....... But due to this limited share of trips, the overall impacts of longer distance travelling vanish when considering all daily travel activities. Especially as about 95% of all daily travel destinations range less than 50 kilometres away and in total induce an average trip length of 20 kilometres. If focus...

Travel agents and the prevention of health problems among travelers in Québec.

Science.gov (United States)

Provost, Sylvie; Gaulin, Colette; Piquet-Gauthier, Blandine; Emmanuelli, Julien; Venne, Sylvie; Dion, Réjean; Grenier, Jean-Luc; Dessau, Jean-Claude; Dubuc, Martine

2002-01-01

Among the factors influencing travelers to seek preventive health advice before departure, the travel agent's recommendation plays an important role. The objective of our study was to document the practices and needs of travel agents in Québec (Canada) in relation to the prevention of health problems among travelers. In June 2000, a cross-sectional descriptive survey was carried out among travel agents from all travel agencies in Québec. One agent per agency was asked to answer our questions. Data were collected using a 32-item telephone questionnaire. Altogether, 708 travel agents from the 948 agencies contacted answered our questionnaire (participation rate: 75%). Most respondents (81%) believed that the travel agent has a role to play in the prevention of health problems among travelers, especially to recommend that travelers consult a travel clinic before departure. Although over 80% of the agents interviewed mentioned recommending a visit to a travel clinic before an organized tour to Thailand or a backpacking trip in Mexico, less than half said they make the same recommendation for a stay in a seaside resort in Mexico. The majority of respondents were acquainted with the services offered in travel health clinics, and these clinics were the source of travel health information most often mentioned by travel agents. However, nearly 60% of the agents questioned had never personally consulted a travel clinic. When asked about the best way to receive information about travelers' health, more than 40% of respondents favoured receiving information newsletters from public health departments regularly whereas 28% preferred the Internet. Despite the limits of this study, our results should help the public health network better target its interventions aimed to inform travel agents on prevention of health problems among travelers.

German travelers' preferences for travel vaccines assessed by a discrete choice experiment.

Science.gov (United States)

Poulos, Christine; Curran, Desmond; Anastassopoulou, Anastassia; De Moerlooze, Laurence

2018-02-08

Many travelers to regions with endemic infectious diseases do not follow health authorities' recommendations regarding vaccination against vaccine-preventable infectious diseases, before traveling. The determinants of individual travelers' decisions to vaccinate before traveling are largely unknown. This study aimed to provide this information using a discrete choice experiment (DCE) administered to four types of German travelers: (1) business travelers; (2) travelers visiting friends and relatives (VFR); (3) leisure travelers; and (4) backpackers. A DCE survey was developed, pretested and administered online. It included a series of choice questions in which respondents chose between two hypothetical vaccines, each characterized by four disease attributes with varying levels describing the of risk, health impact, curability and transmissibility of the disease they would prevent (described with four disease attributes with varying levels of risk, health impact, curability and transmissibility), and varying levels of four vaccine attributes (duration of protection, number of doses required, time required for vaccination, and vaccine cost). A random-parameters logit model was used to estimate the importance weights each traveler type placed on the various attribute levels. These weights were used to calculate mean monetary equivalents (MMEs) of changes in each attribute (holding all others constant) and of hypothetical disease-vaccine combinations. All traveler types' choices indicated that they attached the greatest importance to the risk and health impact of disease and to the vaccine cost whereas the other disease and vaccine attributes were less important for their decisions about travel vaccines. An option of not choosing any of the vaccine-pairs presented was rarely selected indicating that travelers' generally prefer to be vaccinated rather than not. The MMEs of changes in vaccine attributes indicated a very high variability between the individual travelers

Numerical and experimental study of disturbance wave development in vertical two-phase annular flow

Science.gov (United States)

Hewitt, Geoffrey; Yang, Junfeng; Zhao, Yujie; Markides, Christos; Matar, Omar

2013-11-01

The annular flow regime is characterized by the presence of a thin, wavy liquid film driven along the wall by the shear stress exerted by the gas phase. Under certain liquid film Reynolds numbers, large disturbance waves are observed to traverse the interface, whose length is typically on the order of 20 mm and whose height is typically on the order of 5 times the thickness of the thin (substrate) layer between the waves. Experimental wok has been conducted to study the disturbance wave onset by probing the local film thickness for different Reynolds numbers. It is observed the disturbance waves grow gradually from wavy initiation and form the ring-like structure. To predict the wavy flow field observed in the experiment, 3D CFD simulations are performed using different low Reynolds number turbulence models and Large Eddy Simulation. Modeling results confirm that there is recirculation within the waves, and that they as a packet of turbulence traveling over a laminar substrate film. We also predict the coalescence and the break-up of waves leading to liquid droplet entrainment into the gas core. Skolkovo Foundation, UNIHEAT project.

What proportion of international travellers acquire a travel-related illness? A review of the literature.

Science.gov (United States)

Angelo, Kristina M; Kozarsky, Phyllis E; Ryan, Edward T; Chen, Lin H; Sotir, Mark J

2017-09-01

As international travel increases, travellers may be at increased risk of acquiring infectious diseases not endemic in their home countries. Many journal articles and reference books related to travel medicine cite that between 22-64% of international travellers become ill during or after travel; however, this information is minimal, outdated and limited by poor generalizability. We aim to provide a current and more accurate estimate of the proportion of international travellers who acquire a travel-related illness. We identified studies via PubMed or travel medicine experts, published between January 1, 1976-December 31, 2016 that included the number of international travellers acquiring a travel-related illness. We excluded studies that focused on a single disease or did not determine a rate based on the total number of travellers. We abstracted information on traveller demographics, trip specifics, study enrollment and follow-up and number of ill travellers and their illnesses. Of 743 studies, nine met the inclusion criteria. The data sources were from North America (four studies) and Europe (five studies). Most travellers were tourists, the most frequent destination regions were Asia and Africa, and the median trip duration ranged from 8-21 days. Six studies enrolled participants at the travellers' pre-travel consultation. All studies collected data through either extraction from the medical record, weekly diaries, or pre- and post-travel questionnaires. Data collection timeframes varied by study. Between 6-87% of travellers became ill across all studies. Four studies provided the best estimate: between 43-79% of travellers who frequently visited developing nations (e.g. India, Tanzania, and Kenya) became ill; travellers most frequently reported diarrhoea. This is the most comprehensive assessment available on the proportion of international travellers that develop a travel-related illness. Additional cohort studies would provide needed data to more precisely

Inter-temporal variation in the travel time and travel cost parameters of transport models

OpenAIRE

Börjesson, Maria

2012-01-01

The parameters for travel time and travel cost are central in travel demand forecasting models. Since valuation of infrastructure investments requires prediction of travel demand for future evaluation years, inter-temporal variation of the travel time and travel cost parameters is a key issue in forecasting. Using two identical stated choice experiments conducted among Swedish drivers with an interval of 13 years, 1994 and 2007, this paper estimates the inter-temporal variation in travel time...

The quantified self during travel: mapping health in a prospective cohort of travellers.

Science.gov (United States)

Farnham, Andrea; Furrer, Reinhard; Blanke, Ulf; Stone, Emily; Hatz, Christoph; Puhan, Milo A

2017-09-01

Travel medicine research has remained relatively unchanged in the face of rapid expansion of international travel and is unlikely to meet health challenges beyond infectious diseases. Our aim was to identify the range of health outcomes during travel using real-time monitoring and daily reporting of health behaviours and outcomes and identify traveller subgroups who may benefit from more targeted advice before and during travel. We recruited a prospective cohort of travellers ≥ 18 years and planning travel to Thailand for travel clinics in Zurich and Basel (Switzerland). Participants answered demographic, clinical and risk behaviour questionnaires pre-travel and a daily health questionnaire each day during travel using a smartphone application. Environmental and location data were collected passively by GPS. Classification trees were used to identify predictors of health behaviour and outcomes during travel. Non-infectious disease events were relatively common, with 22.7% (17 out of 75 travellers) experiencing an accident, 40.0% ( n  = 30) a wound or cut and 14.7% ( n  = 11) a bite or lick from an animal. Mental health associated events were widely reported, with 80.0% ( n  = 60) reporting lethargy, 34.7% ( n  = 26) anxiety and 34.7% ( n  = 26) feeling tense or irritable. Classification trees identified age, trip length, previous travel experience and having experienced a sports injury in the past year as the most important discriminatory variables for health threats. Our study offers a revolutionary look at an almost real-time timeline of health events and behaviours during travel using mHealth technology. Non-infectious disease related health issues were common in this cohort, despite being largely unaddressed in traditional travel medicine research and suggest a substantial potential for improving evidence-based travel medicine advice. © International Society of Travel Medicine, 2017. Published by Oxford University Press. All rights

Travel health prevention.

Science.gov (United States)

Korzeniewski, Krzysztof

All around the world there has been a rapid growth in the number of international travels. According to the World Tourism Organisation the number of international tourist arrivals reached 1,235 billion in 2016 and continues to grow at a high rate. This has been much due to the development of air transport (including low-cost airlines), increasingly common economic migration, a growing number of travellers visiting friends and relatives, and an increase in medical tourism. With tropical destinations becoming increasingly popular among travellers, doctors have seen a rising number of patients who seek medical advice on health risks prevalent in hot countries and health prevention measures to be taken in tropical destinations, especially where sanitation is poor. The risk for developing a medical condition while staying abroad depends on a variety of factors, including the traveller's general health condition, health prevention measures taken before or during travel (vaccinations, antimalarial chemoprophylaxis, health precautions during air, road and sea travel, proper acclimatisation, prevention of heat injuries, protection against local flora and fauna, personal hygiene, water, food and feeding hygiene), as well as the prevalence of health risk factors in a given location. Health prevention is a precondition for safe travel and maintaining good physical health; in the era of a rapid growth in international tourism it has become of key importance for all travellers.

Towards More Responsible Business Travel : Green Travel Guide for Business Travellers

OpenAIRE

Aila, Anu

2010-01-01

The purpose of this research type thesis is to find ways how to develop sustainability in business travel. The target is increase the level of understanding and knowledge to respect natural environment and local cultures and find the right channels and ways to raise the knowledge. The study has been done to raise the awareness how business travel can be more sustainable. This thesis analyzes sustainable tourism based on the economic, environmental, and socio-cultural considerations. Green...

Ionospheric disturbances due to underground nuclear explosions and other sources: an elementary discussion, Part I

International Nuclear Information System (INIS)

Wouters, L.F.

1971-01-01

The possible effect of verticle ground surface motion on the ionosphere, as a consequence of acoustic propagation, is discussed. Estimates of R. F. phase path perturbations are developed for several representative sources and several propagative modes (both terrestrial and atmospheric). In particular, amplitude models for ionospheric density perturbations are used. The discrimination of earth quakes and nuclear explosive disturbances is considered and some detailed properties of the extended atmosphere are described. A list of references is provided. (U.S.)

Travel risk behaviors as a determinants of receiving pre-travel health consultation and prevention.

Science.gov (United States)

Shady, Ibrahim; Gaafer, Mohammed; Bassiony, Lamiaa

2015-01-01

An estimated 30-60 % of travelers experience an illness while traveling. The incidence of travel-related illness can be reduced by preventive measures such as those provided by the Traveler Health Clinic (THC) in Kuwait. The present study is an analytical comparative study between groups of travelers visiting the THC during the study period (May 2009 - December 2010) and an age- and gender-matched control group of non-visitors (800 people). Both groups completed a modified pre-departure questionnaire. Bivariate analysis revealed that Kuwaitis (68.2 %), those traveling for work (25.3 %) or leisure (59.5 %), those living in camps (20.4 %) or hotels (64.0 %), and those with knowledge of the THC from the media (28.1 %) or other sources (57.3 %), were more likely to be associated with a high frequency of visits to the THC ( p  travelers heading to Africa (47 %) and South America (10 %) visited the THC more than did others ( P  travel, duration of stay, and choice of travel destination are independent predictors of receiving pre-travel consultation from the THC. Nationality, purpose of travel, length of stay, and travel destination are predictors for receiving a pre-travel consultation from the THC.

Pre-travel care for immunocompromised and chronically ill travellers: A retrospective study.

Science.gov (United States)

van Aalst, Mariëlle; Verhoeven, Roos; Omar, Freshta; Stijnis, Cornelis; van Vugt, Michèle; de Bree, Godelieve J; Goorhuis, Abraham; Grobusch, Martin P

2017-09-01

Immunocompromised and chronically ill travellers (ICCITs) are susceptible to travel related diseases. In ICCITs, pre-travel care regarding vaccinations and prophylactics is complex. We evaluated the protection level by preventive measures in ICCITs by analysing rates of vaccination protection, antibody titres, and the prescription of standby antibiotics. We analysed, and reported according to STROBE guidelines, pre-travel care data for ICCITs visiting the medical pre-travel clinic at the Academic Medical Centre, The Netherlands from 2011 to 2016. We analysed 2104 visits of 1826 ICCITs. Mean age was 46.6 years and mean travel duration 34.5 days. ICCITs on immunosuppressive treatment (29.7%), HIV (17.2%) or diabetes mellitus (10.2%) comprised the largest groups. Most frequently visited countries were Suriname, Indonesia, and Ghana. Most vaccination rates were >90%. Of travellers in high need of hepatitis A and B protection, 56.6 and 75.7%, underwent titre assessments, respectively. Of ICCITs with a respective indication, 50.6% received a prescription for standby antibiotics. Vaccination rates in our study population were overall comparable to those of healthy travellers studied previously in our centre. However, regarding antibody titre assessments and prescription of standby antibiotics, this study demonstrates that uniform pre-travel guidelines for ICCITs are highly needed. Copyright © 2017 Elsevier Ltd. All rights reserved.

25 CFR 700.533 - Restrictions affecting travel and travel expense reimbursement.

Science.gov (United States)

2010-04-01

... having or seeking business with the Commission. (d) Commission employees traveling on official business, as well as employees traveling on personal business, may not accept the use of private airplanes... official business, provided administrative procedures have been followed in making the travel arrangements. ...

The role of forest disturbance in global forest mortality and terrestrial carbon fluxes

Science.gov (United States)

Pugh, Thomas; Arneth, Almut; Smith, Benjamin; Poulter, Benjamin

2017-04-01

Large-scale forest disturbance dynamics such as insect outbreaks, wind-throw and fires, along with anthropogenic disturbances such as logging, have been shown to turn forests from carbon sinks into intermittent sources, often quite dramatically so. There is also increasing evidence that disturbance regimes in many regions are changing as a result of climatic change and human land-management practices. But how these landscape-scale events fit into the wider picture of global tree mortality is not well understood. Do such events dominate global carbon turnover, or are their effects highly regional? How sensitive is global terrestrial carbon exchange to realistic changes in the occurrence rate of such disturbances? Here, we combine recent advances in global satellite observations of stand-replacing forest disturbances and in compilations of forest inventory data, with a global terrestrial ecosystem model which incorporates an explicit representation of the role of disturbance in forest dynamics. We find that stand-replacing disturbances account for a fraction of wood carbon turnover that varies spatially from less than 5% in the tropical rainforest to ca. 50% in the mid latitudes, and as much as 90% in some heavily-managed regions. We contrast the size of the land-atmosphere carbon flux due to this disturbance with other components of the terrestrial carbon budget. In terms of sensitivity, we find a quasi log-linear relationship of disturbance rate to total carbon storage. Relatively small changes in disturbance rates at all latitudes have marked effects on vegetation carbon storage, with potentially very substantial implications for the global terrestrial carbon sink. Our results suggest a surprisingly small effect of disturbance type on large-scale forest vegetation dynamics and carbon storage, with limited evidence of widespread increases in nitrogen limitation as a result of increasing future disturbance. However, the influence of disturbance type on soil carbon

Wintertime westward-traveling planetary-scale perturbations over the Euro-Atlantic region

Energy Technology Data Exchange (ETDEWEB)

Doblas-Reyes, F.J. [Centro de Astrobiologia, INTA, Madrid (Spain); Pastor, M.A.; Casado, M.J. [Instituto Nacional de Meteorologia, Madrid (Spain); Deque, M. [CNRM, Meteo-France, Toulouse (France)

2001-07-01

The features of the wintertime westward-traveling planetary scale perturbations over the Euro-Atlantic region are examined through the use of space-time spectral analysis applied to the 500 hPa geopotential height field. The intention is to understand the nature of these phenomena and the performance of climate models. Data from both ECMWF re-analyses and a simulation from the ARPEGE general circulation model are used. Westward-traveling planetary scale transients are found over the region as local perturbations resembling Rossby normal modes, with a maximum power over the Eastern Atlantic. The westward-traveling planetary scale transients north of 40 {sup circle} N have periods larger than 20 days. South of this latitude, wave periods are shifted to a band around 10 days, so that they can be related to subtropical transient waves. The atmospheric model used, like other models which exhibit reasonable mean climatic properties, tend to have less overall intraseasonal variability than observed. Nevertheless, the model is able to capture most of the features of the westward-traveling low-frequency transients. The differences in basic state, partially produced by scale interactions, would lead to the generation of westward-traveling waves in the model distinct from the observed. However, it is suggested that the improvement of the present model version with regard to previous model versions is due to a better simulation of the time-mean state. The reasonable simulation of the synoptic-scale variability south of 50 {sup circle} N, and thus of its barotropic forcing on the basic state, may also help to explain the realistic westward-traveling transients in the model. (orig.)

The response of a turbulent boundary layer to a small-amplitude traveling wave

International Nuclear Information System (INIS)

Howes, F.A.

1986-01-01

We study the response of a turbulent boundary layer to an outer-flow disturbance in the form of a small-amplitude wave travelling along the bottom of a smooth channel. In a previous paper we proposed a model for the viscous attenuation of a wave propagating along the interface between two superposed fluids inside a laminar boundary layer attached to the bottom wall. We obtained precise estimates on the amount of attenuation suffered by the oscillatory component of the motion as a result of viscous dissipation. This was accomplished by means of a representation of the solution as the asymptotic sum of a Blasius boundary layer profile and a modified Stokes layer profile. The present paper contains a similar asymptotic decomposition of the solution of the appropriate turbulent Prandtl equations when the outer flow is a small-amplitude travelling wave, and so it may be considered an extension of our previous work to the more realistic case of turbulent flow. 4 refs

Characteristics of atmospheric gravity waves observed using the MU (Middle and Upper atmosphere) radar and GPS (Global Positioning System) radio occultation.

Science.gov (United States)

Tsuda, Toshitaka

2014-01-01

The wind velocity and temperature profiles observed in the middle atmosphere (altitude: 10-100 km) show perturbations resulting from superposition of various atmospheric waves, including atmospheric gravity waves. Atmospheric gravity waves are known to play an important role in determining the general circulation in the middle atmosphere by dynamical stresses caused by gravity wave breaking. In this paper, we summarize the characteristics of atmospheric gravity waves observed using the middle and upper atmosphere (MU) radar in Japan, as well as novel satellite data obtained from global positioning system radio occultation (GPS RO) measurements. In particular, we focus on the behavior of gravity waves in the mesosphere (50-90 km), where considerable gravity wave attenuation occurs. We also report on the global distribution of gravity wave activity in the stratosphere (10-50 km), highlighting various excitation mechanisms such as orographic effects, convection in the tropics, meteorological disturbances, the subtropical jet and the polar night jet.

Travelling or not?

DEFF Research Database (Denmark)

Helles, Rasmus; Lai, Signe Sophus

2017-01-01

-12) travelling to multiple countries on several continents. The article shows that there are systematic differences in terms of formal characteristics, themes, and characters’ communicative style between the series that travel and the series that do not. Especially, the analysis finds that the presence of strong...... female lead characters is systematically linked to the positive travel patterns of the series, and that this cuts across different genres of series. The analysis also finds that series, which have explicitly low production values and simple narrative structure, systematically travels poorer....

Health risks, travel preparation, and illness among public health professionals during international travel.

Science.gov (United States)

Balaban, Victor; Warnock, Eli; Ramana Dhara, V; Jean-Louis, Lee Ann; Sotir, Mark J; Kozarsky, Phyllis

2014-01-01

Few data currently exist on health risks faced by public health professionals (PHP) during international travel. We conducted pre- and post-travel health surveys to assess knowledge, attitudes, and practices (KAP), and illnesses among PHP international travelers. Anonymous surveys were completed by PHP from a large American public health agency who sought a pre-travel medical consult from September 1, 2009, to September 30, 2010. Surveys were completed by 122 participants; travelers went to 163 countries. Of the 122 respondents, 97 (80%) reported at least one planned health risk activity (visiting rural areas, handling animals, contact with blood or body fluids, visiting malarious areas), and 50 (41%) reported exposure to unanticipated health risks. Of the 62 travelers who visited malarious areas, 14 (23%) reported inconsistent or no use of malaria prophylaxis. Illness during travel was reported by 33 (27%) respondents. Most of the PHP travelers in our study reported at least one planned health risk activity, and almost half reported exposure to unanticipated health risks, and one-quarter of travelers to malarious areas reported inconsistent or no use of malaria chemoprophylaxis. Our findings highlight that communication and education outreach for PHP to prevent travel-associated illnesses can be improved. Published by Elsevier Ltd.

Effect of Rainfall on Travel Time and Accuracy of Travel Time prediction with rainfall

OpenAIRE

CHUNG, E; EL-FAOUZI, NE; KUWAHARA, M

2007-01-01

Travel time is an important parameter to report to travelers. From the user's perspective, accurate predictions and an estimate of their precision are more beneficial than the current travel time since conditions may change significantly before a traveler completes the journey. Past researches have developed travel time prediction models without considering accidents and rain. Normally accident and Rain may cause to increase travel time. Therefore, it may be interesting to consider Rain and a...

Business Model Development for travel agency : Case company - Goh Travel Korea

OpenAIRE

Manuilova, Mariia

2016-01-01

Millions of tourists visit South Korea every year to experience the culture and a different life style. Moreover, due to economic development, the country has become popular as a study and work destination. As the tourism market is growing, there are many opportunities for travel agencies to find niches in the market. The purpose of this study is to develop a business model for Goh travel Korea – a travel agency for foreign low budget travelers around Korea, to make it more efficient and incr...

Disturbance of a rare seabird by ship-based tourism in a marine protected area

Science.gov (United States)

Marcella, Timothy K.; Gende, Scott M.; Roby, Daniel D.; Allignol, Arthur

2017-01-01

Managers of marine protected areas (MPAs) must often seek ways to allow for visitation while minimizing impacts to the resources they are intended to protect. Using shipboard observers, we quantified the “zone of disturbance” for Kittlitz’s and marbled murrelets (Brachyramphus brevirostris and B. marmoratus) exposed to large cruise ships traveling through Glacier Bay National Park, one of the largest MPAs in North America. In the upper reaches of Glacier Bay, where Kittlitz’s murrelets predominated, binary logistic regression models predicted that 61% of all murrelets within 850 m perpendicular distance of a cruise ship were disturbed (defined as flushing or diving), whereas in the lower reaches, where marbled murrelets predominated, this percentage increased to 72%. Using survival analysis, murrelets in both reaches were found to react at greater distances when ships approached indirectly, presumably because of the ship’s larger profile, suggesting murrelets responded to visual rather than audio cues. No management-relevant covariates (e.g., ship velocity, route distance from shore) were found to be important predictors of disturbance, as distance from ship to murrelet accounted for > 90% of the explained variation in murrelet response. Utilizing previously published murrelet density estimates from Glacier Bay, and applying an average empirical disturbance probability (68%) out to 850 m from a cruise ship’s typical route, we estimated that a minimum of 9.8–19.6% of all murrelets in Glacier Bay are disturbed per ship entry. Whether these disturbance levels are inconsistent with Park management objectives, which include conserving wildlife as well as providing opportunities for visitation, depends in large part on whether disturbance events caused by cruise ships have impacts on murrelet fitness, which remains uncertain.

Topic Map for Authentic Travel

OpenAIRE

Wandsvik, Atle; Zare, Mehdi

2007-01-01

E-business is a new trend in Internet use. Authentic travel is an approach to travel and travel business which helps the traveler experience what is authentic in the travel destination. But how can the traveler find those small authentic spots and organize them together to compose a vacation? E-business techniques, combined withTopic Maps, can help.

Long distance travel ‘today’

DEFF Research Database (Denmark)

Christensen, Linda

2014-01-01

This paper presents an overview of the Dane’s long distance travel. It is a part of the Drivers and Limits project about long distance travel. Long distance travel is in the project defined as infrequent travel with overnight stay. Danes 15-85 years-old travel in average 5.5 long distance travel...... per year og which a third is for international destinations, a third is for domestic second homes and a third are other domestic trips. However, 87% of the kilometres are for international destinations and only 4% are for domestic second homes. Travel activity is very uneven distributed with only half...... of the population having had a journey during the last three month. At the other hand 60% have travelled internationally during the last year and only 2% have never travelled abroad. The paper presents among other things how the travel activity is distributed on travel purpose and mode and how the mode choice...

Pre-Travel Health Preparation of Pediatric International Travelers: Analysis From the Global TravEpiNet Consortium.

Science.gov (United States)

Hagmann, Stefan; LaRocque, Regina C; Rao, Sowmya R; Jentes, Emily S; Sotir, Mark J; Brunette, Gary; Ryan, Edward T

2013-12-01

Children frequently travel internationally. Health-related data on such children are limited. We sought to investigate the demographics, health characteristics, and preventive interventions of outbound US international pediatric travelers. We analyzed data from 32 099 travelers presenting for pre-travel healthcare at the Global TravEpiNet (GTEN), a national consortium of 19 travel clinics, from January 1, 2009 to June 6, 2012. A total of 3332 (10%) of all GTEN travelers were children (traveled mostly for leisure (36%) or to visit friends or relatives (VFR) (36%). Most popular destination regions were Africa (41%), Southeast Asia (16%), Central America (16%), and the Caribbean (16%). Compared with children traveling for leisure, VFR children were more likely to present travel consultation (44% vs 28%), intended to travel for 28 days or longer (70% vs 22%), and to travel to Africa (62% vs 32%). Nearly half of the pediatric travelers (46%) received at least 1 routine vaccine, and most (83%) received at least 1 travel-related vaccine. Parents or guardians of one third of the children (30%) refused at least 1 recommended travel-related vaccine. Most pediatric travelers visiting a malaria-endemic country (72%) received a prescription for malaria chemoprophylaxis. Ten percent of travelers seeking pre-travel healthcare at GTEN sites are children. VFR-travel, pre-travel consultation close to time of departure, and refusal of recommended vaccines may place children at risk for travel-associated illness. Strategies to engage pediatric travelers in timely, pre-travel care and improve acceptance of pre-travel healthcare interventions are needed. © The Author 2013. Published by Oxford University Press on behalf of the Pediatric Infectious Diseases Society. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Loss of 'blue carbon' from coastal salt marshes following habitat disturbance.

Directory of Open Access Journals (Sweden)

Peter I Macreadie

Full Text Available Increased recognition of the global importance of salt marshes as 'blue carbon' (C sinks has led to concern that salt marshes could release large amounts of stored C into the atmosphere (as CO2 if they continue undergoing disturbance, thereby accelerating climate change. Empirical evidence of C release following salt marsh habitat loss due to disturbance is rare, yet such information is essential for inclusion of salt marshes in greenhouse gas emission reduction and offset schemes. Here we investigated the stability of salt marsh (Spartinaalterniflora sediment C levels following seagrass (Thallasiatestudinum wrack accumulation; a form of disturbance common throughout the world that removes large areas of plant biomass in salt marshes. At our study site (St Joseph Bay, Florida, USA, we recorded 296 patches (7.5 ± 2.3 m(2 mean area ± SE of vegetation loss (aged 3-12 months in a salt marsh meadow the size of a soccer field (7 275 m(2. Within these disturbed patches, levels of organic C in the subsurface zone (1-5 cm depth were ~30% lower than the surrounding undisturbed meadow. Subsequent analyses showed that the decline in subsurface C levels in disturbed patches was due to loss of below-ground plant (salt marsh biomass, which otherwise forms the main component of the long-term 'refractory' C stock. We conclude that disturbance to salt marsh habitat due to wrack accumulation can cause significant release of below-ground C; which could shift salt marshes from C sinks to C sources, depending on the intensity and scale of disturbance. This mechanism of C release is likely to increase in the future due to sea level rise; which could increase wrack production due to increasing storminess, and will facilitate delivery of wrack into salt marsh zones due to higher and more frequent inundation.

Wind Speed Prediction with Wavelet Time Series Based on Lorenz Disturbance

Directory of Open Access Journals (Sweden)

ZHANG, Y.

2017-08-01

Full Text Available Due to the sustainable and pollution-free characteristics, wind energy has been one of the fastest growing renewable energy sources. However, the intermittent and random fluctuation of wind speed presents many challenges for reliable wind power integration and normal operation of wind farm. Accurate wind speed prediction is the key to ensure the safe operation of power system and to develop wind energy resources. Therefore, this paper has presented a wavelet time series wind speed prediction model based on Lorenz disturbance. Therefore, in this paper, combined with the atmospheric dynamical system, a wavelet-time series improved wind speed prediction model based on Lorenz disturbance is proposed and the wind turbines of different climate types in Spain and China are used to simulate the disturbances of Lorenz equations with different initial values. The prediction results show that the improved model can effectively correct the preliminary prediction of wind speed, improving the prediction. In a word, the research work in this paper will be helpful to arrange the electric power dispatching plan and ensure the normal operation of the wind farm.

Travel Overview

Science.gov (United States)

Search the Division of Finance site DOF State of Alaska Finance Home Content Area Accounting Charge Cards Top Department of Administration logo Alaska Department of Administration Division of Finance Search You are here Administration / Finance / Travel Travel The Department of Administration administers the

Pre-travel care for immunocompromised and chronically ill travellers: A retrospective study

NARCIS (Netherlands)

van Aalst, Mariëlle; Verhoeven, Roos; Omar, Freshta; Stijnis, Cornelis; van Vugt, Michèle; de Bree, Godelieve J.; Goorhuis, Abraham; Grobusch, Martin P.

2017-01-01

Background: Immunocompromised and chronically ill travellers (ICCITs) are susceptible to travel related diseases. In ICCITs, pre-travel care regarding vaccinations and prophylactics is complex. We evaluated the protection level by preventive measures in ICCITs by analysing rates of vaccination

Travel-associated disease among US residents visiting US GeoSentinel clinics after return from international travel.

Science.gov (United States)

Hagmann, Stefan H F; Han, Pauline V; Stauffer, William M; Miller, Andy O; Connor, Bradley A; Hale, DeVon C; Coyle, Christina M; Cahill, John D; Marano, Cinzia; Esposito, Douglas H; Kozarsky, Phyllis E

2014-12-01

US residents make 60 million international trips annually. Family practice providers need to be aware of travel-associated diseases affecting this growing mobile population. To describe demographics, travel characteristics and clinical diagnoses of US residents who present ill after international travel. Descriptive analysis of travel-associated morbidity and mortality among US travellers seeking care at 1 of the 22 US practices and clinics participating in the GeoSentinel Global Surveillance Network from January 2000 to December 2012. Of the 9624 ill US travellers included in the analysis, 3656 (38%) were tourist travellers, 2379 (25%) missionary/volunteer/research/aid workers (MVRA), 1580 (16%) travellers visiting friends and relatives (VFRs), 1394 (15%) business travellers and 593 (6%) student travellers. Median (interquartile range) travel duration was 20 days (10-60 days). Pre-travel advice was sought by 45%. Hospitalization was required by 7%. Compared with other groups of travellers, ill MVRA travellers returned from longer trips (median duration 61 days), while VFR travellers disproportionately required higher rates of inpatient care (24%) and less frequently had received pre-travel medical advice (20%). Illnesses of the gastrointestinal tract were the most common (58%), followed by systemic febrile illnesses (18%) and dermatologic disorders (17%). Three deaths were reported. Diagnoses varied according to the purpose of travel and region of exposure. Returning ill US international travellers present with a broad spectrum of travel-associated diseases. Destination and reason for travel may help primary health care providers to generate an accurate differential diagnosis for the most common disorders and for those that may be life-threatening. © The Author 2014. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The New England travel market: generational travel patterns, 1979 to 1996

Science.gov (United States)

Rod Warnick

2002-01-01

Generations of travelers who select New England as a primary destination are examined over time from the years of 1979 through 1996 and the analysis serves to update an earlier review of generational travel patterns of the region (Warnick, 1994). Changes in travel patterns are noted by overall adjusted annual change rates by demographic and geographic regions of...

Travel Daily China Travel Innovation Summit to Be Held in Beijing

Institute of Scientific and Technical Information of China (English)

2009-01-01

Guangzhou,China,April 7th- TravelDaily (www.traveldaily.cn), China’s leading online publisher and event organizer with emphasis on trends in the distribution,marketing and technology of the travel and tourism industries,today announced it will partner with PhoCusWright to host the 2009 China Travel Innovation Summit in Beijing from May 12 to 13,2009.

Travel Behavior Change in Older Travelers: Understanding Critical Reactions to Incidents Encountered in Public Transport.

Science.gov (United States)

Sundling, Catherine

2015-11-18

Accessibility of travel may be better understood if psychological factors underlying change in travel behavior are known. This paper examines older (65+) travelers' motives for changing their travel behavior. These changes are grounded in critical incidents earlier encountered in public-transport travel. A scientific framework is developed based on cognitive and behavioral theory. In 29 individual interviews, travelers' critical reactions (i.e., cognitive, emotional, and/or behavioral) to 77 critical incidents were examined. By applying critical incident technique (CIT), five reaction themes were identified that had generated travel-behavior change: firm restrictions, unpredictability, unfair treatment, complicated trips, and earlier adverse experiences. To improve older travelers' access to public transport, key findings were: (a) service must be designed so as to strengthen the feeling of being in control throughout the journey; (b) extended personal service would increase predictability in the travel chain and decrease travel complexity; consequently, (c) when designing new services and making effective accessibility interventions, policy makers should consider and utilize underlying psychological factors that could direct traveler behavior.

A statistical-based approach for acoustic tomography of the atmosphere.

Science.gov (United States)

Kolouri, Soheil; Azimi-Sadjadi, Mahmood R; Ziemann, Astrid

2014-01-01

Acoustic travel-time tomography of the atmosphere is a nonlinear inverse problem which attempts to reconstruct temperature and wind velocity fields in the atmospheric surface layer using the dependence of sound speed on temperature and wind velocity fields along the propagation path. This paper presents a statistical-based acoustic travel-time tomography algorithm based on dual state-parameter unscented Kalman filter (UKF) which is capable of reconstructing and tracking, in time, temperature, and wind velocity fields (state variables) as well as the dynamic model parameters within a specified investigation area. An adaptive 3-D spatial-temporal autoregressive model is used to capture the state evolution in the UKF. The observations used in the dual state-parameter UKF process consist of the acoustic time of arrivals measured for every pair of transmitter/receiver nodes deployed in the investigation area. The proposed method is then applied to the data set collected at the Meteorological Observatory Lindenberg, Germany, as part of the STINHO experiment, and the reconstruction results are presented.

Active disturbance rejection control based robust output feedback autopilot design for airbreathing hypersonic vehicles.

Science.gov (United States)

Tian, Jiayi; Zhang, Shifeng; Zhang, Yinhui; Li, Tong

2018-03-01

Since motion control plant (y (n) =f(⋅)+d) was repeatedly used to exemplify how active disturbance rejection control (ADRC) works when it was proposed, the integral chain system subject to matched disturbances is always regarded as a canonical form and even misconstrued as the only form that ADRC is applicable to. In this paper, a systematic approach is first presented to apply ADRC to a generic nonlinear uncertain system with mismatched disturbances and a robust output feedback autopilot for an airbreathing hypersonic vehicle (AHV) is devised based on that. The key idea is to employ the feedback linearization (FL) and equivalent input disturbance (EID) technique to decouple nonlinear uncertain system into several subsystems in canonical form, thus it would be much easy to directly design classical/improved linear/nonlinear ADRC controller for each subsystem. It is noticed that all disturbances are taken into account when implementing FL rather than just omitting that in previous research, which greatly enhances controllers' robustness against external disturbances. For autopilot design, ADRC strategy enables precise tracking for velocity and altitude reference command in the presence of severe parametric perturbations and atmospheric disturbances only using measurable output information. Bounded-input-bounded-output (BIBO) stable is analyzed for closed-loop system. To illustrate the feasibility and superiority of this novel design, a series of comparative simulations with some prominent and representative methods are carried out on a benchmark longitudinal AHV model. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

THE DECISION MAKING OF BUSINESS TRAVELLERS IN SELECTING ONLINE TRAVEL PORTALS FOR TRAVEL BOOKING: AN EMPIRICAL STUDY OF DELHI NATIONAL CAPITAL REGION, INDIA

OpenAIRE

Bivek DATTA; Manohar SAJNANI; Joby THOMAS

2018-01-01

The purpose of this paper is to understand the decision making pattern of the Business Travellers in Delhi National Capital Region in India while booking their trips through Online Travel Portals. The study revolves around purchase decision pattern of Business Travellers by investigating their travel decision making style in selecting online travel portals for their trip booking. The authors have adopted the quantitative methodology to achieve the objective of the study. The study is confi...

Travel Behavior Change in Older Travelers: Understanding Critical Reactions to Incidents Encountered in Public Transport

OpenAIRE

Sundling, Catherine

2015-01-01

Accessibility of travel may be better understood if psychological factors underlying change in travel behavior are known. This paper examines older (65+) travelers? motives for changing their travel behavior. These changes are grounded in critical incidents earlier encountered in public-transport travel. A scientific framework is developed based on cognitive and behavioral theory. In 29 individual interviews, travelers? critical reactions (i.e., cognitive, emotional, and/or behavioral) to 77 ...

You, too, can be an international medical traveler: Reading medical travel guidebooks

NARCIS (Netherlands)

Ormond, M.E.; Sothern, M.

2012-01-01

Drawing on literature on self-help and travel guide writing, this paper interrogates five international medical travel guidebooks aimed at encouraging American and British audiences to travel abroad to purchase medical care. These guidebooks articulate a three-step self-help “program” to produce a

Toward an Improved Representation of Middle Atmospheric Dynamics Thanks to the ARISE Project

Science.gov (United States)

Blanc, E.; Ceranna, L.; Hauchecorne, A.; Charlton-Perez, A.; Marchetti, E.; Evers, L. G.; Kvaerna, T.; Lastovicka, J.; Eliasson, L.; Crosby, N. B.; Blanc-Benon, P.; Le Pichon, A.; Brachet, N.; Pilger, C.; Keckhut, P.; Assink, J. D.; Smets, P. S. M.; Lee, C. F.; Kero, J.; Sindelarova, T.; Kämpfer, N.; Rüfenacht, R.; Farges, T.; Millet, C.; Näsholm, S. P.; Gibbons, S. J.; Espy, P. J.; Hibbins, R. E.; Heinrich, P.; Ripepe, M.; Khaykin, S.; Mze, N.; Chum, J.

2018-03-01

This paper reviews recent progress toward understanding the dynamics of the middle atmosphere in the framework of the Atmospheric Dynamics Research InfraStructure in Europe (ARISE) initiative. The middle atmosphere, integrating the stratosphere and mesosphere, is a crucial region which influences tropospheric weather and climate. Enhancing the understanding of middle atmosphere dynamics requires improved measurement of the propagation and breaking of planetary and gravity waves originating in the lowest levels of the atmosphere. Inter-comparison studies have shown large discrepancies between observations and models, especially during unresolved disturbances such as sudden stratospheric warmings for which model accuracy is poorer due to a lack of observational constraints. Correctly predicting the variability of the middle atmosphere can lead to improvements in tropospheric weather forecasts on timescales of weeks to season. The ARISE project integrates different station networks providing observations from ground to the lower thermosphere, including the infrasound system developed for the Comprehensive Nuclear-Test-Ban Treaty verification, the Lidar Network for the Detection of Atmospheric Composition Change, complementary meteor radars, wind radiometers, ionospheric sounders and satellites. This paper presents several examples which show how multi-instrument observations can provide a better description of the vertical dynamics structure of the middle atmosphere, especially during large disturbances such as gravity waves activity and stratospheric warming events. The paper then demonstrates the interest of ARISE data in data assimilation for weather forecasting and re-analyzes the determination of dynamics evolution with climate change and the monitoring of atmospheric extreme events which have an atmospheric signature, such as thunderstorms or volcanic eruptions.

Valuing travel time variability: Characteristics of the travel time distribution on an urban road

DEFF Research Database (Denmark)

Fosgerau, Mogens; Fukuda, Daisuke

2012-01-01

This paper provides a detailed empirical investigation of the distribution of travel times on an urban road for valuation of travel time variability. Our investigation is premised on the use of a theoretical model with a number of desirable properties. The definition of the value of travel time...... variability depends on certain properties of the distribution of random travel times that require empirical verification. Applying a range of nonparametric statistical techniques to data giving minute-by-minute travel times for a congested urban road over a period of five months, we show that the standardized...... travel time is roughly independent of the time of day as required by the theory. Except for the extreme right tail, a stable distribution seems to fit the data well. The travel time distributions on consecutive links seem to share a common stability parameter such that the travel time distribution...

DE 2 observations of disturbances in the upper atmosphere during a geomagnetic storm

International Nuclear Information System (INIS)

Miller, N.J.; Brace, L.H.; Spencer, N.W.; Carignan, G.R.

1990-01-01

Data taken in the dusk sector of the mid-latitude thermosphere at 275-450 km by instruments on board Dynamics Explorer 2 in polar orbit are used to examine the response of the ionosphere- thermosphere system during a geomagnetic storm. The results represent the first comparison of nearly simultaneous measurements of storm disturbances in dc electric fields, zonal ion convection, zonal winds, gas composition and temperature, and electron density and temperature, at different seasons in a common local time sector. The storm commenced on November 24, 1982, during the interaction of a solar wind disturbance with the geomagnetic field while the north-south component of the interplanetary magnetic field, B z , was northward. The storm main phase began while B z was turning southward. Storm-induced variations in meridional de electric fields, neutral composition, and N e were stronger and spread farther equatorward in the winter hemisphere. Westward ion convection was intense enough to produce westward winds of 600 m s - 1 via ion drag in the winter hemisphere. Frictional heating was sufficient to elevate ion temperatures above electron temperatures in both seasons and to produce large chemical losses of O + by increasing the rate of O + loss via ion-atom interchange. Part of the chemical loss of O + was compensated by upward flow of O + as the ion scale height adjusted to the increasing ion temperatures. In this storm, frictional heating was an important subauroral heat source equatorward to at least 53 degree invariant latitude

Travel intermediaries and responsibility for compliance with EU travel law : A scattered legal picture

NARCIS (Netherlands)

de Vries, Anne

Travel intermediaries, commonly known as travel agencies, are important and well-known actors in the travel sector and online travel agencies such as Expedia, Booking.com and AirBnB are booming. Although intermediaries obviously bring clear benefits for contracting parties, they also complicate the

Representation of Central Asia and Traveling Self in Vambery’s Travels in Central Asia

Directory of Open Access Journals (Sweden)

Ahmad Gholi

2016-03-01

Full Text Available In the course of the nineteenth century Arminius Vambery, an anglophile travel writer, in the guise of a mendicant dervish with a group of Tartar pilgrims departs to secluded and sealed Central Asia. After six months travel in the Khanates of Central Asia, he undertakes a journey to England where he offers his observations to the Royal Geographical Society and publishes his travelogue, Travel in Central Asia. Despite its literary merits and connection with British imperialism, the travelogue has not been scrutinized separately by the scholars of travel writing. To fill the gap, this article by drawing on the theories of post-structuralism: Orientalism and Postcolonialism, endeavors to unveil the political agenda behind the travel writer’s representation of his travelees, destination, and his own traveling self. Additionally, it argues that the travel writer in dialogue with other Western travel writers to deterritorialize his traversed region or justify the prospective presence of Britain in Central Asia, represents his journey destination as the locus of barbarity, a region under the grip of despotic rulers, as well as an area with frozen time, while to exhibit his Eurocentrism, he portrays his traveling subject as the a suffering hero and a benign traveler.

Travelers' Health: HIV Infection

Science.gov (United States)

... Last-Minute Travel Long-Term Travel Mass Gatherings Medical Tourism Mental Health Motion Sickness Natural Disasters Pregnant Travelers ... for purposes of medical treatment (see Chapter 2, Medical Tourism ), the blood and blood products used in the ...

Intercity Travel Demand Analysis Model

OpenAIRE

Ming Lu; Hai Zhu; Xia Luo; Lei Lei

2014-01-01

It is well known that intercity travel is an important component of travel demand which belongs to short distance corridor travel. The conventional four-step method is no longer suitable for short distance corridor travel demand analysis for the time spent on urban traffic has a great impact on traveler's main mode choice. To solve this problem, the author studied the existing intercity travel demand analysis model, then improved it based on the study, and finally established a combined model...

Travel opinion leaders and seekers

DEFF Research Database (Denmark)

Yoo, Kyung-Hyan; Gretzel, Ulrike; Zach, Florian

2011-01-01

While opinion leadership has been recognized as important in tourism, there has been very little empirical research investigating the phenomenon. Given new developments in social media technologies, it is especially important to understand whether travel opinion leadership and seeking are drivers...... of specific social media perceptions and behaviours. Based on an online survey of US online travellers, this paper seeks to identify travel opinion leaders and seekers and their characteristics. Further, the research conducted investigated linkages between travel opinion leadership/seeking and travel social...... media use. The findings suggest that travel opinion leadership and seeking are distinct but connected. Both opinion leaders and seekers are technology savvy, young, educated, involved in travel planning and engaged in social media use for travel. What distinguishes opinion leaders is their greater...

Motivations, image dimensions and affective qualities of places: the choice of place and photos in tourism and leisure travels

Directory of Open Access Journals (Sweden)

Flavia Luciane Scherer

2015-12-01

Full Text Available Tourism is dependent on aspects that motivate people to travel and what they expect to receive. This study aimed to explore the dimensions of the images and affective qualities of places in tourism and leisure travel photos. Aimed also to identify the motivations that influence the choice of tourist destination. We conducted two studies. The first was a survey wtih 232 people who made tourism or leisure travel in the last three years. The second stage of the research, was performed by application of 12 interviews with leisure or tourism travel consumers. The results show that the affective image, the atmosphere and leisure are the most determinant dimensions in the choice of destination. It was also found that feelings of respondents in relation to your photo turn to the affective and emotional field.

Travel experience ecosystem model : building travel agencies’ business resilience in Portugal

OpenAIRE

Salvado, Josefina

2011-01-01

The Portuguese tourism distribution recognizes in the digital economy drivers - based on e-business, collaborative networks and information exchange - an incentive to productivity and rendibility, leading to sustainable competitive advantages. Travel agencies live currently in a Darwinian business-oriented environment, where only resilient entrepreneurs are able to survive. This framing allows the genesis of a new theoretical archetype of travel agencies, the “TEEM - Travel Exp...

The Connected Traveler

Energy Technology Data Exchange (ETDEWEB)

Young, Stanley

2017-04-24

The Connected Traveler project is a multi-disciplinary undertaking that seeks to validate potential for transformative transportation system energy savings by incentivizing energy efficient travel behavior.

Determination of traces of fluorine and hydrofluoric acid in the atmosphere

International Nuclear Information System (INIS)

Francois, H.; Grand-Clement, A.M.; Faltot, G.

1963-01-01

As some publications highlighted hazards related to the presence of dispersed fluorine and hydrofluoric acid in the atmosphere, the authors, after a brief recall of some measurement devices presented in some publications, present an experimental set-up which aims at measuring traces of these compounds in the atmosphere. They notably describe the preparation of a controlled fluorine atmosphere, discuss the efficiency of the absorption-based trap, report the study of the electrolytic analysis cell, discuss its calibration. They also report the study of the influence of temperature and of the presence of disturbing ions

Traveling-wave photodetector

Science.gov (United States)

Hietala, V.M.; Vawter, G.A.

1993-12-14

The traveling-wave photodetector of the present invention combines an absorptive optical waveguide and an electrical transmission line, in which optical absorption in the waveguide results in a photocurrent at the electrodes of the electrical transmission line. The optical waveguide and electrical transmission line of the electrically distributed traveling-wave photodetector are designed to achieve matched velocities between the light in the optical waveguide and electrical signal generated on the transmission line. This velocity synchronization provides the traveling-wave photodetector with a large electrical bandwidth and a high quantum efficiency, because of the effective extended volume for optical absorption. The traveling-wave photodetector also provides large power dissipation, because of its large physical size. 4 figures.

A cross-sectional study of pre-travel health-seeking practices among travelers departing Sydney and Bangkok airports.

Science.gov (United States)

Heywood, Anita E; Watkins, Rochelle E; Iamsirithaworn, Sopon; Nilvarangkul, Kessarawan; MacIntyre, C Raina

2012-05-02

Pre-travel health assessments aim to promote risk reduction through preventive measures and safe behavior, including ensuring travelers are up-to-date with their immunizations. However, studies assessing pre-travel health-seeking practices from a variety of medical and non-medical sources and vaccine uptake prior to travel to both developing and developed countries within the Asia-Pacific region are scarce. Cross-sectional surveys were conducted between July and December 2007 to assess pre-travel health seeking practices, including advice from health professionals, health information from other sources and vaccine uptake, in a sample of travelers departing Sydney and Bangkok airports. A two-stage cluster sampling technique was used to ensure representativeness of travelers and travel destinations. Pre-travel health seeking practices were assessed using a self-administered questionnaire distributed at the check-in queues of departing flights. Logistic regression models were used to identify significant factors associated with seeking pre-travel health advice from a health professional, reported separately for Australian residents, residents of other Western countries and residents of countries in Asia. A total of 843 surveys were included in the final sample (Sydney 729, response rate 56%; Bangkok 114, response rate 60%). Overall, pre-travel health information from any source was sought by 415 (49%) respondents with 298 (35%) seeking pre-travel advice from a health professional, the majority through general practice. Receipt of a pre-travel vaccine was reported by 100 (12%) respondents. Significant factors associated with seeking pre-travel health advice from a health professional differed by region of residence. Asian travelers were less likely to report seeking pre-travel health advice and uptake of pre-travel vaccines than Australian or other Western travelers. Migrant Australians were less likely to report seeking pre-travel health advice than Australian

A cross-sectional study of pre-travel health-seeking practices among travelers departing Sydney and Bangkok airports

Science.gov (United States)

2012-01-01

Background Pre-travel health assessments aim to promote risk reduction through preventive measures and safe behavior, including ensuring travelers are up-to-date with their immunizations. However, studies assessing pre-travel health-seeking practices from a variety of medical and non-medical sources and vaccine uptake prior to travel to both developing and developed countries within the Asia-Pacific region are scarce. Methods Cross-sectional surveys were conducted between July and December 2007 to assess pre-travel health seeking practices, including advice from health professionals, health information from other sources and vaccine uptake, in a sample of travelers departing Sydney and Bangkok airports. A two-stage cluster sampling technique was used to ensure representativeness of travelers and travel destinations. Pre-travel health seeking practices were assessed using a self-administered questionnaire distributed at the check-in queues of departing flights. Logistic regression models were used to identify significant factors associated with seeking pre-travel health advice from a health professional, reported separately for Australian residents, residents of other Western countries and residents of countries in Asia. Results A total of 843 surveys were included in the final sample (Sydney 729, response rate 56%; Bangkok 114, response rate 60%). Overall, pre-travel health information from any source was sought by 415 (49%) respondents with 298 (35%) seeking pre-travel advice from a health professional, the majority through general practice. Receipt of a pre-travel vaccine was reported by 100 (12%) respondents. Significant factors associated with seeking pre-travel health advice from a health professional differed by region of residence. Asian travelers were less likely to report seeking pre-travel health advice and uptake of pre-travel vaccines than Australian or other Western travelers. Migrant Australians were less likely to report seeking pre-travel health

Traveling wave laser system

International Nuclear Information System (INIS)

Gregg, D.W.; Kidder, R.E.; Biehl, A.T.

1975-01-01

The invention broadly involves a method and means for generating a traveling wave laser pulse and is basically analogous to a single pass light amplifier system. However, the invention provides a traveling wave laser pulse of almost unlimited energy content, wherein a gain medium is pumped in a traveling wave mode, the traveling wave moving at essentially the velocity of light to generate an amplifying region or zone which moves through the medium at the velocity of light in the presence of directed stimulating radiation, thereby generating a traveling coherent, directed radiation pulse moving with the amplification zone through the gain medium. (U.S.)

Effects in atmospheric electricity daily variation controlled by solar wind

International Nuclear Information System (INIS)

Ptitsyna, N.G.; Tyasto, M.I.; Levitin, A.E.; Gromova, L.A.; Tuomi, T.; AN SSSR, Moscow

1995-01-01

An analysis of fair weather atmospheric electricity, one of the environmental factors which affects the biosphere, is conducted. A distinct difference in the diurnal variation of atmospheric electric field at Helsinki is found between disturbed and extremely quiet conditions in the magnetosphere in winter before midnight. The comparison with the numerical model of the ionospheric electric field based on the solar wind parameters reveals that the maximum contribution of the magnetospheric-ionospheric generator to atmospheric electric field is about 100-150 v/m which assumes values of about 30% of the surface field. 8 refs.; 2 figs

Toward an Improved Representation of Middle Atmospheric Dynamics Thanks to the ARISE Project

Czech Academy of Sciences Publication Activity Database

Blanc, E.; Ceranna, L.; Hauchecorne, A.; Charlton-Perez, A.; Marchetti, E.; Evers, L.G.; Kvaerna, T.; Laštovička, Jan; Eliasson, L.; Crosby, N. B.; Blanc-Benon, P.; Le Pichon, A.; Brachet, N.; Pilger, C.; Keckhut, P.; Assink, J.D.; Smets, P. S. M.; Lee, C. F.; Kero, J.; Šindelářová, Tereza; Kämpfer, N.; Rüfenacht, R.; Farges, T.; Millet, C.; Näsholm, S. P.; Gibbons, S. J.; Espy, P. J.; Hibbins, R. E.; Heinrich, P.; Ripepe, M.; Khaykin, S.; Mze, N.; Chum, Jaroslav

2018-01-01

Roč. 39, č. 2 (2018), s. 171-225 ISSN 0169-3298 EU Projects: European Commission(XE) 284387 - ARISE; European Commission(XE) 653980 - ARISE2 Institutional support: RVO:68378289 Keywords : Atmospheric dynamics * Middle atmosphere * Infrasound * Gravity waves * Volcanoes * Atmospheric disturbances * Extreme events * stratospheric temperature trends * total solar eclipse * wave momentum flux * natural infrasound * acoustic-waves * polar-low * model simulations * sudden warmings * Doppler lidar Subject RIV: DG - Athmosphere Sciences, Meteorology OBOR OECD: Meteorology and atmospheric sciences Impact factor: 4.413, year: 2016 https://link.springer.com/article/10.1007/s10712-017-9444-0

Mind your travel ! Motivation, time use, and intent : Three factors of travel to be investigated

OpenAIRE

PAPON , Francis; Meissonnier , Joël

2013-01-01

The objective is to investigate the drivers of travel demand beyond the need to travel to destination; travellers may engage a trip for the sake of it, at least to some extent: travel includes a share of 'primary utility'. The paper focuses on two types of data and analysis: the primary utility of travel questions passed in the last French national travel survey, and eight dimensions of a trip proposed from a sociological analysis. The paper mixes these approaches and correlate survey answ...

A travel clinic in your office: grow your practice and protect international travelers.

Science.gov (United States)

Kirsch, Michael

2009-01-01

Medical practices today face economic challenges from declining reimbursements and rising overhead costs. Physicians need to develop new income sources to invigorate their practices and remain viable. Travel medicine-advising and immunizing international travelers-is a rapidly growing specialty in the United States that generates substantial cash reimbursements and professional satisfaction. Travel Clinics of America, a physician-operated company, specializes in helping physicians to incorporate travel medicine into their existing practices.

Health hazards of international travel.

Science.gov (United States)

Cossar, J H; Reid, D

1989-01-01

The growth of travel and the increasing numbers of those affected by travel-related illnesses, some of a serious nature, will cause this subject to demand the attention of the medical profession, the travel trade, travellers themselves and the health authorities of countries receiving tourists. Provision of appropriate advice for the traveller is a shared responsibility, best channelled mainly through travel agencies; it can moreover be shown to be cost-beneficial. Continued monitoring of illness in travellers and provision of information systems geared to this problem and its prevention are fully justified. They should be based on traditional channels of communication and currently-available modern technology, and be readily accessible to medical and related workers. Increased collaboration between medical workers, health educators and those involved in the travel trade would be a positive and useful contribution towards the reduction of illness and discomfort among travellers and the associated expense incurred by the various national health services concerned. There are clearly economic benefits from the development of international tourism, but these have to be balanced in countries accepting tourists by attention to the prevention of illnesses associated with travel.

Travel medicine and mHealth technology: a study using smartphones to collect health data during travel.

Science.gov (United States)

Farnham, Andrea; Blanke, Ulf; Stone, Emily; Puhan, Milo A; Hatz, Christoph

2016-06-01

mHealth methodology such as smartphone applications offers new opportunities to capture the full range of health risks during travel in real time. Our study aims to widen the scope of travel health research in tropical and subtropical destinations by using a smartphone application to collect detailed information on health behaviours, clinical symptoms, accidents and environmental factors during travel. We enrolled travel clinic clients in Zurich and Basel ≥18 years of age travelling to Thailand for travel. Participants were equipped with a smartphone and an application that (1) actively administers a daily self-report questionnaire on the health risks, behaviours and symptoms the traveller encountered, and (2) passively collects information on the traveller's location and environmental conditions by transformation of raw GPS data. A prospective cohort of 101 travellers planning travel to Thailand between January and June 2015 was recruited. Of the 101 enrolled travellers, 75 (74.3%) answered at least one questionnaire during travel, 10 (9.9%) had technical difficulties and 16 (15.8%) dropped out. Those who completed questionnaires were a median of 27.0 years old (range 18-57). Travellers filled out a median of 12.0 questionnaires during their trip (range 1-30), corresponding to a median completion rate of 85.0% days of travel. The typical example of a healthy female traveller shows that many and diverse health issues arise during a trip that clusters on certain days. The rich data on behaviour and local environment may be used to explain the occurrence and clustering of health issues. Use of a smartphone app to collect health information is technically feasible and acceptable amongst a traveller population, minimizes recall bias and greatly increases the quality and quantity of data collected during travel. mHealth technology shows great potential for innovation in travel medicine. © International Society of Travel Medicine, 2016. All rights reserved

Knowledge Representation in Travelling Texts

DEFF Research Database (Denmark)

Mousten, Birthe; Locmele, Gunta

2014-01-01

Today, information travels fast. Texts travel, too. In a corporate context, the question is how to manage which knowledge elements should travel to a new language area or market and in which form? The decision to let knowledge elements travel or not travel highly depends on the limitation...... and the purpose of the text in a new context as well as on predefined parameters for text travel. For texts used in marketing and in technology, the question is whether culture-bound knowledge representation should be domesticated or kept as foreign elements, or should be mirrored or moulded—or should not travel...... at all! When should semantic and pragmatic elements in a text be replaced and by which other elements? The empirical basis of our work is marketing and technical texts in English, which travel into the Latvian and Danish markets, respectively....

76 FR 43236 - Federal Travel Regulation (FTR): Temporary Duty (TDY) Travel Allowances: Notice of Public Meeting

Science.gov (United States)

2011-07-20

...; Sequence 5] Federal Travel Regulation (FTR): Temporary Duty (TDY) Travel Allowances: Notice of Public... public meeting. SUMMARY: The General Services Administration (GSA) is revising the Federal Travel Regulation (FTR) in an effort to streamline travel policies, increase travel efficiency and effectiveness...

Travel, infection and immunity

OpenAIRE

Soonawala, Darius

2016-01-01

Preface: The content of this thesis is based on research that was conducted at the travel and vaccination clinic at Leiden University Medical Centre (LUMC). This clinic provides pre-travel care to the general population, and to special groups of travellers, such as patients who use immunosuppressants or who have chronic diseases. The clinic is closely connected to the department of Infectious Diseases at LUMC. The setting of a travel clinic within an academic medical hospital, provides unique...

Exploring disagreement prevention and resolution in travel decision-making of young Chinese travellers

OpenAIRE

Song, Hanqun; Sparks, Beverley; Wang, Ying

2017-01-01

The young Chinese travel market is becoming increasingly significant in domestic and international tourism. However, there is limited research on the market. This study examines the decision-making processes of young Chinese travellers, with a particular interest in disagreement prevention and resolution. On the basis of interviews with 25 young Chinese travellers, this study found that while a small number of travellers did not perceive any disagreement, or did not voice their disagreement, ...

Travel advice for the immunocompromised traveler: prophylaxis, vaccination, and other preventive measures

Directory of Open Access Journals (Sweden)

Patel RR

2015-02-01

Full Text Available Rupa R Patel,1 Stephen Y Liang,1 Pooja Koolwal,2 Frederick Matthew Kuhlmann1 1Division of Infectious Diseases, 2Division of Medical Education, Washington University School of Medicine, St Louis, MO, USA Abstract: Immunocompromised patients are traveling at increasing rates. Physicians caring for these complex patients must be knowledgeable in pretravel consultation and recognize when referral to an infectious disease specialist is warranted. This article outlines disease prevention associated with international travel for adults with human immunodeficiency virus, asplenia, solid organ and hematopoietic transplantation, and other immunosuppressed states. While rates of infection may not differ significantly between healthy and immunocompromised travelers, the latter are at greater risk for severe disease. A thorough assessment of these risks can ensure safe and healthy travel. The travel practitioners’ goal should be to provide comprehensive risk information and recommend appropriate vaccinations or prevention measures tailored to each patient’s condition. In some instances, live vaccines and prophylactic medications may be contraindicated. Keywords: immunocompromised, vaccines, travel, malaria, diarrhea

Travel Characteristics and Pretravel Health Care Among Pregnant or Breastfeeding U.S. Women Preparing for International Travel.

Science.gov (United States)

Hagmann, Stefan H F; Rao, Sowmya R; LaRocque, Regina C; Erskine, Stefanie; Jentes, Emily S; Walker, Allison T; Barnett, Elizabeth D; Chen, Lin H; Hamer, Davidson H; Ryan, Edward T

2017-12-01

To study characteristics and preventive interventions of adult pregnant and breastfeeding travelers seeking pretravel health care in the United States. This cross-sectional study analyzed data (2009-2014) of pregnant and breastfeeding travelers seen at U.S. travel clinics participating in Global TravEpiNet. Nonpregnant, nonbreastfeeding adult female travelers of childbearing age were used for comparison. We evaluated the prescription of malaria chemoprophylaxis and antibiotics for this population as well as the administration of three travel-related vaccines: hepatitis A, typhoid, and yellow fever. We also evaluated use of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis and influenza vaccines, because these are widely recommended in pregnancy. Of 21,138 female travelers of childbearing age in Global TravEpiNet, 170 (0.8%) were pregnant and 139 (0.7%) were breastfeeding. Many traveled to destinations endemic for mosquito-borne illnesses, including malaria (pregnant: 95%; breastfeeding: 94%), dengue (pregnant: 87%; breastfeeding: 81%), or yellow fever (pregnant: 35%; breastfeeding: 50%). Compared with nonpregnant, nonbreastfeeding adult female travelers, eligible pregnant travelers were less likely to be vaccinated against hepatitis A (28% compared with 51%, Ptravelers did not receive influenza vaccination. Yellow fever vaccine was occasionally provided to pregnant and breastfeeding travelers traveling to countries entirely endemic for yellow fever (6 [20%] of 30 pregnant travelers and 18 [46%] of 39 breastfeeding travelers). Half of pregnant travelers and two thirds of breastfeeding travelers preparing to travel to malaria-holoendemic countries received a prescription for malaria prophylaxis. Most pregnant and breastfeeding travelers seen for pretravel health consultations traveled to destinations with high risk for vector-borne or other travel-related diseases. Destination-specific preventive interventions were frequently underused.

The value of travel time variance

DEFF Research Database (Denmark)

Fosgerau, Mogens; Engelson, Leonid

2011-01-01

This paper considers the value of travel time variability under scheduling preferences that are defined in terms of linearly time varying utility rates associated with being at the origin and at the destination. The main result is a simple expression for the value of travel time variability...... that does not depend on the shape of the travel time distribution. The related measure of travel time variability is the variance of travel time. These conclusions apply equally to travellers who can freely choose departure time and to travellers who use a scheduled service with fixed headway. Depending...... on parameters, travellers may be risk averse or risk seeking and the value of travel time may increase or decrease in the mean travel time....

76 FR 46216 - Federal Travel Regulation (FTR): Temporary Duty (TDY) Travel Allowances: Notice of Public Meeting...

Science.gov (United States)

2011-08-02

...; Sequence 5] Federal Travel Regulation (FTR): Temporary Duty (TDY) Travel Allowances: Notice of Public... and the general public in an effort to streamline travel policies, incorporated travel efficiency and.... Flynn, Deputy Director, Office of Travel, Transportation & Asset Management. [FR Doc. 2011-19482 Filed 8...

Costs of travel time uncertainty and benefits of travel time information: Conceptual model and numerical examples

NARCIS (Netherlands)

Ettema, D.F.; Timmermans, H.J.P.

2006-01-01

A negative effect of congestion that tends to be overlooked is travel time uncertainty. Travel time uncertainty causes scheduling costs due to early or late arrival. The negative effects of travel time uncertainty can be reduced by providing travellers with travel time information, which improves

Traveling wave laser system

International Nuclear Information System (INIS)

Gregg, D.W.; Kidder, R.E.; Biehl, A.T.

1975-01-01

A method is described for generating a traveling wave laser pulse of almost unlimited energy content wherein a gain medium is pumped into a traveling wave mode, the traveling wave moving at essentially the velocity of light to generate an amplifying region or zone which moves through the medium at the velocity of light in the presence of directed stimulating radiation, thereby generating a traveling coherent, directed radiation pulse moving with the amplification zone through the gain medium. (U.S.)

Travel, infection and immunity

NARCIS (Netherlands)

Soonawala, Darius

2016-01-01

Preface: The content of this thesis is based on research that was conducted at the travel and vaccination clinic at Leiden University Medical Centre (LUMC). This clinic provides pre-travel care to the general population, and to special groups of travellers, such as patients who use

Modelling urban travel times

NARCIS (Netherlands)

Zheng, F.

2011-01-01

Urban travel times are intrinsically uncertain due to a lot of stochastic characteristics of traffic, especially at signalized intersections. A single travel time does not have much meaning and is not informative to drivers or traffic managers. The range of travel times is large such that certain

Travelers' Health: Trypanosomiasis, American (Chagas Disease)

Science.gov (United States)

... Stamaril clinics Disease Directory Resources Resources for Travelers Adventure Travel Animal Safety Blood Clots Bug Bites Evite ... Minute Travel Long-Term Travel Mass Gatherings Medical Tourism Mental Health Motion Sickness Natural Disasters Pregnant Travelers ...

TRAVEL AND HOME LEAVE

CERN Multimedia

Human Resources Division

2002-01-01

Administrative procedures for : Travel to the home station and home leave (hl) Additional travel to the home station (at) Travel to the home station and home leave for family reasons (hlf) As part of the process of simplifying administrative procedures, HR and AS Divisions have devised a new, virtually automatic procedure for payment of travel expenses to the home station. The changes are aimed at rationalising administrative procedures and not at reducing benefits. The conditions of eligibility are unchanged. The new procedure, which will be operational with effect from 1st June 2002, will greatly simplify the administrative processing of claims for travel expenses and the recording of home leaves. Currently, requests for payment are introduced manually into the Advances and Claims system (AVCL) by divisional secretariats. All travel to the home station starting prior to 1st June 2002 will be processed according to the existing system whereas that starting on 1st June and after will be processed accordi...

Residential self-selection and travel : The relationship between travel-related attitudes, built environment characteristics and travel behaviour

NARCIS (Netherlands)

Bohte, W.

2010-01-01

Most Western national governments aim to influence individual travel patterns – at least to some degree – through spatial planning in residential areas. Nevertheless, the extent to which the characteristics of the built environment influence travel behaviour remains the subject of some debate among

Writing Travel in the Anthropocene

DEFF Research Database (Denmark)

Graulund, Rune

2016-01-01

the Anthropocene - which is to say an age in which nowhere, not the furthest reachest of the stratosphere nor the lowest point in the marine abyss, are untouched by the activities and detritus of humankind. The essay will give a short overview of the manner in which the notion of 'travel' has been contested......Travel writing critics have proclaimed the end of travel since at least the beginning of the 20th Century. Yet the global age of the 21st century presents us with a range a problems that challenge the notion of travel in manners that neither travellers, travel writers, nor travel writing critics...... could have imagined just a century ago. Globalisation and increased mobility, whether it is that of the privileged few who can travel on holiday on jet airplanes, or that of the immigrant labourer seeking employment by crossing borders on foot, have meant millions (if not indeed billions) are constantly...

The global carbon cycle change: Le Chatelier principle in the response of biota to changing CO2 concentration in the atmosphere

International Nuclear Information System (INIS)

Gorshkov, V.G.; Sherman, S.G.; Kondratyev, K.Y.

1990-01-01

The long-term existence of natural biota in the environment means that such a system is stable with respect to external disturbances. This system must follow the Le Chatelier principle which is based on the processes that compensate the disturbing effects. The use of the Le Chatelier principle makes it possible to choose between contradictory observational data. Available observational data on variations of the concentration of rare carbon isotopes in various media show that the oceanic biota follows the Le Chatelier principle and absorbs about half the carbon which the ocean gets from the atmosphere, compensating an increment of carbon in the atmosphere caused by an anthropogenic impact. The strongly anthropogenetically disturbed land biota does not follow the Le Chatelier principle, starting from the middle of this century. The land biota not only cannot absorb excess carbon accumulated in the atmosphere: it ejects carbon to the atmosphere in quantities equal to halved emission of carbon through fossil fuel burning. All the quantitative results considered in this paper have been obtained without using models of the biota and of the ocean

Dynamic Mesoscale Land-Atmosphere Feedbacks in Fragmented Forests in Amazonia

Science.gov (United States)

Rastogi, D.; Baidya Roy, S.

2011-12-01

This paper investigates land-atmosphere feedbacks in disturbed rainforests of Amazonia. Deforestation along the rapidly expanding highways and road network has created the unique fishbone land cover pattern in Rondonia, a state in southwestern Amazonia. Numerical experiments and observations show that sharp gradients in land cover due to the fishbone heterogeneity triggers mesoscale circulations. These circulations significantly change the spatial pattern of local hydrometeorology, especially convection, clouds and precipitation. The primary research question now is can these changes in local hydrometeorology affect vegetation growth in the clearings. If so, that would be a clear indication that land-atmosphere feedbacks can affect vegetation recovery in fragmented forests. A computationally-efficient modeling tool consisting of a mesoscale atmospheric model dynamically coupled with a plant growth model has been specifically developed to identify the atmospheric feedback pathways. Preliminary experiments focus on the seasonal-scale feedbacks during the dry season. Results show that temperature, incoming shortwave and precipitation are the three primary drivers through which the feedbacks operate. Increasing temperature increases respiratory losses generating a positive feedback. Increased cloud cover reduces incoming PAR and photosynthesis, resulting in a positive feedback. Increased precipitation reduces water stress and promotes growth resulting in a negative feedback. The net effect is a combination of these 3 feedback loops. These findings can significantly improve our understanding of ecosystem resiliency in disturbed tropical forests.

The origin of traveling waves in an emperor penguin huddle

International Nuclear Information System (INIS)

Gerum, R C; Fabry, B; Metzner, C; Zitterbart, D P; Beaulieu, M; Ancel, A

2013-01-01

Emperor penguins breed during the Antarctic winter and have to endure temperatures as low as −50 °C and wind speeds of up to 200 km h −1 . To conserve energy, they form densely packed huddles with a triangular lattice structure. Video recordings from previous studies revealed coordinated movements in regular wave-like patterns within these huddles. It is thought that these waves are triggered by individual penguins that locally disturb the huddle structure, and that the traveling wave serves to remove the lattice defects and restore order. The mechanisms that govern wave propagation are currently unknown, however. Moreover, it is unknown if the waves are always triggered by the same penguin in a huddle. Here, we present a model in which the observed wave patterns emerge from simple rules involving only the interactions between directly neighboring individuals, similar to the interaction rules found in other jammed systems, e.g. between cars in a traffic jam. Our model predicts that a traveling wave can be triggered by a forward step of any individual penguin located within a densely packed huddle. This prediction is confirmed by optical flow velocimetry of the video recordings of emperor penguins in their natural habitat. (paper)

Information impact on quality of travel choices: analysis of data from a multimodal travel simulator

NARCIS (Netherlands)

Chorus, C.G.; Arentze, T.A.; Timmermans, H.J.P.; Silva, da A.N.R.; Souza, de L.C.L.

2007-01-01

This paper investigates the impact of travel information on the quality of travel choices. It distinguishes itself from earlier studies on this topic by empirically investigating the impact of a variety of travel information types on the quality of observed multimodal travel choices. Choice quality

Drug use, travel and HIV risk.

Science.gov (United States)

Lee, D; Bell, D C; Hinojosa, M

2002-08-01

A study was conducted to examine the travel experiences of a community sample of 160 drug users and 44 non-users recruited as part of a study of HIV risk. Of the sample, 47% (96/204) reported intercity travel in the previous ten years. Results showed that men were more likely to travel than women, Anglos more than minorities, and young persons more than old. When travellers testing HIV-seropositive (n = 13) were compared with seronegative travellers, HIV-positive travellers reported more sex while travelling than HIV-negative persons, but virtually all of the difference reported involved sex with condoms. There were no significant differences in sex risk behaviours while travelling between drug users and non-drug users, or in sex risk behaviors between drug injectors and non-injectors. Travellers had fewer injection partners while travelling than they had while at home. There was also a significant difference in number of sex partners with whom a condom was not used, with fewer sex partners while travelling.

Analysis of ionospheric disturbances associated with powerful cyclones in East Asia and North America

Science.gov (United States)

Li, Wang; Yue, Jianping; Yang, Yang; Li, Zhen; Guo, Jinyun; Pan, Yi; Zhang, Kefei

2017-08-01

East Asia and North America are the regions most heavily affected by powerful cyclones. In this paper we investigate the morphological characteristics of ionospheric disturbances induced by cyclones in different continents. The global ionosphere map supplied by the Center for Orbit Determination in Europe (CODE), International Reference Ionosphere Model (IRI) 2012, and Wallops Island ionosonde station data are used to analyse the ionospheric variations during powerful typhoons/hurricanes in East Asia and North America, respectively. After eliminating the ionospheric anomalies due to the solar-terrestrial environment, the total electron content (TEC) time series over the point with maximum wind speed is detected by the sliding interquartile range method. The results indicate that significant ionospheric disturbances are observed during powerful tropical cyclones in East Asia and North America, respectively, and that all the ionospheric anomalies are positive. In addition, the extent and magnitude of travelling ionospheric disturbances are associated with the category of tropical cyclone, and the extent of TEC anomalies in longitude is more pronounced than that in latitude. Furthermore, the maximum ionospheric anomaly does not coincide with the eye of the storm, but appears in the region adjacent to the centre. This implies that ionospheric disturbances at the edges of cyclones are larger than those in the eye of the winds. The phenomenon may be associated with the gravity waves which are generated by strong convective cells that occur in the spiral arms of tropical cyclones. This comprehensive analysis suggests that the presence of powerful typhoons/hurricanes may be a possible source mechanism for ionospheric anomalies.

The atmospheric extinction of light

International Nuclear Information System (INIS)

Hughes, Stephen W; Powell, Sean; Carroll, Joshua; Cowley, Michael

2016-01-01

An experiment is described that enables students to understand the properties of atmospheric extinction due to Rayleigh scattering. The experiment requires the use of red, green and blue lasers attached to a travelling microscope or similar device. The laser beams are passed through an artificial atmosphere, made from milky water, at varying depths, before impinging on either a light meter or a photodiode integral to a Picotech Dr. DAQ ADC. A plot of measured spectral intensity verses depth reveals the contribution Rayleigh scattering has to the extinction coefficient. For the experiment with the light meter, the extinction coefficients for red, green and blue light in the milky sample of water were 0.27, 0.36 and 0.47 cm −1 respectively and 0.032, 0.037 and 0.092 cm −1 for the Picotech Dr. DAQ ADC. (paper)

Carlson Wagonlit Travel

CERN Multimedia

Carlson Wagonlit Travel

2005-01-01

Dear customers, On 3 January we informed you that the airlines had decided to cease paying commission to travel agencies in Switzerland. This measure has since been progressively introduced, with rare exceptions. Consequently, in agreement with CERN, we are obliged to apply new transaction fees for private travel, with immediate effect. Carlson Wagonlit Travel (CWT) offers: A personalized, professional and competent consultancy service To seek the most economical and best solution adapted to your needs Neutrality in comparing prices and benefits Additional information concerning e.g. visa regulations, insurance, vaccinations, etc. Support in the event of problems We draw your attention to the fact that, in spite of the increase, these prices remain very competitive on today's market. Thank you for your trust and understanding. Yours truly, Carlson Wagonlit Travel CERN agency

Hepatitis B vaccination in travelers

NARCIS (Netherlands)

Sonder, Gerard J. B.

2008-01-01

An increasing number of travelers travel to hepatitis B-endemic countries. In travel medicine, vaccinations should be advised according to risks. The actual incidence of hepatitis B infection in short-term tourists is very low and probably not higher than it is for people who do not travel. There is

Trends and characteristics among HIV-infected and diabetic travelers seeking pre-travel advice

NARCIS (Netherlands)

Elfrink, Floor; van den Hoek, Anneke; Sonder, Gerard J. B.

2014-01-01

The number of individuals with a chronic disease increases. Better treatment options have improved chronic patients' quality of life, likely increasing their motivation for travel. This may have resulted in a change in the number of HIV-infected travelers and/or travelers with Diabetes Mellitus (DM)

An introduction to atmospheric gravity waves

CERN Document Server

Nappo, Carmen J

2012-01-01

Gravity waves exist in all types of geophysical fluids, such as lakes, oceans, and atmospheres. They play an important role in redistributing energy at disturbances, such as mountains or seamounts and they are routinely studied in meteorology and oceanography, particularly simulation models, atmospheric weather models, turbulence, air pollution, and climate research. An Introduction to Atmospheric Gravity Waves provides readers with a working background of the fundamental physics and mathematics of gravity waves, and introduces a wide variety of applications and numerous recent advances. Nappo provides a concise volume on gravity waves with a lucid discussion of current observational techniques and instrumentation.An accompanying website contains real data, computer codes for data analysis, and linear gravity wave models to further enhance the reader's understanding of the book's material. Companion web site features animations and streaming video Foreword by George Chimonas, a renowned expert on the interac...

Effectiveness of pre-travel consultation in the prevention of travel-related diseases: a retrospective cohort study.

Science.gov (United States)

Tafuri, Silvio; Guerra, Rocco; Gallone, Maria Serena; Cappelli, Maria Giovanna; Lanotte, Serafina; Quarto, Michele; Germinario, Cinzia

2014-01-01

This study aims to evaluate the effectiveness of pre-travel counselling carried out in Travel Clinics. This is a retrospective cohort. Three hundred international travellers were enrolled; 150 people were from users of Bari Travel Clinic, 150 were users of a travel agency. Enrolled subjects were interviewed using a questionnaire. The average age of the enrolled subjects was 37.5 ± 13.9, without statistically significant differences between the two groups. 86% of cases and 19.3% of the controls reported the use of anti-malaria prophylaxis (p Travel Clinic users, 6% reported diarrhoea and these figures were 27% in the control group (p study demonstrated the effectiveness of pre-travel counselling; in the future, new studies must investigate the cost-effectiveness of pre-travel prevention measures.

Risk factors for infections in international travelers: an analysis of travel-related notifiable communicable diseases.

Science.gov (United States)

Baer, Atar; Libassi, Lisa; Lloyd, Jennifer K; Benoliel, Eileen; Brucker, Rachel; Jones, Megan Q; Kwan-Gett, Tao Sheng; McKeirnan, Shelly; Pecha, Monica; Rietberg, Krista; Serafin, Lauri; Walkinshaw, Lina P; Duchin, Jeffrey S

2014-01-01

We sought to describe travel-related illness among our residents and gain insight into targeting pre-travel health advice to prevent travel-related illness. A supplemental travel questionnaire was developed and administered for cases with a legally notifiable communicable disease reported in 2011-2012, who spent at least part of their exposure period outside the United States. Among 451 cases meeting the eligibility criteria, 259 were interviewed. Forty four percent reported receiving pre-travel advice. Two-thirds adhered fully with risk behavior recommendations; 94% followed immunization recommendations partially or fully; and 84% adhered fully with malaria prophylaxis recommendations. The primary reasons for not obtaining pre-travel advice were being unaware of the need (47.5%), or believing they already knew what to do (34.5%). Adults (OR = 2.8, 95% CI = 1.4-5.5), males (OR = 1.8, 95% CI = 1.1-3.0), those born outside the United States (OR = 2.0, 95% CI = 1.1-3.7), and those with planning time under two weeks (OR = 4.8, 95% CI = 1.5-15.9) or travel duration less than 7 days (OR = 7.9, 95% CI = 3.0-20.9) were more likely to travel without seeking pre-travel advice. The majority of cases reported not receiving pre-travel advice. Understanding the predictors of failure to receive pre-travel advice may help target public health prevention efforts. Copyright © 2014 Elsevier Ltd. All rights reserved.

Health challenges of young travelers visiting friends and relatives compared with those traveling for other purposes.

Science.gov (United States)

Han, Pauline; Yanni, Emad; Jentes, Emily S; Hamer, Davidson H; Chen, Lin H; Wilson, Mary E; Macleod, William B; Ooi, Winnie W; Kogelman, Laura; Karchmer, Adolf W; Barnett, Elizabeth D

2012-09-01

The study objective was to assess differences in demographics and travel health challenges between youths ≤18 years old traveling internationally to visit friends and relatives (VFRs) compared with those traveling for other purposes (non-VFR). The Boston Area Travel Medicine Network consists of 5 clinics collecting anonymous data from international pretravel consultations. Data on all travelers ≤18 years of age seen between January 2008 and July 2010 were used. VFRs were compared with non-VFRs on demographics, primary language, trip characteristics, travel vaccinations administered, malaria prophylaxis and antidiarrheal medications prescribed. Thirty-five percent (610/1731) listed VFR as their purpose of travel. Almost half of VFRs were travel to countries that were yellow fever holoendemic, had malaria risk and were high-risk for typhoid (44% versus 20%, 39% versus 12%, 25% versus 15%, P travel-related morbidity, healthcare providers should be prepared to give travel advice to parents of VFR infants and children, particularly those US-born VFRs with foreign-born parents, regarding antimalarial and antidiarrheal medications and preventing yellow fever, malaria and typhoid.

Travel Time Reliability in Indiana

OpenAIRE

Martchouk, Maria; Mannering, Fred L.; Singh, Lakhwinder

2010-01-01

Travel time and travel time reliability are important performance measures for assessing traffic condition and extent of congestion on a roadway. This study first uses a floating car technique to assess travel time and travel time reliability on a number of Indiana highways. Then the study goes on to describe the use of Bluetooth technology to collect real travel time data on a freeway and applies it to obtain two weeks of data on Interstate 69 in Indianapolis. An autoregressive model, estima...

Travel risk behaviours and uptake of pre-travel health preventions by university students in Australia.

Science.gov (United States)

Heywood, Anita E; Zhang, Meng; MacIntyre, C Raina; Seale, Holly

2012-02-17

Forward planning and preventative measures before travelling can significantly reduce the risk of many vaccine preventable travel-related infectious diseases. Higher education students may be at an increased risk of importing infectious disease as many undertake multiple visits to regions with higher infectious disease endemicity. Little is known about the health behaviours of domestic or international university students, particularly students from low resource countries who travel to high-resource countries for education. This study aimed to assess travel-associated health risks and preventative behaviours in a sample of both domestic and international university students in Australia. In 2010, a 28 item self-administered online survey was distributed to students enrolled at the University of New South Wales, Sydney, Australia. Multiple methods of distributing links to the online survey were utilised. The survey examined the international travel history, travel intentions, infection control behaviours and self-reported vaccination history. A total of 1663 respondents completed the online survey, 22.1% were international students and 83.9% were enrolled at an undergraduate level. Half had travelled internationally in the previous 12 months, with 69% of those travelling only once during that time with no difference in travel from Australia between domestic and international students (p = 0.8). Uptake of pre-travel health advice was low overall with 68% of respondents reporting they had not sought any advice from a health professional prior to their last international trip. Domestic students were more likely to report uptake of a range of preventative travel health measures compared to international students, including diarrhoeal medication, insect repellent, food avoidance and condoms (P students reported low risk perception of travel threats and a low corresponding concern for these threats. Our study highlights the need to educate students about the risk

Joint analysis of short-period variations of ionospheric parameters in Siberia and the Far East and processes of the tropical cyclogenesis

Science.gov (United States)

Chernigovskaya, M. A.; Kurkin, V. I.; Orlov, I. I.; Sharkov, E. A.; Pokrovskaya, I. V.

2009-04-01

In this work a possibility of manifestation of strong meteorological disturbances in the Earth lower atmosphere in variations of ionospheric parameters in the zone remote from the disturbance source has been studied. The spectral analysis of short-period variations (about ten minutes, hours) in maximum observed frequencies (MOF) of one-skip signals of oblique sounding has been carried out. These variations were induced by changes in the upper atmosphere parameters along the Magadan-Irkutsk oblique-incidence sounding path on the background of diurnal variations in the parameter under study. Data on MOF measurements with off-duty factor approximately 5 min in equinoxes (September, March) of 2005-2007 were used. The analysis was made using the improved ISTP-developed technique of determining periodicities in time series. The increase of signal spectrum energy at certain frequencies is interpreted as manifestation of traveling ionospheric disturbances (TID) associated with propagation of internal gravity waves in the atmosphere. The analysis revealed TIDs of temporal scales under consideration. The question concerning localization of possible sources of revealed disturbances is discussed. Troposphere meteorological disturbances giant in their energy (tropical cyclones, typhoon) are considered as potential sources of observable TIDs. The needed information on tropical cyclones that occurred in the north area of the Indian Ocean, south-west and central areas of the Pacific Ocean in 2005-2007 is taken from the electron base of satellite data on the global tropical cyclogenesis "Global-TC" (ISR RAS). In order to effectively separate disturbances associated with the magnetospheric-ionospheric interaction and disturbances induced by the lower atmosphere influence on the upper atmosphere, we analyze the tropical cyclogenesis events that occurred in quiet helio-geomagnetic conditions. The study was supported by the Program of RAS Presidium N 16 (Part 3) and the RFBR Grant N 08-05-00658.

Knowledge, attitudes, and practices evaluation about travel medicine in international travelers and medical students in Chile.

Science.gov (United States)

Guerrero-Lillo, Lisette; Medrano-Díaz, Jorge; Pérez, Carmen; Chacón, Rodrigo; Silva-Urra, Juan; Rodriguez-Morales, Alfonso J

2009-01-01

Because information about travel medicine in Chile is lacking, a knowledge, attitudes, and practices evaluation in international travelers and medical students was done. The travelers and medical students did not know the travel medicine and sanitary conditions of their destinations, although they perceived travel-associated health risks, but <10% had any vaccination and 5% got sick during international trips.

Longitudinal effects of ionospheric responses to substorms at middle and lower latitudes: a case study

Directory of Open Access Journals (Sweden)

X. Pi

1995-08-01

Full Text Available An ionospheric model is used to simulate total electron content (TEC disturbance events observed at middle and lower latitude sites near 75°W and 7°E longitudes. Within this longitudinal range, daytime TEC disturbances show patterns that are correlated with substrom activity seen in both auroral electrojet and ring current behavior. In modeling studies of the observed ionospheric effects, both electric field and neutral wind perturbations are examined as possible mechanisms. The morphological features of the required electric field perturbations near drawn and dusk are compared with those at other times to examine the local time characteristics of magnetospheric influence. Large-scale traveling atmospheric disturbances (TADs, an alternative candidate for the disturbance source, are also characterized and compared with known thermospheric behavior.

State of the Carbon Cycle - Consequences of Rising Atmospheric CO2

Science.gov (United States)

Moore, D. J.; Cooley, S. R.; Alin, S. R.; Brown, M. E.; Butman, D. E.; French, N. H. F.; Johnson, Z. I.; Keppel-Aleks, G.; Lohrenz, S. E.; Ocko, I.; Shadwick, E. H.; Sutton, A. J.; Potter, C. S.; Yu, R. M. S.

2016-12-01

The rise of atmospheric CO2, largely attributable to human activity through fossil fuel emissions and land-use change, has been dampened by carbon uptake by the ocean and terrestrial biosphere. We outline the consequences of this carbon uptake as direct and indirect effects on terrestrial and oceanic systems and processes for different regions of North America and the globe. We assess the capacity of these systems to continue to act as carbon sinks. Rising CO2 has decreased seawater pH; this process of ocean acidification has impacted some marine species and altered fundamental ecosystem processes with further effects likely. In terrestrial ecosystems, increased atmospheric CO2 causes enhanced photosynthesis, net primary production, and increased water-use efficiency. Rising CO2 may change vegetation composition and carbon storage, and widespread increases in water use efficiency likely influence terrestrial hydrology and biogeochemical cycling. Consequences for human populations include changes to ecosystem services including cultural activities surrounding land use, agricultural or harvesting practices. Commercial fish stocks have been impacted and crop production yields have been changed as a result of rising CO2. Ocean and terrestrial effects are contingent on, and feedback to, global climate change. Warming and modified precipitation regimes impact a variety of ecosystem processes, and the combination of climate change and rising CO2 contributes considerable uncertainty to forecasting carbon sink capacity in the ocean and on land. Disturbance regime (fire and insects) are modified with increased temperatures. Fire frequency and intensity increase, and insect lifecycles are disrupted as temperatures move out of historical norms. Changes in disturbance patterns modulate the effects of rising CO2 depending on ecosystem type, disturbance frequency, and magnitude of events. We discuss management strategies designed to limit the rise of atmospheric CO2 and reduce

State of the Carbon Cycle - Consequences of Rising Atmospheric CO2

Science.gov (United States)

Moore, David J.; Cooley, Sarah R.; Alin, Simone R.; Brown, Molly; Butman, David E.; French, Nancy H. F.; Johnson, Zackary I.; Keppel-Aleks; Lohrenz, Steven E.; Ocko, Ilissa;

Traveling and Asthma

Science.gov (United States)

... Videos for Educators Search English Español Traveling and Asthma KidsHealth / For Kids / Traveling and Asthma Print en ... pack it, too. How Can I Avoid My Asthma Triggers? Staying at a hotel Ask for a ...

Disturbance observer-based L1 robust tracking control for hypersonic vehicles with T-S disturbance modeling

Directory of Open Access Journals (Sweden)

Yang Yi

2016-11-01

Full Text Available This article concerns a disturbance observer-based L1 robust anti-disturbance tracking algorithm for the longitudinal models of hypersonic flight vehicles with different kinds of unknown disturbances. On one hand, by applying T-S fuzzy models to represent those modeled disturbances, a disturbance observer relying on T-S disturbance models can be constructed to track the dynamics of exogenous disturbances. On the other hand, L1 index is introduced to analyze the attenuation performance of disturbance for those unmodeled disturbances. By utilizing the existing convex optimization algorithm, a disturbance observer-based proportional-integral-controlled input is proposed such that the stability of hypersonic flight vehicles can be ensured and the tracking error for velocity and altitude in hypersonic flight vehicle models can converge to equilibrium point. Furthermore, the satisfactory disturbance rejection and attenuation with L1 index can be obtained simultaneously. Simulation results on hypersonic flight vehicle models can reflect the feasibility and effectiveness of the proposed control algorithm.

Travelling Concepts

DEFF Research Database (Denmark)

Simonsen, Karen-Margrethe

2013-01-01

Review of "Travelling Concepts, Metaphors, and Narratives: Literary and Cultural Studies in an Age of Interdisciplinary Research" ed. by Sibylle Baumgarten, Beatrice Michaelis and Ansagar Nünning, Trier; Wissenschaftlicher Verlag Trier, 2012......Review of "Travelling Concepts, Metaphors, and Narratives: Literary and Cultural Studies in an Age of Interdisciplinary Research" ed. by Sibylle Baumgarten, Beatrice Michaelis and Ansagar Nünning, Trier; Wissenschaftlicher Verlag Trier, 2012...

Measuring Temperature-Dependent Propagating Disturbances in Coronal Fan Loops Using Multiple SDO-AIA Channels and Surfing Transform Technique

Science.gov (United States)

Uritskiy, Vadim M.; Davila, Joseph M.; Viall, Nicholeen M.; Ofman, Leon

2013-01-01

A set of co-aligned high resolution images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) is used to investigate propagating disturbances (PDs) in warm fan loops at the periphery of a non-flaring active region NOAA AR 11082. To measure PD speeds at multiple coronal temperatures, a new data analysis methodology is proposed enabling quantitative description of sub visual coronal motions with low signal-to-noise ratios of the order of 0.1. The technique operates with a set of one-dimensional surfing signals extracted from position-timeplots of several AIA channels through a modified version of Radon transform. The signals are used to evaluate a two-dimensional power spectral density distribution in the frequency - velocity space which exhibits a resonance in the presence of quasi-periodic PDs. By applying this analysis to the same fan loop structures observed in several AIA channels, we found that the traveling velocity of PDs increases with the temperature of the coronal plasma following the square root dependence predicted for the slow mode magneto-acoustic wave which seems to be the dominating wave mode in the studied loop structures. This result extends recent observations by Kiddie et al. (2012) to a more general class of fan loop systems not associated with sunspots and demonstrating consistent slow mode activity in up to four AIA channels.

Integrating Remote Sensing, Field Observations, and Models to Understand Disturbance and Climate Effects on the Carbon Balance of the West Coast U.S.

Energy Technology Data Exchange (ETDEWEB)

Cohen, Warren [USDA Forest Service

2014-07-03

As an element of NACP research, the proposed investigation is a two pronged approach that derives and evaluates a regional carbon (C) budget for Oregon, Washington, and California. Objectives are (1) Use multiple data sources, including AmeriFlux data, inventories, and multispectral remote sensing data to investigate trends in carbon storage and exchanges of CO2 and water with variation in climate and disturbance history; (2) Develop and apply regional modeling that relies on these multiple data sources to reduce uncertainty in spatial estimates of carbon storage and NEP, and relative contributions of terrestrial ecosystems and anthropogenic emissions to atmospheric CO2 in the region; (3) Model terrestrial carbon processes across the region, using the Biome-BGC terrestrial ecosystem model, and an atmospheric inverse modeling approach to estimate variation in rate and timing of terrestrial uptake and feedbacks to the atmosphere in response to climate and disturbance.

Impact of advice given to travelers concerning the main infectious risks associated with traveling in the tropics.

Science.gov (United States)

Lestelle, C; Aymeric, S; Maakaroun-Vermesse, Z; Pouliquen, A; Bernard, L; Chandenier, J; Grammatico-Guillon, L

2015-06-01

The prevention of sanitary risks related to traveling in the tropics implies delivering a large amount of information to travelers. The objective of our study was to assess the knowledge acquired by travelers during a pre-travel consultation. A before and after study was conducted among 202 travelers having consulted at the Tours international vaccine center. We used self-administrated questionnaires (score out of 100 marks) concerning diet, hygiene, anti-vectorial prevention (AVP), and sexual-transmitted infections (STI). The scores obtained before and after consultation were compared globally and for each topic. The travelers' global knowledge had improved after consultation (66.1 vs. 75.5%; P traveling compared to humanitarian mission prepared ahead of departure time). The recommendations for diet were less well acquired in travelers > 50 years of age than in those travel consultation improves the travelers' knowledge for the main prevention measures but does not allow them to acquire all required knowledge. Taking into account the travelers' initial knowledge and their ability to learn could improve the impact of the pre-travel consultation. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

41 CFR 301-71.105 - Must we issue a written or electronic travel authorization in advance of travel?

Science.gov (United States)

2010-07-01

... or electronic travel authorization in advance of travel? 301-71.105 Section 301-71.105 Public Contracts and Property Management Federal Travel Regulation System TEMPORARY DUTY (TDY) TRAVEL ALLOWANCES AGENCY RESPONSIBILITIES 71-AGENCY TRAVEL ACCOUNTABILITY REQUIREMENTS Travel Authorization § 301-71.105...

Propagating intensity disturbances in polar corona as seen from AIA/SDO

Science.gov (United States)

Krishna Prasad, S.; Banerjee, D.; Gupta, G. R.

2011-04-01

Context. Polar corona is often explored to find the energy source for the acceleration of the fast solar wind. Earlier observations show omni-presence of quasi-periodic disturbances, traveling outward, which is believed to be caused by the ubiquitous presence of outward propagating waves. These waves, mostly of compressional type, might provide the additional momentum and heat required for the fast solar wind acceleration. It has been conjectured that these disturbances are not due to waves but high speed plasma outflows, which are difficult to distinguish using the current available techniques. Aims: With the unprecedented high spatial and temporal resolution of AIA/SDO, we search for these quasi-periodic disturbances in both plume and interplume regions of the polar corona. We investigate their nature of propagation and search for a plausible interpretation. We also aim to study their multi-thermal nature by using three different coronal passbands of AIA. Methods: We chose several clean plume and interplume structures and studied the time evolution of specific channels by making artificial slits along them. Taking the average across the slits, space-time maps are constructed and then filtration techniques are applied to amplify the low-amplitude oscillations. To suppress the effect of fainter jets, we chose wider slits than usual. Results: In almost all the locations chosen, in both plume and interplume regions we find the presence of propagating quasi-periodic disturbances, of periodicities ranging from 10-30 min. These are clearly seen in two channels and in a few cases out to very large distances (≈250″) off-limb, almost to the edge of the AIA field of view. The propagation speeds are in the range of 100-170 km s-1. The average speeds are different for different passbands and higher in interplume regions. Conclusions: Propagating disturbances are observed, even after removing the effects of jets and are insensitive to changes in slit width. This indicates

Examining the Relationship between Online Travel Agency Information and Traveler Destination Transaction Decisions

Science.gov (United States)

Yerby, Dennis

2012-01-01

The purpose of this quantitative study was to examine the role that available Online Travel Agency (OTA) destination information may have on a traveler's perceptions and intent in transaction decisions with that respective OTA. Specifically, this research examined a pleasure traveler's transaction perceptions and intentions with an OTA…

Travel Agent Course Outline.

Science.gov (United States)

British Columbia Dept. of Education, Victoria.

Written for college entry-level travel agent training courses, this course outline can also be used for inservice training programs offered by travel agencies. The outline provides information on the work of a travel agent and gives clear statements on what learners must be able to do by the end of their training. Material is divided into eight…

Travel time variability and rational inattention

DEFF Research Database (Denmark)

Fosgerau, Mogens; Jiang, Gege

2017-01-01

This paper sets up a rational inattention model for the choice of departure time for a traveler facing random travel time. The traveler chooses how much information to acquire about the travel time out-come before choosing departure time. This reduces the cost of travel time variability compared...

Monitoring Travel Time Reliability on Freeways

NARCIS (Netherlands)

Tu, Huizhao

2008-01-01

Travel time and travel time reliability are important attributes of a trip. The current measures of reliability have in common that in general they all relate to the variability of travel times. However, travel time reliability does not only rely on variability but also on the stability of travel

Enquiries to the United Kingdom National Travel Advice Line by healthcare professionals regarding immunocompromised travellers.

Science.gov (United States)

Allen, Joanna E; Patel, Dipti

2016-03-01

People who travel while immunocompromised are more at risk of serious travel-related infection. Their condition, medications or treatments can contraindicate, decrease the effectiveness of or increase the toxicity of vaccinations or malaria chemoprophylaxis. Therefore, immunocompromised travellers require careful assessment and specialized pre-travel advice. The aims of this study were to investigate enquiries by healthcare professionals (HCPs) to the UK National Travel Health Network and Centre (NaTHNaC) advice line regarding travellers with immunocompromise and to identify their most common concerns. Documentation for all calls taken by advisers at the London office during 2013 was reviewed. Of the 4910 enquiries to the London NaTHNaC advice line, 397 calls concerned immunocompromised travellers (8.1%). The majority of immunocompromised travellers were planning to visit Sub-Saharan Africa (53%) for the purpose of tourism (43%). Sixty-seven percent of enquiries concerned vaccine use, 11% were about malaria chemoprophylaxis, 20% were about both and 2% were for other reasons. Causes of immunocompromise included inflammatory or autoimmune conditions (43%), cancer (18%), splenic dysfunction (13%), immunosuppressive drugs (12%), human immunodeficiency virus (11%), primary immunodeficiency (1%), neutropenia (0.5%) and thymus abnormalities (0.5%). There were frequent enquires to the advice line by UK HCPs regarding immunocompromised travellers. The travellers in this study had a wide range of underlying medical conditions and varying levels of immunocompromise. These enquiries may reflect a lack of clarity in current national guidelines, difficulties in interpreting them or both. Establishing the reasons for these deficiencies as well as the reasons behind UK HCP concerns and lack of confidence requires further investigation. This research has highlighted potential knowledge gaps and will help inform future guidance and educational activities for UK HCPs advising

Travel Behavior Change in Older Travelers: Understanding Critical Reactions to Incidents Encountered in Public Transport

Directory of Open Access Journals (Sweden)

Catherine Sundling

2015-11-01

Full Text Available Accessibility of travel may be better understood if psychological factors underlying change in travel behavior are known. This paper examines older (65+ travelers’ motives for changing their travel behavior. These changes are grounded in critical incidents earlier encountered in public-transport travel. A scientific framework is developed based on cognitive and behavioral theory. In 29 individual interviews, travelers’ critical reactions (i.e., cognitive, emotional, and/or behavioral to 77 critical incidents were examined. By applying critical incident technique (CIT, five reaction themes were identified that had generated travel-behavior change: firm restrictions, unpredictability, unfair treatment, complicated trips, and earlier adverse experiences. To improve older travelers’ access to public transport, key findings were: (a service must be designed so as to strengthen the feeling of being in control throughout the journey; (b extended personal service would increase predictability in the travel chain and decrease travel complexity; consequently, (c when designing new services and making effective accessibility interventions, policy makers should consider and utilize underlying psychological factors that could direct traveler behavior.

Travel Behavior Change in Older Travelers: Understanding Critical Reactions to Incidents Encountered in Public Transport

Science.gov (United States)

Sundling, Catherine

2015-01-01

Accessibility of travel may be better understood if psychological factors underlying change in travel behavior are known. This paper examines older (65+) travelers’ motives for changing their travel behavior. These changes are grounded in critical incidents earlier encountered in public-transport travel. A scientific framework is developed based on cognitive and behavioral theory. In 29 individual interviews, travelers’ critical reactions (i.e., cognitive, emotional, and/or behavioral) to 77 critical incidents were examined. By applying critical incident technique (CIT), five reaction themes were identified that had generated travel-behavior change: firm restrictions, unpredictability, unfair treatment, complicated trips, and earlier adverse experiences. To improve older travelers’ access to public transport, key findings were: (a) service must be designed so as to strengthen the feeling of being in control throughout the journey; (b) extended personal service would increase predictability in the travel chain and decrease travel complexity; consequently, (c) when designing new services and making effective accessibility interventions, policy makers should consider and utilize underlying psychological factors that could direct traveler behavior. PMID:26593935

Time-use and well-being impacts of travel-to-work and travel-for-work

OpenAIRE

Wheatley, D; Bickerton, C

2016-01-01

This article contributes to understanding of the complex patterns of travel-to-work and travel-for-work which \\ud increasingly characterize highly skilled employment, using 2015 data from a UK Midlands study comprising an online survey and follow-up interviews. Travel-to-work essentially lengthens the working day, and is difficult to use productively, especially when commuting by car. Travel-for-work, by contrast, results in intense schedules \\ud especially when requiring overnight stays. Own...

49 CFR 229.55 - Piston travel.

Science.gov (United States)

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Piston travel. 229.55 Section 229.55... Piston travel. (a) Brake cylinder piston travel shall be sufficient to provide brake shoe clearance when... piston travel may not exceed 11/2 inches less than the total possible piston travel. The total possible...

Travel risk behaviours and uptake of pre-travel health preventions by university students in Australia

Directory of Open Access Journals (Sweden)

Heywood Anita E

2012-02-01

Full Text Available Abstract Background Forward planning and preventative measures before travelling can significantly reduce the risk of many vaccine preventable travel-related infectious diseases. Higher education students may be at an increased risk of importing infectious disease as many undertake multiple visits to regions with higher infectious disease endemicity. Little is known about the health behaviours of domestic or international university students, particularly students from low resource countries who travel to high-resource countries for education. This study aimed to assess travel-associated health risks and preventative behaviours in a sample of both domestic and international university students in Australia. Methods In 2010, a 28 item self-administered online survey was distributed to students enrolled at the University of New South Wales, Sydney, Australia. Multiple methods of distributing links to the online survey were utilised. The survey examined the international travel history, travel intentions, infection control behaviours and self-reported vaccination history. Results A total of 1663 respondents completed the online survey, 22.1% were international students and 83.9% were enrolled at an undergraduate level. Half had travelled internationally in the previous 12 months, with 69% of those travelling only once during that time with no difference in travel from Australia between domestic and international students (p = 0.8. Uptake of pre-travel health advice was low overall with 68% of respondents reporting they had not sought any advice from a health professional prior to their last international trip. Domestic students were more likely to report uptake of a range of preventative travel health measures compared to international students, including diarrhoeal medication, insect repellent, food avoidance and condoms (P Conclusions Our study highlights the need to educate students about the risk associated with travel and improve preventative

Preface: Impacts of extreme climate events and disturbances on carbon dynamics

Science.gov (United States)

Xiao, Jingfeng; Liu, Shuguang; Stoy, Paul C.

2016-01-01

The impacts of extreme climate events and disturbances (ECE&D) on the carbon cycle have received growing attention in recent years. This special issue showcases a collection of recent advances in understanding the impacts of ECE&D on carbon cycling. Notable advances include quantifying how harvesting activities impact forest structure, carbon pool dynamics, and recovery processes; observed drastic increases of the concentrations of dissolved organic carbon and dissolved methane in thermokarst lakes in western Siberia during a summer warming event; disentangling the roles of herbivores and fire on forest carbon dioxide flux; direct and indirect impacts of fire on the global carbon balance; and improved atmospheric inversion of regional carbon sources and sinks by incorporating disturbances. Combined, studies herein indicate several major research needs. First, disturbances and extreme events can interact with one another, and it is important to understand their overall impacts and also disentangle their effects on the carbon cycle. Second, current ecosystem models are not skillful enough to correctly simulate the underlying processes and impacts of ECE&D (e.g., tree mortality and carbon consequences). Third, benchmark data characterizing the timing, location, type, and magnitude of disturbances must be systematically created to improve our ability to quantify carbon dynamics over large areas. Finally, improving the representation of ECE&D in regional climate/earth system models and accounting for the resulting feedbacks to climate are essential for understanding the interactions between climate and ecosystem dynamics.

Atmospheric Pressure and Abdominal Aortic Aneurysm Rupture: Results From a Time Series Analysis and Case-Crossover Study.

Science.gov (United States)

Penning de Vries, Bas B L; Kolkert, Joé L P; Meerwaldt, Robbert; Groenwold, Rolf H H

2017-10-01

Associations between atmospheric pressure and abdominal aortic aneurysm (AAA) rupture risk have been reported, but empirical evidence is inconclusive and largely derived from studies that did not account for possible nonlinearity, seasonality, and confounding by temperature. Associations between atmospheric pressure and AAA rupture risk were investigated using local meteorological data and a case series of 358 patients admitted to hospital for ruptured AAA during the study period, January 2002 to December 2012. Two analyses were performed-a time series analysis and a case-crossover study. Results from the 2 analyses were similar; neither the time series analysis nor the case-crossover study showed a significant association between atmospheric pressure ( P = .627 and P = .625, respectively, for mean daily atmospheric pressure) or atmospheric pressure variation ( P = .464 and P = .816, respectively, for 24-hour change in mean daily atmospheric pressure) and AAA rupture risk. This study failed to support claims that atmospheric pressure causally affects AAA rupture risk. In interpreting our results, one should be aware that the range of atmospheric pressure observed in this study is not representative of the atmospheric pressure to which patients with AAA may be exposed, for example, during air travel or travel to high altitudes in the mountains. Making firm claims regarding these conditions in relation to AAA rupture risk is difficult at best. Furthermore, despite the fact that we used one of the largest case series to date to investigate the effect of atmospheric pressure on AAA rupture risk, it is possible that this study is simply too small to demonstrate a causal link.

Travel and biologic therapy: travel-related infection risk, vaccine response and recommendations.

Science.gov (United States)

Hall, Victoria; Johnson, Douglas; Torresi, Joseph

2018-01-01

Biologic therapy has revolutionized the management of refractory chronic autoimmune and auto-inflammatory disease, as well as several malignancies, providing rapid symptomatic relief and/or disease remission. Patients receiving biologic therapies have an improved quality of life, facilitating travel to exotic destinations and potentially placing them at risk of a range of infections. For each biologic agent, we review associated travel-related infection risk and expected travel vaccine response and effectiveness. A PUBMED search [vaccination OR vaccine] AND/OR ['specific vaccine'] AND/OR [immunology OR immune response OR response] AND [biologic OR biological OR biologic agent] was performed. A review of the literature was performed in order to develop recommendations on vaccination for patients in receipt of biologic therapy travelling to high-risk travel destinations. There is a paucity of literature in this area, however, it is apparent that travel-related infection risk is increased in patients on biologic therapy and when illness occurs they are at a higher risk of complication and hospitalization. Patients in receipt of biologic agents are deemed as having a high level of immunosuppression-live vaccines, including the yellow fever vaccine, are contraindicated. Inactivated vaccines are considered safe; however, vaccine response can be attenuated by the patient's biologic therapy, thereby resulting in reduced vaccine effectiveness and protection. Best practice requires a collaborative approach between the patient's primary healthcare physician, relevant specialist and travel medicine expert, who should all be familiar with the immunosuppressive and immunomodulatory effects resulting from the biologic therapies. Timing of vaccines should be carefully planned, and if possible, vaccination provided well before established immunosuppression.

Report to the International Global Atmospheric Chemistry Project

Energy Technology Data Exchange (ETDEWEB)

Reisdorf, Jill [University Corporation for Atmospheric Research (UCAR/CPAESS), Boulder, CO (United States); Wiedinmyer, Christine [National Center for Atmospheric Research (NCAR/ACOM), Boulder, CO (United States)

2017-04-21

IGAC’s mission is to facilitate atmospheric chemistry research towards a sustainable world. This is achieved through IGAC’s three focal activities: fostering community, building capacity, and providing leadership. A key component to achieving IGAC’s mission is its developing early career program. These scientists join an international network early in their career that puts the cogs in motion to further facilitate atmospheric chemistry research at an international level for years to come. IGAC’s Science Conference is a primary mechanism for IGAC to build cooperation and disseminate scientific information across its international community. The first IGAC Science Conference was held in 1993 in Eilat, Israel. Since then, IGAC has successfully held fourteen science conferences, consistently becoming a biennial conference starting in 2002. The biennial IGAC Science Conference is regarded as THE international conference on atmospheric chemistry and participation in the conference is typically in the range of 350-650 participants. Since 2004, IGAC has included an Early Career Scientists Program as part of the conference to foster the next generation of scientists. IGAC believes, and has seen, that by allowing scientists to form an international network of colleagues early in their career that future international collaborations in atmospheric chemistry are enhanced. The 2016 IGAC Science Conference Early Career Program consisted of numerous events throughout the week giving these scientists the opportunity to not only create a community amongst themselves, but to also engage and build relationships with senior scientists. In order to support the Early Career Scientists Program, IGAC sought funding from international, regional and local organizations to provide Travel Grants to the conference based on an assessment of both need and merit. This conference summary reports on outcomes of the 2016 IGAC Science Conference and the Early Career Program, which included

Travel time data collection handbook

Science.gov (United States)

1998-03-01

This Travel Time Data Collection Handbook provides guidance to transportation : professionals and practitioners for the collection, reduction, and presentation : of travel time data. The handbook should be a useful reference for designing : travel ti...

The value of travel time variance

OpenAIRE

Fosgerau, Mogens; Engelson, Leonid

2010-01-01

This paper considers the value of travel time variability under scheduling preferences that are de�fined in terms of linearly time-varying utility rates associated with being at the origin and at the destination. The main result is a simple expression for the value of travel time variability that does not depend on the shape of the travel time distribution. The related measure of travel time variability is the variance of travel time. These conclusions apply equally to travellers who can free...

Adolescent school travel: Is online mapping a practical alternative to GPS-assessed travel routes?

DEFF Research Database (Denmark)

Stewart, Tom; Schipperijn, Jasper; Snizek, Bernhard

2017-01-01

AbstractBackground Geographically accurate travel routes are necessary to estimate exposure to the environment and its potential influence on travel behaviour. Although assessing travel behaviours with Global Positioning System (GPS) receivers is increasingly common, these protocols place......-reporting error seems more pronounced for longer routes, and when multiple travel modes are used. Researchers should consider the advantages (e.g., ease of collection) and disadvantages (e.g., lack of temporal information) when deciding if the data obtainable are sufficient to answer their research questions....

Business travel and sustainability. Part III. In: Handbook of Sustainable Travel: People, Society, and Transportation Systems

OpenAIRE

AGUILERA, Anne

2013-01-01

Business travel has been relatively neglected in strategies to promote sustainable travel. A two-stage approach is taken beginning by showing how sustainability of business travel is relevant not only environmentally, but also from an economic and social perspective. On the one hand, this form of travel helps to generate jobs in numerous business sectors, not only in transportation. On the other hand, the social dimension cannot be ignored either, since business travel is often a source of fa...

Response of Nitrogen Leaching to Nitrogen Deposition in Disturbed and Mature Forests of Southern China

Institute of Scientific and Technical Information of China (English)

FANG Yun-Ting; M. YOH; MO Jiang-Ming; P. GUNDERSEN; ZHOU Guo-Yi

2009-01-01

Current nitrogen (N) leaching losses and their responses to monthly N additions were investigated under a disturbed pine (Pinus massoniana) forest and a mature monsoon broadleaf forest in southern China. N leaching losses from both disturbed and mature forests were quite high (14.6 and 29.2 kg N ha-1 year-1, respectively), accounting for 57% and 80% of their corresponding atmospheric N inputs. N leaching losses were substantially increased following the first 1.5 years of N applications in both forests. The average increases induced by the addition of 50 and 100 kg N ha-1 year-1 were 36.5 and 24.9 kg N ha-1 year-1, respectively, in the mature forest, accounting for 73.0% and 24.9% of the annual amount of N added, and 14.2 and 16.8 kg N ha-1 year-1 in the disturbed forest, accounting for 28.4% and 16.8% of the added N. Great N leaching and a fast N leaching response to N additions in the mature forest might result from long-term N accumulation and high ambient N deposition load (greater than 30 kg N ha-1 year-1 over the past 15 years), whereas in the disturbed forest, it might result from the human disturbance and high ambient N deposition load. These results suggest that both disturbed and mature forests in the study region may be sensitive to increasing N deposition.

Travellers and influenza: risks and prevention.

Science.gov (United States)

Goeijenbier, M; van Genderen, P; Ward, B J; Wilder-Smith, A; Steffen, R; Osterhaus, A D M E

2017-01-01

Influenza viruses are among the major causes of serious human respiratory tract infection worldwide. In line with the high disease burden attributable to influenza, these viruses play an important, but often neglected, role in travel medicine. Guidelines and recommendations regarding prevention and management of influenza in travellers are scarce. Of special interest for travel medicine are risk populations and also circumstances that facilitate influenza virus transmission and spread, like travel by airplane or cruise ship and mass gatherings. We conducted a PUBMED/MEDLINE search for a combination of the MeSH terms Influenza virus, travel, mass gathering, large scale events and cruise ship. In addition we gathered guidelines and recommendations from selected countries and regarding influenza prevention and management in travellers. By reviewing these search results in the light of published knowledge in the fields of influenza prevention and management, we present best practice advice for the prevention and management of influenza in travel medicine. Seasonal influenza is among the most prevalent infectious diseases in travellers. Known host-associated risk factors include extremes of age and being immune-compromised, while the most relevant environmental factors are associated with holiday cruises and mass gatherings. Pre-travel advice should address influenza and its prevention for travellers, whenever appropriate on the basis of the epidemiological situation concerned. Preventative measures should be strongly recommended for travellers at high-risk for developing complications. In addition, seasonal influenza vaccination should be considered for any traveller wishing to reduce the risk of incapacitation, particularly cruise ship crew and passengers, as well as those participating in mass gatherings. Besides advice concerning preventive measures and vaccination, advice on the use of antivirals may be considered for some travellers. © International Society of

APPROXIMATED NUMERICAL MODELING OF DYNAMIC MOVEMENT OF THE AIRCRAFT IN TURBULENT ATMOSPHERE ON APPROACH ZONE TO THE AIRPORT

Directory of Open Access Journals (Sweden)

A. B. Bayramov

2015-01-01

Full Text Available Application of dynamic modeling method upon ECAST to assess reactions of aircraft of Airbus type to random atmospheric disturbances without the use of Monte-Carlo method is considered. Application of the method will determine the significance of aircraft reactions to these disturbances, which will help in predicting the flight safety level.

A stated adaptation approach to assess changes in individuals’ activity-travel behavior in presence of personalized travel information

NARCIS (Netherlands)

Parvaneh, Zahra; Arentze, Theo; Timmermans, Harry

2014-01-01

The rapid and inevitable growth of availability of travel information for travellers has increased expectations among policy makers about the benefits of travel information. It is increasingly expected that providing advanced travel information can trigger particular travel behaviors that would

Post-travel screening of asymptomatic long-term travelers to the tropics for intestinal parasites using molecular diagnostics.

Science.gov (United States)

Soonawala, Darius; van Lieshout, Lisette; den Boer, Marion A M; Claas, Eric C J; Verweij, Jaco J; Godkewitsch, André; Ratering, Marchel; Visser, Leo G

2014-05-01

The incidence of asymptomatic travel-related parasitic infection is uncertain. Previous studies did not distinguish new incident infections, from past infections. Regardless of symptoms, we performed multiplex real-time polymerase chain reaction on pre- and post-travel stool samples of Dutch long-term travelers to the (sub)tropics. Serological screening for Schistosoma spp. was only performed in travelers to sub-Saharan Africa. In total, 679 travelers were included in the study. The follow-up rate was 82% (556 of 679). Participants' median travel duration was 12 weeks. There was one incident infection with Strongyloides stercoralis; there were none with Entamoeba histolytica, 4 with Cryptosporidium spp. (1%), and 22 with Giardia lamblia (4%). Nine of 146 travelers (6%) seroconverted for Schistosoma spp. Routine screening of stool samples for parasitic infection is not indicated for asymptomatic people, who travel to the (sub)tropics for up to 3 months. Screening for Schistosoma spp. should be offered to travelers with fresh-water contact in endemic regions.

Fecal-orally transmitted diseases among travelers are decreasing due to better hygienic standards at travel destination.

Science.gov (United States)

Baaten, Gijs G; Sonder, Gerard J B; Van Der Loeff, Maarten F Schim; Coutinho, Roel A; Van Den Hoek, Anneke

2010-01-01

To evaluate whether changes in attack rates of fecal-orally transmitted diseases among travelers are related to changes in pretravel vaccination practices or better hygienic standards at travel destination. National surveillance data on all laboratory-confirmed cases of travel-related hepatitis A, shigellosis, and typhoid fever diagnosed in the Netherlands from 1995 to 2006 were matched with the number of Dutch travelers to developing countries to calculate region-specific annual attack rates. Trends in attack rates of non-vaccine-preventable shigellosis were compared with those of vaccine-preventable hepatitis A and typhoid fever. Trends were also compared with three markers for hygienic standards of the local population at travel destinations, drawn from the United Nations Development Programme database: the human development index, the sanitation index, and the water source index. Attack rates among Dutch travelers to developing regions declined for hepatitis A, shigellosis, and typhoid fever. Region-specific trends in attack rates of shigellosis resembled trends of hepatitis A and typhoid fever. Declining attack rates of the three fecal-orally transmitted diseases correlated with improvements in socioeconomic, sanitary, and water supply conditions of the local population at travel destination. These findings suggest that improved hygienic standards at travel destination strongly contributed to the overall decline in attack rates of fecal-orally transmitted diseases among visiting travelers. © 2010 International Society of Travel Medicine.

41 CFR 301-75.204 - May we use Government contractor-issued travelers checks to pay for the interviewee's travel...

Science.gov (United States)

2010-07-01

... contractor-issued travelers checks to pay for the interviewee's travel expenses? 301-75.204 Section 301-75.204 Public Contracts and Property Management Federal Travel Regulation System TEMPORARY DUTY (TDY) TRAVEL ALLOWANCES AGENCY RESPONSIBILITIES 75-PRE-EMPLOYMENT INTERVIEW TRAVEL Obtaining Travel Services...

Travel-related acquisition of diarrhoeagenic bacteria, enteral viruses and parasites in a prospective cohort of 98 Dutch travellers.

Science.gov (United States)

van Hattem, Jarne M; Arcilla, Maris S; Grobusch, Martin P; Bart, Aldert; Bootsma, Martin C; van Genderen, Perry J; van Gool, Tom; Goorhuis, Abraham; van Hellemond, Jaap J; Molenkamp, Richard; Molhoek, Nicky; Oude Lashof, Astrid M; Stobberingh, Ellen E; de Wever, Bob; Verbrugh, Henri A; Melles, Damian C; Penders, John; Schultsz, Constance; de Jong, Menno D

2017-09-01

Limited prospective data are available on the acquisition of viral, bacterial and parasitic diarrhoeagenic agents by healthy individuals during travel. To determine the frequency of travel associated acquisition of 19 pathogens in 98 intercontinental travellers, qPCR was used to detect 8 viral pathogens, 6 bacterial enteric pathogens and 5 parasite species in faecal samples collected immediately before and after travel. We found high pre-travel carriage rates of Blastocystis spp. and Dientamoeba fragilis of 32% and 19% respectively. Pre-travel prevalences of all other tested pathogens were below 3%. Blastocystis spp. (10%), Plesiomonas shigelloides (7%), D. fragilis (6%) and Shigella spp. (5%) were the most frequently acquired pathogens and acquisition of enteral viruses and hepatitis E virus in this relatively small group of travellers was rare or non-existent. Our findings suggest that the role of viruses as the cause of persisting traveller's diarrhoea is limited and bacterial pathogens are more likely as a cause of traveller's diarrhoea. The substantial proportion of travellers carrying Blastocystis spp. and D. fragilis before travel warrants cautious interpretation of positive samples in returning travellers with gastrointestinal complaints. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Development of Independent Travel in China in the Future and Travel Agents’ Coping Strategies

OpenAIRE

Pan, Yulu

2010-01-01

Abstract The purpose of this research is to understand the general trend of independent travel in China from tourists’ perspectives and what strategies travel agents should adopt to cope with the increased independent travel. This project is based on both primary research and secondary research. Quantitative and qualitative data are collected and analyzed for deeply exploration about independent travel in order to understand tourists’ attitudes, expectations and perspectives. By this w...

On the dynamics of large-scale traveling ionospheric disturbances over Europe on 20 November 2003

Czech Academy of Sciences Publication Activity Database

Borries, C.; Jakowski, N.; Kauristie, K.; Amm, O.; Mielich, J.; Kouba, Daniel

2017-01-01

Roč. 122, č. 1 (2017), s. 1199-1211 ISSN 2169-9380 R&D Projects: GA ČR(CZ) GA15-24688S Institutional support: RVO:68378289 Keywords : heating * ionosphere * storm * TEC * TID Subject RIV: DG - Athmosphere Sciences, Meteorology OBOR OECD: Meteorology and atmospheric sciences Impact factor: 2.733, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/2016JA023050/epdf

Safe travels? HIV transmission among Britons travelling abroad.

Science.gov (United States)

Rice, B; Gilbart, V L; Lawrence, J; Smith, R; Kall, M; Delpech, V

2012-05-01

The aim of the study was to identify and describe the characteristics of persons born in the UK who acquire HIV infection abroad. Analyses using case reports and follow-up data from the national HIV database held at the Health Protection Agency were performed. Fifteen per cent (2066 of 13 891) of UK-born adults diagnosed in England, Wales and Northern Ireland between 2002 and 2010 acquired HIV infection abroad. Thailand (534), the USA (117) and South Africa (108) were the countries most commonly reported. As compared with UK-born adults acquiring HIV infection in the UK, those acquiring HIV infection abroad were significantly (P sex with a commercial sex worker (5.6% vs. 1%, respectively). Among men infected in Thailand, 11% reported sex with a commercial sex worker. A substantial number of UK-born adults are acquiring HIV infection in countries with generalized HIV epidemics, and in common holiday destinations. Of particular concern is the high proportion of men infected reporting sex with a commercial sex worker. We recommend HIV prevention and testing efforts be extended to include travellers abroad, and that sexual health advice be provided routinely in travel health consultations and in occupational health travel advice packs, particularly to those travelling to high HIV prevalence areas and destinations for sex tourism. Safer sex messages should include an awareness of the potential detrimental health and social impacts of the sex industry. © 2012 British HIV Association.

Pre-travel advice at a crossroad: Medical preparedness of travellers to South and Southeast-Asia - The Hamburg Airport Survey.

Science.gov (United States)

Rolling, Thierry; Mühlenpfordt, Melina; Addo, Marylyn M; Cramer, Jakob P; Vinnemeier, Christof D

Specific travel-related recommendations exist for the prevention or self-treatment of infectious diseases contracted by travellers to the tropics. In the current study, we assessed the medical preparedness per these recommendations, focusing on whether travellers carried antidiarrheal and antimalarial medication with them stratified by type of pre-travel advice. We surveyed travellers departing from Hamburg International Airport to South or Southeast Asia, using a questionnaire on demographic, medical and travel characteristics. 975 travellers were analysed - the majority (817, 83%) being tourists. A large proportion packed any antidiarrheal medication (612, 63%) - most frequently loperamide (440, 72%). Only 176 of 928 (19%) travellers to destinations with low-to medium risk for malaria packed a recommended antimalarial medication. The majority (162, 17%) of them carried antimalarials as stand-by emergency treatment (SBET). 468 (48%) travellers had a pre-travel medical consultation. This lead to higher odds of carrying SBET- with the highest odds associated with a consultation at a travel medicine specialist (OR 7.83 compared to no consultation). Attending a travel medicine specialist was associated with better adherence to current recommendations concerning the carriage of stand-by emergency treatment of malaria. However, the proportion of travellers seeking pre-travel health advice was overall low in our population. Promoting pre-travel consultations may, therefore, lead to higher adherence to the current recommendations in travel medicine. Copyright © 2017 Elsevier Ltd. All rights reserved.

Disturbance rejection performance analyses of closed loop control systems by reference to disturbance ratio.

Science.gov (United States)

Alagoz, Baris Baykant; Deniz, Furkan Nur; Keles, Cemal; Tan, Nusret

2015-03-01

This study investigates disturbance rejection capacity of closed loop control systems by means of reference to disturbance ratio (RDR). The RDR analysis calculates the ratio of reference signal energy to disturbance signal energy at the system output and provides a quantitative evaluation of disturbance rejection performance of control systems on the bases of communication channel limitations. Essentially, RDR provides a straightforward analytical method for the comparison and improvement of implicit disturbance rejection capacity of closed loop control systems. Theoretical analyses demonstrate us that RDR of the negative feedback closed loop control systems are determined by energy spectral density of controller transfer function. In this manner, authors derived design criteria for specifications of disturbance rejection performances of PID and fractional order PID (FOPID) controller structures. RDR spectra are calculated for investigation of frequency dependence of disturbance rejection capacity and spectral RDR analyses are carried out for PID and FOPID controllers. For the validation of theoretical results, simulation examples are presented. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Common Health Risks, Required Precautions of Travelers and their Customs Towards the Use of Travel Medicine Services.

Science.gov (United States)

Roupa, Zoe; Zikos, Dimitrios; Vasilopoulos, Aristides; Diomidous, Marianna

2012-01-01

There is an increasing number of people who travel around the world. Every traveler is exposed to nearly all infectious risks which may occur during his travel time. Some of the main risk factors can be water quality, temperature and high humidity and the exposure to multi-resistant microorganisms. To tackle the upcoming problem there is an imperative need to develop a new branch of medicine with the name of travel medicine. A consultation prior to departure for an upcoming trip is required, focusing to a personalized healthcare plan, based on international scientific protocols and epidemiological studies.Travelers must acquire essential information about the prevailing hygiene conditions and climatic differentiations that occur in the region. Additionally there are several health risks upon the arrival at destination. A scheduled visit to a health professional is necessary, especially in the case of travelers suffering from chronic diseases or those taking medication, while vaccination is considered essential for specific destination countries. Healthcare professionals should be able to inform travelers and evaluate their needs. According to research studies on notion and attitudes travelers' specific risks, only few of them are well-informed during a trip. While most studies indicate that travelers have some kind of pre travel medical consultation, not all of them proceed to the required vaccinations and medications. Travelling for business or leisure around the world may be unhealthy. The importance of proper preparation prior to the travel requires to be adequately informed by specialized healthcare professionals, and to receive appropriate vaccinations and medications, when required. The results of the review of notions and attitudes of travelers during the trip indicate not only the need for further development of the branch of travel medicine but especially the need for the expansion and the availability of health services.

International travel in the immunocompromised patient: a cross-sectional survey of travel advice in 254 consecutive patients.

Science.gov (United States)

Bialy, C; Horne, K; Dendle, C; Kanellis, J; Littlejohn, G; Ratnam, I; Woolley, I

2015-06-01

Our primary aim was to determine the rate of overseas travel in immunocompromised individuals attending appropriate clinics at an Australian tertiary care hospital. We also aimed to characterise health-seeking behaviour prior to travel and investigated sources of pre-travel advice, compared travel patterns and activities between three specific immunosuppressed groups, and examined pre-immunosuppression patient serology. We implemented a cross-sectional survey of patients between February and August 2012. This survey was implemented among three outpatient populations at Monash Medical Centre, an Australian tertiary care hospital. We recruited 254 immunosuppressed adults from three patient populations: human immunodeficiency virus-positive individuals, renal transplant patients and rheumatology patients requiring immunosuppressive therapy. No clinical intervention was performed. In the 10 years preceding the survey, 153 (60.2%) participants reported international travel. Of these, 105 (68.6%) were immunosuppressed at the time of travel. These patients were 47.6% male and 60% Australian born. Forty per cent were visiting friends and relatives as part of their travel. Fifty-four per cent of those immunocompromised at the time of travel were going to high-risk destinations. Pathology files indicated that serological screening was frequently not performed prior to immunosuppression in the renal transplant and rheumatology groups. Immunocompromised patients often travel to high-risk destinations with limited or inadequate pre-travel preparations. Doctors caring for the immunocompromised should be aware of travel risks, suitable vaccination protocols and when to refer to specialist travel clinics. © 2015 Royal Australasian College of Physicians.

Season and weather effects on travel-related mood and travel satisfaction

NARCIS (Netherlands)

Ettema, Dick; Friman, Margareta; Olsson, Lars E.; Gärling, Tommy

2017-01-01

This study examines the effects of season and weather on mood (valence and activation) and travel satisfaction (measured by the Satisfaction with Travel Scale). Analyses are presented of 562 time-sampled morning commutes to work made by 363 randomly sampled people in three different Swedish cities

Pre-travel advice concerning vector-borne diseases received by travelers prior to visiting Cuzco, Peru.

Science.gov (United States)

Mejia, Christian R; Centeno, Emperatriz; Cruz, Briggitte; Cvetkovic-Vega, Aleksandar; Delgado, Edison; Rodriguez-Morales, Alfonso J

2016-01-01

Peru is an increasingly popular tourist destination that poses a risk to travelers due to endemic vector-borne diseases (VBDs). The objective of our study was to determine which factors are associated with receiving pre-travel advice (PTA) for VBDs among travelers visiting Cuzco, Peru. A cross-sectional secondary analysis based on data from a survey among travelers departing Cuzco at Alejandro Velazco Astete International Airport during the period January-March 2012 was conducted. From the 1819 travelers included in the original study, 1717 were included in secondary data analysis. Of these participants, 42.2% received PTA and 2.9% were informed about vector-borne diseases, including yellow fever (1.8%), malaria (1.6%) and dengue fever (0.1%). Receiving information on VBDs was associated with visiting areas endemic to yellow fever and dengue fever in Peru. The only disease travelers received specific recommendations for before visiting an endemic area for was yellow fever. Only 1 in 30 tourists received information on VBD prevention; few of those who traveled to an endemic area were warned about specific risks for infectious diseases prior to their trip. These important findings show that most tourists who travel to Peru do not receive PTA for the prevention of infectious and VBD, which can affect not only the travelers but their countries of origin as well. Copyright © 2015 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved.

Immunocompromised Travelers: Demographic Characteristics, Travel Destinations, and Pretravel Health Care from the U.S. Global TravEpiNet Consortium.

Science.gov (United States)

Schwartz, Brian S; Rosen, Jessica; Han, Pauline V; Hynes, Noreen A; Hagmann, Stefan H; Rao, Sowmya R; Jentes, Emily S; Ryan, Edward T; LaRocque, Regina C

2015-11-01

An increasing number of immunocompromised individuals are pursuing international travel, and a better understanding of their international travel patterns and pretravel health care is needed. We evaluated the clinical features, itineraries, and pretravel health care of 486 immunocompromised international travelers seen at Global TravEpiNet sites from January 2009 to June 2012. We used bivariate analyses and logistic regressions using random intercept models to compare demographic and travel characteristics, vaccines administered, and medications prescribed for immunocompromised travelers versus 30,702 immunocompetent travelers. Immunocompromised travelers pursued itineraries that were largely similar to those of immunocompetent travelers, with nearly one-third of such travelers visiting countries with low human development indices. Biological agents, including tumor necrosis factor blockers, were commonly used immunosuppressive medications among immunocompromised travelers. A strong collaboration between travel-medicine specialists, primary care doctors, and specialist physicians is needed to prepare immunocompromised people for international travel. Incorporating routine questioning and planning regarding travel into the primary care visits of immunocompromised people may be useful. © The American Society of Tropical Medicine and Hygiene.

Network structure and travel time perception.

Science.gov (United States)

Parthasarathi, Pavithra; Levinson, David; Hochmair, Hartwig

2013-01-01

The purpose of this research is to test the systematic variation in the perception of travel time among travelers and relate the variation to the underlying street network structure. Travel survey data from the Twin Cities metropolitan area (which includes the cities of Minneapolis and St. Paul) is used for the analysis. Travelers are classified into two groups based on the ratio of perceived and estimated commute travel time. The measures of network structure are estimated using the street network along the identified commute route. T-test comparisons are conducted to identify statistically significant differences in estimated network measures between the two traveler groups. The combined effect of these estimated network measures on travel time is then analyzed using regression models. The results from the t-test and regression analyses confirm the influence of the underlying network structure on the perception of travel time.

Travels in Architectural History

Directory of Open Access Journals (Sweden)

Davide Deriu

2016-11-01

Full Text Available Travel is a powerful force in shaping the perception of the modern world and plays an ever-growing role within architectural and urban cultures. Inextricably linked to political and ideological issues, travel redefines places and landscapes through new transport infrastructures and buildings. Architecture, in turn, is reconstructed through visual and textual narratives produced by scores of modern travellers — including writers and artists along with architects themselves. In the age of the camera, travel is bound up with new kinds of imaginaries; private records and recollections often mingle with official, stereotyped views, as the value of architectural heritage increasingly rests on the mechanical reproduction of its images. Whilst students often learn about architectural history through image collections, the place of the journey in the formation of the architect itself shifts. No longer a lone and passionate antiquarian or an itinerant designer, the modern architect eagerly hops on buses, trains, and planes in pursuit of personal as well as professional interests. Increasingly built on a presumption of mobility, architectural culture integrates travel into cultural debates and design experiments. By addressing such issues from a variety of perspectives, this collection, a special 'Architectural Histories' issue on travel, prompts us to rethink the mobile conditions in which architecture has historically been produced and received.

Prevention of influenza among travellers attending at a UK travel clinic: beliefs and perceptions. A cross-sectional study.

Science.gov (United States)

Masuet-Aumatell, Cristina; Toovey, Stephen; Zuckerman, Jane N

2013-07-01

Travellers' compliance with measures to prevent influenza through the use of antivirals and influenza vaccine remains very poor despite influenza being one of the commonest travel and vaccine-preventable diseases. A study was undertaken to assess travellers' beliefs, perceptions and intentions to take antivirals for the treatment and prevention of influenza during the H1N1 pandemic. A cross-sectional survey (n = 96) of travellers who attended the Royal Free Travel Health Centre, London, UK was undertaken in September 2009. A self-administered questionnaire was completed by a traveller in advance of their pre-travel health consultation. Logistic regression identified variables independently associated with compliance. Influenza vaccination uptake for the 5 years preceding the study was found to be 20·8%. This was statistically significantly higher for older travellers and those with underlying health conditions (P study identifies some beliefs and perceptions travellers consider with regard to the therapeutic and preventive influenza use of antivirals during the H1N1 pandemic; it underscores the importance of travellers receiving hemisphere appropriate influenza vaccination. The external validity of these study findings requires further corroboration involving other travel clinics and different cohorts of travellers during seasonal activity or outbreaks of influenza. These findings could guide the development of future strategies for the prevention of influenza in travellers. © 2012 John Wiley & Sons Ltd.

Carbon recovery dynamics following disturbance by selective logging in Amazonian forests

Science.gov (United States)

Piponiot, Camille; Sist, Plinio; Mazzei, Lucas; Peña-Claros, Marielos; Putz, Francis E; Rutishauser, Ervan; Shenkin, Alexander; Ascarrunz, Nataly; de Azevedo, Celso P; Baraloto, Christopher; França, Mabiane; Guedes, Marcelino; Honorio Coronado, Eurídice N; d'Oliveira, Marcus VN; Ruschel, Ademir R; da Silva, Kátia E; Doff Sotta, Eleneide; de Souza, Cintia R; Vidal, Edson; West, Thales AP; Hérault, Bruno

2016-01-01

When 2 Mha of Amazonian forests are disturbed by selective logging each year, more than 90 Tg of carbon (C) is emitted to the atmosphere. Emissions are then counterbalanced by forest regrowth. With an original modelling approach, calibrated on a network of 133 permanent forest plots (175 ha total) across Amazonia, we link regional differences in climate, soil and initial biomass with survivors’ and recruits’ C fluxes to provide Amazon-wide predictions of post-logging C recovery. We show that net aboveground C recovery over 10 years is higher in the Guiana Shield and in the west (21 ±3 Mg C ha-1) than in the south (12 ±3 Mg C ha-1) where environmental stress is high (low rainfall, high seasonality). We highlight the key role of survivors in the forest regrowth and elaborate a comprehensive map of post-disturbance C recovery potential in Amazonia. DOI: http://dx.doi.org/10.7554/eLife.21394.001 PMID:27993185

Morbidity among Israeli paediatric travellers.

Science.gov (United States)

Rabinowicz, Shira; Schwartz, Eli

2017-09-01

International travel, particularly to developing countries, is becoming increasingly common among the Israeli population, including an increase in the number of travelling children. Since children are a distinct travellers' population, data about their post-travel morbidity are needed. A retrospective study which examined all children (0-19 years old) who presented to our centre after international travel from 1999 to 2015. About 314 children were seen. The mean age was 10 years (SD ± 5.8). Most of the patients (80.6%) were tourists, and the rest were expatriates. The main destinations visited were South-Asia (46.5%), Sub-Saharan Africa (33.4%), Latin-America (7%) and Europe (6.4%). Overall, the most common diagnoses were gastrointestinal (GI) (mainly chronic) disorders (30.6%), followed by febrile diseases (26.4%), among which 18.1% of patients were diagnosed with dengue fever and 12% with malaria. Dermatologic conditions accounted for 25.2%. Additional diagnoses were schistosomiasis (6.4%) and neuropsychiatric symptoms (2.2%). A substantial part, 10.8%, had eosinophilia, either symptomatic or asymptomatic. Travellers to Asia, compared to travellers to Africa, presented more commonly with GI illness (OR 2.02, 95% confidence interval 1.13-3.61), and dermatologic conditions (OR 1.94, 95% confidence interval 1.05-3.61). Morbidity was associated with a variety of transmission modes, such as food-borne illnesses (30.9%), bite and sting wounds (10.2%), mosquito-borne infections (8%), freshwater contact (6.7%) and tick-borne infections (2.2%). The main conditions seen in paediatric returning travellers were GI, febrile and dermatologic illnesses, some may be rare in their country of origin. Targeting care for the suspected pathogens based on updated knowledge of epidemiology and thorough travel history is essential. © International Society of Travel Medicine, 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com

Travel mode choice and travel satisfaction : bridging the gap between decision utility and experienced utility

OpenAIRE

De Vos, Jonas; Mokhtarian, Patricia L; Schwanen, Tim; Van Acker, Veronique; Witlox, Frank

2016-01-01

Over the past decades research on travel mode choice has evolved from work that is informed by utility theory, examining the effects of objective determinants, to studies incorporating more subjective variables such as habits and attitudes. Recently, the way people perceive their travel has been analyzed with transportation-oriented scales of subjective wellbeing, and particularly the satisfaction with travel scale. However, studies analyzing the link between travel mode choice (i.e., decisio...

Reduction of travellers' diarrhoea by WC/rBS oral cholera vaccine in young, high-risk travellers.

Science.gov (United States)

Torrell, Josep Ma Ramon; Aumatell, Cristina Masuet; Ramos, Sergi Morchon; Mestre, Laura Gavaldà; Salas, Carme Micheo

2009-06-19

A bidirectional cohort study investigates whether pre-travel vaccination with whole cell/recombinant B subunit inactivated, killed oral cholera vaccine reduces the incidence of diarrhoea in young adult travellers to high-risk areas. Risk of travellers' diarrhoea was assessed according to destination and reason for travel in high-risk travellers of a travel clinic in Barcelona, Spain. Those at high-risk between January and December 2005 were advised on water/food safety and hygiene. High-risk travellers between January and December 2006 were additionally vaccinated with WC/rBS oral cholera vaccine. Data regarding diarrhoea were gathered by structured telephone interview or e-mailed questionnaire following the travellers' return. The incidence of diarrhoea in the group vaccinated with WC/rBS oral cholera vaccine (n=321) was 17.4%, compared with 39.7% in the non-vaccinated group (n=337) (adjusted risk ratio 0.40). The first episode was significantly shorter in the vaccinated group (mean 2.3 days) than in the non-vaccinated group (mean 3.8 days) (pyoung, high-risk travellers. Vaccination with the WC/rBS oral cholera vaccine as well as food safety and hygiene advice could offer effective means of reducing the risk of diarrhoea while abroad.

U.S. regional greenhouse gas emissions analysis comparing highly resolved vehicle miles traveled and CO2 emissions: mitigation implications and their effect on atmospheric measurements

Science.gov (United States)

Mendoza, D. L.; Gurney, K. R.

2010-12-01

Carbon dioxide (CO2) is the most abundant anthropogenic greenhouse gas and projections of fossil fuel energy demand show CO2 concentrations increasing indefinitely into the future. After electricity production, the transportation sector is the second largest CO2 emitting economic sector in the United States, accounting for 32.3% of the total U.S. emissions in 2002. Over 80% of the transport sector is composed of onroad emissions, with the remainder shared by the nonroad, aircraft, railroad, and commercial marine vessel transportation. In order to construct effective mitigation policy for the onroad transportation sector and more accurately predict CO2 emissions for use in transport models and atmospheric measurements, analysis must incorporate the three components that determine the CO2 onroad transport emissions: vehicle fleet composition, average speed of travel, and emissions regulation strategies. Studies to date, however, have either focused on one of these three components, have been only completed at the national scale, or have not explicitly represented CO2 emissions instead relying on the use of vehicle miles traveled (VMT) as an emissions proxy. National-level projections of VMT growth is not sufficient to highlight regional differences in CO2 emissions growth due to the heterogeneity of vehicle fleet and each state’s road network which determines the speed of travel of vehicles. We examine how an analysis based on direct CO2 emissions and an analysis based on VMT differ in terms of their emissions and mitigation implications highlighting potential biases introduced by the VMT-based approach. This analysis is performed at the US state level and results are disaggregated by road and vehicle classification. We utilize the results of the Vulcan fossil fuel CO2 emissions inventory which quantified emissions for the year 2002 across all economic sectors in the US at high resolution. We perform this comparison by fuel type,12 road types, and 12 vehicle types

Disturbance recording system

International Nuclear Information System (INIS)

Chandra, A.K.; Deshpande, S.V.; Mayya, A.; Vaidya, U.W.; Premraj, M.K.; Patil, N.B.

1994-01-01

A computerized system for disturbance monitoring, recording and display has been developed for use in nuclear power plants and is versatile enough to be used where ever a large number of parameters need to be recorded, e.g. conventional power plants, chemical industry etc. The Disturbance Recording System (DRS) has been designed to continuously monitor a process plant and record crucial parameters. The DRS provides a centralized facility to monitor and continuously record 64 process parameters scanned every 1 sec for 5 days. The system also provides facility for storage of 64 parameters scanned every 200 msec during 2 minutes prior to and 3 minutes after a disturbance. In addition the system can initiate, on demand, the recording of 8 parameters at a fast rate of every 5 msec for a period of 5 sec. and thus act as a visicorder. All this data is recorded in non-volatile memory and can be displayed, printed/plotted and used for subsequent analysis. Since data can be stored densely on floppy disks, the volume of space required for archival storage is also low. As a disturbance recorder, the DRS allows the operator to view the state of the plant prior to occurrence of the disturbance and helps in identifying the root cause. (author). 10 refs., 7 figs

Travel/Travelers and Parasitic Diseases

Science.gov (United States)

... of the world and specific country. Many infectious diseases transmitted in food and water can also be acquired directly through the fecal-oral route. Parasitic Illnesses That Can Be Acquired During Travel* From Contaminated Food and Water More ... filariasis African sleeping sickness Onchoceriasis *This list ...

Calculation of groundwater travel time

International Nuclear Information System (INIS)

Arnett, R.C.; Sagar, B.; Baca, R.G.

1984-12-01

Pre-waste-emplacement groundwater travel time is one indicator of the isolation capability of the geologic system surrounding a repository. Two distinct modeling approaches exist for prediction of groundwater flow paths and travel times from the repository location to the designated accessible environment boundary. These two approaches are: (1) the deterministic approach which calculates a single value prediction of groundwater travel time based on average values for input parameters and (2) the stochastic approach which yields a distribution of possible groundwater travel times as a function of the nature and magnitude of uncertainties in the model inputs. The purposes of this report are to (1) document the theoretical (i.e., mathematical) basis used to calculate groundwater pathlines and travel times in a basalt system, (2) outline limitations and ranges of applicability of the deterministic modeling approach, and (3) explain the motivation for the use of the stochastic modeling approach currently being used to predict groundwater pathlines and travel times for the Hanford Site. Example calculations of groundwater travel times are presented to highlight and compare the differences between the deterministic and stochastic modeling approaches. 28 refs

Future Trends in Business Travel Decision Making

Science.gov (United States)

Mason, Keith J.

2002-01-01

This research surveys twenty large companies and their travellers to identify and evaluate the effects of pressures on the business travel market in the future. The influence of the following areas on the decision making process are addressed: (1) Corporate travel policies and increasing professionalism in corporate purchasing; (2) The development of global strategic airline alliances; (3) The emergence of low cost airlines on short haul markets; and (4) The development of internet based booking tools and travel agency IT. The survey shows differences in views between travel managers, and travellers with regard to corporate travel policies. While travel managers see policy rules, travellers interpret these as guidelines, indicating travel managers will need to take further actions to exercise true control of travel budgets. The data shows that companies are more likely to prescribe a class of airline ticket, than the choice of airline itself. Corporate hierarchical bias in travel policies is still common both for short and particularly long haul flying. Other findings show that while travel managers believe that their companies are likely to sign global deals with strategic airline groups within a five year period in a bid to consolidating spending, they also believe that nearly a third of short haul flying will be taken with low cost carriers, indicating further penetration in this business travel market by these carriers. The paper also provides other predictions about the business travel market, based on the survey findings.

Travelers' Health: Water Disinfection for Travelers

Science.gov (United States)

... Safety Road Safety - 8 Steps MERS Health Advisory poster MERS Pictogram CDC Guide for Healthy Travel Website ... compressed carbon, or large-pore hollow-fiber filter elements are sufficient to remove bacteria and protozoan cysts ...

Integrating Remote Sensing, Field Observations, and Models to Understand Disturbance and Climate Effects on the Carbon Balance of the West Coast U.S., Final Report

Energy Technology Data Exchange (ETDEWEB)

Beverly E. Law

2011-10-05

As an element of NACP research, the proposed investigation is a two pronged approach that derives and evaluates a regional carbon (C) budget for Oregon, Washington, and California. Objectives are (1) Use multiple data sources, including AmeriFlux data, inventories, and multispectral remote sensing data to investigate trends in carbon storage and exchanges of CO2 and water with variation in climate and disturbance history; (2) Develop and apply regional modeling that relies on these multiple data sources to reduce uncertainty in spatial estimates of carbon storage and NEP, and relative contributions of terrestrial ecosystems and anthropogenic emissions to atmospheric CO2 in the region; (3) Model terrestrial carbon processes across the region, using the Biome-BGC terrestrial ecosystem model, and an atmospheric inverse modeling approach to estimate variation in rate and timing of terrestrial uptake and feedbacks to the atmosphere in response to climate and disturbance.

75 FR 24434 - Federal Travel Regulation (FTR); Transportation in Conjunction With Official Travel and Relocation

Science.gov (United States)

2010-05-05

...-0010, sequence 1] RIN 3090-AJ02 Federal Travel Regulation (FTR); Transportation in Conjunction With Official Travel and Relocation AGENCY: Office of Governmentwide Policy, General Services Administration (GSA). ACTION: Final rule. SUMMARY: This final rule amends the Federal Travel Regulation (FTR), by...

A process model of voluntary travel behavior modification and effects of Travel Feedback Programs (TFPs)

OpenAIRE

Taniguchi, Ayako

2007-01-01

This study tested an integrated process model of travel behavior modification. We used a model that combined the theory of planned behavior (TPB), norm activation theory (NAT), a theory of implementation intention, and theories of habit. To test the integrated model, we used panel data (n = 208) obtained before and after travel feedback programs (TFPs); the TFP is a communication program aimed at voluntary travel behavior modification, from automobile use to non-auto means of travel such as p...

Modeling the Propagation of Atmospheric Gravity Waves Produced by an Underground Nuclear Explosion using the Transfer Function Model

Science.gov (United States)

Bruntz, R. J.; Mayr, H. G.; Paxton, L. J.

2017-12-01

We will present results from the Transfer Function Model (TFM), which simulates the neutral atmosphere, from 0 to 700 km, across the entire globe (pole to pole). The TFM is able to rapidly calculate the density and temperature perturbations created by a localized impulse. We have used TFM to simulate a ground-level explosion (equivalent to an underground nuclear explosion (UNE)) and its effects on the neutral atmosphere, including the propagation of gravity waves up to ionospheric heights. At ionospheric altitudes ion-neutral interactions are expected to lead to perturbations in the electron density. These perturbations can be observed as changes in the total electron content (TEC), a feature readily observed by the globally distributed network of global navigation satellite systems (GNSS) sensors. We will discuss the time and location of the maximum atmospheric disturbances at a number of altitudes, including the peaks of several ionospheric layers, including the F2 layer, which is often treated as the major driver of changes in GNSS-TEC observations. We will also examine the drop-off of atmospheric disturbances at those altitudes, both with increasing time and distance. The 6 known underground nuclear explosions (UNEs) by North Korea in the 21st century have sparked increased interest in UNE detection through atmospheric and ionospheric observations. The latest test by North Korea (3 Sept. 2017) was the largest UNE in over 2 decades. We will compare TFM results to the analysis of previous UNEs, including some tests by North Korea, and discuss possible confounding factors in predicting the time, location, and amplitude of atmospheric and ionospheric disturbances produced by a UNE.

End to End Travel

Data.gov (United States)

US Agency for International Development — E2 Solutions is a web based end-to-end travel management tool that includes paperless travel authorization and voucher document submissions, document approval...

Acoustic Travel Time and Hydrostatic Pressure in Sermilik Fjord in Southeastern Greenland from 2011-08-23 to 2016-08-11 (NCEI Accession 0163212)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — These data records are time series of (1) round trip surface to bottom acoustic travel time, (2) bottom pressure and (3) bottom temperature (with the latter internal...

Valuation of travel time savings for intercity travel: The Madrid-Barcelona corridor

DEFF Research Database (Denmark)

Roman, Concepcion; Carlos Martin, Juan; Espino, Raquel

2014-01-01

We derive values of travel time savings (VOT) for the Madrid-Barcelona corridor, linking the two largest cities in Spain, based on the estimation of discrete choice models among the main public transport services in the corridor: air transport, high speed rail (HSR) and bus. The new HSR alternative...... (which started to operate in February 2008) competes directly with one of the densest airline domestic markets in the world, and its introduction produced substantial improvements in level of service, achieving reductions in travel time of more than 50% over the conventional train. A specifically...... to provide useful information to quantify users' benefits during the lifespan of a given project. We found, as expected, that HSR and air transport users exhibit substantially higher values for saving travel time than bus travellers. Also as expected, savings of waiting time are more valued than savings...

Intercity Travel Demand Analysis Model

Directory of Open Access Journals (Sweden)

Ming Lu

2014-01-01

Full Text Available It is well known that intercity travel is an important component of travel demand which belongs to short distance corridor travel. The conventional four-step method is no longer suitable for short distance corridor travel demand analysis for the time spent on urban traffic has a great impact on traveler's main mode choice. To solve this problem, the author studied the existing intercity travel demand analysis model, then improved it based on the study, and finally established a combined model of main mode choice and access mode choice. At last, an integrated multilevel nested logit model structure system was built. The model system includes trip generation, destination choice, and mode-route choice based on multinomial logit model, and it achieved linkage and feedback of each part through logsum variable. This model was applied in Shenzhen intercity railway passenger demand forecast in 2010 as a case study. As a result, the forecast results were consistent with the actuality. The model's correctness and feasibility were verified.

An Analysis of Cassini Observations Regarding the Structure of Jupiter's Equatorial Atmosphere

Science.gov (United States)

Choi, David S.; Simon-Miller, Amy A.

2012-01-01

A variety of intriguing atmospheric phenomena reside on both sides of Jupiter's equator. 5-micron bright hot spots and opaque plumes prominently exhibit dynamic behavior to the north, whereas compact, dark chevron-shaped features and isolated anticyclonic disturbances periodically occupy the southern equatorial latitudes. All of these phenomena are associated with the vertical and meridional perturbations of Rossby waves disturbing the mean atmospheric state. As previous observational analysis and numerical simulations have investigated the dynamics of the region, an examination of the atmosphere's vertical structure though radiative transfer analysis is necessary for improved understanding of this unique environment. Here we present preliminary analysis of a multispectral Cassini imaging data set acquired during the spacecraft's flyby of Jupiter in 2000. We evaluated multiple methane and continuum spectral channels at available viewing angles to improve constraints on the vertical structure of the haze and cloud layers comprising these interesting features. Our preliminary results indicate distinct differences in the structure for both hemispheres. Upper troposphere hazes and cloud layers are prevalent in the northern equatorial latitudes, but are not present in corresponding southern latitudes. Continued analysis will further constrain the precise structure present in these phenomena and the differences between them.

Defining Disturbance for Microbial Ecology.

Science.gov (United States)

Plante, Craig J

2017-08-01

Disturbance can profoundly modify the structure of natural communities. However, microbial ecologists' concept of "disturbance" has often deviated from conventional practice. Definitions (or implicit usage) have frequently included climate change and other forms of chronic environmental stress, which contradict the macrobiologist's notion of disturbance as a discrete event that removes biomass. Physical constraints and disparate biological characteristics were compared to ask whether disturbances fundamentally differ in microbial and macroorganismal communities. A definition of "disturbance" for microbial ecologists is proposed that distinguishes from "stress" and other competing terms, and that is in accord with definitions accepted by plant and animal ecologists.

FORMS OF YOUTH TRAVEL

OpenAIRE

Moisã Claudia Olimpia; Moisã Claudia Olimpia

2011-01-01

Taking into account the suite of motivation that youth has when practicing tourism, it can be said that the youth travel takes highly diverse forms. These forms are educational tourism, volunteer programs and “work and travel”, cultural exchanges or sports tourism and adventure travel. In this article, we identified and analyzed in detail the main forms of youth travel both internationally and in Romania. We also illustrated for each form of tourism the specific tourism products targeting you...

Travel and transport

DEFF Research Database (Denmark)

Bill, Jan; Roesdahl, Else

2007-01-01

On the interrelationship between travel, transport and society; on land transport, sea and river transport, and on winter transport;  on the related technologies and their developments......On the interrelationship between travel, transport and society; on land transport, sea and river transport, and on winter transport;  on the related technologies and their developments...

41 CFR 301-70.904 - Must travelers whom we carry on Government aircraft be authorized to travel?

Science.gov (United States)

2010-07-01

... flight in which they are also traveling (i.e., being transported from point to point) are considered... carry on Government aircraft be authorized to travel? 301-70.904 Section 301-70.904 Public Contracts and Property Management Federal Travel Regulation System TEMPORARY DUTY (TDY) TRAVEL ALLOWANCES AGENCY...

Travelers' diarrhea.

Science.gov (United States)

Barrett-Connor, E

1973-03-01

On the average, one-fourth of North Americans visiting developing countries experience a self-limited diarrheal illness that interferes with holiday or business activities. Recent work suggests that these episodes are caused by a small inoculum of enteropathogenic Escherichia coli which are common in the country visited and rare in the country of origin. Neither antimicrobial treatment nor anti-diarrheal agents have proven benefit once the illness has begun. Despite its frequent use, iodochlorhydroxyquin has not been shown in double blind studies to be effective as a preventive agent, and may be dangerous. The status of furazolidone for prevention of tourist diarrhea is questionable. Both neomycin sulfate and phythalylsulfathiazole have demonstrated efficacy as chemoprophylactics in Mexico. However, their use should be restricted to limited types of travel and travelers. General admonitions concerning avoidance of certain ingestibles are recommended; despite questionable value in preventing travelers' diarrhea such precautions may prevent more serious gastrointestinal illness.

8 CFR 1244.15 - Travel abroad.

Science.gov (United States)

2010-01-01

... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Travel abroad. 1244.15 Section 1244.15... REGULATIONS TEMPORARY PROTECTED STATUS FOR NATIONALS OF DESIGNATED STATES § 1244.15 Travel abroad. (a) After... Status shall not constitute permission to travel abroad. Permission to travel may be granted by the...

49 CFR 230.76 - Piston travel.

Science.gov (United States)

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Piston travel. 230.76 Section 230.76... Tenders Brake and Signal Equipment § 230.76 Piston travel. (a) Minimum piston travel. The minimum piston travel shall be sufficient to provide proper brake shoe clearance when the brakes are released. (b...

Atmospheric activity in red dwarf stars

International Nuclear Information System (INIS)

Pettersen, B.R.

1986-01-01

Active and inactive stars of similar mass and luminosity have similar physical conditions in their photospheres, outside of magnetically disturbed regions. Such field structures give rise to stellar activity, which manifests itself at all heights of the atmosphere. Observations of uneven distributions of flux across the stellar disc have led to the disovery of photospheric starspots, chromospheric plage areas, and coronal holes. Localized transient behavior has been identified in both thermal and non-thermal sources, such as flares, shock waves and particle acceleration. The common element to all active regions is the presence of strong magnetic field structures connecting the violently turbulent deep layers in the convection zones of stars with the tenuous outer atmospheres. Transport and dissipation of energy into the chromospheric and coronal regions are still much debated topics

Snow noise disturbance in Antarctic radio communications and development of mobile antenna for snow vehicle in Antarctica

Directory of Open Access Journals (Sweden)

Isao Fukushima

1997-07-01

Full Text Available Radio operators of the Japanese Antarctic Research Expedition (JARE have encountered critical radio noise disturbances caused by blizzards during oversnow travel. This noise appears to be caused by corona discharge at the edges of the vertical whip antenna. This paper describes several examples of snow noise experienced in Antarctica by JARE, the mechanism of generation of the noise, and a method of reducing the intensity of the noise. It also describes a High Effeciency Transmission Line Antenna which is small enough to mount on a snow vehicle and reduces the intensity of the snow noise.

8 CFR 244.15 - Travel abroad.

Science.gov (United States)

2010-01-01

... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Travel abroad. 244.15 Section 244.15 Aliens... NATIONALS OF DESIGNATED STATES § 244.15 Travel abroad. (a) After the grant of Temporary Protected Status... to travel abroad. Permission to travel may be granted by the director pursuant to the Service's...

Schistosomiasis in european travelers and migrants

DEFF Research Database (Denmark)

Lingscheid, Tilman; Kurth, Florian; Clerinx, Jan

2017-01-01

Schistosomiasis remains one of the most prevalent parasitic diseases worldwide and the infection is frequently found in travelers and migrants. The European Network for Tropical Medicine and Travel Health conducted a sentinel surveillance study on imported schistosomiasis between 1997 and 2010...... or antigen testing. Schistosomiasis remains a frequent infection in travelers and migrants to Europe. Travelers should be made aware of the risk of schistosomiasis infection when traveling to sub-Saharan Africa. Posttravel consultations particularly for returning expatriates are useful given the high...

Accurate estimation of indoor travel times

DEFF Research Database (Denmark)

Prentow, Thor Siiger; Blunck, Henrik; Stisen, Allan

2014-01-01

The ability to accurately estimate indoor travel times is crucial for enabling improvements within application areas such as indoor navigation, logistics for mobile workers, and facility management. In this paper, we study the challenges inherent in indoor travel time estimation, and we propose...... the InTraTime method for accurately estimating indoor travel times via mining of historical and real-time indoor position traces. The method learns during operation both travel routes, travel times and their respective likelihood---both for routes traveled as well as for sub-routes thereof. InTraTime...... allows to specify temporal and other query parameters, such as time-of-day, day-of-week or the identity of the traveling individual. As input the method is designed to take generic position traces and is thus interoperable with a variety of indoor positioning systems. The method's advantages include...

Pre-travel advice: an overview.

Science.gov (United States)

Sanford, Christopher

2002-12-01

The message of the pre-travel provider is necessarily paradoxic. First the provider lists a score of causes of illness and premature demise, and then states, "But it sounds like a great trip and I think you'll have fun." Pre-travel providers need to walk a fine line: they must encourage patients to be cautious but not paranoid, optimistic but realistic. This discussion is complicated further by the fact that risk reduction is not the only consideration; if it were, practitioners would advise patients to remain in the developed world and foray from their homes only to visit health clubs and the fruit-and-vegetable section of grocery stores. A tacit assumption in travel medicine is that some degree of acceptance of heightened risk is tolerated for the benefit of improved quality of life offered by travel abroad. The amount of risk that is reasonable to accept for a given benefit in quality of life yielded by travel cannot be quantified, however. Providers must render judgments on what is "reasonable" and what is not, and this complex decision is based on equal parts medical knowledge and intuition. At one extreme, mountaineers in Nepal have been found to have a 2.4% mortality rate per expedition [83,84]. The travel provider might make the reasonable decision to counsel these travelers to avoid that activity. These travelers most likely will ignore that advice, at which point the provider must endeavor to reduce risk to the extent possible. Other situations in which the provider should advise a change in itinerary or activities include counseling parents who plan to take an infant to high altitude or a pregnant woman who plans to scuba dive. If travelers remain cloistered in their hotel rooms, eating all meals from room service and watching CNN, then it could be suggested that they are overly risk-adverse and might consider foraying out of the hotel, despite the potential associated increased risks to health. Conversely, if travelers find themselves on motorcycles

CARLSON WAGONLIT TRAVEL

CERN Document Server

CARLSON WAGONLIT TRAVEL

2004-01-01

CARLSON WAGONLIT TRAVEL informs you that our agency will be closed from 17 December 2004 at 16:30 until 3 January 2005 at 8:30. For all URGENT MATTERS you can contact our CARLSON WAGONLIT TRAVEL branch at WHO (Mr Pierre Plumettaz), phone: 022 788 10 65 We wish you already a Merry Christmas and a Happy New Year!

Traveling with Food Allergies

Science.gov (United States)

... on traveling and dining out at restaurants with food allergies. Travel Tips for the U.S. and Other Countries Get information about medications and food labeling practices in select countries. Spam Control Text: ...

Disturbing, Disordered or Disturbed? Perspectives on the Definition of Problem Behavior in Educational Settings.

Science.gov (United States)

Wood, Frank H., Ed.; Lakin, K. Charlie, Ed.

The book contains five papers presented at a 1979 topical conference on the definition of emotional disturbance and behavioral disorders in educational settings. The first paper, by F. Wood, is titled "Defining Disturbing, Disordered, and Disturbed Behavior." Topics covered include ambivalence about defining deviant behavior by special educators,…

Carbon and water fluxes from ponderosa pine forests disturbed by wildfire and thinning.

Science.gov (United States)

Dore, S; Kolb, T E; Montes-Helu, M; Eckert, S E; Sullivan, B W; Hungate, B A; Kaye, J P; Hart, S C; Koch, G W; Finkral, A

2010-04-01

Disturbances alter ecosystem carbon dynamics, often by reducing carbon uptake and stocks. We compared the impact of two types of disturbances that represent the most likely future conditions of currently dense ponderosa pine forests of the southwestern United States: (1) high-intensity fire and (2) thinning, designed to reduce fire intensity. High-severity fire had a larger impact on ecosystem carbon uptake and storage than thinning. Total ecosystem carbon was 42% lower at the intensely burned site, 10 years after burning, than at the undisturbed site. Eddy covariance measurements over two years showed that the burned site was a net annual source of carbon to the atmosphere whereas the undisturbed site was a sink. Net primary production (NPP), evapotranspiration (ET), and water use efficiency were lower at the burned site than at the undisturbed site. In contrast, thinning decreased total ecosystem carbon by 18%, and changed the site from a carbon sink to a source in the first posttreatment year. Thinning also decreased ET, reduced the limitation of drought on carbon uptake during summer, and did not change water use efficiency. Both disturbances reduced ecosystem carbon uptake by decreasing gross primary production (55% by burning, 30% by thinning) more than total ecosystem respiration (TER; 33-47% by burning, 18% by thinning), and increased the contribution of soil carbon dioxide efflux to TER. The relationship between TER and temperature was not affected by either disturbance. Efforts to accurately estimate regional carbon budgets should consider impacts on carbon dynamics of both large disturbances, such as high-intensity fire, and the partial disturbance of thinning that is often used to prevent intense burning. Our results show that thinned forests of ponderosa pine in the southwestern United States are a desirable alternative to intensively burned forests to maintain carbon stocks and primary production.

UNderstanding uptake of Immunisations in TravellIng aNd Gypsy communities (UNITING): a qualitative interview study.

Science.gov (United States)

Jackson, Cath; Dyson, Lisa; Bedford, Helen; Cheater, Francine M; Condon, Louise; Crocker, Annie; Emslie, Carol; Ireland, Lana; Kemsley, Philippa; Kerr, Susan; Lewis, Helen J; Mytton, Julie; Overend, Karen; Redsell, Sarah; Richardson, Zoe; Shepherd, Christine; Smith, Lesley

2016-09-01

Gypsies, Travellers and Roma (referred to as Travellers) are less likely to access health services, including immunisation. To improve immunisation rates, we need to understand what helps and hinders individuals in these communities in taking up immunisations. (1) Investigate the barriers to and facilitators of acceptability and uptake of immunisations among six Traveller communities across four UK cities; and (2) identify possible interventions to increase uptake of immunisations in these Traveller communities that could be tested in a subsequent feasibility study. Three-phase qualitative study underpinned by the social ecological model. Phase 1: interviews with 174 Travellers from six communities: Romanian Roma (Bristol); English Gypsy/Irish Traveller (Bristol); English Gypsy (York); Romanian/Slovakian Roma (Glasgow); Scottish Showpeople (Glasgow); and Irish Traveller (London). Focus on childhood and adult vaccines. Phase 2: interviews with 39 service providers. Data were analysed using the framework approach. Interventions were identified using a modified intervention mapping approach. Phase 3: 51 Travellers and 25 service providers attended workshops and produced a prioritised list of potentially acceptable and feasible interventions. There were many common accounts of barriers and facilitators across communities, particularly across the English-speaking communities. Scottish Showpeople were the most similar to the general population. Roma communities experienced additional barriers of language and being in a new country. Men, women and service providers described similar barriers and facilitators. There was widespread acceptance of childhood and adult immunisation, with current parents perceived as more positive than their elders. A minority of English-speaking Travellers worried about multiple/combined childhood vaccines, adult flu and whooping cough. Cultural concerns about vaccines offered during pregnancy and about human papillomavirus were most evident in

Travelers' Health: Leishmaniasis, Visceral

Science.gov (United States)

... such as the United States reflects travel and immigration patterns. VL is uncommon in US travelers and ... whqlibdoc.who.int/trs/WHO_TRS_949_eng.pdf . Chapter 3 - Leishmaniasis, Cutaneous Chapter 3 - Leptospirosis File ...

Sleep Disturbances in Neurodevelopmental Disorders.

Science.gov (United States)

Robinson-Shelton, Althea; Malow, Beth A

2016-01-01

Sleep disturbances are extremely prevalent in children with neurodevelopmental disorders compared to typically developing children. The diagnostic criteria for many neurodevelopmental disorders include sleep disturbances. Sleep disturbance in this population is often multifactorial and caused by the interplay of genetic, neurobiological and environmental overlap. These disturbances often present either as insomnia or hypersomnia. Different sleep disorders present with these complaints and based on the clinical history and findings from diagnostic tests, an appropriate diagnosis can be made. This review aims to provide an overview of causes, diagnosis, and treatment of sleep disturbances in neurodevelopmental disorders that present primarily with symptoms of hypersomnia and/or insomnia.

Additive measures of travel time variability

DEFF Research Database (Denmark)

Engelson, Leonid; Fosgerau, Mogens

2011-01-01

This paper derives a measure of travel time variability for travellers equipped with scheduling preferences defined in terms of time-varying utility rates, and who choose departure time optimally. The corresponding value of travel time variability is a constant that depends only on preference...... parameters. The measure is unique in being additive with respect to independent parts of a trip. It has the variance of travel time as a special case. Extension is provided to the case of travellers who use a scheduled service with fixed headway....

Atmosphere-Ionosphere Electrodynamic Coupling

Science.gov (United States)

Sorokin, V. M.; Chmyrev, V. M.

Numerous phenomena that occur in the mesosphere, ionosphere, and the magnetosphere of the Earth are caused by the sources located in the lower atmosphere and on the ground. We describe the effects produced by lightning activity and by ground-based transmitters operated in high frequency (HF) and very low frequency (VLF) ranges. Among these phenomena are the ionosphere heating and the formation of plasma density inhomogeneities, the excitation of gamma ray bursts and atmospheric emissions in different spectral bands, the generation of ULF/ELF/VLF electromagnetic waves and plasma turbulence in the ionosphere, the stimulation of radiation belt electron precipitations and the acceleration of ions in the upper ionosphere. The most interesting results of experimental and theoretical studies of these phenomena are discussed below. The ionosphere is subject to the action of the conductive electric current flowing in the atmosphere-ionosphere circuit. We present a physical model of DC electric field and current formation in this circuit. The key element of this model is an external current, which is formed with the occurrence of convective upward transport of charged aerosols and their gravitational sedimentation in the atmosphere. An increase in the level of atmospheric radioactivity results in the appearance of additional ionization and change of electrical conductivity. Variation of conductivity and external current in the lower atmosphere leads to perturbation of the electric current flowing in the global atmosphere-ionosphere circuit and to the associated DC electric field perturbation both on the Earth's surface and in the ionosphere. Description of these processes and some results of the electric field and current calculations are presented below. The seismic-induced electric field perturbations produce noticeable effects in the ionosphere by generating the electromagnetic field and plasma disturbances. We describe the generation mechanisms of such experimentally

Integrating Remote Sensing, Field Observations, and Models to Understand Disturbance and Climate Effects on the Carbon Balance of the West Coast U.S.

Energy Technology Data Exchange (ETDEWEB)

B.E. Law; D. Turner; M. Goeckede

2010-06-01

GOAL: To develop and apply an approach to quantify and understand the regional carbon balance of the west coast states for the North American Carbon Program. OBJECTIVE: As an element of NACP research, the proposed investigation is a two pronged approach that derives and evaluates a regional carbon (C) budget for Oregon, Washington, and California. Objectives are (1) Use multiple data sources, including AmeriFlux data, inventories, and multispectral remote sensing data to investigate trends in carbon storage and exchanges of CO2 and water with variation in climate and disturbance history; (2) Develop and apply regional modeling that relies on these multiple data sources to reduce uncertainty in spatial estimates of carbon storage and NEP, and relative contributions of terrestrial ecosystems and anthropogenic emissions to atmospheric CO2 in the region; (3) Model terrestrial carbon processes across the region, using the Biome-BGC terrestrial ecosystem model, and an atmospheric inverse modeling approach to estimate variation in rate and timing of terrestrial uptake and feedbacks to the atmosphere in response to climate and disturbance. APPROACH: In performing the regional analysis, the research plan for the bottom-up approach uses a nested hierarchy of observations that include AmeriFlux data (i.e., net ecosystem exchange (NEE) from eddy covariance and associated biometric data), intermediate intensity inventories from an extended plot array partially developed from the PI's previous research, Forest Service FIA and CVS inventory data, time since disturbance, disturbance type, and cover type from Landsat developed in this study, and productivity estimates from MODIS algorithms. The BIOME-BGC model is used to integrate information from these sources and quantify C balance across the region. The inverse modeling approach assimilates flux data from AmeriFlux sites, high precision CO2 concentration data from AmeriFlux towers and four new calibrated CO2 sites

Robust Design of H-infinity Controller for a Launch Vehicle Autopilot against Disturbances

OpenAIRE

Graells, Antonio; Carrabina, Francisco

2016-01-01

Atmospheric flight phase of a launch vehicle is utilized to evaluate the performance of an H-infinity controller in the presence of disturbances. Dynamics of the vehicle is linearly modeled using time-varying parameters. An operating point was found to design a robust command tracker using H-infinity control theory that guarantees a stable maneuver. At the end, the controller was employed on the launch vehicle to assess the capability of control design on the linearized aerospace vehicle. Exp...

Valuation of travel time for international long-distance travel - results from the Fehmarn Belt stated choice experiment

DEFF Research Database (Denmark)

Mabit, Stefan Lindhard; Rich, Jeppe; Burge, Peter

2013-01-01

of travel time savings (VTTS). The final model, which was formulated as a nested logit model and included Box–Cox transformed travel time and cost attributes, revealed several interesting findings. Firstly, we found damping effects in both cost and time – most strongly in cost. Secondly, we found...... significant interactions among travel cost and time, and journey characteristics, such as distance and duration. This had direct impact on the VTTS, which was shown to decrease with distance and duration. Thirdly, we found that air travel implies a higher average VTTS, which is to be expected but rarely......The geographical scope of travel varies from short distances in urban areas to long distances across cities and countries. While urban travel has been widely analysed in the literature, travel over longer distances and particularly across countries, has received much less attention. While this may...

Analysis and evaluation of forest carbon projects and respective certification standards for the voluntary offset of greenhouse gas emissions; Analyse und Bewertung von Waldprojekten und entsprechender Standards zur freiwilligen Kompensation von Treibhausgasemissionen

Energy Technology Data Exchange (ETDEWEB)

Held, Christian; Tennigkeit, Timm; Techel, Grit; Seebauer, Matthias [UNIQUE forestry consultants GmbH, Freiburg (Germany)

2010-12-15

Forest based CO{sub 2} sequestration projects, regardless of their methodological approach, are always defined by the interaction of two carbon pools: (a) the CO{sub 2} stored in the forest ecosys-tem and (b) the CO{sub 2} present in the atmosphere. Forests are sinks for atmospheric carbon. This holds especially true for young or immature forests, if they are not disturbed and are not yet at equilibrium of increment, harvest and/or decay and harvest. This positive net sequestration of CO{sub 2} can be traded via emission reduction certificates, e.g. to offset emissions from industrial production, travelling and energy consumption. In contrast, the atmospheric pool increases if forests are destroyed leading to the release of the stored CO{sub 2}. This occurs if forest lands are converted into other land uses such as agricul-ture, or through forest management activities like harvesting or natural disturbances like for-est fires or pests. In all these cases forests become sources of CO{sub 2}. (orig.)

Traveling Safely with Medicines

Science.gov (United States)

... Medications Safely My Medicine List How to Administer Traveling Safely with Medicines Planes, trains, cars – even boats ... your trip, ask your pharmacist about how to travel safely with your medicines. Make sure that you ...

Estimating Household Travel Energy Consumption in Conjunction with a Travel Demand Forecasting Model

Energy Technology Data Exchange (ETDEWEB)

Garikapati, Venu M. [Systems Analysis and Integration Section, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401; You, Daehyun [Maricopa Association of Governments, 302 North First Avenue, Suite 300, Phoenix, AZ 85003; Zhang, Wenwen [School of City and Regional Planning, Center for Geographic Information Systems, Georgia Institute of Technology, 760 Spring Street, Suite 230, Atlanta, GA 30308; Pendyala, Ram M. [School of Sustainable Engineering and the Built Environment, Arizona State University, 660 South College Avenue, Tempe, AZ 85281; Guhathakurta, Subhrajit [School of City and Regional Planning, Center for Geographic Information Systems, Georgia Institute of Technology, 760 Spring Street, Suite 230, Atlanta, GA 30308; Brown, Marilyn A. [School of Public Policy, 685 Cherry Street, Georgia Institute of Technology, Atlanta, GA 30332; Dilkina, Bistra [School of Computational Science and Engineering, 266 Ferst Drive, Georgia Institute of Technology, Atlanta, GA 30332

2017-01-01

This paper presents a methodology for the calculation of the consumption of household travel energy at the level of the traffic analysis zone (TAZ) in conjunction with information that is readily available from a standard four-step travel demand model system. This methodology embeds two algorithms. The first provides a means of allocating non-home-based trips to residential zones that are the source of such trips, whereas the second provides a mechanism for incorporating the effects of household vehicle fleet composition on fuel consumption. The methodology is applied to the greater Atlanta, Georgia, metropolitan region in the United States and is found to offer a robust mechanism for calculating the footprint of household travel energy at the level of the individual TAZ; this mechanism makes possible the study of variations in the energy footprint across space. The travel energy footprint is strongly correlated with the density of the built environment, although socioeconomic differences across TAZs also likely contribute to differences in travel energy footprints. The TAZ-level calculator of the footprint of household travel energy can be used to analyze alternative futures and relate differences in the energy footprint to differences in a number of contributing factors and thus enables the design of urban form, formulation of policy interventions, and implementation of awareness campaigns that may produce more-sustainable patterns of energy consumption.

[Travel medicine for HIV-infected patients].

Science.gov (United States)

Rossi, M; Furrer, H

2001-06-01

Many HIV-infected persons travel from temperate zones to (sub)tropical destinations. HIV-specific immigration issues, medical resources abroad and problems regarding travelling with multiple medications have to be anticipated. When prescribing immunizations and specific chemoprophylaxis, the stage of immunodeficiency as well as drug interactions with antiretrovirals and medicaments against opportunistic infections have to be taken into account. Live vaccines may be contraindicated. Immunocompromised HIV-infected travellers have a higher risk for serious courses of diseases by enteropathogens. Therefore a good information about food hygiene is important and a prescription of an antibiotic to take in case of severe diarrhea may be indicated. A new antiretroviral combination therapy should not be started immediately before travelling to the tropics. The possibility to continue an established HIV treatment during travel has to be evaluated cautiously. With good pre-travel advice the risk of severe health problems is low for most HIV-infected travellers.

Experienced travel time prediction for congested freeways

OpenAIRE

Yildirimoglu, Mehmet; Geroliminis, Nikolaos

2013-01-01

Travel time is an important performance measure for transportation systems, and dissemination of travel time information can help travelers make reliable travel decisions such as route choice or departure time. Since the traffic data collected in real time reflects the past or current conditions on the roadway, a predictive travel time methodology should be used to obtain the information to be disseminated. However, an important part of the literature either uses instantaneous travel time ass...

Particulate carbon in the atmosphere

International Nuclear Information System (INIS)

Surakka, J.

1992-01-01

Carbonaceous aerosols are emitted to the atmosphere in combustion processes. Carbon particles are very small and have a long residence time in the air. Black Carbon, a type of carbon aerosol, is a good label when transport of combustion emissions in the atmosphere is studied. It is also useful tool in air quality studies. Carbon particles absorb light 6.5 to 8 times stronger than any other particulate matter in the air. Their effect on decreasing visibility is about 50 %. Weather disturbances are also caused by carbon emissions e.g. in Kuwait. Carbon particles have big absorption surface and capacity to catalyze different heterogenous reactions in air. Due to their special chemical and physical properties particulate carbon is a significant air pollution specie, especially in urban air. Average particulate carbon concentration of 5.7 μg/m 2 have been measured in winter months in Helsinki

Skin disorders among travellers returning from tropical and non-tropical countries consulting a travel medicine clinic.

Science.gov (United States)

Herbinger, K-H; Siess, C; Nothdurft, H D; von Sonnenburg, F; Löscher, T

2011-11-01

To evaluate the causes and risks for imported skin disorders among travellers. Data of 34,162 travellers returning from tropical and non-tropical countries and presenting at the outpatient travel medicine clinic of the University of Munich, Germany, between 1999 and 2009 were analyzed for this study. Of these, 12.2% were diagnosed with skin disorders. Main destinations visited were Asia (40%), Africa (27%) and Latin America (21%). Tourism in the form of adventure travel/backpacking (47%) and package holidays (23%) was the most common purpose of travel. The leading causes of skin disorders were arthropodal (23%), bacterial (22%), helminthic (11%), protozoan (6%), viral (6%), allergic (5%) and fungal (4%). The 10 most frequently diagnosed specific skin diseases associated with specific destinations were insect bites (17%, Southern Europe), cutaneous larva migrans (8%, Asia and Latin America), cutaneous leishmaniasis (2.4%, Mediterranean Region/Middle East), dengue fever (1.5%, Asia), rickettsioses (1.3%, Southern Africa), myiasis (0.8%, Central America), filarioses (0.7%, Africa), tick bites (0.6%, Central/Eastern Europe), schistosomiasis (0.6%, Africa) and tungiasis (0.6%, Africa). Travellers in sub-Saharan Africa had the highest relative risk of acquiring skin disorders. As more than 20% of all skin disorders among returned travellers were caused by arthropods and about 50% by infectious pathogens, pre-travel consultations should include specific prophylaxis and consider the most important risk factor for the travel destination. © 2011 Blackwell Publishing Ltd.

Self-reported infections during international travel and notifiable infections among returning international travellers, Sweden, 2009-2013.

Directory of Open Access Journals (Sweden)

Viktor Dahl

Full Text Available We studied food and water-borne diseases (FWDs, sexually transmitted diseases (STDs, vector-borne diseases (VBDs and diseases vaccinated against in the Swedish childhood vaccination programme among Swedish international travellers, in order to identify countries associated with a high number of infections. We used the national database for notifiable infections to estimate the number of FWDs (campylobacteriosis, salmonellosis, giardiasis, shigellosis, EHEC, Entamoeba histolytica, yersinosis, hepatitis A, paratyphoid fever, typhoid fever, hepatitis E, listeriosis, cholera, STIs (chlamydia, gonorrhoea and acute hepatitis B, VBDs (dengue fever, malaria, West Nile fever, Japanese encephalitis and yellow fever and diseases vaccinated against in the Swedish childhood vaccination programme (pertussis, measles, mumps, rubella, diphtheria acquired abroad 2009-2013. We obtained number and duration of trips to each country from a database that monthly collects travel data from a randomly selected proportion of the Swedish population. We calculated number of infections per country 2009-2013 and incidence/million travel days for the five countries with the highest number of infections. Thailand had the highest number of FWDs (7,697, incidence 191/million travel days, STIs (1,388, incidence 34/million travel days and VBDs (358, incidence 9/million travel days. France had the highest number of cases of diseases vaccinated against in the Swedish childhood vaccination programme (8, 0.4/million travel days. Swedish travellers contracted most infections in Thailand. Special focus should be placed on giving advice to travellers to this destination.

Infectious Risks of Traveling Abroad.

Science.gov (United States)

Chen, Lin H; Blair, Barbra M

2015-08-01

A popular leisure activity, international travel can be associated with some infections. The most common travel-related illnesses appear to be gastrointestinal, dermatologic, respiratory, and systemic febrile syndromes. The pretravel medical consultation includes immunizations, malaria chemoprophylaxis, self-treatment for traveler's diarrhea, and advice on the prevention of a myriad of other infectious causes including dengue, chikungunya, rickettsiosis, leptospirosis, schistosomiasis, and strongyloidiasis. Travel to locations experiencing outbreaks such as Ebola virus disease, Middle East respiratory syndrome, avian influenza, and chikungunya call for specific alerts on preventive strategies. After travel, evaluation of an ill traveler must explore details of exposure, including destinations visited; activities; ingestion of contaminated food or drinks; contact with vectors, animals, fresh water, or blood and body fluids; and other potential exposures. Knowledge of the geographic distribution of infectious diseases is important in generating the differential diagnoses and testing accordingly. Empiric treatment is sometimes necessary when suspicion of a certain diagnosis is strong and confirmatory tests are delayed or lacking, particularly for infections that are rapidly progressive (for example, malaria) or for which timing of testing is prolonged (such as leptospirosis).

Post-harmonised European National Travel Surveys

DEFF Research Database (Denmark)

Christensen, Linda; Sobrino Vázquez, Natalia

Look-up tables are collected and analysed for 12 European National Travel Surveys (NTS) in a harmonized way covering the age group 13-84 year. Travel behaviour measured as kilometres, time use and trips per traveller is compared. Trips per traveller are very similar over the countries whereas...... of walking trips rather similar with a higher level of cycling in the Netherlands, more public transport in Switzerland, and more air traffic in Sweden. Normally kilometres per respondent / inhabitant is used for national planning purpose and this is very affected by the share of mobile travellers...

Pre-Travel Medical Preparation of Business and Occupational Travelers: An Analysis of the Global TravEpiNet Consortium, 2009 to 2012.

Science.gov (United States)

Khan, Nomana M; Jentes, Emily S; Brown, Clive; Han, Pauline; Rao, Sowmya R; Kozarsky, Phyllis; Hagmann, Stefan H F; LaRocque, Regina C; Ryan, Edward T

2016-01-01

The aim of the study was to understand more about pre-travel preparations and itineraries of business and occupational travelers. De-identified data from 18 Global TravEpiNet clinics from January 2009 to December 2012 were analyzed. Of 23,534 travelers, 61% were non-occupational and 39% occupational. Business travelers were more likely to be men, had short times to departure and shorter trip durations, and commonly refused influenza, meningococcal, and hepatitis B vaccines. Most business travelers indicated that employers suggested the pre-travel health consultation, whereas non-occupational travelers sought consultations because of travel health concerns. Sub-groups of occupational travelers have characteristic profiles, with business travelers being particularly distinct. Employers play a role in encouraging business travelers to seek pre-travel consultations. Such consultations, even if scheduled immediately before travel, can identify vaccination gaps and increase coverage.

5 CFR 550.1404 - Creditable travel time.

Science.gov (United States)

2010-01-01

... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Creditable travel time. 550.1404 Section... ADMINISTRATION (GENERAL) Compensatory Time Off for Travel § 550.1404 Creditable travel time. (a) General. Subject... off for time in a travel status if— (1) The employee is required to travel away from the official duty...

CARLSON WAGONLIT TRAVEL

CERN Multimedia

2006-01-01

CARLSON WAGONLIT TRAVEL informs you that our agency will be closed from 22 December 2006 at 16:30 until 8 January 2007 at 8:30. For all URGENT MATTERS you can contact our CARLSON WAGONLIT TRAVEL branch at W.H.O. (Mr Pierre Plumettaz), phone: 022 791 55 95. We wish you already a Merry Christmas and a Happy New Year!

On the possibility for laboratory simulation of generation of Alfvén disturbances in magnetic tubes in the solar atmosphere

Directory of Open Access Journals (Sweden)

Prokopov P.A.

2016-03-01

Full Text Available The paper deals with generation of Alfvén plasma disturbances in magnetic flux tubes through exploding laser plasma in magnetized background plasma. Processes with similar effect of excitation of torsion-type waves seem to provide energy transfer from the solar photosphere to the corona. The studies were carried out at experimental stand KI-1 representing a high-vacuum chamber 1.2 m in diameter, 5 m in length, external magnetic field up to 500 G along the chamber axis, and up to 2·10–6 Torr pressure in operating mode. Laser plasma was produced when focusing the CO2 laser pulse on a flat polyethylene target, and then the laser plasma propagated in θ-pinch background hydrogen (or helium plasma. As a result, the magnetic flux tube 15–20 cm in radius was experimentally simulated along the chamber axis and the external magnetic field direction. Also, the plasma density distribution in the tube was measured. Alfvén wave propagation along the magnetic field was registered from disturbance of the magnetic field transverse component Bφ and field-aligned current Jz. The disturbances propagate at a near-Alfvén velocity 70–90 km/s and they are of left-hand circular polarization of the transverse component of magnetic field. Presumably, the Alfvén wave is generated by the magnetic laminar mechanism of collisionless interaction between laser plasma cloud and background. A right-hand polarized high-frequency whistler predictor was registered which propagated before the Alfvén wave at a velocity of 300 km/s. The polarization direction changed with the Alfvén wave coming. Features of a slow magnetosonic wave as a sudden change in background plasma concentration along with simultaneous displacement of the external magnetic field were found. The disturbance propagates at ~20–30 km/s velocity, which is close to that of ion sound at low plasma beta value. From preliminary estimates, the disturbance transfers about 10 % of the original energy of

Comparisons of continuous atmospheric CH4, CO2 and N2O measurements - results from a travelling instrument campaign at Mace Head

International Nuclear Information System (INIS)

Vardag, S.N.; Hammer, S.; Levin, I.; O'Doherty, S.; Spain, T.G.; Wastine, B.; Jordan, A.

2014-01-01

A 2-month measurement campaign with a Fourier transform infrared analyser as a travelling comparison instrument (TCI) was performed at the Advanced Global Atmospheric Gases Experiment (AGAGE) and World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) station at Mace Head, Ireland. The aim was to evaluate the compatibility of atmospheric methane (CH 4 ), carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) measurements of the routine station instrumentation, consisting of a gas chromatograph (GC) for CH 4 and N 2 O as well as a cavity ring-down spectroscopy (CRDS) system for CH 4 and CO 2 . The advantage of a TCI approach for quality control is that the comparison covers the entire ambient air measurement system, including the sample intake system and the data evaluation process. For initial quality and performance control, the TCI was run in parallel with the Heidelberg GC before and after the measurement campaign at Mace Head. Median differences between the Heidelberg GC and the TCI were well within the WMO inter-laboratory compatibility target for all three greenhouse gases. At Mace Head, the median difference between the station GC and the TCI were -0.04 nmol mol -1 for CH 4 and -0.37 nmol mol -1 for N 2 O (GC-TCI). For N 2 O, a similar difference (-0.40 nmol mol -1 ) was found when measuring surveillance or working gas cylinders with both instruments. This suggests that the difference observed in ambient air originates from a calibration offset that could partly be due to a difference between the WMON2O X2006a reference scale used for the TCI and the Scripps Institution of Oceanography (SIO-1998) scale used at Mace Head and in the whole AGAGE network. Median differences between the CRDS G1301 and the TCI at Mace Head were 0.12 nmol mol -1 for CH 4 and 0.14 μmol mol -1 for CO 2 (CRDS G1301 - TCI). The difference between both instruments for CO 2 could not be explained, as direct measurements of calibration gases show no such difference. The CH 4

Recommended vaccines for international travelers to India.

Science.gov (United States)

Verma, Ramesh; Khanna, Pardeep; Chawla, Suraj

2015-01-01

India's tourism industry generated 6.6% of the nation's Gross Domestic Product (GDP) during 2012. International travel to India is predicted to grow at an average annual rate of ∼ 8% over the next decade. The number of foreign tourists has increased by 9% to 5.8 million. Approximately 8% of travelers to developing countries require medical care during or after travel; the main diagnoses are vaccine-preventable diseases. Travelers to India can be exposed to various infectious diseases; water-borne, water-related, and zoonotic diseases may be imported to India where the disease is not endemic. The World Health Organization (WHO) emphasizes that all international travelers should be up to date with routine vaccinations. The recommended vaccinations for travelers to India vary according to the traveler's age, immunization history, existing medical conditions, duration, legal requirements for entry into countries being visited, travelers preferences, and values. Travelers should consult with a doctor so that there is sufficient time for completion of optimal vaccination schedules. No matter where traveling, one should be aware of potential exposure to certain organisms that can cause severely illnesses, even death. There is no doubt that vaccines have reduced or virtually eliminated many diseases that killed or severely disabled children and adults just a few generations ago. Thus, travelers must take recommended vaccines per schedule before traveling to India.

U.S. business travel

Science.gov (United States)

2003-10-01

Americans make more than 405 million long-distance business trips per year, : accounting for 16% of all long-distance travel, according to a : preliminary analysis of the National Household Travel Survey (NHTS). : Conducted from 2001 to 2002, the NHT...

Periodic travelling and non-travelling wave solutions of the nonlinear Klein-Gordon equation with imaginary mass

International Nuclear Information System (INIS)

Tang Xiaoyan; Shukla, Padma Kant

2008-01-01

Exact solutions, including the periodic travelling and non-travelling wave solutions, are presented for the nonlinear Klein-Gordon equation with imaginary mass. Some arbitrary functions are permitted in the periodic non-travelling wave solutions, which contribute to various high dimensional nonlinear structures

The intermediate disturbance hypothesis applies to tropical forests, but disturbance contributes little to tree diversity.

Science.gov (United States)

Bongers, Frans; Poorter, Lourens; Hawthorne, William D; Sheil, Douglas

2009-08-01

The intermediate disturbance hypothesis (IDH) predicts local species diversity to be maximal at an intermediate level of disturbance. Developed to explain species maintenance and diversity patterns in species-rich ecosystems such as tropical forests, tests of IDH in tropical forest remain scarce, small-scale and contentious. We use an unprecedented large-scale dataset (2504 one-hectare plots and 331,567 trees) to examine whether IDH explains tree diversity variation within wet, moist and dry tropical forests, and we analyse the underlying mechanism by determining responses within functional species groups. We find that disturbance explains more variation in diversity of dry than wet tropical forests. Pioneer species numbers increase with disturbance, shade-tolerant species decrease and intermediate species are indifferent. While diversity indeed peaks at intermediate disturbance levels little variation is explained outside dry forests, and disturbance is less important for species richness patterns in wet tropical rain forests than previously thought.

Travel Mode Use, Travel Mode Shift and Subjective Well-Being: Overview of Theories, Empirical Findings and Policy Implications

NARCIS (Netherlands)

Ettema, D.F.; Friman, M.; Gärling, Tommy; Olsson, Lars

2016-01-01

This chapter discusses how travel by different travel modes is related to primarily subjective well-being but also to health or physical well-being. Studies carried out in different geographic contexts consistently show that satisfaction with active travel modes is higher than travel by car and

38 CFR 60.5 - Travel.

Science.gov (United States)

2010-07-01

... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Travel. 60.5 Section 60.5... TEMPORARY LODGING § 60.5 Travel. As a condition for receiving temporary lodging under this part, a veteran must be required to travel either 50 or more miles, or at least two hours from his or her home to the...

Dynamic analysis of holiday travel behavior with integrated multimodal travel information usage : a life-oriented approach

NARCIS (Netherlands)

Wang, B.; Shao, C.; Ji, X.

2017-01-01

The Integrated Multimodal Travel Information (IMTI) plays an important role in the evolution process of holiday travel behaviour, which is seldom investigated. To fill this gap, this study analyses holiday travel behaviour dynamics with IMTI usage, based on the life-oriented approach. IMTI usage is

Pre-travel preparation practices among business travellers to tropical and subtropical destinations: results from the Athens International Airport Survey.

Science.gov (United States)

Pavli, Androula; Silvestros, Chrysovalantis; Patrinos, Stavros; Lymperi, Ioanna; Maltezou, Helena C

2014-01-01

The number of business travellers from Greece to tropical and subtropical areas has recently increased. The study aimed to assess travel health preparation practices of business travellers departing to Africa, the Middle East and Asia. A questionnaire-based survey was conducted at Athens International Airport, from 1st of November 2011 to 30th of April 2013. A total of 684 business travellers participated in the study; the majority were men (86.1%), of Greek nationality (95.3%), with tertiary education (90.8%) and employed (98%). Their mean age was 40 years; 62% and 26% of them were 35-49 and 19-34 years of age respectively. 84.8% were travelling alone. Most frequent destinations were the Middle East (46.8%) and sub-Saharan Africa (16%). For 23.5% of the travellers it was their first trip to a tropical or subtropical country. Only 58.8% pursued pre-travel health consultation; vaccination and malaria chemoprophylaxis were administered to 24.7% and 25.7% of the travellers, respectively. Hepatitis A and typhoid vaccination rates were lower than expected (70% and 35%, respectively). Nearly half of the travellers who visited malaria endemic areas did not receive any chemoprophylaxis. Having elementary education level, travelling to the Middle East or North Africa, travelling for less than 1 month duration, and staying in a house or a hotel were associated with a higher probability of not pursuing health consultation. Significant gaps were found in pre-travel health practices of business travellers departing to Africa, the Middle East and Asia. Strategies should be developed in order to improve awareness of business travellers. Copyright © 2013 Elsevier Ltd. All rights reserved.

Modelling effects of forest disturbance history on carbon balance: a deep learning approach using Landsat-time series.

Science.gov (United States)

Besnard, S.; Carvalhais, N.; Clevers, J.; Dutrieux, L.; Gans, F.; Herold, M.; Reichstein, M.; Jung, M.

2017-12-01

Forests play a crucial role in the global carbon (C) cycle, covering about 30% of the planet's terrestrial surface, accounting for 50% of plant productivity, and storing 45% of all terrestrial C. As such, forest disturbances affect the balance of terrestrial C dioxide (CO 2 ) exchange, with the potential of releasing large amounts of C into the atmosphere. Understanding and quantifying the effect of forest disturbance on terrestrial C metabolism is critical for improving forest C balance estimates and predictions. Here we combine remote sensing, climate, and eddy-covariance (EC) data to study forest land surface-atmosphere C fluxes at more than 180 sites globally. We aim to enhance understanding of C balance in forest ecosystems by capturing the ecological carry-over effect of disturbance historyon C fluxes. Our objectives are to (1) characterize forest disturbance history through the full temporal depth of the Landsat time series (LTS); and (2) to investigate lag and carry-over effects of forest dynamics and climate on ecosystem C fluxes using a data-driven recurrent neural network(RNN). The resulting data-driven model integrates carry-over effects of the system, using LTS, ecosystem productivity, and several abiotic factors. In this study, we show that our RNN algorithm is able to effectively calculate realistic seasonal, interannual, and across-site C flux variabilities based on EC, LTS, and climate data. In addition, our results demonstrate that a deep learning approach with embedded dynamic memory effects offorest dynamics is able to better capture lag and carry-over effects due to soil-vegetation feedback compared to a classic approach considering only the current condition of the ecosystem. Our study paves the way to produce accurate, high resolution carbon fluxes maps, providing morecomprehensive monitoring, mapping, and reporting of the carbon consequences of forest change globally.

How urban environment affects travel behavior? Integrated Choice and Latent Variable Model for Travel Schedules

DEFF Research Database (Denmark)

La Paix, Lissy; Bierlaire, Michel; Cherchi, Elisabetta

2013-01-01

The relationship between urban environment and travel behaviour is not a new problem. Neighbourhood characteristics may affect mobility of dwellers in different ways, such as frequency of trips, mode used, structure of the tours, and so on. At the same time, qualitative issues related...... to the individual attitude towards specific behaviour have recently become important in transport modelling contributing to a better understanding of travel demand. Following this research line, in this paper we study the effect of neighbourhood characteristics in the choice of the type of tours performed, but we...... assume that neighbourhood characteristics can also affect the individual propensity to travel and hence the choice of the tours throughout the propensity to travel. Since the propensity to travel is not observed, we employ hybrid choice models to estimate jointly the discrete choice of tours...

Vaccination for the expatriate and long-term traveler.

Science.gov (United States)

Shepherd, Suzanne M; Shoff, William H

2014-06-01

Duration of travel is an important factor in addressing travel health safety due to cumulative risk of exposure to illness and injury. The diverse group of expatriate and long-term business and leisure travelers present a different spectrum of issues for the travel medicine practitioner to address during consultation than does the short-term traveler, due to changes in travel patterns and activities, lifestyle alterations, and increased interaction with local populations. Immunization provides one safe and reliable method of preventing infectious illness in this group. We review travel patterns and available data on illnesses that they may be exposed to, including the increased risk of certain vaccine-preventable illnesses. We review the pre-travel management of these travelers, particularly the increased risk of certain vaccine-preventable illnesses as it applies to routine vaccines, recommended travel vaccines and required travel vaccines.

Value of travel time.

Science.gov (United States)

2016-08-01

Knowingly or not, people generally place economic value on their time. Wage workers are paid a rate per hour, and service providers may charge per hour of their time. In the transportation realm, travelers place a value on their travel time and have ...

U.S. holiday travel

Science.gov (United States)

2003-11-01

The Thanksgiving and Christmas/New Years holiday periods are among the busiest long-distance travel periods of the year. During the 6-day Thanksgiving travel period, the number of long-distance trips (to and from a destination 50 miles or more awa...

Intertidal soft-sediment community does not respond to disturbance as postulated by the intermediate disturbance hypothesis

Science.gov (United States)

Gerwing, Travis G.; Allen Gerwing, Alyssa M.; Macdonald, Tara; Cox, Kieran; Juanes, Francis; Dudas, Sarah E.

2017-11-01

The Intermediate Disturbance Hypothesis (IDH) predicts that disturbances of an intermediate frequency or intensity will maximize community biodiversity/richness. Once almost universally accepted, controversy now surrounds this hypothesis, and there have even been calls for its abandonment. Therefore, we experimentally evaluated if an infaunal community along the north coast of British Columbia, Canada, would respond to disturbances as predicted by the IDH. The characteristics of this soft-sediment intertidal mudflat (productivity, species pool, population growth rate) maximized our chances of finding evidence to support the IDH. More specifically, we tested if intermediate severities and frequencies of disturbance maximized infaunal community richness by mechanically disturbing sediment, and varying the intensity (0%, 25%, 50%, 75%, and 100% of the surface area of a plot disturbed) and frequency of sediment disturbance (never, once, twice, and every week during a four week period). No effect of frequency or intensity of sediment disturbance on community richness was observed. Further, none of our experimental treatments were statistically different than the controls. This is likely due to the subtle difference between successional stages in this soft-sediment habitat (difference of less than one taxa between treatments). Therefore, in habitats whose productivity, regional species pool, and population growth rates would otherwise suggest a response to disturbances as predicted by the IDH, minor differences between successional stages may result in richness patterns that deviate from those predicted by the IDH.

Climate change and forest disturbances

Science.gov (United States)

Virginia H. Dale; Linda A. Joyce; Steve McNulty; Ronald P. Neilson; Matthew P. Ayres; Michael D. Flannigan; Paul J. Hanson; Lloyd C. Irland; Ariel E. Lugo; Chris J. Peterson; Daniel Simberloff; Frederick J. Swanson; Brian J. Stocks; Michael Wotton

2001-01-01

This article examines how eight disturbances influence forest structure, composition, and function, and how climate change may influence the severity, frequency, and magnitude of disturbances to forests. We focus on examples from the United States, although these influences occur worldwide. We also consider options for coping with disturbance under changing climate....

Pediatric travel consultation in an integrated clinic.

Science.gov (United States)

Christenson , J C; Fischer , P R; Hale , D C; Derrick , D

2001-01-01

In May 1997, a pediatric travel service was created within a larger integrated University-County Health Department international travel clinic. The purpose of the service was to further enhance the travel advice and care provided to children and their parents or guardians. The current study was designed to describe the care of children in this setting and to compare the care of children seen in the Pediatric Travel Service with that of children seen by other providers. All pediatric patients (defined as individuals Mexico, South America, and Southeast Asia. When compared to travelers seen in the Regular Clinic, individuals in the Pediatric Travel Service group were more likely to travel for humanitarian work, and for parental work relocation. Persons in the Regular Clinic were more likely to travel to Mexico and Central America. They were also more likely to travel on vacation and for missionary work or study. Hepatitis B and tetanus-diphtheria booster vaccinations were given more frequently to travelers seen in the Regular Clinic. Also, ciprofloxacin and antimotility agents were more commonly prescribed in this group. No differences were noted in the duration of travel or in the time interval between clinic visit and departure. While general travel advice was considered to be similar in both clinic groups, some differences were observed in the frequency of administration of certain vaccines and prescriptions of medications. These differences were likely due to a difference in age in the two study groups. The high volume and success of the clinic suggest that integrated pediatric and adult travel services in a coordinated setting can be effective.

Gibbon travel paths are goal oriented.

Science.gov (United States)

Asensio, Norberto; Brockelman, Warren Y; Malaivijitnond, Suchinda; Reichard, Ulrich H

2011-05-01

Remembering locations of food resources is critical for animal survival. Gibbons are territorial primates which regularly travel through small and stable home ranges in search of preferred, limited and patchily distributed resources (primarily ripe fruit). They are predicted to profit from an ability to memorize the spatial characteristics of their home range and may increase their foraging efficiency by using a 'cognitive map' either with Euclidean or with topological properties. We collected ranging and feeding data from 11 gibbon groups (Hylobates lar) to test their navigation skills and to better understand gibbons' 'spatial intelligence'. We calculated the locations at which significant travel direction changes occurred using the change-point direction test and found that these locations primarily coincided with preferred fruit sources. Within the limits of biologically realistic visibility distances observed, gibbon travel paths were more efficient in detecting known preferred food sources than a heuristic travel model based on straight travel paths in random directions. Because consecutive travel change-points were far from the gibbons' sight, planned movement between preferred food sources was the most parsimonious explanation for the observed travel patterns. Gibbon travel appears to connect preferred food sources as expected under the assumption of a good mental representation of the most relevant sources in a large-scale space.

Vertical and oblique HF sounding with a network of synchronised ionosondes

Czech Academy of Sciences Publication Activity Database

Verhulst, T.; Altadill, D.; Mielich, J.; Reinisch, B.; Galkin, I.; Mouzakis, A.; Belehaki, A.; Burešová, Dalia; Stankov, S.; Blanch, E.; Kouba, Daniel

2017-01-01

Roč. 60, č. 8 (2017), s. 1644-1656 ISSN 0273-1177 R&D Project s: GA ČR(CZ) GC15-07281J Institutional support: RVO:68378289 Keywords : travelling ionospheric disturbances * digisonde * oblique sounding * ionospheric electromagnetic wave propagation * ionospheric measurement Subject RIV: DG - Athmosphere Science s, Meteorology OBOR OECD: Meteorology and atmospheric science s Impact factor: 1.401, year: 2016 http://www. science direct.com/ science /article/pii/S0273117717304593

The practice of travel medicine in Europe.

Science.gov (United States)

Schlagenhauf, P; Santos-O'Connor, F; Parola, P

2010-03-01

Europe, because of its geographical location, strategic position on trade routes, and colonial past, has a long history of caring for travellers' health. Within Europe, there is great diversity in the practice of travel medicine. Some countries have travel medicine societies and provisions for a periodic distribution of recommendations, but many countries have no national pre-travel guidelines and follow international recommendations such as those provided by the WHO. Providers of travel medicine include tropical medicine specialists, general practice nurses and physicians, specialist 'travel clinics', occupational physicians, and pharmacists. One of the core functions of the European Centre for Disease Prevention and Control-funded network of travel and tropical medicine professionals, EuroTravNet, is to document the status quo of travel medicine in Europe. A three-pronged approach is used, with a real-time online questionnaire, a structured interview with experts in each country, and web searching.

Risk of rabies exposure among travellers

NARCIS (Netherlands)

Wieten, R. W.; Tawil, S.; van Vugt, M.; Goorhuis, A.; Grobusch, M. P.

2015-01-01

In recent years, requests for rabies immunoglobulin have increased at Amsterdam's Academic Medical Center's travel clinic. Travellers who received rabies pre-exposure prophylaxis (PrEP) before travel departure have immunological memory that can quickly be activated by timely booster vaccinations

Global sale of green air travel supported using biodiesel

Energy Technology Data Exchange (ETDEWEB)

Wardle, D.A. [Auckland (New Zealand)

2003-02-01

The technical feasibility of operating commercial aircraft on low concentration biodiesel in kerosene blends is reviewed. Although the analysis is preliminary, it seems plausible that a biodiesel component could be introduced without significant modification to aircraft, airport infrastructure, and flight operations. The use of a biodiesel component, even for only a subset of flight operations, would open the possibility of giving all passengers, the world over, regardless of route, the option to pay a premium to make their journey on 'green' fuel (actually biodiesel). In this way, the airline industry could recover the additional cost of biodiesel in comparison to kerosene. The costs associated with such a scheme are estimated, as is consumer demand. Although the analysis is preliminary, the scheme appears commercially viable. From a humanitarian and/or environmental perspective, marketing flight on biodiesel as 'green air travel' is problematic. On the one hand, the use of biodiesel in aviation would reduce addition of carbon dioxide to the atmosphere and foster development of sustainable technology. On the other hand, it would require that agricultural resources be dedicated to air travel, nominally a luxury, in a world where agricultural resources appear destined to come under increasing strain merely to satisfy humanity's basic food and energy needs. A preliminary discussion of these issues is presented. It is hoped that this can serve as the starting point for further discussion, at an international level, to reach consensus on whether marketing of flight on biodiesel as 'green air travel' should be allowed to proceed, or whether it should be declared unethical. (author)

Monitoring travellers from Ebola-affected countries in New South Wales, Australia: what is the impact on travellers?

Directory of Open Access Journals (Sweden)

Jocelyn Chan

2017-01-01

Full Text Available Abstract Background Amidst an Ebola virus disease (EVD epidemic of unprecedented magnitude in west Africa, concerns about the risk of importing EVD led to the introduction of programs for the screening and monitoring of travellers in a number of countries, including Australia. Emerging reports indicate that these programs are feasible to implement, however rigorous evaluations are not yet available. We aimed to evaluate the program of screening and monitoring travellers in New South Wales. Methods We conducted a mixed methods study to evaluate the program of screening and monitoring travellers in New South Wales. We extracted quantitative data from the Notifiable Conditions Information Management System database and obtained qualitative data from two separate surveys of public health staff and arrivals, conducted by phone. Results Between 1 October 2014 and 13 April 2015, public health staff assessed a total of 122 out of 123 travellers. Six people (5% developed symptoms compatible with EVD and required further assessment. None developed EVD. Aid workers required lower levels of support compared to other travellers. Many travellers experienced stigmatisation. Public health staff were successful in supporting travellers to recognise and manage symptoms. Conclusion We recommend that programs for monitoring travellers should be tailored to the needs of different populations and include specific strategies to remediate stigmatisation.

Hepatitis B Vaccination Status among Japanese Travelers.

Science.gov (United States)

Yaita, Kenichiro; Yahara, Koji; Sakai, Yoshiro; Iwahashi, Jun; Masunaga, Kenji; Hamada, Nobuyuki; Watanabe, Hiroshi

2017-05-08

This study clarified the characteristics of travelers who received hepatitis B vaccinations. Subjects were 233 Japanese travelers who visited our clinic prior to travel. We summarized the characteristics of the clients and performed two comparative studies: first, we compared a hepatitis B-vaccinated group with an unvaccinated group; second, we compared a group that had completed the hepatitis B vaccine series with a group that did not complete the series. The hepatitis B vaccine was administered to 152 clients. Factors positively associated with the hepatitis B vaccination (after adjusting for age and sex) included the following: travel for business or travel as an accompanying family member; travel to Asia; travel for a duration of a month or more; and, inclusion of the vaccine in a company or organization's payment plan. Meanwhile, factors negatively associated with the vaccination were travel for leisure or education, and travel to North America or Africa. Among 89 record-confirmed cases, only 53 completed 3 doses. The completion rate was negatively associated with the scheduled duration of travel if it was from a month to less than a year (after adjusting for age and sex). The present study provides a basis for promoting vaccination compliance more vigorously among Japanese adults.

Upper atmospheric planetary-wave and gravity-wave observations

Science.gov (United States)

Justus, C. G.; Woodrum, A.

1973-01-01

Previously collected data on atmospheric pressure, density, temperature and winds between 25 and 200 km from sources including Meteorological Rocket Network data, ROBIN falling sphere data, grenade release and pitot tube data, meteor winds, chemical release winds, satellite data, and others were analyzed by a daily-difference method, and results on the magnitude of atmospheric perturbations interpreted as gravity waves and planetary waves are presented. Traveling planetary-wave contributions in the 25-85 km range were found to have significant height and latitudinal variation. It was found that observed gravity-wave density perturbations and wind are related to one another in the manner predicted by gravity-wave theory. It was determined that, on the average, gravity-wave energy deposition or reflection occurs at all altitudes except the 55-75 km region of the mesosphere.

Analysis of disturbance

International Nuclear Information System (INIS)

Ciala-Wein, H.; Stegmaier, W.

1977-12-01

The analyses of disturbances are the supposition for the development of processes and plants. They are very important in the field of nuclear testing plants. In this report are described the possibilities to register the circumstances of the disturbance in a pilot waste processing facility and a computer programme to interpret them. This is a first scheme and it will be necessary to complete it. (orig.) [de

Anthropological Invariants in Travel Behavior

OpenAIRE

Marchetti, C.

1994-01-01

Personal travel appears to be much more under the control of basic instinct than of economic drive. This may be the reason for the systematic mismatch between the results of cost benefit analysis and the actual behavior of travelers. In this paper a list of the basic instincts that drive and contain travelers' behavior has been put together, showing how they mesh with technological progress and economic constraints.

Psychological Aspects of Travel Information Presentation

NARCIS (Netherlands)

Dicke-Ogenia, M.

2012-01-01