Techniques for Galactic Dust Measurements in the Heliosphere

Galactic interstellar dust (ISD) is the major ingredient in planetary formation. However, information on this important material has been extremely limited. Recently the Ulysses dust detector has identified and measured interstellar dust outside 1.8~AU from the Sun at ecliptic latitudes above $50^{\circ}$. Inside this distance it could not reliably distinguish interstellar from interplanetary dust. Modeling the Ulysses data suggests that up to 30 % of dust flux with masses above $10^{-16}\rm kg$ at 1~AU is of interstellar origin. From the Hiten satellite in high eccentric orbit about the Earth there are indications that ISD indeed reaches the Earth's orbit. Two new missions carrying dust detectors, Cassini and Stardust, will greatly increase our observational knowledge. In this paper we briefly review instruments used on these missions and compare their capabilities. The Stardust mission [{\em Brownlee et al.}, 1996] will analyze the local interstellar dust population by an in-situ chemical analyzer and collect ISD between 2 and 3~AU from the Sun. The dust analyzer on the Cassini mission will determine the interstellar dust flux outside Venus' orbit and will provide also some compositional information. Techniques to identify the ISD flux levels at 1~AU are described that can quantify the interstellar dust flux in high-Earth orbit (outside the debris belts) and provide chemical composition information of galactic dust.Comment: Accepted for Journal of Geophysical Research, 6 figures, Late

GEO debris and interplanetary dust: fluxes and charging behavior

In September 1996, a dust/debris detector: GORID was launched into the geostationary (GEO) region as a piggyback instrument on the Russian Express-2 telecommunications spacecraft. The instrument began its normal operation in April 1997 and ended its mission in July 2002. The goal of this work was to use GORID's particle data to identify and separate the space debris to interplanetary dust particles (IDPs) in GEO, to more finely determine the instrument's measurement characteristics and to derive impact fluxes. While the physical characteristics of the GORID impacts alone are insufficient for a reliable distinction between debris and interplanetary dust, the temporal behavior of the impacts are strong enough indicators to separate the populations based on clustering. Non-cluster events are predominantly interplanetary, while cluster events are debris. The GORID mean flux distributions (at mass thresholds which are impact speed dependent) for IDPs, corrected for dead time, are 1.35x10^{-4} m^{-2} s^{-1} using a mean detection rate: 0.54 d^{-1}, and for space debris are 6.1x10^{-4} m^{-2} s^{-1} using a mean detection rate: 2.5 d^{-1}. Beta-meteoroids were not detected. Clusters could be a closely-packed debris cloud or a particle breaking up due to electrostatic fragmentation after high charging.Comment: * Comments: 6 pages, 4 postscript figures, in Dust in Planetary Systems 2005, Krueger, H. and Graps, A. eds., ESA Publications, SP in press (2006). For high resolution version, see: http://www.mpi-hd.mpg.de/dustgroup/~graps/dips2005/GrapsetalDIPS2005.pd

High Concordance between Self-Reported Adherence, Treatment Outcome and Satisfaction with Care Using a Nine-Item Health Questionnaire in InfCareHIV

Background In this cross-sectional study we present an integrated analysis of a self-reported Health Questionnaire and socio-demographic and treatment outcome data from the national Swedish HIV cohort, InfCareHIV. Objectives To evaluate the Health Questionnaire and identify the main determinants of adherence. Methods A total of 2,846 patients answered a nine-item disease-specific Health Questionnaire between 2012 and 2014, corresponding to 44% of all active patients in the national InfCareHIV cohort. The questionnaire assessed patient related outcome measures (PROMs) regarding health and antiretroviral treatment (ART) and patient related experience measures (PREMs) regarding involvement in care and satisfaction with the care provider. Result We found the Health Questionnaire to be valid and reliable when used in ordinary clinical practice. There was a high concordance between self-reported adherence to ART in the past seven days and treatment outcome, with 94% of patients who reported optimal adherence having a viral load <50 copies/ml. The main determinants of optimal adherence were heterosexual transmission path, being born in Sweden, being male, not reporting experience of ART side effects and being fully satisfied with care. Conclusion The nine-item Health Questionnaire can identify patients at risk of treatment failure, those in need of clinical assessment of adverse events and those with impaired physical health

Development and psychometric testing of a barriers to HIV testing scale among individuals with HIV infection in Sweden; The Barriers to HIV testing scale-Karolinska version

© 2015 Wiklander et al. Background: Barriers to HIV testing experienced by individuals at risk for HIV can result in treatment delay and further transmission of the disease. Instruments to systematically measure barriers are scarce, but could contribute to improved strategies for HIV testing. Aims of this study were to develop and test a barriers to HIV testing scale in a Swedish context. Methods: An 18-item scale was developed, based on an existing scale with addition of six new items related to fear of the disease or negative consequences of being diagnosed as HIV-infected. Items were phrased as statements about potential barriers with a three-point response format representing not important, somewhat important, and very important. The scale was evaluated regarding missing values, floor and ceiling effects, exploratory factor analysis, and internal consistencies. Results: The questionnaire was completed by 292 adults recently diagnosed with HIV infection, of whom 7 were excluded (≥9 items missing) and 285 were included (≥12 items completed) in the analyses. The participants were 18-70 years old (mean 40.5, SD 11.5), 39 % were females and 77 % born outside Sweden. Routes of transmission were heterosexual transmission 63 %, male to male sex 20 %, intravenous drug use 5 %, blood product/transfusion 2 %, and unknown 9 %. All scale items had <3 % missing values. The data was feasible for factor analysis (KMO = 0.92) and a four-factor solution was chosen, based on level of explained common variance (58.64 %) and interpretability of factor structure. The factors were interpreted as; personal consequences, structural barriers, social and economic security, and confidentiality. Ratings on the minimum level (suggested barrier not important) were common, resulting in substantial floor effects on the scales. The scales were internally consistent (Cronbach's aα 0.78-0.91). Conclusions: This study gives preliminary evidence of the scale being feasible, reliable and valid to identify different types of barriers to HIV testing

In situ observations of waves in Venus’s polar lower thermosphere with Venus Express aerobraking

Waves are ubiquitous phenomena found in oceans and atmospheres alike. From the earliest formal studies of waves in the Earth’s atmosphere to more recent studies on other planets, waves have been shown to play a key role in shaping atmospheric bulk structure, dynamics and variability1, 2, 3, 4. Yet, waves are difficult to characterize as they ideally require in situ measurements of atmospheric properties that are difficult to obtain away from Earth. Thus, we have incomplete knowledge of atmospheric waves on planets other than our own, and we are thereby limited in our ability to understand and predict planetary atmospheres. Here we report the first ever in situ observations of atmospheric waves in Venus’s thermosphere (130–140 km) at high latitudes (71.5°–79.0°). These measurements were made by the Venus Express Atmospheric Drag Experiment (VExADE)5 during aerobraking from 24 June to 11 July 2014. As the spacecraft flew through Venus’s atmosphere, deceleration by atmospheric drag was sufficient to obtain from accelerometer readings a total of 18 vertical density profiles. We infer an average temperature of T = 114 ± 23 K and find horizontal wave-like density perturbations and mean temperatures being modulated at a quasi-5-day period

Constraints on the Huygens landing site topography from the Surface Science Package Acoustic Properties Instrument

We present analysis of the results from the Huygens acoustic sounder instrument. The sounder sees a relatively smooth terrain, with specular reflectance characteristics

Io revealed in the Jovian dust streams

The Jovian dust streams are high-speed bursts of submicron-sized particles traveling in the same direction from a source in the Jovian system. Since their discovery in 1992, they have been observed by three spacecraft: Ulysses, Galileo and Cassini. The source of the Jovian dust streams is dust from Io's volcanoes. The charged and traveling dust stream particles have particular signatures in frequency space and in real space. The frequency-transformed Galileo dust stream measurements show different signatures, varying orbit-to-orbit during Galileo's first 29 orbits around Jupiter. Time-frequency analysis demonstrates that Io is a localized source of charged dust particles. Aspects of the particles' dynamics can be seen in the December-2000 joint Galileo-Cassini dust stream measurements. To match the travel times, the smallest dust particles could have the following range of parameters: radius: 6nm, density: 1.35-1.75gr/cm$^3$, sulfur charging conditions, which produce dust stream speeds: 220|450km/sec (Galileo|Cassini) and charge potentials: 5.5|6.3Volt (Galileo|Cassini).Comment: 8 pages, 5 postscript figures, latex, uses esapub.cls, aa.bst. Version with high-resolution figures can be found at http://www.mpi-hd.mpg.de/dustgroup/~graps/thesis

Solid phase synthesis of functionalised SAM-forming alkanethiol-oligoethyleneglycols

We present an efficient solid phase synthesis methodology that provides easy access to a range of functionalised long-chain alkanethiol-oligoethyleneglycols that form well-defined self-assembled monolayers on gold and are compatible with pre- or post-assembly conjugation of (bio)molecules. We demonstrate the versatility of our synthetic route by synthesising LCAT-OEGs with a range of functional moieties, including peptides, electro-active redox groups, chemical handles for post-assembly conjugation of (bio)molecules, and demonstrate the application of our LCAT-OEG monolayers in immunosensing, where they show good biocompatibility with minimal biofouling