The Suborbital Particle Aggregation and Collision Experiment (SPACE): Studying the Collision Behavior of Submillimeter-Sized Dust Aggregates on the Suborbital Rocket Flight REXUS 12

The Suborbital Particle Aggregation and Collision Experiment (SPACE) is a novel approach to study the collision properties of submillimeter-sized, highly porous dust aggregates. The experiment was designed, built and carried out to increase our knowledge about the processes dominating the first phase of planet formation. During this phase, the growth of planetary precursors occurs by agglomeration of micrometer-sized dust grains into aggregates of at least millimeters to centimeters in size. However, the formation of larger bodies from the so-formed building blocks is not yet fully understood. Recent numerical models on dust growth lack a particular support by experimental studies in the size range of submillimeters, because these particles are predicted to collide at very gentle relative velocities of below 1 cm/s that can only be achieved in a reduced-gravity environment. The SPACE experiment investigates the collision behavior of an ensemble of silicate-dust aggregates inside several evacuated glass containers which are being agitated by a shaker to induce the desired collisions at chosen velocities. The dust aggregates are being observed by a high-speed camera, allowing for the determination of the collision properties of the protoplanetary dust analog material. The data obtained from the suborbital flight with the REXUS (Rocket Experiments for University Students) 12 rocket will be directly implemented into a state-of-the-art dust growth and collision model

Microgravity experiments for the development of an empirical collision model for protoplanetary dust agglomerates

Die Entstehung von Planeten beginnt mit haftenden Stößen zwischen mikrometergroßen Staubpartikeln in protoplanetaren Scheiben. Mit zunehmender Größe der Agglomerate werden die Ergebnisse der Stöße komplexer. Neben dem Effekt der Haftung können sowohl Abprallen als auch verschiedene Formen der Fragmentation auftreten. Simulationen dieser Wachstumsprozesse sind auf genaue Kenntnisse der Massen- und Geschwindigkeitsabhängigkeit der Stoßergebnissen angewiesen. Im Rahmen dieser Arbeit wurde ein auf Experimenten basierendes Stoßmodell für poröse Staubagglomerate erstellt. Hierzu wurden zwei Schwerelosigkeitsexperimente durchgeführt und durch die Ergebnisse von bereits veröffentlichten Arbeiten ergänzt. Im Rahmen eines Fallturmexperimentes wurde das Haftverhalten von submillimetergroßen Staubagglomeraten untersucht. Anhand der Ergebnisse konnte eine massenabhängige Grenzgeschwindigkeit für den Übergang zu abprallenden Stößen bestimmt werden. Zusätzlich zur Haftung einzelner Staubagglomerate aneinander wurde die Entstehung von Agglomerat-Clustern beobachtet, welche fraktalen Charakter haben können. Stöße zwischen diesen Clustern führten auch bei Geschwindigkeiten zu Haftung, welche oberhalb der für einzelne Agglomerate abgeleiteten Haftgrenze liegen. In einem Parabelflugexperiment wurde nachgewiesen, dass in abprallenden Stößen zwischen zentimetergroßen Staubagglomeraten ein geringer Massenverlust auftreten kann. Es wurde gezeigt, dass die Stärke dieser Abrasion von der Stoßgeschwindigkeit der Agglomerate abhängt. Des Weiteren wurde für die Restitutionskoeffzienten der beobachteten Stöße der bekannte, mit der Geschwindigkeit abnehmende, Verlauf bestätigt. Für die Beschreibung der Stärke der Fragmentation poröser Staubagglomerate wurde ein massen- und geschwindigkeitsabhängiges Potenzgesetzes gefunden, welches berücksichtigt, dass größere Agglomerate bereits bei geringeren als den bislang angenommenen Stoßenergien zerbrechen. Schließlich wurden die Ergebnisse zu einem Stoßmodell zusammengefasst und in Hinblick auf das Wachstum von Agglomeraten diskutiert. Dabei hat sich gezeigt, dass unter Einbeziehung der Erosion ein Wachstum nur bis zu einer Größe von ca. 1 cm möglich ist. Die Entstehung von Planetesimalen ist daher auf zusätzliche Mechanismen, wie beispielsweise die Streaming Instability angewiesen. Eine Übertragung des Stoßmodells hin zu kleineren Staub- und Wassereispartikeln ergibt eine weitere Möglichkeit des Wachstums von großen Körpern durch Massentransfer.The formation of planets starts with sticking collisions between micrometer-sized dust particles in protoplanetary disks. With increasing size of the growing agglomerates, the collisional outcome becomes more complex. Agglomerates can not only stick, but also bounce of each other or fragment in different ways. Simulations of these growth processes depend on detailed knowledge of the mass and velocity dependency of the thresholds of the collisional outcome. In the scope of this thesis an experiment-based, empirical collision model for porous dust agglomerates was developed. For this, two microgravity experiments were conducted and complemented by the results of already published papers. The sticking behavior of submillimeter-sized dust agglomerates was studied in a drop tower experiment and used to derive a new mass dependent transition velocity for buncing collisions. Alongside the sticking of individual dust agglomerates, the formation of agglomerate-clusters, which could have fractal characteristics, was observed. Collisions between these clusters led to sticking, even at velocities clearly above the sticking threshold for collisions between individual agglomerates. It was demonstrated in a parabolic flight experiment, that bouncing collisions among centimeter-sized dust agglomerates can lead to a small mass loss. The strength of this abrasion depends on the collision velocity of the agglomerates. Furthermore, the experiment confirmed that the coeffcient of restitution decreases with increasing collision velocity. A new power law was found to describe the mass and velocity dependency of the strength of fragmentation of porous dust agglomerates. It reflects the fact that larger agglomerates fragment at lower collision energies. Finally, the results were used to derive a new collision model and discussed with regard to the potential growth of agglomerates in standard models for protoplanetary disk. Thereby it was shown, that the inclusion of erosion prohibits growth beyond the centimeter-size. Thus, the formation of planetesimals depends on additional processes like the streaming instability. However, an adaption of the collision model for smaller dust grains and water ice particles shows, that growth is possible for these grains

Faster HIV-1 Disease Progression among Brazilian Individuals Recently Infected with CXCR4-Utilizing Strains

Introduction: Primary HIV infection is usually caused by R5 viruses, and there is an association between the emergence of CCXR4-utilizing strains and faster disease progression. We characterized HIV-1 from a cohort of recently infected individuals in Brazil, predicted the virus's co-receptor use based on the env genotype and attempted to correlate virus profiles with disease progression. Methods: A total of 72 recently infected HIV patients were recruited based on the Serologic Testing Algorithm for Recent HIV Seroconversion and were followed every three to four months for up to 78 weeks. The HIV-1 V3 region was characterized by sequencing nine to twelve weeks after enrollment. Disease progression was characterized by CD4+ T-cell count decline to levels consistently below 350 cells/mu L. Results: Twelve out of 72 individuals (17%) were predicted to harbor CXCR4-utilizing strains; a baseline CD4,350 was more frequent among these individuals (p = 0.03). Fifty-seven individuals that were predicted to have CCR5-utilizing viruses and 10 individuals having CXCR4-utilizing strains presented with baseline CD4.350; after 78 weeks, 33 individuals with CCR5 strains and one individual with CXCR4 strains had CD4.350 (p = 0.001). There was no association between CD4 decline and demographic characteristics or HIV-1 subtype. Conclusions: Our findings confirm the presence of strains with higher in vitro pathogenicity during early HIV infection, suggesting that even among recently infected individuals, rapid progression may be a consequence of the early emergence of CXCR4-utilizing strains. Characterizing the HIV-1 V3 region by sequencing may be useful in predicting disease progression and guiding treatment initiation decisions.Brazilian Program for STD and AIDSBrazilian Program for STD and AIDSMinistry of Health [914/BRA/3014-UNESCO/Kallas]Ministry of HealthSao Paulo City Health DepartmentSao Paulo City Health Department [2004-0.168.922-7/Kallas]Fundacao de Amparo a Pesquisa do Estado de Sao PauloFundacao de Amparo a Pesquisa do Estado de Sao Paulo [04/15856-9/Diaz]Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Brazilian Ministry of EducationBrazilian Ministry of Educatio

Diagnostic performance of line-immunoassay based algorithms for incident HIV-1 infection

Background: Serologic testing algorithms for recent HIV seroconversion (STARHS) provide important information for HIV surveillance. We have previously demonstrated that a patient's antibody reaction pattern in a confirmatory line immunoassay (INNO-LIA™ HIV I/II Score) provides information on the duration of infection, which is unaffected by clinical, immunological and viral variables. In this report we have set out to determine the diagnostic performance of Inno-Lia algorithms for identifying incident infections in patients with known duration of infection and evaluated the algorithms in annual cohorts of HIV notifications. Methods: Diagnostic sensitivity was determined in 527 treatment-naive patients infected for up to 12 months. Specificity was determined in 740 patients infected for longer than 12 months. Plasma was tested by Inno-Lia and classified as either incident (< = 12 m) or older infection by 26 different algorithms. Incident infection rates (IIR) were calculated based on diagnostic sensitivity and specificity of each algorithm and the rule that the total of incident results is the sum of true-incident and false-incident results, which can be calculated by means of the pre-determined sensitivity and specificity. Results: The 10 best algorithms had a mean raw sensitivity of 59.4% and a mean specificity of 95.1%. Adjustment for overrepresentation of patients in the first quarter year of infection further reduced the sensitivity. In the preferred model, the mean adjusted sensitivity was 37.4%. Application of the 10 best algorithms to four annual cohorts of HIV-1 notifications totalling 2'595 patients yielded a mean IIR of 0.35 in 2005/6 (baseline) and of 0.45, 0.42 and 0.35 in 2008, 2009 and 2010, respectively. The increase between baseline and 2008 and the ensuing decreases were highly significant. Other adjustment models yielded different absolute IIR, although the relative changes between the cohorts were identical for all models Conclusions: The method can be used for comparing IIR in annual cohorts of HIV notifications. The use of several different algorithms in combination, each with its own sensitivity and specificity to detect incident infection, is advisable as this reduces the impact of individual imperfections stemming primarily from relatively low sensitivities and sampling bias

Addressing climate change with behavioral science: a global intervention tournament in 63 countries

Effectively reducing climate change requires marked, global behavior change. However, it is unclear which strategies are most likely to motivate people to change their climate beliefs and behaviors. Here, we tested 11 expert-crowdsourced interventions on four climate mitigation outcomes: beliefs, policy support, information sharing intention, and an effortful tree-planting behavioral task. Across 59,440 participants from 63 countries, the interventions’ effectiveness was small, largely limited to nonclimate skeptics, and differed across outcomes: Beliefs were strengthened mostly by decreasing psychological distance (by 2.3%), policy support by writing a letter to a future-generation member (2.6%), information sharing by negative emotion induction (12.1%), and no intervention increased the more effortful behavior—several interventions even reduced tree planting. Last, the effects of each intervention differed depending on people’s initial climate beliefs. These findings suggest that the impact of behavioral climate interventions varies across audiences and target behaviors

Current Directions in the Auricular

Electrical stimulation of the auricular vagus nerve (aVNS) is an emerging electroceutical technology in the field of bioelectronic medicine with applications in therapy. Artificial modulation of the afferent vagus nerve – a powerful entrance to the brain – affects a large number of physiological processes implicating interactions between the brain and body. Engineering aspects of aVNS determine its efficiency in application. The relevant safety and regulatory issues need to be appropriately addressed. In particular, in silico modeling acts as a tool for aVNS optimization. The evolution of personalized electroceuticals using novel architectures of the closed-loop aVNS paradigms with biofeedback can be expected to optimally meet therapy needs. For the first time, two international workshops on aVNS have been held in Warsaw and Vienna in 2017 within the scope of EU COST Action “European network for innovative uses of EMFs in biomedical applications (BM1309).” Both workshops focused critically on the driving physiological mechanisms of aVNS, its experimental and clinical studies in animals and humans, in silico aVNS studies, technological advancements, and regulatory barriers. The results of the workshops are covered in two reviews, covering physiological and engineering aspects. The present review summarizes on engineering aspects – a discussion of physiological aspects is provided by our accompanying article (Kaniusas et al., 2019). Both reviews build a reasonable bridge from the rationale of aVNS as a therapeutic tool to current research lines, all of them being highly relevant for the promising aVNS technology to reach the patient.European Cooperation in Science and TechnologyThe Austrian Research Promotion Agenc

Evaluation of daily maximum and minimum 2-m temperatures as simulated with the Regional Climate Model COSMO-CLM over Africa

The representation of the diurnal 2-m temperature cycle is challenging because of the many processes involved, particularly land-atmosphere interactions. This study examines the ability of the regional climate model COSMO-CLM (version 4.8) to capture the statistics of daily maximum and minimum 2-m temperatures (Tmin/Tmax) over Africa. The simulations are carried out at two different horizontal grid-spacings (0.22° and 0.44°), and are driven by ECMWF ERA-Interim reanalyses as near-perfect lateral boundary conditions. As evaluation reference, a high-resolution gridded dataset of daily maximum and minimum temperatures (Tmin/Tmax) for Africa (covering the period 2008–2010) is created using the regression-kriging-regression-kriging (RKRK) algorithm. RKRK applies, among other predictors, the remotely sensed predictors land surface temperature and cloud cover to compensate for the missing information about the temperature pattern due to the low station density over Africa. This dataset allows the evaluation of temperature characteristics like the frequencies of Tmin/Tmax, the diurnal temperature range, and the 90th percentile of Tmax. Although the large-scale patterns of temperature are reproduced well, COSMO-CLM shows significant under- and overestimation of temperature at regional scales. The hemispheric summers are generally too warm and the day-to-day temperature variability is overestimated over northern and southern extra-tropical Africa. The average diurnal temperature range is underestimated by about 2°C across arid areas, yet overestimated by around 2°C over the African tropics. An evaluation based on frequency distributions shows good model performance for simulated Tmin (the simulated frequency distributions capture more than 80% of the observed ones), but less well performance for Tmax (capture below 70%). Further, over wide parts of Africa a too large fraction of daily Tmax values exceeds the observed 90th percentile of Tmax, particularly across the African tropics. Thus, the representation of processes controlling Tmax including cloud-solar interaction, radiation processes, and ground heat fluxes should be improved by further model developments. The higher-resolution simulation (0.22°) is on average about 0.5°C warmer with a more pronounced overestimation of the higher percentiles of Tmax, and yields no clear benefit over the lower-resolution simulation