Stellar-Mass-Dependent Disk Structure in Coeval Planet-Forming Disks

Previous studies suggest that the planet-forming disks around very-low-mass stars/brown dwarfs may be flatter than those around more massive stars, in contrast to model predictions of larger scale heights for gas-disks around lower-mass stars. We conducted a statistically robust study to determine whether there is evidence for stellar-mass-dependent disk structure in planet-forming disks. We find a statistically significant difference in the Spitzer/IRAC color distributions of disks around very-low-mass and low-mass stars all belonging to the same star-forming region, the Chamaeleon I star-forming region. We show that self consistently calculated disk models cannot fit the median spectral energy distributions (SEDs) of the two groups. These SEDs can be only explained by flatter disk models, consistent with the effect of dust settling in disks. We find that relative to the disk structure predicted for flared disks the required reduction in disk scale height is anti-correlated with the stellar mass, i.e. disks around lower-mass stars are flatter. Our results show that the initial and boundary conditions of planet formation are stellar-mass-dependent, an important finding that must be considered in planet formation models.Comment: Astrophysical Journal, in pres

Multiplicity among chemically peculiar stars II. Cool magnetic Ap stars

We present new orbits for sixteen Ap spectroscopic binaries, four of which might in fact be Am stars, and give their orbital elements. Four of them are SB2 systems: HD 5550, HD 22128, HD 56495 and HD 98088. The twelve other stars are : HD 9996, HD 12288, HD 40711, HD 54908, HD 65339, HD 73709, HD 105680, HD 138426, HD 184471, HD 188854, HD 200405 and HD 216533. Rough estimates of the individual masses of the components of HD 65339 (53 Cam) are given, combining our radial velocities with the results of speckle interferometry and with Hipparcos parallaxes. Considering the mass functions of 74 spectroscopic binaries from this work and from the literature, we conclude that the distribution of the mass ratio is the same for cool Ap stars as for normal G dwarfs. Therefore, the only differences between binaries with normal stars and those hosting an Ap star lie in the period distribution: except for the case of HD 200405, all orbital periods are longer than (or equal to) 3 days. A consequence of this peculiar distribution is a deficit of null eccentricities. There is no indication that the secondary has a special nature, like e.g. a white dwarf.Comment: 31 pages, 15 figures, A&A accepte

Service User Involvement - SUI Newsletter - Ausgabe Mai 20221

Der jährlich erscheinende Newsletter berichtet über Aktivitäten rund um Service User Involvement an Hochschulen im deutschsprachigen Raum. Sie finden in dieser Ausgabe folgende Beiträge: Zu Beginn berichten Bärbel Haag, Thomas Heidenreich und Bettina Müller von der Hochschule Esslingen über die neue Zusammenarbeit mit Bildungsfachkräften, die z. B. Input zu Inklusions- und Exklusionserfahrungen von Menschen mit Behinderungen teilgeben. Daran anschließen kann David Dörrer, der uns über das Annelie-Wellensiek-Zentrum für Inklusive Bildung an der Pädagogischen Hochschule Heidelberginformiert, an der Menschen mit und ohne Behinderungserfahrungen gemein-sam zu Querschnittsaufgaben der Inklusion forschen und lehren. Es folgt ein Bericht und Plädoyer aus Berlin von Reinhard Burtscher und Anne Schöbel über Lerner-Expert:innen, die durch ihre Erfahrungsberichte dem Thema „Alphabetisierung und Grundbildung“ ein Gesicht geben. Katharina Lutz und Benjamin Benz machen uns auf den Sozial-Wissenschaftsladen aufmerksam, der das gemeinsame Forschen für zivilgesellschaftliche Vertreter_innen, Praktiker_innen und Hochschulangehörige in Lehrforschungsprojekten und im Rahmen von Bachelor- und Masterarbeiten ermöglicht. Forschend geht es auch weiter mit Katharina Scholz, die sich mit Lehr-Evaluation für Seminare mit Beteiligung von Adressat*innen befasst und von neuen Vorhaben aus der HAW Hamburg berichtet. Kornelia Birkemeyer stellt das Projekt EX-IN vor, berichtet als Genesungsbegleiterin über die Kooperation mit der Hochschule Esslingen und liefert Antworten auf die Frage: „Warum brauchen Studierende von sozialer Arbeit die Hilfe von Service Usern?“. Um Gesungsbegleiter*innen als Teil eines trialogischen Konzeptes geht es auch bei der interaktiven Online-Plattform TriNetz, die von Christel Baatz-Kolbe und Christoph Walther vorgestellt wird. Die Plattform hat eine Lotsenfunktion und vermittelt zwischen Interessierten, Ausbildungsstätten und potentiellen Arbeitgebern. Bei Birgit Mayrhofer und Laura Ressler geht es gleichermaßen um die Peer-Arbeit von Genesungsbegleiter*innen. Sie stellen ihr Masterforschungsprojekt vor, das sich mit der Rollenkonstruktion der Peer-Arbeit befasst. Die Peer-Begleiterin Barbara Kohlmann vom Projekt „Upsides“ verabschiedet uns mit ihren Gedanken zu Peer-Arbeit in Zeiten der Covid-19-Pandemie. Am Ende des Newsletters finden Sie noch Hinweise über aktuelle Publikationen und anstehende Termine zum Thema Service User Involvement.Unknow

Rheological and biological properties of a hydrogel support for cells intended for intervertebral disc repair

<p>Abstract</p> <p>Background</p> <p>Cell-based approaches towards restoration of prolapsed or degenerated intervertebral discs are hampered by a lack of measures for safe administration and placement of cell suspensions within a treated disc. In order to overcome these risks, a serum albumin-based hydrogel has been developed that polymerizes after injection and anchors the administered cell suspension within the tissue.</p> <p>Methods</p> <p>A hydrogel composed of chemically activated albumin crosslinked by polyethylene glycol spacers was produced. The visco-elastic gel properties were determined by rheological measurement. Human intervertebral disc cells were cultured <it>in vitro </it>and <it>in vivo </it>in the hydrogel and their phenotype was tested by reverse-transcriptase polymerase chain reaction. Matrix production and deposition was monitored by immuno-histology and by biochemical analysis of collagen and glycosaminoglycan deposition. Species specific <it>in situ </it>hybridization was performed to discriminate between cells of human and murine origin in xenotransplants.</p> <p>Results</p> <p>The reproducibility of the gel formation process could be demonstrated. The visco-elastic properties were not influenced by storage of gel components. <it>In vitro </it>and <it>in vivo </it>(subcutaneous implants in mice) evidence is presented for cellular differentiation and matrix deposition within the hydrogel for human intervertebral disc cells even for donor cells that have been expanded in primary monolayer culture, stored in liquid nitrogen and re-activated in secondary monolayer culture. Upon injection into the animals, gels formed spheres that lasted for the duration of the experiments (14 days). The expression of cartilage- and disc-specific mRNAs was maintained in hydrogels <it>in vitro </it>and <it>in vivo</it>, demonstrating the maintenance of a stable specific cellular phenotype, compared to monolayer cells. Significantly higher levels of hyaluronan synthase isozymes-2 and -3 mRNA suggest cell functionalities towards those needed for the support of the regeneration of the intervertebral disc. Moreover, mouse implanted hydrogels accumulated 5 times more glycosaminoglycans and 50 times more collagen than the <it>in vitro </it>cultured gels, the latter instead releasing equivalent quantities of glycosaminoglycans and collagen into the culture medium. Matrix deposition could be specified by immunohistology for collagen types I and II, and aggrecan and was found only in areas where predominantly cells of human origin were detected by species specific <it>in situ </it>hybridization.</p> <p>Conclusions</p> <p>The data demonstrate that the hydrogels form stable implants capable to contain a specifically functional cell population within a physiological environment.</p

Stellar, brown dwarf and multiple star properties from a radiation hydrodynamical simulation of star cluster formation

We report the statistical properties of stars, brown dwarfs and multiple systems obtained from the largest radiation hydrodynamical simulation of star cluster formation to date that resolves masses down to the opacity limit for fragmentation (a few Jupiter masses). The initial conditions are identical to those of previous barotropic calculations published by Bate, but this time the calculation is performed using a realistic equation of state and radiation hydrodynamics. The calculation uses sink particles to model 183 stars and brown dwarfs, including 28 binaries and 12 higher-order multiple systems, the properties of which are compared the results from observational surveys. We find that the radiation hydrodynamical/sink particle simulation reproduces many observed stellar properties very well. In particular, whereas using a barotropic equation of state produces more brown dwarfs than stars, the inclusion of radiative feedback results in a stellar mass function and a ratio of brown dwarfs to stars in good agreement with observations of Galactic star-forming regions. In addition, many of the other statistical properties of the stars and brown dwarfs are in reasonable agreement with observations, including multiplicity as a function of primary mass, the frequency of very-low-mass binaries, and general trends for the mass ratio and separation distributions of binaries. We also examine the velocity dispersion of the stars, the distributions of disc truncation radii due to dynamical interactions, and coplanarity of orbits and sink particle spins in multiple systems. Overall, the calculation produces a cluster of stars whose statistical properties are difficult to distinguish from observed systems, implying that gravity, hydrodynamics, and radiative feedback are the primary ingredients for determining the origin of the statistical properties of low-mass stars.Comment: Accepted for publication in MNRAS, 33 pages, 23 figures. Animations can be found at http://www.astro.ex.ac.uk/people/mbate

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

VASP regulates leukocyte infiltration, polarization, and vascular repair after ischemia

In ischemic vascular diseases, leukocyte recruitment and polarization are crucial for revascularization and tissue repair. We investigated the role of vasodilator-stimulated phosphoprotein (VASP) in vascular repair. After hindlimb ischemia induction, blood flow recovery, angiogenesis, arteriogenesis, and leukocyte infiltration into ischemic muscles in VASP−/− mice were accelerated. VASP deficiency also elevated the polarization of the macrophages through increased signal transducer and activator of transcription (STAT) signaling, which augmented the release of chemokines, cytokines, and growth factors to promote leukocyte recruitment and vascular repair. Importantly, VASP deletion in bone marrow–derived cells was sufficient to mimic the increased blood flow recovery of global VASP−/− mice. In chemotaxis experiments, VASP−/− neutrophils/monocytes were significantly more responsive to M1-related chemokines than wild-type controls. Mechanistically, VASP formed complexes with the chemokine receptor CCR2 and β-arrestin-2, and CCR2 receptor internalization was significantly reduced in VASP−/− leukocytes. Our data indicate that VASP is a major regulator of leukocyte recruitment and polarization in postischemic revascularization and support a novel role of VASP in chemokine receptor trafficking