Shadows and cavities in protoplanetary disks: HD163296, HD141569A, and HD150193A in polarized light

The morphological evolution of dusty disks around young (few Myr-old) stars is pivotal to better understand planet formation. Since both dust grains and the global disk geometry evolve on short timescale, high-resolution imaging of a sample of objects may provide important hints towards such an evolution. We enlarge the sample of protoplanetary disks imaged in polarized light with high-resolution by observing the Herbig Ae/Be stars HD163296, HD141569A, and HD150193A. We integrate our data with previous datasets to paint a larger picture of their morphology. We report a weak detection of the disk around HD163296 in both H and Ks band. The disk is resolved as a broken ring structure with a significan surface brightness drop inward of 0.6 arcsec. No sign of extended polarized emission is detected from the disk around HD141569A and HD150193A. We propose that the absence of scattered light in the inner 0.6 arcsec around HD163296 and the non-detection of the disk around HD150193A may be due to similar geometric factors. Since these disks are known to be flat or only moderately flared, self-shadowing by the disk inner wall is the favored explanation. We show that the polarized brightness of a number of disks is indeed related to their flaring angle. Other scenarios (such as dust grain growth or interaction with icy molecules) are also discussed. On the other hand, the non-detection of HD141569A is consistent with previous datasets revealing the presence of a huge cavity in the dusty disk.Comment: 10 pages, 5 figures; accepted by Astronomy & Astrophysic

Small vs large dust grains in transitional disks: do different cavity sizes indicate a planet?

Transitional disks represent a short stage of the evolution of circumstellar material. Studies of dust grains in these objects can provide pivotal information on the mechanisms of planet formation. Dissimilarities in the spatial distribution of small (micron-size) and large (millimeter-size) dust grains have recently been pointed out. Constraints on the small dust grains can be obtained by imaging the distribution of scattered light at near-infrared wavelengths. We aim at resolving structures in the surface layer of transitional disks (with particular emphasis on the inner 10 - 50 AU), thus increasing the scarce sample of high resolution images of these objects. We obtained VLT/NACO near-IR high-resolution polarimetric differential imaging observations of SAO 206462 (HD135344B). This technique allows one to image the polarized scattered light from the disk without any occulting mask and to reach an inner working angle of 0.1''. A face-on disk is detected in H and Ks bands between 0.1'' and 0.9''. No significant differences are seen between the H and Ks images. In addition to the spiral arms, these new data allow us to resolve for the first time an inner cavity for small dust grains. The cavity size (about 28 AU) is much smaller than what is inferred for large dust grains from (sub)mm observations (39 to 50 AU). The interaction between the disk and potential orbiting companion(s) can explain both the spiral arm structure and the discrepant cavity sizes for small and large dust grains. One planet may be carving out the gas (and, thus, the small grains) at 28 AU, and generating a pressure bump at larger radii (39 AU), which holds back the large grains. We analytically estimate that, in this scenario, a single giant planet (with a mass between 5 and 15 Jupiter masses) at 17 to 20 AU from the star is consistent with the observed cavity sizes.Comment: 11 pages, 6 figures; accepted for publication in A&

Giant Keplerate molecule Fe30 - the first octopole magnet

The multipole expansion technique is applied to one of the largest magnetic molecules, Fe30. The molecule's dipole, toroid and quadrupole magnetic moments are equal to zero (in the absence of magnetic field) so the multipole expansion starts from the octopole moment. Probably the Fe30 molecule is the most symmetrical magnetic body synthesized so far. The magnetization process is considered theoretically in different geometries. Some components of the octopole moment experience a jump while the magnetization rises linearly up to its saturation value. An elementary octopole moment consisting of four magnetic dipoles is proposed as a hint for designing of an experiment for measurement of octopole magnetic moment components.Comment: 7 pages, 9 figure

Regulatory T Cells and IL-10 Independently Counterregulate Cytotoxic T Lymphocyte Responses Induced by Transcutaneous Immunization

The imidazoquinoline derivate imiquimod induces inflammatory responses and protection against transplanted tumors when applied to the skin in combination with a cognate peptide epitope (transcutaneous immunization, TCI). Here we investigated the role of regulatory T cells (T(reg)) and the suppressive cytokine IL-10 in restricting TCI-induced cytotoxic T lymphocyte (CTL) responses.TCI was performed with an ointment containing the TLR7 agonist imiquimod and a CTL epitope was applied to the depilated back skin of C57BL/6 mice. Using specific antibodies and FoxP3-diphteria toxin receptor transgenic (DEREG) mice, we interrogated inhibiting factors after TCI: by depleting FoxP3(+) regulatory T cells we found that specific CTL-responses were greatly enhanced. Beyond this, in IL-10 deficient (IL-10(-/-)) mice or after blocking of IL-10 signalling with an IL-10 receptor specific antibody, the TCI induced CTL response is greatly enhanced indicating an important role for this cytokine in TCI. However, by transfer of T(reg) in IL-10(-/-) mice and the use of B cell deficient JHT(-/-) mice, we can exclude T(reg) and B cells as source of IL-10 in the setting of TCI.We identify T(reg) and IL-10 as two important and independently acting suppressors of CTL-responses induced by transcutaneous immunization. Advanced vaccination strategies inhibiting T(reg) function and IL-10 release may lead the development of effective vaccination protocols aiming at the induction of T cell responses suitable for the prophylaxis or treatment of persistent infections or tumors

Association Between Changes in Post-hospital Cardiac Symptoms and Changes in Acute Coronary Syndrome-Induced Symptoms of Post-traumatic Stress.

Background After acute coronary syndrome (ACS), one in eight patients develops clinically significant symptoms of Post-traumatic stress disorder (PTSD). We hypothesized that changes in cardiac symptoms from 3 to 12 months after ACS are associated with changes in ACS-induced PTSD symptoms. Methods At 3 (n = 154) and/or 12 months (n = 106) post-ACS, patients (n = 156, mean age 59 years, 85% men) completed a clinical interview assessing chest tightness/pain (at rest and/or during exertion), heartbeat symptoms (heart palpitations, racing of heart, heart stumbling or skipping a beat) and PTSD symptoms during the prior 4 weeks. Random mixed regression models examined the association between the onset (or remission) from 3 to 12 months in cardiac symptoms with changes in PTSD symptoms, adjusting for a range of potential predictors of ACS-induced PTSD symptoms. Results The onset of chest tightness/pain [estimate = 0.588, 95% confidence interval: 0.275, 0.090; p < 0.001] and of heartbeat symptoms [0.548 (0.165, 0.931); p = 0.005] from 3 to 12 months was independently associated with an increase in total PTSD symptoms. There were also independent associations between the onset of chest tightness/pain and heartbeat symptoms with an increase in PTSD symptom clusters. Specifically, the onset of chest tightness/pain showed associations with an increase in re-experiencing [0.450 (0.167, 0.733); p = 0.027] and avoidance/numbing [0.287 (0.001, 0.574); p = 0.049]. The onset of heartbeat symptoms showed associations with an increase in re-experiencing [0.392 (0.045, 0.739); p = 0.002], avoidance/numbing [0.513 (0.161, 0.864); p = 0.004] and hyperarousal [0.355 (0.051, 0.659); p = 0.022]. An increase in the total number of cardiac symptoms (score range 0-6) was also associated with an increase in total PTSD symptoms [0.343 (0.202, 0.484); p < 0.001]. Psychotherapy in the post-hospital period moderated the association between the change in heartbeat symptoms and the change in total PTSD symptoms [-0.813 (-1.553, -0.074); p = 0.031 for interaction]; the association between the onset of heart beat symptoms and an increase in total PTSD symptoms was weaker in patients who attended psychotherapy [0.437 (-0.178, 1.052); p = 0.16] than in those who did not [0.825 (0.341, 1.309); p < 0.001]. Conclusion Changes in cardiac symptoms between 3 and 12 months after hospitalization are associated with changes in ACS-induced PTSD symptoms. ClinicalTrials.gov #NCT01781247

Fluctuating diamagnetism in underdoped high temperature superconductors

The fluctuation induced diamagnetism of underdoped high temperature superconductors is studied in the framework of the Lawrence-Doniach model. By taking into account the fluctuations of the phase of the order parameter only, the latter reduces to a layered XY-model describing a liquid of vortices which can be either thermally excited or induced by the external magnetic field. The diamagnetic response is given by a current-current correlation function which is evaluated using the Coulomb gas analogy. Our results are then applied to recent measurements of fluctuation diamagnetism in underdoped YBCO. They allow to understand both the observed anomalous temperature dependence of the zero-field susceptibility and the two distinct regimes appearing in the magnetic field dependence of the magnetization.Comment: 12 pages, 4 figures included, accepted for publication in PR

Editorial Note

Social Ontology encompasses a wide variety of inquiries into the nature, structure and perhaps essence of social phenomena, and their role and place in our world. Topics of research in Social Ontology range from small-scale interactions to large-scale institutions, from spontaneous teamwork to the functioning of formal organizations, and from unintended consequences to institutional design. Social Ontology brings together theoretical work from a large number of disciplines. This rapidly evolving field of research has attracted increasing attention over the last couple of decades, and the conceptual tools recent research in Social Ontology has provided have proved to be useful in a large number of domains, such as the study of the evolution of communication, the structure of social norms, social structure, and social change, the nature of collective responsibility, and the status of corporate agents. The Journal of Social Ontology aims to further this research. It provides a forum of exchange between scholars of diverse disciplinary, scholarly, and methodological backgrounds, and invites submissions from all branches of Social Ontology. The Journal of Social Ontology adopts strict standards of selection and relies heavily on its carefully selected referees. In a world in which publication strategies and outlets are changing at a tremendous pace, it is difficult to say what the future of scholarly publication will look like. With a generous grant from the University of Vienna for the start-up phase, the Journal of Social Ontology now appears as an Open Access Journal with De Gruyter, thus combining professional support by an established publisher with unlimited accessibility. In addition, the Journal of Social Ontology has been founded together with the International Social Ontology Society (ISOS) that supports the work of this journal. We wish to express our thanks to our supporters, contributors, and referees; we hope that our joint effort will grant the work published in this journal the impact it deserves

Relativistic nature of a magnetoelectric modulus of Cr_2O_3-crystals: a new 4-dimensional pseudoscalar and its measurement

Earlier, the magnetoelectric effect of chromium sesquioxide Cr_2O_3 has been determined experimentally as a function of temperature. One measures the electric field-induced magnetization on Cr_2O_3 crystals or the magnetic field-induced polarization. From the magnetoelectric moduli of Cr_2O_3 we extract a 4-dimensional relativistic invariant pseudoscalar $\widetilde{\alpha}$. It is temperature dependent and of the order of 10^{-4}/Z_0, with Z_0 as vacuum impedance. We show that the new pseudoscalar is odd under parity transformation and odd under time inversion. Moreover, $\widetilde{\alpha}$ is for Cr_2O_3 what Tellegen's gyrator is for two port theory, the axion field for axion electrodynamics, and the PEMC (perfect electromagnetic conductor) for electrical engineering.Comment: Revtex, 36 pages, 9 figures (submitted in low resolution, better quality figures are available from the authors

Magnetodielectric Effects from Spin Fluctuations in Isostructural Ferromagnetic and Antiferromagnetic Systems

We report on the effects of spin fluctuations, magnetic ordering, and external magnetic field on the dielectric constant of the ferromagnet SeCuO3, and the antiferromagnet TeCuO3. A model based on the coupling between uniform polarization and the q-dependent spin-spin correlation function is presented to explain the different behaviors for these isostructural compounds. The large magnetocapacitance near the transition temperature in the ferromagnet SeCuO3 suggests routes to enhancing the magnetodielectric response for practical applications.Comment: 15 pages, 3 figure