The Herschel/PACS view of disks around low-mass stars in Chamaleon-I

Circumstellar disks are expected to be the birthplaces of planets. The potential for forming one or more planets of various masses is essentially driven by the initial mass of the disks. We present and analyze Herschel/PACS observations of disk-bearing M-type stars that belong to the young ~2 Myr old Chamaleon-I star forming region. We used the radiative transfer code RADMC to successfully model the SED of 17 M-type stars detected at PACS wavelengths. We first discuss the relatively low detection rates of M5 and later spectral type stars with respect to the PACS sensitivity, and argue their disks masses, or flaring indices, are likely to be low. For M0 to M3 stars, we find a relatively broad range of disk masses, scale heights, and flaring indices. Via a parametrization of dust stratification, we can reproduce the peak fluxes of the 10 $\mu$m emission feature observed with Spitzer/IRS, and find that disks around M-type stars may display signs of dust sedimentation. The Herschel/PACS observations of low-mass stars in Cha-I provide new constraints on their disk properties, overall suggesting that disk parameters for early M-type stars are comparable to those for more massive stars (e.g., comparable scale height and flaring angles). However, regions of the disks emitting at about 100 $\mu$m may still be in the optically thick regime, preventing direct determination of disk masses. Thus the modeled disk masses should be considered as lower limits. Still, we are able to extend the wavelength coverage of SED models and start characterizing effects such as dust sedimentation, an effort leading the way towards ALMA observations of these low-mass stars

Cross-Sector Partnerships and the Co-creation of Dynamic Capabilities for Stakeholder Orientation

This is the final version of the article. Available from Springer Verlag via the DOI in this record.This paper explores the relationship between business experience in cross-sector partnerships (CSPs) and the co-creation of what we refer to as ‘dynamic capabilities for stakeholder orientation,’ consisting of the four dimensions of (1) sensing, (2) interacting with, (3) learning from and (4) changing based on stakeholders. We argue that the co-creation of dynamic capabilities for stakeholder orientation is crucial for CSPs to create societal impact, as stakeholder-oriented organizations are more suited to deal with “wicked problems,” i.e., problems that are large, messy, and complex (Rittel and Webber, Policy Sciences 4:155–169, 1973; Waddock, Paper presented at the 3rd international symposium on cross sector social interactions, 2012). By means of a grounded theory approach of inductive research, we collected and interpreted data on four global agri-food companies which have heterogeneous experience in participating in CSPs. The results of this paper highlight that only companies’ capability of interacting with stakeholders continually increases, while their capabilities of sensing, learning from, and changing based on stakeholders first increase and then decrease as companies gain more experience in CSP participation. To a large extent, this can be attributed to the development of corporate strategies on sustainability after a few years of CSP participation, which entails a shift from a reactive to a proactive attitude towards sustainability issues and which may decrease the need or motivation for stakeholder orientation. These findings open up important issues for discussion and for future research on the impact of CSPs in a context of wicked problems

Modifying the Response of Male Broiler Chickens to Heat Stress Through Early Age Feed Restriction and Thermal Conditioning

Two experiments were conducted to investigate the effects of early age feed restriction and heat conditioning on tolerance to acute and chronic heat stress in male broiler chickens. In both experiments, equal numbers of chickens were subjected to (i) 60% feed restriction on day 4, 5, and 6 (FR), (ii) exposure to 36±IoC and 50-60% relative humidity for 1 hour from day 1 to 21 (HT), (iii) 60% feed restriction on day 4, 5, and 6 and exposure to 36± l oC and 50-60% relative humidity for 1 hour from day 1 to 21 (FRHT). (iv) ad libitum feeding and no heat treatment (control). In experiment I, on day 35, all birds were exposed to 39± l oC for 6 hours and 50% relative humidity. Subjecting chicks to FR, HT and FRHT reduced HLR response to the heat challenge. Following heat exposure, the FR and FRHT chick had greater heat shock protein (hsp) 70 density than those of controls. The hsp 70 response of HT birds was not significantly different from the other three groups. The FRHT birds were more hyperthermic than controls during heat challenge. In experiment II, from day 36- 50, all birds were exposed to 38± l oC and 80 % relative humidity for 2 hours/day. One day following heat exposure (day 37), all birds were administrated intranasally with infectious bursal disease (IBD) vaccine virus. The dosage used was l Ox of the recommended level. Subjecting chicks to FRHT improved relative weight gain and resistance to IBD infection and reduced HLR in response to the heat treatment as compared with the control birds. Although there is evidence that FR and HT can improve heat tolerance, the FRHT combination may further enhance the ability of birds to withstand chronic heat stress. The acquired improved heat tolerance resulting from FRHT, FR, and HT could be attributed to enhanced hsp 70 response. The trend of hsp 70 response correlated well with IBD lesion scores, suggesting hsp 70 may play a role in resistance against viral infection. Based on experiment I and II, it can be concluded that the present findings confirmed earlier studies that FR is effective in alleviating the adverse effects of heat stress. Subjecting birds to FRHT can further improve tolerance to chronic but not acute heat stress

The First Detailed Look at a Brown Dwarf Disk

The combination of mid-infrared and recent submm/mm measurements allows us to set up the first comprehensive spectral energy distribution (SED) of the circumstellar material around a young Brown Dwarf. Simple arguments suggest that the dust is distributed in the form of a disk. We compare basic models to explore the disk parameters. The modeling shows that a flat disk geometry fits well the observations. A flared disk explains the SED only if it has a puffed-up inner rim and an inner gap much larger than the dust sublimation radius. Similarities and differences with disks around T Tauri stars are discussed.Comment: 11 pages, 1 figur

Volumetric data analysis using Morse-Smale complexes

The 3D Morse-Smale complex is a fundamental topological construct that partitions the domain of a real-valued function into regions having uniform gradient flow behavior. In this paper, we consider the construction and selective presentation of cells of the Morse-Smale complex and their use in the analysis and visualization of scientific datasets. We take advantage of the fact that cells of different dimension often characterize different types of features present in the data. For example, critical points pinpoint changes in topology by showing where components of the level sets are created, destroyed or modified in genus. Edges of the Morse-Smale complex extract filament-like features that are not explicitly modeled in the original data. Interactive selection and rendering of portions of the Morse-Smale complex introduces fundamental data management challenges due to the unstructured nature of the complex even for structured inputs. We describe a data structure that stores the Morse-Smale complex and allows efficient selective traversal of regions of interest. Finally, we illustrate the practical use of this approach by applying it to cryo-electron microscopy data of protein molecules

Direct Multifield Volume Ray Casting of Fiber Surfaces

Multifield data are common in visualization. However, reducing these data to comprehensible geometry is a challenging problem. Fiber surfaces, an analogy of isosurfaces to bivariate volume data, are a promising new mechanism for understanding multifield volumes. In this work, we explore direct ray casting of fiber surfaces from volume data without any explicit geometry extraction. We sample directly along rays in domain space, and perform geometric tests in range space where fibers are defined, using a signed distance field derived from the control polygons. Our method requires little preprocess, and enables real-time exploration of data, dynamic modification and pixel-exact rendering of fiber surfaces, and support for higher-order interpolation in domain space. We demonstrate this approach on several bivariate datasets, including analysis of multi-field combustion data

Apoptotic cell death in canine hair follicle

Apoptotic cell death is an essential homeostatic mechanism involved in the control of cellular turnover in a variety of adult tissues. Cytoplasmic and nuclear condensation morphologically define this process whose biochemical hallmark is extensive DNA fragmentation into discrete oligonucleosomic units. Hair follicle growth and regression has been shown to be correlated with apoptosis in humans, mice, rats and guinea pigs. The present study was carried out to evaluate its implication in canine hair biology in order to define the spatio-temporal relationship between apoptosis and the hair cycle in dogs. As assessed by terminal deoxy-nucleotidyl transferase-mediated d-UTP nick-end-labelling (TUNEL) and by basic histological and ultrastructural assays, apoptotic cells appeared both in the growing and in the regressing follicle epithelium showing the well characterized morphological features described in the previous relevant literature