Modelling clumpy PDRs in 3D - Understanding the Orion Bar stratification

Context. Models of photon-dominated regions (PDRs) still fail to fully reproduce some of the observed properties, in particular the combination of the intensities of different PDR cooling lines together with the chemical stratification, as observed e.g. for the Orion Bar PDR. Aims. We aim to construct a numerical PDR model, KOSMA-\tau 3D, to simulate full spectral cubes of line emission from arbitrary PDRs in three dimensions (3D). The model is to reproduce the intensity of the main cooling lines from the Orion Bar PDR and the observed layered structure of the different transitions. Methods. We build up a 3D compound, made of voxels ("3D pixels") that contain a discrete mass distribution of spherical "clumpy" structures, approximating the fractal ISM. To analyse each individual clump the new code is combined with the KOSMA-\tau PDR model. Probabilistic algorithms are used to calculate the local FUV flux for each voxel as well as the voxel-averaged line emissivities and optical depths, based on the properties of the individual clumps. Finally, the computation of the radiative transfer through the compound provides full spectral cubes. To test the new model we try to simulate the structure of the Orion Bar PDR and compare the results to observations from HIFI/Herschel and from the Caltech Submillimetre Observatory (CSO). In this context new Herschel data from the HEXOS guaranteed-time key program is presented. Results. Our model is able to reproduce the line integrated intensities within a factor 2.5 and the observed stratification pattern within 0.016 pc for the [Cii] 158 \mu m and different 12/13 CO and HCO+ transitions, based on the representation of the Orion Bar PDR by a clumpy edge-on cavity wall. In the cavity wall, a large fraction of the total mass needs to be contained in clumps. The mass of the interclump medium is constrained by the FUV penetration. Furthermore, ...Comment: Major changes compared to v1. Also several references have been adde

(M-theory-)Killing spinors on symmetric spaces

We show how the theory of invariant principal bundle connections for reductive homogeneous spaces can be applied to determine the holonomy of generalised Killing spinor covariant derivatives of the form $D= \nabla + \Omega$ in a purely algebraic and algorithmic way, where $\Omega : TM \rightarrow \Lambda^*(TM)$ is a left-invariant homomorphism. Specialising this to the case of symmetric M-theory backgrounds (i.e. $(M,g,F)$ with $(M,g)$ a symmetric space and $F$ an invariant closed 4-form), we derive several criteria for such a background to preserve some supersymmetry and consequently find all supersymmetric symmetric M-theory backgrounds.Comment: Updated abstract for clarity. Added missing geometries to section 6. Main result stand

Splitting the Hive

Warming late spring temperatures mark the beginning of swarm season in Utah, especially for beehives that have successfully overwintered. Swarming is when bees naturally divide the existing colony roughly in half, with half the bees remaining in the hive and the other half leaving (with the queen) to look for new accommodations. Colonies that swarm are often left with limited resources, do not produce much honey, and can be rendered too weak to overwinter. Splitting your hives in anticipation of swarming can help reduce the negative effects of swarming, giving bees a chance to build up resources and strength before the next winter. This fact sheet explains how to split hives, which is a better alternative than swarming that can prove detrimental to colony strength and longevity

Thriving Hives, Beekeeping Monthly Calendar

This calendar was created in an effort to simplify and make beekeeping easier to understand and learn for the beginning beekeeper. The calendar offers a broad understanding of what is happening in the hive in addition to guidelines for basic beekeeping tasks on a monthly basis. The calendar also provides users with lists of in-bloom plants to look for in the landscape as the beekeeping season progresses. This can help beekeepers assess resources available for the bees in the landscape. In addition to the monthly tasks, suggested recipes for some of the feeding supplements and treatments mentioned in the calendar are included to aid the beekeeper in implementation of these tasks

Setting Up Your Hive and Installing Bees

Getting your hive set up and your bees installed is an exciting first step for a beekeeper. However, it can also be a confusing and anxious time if it is your first experience. As there are many different methods for installing bees, this fact sheet provides a guide for the first time beekeeper. As you become more comfortable and experienced with your bees, you may modify these recommendations and methods to you own preferences

Evaluating the impact of road infrastructure on household income in Papua New Guinea:Spatial data compilation and analysis

As part of the ADB sub‐project ‘Developing Impact Evaluation Methodologies, Approaches, and Capacities in Selected Developing Member Countries’ two closely related research projects were carried out by VU to evaluate the impact of road infrastructure on household income in Papua New Guinea. One project focused on econometric analysis (contract no. 117629‐S85196), while the other developed the spatial database needed for this analysis (contract no. 117642‐S84962). The current report documents the data collection process and provides a concise description of the data that were collected for the project and the analyses that were performed to enrich the available data sources to create meaningful variables for the statistical analysis. It serves as a background document with the scientific paper‐that concisely describes the findings of the two joint research projects

Blueprint for Planning a Successful Program

Discusses program planning for librarians whose experience in this area is limited. How to plan and coordinate the program; Dealing with details; What to do on the day of the event; Ways to follow up; The program packet and what to include