A virtual place of memory: Virtual reality as a method for communicating conflicted heritage at Camp Westerbork

An important goal of the project Accessing Campscapes: inclusive strategies for using European Conflicted Heritage (iC-ACCESS), has been to develop inclusive approaches for the presentation and communication of contending perspectives on Nazi and Stalinist sites (Dolghin et al. 2017). A key objective for treating these 'heritagescapes' has been to 'develop state-of-the-art strategies and implement innovative tools which provide sustainable in-situ and virtual forms of investigation, presentation and representation' (Van der Laarse 2020). A central issue which is gaining increasing attention in heritage studies and management is the dilemma of preserving and exhibiting material remnants of Wehrmacht and SS-barracks or residencies at Holocaust memorial camps which are generally framed as victimhood sites. The Commander's house at Herinneringscentrum Westerbork is a case in point and can be placed in different perspectives on the history of the camp terrain and all related sensibilities on its meaning as an object of heritage. In order to realise an application that can accommodate these perspectives, iC-ACCESS project leader Prof. dr. R. van der Laarse contracted two laboratories specialised consecutively in 3D visualisation technologies and spatial information to cooperate on its development, the 4D Research Lab (University of Amsterdam, The Netherlands) and the SPINlab (Vrije Universiteit Amsterdam). This paper illustrates the ideas, discussions and choices related to the production of the 'Campscapes – Westerbork Commander's House App', provides a concise technical description of the actual application and presents a short prospection on potential future developments

Describing and measuring leadership within school teams by applying a social network perspective

Despite the growing number of studies that acknowledge a crucial role of distributed leadership within schools, limited knowledge exists on how to describe and measure this multi-faceted concept. In a social network study with 130 respondents, from 14 Dutch school teams carrying out collaborative innovation, we theoretically describe three core aspects of the social interaction process of distributed leadership: collective, dynamic, or relational. Furthermore, we empirically explore how to measure all these three aspects of distributed leadership from a social network perspective, whereas most research focuses on either collective or dynamic. Our findings indicate that three network measures (density, reciprocity, indegree centralization) form a coherent combination to measure distributed leadership in school teams in terms of collective, relational, and dynamic, respectively. Furthermore, based on the combination of measures we found differences in distributed leadership between school teams. Thus, adding the relational aspect in addition to the collective and dynamic aspects seems to be informative to measure distributed leadership. Our study motivates to take a social network perspective, instead of the mostly used aggregation approaches, to measure distributed leadership in school teams

The galaxy environment in GAMA G3C groups using the Kilo Degree Survey Data Release 3

We aim to investigate the galaxy environment in GAMA Galaxy Groups Catalogue (G3C) using a volume-limited galaxy sample from the Kilo Degree Survey Data Release 3. The k-Nearest Neighbour technique is adapted to take into account the probability density functions (PDFs) of photometric redshifts in our calculations. This algorithm was tested on simulated KiDS tiles, showing its capability of recovering the relation between galaxy colour, luminosity and local environment. The characterization of the galaxy environment in G3C groups shows systematically steeper density contrasts for more massive groups. The red galaxy fraction gradients in these groups is evident for most of group mass bins. The density contrast of red galaxies is systematically higher at group centers when compared to blue galaxy ones. In addition, distinct group center definitions are used to show that our results are insensitive to center definitions. These results confirm the galaxy evolution scenario which environmental mechanisms are responsible for a slow quenching process as galaxies fall into groups and clusters, resulting in a smooth observed colour gradients in galaxy systems.Comment: 14 pages, Accepted to MNRA

The black hole in IC 1459 from HST observations of the ionized gas disk

The peculiar elliptical galaxy IC 1459 (M_V = -21.19, D = 16.5 Mpc) has a fast counterrotating stellar core, stellar shells and ripples, a blue nuclear point source and strong radio core emission. We present results of a detailed HST study of IC 1459, and in particular its central gas disk, aimed a constraining the central mass distribution. We obtained WFPC2 narrow-band imaging centered on the Halpha+[NII] emission lines to determine the flux distribution of the gas emission at small radii, and we obtained FOS spectra at six aperture positions along the major axis to sample the gas kinematics. We construct different dynamical models for the Halpha+[NII] and Hbeta kinematics that include a supermassive black hole, and in which the stellar mass distribution is constrained by the observed surface brightness distribution and ground-based stellar kinematics. All models are consistent with a black hole mass in the range Mbh=1-4 x 10^8 Msun, and models without a black hole are always ruled out at high confidence.Comment: 40 pages including 14 figures, Latex; submitted to A

The counterrotating core and the black hole mass of IC1459

The E3 giant elliptical galaxy IC1459 is the prototypical galaxy with a fast counterrotating stellar core. We obtained one HST/STIS long-slit spectrum along the major axis of this galaxy and CTIO spectra along five position angles. We present self-consistent three-integral axisymmetric models of the stellar kinematics, obtained with Schwarzschild's numerical orbit superposition method. We study the dynamics of the kinematically decoupled core (KDC) in IC1459 and we find it consists of stars that are well-separated from the rest of the galaxy in phase space. The stars in the KDC counterrotate in a disk on orbits that are close to circular. We estimate that the KDC mass is ~0.5% of the total galaxy mass or ~3*10^9 Msun. We estimate the central black hole mass M_BH of IC1459 independently from both its stellar and its gaseous kinematics. Some complications probably explain why we find rather discrepant BH masses with the different methods. The stellar kinematics suggest that M_BH = (2.6 +/- 1.1)*10^9 Msun (3 sigma error). The gas kinematics suggests that M_BH ~ 3.5*10^8 Msun if the gas is assumed to rotate at the circular velocity in a thin disk. If the observed velocity dispersion of the gas is assumed to be gravitational, then M_BH could be as high as ~1.0*10^9 Msun. These different estimates bracket the value M_BH = (1.1 +/- 0.3)*10^9 Msun predicted by the M_BH-sigma relation. It will be an important goal for future studies to assess the reliability of black hole mass determinations with either technique. This is essential if one wants to interpret the correlation between the BH mass and other global galaxy parameters (e.g. velocity dispersion) and in particular the scatter in these correlations (believed to be only ~0.3 dex). [Abridged]Comment: 51 pages, LaTeX with 19 PostScript figures. Revised version, with three new figures and data tables. To appear in The Astrophysical Journal, 578, 2002 October 2

Virtual 3D planning of tracheostomy placement and clinical applicability of 3D cannula design:A three-step study

AIM: We aimed to investigate the potential of 3D virtual planning of tracheostomy tube placement and 3D cannula design to prevent tracheostomy complications due to inadequate cannula position. MATERIALS AND METHODS: 3D models of commercially available cannula were positioned in 3D models of the airway. In study (1), a cohort that underwent tracheostomy between 2013 and 2015 was selected (n = 26). The cannula was virtually placed in the airway in the pre-operative CT scan and its position was compared to the cannula position on post-operative CT scans. In study (2), a cohort with neuromuscular disease (n = 14) was analyzed. Virtual cannula placing was performed in CT scans and tested if problems could be anticipated. Finally (3), for a patient with Duchenne muscular dystrophy and complications of conventional tracheostomy cannula, a patient-specific cannula was 3D designed, fabricated, and placed. RESULTS: (1) The 3D planned and post-operative tracheostomy position differed significantly. (2) Three groups of patients were identified: (A) normal anatomy; (B) abnormal anatomy, commercially available cannula fits; and (C) abnormal anatomy, custom-made cannula, may be necessary. (3) The position of the custom-designed cannula was optimal and the trachea healed. CONCLUSIONS: Virtual planning of the tracheostomy did not correlate with actual cannula position. Identifying patients with abnormal airway anatomy in whom commercially available cannula cannot be optimally positioned is advantageous. Patient-specific cannula design based on 3D virtualization of the airway was beneficial in a patient with abnormal airway anatomy

A comparison of the Thunderbeat and standard electrocautery devices in head and neck surgery:a prospective randomized controlled trial

PURPOSE: New energy-based sutureless vessel ligation devices, such as the Thunderbeat (Olympus Medical Systems Corp., Tokyo, Japan), could reduce operative time and limit blood loss in head and neck surgery; however, efficacy and safety in major head and neck surgery have not been investigated in a prospective, randomized study. METHODS: This prospective, double-arm, randomized controlled trial consisted of two parts: total laryngectomy (TL) and neck dissection (ND). Thirty patients planned for TL were randomized in two groups. For the ND part, forty-two operative sides were likewise randomized. In both parts, Thunderbeat was used in addition to the standard instrumentation in the intervention groups, while only standard instrumentation was used in the control groups. Primary outcome values were blood loss, operative time and complication rate. RESULTS: For the TL part there was no difference in mean blood loss (p = 0.062), operative time (p = 0.512) and complications (p = 0.662) between both hemostatic techniques. For the neck dissection part, there was a reduction in blood loss (mean 210 mL versus 431 mL, p = 0.046) and in operative time (median 101 (IQR 85-130) minutes versus 150 (IQR 130-199) minutes, p = 0.014) when Thunderbeat was used. There was no difference in complication rate between both hemostatic systems (p = 0.261). CONCLUSION: The Thunderbeat hemostatic device significantly reduces operative blood loss and operative time for neck dissections, without increase in complications. In TL, blood loss using Thunderbeat was comparable with the standard technique, but the operative time tended to be shorter. TRIAL REGISTRATION: UMCG Research Register, Reg. no. 201700041, date of registration: 18/1/2017

N=2 supergravity in five dimensions revisited

We construct matter-coupled N=2 supergravity in five dimensions, using the superconformal approach. For the matter sector we take an arbitrary number of vector-, tensor- and hyper-multiplets. By allowing off-diagonal vector-tensor couplings we find more general results than currently known in the literature. Our results provide the appropriate starting point for a systematic search for BPS solutions, and for applications of M-theory compactifications on Calabi-Yau manifolds with fluxes.Comment: 35 pages; v.2: A sign changed in a bilinear fermion term in (5.7