Flexible Abstraction Layers for VR application development

The development of domain-specific Virtual Reality applications is often a slow and laborious process. The integration of the domain-specific functionality in an interactive Virtual Environment requires close collaboration between domain expert and VR developer, as well as the integration of domain-specific data and software in a VR application. The software environment needs to support the entire development process and software life cycle, from the early stages of iterative, rapid prototyping to a final end-user application. In this paper, we propose the use of flexible abstraction layers in the form of a dynamic scripting language, which act as the glue between VR system components and external software libraries and applications. First, we discuss the motivation and potential of our approach, after which we overview related approaches. Then, we describe the integration of a Python interpreter in our VR toolkit. The potential of our integration approach is demonstrated by rapid prototyping features, the flexible extension of core functionality and the integration of an external toolkit. We conclude with an overview of implications our approach has for the future development of new framework features and application integration

RayCursor: a 3D Pointing Facilitation Technique based on Raycasting

International audienceRaycasting is the most common target pointing technique in virtual reality environments. However, performance on small and distant targets is impacted by the accuracy of the pointing device and the user’s motor skills. Current point- ing facilitation techniques are currently only applied in the context of the virtual hand, i.e. for targets within reach. We propose enhancements to Raycasting: filtering the ray, and adding a controllable cursor on the ray to select the near- est target. We describe a series of studies for the design of the visual feedforward, filtering technique, as well as a comparative study between different 3D pointing techniques. Our results show that highlighting the nearest target is one of the most efficient visual feedforward technique. We also show that filtering the ray reduces error rate in a drastic way. Finally we show the benefits of RayCursor compared to Raycasting and another technique from the literature

Anti-thymocyte globulin with CsA and MMF as GVHD prophylaxis in nonmyeloablative HLA-mismatched allogeneic HCT

Nonmyeloablative regimens are used for allogeneic hematopoietic cell transplantation (HCT) of older or medically unfit patients, but successful outcome is still hindered by graft-versus-host disease (GVHD), especially in the setting of HLA-mismatched HCT. New GVHD prophylaxis strategies are emerging, including the triple drug strategy, that improve the GVHD-free and relapse-free survival (GRFS). Because the impact of ATG in HLA-mismatched Flu-TBI-based nonmyeloablative HCT has not been investigated, we did a retrospective analysis in three Dutch centers. 67 patients were evaluable, with a median age of 56 years. Overall survival, relapse-free survival and GRFS at 4 years were 52%, 43%, and 38%, respectively. NRM findings and cumulative incidence of relapse at 4 years were 26% and 31%, respectively. At 1-year grade II-IV had occurred in 40% of the patients, and the incidence of moderate-severe chronic GVHD incidence was 16%. Acknowledging the limitations of retrospective analyses, we conclude that the use of ATG for HLA-mismatched truly nonmyeloablative Flu-TBI HCT is feasible and results in acceptable long term outcomes, especially with regards to GRFS. We consider ATG in combination with cyclosporin and mycophenolate mofetil as an alternative for the triple drug strategy that uses sirolimus for GVHD prophylaxis in this particular setting

Outline Pursuits:Gaze-assisted Selection of Occluded Objects in Virtual Reality

In 3D environments, objects can be difficult to select when they overlap, as this affects available target area and increases selection ambiguity. We introduce Outline Pursuits which extends a primary pointing modality for gaze-assisted selection of occluded objects. Candidate targets within a pointing cone are presented with an outline that is traversed by a moving stimulus. This affords completion of the selection by gaze attention to the intended target's outline motion, detected by matching the user's smooth pursuit eye movement. We demonstrate two techniques implemented based on the concept, one with a controller as the primary pointer, and one in which Outline Pursuits are combined with head pointing for hands-free selection. Compared with conventional raycasting, the techniques require less movement for selection as users do not need to reposition themselves for a better line of sight, and selection time and accuracy are less affected when targets become highly occluded

Low relapse risk in poor risk AML after conditioning with 10-day decitabine, fludarabine and 2 Gray TBI prior to allogeneic hematopoietic cell transplantation.

Patients with poor risk acute myeloid leukemia (AML) have a dismal outcome. We hypothesized that combining decitabine with a standard non-myeloablative (NMA) conditioning regimen prior to allogeneic hematopoietic cell transplantation (allo HCT), might decrease the relapse incidence. We conducted a multicenter prospective phase II study (NCT02252107) with 10-day decitabine (20 mg/m(2)/day) integrated in a standard non-myeloablative conditioning regimen (3 days fludarabine 30 mg/m(2) with 2 Gray total body irradiation (TBI)). Patients with AML ≥ 18 years in 1st (in)complete remission (CR/CRi) with a poor or very poor risk profile, as defined by the HOVON-132 protocol, were eligible. Results: Forty-six patients (median age 60; range 23-74) were included. Median follow up time was 44 months (range 31-65 months). The cumulative 1-year incidence of relapse and NRM were respectively 23% and 11%. Incidence of grade III-IV acute graft-vs-host-disease (GVHD) and severe chronic GVHD were 13% and 20%, respectively. One-year OS was 70%. Application of ELN 2017 risk classification to the study cohort revealed a cumulative one-year relapse rate of respectively 31% and 13% for the adverse and intermediate risk patients. To conclude, the 10-day DEC/FLU/TBI conditioning regimen prior to allo HCT in poor risk AML patients is effective and feasible

Plasma and Liver Lipidomics Response to an Intervention of Rimonabant in ApoE*3Leiden.CETP Transgenic Mice

Background: Lipids are known to play crucial roles in the development of life-style related risk factors such as obesity, dyslipoproteinemia, hypertension and diabetes. The first selective cannabinoid-1 receptor blocker rimonabant, an anorectic anti-obesity drug, was frequently used in conjunction with diet and exercise for patients with a body mass index greater than 30 kg/m2 with associated risk factors such as type II diabetes and dyslipidaemia in the past. Less is known about the impact of this drug on the regulation of lipid metabolism in plasma and liver in the early stage of obesity. Methodology/Principal Findings: We designed a four-week parallel controlled intervention on apolipoprotein E3 Leiden cholesteryl ester transfer protein (ApoE&z.ast;3Leiden.CETP) transgenic mice with mild overweight and hypercholesterolemia. A liquid chromatography-linear ion trap-Fourier transform ion cyclotron resonance-mass spectrometric approach was employed to investigate plasma and liver lipid responses to the rimonabant intervention. Rimonabant was found to induce a significant body weight loss (9.4%, p<0.05) and a significant plasma total cholesterol reduction (24%, p<0.05). Six plasma and three liver lipids in ApoE&z.ast;3Leiden.CETP transgenic mice were detected to most significantly respond to rimonabant treatment. Distinct lipid patterns between the mice were observed for both plasma and liver samples in rimonabant treatment vs. non-treated controls. This study successfully applied, for the first time, systems biology based lipidomics approaches to evaluate treatment effects of rimonabant in the early stage of obesity. Conclusion: The effects of rimonabant on lipid metabolism and body weight reduction in the early stage obesity were shown to be moderate in ApoE&z.ast;3Leiden.CETP mice on high-fat diet. © 2011 Hu et al

Aging of hematopoietic stem cells:Intrinsic changes or micro-environmental effects?

During development hematopoietic stem cells (HSCs) expand in number and persist throughout life by undergoing self-renewing divisions. Nevertheless, the hematopoietic system does not escape the negative effects of aging, suggesting that self-renewal is not complete. A fundamental issue in stem cell biology relates to such age-dependent loss of stem cell activity. Both stem cell intrinsic factors and extrinsic factors associated with an aging micro-environment could contribute to aging of the hematopoietic system. Recently, changes in the clonal composition of the HSC compartment during aging have been put forward as a key factor. Here, we discuss these recent developments and speculate how they may be of clinical relevance