Internet performance modeling: the state of the art at the turn of the century

Seemingly overnight, the Internet has gone from an academic experiment to a worldwide information matrix. Along the way, computer scientists have come to realize that understanding the performance of the Internet is a remarkably challenging and subtle problem. This challenge is all the more important because of the increasingly significant role the Internet has come to play in society. To take stock of the field of Internet performance modeling, the authors organized a workshop at Schloß Dagstuhl. This paper summarizes the results of discussions, both plenary and in small groups, that took place during the four-day workshop. It identifies successes, points to areas where more work is needed, and poses “Grand Challenges” for the performance evaluation community with respect to the Internet

A geological 3D-model of Austria

GeoSphere Austria (formerly Geologische Bundesanstalt - Geological Survey of Austria) has produced a supra-regional 3D framework model called “3D AUSTRIA” providing a large-scale geological overview for professional geologists, students and the public. This model is intended to act as support for subsequent regional modelling projects as well as for educational and communicational purpose. The modelled domain of covers a rectangular area of 175 000 km² including the national borders of Austria, down to a depth to 60 km below sea level. Model units are defined following the nomenclature of Schmid et al. (2004) and Froitzheim et al. (2008), each unit having a specific paleo-geographic origin and tectono-metamorphic history. Seven modelling units are considered: two continental plates (1) the Adriatic Plate, (2) the Eurasian Plate, four units from the Alpine orogenic wedge (3) the South-Alpine Superunit, (4) the Austroalpine Superunit, (5) the Penninic Superunit, (6) the Sub-Penninic Superunit and (7) Neogene sedimentary basins in the foreland and within the Alps. Due to the large-scale character of the model, relatively small constituents of the Alpine Orogen are merged together (Meliata Superunit and Inner Western Carpathian Superunit with the Austroalpine Superunit, Helvetic Superunit and Allochtone Molasse with the Sup-Penninic Superunit, intrusive rocks along the Periadriatic Fault with their host unit, minor Neogene basins with the Austroalpine Superunit). The model geometry is constrained by the geological map of Austria 1:1.5M (Schuster et al., 2019), (2) 24 published cross sections and (3) published contour maps for the Moho discontinuity (Ziegler & Dèzes, 2006) and the large Neogene basins. It has been generated with the SKUA-GOCAD software suite following the workflow of Pfleiderer et al. (2016). The framework model 3D AUSTRIA can be visualized with the web 3D Viewer of Geosphere Austria (https://gis.geosphere.at/portal/home/webscene/viewer.html?webscene=c11cd25795294ba8b6f276ab2d072afb) or downloaded from the Tethys Research Data Repository (https://doi.tethys.at/10.24341/tethys.184) allowing the generation of a physical multi-part model using 3D printing technology. It provides a unique way to comprehend the fundamentally 3D nature of sedimentary and tectonic features, like the unconformity at the base of Neogene sedimentary basins, the Alpine frontal thrust or the Tauern Window. The data acquired in the framework of the AlpArray project can be used in future for refining the geometry of 3D AUSTRIA

Evaluation of an Accounting Model for Dynamic Virtual Organizations

Accounting of Grid resource and service usage determines the central support activity for Grid systems to be adopted as a means for service-oriented computing in Dynamic Virtual Organizations (DVO). An all-embracing study of existing Grid accounting systems has revealed that these approaches focus primarily on technical precision, while they lack a foundation of appropriate economic accounting principles and the support for multi-provider scenarios or virtualization concepts. Consequently, a new, flexible, resource-based accounting model for DVOs was developed, combining technical and economic accounting by means of Activity-based Costing. Driven by a functional evaluation, this paper pursues a full-fledged evaluation of the new, generically applicable Grid accounting model. This is done for the specific environment of the Leibniz Supercomputing Centre (LRZ) in Garching, Germany. Thus, a detailed evaluation methodology and evaluation environment is outlined, leading to actual model-based cost calculations for a defined set of considered Grid services. The results gained are analyzed and respective conclusions on model applicability, optimizations, and further extensions are draw

Diagnosing and mapping pulmonary emphysema on X-ray projection images

To assess whether grating-based X-ray dark-field imaging can increase the sensitivity of X-ray projection images in the diagnosis of pulmonary emphysema and allow for a more accurate assessment of emphysema distribution. Lungs from three mice with pulmonary emphysema and three healthy mice were imaged ex vivo using a laser-driven compact synchrotron X-ray source. Median signal intensities of transmission (T), dark-field (V) and a combined parameter (normalized scatter) were compared between emphysema and control group. To determine the diagnostic value of each parameter in differentiating between healthy and emphysematous lung tissue, a receiver-operating-characteristic (ROC) curve analysis was performed both on a per-pixel and a per-individual basis. Parametric maps of emphysema distribution were generated using transmission, dark-field and normalized scatter signal and correlated with histopathology. Transmission values relative to water were higher for emphysematous lungs than for control lungs (1.11 vs. 1.06, p<0.001). There was no difference in median dark-field signal intensities between both groups (0.66 vs. 0.66). Median normalized scatter was significantly lower in the emphysematous lungs compared to controls (4.9 vs. 10.8, p<0.001), and was the best parameter for differentiation of healthy vs. emphysematous lung tissue. In a per-pixel analysis, the area under the ROC curve (AUC) for the normalized scatter value was significantly higher than for transmission (0.86 vs. 0.78, p<0.001) and dark-field value (0.86 vs. 0.52, p<0.001) alone. Normalized scatter showed very high sensitivity for a wide range of specificity values (94% sensitivity at 75% specificity). Using the normalized scatter signal to display the regional distribution of emphysema provides color-coded parametric maps, which show the best correlation with histopathology. In a murine model, the complementary information provided by X-ray transmission and dark-field images adds incremental diagnostic value in detecting pulmonary emphysema and visualizing its regional distribution as compared to conventional X-ray projections

From Driver to Supervisor: Comparing Cognitive Load and EEG-based Attentional Resource Allocation across Automation Levels

With increasing automation, drivers' roles transition from active operators to passive system supervisors, affecting their behaviour and cognitive processes. This study addresses the attentional resource allocation and subjective cognitive load during manual, SAE Level 2, and SAE Level 3 driving in a realistic environment. An experiment was conducted on a test track with 30 participants using a prototype automated vehicle. While driving, participants were subjected to a passive auditory oddball task and their electroencephalogram was recorded. The study analysed the amplitude of the P3a event-related potential component elicited by novel environmental stimuli, an objective measure of attentional resource allocation. The subjective cognitive load was assessed using the NASA Task Load Index. Results showed no significant difference in subjective cognitive load between manual and Level 2 driving, but a decrease in subjective cognitive load in Level 3 driving. The P3a amplitude was highest during manual driving, indicating increased attentional resource allocation to environmental sounds compared to Level 2 and Level 3 driving. This may suggest that during automated driving, drivers allocate fewer attentional resources to processing environmental information. It remains unclear whether the decreased processing of environmental stimuli in automated driving is due to top-down attention control (leading to attention withdrawal) or bottom-up competition for resources induced by cognitive load. This study provides novel empirical evidence on resource allocation and subjective cognitive load in automated driving. The findings highlight the importance of managing drivers' attention and cognitive load with implications for enhancing automation safety and the design of user interfaces.Comment: 17 pages, 4 figure

Cellular uptake and lysosomal delivery of galactocerebrosidase tagged with the HIV Tat protein transduction domain

A number of studies have shown that a short peptide, the protein transduction domain (PTD) derived from the HIV-1 Tat protein (Tat-PTD) improved cellular uptake in vitro and distribution in vivo of recombinant proteins bearing such PTDs when administered systemically. To investigate the effects of Tat-PTD addition on the subcellular localization of the lysosomal enzyme galactocerebrosidase (GALC, EC 3.2.2.46) and with a view towards designing improved therapeutic strategies for Krabbe disease (globoid cell leukodystrophy), mouse GALC was tagged C-terminally with the Tat-PTD. Compared with unmodified GALC, GALC bearing a Tat-PTD, a myc epitope and 6 consecutive His residues [GALC-TMH (Tat-PTD, a myc epitope and 6 consecutive His residues)] was found to be secreted more efficiently. Also, GALC-TMH was found to be taken up by cells both via mannose-6-phosphate receptor (M6PR)-mediated endocytosis as well as by M6PR-independent mechanisms. GALC-TMH displayed increased M6PR-independent uptake in fibroblasts derived from twitcher mice (a murine model of globoid cell leukodystrophy) and in neurons derived from the mouse brain cortex compared with GALC lacking a Tat-PTD. Immunocytochemical analyses revealed that Tat-modified GALC protein co-localized in part with the lysosome-associated membrane protein-1. Complete correction of galactosylceramide accumulation was achieved in twitcher mouse fibroblasts lacking GALC activity following addition of GALC-TMH. Therefore, GALC-TMH not only maintained the features of the native GALC protein including enzymatic function, intracellular transport and location, but also displayed more efficient cellular uptake. © 2007 The Authors

Stereoselective rearrangement of guaianolides to tricyclic δ-valerolactones

An unprecedented, highly stereoselective rearrangement of guaianolides, bearing a double bond at the C-6/C-6a position, to tricyclic δ-valerolactones is described