70 research outputs found
Modeling Cities and Landscapes in 3D with CityGML
No full textCityGML is the most important international standard used to model cities and landscapes in 3D with extensive semantics. Compared to BIM standards such as IFC, CityGML models are usually less detailed but they cover a much greater spatial extent. They are also available in any of five standardized levels of detail. CityGML serves as an exchange format and as a data source for visualizations, either in dedicated applications or in a web browser. It can also be used for a wide range of spatial analyses, such as visibility studies and solar potential. Ongoing research will improve the integration of BIM standards with CityGML, making improved data exchange possible throughout the life-cycle of urban and environmental processes.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Urban Data Scienc
An Impact Study of the Economic Partnership Agreements (EPAs) in the Six ACP Regions
No full textThis article intends to present a very detailed analysis of the trade-related aspects of Economic Partnership Agreements (EPAs) negotiations. We use a dynamic partial equilibrium model – focusing on the demand side – at the HS6 level (covering 5,113 HS6 products). Two alternative lists of sensitive products are constructed, one giving priority to the agricultural sectors, the other focusing on tariff revenue preservation. In order to be WTO compatible, EPAs must translate into 90 percent of bilateral trade fully liberalised. We use this criterion to simulate EPAs for each negotiating regional block. ACP exports to the EU are forecast to be 10 percent higher with the EPAs than under the GSP/EBA option. On average ACP countries are forecast to lose 70 percent of tariff revenues on EU imports in the long run. Yet imports from other regions of the world will continue to provide tariff revenues. Thus when tariff revenue losses are computed on total ACP imports, losses are limited to 26 percent on average in the long run and even 19 percent when the product lists are optimised. The final impact on the economy depends on the importance of tariffs in government revenue and on potential compensatory effects. However this long term and less visible effect will mainly depend on the capacity of each ACP country to reorganise its fiscal base.Preferential Trade Agreements, Africa, EPAs, Partial Equilibrium Simulations, International Relations/Trade,
Molecular community surveillance of Plasmodium falciparum in 6 sites of different malaria endemicity in Tanzania
No full textMalaria prevalence estimates in Tanzania have been documented to decline in the recent years. National malaria data shows prevalence rates have been reduced by half from 18% in 2008 to 9% in 2012 (THMIS 2009; 2013). This decline has been attributed to countrywide implementation of malaria interventions, including indoor residual spraying (IRS), mass distribution of insecticide treated nets (ITNs), long-lasting ITNs and the use of artemisinin combination therapy (ACT), which aim at transmission reduction. Monitoring and evaluation of malaria interventions requires accurate information on the remaining malaria burden in the community. The rapid diagnostic tests (RDTs) and light microscopy (LM) are the commonly used diagnostic tools for parasite detection and estimation of parasite prevalence rates in many resource-limited areas such as Tanzania. However, owing to the low detection limit of LM and RDTs of about 50-100 parasites/µL, their ability to capture low density infections is limited (Moody 2002; MalEra 2011). The use of molecular techniques to detect malaria parasites has been advocated to improve the accuracy of parasite prevalence estimates, especially in moderate to low endemic settings. This is because in areas of reduced endemicity, most infections occur at low densities and cannot be detected by the routine diagnostic tools. With a detection limit of about 0.034 parasites/µL of blood, molecular diagnostics are more reliable for parasite detection. In Tanzania, most of the parasites prevalence estimates have been performed by LM and RDTs, hence the most of the low density infections may remain undetected. Thus this thesis aimed to assess the usefulness of diagnostic methods for epidemiological studies by comparing the performance of routine and molecular diagnostics in parasite and gametocytes detection in community samples from Tanzania. Furthermore, the thesis investigated the occurrence of submicroscopic infections at different endemic sites in Tanzania.
For the above aims we conducted community surveys at 6 sites in Tanzania between 2011 and 2013. These sites were classified as low (Iringa), low urban (Dar-Es Salaam), moderate (coastal Tanga and Lugoba) and high (Rufiji and Morogoro) endemic sites according to district prevalence data recorded by the Tanzania HIV and Malaria indicator surveys of 2008 (THMIS 2009): A total of 2046 volunteers of all ages with signed consent forms were recruited. Finger prick blood was drawn from all individuals for parasite detection by LM, RDT and 18S rRNA qPCR. Gametocytes were detected by both LM and qRT-PCR targeting transcripts of the gametocyte specific expressed marker pfs25.
Generally, high P. falciparum Prevalence rates of 20% (416/2046; 95% CI 18-22%) by 18S rRNA qPCR, 17% (349/2046; 95% CI 15.4-18.7%) by RDT and 11% (229/2046; 95% CI 9.8-12%) by LM were recorded in Tanzania. A substantial variation in molecular prevalence rates from geographically different sites was observed varying from 50% in the high endemic site, Rufiji, to 0.6% in the low endemic site, Iringa. These observed differences highlight the heterogeneity of transmission patterns in Tanzania attributed to geographical differences. Molecular parasite diagnostics unveiled that more than a half, 60% (249/416) of P. falciparum positive samples carried submicroscopic infections. Submicroscopic carriage was prevalent in all endemic settings. However, very few positive samples from areas of low and moderate endemicity impede a firm conclusion on the association of endemicity and submicroscopic carriage to be drawn from our samples. Molecularly determined Gametocyte prevalence was 15.3% (312/2046; 95% CI 13.6-16.8%) when data from all sites were combined. On the other hand, LM detected only 0.88% (18/2046; 95% CI 0.47-1.2%) of all samples implying only about 5% of the total gametocytes detected by molecular assay.
In conclusion molecular parasite detection revealed high parasite prevalence in Tanzania, such precise point prevalence molecular data obtained from community sampling may provide a more reliable basis of planning new tools of interventions or monitoring and evaluating the performance of existing tools in the country. Furthermore, high submicroscopic carriage of >50% in Tanzania, particularly in adults is key indicator of transmission potential of asymptomatic infections in Tanzania community and thus it is relevant for control strategies to focus on identifying submicroscopic carriers in order to successfully interrupt transmission
Sandwich sign of Borrmann type 4 gastric cancer on diffusion-weighted magnetic resonance imaging
No full textObjective: To assess the appearance of Borrmann type 4 (BT-4) gastric cancer on diffusion-weighted magnetic resonance imaging (DWI) and to investigate the potential of qualitative and quantitative DW images analysis to differentiate BT-4 gastric cancer from poorly distended normal stomach wall. Materials and methods: DWI was performed on 23 patients with BT-4 gastric cancer and 23 healthy volunteers. The signal characteristics and correlated histopathological basis of the cancers on DWI were investigated. The contrast-to-noise ratios (CNR) of cancer were compared between DWI and T1WI/T2WI. The thickness and apparent diffusion coefficient (ADC) of cancer and normal stomach wall were compared. Results: All of the gastric cancers displayed hyperintensity compared to the nearby normal gastric wall on DWI. A three-layer sandwich sign that demonstrated high signal intensity in the inner and outer layer, and low signal intensity in the intermediate layer was observed in 69.6% of cancers on DWI. The low signal intensity represents the muscularis propria through the comparison with pathology, and it is postulated that scattering distribution of the cancer cells in this layer causes less damage and subsequently less restriction of water movement, which causes the low signal intensity on DWI. The CNR obtained with DWI was higher than that with T1WI and T2WI (P < 0.001). The mean ADC value of BT-4 gastric cancer was significantly lower than the poorly distended normal stomach wall (1.12 +/- 0.23 x 10(-3) mm(2)/s vs. 1.93 +/- 0.22 x 10(-3) mm(2)/s, P < 0.01). Conclusion: DWI can highlight the signals of BT-4 gastric cancer which may present a characteristic three-layer sandwich sign, and ADC values are helpful in the discrimination of gastric cancer from poorly distended stomach wall. (C) 2011 Elsevier Ireland Ltd. All rights reserved.Radiology, Nuclear Medicine & Medical ImagingSCI(E)PubMed7ARTICLE102481-24868
Special Issue on Vehicular and Pedestrian Traffic Flow from Data to Models
No full textWe are happy to present this special issue of Transportmetrica A on “Vehicular and pedestrian flow: from data to models”. It bundles eight papers, which describe the ever progressing state-of-the-art in this field. The methods which become available to model and the data collection techniques do change this field rapidly, which makes it possible to more accurately describe traffic flows. We have six papers on pedestrian dynamics and two papers on car traffic dynamics.The first paper “Microscopic travel time analysis of bottleneck experiments” by Bukáček, Hrabák and Krbálek discusses the effect of queuing from the lowest level: they report on experiments they did on pedestrians passing a single bottleneck. This is the first step in the process from data to models.The second paper, by Handel and Borrmann, discusses the next step. Their paper “Service bottlenecks in pedestrian dynamics” compares the bottlenecks both in real-world and in computational models. They conclude that the feedback in the queuing system, increasing efficiency in high-demand situations, is essential.Where the first two papers are focused on a bottleneck, the next two add a network component. This covers a complexity which is typical for pedestrian models, being route choice, i.e. the planned path in complex spatial structures like cities, airports or museums. The third paper of the special issue is “A unified pedestrian routing model for graph-based navigation built on cognitive principles”, by Kielar, Biedermann, Kneidl and Borrmann. The paper presents a methodology to describe routing including spatial as well as social-cognitive aspect
Information containers providing deep linkage of drawings and BIM models
No full textIn current BIM standards and today's BIM practice, drawings and models are used side-by-side. While respecting the de-facto coexistence of models and drawings, the induced information redundancy results in challenges for proper information management. It is thus desirable to establish and maintain deep links between the model elements and the corresponding drawing elements, as this allows for bi-directional navigation across the model/drawing boundaries and enables accessing non-geometrie model information from the drawing. In addition, consistency checking and preservation become more reliable. The paper specifies the requirements and semantics of the linking mechanism and discusses different technical implementations. Major emphasis is placed on the concept of the Information Container as defined by ISO 21597 which allows to represent and exchange linked models in a vendor-neutral format, but alternative mechanisms are also investigated. The paper finishes with presenting a feasibility case study.Urban Data Scienc
用X 光在矽單晶的異常效應測量 X光的偏振化因子
No full text[[abstract]]利用X 光繞射儀解晶體結構時，為了求得更精確的Structure factor，經常在繞射儀
上加單色儀。
理論上，若X 光在單色儀上之Bragg 角為θM 時，由Kinematical theory，理想的mo
saic單色儀之偏振化比值為Cos22θM；若由Dynamical theory，理想的Perfect 單色
儀之偏振化比值為｜Cos2θM ｜。
本實驗利用完美矽單晶的Borrmann effect ，求得CuK2經石墨單色儀後之偏振化比值
為0.909 （4 ），接近於Perfect Crystal 之偏振化比值。
From GIS to BIM and back again – A spatial query language for 3D building models and 3D city models
No full textThe article presents the development of Spatial Query Language for 3D building and 3D city models. Inspired by the achievements of the GIS community in developing spatial query functionality for 2D space, the author adopted these concepts and applied them on geometric objects in 3D space. The developed query language provides metric (closer Than, farther Than, etc.), directional (above, below, northOf, etc.) and topological operators (touch, within, contain,etc.) for use in SQL statements. The operators have been implemented by algorithms which are based on the hierarchical space-partitioning data structure octree. The octree allows for the application of recursive algorithms that successively increase the discrete resolution of the spatial objects employed and thereby enables the user to trade off between computational effort and the required accuracy. Additionally, a fuzzy handling of spatial relationships becomes possible. The article describes the available spatial operators and the algorithms developed to implement them
On Coherence in Bragg-Primakoff Axion Photoconversion
No full textAxions and axion-like pseudoscalar particles with dimension-5 couplings to
photons exhibit coherent Bragg-Primakoff scattering with ordered crystals at
keV energy scales. This provides for a natural detection technique in searches
for axions produce in the Sun's interior. I will motivate the utility of dark
matter direct detection experiments in searching for solar axions, emphasizing
the role crystal-based detector technologies. I present an updated theoretical
treatment of the Bragg-Primakoff photoconversion process for keV pseudoscalars,
and address simultaneously the effects of absorption of final state photons in
crystals on the loss of coherence, which can lead to large suppressive
corrections to the event rate sensitivity for this detection technique.
However, I also show that the Borrmann effect of anomalous absorption
significantly lifts the suppression. This phenomenon is studied in Ge, NaI, and
CsI crystal experiments and its impact on the the projected sensitivities of
SuperCDMS, LEGEND, and SABRE to the solar axion parameter space. Lastly, I
investigate the future reach of multi-ton scale crystal detectors and discuss
strategies to maximize the discovery potential of experimental efforts in this
vein.Comment: PhD Thesis. 75 pages, 22 figures. arXiv admin note: substantial text
overlap with arXiv:2307.0486
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