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- Althoff, Karin, 1974
(författare)
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Segmentation and Tracking Algorithms for in Vitro Cell Migration Analysis
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes a system for automatic in vitro cell migration analysis. Image sequences of adult neural stem/progenitor cells were acquired using a time-lapse bright-field microscopy setup. The adult neural stem/progenitor cell has the ability to differentiate into three different neural lineages; neuronal, astrocytic and oligodendrocytic. Different image analysis techniques were investigated for segmenting the cells in the images, such as watershed segmentation and boundary detection using dynamic programming. Some segmentation techniques required the positions of the cells to be detected first. This was done either using a multi-scale Laplace of Gaussian (LoG) filter, which detects blob-like objects in an image, or using the extended h-maxima transform. It was found that the performance of the multi-scale LoG-filter as a cell detector could be increased by using information about the cells-positions in the previous image. To track the individual cells through the sequence, the segmented cells in two consecutive images were associated using Bertsekas modified auction algorithm. The association weights were calculated based on distance, correlation and size between possible matching cells. A comparison of three different segmentation methods, evaluated after completing the tracking step, showed that the best system was an algorithm consisting of a multi-scale LoG-filter, followed by cell border detection using dynamic programming. Using that system, 93 % of the cell-to-cell associations in the evaluated sequences were correct. The obtained cell movement data was used for statistical modelling of the cell migration patterns. Using a Hidden Markov Model with two states, it was found that the motion of the glial progenitor cell was random 2/3 of the time, while the type-2 astrocyte showed a directed movement 2/3 of the time. This finding indicates possibilities for cell-type specific identification and cell sorting of live cells based on specific movement patterns in individual cell population, which would have a valuable application in neurobiological research.
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| 3. |
- Althueser, L., et al.
(författare)
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GPU-based optical simulation of the DARWIN detector
- 2022
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 17:7
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Tidskriftsartikel (refereegranskat)abstract
- Understanding propagation of scintillation light is critical for maximizing the discovery potential of next-generation liquid xenon detectors that use dual-phase time projection chamber technology. This work describes a detailed optical simulation of the DARWIN detector implemented using Chroma, a GPU-based photon tracking framework. To evaluate the framework and to explore ways of maximizing efficiency and minimizing the time of light collection, we simulate several variations of the conventional detector design. Results of these selected studies are presented. More generally, we conclude that the approach used in this work allows one to investigate alternative designs faster and in more detail than using conventional Geant4 optical simulations, making it an attractive tool to guide the development of the ultimate liquid xenon observatory.
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- Altieri, Alessandra, et al.
(författare)
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Blue growth zones caused by Fe2+ in tourmaline crystals from the San Piero in Campo gem-bearing pegmatites, Elba Island, Italy
- 2022
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Ingår i: Mineralogical magazine. - : Mineralogical Society. - 0026-461X .- 1471-8022. ; 86:6, s. 910-919
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Tidskriftsartikel (refereegranskat)abstract
- Two tourmaline crystals with a blue growth zone at the analogous pole, respectively from the San Silvestro and the Fucili pegmatites, located in the San Piero in Campo village, Elba Island (Tyrrhenian Sea, Italy), have been described for the first time using compositional and spectroscopic data to define their crystal-chemical aspects and the causes of the colour. Compositional data obtained by electron microprobe analysis indicate that both tourmalines belong to the elbaite–fluor-elbaite series. The upper part of each crystal is characterised by an increased amount of Fe (FeO up to ~1 wt.%) and a Ti content below the detection limit. Optical absorption spectra recorded on the blue zone of both samples show absorption bands caused by spin-allowed d-d transitions in [6]-coordinated Fe2+, and no intervalence charge transfer Fe2+-Ti interactions, indicating that Fe2+ is the only chromophore. Mössbauer analysis of the blue zone of the Fucili sample confirmed the Fe2+ oxidation state, implying that the redox conditions in the crystallisation environment were relatively reducing. The presence of colour changes at the analogous termination during tourmaline crystal growth suggests a change in the composition of the crystallisation environment, probably associated with a partial opening of the system.
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- Bi, Z. M., et al.
(författare)
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A Study on Optimal Machine Setups Using an Energy Modeling Approach
- 2012
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Ingår i: 40th North American Manufacturing Research Conference 2012. - : Society of Manufacturing Engineers, North American Manufacturing Research Institution of SME. - 9781622762477 ; , s. 571-579, s. 571-579
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Konferensbidrag (refereegranskat)abstract
- In this paper, energy models are developed based on the kinematic and dynamic behaviors of chosen machine tools. One significant benefit of the developed energy models is their inherited relationship to the design variables involved in the manufacturing processes. Therefore, they can be readily applied to optimize process parameters to reduce energy consumption. A new parallel kinematic machine Exechon is used as a case study to demonstrate the procedures of energy model development with direct relation to appropriate process parameters. The derived energy model is then used for simulation of drilling operations on aircraft components to demonstrate its feasibility. Simulation results indicate that the developed energy model has led to an optimized machine setup which only consumes less than one-third of the energy of an average machine setup over the workspace. This approach can be extended and applied to other machines to establish their energy models for green manufacturing.
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| 7. |
- Bose, Partha Pratim, et al.
(författare)
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Template-directed nucleation and growth of CdS nanocrystal : the role of helical and nonhelical nanofibers on their shape and size
- 2010
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Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 12:3, s. 713-718
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Tidskriftsartikel (refereegranskat)abstract
- This study describes the use of chiral nature of synthetic self-assembled nanofibers for nucleation and growth of Cadmium sulfide (CdS) nanocrystals with different sizes and shapes in room temperature. The templates are built by immobilizing a peptide capping agent on the surface of synthetic self-assembled helical or nonhelical nanofibers and CdS nanocrystals were allowed to grow on them. It is observed that there are differences in shapes and sizes of the nanocrystals depending on the chiral nature of the nanofibers on which they were growing. Even the CdS nanocrystals grown on different chiral and achiral nanofibers differ markedly in their photoluminescence properties. Thus, here we introduce a new way of using chirality of nanofibers to nucleate and grow CdS nanocrystals of different shape, size, and optical property.
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| 8. |
- Bose, Subhojyoti, et al.
(författare)
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On The Noise And Power Performance Of A Shoe-Mounted Multi-Imu Inertial Positioning System
- 2017
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Ingår i: 2017 international conference on indoor positioning and indoor navigation (ipin). - : IEEE.
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Konferensbidrag (refereegranskat)abstract
- Shoe-mounted inertial navigation systems, aka pedestrian dead reckoning or PDR sensors, are being preferred for pedestrian navigation because of the accuracy offered by them. Such shoe sensors are, for example, the obvious choice for real time location systems of first responders. The opensource platform OpenShoe has reported application of multiple IMUs in shoe-mounted PDR sensors to enhance noise performance. In this paper, we present an experimental study of the noise performance and the operating clocks based power consumption of multi-IMU platforms. The noise performances of a multi-IMU system with different combinations of IMUs are studied. It is observed that four-IMU system is best optimized for cost, area and power. Experiments with varying operating clocks frequency are performed on an in-house four-IMU shoe-mounted inertial navigation module (the Oblu module). Based on the outcome, power-optimized operating clock frequencies are obtained. Thus the overall study suggests that by selecting a well-designed operating point, a multi-IMU system can be made cost, size and power efficient without practically affecting its superior positioning performance.
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| 9. |
- Bose, Tanima, et al.
(författare)
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Role of ion channels in regulating Ca2+ homeostasis during the interplay between immune and cancer cells.
- 2015
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Ingår i: Cell Death and Disease. - : Springer Science and Business Media LLC. - 2041-4889. ; 19:6
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Forskningsöversikt (refereegranskat)abstract
- Ion channels are abundantly expressed in both excitable and non-excitable cells, thereby regulating the Ca2+ influx and downstream signaling pathways of physiological processes. The immune system is specialized in the process of cancer cell recognition and elimination, and is regulated by different ion channels. In comparison with the immune cells, ion channels behave differently in cancer cells by making the tumor cells more hyperpolarized and influence cancer cell proliferation and metastasis. Therefore, ion channels comprise an important therapeutic target in anti-cancer treatment. In this review, we discuss the implication of ion channels in regulation of Ca2+ homeostasis during the crosstalk between immune and cancer cell as well as their role in cancer progression.
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| 10. |
- Bosem Baillod, Aliette, et al.
(författare)
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Landscape-scale interactions of spatial and temporal cropland heterogeneity drive biological control of cereal aphids
- 2017
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901. ; 54:6, s. 1804-1813
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Tidskriftsartikel (refereegranskat)abstract
- Agricultural landscapes are characterised by dynamic crop mosaics changing in composition and configuration over space and time. Although semi-natural habitat has been often shown to contribute to pest biological control, the effects of increasing landscape heterogeneity with cropland have been disregarded. Here, we examine how cereal aphids, their enemies and biological control are affected by the composition and configuration of the crop mosaic and its inter-annual change due to crop rotation. We studied the abundance of cereal aphids, natural enemies and aphid parasitism over 2 years on 51 winter wheat fields. Arthropods were monitored at three distances (0, 10, 30 m) from field borders. Fields were embedded in landscapes of 1-km diameter selected along orthogonal gradients of compositional crop heterogeneity (crop diversity), configurational heterogeneity (field border and grassy field boundary length) and inter-annual change in cover of aphid host habitats (cereal, maize and grassland). We aimed to disentangle spatial and temporal heterogeneity effects through these independent landscape gradients. Aphid densities were lower in landscapes with smaller field size (more field borders) coupled with high amounts of grassy field boundaries. Aphid densities decreased also in landscapes with higher crop diversity when the cover of aphid host habitat had decreased from the year before. Aphid natural enemy densities decreased with smaller field size and high amounts of grassy field boundaries. Aphid parasitism decreased with the inter-annual expansion in aphid host habitat, but only in landscapes with small field sizes. Synthesis and applications. Our study shows for the first time that cereal aphid numbers can be reduced by optimising the composition, configuration and temporal heterogeneity of the crop mosaic. We highlight the value of maintaining small field sizes in agricultural landscapes and high densities of grassy boundaries for reducing aphid abundance. Landscape-wide crop diversification can reduce aphid densities as well.
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