Mapping vesicle shapes into the phase diagram: A comparison of experiment and theory

Phase-contrast microscopy is used to monitor the shapes of micron-scale fluid-phase phospholipid-bilayer vesicles in aqueous solution. At fixed temperature, each vesicle undergoes thermal shape fluctuations. We are able experimentally to characterize the thermal shape ensemble by digitizing the vesicle outline in real time and storing the time-sequence of images. Analysis of this ensemble using the area-difference-elasticity (ADE) model of vesicle shapes allows us to associate (map) each time-sequence to a point in the zero-temperature (shape) phase diagram. Changing the laboratory temperature modifies the control parameters (area, volume, etc.) of each vesicle, so it sweeps out a trajectory across the theoretical phase diagram. It is a nontrivial test of the ADE model to check that these trajectories remain confined to regions of the phase diagram where the corresponding shapes are locally stable. In particular, we study the thermal trajectories of three prolate vesicles which, upon heating, experienced a mechanical instability leading to budding. We verify that the position of the observed instability and the geometry of the budded shape are in reasonable accord with the theoretical predictions. The inability of previous experiments to detect the ``hidden'' control parameters (relaxed area difference and spontaneous curvature) make this the first direct quantitative confrontation between vesicle-shape theory and experiment.Comment: submitted to PRE, LaTeX, 26 pages, 11 ps-fi

Minor planet astrophotometry

Historically, the Minor Planet Center (MPC) has concentrated on improving the quality of the astrometric observations and the resulting orbits of minor planets. In light of long-standing complaints in the literature about the quality of the photometric parameters for the minor planets, there has been a need to improve the quality of the absolute magnitudes, H, and slope parameters, G. However, this task is complex, as the bulk of the minor-planet magnitude estimates are suppl ied by the astrometric observers. These observations are not made through standard fillers and are made with respect to the (indifferent) magnitudes in numerous astrometric reference catalogues. Such magnitude estimates are labelled "astrophotometry", to reflect their low quality. This thesis describes a method for correcting the catalogue- and observer-specific errors present in the astrophotometry. This method was applied to more than 70 million astrometric observations with magnitude estimates. New H determinations have been made for 322 607 numbered minor planets, while new G determinations have been made for 64 348 numbered minor planets. New assumed G values have been determined for 258 259 numbered minor planets. Analysis of the results shows that the problems identified in the literature have been removed, particularly the -0.5 magnitude offset at H≈14 that is present in the current MPC HG data set. Implications of the new H magnitudes on the albedos determined by the WISE space mission and on the differential H distributions of various types of solar-system object are discussed

Biodegradable liposome-encapsulated hydrogels for biomedical applications: a marriage of convenience

Hydrogels are hydrophilic three-dimensional networks with demonstrated potential for medical and pharmaceutical applications. Specifically, biopolymer-based hydrogels offer certain advantages over synthetic polymers in terms of biocompatibility and biodegradability. Because of their inherent properties, hydrogels are able to efficiently encapsulate and liberate in a controlled release manner, different hydrophobic and hydrophilic therapeutic molecules, including nucleic acids, proteins and antibodies. Several strategies have been reported in the literature to minimize the potential burst release of encapsulated drugs, thus preventing their local accumulation and consequent toxic responses. Within this context, liposomes embedded in hydrogels have emerged as an attractive strategy to reduce this undesirable effect. This tutorial review covers a selection of the most promising cationic, neutral and anionic biopolymer-based hydrogels containing liposomes, niosomes or vesicles for drug delivery or tissue engineering applications.This work is supported by the University of Regensburg, the DFG (DI 1748/3-1), the Spanish Ministry of Education (Grant CTQ2014-52588-R, RTC-2014-2038-1), the Generalitat de Catalunya (2014/SGR/624), the Instituto de Salud Carlos III (CB06_01_0019) and the Spanish Ministry of Education, Culture and Sports. S.G. thanks the Spanish Ministry of Education, Culture and Sports for a “Jose Castillejo” grant within the researchers mobility program (Programa Estatal de Promoción del Talento y su Empleabilidad en I + D + i, Subprograma Estatal de Movilidad, del Plan Estatal de Investigación Científica y Técnica y de Innovación 2013–2016). D. D. D. thanks the Deutsche Forschungsgemeinschaft (DFG) for the Heisenberg Professorship Award. We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)Peer reviewe

Compensation for polarization mode dispersion and nonlinear birefringence in a multichannel optical fibre system

Polarization mode dispersion (PMD) is stochastic in nature and continues evolving in an unpredictable manner according to the changing environment. Nonlinear birefringence in multichannel systems alters the polarization states of the bits, so that they vary from one bit to the next in a way that is difficult to predict. These are the two major signal-impairment effects that are inherent in optical fibre transmission links which can seriously degrade network performance. It is therefore extremely challenging to compensate for both linear and nonlinear birefringence in multichannel systems. The purpose of this thesis is to investigate the interaction between PMD and nonlinear induced birefringence in a fibre with consideration of mode coupling. A sound knowledge of this interaction is necessary in designing a linear and nonlinear polarization mode dispersion compensator for WDM systems, as was successfully carried out in this study. The investigation shows that the effect of nonlinear birefringence alone depolarizes the signal, while in high PMD links where polarization mode coupling is high, the nonlinear birefringence effect couples with second-order PMD such that it may reduce the penalty and improve the signal DOP. Further investigation shows that when nonlinear birefringence becomes significant, asymmetry arises between the two principal axes of the fibre, such that it is only one axis which experiences the effect of nonlinear birefringence. It is found out that along this vii axis, there exists a critical point in pump power where the nonlinear birefringence cancels PMD in the link and improves the signal. An adaptive compensator to cancel PMD and nonlinear birefringence was designed based on feedforward DOP-monitoring signal. The compensator was tested both at laboratory level and on the Telkom buried fibre link and found to be functioning as intended. It was able to adaptively track and compensate PMD in the link in less than a second. The compensator was able to cancel PMD in the link up to a maximum of 30 ps. The compensator improved the DOP of the worst signal by more than 100 percent

The use of Unmanned Aerial Vehicle based photogrammetric point cloud data for winter wheat intra-field variable retrieval and yield estimation in Southwestern Ontario

Precision agriculture uses high spatial and temporal resolution soil and crop information to control the crop intra-field variability to achieve optimal economic benefit and environmental resources sustainable development. As a new imagery collection platform between airborne and ground measurements, Unmanned Aerial Vehicle (UAV) is used to collect high spatial resolution images at a user selected period for precision agriculture. Most studies extract crop parameters from the UAV-based orthomosaic imagery using spectral methods derived from the satellite and airborne based remote sensing. The new dataset, photogrammetric point cloud data (PCD), generated from the Structure from Motion (SfM) methods using the UAV-based images contains the feature’s structural information, which has not been fully utilized to extract crop’s biophysical information. This thesis explores the potential for the applications of the UAV-based photogrammetric PCD in crop biophysical variable retrieval and in final biomass and yield estimation. First, a new moving cuboid filter is applied to the voxel of UAV-based photogrammetric PCD of winter wheat to eliminate noise points, and the crop height is calculated from the highest and lowest points in each voxel. The results show that the winter wheat height can be estimated from the UAV-based photogrammetric PCD directly with high accuracy. Secondly, a new Simulated Observation of Point Cloud (SOPC) method was designed to obtain the 3D spatial distribution of vegetation and bare ground points and calculate the gap fraction and effective leaf area index (LAIe). It reveals that the ground-based crop biophysical methods are possible to be adopted by the PCD to retrieve LAIe without ground measurements. Finally, the SOPC method derived LAIe maps were applied to the Simple Algorithm for Yield estimation (SAFY) to generate the sub-field biomass and yield maps. The pixel-based biomass and yield maps were generated in this study revealed clearly the intra-field yield variation. This framework using the UAV-based SOPC-LAIe maps and SAFY model could be a simple and low-cost alternative for final yield estimation at the sub-field scale. The results of this thesis show that the UAV-based photogrammetric PCD is an alternative source of data in crop monitoring for precision agriculture

Are All Pixels Equally Important? Towards Multi-Level Salient Object Detection

When we look at our environment, we primarily pay attention to visually distinctive objects. We refer to these objects as visually important or salient. Our visual system dedicates most of its processing resources to analyzing these salient objects. An analogous resource allocation can be performed in computer vision, where a salient object detector identifies objects of interest as a pre-processing step. In the literature, salient object detection is considered as a foreground-background segmentation problem. This approach assumes that there is no variation in object importance. Only the most salient object(s) are detected as foreground. In this thesis, we challenge this conventional methodology of salient-object detection and introduce multi-level object saliency. In other words, all pixels are not equally important. The well-known salient-object ground-truth datasets contain images with single objects and thus are not suited to evaluate the varying importance of objects. In contrast, many natural images have multiple objects. The saliency levels of these objects depend on two key factors. First, the duration of eye fixation is longer for visually and semantically informative image regions. Therefore, a difference in fixation duration should reflect a variation in object importance. Second, visual perception is subjective; hence the saliency of an object should be measured by averaging the perception of a group of people. In other words, objective saliency can be considered as the collective human attention. In order to better represent natural images and to measure the saliency levels of objects, we thus collect new images containing multiple objects and create a Comprehensive Object Saliency (COS) dataset. We provide ground truth multi-level salient object maps via eye-tracking and crowd-sourcing experiments. We then propose three salient-object detectors. Our first technique is based on multi-scale linear filtering and can detect salient objects of various sizes. The second method uses a bilateral-filtering approach and is capable of producing uniform object saliency values. Our third method employs image segmentation and machine learning and is robust against image noise and texture. This segmentation-based method performs the best on the existing datasets compared to our other methods and the state-of-the-art methods. The state-of-the-art salient-object detectors are not designed to assess the relative importance of objects and to provide multi-level saliency values. We thus introduce an Object-Awareness Model (OAM) that estimates the saliency levels of objects by using their position and size information. We then modify and extend our segmentation-based salient-object detector with the OAM and propose a Comprehensive Salient Object Detection (CSD) method that is capable of performing multi-level salient-object detection. We show that the CSD method significantly outperforms the state-of-the-art methods on the COS dataset. We use our salient-object detectors as a pre-processing step in three applications. First, we show that multi-level salient-object detection provides more relevant semantic image tags compared to conventional salient-object detection. Second, we employ our salient-object detector to detect salient objects in videos in real time. Third, we use multi-level object-saliency values in context-aware image compression and obtain perceptually better compression compared to standard JPEG with the same file size

The Novel Image Signal Analysis of Monitoring Video Based on CMOS Image Sensor

The image sensor is the most important part of video and still image processing line in digital video or still camera. Data of CMOS process will produce noise in long transmission distance; therefore it must first be amplified and integrated each pixel data. The choice of medium and apparatus for transmitting image and the other the control signal will be directly related to the quality and reliability of the monitoring system. CMOS image sensor has the characteristics of low power, high integration and flexible function. The paper proposes the novel image signal analysis of monitoring video based on CMOS image sensor. In this paper, simulation results shows by using analog signal hardware simulation that the system can achieve the intended function and achieve the ideal effect

Nanobiotechnologie: Werkzeuge für die Proteomik : molekulare Organisation und Manipulation von Proteinen und Proteinkomplexen in Nanodimensionen

First milestone of this Ph.D. thesis was the successful extension of conventional NTA/His-tag technique to self-assembling, multivalent chelator thiols for high-affinity recognition as well as stable and uniform immobilization of His-tagged proteins on chip surfaces. Bis-NTA was linked via an oligoethylene glycol to alkyl thiols by an efficient modular synthesis strategy yielding a novel, multivalent compound for formation of mixed SAMs with anti-adsorptive matrix thiols on gold. Multivalent chelator chips allow a specific, high-affinity, reversible, long-term immobilization of His-tagged proteins. In AFM studies reversibility of the specific protein immobilization process was visualized at single molecule level. The entire control over the orientation of the immobilized protein promotes this chip surface to an optimal platform for studies focusing on research targets at single molecule level and nanobiotechnology. Based on the constructed protein chip platform above and a novel AFM mode (contact oscillation mode, COM) – developed during the current Ph.D. work – protein nanolithography under physiological conditions enabling fabrication of active biomolecular patterns in countless variety has been established. Reversible COM-mediated nanostructuring is exceptionally suitable for multiplexed patterning of protein assemblies in situ. The first selfassembled protein layer acts as a biocompatible and ductile patterning material. Immobilized proteins can be replaced by the AFM tip applying COM, and the generated structures can be erased and refilled with different proteins, which are immobilized in a uniform and functional manner. Multi-protein arrays can be systematically fabricated by iterative erase-and-write processes, and employed for protein-protein interaction analysis. Fabrication of two-dimensionally arranged nanocatalytic centres with biological activity will establish a versatile tool for nanobiotechnology. As an alternative chip fabrication approach, the combined application of methodologies from surface chemistry, semiconductor technology, and chemical biology demonstrated successfully how pre-patterned templates for micro- and nanoarrays for protein chips are fabricated. The surface physical, as well the biophysical experiments, proved the functionality of this technology. The promises of such process technology are fast and economic fabrication of ready-to-use nanostructured biochips at industrial scale. Membrane proteins are complicated in handling and hence require sophisticated solutions for chip technological application. A silicon-on-insulator (SOI) chip substrate with microcavities and nanopores was employed for first technological investigation to construct a protein chip suitable for membrane proteins. The formation of an artificial lipid bilayer using vesicle fusion on oxidized SOI cavity substrates was verified by CLSM. Future AFM experiments will give further insights into the chip architecture and topography. This will provide last evidence of the sealing of the cavity by the lipid bilayer. Transmembrane proteins will be employed for reconstitution experiments on this membrane protein chip platform. Highly integrated microdevices will find application in basic biomedical and pharmaceutical research, whereas robust and portable point-of-care devices will be used in clinical settings.Erster Meilenstein der vorliegenden Arbeit war die erfolgreiche Erweiterung des konventionellen NTA/His-tag-Konzepts auf selbst-assemblierende, multivalente Chelatorthiole für die hochaffine Erkennung und stabile, einheitliche Immobilisierung His-getaggter Proteine auf Chipoberflächen. Mittels einer effizienten, modularen Synthesestrategie wurden Bis-NTA-Module über Oligoethylenglykoleinheiten an Alkylthiole angebunden. Diese Chelatorthiole wurden zusammen mit antiadsorptiven Matrixthiolen zur Ausbildung gemischter selbst-assemblierender Monolagen (SAMs) auf Goldoberflächen eingesetzt. Die multivalenten Chelatorchips erlauben eine spezifische, hochaffine, umkehrbare und langfristige Immobilisierung His-getaggter Proteine. Die Umkehrbarkeit der spezifischen Proteinimmobilisierung wurde in rasterkraftmikroskopischen (AFM) Studien bis zur Einzel-Molekül-Ebene visualisiert. Die vollständige Kontrolle über die Orientierung immobilisierter Proteine qualifiziert diese entwickelte Chipoberfläche zu einer optimalen Plattform für Anwendungsbereiche der Einzelmolekülbiochemie und Nanobiotechnologie. Basierend auf dieser Plattform für Proteinchips und einem – im Rahmen dieser Arbeit – neuentwickelten AFM-Modus (Kontaktoszillationsmodus, COM) wurde die „Protein-Nanolithographie“ etabliert, welche die Fabrikation von aktiven, biomolekularen Strukturen in unzähliger Vielfalt ermöglicht. Die umkehrbare COM-vermittelte Nanolithographie ist insbesondere für die multiplexe Anordnung von Proteinverbänden in situ geeignet. Die erste Schicht immobilisierter Proteine fungiert als ein biokompatibles und verformbares Strukturierungsmaterial. Diese immobilisierten Proteine können nun im Kontaktoszillationsmodus mit der AFM-Spitze lokal entfernt („Löschen“) und gegen andere Proteine – die an die freigelegte Chipoberfläche ebenfalls spezifisch und funktional immobilisieren – ausgetauscht werden („Schreiben“). Arrays, bestehend aus mehreren unterschiedlichen Proteinen können nun systematisch in iterativen Lösch-und-Schreib-Vorgängen fabriziert und für Proteininteraktionsanalysen eingesetzt werden. Die Fabrikation von zwei-dimensional arrangierten nanokatalytischen Zentren mit biologischer Aktivität wird von großem Nutzen für die Nanobiotechnologie sein. Eine alternative Herstellungsmethode aus einer Kombination von Oberflächenchemie, Halbleitertechnologie und chemischer Biologie wurde für die Fabrikation von vorstrukturierten Templaten für Mikro- und Nanoarrays entwickelt. Die Funktionalität dieser Chipplattform wurde anhand oberflächen- und biophysikalischer Experimente erfolgreich gezeigt. Zukünftiges Ziel ist die Anfertigung vorstrukturierter Template in der Dimension weniger Nanometer zur Ausbildung von Bio-Arrays mit einzelnen Molekülen. Ein weiteres Ziel besteht in der kompletten Verlagerung des Herstellungsprozesses in die Gasphase. Eine Produktion in der Gasphase verspricht eine schnelle und wirtschaftliche Erzeugung sofort einsatzbereiter nanostrukturierter Biochips im industriellen Maßstab. Der Umgang mit Membranproteinen verlangt besondere Vorkehrungen im experimentellen Milieu, ebenso speziell sind die Bedürfnisse in den entsprechenden Chip-Anwendungen. Ein Chip mit Mikrokavitäten und Nanoporen, basierend auf der „Silicon-on-Insulator“ (SOI)-Technologie, wurde für erste technologische Studien zum Entwurf eines Proteinchips für Membranproteine eingesetzt. Künstliche Lipidmembranen wurden auf der SOI-Oberfläche mittels Vesikelfusion ausgebildet und mit konfokaler Laser-Scanning-Mikroskopie gezeigt. Zukünftige AFM-Experimente werden weitere Einsichten in die Chiparchitektur und Topographie ermöglichen. Transmembranproteine werden in Rekonstitutionsexperimenten für funktionale Studien der Membranproteinchips eingesetzt. Anwendungsbereiche solcher hochintegrierten Mikrosysteme sind sowohl in der biologischen Grundlagenforschung als auch in mobilen Diagnostikgeräten im klinischen Einsatz zu finden

Examination of the World3 Model and the Development of a Novel Model of a Multi-market, Multi-regional Economy Driven by Adaptive Heterogeneous Consumer Agents

Ever since the human race developed consciousness we have battled against the elements to bring about prosperity and health. For millennia we closely observed the natural phenomena that seemed to influence future outcomes, gradually building and refining our conceptions of reality, our mental models. We refined the process of observation and discovery with the scientific method, and from that point on our power to control our environment grew immensely. Now our greatest foe is not only Mother Nature, but ourselves. We still act impulsively, and make decisions which seem irrational. We may guiltily watch hour after hour of Antiques Road Show, instead of spending a mere 30 minutes finishing off the final thesis chapter. The tradition of model development is continued herein, with a focus on holistic socio- ecological models. The first part of this thesis examines the pre-existing Limits to Growth model, originally developed by Meadows et. al. in 1972. Uncertainty analysis was per- formed on this model to develop a better understanding of its reliability. This model is also used to better understand the trade-off relationships between common goals humans wish to achieve in the future. A genetic algorithm was used to determine the Pareto front of the seven examined goals. The final part of the thesis presents a novel model designed to allow many simulated human actors to make purchasing decisions in a self determining fashion, based on the cost of various goods. The new model simulates multi-item market- places, floating prices on goods, and spacial effects on trading and resource extraction. A preliminary version of the model is tested under eight different conditions, and the results are presented and discussed