Are There Rearrangement Hotspots in the Human Genome?

In a landmark paper, Nadeau and Taylor [18] formulated the random breakage model (RBM) of chromosome evolution that postulates that there are no rearrangement hotspots in the human genome. In the next two decades, numerous studies with progressively increasing levels of resolution made RBM the de facto theory of chromosome evolution. Despite the fact that RBM had prophetic prediction power, it was recently refuted by Pevzner and Tesler [4], who introduced the fragile breakage model (FBM), postulating that the human genome is a mosaic of solid regions (with low propensity for rearrangements) and fragile regions (rearrangement hotspots). However, the rebuttal of RBM caused a controversy and led to a split among researchers studying genome evolution. In particular, it remains unclear whether some complex rearrangements (e.g., transpositions) can create an appearance of rearrangement hotspots. We contribute to the ongoing debate by analyzing multi-break rearrangements that break a genome into multiple fragments and further glue them together in a new order. In particular, we demonstrate that (1) even if transpositions were a dominant force in mammalian evolution, the arguments in favor of FBM still stand, and (2) the ‘‘gene deletion’’ argument against FBM is flawed

Strength grading and selected strength properties of European hardwoods

Die Laubholzvorräte werden in Mitteleuropa in Zukunft ansteigen und es ist erklärter politischer Wille, diese Ressourcen im Bauwesen stofflich zu nutzen. Seit der Jahrtausendwende wurden deshalb mehr und mehr öffentliche Mittel für die Laubholzforschung zur Verfügung gestellt. Diese Forschung hat zusammen mit Bemühungen privater Unternehmen zu einer Reihe von europäischen und deutschen technischen Zulassungen für Brettschichtholz aus Laubholz (Eiche, Buche, Edelkastanie, Buche Furnierschichtholz) geführt. Ein weiteres Ergebnis war die Aufnahme der Laubholzarten Buche, Eiche, Ahorn, Esche, Pappel und Edelkastanie in die europäische Norm EN 1912, die die Verwendung dieser Laubhölzer als Vollholz im Bau ermöglicht. Eine weit verbreitete Verwendung dieser Produkte ist derzeit jedoch nicht zu beobachten. Ein Ziel dieser Dissertation war es, die Produktions- und Wertschöpfungsketten von Laub-Konstruktionsholz zu analysieren und Probleme bzw. Optimierungspotentiale entlang dieser zu identifizieren. Zunächst wurde hierfür die Markt- und Normensituation identifiziert und zusammengestellt. Ziel der im Anschluss durchgeführten Versuche war es drängende Fragestellungen in der Produktions- und Wertschöpfungskette von Laubholzprodukten für die konstruktive Anwendung zu beantworten. Besonderes Augenmerk wurde auf das Arbeitsfeld Festigkeitssortierung gelegt, da hier ein deutliches Optimierungspotenzial gesehen wurde. Für die sechs europäischen Laubholzarten Eiche, Buche, Esche, Ahorn, Linde und Birke wurde die Verteilung der Schnittholzmerkmale (eines marktüblichen Sortiments) ermittelt und die Holzverfügbarkeit untersucht, um die Eignung der Holzart für eine breitere Verwendung im Bauwesen zu bewerten. Für Esche und Ahorn wurde eine Ausbeuteanalyse vom Langholzabschnitt bis zur sortierten BSH-Lamelle durchgeführt. Diese Untersuchung verdeutlichte die Notwendigkeit einer verbesserten Sägetechnologie, einer schnelleren Trocknungstechnik und einer angepassten Sortierung. Ein wichtiges Schnittholz-Sortiermerkmal ist die sogenannte Faserneigung. Diese korreliert stark mit der Zugfestigkeit von BSH-Lamellen. Nach Ansicht von Experten auf dem Gebiet ist es nicht möglich den exakten Faserwinkel für Laubschnittholz zerstörungsfrei zu bestimmen. Im Rahmen dieses Projektes wurde nachgewiesen, dass es außer für Eschenholz für alle oben genannten Laubholzarten möglich ist, den Faserwinkel maschinell zu bestimmen. Abhängig von der Sortierung treten bei den Festigkeiten und Steifigkeiten der Holzbauteile Größeneffekte auf. Diese wurden für alle sechs oben genannten Holzarten im Biege-, Zug- und Druckversuch parallel zur Faser untersucht. Zusätzlich wurden im Druck- und Zugversuch quer zur Faser Festigkeiten, Steifigkeiten und Versagensmodi für Ahorn, Esche und Buche evaluiert. Weitere Materialkennwerte wurden in Zugversuchen parallel zur Faser an BSH-Lamellen ermittelt und diese mit visuellen und maschinellen Sortierergebnissen korreliert. Diese Experimente zeigten die zum Teil ungenutzten Potentiale bezüglich Festigkeiten und Steifigkeiten einiger Laubhölzer, aber auch die Schwierigkeit die Materialausbeute zu erhöhen.Since national standing stocks of hardwoods will be rising in central Europe in the future, it is the declared political will to introduce these resources to a higher extent into the building sector. That is why since the turn of the century more and more funds for hardwood research have been made available. This research together with efforts made by private companies has led to a number of European and German technical approvals for hardwood glulam (oak, beech, sweet chestnut, beech LVL). A further result was the inclusion of the hardwood species beech, oak, maple, ash and poplar into the European standard EN 1912, which allows the use of these hardwoods as solid wood product in construction. Nonetheless, a wide-spread use of these products cannot be witnessed at present. One goal of this dissertation was to identify reasons for this development. Next to market driven causes like a still sufficient availability of softwood and high prices of hardwood products, technological reasons (problems) regarding hardwood glulam and solid wood were identified. In the course of this dissertation, it was aimed to answer some of these technical questions, in order to work towards a more reliable and cost reduced (etc.) hardwood construction product. First, the market and standard situation was identified and put together. The subsequent research was designed to create answers to pressing questions connected to the work field of strength grading. Here, a raised improvement potential was seen. For the six European hardwood species oak, beech, ash, maple, lime and birch the distribution of sawn wood characteristics (of a typical, market available assortment) were determined and the timber availability examined, in order to evaluate the suitability of the species for a wider use in construction. For the species ash and maple, a yield analysis from round wood sections to sorted glulam lamellas was carried out, which pointed out the need for an improved sawing technique (incl. sawing pattern), a faster drying technology and optimized strength grading. When it comes to strength grading, the grain angle is highly correlated with the final tensile strength of the glulam lamella. According to experts on the field, it is not possible to determine the grain angle on hardwoods in a non-destructive way. In the course of this dissertation, it was proven that for five of the six above-mentioned hardwood species (except ash) it is possible to determine the grain angles by machine use. Also, in this field of work falls the topic “size effect”, which was examined for bending, tension and compression parallel to grain (for all six species). Mechanical properties in tension and compression testing perpendicular to grain were examined for ash, maple and beech construction timber. In addition, tension tests on glulam lamellas were carried out and the results correlated with the sorting results. These experiments revealed the unused potentials (in standard strength values) of some of the hardwoods, but also pointed out the difficulties in raising the final yield (i.e. lower production costs)

Composites from Recycled and Modified Woods

Recycled woods obtained from old buildings, furniture, industrial products, etc., as well as from modified woods prepared by thermal, chemical, or biological processes, have the potential to be a base or complementary raw material for construction and decorative wood composites used mostly in buildings, furniture, and for transport. Typical construction composites are glued prisms and boards (e.g., glulam, blockboard), glued large-area boards from veneers (e.g., plywood, laminated veneer lumber), or large-area boards from wood particles and fibers (e.g., particleboard, oriented strand board, medium-density fiberboard). More of the large-area boards can obtain a better decorative function usable in furniture and building architecture after veneering, lamination, coating, plasma-treating or other surface-treating technologies.Within this Special Issue, selected articles related primarily to wood composites prepared from recycled and modified woods are presented with a focus on the type and properties of used raw materials, additives, and technological processes, including finishing and surface treatments, with an impact on the resulting properties and service-life of wood composites in different use scenarios

Scalable Sort Automation

The Scalable Sort Automation MQP evaluates the effectiveness of a system level design for an automated sortation system that is scalable to high class count and high volume. Subsystems underwent low level design, prototyping, and evaluation of criteria such as cycle time, cost, and volume. The system architecture couples traditional sorting techniques such as linear grating and serialization with novel machine learning technology. The LEGO catalog is used as a base case in testing the subsystems, the catalog carries a high-class count of close to 70,000 with many of the classes being distinct in size, shape, weight and other mechanical properties and features. The system is then evaluated in an economic model centered around conducting LEGO aftermarket sales through bricklink.com

Obstacle Avoiding Robot using Visual Information

A robot using computer vision to avoid obstacles was built for Depush, a Chinese company specializing in educational robotics. We used the Open Computer Vision library to implement stereo vision for obstacle detection. We then sent commands to the motors using a microcontroller. This robot successfully detected and avoided different kinds of obstacles such as bottles, chairs and walls

Development of a static bioactive stent prototype and dynamic aneurysm-on-a-chip(TM) model for the treatment of aneurysms

Aneurysms are pockets of blood that collect outside blood vessel walls forming dilatations and leaving arterial walls very prone to rupture. Current treatments include: (1) clipping, and (2) coil embolization, including stent-assisted coiling. While these procedures can be effective, it would be advantageous to design a biologically active stent, modified with magnetic stent coatings, allowing cells to be manipulated to heal the arterial lining. Further, velocity, pressure, and wall shear stresses aid in the disease development of aneurysmal growth, but the shear force mechanisms effecting wound closure is elusive. Due to these factors, there is a definite need to cultivate a new stent device that will aid in healing an aneurysm insitu. To this end, a static bioactive stent device was synthesized. Additionally, to study aneurysm pathogenesis, a lab-on-a-chip device (a dynamic stent device) is the key to discovering the underlying mechanisms of these lesions. A first step to the reality of a true bioactive stent involves the study of cells that can be tested against the biomaterials that constitute the stent itself. The second step is to test particles/cells in a microfluidic environment. Therefore, biocompatability data was collected against PDMS, bacterial nanocellulose (BNC), and magnetic bacterial nanocellulose (MBNC). Preliminary static bioactive stents were synthesized whereby BNC was grown to cover standard nitinol stents. In an offshoot of the original research, a two-dimensional microfluidic model, the Aneurysm-on-a-ChipTM (AOC), was the logical answer to study particle flow within an aneurysm sac - this was the dynamic bioactive stent device. The AOC apparatus can track particles/cells when it is coupled to a particle image velocimetry software (PIV) package. The AOC fluid flow was visualized using standard microscopy techniques with commercial microparticles/cells. Movies were taken during fluid flow experiments and PIV was utilized to monito