A Design Path for Hierarchical Self-Assembly of Patchy Colloids

Patchy colloids are promising candidates for building blocks in directed self-assembly. To be successful the surface patterns need to both be simple enough to be synthesized, while feature-rich enough to cause the colloids to self-assemble into desired structures. Achieving this is a challenge for traditional synthesis methods. Recently it has been suggested that the surface pattern themselves can be made to self-assemble. In this paper we show that a wide range of functional structures can be made to self-assemble using this approach. More generally we present a design path for hierarchical targeted self-assembly of patchy colloids. At the level of the surface structure, we use a predictive method utilizing universality of patterns of stripes and spots, coupled with stoichiometric constraints, to cause highly specific and functional patterns to self-assemble on spherical surfaces. We use a minimalistic model of an alkanethiol on gold as a model system and demonstrate that, even with limited control over the interaction between surface constituents, we can obtain patterns that causes the colloids themselves to self-assemble into various complex geometric structures. We demonstrate how variations of the same design path cause in-silico self-assembly of strings, membranes, cubic and spherical aggregates, as well as various crystalline patterns.Comment: 8 pages, 5 figure

Predicting self-assembled patterns on spheres with multi-component coatings

Interactions between the components in many-body systems can give rise to spontaneous formation of complex structures. Usually very little is known about the connection between the interactions and the resulting structure. Here we present a theory for self-assembling pattern formation in multi-component systems, formulated as an analytic technique that predicts morphologies directly from the interactions in an effective model. As a demonstration we apply the method to a model of alkanethiols on spherical gold particles, successfully predicting its morphologies and transitions as a function of the interaction parameters. This system is interesting because it has been suggested to provide an effective route to produce patchy colloids.Comment: 5 pages, 4 figure

Unipolar and bipolar operation of InAs/InSb nanowire heterostructure field-effect transistors

We present temperature dependent electrical measurements on n-type InAs/InSb nanowireheterostructurefield-effect transistors. The barrier height of the heterostructure junction is determined to be 220 meV, indicating a broken bandgap alignment. A clear asymmetry is observed when applying a bias to either the InAs or the InSb side of the junction. Impact ionization and band-to-band tunneling is more pronounced when the large voltage drop occurs in the narrow bandgapInSb segment. For small negative gate-voltages, the InSb segment can be tuned toward p-type conduction, which induces a strong band-to-band tunneling across the heterostructucture junction.This work was carried out within the Nanometer Structure Consortium at Lund University and was supported by the Swedish Research Council (VR), the Swedish Foundation for Strategic Research (SSF), and the Knut and Alice Wallenberg Foundation

Patterns and Drivers of Regional Crop Production in Chad

Agriculture constitutes the largest economic sector and professional occupation in Chad, and is undergoing rapid changes due to processes of population increase, institutional reforms, conflicts in neighbouring countries, increasingly globalized trade networks, and environmental changes. But despite their importance for livelihoods and economic growth, the specific patterns and drivers of change in the agricultural sector are however poorly understood. This has mostly been a result of low data availability and a lack of comprehensive research programs to address the agricultural changes of various spatial scales. By analysing crop statistics on a level of detail that have not been done before, this thesis has been able to show how the agricultural production is changing over time and between the different administrative regions in Chad. In general it found that the harvested area has been increasing faster than the yield, and that a majority of the changes have happened under abrupt rather than gradual changes. By using this detailed understanding of the patterns of change, and by combining numerous kinds of relevant datasets on hydrology, demographics, international aid, market prices, conflicts, and agricultural practices, this thesis has evaluated potential factors of these changes with an extent and detail that have not been done before. This evaluation have showed that variations in hydrological conditions, market prices, and food security conditions can be linked to the variability in crop production. By looking at descriptions of livelihood conditions in agricultural areas, factors such as material and technical farm support have been linked to abrupt changes in the crop production for specific areas. Also, the differences in long term change between the administrative regions in Chad have been explained by differences in demographic factors and amount of international aid received. These and similar results are relevant to increase the understanding of how agricultural societies evolve in Chad, and how strategies and interventions can be developed to assist local communities in their objectives. More specifically, the results can be used to evaluate the effects of certain events or policies, and to improve seasonal predictions for crop production and food availability. Beyond Chad, the results and methods developed for this thesis are relevant for application in the wider Sahel, where the agro-ecological and institutional conditions share some key characteristics

Demo Abstract: Smart Antennas Made Practical: The SPIDA Way

WISENET (NES)CONE

Experimental studies of components in the treatment for social anxiety disorder

Social anxiety disorder (social phobia) is a debilitating and common anxiety disorder, with a lifetime prevalence ranging from 6 % to 12 %. The condition has its onset in childhood and early adolescence, affects females more often than males, and if untreated is associated with high risk of developing comorbid anxiety and mood disorders, as well as substance abuse. The increasingly growing body of research during the last decades has helped to understand the mechanisms of social anxiety disorder, and has made possible the development of efficacious cognitive behavioural treatment (CBT) methods for the disorder. However, all clients do not improve as much as desired, and there is room for improvement. To explore the relative effectiveness of separate treatment interventions in isolation, or in interaction, may be critical in attempting to enhance the efficacy of current treatment methods. The present thesis is based on three studies investigating the effects of relatively novel contributions to the treatment repertoire for social anxiety disorder: audio-feedback, imagery rescripting, and experiential self-focused attention. Study I concerned an analogue experimental study showing that cognitive preparation (CP) enhanced the beneficial effects of audio feedback (A-F) in modifying participants` negative self-evaluation. The effects generalised to a second social task and the changes were associated with concomitant reductions on social anxiety measured by explicit self-reports and by an implicit method. Study II was designed to experimentally investigate the effects of imagery rescripting (IR) of early adverse memories in social anxiety disorder. Results indicated that IR reduced the distress associated with memory and recurrent catastrophe images in clients with social anxiety disorder. Also, the intervention led to significant improvements on fear of negative evaluation and fear of social interaction. The content of client’s negative self-judgements was radically improved as reflected in increased positivity, empowerment and attraction. Furthermore, in contrast to previous research, results were obtained without the use of a preceding cognitive restructuring. Study III was an attempt to experimentally explore the effects of two distinct attentional modes on post-event processing: the analytical and the experiential self-focus modes. Using a cross-over design with a sample of socially phobic clients it was demonstrated that the two self-focus modes affected cognitions differently: the experiential mode led to a decreased proportion of negative thoughts and the analytical mode to a reduction on neutral thoughts. Also, negative self-evaluation following an initial performance situation strongly predicted the degree of subsequent negative thinking but only if participants had been subject to an analytical self-focus induction. Supporting previous findings, results showed that an experiential self-focus may have beneficial effects on rumination in social anxiety disorder. Of special interest in this thesis is the emphasis on imagery in the cognitive behavioural treatment for social anxiety disorder. It is suggested that imagery, as opposed to verbal interventions, plays a key role in the access of emotion and promotion of emotional change. The treatment techniques presented here, do all to some extent involve imagery as important elements of the treatment procedures. Clearly, audio feedback with cognitive preparation, and in particular imagery rescripting, relies heavily on imagery to access fear structures and to provide corrective information for the purpose of emotional processing. Similarly, in the experiential ‘mindful’ self-focused attention, images provide an important link to the immediate experience in the moment-to-moment of the social situation. Thus, it is concluded that in the attempts to elaborate current treatment methods, the role of imagery should be given special consideration

Optimizing mechanics and the process of fixing sensor PCB card to optics after active alignment

This report describes the development of a new fixing process when attaching a sensor PCB card to a camera assembly. The thesis focused on cameras which requires calibration to find the optimal position of the sensor PCB card, a process called active alignment. The development process applied for this thesis was derived from the Generic Development Process by Ulrich and Eppinger. Interviewees with project members and experts within Axis Communications AB were the main source of information. From the interviewees’ statements, an interpretation into customer needs was performed. Some of the more important identified needs were to simplify production and minimize the sources of error present with the current solutions. The challenges with the process of fixing the sensor PCB card were broken down to a simpler version, i.e. fixing two arbitrary components. The customer needs were used to evaluate different fixing methods and the most promising methods were selected. A concept generation process was initiated to find possible solutions within each fixing method. The most basic concepts were quickly evaluated through discussion and then later on through a concept scoring, to identify the most promising ideas. Further evaluation of these concepts included more information gathering of the fixing methods and discussions about their implementation into production. Then, the most promising concept was selected. With this concept, the details of the solution were further optimized. Through further testing, new demands of the concept were found and solved, arriving at the final specifications of the concept. The final design solution was validated through more thorough testing. The result is a new general process, which uses UV light curable adhesives. By adding a transparent silicone gasket, control over the adhesive is obtained and results in a simplified as well as significantly improved production chain

Emulation of TPM on Raspberry Pi

The Trusted Platform Module (TPM) is a dedicated microprocessor designed to secure hardware by integrating cryptographic keys into the non-volatile memory of the module. TPM is specified by the Trusted Computing Group (TCG). TCG is an initiative started in 2003 by several multinational semiconductor and IT-companies. The initiative is an effort to develop standards for Trusted Computing where hardware is used to provide security support to software. The TPM is typically connected to the LPC bus on the motherboard of a PC and can be used to create and store cryptographic keys, generate random numbers, hash values and encrypt data. The purpose of this thesis is to develop a TPM learning environment and a laboratory manual for introductory courses in computer security where the students are able to learn about the functionalities of the TPM as a means to secure hardware. The functions of the TPM will be emulated on the ARM based single board computer Raspberry Pi developed by the Raspberry Pi foundation. The TPM commands will be executed from a PC which will connect to the Raspberry Pi remotely through TCP. Several exercises related to TPM and its functionalities are provided as an appendix to this report. The exercises are intended for students or others interested in Trusted Computing. This report also provides exercises related to the creation of TPM applications using TSS (Trusted Computing Software Stack)

Evaluation of technical approaches to pronuclei injection

The transgenic technology makes it possible to introduce specific genetic alterations into the genome of all cells in an organism. This has opened entirely new possibilities to analyse the regulation and function of individual genes in a living  animal. We have established a facility for the production of transgenic mice and have generated 37 different transgenic mouse strains. Here we analyse if the frequency of transgenic offspring correlates with the length of the introduced transgene and/or with the genetic background of the injected eggs. Our data suggest that the transgenic frequency is relatively independent of the length of the construct. The genetic background is more important and we find that specific steps in the process of generating transgenic mice are considerably more efficient in an F2 intercross between C57BL6 and CBA than in inbred C57BL6 mice. Finally we discuss how we have used the transgenic technology to analyse the regulation and function of genes inthe developing nervous system