Discovering Regularity in Point Clouds of Urban Scenes

Despite the apparent chaos of the urban environment, cities are actually replete with regularity. From the grid of streets laid out over the earth, to the lattice of windows thrown up into the sky, periodic regularity abounds in the urban scene. Just as salient, though less uniform, are the self-similar branching patterns of trees and vegetation that line streets and fill parks. We propose novel methods for discovering these regularities in 3D range scans acquired by a time-of-flight laser sensor. The applications of this regularity information are broad, and we present two original algorithms. The first exploits the efficiency of the Fourier transform for the real-time detection of periodicity in building facades. Periodic regularity is discovered online by doing a plane sweep across the scene and analyzing the frequency space of each column in the sweep. The simplicity and online nature of this algorithm allow it to be embedded in scanner hardware, making periodicity detection a built-in feature of future 3D cameras. We demonstrate the usefulness of periodicity in view registration, compression, segmentation, and facade reconstruction. The second algorithm leverages the hierarchical decomposition and locality in space of the wavelet transform to find stochastic parameters for procedural models that succinctly describe vegetation. These procedural models facilitate the generation of virtual worlds for architecture, gaming, and augmented reality. The self-similarity of vegetation can be inferred using multi-resolution analysis to discover the underlying branching patterns. We present a unified framework of these tools, enabling the modeling, transmission, and compression of high-resolution, accurate, and immersive 3D images

An investigation into the limitations of myocardial perfusion imaging

Myocardial Perfusion Imaging (MPI) plays a very important role in the management of patients with suspected Coronary Artery Disease and its use has grown despite the shortcomings of the technique. Significant progress has been made in identifying the causes of these shortcomings and many solutions been suggested in the literature but the clinical sensitivity and specificity of the technique is still well below optimum. Monte Carlo Simulation is a very useful tool in identifying and guiding the understanding of the existing problems in MPI and this present study utilised this method to establish the basis of the simulations to be used and the way to analyse the results so that many of the causes of the attenuation defects, when using MPI, could be identified. This was achieved by investigating the effect that the different anatomical parts of the thorax have on the attenuation defects caused. A further aspect investigated was the impact that self-absorption in the heart has on these defects. The variability of these defects were further investigated by altering the position and orientation of the heart itself within the thorax and determining the effect it has on the attenuation defects caused. Results indicate that the attenuation caused is a very complicated process, that the self-absorption of the heart plays an extremely important role and the impact of the different positions and orientation of the heart inside the thorax are also significant. The distortion caused on the images by these factors was demonstrated by the intensity losses in the basal part and an over-estimation in the apical parts, which were clearly observable on the final clinical images, with the potential to affect clinical interpretation. Attenuation correction procedures using transmission sources, have been available for some time, but have not been adopted widely, amidst concern that they introduce additional artefacts. This study determined the effectiveness of these methods by establishing the level of correction obtained and whether additional artefacts were introduced. This included the effectiveness of the compensation achieved with the use of the latest commercially available comprehensive correction techniques. The technique investigated was “Flash3D" from Siemens providing transmission based attenuation correction, depth-dependent resolution recovery and scatter correction. The comparison between the defects and intensity losses predicted by the Monte Carlo Simulations and the corrections provided by this commercial correction technique revealed that solution is compensating almost entirely for these problems and therefore do provide substantial progress in overcoming the limitations of MPI. As a result of the improvements gained from applying these commercially available techniques and the accuracy established in this study for the mentioned technique it is strongly recommended that these new techniques be embraced by the wider Nuclear Medicine community so that the limitations in MPI can be reduced in clinical environment. Non-withstanding the above gains made there remains room for improvement by overcoming the of use transmission attenuation correction techniques by replacing them with emission based techniques. In this study two new related emission based attenuation correction techniques have been suggested and investigated and provide a promising prospect of overcoming these limitations

The free energy landscape of retroviral integration

Retroviral integration, the process of covalently inserting viral DNA into the host genome, is a point of no return in the replication cycle. Yet, strand transfer is intrinsically iso-energetic and it is not clear how efficient integration can be achieved. Here we investigate the dynamics of strand transfer and demonstrate that consecutive nucleoprotein intermediates interacting with a supercoiled target are increasingly stable, resulting in a net forward rate. Multivalent target interactions at discrete auxiliary interfaces render target capture irreversible, while allowing dynamic site selection. Active site binding is transient but rapidly results in strand transfer, which in turn rearranges and stabilizes the intasome in an allosteric manner. We find the resulting strand transfer complex to be mechanically stable and extremely long-lived, suggesting that a resolving agent is required in vivo

New approaches in ortho-surgical treatments with stimulate & innovative technology

The aim of this study is to show the effectiveness of laser technology for the exposure of the palatally impacted canines, using a CO2 laser device (Smart US20D®, DEKA - Florence, Italy) and Diodi Laser device (Raffaello, DMT, Lissone, Italy, 980nm +645nm), which can stimulate the spontaneous eruption of the canine, without orthodontic traction application. Moreover, the purpose of this study is to monitor the movement of the impacted tooth after exposure with laser approach with digital technologies. Another aspect of this study is focused on the differences between digital monitoring through scanner and conventional monitoring which is based exclusively on the clinical evaluation of the photos and the study of the plaster casts. The final experimental sample was constituted of 18 patients, 9 females and 9 males; of these 8 patients showed a bilateral inclusion and 10 a mono-lateral inclusion of the canine, for a total of 26 canines. To demonstrate the validity of the technique applied to the study group, a CONTROL GROUP, which included 9 patients with unilateral and bilateral palatally impacted canines (in total 13 canines), treated by a traditional surgical-orthodontic approach, was observed. This experimental project was conducted in order to evaluate the effectiveness of laser surgery as an alternative approach to conventional surgical-orthodontic treatment. After laser exposure, no orthodontics treatment was initiated until the impacted tooth had erupted sufficiently into the palate and the autonomous eruption capacity was assessed. The spontaneous eruption was quantified by measuring the millimeter distance between the cusp of the canine one week after surgery (released from the overlying mucous and bone tissues) and the cusp of the same after 16 weeks from laser surgery. Of the 26 canines under study all of them performed a movement between 2,72 mm and 7,04 mm (mean value: 5,01 mm). Therefore, we can state that, at the end of the evaluation period of 16 weeks, a significant teeth movement was observed. Furthermore, the exposure of part of the dental crown, allowed, in all cases treated, to apply a bracket or a button to align the tooth in the dental arch. Our data suggests that the response of the dental element to the bio-stimulant action of the laser, applied to expose their crown, can be considered effective. Of the values obtained, the ones most distanced from the mean value were considered (the highest values 6,9 and 7,04 and the minimum values 2,72 and 3,12) and the type of inclusion of treated canines to which they refer was evaluated. The four values correspond to canines in bone inclusion; in particular, the millimetric value 7,04 corresponds to a deep inclusion canine. Therefore, from what emerges from our study, no significant correlation was found between the extent of spontaneous eruption (in mm) and the type of inclusion. A further purpose of this study was the evaluation of the possible different action between the CO2 laser (wavelength: 10600 nm; power: 4.5 Watts) used in super-pulsed emission mode (that no have bio-stimulation capacity) and the diode laser (wavelength: 980 nm + 645 nm; power: 4 Watts) used in continuous wave emission mode. Comparing the millimeters of eruption of the canines treated with the two different types of lasers and applying the Student’s T-Test, we found a super-imposable value. Moreover, the study groups (group A and group B) and the control group were compared in terms of mean eruption time, respectively spontaneous or forced by means of a Crozat orthodontic device, activated monthly to allow the displacement of the canines .I n the control group the duration of the orthodontic traction is, on average, 10 months. In the study groups the canine eruption was spontaneous and occurred in an average period of 4 months. It can be stated that, although a forced orthodontic traction was applied in the control group to allow tooth eruption, the eruption times in the study groups were significantly lower. The results obtained indicate the effectiveness of the new approach proposed by us, although performed on a small sample of patients. The results are significant from different points of view. The advantages found in this study are numerous. The main advantages of digital monitoring are the possibility of evaluating parameters that cannot be evaluated analogically and of making measurements of distances normally calculated on plaster casts with compass and rubber with the respective errors. Other advantages are represented by the reduction of work time, due to the abolishing of the need to request plaster casts to the dental technician. Which also means the reduction of the costs of the laboratory and it also means less costs for the patients. By eliminating the steps of the analogue impressions and of the plaster casts, the details are certainly represented with more precision and accuracy and there is a minimum error accumulated. This digital workflow that is created is also managed entirely by a single person, which represents a further saving of time. Moreover, we have clinical advantages, that are the less discomfort of the patient who does not tolerate the classic impressions in alginate and of the orthodontist, and the reduction of the chair time. The application of the digital technologies in the monitoring helps the orthodontist to make clinical decisions supported on measurable data and not just on clinical experience. The our ortho-surgical protocol with the use of different technologies set off to a new concept of work in dentistry, in particular, in the cases characterized by impacted teeth or cases that expect an orthodontic and surgical approach. Finally, a not indifferent aspect consists in the reduce of treatment time, which is an advantage for both the orthodontist and the patient. It is consequence of the reduction of the steps and work-time, and it is due to the real monitoring that can be performed on the patient

A stand-alone compact EUV microscope based on gas-puff target source

We report on a very compact desk-top transmission extreme ultraviolet (EUV) microscope based on a laser-plasma source with a double stream gas-puff target, capable of acquiring magnified images of objects with a spatial (half-pitch) resolution of sub-50 nm. A multilayer ellipsoidal condenser is used to focus and spectrally narrow the radiation from the plasma, producing a quasi-monochromatic EUV radiation (λ = 13.8 nm) illuminating the object, while a Fresnel zone plate objective forms the image. Design details, development, characterization and optimization of the EUV source and the microscope are described and discussed. Test object and other samples were imaged to demonstrate superior resolution compared to visible light microscopy. Lay description Developments in nanoscience demand tools capable of capturing images with a nanometer spatial resolution beyond the capability of well-known visible light microscopes. Herein, we present the design details, development, characterization and optimization of a very compact desk-top transmission microscope, operating in invisible to an eye radiation from the so called extreme ultraviolet (EUV) range. The apparatus is based on a laser-plasma source coupled with a special type of objective called Fresnel zone plate. It is capable of acquiring magnified images of objects with a spatial resolution of sub-50 nm, approximately 5–10 times better than the spatial resolution of classical visible light microscopes, in a short acquisition time. The main motivation for development of such compact systems operating with EUV radiations is the possibility to get information about thin samples due to the easily absorption of these radiation by solid materials with very small thicknesses, of the order of about 100 nm. Additionally, the employment of such kind of microscopes might open the possibility to perform experiments without necessity to employ large ‘photon facilities’ such as synchrotrons or free electron lasers and could have a huge impact on the speed of nanotechnology development. Imaging results, concerning nanostructures and biomedical samples, are presented and discussed

TIR1 AFB Aux IAA auxin perception mediates rapid cell wall acidification and growth of Arabidopsis hypocotyls

Despite being composed of immobile cells, plants reorient along directional stimuli. The hormone auxin is redistributed in stimulated organs leading to differential growth and bending. Auxin application triggers rapid cell wall acidification and elongation of aerial organs of plants, but the molecular players mediating these effects are still controversial. Here we use genetically-encoded pH and auxin signaling sensors, pharmacological and genetic manipulations available for Arabidopsis etiolated hypocotyls to clarify how auxin is perceived and the downstream growth executed. We show that auxin-induced acidification occurs by local activation of H+-ATPases, which in the context of gravity response is restricted to the lower organ side. This auxin-stimulated acidification and growth require TIR1/AFB-Aux/IAA nuclear auxin perception. In addition, auxin-induced gene transcription and specifically SAUR proteins are crucial downstream mediators of this growth. Our study provides strong experimental support for the acid growth theory and clarified the contribution of the upstream auxin perception mechanisms