Structures in supercritical scale-free percolation

Scale-free percolation is a percolation model on $\mathbb{Z}^d$ which can be used to model real-world networks. We prove bounds for the graph distance in the regime where vertices have infinite degrees. We fully characterize transience vs. recurrence for dimension 1 and 2 and give sufficient conditions for transience in dimension 3 and higher. Finally, we show the existence of a hierarchical structure for parameters where vertices have degrees with infinite variance and obtain bounds on the cluster density.Comment: Revised Definition 2.5 and an argument in Section 6, results are unchanged. Correction of minor typos. 29 pages, 7 figure

Conventional and manipulated growth of Cu-Cu(111)

Molecular beam epitaxy of Cu on Cu(111) was studied using thermal energy He scattering, in the temperature range between 100 and 450 K. Three-dimensional growth was observed in the whole temperature range. To determine the onset of various diffusion processes, submonolayer films formed by deposition at low temperature were annealed. Annealing proceeds in two steps. The first step is interpreted as a change in island shape, the second as Ostwald-ripening. A comparison with homoepitaxy on Pt(111) and Ag(111) is made. Growth manipulation was carried out by artificially increasing the island number density via intervention in the nucleation stage of each layer. The procedures applied were temperature reduction during nucleation as well as pulsed ion bombardment. These techniques enabled the convenient growth of good quality films consisting of a large number of monolayers. Finally, the use of oxygen as a surfactant modifying the growth mode was investigated. Under some growth conditions, pre-exposure of the surface to oxygen was found to induce weak He-intensity oscillations during deposition. The quality of the films grown in this way was, however, low

Human-computer interaction in radiology

Digitale technologie speelt een cruciale rol in de radiologie. Dit betekent dat de arbeidsprestatie van radiologen voor een groot deel wordt bepaald door hoe goed ze met computersystemen kunnen omgaan. Het is daarom van groot belang dat de gebruikersinterfaces die deze interactie mogelijk maken van hoge kwaliteit zijn en radiologen in staat stellen hun werk met maximale effectiviteit, efficiëntie en tevredenheid uit te voeren.Het doel van dit proefschrift was het bestuderen van de interactie tussen radiologen en computersystemen en het identificeren van manieren om de kwaliteit van deze interactie te verbeteren. We richtten ons op usability-evaluatie, interactietechnieken, gebruikersinterfacepersonalisatie, computergeassisteerde diagnose en gestructureerde verslaglegging.Hoewel de onderwerpen van de onderzoeken beschreven in dit proefschrift sterk varieerden, en elk onderzoek op zichzelf betekenisvolle resultaten heeft opgeleverd, hebben zij één overkoepelende boodschap: naast het bestuderen van digitale technologie zelf is het noodzakelijk om te onderzoeken hoe mensen met deze technologie omgaan. Om kwalitatief hoogstaande gebruikersinterfaces voor radiologische computersystemen te kunnen ontwikkelen moeten we begrijpen hoe de interactie tussen radiologen en deze systemen eruit ziet.Digital technology plays a crucial role in today’s radiology department. This means that the job performance of radiologists is determined to a large extent by how well they can interact with computer systems. It is therefore vital that the user interfaces through which this interaction takes place are of high quality, and allow radiologists to perform their jobs with maximal effectiveness, efficiency, and satisfaction. In this thesis, we aimed to study the interaction between radiologists and computer systems, and to identify ways to improve the quality of this interaction. We focused on usability evaluation, interaction techniques, user interface customization, computer-aided diagnosis, and structured reporting.While the topics of the studies described in this thesis varied greatly, and all of them produced meaningful results on their own, they have one overarching message: in addition to studying digital technology in itself, it is vital to study the way humans interact with it. In order to design high-quality user interfaces for radiological computer systems, we have to understand how radiologists interact with them

Elevated central serotonin levels inhibit emotional crying

Previous research has suggested a possible role of serotonin in emotional expressions, such as crying. We have found that a transient increase of central serotonin levels by means of oral administration of paroxetine reduces crying in response to emotional movies in healthy female volunteers. This is the first direct evidence of an important role of serotonin in this uniquely human emotional response

Nanometer lithography on silicon and hydrogenated amorphous silicon with low-energy electrons

We report the local oxidation of hydrogen terminated silicon (Si) surfaces induced with the scanning-tunneling microscope (STM) operating in air and by a beam of free low-energy electrons. With STM, oxide lines were written in Si(100) and Si(110) and transferred into the substrate by wet etching. In case of Si(110) trenches with a width as small as 35 nm and a depth of 300 nm were made. The same process has also successfully been applied to the patterning of hydrogenated amorphous silicon (a-Si:H) thin films. We demonstrate the fabrication of metallic ‘nanowires’ using a-Si:H as resist layer. With regard to the process of oxidation, it is found that the oxide written with STM is apparently not proportional to the electron current, in contrast to results obtained with a beam of free electrons in an oxygen gas-environment. The dose needed to remove the hydrogen was determined as a function of electron energy. This dose is minimal for 100 eV electrons amounting to 4 mC/cm2

Economic consequences of reproductive performance in dairy cattle

The net economic value of reproductive efficiency in dairy cattle was estimated using a stochastic dynamic simulation model. The objective was to compare the economic consequences of reproductive performance scenarios (“average” and “poor”) of a cow having a good reproductive performance and to explore which reproductive factors have an important impact on economic efficiency. A “good” reproductive performance scenario was defined with 1 ovulation rate (POVUi), 0.7 estrus detection rate (PEst), 0.7 conception rate (PCon), 0.03 incidence rate of postpartum disorders prolonging the ovarian cyclicity (CO), 0.2 incidence rate of postpartum disorders reducing conception (ME), 0.05 embryonic death rate (ED), and voluntary waiting period (VWP) of 9 wks pp (post partum). In the current situation of dairy cows in the Netherlands, an “average” reproductive scenario (0.95 POVUi, 0.5 PEst, 0.5 Pcon, 0.07 CO, 0.27 ME, 0.07 ED and VWP of 12 wks pp) and a “poor” reproductive scenario (0.90 POVUi, 0.3 PEst, 0.3 Pcon, 0.11 CO, 0.33 ME, 0.09 ED and VWP of 15 wks pp) were identified. A sensitivity analysis was performed by comparing changes of single effect of factors in a good and poor scenario with the average scenario. The mean net economic loss (NELi) compared with the good scenario was €34 and €231 per cow per year for the average and poor reproductive performance scenario, respectively. Increasing the calving interval resulted in greater economic loss. The important factors on the cost of reproductive efficiency were the involuntary culling cost and the return of milk production. Variation in PCon, PEst, ME, ED, and VWP had large impacts on economic benefits. Keywords: Dairy cow; Reproductive performance; Simulation model; Economic