Au/Zn Contacts to rho-InP: Electrical and Metallurgical Characteristics and the Relationship Between Them

The metallurgical and electrical behavior of Au/Zn contacting metallization on p-type InP was investigated as a function of the Zn content in the metallization. It was found that ohmic behavior can be achieved with Zn concentrations as small as 0.05 atomic percent Zn. For Zn concentrations between 0.1 and 36 at. percent, the contact resistivity rho(sub c) was found to be independent of the Zn content. For low Zn concentrations the realization of ohmic behavior was found to require the growth of the compound Au2P3 at the metal-InP interface. The magnitude of rho(sub c) is shown to be very sensitive to the growth rate of the interfacial Au2P3 layer. The possibility of exploiting this sensitivity to provide low resistance contacts while avoiding the semiconductor structural damage that is normally attendant to contact formation is discussed

Variational Approach to Hard Sphere Segregation Under Gravity

It is demonstrated that the minimization of the free energy functional for hard spheres and hard disks yields the result that excited granular materials under gravity segregate not only in the widely known "Brazil nut" fashion, i.e. with the larger particles rising to the top, but also in reverse "Brazil nut" fashion. Specifically, the local density approximation is used to investigate the crossover between the two types of segregation occurring in the liquid state, and the results are found to agree qualitatively with previously published results of simulation and of a simple model based on condensation.Comment: 10 pages, 3 figure

Energie- en klimaatmonitor agrosectoren 2011

Onderzoek van Agenschap NL en WUR-LEI in opdracht van het ministerie van Economische Zaken, Landbouw en Innovatie (EL&I). Uit de monitor blijkt dat de Nederandse land- en tuinbouwbedrijven meer elektriciteit produceren dan ze zelf verbruiken. De totale bijdrage van deze sectoren aan de in Nederland gebruikte duurzame energie is 44 procent. Ruim de helft van het energieverbruik van de land- en tuinbouwbedrijven zelf (uitgezonderd de glastuinbouw) is afkomstig uit hernieuwbare bronnen

Classification of various sources of error in range assessment using proton radiography and neural networks in head and neck cancer patients

This study evaluates the suitability of convolutional neural networks (CNN) to automatically process proton radiography (PR) based images. CNNs are used to classify PR images impaired by several sources of error affecting the proton range, more precisely setup and calibration curve errors. PR simulations were performed in 40 head and neck cancer patients, at three different anatomical locations (fields A, B and C, centered for head and neck, neck and base of skull coverage). Field sizes were 26x26cm2 for field A and 4.5x4.5cm2 for fields B and C. Range shift maps were obtained by comparing an unperturbed reference PR against a PR where one or more sources of error affected the proton range. CT calibration curve errors in soft, bone and fat tissues and setup errors in the anterior-posterior and inferior-superior directions were simulated individually and in combination. A CNN was trained for each type of PR field, leading to 3 CNNs trained with a mixture of range shift maps arising from one or more sources of range error. To test the full/partial/wrong agreement between predicted and actual sources of range error in the range shift maps, exact, partial and wrong match percentages were computed for an independent test dataset containing range shift maps arising from isolated or combined errors, retrospectively. The CNN corresponding to field A showed superior capability to detect isolated and combined errors, with exact matches of 92% and 71% respectively. Field B showed exact matches of 80% and 54%, and field C resulted in exact matches of 77% and 41%. The suitability of CNNs to classify PR based images containing different sources of error affecting the proton range was demonstrated. This procedure enables the detection of setup and calibration curve errors when they appear individually or in combination, providing valuable information for the interpretation of PR images

Repeatability in spring arrival dates in Pied Flycatchers varies among years and sexes

Timing of arrival in long-distance migration could have fitness consequences: arrival too early impairs survival chances, whereas arrival too late reduces current reproductive success. Evolution thus may have favoured a phenotype that arrived at the optimal time. However, individuals within populations of long-distance migrant species arrive over a considerable time span, and often show consistency in whether they are early or late. This repeatability in arrival varies between studies, and we hypothesise it to be affected by conditions encountered en route or in winter. Here we report on the spring arrival dates of Pied Flycatchers Ficedula hypoleuca to their Dutch breeding sites during eight consecutive years. Our field estimates of arrival were highly accurate, as validated by geolocator data on 13 individuals. Years differed in mean arrival dates. Within years and sexes, arrival date generally spanned more than two weeks. First-year individuals arrived on average 4-5 days later than older individuals. Using repeated arrival dates of more than 500 individuals we show that (1) the overall arrival repeatabilities were similar for females and males, (2) arrival repeatabilities varied temporally, with individuals in consecutive years having sometimes moderate (R = 0.2) and sometimes rather high (>0.40) repeatabilities, and (3) individual females arrived later in their first than in their second year. In females, repeatabilities of arrival and laying dates were similar. We hypothesize that individual flycatchers have a high individual consistency in their spring migration departure date from the wintering grounds. However, previous studies suggest the expression of this individual schedule to be affected by environmental circumstances at the wintering grounds or by what is encountered en route, determining whether this variation is still present at arrival on the breeding grounds. Sexes seemed to differ in this respect, as year-to-year variation in repeatabilities of timing was explained by individual consistency in females, but not in males. We discuss the relevance of the observed variation for the potential for an evolutionary response when environments change

Optimal Resource Allocation with Delay Guarantees for Network Slicing in Disaggregated RAN

In this article, we propose a novel formulation for the resource allocation problem of a sliced and disaggregated Radio Access Network (RAN) and its transport network. Our proposal assures an end-to-end delay bound for the Ultra-Reliable and Low-Latency Communication (URLLC) use case while jointly considering the number of admitted users, the transmission rate allocation per slice, the functional split of RAN nodes and the routing paths in the transport network. We use deterministic network calculus theory to calculate delay along the transport network connecting disaggregated RANs deploying network functions at the Radio Unit (RU), Distributed Unit (DU), and Central Unit (CU) nodes. The maximum end-to-end delay is a constraint in the optimization-based formulation that aims to maximize Mobile Network Operator (MNO) profit, considering a cash flow analysis to model revenue and operational costs using data from one of the world's leading MNOs. The optimization model leverages a Flexible Functional Split (FFS) approach to provide a new degree of freedom to the resource allocation strategy. Simulation results reveal that, due to its non-linear nature, there is no trivial solution to the proposed optimization problem formulation. Our proposal guarantees a maximum delay for URLLC services while satisfying minimal bandwidth requirements for enhanced Mobile BroadBand (eMBB) services and maximizing the MNO's profit.Comment: 21 pages, 10 figures. For the associated GitHub repository, see https://github.com/LABORA-INF-UFG/paper-FGKCJ-202

Evaluation of interplay and organ motion effects by means of 4D dose reconstruction and accumulation

PURPOSE: Pencil beam scanned proton therapy (PBS-PT) treatment quality might be compromised by interplay and motion effects. Via fraction-wise reconstruction of 4D dose distributions and dose accumulation, we assess the clinical relevance of motion related target dose degradation in thoracic cancer patients. METHODS AND MATERIALS: For the ten thoracic patients (Hodgkin lymphoma and non-small cell lung cancer) treated at our proton therapy facility, daily breathing pattern records, treatment delivery log-files and weekly repeated 4DCTs were collected. Patients exhibited point-max target motion of up to 20 mm. They received robustly optimized treatment plans, delivered with five-times rescanning in fractionated regimen. Treatment delivery records were used to reconstruct 4D dose distributions and the accumulated treatment course dose per patient. Fraction-wise target dose degradations were analyzed and the accumulated treatment course dose, representing an estimation of the delivered dose, was compared with the prescribed dose. RESULTS: No clinically relevant loss of target dose homogeneity was found in the fraction-wise reconstructed 4D dose distributions. Overall, in 97% of all reconstructed fraction doses, D98 remained within 5% from the prescription dose. The V95 of accumulated treatment course doses was higher than 99.7% for all ten patients. CONCLUSIONS: 4D dose reconstruction and accumulation enables the clinical estimation of actual exhibited interplay and motion effects. In the patients considered here, the loss of homogeneity caused by interplay and organ motion did not show systematic pattern and smeared out throughout the course of fractionated PBS-PT treatment. Dose degradation due to anatomical changes showed to be more severe and triggered treatment adaptations for five patients

Injectable enzymatically cross linkable hydrogels:a minimally invasive cell free approach to regenerate chondral defects

Purpose: Focal cartilage defects as a consequence of trauma are a major risk factor for the development of early onset osteoarthritis. These defects still pose a largely unresolved problem for the treating physician. Previously, we have developed an injectable in situ gelating hydrogel that can be applied in an arthroscopic procedure to fill up cartilage defects by simple injection. These hydrogels consist of hyaluronic acid - tyramine and dextran - tyramine conjugates that cross link in in a cell-friendly enzymatic, peroxidase-based reaction, initiated by non-toxic concentrations of H2O2. During the cross linking reaction the hydrogels co-valently attach to the cartilage resulting in strong bonding and fixation of the hydrogel in the defect. These hydrogels possess chemoattractant properties facilitating the ingrowth of cells as demonstrated in an ex vivo chondral plug model opening the possibility for cell-free cartilage repair. The aim of this study is to test the use of these injectable hydrogels for cartilage repair in an orthotopic chondral defect rabbit model side-by-side compared with autologous chondrocyte implantation. In addition, we evaluated the concept in an equine model for focal cartilage defects. Methods: Three male rabbits were sacrificed to establish cultures of primary human chondrocytes for implantation purposes. In a pilot rabbit experiment skeletally mature female rabbits were operated under anesthesia and two 4mm wide chondral defects were created in each knee joint. The defects were left untreated, filled up with hydrogel only, or with hydrogel prior mixed with chondrocytes. The various combinations of hydrogel precursors were injected in a liquid state in the defect and left to settle in a mild enzymatically mediated cross linking reaction which took place within less than 20 seconds. Rabbits were sacrificed 4 weeks and 10 weeks after treatment and tissues were collected for histology. In a pilot experiment two horses were operated under general anaesthesia in a fully arthroscopic procedure. In each knee joint, 5mm wide chondral defects were created. These defects were in the same arthroscopic procedure completely filled with the hydrogel. Synovial fluid was collected after 1, 2, 3, 5, 7 and 14 days after surgery. After two weeks horses were humanely euthanisized and tissue was processed for histology. Results: In pilot experiments in rabbits, chondral defects were completely repaired using the injectable hydrogels after 10 weeks of surgery. Cell-free hydrogels appeared as efficient as cell-containing hydrogels. The data are now confirmed in a larger study group in which treatment with hydrogels is compared to microfracture. In the equine model we demonstrated that the injectable hydrogels could be used to fill up focal chondral defects in an completely arthroscopic procedure. Synovial fluid sampling demonstrated a clinically not relevant small increase in white blood cell count and protein count in the first 2 days after surgery which returned to base-line after 3 to 5 days. Clinical examination and follow up of the operated joints demonstrated normal response to arthroscopic surgery: no adverse effects were noted demonstrating the safety of the procedure. The horses were able to make functional use of their treated legs within a few days and walked normally 2-weeks after surgery. At this time point visual inspection demonstrated the presence of hydrogels in each of the defects. Histological examination demonstrated the presence of cell layers on top of the hydrogel and invasion of cells into the hydrogel both from the top and the bottom. The invading cells were organized in columns, like in normal cartilage, and stained positive for typical chondrocyte markers. They actively deposited glycosaminoglycans. Conclusions: This study demonstrates the feasibility of developing an arthroscopic and completely cell-free treatment of chondral defects. It also demonstrates the presence of populations of migratory cells in the traumatized joint. These cells can actively migrate to and invade an appropriate scaffolding material in vivo and start the deposition of cartilage matrix. In the future, this work may translate into a biomaterial based regenerative treatment of osteoarthritis by harnessing the regenerative potential of these migratory cells