Empirical Research Plan: Effects of Sketching on Program Comprehension

Sketching is an important means of communication in software engineering practice. Yet, there is little research investigating the use of sketches. We want to contribute a better understanding of sketching, in particular its use during program comprehension. We propose a controlled experiment to investigate the effectiveness and efficiency of program comprehension with the support of sketches as well as what sketches are used in what way.Comment: 5 pages, 0 figures, Proc. International Conference on Agile Software Development (XP'16). Volume 251 of the book series Lecture Notes in Business Information Processing (LNBIP). Springer, 201

Precision absolute measurement and alignment of laser beam direction and position

For the construction of high-precision optical assemblies, direction and position measurement and control of the involved laser beams are essential. While optical components such as beamsplitters and mirrors can be positioned and oriented accurately using coordinate measuring machines (CMMs), the position and direction control of laser beams is a much more intriguing task since the beams cannot be physically contacted. We present an easy-to-implement method to both align and measure the direction and position of a laser beam using a CMM in conjunction with a position-sensitive quadrant photodiode. By comparing our results to calibrated angular and positional measurements we can conclude that with the proposed method, a laser beam can be both measured and aligned to the desired direction and position with 10 μrad angular and 3 μm positional accuracy

Portrayal of fuzzy recharge areas for water balance modelling – a case study in northern Oman

The research project IWAS Oman aims at implementing integrated water resources management (IWRM) to a pilot area in Al Batinah, Oman. This requires – amongst others – a realistic assessment of groundwater recharge to the alluvial aquifer which obviously has to be based upon the extension of recharge areas. In this context, the subsequent investigation focuses on the role of vagueness as regards the portrayal of the areas that provide water for particular aquifers. For that purpose, concepts of fuzziness in spatial analysis are applied to describe possible extents of recharge areas. <br><br> In general, any water assessment is based on clearly delineated boundaries. However, in many cases, aquifer recharge areas are not clearly defined due to the nature of the study area. Hence, surfaces indicating a gradual membership to the recharge area of a particular aquifer are used in this investigation. These surfaces, which are based on available qualitative information, visualise a potential range of spatial extension. With regard to water balance calculations, functional relationships in tabular form are derived as well. Based on a regionalisation approach providing spatially distributed recharge rates, the corresponding recharge volume is calculated. Hence, this methodology provides fuzzy input data for water balance calculations. Beyond the portrayal of one singular aquifer recharge area, this approach also supports the complementary consideration of adjacent areas

A Descent Method for Equality and Inequality Constrained Multiobjective Optimization Problems

In this article we propose a descent method for equality and inequality constrained multiobjective optimization problems (MOPs) which generalizes the steepest descent method for unconstrained MOPs by Fliege and Svaiter to constrained problems by using two active set strategies. Under some regularity assumptions on the problem, we show that accumulation points of our descent method satisfy a necessary condition for local Pareto optimality. Finally, we show the typical behavior of our method in a numerical example

Laser beam steering for GRACE Follow-On intersatellite interferometry

The GRACE Follow-On satellites will use, for the first time, a Laser Ranging Interferometer to measure intersatellite distance changes from which fluctuations in Earth’s geoid can be inferred. We have investigated the beam steering method that is required to maintain the laser link between the satellites. Although developed for the specific needs of the GRACE Follow-On mission, the beam steering method could also be applied to other intersatellite laser ranging applications where major difficulties are common: large spacecraft separation and large spacecraft attitude jitter. The beam steering method simultaneously coaligns local oscillator beam and transmitted beam with the laser beam received from the distant spacecraft using Differential Wavefront Sensing. We demonstrate the operation of the beam steering method on breadboard level using GRACE satellite attitude jitter data to command a hexapod, a six-degree-of-freedom rotation and translation stage. We verify coalignment of local oscillator beam/ transmitted beam and received beam of better than 10 μrad with a stability of 10 μrad/ Hz−−−√ in the GRACE Follow-On measurement band of 0.002...0.1 Hz. Additionally, important characteristics of the beam steering setup such as Differential Wavefront Sensing signals, heterodyne efficiency, and suppression of rotation-to-pathlength coupling are investigated and compared with analysis results

Pressure and Temperature Effect on Hydrogen Sorption of Carbon Material

The paper presents the experimental results of saturation of the carbon material containing nanotubes with hydrogen from the gas. The dependences of hydrogen concentration from pressure (from 0 to 8 atmospheres), at the same temperature for adsorption (-30 degrees Celsius) and different temperatures for desorption were obtained. The temperature has an influence on sorption-desorption process and sorption properties of carbon material. The amount of residual hydrogen depends on saturation parameters

Magnetic resonance imaging analysis of the bioabsorbable Milagro™ interference screw for graft fixation in anterior cruciate ligament reconstruction

Ligament graft fixation with bioabsorbable interference screws is a standard procedure in cruciate ligament replacement. Previous screw designs may resorb incompletely, and can cause osteolysis and sterile cysts despite being implanted for several years. The aim of this study was to examine the in vivo degradation and biocompatibility of the new Milagro™ interference screw (Mitek, Norderstedt, Germany). The Milagro™ interference screw is made of 30% ß-TCP (TriCalcium phosphate) and 70% PLGA (Poly-lactic-co-glycolic acid). In the period between June 2005 and February 2006, 38 patients underwent graft fixation with Milagro™ screws in our hospital. Arthroscopic ACL reconstruction was performed using hamstring tendon grafts in all the patients. MR imaging was performed on 12 randomly selected patients out of the total of 38 at 3, 6 and 12 months after surgery. During the examination, the volume loss of the screw, tunnel enlargement, presence of osteolysis, fluid lines, edema and postoperative screw replacement by bone tissue were evaluated. There was no edema or signs of inflammation around the bone tunnels. At 3, 6 and 12 months, the tibial screws showed an average volume loss of 0, 8.1% (±7.9%) and 82.6% (±17.2%, P < 0.05), respectively. The femoral screws showed volume losses of 2.5% (±2.1%), 31.3% (±21.6%) and 92.02% (±6.3%, P < 0.05), respectively. The femoral tunnel enlargement was 47.4% (±43.8%) of the original bone tunnel volume after 12 months, and the mean tunnel volume of the tibial tunnel was −9.5% (±58.1%) compared to the original tunnel. Bone ingrowth was observed in all the patients. In conclusion, the resorption behaviour of the Milagro™ screw is closely linked to the graft healing process. The screws were rapidly resorbed after 6 months and, at 12 months, only the screw remnants were detectable. Moreover, the Milagro™ screw is biocompatible and osteoconductive, promoting bone ingrowth during resorption. Tunnel enlargement is not prevented in the first months but is reduced by bone ingrowth after 12 months

Combined first-principles statistical mechanics approach to sulfur structure in organic cathode hosts for polymer based lithium–sulfur (Li–S) batteries

Polymer-based batteries that utilize organic electrode materials are considered viable candidates to overcome the common drawbacks of lithium–sulfur (Li–S) batteries. A promising cathode can be developed using a conductive, flexible, and free-standing polymer, poly(4-thiophen-3-yl)benzenethiol) (PTBT), as the sulfur host material. By a vulcanization process, sulfur is embedded into this polymer. Here, we present a combination of electronic structure theory and statistical mechanics to characterize the structure of the initial state of the charged cathode on an atomic level. We perform a stability analysis of differently sulfurized TBT dimers as the basic polymer unit calculated within density-functional theory (DFT) and combine this with a statistical binding model for the binding probability distributions of the vulcanization process. From this, we deduce sulfur chain length (“rank”) distributions and calculate the average sulfur rank depending on the sulfur concentration and temperature. This multi-scale approach allows us to bridge the gap between the local description of the covalent bonding process and the derivation of the macroscopic properties of the cathode. Our calculations show that the main reaction of the vulcanization process leads to high-probability states of sulfur chains cross-linking TBT units belonging to different polymer backbones, with a dominant rank around n = 5. In contrast, the connection of adjacent TBT units of the same polymer backbone by a sulfur chain is the side reaction. These results are experimentally supported by Raman spectroscopy

Analysis of Porcine Pro- and Anti-Inflammatory Cytokine Induction by S. suis In Vivo and In Vitro

Weaning piglets are susceptible to the invasive Streptococcus (S.) suis infection, which can result in septicemia. The aim of this study was to investigate the cytokine profile induced upon S. suis infection of blood, to determine the cellular sources of those cytokines, and to study the potential effects of the induced cytokines on bacterial killing. We measured TNF-α, IL-6, IFN-γ, IL-17A and IL-10 after an experimental intravenous infection with S. suis serotype 2 in vivo, and analyzed whole blood, peripheral blood mononuclear cells (PBMC) and separated leukocytes to identify the cytokine-producing cell type(s). In addition, we used a reconstituted whole blood assay to investigate the effect of TNF-α on bacterial killing in the presence of different S. suis-specific IgG levels. An increase in IL-6 and IL-10, but not in IFN-γ or IL-17A, was observed in two of three piglets with pronounced bacteremia 16 to 20 h after infection, but not in piglets with controlled bacteremia. Our results confirmed previous findings that S. suis induces TNF-α and IL-6 and could demonstrate that TNF-α is produced by monocytes in vitro. We further found that IL-10 induction resulted in reduced secretion of TNF-α and IL-6. Rapid induction of TNF-α was, however, not crucial for in vitro bacterial killing, not even in the absence of specific IgG