630 research outputs found
Regulation of sodium intake in the mongolian gerbil
In the present study, two experiments were conducted to examine how the gerbil (Merinos Unguiculatus) responds to a chronic sodium deficiency. Adult male gerbils with a mean body weight of 79.81 grams, were maintained for a baseline period on a normal Purina Rat Chow and then they were placed on a salt-free diet. In addition they had ad lib access to a salt solution and water in a two bottle test situation. The saline concentration was cut in half and doubled to test for regulation. There was no significant overall increase in saline consumption (expressed as a percentage of total consumption), and the saline intake did not increase when concentration was cut in half nor decrease when concentration was doubled. However significant changes in absolute water intakes, food intakes and body weights did occur. Water intakes decreased as the concentration of saline decreased and water intakes increased with the increase in saline concentrations. Average food intakes decreased significantly in two of the three groups for the duration of the experimental manipulations. Average body weights decreased dramatically upon implementation of the diet but they slowly returned to baseline levels. A second group of animals was maintained on the sodium-free diet for 28 days. They were sacrificed at this time and their adrenal weights were compared to a control group\u27s adrenal weights. There was no significant difference in adrenal weights between the two groups. It was postulated that the gerbil has a superior capacity for the retention of sodium and thus a severe deficit was not produced. Suggestions for future study were discussed
Adequate screening of youngsters for depressive characteristics
Introduction. In order to set up an effective early-detection of depressive symptoms in youngsters, the current study aims to investigate whether two measure moments of the Children's Depression Inventory (CDI) improve screening and whether a multi-informant procedure is superior compared to a single-informant procedure thereby controlling for comorbid. symptoms. Method. Youngsters (10-15 years) filled in the CDI and an Anxiety Scale at Time 1 and the CDI and Youth Self Report one week later. Next, a structured clinical interview was administered. The Child Behaviour CheckList was filled in by the parents. Results. Two measure moments of the CDI are not more accurate in capturing disordered mood changes. Furthermore, parent reports were no significant contributor to the variance over and above the CDI. Discussion. A second moment does not increase screening accuracy. Further research on setting up an effective multistage screening procedure for depressive symptoms for youngsters is however necessary
Simulation of Product-Service-Systems piloting with agent-based models (outlined revision)
Product-service systems (PSS) can improve sustainability in terms of responsibility of providers and intensified customer-provider relationships. Therefore, a PSS approach has been applied on the distribution of solar home systems in rural areas of emerging countries to improve quality and increase confidence in this technology. However, many innovative projects fail at the piloting stage because of insufficient validation before implementation. Validation methods for PSS like an integrated gap model (e.g. identification of gaps between deliverables and customers expectations) or interdisciplinary design reviews show its limits on the interdependences between product and service development. A new approach to test PSS involves agent-based simulation models and is presented within this paper. Among system dynamics and discrete event simulation, an agent-based simulation is able to work with less quantitative data and a more detailed view on individual entities than the alternative approaches. Thus, it is possible to create more realistic simulation models to validate especially resource planning of a PSS. Agent-based simulation is used within the MEVIS (Micro Energy Supply Information System) project to model a network of solar home systems which are controlled by remote monitoring in order to improve service processes, e. g. maintenance and repair operations. The pilot test should be carried out efficiently by the preceding virtual validation in the form of a simulation, which is built in NetLogo, a tool that enables modeling of a multi-agent environment. Within this environment, communicating technical artifacts as well as different groups of actors are mapped as agents. As a result, diagrams of relevant parameters like the overall repair costs or the estimated customer's satisfaction are displayed and the resource planning is visually supported. This helps to push a PSS into a new market, where you have to deal with existing resources that must be used efficiently. The contributions in this paper provide the conception and an exemplary presentation of the simulation run
Disruption of the mouse MRF4 gene identifies multiple waves of myogenesis in the myotome
MRF4 (herculin/Myf-6) is one of the four member MyoD family of transcription factors identified by their ability to enforce skeletal muscle differentiation upon a wide variety of nonmuscle cell types. In this study the mouse germline MRF4 gene was disrupted by targeted recombination. Animals homozygous for the MRF4bh1 allele, a deletion of the functionally essential bHLH domain, displayed defective axial myogenesis and rib pattern formation, and they died at birth. Differences in somitogenesis between homozygous MRF4bh1 embryos and their wild-type littermates provided evidence for three distinct myogenic regulatory programs (My1-My3) in the somite, which correlate temporally and spatially with three waves of cellular recruitment to the expanding myotome. The first program (My1), marked initially by Myf-5 expression and followed by myogenin, began on schedule in the MRF4bh1/bh1 embryos at day 8 post coitum (E8). A second program (My2) was highly deficient in homozygous mutant MRF4 embryos, and normal expansion of the myotome failed. Moreover, expression of downstream muscle-specific genes, including FGF-6, which is a candidate regulator of inductive interactions, did not occur normally. The onset of MyoD expression around E10.5 in wild-type embryos marks a third myotomal program (My3), the execution of which was somewhat delayed in MRF4 mutant embryos but ultimately led to extensive myogenesis in the trunk. By E15 it appeared to have largely compensated for the defective My2 program in MRF4 mutants. Homozygous MRF4bh1 animals also showed improper rib pattern formation perhaps due to the absence of signals from cells expressing the My2 program. Finally, a later and relatively mild phenotype was detected in intercostal muscles of newborn animals
Unified Information Access in Product Creation with an Integrated Control Desk
Customers demand for individualized products leads to a large variety of different products in small series and single-unit production. A high flexibility pressure in product creation is one result of this trend. In order to counteract the pressure, the information steadily increasing by Industry 4.0 must be made available at the workplace. Additionally, a better exchange of information between product development, production planning and production is necessary. The improvement of individual systems, like CAD, PDM, ERP and MES, can only achieve this to a limited extent. Since they mostly use systems from different manufacturers, the necessary deeper integration of information is only feasible for SMEs to a limited extend. The presented control desk helps to ensure a more flexible product creation as well as information exchange. It captures information from different IT systems in the production process and presents them integrated, task-oriented and oriented to the user's mental model, e.g. information of the production combined with the 3D model of product parts, or information about product development on the 3D model of the production. The solution is a digital 3D model of the manufacturing environment, which is enriched by billboards for a quick information overview and web service windows to access detailed MES and PDM information. By this, the level of abstraction can be reduced and reacts to changed requirements in the short term, making informed decisions. The interaction with the control stands utilizes the touch skills of mobile and fixed systems such as smartphones, tablets and multitouch tables
Simulating reflected light coronagraphy of Earth-like exoplanets with a large IR/O/UV space telescope: impact and calibration of smooth exozodiacal dust
Observing Earth-like exoplanets orbiting within the habitable zone of
Sun-like stars and studying their atmospheres in reflected starlight requires
contrasts of in the visible. At such high contrast,
starlight reflected by exozodiacal dust is expected to be a significant source
of contamination. Here, we present high-fidelity simulations of coronagraphic
observations of a synthetic Solar System located at a distance of 10 pc and
observed with a 12 m and an 8 m circumscribed aperture diameter space telescope
operating at 500 nm wavelength. We explore different techniques to subtract the
exozodi and stellar speckles from the simulated images in the face-on, the 30
deg inclined, and the 60 deg inclined case and quantify the remaining
systematic noise as a function of the exozodiacal dust level of the system. We
find that in the face-on case, the exozodi can be subtracted down to the photon
noise limit for exozodi levels up to zodi using a simple toy model
for the exozodiacal disk, whereas in the 60 deg inclined case this only works
up to zodi. We also investigate the impact of larger wavefront errors
and larger system distance, finding that while the former have no significant
impact, the latter has a strong (negative) impact. Ultimately, we derive a
penalty factor as a function of the exozodi level and system inclination that
should be considered in exoplanet yield studies as a realistic estimate for the
excess systematic noise from the exozodi.Comment: 20 pages, 9 figures, accepted for publication in A
High Frequency Plasma Enhancement of a Conventional Spark Ignition System to Extend the Operating Range of a Modern Mass-Production Engine
Das Erreichen künftiger Abgas- und Verbrauchsrichtlinien stellt bei der Entwicklung moderner Antriebsstränge eine zunehmend große Herausforderung dar. In der Vergangenheit wurde eine Vielzahl alternativer Zündsysteme vorgestellt, welche die konventionelle Transistor-Funkenzündung ersetzen oder erweitern sollten. Der robuste und einfache Aufbau, die geringe Anzahl an Bauteilen und der hohe maximale Energieeintrag in den Brennraum rechtfertigen dessen Einsatz jedoch bis heute. Die Firma Rosenberger Hochfrequenztechnik GmbH & Co. KG arbeitet zusammen mit der Ruhr-Universität Bochum an einer Erweiterung dieses bewährten Zündkonzepts. Das konventionelle Funkenzündsystem wird hierfür beibehalten und lediglich um einen Pfad zur Einkopplung eines hochenergetischen, hochfrequenten (HF) Signals erweitert. Während des konventionell erzeugten Funkens entsteht zwischen den Elektroden der Zündkerze ein leitfähiger Kanal mit niedriger Impedanz. Da die Leistung der konventionellen Zündspule begrenzt ist, wird zusätzlich in diesen Kanal die Energie des HFSignals eingebracht. Dadurch entsteht eine steuerbare HF-Plasmaentladung zwischen den Elektroden mit einem deutlich größeren Plasmavolumen verglichen mit dem Funken. Sowohl die Dauer als auch die Leistung der HF-Plasmaentladung können beliebig eingestellt werden. Dadurch kann auch außerhalb der bisherigen Betriebsbereichen die für die Entflammung des Gemischs notwendige Energie bereitgestellt werden. Versuche an einem hochentwickelten Großserien-Motor (2017 EA 211 Evo model, Volkswagen AG) zeigten, dass so der Motorlauf in verschiedenen, zündkritischen Betriebspunkten sichergestellt werden konnte. Im Bereich des Leerlaufs konnte beispielsweise ein signifikanter Verbrauchsvorteil festgestellt werden. Bei einer Drehzahl von 1000 min-1, einem indizierten Mitteldruck (pmi) von 1 bar und einer zugehörigen Standardabweichung kleiner als 0.1 bar konnten 14 g/kWh durch den erweiterten Einsatz von interner Abgasrückführung eingespart werden. Neben den motorischen Ergebnissen wird der detaillierte Aufbau des Zündsystems sowie die für eine Analyse des Systems notwendige Messtechnik vorgestellt
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