The measurement of the pp->K+ n Sigma+ reaction near threshold

It is shown that a recent extraction of the total cross section for pp->K+ n Sigma+ from inclusive K+ production data is in conflict with experimental data on the exclusive pp->K+ p Lambda reaction. The result may be interpreted as an upper bound which is not inconsistent with the much lower values that already exist in the literature.Comment: Submitted to PL

LOCALIZED SURFACE PLASMON RESONANCE OF COPPER NANOPARTICLES USING FINITE ELEMENT METHOD

The aim of this paper is to study the interaction of the electromagnetic wave with plasmonic nanoparticles. Localized Surface Plasmon resonance (LSPR) characteristics are governed by the intrinsic properties of the nanoparticle (size, shape and dielectric environment). The extinction cross-section spectra of Cu nanoparticles are calculated using finite element method (FEM). By increasing both the size of the nanoparticle and the dielectric environment, the simulations show a red-shifting and broadening on the LSPR spectrum with enhancement of the spectral amplitude. The extinction cross section spectra are calculated using polarized light for non-spherical or assembled nanoparticles. We investigated the LSPR of Cu nanospheres of different arrangements, showing that the optical response depends on the order of nanospheres and the light polarization

Coastal Flood Protection for Liquefied Natural Gas Developments – Understanding Risks And Returns

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

The Blurred Line between “Long” and “Short”: How the Length of Video Lectures Affects the Viewing Behavior of E-Learners

Recent research has focused on the impact of video lectures on students’ academic performance rather than the viewing behavior of learners. In this study, we investigate the learners’ preferences of video lectures in terms of the length as well as the devices used to access the online learning material. We published two versions of video lectures on two YouTube channels. The online material was produced by recording a real face-to-face class context at the Arab Open University. The video recorded material belongs to a first level course offered to students at the Faculty of Computer Studies. The first version of the online lectures comprised 7 videos and is, hence, called long-run version. The second version, termed as short-run version, consisted of 28 video lectures. Video contents are identical in both versions. Total recording time amounted to 528 minutes in both video versions with an average of 75 and 19 minutes in long-run and short-run versions, respectively. We found that though students alternated between the use of mobile phones, tablets and desktops, however, they mainly accessed the online material through desktops. Moreover, students spent a total of 43765 minutes in viewing the long-run videos compared with 4766 minutes spent on the short-run ones. Considering the number of views (3143 for the long-run and 846 views for the short-run videos) yields average viewing times of 13.92 and 5.63 minutes per views for the long-run and short-run videos, respectively. This is interesting, for these results show that students are willing to spend approximately 14 minutes when viewing an approximately 75 minutes long video lecture, but when offered a 22 minutes long alternative, the time they spend in viewing does not exceed 6 minutes on average. Our results imply that students do access the online video lectures for learning purposes. However, more should be done, so as to approach near-optimal lengths of video lectures that facilitate a complete viewing of the learning material. Keywords: Video lectures, Blended learning, Viewing behavior, Big data analysi

Contact-Less Measurement System for Cardiopulmonary Activity

International audienceThis paper presents a wireless cardiopulmonary activity measurement system. This system generates a continuous wave toward a person's chest set at a distance of 1 m, then reflected to the system. Using a vector network analyzer, the phase of S21 is computed. The phase variation of S21 contains information about cardiopulmonary activity. Several processing techniques are used to separate heartbeat signal from cardiorespiratory signal either in frequency or in temporal domain. The measurements were performed simultaneously with a PC-based electrocardiogram to validate the heartbeat rate detection techniques. In conclusion, processing techniques used in this paper give accurate results

Investigation of the feasiblity of employing a radial turbine for a utility-scale supercritical CO₂ power cycle.

With the current growth rate of world population, comes a high demand on electric energy generation. Technological advancements in metallurgy, fuel conversion, heat transfer, and turbomachinery design allow the continuous dominating rule of fossil fuel energy resources and the expansion of non-renewable based power cycles. The challenges arising due to greenhouse gas emissions from fossil fuel combustion necessitate regulated policies to limit CO₂ emissions in particular. Design considerations and issues in power plants revolve around increasing efficiencies, reducing noise pollution and land footprint, while mitigating emissions. An example of advanced power configurations include the supercritical CO₂ cycle that has gained much interest in recent years due to its compact-size turbomachinery, increased efficiencies compared to other conventional steam or gas cycles, and its ability to be coupled with a wide range of heat sources. Another avant-garde technology is an oxy-combustion cycle that proves more favourable than the other carbon capture and storage routes of gasification and absorption. A proposed NET Power (Allam) cycle, which combines both technologies of using supercritical CO₂ conditions in an oxy-combustion gas-fired power plant, seems promising with claims of cycle efficiencies reaching 55%. However, the Allam cycle is still in a pre-mature phase due to the barriers that inhibit its full-scale development; challenges include the design of a high-pressure, high-temperature turbine which dictates cooling requirements, material considerations, and number of stages to name a few. A radial turbine, which generally has a simpler construction and fewer stages when compared to an axial turbine, is suggested as a superior candidate configuration for cycles of high fluid density. A thermodynamic analysis of a mid-range cycle similar to that proposed by NET Power is established while lowering the turbine inlet temperature to 900 C in order to remove cooling complications within the radial turbine passages. The cycle conditions are then considered for the design of a 100 MWth power scale turbine by using preliminary and higher fidelity methods. Two radial turbine designs are illustrated; the first, whilst not satisfying the cycle operating conditions, is used to showcase the detailed 1D design as well as the 2D and 3D analyses procedures followed during this work. A second 510 mm diameter turbine, running at 21,409 rpm, capable of operating within a 5% range of the required cycle conditions, is designed and presented. Results from computational fluid dynamics simulations indicate the loss mechanisms responsible for the low-end value of the turbine total-to-total efficiency which is 69.87%. Mechanical stress calculations show that the aerodynamic flow path of the rotor blades experience tolerable stress values, however a more detailed disc design is required to meet actual material constraints.PhD in Energy and Powe

Low Dimensionality in Gene Expression Data Enables the Accurate Extraction of Transcriptional Programs from Shallow Sequencing

A tradeoff between precision and throughput constrains all biological measurements, including sequencing-based technologies. Here, we develop a mathematical framework that defines this tradeoff between mRNA-sequencing depth and error in the extraction of biological information. We find that transcriptional programs can be reproducibly identified at 1% of conventional read depths. We demonstrate that this resilience to noise of “shallow” sequencing derives from a natural property, low dimensionality, which is a fundamental feature of gene expression data. Accordingly, our conclusions hold for ∼350 single-cell and bulk gene expression datasets across yeast, mouse, and human. In total, our approach provides quantitative guidelines for the choice of sequencing depth necessary to achieve a desired level of analytical resolution. We codify these guidelines in an open-source read depth calculator. This work demonstrates that the structure inherent in biological networks can be productively exploited to increase measurement throughput, an idea that is now common in many branches of science, such as image processing

Synergistic dual positive feedback loops established by molecular sequestration generate robust bimodal response

Feedback loops are ubiquitous features of biological networks and can produce significant phenotypic heterogeneity, including a bimodal distribution of gene expression across an isogenic cell population. In this work, a combination of experiments and computational modeling was used to explore the roles of multiple feedback loops in the bimodal, switch-like response of the Saccharomyces cerevisiae galactose regulatory network. Here, we show that bistability underlies the observed bimodality, as opposed to stochastic effects, and that two unique positive feedback loops established by Gal1p and Gal3p, which both regulate network activity by molecular sequestration of Gal80p, induce this bimodality. Indeed, systematically scanning through different single and multiple feedback loop knockouts, we demonstrate that there is always a concentration regime that preserves the system’s bimodality, except for the double deletion of GAL1 and the GAL3 feedback loop, which exhibits a graded response for all conditions tested. The constitutive production rates of Gal1p and Gal3p operate as bifurcation parameters because variations in these rates can also abolish the system’s bimodal response. Our model indicates that this second loss of bistability ensues from the inactivation of the remaining feedback loop by the overexpressed regulatory component. More broadly, we show that the sequestration binding affinity is a critical parameter that can tune the range of conditions for bistability in a circuit with positive feedback established by molecular sequestration. In this system, two positive feedback loops can significantly enhance the region of bistability and the dynamic response time