Non-destructive plant health sensing using absorption spectroscopy

The sensor group of the 1988 EGM 4001 class, working on NASA's Controlled Ecological Life Support Systems (CELSS) project, investigated many different plant health indicators and the technologies used to test them. The project selected by the group was to measure chlorophyll levels using absorption spectroscopy. The spectrometer measures the amount of chlorophyll in a leaf by measuring the intensity of light of a specific wavelength that is passed through a leaf. The three wavelengths of light being used corresponded to the near-IR absorption peaks of chlorophyll a, chlorophyll b, and chlorophyll-free structures. Experimentation showed that the sensor is indeed measuring levels of chlorophyll a and b and their changes before the human eye can see any changes. The detector clamp causes little damage to the leaf and will give fairly accurate readings on similar locations on a leaf, freeing the clamp from having to remain on the same spot of a leaf for all measurements. External light affects the readings only slightly so that measurements may be taken in light or dark environments. Future designs and experimentation will concentrate on reducing the size of the sensor and adapting it to a wider range of plants

The Impact of Visualization and Expectation on Tourists’ Emotion and Satisfaction at the Destination

As tourist satisfaction is a clear goal in the tourism industry it is important to examine the consumers’ psychological process during the pre or post consumption experience including visualization, expectation, emotion and satisfaction of the destination. The current study seeks to show how novelty seekers who engage in visualization create expectations about a destination, and how it can enhance their positive arousal and emotion about the overall trip, ultimately leading to satisfaction with the destination. Managers should recognize how satisfaction, motivation, visualization, expectation, arousal and emotion are associated in order to provide a satisfying experience to tourist

Cell migration directionality and speed are independently regulated by RasG and Gβ in Dictyostelium cells in electrotaxis.

Motile cells manifest increased migration speed and directionality in gradients of stimuli, including chemoattractants, electrical potential and substratum stiffness. Here, we demonstrate that Dictyostelium cells move directionally in response to an electric field (EF) with specific acceleration/deceleration kinetics of directionality and migration speed. Detailed analyses of the migration kinetics suggest that migration speed and directionality are separately regulated by Gβ and RasG, respectively, in EF-directed cell migration. Cells lacking Gβ, which is essential for all chemotactic responses in Dictyostelium, showed EF-directed cell migration with the same increase in directionality in an EF as wild-type cells. However, these cells failed to show induction of the migration speed upon EF stimulation as much as wild-type cells. Loss of RasG, a key regulator of chemoattractant-directed cell migration, resulted in almost complete loss of directionality, but similar acceleration/deceleration kinetics of migration speed as wild-type cells. These results indicate that Gβ and RasG are required for the induction of migration speed and directionality, respectively, in response to an EF, suggesting separation of migration speed and directionality even with intact feedback loops between mechanical and signaling networks

Interplay between spin-orbit coupling and van Hove singularity in the Hund's metallicity of Sr2_2RuO4_4

We investigate the dynamical properties of Sr$_2$RuO$_4$ at zero and very low temperature using density functional theory plus dynamical mean-field theory with an exact diagonalization solver. By considering rotationally invariant local interaction, we examine how Hund's coupling and spin-orbit coupling affect the correlated nature of the system. In the absence of Hund's coupling, the system shows a Fermi liquid behavior over the entire range of temperatures we consider. We confirm that the Fermi liquid persists at zero temperature even with nonzero Hund's coupling; however, at sufficient temperatures Hund's coupling significantly reduces the Fermi liquid regime and the system evolves into a typical Hund's metal. At the bare electronic occupancy of Sr$_2$RuO$_4$ ($t_{2g}^4$), a stronger Hund's metallicity accompanies a larger long-time correlator. Remarkably, electron doping further destabilizes the Fermi liquid even though the long-time correlator and magnetic fluctuations decrease upon doping. This suppression of the Fermi liquid is driven by the van Hove singularity above the Fermi level in Sr$_2$RuO$_4$, combined with an enhanced Van Vleck susceptibility by spin-orbit coupling. Such findings point to the important role that electronic structure plays in the behavior of Hund's metals, in addition to magnetic fluctuations.Comment: 7 pages, 4 figure

A Case Study of Solar Warming and Subsequent Mixing in the Arctic Upper Ocean for the 2011 Spring-Summer Transition

Autonomous buoys were deployed in 2011 in the central Arctic: An Ice-Tethered Profiler (ITP) and Ice Mass Balance (IMB) buoys were deployed in the Makarov basin; a Polar Ocean Profiling System (POPS) and Ice Thickness (Ice-T) buoy were deployed on the Eurasian Basin. The two different sites were approximately 70km apart. We compare the two different drifting stations to investigate spatial variability associated with heat fluxes near the ice base and spatial water property variability within the surface mixed layer. Our case study follows Vivier et al. (2016) who found the early basal melt onset at the Eurasian Basin site. Focusing on the basal melt onset, we ask the following questions: (1) Do spatial variations in the upper ocean drive the different timing of the basal melt onset? (2) How is the basal melt onset timing affected by these spatial variations? We found spatial differences in upper water properties and melt onset during the spring-summer transition. The freshening of surface water at the Eurasian Basin site happens about 20 days earlier than the Makarov Basin site. We identified low ice speed is associated with warming and freshening near the surface, suggesting accumulation of absorbed solar radiation heat near the ice is mixed deeper after quiescent periods. Subsequent mixing affects the vertical heat flux between the water above and below. During surface layer freshening, variability in lead opening and ice motion controls the spatial variability in the mixed layer as well as the basal melt associated with heat flux from the upper ocean to the bottom of the sea ice. At non-quiescent times, in spring, heat flux is related to deeper stratification

Patients’ subjective well-being: determinants and its usage as a metric of healthcare service quality

It is commonly suggested that patients’ subjective well-being (SWB) can be affected by pre-treatment conditions and treatment experiences, and hence SWB can be used to measure and improve healthcare quality. With data collected in a hospital in the UK (N = 446), we investigated the determinants of patients’ SWB and evaluated its use in healthcare research. Our findings showed strong relationships between pre-treatment conditions and patients’ SWB: anxiety and depression negatively predicted SWB across all three domains, mobility positively predicted the life satisfaction and happiness domains, while the ability to self care and pain and discomfort also predicted SWB in some domains. In contrast, patients’ satisfaction with the treatment only played minor roles in determining SWB, much less so the characteristics of their nurses. The general lack of associations between treatment experiences and patient’s SWB highlighted the challenges of using SWB to measure healthcare quality and inform policy making

Automatic generation of equations of motion for multibody system in discrete event simulation framework

AbstractIn this paper, the development of a simulation program that can automatically generate equations of motion for mutibody systems in the discrete event simulation framework is presented. The need to analyze the dynamic response of mechanical systems that are under event triggered conditions is increasing. General mechanical systems can be defined as multibody systems that are collections of interconnected rigid bodies, consistent with various types of joints that limit the relative motion of pairs of bodies. For complex multibody systems, a systematic approach is required to efficiently set up the mathematical models. Therefore, a dynamics kernel was developed to automatically generate the equations of motion for multibody systems based on multibody dynamics. The developed dynamics kernel also provides the numerical solver for the dynamic analysis of multibody systems. The general multibody dynamics kernel cannot deal with discontinuous state variables, event triggered conditions, and state triggered conditions, though. To enable it to deal with multibody systems in discontinuous environments, the multibody dynamics kernel was integrated into a discrete event simulation framework, which was developed based on the discrete event system specification (DEVS) formalism. DEVS formalism is a modular and hierarchical formalism for modeling and analyzing systems under event triggered conditions, which are described by discontinuous state variables. To verify the developed program, it was applied to an block-lifting and transport simulation, and dynamic analysis of the system is carried out