9,837 research outputs found

    Plant canopy shape and the influences on UV exposures to the canopy

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    The solar spectra at selected sites over hemispherical, conical and pinnacle plant canopy models has been evaluated with a dosimetric technique. The irradiance at the sites varies by up to a factor of 0.31 compared to the irradiance on a horizontal plane. The biologically effective (UVBE) exposures evaluated with the dosimetric technique at sites over the plant canopy are up to 19% of that on a horizontal plane. Compared to a spectroradiometer, the technique provides a more practicable method of measuring the UVBE exposures at multiple sites over a plant canopy. Usage of a dosimeter at one site to provide the exposures at that site for different sun angles introduces an error of more than 50%. Knowledge of the spectra allowed the UV and UVBE exposures to be calculated at each site along with the exposures to the entire canopies. These were dependent on the sun angle and the canopy shape. For plant damage, the UVBE was a maximum of about 1.4 mJ cm-2/min. Compared to the hemispherical canopy, the UVBE exposure for generalised plant damage was 45% less for the pinnacle canopy and 23% less for the conical canopy. The canopy exposures could not be determined from measurements of the ambient exposure

    Self-Lensing Models of the LMC

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    All of the proposed explanations for the microlensing events observed towards the LMC have difficulties. One of these proposed explanations, LMC self-lensing, which invokes ordinary LMC stars as the long sought-after lenses, has recently gained considerable popularity as a possible solution to the microlensing conundrum. In this paper, we carefully examine the set of LMC self-lensing models. In particular, we review the pertinent observations made of the LMC, and show how these observations place limits on such self-lensing models. We find that, given current observational constraints, no purely LMC disk models are capable of producing optical depths as large as that reported in the MACHO collaboration 2-year analysis. Besides pure disk, we also consider alternate geometries, and present a framework which encompasses the previous studies of LMC self-lensing. We discuss which model parameters need to be pushed in order for such models to succeed. For example, like previous workers, we find that an LMC halo geometry may be able to explain the observed events. However, since all known LMC tracer stellar populations exhibit disk-like kinematics, such models will have difficulty being reconciled with observations. For SMC self-lensing, we find predicted optical depths differing from previous results, but more than sufficient to explain all observed SMC microlensing. In contrast, for the LMC we find a self-lensing optical depth contribution between 0.47e-8 and 7.84e-8, with 2.44e-8 being the value for the set of LMC parameters most consistent with current observations.Comment: 20 pages, Latex, 14 figures, submitted to Ap

    reconfigurable inspection robot for industrial applications

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    Abstract The power generation industry, due to its importance in both general public and industrial applications, requires high standard of reliability. In the electrical power generation processes, the inspection and the adequate maintenance of the power generators are extremely important. Currently these inspection procedures are performed by dismounting the generators after a predetermined amount of operating hours. Due to the huge size and the complexity of such machines, these operations other than being time-consuming are sometimes source of mechanical and electrical damages. Furthermore, several analyses are carried on by use of manual instrumentation operated by expert workers. Consequently, a series of important tests and structural analyses other than being very expensive are highly subjective and could lack on repeatability and reliability. Moreover, not all the results of these analyses are logged or electronically stored. Following the current trend of automation under the Industry 4.0 framework, an automated robotic vehicle has been designed with the aim of addressing the above-mentioned issues. The main features of such robot are the small dimensions, a magnetic coupling that gives the possibility to move on ferromagnetic surfaces, a reliable mechanical assembly and a wide reconfigurability in terms of mechanical add-ons and plug-and-play sensors. The housed sensors could be optical or IR cameras, ultrasonic scanner, surface analyzer, eddy currents detectors and even more. The tests conducted so far in realistic environments show that the presented system can be used to perform standard and reproducible inspections of complex machines like power generators. Moreover, due to its reconfigurability this vehicle can easily extend its range of application and be used in the inspection of other machines and infrastructures such as windmill blade, cranes, bridges beams, vessels and similar

    The prognostic significance of beta human chorionic gonadotrophin and its metabolites in women with cervical carcinoma

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    AIMS: To examine long term survival of women with primary and recurrent cervical carcinoma in relation to (1) excretion of beta-core (a urinary metabolite of beta human chorionic gonadotrophin (beta hCG)) and (2) beta hCG immunostaining of the tumours, to determine the suitability of these markers for assessing prognosis. METHODS: This was a prospective observational study undertaken in a gynaecological oncology centre: 57 women with primary cervical cancer and 42 with recurrent disease were recruited between January 1990 and September 1992. Kaplan-Meier survival analysis with the log rank test was used to assess survival differences with survival rate given per year of follow up. RESULTS: In primary disease, the four year survival for the beta-core negative group was 79%, compared with 14% for the beta-core positive group (p = 0.001). This was still significant for early stage disease or squamous lesions alone. In recurrent disease, beta-core positivity was not prognostically significant. Immunohistochemistry was of no prognostic significance in either group. CONCLUSIONS: beta-core excretion appears to be useful in assessing prognosis of primary cervical cancer but not of recurrent disease. A large prospective study of urinary beta-core in early stage cervical cancer is needed to determine whether it can be used as an index for modifying treatment

    Observational Constraints on General Relativistic Energy Conditions, Cosmic Matter Density and Dark Energy from X-Ray Clusters of Galaxies and Type-la Supernovae

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    New observational constraints on the cosmic matter density Ωm and an effectively redshift-independent equation of state parameter wx of the dark energy are obtained while simultaneously testing the strong and null energy conditions of general relativity on macroscopic scales. The combination of REFLEX X-ray cluster and type-Ia supernova data shows that for a flat Universe the strong energy condition might presently be violated whereas the null energy condition seems to be fulfilled. This provides another observational argument for the present accelerated cosmic expansion and the absence of exotic physical phenomena related to a broken null energy condition. The marginalization of the likelihood distributions is performed in a manner to include a large fraction of the recently discussed possible systematic errors involved in the application of X-ray clusters as cosmological probes. This yields for a flat Universe, Ωm = 0.29+0.08 and wx = −0.95+0.30 (1σ errors without −0.12 −0.35 cosmic variance). The scatter in the different analyses indicates a quite robust result around wx = −1, leaving little room for the introduction of new energy components described by quintessence-like models or phantom energy. The most natural interpretation of the data is a positive cosmological constant with wx = −1 or something like it
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