775 research outputs found

    Adaptive epidemic dissemination as a finite-horizon optimal stopping problem

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    Wireless ad hoc networks are characterized by their limited capabilities and their routine deployment in unfavorable environments. This creates the strong requirement to regulate energy expenditure. We present a scheme to regulate energy cost through optimized transmission scheduling in a noisy epidemic dissemination environment. Building on the intrinsically cross-layer nature of the adaptive epidemic dissemination process, we strive to deliver an optimized mechanism, where energy cost is regulated without compromising the network infection. Improvement of data freshness and applicability in routing are also investigated. Extensive simulations are used to support our proposal

    Near-infrared Fourier transform room-temperature photoluminescence of erbium complexes

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    A modified Fourier transform (FT) Raman bench spectrometer designed for the detection of weak light emission in the 800–1700 nm wavelength region has been used to demonstrate the advantages of FT spectroscopy for measuring near-infrared photoluminescence spectra of lanthanide complexes with a good resolution and very good sensitivity. This apparatus has been tested with an ultraviolet laser source (325 nm) on three standard erbium complexes. The 4I13/24I15/2 emission of tris-(acetylacetonato) (1,10 phenanthroline) erbium [Er(acac)3(phen)], tris-(4,4,4,-trifluoro-1-(2 thenoyl)-1,3-butenedione) (1,10 phenanthroline) erbium [Er(TTFA)3(phen)] and tris(8-hydroxyquinolinato) erbium [Erq3] has thus been recorded in solution and in the solid state and compared with literature. ©2003 American Institute of Physics

    Ultra-smooth lithium niobate micro-resonators by surface tension reshaping

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    Thermal treatment of micro-structured lithium niobate substrates at temperatures close to, but below the melting point, allows surface tension to reshape a preferentially melted surface zone [1] of the crystal to form ultra-smooth single crystal toroidal or spherical structures. Such structures, an example of which is shown in figure 1, are suitable for the fabrication of photonic micro-resonators with low scattering loss. The thermally treated material maintains its single crystal nature after the thermal treatment because the bulk remains solid throughout the process acting as seed during the recrystallization process which takes place during the cooling stage. The single crystal nature of the reshaped material has been verified by piezoresponse force microscopy, Raman spectroscopy and chemical etching. The inherent properties of lithium niobate crystals (optically nonlinear, piezoelectric and electro-optic) makes the resultant micro-resonator extremely suitable for sensing applications, for the production of micro-lasers (if doped with Er or Nd), for nonlinear frequency generation and finally for switching/modulation and tunable spectral filtering in optical telecommunications. The transformation of the initial surface micro-structures to the resulting resonator structure is a temperature dependent process as the surface tension acts on the surface melted layer of the crystal, Experimental investigation and modelling of the thermal treatment as well as investigation of the performance of these microresonators is underway to establish full control of the fabrication process for practical applications

    A phytosociological survey of aquatic vegetation in the main freshwater lakes of Greece. Vegetation

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    Zervas D, Tsiripidis I, Bergmeier E, Tsiaoussi V (2020) A phytosociological survey of aquatic vegetation in the main freshwater lakes of Greece. Vegetation Classification and Survey 1: 53-75. https://doi.org/10.3897/VCS/2020/48377This study aims to contribute to the knowledge of European freshwater lake ecosystems with updated and new information on aquatic plant communities, by conducting national-scale phytosociological research of freshwater lake vegetation in Greece. Moreover, it investigates the relationship between aquatic plant communities and lake environmental parameters, including eutrophication levels and hydro-morphological conditions. Study area: Lakes in Greece, SE Europe

    Effect of dietary protein source on piglet meat quality characteristics

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    An experiment was conducted to examine the effects of different dietary protein sources (soybean meal vs whey protein) on piglet meat quality characteristics. Eighteen castrated male Large White × Duroc × Landrace piglets were randomly assigned to 2 groups. Piglets were kept in individual metabolic cages and fed ad libitum over a period of 38 days the following 2 diets: diet SB, which was formulated to meet the nutrient requirements of piglets using soybean meal as the main crude protein source and diet WP, where SB was totally replaced by a mixture of whey proteins on equal digestible energy and crude protein basis. At the end of the experiment, piglets were weighed and slaughtered. After overnight chilling, samples of Longissimus dorsi muscle were taken and were used for meat quality measurements.         No significant differences were observed in the values of pH, colour, water holding capacity, shear force and intramuscular fat content of L. dorsi muscle between the dietary treatments. Measurement of lipid oxidation values showed that dietary supplementation with different protein sources did not influence meat antioxidant properties during refrigerated storage. The SB piglets had lower 14:0 (P<0.01) and higher 18:3n-3 (P<0.001) levels in intramuscular fat in comparison with WP piglets. However, these changes were attributed to background differences in the dietary FA profile and not to a direct protein source effect. The results of this preliminary study indicate that the examined dietary protein sources (soybean meal or whey protein) do not have a significant effect on meat quality characteristics of piglets

    Global and Regional Sea Level Rise Scenarios for the United States

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    The Sea Level Rise and Coastal Flood Hazard Scenarios and Tools Interagency Task Force, jointly convened by the U.S. Global Change Research Program (USGCRP) and the National Ocean Council (NOC), began its work in August 2015. The Task Force has focused its efforts on three primary tasks: 1) updating scenarios of global mean sea level (GMSL) rise, 2) integrating the global scenarios with regional factors contributing to sea level change for the entire U.S. coastline, and 3) incorporating these regionally appropriate scenarios within coastal risk management tools and capabilities deployed by individual agencies in support of the needs of specific stakeholder groups and user communities. This technical report focuses on the first two of these tasks and reports on the production of gridded relative sea level (RSL, which includes both ocean-level change and vertical land motion) projections for the United States associated with an updated set of GMSL scenarios. In addition to supporting the longer-term Task Force effort, this new product will be an important input into the USGCRP Sustained Assessment process and upcoming Fourth National Climate Assessment (NCA4) due in 2018. This report also serves as a key technical input into the in-progress USGCRP Climate Science Special Report (CSSR)

    Effects of olive pulp addition to broiler diets on performance, selected biochemical parameters and antioxidant enzymes

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    H παραγωγή ελαιόλαδου δημιουργεί ορισμένα υποπροϊόντα τα οποία μπορούν να χρησιμοποιηθούν στη διατροφή των ζώων. Αυτά τα υποπροϊόντα περιέχουν αρκετές πολυφαινολικές ενώσεις που ενδέχεται να παρουσιάζουν αντιοξειδωτικές ιδιότητες. Η παρούσα μελέτη σχεδιάστηκε για να αξιολογήσει την επίδραση της προσθήκης πάστας ελαιόκαρπου στο σιτηρέσιο ορνιθίων κρεοπαραγωγής στην ανάπτυξη, στην απόδοση σε σφάγιο και στην ενεργότητα ορισμένων αντιοξειδωτικών ενζύμων. Διακόσιοι (200), νεοσσοί κρεοπαραγωγής Cobb 500, ηλικίας μιας ημέρας, εκτράφηκαν για συνολικά 42 ημέρες. Υπήρξαν 4 διατροφικές επεμβάσεις. Στην επέμβαση T1 δεν προστέθηκε πάστα ελαιόκαρπου στο εναρκτήριο, ανάπτυξης και τελικό σιτηρέσιο. Στην επέμβαση Τ2, η πάστα ελαιόκαρπου προστέθηκε στο εναρκτήριο, ανάπτυξης και τελικό σε επίπεδο 0, 2,5 και 5% αντιστοίχως. Στην επέμβαση Τ3, η πάστα ελαιόκαρπου προστέθηκε στα τρία σιτηρέσια σε επίπεδο 0, 5 και 5% αντιστοίχως, ενώ στην επέμβαση T4 σε επίπεδο 0, 5 και 8% αντιστοίχως. Μελετήθηκε η ανάπτυξη, η απόδοση σε σφάγιο και ένας αριθμός βιοχημικών παραμέτρων. Η oλευρωπεΐνη και η υδροξυτυροσόλη ανιχνεύτηκαν στην πάστα ελαιόκαρπου σε επίπεδα 952 και 216 mg/kg αντιστοίχως. Τα ορνίθια αναπτύχθηκαν καλά και δεν παρατηρήθηκαν διαφορές μεταξύ των επεμβάσεων στο τελικό σωματικό βάρος, την απόδοση σε σφάγιο, την ολική αντιοξειδωτική ικανότητα και την ενεργότητα των αντιοξειδωτικών ενζύμων. Εφαρμογή της διακριτικής ανάλυσης έδειξε ότι τα δείγματα διακρίνονται βάση του επιπέδου προσθήκης πάστας ελαιόκαρπου. Τα δείγματα των επεμβάσεων Τ2 και Τ3 εντοπίστηκαν στο κέντρο του διαγράμματος απομακρυσμένα από τις άλλες επεμβάσεις παρουσιάζοντας υψηλές τιμές σε απόδοση σε σφάγιο, αναλογία βάρους στήθους προς σωματικό βάρος και ενεργότητα των περισσοτέρων αντιοξειδωτικών ενζύμων. Συμπερασματικά, η πάστα ελαιόκαρπου μπορεί να χρησιμοποιηθεί στα σιτηρέσια ορνιθίων κρεοπαραγωγής έως 5% και μελλοντικές μελέτες σε πραγματικές συνθήκες εκτροφής ίσως αναδείξουν περαιτέρω τις θετικές επιδράσεις αυτού στην απόδοση και αντιοξειδωτική προστασία των ορνιθίων.Olive oil production generates various by-products that can be used in animal nutrition. These by-products contain several polyphenolic compounds that may exhibit antioxidant properties. The present study was designed to evaluate the effects of adding olive pulp to the feed on broiler performance, carcass yield and antioxidant enzymes. Two hundred (200), as hatched, day-old, Cobb 500 broilers were reared in total for 42 days. There were 4 dietary treatments. In T1 treatment, no olive pulp was added to starter, grower and finisher diet. In T2 treatment, olive pulp was added to starter, grower and finisher diet at a level of 0, 2.5 and 5% respectively. In T3 treatment, olive pulp was added to starter, grower and finisher diet at a level of 0, 5 and 5% respectively. In T4 treatment, olive pulp was added to starter, grower and finisher diet at a level of 0, 5 and 8% respectively. Performance, carcass yield and a number of biochemical parameters were examined. Oleuropein and hydroxytyrosol were present in the olive pulp at 952 and 216 mg/kg respectively. Broilers performed well and no differences were observed between treatments on final body weight, carcass yield, total antioxidant activity and expression of selected antioxidant enzymes. Discriminant analysis was further applied and revealed that samples clustered according to added level of olive pulp. Samples from broilers fed T2 and T3 diet were located in the middle of the plot away from other treatments exhibiting high values of carcass, breast yield and most of the antioxidant enzyme activities. In conclusion, olive pulp can be used up to 5% in diets of broilers and future studies conducted on-farm conditions may pronounce its impact on growth performance and antioxidant potential

    Breakfast glycaemic index and exercise: combined effects on adolescents' cognition

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    The aim of the present study was to examine the combined effects of breakfast glycaemic index (GI) and a mid-morning bout of exercise on adolescents’ cognitive function. Participants were randomly allocated to a high or low GI breakfast group in a mixed research design, where each participant completed two experimental trials (exercise and resting). Forty-two adolescents (12.4±0.5 years old), undertook a bout of exercise (ten repeats of level one of the multi-stage fitness test; exercise trial) or continued to rest (resting trial) following consumption of either a high or low GI breakfast. A battery of cognitive function tests (visual search test, Stroop test and Sternberg paradigm) was completed 30 min before and 45 min following the exercise. Average heart rate during exercise was 170±15 beats.min-1. On the complex level of the Stroop test, response times improved across the morning following the low GI breakfast on both the exercise and resting trials, though the improvement was greatest on the exercise trial. However, response times only improved on the resting trial following the high GI breakfast (p = 0.012). On the 5 letter level of the Sternberg paradigm, response times improved across the morning following the low GI breakfast (regardless of exercise) and only on the exercise trial following the high GI breakfast (p = 0.019). The findings of the present study suggest that the combined effects of breakfast GI and exercise in adolescents depend upon the component of cognitive function examined. A low GI breakfast and mid-morning bout of exercise were individually beneficial for response times on the Sternberg paradigm, whereas they conferred additional benefits for response times on the Stroop test
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