Ecohydrological characterization of the Nyando wetland, Lake Victoria, Kenya: A State of System (SoS) analysis

Lake Victoria floodplain wetlands have a complex hydrological setting characterized by transition from a terrestrial to an aquatic environment. A state-of-system (SoS) analysis was carried out in a papyrus dominated wetland in the Nyando River Delta, on the eastern shores of Lake Victoria, Kenya, to characterize and provide data for detailed ecohydrological studies. The objectives of the study were to: (1) determine the spatio- temporal changes in the wetland evolution and (2) analyze the main hydrological factors that have influenced wetland evolution. Multi-temporal dry-season Landsat MSS, Landsat TM and Landsat ETM+ imagery covering Nyando Wetland and its surrounding area were processed and analyzed to generate time series polygon and polyline maps of the wetland and river. Results show that the wetland increased in size from 5,925 ha in 1950 to 9,925 ha in 1973, and declined to 4,527 ha in 2008. In the last 60 years, Nyando River has migrated in a general eastward direction. Time series hydrological data (1950-2009) were statistically tested for homogeneity  using the Spearman’s rank test for linear trends, Pettit test and Standard Normal Homogeneity test (SNHT) for change point analysis, and split-record tests performed for variance (F-test) and mean (t-test). In addition, data were analyzed using descriptive statistics and frequency analyses. Statistical test results show that the hydrological data series were homogeneous. Results of change point analyses indicate that total annual rainfall in Nyando declined in 1979, while the mean annual discharge for Nyando River and Lake Victoria levels had significant upward shifts in 1961. The decadal mean discharges varied significantly over time and increased by 80% from 11.45 m3/s observed in the 1950-1961 subset, reducing by 11.4 and 21.9% in the next two decadal sub-sets, before rising by 35.0% in 1990s and dropping by 24.0% in the last decade. The decadal mean annual lake levels increased from 1134.0 to 1135.43 m in the 1951-1961 and 1962-1972 and remained above the longterm mean of 1135.0 m for 43 years since 1962 before dropping drastically by 1.4 m to an average of 1134 m/year in 2005-2009. The highest recorded lake level at Kisumu Station was 1136.2 m in 1964 after increasing by 2.5 m from 1961. Discharge data exhibit trimodal seasonal patterns, while the lake levels had two peaks. The lake levels are more sensitive to direct lake rainfall. Changes in the Nyando wetland area are linked to the seasonal and episodic flood and drought events coupled with anthropogenic activities (regulation of lake levels, modification of river including cut-off meanders, river training and construction of dykes, drainage of wetland for cultivation, settlement and livestock grazing, abstraction of water for irrigation). A combination of these hydrological and human factors is the main cause of the Nyando Wetland evolution. If the land use trend continues unabated, then the increase in papyrus losses will pose a big challenge to the ecological functioning of the wetland and its support to sustaining community livelihoods.Key words: Nyando Wetland, River, ecohydrology, Lake Victoria

Calibration of centre-of-mass energies at LEP 2 for a precise measurement of the W boson mass

The determination of the centre-of-mass energies for all LEP 2 running is presented. Accurate knowledge of these energies is of primary importance to set the absolute energy scale for the measurement of the W boson mass. The beam energy between 80 and 104 GeV is derived from continuous measurements of the magnetic bending field by 16 NMR probes situated in a number of the LEP dipoles. The relationship between the fields measured by the probes and the beam energy is defined in the NMR model, which is calibrated against precise measurements of the average beam energy between 41 and 61 GeV made using the resonant depolarisation technique. The validity of the NMR model is verified by three independent methods: the flux-loop, which is sensitive to the bending field of all the dipoles of LEP; the spectrometer, which determines the energy through measurements of the deflection of the beam in a magnet of known integrated field; and an analysis of the variation of the synchrotron tune with the total RF voltage. To obtain the centre-of-mass energies, corrections are then applied to account for sources of bending field external to the dipoles, and variations in the local beam energy at each interaction point. The relative error on the centre-of-mass energy determination for the majority of LEP 2 running is 1.2 x 10^{-4}, which is sufficiently precise so as not to introduce a dominant uncertainty on the W mass measurement.Comment: 79 pages, 45 figures, submitted to EPJ

Orange jasmine as a trap crop to control Diaphorina citri

[EN] Novel, suitable and sustainable alternative control tactics that have the potential to reduce migration of Diaphorina citri into commercial citrus orchards are essential to improve management of huanglongbing (HLB). In this study, the effect of orange jasmine (Murraya paniculata) as a border trap crop on psyllid settlement and dispersal was assessed in citrus orchards. Furthermore, volatile emission profiles and relative attractiveness of both orange jasmine and sweet orange (Citrus¿×¿aurantium L., syn. Citrus sinensis (L.) Osbeck) nursery flushes to D. citri were investigated. In newly established citrus orchards, the trap crop reduced the capture of psyllids in yellow sticky traps and the number of psyllids that settled on citrus trees compared to fallow mowed grass fields by 40% and 83%, respectively. Psyllids were attracted and killed by thiamethoxam-treated orange jasmine suggesting that the trap crop could act as a `sink¿ for D. citri. Additionally, the presence of the trap crop reduced HLB incidence by 43%. Olfactometer experiments showed that orange jasmine plays an attractive role on psyllid behavior and that this attractiveness may be associated with differences in the volatile profiles emitted by orange jasmine in comparison with sweet orange. Results indicated that insecticide-treated M. paniculata may act as a trap crop to attract and kill D. citri before they settled on the edges of citrus orchards, which significantly contributes to the reduction of HLB primary spread.This work was supported by Fund for Citrus Protection (Fundecitrus) and by Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) (Proc. 2015/07011-3). We thank Moacir Celio Vizone, Felipe Marinho Martini and Joao Pedro Ancoma Lopes for technical support with experiments. Furthermore, we thank Cambuhy Agricola Ltda. and University of Araraquara (Uniara) for providing the areas in which the field experiments were performed. 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Crop Prot. 105, 10–15 (2018).Miranda, M. P. et al. Processed kaolin affects the probing and settling behavior of Diaphorina citri (Hemiptera: Liviidae). Pest Manag. Sci. 74, 1964–1972 (2018).Kobori, Y., Nakata, T., Ohto, Y. & Takasu, F. Dispersal of adult Asian citrus psyllid, Diaphorina citri Kuwayama (Homoptera: Psyllidae), the vector of citrus greening disease, in artificial release experiments. Appl. Entomol. Zool. 46, 27–30 (2011).Sétamou, M. et al. Diurnal patterns of flight activity and effects of light on host finding behavior of the Asian citrus psyllid. J. Insect Behav. 25, 264–276 (2012).Wenninger, E. J., Stelinski, L. L. & Hall, D. G. Roles of olfactory cues, visual cues, and mating status in orientation of Diaphorina citri Kuwayama (Hemiptera: Psyllidae) to four different host plants. Environ. Entomol. 38, 225–234 (2009).Miranda, M. P., Dos Santos, F. L., Felippe, M. R., Moreno, A. & Fereres, A. 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Effects of cereal borders, admixture with cereals and plant density on the spread of bean yellow mosaic potyvirus into narrow‐leafed lupins (Lupinus angustifolius). Ann. Appl. Biol. 122, 501–518 (1993).Beloti, V. H., Alves, G. R., Coletta-Filho, H. D. & Yamamoto, P. T. The Asian citrus psyllid host Murraya koenigii is immune to citrus huanglongbing pathogen ‘Candidatus Liberibacter asiaticus’. Phytopathology 108, 1089–1094 (2018).Walter, A. J., Duan, Y. & Hall, D. G. Titers of ‘Ca. Liberibacter asiaticus’ in Murraya paniculata and Murraya-reared Diaphorina citri are much lower than in Citrus and Citrus-reared psyllids. HortScience 47, 1449–1452 (2012).Walter, A. J., Hall, D. G. & Duan, Y. P. Low incidence of ‘Candidatus Liberibacter asiaticus’ in Murraya paniculata and associated Diaphorina citri. Plant Dis. 96, 827–832 (2012).Ammar, E.-D. D., Ramos, J. E., Hall, D. G., Dawson, W. O. & Shatters, R. G. Acquisition, replication and inoculation of Candidatus Liberibacter asiaticus following various acquisition periods on huanglongbing-infected citrus by nymphs and adults of the Asian citrus psyllid. PLoS One 11, e0159594 (2016).Inoue, H. et al. Enhanced proliferation and efficient transmission of Candidatus Liberibacter asiaticus by adult Diaphorina citri after acquisition feeding in the nymphal stage. Ann. Appl. Biol. 155, 29–36 (2009).Pelz-Stelinski, K. S., Brlansky, R. H., Ebert, T. A. & Rogers, M. E. Transmission parameters for Candidatus Liberibacter asiaticus by Asian citrus psyllid (Hemiptera: Psyllidae). J. Econ. Entomol. 103, 1531–1541 (2010).Canale, M. C. et al. Latency and persistence of ‘Candidatus Liberibacter asiaticus’ in its psyllid vector, Diaphorina citri (Hemiptera: Liviidae). Phytopathology 107, 264–272 (2017).Li, W., Hartung, J. S. & Levy, L. Quantitative real-time PCR for detection and identification of Candidatus Liberibacter species associated with citrus huanglongbing. J. Microbiol. Methods 66, 104–115 (2006).Nakata, T. Effectiveness of micronized fluorescent powder for marking citrus psyllid. Diaphorina citri. Appl. Entomol. Zool. 43, 33–36 (2008).Tomaseto, A. F. et al. Environmental conditions for Diaphorina citri Kuwayama (Hemiptera: Liviidae) take-off. J. Appl. Entomol. 142, 104–113 (2018).Paris, T. M., Croxton, S. D., Stansly, P. A. & Allan, S. A. Temporal response and attraction of Diaphorina citri to visual stimuli. Entomol. Exp. Appl. 155, 137–147 (2015).Zanardi, O. Z. et al. Putative sex pheromone of the Asian citrus psyllid, Diaphorina citri, breaks down into an attractant. Sci. Rep. 8, 455 (2018).Metsalu, T. & Vilo, J. ClustVis: A web tool for visualizing clustering of multivariate data using Principal Component Analysis and heatmap. Nucleic Acids Res. 43, W566–W570 (2015).Fournier, D. A. et al. 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Fluid and particle passage in three duiker species

Ruminants are characterised by two different types of reticulorumen (RR) physiology. ‘Cattle-type’ ruminants have, amongst other features such as RR contents stratification and a heterogenous intraruminal papillation, a distinct difference between the mean retention time (MRT) of small particles and fluids (the ratio is called the selectivity factor, SF). ‘Moose-type’ ruminants have RR contents that are less stratified, a more homogenous intraruminal papillation and low SFs, indicating less difference in the MRT of small particles and fluids. To date, physiological data indicating a ‘moose-type’ physiology have only been measured in giraffids and Odocoilean cervids, raising the question whether it is limited to these taxonomic groups only. Here, we measured MRTs of fluids and particles in five duikers (Bovidae, Cephalophinae) from three species (Sylvicapra grimmia, Cephalophus monticola and Cephalophus sylvicultor) and found SFs in the RR of 1.27±0.18 — well within the range of these other browsers. These results are the first physiological indication that a ‘moose-type’ physiology may also occur in bovid species and thus might represent a true convergent adaptation

Nutritional content of savanna plant foods: implications for browser/grazer models of ungulate diversification

Models of herbivore diversification rely heavily on adaptations that reflect the nutritional quality of foods consumed. In particular, browsers and grazers are expected to show dichotomous adaptations to deal with high quality (concentrate) browse-based and poor quality grass-based diets, respectively. In this study, we test the widespread assumption that browse represents a higher quality food source than grass. We analyzed plants from a South African savanna, collected over one dry and one wet season across several habitat types, for percent nitrogen (%N), neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) to compare variations in nutritional value of different food types. Results show consistently higher %N and lower NDF and ADF of tree foliage and forbs compared to monocots, but the former have consistently higher ADL, implying a higher fiber digestibility in grass compared with browse. Some fruit species have a high NDF and ADL content, implying poorer nutritional value than is commonly assumed. Our findings are in agreement with several other studies depicting relatively poor digestibility of browse (tree foliage and fruit) compared to grass. Reference to browse as high quality foods is therefore misleading, and models of herbivory that rest on this assumption require revision. The more efficient fiber digestibility recorded in grazers compared to browsers cannot be treated as an adaptation to poor quality diets, but rather to maximize benefits of higher fiber digestibility of grass. Spatio-seasonal variations in plant nutritional seem to reflect seasonal and spatial diet changes expected for grazers and intermediate (mixed) feeders. We propose that future studies require further detail on variations in diet, diet quality, and digestive efficiency to properly understand mechanisms of adaptation

FISH protocol for Myotonic Dystrophy type 1 cells

International audienc

Calibration of centre-of-mass energies at LEP1 for precise measurements of Z properties

The determination of the centre-of-mass energies from the LEP1 data for 1993, 1994 and 1995 is presented Accurate knowledge of these energies is crucial in the measurement of the Z resonance parameters The improved understanding of the LEP energy behaviour accumulated during the 1995 energy scan is detailed while the 1993 and 1994 measurements are revised. For 1993 these supersede the previously published values. Additional instrumentation has allowed the detection of an unexpectedly large energy rise during physics fills. This new effect is accommodated in the modelling of the beam-energy in 1995 and propagated to the 1993 and 1994 energies. New results are reported on the magnet temperature behaviour which constitutes one of the major corrections to the average LEP energy. The 1995 energy scan took place in conditions very different from the previous years. In particular the interaction-point specific corrections to the centre-of-mass energy in 1995 are more complicated than previously, these arise from the modified radiofrequency-system configuration and from opposite-sign vertical dispersion induced by the bunch-train mode of LEP operation. Finally an improved evaluation of the LEP centre-of-mass energy spread is presented. This significantly improves the precision on the Z width