Abstract. This work investigates recent changes in precipitation patterns manifested in long annual and monthly precipitation time series recorded in Portugal. The dataset comprises records from 14 meteorological stations scattered over mainland Portugal and the Portuguese North Atlantic Islands of Madeira and Azores; some of the time series date back to the 19th century. The data were tested for trends using the Mann-Kendall non-parametric test and Sen's non-parametric method, searching both for full monotonic trends over the record period and for partial trends. Results provide no evidence for rejecting the null hypothesis of no trend in annual precipitation, when a monotonic linear model was used. Nevertheless, the analyses of 50 years' moving averages showed an increase over time, in the recent past, for many of the series in mainland Portugal and the Islands. For the longest time series this behaviour was preceded by a decrease over time. The analyses of partial trends in the time series suggested a sequence of alternately decreasing and increasing trends in annual and monthly precipitation, which are sometimes statistically significant. The trend changing points were identified.
12 pags., 6 figs., 4 tabs. ; We report on theoretical elastic and experimental vibrational-excitation differential cross sections (DCSs) for electron scattering from para-benzoquinone (C6H4O2), in the intermediate energy range 15–50 eV. The calculations were conducted with two different theoretical methodologies, the Schwinger multichannel method with pseudopotentials (SMCPP) and the independent atom method with screening corrected additivity rule (IAM-SCAR) that also nowincorporates a further interference (I) term. The SMCPP with N energetically open electronic states (Nopen) at the static-exchange-pluspolarisation (Nopench-SEP) level was used to calculate the scattering amplitudes using a channel coupling scheme that ranges from 1ch-SE up to the 89ch-SEP level of approximation.We found that in going from the 38ch-SEP to the 89ch-SEP, at all energies considered here, the elastic DCSs did not change significantly in terms of both their shapes and magnitudes. This is a good indication that our SMCPP 89ch-SEP elastic DCSs are converged with respect to the multichannel coupling effect for the investigated intermediate energies. While agreement between our IAM-SCAR+I and SMCPP 89ch- SEP computations improves as the incident electron energy increases from 15 eV, overall the level of accord is only marginal. This is particularly true at middle scattering angles, suggesting that our SCAR and interference corrections are failing somewhat for this molecule below50 eV.We also report experimental DCS results, using a crossed-beam apparatus, for excitation of some of the unresolved ("hybrid") vibrational quanta (bands I–III) of para-benzoquinone. Those data were derived from electron energy loss spectra that were measured over a scattered electron angular range of 10–90 and put on an absolute scale using our elastic SMCPP 89ch-SEP DCS results. The energy resolution of our measurements was s80 meV, which is why, at least in part, the observed vibrational features were only partially resolved. To the best of our knowledge, there are no other experimental or theoretical vibrational excitation results against which we might compare the present measurements. ; This study has been partially supported by the Spanish Ministry MINECO (Project No. FIS2016-80440), COST (CM301 Action) and ITN-Marie Curie (No. ARGENT-608163) European Union programmes. M.A.P.L., M.T.do.N.V. (Grant No. 305672/2014-2), R.F.C., and M.H.F.B. all acknowledge financial support from CNPq, while F.K. (Grant No. 2015/23792-5) and M.T.do.N.V. (Grant No. 2014/10012-9) also thank FAPESP for financial support. Finally, M.J.B. (No. DP160102787) and R.D.W. acknowledge the Australian Research Council for funding. ; Peer Reviewed
Abstract. This study describes and interprets the evolution of grain-size distribution of sediment yields generated in an experimental soil flume subjected to downstream and upstream moving rain storms. Results of laboratory experiments show that downstream moving storms cause more soil loss than do upstream moving storms. The pattern of sediment grain-size evolution in time during a runoff event exhibits a clear dependence on the direction of storm movement. A strong relationship between overland flow discharge and mean sediment size is found. Nevertheless, the mean grain-size of sediments transported during the rising limb of the hydrograph is coarser than during the recession limb of the hydrograph. This is more marked for downstream moving storms.
8 pags., 3 figs., 4 tabs. ; We report absolute experimental integral cross sections (ICSs) for the electron impact excitation of 6 bands (Bands 0-V) of unresolved electronic-states in para-benzoquinone, for incident electron energies between 20 and 40 eV. Absolute vibrational-excitation ICSs, for 3 composite vibrational bands (Bands I-III), are also reported in that same energy range. In addition, ICSs calculated within our independent atom model (IAM) with screening corrected additivity rule (SCAR) formalism, extended to account for interference (I) terms that arise due to the multi-centre nature of the scattering problem, are also reported. The sum of those ICSs gives the IAM-SCAR+I total cross section (TCS) for electron-para-benzoquinone scattering. Where possible, those calculated IAM-SCAR+I ICSs are compared against corresponding results from the present measurements with an acceptable level of accord being obtained. Similarly, we also present results from our Schwinger multichannel method with pseudopotential (SMCPP) calculations. Here elastic ICSs and ICSs corresponding to the Bands 0-III of unresolved electronic-states are presented, with agreement between the SMCPP electronic-state ICSs and those from our measurements being in good qualitative accord. The energy range of our SMCPP computations is 16-50 eV. Using the binary-encounter-Bethe (BEB) approach, total ionization cross sections for this collision system were computed. Those total ionization cross sections were then added to our SMCPP ICS results, to derive SMCPP/BEB TCSs that are typically in very good accord with those from our IAM-SCAR+I approach. ; This study was partially supported by the Australian Research Council (ARC) through Grant No. DP160120787. It was also partially supported by the Spanish Ministry MINECO (Project No. FIS2016-80440), the COST Action (No. CM301), and the ITN-Marie Curie (No. ARGENT-608163) European Union programme. M.A.P.L., M.T.do.N.V. (Grant I.D. No. 305672/2014-2), R.F.da.C., and M.H.F.B. all thank CNPq for financial support, while F.K. (Grant I.D. No. 2015/23792-5) also thanks FAPESP for financial support. Finally, M.H.F.B. acknowledges computational support from Professor Carlos de Carvalho at LFTC-DFis-UFPR and at LCPAD-UFPR and from CENAPAD-SP.
8 págs.; 4 figs.; 4 tabs. ; We report cross sections for electron-impact excitation of vibrational quanta in furfural, at intermediate incident electron energies (20, 30, and 40 eV). The present differential cross sections are measured over the scattered electron angular range 10°-90°, with corresponding integral cross sections subsequently being determined. Furfural is a viable plant-derived alternative to petrochemicals, being produced via low-temperature plasma treatment of biomass. Current yields, however, need to be significantly improved, possibly through modelling, with the present cross sections being an important component of such simulations. To the best of our knowledge, there are no other cross sections for vibrational excitation of furfural available in the literature, so the present data are valuable for this important molecule. C 2015 AIP Publishing LLC ; This work was supported by the Australian, Brazilian, and Spanish government funding agencies (ARC, CNPq, CAPES). D.B.J. thanks the ARC for a Discovery Early Career Researcher Award. R.F.C.N. acknowledges CNPq and Flinders University for financial asistance, while M.J.B. thanks CNPq for his "Special Visiting Professor" award. R.F.C., M.T.N.V., and M.A.P.L. acknowledge financial support from FAPESP, while R.F.C., M.T.N.V., M.H.F.B., M.C.A.L., and M.A.P.L. acknowledge financial support from CNPq. M.C.A.L. also acknowledges support from FAPEMIG. G.G. thanks the Spanish Ministerio de Economía y Competitividad under Project No. FIS2012-31230 and the European Union COST Action CM1301 for funding. ; Peer Reviewed
10 pags., 7 figs., 7 tabs. ; Angle resolved electron energy loss spectra (EELS) for para-benzoquinone (CHO) have been recorded for incident electron energies of 20, 30, and 40 eV. Measured differential cross sections (DCSs) for electronic band features, composed of a combination of energetically unresolved electronic states, are subsequently derived from those EELS. Where possible, the obtained DCSs are compared with those calculated using the Schwinger multichannel method with pseudopotentials. These calculations were performed using a minimum orbital basis single configuration interaction framework at the static exchange plus polarisation level. Here, quite reasonable agreement between the experimental cross sections and the theoretical cross sections for the summation of unresolved states was observed. ; This work was partially supported by the Australian Research Council (ARC) through Grant No. DP160120787. It was also partially supported by the Spanish Ministry MINECO (Project No. FIS2016-80440), the COST Action (CM301), and ITN-Marie Curie (ARGENT-608163) European Union programmes. M.A.P.L., M.T.d.N.V. (Grant I.D. 305672/2014- 2), R.F.d.C., and M.H.F.B. all acknowledge financial support from CNPq, while F.K.(Grant I.D. 2015/23792-5) also thank FAPESP for financial support. F.F.d.S. acknowledges the Portuguese National Funding Agency FCT-MCTES through a researcher position IF-FCT IF/00380/2014 and together with P.L.-V. the research Grant No. UID/FIS/00068/2013.
