Diffusion of bedload particles in open-channel flows : distribution of travel times and second-order statistics of particle trajectories

Acknowledgments The authors are grateful to the reviewers for thorough reviews, constructive comments and useful suggestions that have been gratefully incorporated in the final manuscript. Funding for this research was provided in part by the Institute of Geophysics of the Polish Academy of Sciences through the Project for Young Scientists No. 16/IGF PAN/2011/Mł ‘‘Dynamics and topography of riverbed forms: an analysis of experimental data and modelling of sediment transport in the light of Einstein’s theory’’, by Ministry of Sciences and Higher Education within statutory activities No. 3841/E-41/S/2015, and by EPSRC, UK (EP/G056404/1) within the project ‘‘High-resolution numerical and experimental studies of turbulence-induced sediment erosion and near-bed transport.’’ Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.Peer reviewedPublisher PD

Climatic conditions at Arctowski Station (King George Island, West Antarctica) in 2013–2017 against the background of regional changes

This paper provides an overview of the results of research on changes in ground temperature down to 50 cm depth, on the Kaffiøyra Plain, Spitsbergen in the summer seasons. To achieve this, measurement data were analysed from three different ecotopes (CALM Site P2A, P2B and P2C) – a beach, a moraine and tundra – collected during 22 polar expeditions between 1975 and 2014. To ensure comparability, data sets for the common period from 21 July to 31 August (referred to as the “summer season” further in the text) were analysed. The greatest influence on temperature across the inves− tigated ground layers comes from air temperature (correlation coefficients ranging from 0.61 to 0.84). For the purpose of the analysis of the changes in ground temperature in the years 1975–2014, missin

Bedload transport in two creeks at the ice-free area of the Baranowski Glacier, King George Island, West Antarctica

This paper presents a unique case study and methodology for measurements of the bedload transport in the two, newly created troughs at the forefield of the Baranowski Glacier: Fosa and Siodło creeks. The weather conditions and the granulometric analysis are presented and discussed briefly. Rating curves for the Fosa and Siodło creeks are presented for the first time for this region. Changes of the bedload transport as well as water discharge and water velocity at both creeks are investigated. The hysteresis for the relationships between rate of bedload transport and water discharges were identified showing that for both creeks for the higher water levels a figure of eight loop may be easily recognized. Moreover, a new method for the calculation of bedload transport rate, based on the weighted arithmetic mean instead of the arithmetic mean, is proposed

Dissolved oxygen and water temperature dynamics in lowland rivers over various timescales

The impact of floodplain hydrology on the in-stream dissolved oxygen dynamics and the relation between dissolved oxygen and water temperature are investigated. This has been done by examining the time series of dissolved oxygen and water temperature coupled with meteorological and hydrological data obtained from two lowland rivers having contrasting hydrological settings. Spectral analysis of long-term oxygen variations in a vegetated river revealed a distinct scaling regime with slope ‘–1’ indicating a self-similar behaviour. Identical slopes were obtained for water temperature and water level. The same power-law behaviour was observed for an unvegetated river at small timescales revealing the underlying scaling behaviour of dissolved oxygen regime for different types of rivers and over various time scales. The results have shown that the oxygenation of a vegetated river is strongly related to its thermal regime and flow conditions. Moreover, analysis of short-term fluctuations in the unvegetated river demonstrated that physical factors such as rainfall and backwaters play a substantial role in the functioning of this ecosystem. Finally, the results show that the relation between water temperature and dissolved oxygen concentration at the diurnal timescale exhibits a looping behaviour on the variable plot. The findings of this study provide an insight into the sensitivity of rivers to changing hydro-physical conditions and can be useful in the assessment of environmental variability

Treatment of primary dysthymia with group cognitive therapy and pharmacotherapy: clinical symptoms and functional impairments

Objective: This study assessed the efficacy of antidepressant treatment (sertraline) and group cognitive behavior therapy, alone or in combination, in primary dysthymia. The clinical features of dysthymia, as well as the functional impairments associated with the illness (e.g., quality of life, stress perception, coping styles), were evaluated. Method: Patients (N = 97) diagnosed with primary dysthymia, but no other current comorbid disorder, received either sertraline or placebo in a double-blind design over 12 weeks. In addition, a subgroup of the patients (N = 49) received a structured, weekly group cognitive behavior therapy intervention. Results: Treatment with sertraline, with or without group cognitive behavior therapy, reduced the functional impairment of depression. The reductions were similar in the drug-cognitive therapy group and in subjects who received the drug alone. Furthermore, while group cognitive behavior therapy alone reduced the depression scores, this effect was not significantly greater than the effect of the placebo. The drug treatment also induced pronounced improvement in the functional measures, and in some respects these effects were augmented by group cognitive behavior therapy. Among patients who responded favorably to cognitive behavior therapy, the improvements in the functional measures were similar to those who responded to drug treatment, whereas such functional changes were not seen among patients who responded to placebo. Conclusions: Sertraline treatment effectively reduces the clinical symptoms and functional impairments associated with dysthymia. Although the group cognitive behavior therapy intervention was less effective in alleviating clinical symptoms, it augmented the effects of sertraline with respect to some functional changes, and in a subgroup of patients it attenuated the functional impairments characteristic of dysthymia

An analysis of entrainment and deposition rate fluctuations in weak bed load transport

The kinematics of particles moving over a fixed rough bed was experimentally investigated. Motion of sediment particles was recorded from the top of a pressurized duct using a CCD camera, and the then image processing was applied in order to track each particle. Particle tracking provides quantitative information about the time evolution of particle position and velocity. However, in this paper, the attention is focused onto the entrainment and deposition of particles. The entrainment rate may be used to quantify the solid discharge (through, for example, some pick-up function); the deposition rate is the counterpart of the former, that has however received comparatively less attention in previous studies of sediment transport. Temporal signals of the entrainment and deposition rates were investigated for different spatial and temporal scales, demonstrating how the intermittency of the transport process affects the fluctuation patterns. Consequently, the (spatial or temporal) scale dependency of the statistical moments of these rates was explored. An expected result was found, with scale-independent average values of the entrainment and deposition rates and a strong dependence on the support scale for the standard deviation values

The artist as nation-builder: William Butler Yeats and Chaim Nachman Bialik

The poets William Butler Yeats (1865–1939) and Chaim Nachman Bialik (1873–1934) were among the builders of their respective Irish and Jewish national cultures. Their lives and careers were in limited ways remarkably alike and throw light on the dynamics of cultural nationalism. Each emerged in an historical watershed, leading to the establishment of an Irish state in 1921 and a Jewish state in 1948. Though their circumstances, styles, receptions and fates differed, each represented a profound moral vision in an age of declining faith, expressed his people's sense of victimisation and exposed their weaknesses as he saw them. Each saw his culture as being humanist and universal, not narrowly nationalistic. Each identified with his nation for reasons that were in part intensely and disturbingly personal. Each found a poetic voice in a rich heritage of ethnic myth, legend and symbol but was conscious of tension between the need for self-expression and national demands. It is argued that the creative powers of both Yeats and Bialik were set free by the national movements of which they were a part, and that the national struggle for self-determination was, in effect, mirrored on the private scale by the poet striving for artistic freedom and originality