DSpace@Cambridge: implementing long-term digital preservation

This article describes one approach towards digital preservation and long-term accessibility of content in DSpace@Cambridge anno 2005.DSpace@Cambridge is an institutional archive set up to deal with the long-term preservation of information in a wide range of formats over an indefinite period of time. In this paper we look at some long-term digital preservation strategies, as they are currently implemented in our archive. We describe the value of documentation of file format specifications for future data accessibility. We examine the impact and usefulness of constant concurrent data migration to several different formats. We illustrate our approach with case studies of applying these principles to chemical and archeological scientific data

Use of automated rendezvous trajectory planning to improve spacecraft operations efficiency

The current planning process for space shuttle rendezvous with a second Earth-orbiting vehicle is time consuming and costly. It is a labor-intensive, manual process performed pre-mission with the aid of specialized maneuver processing tools. Real-time execution of a rendezvous plan must closely follow a predicted trajectory, and targeted solutions leading up to the terminal phase are computed on the ground. Despite over 25 years of Gemini, Apollo, Skylab, and shuttle vehicle-to-vehicle rendezvous missions flown to date, rendezvous in Earth orbit still requires careful monitoring and cannot be taken for granted. For example, a significant trajectory offset was experienced during terminal phase rendezvous of the STS-32 Long Duration Exposure Facility retrieval mission. Several improvements can be introduced to the present rendezvous planning process to reduce costs, produce more fuel-efficient profiles, and increase the probability of mission success

Mean and fluctuating suspended sediment concentration measurements using ADV

The present experimental research looks for ways to improve fine sediment transport measurements with ADV by further investigating the factors influencing the backscatter intensity of the acoustic wave. The optimal instrument settings are determined in order to maximally extend the region of increasing response to fine suspended sediments in the sampling volume and a spectral correction is used to obtain turbulent sediment concentration fluctuations

Effect of bed roughness on the mixing layers in a 90° asymmetrical confluence

In this paper, the mixing layer between the two incoming flows in a 90 degree, asymmetrical open channel confluence is investigated. Specific attention is given towards looking into the effect of bed roughness on the flow patterns in the confluence. This analysis is performed in a Serret-Frenet type axis system, in order to come up with a more convenient way of representing the measurement data. The effects on the velocity distribution, velocity difference over the mixing layer, width and location of the mixing layer are studied, and found to be influenced

Influence of cross-sectional shape on flow patterns in an open-channel confluence

The state-of-the-art hydrodynamic knowledge on schematized open-channel confluences is largely based on laboratory experiments in channels with a rectangular cross-section. Since in practice man-made canals often have a nonrectangular cross-section, the question can be raised to which extent the knowledge on open-channel confluences still holds for confluences of that type of canals. Therefore, this paper examines the influence of three cross-sectional shapes on the flow patterns in an asymmetric 90° open-channel confluence with fixed concordant bed and subcritical flows throughout. Large-eddy simulations are performed for a rectangular, a chamfered rectangular and a trapezoidal section. The simulations for the non-rectangular sections show that the location of both the mixing layer between the incoming flows and the shear layer between the separation zone and the contracted section are altered in comparison to the rectangular section case. Also the evolution of the separation zone is found to be different. It is demonstrated that the distribution of incoming momentum and the shape of the confluence corners are primary causes of the observed deviations

Immune cells in chronic lymphocytic leukemia and Hodgkin lymphoma in relation to tumor burden and treatment

B-cell malignancies are a heterogeneous group of cancers that originate from lymphoidlineage cells that are responsible for humoral immunity. When B-cell development goes wrong, chronic lymphocytic leukemia (CLL) and classical Hodgkin lymphoma (cHL), among other malignancies, may arise. Recent advances in the treatment of these diseases, e.g., ibrutinib in CLL, have greatly improved the prognosis of patients, but also introduced new challenges. Gaining knowledge about the effects that these treatments have on immune cells might help us overcome these challenges. In Paper I, we described our efforts to further elucidate the on- and off-target mechanisms behind ibrutinib’s common adverse events and immune effects by performing proximity extension assays to measure 265 plasma biomarkers and flow cytometry to assess the immune cell dynamics throughout 5 years of ibrutinib treatment in 13 CLL patients. In Paper II, we tested the safety and feasibility of a novel intermittent dosing strategy for ibrutinib. Treatment was interrupted in CLL patients who were in remission and resumed when early sign of progression occurred in a repetitive fashion. In paper III, we characterized the influences that cHL has on circulating lymphocytes in relation to clinical parameters and first-line treatment. We found that numerous biomarkers changed during ibrutinib treatment and categorized them by cellular origin and related conditions. Interestingly, we discovered 6 potential mediators of ibrutinib-induced atrial fibrillation. We also showed that successful ibrutinib treatment leads to a reduction in all T-cell populations, including T helper 1 cells, Tregs and exhausted T cells, which paralleled the declining tumor burden. T helper 2 (Th2) cells remained relatively stable, causing Th2-skewing. Interrupting ibrutinib turned out to be safe in CLL patients that are in a sustained remission and resuming the drug upon early signs of progression induced new objective responses. Circulating T cells in cHL were found to be exhausted and terminally differentiated, B- and natural killer-cell numbers were low, and inflammation and tumor burden were related to distinct immune profiles. Standard first-line treatment reversed most changes. However, radiotherapy involving the mediastinum seemed to selectively reduce T cells. We conclude from these studies that ibrutinib has broad immunomodulatory effects and that several investigated biomarkers might be involved in ibrutinib-induced atrial fibrillation. Moreover, ibrutinib can safely be interrupted in responding CLL patients, who remain drugsensitive when progressive disease occurs. The risk of serious infections seems to be lower when patients are off the drug. On top of the well-studied control that malignant cells have over the immune cells in the tumor microenvironment, cHL patients have signs of systemic immunosuppression as well, which could be solved to a large extent by standard front-line treatment

Influence of hydraulic resistance on flow features in an open channel confluence

A numerical model based on the 3D shallow water equations is set up for a 90° angle open channel confluence. The model is first calibrated and validated using experimental data by (Shumate, 1998). Then a series of numerical simulations is carried out, systematically increasing the friction coefficient, in order to investigate the impact of hydraulic resistance on the flow features in an open channel confluence. The properties of the separation zone (width and length) are found to be substantially altered by the hydraulic resistance. The hydrodynamic processes are analysed zooming in onto lateral momentum fluxes

Experimental investigation of negatively buoyant sediment plumes resulting from Dredging operations

In a first step to investigate the behaviour of sediment plumes released from dredging vessels, an experimental facility has been built to release scaled fine sediment plumes in the presence of cross flow. High-frequency measurements of velocity components and sediment concentration are obtained using acoustic and optical backscatter instruments. The paths of the axis of the experimental buoyant plumes in cross-flow have been compared to integral laws by Fisher et al. (1979), showing relatively good agreement for plumes not influenced by the dredger’s hull. Plumes with low relative density difference and high crossflow to outflow velocity ratio deviate from the integral laws due to additional mixing induced by the hull boundary layer and wake

Influence of bed elevation discordance on flow patterns and head losses in an open-channel confluence

Confluences play a major role in the dynamics of networks of natural and man-made open channels, and field measurements on river confluences reveal that discordance in bed elevation is common. Studies of schematized confluences with a step at the interface between the tributary and the main channel bed reveal that bed elevation discordance is an important additional control for the confluence hydrodynamics. This study aimed to improve understanding of the influence of bed elevation discordance on the flow patterns and head losses in a right-angled confluence of an open channel with rectangular cross-sections. A large eddy simulation (LES)-based numerical model was set up and validated with experiments by others. Four configurations with different bed discordance ratios were investigated. The results confirm that, with increasing bed elevation discordance, the tributary streamlines at the confluence interface deviate less from the geometrical confluence angle, the extent of the recirculation zone (RZ) gets smaller, the ratio of the water depth upstream to that downstream of the confluence decreases, and the water level depression reduces. The bed elevation discordance also leads to the development of a large-scale structure in the lee of the step. Despite the appearance of the large-scale structure, the reduced extent of the RZ and associated changes in flow deflection/contraction reduce total head losses experienced by the main channel with an increase of the bed discordance ratio. It turns out that bed elevation discordance converts the lateral momentum from the tributary to streamwise momentum in the main channel more efficiently. (C) 2019 Hohai University. Production and hosting by Elsevier B.V