Transport of ferrihydrite nanoparticles in saturated porous media: role of ionic strength and flow rate

The use of nanoscale ferrihydrite particles, which are known to effectively enhance microbial degradation of a wide range of contaminants, represents a promising technology for in situ remediation of contaminated aquifers. Thanks to their small size, ferrihydrite nanoparticles can be dispersed in water and directly injected into the subsurface to create reactive zones where contaminant biodegradation is promoted. Field applications would require a detailed knowledge of ferrihydrite transport mechanisms in the subsurface, but such studies are lacking in the literature. The present study is intended to fill this gap, focusing in particular on the influence of flow rate and ionic strength on particle mobility. Column tests were performed under constant or transient ionic strength, including injection of ferrihydrite colloidal dispersions, followed by flushing with particle-free electrolyte solutions. Particle mobility was greatly affected by the salt concentration, and particle retention was almost irreversible under typical salt content in groundwater. Experimental results indicate that, for usual ionic strength in European aquifers (2 to 5 mM), under natural flow condition ferrihydrite nanoparticles are likely to be transported for 5 to 30 m. For higher ionic strength, corresponding to contaminated aquifers, (e.g., 10 mM) the travel distance decreases to few meters. A simple relationship is proposed for the estimation of travel distance with changing flow rate and ionic strength. For future applications to aquifer remediation, ionic strength and injection rate can be used as tuning parameters to control ferrihydrite mobility in the subsurface and therefore the radius of influence during field injection

Flexible Unterstützung kooperativer Entwurfsumgebungen durch einen Transaktions-Baukasten

Entwurfsumgebungen stellen besondere Anforderungen an das Transaktionsmanagement, so z.B. bei der Realisierung von Kooperations- und Recoverymechanismen. Hierbei ergibt sich ein Zielkonflikt: Einerseits soll das System größtmögliche Sicherheit garantieren, andererseits sollen Flexibilität und Freiheit der Entwickler nicht eingeschränkt werden. Dieser Konflikt kann durch konfigurierbare Systeme gelöst werden, die die Definition unterschiedlicher Typen von Transaktionen und damit die Anpassung an die Anforderungen der jeweiligen Umgebung erlauben. In diesem Papier werden auf der Basis eines Baukasten-Konzeptes Mechanismen zur Unterstützung von Kooperation und Recovery für Entwurfstransaktionen vorgestellt. Der zentrale Gedanke ist, daß Transaktionen bestimmte Rechte erwerben können und die Vergabe dieser Rechte durch Protokolle kontrolliert wird

Towards Bridging the Gap Between BDA Challenges and BDA Capability: A Conceptual Synthesis Based on a Systematic Literature Review

Big data analytics (BDA) and strategies for implementing BDA have received attention among researchers and practitioners alike. However, success stories pertaining to the implementation of BDA remain scarce. The notion of the BDA deployment gap describes the chasm between the attributed value potential of BDA and its actual value realization in organizational practice. Several research articles indicate challenges encountered in implementing BDA but lack a comprehensive systematization of BDA implementation-related challenges. This research article aims to systematize those challenges through a systematic literature review. As a result, we derived five overarching challenge dimensions related to the BDA implementation. Based on this systematization, we adopt the lens of a big data analytics capability and delineate future research avenues through the derivation of propositions on how to overcome the BDA implementation-related challenges, while enhancing our understanding about how to solve the BDA deployment gap

Controlling cooperation and recovery in nested transactions

Recovery is a hard problem in environments where transactions perform work in a cooperative style (e.g., design environments). We propose concepts to control cooperation and recovery within nested transaction hierarchies. By allowing different nodes to run different protocols, we can build so-called recovery spheres with well-defined properties. We characterize those properties and illustrate them by examples from design environments.<br/

How Do Individual Social Agile Practices Influence the Development Success? An Exploratory Study

Although agile software development (ASD) is widespread, thecontributions of individual agile practices to development success are still largelyunclear. In this paper, we explore the hidden cause-effect relationships betweenthe application of social agile practices, the realization of social agile principles,and the resulting contribution(s) to ASD success. To capture ASD success, weconsider both the effects on developer acceptance and economic business values.Based on an initial ASD success model and data from a survey of 197 developers,we found that social agile practices such as reflection, business IT alignment, andself-organization seem to particularly promote ASD success. We also foundindications that the realization of these principles is primarily driven by practicessuch as retrospective meetings and shared leadership, whereas prominentpractices like daily meetings and pair programming seem to have no effect. Ourresults thus call for reassessment of agile practices and their use in practice

Transparency of information disclosure in banks’ financial repors

Research topicality. The annual report, including the annual financial statements, is a key for any commercial bank to meet its accountability obligations. These statements reveal the results of the bank’s activities on its balance sheet as well as the use of resources at its disposal

The business value of agile software development: Results from a systematic literature review

A key promise of agile software development (ASD) is to deliver business value. While research and practice indeed report multiple benefits resulting from the adoption of ASD methodologies, the bandwidth of the achievable business values is not well understood yet. To clarify the concept of ASD business value and provide a systematic perspective on its multidimensional nature, we present the results of a literature review, in which we investigated the attainable benefits when adopting ASD methodologies. The contribution of the paper is twofold. First, we provide a systematic overview of 43 distinct ASD business values, which includes prominent values such as increased productivity and less regarded values, for example improved business IT alignment. Using a conceptual lens based on Chow and Cao (2008), we furthermore relate the identified business values to the factors determining the success of ASD projects, thus proposing a novel model to explain ASD success

Delineating the Business Value of Data-driven Initiatives in Organizations – Findings from a Systematic Review of the Information Systems Literature

A key objective of data-driven transformations is to utilize big data analytics (BDA) to create data-driven business value (DDBV). While prior research shows the potential of BDA to achieve DDBV, the concept remains blurry and an overview of realizable DDBVs is still lacking. To better understand the multidimensionality of the DDBV concept and to obtain insights into the bandwidth of achievable DDBVs, we conducted a systematic review of the information systems literature. Based on our results, we present a comprehensive overview of 34 DDBVs, which are classified according to their tangibility and locus of value realization. Furthermore, we describe three research deficiencies: (1) the missing operationalization of the DDBV concept, (2) the lack of explanatory mechanisms for DDBV realization, and (3) missing qualitative, in-depth insights into DDBV realization processes. Future research may build upon our systematization and help closing these research gaps, thereby increasing the success likelihood of data-driven initiatives

Direct visualization of dynamic magnetic coupling in a Co/Py bilayer with picosecond and nanometer resolution

We present a combination of ferromagnetic resonance (FMR) with spatially and time-resolved X-ray absorption spectroscopy in a scanning transmission X-ray microscope (STXM-FMR). The transverse high frequency component of the resonantly excited magnetization is measured with element-specifity in a Permalloy (Py) disk - Cobalt (Co) stripe bilayer microstructure. STXM-FMR mappings are snapshots of the local magnetization-precession with nm spatial resolution and ps temporal resolution. We directly observe the transfer of angular momentum from Py to Co and vice versa at their respective element-specific resonances. A third resonance could be observed in our experiments, which is identified as a coupled resonance of Py and Co.Comment: Version submitted to Physical Review Applied with updated author list and supplemental information (Ancillary file