Investigation into the Strouhal numbers associated with vortex shedding from parallel-plate thermoacoustic stacks in oscillatory flow conditions

This paper investigates vortex shedding processes occurring at the end of a stack of parallel plates, due to an oscillating flow induced by an acoustic standing wave. Here the hot-wire anemometry measurement technique is applied to detect the velocity fluctuations due to vortex shedding near the end of the stack. The hot-wire fast time response enables obtaining detailed frequency spectra of the velocity signal, which can be used for identifying the dominant frequencies associated with vortex shedding, and thus allow calculating the corresponding Strouhal numbers. By varying the stack configuration (the plate thickness and spacing) and the acoustic excitation level (the so-called drive ratio), the impact ofthe stack blockage ratio and the Reynolds number on the Strouhal number has been studied in detail. Furthermore, in the range of the Reynolds numbers between 200 and 5,000 a correlation between the Strouhal number and Reynolds number has been obtained and compared with analogous relationships in the steady flow. Particle Image Velocimetry (PIV) is also used to visualize the vortex shedding processes within an acoustic cycle, phase-by-phase, in particular during the part of the cycle when the fluid flows out of the stack – selected cases are shown for comparisons with hotwire measurements

Selection and experimental evaluation of low-cost porous materials for regenerator applications in thermoacoustic engines

This paper aims at evaluating three selected low-cost porous materials from the point of view of their suitability as regenerator materials in the design of thermoacoustic travelling wave engines. The materials tested include: a cellular ceramic substrate with regular square channels; steel “scourers”; and stainless steel “wool”. Comparisons are made against a widely used regenerator material: stainless steel woven wire mesh screen. For meaningful comparisons, the materials are selected to have similar hydraulic radii. One set of regenerators was designed around the hydraulic radius of 200 μm. This included the ceramic substrate, steel “scourers”, stainless steel “wool” and stacked wire screens (as a reference). This set was complemented by steel “scourers” and stacked wire screens (as a reference) with hydraulic radii of 120 μm. Therefore six regenerators were produced to carry out the testing. Initial tests were made in a steady air flow to estimate their relative pressure drop due to viscous dissipation. Subsequently, they were installed in a looped-tube travelling-wave thermoacoustic engine to test their relative performance. Testing included the onset temperature difference, the maximum pressure amplitude generated and the acoustic power output as a function of mean pressure between 0 and 10 bar above atmospheric. It appears that the performance of regenerators made out of “scourers” and steel “wool” is much worse than their mesh-screen counterparts of the same hydraulic radius. However cellular ceramics may offer an alternative to traditional regenerator materials to reduce the overall system costs. Detailed discussions are provided

Current insights into matrix metalloproteinases and glioma progression: transcending the degradation boundary

Abstract: Glioblastoma multiforme (GBM) remains one of the most deadly cancers, with modest advances in overall survival despite significant improvements in imaging, surgery, and molecular genomic understanding. The highest-grade glioma, GBM is a primary brain cancer that is molecularly heterogeneous among patients and even within the same patient. Key hallmarks include glioma-cell invasion, angiogenesis, and therapeutic resistance. While once considered a major player in glioma invasion, members of the MMP family are also associated with other key pathological hallmarks of glioma. Investigations into understanding MMP function in GBM were slowed due to the failed MMP-inhibitor trials for GBM in the 2000s. In contrast, the field of MMPs in other brain pathologies has flourished in such areas as traumatic brain injury, multiple sclerosis, and stroke. In the past decade, the increase in publicly available data sets documenting patient-biopsy molecular information has empowered laboratory investigations into the spectrum of genomic, transcriptomic, and proteomic changes associated with glioma, including MMPs. In this review, we selected one of these data sets to illustrate a small sample of information that can be obtained from such analyses. Combined with recent reports on the use of MMP-cleavable peptides for imaging and the multifunctionality of MMPs, including intracellular nonproteolytic actions in various cell types, this paves the way for new avenues of MMP research. Understanding the function of MMPs in host–tumor interactions both spatially and temporally during tumor progression and in response to treatment will be crucial for the advancement of targeting specific MMPs in GBM. The opportunities to explore MMP regulation, expression, and function further in GBM have never been so great with progress in modern bioinformatics and molecular techniques, and it is hoped that advancements will translate in some way to patients diagnosed with GBM

Drucker\u27s Insights on Market Orientation and Innovation: Implications for Emerging Areas in High-Technology Marketing

In 1954, Drucker boldly declared that organizations have only two basic functions, marketing and innovation. While true for any organization, this insight is particularly pertinent for technology-based businesses. The complicated environment surrounding high-tech companies creates a great need for sophisticated marketing, yet these companies continue to have under-developed competencies in marketing and in understanding customer needs. In its first two sections, this essay explores Drucker’s insights with respect to two particularly salient issues for high-tech companies: developing and implementing a market orientation, and sustained break-through innovations. We review Drucker’s insights and synthesize them with the scholarly research on these issues. In the third section, we discuss three emerging areas in high-tech marketing where academics and managers could build on Drucker’s insight to guide future research and practice: market-driving, customer co-creation, and corporate social responsibility. The illustrative examples provided by these emerging areas highlight that even today, Drucker’s writings continue to offer remarkable guidance to scholars and managers who are willing to take the time to reflect, understand, and incorporate these insights in the unique context of high-tech industries

Culture and collective action: Japan, Germany and the United States after 11 September 2001

In order to put a lens on the issue of international security cooperation after 11 September 2001, this article examines the question of how collective action in International Relations becomes possible. The author maintains that a fair amount of inter-state collective action can be understood, even explained, by analysing the culture of the international system. Using discourse analysis as a tool, the analysis addresses the underlying ideas, norms and identities that constitute the relationship between the United States and Japan, on the one hand, and Germany and the United States, on the other, as it has evolved since September 2001. The method exposes how some ideas are privileged over others, how norms are maintained, reformulated and abandoned, how identity is constructed and how power is legitimized in the 'war on terror'

Management control systems in innovation companies: A literature based framework

Past research has traditionally argued that management control systems (MCSs) may present a hindrance to the creativity of innovation companies. This theoretical paper surveys the literature to focus an investigation on the MCSs of innovation companies. Within the object of control paradigm the paper develops and presents a theoretical model of the impact of eleven external, organisational and innovation related contingency factors on the MCSs in companies that engage in innovation activities. We also suggest measures for further empirical research. By formulating hypotheses on 43 potential interactions the model predicts contradictory influences on two direct control categories, results and action control, but stresses the importance of two indirect categories, personnel and cultural control. More specifically, the high levels of technological complexity and innovation capability in this type of company are expected to be negatively associated with the application of results and action control, whereas personnel and cultural seem to be more appropriate. Furthermore, important sources of finance, venture capital and public funding, are both hypothesised to be positively associated with the application of results, action and personnel control; whereas only public funding is predicted to be positively related to the application of cultural control. The principal contribution of this paper lies in synthesising the literature to provide a model of the impact of a unique set of eleven contingency factors for innovation companies on a broad scope of controls. In addition, the contingency model, if empirically validated, would add value by inferring the particular forms of management control which would be beneficial in innovative company settings. © 2014 Springer-Verlag Berlin Heidelberg

Integrated pest management of Tuta absoluta: practical implementations across different world regions

The South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), has invaded most Afro-Eurasian countries and is threatening worldwide tomato production. Various strategies have been developed and implemented to manage this pest. Here, we present a timely review on the up-to-date development and practical implementation of integrated pest management (IPM) programs for tomato crops across different world regions infested by T. absoluta. While insecticide resistance is a growing concern, biological control via releasing or conserving arthropod natural enemies and sex pheromone-based biotechnical control are the most successful management practices. Agronomic control-related research is an emerging area where the soil fertilization and/or irrigation, as well as breeding of resistant cultivars, has the potential to enhance IPM effectiveness. Grower survey responses in the native areas (i.e., South America), early-invaded areas (i.e., first report between 2006 and 2012) and newly invaded areas (i.e., first report after 2012) showed that the control programs evolved along with the areas and time since invasion. Growers in the early-invaded areas shifted more rapidly from chemical control to biological control compared to those from the native area. In all concerned regions, the pest control failure risk following chemical insecticide applications and the high cost associated with either biological or biotechnical control methods have been the greatest concerns for growers. The information gathered from the native and/or early-invaded areas may help achieve a more effective management in newly invaded areas. Lastly, researchers are expected to break the bottlenecks of some key issues that would enable lowering application cost of novel biorational alternative management options

Watershed ‘chemical cocktails’: forming novel elemental combinations in Anthropocene fresh waters

Este artículo contiene 25 páginas, 9 figuras.In the Anthropocene, watershed chemical transport is increasingly dominated by novel combinations of elements, which are hydrologically linked together as ‘chemical cocktails.’ Chemical cocktails are novel because human activities greatly enhance elemental concentrations and their probability for biogeochemical interactions and shared transport along hydrologic flowpaths. A new chemical cocktail approach advances our ability to: trace contaminant mixtures in watersheds, develop chemical proxies with high-resolution sensor data, and manage multiple water quality problems. We explore the following questions: (1) Can we classify elemental transport in watersheds as chemical cocktails using a new approach? (2) What is the role of climate and land use in enhancing the formation and transport of chemical cocktails in watersheds? To address these questions, we first analyze trends in concentrations of carbon, nutrients, metals, and salts in fresh waters over 100 years. Next, we explore how climate and land use enhance the probability of formation of chemical cocktails of carbon, nutrients, metals, and salts. Ultimately, we classify transport of chemical cocktails based on solubility, mobility, reactivity, and dominant phases: (1) sieved chemical cocktails (e.g., particulate forms of nutrients, metals and organic matter); (2) filtered chemical cocktails (e.g., dissolved organic matter and associated metal complexes); (3) chromatographic chemical cocktails (e.g., ions eluted from soil exchange sites); and (4) reactive chemical cocktails (e.g., limiting nutrients and redox sensitive elements). Typically, contaminants are regulated and managed one element at a time, even though combinations of elements interact to influence many water quality problems such as toxicity to life, eutrophication, infrastructure corrosion, and water treatment. A chemical cocktail approach significantly expands evaluations of water quality signatures and impacts beyond single elements to mixtures. High-frequency sensor data (pH, specific conductance, turbidity, etc.) can serve as proxies for chemical cocktails and improve real-time analyses of water quality violations, identify regulatory needs, and track water quality recovery following storms and extreme climate events. Ultimately, a watershed chemical cocktail approach is necessary for effectively co-managing groups of contaminants and provides a more holistic approach for studying, monitoring, and managing water quality in the Anthropocene.This work was funded by USDA (award # 2016-67019-25280) and NSF-EPSCoR (#1641157) for supporting collaborations at the AGU Chapman Conference on Extreme Climate Events. Significant funding for data collection/analyses in this paper was provided by NSF EAR1521224, NSF CBET1058502, NSF Coastal SEES1426844, NSF DEB-0423476 and DEB-1027188, NSF RI EPSCoR NEWRnet Grant No. IIA-1330406, EPA ORD, Chesapeake Bay Trust, and Multi-state Regional Hatch Project S-1063.Peer reviewe