Spinning jets

A fluid jet with a finite angular velocity is subject to centripetal forces in addition to surface tension forces. At fixed angular momentum, centripetal forces become large when the radius of the jet goes to zero. We study the possible importance of this observation for the pinching of a jet within a slender jet model. A linear stability analysis shows the model to break down at low viscosities. Numerical simulations indicate that angular momentum is expelled from the pinch region so fast that it becomes asymptotically irrelevant in the limit of the neck radius going to zero

New bryophyte taxon records for tropical countries 4

Nord Kivu: c. 6 km north of Lubero, on sandy soil of tree-shaded road cutting, c. 1800m, 0º 8' S, 29º 14' E, 11 Aug 1988. C.R. Stevenson Z 78f, det. E.W. Jones (BM, & herb. C.R. Stevenson). Growing mixed with Frullania serrata, Pilotrichella, Trachypodopsis, etc. Distrib.: Annobon, Bioko, Burundi, Cameroun, Kenya, Rwanda, Sao Tome, Tanzania

Chapter 24 Freedom and Form in Piano Improvisation in the Early 19th Century

The idea of improvisation, broadly defined, has been integral to our imagination of the medieval musical past. It can be related to many elements of production: to the act of un-notated creation; to the manipulation and amplification of notated materials; to our observance of rigid rules and formulae; or to spontaneous freedom. Likely a product of the Carolingian Renaissance, this is the first medieval music treatise to address an aspect of chant performance that does not only relate to a memorized repertoire, but includes an unwritten practice of extemporizing an accompanying voice to a pre-given melody. The art of “coloration” or the ornamentation of a line, whether polyphonic or monophonic, had been an integral part of extemporization since at least the time of the Ad organum faciendum treatises. When planning author's ontological inquiries, the author's would do well to remember the possible existence of creativity that is not inspired, or ephemerality that is not performer- or expression-centered

Chapter 24 Freedom and Form in Piano Improvisation in the Early 19th Century

The idea of improvisation, broadly defined, has been integral to our imagination of the medieval musical past. It can be related to many elements of production: to the act of un-notated creation; to the manipulation and amplification of notated materials; to our observance of rigid rules and formulae; or to spontaneous freedom. Likely a product of the Carolingian Renaissance, this is the first medieval music treatise to address an aspect of chant performance that does not only relate to a memorized repertoire, but includes an unwritten practice of extemporizing an accompanying voice to a pre-given melody. The art of “coloration” or the ornamentation of a line, whether polyphonic or monophonic, had been an integral part of extemporization since at least the time of the Ad organum faciendum treatises. When planning author's ontological inquiries, the author's would do well to remember the possible existence of creativity that is not inspired, or ephemerality that is not performer- or expression-centered

Benchmarking and environmental performance classes in life cycle assessment—development of a procedure for non-leather shoes in the context of the Product Environmental Footprint

Purpose: In the process of developing Product Environmental Footprint Category Rules (PEFCR)—currently tested in various pilots in the Single Market for Green Products initiative of the European Commission—the definition of product category benchmarks and environmental performance classes is a crucial element of each PEFCR. Whilst life cycle assessment (LCA) methodology developed over the last 20 years can be used for many other topics to be tackled in the pilots, there is a clear lack of methodology for the determination of benchmarks and environmental performance classes. In this article, hence, we address this gap and develop a procedure for benchmarking and environmental performance classes in LCA. Methods: To do this, given requirements and definitions of the PEF guidelines on both subjects are taken as a basis and are refined by using common LCA techniques like hot spot and sensitivity analyses. The specific steps of the procedure are applied systematically in a case study using sports shoes as an example. Results and discussion: The resulting procedure involves the definition of a scenario vector, which is composed of relevant life cycle phases as well as the lifetime of the product (i.e. sports shoes) as variables. On the basis of the hot spot and sensitivity analyses, these variables are quantified, first, to generate the benchmark and, second, to determine the environmental performance classes around the benchmark for each considered impact category individually. In addition, the influence of data uncertainty on the class distribution is assessed with the help of the Monte Carlo simulation. Conclusions: The results of the application in the case study demonstrate the high impact of the product’s lifetime on the final environmental performance classes, and the importance of data quality. Limitations are identified regarding data availability and the harmonisation of the classes to potentially create a PEF label. A debate is induced on the validity of such a label when considering the fact that the characterisation methods and factors proposed in the PEF guidelines may not be complete or accurate enough

The Two Fluid Drop Snap-off Problem: Experiments and Theory

We address the dynamics of a drop with viscosity $\lambda \eta$ breaking up inside another fluid of viscosity $\eta$. For $\lambda=1$, a scaling theory predicts the time evolution of the drop shape near the point of snap-off which is in excellent agreement with experiment and previous simulations of Lister and Stone. We also investigate the $\lambda$ dependence of the shape and breaking rate.Comment: 4 pages, 3 figure