Isometric Immersions and the Waving of Flags

In this article we propose a novel geometric model to study the motion of a physical flag. In our approach a flag is viewed as an isometric immersion from the square with values into $\mathbb R^3$ satisfying certain boundary conditions at the flag pole. Under additional regularity constraints we show that the space of all such flags carries the structure of an infinite dimensional manifold and can be viewed as a submanifold of the space of all immersions. The submanifold result is then used to derive the equations of motion, after equipping the space of isometric immersions with its natural kinetic energy. This approach can be viewed in a similar spirit as Arnold's geometric picture for the motion of an incompressible fluid.Comment: 25 pages, 1 figur

Electricity-assisted production of caproic acid from grass

Background: Medium chain carboxylic acids, such as caproic acid, are conventionally produced from food materials. Caproic acid can be produced through fermentation by the reverse beta-oxidation of lactic acid, generated from low value lignocellulosic biomass. In situ extraction of caproic acid can be achieved by membrane electrolysis coupled to the fermentation process, allowing recovery by phase separation. Results: Grass was fermented to lactic acid in a leach-bed-type reactor, which was then further converted to caproic acid in a secondary fermenter. The lactic acid concentration was 9.36 +/- 0.95 g L-1 over a 33-day semi-continuous operation, and converted to caproic acid at pH 5.5-6.2, with a concentration of 4.09 +/- 0.54 g L-1 during stable production. The caproic acid product stream was extracted in its anionic form, concentrated and converted to caproic acid by membrane electrolysis, resulting in a >70 wt% purity solution. In a parallel test exploring the upper limits of production rate through cell retention, we achieved the highest reported caproic acid production rate to date from a lignocellulosic biomass (grass, via a coupled process), at 0.99 +/- 0.02 g(-)L(-1) h(-1). The fermenting microbiome (mainly consisting of Clostridium IV and Lactobacillus) was capable of producing a maximum caproic acid concentration of 10.92 +/- 0.62 g L-1 at pH 5.5, at the border of maximum solubility of protonated caproic acid. Conclusions: Grass can be utilized as a substrate to produce caproic acid. The biological intermediary steps were enhanced by separating the steps to focus on the lactic acid intermediary. Notably, the pipeline was almost completely powered through electrical inputs, and thus could potentially be driven from sustainable energy without need for chemical input

Assisted reverse electrodialysis : a novel technique to decrease reverse osmosis energy demand

Assisted reverse electrodialysis (ARED) was introduced as a pre-desalination technique for seawater reverse osmosis (RO) for drinking water production. ARED is comparable to an additional applied pressure along the osmotic pressure in pressure assisted osmosis; a small voltage is applied in the same direction as the open cell voltage to increase the desalination speed compared to reverse electrodialysis (RED). This decreases the required membrane area. The concentration of the dilute compartment increases significantly during ARED operation due to the increased speed of desalination. This results in an overall decrease in total cell resistance. Although the energy demand for ARED is higher than for RED, the ARED-RO process still achieves a decrease in overall energy requirements at higher RO recoveries when compared to stand-alone RO. However, ion-exchange membrane prices will have to come down to 1-10 €/m² for the ARED-RO hybrid to become economically viable at current energy prices

Defining the Legal and Policy Framework to Stop the Dumping of Environmentally Harmful Products

Environmental dumping is a practice historically associated with the export of hazardous product waste from a developed country for irresponsible and often illegal disposal in a developing country. Now, with the industrialization and globalization of China and other developing countries, environmental dumping can involve both developing and developed countries as origin and destination. This dumping can be especially harmful to attempts to control under the Montreal Protocol ozone-depleting and climate-forcing chemical substances and/or products requiring unnecessarily high energy consumption. While developing country Parties to the Montreal Protocol are allowed to delay their phasedown of climate-forcing and ozone-depleting hydrofluorocarbons (HFCs) during a multi-year grace period, there are advantages to earlier implementation when superior alternatives are already available at reasonable costs, as is the case for many uses of HFCs today. Thus, developing countries can benefit under the Protocol from setting controls for environmental dumping. This article aims to give policymakers, especially those in developing countries, a legal and policy “toolkit” that can be used to stop unwanted environmental dumping. It includes an examination of the history of environmental dumping, illustration of such dumping in practice, a detailed explanation and examination of the legal and policy tools, and a summary of the consequences of environmental dumping

Expanding subjectivities:Introduction to the special issue on ‘New directions in psychodynamic research’

A major theme in recent psychoanalytic thinking concerns the use of therapist subjectivity, especially “countertransference,” in understanding patients. This thinking converges with and expands developments in qualitative research regarding the use of researcher subjectivity as a tool to understanding, especially but not exclusively in observational and interview-based studies. Psychodynamic or psychoanalytic approaches to research add an emphasis on unconscious motivational processes in both researchers and research participants that impact research experience and data. Building upon Anglo-Saxon and continental traditions, this special issue provides examples of the use of researcher subjectivity, informed by psychoanalytic thinking, in expanding research understanding