The role of financing in international trade during good times and bad

The collapse of trade during the financial crisis can be tied, for the most part, to a drop in demand. Less talked about, however, is the role of financing—or lack thereof.International trade

Landscapes of data sets and functoriality of persistent homology

The aim of this article is to describe a new perspective on functoriality of persistent homology and explain its intrinsic symmetry that is often overlooked. A data set for us is a finite collection of functions, called measurements, with a finite domain. Such a data set might contain internal symmetries which are effectively captured by the action of a set of the domain endomorphisms. Different choices of the set of endomorphisms encode different symmetries of the data set. We describe various category structures on such enriched data sets and prove some of their properties such as decompositions and morphism formations. We also describe a data structure, based on coloured directed graphs, which is convenient to encode the mentioned enrichment. We show that persistent homology preserves only some aspects of these landscapes of enriched data sets however not all. In other words persistent homology is not a functor on the entire category of enriched data sets. Nevertheless we show that persistent homology is functorial locally. We use the concept of equivariant operators to capture some of the information missed by persistent homology

Exploiting the Hierarchical Morphology of Single-Walled and Multi-Walled Carbon Nanotube Films for Highly Hydrophobic Coatings

Self-assembled hierarchical solid surfaces are very interesting for wetting phenomena, as observed in a variety of natural and artificial surfaces. Here, we report single-walled (SWCNT) and multi-walled carbon nanotube (MWCNT) thin films realized by a simple, rapid, reproducible, and inexpensive filtration process from an aqueous dispersion, that was deposited at room temperature by a dry-transfer printing method on glass. Furthermore, the investigation of carbon nanotube films through scanning electron microscopy (SEM) reveals the multi-scale hierarchical morphology of the self-assembled carbon nanotube random networks. Moreover, contact angle measurements show that hierarchical SWCNT/MWCNT composite surfaces exhibit a higher hydrophobicity (contact angles of up to 137{\deg}) than bare SWCNT (110{\deg}) and MWCNT (97{\deg}) coatings, thereby confirming the enhancement produced by the surface hierarchical morphology.Comment: 7 pages, 5 figures, This article is part of the Thematic Series "Self-assembly of nanostructures and nanomaterials

Super-Hydrophobic Multi-Walled Carbon Nanotube Coatings for Stainless Steel

We have taken advantage of the native surface roughness and the iron content of AISI 316 stainless steel to direct grow multi-walled carbon nanotube (MWCNT) random networks by chemical vapor deposition (CVD) at low-temperature ($< 1000^{\circ}$C), without the addition of any external catalysts or time-consuming pre-treatments. In this way, super-hydrophobic MWCNT films on stainless steel sheets were obtained, exhibiting high contact angle values ($154^{\circ}$) and high adhesion force (high contact angle hysteresis). Furthermore, the investigation of MWCNT films at scanning electron microscopy (SEM) reveals a two-fold hierarchical morphology of the MWCNT random networks made of hydrophilic carbonaceous nanostructures on the tip of hydrophobic MWCNTs. Owing to the Salvinia effect, the hydrophobic and hydrophilic composite surface of the MWCNT films supplies a stationary super-hydrophobic coating for conductive stainless steel. This biomimetical inspired surface not only may prevent corrosion and fouling but also could provide low-friction and drag-reduction.Comment: 6 pages, 3 figure

On-glass optoelectronic platform for on-chip detection of DNA

Lab-on-chip are analytical systems which, compared to traditional methods, offer significant reduction of sample, reagent, energy consumption and waste production. Within this framework, we report on the development and testing of an optoelectronic platform suitable for the on-chip detection of fluorescent molecules. The platform combines on a single glass substrate hydrogenated amorphous silicon photosensors and a long pass interferential filter. The design of the optoelectronic components has been carried out taking into account the spectral properties of the selected fluorescent molecule. We have chosen the [Ru(phen)2(dppz)]2+ which exhibits a high fluorescence when it is complexed with nucleic acids in double helix. The on-glass optoelectronic platform, coupled with a microfluidic network, has been tested in detection of double-stranded DNA (dsDNA) reaching a detection limit as low as 10 ng/μL

Distortions in farmer prices since the 1950s: South Africa in international perspective

For decades, earnings from farming in many low-income countries have been depressed by a pro-urban bias in own-country policies, as well as by governments of richer countries favoring their farmers with import barriers and subsidies. Both sets of policies reduce national and global economic growth. They also add to inequality and poverty in developing countries, since most of the worldÂ’s billion poorest people depend on farming for their livelihood. Over the past two decades numerous developing country governments have reduced their sectoral and trade policy distortions, while some high-income countries also have begun reforming their protectionist policies. Drawing on results from a new multi-country research project, this paper examines the extent of South AfricaÂ’s reforms relative to those of other temperate-zone Southern Hemisphere countries, of Northern Hemisphere rich countries, and of other developing countries. It concludes by pointing to the scope and prospects for further pro-poor policy reform at home and abroad.Distorted incentives, agricultural and trade policy reforms

Disease and Disorders of Freshwater Unionid Mussels: A Brief Overview of Recent Studies

The use of aquatic invertebrates in biomedical research and as environmental sentinels has dramatically grown in recent decades, with an increased need in understanding of comparative pathology. The Unionids freshwater mussels are a group of worldwide distributed bivalves residing small ditches and ponds, lakes, canals and rivers, often used as animal test in eco-toxicological studies. Once one of the most abundant bivalve molluscs in ancient rivers around the world, now many of them are declining in many countries and consequently are nearly extinct in many areas. The causes of this decline are not fully understood but alteration and degradation of the freshwater habitat seemed to play a central role. To date, link causality to the observed losses during episode of mussel die-offs has been more difficult to establish, and disease and pathogen presence have been scarcely considered. In this article we provide a brief overview of unionids freshwater mussel conservation status, also describing reported diseases and pathogens and illustrating a few relatively well-documented studies

Geochemical and mineralogical datasets on waters and stream precipitates from an abandoned mining site: Montevecchio-Ingurtosu district, Rio Irvi (SW Sardinia)

Geochemical modelling data and Powder X-Ray Diffraction data on samples collected along Rio Irvi (Montevecchio-Ingurtosu mining district, SW Sardinia, Italy) are reported in this paper. The data show the results of data processing to calculate water chemical speciation of ions and saturation indices of relevant mineral phases. These data are related with the research article: De Giudici G. et al (2018), Application of hydrologic-tracer techniques to the Casargiu adit and Rio Irvi (SW-Sardinia, Italy): Using enhanced natural attenuation to reduce extreme metal loads, Applied Geochemistry, vol.96, 42–54. The comparison of the calculated saturation indices of relevant Fe-bearing phases with the PXRD data of samples collected along the stream confirm the quality of the SI dataset and the good correlation between the calculations and the observed data. The comparison of this dataset with others can help to deeper understand and quantify the impact of past and current mining activity on water bodies, contributing to implement the scientific background for the application of remediation actions

Integration of amorphous silicon balanced photodiodes and thin film heaters for biosensing application

This work presents the development and testing of an integrated system for on-chip detection of thermochemiluminescent biomolecules. The activation energy of the reaction is provided by a transparent structure of thin film heaters deposited on one side of a glass substrate. Light, passing through the substrate, reaches an array of amorphous silicon differential structure deposited on the opposite side of the glass substrate. The structure is designed to perform differential current measurements between a light- shielded diode, whose current is sensitive only to temperature, and a photosensor, sensitive to both incident light and temperature. The device therefore balances the thermal variations of the photodiode current and reduces the dark-current noise. These features make the presented system very appealing as highly miniaturized micro-analytical devices for biosensing applications

Positive motherhood at work: the role of supervisor support in return to work after maternity leave

Cognitive factors can strongly influence mothers’ well-being. Maternal beliefs about societal expectations, role identity, maternal confidence, and concern about being a good or bad parent threaten maternal well-being, especially if these beliefs are irrational, inflexible, and strict. Moreover, they can negatively influence the critical time of returning to work after maternity leave. As stated by the conservation of resources theory, people may become more irrational when their resources are exhausted, with detrimental effects on individual well-being. To protect and enhance well-being, working mothers should draw upon additional resources, including their organizational contexts. In this regard, a key figure is the supervisor, whose positive behaviours and stable support can improve working mothers’ well-being and facilitate their effective return to work after maternity leave. This study aims at examining the relation between the rigidity of maternal beliefs and well-being (namely, general health, job satisfaction, and job performance), hypothesizing the mediation effect of perceived supervisor support during return to work after maternity leave. The Rigidity of Maternal Beliefs Scale, the measure for Supervisors to Support Return to Work, and the General Health Questionnaire were used together with a two-item measure for examining job performance and a single-item measure for measuring job satisfaction. The questionnaire was completed by 216 mothers. We tested the hypotheses by means of structural equation models with latent variables, using the Lisrel 8.80 software. Findings show that rigidity of maternal beliefs is associated with perceived supervisor support during return to work, which, in turn, is associated with working mothers’ general health, job satisfaction, and job performance. Consequently, perceived supervisor support during return to work totally mediates the relations between the rigidity of maternal beliefs and the outcomes considered. Results underline the centrality of supervisor perceived negative behaviors in sustaining working mothers after the long-term leave, when irrational beliefs regarding motherhood threaten their well-being. Practical implications for HR management are discussed