A signature invariant for knotted Klein graphs

We define some signature invariants for a class of knotted trivalent graphs using branched covers. We relate them to classical signatures of knots and links. Finally, we explain how to compute these invariants through the example of Kinoshita's knotted theta graph.Comment: 23 pages, many figures. Comments welcome ! Historical inaccuracy fixe

The ‘Trendiness’ of Sleep: An Empirical Investigation into the Cyclical Nature of Sleep Time

Using Canadian time use data, we exploit exogenous variation in local unemployment rates to investigate the cyclical nature of sleep time and show that for both men and women, sleep time decreases when the economy is doing relatively better. Our results suggest that in a recession Canadians sleep an average of 2 hours and 34 minutes more per week, or 22 minutes more per day. Given the importance of even small changes in sleep time on measures of cognitive functioning such as reaction time and concentration, our findings may help explain the countercyclical nature of mortality. Further, as we find that sleep is affected by the same economic variables (notably the unemployment rate) that affect market work time, our results also contribute to the limited literature that shows that sleep time should not be treated as exogenously determined, but, like any other resource, determined by its relative cost.Business Cycles, Sleep.

Selective gas phase hydrogenation of nitroarenes over Mo2C-supported Au–Pd

Open Access via RSC Gold 4 Gold Financial support to Dr. X. Wang through the Overseas Research Students Award Scheme (ORSAS) is acknowledged. Dr. N. Perret also acknowledges financial support from COST Action MP0903 Nanoalloys.Peer reviewedPublisher PD

Preserving vertical co-ordination in the West African cotton sector

In this paper, we defend the idea that in the African context, non-market co-operation between farmers and ginning companies outperforms market transactions. In the absence of a reliable legal mechanism, market liberalization threatens the sustainability of contractual agreements between farmers and cotton companies. We present alternatives to the full market competition option and to the public monopoly organization that allow the production contract to be preserved. Special attention is paid to the case of Burkina Faso where efficiency gains have been obtained thanks to the strengthening of farmers' organizations and their financial participation in the cotton company.yardstick competition, zoning –, markets failure –, Contract farming –, West Africa –, Cotton –

The Economic Consequences of Export Instability in Developing Countries: A Survey

In this note we provide a brief survey of the literature about the effects of exports instability in developing countries, mainly focused on commodity dependent economies. Whatever the nature of instability, exports instability generate major disturbances in those economies. Exports instability is often considered as a major source of macroeconomic instability that is welfare costly. Exports instability is also risk generating for individual economic agents who take it into account in their economic decisions but cannot get rid of it in the absence of appropriate credit and insurance devices. We thus examine the macroeconomic consequences of export instability, first in the short term, using the Dutch Disease framework, and second its effects on growth. We then examine the effects of instability from a microeconomic point of view.

The effect of devaluation on cattle markets integration in Burkina Faso

The aim of this paper is to highlight an aspect of devaluation that is generally ignored in the literature, namely, its positive impact on domestic trade. We develop a parity bounds model for cattle markets of Burkina Faso with two regimes of prices, autarkic and integrated, consistent with spatial and inter-temporal arbitrage conditions. When markets are autarkic, prices follow a random walk and when markets are integrated, prices are equal up to transaction costs. The integrated regime is more likely when transaction costs are low. In our model, the 1994 franc CFA devaluation reduces transaction costs relatively to cattle prices, thereby promoting markets integration. The model is tested using a switching regression with exogenous selection variables. The results show that the probability of market integration significantly increased after the devaluation.panel data., switching regression model, burkina faso, franc CFA devaluation, cattle, inter-temporal arbitrage, Market integration

Devaluation and Cattle Markets Integration in Burkina Faso

The aim of this paper is to highlight an aspect of devaluation that is generally ignored in the literature, namely, its positive impact on domestic trade. We develop a parity bounds model for cattle markets of Burkina Faso with two regimes of prices, autarkic and integrated, consistent with spatial and inter-temporal arbitrage conditions. When markets are autarkic, prices follow a random walk and when markets are integrated, prices are equal up to transaction costs. The integrated regime is more likely when transaction costs are low. In our model, the 1994 franc CFA devaluation reduces transaction costs relatively to cattle prices, thereby promoting markets integration. The model is tested using a switching regression with exogenous selection variables. The results show that the probability of market integration significantly increased after the devaluation.panel data., switching regression model, burkina faso, franc CFA devaluation, cattle, inter-temporal arbitrage, Market integration

Dynamic Acetylation of All Lysine 4–Methylated Histone H3 in the Mouse Nucleus: Analysis at c-fos and c-jun

A major focus of current research into gene induction relates to chromatin and nucleosomal regulation, especially the significance of multiple histone modifications such as phosphorylation, acetylation, and methylation during this process. We have discovered a novel physiological characteristic of all lysine 4 (K4)–methylated histone H3 in the mouse nucleus, distinguishing it from lysine 9–methylated H3. K4-methylated histone H3 is subject to continuous dynamic turnover of acetylation, whereas lysine 9–methylated H3 is not. We have previously reported dynamic histone H3 phosphorylation and acetylation as a key characteristic of the inducible proto-oncogenes c-fos and c-jun. We show here that dynamically acetylated histone H3 at these genes is also K4-methylated. Although all three modifications are proven to co-exist on the same nucleosome at these genes, phosphorylation and acetylation appear transiently during gene induction, whereas K4 methylation remains detectable throughout this process. Finally, we address the functional significance of the turnover of histone acetylation on the process of gene induction. We find that inhibition of turnover, despite causing enhanced histone acetylation at these genes, produces immediate inhibition of gene induction. These data show that all K4-methylated histone H3 is subject to the continuous action of HATs and HDACs, and indicates that at c-fos and c-jun, contrary to the predominant model, turnover and not stably enhanced acetylation is relevant for efficient gene induction

Proximity-induced charge density wave in a metallic system

Non-local quasiparticles in correlated quantum materials can exhibit the proximity effect. For instance, in metal superconductor hybrid systems, the leaking of cooper pairs to the metallic region induces superconducting correlations in a standard metal. This paper explores the proximity effects of charge density wave (CDW) on metal using the attractive Hubbard model, which harbors CDW state at half-filling. Our fully self-consistent calculations demonstrate that periodic charge modulations develop in a metal due to the tunneling of finite momentum particle-hole pairs from the CDW region. Upon doping the normal region, the commensurate CDW changes to an incommensurate one by incorporating regular phase shifts. Furthermore, the induced CDW produces a soft gap in the density of states and thus can be detected in tunneling experiments. We discuss our results in light of recent reports of such proximity-induced charge order in different two-dimensional heterostructures.Comment: 8 Pages, 6 Figure