Symmetries and solutions of field equations of axion electrodynamics

The group classification of models of axion electrodynamics with arbitrary self interaction of axionic field is carried out. It is shown that extensions of the basic Poincar\'e invariance of these models appear only for constant and exponential interactions. The related conservation laws are discussed. Using the In\"on\"u-Wigner contraction the non-relativistic limit of equations of axion electrodynamics is found. An extended class of exact solutions for the electromagnetic and axion fields is obtained. Among them there are solutions including up to six arbitrary functions. In particular, solutions which describe propagation with velocities faster than the velocity of light are found. These solutions are smooth and bounded functions which correspond to positive definite and bounded energy density.Comment: New section 6 ia added where the superluminal propagation velocities are discusse

Galilei-invariant equations for massive fields

Galilei-invariant equations for massive fields with various spins have been found and classified. They have been derived directly, i.e., by using requirement of the Galilei invariance and various facts on representations of the Galilei group deduced in the paper written by de Montigny M, Niederle J and Nikitin A G, J. Phys. A \textbf{39}, 1-21, 2006. A completed list of non-equivalent Galilei-invariant wave equations for vector and scalar fields is presented. It shows two things. First that the collection of such equations is very broad and describes many physically consistent systems. In particular it is possible to describe spin-orbit and Darwin couplings in frames of Galilei-invariant approach. Second, these Galilei-invariant equations can be obtained either via contraction of known relativistic equations or via contractions of quite new relativistic wave equations.Comment: Minor improvements of the text has been made and misprints are correcte

Public policies to support agroecology in Latin America and the Caribbean

Latin American agroecology proposes a transformation of conventional agri-food systems. It is driven by social movements that have succeeded in forming coalitions that have promoted its integration into public policies. These policies involve a range of instruments that are often embedded in programmes that also support organic agriculture and sustainable agriculture. However, while these two types of agriculture propose more ecological practices, they do not question the basis of the conventional agri-food system. The implementation of instruments to support agroecology therefore depends on the power relations established within each country. This Perspective analyses these policies and their influence on the development of agroecology in eight countries: Argentina, Brazil, Chile, Costa Rica, Cuba, El Salvador, Mexico, and Nicaragua. These policies remain fragile, while support for large-scale conventional agriculture is still predominant. Their challenge is therefore to convince more broadly farmers, consumers and policymakers about the importance of issues such as public health and food security

Emirati women do not shy away from competition: evidence from a patriarchal society in transition

We explore gender attitudes towards competition in the United Arab Emirates—a traditionally patriarchal society which in recent times has adopted numerous policies to empower women and promote their role in the labor force. The experimental treatments vary whether individuals compete in single-sex or mixed-sex groups. In contrast to previous studies, women in our sample are not less willing to compete than men. In fact, once we control for individual performance, Emirati women are more likely to select into competition. Our analysis shows that neither women nor men shy away from competition, and both compete more than what would be optimal in monetary terms as the fraction of men in their group increases. We offer a detailed survey of the literature and discuss possible reasons for the lack of gender differences in our experiment

Cabozantinib in progressive medullary thyroid cancer

Purpose Cabozantinib, a tyrosine kinase inhibitor (TKI) of hepatocyte growth factor receptor (MET), vascular endothelial growth factor receptor 2, and rearranged during transfection (RET), demonstrated clinical activity in patients with medullary thyroid cancer (MTC) in phase I. Patients and Methods We conducted a double-blind, phase III trial comparing cabozantinib with placebo in 330 patients with documented radiographic progression of metastatic MTC. Patients were randomly assigned (2:1) to cabozantinib (140 mg per day) or placebo. The primary end point was progression-free survival (PFS). Additional outcome measures included tumor response rate, overall survival, and safety. Results The estimated median PFS was 11.2 months for cabozantinib versus 4.0 months for placebo (hazard ratio, 0.28; 95% CI, 0.19 to 0.40; P < .001). Prolonged PFS with cabozantinib was observed across all subgroups including by age, prior TKI treatment, and RET mutation status (hereditary or sporadic). Response rate was 28% for cabozantinib and 0% for placebo; responses were seen regardless of RET mutation status. Kaplan-Meier estimates of patients alive and progression-free at 1 year are 47.3% for cabozantinib and 7.2% for placebo. Common cabozantinib-associated adverse events included diarrhea, palmar-plantar erythrodysesthesia, decreased weight and appetite, nausea, and fatigue and resulted in dose reductions in 79% and holds in 65% of patients. Adverse events led to treatment discontinuation in 16% of cabozantinib-treated patients and in 8% of placebo-treated patients. Conclusion Cabozantinib (140 mg per day) achieved a statistically significant improvement of PFS in patients with progressive metastatic MTC and represents an important new treatment option for patients with this rare disease. This dose of cabozantinib was associated with significant but manageable toxicity

Understanding fear of opportunism in global prize-based science contests: Evidence for gender and age differences

Global prize-based science contests have great potential for tapping into diverse knowledge on a global scale and overcoming important scientific challenges. A necessary step for knowledge to be utilized in these contests is for that knowledge to be disclosed. Knowledge disclosure, however, is paradoxical in nature: in order for the value of knowledge to be assessed, inventors must disclose their knowledge, but then the person who receives that knowledge does so at no cost and may use it opportunistically. This risk of potential opportunistic behavior in turn makes the inventor fearful of disclosing knowledge, and this is a major psychological barrier to knowledge disclosure. In this project, we investigated this fear of opportunism in global prize-based science contests by surveying 630 contest participants in the InnoCentive online platform for science contests. We found that participants in these science contests experience fear of opportunism to varying degrees, and that women and older participants have significantly less fear of disclosing their scientific knowledge. Our findings highlight the importance of taking differences in such fears into account when designing global prize-based contests so that the potential of the contests for reaching solutions to important and challenging problems can be used more effectively