The symmetry of the spin Hamiltonian in herbertsmithite, a spin-1/2 kagom\'{e} lattice

We present magnetization measurements on oriented powder of ZnCu$_{3}$(OH)$_{6}$Cl$_{2}$ along and perpendicular to the orienting field. We find a dramatic difference in the magnetization between the two directions. It is biggest at low measurement fields $H$ or high temperatures. We show that the difference at high temperatures must emerge from Ising-like exchange anisotropy. This allows us to explain muon spin rotation data at $T\to 0$ in terms of an exotic ferromagnetic ground state.Comment: 5 pages, 5 figure

Sex Work and City Planning: Winnipeg’s Red Light District Committee and the Regulation of Prostitution

In November of 1999, a Manitoba Provincial Court decision called into question the City of Winnipeg’s ability to regulate off-street prostitution through its municipal licencing by-law for escort services. The result was a lengthy process that saw the city establish a volunteer committee to investigate the regulation of the sex trade in Winnipeg and make recommendations about what could be done in the future. This paper examines the process by which the volunteer committee arrived at its recommendations, and the resulting response from city bureaucrats and officials within the provincial Department of Justice. In the end, most of the committee’s recommendations did not result in any concrete action by the city or province, and perhaps the most significant one – the creation of a new city by-law to regulate the industry – is, nearly two years later, still in the planning phase. In the meantime, the province has put into place a tough new law to deal with the sex and drug trade. At present, the city has yet to address the key concern of the court decision that began the process over three years ago: the development of a clear set of regulations for an industry badly in need of closer monitoring and supervision

Looking back: understanding visits to museums in the UK and beyond since the nineteenth century

This editorial introduces the second of two special issues of Cultural Trends dedicated to identifying and interpreting numbers of visits to museums since the nineteenth century. The first exclusively considered UK museums – English museums, in particular. The present issue adds to that coverage of museum visiting in England, Wales and Scotland, as well as addressing visiting in France, Australia and New Zealand. The editorial reflects on the transnational and global dynamics that shaped the development and counting of museum visits

31P NMR study of Na2CuP2O7: a S=1/2 two-dimensional Heisenberg antiferromagnetic system

The magnetic properties of Na2CuP2O7 were investigated by means of 31P nuclear magnetic resonance (NMR), magnetic susceptibility, and heat capacity measurements. We report the 31P NMR shift, the spin-lattice 1/T1, and spin-spin 1/T2 relaxation-rate data as a function of temperature T. The temperature dependence of the NMR shift K(T) is well described by the S=1/2 square lattice Heisenberg antiferromagnetic (HAF) model with an intraplanar exchange of J/k_B \simeq 18\pm2 K and a hyperfine coupling A = (3533\pm185) Oe/mu_B. The 31P NMR spectrum was found to broaden abruptly below T \sim 10 K signifying some kind of transition. However, no anomaly was noticed in the bulk susceptibility data down to 1.8 K. The heat capacity appears to have a weak maximum around 10 K. With decrease in temperatures, the spin-lattice relaxation rate 1/T1 decreases monotonically and appears to agree well with the high temperature series expansion expression for a S = 1/2 2D square lattice.Comment: 12 pages, 8 figures, submitted to J. Phys.: Cond. Ma

Collaborative conservation planning : Quantifying the contribution of expert engagement to identify spatial conservation priorities

The importance of expert input to spatial conservation prioritization outcomes is poorly understood. We quantified the impacts of refinements made during consultation with experts on spatial conservation prioritization of Christmas Island. There was just 0.57 correlation between the spatial conservation priorities before and after consultation, bottom ranked areas being most sensitive to changes. The inclusion of a landscape condition layer was the most significant individual influence. Changes (addition, removal, modification) to biodiversity layers resulted in a combined 0.2 reduction in correlation between initial and final solutions. Representation of rare species in top ranked areas was much greater after expert consultation; representation of widely distributed species changed relatively little. Our results show how different inputs have notably different impacts on the final plan. Understanding these differences helps plan time and resources for expert consultation.Peer reviewe

Cannabidiol activates PINK1-Parkin-dependent mitophagy and mitochondrial-derived vesicles

The PINK1/Parkin pathway plays an important role in maintaining a healthy pool of mitochondria. Activation of this pathway can lead to apoptosis, mitophagy, or mitochondrial-derived vesicle formation, depending on the nature of mitochondrial damage. The signaling by which PINK/Parkin activation leads to these different mitochondrial outcomes remains understudied. Here we present evidence that cannabidiol (CBD) activates the PINK1-Parkin pathway in a unique manner. CBD stimulates PINK1-dependent Parkin mitochondrial recruitment similarly to other well-studied Parkin activators but with a distinctive shift in the temporal dynamics and mitochondrial fates. The mitochondrial permeability transition pore inhibitor cyclosporine A exclusively diminished the CBD-induced PINK1/Parkin activation and its associated mitochondrial effects. Unexpectedly, CBD treatment also induced elevated production of mitochondrial-derived vesicles (MDV), a potential quality control mechanism that may help repair partial damaged mitochondria. Our results suggest that CBD may engage the PINK1-Parkin pathway to produce MDV and repair mitochondrial lesions via mitochondrial permeability transition pore opening. This work uncovered a novel link between CBD and PINK1/Parkin-dependent MDV production in mitochondrial health regulation

The impact of broadband in schools

The report reviews evidence for the impact of broadband in English schools, exploring; Variations in provision in level of broadband connectivity; Links between the level of broadband activity and nationally accessible performance data; Aspects of broadband connectivity and the school environment that contribute to better outcomes for pupils and teachers; Academic and motivational benefits associated with educational uses of this technology

Spin-gap behaviour in the 2-leg spin-ladder BiCu2PO6

We present magnetic suscceptibility and heat capacity data on a new S=1/2 two-leg spin ladder compound BiCu2PO6. From our susceptibility analysis, we find that the leg coupling J1/k_B is ~ 80 K and the ratio of the rung to leg coupling J2/J1 ~ 0.9. We present the magnetic contribution to the heat capacity of a two-leg ladder. The spin-gap Delta/k_B =3 4 K obtained from the heat capacity agrees very well with that obtained from the magnetic susceptibility. Significant inter-ladder coupling is suggested from the susceptibility analysis. The hopping integrals determined using Nth order muffin tin orbital (NMTO) based downfolding method lead to ratios of various exchange couplings in agreement with our experimental data. Based on our band structure analysis, we find the inter-ladder coupling in the bc-plane J2 to be about 0.75J1 placing the compound presumably close to the quantum critical limit.Comment: 8 pages, 5 figure

Synthesis, Structure and Properties of Tetragonal Sr2M3As2O2 (M3 = Mn3, Mn2Cu and MnZn2) Compounds Containing Alternating CuO2-Type and FeAs-Type Layers

Polycrystalline samples of Sr2Mn2CuAs2O2, Sr2Mn3As2O2, and Sr2Zn2MnAs2O2 were synthesized. Their temperature- and applied magnetic field-dependent structural, transport, thermal, and magnetic properties were characterized by means of x-ray and neutron diffraction, electrical resistivity rho, heat capacity, magnetization and magnetic susceptibility measurements. These compounds have a body-centered-tetragonal crystal structure (space group I4/mmm) that consists of MO2 (M = Zn and/or Mn) oxide layers similar to the CuO2 layers in high superconducting transition temperature Tc cuprate superconductors, and intermetallic MAs (M = Cu and/or Mn) layers similar to the FeAs layers in high-Tc pnictides. These two types of layers alternate along the crystallographic c-axis and are separated by Sr atoms. The site occupancies of Mn, Cu and Zn were studied using Rietveld refinements of x-ray and neutron powder diffraction data. The temperature dependences of rho suggest metallic character for Sr2Mn2CuAs2O2 and semiconducting character for Sr2Mn3As2O2 and Sr2Zn2MnAs2O2. Sr2Mn2CuAs2O2 is inferred to be a ferrimagnet with a Curie temperature TC = 95(1) K. Remarkably, we find that the magnetic ground state structure changes from a G-type antiferromagnetic structure in Sr2Mn3As2O2 to an A-type ferrimagnetic structure in Sr2Mn2CuAs2O2 in which the Mn ions in each layer are ferromagnetically aligned, but are antiferromagnetically aligned between layers.Comment: 18 pages, 16 figures, 6 tables; submitted to Phys. Rev.