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\"In the wake of the 2008 global financial crisis, the regulation of the world's enormous derivatives markets assumed center stage on the international public policy agenda. Critics argued that loose regulation had contributed to the momentous crisis as well as commodity price volatility, market abuse, and, more generally, the growing power and influence of private financial interests. What has been done since 2008 to reform the regulation of derivatives markets? This volume examines how the G20 governments developed a coordinated international agenda to enhance public regulatory control over these markets that had been allowed to grow largely unchecked before the crisis. At the same time, the analysis shows that the degree of change embodied in this post-2008 reform agenda should not be overstated. The G20 governments have focused primarily just on enhancing the transparency and resilience of the markets, and they have endorsed some continued delegation of key governance functions to private actors and private rule-making. Moreover, the implementation of the G20 reform agenda has been characterized by unanticipated delays and inconsistencies as well as conflict and regulatory fragmentation between G20 members. The volume shows how these post-crisis regulatory trends - both the emergence of the G20 reform agenda and the difficulties associated with its implementation - have been influenced by a complex combination of transnational, inter-state, and domestic political dynamics\"-- Provided by publisher.

A quantum spin liquid is a state of matter where unpaired electrons’ spins, although entangled, do not show magnetic order even at the zero temperature. The realization of a quantum spin liquid is a long-sought goal in condensed-matter physics. Although neutron scattering experiments on the two-dimensional spin-1/2 kagome lattice ZnCu3(OD)6Cl2 and triangular lattice YbMgGaO4 have found evidence for the hallmark of a quantum spin liquid at very low temperature (a continuum of magnetic excitations), the presence of magnetic and non-magnetic site chemical disorder complicates the interpretation of the data. Recently, the three-dimensional Ce3+ pyrochlore lattice Ce2Sn2O7 has been suggested as a clean, effective spin-1/2 quantum spin liquid candidate, but evidence of a spin excitation continuum is still missing. Here, we use thermodynamic, muon spin relaxation and neutron scattering experiments on single crystals of Ce2Zr2O7, a compound isostructural to Ce2Sn2O7, to demonstrate the absence of magnetic ordering and the presence of a spin excitation continuum at 35 mK. With no evidence of oxygen deficiency and magnetic/non-magnetic ion disorder seen by neutron diffraction and diffuse scattering measurements, Ce2Zr2O7 may be a three-dimensional pyrochlore lattice quantum spin liquid material with minimum magnetic and non-magnetic chemical disorder.

SignificanceThe identity of the order parameter of the hidden-order (HO) phase in the heavy fermion compound URu2Si2 remains a long-standing mystery. The HO phase is intimately related to the large-moment antiferromagnetic (LMAFM) phase that is induced under pressure. Although these two phases presumably have distinct order parameters, their transport and thermodynamic properties are nearly indistinguishable. The measurements reported herein reveal that the HO and LMAFM phase transitions are manifested differently in the uniaxial thermal expansion coefficients and uniaxial pressure derivatives of the transition temperature. These results suggest that an itinerant effective model should include band states of different orbital and magnetic characters, if it is to describe the differing responses of the competing ordered phases to uniaxial pressure. Thermal expansion, electrical resistivity, magnetization, and specific heat measurements were performed on URu2−xFexSi2 single crystals for various values of Fe concentration x in both the hidden-order (HO) and large-moment antiferromagnetic (LMAFM) regions of the phase diagram. Our results show that the paramagnetic (PM) to HO and LMAFM phase transitions are manifested differently in the thermal expansion coefficient. The uniaxial pressure derivatives of the HO/LMAFM transition temperature T0 change dramatically when crossing from the HO to the LMAFM phase. The energy gap also changes consistently when crossing the phase boundary. In addition, for Fe concentrations at xc ≈ 0.1, we observe two features in the thermal expansion upon cooling, one that appears to be associated with the transition from the PM to the HO phase and another one at lower temperature that may be due to the transition from the HO to the LMAFM phase.

Thermal expansion, electrical resistivity, magnetization, and specific heat measurements were performed on URu2—xFeₓSi₂ single crystals for various values of Fe concentration x in both the hidden-order (HO) and large-moment antiferromagnetic (LMAFM) regions of the phase diagram. Our results show that the paramagnetic (PM) to HO and LMAFM phase transitions are manifested differently in the thermal expansion coefficient. The uniaxial pressure derivatives of the HO/LMAFM transition temperature T₀ change dramatically when crossing from the HO to the LMAFM phase. The energy gap also changes consistently when crossing the phase boundary. In addition, for Fe concentrations at xc ≈ 0.1, we observe two features in the thermal expansion upon cooling, one that appears to be associated with the transition from the PM to the HO phase and another one at lower temperature that may be due to the transition from the HO to the LMAFM phase.

Thermal expansion, electrical resistivity, magnetization, and specific heat measurements were performed on URu^sub 2-x^Fe^sub x^Si^sub 2^ single crystals for various values of Fe concentration x in both the hidden-order (HO) and large-moment antiferromagnetic (LMAFM) regions of the phase diagram. Our results show that the paramagnetic (PM) to HO and LMAFM phase transitions are manifested differently in the thermal expansion coefficient. The uniaxial pressure derivatives of the HO/LMAFM transition temperature T^sub 0^ change dramatically when crossing from the HO to the LMAFM phase. The energy gap also changes consistently when crossing the phase boundary. In addition, for Fe concentrations at x^sub c^ [asymptotically =] 0.1, we observe two features in the thermal expansion upon cooling, one that appears to be associated with the transition from the PM to the HO phase and another one at lower temperature that may be due to the transition from the HO to the LMAFM phase.

The identity of the order parameter of the hidden-order (HO) phase in the heavy fermion compound URu 2 Si 2 remains a long-standing mystery. The HO phase is intimately related to the large-moment antiferromagnetic (LMAFM) phase that is induced under pressure. Although these two phases presumably have distinct order parameters, their transport and thermodynamic properties are nearly indistinguishable. The measurements reported herein reveal that the HO and LMAFM phase transitions are manifested differently in the uniaxial thermal expansion coefficients and uniaxial pressure derivatives of the transition temperature. These results suggest that an itinerant effective model should include band states of different orbital and magnetic characters, if it is to describe the differing responses of the competing ordered phases to uniaxial pressure. Thermal expansion, electrical resistivity, magnetization, and specific heat measurements were performed on URu 2− x Fe x Si 2 single crystals for various values of Fe concentration x in both the hidden-order (HO) and large-moment antiferromagnetic (LMAFM) regions of the phase diagram. Our results show that the paramagnetic (PM) to HO and LMAFM phase transitions are manifested differently in the thermal expansion coefficient. The uniaxial pressure derivatives of the HO/LMAFM transition temperature T 0 change dramatically when crossing from the HO to the LMAFM phase. The energy gap also changes consistently when crossing the phase boundary. In addition, for Fe concentrations at x c ≈ 0.1, we observe two features in the thermal expansion upon cooling, one that appears to be associated with the transition from the PM to the HO phase and another one at lower temperature that may be due to the transition from the HO to the LMAFM phase.

A quantum spin liquid (QSL) is a state of matter where unpaired electrons' spins in a solid are quantum entangled, but do not show magnetic order in the zero-temperature limit. Because such a state may be important to the microscopic origin of high-transition temperature superconductivity and useful for quantum computation, the experimental realization of QSL is a long-sought goal in condensed matter physics. Although neutron scattering experiments on the two-dimensional (2D) spin-1/2 kagome-lattice ZnCu3(OD)6Cl2 and effective spin-1/2 triangular lattice YbMgGaO4 have found evidence for a continuum of magnetic excitations, the hallmark of a QSL carrying 'fractionalized quantum excitations', at very low temperature, magnetic and nonmagnetic site chemical disorder complicates the interpretation of the data. Recently, the three-dimensional (3D) Ce3+ pyrochlore lattice Ce2Sn2O7 has been suggested as a clean, effective spin-1/2 QSL candidate, but there is no evidence of a spin excitation continuum. Here we use thermodynamic, muon spin relaxation ( SR), and neutron scattering experiments on single crystals of Ce2Zr2O7, a compound isostructural to Ce2Sn2O7, to demonstrate the absence of magnetic ordering and the presence of a spin excitation continuum at 35 mK, consistent with the expectation of a QSL. Since our neutron diffraction and diffuse scattering measurements on Ce2Zr2O7 reveal no evidence of oxygen deficiency and magnetic/nonmagnetic ion disorder as seen in other pyrochlores, Ce2Zr2O7 may be the first example of a 3D QSL material with minimum magnetic and nonmagnetic chemical disorder.

The magnetic properties of Co thin films on silicon and magnetite single crystal substrates grown by electron beam evaporation were studied in situ in UHV using a superconducting quantum interference device magnetometer (UHVSQM). In this system, freshly deposited thin film samples from a separate molecular beam epitaxy (MBE) facility, were transported into the UHVSQM for magnetic characterization without breaking vacuum. The combination of the extremely high sensitivity of the SQUID for magnetic measurements with UHV surface analysis techniques offers the unique capability for films to be prepared, processed, and characterized repeatedly without substantial contamination. Magnetization isotherms as function of oxygen exposure on polycrystalline thin ferromagnetic (FM) Co layers indicate that the magnetic properties of these materials are profoundly altered as a result of oxidation and atmospheric contamination. In addition, field-cooled hysteresis loops performed at low temperatures indicate that the antiferromagnetic (AF) Co-oxide layer that result from the oxidation process is responsible for an induced exchange anisotropy in the FM Co films. The data indicates that interfacial roughness and non-uniform coupling across the interface may cause the AF to break up into a domain structure analogous to the one found in bulk FM materials. The resulting AF magnetic structure is apparently dependent on the competition between destabilizing forces at the interface when the FM layer moment's direction is reversed and stabilizing coercive forces within the AF domains. During the course of this research, we also investigated the effect of clean and oxidized Co layers on the magnetic properties of oriented single crystal$\\rm Fe\\sb3O\\sb4$films. These experiments were aimed in gaining an understanding of the underlying mechanism responsible for the large increase in coercivity$\\rm (H\\sb{c}),$and induced uniaxial anisotropy exhibited by this system as a result of the Co coverage. A systematic study suggests that a thin layer of Co $\\sp{2+}$ions is apparently responsible for an initial increase in$\\rm H\\sb{c}.$However, a second and much larger enhancement in$\\rm H\\sb{c}$occurs at low temperatures when these films evolve from a clean to an oxidized state. These observations constitute the first direct evidence for two separate mechanism, which strongly affect the magnetic properties of the$\\rm Fe\\sb3O\\sb4$films, and could be useful in deriving a model that satisfactorily describes the behavior of this system.

Arising from M. A. Nowak, C. E. Tarnita & E. O. Wilson 466, 1057-1062 (2010); Nowak et al. reply. Nowak et al. argue that inclusive fitness theory has been of little value in explaining the natural world, and that it has led to negligible progress in explaining the evolution of eusociality. However, we believe that their arguments are based upon a misunderstanding of evolutionary theory and a misrepresentation of the empirical literature. We will focus our comments on three general issues.

Approaches that are transdisciplinary and participatory can help to address complex socio-ecological issues by integrating multiple disciplinary perspectives while taking into account the different needs and experiences of community members and other stakeholders. Despite this promise, such approaches are rarely applied within the scientific community, as researchers and public actors often lack the training, practice and reference cases required to handle the working relationships and translations of terminology, ideas and values across multiple bodies of knowledge. A case study described in this manuscript depicts a group of researchers, artists and citizens consciously engaged in the construction of a transdisciplinary process as part of a 40-day ‘citizen science’ experiment focussed on assessing soil fertility in the urban area of Milan, Italy. The group drew from recognised scientific approaches, applied agronomic methodologies, artistic practices and technological tools, integrating them into a hybrid process of collective and participatory inquiry. As a quantitative outcome of the experiment, a dataset of bio-chemical parameters was generated, which was enriched by agronomic interpretations but also by artistic and reflective materials. Importantly, the process developed transdisciplinary and participatory skills, as it created a potentially replicable procedure of engagement, analysis and presentation for use in other citizen science settings. This article presents the context, the multiple objectives of the research and the applied approach and its timeline. Described in detail are the process of designing and conducting the experiment by involving an extended research community—including both junior and senior researchers—in progressive steps. Quantitative and qualitative results are provided. The findings are meant to contribute case material and methods to inform the advancement of transdisciplinary research approaches within the scientific community as well as examples of ways to transcend the boundaries of science to include artists and community stakeholders. The aspiration is to inform and inspire concrete application of transdisciplinary and participatory methods in concert to address complex socio-environmental challenges.