SOME FALLACIES IN AGRICULTURAL ECONOMICS: A MACROECONOMIC INTERPRETATION

Teaching/Communication/Extension/Profession,

Erratum: algebraic spin liquid as the mother of many competing orders

We correct an error in our paper Phys. Rev. B 72, 104404 (2005) [cond-mat/0502215]. We show that a particular fermion bilinear is not related to the other ``competing orders'' of the algebraic spin liquid, and does not possess their slowly decaying correlations. For the square lattice staggered flux spin liquid (equivalently, d-wave RVB state), this observable corresponds to the uniform spin chirality.Comment: 1.25 page

Towards Verifiably Ethical Robot Behaviour

Ensuring that autonomous systems work ethically is both complex and difficult. However, the idea of having an additional `governor' that assesses options the system has, and prunes them to select the most ethical choices is well understood. Recent work has produced such a governor consisting of a `consequence engine' that assesses the likely future outcomes of actions then applies a Safety/Ethical logic to select actions. Although this is appealing, it is impossible to be certain that the most ethical options are actually taken. In this paper we extend and apply a well-known agent verification approach to our consequence engine, allowing us to verify the correctness of its ethical decision-making.Comment: Presented at the 1st International Workshop on AI and Ethics, Sunday 25th January 2015, Hill Country A, Hyatt Regency Austin. Will appear in the workshop proceedings published by AAA

The Evolution of the America Perception of Lobster from the 17th to the 21st Century

Lobster early in American history was a low class food commonly served to servants and slaves. Technological advancements, and scarcity during World War II are what facilitated preservation of fresh lobster drove the cultural shift behind the elevated status of the American Lobster

Algebraic spin liquid as the mother of many competing orders

We study the properties of a class of two-dimensional interacting critical states -- dubbed algebraic spin liquids -- that can arise in two-dimensional quantum magnets. A particular example that we focus on is the staggered flux spin liquid, which plays a key role in some theories of underdoped cuprate superconductors. We show that the low-energy theory of such states has much higher symmetry than the underlying microscopic spin system. This symmetry has remarkable consequences, leading in particular to the unification of a number of seemingly unrelated competing orders. The correlations of these orders -- including, in the staggered flux state, the Neel vector and the order parameter for the columnar and box valence-bond solid states -- all exhibit the SAME slow power-law decay. Implications for experiments in the pseudogap regime of the cuprates and for numerical calculations on model systems are discussed.Comment: Minor changes; final published version. 17 pages, 3 figure

Monopoles in CP(N-1) model via the state-operator correspondence

One of the earliest proposed phase transitions beyond the Landau-Ginzburg-Wilson paradigm is the quantum critical point separating an antiferromagnet and a valence-bond-solid on a square lattice. The low energy description of this transition is believed to be given by the 2+1 dimensional CP(1) model -- a theory of bosonic spinons coupled to an abelian gauge field. Monopole defects of the gauge field play a prominent role in the physics of this phase transition. In the present paper, we use the state-operator correspondence of conformal field theory in conjunction with the 1/N expansion to study monopole operators at the critical fixed point of the CP(N-1) model. This elegant method reproduces the result for monopole scaling dimension obtained through a direct calculation by Murthy and Sachdev. The technical simplicity of our approach makes it the method of choice when dealing with monopole operators in a conformal field theory.Comment: 14 pages, 1 figur

Factors Influencing Energy Intensity in Four Chinese Industries

In this paper, we investigate the determinants of decline in energy intensity in four Chinese industries - pulp and paper, cement, iron and steel, and aluminum. This paper attempts to answer the following key question: For the purpose of promoting energy efficiency, do prices, technology, enterprise restructuring and other policy-related instruments affect various sectors uniformly so as to justify uniform industrial energy conservation policies, or do different industries respond significantly differently so as to require policies that are tailored to each sector separately? In this paper, we examine this question using data for China\u27s most energy-intensive large and medium-size enterprises over the period 1999-2004. Our results suggest that in all four industries rising energy costs are a significant contributor to the decline in energy intensity over our period of study. China\u27s industrial policies encouraging consolidations and scale economies also seem to have contributed to reductions in energy intensity in these four industries

The Importance of Institutional Design for Distributed Local-Level Governance of Groundwater: The Case of California’s Sustainable Groundwater Management Act

In many areas of the world, groundwater resources are increasingly stressed, and unsustainable use has become common. Where existing mechanisms for governing groundwater are ineffective or nonexistent, new ones need to be developed. Local level groundwater governance provides an intriguing alternative to top-down models, with the promise of enabling management to better match the diversity of physical and social conditions in groundwater basins. One such example is emerging in California, USA, where new state law requires new local agencies to self-organize and act to achieve sustainable groundwater management. In this article, we draw on insights from research on common pool resource management and natural resources governance to develop guidelines for institutional design for local groundwater governance, grounded in California’s developing experience. We offer nine criteria that can be used as principles or standards in the evaluation of institutional design for local level groundwater governance: scale, human capacity, funding, authority, independence, representation, participation, accountability, and transparency. We assert that local governance holds promise as an alternative to centralized governance in some settings but that its success will depend heavily on the details of its implementation. Further, for local implementation to achieve its promise, there remain important complementary roles for centralized governance. California’s developing experience with local level groundwater management in dozens of basins across the state provides a unique opportunity to test and assess the importance and influence of these criteria