Honeylocust Twig-gall Midge (Diptera: Cecidomyiidae) in Michigan

Emergence and oviposition data were gathered for Neolasioptera brevis, a recently described pest of honeylocust. In 1984 the insects first emerged on 21 May and first oviposited on 4 June; in 1985 they first emerged on 28 April and first oviposited between 5-20 May. Average raceme length at emergence and at oviposition were 2.7 and 4.4 cm in 1984 and 2.6 and 4.8 cm in 1985. Approximate duration of the emergence period was one week. In 1985 observed oviposition wounds averaged 0.5/cm

Five Principles for Vertical Merger Enforcement Policy

There seems to be consensus that the Department of Justice’s 1984 Vertical Merger Guidelines do not reflect either modern theoretical and empirical economic analysis or current agency enforcement policy. Yet widely divergent views of preferred enforcement policies have been expressed among agency enforcers and commentators. Based on our review of the relevant economic literature and our experience analyzing vertical mergers, we recommend that the enforcement agencies adopt five principles: (i) The agencies should consider and investigate the full range of potential anticompetitive harms when evaluating vertical mergers; (ii) The agencies should decline to presume that vertical mergers benefit competition on balance in the oligopoly markets that typically prompt agency review, nor set a higher evidentiary standard based on such a presumption; (iii) The agencies should evaluate claimed efficiencies resulting from vertical mergers as carefully and critically as they evaluate claimed efficiencies resulting from horizontal mergers, and require the merging parties to show that the efficiencies are verifiable, merger-specific and sufficient to reverse the potential anticompetitive effects; (iv) The agencies should decline to adopt a safe harbor for vertical mergers, even if rebuttable, except perhaps when both firms compete in unconcentrated markets; (v) The agencies should consider adopting rebuttable anticompetitive presumptions that a vertical merger harms competition when certain factual predicates are satisfied. We do not intend these presumptions to describe all the ways by which vertical mergers can harm competition, so the agencies should continue to investigate vertical mergers that raise concerns about input and customer foreclosure, loss of a disruptive or maverick firm, evasion of rate regulation or other threats to competition, even if the specific factual predicates of the presumptions are not satisfied

Spin Amplification for Magnetic Sensors Employing Crystal Defects

Recently there have been several theoretical and experimental studies of the prospects for magnetic field sensors based on crystal defects, especially nitrogen vacancy (NV) centres in diamond. Such systems could potentially be incorporated into an AFM-like apparatus in order to map the magnetic properties of a surface at the single spin level. In this Letter we propose an augmented sensor consisting of an NV centre for readout and an `amplifier' spin system that directly senses the local magnetic field. Our calculations show that this hybrid structure has the potential to detect magnetic moments with a sensitivity and spatial resolution far beyond that of a simple NV centre, and indeed this may be the physical limit for sensors of this class

Interactions Between the Effects of Nitrogen, and Phosphorus, Potassium and Sulphur on Grass Production

The interactions between rates of nitrogen (N) and rates of phosphorus (P), potassium (K) or sulphur (S) on yield of ryegrass dominant swards were measured with no return of mown clippings in Southland, New Zealand. In the second year of the trial, the yield response to 176 kg N ha-1 compared with no N increased only slightly with increasing soil Olsen P from 8 to 91 µg g-1 soil. At 352 and 704 kg N ha-1 there was a large increase in the yield response (from 5 to 9.4 and 11 t DM ha-1 respectively) up to an Olsen P of 55 µg g-1 soil. At 176 kg N ha-1, there was a linear yield response (from 3.5 to 6.5 t DM ha-1) as ammonium acetate extracted soil K increased from 80 to 120 µg g-1 soil. A larger yield response to K (from 3.5 to 13.5 t DM ha-1) was measured up to but not above 240 µg K g-1 soil at 352 and 704 kg N ha-1. The yield response to 352 and 704 kg N ha-1 increased with soil S status (from 8.2 to 11.8 t DM ha-1) up to 15 µg calcium phosphate extractable S g-1 soil. These results demonstrated that yield responses to increasing rates of N do not increase above a threshold level of other soil nutrients

Abelian link invariants and homology

We consider the link invariants defined by the quantum Chern-Simons field theory with compact gauge group U(1) in a closed oriented 3-manifold M. The relation of the abelian link invariants with the homology group of the complement of the links is discussed. We prove that, when M is a homology sphere or when a link -in a generic manifold M- is homologically trivial, the associated observables coincide with the observables of the sphere S^3. Finally we show that the U(1) Reshetikhin-Turaev surgery invariant of the manifold M is not a function of the homology group only, nor a function of the homotopy type of M alone.Comment: 18 pages, 3 figures; to be published in Journal of Mathematical Physic

A Silicon Surface Code Architecture Resilient Against Leakage Errors

Spin qubits in silicon quantum dots are one of the most promising building blocks for large scale quantum computers thanks to their high qubit density and compatibility with the existing semiconductor technologies. High fidelity single-qubit gates exceeding the threshold of error correction codes like the surface code have been demonstrated, while two-qubit gates have reached 98\% fidelity and are improving rapidly. However, there are other types of error --- such as charge leakage and propagation --- that may occur in quantum dot arrays and which cannot be corrected by quantum error correction codes, making them potentially damaging even when their probability is small. We propose a surface code architecture for silicon quantum dot spin qubits that is robust against leakage errors by incorporating multi-electron mediator dots. Charge leakage in the qubit dots is transferred to the mediator dots via charge relaxation processes and then removed using charge reservoirs attached to the mediators. A stabiliser-check cycle, optimised for our hardware, then removes the correlations between the residual physical errors. Through simulations we obtain the surface code threshold for the charge leakage errors and show that in our architecture the damage due to charge leakage errors is reduced to a similar level to that of the usual depolarising gate noise. Spin leakage errors in our architecture are constrained to only ancilla qubits and can be removed during quantum error correction via reinitialisations of ancillae, which ensure the robustness of our architecture against spin leakage as well. Our use of an elongated mediator dots creates spaces throughout the quantum dot array for charge reservoirs, measuring devices and control gates, providing the scalability in the design

Ensemble based quantum metrology

The field of quantum metrology promises measurement devices that are fundamentally superior to conventional technologies. Specifically, when quantum entanglement is harnessed the precision achieved is supposed to scale more favourably with the resources employed, such as system size and the time required. Here we consider measurement of magnetic field strength using an ensemble of spins, and we identify a third essential resource: the initial system polarisation, i.e. the low entropy of the original state. We find that performance depends crucially on the form of decoherence present; for a plausible dephasing model, we describe a quantum strategy which can indeed beat the standard quantum limit