The Role of Tree Clinics in Urban Forestry

A tree clinic analyzes tree problems and recommends appropriate actions to the public. The objective of tree clinics is to inform the citizen about urban trees. This paper is based on the experiences of 30 tree clinics held in Ann Arbor during the last eight years. The ingredients necessary for a successful tree clinic are discussed: (I) active sponsor, (2) suitable date and time, (3) good location, (4) proper publicity, (5) diversified experts, (6) proper organization, (7) sizable public turnout, and (8) follow-up publicity and acknowledgments

ENGAGE A VOICE, REPRESS FATIGUE; THE COINCIDENT EVOLUTION OF HOMININ VOCALIZATION AND A METABOLIC THRESHOLD

Physiologically self-protective mechanisms borne from hominin evolutionary history that increase survivability are not unknown to science. In reviewing exercise science literature regarding testing and assessment measures of subjects talking while exercising, a logical question has materialized: To what degree has evolution facilitated synchronization of comfortable oral communication with sustainable exercise intensity? An individual able to engage a voice, represses fatigue. The Talk Test, is a practical strategy whereby a subject deliberately speaks during an exercise protocol. It is a common tool in both kinesiology and clinical fields because it inherently identifies a pivotal metabolic threshold. The coincidence of comfortable ability to talk and perform sustainable sub-threshold exercise intensity, also affords complete physiological recovery within one solar day. A sustained, increased vigor above this stage, though possible, requires more than 24 hours of metabolic recovery, and muscular and range of motion restoration due to overuse may require at least 96 hours

Remote capacitive sensing in two-dimension quantum-dot arrays

We investigate gate-defined quantum dots in silicon on insulator nanowire field-effect transistors fabricated using a foundry-compatible fully-depleted silicon-on-insulator (FD-SOI) process. A series of split gates wrapped over the silicon nanowire naturally produces a $2\times n$ bilinear array of quantum dots along a single nanowire. We begin by studying the capacitive coupling of quantum dots within such a 2$\times$2 array, and then show how such couplings can be extended across two parallel silicon nanowires coupled together by shared, electrically isolated, 'floating' electrodes. With one quantum dot operating as a single-electron-box sensor, the floating gate serves to enhance the charge sensitivity range, enabling it to detect charge state transitions in a separate silicon nanowire. By comparing measurements from multiple devices we illustrate the impact of the floating gate by quantifying both the charge sensitivity decay as a function of dot-sensor separation and configuration within the dual-nanowire structure.Comment: 9 pages, 3 figures, 35 cites and supplementar

Dynamic analysis of a lithium-boiling potassium refractory metal Rankine cycle power system for the Jet Propulsion Laboratory

Lithium-boiling potassium refractory metal Rankine cycle power system heat transfer model

Bliss v. Attorney General of Canada: From Legal Defeat to Political Victory

This article rests on the distinction between the legal and political meanings of a judicial decision. Cases that are resolved in legal terms may have unpredictable political consequences. Bliss v. Attorney General of Canada (1978) demonstrates this brilliantly: Stella Bliss\u27s argument that Canadian Unemployment Insurance maternity benefits violated the equality provisions of the Bill of Rights was soundly defeated in the court& Ultimately, however, a loose coalition of feminist and civil liberties groups took Bliss into the political process and succeeded in forcing a revision of Unemployment Insurance along with a dramatic expansion of the scope of section 15 of the Canadian Charter of Rights and Freedoms. The article traces the complex transition from personal case to political cause, demonstrating that Supreme Court decisions have a specious finality: disputes may only be conclusively resolved by a broader political process wherein organizational strength, not legal principle, prevails

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

Coherence of Spin Qubits in Silicon

Given the effectiveness of semiconductor devices for classical computation one is naturally led to consider semiconductor systems for solid state quantum information processing. Semiconductors are particularly suitable where local control of electric fields and charge transport are required. Conventional semiconductor electronics is built upon these capabilities and has demonstrated scaling to large complicated arrays of interconnected devices. However, the requirements for a quantum computer are very different from those for classical computation, and it is not immediately obvious how best to build one in a semiconductor. One possible approach is to use spins as qubits: of nuclei, of electrons, or both in combination. Long qubit coherence times are a prerequisite for quantum computing, and in this paper we will discuss measurements of spin coherence in silicon. The results are encouraging - both electrons bound to donors and the donor nuclei exhibit low decoherence under the right circumstances. Doped silicon thus appears to pass the first test on the road to a quantum computer.Comment: Submitted to J Cond Matter on Nov 15th, 200

Quantum computing with an electron spin ensemble

We propose to encode a register of quantum bits in different collective electron spin wave excitations in a solid medium. Coupling to spins is enabled by locating them in the vicinity of a superconducting transmission line cavity, and making use of their strong collective coupling to the quantized radiation field. The transformation between different spin waves is achieved by applying gradient magnetic fields across the sample, while a Cooper Pair Box, resonant with the cavity field, may be used to carry out one- and two-qubit gate operations.Comment: Several small corrections and modifications. This version is identical to the version published in Phys. Rev. Let

Global Optical Control of a Quantum Spin Chain

Quantum processors which combine the long decoherence times of spin qubits together with fast optical manipulation of excitons have recently been the subject of several proposals. I show here that arbitrary single- and entangling two-qubit gates can be performed in a chain of perpetually coupled spin qubits solely by using laser pulses to excite higher lying states. It is also demonstrated that universal quantum computing is possible even if these pulses are applied {\it globally} to a chain; by employing a repeating pattern of four distinct qubit units the need for individual qubit addressing is removed. Some current experimental qubit systems would lend themselves to implementing this idea.Comment: 5 pages, 3 figure