The Spoor Law: An Anachronism or Constitutional Misfit?

The spoor law is a rule of African customary law that determines liability for stock theft. It provides that, if the tracks of lost or stolen livestock can be traced to a homestead or its immediate surrounds, the head of that establishment will be held liable. If the direction of the spoor do not point to a specific homestead, all those in the vicinity become jointly liable. As a convenient deterrent to the theft of livestock, the spoor law was incorporated into the laws of the Cape Province, Natal and the Transkeian Territories at the end of the nineteenth century, making it the only rule of customary law to be applicable without regard to race prior to the new Constitution. This article questions whether the spoor law still is, and should be, part of South African law. It has never been formally repealed, and still survives in the 1983 Transkei Penal Code. Although the law has not been mentioned in a reported case for many years, it might play a valuable role in crime control, since stock theft remains a serious and pervasive crime in South Africa. The article argues, however, that it will probably not survive constitutional review, because it has the effect of imposing a reverse onus of proof

Ponderomotive entanglement purification

It is shown that ponderomotive force can be used to purify entangled states. The protocol is based on the possibility to exploit such force for a local quantum nondemolition measurement of the total excitation number of continuos variable entangled pairs.Comment: 7 pages, 3 figures, ReVTeX, Accepted for publication in Phys. Lett.

Quantum teleportation over the Swisscom telecommunication network

We present a quantum teleportation experiment in the quantum relay configuration using the installed telecommunication network of Swisscom. In this experiment, the Bell state measurement occurs well after the entanglement has been distributed, at a point where the photon upon which data is teleported is already far away, and the entangled qubits are photons created from a different crystal and laser pulse than the teleported qubit. A raw fidelity of 0.93+/-0.04 has been achieved using a heralded single-photon source.Comment: 6 pages, 7 figures, updated references on May 3rd. To be published in Journal of the Optical Society of America B, Feature issue "Optical Quantum-Information Science", February 200

A Hundred Years from Now

A hundred years from now, dear,We shall not care at all;It will not matter then, a whit,The honey or the gall.The summer days, that we have known,Will all forgotten be, and flown,Where now the roses fall,Where now the roses fall.A hundred years from now, dear,We shall not mind the pain;The throbbing, crimson tide of lifeWill not have left a stain.The song we sand together, dear,Will mean no more, than means a tearAmid a summer rain.A hundred years from now, dearWe\u27ll neither know nor care,What \u27came of all life\u27s bitterness,Or fellowed leve\u27s despair.Then fill the glasses up again, And kiss me thro\u27 the rose-leaf rain;We\u27ll build one castle more, in Spain, And dream, one more dream ther

Enhanced Autocompensating Quantum Cryptography System

We have improved the hardware and software of our autocompensating system for quantum key distribution by replacing bulk optical components at the end stations with fiber-optic equivalents and implementing software that synchronizes end-station activities, communicates basis choices, corrects errors and performs privacy amplification over a local area network. The all fiber-optic arrangement provides stable, efficient and high-contrast routing of the photons. The low bit error rate leads to high error correction efficiency and minimizes data sacrifice during privacy amplification. Characterization measurements made on a number of commercial avalanche photodiodes are presented that highlight the need for improved devices tailored specifically for quantum information applications. A scheme for frequency shifting the photons returning from Alice's station to allow them to be distinguished from backscattered noise photons is also described. OCIS codes: 030.5260, 060.0060, 060.2360, 230.2240, 270.5570.Comment: 13 pages, 1 table, 9 figures; Applied Optics LP (in press, to appear 3/02

Developing hands-on ergonomics lessons for youth

By the time students are ready to enter the workforce they have been exposed to up to 20 years of ergonomics risk factors. As technology evolves, it provides more opportunities for intensive repetitive motion and with computers, cell phones, personal digital assistants (PDAs), and electronic games. The average student engages in fewer active physical activities, sit stationary in mismatched furniture in schools for hours and carry heavy backpacks. While long-term effects remain to be identified, increasingly ergonomists and others concerned with musculoskeletal health and wellness, see a need for early ergonomics education. This interactive session provides a hands-on approach to introducing ergonomics to students. Although different approaches may effectively introduce ergonomics at even early stages of development, this program was designed for youth at the middle to high school age. Attendees will participate in four activities designed to introduce ergonomics at an experiential level. The modules focus on grip strength, effective breathing, optimizing your chair, and backpack safety. The workshop will include presentation and worksheets designed for use by teachers with minimal ergonomics training. Feedback from the participants will be sought for further refining the usability and safety of the training package

Hands-on lessons in ergonomics for youth

Ergonomics risk factors apply to everybody. Numerous adults have experienced disabling injuries related to use of computers and other forms of technology. Now children are using technology even more than adults. Increasingly ergonomics risk factors are being recognized as present in the world of children. Outreach to schools and the surrounding community by employers may help protect the future work force. A growing body of researchers believe that children can benefit from the early introduction of ergonomics awareness and preventative measures. While individual representatives of the educational system may embrace the concept of introducing ergonomics into the classroom, a number of barriers can prevent implementation of integrated programs. Some of the barriers to introducing ergonomics in schools have been absence of a tie to educational standards, the existing demands on teaching hours, and the absence of easily executable lesson plans. Ergonomics is rarely included in teacher training and professional ergonomics expertise is needed for the development of a class-based program. As part of Strategic Vision plan for 2025, a National Laboratory identified community outreach and the future workforces as key areas for initiatives. A series of hands-on interactive modules have been developed by professional ergonomics specialists. They are being tested with elementary, middle and high school students. Where possible, the content has been tied to the educational standards in the State of California in the USA. Currently the modules include grip strength, effective breathing, optimal keyboard and mouse positions, optimizing chairs, posture and movement, backpack safety and safe lifting. Each module takes the students through a related activity or experience. An individual worksheet asks them questions about the experience and guides them to consider implications in their activities of daily living. A module on hearing is under development. The goal is to have a toolkit that teachers can use in classrooms with minimal training. The kit will come with lesson plans, including background material, key points, questions and answers, possible homework assignments and references. It will include instructions and worksheets for students as well as the materials needed for each module. A pre- and posttest will be administered to test the awareness and understanding of the principles introduced in through the modules. This interactive session will offer the opportunity to for attendees to participate in some of the modules that have been developed to provide experiential demonstration of ergonomics principles. Attendees will experience ergonomics in action and be able to evaluate the applicability of the process in their own area in the world of ergonomics. The session will consist of 20 minutes introduction, 40 minutes working with the toolkit, finally another 30 minutes for questions or discussion for a total time of 90 minutes

Statistical Inference, Distinguishability of Quantum States, And Quantum Entanglement

We argue from the point of view of statistical inference that the quantum relative entropy is a good measure for distinguishing between two quantum states (or two classes of quantum states) described by density matrices. We extend this notion to describe the amount of entanglement between two quantum systems from a statistical point of view. Our measure is independent of the number of entangled systems and their dimensionality.Comment: 11 pages no figures, to appear in Phys. Rev.

Photonic entanglement as a resource in quantum computation and quantum communication

Entanglement is an essential resource in current experimental implementations for quantum information processing. We review a class of experiments exploiting photonic entanglement, ranging from one-way quantum computing over quantum communication complexity to long-distance quantum communication. We then propose a set of feasible experiments that will underline the advantages of photonic entanglement for quantum information processing.Comment: 33 pages, 4 figures, OSA styl

Practical free-space quantum key distribution over 1 km

A working free-space quantum key distribution (QKD) system has been developed and tested over an outdoor optical path of ~1 km at Los Alamos National Laboratory under nighttime conditions. Results show that QKD can provide secure real-time key distribution between parties who have a need to communicate secretly. Finally, we examine the feasibility of surface to satellite QKD.Comment: 5 pages, 2 figures, 2 tables. Submitted to Physics Review Letters, May 199