Comparison of photoexcited p-InAs THz radiation source with conventional thermal radiation sources

P-type InAs excited by ultrashort optical pulses has been shown to be a strong emitter of terahertz radiation. In a direct comparison between a p-InAs emitter and conventional thermal radiationsources, we demonstrate that under typical excitation conditions p-InAs produces more radiation below 1.2 THz than a globar. By treating the globar as a blackbody emitter we calibrate a siliconbolometer which is used to determine the power of the p-InAs emitter. The emitted terahertz power was found to be 98±10 nW in this experiment

On the Geroch-Traschen class of metrics

We compare two approaches to semi-Riemannian metrics of low regularity. The maximally 'reasonable' distributional setting of Geroch and Traschen is shown to be consistently contained in the more general setting of nonlinear distributional geometry in the sense of Colombea

Far Infrared Spectroscopy of CsNiCl₃ Type Crystals

A far infrared interferometer has been interfaced to a microcomputer and programs developed to enable fourier transform spectroscopy to be carried out in real time. A Heᶾ cooled bolometer-superconducting magnet system has been constructed for far infrared Zeeman spectroscopy. The bolometer element is magnetically shielded from the field using superconducting lead. The theory of the transmission of polarized radiation through slabs of non-isotropic dielectric crystals mounted on a dielectric substrate is developed. The resulting equations allow general features of far infrared transmission spectra to be examined. For example they show that for "thicker" crystals, the transverse optical mode absorption lines are asymmetric while the longitudinal optical mode absorption lines are symmetric. For large angles of incidence, an extra absorption line is predicted to occur above the longitudinal optic mode frequency for crystals of low dielectric constant. The infrared-active phonon spectra of thirteen crystals of the CsNiCl₃ type structure are reported and assigned to specific lattice modes. Using polarized, Zeeman spectroscopy, two magnon lines are identified in the quasi 1 dimensional antiferromagnet RbCoBr₃ at 100.0±0.5 cm⁻¹ and 120.0±0.5 cm⁻¹ , each having a g value of 3.8±0.4. These lines are fitted using a perturbed Ising model to give a longitudinal interchain exchange strength of 51 cm⁻¹ and a relative longitudinal interchain exchange value of 0.06 for RbCoBr₃ at 1.7 K. A possible antiresonance line is reported at 114.6 cm⁻¹ for RbCoBr₃ and preliminary work is reported in the search for magnons in other CsNiCl₃ type crystals

Towards practice-based studies of HRM: an actor-network and communities of practice informed approach

HRM may have become co-terminus with the new managerialism in the rhetorical orthodoxies of the HRM textbooks and other platforms for its professional claims. However, we have detailed case-study data showing that HR practices can be much more complicated, nuanced and indeed resistive toward management within organizational settings. Our study is based on ethnographic research, informed by actor-network theory and community of practice theory conducted by one of the authors over an 18-month period. Using actor-network theory in a descriptive and critical way, we analyse practices of managerial resistance, enrolment and counter-enrolment through which an unofficial network of managers used a formal HRM practice to successfully counteract the official strategy of the firm, which was to close parts of a production site. As a consequence, this network of middle managers effectively changed top management strategy and did so through official HRM practices, coupled with other actor-network building processes, arguably for the ultimate benefit of the organization, though against the initial views of the top management. The research reported here, may be characterized as a situated study of HRM-in-practice and we draw conclusions which problematize the concept of HRM in contemporary management literature

Systematic reviews of complementary therapies - an annotated bibliography. Part 1: Acupuncture

Background Complementary therapies are widespread but controversial. We aim to provide a comprehensive collection and a summary of systematic reviews of clinical trials in three major complementary therapies (acupuncture, herbal medicine, homeopathy). This article is dealing with acupuncture. Potentially relevant reviews were searched through the register of the Cochrane Complementary Medicine Field, the Cochrane Library, Medline, and bibliographies of articles and books. To be included articles had to review prospective clinical trials of acupuncture; had to describe review methods explicitly; had to be published; and had to focus on treatment effects. Information on conditions, interventions, methods, results and conclusions was extracted using a pretested form and summarized descriptively. Results From a total of 48 potentially relevant reviews preselected in a screeening process 39 met the inclusion criteria. 22 were on various pain syndromes or rheumatic diseases. Other topics addressed by more than one review were addiction, nausea, asthma and tinnitus. Almost unanimously the reviews state that acupuncture trials include too few patients. Often included trials are heterogeneous regarding patients, interventions and outcome measures, are considered to have insufficient quality and contradictory results. Convincing evidence is available only for postoperative nausea, for which acupuncture appears to be of benefit, and smoking cessation, where acupuncture is no more effective than sham acupuncture. Conclusions A large number of systematic reviews on acupuncture exists. What is most obvious from these reviews is the need for (the funding of) well-designed, larger clinical trials

Mastering physics?

MasteringPhysics is a tutorial software package. The University of Wollongong adopted it for one stream of first-year physics in second session 2004. The goal of the research is to determine the impact MasteringPhysics had on examination results in the subject and on student opinion of the subject

A topos for algebraic quantum theory

The aim of this paper is to relate algebraic quantum mechanics to topos theory, so as to construct new foundations for quantum logic and quantum spaces. Motivated by Bohr's idea that the empirical content of quantum physics is accessible only through classical physics, we show how a C*-algebra of observables A induces a topos T(A) in which the amalgamation of all of its commutative subalgebras comprises a single commutative C*-algebra. According to the constructive Gelfand duality theorem of Banaschewski and Mulvey, the latter has an internal spectrum S(A) in T(A), which in our approach plays the role of a quantum phase space of the system. Thus we associate a locale (which is the topos-theoretical notion of a space and which intrinsically carries the intuitionistic logical structure of a Heyting algebra) to a C*-algebra (which is the noncommutative notion of a space). In this setting, states on A become probability measures (more precisely, valuations) on S(A), and self-adjoint elements of A define continuous functions (more precisely, locale maps) from S(A) to Scott's interval domain. Noting that open subsets of S(A) correspond to propositions about the system, the pairing map that assigns a (generalized) truth value to a state and a proposition assumes an extremely simple categorical form. Formulated in this way, the quantum theory defined by A is essentially turned into a classical theory, internal to the topos T(A).Comment: 52 pages, final version, to appear in Communications in Mathematical Physic