Quantum criticality in a double quantum-dot system

We discuss the realization of the quantum-critical non-Fermi liquid state, originally discovered within the two-impurity Kondo model, in double quantum-dot systems. Contrary to the common belief, the corresponding fixed point is robust against particle-hole and various other asymmetries, and is only unstable to charge transfer between the two dots. We propose an experimental set-up where such charge transfer processes are suppressed, allowing a controlled approach to the quantum critical state. We also discuss transport and scaling properties in the vicinity of the critical point.Comment: 4 pages, 3 figs; (v2) final version as publishe

Near-infrared imaging of demineralization on the occlusal surfaces of teeth without the interference of stains.

Most new caries lesions are found in the pits and fissures of the occlusal surface. Radiographs have extremely low sensitivity for early occlusal decay, and by the time the lesion is severe enough to appear on a radiograph, it typically has penetrated well into the dentin and surgical intervention is required. The occlusal surfaces are often heavily stained, and visual and tactile detection have poor sensitivity and specificity. Previous near-infrared imaging studies at wavelengths beyond 1300 nm have demonstrated that stains are not visible and demineralization on the occlusal surfaces can be viewed without interference from stains. The objective of our study is to determine how the contrast between sound and lesion areas on occlusal surfaces varies with wavelength from the visible to 2350 nm and determine to what degree stains interfere with that contrast. The lesion contrast for reflectance is measured in 55 extracted teeth with suspected occlusal lesions from 400 to 2350 nm employing silicon and indium gallium arsenide imaging arrays. In addition, the lesion contrast is measured on 25 extracted teeth with suspected occlusal lesions from 400 to 1600 nm in reflectance and from 830 to 1400 nm in transillumination before and after stains are removed using a ultrasonic scaler. The highest lesion contrast in reflectance is measured at wavelengths >1700  nm. Stains interfere significantly at wavelengths <1150  nm (400 to 1150) for both reflectance and transillumination measurements. Our study suggests that the optimum wavelengths for imaging decay in the occlusal surfaces are >1700  nm for reflectance (1700 to 2350 nm) and near 1300 nm (1250 to 1350 nm) for transillumination

Securing Internet of Things with Lightweight IPsec

Real-world deployments of wireless sensor networks (WSNs) require secure communication. It is important that a receiver is able to verify that sensor data was generated by trusted nodes. In some cases it may also be necessary to encrypt sensor data in transit. Recently, WSNs and traditional IP networks are more tightly integrated using IPv6 and 6LoWPAN. Available IPv6 protocol stacks can use IPsec to secure data exchange. Thus, it is desirable to extend 6LoWPAN such that IPsec communication with IPv6 nodes is possible. It is beneficial to use IPsec because the existing end-points on the Internet do not need to be modified to communicate securely with the WSN. Moreover, using IPsec, true end-to-end security is implemented and the need for a trustworthy gateway is removed. In this paper we provide End-to-End (E2E) secure communication between an IP enabled sensor nodes and a device on traditional Internet. This is the first compressed lightweight design, implementation, and evaluation of 6LoWPAN extension for IPsec on Contiki. Our extension supports both IPsec's Authentication Header (AH) and Encapsulation Security Payload (ESP). Thus, communication endpoints are able to authenticate, encrypt and check the integrity of messages using standardized and established IPv6 mechanisms

A study of the interactions of 200 A GeV 16O and 32S ions in nuclear emulsion

The general features of the hadronic inelastic interactions of 200 A GeV 16O and 32S ions with emulsion nuclei have been compared and contrasted. The fragmentation of 16O and 32S ions into projectile fragments of Z ≥ 2 has been investigated. The multiplicity distribution of slow, target associated particles and fast, shower particles and the correlations among various multiplicity parameters have been studied for varying degrees of projectile fragmentation. The results are consistent with a geometrical model. Rapidity analysis of a particular class of events, which exhibit complete projectile break-up without overt sign of low-energy target fragmentation, has been carried out. A systematic study of the electromagnetic dissociation(EMD) of 16O and 32S ions projectiles into exclusive channels of charged fragments at an incident energy of 200 A GeV has been carried out. The photoproduction cross-sections on 16O and 32S ions were determined by estimating the energy released in each interaction and assuming a model for the intensity and energy spectrum of the virtual photons. While there was good agreement for both 16O and 32S ions results for (γ, ρ) processes when compared with real photons data, especially in the giant dipole region, the rates for the (γ, α) processes were found to be an order of magnitude larger than expected. However, events, which have all the features ascribed to electromagnetic breakup plus a low-energy recoil proton, have been identified in interactions of 16O. An eikonal distorted-wave impulse approximation(DWIA) estimate of the target A-dependence of strong interaction diffractive dissociation, based on the hydrogen data, suggests that most of the (C α) final states might in fact be of hadronic origin. The mean free paths of fragments(Z=2-7) from the interaction of 16O at 200 A GeV at different distances from their production point have been investigated and were found to be the same, independent of their multiplicity, target size, production generation and production mechanism

Model Dependence of the Properties of S11 Baryon Resonances

The properties of baryon resonances are extracted from a complicated process of fitting sophisticated, empirical models to data. The reliability of this process comes from the quality of data and the robustness of the models employed. With the large of amount of data coming from recent experiments, this is an excellent time for a study of the model dependence of this extraction process. A test case is chosen where many theoretical details of the model are required, the S11 partial wave. The properties of the two lowest N* resonances in this partial wave are determined using various models of the resonant and non-resonant amplitudes.Comment: 24 pages, 10 figures; revised fits with error estimates, expanded comparison between CMB and K-matrix model

Computing Thresholds of Linguistic Saliency

PACLIC 21 / Seoul National University, Seoul, Korea / November 1-3, 200

Continuous integral kernels for unbounded Schroedinger semigroups and their spectral projections

By suitably extending a Feynman-Kac formula of Simon [Canadian Math. Soc. Conf. Proc, 28 (2000), 317-321], we study one-parameter semigroups generated by (the negative of) rather general Schroedinger operators, which may be unbounded from below and include a magnetic vector potential. In particular, a common domain of essential self-adjointness for such a semigroup is specified. Moreover, each member of the semigroup is proven to be a maximal Carleman operator with a continuous integral kernel given by a Brownian-bridge expectation. The results are used to show that the spectral projections of the generating Schroedinger operator also act as Carleman operators with continuous integral kernels. Applications to Schroedinger operators with rather general random scalar potentials include a rigorous justification of an integral-kernel representation of their integrated density of states - a relation frequently used in the physics literature on disordered solids.Comment: 41 pages. Final version. Dedicated to Volker Enss on the occasion of his 60th birthda