Plasma panel‐based radiation detectors

The plasma panel sensor (PPS) is a gaseous micropattern radiation detector under current development. It has many operational and fabrication principles common to plasma display panels. It comprises a dense matrix of small, gas plasma discharge cells within a hermetically sealed panel. As in plasma display panels, it uses nonreactive, intrinsically radiation‐hard materials such as glass substrates, refractory metal electrodes, and mostly inert gas mixtures. We are developing these devices primarily as thin, low‐mass detectors with gas gaps from a few hundred microns to a few millimeters. The PPS is a high gain, inherently digital device with the potential for fast response times, fine position resolution (<50‐µm RMS) and low cost. In this paper, we report on prototype PPS experimental results in detecting betas, protons, and cosmic muons, and we extrapolate on the PPS potential for applications including the detection of alphas, heavy ions at low‐to‐medium energy, thermal neutrons, and X‐rays.     

Carbon Copying Onto Dirty Paper

A generalization of the problem of writing on dirty paper is considered in which one transmitter sends a common message to multiple receivers. Each receiver experiences on its link an additive interference (in addition to the additive noise), which is known noncausally to the transmitter but not to any of the receivers. Applications range from wireless multiple-antenna multicasting to robust dirty paper coding. We develop results for memoryless channels in Gaussian and binary special cases. In most cases, we observe that the availability of side information at the transmitter increases capacity relative to systems without such side information, and that the lack of side information at the receivers decreases capacity relative to systems with such side information. For the noiseless binary case, we establish the capacity when there are two receivers. When there are many receivers, we show that the transmitter side information provides a vanishingly small benefit. When the interference is large and independent across the users, we show that time sharing is optimal. For the Gaussian case, we present a coding scheme and establish its optimality in the high signal-to-interference-plus-noise limit when there are two receivers. When the interference power is large and independent across all the receivers, we show that time-sharing is again optimal. Connections to the problem of robust dirty paper coding are also discussed     

Numerical modeling and experimental evaluation of a time domain UWB technique for soil void detection

A growing percentage of waste and storm water conveyance systems are approaching or exceeded their design life, suffering from accelerated deterioration and subsequently increased rates of failure. Discontinuities in the pipe wall may lead to the formation of voids in the soil embedment surrounding it via the transportation of fine soil particles by infiltrating ground water. This paper describes a method that utilizes ultra wideband (UWB) time domain principles to detect the presence and location of soil voids in early stages of formation, thus preventing a catastrophic collapse of the pipe and/or a structure above it (e.g., road surface). A three dimensional numerical model simulating the propagation of UWB pulses within a buried pipeline was developed. The results from the numerical model were validated using experimental measurements performed utilizing a full scale test bed. It is shown that a UWB based sensory system is capable of detecting even minor voids around non-ferrous buried pipes.     

Dynamic optogalvanic effect in rare gases and uranium

We present time resolved observations of the optogalvanic signal from a rare-gas buffered, uranium hollow-cathode tube irradiated by pulsed dye lasers. The design of the measurement circuit is also discussed.     

Time efficient k-shot broadcasting in known topology radio networks

The paper considers broadcasting protocols in radio networks with known topology that are efficient in both time and energy. The radio network is modelled as an undirected graph G = (V, E) where |V| = n. It is assumed that during execution of the communication task every node in V is allowed to transmit at most once. Under this assumption it is shown that any radio broadcast protocol requires transmission rounds, where D is the diameter of G. This lower bound is complemented with an efficient construction of a deterministic protocol that accomplishes broadcasting in rounds. Moreover, if we allow each node to transmit at most k times, the lower bound on the number of transmission rounds holds. We also provide a randomised protocol that accomplishes broadcasting in rounds. The paper concludes with a number of open problems in the area. The research of L. Gąsieniec, D.R. Kowalski and C. Su supported in part by the Royal Society grant Algorithmic and Combinatorial Aspects of Radio Communication, IJP - 2006/R2. The research of E. Kantor and D. Peleg supported in part by grants from the Minerva Foundation and the Israel Ministry of Science.     

Applications of Horizontal Characterization Techniques in Trenchless Construction

Horizontal site characterization technologies present a rapidly evolving alternative to traditional vertical site investigation methods for subsurface investigations of large diameter trenchless construction projects. A state-of-the-art review of horizontal site characterization tools, both currently available and under development, is presented. Additionally, a rational methodology for the selection and deployment of horizontal site investigation techniques in trenchless construction projects is also presented. The methodology enables the user to define and quantify the risks involved in a particular project, as well as to evaluate the degree to which these risks can be mitigated using various site characterization techniques. The proposed model is demonstrated using a working example. The paper concludes with a discussion of future trends in this exciting new field. The main conclusions drawn from this work are (1) adequate subsurface information is invaluable for underground construction; (2) site investigation programs of linear construction projects can be enhanced by horizontal characterization techniques; and (3) the availability of continuous and near-continuous subsurface information enables the utilization of new approaches for the analysis and representation of subsurface data.     

"Selfobject" Needs in Kohut's Self Psychology: Links With Attachment, Self-Cohesion, Affect Regulation, and Adjustment.

Seven studies examined the validity and usefulness of central constructs in Kohut's self psychology: selfobject needs for mirroring, idealization, and twinship and avoidance of acknowledging these needs. These constructs were assessed with a new self-report measure that was found to be reliable, valid, and empirically linked with a variety of constructs in contemporary personality and social psychology. The findings supported and refined Kohut's ideas about the independence of the 3 selfobject needs, the orthogonality between these needs and defensive attempts to avoid acknowledging them, the motivational bases of narcissism, and the contribution of selfobject needs to problems in interpersonal functioning, mental health, self-cohesion, and affect regulation. The findings reveal mutually beneficial conceptual links between Kohut's self psychology and attachment theory and suggest ways in which Kohut's theory can be studied empirically. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Broadcasting in UDG radio networks with unknown topology

The paper considers broadcasting in radio networks, modeled as unit disk graphs (UDG). Such networks occur in wireless communication between sites (e.g., stations or sensors) situated in a terrain. Network stations are represented by points in the Euclidean plane, where a station is connected to all stations at distance at most 1 from it. A message transmitted by a station reaches all its neighbors, but a station hears a message (receives the message correctly) only if exactly one of its neighbors transmits at a given time step. One station of the network, called the source, has a message which has to be disseminated to all other stations. Stations are unaware of the network topology. Two broadcasting models are considered. In the conditional wake up model, the stations other than the source are initially idle and cannot transmit until they hear a message for the first time. In the spontaneous wake up model, all stations are awake (and may transmit messages) from the beginning. It turns out that broadcasting time depends on two parameters of the UDG network, namely, its diameter D and its granularity g, which is the inverse of the minimum distance between any two stations. We present a deterministic broadcasting algorithm which works in time O (D g) under the conditional wake up model and prove that broadcasting in this model cannot be accomplished by any deterministic algorithm in time better than ${\Omega (D \sqrt{g})}The paper considers broadcasting in radio networks, modeled as unit disk graphs (UDG). Such networks occur in wireless communication between sites (e.g., stations or sensors) situated in a terrain. Network stations are represented by points in the Euclidean plane, where a station is connected to all stations at distance at most 1 from it. A message transmitted by a station reaches all its neighbors, but a station hears a message (receives the message correctly) only if exactly one of its neighbors transmits at a given time step. One station of the network, called the source, has a message which has to be disseminated to all other stations. Stations are unaware of the network topology. Two broadcasting models are considered. In the conditional wake up model, the stations other than the source are initially idle and cannot transmit until they hear a message for the first time. In the spontaneous wake up model, all stations are awake (and may transmit messages) from the beginning. It turns out that broadcasting time depends on two parameters of the UDG network, namely, its diameter D and its granularity g, which is the inverse of the minimum distance between any two stations. We present a deterministic broadcasting algorithm which works in time O (D g) under the conditional wake up model and prove that broadcasting in this model cannot be accomplished by any deterministic algorithm in time better than W(D ?g){\Omega (D \sqrt{g})} . For the spontaneous wake up model, we design two deterministic broadcasting algorithms: the first works in time O (D + g ²) and the second in time O (D log g). While neither of these algorithms alone is optimal for all parameter values, we prove that the algorithm obtained by interleaving their steps, and thus working in time O ( min{ D + g², D logg}){ O \left( \min\left\{ D + g^2, D \log{g}\right\}\right) }, turns out to be optimal by establishing a matching lower bound.     

The Light-Wall: tangible user interfaces for learning systems thinking

This paper presents the design of the Light-Wall, a tangible user interface aimed at teaching children the core principles of systems thinking. This document presents the design problem, process and solution.