Betti number signatures of homogeneous Poisson point processes

The Betti numbers are fundamental topological quantities that describe the k-dimensional connectivity of an object: B_0 is the number of connected components and B_k effectively counts the number of k-dimensional holes. Although they are appealing natural descriptors of shape, the higher-order Betti numbers are more difficult to compute than other measures and so have not previously been studied per se in the context of stochastic geometry or statistical physics. As a mathematically tractable model, we consider the expected Betti numbers per unit volume of Poisson-centred spheres with radius alpha. We present results from simulations and derive analytic expressions for the low intensity, small radius limits of Betti numbers in one, two, and three dimensions. The algorithms and analysis depend on alpha-shapes, a construction from computational geometry that deserves to be more widely known in the physics community.Comment: Submitted to PRE. 11 pages, 10 figure

Aerodynamic characteristics at Mach numbers of 1.5, 1.8, and 2.0 of a blended wing-body configuration with and without integral canards

An exploratory, experimental, and theoretical investigation was made of a cambered, twisted, and blended wing-body concept with and without integral canard surfaces. Theoretical calculations of the static longitudinal and lateral aerodynamic characteristics of the wing-body configurations were compared with the characteristics obtained from tests of a model in the Langley Unitary Plan wind tunnel. Mach numbers of 1.5, 1.8, and 2.0 and a Reynolds number per meter of 6.56 million were used in the calculations and tests. Overall results suggest that planform selection is extremely important and that the supplemental application of new calculation techniques should provide a process for the design of supersonic wings in which spanwise distribution of upwash and leading-edge thrust might be rationally controlled and exploited

Remote Detection of Saline Intrusion in a Coastal Aquifer Using Borehole Measurements of Self-Potential

Funded by NERC CASE studentship . Grant Number: NE/I018417/1Peer reviewedPublisher PD

Tactile Interactions with a Humanoid Robot : Novel Play Scenario Implementations with Children with Autism

Acknowledgments: This work has been partially supported by the European Commission under contract number FP7-231500-ROBOSKIN. Open Access: This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.The work presented in this paper was part of our investigation in the ROBOSKIN project. The project has developed new robot capabilities based on the tactile feedback provided by novel robotic skin, with the aim to provide cognitive mechanisms to improve human-robot interaction capabilities. This article presents two novel tactile play scenarios developed for robot-assisted play for children with autism. The play scenarios were developed against specific educational and therapeutic objectives that were discussed with teachers and therapists. These objectives were classified with reference to the ICF-CY, the International Classification of Functioning – version for Children and Youth. The article presents a detailed description of the play scenarios, and case study examples of their implementation in HRI studies with children with autism and the humanoid robot KASPAR.Peer reviewedFinal Published versio

Suicide-related discussions with depressed primary care patients in the USA: gender and quality gaps. A mixed methods analysis

Objective: To characterise suicide-risk discussions in depressed primary-care patients. Design: Secondary analysis of recordings and self reports by physicians and patients. Descriptive statistics of depression and suicide-related discussion, with qualitative extraction of disclosure, enquiry and physician response. Setting: 12 primary-care clinics between July 2003 and March 2005. Participants: 48 primary-care physicians and 1776 adult patients. Measures: Presence of depression or suicide-related discussions during the encounter; patient and physician demographics; depression symptom severity and suicide ideation as measured by the Patient Health Questionnaire (PHQ9); physician’s decision-making style as measured by the Medical Outcomes Study Participatory Decision-Making Scale; support for autonomy as measured by the Health Care Climate Questionnaire; trust in their physician as measured by the Primary Care Assessment Survey; physician response to suicide-related enquiry or disclosure. Results: Of the 1776 encounters, 128 involved patients scoring \u3e14 on the PHQ9. These patients were seen by 43 of the 48 physicians. Suicide ideation was endorsed by 59% (n1⁄475). Depression was discussed in 52% of the encounters (n1⁄466). Suicide-related discussion occurred in only 11% (n1⁄413) of encounters. 92% (n1⁄412) of the suicide discussions occurred with patients scoring \u3c2 on PHQ9 item 9. Suicide was discussed in only one encounter with a male. Variation in elicitation and response styles demonstrated preferred and discouraged interviewing strategies. Conclusions: Suicide ideation is present in a significant proportion of depressed primary care patients but rarely discussed. Men, who carry the highest risk for suicide, are unlikely to disclose their ideation or be asked about it. Patient-centred communication and positive healthcare climate do not appear to increase the likelihood of suicide related discussion. Physicians should be encouraged to ask about suicide ideation in their depressed patients and, when disclosure occurs, facilitate discussion and develop targeted treatment plans

11 W narrow linewidth laser source at 780nm for laser cooling and manipulation of Rubidium

We present a narrow linewidth continuous laser source with over 11 Watts of output power at 780nm, based on single-pass frequency doubling of an amplified 1560nm fibre laser with 36% efficiency. This source offers a combination of high power, simplicity, mode quality and stability. Without any active stabilization, the linewidth is measured to be below 10kHz. The fibre seed is tunable over 60GHz, which allows access to the D2 transitions in 87Rb and 85Rb, providing a viable high-power source for laser cooling as well as for large-momentum-transfer beamsplitters in atom interferometry. Sources of this type will pave the way for a new generation of high flux, high duty-cycle degenerate quantum gas experiments.Comment: 5 pages, 3 figure

Classical noise and flux: the limits of multi-state atom lasers

By direct comparison between experiment and theory, we show how the classical noise on a multi-state atom laser beam increases with increasing flux. The trade off between classical noise and flux is an important consideration in precision interferometric measurement. We use periodic 10 microsecond radio-frequency pulses to couple atoms out of an F=2 87Rb Bose-Einstein condensate. The resulting atom laser beam has suprising structure which is explained using three dimensional simulations of the five state Gross-Pitaevskii equations.Comment: 4 pages, 3 figure