A geometry of information, I: Nerves, posets and differential forms

The main theme of this workshop (Dagstuhl seminar 04351) is `Spatial Representation: Continuous vs. Discrete'. Spatial representation has two contrasting but interacting aspects (i) representation of spaces' and (ii) representation by spaces. In this paper, we will examine two aspects that are common to both interpretations of the theme, namely nerve constructions and refinement. Representations change, data changes, spaces change. We will examine the possibility of a `differential geometry' of spatial representations of both types, and in the sequel give an algebra of differential forms that has the potential to handle the dynamical aspect of such a geometry. We will discuss briefly a conjectured class of spaces, generalising the Cantor set which would seem ideal as a test-bed for the set of tools we are developing.Comment: 28 pages. A version of this paper appears also on the Dagstuhl seminar portal http://drops.dagstuhl.de/portals/04351

The impact of vaporized nanoemulsions on ultrasound-mediated ablation

BACKGROUND: The clinical feasibility of using high-intensity focused ultrasound (HIFU) for ablation of solid tumors is limited by the high acoustic pressures and long treatment times required. The presence of microbubbles during sonication can increase the absorption of acoustic energy and accelerate heating. However, formation of microbubbles within the tumor tissue remains a challenge. Phase-shift nanoemulsions (PSNE) have been developed as a means for producing microbubbles within tumors. PSNE are emulsions of submicron-sized, lipid-coated, and liquid perfluorocarbon droplets that can be vaporized into microbubbles using short (5 MPa) acoustic pulses. In this study, the impact of vaporized phase-shift nanoemulsions on the time and acoustic power required for HIFU-mediated thermal lesion formation was investigated in vitro. METHODS: PSNE containing dodecafluoropentane were produced with narrow size distributions and mean diameters below 200 nm using a combination of sonication and extrusion. PSNE was dispersed in albumin-containing polyacrylamide gel phantoms for experimental tests. Albumin denatures and becomes opaque at temperatures above 58°C, enabling visual detection of lesions formed from denatured albumin. PSNE were vaporized using a 30-cycle, 3.2-MHz, at an acoustic power of 6.4 W (free-field intensity of 4,586 W/cm(2)) pulse from a single-element, focused high-power transducer. The vaporization pulse was immediately followed by a 15-s continuous wave, 3.2-MHz signal to induce ultrasound-mediated heating. Control experiments were conducted using an identical procedure without the vaporization pulse. Lesion formation was detected by acquiring video frames during sonication and post-processing the images for analysis. Broadband emissions from inertial cavitation (IC) were passively detected with a focused, 2-MHz transducer. Temperature measurements were acquired using a needle thermocouple. RESULTS: Bubbles formed at the HIFU focus via PSNE vaporization enhanced HIFU-mediated heating. Broadband emissions detected during HIFU exposure coincided in time with measured accelerated heating, which suggested that IC played an important role in bubble-enhanced heating. In the presence of bubbles, the acoustic power required for the formation of a 9-mm(3) lesion was reduced by 72% and the exposure time required for the onset of albumin denaturation was significantly reduced (by 4 s), provided that the PSNE volume fraction in the polyacrylamide gel was at least 0.008%. CONCLUSIONS: The time or acoustic power required for lesion formation in gel phantoms was dramatically reduced by vaporizing PSNE into bubbles. These results suggest that PSNE may improve the efficiency of HIFU-mediated thermal ablation of solid tumors; thus, further investigation is warranted to determine whether bubble-enhanced HIFU may potentially become a viable option for cancer therapy.R21 EB009493 - NIBIB NIH HH

The detection and tracking of portable GSM handset using a 5-element circular array

Includes bibliographical references (leaves 130-131)Direction Finding (OF) is a process that involves estimating the directions of the arrival for propagating wavefronts impinging on an antenna array from arbitrary directions relative to that antenna array. By understanding how the signals captured relate to the geometry of the OF antenna, one can separate out these signals spatially, and provide their directions of arrival with some degree of certainty. GSM, the Global System for Mobile Communications is a mobile digital communications system which has rapidly gained acceptance on a global scale since the early 1990s. Because the communications standard is made use of throughout the world today, it would be desirable to investigate the feasibility of the detection and tracking of such signals as an extension for OF platforms that are used by monitoring authorities such as the police or service providers. This thesis presents and discusses the implications of detecting and tracking GSM mobile handsets. Because the thesis was commissioned by a company that already manufactures broadband surveillance equipment with a particular OF implementation, the thesis approaches the problem with their specific implementation in mind assessing its competency in detecting and tracking GSM mobile phones. To understand the nature of GSM, a simulator was developed to convey information about the structure of the datasets that would be recorded in the field, and is compared to datasets captured with the OF equipment. Conclusions are drawn from the recordings, and recommendations for future work in this field are discussed

Marlowe\u27s curious queens: a gender study

Christopher Marlowe\u27s plays reflect the changing concepts of gender found within the time he wrote them, as Elizabethan England struggled with the contradictions between the ancient, rigid gender roles embodied in the Petrarchan model and the paradox of a female monarch who rejected all suitors. This struggle, coupled with the rising popularity of the companionate marriage that itself implied some degree of sexual equality, challenged fundamental patriarchal assumptions about gender, property, even government, and critical thinkers like Marlowe infused their works with ideas from the debates of the day. Marlowe\u27s early plays, especially Tamburlaine I & II, reflect a masculocentric world-view that treasures and eroticizes male relationships while marginalizing, if not ignoring altogether, male-female relations and female status in general. Edward II and the anomalous Dido, Queen of Carthage, however, are the products of a mind struggling with questions of gender, from the cunning of Isabella in the former to the queen who dominates Aeneas and threatens the order of heaven itself in the latter. Indeed, I contend that Dido ranks as one the most revolutionary characters in Renaissance drama, one who not only challenges but overturns gender roles, dominating the males in her world with as much power as Tamburlaine wields in his. Marlowe creates something in Isabella and especially Dido that history has no context for, that Aristotle and most Renaissance dramatists alike would dismiss as improbable, if not impossible: the tragic heroin

Use of the MultiNest algorithm for gravitational wave data analysis

We describe an application of the MultiNest algorithm to gravitational wave data analysis. MultiNest is a multimodal nested sampling algorithm designed to efficiently evaluate the Bayesian evidence and return posterior probability densities for likelihood surfaces containing multiple secondary modes. The algorithm employs a set of live points which are updated by partitioning the set into multiple overlapping ellipsoids and sampling uniformly from within them. This set of live points climbs up the likelihood surface through nested iso-likelihood contours and the evidence and posterior distributions can be recovered from the point set evolution. The algorithm is model-independent in the sense that the specific problem being tackled enters only through the likelihood computation, and does not change how the live point set is updated. In this paper, we consider the use of the algorithm for gravitational wave data analysis by searching a simulated LISA data set containing two non-spinning supermassive black hole binary signals. The algorithm is able to rapidly identify all the modes of the solution and recover the true parameters of the sources to high precision.Comment: 18 pages, 4 figures, submitted to Class. Quantum Grav; v2 includes various changes in light of referee's comment

A geometry of information, II: Sorkin models, and biextensional collapses

In this second part of our contribution to the workshop, we look in more detail at the Sorkin model, its relationship to constructions in Chu space theory, and then compare it with the Nerve constructions given in the first part

Improved Fluorescent In Situ Hybridization Method for Detection of Bacteria from Activated Sludge and River Water by Using DNA Molecular Beacons and Flow Cytometry �

Fluorescent in situ hybridization (FISH) remains a key technique in microbial ecology. Molecular beacons (MBs) are self-reporting probes that have potential advantages over linear probes for FISH. MB-FISH strategies have been described using both DNA-based and peptide nucleic acid (PNA)-based approaches. Although recent reports have suggested that PNA MBs are superior, DNA MBs have some advantages, most notably cost. The data presented here demonstrate that DNA MBs are suitable for at least some FISH applications in complex samples, providing superior discriminatory power compared to that of corresponding linear DNA-FISH probes. The use of DNA MBs for flow cytometric detection of Pseudomonas putida resulted in approximately double the signal-to-noise ratio of standard linear DNA probes when using laboratory-grown cultures and yielded improved discrimination of target cells in spiked environmental samples, without a need for separate washing steps. DNA MBs were also effective for the detection and cell sorting of both spiked and indigenous P. putida from activated sludge and river water samples. The use of DNA MB-FISH presents another increase in sensitivity, allowing the detection of bacteria in environmental samples without the expense of PNA MBs or multilaser flow cytometry. Fluorescent in situ hybridization (FISH) with rRNA-targeted probes is a widely used technique (1, 3, 7) that enable