COMPUTATIONAL MECHANICS OF THE SCLERA AND OPTIC NERVE HEAD (ONH): EFFECTS OF ONH SIZE AND PRESSURE RANGE

ABSTRACT Computational modeling was performed to study how loss of compliance of the eye and abnormally high pressures result in changes in stresses and strains that may impact the optic nerve in diseases such as glaucoma. Hemispherical finite element models of the eye were created in which scleral thickness varied from the equatorial region to the optic nerve head (ONH). Nonhomogeneous material properties were used to model the ONH as a continuous region softer than the adjacent sclera. The ONH and an adjacent buffer zone in the sclera were modeled with enough detail that the size of the ONH could be changed to account for variations observed in humans. The model was provided with appropriate dimensions typical of patients and nonlinear material properties with decreased compliance. Models with different ONH sizes were inflated in small steps to 55 mmHg (7.33 kPa), providing deformed configurations at intermediate pressures of 15, 30 and 45 mmHg, respectively. Color-coded maps of stress and strain components were rendered directly on deformed configurations of the eye model; and animations were produced that show both spatial and temporal variations of stresses and strains as internal pressure increases. Three-dimensional stresses and accompanying finite strains were similar for ONH sizes ranging form 1.5 to 2.5 mm in diameter. Stress and strain differences were estimated as pressure was increased from 15 to 25 mmHg, 30 to 40 mmHg, and 45 to 55 mmHg. Substantial changes occurred in stress and strain differences as the pressure range was varied with large changes occurring in the lowest pressure range for strain components and moderate increases in stress differences as pressures increase. INTRODUCTION High internal eye pressures associated with diseases such as glaucoma may contribute to elevated stresses in the sclera and increased deformation of the ONH. These mechanical factors may result in optic nerve damage emphasizing the need for detailed experimental studies correlated with realistic computational analysis under pathophysiologic conditions [1]

RealTime Audio Analysis Tools for Pd and MSP.”

Abstract Two objects," which run under Max MSP or Pd, do di erent kinds of real-time analysis of musical sounds. Fiddle is a monophonic or polyphonic maximum-likelihood pitch detector similar to Rabiner's, which can also be used to obtain a raw list of a signal's sinusoidal components. Bonk does a bounded-Q analysis of an incoming sound to detect onsets of percussion instruments in a way w h i c h outperforms the standard envelope following technique. The outputs of both objects appear as Max-style control messages. Tools for real-time audio analysis The new real-time patchable software synthesizers have nally brought audio signal processing out of the ivory tower and into the homes of working computer musicians. Now audio can be placed at the center of real-time computer music production, and MIDI, which for a decade was the backbone of the electronic music studio, can be relegated to its appropriate role as a low-bandwidth I O solution for keyboards and other input devices. Many other sources of control input" can be imagined than are provided by MIDI devices. This paper, for example, explores two possibilities for deriving a control stream from an incoming audio stream. First, the sound might c o n tain quasi-sinusoidal partials" and we m i g h t wish to know their frequencies and amplitudes. In the case that the audio stream comes from a monophonic or polyphonic pitched instrument, we w ould like t o b e a b l e t o d etermine the pitches and loudnesses of the components. It's clear that we'll never have a perfect pitch detector, but the fiddle object described here does fairly well in some cases. For the many sounds which don't lend themselves to sinusoidal decomposition, we can still get useful information from the overall spectral envelope. For instance, rapid changes in the spectral envelope turn out to be a much more reliable indicator of percussive attacks than are changes in the overall power reported by a classical envelope follower. The bonk object does a bounded-Q lterbank of an incoming sound and can either output the raw analysis or detect onsets which can then be compared to a collection of known spectral templates in order to guess which o f s e v eral possible kinds of attack has occurred. The fiddle and bonk objects are low t e c h; the algorithms would be easy to re-code in another language or for other environments from the ones considered here. Our main concern is to get predictable and acceptable behavior using easy-to-understand techniques which w on't place an unacceptable computational load on a late-model computer. Some e ort was taken to make fiddle and bonk available on a variety of platforms. They run under Max MSP Macintosh, Pd Wintel, SGI, Linux and fiddle also runs under FTS available on several platforms. Both are distributed with source code; see http: man104nfs.ucsd.edu ~mpuckett for details. 2 Analysis of discrete spectra Two problems are of interest here: getting the frequencies and amplitudes of the constituent partials of a sound, and then guessing the pitch. Our program follows the ideas of Noll 69 and Rabiner 78 . Whereas the earlier pitch~object reported in Puckette 95 departs substantially from the earlier approaches, the algorithm used here adhere more closely to them. First we wish to get a list of peaks with their frequencies and amplitudes. The incoming signal is broken into segments of N samples with N a p o wer of two t ypically between 256 and 2048. A new anal

EPSA11 Perspectives and Foundational Problems in Philosophy of Science

Abstract In this paper I propose a theory of evidence -which I call the Argument Theory -for domains where it is appropriate to demand high standards of rigor, explicitness and transparency, as in evidence for scientific conclusions and especially for evidence-based policy, which is where the need for such a theory first became apparent to me. I then apply the Argument Theory to answer a question that is too seldom asked, and never properly answered, in evidence-based policy where randomized controlled trials (RCTs) are taken as the 'gold standard' for evidence for predicting policy effectiveness: What does it take to makes positive RCT results evidence for policy predictions? The answer it turns out is quite a lot: information is required both about the causal role of the policy in the local circumstances and the helping factors required for it to work there. The Context and the Problem This paper is about evidence, specifically about evidence for effectiveness predictions: predictions that a well-described programme, policy or treatment will work for us, i.e. that the programme will result in an improvement in a wellspecified outcome if we were to implement it in a targeted situation in a specific way -the way we would in fact implement it. Evidence-based policy advocates have invested a great deal of effort over the last few years in evaluating and providing warehouses for storing what they offer as evidence for hypotheses of this form in various areas of concern, warehouses to be visited by 'ordinary' policy makers and analysts

On the Energy Overhead of Mobile Storage Systems

Abstract Secure digital cards and embedded multimedia cards are pervasively used as secondary storage devices in portable electronics, such as smartphones and tablets. These devices cost under 70 cents per gigabyte. They deliver more than 4000 random IOPS and 70 MBps of sequential access bandwidth. Additionally, they operate at a peak power lower than 250 milliwatts. However, software storage stack above the device level on most existing mobile platforms is not optimized to exploit the low-energy characteristics of such devices. This paper examines the energy consumption of the storage stack on mobile platforms. We conduct several experiments on mobile platforms to analyze the energy requirements of their respective storage stacks. Software storage stack consumes up to 200 times more energy when compared to storage hardware, and the security and privacy requirements of mobile apps are a major cause. A storage energy model for mobile platforms is proposed to help developers optimize the energy requirements of storage intensive applications. Finally, a few optimizations are proposed to reduce the energy consumption of storage systems on these platforms

Absolute Pitch and Tone Language: Two New Studies

ABSTRACT Two new studies provide evidence in favor of the hypothesis that absolute pitch is strongly influenced by a speech-related critical period. The first study examined the prevalence of absolute pitch among students in at the University of Southern California's Thornton School of Music, as a function of age of onset of musical training, ethnicity, fluency in speaking a tone language, and country of early music education. Among those of East Asian ethnicity, performance on a test of absolute pitch was strongly correlated with fluency in speaking a tone language. The advantage of early onset of musical training did not interact statistically with the effects of tone language fluency, and further analyses showed that the results could not be explained by country of early music education. The second study investigated the pitch ranges of female speech in two relatively isolated villages in China. These pitch ranges clustered within each village, but differed significantly across the villages, indicating that, at least for speakers of tone language, the pitch range of speech is heavily influenced by an absolute pitch template that is developed through long term exposure to speech in the environment. Implications of these findings are discussed

Presence of ApoE ε4 Allele Associated with Thinner Frontal Cortex in Middle Age

Abstract. The presence of an ApoE ε4 allele (ε4+) increases the risk of developing Alzheimer's disease (AD). Previous studies support an adverse relationship between ε4+ status and brain structure and function in mild cognitive impairment and AD; in contrast, the presence of an ε2 allele may be protective. Whether these findings reflect disease-related effects or pre-existing endophenotypes, however, remains unclear. The present study examined the influence of ApoE allele status on brain structure solely during middle-age in a large, national sample. Participants were 482 men, ages 51-59, from the Vietnam Era Twin Study of Aging (VETSA). T1-weighted images were used in volumetric segmentation and cortical surface reconstruction methods to measure regional volume and thickness. Primary linear mixed effects models predicted structural measures with ApoE status (ε3/3, ε2/3, ε3/4) and control variables for effects of site, non-independence of twin data, age, and average cranial vault or cortical thickness. Relative to the ε3/3 group, the ε3/4 group demonstrated significantly thinner cortex in superior frontal and left rostral and right caudal midfrontal regions; there were no significant effects of ε4 status on any temporal lobe measures