Decentralised Control Flow: A Computational Model for Distributed Systems

PhD ThesisThis thesis presents two sets of principles for the organisation of distributed computing systems. Details of models of computation based on these principles are together given, with proposals for programming languages based on each model of computation. The recursive control flow principles are based on the concept of recursive control flow computing system structuring. A recursive comprises a group of subordinate computing systems connected together by Each subordinate computing system may either be a communications medium. which a a computing system consists of a processing unit, memory some is itself a recursive component, and input/output devices, or computing components control flow system. The memory of all the computing systems within a recursive control flow computing subordinate system are arranged in a hierarchy. Using suitable addresses, any part of the hierarchy is accessible to any sequence of instructions which may be executed by the processing unit of a subordinate computing system. This rise to serious difficulties in the global accessibility gives understanding of programs written the meaning of in a programming language recursive control flow on the model of computation. based Reasoning about a particular program in isolation is difficult because of the potential interference between the execution different programs cannot be ignored . alternative principles, decentralised control flow, restrict the The accessibility of subordinate global the memory components of the computing The basis of the concept of objects forms the systems. principles. Information channels may flow along unnamed between instances of these objects, this being the only way in which one instance of an object may communicate with some other instance of an object. Reasoning particular program written in a programming language about a based on the decentralised control flow model of computation is easier since it is that there will be no interference between the guaranteed execution of different programs.Science and Engineering Research Council of Great Britain, International Computers Limite

The use of platelet-rich plasma in treatment of olfactory dysfunction: A pilot study.

BackgroundOlfactory dysfunction is a prevalent problem with a significant impact on quality of life and increased mortality. Limited effective therapies exist. Platelet-rich plasma (PRP) is an autologous biologic product with anti-inflammatory and neuroprotective effects. This novel pilot study evaluated the role of PRP on olfactory neuroregeneration in patients with hyposmia.MethodsSeven patients who had olfactory loss greater than 6 months in duration, no evidence of sinonasal inflammatory disease, and no improvement with olfactory training and budesonide topical rinses were enrolled in this preliminary study. Patients received a single intranasal injection of PRP into the mucosa of the olfactory cleft. The Sniffin' Sticks olfactory test consisting of threshold, discrimination, and identification measurements (TDI) was administered at the beginning of the study and at 1 and 3 months.ResultsAll patients reported a subjective improvement of their smell shortly after injection but then stabilized. At 3-month post-treatment, two patients with functional anosmia (TDI < 16) did not improve significantly. Five patients with hyposmia (TDI > 16 but <30) showed an improvement with 60% achieving normosmia (TDI > 30) at 3-month follow-up. On average, patients with baseline TDI > 16 improved by 5.85 points with the most significant improvement in the threshold subcomponent. There were no adverse outcomes from intranasal PRP injections.ConclusionPRP appears safe for use in the treatment of olfactory loss, and preliminary data suggest possible efficacy, especially for those with moderate yet persistent loss. Further studies will help determine optimal frequency and duration of use.Level of evidence 2

Wide-field Imaging Interferometry Testbed II: Implementation, Performance, and Plans

The Wide-Field Imaging Interferometry Testbed (WIIT) will provide valuable information for the development of space-based interferometers. This laboratory instrument operates at optical wavelengths and provides the ability to test operational algorithms and techniques for data reduction of interferometric data. Here we present some details of the system design and implementation, discuss the overall performance of the system to date, and present our plans for future development of WIIT. In order to make best use of the interferometric data obtained with this system, it is critical to limit uncertainties within the system and to accurately understand possible sources of error. The WIIT design addresses these criteria through a number of ancillary systems. The use of redundant metrology systems is one of the most important features of WIIT, and provides knowledge of the delay line position to better than 10 nm. A light power detector is used to monitor the brightness of our light sources to ensure that small fluctuations in brightness do not affect overall performance. We have placed temperature sensors on critical components of the instrument, and on the optical table, in order to assess environmental effects on the system. The use of these systems provides us with estimates of the overall system uncertainty, and allows an overall characterization of the results to date. These estimates allow us to proceed forward with WIIT, adding rotation stages for 2-D interferometry. In addition, they suggest possible avenues for system improvement. Funding for WIIT is provided by NASA Headquarters through the ROSS/SARA Program and by the Goddard Space Flight Center through the IR&D Program.Comment: 11 pages, 9 figure

From Molecular Cores to Planet-forming Disks: An SIRTF Legacy Program

Crucial steps in the formation of stars and planets can be studied only at mid‐ to far‐infrared wavelengths, where the Space Infrared Telescope (SIRTF) provides an unprecedented improvement in sensitivity. We will use all three SIRTF instruments (Infrared Array Camera [IRAC], Multiband Imaging Photometer for SIRTF [MIPS], and Infrared Spectrograph [IRS]) to observe sources that span the evolutionary sequence from molecular cores to protoplanetary disks, encompassing a wide range of cloud masses, stellar masses, and star‐forming environments. In addition to targeting about 150 known compact cores, we will survey with IRAC and MIPS (3.6–70 μm) the entire areas of five of the nearest large molecular clouds for new candidate protostars and substellar objects as faint as 0.001 solar luminosities. We will also observe with IRAC and MIPS about 190 systems likely to be in the early stages of planetary system formation (ages up to about 10 Myr), probing the evolution of the circumstellar dust, the raw material for planetary cores. Candidate planet‐forming disks as small as 0.1 lunar masses will be detectable. Spectroscopy with IRS of new objects found in the surveys and of a select group of known objects will add vital information on the changing chemical and physical conditions in the disks and envelopes. The resulting data products will include catalogs of thousands of previously unknown sources, multiwavelength maps of about 20 deg^2 of molecular clouds, photometry of about 190 known young stars, spectra of at least 170 sources, ancillary data from ground‐based telescopes, and new tools for analysis and modeling. These products will constitute the foundations for many follow‐up studies with ground‐based telescopes, as well as with SIRTF itself and other space missions such as SIM, JWST, Herschel, and TPF/Darwin

Are chimpanzees really so poor at understanding imperative pointing? Some new data and an alternative view of canine and ape social cognition

There is considerable interest in comparative research on different species’ abilities to respond to human communicative cues such as gaze and pointing. It has been reported that some canines perform significantly better than monkeys and apes on tasks requiring the comprehension of either declarative or imperative pointing and these differences have been attributed to domestication in dogs. Here we tested a sample of chimpanzees on a task requiring comprehension of an imperative request and show that, though there are considerable individual differences, the performance by the apes rival those reported in pet dogs. We suggest that small differences in methodology can have a pronounced influence on performance on these types of tasks. We further suggest that basic differences in subject sampling, subject recruitment and rearing experiences have resulted in a skewed representation of canine abilities compared to those of monkeys and apes

Atmospheric phase correction using the CARMA paired antennas calibration system

High angular resolution observations are essential to understand a variety of astrophysical phenomena. The resolution of millimeter wave interferometers is limited by large and rapid differential atmospheric delay fluctuations. At the Combined Array for Research in Millimeter-wave Astronomy (CARMA) we have employed a Paired Antenna Calibration System (C-PACS) for atmospheric phase compensation in the extended array configurations (up to 2 km baselines). We present a description of C-PACS and its application. We also present successful atmospheric delay corrections applied to science observations with dramatic improvements in sensitivity and angular resolution

Comparative Population Genetics of the Immunity Gene, Relish: Is Adaptive Evolution Idiosyncratic?

The frequency of adaptive evolution acting on common loci in distant lineages remains an outstanding question in evolutionary biology. We asked whether the immunity factor, Relish, a gene with a history of directional selection in Drosophila simulans, shows evidence of a similar selective history in other Drosophila species. We found only weak evidence of recurrent adaptive protein evolution at the Relish locus in three sister species pairs, suggesting that this key component of the insect immune system has an idiosyncratic evolutionary history in Drosophila

The CARMA Paired Antenna Calibration System: Atmospheric Phase Correction for Millimeter Wave Interferometry and its Application to Mapping the Ultraluminous Galaxy Arp 193

Phase fluctuations introduced by the atmosphere are the main limiting factor in attaining diffraction limited performance in extended interferometric arrays at millimeter and submillimeter wavelengths. We report the results of C-PACS, the Combined Array for Research in Millimeter-Wave Astronomy Paired Antenna Calibration System. We present a systematic study of several hundred test observations taken during the 2009–2010 winter observing season where we utilize CARMA's eight 3.5 m antennas to monitor an atmospheric calibrator while simultaneously acquiring science observations with 6.1 and 10.4 m antennas on baselines ranging from a few hundred meters to ~2 km. We find that C-PACS is systematically successful at improving coherence on long baselines under a variety of atmospheric conditions. We find that the angular separation between the atmospheric calibrator and target source is the most important consideration, with consistently successful phase correction at CARMA requiring a suitable calibrator located ≾6° away from the science target. We show that cloud cover does not affect the success of C-PACS. We demonstrate C-PACS in typical use by applying it to the observations of the nearby very luminous infrared galaxy Arp 193 in ^(12)CO(2-1) at a linear resolution of ≈70 pc (0".12 × 0".18), 3 times better than previously published molecular maps of this galaxy. We resolve the molecular disk rotation kinematics and the molecular gas distribution and measure the gas surface densities and masses on 90 pc scales. We find that molecular gas constitutes ~30% of the dynamical mass in the inner 700 pc of this object with a surface density ~10^4 M_⊙ pc^(−2); we compare these properties to those of the starburst region of NGC 253

Safety issues associated with dietary management in patients with hepatic glycogen storage disease

Introduction Hepatic glycogen storage diseases (GSDs) are a group of inherited disorders of carbohydrate metabolism for which dietary management is the cornerstone. Safety and acute complications associated with dietary management have been poorly documented. We hypothesized that safety issues and complications associated with dietary management are prevalent amongst patients with these ultra-rare disorders. Methods: A questionnaire was developed consisting of 40 questions and was distributed via eight GSD patient organizations from multiple countries. Respondents were (caregivers of) patients with self-reported hepatic GSD. Results: 249 GSD patients from 26 countries responded with a median age of 14.8 years (range: 0.5-66.1). Although management was considered safe by 71% of patients, 51% reported at least one acute complication associated with dietary management, with a total number of 425 reported complications. Most frequently reported causes were: not waking up by an alarm clock (n = 70), forgetting a meal (n = 57) and infections (n = 43). Most frequently reported complications were: hypoglycemia (n = 112), hospital admissions (n = 79) and drowsiness (n = 74). Most complications occurred before the age of 12 years (82%; 637/ 774 total number of reported events) and during night time (63%; 340/536). Only 61% (152/249) of the GSD patients reported using a written emergency protocol. Conclusions: Safety issues and complications associated with dietary management are prevalently reported by (caregivers of) 249 GSD patients. A discrepancy has been observed between the patient's perspective on safety of dietary management and occurrence of complications as a result of dietary management