Relationship between Allan variances and Kalman Filter parameters

A relationship was constructed between the Allan variance parameters (H sub z, H sub 1, H sub 0, H sub -1 and H sub -2) and a Kalman Filter model that would be used to estimate and predict clock phase, frequency and frequency drift. To start with the meaning of those Allan Variance parameters and how they are arrived at for a given frequency source is reviewed. Although a subset of these parameters is arrived at by measuring phase as a function of time rather than as a spectral density, they all represent phase noise spectral density coefficients, though not necessarily that of a rational spectral density. The phase noise spectral density is then transformed into a time domain covariance model which can then be used to derive the Kalman Filter model parameters. Simulation results of that covariance model are presented and compared to clock uncertainties predicted by Allan variance parameters. A two state Kalman Filter model is then derived and the significance of each state is explained

Integrating social media into routine midwifery services: Maternity Direct+

The use of social media to disseminate and receive health messages has increased over the past ten years, and many women use social media to access pregnancy information. However, the NHS has been slow to integrate consumer facing Internet technologies into routine care services. This article describes an innovative social media project, Maternity Direct+, an Internet midwife employed by Basildon and Thurrock University Hospitals NHS Foundation Trust. The Internet midwife uses Facebook to disseminate health messages and answer non-urgent questions from pregnant women, mothers up to 28 days after birth, and women planning a pregnancy. Findings from the project evaluation demonstrated a high level of demand for a responsive, evidence-based, non-urgent information and advice service for pregnant women and new mothers, and high levels of user satisfaction. The authors conclude that social media can be integrated into routine midwifery services and used to complement existing communication channels

Ternary nucleation of H_2SO_4, NH_3 and H_2O

A classical theory of the ternary homogeneous nucleation of sulfuric acid—ammonia—water is presented. For NH3 mixing ratios exceeding 1 ppt, the presence of ammonia enhances the binary (sulfuric acid—water) nucleation rate by several orders of magnitude. However, the limiting component for ternary nucleation—as for binary nucleation—is sulfuric acid. The sulfuric acid concentration needed for significant ternary nucleation is several orders of magnitude below that required in binary case

Pattern Formation by Boundary Forcing in Convectively Unstable, Oscillatory Media With and Without Differential Transport

Motivated by recent experiments and models of biological segmentation, we analyze the exicitation of pattern-forming instabilities of convectively unstable reaction-diffusion-advection (RDA) systems, occuring by means of constant or periodic forcing at the upstream boundary. Such boundary-controlled pattern selection is a generalization of the flow-distributed oscillation (FDO) mechanism that can include Turing or differential flow instability (DIFI) modes. Our goal is to clarify the relationships among these mechanisms in the general case where there is differential flow as well as differential diffusion. We do so by analyzing the dispersion relation for linear perturbations and showing how its solutions are affected by differential transport. We find a close relationship between DIFI and FDO, while the Turing mechanism gives rise to a distinct set of unstable modes. Finally, we illustrate the relevance of the dispersion relations using nonlinear simulations and we discuss the experimental implications of our results.Comment: Revised version with added content (new section and figures added), changes to wording and organizatio

R.B. Polygraphe

Introduction to the special issu

Archeological Testing within the Right-of-Way of FM 1929, at Site 41CN218, Coleman County, and in the Vicinity of Site Complex 41CC48/49/50/51 and Site 41CC52, and Site 41CC246, Concho County, Texas

The State Department of Highways and Public Transportation (SDHPT) conducted archaeological testing within the right-of-way of FM 1929 at site 41CN218 in Coleman County, and in the vicinity of site complex 41CC48/49/50/51 and 41CC52 in Concho County. Intensive surface survey and mapping was also undertaken at site 41CC246 in Concho County. This report details the work undertaken, and summarizes the cultural sequence of the area. Excavations at site 41CN218 did not reveal any evidence of discrete cultural stratigraphy. Rather it appeared that artifacts were scattered throughout an upper brownish soil horizon, which in places reached depths of about 2 meters. The only feature tentatively recognized consisted of a limestone hearth. This was not associated with any diagnostic artifacts, identifiable cultural living surface, or any ash or charcoal. None of the artifacts recovered from the excavations were temporally or culturally diagnostic. For the most part, artifacts consisted of lithic debitage, with a few utilized flakes, one uniface, and two very small biface fragments. The nature of the debitage suggests that lithic activities were largely confined to final tool manufacture, at least within that part of the site tested. The utilized flakes suggest that scraping, cutting, and perhaps graving or piercing activities took place on the site. Fauhal remains consisted of a few small fragments of fossilized bone which could not be directly associated with cultural remains, and highly weathered fragments of mussel shell. The nature of the recovered remains is not conducive to the identification of specific activity areas, or other horizontal cultural patterning. Gross artifact counts indicate a higher density of artifacts along the western margin of the right-of-way. However, it was obvious from surface inspection of the area that the right-of-way crossed the eastern margin of the site, and that artifacts appeared with considerably greater frequency to the west of the right-of-way. On the basis of the excavations conducted, it is believed that those portions of the site within the highway right-of-way are not worthy of designation as a State Archeological Landmark. Excavations within the FM 1929 right-of-way in the vicinity of site complex 41CC48/49/50/51 and site 41CC52 failed to reveal any buried cultural materials, cultural features, or other evidence of buried cultural strata. Surface examination revealed a few scattered non-diagnostic cultural artifacts, but all were in plow-disturbed deposits. It is, therefore, believed that those portions of the sites within the highway right-of-way are not worthy of designation as a State Archeological Landmark. Survey within the FM 1929 right-of-way at site 41CC246 revealed that the area was extremely eroded. Although the investigations were primarily concerned with the historic component, scattered prehistoric lithic debitage, none diagnostic, was observed on the surface. This sparse scatter extended into site 41CC52, with no apparent discontinuity. Site mapping indicated that the concentration of rock and rubble associated with a house foundation was essentially outside the right-of- way, as was the accompanying sheet scatter of historic artifacts. Given the eroded nature of the area, the lack of intact features within the right-of-way, and previous impacts, it is believed that those portions of the site within the highway right-of-way are not worthy of designation as a State Archeological Landmark

Collaborative multidisciplinary learning : quantity surveying students’ perspectives

The construction industry is highly fragmented and is known for its adversarial culture, culminating in poor quality projects not completed on time or within budget. The aim of this study is thus to guide the design of QS programme curricula in order to help students develop the requisite knowledge and skills to work more collaboratively in their multi-disciplinary future workplaces. A qualitative approach was considered appropriate as the authors were concerned with gathering an initial understanding of what students think of multi-disciplinary learning. The data collection method used was a questionnaire which was developed by the Behaviours4Collaboration (B4C) team. Knowledge gaps were still found across all the key areas where a future QS practitioner needs to be collaborative (either as a project contributor or as a project leader) despite the need for change instigated by the multi-disciplinary (BIM) education revolution. The study concludes that universities will need to be selective in teaching, and innovative in reorienting, QS education so that a collaborative BIM education can be effected in stages, increasing in complexity as the students’ technical knowledge grows. This will help students to build the competencies needed to make them future leaders. It will also support programme currency and delivery

Size-induced distortions in perceptual maps of visual space

In order to interact with our environment, the human brain constructs maps of visual space. The orderly mapping of external space across the retinal surface, termed retinotopy, is maintained at subsequent levels of visual cortical processing and underpins our capacity to make precise and reliable judgments about the relative location of objects around us. While these maps, at least in the visual system, support high precision judgments about the relative location of objects, they are prone to significant perceptual distortion. Here, we ask observers to estimate the separation of two visual stimuliVa spatial interval discrimination task. We show that large stimulus sizes require much greater separation in order to be perceived as having the same separation as small stimulus sizes. The relationship is linear, task independent, and unrelated to the perceived position of object edges. We also show that this type of spatial distortion is not restricted to the object itself but can also be revealed by changing the spatial scale of the background, while object size remains constant. These results indicate that fundamental spatial properties, such as retinal image size or the scale at which an object is analyzed, exert a marked influence on spatial coding