Distributed resource discovery using a context sensitive infrastructure

Distributed Resource Discovery in a World Wide Web environment using full-text indices will never scale. The distinct properties of WWW information (volume, rate of change, topical diversity) limits the scaleability of traditional approaches to distributed Resource Discovery. An approach combining metadata clustering and query routing can, on the other hand, be proven to scale much better. This paper presents the Content-Sensitive Infrastructure, which is a design building on these results. We also present an analytical framework for comparing scaleability of different distribution strategies

Methods for local gravity field approximation

The most widely known modern method for estimating gravity field values from observed data is least-squares collocation. Its advantages are that it can make estimates at arbitrary locations based on irregularly spaced observations, and that it makes use of statistical information about errors in the input data while providing corresponding information about the quality of the output estimates. Disadvantages of collocation include the necessity of inverting square matrices of dimension equal to the number of data values and the need to assume covariance models for the gravity field and the data errors. Fourier methods are an important alternative to collocation; having the advantage of greater computational efficiency, but requiring data estimates to be on a regular grid and not using or providing statistical accuracy information. The GEOFAST algorithm is an implementation of collocation that achieves high computational efficiency by transforming the estimation equations into the frequency domain where an accurate approximation may be made to reduce the workload. The forward and inverse Fast Fourier Transforms (FFTs) are utilized. The accuracy and computational efficiency of the GEOFAST algorithm is demonstrated using two sets of synthetic gravity data: marine gravity for an ocean trench region including wavelengths longer than 200 km; and local land gravity containing wavelengths as short as 5 km. These results are discussed along with issues such as the advantages of first removing reference field models before carrying out the estimation algorithm

Human infectivity trait in <i>Trypanosoma brucei</i>: stability, heritability and relationship to sra expression

Some Trypanosoma brucei lines infect humans whereas others do not because the parasites are lysed by human serum. We have developed a robust, quantitative in vitro assay based on differential uptake of fluorescent dyes by live and dead trypanosomes to quantify the extent and kinetics of killing by human serum. This method has been used to discriminate between 3 classes of human serum resistance; sensitive, resistant and intermediate. TREU 927/4, the parasite used for the T. brucei genome project, is intermediate. The phenotype is expressed in both bloodstream and metacyclic forms, is stably expressed during chromic infections and on cyclical transmission through tsetse flies. Trypanosomes of intermediate phenotype are distinguished from sensitive populations of cells by the slower rate of lysis and by the potential to become fully resistant to killing by human serum as a result of selection or long-term serial passaging in mice, and to pass on full resistance phenotype to its progeny in a genetic cross. The sra gene has been shown previously to determine human serum resistance in T. brucei but screening for the presence and expression of this gene indicated that it is not responsible for the human serum resistance phenotype in the trypanosome lines that we have examined, indicating that an alternative mechanism for HSR exists in these stocks. Examination of the inheritance of the phenotype in F1 hybrids for both bloodstream and metacyclic stages from 2 genetic crosses demonstrated that the phenotype is co-inherited in both life-cycle stages in a manner consistent with being a Mendelian trait, determined by only one or a few genes

A Real-Time, Space Borne Volcano Observatory to Support Decision Making during Eruptive Crises: European Volcano Observatory Space Services

Within the Global Monitoring for Environment and Security (GMES) framework of the European Commission, the EVOSS consortium of academic and industrial partners has created a satellite-based volcano observatory, designed to provide the real-time information support to crisis management. Data from 8 satellite payloads acquired at 6 different down-link stations, are split and automatically processed at 5 locations (in Italy, the Netherlands, Belgium and Germany). The results are sent, in four separate data streams (thermal, volcanic SO2, volcanic ash and ground deformation), to a central system called VVO, the “Virtual Volcano Observatory”. The system operates 24H/24-7D/7 since October 2011 on all volcanoes in Europe, Africa, the Lesser Antilles, and the oceans around them, and during this interval has detected and monitored all eruptions that occurred in this region. EVOSS services are delivered to a group of 14 qualified users in Cabo Verde, Comoros, Congo, Djibouti, Ethiopia, France, Iceland, Montserrat, Tanzania, Uganda and the United Kingdom. Physical modelling of erupive phenomena, with an emphasis on rapid numerical calculations, underpins the satellite monitoring system

Local head loss monitoring using acoustic instrumentation in partially full sewer pipes

After an increase in capital investment in UK sewers to reduce hydraulic capacity problems, the proportion of sewer flooding incidents now linked to blockages has increased. It is clear that if sewer operators are to continue to reduce flooding incidents, then better blockage management is now required. Sewer blockage formation is poorly understood; blockages are intermittent and occur in a number of circumstances. This paper reports on the development of low-cost acoustic instrumentation that can identify the location of a pipe blockage and then estimate the local head loss as a result of the presence of a blockage. A set of experiments were carried out in two full-scale laboratory pipes. The pipes' condition was altered by inserting blockages of different sizes. Acoustic data were recorded and presented in terms of the acoustic energy reflected from the partially blocked pipe. The results of this study show that the total reflected acoustic energy correlates with the measured head loss. A new empirical relation between the reflected acoustic energy and head loss due to a blockage is derived. This knowledge can then be used to estimate the reduction in flow capacity resulting from a blockage based on a single remote measurement

Hepatitis' C virus infection in urban and rural NatallKwaZulu

This study was undertaken to estimate the prevalence of hepatitis C virus (HCV) infection in urban and rural blacks in NataUKwaZulu. Sera from representative community-based samples comprising 176 urban and 441 rural black adults were tested for the presence of anti-HCV. The prevalence of HCV infection was 1,7% (95% confidence interval 0 - 3,6%) among urban and 0,9% (95% confidence interval 0,1 - 1,7% ) among rural blacks. Four (0,9%) of the 466 subjects with evidence of current or past hepatitis B virus (HBV) infection and 3 (2%) of the 151 with no evidence of HBV infection were anti-HCV-positive. The prevalence of HCV infection was low in contrast to the high prevalence of HBV infection among urban and rural blacks in Natal KwaZulu. This suggests that HCV does not have the same main routes of transmission as HBV in this region. Larger scale studies are needed to explore this hypothesis

A Non-invasive wave monitor

This work presents a new acoustical method for remote measurement of the surface characteristics of the dynamic air–water interface in turbulent free-surface flows. The technique uses the reflection of a monochromatic ultrasonic wave by the dynamically rough air–water interface to measure the water surface position. It is found that with careful selection of the acoustical components and their configuration, thephase of the reflected signal responds to the local fluctuations in the fluid interface at the point of specular acoustic reflection. In order for the method to be applicable, three criteria must be satisfied: (1) the dominant wavelength of the surface under investigation must be greater than the first Fresnel zone corresponding to the wavelength and component geometry of the acoustical system; (2) the mean magnitude of the instantaneous local surface gradient must not exceed 0.025; and (3) the root-mean-square wave height must be greater than 1% of the acoustic wavelength. Under these conditions the mean error of the system is within 5% (and usually within 1%) of the acoustic wavelength, and is generally within 10% of the wave amplitude for turbulence generated waves, and 3% of the amplitude for gravity waves. This error may be reduced by optimising the acoustic wavelength for the surface of interest. For turbulent depth limited flows, the surface waves fall well within the criteria, and the absolute errors are independent of wave height, so for larger wave heights, the relative error can be considerably lower. The technique provides a robust system for monitoring the dynamics of free surface fl ows, which is non-invasive, low cost, and low power. The method has been tested on laboratory flows but should be applicable to remote sensing of free surface properties on a local scale in field environments where invasive techniques are difficult to implement such as might be found in coastal, river and wastewater environments

A model of the free surface dynamics of shallow turbulent flows

Understanding the dynamic free surface of geophysical flows has the potential to enable direct inference of the flow properties based on measurements of the free surface. An important step is to understand the inherent response of free surfaces in depth-limited flows. Here a model is presented to demonstrate that free surface oscillatory spatial correlation patterns result from individual surface features oscillating vertically as they advect over space and time. Comparison with laboratory observations shows that these oscillating surface features can be unambiguously explained by simple harmonic motion, whereby the oscillation frequency is controlled by the root-mean-square water surface fluctuation, and to a lesser extent the surface tension. This demonstrates that the observed “complex” wave pattern can be simply described as an ensemble of spatially and temporally distributed oscillons. Similarities between the oscillon frequency and estimated frequency of near-bed bursting events suggest that oscillon behavior is linked with the creation of coherent flow structures

Wind tunnel testing of a generic telescope enclosure

The design of future large optical telescopes must take into account the wind-induced buffeting of the telescope structure caused by large-scale flow structures and turbulence inside the dome. However, estimating the resulting degradation in image quality is difficult due to our relatively poor understanding of the flow inside the dome. Data has been collected in a scaled wind-tunnel test of a telescope enclosure to understand the flow-field around the region near the dome opening where the secondary mirror and supporting structure would be subjected to wind loads. Digital particle image velocimetry (DPIV) data was collected in a vertical plane near the dome opening to obtain mean velocity and fluctuation kinetic energy. In addition, hotwire data was collected along the telescope axis to obtain temporal spectra of the velocity, and flow visualization was used to determine the general flow patterns. In addition to its direct use in telescope modeling and design, this data is of particular value in validation of computational fluid dynamic (CFD) analyses, so that CFD can be used with confidence in future design work

The prevalence of medical reasons for non-participation in the Scottish breast and bowel cancer screening programmes

Objective: Increasing uptake of cancer screening is a priority for health systems internationally, however, some patients may not attend because they are undergoing active treatment for the cancer of interest or have other medical reasons that mean participation would be inappropriate. This study aims to quantify the proportion of non-participants who have a medical reason for not attending cancer screening.&lt;p&gt;&lt;/p&gt; Methods: Medical reasons for not participating in breast and bowel screening were defined a priori on the basis of a literature review and expert opinion. The notes of 700 patients at two GP practices in Scotland were reviewed, to ascertain the prevalence of medical reasons amongst non-participants. Simple proportions and confidence intervals were calculated.&lt;p&gt;&lt;/p&gt; Results: 17.4% of breast and 2.3% of bowel screening non-participants had a medical reason to not participate. The two most common reasons were previous breast cancer follow up (8.86%) and recent mammogram (6.57%).&lt;p&gt;&lt;/p&gt; Conclusion: These patients may not benefit from screening while also being distressed by receiving an invitation. This issue also makes accurate monitoring and target-setting for improving uptake difficult. Further work is needed to estimate robustly the extent to which medical reasons account for screening non-participation in a larger population.&lt;p&gt;&lt;/p&gt