Integrated temperature compensated Bragg grating refractometer

UV written planar Bragg grating sensors have been shown to form effective refractometers. Here we show that by using the birefringence of an integrated waveguide a temperature insensitive Bragg grating refractometer can be realised

The impact of land surface temperature on soil moisture anomaly detection from passive microwave observations

For several years passive microwave observations have been used to retrieve soil moisture from the Earth's surface. Low frequency observations have the most sensitivity to soil moisture, therefore the current Soil Moisture and Ocean Salinity (SMOS) and future Soil Moisture Active and Passive (SMAP) satellite missions observe the Earth's surface in the L-band frequency. In the past, several satellite sensors such as the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) and WindSat have been used to retrieve surface soil moisture using multi-channel observations obtained at higher microwave frequencies. While AMSR-E and WindSat lack an L-band channel, they are able to leverage multi-channel microwave observations to estimate additional land surface parameters. In particular, the availability of Ka-band observations allows AMSR-E and WindSat to obtain coincident surface temperature estimates required for the retrieval of surface soil moisture. In contrast, SMOS and SMAP carry only a single frequency radiometer and therefore lack an instrument suited to estimate the physical temperature of the Earth. Instead, soil moisture algorithms from these new generation satellites rely on ancillary sources of surface temperature (e.g. re-analysis or near real time data from weather prediction centres). A consequence of relying on such ancillary data is the need for temporal and spatial interpolation, which may introduce uncertainties. Here, two newly-developed, large-scale soil moisture evaluation techniques, the triple collocation (TC) approach and the <i>R</i><sub>value</sub> data assimilation approach, are applied to quantify the global-scale impact of replacing Ka-band based surface temperature retrievals with Modern Era Retrospective-analysis for Research and Applications (MERRA) surface temperature output on the accuracy of WindSat and AMSR-E based surface soil moisture retrievals. Results demonstrate that under sparsely vegetated conditions, the use of MERRA land surface temperature instead of Ka-band radiometric land surface temperature leads to a relative decrease in skill (on average 9.7%) of soil moisture anomaly estimates. However the situation is reversed for highly vegetated conditions where soil moisture anomaly estimates show a relative increase in skill (on average 13.7%) when using MERRA land surface temperature. In addition, a pre-processing technique to shift phase of the modelled surface temperature is shown to generally enhance the value of MERRA surface temperature estimates for soil moisture retrieval. Finally, a very high correlation (<i>R</i><sup>2</sup> = 0.95) and consistency between the two evaluation techniques lends further credibility to the obtained results

DTI Strategic Environmental Assessment Area 4 (SEA4) : sub seabed geology

The SEA 4 region is underlain by continental crust situated on the north-western part of the Eurasian tectonic plate. The oldest continental crust >590Ma (Pre-Cambrian) of interest to oil production, it is divided by a major fault, the Moine Thrust, into ages ranging in age from >2500Ma (Archaean) to the west in which potentially commercial hydrocarbons been discovered and 2500 - 590 Ma (Proterozoic) to the east which is not currently prospective for commerciallyproduced hydrocarbons. The <590Ma sedimentary basins and intervening highs have evolved from pre-, syn- and postdepositional responses to deformation during crustal compression and extension. Many of the modern regional crustal structures retain a NE-SW trend, inherited from events 440-410Ma year ago (Caledonian Orogeny). The results from <65Ma regional NW-SE trending deformation events are also included within the major basin structural configurations. During 60-50 Ma (Late Paleocene to Early Eocene) the region was affected by uplift and in the NW by extrusion of thick volcanic lavas and intrusion of igneous sills. Interactions between historically significant shifts of long-term global climate cooling, an increase in the short-term periodicity and intensity of global climate change and changes to the rates and orientation of crust deformation have been particularly important from 25Ma to the present day (Neogene to Quaternary). These interactions have driven global-to-local changes to basin geological structure, marine circulation, sea level and sediment supply and removal rates and have resulted in the evolutionary changes to submarine basin geometries and lithologies. The modern seabed habitat has thus resulted from the remoulding of inherited basin geometries and lithologies by the processes affecting seabed. The structural history of the region has created a wide variety of potential hydrocarbon trapping mechanisms. The 154-136Ma (Late Jurassic, Kimmeridgian to Ryazanian) Kimmeridge Clay Formation is the principal source rock of the area. The Foinaven and Schiehallion oilfields started production in late 1997 and 1998 respectively both from 60-55Ma (Upper Paleocene) sandstone reservoirs. Geological and technical problems have so far prevented the development of the massive 440-390Ma (Devono-Carboniferous) Clair Field which is the largest undeveloped oilfield on the UK continental shelf. Other hydrocarbon accumulations have been discovered in 245-208Ma (Triassic), 208-146Ma (Jurassic) and 146-65Ma (Cretaceous) intervals in the West Shetland area in the most prospective parts of the SEA 4 region

Measuring the Effects of Surface Features on the Atmospheric Boundary Layer with Instrumented Aircraft

The influence of mesoscale features (e.g., irrigation projects, desert regions, patches of forest, cities, etc.) on the atmosphere is difficult to determine unless the sensors are very numerous or highly mobile. An instrumented aircraft system permits such measurements and was used to determine the influence of lakes and reservoirs, irrigation, a group of forested hills, a small city, and an area of (dry land) nonirrigated agricultural land on the vertical and horizontal characteristics of the lowest layer of the atmosphere. Studies were conducted over portions of southern Alberta, and southern Idaho. Strong sensible heat advection was found to cause high evaporation from a small lake with the formation of a cool air layer which extended well beyond the lee side of the lake. The flux of water vapor over irrigated land was essentially double that over surrounding nonirrigated areas. A small city produced a heat island which delayed development of a temperature inversion for up to 9 h

Definition of valid proteomic biomarkers: a bayesian solution

Clinical proteomics is suffering from high hopes generated by reports on apparent biomarkers, most of which could not be later substantiated via validation. This has brought into focus the need for improved methods of finding a panel of clearly defined biomarkers. To examine this problem, urinary proteome data was collected from healthy adult males and females, and analysed to find biomarkers that differentiated between genders. We believe that models that incorporate sparsity in terms of variables are desirable for biomarker selection, as proteomics data typically contains a huge number of variables (peptides) and few samples making the selection process potentially unstable. This suggests the application of a two-level hierarchical Bayesian probit regression model for variable selection which assumes a prior that favours sparseness. The classification performance of this method is shown to improve that of the Probabilistic K-Nearest Neighbour model

Direct grating writing: single-step Bragg grating and waveguide fabrication for telecommunications and sensing applications

Direct Grating Writing (DGW) has been developed over the past decade as a means of rapidly prototyping waveguides with integrated Bragg grating structures in silica-on-silicon substrates [1]. The technique allows complicated waveguide structures and Bragg grating arrays to be fabricated and characterised in house

Phosphorus nutrition and management – overcoming constraints to wider adoption

The importance of phosphorus nutrition for cattle grazing northern Australian rangelands has been well documented and demonstrated. Phosphorus is clearly one of the most important nutritional deficiencies, within the limitations of potential metabolizable energy intakes, of grazing cattle in the seasonally dry tropics. Nevertheless it appears that only a small proportion of cattle grazing phosphorus deficient pastures are supplemented or otherwise managed to alleviate phosphorus deficiency. Estimated requirements for dietary phosphorus by various classes of cattle grazing tropical pastures have recently been revised (CSIRO 2007). The development of faecal near infrared spectroscopy (F.NIRS) allows the routine estimation of metabolizable energy and nitrogen concentrations in the diet, and thus the potential productivity, of cattle grazing northern rangelands. The concentration of phosphorus in the diet of grazing cattle can be estimated from the concentration of phosphorus in the faeces, at least in cattle not fed phosphorus supplements. Combining estimates of diet metabolizable energy, nitrogen and phosphorus allows estimation whether current needs of the animal are supplied by the diet. Phosphorus-replete cattle have substantial body reserves of phosphorus which can be mobilized, especially in late pregnancy and lactation, to alleviate a dietary deficiency. However, these body reserves need to be replenished in late lactation or post-lactation if mobilization occurs each year. Diagnosis of subclinical phosphorus deficiency in grazing cattle, and prediction of animal responses to phosphorus supplements is difficult. In growing cattle the concentration of inorganic phosphorus in blood (Pi), in the late wet or early dry season, combined with information on diet metabolizable energy and nitrogen concentrations obtained by F.NIRS, provides the most reliable test. In pregnant or lactating cows measurements of faecal phosphorus concentration and F.NIRS provide the best estimate of whether phosphorus intake meets the current needs of the animal. However, estimates of adequacy of phosphorus supply need to also consider possible mobilization of body phosphorus reserves. Indicative responses to provision of phosphorus supplements by cattle grazing pastures ranging from marginal to acute deficiency are summarized. Economic evaluation of benchmark enterprises where cattle are expected to be phosphorus deficient indicate that phosphorus supplementation is highly cost-effective. Major obstacles to more widespread adoption of phosphorus supplementation appear to be lack of knowledge and appreciation by managers of the phosphorus status of their cattle, lack of appreciation of the cost-effectiveness of a phosphorus supplementation particularly for some classes of cattle, and the practical difficulties in implementing phosphorus supplementation during the wet season