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Background: The multimorbid burden and use of systemic immunosuppressants in people with psoriasis may confer greater risk of adverse outcomes of coronavirus disease 2019 (COVID-19), but the data are limited. Objective: Our aim was to characterize the course of COVID-19 in patients with psoriasis and identify factors associated with hospitalization. Methods: Clinicians reported patients with psoriasis with confirmed/suspected COVID-19 via an international registry, Psoriasis Patient Registry for Outcomes, Therapy and Epidemiology of COVID-19 Infection. Multiple logistic regression was used to assess the association between clinical and/or demographic characteristics and hospitalization. A separate patient-facing registry characterized risk-mitigating behaviors. Results: Of 374 clinician-reported patients from 25 countries, 71% were receiving a biologic, 18% were receiving a nonbiologic, and 10% were not receiving any systemic treatment for psoriasis. In all, 348 patients (93%) were fully recovered from COVID-19, 77 (21%) were hospitalized, and 9 (2%) died. Increased hospitalization risk was associated with older age (multivariable-adjusted odds ratio [OR] = 1.59 per 10 years; 95% CI = 1.19-2.13), male sex (OR = 2.51; 95% CI = 1.23-5.12), nonwhite ethnicity (OR = 3.15; 95% CI = 1.24-8.03), and comorbid chronic lung disease (OR = 3.87; 95% CI = 1.52-9.83). Hospitalization was more frequent in patients using nonbiologic systemic therapy than in those using biologics (OR = 2.84; 95% CI = 1.31-6.18). No significant differences were found between classes of biologics. Independent patient-reported data (n = 1626 across 48 countries) suggested lower levels of social isolation in individuals receiving nonbiologic systemic therapy than in those receiving biologics (OR = 0.68; 95% CI = 0.50-0.94). Conclusion: In this international case series of patients with moderate-to-severe psoriasis, biologic use was associated with lower risk of COVID-19–related hospitalization than with

Background: Basenjis are considered an ancient dog breed of central African origins that still live and hunt with tribesmen in the African Congo. Nicknamed the barkless dog, Basenjis possess unique phylogeny, geographical origins and traits make understanding their genome structure relative to more modern dog breeds of great interest. Here, we report the de novo assemblies of two Basenji: a female, China, and a male, Wags. We conduct pairwise comparisons and report structural variations between assembled genomes of three dog breeds: Basenji (CanFam_Bas), Boxer (CanFam3.1) and German Shepherd Dog (GSD) (CanFam_GSD). We then align representative whole genome sequences from 58 dog breeds and show the importance of genome reference when assessing variation among dog breeds. Results: Here we present two high quality Basenji genome assemblies, CanFam_Bas (China) and Wags. CanFam_Bas is superior to CanFam v3,1 is terms of genome contiguity and comparable overall to the high quality CanFam_GSD assembly. The increasing number of available canid reference genomes allows us to examine the impact the choice of reference genome makes with regard to reference genome quality and breed relatedness. By aligning short read data from 58 representative dog breeds to three reference genomes, we demonstrate how the choice of reference genome significantly impacts both read mapping and variant detection. Further, we generate a conservative list of structural variant calls using a consensus of both Pacific Bioscience and Oxford Nanopore long reads to identify large structural breed differences. Collectively this work highlights the importance the choice of reference genome makes in canid variation studies. Conclusions: The growing number of high-quality canid reference genomes means the choice of reference genome is an increasingly critical decision in subsequent canid variant analyses. The basal position of the Basenji makes it suitable for variant analysis for targeted applications of sp

During its approach to asteroid (101955) Bennu, NASA's Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft surveyed Bennu's immediate environment, photometric properties, and rotation state. Discovery of a dusty environment, a natural satellite, or unexpected asteroid characteristics would have had consequences for the mission's safety and observation strategy. Here we show that spacecraft observations during this period were highly sensitive to satellites (sub-meter scale) but reveal none, although later navigational images indicate that further investigation is needed. We constrain average dust production in September 2018 from Bennu's surface to an upper limit of 150 g s-1 averaged over 34 min. Bennu's disk-integrated photometric phase function validates measurements from the pre-encounter astronomical campaign. We demonstrate that Bennu's rotation rate is accelerating continuously at 3.63 ± 0.52 × 10-6 degrees day-2, likely due to the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, with evolutionary implications.

We report on the activities related to the IAG Subcommission 1.3f “Regional Reference Frame for Antarctica”. Campaign-style GPS observations have been carried out since 1995. Based on the Bernese GNSS Software the latest analysis yields results for about 30 stations aligned to the terrestrial reference frame solution IGS08. The obtained station motions are discussed in the context of plate kinematics and glacial-isostatic adjustment. It is demonstrated that the activities are a valuable contribution both to the ITRF densification in Antarctica and to geodynamic research., QC 20161101

Biological transfer of nutrients and materials between linked ecosystems influences global carbon budgets and ecosystem structure and function. Identifying the organisms or functional groups that are responsible for nutrient transfer, and quantifying their influence on ecosystem structure and carbon capture is an essential step for informed management of ecosystems in physically distant, but ecologically linked areas. Here, we combine natural abundance stable isotope tracers and survey data to show that mid-water and bentho-pelagic-feeding demersal fishes play an important role in the ocean carbon cycle, bypassing the detrital particle flux and transferring carbon to deep long-term storage. Global peaks in biomass and diversity of fishes at mid-slope depths are explained by competitive release of the demersal fish predators of mid-water organisms, which in turn support benthic fish production. Over 50% of the biomass of the demersal fish community at depths between 500 and 1800 m is supported by biological rather than detrital nutrient flux processes, and we estimate that bentho-pelagic fishes from the UK-Irish continental slope capture and store a volume of carbon equivalent to over 1 million tonnes of CO2 every year.

Mathematical models of mosquito-borne pathogen transmission originated in the early twentieth century to provide insights into how to most effectively combat malaria. The foundations of the Ross–Macdonald theory were established by 1970. Since then, there has been a growing interest in reducing the public health burden of mosquito-borne pathogens and an expanding use of models to guide their control. To assess how theory has changed to confront evolving public health challenges, we compiled a bibliography of 325 publications from 1970 through 2010 that included at least one mathematical model of mosquito-borne pathogen transmission and then used a 79-part questionnaire to classify each of 388 associated models according to its biological assumptions. As a composite measure to interpret the multidimensional results of our survey, we assigned a numerical value to each model that measured its similarity to 15 core assumptions of the Ross–Macdonald model. Although the analysis illustrated a growing acknowledgement of geographical, ecological and epidemiological complexities in modelling transmission, most models during the past 40 years closely resemble the Ross–Macdonald model. Modern theory would benefit from an expansion around the concepts of heterogeneous mosquito biting, poorly mixed mosquito-host encounters, spatial heterogeneity and temporal variation in the transmission process.

One of the challenges facing the gold industry in the twenty-first century is the continuing need to identify new reserves of economically treatable ores. Discoveries of large, metallurgically simple orebodies are becoming increasingly rarer, forcing companies to investigate options for the processing of ores which may present recovery, economic and/or environmental issues, requiring innovative approaches to their treatment. Ores which contain naturally occurring carbonaceous material ('pregrobbing ores') is an example of one such ore type. Newmont's Jundee operation contains zones of carbonaceous ore within the oxidised ore body. A program consisting of detailed laboratory work and extensive plant trials has been undertaken to assess the options of the processing of this material. Laboratory tests demonstrated the advantage of carbon-in-leach (CIL) over direct cyanide leaching and carbon-in-pulp (CIP) for treatment of these ores. The laboratory program identified several factors which would enhance overall gold recoveries when preg-robbing ore was being processed, including: keeping preg-robbing ore separate from non-graphitic ore, maximising gravity recovery and ensuring the plant operates in 'pure' CIL mode i.e. no leaching before first adsorption tank. Plant trials were undertaken to assess the economic sustainability of treating moderate preg-robbing ores through a modified gravity/leach/adsorption circuit. Results indicated that where good operational control of the circuit was maintained to ensure high gravity recovery, minimal leaching prior to carbon contact and maintenance of good, active carbon inventory, then acceptable and sustainable overall gold recoveries could be obtained. However, plant trials did not produce gold recovery as high as laboratory tests. Using these relatively simple plant modifications potentially allows a plant to treat ores with preg-robbing index (PRI) values up to 1. When PRI values rise to 1·3-1·6 leach recoveries can drop from.

An investigation into orientation preferences shown by actin fibres within ex-situ actin as imaged by Atomic Force Microscopy (AFM) is described. Actin is a primary cytoskeletal component and is believed to play a vital role in cell structure. Actin structure images measured by AFM were analysed using automated pre-processing steps. These steps were identical for the production of an initial binary image, which was then processed by both Hough transformation and thinning. Results obtained question the validity of using the Hough transform approach, as bias could not easily be eliminated, and hence the Hough transform method was deemed to be unsuitable for this application and instead the thinning technique was used to identify and locate actin orientation within the AFM images. The results show that polymerised ex-situ actin fibres appears to display a bimodal distribution of orientation, with a 90 degree separation, with a significant co-efficient of bimodality of 0.656.

AUSGeoid09 is the new Australia-wide gravimetric quasigeoid model that has been a posteriori fitted to the Australian Height Datum (AHD) so as to provide a product that is practically useful for the more direct determination of AHD heights from Global Navigation Satellite Systems (GNSS). This approach is necessary because the AHD is predominantly a third-order vertical datum that contains a ~1 m north-south tilt and ~0.5 m regional distortions with respect to the quasigeoid, meaning that GNSS-gravimetric-quasigeoid and AHD heights are inconsistent. Since the AHD remains the official vertical datum in Australia, it is necessary to provide GNSS users with effective means of recovering AHD heights. The gravimetric component of the quasigeoid model was computed using a hybrid of the remove-compute-restore technique with a degree-40 deterministically modified kernel over a one-degree spherical cap, which is superior to the remove-compute-restore technique alone in Australia (with or without a cap). This is because the modified kernel and cap combine to filter long-wavelength errors from the terrestrial gravity anomalies. The zero-tide EGM2008 global gravitational model to degree and order 2190 was used as the reference field.Other input data are: ~1.4 million land gravity anomalies from Geoscience Australia, 1'x1' DNSC2008GRA altimeter-derived gravity anomalies offshore, the 9"x9" GEODATA-DEM9S Australian digital elevation model, and a readjustment of Australian National Levelling Network (ANLN) constrained to the CARS2006 dynamic ocean topography model. In order to determine the numerical integration parameters for the modified kernel, the gravimetric component of AUSGeoid09 was compared with 911 GNSS-observed ellipsoidal heights at benchmarks. The standard deviation of fit to the GNSS-AHD heights is 222 mm, which dropped to 134 mm for the readjusted GNSS-ANLN heights, showing that careful consideration now needs to be given to the quality of the levelling data used to

In an absolute sense, AUSGeoid09 is an order of magnitude more accurate than AUSGeoid98 at converting ellipsoidal heights to Australian Height Datum (AHD) heights and vice versa. Results of this study show AUSGeoid09 can be used to compute AHD heights from Global Navigation Satellite System (GNSS) ellipsoidal heights with an uncertainty of less than +/-0.03 m (one sigma). The improvement is largely due to the inclusion of a geometric component in AUSGeoid09 that accountsfor the spatially varying offset between a gravimetric quasigeoid model and the AHD. This geometric component was calculated using least squares collocation in cross validation mode and then added to the gravimetric quasigeoid. Although previous AUSGeoid models were used to convert GNSS ellipsoidal heights to the AHD and vice versa, none until now have accounted for the gravimetric quasigeoid to AHD offsets. This offset is a consequence of how the AHD was realised and has commonly resultedin misfits of ~0.5 m or more. When used with GNSS technology, AUSGeoid09 can replace the need for traditional third-order levelling (Class LC; 12 roo k) in many situations. Relative tests of AUSGeoid09 over a continent-wide set of over 20 million baselines showed that it can deliver better than Class LC tolerances in 99 percent of cases. The model accepts a user?s GDA94 latitude, longitude and ellipsoidal height and returns an AHD height and deviations of the vertical. AUSGeoid09 is now availablefree-of-charge on the Geoscience Australia website (http://www.ga.gov.au/geodesy/ausgeoid/nvalcomp.jsp).

Introduction: Ecological resilience can be defined as the ability of a system to absorb a disturbance so that basic function and structure are retained. Resilience of a system is tested when impacted upon by a disturbance that has the potential to fundamentally and irreversible change the original identity of the system (Holling 1973; Folke et al. 2004). Plant pathogens playa significant role is determining vegetation dynamics at a range of ecological, spatial and temporal scales. However, there is little research on how plant pathogens change vegetation at a community and landscape scale. Phytophthora cinnamomi is an introduced invasive soil borne plant pathogen that is internationally recognised for its destructive impact upon native vegetation communities (Shearer and Smith 2000). Despite the pathogen being recognised as a Key Threatening Process, documentation of its impact on vegetation community composition, structure and function is limited. The pathogen is of particular concern in South-Western Australia where 40% of the flora is susceptible, of which 14% are listed as highly susceptible (Shearer et al. 2007).

We aim to assess current knowledge, and identify gaps in knowledge concerning bell-miner-associated dieback (BMAD) in south-eastern Australia. We review BMAD as a form of forest dieback, and bell miner and psyllid interrelations. We then consider indirect and direct causal factors associated with local functional scales (tree crown), and finally, indirect and direct causal factors associated with broader functional scales (forest stand and landscape processes). This paper emphasises published literature and is a summary of a more detailed report prepared for the BMAD working group which explicitly included personal communications with many researchers, managers and members of conservation groups and the timber industry. We conclude that BMAD is a significant threat to the sustainability of the moist eucalypt forests of north-eastern NSW and south-eastern Queensland, and to biodiversity conservation at a national scale. There are serious deficiencies in the information base for most BMAD issues. While there are clear interactions between bell miners and psyllids, there are many other, less well quantified interactions that may be of greater significance to the development of the problem. We suggest that management and research efforts towards solutions urgently target disturbances that lead to changes in forest canopy structure, but there is unlikely to be a single or simple management solution. An integrated management program will be necessary as concentration on particular management regimes in isolation is unlikely to resolve the BMAD problem because BMAD is associated with interacting disturbances.

The phrase 'a forest conscienceness' was used in a major statement made by Charles Lane Poole, Western Australia's Conservator of Forests from 1916-1921, for the 1920 British Empire Forestry Conference. It is both relevant and contemporary at the beginning of the 21st century. We chose it as the conference theme to encourage engagement with both a conscious awareness of forests and their values, and a sense of moral responsibility toward forest management. It stimulated a broad range of lively contributions that emphasized mainly the 'awareness' aspect, although some authors addressed 'moral responsibility'. Perhaps 'conscienceness', like sustainability, is an evolving concept not yet fully mature. It warrants further engagement.

We review the history of forest management in two southern hemisphere foresttypes: Western Australia’s jarrah Eucalyptus marginata forests and the Afromontane forests ofsouthern Africa to determine approaches for achieving sustainable forest management. We arguethat despite major differences in the ecology and biogeography of these two forest types, a sharedpattern in the history of exploitation may provide lessons for achieving sustainable managementacross forest types. While advanced silvicultural understanding has long been achieved in both for-est types, this in itself has not led to either sustainable management or to public acceptance of forestmanagement regimes. In both areas an early, rapid expansion of uncontrolled timber removal and inthe number of operating timber mills was followed by controlled exploitation, a rapid decline in thenumbers of mills and, more recently, a general decline in yield. In neither case was increased con-cern about conservation responsible for the reduction in either yield or in employment in the indus-try. Rather, in WA jarrah forests, amendments in purpose and tenure were subsequent to the loss ofmost mills and towns, while in southern Africa’s Afromontane forests, timber workers were pen-sioned by 1939 because of scanty remaining merchantable timber. In the jarrah forests, we believethat the conflict generated by conservation concerns, reduced timber industry employment, and re-duced benefits flowing to the communities adjacent to the logged forests, has fueled dissatisfactionwith forest management outcomes. This has led to a new process in the preparation of forest man-agement plans. Increased accountability and more realistic expectations of timber yield followingproductivity declines may mean the current plan for the forests of Western Australia can be used asan example to achieve sustainability in Mediterranean forest ecosystems. However, general accep-tance of management regimes may not be achieved until the scale of loggi

In 1996, Government directives began a transition to conform logging in Western Australia’s State forests to principles of ecologically sustainable forest management (ESFM). To place this in a historical context, we reviewed the history of the logging of jarrah Eucalyptus marginata forests to determine whether the volume of timber extracted and the main forest management practices employed was consistent with components of ESFM. While quantitative assessment proved difficult, usually the timber cut considerably exceeded the estimated annual increment of forested lands. Overcutting often distressed professionals, who strove to regulate logging despite social, political and economic pressures. Furthermore, despite recent major reductions in permissible timber cut, areas of productive State forest have declined after conversion to alternative vestings. Thus it is important to prevent overcutting continuing in the remaining production forests. Too few data exist on the health or condition of forest ecosystems before logging to document subtle impacts. However, overcutting has interacted with broad-scale threatening processes in their impacts on forest fauna. These changes are all associated with reluctance to invoke effective adaptive management in association with the precautionary principle. The historical survey suggests that ESFM cannot be achieved without a socio-political will to assert long-term sustainable practice in the face of short-term goals. This could be achieved in the current preparation of a new forest management plan for Western Australia.

We review recent studies of the impacts of disturbance on the fauna of the jarrah forest, south-western Australia. In particular, we examine five case studies that provide alternative approaches to researching disturbance impacts. Assessing site-based studies of patterns of fire regimes lead us to argue that point measures of frequency are inadequate to understand scale and pattern across landscapes. Rather, extrapolating from site-based data to draw conclusions on landscape-scale changes may obscure fine-scale heterogeneity in disturbance, which is critical to the conservation of biodiversity. We review species-based studies and conclude that assessments of demographic trends are more effective than surveys in determining impacts, and providing early warning of declines because they highlight threatening processes. Furthermore, risk analysis, when critical aspects of the biology of participating species are weakly known, may lead to misclassification of species and poor decisions on conservation priorities. The review of recent impact studies of logging on jarrah forest fauna demonstrates that logging interacts with predation by foxes to threaten arboreal mammals. Hence, measures to protect threatened vertebrates benefit many species. However, while concentrating on proximate causes of fauna decline produces immediate conservation gains, long-term conservation requires an understanding of both proximate and ultimate causes and their interaction. We urge the acquisition of reliable, site-based demographic data that allows predictive modelling for species, and hence testing of alternative hypotheses regarding impact, distribution and decline. We also seek the integration of data and approaches to enable landscape-scale patterns to be discerned and interpreted for effective conservation planning.

The AUSGeoid98 gravimetric geoid model of Australia has been computed using data from the EGM96 global geopotential model, the 1996 release of the Australian gravity database, a nationwide digital elevation model, and satellite altimeter-derived marine gravity anomalies. The geoid heights are on a 2 by 2 arc-minute grid with respect to the GRS80 ellipsoid, and residual geoid heights were computed using the 1-D fast Fourier transform technique. This has been adapted to include a deterministically modified kernel over a spherical cap of limited spatial extent in the generalised Stokes scheme. Comparisons of AUSGeoid98 with GPS and Australian Height Datum (AHD) heights across the continent give an RMS agreement of -0.364 m, although this apparently large value is attributed partly to distortions in the AHD.

There is widespread agreement that the indigenous forests of south-western Australia are an important refuge for wildlife in an otherwise extensively cleared landscape and that sustainable use of these forests is possible. Nevertheless, principles-based theses that have been proposed for assessing sustainability of forest use are of limited value unless they include assessable criteria for application. We argue that it is important to recognise that ecological science, like other disciplines is value-laden and that a statement of values is an important part of the scientific process. Furthemore, we believe that there is presently inadequate evidence to judge whether or not the current forest use is sustainable. Several areas-of empirical work are suggested to resolve the outstanding issues.

Paracetamol is an effective, simple analgesic that is well tolerated by adults and children at thera­peutic doses. In many countries it is available without prescription. Unfortunately, its ready availabil­ity is associated with episodes of poisoning that prompt 3.3% of inquiries to US regional poisons centres, 10% of inquiries to the UK National Poisons Information Service, and up to 43% of all admissions to hospital with self poisoning in the United Kingdom.3 In the United States paracetamol alone accounted for 4.1% of deaths from poisoning reported to American poisons centres in 1997. Most deaths are associated with deliberate self poisoning, but therapeutic mis­adventures do occur rarely, in both adults and children.

This study measures the anxiety levels in 100 parents of children scheduled for elective surgery at the Royal Aberdeen Children's Hospital. Anxiety levels were quantified using the Leeds scale for self-assessment of anxiety. Forty-two per cent of parents were significantly anxious. Mothers were identified as being more pathologically anxious than fathers. The 'anxious' parents were specifically more anxious about the surgery anaesthesia, postoperative pain and treatment, and hospitalisation in general. All parents, whether identified as anxious or not, agreed on factors likely to reduce anxiety: pre-operative information from staff, being able to accompany their child to the operating theatre and being present at induction of anaesthesia.

Laboratory studies to improve understanding of the coating's role in aluminium electrometallurgy demonstrated a number of properties. The thermal expansion was somewhat higher than for carbon materials, electrical conductivity was of the same order as that of graphite and porosity was around 30%. The coating protected by infiltrated Al exhibited a high resistance to Na attack. The material adhered strongly to carbon materials even after thermal cycling. Other properties included high abrasion resistance and wettability by liquid aluminium. The coating's effective barrier action against Na penetration is due to its ability to form a stable liquid Al layer in the pores, so that Al, electrolyte and Na-stabilising carbon are no longer in close contact and Na penetration is limited by slow diffusion through the Al layer., Laboratory studies to improve understanding of the coating's role in aluminium electrometallurgy demonstrated a number of properties. The thermal expansion was somewhat higher than for carbon materials, electrical conductivity was of the same order as that of graphite and porosity was around 30%. The coating protected by infiltrated Al exhibited a high resistance to Na attack. The material adhered strongly to carbon materials even after thermal cycling. Other properties included high abrasion resistance and wettability by liquid aluminium. The coating's effective barrier action against Na penetration is due to its ability to form a stable liquid Al layer in the pores, so that Al, electrolyte and Na-stabilising carbon are no longer in close contact and Na penetration is limited by slow diffusion through the Al layer.

Mine project permitting must be carefully managed to prevent excessive delays, costly compliance conditions, significant future contingent liabilities, damaged stakeholder relationships, or, possibly, rejection of the mining proposal. A checklist is presented for a strategic approach to permitting, involving scoping studies, understanding the legislative and regulatory framework, stating the company's objective and business plans, identifying key stakeholders, building trust, identifying pivotal concerns, public relations, consultation with stakeholders, developing integrity, defining best practice and undertaking peer review. Brief discussion is presented of permitting at the Cadia copper-gold project in New South Wales., Mine project permitting must be carefully managed to prevent excessive delays, costly compliance conditions, significant future contingent liabilities, damaged stakeholder relationships, or, possibly, rejection of the mining proposal. A checklist is presented for a strategic approach to permitting, involving scoping studies, understanding the legislative and regulatory framework, stating the company's objective and business plans, identifying key stakeholders, building trust, identifying pivotal concerns, public relations, consultation with stakeholders, developing integrity, defining best practice and undertaking peer review. Brief discussion is presented of permitting at the Cadia copper-gold project in New South Wales.

Phaclofen, which is the phosphonic acid analogue of the GABAB agonist (RS)-3-(4-chlorophenyl)-4-aminobutyric acid (baclofen), is a GABAB antagonist. As part of our studies on the structural requirements for activation and blockade of GABAB receptors, we have resolved phaclofen using chiral chromatographic techniques. The absolute stereochemistry of (-)-(R)-phaclofen was established by X-ray crystallographic analysis. (-)-(R)-Phaclofen was shown to inhibit the binding of [3H]-(R)-baclofen to GABAB receptor sites on rat cerebellar membranes (IC50 = 76 +/- 13 microM), whereas (+)-(S)-phaclofen was inactive in this binding assay (IC50 > 1000 microM). (-)-(R)-Phaclofen (200 microM) was equipotent with (RS)-phaclofen (400 microM) in antagonizing the action of baclofen in rat cerebral cortical slices, while (+)-(S)-phaclofen (200 microM) was inactive. The structural similarity of the agonist (R)-baclofen and the antagonist (-)-(R)-phaclofen suggests that these ligands interact with the GABAB receptor sites in a similar manner. Thus, it may be concluded that the different pharmacological effects of these compounds essentially result from the different spatial and proteolytic properties of their acid groups.

The purpose of this thesis was to develop a suitable filter model and failure detection/identification (FDI) processor as a basis for a fully simulated adaptive tactical navigation (ATN) system. A 52-state truth error model was developed from which a 26-state filter error model was derived. The measurement process uses a six measurement satellite positioning system (three velocity measurements and three position measurements), a three measurement Doppler radar, and a terrain correlation system. The filter residuals for the different measurement processes are then used in N-step likelihood function computations to observe the residual behavior. Two different testing criteria have been developed for failure declaration. Simple threshold establishment and the tracking of the likelihood function N-step characteristics are used for this purpose. Based on the statistics of the observed failure characteristics, an isolation processor isolates the fault and makes the correct identification. Originator-Supplied Keywords include: Detection, Detectors, Kalman Filtering, Isolation, Filters, and Failure.

A one-twelfth scale aeroacoustic model of a proposed engineering acoustic research facility has been tested to assess the background noise levels in the anechoic measurement area, and to develop a suitable exhaust collector for deflected jet conditions. The facility comprises an open circuit, open jet wind tunnel with an anechoic space surrounding the test section. Collector configurations with acceptably low background noise and low sensitivity to jet deflection have been defined, but these features were achieved at the expense of some aerodynamic efficiency.

Mass spectrometry is a powerful technique for the study of any process involving volatilization. This review mainly considers the use of mass spectrometry in analysing the effusates from Knudsen cells at high temperatures. The theoretical and experimental requirements for each of the various components of the system are reviewed. A number of significant advances have been made in the past five years and these are discussed where applicable. Similarly, the survey of the applications of Knudsen cell mass spectrometry is also intended to update the review literature. Emphasis is placed on metallurgical applications, and the discussion is divided into sections dealing specifically with the determination of activities in alloys, vaporization behaviour of metals and oxides, and vaporization behaviour of salts. (Author), Revision of report dated 12 Dec 73.

An instrument is presented which can record, untended, ground temperatures under severe environmental conditions for extended periods of time.

Contents: The galvanic compatibility of graphite composites and structural metals; Electrochemical investigations; Mechanically fastened joints; Adhesively bonded joints; Moisture permeation in epoxy graphite composites.

Dark currents through anthracene crystals with silver paste electrodes were studied as functions of temperature, applied voltage, and time. Activation energies between 0.5eV and 2.9eV were measured, there being a definite correlation between log sigma(0) and E (the compensation effect). However, it was shown that the compensation effect arises from the calculation of sigma(0) and E, and not from a true linear free-energy relationship. As simple carrier generation mechanisms were inadequate to explain the temperature-dependence results, a model involving transitions between two limiting mechanisms was invoked and developed. The voltage-dependence results are shown to arise by a transition from SCL currents at low voltages, to barrier-limited currents (BLC) at higher fields, where the Schottky effect controls the current-voltage response. Vindication of the choice of this model is obtained from the calculated values of the parameters epsilon, the permittivity of anthracene; A, the Richardson constant; phi, the surface energy barrier for hole injection from silver paste into anthracene; and W(E)(Ag), the work function for silver paste electrodes. (Author)

Photogeneration of free carriers in anthracene single crystals with strongly absorbed light has been studied under ultra-high vacuum (UHV) conditions. Single crystals of zone-refined synthetic anthracene were mounted in a modified sandwich cell set-up (2) in the UHV system. The generation mechanisms for both electrons and holes were found to depend markedly on the extent of evaporation of the crystal. This removal of the surface layers reduced the amount of singlet exciton dissociation at the surface, allowing the exciton-exciton collision generation mechanism to predominate. (Author)

The objective of the study was to determine the feasibility of new technical concepts inherent in the design of F sub 1, F sub 1 repeaters. This technical report covers two novel versions of small F sub 1, F sub 1 radio repeaters designed for use with FM tactical transceivers. Both developmental models are linear, single frequency repeaters (F sub 1, F sub 1), one is high gain (50 db); the other wide-band (500 kHz). The design of these repeaters utilizes the concepts of hybrid isolation and precise antenna matching. The results indicate that true F sub 1, F sub 1 radio repeaters are feasible. Included are detailed discussions of: F sub 1, F sub 1 repeater concept; antenna matching and broadbanding techniques; hybrid isolation; amplifier and filter development; tests and evaluation; miniaturization; future trends and goals., Sponsored in part by the DARPA.

[Please check date of thesis]

Antep, Data tomada do prefacio