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The Philippine archipelago is tectonically complex and seismically hazardous, yet few seismic hazard assessments have provided national coverage. This article presents an updated probabilistic seismic hazard analysis for the nation. Active shallow crustal seismicity is modeled by faults and gridded point sources accounting for spatially variable occurrence rates. Subduction interfaces are modeled with faults of complex geometry. Intraslab seismicity is modeled by ruptures confined to the slab volume. Source geometries and earthquake rates are derived from seismicity catalogs, geophysical data sets, and historic-to-paleoseismic constraints on fault slip rates. The ground motion characterization includes models designed for global use, with partial constraint by residual analysis. Shallow crustal faulting near metropolitan Manila, Davao, and Cebu dominates shaking hazard. In a few places, peak ground acceleration with 10% probability of exceedance in 50 years on rock reaches 1.0 g. The results of this study may have utility for defining the design base shear in the National Structural Code of the Philippines.

A kākāpō (A computed tomography (CT) examination revealed a full-thickness circular defect in the central cranium with suspected herniation of brain and dura. Surgery was performed at 37 days of age, and the herniated dura was dissected from the open fontanelle. Attempts to reduce the herniated tissue were unsuccessful, so the herniated dura and cortex were clamped and resected. The dura was closed and the periosteum of the skull was scarified and monofilament polypropylene mesh was secured tautly over the fontanelle. The mesh graft was infused with autologous bone marrow harvested from the ulna in an attempt to stimulate osteogenesis in the mesh repair. The skin flap was then closed. Post-operative recovery and healing were without complication. A CT examination 4 weeks after surgery showed no recurrence of the hernia, and a composite of mesh and scar over the open fontanelle which had reduced in diameter. The chick was released back onto an off-shore island with a radio transmitter and it continues to be monitored regularly.The tissue resected at surgery consisted of a cylindrical core of cerebral parenchyma overlain by a mildly hyperplastic epidermis, and large amounts of oedematous fibrovascular tissue arising from the leptomeninges.Rostral parietal meningoencephalocoele.This is the first report of successful surgical resolution of a meningoencephalocoele in any bird. Techniques from human neurosurgery were adapted for the unique anatomical features of the avian skull. The risks of the procedure included increased intra-cranial pressure resulting in anaesthetic complications or death, cerebrospinal fluid leakage, meningitis or recurrence of the meningoencephalocoele. In the longer term, there was a risk of developmental deficits in cognition or behaviour. None of these complications eventuated in the short to medium term, probably due to the small size of the meningoencephalocoele.

Summary The southern Pacific Islands region is highly seismically active, and includes earthquakes from four major subduction systems, seafloor fracture zones and transform faults, and other sources of crustal seismicity. Since 1900, the area has experienced >350 earthquakes of M > 7.0, including 11 of M ≥ 8.0. Given the elevated threat of earthquakes, several probabilistic seismic hazard analyses have been published for this region or encompassed subregions; however, those that are publicly accessible do not provide complete coverage of the region using homogeneous methodologies. Here, we present a probabilistic seismic hazard model for the southern Pacific Islands that comprehensively covers the Solomon Islands in the northwest to the Tonga islands in the southeast. The seismic source model accounts for active shallow crustal seismicity with seafloor faults and gridded smoothed seismicity, subduction interfaces using faults with geometries defined based on geophysical datasets and models, and intraslab seismicity modelled by a set of ruptures that occupy the slab volume. Each source type is assigned occurrence rates based on sub-catalogues classified to each respective tectonic context. Subduction interface and crustal fault occurrence rates also incorporate a tectonic component based on their respective characteristic earthquakes. We demonstrate the use of non-standard magnitude-frequency distributions to reproduce the observed occurrence rates. For subduction interface sources, we use various versions of the source model to account for epistemic uncertainty in factors impacting the maximum magnitude earthquake permissible by each source, varying the interface lower depth and segmentation as well as the magnitude scaling relationship used to compute the maximum magnitude earthquake and subsequently its occurrence rate. The ground motion characterisation uses a logic tree that weights three ground motion prediction equations for each tectonic region. We compute hazard maps for 10% and 2% probability of exceedance in 50 years on rock sites, discussing the regional distribution of peak ground acceleration and spectral acceleration with a period of 1.0 s, honing in on the hazard curves and uniform hazard spectra of several capital or populous cities and drawing comparisons to other recent hazard models. The results reveal that the most hazardous landmasses are the island chains closest to subduction trenches, as well as localised areas with high rates of seismicity occurring in active shallow crust. We use seismic hazard disaggregation to demonstrate that at selected cities located above subduction zones, the PGA with 10% probability of exceedance in 50 years is controlled by Mw > 7.0 subduction interface and intraslab earthquakes, while at cities far from subduction zones, Mw

For life insurers in the United Kingdom (UK), the risk margin is one of the most controversial aspects of the Solvency II regime which came into force in 2016. The risk margin is the difference between the technical provisions and the best estimate liabilities. The technical provisions are intended to be market-consistent, and so are defined as the amount required to be paid to transfer the business to another undertaking. In practice, the technical provisions cannot be directly calculated, and so the risk margin must be determined using a proxy method; the method chosen for Solvency II is known as the cost-of-capital method. Following the implementation of Solvency II, the risk margin came under considerable criticism for being too large and too sensitive to interest rate movements. These criticisms are particularly valid for annuity business in the UK – such business is of great significance to the system for retirement provision. A further criticism is that mitigation of the impact of the risk margin has led to an increase in reinsurance of longevity risks, particularly to overseas reinsurers. This criticism has led to political interest, and the risk margin was a major element of the Treasury Committee inquiry into EU Insurance Regulation. The working party was set up in response to this criticism. Our brief is to consider both the overall purpose of the risk margin for life insurers and solutions to the current problems, having regard to the possibility of post-Brexit flexibility. We have concluded that a risk margin in some form is necessary, although its size depends on the level of security desired, and so is primarily a political question. We have reviewed possible alternatives to the current risk margin, both within the existing cost-of-capital methodology and considering a wide range of alternatives. We believe that requirements for the risk margin will depend on future circumstances, in particular relating to Brexit, and we have identified a number of possible changes to methodology which should be considered, depending on circumstances.

In December 2018, at the conclusion of its second implementation phase, the Global Earthquake Model (GEM) Foundation released its first version of a map outlining the spatial distribution of seismic hazard at a global scale. The map is the result of an extensive, joint effort combining the results obtained from a collection of probabilistic seismic hazard models, called the GEM Mosaic. Together, the map and the underlying database of models provide an up-to-date view of the earthquake threat globally. In addition, using the Mosaic, a synopsis of the current state-of-practice in modeling probabilistic seismic hazard at national and regional scales is possible. The process adopted for the compilation of the Mosaic adhered to the maximum extent possible to GEM’s principles of collaboration, inclusiveness, transparency, and reproducibility. For each region, priority was given to seismic hazard models either developed by well-recognized national agencies or by large collaborative projects involving local scientists. The version of the GEM Mosaic presented herein contains 30 probabilistic seismic hazard models, 14 of which represent national or sub-national models; the remainder are regional-scale models. We discuss the general qualities of these models, the underlying framework of the database, and the outlook for the Mosaic’s utility and its future versions.

Determining wire and wire bundle amperage capacity (i.e., “ampacity”) currently relies on the use of standards to derate wire ampacity when in a bundle configuration. The feasibility of developing physics-based and regression thermal models of single wires and wire bundles to determine ampacity using a customized test apparatus was investigated during a pathfinder study. A test facility was developed and various wire and wire bundle articles were tested under a variety of temperature and pressure conditions using an efficient test matrix formulated using Design of Experiments (DOE) techniques. Physics-based models were developed and correlated to the test results. Regression models were formulated and compared to test results and standards.

The family Nodaviridae includes two genera, Alphanodavirus and Betanodavirus. The family name derives from the Japanese village of Nodamura where Nodamura virus was first isolated from Culex tritaeniorhynchus mosquitoes. Virions are non-enveloped and spherical in shape with icosahedral symmetry (T=3) and diameters ranging from 25 to 33 nm. The genome consists of two molecules of single-stranded positive-sense RNA: RNA1 and RNA2. The virion capsid consists of 180 protein subunits arranged on a T=3 surface lattice. Alphanodaviruses infect insects, whereas betanodaviruses are pathogens of fish. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Nodaviridae, which is available at www.ictv.global/report/nodaviridae.

The family Sarthroviridae includes a single genus, Macronovirus, which in turn includes a single species, Macrobrachium satellite virus 1. Members of this species, named extra small virus, are satellite viruses of Macrobrachium rosenbergii nodavirus, an unclassified virus related to members of the family Nodaviridae. Both viruses have isometric, spherical virions, infect giant freshwater prawns and together cause white tail disease, which is responsible for mass mortalities and severe economic losses in hatcheries and farms. Infection is caused by both vertical and horizontal transmission of virus. Aquatic insects act as a carrier to transmit the disease in prawns. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Sarthroviridae, which is available at www.ictv.global/report/sarthroviridae.

This study explored the pathways of ingress of Acidovorax citrulli, the causal agent of bacterial fruit blotch of cucurbits, into watermelon seeds. Up until 7 days post-inoculation (DPI), a significantly higher percentage of watermelon seeds was infected with A. citrulli when the bacteria were applied (c. 1 × 106 colony-forming units) to stigmas versus ovary pericarps of female flowers. Immunofluorescence microscopy showed that, with stigma inoculation, A. citrulli colonized style and ovary tissues by 1 DPI, and the bacteria co-localized with pollen germ tubes in these tissues. With ovary pericarp inoculation, A. citrulli cells penetrated the epicarp and mesocarp tissues by 1 DPI but did not reach endocarp until 4 DPI. Finally, manual pollination followed by stigma inoculation led to >53% A. citrulli-infected seed lots, while A. citrulli was not detected in seeds/ovules generated by stigma inoculation without pollination (chemically induced parthenocarpy). These results show that stigma inoculation results in faster colonization of watermelon ovules by A. citrulli than pericarp inoculation, even though there is no difference in the levels of infection in mature seeds. The data also indicate that pollen germ tubes play an important role in A. citrulli ingress into watermelon seeds via stigmas.

We investigate the optical properties of proton-implanted photonic crystal (PhC) vertical-cavity surface-emitting lasers (VCSELs) emitting in the visible spectrum. The fabricated lasers have a threshold current of 1.3 mA and single-mode output power greater than 1 mW at room temperature. The incorporation of a PhC into the top facet of a proton-implanted VCSEL results in a stable single-fundamental-mode operation with a side-mode suppression ratio larger than 30 dB and a constant beam divergence independent of injection current level or ambient temperature. Using an index-step optical fiber model, we compare the effects of different hole etching depths to variations in output beam divergence. By varying the design and etching depth of the hole pattern, the lasers can either be optimized for low beam divergence or low threshold currents. The controllable refractive index guidance effect from the PhC allows for precise engineering of the optical properties of these visible VCSELs for consumer and imaging applications.

Johnson, K. L., Minsavage, G. V., Le, T., Jones, J. B., and Walcott, R. R. 2011. Efficacy of a nonpathogenic Acidovorax citrulli strain as a biocontrol seed treatment for bacterial fruit blotch of cucurbits. Plant Dis. 95:697-704. Bacterial fruit blotch (BFB), caused by the seedborne, gram-negative bacterium Acidovorax citrulli, is a serious threat to cucurbit seed and fruit production worldwide. Because of the lack of effective management strategies, we investigated the efficacy of a nonpathogenic A. citrulli strain as a biological control seed treatment for BFB. For this study, we generated a type III secretion system mutant of A. citrulli, AAC00-1ΔhrcC, that was nonpathogenic on watermelon but retained its ability to colonize germinating watermelon seed. With watermelon seed naturally infested with A. citrulli, AAC00-1ΔhrcC reduced BFB seedling transmission by 81.8% relative to control seed. In comparison, another A. citrulli antagonist, A. avenae strain AAA 99-2, reduced BFB seedling transmission by 74.6% for seed samples from the same lot. Additionally, when female watermelon blossoms were protected with AAC00-1ΔhrcC and subsequently challenged with AAC00-1, the resulting seedlots displayed 8% BFB seedling transmission. This was not significantly different than seed from blossoms protected with AAA 99-2 (4%) but significantly less than those from blossoms protected with 0.1 M phosphate-buffered saline (36%). These results suggest that nonpathogenic A. citrulli has potential as a biological control seed treatment component in a comprehensive BFB management program. Bacterial fruit blotch (BFB) of cucurbits, caused by the gramnegative bacterium Acidovorax citrulli (33) (formerly A. avenae subsp. citrulli; 42), poses a significant threat to cucurbit seed and fruit production worldwide (32). BFB was reported in commercial watermelon fields in Florida in 1989, and frequent outbreaks caused significant economic losses across the southeastern United States in the early 1990s (35). At present, the disease is a sporadic threat to cucurbit producers worldwide (4,26,29), because an outbreak can lead to 100% yield loss under ideal environmental conditions.

The two coupled optical cavities within a vertical-cavity surface-emitting laser have the unique ability to modulate the spatial distribution of the longitudinal optical mode, without changing the total photon density in the laser cavities, by simultaneously directly modulating the two optical cavities exactly out-of-phase. A rate-equation analysis predicts that this condition, which we term push-pull modulation, exhibits a superior modulation response than that of conventional direct modulation. The push-pull modulation can enable high-speed operation with low power consumption, as a large modulation bandwidth can be achieved independent of the total photon density and/or the injection dc current. Experimental evidence of spatially changing the longitudinal mode is presented, and push-pull modulation at 2.5 Gb/s is demonstrated for the first time.

Converging lines of evidence implicate the beta-amyloid peptide (Ass) as causative in Alzheimer's disease. We describe a novel class of compounds that reduce A beta production by functionally inhibiting gamma-secretase, the activity responsible for the carboxy-terminal cleavage required for A beta production. These molecules are active in both 293 HEK cells and neuronal cultures, and exert their effect upon A beta production without affecting protein secretion, most notably in the secreted forms of the amyloid precursor protein (APP). Oral administration of one of these compounds, N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester, to mice transgenic for human APP(V717F) reduces brain levels of Ass in a dose-dependent manner within 3 h. These studies represent the first demonstration of a reduction of brain A beta in vivo. Development of such novel functional gamma-secretase inhibitors will enable a clinical examination of the A beta hypothesis that Ass peptide drives the neuropathology observed in Alzheimer's disease.

This paper reports an experimental and theoretical investigation of the indentation of a layered elastic solid, with special reference to the surface force apparatus (SFA). The contacting surfaces of the SFA comprise a 3-layer material: a thin mica surface layer on a thicker epoxy layer supported by a thick silica substrate. An existing finite element analysis of the deformation of ideal mica/epoxy/silica surfaces used in the SFA is adapted to compare with the experimental measurements of the variation of contact size with load, both with and without adhesion at the interface. This is in marked difference to the Johnson, Kendall and Roberts (JKR) theory for homogeneous solids. Experiments and finite element calculations were also carried out on the elastic indentation of a thin (5.5??m) layer of mica on a very thick layer of epoxy (>100??m). As input data for the calculations, the elastic moduli of the mica and epoxy were measured in separate indentation experiments. The stiffness of a layered solid can be expressed by an 'effective modulus' , which has been deduced from the experimental measurements and compared with the theoretical values with fair success. The work of adhesion is commonly measured in the SFA by observing the 'pull-off force' to separate the surfaces. The theory shows that, for a layered solid, the pull-force can vary significantly from the JKR value for a homogeneous solid. In particular, it was found that the mica surface energy, ?sv, measured by SFA experiments using crossed cylinders of mean radius R, where the materials are layered and the mica/mica adhesion is high, can vary with the pull-off force Fp according to Fp/4?R < ?sv < Fp/2?R, and for this particular experiment was given as ?sv = Fp/3.5 ?R as compared with ?sv = Fp/3?R for homogeneous materials.

Everolimus is an immunosuppressant drug that was approved for prophylactic use in the United States to prevent organ rejection in adult kidney and liver transplant recipients. Therapeutic drug management (TDM) is required to optimize the dose for efficacy and to minimize toxicity. Prior to the development of immunoassay reagents for everolimus, laboratory developed chromatographic methods were routinely used to support TDM for everolimus testing. However, the use of high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS)for everolimus TDM is not widely utilized in hospitals or transplant centers due to either a lack of mass spectrometry instrumentation or resources for assay development. An everolimus reagent kit and method was developed by Waters Corporation for use on the Waters ACQUITY TQD mass spectrometer system.The purpose for this study was to evaluate the investigational use only (IUO) Waters MassTrak Immunosuppressants XE (IUO) kit on a Waters ACQUITY(®) ultra performance liquid chromatography (UPLC) coupled to an ACQUITY(®) TQD mass spectrometer and to compare this test system to a laboratory developed mass spectrometry assay for everolimus.We evaluated precision and performed a patient comparison study on 56 renal transplant patients that received everolimus against a validated in house HPLC-MS/MS method.5-day precision was performed on two patient pooled samples and analyzed in triplicate. Total imprecision for the low patient pool (3.77 ng/mL) and high patient pool (10.87 ng/mL) was15 %CV. Deming regression analysis was performed for the patient comparison and the linear regression equation was y=0.973x+0.03, Sy/x 0.55, and the correlation coefficient was 0.9815.The Waters MassTrak Immunosuppressants XE (IUO) kit and method had good correlation between the concentration range of 3-15 ng/mL to the established in-house HPLC-MS/MS method.

Effective partnerships among government, industry and community actors are increasingly being identified as crucial to the effectiveness of natural resource management activities both in Australia and overseas. Three types of partnerships are identified from the literature and discussed. This paper describes the nature of partnerships affecting land use allocation in Queensland's sugar industry, based on a case study of the Herbert River District in north Queensland. By reviewing relevant government and industry documents, the process of sugar cane land allocation, and the role of non-industry officials in that process, it is suggested that substantial scope for improvement exists.

JKR theory describes how surface energy modifies the Hertz theory of contact between elastic solids, giving rise to a larger contact area for positive loads, and to a finite tensile load 1.5πRΔγ in order to separate the solids. Here the original theory for circular contacts is extended to the general elliptical Hertzian contact. To a good approximation, the contact area remains elliptical, but the eccentricity varies continuously with the load, and at pull-off is substantially less than the Hertzian value.

As length scales decrease, adhesive forces become increasingly important. These adhesive forces contribute to the normal load in experiments conducted on thin layered systems using micro-probe instruments such as the surface force apparatus (SFA) and the atomic force microscope (AFM). Adhesion between these thin-layer systems was analysed by Sridhar et al (1997 J. Phys. D: Appl. Phys. 30 1710) for the SFA geometry and Johnson and Sridhar (2001 J. Phys. D: Appl. Phys. 34 683) for AFM using a numerical SJF (Sridhar–Johnson–Fleck) version of the JKR (Johnson–Kendal–Roberts) theory. In this paper, adhesion mechanics between a compliant elastic coating and a spherical probe is investigated using the SJF model in detail. When the substrate is rigid, the non-dimensional pull-off force may differ from the JKR value of −0.5 by as much as 90%. Computations of the contact size at zero load and pull-off force are presented for a range of values of adhesion energy. Finally, empirical relations for the contact load and contact compliance as a function of contact radius were obtained from the numerical data for practical layer-substrate material systems.

In the calendering process a tape or sheet of deformable material passes through the nip between hard cylindrical rollers. Usually the rolls are driven at the same peripheral speed, but small differences in speed, often referred to as 'creep', can occur if one of the rolls is externally driven and the other is driven by the friction in the contact. In these circumstances it has been observed that a tape that enters the nip adhering to the driven (slower) surface may transfer at exit to the driving (faster) surface but not the other way round. The mechanics of this transfer process is examined theoretically and experimentally in this paper for the case of double sided adhesive tape. It is argued that on emerging from the nip the tape will separate from the surface at which the shear strain in the adhesive is greater and that for transfer to occur the contact load must be sufficient to cause plastic extension of the tape.

H2-M or HLA-DM are non-classical class II molecules encoded by the MHC and play an important role during antigen presentation. They catalyze exchange of CLIP (Class II-associated invariant chain peptide) or other low-affinity peptides bound to class II molecules for peptides capable of more efficient binding. The phenotype of mice lacking H2-M is determined by the allotype of the MHC class II molecules expressed. In general, H2-M deficiency does not affect the surface expression of mature class II molecules. The class II molecules in such cases predominantly contain CLIP in their peptide-binding groove. In some mice strains, H2-M deficiency results in defective CD4+ T-cell development accompanied by defective responses to conventional antigens and superantigens. Even though the HLA class II molecules show similar dependency for HLA-DM for presenting antigens in vitro, their interaction in vivo is not known. By using transgenic approach we show here that DQ8 and DR3 are expressed at normal levels in H2-M-deficient mice and the CD4+ T-cell development is unaltered. However, the ability of DQ8 molecules to present peptide antigens is compromised in a H2-M-deficient state. Presentation of exogenous bacterial superantigens by both DQ8 and DR3 is unaffected in H2-M-deficient mice. Unexpectedly, Staphylococcal Enterotoxin B-induced systemic IFN-gamma production was significantly higher in H2-M-deficient DQ8/DR3 transgenic mice and these mice were susceptible to SEB-induced toxic shock at doses that are non-lethal to H2-M-sufficient counterparts.

The Johnson, Kendall and Roberts (JKR) adhesion theory is frequently applied to study the adhesion mechanics of thin compliant layers coated on to glass substrate in an atomic force microscope (AFM). These compliant layers are subjected to micro indentation in the AFM using a flat or spherical indenter. But, JKR theory is based on the contact of homogeneous, isotropic solids. The finite element analysis used by Sridhar et al (1997) (J. Phys. D: Appl. Phys. 30 1710-19) to study the adhesion mechanics of the three-layered crossed-cylinder arrangement of the surface force apparatus (SFA) has been extended to this AFM geometry. The effect of indenter elasticity is included for both spherical and flat punch probes. Computations of contact size and contact compliance each as a function of load are presented for a range of values of adhesion energy and elastic modulus ratio of layer and substrate.

Natural and synthetic steroid estrogens have been detected in sewage treatment work effluents discharged into rivers. An understanding of the partitioning of these estrogens between water and sediment is critical for the prediction of their fates in river systems. Hence, a series of experiments was conducted to ascertain the effects of differing environmental conditions on estrogen partitioning to sediment. Fugacity level 1 (sediment phase) output data demonstrated a good correlation with removal of estrogens from the water phase. Synthetic estrogens, with their higher Kow values, were removed more readily from the water phase than the natural estrogens. Maximum sorption to the sediment phase was attained after 1 h of shaking. At higher estrogen concentrations, there was a decrease in estrogen removal, while higher levels of sediment induced greater removal. The sorption of estrogen to sediments correlated with total organic carbon content. However, the presence of organic carbon was not a prerequisite fo...

Implementing the concept of sustainability through integrated approaches to natural resource management poses enormous challenges for both the rural communities and government agencies concerned. This paper reviews the underlying rhetoric of sustainable agricultural systems and the integrated resource management paradigm and identifies some of the challenges being experienced in translating this rhetoric into practice. A relatively recently implemented community-based integrated catchment management (ICM) process in a rural community in northeast Australia is examined in terms of some of the lessons learned that may be relevant to other similar integrated resource management (IRM) processes. It reveals a pragmatic, opportunistic, and evolving implementation process based on adaptive learning rather than a more traditional rational planning approach. Some essential characteristics of a community-based IRM process are identified, including fostering communication; providing a structure that fosters cooperation and facilities coordination among community, industry, and government agencies; the integration of IRM principles into local government planning schemes; and an emergent strategic approach to IRM program implementation. The authors conclude by identifying some essential characteristics of an IRM process that can assist a community to adapt to, and manage change for, sustainable resource use.

There has been considerable recent concern over the amount of vegetation clearance in the wet tropics of northern Australia. This paper reports on the results of a case study undertaken in the lower Herbert River catchment in north-east Queensland, which utilised remote sensing and Geographic Information Systems (GIS) to assess both spatial and temporal changes in land cover since European settlement in the mid-nineteenth century. We demonstrate that since European settlement there has been a substantial reduction in the area of Melaleuca, rainforest, and eucalyptus-dominated land-cover patterns. We also provide a range of quantitative measures to show that the landscape diversity, integrity and quality of these ecosystems have also declined between the 1860s and 1996. We conclude that reform is required at policy, planning and enterprise levels if the ecological, economic and social values of these systems are to be maintained in the future.

Fundamental studies of the mechanics and physics of dry sliding friction between solid surfaces have been impeded in the past by surface roughness and the difficulty of determining the real area of contact. The last decade has seen an explosive development of techniques to study friction at single-asperity contacts in which the real and apparent contact areas coincide. The contribution of these developments to interpreting dry friction is discussed in this paper. Experiments with smooth compliant rubber led to an appreciation of the role of adhesive forces and to including its effects in contact mechanics. Atomically smooth surfaces are obtained in the surface force apparatus (SFA) through the property of mica to cleave on atomic planes, and in the atomic force/friction microscope (AFM) by the use of nanometre size contacts on single crystals. Based on friction measurements in the SFA and AFM, a hypothesis is advanced that sliding of atomically smooth contacts takes place by the nucleation and propagation of dislocation-like defects through the interface. An analysis by Hurtado and Kim [29] using dislocation mechanics suggests a ‘scale effect’ in which friction is governed by resistance to nucleation in very small contacts and by resistance to propagation in larger contacts.

Because coral reefs are sensitive to land derived inputs of nutrient and sediment, there is concern worldwide for the effects of anthropogenic change in river catchments on reefs. Thirty-one river catchments drain directly into the waters of the Great Barrier Reef, NE Australia. This case study was undertaken on the floodplain of the Herbert River catchment in north Queensland, utilizing remote sensing and GIS to assess both spatial and temporal changes in freshwater wetlands and riparian forests. We demonstrate that there has been a very large reduction in the area of these ecosystems since European settlement in the mid nineteenth century, with an 80% decline in their extent since 1943. We provide a range of quantitative measures to show that the landscape diversity of these ecosystems has also declined. These changes are of importance in terms of regional, national and international trends. We argue that policy, planning and management reform is required if the remaining ecological, economic and social values of these systems and the adjacent Great Barrier Reef Marine Park are to be maintained.

BACKGROUND: Neuromuscular blocking agents are used in critically ill patients to induce therapeutic paralysis. These drugs leave patients fully immobile but conscious. Analgesics and sedatives are concomitantly administered with the paralytic agents. Little is known about what patients remember when they receive these combinations of drugs. Even less is known about the experiences and needs of the patients' family members during the patients' paralysis. OBJECTIVES: To obtain recollections of therapeutic paralysis in critically ill adult trauma patients and to determine the psychological, emotional, and educational needs of the patients' family members during the time the patients were paralyzed. METHODS: A qualitative phenomenological approach was used to investigate the "lived" experience of therapeutic paralysis of 11 pairs of subjects. Each pair consisted of one critically ill adult trauma patient and one member of the patient's family. RESULTS: The patients recalled their experience of therapeutic paralysis with vagueness, as if they had been dreaming. Few recalled pain or painful procedures. Patients remembered having nurses and family members provide emotional support and encouragement. Family members understood the rationale for use of the drugs. They remembered being encouraged to touch and talk with patients. The subjects suggested providing additional education about events that occur when paralysis is being reversed. CONCLUSIONS: Two confounding variables may have affected these findings: a liberalized visiting policy and use of effective pain and sedation protocols. Healthcare professionals and patients' family members should monitor bedside conversations and use touch and words of encouragement to support patients during therapeutic paralysis.

The problem of how contact between elastic spheres is modified by the surface forces which act between them is becoming of great interest with the possibility of studying such contacts experimentally in the atomic force microscope and in the surface force apparatus. Experiments are frequently interpreted with the help of the JKR adhesion theory, in which the action of the surface forces is represented by the change in surface energy involved in uniting or separating the two surfaces. This has two drawbacks: it is strictly valid only when the Tabor parameter is large, though in fact it appears that the condition is sufficient, and it gives no help with the attractive forces before contact takes place, which may cause `jumping on'. However, it has one enormous virtue: the results are described by simple algebraic equations, which all can manipulate as required. In contrast, full numerical analyses, such as the pioneering solution by Muller, Derjaguin and Toporov and a more recent solution by Greenwood, give only the results the authors choose to pass on. These establish when the JKR solution is valid and indicate the ways in which it is incomplete; but stop there. For this reason, an analytical solution by Maugis using a simplified force-separation law, that the adhesive stress has a fixed value whenever the separation is less than a critical distance, has proved most valuable. However, it too has a drawback, though a minor one: the shape of the gap involves elliptical integrals, which is inconvenient when the extension to visco-elastic spheres is considered. Here we present an alternative to the Maugis theory, based on the combination of two Hertzian pressure distributions. The results are very close to those of the Maugis model, but the gap shape now involves only elementary functions.

The energy fluxes upon shrinkage of the contact area are calculated for a pair of spheres in adhesion. Various notions of energy release rate are introduced and analyzed for correlating the external work parameters and the work of adhesion. Decomposition of the energy release rate into reversible and irreversible parts shows that the reversible part is the work of adhesion and it can be described by the cohesive response purely at the contact zone-edge. This result justifies the use of local zone-edge quantities for modeling the interaction of adhesion and friction. For specific quantitative analysis, adhesion is represented by the Dugdale model, uniform cohesive traction up to a limited separation, as an approximation to more exact inter-surface forces. Exact results are given for the entirely reversible energy release rate to the edge of the contact and the energy release rate to the cohesive zone. The latter is named the strain energy release rate and found to depend on the path in loading parameter space, while the reversible energy release rate is independent of the loading path. The solution for shear of the contact is given as well. Energy released reversibly to be converted into surface energy is identified in contrast to energy released due to slip which will be partially or totally dissipated as heat. The relevance of the results for friction is discussed and contrasted with their significance for the mixed mode fracture of a circular joint.

Measurements of atomic friction in the atomic force microscope frequently show periodic variations at the lattice spacing of the surface being scanned, which have the saw‐tooth wave form characteristic of “stick–slip” motion. Simple models of this behaviour have been proposed, in which the “dynamic element” of the system is provided by the elastic stiffness and inertia of the cantilever which supports the tip of the microscope, in its lateral, i.e., torsional mode of vibration. These models have been successful in predicting the observed motion, but only by assuming that the cantilever is heavily damped. However, the source of this damping in a highly elastic cantilever is not explained. To resolve the paradox, it is shown in this note that it is necessary to introduce the elastic stiffness of the contact into the model. The relationship between the contact stiffness, the cantilever stiffness and the amplitude of the periodic friction force is derived in order for stick–slip motion at lattice spacing to be achieved.

The Australian sugar industry is largely confined to the narrow, high rainfall coastal zone in which competition from tourist and recreational uses, urban encroachment, public utilities and hobby farms for natural resources has increased significantly in recent years and is likely to grow in the future. This paper briefly examines the socio-political, economic and environmental context in which natural resources are currently managed in the Australian sugar industry. We argue that planning, in concert with a range of policy and economic instruments, can play an important role in the resolution of such problems. Building on the collective national and international experience of other industries, options for efficient and equitable allocation of resources between the sugar industry and its neighbours at the policy level and on-farm are outlined and discussed.

The surface force apparatus (SFA) comprises thin molecularly smooth mica sheets glued to glass cylinders, which are pressed into contact with their axes at right angles. It is frequently used, in conjunction with the Johnson - Kendall - Roberts (JKR) adhesion theory, to extract the surface energy of the contacting sheets. This procedure is open to possible error since the JKR theory is based on the contact of homogeneous, isotropic elastic cylinders. This paper extends the JKR theory to the layered structure of the SFA. Two approaches have been followed: (i) direct calculations for prescribed values of the layer thickness and elastic moduli; (ii) an experimental calibration procedure for an existing apparatus.

Observations on the Vancouver mass transit system suggest that noise, vibration and corrugation of the rail appear to be associated with close conformity between the transverse profiles of the wheel and rail. To investigate this, a dynamic model of the wheel and rail under conditions of close conformity has been developed. Previous work has suggested that motion of the wheel could be neglected, so the model comprises two subsystems: (a) the rail and its supports, and (b) the contact between wheel and rail. A dynamic model of a continuously supported rail is presented, which is consistent with similar models in the literature. Conformal contact has been represented in two ways: (a) as a single highly eccentric elliptical contact, and (b) as a two-point contact. Novel ‘rolling contact mechanics’ have been incorporated in both these models. The complete system is closed: oscillations of the rail give rise to fluctuating contact forces, which in turn excite the rail. A linear stability analysis of the system shows it to be stable under all conditions examined, thus precluding the possibility of self-excited oscillations occurring on a perfectly smooth rail. The model can then be used to investigate the forced response to existing roughness on the railhead, which is the subject of a companion paper (1).

Decision making in natural resource management is characterised by complex decisions based on incomplete data. Furthermore, the structure of the decision-making process tends to be unstable, being highly context specific. Investment in specific and tightly focused decision support systems in this context may often not be justified. A prototype software toolkit. NRM Tools, designed to provide flexible decision support in this context, the use of which can evolve as tasks and understanding evolve, is described. The defining feature of NRM Tools is that it is designed to allow decision makers in natural resource management to develop new decision support tools to address new tasks through recombination of existing data resources and analytical tools (models and inference engines for example). This is achieved through the use of a task language comprising a set of primitives (functions for data access, analysis and presentation) and a set of control structures for combination of those primitives.

Fundamental studies of friction between solid surfaces are bedevilled by their inevitable roughness. However recent developments in nanotribology through molecular dynamics, the surface force apparatus, and the atomic force microscope have made possible direct examination of adhesion and friction at a single asperity in which the real and apparent contact areas coincide. In this paper the continuum theories of straight adhesion at a spherically tipped asperity are reviewed and a “map” presented which indicates the conditions under which the different theories apply. The interaction between friction and adhesion is then considered from the point of view of “fracture mechanics”. This approach has the advantage of clearly separating the roles of continuum mechanics and physics. The former is used to calculate the “elastic energy release rate” G as the adhesion is broken; the work of adhesion Gc can only be found from physical considerations.

Many researchers have observed metallic wear debris in the form of very thin platelets. In particular Akagaki & Kato (1987) revealed how such debris can be formed by progressive plastic extrusion from the edges of the irregularities on the softer of two sliding surfaces. This behaviour has been reproduced in experiments reported here, in which a single soft asperity is modelled by a blunt copper wedge in sliding contact with a flat hard steel surface under conditions of boundary lubrication. This progressive extrusion with continuous sliding is attributed to ‘plastic ratchetting’ and two ways in which the process can be driven have been identified: (i) pummelling of the soft surface by the asperities of the hard surface and (ii) cyclic stressing of the soft surface by the stress concentrations which occur at the edges of a hard slider. The kinematical shakedown theorem from the theory of plasticity is used to determine the asperity contact pressure necessary to drive these ratchetting processes. A significant feature of this mechanism is that it can occur under frictionless conditions.

Blood pressure has a diurnal pattern primarily related to activity and sleep. Chronic renal failure patients may lack the normal nocturnal decline in blood pressure during sleep. In 33 subjects (14 with normal renal function and 19 with renal dysfunction), the relationship between depth of daytime sleep, as determined by electroencephalographic sleep phase, and change in mean arterial blood pressure (MAP) and heart rate measured oscillometrically, was correlated. In 15 chronic renal failure patients, the effect of daytime and nighttime sleep on MAP and heart rate was compared. The percent change in night asleep versus day awake MAP and heart rate was measured (with Space Labs ambulatory blood pressure monitors) and compared with the percent change in daytime sleep-related MAP and heart rate measured during a daytime sleep electroencephalographic study. During daytime sleep, MAP changes are not significantly different in the normal versus renal dysfunction groups. In the 33 study subjects, MAP declines progressively from the upright position to Phase 3/4 sleep (118 +/- 3.6 to 106 +/- 3.6 mm Hg). The largest decline occurs between the upright to recumbent position, before sleep. Heart rate declines moving from the upright to recumbent position, 76 +/- 2.3 to 70 +/- 2.1 beats/min, but does not decline further with sleep. In 15 chronic renal failure patients, heart rate (10.8 +/- 2.8%; P0.05), but not MAP, declines during nighttime sleep. Both MAP (7.7 +/- 3.3%) and heart rate (5.4 +/- 1.9%) decline significantly during daytime sleep. The responses of MAP and heart rate to daytime and nighttime sleep were in opposite directions in 3 of 15 subjects.(ABSTRACT TRUNCATED AT 250 WORDS)