Agricultural intensification and loss of matrix habitat over 23 years in the West Wimmera, south-eastern Australia

The global trend toward more intensive forms of agriculture is changing the nature of matrix habitat in agricultural areas. Removal of components of matrix habitat can affect native biota at the paddock and the landscape scale, particularly where intensification occurs over large areas. We identify the loss of paddock trees due to the proliferation of centre pivot irrigation in dryland farming areas as a potentially serious threat to the remnant biota of these areas. We used a region of south-eastern Australia as a case study to quantify land use change from grazing and dryland cropping to centre pivot irrigation over a 23-year period. We also estimated rates of paddock tree loss in 5 representative landscapes within the region over the same period. The total area affected by centre pivots increased from 0 ha in 1980 to nearly 9000 ha by 2005. Pivots were more likely to be established in areas which had originally been plains savannah and woodlands containing buloke (Allocasuarina luehmannii), a food source for an endangered bird. On average, 42% of paddock buloke trees present in 1982 were lost by 2005. In the two landscapes containing several centre pivots, the loss was 54% and 70%. This accelerated loss of important components of matrix habitat is likely to result in species declines and local extinctions. We recommend that measures to alleviate the likely negative impacts of matrix habitat loss on native biota be considered as part of regional planning strategies.

Impact of tobacco tax reforms on tobacco prices and tobacco use in Australia

OBJECTIVE: To document the impact of changes to tobacco taxes on the range and price of tobacco sold during the period when the National Tobacco Campaign (NTC) was run.

DATA SOURCES: Information about brand availability, pack size, and price was extracted from Australian Retail Tobacconist. A retail observational survey was undertaken to monitor actual retail prices. Data on cigarette prices, brands, packet configurations, and outlets from which they were purchased were obtained from the benchmark and three follow up population telephone surveys conducted to evaluate the NTC.

METHOD: Data from the three sources were compared to see the extent to which the impact of tax changes had been offset by greater retail discounting and a more concerted effort by consumers to purchase cheaper products.

RESULTS: Smokers were unable to cushion themselves from the sharp price increases that occurred during the third phase of the NTC. Both average recommended retail prices of manufactured cigarettes and average actual cigarette prices paid by smokers increased by 25% in real prices.

CONCLUSION: The fall in smoking prevalence over the first two phases of the NTC was substantially greater than would be expected due to tax changes alone. The fall in smoking consumption over the first two phases was slightly less than would be expected and in the third considerably higher than would be expected.

High-performance composite from epoxy and glass fibers : morphology, mechanical, dynamic mechanical, and thermal analysis

Diglycidyl ether of bisphenol-A type epoxy resin cured with diamino diphenyl sulfone was used as the matrix for fiber-reinforced composites to get improved mechanical and thermal properties for the resulting composites. E-glass fiber was used for fiber reinforcement. The morphology, tensile, flexural, impact, dynamic mechanical, and thermal properties of the composites were analyzed. The tensile, flexural, and impact properties showed dramatic improvement with the addition of glass fibers. Dynamic mechanical analysis was performed to obtain the Tg of the cured matrix as well as the composites. The improved thermal stability of the composites was clear from the thermogravimetric analysis. Scanning electron micrographs were taken to understand the interfacial adhesion between the fiber and the matrix. The values of mechanical properties were compared with modified epoxy resin composite system. Predictive models were applied using various equations to compare the mechanical data obtained theoretically and experimentally.

Transient responses of a wetting film to mechanical and electrical perturbations

This article reports real-time observations and detailed modeling of the transient response of thin aqueous films bounded by a deformable surface to external mechanical and electrical perturbations. Such films, tens to hundreds of nanometers thick, are confined between a molecularly smooth mica plate and a deformable mercury/electrolyte interface on a protuberant drop at a sealed capillary tube. When the mercury is negatively charged, the water forms a wetting film on mica, stabilized by electrical double layer forces. Mechanical perturbations are produced by driving the mica plate toward or by retracting the mica plate from the mercury surface. Electrical perturbations are applied to change the electrical double layer interaction between the mica and the mercury by imposing a step change of the bias voltage between the mercury and the bulk electrolyte. A theoretical model has been developed that can account for these observations quantitatively. Comparison between experiments and theory indicates that a no-slip hydrodynamic boundary condition holds at the molecularly smooth mica/electrolyte surface and at the deformable mercury/electrolyte interface. An analysis of the transient response based on the model elucidates the complex interplay between disjoining pressure, hydrodynamic forces, and surface deformations. This study also provides insight into the mechanism and process of droplet coalescence and reveals a novel, counterintuitive mechanism that can lead to film instability and collapse when an attempt is made to thicken the film by pulling the bounding mercury and mica phases apart.

Influences of agricultural landuse and seasonal changes in abiotic conditions on invertebrate colonisation of riparian leaf detritus in intermittent streams

The structure and function of agricultural stream reaches with sparse riparian and floodplain vegetation differ from those of forested reaches, but may be ‘reset’ as these streams flow through reaches with forested riparian zones. We investigated whether invertebrate colonisation of River Red Gum (Eucalyptus camaldulensis) leaf packs in lowland intermittent streams was influenced by the adjacent reach-scale landuse (cleared farmland or forested reserve) within an agricultural catchment in Victoria, Australia. Further, we examined the influence of seasonal changes in hydrology and associated changes in abiotic conditions on the colonisation of leaves by repeating experiments over two summers and one spring. Across these experiments, there were no consistent differences in the structure of communities that colonised leaves in farmland and reserve reaches. In both seasons, most leaf colonists were collectors and few were shredders in both farmland and reserve reaches. Relative abundances of gastropod grazers were much higher in summer than in spring. The structure of invertebrate communities colonising leaves in the different reaches converged over time when streams flowed in spring, but diverged over time as the streams dried and abiotic conditions within disconnected pools became increasingly harsh in summer. Thus, patterns of leaf pack colonisation were influenced by the regional climate causing large seasonal changes in hydrology, but not by reach-scale landuse. The large-scale disturbances of agricultural landuse across the catchment and a supra-seasonal drought probably contributed to low diversities of invertebrate communities in the streams.

Factors influencing insulin resistance in relation to atherogenicity in mood disorders, the metabolic syndrome and tobacco use disorder

OBJECTIVE: This study examines the effects of malondialdehyde (MDA) and uric acid on insulin resistance and atherogenicity in subjects with and without mood disorders, the metabolic syndrome (MetS) and tobacco use disorder (TUD). METHODS: We included 314 subjects with depression and bipolar depression, with and without the MetS and TUD and computed insulin resistance using the updated homeostasis model assessment (HOMA2IR) and atherogenicity using the atherogenic index of plasma (AIP), that is log10 (triglycerides/high density lipoprotein (HDL) cholesterol. RESULTS: HOMA2IR is correlated with body mass index (BMI) and uric acid levels, but not with mood disorders and TUD, while the AIP is positively associated with BMI, mood disorders, TUD, uric acid, MDA and male sex. Uric acid is positively associated with insulin and triglycerides and negatively with HDL cholesterol. MDA is positively associated with triglyceride levels. Comorbid mood disorders and TUD further increase AIP but not insulin resistance. Glucose is positively associated with increasing age, male gender and BMI. DISCUSSION: The results show that mood disorders, TUD and BMI together with elevated levels of uric acid and MDA independently contribute to increased atherogenic potential, while BMI and uric acid are risk factors for insulin resistance. The findings show that mood disorders and TUD are closely related to an increased atherogenic potential but not to insulin resistance or the MetS. Increased uric acid is a highly significant risk factor for insulin resistance and increased atherogenic potential. MDA, a marker of lipid peroxidation, further contributes to different aspects of the atherogenic potential. Mood disorders and TUD increase triglyceride levels, lower HDL cholesterol and are strongly associated with the atherogenic, but not insulin resistance, component of the MetS.

Microstructures, mechanical and corrosion properties and biocompatibility of as extruded Mg-Mn-Zn-Nd alloys for biomedical applications

Extruded Mg-1Mn-2Zn-xNd alloys (x=0.5, 1.0, 1.5 mass %) have been developed for their potential use as biomaterials. The extrusion on the alloys was performed at temperature of 623K with an extrusion ratio of 14.7 under an average extrusion speed of 4mm/s. The microstructure, mechanical property, corrosion behavior and biocompatibility of the extruded Mg-Mn-Zn-Nd alloys have been investigated in this study. The microstructure was examined using X-ray diffraction analysis and optical microscopy. The mechanical properties were determined from uniaxial tensile and compressive tests. The corrosion behavior was investigated using electrochemical measurement. The biocompatibility was evaluated using osteoblast-like SaOS2 cells. The experimental results indicate that all extruded Mg-1Mn-2Zn-xNd alloys are composed of both α phase of Mg and a compound of Mg7Zn3 with very fine microstructures, and show good ductility and much higher mechanical strength than that of cast pure Mg and natural bone. The tensile strength and elongation of the extruded alloys increase with an increase in neodymium content. Their compressive strength does not change significantly with an increase in neodymium content. The extruded alloys show good biocompatibility and much higher corrosion resistance than that of cast pure Mg. The extruded Mg-1Mn-2Zn-1.0Nd alloy shows a great potential for biomedical applications due to the combination of enhanced mechanical properties, high corrosion resistance and good biocompatibility.

Tuning the mechanical and morphological properties of self-assembled peptide hydrogels via control over the gelation mechanism through regulation of ionic strength and the rate of pH change

Hydrogels formed by the self-assembly of peptides are promising biomaterials. The bioactive and biocompatible molecule Fmoc-FRGDF has been shown to be an efficient hydrogelator via a π-β self-assembly mechanism. Herein, we show that the mechanical properties and morphology of Fmoc-FRGDF hydrogels can be effectively and easily manipulated by tuning both the final ionic strength and the rate of pH change. The increase of ionic strength, and consequent increase in rate of gelation and stiffness, does not interfere with the underlying π-β assembly of this Fmoc-protected peptide. However, by tuning the changing rate of the system's pH through the use of glucono-δ-lactone to form a hydrogel, as opposed to the previously reported HCl methodology, the morphology (nano- and microscale) of the scaffold can be manipulated.

The principle of legality and contemporanea exposition est optima et fortissima in lege

If the principle of legality operates to obscure from Parliament the common law (rights) backdrop against which it legislates, the clarity or rights-sensitivity of that legislation cannot be improved. This undercuts, rather than promotes, the democratic and rule of law values that underpin the modern conception of the principle and its contemporary normative justification. So the courts must strive to give Parliament the clearest possible picture as to the content of the fundamental common law rights it seeks to protect and, depending on the right, freedom, or principle in legislative play, the strength with which the principle will be applied in order to do so. Parliament (and parliamentary counsel) can only ‘squarely confront’ those fundamental rights the existence and content of which was known at the time of legislating. The proposition which, necessarily, follows is that the rule of contemporanea exposition est optima et fortissimo in lege must be revived when judges apply the principle of legality to the construction of statutes. If the courts are to maintain and take seriously the normative justification for the principle then its application to the construction of statutes can only operate to protect from legislative encroachment those fundamental rights existing at the time the statute was enacted.

Preformed and sprayable polymeric mulch film to improve agricultural water use efficiency

Plastic mulch films are widely used in agriculture to enhance crop production by suppressing weeds, conserving soil water and increasing soil temperature. The majority of plastic mulch films are however not biodegradable and are typically removed after each growing season. Recovery of these plastics from the soil is difficult and can affect successive crop yields while causing substantive cost to the environment and farmers. Due to increasingly stringent regulations regarding use of non-degradable plastic in agriculture they are likely to be phased out in the near future. In the past 10 years several classes of 'biodegradable' materials have been studied but most of these films are reported to be relatively weak in mechanical properties, not efficiently degradable and cost prohibitive.More recently, researchers have turned their attention to sprayable biodegradable polymer coatings for use on soils due to their easy application and versatility. The ability to mix natural additives, plasticizers and fillers to control and improve the mechanical and biodegradation properties of the core polymeric mulch film has been the driving force behind the development of these next generation sprayable polymeric mulch films.There have been many excellent review articles and papers written about polymeric mulch film, but the developing sprayable polymer systems have not been reviewed to the same extent. This paper focusses on the research progress in the area of biodegradable and sprayable polymer mulch film with emphasis on polymer formulations, properties and application. It also discusses current research to highlight the importance, potential benefits and future challenges in developing a cost effective biodegradable sprayable film for use in production agriculture.

Mechanical properties and energy absorption of ceramic particulate and resin-impregnation reinforced aluminium foams

The mechanical properties of aluminium foams can be improved by matrix reinforcement and resin-impregnation methods. In the present study, aluminium foams were reinforced by both ceramic particulate reinforcing of the aluminium matrix and resin-impregnating pores. The mechanical properties and the energy absorption of the reinforced aluminium foams were investigated by dynamic and quasi-static compression. Results indicated that the ceramic particle additions of CBN, SiC and B4C in aluminium foams increase the peak stress, elastic modulus and energy absorption of the aluminium foams, under both conditions of dynamic and quasi-static compression. Moreover, the aluminium foams with and without ceramic particle additions exhibited obvious strain rate sensitivity during dynamic compression. Furthermore, the resin-impregnation improves the mechanic properties and energy absorption of aluminium foams significantly. However, aluminium foams with resin-impregnation showed negligible strain rate sensitivity under dynamic compression. It is reported that both the ceramic particle addition and resin-impregnation can be effective techniques to improve the mechanical and the energy absorption properties of aluminium foams.