Absence of reptation in highly confined polymers

We present results of mechanical stress relaxation measurements on polymers confined at the air-water interface in the form of a monolayer. Systematic measurements allow, to our knowledge, for the first time, observation of the scaling of the stress relaxation time of the highly confined polymers as a function of both surface concentration and molecular weight. The observed scaling is found to be very close to that expected for motion of unentangled polymer solutions with hydrodynamic interactions. Our experimental observations thus clearly rule out the possibility of entanglement and hence reptation as a mode of relaxation in such highly confined polymeric systems.

Selecting replacements for invasive plants to support frugivores in highly modified sites: a case study focusing on Lantana camara

Invasive plants are regarded as a major threat to biodiversity worldwide. Yet, in some cases, invasive plants now perform important ecological functions. For example, fleshy-fruited invasive plants provide food that supports indigenous frugivore populations. How can the disparate goals of conservation versus invasive weed control be managed? We suggest using the fruit characteristics of the invasive plant to select replacement indigenous plants that are functionally similar from the perspective of frugivores. These could provide replacement food resources at sites where plants with these characteristics are part of the goal plant community and where such plants would not otherwise regenerate. Replacement plants could also redirect seed dispersal processes to favour indigenous, rather than invasive, plant species. We investigated the utility of this approach by ranking all indigenous fleshy-fruited plant species from a region using a simple model that scored species based upon measures of fruit phenology, morphology, conspicuousness and accessibility relative to a target invasive species, Lantana (Lantana camara). The model successfully produced high scores for indigenous plant species that were used by more of the frugivores of Lantana than a random selection of plants, suggesting that this approach warrants further investigation.

Sustainable and profitable grazing management in a highly variable environment-evidence and insights from a long term grazing trial in northern Australia.

Rainfall variability is a major challenge to sustainable management in semi-arid rangelands. We present empirical evidence from a large, long-term grazing trial in northern Australia on the relative performance of constant heavy stocking, moderate stocking at long-term carrying capacity and variable stocking in coping with climate variability over a range of rainfall years. Moderate stocking gave good economic returns, maintained pasture condition and minimised soil loss and runoff. Heavy stocking was neither sustainable nor profitable in the long term. Variable stocking generally performed well but suffered economic loss and some decline in pasture condition in the transition from good to poor years. Importantly, our results show that sustainable and profitable management are compatible in semi-arid rangelands.

Highly Enhanced Thermopower in Two-Dimensional Electron Systems at Millikelvin Temperatures

We report experimental observation of an unexpectedly large thermopower in mesoscopic two-dimensional (2D) electron systems in GaAs/AlGaA heterostructures at sub-Kelvin temperatures and zero magnetic field. Unlike conventional nonmagnetic high-mobility 2D systems, the thermopower in our devices increases with decreasing temperature below 0.3 K, reaching values in excess of 100 mu V/K, thus exceeding the free electron estimate by more than 2 orders of magnitude. With support from a parallel study of the local density of states, we suggest such a phenomenon to be linked to intrinsic localized states and many-body spin correlations in the system.

Characterization of highly informative cross-species microsatellite panels for the Australian dugong (Dugong dugon) and Florida manatee (Trichechus manatus latirostris) including five novel primers

The Australian dugong (Dugong dugon) and Florida manatee (Trichechus manatus latirostris) are threatened species of aquatic mammals in the order Sirenia. Sirenian conservation and management actions would benefit from a more complete understanding of genetic diversity and population structure. Generally, species-specific microsatellite markers are employed in conservation genetic studies; however, robust markers can be difficult and costly to isolate. To increase the number of available markers, dugong and manatee microsatellite primers were evaluated for cross-species amplification. Furthermore, one manatee and four dugong novel primers are reported. After polymerase chain reaction optimization, 23 (92%) manatee primers successfully amplified dugong DNA, of which 11 (48%) were polymorphic. Of the 32 dugong primers tested, 27 (84%) yielded product in the manatee, of which 17 (63%) were polymorphic. Dugong and manatee primers were compared and the most informative markers were selected to create robust and informative marker-panels for each species. These cross-species microsatellite marker-panels can be employed to assess other sirenian populations and can provide beneficial information for the protection and management of these unique mammals.

Hundreds of variants clustered in genomic loci and biological pathways affect human height

Most common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence the phenotype. Genome-wide association (GWA) studies have identified more than 600 variants associated with human traits, but these typically explain small fractions of phenotypic variation, raising questions about the use of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait. The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P = 0.016) and that underlie skeletal growth defects (P < 0.001). Second, the likely causal gene is often located near the most strongly associated variant: in 13 of 21 loci containing a known skeletal growth gene, that gene was closest to the associated variant. Third, at least 19 loci have multiple independently associated variants, suggesting that allelic heterogeneity is a frequent feature of polygenic traits, that comprehensive explorations of already-discovered loci should discover additional variants and that an appreciable fraction of associated loci may have been identified. Fourth, associated variants are enriched for likely functional effects on genes, being over-represented among variants that alter amino-acid structure of proteins and expression levels of nearby genes. Our data explain approximately 10% of the phenotypic variation in height, and we estimate that unidentified common variants of similar effect sizes would increase this figure to approximately 16% of phenotypic variation (approximately 20% of heritable variation). Although additional approaches are needed to dissect the genetic architecture of polygenic human traits fully, our findings indicate that GWA studies can identify large numbers of loci that implicate biologically relevant genes and pathways.

Genetic Heterogeneity in Autism Spectrum Disorders in a Population Isolate

Positional cloning has enabled hypothesis-free, genome-wide scans for genetic factors contributing to disorders or traits. Traditionally linkage analysis has been used to identify regions of interest, followed by meticulous fine mapping and candidate gene screening using association methods and finally sequencing of regions of interest. More recently, genome-wide association analysis has enabled a more direct approach to identify specific genetic variants explaining a part of the variance of the phenotype of interest. Autism spectrum disorders (ASDs) are a group of childhood onset neuropsychiatric disorders with shared core symptoms but varying severity. Although a strong genetic component has been established in ASDs, genetic susceptibility factors have largely eluded characterization. Here, we have utilized modern molecular genetic methods combined with the advantages provided by the special population structure in Finland to identify genetic risk factors for ASDs. The results of this study show that numerous genetic risk factors exist for ASDs even within a population isolate. Stratification based on clinical phenotype resulted in encouraging results, as previously identified linkage to 3p14-p24 was replicated in an independent family set of families with Asperger syndrome, but no other ASDs. Fine-mapping of the previously identified linkage peak for ASDs at 3q25-q27 revealed association between autism and a subunit of the 5-hydroxytryptamine receptor 3C (HTR3C). We also used dense, genome-wide single nucleotide polymorphism (SNP) data to characterize the population structure of Finns. We observed significant population substructure which correlates with the known history of multiple consecutive bottle-necks experienced by the Finnish population. We used this information to ascertain a genetically homogenous subset of autism families to identify possible rare, enriched risk variants using genome-wide SNP data. No rare enriched genetic risk factors were identified in this dataset, although a subset of families could be genealogically linked to form two extended pedigrees. The lack of founder mutations in this isolated population suggests that the majority of genetic risk factors are rare, de novo mutations unique to individual nuclear families. The results of this study are consistent with others in the field. The underlying genetic architecture for this group of disorders appears highly heterogeneous, with common variants accounting for only a subset of genetic risk. The majority of identified risk factors have turned out to be exceedingly rare, and only explain a subset of the genetic risk in the general population in spite of their high penetrance within individual families. The results of this study, together with other results obtained in this field, indicate that family specific linkage, homozygosity mapping and resequencing efforts are needed to identify these rare genetic risk factors.

New reagents 3: aluminium iodide - a highly regioselective ether-cleaving reagent with novel cleavage pattern

AlI3 is an easily accessible and versatile ether-cleaving reagent.

Free Range Hens Use the Range More When the Outdoor Environment Is Enriched.

To evaluate the role of using forage, shade and shelterbelts in attracting birds into the range, three trials were undertaken with free range layers both on a research facility and on commercial farms. Each of the trials on the free range research facility in South Australia used a total of 120 laying hens (Hyline Brown). Birds were housed in an eco-shelter which had 6 internal pens of equal size with a free range area adjoining the shelter. The on-farm trials were undertaken on commercial free range layer farms in the Darling Downs in Southeast Queensland with bird numbers on farms ranging from 2,000-6,800 hens. The first research trial examined the role of shaded areas in the range; the second trial examined the role of forage and the third trial examined the influence of shelterbelts in the range. These treatments were compared to a free range area with no enrichment. Aggressive feather pecking was only observed on a few occasions in all of the trials due to the low bird numbers housed. Enriching the free range environment attracted more birds into the range. Shaded areas were used by 18% of the hens with a tendency (p = 0.07) for more hens to be in the paddock. When forage was provided in paddocks more control birds (55%) were observed in the range in morning than in the afternoon (30%) while for the forage treatments 45% of the birds were in the range both during the morning and afternoon. When shelterbelts were provided there was a significantly (p<0.05) higher % of birds in the range (43% vs. 24%) and greater numbers of birds were observed in areas further away from the poultry house. The results from the on-farm trials mirrored the research trials. Overall 3 times more hens used the shaded areas than the non shaded areas, with slightly more using the shade in the morning than in the afternoon. As the environmental temperature increased the number of birds using the outdoor shade also increased. Overall 17 times more hens used the shelterbelt areas than the control areas, with slightly more using the shelterbelts in the afternoon than in the morning. Approximately 17 times more birds used the forage areas compared to the control area in the corresponding range. There were 8 times more birds using a hay bale enriched area compared to the area with no hay bales. The use of forage sources (including hay bales) were the most successful method on-farm to attract birds into the range followed by shelterbelts and artificial shade. Free range egg farmers are encouraged to provide pasture, shaded areas and shelterbelts to attract birds into the free range.

Personality, health and lifestyle in a questionnaire family study: A comparison between highly cooperative and less cooperative families

The effect of nonresponse on health and lifestyle measures has received extensive study, showing at most relatively modest effects. Nonresponse bias with respect to personality has been less thoroughly investigated. The present study uses data from responding individuals as a proxy for the missing data of their nonresponding family members to examine the presence of nonresponse bias for personality traits and disorders as well as health and lifestyle traits. We looked at the Big Five personality traits, borderline personality disorder (BPD) features, attention-deficit/hyperactivity disorder, Anger, and several measures of health (Body Mass Index, migraine) and lifestyle (smoking, alcohol use). In general, outcomes tend to be slightly more favorable for individuals from highly cooperative families compared to individuals from less cooperative families. The only significant difference was found for BPD features (p = .001). However, the absolute difference in mean scores is very small, less than 1 point for a scale ranging from 0 to 72. In conclusion, survey data on personality, health and lifestyle are relatively unbiased with respect to nonresponse.

A highly effective and selective male lure for Bactrocera jarvisi (Tryon) (Diptera: Tephritidae)

Bactrocera jarvisi (Tryon) is a moderate pest fruit fly particularly in northern Australia where mango is its main commercial host. It was largely considered non-responsive to the known male lures. However, male B. jarvisi are attracted to the flowers of Bulbophyllum baileyi, Passiflora ligularis, Passiflora maliformis and Semecarpus australiensis and this paper describes an attempt to determine the attractive compounds in the latter two species through chemical analysis. At about the same time, zingerone was identified as a fruit fly attractant in the flowers of Bulbophyllum patens in Malaysia, and this led the author to speculate that it could be attracting B. jarvisi to the flowers of B. baileyi. Two long-term traps, each with lures containing 2 g of liquefied zingerone and 1 mL maldison EC were established at Speewah, west of Cairns, in November 2001 and retained until April 2007. Over five complete years, 68 897 flies were captured, of which 99.6% were male B. jarvisi. Annual peaks in activity occurred between mid-January and early February, when they averaged 1428.5 +/- 695.6 (mean +/- standard error) male B. jarvisi/trap/week. Very few B. jarvisi were caught between June and September. Among 12 other species of Bactrocera and Dacus attracted to zingerone were the previously non-lure responsive Bactrocera aglaiae, a new species Bactrocera speewahensis, and the rarely trapped Dacus secamoneae. Four separate trials were conducted over 8- to 19-week periods to compare the numbers and species of Bactrocera and Dacus caught by zingerone, raspberry ketone/cue-lure or methyl eugenol-baited traps. Overall, 27 different species of Bactrocera and Dacus were recorded. The zingerone-baited traps caught 97.799.3% male B. jarvisi and no methyl eugenol responsive flies. Significantly more Bactrocera neohumeralis or Bactrocera tryoni were attracted to raspberry ketone/cue-lure than to zingerone (P < 0.001). Zingerone and structurally related compounds should be tested more widely throughout the region.

Phosphorus in agricultural soils of Finland - characterization of reserves and retention in mineral soil profiles

An overwhelming majority of all the research on soil phosphorus (P) has been carried out with soil samples taken from the surface soils only, and our understanding of the forms and the reactions of P at a soil profile scale is based on few observations. In Finland, the interest in studying the P in complete soil profiles has been particularly small because of the lack of tradition in studying soil genesis, morphology, or classification. In this thesis, the P reserves and the retention of orthophosphate phosphorus (PO4-P) were examined in four cultivated mineral soil profiles in Finland (three Inceptisols and one Spodosol). The soils were classified according to the U.S. Soil Taxonomy and soil samples were taken from the genetic horizons in the profiles. The samples were analyzed for total P concentration, Chang and Jackson P fractions, P sorption properties, concentrations of water-extractable P, and for concentrations of oxalate-extractable Al and Fe. Theoretical P sorption capacities and degrees of P saturation were calculated with the data from the oxalate-extractions and the P fractionations. The studied profiles can be divided into sections with clearly differing P characteristics by their master horizons Ap, B and C. The C (or transitional BC) horizons below an approximate depth of 70 cm were dominated by, assumingly apatitic, H2SO4-soluble P. The concentration of total P in the C horizons ranged from 729 to 810 mg kg-1. In the B horizons between the depths of 30 and 70 cm, a significant part of the primary acid-soluble P has been weathered and transformed to secondary P forms. A mean weathering rate of the primary P in the soils was estimated to vary between 230 and 290 g ha-1 year-1. The degrees of P saturation in the B and C horizons were smaller than 7%, and the solubility of PO4-P was negligible. The P conditions in the Ap horizons differed drastically from those in the subsurface horizons. The high concentrations of total P (689-1870 mg kg-1) in the Ap horizons are most likely attributable to long-term cultivation with positive P balances. A significant proportion of the P in the Ap horizons occurred in the NH4F- and NaOH-extractable forms and as organic P. These three P pools, together with the concentrations of oxalate-extractable Al and Fe, seem to control the dynamics of PO4-P in the soils. The degrees of P saturation in the Ap horizons were greater (8-36%) than in the subsurface horizons. This was also reflected in the sorption experiments: Only the Ap horizons were able to maintain elevated PO4-P concentrations in the solution phase − all the subsoil horizons acted as sinks for PO4-P. Most of the available sorption capacity in the soils is located in the B horizons. The results suggest that this capacity could be utilized in reducing the losses of soluble P from excessively fertilized soils by mixing highly sorptive material from the B horizons with the P-enriched surface soil. The drastic differences in the P characteristics observed between adjoining horizons have to be taken into consideration when conducting soil sampling. Sampling of subsoils has to be made according to the genetic horizons or at small depth increments. Otherwise, contrasting materials are likely to be mixed in the same sample; and the results of such samples are not representative of any material present in the studied profile. Air-drying of soil samples was found to alter the results of the sorption experiments and the water extractions. This indicates that the studies on the most labile P forms in soil should be carried out with moist samples.

Reduced fungicide use on a new Australian peanut cultivar, highly resistant to the late leaf spot and rust pathogens

Rust (caused by Puccinia arachidis) and late leaf spot (LLS, caused by Mycosphaerella berkeleyi) can cause significant yield losses in Australian peanut crops. Until recently, all commercial peanut varieties were highly susceptible to these pathogens, but the new Australian cultivar Sutherland has significantly higher levels of resistance than the older cultivars. Field trials were conducted at two sites in Queensland to (a) confirm the improved resistance of cv. Sutherland over another commercial cultivar, Menzies, (b) study the effects of timing of first spray, spray interval and cultivar on disease severity and yield, and (c) develop a suitable fungicide management program for cv. Sutherland. In the 2006 and 2007 trials, rust and LLS developed slower and had lower final disease ratings and AUDPC values on unsprayed plots of cv. Sutherland than on cv. Menzies. The timing of the first spray is critical in managing both rust and late leaf spot, with the results demonstrating that the first fungicide spray on cv. Sutherland should be applied as soon as rust and LLS are first seen on cv. Menzies. In most trials spray intervals of 14 days or 21 days were suitable to effectively control rust and LLS. In years with low disease pressure, few, if any, fungicide applications will be needed to manage the diseases, but in other years up to four sprays may be necessary. © Australasian Plant Pathology Society Inc. 2012.

Relaminarization in highly accelerated turbulent boundary layers

The mean flow development in an initially turbulent boundary layer subjected to a large favourable pressure gradient beginning at a point x0 is examined through analyses expected a priori to be valid on either side of relaminarization. The ‘quasi-laminar’ flow in the later stages of reversion, where the Reynolds stresses have by definition no significant effect on the mean flow, is described by an asymptotic theory constructed for large values of a pressure-gradient parameter Λ, scaled on a characteristic Reynolds stress gradient. The limiting flow consists of an inner laminar boundary layer and a matching inviscid (but rotational) outer layer. There is consequently no entrainment to lowest order in Λ−1, and the boundary layer thins down to conserve outer vorticity. In fact, the predictions of the theory for the common measures of boundary-layer thickness are in excellent agreement with experimental results, almost all the way from x0. On the other hand the development of wall parameters like the skin friction suggests the presence of a short bubble-shaped reverse-transitional region on the wall, where neither turbulent nor quasi-laminar calculations are valid. The random velocity fluctuations inherited from the original turbulence decay with distance, in the inner layer, according to inverse-power laws characteristic of quasi-steady perturbations on a laminar flow. In the outer layer, there is evidence that the dominant physical mechanism is a rapid distortion of the turbulence, with viscous and inertia forces playing a secondary role. All the observations available suggest that final retransition to turbulence quickly follows the onset of instability in the inner layer.It is concluded that reversion in highly accelerated flows is essentially due to domination of pressure forces over the slowly responding Reynolds stresses in an originally turbulent flow, accompanied by the generation of a new laminar boundary layer stabilized by the favourable pressure gradient.