bluuebunny/crossref_metadata_2025 huggingface dataset:
Generation of generalized moist potential vorticity in a frictionless and moist adiabatic flow
Authors: Gao Shouting , Wang Xingrong , Zhou Yushu
Published: June 2004

The discontinuity of the latent heat term could occur in the thermodynamic equation in the transition area between the unsaturated and saturated air where the latent heat is released associated with the condensation in the saturated air whereas the latent heat is not released in the unsaturated air. To fix the discontinuity, the condensation probability function ()k (q and qs are specific humidity and saturated specific humidity respectively, k = 9) is introduced into the thermodynamic framework with ()kqs. The generalized moist potential vorticity (GMPV) is thus defined and its tendency equation is derived. The analysis shows that in a frictionless and moist adiabatic flow, the GMPV can be generated in the unsaturated air only and its generation rate is determined by the environmental moisture and its gradient.
Heliospheric energetic particle observations by the Cassini spacecraft: Correlation with 1 AU observations
Authors: Lario D. , Livi S. , Roelof E. C. , Decker R. B. , Krimigis S. M. , Dougherty M. K.
Published: June 2004

We present energetic particle measurements from the Low‐Energy Magnetospheric Measurement System (LEMMS) on board the Cassini spacecraft during its heliospheric cruise to Saturn. We cover 3 years (2000–2002) of data during the maximum of the solar cycle 23. Cassini's heliocentric radial distance ranged from 2.5 to 8.0 AU. Energetic particle intensity enhancements were associated with either sporadic intense solar energetic particle events, the effects produced by recurrent corotating interaction regions, or the arrival of transient interplanetary shocks. High‐energy (>25 MeV) ion intensity enhancements were exclusively associated with the prompt component of intense solar energetic particle events. The largest low‐energy (<1 MeV) ion and near‐relativistic (43–305 keV) electron intensities occurred at the passage of interplanetary shocks. We compare particle intensities measured during the major solar energetic particle events near Earth with those measured at Cassini. We find that in general, the most intense events were observed by both Cassini and near‐Earth spacecraft. However, the arrival of energetic particles at Cassini's larger heliocentric distance was modulated by the presence of magnetic field structures formed between the Sun and Cassini. We analyze the relative intensities of the particle events at Cassini in terms of the level of solar activity during the previous solar rotation. When a new injection of solar energetic particles occurs after a period of intense solar activity, it may produce a particle event at 1 AU but not at Cassini. Transient plasma flows generated by previous solar events can act as effective barriers to the propagation of energetic particles to Cassini. These structures cause delays in the expected arrival time of energetic particles at Cassini as well as an effective diminution of the prompt component of the solar energetic particle events at heliocentric distances from 2.5 to 8.0 AU.
Magnetic signatures of Jupiter's bow shock during the Cassini flyby
Authors: Achilleos N. , Dougherty Michele K. , Young D. T. , Crary F.
Published: June 2004

The bow shock crossings detected during the Cassini flyby of Jupiter occur at positions which imply that Jupiter's bow shock was relatively inflated during the early (before 2001, Day 3) and late (after 2001, Day 40) periods of the encounter. A variety of magnetic shock signatures are seen, corresponding to a wide range (15–75 degrees) in the angle θBN between the shock normal and the solar wind field. The time variability of this angle for the “forward” part of the shock (near the nose) is generally consistent with a shock surface similar to that derived by Slavin et al. [1985] from Voyager/Pioneer data. This implies a long‐term stability for the global shape of the Jovian bow shock. Fits of Slavin‐type models to the shock crossing locations indicate that the solar wind pressure varied by an order of magnitude during the early phase of the Cassini flyby (up to 2001, Day 18) and that the bow shock itself was consequently in a highly dynamic state. A preliminary comparison of Cassini magnetometer (MAG) data with solar wind measurements by the Cassini Plasma Spectrometer (CAPS) reveals that the relation between the shock stand‐off distance and the solar wind pressure during the Cassini flyby was similar to that during the Voyager/Pioneer encounters. This indicates that the intrinsic “compressibility” of the Jovian magnetosphere is also probably stable over long timescales. The change in magnetic field direction between solar wind and magnetosheath indicates that the Jovian bow shock is fast magnetosonic, as expected for the high solar wind Mach numbers (>10) at the location of Jupiter.
Electrical properties of fine‐grained olivine: Evidence for grain boundary transport
Authors: ten Grotenhuis Saskia M. , Drury Martyn R. , Peach Colin J. , Spiers Chris J.
Published: June 2004

To investigate the mechanisms responsible for electrical conduction and deduce the relation between grain size and conductivity, the electrical conductivity of synthetic polycrystalline forsterite, with grain sizes between 1.1 ± 0.4 and 4.7 ± 2.4 μm, was measured at temperatures up to 1470°C and at 0.1 MPa pressure. The complex impedance plots display one clear arc, indicating a single dominant conduction mechanism. Bulk conductivity is inversely proportional to the grain size of the different samples. This relation suggests that the electrical conductivity of the samples is controlled by grain boundary diffusion of the charge carriers. The apparent activation energy (Q) for diffusion of the charge carriers between 1180° and 1470°C lies between 315 ± 39 and 323 ± 15 kJ/mol. This resembles previous data on grain boundary diffusion of Mg in forsterite. A geometrical model of less‐conducting cubic grains and more‐conducting grain boundaries agrees well with the experimental data. This model is applied to predict the conductivity contrast between fine‐grained shear zones and less‐deformed regions in the lithosphere. Upper mantle shear zones are predicted to have 1.5–2 orders of magnitude higher conductivity than less‐deformed regions in the lithosphere. This means grain boundary transport probably has an important role in the existence of anomalously high conductivity zones in the upper mantle and that fine‐grained shear zones might be detected using magnetotelluric methods.
Fluxes and gas transfer rates of the biogenic trace gas DMS derived from atmospheric gradients
Authors: Zemmelink Hendrik J. , Dacey John W. H. , Hintsa Eric J. , McGillis Wade R. , Gieskes Winfried W. C. , Klaassen Wim , de Groot Henk W. , de Baar Hein J. W.
Published: June 2004

Gas transfer rates were determined from vertical profile measurements of atmospheric dimethylsulfide (DMS) gradients over the equatorial Pacific Ocean obtained during the GasEx‐2001 cruise. A quadratic relationship between gas transfer velocity and wind speed was derived from the DMS flux measurements; this relationship was in close agreement with a parameterization derived from relaxed eddy accumulation measurements of DMS over the northeastern Pacific Ocean. However, the GasEx‐2001 relationship results in gas transfer rates that are a factor 2 higher than gas transfer rates calculated from a parameterization that is based on coincident eddy correlation measurements of CO2 flux. The measurement precision of both the profiling and eddy correlation techniques applied during GasEx‐2001 is comparable; the two gas transfer data sets are in agreement within their uncertainty. Differences in the number of samples and the wind speed range over which CO2 and DMS fluxes were measured are likely causes for the observed discrepancy.
Seasonal patterns of gross primary production and ecosystem respiration in an alpine meadow ecosystem on the Qinghai‐Tibetan Plateau
Authors: Kato Tomomichi , Tang Yanhong , Gu Song , Hirota Mitsuru , Cui Xiaoyong , Du Mingyuan , Li Yingnian , Zhao Xinquan , Oikawa Takehisa
Published: June 2004

We measured the net ecosystem CO2 exchange (NEE) in an alpine meadow ecosystem (latitude 37°29′–45′N, longitude 101°12′–23′E, 3250 m above sea level) on the Qinghai‐Tibetan Plateau throughout 2002 by the eddy covariance method to examine the carbon dynamics and budget on this unique plateau. Diurnal changes in gross primary production (GPP) and ecosystem respiration (Re) showed that an afternoon increase of NEE was highly associated with an increase of Re. Seasonal changes in GPP corresponded well to changes in the leaf area index and daily photosynthetic photon flux density. The ratio of GPP/Re was high and reached about 2.0 during the peak growing season, which indicates that mainly autotrophic respiration controlled the carbon dynamics of the ecosystem. Seasonal changes in mean GPP and Re showed compensatory behavior as reported for temperate and Mediterranean ecosystems, but those of GPPmax and Remax were poorly synchronized. The alpine ecosystem exhibited lower GPP (575 g C m−2 y−1) than, but net ecosystem production (78.5 g C m−2 y−1) similar to, that of subalpine forest ecosystems. The results suggest that the alpine meadow behaved as a CO2 sink during the 1‐year measurement period but apparently sequestered a rather small amount of C in comparison with similar alpine ecosystems.
Vertical profiles of NO3, N2O5, O3, and NOx in the nocturnal boundary layer: 1. Observations during the Texas Air Quality Study 2000
Authors: Stutz Jochen , Alicke Björn , Ackermann Ralf , Geyer Andreas , White Allen , Williams Eric
Published: June 2004

Nocturnal chemistry in urban areas can considerably influence the composition of the boundary layer by removing nitrogen oxides and hydrocarbons, as well as changing the size and composition of aerosol particles. Although these processes can have a severe impact on pollution levels at night and during the following day, little quantitative information is available. In particular, the vertical variation of trace gas concentrations and chemistry at night has received little attention and is thus poorly understood. Here we present differential optical absorption spectroscopy (DOAS) measurements of the vertical distributions of O3, NO2, and NO3 during the Texas Air Quality Study 2000 near Houston, TX. Distinct vertical profiles, with lower mixing ratios of O3 and NO3 near the ground than above 100 m altitude, were observed. Mixing ratios of NO3 aloft reached 50 ppt and above, and steady state N2O5 levels were calculated to be 100–300 ppt. A one‐dimensional chemical transport model reveals that the formation of the vertical trace gas distributions is driven by deposition, surface emissions of NO, reactions of O3 and NO3, and vertical mixing. The removal of O3 in Houston is found to proceed by dry deposition, while NOx is primarily lost above 10 m altitude by N2O5 chemistry. The study shows that chemistry in polluted areas is strongly altitude dependent in the lowest 100 m of the nocturnal atmosphere. This altitude dependence should be considered in future field and model studies of urban air pollution.
Vertical profiles of NO3, N2O5, O3, and NOx in the nocturnal boundary layer: 2. Model studies on the altitude dependence of composition and chemistry
Authors: Geyer Andreas , Stutz Jochen
Published: June 2004

Recent field observations in urban areas have shown that trace gases, such as O3, NO2, and NO3, develop distinct vertical concentration profiles at night. Because nocturnal chemistry can change the gas‐phase and particulate composition in the urban boundary layer considerably, it is important to understand the mechanisms that lead to the change of trace gas levels with altitude. The quantification of the altitude dependence of chemical processes leading to the removal of volatile organic carbons (VOC) and NOx are crucial to assess the influence of nocturnal chemistry on ozone formation during the following day. We present a one‐dimensional chemical transport model developed to study the interaction between chemistry and vertical transport in the nocturnal boundary layer. The model reproduces the general features found in field observations, such as positive O3 and NO3 gradients. The slow upward transport of NO and VOC emitted near the ground and the simultaneously occurring chemistry, in particular the reactions of NO with O3 and NO3, are found to control the vertical structure of the chemistry of NOx, NO3, N2O5, and VOC. In the case of NO2 and O3, dry deposition is also significant. The model results show that vertical transport of N2O5 plays an important role, and is often the main source of NO3 radicals near the ground. Chemical steady state calculations of the concentrations of NO3 and N2O5, as they have been used in the past, are therefore not representative in cases with significant vertical fluxes of N2O5. The vertical gradient of the oxidation rate of NO2 implies that the removal of NOx occurs predominately in the upper nocturnal boundary layer (NBL). Our study shows that observations at one altitude and chemical box models are often insufficient to accurately describe the chemistry in NBL.
Interactions among topographically induced elastic stress, static fatigue, and valley incision
Authors: Molnar Peter
Published: June 2004

Gravity acting on topography creates differential stress, which, for sufficiently high, steep topography, can fracture intact bedrock. If static fatigue governed the time dependence of that fracturing, a feedback should exist between incision of the landscape and fracturing. The timescale for static fatigue decreases exponentially with differential stress. By creating deeper, steeper valleys, incision should increase the differential stress and, as a result, accelerate fracturing of intact rock. Because both fluvial systems and hillslopes can transport fractured rock much more easily than they can both erode intact rock and then transport its products, topographically induced fracturing could play a crucial role in landscape evolution, especially of steep terrain. Predicting differential stress useful for general rules in geomorphology, however, appears to be difficult, in part because the stress distribution depends sensitively on the precise form of the topography and, perhaps more importantly, because the differential stress for specific topography can differ not only in magnitude but also in sign for small differences in Poisson's ratio. Nevertheless, it appears possible that in steep terrain where rivers are capable of moving bed load sufficiently rapidly, the rate‐limiting process for incision might be static fatigue of the rock under stress due to gravity acting on the adjacent topography.
Nonlinear dynamics in flow through unsaturated fractured porous media: Status and perspectives
Authors: Faybishenko Boris
Published: June 2004

The need has long been recognized to improve predictions of flow and transport in partially saturated heterogeneous soils and fractured rock of the vadose zone for many practical applications, such as remediation of contaminated sites, nuclear waste disposal in geological formations, and climate predictions. Until recently, flow and transport processes in heterogeneous subsurface media with oscillating irregularities were assumed to be random and were not analyzed using methods of nonlinear dynamics. The goals of this paper are to review the theoretical concepts, present the results, and provide perspectives on investigations of flow and transport in unsaturated heterogeneous soils and fractured rock, using the methods of nonlinear dynamics and deterministic chaos. The results of laboratory and field investigations indicate that the nonlinear dynamics of flow and transport processes in unsaturated soils and fractured rocks arise from the dynamic feedback and competition between various nonlinear physical processes along with complex geometry of flow paths. Although direct measurements of variables characterizing the individual flow processes are not technically feasible, their cumulative effect can be characterized by analyzing time series data using the models and methods of nonlinear dynamics and chaos. Identifying flow through soil or rock as a nonlinear dynamical system is important for developing appropriate short‐ and long‐time predictive models, evaluating prediction uncertainty, assessing the spatial distribution of flow characteristics from time series data, and improving chemical transport simulations. Inferring the nature of flow processes through the methods of nonlinear dynamics could become widely used in different areas of the earth sciences.
Mesoscale gravity wave variances from AMSU‐A radiances
Authors: Wu Dong L.
Published: June 2004

A variance analysis technique is developed here to extract gravity wave (GW) induced temperature fluctuations from NOAA AMSU‐A (Advanced Microwave Sounding Unit‐A) radiance measurements. By carefully removing the instrument/measurement noise, the algorithm can produce reliable GW variances with the minimum detectable value as small as 0.1 K2. Preliminary analyses with AMSU‐A data show GW variance maps in the stratosphere have very similar distributions to those found with the UARS MLS (Upper Atmosphere Research Satellite Microwave Limb Sounder). However, the AMSU‐A offers better horizontal and temporal resolution for observing regional GW variability, such as activity over sub‐Antarctic islands.
The dynamic rupture process of the 2001 Geiyo, Japan, earthquake
Authors: Miyatake Takashi , Yagi Yuji , Yasuda Takumi
Published: June 2004

The 2001, Geiyo earthquake (Mw = 6.7) occurred as a normal fault event within the young subducting Philippine Sea plate. We investigate a dynamic rupture process of the earthquake and estimate the dynamic parameters. Firstly, the space‐time distribution of slip of the earthquake, i.e., the kinematic model, was investigated by inverting the near‐field strong ground motion data and teleseismic waveform data. Secondly, we reconstruct a dynamic model in constraint with the above kinematic model. The distribution of Dc is also estimated from the inverted slip rate time functions [Mikumo et al., 2003] and found to be less than 70 cm. We found that dynamic parameters are very heterogeneous. There exist two asperities. The peak stress drop on the first asperity is about 20 MPa, and 10 MPa on the second one. Very low or negative stress drop zone is found between two asperities. The strength excess, and fracture energy distribution are also heterogeneous.
Past rates of accumulation in central West Antarctica
Authors: Siegert Martin J. , Payne Antony J.
Published: June 2004

The spatial variation in ice accumulation is critical to the form and stability of ice sheets. In West Antarctica, knowledge of present ice accumulation rates is restricted to sparse measurements and interpolations across data free regions, while information on former ice accumulation is restricted to a small number of ice cores and numerical modeling results. Here, isochronous internal ice sheet layers, recorded by airborne radio‐echo sounding and dated at their stratigraphic position at the Byrd ice core site, are used to reconstruct the spatial pattern of accumulation across the main West Antarctic ice divide for the past 16,000 years. Mean accumulation calculated for the last 3100 years matches well to present‐day accumulation rates, which is compatible with previous observations on Siple Dome. Accumulation between 6400 and 16,000 years ago is calculated to be around half that at present, in accordance with recent ice sheet modeling results.
Loss of retinoblastoma but not p16 function allows bypass of replicative senescence in human fibroblasts
Authors: Wei Wenyi , Herbig Utz , Wei Shan , Dutriaux Annie , Sedivy John M
Published: June 2004

Current models envision replicative senescence to be under dual control by the p53 and retinoblastoma (RB) tumour‐suppressor pathways. The role of the p16INK4a–RB pathway is controversial, and the function of RB in human cells has not been tested directly. We used targeted homologous recombination to knock out one copy of RB in presenescent human fibroblasts. During entry into senescence, RB+/− cells underwent spontaneous loss of heterozygosity and the resultant RB−/− clones bypassed senescence. The extended lifespan phase was eventually terminated by a crisis‐like state. The same phenotype was documented for p21CIP1/WAF1 and p53 heterozygous cells, indicating that loss of function of all three genes results in failure to establish senescence. By contrast, the abolition of p16 function by the expression of a p16‐insensitive cyclin‐dependent kinase 4 protein or siRNA‐mediated knockdown provided only minimal lifespan extension that was terminated by senescence. We propose that p53, p21 and RB act in a linear genetic pathway to regulate cell entry into replicative senescence.
RNA sensors: novel regulators of gene expression
Authors: Kaempfer Raymond
Published: June 2004

RNA‐mediated control can evolve far more rapidly than mechanisms that rely on proteins, creating selective advantages in adaptive gene regulation. Recently, evidence has emerged that messenger RNA is a source of cis‐acting RNA elements that sense external signals and thereby regulate gene expression. With exquisite specificity, metabolite‐sensing riboswitches control the formation or translation of prokaryotic mRNA. In eukaryotes, RNA sensors in human antiviral cytokine genes that encode tumour necrosis factor‐α (TNF‐α) and interferon‐γ (IFN‐γ) have been shown to activate strongly the RNA‐dependent protein kinase PKR, a stress kinase that is also activated by double‐stranded RNA—a hallmark of viral infection. These cis‐acting RNA elements in the TNF‐α and IFN‐γ transcripts function as sensors of intracellular PKR levels and regulate gene expression at the level of mRNA splicing and translation, respectively. Although RNA sensors in bacteria may be remnants of an ancient RNA world, it is likely that they form an integral part of higher eukaryotic genomes as well.
Genome‐wide distribution of DNA replication origins at A+T‐rich islands in Schizosaccharomyces pombe
Authors: Segurado Mónica , de Luis Alberto , Antequera Francisco
Published: June 2004

Genome‐wide analysis of replication dynamics requires the previous identification of DNA replication origins (ORIs). However, variability among the ORIs makes it difficult to predict their distribution across the genome on the basis of their sequence. We report here that ORIs in Schizosaccharomyces pombe coincide with discrete chromosomal A+T‐rich islands of up to 1 kb long that are characterized by a distinctive A+T content that clearly differentiates them from the rest of the genome. Genome‐wide analysis has enabled us to identify 384 of these regions, which predicts the position of most ORIs in the genome, as shown by functional replication analyses. A+T‐rich islands occur at the mating locus, centromeres and subtelomeric regions at a density that is approximately fourfold higher than elsewhere in the genome, which suggests a link between the origin recognition complex (ORC) and transcriptional silencing in these regions. The absence of consensus elements in A+T‐rich islands implies that different sequences can target the ORC to different ORIs.
Dual targeting and function of a protease in mitochondria and chloroplasts
Authors: Bhushan Shashi , Lefebvre Benoit , Ståhl Annelie , Wright Sarah J , Bruce Barry D , Boutry Marc , Glaser Elzbieta
Published: June 2004

Here we show, using the green fluorescent protein (GFP) fusion system, that an Arabidopsis thaliana zinc‐metalloprotease (At Zn‐MP) is targeted to both mitochondria and chloroplasts. A deletion mutant lacking the amino‐terminal 28 residues, with translation initiation at the second methionine residue, was imported into chloroplasts only. However, a mutated form of the full‐length targeting peptide, in which the second methionine residue is changed to leucine, was imported to both organelles. No GFP fluorescence was detected when a frame‐shift mutation was introduced between the first and second ATG codons of the Zn‐MP–GFP construct, suggesting no alternative translational initiation. Our results show that the dual targeting of the Zn‐MP is due to an ambiguous targeting peptide. Furthermore, we show that the recombinant At Zn‐MP degrades mitochondrial and chloroplastic targeting peptides, indicating its function as a signal peptide degrading protease in both mitochondria and chloroplasts.
Pre‐TCR‐triggered ERK signalling‐dependent downregulation of E2A activity in Notch3‐induced T‐cell lymphoma
Authors: Talora Claudio , Campese Antonio F , Bellavia Diana , Pascucci Monica , Checquolo Saula , Groppioni Manuela , Frati Luigi , von Boehmer Harald , Gulino Alberto , Screpanti Isabella
Published: June 2004

Notch and basic helix–loop–helix E2A pathways specify cell fate and regulate neoplastic transformation in a variety of cell types. Whereas Notch enhances tumorigenesis, E2A suppresses it. However, whether and how Notch and E2A interact functionally in an integrative mechanism for regulating neoplastic transformation remains to be understood. It has been shown that Notch3‐induced T‐cell leukaemia is abrogated by the inactivation of pTα/pre‐T‐cell antigen receptor (pre‐TCR). We report here that Notch3‐induced transcriptional activation of pTα/pre‐TCR is responsible for the downregulation of E2A DNA binding and transcriptional activity. Further, the E2A messenger RNA and protein levels remain unaltered but the E2A inhibitor Id1 expression is augmented in thymocytes and T lymphoma cells derived from Notch3 transgenic mice. The increase in Id1 expression is achieved by pre‐TCR‐induced extracellular‐signalling‐regulated kinase 1/2. These observations support a model in which the upregulation of pre‐TCR signalling seems to be the prerequi‐site for Notch3‐induced inhibition of E2A, thus leading to the development of lymphoma in Notch3 transgenic mice.
Measuring impacts of an holistic farm business management training program
Authors: Cameron D. , Chamala S. A.
Published: June 2004

A case study approach within an action research framework incorporating qualitative and quantitative domains was adopted to explore the impact on Queensland farmers of a farm business management extension programme. Three new indices were developed to quantify changes perceived by participants. The first measure, the Bennett Change Index, provided statistically significant evidence that attitudinal and behavioural changes were more frequent in participants with less formal education, but also more frequent in participants who had high urbanisation and self-directed learning index scores. The other 2 new indices, Management Constructs Change and Management Objectives Change, provided evidence of statistically significant changes in participant beliefs about, and attitudes towards, farm business management. Although highly correlated with each other, these changes were unrelated statistically to any of 6 other commonly used biographical or psychometric indices employed; including level of formal education. It is concluded that these new measures, with context-relevant modifications, have potential as aids to programme impact evaluation in a range of agricultural and wider applications. They may provide insights into personal psychological issues that complement direct behavioural measures of change.
Root growth altered by compaction of a sandy loam soil affects severity of rhizoctonia root rot of wheat seedlings
Authors: Gill J. S. , Hunt S. , Sivasithamparam K. , Smettem K. R. J.
Published: June 2004

Rhizoctonia solani Anastomosis Group 8 damages seedling roots of wheat, causing the 'bare-patch' disease. This makes the first 4 weeks after germination the most critical period for disease development. As the field inoculum of the pathogen is mainly concentrated in the surface 10 cm of soil, the rate of root growth becomes critical for the vulnerable tissues of the root to escape the attack from the inoculum zone. To evaluate the effect of alteration of root growth by soil compaction on disease severity, a study was undertaken in 40-cm-deep pots made from PVC pipes (8.7 cm diameter). Four depths of soil compaction (whole soil profile compacted, whole soil loose, upper 10 cm loose and compacted below, upper 20 cm loose and compacted below) were tested using sieved soil. Effective root length of infected seedlings was higher in the pots where the whole soil profile was compacted than others. Reduction in dry root weights, where soil was compacted to heights of 0, 17.5, 27.5 or 37.5 cm following inoculation, were 68, 30, 74 and 56%, respectively. Reduction in shoot weights was 52, 22, 66 and 44%, respectively. Eight days after incubation, microbial activity was greater where the soil was highly compacted than where there was a low level of soil compaction. Saprophytic growth in soil of Rhizoctonia solani Anastomosis Group 8 was higher in loosely packed soil than in compacted soil. This shows that higher impact of disease under compacted soil conditions is due to reduced root growth and that disturbing the soil below seeds can reduce the impact of disease.
Sustaining productivity of a Vertosol at Warra, Queensland, with fertilisers, no-tillage or legumes. 7. Yield, nitrogen and disease-break benefits from lucerne in a two-year lucerne - wheat rotation
Authors: Dalal R. C. , Weston E. J. , Strong W. M. , Lehane K. J. , Cooper J. E. , Wildermuth G. B. , King A. J. , Holmes C. J.
Published: June 2004

Continuous cultivation and cereal cropping of southern Queensland soils previously supporting native vegetation have resulted in reduced soil nitrogen supply, and consequently decreased cereal grain yields and low grain protein. To enhance yields and protein concentrations of wheat, management practices involving N fertiliser application, with no-tillage and stubble retention, grain legumes, and legume leys were evaluated from 1987 to 1998 on a fertility-depleted Vertosol at Warra, southern Queensland. The objective of this study was to examine the effect of lucerne in a 2-year lucerne–wheat rotation for its nitrogen and disease-break benefits to subsequent grain yield and protein content of wheat as compared with continuous wheat cropping.Dry matter production and nitrogen yields of lucerne were closely correlated with the total rainfall for October–September as well as March–September rainfall. Each 100 mm of total rainfall resulted in 0.97 t/ha of dry matter and 26 kg/ha of nitrogen yield. For the March–September rainfall, the corresponding values were 1.26 t/ha of dry matter and 36 kg/ha of nitrogen yield. The latter values were 10% lower than those produced by annual medics during a similar period. Compared with wheat–wheat cropping, significant increases in total soil nitrogen were observed only in 1990, 1992 and 1994 but increases in soil mineralisable nitrogen were observed in most years following lucerne. Similarly, pre-plant nitrate nitrogen in the soil profile following lucerne was higher by 74 kg/ha (9–167 kg N/ha) than that of wheat–wheat without N fertiliser in all years except 1996. Consequently, higher wheat grain protein (7 out of 9 seasons) and grain yield (4 out of 9 seasons) were produced compared with continuous wheat. There was significant depression in grain yield in 2 (1993 and 1995) out of 9 seasons attributed to soil moisture depletion and/or low growing season rainfall. Consequently, the overall responses in yield were lower than those of 50 kg/ha of fertiliser nitrogen applied to wheat–wheat crops, 2-year medic–wheat or chickpea–wheat rotation, although grain protein concentrations were higher following lucerne.The incidence and severity of the soilborne disease, common root rot of wheat caused by Bipolaris sorokiniana, was generally higher in lucerne–wheat than in continuous wheat with no nitrogen fertiliser applications, since its severity was significantly correlated with plant available water at sowing. No significant incidence of crown rot or root lesion nematode was observed. Thus, productivity, which was mainly due to nitrogen accretion in this experiment, can be maintained where short duration lucerne leys are grown in rotations with wheat.
Surface soil water dynamics in pastures in northern New South Wales. 3. Evapotranspiration
Authors: Murphy S. R. , Lodge G. M. , Harden S.
Published: June 2004

Evapotranspiration is the major component of the hydrological balance of grazed pastures on the North-West Slopes of New South Wales, representing up to 93% of annual rainfall. Nearly 80% of evapotranspiration may occur as bare soil evaporation, however, representing water not available for plant growth. Few studies have reported daily values of actual evapotranspiration for pastures, particularly in northern New South Wales. The studies reported here were conducted to measure actual evapotranspiration using an evaporation dome technique, for plots with a range of pasture, litter and ground cover. Measurements were taken in each season between autumn 2000 and autumn 2001, with both wet and dry soil surface conditions, to document the range of values that might be expected. Similar measurements were conducted in areas of natural pasture, to quantify values under grazed conditions. A range of other variables were also quantified in association with each evapotranspiration measurement; these included components of net radiant energy, atmospheric conditions, pasture physical characteristics, ground cover and soil water content. These data were used to identify the most important variables, which may be influenced by or interact with grazing management, that account for variation in daily evapotranspiration values.Hourly evapotranspiration ranged from 0.02 to 0.82 mm/h and daily values ranged from 0.2 to 7.6 mm/day, in winter to summer, respectively. Linear regression models that included variables of solar radiation, herbage mass, vapour pressure deficit and soil water content accounted for up to 93% of the variation in daily evapotranspiration values. These models predicted that high litter mass (3000 kg DM/ha) may reduce evaporation by up to 1 mm/day for wet soils, making a substantial contribution to the annual hydrological balance. A simulation study of a grazed pasture, using the Sustainable Grazing Systems Pasture Model, indicated that grazing management may influence the partitioning of transpiration and evaporation from canopy, litter and bare soil. With rotational grazing, predicted soil evaporation was lower and transpiration and canopy evaporation were higher than with continuous grazing. Hence, pastures may require different management between summer and winter, so that bare soil evaporation and canopy interception losses are minimised, to maximise stored soil water available for pasture use. Pastures with lower evaporative losses are likely to have higher productivity and sustainability.
Effect of postharvest mechanical stress on quality and storage life of Chinese cabbage cv. Yuki
Authors: Porter K. , Collins G. , Klieber A.
Published: June 2004

The effects of 3 common handling procedures and mishaps (dropping, compression and trimming) applied to Chinese cabbage cv. Yuki [Brassica campestris L. ssp. pekinensis (Lour.) Olsson] were compared to unstressed control cabbages. Heads were mechanically stressed by dropping from 50 cm onto a hard floor, by prolonged compression under 3 kg of weight before storage, or by repeated trimming of the outer leaves during storage. Cabbages were stored at 2°C for 9 weeks. Market quality of cabbages was not affected by the mechanical stresses, but storage for 9 weeks reduced marketable quality. Heads that were repeatedly trimmed produced less ethylene at the end of the storage period compared to the start, and less ethylene than the other treatments (due to the removal of outer senescing and rotting leaves); however, marketable yield was not improved.
Crop isolation, not extended rotation length, reduces blackleg (Leptosphaeria maculans) severity of canola (Brassica napus) in south-eastern Australia
Authors: Marcroft S. J. , Sprague S. J. , Pymer S. J. , Salisbury P.A. , Howlett B. J.
Published: June 2004

Due to the large increase of canola production in Australia, current blackleg cultural control recommendations (extended rotation length and isolation distance from canola stubble) are not adhered to by farmers in many canola-producing regions. Canola crops are increasingly being sown in short rotation and, in many instances, adjacent to paddocks containing canola stubble. In this study, the level of disease in commercial canola crops was determined for different rotations and distances from canola stubble. There was a strong relationship between the presence of canola stubble from the previous year (6-month-old stubble) and distance to current canola crops, but no relationship between the presence of older (18–42 month old) stubble and distance to current canola crops. Blackleg severity was highest where canola crops had been sown adjacent to 6-month-old canola stubble, with the level of blackleg severity decreasing markedly in the first 100 m. Disease severity then generally declined up to 500 m. Plants 500–1000 m from 6-month-old stubble had similar levels of blackleg infection. Blackleg severity was similar between canola crops sown into 18-month-old canola stubble (short rotation) and crops sown into paddocks that had no history of canola for at least the previous 3 years (long rotation). Based on these findings, we recommend that canola crops should be sown at distances greater than 100 m and preferably 500 m from last season's canola stubble, rather than extending rotation length between crops.
Grazing of pasture weeds by goats and sheep. 1. Nodding thistle (Carduus nutans)
Authors: Holst P. J. , Allan C. J. , Campbell M. H. , Gilmour A. R.
Published: June 2004

Goats and sheep grazed replicate plots of perennial pasture infested with nodding thistle (Carduus nutans). Neither goats nor sheep ate the vegetative thistle until it reached ~30 cm in diameter at which time goats consumed outer leaves on some plants. Active goat grazing commenced at flowering as the capitula matured from green to purple, with subsequent preferential grazing of the purple capitula in the presence of abundant pasture (2500 kg green DM/ha). The stage of maturation of the thistle influenced the proportion of purple capitula eaten by goats. Over the extended (5 month) 1991–92 flowering period induced by above average summer rain, dispersal of viable seeds was prevented in goat-grazed plots as goats ate 100% of the flowering stems. In the short 1992–93 flowering season (1.5 months) dry conditions resulted in seedheads rapidly maturing from green to brown. Goat numbers were insufficient to eat 100% of capitula as they reached the palatable stage. Consequently viable seeds were dispersed. Sheep consumed the thistle capitula only when pasture became limiting, allowing viable seeds to be dispersed in both flowering seasons. Spraying with non-lethal doses of herbicide increased the proportion of vegetative thistles consumed by both sheep and goats. Goats selectively removed maturing capitula then grazed the stems of the nodding thistle. As goats consumed thistle capitula throughout the flowering period, the quantity of pasture in goat plots exceeded that in sheep plots, principally due to an increase in the proportion of clover. The stocking density of goats required to control nodding thistle is proportionate to the level of weed infestation and must be modified as a response to prevailing seasonal conditions and rate of removal of purple capitula. Grazing of the purple capitula of nodding thistle by goats in lieu of pasture indicates the potential for mixed animal species grazing of weed-infested pastures.
Grazing of pasture weeds by goats and sheep. 2. Scotch broom (Cytisus scoparius L.)
Authors: Holst P. J. , Allan C. J. , Campbell M. H. , Gilmour A. R.
Published: June 2004

Sheep and goats were allocated to 1.6 ha paddocks containing populations of scotch broom with 4–10%�ground cover and grazed by either 4 sheep or 6 goats. Subjective scoring of defoliation and persistence was conducted at 4–8-weekly intervals over almost 2 years. While the sheep had minimal impact on the vigour of the broom plants, goats had a major impact when broom density was low (4% ground cover) but no impact when broom density was at 10% ground cover. This same pattern was evident for defoliation. Goats also stripped bark from broom stems during winter increasing broom ill thrift in goat paddocks. While sheep browsed up to 90 cm height, goats browsed up to 120 cm at low broom density. Both sheep and goats removed stem and flowering points preventing seed production within browse reach and also removed the new broom shoots over summer, whereas sheep preferred pasture once it became more abundant. Pasture availability was greater in goat-grazed paddocks over the flowering period and when new shoots were produced by broom. When broom seeds were fed to goats, 8%�of the seeds remained viable following ingestion.
A revision of the genus Pultenaea (Fabaceae). 3. The eastern species with recurved leaves
Authors: Kok R. P. J. de , West J. G.
Published: June 2004

All 37 eastern species of the genus Pultenaea Sm. with recurved leaves have been revised and two names are reduced to synonymy for the first time. Four new species are described: Pultenaea tarik de Kok, P.�borea de Kok, P.�bracteamajor de Kok and P.�bracteaminor de Kok. One taxon is given a new name: P.�rariflora de Kok (�=�Pultenaea paleacea var. pauciflora C.T.White). Two taxa are recognised in this study at the species level for the first time: P.�elusa (J.D. Briggs & Crisp) de Kok and P.�robusta (H.B.Will.) de Kok. For one species: P.�elachista (F.Muell.) Crisp, a neotype is proposed. Seven species are lectotypified (P.�benthamii F.Muell., P.�densifolia F.Muell., P. gunnii Benth., P.�largiflorens F.Muell. ex Benth., P.�myrtoides A.Cunn. ex Benth., P.�patellifolia H.B.Will. and P.�retusa Sm.). Two species (P.�elusa and P.�maidenii Reader) are considered extinct in this study. A key to the group is provided and a brief discussion is given as to the legitimacy of these species being treated as a separate group. A list of all accepted names and synonyms of the eastern species of Pultenaea is given.
Foraging behaviour of the black flying-fox (Pteropus alecto) in the urban landscape of Brisbane, Queensland
Authors: Markus Nicola , Hall Les
Published: June 2004

The foraging movements of 13 Pteropus alecto from four camps in suburban Brisbane were monitored over two summer and one winter season between 1998 and 2000. By means of radio-telemetry, the flying-foxes were tracked to their foraging sites over 49 nights for a total of 237 h. Data from flying-foxes tracked from dusk to dawn showed that bats travelled directly to a foraging site early in the night and undertook smaller movements between foraging sites for the remainder of the night. Bats undertook a greater number of nocturnal movements during a food resource shortage than during a season of greater resource abundance. Mean distances (±s.e.) travelled from camps to foraging sites varied between camps and ranged from 2.9 ± 0.3 km (n = 24) to 7.6 ± 0.07 km (n = 2). In all three seasons, flying-foxes foraged on a variety of native and exotic plant species. Dominant exotics included Cocos palms (Sygarus romanzoffiana), Chinese elm trees (Celtis sinensis) and Cadaghi (Corymbia torrelliana), while highly utilised native food plants included figs (Ficus spp.), grevilleas (Grevillea spp.) and bottlebrushes (Callistemon spp.).
Efficacy of zinc phosphide, strychnine and chlorpyrifos as rodenticides for the control of house mice in South Australian cereal crops
Authors: Mutze Greg , Sinclair Ron
Published: June 2004

Replicated field trials were conducted to compare the efficacy of zinc phosphide, strychnine and chlorpyrifos for the control of house mice (Mus domesticus) infesting recently sown wheat crops in South Australia. Bait was prepared using whole-wheat grain or grain-based pellets and broadcast into the crops at 1 kg ha–1. Treatment with zinc phosphide reduced mouse numbers by 98%. Two treatments with strychnine baits, applied 11 days apart, also reduced mouse numbers by 98% with no evidence of bait aversion in mice that survived the initial treatment. On the basis of these and other published results, zinc phosphide is considered an effective alternative to strychnine for control of house mice in cereal crops. Chlorpyrifos baits reduced mouse numbers by less than 10%. The trial began too late in the growing season to prevent substantial mouse damage to seed grain and seedlings. The number of seedlings established at treatment time one month after sowing explained 84% of variation in crop yield. Mouse damage is estimated to have reduced yield by more than 0.5 t ha–1 or 15% of potential yield and cost the grower more than $30 000 in lost production from the 300-ha study area.
Diet and habitat preference of the Cape York short-nosed bandicoot (Isoodon obesulus peninsulae) in north-east Queensland
Authors: Keiper P. , Johnson C. N.
Published: June 2004

Diet and habitat preferences of the Cape York bandicoot (Isoodon obesulus peninsulae) were studied along a rainfall gradient from dry open woodland to wet Allocasuarina–Eucalyptus forest in the Lamb Range, Queensland. I. o. peninsulae was an omnivore-insectivore with invertebrates contributing 35–56% of faecal contents. Roots represented the most important plant food. Grass, forbs, fruits and hypogeous fungi were also eaten but in small quantities. The species was most abundant at the drier end of the rainfall gradient. Preferred habitats in open woodland were characterised by a high grass tree (Xanthorrhoea johnsonii) abundance and high shrub cover in the understorey. In contrast, areas with a tall and dense grass layer in conjunction with a high litter cover were avoided. I. o. peninsulae did not seem to share its habitat with the sympatrically occurring I. macrourus even though the habitat appeared suitable for the latter. More studies are required to evaluate the causes of differing habitat preferences of sympatric bandicoot species.
Migration patterns of marine turtles in the Gulf of Carpentaria, northern Australia: implications for Aboriginal management
Authors: Kennett Rod , Munungurritj N. , Yunupingu Djawa
Published: June 2004

Marine turtles regularly migrate hundreds to thousands of kilometres between nesting beaches and home foraging grounds. Effective conservation of marine turtles requires understanding of migration patterns in order to facilitate regional cooperation across the turtles' migratory range. Indigenous Australians maintain traditional rights and responsibilities for marine turtle management across much of the northern Australian coast. To better understand turtle migrations and identify with whom the Aboriginal people of north-east Arnhem Land (Yolngu) share turtles, we used satellite telemetry to track the migration routes of 20 green turtles (Chelonia mydas) departing from a nesting beach ~45 km south of Nhulunbuy, north-east Arnhem Land, Northern Territory, Australia. All tracked turtles remained within the Gulf of Carpentaria. These results suggest that the foraging habitat for adults of this nesting population may be largely confined to the Gulf, offering an optimistic scenario for green turtle conservation. Given these results and the critical role indigenous people play in conserving and managing marine turtles, we recommend that a formal network of indigenous communities be established as the foundation of a community-based turtle-management strategy for the Gulf of Carpentaria region.