School of Agriculture and Food Sciences - UQ eSpace

An evolutionary radiation of beeflies in semi-arid Australia: systematics of the Exoprosopini (Diptera : Bombyliidae)

2007-08-15T00:00:00Z

Almost half of the 4822 described beeflies in the world belong to the subfamily Anthracinae, with most of the diversity found in three cosmopolitan tribes: Villini, Anthracini, and Exoprosopini. The Australian Exoprosopini previously contained three genera, Ligyra Newman, Pseudopenthes Roberts and Exoprosopa Macquart. Pseudopenthes is an Australian endemic, with two species including Ps. hesperis, sp. nov. from Western Australia. Two new species of the exoprosopine Atrichochira Hesse, Atr. commoni, sp. nov. and Atr. paramonovi, sp. nov., are also described from Australia, extending the generic distribution from Africa. Cladistic analysis clarified the phylogenetic relationships between the recognised groups of the Exoprosopini and determined generic limits on a world scale. Inclusion of 18 Australian exoprosopines placed the Australian species in the context of the world fauna. The Exoprosopini contains six large groups. The basal group I contains species previously included in Exoprosopa to which the name Defilippia Lioy is applied. Group II contains Heteralonia Rondani, Atrichochira, Micomitra Bowden, Pseudopenthes, and Diatropomma Bowden. Colossoptera Hull is newly synonymised with Heteralonia. Group III is a paraphyletic assemblage of Pterobates Bezzi and Exoprosopa including the Australian Ex. sylvana ( Fabricius). Ligyra is paraphyletic, forming two well-separated clades. The African clade is described as Euligyra Lambkin, gen. nov., which, together with Litorhina Bezzi and Hyperalonia Rondani, form group IV. The Australian group V is true Ligyra. The remaining monophyletic lineage of exoprosopines, group VI, the Balaana-group of genera, shows evidence of an evolutionary radiation of beeflies in semi-arid Australia. Phylogenetic analysis of all 42 species of the Balaana-group of genera formed a basis for delimiting genera. Seven new genera are described by Lambkin & Yeates: Balaana, Kapua, Larrpana, Munjua, Muwarna, Palirika and Wurda. Four non-Australian species belong to Balaana. Thirty two new Australian species are described: Bal. abscondita, Bal. bicuspis, Bal. centrosa, Bal. gigantea, Bal. kingcascadensis, K. corusca, K. irwini, K. westralica, Lar. collessi, Lar. zwicki, Mun. erugata, Mun. lepidokingi, Mun. paralutea, Mun. trigona, Muw. vitreilinearis, Pa. anaxios, Pa. basilikos, Pa. blackdownensis, Pa. bouchardi, Pa. cyanea, Pa. danielsi, Pa. decora, Pa. viridula, Pa. whyalla, W. emu, W. impatientis, W. montebelloensis, W. norrisi, W. patrellia, W. skevingtoni, W. windorah, and W. wyperfeldensis. The following new combinations are proposed: from Colossoptera: Heteralonia latipennis (Brunetti); from Exoprosopa: Bal. grandis (Pallas), Bal. efflatounbeyi (Paramonov), Bal. latelimbata ( Bigot), Bal. obliquebifasciata ( Macquart), Bal. tamerlan (Portschinsky), Bal. onusta ( Walker), Def. busiris (Jaennicke), Def. efflatouni ( Bezzi), Def. eritreae (Greathead), Def. gentilis ( Bezzi), Def. luteicosta ( Bezzi), Def. minos (Meigen), Def. nigrifimbriata ( Hesse), Def. rubescens ( Bezzi), K. adelaidica ( Macquart), Lar. dimidiatipennis ( Bowden), Muw. stellifera ( Walker), and Pa. marginicollis ( Gray); from Ligyra: Eu. enderleini ( Paramonov), Eu. mars ( Bezzi), Eu. monacha (Klug), Eu. paris ( Bezzi), Eu. sisyphus ( Fabricius), and Eu. venus (Karsch).

A new Babesia species isolated from an Eastern Grey Kangaroo (Macropus gigantus) in SE Queensland

2011-10-22T00:00:00Z

A new chemovar of Gympie messmate (Eucalyptus cloeziana F. Muell.) containing a-pinene and tasmanone

2008-06-10T00:00:00Z

A new data source for fisheries resource assessment: Genetic estimates of the effective number of spawners. Final Report to the Fisheries Research and Development Corporation.

2009-04-07T00:00:00Z

The development of innovative methods of stock assessment is a priority for State and Commonwealth fisheries agencies. It is driven by the need to facilitate sustainable exploitation of naturally occurring fisheries resources for the current and future economic, social and environmental well being of Australia. This project was initiated in this context and took advantage of considerable recent achievements in genomics that are shaping our comprehension of the DNA of humans and animals. The basic idea behind this project was that genetic estimates of effective population size, which can be made from empirical measurements of genetic drift, were equivalent to estimates of the successful number of spawners that is an important parameter in process of fisheries stock assessment.

A new essential oil from Eucalyptus dura L.A.S. Johnson & K.D. Hill

2008-06-10T00:00:00Z

A new generalized growth threshold for dynamic SOM for comparing average mutual information and oligonucleotide frequency as a species signature

Chan, Chon-Kit Kenneth og Halgamuge, Saman — 2011-03-22T00:00:00Z

The average mutual information (AMI) known from information theory has been reported as a strong genome signature in some literature and we have reported the use of oligonucleotide frequencies as a genome signature. In this work we improve the use of AMI as a training feature for Growing Self Organising Maps (GSOM). Although the range of k is considered as an important parameter in AMI, no standard range for k is proposed. Our first contribution is to introduce a new growth threshold (GT) for GSOM and use it to identify the best range of k for clustering prokaryotic sequence fragments of 10 kb. We then, compare the results using the best k range of AMI against our previously published results using oligonucleotide frequencies. These experiments showed that the newly proposed GT equation makes GSOM able to efficiently and effectively analyse different data features for the same data. The results also emphasize our use of oligonucleotide frequencies as opposed to AMI.

A new heat load index for feedlot cattle

2009-04-02T15:25:05Z

A new method for isolating large quantities of Arabidopsis trichomes for transcriptome, cell wall and other types of analyses

2010-01-13T00:00:00Z

A new procedure has been developed for the isolation of wild-type and mutant Arabidopsis trichomes. The isolated trichomes maintained enzymatic activity and were used for DNA, protein, and RNA isolation. The RNA was used to generate probes suitable for Affymetrix analysis. The validity of the Affymetrix results was confirmed by quantitative PCR analysis on a subset of genes that are preferentially expressed in trichomes or leaves. Sufficient quantities of trichomes were isolated to probe the biochemical nature of trichome cell walls. These analyses provide evidence for the presence of lignin in Arabidopsis trichome cell walls. The monosaccharide analysis and positive staining with ruthenium red indicates that the walls also contain a large portion of pectin. The 2.23-fold ratio of pectin-related sugars compared with potential cellulosic glucose suggests that the polysaccharides of the trichome cell walls are more like those of typical primary walls even though the wall becomes quite thick. Overall, these analyses open the door to using the Arabidopsis trichome cell wall as an excellent model to probe various questions concerning plant cell wall biosynthesis. © 2009 Blackwell Publishing Ltd and the Society for Experimental Biology.

A new method for producing allohexaploid Brassica through unreduced gametes

2012-06-25T15:51:54Z

A new method of producing date powder granules: Physicochemical characteristics of powder

2009-04-17T00:00:00Z

A mixing technique was developed to produce free flowing powder granules from date. This method involved preparation of the paste from raw date, mixing with maltodextrin powder followed by an oven drying. In order to determine an optimum proportion of date paste and maltodextrin (DE 6) to produce stable granules, mixing was carried out at various levels of maltodextrin (MD) ranging between 0.54 kg and 1.0 kg per kg of date paste (dry weight basis). The date paste dried with 1.0 kg of maltodextrin/1.0 kg of date paste produced non sticky and free flowing powder. Several physicochemical parameters such as water activity, bulk density, color, hygroscopicity and glass transition temperatures of date powders were measured. The caking of date powders during storage at room temperature was explained using the concept of glass transition temperature.

A new NMR method for directly monitoring and quantifying the dissolution kinetics of starch in DMSO

2008-03-28T00:00:00Z

The kinetics of dissolution of starch is needed for (i) understanding digestive processes; (ii) providing data that could correlate with higher levels of starch structure; (iii) improving techniques for starch characterization in solution. A novel method is presented here to directly monitor these dissolution kinetics by time-resolved 1H solution-state nuclear magnetic resonance (NMR); studies were carried out in deuterated dimethyl sulfoxide (DMSO-d6). By assuming pseudo-first-order kinetics with respect to starch concentration, the data for various starch samples yield values of the apparent rate coefficients for the rate of appearance of completely dissolved anhydroglucose units, results which have not been obtained hitherto. The presence of a limited amount of water in DMSO had a drastic effect on dissolution kinetics (slowing it down at high temperatures), indicating multiple pathways for the dissolution mechanism. Dynamic light scattering (DLS) appears to be more limited than the NMR method to monitor the kinetics of dissolution. The newly developed NMR method can be extended to other solvents and polysaccharides.

A new species of eriophyoid mite (Acari : Eriophyidae) on sugarcane in Australia

2007-08-15T00:00:00Z

Seven species of eriophyoid mites (Acari: Eriophyoidea) are known to attack sugarcane plants (Saccharum spp., Poaceae) and related grasses in various parts of the world, but except for unconfirmed reports of Aceria sacchari and Abacarus sacchari, Australia had been thought to be free of these pests. Herein, Abacarus queenslandiensis n. sp. (Eriophyidae), vagrant on leaf surfaces of sugarcane in Australia, is described. Also, Cathetacarus n. gen. is erected for the distinctive mite, Catarhinus spontaneae Mohanasundaram, 1984. In addition, a key to the eriophyoid mites known to occur on sugarcane plants in the world is given.

A new technique for coconut (Cocos nucifera) germplasm collection from remote sites: culturability of embryos following low-temperature incubation

2008-06-10T00:00:00Z

A new technique for coconut (Cocos nucifera L.) germplasm collection was evaluated in the laboratory and tested in the field in Indonesia. The technique involved the non-sterile isolation of embryos, and incubation in sterile ascorbic acid solution (1 mg L-1) at 5 +/- 1 degrees C in the dark. During this incubation period the embryos could be transported and/or stored for a period of up to 4 days without embryo viability loss. Following this period the embryos were surface sterilised with sodium hypochlorite (1.5% w/v) for 20 min, washed with sterile water and cultured in a liquid Y3 basal nutrient medium supplemented with Morel and Wetmore vitamins, sucrose (175 mM) and activated charcoal (2.5 g L-1). After two weeks the embryos were subcultured onto a solid medium of similar constitution to encourage germination. Germinated embryos grew and produced healthy plants with normal morphology. Despite mild chilling injury as indicated by elevated ethylene production and solute leakage, the transported embryos retained viability with normal morphology. Using the low-temperature incubation treatment, the microorganism density in the ascorbic acid solution was kept low while that around other embryos kept at higher temperatures (25 degrees C) increased. Even though embryos were exposed to a low-temperature treatment for up to 4 days they were able to germinate (95% viable) and grow in an identical fashion to freshly cultured embryos.

An examination of the attitudes and behaviours of ethnic Chinese wine consumers: An exploratory study

2012-03-19T00:00:00Z

Qualitative focus group interviews were performed with ethnic Chinese wine consumers residing in Adelaide, South Australia. The purpose of the interviews was t o explore wine related attitudes and behaviours unique to Chinese consumers. The major findings of the study revealed a preference for sweet wine styles and cork closed wine bottles. The practise of mixing red wine with lemonade was discussed. Participants believed that wine was good for their health particularly in maintaining a healthy cardiovascular system and a medicinal administration of wine for a positive health effect was observed.

An experimental approach for developing seed lines of new Australian native flowering pot plants

2013-02-24T00:31:17Z

An exploration of livestock-development policies in western China

2012-03-06T00:00:00Z

Limited agricultural land potential, poorly integrated markets and low rural incomes are all interrelated problems for agricultural households in western China. Within the wide range of development options available, this paper focuses on the impact of forage-growing subsidies and reducing livestock feed trade barriers on agricultural household incomes and enterprise mixes in the Qingyang Prefecture of Gansu Province, China. A heterogeneous-agent model is used to assess the local consequences of these two policies. Data from a survey conducted in 2009 are used as inputs into the model. The results indicate that a simultaneous reduction in livestock feed trade barriers and an introduction of forage-growing subsidies lifts net household incomes by approximately 10%. Different scenarios have different impacts on incomes, land allocation decisions and grain purchases, with heterogeneity also found among household income responses. Livestock-development policies have the potential to lift household incomes however there are tradeoffs between income and grain self-sufficiency.

An identification tool for the Australian weedy Sporobolus species based on random amplified polymorphic DNA (RAPD) profiles

2007-08-15T00:00:00Z

Based on morphological features alone, there is considerable difficulty in identifying the 5 most economically damaging weed species of Sporobolus [ viz. S. pyramidalis P. Beauv., S. natalensis ( Steud.) Dur and Schinz, S. fertilis ( Steud.) Clayton, S. africanus (Poir.) Robyns and Tourney, and S. jacquemontii Kunth.] found in Australia. A polymerase chain reaction (PCR)-based random amplified polymorphic DNA ( RAPD) technique was used to create a series of genetic markers that could positively identify the 5 major weeds from the other less damaging weedy and native Sporobolus species. In the initial RAPD pro. ling experiment, using arbitrarily selected primers and involving 12 species of Sporobolus, 12 genetic markers were found that, when used in combination, could consistently identify the 5 weedy species from all others. Of these 12 markers, the most diagnostic were UBC51(490) for S. pyramidalis and S. natalensis; UBC43(310,2000,2100) for S. fertilis and S. africanus; and OPA20(850) and UBC43(470) for S. jacquemontii. Species-specific markers could be found only for S. jacquemontii. In an effort to understand why there was difficulty in obtaining species-specific markers for some of the weedy species, a RAPD data matrix was created using 40 RAPD products. These 40 products amplified by 6 random primers from 45 individuals belonging to 12 species, were then subjected to numerical taxonomy and multivariate system (NTSYS pc version 1.70) analysis. The RAPD similarity matrix generated from the analysis indicated that S. pyramidalis was genetically more similar to S. natalensis than to other species of the 'S. indicus complex'. Similarly, S. jacquemontii was more similar to S. pyramidalis, and S. fertilis was more similar to S. africanus than to other species of the complex. Sporobolus pyramidalis, S. jacquemontii, S. africanus, and S. creber exhibited a low within-species genetic diversity, whereas high genetic diversity was observed within S. natalensis, S. fertilis, S. sessilis, S. elongates, and S. laxus. Cluster analysis placed all of the introduced species ( major and minor weedy species) into one major cluster, with S. pyramidalis and S. natalensis in one distinct subcluster and S. fertilis and S. africanus in another. The native species formed separate clusters in the phenograms. The close genetic similarity of S. pyramidalis to S. natalensis, and S. fertilis to S. africanus may explain the difficulty in obtaining RAPD species-specific markers. The importance of these results will be within the Australian dairy and beef industries and will aid in the development of integrated management strategy for these weeds.

Animal care staff and management opinions differ on constraints involved with enrichment

Hoy, J og Murray, P og Tribe, A — 2011-03-08T00:00:00Z

Animal experts answer your questions

Blackshaw, J. K. — 2007-08-14T00:00:00Z

Animal handling as an integrated component of animal and veterinary science programs at the University of Queensland

2008-05-06T00:00:00Z

Animal industry benefits from improved welfare

Phillips, C.J.C. — 2010-04-14T00:00:00Z

Animal management in the Australian rangelands

2010-01-11T00:00:00Z

Animal Nutrition Science

Dryden, Gordon McL. — 2009-04-15T00:00:00Z

Animal-Plant Interactions in Rainforest Restoration in Tropical and Subtropical Australia

2007-08-23T00:00:00Z

Animal production: Monochrone or technicolour

Young, B. og Goodwin, P. J. og Liang, J.B. — 2007-08-24T00:00:00Z

Animal production potential of some new Leucaena accessions in the Markham valley, Papua New Guinea

2007-08-15T00:00:00Z

Signal grass pastures were oversown with four Leucaena spp. planted in hedgerows and evaluated for their agronomic productivity and ability to support steer liveweight gains. Each Leucaena sp. (L. leucocephala, L. pallida, L colli. nst. i., L. trichandra) was planted as seedlings into two I ha paddocks in rows 5 m apart, with I m spacing between trees. Cattle were rotationally grazed on the 2 replicates of each species, as well as on two I ha paddocks of a signal grass on y (Brachiaria decumbens) control, over a 243-day period at a stocking rate of 3 steers/ha. Mean presentation yield and herbage allowance of the Leucaena accessions over the grazing period were highest for L pallida (1100 kg/ha and 0.8 kg DM/kg LW, respectively), followed by L. leucocephala (700 kg/ha and 0.5 kg DM/kg LW), L. collinsii (700 kg/ha and 0.4 kg DM/kg LW) and L. trichandra (300 kg/ha and 0.2 kg DM/kg LW). Despite only moderate presentation yields and herbage allowances, steers grazing L. leucocephala and L. collinsii accessions produced the highest mean liveweight gains (LWG) of 0. and 0.56 kg/hd/d, respectively. While L. pallida produced the highest DM yields, it supported the lowest LWG of 0.36 kg/hd/d. The mean LWGs of steers grazing L. trichandra and the control (grass only) treatments were similar at 0.48 kg/ hd/d. The possible reasons for the differences in steer performance on the different Leucaena accessions are discussed.

Animal recognition technology

Murray, P. J. og Finch, N. A. — 2010-03-08T00:00:00Z

Animal welfare and wildlife care

Tribe, A. og Hanger, J — 2007-08-24T00:00:00Z

ANIM2012 Animal Husbandry Introductory Book

Hohenhaus, M.A. — 2007-08-10T00:00:00Z

ANIM2012 Animal Husbandry Study Book

Hohenhaus, M.A. — 2007-08-10T00:00:00Z

An improved embryo-rescue protocol for a Carica interspecific hybrid

2011-03-10T00:00:00Z

An improved experimental model for understanding the impact of sperm DNA fragmentation on human pregnancy following ICSI

2012-11-15T11:08:19Z

Using donor oocytes of proven fertility, the effect of sperm DNA fragmentation (SDF) and motility on reproductive success was examined in 70 couples undergoing ICSI. Both SDF and sperm motility were assessed at the time of sperm injection and using the same sperm sample that was processed for ICSI. While there was no difference in the fertilization rate, cleavage rate, embryo quality, or sperm motility between pregnant and nonpregnant couples, the SDF of nonpregnant couples (SDF = 23.9%) was higher than that of pregnant couples (SDF = 17.0%; U Mann-Whitney 347; P =.002). Using a combination of the sensitivity and specificity measures from the production of ROC (receiver-operating characteristic) curves and the Youden index, we determined a threshold SDF value for our data set of 17% for predicting pregnancy (77.8% sensitivity and 71.1% specificity). Our results suggest that proven donor oocytes in combination with SDF assessment at the time of sperm injection represent a useful experimental model for reducing the confounding influences of sperm DNA repair by the oocyte and iatrogenic sperm damage.

An improved method of microhabitat assessment relevant to predation risk

2010-04-04T00:00:00Z

Animals may select the microhabitats they use in response to a real or perceived risk of attack by visually hunting predators. However, to demonstrate this requires measuring visual cover at the microhabitat level, which can be labor-intensive and may require specialized equipment. Simpler methods lack repeatability, particularly when multiple observers are involved. We devised, and describe here, the quadrant cover method (QCM), which provides rapid, objective assessment of the degree of concealment that microhabitats provide from visual predators. Our method gives results that correlate strongly with those obtained using a conventional sight board, but requires less than 25% of the time. The method is highly repeatable, with negligible observer bias. The QCM is ideal in microhabitat studies in which the variable of interest is visual exposure to other animals such as predators. © The Ecological Society of Japan 2009.

An improved model of nitrogen release for surface-applied controlled-release fertilizer

2012-07-11T00:00:00Z

An improved protocol for somatic embryogenesis in coconut (Cocos nucifera L.)

2011-03-10T00:00:00Z

An insight into the grain auger injury in Queensland, Australia

Athanasiov, A. og Gupta, M L og Fragar, J. — 2007-08-15T00:00:00Z

An integrated systems approach to crop improvement

Hammer, G. L. og Jordan, D. R. — 2011-03-07T00:00:00Z

An intergrated systems approach to crop improvement

Hammer, G. L. og Jordan, D. R. — 2008-05-06T00:00:00Z

An introduction to animal behaviour

Blackshaw, J. K. — 2008-06-10T00:00:00Z

An introduction to community operational research

Midgley, Gerald og Ochoa-Arias, Alejandro E. — 2010-04-08T00:00:00Z

An introduction to Simile

Vanclay, Jerome K. — 2006-06-07T00:00:00Z

This module provides an introduction to Simile, a powerful modelling language with some innovative features. Simile is being developed by Dr Robert Muetzelfeldt, at the University of Edinburgh, with suggestions and testing by a number of users. The package is still under development, so it is getting better all the time, but it is already a sophisticated and stable package. Good documentation is available at http://www.ierm.ed.ac.uk/simile, including some that was prepared when Simile was known by its previous name, AME (Agroforestry Modelling Environment). The latest version of the software can also be downloaded without charge from this Web site, for PCs with Windows 9x or computers running Linux. Dr Muetzelfeldt has long had an interest in efficient representation of ecological information, and his development of Simile was due in part because of his concern that with many models, the documentation, diagrams and computer implementation diverge. So he set out to build a modelling platform where the diagram was the model and the documentation, and he's close to achieving this goal. He's also provided the possibility to create a model that runs on a computer without the need for computer code or mathematical equations. However, there's no free lunch, and it is necessary to learn some of the standard notation used in systems dynamics to be able to use this package. This module provides introduces the systems dynamics notation, and then provides a worked example of developing a Simile model to represent a personal bank account. Some of the unique features of simile are then examined with reference to a simple forestry model. Finally, two other examples of forestry models are presented briefly.

An Introduction to Statistical Package for the Social Sciences

Emtage, Nick F. og Duthy, Stephen — 2006-07-17T00:00:00Z

This module provides an introduction to statistical analysis, particularly in regard to survey data. Some of the features of the Statistical Package for the Social Sciences (SPSS) are then explained, with reference to a farm forestry survey. Of necessity, this is a brief overview to the highly complex and powerful SPSS package.

An investigation into the extent and causes of leucaena toxicity in Queensland

Dalzell, S. A. — 2007-08-14T00:00:00Z

An investigation into the similarities and differences governing the cryopreservation success of koala (Phascolarctos cinereus: goldfuss) and common wombat (Vombatus ursinus: shaw) spermatozoa

2007-08-15T00:00:00Z

The aim of this study was to determine the relative cryopreservation success of koala and wombat spermatozoa and to investigate reasons for their respective post-thaw survival by examining the sperm's response to a range of osmotic media and determining the presence and distribution of F-actin. An hypothesis was proposed that F-actin may be imparting a degree of structural inflexibility to the koala sperm plasma membrane; hence, exposure of spermatozoa to cytochalasin D (5 mu M), a F-actin depolymerisation agent, should result in increased plasticisation of the membrane and greater tolerance of cell volume changes that typically occur during cryopreservation. In experiment 1, koala (n = 4) and wombat (n = 4) spermatozoa packaged in 0.25 mL straws were cryopreserved using two freezing rates (fast-3 cm above liquid N2 interface; slow-6 degrees C/min in a freezing chamber) and two glycerol concentrations (8 and 14% v/v) in a tris-citrate glucose buffer with 15% (v/v) egg yolk. Wombat spermatozoa showed better (P < 0.01) post-thaw survival (% motile, % intact plasma membranes, % decondensed sperm heads) than koala spermatozoa. When exposed to media of varying osmolality, koala spermatozoa were less tolerant (% intact plasma membrane) of hyper-osmotic conditions (920 and 1410mOsmol/kg) than wombat spermatozoa. F-actin was localised using a monoclonal antibody but only found in the wombat sperm head. When koala and wombat spermatozoa were exposed to media of varying osmolality, cytochalasin D had no beneficial effect on sperm survival (% intact plasma membranes). This study has demonstrated that wombat spermatozoa are highly tolerant of cryopreservation when compared to koala sperm but that spermatozoa from both species show greatest post-thaw survival when frozen slowly in 14% glycerol. Koala sperm are also particularly susceptible to hyper-osmotic environments but lack of detectable F-actin in the koala spermatozoan suggests that poor cryopreservation success in this species is unlikely to be associated with F-actin induced plasma membrane inflexibility. (c) 2006 Elsevier Inc. All rights reserved.

An Investigation of Variable Relationships in 3-SAT Problems

2007-10-17T00:00:00Z

To date, several types of structure for finite Constraint Satisfaction Problems have been investigated with the goal of either improving the performance of problem solvers or allowing efficient problem solvers to be identified. Our aim is to extend the work in this area by performing a structural analysis in terms of variable connectivity for 3-SAT problems. Initially structure is defined in terms of the compactness of variable connectivity for a problem. Using an easily calculable statistic developed to measure this compactness, a test was then created for identifying 3-SAT problems as either compact, loose or unstructured (or uniform). A problem generator was constructed for generating 3-SAT problems with varying degrees of structure. Using problems from this problem generator and existing problems from SATLIB, we investigated the effects of this type of structure on satisfiability and solvability of 3-SAT problems. For the same problem length, it is demonstrated that satisfiability and solvability are different for structured and uniform problems generated by the problem generator.

An in vitro assay of the degradative activity of a fibrolytic enzyme against various feed substrates

2007-08-23T00:00:00Z

An in vitro cultured rumen inoculum improves nitrogen digestion in mulga-fed sheep

2009-11-17T00:00:00Z

Mixed cultures of anaerobic micro-organisms were derived from feral goat rumen fluid (FGRF) using a laboratory fermentor to selectively culture microbes actively degrading mulga, and were evaluated as rumen inocula in digestion and liveweight studies with mulga-fed sheep. When placed in the rumen of sheep, FGRF enhances mulga digestion; however, limited supplies of feral goats, the labour involved in locating and mustering goats, and likely variations in the microbial composition of FGRF between animals and localities make the production of an in vitro cultured inoculum a desirable alternative to enable widespread adoption. The cultured inoculum significantly (P < 0·05) improved nitrogen digestion and retention in mulga-fed sheep by 16 and 76%, respectively. Inocula consisting of simplified mixtures of bacteria isolated from sheep, feral goats, and native marsupials did not affect mulga digestion. In the first of 2 liveweight studies, sheep inoculated with the fermentor inoculum lost significantly less weight than uninoculated sheep for the first 57 days (0·3 v. 4·6 kg); however, after 83 days the difference in the rate of liveweight loss between the fermentor inoculum group and the uninoculated sheep was not significant (53 v. 95 g/day). In the second study, liveweight loss was not significantly reduced by the fermentor inoculum. An inoculum based on FGRF, and produced in vitro using a fermentor, is potentially valuable to grazing enterprises reliant on mulga-fed sheep. However, problems in generating a consistent inoculum need to be addressed before such an inoculum can be generally considered.

An in vitro fermented inoculum improves nitrogen digestion in mulga (Acacia aneura) fed sheep

2009-11-19T00:00:00Z

An irradiation marker for mango seed weevil

2008-06-06T00:00:00Z

Anisakid nematodes from stranded pygmy sperm whales, Kogia breviceps (Kogiidae), in three localities of the Yucatan Peninsula, Mexico

2007-08-15T00:00:00Z