Assessing the performance of brushtail possums (Trichosurus vulpecula) on the Mechner counting procedure.

This study assessed brushtail possums' performance on the Mechner counting procedure. Six brushtail possums were required to produce different Fixed-Ratio (FR) response targets by lever pressing. Their responses provided access to food reinforcement delivered either upon completing the target FR response requirement on a single lever or, in different conditions, on completing the target FR before producing an additional response on a second lever. The mean number of responses on the first lever before switching to the second lever typically occurred just above the target FR response requirement (FR: 4, 8, 16, 32 and 64). The variability in the number of switches between the levers around the target FR decreased from the first 10 days to the last 10 days, indicating an improvement in counting accuracy over sessions. The time to switch between the first and second lever was consistently variable across response requirements suggesting that it is unlikely the possums were using time to predict when to switch levers. This research further supports the use of the Mechner procedure as a method for measuring counting ability in animals and confirms the possibility of numerical competence in a marsupial species.

Criminal justice interventions for preventing radicalisation, violent extremism and terrorism: An evidence and gap map.

Background: Criminal justice agencies are well positioned to help prevent the radicalisation of individuals and groups, stop those radicalised from engaging in violence, and reduce the likelihood of terrorist attacks. This Evidence and Gap Map (EGM) presents the existing evidence and gaps in the evaluation research. Objectives: To identify the existing evidence that considers the effectiveness of criminal justice interventions in preventing radicalisation, violent extremism and terrorism. Search Methods: We conducted a comprehensive search of the academic and grey literature to locate relevant studies for the EGM. Our search locations included the Global Policing Database (GPD), eight electronic platforms encompassing over 20 academic databases, five trial registries and over 30 government and non-government websites. The systematic search was carried out between 8 June 2022 and 1 August 2022. Selection Criteria: We captured criminal justice interventions published between January 2002 and December 2021 that aimed to prevent radicalisation, violent extremism, and/or terrorism. Criminal justice agencies were broadly defined to include police, courts, and corrections (both custodial and community). Eligible populations included criminal justice practitioners, places, communities or family members, victims, or individuals/groups who are radicalised or at risk of becoming radicalised. Our map includes systematic reviews, randomised controlled trials, and strong quasi-experimental studies. We placed no limits on study outcomes, language, or geographic location. Data Collection and Analysis: Our screening approach differed slightly for the different sources, but all documents were assessed in the systematic review software program DistillerSR on the same final eligibility criteria. Once included, we extracted information from studies using a standardised form that allowed us to collect key data for our EGM. Eligible systematic reviews were assessed for risk of bias using the AMSTAR 2 critical appraisal tool. Main Results: The systematic search identified 63,763 unique records. After screening, there were 70 studies eligible for the EGM (from 71 documents), of which two were systematic reviews (assessed as moderate quality), 16 were randomised controlled trials, and 52 were strong quasi-experimental studies. The majority of studies (n = 58) reported on policing interventions. Limited evidence was found related to courts or corrections interventions. The impact of these interventions was measured by a wide variety of outcomes (n = 50). These measures were thematically grouped under nine broad categories including (1) terrorism, (2) extremism or radicalisation, (3) non-terror related crime and recidivism, (4) citizen perceptions/intentions toward the criminal justice system and government, (5) psychosocial, (6) criminal justice practitioner behaviours/attitudes/beliefs, (7) racially targeted criminal justice practices, (8) investigation efficacy, and (9) organisational factors. The most commonly assessed outcomes included measures of terrorism, investigation efficacy, and organisational factors. Very limited research assessed intervention effectiveness against measures of extremism and/or radicalisation. Authors' Conclusions: Conducting high-quality evaluation research on rare and hidden problems presents a challenge for criminal justice research. The map reveals a number of significant gaps in studies evaluating criminal justice responses to terrorism and radicalisation. We conclude that future research should focus attention on studies that consolidate sound measurement of terrorism-related outcomes to better capture the potential benefits and harms of counter-terrorism programs, policies and practices which involve criminal justice agencies.

Expression of key retinoic acid modulating genes suggests active regulation during development and regeneration of the amphibian limb.

We have previously shown differential regulation of components of the Retinoic acid (RA) pathway in Xenopus tadpole hindlimb regeneration. RA is thought to act as a morphogen, providing positional information during development and regeneration. We have investigated the regulation of genes involved in RA synthesis, catabolism, and binding in developing and regenerating Xenopus limbs. Our data indicate that RA is synthesised by Raldh2 in proximal cells during limb bud outgrowth. Furthermore, Cyp26b is expressed transiently in the progress zone of developing limbs and the blastema of regenerating limbs suggesting degradation of RA occurs in both processes. The RA-binding protein Crabp2 is also upregulated during regeneration. We summarise this data to predict the presence of evolving gradients of RA in the developing amphibian limb. Thus, RA from the stump cells could be responsible for the establishment of proximal-distal pattern during limb regeneration, as predicted by classical studies.

Generalization of learned variability across multiple dimensions in humans.

This study examined whether trained variability would generalize across dimensions of the target response. Two experiments used a computerized rectangle drawing task that required participants to click and drag a mouse cursor to create rectangles on a computer screen. In Experiment 1, one group received points when successive rectangles varied in their size, shape and location (VAR), another group were yoked to the VAR group and received points that were allocated to them using a yoking procedure (YOKE), regardless of the variability in the size, shape or location of the rectangle drawn. Variability was higher for a dimension when variability on that dimension was directly reinforced. In Experiment 2, three groups of participants received points when rectangles varied on two dimensions; each group differed in the two dimensions that required variation. Variability was again higher for the reinforced dimensions for two of the three groups. Comparison with the YOKE group showed that the variability on those dimensions where variability was not directly reinforced was affected by reinforcement for variability on the other dimensions. Specifically, the variability in Shape and Location was significantly higher when these two dimensions occurred with other dimensions where variability was reinforced (as in Experiment 2) compared to when they were not required to vary (as in the YOKE group). This suggests that, for these two groups, the reinforced variability on the other two dimensions generalized to the third dimension. Implications of this finding to our understanding of factors that promote behavioral variability are discussed.

Weber's Law and the Scalar Property of Timing: A Test of Canine Timing.

Domestic dogs completed a temporal bisection procedure that required a response to one lever following a light stimulus of short duration and to another lever following a light stimulus of a longer duration. The short and long durations across the four conditions were (0.5-2.0 s, 1.0-4.0 s, 2.0-8.0 s, and 4.0-16.0 s). Durations that were intermediate, the training durations, and the training durations, were presented during generalization tests. The dogs bisected the intervals near the geometric mean of the short and long-stimulus pair. Weber fractions were not constant when plotted as a function of time: A U-shaped function described them. These results replicate the findings of previous research reporting points of subjective equality falling close to the geometric mean and also confirm recent reports of systematic departures from Weber's law.

Reinforcer quality matters: A test of the Mathematical Principles of Reinforcement with domestic hens (Gallus gallus domesticus).

This study evaluated the ability of Killeen's (1994) Mathematical Principles of Reinforcement to account for the effects of changes in reinforcer quality on hens' rates of responding on fixed-ratio schedules. Hens were trained to peck a key on a fixed-ratio schedule of reinforcement and then experienced an ascending series of ratio values in two separate conditions. In different conditions, the food reinforcer was either wheat or puffed wheat. Response rates initially increased with increases in ratio requirement before eventually decreasing at larger ratios. Quantitative fits of the model accounted for the data well. The fits revealed that different foods were systematically associated with changes in the specific activation parameter, a, and these were consistent with previous reports of preference for those food items.

Co-occurrences of parasite clones and altered host phenotype in a snail-trematode system.

The frequent co-occurrence of two or more genotypes of the same parasite species in the same individual hosts has often been predicted to select for higher levels of virulence. Thus, if parasites can adjust their level of host exploitation in response to competition for resources, mixed-clone infections should have more profound impacts on the host. Trematode parasites are known to induce a wide range of modifications in the morphology (size, shell shape or ornamentation) of their snail intermediate host. Still, whether mixed-clone trematode infections have additive effects on the phenotypic alterations of the host remains to be tested. Here, we used the snail Potamopyrgus antipodarum-infected by the trematode Coitocaecum parvum to test for both the general effect of the parasite on host phenotype and possible increased host exploitation in multi-clone infections. Significant differences in size, shell shape and spinosity were found between infected and uninfected snails, and we determined that one quarter of naturally infected snails supported mixed-clone infections of C. parvum. From the parasite perspective, this meant that almost half of the clones identified in this study shared their snail host with at least one other clone. Intra-host competition may be intense, with each clone in a mixed-clone infection experiencing major reductions in volume and number of sporocysts (and consequently multiplication rate and cercarial production) compared with single-clone infections. However, there was no significant difference in the intensity of host phenotype modifications between single and multiple-clone infections. These results demonstrate that competition between parasite genotypes may be strong, and suggest that the frequency of mixed-clone infections in this system may have selected for an increased level of host exploitation in the parasite population, such that a single-clone is associated with a high degree of host phenotypic alteration.

Demonstration of the scalar property of timing with possums (Trichosurus vulpecula).

Many diverse species have demonstrated interval timing, the ability to respond appropriately to time in the range of seconds to minutes, suggesting that an ability to time is adaptive. The peak procedure is a common method of studying interval time perception. In the peak procedure, animals experience a mix of fixed-interval (FI) and extinction (EXT) trials. On EXT trials, responding typically increases to a peak at the time the FI schedule would normally deliver reinforcers before decreasing. Responding on different FI schedules within the peak procedure has been found to conform to Weber's law, whereby response variability is proportional to the length of the fixed interval. We conducted possibly the first investigation of the timing abilities of a marsupial common to Australia and New Zealand, the brushtail possum (Trichosurus vulpecula), using FI 15-, 30-, and 60-s schedules of reinforcement in the peak procedure. Response rates on EXT trials peaked at the time of usual reinforcer delivery, decreasing at longer time intervals, and were well fit by 3-parameter Gaussian curves, demonstrating the ability of possums to respond to time-based stimuli. Coefficients of variation suggested that the ability of possums to time was less accurate than that of mammals, but similar to that of birds, invertebrates, and reptiles. Coefficients of variation did not differ consistently over increasing FI intervals, showing that timing responses of possums likely conforms to the scalar property of timing also shown by other species. (PsycINFO Database Record

Effect of stimulus and response separation in a matching-to-sample task in the brushtail possum (Trichosurus vulpecula).

This study seeks to investigate the impact of changing the proximity of stimulus and response manipulanda on matching-to-sample performance in possums. Possums were presented with five rows of blue and yellow stimuli arranged vertically 25mm apart above response levers. Generally, peak performance occurred at the distance from the lever currently being trained. Performance generalized to distances close to the currently trained distance and decreased in accuracy at distances further from the trained level. The findings from this experiment provide evidence for placing stimuli and response manipulanda close together to improve acquisition of a task, and increase the responding accuracy in MTS experiments. This suggests that spatial contiguity in the relative location of stimuli and response manipulanda is critical to animals performing complex operant tasks.

Gremlin1 induces anterior-posterior limb bifurcations in developing Xenopus limbs but does not enhance limb regeneration.

Gremlin1 (grem1) has been previously identified as being significantly up-regulated during regeneration of Xenopus laevis limbs. Grem1 is an antagonist of bone morphogenetic proteins (BMPs) with a known role in limb development in amniotes. It forms part of a self-regulating feedback loop linking epithelial (FGF) and mesenchymal (shh) signalling centres, thereby controlling outgrowth, anterior posterior and proximal distal patterning. Spatiotemporal regulation of the same genes in developing and regenerating Xenopus limb buds supports conservation of this mechanism. Using a heat shock inducible grem1 (G) transgene to created temperature regulated stable lines, we have shown that despite being upregulated in regeneration, grem1 overexpression does not enhance regeneration of tadpole hindlimbs. However, both the regenerating and contralateral, developing limb of G transgenics developed skeletal defects, suggesting that overexpressing grem1 negatively affects limb patterning. When grem1 expression was targeted earlier in limb bud development, we saw dramatic bifurcations of the limbs resulting in duplication of anterior posterior (AP) pattern, forming a phenotypic continuum ranging from duplications arising at the level of the femoral head to digit bifurcations, but never involving the pelvis. Intriguingly, the original limbs have AP pattern inversion due to de-restricted Shh signalling. We discuss a possible role for Grem1 regulation of limb BMPs in regulation of branching pattern in the limbs.

Use of a high-sensitivity troponin T assay in the assessment and disposition of patients attending a tertiary Australian emergency department: a cross-sectional pilot study.

OBJECTIVE: We examined the disposition and outcomes of patients presenting to the ED with symptoms suggestive of acute coronary syndrome undergoing measurement of troponin T using a highly sensitive assay. METHODS: Troponin T (TnT) was measured in 204 consecutive patients (mean age = 65 [±18] years, 55% men) presenting to the ED with symptoms suggestive of acute coronary syndrome. RESULTS: Ninety-four patients predominantly had chest pain, 34 had dyspnoea and the remainder had various symptoms. Overall, 96 patients had TnT >14 ng/L (upper reference limit), of whom 31 were admitted to the cardiology service (26 had final cardiac diagnosis [five ST-elevation MI, 10 non-ST-elevation MI, one unstable angina and 10 other cardiac]). Among these 96 patients, 41 had chronic kidney disease, 17 had heart failure and seven had sepsis. At 30 days, death rates among patients who had TnT >14 ng/L with non-cardiac diagnoses and in patients who had TnT >14 ng/L with a cardiac diagnosis were 6.6% and 2.9% (P = 0.652); no death and/or MI occurred in patients with normal TnT levels. At late follow up (median 6.8 months) that was obtained in 189 (93% of 204) patients, four had MI and 14 died (three cardiac deaths). CONCLUSIONS: Despite high-sensitivity TnT assay having a high sensitivity and specificity for myocardial necrosis, the majority of unselected consecutive patients attending ED in whom TnT levels were elevated did not have an acute coronary syndrome. Our pilot study suggests that a larger study is needed to provide evidence to modify management algorithms.

Analysis of the expression of retinoic acid metabolising genes during Xenopus laevis organogenesis.

Retinoic acid (RA) is a known teratogen that is also required endogenously for normal development of the embryo. RA can act as a morphogen, through direct binding to receptors and RA response elements in the genome, and classical studies of limb development and regeneration in amphibians have shown that it is likely to provide positional information. Availability of RA depends on both metabolic synthesis and catabolic degradation, and specific binding proteins act to further modulate the binding of RA to response elements. Here, we describe the expression of seven genes involved in metabolism (Raldh1-3), catabolism (Cyp26a and b) and binding of RA (Crabp1 and 2) during organogenesis in the clawed frog Xenopus laevis. Taken together, this data indicates regions of the embryo that could be affected by RA mediated patterning, and identifies some differences with other vertebrates.