7440 research outputs found
Sort by
Making a queen : an epigenetic analysis of the robustness of the honeybee (Apis mellifera) queen developmental pathway
No full textSpecialized castes are considered a key reason for the evolutionary and ecological success of the social insect lifestyle. The most essential caste distinction is between the fertile queen and the sterile workers. Honeybee (Apis mellifera) workers and queens are not genetically distinct, rather these different phenotypes are the result of epigenetically regulated divergent developmental pathways. This is an important phenomenon in understanding the evolution of social insect societies. Here, we studied the genomic regulation of the worker and queen developmental pathways, and the robustness of the pathways by transplanting eggs or young larvae to queen cells. Queens could be successfully reared from worker larvae transplanted up to 3 days age, but queens reared from older worker larvae had decreased queen body size and weight compared with queens from transplanted eggs. Gene expression analysis showed that queens raised from worker larvae differed from queens raised from eggs in the expression of genes involved in the immune system, caste differentiation, body development and longevity. DNA methylation levels were also higher in 3-day-old queen larvae raised from worker larvae compared with that raised from transplanted eggs identifying a possible mechanism stabilizing the two developmental paths. We propose that environmental (nutrition and space) changes induced by the commercial rearing practice result in a suboptimal queen phenotype via epigenetic processes, which may potentially contribute to the evolution of queen–worker dimorphism. This also has potentially contributed to the global increase in honeybee colony failure rates.10 page(s
Extensive genetic differentiation detected within a model marsupial, the tammar wallaby (Notamacropus eugenii)
No full textThe tammar wallaby (Notamacropus eugenii) is one of the most intensively studied of all macropodids and was the first Australasian marsupial to have its genome sequenced. However, comparatively little is known about genetic diversity and differentiation amongst the morphologically distinct allopatric populations of tammar wallabies found in Western (WA) and South Australia (SA). Here we compare autosomal and Y-linked microsatellite genotypes, as well as sequence data (~600 bp) from the mitochondrial DNA (mtDNA) control region (CR) in tammar wallabies from across its distribution. Levels of diversity at autosomal microsatellite loci were typically high in the WA mainland and Kangaroo Island (SA) populations (A = 8.9-10.6; He = 0.77-0.78) but significantly reduced in other endemic island populations (A = 3.8-4.1; He = 0.41-0.48). Autosomal and Y-linked microsatellite loci revealed a pattern of significant differentiation amongst populations, especially between SA and WA. The Kangaroo Island and introduced New Zealand population showed limited differentiation. Multiple divergent mtDNA CR haplotypes were identified within both SA and WA populations. The CR haplotypes of tammar wallabies from SA and WA show reciprocal monophyly and are highly divergent (14.5%), with levels of sequence divergence more typical of different species. Within WA tammar wallabies, island populations each have unique clusters of highly related CR haplotypes and each is most closely related to different WA mainland haplotypes. Y-linked microsatellite haplotypes show a similar pattern of divergence although levels of diversity are lower. In light of these differences, we suggest that two subspecies of tammar wallaby be recognized; Notamacropus eugenii eugenii in SA and N. eugenii derbianus in WA. The extensive neutral genetic diversity and inter-population differentiation identified within tammar wallabies should further increase the species value and usefulness as a model organism.23 page(s
A Computational model of the integration of landmarks and motion in the insect central complex
No full textThe insect central complex (CX) is an enigmatic structure whose computational function has evaded inquiry, but has been implicated in a wide range of behaviours. Recent experimental evidence from the fruit fly (Drosophila melanogaster) and the cockroach (Blaberus discoidalis) has demonstrated the existence of neural activity corresponding to the animal's orientation within a virtual arena (a neural 'compass'), and this provides an insight into one component of the CX structure. There are two key features of the compass activity: an offset between the angle represented by the compass and the true angular position of visual features in the arena, and the remapping of the 270° visual arena onto an entire circle of neurons in the compass. Here we present a computational model which can reproduce this experimental evidence in detail, and predicts the computational mechanisms that underlie the data. We predict that both the offset and remapping of the fly's orientation onto the neural compass can be explained by plasticity in the synaptic weights between segments of the visual field and the neurons representing orientation. Furthermore, we predict that this learning is reliant on the existence of neural pathways that detect rotational motion across the whole visual field and uses this rotation signal to drive the rotation of activity in a neural ring attractor. Our model also reproduces the 'transitioning' between visual landmarks seen when rotationally symmetric landmarks are presented. This model can provide the basis for further investigation into the role of the central complex, which promises to be a key structure for understanding insect behaviour, as well as suggesting approaches towards creating fully autonomous robotic agents.19 page(s
Body image and psychological distress in nipple-sparing mastectomy : the roles of self-compassion and appearance investment
No full textObjective: Women with breast cancer face threats to body image following surgery. Nipple-sparing mastectomy with immediate breast reconstruction (NSM + IBR) may minimise body image disturbance as this preserves the woman's skin and areola complex. We assessed levels of body image disturbance and psychological distress in women undergoing NSM + IBR. To further understand the body image–distress relationship, we investigated the potential moderating effect of self-compassion and appearance investment on this relationship. Methods: Women diagnosed with breast cancer (N = 75) who had undergone NSM + IBR completed online questionnaires including the Body Image Scale, general (Depression, Anxiety and Stress Scales) and cancer-specific (Impact of Event Scale) psychological distress and Self-Compassion Scale and Appearance Schemas Inventory – Revised. Results: Mean general and cancer-specific psychological distress scores were within normal ranges, and body image disturbance was moderately low. Body image was positively correlated with depression, stress, Impact of Event Scale scores and appearance investment and negatively correlated with self-compassion. MANCOVA analyses indicated a significant moderating effect of self-compassion and appearance investment on the body image disturbance–distress relationship (for depression, stress and intrusion), such that participants with high self-compassion and low appearance investment experienced lower distress than individuals with low self-compassion and high appearance investment. Conclusions: Moderately low levels of psychological distress and body image disturbance suggest NSM + IBR may minimise adverse psychological impacts of mastectomy. Increased body image disturbance was associated with psychological distress and moderated by self-compassion and appearance investment, suggesting a potential role for these characteristics as the focus of psychological interventions to minimise the negative impacts of mastectomy.9 page(s
Internet-delivered parenting program for prevention and early intervention of anxiety problems in young children : randomized controlled trial
No full textObjective: The Cool Little Kids parenting group program is an effective intervention for preventing anxiety disorders in young children who are at risk because of inhibited temperament. The program has six group sessions delivered by trained psychologists to parents of 3- to 6-year-old children. An online adaptation (Cool Little Kids Online) has been developed to overcome barriers to its wide dissemination in the community. This study tested the efficacy of Cool Little Kids Online in a randomized controlled trial. Method: A total of 433 parents of a child aged 3 to 6 years with an inhibited temperament were randomized to the online parenting program or to a 24-week waitlist. The online program has 8 interactive modules providing strategies that parents can implement with their child to manage their child's avoidant coping, reduce parental overprotection, and encourage child independence. Parents were provided telephone consultation support with a psychologist when requested. Parents completed self-report questionnaires at baseline and at 12 and 24 weeks after baseline. Results: The intervention group showed significantly greater improvement over time in child anxiety symptoms compared to the control group (d = 0.38). The intervention group also showed greater reductions in anxiety life interference (ds = 0.33-0.35) and lower rates of anxiety disorders than the control group (40% versus 54%), but there were minimal effects on broader internalizing symptoms or overprotective parenting. Conclusion: Results provide empirical support for the efficacy of online delivery of the Cool Little Kids program. Online dissemination may improve access to an evidence-based prevention program for child anxiety disorders.10 page(s
The power of the literary image: mediating memory and managing emotion in the literary memoirs of Virginia Woolf and Helen Garner
No full textTheoretical thesis.Bibliography: pages 85-92Introduction -- Chapter 1: Portraying and engendering memory in autobiographical narrative -- Chapter 2: The power and potential of emotion in life narratives -- Chapter 3: Empathy in life writing – feeling for our former selves.Despite wide scholarly consensus regarding our long-standing penchant for autobiographical literature, further critical work is needed to more clearly apprehend and articulate the interplay between particular narrative techniques and cognitive processes that combine to invite such enthusiastic readerly engagements with life writing texts. My Master of Research project - focusing specifically on the literary memoir - aims to identify and explicate a number of potent contributing factors that drive and motivate our ongoing readerly predilection for skillfully written autobiographical narratives. This transdisciplinary cognitive literary study examines selected passages from the literary memoirs of Virginia Woolf (1882–1941) ('Moments of Being') and Helen Garner (1942- ('True Stories and Everywhere I Look'). It focuses specifically on textual representations of memory, emotion and empathy, three components crucial not only to both effective and affective portrayals of life narratives, but also to self understanding and the creation of personal narratives beyond writing, in lived experience.1 online resource (92 pages
Watching the pendulum swing: investigating changes in the scope and impact of provisions in investment treaties for securing environmental protection
No full textTheoretical thesis.Bibliography: pages 106-119.Chapter 1. Balancing public and private interests -- Chapter 2. Speaking of ‘environmental’ in investment treaties and trade agreements -- Chapter 3. NAFTA : trend-setter or spoiler for environmental ppprotection -- Chapter 4. The Trans-Pacific Partnership : a step backwards in environmental protection -- Chapter 5. The debate over investor–state dispute settlement : who wins? -- Chapter 6. Conclusion—Is the US leading the world on a race to the bottom? -- Bibliography -- Appendices.With the turn of the century, investment treaties began to address the potential for conflict between the introduction by governments of protective environmental measures and investors’ claims of intereference with their rights to fully exploit their investments, prompting claims for compensation over reduction in the profitability of their investments. This conflict reflects a tension between the public’s right to a safe environment, on the one hand, and investors’ rights on the other. Since the 1990s, this tug-of-war between those supporting investment protection and those advocating for a safe environment has been played out in the case law of courts and arbitral tribunals, as well as in the drafting of investment treaties and free trade agreements. While environmental provisions in recent agreements, such as NAFTA and Trans Pacific Partnership (TPP), have suggested the pendulum is swinging with greater force in the direction of the environment, nevertheless the potential for positive impact on the environment has continued to be hampered by both legal and linguistic expedients that prioritize economic growth over environmental concerns. The Investor-State Dispute Settlement (ISDS) provisions carried over into TPP from NAFTA allow foreign investors to challenge government measures related to environmental, health, and safety regulations which investors claim to violate treaty obligations into which the State willingly entered for investors’ protection. Moreover, with recent calls for the renegotiation of NAFTA and the US decision to withdraw from TPP, it may be the pendulum is swinging back in favour of economic over environmental concerns.Mode of access: World wide web1 online resource (viii, 128 pages) table
Global identification in the cloud: a study of cloud passport model
No full textThesis by publication.Bibliography: 77-84.1. Introduction -- 2. Literature review -- 3. Research philosophy -- 4. Research methodology -- 5. Quantitative result analysis -- 6. Qualitative result analysis -- 7. Discussion of survey results -- 8. Conclusion -- References -- Appendix.In this research, we studied the idea of Cloud Passport, an initiative which uses the latest technologies to replace physical passports. Advantages and challenges of implementing a passport-less system for travel between countries were discussed. Different types of technology adoption models and research method were evaluated. A Cloud Passport adoption model was formulated as the basis for the current research.A convenient sample survey was conducted in February 2017 to Australian adult Facebook users to find out the social attitude on the proposal of Cloud Passport. Survey results showed that there was a 70% acceptance level on Cloud Passport. Social opinions on different technical components of Cloud Passport were also asked in the study. 75% of the interviewees thought that Cloud Passport would be available worldwide in the next 10 to 20 years. A textual analysis of the feedback from the survey discovered some drivers and barriers to the implementation of Cloud Passport.The observations from the surveys formed an overall view of the social opinion of a sample of Australians on the Cloud Passport initiative, which may help to contribute further study for an appropriate change management strategy for a successful roll-out of Cloud Passport in Australia.Mode of access: World wide web1 online resource (xv, 101 pages) colour illustration
Early neural dynamics of visual word recognition
No full textThesis by publication."Department of Cognitive Science, ARC Centre of Excellence in Cognition and its Disorders, Faculty of Human Sciences, Macquarie University, Sydney, Australia" -- title page.Bibliography: pages 159-186.Chapter 1. General introduction -- Chapter 2. Early top-town feedback from frontal to ventral occipito-temporal cortex during visual word recognition -- Chapter 3. Task modulation of early top-down feedback from frontal to ventral occipito-temporal cortex during visual word recognition -- Chapter 4. Task modulation of the time course of visual word recognition -- Chapter 5. General discussion -- References -- Ethics approval.For a skilled reader, visual word recognition can be completed within several hundred milliseconds. There is evidence that the left inferior frontal cortex is activated by visual words in the first 300 ms after stimulus onset; additionally, there is evidence for early top-down feedback from this frontal region to ventral occipito-temporal cortex during visual word recognition. Using magnetoencephalography (MEG), this thesis sought to examine early neural dynamics of visual word recognition by examining the early stage inter-regional connectivity and time course of visual word recognition.In Chapter 1, I review studies of the neural correlates and relevant neural models of visual word recognition; in particular, two models on the ventral occipito-temporal cortex in visual word recognition with contrasting views on the role of top-down feedback are examined. I then introduce dynamic causal modeling (DCM), a crucial neuroimaging method for examining directional influences of one brain area to another. Next I review the neuroimaging studies of visual word recognition focusing on its time course and also highlight the importance of examining early brain activity of visual word recognition. Finally, I propose the research questions to be addressed in this thesis: What is the nature of early top-down feedback from frontal to ventral occipito-temporal cortex during visual word recognition? How task goals modulate the early top-down feedback? How task goals modulate the time course of visual word recognition? These questions are examined in three empirical chapters.Using a semantic categorisation task, Chapter 2 examines the nature of top-down feedback from the left inferior frontal gyrus (LIFG) to the left ventral occipito-temporal cortex (LvOT) during the first 200 ms visual word recognition. The results revealed that the LIFG-to-LvOT connection was stronger for real words than for pseudowords, and stronger for false fonts than for consonant strings in both 1-150 ms and 1-200 ms time-windows, indicating that both lexical-semantic and surface letter information influence early top-down feedback. Furthermore, the LIFG-to-LvOT connection was stronger for pseudowords than for consonant strings in the 1-200 ms time-window, indicating that compared with lexical-semantic and surface letter information, the influences of phonological information occur later.By comparing a non-linguistic visual discrimination task (is it a hash string?) with the semantic categorisation task (is it an animal word?) used in Chapter 2, Chapter 3 examines how task goals modulate the early LIFG-to-LvOT feedback during the first 200 ms visual word recognition. The results revealed that the LIFG-to-LvOT connection was stronger for real words than for pseudowords in both 1-150 ms and 1-200 ms time-windows in the discrimination task, and this was similar to that in the semantic task, indicating that the influences of lexical-semantic information on this feedback are independent of task goals. However, in the discrimination task the LIFG-to-LvOT connection was stronger for consonant strings than for pseudowords in the 1-200 ms time-window and was stronger for consonant strings than for false fonts in the 1-150 ms time-window, and this was opposite to that in the semantic task, indicating that the influences of letter and phonological information on the early feedback are dependent on task goals.Using the data from the previous two chapters, Chapter 4 examines how task goals modulate the on-line time course of visual word recognition by examining the first 500 ms time course data during the linguistic semantic task and the non-linguistic discrimination task. A behavioural version of each MEG experiment with one task is also reported on. The MEG and behavioural results established that an emphasis on high-level linguistic information in a linguistic task sensitise early neural responses to linguistic properties, whereas an emphasis on low-level visual feature detection in a non-linguistic task sensitise early neural responses to physical appearance.This thesis has established that lexical-semantic, phonological, and letter properties all can trigger early top-down feedback during visual word recognition, but occur differently across time. Task goals with different emphases strongly bias early top-down feedback and also modulate the time course of visual word recognition.Mode of access: World wide web1 online resource (vi, 189 pages) : colour illustration
Sentence comprehension in monolingual and bilingual aphasia: evidence from behavioral and eye-tracking methods
No full textEmpirical thesis.Bibliography: pages 165-191.Chapter 1. General introduction -- Chapter 2. Eye-tracking the effect of word order in sentence comprehension in aphasia : evidence from Basque, a free word order ergative language -- Chapter 3. Bilingual aphasia : cross-linguistic asymmetries and lack of bilingual advantage in sentence comprehension deficits -- Chapter 4. What happens when they think they are right? Error awareness analysis of sentence comprehension deficits in aphasia -- Chapter 5. General discussion -- References -- Appendices.The current thesis focuses on sentence processing in people with aphasia (PWA) and non-brain-damaged (NBD) speakers of a free word order language (Basque) and/or a flexible word order language (Spanish). It includes a series of studies on bilingual and monolingual speakers with the goal being to consider a) how language-specific properties influence accuracy and real time processing within sentence comprehension (Chapters 2 and 3); b) the cross-linguistic transferability of sentence parsing mechanisms in bilingual speakers (Chapter 3); c) the potential bilingual advantage in sentence comprehension abilities due to enhancement of executive functions (Chapter 3); and d) self monitoring abilities and consequent error awareness in sentence comprehension (Chapter 4).Mode of access: World wide web1 online resource (214 pages) diagrams, graphs, table