916 research outputs found
Evidence for frequent incest in a cooperatively breeding mammal.
As breeding between relatives often results in inbreeding depression, inbreeding avoidance is widespread in the animal kingdom. However, inbreeding avoidance may entail fitness costs. For example, dispersal away from relatives may reduce survival. How these conflicting selection pressures are resolved is challenging to investigate, but theoretical models predict that inbreeding should occur frequently in some systems. Despite this, few studies have found evidence of regular incest in mammals, even in social species where relatives are spatio-temporally clustered and opportunities for inbreeding frequently arise. We used genetic parentage assignments together with relatedness data to quantify inbreeding rates in a wild population of banded mongooses, a cooperatively breeding carnivore. We show that females regularly conceive to close relatives, including fathers and brothers. We suggest that the costs of inbreeding avoidance may sometimes outweigh the benefits, even in cooperatively breeding species where strong within-group incest avoidance is considered to be the norm
Patients Receiving Palliative Care and Their Families' Experiences of Participating in a "Patient-Centered Family Meeting": A Qualitative Substudy of the Valuing Opinions, Individual Communication, and Experience Feasibility Trial.
Background: Family meetings are used in palliative care to facilitate discussion between palliative patients, their families, and the clinical team. However, few studies have undertaken qualitative assessment of the impact of family meetings on patients and their families. Objectives: To explore inpatients receiving palliative care and their families' experiences of participation in a patient-centered family meeting ("Meeting"), where the patient sets the Meeting agenda. Design: This qualitative study used the constant comparative method for thematic content analysis of the data. Setting/Participants: The setting was a specialist palliative care (SPC) inpatient unit in Australia. Nine palliative care inpatients and nine family members were interviewed. Measurements: Semistructured interviews were used evaluate the patients' and their families' experiences and perceptions of the Meeting. Results: Three overarching themes described the experiences of participating in a patient-focused family meeting, namely that the Meeting: (1) provides a forum for inpatients receiving SPC to speak openly about their end-of-life concerns, clarify issues, and is of comfort to patients; (2) provides the family members with a voice, and an opportunity to discuss their concerns and have their needs addressed; and (3) helps to ensure that everyone is "on the same page" and patient care plans can be discussed. Conclusions: These Meetings are a potentially effective means of supporting certain palliative care patients and their families to articulate, confront, and address end-of-life issues in the presence of the interdisciplinary team. It is important to undertake further research to further examine the evidence for this Meeting model and to identify the patients and families who would most benefit from this type of Meeting
Sleep disturbances in caregivers of patients with advanced cancer: A systematic review.
© Cambridge University Press 2017. Objective: Sleep disturbances are a common issue for those who provide informal care to someone with a life-limiting condition. The negative consequences of poor sleep are well documented. The purpose of the present study was to determine the sleep patterns of caregivers of patients with advanced cancer. Method: An extensive systematic review of studies reporting empirical sleep data was undertaken in 2015 in accordance with the PRISMA Statement. A total of eight electronic databases were searched, with no date restrictions imposed. Additionally, a search of the bibliographies of the studies identified during the electronic search was conducted. Search terms included: Sleep, insomnia, sleep disturbance, circadian rhythm, caregiver, carer, advanced cancer, palliative cancer, and MESH suggestions. The inclusion criteria required studies to be in English and to report primary qualitative and/or quantitative research that examined sleep in caregivers of patients with advanced cancer. Unpublished studies, conference papers, and dissertations were excluded. Results: Overall, 10 studies met the inclusion criteria and were included in the review. Two major findings emerged from the data synthesis. First, at least 72% of caregivers reported moderate to severe sleep disturbance as measured by the Pittsburgh Sleep Quality Index. Second, objective measurement of caregivers' sleep identified that some caregivers experienced up to a 44% reduction in their total sleep time compared to the recommended eight hours. Significance of Results: Reduction in total sleep time appears to be the biggest issue facing caregivers' sleep. Future studies need to explore the specific factors that cause these sleep disturbances and thus help to identify interventions to optimize sleep
Hybrid active focusing with adaptive dispersion for higher defect sensitivity in guided wave inspection of cylindrical structures
This is an Accepted Manuscript of an article published by Taylor & Francis in Nondestructive Testing and Evaluation on 23/11/2015, available online: https://www.tandfonline.com/doi/full/10.1080/10589759.2015.1093628.Ultrasonic guided wave inspection is widely used for scanning prismatic structures such as pipes for metal loss. Recent research has investigated focusing the sound energy into predetermined regions of a pipe in order to enhance the defect sensitivity. This paper presents an active focusing technique which is based on a combination of numerical simulation and time reversal concept. The proposed technique is empirically validated using a 3D laser vibrometry measurement of the focal spot. The defect sensitivity of the proposed technique is compared with conventional active focusing, time reversal focusing and synthetic focusing through an empirically validated finite element parametric study. Based on the results, the proposed technique achieves approximately 10 dB improvement of signal-to-coherent-noise ratio compared to the conventional active focusing and time reversal focusing. It is also demonstrated that the proposed technique to have an amplitude gain of around 5 dB over synthetic focusing for defects <0.5λs. The proposed technique is shown to have the potential to improve the reliably detectable flaw size in guided wave inspection from 9% to less than 1% cross-sectional area loss.TWI Ltd and the Center for Electronic System Research (CESR) of Brunel University
Hybrid active focusing with adaptive dispersion for higher defect sensitivity in guided wave inspection of cylindrical structures
This is an Accepted Manuscript of an article published by Taylor & Francis in Nondestructive Testing and Evaluation on 23/11/2015, available online: https://www.tandfonline.com/doi/full/10.1080/10589759.2015.1093628.Ultrasonic guided wave inspection is widely used for scanning prismatic structures such as pipes for metal loss. Recent research has investigated focusing the sound energy into predetermined regions of a pipe in order to enhance the defect sensitivity. This paper presents an active focusing technique which is based on a combination of numerical simulation and time reversal concept. The proposed technique is empirically validated using a 3D laser vibrometry measurement of the focal spot. The defect sensitivity of the proposed technique is compared with conventional active focusing, time reversal focusing and synthetic focusing through an empirically validated finite element parametric study. Based on the results, the proposed technique achieves approximately 10 dB improvement of signal-to-coherent-noise ratio compared to the conventional active focusing and time reversal focusing. It is also demonstrated that the proposed technique to have an amplitude gain of around 5 dB over synthetic focusing for defects <0.5λs. The proposed technique is shown to have the potential to improve the reliably detectable flaw size in guided wave inspection from 9% to less than 1% cross-sectional area loss.TWI Ltd and the Center for Electronic System Research (CESR) of Brunel University
EveTAR: Building a Large-Scale Multi-Task Test Collection over Arabic Tweets
This article introduces a new language-independent approach for creating a
large-scale high-quality test collection of tweets that supports multiple
information retrieval (IR) tasks without running a shared-task campaign. The
adopted approach (demonstrated over Arabic tweets) designs the collection
around significant (i.e., popular) events, which enables the development of
topics that represent frequent information needs of Twitter users for which
rich content exists. That inherently facilitates the support of multiple tasks
that generally revolve around events, namely event detection, ad-hoc search,
timeline generation, and real-time summarization. The key highlights of the
approach include diversifying the judgment pool via interactive search and
multiple manually-crafted queries per topic, collecting high-quality
annotations via crowd-workers for relevancy and in-house annotators for
novelty, filtering out low-agreement topics and inaccessible tweets, and
providing multiple subsets of the collection for better availability. Applying
our methodology on Arabic tweets resulted in EveTAR , the first
freely-available tweet test collection for multiple IR tasks. EveTAR includes a
crawl of 355M Arabic tweets and covers 50 significant events for which about
62K tweets were judged with substantial average inter-annotator agreement
(Kappa value of 0.71). We demonstrate the usability of EveTAR by evaluating
existing algorithms in the respective tasks. Results indicate that the new
collection can support reliable ranking of IR systems that is comparable to
similar TREC collections, while providing strong baseline results for future
studies over Arabic tweets
Reproductive competition triggers mass eviction in cooperative banded mongooses
In many vertebrate societies, forced eviction of group members is an important determinant of population structure, but little is known about what triggers eviction. Three main explanations are (1) the reproductive competition hypothesis; (2) the coercion of cooperation hypothesis; and (3) the adaptive forced dispersal hypothesis. The last hypothesis proposes that dominant individuals use eviction as an adaptive strategy to propagate copies of their alleles through a highly structured population. We tested these hypotheses as explanations for eviction in cooperatively breeding banded mongooses (Mungos mungo), using a 16-year dataset on life history, behaviour and relatedness. In this species, groups of females, or mixed-sex groups, are periodically evicted en masse. Our evidence suggests that reproductive competition is the main ultimate trigger for eviction for both sexes. We find little evidence that mass eviction is used to coerce helping, or as a mechanism to force dispersal of relatives into the population. Eviction of females changes the landscape of reproductive competition for remaining males, which may explain why males are evicted alongside females. Our results show that the consequences of resolving within-group conflict resonate through groups and populations to affect population structure, with important implications for social evolution
On the accuracy of language trees
Historical linguistics aims at inferring the most likely language
phylogenetic tree starting from information concerning the evolutionary
relatedness of languages. The available information are typically lists of
homologous (lexical, phonological, syntactic) features or characters for many
different languages.
From this perspective the reconstruction of language trees is an example of
inverse problems: starting from present, incomplete and often noisy,
information, one aims at inferring the most likely past evolutionary history. A
fundamental issue in inverse problems is the evaluation of the inference made.
A standard way of dealing with this question is to generate data with
artificial models in order to have full access to the evolutionary process one
is going to infer. This procedure presents an intrinsic limitation: when
dealing with real data sets, one typically does not know which model of
evolution is the most suitable for them. A possible way out is to compare
algorithmic inference with expert classifications. This is the point of view we
take here by conducting a thorough survey of the accuracy of reconstruction
methods as compared with the Ethnologue expert classifications. We focus in
particular on state-of-the-art distance-based methods for phylogeny
reconstruction using worldwide linguistic databases.
In order to assess the accuracy of the inferred trees we introduce and
characterize two generalizations of standard definitions of distances between
trees. Based on these scores we quantify the relative performances of the
distance-based algorithms considered. Further we quantify how the completeness
and the coverage of the available databases affect the accuracy of the
reconstruction. Finally we draw some conclusions about where the accuracy of
the reconstructions in historical linguistics stands and about the leading
directions to improve it.Comment: 36 pages, 14 figure
Female reproductive competition explains variation in prenatal investment in wild banded mongooses
Female intrasexual competition is intense in cooperatively breeding species where offspring compete locally for resources and helpers. In mammals, females have been proposed to adjust prenatal investment according to the intensity of competition in the postnatal environment (a form of ‘predictive adaptive response’; PAR). We carried out a test of this hypothesis using ultrasound scanning of wild female banded mongooses in Uganda. In this species multiple females give birth together to a communal litter, and all females breed regularly from one year old. Total prenatal investment (size times the number of fetuses) increased with the number of potential female breeders in the group. This relationship was driven by fetus size rather than number. The response to competition was particularly strong in low weight females and when ecological conditions were poor. Increased prenatal investment did not trade off against maternal survival. In fact we found the opposite relationship: females with greater levels of prenatal investment had elevated postnatal maternal survival. Our results support the hypothesis that mammalian prenatal development is responsive to the intensity of postnatal competition. Understanding whether these responses are adaptive requires information on the long-term consequences of prenatal investment for offspring fitness
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