159 research outputs found

    Constellations and their relationship with categories

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    Constellations are partial algebras that are one-sided generalisations of categories. Indeed, we show that a category is exactly a constellation that also satisfies the left-right dual axioms. Constellations have previously appeared in the context of inductive constellations: the category of inductive constellations is known to be isomorphic to the category of left restriction semigroups. Here we consider constellations in full generality, giving many examples. We characterise those small constellations that are isomorphic to constellations of partial functions. We examine in detail the relationship between constellations and categories. In particular, we characterise those constellations that arise as (sub-)reducts of categories. We demonstrate that the notion of substructure can be captured within constellations but not within categories. We show that every constellation P gives rise to a category (Formula presented.), its canonical extension, in a simplest possible way, and that P is a quotient of (Formula presented.) in a natural sense. We also show that many of the most common concrete categories may be constructed from simpler quotient constellations using this construction. We characterise the canonical congruences (Formula presented.) on a given category (Formula presented.) (those for which (Formula presented.), and show that the category of constellations is equivalent to the category of (Formula presented.)-categories, that is, categories equipped with distinguished canonical congruence (Formula presented.). The main observation of this paper is that category theory as it applies to the familiar concrete categories of modern mathematics (which come equipped with natural notions of substructures and indeed are (Formula presented.)-categories) may be subsumed by constellation theory

    Assessing victim risk in cases of violent crime

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    Purpose: There is a body of evidence that suggests a range of psychosocial characteristics demarcate certain adults to be at an elevated risk for victimisation. To this end, the aim of the current study was to examine consistency between one police force, and a corresponding victim support service based in England, in their assessment of level of risk faced by victims of violent crime. Methodology: This study explored matched data on 869 adult victims of violent crime gathered from these two key services in Preston, namely Lancashire Constabulary and Victim Support, from which a sub-group of comparable ā€˜domestic violenceā€™ cases (n=211) were selected for further examination. Findings: Data analyses revealed methodological inconsistencies in the assessment of victimisation resulting in discrepancies for recorded levels of risk in domestic violence cases across these two agencies. Practical implications: These findings provide a compelling argument for developing a more uniformed approach to victim assessment and indicate a significant training need. Value: This paper highlights areas of good practice and forwards several recommendations for improved practice that emphasises the integration of empirical research conducted by psychologists to boost the validity and reliability of risk assessment approaches and tools used

    Repeat Victimisation, Retraumatisation and Victim Vulnerability

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    Abstract: This study explores the contribution that traumatic experiences and psychological post-traumatic stress symptoms make to predicting subsequent revictimisation in a sample of violent crime victims. In addition, the timing of first trauma exposure was also explored. Fifty-four adult victims (27 male and 27 female) of police recorded violent crime were interviewed and their traumatic exposure history, trauma symptomology, age at first trauma exposure as well as psychological and psychosocial functioning were assessed. These victims were followed longitudinally and subsequent revictimisation between six and twelve months post index victimisation measured. A greater number of types of trauma exposure was related lower emotional stability, higher trauma symptomology and revictimisation. Those victims with childhood traumatic exposure reported more trauma symptomology exposure than those without prior exposure. The implications for law enforcement and victim services are discussed

    Adrenal insufficiency in acute oral opiate therapy

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    UNLABELLED: Opiate drugs such as morphine are in extensive use for pain relief and palliation. It is well established that these drugs can cause changes in endocrine function, but such effects are not always sufficiently appreciated in clinical practice, especially in relation to the hypothalamic-pituitary-adrenal (HPA) axis. Herein, we report on an 18-year-old man who was diagnosed with a slipped left femoral epiphysis following a long history of pain in his leg. On examination, he was thought to look relatively young for his age and therefore the orthopaedic surgeons arranged an endocrine assessment, which showed an undetectable concentration of serum cortisol and a suppressed concentration of testosterone; therefore, he was referred urgently with a diagnosis of hypopituitarism. We elicited a history that he had been treated with opiate analgesics for 3 days at the time of his original blood tests. Full endocrine assessment including a short Synacthen test revealed that he now had normal adrenal and pituitary function. We conclude that his morphine therapy had caused profound suppression of his HPA and pituitary-gonadal axes and suggest that clinicians should be aware of these significant changes in patients on even short-term opiate therapy. LEARNING POINTS: Therapy with opiates is the standard therapy for severe acute and chronic pain.Such drugs cause profound changes in endocrine function.Importantly, opiates suppress the HPA axis at a central level.Short-term therapy with morphine could be the cause of biochemical adrenocortical insufficiency.Morphine and related drugs also suppress the pituitary-gonadal axis.After discontinuation of therapy with such drugs, adrenal function improves

    Predictors of engagement with support services in a sample of UK victims of violent crime.

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    Research suggests that engagement with support services after criminal victimisation is low. With this in mind, this study investigated predictors of engagement with Victim Support, in a sample of victims of violent crime. All violent crimes recorded by Lancashire Constabulary for two postcode areas (PR1 and PR2), who were referred to Victim Support (Preston) between April 2013 and September 2013 (n=869) were assessed, with a follow-up undertaken in 2014. Two percent of victims booked or attended a face-to-face meeting with Victim Support, and just over one fifth engaged over the telephone on at least one occasion across a range of support options at the initial data collection point. Engagement with Victim Support was not significantly related to future victimisation. When revictimisation since the first data collection period was inspected against demographic and crime-related variables, previous victimisation, regardless of the type of crime experienced, was the strongest predictor of being victimised again. This was despite the fact that such victims were more likely to be identified as high risk, and actively engaged with Victim Support at the initial time of victimisation. Suggestions for further research are made in light of the changes generally to victim services in the UK

    Experimental and computation assessment of thermomechanical effects during auxetic foam fabrication

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    Auxetic foams continue to interest researchers owing to their unique and enhanced properties. Existing studies attest to the importance of fabrication mechanisms and parameters. However, disparity in thermo-mechanical parameters has left much debate as to which factors dominate fabrication output quality. This paper provides experimental, computational, and statistical insights into the mechanisms that enable auxetic foams to be produced, using key parameters reported within the literature: porosity; heating time; and volumetric compression ratio. To advance the considerations on manufacturing parameter dominance, both study design and scale have been optimised to enable statistical inferences to be drawn. Whilst being unusual for a manufacturing domain, such additional analysis provides more conclusive evidence of auxetic properties and highlights the supremacy of volumetric compression ratio in predicting Poissonā€™s ratio outcomes in the manufacture process. Furthermore statistical results are exploited to formulate key recommendations for those wishing to maximise/optimise auxetic foam production

    Control of PTH secretion by the TRPC1 ion channel

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    Familial Hypocalciuric Hypercalcemia (FHH) is a genetic condition associated with hypocalciuria, hypercalcemia and in some cases inappropriately high levels of circulating parathyroid hormone (PTH). FHH is associated with inactivating mutations in CaSR encoding the Ca2+ sensing receptor (CaSR), a G protein coupled receptor (GPCR) and GNA11 encoding G protein subunit alpha 11 (GĪ±11), implicating defective GPCR signaling as the root pathophysiology for FHH. However, the downstream mechanism by which CaSR activation inhibits PTH production/secretion is incompletely understood. Here, we show that mice lacking the transient receptor potential canonical channel 1 (TRPC1) develop chronic hypercalcemia, hypocalciuria, and elevated PTH levels mimicking human FHH. Ex vivo and in vitro studies reveal that TRPC1 serves a necessary and sufficient mediator to suppress PTH secretion from parathyroid glands (PTG) downstream of CaSR in response to high extracellular Ca2+ concentration. GĪ±11 physically interacts with both the N- and C-termini of TRPC1 and enhances CaSR-induced TRPC1 activity in transfected cells. These data identify TRPC1-mediated Ca2+ signaling as an essential component of the cellular apparatus controlling PTH secretion in the PTG downstream of CaSR
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