Extremism propagation in social networks with hubs

One aspect of opinion change that has been of academic interest is the impact of people with extreme opinions (extremists) on opinion dynamics. An agent-based model has been used to study the role of small-world social network topologies on general opinion change in the presence of extremists. It has been found that opinion convergence to a single extreme occurs only when the average number of network connections for each individual is extremely high. Here, we extend the model to examine the effect of positively skewed degree distributions, in addition to small-world structures, on the types of opinion convergence that occur in the presence of extremists. We also examine what happens when extremist opinions are located on the well-connected nodes (hubs) created by the positively skewed distribution. We find that a positively skewed network topology encourages opinion convergence on a single extreme under a wider range of conditions than topologies whose degree distributions were not skewed. The importance of social position for social influence is highlighted by the result that, when positive extremists are placed on hubs, all population convergence is to the positive extreme even when there are twice as many negative extremists. Thus, our results have shown the importance of considering a positively skewed degree distribution, and in particular network hubs and social position, when examining extremist transmission

Knowledge-based vision and simple visual machines

The vast majority of work in machine vision emphasizes the representation of perceived objects and events: it is these internal representations that incorporate the 'knowledge' in knowledge-based vision or form the 'models' in model-based vision. In this paper, we discuss simple machine vision systems developed by artificial evolution rather than traditional engineering design techniques, and note that the task of identifying internal representations within such systems is made difficult by the lack of an operational definition of representation at the causal mechanistic level. Consequently, we question the nature and indeed the existence of representations posited to be used within natural vision systems (i.e. animals). We conclude that representations argued for on a priori grounds by external observers of a particular vision system may well be illusory, and are at best place-holders for yet-to-be-identified causal mechanistic interactions. That is, applying the knowledge-based vision approach in the understanding of evolved systems (machines or animals) may well lead to theories and models that are internally consistent, computationally plausible, and entirely wrong

Proteomic profiling of urinary proteins in renal cancer by surface enhanced laser desorption ionisation (SELDI) and neural-network analysis: Identification of key issues affecting potential clinical utility.

Recent advances in proteomic profiling technologies, such as surface enhanced laser desorption ionization mass spectrometry, have allowed preliminary profiling and identification of tumor markers in biological fluids in several cancer types and establishment of clinically useful diagnostic computational models. There are currently no routinely used circulating tumor markers for renal cancer, which is often detected incidentally and is frequently advanced at the time of presentation with over half of patients having local or distant tumor spread. We have investigated the clinical utility of surface enhanced laser desorption ionization profiling of urine samples in conjunction with neural-network analysis to either detect renal cancer or to identify proteins of potential use as markers, using samples from a total of 218 individuals, and examined critical technical factors affecting the potential utility of this approach. Samples from patients before undergoing nephrectomy for clear cell renal cell carcinoma (RCC; n 48), normal volunteers (n 38), and outpatients attending with benign diseases of the urogenital tract (n 20) were used to successfully train neural-network models based on either presence/absence of peaks or peak intensity values, resulting in sensitivity and specificity values of 98.3–100%. Using an initial “blind” group of samples from 12 patients with RCC, 11 healthy controls, and 9 patients with benign diseases to test the models, sensitivities and specificities of 81.8–83.3% were achieved. The robustness of the approach was subsequently evaluated with a group of 80 samples analyzed “blind” 10 months later, (36 patients with RCC, 31 healthy volunteers, and 13 patients with benign urological conditions). However, sensitivities and specificities declined markedly, ranging from 41.0% to 76.6%. Possible contributing factors including sample stability, changing laser performance, and chip variability were examined, which may be important for the long-term robustness of such approaches, and this study highlights the need for rigorous evaluation of such factors in future studies

Beyond persons: extending the personal / subpersonal distinction to non-rational animals and artificial agents

The distinction between personal level explanations and subpersonal ones has been subject to much debate in philosophy. We understand it as one between explanations that focus on an agent’s interaction with its environment, and explanations that focus on the physical or computational enabling conditions of such an interaction. The distinction, understood this way, is necessary for a complete account of any agent, rational or not, biological or artificial. In particular, we review some recent research in Artificial Life that pretends to do completely without the distinction, while using agent-centered concepts all the way. It is argued that the rejection of agent level explanations in favour of mechanistic ones is due to an unmotivated need to choose among representationalism and eliminativism. The dilemma is a false one if the possibility of a radical form of externalism is considered

Symptom burden and lived experiences of patients, caregivers and healthcare professionals on the management of malignant bowel obstruction: A qualitative systematic review

Background: Malignant bowel obstruction occurs in up to 50% of people with advanced ovarian and 15% of people with gastrointestinal cancers. Evaluation and comparison of interventions to manage symptoms are hampered by inconsistent evaluations of efficacy and lack of agreed core outcomes. The patient perspective is rarely incorporated. Aim: To synthesise the qualitative data regarding patient, caregiver and healthcare professionals’ views and experience of malignant bowel obstruction to inform the development of a core outcome set for the evaluation of malignant bowel obstruction. Design: A qualitative systematic review was conducted, with narrative synthesis. The review protocol was registered prospectively (https://www.crd.york.ac.uk/prospero, CRD42020176393). Data sources: MEDLINE, EMBASE, CINAHL, PsycINFO and Scopus databases were searched for studies published between 2010 and 2021. Reference lists were screened for further relevant publications, and citation tracking was performed. Results: Nine papers were included, reporting on seven studies which described the views and experiences of malignant bowel obstruction through the perspectives of 75 patients, 13 caregivers and 62 healthcare professionals. Themes across the papers included symptom burden, diverse experiences of interventions, impact on patient quality of life, implications and trajectory of malignant bowel obstruction, mixed experience of communication and the importance of realistic goals of care. Conclusion: Some of the most devastating sequelae of malignant bowel obstruction, such as pain and psychological distress, are not included routinely in its clinical or research evaluation. These data will contribute to a wider body of work to ensure the patient and caregiver perspective is recognised in the development of a core outcome set

The range and suitability of outcome measures used in the assessment of palliative treatment for inoperable malignant bowel obstruction: A systematic review

Background: Malignant bowel obstruction, a complication of certain advanced cancers, causes severe symptoms which profoundly affect quality of life. Clinical management remains complex, and outcome assessment is inconsistent.Aim: To identify outcomes evaluating palliative treatment for inoperable malignant bowel obstruction, as part of a four-phase study developing a core outcome set. Design: The review is reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA); PROSPERO (ID: CRD42019150648). Eligible studies included at least one subgroup with obstruction below the ligament of Treitz undergoing palliative treatment for inoperable malignant bowel obstruction. Study quality was not assessed because the review does not evaluate efficacy. Data sources: Medline, Embase, the Cochrane Database, CINAHL, PSYCinfo Caresearch, Open Grey and BASE were searched for trials and observational studies in October 2021. Results: A total of 4769 studies were screened, 290 full texts retrieved and 80 (13,898 participants) included in a narrative synthesis; 343 outcomes were extracted verbatim and pooled into 90 unique terms across six domains: physiological, nutrition, life impact, resource use, mortality and survival. Prevalent outcomes included adverse events (78% of studies), survival (54%), symptom control (39%) and mortality (31%). Key individual symptoms assessed were vomiting (41% of studies), nausea (34%) and pain (33%); 19% of studies assessed quality of life. Conclusions: Assessment focuses on survival, complications and overall symptom control. There is a need for definitions of treatment ‘success’ that are meaningful to patients, a more consistent approach to symptom assessment, and greater consideration of how to measure wellbeing in this population

Development of a Core Outcome Set for the research and assessment of inoperable malignant bowel obstruction

BackgroundMalignant bowel obstruction is experienced by 15% of people with advanced cancer, preventing them from eating and drinking and causing pain, nausea and vomiting. Surgery is not always appropriate. Management options include tube or stent drainage of intestinal contents and symptom control using medication. Published literature describing palliative interventions uses a broad range of outcome measures, few of which are patient-relevant. This hinders evidence synthesis, and fails to consider the perspectives of people undergoing treatment.AimsTo develop a Core Outcome Set for the assessment of inoperable malignant bowel obstruction with clinician, patient and caregiver involvement, using COMET methodology (Core Outcome Measures in Effectiveness Trials).MethodsA systematic review of clinical trials and observational studies, a rapid review of the qualitative literature and in-depth patient and clinician interviews were conducted to identify a comprehensive list of outcomes. Outcomes were compared and consolidated by the study Steering Group and Patient and Public Involvement contributors, and presented to an international clinical Expert Panel for review. Outcomes from the finalised list were rated for importance in a three-round international Delphi process: results of two survey rounds were circulated to respondents, and two separate consensus meetings were conducted with clinicians and with patients and caregivers via virtual conferencing, using live polling to reach agreement on a Core Outcome Set.Results130 unique outcomes were identified. Following the independent Expert Panel review, 82 outcomes were taken into round 1 of the Delphi survey; 24 outcomes reached criteria for critical importance across all stakeholder groups and none reached criteria for dropping. All outcomes rated critically important were taken forward for re-rating in round 2 and all other outcomes dropped. In round 2, all outcomes were voted critically important by at least one stakeholder group. Round 2 outcomes were presented again at online consensus meetings, categorised as high ranking (n = 9), middle ranking (n = 7) or low ranking (n = 8). Stakeholders reached agreement on 16 core outcomes across four key domains: Symptom control, Life impact, Treatment outcomes, and Communication and patient preferences.ConclusionUse of this Core Outcome Set can help to address current challenges in making sense of the evidence around treatment for inoperable malignant bowel obstruction to date, and underpin a more robust future approach. Clearer communication and an honest understanding between all stakeholders will help to provide a basis for responsible decision-making in this distressing situation in clinical practice

#35 - Enamel isotopes reveal late Pleistocene ecosystem dynamics in southeastern North America

The end of the late Pleistocene (~10,000 years ago) witnessed the extinction of over seventy percent of North America’s megafaunal genera. Although this pattern has been extensively investigated, its causal mechanisms remain elusive. Much of this difficulty is related to the spatial and temporal discontinuity of sites dating to the period leading up to the extinctions. Due to its removal from glacial conditions, southeastern North America provides a unique window into ecosystem dynamics just prior to human arrival in the region. In this study, we present new stable carbon and oxygen isotope data from Mammuthus columbiand Bison latifronsteeth collected from a well-dated Last Glacial Maximum (~20,000 rcybp) locality called Clark Quarry in coastal Georgia, USA. We compare these data to those from similarly aged (middle and late Rancholabrean) localities from Florida and demonstrate the presence of a vegetation gradient with elevated levels of C3vegetation at higher latitudes. We hypothesize that this pattern may have contributed to previously described migratory patterns of mastodon (Mammut) populations in southeastern North America. Serially-sampled δ13C and δ18O values suggest that Clark Quarry Mammuthus and Bison changed their diet seasonally with the incorporation of elevated quantities of C4vegetation during warmer periods. Our data indicate more exaggerated seasonal dietary variability in these taxa at Clark Quarry relative to those collected from the interglacial locality of Waccasassa River in Florida, providing additional evidence for the significant influence of glacial dynamics in structuring North American ecosystems