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Elementary treatments of Markov chains, especially those devoted to discrete-time and finite state-space theory, leave the impression that everything is smooth and easy to understand. This exposition of the works of Kolmogorov, Feller, Chung, Kato and other mathematical luminaries focuses on time-continuous chains but is not so far from being elementary itself. It reminds us once again that the first impression is false: an infinite, but denumerable state-space is where the fun begins. If you have not heard of Blackwell's example (in which all states are instantaneous), do not understand what the minimal process is, or do not know what happens after explosion, dive right in. But beware lest you are enchanted: 'There are more spells than your commonplace magicians ever dreamed of.'
We elaborate a general workflow of weighting-based survey inference, decomposing it into two main tasks. The first is the estimation of population targets from one or more sources of auxiliary information. The second is the construction of weights that calibrate the survey sample to the population targets. We emphasize that these tasks are predicated on models of the measurement, sampling, and nonresponse process whose assumptions cannot be fully tested. After describing this workflow in abstract terms, we then describe in detail how it can be applied to the analysis of historical and contemporary opinion polls. We also discuss extensions of the basic workflow, particularly inference for causal quantities and multilevel regression and poststratification.
One of the fundamental roles of human imagination is to enable the representation of possible future events. Here, we survey some of the most critical abilities that this foresight supports: anticipating future emotions, setting and pursuing goals, preparing for threats, deliberately acquiring skills and knowledge, and intentionally shaping the future environment. Furthermore, we outline how metacognition bolsters human capacities even further by enabling people to reflect on and compensate for the natural limits of their foresight. For example, humans make contingency plans because they appreciate that their initial predictions may turn out to be wrong. We suggest that the processes involved in monitoring, controlling, and ultimately augmenting future-oriented imagination represent an important and understudied parallel of “metamemory” that should be called “metaforesight.”
Writing in the 1880s, Galton recognized that some healthy individuals lack visual imagery. This phenomenon has been relatively neglected since then. In 2015 we coined the term “aphantasia” to describe the lack of the mind’s eye, reporting on twenty-one individuals with a lifelong lack of imagery. Since then we have been contacted by many thousands of people lying at both the aphantasic and the hyperphantasic extremes of the vividness spectrum. Preliminary evidence suggests that lifelong aphantasia is associated variably with prosopagnosia and reduction in autobiographical memory; hyperphantasia is associated with synaesthesia. Over 50 percent of people with aphantasia report visual dreaming. In around 50 percent of our aphantasic participants, all modalities of imagery are affected, while in others some modalities of imagery are preserved. Aphantasia often runs in families. Functional imaging studies of imagery suggest a range of hypotheses for the neural correlates of aphantasia; the few functional imaging studies specifically examining imagery vividness point to positive correlations with brain activity in higher visual and memory-related areas. The study of aphantasia reminds us how easily invisible differences can escape detection. Visualization is only one of many ways of representing things in their absence, and individuals lacking visual imagery can be highly imaginative.
College is a key pathway to political participation, and lower-income individuals especially stand to benefit from it given their lower political participation. However, rising inequality makes college disproportionately more accessible to high-income students. One consequence of inequality is a prevalence of predominantly affluent campuses. Colleges are thus not insulated from the growing concentration of affluence in American social spaces. We ask how affluent campus spaces affect college’s ability to equalize political participation. Predominantly affluent campuses may create participatory norms that especially elevate low-income students’ participation. Alternatively, they may create affluence-centered social norms that marginalize these students, depressing their participation. A third possibility is equal effects, leaving the initial gap unchanged. Using a large panel survey (201,011 students), controls on many characteristics, and tests for selection bias, we find that predominantly affluent campuses increase political participation to a similar extent for all income groups, thus leaving the gap unchanged. We test psychological, academic, social, political, financial, and institutional mechanisms for the effects. The results carry implications for the self-reinforcing link between inequality and civic institutions.
Analysis of food webs is important for defining functional components of ecosystems, but dietary data are often difficult to obtain and coarsely characterised. We compared three methods of rainbow trout (Oncorhynchus mykiss (Walbaum); Salmoniformes: Salmonidae) and prickly sculpin (Cottus asper Richardson; Scorpaeniformes: Cottidae) gut content analysis: traditional morphological taxonomy of prey items, genetic sequencing of individual prey items, and next-generation sequencing of homogenised gut contents. Prey analysis of invertebrates by morphological identification allowed order-level classifications and produced ecologically important count and mass data. Sequencing individual specimens provided greater taxonomic resolution, while next-generation sequencing of stomach contents revealed more prey diversity in the diets of both fish species as it was possible to detect prey that were degraded beyond visual recognition. Both fish species exhibited generalist feeding characteristics; however, terrestrial Insecta were a large diet component for rainbow trout. This study demonstrates an efficient approach for prey analysis using molecular techniques that complement traditional taxonomy.
The current Covid-19 pandemic is not just a medical and social tragedy, but within the threat of the outbreak looms the potential for a significant and persistent negative mental health impact, based on previous experience with other pandemics such as SARS in 2003 and the earlier H1N1 outbreak of 1918. This piece will highlight the links between depression and viral illnesses and explore important overlaps with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome, potentially implicating inflammatory mechanisms in those exposed to a range of viral agents. While containment of psychological distress currently focuses on social anxiety and quarantine measures, a second wave of psychological morbidity due to viral illness may be imminent.
Empirical work on motivated reasoning suggests that our judgments are influenced to a surprising extent by our wants, desires, and preferences (Kahan 2016; Lord, Ross, and Lepper 1979; Molden and Higgins 2012; Taber and Lodge 2006). How should we evaluate the epistemic status of beliefs formed through motivated reasoning? For example, are such beliefs epistemically justified? Are they candidates for knowledge? In liberal democracies, these questions are increasingly controversial as well as politically timely (Beebe et al. 2018; Lynch Forthcoming, 2018; Slothuus and de Vreese 2010). And yet, the epistemological significance of motivated reasoning has been almost entirely ignored by those working in mainstream epistemology. We aim to rectify this oversight. Using politically motivated reasoning as a case study, we show how motivated reasoning gives rise to three distinct kinds of skeptical challenges. We conclude by showing how the skeptical import of motivated reasoning has some important ramifications for how we should think about the demands of intellectual humility.
When contentious blasphemy laws are pressed into service in fledgling democracies with illiberal tendencies such as Indonesia, critical questions arise about judicial integrity and the political nature of blasphemy trials. Judicial legitimacy in Indonesia is defined according to international standards and conventions. The focus is on judicial propriety rather than the popularity or majoritarian appeal of court decisions. In May 2017 a watershed moment occurred in Indonesia as the former governor of Jakarta Basuki Tjahaja Purnama (popularly known as Ahok) was found guilty of desecrating religion and sentenced to 2 years in prison. Judgments rendered in politicized blasphemy trials such as these fail to meet standards of impartiality, and when discursive transgressions of a blasphemous nature occur there are deep ambiguities of meaning and intent. This paper contends that the revival of blasphemy as a punishable crime relates to political power calculations and electoral opportunities, and offers an analysis of blasphemy in Indonesia through the quasi-historical lens of a discursive crime premised on the fallacy that religious offence threatens public order. Blasphemy trials are further complicated by the fact that religious authorities and Islamic mass organizations in Indonesia have significant influence over judicial processes.
It is traditionally taught that the location to place an ultrasound probe to detect a pneumothorax with point-of-care ultrasound (POCUS) is the anterior chest, given the theory that air will collect at the least dependent area in the supine patient. There is a wide variety of scanning protocols with varying accuracy and completeness. We sought to assess the optimal area to scan for diagnosing pneumothorax by mapping the location of traumatic pneumothorax on computed tomography (CT).
Patients were selected after a retrospective cohort of adult patients who presented to a regional trauma center with a pneumothorax diagnosed on CT. Data were extracted using a standardized data collection tool, and 20% of charts were reviewed by two reviewers. Predefined zones were used to map the areas of pneumothoraces. Theoretical sensitivity and 95% confidence intervals (CIs) are reported.
A total of 203 traumatic pneumothoraces were reviewed from 2006 to 2016. The majority of the pneumothoraces were found in an area defined by the para-sternal border and the mid-clavicular line from the inferior aspect of the clavicle to the physiologic lung point (liver on the right, heart on the left). The theoretical sensitivity for pneumothorax of scanning this area was 91.6% (95% CI, 86.9–95%).
This study suggests any POCUS scanning protocol for traumatic pneumothorax should include an area from the inferior border of the clavicle at the parasternal border down to the liver or cardiac lung points and then the mid clavicular line down to the liver or cardiac lung points.
Personal protective equipment (PPE) is worn by prehospital providers (PHPs) for protection from hazardous exposures. Evidence regarding the ability of PHPs to perform resuscitation procedures has been described in adult but not pediatric models. This study examined the effects of PPE on the ability of PHPs to perform resuscitation procedures on pediatric patients.
This prospective study was conducted at a U.S. simulation center. Paramedics wore normal attire at the baseline session and donned full Level B PPE for the second session. During each session, they performed timed sets of psychomotor tasks simulating clinical care of a critically ill pediatric patient. The difference in time to completion between baseline and PPE sessions per task was examined using Wilcoxon signed-rank tests.
A total of 50 paramedics completed both sessions. Median times for task completion at the PPE sessions increased significantly from baseline for several procedures: tracheal intubation (+4.5 seconds, P=0.01), automated external defibrillator (AED) placement (+9.5 seconds, P=0.01), intraosseous line insertion (+7 seconds, P<.0001), tourniquet (+8.5 seconds, P<.0001), intramuscular injection (+21–23 seconds, P<.0001), and pulse oximetry (+4 seconds, P<.0001). There was no significant increase in completion time for bag-mask ventilation or autoinjector use.
PPE did not have a significant impact on PHPs performing critical tasks while caring for a pediatric patient with a highly infectious or chemical exposure. This information may guide PHPs faced with the situation of resuscitating children while wearing Level B PPE.
This pilot study explored personal disaster preparedness of nursing staff and their ability and willingness to respond following a disaster.
All nurses from a single hospital were invited to participate; 91 completed an online survey asking them to rate their ability and willingness to report to work following the disaster scenarios and to indicate whether they had pursued various preparedness activities. Data were analyzed by descriptive and inferential statistics using Minitab 17 Statistical Software.
Participants reflected a cross-section of major acute care units and nursing specialties. The majority of participants indicated being able and willing to report to work following the disaster scenarios. Personal disaster preparedness varied, with few activities pursued by the majority. Few scenarios produced a relationship between preparedness activities and ability or willingness to report to work.
Despite the majority of participants indicating they would be able and willing to report to work during a disaster, they acknowledged barriers affecting them. Most disaster scenarios showed no statistically significant relationship with preparedness activities. Nurses should consider barriers that affect their own availability for work following a disaster and identify potential solutions. Future research related to mitigation of possible barriers to surge capacity would be useful.
The cognitions and emotions of people prone to hoarding are key components of the dominant cognitive behavioural model of hoarding disorder.
This study sought to use Q-methodology to explore the thoughts and feelings of people that are prone to hoarding, to identify whether distinct clusters of participants could be found.
A 49-statement Q-set was generated following thematic analysis of initial interviews (n = 2) and a review of relevant measures and literature. Forty-one participants with problematic hoarding met various study inclusion criteria and completed the Q-sort (either online or offline). A by-person factor analysis was conducted and subsequent participant clusters compared on psychometric measures of mood, anxiety, hoarding and time taken on the online task as proxy for impulsivity.
Four distinct participant clusters were found constituting 34/41 (82.92%) of the participants, as the Q-sorts of n = 7 participants failed to cluster. The four clusters found were ‘overwhelmed’ (n = 11 participants); ‘aware of consequences’ (n = 13 participants); ‘object complexity’ (n = 6 participants) and ‘object–affect fusion’ (n = 4 participants). The clusters did not markedly differ with regard to hoarding severity, anxiety, depression or impulsivity.
Whilst the participant clusters reflect extant research evidence, they also reveal significant heterogeneity and so prompt the need for further research investigating emotional and cognitive differences between people prone to hoarding.
Intracranial pressure (ICP) is well recognised as a critical parameter to both measure and influence in the management of the head injured patient. Since Lundberg’s seminal studies, ICP has arguably become the major focus of monitoring in head injury, as well as a number of other neurosurgical scenarios.1 Mean ICP and the features that make up the ICP waveform provide insight into the state of elastance and compliance of the injured brain, impending trends and events related to changes in intracranial pathophysiology, and also end-prognosis in traumatic brain injury (TBI).