Diversity-dependent speciation and extinction in hominins.

The search for drivers of hominin speciation and extinction has tended to focus on the impact of climate change. Far less attention has been paid to the role of interspecific competition. However, research across vertebrates more broadly has shown that both processes are often correlated with species diversity, suggesting an important role for interspecific competition. Here we ask whether hominin speciation and extinction conform to the expected patterns of negative and positive diversity dependence, respectively. We estimate speciation and extinction rates from fossil occurrence data with preservation variability priors in a validated Bayesian framework and test whether these rates are correlated with species diversity. We supplement these analyses with calculations of speciation rate across a phylogeny, again testing whether these are correlated with diversity. Our results are consistent with clade-wide diversity limits that governed speciation in hominins overall but that were not quite reached by the Australopithecus and Paranthropus subclade before its extinction. Extinction was not correlated with species diversity within the Australopithecus and Paranthropus subclade or within hominins overall; this is concordant with climate playing a greater part in hominin extinction than speciation. By contrast, Homo is characterized by positively diversity-dependent speciation and negatively diversity-dependent extinction-both exceedingly rare patterns across all forms of life. The genus Homo expands the set of reported associations between diversity and macroevolution in vertebrates, underscoring that the relationship between diversity and macroevolution is complex. These results indicate an important, previously underappreciated and comparatively unusual role of biotic interactions in Homo macroevolution, and speciation in particular. The unusual and unexpected patterns of diversity dependence in Homo speciation and extinction may be a consequence of repeated Homo range expansions driven by interspecific competition and made possible by recurrent innovations in ecological strategies. Exploring how hominin macroevolution fits into the general vertebrate macroevolutionary landscape has the potential to offer new perspectives on longstanding questions in vertebrate evolution and shed new light on evolutionary processes within our own lineage.

Ghosts of extinct apes: genomic insights into African hominid evolution.

We are accustomed to regular announcements of new hominin fossils. There are now some 6000 hominin fossils, and up to 31 species. However, where are the announcements of African ape fossils? The answer is that there are almost none. Our knowledge of African ape evolution is based entirely on genomic analyses, which show that extant diversity is very young. This contrasts with the extensive and deep diversity of hominins known from fossils. Does this difference point to low and late diversification of ape lineages, or high rates of extinction? The comparative evolutionary dynamics of African hominids are central to interpreting living ape adaptations, as well as understanding the patterns of hominin evolution and the nature of the last common ancestor.

Resilience and burnout of healthcare workers during the early COVID-19 pandemic.

INTRODUCTION: The COVID-19 pandemic has led to significantly more healthcare workers (HCWs) experiencing burnout than previously. This burnout is strongly associated with low resilience. Addressing organisational stresses and the introduction of resilience training will help to reduce the proportion of HCWs experiencing this phenomenon. AIMS: The aim of this study was to assess the impact of the biopsychosocial changes and challenges associated with the COVID-19 pandemic on the healthcare workforce, exploring, specifically, the impact on and relationship between HCWs' resilience and burnout. METHODS: An electronic opt-in survey was distributed to HCWs through hospital and professional association communications emails and websites, as well as social media. The survey consisted of demographic questions, the Oldenburg Burnout Inventory to assess burnout, Brief Resilience Scale to assess general resilience, and 10-item Connor-Davidson Resilience Scale to assess resilience during the pandemic. Univariate and multivariate analysis was undertaken to examine the relationship between these factors. RESULTS: A total of 1370 HCWs completed the questionnaire, with 802 (58.5%) having burnout, 348 (25.4%) having low general resilience and 390 (28.5%) having low COVID resilience. Burnout was significantly associated with being public sector workers, low general resilience and low COVID resilience. Resilience training was found to be protective for burnout. CONCLUSION: The introduction of resilience training in the workplace is a fundamental tool that will significantly benefit HCWs when working under challenging conditions.

The Distribution and Biogenic Origins of Zinc in the Mineralised Tooth Tissues of Modern and Fossil Hominoids: Implications for Life History, Diet and Taphonomy.

Zinc is incorporated into enamel, dentine and cementum during tooth growth. This work aimed to distinguish between the processes underlying Zn incorporation and Zn distribution. These include different mineralisation processes, the physiological events around birth, Zn ingestion with diet, exposure to the oral environment during life and diagenetic changes to fossil teeth post-mortem. Synchrotron X-ray Fluorescence (SXRF) was used to map zinc distribution across longitudinal polished ground sections of both deciduous and permanent modern human, great ape and fossil hominoid teeth. Higher resolution fluorescence intensity maps were used to image Zn in surface enamel, secondary dentine and cementum, and at the neonatal line (NNL) and enamel-dentine-junction (EDJ) in deciduous teeth. Secondary dentine was consistently Zn-rich, but the highest concentrations of Zn (range 197-1743 ppm) were found in cuspal, mid-lateral and cervical surface enamel and were similar in unerupted teeth never exposed to the oral environment. Zinc was identified at the NNL and EDJ in both modern and fossil deciduous teeth. In fossil specimens, diagenetic changes were identified in various trace element distributions but only demineralisation appeared to markedly alter Zn distribution. Zinc appears to be tenacious and stable in fossil tooth tissues, especially in enamel, over millions of years.

Bilateral lunotriquetral coalition: a dynamic four-dimensional computed tomography technical case report.

Lunotriquetral coalitions are the most common form of carpal coalition wherein the cartilage between the lunate and triquetrum ossification centers failed to undergo apoptosis. This technical case report examines the arthrokinematics of bilateral lunotriquetral coalitions with dissimilar Minnaar types in one participant with one asymptomatic wrist and one wrist with suspected distal radioulnar joint injury. Static and dynamic (four-dimensional) CT images during pronosupination were captured using a photon-counting detector CT scanner. Interosseous proximity distributions were calculated between the lunotriquetral coalition and adjacent bones in both wrists to quantify arthrokinematics. Interosseous proximity distributions at joints adjacent to the lunotriquetral coalition demonstrate differences in median and minimum interosseous proximities between the asymptomatic and injured wrists during resisted pronosupination. Altered kinematics from lunotriquetral coalitions may be a source of ulnar-sided wrist pain and discomfort, limiting the functional range of motion. This case report highlights potential alterations to wrist arthrokinematics in the setting of lunotriquetral coalitions and possible associations with ulnar-sided wrist pain, highlighting anatomy to examine in radiographic follow-up. Furthermore, this case report demonstrates the technical feasibility of four-dimensional CT using photon-counting detector technology in assessing arthrokinematics in the setting of variant wrist anatomy.

Shibboleth: An agent-based model of signalling mimicry.

Mimicry is an essential strategy for exploiting competitors in competitive co-evolutionary relationships. Protection against mimicry may, furthermore, be a driving force in human linguistic diversity: the potential harm caused by failing to detect mimicked group-identity signals may select for high sensitivity to mimicry of honest group members. Here we describe the results of five agent-based models that simulate multi-generational interactions between two groups of individuals: original members of a group with an honest identity signal, and members of an outsider group who mimic that signal, aiming to pass as members of the in-group. The models correspond to the Biblical story of Shibboleth, where a tribe in conflict with another determines tribe affiliation by asking individuals to pronounce the word, 'Shibboleth.' In the story, failure to reproduce the word phonetically resulted in death. Here, we run five different versions of a 'Shibboleth' model: a first, simple version, which evaluates whether a composite variable of mimicry quality and detection quality is a superior predictor to the model's outcome than is cost of detection. The models thereafter evaluate variations on the simple model, incorporating group-level behaviours such as altruistic punishment. Our results suggest that group members' sensitivity to mimicry of the Shibboleth-signal is a better predictor of whether any signal of group identity goes into fixation in the overall population than is the cost of mimicry detection. Thus, the likelihood of being detected as a mimic may be more important than the costs imposed on mimics who are detected. This suggests that theoretical models in biology should place greater emphasis on the likelihood of detection, which does not explicitly entail costs, rather than on the costs to individuals who are detected. From a language learning perspective, the results suggest that admission to group membership through linguistic signals is powered by the ability to imitate and evade detection as an outsider by existing group members.

The Effect of Oral Laxatives on Rectal Distension and Image Quality in Magnetic Resonance Imaging of the Prostate.

Introduction Increasing rectal size is associated with increased artefacts on magnetic resonance imaging (MRI) of the prostate and has the potential to degrade image quality. The objective of this study was to analyse the effect of oral laxative medication on rectal distension and image quality in prostate MRI. Methods Eighty patients prospectively received either 15 mg of oral senna (laxative group) or no medication (control group). Patients underwent prostate MRI according to standard local protocol and seven rectal dimensions on axial and sagittal images were measured. A subjective assessment of rectal distension was also made using a five-point Likert scale. Finally, artefacts on diffusion-weighted sequences were assessed using a four-point Likert scale. Results There was a small reduction in rectal diameter on sagittal images in the laxative group compared to the control group, with mean diameters of 27.1 mm and 30.0 mm respectively, p=0.02. There was no significant difference in rectal measurements of anteroposterior diameter, transverse diameter, or rectal circumference on axial imaging. Subjective scoring also demonstrated no significant difference in diffusion-weighted imaging quality between the laxative group and control group, p=0.82. Conclusion Bowel preparation with the oral laxative, senna, provided only a marginal decrease in rectal distension on one measure and no reduction in artefacts on diffusion-weighted sequences. The findings of this study do not support the routine use of this medication in patients undergoing prostate MRI.

Patterns of variation in canal and root number in human post-canine teeth.

Descriptive morphology of tooth roots traditionally focuses on number of canals and roots. However, how or if canal and root number are related is poorly understood. While it is often assumed that canal number is concomitant with root number and morphology, in practice canal number and morphology do not always covary with external root features. To investigate the relationship between canal and root number, fully developed, adult post-canine teeth were examined and quantified from computerized tomography scans from a global sample of 945 modern humans. We tested the hypotheses that root and canal number do not follow a 1:1 ratio, that canal to root ratios differ between teeth, and that canal to root ratios differ across major human geographical groups. Results indicate that not only is root number dependent on canal number, but that this relationship becomes more variable as canal number increases, varies between individual teeth and by major geographical group, and changes as these groups increase in geographical distance from Sub-Saharan Africa. These results show that the ratio of canal number to root number is an important indicator of variation in dental phenotypes.

Models of gene-culture evolution are incomplete without incorporating epigenetic effects.

Epigenetics impacts gene-culture coevolution by amplifying phenotypic variation, including clustering, and bridging the difference in timescales between genetic and cultural evolution. The dual inheritance model described by Uchiyama et al. could be modified to provide greater explanatory power by incorporating epigenetic effects.

A process-based approach to hominin taxonomy provides new perspectives on hominin speciation.

A longstanding debate in hominin taxonomy is that between "lumpers" and "splitters." We argue that both approaches assume an unrealistically static model of speciation. Speciation is an extended process, of which fossils provide a record. Fossils should be interpreted in a more dynamic framework than is the norm. We introduce the process-based approach (PBA), in which we suggest that "splitters" recognize and name units at an earlier stage of speciation than "lumpers" do. The "determinants" of speciation can control the rate at which population isolates form, or the rate at which these complete the speciation process, or both. Embedded in the PBA, differences between existing lumped and split taxonomies are a heuristic tool to study these processes. We apply the PBA to show that not all hominin populations reached later stages of the speciation process and that populations have a disproportionate likelihood of doing so from ∼3.1 to ∼1.5 Ma. We outline and discuss resulting new research questions.

Does experience matter? The relationship between nephrologist characteristics and end stage kidney disease patient outcomes.

BACKGROUND: Nephrology offers the unique opportunity to directly link patients to providers, allowing the study of patient outcomes at the provider level. The purpose of this analysis was to determine whether nephrologist experience, defined as years in nephrology practice, was associated with clinical outcomes. DESIGN: Physician data contained within the American Medical Association (AMA) Physician Masterfile was combined with patient and Medicare claims data from the United States Renal Data System (USRDS) for the calendar year 2012, with follow up extending through June 30, 2014. Associations with important healthcare outcomes including mortality in patients receiving maintenance renal replacement therapy (RRT), waitlisting for kidney transplantation, and receipt of a kidney transplant were determined with broad adjustment for both patient and provider level variables, with attention on tertile of provider time in practice. RESULTS: We identified 256,324 patients on maintenance RRT cared for by 6193 nephrologists. Nephrologists with the least experience were more likely to be female, reside in a region with ≥1,000,000 people, have a Doctor of Osteopathic Medicine degree, and have a listed maintenance of certification status as "yes." Overall, 30.2% of the cohort died at a mean follow up of 1.99 years. Compared to those with the 0-10 years of experience, receipt of care from nephrologists with more experience was associated with lower mortality (AHR 0.97 CI 0.94-0.99 for nephrologists with 11-20 years) and increased listing for kidney transplantation (AHR 1.10; CI 1.01-1.21 for nephrologists with >21 years experience). Experience level did not result in a difference in kidney transplantation rates. CONCLUSIONS: Receipt of maintenance RRT from nephrologists with greater experience was associated with decreased mortality and increased listing for kidney transplantation, an effect that remained significant after multiple adjustments for important patient and nephrologist variables.

Renal cell carcinoma presenting as painless jaundice and unintentional weight loss.

Painless jaundice and unexplained weight loss is an exceedingly rare presentation for renal cell carcinoma (RCC). Such a presentation is more typical of a hepatocellular pathology. Stauffer syndrome is a paraneoplastic syndrome seen in RCC and is characterized by deranged hepatic enzymes and in association with fever, fatigue and weight loss. These symptoms typically resolve following nephrectomy. The predominant picture of this syndrome is that of an anicteric patient. Here we report the case of a 48 year old man who presented with a 3 week history of painless jaundice, malaise, anorexia and unintentional weight loss of 10 kilograms. Imaging revealed a solid right renal mass measuring 11 cm × 11 cm × 14 cm. There were also findings consistent with the presence of an inferior vena cava thrombosis and multiple pulmonary lesions. Biopsy confirmed the pulmonary lesions as metastatic clear cell renal carcinoma. Following multi-disciplinary discussion, cytoreductive nephrectomy was recommended to the patient, however multiple paraneoplastic syndromes subsequently developed and the patient experienced hypertension, severe coagulopathy and hypercalcaemia. Subsequently, the patient opted for supportive and palliative care. The patient died 2 weeks after initial presentation. Paraneoplastic syndromes associated with RCC are often underdiagnosed due to their variety and often non-specific nature. Paraneoplastic syndromes may lead to patient presentation, where they often suggest advanced or metastatic disease, and those caring for such patients should remain vigilant as further syndromes may complicate patient care.

A novel system for classifying tooth root phenotypes.

Human root and canal number and morphology are highly variable, and internal root canal form and count does not necessarily co-vary directly with external morphology. While several typologies and classifications have been developed to address individual components of teeth, there is a need for a comprehensive system, that captures internal and external root features across all teeth. Using CT scans, the external and internal root morphologies of a global sample of humans are analysed (n = 945). From this analysis a method of classification that captures external and internal root morphology in a way that is intuitive, reproducible, and defines the human phenotypic set is developed. Results provide a robust definition of modern human tooth root phenotypic diversity. The method is modular in nature, allowing for incorporation of past and future classification systems. Additionally, it provides a basis for analysing hominin root morphology in evolutionary, ecological, genetic, and developmental contexts.

Failure mode and effect analysis for linear accelerator-based paraspinal stereotactic body radiotherapy.

INTRODUCTION: Paraspinal stereotactic body radiotherapy (SBRT) involves risks of severe complications. We evaluated the safety of the paraspinal SBRT program in a large academic hospital by applying failure modes and effects analysis. METHODS: The analysis was conducted by a multidisciplinary committee (two therapists, one dosimetrist, four physicists, and two radiation oncologists). The paraspinal SBRT workflow was segmented into four phases (simulation, treatment planning, delivery, and machine quality assurance (QA)). Each phase was further divided into a sequence of sub-processes. Potential failure modes (PFM) were identified from each subprocess and scored in terms of the frequency of occurrence, severity and detectability, and a risk priority number (RPN). High-risk PFMs were identified based on RPN and were studied for root causes using fault tree analysis. RESULTS: Our paraspinal SBRT process was characterized by eight simulations, 11 treatment planning, nine delivery, and two machine QA sub-processes. There were 18, 29, 19, and eight PFMs identified from simulation, planning, treatment, and machine QA, respectively. The median RPN of the PFMs was 62.9 for simulation, 68.3 for planning, 52.9 for delivery, and 22.0 for machine QA. The three PFMs with the highest RPN were: previous radiotherapy outside the institution is not accurately evaluated (RPN: 293.3), incorrect registration between diagnostic magnetic resonance imaging and simulation computed tomography causing incorrect contours (273.0), and undetected patient movement before ExacTrac baseline (217.8). Remedies to the high RPN failures were implemented, including staff education, standardized magnetic resonance imaging acquisition parameters, and an image fusion process, and additional QA on beam steering. CONCLUSIONS: A paraspinal SBRT workflow in a large clinic was evaluated using a multidisciplinary and systematic risk analysis, which led to feasible solutions to key root causes. Treatment planning was a major source of PFMs that systematically affect the safety and quality of treatments. Accurate evaluation of external treatment records remains a challenge.

The discovery of an in situ Neanderthal remain in the Bawa Yawan Rockshelter, West-Central Zagros Mountains, Kermanshah.

Neanderthal extinction has been a matter of debate for many years. New discoveries, better chronologies and genomic evidence have done much to clarify some of the issues. This evidence suggests that Neanderthals became extinct around 40,000-37,000 years before present (BP), after a period of coexistence with Homo sapiens of several millennia, involving biological and cultural interactions between the two groups. However, the bulk of this evidence relates to Western Eurasia, and recent work in Central Asia and Siberia has shown that there is considerable local variation. Southwestern Asia, despite having a number of significant Neanderthal remains, has not played a major part in the debate over extinction. Here we report a Neanderthal deciduous canine from the site of Bawa Yawan in the West-Central Zagros Mountains of Iran. The tooth is associated with Zagros Mousterian lithics, and its context is preliminary dated to between ~43,600 and ~41,500 years ago.

Randomized Controlled Trials 2: Analysis.

When analyzing the results of a trial, the primary outcome variable must be kept in clear focus. In the analysis plan, consideration must be given to comparing the characteristics of the subjects, taking account of differences in these characteristics, intention-to-treat analysis, interim analyses and stopping rules, mortality comparisons, composite outcomes, research design including run-in periods, factorial, stratified and crossover designs, number needed to treat, power issues, multivariate modeling, subgroup analysis, competing risks, and hypothesis-generating analyses.

Randomized Controlled Trials 4: Planning, Analysis, and Interpretation of Quality-of-Life Studies.

Quality-of-life (QoL) outcomes are important elements of randomized controlled trials. The instruments for measurement of QoL vary but usually multiple comparisons are possible, a concern that can be offset by prespecifying the outcomes of interest. Missing data may threaten the validity of QoL assessments in trials. Therefore, familiarity with the strategies used to account for missing data is necessary. Measures that incorporate both survival and QoL are helpful for treatment decisions. The definition of minimal clinically important differences in QoL scores is important and often derived using inadequate methods.

Interobserver Agreement in the Diagnosis of Parkinson Disease with Cardiac 123I-Metaiodobenzylguanidine Scintigraphy.

The aim of this study was to analyze the interobserver agreement of visual and quantitative assessment of cardiac 123I-metaiodobenzylguanidine scintigraphy. Methods: Planar images were acquired using a low-energy collimator. The heart-to-mediastinum (HM) ratio was adjusted for the use of a low-energy collimator, using a published formula. Interpretation was undertaken both visually and after the addition of adjusted HM ratios. Image findings were classified as normal, abnormal, or borderline. Results: The cohort consisted of 10 patients. On visual interpretation only, there was strong agreement on the interpretation of the scan (κ = 0.82, P < 0.01). Adjusted HM ratios led to a significant increase in mean ratios (1.79 vs. 1.36, P = 0.02) and, when utilized in reporting, resulted in perfect agreement (κ = 1.0, P < 0.01). Conclusion: The use of quantified HM ratios adjusted for low-energy collimator use improves on visual assessment alone and allowed for excellent interobserver agreement.