To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Using numerical simulations, we probe the fluid flow in an axisymmetric peristaltic vessel fitted with elastic bi-leaflet valves. In this biomimetic system that mimics the flow generated in lymphatic vessels, we investigate the effects of the valve and vessel properties on pumping performance of the valved peristaltic vessel. The results indicate that valves significantly increase pumping by reducing backflow. The presence of valves, however, increases the viscous resistance, therefore requiring greater work compared to valveless vessels. The benefit of the valves is the most significant when the fluid is pumped against an adverse pressure gradient and for low vessel contraction wave speeds. We identify the optimum vessel and valve parameters leading to the maximum pumping efficiency. We show that the optimum valve elasticity maximizes the pumping flow rate by allowing the valve to block the backflow more effectively while maintaining low resistance during the forward flow. We also examine the pumping in vessels where the vessel contraction amplitude is a function of the adverse pressure gradient, as found in lymphatic vessels. We find that, in this case, the flow is limited by the work generated by the contracting vessel, suggesting that the pumping in lymphatic vessels is constrained by the performance of the lymphatic muscle. Given the regional heterogeneity of valve morphology observed throughout the lymphatic vasculature, these results provide insight into how these variations might facilitate efficient lymphatic transport in the vessel's local physiologic context.
The relationship between wisdom and fluid intelligence (Gf) is poorly understood, particularly in older adults. We empirically tested the magnitude of the correlation between wisdom and Gf to help determine the extent of overlap between these two constructs.
Cross-sectional study with preregistered hypotheses and well-powered analytic plan (https://osf.io/h3pjx).
Memory and Aging Center at the University of California San Francisco, located in the USA.
Wisdom was quantified using a well-validated self-report-based scale (San Diego Wisdom Scale or SD-WISE). Gf was assessed via composite measures of processing speed (Gf-PS) and executive functioning (Gf-EF). The relationships of SD-WISE scores to Gf-PS and Gf-EF were tested in bivariate correlational analyses and multiple regression models adjusted for demographics (age, sex, and education). Exploratory analyses evaluated the relationships between SD-WISE and age, episodic memory performance, and dorsolateral and ventromedial prefrontal cortical volumes on magnetic resonance imaging.
Wisdom showed a small, positive association with Gf-EF (r = 0.181 [95% CI 0.016, 0.336], p = .031), which was reduced to nonsignificance upon controlling for demographics, and no association with Gf-PS (r = 0.019 [95% CI −0.179, 0.216], p = .854). Wisdom demonstrated a small, negative correlation with age (r = −0.197 [95% CI −0.351, −0.033], p = .019), but was not significantly related to episodic memory or prefrontal volumes.
Our findings indicate that most of the variance in wisdom (>95%) is unaccounted for by Gf. The independence of wisdom from cognitive functions that reliably show age-associated declines suggests that it may hold unique potential to bolster decision-making, interpersonal functioning, and other everyday activities in older adults.
This study aimed to compare the necessary scutum defect for transmeatal visualisation of middle-ear landmarks between an endoscopic and microscopic approach.
Human cadaveric heads were used. In group 1, middle-ear landmarks were visualised by endoscope (group 1 endoscopic approach) and subsequently by microscope (group 1 microscopic approach following endoscopy). In group 2, landmarks were visualised solely microscopically (group 2 microscopic approach). The amount of resected bone was evaluated via computed tomography scans.
In the group 1 endoscopic approach, a median of 6.84 mm3 bone was resected. No statistically significant difference (Mann–Whitney U test, p = 0.163, U = 49.000) was found between the group 1 microscopic approach following endoscopy (median 17.84 mm3) and the group 2 microscopic approach (median 20.08 mm3), so these were combined. The difference between the group 1 endoscopic approach and the group 1 microscopic approach following endoscopy plus group 2 microscopic approach (median 18.16 mm3) was statistically significant (Mann–Whitney U test, p < 0.001, U = 18.000).
This study showed that endoscopic transmeatal visualisation of middle-ear landmarks preserves more of the bony scutum than a microscopic transmeatal approach.
Despite broad evidence suggesting that adversity-exposed youth experience an impaired ability to recognize emotion in others, the underlying biological mechanisms remains elusive. This study uses a multimethod approach to target the neurological substrates of this phenomenon in a well-phenotyped sample of youth meeting diagnostic criteria for posttraumatic stress disorder (PTSD). Twenty-one PTSD-afflicted youth and 23 typically developing (TD) controls completed clinical interview schedules, an emotion recognition task with eye-tracking, and an implicit emotion processing task during functional magnetic resonance imaging )fMRI). PTSD was associated with decreased accuracy in identification of angry, disgust, and neutral faces as compared to TD youth. Of note, these impairments occurred despite the normal deployment of visual attention in youth with PTSD relative to TD youth. Correlation with a related fMRI task revealed a group by accuracy interaction for amygdala–hippocampus functional connectivity (FC) for angry expressions, where TD youth showed a positive relationship between anger accuracy and amygdala–hippocampus FC; this relationship was reversed in youth with PTSD. These findings are a novel characterization of impaired threat recognition within a well-phenotyped population of severe pediatric PTSD. Further, the differential amygdala–hippocampus FC identified in youth with PTSD may imply aberrant efficiency of emotional contextualization circuits.
Lichens occupy diverse substrates across tremendous ranges of environmental variation. In boreal forests, lichen communities co-occur in ‘strata’ defined by terrestrial or arboreal substrates, but these strata may or may not be interchangeable as bioindicators. Do co-occurring lichen strata have similar community structures and environmental responses? Could one stratum serve as a proxy for the other? We assessed variation in species richness and community compositions between ground-layer versus epiphyte-layer lichen strata in boreal forests and peatlands of interior Alaska. Species richness was lower and more spatially structured in the ground layer than the epiphyte layer. Richness of strata was not correlated. The most compositionally unique ground-layer communities were species-poor but contained regionally rare species not common in other plots. Variation in community compositions (ordination scores) were not congruent between strata (Procrustes congruence < 0.16 on 0–1 scale); the largest departures from congruence occurred where ground layers were species-poor. The best predictors of ground-layer community compositions were hydrological and topographic, whereas epiphytes were most associated with macroclimate and tree abundances. We conclude that lichens on different substrates ‘move in different circles’: compositional gradients did not agree and the environmental gradients most important to each lichen stratum were not the same. The conditions which strongly influence one vegetation stratum may have little bearing upon another. As global changes modify habitats, an incremental change in environment may lead community trajectories to diverge among lichen strata.
Identifying predictors of patient outcomes evaluated over time may require modeling interactions among variables while addressing within-subject correlation. Generalized linear mixed models (GLMMs) and generalized estimating equations (GEEs) address within-subject correlation, but identifying interactions can be difficult if not hypothesized a priori. We evaluate the performance of several variable selection approaches for clustered binary outcomes to provide guidance for choosing between the methods.
We conducted simulations comparing stepwise selection, penalized GLMM, boosted GLMM, and boosted GEE for variable selection considering main effects and two-way interactions in data with repeatedly measured binary outcomes and evaluate a two-stage approach to reduce bias and error in parameter estimates. We compared these approaches in real data applications: hypothermia during surgery and treatment response in lupus nephritis.
Penalized and boosted approaches recovered correct predictors and interactions more frequently than stepwise selection. Penalized GLMM recovered correct predictors more often than boosting, but included many spurious predictors. Boosted GLMM yielded parsimonious models and identified correct predictors well at large sample and effect sizes, but required excessive computation time. Boosted GEE was computationally efficient and selected relatively parsimonious models, offering a compromise between computation and parsimony. The two-stage approach reduced the bias and error in regression parameters in all approaches.
Penalized and boosted approaches are effective for variable selection in data with clustered binary outcomes. The two-stage approach reduces bias and error and should be applied regardless of method. We provide guidance for choosing the most appropriate method in real applications.
Gravitational waves from coalescing neutron stars encode information about nuclear matter at extreme densities, inaccessible by laboratory experiments. The late inspiral is influenced by the presence of tides, which depend on the neutron star equation of state. Neutron star mergers are expected to often produce rapidly rotating remnant neutron stars that emit gravitational waves. These will provide clues to the extremely hot post-merger environment. This signature of nuclear matter in gravitational waves contains most information in the 2–4 kHz frequency band, which is outside of the most sensitive band of current detectors. We present the design concept and science case for a Neutron Star Extreme Matter Observatory (NEMO): a gravitational-wave interferometer optimised to study nuclear physics with merging neutron stars. The concept uses high-circulating laser power, quantum squeezing, and a detector topology specifically designed to achieve the high-frequency sensitivity necessary to probe nuclear matter using gravitational waves. Above 1 kHz, the proposed strain sensitivity is comparable to full third-generation detectors at a fraction of the cost. Such sensitivity changes expected event rates for detection of post-merger remnants from approximately one per few decades with two A+ detectors to a few per year and potentially allow for the first gravitational-wave observations of supernovae, isolated neutron stars, and other exotica.
Quasicrystalline alloys and their composites have been extensively studied due to their complex atomic structures, mechanical properties, and their unique tribological and thermal behaviors. However, technological applications of these materials have not yet come of age and still require additional developments. In this review, we discuss the recent advances that have been made in the last years toward optimizing fabrication processes and properties of Al-matrix composites reinforced with quasicrystals. We discuss in detail the high-strength rapid-solidified nanoquasicrystalline composites, the challenges involved in their manufacturing processes and their properties. We also bring the latest findings on the fabrication of Al-matrix composites reinforced with quasicrystals by powder metallurgy and by conventional metallurgical processes. We show that substantial developments were made over the last decade and discuss possible future studies that may result from these recent findings.
Colonialism came late to northern Guatemala. The Spanish began to establish missions in the Peten Lakes region in the early 1700s, nearly 200 years after initial contact with the Mayas. Excavations in 2011–2012 at the Mission San Bernabé revealed European goods, nonnative animal species, and burial patterns that marked a new lifestyle. Who lived at the Mission San Bernabé, and where did they come from? The Spanish resettled indigenous populations to facilitate the colonization process; however, isotopic data are inconsistent with large population movements. Instead, strontium and oxygen isotope values in the tooth enamel and bones of individuals buried at the mission suggest a mostly local population. The data suggest in-migration from Belize, a region under nominal Spanish control, but with pre-Hispanic ties to the Peten. Changes did not come from migrants crossing a border; instead, the border itself moved and brought the colonial world to the Peten Mayas.
To assess availability, variety, price and quality of different food products in a convenience sample of supermarkets in Germany and the USA.
Cross-sectional study using an adapted version of the Bridging the Gap Food Store Observation Form.
Information on availability, quality, price and variety of selected food products in eight German and seven US supermarkets (discount and full service) was obtained and compared by country.
A general tendency for lower prices of fruits and vegetables in Germany was observed, while produce quality and variety did not seem to differ between countries, with the exception of the variety of some vegetables such as tomatoes. Chips and cereals did not differ significantly in variety nor price. In both countries, high energy-dense foods were lower in energy costs than lower energy-dense foods.
The influence of food prices and availability on consumption should be further explored, including the impact of country differences.
We implemented universal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing of patients undergoing surgical procedures as a means to conserve personal protective equipment (PPE). The rate of asymptomatic coronavirus disease 2019 (COVID-19) was <0.5%, which suggests that early local public health interventions were successful. Although our protocol was resource intensive, it prevented exposures to healthcare team members.
Surface waves called meniscus waves often appear in systems that are close to the capillary length scale. Since the meniscus shape determines the form of the meniscus waves, the resulting streaming circulation has features distinct from those caused by other capillary–gravity waves recently reported in the literature. In the present study, we produce symmetric and antisymmetric meniscus shapes by controlling boundary wettability and excite meniscus waves by oscillating the meniscus vertically. The symmetric and antisymmetric configurations produce different surface capillary–gravity wave modes and streaming flow structures. The root-mean-square speed of the streaming circulation increases with the second power of the forcing amplitude in both configurations. The flow symmetry of streaming circulation is retained under the symmetric meniscus, while it is lost under the antisymmetric meniscus. The streaming circulation pattern beneath the meniscus observed in our experiments is qualitatively explained using the method introduced by Nicolás & Vega (Fluid Dyn. Res., vol. 32 (4), 2003, pp. 119–139) and Gordillo & Mujica (J. Fluid Mech., vol. 754, 2014, pp. 590–604).
This study aimed to assess whether increasing operative experience results in better surgical outcomes in endoscopic middle-ear surgery.
A retrospective single-institution cohort study was performed. Patients underwent endoscopic tympanoplasty between May 2013 and April 2019 performed by the senior surgeon or a trainee surgeon under direct supervision from the senior surgeon. Following data collection, statistical analysis compared success rates between early (learning curve) surgical procedures and later (experienced) tympanoplasties.
In total, 157 patients (86 male, 71 female), with a mean age of 41.6 years, were included. The patients were followed up for an average of 43.2 weeks. The overall primary closure rate was 90.0 per cent.
This study demonstrates an early learning curve for endoscopic ear surgery that improves with surgical experience. Adoption of the endoscopic technique did not impair the success rates of tympanoplasty.
Despite considerable advances in the evidence-based treatments, the long-term management of depressive disorders remains a challenge. Many depressive disorders follow a chronic or recurrent course. Substantial proportions of patients end treatment, especially those with residual symptoms, leave treatment with considerable risk for relapses and/or persistent psychosocial impairment. Long-term strategies are needed that can effectively help patients minimize the negative consequences of their illness without imposing a too much of an extra burden. We present the protocol of a multi-center RCT on the efficacy of an Internet based disease management strategy for the specific health conditions in recurrent depression. 234 patients who are treated for their minimum third episode of a major depression (MD) in one of the six participating centers will participate post-treatment in one of two internet delivered interventions or usual care alone. The interventions continue over 12 months and consist of supportive monitoring, an online forum for peer support, and individual crisis management either with or without personal clinical support. Primary outcome of the trial is the ratio of “well” to “unwell weeks” over a 24-month observation period after index treatment assessed with the Longitudinal Interval Follow-Up Evaluation. We would like to discuss the new options that information and communication technology offers for long-term disease management strategies for patients with recurrent depression and invite for a discussion about strategies for other chronic mental disorders.
Studies into social cognition in psychiatric disorders have recently been expanded to address the questions whether or not “theory of mind” (ToM), that is, the ability to represent own and others’ mental states, is impaired in bipolar affective disorder (BPD).
Results have been mixed so far, mainly due to possible confounding effects of neurocognition, as well as, clinical factors such as acuity and current mood. Here, we explored ToM and its associations with neurocognitive functioning in BPD.
33 patients with bipolar I disorder (of which 12 were currently depressed, 10 manic, and 11 remitted) and 29 healthy controls were assessed using a test battery that was identical to the one that was used in previous studies into schizophrenia, comprising diverse neurocognitive tasks, including measures of intelligence, executive functioning, and ToM tasks.
The bipolar patient group as a whole, as well as all three clinical subgroups, were impaired on all measures of ToM relative to controls, but did not differ from each other in most ToM scores. Patients’ poorer performance on executive tasks did not fully explain ToM differences between patients and controls, suggesting a partially selective ToM deficit in BPD.
Patients with BPD are impaired in ToM, partially independent of other cognitive dysfunctions and current mood.
Hippocampal cavities (HcC) are frequent findings in brain MRIs of elderly subjects. The prevalence, evolution and impact on cognitive performance of these cavities are unclear. Our study therefore aims at providing data on prevalence, morphological evolution and clinical significance of HcC. We used a population-based sample of nondemented elderly subjects aged 75–85 and a comparison group with Alzheimer's disease for cross-sectional analysis. All nondemented subjects were included in a prospective study (mean follow-up 3.2 years). HcC numbers and volume were recorded from volumetric T1w MRI scans. Serial MRIs were performed for a subgroup of subjects. Cognitive functions were assessed by SIDAM and CDR. Hippocampal and brain volume, medial temporal lobe atrophy, white matter lesions, ApoE genotype and vascular risk factors were considered as confounders. The prevalence of HcC in our sample was approx. 60% with no differences between cognitive groups. HcC volume was found to be a predictor of short-term episodic memory performance. The effect of HcC volume was non-linear with the highest risk for decrease in short-term memory associated with the smallest HcC volumes. Mean HcC number and volume remained stable during follow-up. However, we provide anectodal evidence for both cases with increase and decrease of HcC volume over time. In conclusion, small HcC may be an independent risk factor for decline in short term episodic memory performance in elderly subjects.
Minor motor and sensory deficits or neurological soft signs (NSS) are frequently found in patients with schizophrenia at any stage of their illness. Numerous structural magnetic resonance imaging (MRI) studies repeatedly revealed accentuated thinning of cortical mantle in schizophrenia. However, whether NSS are related to alterations of cortical thickness has so far remained mostly unexplored.
Whole brain high-resolution MRI at 3 Tesla was used to investigate cortical thickness in twenty five patients with recent-onset schizophrenia. Cortical reconstruction was performed with the Freesurfer image analysis suite. NSS were examined on the Heidelberg Scale after remission of acute symptoms and related to cortical thickness. Age, education, medication and duration of illness were considered as potential confounders.
Higher NSS scores were associated with decreased cortical thickness in multiple areas. Significant correlations were found in somatosensory and primary motor cortex, pre-motor area and temporal lobe. Our results confirm the hypothesis of significant relationship between alterations of cortical thickness and the extent of NSS in schizophrenia.
Our findings provide new insights into the association of NSS with brain morphometric alterations and an involvement of cortical thickness in schizophrenia.
The Antarctic Impulsive Transient Antenna (ANITA) balloon experiment was designed to detect radio signals initiated by high-energy neutrinos and cosmic ray (CR) air showers. These signals are typically discriminated by the polarization and phase inversions of the radio signal. The reflected signal from CRs suffer phase inversion compared to a direct ‘tau neutrino’ event. In this paper, we study subsurface reflection, which can occur without phase inversion, in the context of the two anomalous up-going events reported by ANITA. It is found that subsurface layers and firn density inversions may plausibly account for the events, while ice fabric layers and wind ablation crusts could also play a role. This hypothesis can be tested with radar surveying of the Antarctic region in the vicinity of the anomalous ANITA events. Future experiments should not use phase inversion as a sole criterion to discriminate between down-going and up-going events, unless the subsurface reflection properties are well understood.