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The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to be used to evaluate specific aspects of the instrument performance of both X-ray and neutron powder diffractometers. This report describes SRM 640f, the seventh generation of this powder diffraction SRM, which is designed to be used primarily for calibrating powder diffractometers with respect to line position; it also can be used for the determination of the instrument profile function. It is certified with respect to the lattice parameter and consists of approximately 7.5 g of silicon powder prepared to minimize line broadening. A NIST-built diffractometer, incorporating many advanced design features, was used to certify the lattice parameter of the Si powder. Both statistical and systematic uncertainties have been assigned to yield a certified value for the lattice parameter at 22.5 °C of a = 0.5431144 ± 0.000008 nm.
Large prospective observational studies have cast doubt on the common assumption that endovascular thrombectomy (EVT) is superior to intravenous thrombolysis for patients with acute basilar artery occlusion (BAO). The purpose of this study was to retrospectively review our experience for patients with BAO undergoing EVT with modern endovascular devices.
All consecutive patients undergoing EVT with either a second-generation stent retriever or direct aspiration thrombectomy for BAO at our regional stroke center from January 1, 2013 to March 1, 2019 were included. The primary outcome measure was functional outcome at 1 month using the modified Rankin Scale (mRS) score. Multivariable logistic regression was used to assess the association between patient characteristics and dichotomized mRS.
A total of 43 consecutive patients underwent EVT for BAO. The average age was 67 years with 61% male patients. Overall, 37% (16/43) of patients achieved good functional outcome. Successful reperfusion was achieved in 72% (31/43) of cases. The median (interquartile range) stroke onset to treatment time was 420 (270–639) minutes (7 hours) for all patients. The procedure-related complication rate was 9% (4/43). On multivariate analysis, posterior circulation Alberta stroke program early computed tomography score and Basilar Artery on Computed Tomography Angiography score were associated with improved functional outcome.
EVT appears to be safe and feasible in patients with BAO. Our finding that time to treatment and successful reperfusion were not associated with improved outcome is likely due to including patients with established infarcts. Given the variability of collaterals in the posterior circulation, the paradigm of utilizing a tissue window may assist in patient selection for EVT. Magnetic resonance imaging may be a reasonable option to determine the extent of ischemia in certain situations.
Recent investigations now suggest that cerebrovascular reactivity (CVR) is impaired in Alzheimer’s disease (AD) and may underpin part of the disease’s neurovascular component. However, our understanding of the relationship between the magnitude of CVR, the speed of cerebrovascular response, and the progression of AD is still limited. This is especially true in patients with mild cognitive impairment (MCI), which is recognized as an intermediate stage between normal aging and dementia. The purpose of this study was to investigate AD and MCI patients by mapping repeatable and accurate measures of cerebrovascular function, namely the magnitude and speed of cerebrovascular response (τ) to a vasoactive stimulus in key predilection sites for vascular dysfunction in AD.
Thirty-three subjects (age range: 52–83 years, 20 males) were prospectively recruited. CVR and τ were assessed using blood oxygen level-dependent MRI during a standardized carbon dioxide stimulus. Temporal and parietal cortical regions of interest (ROIs) were generated from anatomical images using the FreeSurfer image analysis suite.
Of 33 subjects recruited, 3 individuals were excluded, leaving 30 subjects for analysis, consisting of 6 individuals with early AD, 11 individuals with MCI, and 13 older healthy controls (HCs). τ was found to be significantly higher in the AD group compared to the HC group in both the temporal (p = 0.03) and parietal cortex (p = 0.01) following a one-way ANCOVA correcting for age and microangiopathy scoring and a Bonferroni post-hoc correction.
The study findings suggest that AD is associated with a slowing of the cerebrovascular response in the temporal and parietal cortices.
The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to evaluate specific aspects of instrument performance of both X-ray and neutron powder diffractometers. This report describes SRM 660c, the fourth generation of this powder diffraction SRM, which is used primarily for calibrating powder diffractometers with respect to line position and line shape for the determination of the instrument profile function (IPF). It is certified with respect to lattice parameter and consists of approximately 6 g of lanthanum hexaboride (LaB6) powder. So that this SRM would be applicable for the neutron diffraction community, the powder was prepared from an isotopically enriched 11B precursor material. The microstructure of the LaB6 powder was engineered specifically to yield a crystallite size above that where size broadening is typically observed and to minimize the crystallographic defects that lead to strain broadening. A NIST-built diffractometer, incorporating many advanced design features, was used to certify the lattice parameter of the LaB6 powder. Both Type A, statistical, and Type B, systematic, uncertainties have been assigned to yield a certified value for the lattice parameter at 22.5 °C of a = 0.415 682 6 ± 0.000 008 nm (95% confidence).
Early irritability predicts a broad spectrum of psychopathology spanning both internalizing and externalizing disorders, rather than any particular disorder or group of disorders (i.e. multifinality). Very few studies, however, have examined the developmental mechanisms by which it leads to such phenotypically diverse outcomes. We examined whether variation in the diurnal pattern of cortisol moderates developmental pathways between preschool irritability and the subsequent emergence of internalizing and externalizing symptoms 9 years later.
When children were 3 years old, mothers were interviewed about children's irritability and completed questionnaires about their children's psychopathology. Six years later, children collected saliva samples at wake-up and bedtime on three consecutive days. Diurnal cortisol patterns were modeled as latent difference scores between evening and morning samples. When children were approximately 12 years old, mothers again completed questionnaires about their children's psychopathology.
Among children with higher levels of irritability at age 3, a steeper diurnal cortisol slope at age 9 predicted greater internalizing symptoms and irritability at age 12, whereas a blunted slope at age 9 predicted greater externalizing symptoms at age 12, adjusting for baseline and concurrent symptoms.
Our results suggest that variation in stress system functioning can predict and differentiate developmental trajectories of early irritability that are relatively more internalizing v. those in which externalizing symptoms dominate in pre-adolescence.
The Comprehensive Assessment of Neurodegeneration and Dementia (COMPASS-ND) cohort study of the Canadian Consortium on Neurodegeneration in Aging (CCNA) is a national initiative to catalyze research on dementia, set up to support the research agendas of CCNA teams. This cross-country longitudinal cohort of 2310 deeply phenotyped subjects with various forms of dementia and mild memory loss or concerns, along with cognitively intact elderly subjects, will test hypotheses generated by these teams.
The COMPASS-ND protocol, initial grant proposal for funding, fifth semi-annual CCNA Progress Report submitted to the Canadian Institutes of Health Research December 2017, and other documents supplemented by modifications made and lessons learned after implementation were used by the authors to create the description of the study provided here.
The CCNA COMPASS-ND cohort includes participants from across Canada with various cognitive conditions associated with or at risk of neurodegenerative diseases. They will undergo a wide range of experimental, clinical, imaging, and genetic investigation to specifically address the causes, diagnosis, treatment, and prevention of these conditions in the aging population. Data derived from clinical and cognitive assessments, biospecimens, brain imaging, genetics, and brain donations will be used to test hypotheses generated by CCNA research teams and other Canadian researchers. The study is the most comprehensive and ambitious Canadian study of dementia. Initial data posting occurred in 2018, with the full cohort to be accrued by 2020.
Availability of data from the COMPASS-ND study will provide a major stimulus for dementia research in Canada in the coming years.
Employability assessment was developed to help claims professionals decide total and permanent disability insurance claims, yet it has not been empirically evaluated. This descriptive study sought formative knowledge about employability assessment from claims professionals working in the multibillion-dollar Australian life insurance total and permanent disability market. Claims assessors (n = 53) and technical advisors (n = 51) responded to a nationwide online survey. Participants found employability assessment was cost effective and very useful in deciding claims. Having an objective, realistic, and clear picture of a claimant’s employment prospects was important. Highly rated components of employability assessment included transferable skills analysis; summary of education, training and experience; job match rationale; and labour market analysis with employer contact. Face-to-face claimant interviews were favoured by 56% of participants, particularly when there was legal involvement. Standardised provider training and certification were recommended to improve report quality and withstand scrutiny of the courts. Billing time estimates are higher than extant costs for assessment tasks. More than half (56%) the participants considered rehabilitation counsellors were best qualified to conduct employability assessments. The study findings contribute new knowledge to this emergent field and point to further research into quality and cost of employability assessment, and provider accreditation.
The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to address specific aspects of the performance of X-ray powder diffraction instruments. This report describes SRM 1879b, the third generation of this powder diffraction SRM. SRM 1879b is intended for use in the preparation of calibration standards for the quantitative analyses of cristobalite by X-ray powder diffraction in accordance with National Institute for Occupational Safety and Health (NIOSH) Analytical Method 7500, or equivalent. A unit of SRM 1879b consists of approximately 5 g of cristobalite powder bottled in an argon atmosphere. It is certified with respect to crystalline phase purity, or amorphous phase content, and lattice parameter. Neutron powder diffraction, both time-of-flight and constant wavelength, was used to certify the phase purity using SRM 676a as an internal standard. A NIST-built diffractometer, incorporating many advanced design features was used for certification measurements for lattice parameters.
To identify home environment factors associated with toddler dietary behaviours using ecological momentary assessment (EMA).
Home environment and toddler’s diet were assessed by mothers through EMA (random beeps over ≤8 d and a brief survey). Dietary outcomes were fruit/vegetable consumption, eating episode (‘snack’ v. ‘meal’) and sugar-sweetened beverage (SSB) consumption. Home environment factors included interacting with mother, eating alone/with others, eating in a high chair/chair at the table, watching television and movement/translocation. Multilevel logistic mixed-effects regression models assessed both within- (individual toddlers across time) and between- (toddlers-on-average) subject effects.
Low-income mother–toddler dyads (n 277).
Urban and suburban Maryland, USA.
EMA captured eating/drinking episodes for 249/277 (89·9 %) toddlers (883 eating episodes, 1586 drinking episodes). Toddlers-on-average were more likely (adjusted OR, P value) to eat fruit/vegetables when not moving around (0·43, P=0·043), eat with the television off (0·33, P<0·001) and eat in a high chair/chair (3·38, P<0·001); no within-subject effects were shown. For eating episodes, both toddlers-on-average and individual toddlers were more likely to eat snacks when not in a high chair/chair (0·13, P<0·001 and 0·06, P<0·001, respectively) and when eating alone (0·30, P<0·001 and 0·31, P<0·001, respectively). Also, individual toddlers were more likely to eat snacks when moving around (3·61, P<0·001). Toddlers-on-average were more likely to consume SSB when not in a high chair/chair (0·21, P=0·001), eating alone (0·38, P=0·047) or during a snacking episode (v. a meal: 3·96, P=0·012); no within-subject effects shown.
Factors in the home environment are associated with dietary behaviours among toddlers. Understanding the interplay between the home environment and toddler diet can inform future paediatric dietary recommendations.
Phased Array Feed (PAF) technology is the next major advancement in radio astronomy in terms of combining high sensitivity and large field of view. The Focal L-band Array for the Green Bank Telescope (FLAG) is one of the most sensitive PAFs developed so far. It consists of 19 dual-polarization elements mounted on a prime focus dewar resulting in seven beams on the sky. Its unprecedented system temperature of ~17 K will lead to a 3 fold increase in pulsar survey speeds as compared to contemporary single pixel feeds. Early science observations were conducted in a recently concluded commissioning phase of the FLAG where we clearly demonstrated its science capabilities. We observed a selection of normal and millisecond pulsars and detected giant pulses from PSR B1937+21.
This paper presents latest thinking from the Institute and Faculty of Actuaries’ Model Risk Working Party and follows on from their Phase I work, Model Risk: Daring to Open the Black Box. This is a more practical paper and presents the contributors’ experiences of model risk gained from a wide range of financial and non-financial organisations with suggestions for good practice and proven methods to reduce model risk. After a recap of the Phase I work, examples of model risk communication are given covering communication: to the Board; to the regulator; and to external stakeholders. We present a practical framework for model risk management and quantification with examples of the key actors, processes and cultural challenge. Lessons learned are then presented from other industries that make extensive use of models and include the weather forecasting, software and aerospace industries. Finally, a series of case studies in practical model risk management and mitigation are presented from the contributors’ own experiences covering primarily financial services.
The aim of this analysis was to test if changes in insomnia symptoms and global sleep quality are associated with coinciding changes in depressed mood among older adults. We report on results yielded from secondary analysis of longitudinal data from a clinical trial of older adults (N = 49) aged 55 to 80 years who reported at least moderate levels of sleep problems. All measures were collected at baseline and after the trial ten weeks later. We computed change scores for two separate measures of disturbed sleep, the Athens Insomnia Scale (AIS) and the Pittsburgh Sleep Quality Index (PSQI), and tested their association with change in depressed mood (Beck Depression Inventory-II; BDI-II) in two separate linear regression models adjusted for biological covariates related to sleep (sex, age, body mass index, and NF-κB as a biological marker previously correlated with insomnia and depression). Change in AIS scores was associated with change in BDI-II scores (β = 0.38, p < 0.01). Change in PSQI scores was not significantly associated with change in BDI-II scores (β = 0.17, p = 0.26). Our findings suggest that improvements over ten weeks in insomnia symptoms rather than global sleep quality coincide with improvement in depressed mood among older adults.
Electronic health records (EHRs) provide great promise for identifying cohorts and enhancing research recruitment. Such approaches are sorely needed, but there are few descriptions in the literature of prevailing practices to guide their use. A multidisciplinary workgroup was formed to examine current practices in the use of EHRs in recruitment and to propose future directions. The group surveyed consortium members regarding current practices. Over 98% of the Clinical and Translational Science Award Consortium responded to the survey. Brokered and self-service data warehouse access are in early or full operation at 94% and 92% of institutions, respectively, whereas, EHR alerts to providers and to research teams are at 45% and 48%, respectively, and use of patient portals for research is at 20%. However, these percentages increase significantly to 88% and above if planning and exploratory work were considered cumulatively. For most approaches, implementation reflected perceived demand. Regulatory and workflow processes were similarly varied, and many respondents described substantive restrictions arising from logistical constraints and limitations on collaboration and data sharing. Survey results reflect wide variation in implementation and approach, and point to strong need for comparative research and development of best practices to protect patients and facilitate interinstitutional collaboration and multisite research.
Treerow vegetation abundance and biodiversity were measured in response to six orchard floor management strategies in organic peach in northern Utah for three growing seasons. A total of 32 weed species were observed in the treerow; the most common were field bindweed, dandelion, perennial grasses (e.g., red fescue and ryegrass), clovers, and prickly lettuce. Weed biomass was two to five times greater in unmanaged (living mulch) than in manipulated treatments. Tillage greatly reduced weeds for approximately one month; however, vegetation rebounded midseason. Tillage selected for species adapted to disturbance, such as common purslane and field bindweed. Straw mulch provided equivalent weed suppression to tillage in the early season. Straw required annual reapplication with material costs, labor, and weed-seed contamination (e.g., volunteer grains and quackgrass) as disadvantages. Plastic fabric mulch reduced weeds the most, but had high initial costs and required seasonal maintenance. Weed biomass declined within seasons and across the three years of the study, likely due to tree canopy shading. Neither birdsfoot trefoil nor a perennial grass mixture planted in the alleyways influenced treerow weeds. Our results demonstrate several viable alternatives to tillage for weed management in treerows of organic peach orchards in the Intermountain West.
Far-UV photons (FUV, E < 13.6 eV) from hot massive stars regulate, or at least influence, the heating, ionization, and chemistry of most of the neutral interstellar medium (H i and H2 clouds). Investigating the interaction between FUV radiation and interstellar matter (molecules, atoms and grains) thus plays an important role in astrochemistry.
The Orion Bar, an interface region between the Orion A molecular cloud and the H ii region around the Trapezium cluster, is a textbook example of a strongly illuminated dense PDR (photodissociation region). The Bar is illuminated by a FUV field of a few 104 times the mean interstellar radiation field. Because of its proximity and nearly edge-on orientation, it provides a very good template to investigate the chemical content, structure, and dynamics of a strongly irradiated molecular cloud edge. We have used ALMA to mosaic a small field of the Bar where the critical transition from atomic to molecular gas takes place. These observations provide an unprecedented sharp view of this transition layer (≲ 1″ resolution or ≲ 414 AU). The resulting images (so far in the rotational emission of CO, HCO+, H13CO+, SO+, SO, and reactive ions SH+ and HOC+) show the small-scale structure in gas density and temperature, and the steep abundance gradients. The images reveal a pattern of high-density substructures, photo-ablative gas flows and instabilities at the edge of the molecular cloud. These first ALMA images thus show a more complex morphology than the classical clump/interclump static model of a PDR.
In order to quantify the chemical content in strongly FUV-irradiated gas, we have also used the IRAM-30 m telescope to carry out a complete line-survey of the illuminated edge of the Bar in the millimeter domain. Our observations reveal the presence of complex organic molecules (and precursors) that were not expected in such a harsh environment. In particular, we have reported the first detection of the unstable cis conformer of formic acid (HCOOH) in the ISM. The energy barrier to internal rotation (the conversion from trans to cis) is approximately 4827 cm−1 (≈7000 K). Hence, this detection is surprising. The low inferred trans-to-cis abundance ratio of 2.8±1.0 supports a photoswitching mechanism: a given conformer absorbs a FUV stellar photon that radiatively excites the molecule to electronic states above the interconversion barrier. Subsequent fluorescent decay leaves the molecule in a different conformer form. This mechanism, which we have specifically studied with ab initio quantum calculations, was not considered so far in astrochemistry although it can affect the structure of a variety of molecules in PDRs.
To determine whether living in a food swamp (≥4 corner stores within 0·40 km (0·25 miles) of home) or a food desert (generally, no supermarket or access to healthy foods) is associated with consumption of snacks/desserts or fruits/vegetables, and if neighbourhood-level socio-economic status (SES) confounds relationships.
Cross-sectional. Assessments included diet (Youth/Adolescent FFQ, skewed dietary variables normalized) and measured height/weight (BMI-for-age percentiles/Z-scores calculated). A geographic information system geocoded home addresses and mapped food deserts/food swamps. Associations examined using multiple linear regression (MLR) models adjusting for age and BMI-for-age Z-score.
Baltimore City, MD, USA.
Early adolescent girls (6th/7th grade, n 634; mean age 12·1 years; 90·7 % African American; 52·4 % overweight/obese), recruited from twenty-two urban, low-income schools.
Girls’ consumption of fruit, vegetables and snacks/desserts: 1·2, 1·7 and 3·4 servings/d, respectively. Girls’ food environment: 10·4 % food desert only, 19·1 % food swamp only, 16·1 % both food desert/swamp and 54·4 % neither food desert/swamp. Average median neighbourhood-level household income: $US 35 298. In MLR models, girls living in both food deserts/swamps consumed additional servings of snacks/desserts v. girls living in neither (β=0·13, P=0·029; 3·8 v. 3·2 servings/d). Specifically, girls living in food swamps consumed more snacks/desserts than girls who did not (β=0·16, P=0·003; 3·7 v. 3·1 servings/d), with no confounding effect of neighbourhood-level SES. No associations were identified with food deserts or consumption of fruits/vegetables.
Early adolescent girls living in food swamps consumed more snacks/desserts than girls not living in food swamps. Dietary interventions should consider the built environment/food access when addressing adolescent dietary behaviours.
Virkisjökull is a rapidly retreating outlet glacier draining the western flanks of Öræfajökull in SE Iceland. Since 2011 there have been continuous measurements of flow in the proglacial meltwater channel and regular campaigns to sample stable isotopes δ2H and δ18O from the river, ice, moraine springs and groundwater. The stable isotopes provide reliable end members for glacial ice and shallow groundwater. Analysis of data from 2011 to 2014 indicates that although ice and snowmelt dominate summer riverflow (mean 5.3–7.9 m3 s−1), significant flow is also observed in winter (mean 1.6–2.4 m3 s−1) due primarily to ongoing glacier icemelt. The stable isotope data demonstrate that the influence of groundwater discharge from moraines and the sandur aquifer increases during winter and forms a small (15–20%) consistent source of baseflow to the river. The similarity of hydrological response across seasons reflects a highly efficient glacial drainage system, which makes use of a series of permanent englacial channels within active and buried ice throughout the year. The study has shown that the development of an efficient year round drainage network within the lower part of the glacier has been coincident with the stagnation and subsequent rapid retreat of the glacier.