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.
We present a survey of modeling techniques used to describe and predict architected cellular metamaterials, and to optimize their topology and geometry toward tailoring their mechanical properties such as stiffness, strength, fracture toughness, and energy absorption. Architectures of interest include truss-, plate-, and shell-based networks with and without periodicity, whose effective mechanical behavior is simulated by tools such as classical finite elements, further scale-bridging techniques such as homogenization and concurrent scale-coupling, and effective continuum descriptions of the underlying discrete networks. In addition to summarizing advances in applying the latter techniques to improve the properties of metamaterials and featuring prominent examples of structure–property relations achieved this way, we also present recently introduced techniques to improve the optimization process toward a full exploitation of the available design space, accounting for both linear and nonlinear material behavior.
Basal ice of glaciers and ice sheets frequently contains a well-developed stratification of distinct, semi-continuous, alternating layers of debris-poor and debris-rich ice. Here, the nature and distribution of shear within stratified basal ice are assessed through the anisotropy of magnetic susceptibility (AMS) of samples collected from Matanuska Glacier, Alaska. Generally, the AMS reveals consistent moderate-to-strong fabrics reflecting simple shear in the direction of ice flow; however, AMS is also dependent upon debris content and morphology. While sample anisotropy is statistically similar throughout the sampled section, debris-rich basal ice composed of semi-continuous mm-scale layers (the stratified facies) possesses well-defined triaxial to oblate fabrics reflecting shear in the direction of ice flow, whereas debris-poor ice containing mm-scale star-shaped silt aggregates (the suspended facies) possesses nearly isotropic fabrics. Thus, deformation within the stratified basal ice appears concentrated in debris-rich layers, likely the result of decreased crystal size and greater availability of unfrozen water associated with high debris content. These results suggest that variations in debris-content over small spatial scales influence ice rheology and deformation in the basal zone.
We have observed the G23 field of the Galaxy AndMass Assembly (GAMA) survey using the Australian Square Kilometre Array Pathfinder (ASKAP) in its commissioning phase to validate the performance of the telescope and to characterise the detected galaxy populations. This observation covers ~48 deg2 with synthesised beam of 32.7 arcsec by 17.8 arcsec at 936MHz, and ~39 deg2 with synthesised beam of 15.8 arcsec by 12.0 arcsec at 1320MHz. At both frequencies, the root-mean-square (r.m.s.) noise is ~0.1 mJy/beam. We combine these radio observations with the GAMA galaxy data, which includes spectroscopy of galaxies that are i-band selected with a magnitude limit of 19.2. Wide-field Infrared Survey Explorer (WISE) infrared (IR) photometry is used to determine which galaxies host an active galactic nucleus (AGN). In properties including source counts, mass distributions, and IR versus radio luminosity relation, the ASKAP-detected radio sources behave as expected. Radio galaxies have higher stellar mass and luminosity in IR, optical, and UV than other galaxies. We apply optical and IR AGN diagnostics and find that they disagree for ~30% of the galaxies in our sample. We suggest possible causes for the disagreement. Some cases can be explained by optical extinction of the AGN, but for more than half of the cases we do not find a clear explanation. Radio sources aremore likely (~6%) to have an AGN than radio quiet galaxies (~1%), but the majority of AGN are not detected in radio at this sensitivity.
Perceived discrimination (PD) is reliably and strongly associated with partisan identity (PID) among US immigrant minorities such as Latinos and Asian Americans. Yet whether PD causes PID remains unclear, since it is possible that partisanship influences perceptions of discrimination or that other factors drive the observed association. Here, we assess the causal influence of group-level PD on PID using five experiments with Latino and Asian American adults. These experiments varied in important ways: they took place inside and outside the lab, occurred prior to and during Donald Trump’s presidential campaign, and tested different manifestations of PD and partisan attitudes (total n = 2,528). These efforts point to a simple but unexpected conclusion: our experiments and operationalizations do not support the claim that group-targeted PD directly causes PID. These results have important implications for understanding partisanship among immigrants and their co-ethnics and the political incorporation of Latinos and Asian Americans.
This study examined effects of risk factors in multiple domains measured in preschool and kindergarten on age 6 depression symptoms, and on changes in symptom levels between ages 4 and 6. Two models were examined in a large, diverse (N = 796) community sample of children and parents. Risk variables included SES, stress, conflict, parental depression, parental hostility, support, scaffolding, child negative affect (NA), effortful control (EC), sensory regulation (SR), and attachment security. Model 1 included effects of risk factors at ages 4 and 5 on child depression symptoms at age 6. Model 2 also included depression symptoms at all three ages to examine changes in these symptoms. Model 1 revealed that age 4 and 5 parental depression, NA, EC, and SR predicted age 6 child depression levels, Several age 4 variables had indirect pathways to age 6 depression via age 5 EC. Model 2 revealed that preschool depression was the only age 4 variable, and EC and SR were the only age 5 variables that significantly predicted increases in age 6 depression. These findings highlight the role of self-regulation in child depression and suggest that targeting self-regulation may be an effective prevention and intervention strategy.
In sub-Saharan Africa (SSA), the association of crops and livestock in mixed farming systems generally benefits both enterprises. This paper focuses on the main contributions of livestock to crop production: the use of manure and animal draught power to produce crops and the investment of income from livestock into technologies that benefit crop production. In low-input, grazing-based feeding operations, manure is a vital soil fertility amendment. In these systems, penning livestock overnight on fields, fallow between cropping periods, returns both manure and urine to the soil and results in much higher crop yields than if manure only is gathered from stalls and spread onto fields. However, most farmers have insufficient manure to sustain food production. Nutrient harvests often exceed nutrient inputs, requiring a much greater use of fertilizers to arrest soil nutrient depletion. The opposite may be true for mixed farming where livestock are given food in confinement. In these emerging systems, the continuous importation of food (and fertilizer) can result in nutrient surpluses with subsequent soil nutrient build-up and loss. The contribution of animal power to crop production is relatively new in Africa. Animal power affects the amount of land cultivated by farmers, crop selection, the yield per farm and per ha, and on the participation and work load of people (family members and outside labour) involved in crop production and its associated activities. In addition to the impacts of manure and draught power on crop production, income derived from livestock is often invested in inputs that enhance crop production. At the ‘micro’ level, livestock income influences crop production (1) directly by allowing households to invest in productive inputs such as fertilizer, hired labour, and carts and (2) indirectly by allowing poor households to improve their nutritional status and, therefore, the productivity of their most important resource, their own labour. At the ‘macro’ level, increased livestock exports have a large stimulating effect on the demand for locally produced goods and services, particularly basic food crops. Thus, increasing the productivity of the livestock sector, including an emphasis on the policy and institutional environment influencing marketing and trade, is an important element of a development strategy focused on stimulating economic growth and alleviating poverty.
There is variation regarding the use of surgery and interventional radiological techniques in the management of epistaxis. This review evaluates the effectiveness of surgical artery ligation compared to direct treatments (nasal packing, cautery), and that of embolisation compared to direct treatments and surgery.
A systematic review of the literature was performed using a standardised published methodology and custom database search strategy.
Thirty-seven studies were identified relating to surgery, and 34 articles relating to interventional radiology. For patients with refractory epistaxis, endoscopic sphenopalatine artery ligation had the most favourable adverse effect profile and success rate compared to other forms of surgical artery ligation. Endoscopic sphenopalatine artery ligation and embolisation had similar success rates (73–100 per cent and 75–92 per cent, respectively), although embolisation was associated with more serious adverse effects (risk of stroke, 1.1–1.5 per cent). No articles directly compared the two techniques.
Trials comparing endoscopic sphenopalatine artery ligation to embolisation are required to better evaluate the clinical and economic effects of intervention in epistaxis.
Evidence regarding the seasonality of urinary tract infection (UTI) consultations in primary care is conflicting and methodologically poor. To our knowledge, this is the first study to determine whether this seasonality exists in the UK, identify the peak months and describe seasonality by age. The monthly number of UTI consultations (N = 992 803) and nitrofurantoin and trimethoprim prescriptions (N = 1 719 416) during 2008–2015 was extracted from The Health Improvement Network (THIN), a large nationally representative UK dataset of electronic patient records. Negative binomial regression models were fitted to these data to investigate seasonal fluctuations by age group (14–17, 18–24, 25–45, 46–69, 70–84, 85+) and by sex, accounting for a change in the rate of UTI over the study period. A September to November peak in UTI consultation incidence was observed for ages 14–69. This seasonality progressively faded in older age groups and no seasonality was found in individuals aged 85+, in whom UTIs were most common. UTIs were rare in males but followed a similar seasonal pattern than in females. We show strong evidence of an autumnal seasonality for UTIs in individuals under 70 years of age and a lack of seasonality in the very old. These findings should provide helpful information when interpreting surveillance reports and the results of interventions against UTI.
The Taipan galaxy survey (hereafter simply ‘Taipan’) is a multi-object spectroscopic survey starting in 2017 that will cover 2π steradians over the southern sky (δ ≲ 10°, |b| ≳ 10°), and obtain optical spectra for about two million galaxies out to z < 0.4. Taipan will use the newly refurbished 1.2-m UK Schmidt Telescope at Siding Spring Observatory with the new TAIPAN instrument, which includes an innovative ‘Starbugs’ positioning system capable of rapidly and simultaneously deploying up to 150 spectroscopic fibres (and up to 300 with a proposed upgrade) over the 6° diameter focal plane, and a purpose-built spectrograph operating in the range from 370 to 870 nm with resolving power R ≳ 2000. The main scientific goals of Taipan are (i) to measure the distance scale of the Universe (primarily governed by the local expansion rate, H0) to 1% precision, and the growth rate of structure to 5%; (ii) to make the most extensive map yet constructed of the total mass distribution and motions in the local Universe, using peculiar velocities based on improved Fundamental Plane distances, which will enable sensitive tests of gravitational physics; and (iii) to deliver a legacy sample of low-redshift galaxies as a unique laboratory for studying galaxy evolution as a function of dark matter halo and stellar mass and environment. The final survey, which will be completed within 5 yrs, will consist of a complete magnitude-limited sample (i ⩽ 17) of about 1.2 × 106 galaxies supplemented by an extension to higher redshifts and fainter magnitudes (i ⩽ 18.1) of a luminous red galaxy sample of about 0.8 × 106 galaxies. Observations and data processing will be carried out remotely and in a fully automated way, using a purpose-built automated ‘virtual observer’ software and an automated data reduction pipeline. The Taipan survey is deliberately designed to maximise its legacy value by complementing and enhancing current and planned surveys of the southern sky at wavelengths from the optical to the radio; it will become the primary redshift and optical spectroscopic reference catalogue for the local extragalactic Universe in the southern sky for the coming decade.
To investigate the feasibility of a national audit of epistaxis management led and delivered by a multi-region trainee collaborative using a web-based interface to capture patient data.
Six trainee collaboratives across England nominated one site each and worked together to carry out this pilot. An encrypted data capture tool was adapted and installed within the infrastructure of a university secure server. Site-lead feedback was assessed through questionnaires.
Sixty-three patients with epistaxis were admitted over a two-week period. Site leads reported an average of 5 minutes to complete questionnaires and described the tool as easy to use. Data quality was high, with little missing data. Site-lead feedback showed high satisfaction ratings for the project (mean, 4.83 out of 5).
This pilot showed that trainee collaboratives can work together to deliver an audit using an encrypted data capture tool cost-effectively, whilst maintaining the highest levels of data quality.
(1) To systematically search for all dynamic mathematical models of infectious disease transmission in long-term care facilities (LTCFs); (2) to critically evaluate models of interventions against antimicrobial resistance (AMR) in this setting; and (3) to develop a checklist for hospital epidemiologists and policy makers by which to distinguish good quality models of AMR in LTCFs.
The CINAHL, EMBASE, Global Health, MEDLINE, and Scopus databases were systematically searched for studies of dynamic mathematical models set in LTCFs. Models of interventions targeting methicillin-resistant Staphylococcus aureus in LTCFs were critically assessed. Using this analysis, we developed a checklist for good quality mathematical models of AMR in LTCFs.
RESULTS AND DISCUSSION
Overall, 18 papers described mathematical models that characterized the spread of infectious diseases in LTCFs, but no models of AMR in gram-negative bacteria in this setting were described. Future models of AMR in LTCFs require a more robust methodology (ie, formal model fitting to data and validation), greater transparency regarding model assumptions, setting-specific data, realistic and current setting-specific parameters, and inclusion of movement dynamics between LTCFs and hospitals.
Mathematical models of AMR in gram-negative bacteria in the LTCF setting, where these bacteria are increasingly becoming prevalent, are needed to help guide infection prevention and control. Improvements are required to develop outputs of sufficient quality to help guide interventions and policy in the future. We suggest a checklist of criteria to be used as a practical guide to determine whether a model is robust enough to test policy.
Experiments on the National Ignition Facility show that multi-dimensional effects currently dominate the implosion performance. Low mode implosion symmetry and hydrodynamic instabilities seeded by capsule mounting features appear to be two key limiting factors for implosion performance. One reason these factors have a large impact on the performance of inertial confinement fusion implosions is the high convergence required to achieve high fusion gains. To tackle these problems, a predictable implosion platform is needed meaning experiments must trade-off high gain for performance. LANL has adopted three main approaches to develop a one-dimensional (1D) implosion platform where 1D means measured yield over the 1D clean calculation. A high adiabat, low convergence platform is being developed using beryllium capsules enabling larger case-to-capsule ratios to improve symmetry. The second approach is liquid fuel layers using wetted foam targets. With liquid fuel layers, the implosion convergence can be controlled via the initial vapor pressure set by the target fielding temperature. The last method is double shell targets. For double shells, the smaller inner shell houses the DT fuel and the convergence of this cavity is relatively small compared to hot spot ignition. However, double shell targets have a different set of trade-off versus advantages. Details for each of these approaches are described.
To measure the trends in traditional marine food intake and serum vitamin D levels in Alaska Native women of childbearing age (20–29 years old) from the 1960s to the present.
We measured a biomarker of traditional food intake, the δ15N value, and vitamin D level, as 25-hydroxycholecalciferol (25(OH)D3) concentration, in 100 serum samples from 20–29-year-old women archived in the Alaska Area Specimen Bank, selecting twenty-five per decade from the 1960s to the 1990s. We compared these with measurements of red-blood-cell δ15N values and serum 25(OH)D3 concentrations from 20–29-year-old women from the same region collected during the 2000s and 2010s in a Center for Alaska Native Health Research study.
The Yukon Kuskokwim Delta region of south-west Alaska.
Alaska Native women (n 319) aged 20–29 years at the time of specimen collection.
Intake of traditional marine foods, as measured by serum δ15N values, decreased significantly each decade from the 1960s through the 1990s, then remained constant from the 1990s through the present (F5,306=77·4, P<0·0001). Serum vitamin D concentrations also decreased from the 1960s to the present (F4,162=26·1, P<0·0001).
Consumption of traditional marine foods by young Alaska Native women dropped significantly between the 1960s and the 1990s and was associated with a significant decline in serum vitamin D concentrations. Studies are needed to evaluate the promotion of traditional marine foods and routine vitamin D supplementation during pregnancy for this population.
The yields of spring barley during a medium-term (7 years) compost and slurry addition experiment and the soil carbon (C) and nitrogen (N) contents, bacterial community structure, soil microbial biomass and soil respiration rates have been determined to assess the effects of repeated, and in some cases very large, organic amendments on soil and crop parameters. For compost, total additions were equivalent to up to 119 t C/ha and 1·7 t N/ha and for slurry they were 25 t C/ha and 0·35 t N/ha over 7 years, which represented very large additions compared to control soil C and N contents (69 t C/ha and 0·3 t N/ha in the 0–30 cm soil depth). There was an initial positive response to compost and slurry addition on barley yield, but over the experiment the yield differential between the amounts of compost addition declined, indicating that repeated addition of compost at a lower rate over several years had the same cumulative effect as a large single compost application. By the end of the experiment it was clear that the addition of compost and slurry increased soil C and N contents, especially towards the top of the soil profile, as well as soil respiration rates. However, the increases in soil C and N contents were not proportional to the amount of C and N added, suggesting either that: (i) a portion of the added C and N was more vulnerable to loss; (ii) that its addition rendered another C or N pool in the soil more susceptible to loss; or (iii) that the C inputs from additional crop productivity did not increase in line with the organic amendments. Soil microbial biomass was depressed at the highest rate of organic amendment, and whilst this may have been due to genuine toxic or inhibitory effects of large amounts of compost, it could also be due to the inaccuracy of the substrate-induced respiration approach used for determining soil biomass when there is a large supply of organic matter. At the highest compost addition, the bacterial community structure was significantly altered, suggesting that the amendments significantly altered soil community dynamics.
The present study examined a cascade model of age 4 and 5 contextual, parent, parenting, and child factors on symptoms of oppositional defiant disorder (ODD) at age 6 in a diverse community sample of 796 children. Contextual factors include socioeconomic status, family stress, and conflict; parent factors included parental depression; parenting factors included parental hostility, support, and scaffolding skills; child factors included child effortful control (EC), negative affect (NA), and sensory regulation. Direct effects of age 5 conflict, hostility, scaffolding, EC, and NA were found. Significant indirect, cascading effects on age 6 ODD symptom levels were noted for age 4 socioeconomic status via age 5 conflict and scaffolding skills; age 4 parental depression via age 5 child NA; age 4 parental hostility and support via age 5 EC; age 4 support via age 5 EC; and age 4 attachment via age 5 EC. Parenting contributed to EC, and the age 5 EC effects on subsequent ODD symptom levels were distinct from age 5 parental contributions. Scaffolding and ODD symptoms may have a reciprocal relationship. These results highlight the importance of using a multidomain model to examine factors associated with ODD symptoms early in the child's grammar school years.
Using both a theoretical and an empirical approach, we have investigated the frequency of low redshift galaxy-galaxy lensing systems in which the signature of 3D weak lensing might be directly detectable. We find good agreement between these two approaches. Using data from the Galaxy and Mass Assembly redshift survey we estimate the frequency of detectable weak lensing at low redshift. We find that below a redshift of z ~ 0.6, the probability of a galaxy being weakly lensed by γ ⩾ 0.02 is ~ 0.01. We have also investigated the feasibility of measuring the scatter in the M* − Mh relation using shear statistics. We estimate that for a shear measurement error of Δγ = 0.02 (consistent with the sensitivity of the Direct Shear Mapping technique), with a sample of ~$50,000 spatially and spectrally resolved galaxies, the scatter in the M* − Mh relation could be measured. While there are currently no existing IFU surveys of this size, there are upcoming surveys that will provide this data (e.g The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), surveys with Hector, and the Square Kilometre Array (SKA)).
The Evolutionary Map of the Universe (EMU) is a proposed radio continuum survey
of the Southern Hemisphere up to declination + 30°, with the Australian
Square Kilometre Array Pathfinder (ASKAP). EMU will use an automated source
identification and measurement approach that is demonstrably optimal, to
maximise the reliability and robustness of the resulting radio source
catalogues. As a step toward this goal we conducted a “Data
Challenge” to test a variety of source finders on simulated images. The
aim is to quantify the accuracy and limitations of existing automated source
finding and measurement approaches. The Challenge initiators also tested the
current ASKAPsoft source-finding tool to establish how it could benefit from
incorporating successful features of the other tools. As expected, most finders
show completeness around 100% at ≈ 10σ dropping to about 10% by
≈ 5σ. Reliability is typically close to 100% at ≈
10σ, with performance to lower sensitivities varying between finders. All
finders show the expected trade-off, where a high completeness at low
signal-to-noise gives a corresponding reduction in reliability, and vice versa.
We conclude with a series of recommendations for improving the performance of
the ASKAPsoft source-finding tool.
This study aimed to measure changes in disease-specific quality of life in children following tonsillectomy or adenotonsillectomy.
A multicentre prospective cohort study was performed involving seven ENT departments in England. A total of 276 children entered the study over a 2-month period: 107 underwent tonsillectomy and 128 adenotonsillectomy. Forty-one children referred with throat problems initially managed by watchful waiting were also recruited. The follow-up period was 12 months. Outcome measures were the T14, parental impressions of their child's quality of life and the number of days absent from school.
One-year follow-up data were obtained from 150 patients (52 per cent). The mean baseline T14 score in the non-surgical group was significantly lower (T14 = 23) than in the tonsillectomy group (T14 = 31) or the adenotonsillectomy group (T14 = 35; p < 0.001). There was a significant improvement in the T14 scores of responders in all groups at follow up. The effect size was 1.3 standard deviations (SD) for the non-surgical group, 2.1 SD for the tonsillectomy group and 1.9 SD for the adenotonsillectomy group. Between-group differences did not reach statistical significance. A third of children in the non-surgical group underwent surgery during the follow-up period.
Children who underwent surgical intervention achieved a significant improvement in disease-specific quality of life. Less severely affected children were managed conservatively and also improved over 12 months, but 1 in 3 crossed over to surgical intervention.