We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
To save 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 saving content to .
To save content items to your Kindle, first ensure no-reply@cambridge.org
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 saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved 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.
This comprehensive text focuses on the homotopical technology in use at the forefront of modern algebraic topology. Following on from a standard introductory algebraic topology sequence, it will provide students with a comprehensive background in spectra and structured ring spectra. Each chapter is an extended tutorial by a leader in the field, offering the first really accessible treatment of the modern construction of the stable category in terms of both model categories of point-set diagram spectra and infinity-categories. It is one of the only textbook sources for operadic algebras, structured ring spectra, and Bousfield localization, which are now basic techniques in the field, and the book provides a rare expository treatment of spectral algebraic geometry. Together the contributors — Emily Riehl, Daniel Dugger, Clark Barwick, Michael A. Mandell, Birgit Richter, Tyler Lawson, and Charles Rezk — offer a complete, authoritative source to learn the foundations of this vibrant area.
The marketing of unhealthy foods has been implicated in poor diet and rising levels of obesity. Rapid developments in the digital food marketing ecosystem and associated research mean that contemporary review of the evidence is warranted. This preregistered (CRD420212337091)1 systematic review and meta-analysis aimed to provide an updated synthesis of the evidence for behavioural and health impacts of food marketing on both children and adults, using the 4Ps framework (Promotion, Product, Price, Place). Ten databases were searched from 2014 to 2021 for primary data articles of quantitative or mixed design, reporting on one or more outcome of interest following food marketing exposure compared with a relevant control. Reviews, abstracts, letters/editorials and qualitative studies were excluded. Eighty-two studies were included in the narrative review and twenty-three in the meta-analyses. Study quality (RoB2/Newcastle–Ottawa scale) was mixed. Studies examined ‘promotion’ (n 55), ‘product’ (n 17), ‘price’ (n 15) and ‘place’ (n 2) (some > 1 category). There is evidence of impacts of food marketing in multiple media and settings on outcomes, including increased purchase intention, purchase requests, purchase, preference, choice, and consumption in children and adults. Meta-analysis demonstrated a significant impact of food marketing on increased choice of unhealthy foods (OR = 2·45 (95 % CI 1·41, 4·27), Z = 3·18, P = 0·002, I2 = 93·1 %) and increased food consumption (standardised mean difference = 0·311 (95 % CI 0·185, 0·437), Z = 4·83, P < 0·001, I2 = 53·0 %). Evidence gaps were identified for the impact of brand-only and outdoor streetscape food marketing, and for data on the extent to which food marketing may contribute to health inequalities which, if available, would support UK and international public health policy development.
The cornerstone of obesity treatment is behavioural weight management, resulting in significant improvements in cardio-metabolic and psychosocial health. However, there is ongoing concern that dietary interventions used for weight management may precipitate the development of eating disorders. Systematic reviews demonstrate that, while for most participants medically supervised obesity treatment improves risk scores related to eating disorders, a subset of people who undergo obesity treatment may have poor outcomes for eating disorders. This review summarises the background and rationale for the formation of the Eating Disorders In weight-related Therapy (EDIT) Collaboration. The EDIT Collaboration will explore the complex risk factor interactions that precede changes to eating disorder risk following weight management. In this review, we also outline the programme of work and design of studies for the EDIT Collaboration, including expected knowledge gains. The EDIT studies explore risk factors and the interactions between them using individual-level data from international weight management trials. Combining all available data on eating disorder risk from weight management trials will allow sufficient sample size to interrogate our hypothesis: that individuals undertaking weight management interventions will vary in their eating disorder risk profile, on the basis of personal characteristics and intervention strategies available to them. The collaboration includes the integration of health consumers in project development and translation. An important knowledge gain from this project is a comprehensive understanding of the impact of weight management interventions on eating disorder risk.
Hercules Dome, Antarctica, has long been identified as a prospective deep ice core site due to the undisturbed internal layering, climatic setting and potential to obtain proxy records from the Last Interglacial (LIG) period when the West Antarctic ice sheet may have collapsed. We performed a geophysical survey using multiple ice-penetrating radar systems to identify potential locations for a deep ice core at Hercules Dome. The surface topography, as revealed with recent satellite observations, is more complex than previously recognized. The most prominent dome, which we term ‘West Dome’, is the most promising region for a deep ice core for the following reasons: (1) bed-conformal radar reflections indicate minimal layer disturbance and extend to within tens of meters of the ice bottom; (2) the bed is likely frozen, as evidenced by both the shape of the measured vertical ice velocity profiles beneath the divide and modeled ice temperature using three remotely sensed estimates of geothermal flux and (3) models of layer thinning have 132 ka old ice at 45–90 m above the bed with an annual layer thickness of ~1 mm, satisfying the resolution and preservation needed for detailed analysis of the LIG period.
The modern era in homotopy theory began in the 1960s with the profound realization, first codified by Boardman in his construction of the stable category, that the category of spaces up to stable homotopy equivalence is equipped with a rich algebraic structure, formally similar to the derived category of a commutative ring R. For example, for pointed spaces the natural map from the categorical coproduct to the categorical product becomes more and more connected as the pieces themselves become more and more connected. In the limit, this map becomes a stable equivalence, just as finitely indexed direct sums and direct products coincide for R-modules.
From this perspective, the objects of the stable category are modules over an initial commutative ring object that replaces the integers: the sphere spectrum. However, technical difficulties immediately arose. Whereas the tensor product of R-modules is an easy and familiar construction, the analogous construction of a symmetric monoidal smash product on spectra seemed to involve a huge number of ad hoc choices [1]. As a consequence, the smash product was associative and commutative only up to homotopy. The lack of a good point-set symmetric monoidal product on spectra precluded making full use of the constructions from commutative algebra in this setting — even just defining good categories of modules over a commutative ring spectrum was difficult. In many ways, finding ways to rectify this and to make the guiding metaphor provided by “modules over the sphere spectrum” precise has shaped the last 60 years of homotopy theory.
This book arose from a desire by the editors to have a reference to give to their students who have taken a standard algebraic topology sequence and who want to learn about spectra and structured ring spectra. While there are many excellent texts which introduce students to the basic ideas of homotopy theory and to spectra, there has not been a place for students to engage directly with the ideas needed to connect with commutative ring spectra and work with these objects. This book strives to provide an introduction to this whole circle of ideas, describing the tools that homotopy theorists have developed to build, explore, and use symmetric monoidal categories of spectra that refine the stable homotopy category:
1. model category structures on symmetric monoidal categories of spectra,
2. stable ∞-categories, and
3. operads and operadic algebras.
These three concepts are closely intertwined, and they all engage deeply with a fundamental principle: if the choices for some construction or map are parameterized by a space, then recording that space as part of the data makes the construction more natural.
Major depressive disorder and neuroticism (Neu) share a large genetic basis. We sought to determine whether this shared basis could be decomposed to identify genetic factors that are specific to depression.
Methods
We analysed summary statistics from genome-wide association studies (GWAS) of depression (from the Psychiatric Genomics Consortium, 23andMe and UK Biobank) and compared them with GWAS of Neu (from UK Biobank). First, we used a pairwise GWAS analysis to classify variants as associated with only depression, with only Neu or with both. Second, we estimated partial genetic correlations to test whether the depression's genetic link with other phenotypes was explained by shared overlap with Neu.
Results
We found evidence that most genomic regions (25/37) associated with depression are likely to be shared with Neu. The overlapping common genetic variance of depression and Neu was genetically correlated primarily with psychiatric disorders. We found that the genetic contributions to depression, that were not shared with Neu, were positively correlated with metabolic phenotypes and cardiovascular disease, and negatively correlated with the personality trait conscientiousness. After removing shared genetic overlap with Neu, depression still had a specific association with schizophrenia, bipolar disorder, coronary artery disease and age of first birth. Independent of depression, Neu had specific genetic correlates in ulcerative colitis, pubertal growth, anorexia and education.
Conclusion
Our findings demonstrate that, while genetic risk factors for depression are largely shared with Neu, there are also non-Neu-related features of depression that may be useful for further patient or phenotypic stratification.
X-ray laboratory diffraction contrast tomography (LabDCT) produces three-dimensional (3D) maps of crystallographic orientation. The non-destructive nature of the technique affords the key benefit of full 3D context of these, and other, in situ measurements. This study is the first to apply the technique to any material other than a metal or silicon. We report the first 3D measurements of the crystallographic orientation of olivine, which also makes this study the first to apply LabDCT to (1) a non-metallic, non-cubic system and (2) geological material. First, we scanned fragments of olivine set in resin alongside glass microbeads using LabDCT and absorption contrast tomography (ACT). Then we reconstructed these data assuming an orthorhombic crystal system. We show that: (1) the regions within the sample that index well according to the orthorhombic system correspond to olivine fragments in the ACT image; (2) crystalline regions not corresponding to olivine are not indexed assuming the same lattice parameters; and (3) the diffraction data discriminates crystalline from non-crystalline materials as expected. Finally, we demonstrate that the method resolves sub-degree orientation differences between distinct regions within individual olivine fragments. We conclude that DCT can be applied to the study of rocks and other crystalline materials, and offers advantages over conventional techniques. We also note that LabDCT may offer a solution to the crystallographic measurement of substances that would otherwise be difficult to measure due to challenges in obtaining a perfect sample polish. Future developments to accommodate larger experimental volumes and additional crystallographic systems within a sample promises to expand the applicability and impact of DCT.
To assess the effect of rural-to-urban migration on nutrition transition and overweight/obesity risk among women in Kenya.
Design:
Secondary analysis of data from nationally representative cross-sectional samples. Outcome variables were women’s BMI and nutrition transition. Nutrition transition was based on fifteen different household food groups and was adjusted for socio-economic and demographic characteristics. Stepwise backward multiple ordinal regression analysis was applied.
Setting:
Kenya Demographic and Health Survey 2014.
Participants:
Rural non-migrant, rural-to-urban migrant and urban non-migrant women aged 15–49 years (n 6171).
Results:
Crude data analysis showed rural-to-urban migration to be associated with overweight/obesity risk and nutrition transition. After adjustment for household wealth, no significant differences between rural non-migrants and rural-to-urban migrants for overweight/obesity risk and household consumption of several food groups characteristic of nutrition transition (animal-source, fats and sweets) were observed. Regardless of wealth, migrants were less likely to consume main staples and legumes, and more likely to consume fruits and vegetables. Identified predictive factors of overweight/obesity among migrant women were age, duration of residence in urban area, marital status and household wealth.
Conclusions:
Our analysis showed that nutrition transition and overweight/obesity risk among rural-to-urban migrants is apparent with increasing wealth in urban areas. Several predictive factors were identified characterising migrant women being at risk for overweight/obesity. Future research is needed which investigates in depth the association between rural-to-urban migration and wealth to address inequalities in diet and overweight/obesity in Kenya.
The ventricular assist device is being increasingly used as a “bridge-to-transplant” option in children with heart failure who have failed medical management. Care for this medically complex population must be optimised, including through concomitant pharmacotherapy. Pharmacokinetic/pharmacodynamic alterations affecting pharmacotherapy are increasingly discovered in children supported with extracorporeal membrane oxygenation, another form of mechanical circulatory support. Similarities between extracorporeal membrane oxygenation and ventricular assist devices support the hypothesis that similar alterations may exist in ventricular assist device-supported patients. We conducted a literature review to assess the current data available on pharmacokinetics/pharmacodynamics in children with ventricular assist devices. We found two adult and no paediatric pharmacokinetic/pharmacodynamic studies in ventricular assist device-supported patients. While mechanisms may be partially extrapolated from children supported with extracorporeal membrane oxygenation, dedicated investigation of the paediatric ventricular assist device population is crucial given the inherent differences between the two forms of mechanical circulatory support, and pathophysiology that is unique to these patients. Commonly used drugs such as anticoagulants and antibiotics have narrow therapeutic windows with devastating consequences if under-dosed or over-dosed. Clinical studies are urgently needed to improve outcomes and maximise the potential of ventricular assist devices in this vulnerable population.
Accuracy of intracranial magnetic resonance angiography (MRA) and reliability of interpretation are not well established compared to conventional selective catheter angiography. The purpose of this study was to determine the accuracy of MRA in evaluation of intracranial vessels in acute stroke and transient ischemic attack (TIA) patients.
Methods:
Twenty-nine patients (seven females, 22 males; median age 53) with acute stroke or TIA were enrolled into the study. All patients underwent both MRA using a 3 T clinical magnet and conventional angiography within 48 hours. Median time between MRA and angiography was 263 minutes. Conventional angiography preceded MRA in 15 cases. Fourteen patients received thrombolysis during MRA or angiography. National Institutes of Health Stroke Scale scores were obtained prior to the MR exam. One neuroradiologist rated all conventional angiograms, which were used as gold standard. Five observers, blinded to conventional angiography results and all clinical information except symptom side, rated the MR angiograms. Kappa statistics were used to assess reliability; contingency tables were used to assess accuracy of non-enhanced and enhanced MRA.
Results:
Two hundred and fifty two intracranial vessels were assessed. Agreement between raters was good for both non-enhanced (k=0.50) and gadolinium-enhanced (k=0.46) images. There were a total of 26 vessels occluded by DSA. Overall, the non-enhanced MRA showed sensitivity of 84.2% (95% CI 60.4-96.6) and specificity of 84.6% (95% CI 78.6-89.4). The enhanced MRA showed sensitivity of 69.2 (95% CI 38.6-90.9) and specificity of 73.6 (95% CI 65.5-80.7).
Conclusions:
Magnetic resonance angiography is a good non-invasive screening tool for assessing intracranial vessel status in acute ischemic stroke. Angiography remains the gold standard for definitive assessment of the intracranial circulation.
Emergency Medical Services (EMS) providers face many ethical issues while providing prehospital care to children and adults. Although provider judgment plays a large role in the resolution of conflicts at the scene, it is important to establish protocols and policies, when possible, to address these high-risk and complex situations. This article describes some of the common situations with ethical underpinnings encountered by EMS personnel and managers including denying or delaying transport of patients with non-emergency conditions, use of lights and sirens for patient transport, determination of medical futility in the field, termination of resuscitation, restriction of EMS provider duty hours to prevent fatigue, substance abuse by EMS providers, disaster triage and difficulty in switching from individual care to mass-casualty care, and the challenges of child maltreatment recognition and reporting. A series of ethical questions are proposed, followed by a review of the literature and, when possible, recommendations for management.
BeckerTK, Gausche-HillM, AsweganAL, BakerEF, BookmanKJ, BradleyRN, De LorenzoRA, SchoenwetterDJ for the American College of Emergency Physicians’ EMS Committee. Ethical Challenges in Emergency Medical Services: Controversies and Recommendations. Prehosp Disaster Med. 2013;28(5):1-10.