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 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 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.
Female fertility is a complex trait with age-specific changes in spontaneous dizygotic (DZ) twinning and fertility. To elucidate factors regulating female fertility and infertility, we conducted a genome-wide association study (GWAS) on mothers of spontaneous DZ twins (MoDZT) versus controls (3273 cases, 24,009 controls). This is a follow-up study to the Australia/New Zealand (ANZ) component of that previously reported (Mbarek et al., 2016), with a sample size almost twice that of the entire discovery sample meta-analysed in the previous article (and five times the ANZ contribution to that), resulting from newly available additional genotyping and representing a significant increase in power. We compare analyses with and without male controls and show unequivocally that it is better to include male controls who have been screened for recent family history, than to use only female controls. Results from the SNP based GWAS identified four genomewide significant signals, including one novel region, ZFPM1 (Zinc Finger Protein, FOG Family Member 1), on chromosome 16. Previous signals near FSHB (Follicle Stimulating Hormone beta subunit) and SMAD3 (SMAD Family Member 3) were also replicated (Mbarek et al., 2016). We also ran the GWAS with a dominance model that identified a further locus ADRB2 on chr 5. These results have been contributed to the International Twinning Genetics Consortium for inclusion in the next GWAS meta-analysis (Mbarek et al., in press).
Biological invasions are a threat to protected areas globally; however, the relative lack of studies quantifying the ecological impacts impairs informed decision-making. We selected three annual alien plants, widespread in the riparian habitats of the Kruger National Park, South Africa: Datura innoxia, Parthenium hysterophorus, and Xanthium strumarium, to examine their potential impacts on riparian plant communities. We identified 12–13 populations for each and placed a pair of invaded and uninvaded plots in each population. Species richness, Shannon diversity, and Pielou evenness were compared between the invaded and uninvaded plots using LMM models, and species composition was compared using ordination. The invaded vegetation showed lower species richness compared to the uninvaded, with the strongest effect observed for P. hysterophorus. The invaded plots also showed lower Shannon diversity and Pielou evenness due to the presence of alien dominants. For all three invaders, the invasion resulted in changes in the composition of native vegetation. Some native plants were more frequent and abundant in the invaded vegetation, possibly due to the habitats created in sandy river beds. The native species richness decreased with increasing invader cover, but the species richness of aliens accompanying the invasive dominants was not negatively affected by their cover. Our results confirmed the negative impact of invasive aliens on native plant diversity, with the most pronounced effect by Parthenium hysterophorus invasions.
Following Afghanistan’s fall in August 2021, many refugees were settled in the United States as part of Operation Allies Welcome. They were flown from Kabul to the Middle East and Europe before continuing to the U.S. By late September Philadelphia was the sole destination. From there refugees were transported to Safe Haven military bases around the country. Philadelphia International Airport became the site of a months-long operation involving city, state, federal, and private agencies engaged in processing, medical screening, and COVID-testing of arriving refugees. The Philadelphia Fire Department played an integral role. Minor medical conditions were treated onsite. Higher acuity patients were transported to nearby hospitals. The goal was to maintain flow of refugees to their next destination while addressing acute medical issues. Between August 28, 2021, and March 1, 2022, the airport processed 29,713 refugees. Philadelphia’s experience may serve as a guide for planning future such refugee operations.
There is a dearth of data on Se status in very old adults. The aims of this study were to assess Se status and its determinants in 85-year-olds living in the Northeast of England by measuring serum Se and selenoprotein P (SELENOP) concentrations and glutathione peroxidase 3 (GPx3) activity. A secondary aim was to examine the interrelationships between each of the biomarkers. In total, 757 participants (463 women, 293 men) from the Newcastle 85+ Study were included. Biomarker concentrations were compared with selected cut-offs (serum Se: suboptimal 70 µg/l and deficient 45 µg/l; SELENOP: suboptimal 4·5 mg/l and deficient 2·6 mg/l). Determinants were assessed using linear regressions, and interrelationships were assessed using restricted cubic splines. Median (inter-quartile range) concentrations of serum Se, SELENOP and of GPx3 activity were 53·6 (23·6) µg/l, 2·9 (1·9) mg/l and 142·1 (50·7) U/l, respectively. Eighty-two percentage and 83 % of participants had suboptimal serum Se (< 70 µg/l) and SELENOP (< 4·5 mg/l), and 31 % and 40 % of participants had deficient serum Se (< 45 µg/l) and SELENOP (< 2·6 mg/l), respectively. Protein intake was a significant determinant of Se status. Additional determinants of serum Se were sex, waist:hip ratio, self-rated health and disease, while sex, BMI and physical activity were determinants of GPx3 activity. There was a linear association between serum Se and SELENOP, and nonlinear associations between serum Se and GPx3 activity and between SELENOP and GPx3 activity. These findings indicate that most participants had suboptimal Se status to saturate circulating SELENOP.
In this paper, we study triple-product-free sets, which are analogous to the widely studied concept of product-free sets. A nonempty subset S of a group G is triple-product-free if $abc \notin S$ for all $a, b, c \in S$. If S is triple-product-free and is not a proper subset of any other triple-product-free set, we say that S is locally maximal. We classify all groups containing a locally maximal triple-product-free set of size 1. We then derive necessary and sufficient conditions for a subset of a group to be locally maximal triple-product-free, and conclude with some observations and comparisons with the situation for standard product-free sets.
The distribution of avian haemosporidians of the genus Leucocytozoon in the Neotropics remains poorly understood. Recent studies confirmed their presence in the region using molecular techniques alone, but evidence for gametocytes and data on putative competent hosts for Leucocytozoon are still lacking outside highland areas. We combined morphological and molecular data to characterize a new Leucocytozoon species infecting a non-migratory red-legged seriema (Cariama cristata), the first report of a competent host for Leucocytozoon in Brazil. Leucocytozoon cariamae n. sp. is distinguished from the Leucocytozoon fringillinarum group by its microgametocytes that are not strongly appressed to the host cell nucleus. The bird studied was coinfected with Haemoproteus pulcher, and we present a Bayesian phylogenetic analysis based on nearly complete mitochondrial genomes of these 2 parasites. Leucocytozoon cariamae n. sp. morphology is consistent with our phylogenetic analysis indicating that it does not share a recent common ancestor with the L. fringillinarum group. Haemoproteus pulcher and Haemoproteus catharti form a monophyletic group with Haemocystidium parasites of Reptilia, supporting the polyphyly of the genus Haemoproteus. We also discussed the hypothesis that H. pulcher and H. catharti may be avian Haemocystidium, highlighting the need to study non-passerine parasites to untangle the systematics of Haemosporida.
US regulations mandate annual N95 mask fit testing for healthcare workers, but the optimal testing interval is unknown. In our study using data from 12,565 healthcare workers, the probability of survival free from fit-test failure after 3 years was 99.4%, suggesting that less frequent fit testing every 3 years would be safe.
The U.S. Department of Agriculture–Agricultural Research Service (USDA-ARS) has been a leader in weed science research covering topics ranging from the development and use of integrated weed management (IWM) tactics to basic mechanistic studies, including biotic resistance of desirable plant communities and herbicide resistance. ARS weed scientists have worked in agricultural and natural ecosystems, including agronomic and horticultural crops, pastures, forests, wild lands, aquatic habitats, wetlands, and riparian areas. Through strong partnerships with academia, state agencies, private industry, and numerous federal programs, ARS weed scientists have made contributions to discoveries in the newest fields of robotics and genetics, as well as the traditional and fundamental subjects of weed–crop competition and physiology and integration of weed control tactics and practices. Weed science at ARS is often overshadowed by other research topics; thus, few are aware of the long history of ARS weed science and its important contributions. This review is the result of a symposium held at the Weed Science Society of America’s 62nd Annual Meeting in 2022 that included 10 separate presentations in a virtual Weed Science Webinar Series. The overarching themes of management tactics (IWM, biological control, and automation), basic mechanisms (competition, invasive plant genetics, and herbicide resistance), and ecosystem impacts (invasive plant spread, climate change, conservation, and restoration) represent core ARS weed science research that is dynamic and efficacious and has been a significant component of the agency’s national and international efforts. This review highlights current studies and future directions that exemplify the science and collaborative relationships both within and outside ARS. Given the constraints of weeds and invasive plants on all aspects of food, feed, and fiber systems, there is an acknowledged need to face new challenges, including agriculture and natural resources sustainability, economic resilience and reliability, and societal health and well-being.
Bacterial antimicrobial resistance (AMR) is among the leading global health challenges of the century. Animals and their products are known contributors to the human AMR burden, but the extent of this contribution is not clear. This systematic literature review aimed to identify studies investigating the direct impact of animal sources, defined as livestock, aquaculture, pets, and animal-based food, on human AMR. We searched four scientific databases and identified 31 relevant publications, including 12 risk assessments, 16 source attribution studies, and three other studies. Most studies were published between 2012 and 2022, and most came from Europe and North America, but we also identified five articles from South and South-East Asia. The studies differed in their methodologies, conceptual approaches (bottom-up, top-down, and complex), definitions of the AMR hazard and outcome, the number and type of sources they addressed, and the outcome measures they reported. The most frequently addressed animal source was chicken, followed by cattle and pigs. Most studies investigated bacteria–resistance combinations. Overall, studies on the direct contribution of animal sources of AMR are rare but increasing. More recent publications tailor their methodologies increasingly towards the AMR hazard as a whole, providing grounds for future research to build on.
In Part I we examined the form and function ofthe major families of power electronic converters.Our goal was to show how the intended powerconversion function is achieved in each case byappropriate configuration of the circuitcomponents and by proper operation of theswitches. Throughout those earlier chapters, ourconcern was with nominal operating conditions, that is,the ideal operating conditions in which aconverter is designed to perform its primaryconversion function. As nominal operation in mostpower electronic circuits involves a periodic steady state, wefocused on situations in which circuit operationand behavior are the same from cycle to cycle.
Power magnetics are often constrained by loss.Consequently, the ability to accurately predictthe loss of a magnetic component is extremelyvaluable for design. The techniques for modelingmagnetics loss introduced in the previous chaptersare useful, but do not adequately cover allsituations. In this chapter we introduce refinedmethods to predict winding and core losses inmagnetic components, with particular emphasis onfactors (such as proximity effect) that becomedominant at high frequencies and on cases wherethe waveforms are not purely dc or sinusoidal.
We add transformers to the topology of ahigh-frequency converter for three reasons: toprovide electrical isolation between two (or more)external systems; to reduce the component stressesthat result when the input/output conversion ratiois far from unity; and to create multiple relatedoutputs in a simple manner. (We showed therelationship between switch-stress factor and theconversion ratio in Fig. 5.26.) There are manyways in which we can include the transformer inthe topology of a dc/dc converter; we present anddiscuss some of them in this chapter.
Power electronic circuits change the characterof electrical energy: from dc or ac to ac or dc,from one voltage level or frequency to another, orin some other way. We refer to such circuitsgenerically as converters, staticconverters (because they contain nomoving parts), powerprocessors, or powerconditioners. The part of the system thatactually manipulates the flow of energy is thepower circuit. It isthe scaffold for the system’s other components,such as the control circuit or the thermalmanagement parts.
Substantially expanded and updated, the new edition of this classic textbook provides unrivalled coverage of the fundamentals of power electronics. Comprehensive coverage of foundational concepts in circuits, magnetics, devices, dynamic models, and control establishes a strong conceptual framework for further study. Extensive discussion of contemporary practical considerations, enhanced by real-world examples, prepares readers for design scenarios ranging from low-power dc/dc converters to multi-megawatt ac machine drives. New topics include SiC and GaN wide-bandgap materials, superjunction MOSFET and IGBT devices, advanced magnetics design, multi-level and switched-capacitor converters, RF converter circuits, and EMI. Over 300 new and revised end-of-chapter problems enhance and expand understanding of the material, with solutions for instructors. Unique in its breadth and depth, and providing a range of flexible teaching pathways at multiple levels, this is the definitive guide to power electronics for graduate and senior undergraduate students in electrical engineering, and practicing electrical engineers.
The rapid switching transitions of a powerconverter are potential sources of electromagneticinterference (EMI), both for the converter itselfand for the systems to which it is connected.Adequate filtering at the input and output of theconverter is important, both to obtain acceptableperformance and to prevent interference with otherequipment. In this chapter, we consider thesources of EMI in a converter, how EMI is measuredand modeled, and how it can be mitigated, with afocus on conducted (rather than radiated) EMI.