5,734 research outputs found

    Discouraged Immigrants and the Missing Pop in EPOP

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    We address the impact of declining migration on the measurement of labor market health. We first document an historically significant decline in the growth rate of the U.S. foreign born population since 2000. A decomposition shows that nearly two-thirds of the decline can be attributed to declining pull factors in the U.S. Had this decline not occurred, there would have been approximately 7.2 million more immigrants present in the U.S. in 2013. Making a conservative assumption about the hypothetical likelihood of employment for these "Discouraged Immigrants," a recalculation of the Employment to Population Ratio reveals a 13% larger decline since 2000 than is shown when conventionally measured

    A systematic review of local vulnerability to climate change: in search of transparency, coherence and comparability

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    Because vulnerability is a conceptual construct rather than a directly observable phenomenon, most vulnerability assessments measure a set of “vulnerability indicators”. In order to identify the core approaches and range of variation in the field, we conducted a systematic literature review on local vulnerability to climate change. The systematic review entailed an identification of frameworks, concepts, and operationalizations and a transparency assessment of their reporting. Three fully defined relevant frameworks of vulnerability were identified: IPCC, Patterns of Smallholder Vulnerability and Vulnerability as Expected Poverty. Comparative analysis found substantial heterogeneity in frameworks, concepts and operationalizations, making it impossible to identify patterns of climate vulnerability indicators and determinants that have robust empirical support. If research measuring farmers’ vulnerability to climate change is to have any comparability, it needs greater conceptual coherence and empirical validity. We recommend a systematic program of testing and validating vulnerability measures before institutionalizing them in programmatic contexts

    Functional trade-offs in cribellate silk mediated by spinning behavior

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    Web-building spiders are an extremely diverse predatory group due to their use of physiologically differentiated silk types in webs. Major shifts in silk functional properties are classically attributed to innovations in silk genes and protein expression. Here, we disentangle the effects of spinning behavior on silk performance of the earliest types of capture threads in spider webs for the first time. Progradungula otwayensis produces two variations of cribellate silk in webs: ladder lines are stereotypically combed with the calamistrum while supporting rail lines contain silk that is naturally uncombed, spun without the intervention of the legs. Combed cribellate silk is highly extensible and adhesive suggesting that the reserve warp and cribellate fibrils brings them into tension only near or after the underlying axial fibers are broken. In contrast, these three fiber components are largely aligned in the uncombed threads and deform as a single composite unit that is 5–10x stronger, but significantly less adhesive, allowing them to act as structural elements in the web. Our study reveals that cribellate silk can occupy a surprisingly diverse performance space, accessible through simple changes in spider behavior, which may have facilitated the impressive diversification of web architectures utilizing this ancient silk.Fil: Michalik, Peter. ERNST MORITZ ARNDT UNIVERSITÄT GREIFSWALD (UG);Fil: Piorkowski, Dakota. Tunghai University; ChinaFil: Blackledge, Todd A.. University of Akron; Estados UnidosFil: Ramirez, Martin Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin

    Temporal variation in macroalgal removal: insights from an impacted equatorial coral reef system

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    Macroalgal removal is a critical ecosystem function yet few studies have considered its temporal variability, especially on impacted reefs with limited herbivorous fish biodiversity. To address this, we quantified macroalgal removal and mass-standardised bite rates of herbivorous fishes monthly from July 2016 to June 2017 using a series of transplanted Sargassum ilicifolium assays and underwater video cameras on three degraded coral reefs in Singapore: Pulau Satumu, Kusu Island, and Terumbu Pempang Tengah. Our results revealed a distinct temporal pattern in macroalgal herbivory (proportion of biomass removed and mass-standardised bite rates) rates across all sites, increasing from July and decreasing from January, with the highest rates recorded in December (28.10 ± 3.05 g 3.5 h−1; 208.24 ± 29.99 mass-standardised bites 3.5 h−1) and the lowest in May (0.86 ± 0.17 g 3.5 h−1; 9.55 ± 3.19 mass-standardised bites 3.5 h−1). These coincided with the S. ilicifolium growth cycle, confirming previous evidence that herbivory rates are closely linked to macroalgal condition. Video analyses revealed nine species feeding over a year (31,839 bites; 8702.89 mass-standardised bites), with Siganus virgatus responsible for ∼ 80% of the total mass-standardised bites. Siganus virgatus took the largest proportion of bites monthly, except between April and June, when Scarus rivulatus was dominant, suggesting temporal constraints in functional roles

    AlphaFold predicts the most complex protein knot and composite protein knots

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    The computer artificial intelligence system AlphaFold has recently predicted previously unknown three-dimensional structures of thousands of proteins. Focusing on the subset with high-confidence scores, we algorithmically analyze these predictions for cases where the protein backbone exhibits rare topological complexity, i.e. knotting. Amongst others, we discovered a 717_1-knot, the most topologically complex knot ever found in a protein, as well several 6-crossing composite knots comprised of two methyltransferase or carbonic anhydrase domains, each containing a simple trefoil knot. These deeply embedded composite knots occur evidently by gene duplication and interconnection of knotted dimers. Finally, we report two new five-crossing knots including the first 515_1-knot. Our list of analyzed structures forms the basis for future experimental studies to confirm these novel knotted topologies and to explore their complex folding mechanisms.Comment: This article appeared openly accessible in M. A. Brems et al., Protein Science. 2022; 31( 8):e4380 and may be found at https://doi.org/10.1002/pro.438
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