bluuebunny/crossref_metadata_2025 huggingface dataset:
Density Dependence, Hatching Synchrony, and within‐Cohort Cannibalism in Young Dragonfly Larvae
Authors: Hopper Kevin R. , Crowley Philip H. , Kielman Donna
Published: May 2006

We present two laboratory experiments designed to show how cannibalism and its effects on population numbers and size structure vary in response to density, size, and food manipulations in larvae of the dragonfly Epitheca cynosura. Because young larvae of this species interact at very high densities after hatching asynchronously from clumps of egg masses, our efforts focused on these early stages. In one experiment, we varied the combination of sizes (instars) and the presence of food for 233 pairs of early—instar larvae. Cannibalism was uncommon if larvae were of the same instar (only 2.4% of such pairs exhibited cannibalism), frequent (53%) if larvae differed by one instar, and certain (100%) if a two—instar size difference was present. The rate at which cannibalism increased with size differences between larvae was greater when food was absent than it was when food was provided. In a second experiment, we subjected replicate cohorts of newly hatched dragonflies to manipulations of hatching synchrony, initial density, and food availability. Asynchronous hatching over 25 d produced a broad size distribution apparently conducive to cannibalism, whereas synchronous hatching over 3 d initially precluded cannibalism. As a result, strong density—dependent mortality only appeared following the asynchronous hatch. For high—density, asynchronous treatments, cannibalism significantly reduced size variation and tightened size distributions over the course of development. Survivors from high—density treatments were significantly larger than were low—density survivors. More abundant food allowed larvae to reach larger sizes, but did not improve survival. Survival was affected mainly by the density and size distribution of larvae. These results suggest that cannibalism was more important than exploitative competition for food in determining the size and survival of dragonflies in the laboratory. We conclude that when juveniles hatch asynchronously in close proximity, cannibalism can: (1) contribute to population regulation by imposing greater per capita mortality at high densities, and (2) increase population synchrony by exerting size—specific mortality on smaller individuals throughout development.
Theory for Biological Control: Recent Developments
Authors: Murdoch William W. , Briggs Cheryl J.
Published: May 2006

It has been argued that ecological theory has not been useful to the practice of biological control. The purpose of this article is to show how recent theoretical advances may reverse this situation. We first discuss four issues that have arisen in the development of theory for biological control. (1) Recent work has clarified and resolved earlier disagreements concerning the effect of aggregation of the parasitoid to local host density on the stability of parasitoid—host models; this work emphasizes that such aggregation increases the ability of the parasitoid to reduce pest density. (2) There has been disagreement over the conditions under which stability, in the mathematical sense and on a local spatial scale, is an appropriate goal for classical biological control of insect pests, and whether a metapopulation may sometimes provide a more appropriate framework. We also comment on (3) relative size of refuges, which has been proposed as a unifying concept, and (4) density dependence and ratio dependence. We then discuss recent models using a stage—structured approach, particularly those that compare potential biological control agents or agents that have been differentially successful in practice. We argue that this approach has already produced valuable insights into the factors operating in several field situations. It demonstrates the importance of identifying which pest stages are most injurious to the crop, since the natural enemy that wins in competition may not be the most effective at suppressing the crucial pest stage(s): in general, the winning parasitoid reduces the density of the host stage attacked by its competitor below the level at which the latter can maintain a positive growth rate when at low density. A useful criterion is that pest equilibrium density is suppressed most by the parasitoid species that needs the fewest host individuals to allow a female parasitoid to replace herself in the next generation. Caveats are that this may apply only under equilibrium conditions and that the pest stage most suppressed is the one we wish to control. We discuss the connection between successful biological control and evolutionary considerations.
Competition and Facilitation: Contrasting Effects of Artemisia Tridentata on Desert vs. Montane Pines
Authors: Callaway Ragan M. , DeLucia Evan H. , Moore Darrin , Nowak Robert , Schlesinger William H.
Published: May 2006

Circumstantial evidence suggests that Artemisia tridentata may out—compete Pinus ponderosa and P. jefferyi for water at ecotones between shrub steppe and montane forest vegetation in the Great Basin. Other studies indicate that within the shrub steppe Artemisia may act as a nurse plant for a third species of pine, P. monophylla. We used field experiments to study these contrasting effects of Artemisia on P. ponderosa and P. monophylla within the context of the distributional patterns in western Nevada of all three species on andesite, and on sites where hydrothermal activity has altered the andesite. At intermediate elevations in the Great Basin Artemisia and P. monophylla are restricted to unaltered desert soils, whereas P. ponderosa is restricted to acidic, nutrient—poor altered andesite. Although mature P. monophylla were virtually absent in our study plots on altered andesite, first— and second—year seedlings were common. On adjacent unaltered andesite, all size classes of P. monophylla occurred, and P. monophylla seedlings were associated with Artemisia shrubs. Pinus ponderosa and P. jefferyi adults and seedlings were rare on unaltered andesite, but a wide range of size classes was found on altered andesite. In experiments, all P. ponderosa seedlings on unaltered andesite were consumed by predators regardless of positive or negative spatial association with shrubs. Of the P. monophylla seedlings that germinated on unaltered andesite, all that were under shrubs survived, but only 6% of those that germinated in the intershrub spaces survived. On the open altered andesite the mortality of P. monophylla seedlings due to abiotic stress was high, with a final survival of only 3%, whereas 28% of P. ponderosa seedlings survived the first growing season on altered andesite. On unaltered andesite, survival and conductance of P. ponderosa saplings was enhanced by shrub removal, but P. monophylla survival was significantly higher under shrubs than in shrub—removal plots or in intershrub spaces. In Artemisia—removal experiments, we found that Artemisia competed with P. ponderosa seedlings and saplings for water. Removal of Artemisia decreased water use efficiency (WUE) of P. monophylla seedlings. The absence of Artemisia may restrict Pinus monophylla from outcrops of altered andesite in the Great Basin, but provide refuges for P. ponderosa.
Channel Narrowing and Vegetation Development Following a Great Plains Flood
Authors: Friedman Jonathan M. , Osterkamp W. R. , Lewis William M.
Published: May 2006

Streams in the plains of eastern Colorado are prone to intense floods following summer thunderstorms. Here, and in other semiarid and arid regions, channel recovery after a flood may take several decades. As a result, flood history strongly influences spatial and temporal variability in bottomland vegetation. Interpretation of these patterns must be based on understanding the long—term response of bottomland morphology and vegetation to specific floods. A major flood in 1965 on Plum Creek, a perennial sandbed stream, removed most of the bottomland vegetation and transformed the single—thread stream into a wider, braided channel. Channel narrowing began in 1973 and continues today. In 1991, we determined occurrences of 150 vascular plant species in 341 plots (0.5 m2) along a 7—km reach of Plum Creek near Louviers, Colorado. We related patterns of vegetation to elevation, litter cover, vegetative cover, sediment particle size, shade, and year of formation of the underlying surface (based on age of the excavated root flare of the oldest woody plants). Geomorphic investigation determined that Plum Creek fluvial surfaces sort into five groups by year of formation: terraces of fine sand formed before 1965; terraces of coarse sand deposited by the 1965 flood; stable bars formed by channel narrowing during periods of relatively high bed level (1973—1986); stable bars similarly formed during a recent period of low bed level (1987—1990); and the present channel bed (1991). Canonical correspondence analysis indicates a strong influence of elevation and litter cover, and lesser effects of vegetative cover, shade, and sediment particle size. However, the sum of all canonical eigenvalues explained by these factors is less than that explained by an analysis including only the dummy variables that define the five geomorphically determined age groups. The effect of age group is significant even when all five other environmental variables are specified as covariables. Therefore, the process of postflood channel narrowing has a dominant influence on vegetation pattern. Channel narrowing at Plum Creek includes a successional process: annual and perennial plants become established on the channel bed, sediment accretes around the vegetation, and increasing litter cover, shade, and scarcity of water eliminate species that are not rhizomatous perennials. However, successional trajectories of individual surfaces are modified by flow—related fluctuations of the bed level; surfaces deposited by the 1965 flood have had distinct sediment and vegetation since their formation. Species richness is highest on surfaces dating to 1987—1990; the many species restricted to this transitory assemblage are perpetuated by flood—related fluctuations in channel width. Since the 1965 flood, seedling establishment of the dominant trees (genus Populus) has occurred only on low surfaces formed during channel narrowing. Thus, the flood has indirectly promoted Populus establishment over a 26—yr period.
Watercress Allelochemical Defends High‐Nitrogen Foliage Against Consumption: Effects on Freshwater Invertebrate Herbivores
Authors: Newman Raymond M. , Kerfoot W. Charles , Hanscom Zac
Published: May 2006

Watercress (Nasturtium officinale) is a spring—stream macrophyte that possesses glucosinolates, which are hydrolyzed to feeding deterrent isothiocyanates when the enzyme myrosinase is released by tissue damage. Previous studies indicated that frequently associated aquatic shredders strongly prefer yellowed—senescent leaves over fresh—green foliage, because the latter releases much more isothiocyanate than senescent watercress. When the action of myrosinase was blocked by heating the tissue, the shredders' preference shifted to heated—green tissue, which contains much more nitrogen than that found in senescent tissue. Here we report a series of no—choice experiments on various tissue types designed to determine intermediate and long—term consumption rates and associated impacts on growth and survival of shredders associated with watercress. The amphipod Gammarus pseudolimnaeus, the caddisflies Pycnopsyche sp., Hesperophylax designatus, and Limnephilus sp., and the snail Physella gyrina, all consumed much more senescent than fresh—green tissue. In long—term tests with G. pseudolimnaeus, H. designatus, and Limnephilus sp., growth was negative or zero on the defended fresh—green tissue and often highest on heated—green tissue. Reaction to glucosinolates differed among shredders. For the caddisflies, growth and survival were positively correlated with bulk tissue and nitrogen consumption, which were highest for heated—green tissue. However, amphipod survival was significantly lowered on heated—green watercress, although it was readily consumed. Therefore, consumption of high—glucosinolate tissue was detrimental to the amphipods but not to caddisflies. Our results indicate that the glucosinolate—myrosinase system defends live green watercress against herbivory by an array of aquatic invertebrates. These generalist herbivores forgo eating high—quality fresh—green leaves because of plant defenses and instead settle for lower quality senescent leaves. When the defense system was experimentally shut down, these herbivores readily consumed young green tissue and frequently showed higher growth rates than those achieved on the senescent, but undefended, leaves they typically consume. Evidently, these shredders face a trade—off of high nitrogen and high defense vs. low nitrogen and low defense.
Linking Herbivory and Pollination: Defoliation and Selective Fruit Abortion in Lindera Benzoin
Authors: Niesenbaum Richard A.
Published: May 2006

It has been predicted that plants will selectively mature fruit from flowers in which there has been the most intense pollen tube competition. The degree of this selectivity should increase as resources become more constrained and fruit abortion rates increase. One way in which resources could become more constrained is through defoliation by herbivores. The effect of defoliation on selective fruit abortion was tested by examining fruit set and pollen tube numbers in naturally pollinated flowers on defoliated and control branches of Lindera benzoin. Defoliating branches after fruit initiation significantly increased subsequent fruit abortion. Flowers that matured fruit had significantly more pollen tubes per style than those that initiated but then aborted fruit, but greater levels of pollen competition did not result in the production of larger seeds. On undefoliated control branches, selective abortion occurred only among flowers opening during the second half of the flowering season. On defoliated branches selective abortion occurred throughout the entire flowering season. Although defoliation increased abortion rate, it did not increase selectivity based on pollen tube number. When resources were depleted at the branch level, the position of the flower along the branch influenced whether a flower matured a fruit. Floral phenology was unrelated to position. The influence of position on fruit abortion was likely due to the patterns of resource acquisition and use.
Phenotypic Variation in a Zooplankton Egg Bank
Authors: Hairston Nelson G. , Kearns Colleen M. , Ellner Stephen P.
Published: May 2006

Dormant propagule pools may store potentially significant genetic variation that can influence the rate and direction of microevolution via directional selection, temporally fluctuating selection, and evolution of trait covariance between timing of emergence from the propagule pool and fitness characters expressed in the active population. The third process can interact with either of the first two to produce distinct effects. Each process can lead to a different distribution of genotypes and phenotypes between active and dormant subpopulations. We compared the phenotypic distributions of an important fitness character for individuals collected from active and diapausing subpopulations of a freshwater copepod, Diaptomus sanguineus, with a long—lived egg bank. The character, seasonal timing of the switch from production of immediately hatching eggs to diapausing eggs, determines the relative representation of copepods with different switch dates in future generations and is subject to fluctuating selection due to year—to—year changes in the timing and intensity of the seasonal onset of fish predation. The mean timing of diapause is significantly later in the season for copepods reared from long—lived diapausing eggs than it is for copepods reared from individuals collected from the water column. Phenotypic variance for diapause timing does not differ between the two subpopulations. Within the sediment subpopulation, the distribution of diapause timing depends upon two features of the diapausing eggs: (1) individuals originating from eggs near the sediment surface exhibit a slightly earlier switch date with greater phenotypic variance than individuals from deep in the sediments, and (2) individuals from eggs that hatched shortly after they were collected from sediments have a later seasonal switch to diapause than those that hatched later in time. We hypothesize that our results are explained by adaptive covariance between traits that influences how long an egg spends in the sediments before hatching and traits that influence the seasonal timing of diapause. The covariance may result from either phenotypic plasticity or from genetic covariance between diapause timing and hatching probability.
Scale‐Dependent Recolonization: The Role of Sediment Stability in a Dynamic Sandflat Habitat
Authors: Thrush S. F. , Whitlatch R. B. , Pridmore R. D. , Hewitt J. E. , Cummings V. J. , Wilkinson M. R.
Published: May 2006

An important ecological issue is developing an understanding of how patterns and processes vary with scale. We designed a field experiment to test how differences in the aerial extent of disturbance affected macrofaunal recolonization on a sandflat. Three different plot sizes (0.203 $m2$, 0.81 $m2$, and 3.24 $m2$) were dafaunted, and samples were collected to assess recovery over a 9—mo period. As the sandflat used for the experiment was prone to disturbance by wind—driven waves, we also measured changes in sediment bed height (an indicator of sediment stability) over the course of the experiment. Most common species revealed significant relationships between density and disturbance plot size. Scale—dependent recovery was also demonstrated by differences in species assemblage structure over the course of the experiment. Relative rates of colonization varied by $\approx$50% between large and small experimental plots. However, these differences were not related to specific species, particular functional groups, or potential modes of colonizations. The results revealed an unusually slow rate of faunal recovery following defaunation. Both increasing numbers of colonists, and density changes in ambient sediments made an important contribution to recovery. The relationship found between changes in sediment bed height and wind velocity indicated that wind—driven wave disturbance was an important factor influencing sediment instability. Sediment instability was higher in all experimental plots than in the ambient sediments, due to the initial removal of a dense spionid polychaete tube mat characteristically found at the study site. Sediment instability also increased with increasing plot size. Thus in this dynamic sandflat habitat, faunal emigration from recovering disturbed patches of sediment may significantly slow rates of recolonization. These results demonstrate that incorporating patch size, emigration, recovery time, and interactions between hydrodynamic conditions and habitat stability (particularly where colonists influence sediment stability) are crucial to generating a general understanding of recovery processes in sof—sediment habitats. While our results demonstrate the need for caution in scaling—up from small—scale studies, they do indicate that larger scale disturbances that destroy organisms with a role in maintaining habitat stability are likely to result in very slow recovery dynamics, particularly in wave—disturbed soft—sediment habitats.
Responses of a C4 Grass and Three C3 Forbs to Variation in Nitrogen and Light in Tallgrass Prairie
Authors: Turner C. L. , Knapp A. K.
Published: May 2006

In tallgrass prairie, high plant species diversity results not from a large number of grass species, but from a large number of forb (nongrass, herbaceous) species. Forbs exhibit morphological, life history, and ecophysiological characteristics that contrast sharply with those of the dominant C4 grasses. Success of the subdominant forbs varies strongly with topographic position and burning regime, and landscape scale patterns of abundance are well documented. But comparatively little is known about the mechanisms determining these patterns in persistent tallgrass prairie forbs. To elucidate these mechanisms, (1) leaf—level physiological characteristics of the dominant C4 grass, Andropogon gerardii, and four co—occurring C3 forbs were measured in response to natural and experimentally manipulated gradients of N availability, and (2) seasonal light environments of forbs in contrasting topographic positions and burning regimes and their morphological and physiological responses in these environments were compared to determine whether resource availability and utilization patterns contributed to patterns of forb distribution and abundance. The effects of burning regime and topographic position on maximum rate of photosynthesis (A) and stomatal conductance to water vapor (g) measured at the leaf level were not consistent with patterns of forb abundance. Nitrogen did not appear to limit forb physiological processes, even though increased N availability resulted in higher tissue N concentrations and greater biomass. There was no consistent increase in (A) or decrease in (g) in response to fertilization. However, (A) at low light levels was as much as 67% higher in fertilized Vernonia baldwinii and A. gerardii compared to unfertilized plants. Greater light availability to forbs in the canopy was associated with lower grass biomass production in uplands compared to lowlands and in unburned compared to burned sites. Forbs did not appear to adjust morphologically (leaf area and plant height) to different light environments at different sites. As a result, as much as 90% of forb leaf area in the burned lowland was displayed in low light, whereas as little as 30% of forb leaf area was in low light in the uplands at midseason. Estimates of potential whole—plant carbon uptake, based on leaf area distribution relative to available light and (A) as a function of light availability, agreed well with patterns of forb abundance and production. Differences in light availability may account for much of the variability in forb abundance related to burning regime and topographic position by limiting carbon gain in forbs more in burned lowlands than in other sites.
Perturbation and Resilience: A Long‐Term, Whole‐Lake Study of Predator Extinction and Reintroduction
Authors: Mittelbach Gary G. , Turner Andrew M. , Hall Donald J. , Rettig Jessica E. , Osenberg Craig W.
Published: May 2006

This paper presents the results of a long—term study of changing predator densities and cascading effects in a Michigan lake in which the top carnivore, the largemouth bass (Micropterus salmoides), was eliminated in 1978 and then reintroduced in 1986. The elimination of the bass was followed by a dramatic increase in the density of planktivorous fish, the disappearance of large zooplankton (e.g., two species of Daphnia that had historically dominated the zooplankton community), and the appearance of a suite of small—bodied cladoceran (zooplankton) species. The system remained in this state until bass were reintroduced. As the bass population increased, the system showed a steady and predictable return to its previous state; planktivore numbers declined by two orders of magnitude, large—bodied Daphnia reappeared and again dominated the zooplankton, and the suite of small—bodied cladocerans disappeared. Within each cladoceran species there was a steady increase in mean adult body size as planktivore numbers declined. Total zooplankton biomass increased ≈ 10—fold following the return of large—bodied Daphnia, and water clarity increased significantly with increases in Daphnia biomass and total cladoceran biomass. These changes in community structure and trophic—level biomasses demonstrate the strong impact of removing a single, keystone species, and the capacity of the community to return to its previous state after the species is reintroduced.
Critical Thresholds in Species' Responses to Landscape Structure
Authors: With Kimberly A. , Crist Thomas O.
Published: May 2006

Critical thresholds are transition ranges across which small changes in spatial pattern produce abrupt shifts in ecological responses. Habitat fragmentation provides a familiar example of a critical threshold. As the landscape becomes dissected into smaller parcels of habitat, landscape connectivity–the functional linkage among habitat patches–may suddenly become disrupted, which may have important consequences for the distribution and persistence of populations. Landscape connectivity depends not only on the abundance and spatial patterning of habitat, but also on the habitat specificity and dispersal abilities of species. Habitat specialists with limited dispersal capabilities presumably have a much lower threshold to habitat fragmentation than highly vagile species, which may perceive the landscape as functionally connected across a greater range of fragmentation severity. To determine where threshold effects in species' responses to landscape structure are likely to occur, we developed a simulation model modified from percolation theory. Our simulations predicted the distributional patterns of populations in different landscape mosaics, which we tested empirically using two grasshopper species (Orthoptera: Acrididae) that occur in the shortgrass prairie of north—central Colorado. Increasing degree of habitat specialization and dispersal range of a species enhanced the level of aggregation–the degree of clumping exhibited by the population–in our simulations. The landscape threshold at which populations became aggregated was affected by dispersal range for habitat generalists, but not for habitat specialists. Habitat specialists exhibited aggregated populations when preferred habitat occupied <40% of the landscape. Habitat generalists with good dispersal abilities occurred as aggregated populations when <35% of the landscape contained suitable habitat; habitat generalists with limited dispersal only formed patchy distributions when the preferred habitat was a minor (20%) proportion of the habitat. In field tests, a large species of grasshopper (Xanthippus corallipes Haldeman) exhibited reduced rates of travel in two microhabitats that together comprised 35% of a grassland mosaic; a smaller species (Psoloessa delicatula Scudder) had the highest residence time in a rare microhabitat that occurred in only 8% of the landscape. On the basis of our simulation results, we predicted that the large species would be patchily distributed because the abundance of its associated habitat is at the critical threshold. The small species should be unable to aggregate, given the rarity of habitat for which it has an affinity, and thus should be randomly distributed across the landscape. The distribution of these two species in this grassland mosaic matched the predictions from our simulations. By providing quantitative predictions of threshold effects, this modelling approach may prove useful in the formulation of conservation strategies and assessment of land—use changes on species' distributional patterns and persistence.
Life Cycle Trade‐Offs in Matrix Population Models
Authors: van Tienderen Peter H.
Published: May 2006

Matrix projections allow identification of those phases in the life cycle with a high potential impact on the population growth rate. This impact is assessed by the sensitivity or elasticity of the matrix elements that are computed from life cycle data such as age—dependent survival or fecundity. Covariation among life cycle components, e.g., due to trade—offs, is a main subject of life history theory. Sensitivities or elasticities of matrix elements do not take this covariation into account. Integrated sensitivities and elasticities measure the net effect of a matrix element, combining its direct effect and indirect effects through correlation with other matrix elements. These measures are related to the selection differentials and expected selection responses from quantitative genetics. The use of these measures is illustrated with data on disease resistance in a perennial weed Plantago lanceolata, and the demography of killer whale pods.
Ecological Controls over Monoterpene Emissions from Douglas‐Fir (Pseudotsuga Menziesii)
Authors: Lerdau Manuel , Matson Pamela , Fall Ray , Monson Russell
Published: May 2006

The roles of nitrogen availability and seasonality in controlling monoterpene concentration in and emission from Douglas—fir (Pseudotsuga menziesii) were examined in a greenhouse study. Plants were maintained at three nitrogen levels, and foliar nitrogen concentration, photosynthetic rate, monoterpene concentration, and monoterpene emission rate were measured over an entire phenological cycle, from before bud break in the spring through winter dormancy. Both nitrogen fertilization level and phenological stage affected the concentration of monoterpenes in the foliage. There was also a consistent linear relationship between monoterpene concentration and monoterpene emission. Out of the nitrogen—phenology—concentration and the concentration—emission relationships comes a predictable relationship between nitrogen, phenology and monoterpene emission. This relationship allows linkage between atmospheric chemical processes, such as ozone production, and ecological ones, such as leaf expansion. The results also demonstrate that theories on allocation to defense need to consider the phenological stage of the plant as well as the availability of resources.
Longitudinal Management of Dementia in Primary Care
Authors: Moo Lauren R.
Published: March 2024

This Viewpoint describes the positive role that primary care teams can play in the lives of patients with dementia and the families that care for them.
Associations of Medical Debt With Health Status, Premature Death, and Mortality in the US
Authors: Han Xuesong , Hu Xin , Zheng Zhiyuan , Shi Kewei Sylvia , Yabroff K. Robin
Published: March 2024

Importance

Medical debt is increasingly common in the US. Little is known regarding its association with population health.

Objective

To examine the associations of medical debt with health status, premature death, and mortality at the county level in the US.

Design, Setting, and Participants

This cross-sectional study was conducted at the US county level using 2018 medical debt data from the Urban Institute Debt in America project linked with 2018 data on self-reported health status and premature death from the County Health Rankings & Roadmaps and with 2015 to 2019 mortality data from the National Center for Health Statistics. Data analysis was performed from August 2022 to May 2023.

Exposure

Share of population with any medical debt in collections and median amount of medical debt.

Main Outcomes and Measures

Health status was measured as (1) the mean number of physically and mentally unhealthy days in the past 30 days per 1000 people, (2) the mean number of premature deaths measured as years of life lost before age 75 years per 1000 people, and (3) age-adjusted all-cause and 18 cause-specific mortality rates (eg, malignant cancers, heart disease, and suicide) per 100 000 person-years. Multivariable linear models were fitted to estimate the associations between medical debt and health outcomes.

Results

A total of 2943 counties were included in this analysis. The median percentage of the county population aged 65 years or older was 18.3% (IQR, 15.8%-20.9%). Across counties, a median 3.0% (IQR, 1.2%-11.9%) of the population were Black residents, 4.3% (IQR, 2.3%-9.7%) were Hispanic residents, and 84.5% (IQR, 65.7%-93.3%) were White residents. On average, 19.8% (range, 0%-53.6%) of the population had medical debt. After adjusting for county-level sociodemographic characteristics, a 1–percentage point increase in the population with medical debt was associated with 18.3 (95% CI, 16.3-20.2) more physically unhealthy days and 17.9 (95% CI, 16.1-19.8) more mentally unhealthy days per 1000 people during the past month, 1.12 (95% CI, 1.03-1.21) years of life lost per 1000 people, and an increase of 7.51 (95% CI, 6.99-8.04) per 100 000 person-years in age-adjusted all-cause mortality rate. Associations of medical debt and elevated mortality rates were consistent for all leading causes of death, including cancer (1.12 [95% CI, 1.02-1.22]), heart disease (1.39 [95% CI, 1.21-1.57]), and suicide (0.09 [95% CI, 0.06-0.11]) per 100 000 person-years. Similar patterns were observed for associations between the median amount of medical debt and the aforementioned health outcomes.

Conclusions and Relevance

These findings suggest that medical debt is associated with worse health status, more premature deaths, and higher mortality rates at the county level in the US. Therefore, policies increasing access to affordable health care, such as expanding health insurance coverage, may improve population health.
Association between subjective well‐being and cognition of neighborhood places: An online questionnaire study conducted in the Tokyo metropolitan area
Authors: Takamine Shota , Goto Haruhiko , Lin Shu‐hsien , Yamakawa Yukinori
Published: March 2024

Improving individuals' subjective well‐being has become a focus of policymaking globally in recent times. The current study examined the association between cognition of neighborhood places and subjective well‐being, with the aim of informing urban planning and community development efforts to improve the latter. An online questionnaire was distributed among residents in the Tokyo metropolitan area, and 2600 individuals responded. Regression analysis showed that respondents with greater neighborhood awareness and higher levels of education and household income exhibited better subjective well‐being. Moreover, psychological distress, loneliness, and sense of coherence were observed to be associated with amount of cognition of neighborhood places. Another regression analysis revealed that amount of cognition of neighborhood places was associated with education levels and household income independently, suggesting the possibility of amount of cognition of neighborhood places playing a mediatory role in health disparities, a global public health concern. The findings of the current study suggest that urban planning and community development policies should aim to increase individuals' amount of cognition of neighborhood places by improving accessibility and providing information on the history, available facilities, and culture of their neighborhood. These measures should also be conducted in areas with residents from lower socioeconomic strata.
Selective Extraction of Critical Metals from Spent Li‐Ion Battery Cathode: Cation–Anion Coordination and Anti‐Solvent Crystallization
Authors: Lyu Yanqiu , Yuwono Jodie A. , Fan Yameng , Li Jingxi , Wang Jingxiu , Zeng Rong , Davey Kenneth , Mao Jianfeng , Zhang Chaofeng , Guo Zaiping
Published: March 2024

Owing to continuing global use of lithium‐ion batteries (LIBs), in particular in electric vehicles (EVs), there is a need for sustainable recycling of spent LIBs. Deep eutectic solvents (DESs) are reported as “green solvents” for low‐cost and sustainable recycling. However, the lack of understanding of the coordination mechanisms between DESs and transition metals (Ni, Mn and Co) and Li makes selective separation of transition metals with similar physicochemical properties practically difficult. Here, it is found that the transition metals and Li have a different stable coordination structure with the different anions in DES during leaching. Further, based on the different solubility of these coordination structures in anti‐solvent (acetone), a leaching and separation process system is designed, which enables high selective recovery of transition metals and Li from spent cathode LiNi1/3Co1/3Mn1/3O2 (NCM111), with recovery of acetone. Recovery of spent LiCoO2 (LCO) cathode is also evidenced and a significant selective recovery for Co and Li is established, together with recovery and reuse of acetone and DES. It is concluded that the tuning of cation–anion coordination structure and anti‐solvent crystallization are practical for selective recovery of critical metal resources in the spent LIBs recycling.
Discovery of Selective and Potent ATR Degrader for Exploration its Kinase‐Independent Functions in Acute Myeloid Leukemia Cells
Authors: Wang Yubo , Wang Ruonan , Zhao Yanli , Cao Sheng , Li Chen , Wu Yanjie , Ma Lan , Liu Ying , Yao Yuhong , Jiao Yue , Chen Yukun , Liu Shuangwei , Zhang Kun , Wei Mingming , Yang Cheng , Yang Guang
Published: March 2024

ATR has emerged as a promising target for anti‐cancer drug development. Several potent ATR inhibitors are currently undergoing various stages of clinical trials, but none have yet received FDA approval due to unclear regulatory mechanisms. In this study, we discovered a potent and selective ATR degrader. Its kinase‐independent regulatory functions in acute myeloid leukemia (AML) cells were elucidated using this proteolysis‐targeting chimera (PROTAC) molecule as a probe. The ATR degrader, 8 i, exhibited significantly different cellular phenotypes compared to the ATR kinase inhibitor 1. Mechanistic studies revealed that ATR deletion led to breakdown in the nuclear envelope, causing genome instability and extensive DNA damage. This would increase the expression of p53 and triggered immediately p53‐mediated apoptosis signaling pathway, which was earlier and more effective than ATR kinase inhibition. Based on these findings, the in vivo anti‐proliferative effects of ATR degrader 8 i were assessed using xenograft models. The degrader significantly inhibited the growth of AML cells in vivo, unlike the ATR inhibitor. These results suggest that the marked anti‐AML activity is regulated by the kinase‐independent functions of the ATR protein. Consequently, developing potent and selective ATR degraders could be a promising strategy for treating AML.
Promoted catalytic performance of sugarcane bagasse ash supported by γ‐alumina as efficient, stable, and ecofriendly catalyst for dehydration of methanol to dimethyl ether
Authors: Said Abd El‐Aziz A. , Goda Mohamed N. , Abd El‐Wahab Mohamed M. M. , El‐Gamal Nadia O. , El‐Aal Mohamed Abd
Published: March 2024

The aim of this study was to use different proportions (1% to 20% by weight) of γ‐alumina to modify sugarcane bagasse ash (SCBA) for the production of dimethyl ether (DME) through the dehydration of methyl alcohol. A simple precipitation method was utilized to fabricate (1–20 wt.%) Al2O3/SCBA catalysts. X‐ray fluorescence, X‐ray diffraction, Fourier‐transform infrared spectroscopy, transmission electron microscopy, and N2 sorption were used to explore the structural, spectroscopic, morphological, and textural features. The XRD pattern of Al2O3/SCBA catalysts showed a new peak that corresponded to the formation of γ‐Al2O3. In addition, the average crystallite sizes of pure SCBA and 10% and 20%Al2O3/SCBA catalysts were calculated and found to be 20.1, 21.6, and 22.6 nm, respectively. To evaluate the acidity of these catalysts, the dehydration of isopropyl alcohol and the chemisorption of basic probe molecules were employed. The acidity test results displayed that these catalysts have weak to moderate acidic sites. The 10% Al2O3/SCBA catalyst calcined at 400°C showed high efficiency for the conversion of methyl alcohol to DME, attaining 89% conversion with 100% selectivity. This observation can be attributed to the even distribution of active sites and the acid–base equilibrium on the surface. Moreover, its catalytic activity and selectivity remain unchanged over a continuous 2‐week operation without coke formation, demonstrating its extremely high stability. A strong correlation was observed between the catalytic activity and both the surface area and acidity of the catalysts.
Phosphatidic Acid Promoting the Generation of Interleukin‐17A Producing Double‐Negative T Cells by Enhancing mTORC1 Signaling in Lupus
Authors: Li Wenjing , Tang Xiaojun , Zheng Yuanyuan , Xu Xuefeng , Zhao Nan , Tsao Betty P. , Feng Xuebing , Sun Lingyun
Published: March 2024

Objective

The goal was to investigate the role and intracellular regulatory mechanisms of double‐negative T (DNT) cells in the pathogenesis of systemic lupus erythematosus (SLE).

Methods

DNT cells were assessed in murine models, patients with SLE, and controls using flow cytometry (FCM). DNT cells from either resiquimod (R848) or vehicle‐treated C57BL/6 (B6) mice were cultured with B cells from R848‐treated mice to explore functions. Differential mechanistic target of rapamycin (mTOR) pathway signaling in DNT cells measured using FCM and quantitative polymerase chain reaction was validated by rapamycin inhibition. Candidate lipid metabolites detected using liquid chromatography with electrospray ionization mass spectrometry/mass spectrometry were functionally assessed in DNT cell cultures.

Results

DNT cells were markedly increased in both spontaneous and induced mouse lupus models and in patients with SLE. Expanded DNT cells from R848‐treated B6 mice produced elevated interleukin (IL)‐17A and IgG with increased germinal center B (GCB) cells. Expansion of DNT cells associated with activation of mTORC1 pathway that both IL‐17A levels and the number of DNT cells exhibited dose‐dependent reduction with rapamycin treatment. Lipidomics studies revealed differential patterns of lipid metabolites in T cells of R848‐treated mice. Among candidate metabolites, elevated phosphatidic acid (PA) that was partially controlled by phospholipase D2 increased the expression of the mTORC1 downstream target p‐S6 and positively expanded IL‐17A–producing DNT cells. Similarly, elevated proportions of circulating DNT cells in patients with SLE correlated with disease activity and proteinuria, and IL‐17A secretion was elevated after in vitro PA stimulation.

Conclusion

The accumulation of PA in T cells could activate the mTORC1 pathway, promoting DNT cell expansion and IL‐17A secretion, resulting in GCB cell abnormalities in lupus.

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Observer‐based dual event‐triggered control for non‐weighted L2‐gain of switched linear systems
Authors: Zhang Ziyu , Yang Xinsong , Park Ju H. , Xu Zhilu
Published: March 2024

As everyone knows, strict mode‐dependent event‐triggered mechanism (MDETM) is rarely studied for switched systems due to the difficulty in settling down the relationship between the dwell time (DT) and triggered intervals. This problem is satisfactorily solved by considering the exponential stabilization via observer‐based dual MDETMs in switched linear systems. The dual MDETMs on the sensor‐controller (S‐C) channel and controller‐actuator (C‐A) channel are designed respectively according to mode‐dependent average dwell time (MDADT). The MDETMs on the C‐A channel are generated based on the MDETMs on the S‐C channel, which makes the new control technique strict mode‐dependent and reduces conservatism as much as possible. Furthermore, when there exists external disturbance, a non‐weighted
‐gain with better performance than existing results is given. By studying an augmented system, exponential stabilization is achieved through a new event‐triggered state estimation (ETSE) and dual MDETMs. The observer gain, controller gain, and non‐weighted
‐gain are derived through an effective algorithm. Finally, two numerical examples are given to illustrate the effectiveness of theoretical research.
Utility of green chemistry for sustainable fluorescence derivatization approach for spectrofluorimetric quantification of Darolutamide as antineoplastic drug in pharmaceutical formulation and spiked human plasma
Authors: Salem Hesham , Abdelmajed Mahmoud A. , Rabiey Mahmoud , Saied Omar , Amir Michael , Abdelgalil Mahmoud
Published: March 2024

Darolutamide is an oral nonsteroidal androgen receptor antagonist used to delay the process of prostate cancer to metastatic disease and to increase the quality of life for people with advanced prostate cancer. Here, a second spectrofluorimetric method was advanced for quantifying Darolutamide in pharmaceutical formulation and spiked human plasma. This method depends on the fluorescence derivatization of Darolutamide with 4‐chloro‐7‐nitrobenzo‐2‐oxa‐1,3‐diazole (NBD‐Cl) at 75°C in a (pH 9) of borate buffer to produce a fluorescent derivative that can be detected at 520 nm after excitation at 460 nm. The method has been validated using ICH criteria, and it demonstrated linearity in the range 5–200 ng ml−1. The limit of detection (LOD) and limit of quantitation (LOQ) were 1.15 and 3.84 nm, respectively. The proposed method was applied precisely and accurately for quantifying Darolutamide within the pharmaceutical formulation and spiking human plasma without any interferences. Moreover, the method's sustainability was evaluated and compared with the published method using two greenness assessment tools termed analytical eco‐scale and Analytical GREEnness (AGREE). These findings suggest that the method is more sustainable than the published method.
Sustainability practices and firm performance: The moderating role of firm‐, industry‐, and country‐level factors
Authors: Siregar Sylvia Veronica , Mita Aria Farah , Amarullah Fitriany , Mahmud Radziah
Published: March 2024

The purpose of this study is to examine the effect of sustainability practices on firm performance and the moderating role of firm, industry, and country‐level factors on that association. The samples of our study are listed firms in ASEAN 5 (Indonesia, Singapore, Malaysia, Thailand, and the Philippines), with total observations are 1069 from the years 2004–2019. We use regression analysis to test our hypotheses. We find that sustainability performance has a significant positive association with firm performance, which supports our prediction. By engaging in socially responsible activities, companies can gain trust and loyalty from customers and other stakeholders, maintain their competitive advantage, and thus higher financial performance. However, there are no significant differences in the financial performance between firms that issue stand‐alone sustainability reports and those that do not. We cannot find any significant moderating role of the firm, industry‐, and country‐level factors on the association between sustainability practices and firm performance. We have not found any extant studies that have examined firm‐, industry‐, and country‐level factors simultaneously on the association between sustainability practices and firm performance. Our study also contributes to a better understanding of the impact of sustainability practices on firm performance in ASEAN, where sustainability practices are expected to be in greater demand than in mature markets due to the higher social and environmental concerns in such regions.
Effects of Naphthoquinones from the Roots of Onosma Armeniacum Klokov on Wound Healing
Authors: Küpeli Akkol Esra , Subaş Tuğba , Özgen Ufuk , Süntar Ipek , Ilhan Mert , Keleş Hikmet
Published: March 2024

In Turkish folk medicine, the roots of Onosma armeniacum Klokov are used to heal wounds, burns, hemorrhoids, hoarseness, dyspnea, stomach ulcers, and abdominal aches. The objective was to evaluate the plant‘s ethnopharmacological applications using in vivo pharmacological experimental models. In vivo linear incision and circular excision the wound models were used to assess the wound healing activity along with histopathological investigation. The active component(s) were isolated and identified after being exposed to several chromatographic separation procedures on the primary extract. The n‐hexane‐dichloromethane mixture extract was subjected to chromatographic separation after the wound‐healing activity was confirmed. Deoxyshikonin (1), β,β‐dimethylacrylshikonin (2), α‐methyl‐n‐butylshikonin (3), isovalerylshikonin (4), acetylshikonin (5), β‐hydroxyisovalerylshikonin (6), and 5,8‐O‐dimethylacetylshikonin (7) were identified as the structures of the isolated compounds. The efficacy of O. armeniacum to heal wounds was investigated in this study. Shikonin derivatives were identified as the primary active components of the roots by bioassay‐guided fractionation and isolation procedures.