Search

Studies of material returned from Cb asteroid Ryugu have revealed considerable mineralogical and chemical heterogeneity, stemming primarily from brecciation and aqueous alteration. Isotopic anomalies could have also been affected by delivery of exogenous clasts and aqueous mobilization of soluble elements. Here, we show that isotopic anomalies for mildly soluble Cr are highly variable in Ryugu and CI chondrites, whereas those of Ti are relatively uniform. This variation in Cr isotope ratios is most likely due to physicochemical fractionation between 54Cr-rich presolar nanoparticles and Cr-bearing secondary minerals at the millimeter-scale in the bulk samples, likely due to extensive aqueous alteration in their parent bodies that occurred [Formula: see text] after Solar System birth. In contrast, Ti isotopes were marginally affected by this process. Our results show that isotopic heterogeneities in asteroids are not all nebular or accretionary in nature but can also reflect element redistribution by water.

Preliminary analyses of asteroid Ryugu samples show kinship to aqueously altered CI (Ivuna-type) chondrites, suggesting similar origins. We report identification of C-rich, particularly primitive clasts in Ryugu samples that contain preserved presolar silicate grains and exceptional abundances of presolar SiC and isotopically anomalous organic matter. The high presolar silicate abundance (104 ppm) indicates that the clast escaped extensive alteration. The 5 to 10 times higher abundances of presolar SiC (~235 ppm), N-rich organic matter, organics with N isotopic anomalies (1.2%), and organics with C isotopic anomalies (0.2%) in the primitive clasts compared to bulk Ryugu suggest that the clasts formed in a unique part of the protoplanetary disk enriched in presolar materials. These clasts likely represent previously unsampled outer solar system material that accreted onto Ryugu after aqueous alteration ceased, consistent with Ryugus rubble pile origin.

The extraterrestrial materials returned from asteroid (162173) Ryugu consist predominantly of low-temperature aqueously formed secondary minerals and are chemically and mineralogically similar to CI (Ivuna-type) carbonaceous chondrites. Here, we show that high-temperature anhydrous primary minerals in Ryugu and CI chondrites exhibit a bimodal distribution of oxygen isotopic compositions: 16O-rich (associated with refractory inclusions) and 16O-poor (associated with chondrules). Both the 16O-rich and 16O-poor minerals probably formed in the inner solar protoplanetary disk and were subsequently transported outward. The abundance ratios of the 16O-rich to 16O-poor minerals in Ryugu and CI chondrites are higher than in other carbonaceous chondrite groups but are similar to that of comet 81P/Wild2, suggesting that Ryugu and CI chondrites accreted in the outer Solar System closer to the accretion region of comets.

Little is known about the origin of the spectral diversity of asteroids and what it says about conditions in the protoplanetary disk. Here, we show that samples returned from Cb-type asteroid Ryugu have Fe isotopic anomalies indistinguishable from Ivuna-type (CI) chondrites, which are distinct from all other carbonaceous chondrites. Iron isotopes, therefore, demonstrate that Ryugu and CI chondrites formed in a reservoir that was different from the source regions of other carbonaceous asteroids. Growth and migration of the giant planets destabilized nearby planetesimals and ejected some inward to be implanted into the Main Belt. In this framework, most carbonaceous chondrites may have originated from regions around the birthplaces of Jupiter and Saturn, while the distinct isotopic composition of CI chondrites and Ryugu may reflect their formation further away in the disk, owing their presence in the inner Solar System to excitation by Uranus and Neptune.

Here, a series of semi-interpenetrating polymer network (semi-IPN) hydrogels were synthesized and investigated hy combining three materials such as N-isopropylacrylamide (NIPAM), N,N'-diefhylacrylamide (DEA), and acrylic acid (AAc). The linear copolymer p(NIPAM-co-AAc) was introduced into DEA solution in the presence of N,N'-methylenebisacrylamide to synthesize p(NIPAM-co-AAc)/pDEA semi-IPN hydrogels using free radical polymerization. Scanning electron microscope images demonstrated the porous morphology of hydrogels with pore sizes in the range of 220-969 [micro]m. The physicochemical properties of polymers were evaluated by various characterization techniques, including gel permeation chromatography, dynamic light scattering, differential scanning calorimetry, rheological measurement, mechanical properties, and swelling behaviors. The results indicated that the introduction of linear copolymers into conventional hydrogels has significantly improved the properties of the hydrogels. Besides, the use of NIPAM has significantly improved the thermal sensitivity of the polymers in this work. Finally, a selected semi-IPN hydrogel was evaluated for its potential for the drug release of paracetamol. The sorption of paracetamol was an exothermic process that obeyed the Freundlich isotherms, with the highest sorption of 119.57 mg/g. The paracetamol release followed the Korsmeyer-Peppas model and was consistent with the Fickian diffusion mechanism. Key words: pH-thermoresponsive hydrogels, N-isopropylacrylamide, N,N'-diefhylacrylamide, acrylic acid, paracetamol, 1. Introduction A crosslinked hydrophilic polymer that is capable of absorbing water without dissolving is named hydrogel. Hydrogels sensitive to environmental stimuli such as temperature, pH, ionic strength, light, pressure, [...]

INTRODUCTION: Mechanisms explain how implementation strategies work. Implementation research requires careful operationalisation and empirical study of the causal pathway(s) by which strategies effect change, and factors that may amplify or weaken their effects. Understanding mechanisms is critically important to replicate findings, learn from negative studies or adapt an implementation strategy developed in one setting to another. Without understanding implementation mechanisms, it is difficult to design strategies to produce expected effects across contexts, which may have disproportionate effects on settings in which priority populations receive care. This manuscript outlines the protocol for an Agency for Healthcare Research and Quality-funded initiative to: (1) establish priorities for an agenda to guide research on implementation mechanisms in health and public health, and (2) disseminate the agenda to research, policy and practice audiences. METHODS AND ANALYSIS: A network of scientific experts will convene in Deep Dive meetings across 3 years. A research agenda will be generated through analysis and synthesis of information from six sources: (1) systematic reviews, (2) network members approaches to studying mechanisms, (3) new proposals presented in implementation proposal feedback sessions, (4) working group sessions conducted in a leading implementation research training institute, (5) breakout sessions at the Society for Implementation Research Collaborations (SIRC) 2019 conference and (6) SIRC conference abstracts. Two members will extract mechanism-relevant text segments from each data source and a third member will generate statements as an input for concept mapping. Concept mapping will generate unique clusters of challenges, and the network will engage in a nominal group process to identify priorities for the research agenda. ETHICS AND DISSEMINATION: This initiative will yield an actionable research agenda to guide research to identify and test mechanisms of change for implementation strategies. The agenda will be disseminated via multiple channels to solicit feedback and promote rigorous research on implementation mechanisms.

Volume status assessment in left ventricular assist device (LVAD) patients remains challenging. Cardiac resynchronization therapy (CRT) devices are common in LVAD patients, and the impedance across the CRT leads may be associated with hemodynamics and serve as a tool for noninvasive estimation of volume status. Ninety-one sets of measurements including cardiac filling pressures and lead impedances were prospectively obtained during ramp tests from 11 LVAD patients (65.5 ± 9.7 years old; nine male) with CRT devices. Right atrial (RA), right ventricular (RV), and left ventricular (LV) lead impedances were all significantly associated with central venous pressure (CVP) (p < 0.05). We derived the following equation: estimated CVP = 47.90-(0.086 × RA lead impedance) + (0.013 × RV lead impedance)-(0.020 × LV lead impedance). The estimated CVP had a significant correlation (r = 0.795) and good agreement with the measured CVP (mean difference -0.14 ± 1.77 mmHg). Applying the above equation on the validation cohort of twenty-one patients also maintained a strong association with measured CVP (r = 0.705). In conclusion, we have derived a novel equation to estimate CVP using lead impedance measurements. This finding may allow noninvasive monitoring of volume status in LVAD patients.

PURPOSE Despite the growing popularity of stepped-wedge cluster randomized trials (SW-CRTs) for practice-based research, the design's advantages and challenges are not well documented. The objective of this study was to identify the advantages and challenges of the SW-CRT design for large-scale intervention implementations in primary care settings. METHODS The EvidenceNOW: Advancing Heart Health initiative, funded by the Agency for Healthcare Research and Quality, included a large collection of SW-CRTs. We conducted qualitative interviews with 17 key informants from EvidenceNOW grantees to identify the advantages and challenges of using SW-CRT design. RESULTS All interviewees reported that SW-CRT can be an effective study design for largescale intervention implementations. Advantages included (1) incentivized recruitment, (2) staggered resource allocation, and (3) statistical power. Challenges included (1) time-sensitive recruitment, (2) retention, (3) randomization requirements and practice preferences, (4) achieving treatment schedule fidelity, (5) intensive data collection, (6) the Hawthorne effect, and (7) temporal trends. CONCLUSIONS The challenges experienced by EvidenceNOW grantees suggest that certain favorable real-world conditions constitute a context that increases the odds of a successful SW-CRT. An existing infrastructure can support the recruitment of many practices. Strong retention plans are needed to continue to engage sites waiting to start the intervention. Finally, study outcomes should be ones already captured in routine practice; otherwise, funders and investigators should assess the feasibility and cost of data collection. Key words: stepped wedge cluster randomized trial; practice improvement; study design; implementation; qualitative Ann Fam Med 2022;20:255-261. https://doi.org/10.1370/afm.2810, INTRODUCTION As a burgeoning study design in health services research, stepped-wedge cluster randomized trials (SW-CRTs) can have advantages over parallel CRTs in terms of statistical power and offer a pragmatic [...]

With the rapid increase in the aging population, more attention has been paid to studying older adults with dementia. Despite the fact that older adults with dementia are more likely to be abused compared to their cognitively intact counterparts, little attention has been paid to abuse within this population. This systematic review, conducted using the PRISMA model, aims to critically examine, evaluate, and synthesize literature on protective factors and adverse effects of elder abuse by informal caregivers among individuals with dementia. A search was undertaken using the Ageline, Medline, CINAHL, and PsycINFO databases for peer-reviewed articles published in English up to June 2023. A total of 291 articles were identified by the systematic search, and 8 articles were included in the review. The results showed that protective factors related to elder abuse are mainly examined at a perpetrator level, including caregiver-related, relational, and contextual factors. Adverse effects, specifically an increased risk of various medical conditions and poor medication adherence, were identified but less frequently discussed. The findings indicated future directions for practitioners, researchers, and policymakers to better serve older adults with dementia and their caregivers. [ABSTRACT FROM AUTHOR]

Background: Caregiving in the African American community is informed by strong cultural expectations but may be associated with negative experiences and poor mental health outcomes. Objective: The purpose of this convergent mixed-methods study is to understand the relationship between caregiving experiences and mental health and explore stress management strategies in African American family caregivers of adults with chronic or disabling conditions. Methods: African American family caregivers (N = 100) were recruited using community-engaged methods and completed a sociodemographic questionnaire, the Caregiver Reaction Assessment scale, and the Center for Epidemiologic Studies Depression (CES-D-10) Scale. A subsample (n = 24) participated in semi-structured interviews. Data were analyzed using linear regression and content analysis. A matrix was developed to integrate quantitative and qualitative results. Results: Participants were on average 59 years old. Most were women and provided care to a parent. Lack of family support (B = 1.37, P =.03) and impact of caregiving on caregivers' finances (B = 1.74, P =.004), schedule (B = 2.92, P <.001), and health (B = 3.26, P <.001) were associated with depressive symptoms and were reported as stressful experiences. Negative interactions with the care recipient and caring for multiple people emerged as other sources of stress. Participants used independent and interpersonal coping strategies, as well as strategies to facilitate their caregiving role to reduce their stress. Values of reciprocity, limited use of community-based resources, and mental health stigma emerged as important cultural considerations. Conclusions: Our findings suggest the need for culturally-sensitive interventions to improve communication and care coordination within African American family caregiving networks and educational programs about mental health and caregiving resources endorsed by trusted community sources. [ABSTRACT FROM AUTHOR]

We explore how insider trading returns, disparities in executive pay, and CEO turnover are interrelated. Our findings reveal both independent and interactive effects for insider trading returns, the CEO pay gap, and the likelihood of CEO turnover. First, an increase in abnormal returns from insider purchases lowers the probability of a CEO's turnover, while an increase in abnormal returns from insider sales increases the likelihood of a CEO's dismissal. Second, the CEO pay gap negatively affects the probability of CEO turnover for insider purchases, but it does not have a similar effect on insider sales. Third, the interaction between insider abnormal returns and any CEO pay disparity influences the impact of these returns on CEO turnover. Specifically, this interaction diminishes the positive effect of insider selling on the probability of a CEO's dismissal, offsets the negative effect of insider purchasing on CEO dismissal, and, finally, amplifies the negative impact of CEO pay disparity on the probability of a CEO's dismissal during periods witnessing insider purchases. [ABSTRACT FROM AUTHOR]

Friends are crucial for companionship, sharing personal thoughts and feelings, and are positively associated with psychological well-being and mental health. This is one of the first studies to provide an in-depth investigation of social support networks of African American friendship. Using a nationally representative sample of African American adults drawn from the National Survey of American Life, this study investigated sociodemographic correlates, as well as expanded information on marital status and life circumstances of friendships. Additionally, we examined the interrelationships among several aspects of friendship. The findings indicate that, apart from income and region, all other correlates (i.e. age, gender, education, marital status, material hardship, military service, incarceration history, parental status, and urbanicity) were significantly associated with involvement in friendship support networks (i.e. subjective friendship closeness, frequency of contact with friends, frequency of receiving support from friends, and frequency of providing support to friends). Moreover, subjective closeness to friends was positively associated with friend contact, and both subjective closeness to and contact with friends were positively associated with supportive exchanges with friends. These findings indicate the importance of understanding the life circumstances and contexts within which friendships occur and the need for much more quantitative and qualitative research on African American friendships. [ABSTRACT FROM AUTHOR]

We investigate how executive pay disparity affects insider profits around earnings news. Our findings reveal that high pay disparity is linked to higher abnormal returns from insider purchases before positive news, suggesting insiders exploit good news for greater gains. Conversely, it is associated with lower abnormal returns from insider sales before negative news, indicating less benefit from such sales. These insights highlight the influence of pay disparity on insider trading and underscore the importance of understanding this dynamic to improve decision-making and reduce misuse of insider information. [ABSTRACT FROM AUTHOR]