The properties and environment of primitive solar nebulae as deduced from observations of solar-type pre-main sequence stars

The following topics were discussed: (1) current observation evidence for the presence of circumstellar disks associated with solar type pre-main sequence (PMS) stars; (2) the properties of such disks; and (3) the disk environment

The evolution of young stellar object disks and their environment

The main efforts were directed towards determining the frequency of disk occurrence and the timescales for disk evolution for solar-type and intermediate mass stars. The results of the investigation showed that optically thick disks are accretion disks. The projected accomplishments are also discussed

Equilibrating temperature-like variables in jammed granular subsystems

Although jammed granular systems are athermal, several thermodynamic-like descriptions have been proposed which make quantitative predictions about the distribution of volume and stress within a system and provide a corresponding temperature-like variable. We perform experiments with an apparatus designed to generate a large number of independent, jammed, two-dimensional configurations. Each configuration consists of a single layer of photoelastic disks supported by a gentle layer of air. New configurations are generated by alternately dilating and re-compacting the system through a series of boundary displacements. Within each configuration, a bath of particles surrounds a smaller subsystem of particles with a different inter-particle friction coefficient than the bath. The use of photoelastic particles permits us to find all particle positions as well as the vector forces at each inter-particle contact. By comparing the temperature-like quantities in both systems, we find compactivity (conjugate to the volume) does not equilibrate between the systems, while the angoricity (conjugate to the stress) does. Both independent components of the angoricity are linearly dependent on the hydrostatic pressure, in agreement with predictions of the stress ensemble

Water quality impacts and river system recovery following the 2014 Mount Polley mine tailings dam spill, British Columbia, Canada

The Mount Polley mine tailings embankment breach on August 4th 2014, in British Columbia, Canada, is the second largest mine waste spill on record. The mine operator responded swiftly by removing significant quantities of tailings from the primary receiving watercourse, stabilizing the river corridor and beginning construction of a new river channel. This presented a unique opportunity to study spatial patterns of element cycling in a partially-restored and alkaline river system. Overall, water quality impacts are considered low with Cu, and to a lesser extent V, being the only elements of concern. However, the spatial pattern of stream Cu loading suggested chemical (dominant at low flow) and physical (dominant at high flow) mobilization processes operating in different parts of the watershed. Chemical mobilization was hypothesized to be due to Cu sulfide (chalcopyrite) oxidation in riparian tailings and reductive dissolution of Cu-bearing Fe oxides in tailings and streambed sediments whereas physical mobilization was due to erosion and suspension of Cu-rich stream sediments further downstream. Although elevated aqueous Cu was evident in Hazeltine Creek, this is considered a relatively minor perturbation to a watershed with naturally elevated stream Cu concentrations. The alkaline nature of the tailings and the receiving watercourse ensures most aqueous Cu is rapidly complexed with dissolved organic matter or precipitates as secondary mineral phases. Our data highlights how swift removal of spilled tailings and river corridor stabilization can limit chemical impacts in affected watersheds but also how chemical mobilization (of Cu) can still occur when the spilled tailings and the receiving environment are alkaline. We present a conceptual model of Cu cycling in the Hazeltine Creek watershed.publishersversionPeer reviewe

The meaning of postpartum sexual health for women living in Spain : a phenomenological inquiry

Sexual health is a multidimensional phenomenon constructed by personal, social, and cultural factors but continues to be studied with a biomedical approach. During the postpartum period, a woman transitions to mother, as well as partner-to-parent and couple-to-family. There are new realities in life in the postpartum period, including household changes and new responsibilities that can impact the quality of sexual health. This phenomenon is understudied especially in the context of Spain. The purpose of this study was to describe the lived experience of postpartum sexual health among primiparous women giving birth in Catalonia (Spain). This was a phenomenological study with a purposive sample of primiparous women. Data was collected through semi-structured interviews until saturation. Analysis followed Colaizzi's seven-step process with an eighth translation step added to limit cross-cultural threats to validity. Also, the four dimensions of trustworthiness were established through strategies and techniques during data collection and analysis. Ten women were interviewed from which five themes emerged, including: Not feeling ready, inhibiting factors, new reality at home, socio-cultural factors, and the clinician within the health system. Returning to sexual health led women to engage in experiential learning through trial and error. Most participants reported reduced libido, experienced altered body image, and recounted resumption of sexual activity before feeling ready. A common finding was fatigue and feeling overloaded by the demands of the newborn. Partner support was described as essential to returning to a meaningful relationship. Discussions about postpartum sexual health with clinicians were described as taboo, and largely absent from the care model. Evidence-based practices should incorporate the best evidence from research, consider the postpartum sexual health experiences and preferences of the woman, and use clinician expertise in discussions that include the topic of postpartum sexual health to make decisions. As such, human caring practices should be incorporated into clinical guidelines to recognize the preferences of women. Clinicians need to be authentically present, engage in active communication, and individualize their care. More qualitative studies are needed to understand postpartum sexual health in different contexts, cultures, and countries and to identify similarities and differences through meta-synthesis

Microbial abundance in surface ice on the Greenland Ice Sheet

Measuring microbial abundance in glacier ice and identifying its controls is essential for a better understanding and quantification of biogeochemical processes in glacial ecosystems. However, cell enumeration of glacier ice samples is challenging due to typically low cell numbers and the presence of interfering mineral particles. We quantified for the first time the abundance of microbial cells in surface ice from geographically distinct sites on the Greenland Ice Sheet (GrIS), using three enumeration methods: epifluorescence microscopy (EFM), flow cytometry (FCM), and quantitative polymerase chain reaction (qPCR). In addition, we reviewed published data on microbial abundance in glacier ice and tested the three methods on artificial ice samples of realistic cell (10(2)–10(7) cells ml(−1)) and mineral particle (0.1–100 mg ml(−1)) concentrations, simulating a range of glacial ice types, from clean subsurface ice to surface ice to sediment-laden basal ice. We then used multivariate statistical analysis to identify factors responsible for the variation in microbial abundance on the ice sheet. EFM gave the most accurate and reproducible results of the tested methodologies, and was therefore selected as the most suitable technique for cell enumeration of ice containing dust. Cell numbers in surface ice samples, determined by EFM, ranged from ~ 2 × 10(3) to ~ 2 × 10(6) cells ml(−1) while dust concentrations ranged from 0.01 to 2 mg ml(−1). The lowest abundances were found in ice sampled from the accumulation area of the ice sheet and in samples affected by fresh snow; these samples may be considered as a reference point of the cell abundance of precipitants that are deposited on the ice sheet surface. Dust content was the most significant variable to explain the variation in the abundance data, which suggests a direct association between deposited dust particles and cells and/or by their provision of limited nutrients to microbial communities on the GrIS

Mechanisms of goethite dissolution in the presence of desferrioxamine B and Suwannee River fulvic acid at pH 6.5

Siderophores are Fe3+ specific low MW chelating ligands secreted by microorganisms in response to Fe stress. Low MW organic acids such as oxalate have been shown to enhance siderophore mediated dissolution of Fe3+ oxides. However, the effect of fulvic acid presence on siderophore function remains unknown. We used batch dissolution experiments to investigate Fe release from goethite in the goethite-fulvic acid desferrioxamine B (goethite-SRFA-DFOB) ternary system. Experiments were conducted at pH 6.5 while varying reagent addition sequence. FTIR and UV-Vis spectroscopy were employed to characterise the Fe-DFOB, Fe-SRFA and DFOB–SRFA complexes. Iron released from goethite in the presence of SRFA alone was below detection limit. In the presence of both SRFA and DFOB, dissolved Fe increased with reaction time, presence of the DFOB-SRFA complex, and where SRFA was introduced prior to DFOB. FTIR data show that in the ternary system, Fe3+ is complexed primarily to oxygen of the DFOB hydroxamate group, whilst the carboxylate C=O of SRFA forms an electrostatic association with the terminal NH3+ of DFOB. We propose that SRFA sorbed to goethite lowers the net positive charge of the oxide surface, thus facilitating adsorption of cationic DFOB and subsequent Fe3+ chelation and release. Furthermore, the sorbed SRFA weakens Fe-O bonds at the goethite surface, increasing the population of kinetically labile Fe. This work demonstrates the positive, though indirect role of SRFA in increasing the bioavailability of Fe3+

A “Learning Revolution”? Investigating Pedagogic Practices around Interactive Whiteboards in British Primary Classrooms

Interactive whiteboards have been rapidly introduced into all primary schools under UK Government initiatives. These large, touch-sensitive screens, which control a computer connected to a digital projector, seem to be the first type of educational technology particularly suited for whole-class teaching and learning. Strong claims are made for their value by manufacturers and policy makers, but there has been little research on how, if at all, they influence established pedagogic practices, communicative processes and educational goals. This study has been designed to examine this issue, using observations in primary (elementary) school classrooms. It is funded by the UK Economic and Social Research Council and builds on the authors’ previous research on ICT in educational dialogues and collaborative activities

Discharge Age and Weight for Very Preterm Infants in Six Countries: 2012-2020

BACKGROUND Postmenstrual age for surviving infants without congenital anomalies born at 24-29 weeks' gestational age from 2005 to 2018 in the USA increased 8 days, discharge weight increased 316 grams, and median discharge weight z-score increased 0.19 standard units. We asked whether increases were observed in other countries. METHODS We evaluated postmenstrual age, weight, and weight z-score at discharge of surviving infants without congenital anomalies born at 24-29 weeks' gestational age admitted to Vermont Oxford Network member hospitals in Austria, Ireland, Italy, Switzerland, the UK, and the USA from 2012 to 2020. RESULTS After adjustment, the median postmenstrual age at discharge increased significantly in Austria (3.6 days, 99% CI [1.0, 6.3]), Italy (4.0 days [2.3, 5.6]), and the USA (5.4 days [5.0, 5.8]). Median discharge weight increased significantly in Austria (181 grams, 99% CI [95, 267]), Ireland (234 [143, 325]), Italy (133 [83, 182]), and the USA (207 [194, 220]). Median discharge weight z-score increased in Ireland (0.24 standard units, 99% CI [0.12, 0.36]) and the USA (0.15 [0.13, 0.16]). Discharge on human milk increased in Italy, Switzerland, and the UK, while going home on cardiorespiratory monitors decreased in Austria, Ireland, and USA and going home on oxygen decreased in Ireland. CONCLUSIONS In this international cohort of neonatal intensive care units, postmenstrual discharge age and weight increased in some, but not all, countries. Processes of care at discharge did not change in conjunction with age and weight increases

Motherhood and decision-making among women living with HIV in developed countries: a systematic review with qualitative research synthesis

Background: Women living with HIV (WLH) lack evidence-based information about reproductive options while man‑ aging pressures from family, clinicians, and communities to give up the idea of having children. As the reproduction intentions of WLH are not well understood, stigmatizing behaviors force them to hide their disease to avoid rejection by their family, partner, and social networks. Compliance with social norms, fear of stigma, and discrimination infu‑ ence their experience. Current research is individual qualitative studies lacking the synthesis perspective necessary to guide intervention development. The purpose of this study was to synthesize the evidence to explain the reproduc‑ tive decision-making process for WLH in developed countries. Methods: A systematic review with qualitative research synthesis was conducted through searches in 10 elec‑ tronic databases (CINAHL, EMBASE, MEDLINE, Scopus, Social Science Citation Index, Web of Science, Google Scholar, Cuidatge, Cuiden Enfspo, and SciELO). Studies published in journals from 1995 to 2019 with qualitative data about reproductive decision-making among WLH in developed countries were eligible for inclusion. Developed country wasoperationalized by membership in the OECD for comparative conditions of social wellbeing and economic stability. The CASP and JBI checklists for qualitative research were used to assess study quality and methodological integrity. Thematic analysis and qualitative meta-summary techniques were used for the synthesis. Results: Twenty studies from 12 developed countries were included in the synthesis. Findings were organized into 3 meta-themes from 15 themes and 45 subthemes, including: (1) Shattered identity, (2) Barriers, inequities, and misinfor‑ mation, (3) Coping, resiliency, and support. Reproductive decision-making was perceived as a complex process infu‑ enced by facilitators and barriers. The facilitators helped WLH cope with their new situation to become more resilient, while the barriers made their situation more difcult to manage. Conclusion: WLH encounter reproductive decision-making with knowledge defcits and limited social support. An integrated approach to holistic care with comprehensive multidisciplinary counseling is needed to support WLH. Clinicians could beneft from professional development to learn how to be authentically present for WLH, including engaging in conversations, demonstrating compassion, and understanding situations. Evidence-based clinical prac‑ tice guidelines need to be tailored for the family planning and sexual health needs of WLH. Keywords: AIDS, HIV, Decision-making, Pregnancy, Reproductive health, Wome