Impacts of climate and tree morphology on tree-ring stable isotopes in central Mongolia.

Recent climate extremes in Mongolia have ignited a renewed interest in understanding past climate variability over centennial and longer time scales across north-central Asia. Tree-ring width records have been extensively studied in Mongolia as proxies for climate reconstruction, however, the climate and environmental signals of tree-ring stable isotopes from this region need to be further explored. Here, we evaluated a 182-year record of tree-ring δ13C and δ18O from Siberian Pine (Pinus sibirica Du Tour) from a xeric site in central Mongolia (Khorgo Lava) to elucidate the environmental factors modulating these parameters. First, we analyzed the climate sensitivity of tree-ring δ13C and δ18O at Khorgo Lava for comparison with ring-width records, which have been instrumental in reconstructing hydroclimate in central Mongolia over two millennia. We also compared stable isotope records of trees with partial cambial dieback ('strip-bark morphology'), a feature of long-lived conifers growing on resource-limited sites, and trees with a full cambium ('whole-bark morphology'), to assess the inferred leaf-level physiological behavior of these trees. We found that interannual variability in tree-ring δ13C and δ18O reflected summer hydroclimatic variability, and captured recent, extreme drought conditions, thereby complementing ring-width records. The tree-ring δ18O records also had a spring temperature signal and thus expanded the window of climate information recorded by these trees. Over longer time scales, strip-bark trees had an increasing trend in ring-widths, δ13C (and intrinsic water-use efficiency, iWUE) and δ18O, relative to whole-bark trees. Our results suggest that increases in iWUE at this site might be related to a combination of leaf-level physiological responses to increasing atmospheric CO2, recent drought, and stem morphological changes. Our study underscores the potential of stable isotopes for broadening our understanding of past climate in north-central Asia. However, further studies are needed to understand how stem morphological changes might impact stable isotopic trends.

Global wood anatomical perspective on the onset of the Late Antique Little Ice Age (LALIA) in the mid-6th century CE.

Linked to major volcanic eruptions around 536 and 540 CE, the onset of the Late Antique Little Ice Age has been described as the coldest period of the past two millennia. The exact timing and spatial extent of this exceptional cold phase are, however, still under debate because of the limited resolution and geographical distribution of the available proxy archives. Here, we use 106 wood anatomical thin sections from 23 forest sites and 20 tree species in both hemispheres to search for cell-level fingerprints of ephemeral summer cooling between 530 and 550 CE. After cross-dating and double-staining, we identified 89 Blue Rings (lack of cell wall lignification), nine Frost Rings (cell deformation and collapse), and 93 Light Rings (reduced cell wall thickening) in the Northern Hemisphere. Our network reveals evidence for the strongest temperature depression between mid-July and early-August 536 CE across North America and Eurasia, whereas more localised cold spells occurred in the summers of 532, 540-43, and 548 CE. The lack of anatomical signatures in the austral trees suggests limited incursion of stratospheric volcanic aerosol into the Southern Hemisphere extra-tropics, that any forcing was mitigated by atmosphere-ocean dynamical responses and/or concentrated outside the growing season, or a combination of factors. Our findings demonstrate the advantage of wood anatomical investigations over traditional dendrochronological measurements, provide a benchmark for Earth system models, support cross-disciplinary studies into the entanglements of climate and history, and question the relevance of global climate averages.

Learners' Perspectives of Professionalism: Protocol for a Mixed Methods Systematic Review.

BACKGROUND: Professionalism has come to be associated with competence in medical education, with the habitual and judicious use of communication, knowledge, technical skills, clinical reasoning, emotions, values, and reflection in daily practice for the benefit of the individual and community being served. Recent studies indicate students should have the opportunity to observe the application of knowledge and skills by their mentors to improve patient health and safety. A noticeable detail that needs implementation into the curriculum is the inclusion of student perspectives. This review will explore students' understanding and experience of professionalism in undergraduate medical education (UME). OBJECTIVE: This paper presents the protocol for a review that aims to develop an integrated synthesis of qualitative and quantitative studies resulting in recommendations for medical school curricula to incorporate the learners' perspectives in teaching professionalism in UME. METHODS: We will take an integrated approach to synthesis. Data will be extracted from the included studies, and quantitative data will be "qualitized." PubMed (Medline), Embase, PsycInfo, and ERIC (Education Resources Information Center) will be searched for studies published in English from 2010 to 2021. Studies will be screened and critically appraised for methodological quality using the Mixed Methods Appraisal Tool by 2 researchers, with disagreements resolved by a third researcher. Qualitative, quantitative, and mixed methods studies will be considered. Our population of interest is undergraduate medical students; hence, studies on medical residents and graduate medical students will be excluded. We will consider studies that explore how concepts of professionalism are understood, experienced, and taught in undergraduate medicine and on how medical students understand and develop the identified constructs of professionalism. RESULTS: This study is in the screening phase; therefore, no results are available at this time. However, we had initiated the searches, screening, and are currently in the critical appraisal stage. We will commence preparation to clean and convert the data for coding in July 2022, and analysis will be ongoing from the end of July 2022 until submission for publication in November 2022. CONCLUSIONS: This research will contribute to the student perspectives on professionalism in medical education literature. The findings will aid in the creation of a checklist to guide the development of a curriculum on professionalism in UME. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): PRR1-10.2196/37473.

COVID-19 Vaccination and Intention to Vaccinate Among a Sample of College Students in New Jersey.

Vaccines are critical for curtailing the COVID-19 pandemic and may represent an important tool for return to "normalcy" on college campuses in the Fall of 2021. The purpose of this study was to investigate the extent of vaccination coverage and intention to vaccinate among college students. College students (N = 457) enrolled in the Spring 2021 semester at a university in New Jersey completed a cross-sectional survey. The survey collected information on demographics, COVID-19 and vaccination history, knowledge levels and sources of COVID-19 vaccine information, and vaccine attitudes. Multivariable regression analysis was performed to identify factors associated with vaccination, and the intention to vaccinate among non-vaccinated students. Results indicate that 23% (n = 105) of participants reported being vaccinated already. Among non-vaccinated students, 52.8% indicated their intention to receive the vaccine when it is made available to college students. Students who were health care workers (adjusted odds ratio, aOR = 4.17, p < 0.001), had a family member who had received a COVID-19 vaccine (aOR = 5.03, p < 0.001), exhibited greater positive attitudes regarding vaccination (aOR = 1.12, p < 0.001), and received a seasonal flu vaccine (aOR = 1.97, p < 0.05) were more likely to have received the COVID-19 vaccine. Among non-vaccinated students, those who discussed COVID-19 vaccine information with others (aOR = 5.38, p < 0.001), and exhibited more overall positive attitudes regarding vaccination (aOR = 2.69, p < 0.001), were more likely to indicate their willingness to receive the COVID-19 vaccine. Findings of this study highlight the need for additional education and vaccine outreach aimed at promoting uptake of the COVID-19 vaccine among college students.

The impact of the COVID-19 epidemic on mental health of undergraduate students in New Jersey, cross-sectional study.

OBJECTIVE: The COVID-19 pandemic has been a period of upheaval for college students. The objective of this study was to assess the factors associated with the increased levels of mental health burden among a sample of undergraduate college students in Northern New Jersey, the region of the U.S. severely impacted by the outbreak of COVID-19. METHODS: College students (N = 162) enrolled in an introductory core curriculum course completed a cross-sectional survey. The survey collected information on demographics, knowledge levels and sources of COVID-19 information, behavior changes, academic and everyday difficulties, and mental health measurements (depression, anxiety, somatization, and stress). Multivariable regression analysis was performed to identify factors associated with mental health outcomes. RESULTS: Descriptive findings indicate that students have a fundamental knowledge of COVID-19 transmission and common symptoms. Students tend to use and trust the official sources and have changed their behaviors in accordance with public health recommendations (i.e., increased hand washing, wearing mask). However, students reported a number of academic and everyday difficulties and high levels of mental health distress. High levels of depression were associated with difficulties in focusing on academic work and with employment losses, while higher levels of anxiety were more likely to be reported by students other than freshmen and those who spend more than one hour per day looking for information on COVID-19. Inability to focus on academic work and an elevated concern with COVID-19 were more likely to be associated with higher levels of somatization, while trusting news sources was associated with lower levels of somatization. Those with higher levels of perceived stress were more likely to be females, unable to focus on academic work, and report difficulties in obtaining medications and cleaning supplies. CONCLUSIONS: The COVID-19 pandemic is making a significant negative impact on mental health of college students. Proactive efforts to support the mental health and well-being of students are needed.

Author Correction: Tree rings reveal globally coherent signature of cosmogenic radiocarbon events in 774 and 993 CE.

The original version of this Article contained an error in the Data Availability section, which incorrectly read 'All data will be freely available via https://www.ams.ethz.ch/research.html .' The correct version states ' http://www.ams.ethz.ch/research/published-data.html ' in place of ' https://www.ams.ethz.ch/research.html '. This has been corrected in both the PDF and HTML versions of the Article.

Tree rings reveal globally coherent signature of cosmogenic radiocarbon events in 774 and 993 CE.

Though tree-ring chronologies are annually resolved, their dating has never been independently validated at the global scale. Moreover, it is unknown if atmospheric radiocarbon enrichment events of cosmogenic origin leave spatiotemporally consistent fingerprints. Here we measure the 14C content in 484 individual tree rings formed in the periods 770-780 and 990-1000 CE. Distinct 14C excursions starting in the boreal summer of 774 and the boreal spring of 993 ensure the precise dating of 44 tree-ring records from five continents. We also identify a meridional decline of 11-year mean atmospheric radiocarbon concentrations across both hemispheres. Corroborated by historical eye-witness accounts of red auroras, our results suggest a global exposure to strong solar proton radiation. To improve understanding of the return frequency and intensity of past cosmic events, which is particularly important for assessing the potential threat of space weather on our society, further annually resolved 14C measurements are needed.

Hydroclimate variations in central and monsoonal Asia over the past 700 years.

Hydroclimate variations since 1300 in central and monsoonal Asia and their interplay on interannual and interdecadal timescales are investigated using the tree-ring based Palmer Drought Severity Index (PDSI) reconstructions. Both the interannual and interdecadal variations in both regions are closely to the Pacific Decadal Oscillation (PDO). On interannual timescale, the most robust correlations are observed between PDO and hydroclimate in central Asia. Interannual hydroclimate variations in central Asia are more significant during the warm periods with high solar irradiance, which is likely due to the enhanced variability of the eastern tropical Pacific Ocean, the high-frequency component of PDO, during the warm periods. We observe that the periods with significant interdecadal hydroclimate changes in central Asia often correspond to periods without significant interdecadal variability in monsoonal Asia, particularly before the 19th century. The PDO-hydroclimate relationships appear to be bridged by the atmospheric circulation between central North Pacific Ocean and Tibetan Plateau, a key area of PDO. While, in some periods the atmospheric circulation between central North Pacific Ocean and monsoonal Asia may lead to significant interdecadal hydroclimate variations in monsoonal Asia.

An ensemble weighting approach for dendroclimatology: drought reconstructions for the northeastern Tibetan Plateau.

Traditional detrending methods assign equal mean value to all tree-ring series for chronology developments, despite that the mean annual growth changes in different time periods. We find that the strength of a tree-ring model can be improved by giving more weights to tree-ring series that have a stronger climate signal and less weight to series that have a weaker signal. We thus present an ensemble weighting method to mitigate these potential biases and to more accurately extract the climate signals in dendroclimatology studies. This new method has been used to develop the first annual precipitation reconstruction (previous August to current July) at the Songmingyan Mountain and to recalculate the tree-ring chronology from Shenge site in Dulan area in northeastern Tibetan Plateau (TP), a marginal area of Asian summer monsoon. The ensemble weighting method explains 31.7% of instrumental variance for the reconstructions at Songmingyan Mountain and 57.3% of the instrumental variance in the Dulan area, which are higher than those developed using traditional methods. We focus on the newly introduced reconstruction at Songmingyan Mountain, which showsextremely dry (wet) epochs from 1862-1874, 1914-1933 and 1991-1999 (1882-1905). These dry/wet epochs were also found in the marginal areas of summer monsoon and the Indian subcontinent, indicating the linkages between regional hydroclimate changes and the Indian summer monsoon.