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Constraining the timing, forcing, and climate impacts of volcanic eruptions during the Common Era and beyond
No full textVolcanic eruptions can have climatic and societal impacts which, for major eruptions, may persist for several years after the event. Consequently, they are considered a key natural forcer in the climate system and reconstructions of volcanic forcing are an important input into climate models used for future climate forecasting and policy decision making. Generating a robust record of past global volcanic eruptions is therefore essential, with the polar ice-core records a key archive in this process. However, eruption records are incomplete across the last 2000 years. This thesis presents a multi-proxy toolkit comprising of cryptotephra, sulfur isotopes, and novel glaciochemical tracers, which, when applied to ice-core records from Greenland and Antarctica, allowed the timing and forcing of volcanic eruptions during the Common Era to be constrained. Using this toolkit, smaller and prolonged volcanic events, currently absent from existing forcing reconstructions, were identified and attributed to their sources. In addition, existing mismatches were resolved within the Antarctic records, enabling a revision of volcanic stratospheric sulfur injection estimates during the 17th century. Having constrained eruption parameters (timing, quantity of sulfur injected, provenance, and altitude of injection), a network of paleo-proxy records were employed to explore the climate impacts associated with selected events. This revealed the pronounced northern hemisphere climate impacts following northern hemisphere extratropical eruptions. Alongside ice core derived eruption parameters and petrological estimates, paleo-proxy records were also used to generate eruption emission scenarios for selected Icelandic events, thereby assisting in reconciling existing offsets with model outputs. Ultimately, through the adoption of this multi-proxy toolkit and an interdisciplinary approach, this thesis has constrained the eruption parameters for several volcanic events and explored their climate impacts. This has contributed to improving existing global records of past volcanic eruptions and forcing reconstructions during the Common Era
The association between medication use and health-related quality of life in multimorbid older patients with polypharmacy.
Get PDFPURPOSE
To explore the association between medication use-related factors and health-related quality of life (HRQoL) in older hospitalised multimorbid patients with polypharmacy.
METHODS
This cross-sectional study used the intervention arm data of the OPERAM trial (hospitalised patients ≥ 70 years with polypharmacy). HRQoL was assessed using the visual analogue scale (EQ-VAS) and the EQ-5D index score of the EuroQol questionnaire (EQ-5D-5L). Lower or higher EQ-VAS/EQ-5D was based on the median of the study population. Medication use-related factors included hyperpolypharmacy (≥ 10 medications), anticholinergic and sedative burden, appropriateness of medication (STOPP/START criteria), high-risk medication for hospital (re)admission, medication complexity and adherence. Multivariable logistic regression analysis was used to assess the association between medication use-related factors and HRQoL.
RESULTS
A total of 955 patients were included (mean age 79 years, 46% female, median EQ-VAS of 60, median EQ-5D of 0.60). Opioids use was associated with lower EQ-5D and EQ-VAS (aOR EQ-5D: 2.10; 95% CI 1.34-3.32, EQ-VAS: 1.59; 1.11-2.30). Hyperpolypharmacy (aOR 1.37; 1.05-1.80), antibiotics (aOR 1.64; 1.01-2.68) and high medication complexity (aOR 1.53; 1.10-2.15) were associated with lower EQ-VAS. A high anticholinergic and sedative burden (aOR 1.73; 1.11-2.69), presence of multiple prescribing omissions (aOR 1.94; 1.19-3.17) and benzodiazepine use (aOR 2.01; 1.22-3.35) were associated with lower EQ-5D. Especially in hyperpolypharmacy patients, high anticholinergic and sedative burden and medication complexity were associated with a lower HRQoL.
CONCLUSION
Several medication use-related factors are significantly associated with a lower HRQoL in hospitalised older patients. Medication complexity is a novel factor, which should be considered when evaluating medication use of older patients with hyperpolypharmacy
Dispensability of HPF1 for cellular removal of DNA single-strand breaks.
Get PDFIn response to DNA damage, the histone PARylation factor 1 (HPF1) regulates PARP1/2 activity, facilitating serine ADP-ribosylation of chromatin-associated factors. While PARP1/2 are known for their role in DNA single-strand break repair (SSBR), the significance of HPF1 in this process remains unclear. Here, we investigated the impact of HPF1 deficiency on cellular survival and SSBR following exposure to various genotoxins. We found that HPF1 loss did not generally increase cellular sensitivity to agents that typically induce DNA single-strand breaks (SSBs) repaired by PARP1. SSBR kinetics in HPF1-deficient cells were largely unaffected, though its absence partially influenced the accumulation of SSB intermediates after exposure to specific genotoxins in certain cell lines, likely due to altered ADP-ribosylation of chromatin. Despite reduced serine mono-ADP-ribosylation, HPF1-deficient cells maintained robust poly-ADP-ribosylation at SSB sites, possibly reflecting PARP1 auto-poly-ADP-ribosylation at non-serine residues. Notably, poly-ADP-ribose chains were sufficient to recruit the DNA repair factor XRCC1, which may explain the relatively normal SSBR capacity in HPF1-deficient cells. These findings suggest that HPF1 and histone serine ADP-ribosylation are largely dispensable for PARP1-dependent SSBR in response to genotoxic stress, highlighting the complexity of mechanisms that maintain genomic stability and chromatin remodeling
Migratory-derived resources induce elongated food chains through middle-up food web effects.
Get PDFBACKGROUND
Seasonal movements of animals often result in the transfer of large amounts of energy and nutrients across ecosystem boundaries, which may have large consequences on local food webs through various pathways. While this is known for both terrestrial- and aquatic organisms, quantitative estimates on its effects on food web structure and identification of key pathways are scarce, due to the difficulty in obtaining replication on ecosystem level with negative control, i.e. comparable systems without migration.
METHODS
In this study, we estimate the impact of Arctic charr (Salvelinus alpinus) migration on riverine ecosystem structure, by comparing multiple streams with strictly resident populations above natural migration barriers with streams below those barriers harboring partially migratory populations. We compared density estimates and size structure between above and below populations. Diet differences were examined through the analysis of stomach contents, changes in trophic position were examined by using stable isotopes. To infer growth rate of resident individuals, back-growth calculation was performed using otoliths.
RESULTS
We find higher densities of small juveniles in partially migratory populations, where juvenile Arctic charr show initially lower growth, likely due to higher intraspecific competition. After reaching a size, where they can start feeding on eggs and smaller juveniles, which are both more frequent in partially migratory populations, growth surpasses that of resident populations. Cannibalism induced by high juvenile densities occurred almost exclusively in populations with migration and represents an altered energy pathway to the food web. The presence of large cannibalistic charr feeding on smaller ones that have a similar trophic level as charr from strictly resident populations (based on stomach content) coupled with steeper δ15N-size regression slopes illustrate the general increase of food chain length in systems with migration.
CONCLUSIONS
Our results thus suggest that the consumption of migration-derived resources may result in longer food chains through middle-up rather than bottom-up effects. Furthermore, by occupying the apex of the food chain and feeding on juvenile conspecifics, resident individuals experience reduced competition with their young counterparts, which potentially balances their fitness with migratory individuals
Sulfate concentration and sulfur isotope data from Greenland TUNU2013 ice-core samples between 740-765 CE
No full textSulfate concentration and triple sulfur isotope (32S, 33S, 34S) data measured in TUNU2013 ice-core samples and calculated background-corrected isotope composition (Gabriel et al., in review). S-isotope analyses were made on 65 discrete samples (cross-sections of 6 cm2) cut from archived ice-core sections from TUNU2013, including prior background and full acid deposition lasting over 12 years. The sample resolution over the entire acid deposition event is 3 cm corresponding to a nominal 3-to-4-month age resolution. Sulfate concentration was measured by ion chromatography on the discrete samples, and the sulfate was purified from the melted ice using anion exchange columns. Triple sulfur isotopes (32S, 33S, and 34S) were measured on the samples using a Neptune Plus multi-collector inductively-coupled mass spectrometer (MC-ICP-MS) at the St Andrews Isotope Geochemistry Lab (STAiG lab) (Burke et al., 2019; Burke et al., 2023) and are reported as δ34S and D33S relative to Vienna-Canyon Diablo Troilite (V-CDT), where δxS =(xS/32S)sample/(xS/32S)V-CDT−1. A sample is considered to have a mass-independent fractionation signature if it has a nonzero value of D33S = δ33S -((δ34S + 1)^0.515 − 1), outside of 2σ uncertainty. Full procedural blanks and an in-house secondary standard (Switzer Falls) were processed alongside samples. All data was blank corrected for the process blanks, and uncertainties were propagated with Monte Carlo simulations. The isotopic composition of the volcanic sulfate (δ34Svolc and D33Svolc) was calculated using isotope mass balance and the concentration and isotopic composition of background ice from TUNU2013 taken prior and after the volcanic peaks in sulfate. Data is shown on the NS1-2011 chronology (Sigl et al., 2015). Isotopic composition of the volcanic sulfate is only provided for samples with more than 65% volcanic sulfate following Burke et al. (2019)
Streamlining malaria prevention recommendations for travellers: current and future approaches.
No full textDual role of BdMUTE during stomatal development in the model grass Brachypodium distachyon.
Get PDFGrasses form morphologically derived, four-celled stomata, where two dumbbell-shaped guard cells (GCs) are flanked by two lateral subsidiary cells (SCs). This innovative form enables rapid opening and closing kinetics and efficient plant-atmosphere gas exchange. The mobile bHLH transcription factor MUTE is required for SC formation in grasses. Yet, if and how MUTE also regulates GC development and if MUTE mobility is required for SC recruitment is unclear. Here, we transgenically impaired BdMUTE mobility from GC to SC precursors in the emerging model grass Brachypodium distachyon. Our data indicates that reduced BdMUTE mobility severely affected the spatiotemporal coordination of GC and SC development. Furthermore, while BdMUTE has a cell-autonomous role in GC division orientation, complete dumbbell morphogenesis of GCs required SC recruitment. Finally, leaf-level gas exchange measurements showed that dosage-dependent complementation of the four-celled grass morphology was mirrored in a gradual physiological complementation of stomatal kinetics. Together, our work revealed a dual role of grass MUTE in regulating GC division orientation and SC recruitment, which in turn was required for GC morphogenesis and the rapid kinetics of grass stomata
[Can we learn to die?].
No full textThe topic of death and the dying is a crucial aspect of patient care, especially for individuals with terminal illnesses. However, discussions about death and dying are often avoided during patient interactions. In this article, our aim is to explore the reasons behind our fear of death and dying and to assess the importance of addressing these issues in shaping and cultivating relationships with our patients and in our personal lives. We argue that being open to impermanence is a valuable tool in our work with patients and their families and should be integrated into conversations with them. Furthermore, discussions about death and dying should play a central role in medical and nursing education as well as professional development
Effect of preparation design on the fracture resistance and fracture patterns of 3D printed one-piece endodontic crowns.
No full textSTATEMENT OF PROBLEM
The impact of various preparation designs on the fracture resistance and fracture type of mandibular premolars restored with 3 dimensionally (3D) printed, 1-piece endodontic crowns remains unclear.
PURPOSE
The purpose of this study was to investigate the effect of different preparation designs on the fracture resistance and fracture patterns of mandibular premolars restored with 3D printed 1-piece endodontic crowns after thermal aging.
MATERIAL AND METHODS
Forty-five freshly extracted mandibular premolars received 3 different preparation designs: with at least 2 intact cuspal walls (2CW), with only 1 intact cuspal wall (1CW), and no cuspal wall present (NoCW). One-piece endodontic crowns were designed by using a computer-aided design (CAD) software program, 3D printed, cemented to the prepared teeth with self-adhesive resin cement, and thermocycled between 5 °C and 55 °C in artificial saliva. Subsequently, all specimens were subjected to a fracture test. The results were statistically analyzed using 1-way ANOVA (α=.05), and fracture types of all specimens were examined using a light microscope.
RESULTS
The analysis of fracture resistance values across separate designs revealed no statistically significant differences (P>.05). Mean fracture resistance values were 724.5 N in 2CW, 713 N in 1CW, and 861 N in NoCW. In 2CW and 1CW, the 1-piece endodontic crowns mostly displayed Type III fractures, whereas those in NoCW exhibited a combination of Type II and Type III fractures.
CONCLUSIONS
The mandibular premolar 1-piece endodontic crowns tested in this study exhibited similar fracture resistance and type of fracture with different preparation designs
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