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Exact results, transient generalized Gibbs ensembles, and analytic approximations for spacetime propagators of massive, real scalar fields in one spatial dimension
No full textThe massive, real scalar field described by the Klein-Gordon equation in one spatial dimension is the most elementary example of a bosonic quantum field theory. It has been investigated for many decades either as a simple academic theory or as a realistic emergent many-body theory in low-dimensional systems. Despite this, the space and time behavior of its propagators have rarely been in the foreground, and although exact results are known, there remain gaps in the description and a lack of an in-depth physical analysis. The aim of this paper is to address the deficits by providing a comprehensive discussion of the results, and to show that this old theory still allows for several new results and insights. To start, we review the known results by providing a rederivation in full detail, to which we add a discussion on how exactly space and time variables need to be extended to complex values to ensure analyticity throughout spacetime. This procedure shows also how singularities on the lightcone need to be regularized to remain compatible with the analyticity and the physical limit of a vanishing mass. An extension to nonzero temperatures is provided by considering the contact of the field to a nonrelativistic thermal reservoir, such as is necessary for emerging field theories in condensed matter systems. Subsequently, it is shown that the transient, short spacetime propagation can be understood in the context of the modern development of a generalized Gibbs ensemble, which describes a massless theory with an effective temperature that is set by the Klein-Gordon mass and the physical temperature. Finally, an approximation scheme is presented that captures the non-trivial mass dependence of the propagators throughout all spacetime but involves only elementary functions
A simple [2 + 2] photocycloaddition reaction that proceeds in an NMR tube, illuminated by daylight
No full textThis work presents a simple and small-scale procedure that demonstrates the use of daylight to promote a photochemical [2 + 2] cycloaddition reaction. Previous related experimental protocols used in teaching laboratories have been focused on the preparation of “Cookson’s ketone” (pentacyclo-[5.4.0.02,6.03,10.05,9]undecane-8,11-dione). These approaches require an initial Diels–Alder reaction of cyclopentadiene and 1,4-benzoquinone, followed by an ultraviolet (UV) light-promoted intramolecular [2 + 2] cycloaddition reaction. This Laboratory Experiment highlights an alternative approach, where an analogue of Cookson’s ketone is readily prepared on a small scale from a stable diene and the photochemical [2 + 2] reaction proceeds in an NMR tube illuminated by daylight. The synthesis and NMR experiments described have been used in an advanced-level university laboratory course as an example of photochemical synthesis and use of 1D and 2D NMR spectroscopy to monitor reaction progress
Knowledge, inquiry and dogmatism
No full textThe popular idea that knowledge is the aim of inquiry appears to licence a specific form of dogmatism: once one knows the answer to a question, one ought to decline further evidence bearing on it. For, in knowing the answer to the question, one has already met the aim of inquiry. And by gathering further evidence one risks losing that knowledge by acquiring misleading evidence. After distinguishing the relevant form of dogmatism from standard dogmatism, I reject a range of different responses to this challenge including that gathering further evidence may answer alternative inquiries, the idea that the aim of inquiry is not knowledge but something stronger, or appeal to the personal aims of inquirers. Here I argue that none of these replies are adequate and instead suggest a solution that appeals to situation-sensitive epistemic norms on inquiry
The impact of the COVID-19 pandemic on antimicrobial usage:an international patient-level cohort study
No full textBackground: This study aimed to evaluate the trends in antimicrobial prescription during the first 1.5 years of COVID-19 pandemic.Methods: This was an observational, retrospective cohort study using patient-level data from Bangladesh, Brazil, India, Italy, Malawi, Nigeria, South Korea, Switzerland and Turkey from patients with pneumonia and/or acute respiratory distress syndrome and/or sepsis, regardless of COVID-19 positivity, who were admitted to critical care units or COVID-19 specialized wards. The changes of antimicrobial prescription between pre-pandemic and pandemic were estimated using logistic or linear regression. Pandemic effects on month-wise antimicrobial usage were evaluated using interrupted time series analyses (ITSAs).Results: Antimicrobials for which prescriptions significantly increased during the pandemic were as follows: meropenem in Bangladesh (95% CI: 1.94-4.07) with increased prescribed daily dose (PDD) (95% CI: 1.17-1.58) and Turkey (95% CI: 1.09-1.58), moxifloxacin in Bangladesh (95% CI: 4.11-11.87) with increased days of therapy (DOT) (95% CI: 1.14-2.56), piperacillin/tazobactam in Italy (95% CI: 1.07-1.48) with increased DOT (95% CI: 1.01-1.25) and PDD (95% CI: 1.05-1.21) and azithromycin in Bangladesh (95% CI: 3.36-21.77) and Brazil (95% CI: 2.33-8.42). ITSA showed a significant drop in azithromycin usage in India (95% CI: -8.38 to -3.49 g/100 patients) and South Korea (95% CI: -2.83 to -1.89 g/100 patients) after WHO guidelines v1 release and increased meropenem usage (95% CI: 93.40-126.48 g/100 patients) and moxifloxacin (95% CI: 5.40-13.98 g/100 patients) in Bangladesh and sulfamethoxazole/trimethoprim in India (95% CI: 0.92-9.32 g/100 patients) following the Delta variant emergence.Conclusions: This study reinforces the importance of developing antimicrobial stewardship in the clinical settings during inter-pandemic periods.</p
In situ generation by cyclization of an organic structure directing agent for the synthesis of high silica zeolite ERS-7
No full textZeolites with high framework Si/Al ratios are of interest for industrial applications due to their hydrothermal stability. They are usually synthesized in the presence of pre-prepared organic structure directing agents (OSDAs). The high silica ERS-7 zeolite (topology type ESV) can be crystallized using N,N-dimethylpyrrolidinium (dmpyrr) that is formed in situ via cyclization of N,N,N’,N’-tetramethyl-1,4-diaminobutane (tmdab) when a cationic polymer is also present. The in situ generation of dmpyrr is demonstrated by solid-state 13C NMR spectroscopy and supported by both chemical analyses and comparative syntheses using pre-prepared dmpyrr. The cationic polymer inhibits the crystallization of mordenite, which is otherwise observed to be the favored product. The ERS-7 prepared via in situ dmpyrr synthesis (Si/Al = 14) is characterized by PXRD and solid-state NMR spectroscopy. The CO2 adsorption seen for the H- and Na-forms indicates interactions with accessible Na+ cations. The synthetic studies indicate the potential for in situ generation of OSDAs to reduce the need for extended OSDA syntheses
Historical anchored (Type A) tags were associated with negative effects on North Atlantic right whale survival and reproduction
No full textTagging data can provide critical information to support the conservation of marine mammal species, but these benefits must be balanced against any potential adverse effects on the health and vital rates of tagged individuals, particularly in endangered populations. Data from historical tag deployments can be used to evaluate these effects. Here, we expand a model for the Population Consequences of Multiple Stressors to investigate the effects of invasive tags deployed from the late 1980s through 2001 on the health, survival and reproduction of critically endangered North Atlantic right whales (Eubalaena glacialis). Historical tags deployed on this species include anchored (Type A) tags and consolidated (Type C) tags. The effects of these deployments were explored alongside the effects of other stressors included in the model (entanglements, vessel strikes and prey abundance). Our results indicate that historical anchored (Type A) tags had a negative effect on the health of tagged individuals, which is linked in the model with their survival and calving probabilities. We found limited evidence in additional exploratory analyses that confounding factors may have affected our findings. In contrast, we did not detect any effect of historical consolidated (Type C) tags. This study demonstrates the utility of our modelling approach for assessing the effects of invasive tagging on the survival and reproduction of tagged individuals. The model could be used to explore the effects of future deployments on this critically endangered species, contributing to improve tag design and inform future permitting decisions
Anselm on THAT, THIS, and panpsychism
No full textThis articles reimagines Anselm’s claim that God is ‘that than which a greater cannot be thought’ [Hereafter: ‘THAT’]. The article first explores a variety of Anselm-inspired of what THAT is like, and how THAT relates to whatever (if anything) is not-THAT (hereafter: ‘THIS’). THAT could be Anselm’s creator God, a polytheist pantheon, or a single undifferentiated One/Absolute/Brahman. THIS could be a single possible world or a pluriverse containing many different real possible worlds. The article defends a principle of cosmic humility. It argues that, to counter our natural tendency to over-estimate our own importance, we should pay particular attention to non-human-centred, non-anthropomorphic interpretations of THAT. Humility favours plenitude about worlds and plenitude about creatures. God (or THAT) will create many worlds that (together) contain all valuable creatures. Humility also suggests that, within this optimal pluriverse, we should not expect to find ourselves inhabiting either a world that is cosmically special or a world where we are special. The final part of the article argues that, within contemporary philosophy of mind, this commitment to cosmic humility supports panpsychism over its rivals – especially dualism and materialism. If THAT did create THIS, then we are (probably) insignificant creatures living in a panpsychist world. The article concludes with some speculations on how thinking about THAT and THIS might also influence the content of panpsychism as well as the case for panpsychism
Contrasting drivers of consecutive pre-monsoon South Asian heatwaves in 2022:waveguide interaction and soil moisture depletion
No full textSouth Asian countries including India, Pakistan, and Afghanistan experienced consecutive heatwave episodes in 2022, with the first episode in March, followed by an equally intense event in April of the same year. Here, we use diagnostics of local wave activity, waveguidability, and soil moisture-temperature coupling to gain insights into the previously underexplored dynamic and land drivers underlying these early pre-monsoon heatwave episodes. Our findings reveal a sudden surge in wave activity in the upper troposphere over the heatwave region during the first episode of the heatwave. The intensified wave activity results from strong transient waves, due to transfer of energy from the extratropical to the subtropical waveguide, leading to strong anticyclonic circulation. The April heatwave event, in contrast to the first episode, is found to be the result of a strong soil moisture-temperature coupling over the heatwave region. Further, the low-level winds revealed an advection of heat from highly coupled regions (Pakistan and Afghanistan) to the Indian landmass during the heatwave episode in April. Our findings indicate that waveguide interaction together with equatorward energy transfer drives early heat in March, subsequently setting the stage for further heat in the following weeks by depleting soil moisture levels
Shifting patterns of mobility in the Insular Scandinavian diaspora between the ninth and eleventh centuries
No full textIn Insular history, the period from around 800 to 1300 was characterised by a series of increased interactions with Scandinavia, extending from the first recorded viking raids in the late ninth century down to the diplomatic relations between the kings of Norway, England and Scotland in the thirteenth and fourteenth centuries. This paper combines prosopographical and material approaches to explore the shifting patterns of mobility of members of the Scandinavian diaspora principally associated with Ireland and Britain across several centuries of this socially and materially entangled era. The principal portion of the paper is concerned with the mobility of three individuals: Óláfr of Hlaðir (ob.AD873×878), Óláfr Cúarán Sigtryggsson (ob.AD980×981), and Echmarcach Rǫgnvaldsson (ob.AD1064). A full, high-resolution discussion of the evidence for each individual is not possible within the confines of this article, but will be found in a series of pieces related to each figure currently either under review or in preparation
Simultaneous “fix and replace” has non inferior survivorship compared to staged arthroplasty in acetabular fracture management at two year follow up
No full textAims: In an increasingly frail population, simultaneous “fix and replace” surgery (fixation of the acetabulum to accommodate a press fit cup and total hip arthroplasty (THA)) is a novel alternative to open reduction and internal fixation (ORIF) alone in the management of acetabular fractures. We aimed to determine whether patients managed with “fix and replace” have comparable survivorship to those undergoing staged THA following previous open reduction and internal fixation for acetabular fracture.Methods: All Patients with acetabular fractures surgically managed within our Tertiary centre over a five year period (01/01/2018–30/05/2023) were identified. Thirty-four patients underwent simultaneous “fix and replace” surgery and 133 underwent acetabular ORIF alone. Twenty-one of these patients required staged THA (6 %).Results: Follow up mean was 2.7 years (SD ±1.7) for 'fix and replace' versus 3.3 years (SD ± 1.5) for staged THA. There was no statistically significant difference between the two groups with regards to BMI or sex. The fix and replace group were older (p = 0.001), had higher American Society of Anesthesiologists (ASA) grade (p = 0.006) and Charlson Comorbidity Index (CCI) (p = 0.027), respectively. High energy mechanism of injury accounted for 56 % of the "fix and replace" group compared to 48 % in the ORIF to THA. 74 % of 'fix and replace' were associated/complex fractures (LeTournel) compared to 53 % of staged THA. Mean wait to surgery was 3 days in the 'fix and replace' group compared to 186 days from listing to operation in the staged THA group. Survival analysis demonstrated acceptable results for both groups with greater than 85 % survival at 2 years and no statistical significantly worse survivorship in the 'fix and replace' group (p = 0.13). Complications were comparable in both groups (41 % versus 43 %, p = 0.58).Conclusions: 'Fix and replace' is a good option for the elderly, co-morbid patient. It enables early weight bearing and has acceptable survivorship compared to staged THA following acetabular ORIF