From Craft to Nature: The Emergence of Natural Teleology

A teleological explanation is an explanation in terms of an end or a purpose. So saying that ‘X came about for the sake of Y’ is a teleological account of X. It is a striking feature of ancient Greek philosophy that many thinkers accepted that the world should be explained in this way. However, before Aristotle, teleological explanations of the cosmos were generally based on the idea that it had been created by a divine intelligence. If an intelligent power made the world, then it makes sense that it did so with a purpose in mind, so grasping this purpose will help us understand the world. This is the pattern of teleological explanation that we find in the Presocratics and in Plato. However, with Aristotle teleology underwent a change: instead of thinking that the ends were explanatory because a mind had sought to bring them about, Aristotle took the ends to operate in natural beings independently of the efforts of any creative intelligence. Indeed, he thought that his predecessors had failed to understand what was distinctive of nature, namely, that its ends work from the inside of natural beings themselves

Aristotle on the Matter for Birth, Life, and the Elements

This essay considers three case studies of Aristotle’s use of matter, drawn from three different scientific contexts: menstrual fluid as the matter of animal generation in the Generation of Animals, the living body as matter of an organism in Aristotle’s On the Soul (De Anima), and the matter of elemental transformation in Generation and Corruption. I argue that Aristotle conceives of matter differently in these treatises (1) because of the different sorts of changes under consideration, and (2) because sometimes he is considering the matter for one specific change, and sometimes the matter for all of a thing’s natural changes. My account allows me to explain some of the strange features that Aristotle ascribes to the matter for elemental transformation in Generation and Corruption II. These features were interpreted by later commentators as general features of all matter. I argue that they are a result of the specific way that Aristotle thinks about the transmutation of the elements

Should We Resect Hoffa's Fat Pad during Total Knee Replacement?

Resection of Hoffa's fat pad during total knee arthroplasty is sometimes performed to improve access and view. Opponents of this technique argue that sacrificing the fat pad potentially compromises blood supply to the patellar tendon and it can subsequently shorten. Our objective was to identify any difference in the Insall-Salvati ratio of knees undergoing total knee arthroplasty between a cohort that had Hoffa's fat pad preserved and the one that had Hoffa's fat pad completely excised. The total knee arthroplasties by two surgeons at our institution were reviewed over a 3-year period. Surgeon A routinely preserves the fat pad and surgeon B routinely excises the fat pad. Radiographs preoperatively, immediately postoperatively, and at a minimum of 1-year follow up were analyzed for the Insall-Salvati ratio. A total of 161 knees were reviewed, 65 in the preserved group and 96 in the excised group with a mean age of 67 and 70 years, respectively. The mean preoperative Insall-Salvati ratio for the preserved group was 1.12 (±0.145) and excised group 1.16 (±0.168) (p = 0.094). The mean immediate postoperative Insall-Salvati ratio for the preserved group was 1.10 (±0.154) and for excised group 1.18 (±0.194). The difference in Insall-Salvati ratio from preoperative to the immediate postoperative period in the preserved group compared with the excised group demonstrated a significant difference (p = 0.010). However, the change of Insall-Salvati ratio at 1 year did not significantly differ between the groups (p = 0.059). There does not appear to be any difference in the Insall-Salvati ratios of both groups at 1 year's follow up; therefore, this study radiologically at least supports the use of either technique

Proton NMR Relaxometry as a Rapid and Non-Destructive Technique for Probing Degradation of Supported Poly(ethylenimine) for CO2 Direct Air Capture

Aminopolymer-based adsorbents are commonly investigated for CO2 direct air capture (DAC). In the presence of high temperature and O2, which could happen during process upset, oxidative degradation can significantly contribute to limiting the adsorbent lifetime. Here, we demonstrate the use of a portable, benchtop NMR sensor to collect proton relaxometry profiles to track the degradation of a PEI/Al2O3 sample exposed to controlled accelerated oxidation conditions and correlate the extent of oxidation as measured by loss in amine efficiency with T2 (spin-spin) relaxation times. We hypothesize that T2 relaxation accurately tracks oxidative degradation in aminopolymers because of reduced polymer mobility resulting from radical-induced crosslinking that can occur during the oxidation process. The advantage of using NMR relaxometry as a non-destructive technique to probe degradation is demonstrated on a 1-inch square-channel monolith adsorbent exposed to actual DAC service conditions, highlighting the potential for using this technique as a rapid and non-destructive method of probing adsorbent health

What's a plant?

Ask yourself: what is a plant? You will probably answer that it is an organism able to photosynthesise chlorophyll. Depending on your level of knowledge in biology, your answer will be more or less elaborate. Now, ask a young child what a plant is, and their answer is likely to be very different. Their definition may centre on the notion of plant rootedness: a plant is something that is rooted to the ground and cannot move as a result

SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study

Background Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18-49, 50-69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. Conclusion As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population.The aim of this study was to inform vaccination prioritization by modelling the impact of vaccination on elective inpatient surgery. The study found that patients aged at least 70 years needing elective surgery should be prioritized alongside other high-risk groups during early vaccination programmes. Once vaccines are rolled out to younger populations, prioritizing surgical patients is advantageous