Aims Mycophenolic acid (MPA) is typically used for anti-neutrophilic cytoplasmic antibody associated nephritis (AAN) but with large individual variability of pharmacokinetics. This study aims to investigate clinical factors impacting MPA disposal so as to simulate dosage regimen in pediatric AAN. Methods We conducted a retrospective study in 25 children with AAN treated with MPA. A population pharmacokinetic model was developed to explore the effects of demographics and biochemical covariates on MPA. Monte Carlo simulations were performed to optimize dosage regimens. Results A total of 391 MPA concentrations from 25 patients were analyzed. MPA pharmacokinetics best fitted a two-compartment model with first-order absorption and linear elimination. The pharmacokinetic parameters for Ka, CL, Vc, Vp, and Q were 0.45 h-1, 9.86 L/h, 19.69 L, 408.32 L and 23.01 L/h, respectively. Dosage form significantly affected drug absorption. CL significantly decreased with increasing cystatin C, while with decreasing myeloperoxidase. Cystatin C was superior to serum creatinine in predicting CL of MPA. A dose of 650 mg/m2 was required to achieve the target exposure in children with normal renal function and no inflammation. Dose of MPA in patients with renal failure was almost 1/3 that of normal kidney function. The combined effects of myeloperoxidase and renal function resulted in a 6-fold range in MPA dose. Conclusions Myeloperoxidase was not only a biomarker of AAN, but also an inflammatory factor to impact drug CL. The influence of renal function and underlying diseases on drug metabolism should be fully considered in personalized medication for AAN children.

Effective knowledge exchange between farmers and other stakeholders, such as agricultural extensionists and soil scientists, is essential for increasing opportunities for sustainable soil fertility management. To achieve this, it is necessary to understand local farmers' conceptualisation of soil fertility. This study visualizes farmers' perceptions of soil fertility as mental models, in order to explore the expansion of their soil knowledge and the extent of their comprehension of the relationship between soil properties that are seen and measured and soil processes. Aggregated mental models of fertile and low fertility soils were created from data collected from 59 farmer interviews at two villages in Kitui County, Kenya. The share of respondents of each concept were shown to analyse the knowledge gaps among farmers and between villages. The mental models revealed that farmers recognize the important roles of soil texture, water availability and farm management in soil fertility. Their knowledge related to their lived experience of the actual productivity of soils, which resulted in a strongly different perspective of fertile and low fertility soil. The differences of perception between the villages were also recognized as the result of differences in land availability. Although the farmers who mentioned soil processes were very few, farmers had the potential to integrate further soil scientific knowledge. Consequently, using the mental model approach to visualize farmers' perceptions produced benefits by clarifying understanding of farmers' knowledge and identifying gaps where soil science and extension work could help to expand farmers' knowledge.

In case of valvular infective endocarditis, the infection is mainly localized on the flow side of the valves or at damaged valvular endothelium. We describe a rare case of an aortic valvular inefctive endocarditis with an aortic-valve vegetation situated on the aortic side of the valve. We believe this is the first description of this unusual localization of vegetations in a native aortic valve.

Abstract Background: The aim of this study was to evaluate the potential effect of 6-minute walking distance (6MWD) on exercise tolerance in patients with pulmonary hypertension (PH). To clarify whether 6WMD and right ventricle (RV) function measured by three-dimensional echocardiography (3D-echo) could result in better correlation with exercise capacity. Methods: 72 consecutive patients underwent right heart catheterization (RHC) and diagnosed with PH. Associations between 6WMD and measures of RV function were evaluated using the Pearson correlation coefficient. Receiver operating characteristic (ROC) curve analysis was applied to evaluate the clinical prognosis of patients. Results: RHC-derived parameters were significantly correlated with 6MWD: (RPVR = -0.719, RPAPs = -0.501, RPAPd = -0.404, and RPAPm = -0.468, all P <0.001). Meanwhile, 6MWD was positively correlated with CO (R = 0.54, P <0.001). Good correlations between 6MWD with 3D-echo parameters were shown as follows: R3D-RVEDV = -0.584, R3D-RVESV = -0.598, R3D-RVEF = 0.554, R3D-RV mass = -0.507, all P <0.001. The predictive value from 6MWD was not much inferior to the predictive values of PVR (AUC6MWD = 0.779 vs. AUCPVR = 0.875, both P <0.0001). Conclusions: 6MWD has a significant correlation with hemodynamic parameters obtained by RHC. And RV function obtained by 3D-echo result in better correlation with exercise capacity. 3D-echo might be candidate for RHC to assess right heart function in patients with PH.

Plants transitioned from an aquatic to a terrestrial lifestyle during their evolution. On land, fluctuations on water availability in the environment became one of the major problems they encountered. The appearance of morpho-physiological adaptations to cope with and tolerate water loss from the cells was undeniably useful to survive on dry land. Some of these adaptations, such as carbon concentrating mechanisms (CCMs), desiccation tolerance (DT) and root impermeabilization, appeared in multiple plant lineages. Despite being crucial for evolution on land, it has been unclear how these adaptations convergently evolved in the various plant lineages. Recent advances on whole genome and transcriptome sequencing are revealing that co-option of genes and gene regulatory networks (GRNs) is a common feature underlying the convergent evolution of these adaptations. In this review we address how the study of CCMs and DT have provided insight into convergent evolution of GRNs underlying plant adaptation to dry environments, and how these insights could be applied to currently emerging understanding of evolution of root impermeabilization through different barrier cell types. We discuss examples of co-option, conservation, and innovation of genes and GRNs at the cell, tissue and organ levels revealed by recent phylogenomic (comparative genomic) and comparative transcriptomic studies.

In this study, it was investigated to increase the lipid yield of the microalgae Schizochytrium sp., by applying different cell disruption methods. Therefore, acid treatment with HCl, osmotic shock, enzyme applications and ultrasonic homogenizer were tried in this algae species combined with the Bligh and Dyer and Soxhlet methods as an alternative to classical lipid extraction methods. As a result of the study, the highest lipid value (21.72 ± 0.74%) was obtained in enzyme application with Bligh and Dyer method (BDE). The cell disruption processes increased the lipid yield compared to the control groups. The highest PUFA DHA was found in the range of 4.58 ± 2.44-19.25 ± 0.09%, and the highest value was observed in the BDE group. Highest SFA was palmitic acid. Effective results were observed in the Bligh and Dyer applied groups in terms of both total lipid and total fatty acids. In cell disruption methods, particularly in enzyme and HCl extraction, good results were obtained in terms of fatty acids. The highest total fatty acids and the highest lipid content were detected in the Bligh and Dyer enzyme (BDE). Enzyme applications are also advantageous because of being environmentally friendly. Lipid health indices such as n-6/n-3, PUFA/SFA, Atherogenicity index (AI), Thrombogenicity index (TI) and hypocholesterolemic/hypercholesterolemic ratios (HH) were almost favorable. With this study, an appropriate lipid extraction methods were determined to provide an economical and environmental friendly suggestion for future studies to be used in areas such as food, feed and cosmetics.

Abstract Objectives: This study aimed to evaluate the clinical utility of serum leukocyte counts (SLCs) for initial antibiotic use in Chinese women with mastitis who presented to the emergency department. Materials and Methods: Electronic medical records of breastfeeding women with mastitis were reviewed. Patients were divided into two groups according to the level of SLCs: slight elevated leukocyte counts (SELC, 1.0-1.5*10^9 cells/L); marked elevated leukocyte counts (MELC, >1.5*10^9 cells/L ). Treatment outcomes including rates of treatment failure and breast abscess formation were compared. Results: The rates of treatment failure and breast abscess were 12.7% and 7.1% in overall population and 7.7% and 6.4% in MELC group, respectively. In SELC group, treatment failures were observed in 29.7% and 6.4% patients without or with antibiotics, and the difference was significant (OR=4.207, 95% CI 1.318- 13.424); breast abscess was observed in 12.5% and 2.1% patients, and the difference was not significant (OR=6.571, 95% CI 0.793-54.481). Mean time to normal appearance of the breast or normal temperature was shorter in patients with antibiotics (3.8 ± 1.7 and 4.3 ± 2.1 days) than in patients without antibiotic use (2.5 ± 1.1 and 3.0 ± 1.3 days), p<0.001. Conclusion: Our study found that there were better clinical outcomes in patients with SELC or MELC when antibiotic was initially administrated compared to those without antibiotics, whicha indicates that SLC is an easy and practical reference index for gudiing antibiotic use, and patients who have an elevated SLC should be treated with antibiotic. Key Words: mastitis, antibiotic, serum leukocyte count

Introduction: Global medical advances within healthcare have subsequently led to the widespread introduction of biological products such as grafts, haemostats, and sealants. Although these products have been used for many decades, this subject is frequently not discussed during the consent process and remains an area of contention. Methods: A nationwide confidential online survey was distributed to UK-based junior registrars (ST3-5), senior registrars (ST6-8), post-CCT fellows, specialist associates/staff grade doctors and consultants working in general/vascular surgery, neurosurgery, otolaryngology, oral & maxillofacial surgery and plastic surgery. Results: Data was collected from a total of 308 survey respondents. Biological derivatives were correctly identified in surgical products by only 25% of survey respondents, only 19% stated that they regularly consent for use of these products. Our results demonstrate that most participants in this study do not routinely consent (81%) to the intra-operative use of biological materials. An overwhelming 74% of participants agreed that further education on the intra-operative use of biological materials would be valuable. Discussion: This study highlights deficiencies in knowledge that results in potential ethical compromise of the consenting process for surgical procedures. A solution to this would be for clinicians to increase their awareness via educational platforms and to incorporate an additional statement on the consent form which addresses the potential intraoperative use of biological products and what their derivatives may be. Conclusion: Modernising the current consent process to reflect the development and use of surgical biological products will help to ensure improved patient satisfaction, fewer future legal implications as well as a better surgeon-patient relationship.

1 Vegetation attributes derived from species and plant functional types (PFTs) directly or indirectly drive the carbon (C) cycle in peatlands. However, anthropogenic-based disturbances may alter petland soil-plant interactions and their ability to sequester carbon. Likewise, it is unclear how the soil-plant linkages among different soil C decomposition-based pools and plant attributes vary under disturbance conditions. 2 We aimed to assess how anthropogenic disturbances affect the relationships between aboveground vegetation attributes and belowground C pools in a peatland located in Northern Patagonia, Chile. We further evaluated if attributes derived from PFTs are better suited to predict soil C pools than attributes derived from species. We used structural equation modeling and regression analyses to explore these differences. 3 We found that undisturbed peatland has more soil-plant significant relationships between soil C pools and vegetation attributes, yielding higher predictive accuracies than disturbed areas. The species-based attributes yielded consistently better results predicting soil C pools than PFT-based attributes. However, PFT-based information showed significant interactions with the highly-decomposed C pools in the undisturbed peatland. Likewise, plant height and diversity were only significant with C pools in the undisturbed peatland. 4 We observed that water-logged plant communities have different soil-plant interactions than dryer communities. These differences were observed in both areas but were higher in the disturbed peatland, making it impossible to find meaningful soil-plant relationships across vegetation types and taxa. 5 Our results highlight the importance of accounting for disturbance or management when linking vegetation attributes to soil C pools in peatlands. This implies that up-to-date extensive monitoring of peatland disturbances is needed to accurately monitor soil C attributes at the regional level using vegetation as proxies. We also need to aggregate species into specific plant functional types that hold these soil-plant interactions across landscapes, regions, and disturbances to generalize the soil-plant relationships accurately.

The decline of coral reefs has fueled interest in determining whether mesophotic reefs can shield against disturbances and help replenish deteriorated shallower reefs. In this study, we characterized spatial (horizontal and vertical) and seasonal patterns of diversity in coral recruits from Dabaisha and Guiwan reefs at Ludao, Taiwan. Concrete blocks supporting terra cotta tiles were placed at shallow (15m) and mesophotic (40m) depths, during 2016-2018. Half of the tiles were retrieved and replaced biannually over three 6-month surveys (short-term); the remainder retrieved at the end of the 18-month (long-term) survey. 451 recruits were located using fluorescent censusing and identified by DNA barcoding. Barcoding the mitochondrial cytochrome oxidase I (COI) gene resulted in 17 molecular operational taxonomic units (MOTUs). To obtain taxonomic resolution beyond the generic level, Pocillopora were phylotyped using the mitochondrial open reading frame (ORF), resolving eight MOTUs. Acropora, Isopora or Montipora recruits were identified by the nuclear PaxC intron, yielding ten MOTUs. Overall, 35 MOTUs were generated and were comprised primarily of Pocillopora, and in fewer numbers, Acropora, Isopora, Pavona, Montipora, Stylophora, among others. 40% of MOTUs recruited solely within mesophotic reefs while 20% were shared by both depth zones. MOTUs recruiting across a broad depth distribution appear consistent with the hypothesis of mesophotic reefs acting as a refuge for shallow water coral reefs. In contrast, Acropora and Isopora MOTUs were structured across depth zones representing an exception to this hypothesis. This research provides an imperative assessment of coral recruitment in understudied mesophotic reefs and imparts insight into the refuge hypothesis.

In this article, we report a 34-year-old man who presented with progressive hip pain and osteolytic bone lesions . Primary workup included Core needle biopsies manifested as osteomyelitis; however as no sign of remission was observed, an open biopsy considered which revealed primary bone lymphoma.

Colony is the basic geometric construction of coral reef. However, both the forming regulations of colony and reef are still obscure. In this study, we reconstructed 21 important samples by high-resolution micro-computed tomography to investigate coral growth pattern and parameter. Our skeleton and canal reconstructions revealed characteristics of different coral species and we further visualized the growth axes and growth rings to reveal coral growth directions. We drew a skeleton gray-scale map and calculated coral skeleton void ratios to reveal skeletal diversity, devising a method to quantify coral growth. On the bases of the 3D reconstructions and growth parameters, we investigated growth strategies of different coral species. This work extends the knowledge of how reef-building corals grow their colonies, giving a hint on reef forming regulation. The data of this paper contain large amount of coral growth information, and can be used in further research on reef forming patterns under different conditions. The method used in this study can also be applied in animals with porous skeletons.

Similar to most countries, the Brazilian water resources management considers topographically delineated catchment as a territorial unit for policy implementation. Yet, previous studies have shown that catchments are not hydrologically isolated, and topographic limits often neglect the groundwater boundaries. Thus, studies on effective catchment area are promising for shedding light on inter-catchment groundwater flow. Here, we investigated the deviation between the topographic and effective areas across Brazil. We applied the Effective Catchment Area index (ECI) to 733 Brazilian catchments and identified the most influencing attributes on the ECI by using Principal Component and Random Forest Analyses (PCA and RFA, respectively). Further analysis of consistency was carried out by contrasting the ECI values against the expected range of the Budyko curve considering both topographic and effective catchment areas (classic and adjusted framework). Considering the studied catchments, 15% and 16% of their effective areas were respectively smaller than half (strong losing water condition) and larger than double (strong gaining water condition) of their corresponding topographic areas. The aridity index was the main driving factor and negatively correlated with ECI followed by mean slope, precipitation seasonality, and mean elevation. In general, the more arid biomes in Brazil — the Cerrado and Caatinga — are prone to have smaller effective areas while larger effective areas were mostly found in the Atlantic Forest biome, a humid tropical region with a higher mean elevation. We highlight the potential of adopting a pooling of catchments based on their interconnectivity to minimize management costs while maximizing synergies and lessening trade-offs of water transfer processes. Our results contribute to a better country-scale understanding of hydrological connectivity among catchments and highlight the need to consider the effective catchment area to overcome water-food-energy security challenges on multiple scales.

A document by Ian Dickie. Click on the document to view its contents.

Introduction: Human atria comprise distinct epicardial layers, which can bypass endocardial layers and lead to downstream centrifugal propagation at the “epi-endo” connection. We sought to characterize anatomical substrates, electrophysiological properties, and ablation outcomes of “pseudo-focal” atrial tachycardias (ATs), defined as macroreentrant ATs mimicking focal ATs. Methods and Results: We retrospectively analyzed ATs showing centrifugal propagation with post-pacing intervals (PPIs) after entrainment pacing suggestive of a macroreentry. A total of 26 patients had pseudo-focal ATs consisting of 15 perimitral, 7 roof-dependent, and 5 cavotricuspid isthmus (CTI)-dependent flutters. A low-voltage area was consistently found at the collision site and co-localized with epicardial layers like the: (1) coronary sinus-great cardiac vein bundle (22%); (2) vein of Marshall bundle (15%); (3) Bachmann bundle (22%); (4) septopulmonary bundle (15%); (5) fossa ovalis (7%); and (6) low right atrium (19%). The mean missing tachycardia cycle length (TCL) was 67 ± 29 ms (22%) on the endocardial activation map. PPI was 9 [0-15] ms and 10 [0-20] ms longer than TCL at the breakthrough site and the opposite site, respectively. While feasible in 25 pseudo-focal ATs (93%), termination was better achieved by blocking the anatomical isthmus than ablating the breakthrough site [24/26 (92%) vs. 1/6 (17%); p < 0.001]. Conclusion: Perimitral, roof-dependent, and CTI-dependent flutters with centrifugal propagation are favored by a low-voltage area located at well-identified epicardial bundles. Comprehensive entrainment pacing maneuvers are crucial to distinguish pseudo-focal ATs from true focal ATs. Blocking the anatomical isthmus is a better therapeutic option than ablating the breakthrough site.

A 68-year-old female patient presented to the emergency department with left-sided weakness. Tissue plasminogen activator (tPA) was started for stroke, however, the patient was later found to have a type A intramural hematoma (IMH). TPA was subsequently discontinued. She was hemodynamically stable and was treated medically due to the risk of bleeding from tPA. Fortunately, the patient had a complete neurological recovery. She underwent an aortic repair 6 weeks after initial presentation and was discharged home without any complications. Aortic dissection and IMH should always be in the differential diagnosis when treating patients with signs of cerebral ischemia. This is the first documented case of accidental administration of tPA in a patient with intramural hematoma (IMH), and illustrates a successful case of delayed surgical repair for high risk IMH in patients recovering from cerebral ischemia.

This paper investigates the feedback stabilization of non-homogeneous delayed bilinear systems, evolving in Hilbert state space. More precisely, under observability like assumption, we prove the exponential and strong stability of the solution by using a bounded feedback control. The partial stabilization is discussed as well. The proof of the main results is based on the decomposition method. The decay estimates of the corresponding solution are obtained. Finally, some examples are presented.

Background/aim: The aim of this study was to evaluate the effects of general anesthesia and ultrasonography-guided interscalene block on pain and oxidative stress evaluated by thiol–disulphide balance and C-reactive protein levels in patients undergoing shoulder arthroscopy. Materials and methods: A total of 42 patients aged 18–75 years who were scheduled to undergo shoulder arthroscopy were randomized into interscalene block group (Group-IB, n = 20) and general anesthesia group (Group-GA, n = 22). All patients received patient-controlled analgesia during the postoperative period. Additional analgesics were administered to patients with a visual analog scale score of > 4. Native -thiol, total -thiol, disulphide and C-reactive protein levels were measured. Patients’ visual analog scale scores, morphine and additional analgesic consumption were recorded. A shift in thiol–disulphide balance toward decreased thiol and increased disulphide levels was regarded as an indicator of oxidative stress. Results: Pain level, morphine and additional analgesic consumption were higher in Group-GA. Native-thiol and total-thiol levels were higher in Group-IB postoperatively and also disulphide levels were lower at postoperative 18 hours. C-reactive protein levels were similar in both the groups. Conclusion: Interscalene block induced less oxidative stress during the postoperative period, as evaluated by thiol–disulphide balance.

Aims: It is evident that COVID-19 pandemic have affected the medical practice and training of residents. In this study, we evaluated the Physical Examination (PE) habits of residents working in a university hospital and how their PE practices did change during the pandemic. Methods: This single-center, non-interventional, cross-sectional descriptive study was conducted in a university hospital using an online survey questionnaire from 5 to 20 October 2020. Results: 308 residents participated in the study of whom 172 of them (55.8%) were female and the median age was 27 (IQR:3). Among all, 263 participants (85.4%) declared that they have worked in the areas where suspected/confirmed COVID-19 patients were being served. A total of 262 (85%) residents stated that PE habits have changed generally during the pandemic. There was a significant difference between those residents who have worked in the COVID-19 areas (n=230,87.5%) and those who have not (n=32, 71.1%) (p=0.004). PE habits of Internal Medicine Residents were more changed than others (p<0.001). The main reason for the change in PE habits in general (77.9%) and during the examination of suspected/confirmed COVID-19 patients (89.7%) were ‘’self-protection”. Reliance on laboratory and radiologic investigations during practice and not having a thought that less PE will disrupt the diagnosis and course of COVID-19 were also independent risk factors for performing less PE in suspected/confirmed COVID-19 patients. Discussion: This study clearly demonstrated that the COVID-19 pandemic has had a serious impact on the PE habits of the residents while examing patients in general and with COVID-19.

Steady increases in human population size and resource consumption levels are driving rampant agricultural expansion and intensification in some of the world's most pristine ecosystems. Habitat loss caused by agriculture puts the integrity of ecosystems at risk, and as a consequence, threatens the persistence of human societies that rely on ecosystem services to produce resources. Here we develop a spatially explicit model describing the coupled dynamics of an agricultural landscape and human population size to study the effect of different land-use management strategies, defined by the levels of agricultural clustering and intensification, on the sustainability of the social-ecological system. We show how gradual agricultural expansion can cause natural habitat to undergo a percolation transition leading to abrupt habitat fragmentation that feedbacks on human's decision making, causing faster agricultural expansion and aggravating habitat loss and fragmentation. We found that agricultural intensification to spare land from conversion is a successful strategy only in highly natural landscapes and that clustering agricultural land is the most effective measure to preserve landscape connectivity and avoid severe fragmentation. Our work highlights the importance of preserving large connected natural fragments in agricultural landscapes to enhance sustainability.

Background: Transcatheter closure of patent foramen ovale (PFO) is an effective therapy for preventing cryptogenic stroke (CS). The identification of high-risk PFO, which is more likely to be linked to CS, is essential. This study aimed to assess the accuracy of contrast transthoracic echocardiography (TTE) for evaluating large right-to-left (RL) shunt. Methods: We enrolled 119 patients with or without CS who were confirmed to have PFO. The severity of RL shunt evaluated by contrast TTE and transesophageal echocardiography (TEE) was classified as follows: small (<10 microbubbles), moderate (10–20 microbubbles), and large (>20 microbubbles). Results: With contrast TTE, large RL shunt was observed in 94 (79%) of 119 patients, including 66 of 74 with CS and 28 of 45 without CS. With contrast TEE, large RL shunt was observed in 33 (28%) patients, including 26 with CS and 7 without CS. Contrast TTE showed large RL shunt more frequently than contrast TEE (P < .01). Large RL shunt evaluated by contrast TTE had a sensitivity of 89% and an accuracy of 70% for the association with CS, whereas large RL shunt evaluated by contrast TEE had a sensitivity of 35% and an accuracy of 56%. Accuracy was significantly greater in contrast TTE than in contrast TEE (P = .02). Conclusion: Contrast TTE identified large RL shunt more frequently. Large RL shunt evaluated by contrast TTE provided greater accuracy for the association with CS. Our findings suggest that contrast TTE is valuable for evaluating large RL shunt as high-risk PFO.

Background: Complications using internal cardiac monitors are have been reported at a low rate. Targeted analyses of complications have not been well described. Objective: To investigate and describe complications associated with internal cardiac monitor (ICM) events reported to the FDA’s Manufacturer and User Facility Device Experience (MAUDE) database. Methods: Our team reviewed all reported events for the Reveal LINQ loop recorder submitted to the MAUDE database over seven years (1/1/2013-12/31/2019). A 5% random selection of reports was audited by two researchers to ensure report validity. Two cardiologists manually reviewed death and incongruent events for final interpretation. Results: 12,652 records were obtained during the observed time period. A total of 15,587 device complications were reported. Of this, under-sensing (n = 4509, 28.93%), premature discharge of battery (n = 3262, 20.93%), over-sensing (n = 2788, 17.89%), and other sensing issues (n = 1532, 9.83%) were most commonly reported. Patient adverse events were reported 1,030 times. Pain or discomfort (n = 275, 26.70%), site infection (n = 213, 20.68%), erosion (n = 138, 13.40%), and impaired healing (n = 49, 4.76%) were most commonly reported to affect patients. Death was reported four times; after expert review, no reports justified the device or procedure as a reasonable cause. Verification of events reported 99.53% accuracy of reporting. Conclusion: Several non-life-threatening ICM complications were commonly noted from the analysis. This study supports the safe use of ICMs. A better understanding of the complication profile will help providers select patients, provide informed consent, and expected management.

Emergence of Congenital Chagas Disease in Ireland and the UK. Stone RG1, Gavin P1, Nolder D2, McGettrick P3, Keogh A4, Mc Entagart N4, Drew R5, Lambert J3, Ferguson W11. Paediatric Infectious Diseases, Rotunda Hospital and Children’s Health Ireland at Temple Street, Dublin2. Diagnostic Parasitology Laboratory, The London School of Hygiene and Tropical Medicine, London, UK3. Infectious Diseases, The Mater Misericordiae University Hospital, Dublin4. Histopathology, Rotunda Hospital, Dublin5. Microbiology, The Rotunda Hospital, Dublin

The paper provides a study of the commutative algebras generated by iteration of the cross products in $\mathbb{C}^3$. Focusing on particular real forms we also consider the analytical properties of the corresponding rings of functions and relate them to different physical problems. Familiar results from the theory of holomorphic and bi-holomorphic functions appear naturally in this context, but new types of hypercomplex calculi emerge as well. The parallel transport along smooth curves in $\mathbb{E}^3$ and the associated Maurer-Cartan form are also studied with examples from kinematics and electrodynamics. Finally, the dual extension is discussed in the context of screw calculus and Galilean mechanics; a similar construction is studied also in the multi-dimensional real and complex cases.