Long-distance migration and venting of methane from the base of the hydrate stability zone

\ua9 2023, The Author(s).Marine methane hydrate is an ice-like substance that is stable in sediment around marine continental margins where water depths are greater than ~450–700 m. The release of methane due to melting of hydrates is considered to be a mechanism for past global carbon-cycle perturbations and could exacerbate ongoing anthropogenic climate change. Increases in bottom-water temperature at the landward limit of marine hydrate around continental margins, where vulnerable hydrate exists at or below the seabed, cause methane to vent into the ocean. However, this setting represents only ~3.5% of the global hydrate reservoir. The potential for methane from hydrate in deeper water to reach the atmosphere was considered negligible. Here we use three-dimensional (3D) seismic imagery to show that, on the Mauritanian margin, methane migrated at least 40 km below the base of the hydrate stability zone and vented through 23 pockmarks at the shelf break, probably during warmer Quaternary interglacials. We demonstrate that, under suitable circumstances, some of the 96.5% of methane bound in deeper water distal hydrates can reach the seafloor and vent into the ocean beyond the landward limit of marine hydrate. This reservoir should therefore be considered for estimating climate change-induced methane release during a warming world

The perceptions of undertaking a higher degree alongside orthodontic speciality training: a cross-sectional survey of British Orthodontic Society members

Introduction: In the UK, orthodontic speciality training takes place over three years full-time. In addition to the clinical training, there is an expectation that trainees undertake a higher degree. Currently, there is little evidence regarding the impact of undertaking a higher degree on specialist orthodontists. Aims: Investigate UK orthodontists' perceptions of undertaking a higher degree alongside speciality training. Materials and methods: A cross-sectional research study involving the distribution of an anonymous, descriptive, online, questionnaire-based survey between May and June 2021 via the British Orthodontic Society. Data were obtained in relation to the impact of undertaking a higher degree on the completion of speciality training, research skills, delivery of patient care and career opportunities. Results: In total, 166 questionnaires were completed (approximately 13.3% response rate). Most respondents 'agreed' or 'strongly agreed' that undertaking a higher degree had improved their scientific (77.1%) and critical appraisal skills (80.7%), job prospects (60.2%) and career opportunities (63.9%). Most respondents felt the benefits of the higher degree outweighed the associated costs (65.1%) and was a worthwhile component of training (69.3%). Conclusions: Specialist orthodontists place a high value on undertaking a higher degree. The results of this questionnaire should be of importance to stakeholders involved in the development of the orthodontic curriculum

Tiny grains shining bright in the gaps of Herbig Ae transitional discs

This is the final version. Available from the publisher via the DOI in this record.This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.This work presents a study of two Herbig Ae transitional discs, Oph IRS 48 and HD 169142; which both have reported rings in their dust density distributions. We use Keck-II/NIRC2 adaptive optics imaging observations in the L' filter (3.8 micron) to probe the regions of these discs inwards of ~20AU from the star. We introduce our method for investigating these transitional discs, which takes a forward modelling approach: making a model of the disc (using the Monte Carlo radiative transfer code RADMC), convolving it with point-spread functions of calibrator stars, and comparing the convolved models with the observational data. The disc surface density parameters are explored with a Monte Carlo Markov Chain technique. Our analysis recovers emission from both of the discs interior to the well known optically thick walls, modelled as a ring of emission at ~15AU in Oph IRS 48, and ~7AU for HD 169142, and identifies asymmetries in both discs. Given the brightness of the near-symmetric rings compared to the reported companion candidates, we suggest that the reported companion candidates can be interpreted as slightly asymmetric disc emission or illumination.European Research Council (ERC)Science and Technology Facilities Council Rutherford Fellowshi

Semi-Automated Design Space Exploration for Formal Modelling

Refinement based formal methods allow the modelling of systems through incremental steps via abstraction. Discovering the right levels of abstraction, formulating correct and meaningful invariants, and analysing faulty models are some of the challenges faced when using this technique. We propose Design Space Exploration that aims to assist a designer by automatically providing high-level modelling guidance

Hip and spine bone mineral density are greater in master sprinters, but not endurance runners compared with non-athletic controls

Summary: We examined bone density in older athletes and controls. Sprinters had greater hip and spine bone density than endurance athletes and controls, whereas values were similar in the latter two groups. These results could not be explained by differences in impact, muscle size or power between sprint and endurance athletes. Purpose: We examined the relationship between prolonged participation in regular sprint or endurance running and skeletal health at key clinical sites in older age, and the factors responsible for any associations which we observed. Methods: We recruited 38 master sprint runners (28 males, 10 females, mean age 71 ± 7 years), 149 master endurance runners (111 males, 38 females, mean age 70 ± 6 years) and 59 non-athletic controls (29 males, 30 females, mean age 74 ± 5 years). Dual X-ray absorptiometry was used to assess hip and spine bone mineral density (BMD), body composition (lean and fat mass), whilst jump power was assessed with jumping mechanography. In athletes, vertical impacts were recorded over 7 days from a waist-worn accelerometer, and details of starting age, age-graded performance and training hours were recorded. Results: In ANOVA models adjusted for sex, age, height, body composition, and jump power, sprinter hip BMD was 10 and 14% greater than that of endurance runners and controls respectively. Sprinter spine BMD was also greater than that of both endurance runners and controls. There were no differences in hip or spine BMD between endurance runners and controls. Stepwise regression showed only discipline (sprint/endurance), sex, and age as predictors of athlete spine BMD, whilst these variables and starting age were predictive of hip BMD. Conclusions: Regular running is associated with greater BMD at the fracture-prone hip and spine sites in master sprinters but not endurance runners. These benefits cannot be explained by indicators of mechanical loading measured in this study including vertical impacts, body composition or muscular output

Age-Related Declines in Lower Limb Muscle Function are Similar in Power and Endurance Athletes of Both Sexes: A Longitudinal Study of Master Athletes

The age-related decline in muscle function, particularly muscle power, is associated with increased risk of important clinical outcomes. Physical activity is an important determinant of muscle function, and different types of physical activity e.g. power-based versus endurance-based exercise appear to have differential effects on muscle power. Cross-sectional studies suggest that participation in power-based exercise is associated with greater muscle power across adulthood but this has not been investigated longitudinally. We recruited eighty-nine male and female power and endurance master athletes (sprint and distance runners respectively, baseline age 35–90y). Using jumping mechanography, we measured lower limb muscle function during a vertical jump including at least two testing sessions longitudinally over 4.5 ± 2.4y. We examined effects of time, discipline (power/endurance) and sex in addition to two- and three-way interactions using linear mixed-effects models. Peak relative power, relative force and jump height, but not Esslingen Fitness Index (indicating peak power relative to sex and age-matched reference data) declined with time. Peak power, force, height and EFI were greater in power than endurance athletes. There were no sex, discipline or sex*discipline interactions with time for any variable, suggesting that changes were similar over time for athletes of both sexes and disciplines. Advantages in lower limb muscle function in power athletes were maintained with time, in line with previous cross-sectional studies. These results suggest that improvements in lower limb function in less active older individuals following power-based training persist with continued adherence, although this requires further investigation in interventional studies

Greater maintenance of bone mineral content in male than female athletes, and in sprinting and jumping than endurance athletes: a longitudinal study of bone strength in elite masters athletes

Summary: We investigated longitudinal changes in tibia bone strength in master power (jumping and sprinting) and endurance (distance) athletes of both sexes. Bone mass but not cross‐sectional moment of inertia was better maintained in power than endurance athletes over time, particularly in men and independent of changes in performance. Objective: Assessment of effects of sex and athletic discipline (lower limb power events e.g. sprint running and jumping versus endurance running events) on longitudinal changes in bone strength in masters athletes. Methods: We examined tibia and fibula bone properties at distal (4% distal‐proximal tibia length) and proximal (66% length) sites using peripheral quantitative computed tomography (pQCT) in seventy‐one track and field masters athletes (30 male, 41 female, age at baseline 57.0±12.2y) in a longitudinal cohort study that included at least two testing sessions over a mean period of 4.2±3.1y. Effects of time, as well as time*sex and time*discipline interactions on bone parameters and calf muscle cross‐sectional area (CSA) were examined. Results: Effects of time were sex and discipline‐dependent, even following adjustment for enrolment age, sex, and changes in muscle CSA and athletic performance. Male sex and participation in power events was associated with better maintenance of tibia bone mineral content (BMC, an indicator of bone compressive strength) at 4% and 66% sites. In contrast, there was no strong evidence of sex or discipline effects on cross‐sectional moment of inertia (CSMI, an indicator of bone bending and torsional strength – P > 0.3 for interactions). Similar sex and discipline‐specific changes were also observed in the fibula. Conclusions: Results suggest that male athletes and those participating in lower limb power‐based rather than endurance‐based disciplines have better maintenance of bone compressive but not bending and torsional strength

How university’s activities support the development of students’ entrepreneurial abilities: case of Slovenia and Croatia

The paper reports how the offered university activities support the development of students’ entrepreneurship abilities. Data were collected from 306 students from Slovenian and 609 students from Croatian universities. The study reduces the gap between theoretical researches about the academic entrepreneurship education and individual empirical studies about the student’s estimation of the offered academic activities for development of their entrepreneurial abilities. The empirical research revealed differences in Slovenian and Croatian students’ perception about (a) needed academic activities and (b) significance of the offered university activities, for the development of their entrepreneurial abilities. Additionally, the results reveal that the impact of students’ gender and study level on their perception about the importance of the offered academic activities is not significant for most of the considered activities. The main practical implication is focused on further improvement of universities’ entrepreneurship education programs through selection and utilization of activities which can fill in the recognized gaps between the students’ needed and the offered academic activities for the development of students’ entrepreneurial abilities

Greater maintenance of bone mineral content in male than female athletes and in sprinting and jumping than endurance athletes: a longitudinal study of bone strength in elite masters athletes.

We investigated longitudinal changes in tibia bone strength in master power (jumping and sprinting) and endurance (distance) athletes of both sexes. Bone mass but not cross-sectional moment of inertia was better maintained in power than endurance athletes over time, particularly in men and independent of changes in performance. OBJECTIVE:Assessment of effects of sex and athletic discipline (lower limb power events, e.g. sprint running and jumping versus endurance running events) on longitudinal changes in bone strength in masters athletes. METHODS:We examined tibia and fibula bone properties at distal (4% distal-proximal tibia length) and proximal (66% length) sites using peripheral quantitative computed tomography (pQCT) in seventy-one track and field masters athletes (30 male, 41 female, age at baseline 57.0 ± 12.2 years) in a longitudinal cohort study that included at least two testing sessions over a mean period of 4.2 ± 3.1 years. Effects of time, as well as time × sex and time × discipline interactions on bone parameters and calf muscle cross-sectional area (CSA), were examined. RESULTS:Effects of time were sex and discipline-dependent, even following adjustment for enrolment age, sex and changes in muscle CSA and athletic performance. Male sex and participation in power events was associated with better maintenance of tibia bone mineral content (BMC, an indicator of bone compressive strength) at 4% and 66% sites. In contrast, there was no strong evidence of sex or discipline effects on cross-sectional moment of inertia (CSMI, an indicator of bone bending and torsional strength-P > 0.3 for interactions). Similar sex and discipline-specific changes were also observed in the fibula. CONCLUSIONS:Results suggest that male athletes and those participating in lower limb power-based rather than endurance-based disciplines have better maintenance of bone compressive but not bending and torsional strength