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Abstract At the edge of alpine and Arctic ecosystems all over the world, a transition zone exists beyond which it is either infeasible or unfavorable for trees to exist, colloquially identified as the treeline. We explore the possibility of a thermodynamic basis behind this demarcation in vegetation by considering ecosystems as open systems driven by thermodynamic advantage—defined by vegetation’s ability to dissipate heat from the earth’s surface to the air above the canopy. To deduce whether forests would be more thermodynamically advantageous than existing ecosystems beyond treelines, we construct and examine counterfactual scenarios in which trees exist beyond a treeline instead of the existing alpine meadow or Arctic tundra. Meteorological data from the Italian Alps, United States Rocky Mountains, and Western Canadian Taiga-Tundra are used as forcing for model computation of ecosystem work and temperature gradients at sites on both sides of each treeline with and without trees. Model results indicate that the alpine sites do not support trees beyond the treeline, as their presence would result in excessive CO $$_2$$ 2 loss and extended periods of snowpack due to temperature inversions (i.e., positive temperature gradient from the earth surface to the atmosphere). Further, both Arctic and alpine sites exhibit negative work resulting in positive feedback between vegetation heat dissipation and temperature gradient, thereby extending the duration of temperature inversions. These conditions demonstrate thermodynamic infeasibility associated with the counterfactual scenario of trees existing beyond a treeline. Thus, we conclude that, in addition to resource constraints, a treeline is an outcome of an ecosystem’s ability to self-organize towards the most advantageous vegetation structure facilitated by thermodynamic feasibility.

ABSTRACT. Objectives. To study the efficacy of otoacoustic emissions (OAEs) as a screening test for hearing impairment in children with acute bacterial meningitis. Hearing tests were performed before discharge from [...]

A new approach to making extremely large aspect ratio glass nano-fibers with diameters typically 20 – 40 nm is described. The fabrication process utilizes a novel phenomenon occurring with the interaction of focused high power femtosecond laser radiation with transparent media.

The influence of dopant concentration on the absorption of femtosecond mid-IR pulses is described. The measured results are compared to a theoretical absorption model.

High-repetition rate femtosecond laser radiation was utilized to improve surface quality of metal parts manufactured by laser additive techniques. This novel approach can be used to postprocess parts made of heat-sensitive materials, and to attain the designed net shape with micrometer precision.

The design of patient specific weight-bearing exercises after the surgical implementation of internal fixations is of critical importance for bone fracture healing. The purpose of this study is to theoretically investigate the effects of physiologically relevant dynamic loading on early stage of fracture healing under different locking compression plate (LCP) configurations. The finite element results show that dynamic loading enhanced transport of bone cells and growth factors in the fracture callus is much dependent on the flexibility of LCP. In comparison to free diffusion, a relatively flexible LCP together with dynamic loading could significantly enhance solute transport in callus. For example, a flexible LCP achieved by increasing WL (Working Length) and BPD (Bone Plate Distance) (e.g. WL=100 mm and BPD=2 mm) together with a 5-h 150 N@1 Hz dynamic loading could increase the uptake of chondrocytes by around 280% compared to free diffusion, osteoblasts by around 180%, osteogenic growth factors by around 120% and chondrogenic growth factors by around 220%. In addition, dynamic loading enhanced transport of cells and growth factors under LCP is spatially dependent with a relatively higher enhancement in far cortex zone than that in near cortex zone. The outcomes from present study could potentially assist orthopaedic surgeons to determine optimal loading regimes with consideration of patient specific LCP configurations. • Enhanced cell transport under dynamic loading depends on fixation flexibility. • Far cortical zone exhibit higher enhancement of cell uptake than near cortical zone. • Chondrocyte enhancement is higher in relatively smaller gap size of 1 mm. • Higher loading magnitude produce better mesenchymal stem cells enhancement. [ABSTRACT FROM AUTHOR]

Background Rotator cuff tears following anatomic total shoulder arthroplasty increase with duration of follow-up. This study aimed to evaluate contact pressure between the rotator cuff tendons and prosthesis after anatomic total shoulder arthroplasty and compare these with the tendon-contact pressures in the native shoulder. Methods Eight entire upper extremities were mounted onto a testing apparatus, and simulated muscle loading was applied to each rotator cuff tendon with the shoulder positioned in abduction, internal rotation, and external rotation. Pressure-sensitive film placed between each tendon and bone was used to measure the resultant tendon contact pressures. Experiments were repeated after anatomic total shoulder arthroplasty using standardized implant sizes, and pressure-sensitive film was used to evaluate tendon-prosthesis contact pressure. Results Both joint angle and shoulder joint replacement surgery had significant effects on the maximum contact pressure measured between the humeral head and all rotator cuff tendons (P <.05) except the teres minor. The supraspinatus demonstrated a significantly larger peak tendon contact pressure after surgery at 45° of abduction relative to that in the native shoulder (mean difference, 0.2 MPa; P =.031), while the subscapularis had a significantly larger maximum contact pressure at 10° of abduction (mean difference, 0.45 MPa; P =.032) and 90° of abduction (mean difference, 0.80 MPa; P =.008) postoperatively. Conclusion Anatomic total shoulder arthroplasty results in significantly larger tendon contact pressures relative to those in the native shoulder. High tendon contact pressures may ultimately predispose rotator cuff tendons to postoperative wear-induced damage and tearing. [ABSTRACT FROM AUTHOR]

Background: Laparoscopic anti-reflux surgery has become the standard treatment for symptomatic gastro-oesophageal reflux disease refractory to medical therapy. Successful anti-reflux surgery involves safe, minimally invasive surgery, resulting in symptom resolution with minimal side effects. This study aims to assess the feasibility and safety of day case anti-reflux surgery focussing on peri- and post-operative outcomes as a measure of success.Methods: Data was collected from the hospital database from 2003 to 2012. Data collection included demographics, surgeon, mode of admission, length of stay and complications. Electronic records were independently scrutinised for all patients with a length of stay of more than two nights.Results: 723 patients underwent laparoscopic fundoplication ± small hiatus hernia repair (<5 cm) with a day case rate of 67.1%. The 30 day readmission rate in these patients was 2.9% (21/723 patients). Nine patients had a failure of their initial laparoscopic fundoplication (defined as recurrence of symptoms). Three patients required a re-operation within 12 months of their initial procedure (re-operation rate = 0.41% (3/723 patients)).Conclusion: Laparoscopic hiatal surgery can be performed safely as a day case in high volume specialist centres with good outcomes. Raising the national standard for day case fundoplication promotes good practice and should be the model for future commissioning. [ABSTRACT FROM AUTHOR]

Designing weight-bearing exercises for patients with lower-limb bone fractures is challenging and requires a systematic approach that accounts for patient-specific loading conditions. However, 'trial-and-error' approaches are commonplace in clinical settings due to the lack of a fundamental understanding of the effect of weight-bearing exercises on the bone healing process. Whilst computational modelling has the potential to assist clinicians in designing effective patient-specific weight-bearing exercises, current models do not explicitly account for the effects of muscle loading, which could play an important role in mediating the mechanical microenvironment of a fracture site. We combined a fracture healing model involving a tibial fracture stabilised with a locking compression plate (LCP) with a detailed musculoskeletal model of the lower limb to determine interfragmentary strains in the vicinity of the fracture site during both full weight-bearing (100% body weight) and partial weight-bearing (50% body weight) standing. We found that muscle loading significantly altered model predictions of interfragmentary strains. For a fractured bone with a standard LCP configuration (bone-plate distance = 2 mm, working length = 30 mm) subject to full weight-bearing, the predicted strains at the near and far cortices were 23% and 11% higher when muscle loading was included compared to the case when muscle loading was omitted. The knee and ankle muscles accounted for 38% of the contact force exerted at the knee joint during quiet standing and contributed significantly to the strains calculated at the fracture site. Thus, models of bone fracture healing ought to account explicitly for the effects of muscle loading. Furthermore, the study indicated that LCP configuration parameters play a crucial role in influencing the fracture site microenvironment. The results highlighted the dominance of working length over bone-plate distance in controlling the flexibility of fracture sites stabilised with LCP devices. [Display omitted] • The importance of muscle loading on fracture healing analyses in highlighted. • Muscle loads could be up to 38% of the joint loads for quiet standing. • Omitting muscle loads may lead up to 25% error in interfragmentary strain predictions. [ABSTRACT FROM AUTHOR]

Obesity has been identified as an independent risk factor for a wide range of health conditions. Therefore, there is a clear need for high quality Bariatric research in order to improve patient selection, outcomes and safety for patients with obesity. We sought to identify and compare the quantitative and qualitative publication output from Bariatric centres in England. We identified 42 National Health Service (NHS) Trusts and 162 surgeons providing Bariatric services in England. A median of 4 (range 1–7) Bariatric surgeons were identified per centre. Eight NHS Trusts (19%) and 75 surgeons (46.3%) had no Bariatric publications during the study period, while 87 surgeons published a total of 432 Bariatric papers. Only 15 surgeons (9%) had ≥10 publications within the study period. However, these surgeons produced >50% of all Bariatric publications. Departments with more than 4 surgeons produced a significantly higher number of Bariatric publications (median 8.5 vs 2, p = 0.01). There is significant variation in research contribution amongst Bariatric centres in England. Academia should be encouraged and promoted across all bariatric services in order to broaden our understanding on Bariatric outcomes by expanding the service and proportional increase in funding. Given that a number of health conditions can afflict individuals living with obesity, bariatric surgery research becomes all the more important. [ABSTRACT FROM AUTHOR]