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Background: Oesophageal perforation is an uncommon surgical emergency associated with high morbidity and mortality. The timing and type of intervention is crucial and there has been a major paradigm shift towards minimal invasive management over the last 15 years. Herein, we review our management of spontaneous and iatrogenic oesophageal perforations and assess the short- and long-term outcomes. Methods: We performed a retrospective review of consecutive patients presenting with intra-thoracic oesophageal perforation between January 2004 and Dec 2020 in a single tertiary hospital. Results: Seventy-four patients were identified with oesophageal perforations: 58.1% were male; mean age of 68.28 ± 13.67 years. Aetiology was spontaneous in 42 (56.76%), iatrogenic in 29 (39.2%) and foreign body ingestion/related to trauma in 3 (4.1%). The diagnosis was delayed in 29 (39.2%) cases for longer than 24 h. There was change in the primary diagnostic modality over the period of this study with CT being used for diagnosis for 19 of 20 patients (95%). Initial management of the oesophageal perforation included a surgical intervention in 34 [45.9%; primary closure in 28 (37.8%), resection in 6 (8.1%)], endoscopic stenting in 18 (24.3%) and conservative management in 22 (29.7%) patients. On multivariate analysis, there was an effect of pathology (malignant vs. benign; p = 0.003) and surgical treatment as first line (p = 0.048) on 90-day mortality. However, at 1-year and overall follow-up, time to presentation (≤ 24 h vs. > 24 h) remained the only significant variable (p = 0.017 & p = 0.02, respectively). Conclusion: Oesophageal perforation remains a condition with high mortality. The paradigm shift in our tertiary unit suggests the more liberal use of CT to establish an earlier diagnosis and a higher rate of oesophageal stenting as a primary management option for iatrogenic perforations. Time to diagnosis and management continues to be the most critical variable in the overall outcome. [ABSTRACT FROM AUTHOR]

Filamentation is favorable for many long-range outdoor laser applications, some of which require propagation to or at high altitudes. Understanding how the filamentation process and filament properties are impacted by the low pressure conditions present at high altitudes is essential in designing effective applications. The scaling of filament preconditions with pressure is considered. An increase in critical power and decrease in transition numerical aperture (NA) is predicted to occur with a drop in pressure, indicating that nonlinear pulse propagation and filamentation at high altitudes requires higher energy and a longer assisted focal length than sea level filamentation. A summary of pressure-scaled filament properties is also presented. New simulations demonstrate filamentation at pressures as low as 0.0035 atm (38.5 km altitude) is possible. [ABSTRACT FROM AUTHOR]

Medical educators recognize the value of reflection for medical students and the role creative writing can play in fostering this. However, direct creative writing tasks can be challenging for many students, particularly those with limited experience in the arts and humanities. An alternative strategy is to utilize an indirect approach, engaging students with structured tasks that obliquely encourage reflection. This paper reports one such approach. We refer to this approach as in-verse reflection, playing on both the structure of the writing and its novel approach to reflection. Students were invited to write, in verse-like structures, about their personal and clinical experiences as medical students. Thematic analysis of their creative outputs and reactions identified four principal themes: the challenges of life as a medical student, the emotional demands of the medical course, a sense of connectedness and solidarity with fellow students, and a sense of marginality within the hospital system. Students generally found the tasks highly engaging and conducive to reflection, producing texts representing significant insights into their experiences as medical students. The reported method offers a relatively simple, structured, and guided approach to reflective writing, adding to the repertoire of methods available to educators in the medical humanities. [ABSTRACT FROM AUTHOR]

Spatially resolved wavefront measurements are presented during nonlinear self-collapse and provide the first detailed characterization of wavefront evolution during filament formation. The wavefront dynamics of key nonlinear processes including Kerr self-focusing, ionization and plasma defocusing, and dynamic spatial replenishment are identified and resolved in both the filament core and reservoir regions. These results are analyzed and interpreted with respect to numerical simulations and provide insight into fundamental aspects of filamentation. They also inform applications based on phase manipulation, such as external beam guiding, and present a new method for measuring the nonlinear index of refraction, n2. [ABSTRACT FROM AUTHOR]

Purpose: We aimed to apply bibliometric tools to Australian and New Zealand orthopaedic publications produced between 2008 and 2018 to identify the most highly cited publications, author and institution collaboration networks and topic trends. Analysis of the literature can highlight areas of emerging interest and knowledge gaps, and direct future research.Methods: A systematic search was conducted using Clarivate Analytics Web of Science. Citation analysis was carried out using Web of Science. Collaboration networks were constructed using chord diagrams. Trends in publication topics were analysed using simple linear regression to find the rate of change of publication volume on each topic.Results: A total of 3097 publications contributed to by 8855 individual authors met inclusion criteria. Across the study period, there was a large increase in the annual volume of publications on the topic of ACL (Anterior Cruciate Ligament) surgery. We also found that collaboration between Australian and New Zealand authors was very low with only 1% (n = 31) of publications including authors from both countries and 0.4% (n = 12) including orthopaedic surgeons or trainees from both.Conclusions: Publications on ACL surgery have increased over the past decade, likely due to the presence of competing surgical approaches and the recently recognized risk of osteoarthritis following ACL reconstruction. The overall collaboration between Australian and New Zealand authors was very low which lends itself to opportunities for future research. [ABSTRACT FROM AUTHOR]

After fracture, mesenchymal stem cells (MSCs) and growth factors migrate into the fracture callus to exert their biological actions. Previous studies have indicated that dynamic loading induced tissue deformation and interstitial fluid flow could produce a biomechanical environment which significantly affects the healing outcomes. However, the fundamental relationship between the various loading regimes and different healing outcomes has not still been fully understood. In this study, we present an integrated computational model to investigate the effect of dynamic loading on early stage of bone fracture healing. The model takes into account cell and growth factor transport under dynamic loading, and mechanical stimuli mediated MSC differentiation and tissue production. The developed model was firstly validated by the available experimental data, and then implemented to identify the loading regimes that produce the optimal healing outcomes. Our results demonstrated that dynamic loading enhances MSC and growth factor transport in a spatially dependent manner. For example, compared to free diffusion, dynamic loading could significantly increase MSCs concentration in endosteal zone; and chondrogenic growth factors in both cortical and periosteal zones in callus. Furthermore, there could be an optimal dynamic loading regime (e.g. 10% strain at 1 Hz) which could potentially significant enhance endochondral ossification. [ABSTRACT FROM AUTHOR]

Purpose: Mechanical gastro-intestinal anastomosis using stapler is a critical step in laparoscopic Roux-en-Y gastric bypass (RYGB). To date the effect of the direction of staples on anastomotic leak has not been investigated. The study aim was to investigate the impact of the direction of staples on the integrity of the gastro-jejunal anastomosis.Materials and Methods: Eight gastro-jejunostomy (GJ) models were performed using porcine stomach and small intestine. Specimens were divided into group A where the cartridge was in the gastric lumen with the anvil in the jejunal lumen and vice versa in group B. Enterotomy was closed and gastric and jejunal ends were stapled off. Burst pressure (BP) was measured by infusion of methylene blue saline into the GJ model until leak occurred. Site of leak, BP, and total volume (TV) infused were recorded. Compliance (C) was calculated from the equation ΔTV/ΔBP.Results: The BP was greater in group A compared to group B (18 mmHg (range 15-25) versus 11 mmHg (range 8-15); p = 0.045) despite similar TV between the groups 60.00 mL (range 55.00-65.00) versus 51.25 mL (range 40.00-60.00); p = 0.11). The compliance did not significantly differ between groups A and B (6.38 mL/mmHg (range 4.34-8.59) versus 5.61 mL/mmHg (range 3.93-7.21); p = 0.48).Conclusion: BP recorded when the stapler cartridge was introduced in the gastric lumen was higher than when it was introduced from the jejunal lumen. The lack of difference in compliance between groups suggests that the difference in BP was due to the difference in the direction of staples. [ABSTRACT FROM AUTHOR]

With demographic change and increasing life expectancy, osteoporotic fractures have become one of the most prevalent trauma conditions seen in daily clinical practice. A variety of factors are known to affect the rate of healing in osteoporotic conditions (e.g. both biochemical and biomechanical environment of callus cells). However, the influence of impairment of mesenchymal stem cell function in the osteoporotic condition on bone fracture healing has not been fully understood. In the present study, we develop a mathematical model that quantifies the change in biological processes within the fracture callus as a result of osteoporosis. The model includes special features of osteoporosis such as reduction in mesenchymal stem cell (MSC) number in osteoporotic bone, impaired response of osteoporotic MSCs to their biomechanical microenvironment and the effects of configuration of locking compression plate (LCP) system on healing in this context. The results presented here suggest that mechanically-mediated MSCs differentiation at early stages of healing are significantly affected under osteoporotic conditions, while it is predicted that the flexible fixation achieved by increasing bone-plate distance of LCP could alleviate the negative effects of osteoporosis on healing. The outcomes of this study could potentially lead to patient specific surgical solutions, and thus achieve optimal healing outcomes in osteoporotic conditions. [ABSTRACT FROM AUTHOR]

A self-developed nanosecond-pulsed thulium fiber laser operating at the wavelength λ = 2 μm was used to selectively modify the front and the back surfaces of various uncoated and metal-coated silicon and gallium arsenide wafers utilizing transparency of semiconductors at this wavelength. This novel processing regime was studied in terms of the process parameter variations, i.e., pulse energy and pulse duration, and the corresponding modification fluence thresholds were determined. The results revealed nearly debris-free back surface processing of wafers, in which modifications could be induced without affecting the front surfaces. The back surface modification threshold of Si was significantly higher than at the front surface due to non-linear absorption and aberration effects observed in experiments. A qualitative study of the underlying physical mechanisms responsible for material modification was performed, including basic analytical modeling and z-scan measurements. Multi-photon absorption, surface-enhanced absorption at nano- and microscopic defect sites, and damage accumulation effects are considered the main physical mechanisms accountable for consistent surface modifications. Applications of trans-wafer processing in removal of thin single- and multi-material layers from the back surface of Si wafers, both in single tracks and large areas, are presented. [ABSTRACT FROM AUTHOR]

Interfragmentary movement (IFM) at the fracture site plays an important role in fracture healing, particularly during its early stage, via influencing the mechanical microenvironment of mesenchymal stem cells within the fracture callus. However, the effect of changes in IFM resulting from the changes in the configuration of locking plate fixation on cell differentiation has not yet been fully understood. In this study, mechanical experiments on surrogate tibia specimens, manufactured from specially formulated polyurethane, were conducted to investigate changes in IFM of fractures under various locking plate fixation configurations and loading magnitudes. The effect of the observed IFM on callus cell differentiation was then further studied using computational simulation. We found that during the early stage, cell differentiation in the fracture callus is highly influenced by fracture gap size and IFM, which in turn, is highly sensitive to locking plate fixation configuration. The computational model predicted that a small gap size (e.g. 1 mm) under a relatively flexible configuration of locking plate fixation (larger bone-plate distances and working lengths) could experience excessive strain and fluid flow within the fracture site, resulting in excessive fibrous tissue differentiation and delayed healing. By contrast, a relatively flexible configuration of locking plate fixation was predicted to improve cartilaginous callus formation and bone healing for a relatively larger gap size (e.g. 3 mm). If further confirmed by animal and human studies, the research outcome of this paper may have implications for orthopaedic surgeons in optimising the application of locking plate fixations for fractures in clinical practice. [ABSTRACT FROM AUTHOR]

Purpose: Re-establishment of the native footprint during rotator cuff repair is important for maximizing healing potential and fixation strength. The purpose of this study was to evaluate the contact area, contact pressure, stiffness and tensile strength of a new single-row cruciate suture repair and to compare these results to those of the Mason-Allen, double-row and transosseous repairs. Methods: Infraspinatus tendons from fifty-six lamb shoulders were harvested and randomly assigned to cruciate suture, Mason-Allen, double-row and transosseous repair groups. Repairs were performed over pressure-sensitive film and footprint contact area and pressure measured. Repaired tendon specimens were also loaded in uniaxial tension, and ultimate tensile strength and stiffness measured. Results: The cruciate suture repair established significantly greater footprint contact area compared to the Mason-Allen repair (mean difference = 101 mm, p = 0.003). The ultimate tensile strength and stiffness of the double-row repair was significantly higher than that of all other repair groups ( p < 0.05). The average footprint contact pressure of the cruciate suture repair (0.78 MPa) was similar to that of the Mason-Allen (0.74 MPa) and double-row repairs (0.79 MPa). The ultimate tensile strength of the cruciate suture repair was significantly greater than that of the transosseous repair (mean difference 62.4 N, p = 0.002). Conclusion: The cruciate suture repair may improve strength and healing at the repaired tendon rotator cuff insertion relative to other single-row repair techniques. It may represent a faster, easier and more cost-effective alternative to double-row repairs. [ABSTRACT FROM AUTHOR]

Laser filamentation in gases is often carried out in the laboratory with focusing optics to better stabilize the filament, whereas real-world applications of filaments frequently involve collimated or near-collimated beams. It is well documented that geometrical focusing can alter the properties of laser filaments and, consequently, a transition between a collimated and a strongly focused filament is expected. Nevertheless, this transition point has not been identified. Here, we propose an analytical method to determine the transition, and show that it corresponds to an actual shift in the balance of physical mechanisms governing filamentation. In high-NA conditions, filamentation is primarily governed by geometrical focusing and plasma effects, while the Kerr nonlinearity plays a more significant role as NA decreases. We find the transition between the two regimes to be relatively insensitive to the intrinsic laser parameters, and our analysis agrees well with a wide range of parameters found in published literature. [ABSTRACT FROM AUTHOR]

Kerr self-focusing of high-power ultrashort laser pulses in atmosphere may result in a structure or structures of high intensity that can propagate over long distances with little divergence. Filamentation has garnered significant interest in the nonlinear optics community due to its unique properties. Salient features of filaments include a central region of intense laser power (greater than the ionization threshold of the propagation medium) and a low temperature plasma column that lasts up to nanoseconds in duration after the passage of the laser pulse. Steel and titanium samples are ablated by filaments and by sharply focused sub-picosecond laser pulses. We then performed metrology on the samples to compare the ablation features in addition to modeling of the plasma ablation process. Ablation with filaments leads to a wider range of material responses as compared to ablation with sharply focused pulse. This results in potential complications for applications of filament ablation that depends on the rate of material removal and spectroscopic analysis. [ABSTRACT FROM AUTHOR]

We report femtosecond pulse generation and chirped pulse amplification in Tm:fiber. A mode-locked oscillator operating in the soliton regime produced 800 fs pulses with 5 nm spectral bandwidth, at 40 pJ pulse energy. This oscillator seeded a pre-amplifier that utilizes a Raman soliton self-frequency shift to produce wavelength tunable pulses with 3 nJ energy, reduced pulse duration of 150 fs, and increased bandwidth of 30 nm. For further amplification, the pulses were stretched up to 160 ps using a chirped Bragg grating (CBG). Stretched pulses were amplified to 85 nJ after compression in single-mode Tm:fiber and recompressed with the CBG as short as 400 fs. Compressed pulses were coupled into a highly nonlinear tellurite fiber to investigate the potential of this ultrashort pulse 2-μm fiber source as a pump for mid-IR supercontinuum generation. [ABSTRACT FROM AUTHOR]

There is an increasing trend towards operative treatment for displaced midshaft clavicle fractures. This retrospective study was performed to assess the outcome of delayed fixation of displaced midshaft clavicle fractures and test the null hypothesis that there is no difference in results between early and delayed surgical treatment for displaced midshaft clavicle fractures. Using the hospital database, two groups of patients who were surgically treated using Herbert cannulated screw for displaced midshaft clavicle fractures were identified. There were 114 cases in acute (median time to operation of 5 days) and 21 cases in delayed groups (median time to operation 10.5 weeks). Thirty-five cases were available for follow-up in the acute and 16 cases in the delayed series. The primary outcome was assessed by the Disabilities of the Arm, Shoulder and Hand (DASH) score, American Shoulder and Elbow Surgeons score (ASES) and Constant-Murley score. Union occurred in 14 cases in the delayed group. The median DASH, mean ASES and Constant-Murley scores were 4.1, 97 and 88.7, respectively. Compared with the delayed group, the early group had a higher union rate ( P = 0.033), trend towards lower DASH score ( P = 0.051), and higher ASES score ( P = 0.047). The delayed group had significantly more problems with prominent, symptomatic screws that required removal ( P = 0.002). There were no significant differences in union time and complication rate. Delayed fixation of displaced midshaft fractures using the Herbert cannulated bone screw and bone graft is effective and provides a good functional outcome that only slightly reduced from that recorded for early fixation. [ABSTRACT FROM AUTHOR]

Nondestructive three-dimensional imaging of femtosecond laser-written buried structures is demonstrated using optical coherence microscopy providing lateral and depth resolution on a micron scale. This high speed technique, which requires no sample preparation, enables the visualization of volumetric structural modification created deep in transparent dielectric medium with high signal/noise contrast. Images of buried void structures with dimensions as large as 190 μm in length were obtained without shadowing effects impugning the image fidelity. [ABSTRACT FROM AUTHOR]

Hemorrhage-related mortality (HRM) associated with pelvic fractures continues to challenge trauma care. This study describes the management and outcome of hemodynamically unstable patients with a pelvic fracture, with emphasis on primary intervention for hemorrhage control and HRM. Blunt trauma patients [Injury Severity Score (ISS) ≥16] with a major pelvic fracture (Abbreviated Injury Score, pelvis ≥3) and hemodynamic instability [admission systolic blood pressure (SBP) ≤90 mmHg or receiving ≥6 units of packed red blood cells (PRBCs)/24 hours) were included into a 48-month (ending in December 2003) multicenter retrospective study of 11 major trauma centers. Data are presented as the mean ± SD. A total of 217 patients (mean age 41 ± 19 years, 71% male, ISS 42 ± 16) were studied. The admission SBP was 96 ± 37 mmHg and the Glascow Coma Scale (GCS) 11 ± 5. Patients received 4 ± 2 liters of fluids including 4 ± 4 units of PRBCs in the emergency room (ER). In total, 69 (32%) patients died, among whom the HRM was 19%; 29% of the deaths were due to pelvic bleeding. Altogether, 120 of the 217 (55%) patients underwent focused abdominal sonography for trauma (FAST) or diagnostic peritoneal aspiration (DPA) and diagnostic peritoneal lavage (DPL); 60 of the 217 (28%) patients were found to have pelvic binding in the ER. In all, 53 of 109 (49%) patients had no bleeding noted at laparotomy, 26 of 106 (25%) had no abdominal findings, and 15 of 53 (28%) had had no prior abdominal investigation (FAST/DPL/computed tomography). Angiography was positive in 48 of 58 (83%) patients. The HRM was highest in patients with laparotomy as the primary intervention (29%) followed by the angiography group (18%), the combined laparotomy/pelvic fixation group (16%), and the pelvic fixation-only group (10%). HRM associated with major pelvic trauma is unacceptably high especially in the laparotomy group. Hence, nontherapeutic laparotomy must be avoided, concentrating instead on arresting pelvic hemorrhage. Standards of care must be implemented and abided by. [ABSTRACT FROM AUTHOR]

Alcohol absorption and/or metabolism along with sensitivity to alcohol is altered in most patients following gastric bypass surgery [[1]-[3]]. ASMBS (American Society for Metabolic & Bariatric Surgery) guidelines suggest that the patients undergoing bariatric surgery should be screened and educated regarding alcohol intake both prior and following bariatric surgery [[4]]. Statement of Informed Consent An informed consent was taken from the patient and documented in patient's medical records. [Extracted from the article]

Veress was a Hungarian physician who designed this needle to prevent damage to the lungs or abdominal organs, either during drainage from the thoracic or peritoneal cavity or decompression of pneumothorax [[2]]. The commonly stated reason behind shunning the Veress needle is safety, with many citing the risk of visceral injury, vascular injury, and air embolism. This review found a 0.2% risk of vascular injury, a 0.4% risk of visceral injury, and a 1.7% risk of failed entry with a Veress needle. [Extracted from the article]

Extra-long PCR (XL-PCR) was used to assess the relative concentration of functional full-length mitochondrial DNA (mtDNA) in single type I human vastus lateralis muscle fibres of defined cytochrome c oxidase (COX) activity. Type I muscle fibres rely more on mitochondrial oxidative phosphorylation for their energy demands, compared to the other common fibre types (IIa, IIab and IIb) that principally depend on glycolysis for their energy requirements. A total of 60 single type I fibres were analyzed from 15 individuals (8 males and 7 females) of various ages. COX positive muscle fibres were shown to contain amplifiable full-length mtDNA together with a small number of mtDNA rearrangements. By contrast, COX negative fibres did not contain detectable full-length mtDNA, but did contain a heterogeneous mixture of rearranged mtDNA species with the frequency and occurrence of each deletion varying considerably from fibre to fibre. These data lead us to the conclusion that the level of COX activity in type I muscle fibres is reflected by the amount of amplifiable full-length mtDNA. It is proposed that the amount of amplifiable full-length mtDNA constitutes the functional fraction of the total mtDNA. A comprehensive hypothesis that relates the dynamics of mtDNA turnover, mtDNA mutations, mtDNA damage and repair to the ageing process is discussed. [ABSTRACT FROM AUTHOR]

Focuses on how increasing the presence of foreign firms in a country will affect domestic welfare. Illustration of the relationship between domestic welfare and foreign firms; View that major entry into a foreign market may be harmful; Concerns from exporters about improving their access to foreign markets.

An Incremental Incentive Scheme (IIS) encourages some activity by rewarding an agent for overachieving a base level determined by past performance but not penalizing underachievement. We examine an IIS R&D subsidy in a dynamic model due to Grossman and Shapiro (1986). We show that the firm's optimal R&D path either cycles around the no-subsidy path or follows a ‘ratchet’ pattern of small increases in R&D relative to the no-subsidy path. A simple condition determines which type of behavior occurs. Furthermore, we show that an IIS may be an inefficient method of encouraging R&D compared to a flat-rate subsidy. [ABSTRACT FROM AUTHOR]

This paper considers the enforcement of intellectual property rights in an international setting. 1 consider some of the traditional problems associated with protection of such rights in a closed economy and discuss complication, added by an international dimension. Globally-optimal and nationally-optimal policies are compared. A simple model of policy choices is derived and optimal tax/subsidy and rights enforcement policies demonstrated. The paper concludes with a brief discussion of the current U.S. approach of discriminatory treatment on the basis of the national origin of an infringing product and argues that it is inferior to subsidies for providing incentives for R&D and to tariffs for shifting profits to U.S. firms. [ABSTRACT FROM AUTHOR]

A correction to the article "Acute Management of Hemodynamically Unstable Pelvic Trauma Patients: Time for a Change? Multicenter Review of Recent Practice," published in previous issue, is presented.