Incidence of occult appendiceal neoplasm in patients over 40 years with acute appendicitis: A single-institution review.

OBJECTIVE: To investigate the incidence of occult appendiceal neoplasm in patients aged 40 years and over who underwent appendicectomy for appendicitis. METHODS: The clinical coding electronic database was used to identify patients aged 40 years and over who were diagnosed with appendicitis from September 2010 to September 2022. Patients were included if they were managed operatively. DESIGN: Retrospective cohort study. SETTING: Modified Monash category 3 (large rural town). PARTICIPANTS: Patients aged 40 years and over undergoing appendicectomy for appendicitis. MAIN OUTCOME MEASURES: Incidence of appendiceal neoplasm within appendicectomy specimen. RESULTS: A total of 279 patients aged 40 years and over underwent appendicectomy, with a median age of 53 years (range 40-95). Nineteen patients (7%) were found to have a primary neoplastic lesion within the appendix: seven neuroendocrine neoplasms (37%), six sessile serrated lesions (32%), two colonic-type adenocarcinoma (11%), two goblet cell adenocarcinoma (11%) and two appendiceal mucinous neoplasms (11%). Additionally, one patient had a metastatic adenocarcinoma of pancreaticobiliary aetiology. CONCLUSIONS: Occult appendiceal neoplasm was higher than reported in the literature in our cohort. This would support appendicectomy as the treatment of choice for patients aged 40 years and over with acute appendicitis and caution against nonoperative management in this demographic.

Two-chip power-scalable THz-generating semiconductor disk laser.

We demonstrate a compact two-chip terahertz-emitting vertical-external-cavity surface-emitting laser source, which provides 1 THz output based on intracavity frequency conversion of dual-wavelength emission in a periodically poled lithium niobate crystal. The type-I frequency conversion scheme at room temperature highly benefits from the power-scaling possibilities in a multi-chip cavity with intracavity powers in excess of 500 W.

Mortality after emergency abdominal surgery in a non-metropolitan Australian centre.

OBJECTIVE: Emergency abdominal surgery has poorer outcomes and higher mortality rates, compared with elective surgery. Serious morbidity or mortality occurs in up to 40% of patients. No information is available with regard to the outcome of patients undergoing emergency abdominal surgery in rural Australia. METHODS: Patients undergoing emergency abdominal surgery in a 110-bed rural surgical centre in South Australia over a 5 year period (January 2010-December 2014) were included in the study. Patient data were retrieved using the hospital database and review of patient records. RESULTS: A total of 4396 general surgical emergency admissions was recorded. Emergency admissions without intervention, endoscopic intervention only, appendectomy, cholecystectomy or urological or gynaecological diagnoses were excluded from mortality analysis. The remaining 237 patients underwent major abdominal emergency surgery for bowel obstruction (benign and malignant: n = 143, 60%), injury/inflammation/perforation/peritonitis (n = 85, 36%) or haemorrhage/ischaemia (n = 9, 3.8%). Thirty- (n = 9) and 90- (n = 12) day mortality rates were 3.8% and 5.1%, respectively. CONCLUSION: Emergency abdominal surgery can be safely provided in non-metropolitan Australian centres, with a low 30-day mortality rate of 3.8% and a 90-day mortality rate of 5.1%. This compares well with results published by other national and international investigators.

Intraoperative cholangiogram during laparoscopic cholecystectomy: A clinical trial in rural setting.

OBJECTIVE: The routine use of intraoperative cholangiogram (IOC) in laparoscopic cholecystectomy (LC) remains a contentious issue. IOC helps to delineate biliary tree anatomy, prevent bile duct injury and image stones in the common bile duct (CBD). It may prove to be a valuable alternative to ERCP or MRCP, especially in the rural setting with limited resources. DESIGN/SETTING/PARTICIPANTS/INTERVENTIONS/MAIN OUTCOME MEASURES: All patients undergoing laparoscopic cholecystectomy during a 12-month period were audited. For the first 6 months, patients were recruited for routine IOC and for the second 6 months, routine IOC was not performed. Cases were analysed with regard to patient demographics, operative details and clinical outcomes. RESULTS: A total of 75 patients were analysed within the 12-month period. The majority were women aged 41-50. Ultrasound suggested common bile duct stones in 6.7% of cases. IOC was attempted in 50.7% of cases. Of these, 29 (76.3%) were successful. IOC added an average of 28 min to total theatre time. A total of 75% (n = 22) of IOCs showed normal flow of contrast into the intra- and extra-hepatic biliary systems. In 17% (n = 5) of patients, stones within the CBD were suspected, and these were referred for further management. ERCP/MRCP confirmed CBD stones in 60% (n = 3) of these patients. There was poor correlation between pre-operative suspicion and confirmed CBD stones (two patients only with pre-operative suspected CBD stone confirmed on IOC and ERCP). There were no operative complications related to IOC. There were no post-operative complications in cases where no IOC was done. CONCLUSION: The majority of patients treated in our centre were women, middle-aged patients booked for elective laparoscopic cholecystectomy. Although only 6.7% cases were suspicious for CBD stones pre-operatively, a total of 17% of patients with routine IOC suggested CBD stones. IOC was found to be safe, taking only an additional 28 min of total theatre time. Routine rather than selective use of IOC could be considered to improve patient safety and long-term results.

Self-mode-locking semiconductor disk laser.

The development of mode-locked semiconductor disk lasers received striking attention in the last 14 years and there is still a vast potential of such pulsed lasers to be explored and exploited. While for more than one decade pulsed operation was strongly linked to the employment of a saturable absorber, self-mode-locking emerged recently as an effective and novel technique in this field - giving prospect to a reduced complexity and improved cost-efficiency of such lasers. In this work, we highlight recent achievements regarding self-mode-locked semiconductor devices. It is worth to note, that although nonlinear effects in the active medium are expected to give rise to self-mode-locking, this has to be investigated with care in future experiments. However, there is a controversy whether results presented with respect to self-mode-locking truly show mode-locking. Such concerns are addressed in this work and we provide a clear evidence of mode-locking in a saturable-absorber-free device. By using a BBO crystal outside the cavity, green light originating from second-harmonic generation using the out-coupled laser beam is demonstrated. In addition, long-time-span pulse trains as well as radiofrequency-spectra measurements are presented for our sub-ps pulses at 500 MHz repetition rate which indicate the stable pulse operation of our device. Furthermore, a long-time-span autocorrelation trace is introduced which clearly shows absence of a pedestal or double pulses. Eventually, a beam-profile measurement reveals the excellent beam quality of our device with an M-square factor of less than 1.1 for both axes, showing that self-mode-locking can be achieved for the fundamental transverse mode.

A 23-watt single-frequency vertical-external-cavity surface-emitting laser.

We report on a single-frequency semiconductor disk laser which generates 23.6 W output power in continuous wave operation, at a wavelength of 1013 nm. The high output power is a result of optimizing the chip design, thermal management and the cavity configuration. By applying passive stabilization techniques, the free-running linewidth is measured to be 407 kHz for a sampling time of 1 ms, while undercutting 100 kHz in the microsecond domain.

Self-mode-locked quantum-dot vertical-external-cavity surface-emitting laser.

We present the first self-mode-locked optically pumped quantum-dot semiconductor disk laser. Our mode-locked device emits sub-picosecond pulses at a wavelength of 1040 nm and features a record peak power of 460 W at a repetition rate of 1.5 GHz. In this work, we also investigate the temperature dependence of the pulse duration as well as the time-bandwidth product for stable mode locking.

Evolution of multi-mode operation in vertical-external-cavity surface-emitting lasers.

The longitudinal multi-mode emission in a vertical-external-cavity surface-emitting laser is investigated using both single shot streak camera measurements and interferometric measurement techniques. For this, the laser is operated in the single- and two-color emission regime using both an etalon and a free-running configuration without etalon, respectively. The laser emission is analyzed with respect to pump power and output coupling losses for a long and for a short resonator. We observe a steep increase of emission bandwidth close to the laser threshold and monitor the transition between longitudinal single- and multi-mode operation. Additionally, the results indicate that a stable two-color operation is related to a sufficiently high number of oscillating longitudinal modes within each color.

Colorectal adenomatous and serrated polyps in rural South Australia: who, why, what and where?

BACKGROUNDS: The adenoma-carcinoma and serrated pathways offer a window of opportunity for the removal of pre-malignant polyps and prevention of colorectal cancer (CRC) through the use of colonoscopy. The aim of this study was to investigate variation in polyp incidence in different age groups, gender and indications for undertaking colonoscopy. We also address histological types of polyps found and where in the bowel they are located. METHODS: This study is based on the colonoscopy data collected prospectively over a one-year period in multiple South Australian rural centres, 24 general surgeons contributed to this study. All histopathology results were subsequently entered into the dataset. RESULTS: A total of 3497 colonoscopies were performed, with a total of 2221 adenomatous and serrated polyps removed. Both serrated and adenomatous polyps were more common in the distal colon. Patients of male gender, aged 70 years and over and with an indication of polyp surveillance had higher adenoma and serrated polyp detection rates (ADR and SPDR). Patients aged 40-49 years old who underwent colonoscopy for positive faecal occult blood had an ADR and SPDR of 25.0% and 6.3%, respectively. CONCLUSIONS: This study has shown variation in ADR and SPDR depending on age, gender and indication for colonoscopy. This variation will help further develop key performance indicators in colonoscopy. The high ADR and SPDR in patients aged 40-49 years old whom underwent colonoscopy for positive faecal occult blood may support lowering the age of commencement of CRC screening in Australia.

The role of screening colonoscopy after appendicitis in patients over 40 years of age.

BACKGROUND: There is some evidence of the association between acute appendicitis and colorectal neoplasm in patients over the age of 40 years. Despite this, few centres routinely evaluate the colon endoscopically following an episode of appendicitis in these patients. Our aim was to investigate the incidence of colorectal neoplasm in patients aged 40 years and over who underwent screening colonoscopy following acute appendicitis. METHODS: Retrospective cohort study of patients aged 40 years and over who were diagnosed with acute appendicitis via imaging or histology between January 2015 and May 2022. Findings on subsequent screening colonoscopy were evaluated and classified according to adenomatous and non-adenomatous lesions. RESULTS: A total of 176 patients met inclusion criteria, with a median age of 54 years (range 40-92) and female to male ratio of 1:1.3. One hundred patients (56%) had a colonoscopy following their admission, at a mean duration of 3.5 months post discharge. 15% of patients had an adenomatous polyp detected (10 adenomas, 4 advanced adenomas, and 1 sessile serrated adenoma), and 9% had a non-adenomatous lesion detected (8 hyperplastic polyps and 1 lipoma). CONCLUSION: Adenoma detection rate in patients aged 40 years and over undergoing colonoscopy after acute appendicitis was 15% in our cohort. This high adenoma detection rate supports the view of appendicitis as an indication for screening faecal immunochemical testing or colonoscopy in patients above 40 years.

Quality of rural colonoscopy outperforms key performance indicators in a multi-centre prospective clinical study.

BACKGROUND: High-quality colonoscopy is vital for the detection and removal of adenomatous polyps and early diagnosis of colorectal cancer. The aim of this study was to prospectively assess the quality and safety of colonoscopies performed in the non-metropolitan setting. Key performance indicators measured include completion, polypectomy and adenoma/serrated polyp detection rates, rate of adequate bowel preparation, withdrawal time and complications. METHODS: Prospective data collection for all colonoscopies performed over a one-year period in seven non-metropolitan South Australian hospitals. Two general surgeons and twelve registrars working in rural South Australian hospitals (Mount Gambier, Millicent, Naracoorte, Port Lincoln, Port Augusta, Whyalla and Berri) contributed to this study. RESULTS: In total 3497 colonoscopies were analysed. Complete colonoscopy was achieved in 96.1%. The adenoma detection and serrated polyp detection rates were 25.6% and 5.4% respectively. Cancer was detected in 71 patients (2%). Colonic perforation occurred in five patients (0.1%). There was no procedure-related mortality. CONCLUSIONS: Colonoscopy performed in the non-metropolitan Australian setting outperforms key performance indicators set by national institutions. This is the first Australian prospective multi-centre study investigating the quality and safety of endoscopic procedures.

Outcomes of laparoscopic colorectal cancer surgery in a non-metropolitan Australian hospital: audit of 120 patients with long-term follow-up results.

BACKGROUND: Laparoscopic colorectal cancer surgery has been shown to produce comparable oncological long-term results as well as improved short-term outcomes compared to open surgery in multicentre trials. Limited information is available whether these results are reproduced in non-metropolitan surgery. METHODS: Audit of prospectively collected follow-up data in a rural surgical centre in South Australia. Short- and long-term results of colorectal cancer patients undergoing elective laparoscopic surgery for cure. Outcomes are compared with results of open surgery. RESULTS: Survival and clinical data of 120 patients after laparoscopic resection were analysed and then benchmarked against results of 157 open resections. Conversion rate was 10.8% (N = 13). Mean patient age was 69.9 years. Mean number of lymph nodes analysed was 15.5. Mean follow-up is 53.0 months. Thirty-day mortality was 0.36% (n = 1) and 90-day mortality was 0.72% (n = 2). No differences in complications rates, long term survival or procedures performed were observed. This is a single centre audit of clinical and oncological outcomes and a number of exclusion criteria were applied. Patient gender, cancer stages as well as number of patients undergoing neoadjuvant radio-chemotherapy differ significantly between the study and the benchmarking group. Patients were not randomized and the benchmarking group is in part a historical control. CONCLUSIONS: This audit of clinical outcomes and survival after laparoscopic CRC resection for cure indicates that minimal invasive surgery may be suitable for adequately staffed and equipped rural centres.

Terahertz Brewster lenses.

Typical lenses suffer from Fresnel reflections at their surfaces, reducing the transmitted power and leading to interference phenomena. While antireflection coatings can efficiently suppress these reflections for a small frequency window, broadband antireflection coatings remain challenging. In this paper, we report on the simulation and experimental investigation of Brewster lenses in the THz-range. These lenses can be operated under the Brewster angle, ensuring reflection-free transmission of p-polarized light in an extremely broad spectral range. Experimental proof of the excellent focusing capabilities of the Brewster lenses is given by frequency and spatially resolved focus plane measurements using a fiber-coupled THz-TDS system.

Laparoscopic cholecystectomy--comparison of early postoperative results in an Australian rural centre and a German university hospital.

BACKGROUND: Laparoscopic cholecystectomy is the treatment of choice for symptomatic gallstone disease. Cultural as well as organisational differences can result in significant variations of postoperative length of stay. AIM OF THE PRESENT STUDY: The aim of this study is to evaluate whether differences in postoperative length of stay and early postoperative outcome can be observed by comparison of an Australian rural centre and a German university hospital. RESULTS: Between February 2006 and August 2007 (18 months), 359 patients (140 Australia, 219 Germany) underwent laparoscopic cholecystectomy. Mean patient age was 50.4 +/- 1.5 and 53.5 +/- 1.0 years, respectively. Seventy-seven percent of the Australian and 62% of the German patients were female. Twenty-one percent and 20% of the procedures were emergencies, respectively. Median American Society of Anaesthesiologists score of all patients was two. The conversion rate was 8% in both centres. A 4% complication rate was observed in Australia (N = 5, 3x bile leak, 1x postoperative bleeding and 1x wound infection) as opposed to 3% in Germany (N = 7, 2x bile leak, 2x postoperative bleeding and 3x wound infection). Postoperative length of stay in Australia was 1.8 +/- 0.1 days (median 1 day) and was significantly longer in patients after emergency surgery (1.6 +/- 0.1 versus 2.6 +/- 0.3 days, p < 0.018). Postoperative length of stay in Germany was 3.7 +/- 0.2 days (median 3 days), and no significant differences were observed when elective and emergency procedures were compared (3.5 +/- 0.2 versus 3.9 +/- 0.5 days, p > 0.05). Comparison of treatment results indicates a significantly shorter postoperative stay in Australia (3 days versus 1 day, p < 0.001). DISCUSSION/CONCLUSION: In rural Australia, a median postoperative stay of 1 day after laparoscopic cholecystectomy can be safely achieved. Postoperative length of stay is significantly longer in the German setting with otherwise comparable patients and surgical techniques. Simple changes of pre- and postoperative management of elective as well as emergency laparoscopic cholecystectomy will allow, for substantial cost savings, for the German health system.

A systematic scoping review of determinants of multidisciplinary cancer team access and decision-making in the management of older patients diagnosed with colorectal cancer.

Early diagnosis of colorectal cancer (CRC) and access to optimal treatment achieves optimal cancer outcomes. However, CRC survival inequalities persist with a lower survival rate for older patients (≥65 years). Although the reasons for poorer cancer survival in older people are complex, evidence suggests that these patients are less likely to receive best practice care as indicated by access to multidisciplinary team (MDT) care. Three electronic databases were systematically searched to examine factors that affect access to, and clinical decision-making, in the context of MDT care of older people with CRC. We included studies reporting empirical data relating to predictors for a patient's case being discussed at a MDT meeting and/or factors that impact treatment decision-making during the meeting. From 303 returned titles and abstracts, eighteen articles were reviewed. Eight studies specifically selected older patients, with eligibility criteria varying from ≥65 to ≥80 years. Five articles explored predictors of MDT access, with all articles identifying age as a negative, and advanced stage as a positive predictor of MDT discussion. Fourteen studies explored factors that influenced the MDT decision-making process, with older age and presence of comorbid disease negatively influencing treatment decisions (cases less often discussed and/or treatment not recommended). A few studies identified access to a MDT discussion as an independent predictor for CRC treatment. Access to the MDT process for older patients with a CRC diagnosis should be based on relevant geriatric domains rather than on chronological age alone, which is expected to allow more appropriate clinical decision-making and reduce treatment inequities for older patients with cancer.

Human-mediated dispersal and disturbance shape the metapopulation dynamics of a long-lived herb.

As anthropogenic impacts on the natural world escalate, there is increasing interest in the role of humans in dispersing seeds. But the consequences of this Human-Mediated Dispersal (HMD) on plant spatial dynamics are little studied. In this paper, we ask how secondary dispersal by HMD affects the dynamics of a natural plant metapopulation. In addition to dispersal between patches, we suggest within-patch processes can be critical. To address this, we assess how variation in local population dynamics, caused by small-scale disturbances, affects metapopulation size. We created an empirically based model with stochastic population dynamics and dispersal among patches, which represented a real-world, cliff-top metapopulation of wild cabbage Brassica oleracea. We collected demographic data from multiple populations by tagging plants over eight years. We assessed seed survival, and establishment and survival of seedlings in intact vegetation vs. small disturbances. We modeled primary dispersal by wind using field data and used experimental data on secondary HMD by hikers. We monitored occupancy patterns over a 14-yr period in the real metapopulation. Disturbance had large effects on local population growth rates, by increasing seedling establishment and survival. This meant that the modeled metapopulation grew in size only when the area disturbed in each patch was above 35%. In these growing metapopulations, although only 0.2% of seeds underwent HMD, this greatly enhanced metapopulation growth rates. Similarly, HMD allowed more colonizations in declining metapopulations under low disturbance, and this slowed the rate of decline. The real metapopulation showed patterns of varying patch occupancy over the survey years, which were related to habitat quality, but also positively to human activity along the cliffs, hinting at beneficial effects of humans. These findings illustrate that realistic changes to dispersal or demography, specifically by humans, can have fundamental effects on the viability of a species at the landscape scale.

Human-mediated dispersal of seeds over long distances.

Human activities have fundamental impacts on the distribution of species through altered land use, but also directly by dispersal of propagules. Rare long-distance dispersal events have a disproportionate importance for the spread of species including invasions. While it is widely accepted that humans may act as vectors of long-distance dispersal, there are few studies that quantify this process. We studied in detail a mechanism of human-mediated dispersal (HMD). For two plant species we measured, over a wide range of distances, how many seeds are carried by humans on shoes. While over half of the seeds fell off within 5m, seeds were regularly still attached to shoes after 5 km. Semi-mechanistic models were fitted, and these suggested that long-distance dispersal on shoes is facilitated by decreasing seed detachment probability with distance. Mechanistic modelling showed that the primary vector, wind, was less important as an agent of long-distance dispersal, dispersing seeds less than 250 m. Full dispersal kernels were derived by combining the models for primary dispersal by wind and secondary dispersal by humans. These suggest that walking humans can disperse seeds to very long distances, up to at least 10 km, and provide some of the first quantified dispersal kernels for HMD.

Terahertz birefringence for orientation analysis.

A terahertz time-domain spectrometer is employed to study different birefringent samples. We develop a method based on the temporal waveform and the impulse response of a sample to map the anisotropy of their inner structure. To validate our algorithm, we study the polarization-affecting structure of various classes of materials such as crystals, plastics, and natural products. Among all samples we observe the largest birefringence for a rutile crystal with Deltan=3.3 at 1 THz.