bluuebunny/crossref_metadata_2025 huggingface dataset:
Προβλήματα σχεδιασμού ανάδρασης συστημάτων ελέγχου
Authors: Χρυσάφη Αικατερίνη
Published: May 2023

Η παρούσα διατριβή κλιμακώνεται σε δύο αυτόνομα και ανεξάρτητα μέρη, σε καθένα από τα οποία μελετάται και ένα διαφορετικό πρόβλημα ελέγχου και παρουσιάζονται διαφορετικές μεθοδολογίες σχεδιασμού ανάδρασης για το εκάστοτε σύστημα. Κατά το πρώτο μέρος, παρουσιάζουμε ένα νέο σχήμα προσαρμοστικού συνοριακού ελέγχου για παραβολικές Μερικές Διαφορικές Εξισώσεις (ΜΔΕ) στις οποίες εμφανίζονται άγνωστες παράμετροι. Το εν λόγω σχήμα, είναι βασισμένο στην αρχή της certainty equivalence και συνοδεύεται από έναν εκτιμητή ελαχίστων τετραγώνων ο οποίος λειτουργεί με event-triggering βασισμένο στο μέγεθος του regulation error. Επιπλέον, το νέο σχήμα εγγυάται εκθετική σύγκλιση της κατάστασης στο μηδέν ως προς την L^{2} νόρμα, καθώς και σύγκλιση των εκτιμήσεων των άγνωστων παραμέτρων στις πραγματικές τους τιμές εντός πεπερασμένου χρόνου. Η αντίστοιχη ανάλυση πραγματοποιείται με σημείο αναφοράς ένα συγκεκριμένο πρόβλημα αρχικών-συνοριακών τιμών με συνοριακές συνθήκες τύπου Dirichlet, όπου οι μοναδικές άγνωστες παράμετροι είναι ο reaction coefficient και το high frequency gain. Αξίζει να σημειωθεί ότι για το συγκεκριμένο πρόβλημα, δεν είχε αναπτυχθεί πρότινος κάποιο προσαρμοστικό σχήμα ελέγχου το οποίο μπορεί να χειριστεί την άγνωστη παράμετρο του high frequency gain. Επιπλέον, παρατίθεται ένα αντιπροσωπευτικό παράδειγμα όπου επιτρέπεται η σύγκριση του σχήματος που περιγράφεται, με άλλα προσαρμοστικά σχήματα ελέγχου που έχουν προταθεί στη βιβλιογραφία.Το δεύτερο μέρος εστιάζει στην επέκταση πρόσφατων αποτελεσμάτων από τη βιβλιογραφία σχετικά με τη σταθεροποίηση γραμμικών ως προς τον έλεγχο μη γραμμικών συστημάτων, μέσω δειγματοληπτικής ανάδρασης. Συγκεκριμένα, εξάγονται ικανές συνθήκες οι οποίες εξασφαλίζουν σταθεροποίηση με χρήση δειγματοληπτικής και χρονικά μεταβαλλόμενης ανάδρασης σε μια μεγάλη κατηγορία μη γραμμικών συστημάτων ελέγχου των οποίων τα δυναμικά είναι γραμμικά στην είσοδο. Οι προτεινόμενες συνθήκες εκφράζονται μέσω της Lie άλγεβρας των δυναμικών του συστήματος, καθώς και μιας γενικευμένης συνάρτησης ελέγχου Lyapunov. Τα κεντρικά αποτελέσματα αποτελούν γενικεύσεις του γνωστού Θεωρήματος “Artstein-Sontag” πάνω στην ασυμπτωτική σταθεροποίηση μέσω μιας σχεδόν λείας ανάδρασης. Η ανάλυση που πραγματοποιείται, περιορίζεται στην περίπτωση μιας εισόδου σε γραμμικά ως προς τον έλεγχο μη γραμμικά συστήματα με μη μηδενικό drift term, ωστόσο, τα εξαγόμενα συμπεράσματα μπορούν εύκολα να επεκταθούν και για την περίπτωση πολλαπλών εισόδων.
IMPACT OF THE COMPANY’S DEGREE OF ENVIRONMENTAL, SOCIAL AND CORPORATE GOVERNANCE (ESG) ON THE COST OF ITS SOURCES OF FINANCING
Authors: Izmailova Dilyara K. , Mamoudou Hamidou Ben , Pirozhkov Maxim A.
Published: May 2023

This article is devoted to the impact of ESG on the cost of sources of corporate finance. The topic of the article is relevant, as the world is moving to ESG investing, reflecting a growing sentiment about how ESG considerations can affect portfolios and individual securities. ESG investing is a form of socially responsible investing that prioritizes financial returns as well as a company’s impact on the environment, its stakeholders and the planet. The authors have highlighted in detail the criteria used to assess companies for ESG investing and the various issues covered by these. The article gives a brief history of ESG and how it has evolved over time. It also notes different tools used to help with sustainable investing. And at the end, the authors present an ESG rating and how scores can vary between companies, which may use different measures and weighting systems.
FORECASTING SALES OF AN INNOVATIVE PRODUCT BASED ON SIMULATION MODELING
Authors: Gajkova Luybov V.
Published: May 2023

The use of simulation modeling for forecasting sales of an innovative product is considered as one of the methods of regulating sales in the conditions of digitalization of the economy.

Purpose: construction of a simulation model for forecasting the sale of an innovative product in order to maintain an appropriate level of life activity of the able-bodied population in the conditions of digitalization of the economy.

Methodology: the dialectical method is used as a general scientific method of cognition; techniques and tools of system, comparative analysis and generalization; methods and tools of simulation modeling.

Results: an approach to the study of sales forecasts of an innovative product based on discrete-event simulation modeling as the basis of analytical processing of the obtained data is described.

Scope of results: the heads of companies in solving the issues of determining the optimal volume of sales of an innovative product as one of the components of the element of market infrastructure in the conditions of digitalization of the economy.
DEVELOPMENT OF A RESOURCE MANAGEMENT METHODOLOGY FOR A SERVICE COMPANY
Authors: Avetisyan Tatiana V. , Lvovich Yakov E. , Preobrazhenskiy Andrey P. , Preobrazhensky Yuri P.
Published: May 2023

This article discusses the specifics of managing a service-related company. It shows how the preparation of input data and their transformation takes place. Peculiarities of model preparation for training and testing are demonstrated. The general scheme of interaction between customer end-users and project and third-party technical support taking into account the conditions of service maintenance is given. The scheme of logic of processing incoming incidents between support lines is shown. The logic diagram of the prediction module for determining the support team is given. After the work has received the trained model that allows to carry out prediction of a support team on the basis of methods of logistic regression, by means of language Python it can be saved as a special file, it can then be connected as an independent module.

Purpose. Determination of methods and techniques of analysis used in the analysis of export operations.

Methodology the article used systems analysis and enterprise management methods.

Results: an example of resolved incident data for a specific support team with engineers is considered, as well as an example of numerical feature calculations to adjust the support team engineer’s baseline prediction. A logic diagram of the improved software solution model is shown.

Practical implications can be used with the improvement of IT service management in terms of incident coordinator activities.
ASSESSING THE COINTEGRATION OF INFLATION AND PRODUCTIVITY: THE EXAMPLE OF RUSSIA AND THE COUNTRIES OF THE WEST AFRICAN ECONOMIC AND MONETARY UNION (UEMOA)
Authors: Portnov Aleksandr V. , Viku Kojovi Nelson Krepin V.
Published: May 2023

The article presents an assessment of the cointegration of inflation and productivity indicators on the example of: Russia and UEMOA countries. As part of the study, an attempt was made to assess the presence of a long-term balance between the studied indicators for a more detailed understanding of the economic nature of two categories: “productivity” and “inflation”. The spatial aspect was chosen by the authors not by chance, since it allowed the analysis to be carried out, considering the peculiarities of different countries in presenting data with different frequencies: if monthly data are available, this provides long time series, cointegration, which can be estimated by the classical method. In the case of annual data, the time series are short, and the authors propose to evaluate the cointegration of such series using a nonparametric method. The article presents a comparative analysis of the results obtained for the countries under study based on the use of parametric and non-parametric estimation methods. The non-parametric method for assessing the probability of cointegration was used for the first time in the context of inflation and productivity indicators.

Purpose. Determine the cointegration of inflation and labor productivity as an assessment of economic development.

Methodology: parametric and non-parametric methods for assessing cointegration were used in the article.

Results: data were obtained comparing the probabilities of cointegration of inflation and labor productivity, considering the territorial aspect and the level of economic development.

Practical implications: application of a non-parametric method for assessing cointegration in the framework of economic analysis.
ОЦЕНКА ЭКОНОМИЧЕСКОЙ ЭФФЕКТИВНОСТИ МЕРОПРИЯТИЙ ПО ЭНЕРГОСБЕРЕЖЕНИЮ В СФЕРЕ ЖИЛИЩНО-КОММУНАЛЬНОГО ХОЗЯЙСТВА
Authors: Surovtsov Maksim M. , Moreva Yuliya A. , Novoselova Yuliya N.
Published: May 2023

Энергосбережение является стратегическим направлением развития экономики Российской Федерации. Львиная доля потребления энергоресурсов приходится на жилищно-коммунальное хозяйство. Важную роль в экономии тепловой энергии, затрачиваемой на отопление жилищного фонда, играет качество их теплозащиты. В настоящее время в эксплуатации находится огромное количество зданий, построенных до ввода в действие современных норм по требованиям теплозащиты. Показатели удельных расходов тепловой энергии на отопление в таких зданиях значительно превышают значения для современных зданий, построенных с учетом актуальных требований и норм. В связи с этим представляет интерес поиск правильного технико-экономического решения – согласиться с увеличенными расходами тепловой энергии или проводить утепление наружных ограждающих конструкций. В статье приведена оценка результатов определения приведенного сопротивления теплопередаче наружных стен жилого здания, эксплуатируемого с 1970 г. Для рассматриваемого здания предложен вариант утепления наружных ограждений в соответствии с действующими нормами, определена сметная стоимость строительно-монтажных работ. Определена экономическая целесообразность выполнения мероприятий по повышению теплозащиты наружных ограждающих конструкций обследуемого здания.

Цель – определение эффективного способа управления объектами жилищного фонда с учетом политики энергосбережения.

Метод или методология проведения работы: в статье использовались результаты натурного эксперимента, а также технико-экономические методы анализа.

Результаты: определены показатели, определяющие технико-экономическую целесообразность проведения энергосберегающих мероприятий для эксплуатирующихся объектов жилой застройки.

Область применения результатов: полученные результаты целесообразно применять на уровне управляющих компаний или муниципалитетов.
DIAGNOSIS OF SKIN MELANOMA: CURRENT STATUS AND PROSPECTS (literature review)
Authors: Guseynov Arif , Guseynov T. , Sedov S.
Published: May 2023

The work is devoted to the diagnosis of skin melanoma. The article reflects the main factors affecting the survival of patients. The basic principles of melanoma diagnostics are presented. Methods for diagnosing skin melanoma, including invasive and non-invasive methods, are described in detail and with justification. Of the non-invasive methods for diagnosing skin melanoma, the role of physical examination and dermatoscopy in case of suspected melanoma is emphasized. Of the instrumental methods of examination, the use of such research methods as ultrasound, computed tomography, magnetic resonance imaging, positron emission tomography is con sidered. From laboratory methods, methods of molecular genetic research and determination of skin melanoma biomark ers are presented. Of the invasive methods, the use of biopsy methods such as excisional and incisional biopsy is considered, with specification of indications and contraindications for their use. At the end of the work, the main requirements for the early diagnosis of skin melanoma are listed. In conclusion, the latest trends in the diagnosis of skin melanoma, new non-invasive methods and an algorithm for diagnosing skin melanoma are identified.
CLINICAL CASE SYSTEMIC SCLERODERMA A MIDDLE-AGED WOMAN
Authors: Demin M. , Avdeeva Ol'ga
Published: May 2023

Systemic scleroderma is a rare chronic disease characterized by the development of diffuse fibrosis, pathological changes in the skin, blood vessels, joints and internal organs.

The article presents a clinical case of a patient with systemic scleroderma with such obvious manifestations of skin and vascular lesions as sclerodactyly, masking of the face, "purse-string mouth", Raynaud's syndrome, as well as lesions of the joints, muscles, immunological disorders, the development of steroid osteoporosis with multiple fractures
The debut of systemic lupus erythematosus during pregnancy
Authors: Dvornikova O. , Belyaeva Elena
Published: May 2023

For a long time, systemic lupus erythematosus remains an insufficiently studied problem of rheumatology, the factors influencing the development and progression of the disease are not clear. The hormonal factor remains one of the possible triggers in the development of the disease in predisposed individuals. The course of pregnancy in patients with systemic lupus erythematosus is always associated with multiple risks. The onset of the disease during pregnancy often leads to the death of the fetus and the threat to the life of the mother. At the present stage, thanks to the possibilities of modern diagnostics and treatment, the prognosis for the life and health of both mother and fetus has improved. A case of the development of systemic lupus erythematosus during pregnancy and successful therapy with corticosteroids and belimumab is presented.
Technical Note—Characterizing and Computing the Set of Nash Equilibria via Vector Optimization
Authors: Feinstein Zachary , Rudloff Birgit
Published: May 2023

What is the relation between the notion of Nash equilibria and Pareto-optimal points? It is well known that Nash equilibria do not need to be Pareto optimal, and Pareto points do not need to be Nash equilibria. However, the paper “Characterizing and Computing the Set of Nash Equilibria via Vector Optimization” by Feinstein and Rudloff takes a deeper look at the relation. It is shown that it is possible to characterize the set of all Nash equilibria as the set of all Pareto-optimal solutions of a certain vector optimization problem. This is accomplished by carefully designing the objective function and the ordering cone of the vector optimization problem such that both notions coincide. This characterization holds for all noncooperative games (nonconvex, convex, linear). It opens up a new way of computing Nash equilibria, as one can now use techniques and algorithms from vector optimization to compute the set of all Nash equilibria, which is in contrast to the classical fixed-point iterations that find just a single Nash equilibrium.
Laparoscopic colorectal resections during the COVID-19 pandemic – business as usual?
Authors: Kalaiselvan R , Scott M , Rajasundaram R , Samad A
Published: May 2023

Introduction

To analyse the outcomes of major colorectal resections performed during the COVID-19 pandemic, to assess safety and explore all precautionary measures.

Method

All patients who underwent major elective colorectal resections at St Helens and Knowsley Teaching Hospital NHS Trust between 24th March 2020 (the date that the Royal Colleges of Surgery produced their guidelines re operating during the pandemic) and 17th April 2020 were analysed from a prospectively maintained database. The primary outcome was 7-day mortality and secondary outcomes were the development of a positive COVID-19 test consequent to hospital stay and the overall complication rate.

Results

In this 24 day time frame 27 patients (17 males) underwent elective colorectal resections at St Helens and Knowsley NHS Trust. The median age was 69 (41–84) years and median ASA was 2 (1–3). The median Body Mass Index was 30 (21–40.7). Twenty-five patients underwent surgery for cancer and two patients had urgent resections for low-grade sepsis secondary to diverticular colovesical fistulae. 24 patients underwent laparoscopic colorectal resections and 3 patients underwent planned open surgery. 7-day mortality was 0%, and no patients/staff contracted COVID-19 during the post-operative period. The overall complication rate was 14.8%. At a median follow-up of 29 (17–44) days via telephone, there have been no reported COVID-19 related symptoms in any of these patients.

Conclusion

Our experience demonstrated that it was possible to undertake laparoscopic colorectal resections despite the COVID-19 pandemic posing a major threat to humanity, providing that adequate and stringent precautions are undertaken.
Evaluating the potential utility of three-dimensional printed models in preoperative planning and patient consent in gastrointestinal cancer surgery
Authors: Povey M , Powell S , Howes N , Vimalachandran D , Sutton P
Published: May 2023

Introduction

The Future of Surgery report from the Royal College of Surgeons of England acknowledges the important role that three-dimensional imaging will play in support of personalised surgical interventions. One component of this is preoperative planning. We investigated surgeons’ and patients’ perceptions of this evolving technology.

Materials and methods

Ethical approval was obtained. From a normal computed tomography scan, three-dimensional models of the stomach, pancreas and rectum were rendered and printed on an Ultimaker™ three-dimensional printer. Semi-structured interviews were performed with surgeons and patients to explore perceived model effectiveness and utility. Likert scales were used to grade responses (1 = strongly disagree; 10 = strongly agree) and qualitative responses recorded.

Results

A total of 26 surgeons (9 rectal, 9 oesophagogastric, 8 pancreatic) and 30 patients (median age 62 years, interquartile range, IQR, 68–72 years; 57% male) were recruited. Median surgeon scores were effectiveness for preoperative planning, 6 (IQR 3–7), authenticity, 5 (IQR 3–6), likability, 6 (IQR 4–7), promoting learning, 7 (IQR 5–8), utility, 6 (IQR 5–7) and helping patients, 7 (IQR 5–8). Median patient scores were usefulness to the surgeon, 8 (IQR 7–9), authenticity, 8 (IQR 6–8), likability, 8 (IQR 7–8), helping understanding of condition, 8 (IQR 8–9), helping understanding of surgery, 8 (IQR 7–9) and feeling uncomfortable, 1 (IQR 1–4). Median overall decisional conflict score (0 = no; 100 = high) was 22 (IQR 19–28) and decision effectiveness was 25 (IQR 19–30).

Discussion

Overall, patients and surgeons considered that three-dimensional printed models were effective and had potential utility in education and, to a lesser extent, preoperative planning. Patient decisional conflict and effectiveness scores were weighted towards certainty in decision making but had room for improvement, which three-dimensional models may help to facilitate.
The impact of a fellow on a regional robotic-assisted partial nephrectomy service
Authors: Crockett MG , Malki M , Hussain M , Mueller G , Segaran S , Tadtayev S , Barber NJ
Published: May 2023

Introduction

Training a fellow has a cost in time and effort for the surgeon and their team. Their relative inexperience may also negatively affect the patient. The aim of this study was to determine and quantify the impact of a fellow on a regional robotic-assisted partial nephrectomy service and on perioperative outcomes.

Materials and methods

We reviewed the prospectively collected data for 522 patients who had undergone robotic-assisted partial nephrectomy since 2015 during the tenure of six fellows. Perioperative outcomes for three groups were compared: group A (no fellow participation), group B (some participation) and group C (fellow completed entire operation). We also reviewed progression over 12 months.

Results

Demographics were similar in all groups apart from the percentage of men, which was lower in group C (p < 0.05). Operative time was 27 minutes longer for group B (p < 0.001). Warm ischaemia time was significantly shorter for group A but the difference was only four minutes (p < 0.001). Length of stay was slightly shorter for group C compared with the other groups (p < 0.01). Trifecta achievement was greatest for group A (p < 0.001). There were no perioperative deaths in any group and positive margins, complications and readmissions were low and similar in all groups. Towards the end of their fellowship, fellows performed more operations independently.

Conclusion

There is a measurable, but small, negative impact of a fellow on a robotic-assisted partial nephrectomy service, which reduces with experience. With appropriate supervision and patient selection, a fellow can be taught robotic-assisted partial nephrectomy without affecting patient safety or treatment outcome.
Rectal foreign body removal: increasing incidence and cost to the NHS
Authors: Bhasin S , Williams JG
Published: May 2023

Introduction

Insertion of foreign objects into the rectum is a well-described phenomenon and not an uncommon referral to the general surgeon on call. Although usually not life-threatening, there can be consequences following migration of the object or perforation of the large bowel. This study looks at the incidence of removal of foreign objects from the rectum over the last decade and the financial burden it presents to the NHS.

Methods

Hospital Episode Statistics for 2010–2019 were used to calculate the number of rectal foreign bodies that required removal in hospital. Data for age groups and genders have been compared.

Results

A total of 3,500 rectal foreign bodies were removed over the course of 9 years. Males accounted for 85.1% of rectal foreign bodies whilst 14.9% were females. This equates to 348 bed-days per annum. Admission peaks were observed in the second and fifth decades of life.

Conclusion

This study shows that the incidence of rectal foreign bodies is higher in men and has been increasing over the period studied. Most foreign bodies can be removed trans-anally with the use of anaesthesia, with only a small proportion of patients requiring hospital stay over 24 hours (mean length of stay = 24 hours). Nearly 400 rectal foreign body removals are performed each year with an annual cost of £338,819, illustrating the effect this has on NHS resources.
Medical negligence in urology: an untapped database
Authors: Whitfield HN
Published: May 2023

Introduction

The aim of this study was to identify the causes of urological litigation in the NHS and to make recommendations how to reduce the burden of litigation to both injured patients and urologists.

Methods

Under the Freedom of Information Act, the National Health Service Resolution (NHSR) was asked to provide the figures for the number of cases of litigation in urology reported between 2010 and 2020.

Results

The number of urological claims more than doubled between 2011 and 2020. Many of the claims that are made result from avoidable errors.

Conclusion

More education is needed, of both urologists in training and consultant urologists, on the causes of errors that lead to litigation and how many of them can be avoided.
Surgical management of advanced pleomorphic dermal sarcoma of the occipital scalp
Authors: Patel KB , Williams JV , Baxter EM , Chengot P , Parmar JD
Published: May 2023

Pleomorphic dermal sarcoma is a rare neoplasm of mesenchymal origin that most commonly affects the head. We describe the presentation of a 61-year-old man with a 10-week history of an exophytic lesion affecting the occipital scalp, demonstrating rapid growth. The final histopathology revealed a completely excised 9cm pleomorphic dermal sarcoma (pT2aN0M0, Stage 3), one of the largest such lesions reported in the literature to date. This patient’s management involved a wide local subperiosteal excision onto the cranium, with a reconstruction with an Integra dermal regeneration template (Integra LifeSciences, Princeton, NJ, USA) and healing with secondary intention. This was mainly due to poorly defined clinical margins on primary excision, the potential for further excision of involved margins (later confirmed as not needed) and the patient’s comorbidities, making a return to theatre for definitive reconstruction undesirable.
Vitamin D repletion in primary hyperparathyroid patients undergoing parathyroidectomy leads to reduced symptomatic hypocalcaemia and reduced length of stay: a retrospective cohort study
Authors: Acharya R , Kopczynska M , Goodmaker C , Mukherjee A , Doran H
Published: May 2023

Introduction

Vitamin D deficiency co-exists with and can confuse the diagnosis of primary hyperparathyroidism (PHPT). Vitamin D replete (VDR) status may prevent significant postparathyroidectomy hypocalcaemia; however, reports from previous studies are conflicting. This study aimed to assess differences in early and/or late postoperative hypocalcaemia and length of stay (LOS) postparathyroidectomy between VDR and vitamin D non-replete (VDNR) PHPT patients.

Methods

This was a retrospective cohort study of a prospectively maintained single surgeon operative database. All records of patients who underwent parathyroidectomy over a four-year period (July 2014 to December 2018) were extracted. Data were collected on vitamin D and corrected calcium levels pre- and postoperatively as well as postoperative complications and LOS.

Results

On presentation, there were 91 (47.9%) VDR and 99 (52.1%) VDNR patients. Following vitamin D therapy there were 148 (77.9%) VDR and 42 (22.1%) VDNR. The multivariate analysis showed that vitamin D status was the only significant factor impacting on the hypocalcaemia symptoms (OR 4.9, 95% CI 1.8–13.7, p = 0.002) and the most significant factor for the calcium supplementation (OR 6.5, 95% CI 2.1–19.4, p = 0.001). Bilateral neck exploration was associated with increased likelihood of transient hypocalcaemia (p = 0.007) but no other post-op complication. Median LOS was significantly shorter for VDR (1 day) versus VDNR (1.5 days) patients (p = 0.001).

Conclusion

There is a statistically significant increased likelihood of postoperative hypocalcaemia symptoms, requirement for calcium supplements and increased LOS in VDNR patients. This study suggests optimising preoperative vitamin D status improves patient experience and could reduce healthcare costs.
Time, cost and carbon-efficiency: a silver lining of COVID era virtual urology clinics?
Authors: Croghan SM , Rohan P , Considine S , Salloum A , Smyth L , Ahmad I , Lynch TH , Manecksha RP
Published: May 2023

Introduction

The COVID-19 pandemic has demanded radical changes in service delivery. Our centre adopted the use of outpatient telemedicine to reduce close-contact interactions between patients and staff. We hypothesised that incidental gains may be associated with this. We evaluated financial, practical and environmental implications of substituting virtual clinics (VCs) for in-person urology outpatient appointments.

Methods

VCs were studied over a 3-month period. Based on patient-reported ‘usual mode of transport’ to the hospital, travel distance, time, petrol and parking costs, and the carbon emissions avoided by virtue of remote consultations were calculated. The underlying symptom/diagnosis and the ‘effectiveness’ of the VC were evaluated.

Results

Of 1,016 scheduled consultations, 736 (72.44%) were conducted by VCs over the study period. VCs resulted in an agreed treatment plan in 98.4% of a representative patient sample. The use of VCs was associated with an overall travel distance saving for patients of 31,038 miles (49,951km) over 3 months, with an average round-trip journey of 93.8 miles (151km) avoided for each rural-dwelling patient and an average financial saving of £25.91 (€28.70) per rural-dwelling car traveller. An estimated 1,257.8 hours of patient time were saved by avoidance of travel and clinic waiting times. Based on car-travelling patients alone, a 6.07-tonne reduction in carbon emissions was achieved with the use of VCs.

Conclusions

In appropriate clinical circumstances, VCs appear to provide efficiency across a number of domains. Future healthcare may involve offering outpatients the option of telemedicine as an alternative to physical attendance.
Giant retroperitoneal liposarcoma surgical management
Authors: Herrera-Almario G , Cabrera LF , Londoño-Schimmer EE , Pedraza M
Published: May 2023

Retroperitoneal liposarcomas are very infrequent retroperitoneal malignant tumours. Most patients complain of palpable abdominal mass and only half present with abdominal pain. With haematogenous spread they can reach, mainly, lungs and liver, but only in 10% of cases. Here we report the presentation and surgical treatment of a giant massive retroperitoneal liposarcoma in a 53-year-old man.
Malpractice litigation and spinal surgery in the National Health Service: a single tertiary-level centre perspective over 12 years
Authors: Quraishi NA , Shetaiwi A , D’Aquino D , Salem K
Published: May 2023

Introduction

Medical malpractice litigation is a major concern for all spine surgeons. Our aim was to evaluate the incidence and burden of successful litigation relating to the management of spinal disorders over 12 years within a UK NHS tertiary-level spinal unit and compare these litigation costs with those of other specialties.

Methods

We obtained all data held by our claims department from its inception in January 2008 to December 2019. We also obtained costs for the total financial burden incurred by our Trust during this period.

Results

In total, there were 83 closed claims involving spinal pathologies. Over 80% of these comprised negligent surgery (n = 28, 34%), delay to diagnose/treat (n = 25, 30%) and negligent care (n = 18, 22%). The vast majority of claims were withdrawn without incurring any cost to the hospital (n = 59, 71%) and only 24 (29%) resulted in successful litigation for the claimant. The total cost of damages for these 24 successful claims was just over £8 million, including legal costs of £2.5 million, out of total litigation costs of £381 million over this period.

Discussion

Fewer than 30% of initial claims against a tertiary spinal surgical referral unit resulted in a successful financial outcome for the claimant. The total costs incurred were just over £8 million, with one-third apportioned to high legal costs, reflecting the complexity of resolving spinal litigation. Our entire legal expenses accounted for only 2% of the total legal bill paid by our hospital over a 12-year period.
Renal cell carcinoma with duplication of inferior vena cava
Authors: Yusof MR , Fahmey O , Lee CKS , Azli MZ Saiful , Arunasalam AP , Khairul-Asri MG
Published: May 2023

Renal cell carcinoma (RCC) has been shown to cause venous migration in the inferior vena cava (IVC). It is very important for preoperative imaging to be carried out, which will decide the surgical approach for the patient. Duplication of IVC is an uncommon anomaly. We report a case of RCC with duplication of IVC.
Avoiding appendectomy with an ultrasound probe
Authors: Oikonomou P , Nikolaou C , Chrisafis I , Romanidis K , Tsalikidis C , Pitiakoudis M
Published: May 2023

Acute appendicitis is common in patients with right lower quadrant pain and affects all gender and age groups. Because clinical diagnosis of patients with right lower quadrant pain remains a challenge to emergency physicians and surgeons, imaging is of major importance. Ultrasound has well-established direct and indirect signs for diagnosing acute appendicitis and revealing the presence of an appendicolith. Appendectomy, which can be either open or laparoscopic, constitutes the basic treatment. However, the need for an appendectomy is debatable, particularly in high-risk patients. We report the case of a 42-year-old woman with no relevant medical history who was sent to the emergency department by her family physician with right lower quadrant pain of 18 hours’ duration. Using ultrasound, the emergency physicians identified, inside the appendix, a 0.6cm appendiceal faecolith, migration of which was eventuated by manipulation of the ultrasound probe. The patient was then successfully treated non-operatively without any antibiotic prescription. Despite its rarity, migration of an appendiceal faecolith is possible. When migration of an appendicolith is perhaps actualised spontaneously or by ultrasound probe manipulation, the likelihood of an appendectomy decreases dramatically. This hypothesis provides patients who present an appendiceal faecolith with an alternative treatment approach that will lead to the avoidance of surgery, minimise morbidity and reduce hospitalisation costs.
To block, or not to block … is it still the question? Effectiveness of alpha- and beta-blockade in phaeochromocytoma surgery: an institutional analysis
Authors: Van Den Heede K , Paspala A , Chander N , Chidambaram S , Wernig F , Todd JF , DiMarco AN , Palazzo FF
Published: May 2023

Introduction

Phaeochromocytomas/paraganglioma (PPGL) surgery was historically associated with significant risks of perioperative complications. The decreased mortality (<3.0%) had been attributed in part to optimal preoperative alpha-blockade. The value of alpha-blockade in decreasing morbidity is being challenged. The aim of our study is to present an institutional experience of preoperative alpha-blocking of PPGL and its effect on cardiovascular stability and postoperative morbidity.

Methods

A retrospective study using data from our institutional database was conducted. All patients undergoing adrenalectomy for PPGL from October 2011 to September 2020 were included. All patients were routinely alpha-blocked. Intraoperative cardiovascular instability (ICI) was assessed through number of systolic blood pressure (SBP) episodes >160mmHg, SBP <90mmHg, the need for vasoactive drugs and volume of intraoperative crystalloids administered. Morbidity was also evaluated.

Results

A total of 100 consecutive patients undergoing surgery were identified of whom 53 patients had complete anaesthetic records available for analysis. Thirty-two patients (60%) had at least one episode with an SBP >160mmHg. Nine (17%) cases had no intraoperative hypotensive episodes, while 3 (6%) patients had >10 intraoperative episodes of an SBP <90mmHg. Twenty-one (40%) patients received vasoactive drugs during surgery. The median volume of intraoperative crystalloids was 2 litres (1–4). Postoperatively, no patient experienced cardiovascular complications, including arrhythmia or myocardial ischaemia. Only two were admitted to an intensive care unit (ICU) and one 30-day readmission occurred.

Conclusions

Cardiac instability remained significant in PPGL surgery despite optimal alpha- and beta-blockade. While omitting blockade would appear empirically questionable, a randomised controlled trial (RCT) of surgery with and without alpha-blockade will provide an answer.
Small bowel intussusception and concurrent jejunal polyp with neoplastic transformation: a new diagnosis of Peutz–Jeghers syndrome
Authors: Hudson VE , Rooney S , Pursglove S , Bhojwani D , Gourgiotis S
Published: May 2023

Peutz–Jeghers syndrome (PJS) is a rare hereditary disease characterised by hyperpigmentation of the oral mucosa and gastrointestinal hamartomatous polyps. We report a case of a 27-year-old man who presented with a 5-day history of epigastric pain and rectal bleeding. Computed tomography suggested small bowel obstruction secondary to ileocolic intussusception and an incidental polyp in the mid jejunum. The patient underwent exploratory laparotomy during which right hemicolectomy and small bowel resection were performed. Histology from surgical specimens revealed Peutz–Jeghers polyps, one of which had low-grade dysplasia. This case emphasises that although rare, adults with PJS can present with intussusception. Also illustrated is the extremely rare possibility of concurrent polyps occurring in different parts of the bowel with neoplastic transformation. Intussusception is a challenge to diagnose because the presentation is often non-specific. Clinical history-taking and physical examination along with prompt axial imaging is important for the diagnosis. Careful examination of the bowel and polypectomy during laparotomy may prevent neoplastic transformation and short bowel syndrome.
A simple intervention to improve the use of postoperative antibiotics and intra-abdominal drains in appendicectomy patients
Authors: Sorooshian P , Ward R , Sandison AJP
Published: May 2023

Introduction

Appendicitis remains the most common intra-abdominal surgical emergency, yet many patients receive postoperative antibiotics and intra-abdominal drains against recommended guidelines. This study assesses the impact of an educational poster on the appropriate use of postoperative antibiotics and intra-abdominal drains in appendicectomy patients.

Methods

Patients who underwent an appendicectomy between January and April 2019 (‘Poster absent’ group) as well as between November 2019 and February 2020 (‘Poster present’ group) were identified. Data were collected on patient demographics, the presence of complicating features (ie appendiceal abscesses, intraperitoneal pus, gangrene and/or perforation) as well as the use of postoperative antibiotics and intra-abdominal drains in accordance with World Society of Emergency Surgery guidelines.

Results

One hundred and thirty patients were included in the ‘Poster absent’ (73 patients) and ‘Poster present’ (57 patients) groups. After introducing the educational poster there was a significant reduction in the use of postoperative antibiotics (60.5% to 13.8%; p<0.0001) and an insignificant reduction in intra-abdominal drain use (15.2% to 13.2% p>0.05) that were contraindicated in simple appendicitis. There was a significant improvement in the use of postoperative antibiotics (71.9% to 100%; p=0.0019) and an insignificant increase in intra-abdominal drain use (58.8% to 64.3%; p>0.05) that were indicated in complicated appendicitis. The rates of wound infection (4.10% to 0%; p=0.2556) and ileus/obstruction (5.48% to 1.75%; p=0.3846) also reduced.

Conclusion

This small study demonstrated that a simple and appropriately targeted intervention of an educational poster can significantly improve and reduce variation in the management of appendicectomy patients and may reduce postoperative complications.
Oesophageal carcinosarcoma: a rare neoplasm of the oesophagus
Authors: Aruni A , Nagaraj SS , Deivasigamani S , Chowdhury A , Kumar H , Chatterjee D
Published: May 2023

Oesophageal carcinosarcoma (OCS) is a rare oesophageal cancer, expressing both carcinomatous and sarcomatous elements. Although believed to have a better prognosis, no standard guidelines exist for its diagnosis and management. We report a case of a 60-year male presenting with progressive dysphagia and weight loss. Endoscopy and contrast-enhanced computed tomography of the chest revealed a large polypoidal intraluminal growth at the mid-oesophagus. Endoscopic biopsy revealed a sarcoma of the oesophagus. The patient underwent McKeown minimally invasive oesophagectomy. Final histopathology was suggestive of OCS. Postoperatively, the patient received adjuvant chemoradiation. At 20-month follow-up, he was asymptomatic with no radiological evidence of recurrence.
A comparison of cytoreductive and non-cytoreductive management strategies for nephron-sparing approaches to tumours in solitary kidneys
Authors: Nayak A , Piedad J , Wagh Y , Nathan P , Sharma A , Pullar B , Hanbury D , Adshead J
Published: May 2023

Introduction

Tumours in a solitary kidney pose challenges in management. Metastatic tumours and those in difficult locations complicate treatment further. The advent of immunotherapy has shed new light on the management of such tumours. We present a series of three cases treated with nephron-sparing surgery following neoadjuvant immunotherapy and compare the outcomes with patients who underwent robotic partial nephrectomy in a solitary kidney.

Methods

We present the outcomes of three patients with solitary kidney tumours who underwent delayed nephron-sparing surgery following good response to immunotherapy. All patients had solitary kidney following a previous nephrectomy, two of which were nonmetastatic but, due to size/location, not amenable to primary treatment; the third patient had metastatic disease and responded to immunotherapy. Two patients underwent robotic partial nephrectomy and one opted for cryotherapy. We compared the preoperative, intraoperative and postoperative parameters of the two patients who underwent robotic cytoreductive partial with patients who underwent robotic partial nephrectomy in a solitary kidney.

Results

Out of 231 partial nephrectomy patients in our centre, 2 underwent cytoreductive partial nephrectomy and 5 underwent solitary partial nephrectomy. There was no statistically significant difference in the patient demographics in the two groups. Patients in both groups had comparable operative time, warm ischaemia time, blood loss and length of stay. Two of the five patients in the non-cytoreductive robotic partial nephrectomy had Clavien Dindo 1 complications compared with one patient in the robotic cytoreductive partial nephrectomy group. This was not statically significant.

Conclusion

Neoadjuvant immunotherapy can play a valuable role in shrinking renal tumours in solitary kidneys to facilitate robotic partial nephrectomies. There were no significant differences in the intra- and postoperative parameters in patients who underwent cytoreductive partial nephrectomy when compared with patients undergoing robotic solitary partial nephrectomy.
The new Future of Surgery Innovation Hub needs your help
Authors: Kerstein Ryan
Published: May 2023

Our Editor discusses the new Future of Surgery Innovation Hub, and how the College is pioneering the advancement of surgical training.
‘Fit to set before the King’: the secrets of Queen Henrietta Maria’s kitchen
Authors: Blakey Emily
Published: May 2023

We take a look at historic guides to living that are fit for a king (or queen).
Assessing the impact of surgical hubs
Authors: Holloway Victoria
Published: May 2023

Our Political Editor discusses the benefits that surgical hubs have had on patients and the surgical backlog.
Should clinical coding be taught to junior doctors and medical students?
Authors: Shamim S , Ansari SA , Barter R , Javed MA
Published: May 2023

Introduction

Most medical schools and foundation curricula do not cover understanding of NHS finances and clinical coding. However, foundation doctors produce daily clinical documentation and discharge summaries, especially in surgical departments. We evaluated the effect of a simple teaching session for final year medical students’ understanding of NHS finances and clinical coding.

Methods

A simple questionnaire was distributed to 28 final year medical students. This assessed each student’s knowledge of clinical coding and NHS finances. A short presentation on this topic was delivered to this same group of students, following which the questionnaire was repeated. Post-session feedback was also collected.

Results

A significant gap in knowledge was found regarding NHS finances and clinical coding in the pre-session questionnaire. Only half (54%) of the medical students thought that junior doctors should be responsible for clinical coding; this increased to 91% after the teaching session. When asked whether it would be relevant to learn principles of clinical coding before foundation training, 64% agreed prior to the session, rising to 91% afterwards. The vast majority (95%) of participants agreed after the teaching session that an understanding of clinical coding could lead to an improvement in the quality of clinical documentation.

Conclusions

Most medical students thought it was important for doctors to understand the basic principles of NHS finances, the NHS budget and clinical coding. They agreed that clinical documentation could also be improved if doctors had a better understanding of clinical coding.
'It is never too late to be who you might have been’
Authors: Crean StJohn
Published: May 2023

Our editor reflects on the year and the importance of pursuing your passion.
Comparative Analysis of Wind Energy Potential with Nakagami and Weibull Distribution Methods for Wind Turbine Planning
Authors: Suriadi Suriadi , Nabilah Muna , Zainal Muzakir , Yanis Muhammad , Marwan Marwan , Hafidh Hafidh , Affan Muzailin
Published: May 2023

Wind energy is renewable energy used as an energy source for wind power plants (PLTB). The most common distribution method used to model wind speed distribution data is the Weibull distribution. The Nakagami distribution has begun to be widely used in several studies to model wind speed distribution data. The Nakagami distribution is considered an alternative to the Weibull distribution in modeling wind speed distribution data. This study aims to compare the distribution of Nakagami and Weibull in analyzing wind power potential and calculating the resulting Wind Energy Production (WEP), using wind speed distribution data from both distributions in Kuta Raja, Banda Aceh and Lhoknga, Aceh Besar. The wind speed data used is satellite data (secondary data) downloaded via windguru.cz, with the most stable wind speed being a wind speed of 3-5 m/s. The value of wind power potential at the Kuta Raja location, Banda Aceh was obtained at 64.16% with the Nakagami distribution and 62.73% with the Weibull distribution, and 73.60% with the Nakagami distribution and 73.28% at the Lhoknga location, Aceh Besar. The comparison of these two distributions produces a Weibull distribution that is superior to the Nakagami distribution for both locations, where the Weibull distribution has a smaller error value and produces a WEP value that is in accordance with the actual/observable data compared to the Nakagami distribution. In this study, the Nakagami distribution has results that make this distribution an alternative or comparison to the Weibull distribution in distributing wind speed data with further research.
Fast and rigorous optical simulation of periodically corrugated light-emitting diodes based on a diffraction matrix method
Authors: Park Chanhyung , Shin Jeongmin , Kim Sanmun , Lee Songju , Park Juho , Park Jaehyeok , Park Sehong , Yoo Seunghyup , Jang Min Seok
Published: May 2023

Increasing the light extraction efficiency has been widely studied for highly efficient organic light-emitting diodes (OLEDs). Among many light-extraction approaches proposed so far, adding a corrugation layer has been considered a promising solution for its simplicity and high effectiveness. While the working principle of periodically corrugated OLEDs can be qualitatively explained by the diffraction theory, dipolar emission inside the OLED structure makes its quantitative analysis challenging, making one rely on finite-element electromagnetic simulations that could require huge computing resources. Here, we demonstrate a new simulation method, named the diffraction matrix method (DMM), that can accurately predict the optical characteristics of periodically corrugated OLEDs while achieving calculation speed that is a few orders of magnitude faster. Our method decomposes the light emitted by a dipolar emitter into plane waves with different wavevectors and tracks the diffraction behavior of waves using diffraction matrices. Calculated optical parameters show a quantitative agreement with those predicted by finite-difference time-domain (FDTD) method. Furthermore, the developed method possesses a unique advantage over the conventional approaches that it naturally evaluates the wavevector-dependent power dissipation of a dipole and is thus capable of identifying the loss channels inside OLEDs in a quantitative manner.