Cherenkov radiation emitted by ultrafast laser pulses and the generation of coherent polaritons

We report on the generation of coherent phonon polaritons in ZnTe, GaP and LiTaO$_{3}$ using ultrafast optical pulses. These polaritons are coupled modes consisting of mostly far-infrared radiation and a small phonon component, which are excited through nonlinear optical processes involving the Raman and the second-order susceptibilities (difference frequency generation). We probe their associated hybrid vibrational-electric field, in the THz range, by electro-optic sampling methods. The measured field patterns agree very well with calculations for the field due to a distribution of dipoles that follows the shape and moves with the group velocity of the optical pulses. For a tightly focused pulse, the pattern is identical to that of classical Cherenkov radiation by a moving dipole. Results for other shapes and, in particular, for the planar and transient-grating geometries, are accounted for by a convolution of the Cherenkov field due to a point dipole with the function describing the slowly-varying intensity of the pulse. Hence, polariton fields resulting from pulses of arbitrary shape can be described quantitatively in terms of expressions for the Cherenkov radiation emitted by an extended source. Using the Cherenkov approach, we recover the phase-matching conditions that lead to the selection of specific polariton wavevectors in the planar and transient grating geometry as well as the Cherenkov angle itself. The formalism can be easily extended to media exhibiting dispersion in the THz range. Calculations and experimental data for point-like and planar sources reveal significant differences between the so-called superluminal and subluminal cases where the group velocity of the optical pulses is, respectively, above and below the highest phase velocity in the infrared.Comment: 13 pages, 11 figure

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

A Platform (Authorships.org) for the Objective Qualification and Order of Academic Authorship in Medical and Science Journals: Development and Evaluation Study Using the Design Science Research Methodology

Background: The qualification and order of authorship in scientific manuscripts are the main disputes in collaborative research work. Objective: The aim of this project was to develop an open-access web-based platform for objective decision-making of authorship qualification and order in medical and science journals. Methods: The design science process methodology was used to develop suitable software for authorship qualification and order. The first part of the software was designed to differentiate between qualification for authorship versus acknowledgment, using items of the recommendations of the International Committee of Medical Journal Editors. The second part addressed the order of authorship, using the analytical hierarchy process for objective multiple criteria decision-making and ranking. The platform was evaluated qualitatively (n=30) and quantitatively (n=18) using a dedicated questionnaire, by an international panel of medical and biomedical professionals and research collaborators worldwide. Results: Authorships.org represents an open-access software compatible with all major platforms and web browsers. Software usability and output were evaluated and presented for 3 existing clinical and biomedical research studies. All 18 international evaluators felt that the Authorships.org platform was easy to use or remained neutral. Moreover, 59% (n=10) were satisfied with the software output results while the rest were unsure, 59% (n=10) would definitely use it for future projects while 41% (n=7) would consider it, 94% (n=16) felt it may prove useful to eliminate disputes regarding authorship, 82% (n=14) felt that it should become mandatory for manuscript submission to journals, and 53% (n=9) raised concerns regarding the potential unethical use of the software as a tool. Conclusions: Authorships.org allows transparent evaluation of authorship qualification and order in academic medical and science journals. Objectified proof of authorship contributions may become mandatory during manuscript submission in high-quality academic journals. © 2022 JMIR Publications Inc.. All Rights Reserved

Dose-dependent effects of recombinant human interleukin-6 on the pituitary-testicular axis

Inflammatory cytokines are soluble mediators of immune function that also regulate intermediate metabolism and several endocrine axes. To examine the effects of interleukin-6 (IL-6), the main circulating cytokine, on the hypothalamic-pituitary-testicular axis in men, we performed dose-response studies of recombinant human IL-6 (rHuIL-6) in normal volunteers. Increasing single doses of IL-6 (0.1, 0.3, 1.0, 3.0, and 10.0 $mg/kg body weight) were injected subcutaneously into 15 healthy male volunteers (3 at each dose) in the morning. We measured the circulating levels of testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), and sex hormone binding globulin (SHBG) at baseline and then at 24 h, 48 h, and 7 days after the IL-6 injection. LH and FSH levels were also measured half-hourly for the first 4 h after the IL-6 injection. All IL-6 doses were tolerated well and produced no significant adverse effects. Mean peak plasma IL-6 levels achieved after IL-6 administration were 8 ± 1, 22 ± 5, 65 ± 22, 290 ± 38, and 4050 ± 149 pg/ml, respectively for the five doses. We observed no significant changes in plasma testosterone levels after the two smaller IL-6 doses. The three higher IL-6 doses, however, caused significant decreases in testosterone levels by 24 h, which persisted at 48 h and returned to baseline by 7 days. The higher testosterone suppression was after the 3.0 μg/kg dose, making the dose- response curve bell-shaped. There also appeared to be small but not significant increases in LH levels after the three higher IL-6 doses, which were not acute and seemed to follow temporally the testosterone decreases. The concurrent plasma levels of FSH and SHBG were not appreciably affected by any IL-6 dose. In conclusion, subcutaneous IL-6 administration, which caused acute elevations in circulating IL-6 levels of a similar magnitude to those observed in severe inflammatory and noninflammatory stress, induced prolonged suppression in testosterone levels in healthy men without apparent changes in gonadotropin levels. This suggests that IL-6 might induce persistent testicular resistance to LH action or suppression of Leydig cell steroidogenesis or both, with potential adverse effects on male reproductive function

Intrahepatic cholangiocarcinoma: Limitations for resectability, current surgical concepts and future perspectives

Intrahepatic cholangiocarcinoma (iCCA) is the second most common hepatic malignancy and its incidence has been shown to increase significantly during the past decades. Complete surgical resection is currently acknowledged as the only curative treatment option able to provide adequate long-term outcomes. We herein review technical, functional and oncologic limitations for resectability, discuss current surgical aspects as well as highlight the fields in which future research and practice should focus on in order to ameliorate long-term outcomes in patients with iCCA. © 2020 Elsevier Ltd, BASO ~ The Association for Cancer Surgery, and the European Society of Surgical Oncolog

Poor level of agreement on the management of postoperative pancreatic fistula: results of an international survey

OBJECTIVES: The occurrence of postoperative pancreatic fistula (POPF) is the main cause of severe complications, including death, after pancreatic surgery. This study was conduced to evaluate current practice in the management of POPF after Whipple surgery and distal pancreatectomy (DP). METHODS: An online survey endorsed by the European-African Hepato-Pancreato-Biliary Association (E-AHPBA) was conducted among surgical departments active in pancreatic surgery. A total of 108 centres were contacted by e-mail. The survey focused on the use and timing of drainage, nutrition strategies, provision of somatostatin and antibiotic therapies, imaging strategy and indications for reoperation when POPF is diagnosed after pancreatic surgery. RESULTS: A total of 55 centres (51%) completed the survey. Overall, responses showed poor agreement among centres (Fleiss' kappa: <0.40) on 89% of items after Whipple surgery and 78% of items after DP. There was very poor or no agreement (Fleiss' kappa: <0.1) on postoperative strategies for the management of nutrition and use of somatostatin after both procedures. In the event of POPF, 42% of centres used total oral nutrition and 22% used somatostatin after Whipple surgery, and 71% used total oral nutrition and 31% used somatostatin after DP. There were significant disagreements between units conducting, respectively, more and fewer than 50 Whipple procedures per year on drain removal after DP, and imaging strategy and patient discharge after Whipple surgery and DP. CONCLUSIONS: This survey discloses important disagreements worldwide regarding the management of POPF after both Whipple surgery and DP. The standardized management of POPF would better facilitate the comparison of outcomes in future trials

The use of nasojejunal nutrition in patients with chronic pancreatitis

CONTEXT: Abdominal pain, malabsorption and diabetes all contribute to a negative impact upon nutritional status in chronic pancreatitis and no validated standard for the nutritional management of patients exists. OBJECTIVE: To assess the effect of nasojejunal nutrition in chronic pancreatitis patients. DESIGN: All consecutive chronic pancreatitis patients fed via the nasojejunal route between January 2004 and December 2007 were included in the study. Patients were assessed via retrospective review of case notes. RESULTS: Fifty-eight chronic pancreatitis patients (35 males, 23 females; median age 46 years) were included. Patients were discharged after a median of 14 days and nasojejunal nutrition continued for a median of 47 days. Forty-six patients (79.3%) reported resolution of their abdominal pain and cessation of opioid analgesia intake over the study period and median weight gain at 6 weeks following nutritional cessation was +1 kg (range -24 to +27 kg; P=0.454). Twelve (20.7%) patients reported recurrence of their pain during the follow-up period and complications were both minor and infrequent. Significant improvements were noted in most blood parameters measured, including: sodium (from 134.8 to 138.1 mEq/L; P<0.001); urea (from 3.4 to 5.1 mmol/L; P<0.001); creatinine (from 58.3 to 60.3 micromol/L; P<0.001); corrected calcium (from 2.24 to 2.35 mmol/L; P=0.018); albumin (from 34.5 to 38.7 g/L; P=0.002); CRP (from 73.0 to 25.5 mg/L; P=0.006); and haemoglobin (from 11.8 to 12.4 g/dL; P=0.036). CONCLUSION: Nasojejunal nutrition, commenced in hospital and continued at home, is safe, efficacious and well tolerated in patients with severe chronic pancreatitis and is effective in helping to relieve pain and diminish analgesic requirements

Four-corner fusion of the wrist: clinical and radiographic outcome of 31 patients

Background: Four-corner fusion is a rational surgical option for the management of degenerative conditions of the wrist. Most related studies have compared four-corner fusion with scaphoid excision or proximal row carpectomy, with a variety of reported results. To enhance the literature, we performed this study to evaluate a series of patients with degenerative conditions of the wrist treated with four-corner fusion using 3 surgical techniques and to discuss the clinical and radiographic outcome of the patients. Materials and methods: We retrospectively studied 31 patients (24 men, 7 women; mean age, 43 years; 9 heavy manual laborers) who underwent four-corner fusion of their wrists for degenerative conditions from 2005 to 2015. Internal fixation was done using multiple Kirschner wires (14 patients), headless compressive screws (8 patients), or a circular plate (9 patients). Mean follow-up was 4 years (1–11 years). We evaluated the clinical outcome with the Patient-Rated Wrist Evaluation (PRWE) score and fusion with radiographs. Results: All patients experienced improvement of their pain, function, range of motion and grip strength (p &lt; 0.05). Twenty-three patients (74 %) reported no pain, and eight patients reported mild, occasional pain. Twenty-one patients (68 %) were able to do usual and specific activities. Mean wrist motion improved to 70 % and mean grip strength improved to 85 % of opposite wrist. Two heavy manual labor patients requested a job modification because of wrist impairment. Radiographs of the wrist showed fusion of all fused joints in 28 (90.3 %) patients and partial fusion in three patients (9.7 %). No patient with partial fusion required a reoperation for symptomatic nonunion until the period of this study. Three patients experienced complications (10 %). Two patients treated with a circular plate experienced complex regional pain syndrome and painful implant impingement; another patient treated with Kirschner wires and headless compression screws experienced radiolunate arthritis from impingement of the lunate screw to the radius. Conclusions: Four-corner fusion is a reliable limited wrist fusion technique that provides pain relief, grip strength and satisfactory range of motion in patients with degenerative conditions of the wrist. Partial union is more common with Kirschner wire fixation and complications are more common with circular plate fixation. © 2016, Springer-Verlag France