Design Concept for Key Parameters of Reverse Conducting GCT

Presented is design concept for key parameters o f the reverse conducting gate commutated thyristor (RC-GCT),such as the thickness and concentration of n-base region and the transparent anode region,and the wi dth of separation region between asymmetric GCT and PIN diode.A structure model of the RC-GCT is set up based on the design concept and its characteristics are analyzed.The simulation results show the design concept is reasonable.

Monitoring of ducting by using a ground-based GPS receiver

In this paper,we describe the estimation of low-altitude refractivity structure from simulation and real ground-based GPS delays.The vertical structure of the refractive environment is modeled using three parameters,i.e.,duct height,duct thickness,and duct slope.The refractivity model is implemented with a priori constraints on the duct height,thickness,and strength,which might be derived from soundings or numerical weather-prediction models.A ray propagation model maps the refractivity structure into a replica field.Replica fields are compared with the simulation observed data using a squarederror objective function.A global search for the three environmental parameters is performed using a genetic algorithm.The inversion is assessed by comparing the refractivity profiles from the radiosondes to those estimated.This technique could provide near-real-time estimation of the ducting effect.The results suggest that ground-based GPS provides significant atmospheric refractivity information,despite certain fundamental limitations of ground-based measurements.Radiosondes are typically launched just a few times daily.Consequently,estimates of temporally and spatially varying refractivity that assimilate GPS delays could substantially improve over-estimates caused by using radiosonde data alone.

Estimation of co-channel interference between cities caused by ducting and turbulence

With the rapid development of the fifth-generation(5 G)mobile communication technology,the application of each frequency band has reached the extreme,causing mutual interference between different modules.Hence,there is a requirement for detecting filtering and preventing interference.In the troposphere,over-the-horizon propagation occurs in atmospheric ducts and turbulent media.The effects of both ducting and turbulence can increase the probability of occurrence of long-distance co-channel interference(CCI),in turn,severely affecting the key performance indicators such as system access,handover and drop.In the 5 G era,to ensure communication channels and information security,CCI must be reduced.This paper introduces a scattering parabolic equation algorithm for calculating signal propagation in atmospheric ducts on irregular terrain boundaries.It combines Hitney’s radio physical optical model and Wagner’s nonuniform turbulent scattering model for calculating the tropospheric scattering in an evaporation duct or a surface-based duct.The new model proposes a tropospheric scattering parabolic equation algorithm for various tropospheric duct environments.Finally,as a specific case,the topographical boundaries between several cities in the East China Plain were considered,and the over-the-horizon propagation loss was simulated for various ducting and turbulent environments.The simulation results were used to evaluate whether CCI would occur between cities in a specific environment.

Response letter to “Acute cholangitis: Does malignant biliary obstruction vs choledocholithiasis etiology change the outcomes?” with imaging aspects

Radiological imaging findings may contribute to the differentiation of malignant biliary obstruction from choledocholithiasis in the etiology of acute cholangitis.

Removal of intrahepatic bile duct stone could reduce the risk of cholangiocarcinoma: A single-center retrospective study in South Korea

BACKGROUND Intrahepatic duct(IHD)stones are among the most important risk factors for cholangiocarcinoma(CCC).Approximately 10%of patients with IHD stones develop CCC;however,there are limited studies regarding the effect of IHD stone removal on CCC development.AIM To investigate the association between IHD stone removal and CCC development.METHODS We retrospectively analyzed 397 patients with IHD stones at a tertiary referral center between January 2011 and December 2020.RESULTS CCC occurred in 36 of the 397 enrolled patients.In univariate analysis,chronic hepatitis B infection(11.1%vs 3.0%,P=0.03),carbohydrate antigen 19-9(CA19-9,176.00 vs 11.96 II/mL,P=0.010),stone located in left or both lobes(86.1%vs 70.1%,P=0.042),focal atrophy(52.8%vs 26.9%,P=0.001),duct stricture(47.2%vs 24.9%,P=0.004),and removal status of IHD stone(33.3%vs 63.2%,P<0.001)were significantly different between IHD stone patients with and without CCC.In the multivariate analysis,CA19-9>upper normal limit,carcinoembryonic antigen>upper normal limit,stones located in the left or both lobes,focal atrophy,and complete removal of IHD stones without recurrence were independent factors influencing CCC development.However,the type of removal method was not associated with CCC risk.CONCLUSION Complete removal of IHD stones without recurrence could reduce CCC risk.

Atmospheric Ducting Effect in Wireless Communications:Challenges and Opportunities

Atmospheric ducting has a significant impact on electromagnetic wave propagation.Radio signals that are trapped and guided by the atmospheric duct can travel a much longer distance over the horizon with lower attenuation since the signal power does not spread isotropically through the atmosphere.Atmospheric ducting brings both challenges and opportunities to wireless communications.On one hand,the signals propagating in the atmospheric duct may interfere with a receiver far away as remote co-channel interference.On the other hand,a point-to-point link can be established directly through the atmospheric duct to enable beyond line-of-sight communications.In this article,the formation of the atmospheric duct and its effects on radio wave propagation are first overviewed.Then solutions and standardization activities in the 3rd Generation Partnership Project(3GPP)to mitigate atmospheric duct induced remote interference are presented.Finally,the applications and design challenges of atmospheric duct enabled beyond line-of-sight communications are reviewed and future research directions are suggested.

Undifferentiated high-grade pleomorphic sarcoma of the common bile duct:A case report and review of literature

BACKGROUND Undifferentiated pleomorphic sarcoma(UPS)is a rare malignant mesenchymal tumor with a poor prognosis.It mainly occurs in the extremities,trunk,head and neck,and retroperitoneum regions.Owing to the lack of specific clinical manifestations and imaging features,UPS diagnosis mainly depends on pathological and immunohistochemical examinations for exclusive diagnosis.Here we report an extremely rare case of high-grade UPS in the common bile duct(CBD).There are limited available data on such cases.CASE SUMMARY A 70-year-old woman was admitted to our department with yellow eyes and urine accompanied by upper abdominal distending pain for 2 wk.Her laboratory data suggested significantly elevated hepatorenal function levels.The imaging data revealed calculous cholecystitis,intrahepatic and extrahepatic bile duct dilation with extrahepatic bile duct calculi,and a space-occupying lesion at the distal CBD.After endoscopic biliary stenting and symptomatic support therapy,CBD exploration and biopsy were performed.The frozen section indicated malignant spindle cell tumor of the CBD mass,and further radical pancreaticoduodenectomy was performed.Finally,the neoplasm was diagnosed as a high-grade UPS combined with the light-microscopic morphology and immunohistochemical results.CONCLUSION This extremely rare case highlighted the need for increasing physicians'vigilance,reducing the odds of misdiagnosis,and providing appropriate treatment strategies.

Mirizzi syndrome:Problems and strategies

Mirizzi syndrome is a serious complication of gallstone disease.It is caused by the impacted stones in the gallbladder neck or cystic duct.One of the features of Mirizzi syndrome is severe inflammation or dense fibrosis at the Calot’s triangle.In our clinical practice,bile duct,branches of right hepatic artery and right portal vein clinging to gallbladder infundibulum are often observed due to gallbladder infundibulum adhered to right hepatic hilum.The intraoperative damage of branches of right hepatic artery occurs more easily than that of bile duct,all of which are hidden pitfalls for surgeons.Magnetic resonance cholangiopancreatography(MRCP)and endoscopic retrograde cholangiopancreatography(ERCP)are the preferable tools for the diagnosis of Mirizzi syndrome.Anterograde cholecystectomy in Mirizzi syndrome is easy to damage branches of right hepatic artery and bile duct due to gallbladder infundibulum adhered to right hepatic hilum.Subtotal cholecystectomy is an easy,safe and definitive approach to Mirizzi syndrome.When combined with the application of ERCP,a laparoscopic management of Mirizzi syndrome by well-trained surgeons is feasible and safe.The objective of this review was to highlight its existing problems:(1)low preoperative diagnostic rate,(2)easy to damage bile duct and branches of right hepatic artery,and(3)high concomitant gallbladder carcinoma.Meanwhile,the review aimed to discuss the possible therapeutic strategies:(1)to enhance its preoperative recognition by imaging findings,and(2)to avoid potential pitfalls during surgery.

Diseases of bile duct in children

Several diseases originate from bile duct pathology.Despite studies on these diseases,certain etiologies of some of them still cannot be concluded.The most common disease of the bile duct in newborns is biliary atresia,whose prognosis varies according to the age of surgical correction.Other diseases such as Alagille syndrome,inspissated bile duct syndrome,and choledochal cysts are also time-sensitive because they can cause severe liver damage due to obstruction.The majority of these diseases present with cholestatic jaundice in the newborn or infant period,which is quite difficult to differentiate regarding clinical acumen and initial investigations.Intraoperative cholangiography is potentially necessary to make an accurate diagnosis,and further treatment will be performed synchronously or planned as findings suggest.This article provides a concise review of bile duct diseases,with interesting cases.

A Review of Type 1 and Type 2 Intraductal Papillary Neoplasms of the Bile Duct

Intraductal papillary neoplasm of the bile duct(IPNB)is a heterogeneous disease similar to intraductal papillary mucinous neoplasm of the pancreas.These lesions have been recognized as one of the three major precancerous lesions in the biliary tract since 2010.In 2018,Japanese and Korean pathologists reached a consensus,classifying IPNBs into type l and type 2 IPNBs.IPNBs are more prevalent in male patients in East Asia and are closely related to diseases such as cholelithiasis and schistosomiasis.From a molecular genetic perspective,IPNBs exhibit early genetic variations,and different molecular pathways may be involved in the tumorigenesis of type 1 and type 2 IPNBs.The histological subtypes of IPNBs include gastric,intestinal,pancreaticobiliary,or oncocytic subtypes,but type 1 IPNBs typically exhibit more regular and well-organized histological features than type 2 IPNBs and are more commonly found in the intrahepatic bile ducts with abundant mucin.Due to the rarity of these lesions and the absence of specific clinical and laboratory features,imaging is crucial for the preoperative diagnosis of IPNB,with local bile duct dilation and growth along the bile ducts being the main imaging features.Surgical resection remains the optimal treatment for IPNBs,but negative bile duct margins and the removal of lymph nodes in the hepatic hilum significantly improve the postoperative survival rates for patients with IPNBs.

Nasal flap preservation in endoscopic dacryocystorhinostomy for nasolacrimal duct obstruction

AIM:To compare surgical outcomes between the conventional endoscopic dacryocystorhinostomy(DCR)and a modified endoscopic DCR for the treatment of nasolacrimal duct obstruction(NLDO),and evaluate factors associated with the surgical success rate.METHODS:Medical records of patients who underwent primary DCR surgery between January 2016 and July 2020 at the Otorhinolaryngology Department of Eye and Ear International Hospital,Lebanon were reviewed.RESULTS:The study group consisted of 50 consecutive modified endoscopic DCR and the control group consisted of 138 consecutive conventional endoscopic DCR.The success rates at 1y were 98.0%(49 out of 50)for modified DCR,significantly higher compared to 84.8%(117/138)for the conventional DCR;there was no significant difference in the success rate throughout the years in terms of both surgical techniques.The modified surgery vs traditional[adjusted odds ratio(aOR)=14.96]and having an adjunctive septoplasty surgery vs not(aOR=3.99)were significantly associated with higher odds of success.CONCLUSION:Mucosal flap preservation and apposition shows significant improvement in the surgical success rate.Moreover,there is no statistically significant difference found in terms of complication rate and mean operative time between the conventional and the modified techniques.

Is there a place for endoscopic management in postcholecystectomy iatrogenic bile duct injuries?

In this editorial we comment on the article by Emara et al published in the recent issue of the World Journal of Gastrointestinal Surgery.Previously,surgery was the primary treatment for bile duct injuries(BDI).The treatment of BDI has advanced due to technological breakthroughs and minimally invasive procedures.Endoscopic and percutaneous treatments have largely supplanted surgery as the primary treatment for most instances in recent years.Patient management,including the specific technique,is typically impacted by local knowledge and the kind and severity of the injury.Endoscopic therapy is a highly successful treatment for postoperative benign bile duct stenosis and offers superior long-term outcomes compared to surgical correction.Based on the damage features of BDI,therapeutic options include endoscopic duodenal papillary sphincterotomy,endoscopic nasobiliary drainage,and endoscopic biliary stent implantation.

Removal of intrahepatic bile duct stone could reduce the risk of cholangiocarcinoma

Hepatolithiasis(HL)poses a significant risk for cholangiocarcinoma(CCA)development,with reported incidences ranging from 5%-13%.Risk factors include older age,smoking,hepatitis B infection,and prolonged HL duration.Chronic inflammation and mechanical stress on the biliary epithelium contribute to CCA pathogenesis.Hepatectomy reduces CCA risk by removing stones and atrophic liver segments.However,residual stones and incomplete removal increase CCA risk.Kim et al identified carbohydrate antigen 19-9,carcinoembryonic antigen,and stone laterality as CCA risk factors,reaffirming the importance of complete stone removal.Nonetheless,challenges remain in preventing CCA recurrence post-surgery.Longer-term studies are needed to elucidate CCA risk factors further.

Arterial Duct Stenting Versus Modified Blalock-Taussig Shunt in Patient with Ductal-Dependent Pulmonary Circulation: Systematic Review & Meta-Analysis

Objective:Patients with ductal-dependent pulmonary circulation require alternative bloodflow to provide and maintain adequate oxygenation.Modified Blalock-Taussig Shunt(MBTS)has been the standard for providing such a result.Currently,less invasive methods such as Arterial Duct(AD)stenting have been performed as alter-natives.This study aims to compare the outcome of AD stenting and MBTS.Method:Systematic research was performed in online databases using the PRISMA protocol.The outcomes measured were 30-day mortality,com-plication,unplanned intervention,oxygen saturation,duration of hospital,and ICU length of stay.Any compara-tive study provided with full text is included.The outcome of each study was analyzed using a trandom effects model with relative risk and mean difference as the effect size.Bias risk assessment was conducted using the New-castle-Ottawa Scale.All analyses were performed using Review Manager 5.4.1.Result:A total of 11 studies with 3154 samples included in this study.There is no significant difference in 30-day mortality between the two groups(p-value=0.10).However,there is significantly less complication(RR 0.53[0.35,0.82];p-value=0.004)and unplanned intervention(RR 0.59[0.38,0.92];p-value=0.02)in the AD stent group.Comparison of the Nakata index showed no significant difference(p-value=0.88).Post-operative oxygen saturation was measured signifi-cantly higher in the AD stenting(MD 1.80[0.85,2.74];p-value=0.0002).However,AD stent group shows sig-nificantly lower long-term oxygen saturation(MD-8.43[-14.38,-2.48];p-value=0.005).Both hospital and ICU length of stay was significantly shorter in the AD stent group(MD-8.30[-11.13,-5.48];p-value<0.00001;MD-5.09[-7.79,-2.38];p-value=0.0002).Conclusion:AD stenting provides comparable outcomes relative to MBTS as it provides less complication and unplanned intervention and higher post-procedural O2 saturation.However,MBTS proved its superiority in maintaining higher long-term oxygen saturation and still became the preferred option to manage complex cases where stenting is either challenging or unsuccessful.

Benefits of endoscopic gallbladder stenting following percutaneous transhepatic gallbladder drainage

BACKGROUND Endoscopic transpapillary gallbladder drainage is challenging because of the complexity of the procedure and high incidence of adverse events(AEs).To overcome these problems,endoscopic gallbladder stenting(EGBS)after percutaneous transhepatic gallbladder drainage(PTGBD)can be effective,as it mitigates inflammation and adhesion.AIM To examine the benefits of EGBS after PTGBD to assess its efficacy and impact on AEs.METHODS We retrospectively analyzed data from 35 patients who underwent EGBS after PTGBD at a single center between January 2016 and December 2023.The primary outcomes were technical success and AEs,and the rate of recurrent cholecystitis was evaluated.In addition,the reasons for the failure of the procedure were identified.RESULTS Among the 35 patients,the technical success rate was 77.1%and the final contrast of the cystic duct was successful in 97.1%of patients.The incidence of early AEs was relatively low(11.4%),with no instances of cystic duct perforation.The rate of recurrent cholecystitis was 3.7%,and no other biliary events were observed.CONCLUSION EGBS after PTGBD may be significantly beneficial,with a substantial success rate and minimal AEs in both short-and long-term follow-ups.

Conversion surgery after gemcitabine and cisplatin plus durvalumab for advanced intrahepatic cholangiocarcinoma:A case report

BACKGROUND The combination of immune checkpoint inhibitors and chemotherapy has shown promising results for the treatment of advanced biliary tract cancer(BTC).Based on the results of the TOPAZ-1 trial,a gemcitabine and cisplatin plus durvalumab(GCD)regimen was recently approved as first-line therapy for patients with advanced BTC.However,post-GCD conversion surgery has not been previously studied.Herein,we describe a case of advanced intrahepatic cholangiocarcinoma(ICC)successfully treated with radical surgery after GCD.CASE SUMMARY A 65-year-old female diagnosed with advanced ICC with periductal infiltration into the hepatic hilum underwent eight cycles of GCD,followed by durvalumab maintenance treatment,with mild adverse events.Partial response was obtained.Subsequently,a conversion surgery with extended left hepatectomy and bile duct resection was performed.The resection margins were negative,and the pathological diagnosis was compatible with small duct type ICC.The patient remained disease-free for 8 months without adjuvant chemotherapy.CONCLUSION We describe the case of a patient who received successful conversion surgery after GCD treatment for advanced ICC.

Imaging features of malignant vs stone-induced biliary obstruction:Aspects to consider

Radiological studies play a crucial role in the evaluation of patients with biliary duct obstruction,allowing for the guidance of clinical diagnosis towards a malignant or stone-induced etiology through the recognition of relevant imaging features,which must be continuously revisited given their prognostic significance.This article aims to emphasize the importance of recognizing crucial imaging aspects of malignant and stone-induced biliary obstruction.

Surgically treating a rare and asymptomatic intraductal papillary neoplasm of the bile duct:A case report

BACKGROUND Intraductal papillary neoplasms of the bile duct(IPNBs)are rare and characterized by papillary growth within the bile duct lumen.IPNB is similar to obstructive biliary pathology.In this report,we present an unexpected case of asymptomatic IPNB and consolidate our findings with the relevant literature to augment our understanding of this condition.Integrating relevant literature contributes to a more comprehensive understanding of the disease.CASE SUMMARY A 66-year-old Chinese male patient was admitted to our hospital for surgical intervention after gallstones were discovered during a routine physical examination.Preoperative imaging revealed a lesion on the left side of the liver,which raised the suspicion of IPNB.A laparoscopic left hemihepatectomy was performed,and subsequent histopathological examination confirmed the diagnosis of IPNB.At the 3-mo postoperative follow-up,the patient reported good recovery and no metastasis.IPNB can manifest both latently and asymptomatically.Radical surgical resection is the most effective treatment for IPNB.CONCLUSION Hepatic and biliary masses,should be considered to diagnose IPNB.Prompt surgery and vigilant follow-up are crucial in determining prognosis.

Laparoscopy combined with hysteroscopy in the treatment of Robert’s uterus accompanied by adenomyosis:A case report

BACKGROUND Gynaecologists should be aware of a rare obstructive Mullerian duct abnormality like Robert’s uterus and perform further surgery when necessary.CASE SUMMARY We report a 41-year-old mother of two children with Robert’s uterus who was examined and treated by laparoscopy and hysteroscopy.Unlike the existing cases reported in the literature,this patient had a late onset of Robert’s uterus symptoms.Due to right tubal ectopic pregnancy 3 years previously,the patient was treated with right salpingectomy and left tubal ligation but suffered aggravated left lower abdominal pain.She was examined and treated by laparoscopy and hysteroscopy,and is completely asymptomatic at 5-year followup.CONCLUSION The typical obstructive Mullerian abnormality requires further surgery.Combined laparoscopy and hysteroscopy is an effective,minimally invasive technique with better recovery outcomes than traditional transabdominal procedures.

Pitfalls in internal jugular vein cannulation

Central venous catheter insertion in the internal jugular vein(IJV)is frequently performed in acute care settings,facilitated by its easy availability and increased use of ultrasound in healthcare settings.Despite the increased safety profile and insertion convenience,it has complications.Herein,we aim to inform readers about the existing literature on the plethora of complications with potentially disastrous consequences for patients undergoing IJV cannulation.