Search

The electric spring (ES) is a reactive compensator which is series with a noncritical load. This paper utilizes the ES in the distribution networks and examines the underlying performance operationally and economically. A virtual generator model for the electric spring is proposed to ease the study of power systems. An algorithm based on the backward/forward sweep method is proposed for solving the optimal power flow. Then, with a 24‐hour real price and load data of ISO‐NE market, the performance of ES is evaluated operationally and economically in two distribution systems. The ESs may exchange reactive power between each other and this raises active and reactive power losses. To cope this problem, the feeders' voltages of the middle load demand are set as the reference voltages of ESs in each feeder so, each ES has a different reference voltage to cease the ES power exchanges. In this work, indexes such as voltage profile, active power loss, reactive power loss, power factor, electric bill payment, net present value, internal rate of return and the payback year are measured. The results of case study confirm the ES improves power loss, voltage profile, power factor, and stability while it reduces the operation cost. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to evaluate the effect of coronavirus disease (COVID-19) on the patients' referral in the pregnant population and also investigate each treatment approach's advantages and disadvantages for acute renal colic in pregnancy. Methods: In this retrospective study, we included all pregnant women with ureteral stones referred to a referral center between January 2019 and March 2021. Results: Among 53 pregnant women, 18 (33.9%) were on conservative therapy, which passed the stone without any complications. Double J stent or nephrostomy tube insertion was done for 24 patients (45.2%). Seventeen of these patients (70.8%) presented post-surgical complications, including hematuria (29.2%), pyelonephritis (20.8%), and lower urinary tract symptoms (20.8%). Transurethral lithotripsy (TUL) was done in 11 patients (20.7%). Only one of these patients developed hematuria following TUL. Thus, in our population study, double J stent or nephrostomy insertion was associated with a higher chance of postoperative complications than TUL (p -value = 0.001). Thirty-six patients were referred within 13 months before the entry of COVID-19, while 17 were referred during a similar approximate duration after the COVID-19 entry into the country. Only the initial presentation had a significant difference between these two periods (p -value = 0.034). Conclusions: When conservative treatment fails, we recommend TUL as the second-line treatment over temporary procedures, such as double J stent or nephrostomy insertion. Of note, in a group of patients with an emergent clinical setting, including active infection, deteriorating renal function, signs of preterm labor, solitary kidney, etc., double J or nephrostomy tube insertion remains the preferred management method for its fast resolution of obstruction and infection. Besides, a decrease in visits with an increase in complicated cases after COVID-19 was observed, maybe due to a delay in referring. [ABSTRACT FROM AUTHOR]

• A control strategy founded on active and reactive power compensations has been proposed for critical loads. • The proposed controller has two voltage control loops which adjusts active and reactive power of the electric spring. • The experimental results show that the proposed control strategy can effectively mitigate double voltage control. • Both critical and non-critical loads are considered. The electric spring (ES) is a novel voltage compensator which is series with a non-critical load to regulate the critical load voltage. The voltage fluctuation is caused by wind speed fluctuation, load fluctuation, and generator tripping. In busbar voltage drop situation, the electric spring decreases the voltage of non-critical load in order to support the critical load (busbar) voltage. All the non-critical loads couldn't work under any voltage (for example 0.5 pu). In this paper, a control strategy founded on active and reactive power compensations has been proposed for voltage control of critical loads on a reference value while it controls the voltage of non-critical loads between an acceptable boundary. The proposed controller has two voltage control loops which adjusts active and reactive power of the electric spring. The experimental results from the case study show that the ES with the proposed control strategy can effectively mitigate double voltage control of both critical and non-critical loads while dynamically managing the demand response of the system at the same time. [ABSTRACT FROM AUTHOR]

Objective: The objective of the study was to assess the outcome and feasibility of ultrasonography (US)-guided minimally invasive percutaneous nephrolithotomy (mini-PCNL) in children.Materials and Methods: Twenty-five children with upper urinary tract stones who had undergone US-guided mini-PCNL from June 2017 to June 2020 were enrolled in this study. Patients' demographic information and post-treatment results were retrospectively gathered and analysed. Pyelocaliceal system was punctured in prone position using US guidance, and the tract was dilated using single-shot dilation technique. All steps of renal access were done using only US. Mini-PCNL in all cases was done by using 15 Fr rigid nephroscope. Stones were fragmented with a pneumatic lithotripter and evacuated.Results: The patients' mean age was 6.30 ± 3.25 years (range: 1.5-15). The mean stone size was 16.04 ± 3.93 mm (range: 10-30). The mean access time to the stone was 1.50 ± 0.62 min (range: 1-4). The mean operation time was 94.66 ± 3.05 min (range: 90-100 min). The final stone-free rate was 96%. Post-operation fever occurred in 4 (16%) patients who were treated successfully with an antibiotic. No major complications occurred.Conclusions: We recommend US-guided mini-PCNL as a harmless alternative treatment option, in children with renal calculi due to its excellent outcomes and little complications. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to determine which voltage regulation strategies best allow grid-tied Photovoltaic (PV) Systems to be integrated into distribution networks. More particularly, this involves performing a literature review on the negative impacts of grid-tied PV systems on distribution networks, and also the current and proposed voltage regulation methods available. The next step is to assess, through simulation, which strategies allow the greatest amount of PV to be integrated with minimal effect on power quality. This will be done by simulating various Medium Voltage (MV) and Low Voltage (LV) radial feeders under varying load conditions and changing solar irradiance levels. Real network data will be incorporated with an accurate model for PV output power to accurately model high penetrations of PV. Our research highlights the necessity of reducing peak loadings through strategies such as energy storage, off-peak loading methods, and reactive power control of inverters to decrease the voltage deviations. It has been shown that voltage rise and reverse power-flows can and should be avoided on distribution feeders. Voltage unbalances can also be easily avoided by following the simple steps outlined in this paper. Now, a proactive approach should be taken by Governments, Distribution Networks System Providers, and customers with PV to ensure that as penetrations increase, Power Quality is not diminished. [ABSTRACT FROM AUTHOR]

Purpose: In this study, we aimed to build a 3D reconstruction computed simulation model and to establish a regression equation for detecting the testis's temperature by its location after first staged open orchidopexy in children with abdominal undescended testis (UDT) and short spermatic cords. Methods: In this cross-sectional study, we enrolled 31 children with abdominal UDT and short spermatic cords who underwent first staged orchiopexy between 2017 and 2020. Using ultrasonography to obtain the testis's location distance from the skin surface (X1), external iliac vessel (X2), and internal inguinal ring (X3), we input the data into a 3D reconstruction computed simulation along with COMSOL to calculate the testicular temperature. We also used multivariate regression to establish the testicular temperature regression equation from the gathered data. Result: The mean age of the participants was 4.47 ± 1.21 years. The mean size of the operated testis was 0.39 ± 0.13 cc. The mean distance of the testis from X1, X2, and X3 was 3.27 ± 1.25 mm, 21.06 ± 6.42 mm, and 27.19 ± 10.09 mm, respectively. The testicular temperature regression equation derived from testis location was calculated by the formula: 34.57 + 0.0236 X1 ² - 0.0105 X2 - 0.0018 X3. The concordance for testis temperature calculated via the computational method and regression equation was 83%. Conclusions: The current study provided a reference value for the testicular temperature of children with abdominal UDT and short spermatic cords after the first stage of orchiopexy. A testicular temperature regression equation can be established based on the testis location, which will provide relevant information for the testicular development assessment, disease diagnosis, and follow-up, and possibly determination of the time of the second stage of orchiopexy. [ABSTRACT FROM AUTHOR]

Ureteral calculi management in patients with urinary diversion is challenging for most urologists. The surgeon should consider the patient's diversion type, BMI, stone size and location, and his/her experience with the procedure. We report an 85‐year‐old ileal conduit diversion man presented with ureteral calculi and treated via antegrade ureteroscopic lithotripsy. [ABSTRACT FROM AUTHOR]

Hydatid cyst (HC) disease is a parasitic infection produced by cysts containing the Echinococcus granulosus larval phase. Patients with HC disease are typically asymptomatic until incidentally diagnosed or when complications occur. A rare presentation of liver HC is spontaneous cutaneous fistualisation. We report a 63-year-old female patient admitted in a tertiary care hospital in Ibb, Yemen, in 2019 with an infected cutaneous fistula induced by a ruptured HC. The patient underwent laparotomy and partial cystectomy with excision of the fistula tract. Upon 6-month follow-up, there was no HC recurrence. This report highlights the need for physicians to consider this diagnosis when faced with an unusual cutaneous fistula near organs commonly involved in HC, especially in areas where the prevalence of this disease is high. [ABSTRACT FROM AUTHOR]

In this paper, a new modulation strategy based on the carrier-based switching strategy for the non-square direct matrix converters (MC) is proposed to control the active power of distributed generation (DG) units. In this strategy, the active power of DGs is controlled by the central input current control of the non-square direct MC independent from the voltage and frequency. Conventionally, each DG has a converter, and for supplying a load with N number of DGs, N number of converters are needed and each converter has its own modulation switching and control strategy to control the power output of each DG. Needless to say, in a microgrid with N number of DGs, the control strategy of each converter has more complex structure than that of a microgrid with one converter, and surely the former strategy entails more volume and price. Using the proposed converter in this paper, it is possible to supply a load with N number of DGs through one converter. Also, the power outputs of all DGs are controlled by a central control strategy. The proposed central control strategy is described and simulated for a typical microgrid. Experimental and simulation results validate the effectiveness of the proposed converter and the proposed strategy. The results demonstrate the applicability and efficiency of the system and verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate sympathetic skin response (SSR) among patients with Raynaud phenomenon (RP). SSR is a technique for assessment of the damage of peripheral neuropathies and the disorders of the sympathetic system. Methods: Between January 2015 and December 2018, approximately 20 patients with RP and 20 healthy subjects (control group) were recruited from patients referred to the outpatient clinics of Shiraz University of Medical Sciences, Shiraz, Iran. All participants were clinically examined and the SSR was evaluated using a standard protocol. SSR is abnormal when the latency is prolonged and/or the amplitude is reduced. Results: The RP group consisted of 19 women (95%) and one male (5%); three patients (15%) had primary Raynaud's phenomenon (PRP) and 17 patients (85%) had secondary Raynaud's phenomenon. The control group consisted of 16 women (80%) and four males (20%). The mean age of the RP group and control subjects was 43.1 ± 9 and 36.7 ± 8.6 years, respectively. The SSR to the electrical stimulus was absent in three patients with PRP. The total median nerve mean latencies in the upper limb were 1.90 ± 0.57 and 1.19 ± 0.52 seconds for the RP group and control groups, respectively (P <0.001). These findings revealed significantly prolonged SSR latencies in the RP group, while the mean amplitude showed no significant differences in both groups (P = 0.756). Conclusion: Absence or prolonged latency of SSR was associated with the disorders of the unmyelinated axons in the sympathetic system. The findings of the present study suggested the disorders of unmyelinated axons in Raynaud's phenomenon. [ABSTRACT FROM AUTHOR]

Renal oncocytoma is a benign tumor that arises from epithelial cells of the distal renal tubules. It is naturally presented with a small-sized mass, and giant oncocytoma is uncommon. Renal oncocytoma is frequently asymptomatic and challenging to distinguish preoperatively from renal cell carcinoma (RCC). We present a 40-yearold man who presented with intermittent abdominal pain in the last two years. Abdominal computed tomography (CT) scan showed a large, heterogenous left renal mass measured 15 x 16 x 19.5 cm and associated with central calcifications suspected of RCC. The patient underwent a left radical nephrectomy without complication. The histopathological study revealed typical oncocytoma features. There was no detected recurrence or distant metastasis on six months follow-up. In conclusion, it is challenging to distinguish renal oncocytoma from RCC via preoperative radiology images, especially when a giant mass is present. The only histopathology examination of the removed specimen can provide a definitive diagnosis. [ABSTRACT FROM AUTHOR]

Ritual circumcision is associated with a high rate of complications, mainly if performed by an untrained practitioner. Furthermore, excessive skin removal is a rare complication of this procedure that results in penis "trapping" underneath the skin and future sexual dysfunction. Here, we presented a 45-dayold Yemeni newborn with a trapped penis due to total loss of penile skin during a ritual circumcision performed by a traditional untrained practitioner using the guillotine technique one month ago. The patient underwent surgical exploration, and the penis was deliberated, released, and the skin defect was repaired with a single-step scrotal flap advancement over the penile shaft. At the sixmonth follow-up, the outcome was both functional and cosmetically satisfying. In conclusion, we recommend that the circumcision procedure be performed at the very least by an educated and skilled health professional. Additionally, a scrotal advancement flap is still an option in significant penile skin loss cases. [ABSTRACT FROM AUTHOR]

Cystic hygroma (CH) is a congenital malformation of the lymphatic system commonly treated with surgical excision. The typical locations of this lesion are the cervico-facial and cervicothoracic region and other rare locations include axilla, mediastinum, and limbs. CH usually presents at birth as a painless mass, which concerns parents. It might also be detected as complications resulting from it, such as respiratory distress fever, a sudden increase in the size, feeding difficulty, and infection. To the best of our knowledge, there are a few cases reported in cervico-axillo- thoracic variants and we reported giant cervico-axillo-thoracic cystic hygroma, which is thoroughly treated with surgical excision. A 45-days female, full-term delivery, infant presented with big right-side trunk mass, diagnosed through computed tomography scan as a CH involving the right lateral and posterior chest wall with extension to the axilla and right side of the neck, which was managed with surgical excision. After a 6-month of follow-up, no recurrent lesion masses were detected. CH is a congenital malformation of the lymphatic system that can be treated in the pediatric population. The treatment option depends on size, age, and location of the lesion. In our case, complete surgical excision was the selective treatment for this lesion. [ABSTRACT FROM AUTHOR]

Sarcomatoid urothelial carcinoma (UC) of the renal pelvis is rare. It is a high-grade malignant tumor that contains both epithelial and mesenchymal elements. Brain metastases from renal pelvis UC are infrequent and represented in few cases. We report a 68-year-old female with a right renal mass diagnosed as a UC with a sarcomatoid variant. The patient underwent a right radical nephroureterectomy and received chemotherapy. She developed brain metastasis in the left temporal area two months later. Therefore, metastasectomy and palliative brain radiotherapy were performed for her. Sadly, her general condition worsened, and she passed away after one month. Brain metastasis in patients with UC is rare and poorly understood. Therefore, we describe the clinico pathological characteristics, including the clinical follow-up of our case with a focus on the treatment and outcome. [ABSTRACT FROM AUTHOR]

Background: Miniaturization of endoscopic instruments in percutaneous nephrolithotomy (PCNL) allowed less invasive procedures with low complication rates, especially in children. This study was conducted to evaluate the safety and efficacy of ultrasonography-guided (USG) versus fluoroscopy-guided (FG) mini-PCNL in children. Materials and methods: This is a retrospective comparative study conducted from June 2015 to June 2020. The sample included 70 children (35 pateints underwent USG mini-PCNL and 35 pateints underwent FG mini-PCNL). They were compared mainly by the patients’ demographic characteristics, procedural information, and post-treatment outcomes. In the USG mini-PCNL group, puncturing was performed using a 3.5 MHz US probe, whereas fluoroscopy was utilized in the FG mini- PCNL group. Results: Both groups were comparable in terms of gender, previous history of failed ESWL, and hydronephrosis grade. The mean stone burden was 15.94 ± 3.69 mm and 19.20 ± 7.41 mm in USG and FG groups, respectively (p = 0.024). The stonefree rate (SFR) was 97.1% in the USG group and 94.3% in the FG group, which was not statistically significant (p = 0.16). Mean operative time in the USG group and FG group was 69.00 ± 13.33 minutes and 63.48 ± 16.90 minutes, respectively. Four (11.4%) patients in the FG group required blood transfusions to restore the hemodynamic state (p = 0.039). Fever was detected in 4 (11.4%) patients in the USG group and 15 (31.4%) patients in the FG group (p = 0.041). Conclusions: In children, mini PCNL under USG is safe and as effective as fluoroscopy. [ABSTRACT FROM AUTHOR]