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In rivers, the addition of finer sediment to a coarser riverbed is known to increase the mobility of the coarser fraction. Two mechanisms have been suggested for this: a geometric mechanism whereby smaller sizes smooth the bed, increasing near-bed velocity and thus mobility of the larger sizes, and a viscous mechanism whereby a transitionally smooth turbulent boundary layer forms, rendering the coarser grains more mobile. Here, we report on experiments using two sediment mixtures to better understand these proposed mechanisms. In Mixture 1, we used 0.5 and 5 mm grains, and in Mixture 2, we used 2 and 20 mm grains. If the entrainment of coarse gravel by finer sediment is a purely geometric effect, then the addition of finer material should produce the same effect on the mobility of the coarser material for both mixtures because they have the same size ratio. We show that addition of finer material has a different effect on the two mixtures. We observed an increase in the mobility of the coarse fraction for both mixtures, but the increase in coarse fraction mobility for Mixture 1 was almost twice that for Mixture 2. Our experiments show that in addition to the geometric effect, enhancement of coarse gravel transport by finer sediment is also driven by a viscous effect., Competing Interests: Competing interests statement:The authors declare no competing interest.

Key Clinical Message: Contraceptive implant migration is a rare complication associated with contraceptive implants: migration to the ulnar nerve, emphasizing the importance of accurate diagnosis, imaging, and a multidisciplinary approach to mitigate neurovascular risks during insertion and removal procedures. The case report demonstrates the necessity for careful removal techniques and thorough patient follow-up to ensure positive outcomes and prevent long-term nerve damage., There are some potential risks and complications associated with contraceptive implants, including neurovascular injury. The aim of this case report is to report a rare complication associated with contraceptive implants. A 32-year-old female, right-hand dominant, presented to the orthopedic clinic for the extraction of a contraceptive implant (Implanon) from her left arm. She reported intermittent numbness in the ring and little fingers. Upon examination, the Implanon was not palpable. Both Phalen's test and Tinel signs were negative. An x-ray of the arm revealed the implant's position. Under local anesthesia through a longitudinal incision, the Implanon was found within the perineurium of the ulnar nerve. Two weeks after the operation, the patient returned to the clinic. Upon examination, there were no indications of ulnar nerve neuropathy. If a patient undergoes subdermal implant-associated pain or is at risk of neurovascular damage during removal, it is advisable to refer the patient to a family planning specialist experienced in handling challenging implant removals, and subsequently to a peripheral nerve surgeon, to optimize outcomes. The migration of a contraceptive implant to the ulnar nerve is an exceedingly rare but possible complication., Competing Interests: The authors declare no conflict of interest., (© 2024 The Author(s). Clinical Case Reports published by John Wiley & Sons Ltd.)

Mediastinal parathyroid cysts (MPCs) are extremely rare, benign lesions arising from the parathyroid glands and residing within the thoracic cavity. This study aims to advance understanding of MPC, emphasizing accurate diagnosis and management approaches for this rare condition. A 46-year-old woman presented with dysphagia for one week. Blood tests revealed elevated parathyroid hormone (PTH) (112.8 pg/mL) and normal serum calcium (9.54 mg/dL). Ultrasonography identified a large, well-defined cystic nodule measuring 46 × 30 × 25 mm, extending retro-sternally in the right upper third of the chest. A subsequent high-resolution computed tomography scan of the chest revealed a large space-occupying lesion (47 × 43 × 31 mm) in the superior mediastinum, near the esophagus, suggesting an esophageal duplication cyst or, less likely, a bronchogenic cyst. Video-assisted thoracoscopic surgery (VATS) was performed, and the entire cyst was excised, confirmed histologically as a mediastinal parathyroid cyst. Mediastinal involvement of PCs poses diagnostic challenges due to their rarity and diverse clinical presentations. Surgical excision is necessary for symptomatic cases, with VATS emerging as a favorable approach., (© 2024 The Authors. Published by Elsevier Inc. on behalf of University of Washington.)

There are controversies regarding the management of umbilical pilonidal sinuses. The current study aims to report on the efficacy of a non-operative, umbilical conserving procedure in the treatment of umbilical pilonidal sinus. This is a prospective, single cohort study. The cases were managed in a single private practice center. Patients were assessed and managed throughout the previous nine years (from January 2013 to June 2022). The required information was obtained from the center's medical database. The current study included 114 patients. There were 82 (71.9%) male patients. The patients' ages varied from 14 to 56 years (mean = 23.24). The umbilicus was retracted under local anesthesia. The sinuses were cleaned with povidone-iodine. Following the drying of the cavity, the mixture was put in the umbilicus, and the area was dressed. The amount of mixture was determined by the size of the cavity. Following treatment, the patients were directly discharged home with instructions to remove all hair from the chest and abdomen and keep the dressing dry for three days. After three days, the patients were advised to use a clean cotton swab to remove the injected mixture. Recurrence was reported in 5 cases (4.4%). The current technique might be used effectively in the treatment of umbilical pilonidal sinus. It is an umbilical preserving technique with a minimal recurrence rate., (© 2023 The Authors. International Wound Journal published by Medicalhelplines.com Inc and John Wiley & Sons Ltd.)

Introduction: It is crucial to be aware of post-COVID-19 non-pulmonary complications. Avascular necrosis (AVN) is one of these complications. It should be noted that the risk of AVN persists in individuals who have recovered from the COVID-19 infection. The current study aims to report several cases of AVN after being infected with SARS-CoV-2., Materials and Methods: This is a single-centre retrospective case series conducted over a 2-year period (January 2021-December 2022) involving individuals who developed AVN after being infected with COVID-19., Result: The study included a total of 17 patients. The mean age of patients was 38.65±6.1 years. Twelve of them were male (70.6%) and five were female (29.4%), with a ratio of 3:1. The mean BMI of the patients was 28.3±2.4 kg/m 2 . Eleven (64.7%) patients reported administering steroid injections throughout the infection course. The mean interval between COVID-19 infection and presentation to the clinic was 6.53 months. The majority of patients (82.3%) complained of bilateral hip pain. Limping was observed in 47% of the cases. MRI showed AVN in all cases. Bilateral core decompression was performed in five cases (29.4%), total hip replacement in three cases (17.6%), and conservative treatment in nine cases (53%)., Conclusion: The ongoing pandemic may have many long-term sequelae. There is a risk of developing AVN after COVID-19., Competing Interests: The authors declare that they have no conflicts of interest.Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)

Although some recent studies have found that original and generic clopidogrel brands are acceptable and have the same pharmacokinetic and pharmacodynamic properties, there is insufficient evidence to compare the clinical effectiveness and safety of brand and generic clopidogrel. The current study aims to evaluate the clinical safety of brand and generic clopidogrel by comparing clinical outcomes in patients undergoing carotid endarterectomy (CEA)., Method: This was a single centre, parallel-arm, phase III, open-label, and randomized group sequential trial. It was conducted to compare the clinical safety of a brand and three generic clopidogrel forms in patients who have undergone CEA. All enrolled subjects were treated perioperatively with dual antiplatelet (aspirin and clopidogrel). The involved participants were assigned randomly into four groups based on the type of clopidogrel. Safety parameters were measured, including haematoma, blood draining from drainage, mouth deviation, tongue deviation, and stroke. SPSS software was used to perform the data analysis., Results: The trial included 80 patients in total (20 patients per group). Thirty-one (38.8%) patients were male. The mean age of patients was 65.6 years (49-79). Eighteen (22.5%) patients had a history of previous coronary intervention, and seventeen (21.3%) had symptomatic carotid artery stenosis. Overall, Plavix or Piax combined with aspirin were linked to better clinical safety than the other two generic clopidogrel, as the amount of bleeding was nearly two times lower in patients treated with Plavix or Piax (270±92.39 and 271.5±80.60, respectively) compared to PlavigrelAwa or Plavineer (505.7±169.1 and 496.5±174.6, respectively) ( P ≤0.001)., Conclusion: The findings of the current study showed diversity in clinical safety of different clopidogrel formulations that were provided perioperatively in CEA patients., Competing Interests: The authors declare that they have no competing interests., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)

Introduction: Covid-19 vaccines have been assessed in randomized trials, which are designed to establish efficacy and safety, but are insufficient in power to detect rare adverse outcomes. Among the adverse cardiac events associated with mRNA COVID-19 vaccines are inflammations (e.g., pericarditis or myocarditis), thrombosis, and ischemia., Objective: This systematic review aims to evaluate the reported cases of myocardial infarction (MI) after COVID-19 vaccinations., Method: Web of Science, MEDLINE on OVID, PubMed, and Google Scholar were searched for English-language papers published until March 25, 2022., Results: This study included 15 papers (10 case reports and 5 case series). In total, 20 individuals were included who had received COVID-19 vaccines and experienced MI. Males (55%) reported more adverse occurrences than females (45%) across the majority of event categories. The mean time from the administration of the vaccine to the onset of symptoms was 2 days (0-10 days). The AstraZeneca vaccine was responsible for more than half of the reported events. In the majority of cases, the event developed after receiving the first dose of vaccination., Conclusion: MI related to COVID19 vaccination is a rare, but serious and life-threatening condition. Chest discomfort should be regarded as a warning sign, particularly in people who have been administered a dose of the vaccine within the previous two days., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s).)

During its 6,300-km course from the Tibetan Plateau to the ocean, the Yangtze River is joined by two large lakes: Dongting Lake and Poyang Lake. We explain why these lakes exist. Deglaciation forced the ocean adjacent to the Yangtze mouth to rise ∼120 m. This forced a wave of rising water surface elevation and concomitant bed aggradation upstream. While aggradation attenuated upstream, the low bed slope of the Middle-Lower Yangtze River (∼2 × 10 -5 near Wuhan) made it susceptible to sea level rise. The main stem, sourced at 5,054 m above sea level, had a substantial sediment load to "fight" against water surface level rise by means of bed aggradation. The tributaries of the Middle-Lower Yangtze have reliefs of approximately hundreds of meters, and did not have enough sediment supply to fill the tributary accommodation space created by main-stem aggradation. We show that the resulting tributary blockage likely gave rise to the lakes. We justify this using field data and numerical modeling, and derive a dimensionless number capturing the critical rate of water surface rise for blockage versus nonblockage.

Chylothorax is the accumulation of chyle in the pleural cavity that typically contains a high concentration of triglycerides. Blunt chest trauma is a rare cause. The aim of this study is to review all of the reported cases of chylothorax caused by blunt chest trauma. Available databases were explored systematically for the condition and the eligible papers were included. The literature search revealed 30 studies with 39 cases, 72.3% of the cases were male, and 21.7% of the patients were female. The age range varied between 4 and 75 years with a mean age of 35.8 years. All of the patients were diagnosed after fluid sampling from the pleural fluid by thoracentesis and/or chest tube insertion. About 71.4% of the patients were treated successfully by conservative management: others (28.6%) were managed surgically. Although it is a rare condition, persistent milky drainage after blunt chest trauma should raise the suspicion of chylothorax. Pleural fluid sampling is the cornerstone of the diagnosis. In the majority of the cases, conservative treatment is quite enough. Surgery is indicated whenever non-operative measures failed., Competing Interests: Conflict of interestThe authors declare that they have no conflict of interest., (© Indian Association of Cardiovascular-Thoracic Surgeons 2020.)

Introduction: Enterobius vermicularis is one of the commonest parasitic infestations worldwide but its association with acute appendicitis remains controversial. It is very rarely encountered during appendectomy. The aim of this paper is to report a case of acute appendicitis caused by Enterobius vermicularis. A 23-year-old housewife presented with a right lower abdominal pain for the past 8 h. Clinical examination revealed right iliac fossa tenderness upon palpation and rebound tenderness upon release. The patient was diagnosed as a case of suspected acute appendicitis. The patient was anesthetized and intubated. Delivery of the vermiform appendix done through right grid iron incision. Intra operatively an inflamed appendix obstructed by Enterobius vermicularis was noted., Conclusion: Enterobius vermicularis can habit the appendix and induce the signs and symptoms of A.A with or without actual histopathological acute appendicitis. The treatment of choice is surgical resection of the appendix., (Copyright © 2019 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Introduction: lipoma is the most frequent soft tissue tumor in adults. Its occurrence in the retroperitoneal region is extremely rare. The aim of this study is to report a case of retroperitoneal lipoma with a literature review., Presentation of Case: A 34-year-old female presented with abdominal distension and severe back pain for one year duration. She also reported weight loss and constipation. The examination revealed asymmetrical abdominal distension and everted umbilicus. There was a big irregular mass occupying the whole abdomen reaching into the xiphisternum, firm in consistency, smooth surface, and well defined borders. Abdominal ultrasound demonstrated a large retroperitoneal heterogeneous mass. Computed tomography (CT) scan showed a large well defined hyperechoic mass with fibrous septa extending from the left ovary up to the diaphragm. Exploratory laparotomy revealed a giant clearly demarcated fatty tumor adherent to the retroperitoneal fatty tissues. The histopathological examination of the specimen confirmed the diagnosis of the retroperitoneal lipoma., Discussion: Retroperitoneal lipomas have been reported in various age groups; namely children, middle and old age patients. Based on the characteristic radiological features of the tumor, enormous diagnostic work-up is not justified., Conclusion: Retroperitoneal lipoma is a very rare variant of lipoma, presents with various signs and symptoms that may be misleading. Radiologic imaging especially CT scan is the diagnostic tool of choice. Surgical resection is the main modality of management., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)