136 research outputs found

    Esophageal atresia associating gastrointestinal malformations: a study of clinical approach

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    Digestive tract malformations requiring surgical repair in association with esophageal atresia are rare occurrences. Because of this uncommon presentation of esophageal atresia, its evaluation and management are often difficult, requiring extensive workup and multiple surgical procedures. We present our experience with esophageal atresia associating gastrointestinal congenital anomalies in the last 10 years. Clinical and surgical perspectives were pointed willing to make relevant observations in matters of diagnosis and treatment strategy in these patients. Therefore, 7 cases resembling this pattern were identified – duodenal atresia and anorectal malformation being the most common coexistent malformations. All the cases exhibited technical and procedural staging difficulties that we shaped according to the patient’s general picture in the absence of a standardized approach. Careful preoperative follow-up, multidisciplinary communication, watchful waiting and an individually patient-shaped approach are elementary requirements for good outcomes in complex cases of EA

    A para-differential renormalization technique for nonlinear dispersive equations

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    For \alpha \in (1,2) we prove that the initial-value problem \partial_t u+D^\alpha\partial_x u+\partial_x(u^2/2)=0 on \mathbb{R}_x\times\mathbb{R}_t; u(0)=\phi, is globally well-posed in the space of real-valued L^2-functions. We use a frequency dependent renormalization method to control the strong low-high frequency interactions.Comment: 42 pages, no figure

    Single Active Nanoelectromechanical Tuning Fork Front-End Radio-Frequency Receiver

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    Nanoelectromechanical systems (NEMS) offer the potential to revolutionize fundamental methods employed for signal processing in today's telecommunication systems,1-4 owing to their spectral purity and the prospect of integration with existing technology. In this work, we present a novel, front-end receiver topology based on a single-device silicon nanoelectromechanical mixer-filter. The operation is demonstrated by using the signal amplification in a field effect transistor (FET) merged into a tuning fork resonator. The combination of both a transistor and a mechanical element into a hybrid unit enables on-chip functionality and performance in silicon previously unachievable. Signal mixing, filtering and demodulation are experimentally demonstrated at very high frequencies (>100 MHz), maintaining a high quality factor of Q=800, and stable operation at near ambient pressure (0.1 atm) and room temperature (T=300 K). The results show that ultimately miniaturized, silicon NEMS can be utilized to realize multi-band, single-chip receiver systems based on NEMS mixer-filter arrays with reduced system complexity and power consumption

    Phase-locked loop based on nanoelectromechanical resonant-body field effect transistor

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    We demonstrate the room-temperature operation of a silicon nanoelectromechanical resonant-body field effect transistor (RB-FET) embedded into phase-locked loop (PLL). The very-high frequency resonator uses on-chip electrostatic actuation and transistor-based displacement detection. The heterodyne frequency down-conversion based on resistive FET mixing provides a loop feedback signal with high signal-to-noise ratio. We identify key parameters for PLL operation, and analyze the performance of the RB-FET at the system level. Used as resonant mass detector, the experimental frequency stability in the ppm-range translates into sub atto-gram (10(-18) g) sensitivity in high vacuum. The feedback and control system are generic and may be extended to other mechanical resonators with transistor properties, such as graphene membranes and carbon nanotubes. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4758991

    Sustained Nano-Mechanical Oscillation of a Resonant-Body Transistor by Frequency-Modulated Heterodyne Phase-Locked-Loop

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    Many applications based on resonant nanoelectromechanical systems (NEMS) require monitoring their natural frequency of oscillation over time with high precision, e.g. for gas sensing or nanomechanical mass spectrometry. In this study, we integrate a very-high frequency, nanomechanical resonant-body field-effect transistor into a frequency-modulated phase-locked loop (FM-PLL) which operates analog, requires only one frequency source, and simultaneously exploits the low-noise displacement detection based on FM-demodulation with resonant transistors. We demonstrate sustained mechanical oscillation of a 120 MHz doubly-clamped nano-resonator (54 nm thick, 158 nm wide, 2.65 μm long) by using the FM-PLL in vacuum and in air, reaching a frequency stability in the low ppm-range at room temperature

    Spontaneous resolution and the role of endoscopic surgery in the treatment of primary obstructive megaureter: a review of the literature

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    The megaureter accounts for almost a quarter of all urinary tract dilations diagnosed in utero and is the second leading cause of hydronephrosis in newborns, following pyeloureteral junction obstruction. The current standard treatment for progressive or persistent, symptomatic primary obstructive megaureter is ureteral anti-reflux reimplantation, which can be associated with ureteral remodeling or plication. Due to the associated morbidity, postoperative recovery challenges, and the complications that may arise from the open surgical approach, there has been a natural inclination towards validating new minimally invasive techniques. This study reviews the literature, extracting data from three major international databases, from 1998 to 2022. Out of 1172 initially identified articles, only 52 were deemed eligible, analyzing 1764 patients and 1981 renal units. Results show that 65% of cases required surgical intervention, with minimally invasive techniques constituting 56% of these procedures. High-pressure endoscopic balloon dilation was the preferred endourologic technique. The degree of ureterohydronephrosis is considered one of the factors indicating the need for surgery. There is an inverse relationship between the diameter of the ureter and the likelihood of spontaneous resolution. Conditions such as renal hypoplasia, renal dysplasia, or ectopic ureteral insertion strongly indicate a poor prognosis. Endoscopic surgical techniques for treating primary obstructive megaureter can be definitive, firstline treatment options. In selected cases, they might be at least as effective and safe as the open approach, but with advantages like quicker recovery, fewer complications, shorter hospital stays, and reduced costs

    A pedunculated esophageal chondromatous hamartoma in a child

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    Esophageal tumors are uncommon in pediatric population and most of them are benign. Esophageal hamartomas have been reported extremely rare in children. These can present as intramural tumors of the esophageal wall or as polyps. Dysphagia is the main symptom described in their case, but other specific symptoms are also reported. Such symptoms encountered in clinical practice are represented by obstructive apnea episodes and bradycardia, poor weight gain, epigastric or retrosternal pain, hematemesis or melena, dysphonia or tracheal sounds. Diagnosis can be delayed due to the insidious onset and non-specific symptoms, therefore patient’s compliance to follow-up and broad, careful evaluation are mandatory. Preoperative imagistic assessment is extremely important for a precise definition of the tumor’s anatomical relations, especially when facing large tumors located in the posterior mediastinum. Herein we report a case of a large chondromatous polypoid hamartoma of the esophagus in a 9 years old boy, emphasizing over the diagnosis and surgical challenges we have met, along with comments on illustrative similar cases reported in the literature

    Опухоли почек у детей - опухоль Вильмса

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    Renal tumours represent between 4.4 and 6.3% of all malignant tumours of the children, which requires a thorough knowledge of the types of tumours that can appear at this age group with the purpose of diagnosing and adequately treating these pathologies.Tumorile renale reprezintă între 4,4% și 6,3% din formațiunile tumorale maligne ale populației pediatrice1, ceea ce face necesară o cunoaștere a tipurilor de formațiuni tumorale ce pot apărea la aceasta categorie de vârsta în scopul unui diagnostic si tratament adecvat.Опухоли почек составляют от 4,4 % до 6,3 % злокачественных опухолй в педиатрической популяции, что делает необходимым знание типов опухолей, которые могут возникать в этой возрастной группе, для правильной диагностики и лечения
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