RESUMO
Recent transport measurements [Churchill et al. Nature Phys. 5, 321 (2009)] found a surprisingly large, 2-3 orders of magnitude larger than usual (13)C hyperfine coupling (HFC) in (13)C enriched single-wall carbon nanotubes. We formulate the theory of the nuclear relaxation time in the framework of the Tomonaga-Luttinger liquid theory to enable the determination of the HFC from recent data by Ihara et al. [Europhys. Lett. 90, 17,004 (2010)]. Though we find that 1/T(1) is orders of magnitude enhanced with respect to a Fermi-liquid behavior, the HFC has its usual, small value. Then, we reexamine the theoretical description used to extract the HFC from transport experiments and show that similar features could be obtained with HFC-independent system parameters.
Assuntos
Espectroscopia de Ressonância Magnética/métodos , Nanotubos de Carbono/química , Solventes/química , Modelos Químicos , Pontos Quânticos , TemperaturaRESUMO
PURPOSE: Nonparasitic splenic cysts (NPSCs) are uncommon in children. The aim of this multinational and multicentric study was to present the authors' experience as well as the changing trends in the management of NPSCs over the last 25 years. MATERIAL AND METHODS: From 1981 to 2005, 50 children or adolescents were surgically treated for NPSCs in 6 paediatric surgical centres in four European countries. The medical records of these 50 patients with NPSCs were reviewed retrospectively. RESULTS: Twenty-six male and 24 female patients were operated on. Age at surgery ranged from 1 to 17 years (mean 11.9). Seventeen patients were symptomatic. Six total (4 open and 2 laparoscopic) and 26 partial (22 open and 4 laparoscopic) splenectomies were performed. Laparoscopic fenestration or deroofing and open cystectomy was carried out in 9 patients, respectively. Histological findings revealed the lesion to be an epidermoid cyst (n = 28), a pseudocyst (n = 15) or a mesothelial cyst (n = 2). In 5 patients haemangioma or lymphangioma was the pathological diagnosis. At a mean follow-up of 2.9 years, residual cysts were found in 8 laparoscopically treated patients, 4 of whom required re-do laparoscopy or open surgery. CONCLUSIONS: Over the last two decades, the surgical treatment of NPSCs has changed from a formerly customary total splenectomy to spleen-conserving procedures, such as total cystectomy with or without partial splenectomy or partial cystectomy. These therapeutic modalities can be performed laparoscopically, if technically possible. Fenestration or deroofing of the cyst resulted in a high recurrence rate (7/9).
Assuntos
Cistos/cirurgia , Esplenopatias/cirurgia , Adolescente , Criança , Pré-Escolar , Cistos/diagnóstico , Feminino , Humanos , Achados Incidentais , Lactente , Masculino , Estudos Retrospectivos , Esplenopatias/diagnósticoRESUMO
The path-length spectra of mesoscopic systems including diffractive scatterers and connected to a superconductor are studied theoretically. We show that the spectra differ fundamentally from that of normal systems due to the presence of Andreev reflection. It is shown that negative path lengths should arise in the spectra as opposed to the normal system. To highlight this effect we carried out both quantum mechanical and semiclassical calculations for the simplest possible diffractive scatterer. The most pronounced peaks in the path-length spectra of the reflection amplitude are identified by the routes that the electron and/or hole travels.
RESUMO
Clinical and arthroscopic findings after knee joint injury were evaluated in 35 children aged 4-15 years. Arthroscopy revealed a rupture of the anterior cruciate ligament in 9 patients; two lesions were only partial. Eight children suffered from patellar dislocation. Eleven patients showed minimal synovial and cartilaginous lesions as the only cause of hemarthrosis, hydrarthrosis and clinical symptoms. Three had chondral lesions due to a dysplastic patella. The clinical diagnosis was confirmed in only 12 of 35 cases. Arthroscopic therapy was performed in 15 and open surgical intervention in 16 patients. Our results show that hemarthrosis and persisting symptoms after a knee trauma in children indicate a severe knee injury. The diagnostic procedure and treatment should be as ambitious as in adults.
Assuntos
Artroscopia , Traumatismos do Joelho/diagnóstico , Adolescente , Ligamento Cruzado Anterior/cirurgia , Lesões do Ligamento Cruzado Anterior , Cartilagem Articular/lesões , Cartilagem Articular/cirurgia , Criança , Pré-Escolar , Feminino , Hemartrose/diagnóstico , Hemartrose/cirurgia , Humanos , Instabilidade Articular/diagnóstico , Instabilidade Articular/cirurgia , Traumatismos do Joelho/cirurgia , Masculino , Meniscos Tibiais/cirurgia , Patela/lesões , Patela/cirurgia , Lesões do Menisco TibialRESUMO
INTRODUCTION: Although the early definitive closure of gastroschisis is possible in many cases, there is an ongoing discussion about the advantages of staged reduction. Different strategies and materials have been described to wrap the bowel for protection and reduce heat and fluid loss. The variety of devices ranges from prosthetic patches to biomaterials. We present use of the umbilical cord for temporary coverage in primarily irreducible gastroschisis. METHOD: After revision and reduction of as much gut as possible under constant monitoring of the bladder pressure, the remaining eviscerated intestine is covered by the longitudinally split umbilical cord. Over the following days the continued reduction of the bowel relies on gravity, assisted by progressive compression by the shrinking umbilical cord tissue. At 10 days after performing the umbilical cord flap, it is possible to close the fascia without complications using gentle pressure. RESULTS: Since 1991 we have used this umbilical cord flap for staged reduction in 17 infants (10 females, 7 males) with giant gastroschisis. There were no complications related to use of the umbilical cord flap, no infections or NEC episodes, and no mortality. Length of hospital stay was 5 weeks on average. In 3 patients the course was complicated by associated defects or an underlying malformation. CONCLUSION: Our experience confirms the advantage of a staged reduction in giant gastroschisis. The use of autogenic material such as the umbilical cord has advantages such as low infection rates and easy availability.
Assuntos
Gastrosquise/cirurgia , Cordão Umbilical/cirurgia , Fasciotomia , Feminino , Humanos , Recém-Nascido , Masculino , Retalhos CirúrgicosRESUMO
A comprehensive theory of electron spin resonance (ESR) for a Luttinger liquid state of correlated metals is presented. The ESR measurables such as the signal intensity and the linewidth are calculated in the framework of Luttinger liquid theory with broken spin rotational symmetry as a function of magnetic field and temperature. We obtain a significant temperature dependent homogeneous line broadening which is related to the spin-symmetry breaking and the electron-electron interaction. The result crosses over smoothly to the ESR of itinerant electrons in the noninteracting limit. These findings explain the absence of the long-sought ESR signal of itinerant electrons in single-wall carbon nanotubes when considering realistic experimental conditions.
RESUMO
In the last 10 years biofeedback training (BFT) has been used in 72 patients with anal continence disturbances following rectoanal agenesis, constipation, MMC, etc. Using the BF-method we treated 35 children with incontinence following rectoanal agenesis (5 infralevator, 30 supralevator). Visual analog feedback was used in the first 10 cases. Since 1982 simultaneous audiovisual analog signals have been preferred. The detailed analysis and personal followup over 6.5 years of these patients suggests that BFT improves the threshold of rectal sensation, voluntary contraction and thereby benefits anal continence.
Assuntos
Anus Imperfurado/reabilitação , Biorretroalimentação Psicológica/métodos , Condicionamento Psicológico , Incontinência Fecal/reabilitação , Adolescente , Criança , Pré-Escolar , Terapia Combinada , Feminino , Seguimentos , Humanos , MasculinoRESUMO
The suitability of fibrinogen gluing for prophylaxis of intraperitoneal adhesions was investigated experimentally. Small bowel slings, traumatized previously, were covered by a layer of fibrinogen 2-3 mm thick to see whether formation of adhesions could be prevented. In the experiments 50 rats of both sexes were observed over 21 days. Following mechanical traumatization of the terminal ileum the visceral peritoneum was coated with fibrinogen, whereas animals of the control group did not receive fibrinogen coating. Macroscopic and microscopic findings after 1, 3, 7, 14 and 21 days yielded the following results: 1. Fibrinogen dissolution and resorption occurred for 3-14 days following operation. 2. On autopsy, all animals of the control group showed massive, extended adhesions; two of the controls died on the 6th postoperative day from peritonitis. 3. None of the treated animals exhibited extended adhesions. 4. Histological examinations revealed regeneration of the injured serosa and healing of the bowel wall below the fibrinogen coating. 5. Fibrinogen applied to intact peritoneal serosa (without injury) is entirely resorbed without formation of adhesions.
Assuntos
Adesivo Tecidual de Fibrina/uso terapêutico , Doenças Peritoneais/prevenção & controle , Animais , Feminino , Adesivo Tecidual de Fibrina/administração & dosagem , Íleo/lesões , Masculino , Peritônio , Ratos , Aderências Teciduais/prevenção & controleRESUMO
Between 1969 and 1988, 191 children underwent operations for anorectal anomalies in the Pediatric Surgical Department of Mainz University Hospital. Ninety-six had deep and 84 had intermediate or high malformations; the type was unknown in 11. Of these patients 53 had impaired continence and 8 still have a protective colostoma. 37 of the remaining 45 children had check-ups and reoperations (5 were deep types). After reoperation there was full continence in 14 patients, partial continence in 11, persisting incontinence in 11 and one case could not be assessed. Our results recommend reoperation using modern surgical methods of patients with continence.
Assuntos
Anus Imperfurado/cirurgia , Incontinência Fecal/cirurgia , Complicações Pós-Operatórias/cirurgia , Criança , Pré-Escolar , Colostomia/métodos , Seguimentos , Humanos , Lactente , Recém-Nascido , ReoperaçãoRESUMO
Abdominal actinomycosis (AMC) is a rare infection in children. The appendix is the most common intra-abdominal organ involved. It presents as an undifferentiated mass, forming abscesses and fistulas in the right lower quadrant. The case of a 15-year-old girl with a AMC of the appendix detected by the pathologist after routine appendectomy is discussed. Long-term antibiotic treatment and follow-up by ultrasound and laboratory controls are necessary.
Assuntos
Abdome Agudo/etiologia , Actinomicose/cirurgia , Apendicite/microbiologia , Apendicite/cirurgia , Actinomicose/tratamento farmacológico , Actinomicose/patologia , Adolescente , Apendicectomia , Apendicite/patologia , Feminino , HumanosRESUMO
This is a report on a neonatal primary hyperparathyroidism (NPHPT) treated by total parathyroidectomy and autotransplantation of parathyroid tissue into the forearm musculature. Histologically, the glands were composed of a "chief cell hyperplasia" of the parathyroid tissue. Clinical manifestation in neonates and differential diagnosis of HPT are discussed. Indication for operation and surgical procedure are described.
Assuntos
Hiperparatireoidismo/cirurgia , Humanos , Recém-Nascido , Masculino , Glândulas Paratireoides/patologia , Glândulas Paratireoides/cirurgia , Glândulas Paratireoides/transplante , Transplante AutólogoRESUMO
Surgical and non-surgical conditions of the adrenal cortex and medulla are presented. Besides general principles of operative treatment (e.g. surgical approach, safe operative technique, bilateral exploration) specific aspects associated with this procedure in childhood are discussed. The perioperative management and pharmacotherapeutical preparation (e.g. hormonal substitution) are emphasized.
Assuntos
Doenças das Glândulas Suprarrenais/cirurgia , Glândulas Suprarrenais/cirurgia , Doenças das Glândulas Suprarrenais/diagnóstico , Neoplasias das Glândulas Suprarrenais/cirurgia , Glândulas Suprarrenais/anormalidades , Glândulas Suprarrenais/transplante , Hiperplasia Suprarrenal Congênita/cirurgia , Criança , Síndrome de Cushing/cirurgia , Diagnóstico por Imagem , Humanos , Hiperaldosteronismo/cirurgia , Recém-Nascido , Neoplasias de Tecido Nervoso/cirurgia , Feocromocitoma/cirurgia , Transplante AutólogoRESUMO
5 children with mesenteric cysts, 3 boys and 2 girls, aged 2 to 10 years, were admitted with acute abdominal pain. In adults the most common symptom is chronic abdominal pain whereas in children the onset of symptoms is acute due to intestinal obstruction. Sonography, performed in two patients, is the diagnostic method of choice. Excision of the cyst required resection of the small intestine in 2 patients, while simple enucleation was possible in 3. All 5 patients survived, and there have been neither complications nor recurrences. Early recognition and appropriate resection of these occasionally life-threatening malformations are associated with a good prognosis.
Assuntos
Cisto Mesentérico/patologia , Abdome Agudo/patologia , Criança , Pré-Escolar , Feminino , Humanos , Obstrução Intestinal/patologia , Linfangioma/patologia , Masculino , Mesentério/patologia , Neoplasias Peritoneais/patologia , UltrassonografiaRESUMO
For the purpose of an experimental study in which the three different types of pressure catheters most commonly used in anorectal manometry were compared, a Starling-resistance could be established. Under equal conditions the pressures could be changed in this resistance and the data obtained by using a membrane-catheter, an open-tip and an open-side-catheter were compared among one another and to the known ideal straight line. The open tip catheter measures the opening pressure and the recorded pressure does not necessarily reflect the pressure at the site of the tip hole. Because of its elastic and plastic characteristics, the membrane-catheter yielded the best results with prestretch of the membrane and with calibration before and after each study.
Assuntos
Canal Anal/fisiologia , Manometria/instrumentação , Reto/fisiologia , Cateterismo/instrumentação , Criança , Humanos , Manometria/métodos , Valores de ReferênciaRESUMO
We examine the density of states of an Andreev billiard and show that any billiard with a finite upper cutoff in the path length distribution P(s) will possess an energy gap on the scale of the Thouless energy. An exact quantum mechanical calculation for different Andreev billiards gives good agreement with the semiclassical predictions when the energy dependent phase shift for Andreev reflections is properly taken into account. Based on this new semiclassical Bohr-Sommerfeld approximation of the density of states, we derive a simple formula for the energy gap. We show that the energy gap, in units of Thouless energy, may exceed the value predicted earlier from random matrix theory for chaotic billiards.
RESUMO
This is a report on the treatment of anal incontinence by biofeedback conditioning. Since August 1982 9 children with incontinence (8 rectoanal agenesia, one Morbus Hirschsprung) were treated by simultaneous optical and acoustical analogous biofeedback conditioning. Training of sensitivity and voluntary contractions were performed and controlled electromanometrically. According to the pressure waves electrical alterations were transformed and feedback visually and acoustically. Results of the training of the maximal voluntary contraction are presented and the superiority of this method for the coordination of the anorectal sphincter function is stressed.