Suppression of Alfvén Modes on the National Spherical Torus Experiment Upgrade with Outboard Beam Injection.

In this Letter we present data from experiments on the National Spherical Torus Experiment Upgrade, where it is shown for the first time that small amounts of high pitch-angle beam ions can strongly suppress the counterpropagating global Alfvén eigenmodes (GAE). GAE have been implicated in the redistribution of fast ions and modification of the electron power balance in previous experiments on NSTX. The ability to predict the stability of Alfvén modes, and developing methods to control them, is important for fusion reactors like the International Tokamak Experimental Reactor, which are heated by a large population of nonthermal, super-Alfvénic ions consisting of fusion generated α's and beam ions injected for current profile control. We present a qualitative interpretation of these observations using an analytic model of the Doppler-shifted ion-cyclotron resonance drive responsible for GAE instability which has an important dependence on k_{⊥}ρ_{L}. A quantitative analysis of this data with the hym stability code predicts both the frequencies and instability of the GAE prior to, and suppression of the GAE after the injection of high pitch-angle beam ions.

Scintillator based energetic ion loss diagnostic for the National Spherical Torus Experiment.

A scintillator based energetic ion loss detector has been built and installed on the National Spherical Torus Experiment (NSTX) [Synakowski et al., Nucl. Fusion 43, 1653 (2000)] to measure the loss of neutral beam ions. The detector is able to resolve the pitch angle and gyroradius of the lost energetic ions. It has a wide acceptance range in pitch angle and energy, and is able to resolve the full, one-half, and one-third energy components of the 80 keV D neutral beams up to the maximum toroidal magnetic field of NSTX. Multiple Faraday cups have been embedded behind the scintillator to allow easy absolute calibration of the diagnostic and to measure the energetic ion loss in several ranges of pitch angle with good time resolution. Several small, vacuum compatible lamps allow simple calibration of the scintillator position within the field of view of the diagnostic's video camera.

Interaction between the Rous sarcoma virus transforming protein and two cellular phosphoproteins: analysis of the turnover and distribution of this complex.

The transforming protein of Rous sarcoma virus (RSV), pp60src, was previously shown to associate with two cellular proteins of Mr 90,000 and 50,000 in RSV-transformed chicken cells. In this report, we demonstrate that this interaction is specific for a discrete population of pp60src molecules. Newly synthesized pp60src was found to preferentially associate with pp90 and pp50 to form a short-lived complex. The half-life of this complex varied from 9 to 15 min in cells transformed by nondefective strains of RSV. This interaction between pp60src, pp50, and pp90 took place in a soluble fraction of the cell, and the complex-bound pp60src molecules were not phosphorylated on tyrosine. These results suggest that pp90 and pp50 may be involved in the processing of pp60src molecules before the association of pp60src with the plasma membrane. The kinetics of dissociation of this complex were shown to be altered in cells infected with viruses containing a temperature-sensitive defect in the src gene. When cells infected with these viruses were grown at the nonpermissive temperature, more than 90% of the pp60src molecules were associated with pp90 and pp50, and little or no dissociation was observed in a 3-h chase period. These results suggest that mutations in the src gene which affect the transforming activity of pp60src also affect the stability of the interaction of pp60src with pp90 and pp50.

Plasma diagnostics in spherical tokamaks with silicon charged-particle detectors.

Detection of charged fusion products, such as protons and tritons resulting from D(d, p) t reactions, can be used to determine the position and time dependent fusion reaction rate profile in spherical tokamak plasmas with neutral beam heating. We have developed a prototype instrument consisting of 6 ion-implanted-silicon surface barrier detectors combined with collimators in such a way that each detector can accept 3 MeV protons and 1 MeV tritons and thus provides a curved view across the plasma cross section. The combination of the results from all six detectors will provide information on the spatial distribution of the fusion reaction rate. The expected time resolution of about 1 ms makes it possible to study changes in the reaction rate due to slow variations in the neutral beam density profile, as well as rapid changes resulting from MHD instabilities. Details of the new instrument, its data acquisition system, simulation results, and electrical noise testing results are discussed in this paper. First experimental data are expected to be taken during the current experimental campaign at NSTX-U.

Faraday-cup-type lost fast ion detector on Heliotron J.

A Faraday-cup type lost-fast ion probe (FLIP) has been designed and installed in Heliotron J for the purpose of the studies of interaction between fast ions and MHD instabilities. The FLIP can measure the co-going fast ions whose energy is in the range of 1.7-42.5 keV (proton) and pitch angle of 90∘-140∘, especially for fast ions having the injection energy of neutral beam injection (NBI). The FLIP successfully measured the re-entering passing ions and trapped lost-fast ions caused by fast-ion-driven energetic particle modes in NBI heated plasmas.

Reduction of endotoxin-induced inflammation of the middle ear by polymyxin B.

Endotoxin (ET) is an aggregate of lipo-oligosaccharide and protein found in the cell wall of gram-negative bacteria. A potent mediator of inflammatory responses, ET has been detected in middle ear effusions from patients with otitis media with effusion and chronic suppurative otitis media and used to induce inflammation of the middle ear mucosa and disruption of mucociliary transport in experimental animals. Polymyxin B, a polypeptide antibiotic, has been shown to bond to and inactivate the ET molecule. This study investigated the efficacy of polymyxin B as a modulator of the inflammatory response to endotoxin in the middle ear. In a guinea pig model, cellular infiltrate, effusion volume, and mucosal edema in response to ET were reduced in the presence of polymyxin B. These results suggest a potential role for the use of polymyxin B in the management of middle ear effusion.

Effects of bacterial endotoxin applied to the guinea pig cochlea.

The ototoxic potential of bacterial endotoxin present in middle ear effusions was evaluated by inoculating endotoxin solutions of 10 micrograms/mL or 1000 micrograms/mL directly into the scala tympani of the guinea pig cochlea. Median auditory brainstem response threshold shifts of 12.5 and 20 dB were observed in the experimental ears exposed to the higher dose at days 2 and 4, respectively, with gradual improvement to near baseline by day 28. Histologic examination revealed inflammatory infiltrates in the scala tympani and scala vestibuli of several of these cochleas. The lower concentration, closer to that found in human effusions, elicited no significant loss of hearing and a milder inflammatory response. It is concluded that brief exposure of the cochlea to endotoxin from middle ear effusions is insufficient to cause hearing loss. Under chronic conditions, however, persistent inflammation within the cochlea may result in a sensorineural deficit.

Pediatric tracheotomies: changing indications and outcomes.

OBJECTIVE/HYPOTHESIS: To study the outcomes and complications associated with pediatric tracheotomy, as well as the changing trend in indications and outcomes since 1970. STUDY DESIGN: Retrospective chart review at a major tertiary care children's hospital. METHODS: On children who underwent tracheotomy at Children's Hospital of the King's Daughters (Norfolk, VA) between 1988 and 1998, inpatient and outpatient records were reviewed. Of 218 tracheotomies, sufficient data were available on 204. Indications for tracheotomy were placed into the following six groups: craniofacial abnormalities (13%), upper airway obstruction (19%), prolonged intubation (26%), neurological impairment (27%), trauma (7%), and vocal fold paralysis (7%). RESULTS: The average age at tracheotomy was 3.2 +/- 0.6 years. Although the prolonged intubation group was significantly younger than all others, the neurological impairment and trauma groups were significantly older. Decannulation was accomplished in 41%. Time to decannulation was significantly higher in the neurological impairment and prolonged intubation groups, but was significantly shorter in the craniofacial group. Complications occurred in 44%. Overall mortality was 19%, with a 3.6% tracheotomy-related death rate. Comparison of our series to other published series of pediatric tracheotomies since 1970 shows fewer being performed for airway infections and more for chronic diseases, with a corresponding increase in duration of tracheotomy and decreased decannulation rates. CONCLUSIONS: Tracheotomy is a procedure performed with relative frequency at tertiary care children's hospitals. While children receiving a tracheotomy have a high overall mortality, deaths are usually related to the underlying disease, not the tracheotomy itself.

The effect of very early cleft palate closure on the need for ventilation tubes in the first years of life.

The otologic consequences associated with cleft palates are well known. Closure of palatal clefts within the first weeks of life has many potential benefits, including improved feeding and cosmesis. The potential otologic benefits of very early closure are not known. Eighteen newborns have undergone closure of their palatal clefts within the first month of life with subsequent otolaryngology follow-up through our craniofacial center. Thirteen (72%) of the 18 still required placement of ventilation tubes during their first 3 years of life because of persistent effusion (for more than 120 days) or recurrent infection (more than four episodes in 6 months or more than six episodes in 12 months). Very early cleft palate closure may not significantly alter the need for ventilation tubes in children with palatal clefts.

Tube placement: a prospective, randomized double-blind study.

Bilateral myringotomy with tympanostomy tube placement is the second most frequently performed pediatric surgical procedure, next to circumcision. Postoperative pain relief for children undergoing this procedure has been an ongoing concern. The authors undertook a prospective, randomized, double-blind, placebo-controlled clinical study in 200 consecutive children to investigate the efficacy of oral acetaminophen, acetaminophen with codeine, ibuprofen, and placebo administered preoperatively in relieving postoperative pain in children undergoing this procedure. All children received topical analgesia consisting of antibiotic eardrops mixed with 4% lidocaine intraoperatively. There was no significant difference in postoperative pain score between the four groups (P > 0.4447). Thus it is likely that the intraoperative administration of antibiotic eardrops mixed with 4% lidocaine is all that is required to alleviate postoperative pain in children undergoing myringotomy with tympanostomy tube placement. Preoperative oral analgesics are apparently of little added benefit.

Handheld metal detector confirmation of radiopaque foreign bodies in the esophagus.

OBJECTIVE: To examine the utility of handheld metal detectors in confirming the position of radiopaque foreign bodies in the esophagus before delayed endoscopic removal. DESIGN: Prospective study of patients evaluated between June 1, 1997, and August 31, 1999. SETTING: Tertiary pediatric referral center. PATIENTS: Twenty-six of 139 children presenting consecutively for evaluation of esophageal foreign bodies met eligibility criteria and completed the study protocol. Inclusion in the study was contingent on a delay of at least 6 hours from the time of diagnosis to the time of endoscopic removal. All patients underwent both radiographic evaluation and handheld metal detector scanning of the chest and abdomen on presentation and immediately before endoscopic removal. RESULTS: All patients evaluated during the study period had coins lodged within the esophagus. Handheld metal detector scanning accurately confirmed this position before endoscopic removal in all cases. CONCLUSION: Our data suggest that handheld metal detectors may obviate the need for repeated radiographs in patients whose foreign bodies cannot be removed at presentation.

Management of dysphagia in inclusion body myositis.

Inclusion body myositis is an inflammatory myopathy in which dysphagia has been considered a rare finding. However, recent literature finds dysphagia an increasingly common symptom as more cases of inclusion body myositis are identified. Unlike some inflammatory myopathic disorders, inclusion body myositis is resistant to treatment with corticosteroids, and therefore, the otolaryngologist may be consulted regarding surgical options for relief of dysphagia. A patient is described in whom severe progressive dysphagia associated with inclusion body myositis developed. Impaired pharyngeal wall motion and cricopharyngeal achalasia were demonstrated by videofluoroscopic evaluation, and the patient was successfully treated by cricopharyngeal myotomy. The pathophysiologic nature of inclusion body myositis and the mechanisms of cervical dysphagia in the inflammatory myopathies are reviewed.

Resistant bacteria in middle ear fluid at the time of tympanotomy tube surgery.

This study was performed to determine the prevalence of resistant Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis isolated from middle ear fluid of children undergoing placement of ventilation tubes. The extent of resistance to commonly prescribed antibiotics and the risk factors associated with this resistance were also examined. Children who had fluid present in their middle ears at the time of ventilation tube placement from May 1996 to May 1997 were included in the study. Middle ear fluid was plated onto culture media in the operating room, and antimicrobial resistance of cultured organisms was ascertained. Risk factors for this resistance were determined from the medical history and analyzed. Cultures of 244 patients (355 ears) were positive for organisms in 29.6%. Penicillin resistance was found in 38.2% of S pneumoniae cultures. Beta-lactamase production was found in 65.1% and 100% of H influenzae and M catarrhalis specimens, respectively. Risk factor analysis revealed young age, day care attendance, and number of antibiotic courses to most reliably predict the presence of resistant microorganisms.

Aerodigestive tract foreign bodies in the older child and adolescent.

This study was undertaken in order to establish the incidence of aerodigestive tract foreign body accidents among older children and adolescents, and to investigate the circumstances surrounding these events. A review of patients treated over a 5-year period identified 367 children from whom aerodigestive tract foreign bodies were removed. Seventeen percent of these patients were 5 years of age or older. Among these children, 88% aspirated nonfood items, half of which were school supplies; 78% of the group 5 years old and under aspirated food items. Among older children with esophageal foreign bodies, 31% had food impactions, compared with 7% in the younger group; 70% of these children had a history of some anatomic abnormality of the esophagus. These data suggest that older children and adolescents represent a distinct group of patients at risk for foreign body accidents. Pediatricians and parents of children in this age group should discourage the practice of using the oral cavity as a repository for school supplies, and should stress the need for adequate preparation and mastication of food, particularly among children with esophageal abnormalities.

Endobronchial tumors in children: an uncommon clinical entity.

We performed a retrospective chart review of 10 children in whom endobronchial tumors were diagnosed in a tertiary-care children's medical center from 1988 to 1998. Of the 10 patients, 6 were male and 4 were female (8 white, 1 Hispanic, 1 African American). The mean age at presentation was 5.2 years. Eight tumors were benign, and 2 were malignant; 4 were on the right side, 3 were on the left side, and 3 were bilateral. Histologic findings included 3 bronchial papillomas, 3 inflammatory masses, 1 endobronchial hemangioma, 1 leiomyoma, 1 mucoepidermoid carcinoma, and 1 bronchial carcinoid. Endobronchial tumors in children are a rare disorder. The diagnosis requires a high index of suspicion in children with atypical or chronic respiratory complaints. Newer adjuvant medical therapies and surgical innovations offer improved disease control in these patients, and a multidisciplinary approach is often warranted.

Recurrent respiratory papillomatosis of the larynx: current diagnosis and treatment.

Treating children with recurrent respiratory papillomatosis can be very rewarding as more information is learned about human papillomavirus. The future goals are reducing the morbidity and mortality of this disease process. The establishment of the national recurrent respiratory papillomatosis patient registry and coordinated efforts between basic scientists involved in human papillomavirus research and clinicians involved in the treatment of recurrent respiratory papillomatosis should aid the endeavor.

Evaluation of swallowing disorders in children.

Congenital anomalies of the head and neck and congenital and acquired neuromuscular disorders in children are frequently associated with dysfunctional feeding and swallowing. Determination of the affected phase of swallowing and appropriate guidelines for feeding depend on detailed clinical assessment at the bedside and radiographic evaluation by videofluoroscopy. Fiberoptic and rigid endoscopic examination of the airway are useful in the diagnosis of subtle structural abnormalities that are not appreciated on physical and radiologic examination. Once a diagnosis is established, repeating the evaluation process helps to assess the outcome of therapeutic and surgical intervention.

Fetal rhabdomyoma of the posterior cervical triangle.

Rhabdomyoma is an uncommon benign tumor, with the majority arising from cardiac muscle. Seventy to 90% of extracardiac rhabdomyomas are found in the head and neck region, usually within the upper aerodigestive tract. The case of a 7-month-old boy with an enlarging posterior triangle neck mass found to be fetal rhabdomyoma is presented. This location is quite rare for benign rhabdomyoma, with previous literature search showing overwhelming predilection for the upper aerodigestive tract.

Pediatric tonsillectomy and adenoidectomy procedures.

The most common pediatric surgical procedures performed in the United States today are tonsillectomies and adenoidectomies (T&A). Surgical team members must be highly trained and efficient to ensure optimal patient outcomes, reduce surgical costs, and decrease the risk and potential complications inherent in T&A procedures. The authors review current surgical indications for T&A procedures; recommended preoperative, intraoperative, and postoperative patient care; and the management of potential complications.

Investigating fusion plasma instabilities in the Mega Amp Spherical Tokamak using mega electron volt proton emissions (invited).

The proton detector (PD) measures 3 MeV proton yield distributions from deuterium-deuterium fusion reactions within the Mega Amp Spherical Tokamak (MAST). The PD's compact four-channel system of collimated and individually oriented silicon detectors probes different regions of the plasma, detecting protons (with gyro radii large enough to be unconfined) leaving the plasma on curved trajectories during neutral beam injection. From first PD data obtained during plasma operation in 2013, proton production rates (up to several hundred kHz and 1 ms time resolution) during sawtooth events were compared to the corresponding MAST neutron camera data. Fitted proton emission profiles in the poloidal plane demonstrate the capabilities of this new system.