Functional clustering algorithm for the analysis of dynamic network data.

We formulate a technique for the detection of functional clusters in discrete event data. The advantage of this algorithm is that no prior knowledge of the number of functional groups is needed, as our procedure progressively combines data traces and derives the optimal clustering cutoff in a simple and intuitive manner through the use of surrogate data sets. In order to demonstrate the power of this algorithm to detect changes in network dynamics and connectivity, we apply it to both simulated neural spike train data and real neural data obtained from the mouse hippocampus during exploration and slow-wave sleep. Using the simulated data, we show that our algorithm performs better than existing methods. In the experimental data, we observe state-dependent clustering patterns consistent with known neurophysiological processes involved in memory consolidation.

Managing the patient with perforated intrathoracic esophagus.

The thoracic perioperative specialty team members at Inova Fairfax Hospital, Falls Church, Va, designed guidelines to improve the management of patients with esophageal perforations. They performed a retrospective analysis of 41 patients who were diagnosed with thoracic esophageal perforations from Sept 1, 1979, through Sept 1, 1996. The review affirmed their philosophy of aggressive, surgical intervention for perforations, particularly for patients diagnosed early (i.e., within 24 hours). The process of examining and communicating the results among OR nurses, anesthesia care providers, and surgeons resulted in the increased efficiency and appropriateness with which patients were incorporated into the hospital's surgical and medical treatment groups.

Descending cervical mediastinitis.

Descending cervical mediastinitis is an uncommonly reported presentation of infection originating in the head or neck and descending into the mediastinum, which is fraught with impressive morbidity and mortality rates of 30% to 40% or more. We present the INOVA-Fairfax-Alexandria Hospital experience with descending cervical mediastinitis, January 1, 1986, to April 1, 1997; in addition we review the English-language medical and surgical literature with regard to this entity. Computed tomography and magnetic resonance imaging serve to aid both diagnosis and management. The application of broad-spectrum antibiotics should initially be empiric, with an eye to coverage of mixed aerobic and anaerobic infections. Definitive treatment mandates early and aggressive surgical intervention. All affected tissue planes, cervical and mediastinal, must be widely debrided, often leaving them open for frequent packing and irrigation. The treating physician must remain always alert to the further extension of infection, which, if it occurs, must be further debrided and drained. Tracheostomy serves a dual role of further opening cervical fascial planes and securing an often compromised airway.

Bilateral lung volume reduction surgery.

A new surgical approach, bilateral lung volume reduction surgery (LVRS), offers hope for select patients with chronic pulmonary emphysema (CPE). Bilateral LVRS procedures involve excision of emphysematous alveoli, which results in a 20% to 30% reduction in the volume of each lung. The goal of LVRS is to improve the respiratory mechanics of patients with CPE by reexpanding functional lung tissue compressed by overdistended emphysematous alveoli, restoring diaphragmatic mobility, and improving the bellows function of the chest wall structures. Patients undergoing bilateral LVRS procedures experience relief from chronic dyspnea and may note improved pulmonary functions and better quality of life.