Many-body localization: stability and instability.

Rare regions with weak disorder (Griffiths regions) have the potential to spoil localization. We describe a non-perturbative construction of local integrals of motion (LIOMs) for a weakly interacting spin chain in one dimension, under a physically reasonable assumption on the statistics of eigenvalues. We discuss ideas about the situation in higher dimensions, where one can no longer ensure that interactions involving the Griffiths regions are much smaller than the typical energy-level spacing for such regions.

Diagonalization and Many-Body Localization for a Disordered Quantum Spin Chain.

We consider a weakly interacting quantum spin chain with random local interactions. We prove that many-body localization follows from a physically reasonable assumption that limits the extent of level attraction in the statistics of eigenvalues. In a Kolmogorov-Arnold-Moser-style construction, a sequence of local unitary transformations is used to diagonalize the Hamiltonian by deforming the initial tensor-product basis into a complete set of exact many-body eigenfunctions.

Intraoperative ultrasound is associated with clear lumpectomy margins for palpable infiltrating ductal breast cancer.

Objective: To evaluate the efficacy of intraoperative ultrasound in obtaining adequate surgical margins in women undergoing lumpectomy for palpable breast cancer.

Summary Background Data: Adequacy of surgical margins is a subject of debate in the literature for women undergoing breast-conserving therapy. The emerging technology of intraoperative ultrasound-guided surgery lends itself well to a prospective study evaluating surgical accuracy and margin status after lumpectomy.

Association of infiltrating lobular carcinoma with positive surgical margins after breast-conservation therapy.

Objective: To determine whether infiltrating lobular carcinoma (ILC) is associated with high positive-margin rates for single-stage lumpectomy procedures, and to define clinical, mammographic, or histologic characteristics of ILC that might influence the positive-margin rate, thereby affecting treatment decisions.

Summary Background Data: Infiltrating lobular cancer represents approximately 10% of all invasive breast carcinomas and is often poorly defined on gross examination.

Methods: A group of 47 patients with biopsy-proven ILC undergoing breast-conservation therapy (BCT) at the University of Virginia Health Sciences Center between 1975 and 1999 was compared with a group of 150 patients with infiltrating ductal cancer undergoing BCT during the same time period.

Interventions to reduce decibel levels on patient care units.

The University of Virginia Health System inpatient satisfaction survey identified noise as the most important irritant to surgical inpatients. Analysis of the level and pattern of noise on patient floors and intensive care units was done with baseline measurements followed by then two separate interventions: 1) education of nursing and physician staff 2) closing patient room doors. A decibel meter (M-27 Dosimeter) recorded the noise level over 24 hours.

The mechanics underlying laparoscopic intra-abdominal surgery for obese patients.

Any surgeon experienced with a laparoscopic approach to intra-abdominal surgery on morbidly obese patients is aware of the increased difficulty associated with the patients' obesity. We present a study of the mechanics of laparoscopic surgery that explains the difficulty subjectively experienced in terms of the decreased sensitivity felt by the surgeon as a result of the increased thickness of the abdominal wall and increasing force required for the repositioning of the tip of the operating instrument. We propose that the placement and angling of the trocar in the abdominal wall are of paramount importance in the successful and safe completion of laparoscopic procedures in obese patients.

Kartagener's syndrome: a genetic defect affecting the function of cilia.

Kartagener's syndrome, originally described as situs inversus, bronchiectasis, and sinusitis, has recently been demonstrated to be the result of a genetic defect manifest in structural and functional abnormalities of cilia. The absence of dynein arms in the cilia of patients with Kartagener's syndrome has been found be several investigators, utilizing electron microscopy. The cilia of four siblings, two with the syndrome and two without it, were studied by this method.

Modeling the climatic response to orbital variations.

According to the astronomical theory of climate, variations in the earth's orbit are the fundamental cause of the succession of Pleistocene ice ages. This article summarizes how the theory has evolved since the pioneer studies of James Croll and Milutin Milankovitch, reviews recent evidence that supports the theory, and argues that a major opportunity is at hand to investigate the physical mechanisms by which the climate system responds to orbital forcing. After a survey of the kinds of models that have been applied to this problem, a strategy is suggested for building simple, physically motivated models, and a time-dependent model is developed that simulates the history of planetary glaciation for the past 500,000 years.

Variations in the Earth's Orbit: Pacemaker of the Ice Ages.

1) Three indices of global climate have been monitored in the record of the past 450,000 years in Southern Hemisphere ocean-floor sediments. 2) Over the frequency range 10(-4) to 10(-5) cycle per year, climatic variance of these records is concentrated in three discrete spectral peaks at periods of 23,000, 42,000, and approximately 100,000 years. These peaks correspond to the dominant periods of the earth's solar orbit, and contain respectively about 10, 25, and 50 percent of the climatic variance.