Percolating through networks of random thresholds: finite temperature electron tunneling in metal nanocrystal arrays.

We investigate how temperature affects transport through large networks of nonlinear conductances with distributed thresholds. In monolayers of weakly coupled gold nanocrystals, quenched charge disorder produces a range of local thresholds for the onset of electron tunneling. Our measurements delineate two regimes separated by a crossover temperature T*.

A prospective, controlled study assessing the effect of lopinavir on amprenavir concentrations boosted by ritonavir.

In a controlled, prospective study, the efficacy of ritonavir 200 mg twice daily (bid) in inhibiting the decrease of amprenavir plasma concentrations caused by co-administration of lopinavir was assessed. Twelve HIV-seropositive patients were enrolled, and nine patients completed the 28-day study. At day 14, plasma concentrations of amprenavir 600 mg bid and ritonavir 200 mg bid were determined over 12 h.

Response to highly active antiretroviral therapy strongly predicts outcome in patients with AIDS-related lymphoma.

Background: AIDS-related lymphoma (ARL) remains a frequent complication of HIV infection. We analyzed the outcome of patients with ARL with respect to the use and efficacy of highly active antiretroviral therapy (HAART) and to potential prognostic factors.

Methods: This multicenter cohort study included patients with systemic ARL diagnosed between 1990-2001.

Therapy with atazanavir plus saquinavir in patients failing highly active antiretroviral therapy: a randomized comparative pilot trial.

Objectives: To assess the safety, efficacy of atazanavir (400 and 600 mg)/saquinavir (1200 mg) once daily versus ritonavir/saquinavir (400 mg/400 mg) twice daily with two nucleoside reverse transcriptase inhibitors (NRTIs) in highly active antiretroviral therapy failure.

Design And Methods: Randomized, multinational, 48-week, pilot trial with antiretroviral-experienced patients having at least 1000 HIV-1 RNA copies/ml, 100 x 106 CD4 cells/l (75 x 106 cells/l without AIDS diagnosis) and virological response to a prior regimen. Efficacy was evaluated by HIV-1 RNA and CD4 cell changes from baseline to 48 weeks.

Convection in horizontally vibrated granular material.

We report observations of convective motion in a container filled with granular material when it is vibrated in the horizontal direction. We find that the roughness of the boundaries and the container dimensions play an important role in determining the shape and number of the convection cells. When the container bottom and lateral walls are rough, the system typically exhibits four counter-rotating rolls stacked in two pairs on top of each other; for very low filling height, it is possible to observe a single row of rolls arranged laterally along the bottom of the container.

Introduction to the focus issue on granular materials.

In a review paper [H. M. Jaeger, S.

Conducting nanowires built by controlled self-assembly of amyloid fibers and selective metal deposition.

Recent research in the field of nanometer-scale electronics has focused on the operating principles of small-scale devices and schemes to realize useful circuits. In contrast to established "top-down" fabrication techniques, molecular self-assembly is emerging as a "bottom-up" approach for fabricating nanostructured materials. Biological macromolecules, especially proteins, provide many valuable properties, but poor physical stability and poor electrical characteristics have prevented their direct use in electrical circuits.

Force distributions in three-dimensional compressible granular packs.

We present an experimental investigation of the probability distribution of normal contact forces, P(F), at the bottom boundary of static three-dimensional packings of compressible granular materials. We find that the degree of deformation of individual grains plays a large role in determining the form of this distribution. For small amounts of deformation we find a small peak in P(F) below the mean force with an exponential tail for forces larger than the mean force.

Stress transmission through three-dimensional ordered granular arrays.

We measure the local contact forces at both the top and bottom boundaries of three-dimensional face-centered-cubic and hexagonal-close-packed granular crystals in response to an external force applied to a small area at the top surface. Depending on the crystal structure, we find markedly different results which can be understood in terms of force balance considerations in the specific geometry of the crystal. Small amounts of disorder are found to create additional structure at both the top and bottom surfaces.

Clinical results of carotid artery stenting with a nitinol self-expanding stent (SMART stent).

Our objective was to assess the technical feasibility and the clinical results of internal carotid artery (ICA) stenting using a nitinol self-expanding stent (SMART stent). In 13 patients 13 high-grade stenoses of the internal carotid artery were treated via an implantation of a SMART stent. In all cases a predilation of the stenosis and a postdilation within the stent were performed.

Risk factors for the HIV-associated lipodystrophy syndrome in a closed cohort of patients after 3 years of antiretroviral treatment.

Objective: To identify prevalence and risk factors associated with the HIV-associated lipodystrophy syndrome (HIVLD) after 3 years of antiretroviral therapy, to investigate the diagnostic value of anthropometric measures and to assess the impact of HIVLD on quality of life.

Design And Methods: A prospective, cross-sectional, multicentre, observational, cohort study was performed in 27 German teaching hospitals, nonacademic hospitals and private practices. A total of 221 HIV-positive patients commencing antiretroviral therapy between July and September 1996 were studied.

Carotid artery stenting protected with an emboli containment system.

Background And Purpose: Fear of distal embolization and stroke has aroused concern regarding carotid stenting. Devices to protect the cerebral circulation may make carotid stenting safer.

Methods: A multidisciplinary study group tested a balloon occlusion-aspiration emboli entrapment device in conjunction with carotid stenting.

Cerebral ischemia detected with diffusion-weighted MR imaging after stent implantation in the carotid artery.

Background And Purpose: Concern regarding the safety of stent implantation in the carotid artery exists because of the risk of cerebral embolization during the procedure. The purpose of this prospective study was to determine the incidence of new areas of cerebral ischemia, as detected by using diffusion-weighted MR imaging after stent implantation in the carotid artery.

Methods: Diffusion-weighted MR imaging of the brain was performed in 67 patients with 70 high-grade stenoses of the carotid artery before and 24 hours after stent implantation.

Clinical results of cerebral protection with a filter device during stent implantation of the carotid artery.

Purpose: To assess the technical feasibility and the clinical results of cerebral protection with the Angioguard emboli-capture guidewire system during carotid artery stenting (CAS) for high-grade stenoses.

Methods: In 20 patients 20 stenoses of the internal carotid artery were treated with stent implantation. In all patients diffusion-weighted (DW) magnetic resonance imaging (MRI) of the brain was performed before and 24 hr after the procedure.

Cardiology and AIDS--HAART and the consequences.

Since the introduction of highly active antiretroviral therapy (HAART), AIDS has become a treatable disease. A steep decline in morbidity and mortality has been observed in most western countries. The HIV epidemic is now moving into middle-aged populations which are already at increased risk for cardiovascular disease.

Hierarchical self-assembly of metal nanostructures on diblock copolymer scaffolds.

Self-assembly is emerging as an elegant, 'bottom-up' method for fabricating nanostructured materials. This approach becomes particularly powerful when the ease and control offered by the self-assembly of organic components is combined with the electronic, magnetic or photonic properties of inorganic components. Here we demonstrate a versatile hierarchical approach for the assembly of organic-inorganic, copolymer-metal nanostructures in which one level of self-assembly guides the next.

Digital chest radiography with a large-area flat-panel silicon X-ray detector: clinical comparison with conventional radiography.

This was a radiologists' preference study to compare a digital chest radiography system that utilizes a large-area silicon flat-panel detector with conventional radiography for visualizing anatomic regions of the chest. Conventional and digital posteroanterior (PA) and lateral chest radiographs were obtained in 115 patients. The PA and lateral image pairs were compared independently by three radiologists rating the overall appearance, 11 anatomic regions in the PA, and 9 in the lateral views.

Diffusion-weighted MR imaging after angioplasty or angioplasty plus stenting of arteries supplying the brain.

Background And Purpose: There has been concern regarding the safety of revascularization procedures of vessels supplying the brain vessels because of the risk of cerebral embolization during the procedure. We have observed a high incidence of hyperintense lesions on diffusion-weighted MR images of the brain after stenting at the carotid bifurcation. The hypothesis of this study is that diffusion-weighted MR imaging of the brain can reveal new diffusion abnormalities after angioplasty or angioplasty plus stenting of arteries supplying the brain, other than at the carotid bifurcation.

Convection in a fully immersed granular slurry.

Using vertical vibrations, we have induced convection in a granular system completely immersed in fluid inside a cylindrical container. Convection is established in a single convection roll, which carries the material upward in the center and downward along the side walls of the container. We measure the rise times of tracer particles embedded in the medium at various depths along the central axis of the system.

Effective models for medical and health response coordination: summary and action plan.

Introduction: To effectively respond to this relatively new, complex mandate, it is essential to find effective models of coordination to ensure that medical and health services can meet the standards now expected in a disaster situation. This theme explored various models, noting both the strengths that can be built on and the weaknesses that still need to be overcome.

Methods: Details of the methods used are provided in the preceding paper.

Force distributions in three-dimensional granular assemblies: effects of packing order and interparticle friction.

We present a systematic investigation of the distribution of normal forces at the boundaries of static packings of spheres. A method for the efficient construction of large hexagonal-close-packed crystals is introduced and used to study the effect of spatial ordering on the distribution of forces. Under uniaxial compression we find that the form for the probability distribution of normal forces between particles does not depend strongly on crystallinity or interparticle friction.

Congenital absence of the internal carotid artery and the basilar artery with persistent trigeminal artery associated with coarctation of the aorta.

We report a case of congenital absence of the cervical and petrous part of the left internal carotid artery, the middle and proximal part of the basilar artery, and the V4 segment of the left vertebral artery associated with a left persistent trigeminal artery and a coarctation of the aorta. The left cerebral vessels are supplied via the anterior communicating artery and the left persistent trigeminal artery. The coexisting coarctation of the aorta led to a subclavian steal phenomenon.