Pathologic Basis of Diseaseby Stanley L. Robbins is really the fourth edition of hisPathology. Appropriate updating and addition enhance the otherwise identical format, sequence, writing, and illustrations. So many medical students have benefited from this source that it may be the best known general book in the field. I recommend it even more now. Like his former texts, this will be enjoyed for its readability. He clearly lays out a great deal of information. When he includes minutiae, the reasons are clear and one feels that all the material is pertinent. Robbins keeps the whole field in perspective—that is, he does not dwell so long or so heavily on pathologic anatomy or pathogenesis as to tempt the reader to overlook clinical presentation or prognosis. A great strength of the subject of pathology is that it bonds strongly with many other medical sciences and specialties and thus occupies the

Pathologic Basis of Disease

Genevieve Lloyd has edited a comprehensive collection of learned critical discussions of Spinoza's philosophy, covering the intellectual context in which he worked and the influence of his thought, as well as the published works.

The political writings

We survey progress in the PCM field over the past five years, ranging from large-scale PCM demonstrations to materials improvements for high–temperature retention and faster switching. Both materials and new cell designs that support lower-power switching are discussed, as well as higher reliability for long cycling endurance. Two paths towards higher density are discussed: through 3D integration by the combination of PCM and 3D-capable access devices, and through multiple bits per cell, by understanding and managing resistance drift caused by structural relaxation of the amorphous phase. We also briefly survey work in the nascent field of brain-inspired neuromorphic systems that use PCM to implement non-Von Neumann computing.

Recent Progress in Phase-Change Memory Technology

Physics of the Switching Kinetics in Resistive Memories

Phase change materials play a key role in information technology. Here, the authors measure the crystal growth velocity in doped Ge2Sb2Te5 up to the melting temperature, exploiting the nanoscale dimensions and the fast thermal dynamics of a phase change memory cell.

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Crystal growth within a phase change memory cell.

The relationship between the polycrystalline nature of phase change materials (such as Ge2Sb2Te5) and the intermediate resistance states of phase change memory (PCM) devices has not been widely studied. A full understanding of such states will require knowledge of how polycrystalline grains form, how they interact with each other at various temperatures, and how the differing electrical (and thermal) characteristics within the grains and at their boundaries combine through percolation to produce the externally observed electrical (and thermal) characteristics of a PCM device. We address the first of these tasks (and introduce a vehicle for the second) by studying the formation of fcc polycrystalline grains from the as-deposited amorphous state in undoped Ge2Sb2Te5. We perform ex situ transmission electron microscopy membrane experiments and then match these observations against numerical simulation. Ramped-anneal experiments show that the temperature ramp-rate strongly influences the median grain size. By truncating such ramped-anneal experiments at various peak temperatures, we convincingly demonstrate that the temperature range over which these grains are established is quite narrow. Subsequent annealing at elevated temperature appears to change these established distributions of grain sizes only slightly. Our numerical simulator—which models nuclei formation through classical nucleation theory and then tracks the subsequent time- and temperature-dependent growth of these grains—can match these experimental observations of initial grain distributions and crystallization temperature both qualitatively and quantitatively. These simulations show that the particular narrow temperature range over which crystallization occurs shifts as a function of temperature ramp-rate, which allows us to quantify the lower portions of the time-temperature-transformation map for Ge2Sb2Te5. Future experiments and extensions of the simulator to investigate temperature-dependent interactions between neighboring grains, and to study nucleation from within the melt-quenched amorphous state, are discussed.

Observation and modeling of polycrystalline grain formation in Ge2Sb2Te5

Understanding the mechanics of the lung is necessary for investigating disease progression. Trachea mechanics comprises the vast majority of ex vivo airway tissue characterization despite distal ai...

https://www.physiology.org/doi/pdf/10.1152/japplphysiol.00090.2018

Mechanical properties of the airway tree: heterogeneous and anisotropic pseudoelastic and viscoelastic tissue responses.

Progressive airflow obstruction is a classical hallmark of chronic lung disease, affecting more than one fourth of the adult population. As the disease progresses, the inner layer of the airway wall grows, folds inwards, and narrows the lumen. The critical failure conditions for airway folding have been studied intensely for idealized circular cross-sections. However, the role of airway branching during this process is unknown. Here, we show that the geometry of the bronchial tree plays a crucial role in chronic airway obstruction and that critical failure conditions vary significantly along a branching airway segment. We perform systematic parametric studies for varying airway cross-sections using a computational model for mucosal thickening based on the theory of finite growth. Our simulations indicate that smaller airways are at a higher risk of narrowing than larger airways and that regions away from a branch narrow more drastically than regions close to a branch. These results agree with clinical observations and could help explain the underlying mechanisms of progressive airway obstruction. Understanding growth-induced instabilities in constrained geometries has immediate biomedical applications beyond asthma and chronic bronchitis in the diagnostics and treatment of chronic gastritis, obstructive sleep apnea and breast cancer.

On the Role of Mechanics in Chronic Lung Disease

https://escholarship.org/content/qt82t992zk/qt82t992zk.pdf?t=qbxpb8

Mechanics of pulmonary airways: Linking structure to function through constitutive modeling, biochemistry, and histology

In contrast to inert systems, living biological systems have the advantage to adapt to their environment through growth and evolution. This transfiguration is evident during embryonic development, when the predisposed need to grow allows form to follow function. Alterations in the equilibrium state of biological systems breed disease and mutation in response to environmental triggers. The need to characterize the growth of biological systems to better understand these phenomena has motivated the continuum theory of growth and stimulated the development of computational tools in systems biology. Biological growth in development and disease is increasingly studied using the framework of morphoelasticity. Here, we demonstrate the potential for morphoelastic simulations through examples of volume, area, and length growth, inspired by tumor expansion, chronic bronchitis, brain development, intestine formation, plant shape, and myopia. We review the systems biology of living systems in light of biochemical and optical stimuli and classify different types of growth to facilitate the design of growth models for various biological systems within this generic framework. Exploring the systems biology of growth introduces a new venue to control and manipulate embryonic development, disease progression, and clinical intervention.

/pdf/systems-biology-and-mechanics-of-growth-54c8k5tlxm.pdf

Mona Eskandari

Papers

Observation and modeling of polycrystalline grain formation in Ge2Sb2Te5

Mechanical properties of the airway tree: heterogeneous and anisotropic pseudoelastic and viscoelastic tissue responses.

On the Role of Mechanics in Chronic Lung Disease

Mechanics of pulmonary airways: Linking structure to function through constitutive modeling, biochemistry, and histology

Systems biology and mechanics of growth