Bryn Mawr College

About: Bryn Mawr College is a education organization based out in Bryn Mawr, Pennsylvania, United States. It is known for research contribution in the topics: Population & Social work. The organization has 2300 authors who have published 4257 publications receiving 141392 citations.

The Scherrer Formula for X-Ray Particle Size Determination

Abstract: An exact derivation of the Scherrer equation is given for particles of spherical shape, values of the constant for half-value breadth and for integral breadth being obtained. Various approximation methods which have been used are compared with the exact calculation. The tangent plane approximation of v. Laue is shown to be quite satisfactory, but some doubt is cast on the use of approximation functions. It is suggested that the calculation for the ellipsoidal particle based on the tangent plane approximation will provide a satisfactory basis for future work.

Two Faces of Power

Abstract: The concept of power remains elusive despite the recent and prolific outpourings of case studies on community power. Its elusiveness is dramatically demonstrated by the regularity of disagreement as to the locus of community power between the sociologists and the political scientists. Sociologically oriented researchers have consistently found that power is highly centralized, while scholars trained in political science have just as regularly concluded that in “their” communities power is widely diffused. Presumably, this explains why the latter group styles itself “pluralist,” its counterpart “elitist.”There seems no room for doubt that the sharply divergent findings of the two groups are the product, not of sheer coincidence, but of fundamental differences in both their underlying assumptions and research methodology. The political scientists have contended that these differences in findings can be explained by the faulty approach and presuppositions of the sociologists. We contend in this paper that the pluralists themselves have not grasped the whole truth of the matter; that while their criticisms of the elitists are sound, they, like the elitists, utilize an approach and assumptions which predetermine their conclusions. Our argument is cast within the frame of our central thesis: that there are two faces of power, neither of which the sociologists see and only one of which the political scientists see.

The Hierarchical Taxonomy of Psychopathology (HiTOP): A Dimensional Alternative to Traditional Nosologies

Abstract: The reliability and validity of traditional taxonomies are limited by arbitrary boundaries between psychopathology and normality, often unclear boundaries between disorders, frequent disorder co-occurrence, heterogeneity within disorders, and diagnostic instability. These taxonomies went beyond evidence available on the structure of psychopathology and were shaped by a variety of other considerations, which may explain the aforementioned shortcomings. The Hierarchical Taxonomy Of Psychopathology (HiTOP) model has emerged as a research effort to address these problems. It constructs psychopathological syndromes and their components/subtypes based on the observed covariation of symptoms, grouping related symptoms together and thus reducing heterogeneity. It also combines co-occurring syndromes into spectra, thereby mapping out comorbidity. Moreover, it characterizes these phenomena dimensionally, which addresses boundary problems and diagnostic instability. Here, we review the development of the HiTOP and the relevant evidence. The new classification already covers most forms of psychopathology. Dimensional measures have been developed to assess many of the identified components, syndromes, and spectra. Several domains of this model are ready for clinical and research applications. The HiTOP promises to improve research and clinical practice by addressing the aforementioned shortcomings of traditional nosologies. It also provides an effective way to summarize and convey information on risk factors, etiology, pathophysiology, phenomenology, illness course, and treatment response. This can greatly improve the utility of the diagnosis of mental disorders. The new classification remains a work in progress. However, it is developing rapidly and is poised to advance mental health research and care significantly as the relevant science matures. (PsycINFO Database Record