Doctors who perform operations. A study on in-hospital surgery in four diverse geographic areas (first of two parts)

The generous supply of surgeons in the United States stimulated a study of their operative work based on all operations performed by all physicians in hospitals of four geographic areas. Each operation was assigned a California Relative Value to permit work-load comparisons between specialties and practices. General practitioners constituted more than one quarter of physicians who performed operations but accounted for less than one tenth of total work. Surgical specialists, about half the physicians in the study, performed about 80 per cent of total operative work. Work loads of surgical specialists varied by certification, specialty, age and practice organization status. We conclude that far too many physicians perform surgical operations and that work loads of surgical specialists are modest. Calculations involving reallocation of operative work loads suggest that the total volume of operations in this study could have been handled by a substantially smaller cadre of busier surgical specialists.     

Null hypothesis significance testing: A review of an old and continuing controversy.

Null hypothesis significance testing (NHST) is arguably the most widely used approach to hypothesis evaluation among behavioral and social scientists. It is also very controversial. A major concern expressed by critics is that such testing is misunderstood by many of those who use it. Several other objections to its use have also been raised. In this article the author reviews and comments on the claimed misunderstandings as well as on other criticisms of the approach, and he notes arguments that have been advanced in support of NHST. Alternatives and supplements to NHST are considered, as are several related recommendations regarding the interpretation of experimental data. The concluding opinion is that NHST is easily misunderstood and misused but that when applied with good judgment it can be an effective aid to the interpretation of experimental data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comments on The Brain Watchers.

Comments on The Brain Watchers by M. L. Gross (see record 1964-04809-000), which presents a documented account of application of psychological tests, mostly personality, in industry and education at all levels. The present author argues that Gross presents his case with obvious hostility, and that exaggerations, sweeping generalities, and half-truths are found throughout the book and may tempt many serious psychologists (as human beings) to reject him outright. It is suggested that a realistic defense by the psychology profession should include at least two major elements at the beginning. First of all, it is argued that Gross has not revealed anything about test validity which is not common knowledge to any professionally trained psychologist. Second, it should be clearly emphasized that much of the writer's comments pertain to a certain segment of the psychological profession, and that many of his observations have been made on self-appointed testers with no professional status or recognition of any sort. Further, it should be added that we in the profession are much concerned about the unethical and haphazard uses of tests and the unsubstantiated claims of pseudopsychologists, and that we have ethics committees in the American Psychological Association and in most states which are endeavoring to protect the public through certification procedures and public education. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Testing the feasibility of DNA typing for human identification by PCR and an oligonucleotide ligation assay

The use of DNA typing in human genome analysis is increasing and finding widespread application in the area of forensic and paternity testing. In this report, we explore the feasibility of typing single nucleotide polymorphisms (SNPs) by using a semiautomated method for analyzing human DNA samples. In this approach, PCR is used to amplify segments of human DNA containing a common SNP. Allelic nucleotides in the amplified product are then typed by a colorimetric implementation of the oligonucleotide ligation assay (OLA). The results of the combined assay, PCR/OLA, are read directly by a spectrophotometer; the absorbances are compiled; and the genotypes are automatically determined. A panel of 20 markers has been developed for DNA typing and has been tested using a sample panel from the CEPH pedigrees (CEPH parents). The results of this typing, as well as the potential to apply this method to larger populations, are discussed.     

Multi-continuum analysis of thermally induced matrix cracking

Matrix micro-cracking due to thermal loading is a major concern in composite cryogenic tanks because it presents permeation paths for the stored fluids and gases. Accurate prediction of composite damage due to micro-crack initiation is thus an important aspect of tank analysis and design. In the research presented, failure criteria are applied at both the composite (macro-) and constituent (micro-) scale in an effort to assess the most effective analysis techniques for predicting composite damage. Constituent scale information is developed using multi-continuum theory, a classic strain decomposition approach. Numerical predictions are correlated against experimental results.     

Distinct mechanisms for the induction and maintenance of allograft tolerance with CTLA4-Fc treatment

A murine CTLA4/Fc gamma2a heavy chain (mCTLA4-Fc) chimeric fusion molecule was used in B6AF1 recipients of BALB/c pancreatic islet allografts to study the induction and maintenance of tolerance following inhibition of the CD28-B7 pathway for T cell activation. Donor-specific tolerance was achieved by administering 100 microg of mCTLA4-Fc on alternate days for 14 days (8 total doses) or a single 500 microg dose of mCTLA4-Fc on day 2 after transplant. Tolerance was mediated by long-lived peripheral lymphocytes and showed features of organ and alloantigen specificity. Whereas tolerance could not be established in allograft recipients receiving simultaneous mCTLA4-Fc and rIL-2, previously tolerant animals did not reject their grafts when given IL-2, suggesting that the induction and maintenance phases of tolerance were distinct and separate. The maintenance of donor-specific tolerance was an active immunologic process that was CD4+ T cell dependent and could be adoptively transferred to naive lymphocytes, but could not be explained by apoptosis or deletion of alloreactive T cells. Although an IL-2-sensitive mechanism such as anergy may contribute toward the induction of tolerance, its maintenance involves active suppression.