Equation of State of CO_{2} Shock Compressed to 1 TPa.

Equation-of-state (pressure, density, temperature, internal energy) and reflectivity measurements on shock-compressed CO_{2} at and above the insulating-to-conducting transition reveal new insight into the chemistry of simple molecular systems in the warm-dense-matter regime. CO_{2} samples were precompressed in diamond-anvil cells to tune the initial densities from 1.35 g/cm^{3} (liquid) to 1.74 g/cm^{3} (solid) at room temperature and were then shock compressed up to 1 TPa and 93 000 K. Variation in initial density was leveraged to infer thermodynamic derivatives including specific heat and Gruneisen coefficient, exposing a complex bonded and moderately ionized state at the most extreme conditions studied.

3T MRI Whole-Brain Microscopy Discrimination of Subcortical Anatomy, Part 2: Basal Forebrain.

BACKGROUND AND PURPOSE: The basal forebrain contains multiple structures of great interest to emerging functional neurosurgery applications, yet many neuroradiologists are unfamiliar with this neuroanatomy because it is not resolved with current clinical MR imaging. MATERIALS AND METHODS: We applied an optimized TSE T2 sequence to washed whole postmortem brain samples (n = 13) to demonstrate and characterize the detailed anatomy of the basal forebrain using a clinical 3T MR imaging scanner. We measured the size of selected internal myelinated pathways and measured subthalamic nucleus size, oblique orientation, and position relative to the intercommissural point. RESULTS: We identified most basal ganglia and diencephalon structures using serial axial, coronal, and sagittal planes relative to the intercommissural plane. Specific oblique image orientations demonstrated the positions and anatomic relationships for selected structures of interest to functional neurosurgery. We observed only 0.2- to 0.3-mm right-left differences in the anteroposterior and superoinferior length of the subthalamic nucleus (P = .084 and .047, respectively). Individual variability for the subthalamic nucleus was greatest for angulation within the sagittal plane (range, 15°-37°), transverse dimension (range, 2-6.7 mm), and most inferior border (range, 4-7 mm below the intercommissural plane). CONCLUSIONS: Direct identification of basal forebrain structures in multiple planes using the TSE T2 sequence makes this challenging neuroanatomy more accessible to practicing neuroradiologists. This protocol can be used to better define individual variations relevant to functional neurosurgical targeting and validate/complement advanced MR imaging methods being developed for direct visualization of these structures in living patients.

3T MRI Whole-Brain Microscopy Discrimination of Subcortical Anatomy, Part 1: Brain Stem.

BACKGROUND AND PURPOSE: The brain stem is compactly organized with life-sustaining sensorimotor and autonomic structures that can be affected by numerous pathologies but can be difficult to resolve on conventional MR imaging. MATERIALS AND METHODS: We applied an optimized TSE T2 sequence to washed postmortem brain samples to reveal exquisite and reproducible brain stem anatomic MR imaging contrast comparable with histologic atlases. This resource-efficient approach can be performed across multiple whole-brain samples with relatively short acquisition times (2 hours per imaging plane) using clinical 3T MR imaging systems. RESULTS: We identified most brain stem structures at 7 canonical axial levels. Multiplanar or oblique planes illustrate the 3D course and spatial relationships of major brain stem white matter pathways. Measurements of the relative position, course, and cross-sectional area of these pathways across multiple samples allow estimation of pathway location in other samples or clinical subjects. Possible structure-function asymmetries in these pathways will require further study-that is, the cross-sectional area of the left corticospinal tract in the midpons appeared 20% larger (n = 13 brains, P < .10). CONCLUSIONS: Compared with traditional atlases, multiplanar MR imaging contrast has advantages for learning and retaining brain stem anatomy for clinicians and trainees. Direct TSE MR imaging sequence discrimination of brain stem anatomy can help validate other MR imaging contrasts, such as diffusion tractography, or serve as a structural template for extracting quantitative MR imaging data in future postmortem investigations.

Hydrazine-mediated strongly coupled Re(CO)3 dimers.

Dimeric metal complexes can often exhibit coupling interactions via bridging ligands. In this report, we present two Re(CO)3 dimers, where the metals are linked via a bis(pyca) hydrazine (pyca = pyridine-2-carbaldehyde imine) Schiff base ligand. For the dimeric compounds 4 and 5, we observe strong coupling across the dimer as measured by cyclic voltammetry: ∼480 mV separations between the first and the second reduction waves that correspond to comproportionation constants close to 1.5 × 10(8). Evidence for a mixed valence state upon one electron reduction was also observed by spectroelectrochemistry in which a clear inter-valence charge-transfer (IVCT) band was observed in [4]- and [5]-complexes. The electronic structures of all target compounds were probed by DFT and TDDFT computational methods. DFT calculations indicate that reduction takes place at the diimine units, and that the observed coupling is a ligand-based phenomenon, rather than one that involves metal-based orbitals.

Ultrafast dynamics of a new class of highly fluorescent boron difluoride dyes.

The first ultrafast study of the dimeric fluorescent BF2 dye BOPHY is presented. When compared to a structurally related BODIPY dye, similar photophysical dynamics are observed, including an intermediate kinetic component present in both dye types.

Sickle cell screening policies as portent: how will the human genome project affect public sector genetic services?

The Human Genome Project holds much promise for providing dramatic improvements in our understanding of and means to diagnose and treat many diseases. As this enormously important endeavor proceeds, research on ethical, legal, and social implications of this new science is being conducted to forecast problems and recommend policy option solutions to avoid what might otherwise become adverse consequences. Sickle cell screening is an example of a technology that was introduced in a manner that raised poignant issues. On the basis of sickle cell issues, we examined policy issues likely to occur as new genetic technologies are incorporated into medical practice. Discussion and development of a national consensus on the appropriate content and just delivery of public sector genetic services is vital; otherwise, the impact of Human Genome Project-derived technology may result in misadventures that amplify problems currently evident in newborn screening programs. New DNA-based diagnostic technologies and therapies will soon enter the stream of commerce. The recommendations offered here, while based on examination of sickle cell disease policies, are intended to address both current inequities as well as potential future issues related to stigmatization and distributive justice.

Roles of physicians, genetic counselors, and nurses in the genetic counseling process.

A self-administered questionnaire was mailed to 325 genetic counseling professionals in the southeastern United States and 204 (63%) completed it. Among those responding, 32% held master's degrees in genetic counseling, 30% M.D. degrees, 23% degrees in nursing, and 3% master's degrees in social work. While genetic counseling typically involves team effort, members were generally unclear regarding their roles in the process. Respondents rarely referred their clients to social workers but believe they should. Most did not believe that master's trained genetic counselors should be the only health professional who provide counseling. The respondents strongly supported goals that dealt with the educative aspect of counseling and protection of patient autonomy.

Malignant gastroesophageal polyp: a case report.

This case illustrates the entity of esophagealadenocarcinoma presenting in an esophageal polyp. Esophageal polyps are rare. The clinical presentation, diagnostic evaluation, pathophysiology, and treatment are discussed.

Professional preparation of individuals who provide genetic counseling services.

An unprecedented increase has occurred in demand for genetic counseling services during the current decade. This study examined the complex issue of who currently provides genetic counseling services and the professional preparation of these personnel. A self-administered questionnaire was mailed to 325 genetic counseling professionals in the southeastern United States who were members of the Southeast Regional Genetics Group (SERGG), National Society of Genetic Counselors, or American Society of Human Genetics States; 204 completed the questionnaire (63%). Seventy percent of respondents were female and 30% were male. Thirty percent of respondents held MD degrees; nine physicians held PhD degrees. Most physicians were male. Thirty-two percent of respondents held master's degrees in genetic counseling; five counselors held PhD degrees. Twenty-three percent of respondents were nurses; eight nurses held master's degrees. Three percent of respondents were social workers. Individuals with other degrees, such as an associate of science in medical technology and a doctoral degree in education, also provided genetic counseling. Genetic counseling typically involved a team effort, consisting mainly of physicians and genetic counselors. Most respondents reported college coursework in human genetics, supervised training, and seminar/workshop training. Thirty percent reported college coursework in counseling techniques, supervised training, and seminar/workshop training. Policy recommendations are offered concerning professional preparation of genetic counselors.

Expanding rural primary care training by employing information technologies: the need for participation by medical reference librarians.

The use of rural sites to train badly needed primary care providers requires access to sophisticated medical information not traditionally available outside of academic health centers. Medical reference librarians can play a key role in the development of primary care training sites in rural settings. Electronic information technologies, with proactive support from medical reference librarians, can provide current and detailed information without concern for distance from the health science center library. This paper discusses recent developments in technology, describes current challenges to the application of this technology in rural settings, and provides policy recommendations for medical reference librarians to enhance rural primary care training.

Impact of new information technologies on training and continuing education for rural health professionals.

Recently developed and emerging information and communications technologies offer the potential to move the clinical training of physicians and other health professionals away from the resource intensive urban academic health center, with its emphasis on tertiary care, and into rural settings that may be better able to place emphasis on the production of badly needed primary care providers. These same technologies also offer myriad opportunities to enhance the continuing education of health professionals in rural settings. This article explores the effect of new technologies for rural tele-education by briefly reviewing the effect of technology on health professionals' education, describing ongoing applications of tele-education, and discussing the likely effect of new technological developments on the future of tele-education. Tele-education has tremendous potential for improving the health care of rural Americans, and policy-makers must direct resources to its priority development in rural communities.

Older Floridians' attitudes toward and use of dental care.

Older Floridians (mean age 78 years) were interviewed regarding their use of dental care, attitudes toward dental care, and other characteristics hypothesized as being explanatory of dental care use. Fifty-two percent of respondents reported having been to a dentist within the past year, and 31% had not been within the previous 5 years. Five constructs measured attitudes toward dental care and dental health: (a) the importance placed on regular dental care and oral hygiene, (b) the importance of avoiding tobacco to prevent oral cancer, (c) the value of dental care, (d) negative aspects of dental care, and (e) satisfaction with the last dental visit. In a multivariate model, the value of dental care and importance of regular care and oral hygiene wer significantly correlated with dental care use. These findings are consistent with the conclusion that attitudes contribute to understanding dental care use in later life, a contribution that is independent of the direct effects of socioeconomic status and dentate status.

Attitudinal and behavioral characteristics of older Floridians with tooth loss.

In this cross-sectional study of Floridians aged 65 yr or older, 600 persons were interviewed to identify the characteristics of individuals who survived into old age with an intact or nearly intact dentition. Persons with total or partial tooth loss reported less frequent dental care, less ability to pay dental care fees, less frequent dental hygiene, and were more likely to have been smokers or diabetic. Persons with tooth loss also had less positive attitudes toward dentists and dental care. These cross-sectional findings are consistent with tooth loss being the result of disease-, behavior-, and attitude-related causes, and/or their interactions. Tobacco use, diabetes, and infrequent oral hygiene and dental care may increase risk for dental disease; decreased ability to pay for dental treatment may impair utilization of non-extraction treatment options, and negative attitudes toward dental treatment may influence the desire for non-extraction treatment options. Research targeted toward modifying attitudes toward dental treatment may be useful in preventing or delaying tooth loss, and measurement of attitudes may be a useful way to identify individuals at the greatest risk for tooth loss for intervention studies.

Ethical and practical implications of the human genome initiative for family medicine.

Major advances in predictive genetic testing resulting from the Human Genome Initiative could change significantly the routine practice of family medicine. Family physicians should be aware that increased genetic information may affect patients' abilities to acquire and maintain insurance and employment and that interested parties will have incentives to seek this information. The social consequences of genetic information, as well as increased health promotion efforts, may raise problems of informed consent and confidentiality. In addition to their ethical implications, these developments will also affect the practice of family physicians in practical ways such as record keeping. We discuss cases that illustrate the potential impact of these emerging technologies on the practice of family medicine.

Insurance and genetic testing: where are we now?

Basic research will spur development of genetic tests that are capable of presymptomatic prediction of disease, disability, and premature death in presently asymptomatic individuals. Concerns have been expressed about potential harms related to the use of genetic test results, especially loss of confidentiality, eugenics, and discrimination. Existing laws and administrative policies may not be sufficient to assure that genetic information is used fairly. To provide factual information and conceptual principles upon which sound social policy can be based, the Human Genome Initiative established an Ethical, Legal, and Social Issues Program. Among the first areas to be identified as a priority for study was insurance. This paper provides a review of life, health, and disability insurance systems, including basic principles, risk classification, and market and regulatory issues, and examines the potential impact of genetic information on the insurance industry.

Recruitment and retention of rural physicians: issues for the 1990s.

This paper briefly describes a number of structural and economic changes in the profession of medicine and in the rural medical care delivery system that have occurred since about 1970. Changes in the national physician supply; in the training, work, and practice characteristics of physicians; in the demographic characteristics of physicians; in the medical resources available in rural communities; and in federal and state support for the provision of medical services are noted. Four conceptual models that underlie physician recruitment and retention programs for small towns and rural communities are described. These include affinity models, which attempt to recruit rural persons into training or foster interest in rural practice among trainees; economic incentive models, which address reimbursement or payment mechanisms to increase economic rewards for rural practice; practice characteristics models, which address technical, collegial, referral, and other structural barriers to rural practice; and indenture models, which recruit temporary providers in exchange for scholarship support, loan forgiveness, or licensure. Examples of applications of each model are provided and the effects of changes in the medical care system on the effectiveness of each model are assessed. Finally, it is argued that elements of an optimal model for the recruitment of physicians to rural practice include the promotion of medical careers among rural high school students, the provision of financial and cultural support for their training, the development of technical and collegial support systems, and the limited use of indenture mechanisms to meet the needs of the most impoverished or isolated rural settings.

Impact of a required family medicine clerkship on medical students' attitudes about primary care.

A study of 314 medical students before and after a required third-year clerkship in family medicine explored relationships among exposure to the clerkship and changes in attitudes toward primary care. The survey instrument contained 29 statements distinguishing the philosophy of primary care from that of subspecialty-oriented medicine and asked students' to state their future residency plans. The responses of the primary care and subspecialty-oriented groups were the most disparate, whereas the students who were uncertain about residency plans shifted on several items from an alignment with the specialty group toward an alignment with the primary care group. This study shows that experience in a family medicine clerkship may be associated with changes in attitudes that represent development of a more informed image of primary care.