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The evolution of modern eukaryotic phytoplankton.

The community structure and ecological function of contemporary marine ecosystems are critically dependent on eukaryotic phytoplankton. Although numerically inferior to cyanobacteria, these organisms are responsible for the majority of the flux of organic matter to higher trophic levels and the ocean interior. Photosynthetic eukaryotes evolved more than 1.5 billion years ago in the Proterozoic oceans. However, it was not until the Mesozoic Era (251 to 65 million years ago) that the three principal phytoplankton clades that would come to dominate the modern seas rose to ecological prominence. In contrast to their pioneering predecessors, the dinoflagellates, coccolithophores, and diatoms all contain plastids derived from an ancestral red alga by secondary symbiosis. Here we examine the geological, geochemical, and biological processes that contributed to the rise of these three, distantly related, phytoplankton groups.

Biodiversity↗

The late Miocene radiation of modern Felidae: a genetic assessment.

Modern felid species descend from relatively recent (<11 million years ago) divergence and speciation events that produced successful predatory carnivores worldwide but that have confounded taxonomic classifications. A highly resolved molecular phylogeny with divergence dates for all living cat species, derived from autosomal, X-linked, Y-linked, and mitochondrial gene segments (22,789 base pairs) and 16 fossil calibrations define eight principal lineages produced through at least 10 intercontinental migrations facilitated by sea-level fluctuations. A ghost lineage analysis indicates that available felid fossils underestimate (i.e., unrepresented basal branch length) first occurrence by an average of 76%, revealing a low representation of felid lineages in paleontological remains. The phylogenetic performance of distinct gene classes showed that Y-chromosome segments are appreciably more informative than mitochondrial DNA, X-linked, or autosomal genes in resolving the rapid Felidae species radiation.

Africa↗

A nearly modern amphibious bird from the Early Cretaceous of northwestern China.

Three-dimensional specimens of the volant fossil bird Gansus yumenensis from the Early Cretaceous Xiagou Formation of northwestern China demonstrate that this taxon possesses advanced anatomical features previously known only in Late Cretaceous and Cenozoic ornithuran birds. Phylogenetic analysis recovers Gansus within the Ornithurae, making it the oldest known member of the clade. The Xiagou Formation preserves the oldest known ornithuromorph-dominated avian assemblage. The anatomy of Gansus, like that of other non-neornithean (nonmodern) ornithuran birds, indicates specialization for an amphibious life-style, supporting the hypothesis that modern birds originated in aquatic or littoral niches.

Animals↗

Late Pleistocene human skull from Hofmeyr, South Africa, and modern human origins.

The lack of Late Pleistocene human fossils from sub-Saharan Africa has limited paleontological testing of competing models of recent human evolution. We have dated a skull from Hofmeyr, South Africa, to 36.2 +/- 3.3 thousand years ago through a combination of optically stimulated luminescence and uranium-series dating methods. The skull is morphologically modern overall but displays some archaic features. Its strongest morphometric affinities are with Upper Paleolithic (UP) Eurasians rather than recent, geographically proximate people. The Hofmeyr cranium is consistent with the hypothesis that UP Eurasians descended from a population that emigrated from sub-Saharan Africa in the Late Pleistocene.

Africa South of the Sahara↗

Uric acid, uric acid dihydrate, and urates in urinary calculi, ancient and modern.

Uric acid, uric acid dihydrate, and ammnoniumn acid urate occur in bladder stones both ancient and modern. They are seldomn abuindant in stones fromn technically developed areas. Urates are usually confined to children's endemic bladder stones; uric acid dihydrate is rare, but uric acid used to be commzinon in bladder stones from elderly men.

Adolescent↗

The spread of Western science. A three-stage model describes the introduction of modern science into any non-European nation.

There is no need to summarize the features of this simplified model, which describes the manner in which modern science was transmitted to the lands beyond Western Europe. The graph of Fig. 1 and the examples drawn from science in various lands should have made them clear. It may be in order, however, to reiterate that there is nothing about the phases of my model that is cosmically or metaphysically necessary. I am satisfied if my attempt will interest others to go beyond my crude analysis and make a systematic investigation of the diffusion of Western science throughout the world. Such an investigation would include a comparative appraisal of the development of science in different national, cultural, and social settings and would mark the beginnings of truly comparative studies in the history and sociology of science. The present lack of comparative studies in these disciplines can be attributed to the widespread belief that science is strictly an international endeavor. In one sense this is true. As Sir Isaac Newton remarked in his Principia (49), "the descent of stones in Europe and in America" must both be explained by one set of physical laws. Yet, we cannot ignore the peculiar environment in which members of a national group of scientists are trained and carry on their research. While I do not hold with the Nazi theorists that science is a direct reflection of the racial or national spirit (50), neither do I accept Chekhov's dictum (51) that "there is no national science just as there is no national multiplication table. . . ." In emphasizing the international nature of scientific inquiry we have forgotten that science exists in a local social setting. If that setting does not decisively mold the conceptual growth of science, it can at least affect the number and types of individuals who are free to participate in the internal development of science. Perhaps the effect is more profound; only future scholarship can determine the depth of its influence.

Acculturation↗

Institutions in modern society: caretakers and subjects.

The problems that relate to the outermost limits of institutional care, if such limits exist, will certainly be among the most salient problems during the coming years-no matter whether such care proceeds on an inpatient or an outpatient basis. Whatever course may be taken will certainly affect the lives of every citizen in urbanized and industrialized society. At present in California there is considerable shifting of individuals from one care status or category to another, in efforts to find accommodations that will better reflect the realities of modern existence. However, such shifting of caseloads as the moving of individuals from nursing and convalescent homes to hospitals and back again does not constitute a change, either from the standpoint of the subjects involved or from the standpoint of significantly affecting the overall caseload. Most commonly, the shifting of caseloads has been merely jurisdictional. Much the same can be said of the transfers from a police agency to welfare, or vice versa. Similarly, a shift from inpatient status to outpatient status does not constitute a significant change. Such transfers from one jurisdiction to another reflect a reduction in caseload for one agency, but a corresponding increase in caseload for another. Thus, there has been no significant change in the subject population as such. Jurisdictional transfers are often merely caretaking actions that reflect bureaucratic decisions. Equally often, such decisions do not address themselves to the basic priorities that guide the functions of caretaking. Explicitly stated priorities must supersede jurisditional transfers if the concept of caretaking is to include better resources for human development and if the subject population is to participate in the managing of institutions. On any given day during 1969 in the state of California, virtually 8 million people from an estimated population of 19,800,000 were under some form of institutional care or in some institutional program, or were employed to provide the care and administer the programs. Clearly this is a vast effort toward the training and retraining, as well as the rehabilitation of people, in the traditional sense of these words. The salient problems that have emerged from this context of urban and industrial development involve social control, social mobility, organizational behavior by caretakers and subjects, minority peoples, and the extensions of institutions into communities. Given these developments, is it not proper to ask whether or not the nature of urbanized and industrialized society has changed to such a point that a return to the past (and past solutions) is no longer feasible? Is it not also proper to ask what voice the subject population will have in helping to guide the urban and industrialized state into the future? And certainly there is a question that virtually everyone will ask: What percentage of tax revenues (whether shared or under direct programs) shall be destined to better meet the problems of this future society, which, it seems, is already upon us?

California↗

Bacterial contamination of drinking water supplies in a modern rural neighborhood.

On six occasions during a 15-month period, the private well and spring water supplies in a modern rural neighborhood of 78 households were examined for total coliforms, fecal coliforms, Staphylococcus aureus, and standard plate count bacteria. More than one-third of the water supplies were unsatisfactory on at least one occasion as judged by standard plate counts over 10(3)/ml and the presence of coliforms, fecal coliforms, and/or S. aureus. Citrobacter freundii, Klebsiella pneumoniae, and Escherichia coli were the most frequently isolated total coliforms. At least 12 other genera of bacteria were identified from standard plate count agar. Coliform contamination was found to be higher after periods of rainfall, and high standard plate counts were more prevalent during warmer weather. These observations probably reflect leakage of surface water into improperly sealed wells or aquifer contamination during winter and the lack of chlorination to control microbial regrowth during the warm season. An inverse correlation was found between the presence of high standard plate counts and incidence of coliforms. Consumer education and at least a twice yearly monitoring of private water supplies (winter and summer) are suggested methods to signal that treatment may be necessary to reduce the risk of waterborne disease.

Bacteria↗

Head injury and limb fracture in modern playgrounds.

There were no serious head injuries in modern Cardiff municipal playgrounds with safety surfaces over five years injury surveillance. The literature suggests serious head injuries did occur before the introduction of safety surfaces.

Accident Prevention↗

Role of modern radiological investigations in obstructive uropathy.

Obstructive uropathy in its various forms accounts for much of the work load in urological units and general hospitals. Until recently, laboratory tests and excretion urography were the only procedures available for its assessment. The past few years have seen the development and refinement of ultrasound, examination by computer tomography, nuclear medicine, antegrade pyelography, and perfusion pressure flow studies. This paper examines the particular qualities of these modern procedures and their role in the clinical assessment of the obstructed urinary tract.

Humans↗

Effect of modern analgesic drugs (tramadol, pentazocine, and buprenorphine) on the bile duct sphincter in man.

Modern narcotic analgesic drugs, such as tramadol, pentazocine, and buprenorphine share similarities of molecular structure with morphine which is widely believed to cause spasm of the bile duct sphincter and so impede bile flow. This study assessed the effects of intravenously administered analgesics on bile duct sphincter motor activity measured by ERCP manometry. Ten minutes after pentazocine injection the duration of contractions and baseline pressure of the bile duct sphincter rose from 6.2 +/- 0.2 to 8.2 +/- 0.27 s and from 5.1 +/- 0.6 to 8.8 +/- 0.4 mmHg respectively. Tramadol, buprenorphine and saline showed no such effect. These data indicated that the effects of such drugs on bile duct sphincter function can be safely assessed by ERCP manometry and that pentazocine adversely affects the bile duct sphincter, whilst tramadol and buprenorphine do not. We consider therefore that pentazocine is not the premedication of first choice for endoscopic procedures involving the sphincter of Oddi and should also be avoided in patients with pancreatic and biliary disorders.

Adult↗

Modern atrial and ventricular leads for permanent cardiac pacing.

Three hundred and fifteen transvenous pacing leads of various modern designs have been assessed over a period of three years. Of these, 103 were implanted in the atrium and 212 in the ventricle. Screw-in leads in the right atrial appendage and short tined leads in the ventricle have resulted in the virtual elimination of lead displacement, and a very low incidence of other lead related problems. In two lead systems it has been found advantageous to have both leads constructed of urethane.

Electrodes, Implanted↗

Cost efficiency analysis of modern cytocentrifugation methods versus liquid based (Cytyc Thinprep) processing of urinary samples.

BACKGROUND/AIMS: Liquid based cytology (LBC) was developed as a replacement for cytocentrifugation in the treatment of cell suspensions. Because accurate data comparing the quality and total cost of modern cytocentrifugation methods versus LBC in non-gynaecological samples are not available, this study was designed to investigate these issues. METHODS: The study comprised 224 urine samples treated with the Thermo Shandon Cytospin 4 using reusable TPX chambers, disposable Cytofunnels for samples up to 0.5 ml, and disposable Megafunnels for samples up to 6 ml. Each method was compared with the Cytyc Thinprep processing of a paired sample. Quality was assessed by scoring cellularity, fixation, red blood cells, leucocytes, abnormalities of urothelial cells, and suitability for molecular studies. Wage costs, investment, and consumables allowed a "total cost" to be calculated on the basis of 200 specimens/month. Total cost and quality combined were used to calculate an index of total quality (ITQ). RESULTS: Cytocentrifugation with disposable chambers resulted in a global quality superior to that of Cytyc Thinprep LBC. Preparation and screening times were 2.25 and 1.33-2 times greater when using LBC compared with cytocentrifugation. The total cost each month reached 1960.23 $ to 2833.43 $ for cytocentrifugation methods and 5464.95 $ for Cytyc Thinprep LBC (92.8-178.8% increased cost). ITQ of cytocentrifugation with disposable chambers surpassed that of Cytyc Thinprep LBC (37.25/32.08 and 9.98, respectively). CONCLUSION: Cytyc Thinprep LBC and cytocentrifugation are both appropriate methods for cytology based molecular studies, but cytocentrifugation remains the quality standard for current treatment of urinary samples because of its lower cost.

Centrifugation↗

Students' attitudes and potential behaviour to a competent patient's request for withdrawal of treatment as they pass through a modern medical curriculum.

OBJECTIVE: To examine students' attitudes and potential behaviour to a competent patient's request for withdrawal of treatment as they pass through a modern medical curriculum. DESIGN: Cohort design. SETTING: University of Glasgow Medical School, United Kingdom. SUBJECTS: A cohort of students entering Glasgow University's new learner centred, integrated medical curriculum in October 1996. METHODS: Students' responses before and after year 1, after year 3, and after year 5 to the assisted suicide vignette of the Ethics in Health Care Survey instrument, were examined quantitatively and qualitatively. Analysis of students' multichoice answers enabled measurement of the movement towards professional consensus opinion. Analysis of written justifications helped determine whether their reasoning was consistent with professional consensus and enabled measurement of change in knowledge content and recognition of the values inherent in the vignette. Themes on students' reasoning behind their decision to withdraw treatment or not were also identified. RESULTS: Students' answers were found to be consistent with professional consensus opinion precurriculum and remained so throughout the curriculum. There was an improvement in the knowledge content of the written responses following the first year of the curriculum, which was sustained postcurriculum. However, students were found to analyse the section mainly in terms of autonomy, with few responses considering the other main ethical principles or the wider ethical perspective. Students were unclear on their legal responsibilities. CONCLUSIONS: Students should be encouraged to consider all relevant ethical principles and the wider ethical perspective when deliberating ethical dilemmas. Students should have a clear understanding of their legal responsibilities.

Adult↗

Sex and the surgery: students' attitudes and potential behaviour as they pass through a modern medical curriculum.

OBJECTIVE: To examine students' attitudes and potential behaviour to a possible intimate relationship with a patient as they pass through a modern medical curriculum. DESIGN: A cohort study of students entering Glasgow University's new learner centred, integrated medical curriculum in October 1996. METHODS: Students' pre year 1 and post year 1, post year 3, and post year 5 responses to the "attractive patient" vignette of the Ethics in Health Care Survey instrument were examined quantitatively and qualitatively. Analysis of students' multi-choice answers enabled measurement of the movement towards professional consensus opinion. Analysis of written justifications helped determine whether their reasoning was consistent with professional consensus and enabled measurement of change in knowledge content and recognition of the values inherent in the vignette. Themes on students' reasoning behind their decision to enter a relationship or not were also identified. RESULTS: No significant movement towards consensus was found at any point in the curriculum. There was little improvement in students' performance in terms of knowledge content and their abilities to recognise the values inherent in the vignette. In deciding to enter a relationship with the patient the most frequently used reasoning was that it could be justified if the patient changed their doctor. CONCLUSIONS: Teaching on the subject of sexual or improper relationships between doctors and patients, including relationships with former patients requires to be made explicit. Case based teaching would fit in with the ethos of the problem based, integrated medical curriculum.

Adult↗

Educational outcomes and leadership to meet the needs of modern health care.

If professionals are to be equipped better to meet the needs of modern health care systems and the standards of practice required, significant educational change is still required. Educational change requires leadership, and lack of educational leadership may have impeded change in the past. In practical terms standards refer to outcomes, and thus an outcome based approach to clinical education is advocated as the one most likely to provide an appropriate framework for organisational and system change. The provision of explicit statements of learning intent, an educational process enabling acquisition and demonstration of these, and criteria for ensuring their achievement are the key features of such a framework. The derivation of an appropriate outcome set should emphasise what the learners will be able to do following the learning experience, how they will subsequently approach these tasks, and what, as a professional, they will bring to their practice. Once defined, the learning outcomes should determine, in turn, the nature of the learning experience enabling their achievement and the assessment processes to certify that they have been met. Provision of the necessary educational environment requires an understanding of the close interrelationship between learning style, learning theory, and methods whereby active and deep learning may be fostered. If desired change is to prevail, a conducive educational culture which values learning as well as evaluation, review, and enhancement must be engendered. It is the responsibility of all who teach to foster such an environment and culture, for all practitioners involved in health care have a leadership role in education.

Adult↗

Comparative bacterial drug resistance in modern battery and free-range poultry in a tropical environment.

A correlation between the use of antibiotics and drug resistance was found among Escherichia coli strains isolated from modern battery poultry at the University of Ibadan, Nigeria. All 1248 E coli strains from university poultry and 2196 strains from a commercial poultry farm in Ibadan were resistant to tetracycline, streptomycin and sulphonamide, the minimal inhibitory concentrations of these drugs being found to be several times those of the control E coli NCTC 10418. In contrast, all 2284 strains isolated from free-range town and village poultry were sensitive to these drugs. In the tropical developing countries with poor environmental sanitation and low personal hygiene, this situation has public health implications.

Animal Feed↗