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At least 109 records · Page 6Linked to original sources
PubMed2005

Processing of conflicting cues in an attention-shift paradigm studied with fMRI.

We investigated the effects of conflicting cues in visual attention on brain function, based on a modified version of the Posner cue-target paradigm. The classic paradigm utilizes either a peripheral or centrally placed cue that involuntary or voluntary results in a shift of attention to the cued side. The modified paradigm involves presenting both a peripheral and central cue at the same time, but where the two cues convey conflicting information regarding direction of attention. Functional magnetic resonance imaging (fMRI) were used to record neuronal activation in localized brain areas and networks when the subjects performed the attention task. We hypothesized that the 'exogenous invalid/endogenous valid' condition would activate the anterior attention system to a larger extent than the 'exogenous valid/endogenous invalid' condition, reflecting a need for top-down information processing in this condition. The results for performance data showed that the peripheral cue took precedence over the centrally placed cue when the two cues were in conflict, since reaction times were significantly longer in the "exogenous invalid/endogenous valid" condition. The fMRI data showed an increase in activation in the visual cortex, the left parietal lobule, and in the left cingulate gyrus in both the exogenous valid/endogenous invalid and exogenous invalid/endogenous valid conditions. For the exogenous invalid/endogenous valid condition, there were, in addition, significant activations also in the inferior and middle frontal gyri, and in the precentral gyrus. We interpret these findings as reflecting that these brain areas particularly involved in top-down modulation of attention that interferes with a bottom-up, exogenous-driven effect.

Adult↗
PubMed2006

Cellular senescence, cancer, and organismal aging: a paradigm shift.

Cellular senescence is an anti-cancer mechanism and may contribute to organismal aging. A change in paradigm has been proposed that cellular senescence may reduce cancer mortality rather than promote it late in life, and thus positively contributes to longevity in organisms with renewable tissues as a common mechanism across the species.

Aging↗
PubMed2003

Monitoring right ventricular volumes: a paradigm shift.

The resuscitation of critically ill patients frequently requires the administration of fluids for the purpose of increasing cardiac output and oxygen delivery to the tissues. The assessment of the patient's preload status during this process is vital. Traditionally, preload assessment has been through the use of right atrial pressure and pulmonary artery occlusion pressure, which are often referred to as the "filling pressures." The use of these filling pressures is based upon the assumption that ventricular compliance does not change. In recent years studies have demonstrated a poor correlation between these pressures and cardiac output. More recently, the ability to measure right ventricular end-diastolic volume (RVEDV) at the bedside using a modified pulmonary artery catheter became available. Initially the measurement was obtained using intermittent bolus measurements. Today, near continuous measurements of RVEDV are available. The shift from using pressure measurements for the purpose of assessing preload to the new paradigm of using right ventricular volumetric measurements is challenging. The purpose of this article is to review pertinent anatomy of the right ventricle and the interdependence of the ventricular chambers. The volumetric parameters are presented followed by a discussion of research supporting the use of the volumetric parameters in lieu of pressure measurements for preload assessment in a variety of patient populations. The technology providing continuous RVEDV measurements is presented followed by a discussion of a case study demonstrating the value of continuous measurements. Specific implications for the advanced practice nurse are addressed.

Cardiac Output↗
PubMed1999

The pleasure of the bottomless: postmodernism, chaos and paradigm shifts.

In her paper Reconstructing Nursing: Evidence, Artistry and the Curriculum, Marks-Maran (1999) attempted to outline a new postmodern paradigm for nursing. Whilst I fully support this timely discussion of new insights into nursing theory and practice, Marks-Maran unfortunately presents a very idiosyncratic version of postmodernism which is both simplistic and, at times; inaccurate. My main concern, however, is with her assertion that postmodernism offers a new paradigm for nursing, since she misses the fundamental point that postmodernism is not a critique or replacement for the modernist paradigm, but a challenge to the very notion of paradigms. Rather than attempting to replace the modernist paradigm of nursing, then, postmodernism offers what Spivak called 'the pleasure of the bottomless' in which the perceived certainties of science are decentred and the authority by which all knowledge claims are made is questioned.

Humans↗
PubMed1978

Perceptual versus mediational learning in a total change concept-shift paradigm.

The experiment investigated the effects of language acquisition by children in Grades 1 to 4 on performance in a concept-shift task in which the relevant stimulus attributes were either the colour of ink in which a word was written or the meaning of the word. Both English stream and French Immersion children served as subjects. The results indicated a developmental sequence from perceptual learning to verbal mediation. This process was demonstrated at an earlier stage in the French Immersion students who formed a more highly selected group, and intellectual or socio-economic explanations for these differences may be feasible. The relative speed of acquisition of intradimensional and extradimensional shifts interacts with the perceptual/mediational process.

Child↗
PubMed2004

Endoscopic electrosurgical management of posterior epistaxis: shifting paradigm.

Recent literature has embraced the use of electrosurgery, sphenopalatine vascular clipping, and endoscopy in posterior epistaxis. With the advent of endoscopy, the surgical treatment of posterior epistaxis has shifted from internal maxillary ligation to endoscopic sphenopalatine artery control. This article introduces an endoscopic electrosurgical approach for patients suffering from idiopathic posterior epistaxis that combines one or more of the following methods: endoscopic selective branch cauterization, endoscopic sphenopalatine artery cautery, and endoscopic posterior nasal cauterization. This approach is currently used in a hospital-based community otolaryngology practice and is presented from a Canadian health care perspective (Quebec). This article presents the experience in a series of 17 patients treated during a 35-month period and prospectively followed and discusses the surgical technique, patients' outcome, and the implications of such a practice.

Adult↗
PubMed1993

Breast cancer 2000 BC to 2000 AD--time for a paradigm shift?

In this paper I trace the history of the development of the treatment of breast cancer over a 4000-year period. I point out that there have basically been three paradigms within which we have studied and developed treatment for this disease. Clinical trials over the last twenty years as an expression of the scientific method in action, have demonstrated the limited success of the contemporary paradigm with its therapeutic sequelae of breast conserving surgery and adjuvant systemic therapy. At the same time a critical review of the natural history of breast cancer and the results of current treatments suggest logical inconsistencies in the model. I have therefore constructed a novel paradigm which better fits the available information by suggesting that metastases are not only a result of cellular transmission of breast cancer but sub-cellular transmission using the mechanism of in vivo transfection. Although this may sound far fetched, there are a series of remarkable studies in the literature which supports this conceptual revolution. This is surely a fertile field for research and the therapeutic consequences would be obvious. They might suggest that more aggressive adjuvant systemic chemotherapy based on the conventional model is unlikely to achieve any additional benefit, whereas therapy based on anti-viral drugs might produce the next therapeutic advance. It is not the intention of this article to persuade readers that the alternative paradigm is true but merely to open minds to the study of history and scientific philosophy to ensure that we do not repeat the errors of the past.

Breast Neoplasms↗
PubMed2003

[Hand washing. A paradigm shift].

Washing one's hands is one of the principal methods to control infections. At present time, various studies provide evidence that decontaminating one's hands with an alcohol based solution is just as effective, quicker to use and easier. This fact is an important paradigm change in the control over the transmission of infections. The objective of this article is to present and discuss the most relevant aspects of these new recommendations.

Hand Disinfection↗
PubMed1995

Bilingual special education teachers' shifting paradigms: complex responses to educational reform.

This study examined the nature and process of change among five bilingual special education teachers as they attempted to modify existing instructional practices. Three factors affected the change process: (a) The more special education training in the teachers' background, the stronger their reductionist orientation; (b) change involves shifts in instructional practices and shifts in beliefs, and they do not automatically go hand in hand; and (c) change is most facilitated at the beginning stages of collaboration by including practicing members of the teachers' occupational community as agents of change.

Attitude↗
PubMed2004

Two colons-two cancers: paradigm shift and clinical implications.

Embryological and physiological data suggest that proximal (in relation to the splenic flexure) and distal parts of the colon represent distinct anatomical and functional entities. Since 1990, molecular biologists have identified two distinct pathways, microsatellite instability (MSI) and chromosomal instability (CIN), which are involved in the pathogenesis of colon cancer (CC). Thus, a new paradigm has emerged with the discovery that CC is a heterogeneous disease; furthermore recent data have demonstrated that these two distinct pathways in colorectal carcinogenesis are characterized by a different clinical outcome. The implications for the clinicians are twofold; (1) tumors originating from the proximal colon have a better prognosis due to a high percentage of MSI-positive lesions; and (2) location of the neoplasm in reference to the splenic flexure should be documented before group stratification in ongoing trials of adjuvant chemotherapy for CC. In the future, clinical decision-making regarding adjuvant chemotherapy might be stratified according to the MSI status of cancers located proximally to the splenic flexure.

Chemotherapy, Adjuvant↗
PubMedDate not supplied

Biomedicine's electronic publishing paradigm shift: copyright policy and PubMed Central.

Biomedical publishing stands at a crossroads. The traditional print, peer-reviewed, subscription journal has served science well but is now being called into question. Because of spiraling print journal costs and the worldwide acceptance of the Internet as a valid publication medium, there is a compelling opportunity to re-examine our current paradigm and future options. This report illustrates the conflicts and restrictions inherent in the current publishing model and examines how the single act of permitting authors to retain copyright of their scholarly manuscripts may preserve the quality-control function of the current journal system while allowing PubMed Central, the Internet archiving system recently proposed by the director of the National Institutes of Health, to simplify and liberate access to the world's biomedical literature.

Authorship↗
PubMed2006

The pathology of multiple sclerosis: a paradigm shift.

PURPOSE OF REVIEW: Detailed immunopathological assessment of multiple sclerosis tissue remains the research tool most likely to elucidate the major processes involved in disease pathogenesis and tissue injury. Such studies steer and provide the impetus for refining cellular/molecular investigations and developing more relevant disease models in animals. RECENT FINDINGS: Recent observations in early multiple sclerosis lesions challenge the traditional hypothesis that multiple sclerosis arises as the result of a primary autoimmune process that specifically targets myelin antigen(s). A new multiple sclerosis paradigm proposes that oligodendrocyte apoptosis is the earliest change in newly forming lesions and that tissue injury is amplified by the subsequent recruitment of a systemic immune response. Over months to years the pathology of multiple sclerosis is transformed and the changes which accompany the late phase of the disease suggest that the inflammatory response becomes progressively 'compartmentalized' and therefore largely isolated from systemic influence with time. SUMMARY: Recent pathological studies raise important questions regarding the aetiology of oligodendrocyte apoptosis, the mechanisms by which the accompanying inflammatory response amplifies tissue injury and the regulation of central nervous system immunity. An improved understanding of these processes is essential for advancing therapeutic interventions applicable to different stages of the disease.

Animals↗
PubMed1986

The curve-shift paradigm in self-stimulation.

Eleven rats were trained to press a lever in an operant chamber in order to earn rewarding trains of cathodal rectangular pulses of fixed intensity and variable frequency. The rate-frequency functions were examined under administration of two neuroleptics (pimozide and chlorpromazine) and three manipulations that interfered with bar pressing (muscular relaxation with methocarbamol, increased lever weight, and limitation of maximum response rates by an F1 reinforcement schedule). Chlorpromazine, and pimozide at low dosages produced a near parallel shift of the rate-frequency functions on the logarithmic axis of pulses, suggesting that these drugs decreased the reinforcing efficacy of the stimulation. The three conditions that interfered with bar-pressing decreased the asymptotic rates and produced small or moderate lateral shifts. Changes in the reinforcing efficacy of the stimulation following the above manipulations were inferred from the shift in the number of pulses required at zero and half-maximal performance (theta 0 and M50 indices, respectively). In the cases of the manipulations that interfered with bar-pressing, M50 indicated a larger artifactual change in the efficacy of the stimulation, compared to theta 0. This phenomenon was mainly due to the fact that the asymptote of the altered functions was shifted towards higher pulse numbers.

Animals↗
PubMed2005

The coming paradigm shift in forensic identification science.

Converging legal and scientific forces are pushing the traditional forensic identification sciences toward fundamental change. The assumption of discernible uniqueness that resides at the core of these fields is weakened by evidence of errors in proficiency testing and in actual cases. Changes in the law pertaining to the admissibility of expert evidence in court, together with the emergence of DNA typing as a model for a scientifically defensible approach to questions of shared identity, are driving the older forensic sciences toward a new scientific paradigm.

DNA↗
PubMed2006

Revolutions and shifting paradigms in human factors & ergonomics.

The "Revolution in Information Technology" has spawned a series of transformational revolutions in the nature and practice of human factors and ergonomics (HFE). "Generation 1" HFE evolved with a focus on adapting equipment, workplace and tasks to human capabilities and limitations. Generation 2, focused on cognitive systems integration, arose in response to the need to manage automation and dynamic function allocation. Generation 3 is focused on symbiotic technologies that can amplify human physical and cognitive capabilities. Generation 4 is emergent and is focused on biological enhancement of physical or cognitive capabilities. The shift from HFE Generations 1 and 2 to Generations 3 and 4 profoundly alters accepted boundary constraints on the adaptability of humans in complex systems design. Furthermore, it has opened an ethical divide between those that see cognitive and physical enhancement as a great benefit to society and those who perceive this as tampering with the fundamentals of human nature.

Aging↗
PubMed1999

Paradigm shifts: new techniques to answer new questions.

The advent of a multiple-channels approach to spatial vision 20 years ago raised important questions that were difficult to approach empirically, given the technology and analytic tools of the time. These questions concerned the interaction or combination of different components of a stimulus--questions that have recently resurfaced in more complex form. Classical psychophysical methods for assessing whether two stimulus aspects are coded independently (e.g., masking, adaptation, and cue-summation) provide only limited information about the nature of whatever interactions are discovered. In both older work in detection and recent work in complex pattern discrimination, we have used a double-judgment paradigm in which the observer rates two aspects of a stimulus simultaneously. The paradigm provides a rich source of information about the codes underlying each psychophysical decision and which are unique in permitting us to psychophysically investigate effects resulting from neural noise in the system. Our analyses draw on theories of dimensional interaction in signal detection theory and in information theory, and on methods from several branches of statistics, including categorical data analysis and structural equation modeling. We review the theoretical, technological, methodological, and personal influences that led us to develop this approach.

History, 20th Century↗
PubMed1991

Osteopathic research: the needed paradigm shift.

The purposes of this article are twofold: (1) To assist scientists on the faculties of colleges of osteopathic medicine in the design of research projects relevant to osteopathic medical theory and practice; and (2) to assist clinical investigators in the development of research protocols that are best suited to the assessment of clinical outcomes of osteopathic medical practice. Toward this end, the central osteopathic medical principles are heuristically interpreted and elaborated, with the intention of facilitating the formulation of fundamental questions by researchers in the various biomedical disciplines and the design of clinical research projects by osteopathic physicians. A few of the questions evoked by such elaboration of the osteopathic medical principles and awaiting study are suggested for consideration by researchers. Such research questions require and, in part, compose a research paradigm that differs basically from, yet complements and "completes," the prevailing and highly productive reductionist paradigm. It is, in the original sense of the word, a "holistic" paradigm that places emphasis on the organismic context in which the biological mechanisms exist and operate. Conventional clinical research protocols for the assessment of efficacy of most chemical and physical therapeutic agents are ill-suited for the assessment of osteopathic medical care, of manipulative treatment in particular. It is emphasized that osteopathic medical care must be evaluated as it is practiced and not as a contrived, unreal version; and that it must be tested as a derivative of, and in the context of, that philosophy by criteria consonant with that philosophy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗