Sensory uncertainty governs the extent of audio-visual interaction.
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Auditory signals have been shown to exert a marked influence on visual perception in a wide range of tasks. However, the mechanisms of these interactions are, at present, poorly understood. Here we present a series of experiments where a temporal cue within the auditory domain can significantly affect the localisation of a moving visual target. To investigate the mechanism of this interaction, we first modulated the spatial positional uncertainty of the visual target by varying its size. When visual positional uncertainty was low (small target size), auditory signals had little or no influence on perceived visual location. However, with increasing visual uncertainty (larger target sizes), auditory signals exerted a significantly greater influence on perceived visual location. We then altered the temporal profile of the auditory signal by modulating the spread of its Gaussian temporal envelope. Introducing this temporal uncertainty to the auditory signal greatly reduced its effect on visual localisation judgements. These findings support the view that the relative uncertainty in individual sensory domains governs the perceptual outcome of multisensory integration. (+info)
Genome wide expression profiling of angiogenic signaling and the Heisenberg uncertainty principle.
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Genome wide DNA expression profiling coupled with antibody array experiments using endostatin to probe the angiogenic signaling network in human endothelial cells were performed. The results reveal constraints on the measuring process that are of a similar kind as those implied by the uncertainty principle of quantum mechanics as described by Werner Heisenberg. We describe this analogy and argue for its heuristic utility in the conceptualization of angiogenesis as an important step in tumor formation. (+info)
Calculating the contribution of herpes simplex virus type 2 epidemics to increasing HIV incidence: treatment implications.
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Herpes simplex virus type 2 (HSV-2) is the most prevalent sexually transmitted pathogen worldwide. There is considerable biological and epidemiological evidence that HSV-2 infection increases the risk of acquiring HIV infection and may also increase the risk of transmitting HIV. Here, we use a mathematical model to predict the effect of a high-prevalence HSV-2 epidemic on HIV incidence. Our results show that HSV-2 epidemics can more than double the peak HIV incidence; that the biological heterogeneity in susceptibility and transmission induced by an HSV-2 epidemic causes HIV incidence to rise, fall, and then rise again; and that HSV-2 epidemics concentrate HIV epidemics, creating a "core group" of HIV transmitters. Our modeling results imply that findings from HSV-2 intervention trials aimed at reduction of HIV incidence will be variable and that positive findings will be obtained only from trials in communities in which HIV incidence is steeply rising. (+info)
Cost-effectiveness of zinc as adjunct therapy for acute childhood diarrhoea in developing countries.
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OBJECTIVE: To analyse the incremental costs, effects and cost-effectiveness of zinc used as adjunct therapy to standard treatment of acute childhood diarrhoea, including dysentery, and to reassess the cost-effectiveness of standard case management with oral rehydration salt (ORS). METHODS: A decision tree was used to model expected clinical outcomes and expected costs under four alternative treatment strategies. The best available epidemiological, clinical and economic evidence was used in the calculations, and the United Republic of Tanzania was the reference setting. Probabilistic cost-effectiveness analysis was performed using a Monte-Carlo simulation technique and the potential impacts of uncertainty in single parameters were explored in one-way sensitivity analyses. FINDINGS: ORS was found to be less cost-effective than previously thought. The use of zinc as adjunct therapy significantly improved the cost-effectiveness of standard management of diarrhoea for dysenteric as well as non-dysenteric illness. The results were particularly sensitive to mortality rates in non-dysenteric diarrhoea, but the alternative interventions can be defined as highly cost-effective even in pessimistic scenarios. CONCLUSION: There is sufficient evidence to recommend the inclusion of zinc into standard case management of both dysenteric and non-dysenteric acute diarrhoea.A direct transfer of our findings from the United Republic of Tanzania to other settings is not justified, but there are no indications of large geographical differences in the efficacy of zinc. It is therefore plausible that our findings are also applicable to other developing countries. (+info)
Risk management in patients with severe acute pancreatitis.
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Primary or secondary infection of necrotized areas by enteral bacteria is considered a primary cause of mortality in patients with severe acute pancreatitis (SAP). Indeed, 20-30% of patients die during the course of the disease from multiple organ dysfunction after infection. This is why strategies such as antibiotic prophylaxis and early surgical intervention are appealing, but the controlled data that support these measures are insufficient. On the other hand, environmental risk factors (e.g. smoking, alcohol) and genetic predisposition have been identified; together, these led to SAP being considered a 'multifactorial' disease. However, this description does not help the intensivist to assess risk in the individual patient. A number of prognostic factors in SAP have been identified, and different scoring systems have been developed that include therapy-associated and patient-related factors. Nevertheless, at present no prognostic model is available that takes into account all of these predictors. Moreover, despite several attempts to create guideline-based strategies, SAP is still characterized by rapidly progressive multiple organ failure and high mortality, and both surgical and conservative therapies yield poor outcomes. This brief commentary highlights the most recent developments in risk management for patients with SAP. (+info)
The implications of foveal splitting for saccade planning in reading.
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The human fovea and visual pathways are precisely split: information in one hemifield is initially projected to the contralateral visual cortex. This fundamental anatomical constraint on word recognition in reading has been largely ignored in eye movement research. We explore the consequences of this constraint through analyses of a large corpus of eye movement data, and demonstrate that aspects of saccade planning (target selection, initial landing position) are sensitive to both hemispheres, estimated uncertainty about the identity of the currently fixated word. We interpret these findings in terms of a hemispheric division of labour. We suggest that anatomical, visual and lexical factors all contribute to the decision of where to send the eyes next in reading. (+info)
Testing for statistical discrimination in health care.
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OBJECTIVE: To examine the extent to which doctors' rational reactions to clinical uncertainty ("statistical discrimination") can explain racial differences in the diagnosis of depression, hypertension, and diabetes. DATA SOURCES: Main data are from the Medical Outcomes Study (MOS), a 1986 study conducted by RAND Corporation in three U.S. cities. The study compares the processes and outcomes of care for patients in different health care systems. Complementary data from National Health And Examination Survey III (NHANES III) and National Comorbidity Survey (NCS) are also used. STUDY DESIGN: Across three systems of care (staff health maintenance organizations, multispecialty groups, and solo practices), the MOS selected 523 health care clinicians. A representative cross-section (21,480) of patients was then chosen from a pool of adults who visited any of these providers during a 9-day period. DATA COLLECTION: We analyzed a subsample of the MOS data consisting of patients of white family physicians or internists (11,664 patients). We obtain variables reflecting patients' health conditions and severity, demographics, socioeconomic status, and insurance from the patients' screener interview (administered by MOS staff prior to the patient's encounter with the clinician). We used the reports made by the clinician after the visit to construct indicators of doctors' diagnoses. We obtained prevalence rates from NHANES III and NCS. FINDINGS: We find evidence consistent with statistical discrimination for diagnoses of hypertension, diabetes, and depression. In particular, we find that if clinicians act like Bayesians, plausible priors held by the physician about the prevalence of the disease across racial groups could account for racial differences in the diagnosis of hypertension and diabetes. In the case of depression, we find evidence that race affects decisions through differences in communication patterns between doctors and white and minority patients. CONCLUSIONS: To contend effectively with inequities in health care, it is necessary to understand the mechanisms behind the problem. Discrimination stemming from prejudice is of a very different character than discrimination stemming from the application of rules of conditional probability as a response to clinical uncertainty. While in the former case, doctors are not acting in the best interests of their patients, in the latter, they are doing the best they can, given the information available. If miscommunication is the culprit, then efforts should be aimed at reducing disparities in the ways in which doctors communicate with patients. (+info)
The nature of medical evidence and its inherent uncertainty for the clinical consultation: qualitative study.
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OBJECTIVE: To describe how clinicians deal with the uncertainty inherent in medical evidence in clinical consultations. DESIGN: Qualitative study. SETTING: Clinical consultations related to hormone replacement therapy, bone densitometry, and breast screening in seven general practices and three secondary care clinics in the UK NHS. PARTICIPANTS: Women aged 45-64. RESULTS: 45 of the 109 relevant consultations included sufficient discussion for analysis. The consultations could be categorised into three groups: focus on certainty for now and this test, with slippage into general reassurance; a coherent account of the medical evidence for risks and benefits, but blurring of the uncertainty inherent in the evidence and giving an impression of certainty; and acknowledging the inherent uncertainty of the medical evidence and negotiating a provisional decision. CONCLUSION: Strategies health professionals use to cope with the uncertainty inherent in medical evidence in clinical consultations include the use of provisional decisions that allow for changing priorities and circumstances over time, to avoid slippage into general reassurance from a particular test result, and to avoid the creation of a myth of certainty. (+info)