Accurate Knowledge (accurate + knowledge)

Distribution by Scientific Domains


Selected Abstracts


Relative importance of different dispersal vectors for small aquatic invertebrates in a rock pool metacommunity

ECOGRAPHY, Issue 5 2008
Bram Vanschoenwinkel
The extent and frequency of passive overland dispersal of freshwater invertebrates as well as the relative importance of different dispersal vectors is not well documented. Although anecdotal evidence subscribing the feasibility of individual vectors in various aquatic systems is abundant, dispersal rates have rarely been quantified for different vectors in one study system. Earlier studies also usually investigated dispersal potential rather than actual dispersal rates. In this study we have estimated passive dispersal rates of invertebrate propagules within a cluster of temporary rock pools via water, wind and amphibians in a direct way. Overflows after heavy rains mediated dispersal of a large number of propagules through eroded channels between pools, which were collected in overflow traps. Taking into account model based predictions of overflow frequency, this corresponds with average dispersal rates of 4088 propagules/channel yr,1. Wind dispersal rates as measured by numbers of propagules collected on sticky traps mounted between pool basins were very high (average dispersal rate: 649 propagules m,2 in one month) and were positively related to the proximity of source populations. Finally, invertebrate propagules were also isolated from the faeces of African clawed frogs Xenopus laevis caught from the pools (on average 368 propagules/frog). The combination of short distance wind and overflow dispersal rates likely explain the dominant species sorting and mass effect patterns observed in the metacommunity in a previous study. Amphibian mediated dispersal was much less important as the Xenopus laevis population was small and migrations very rare. Based on our own results and available literature we conclude that both vector and propagule properties determine local passive dispersal dynamics of freshwater invertebrates. Accurate knowledge on rates and vectors of dispersal in natural systems are a prerequisite to increase our understanding of the impact of dispersal on ecology (colonisation, community assembly, coexistence) and evolution (gene flow, local adaptation) in fragmented environments. [source]


Carbon-13 chemical shift anisotropy in DNA bases from field dependence of solution NMR relaxation rates,

MAGNETIC RESONANCE IN CHEMISTRY, Issue 3 2006
Jinfa Ying
Abstract Knowledge of 13C chemical shift anisotropy (CSA) in nucleotide bases is important for the interpretation of solution-state NMR relaxation data in terms of local dynamic properties of DNA and RNA. Accurate knowledge of the CSA becomes particularly important at high magnetic fields, prerequisite for adequate spectral resolution in larger oligonucleotides. Measurement of 13C relaxation rates of protonated carbons in the bases of the so-called Dickerson dodecamer, d(CGCGAATTCGCG)2, at 500 and 800 MHz 1H frequency, together with the previously characterized structure and diffusion tensor yields CSA values for C5 in C, C6 in C and T, C8 in A and G, and C2 in A that are closest to values previously reported on the basis of solid-state FIREMAT NMR measurements, and mostly larger than values obtained by in vacuo DFT calculations. Owing to the noncollinearity of dipolar and CSA interactions, interpretation of the NMR relaxation rates is particularly sensitive to anisotropy of rotational diffusion, and use of isotropic diffusion models can result in considerable errors. Copyright © 2006 John Wiley & Sons, Ltd. [source]


Factors influencing treatment for depression among medical students: a nationwide sample in South Korea

MEDICAL EDUCATION, Issue 2 2009
Myoung-Sun Roh
Objectives, Depression is more frequently experienced and induces more severe consequences in medical students than in the general population. However, treatment rates for depression in medical students are still low. In this study, the authors investigated factors that affect treatment for depression and dispositions towards treating depression among South Korean medical students. Methods, A nationwide, cross-sectional survey was administered to medical students attending all 41 medical schools in South Korea (14 095 students). The questionnaire included the Beck Depression Inventory (BDI) and asked for data on socio-demographic variables, history of diagnosis or treatment for depression, knowledge of mental health problems and disposition to use mental health care. Results, A total of 7357 students (52.2%) from 36 schools responded to the survey. Of these, 689 (9.4%) were identified as being depressed via a BDI score higher than 16. Of the depressed respondents, only 61 (8.9%) had been diagnosed with depression and 67 (9.7%) had been treated for depression. Age was significantly associated with treatment behaviour for depression. Correct knowledge about the aetiology of depression and psychiatric medicine was significantly related to students' disposition to use psychiatric services and to receive psychopharmacotherapy as an option to resolve depression. Conclusions, Accurate knowledge of depression and appropriate medication seems to be relevant to students seeking appropriate treatment for depression. The development of education programmes designed to improve medical students' knowledge of mental health problems and treatments would facilitate treatment seeking in medical students. [source]


Specific Opposition: Judd's art and politics

ART HISTORY, Issue 5 2001
David Raskin
Donald Judd was a sceptic. He objected to impositions on free thinking, especially when set modes of belief interfered with good art or civil liberties. Accurate knowledge about the world, he believed, could only be acquired by subjecting traditionally held beliefs, values and habits of mind to empirical testing. In discussing Judd's works of art in the context of his empirical aesthetics and anarchist politics, I draw from some eleven archives, addressing, in secession, his materialist scepticism, formal and political anarchy, and Cold War pacifism. In so doing, I show the interdependence of Judd's art and politics, and explain how both are hostile to conventions of power. [source]


GAPs in Slit-Robo signaling

BIOESSAYS, Issue 5 2002
Aurnab Ghose
Neuronal migration requires the integration of a number of diverse environmental cues and subsequent translation to specific responses such as directed cytoskeletal remodeling. Accurate knowledge of the signal transduction pathways linking activation of surface receptors to actin dynamics is necessary in order to understand the regulation of such processes. Activation of the Roundabout (Robo) receptor mediates a repulsive response in certain pioneering axons and migratory neurons. Recently, Wong et al.1 have described a signaling link between Robo activation and specific GTPase activity that appears to regulate neuronal migration. A novel family of GTPase regulators, responsive to Slit-Robo engagement, has been identified and convincingly shown to alter the migration of neuronal cells. This study not only delineates a specific signaling route from guidance receptors to directed neuronal movement, but also offers clues towards potential regulatory mechanisms that ensure specificity of the Slit-Robo response. BioEssays 24:401,404, 2002. © 2002 Wiley Periodicals, Inc. [source]


Value of combined 6-[18F]fluorodihydroxyphenylalanine PET/CT for imaging of neuroendocrine tumours,

BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 5 2010
M. Schiesser
Background: Accurate knowledge of tumour presence and location is essential to treat neuroendocrine tumours (NETs). Standard imaging has been hampered by low sensitivity and lack of spatial resolution. This study assessed prospectively the diagnostic value and impact of combined 6-[18F]fluorodihydroxyphenylalanine positron emission tomography,computed tomography (18F-DOPA-PET/CT) in the management of NET. Methods: 18F-DOPA-PET/CT findings in 61 patients with suspected NET were compared with a composite reference standard including somatostatin receptor scintigraphy (SRS), magnetic resonance imaging, computed tomography, histological examination and clinical follow-up. The impact on clinical management was estimated by calculating the proportion of patients whose treatment changed as a result of 18F-DOPA-PET/CT findings. Results: 18F-DOPA-PET/CT correctly identified 32 of 36 patients with NET. The sensitivity and specificity of 18F-DOPA-PET/CT for the detection of NET were 91 and 96 per cent respectively. Sensitivity using SRS was significantly lower (59 per cent), whereas the specificity was similar (86 per cent). In 16 (26 per cent) of the 61 patients the management was altered as a result of new findings on 18F-DOPA-PET/CT. Conclusion: 18F-DOPA-PET/CT yields a high sensitivity and specificity in the detection of NET. The clinical impact was highly relevant as changes in therapy were observed in more than a quarter of the patients. Copyright © 2010 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source]


Understanding AIDS: A Comparison of Children in the United States and Thailand,

FAMILY RELATIONS, Issue 4 2001
Margaret H. Young
Replicating a prior U.S. study, data were gathered from preschool and school-age children in Thailand (n= 80). Taking a developmental perspective, Thai children's knowledge and understanding of AIDS was assessed, and results were compared with those of the U.S. sample. The findings show that Thai children in each of four designated age groups have higher levels of accurate knowledge of AIDS compared with their U.S. counterparts. The findings of these early studies are discussed in terms of current AIDS infection rates and educational prevention efforts in both cultures. [source]


Racial/Ethnic Disparities in Knowledge about Risks and Benefits of Breast Cancer Treatment: Does It Matter Where You Go?

HEALTH SERVICES RESEARCH, Issue 4 2008
Sarah T. Hawley
Objective. To evaluate the association between provider characteristics and treatment location and racial/ethnic minority patients' knowledge of breast cancer treatment risks and benefits. Data Sources/Data Collection. Survey responses and clinical data from breast cancer patients of Detroit and Los Angeles SEER registries were merged with surgeon survey responses (N=1,132 patients, 277 surgeons). Study Design. Cross-sectional survey. Multivariable regression was used to identify associations between patient, surgeon, and treatment setting factors and accurate knowledge of the survival benefit and recurrence risk related to mastectomy and breast conserving surgery with radiation. Principal Findings. Half (51 percent) of respondents had survival knowledge, while close to half (47.6 percent) were uncertain regarding recurrence knowledge. Minority patients and those with lower education were less likely to have adequate survival knowledge and more likely to be uncertain regarding recurrence risk than their counterparts (p<.001). Neither surgeon characteristics nor treatment location attenuated racial/ethnic knowledge disparities. Patient,physician communication was significantly (p<.001) associated with both types of knowledge, but did not influence racial/ethnic differences in knowledge. Conclusions. Interventions to improve patient understanding of the benefits and risks of breast cancer treatments are needed across surgeons and treatment setting, particularly for racial/ethnic minority women with breast cancer. [source]


Age-dependent histoarchitectural changes in human lymph nodes: an underestimated process with clinical relevance?

JOURNAL OF ANATOMY, Issue 5 2010
Catarina Hadamitzky
Abstract Experimental evidence indicates that lymph nodes in humans undergo alterations during ageing. This is clinically important because of the crucial role of these organs in the immune system and their lymph reabsorption and drainage function. Although some age-related changes in lymph node histoarchitecture have been described, they are seldom taken into account in traditional depictions of lymph nodes. Recently introduced clinical procedures, such as intranodal vaccination or lymph node transplantation, have demonstrated the need for an accurate knowledge of these degenerative processes. In this study, superficial inguinal lymph nodes were obtained from 41 deceased patients between 17 and 98 years old. To minimize immunological influences, such as chronic diseases, specimens were only obtained from forensic pathology autopsies. An immunohistochemical analysis was carried out, on the basis of which lymph node degeneration was scored according to the numbers of lymphocytes and high endothelial venules, and degree of fibrosis and lipomatosis. We observed an age-dependent tendency towards the replacement of areas populated with diverse immune cells by connective tissue. Paradoxically, these changes were also detected in some of the nodes from younger age groups. In conclusion, lymph nodes can display degenerative changes that are mainly age-related and often diverge from the common description found in textbooks. These alterations should be taken into account when dealing with lymph nodes diagnostically and therapeutically in clinical practice. [source]


Two years of Visual Odometry on the Mars Exploration Rovers

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 3 2007
Mark Maimone
NASA's two Mars Exploration Rovers (MER) have successfully demonstrated a robotic Visual Odometry capability on another world for the first time. This provides each rover with accurate knowledge of its position, allowing it to autonomously detect and compensate for any unforeseen slip encountered during a drive. It has enabled the rovers to drive safely and more effectively in highly sloped and sandy terrains and has resulted in increased mission science return by reducing the number of days required to drive into interesting areas. The MER Visual Odometry system comprises onboard software for comparing stereo pairs taken by the pointable mast-mounted 45 deg FOV Navigation cameras (NAVCAMs). The system computes an update to the 6 degree of freedom rover pose (x, y, z, roll, pitch, yaw) by tracking the motion of autonomously selected terrain features between two pairs of 256×256 stereo images. It has demonstrated good performance with high rates of successful convergence (97% on Spirit, 95% on Opportunity), successfully detected slip ratios as high as 125%, and measured changes as small as 2 mm, even while driving on slopes as high as 31 deg. Visual Odometry was used over 14% of the first 10.7 km driven by both rovers. During the first 2 years of operations, Visual Odometry evolved from an "extra credit" capability into a critical vehicle safety system. In this paper we describe our Visual Odometry algorithm, discuss several driving strategies that rely on it (including Slip Checks, Keep-out Zones, and Wheel Dragging), and summarize its results from the first 2 years of operations on Mars. © 2006 Wiley Periodicals, Inc. [source]


Supporting inquiry learning by promoting normative understanding of multivariable causality

JOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 9 2003
Alla Keselman
Early adolescents may lack the cognitive and metacognitive skills necessary for effective inquiry learning. In particular, they are likely to have a nonnormative mental model of multivariable causality in which effects of individual variables are neither additive nor consistent. Described here is a software-based intervention designed to facilitate students' metalevel and performance-level inquiry skills by enhancing their understanding of multivariable causality. Relative to an exploration-only group, sixth graders who practiced predicting an outcome (earthquake risk) based on multiple factors demonstrated increased attention to evidence, improved metalevel appreciation of effective strategies, and a trend toward consistent use of a controlled comparison strategy. Sixth graders who also received explicit instruction in making predictions based on multiple factors showed additional improvement in their ability to compare multiple instances as a basis for inferences and constructed the most accurate knowledge of the system. Gains were maintained in transfer tasks. The cognitive skills and metalevel understanding examined here are essential to inquiry learning. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 898,921, 2003 [source]


Perceived barriers to adherence among adolescent renal transplant candidates

PEDIATRIC TRANSPLANTATION, Issue 3 2008
Nataliya Zelikovsky
Abstract:, Non-adherence to medical regimens is a ubiquitous hindrance to quality health care among adolescent transplant recipients. Identification of potentially modifiable barriers to adherence when patients are listed for organ transplant would help with early intervention efforts to prepare adolescents for the stringent medication regimen post-transplant. Fifty-six adolescents listed for a kidney transplant, mean age 14.27 (s.d. = 2.2; range 11,18 yr), 73.2% male, 62.5% Caucasian participated in a semi-structured interview, the Medical Adherence Measure, to assesses the patient's knowledge of the prescribed regimen, reported adherence (missed and late doses), the system used to organized medications, and who holds the primary responsibility over medication management. Better knowledge of the medication regimen was associated with fewer missed doses (r = ,0.48, p < 0.001). Patients who perceived more barriers had more missed (r = 0.38, p = 0.004) and late (r = 0.47, p < 0.001) doses. Patients who endorsed "just forget," the most common barrier (56.4%), reported significantly more missed (z = ,4.25, p < 0.001) and late (z = ,2.2, p = 0.02) doses. Only one-third of the transplant candidates used a pillbox to organize medications but these patients had significantly better adherence, z = ,2.2, p = 0.03. With regard to responsibility over managing the regimens, adolescents missed fewer doses when their parents were in charge than when they were solely responsible, z = ,2.1, p = 0.04. Interventions developed to prepare transplant candidates for a stringent post-transplant regimen need to focus on ensuring accurate knowledge of as simple a regimen as possible. Use of an organized system such as a pillbox to establish a routine and facilitate tracking of medications is recommended with integration of reminders that may be appealing for this age group. Although individuation is developmentally normative at this age, parent involvement seems critical until the adolescent is able to manage the responsibility more independently. [source]


Surgical history of ancient China: part 1

ANZ JOURNAL OF SURGERY, Issue 12 2009
Louis Fu
Abstract Although surgery was an accepted and quite proficient craft very early on in Chinese history, it has deteriorated through the ages. Despite the fact that anaesthetic agents in major surgery were employed during the third century, Chinese surgery is conspicuous by its stagnation. Reverence for the dead, filial piety, abhorrence of shedding blood and other conservative attitudes make it impossible for any accurate knowledge of the human anatomy and physiology, without which surgery cannot progress. This article surveys some highlights in the history of surgery in ancient China and examines the factors responsible for its decline. The second concluding part deals with orthopaedics. [source]