12 results on '"Fredericks D"'
Search Results
2. Arsenic hazard in shallow Cambodian groundwaters
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Polya, D. A., Gault, A. G., Diebe, N., Feldman, P., Rosenboom, J. W., Gilligan, E., Fredericks, D., Milton, A. H., Sampson, M., Rowland, H. A. L., Lythgoe, P. R., Jones, J. C., Middleton, C., and Cooke, D. A.
- Abstract
AbstractOur recent discovery of hazardous concentrations of arsenic in shallow sedimentary aquifers in Cambodia raises the spectre of future deleterious health impacts on a population that, particularly in non-urban areas, extensively use untreated groundwater as a source of drinking water and, in some instances, as irrigation water. We present here small-scale hazard maps for arsenic in shallow Cambodian groundwaters based on >1000 groundwater samples analysed in the Manchester Analytical Geochemistry Unit and elsewhere. Key indicators for hazardous concentrations of arsenic in Cambodian groundwaters include: (1) well depths greater than 16 m; (2) Holocene host sediments; and (3) proximity to major modern channels of the Mekong (and its distributary the Bassac). However, high-arsenic well waters are also commonly found in wells not exhibiting these key characteristics, notably in some shallower Holocene wells, and in wells drilled into older Quaternary and Neogene sediments.It is emphasized that the maps and tables presented are most useful for identifying current regional trends in groundwater arsenic hazard and that their use for predicting arsenic concentrations in individual wells, for example for the purposes of well switching, is not recommended, particularly because of the lack of sufficient data (especially at depths >80 m) and because, as in Bangladesh and West Bengal, there is considerable heterogeneity of groundwater arsenic concentrations on a scale of metres to hundreds of metres. We have insufficient data at this time to determine unequivocally whether or not arsenic concentrations are increasing in shallow Cambodian groundwaters as a result of groundwater-abstraction activities.
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- 2005
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3. The relationship between sediment and water quality, and riverine sediment loads in the wave-dominated estuaries of south-west Western Australia
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Radke, L. C., Prosser, I. P., Robb, M., Brooke, B., Fredericks, D., Douglas, G. B., and Skemstad, J.
- Abstract
We examine surface sediment and water column total nutrient and chlorophyll a concentrations for 12 estuaries with average water depths <4 m, and calculated sediment loads ranging from 0.2 to 10.8 kg m?2 year?1. Sediment total nitrogen, phosphorus and organic carbon concentrations vary inversely with sediment loads due to: (i) the influx of more mineral-rich sediment into the estuaries; and (ii) increasing sediment sulfidation. Sediment total organic carbon (TOC):total sulfur (TS) and TS:Fe(II) ratios correlated to sediment loads because enhanced sedimentation increases burial, hence the importance of sulfate reduction in organic matter degradation. Curvilinear relationships were found between a weathering index and organic matter ?13C in sediment, and sediment load. The rising phase of the curve (increasing weathering, lighter isotopic values) at low to intermediate loads relates to soil erosion, whereas regolith or bedrock erosion probably explains the declining phase of the curve (decreasing weathering, heavier isotopic values) at higher sediment loads. The pattern of change for water column total nutrients (nitrogen and phosphorus) with sediment loads is similar to that of the weathering index. Most water quality problems occur in association with soil erosion, and at sediment loads that are intermediate for the estuaries studied. Limited evidence is presented that flushing can moderate the impact of sediment loads upon the estuaries.
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- 2004
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4. Overview of the treatment of rumination disorder for adults in a residential setting
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Fredericks, D. W., Carr, J. E., and Williams, W. L.
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- 1998
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5. Sequence-based identification of microbial pathogens: a reconsideration of Koch's postulates
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Fredericks, D N and Relman, D A
- Abstract
Over 100 years ago, Robert Koch introduced his ideas about how to prove a causal relationship between a microorganism and a disease. Koch's postulates created a scientific standard for causal evidence that established the credibility of microbes as pathogens and led to the development of modern microbiology. In more recent times, Koch's postulates have evolved to accommodate a broader understanding of the host-parasite relationship as well as experimental advances. Techniques such as in situ hybridization, PCR, and representational difference analysis reveal previously uncharacterized, fastidious or uncultivated, microbial pathogens that resist the application of Koch's original postulates, but they also provide new approaches for proving disease causation. In particular, the increasing reliance on sequence-based methods for microbial identification requires a reassessment of the original postulates and the rationale that guided Koch and later revisionists. Recent investigations of Whipple's disease, human ehrlichiosis, hepatitis C, hantavirus pulmonary syndrome, and Kaposi's sarcoma illustrate some of these issues. A set of molecular guidelines for establishing disease causation with sequence-based technology is proposed, and the importance of the scientific concordance of evidence in supporting causal associations is emphasized.
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- 1996
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6. Polymerase chain reaction—based detection of Tropheryma whippeliiin central nervous system Whipple's disease
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Lynch, T., Odel, J., Fredericks, D. N., Louis, E. D., Forman, S., Rotterdam, H., Fahn, S., and Relman, D. A.
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Whipple's disease of the central nervous system (CNS) may be associated with normal intestinal histology as a result of minimal or patchy involvement. The diagnosis is difficult and is frequently made post mortem. We studied 6 patients with clinically suspected CNS Whipple's disease; 2 had oculomasticatory myorhythmia (OMM) fitting criteria for a diagnosis of definite CNS Whipple's disease. One of the 2 had duodenal histology highly suggestive of Whipple's disease; the other 5 patients had normal duodenal histology. DNA was extracted from paraffin‐embedded duodenal tissues in all patients and frozen pontine tissue in 1. Two primer pairs (WF‐WR, W3F‐W2R) were used in separate polymerase chain reactions (PCRs) to amplify fragments of Tropheryma whippelii16S rDNA from these tissue samples. PCR amplicons were detected only in the duodenal tissues from the 2 patients with OMM. The sequences of these amplicons were identical to the corresponding region of the previously published Tropheryma whippelii16S rDNA sequence. PCR‐based assays of intestinal or brain tissue may be of value for confirming, and possibly refuting, a clinical diagnosis of CNS Whipple's disease in a patient with any combination of dementia, supranuclear gaze palsy, hypothalamic manifestations, myoclonus, seizures, ataxia, or OMM, especially when tissue histology is unrevealing.
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- 1997
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7. How we learned to love RVing.
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Fredericks, D.
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POSTCARDS - Abstract
Recalls how a series of picture post cards enticed this couple to sample the mobile lifestyle.
- Published
- 1989
8. LO44: Initial validation of the core components in the SHoC-Hypotension Protocol. What rates of ultrasound findings are reported in emergency department patients with undifferentiated hypotension? Results from the first Sonography in Hypotension and Cardiac Arrest in the Emergency Department (SHOC-ED1) Study; an international randomized controlled trial
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Lussier, D., Pham, C., Milne, J., Lewis, D., Diegelmann, L., Lamprecht, H., Henneberry, R., Fraser, J., Stander, M., van Hoving, D.J., Fredericks, D., Howlett, M., Mekwan, J., Ramrattan, B., Middleton, J., Olszynski, P., Peach, M., Taylor, L., Dahn, T., Hurley, S.T., MacSween, K., Cox, C., Hunter, S., Bowra, J., Lambert, M., Jarman, R., Harris, T., Noble, V., Connolly, J., and Atkinson, P.R.
- Abstract
Introduction:Point of care ultrasound (PoCUS) has become an established tool in the initial management of patients with undifferentiated hypotension in the emergency department (ED). Current established protocols (e.g. RUSH and ACES) were developed by expert user opinion, rather than objective, prospective data. Recently the SHoC Protocol was published, recommending 3 core scans; cardiac, lung, and IVC; plus other scans when indicated clinically. We report the abnormal ultrasound findings from our international multicenter randomized controlled trial, to assess if the recommended 3 core SHoC protocol scans were chosen appropriately for this population. Methods:Recruitment occurred at seven centres in North America (4) and South Africa (3). Screening at triage identified patients (SBP<100 or shock index>1) who were randomized to PoCUS or control (standard care with no PoCUS) groups. All scans were performed by PoCUS-trained physicians within one hour of arrival in the ED. Demographics, clinical details and study findings were collected prospectively. A threshold incidence for positive findings of 10% was established as significant for the purposes of assessing the appropriateness of the core recommendations. Results:138 patients had a PoCUS screen completed. All patients had cardiac, lung, IVC, aorta, abdominal, and pelvic scans. Reported abnormal findings included hyperdynamic LV function (59; 43%); small collapsing IVC (46; 33%); pericardial effusion (24; 17%); pleural fluid (19; 14%); hypodynamic LV function (15; 11%); large poorly collapsing IVC (13; 9%); peritoneal fluid (13; 9%); and aortic aneurysm (5; 4%). Conclusion:The 3 core SHoC Protocol recommendations included appropriate scans to detect all pathologies recorded at a rate of greater than 10 percent. The 3 most frequent findings were cardiac and IVC abnormalities, followed by lung. It is noted that peritoneal fluid was seen at a rate of 9%. Aortic aneurysms were rare. This data from the first RCT to compare PoCUS to standard care for undifferentiated hypotensive ED patients, supports the use of the prioritized SHoC protocol, though a larger study is required to confirm these findings.
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- 2017
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9. LO07: Does point of care ultrasonography improve diagnostic accuracy in emergency department patients with undifferentiated hypotension? The first Sonography in Hypotension and Cardiac Arrest in the Emergency Department (SHOC-ED1) Study; an international randomized controlled trial
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Peach, M., Milne, J., Lewis, D., Diegelmann, L., Lamprecht, H., Stander, M., Lussier, D., Pham, C., Henneberry, R., Fraser, J., Howlett, M., Mekwan, J., Ramrattan, B., Middleton, J., van Hoving, D.J., Fredericks, D., Taylor, L., Dahn, T., Hurley, S.T., MacSween, K., Cox, C., Richardson, L., Loubani, O., Stoica, G., Hunter, S., Olszynski, P., and Atkinson, P.R.
- Abstract
Introduction:Point of care ultrasonography (PoCUS) is an established tool in the initial management of hypotensive patients in the emergency department (ED). It has been shown rule out certain shock etiologies, and improve diagnostic certainty, however evidence on benefit in the management of hypotensive patients is limited. We report the findings from our international multicenter RCT assessing the impact of a PoCUS protocol on diagnostic accuracy, as well as other key outcomes including mortality, which are reported elsewhere. Methods:Recruitment occurred at 4 North American and 3 Southern African sites. Screening at triage identified patients (SBP<100 mmHg or shock index >1) who were randomized to either PoCUS or control groups. Scans were performed by PoCUS-trained physicians. Demographics, clinical details and findings were collected prospectively. Initial and secondary diagnoses were recorded at 0 and 60 minutes, with ultrasound performed in the PoCUS group prior to secondary assessment. Final chart review was blinded to initial impressions and PoCUS findings. Categorical data was analyzed using Fishers two-tailed test. Our sample size was powered at 0.80 (α:0.05) for a moderate effect size. Results:258 patients were enrolled with follow-up fully completed. Baseline comparisons confirmed effective randomization. The perceived shock category changed more frequently in the PoCUS group 20/127 (15.7%) vs. control 7/125 (5.6%); RR 2.81 (95% CI 1.23 to 6.42; p=0.0134). There was no significant difference in change of diagnostic impression between groups PoCUS 39/123 (31.7%) vs control 34/124 (27.4%); RR 1.16 (95% CI 0.786 to 1.70; p=0.4879). There was no significant difference in the rate of correct category of shock between PoCUS (118/127; 93%) and control (113/122; 93%); RR 1.00 (95% CI 0.936 to 1.08; p=1.00), or for correct diagnosis; PoCUS 90/127 (70%) vs control 86/122 (70%); RR 0.987 (95% CI 0.671 to 1.45; p=1.00). Conclusion:This is the first RCT to compare PoCUS to standard care for undifferentiated hypotensive ED patients. We found that the use of PoCUS did change physicians’ perceived shock category. PoCUS did not improve diagnostic accuracy for category of shock or diagnosis.
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- 2017
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10. LO43: Does point of care ultrasound improve resuscitation markers in emergency department patients with undifferentiated hypotension? The first Sonography in Hypotension and Cardiac Arrest in the Emergency Department (SHOC-ED 1) Study; an international randomized controlled trial
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Taylor, L., Milne, J., Lewis, D., Diegelmann, L., Lamprecht, H., Stander, M., Lussier, D., Pham, C., Henneberry, R., Fraser, J., Howlett, M., Mekwan, J., Ramrattan, B., Middleton, J., van Hoving, D.J., Fredericks, D., Peach, M., Dahn, T., Hurley, S.T., MacSween, K., Cox, C., Richardson, L., Loubani, O., Stoica, G., Hunter, S., Olszynski, P., and Atkinson, P.R.
- Abstract
Introduction:Point of Care Ultrasound (PoCUS) protocols are commonly used to guide resuscitation for emergency department (ED) patients with undifferentiated non-traumatic hypotension. While PoCUS has been shown to improve early diagnosis, there is a minimal evidence for any outcome benefit. We completed an international multicenter randomized controlled trial (RCT) to assess the impact of a PoCUS protocol on key resuscitation markers in this group. We report diagnostic impact and mortality elsewhere. Methods:The SHoC-ED1 study compared the addition of PoCUS to standard care within the first hour in the treatment of adult patients presenting with undifferentiated hypotension (SBP<100 mmHg or a Shock Index >1.0) with a control group that did not receive PoCUS. Scans were performed by PoCUS-trained physicians. 4 North American, and 3 South African sites participated in the study. Resuscitation outcomes analyzed included volume of fluid administered in the ED, changes in shock index (SI), modified early warning score (MEWS), venous acid-base balance, and lactate, at one and four hours. Comparisons utilized a T-test as well as stratified binomial log-regression to assess for any significant improvement in resuscitation amount the outcomes. Our sample size was powered at 0.80 (α:0.05) for a moderate effect size. Results:258 patients were enrolled with follow-up fully completed. Baseline comparisons confirmed effective randomization. There was no significant difference in mean total volume of fluid received between the control (1658 ml; 95%CI 1365-1950) and PoCUS groups (1609 ml; 1385-1832; p=0.79). Significant improvements were seen in SI, MEWS, lactate and bicarbonate with resuscitation in both the PoCUS and control groups, however there was no difference between groups. Conclusion:SHOC-ED1 is the first RCT to compare PoCUS to standard of care in hypotensive ED patients. No significant difference in fluid used, or markers of resuscitation was found when comparing the use of a PoCUS protocol to that of standard of care in the resuscitation of patients with undifferentiated hypotension.
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- 2017
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11. LO45: Does the use of point of care ultrasonography improve survival in emergency department patients with undifferentiated hypotension? The first Sonography in Hypotension and Cardiac Arrest in the Emergency Department (SHOC-ED1) Study; an international randomized controlled trial
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Atkinson, P.R., Milne, J., Diegelmann, L., Lamprecht, H., Stander, M., Lussier, D., Pham, C., Henneberry, R., Fraser, J., Howlett, M., Mekwan, J., Ramrattan, B., Middleton, J., van Hoving, D.J., Fredericks, D., Peach, M., Taylor, L., Dahn, T., Hurley, S.T., MacSween, K., Cox, C., Richardson, L., Loubani, O., Stoica, G., Hunter, S., Olszynski, P., and Lewis, D.
- Abstract
Introduction:Point of care ultrasound (PoCUS) is an established tool in the initial management of patients with undifferentiated hypotension in the emergency department (ED). While PoCUS protocols have been shown to improve early diagnostic accuracy, there is little published evidence for any mortality benefit. We report the findings from our international multicenter randomized controlled trial, assessing the impact of a PoCUS protocol on survival and key clinical outcomes. Methods:Recruitment occurred at 7 centres in North America (4) and South Africa (3). Scans were performed by PoCUS-trained physicians. Screening at triage identified patients (SBP<100 or shock index>1), randomized to PoCUS or control (standard care and no PoCUS) groups. Demographics, clinical details and study findings were collected prospectively. Initial and secondary diagnoses were recorded at 0 and 60 minutes, with ultrasound performed in the PoCUS group prior to secondary assessment. The primary outcome measure was 30-day/discharge mortality. Secondary outcome measures included diagnostic accuracy, changes in vital signs, acid-base status, and length of stay. Categorical data was analyzed using Fishers test, and continuous data by Student T test and multi-level log-regression testing. (GraphPad/SPSS) Final chart review was blinded to initial impressions and PoCUS findings. Results:258 patients were enrolled with follow-up fully completed. Baseline comparisons confirmed effective randomization. There was no difference between groups for the primary outcome of mortality; PoCUS 32/129 (24.8%; 95% CI 14.3-35.3%) vs. Control 32/129 (24.8%; 95% CI 14.3-35.3%); RR 1.00 (95% CI 0.869 to 1.15; p=1.00). There were no differences in the secondary outcomes; ICU and total length of stay. Our sample size has a power of 0.80 (α:0.05) for a moderate effect size. Other secondary outcomes are reported separately. Conclusion:This is the first RCT to compare PoCUS to standard care for undifferentiated hypotensive ED patients. We did not find any mortality or length of stay benefits with the use of a PoCUS protocol, though a larger study is required to confirm these findings. While PoCUS may have diagnostic benefits, these may not translate into a survival benefit effect.
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- 2017
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12. Clustering Patterns of Monarch Butterflies (Lepidoptera: Danaidae) at Two California Central Coast Overwintering Sites
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Frey, D., Leong, K.L.H., Fredericks, D., and Raskowitz, S.
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The behavioral ecology of monarch butterflies, Danaus plexippus (L.), was studied during the 1988-1989 and 1989-1990 overwintering seasons at two central coastal sites in San Luis Obispo County, Calif., that differ in stand composition. In both seasons, patterns of tree use were similar at both sites; fewer trees supported clustering individuals as the season progressed, even though population levels remained constant. Tree use was not random, and as few as 3% of the available trees accounted for 97% of the clustering. A method of describing the location of clusters on specific trees was developed. Roosting individuals were consistently found on the southern exposures of trees, and cluster locations varied neither diurnally nor seasonally. Microclimate variables such as solar radiation, temperature, and wind were not good predictors of clustering position on trees within sites.
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- 1992
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