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160 records – page 1 of 16.

A 14C age calibration curve for the last 60 ka: the Greenland-Hulu U/Th timescale and its impact on understanding the Middle to Upper Paleolithic transition in Western Eurasia.

https://arctichealth.org/en/permalink/ahliterature91637
Source
J Hum Evol. 2008 Nov;55(5):772-81
Publication Type
Article
Date
Nov-2008
Author
Weninger Bernhard
Jöris Olaf
Author Affiliation
Universität zu Köln, Institut für Ur- und Frühgeschichte, Radiocarbon Laboratory, Weyertal 125, 50923 Köln, Germany. b.weninger@uni-koeln.de
Source
J Hum Evol. 2008 Nov;55(5):772-81
Date
Nov-2008
Language
English
Publication Type
Article
Keywords
Animals
Calibration
China
Chronology as Topic
Climate
Greenland
Hominidae
Humans
Paleontology - methods
Radiometric Dating - methods
Abstract
This paper combines the data sets available today for 14C-age calibration of the last 60 ka. By stepwise synchronization of paleoclimate signatures, each of these sets of 14C-ages is compared with the U/Th-dated Chinese Hulu Cave speleothem records, which shows global paleoclimate change in high temporal resolution. By this synchronization we have established an absolute-dated Greenland-Hulu chronological framework, against which global paleoclimate data can be referenced, extending the 14C-age calibration curve back to the limits of the radiocarbon method. Based on this new, U/Th-based Greenland(Hulu) chronology, we confirm that the radiocarbon timescale underestimates calendar ages by several thousand years during most of Oxygen Isotope Stage 3. Major atmospheric 14C variations are observed for the period of the Middle to Upper Paleolithic transition, which has significant implications for dating the demise of the last Neandertals. The early part of "the transition" (with 14C ages > 35.0 ka 14C BP) coincides with the Laschamp geomagnetic excursion. This period is characterized by highly-elevated atmospheric 14C levels. The following period ca. 35.0-32.5 ka 14C BP shows a series of distinct large-scale 14C age inversions and extended plateaus. In consequence, individual archaeological 14C dates older than 35.0 ka 14C BP can be age-calibrated with relatively high precision, while individual dates in the interval 35.0-32.5 ka 14C BP are subject to large systematic age-'distortions,' and chronologies based on large data sets will show apparent age-overlaps of up to ca. 5,000 cal years. Nevertheless, the observed variations in past 14C levels are not as extreme as previously proposed ("Middle to Upper Paleolithic dating anomaly"), and the new chronological framework leaves ample room for application of radiocarbon dating in the age-range 45.0-25.0 ka 14C BP at high temporal resolution.
PubMed ID
18922563 View in PubMed
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Accuracy of the Third Molar Eruption Predictor in predicting eruption.

https://arctichealth.org/en/permalink/ahliterature194372
Source
Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2001 Jun;91(6):638-42
Publication Type
Article
Date
Jun-2001
Author
I. Ventä
S. Schou
Author Affiliation
Department of Oral Medicine, University of Helsinki, Finland. irja.venta@helsinki.fi
Source
Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2001 Jun;91(6):638-42
Date
Jun-2001
Language
English
Publication Type
Article
Keywords
Adult
Bayes Theorem
Calibration
Denmark
False Negative Reactions
False Positive Reactions
Female
Follow-Up Studies
Forecasting - methods
Humans
Male
Molar - radiography
Molar, Third - physiology - radiography
Observer Variation
Odontometry
Probability
Radiography, Panoramic
Retrospective Studies
Sensitivity and specificity
Tooth Crown - radiography
Tooth Eruption
Tooth, Impacted - physiopathology
Tooth, Unerupted - physiopathology - radiography
Abstract
To evaluate the possibility of applying the Third Molar Eruption Predictor to all panoramic radiographs.
Panoramic radiographs were retrospectively analyzed from a 4-year follow-up study of third molars carried out at the University of Copenhagen, Denmark. The radiographs, taken at a mean age of 20.6 years, included 45 unerupted or partially erupted mandibular third molars in 28 subjects. Because the device was calibrated both with simple proportions and by use of the methods of Bayes' Decision Theory, the separation point of the device was therefore adjusted at 12 mm from the distal surface of the second molar.
The predictions of future eruption or impaction made with the calibrated device and the actual clinical outcome 4 years later were in conformity for 80% of the mandibular third molars.
The Third Molar Eruption Predictor may be applied to all panoramic radiographs, but it seems to require calibration before use.
PubMed ID
11402274 View in PubMed
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Adequacy of empirical antifungal therapy and effect on outcome among patients with invasive Candida species infections.

https://arctichealth.org/en/permalink/ahliterature162941
Source
J Antimicrob Chemother. 2007 Sep;60(3):613-8
Publication Type
Article
Date
Sep-2007
Author
Michael D Parkins
Deana M Sabuda
Sameer Elsayed
Kevin B Laupland
Author Affiliation
Department of Medicine, Calgary Health Region and University of Calgary, Calgary, Alberta, Canada.
Source
J Antimicrob Chemother. 2007 Sep;60(3):613-8
Date
Sep-2007
Language
English
Publication Type
Article
Keywords
Adult
Aged
Aged, 80 and over
Alberta - epidemiology
Analysis of Variance
Antifungal Agents - therapeutic use
Calibration
Candida - drug effects
Candidiasis - drug therapy - epidemiology - microbiology
Cohort Studies
Female
Humans
Logistic Models
Male
Microbial Sensitivity Tests
Middle Aged
Odds Ratio
Risk factors
Terminology as Topic
Treatment Outcome
Abstract
Although inadequate antimicrobial therapy has been demonstrated in multiple studies to increase the risk for death in bacterial infections, few data investigating the effect of antifungal therapy on outcome of serious fungal disease are available. We sought to assess the adequacy of empirical therapy and its effect on mortality in invasive Candida species infections.
Population-based surveillance of all patients with Candida spp. cultured from blood and/or cerebrospinal fluid was conducted. Adequacy of empirical therapy was assessed according to published guidelines.
During a 5 year period, 207 patients had an invasive Candida spp. infection identified; in 199 cases (96%) adequate data were available for assessment of treatment and outcome at hospital discharge. One hundred and three (52%) cases were due to Candida albicans, 44 (22%) were due to Candida glabrata and the remainder were due to other species. Between the time of culture draw and reporting of a positive culture, only 64 (32%) patients were treated with empirical therapy; this was deemed adequate in 51 (26%). Patients who received adequate empirical therapy had a significant decrease in crude mortality [14/51 (27%) versus 68/148 (46%); risk ratio 0.60 (95% confidence interval 0.37-0.96); P = 0.02]. After adjusting for age and the need for intensive care unit admission in logistic regression analysis, the use of adequate empirical therapy was independently associated with a reduced risk for death [odds ratio 0.46 (95% confidence interval 0.22-1.00); P = 0.05].
Adequate empirical therapy is used in a minority of patients with invasive Candida spp. infections but is associated with improved survival.
PubMed ID
17576697 View in PubMed
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Airway closure in anesthetized infants and children: influence of inspiratory pressures and volumes.

https://arctichealth.org/en/permalink/ahliterature31558
Source
Acta Anaesthesiol Scand. 2002 May;46(5):529-36
Publication Type
Article
Date
May-2002
Author
A. Thorsteinsson
O. Werner
C. Jonmarker
A. Larsson
Author Affiliation
Department of Anesthesia and Intensive Care, Landspitalinn University Hospital, Hringbraut, Iceland. adalbjn@landspitali.is
Source
Acta Anaesthesiol Scand. 2002 May;46(5):529-36
Date
May-2002
Language
English
Publication Type
Article
Keywords
Adolescent
Air Pressure
Airway Obstruction - etiology
Calibration
Child
Child, Preschool
Elasticity
Female
Functional Residual Capacity
Humans
Infant
Intraoperative Complications - physiopathology
Lung Volume Measurements
Male
Research Support, Non-U.S. Gov't
Respiration, Artificial
Sulfur Hexafluoride - diagnostic use
Abstract
BACKGROUND: Cyclic opening and closing of lung units during tidal breathing may be an important cause of iatrogenic lung injury. We hypothesized that airway closure is uncommon in children with healthy lungs when inspiratory pressures are kept low, but paradoxically may occur when inspiratory pressures are increased. METHODS: Elastic equilibrium volume (EEV) and closing capacity (CC) were measured with a tracer gas (SF(6)) technique in 11 anesthetized, muscle-relaxed, endotracheally intubated and artificially ventilated healthy children, aged 0.6-13 years. Airway closing was studied in a randomized order at two inflation pressures, +20 or +30 cmH(2)O, and CC and CC/EEV were calculated from the plots obtained when the lungs were exsufflated to -20 cmH(2)O. (CC/EEV >1 indicates that airway closure might occur during tidal breathing). Furthermore, a measure of uneven ventilation, multiple breath alveolar mixing efficiency (MBAME), was obtained. RESULTS: Airway closure within the tidal volume (CC/EEV >1) was observed in four and eight children (not significant, NS) after 20 and 30 cmH(2)O inflation, respectively. However, CC(30)/EEV was >CC(20)/EEV in all children (P
PubMed ID
12027847 View in PubMed
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Almost 50 years of monitoring shows that climate, not forestry, controls long-term organic carbon fluxes in a large boreal watershed.

https://arctichealth.org/en/permalink/ahliterature262840
Source
Glob Chang Biol. 2014 Apr;20(4):1225-37
Publication Type
Article
Date
Apr-2014
Author
Ahti Lepistö
Martyn N Futter
Pirkko Kortelainen
Source
Glob Chang Biol. 2014 Apr;20(4):1225-37
Date
Apr-2014
Language
English
Publication Type
Article
Keywords
Calibration
Carbon - analysis
Carbon Cycle
Climate
Droughts
Environmental monitoring
Finland
Floods
Forestry
Models, Theoretical
Seasons
Temperature
Abstract
Here, we use a unique long-term data set on total organic carbon (TOC) fluxes, its climatic drivers and effects of land management from a large boreal watershed in northern Finland. TOC and runoff have been monitored at several sites in the Simojoki watershed (3160 km(2) ) since the early 1960s. Annual TOC fluxes have increased significantly together with increased inter-annual variability. Acid deposition in the area has been low and has not significantly influenced losses of TOC. Forest management, including ditching and clear felling, had a minor influence on TOC fluxes - seasonal and long-term patterns in TOC were controlled primarily by changes in soil frost, seasonal precipitation, drought, and runoff. Deeper soil frost led to lower spring TOC concentrations in the river. Summer TOC concentrations were positively correlated with precipitation and soil moisture not temperature. There is some indication that drought conditions led to elevated TOC concentrations and fluxes in subsequent years (1998-2000). A sensitivity analysis of the INCA-C model results showed the importance of landscape position, land-use type, and soil temperature as controls of modeled TOC concentrations. Model predictions were not sensitive to forest management. Our results are contradictory to some earlier plot-scale and small catchment studies that have shown more profound forest management impacts on TOC fluxes. This shows the importance of scale when assessing the mechanisms controlling TOC fluxes and concentrations. The results highlight the value of long-term multiple data sets to better understand ecosystem response to land management, climate change and extremes in northern ecosystems.
PubMed ID
24501106 View in PubMed
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Amblyopia detection by camera: Gateway to portable, inexpensive vision screening (calibration and validation of inexpensive, pocket-sized photoscreeners).

https://arctichealth.org/en/permalink/ahliterature5344
Source
Alaska Med. 2004 Jul-Sep;46(3):63-72
Publication Type
Article
Author
Robert W Arnold
Andrew W Arnold
Lee Stark
Koni K Arnold
Rachel Leman
M Diane Armitage
Author Affiliation
The Alaska Blind Child Discovery Coordinating Center, Pediatric Ophthalmology and Strabismus, Ophthalmic Associates, 542 West Second Avenue, Anchorage, Alaska 99501-2242, USA.
Source
Alaska Med. 2004 Jul-Sep;46(3):63-72
Language
English
Publication Type
Article
Keywords
Alaska
Amblyopia - diagnosis
Calibration
Child
Child, Preschool
Contact Lenses
Humans
Infant
Photography - instrumentation
Refractive Errors - diagnosis
Research Support, U.S. Gov't, P.H.S.
Vision Screening - economics - instrumentation - methods
Abstract
BACKGROUND: Photoscreening can allow early detection of amblyopia. The Gateway DV-S20, and similar models of miniature, digital flash cameras, have similar optical dimensions to existing photoscreeners for less than $200. METHODS: These cameras were calibrated on known, threshold amblyogenic refractive errors induced by placing minus and toric contact lenses on a normal subject's left eye. The DV-S20 was then applied to known amblyopic patients. Students under age 7 were vision screened with patched acuity and sequential photoscreeners (MTI and Gateway). RESULTS: The digital cameras and the MTI photoscreeners produced similar magnitude interpretable crescents for amblyopiagenic refractive errors. They had very similar validation with sensitivities of 80-90% and specificities of 98% for serious eye disorders in known patients and school-aged children. CONCLUSION: Combined with careful interpretation, pocket-sized, digital flash cameras provide a portable and inexpensive digital alternative for pediatric photoscreening. A category 3 CPT code (0065T) can be used for this valid, public health technique: Amblyopia Detection By Camera (ADBC).
PubMed ID
15839597 View in PubMed
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Analysis of aluminium in serum and urine for the biomonitoring of occupational exposure.

https://arctichealth.org/en/permalink/ahliterature208159
Source
Sci Total Environ. 1997 Jun 20;199(1-2):103-10
Publication Type
Article
Date
Jun-20-1997
Author
S. Valkonen
A. Aitio
Author Affiliation
Finnish Institute of Occupational Health, Department of Industrial Hygiene and Toxicology, Helsinki, Finland.
Source
Sci Total Environ. 1997 Jun 20;199(1-2):103-10
Date
Jun-20-1997
Language
English
Publication Type
Article
Keywords
Adult
Aluminum - blood - urine
Calibration
Environmental Monitoring - methods
Female
Finland
Graphite - chemistry
Humans
Male
Metallurgy
Occupational Exposure
Occupational Medicine - standards - trends
Quality Control
Reference Standards
Reproducibility of Results
Spectrophotometry, Atomic
Abstract
A reliable and sensitive graphite furnace atomic absorption spectrometry (GFAAS) method with Zeeman background correction was developed for the analysis of aluminium in serum and urine in the biological monitoring of aluminium exposure. The method is based on platform atomisation in pyrolytically coated graphite tubes after fourfold dilution with nitric acid. For serum analysis, a matrix matched standard curve is prepared and for urine the method of standard additions is used. The within-run imprecision (C.V.) for serum and urine was 3% and 5%, and the between-day imprecision, 6% and 7.2%, at a concentration level of 4.0 mumol/l. The between-day imprecision for urinary aluminium was 15.7% at a concentration level of 0.24 mumol/l. The detection limits were 0.02 mumol/l for serum and 0.07 mumol/l for urine. During 1 year of participation in TEQAS external quality assessment scheme of the Robens Institute for Health and Safety (Guildford, UK) for serum aluminium the maximum cumulative performance score was achieved. For urinary aluminium a certificate in the external quality control scheme of the German Society of Occupational Medicine was obtained. The mean concentration of aluminium in a non-exposed population, who did not use antacid drugs, was 0.06 mumol/l (S.D. 0.03, range 0.02-0.13, n = 21) in serum, and 0.33 mumol/l (S.D. 0.18, range 0.07-0.82, n = 44) in urine. The upper reference limit for aluminium in a healthy, non-exposed population was estimated to be 0.1 mumol/l in serum and 0.6 mumol/l in urine.
PubMed ID
9200852 View in PubMed
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An uncertainty budget for the measurement of ethanol in blood by headspace gas chromatography.

https://arctichealth.org/en/permalink/ahliterature9348
Source
J Anal Toxicol. 2004 Sep;28(6):456-63
Publication Type
Article
Date
Sep-2004
Author
Jesper Kristiansen
Henning W Petersen
Author Affiliation
The National Institute of Occupational Health, Lersø Parkallé 105, DK-2100 Copenhagen, Denmark.
Source
J Anal Toxicol. 2004 Sep;28(6):456-63
Date
Sep-2004
Language
English
Publication Type
Article
Keywords
Algorithms
Body Water - chemistry
Calibration
Central Nervous System Depressants - blood
Chromatography, Gas
Denmark
Ethanol - blood
Humans
Indicators and Reagents
Reference Standards
Reproducibility of Results
Abstract
An uncertainty budget was constructed for the measurement of ethanol in blood by headspace gas chromatography. The uncertainty budget, covering the analytical range of ethanol concentrations up to 3.00 g/kg, included analytical uncertainty components, traceability uncertainty components, and effects caused by interindividual variation in blood water content. The analytical combined standard uncertainty was estimated from duplicate measurements of real samples and included contributions from headspace recovery, variation between columns, injection, repeatability of analytical signals, and statistical uncertainty of the calibration function. The traceability uncertainty was estimated in a sub-budget based on information about the calibrator and about the preparation of the aqueous standards. Two uncertainty components depended on the interindividual variation in blood water content. First, it caused uncertainty on the density of the blood, and second, it had an effect on the gas phase concentration of ethanol when doing the headspace sampling. These effects as well as their covariance were included in the uncertainty budget. For fresh blood samples, the analytical uncertainty was the dominating uncertainty component, accounting for approximately 90% of the variance. For blood samples collected 100 h postmortem, the interindividual variation in blood water content was the largest uncertainty component. It was demonstrated that subtracting a "safety margin" of 0.1 g/kg from the results was sufficient to keep the risk of committing a type 1 error below 0.1% in ethanol concentrations ranging up to 2 g/kg for fresh blood samples. This risk was higher for postmortem blood samples because of the higher uncertainty of measurement, but still less than approximately 1.4%.
PubMed ID
15516296 View in PubMed
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Application of isotope dilution mass spectrometry: determination of ochratoxin A in the Canadian Total Diet Study.

https://arctichealth.org/en/permalink/ahliterature134090
Source
Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2011 Jun;28(6):754-61
Publication Type
Article
Date
Jun-2011
Author
J. Tam
P. Pantazopoulos
P M Scott
J. Moisey
R W Dabeka
I D K Richard
Author Affiliation
Health Canada-Santé Canada, Ontario Region, Food Laboratories Division, 2301 Midland Avenue, Toronto, ON, Canada.
Source
Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2011 Jun;28(6):754-61
Date
Jun-2011
Language
English
Publication Type
Article
Keywords
Bread - analysis
Calibration
Canada
Carbon Isotopes
Cereals - chemistry
Chromatography, Affinity
Chromatography, High Pressure Liquid
Diet
Fast Foods - analysis
Food Analysis - methods
Food Contamination
Food Habits
Humans
Indicator Dilution Techniques
Limit of Detection
Nutrition Surveys
Ochratoxins - analysis - chemistry - isolation & purification
Reproducibility of Results
Spectrometry, Mass, Electrospray Ionization
Tandem Mass Spectrometry
Abstract
Analytical methods are generally developed and optimized for specific commodities. Total Diet Studies, representing typical food products 'as consumed', pose an analytical challenge since every food product is different. In order to address this technical challenge, a selective and sensitive analytical method was developed suitable for the quantitation of ochratoxin A (OTA) in Canadian Total Diet Study composites. The method uses an acidified solvent extraction, an immunoaffinity column (IAC) for clean-up, liquid chromatography-tandem mass spectrometry (LC-MS/MS) for identification and quantification, and a uniformly stable isotope-labelled OTA (U-[(13)C(20)]-OTA) as an internal recovery standard. Results are corrected for this standard. The method is accurate (101% average recovery) and precise (5.5% relative standard deviation (RSD)) based on 17 duplicate analysis of various food products over 2 years. A total of 140 diet composites were analysed for OTA as part of the Canadian Total Diet Study. Samples were collected at retail level from two Canadian cities, Quebec City and Calgary, in 2008 and 2009, respectively. The results indicate that 73% (102/140) of the samples had detectable levels of OTA, with some of the highest levels of OTA contamination found in the Canadian bread supply.
Notes
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PubMed ID
21623499 View in PubMed
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Are intraaortic balloons suitable for reuse? A survey study of 112 used intraaortic balloons.

https://arctichealth.org/en/permalink/ahliterature209468
Source
Artif Organs. 1997 Feb;21(2):121-30
Publication Type
Article
Date
Feb-1997
Author
M. Yang
X. Deng
Z. Zhang
M. Julien
F. Pelletier
D. Desaulniers
R. Cossette
F J Teijeira
G. Laroche
R. Guidoin
Author Affiliation
Department of Surgery, Laval University, Quebec, Canada.
Source
Artif Organs. 1997 Feb;21(2):121-30
Date
Feb-1997
Language
English
Publication Type
Article
Keywords
Calibration
Calorimetry, Differential Scanning
Catheterization
Data Collection
Equipment Reuse - standards
Humans
Intra-Aortic Balloon Pumping - standards - trends
Longitudinal Studies
Microscopy, Electron, Scanning
Polyurethanes - chemistry
Quebec
Spectrophotometry, Infrared
Surface Properties
Tensile Strength
Abstract
To assess the safety of reusing single-use intraaortic balloon devices (IABs), 112 used devices were investigated in terms of physical integrity, gas leakage inspection, mechanical performance, surface chemistry and morphology, and physical stability. These IABs were all used clinically only once, and the duration of the IABs in vivo ranged from 6 to 312 h. Macroscopic examination of the balloons and the outer catheters revealed no obvious change in either shape or color. No discernible abrasions or cracks were observed on the balloons. However, 61% of the balloons were creased, and 40% of the central lumens and 21% of the sheaths showed visible bending flaws. Moreover, 65% of the balloons and 38% of the central lumens were contaminated by visible residual organic debris. The physical integrity of each device was verified in a specially designed leakage-fatigue tester for 72 h. Ninety-seven percent of the devices passed the leakage inspection. Stress-strain testing, differential scanning calorimetry, attenuated total reflection-Fourier transform infrared, and scanning electron microscopy analyses clearly indicated that there were no significant differences in the mechanical properties, bulk material morphology, surface chemistry, and external surface morphology between the used balloons and virgin controls. Although some surface modifications occurred on the internal side of the balloons, the external surfaces of most balloons suffered no trauma. Most of the used IABs examined in this study maintained physical and mechanical properties similar to those of the virgin devices. The chemistry of the balloon material was stable after short-term in vivo use. However, it does not seem possible to establish a rigorous protocol of cleaning, sterilization, and inspection to guarantee a safer reuse of these devices. The presence of residual organic debris that cannot be eliminated results in an imperative preclusion not to reuse the IABs.
Notes
Erratum In: Artif Organs 1998 Jan;22(1):96
PubMed ID
9028494 View in PubMed
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160 records – page 1 of 16.