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Minimum Age (minimum + age)
Selected AbstractsDating young geomorphic surfaces using age of colonizing Douglas fir in southwestern Washington and northwestern Oregon, USA,EARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2007Thomas C. Pierson Abstract Dating of dynamic, young (<500 years) geomorphic landforms, particularly volcanofluvial features, requires higher precision than is possible with radiocarbon dating. Minimum ages of recently created landforms have long been obtained from tree-ring ages of the oldest trees growing on new surfaces. But to estimate the year of landform creation requires that two time corrections be added to tree ages obtained from increment cores: (1) the time interval between stabilization of the new landform surface and germination of the sampled trees (germination lag time or GLT); and (2) the interval between seedling germination and growth to sampling height, if the trees are not cored at ground level. The sum of these two time intervals is the colonization time gap (CTG). Such time corrections have been needed for more precise dating of terraces and floodplains in lowland river valleys in the Cascade Range, where significant eruption-induced lateral shifting and vertical aggradation of channels can occur over years to decades, and where timing of such geomorphic changes can be critical to emergency planning. Earliest colonizing Douglas fir (Pseudotsuga menziesii) were sampled for tree-ring dating at eight sites on lowland (<750 m a.s.l.), recently formed surfaces of known age near three Cascade volcanoes , Mount Rainier, Mount St. Helens and Mount Hood , in southwestern Washington and northwestern Oregon. Increment cores or stem sections were taken at breast height and, where possible, at ground level from the largest, oldest-looking trees at each study site. At least ten trees were sampled at each site unless the total of early colonizers was less. Results indicate that a correction of four years should be used for GLT and 10 years for CTG if the single largest (and presumed oldest) Douglas fir growing on a surface of unknown age is sampled. This approach would have a potential error of up to 20 years. Error can be reduced by sampling the five largest Douglas fir instead of the single largest. A GLT correction of 5 years should be added to the mean ring-count age of the five largest trees growing on the surface being dated, if the trees are cored at ground level. This correction would have an approximate error of ±5 years. If the trees are cored at about 1·4 m above the ground surface (breast height), a CTG correction of 11 years should be added to the mean age of the five sampled trees (with an error of about ±7 years). Published in 2006 by John Wiley & Sons, Ltd. [source] Genomic convergence to identify candidate genes for Alzheimer Disease on chromosome 10HUMAN MUTATION, Issue 3 2009Xueying Liang Abstract A broad region of chromosome 10 (chr10) has engendered continued interest in the etiology of late-onset Alzheimer Disease (LOAD) from both linkage and candidate gene studies. However, there is a very extensive heterogeneity on chr10. We converged linkage analysis and gene expression data using the concept of genomic convergence that suggests that genes showing positive results across multiple different data types are more likely to be involved in AD. We identified and examined 28 genes on chr10 for association with AD in a Caucasian case-control dataset of 506 cases and 558 controls with substantial clinical information. The cases were all LOAD (minimum age at onset ,60 years). Both single marker and haplotypic associations were tested in the overall dataset and 8 subsets defined by age, gender, ApoE and clinical status. PTPLA showed allelic, genotypic and haplotypic association in the overall dataset. SORCS1 was significant in the overall data sets (p=0.0025) and most significant in the female subset (allelic association p=0.00002, a 3-locus haplotype had p=0.0005). Odds Ratio of SORCS1 in the female subset was 1.7 (p<0.0001). SORCS1 is an interesting candidate gene involved in the A, pathway. Therefore, genetic variations in PTPLA and SORCS1 may be associated and have modest effect to the risk of AD by affecting A, pathway. The replication of the effect of these genes in different study populations and search for susceptible variants and functional studies of these genes are necessary to get a better understanding of the roles of the genes in Alzheimer disease. 30, 463,471, 2009. © 2008 Wiley-Liss, Inc. [source] Of squeezers and skippers: factors determining the age at moult of immature African Penguins Spheniscus demersus in NamibiaIBIS, Issue 2 2005JESSICA KEMPER We used banding and resighting records of 391 African Penguins Spheniscus demersus banded as chicks and later resighted during immature moult to explain the roles of date of fledging and age at moult in determining the season of moult and its timing within the season. Breeding was continuous, but immature moult occurred mainly during spring and summer. Age at immature moult extended over 11 months, from 12 to 23 months after hatching. Birds that fledged during summer and early autumn generally moulted during the next moult season (squeezers), whereas birds that fledged in late autumn, winter and spring skipped the next moult season to moult only the following season (skippers). There was a significant relationship between age at moult and moult date, with young birds moulting later in the season than older birds. The age at moult of immature birds appears to be constrained by minimum age, moult seasonality and plumage wear. Birds that fledged over nearly 2 years moult during one season. Counts of moulting immature African Penguins have not been used to estimate year-class strength and post-fledging survival owing to the wide range of ages at immature moult. Our results provide the means of assigning recruits to specific age groups. [source] Nesting area fidelity and survival of female Common Goldeneyes Bucephala clangula: are they density-dependent?IBIS, Issue 3 2002Ingo Ludwichowski The breeding histories of 218 female Common Goldeneyes Bucephala clangula were recorded between 1971 and 2000 in a study area in Schleswig-Holstein, northern Germany. Females were first recorded breeding at a median age of 2 years usually in their area of hatching (philopatry). One hundred and two of 140 females (73%) re-nested only in one of the 13 nesting areas (clusters of nestboxes) for all their known life of up to 13 breeding seasons. The remaining 38 individuals moved between different nesting areas at least once between breeding attempts. The two oldest females were still breeding at a minimum age of 15 years (i.e. 13 years between first and last recorded breeding attempt). Temporal variations in annual survival rates of adult females could best be explained by a model with annual survival rate varying independently and randomly about a mean of 0.830 (se = ±0.023) with an estimated sd of ±0.092 (95% CI = 0.064, 0.138). No trend in the annual survival rate was detected over the study period of 30 years, although the presence of a moderate trend could not be ruled out. The absence of any discernible trend in survival at a time when the population size increased substantially indicates little, if any, density-dependence in survival of female Goldeneyes during this study. [source] Agitation in the morning: symptom of depression in dementia?INTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 4 2009Anna-Katharina Theison Abstract Objective To investigate the possible correlations between depression in dementia and agitation in the morning by a prospective naturalistic study. Methods Data were collected from three independent nursing homes in an urban setting. Trained nursing home staff pre-selected 110 demented and agitated patients with a minimum age of 60 years. Three main groups were formed based on agitation peak either: in the morning, evening or none. Each is respectively: ,sunrisers', ,sundowners' and ,constants'. Agitation was assessed by the same staff twice a day for a 2-week timeframe using the CMAI (Cohen-Mansfield Agitation Inventory); MMSE (Mini-Mental State Examination) for dementia re-evaluation and staging; CSDD (Cornell Score for Depression in Dementia) for depression screening. Results Sixty-three (60%) of all patients were depressive but only 16 patients of them were treated with antidepressants. Forty-four patients were classified as belonging to the ,sunriser' group, 38 to the ,sundowners' and 23 to the ,constants'. There were no significant differences in depression between the three groups: p,=,0.798 for the difference in proportion of depressed or not depressed people; p,=,0.272 for the difference in raw Cornell-score between agitation in the morning and evening. Conclusion ,Sunrising' appears to play an important role in dementia. In our population agitation was slightly more common in the morning than in the evening, but peak of agitation does not seem to be related to depression in dementia. Our data supports that the diagnosis of depression is still often overlooked in demented and agitated persons. Copyright © 2008 John Wiley & Sons, Ltd. [source] The effects of ECT on cognitive functioning in the elderly: a reviewINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 8 2008Caroline E. M. Tielkes Abstract Background Electroconvulsive therapy (ECT) as a single course or in maintenance form (M-ECT) is an effective treatment in depressed elderly. However, ECT may have adverse effects on cognition. Objective To review all studies from 1980,2006 on ECT and cognition in the elderly with a minimum age of 55 years or a mean age of 55 years, and with valid measurements of cognition before and after ECT. Results Nine out of the 15 eligible studies were focused exclusively on the elderly. Three studies reported verbal learning- and recall problems post ECT, while three studies found positive effects of ECT on memory, speed of processing and concentration. Global cognitive functioning in patients with cognitive impairment improved in all studies. At follow up, most studies reported improvement of cognitive functions. Learning verbal information and executive functioning were impaired in M-ECT patients whereas global cognition remained stable after M-ECT over a year. Conclusions To date research of ECT on cognitive functioning in the elderly is very limited. Small sample size, lack of controls, use of a single screening instrument and a short follow up period may explain the conflicting results. Given the clinical importance, more extensive research on cognition in elderly treated with ECT is urgently needed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Millennium-scale recurrent uplift inferred from beach deposits bordering the eastern Nankai Trough, Omaezaki area, central JapanISLAND ARC, Issue 3 2010Osamu Fujiwara Abstract A flight of Holocene marine terraces on the southwestern coast of Cape Omaezaki of central Japan provides evidence of recurrent millennium-scale uplift events. We reconstructed the uplift history of these terraces by using facies analysis of drill core and geoslicer samples, environmental analysis of trace fossils, and 14C age determinations. Coastal uplift can be identified by the displacement of beach deposits such as foreshore deposits, which represent the intertidal swash zone of a wave-dominated sandy coast. Three levels of former beach deposits facing the Nankai Trough were identified near the coast in the Omaezaki area. The highest of these, dated at about 3020,2880 BC, records a maximum of 2.2,2.7 m of emergence. The middle beach surface, of minimum age 370,190 BC, shows 1.6,2.8 m of emergence. The lowest beach surface, which is older than 1300,1370 AD, records 0.4,1.6 m of emergence. Our analysis of vertical crustal deformation data during the Holocene in this region suggests that rapid and strong uplift was restricted to the southwestern coast of the Omaezaki area and was probably caused by high-angle thrusting on subsidiary faults branching from the underlying plate boundary megathrust. [source] Reciprocal distribution of two congeneric trees, Betula platyphylla var. japonica and Betula maximowicziana, in a landscape dominated by anthropogenic disturbances in northeastern JapanJOURNAL OF BIOGEOGRAPHY, Issue 12 2005Katsuhiro Osumi Abstract Aim, Information has been compiled on disturbance regimes and the life-history characteristics of Betula platyphylla var. japonica (Miq.) Hara and B. maximowicziana Regel to investigate the impact of humans on the present distribution patterns of these two congeneric tree species. Location, The study area is in the central region of the northern Kitakami Mountain Range, located in the northeast of Honshu Island, Japan. Methods, First, the present distributions of B. maximowicziana and B. platyphylla var. japonica were mapped at the landscape scale. To examine the factors affecting the distribution patterns, topographic features and past land use were taken into account. Second, life-history traits of both species were clarified at various growth stages either by fieldwork or through a literature search. Previous studies have provided some information on seed production, seed dispersal, seedling dynamics, sprouting, and growth. In the present study, field observations and experiments were conducted regarding seed-bank formation, size and age at reproduction, and the life span of canopy trees. Results,Betula platyphylla var. japonica and B. maximowicziana were spatially segregated in the studied landscape (14,000 ha). The distribution of each species was correlated more strongly with land use at the beginning of the twentieth century than with site environmental factors such as altitude or slope angle. Betula platyphylla var. japonica was distributed more frequently on former grasslands, whereas B. maximowicziana was almost exclusively limited to past old-growth forests. As typical pioneers, the two species showed similar life-history traits but differed in several critical points. Betula platyphylla var. japonica has a vigorous sprouting ability, which might increase its resistance to burning and logging, whereas B. maximowicziana forms a persistent seed bank in the soil, indicating an advantage in regenerating in disturbances found in forest communities. Other critical differences were detected in age-related characteristics such as minimum age of reproduction and life span. Main conclusions, The earlier reproductive maturity and the shorter life span of B. platyphylla var. japonica indicate a shorter population cycle than that for B. maximowicziana. The latter would be excluded from grasslands that were burned frequently, as a result of the longer time span before initial reproduction and its poor sprouting ability. In contrast, B. platyphylla var. japonica would be excluded from old-growth forests, where disturbance was infrequent, owing to its shorter life span and lack of a persistent seed bank. [source] Continuous, age-related plumage variation in male Kirtland's WarblersJOURNAL OF FIELD ORNITHOLOGY, Issue 1 2007John R. Probst ABSTRACT The ability to age individual birds visually in the field based on plumage variation could provide important demographic and biogeographical information. We describe an approach to infer ages from a distribution of plumage scores of free-ranging male Kirtland's Warblers (Dendroica kirtlandii). We assigned ages to males using a scoring scheme (0,12 points) based on variation in plumage coloration, brightness, and contrast on three dorsal and three ventral body regions presumed to be age-related. The distribution of total additive plumage scores for 875 breeding males was normally distributed, indicating no distinct age classes. Thus, we developed provisional plumage-age classes of second year (SY) and after second-year (ASY), and compared them to the total plumage scores of a smaller subsample of known age (N= 92) and minimum age (N= 143) males. Plumage scores of known-age male Kirtland's Warblers increased nonlinearly with age (rs= 0.67), but with some overlap. The median plumage score for SY males (median = 5.0) was significantly lower than for third-year (TY) males (median = 7.0) and after third-year (3 year and older) males (median = 8.0), indicating that the plumage of male Kirtland's Warblers becomes more distinctive and brighter with age. Linear discriminant function analysis differentiated ASY male Kirtland's Warbler from SY males with 78.3% accuracy. Investigators could use the distribution of plumage scores and approximate age structures to document changes in male age structure during colonization, use, and abandonment of habitats by Kirtland's Warblers or other species that occupy early successional habitats. Aging free-ranging birds based on a plumage scoring scheme may be especially critical for demographic studies of less-studied species where it is unlikely that a banding program will be initiated, but where plumage-age inferences or management decisions must be made. SINOPSIS Describimos una forma para inferir la edad a través de una distribución de marcadores en machos silvestres de la reinita Dendroica kirtlandii. Utilizando dicho acercamiento, asignamos edad relativa a machos basándonos en un esquema de puntuación (0,12) para la coloración del plumaje, su brillantez, y contraste en tres localidades del dorso y la parte ventral, que han sido relacionadas con la edad de estos. La distribución de las puntuaciones de 875 machos fue normal, lo que indica que no hubo forma de distinguir las diferentes edades. Por ende, desarrollamos un divisiones de clases, basándonos en diferencias en el plumaje para individuos de segundo año (SA) y posterior al segundo año (PSA) y los comparamos a las puntuaciones de una pequeña muestra de aves (N= 92) cuya edad era conocida y a otra en que sabíamos la edad mínima (N= 143). La puntuación total para individuos de edad conocida aumento de forma no-lineal con la edad (Rs = 0.67), con un pequeño solapamiento en el plumaje total. La puntuación para machos de segundo año (SA) (mediana = 5.0) fue significativamente menor que para aves de tercer año (mediana = 7.0) y esta a su vez que para aves mayores a tres años (mediana = 8.0), lo que indica que el plumaje de los machos, en las aves estudiadas, se torna más brillante con la edad. Un análisis lineal de función discriminativa pudo diferenciar entre aves PSA y SA con un 78.3% de exactitud. Los investigadores han utilizado estas diferencias en el plumaje para clasificar entre los grupos machos territoriales que no han sido anillados. También pudieran utilizar estas particularidades y diferencias en el plumaje para aproximar la estructura de edades entre machos silvestres y hacer inferencias sobre la demografía y reclutamiento de aves en habitats de diferente calidad. [source] Western Australian cigarette smokers have fewer small lung nodules than North Americans on CT screening for lung cancerJOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 4 2009CP Murray Summary To determine the prevalence of small lung nodules on low-dose helical computed tomography (CT) in a Western Australian cohort of asymptomatic long-term cigarette smokers and to compare this with a large, similarly derived cohort of North Americans from the Mayo Clinic Lung Cancer Screening Trial. Forty-nine asymptomatic long-term cigarette smokers of minimum age 50 years underwent a low-dose 64-slice helical CT of the lungs. Images were viewed on a soft copy reporting station with thin section axial and coronal images, maximum intensity projection images, and advanced image manipulation tools. The prevalence of all nodules was 39%, significantly lower than the Mayo Clinic cohort prevalence of 51% (P < 0.01, Fisher's exact test), despite the use of more advanced imaging technology and image manipulation designed to increase the sensitivity for nodules. The prevalence of small nodules in asymptomatic long-term cigarette smokers in Western Australia is high, though significantly less than that found in a large study in North America. The authors postulate this is due to the relatively low rates of mycobacterium tuberculosis and soil-derived fungal pulmonary infections in Western Australia, as well as a lower degree of urban air pollution. [source] Neoproterozoic high-pressure/low-temperature metamorphic rocks in the Avalon terrane, southern New Brunswick, CanadaJOURNAL OF METAMORPHIC GEOLOGY, Issue 5 2001C. E. White Abstract High -P/low -T metamorphic rocks of the Hammondvale metamorphic suite (HMS) are exposed in an area of 10 km2 on the NW margin of the Caledonian (Avalon) terrane in southern New Brunswick, Canada. The HMS is in faulted contact on the SE with c. 560,550 Ma volcanic and sedimentary rocks and co-magmatic plutonic units of the Caledonian terrane. The HMS consists of albite- and garnet-porphyroblastic mica schist, with minor marble, calc-silicate rocks and quartzite. Pressure and temperature estimates from metamorphic assemblages in the mica schist and calc-silicate rocks using TWQ indicate that peak pressure conditions were 12.4 kbar at 430 °C. Peak temperature conditions were 580 °C at 9.0 kbar. 40Ar/39Ar muscovite ages from three samples range up to 618,615 Ma, a minimum age for high -P/low- T metamorphism in this unit. These ages indicate that the HMS is related to the c. 625,600 Ma subduction-generated volcanic and plutonic units exposed to the SE in the Caledonian terrane. The ages are also similar to those obtained from detrital muscovite in a Neoproterozoic-Cambrian sedimentary sequence in the Caledonian terrane, suggesting that the HMS was exposed by latest Neoproterozoic time and supplied detritus to the sedimentary units. The HMS is interpreted to represent a fragment of an accretionary complex, similar to the Sanbagawa Belt in Japan. It confirms the presence of a major cryptic suture between the Avalon terrane sensu stricto and the now-adjacent Brookville terrane. [source] Surface exposure dating of the Great Aletsch Glacier Egesen moraine system, western Swiss Alps, using the cosmogenic nuclide 10BeJOURNAL OF QUATERNARY SCIENCE, Issue 5 2004Meredith A. Kelly Abstract Egesen moraines throughout the Alps mark a glacial advance that has been correlated with the Younger Dryas cold period. Using the surface exposure dating method, in particular the measurement of the cosmogenic nuclide 10Be in rock surfaces, we attained four ages for boulders on a prominent Egesen moraine of Great Aletsch Glacier, in the western Swiss Alps. The 10Be dates range from 10,460±1100 to 9040±1020,yr ago. Three 10Be dates between 9630±810 and 9040±1020,yr ago are based upon samples from the surfaces of granite boulders. Two 10Be dates, 10,460±1100 and 9910±970,yr ago, are based upon a sample from a quartz vein at the surface of a schist boulder. In consideration of the numerous factors that can influence apparently young 10Be dates and the scatter within the data, we interpret the weighted mean of four boulder ages, 9640±430,yr (including the weighted mean of two 10Be dates of the quartz vein), as a minimum age of deposition of the moraine. All 10Be dates from the Great Aletsch Glacier Egesen moraine are consistent with radiocarbon dates of nearby bog-bottom organic sediments, which provide minimum ages of deglaciation from the moraine. The 10Be dates from boulders on the Great Aletsch Glacier Egesen moraine also are similar to 10Be dates from Egesen moraines of Vadret Lagrev Glacier on Julier Pass, in the eastern Swiss Alps. Both the morphology of the Great Aletsch Glacier Egesen moraine and the comparison with 10Be dates from the inner Vadret Lagrev Egesen moraine support the hypothesis that the climatic cooling that occurred during the Younger Dryas cold episode influenced the glacial advance that deposited the Great Aletsch Glacier Egesen moraine. Because of the large size and slow response time of Great Aletsch Glacier, we suggest that the Great Aletsch Glacier Egesen moraine was formed during the last glacial advance of the multiphased Egesen cold period, the Kromer stage, during the Preboreal chron. Copyright © 2004 John Wiley & Sons, Ltd. [source] Chronology of the last recession of the Greenland Ice SheetJOURNAL OF QUATERNARY SCIENCE, Issue 3 2002Ole Bennike Abstract A new deglaciation chronology for the ice-free parts of Greenland, the continental shelf and eastern Ellesmere Island (Canada) is proposed. The chronology is based on a new compilation of all published radiocarbon dates from Greenland, and includes crucial new material from southern, northeastern and northwestern Greenland. Although each date provides only a minimum age for the local deglaciation, some of the dates come from species that indicate ice-proximal glaciomarine conditions, and thus may be connected with the actual ice recession. In addition to shell dates, dates from marine algae, lake sediments, peat, terrestrial plants and driftwood also are included. Only offshore and in the far south have secure late-glacial sediments been found. Other previous reports of late-glacial sediments (older than 11.5 cal. kyr BP) from onshore parts of Greenland need to be confirmed. Most of the present ice-free parts of Greenland and Nares Strait between Greenland and Ellesmere Island were not deglaciated until the early Holocene. Copyright © 2002 John Wiley & Sons, Ltd. [source] No Association between SNP rs498055 on Chromosome 10 and Late-Onset Alzheimer Disease in Multiple DatasetsANNALS OF HUMAN GENETICS, Issue 1 2008Xueying Liang Summary SNP rs498055 in the predicted gene LOC439999 on chromosome 10 was recently identified as being strongly associated with late-onset Alzheimer disease (LOAD). This SNP falls within a chromosomal region that has engendered continued interest generated from both preliminary genetic linkage and candidate gene studies. To independently evaluate this interesting candidate SNP we examined four independent datasets, three family-based and one case-control. All the cases were late-onset AD Caucasian patients with minimum age at onset , 60 years. None of the three family samples or the combined family-based dataset showed association in either allelic or genotypic family-based association tests at p < 0.05. Both original and OSA two-point LOD scores were calculated. However, there was no evidence indicating linkage no matter what covariates were applied (the highest LOD score was 0.82). The case-control dataset did not demonstrate any association between this SNP and AD (all p-values > 0.52). Our results do not confirm the previous association, but are consistent with a more recent negative association result that used family-based association tests to examine the effect of this SNP in two family datasets. Thus we conclude that rs498055 is not associated with an increased risk of LOAD. [source] Petrographic and SHRIMP Studies of Zircons from the Caledonian Xiongdian Eclogite, Northwestern Dabie MountainsACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 4 2000JIAN Ping Abstract The Xiongdian eclogite occurring in the Sujiahe tectonic mélange zone at Luoshan County, Henan Province, in the western Dabie Mountains, is typical high-pressure (HP)-ultrahigh-pressure (UHP) and medium-temperature eclogite. The occurrence, internal texture and surface characteristics of zircons in eclogite were studied rather systematically petrographically combined with the cathodoluminescence (CL) and scanning electron microscope (SEM) methods. Zircons are mainly hosted in garnet and other metamorphic minerals with sharp boundaries, have a multifaceted morphology and are homogeneous or exhibit a metamorphic growth texture in the interior, thus indicating that they are the product of metamorphism. SHRIMP analyses give zircon 206Pb/238U ages of 335 to 424 Ma and show a certain degree of radiogenic Pb loss; therefore it may be inferred that the age of 424±5 Ma represents the minimum age of a HP-UHP metamorphic age. From the above analyses coupled with previous Sm-Nd, 40Ar- 39Ar, U-Pb and 207Pb/206Pb age data, it is suggested that the peak metamorphic age of the Xiongdian eclogite should be between 424 and 480 Ma. This study further validate the view of the existence of a Caledonian HP-UHP metamorphic event in the western Dabie Mountains. [source] Surface exposure dating of the Great Aletsch Glacier Egesen moraine system, western Swiss Alps, using the cosmogenic nuclide 10BeJOURNAL OF QUATERNARY SCIENCE, Issue 5 2004Meredith A. Kelly Abstract Egesen moraines throughout the Alps mark a glacial advance that has been correlated with the Younger Dryas cold period. Using the surface exposure dating method, in particular the measurement of the cosmogenic nuclide 10Be in rock surfaces, we attained four ages for boulders on a prominent Egesen moraine of Great Aletsch Glacier, in the western Swiss Alps. The 10Be dates range from 10,460±1100 to 9040±1020,yr ago. Three 10Be dates between 9630±810 and 9040±1020,yr ago are based upon samples from the surfaces of granite boulders. Two 10Be dates, 10,460±1100 and 9910±970,yr ago, are based upon a sample from a quartz vein at the surface of a schist boulder. In consideration of the numerous factors that can influence apparently young 10Be dates and the scatter within the data, we interpret the weighted mean of four boulder ages, 9640±430,yr (including the weighted mean of two 10Be dates of the quartz vein), as a minimum age of deposition of the moraine. All 10Be dates from the Great Aletsch Glacier Egesen moraine are consistent with radiocarbon dates of nearby bog-bottom organic sediments, which provide minimum ages of deglaciation from the moraine. The 10Be dates from boulders on the Great Aletsch Glacier Egesen moraine also are similar to 10Be dates from Egesen moraines of Vadret Lagrev Glacier on Julier Pass, in the eastern Swiss Alps. Both the morphology of the Great Aletsch Glacier Egesen moraine and the comparison with 10Be dates from the inner Vadret Lagrev Egesen moraine support the hypothesis that the climatic cooling that occurred during the Younger Dryas cold episode influenced the glacial advance that deposited the Great Aletsch Glacier Egesen moraine. Because of the large size and slow response time of Great Aletsch Glacier, we suggest that the Great Aletsch Glacier Egesen moraine was formed during the last glacial advance of the multiphased Egesen cold period, the Kromer stage, during the Preboreal chron. Copyright © 2004 John Wiley & Sons, Ltd. [source] Setting new constraints on the age of the UniverseMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2001Ignacio Ferreras There are three independent techniques for determining the age of the Universe: via cosmochronology of long-lived radioactive nuclei, via stellar modelling and population synthesis of the oldest stellar populations, and, most recently, via the precision cosmology that has become feasible with the mapping of the acoustic peaks in the cosmic microwave background. We demonstrate that all three methods give completely consistent results, and enable us to set rigorous bounds on the maximum and minimum ages that are allowed for the Universe. We present new constraints on the age of the Universe by performing a multiband colour analysis of bright cluster ellipticals over a large redshift range , which allows us to infer the ages of their stellar populations over a wide range of possible formation redshifts and metallicities. Applying a prior to Hubble's constant of we find the age of the Universe to be (1,), in agreement with the estimates from Type Ia supernovae, as well as with the latest uranium decay estimates, which yield an age for the Milky Way of . If we combine the results from cluster ellipticals with the analysis of the angular power spectrum of the cosmic microwave background and with the observations of Type Ia supernovae at high redshift, we find a similar age: . Without the assumption of any priors, universes older than 18 Gyr are ruled out by the data at the 90 per cent confidence level. [source] Assignment of work involving farm tractors to children on North American farms,AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 1 2001Barbara Marlenga PhD Abstract Background Children are at high risk for tractor-related injury. The North American Guidelines for Children's Agricultural Tasks (NAGCAT) provide recommendations for the assignment of tractor work. This analysis describes tractor-related jobs assigned to farm children and compares them to NAGCAT. Methods A descriptive analysis was conducted of baseline data collected by telephone interview during a randomized, controlled trial. Results The study population consisted of 1,138 children who worked on 498 North American farms. A total of 2,389 farm jobs were reported and 456 (19.1%) involved operation of farm tractors. Leading types of tractor jobs were identified. Modest, yet important, percentages of children were assigned tractor work before the minimum ages recommended by NAGCAT. Conclusions Children on farms are involved in tractor work at a young age and some are involved in jobs that they are unlikely to have the developmental abilities to perform. NAGCAT is a new parental resource that can be applied to these work situations. Am. J. Ind. Med. 40:15,22, 2001. © 2001 Wiley-Liss, Inc. [source] Chronology of deglaciation based on 10Be dates of glacial erosional features in the Grimsel Pass region, central Swiss AlpsBOREAS, Issue 4 2006MEREDITH A. KELLY Surface exposure dating, using in situ produced cosmogenic 10Be, is applied to determine the time since deglaciation of bedrock surfaces in the Grimsel Pass region. Nine 10Be dates from bedrock surfaces corrected for cover by snow are minimum ages for deglaciation of the pass. Four 10Be dates from surfaces below 2500 meters above sea level (m a.s.l.) on Nägelisgrätli, east of Grimsel Pass, yield ages that range from about 14 000 to 11 300 years. Three 10Be dates from locations above 2600 m a.s.l. on Nägelisgrätli are between about 11 700 and 10 400 years. Two 10Be dates from locations at 2560 m a.s.l. below Juchlistock are about 12 100 and 11 000 years. The geographical distribution of 10Be dates on Nägelisgrätli either may show the timing of progressive deglaciation of Grimsel Pass or may reflect differences in subglacial erosion of bedrock in the pass region. All dates are discussed in the context of deglaciation of the late Würmian Alpine ice cap and deglaciation from Last Glacial Maximum (LGM) ice extents in other regions. [source] | |||||||||||||||||||