Age ranges

Supposing that the rate of production of fresh surface per unit total area of surface is. s, and that s is independent of the age of the element in question, the area of surface of age between t and t + dr will be a function of r and may be written as f(r) dr. This will be equal to the area passing in time dr from the age range l(r — dr) to r ] to the age range r to (r + dr)]. Further, this in turn will be equal to the area in the age group f(r - dr) to /], less that replaced by fresh surface in time dr, or ... 

Tabic 1.1. Amino acids per thousand residues for standard type 1 collagen and 15 human bone collagen samples from St. Thomas Church cemetery. Samples are identified by burial numlter (Bx) followed by age midpoint for subadults and age range for adults in parentheses. For example, B17(0) refers to burial 17 who was aged as a newborn. 

These sites cover a great age range and may be either palaeontological accumulations or archaeological living sites. Makapansgat Member 3 is the oldest at about 3Ma (MacFadden et al. 1979), while Members 1-3 at Swartkrans span a period of about 1.8 to l.OMa (Brain et al. 1988). Both have faunal material accumulated in now-collapsed karstic caverns or shelters, and... 

The only other information regarding the potential for age-related differences in susceptibility to methyl parathion came from a study by Garcia-Lopez and Monteoliva (1988). The investigators showed increasing mean erythrocyte acetylcholinesterase activity levels with increasing age range, starting at birth (in 10-year increments and >60 years of age) in both males and females. However, it is not known whether increased erythrocyte acetylcholinesterase activity indicates a decreased susceptibility to methyl parathion toxicity. 

Fig. 3.4. Range chart of back-arc basin formation. Solid lines show confined age ranges of the formation of marginal basins by seafloor spreading, and broken lines show rough estimates of the age range. Rhombic marks show the timing of entrapment of the basins (Tamaki and Honza, 1991).

Eluorescence of both collagen (Monnier etal., 1986) and IgG (Jones etal., 1988) are associated with diabetic micrOangiopathy. Monnier etal. (1986) found that measured collagen-linked fluorescence in skin biopsies from both patients with type 1 diabetes ( = 41, age range 29-52 years) and controls ( =25, age range 28-41 years) was significantly correlated with the severity of retinopathy as well as arterial and joint stifihess. Jones et al. (1988) found increased fluorescence of serum IgG in diabetic patients with... 

Several volcanic centers from the Kenya Rift Valley in East Africa were studied by Black et al. (1997, 1998). Four U-Th isochrons were obtained from trachytes from Emuruangogolak and Paka volcanoes (Black et al. 1998) their crystallization ages range from 9.3 to 39.5 ka and are in full agreement with in situ Ar- Ar laser dating of... 

Figure 24. Measured 6 Tla) vs. Th diagram used to infer the ages of lava flows from Mt. Etna in the age range 0 to 8 ka. The eurves labeled 0, 0.5, 1... ka correspond to isochron curves. The isochron 0 is defined by the 6 Tla)o-Th correlation observed in historical lava flows of the last two millennia (Condomines et al. 1995). Five samples of previously unknown ages are reported in this diagram (Condomines et al. 1995, and unpublished results).

Dating of whole rocks from the measurements of their °Th- U or Pa- U disequilibria has been successful in the case of MORE, and can also be applied to volcanoes for which the evolution of these disequilibria through time has been studied in detail (e.g., Piton de la Foumaise). Similarly Ra- Th disequilibria may be useful dating tools in the age range 0 to 8 ka, for MORE or continental volcanoes where a detailed knowledge of their variations in well dated samples is available. 

Figure 12. Profiles of Th to Nb ratios for four Hawaiian soils developed on lava flows with ages ranging from 20 ka to 4100 ka (Kurtz et al. 2000). In these soils, Nb is assumed to be an irmnobile element. Variations of Th/Nb ratios, with lower values than those of basalt (greyed area) in the upper part of the profile and higher values in the lower part indieate an internal downward migration of Th in these fom weathering profiles. Cireles = 20 ka Laupahoehoe site, triangles = 150 ka Kohala site, squares = 1400 ka Molokai site, diamonds = 4100 ka Kauai site.

As one might suspect, the modal age range of the arrestees was the twenties. Almost one-half of the men (47 percent) were age 25 or less, and only 19 percent were 36 or older. The majority of the men (54 percent) were black, with a sizable minority (33 percent) being of Hispanic descent. Ten percent of the sample members were white. Education was limited in the men. More than one half (56 percent) never completed high school or its equivalent (GED). 

The sociodemographic and clinical characteristics of our PCP abusers were similar to those previously reported in the literature, except for a somewhat older age range. This indicates that chronic PCP use does occur outside the adolescent/young adult age group, and suggests that future treatment and research efforts should include older age groups. 

Inflammatory bowel disease is most common in westernized countries such as the United States. Ulcerative colitis affects up to 500,000 people and Crohn s disease affects up to 480,000 people in the United States.2-4 The age of initial presentation of IBD is bimodal, with patients typically diagnosed between the age ranges of 20 to 40 years or 60 to 80 years.5 The peak incidence of CD occurs in the second and third decades of life, with a smaller peak in the fifth decade.2,5 Peak incidence of UC occurs between the ages of 15 and 25 years.6... 

Cr 261 is one of the oldest open clusters in the Galaxy, with an estimated age ranging from 7 to 11 Gyr ([5] [16] [4]). The metallicity, derived from both low-resolution and high-resolution spectra, is slightly subsolar ([Fe/H]=—0.2 ... 

See for example, from the 19th International Radiocarbon Conference held in 2006 A.G. Hogg, L.K. Fifield, J.G. Palmer, C.S.M. Turney and R. Galbrait, Robust radiocarbon dating of wood samples by high sensitivity liquid scintillation spectroscopy in the 50 70 kyr age range, Radiocarbon 49,379 391 (2007). 

Recent measurements indicate that the relatively high C02 concentrations determined for part of the holocene ice probably are due to contamination of the ice core which for this age range shows many small cracks. 

For those who are concerned with the preparation of samples for the direct 14C counting systems, this summary vividly illustrates the effects on the final age value as a result of the addition of ppm levels of modern carbon for samples in different age ranges. For a sample with an actual age of 75,000 years, for example, a 100 ppm addition of modern carbon results in approximately a 5000-year error in the final measured age. Hopefully, contamination of a sample with modern carbon would be a relatively rare occurrence. A more probable situation would involve the addition of carbon differing in age from the original samples from several hundred up to several tens of thousands of years. 

Data on safety and efficacy outside of these age ranges are insufficient. 

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